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Page 1: International Codes v8i

STAAD.Pro

V8i (SELECTseries 2)

International Design Codes ManualDAA037810-1/0003

Last updated: 6 March 2011

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Copyright Information

TRADEMARK NOTICEBentley, the "B" Bentley logo, STAAD.Pro are registered or nonregisteredtrademarks of Bentley Sytems, Inc. or Bentley Software, Inc. All other marks are theproperty of their respective owners.

COPYRIGHT NOTICE© 2011, Bentley Systems, Incorporated. All Rights Reserved.

Including software, file formats, and audiovisual displays; may only be usedpursuant to applicable software license agreement; contains confidential andproprietary information of Bentley Systems, Incorporated and/or third partieswhich is protected by copyright and trade secret law and may not be provided orotherwise made available without proper authorization.

ACKNOWLEDGMENTSWindows, Vista, SQL Server, MSDE, .NET, DirectX are registered trademarks ofMicrosoft Corporation.

Adobe, the Adobe logo, Acrobat, the Acrobat logo are registered trademarks ofAdobe Systems Incorporated.

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RESTRICTED RIGHTS LEGENDSIf this software is acquired for or on behalf of the United States of America, itsagencies and/or instrumentalities ("U.S. Government"), it is provided withrestricted rights. This software and accompanying documentation are "commercialcomputer software" and "commercial computer software documentation,"respectively, pursuant to 48 C.F.R. 12.212 and 227.7202, and "restrictedcomputer software" pursuant to 48 C.F.R. 52.227-19(a), as applicable. Use,modification, reproduction, release, performance, display or disclosure of thissoftware and accompanying documentation by the U.S. Government are subject torestrictions as set forth in this Agreement and pursuant to 48 C.F.R. 12.212,52.227-19, 227.7202, and 1852.227-86, as applicable. Contractor/Manufactureris Bentley Systems, Incorporated, 685 Stockton Drive, Exton, PA 19341- 0678.

Unpublished - rights reserved under the Copyright Laws of the United States andInternational treaties.

END USER LICENSE AGREEMENTSTo view the End User License Agreement for this product, review: eula_en.pdf.

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Table of Contents

About STAAD.Pro 2

About the STAAD.Pro Documentation 4

Getting Started and Tutorials 4

Examples Manual 4

Graphical Environment 4

Technical Reference Manual 4

International Design Codes 5

Section 1 Australian Codes 7

Australian Codes - Concrete Design per AS 3600 - 2001 9

Australian Codes - Steel Design per AS 4100 - 1998 19

Section 2 British Codes 57

British Codes - Concrete Design per BS8110 59

British Codes - Steel Design per BS5950:2000 81

British Codes - Design per BS5400 113

British Codes - Design per BS8007 119

British Codes - Design per British Cold Formed Steel Code 123

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Section 3 Canadian Codes 153

Canadian Codes - Concrete Design per CSA Standard A23.3-94155

Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01 163

Canadian Codes - Design Per Canadian Cold Formed SteelCode S136-94 207

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01 215

Section 4 Chinese Codes 247

Chinese Codes - Concrete Design Per GB50010-2002 249

Chinese Codes - Steel Design Per GBJ 50017-2003 261

Section 5 European Codes 273

European Codes - Concrete Design Per Eurocode EC2 275

European Codes - Steel Design Per Eurocode 3 283

5B.5(B).4.1 Basic stress check 313

5B.5(B).4.2 Detailed stress check 316

European Codes - Timber Design Per EC 5: Part 1-1 405

Section 6 Egyptian Codes 431

Egyptian Codes - Concrete Design Per Egyptian Code -ECCS203 433

Egyptian Codes - Steel Design Per Egyptian Code # 205 441

Section 7 French Codes 451

French Codes - Concrete Design per B.A.E.L 453

French Codes - Steel Design per the French Code 459

Section 8 German Codes 471

German Codes - Concrete Design Per DIN 1045 473

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German Codes - Steel Design Per the DIN Code 481

Section 9 Indian Codes 493

Indian Codes - Concrete Design per IS456 495

Indian Codes - Concrete Design per IS13920 521

Indian Codes - Steel Design per IS800:1984 547

Indian Codes - Steel Design per IS802 569

Indian Codes - Design per Indian Cold Formed Steel Code 593

Section 10 Japanese Codes 601

Japanese Codes - Concrete Design Per 1991 AIJ 603

Japanese Codes - Steel Design Per 2005 AIJ 613

Section 11 Mexican Codes 649

Mexican Codes - Concrete Design Per MEX NTC 1987 651

Mexican Codes - Steel Design Per Mexican Code 669

Section 12 Russian Codes 683

Russian Codes - Concrete Design Per Russian Code (SNiP2.03.01-84*) 685

Russian Codes - Steel Design Per Russian Code SNiP 2.23-81*(Edition 1999) 715

Section 13 South African Codes 737

South African Codes - Concrete Design Per SABS-0100-1 739

South African Codes - Steel Design Per SAB Standard SAB0162-1:1993 747

Section 14 American Aluminum Code 773

Section 15 American Transmission Tower Code 791

American Transmission Tower Code - Steel Design per ASCE10-97 793

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American Transmission Tower Code - Steel Design per ASCEManuals and Reports 801

Section 16 Steel Design per American Petroleum Insti-tute Code 807

Section 17 ANSI/AISC N690 Design Codes 823

ANSI/AISC N690-1994 Code 825

ANSI/AISC N690-1984 Code 845

Section 18 American Society of Mechanical Engineers– Nuclear Facility (ASME NF) Codes 869

ASME NF 3000 - 1974 & 1977 Codes 871

ASME NF 3000 - 1989 Code 883

ASME NF 3000 - 2004 Code 897

ASME NF 3000 - 2004 Code 910

Section 19 Norwegian Codes 923

Norwegian Codes - Steel Design per NS 3472 / NPD 925

Norwegian Codes - Steel Design per NORSOK N-004 983

Norwegian Codes - Concrete Design per NS 3473 1008

Section 20 Cypriot Codes 1013

Cypriot Codes - Concrete Design in Cyprus 1013

Section 21 Danish Codes 1019

Danish Codes - Steel Design per DS412 1019

Section 22 Dutch Codes 1023

Dutch Codes - Steel Design per NEN 6770 1023

Section 23 Finnish Codes 1027

Finnish Codes - Concrete Design per B4 1027

Finnish Codes - Steel Design per B7 1030

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Section 24 Singaporian Codes 1035

Singaporean Codes - Concrete Design per CP65 1035

Section 25 Spanish Codes 1041

Spanish Codes - Concrete Design per EHE 1041

Section 26 Swedish Codes 1045

Swedish Codes - Concrete Design per BBK 94 1045

Technical Support 1049

Index 1051

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This documentation has been prepared to provide information pertaining to thevarious international codes supported by STAAD. These codes are provided asadditional codes by Research Engineers. In other words, they do not come with thestandard package. Hence, information on only some of the codes presented in thisdocument may be actually pertinent to the individual user's package.

This document is to be used in conjunction with the STAAD Technical ReferenceManual and the STAAD Application Examples Manual. Effort has been made toprovide some basic information about the analysis considerations and the logicused in the design approach. A brief outline of the factors affecting the designalong with references to the corresponding clauses in the codes is also provided.Examples are provided at the appropriate places to facilitate ease of understandingof the usage of the commands and design parameters. Users are urged to refer tothe Examples Manual for solved problems that use the commands and features ofSTAAD. Since the STAAD output contains references to the clauses in the code thatgovern the design, users are urged to consult the documentation of the code of thatcountry for additional details on the design criteria.

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About STAAD.ProSTAAD.Pro is a general purpose structural analysis and design program withapplications primarily in the building industry - commercial buildings, bridges andhighway structures, industrial structures, chemical plant structures, dams,retaining walls, turbine foundations, culverts and other embedded structures, etc.The program hence consists of the following facilities to enable this task.

1. Graphical model generation utilities as well as text editor based commandsfor creating the mathematical model. Beam and column members arerepresented using lines. Walls, slabs and panel type entities are representedusing triangular and quadrilateral finite elements. Solid blocks arerepresented using brick elements. These utilities allow the user to create thegeometry, assign properties, orient cross sections as desired, assignmaterials like steel, concrete, timber, aluminum, specify supports, applyloads explicitly as well as have the program generate loads, designparameters etc.

2. Analysis engines for performing linear elastic and pdelta analysis, finiteelement analysis, frequency extraction, and dynamic response (spectrum,time history, steady state, etc.).

3. Design engines for code checking and optimization of steel, aluminum andtimber members. Reinforcement calculations for concrete beams, columns,slabs and shear walls. Design of shear and moment connections for steelmembers.

4. Result viewing, result verification and report generation tools for examiningdisplacement diagrams, bending moment and shear force diagrams, beam,plate and solid stress contours, etc.

5. Peripheral tools for activities like import and export of data from and to otherwidely accepted formats, links with other popular softwares for niche areaslike reinforced and prestressed concrete slab design, footing design, steelconnection design, etc.

6. A library of exposed functions called OpenSTAAD which allows users toaccess STAAD.Pro’s internal functions and routines as well as its graphicalcommands to tap into STAAD’s database and link input and output data tothird-party software written using languages like C, C++, VB, VBA,

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FORTRAN, Java, Delphi, etc. Thus, OpenSTAAD allows users to link in-houseor third-party applications with STAAD.Pro.

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About the STAAD.Pro DocumentationThe documentation for STAAD.Pro consists of a set of manuals as describedbelow. These manuals are normally provided only in the electronic format.

All the manuals can be accessed from the Help facilities of STAAD.Pro. If you wantto obtain a printed copy of the books, visit the docs.bentley.com site to checkavailability and order. Bentley also supplies the manuals in the PDF format at nocost for those who want to print them on their own. See the back cover of thisbook for addresses and phone numbers.

Getting Started and TutorialsThis manual contains information on the contents of the STAAD.Pro package, computer system requirements, installation process, copy protection issues and adescription on how to run the programs in the package. Tutorials that providedetailed and step-by-step explanation on using the programs are also provided.

Examples ManualThis book offers examples of various problems that can be solved using theSTAAD engine. The examples represent various structural analyses and designproblems commonly encountered by structural engineers.

Graphical EnvironmentThis document contains a detailed description of the Graphical User Interface(GUI) of STAAD.Pro. The topics covered include model generation, structuralanalysis and design, result verification, and report generation.

Technical Reference ManualThis manual deals with the theory behind the engineering calculations made by theSTAAD engine. It also includes an explanation of the commands available in theSTAAD command file.

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International Design CodesThis document contains information on the various Concrete, Steel, and Aluminumdesign codes, of several countries, that are implemented in STAAD.

The documentation for the STAAD.Pro Extension component(s) is availableseparately.

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Section 1

Australian Codes

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Australian Codes - Concrete Design per AS3600 - 2001

1A.1 Design Operations

STAAD has the capabilities for performing concrete design based on the Australiancode AS 3600-2001 Australian Standard-Concrete Structures.

1A.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be designed.

l For Beams: Prismatic (Rectangular & Square)

l For Columns: Prismatic (Rectangular, Square, and Circular)

1A.3 Member Dimensions

Concrete members which will be designed by the programmust have certainsection properties input under the MEMBER PROPERTY command. The followingexample shows the required input:

UNIT MM

MEMBER PROPERTY

1 3 TO 7 9 PRISM YD 450. ZD 250.

11 13 PR YD 350.

In the above input, the first set of members are rectangular (450 mm depth and250mmwidth) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with 350 mm diameter. It is absolutelyimperative that the user not provide the cross section area (AX) as an input.

1A.4 Design Parameters

The program contains a number of parameters which are needed to perform thedesign. Default parameter values have been selected such that they are frequentlyused numbers for conventional design requirements. These values may be changedto suit the particular design being performed. Table 1A.1 of this manual contains acomplete list of the available parameters and their  default values. It is necessary to

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declare length and force units as Millimeter and Newton before performing theconcrete design.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

Parameter Name Default Value Description

CODE - Must be specified asAUSTRALIAN to invokesdesign per AS 3600 -2001.

Design Code to follow.

See section 5.52.2 of theTechnical ReferenceManual.

CLEAR 25 mm

40 mm

For beammembers.

For column members

DEPTH YD Total depth to be usedfor design. This valuedefaults to YD asprovided under MEMBERPROPERTIES.

Table 1A.1 - Australian Concrete Design per AS 3600 Parameters

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Parameter Name Default Value Description

FMC 40 N/mm2 Concrete Yield Stress.Applicable values perClause 6.1.1.1 of AS3600-2001:

20

25

32

40

50

65

FYMAIN 450 N/mm2 Yield Stress for mainreinforcing steel.Applicable values perTable 6.2.1 of AS 3600-2001:

250

400

450

500

FYSEC 450 N/mm2 Yield Stress forsecondary reinforcingsteel. Applicable valuesper Table 6.2.1 of AS3600-2001:

250

400

450

500

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Parameter Name Default Value Description

MAXMAIN 60 mm Maximummainreinforcement bar size.

MINMAIN 10 mm Minimummainreinforcement bar size.

MAXSEC 12 mm Maximum secondaryreinforcement bar size.

MINSEC 8 mm Minimum secondaryreinforcement bar size.

RATIO 4.0 Maximum percentage oflongitudinalreinforcement incolumns.

REINF 0.0 Tied column. A value of1.0 will mean spiralreinforcement.

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Parameter Name Default Value Description

TRACK 0.0 BEAM DESIGN:

For TRACK =0.0, outputconsists ofreinforcementdetails atSTART,MIDDLE andEND.

For TRACK =1.0, criticalmoments areprinted inaddition toTRACK 0.0output.

For TRACK =2.0, requiredsteel forintermediatesectionsdefined byNSECTIONare printed inaddition toTRACK 1.0output.

COLUMN DESIGN:

With TRACK= 0.0,reinforcementdetails areprinted.

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Parameter Name Default Value Description

WIDTH ZD Width to be used fordesign. This valuedefaults to ZD asprovided under MEMBERPROPERTIES.

1A.5 Slenderness Effects and Analysis Con-sideration

Slenderness effects are extremely important in designing compression members.There are two options by which the slenderness effect can be accommodated. Oneoption is to perform an exact analysis which will take into account the influence ofaxial loads and variable moment of inertia on member stiffness and fixed endmoments, the effect of deflections on moment and forces and the effect of theduration of loads. Another option is to approximately magnify design moments.

STAAD has been written to allow the use of the first option. To perform this typeof analysis, use the command PDELTA ANALYSIS instead of PERFORM ANALYSIS.The PDELTA ANALYSIS will accommodate the requirements of the second- orderanalysis described by AS 3600, except for the effects of the duration of the loads.It is felt that this effect may be safely ignored because experts believe that theeffects of the duration of loads are negligible in a normal structural configuration.

Although ignoring load duration effects is somewhat of an approximation, it mustbe realized that the evaluation of slenderness effects is also by an approximatemethod. In this method, additional moments are calculated based on empiricalformula and assumptions on sidesway.

Considering all of the above information, a PDELTA ANALYSIS, as performed bySTAAD may be used for the design of concrete members. However the user mustnote that to take advantage of this analysis, all the combinations of loading mustbe provided as primary load cases and not as load combinations. This is due to thefact that load combinations are just algebraic combinations of forces andmoments, whereas a primary load case is revised during the P-delta analysis basedon the deflections. Also, note that the proper factored loads (like 1.5 for dead loadetc.) should be provided by the user. STAAD does not factor the loadsautomatically.

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1A.6 Beam Design

Beams are designed for flexure, shear and torsion. For all these forces, all activebeam loadings are prescanned to identify the critical load cases at different sectionsof the beams. The total number of sections considered is 13 (e.g., 0., .1, .2, .25, .3,.4, .5, .6, .7, .75, .8, .9, and 1). All of these sections  are scanned to determine thedesign force envelopes.

Design  for  Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) andhogging (creating tensile stress at the top face) moments are calculated for allactive load cases at each of the above mentioned sections. Each of these sections isdesigned to resist both of these critical sagging and hogging moments. Currently,design of singly reinforced sections only is permitted. If the section dimensions areinadequate as a singly reinforced section, such a message will be permitted in theoutput. Flexural design of beams is performed in two passes. In the first pass,effective depths of the sections are determined with the assumption of single layerof assumed reinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database in singleor multiple layers. The entire flexure design is performed again in a second passtaking into account the changed effective depths of sections calculated on the basisof reinforcement provided after the preliminary design. Final provisions of flexuralreinforcements are made then. Efforts have been made to meet the guideline forthe curtailment of reinforcements as per AS 3600. Although  exact curtailmentlengths are not mentioned explicitly in the design output (finally which will be moreor less guided by the detailer taking into account of other practical consideration),user has the choice of printing reinforcements provided by STAAD at 13 equallyspaced sections from which the final detailed drawing can be prepared.

Design for Shear

Shear reinforcement is calculated to resist both shear forces and torsionalmoments. Shear design is performed at 13 equally spaced sections (0. to 1.) for themaximum shear forces amongst the active load cases and the associated torsionalmoments. Shear capacity calculation at different sections without the shearreinforcement is based on the actual tensile reinforcement provided by STAAD.Two-legged stirrups are provided to take care of the balance shear forces acting onthese sections.

Example of Input Data for Beam Design:

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UNIT NEWTON MMS

START CONCRETEDESIGN

CODE AUSTRALIAN

FYMAIN 415 ALL

FYSEC 415 ALL

FC 35 ALL

CLEAR 25 MEM2 TO6

MAXMAIN 40 MEMB 2 TO 6

TRACK 1.0 MEMB 2 TO 9

DESIGN BEAM 2 TO9

END CONCRETEDESIGN

1A.7 Column Design

Columns are designed for axial forces and biaxial moments at the ends. All activeload cases are tested to calculate reinforcement. The loading which yieldsmaximum reinforcement is called the critical load. Column design is done forsquare, rectangular and circular sections. By default, square and rectangularcolumns are designed with reinforcement distributed on each side equally. Thatmeans the total number of bars will always be a multiple of four (4). This maycause slightly conservative  results in some cases. All major criteria for selectinglongitudinal and transverse reinforcement as stipulated by AS 3600 have beentaken care of in the column design of STAAD.

Example of Input Data for Column Design:

UNIT NEWTON MMS

START CONCRETEDESIGN

CODE AUSTRALIAN

FYMAIN 415 ALL

FC 35 ALL

CLEAR 25 MEMB 2 TO 6

MAXMAIN 40 MEMB 2 TO 6

DESIGN COLUMN 2 TO6

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END CONCRETEDESIGN

1A.8 Slab/Wall Design

To design a slab or wall, it must be modeled using finite elements. The commandspecifications are in accordance with Chapter 2 and Chapter 6 of the specification.

Elements are designed for the moments Mx and My. These moments are obtainedfrom the element force output (see Section 3.8 of the Technical Reference Manual).The reinforcement required to resist Mx moment is denoted as longitudinalreinforcement and the reinforcement required to resist My moment is denoted astransverse reinforcement. The parameters FYMAIN, FC, MAXMAIN, MINMAIN, andCLEAR listed in Table 1A.1 are relevant to slab design. Other parameters mentionedin Table 1A.1 are not applicable to slab design.

Figure 1.1 - Element moments: Longitudinal (L) and Transverse (T)

Example of Input Data for Slab/Wall Design

UNIT NEWTON MMS

START CONCRETEDESIGN

CODE AUSTRALIAN

FYMAIN 415 ALL

FC 25 ALL

CLEAR 40 ALL

DESIGN ELEMENT 15 TO 20

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END CONCRETEDESIGN

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Australian Codes - Steel Design per AS 4100 -1998

1B.1 General

This section presents some general statements regarding the implementation of thespecifications recommended by Standards Australia for structural steel design (AS4100 - 1998 Steel Structures) in STAAD. The design philosophy and procedurallogistics are based on the principles of elastic analysis and limit state method ofdesign. Facilities are available for member selection as well as code checking.

The design philosophy embodied in this specification is based on the concept oflimit state design. Structures are designed and proportioned taking intoconsideration the limit states at which they would become unfit for their intendeduse. Two major categories of limit-state are recognized - ultimate andserviceability. The primary considerations in ultimate limit state design are strengthand stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all steelstructures under various loading conditions and at the same time the chances oflimits being surpassed are acceptably remote.

In the STAAD implementation, members are proportioned to resist the design loadswithout exceeding the limit states of strength, stability, and serviceability.Accordingly, the most economic section is selected on the basis of the least weightcriteria as augmented by the designer in specification of allowable member depths,desired section type, or other such parameters. The code checking portion of theprogram checks whether code requirements for each selected section are met andidentifies the governing criteria.

The following sections describe the salient features of the STAAD implementationof AS 4100. A detailed description of the design process along with its underlyingconcepts and assumptions is available in the specification document.

Strength Limit States

Strength design capacities (φRu) are calculated and compared to user-defineddesign action effects (S*), so as to ensure that S* ≤ φRu in accordance with AS4100 3.4. Details for design capacity calculations are outlined in the sections thatfollow.

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Deflection Limit States

STAAD.Pro’s AS 4100 implementation does not generally check deflections. It isleft to the user to check that both local member and frame deflections are withinacceptable limits.

Note: Local member deflections parallel to the local member y-axis can bechecked against a user-defined maximum “span / deflection” ratio. This can beperformed using the DFF, DJ1, and DJ2 design parameters, however this isonly available for MEMBER Design. Details are provided in the sections thatfollow.

Eccentric Beam Reactions

STAAD.Pro does not automatically account for minimum eccentricity distances forbeam reactions being transferred to columns as per AS 4100 4.3.4. Howevermember offsets can be used to model these eccentricities.

Refer to Section 5.25 for further information on the Member Offset feature.

Limit States Not Considered

The following limit states are not directly considered in STAAD.Pro’simplementation of AS 4100.

Limit State Code Ref-erence

Stability AS 41003.3

Serviceability AS 41003.5

Brittle Fracture AS 41003.7

Fire AS 4100

Table 1B.1 - Limit States Not Con-sidered in STAAD.Pro AS 4100

Design

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Limit State Code Ref-erence

3.9

Other DesignRequirements

AS 41003.11

Connection Design

STAAD.Pro and Bentley’s RAM Connection program currently do not supportdesign of connections in accordance with AS 4100. In some cases connectiondesign may govern the size of members. Such considerations are not considered inSTAAD.Pro’s AS 4100 and should be checked by separately.

Bolts and Welds

Bolt holes and welds are not generally considered in STAAD.Pro’s AS 4100 memberdesign.

Note: NSC and NSF design parameters are used to manually specify a reductionin net section area for compression or tension capacity calculations. These canbe used to account for bolt hole area reductions. Further details are provided inthe sections that follow.

1B.2 Analysis Methodology

Either the elastic or dynamic analysis methods may be used to obtain the forces andmoments for design as per AS 4100 section 4.4. Analysis is done for the specifiedprimary and repeat loading conditions. Therefore, it is your responsibility to enterall necessary loads and load combination factors for design in accordance with theAS/NZS 1170 Series or other relevant design codes. You are allowed completeflexibility in providing loading specifications and using appropriate load factors tocreate necessary loading situations. Depending upon the analysis requirements,regular stiffness analysis or P-Delta analysis may be specified. Dynamic analysismay also be performed and the results combined with static analysis results.

Note: Plastic analysis and design in accordance with AS 4100 section 4.5 is notimplemented in STAAD.Pro.

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Elastic Analysis

Two types of elastic analysis can be performed using STAAD.Pro in accordancewith AS 4100:

i. First Order Linear, Elastic Analysis - used to perform a regular elastic stiff-ness analysis as per AS 4100 4.4.2.1. Refer to Section 5.37.1 of the Tech-nical Reference Manual for additional details on this feature.

ii. Second Order PDelta Linear, Elastic Analysis - Depending on the type ofstructure, a PDelta analysis may be required in order to capture second-order effects as per AS 4100 4.4.1.2. Second-order effects can be capturedin STAAD.Pro by performing a PDelta second-order elastic analysis as per AS4100 Appendix E. Refer to Section 5.37.2 of the Technical Reference Manualfor additional details on this feature.

Note: Moment amplification as per AS 4100 clause 4.4.2 is notconsidered.

Hint: In order to correctly capture second-order effects for combinationload cases using a PDelta Analysis, the Repeat Load feature must beused. Second-order effects will not be correctly evaluated if the LoadCombination feature is used. Load Combinations are combinations ofresults where Repeat Loads instruct the program to perform the analysison the combined load actions. Refer to Section 5.32.11 of the TechnicalReference Manual for additional details on using Repeat Loads.

Dynamic Analysis

Dynamic analysis may also be performed and the results combined with staticanalysis results. Refer Section 5.32.10 of the Technical Reference Manual forfurther information on Dynamic Loading and Analysis features.

1B.3 Member Property Specifications

For specification of member properties, either the steel section library available inSTAAD or the User Table facility may be used. The next section describes thesyntax of commands used to assign properties from the built-in steel table. For

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more information on these facilities, refer to Section 1.7 the STAAD TechnicalReference Manual.

1B.4 Built-in Steel Section Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, the properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredduring the analysis of these members. An example of the member propertyspecification in an input file is provided at the end of this section.

A complete listing of the sections available in the built-in steel section library maybe obtained by using the tools of the graphical user interface.

Refer to Section 1.7.2 of the Technical Reference Manual for additional information.

General ProfileType

Australian Sec-tions

Description

I-SECTION WB, WC Welded beams and columns

UB, UC Universal beams and columns

T-SECTION BT, CT Tees cut from universal beams and col-umns

CHANNEL PFC Parallel flange channels

ANGLE EA, UA Equal and unequal angles

TUBE SHS, RHS Square and rectangular hollow sec-tions

PIPE CHS Circular hollow sections

Table 1B.2 - Available Australian Sections for STAAD.Pro AS 4100 Design

Note: STAAD.Pro will not design the following section types to AS 4100:Double Profiles (D), Composite Sections (C), Top Cover Plates (TC), BottomCover Plates (BC), and Top & Bottom Cover Plates (TB), Double Channels (D,BA, & FR) and Double Angles (LD & SD). Refer to Section Profile Tables in theGraphical Environment for these options.

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Hint: When adding and assigning sections using the built-in steel sectionlibrary through the Graphical Environment, STAAD.Pro’s default tables areAmerican. To change the default tables to Australian, select File >Configuration from the STAAD.Pro Start page (no input file open). Set theDefault Profile Table to Australian on the Configure Program dialog SectionProfile Table.

Following are the descriptions of different types of sections.

UB Shapes

These shapes are designated in the following way.

20 TO 30 TA ST UB150X14.0

36 TO 46 TA ST UB180X16.1

UC Shapes

The designation for the UC shapes is similar to that for the UB shapes.

25 TO 35 TA ST UC100X14.8

23 56 TA ST UC310X96.8

Welded Beams

Welded Beams are designated in the following way.

25 TO 35 TA ST WB700X115

23 56 TA ST WB1200X455

Welded Columns

Welded Columns are designated in the following way.

25 TO 35 TA ST WC400X114

23 56 TA ST WC400X303

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Parallel Flange Channels

Shown below is the syntax for assigning names of channel sections.

1 TO 5 TA ST PFC75

6 TO 10 TA ST PFC380 

Double Channels

Back-to-back double channels, with or without a spacing between them, areavailable. The letter D in front of the section name will specify a double channel.

11 TA D PFC230

17 TA D C230X75X25 SP 0.5

In the above set of commands, member 11 is a back-to-back double channelPFC230 with no spacing in between. Member 17 is a double channel PFC300 with aspacing of 0.5 length units between the channels.

Angles

Two types of specification may be used to describe an angle. The standard anglesection is specified as follows:

16 20 TA ST A30X30X6

The above section signifies an angle with legs of length 30 mm and a leg thicknessof 6 mm. This specification may be used when the local Z axis corresponds to the z-z axis specified in Chapter 2. If the local Y axis corresponds to the z-z axis, typespecification "RA" (reverse angle) may be used.

17 21 TA RA A150X150X16

Note: Single angles must be specified with an “RA” (Single Angle w/Reverse Y-Z Axis) in order to be designed to AS 4100. This is to ensure that the major andminor principal axes align with the local member z and y axes respectively,similar to other section profiles.

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Double Angles

Short leg back-to-back or long leg back-to-back double angles can be specified bymeans of input of the words SD or LD, respectively, in front of the angle size. Incase of an equal angle, either SD or LD will serve the purpose.

33 35 TA SD A65X50X5 SP 0.6

37 39 TA LD A75X50X6

43 TO 47 TA LD A100X75X10 SP 0.75

Tubes (Rectangular or Square Hollow Sections)

Tubes can be assigned in 2 ways. In the first method, the designation for the tubeis as shown below. This method is meant for tubes whose property name isavailable in the steel table. In these examples, members 1 to 5 consist of a2X2X0.5 inch size tube section, and members 6 to 10 consist of 10X5X0.1875 inchsize tube section. The name is obtained as 10 times the depth, 10 times the width,and 16 times the thickness.

1 TO 5 TA ST TUB20202.5

6 TO 10 TA ST TUB100503.0

In the second method, tubes are specified by their dimensions. For example,

6 TA ST TUBEDT 8.0WT 6.0 TH 0.5

is a tube that has a height of 8 length units, width of 6 length units, and a wallthickness of 0.5 length units. Only code checking, no member selection, will beperformed for TUBE sections specified in this latter manner.

Pipes (Circular Hollow Sections)

Pipes can be assigned in 2 ways. In the first method, the designation for the pipeis as shown below. This method is meant for pipes whose property name isavailable in the steel table.

1 TO 5 TA ST PIP180X5

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6 TO 10 TA ST PIP273X6.5

In the second method, pipe sections may be provided by specifying the word PIPEfollowed by the outside and inside diameters of the section. For example,

1 TO 9 TA ST PIPE OD 25.0 ID 20.0

specifies a pipe with outside diameter of 25 length units and inside diameter of 20length units. Only code checking, no member selection, will be performed on pipesspecified in this latter manner.

Sample File Containing Australian Shapes

STAAD SPACE

UNIT METER KN

JOINT COORD

1 0 0 0 11 100 0 0

MEMB INCI

1 1 2 10

UNIT CM

MEMBER PROPERTIES AUSTRALIAN

* UB SHAPES

1 TA ST UB200X25.4

* UC SHAPES

2 TA ST UC250X89.5

* CHANNELS

3 TA ST PFC125

* DOUBLE CHANNELS

4 TA D PFC200

* ANGLES

5 TA ST A30X30X6

* REVERSE ANGLES

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6 TA RA A150X150X16

* DOUBLE ANGLES - SHORT LEGS BACK TOBACK

7 TA SD A65X50X5 SP 0.6

* DOUBLE ANGLES - LONG LEGS BACK TOBACK

8 TA LD A100X75X10 SP 0.75

* TUBES (RECTANGULAROR SQUAREHOLLOWSECTIONS)

9 TA ST TUBEDT 8.0WT 6.0 TH 0.5

* PIPES (CIRCULAR HOLLOWSECTIONS)

10 TA ST PIPE OD 25.0 ID 20.0

PRINT MEMB PROP

FINISH

1B.5 Section Classification

The AS 4100 specification allows inelastic deformation of section elements. Thus,local buckling becomes an important criterion. Steel sections are classified ascompact, noncompact, or slender; depending upon their local bucklingcharacteristics. This classification is a function of the geometric properties of thesection. The design procedures are different depending on the section class.STAAD determines the section classification for the standard shapes and userspecified shapes. Design is performed for all three categories of section describedabove.

1B.6 Material Properties

For specification of material properties, the user can use either:

a. built-in material constants

b. user-defined materials

Refer Section 5.26.2 of the Technical Reference Manual for further information onthe Built-in Material Constants feature.

Refer Section 2.26.1 of the Technical Reference Manual for further information onthe Define Material feature.

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Young’s Modulus of Elasticity (E)

STAAD.Pro’s default steel material’s E value is 205,000 MPa. However AS 4100section 1.4 states that the modulus of elasticity should be taken as 200,000 MPa.There are a number of options to change this value:

l change the steel material through the input file or GUI for each file created

l define a new steel material for each file created

l change the default STAAD.Pro metric E value in the fileC:/WINDOWS/STAADPRO20070.INI, going to the “[Material-Metric]” section,and changing E1=205.0e6 to E1=200.0e6. Restart STAAD.Pro for this totake effect.

Warning: Virtualization features of Windows Vista and Windows 7 mayrequire additional files to be modified. Contact Bentley Technical Supportfor assistance.

1B.7 Member Resistances

The member resistance is calculated in STAAD according to the procedures outlinedin AS 4100. Calculated design capacities are compared to corresponding axial,bending moment, and shear forces determined from the STAAD.Pro analysis. Theseare used to report the fail or pass status for the members designed.

Two types of design checks are typically performed per AS 4100:

l Nominal section checks

l Nominal member checks

The nominal section capacity refers to the capacity of a cross-section to resistsapplied loads, and accounts for cross-section yielding and local buckling effects.The nominal member capacity on the other hand refers to the capacity of a memberto resist applied loads, and includes checks for global member buckling effectsincluding Euler buckling, lateral-torsional buckling, etc.

Axial Tension

The criteria governing the capacity of tension members are based on two limitstates per AS 4100 Section 7. The limit state of yielding of the gross section is

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intended to prevent excessive elongation of the member.

The second limit state involves fracture at the section with the minimum effectivenet area φN

tsection axial tension capacities are calculated (Cl.7.2). Through the

use of the NSF parameter (see Table 1B.1), you may specify the net section area.STAAD calculates the tension capacity of a member based on these two limit statesper Cl.7.1 and Cl.7.2 respectively of AS 4100. Eccentric end connections can betaken into account using the KT correction factor, perCl.7.3. The f

yyield stress is

based on the minimum plate yield stress. Parameters FYLD, FU, and NSF areapplicable for these calculations.

Axial Compression

The compressive strength of members is based on limit states per AS 4100 Section6. It is taken as the lesser of  nominal section capacity and nominal membercapacity. Nominal section capacity, φN

s, is a function of form factor (Cl.6.2.2), net

area of the cross section, and yield stress of the material. Through the use of theNSC parameter (see Table 1B.1), you may specify the net section area. Note thatthis parameter is different from that corresponding to tension. The programautomatically calculates the form factor. The k

fform factors are calculated based

on effective plate widths per Cl.6.2.4, and the fyyield stress is based on the

minimum plate yield stress.

Nominal member capacity, φNc, is a function of nominal section capacity and

member slenderness reduction factor (Cl.6.3.3). This value is calculated aboutboth principal x and y axes. Here, you are required to supply the value of α

b(Cl.6.3.3) through the ALB parameter (see Table 1B.1). The effective length for thecalculation of compressive strength may be provided through the use of theparameters KY, KZ, LY, and LZ (see Table 1B.1).

Bending

Bending capacities are calculated to AS 4100 Section 5. The allowable bendingmoment of members is determined as the lesser of nominal section capacity andnominal member capacity (ref. Cl.5.1). 

The nominal section moment capacity, φMs, is calculated about both principal x

and y axes and is the capacity to resist cross-section yielding or local buckling andis expressed as the product of the yield stress of the material and the effectivesection modulus (ref. Cl.5.2). The effective section modulus is a function of sectiontype (i.e., compact, noncompact, or slender) and minimum plate yield stress f

y.

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The nominal member capacity depends on overall flexural-torsional buckling of themember (ref.Cl.5.3).

Note: For sections where the web and flange yield stresses (fy,web

and fy.flange

respectively) are different, the lower of the two yield stresses is applied to boththe web and flange to determine the slenderness of these elements.

Member moment capacity, φMb, is calculated about the principal x axis only (ref.

Cl.5.6). Critical flange effective cross-section restraints and corresponding designsegment and sub-segments are used as the basis for calculating capacities.

Interaction of Axial Force and Bending

Combined section bending and shear capacities are calculated using the shear andbending interaction method as per Cl.5.12.3.

Note: This check is only carried out where φVvsection web shear capacities are

calculated. Refer Table 1B.6-1 for details.

The member strength for sections subjected to axial compression and uniaxial orbiaxial bending is obtained through the use of interaction equations. Here, theadequacy of a member is also examined against both section (ref. Cl.8.3.4) andmember capacity (ref.Cl.8.4.5). These account for both in-plane and out-of-planefailures. If the summation of the left hand side of the equations, addressed by theabove clauses, exceeds 1.0 or the allowable value provided using the RATIOparameter (see Table 1B.1), the member is considered to have FAILed under theloading condition.

Shear

Section web shear capacity, φVv, is calculated per Cl.5.11, including both shear

yield and shear buckling capacities. Once the capacity is obtained, the ratio of theshear force acting on the cross section to the shear capacity of the section iscalculated. If any of the ratios (for both local Y & Z-axes) exceed 1.0 or theallowable value provided using the RATIO parameter (see Table 1B.1), the sectionis considered to have failed under shear.

Table 1B.6-1 below highlights which shear capacities are calculated for differentprofile types.

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General Profile Type AustralianSection

Shear Checks

I-SECTION

(i.e., parallel to minorprincipal y-axis)

WB, WC, UB,UC

Calculated for web only

T-SECTION BT, CT

CHANNEL PFC

ANGLE EA, UA No checks performed

TUBE SHS, RHS Calculated parallel to both x & yprincipal axes

PIPE CHS Per AS 4100 5.11.4

Table 1B.3 - Section Type Shear Checks

Note: Only unstiffened web capacities are calculated. Stiffened webs are notconsidered. Bearing capacities are not considered.

Torsion

STAAD.Pro does not design sections or members for torsion for AS 4100.

1B.8 Design Parameters

The design parameters outlined in Table 1B.1 are used to control the designprocedure. These parameters communicate design decisions from the engineer tothe program and thus allow the engineer to control the design process to suit anapplication's specific needs. The design scope indicates whether designparameters are applicable for MEMBER Design, PMEMBER Design, or both.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements, some or all of these parameter values may be changed to exactlymodel the physical structure. 

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

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ParameterName

Default Value DesignScope

Description

CODE - Must be specified asAUSTRALIAN toinvoke design perAS 4100 - 1998.

Design Code tofollow. See section5.48.1 of theTechnical ReferenceManual.

ALB 0.0 Member sectionconstant (refer cl.6.3.3)

If ALB is 0.0, it isautomaticallycalculated based onTABLE 6.3.3(1),6.3.3(2); otherwisethe input value isused.

ALM 0.0 Momentmodification factor(refer cl. 5.6.1.1)

If ALM is 0.0, it isautomaticallycalculated basedcl.5.6.1.1; otherwisethe input value isused.

BEAM 0.0 0.0  =  design onlyfor end momentsand those atlocations specifiedby SECTION

Table 1B.4 - Australian Steel Design Parameters

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ParameterName

Default Value DesignScope

Description

command.

1.0  =  Performdesign for moments at twelfth pointsalong the beam.

DFF None (Mandatoryfor  deflection

check)

Analyticalmembersonly

“Deflection Length”/Maximum Allowablelocal deflection.

DJ1 Start Joint ofmember

Joint No. denotingstart point forcalculation of“deflection length”

DJ2 End Joint ofmember

Joint No. denotingend point forcalculation of“deflection length”

DMAX 45.0 [in.] Maximum allowabledepth (Applicablefor memberselection)

DMIN 0.0 [in.] Minimum requireddepth (Applicablefor memberselection)

EEC 0.0 Physicalmembersonly

Used to specify thetype of end con-nection to accountfor eccentric con-nection effects forcompression and ten-sion members.

IST 1 Steel type -  1 - SR,2 - HR, 3 - CF, 4 -

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ParameterName

Default Value DesignScope

Description

LW, 5 - HW

FU 500.0 [MPa] Ultimate strength ofsteel.

FYLD 250.0 [MPa] Yield strength ofsteel.

KT 1.0 Correction factor fordistribution of forces(refer cl. 7.2)

KY 1.0 K value for generalcolumn flexuralbuckling about thelocal Y-axis. Used tocalculateslenderness ratio.

KZ 1.0 K value for generalcolumn flexuralbuckling about thelocal Z-axis. Used tocalculateslenderness ratio.

LHT 0 Physicalmembersonly

Load height positionas described in Table5.6.3(2) of AS4100:1998

0 = atShearcenter

1 = Attopflange

LY Member Length Length for generalcolumn flexural

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ParameterName

Default Value DesignScope

Description

buckling about thelocal Y-axis. Used tocalculateslenderness ratio.

LZ Member Length Length for generalcolumn flexuralbuckling about thelocal Z-axis. Used tocalculateslenderness ratio.

MAIN 0.0 0.0  =  Checkslenderness ratioagainst the limits.

l Default limitfor com-pression =180.0  

l Default limit intension =400.0

1.0 = Suppress theslenderness ratiocheck.

Any value greaterthan 1.0 is used asthe limit forslenderness incompression.

NSC 1.0 Net section factor forcompressionmembers = An / Ag

(refer cl. 6.2.1)

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ParameterName

Default Value DesignScope

Description

NSF 1.0 Net section factor fortension members.

PBRACE None Physicalmembersonly

Refer to section1B.11 for details onthe PBRACE param-eter.

PHI 0.9 Capacity reductionfactor

RATIO 1.0 Permissible ratio ofactual load effect tothe design strength.

SGR 0 Steel Grade. Refer toNote a below.

0 =Normalgrade

1 = Highstrengthgrade ofsteel

SKT 1.0 A twist restraint fac-tor given in Table5.6.3(1)

SKL 1.0 A load height factorgiven in Table5.6.3(2)

SKR 1.0 A lateral rotationrestraint factor givenin Table 5.6.3(3)

TEE 0.0 Physicalmembersonly

Used to specifywhether eccentric

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ParameterName

Default Value DesignScope

Description

effects for tensionmembers arechecked based onsimplified kt cor-rections factors toAS 4100 7.3.2, or byusing calculatedeccentric momentsin combination withaxial tension per AS4100 Section 8.

TMAIN 180.0 Slenderness limit intension. Slendernesslimit is checkedbased MAIN param-eter.

TRACK 0.0 Output detail

0.0 =Reportonlyminimumdesignresults.

1.0 =Reportdesignstrengthsalso.

2.0 =Providefulldetails ofdesign.

UNB Member Length Unsupported length

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ParameterName

Default Value DesignScope

Description

in bendingcompression of thebottom flange forcalculating momentresistance.

UNT Member Length Unsupported lengthin bendingcompression of thetop flange forcalculating momentresistance.

Notes

a. Deflection calculations

b. LHT Parameter

If the shear force is constant within the segment, longitudinal position of theload is assumed to be at the segment end.

If there is any variation of the shear force and the load is acting downwarddetermined from shear force variation and load height parameter indicatesthe load is acting on top flange (flange at the positive local y axis) andrestraints at the end of the segment is not FU (FRU) or PU (PRU) Kl is assumedto be 1.4.

If there is any variation of the shear force and the load is acting upwarddetermined from shear force variation and load height parameter indicatesthe load is acting on top flange (flange at the positive local y axis) andrestraints at the end of the segment is not FU (FRU) or PU (PRU) Kl is assumedto be 1.0 as the load acting at the top flange is contributing to stabilizeagainst local torsional buckling.

c. SGR Parameter

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AS 4100 defines the values of steel grades that are used as either normalsteel or high grade steel. The following table explains the material valuesused when either option is specified for a particular shape:

Section Type SGR Value SteelGradeUsed

WB, WC, Tee section cut fromWBand WC WB, WC, Tee section cutfromWB and WC

0 (Normal) 300

1 (High) 400

UB, UC, Tee section cut from UB andUC, EA, UA and all UPT sections UB,UC, Tee section cut from UB and UC,EA, UA and all UPT sections

0 (Normal) 300

1 (High) 350

Pipe, Tube, CHS, RHS, SHS Pipe,Tube, CHS, RHS, SHS

0 (Normal) 250

1 (High) 350

Table 1B.5 - Steel Grades used for the SGR Parameter

Note: If a value for the FYLD parameter has been specified, then thatvalue will be used. Otherwise, the SGR value will be used to determinethe yeild strength and tensile strength values for the steel. based onmaximum thickness of the individual elements of the section. Only forshear capacity calculation web thickness is used. Similarly, TensileStrength is determined either from FU parameter or from SGR parameter.

Warning: A check is introduced to see if yield stress is more than 450MPa or not. If it is, a warning is issued and the yield stress is set to 450MPa.

The following example uses the Member design facility in STAAD.Pro. However, itis strongly recommended to use the Physical member design capabilities forAS 4100:

PARAMETER 1

CODE AUSTRALIAN

ALB 0.0 MEMBER ALL

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ALM 1.13 MEMBER ALL

BEAM 1.0 MEMBER ALL

DFF 250.0 MEMBER ALL

DMAX 0.4 MEMBER ALL

DMIN 0.25 MEMBER ALL

FU 400.0 MEMBER ALL

FYLD 310.0 MEMBER ALL

IST 2.0 MEMBER ALL

KT 0.85 MEMBER ALL

KX 0.75 MEMBER ALL

KY 1.0 MEMBER ALL

LX 4.5 MEMBER ALL

LY 6.0 MEMBER ALL

MAIN 1.0 MEMBER ALL

TMAIN 135.0 MEMBER ALL

NSC 0.9 MEMBER ALL

NSF 1.0 MEMBER ALL

PHI 0.9 MEMBER ALL

RATIO 0.9 MEMBER ALL

SGR 1.0 MEMBER ALL

SKT 1.0 MEMBER ALL

SKL 1.0 MEMBER ALL

SKR 1.0 MEMBER ALL

TRACK 2.0 MEMBER ALL

UNB 3.4 MEMBER ALL

UNT 6.8 MEMBER ALL

CHECK CODEMEMBER ALL

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1B.9 Code Checking

The purpose of code checking is to evaluate whether the provided sectionproperties of the members are adequate for the specified loads as per AS 4100requirements.

Hint: The member selection facility can be used to instruct the program toselect a different section if the specified section is found to be inadequate.

Code checking for an analytical member is done using forces and moments atevery twelfth point along the beam. The code checking output labels the membersas PASSed or FAILed. In addition, the critical condition, governing load case,location (distance from the start joint) and magnitudes of the governing forces andmoments are also printed. The extent of detail of the output can be controlled byusing the TRACK parameter.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Example of commands for code checking:

UNIT NEWTON METER

PARAMETER

CODE AUSTRALIAN

FYLD 330E6 MEMB 3 4

NSF 0.85 ALL

KY 1.2 MEMB 3 4

RATIO 0.9 ALL

CHECK CODEMEMB 3 4                                  

Note: Code checking cannot be performed on composite and prismaticsections.

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Physical Members

For physical members (PMEMBERs), code checks are performed at section stationspositioned at 1/12th points along each analytical member included in the PMEMBER.It is up to you to determine if these locations cover critical sections for design, andadjust as necessary. The number of stations for PMEMBER Design cannot be altered,however the analytical members can be split so that in effect more stations arechecked for a PMEMBER.

For each section station along a PMEMBER, section capacity checks are carried fordesign actions at that station location. Member capacity checks are also carried outfor each station. For these the program searches each side of the station to findadjacent effective restraints and design forces and moments. This allows theprogram to determine the segment / sub-segment that the section station residesin, and then proceeds to calculate the member capacities. Enough section stationsshould be included to capture all segments / sub-segments for checking.

Note: When checking combined actions for the section capacities, the designactions at the section station are used. However when checking combinedactions for the member capacities, the maximum forces from anywhere alongthe segment / sub-segment being considered are used. This is as stipulated inAS 4100 8.2.

The output reports whether the member has PASSed or FAILed the design checks,as well as the critical condition, critical load case, magnitudes of design actions forthe most critical cross-section location (distance from the start joint), and completecalculations for design. The TRACK design parameter can be used to control thelevel of detail provided in the output. Color-coded results can also be viewed in theGUI’s Post Processing Beam | Unity Check page.

In some cases some of the output will report “N/A” values. This occurs where acalculation does not apply to a member. For example if a member never goes intotension then no values can be reported in the tension capacity output sections.

Note: As per AS 4100 1.4, the TRACK 2.0 detailed level of output forPMEMBER Design uses x and y subscripts to refer to major and minor principalaxes respectively. These differ to STAAD.Pro local member axes, where z and yrefer to major and minor principal axes.

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1B.10 Member Selection

This process incrementally checks increasing section profile sizes until a size isfound that is AS 4100 compliant, or the largest section has been checked. Onlysection profiles of the same type as modeled are incrementally checked, with theincreasing sizes based on a least weight per unit length criteria.

For example, a member specified initially as a channel will have a channel selectedfor it. Selection of members whose properties are originally provided from a usertable will be limited to sections in the user table.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

The design calculations for Member Selection are the same as for Code Checking.

Hint: A Fixed Group command is also available, and can be used to force allmembers within a user-defined group to take the same section size based onthe most critical governing design criteria for all members within that group.This is particularly useful when you want to use the Member Selection feature,but want a group of elements to have the same size. Refer to Section 5.49 ofthe Technical Reference Manual for information on using this feature.

Note: Member Selection will change member sizes, and hence will change thestructure’s stiffness matrix. In order to correctly account for this, a subsequentanalysis and Code Check should be performed to ensure that the final structureis acceptable. This may need to be carried out over several iterations.

Example of commands for member selection:

UNIT NEWTON METER

PARAMETER

FYLD 330E6 MEMB 3 4

NSF 0.85 ALL

KY 1.2 MEMB 3 4

RATIO 0.9 ALL

SELECT MEMB 3 4

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Note: Composite and prismatic sections cannot be selected.

1B.11 Tabulated Results of Steel Design

Results of code checking and member selection are presented in a tabular format.The term CRITICAL COND refers to the section of the AS 4100 specification whichgoverns the design.

1B.12 Physical Member Design

There are two methods available in STAAD.Pro for checking members against therequirements of AS 4100:

a. Analytical member method

b. Physical member method

Herein these are referred to as MEMBER Design and PMEMBER Design respectively.

Note: This feature requires STAAD.Pro V8i (SELECTseries 2) build 2007.07 orhigher.

Traditionally STAAD.Pro performed code checks based on single analyticalmembers (i.e., single members between two nodes). This implementation remainsin place as shown in the example in Section 1B.8. Physical Member (PMEMBER)Design on the other hand allows you to group single or multiple analyticalmembers into a single physical design member for the purposes of design to AS4100.

PMEMBER Design also has additional features, including:

l automated steel grades based on section type;

l automated tensile stress (fu) and yield stress (f

y) values based on plate thick-

nesses;

l automated segment / sub-segment design;

l improved detailed design calculation output; and

Thus, it is strongly recommended that PMEMBER Design be used, even for thedesign of single analytical members.

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Modeling with Physical Members

Physical Members may be grouped by either of the following methods:

l STAAD.Pro Editor - Directly specify physical members in the input file. Referto Section 5.16.2 of the Technical Reference Manual for additional infor-mation.

l Graphical Environment - Using the tools in the Steel Design toolbar,members can be manually or automatically formed. Refer to Section 1.4 ofthe Graphical Environment manual for additional information.

Note: When creating PMEMBERs for AS 4100, this must be performed inSTAAD.Pro’s Modeling mode. Do not use the Steel Design mode.

Segment and Sub-Segment Layout

For calculation of member bending capacities about the principal x-axis, thePMEMBER Design uses the concept of segment / sub-segment design. By defaultPMEMBERs are automatically broken up into design segments and sub-segmentsbased on calculated effective restraints. User-defined restraints assigned using thePBRACE design parameter are checked to see if they are effective (i.e., if they areplaced on the critical flange as per AS 4100 5.5). Restraints not applied to thecritical flange are ineffective and hence are completely ignored.

Refer to Section 1B.7 for further information on how user-defined restraints areapplied using the PBRACE design parameter, including available restraint types,and restraint layout rules.

Note: Segment and sub-segment layouts for PMEMBERs may change fordifferent load cases considered for design. Some restraints may be effective forone particular load case as they are found to apply to the critical flange,however for another load case may be found not to act on the critical flange,and found to be ineffective. In other words the critical flange can change foreach load case considered.

Typically the critical flange will be the compression flange, except for segmentswith a “U” restraint at one end, in which case it will be the tension flange (as is thecase for a cantilever).

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The PMEMBER Design uses the following routine to determine effective cross-section restraints for each load case considered:

i. first all user-defined restraints are checked to see if they are applied to thecompression flange, with those that aren’t ignored;

ii. next a check is made to see if a “U” type restraint is found at either end of thePMEMBER. If this is the case then any adjacent “L” restraints up to the next“F”, “FR”, “P” or “PR” restraint are also ignored, regardless of whether theyare placed on the critical or non-critical flange. Refer AS 4100 5.4.2.4.

The compression flange in step 1 of the routine above is calculated based on thebending moments at the locations of the restraints being considered. If the bendingmoment is zero at the same location as a restraint then the following method isused to determine which flange is critical at the zero moment location:

a. If the zero moment is at the end of the PMEMBER, then the compressionflange is based on the bending moment at a small increment from then end;

b. If the zero moment is along the PMEMBER and is a peak value, then the com-pression flange is based on the bending moment at a small increment fromthat location;

c. If neither 1 or 2 above is valid, then the stiffer of the restraints at that locationis taken. The stiffness of different restraint types from the most stiff to leaststiff are taken as outlined in Table 1B.9-3.

Stiffness Restraint Type

Most Stiff FR

F

PR

P

L

U

Least Stiff None

Table 1B.6 - Assumed Order ofRestraint Stiffness for ZeroMoment Critical Flange

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Once the effective restraints have been determined, the PMEMBER is divided intosegments bounded by “F”, “P”, “FR”, “PR” or “U” effective restraints. Thesesegments are then further divided into sub-segments by effective “L” restraints.

Note: Sub-segment lengths are not automatically checked to determine if theyprovide full lateral restraint as per AS 4100 5.3.2.4.

For design of cantilevers, the free tip should have user-defined “U” restraintsapplied to both top and bottom flanges.

Note: If the effective restraints for any load case consist of “U” or “L” restraintsonly, an error will be reported.

Physical Member Restraints Specification

The PBRACE parameter is used to specify the restraint condition along the top andbottom flange of a PMEMBER.

General Format

PBRACE { TOP | BOTTOM } f1 r1 f2 r2 … f52 r52 (PMEMB pmember-list)

Where:

fnis a fraction of the PMEMBER length where restraint condition is

being specified. This value is any ratio between 0.0 and 1.0.

rnis one of the possible restraint condition as in the following:

Designation,r1

RestraintType

Description

F Fullyrestrained

P Partiallyrestrained

Table 1B.7 - Physical Member Restraint Types

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Designation,r1

RestraintType

Description

L Laterallyrestrained

Cannot be specified atthe ends of designmembers.

U Unrestrained Can only be applied atthe ends of designmembers, and must beapplied to both flangesto be effective.

Warning: Both topand bottom flangescan not beunrestrained at thesame location (asthis is unstable).

FR Fully androtationallyrestrained

PR Partially androtationallyrestrained

C Continuouslyrestrained

The flange is assumedto be continuously sup-ported at that flange upto next restraint loca-tion. For continuouslysupported flangeunbraced length isassumed to be zero.

Example

PBRACE TOP 0.85 FR 0.33 PR 0.33 PR 0.25 F 0.75 L 0.5 PR 1.0 U 0.0

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U

PBRACE BOTTOM0.75 L 0.0 U 0.25 P 0.5 L -

1.0 U PMEMB 3 7

Description

Refer to AS 4100 Section 5.5 for a full definition of the critical flange. Typically thiswill be the compression flange, except for segments with U restraint at one end,then it will be the tension flange (as is the case for cantilever portion at the end).

l when gravity loads are dominant (i.e., negative local y-axis direction), thecritical flange of a segment shall be the top flange (i.e., tension).

l when upward wind loads are dominant (i.e., positive local y-axis direction),the critical flange shall be the bottom flange (i.e., tension).

Design physical members are divided into segments by “F”, “P”, “FR”, “PR” or “U”effective section restraints. Segments are further broken down into sub-segmentsby “L” restraints, but only if the “L” restraints are deemed to be “effective”. “L”restraints are only considered to be effective when positioned on the “critical”flange between “F”, “P”, “FR” or “FP” restraints. If an “L” restraint is positioned onthe non-critical flange it shall be completely ignored. Further, if an “L” restraint ispositioned between a “U” and an “F”, “P”, “FR” or “PR” restraint, it shall be ignored(regardless of whether it is on the critical or non-critical flange).

Design members must have either a F, P, FR, PR, or U restraint specified at bothends, for both flanges.

l If UNL is not specified, segment length is used as UNL and used as L in effec-tive length calculation as per 5.6.3.

l If ALM i.e., α_m is not provided, automatic calculation of ALM is done basedon moments within the segment.

l If SKR i.e., Kr is not provided, it is automatically calculated based on table5.6.3(3) considering restraint conditions are the end of the segment. If FR orPR is found at only one of the end, Kr is assumed to be 0.85; if FR or PR isfound at both the ends, 0.70 is used as Kr.

l If SKT i.e., Kt is not provided, it is automatically calculated based on Table5.6.3(1) considering end restraints of the segment and section geometricinformation and segment length.

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l If SKL i.e., Kl is not provided, it is automatically calculated based on Table5.6.3(2) considering end restraints of the segment, Load Height Positionparameter, LHT and shear force variation within the segment.

Notes

a. If PMEMBER list is not provided, all the PMEMBERS are restrained by sameconfiguration.

b. It is not necessary to provide the restraint locations in sequence as the pro-gram sorts them automatically.

c. Unless specified, PMEMBER ends are assumed to be Fully Restrained (F).

d. While designing any section of the member, effective restraints are searchedon each side of the section along the critical flange.

e. The types of restraints applied to the top and bottom flanges at each locationdetermines the effective section restraints. These are outlined in the tablebelow:

Case Flange Restrainton a Crit-icalFlange

Restrainton a Non-CriticalFlange

EffectiveSectionRestraint

I U U U

II 1 L Nothing L

2 Nothing L None

III 1 P or F Nothing orU

F

2 Nothing orU

P or F P

Table 1B.8 - Restraint Meanings in Critical and NoncriticalFlanges

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Case Flange Restrainton a Crit-icalFlange

Restrainton a Non-CriticalFlange

EffectiveSectionRestraint

IV 1 PR or FR Nothing orU

FR

2 Nothing orU

PR or FR PR

V 1 L, P or F L, P, F, FRor PR

F

2 FR or PR L, P, F, FRor PR

FR

Note: The critical flange can change for each load case considered.

Automated PMEMBER Design Calculations

The AS 4100 PMEMBER Design automates many design calculations, includingthose required for segment / sub-segment design.

AutomatedDesign Cal-culations

PMEMBERDesignParameter

Comments

αbcom-

pressionmember sec-tion constantper AS 41006.3.3.

ALB

αmmoment

modificationfactor per AS4100

ALM Calculated based on moments dis-tribution for individual segmentsand sub-segments.

Table 1B.9 - Automated PMEMBER AS 4100 Design Parametersand Calculations

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AutomatedDesign Cal-culations

PMEMBERDesignParameter

Comments

5.6.1.1.

futensile

strength perAS 41002.1.2.

FU Based on nominal steel grade spec-ified using SGR design parameterand section type.

fyyield stress

per AS 41002.1.1.

FYLD Based on nominal steel grade spec-ified using SGR design parameterand section type.

residualstress cat-egory for AS4100 Table5.2 and AS4100 Table6.2.4.

IST Based on section type.

correction fac-tor for dis-tribution offorces in atensionmember perAS 4100 7.3.

KT Based on section type and eccentricend connection specified using EECdesign parameter.

Load heightposition forautomatedcalculation ofthe kl loadheight factorper AS 4100Table5.6.3(2).

LHT LHT is used for automatingcalculation of kl load height factorsfor segments and sub-segments,per AS 4100 Table 5.6.3(2).

When LHT is set to 1.0 to specify atop flange load height position,STAAD.Pro takes the top to be thepositive local y-axis of the member.

Note: This may not literally be

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AutomatedDesign Cal-culations

PMEMBERDesignParameter

Comments

the top flange for say a columnor beam with a beta angle. Thelocal member axes can beviewed in the GUI by selecting“Beam Orientation” in theDiagrams Labels dialog (orCtrl+O keyboard shortcut).

To automate kl using AS 4100Table 5.6.3(2), the longitudinalposition of the load also needs tobe considered, i.e., as either “withinsegment” or “at segment end”.

To determine which of theseapplies, the shear forces at the endsof each design segment / sub-segment is considered. If the shearforce is found to have the samedirection and magnitude at bothends, it is assumed that loads act atthe segment end.

If on the other hand the shear forceat each end is found to havedifferent directions or magnitudes,loads are assumed to act within thesegment.

Note: The above methodincludes an allowance for theself-weight of the member to beconsidered, as the self-weightalways acts through the shearcenter.

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AutomatedDesign Cal-culations

PMEMBERDesignParameter

Comments

The net sum of the end shears isalso used to determine if the load isacting in the positive or negativelocal member y-axis direction. IfLHT is set to 1.0 for top flangeloading, the net sum is used todetermine whether the top flangeloading is acting to stabilise ordestabilise the member for lateraltorsional buckling. Negative local y-axis net loads act to destabilise thesegments / sub-segments, whereaspositive local y-axis net loads act tostabilise segments / sub-segments.

Segment andsub-segmentlayout.

PBRACE Refer to the Segment and Sub-Seg-ment Layout section above fordetails.

Nominal steelgrade.

SGR Based on section types.

kttwist

restraint fac-tor as per AS4100 Table5.6.3(1).

SKT Based on effective end restraints foreach segment / sub-segment.

klload height

factor as perAS 4100Table5.6.3(2).

SKL Based on effective end restraints foreach segment / sub-segment, andLHT design parameter (referabove).

krlateral rota-

tion restraintfactor as perAS 4100

SKR Based on effective end restraints foreach segment / sub-segment. Thisis where the distinction between “F”and “FR”, as well as “P” and “PR” isused.

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AutomatedDesign Cal-culations

PMEMBERDesignParameter

Comments

Table5.6.3(3).

Example

PARAMETER 1

CODE AUSTRALIAN

DMAX 0.4 PMEMBER ALL

DMIN 0.25 PMEMBER ALL

KX 0.75 PMEMBER ALL

KY 1.0 PMEMBER ALL

LX 4.5 PMEMBER ALL

LY 6.0 PMEMBER ALL

LHT 0.0 PMEMBER ALL

NSC 0.9 PMEMBER ALL

NSF 1.0 PMEMBER ALL

PBRACE BOTTOM0.0 F 1.0 F PMEMBER ALL

PBRACE TOP 0.0 P 0.5 L 1.0 P PMEMBER ALL

SGR 0.0 PMEMBER ALL

TRACK 2.0 PMEMBER ALL

CHECK CODE PMEMBER ALL

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Section 2

British Codes

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British Codes - Concrete Design per BS81102A.1 Design  Operations

Warning: It is strongly recommended that you perform new concrete designusing the RC Designer Module. The following is provided to allow old STAADfiles to be run.

STAAD has the capability of performing design of concrete beams, columns andslabs according to the 1997 revision of BS8110. Given the width and depth (ordiameter for circular columns) of a section, STAAD will calculate the requiredreinforcement to resist the forces and moments.

2A.2 Design Parameters

The program contains a number of parameters which are needed to perform andcontrol the design to BS8110. These parameters not only act as a method to inputrequired data for code calculations but give the Engineer control over the actualdesign process. Default values of commonly used parameters for conventionaldesign practice have been chosen as the basis. Table 2A.1 contains a complete listof available parameters with their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as BRITISH to invokedesign per BS8110.

Design Code to follow. See section5.52.2 of the Technical ReferenceManual.

BRACE 0.0 0.0 =  Column braced in bothdirections.

1.0 =  Column unbraced about local Z

Table 2A.1 - British Concrete Design BS 8110 Parameters

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ParameterName

DefaultValue

Description

direction only

2.0 =  Column unbraced about local Ydirection only

3.0 =  Column unbraced in both Y andZ directions

CLEAR 20 mm Clearance of reinforcement measuredfrom concrete surface to closest barperimeter, in current units.

DEPTH YD Depth of concrete member, in currentunits. This value default is as providedas YD in MEMBER PROPERTIES.

EFACE 0.0 Face of support location at end ofbeam, in current units.

Note: Both SFACE & EFACE mustbe positive numbers.

ELY 1.0 Member length factor about local Ydirection for column design.

ELZ 1.0 Member length factor about local Zdirection for column design.

FC 30N/mm2

Concrete Yield Stress / cube strength,in current units

FYMAIN 460N/mm2

Yield Stress for main reinforcement, incurrent units (For slabs, it is forreinforcement in both directions)

FYSEC 460N/mm2

Yield Stress for secondaryreinforcement a, in current units.Applicable to shear bars in beams

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ParameterName

DefaultValue

Description

MAXMAIN 50mm Maximum required reinforcement barsize Acceptable bars are per MINMAINabove.

MINMAIN 8mm Minimummain reinforcement bar sizeAcceptable bar sizes: 6 8 10 12 16 2025 32 40 50

MINSEC 8mm Minimum secondary bar size a.Applicable to shear reinforcement inbeams

MMAG 1.0 Factor by which column designmoments are magnified

NSECTION 10 Number of equally-spaced sections tobe considered in finding criticalmoment for beam design. The upperlimit is 20.

SERV 0.0 Serviceability checks:

0.0 =  No serviceabilitycheck performed.

1.0 =  Performserviceability check forbeams as if they werecontinuous.

2.0 =  Performserviceability check forbeams as if they weresimply supported.

3.0 =  Performserviceability check forbeams as if they werecantilever beams.

SFACE 0.0 Face of support location at start of

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ParameterName

DefaultValue

Description

beam, in current units. (Only applicablefor shear - use MEMBER OFFSET forbending )

SRA 0.0 0.0 = Orthogonal reinforcement layoutwithout considering torsional momentMxy -slabs only

-500 = Orthogonal reinforcementlayout with Mxy used to calculate Wood& Armer moments for design.

A = skew angle considered in Wood &Armer equations where A is the angle indegrees.

TRACK 0.0 0.0 =  Critical Moment will not beprinted with beam design report.Column design gives no detailedresults.

1.0 =  For beam gives min/max steel %and spacing. For columns gives adetailed table of output with additionalmoments calculated.

2.0 =  Output of TRACK 1.0List of design sag/hog moments andcorresponding required steel area ateach section of member

WIDTH ZD Width of concrete member, in currentunits. This value default is as providedas ZD in MEMBER PROPERTIES.

2A.3 Slenderness  Effects  and  Analysis  Con-siderations

STAAD provides the user with two methods of accounting for the slendernesseffects in the analysis and design of concrete members. The first method is

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equivalent to the procedure presented in BS8110 Part 1 1985 Section 3.8.2.2 Inthis section, the code recognizes that additional moments induced by deflection arepresent and states that these 'secondary' moments are accounted for by the designformula in Section 3.8.3. This is the method used in the design for concrete inSTAAD.

Alternatively STAAD houses a PDELTA ANALYSIS facility, which allows the effectsof these second order moments to be considered in the analysis rather than thedesign. In a PDELTA analysis, after solving the joint displacements of the structure,the additional moments induced in the structure are calculated. These can becompared to those calculated using the formulation of BS8110.

2A.4 Member Dimensions

Concrete members that are to be designed by STAAD must have certain sectionproperties input under the MEMBER PROPERTIES command. The followingexample demonstrates the required input:

UNIT MM

MEMBER PROPERTIES

*RECTANGULAR COLUMN 300MMWIDE X 450MMDEEP

1 3 TO 7 9 PRISM YD 450. ZD 300.

*CIRCULAR COLUMN 300MMDIAMETER

11 13 PR YD 300.

* T-SECTION - FLANGE 1000.X 200.(YD-YB)

* - STEM 250(THICK) X 350.(DEEP)

14 PRISM YD 550. ZD 1000. YB 350. ZB 250.

In the above input, the first set of members are rectangular (450mm depth x300mmwidth) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with 300mm diameter. Note that area (AX)is not provided for these members. If shear area areas ( AY & AZ ) are to beconsidered in analysis, the user may provide them along with YD and ZD. Also notethat if moments of inertias are not provided, the program will calculate them fromYD and ZD. Finally a T section can be considered by using the third definitionabove.

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2A.5 Beam Design

Beam design includes both flexure and shear. For both types of beam action, allactive beam loadings are scanned to create moment and shear envelopes andlocate the critical sections. The total number of sections considered is ten, unlessthat number is redefined with the NSECTION parameter. From the critical momentvalues, the required positive and negative bar pattern is developed with cut-offlengths calculated to include required development length.

Shear design as per BS8110 clause 3.4.5 has been followed and the procedureincludes critical shear values plus torsional moments. From these values, stirrupsizes are calculated with proper spacing. The program will scan from each end ofthe member and provide a total of two shear regions at each, depending on thechange of shear distribution along the beam. If torsion is present, the program willalso consider the provisions of BS8110 - Part 2 -section 2.4. A table of shearand/or combined torsion is then provided with critical shear.

Stirrups not bent up bars are assumed in the design. The example output belowshows a sample output of an actual reinforcement pattern developed by STAAD.The following annotations apply:

l LEVEL        -  Serial number of the bar center which may contain one or morebar groups.

l HEIGHT     -  Height of bar level from the soffit of the beam in relation to itslocal y axis.

l BAR INFO  -  Reinforcement bar information specifying number of bars andtheir size.

l FROM         -  Distance from the start of the beam to the start of the rein-forcing bar.

l TO               -  Distance from the start of the beam to the end of the rein-forcing bar.

l ANCHOR    -  States whether anchorage, either a hook or

l (STA,END)     continuation, is needed at start (STA) or at the end (END).

The following is an example TRACK 2.0 beam design output:

====================================================================

B E A M N O. 13 D E S I G N R E S U L T S - FLEXURE

LEN - 1500. mm FY - 460. FC - 30. SIZE - 300. X 300. mm

LEVEL HEIGHT BAR INFO FROM TO ANCHOR

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mm mm mm STA END-------------------------------------------------------------------

1 29. 4- 8 MM 467. 1500. NO YES2 264. 4- 8 MM 0. 1158. YES NO

REQUIRED REINF. STEEL SUMMARY :-------------------------------SECTION REINF STEEL(+VE/-VE) MOMENTS(+VE/-VE) LOAD(+VE/-

VE)( MM ) (SQ. MM ) (KN-METER)

0. 0.0/ 184.4 0.00/ 19.71 0/ 3125. 0.0/ 157.2 0.00/ 16.80 0/ 3250. 0.0/ 129.9 0.00/ 13.89 0/ 3375. 0.0/ 117.0 0.00/ 10.98 0/ 3500. 0.0/ 117.0 0.00/ 8.07 0/ 3625. 0.0/ 117.0 0.00/ 5.16 0/ 3750. 0.0/ 117.0 0.00/ 2.25 0/ 3875. 117.0/ 0.0 2.15/ 0.00 1/ 01000. 117.0/ 0.0 5.25/ 0.00 1/ 01125. 117.0/ 0.0 8.36/ 0.00 1/ 01250. 117.0/ 0.0 11.46/ 0.00 1/ 01375. 136.3/ 0.0 14.57/ 0.00 1/ 01500. 165.3/ 0.0 17.67/ 0.00 1/ 0

B E A M N O. 13 D E S I G N R E S U L T S - SHEAR

PROVIDE SHEAR LINKS AS FOLLOWS|----------------------------------------------------------------|| FROM - TO | MAX. SHEAR | LOAD | LINKS | NO. | SPACING C/C ||----------------|------------|------|-------|-----|-------------|| END 1 749 mm | 24.8 kN | 1 | 8 mm | 5 | 187 mm || 749 END 2 | 24.8 kN | 1 | 8 mm | 5 | 187 mm ||----------------------------------------------------------------|___ 7J____________________ 1500.X 300.X 300_____________________

8J____|

|||=========================================================

|| 4No8 H 264. 0.TO 1158 | | |

|| 5*8 c/c187 | | | 5*8c/c187 || 4No8 H |29. 467.TO 1500 |

||====================================================|||

||___________________________________________________________________________|_______________ _______________ _______________ _________

______| | | | | | |

|

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| 4T8 | | 4T8 | | 4T8 | ||

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||_______________| |_______________| |_______________| |_______________|

2A.6 Column Design

Columns are designed for axial force and biaxial bending at the ends. All activeloadings are tested to calculate reinforcement. The loading which producesmaximum reinforcement is called the critical load and is displayed. Therequirements of BS8110 Part 1 - section 3.8 are followed, with the user havingcontrol on the effective length in each direction by using the ELZ and ELYparameters as described in Table 2A.1. Bracing conditions are controlled by usingthe BRACE parameter. The program will then decide whether or not the column isshort or slender and whether it requires additional moment calculations. Forbiaxial bending, the recommendations of 3.8.4.5 of the code are considered.

Column design is done for square, rectangular and circular sections. Forrectangular and square sections, the reinforcement is always assumed to bearranged symmetrically. This causes slightly conservative results in certain cases.Below is a typical column design results.

Using parameter TRACK 1.0, the detailed output below is obtained. TRACK 0.0would merely give the bar configuration, required steel area and percentage,column size and critical load case.

====================================================================

C O L U M N N O. 1 D E S I G N R E S U L T S

FY - 460. FC -30. N/MM2 SQRE SIZE - 300. X 300. MM,

AREA OF STEEL REQUIRED = 940. SQ. MM.

BAR CONFIGURATION REINF PCT. LOAD LOCATION----------------------------------------------------

12 10 MM 1.047 1 EACH END(PROVIDE EQUAL NUMBER OF BARS AT EACH FACE)

----------------------------------------------------|BRACED /SLENDER in z E.L.z= 4500 mm (3.8.1.3 & 5)|

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|BRACED /SLENDER in y E.L.y= 4500 mm (3.8.1.3 & 5)||END MOMS. MZ1= -12 MZ2= -24 MY1= -15 MY2= -31||SLENDERNESS MOMTS. KNM: MOMZ= 2 MOMY= 2 ||DESIGN LOADS KN METER: MOM.= 55 AXIAL LOAD= 74||DESIGNED CAP. KN METER: MOM.= 55 AXIAL CAP.= 74|----------------------------------------------------

2A.7 Slab  Design

Slabs are designed to BS8110 specifications. To design a slab, it must first bemodeled using finite elements. The command specifications are in accordance withSection 5.52 of the Technical Reference Manual.

A typical example of element design output is shown in below. The reinforcementrequired to resist the Mx moment is denoted as longitudinal reinforcement and thereinforcement required to resist the My moment is denoted as transversereinforcement ( Fig. 4.1 ). The following parameters are those applicable to slabdesign:

l FYMAIN - Yield stress for all reinforcing steel

l FC - Concrete grade

l CLEAR - Distance from the outer surface to the edge of the bar. This is con-sidered the same on both surfaces.

l SRA - Parameter which denotes the angle of the required transverse rein-forcement relative to the longitudinal reinforcement for the calculation ofWood & Armer design moments.

Other parameters, as shown in Table 2A.1 are not applicable.

Wood & Armer equations

Ref: R H WOOD CONCRETE 1968 (FEBRUARY)

If the default value of zero is used for the parameter SRA, the design will be basedon the Mx and My moments which are the direct results of STAAD analysis. The SRAparameter (Set Reinforcement Angle) can be manipulated to introduce Wood &Armer moments into the design replacing the pure Mx, My moments. These newdesign moments allow the Mxy moment to be considered when designing thesection. Orthogonal or skew reinforcement may be considered. SRA set to -500 willassume an orthogonal layout. If however a skew is to be considered, an angle isgiven in degrees measured anticlockwise (positive) from the element local x-axis to

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the reinforcement bar. The resulting Mx* and My* moments are calculated andshown in the design format.

The design of the slab considers a fixed bar size of 16 mm in both directions withthe longitudinal bar being the layer closest to the slab exterior face. Typical outputis as follows:

ELEMENT DESIGN SUMMARY-BASED ON 16mm BARS-----------------------------------------MINIMUM AREAS ARE ACTUAL CODE MIN % REQUIREMENTS.PRACTICAL LAYOUTS ARE AS FOLLOWS:FY=460, 6No.16mm BARS AT 150mm C/C = 1206mm2/metreFY=250, 4No.16mm BARS AT 250mm C/C = 804mm2/metre

ELEMENT LONG. REINF MOM-X /LOAD TRANS. REINF MOM-Y/LOAD

(mm2/m) (kN-m/m) (mm2/m) (kN-m/m)

--------------------------------------------------------------------------| WOOD & ARMER RESOLVED MOMENTS FOR ELEMENT: 47 UNITS: METREkN || LOAD MX MY MXY MX* MY*/Ma* ANGLE

|| 1 -10.441 -13.347 1.270 0.000 0.000 0.000TOP || 1 -10.441 -13.347 1.270 -11.710 -14.617 0.000BOTT || 3 -9.541 -11.995 0.986 0.000 0.000 0.000TOP || 3 -9.541 -11.995 0.986 -10.527 -12.981 0.000BOTT |--------------------------------------------------------------------

------

47 TOP : 195. 0.00 / 0 195. 0.00/ 0

BOTT: 229. -11.71 / 1 329. -14.62/ 1

2A.8 Shear Wall Design

Design of shear walls in accordance with BS 8110 has been added to the featuresof the program.

The program implements the provisions of BS 8110 for the design of shear walls.It performs in-plane shear, compression, as well as in-plane and out-of-planebending design of reinforcing. The shear wall is modeled by a single or acombination of Surface elements. The use of the Surface element enables thedesigner to treat the entire wall as one entity. It greatly simplifies the modeling ofthe wall and adds clarity to the analysis and design output. The results are

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presented in the context of the entire wall rather than individual finite elementsthereby allowing users to quickly locate required information.

The program reports shear wall design results for each load case/combination foruser specified number of sections given by SURFACE DIVISION (default value is10) command. The shear wall is designed at these horizontal sections. The outputincludes the required horizontal and vertical distributed reinforcing, theconcentrated (in-plane bending) reinforcing and the link required due to out-of-plane shear.

General Format

START SHEARWALL DESIGN

CODE BRITISH

FYMAIN f1

FC f2

HMIN f3

HMAX f4

VMIN f5

VMAX f6

EMIN f7

EMAX f8

LMIN f9

LMAX f10

CLEAR f11

TWOLAYERED f12

KSLENDER f13

DESIGN SHEARWALL LIST shearwall-list

END

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The next table explains parameters used in the shear wall designcommand block above.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

FYMAIN 460 Mpa Yield strength of steel, in currentunits.

FC 30 Mpa Compressive strength ofconcrete, in current units.

HMIN 6 Minimum size of horizontalreinforcing bars (range 6 mm –36 mm). If input is 6 (integernumber) the program willassume 6 mm diameter bar.

HMAX 36 Maximum size of horizontalreinforcing bars (range 6 mm –36 mm). If input is 6 (integernumber) the program willassume 6 mm diameter bar.

VMIN 6 Minimum size of verticalreinforcing bars (range 6mm –36mm). If input is 6 (integernumber) the program willassume 6 mm diameter bar.

VMAX 36 Maximum size of verticalreinforcing bars (range 6mm –36mm). If input is 6 (integernumber) the program willassume 6 mm diameter bar.

EMIN 6 Minimum size of verticalreinforcing bars located in edge

Table 2A.2 - Shear Wall Design Parameters

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ParameterName

DefaultValue

Description

zones (range 6mm – 36mm). Ifinput is 6 (integer number) theprogram will assume 6 mmdiameter bar.

EMAX 36 Maximum size of verticalreinforcing bars located in edgezones (range 6mm – 36mm). Ifinput is 6 (integer number) theprogram will assume 6 mmdiameter bar.

LMIN 6 Minimum size of links (range6mm – 16mm). If input is 6(integer number) the programwill assume 6 mm diameter bar.

LMAX 16 Maximum size of links (range6mm – 16mm). If input is 6(integer number) the programwill assume 6 mm diameter bar.

CLEAR 25 mm Clear concrete cover, in currentunits.

TWOLAYERED 0 Reinforcement placement mode:

0. single layer, each direction

1. two layers, each direction

KSLENDER 1.5 Slenderness factor for findingeffective height.

The following example starts from the definition of shear wall and ends at the shearwall design.

Example

.

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.

SET DIVISION 12

SURFACE INCIDENCES

2 5 37 34 SUR 1

19 16 65 68 SUR 2

11 15 186 165 SUR 3

10 6 138 159 SUR 4

.

.

.

SURFACE PROPERTY

1 TO 4 THI 18

SUPPORTS

1 7 14 20 PINNED

2 TO 5 GEN PIN

6 TO 10 GEN PIN

11 TO 15 GEN PIN

19 TO 16 GEN PIN

.

.

SURFACE CONSTANTS

E 3150

POISSON 0.17

DENSITY 8.68E-005

ALPHA 5.5E-006

.

.

START SHEARWALL DES

CODE BRITISH

UNIT NEWMMS

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FC 25

FYMAIN 460

TWO1

VMIN 12

HMIN 12

EMIN 12

DESIGN SHEA LIST 1 TO 4

END

Notes

1. Command SET DIVISION 12 indicates that the surface boundary node-to-node segments will be subdivided into 12 fragments prior to finite elementmesh generation.

2. Four surfaces are defined by the SURFACE INCIDENCES command.

3. The SUPPORTS command includes the new support generation routine. Forinstance, the line 2 TO 5GEN PIN assigns pinned supports to all nodesbetween nodes 2 and 5. As the node-to-node distances were previouslysubdivided by the SET DIVISION 12 command, there will be an additional11 nodes between nodes 2 and 5. As a result, all 13 nodes will be assignedpinned supports. Please note that the additional 11 nodes are not individuallyaccessible to the user. They are created by the program to enable the finiteelement mesh generation and to allow application of boundary constraints.

4. Surface thickness and material constants are specified by the SURFACEPROPERTY and SURFACE CONSTANTS, respectively.

5. The shear wall design commands are listed between lines STARTSHEARWALL DES and END. The CODE command selects the design codethat will be the basis for the design. For British code the parameter isBRTISH. TheDESIGN SHEARWALL LIST command is followed by a listof previously defined Surface elements intended as shear walls and/or shearwall components.

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Technical Overview

The program implements provisions of section 3.9 of BS 8110:Part 1:1997 andrelevant provisions as referenced therein, for all active load cases. The wall isdesigned as unbraced reinforced wall. The following steps are performed for eachof the horizontal sections of the wall set using the SURFACE DIVISION command(see Description above).

Checking of slenderness limit

The slenderness checking is done for out-of-plane direction. For out-of-planedirection, the wall is assumed to be simply supported. Hence, the provisions ofclause 3.9.3.2.2 and 3.9.4.2 are applicable. The default effective height is 1.5times the clear height. User can change the effective height. The limit forslenderness is as per table 3.23 for unbraced wall, which is taken as 30.

Design for in-plane bending (denoted by Mz in the shear wall force output)

Walls are assumed to be cantilever beams fixed at their base and carrying loads tothe foundation.

Extreme compression fibre to centroid of tension (concentrated) reinforcementdistance, d, is taken as 0.8 horizontal length of the wall. Flexural design of the wallis carried out in accordance with the provisions of clause no. 3.4.4. The flexural(concentrated vertical ) reinforcing is located at both ends (edges) of the length ofthe wall. The edge reinforcement is assumed to be distributed over a length of 0.2times horizontal length on each side. This length is inclusive of the thickness of thewall. Minimum reinforcements are according to table 3.25.

Design for in-plane shear (denoted by Fxy in the shear wall force output)

Limit on the nominal shear strength, v is calculated as per clause no. 3.4.5.2.

Nominal shear strength of concrete is computed as per table 3.8.

The design shear stress is computed as per clause no. 3.4.5.12 taking intoconsideration the effect of axial load.  The area of reinforcement is calculated andchecked against the minimum area as per clause no. 3.12.7.4.

Design for compression and out-of-plane vertical bending (denoted by Fy and Myrespectively in the shear wall force output)

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The wall panel is designed as simply supported (at top and bottom), axially loadedwith out-of-plane uniform lateral load, with maximummoments and deflectionsoccurring at mid-height. Design is done as per clause no. 3.8.4 for axially loadedcolumn with uni-axial bending. The minimum reinforcement percentage is as pertable 3.25. The maximum reinforcement percentage of vertical reinforcement is asper clause no. 3.12.6.3. Links if necessary are calculated as per the provisions ofclause 3.12.7.5.

Design for out-of-plane shear (denoted by Qy in the shear wall force output)

The out-of-plane shear arises from out-of-plane loading. The design shear stress iscalculated as per 3.4.5.2 and shear strength of concrete section is calculated as pertable 3.8 considering vertical reinforcement as tension reinforcement.

Shear reinforcements in the form of links are computed as per table 3.7 and theprovisions of clause 3.12.7.5.

Design for out-of-plane horizontal bending (denoted by Mx in the shear wall forceoutput)

The horizontal reinforcement already calculated from in-plane shear is checkedagainst the whole section subjected to out-of-plane bending and axial load. Theaxial load in this case is the in-plane shear. The section is again designed as axiallyloaded column under uni-axial bending as per the provisions of clause 3.8.4. Extrareinforcement in the form of horizontal bars, if necessary, is reported.

Shear Wall Design With Opening

The Surface element has been enhanced to allow design of shear walls withrectangular openings. The automatic meshing algorithm has been improved toallow variable divisions along wall and opening(s) edges. Design and output areavailable for user selected locations.

Description

Shear walls modeled in STAAD.Pro may include an unlimited number of openings.Due to the presence of openings, the wall may comprise up with different wallpanels.

1. Shear wall set-up

Definition of a shear wall starts with a specification of the surface elementperimeter nodes, meshing divisions along node-to-node segments,

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opening(s) corner coordinates, and meshing divisions of four edges of theopening(s).

SURFACE INCIDENCE n1, ..., ni SURFACE s DIVISION sd1,..., sdj -

RECOPENING x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4 DIVISIONod1, ..., odk

Where:

n1, ..., ni      -   node numbers on the perimeter of the shear wall,

s           -  surface ordinal number,

sd1, ..., sdj   -   number of divisions for each of the node-to-nodedistance on the surface perimeter,

x1 y1 z1 (...) -  coordinates of the corners of the  opening,

od1, ..., odk  -  divisions along edges of the opening.

Note: If the sd1, ..., sdj or the od1, ..., odk list does notinclude all node-to-node segments, or if any of the numberslisted equals zero, then the corresponding division number isset to the default value (=10, or as previously input by theSET DIVISION command).

Default locations for stress/force output, design, and design output are setas follows:

SURFACE DIVISION X xd

SURFACE DIVISION Y yd

where:

xd                  - number of divisions along X axis,

yd                  - number of divisions along Y axis.

Note: xd and yd represent default numbers of divisions for each edge ofthe surface where output is requested. The output is provided forsections located between division segments. For example, if the number

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of divisions = 2, then the output will be produced for only one section (atthe center of the edge).

2. Stress/force output printing

Values of internal forces may be printed out for any user-defined section ofthe wall. The general format of the command is as follows:

PRINT SURFACE FORCE (ALONG ξ) (AT a) (BETWEEN d1, d2)LIST s1, ...,si

where:

ξ        -   local axis of the surface element (X or Y),

a           -   distance along the ξ axis from start of the member to thefull cross-section of the wall,

d1, d2   -   coordinates in the direction orthogonal to ξ, delineating afragment of the full cross-section for which the output is desired.**

s1, ...,si -   list of surfaces for output generation

** The range currently is taken in terms of local axis. If the local axis isdirected away from the surface, the negative range is to be entered.

Note: If command ALONG is omitted, direction Y (default) isassumed. If command AT is omitted, output is provided for allsections along the specified (or default) edge. Number of sectionswill be determined from the SURFACE DIVISION X or SURFACEDIVISION Y input values. If the BETWEEN command is omitted,the output is generated based on full cross-section width.

3. Definition of wall panels

Input syntax for panel definition is as follows:

START PANEL DEFINITION

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SURFACE i PANEL j ptype x1 y1 z1 x2 y2 z2 x3 y3z3 x4 y4 z4

ENDPANEL DEFINITION

where:

i                     -  ordinal surface number,

j                     -  ordinal panel number,

ptype              - WALL

x1 y1 z1 (...)  -  coordinates of the corners of the panel

Note: Design of COLUMN and BEAM panels is currently not available.

4. Shear wall design

The program implements different provisions of design of walls as per codeBS 8110. General syntax of the design command is as follows:

START SHEARWALL DESIGN

(...)

DESIGN SHEARWALL (AT c) LIST s

TRACK tr

ENDSHEARWALL DESIGN

Parameter TRACK specifies how detailed the design output should be:

0   - indicates a basic set of results data (default),

1   - full design output will be generated.

If the command AT is omitted, the design proceeds for all cross sections of thewall or panels, as applicable, defined by the SURFACE DIVISION X orSURFACE DIVISION Y input values.

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a. No panel definition.

Design is performed for the specified horizontal full cross-section, located at adistance c from the origin of the local coordinates system. If opening is foundthen reinforcement is provided along sides of openings. The area ofhorizontal and vertical bars provided along edges of openings is equal to thatof the respective interrupted bars.

b. Panels have been defined.

Design is performed for all panels, for the cross-section located at a distance cfrom the start of the panel.

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British Codes - Steel Design per BS5950:20002B.1 General

The design philosophy embodied in BS5950:2000 is built around the concept oflimit state design, used today in most modern steel design codes. Structures aredesigned and proportioned taking into consideration the limit states at which theybecome unfit for their intended use. Two major categories of limit state arerecognized - serviceability and ultimate. The primary considerations in ultimatelimit state design are strength and stability while that in serviceability limit state isdeflection. Appropriate safety factors are used so that the chances of limits beingsurpassed are acceptably remote.

In the STAAD implementation of BS5950:2000, members are proportioned to resistthe design loads without exceeding the limit states of strength and stability.Accordingly, the most economic section is selected on the basis of the least weightcriteria. This procedure is controlled by the designer in specification of allowablemember depths, desired section type or other such parameters. The code checkingportion of the program checks that code requirements for each selected section aremet and identifies the governing criteria.

The complete B.S.C. steel tables for both hot rolled and hollow sections are builtinto the program for use in specifying member properties as well as for the actualdesign process. See section 2B.4 for information regarding the referencing of thesesections. In addition to universal beams, columns, joists, piles, channels, tees,composite sections, beams with cover plates, pipes, tubes, and angles, there is aprovision for user provided tables.

STAAD.Pro 2006 and later have the additional option to design tapered I shaped(wide flange) beams according to Annex G of BS5950.  See Section 2B.13 for acomplete description.

Single  Angle  SectionsAngle sections are un-symmetrical and when using BS 5950:2000 table 25 youmust consider four axes: two principal, u-u and v-v and two geometric, a-a and b-b. The effective length for the v-v axis, Lvv, is taken as the LVV parameter or LY *KY, if not specified.  The a-a and b-b axes are determined by which leg of the angleis fixed by the connection and should be specified using the LEG parameter, see

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section 5B.6 for more information on the LEG parameter.  The effective length inthe a-a axis is taken as LY * KY and the effective length in the b-b axis as LZ * KZ.

The following diagram shows the axes for angles which have been defined witheither an ST or RA specification and is connected by its longer leg (i.e., a-a axis isparallel to the longer leg).

Figure 2.1 - Single angle sections A) ST angle & USER table angles and B) RA angle

2B.2 Analysis  Methodology

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loadingspecifications and using appropriate load factors to create necessary loadingsituations. Depending upon the analysis requirements, regular stiffness analysis orP-Delta analysis may be specified. Dynamic analysis may also be performed andthe results combined with static analysis results.

2B.3 Member Property Specifications

For specification of member properties, the steel section library available in STAADmay be used. The next section describes the syntax of commands used to assignproperties from the built-in steel table. Member properties may also be specifiedusing the User Table facility. Any user-defined section may be specified, except for

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GENERAL or PRISMATIC sections. For more information on these facilities, refer toSection 1.7 the STAAD Technical Reference Manual.

2B.4 Built-In Steel Section Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, the properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredduring the analysis of these members.

Almost all BSI steel sections are available for input. A complete listing of thesections available in the built-in steel section library may be obtained by using thetools of the graphical user interface.

Refer to Section 1.7.2 of the Technical Reference Manual for additional information.

Following are the descriptions of different types of sections available:

Universal Beams, Columns, and Piles

All rolled universal beams, columns and pile sections are available. The followingexamples illustrate the designation scheme.

20 TO 30 TA ST UB305X165X54

33 36 TA ST UC356X406X287

100 102 106 TA ST UP305X305X186

Rolled Steel Joists

Joist sections may be specified as they are listed in BSI-80 with the weight omitted.In those cases where two joists have the same specifications but different weights,the lighter section should be specified with an "A" at the end.

10 TO 20 TA ST JO152X127

1 2 TA ST JO127X114A

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Channels

All rolled steel channel sections from the BSI table have been incorporated inSTAAD. The designation is similar to that of the joists. The same designationscheme as in BSI tables may be used with the weight omitted.

10 TO 15 TA ST CH305X10255 57 59 61 TA ST CH178X76

Double Channels

Back-to-back double channels, with or without spacing between them, areavailable. The letter "D" in front of the section name will specify a double channel(e.g., D CH102X51, D CH203X89, etc.)

51 52 53 TA D CH152X8970 TO 80 TA D CH305X102 SP 5.

(specifies a double channel with a spacing of 5 length units)

Note: Face-to-face double channels can not be used in a CHECK CODEcommand.

Tee Sections

Tee sections are not input by their actual designations, but instead by referring tothe universal beam shapes from which they are cut. For example,

54 55 56 TA T UB254X102X22

(tee cut from UB254X102X22)

Angles

All equal and unequal angles are available for analysis. Two types of specificationsmay be used to describe an angle section, either a standard, ST specification orreversed angle, RA specification. Note, however, that only angles specified with anRA specification can be designed.

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The standard angle section is specified as follows:

15 20 25 TA ST UA200X150X18

This specification may be used when the local STAAD z-axis corresponds to the V-Vaxis specified in the steel tables. If the local STAAD y-axis corresponds to the V-Vaxis in the tables, type specification "RA" (reverse angle) may be used.

35 TO 45 TA RA UA200X150X18

Double Angles

Short leg back-to-back or long leg back-to-back double angles can be specified byinputting the word SD or LD, respectively, in front of the angle size. In case of anequal angle, either LD or SD will serve the purpose. For example,

14 TO 20 TA LD UA200X200X16 SP 1.523 27 TA SD UA80X60X6

"SP" denotes spacing between the individual angle sections.

Note: If the section is defined from a Double Angle User Table, then the sectionproperties must be defined with an 11th value which defines the radius ofgyration about an individual sections’ principal v-v axis (See TechnicalReference Manual, 5.19 User Steel Table Specification)

Pipes (Circular Hollow Sections)

To designate circular hollow sections from BSI tables, use PIP followed by thenumerical value of diameter and thickness of the section in mm omitting thedecimal section of the value provided for diameter. The following example willillustrate the designation.

10 15 TA ST PIP213.2

(specifies a 21.3 mm dia. pipe with 3.2 mm wall thickness)

Circular hollow sections may also be provided by specifying the outside and insidediameters of the section. For example,

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1 TO 9 TA ST PIPE OD 25.0 ID 20.0

(specifies a pipe with outside dia. of 25 and inside dia. of 20 in current lengthunits)

Only code checking and no member selection will be performed if this type ofspecification is used.

Rectangular or Square Hollow Sections (Tubes)

Designation of tubes from the BSI steel table is illustrated below:

Figure 2.2 - BSI tube nomenclature

Example:

15 TO 25 TA ST TUB160808.0

Tubes, like pipes, can also be input by their dimensions (Height, Width andThickness) and not by any table designations.

6 TA ST TUBEDT 8.0WT 6.0 TH 0.5

(A TUBE THAT HAS A HEIGHT OF 8, A WIDTH OF 6, AND AWALLTHICKNESS OF 0.5 LENGTH UNITS)

Note: Only code checking and no member selection is performed for TUBEsections specified this way.

2B.5 Member  Capacities

The basic measure of capacity of a beam is taken as the plastic moment of thesection. This is a significant departure from the standard practice followed in

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BS449, in which the limiting condition was attainment of yield stress at the extremefibres of a given section. With the introduction of the plastic moment as the basicmeasure of capacity, careful consideration must be given to the influence of localbuckling on moment capacity. To assist this, sections are classified as either Class1, plastic, Class 2, compact, Class 3, semi-compact or Class 4, slender, whichgoverns the decision whether to use the plastic or the elastic moment capacity. Thesection classification is a function of the geometric properties of the section. STAADis capable of determining the section classification for both hot rolled and built upsections. In addition, for slender sections, BS5950 recommends the use of a 'stressreduction factor' to reduce the design strength. This factor is again a function of thegeometry of the section and is automatically determined by STAAD for use in thedesign process.

Axial  Tension

In members with axial tension, the tensile load must not exceed the tensioncapacity of the member. The tension capacity of the member is calculated on thebasis of the effective area as outlined in Section 4.6 of the code. STAAD calculatesthe tension capacity of a given member per this procedure, based on a usersupplied net section factor (NSF-a default value of 1.0 is present but may be alteredby changing the input value - see Table 2B.1), proceeding with member selectionor code check accordingly. BS5950 does not have any slenderness limitations fortension members.

Compression

Compression members must be designed so that the compression resistance of themember is greater than the axial compressive load. Compression resistance isdetermined according to the compressive strength, which is a function of theslenderness of the gross section, the appropriate design strength and the relevantstrut characteristics. Strut characteristics take into account the considerableinfluence residual rolling and welding stresses have on column behavior. Based ondata collected from extensive research, it has been determined that sections such astubes with low residual stresses and Universal Beams and Columns are ofintermediate performance. It has been found that I-shaped sections are lesssensitive to imperfections when constrained to fail about an axis parallel to theflanges. These research observations are incorporated in BS5950 through the useof four strut curves together with a selection of tables to indicate which curve to usefor a particular case. Compression strength for a particular section is calculated in

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STAAD according to the procedure outlined in Annex C of BS5950 wherecompression strength is seen to be a function of the appropriate Robertsonconstant ( representing Strut Curve) corresponding Perry factor, limitingslenderness of the member and appropriate design strength.

A departure from BS5950:1990, generally compression members are no longerrequired to be checked for slenderness limitations, however, this option can beincluded by specifying a MAIN parameter.  Note, a slenderness limit of 50 is stillapplied on double angles checked as battened struts as per clause 4.7.9.

Axially  Loaded  Members  With  Moments

In the case of axially loaded members with moments, the moment capacity of themember must be calculated about both principal axes and all axial forces must betaken into account. If the section is plastic or compact, plastic moment capacitieswill constitute the basic moment capacities subject to an elastic limitation. Thepurpose of this elastic limitation is to prevent plasticity at working load. For semi-compact or slender sections, the elastic moment is used. For plastic or compactsections with high shear loads, the plastic modulus has to be reduced toaccommodate the shear loads. The STAAD implementation of BS5950 incorporatesthe procedure outlined in section 4.2.5 and 4.2.6 to calculate the appropriatemoment capacities of the section.

For members with axial tension and moment, the interaction formula as outlined insection 4.8.2 is applied based on effective tension capacity.

For members with axial compression and moment, two principal interactionformulae must be satisfied – Cross Section Capacity check (4.8.3.2) and theMember Buckling Resistance check (4.8.3.3 ). Three types of approach for themember buckling resistance check have been outlined in BS5950:2000 - thesimplified approach (4.8.3.3.1), the more exact approach (4.8.3.3.2) and AnnexI1 for stocky members. As noted in the code, in cases where neither the major axisnor the minor axis moment approaches zero, the more exact approach may bemore conservative than the simplified approach. It has been found, however, thatthis is not always the case and STAAD therefore performs both checks, comparingthe results in order that the more appropriate criteria can be used.

Additionally the equivalent moment factors, mxmyand m

yx, can be specified by

the user or calculated by the program.

Members subject to biaxial moments in the absence of both tensile andcompressive axial forces are checked using the appropriate method described

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above with all axial forces set to zero. STAAD also carries out cross checks forcompression only, which for compact/plastic sections may be more critical. If this isthe case, COMPRESSION will be the critical condition reported despite the presenceof moments.

Shear

A member subjected to shear is considered adequate if the shear capacity of thesection is greater than the shear load on the member. Shear capacity is calculated inSTAAD using the procedure outlined in section 4.2.3, also 4.4.5 and Annex H3 ifappropriate, considering the appropriate shear area for the section specified.

Lateral Torsional Buckling

Since plastic moment capacity is the basic moment capacity used in BS5950,members are likely to experience relatively large deflections. This effect, coupledwith lateral torsional buckling, may result in severe serviceability limit state. Hence,lateral torsional buckling must be considered carefully.

The procedure to check for lateral torsional buckling as outlined in section 4.3 hasbeen incorporated in the STAAD implementation of BS5950. According to thisprocedure, for a member subjected to moments about the major axis, the'equivalent uniform moment' on the section must be less than the lateral torsionalbuckling resistance moment. For calculation of the buckling resistance moment, theprocedure outlined in Annex B.2 has been implemented for all sections with theexception of angles. In Annex B.2., the resistance moment is given as a function ofthe elastic critical moment, Perry coefficient, and limiting equivalent slenderness,which are calculated within the program; and the equivalent moment factor, m

LT,

which is determined as a function of the loading configuration and the nature of theload (stabilizing, destabilizing, etc).

RHS  Sections - Additional  Provisions

Rectangular Hollow sections are treated in accordance with S.C.I.recommendations in cases when the plastic axis is in the flange. In such cases, thefollowing expressions are used to calculate the reduced plastic moduli:

For n ≥ 2t(D-2t)/A

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For n ≥ 2t(B-2t)/A

2B.6 Design Parameters

Available design parameters to be used in conjunction with BS5950 are listed intable 2B.1 along with their default values.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

Default Value Description

CODE -

Must be specified as BS5950

Design Code to follow.

See section 5.48.1 of theTechnical Reference Manual.

AD Depth at end/2Distance between thereference axis and the axis ofrestraint. See G.2.3

BEAM 3.0

Beam divisions

0. Design only for endmoments or those loca-tions specified by theSECTION command.

1. Calculate forces andmoments at 12th pointsalong the member.Establish the locationwhere Mz is the max-imum. Use the forcesand moments at thatlocation. Clause checksat one location.

Table 2B.1 - British Steel Design BS5950:2000 Parameters

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ParameterName

Default Value Description

2. Same as BEAM = 1.0but additional checksare carried out for eachend.

3. Calculate moments at12th points along themember.  Clause checksat each location includ-ing the ends of themember.

CAN 0

Deflection check method. SeeNote 1 below.

0. Deflection check basedon the principle thatmaximum deflectionoccurs within the spanbetween DJ1 and DJ2.

1. Deflection check basedon the principle thatmaximum deflection isof the cantilever type(see note below)

CB 1.0

Moment calculation:

1. BS5950 per clause B.2.5(continuous) to calculateMb.

2. To calculate Mbs (sim-ple) as per Clause 4.7.7as opposed to Mb.

DFF

None(Mandatory fordeflection check,TRACK 4.0)

"Deflection Length" / Maxm.allowable local deflection

See Note 1d below.

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ParameterName

Default Value Description

DJ1Start Jointof member

Joint No. denoting startingpoint for calculation of"Deflection Length" . See Note1 below.

DJ2End Joint ofmember

Joint No. denoting end pointfor calculation of "DeflectionLength". See Note 1 below.

DMAX * 100.0cm Maximum allowable depth

DMIN * 0.0 cm Minimum allowable depth

ESTIFF 0.0

Clauses 4.8.3.3.1 and4.8.3.3.2

0.0 =  Fail ratiouses MIN of4.8.3.3.1,4.8.3.3.2. andAnnex I1 checks.

1.0  =  Fail ratiouses MAX of4.8.3.3.1,4.8.3.3.2. andAnnex I1 checks.

KY 1.0K factor value in local y - axis.Usually, this is the minor axis.

KZ 1.0K factor value in local z - axis.Usually, this is the major axis.

LEG 0.0

Valid range from 0 – 7 and10. The values correspond totable 25 of BS5950 forfastener conditions. See note2 below.

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ParameterName

Default Value Description

LVV *

Maximum of Lyy

and Lzz(Lyy is a term

usedby BS5950)

Used in conjunction with LEGfor Lvv as per BS5950 table25 for double angles. Seenote 6 below.

LY * Member Length

Length in local y - axis(current units) to calculate(KY)(LY)/Ryy slendernessratio.

LZ * Member Length

Length in local z - axis(current units) to calculate(KZ)(LZ)/Rzz slendernessratio.

MLT 1.0Equivalent moment factor forlateral torsional buckling asdefined in clause 4.8.3.3.4

MX 1.0Equivalent moment factor formajor axis flexural buckling asdefined in clause 4.8.3.3.4

MY 1.0Equivalent moment factor forminor axis flexural buckling asdefined in clause 4.8.3.3.4

MYX 1.0

Equivalent moment factor forminor axis lateral flexuralbuckling as defined in clause4.8.3.3.4

NSF 1.0Net section factor for tensionmembers.

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ParameterName

Default Value Description

PNL * 0.0

Transverse stiffener spacing(‘a’ in Annex H1)

0.0  =  Infinity

Any other value used in thecalculations.

PY *Set according tosteel grade (SGR)

Design strength of steel

MAIN 0.0

Slenderness limit for memberswith compression forces,effective length/ radius ofgyration, for a given axis:

0.0 =  Slendernessnot performed.

1.0 =  Mainstructural member(180)

2.0 =  Secondarymember. (250)

3.0 =  Bracing etc(350)

RATIO 1.0Permissible ratio of the actualcapacities.

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ParameterName

Default Value Description

SAME** 0.0

Controls the sections to tryduring a SELECT process.

0.0  =  Try everysection of thesame type asoriginal

1.0  =  Try onlythose sectionswith a similarname as original,e.g., if the originalis an HEA 100,then only HEAsections will beselected, even ifthere are HEM’s inthe same table.

SBLT 0.0

Identify Section type forsection classification

0.0 =  RolledSection

1.0 =  Built upSection

2.0 =  Coldformed section

SWAY none

Specifies a load case numberto provide the sway loadingforces in clause 4.8.3.3.4 (Seeadditional notes)

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ParameterName

Default Value Description

SGR 0.0

Steel Grade per BS4360

0.0 =  Grade S275

1.0 =  Grade S355

2.0 =  Grade S460

3.0 =   As per GB1591 – 16 Mn

TB 0.00.0 =  Elastic stress analysis

1.0 =  Plastic stress analysis

TRACK 0.0

Output details

0.0 =  Suppress allmember capacityinfo.

1.0 =  Print allmembercapacities.

2.0 =  Printdetailed designsheet.

4.0 =  DeflectionCheck (separatecheck to mainselect / checkcode)

UNF 1.0

Factor applied to unsupportedlength for Lateral TorsionalBuckling effective length persection 4.3.6.7 of BS5950.

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ParameterName

Default Value Description

UNL * Member Length

Unsupported Length forcalculating Lateral TorsionalBuckling resistance momentsection 4.3.6.7 of BS5950.

WELD1.0 closed

2.0 open

Weld Type, see AISC steeldesign

1.0  =  Closedsections.  Weldingon one side only(except for websof wide flange andtee sections)

2.0  =  Opensections.  Weldingon both sides(except pipes andtubes)

* current units must be considered.

**For angles, if the original section is an equal angle, then the selected section willbe an equal angle and vice versa for unequal angles.

Note: There was an NT parameter in STAAD.Pro 2005 build 1003 which is nowautomatically calculated during the design as it is load case dependant.

Notes

1. CAN, DJ1, and DJ2 – Deflection

a. When performing the deflection check, you can choose between twomethods. The first method, defined by a value 0 for the CAN parameter,is based on the local displacement. Local displacement is described inSection 5.44 of the Technical Reference Manual.

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If the CAN parameter is set to 1, the check will be based on cantileverstyle deflection. Let (DX1, DY1, DZ1) represent the nodaldisplacements (in global axes) at the node defined by DJ1 (or in theabsence of DJ1, the start node of the member). Similarly, (DX2, DY2,DZ2) represent the deflection values at DJ2 or the end node of themember.

Compute Delta = SQRT((DX2 - DX1)2 + (DY2 - DY1)2 + (DZ2 - DZ1)2)

Compute Length = distance between DJ1 & DJ2 or, between startnode and end node, as the case may be.

Then, if CAN is specified a value 1, dff = L/Delta

Ratio due to deflection = DFF/dff

b. If CAN = 0, deflection length is defined as the length that is used forcalculation of local deflections within a member. It may be noted thatfor most cases the “Deflection Length” will be equal to the length of themember. However, in some situations, the “Deflection Length” may bedifferent. A straight line joining DJ1 and DJ2 is used as the referenceline from which local deflections are measured.

For example, refer to the figure below where a beam has beenmodeled using four joints and three members. The “Deflection Length”for all three members will be equal to the total length of the beam inthis case. The parameters DJ1 and DJ2 should be used to model thissituation. Thus, for all three members here, DJ1 should be 1 and DJ2should be 4.

D = Maximum local deflection for members 1, 2, and 3.

PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

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c. If DJ1 and DJ2 are not used, "Deflection Length" will default to themember length and local deflections will be measured from originalmember line.

d. It is important to note that unless a DFF value is specified, STAAD willnot perform a deflection check. This is in accordance with the fact thatthere is no default value for DFF.

e. The above parameters may be used in conjunction with other availableparameters for steel design.

2. LEG – follows the requirements of BS5950 table 28. This table concerns thefastener restraint conditions for angles, double angles, tee sections andchannels for slenderness. The following values are available:

ClauseBold Con-figuration

LegLEG Param-

eter

4.7.10.2

Single Angle

(a) - 2 boltsshort leg 1.0

long leg 3.0

(b) - 1 boltsshort leg 0.0

long leg 2.0

4.7.10.3 DoubleAngles

(a) - 2 boltsshort leg 3.0

long leg 7.0

(b) - 1 boltsshort leg 2.0

long leg 6.0

(c) - 2 boltslong leg 1.0

short leg 5.0

(d) - 1 boltslong leg 0.0

short leg 4.0

Table 2B.2 - LEG Parameter values

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ClauseBold Con-figuration

LegLEG Param-

eter

4.7.10.4 Chan-nels

(a) - 2 or more rows ofbolts

1.0

(b) - 1 row of bolts 0.0

4.7.10.5 Tee Sec-tions

(a) - 2 or more rows ofbolts

1.0

(b) - 1 row of bolts 0.0

The slenderness of single and double angle, channel and tee sections arespecified in BS 5950 table 25 depending on the connection provided at theend of the member.  To define the appropriate connection, a LEG parametershould be assigned to the member.

The following list indicates the value of the LEG parameter required to matchthe BS5950 connection definition:

Clause 4.7.10.2 Single Angle:

a. 2 Bolts: Short leg = 1.0, Long Leg = 3.0

b. 1 Bolt: Short Leg = 0.0, Long Leg = 2.0

For single angles, the slenderness is calculated for the geometric axes, a-aand b-b as well as the weak v-v axis.  The effective lengths of the geometricaxes are defined as:

La = KY * KY

Lb = KZ * LZ

The slenderness calculated for the v-v axis is then used to calculate thecompression strength p

cfor the weaker principal axis (z-z for ST angles or y-

y for RA specified angles).  The maximum slenderness of the a-a and b-baxes is used to calculate the compression strength p

cfor the stronger

principal axis.

Alternatively for single angles where the connection is not known or Table25 is not appropriate, by setting the LEG parameter to 10, slenderness iscalculated for the two principal axes y-y and z-z only.  The LVV parameter isnot used.

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For double angles, the LVV parameter is available to comply with note 5 intable 25. In addition, if using double angles from user tables, (TechnicalReference Manual section 5.19) an eleventh value, r

vv, should be supplied at

the end of the ten existing values corresponding to the radius of gyration ofthe single angle making up the pair.

3. PY – Steel Design Strength

The design parameter PY should only be used when a uniform designstrength for an entire structure or a portion thereof is required. Otherwise thevalue of PY will be set according to the stipulations of BS5950 table 9 inwhich the design strength is seen as a function of cross sectional thickness fora particular steel grade (SGR parameter) and particular element considered.Generally speaking this option is not required and the program should beallowed to ascertain the appropriate value.

4. UNL, LY, and LZ – Relevant Effective Length

The values supplied for UNL, LY and LZ should be real numbers greater thanzero in current units of length. They are supplied along with or instead ofUNF, KY and KZ (which are factors, not lengths) to define lateral torsionalbuckling and compression effective lengths respectively. Please note thatboth UNL or UNF and LY or KY values are required even though they are oftenthe same values. The former relates to compression flange restraint for lateraltorsional buckling while the latter is the unrestrained buckling length forcompression checks.

5. TRACK – Control of Output Formats

When the TRACK parameter is set to 0.0, 1.0 or 2.0, member capacities willbe printed in design related output (code check or member selection) inkilonewtons per square metre.

TRACK 4.0 causes the design to carry out a deflection check, usually with adifferent load list to the main code check.  The members that are to bechecked must have the parameters, DFF, DJ1 and DJ2 set.

An example of each TRACK setting follows:

Example output for TRACK 0.0MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/

FX MY MZ LOCATION=======================================================================

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1 ST UC305X305X118 PASS BS-4.3.6 0.769 3179.66 C 0.00 334.46 0.00

Example output for TRACK 1.0MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/

FX MY MZ LOCATION=======================================================================

1 ST UC305X305X118 PASS BS-4.3.6 0.769 3179.66 C 0.00 334.46 0.00

|---------------------------------------------------------------------|| CALCULATED CAPACITIES FOR MEMB 1 UNIT - kN,m SECTION CLASS 1 ||MCZ= 519.4 MCY= 234.3 PC= 2455.9 PT= 0.0 MB= 435.0 PV= 600.1|| BUCKLING CO-EFFICIENTS mLT = 1.00, mx = 1.00, my = 1.00, myx = 1.00 || PZ= 3975.00 FX/PZ = 0.05 MRZ= 516.9 MRY= 234.3 ||---------------------------------------------------------------------|

Example output for TRACK 2.0MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/

FX MY MZ LOCATION=======================================================================

1 ST UC305X305X118 PASS BS-4.3.6 0.769 3179.66 C 0.00 334.46 0.00

=======================================================================MATERIAL DATA

Grade of steel = S 275Modulus of elasticity = 210 kN/mm2Design Strength (py) = 265 N/mm2

SECTION PROPERTIES (units - cm)Member Length = 600.00Gross Area = 150.00 Net Area = 127.50 Eff. Area = 150.00

z-z axis y-y axisMoment of inertia : 27700.004 9060.001Plastic modulus : 1960.000 895.000Elastic modulus : 1761.526 589.460Effective modulus : 1960.000 895.000Shear Area : 103.471 37.740

DESIGN DATA (units - kN,m) BS5950-1/2000Section Class : PLASTICSquash Load : 3975.00Axial force/Squash load : 0.045

z-z axis y-y axisCompression Capacity : 3551.7 2455.9Moment Capacity : 519.4 234.3Reduced Moment Capacity : 516.9 234.3Shear Capacity : 1645.2 600.1

BUCKLING CALCULATIONS (units - kN,m)(axis nomenclature as per design code)

x-x axis y-y axisSlenderness : 44.153 77.203Radius of gyration (cm) : 13.589 7.772

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Effective Length : 6.000 6.000

LTB Moment Capacity (kNm) and LTB Length (m): 435.00, 6.000LTB Coefficients & Associated Moments (kNm):mLT = 1.00 : mx = 1.00 : my = 1.00 : myx = 1.00Mlt = 334.46 : Mx = 334.46 : My = 0.00 : My = 0.00

CRITICAL LOADS FOR EACH CLAUSE CHECK (units- kN,m):

CLAUSE RATIO LOAD FX VY VZ MZ MYBS-4.2.3-(Y) 0.143 3 - 85.6 - - -BS-4.3.6 0.769 3 - 85.6 - 334.5 -BS-4.7 (C) 0.098 1 239.7 - - - -BS-4.8.3.2 0.647 3 179.7 85.6 0.0 334.5 0.0BS-4.8.3.3.1 0.842 3 179.7 - - 334.5 0.0BS-4.8.3.3.2 0.842 3 179.7 - - 334.5 0.0ANNEX I.1 0.714 3 179.7 - - 334.5 0.0Torsion and deflections have not been considered in the design.

6. MX, MY, MYX, and MLT – Equivalent Moment Factors

The values for the equivalent moment factors can either be specified directlyby the user as a positive value between 0.4 and 1.0 for MX, MY and MYX and0.44 and 1.0 for MLT.

The program can be used to calculate the values for the equivalent momentfactors by defining the design member with a GROUP command (see theTechnical Reference Manual section 5.16 Listing of Members/Elements/Jointsby Specification of GROUPS). The nodes along the beam can then be definedas the location of restraint points with J settings.

Additionally for the MLT parameter, the joint can be defined as having theupper flange restrained (positive local Y) with the a U setting or the lowerflange restrained (negative local Y) with a L setting.

For example, consider a series of 5 beam elements as a single continuousmember as shown below:

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To enable the steel design, the beam needs to be defined as a group, calledMainBeam:

START GROUP DEFINITION

MEMBER

_MAINBEAM11 2 38 12 3

END GROUP DEFINITION

Note: This can be done in the User Interface by selecting Tools >Create New Group….

Therefore, this 5 beammember has 6 joints such that:

Joint 1 = Node 3

Joint 2 = Node 1

Joint 3 = Node 33

Joint 4 = Node 14

Joint 5 = Node 7

Joint 6 = Node 2

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a. Consider MX, MY and MYX

Say that this member has been restrained in its’ major axis (local Y) onlyat the ends.  In the minor axis (local Z) it has been restrained at theends and also at node number 33 (joint 3).  For local flexural buckling,it has only been restrained at its ends.  Hence:

For the major axis, local Y axis:

MX _MainBeam J1 J6

For the minor axis, local Z axis:

MY _ MainBeam J1 J3 J6

For the lateral flexural buckling, local X axis:

MYX _ MainBeam J1 J6

b. Consider MLT

Say that this member has been restrained at its’ ends against lateral torsionalbuckling and the top flange has been restrained at node number 33 (joint 3)and only the lower flange at node number 7, (joint 5).  Hence:

MLT _MainBeam J1 T3 L5 J6

To split the beam into two buckling lengths for Lyat joint 14:

MY _groupname J1 J4 J6

7. SWAY – Sway Loadcase

This parameter is used to specify a load case that is to be treated as a swayload case in the context of clause 4.8.3.3.4. This load case would be set up torepresent the k

ampMsmentioned in this clause and the steel design module

would add the forces from this load case to the forces of the other load case itis designed for.

Note that the load case specified with this parameter will not be designed as aseparate load case.  The following is the correct syntax for the parameter:

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ParameterName

Default Value Description

SWAY (load case

number)

ALL

MEMBER (member list)

_(group name)

Example

SWAY5 MEM1 TO10

SWAY6 _MAINBEAMS

2B.7 Design Operations

STAAD contains a broad set of facilities for the design of structural members asindividual components of an analyzed structure. The member design facilitiesprovide the user with the ability to carry out a number of different designoperations. These facilities may be used selectively in accordance with therequirements of the design problem.

The operations to perform a design are:

l Specify the load cases to be considered in the design; the default is all loadcases.

l Specify design parameter values, if different from the default values.

l Specify whether to perform code checking or member selection along withthe list of members.

These operations may be repeated by the user any number of times dependingupon the design requirements.

2B.8 Code Checking

The purpose of code checking is to ascertain whether the provided sectionproperties of the members are adequate. The adequacy is checked as per BS5950.Code checking is done using the forces and moments at specific sections of themembers. If no sections are specified, the program uses the start and end forcesfor code checking.

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When code checking is selected, the program calculates and prints whether themembers have passed or failed the checks; the critical condition of BS5950 code(like any of the BS5950 specifications for compression, tension, shear, etc.); thevalue of the ratio of the critical condition (overstressed for value more than 1.0 orany other specified RATIO value); the governing load case, and the location(distance from the start of the member of forces in the member where the criticalcondition occurs).

Code checking can be done with any type of steel section listed in Section 2B.4 orany of the user defined sections as described in Section 1.7.3 of the TechnicalReference Manual, GENERAL and ISECTION. In BS5950, these will only beconsidered for design as I-shape sections.

Note: PRISMATIC sections are also not acceptable steel sections for design perBS5950 in STAAD.Pro.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

2B.9 Member Selection

STAAD is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section,i.e., the lightest section, which fulfills the code requirements for the specifiedmember. The section selected will be of the same type section as originallydesignated for the member being designed. Member selection can also beconstrained by the parameters DMAX and DMIN, which limits the maximum andminimum depth of the members.

Member selection can be performed with all the types of steel sections with thesame limitations as defined in section 2B.8 Code Checking.

Selection of members, whose properties are originally input from a user createdtable, will be limited to sections in the user table.

Member selection cannot be performed on members whose section properties areinput as prismatic or as above limitations for code checking.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

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2B.10 Tabulated Results of Steel Design

For code checking or member selection, the program produces the results in atabulated fashion. The items in the output table are explained as follows:

a. MEMBER refers to the member number for which the design is performed.

b. TABLE refers to steel section name, which has been checked against the steelcode or has been selected.

c. RESULTS prints whether the member has PASSED or FAILED. If the RESULTis FAIL, there will be an asterisk (*) mark on front of the member.

d. CRITICAL COND refers to the section of the BS5950 code which governs thedesign.

e. RATIO prints the ratio of the actual stresses to allowable stresses for the crit-ical condition. Normally a value of 1.0 or less will mean the member haspassed.

f. LOADING provides the load case number, which governed the design. 

g. FX, MY, and MZ provide the axial force, moment in local Y-axis and themoment in local z-axis respectively. Although STAAD does consider all themember forces and moments (except torsion) to perform design, only FX,MY and MZ are printed since they are the ones which are of interest, in mostcases.

h. LOCATION specifies the actual distance from the start of the member to thesection where design forces govern.

i. TRACK If the parameter TRACK is set to 1.0, the program will block out partof the table and will print the allowable bending capacities in compression(MCY & MCZ) and reduced moment capacities (MRY & MRZ), allowable axialcapacity in compression (PC) and tension (PT) and shear capacity (PV).TRACK 2.0 will produce the design results as shown in section 2B.9.

2B.11 Plate Girders

Sections will be considered for the Plate Girder checks (BS 5950 Section 4.4) if d/t> 70 ε for ‘rolled sections’ or d/t >62 ε for ‘welded sections’.  The parameter SBLTshould be used to identify sections as rolled or welded; see the parameter list formore information.

If the plate girder has intermediate stiffeners, the spacing is set with the PNLparameter.  These are then used to check against the code clauses  ‘4.4.3.2 -

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Minimum web thickness for serviceability’ and ‘4.4.3.3 - Minimum web thickness toavoid compression flange buckling’.   The following printout is then included if aTRACK 2.0 output is selected:

Shear Buckling check is required: Vb = 1070 kN : qw    = 118 N/mm2d   = 900 mm  :   t  =  10 mm   : a  =  200 mm : pyf = 275 N/mm2BS-4.4.3.2 status = PASS        : BS-4.4.3.3 status = PASS 

The section is then checked for shear buckling resistance using clause ‘4.4.5.2 -Simplified method’ and the result is included in the ratio checks.

2B.12 Composite Sections

Sections that have been defined as acting compositely with a concrete flange eitherfrom a standard database section using the CM option, or from a modified userWIDE FLANGE database with the additional composite parameters, cannot bedesigned with BS5950:2000.

2B.13 Design of Tapered Beams

Design Procedure

Sections will be checked as tapered members provided that are defined either as aTapered I section or from a USER table.

Example using a Tapered I section:

UNIT CM

MEMBER PROPERTY

1 TO 5 TAPERED 100 2.5 75 25 4 25 4

Example using a USER table:

START USER TABLE

TABLE 1

UNIT CM

ISECTION

1000MM_TAPER

100 2.5 75 25 4 25 4 0 0 0

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750MM_TAPER

75 2.5 50 25 4 25 4 0 0 0

END

You must specify the effective length of unrestrained compression flange using theparameter UNL.

The program compares the resistance of members with the applied load effects, inaccordance with BS 5950-1:2000. Code checking is carried out for locationsspecified by the user via the SECTION command or the BEAM parameter. Theresults are presented in a form of a PASS/FAIL identifier and a RATIO of load effectto resistance for each member checked. The user may choose the degree of detailin the output data by setting the TRACK parameter.

The beam is designed as other wide flange beams apart from the Lateral TorsionalBuckling check which is replaced by the Annex G.2.2. check.

Design Equations

A beam defined with tapered properties as defined above will be checked as aregular wide flange (e.g., UB or UC), except that the following is used in place ofclause 4.3.6, the lateral torsional buckling check.

Check Moment for Taper Members as per clause G.2.2

The following criterion is checked at each defined check position in the length ofthe member defined by the BEAM parameter.

Mxi≤ M

bi(1 - F

c/Pc)

Where:

Fcis the longitudinal compression at the check location;

Mbiis the buckling resistance moment M

bfrom 4.3.6 for an equivalent

slenderness λTB, see G.2.4.2, based on the appropriate modulus S,

Seff, Z or Z

effof the cross-section at the point i considered;

Mxiis the moment about the major axis acting at the point i

considered;

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Pcis the compression resistance from 4.7.4 for a slenderness λ

TC.y, see

G.2.3, based on the properties of the minimum depth of cross-sectionwithin the segment length L

G.2.3 Slenderness lTC

λTC= yλ

Where:

λ = Ly/ry

Where:

a is the distance between the reference axis and the axis of restraint,

hsis the distance between the shear centers of the flanges;

Lyis the length of the segment;

ryis the radius of gyration for buckling about the minor axis;

x is the torsional index

G.2.4.2 Equivalent slenderness lTB for Taper members

λTB= cn

tνtλ

Where, for a two-flange haunch:

Where:

C is the taper factor, see G.2.5;

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G.2.5 Taper factor

For an I-section with D ≥ 1.2B and x ≥ 20, the taper factor, c, is as follows:

Where:

Dmax

is the maximum depth of cross-section within the length Ly, seeFigure G.3;

Dmin

is the minimum depth of cross-section within the length Ly, seeFigure G.3;

x is the torsional index of the minimum depth cross-section, see4.3.6.8

Otherwise, c is taken as 1.0 (unity).

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British Codes - Design per BS54002C.1 General Comments

Note: BS5400 is an additional code available from Bentley Systems. It does notcome as standard with British versions.

The British Standard, BS5400 adopts the limit state design philosophy and isapplicable to steel, concrete and composite construction. The code is in ten partscovering various aspects of bridge design. The implementation of part 3, Code ofpractice for design of steel bridges, in STAAD is restricted in its scope to simplysupported spans. It is assumed that the depth remains constant and bothconstruction and composite stages of steel I-Sections can be checked. Thefollowing sections describe in more detail features of the design process currentlyavailable in STAAD.

2C.2 Shape  Limitations

The capacity of sections could be limited by local buckling if the ratio of flangeoutstand to thickness is large. In order to prevent this, the code sets limits to theratio as per clause 9.3.2. In the event of exceeding these limits, the design processwill terminate with reference to the clause.

2C.3 Section  Class

Sections are further defined as compact or noncompact. In the case of compactsections, the full plastic moment capacity can be attained. In the case ofnoncompact sections, local buckling of elements may occur prior to reaching thefull moment capacity and for this reason the extreme fibre stresses are limited tofirst yield. In STAAD, section types are determined as per clause 9.3.7 and thechecks that follow will relate to the type of section considered.

2C.4 Moment  Capacity

Lateral torsional buckling may occur if a member has unrestrained elements incompression. The code deals with this effect by limiting the compressive stress to avalue depending on the slenderness parameter which is a modified form of the ratioLe/Ry. Le is the effective length governed by the provision of lateral restraintssatisfying the requirements of clause 9.12.1. Once the allowable compressive stress

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is determined then the moment capacity appropriate to the section type can becalculated. STAAD takes the effective length as that provided by the user,defaulting to the length of the member during construction stage and as zero,assuming full restraint throughout, for the composite stage. The program thenproceeds to calculate the allowable compressive stress based on appendix G7 fromwhich the moment capacity is then determined.

2C.5 Shear  Capacity

The shear capacity, as outlined in clause is a function of the limiting shearstrength, l, which is dependant on the slenderness ratio. STAAD follows theiterative procedure of appendix G8 to determine the limiting shear strength of theweb panel. The shear capacity is then calculated based on the formula given underclause 9.9.2.2.

2C.6 Design Parameters

Available design parameters to be used in conjunction with BS5400 are listed intable 2C.1. Depending on the value assigned to the 'WET' parameter, the users candetermine the stage under consideration. For a composite design check, takinginto consideration the construction stage, two separate analyses are required. Inthe first, member properties are non-composite and the WET parameter is set to1.0 . In the second, member properties should be changed to composite and theWET parameter set to 2.0. Member properties for composite or non-compositesections should be specified from user provided tables (refer to section 5.19 of themanual for specification of user tables). Rolled sections, composite or non-composite, come under WIDE FLANGE section-type and built-up sections underISECTION. When specifying composite properties the first parameter is assigned anegative value and four additional parameters provided giving details of theconcrete section. See user table examples provided. 

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

UNL *MemberLength

Unsupported Length for calculatingallowable compressive bending stress.

Table 2C.1 - BS5400 Design Parameters

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ParameterName

DefaultValue

Description

PY * Set according to Design Strength ofsteel SGR

NSF * 1.0 Net section factor for tensionmembers.

SGR * 0.0 Steel Grade per BS4360

0.0 = Grade 43

1.0 = Grade 50

2.0 = Grade 55

SBLT 0.0 0.0 = Rolled Section

1.0 = Built up Section

MAIN 1.0 1.0 = Grade of concrete 30 N/mm2

2.0 = Grade of concrete 40 N/mm2

3.0 = Grade of concrete 50 N/mm2

WET 0.0 0.0 = Wet stage with no data saved forcomposite stage.

1.0 = Wet stage with data saved forcomposite stage.

2.0 = Composite and wet stagecombined.

3.0 = Composite stage only.

TRACK 1.0 1.0 = Print all member capacities.

0.0 = suppress all member capacities.

BEAM 0.0 MUST BE CHANGED TO 1.0 FOR ALLRUNS

LY * MemberLength

Length to calculate slenderness ratiofor bending about Y-axis.

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ParameterName

DefaultValue

Description

LZ * MemberLength

Length to calculate slenderness ratiofor bending about Z-axis.

KY 1.0 K value for bending about Y-axis.Usually this is minor axis.

KZ 1.0 K value for bending about Z-axis.Usually this is major axis.

STIFF 1.0 Factor of length for panel length in theshear calculation.

* Provided in current unit systems.

2C.7 Composite  Sections

The definition of composite sections has been provided for in the standardsections definition (refer to Section 5.20.1 of the Technical Reference Manual fordetails). This is purely for analysis and for obtaining the right section properties. Ituses the American requirement of 18 times depth (CT) as the effective depth. Formore control with British sections two new options are available in user providedtables.

Wide Flange Composite

Using the standard definition of I sections in WIDE FLANGE, 4 additional valuescan now be provided. The first is the width of concrete to the left of center of thesteel web (b1). The second is the concrete width to the right (b2). The third is theconcrete depth (d1) to be considered. The last is the modular ratio. The abovevalues are accepted in the program by adding a '-' at the first position on the firstline of data. The program now awaits four extra values on line 2 as describedabove. If (-) is provided on the second line the program requires another 2breadths + 1 thickness for the bottom plate.

ISection

The same is true for ISECTION definition in user table.

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Example

UNIT CM

WIDE FLANGE

C45752

-66.5 44.98 .76 15.24 1.09 21345 645 21.3 34.185 33.223

150 150 30 10

ISECTION

PG9144

-92.05 2.15 92.05 42.05 3.66 42.05 3.66 197.9 153.9 1730

40 40 12 1

The larger British sections have been coded as USER TABLES under wide flange andare available on request to any existing user. Please note however that compositedesign is not available in this portion of STAAD.

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British Codes - Design per BS80072D.1 General  Comments

Note: BS8007 is an additional code available from Bentley Systems. It does notcome as standard with British versions.

STAAD has the capability of performing concrete slab design according to BS8007.BS8007 provides recommendations for the design of reinforced concrete structurescontaining aqueous liquids. It is recommended that the design of the structure iscarried out according to BS8110, unless modified by the recommendations given inBS8007.

Please use the following in conjunction with Section 2A of this Manual - BS8110.

2D.2 Design Process

The design process is carried out in three stages.

1. Ultimate Limit States

The program is structured so that ultimate design is first carried out inaccordance with recommendations given in BS8110. All active design loadcases are considered in turn and a tabulated output is printed showingpossible reinforcement arrangements. 12, 16, and 20 mm bars areconsidered with possible spacings from 100,125,150,175, and 200 mm.Within these spacings, the layout providing the closest area of steel is printedunder each bar size. Longitudinal and transverse moments together withcritical load cases for both hogging and sagging moments are also printed.Minimum reinforcement is in any case checked and provided in eachdirection. Wood & Armer moments may also be included in the design.

2. Serviceability Limit States

In the second stage, flexural crack widths under serviceability load cases arecalculated. The first and every other occurring design load case is consideredas a serviceability load case and crack widths are calculated based on barsizes and spacings proposed at the ultimate limit state check.

Crack widths due to longitudinal and transverse moments are calculateddirectly under bars, midway between and at corners. A tabulated output

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indicating critical serviceability load cases and moments for top and bottomof the slab is then produced.

3. Thermal crack widths

Finally thermal, crack width calculations are carried out. Through availableparameters, the user is able to provide information on the type of slab,temperature range and crack width limits.

Surface zone depths are determined based on the type of slab and critical areas ofreinforcements are calculated and printed in a tabulated form.

Four bar sizes are considered and for each, max crack spacing, Smax and crackwidths are calculated for the critical reinforcements and printed under each barsize.

Maximum bar spacing to limit crack widths to the user's limit is also printed undereach bar size.

2D.3 Design Parameters

The program contains a number of parameters which are needed to perform andcontrol the design to BS8007.

These parameters not only act as a method to input required data for codecalculations but give the Engineer control over the actual design process. Defaultvalues of commonly used values for conventional design practice have beenchosen as the basis. Table 2D.1 contains a complete list of available parameterswith their default values.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

Parameter Name Default Value Description

FC * 30 N/mm2 Concrete grade.

CLEAR * 20 mm Distance from the outer surface to the edge of the bar. This is considered the same onboth surfaces.

SRA 0.0 Orthogonal reinforcement layout without considering torsional moment Mxy - slabs on -500.orthogonal reinforcement layout with Mxy used to calculate WOOD &ARMER moments

Table 2D.1 - BS8007 Design Parameters

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Parameter Name Default Value Description

for design.

A* Skew angle considered in Wood & Armer equations. A* is any angle in degrees.

SCON 1 Parameter which indicates the type of slab ee. ground or suspended as defined inBS8007

1 = Suspended Slab

2 = Ground Slab

TEMP 30°C Temperature range to be considered in thermal crack width calculations

CRACK * * 0.2 mm Limiting thermal crack width

* Provided in current unit systems

2D.4 Structural  Model

Structural slabs that are to be designed to BS8007 must be modeled using finiteelements. Refer to Section 1.6 of the Technical Reference Manual for informationon the sign convention used in the program for defining elements

It is recommended to connect elements in such a way that the positive local z axispoints outwards away, from the center of the container. In this manner the "Top" ofelements will consistently fall on the outer surface and internal pressure loads willact in the positive direction of the local z axis.

An example of a rectangular tank is provided to demonstrate the above procedure.

Element properties are based on the thickness given under ELEMENT PROPERTIEScommand. The following example demonstrates the required input for a 300 mmslab modeled with ten elements.

UNIT MM

ELEMENT PROPERTIES

1 TO 10 THI 300.0

2D.5 Wood & Armer Moments

This is controlled by the SRA parameter. If the default value of zero is used, thedesign will be based on the Mx and My moments which are the direct results of

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STAAD analysis. The SRA parameter (Set Reinforcement Angle) can bemanipulated to introduce Wood & Armer moments into the design replacing thepure Mx, My moments. These new design moments allow the Mxy moment to beconsidered when designing the section. Orthogonal or skew reinforcement may beconsidered. SRA set to -500 will assume an orthogonal layout. If however a skewis to be considered, an angle is given in degrees, measured between the localelement x axis anti-clockwise (positive). The resulting Mx* and My* moments arecalculated and shown in the design format.

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British Codes - Design per British Cold FormedSteel Code

2E.1 General 

Provisions of BS 5950-5:1998, have been implemented. The program allowsdesign of single (non-composite) members in tension, compression, bending,shear, as well as their combinations. Cold work of forming strengthening effectshave been included as an option.

2E.2 Cross-Sectional  Properties

The user specifies the geometry of the cross-section by selecting one of the sectionshape designations from the Gross Section Property Tables published in the “TheSteel Construction Institute”, (Design of Structures using Cold Formed SteelSections).

The Tables are currently available for the following shapes:

l Channel with Lips

l Channel without Lips

l Z with Lips

l Pipe

l Tube

Shape assignment may be done using the General | Property page of the graphicaluser interface (GUI) or by specifying the section designation symbol in the inputfile.

The properties listed in the tables are gross section properties. STAAD.Pro usesunreduced section properties in the structure analysis stage. Both unreduced andeffective section properties are used in the design stage, as applicable.

2E.3 Design Procedure

The following two design modes are available:

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1. Code Checking

The program compares the resistance of members with the applied loadeffects, in accordance with BS 5950-5:1998. Code checking is carried out forlocations specified by the user via the SECTION command or the BEAMparameter. The results are presented in a form of a PASS/FAIL identifier anda RATIO of load effect to resistance for each member checked. The user maychoose the degree of detail in the output data by setting the TRACKparameter.

Refer to Section 2.5 of the Technical Reference Manual for generalinformation on Code Checking. Refer to Section 5.48.2 of the TechnicalReference Manual for details the specification of the Code Checkingcommand.

2. Member Selection

The user may request that the program search the cold formed steel shapesdatabase (BS standard sections) for alternative members that pass the codecheck and meet the least weight criterion. In addition, a minimum and/ormaximum acceptable depth of the member may be specified. The programwill then evaluate all database sections of the type initially specified (i.e.,channel, angle, etc.) and, if a suitable replacement is found, presents designresults for that section. If no section satisfying the depth restrictions orlighter than the initial one can be found, the program leaves the memberunchanged, regardless of whether it passes the code check or not.

Refer to Section 2.6 of the Technical Reference Manual for generalinformation on Member Selection. Refer to Section 5.48.3 of the TechnicalReference Manual for details the specification of the Member Selectioncommand.

The program calculates effective section properties in accordance with Section 4 ofthe subject code. Cross-sectional properties and overall slenderness of membersare checked for compliance with:

l Clause 6.2.2, Maximum Effective Slenderness Ratio for members inCompression

l Clause 4.2, Maximum Flat Width Ratios for Elements in Compression

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2E.4 Design Equations

Tensile Strength

The allowable tensile strength, as calculated in STAAD as per BS5950-5, section 7is described below.

The tensile strength, Ptof the member should be determined from clause 7.2.1

Pt= A

epy

Where:

Ae is the net area An determined in accordance with cl.3.5.4

pyis the design strength

Combined bending and tension

As per clause 7.3 of BS 5950-5:1998 members subjected to both axial tension andbending should be proportioned such that the following relationships are satisfiedat the ultimate limit state

Ft/Pt+ M

z/M

cz+ M

y/M

cy≤ 1

Mz/M

cz≤ 1

and

My/M

cy≤ 1

Where

Ftis the applies tensile strength

Ptis the tensile capacity determined in accordance with clause 7.2.1 of

the subject code

Mz,My,Mcz,Mcyare as defined in clause 6.4.2 of the subject code

Compressive Strength

The allowable Compressive strength, as calculated in STAAD as per BS5950-5,section 6 is described below

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For sections symmetrical about both principal axes or closed cross-sections whichare not subjected to torsional flexural buckling, the buckling resistance under axialload, Pc, may be obtained from the following equation as per clause 6.2.3 of thesubject code

For Sections symmetrical about a single axis and which are not subject to torsionalflexural buckling, the buckling resistance under axial load, Pc, may be obtainedfrom the following equation as per clause 6.2.4 of the subject code

Where the meanings of the symbols used are indicated in the subject clauses.

Torsional flexural buckling

Design of the members which have at least one axis of symmetry, and which aresubject to torsional flexural buckling  should be done according to the stipulationsof the clause 6.3.2 using factored slenderness ratio αL

E/r in place of actual

slenderness ratio while reading Table 10 for  the value of Compressivestrength(p

c).

Where:

α = (PE/PTF) when P

E> P

TF

α = 1, otherwise

Where the meanings of the symbols used are indicated in the subject clause.

Combined bending and compression

Members subjected to both axial compression and bending should be checked forlocal capacity and overall buckling

Local capacity check as per clause 6.4.2 of the subject code

Fc/Pcs+ M

z/M

cz+ M

y/M

cy≤ 1

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Overall buckling check as per clause 6.4.3 of the subject code

For Beams not subjected to lateral buckling, the following relationship should besatisfied

For Beams subjected to lateral buckling, the following relationship should besatisfied

Fcis the applied axial load

Pcsis the short strut capacity as per clause 6.2.3

Mzis the applied bending moment about z axis

Myis the applied bending moment about y axis

Mczis the moment capacity in bending about the local Z axis in the

absence of Fcand M

y, as per clause 5.2.2 and 5.6

Mcyis the moment capacity in bending about the local Y axis, in the

absence of Fcand M

z,as per clause 5.2.2 and 5.6

M-bis the lateral buckling resistance moment as per clause 5.6.2

PEzis the flexural buckling load in compression for bending about the

local Z axis

PEyis the flexural buckling load in compression for bending about the

local Y axis

Cbz,Cby are  taken as unity unless their values are specified by the user

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The Mcz,Mcyand M

b are calculated from clause numbers 5.2.2 and 5.6 in

the manner described herein below.

Calculation of moment capacities

For restrained beams, the applied moment based on factored loads should not begreater then the bending moment resistance of the section, M

c

Mcz= S

zzx p

o

Mcy= S

yyx p

o

Where

Mczis the Moment resistance of the section in z axis

Mczis the Moment resistance of the section in z axis

po is the limiting stress for bending elements under stress gradient and

should not greater then design strength py

For unrestrained beams the applied moment based on factored loads should notbe greater than the smaller of the bending moment resistance of the section , M

c,

and the buckling resistance moment of the beam, Mb

Then buckling resistance moment, Mb,may be calculated as follows

φB= [M

y+ (1 + η)M

E]/2

MYis the yield moment of the section , product of design strength p

yand elastic modules of the gross section with respect to thecompression  flange Zc

MEis the elastic lateral buckling resistance as per clause 5.6.2.2

η is the Perry coefficient

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Please refer clause numbers 5.2.2 and 5.6 of the subject code for a detaileddiscussion regarding the parameters used in the abovementioned equations.

Shear Strength

The maximum shear stress should not be greater then 0.7 ´ pyas per clause 5.4.2

The average shear stress should not exceed the lesser of the shear yield strength,pvor the shear buckling strength, q

cras stipulated in clause 5.4.3 of the subject

code.

The parameters are calculated as follows :

pv= 0.6·p

y

qcr= (1000·t/D)2 N/mm2

Pv= A·min(p

v, qcr)

Where:

Pvis the shear capacity in N/mm2

pyis the design strength in N/mm2

t is the web thickness in mm

D is the web depth in mm

Combined bending and Shear

For beam webs subjected to both bending and shear stresses the member shouldbe designed to satisfy the following relationship as per the stipulations of clause5.5.2 of the subject code

(Fv/Pv)2 + (M/M

c)2 ≤ 1

Where:

Fvis the shear force

M is the bending moment acting at the same section as Fv

Mcis the moment capacity determined in accordance with 5.2.2

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2E.5 Design Parameters

The design parameters outlined in Table 2E.1 are used to control the designprocedure. These parameters communicate design decisions from the engineer tothe program and thus allow the engineer to control the design process to suit anapplication's specific needs.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements, some or all of these parameter values may be changed to exactlymodel the physical structure.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

Parameter Name Default Value Description

CODE BS5950 COLD Design Code to follow.

See section 5.48.1 of theTechnical ReferenceManual.

Table 2E.1 - British Cold Formed Steel Design Parameters

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Parameter Name Default Value Description

BEAM 1.0 When this parameter isset to 1.0 (default), theadequacy of the memberis determined bychecking a total of 13equally spaced locationsalong the length of themember. If the BEAMvalue is 0.0, the 13location check is notconducted, and instead,checking is done only atthe locations specified bythe SECTION command(See STAAD manual fordetails. For TRUSSmembers only start andend locations aredesigned.

CMZ 1.0 Coefficient of equivalentuniform bending C

b. See

BS:5950-5:1998,5.6.Used for Combined axialload and bending design.

CMY 1.0 Coefficient of equivalentuniform bending C

b. See

BS:5950-5:1998,5.6.Used for Combined axialload and bending design.

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Parameter Name Default Value Description

CWY 1.0 Specifies whether thecold work of formingstrengthening effectshould be included inresistance computation.See BS:5950-5:1998,3.4

0 – effectshould not beincluded

1 – effectshould beincluded

FLX 1 Specifies whethertorsional-flexuralbuckling restraint isprovided or is notnecessary for themember. See BS:5950-5:1998, 5.6

Values:

0 – Sectionsubject totorsionalflexuralbuckling

1 –  Sectionnot subject totorsionalflexuralbuckling

FU 430 MPa Ultimate tensile strengthof steel in current units.

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Parameter Name Default Value Description

FYLD 250 MPa Yield strength of steel incurrent units.

KX 1.0 Effective length factor fortorsional buckling. It is afraction and is unit-less.Values can range from0.01 (for a columncompletely preventedfrom buckling) to anyuser specified largevalue. It is used tocompute the KL/R ratiofor twisting fordetermining the capacityin axial compression.

KY 1.0 Effective length factor foroverall buckling aboutthe local Y-axis. It is afraction and is unit-less.Values can range from0.01 (for a columncompletely preventedfrom buckling) to anyuser specified largevalue. It is used tocompute the KL/R ratiofor determining thecapacity in axialcompression.

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Parameter Name Default Value Description

KZ 1.0 Effective length factor foroverall buckling in thelocal Z-axis. It is afraction and is unit-less.Values can range from0.01 (for a membercompletely preventedfrom buckling) to anyuser specified largevalue. It is used tocompute the KL/R ratiofor determining thecapacity in axialcompression.

LX Member length Unbraced length fortwisting. It is input in thecurrent units of length.Values can range from0.01 (for a membercompletely preventedfrom torsional buckling)to any user specifiedlarge value. It is used tocompute the KL/R ratiofor twisting fordetermining the capacityin axial compression.

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Parameter Name Default Value Description

LY Member length Effective length foroverall buckling in thelocal Y-axis. It is input inthe current units oflength. Values can rangefrom 0.01 (for a membercompletely preventedfrom buckling) to anyuser specified largevalue. It is used tocompute the KL/R ratiofor determining thecapacity in axialcompression.

LZ Member length Effective length foroverall buckling in thelocal Z-axis. It is input inthe current units oflength. Values can rangefrom 0.01 (for a membercompletely preventedfrom buckling) to anyuser specified largevalue. It is used tocompute the KL/R ratiofor determining thecapacity in axialcompression.

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Parameter Name Default Value Description

MAIN 0 Specify the design forslenderness against themaximum slenderness asper Clause 6.2.2:

0 – Do notcheckslendernessratio

1 – Checkmembersresistingnormal loads(180)

2 - Checkmembersresisting self-weight andwind loads(250)

3 - Checkmembersresistingreversal ofstress (350)

NSF 1.0 Net section factor fortension members

DMAX 2540.0

cm.

Maximum allowabledepth. It is input in thecurrent units of length.

RATIO 1.0 Permissible ratio ofactual to allowablestresses

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Parameter Name Default Value Description

TRACK 0 This parameter is used tocontrol the level of detailin which the designoutput is reported in theoutput file. The allowablevalues are:

0 - Prints onlythe membernumber,section name,ratio, andPASS/FAILstatus.

1 - Prints thedesignsummary inaddition tothat printedby TRACK 1

2 - Printsmember andmaterialproperties inaddition tothat printedby TRACK 2.

2E.5 Verification Problem

Shown below is a verification example for reference purposes.

In this problem, we have assigned Channel sections with lips to different members.Member numbers 28 to 31 have been assigned section 230CLHS66X16,membernumbers 3 TO 6 and 15 TO 19 have been assigned the section 230CLMIL70X30 andmember numbers 1, 2, 7 TO 14 have been assigned the section 170CLHS56X18.These members have been designed as per BS 5950 Part 5. Other sections have

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been assigned from the AISI shapes database  (American cold-formed steel) anddesigned in accordance with that code.

The excerpts from the design output for member number 1 are as follows:

STAAD.PRO CODE CHECKING - (BS5950-5-V1.1)

***********************UNITS : MM, KN, KNM, MPA

-------------------------------------------------------------------------------| MEMBER# 1 SECTION: 170CLHS56X18 LEN: 609.60LOCATION: 609.60 || STATUS: PASS RATIO = 0.278 GOV.MODE: 6.4-BEND + COM-PRESS GOV.LOAD: 1 ||-----------------------------------------------------------------------------|

MATERIAL DATA:YIELD STRENGTH OF STEEL : 379.21 N/MM2ULTIMATE TENSILE STRENGTH : 430.00 N/MM2

SECTION PROPERTIES:(UNITS - CM)SECTION NAME : 170CLHS56X18MEMBER LENGTH : 60.96GROSS AREA(AG) : 5.45 NET AREA

(AE): 4.58Z-Z AXIS Y-Y

AXISMOMENT OF INERTIA (I) : 237.27

21.93MOMENT OF INERTIA (IE) : 235.46

19.42ELASTIC MODULUS (ZET) : 27.85

5.20ELASTIC MODULUS (ZEC) : 27.55

10.42

DESIGN DATA:Z-Z AXIS Y-Y

AXISCOMPRESSION CAPACITY (PC) : 93.70MOMENT CAPACITY (MC) : 9.17

3.47SHEAR CAPACITY (PV) : 21.00

33.50LTB CAPACITY (MB) : 9.17

EACH CLAUSE CHECK UNDER CRITICAL LOAD :CLAUSE COMBINATION RATIOBS-6.3 COMPRESSION RATIO - AXIAL 0.037BS-6.4 BEND-COMPRESSION RATIO 0.278BS-5.1 BENDING RATIO - Z 0.236BS-5.1 BENDING RATIO - Y 0.006BS-5.1 BIAXIAL BENDING RATIO 0.241BS-5.4 SHEAR RATIO - Z 0.168BS-5.4 SHEAR RATIO - Y 0.003BS-5.5.2 BENDING -Z & SHEAR - Y RATIO 0.084

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BS-5.5.2 BENDING -Y & SHEAR - Z RATIO 0.000TORSION AND DEFLECTIONS HAVE NOT BEEN CONSIDERED IN THEDESIGN.

1. Bending Check

As per Clause 5.2.2.2 of BS 5950 –Part 5 the limiting compressive

stress(po) for stiffened webs  is given by  the minimum of

p0= Py, where Py = Min ( FYLD, 0.84·FU) = 361.2 N/mm2

So that

p0= [1.13 - 0.0019·(170/1.8)·(279.212/280)1/2]·361.2 = 332.727 N/mm2

The limiting compressive moments in local Y and Z axes will be given by

Mcz= S

zz·po= 27,632.4(332.727) = 9.19(10)

6N·mm

Mcy= S

yy·po= 27,632.4(5,427.50) = 3.46(10)

6N·mm

Maximum bending moment about local Z = 2159 N·m at node 7

Maximum bending moment about local Y = 19.755 N·m at node 7

Bending Ratio Z = 2.15 X106 / 9.19 X106 = 0.235 ……hence verified

Bending Ratio Y =  19755.3 / 3.46 X106 = 0.0057 ……hence verified

Buckling resistance moment Mb

As per section 5.6.2,

The buckling resistance moment

Where:

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The Yield moment of section is given by

MY= S

zz· p

o= 9.19(10)6 N·mm

The elastic buckling resistance moment as per clause 5.6.2.2 is calculated tobe

 ME= 4.649(10)6 N·mm

And

φB= [M

y+ (1 + η)M

E]/2

So that

φB= [9.19(10)6 + (1 + 0.0)4.649(10)6]/2 = 2.325(10)10

Which yields

Mb= (4.649·106·9.19·106 )/{2.325·1010 + [(2.325·1010)2 -

4.649·106·9.19·106 ]1/2} = 9.98(10)6 N·mm

2. Compression Check

The Axial force induced in member# 1 is  3,436.75 N

The elastic flexural buckling load PE= 1.185(10)6 N

The short strut capacity (Pcs ) is given by

Aeff·py = 457.698(344) = 157,448 N

Perry Coefficient (η) =  0.02074

φ = [Pcs+ (1 + η)P

E]/2 = 683,512.45 N

Buckling resistance

Pc= 153,782 N

For Channel section (being singly symmetric), Buckling Resistance as perclause 6.2.4 is

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Where:

The limiting compressive moment, Mc, in the relevant direction is equal to

9.19(10)6N·mm,as calculated above

And the distance, es, of the geometric neutral axis of the gross cross section

and that of the effective cross section is equal to 38.24 m

So that,

P'c= (9.19·106 ·153,782)/[9.19·106 + 153,782(38.24)] = 93,788.7 N

Compression ratio = 3,436.75/93,788.7 = 0.0366 ……hence verified

3. Axial Compression and Bending

Local capacity check as per clause 6.4.2

Fc/Pcs+ M

z/M

cz+ M

y/M

cy

= 3,436.75/[457.698(379.212)] + 2.15·106/(9.19·106) + 19,755.3/(1.81·106) =0.26

Overall buckling check per 6.4.3

= 0.2773 ……hence verified

4. Shear Check as per clause 5.4.2 and 5.4.3

pv= 0.6·p

y = 0.6(379.212) = 227.52 N/mm2

qcr= (1000·t/D)2 = (1000·1.8/170)2 = 112.11 N/mm2

Pv= A·min(p

v, qcr)

Shear resistance Y = 33,579.4 N

International Design Codes Manual — 141

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Shear resistance Z = 21,148.6 N

Shear Ratio Y = 5,627.72/33,579.4 = 0.1675 ……hence verified

Shear Ratio Z = 5,627.72/21,148.6 = 0.0031 ……hence verified

5. Shear Check with Bending as per clause 5.5.2

Shear with bending on Z

(Fv/Pv)2 + (M

z/M

cz)2 = (5,627.72/33,579.4)2 + [2.15·106 /(9.19·106 )]2 =

0.08327

……hence verified

Shear with bending on Y

(Fv/Pv)2 + (M

y/M

cy)2 = (67.114/21,148.6)2 + [19,755.3/(3.46·106 )]2 =

0.0000427

……hence verified

Input File

STAAD SPACE

SET ECHOOFF

INPUT WIDTH 79

UNIT FEET KIP

JOINT COORDINATES

1 0 5 0; 2 0 5 10; 3 10 5 0; 4 10 5 10; 5 5 5 0; 6 5 5 10; 7 0 5 2; 8 0 54;

9 0 5 6; 10 0 5 8; 11 10 5 2; 12 10 5 4; 13 10 5 6; 14 10 5 8; 15 5 52;

16 5 5 4; 17 5 5 6; 18 5 5 8; 19 10 0 0; 20 10 0 10; 21 0 0 10; 22 0 00;

MEMBER INCIDENCES

1 1 7; 2 3 11; 3 1 5; 4 2 6; 5 5 3; 6 6 4; 7 7 8; 8 8 9; 9 9 10; 10 10 2;

11 11 12; 12 12 13; 13 13 14; 14 14 4; 15 5 15; 16 15 16; 17 16 17;18 17 18;

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19 18 6; 20 7 15; 21 15 11; 22 8 16; 23 16 12; 24 9 17; 25 17 13; 2610 18;

27 18 14; 28 1 22; 29 2 21; 30 3 19; 31 4 20; 32 1 21; 33 21 4; 34 419;

35 19 1; 36 2 20; 37 20 3; 38 3 22; 39 22 2;

MEMBER PROPERTYCOLDFORMED AMERICAN

32 TO 39 TABLE ST 3LU3X060

20 TO 27 TABLE ST 3HU3X075

MEMBER PROPERTYCOLDFORMED BRITISH

28 TO 31 TABLE ST 230CLHS66X16

3 TO 6 15 TO 19 TABLE ST 230CLMIL70X30

1 2 7 TO 14 TABLE ST 170CLHS56X18

UNIT MMS

PRINT MEMBER PROPERTIES LIST 32 20 28 3 1

SUPPORTS

19 TO 22 PINNED

UNIT FEET

DEFINEMATERIAL START

ISOTROPIC STEEL

E 4.176E+006

POISSON 0.3

DENSITY 0.489024

ALPHA 6.5E-006

DAMP 0.03

END DEFINEMATERIAL

CONSTANTS

BETA 90 MEMB 20 TO 27

MATERIAL STEELMEMB 1 TO 39

MEMBER TENSION

32 TO 39

UNIT FEET KIP

International Design Codes Manual — 143

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LOAD 1 VERTICAL AND HORIZONTAL

MEMBER LOAD

3 TO 6 20 TO 27 UNIGY -0.3 0 5

JOINT LOAD

1 2 FX 0.6

2 4 FZ -0.6

PERFORMANALYSIS PRINT STATICS CHECK

UNIT KGS CM

PRINT JOINT DISP LIST 1 4 16

PRINT SUPPORT REACTIONS

PRINT MEMBER FORCES LIST 3 24 28

UNIT KIP INCH

PARAMETER 1

CODE AISI

FYLD 55 ALL

CWY1 ALL

BEAM 1 ALL

TRACK 2 ALL

CHECK CODEMEMB 20 21

PARAMETER 2

CODE BS5950 COLD

TRACK 2 MEMB 1 TO 19 28 TO 31

CHECK CODEMEMB 1 2

FINISH

Resulting Output File

*****************************************************

*

144— STAAD.Pro

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* STAAD.PRO V8I SELECTSERIES2*

* VERSION 20.07.07.27*

* PROPRIETARY PROGRAM OF*

* BENTLEY SYSTEMS, INC.*

* DATE= FEB 9, 2011*

* TIME= 16: 0:53*

**

* USER ID: BENTLEY SYSTEMS*

****************************************************

1. STAAD SPACEINPUT FILE: BRITISH COLD FORMED VERIFICATION.STD

2. SET ECHO OFFSTAAD SPACE

-- PAGE NO. 2MEMBER PROPERTIES. UNIT - CM-----------------MEMB PROFILE AX/ IZ/ IY/

IX/AY AZ SZ

SY32 ST 3LU3X060 2.26 21.81

5.17 0.021.51 1.51

4.05 1.9320 ST 3HU3X075 4.91 63.15

40.66 0.061.24 2.40

10.63 9.5928 ST 230CLHS66X16 8.78 663.30

42.82 0.175.31 2.76

60.05 9.063 ST 230CLMIL70X30

11.40 868.9066.93 0.35

6.61 3.6179.03 13.84

1 ST 170CLHS56X18 5.23 224.5020.49 0.06

2.93 1.7527.47 5.28

************ END OF DATA FROM INTERNAL STORAGE************

P R O B L E M S T A T I S T I C S-----------------------------------

NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS = 22/39/ 4

International Design Codes Manual — 145

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SOLVER USED IS THE IN-CORE ADVANCED SOLVERTOTAL PRIMARY LOAD CASES = 1, TOTAL DEGREES OF FREE-

DOM = 120STAAD SPACE

-- PAGE NO. 3**START ITERATION NO. 2**NOTE-TENSION/COMPRESSION CONVERGED AFTER 2 ITERATIONS,

CASE= 1

STATIC LOAD/REACTION/EQUILIBRIUM SUMMARY FOR CASENO. 1

VERTICAL AND HORIZONTAL

CENTER OF FORCE BASED ON·FORCES ONLY (FEET).(FORCES IN NON-GLOBAL DIRECTIONS WILL INVALIDATE

RESULTS)·= 0.000000000E+00Y = 0.500000015E+01Z = 0.500000015E+01

CENTER OF FORCE BASED ON Y FORCES ONLY (FEET).(FORCES IN NON-GLOBAL DIRECTIONS WILL INVALIDATE

RESULTS)·= 0.500000015E+01Y = 0.500000015E+01Z = 0.500000015E+01

CENTER OF FORCE BASED ON Z FORCES ONLY (FEET).(FORCES IN NON-GLOBAL DIRECTIONS WILL INVALIDATE

RESULTS)·= 0.500000015E+01Y = 0.500000015E+01Z = 0.100000003E+02

***TOTAL APPLIED LOAD ( KIP FEET ) SUMMARY (LOADING1 )

SUMMATION FORCE-X = 1.20SUMMATION FORCE-Y = -18.00SUMMATION FORCE-Z = -1.20SUMMATION OF MOMENTS AROUND THE ORIGIN-MX= 84.00 MY= 12.00 MZ= -

96.00

***TOTAL REACTION LOAD( KIP FEET ) SUMMARY (LOADING1 )

SUMMATION FORCE-X = -1.20SUMMATION FORCE-Y = 18.00SUMMATION FORCE-Z = 1.20SUMMATION OF MOMENTS AROUND THE ORIGIN-MX= -84.00 MY= -12.00 MZ=

96.00STAAD SPACE

-- PAGE NO. 4MAXIMUM DISPLACEMENTS ( INCH /RADIANS) (LOADING 1)

MAXIMUMS AT NODE·= 1.56273E-02 1Y = -4.80478E-01 16Z = -1.74875E-02 4RX= -8.28315E-03 6RY= -2.09547E-05 14

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RZ= -8.32083E-03 7

************ END OF DATA FROM INTERNAL STORAGE************

STAAD SPACE-- PAGE NO. 5

JOINT DISPLACEMENT (CM RADIANS) STRUCTURE TYPE =SPACE

------------------JOINT LOAD X-TRANS Y-TRANS Z-TRANS X-ROTAN Y-ROTAN Z-ROTAN

1 1 0.0397 -0.0184 -0.0339 0.00740.0000 -0.0027

4 1 0.0305 -0.0185 -0.0444 -0.00740.0000 0.0025

16 1 0.0352 -1.2204 -0.0392 0.00250.0000 0.0000

************** END OF LATEST ANALYSIS RESULT**************

STAAD SPACE-- PAGE NO. 6

SUPPORT REACTIONS -UNIT KGS CM STRUCTURE TYPE =SPACE

-----------------JOINT LOAD FORCE-X FORCE-Y FORCE-Z MOM-XMOM-Y MOM Z

19 1 -447.20 2312.64 85.07 0.000.00 0.00

20 1 -446.98 2041.85 186.40 0.000.00 0.00

21 1 174.14 1768.33 187.80 0.000.00 0.00

22 1 175.72 2041.85 85.04 0.000.00 0.00

************** END OF LATEST ANALYSIS RESULT**************

STAAD SPACE-- PAGE NO. 7

MEMBER END FORCES STRUCTURE TYPE = SPACE-----------------ALL UNITS ARE -- KGS CM (LOCAL )MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSIONMOM-Y MOM-Z

3 1 1 669.35 1448.01 2.69 -1.67-214.95 61567.53

5 -669.35 -767.63 -2.69 1.67-195.56 107264.16

24 1 9 -0.62 -0.06 -285.32 -0.04-0.08 0.91

17 0.62 0.06 -395.06 0.04 -8362.12 -9.69

28 1 1 2155.99 -404.01 -85.04 0.0012959.61 -61571.77

22 -2155.99 404.01 85.04 0.000.00 0.00

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************** END OF LATEST ANALYSIS RESULT**************

STAAD SPACE-- PAGE NO. 8

STAAD.PRO CODE CHECKING - (AISI)***********************UNITS ARE: IN, KIP, KIP-IN, KSI

|-----------------------------------------------------------------------------|| MEMBER# 20 SECTION: 3HU3X075 LEN: 60.00GOV.LOC: 60.00 || STATUS: PASS RATIO = 0.285 GOV.MODE: BEND + COMPRESSGOV.LOAD: 1 ||

|| RESISTANCES: AX.TENS: 0.00 ECC.TENS: 0.00COMPRESS: 7.51 || BEND. Z: 28.21 BEND. Y: 30.98 SHEAR Z: 11.76SHEAR Y: 5.88 ||

|| FYLD: 55.00 COLD WORK FYLD: 55.71 FU: 58.00 A:0.76 AE: 0.76 || IZ: 1.5173E+00 IZE: 1.5173E+00 IY: 9.7684E-01IYE: 9.7684E-01 || SZE_T: 6.4841E-01 SZE_C: 6.4841E-01 SYE_T: 5.8539E-01SYE_C: 7.3374E-01 ||-----------------------------------------------------------------------------|

|-----------------------------------------------------------------------------|| MEMBER# 21 SECTION: 3HU3X075 LEN: 60.00GOV.LOC: 0.00 || STATUS: PASS RATIO = 0.284 GOV.MODE: BEND + COMPRESSGOV.LOAD: 1 ||

|| RESISTANCES: AX.TENS: 0.00 ECC.TENS: 0.00COMPRESS: 7.51 || BEND. Z: 28.21 BEND. Y: 30.98 SHEAR Z: 11.76SHEAR Y: 5.88 ||

|| FYLD: 55.00 COLD WORK FYLD: 55.71 FU: 58.00 A:0.76 AE: 0.76 || IZ: 1.5173E+00 IZE: 1.5173E+00 IY: 9.7684E-01IYE: 9.7684E-01 || SZE_T: 1.0115E+00 SZE_C: 1.0115E+00 SYE_T: 7.3374E-01SYE_C: 5.8539E-01 ||-----------------------------------------------------------------------------|

STAAD SPACE-- PAGE NO. 9

STAAD SPACE-- PAGE NO. 10

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STAAD.PRO CODE CHECKING - (BS5950-5-V1.1)

***********************UNITS : MM, KN, KNM, MPA

-------------------------------------------------------------------------------| MEMBER# 1 SECTION: 170CLHS56X18 LEN: 609.60LOCATION: 609.60 || STATUS: PASS RATIO = 0.278 GOV.MODE: 6.4-BEND + COMPRESSGOV.LOAD: 1 ||-----------------------------------------------------------------------------|

MATERIAL DATA:YIELD STRENGTH OF STEEL : 379.21 N/MM2ULTIMATE TENSILE STRENGTH : 430.00 N/MM2

SECTION PROPERTIES:(UNITS - CM)SECTION NAME : 170CLHS56X18MEMBER LENGTH : 60.96GROSS AREA(AG) : 5.45 NET AREA

(AE): 4.58Z-Z AXIS Y-Y

AXISMOMENT OF INERTIA (I) : 237.27 21.93MOMENT OF INERTIA (IE) : 235.46 19.42ELASTIC MODULUS (ZET) : 27.85

5.20ELASTIC MODULUS (ZEC) : 27.55

10.42

DESIGN DATA:Z-Z AXIS Y-Y

AXISCOMPRESSION CAPACITY (PC) : 93.70MOMENT CAPACITY (MC) : 9.17 3.47SHEAR CAPACITY (PV) : 21.00 33.50LTB CAPACITY (MB) : 9.17

EACH CLAUSE CHECK UNDER CRITICAL LOAD :CLAUSE COMBINATION RATIOBS-6.3 COMPRESSION RATIO - AXIAL 0.037BS-6.4 BEND-COMPRESSION RATIO 0.278BS-5.1 BENDING RATIO - Z 0.236BS-5.1 BENDING RATIO - Y 0.006BS-5.1 BIAXIAL BENDING RATIO 0.241BS-5.4 SHEAR RATIO - Z 0.168BS-5.4 SHEAR RATIO - Y 0.003BS-5.5.2 BENDING -Z & SHEAR - Y RATIO 0.084BS-5.5.2 BENDING -Y & SHEAR - Z RATIO 0.000

TORSION AND DEFLECTIONS HAVE NOT BEEN CONSIDERED IN THEDESIGN.--------------------------------------------------------------------------------------------------------------------------------------------------------------| MEMBER# 2 SECTION: 170CLHS56X18 LEN: 609.60LOCATION: 609.60 |

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| STATUS: PASS RATIO = 0.283 GOV.MODE: 6.4-BEND + COM-PRESS GOV.LOAD: 1 ||-----------------------------------------------------------------------------|

STAAD SPACE-- PAGE NO. 11MATERIAL DATA:

YIELD STRENGTH OF STEEL : 379.21 N/MM2ULTIMATE TENSILE STRENGTH : 430.00 N/MM2

SECTION PROPERTIES:(UNITS - CM)SECTION NAME : 170CLHS56X18MEMBER LENGTH : 60.96GROSS AREA(AG) : 5.45 NET AREA

(AE): 4.58Z-Z AXIS Y-Y

AXISMOMENT OF INERTIA (I) : 237.27

21.93MOMENT OF INERTIA (IE) : 235.46

21.93ELASTIC MODULUS (ZET) : 27.85

14.17ELASTIC MODULUS (ZEC) : 27.55

5.41

DESIGN DATA:Z-Z AXIS Y-Y

AXISCOMPRESSION CAPACITY (PC) : 93.70MOMENT CAPACITY (MC) : 9.17

1.80SHEAR CAPACITY (PV) : 21.00

33.50LTB CAPACITY (MB) : 9.17

EACH CLAUSE CHECK UNDER CRITICAL LOAD :CLAUSE COMBINATION RATIOBS-6.3 COMPRESSION RATIO - AXIAL 0.037BS-6.4 BEND-COMPRESSION RATIO 0.283BS-5.1 BENDING RATIO - Z 0.236BS-5.1 BENDING RATIO - Y 0.010BS-5.1 BIAXIAL BENDING RATIO 0.246BS-5.4 SHEAR RATIO - Z 0.168BS-5.4 SHEAR RATIO - Y 0.003BS-5.5.2 BENDING -Z &L SHEAR - Y RATIO

0.084BS-5.5.2 BENDING -Y & SHEAR - Z RATIO 0.000

TORSION AND DEFLECTIONS HAVE NOT BEEN CONSIDERED IN THEDESIGN.-------------------------------------------------------------------------------

STAAD SPACE-- PAGE NO. 12

*********** END OF THE STAAD.PRO RUN***********

**** DATE= FEB 9,2011 TIME= 16: 0:54 ****

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152— STAAD.Pro

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Section 3

Canadian Codes

International Design Codes Manual — 153

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154— STAAD.Pro

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Canadian Codes - Concrete Design per CSAStandard A23.3-94

3A.1 Design Operations

STAAD can perform design of concrete beams, columns and slabs according to CSASTANDARD A23.3-94. Given the dimensions of a section, STAAD will calculate therequired reinforcement necessary to resist the various input loads.

3A.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be designed.

l For Beams - Prismatic (Rectangular, Square & Tee)

l For Columns - Prismatic (Rectangular, Square and Circular)

l For Slabs - 4-noded Plate Elements

3A.3 Member DimensionsConcrete members that are to be designed by STAAD must have certain sectionproperties input under the MEMBER PROPERTIES command. The followingexample demonstrates the required input:

UNIT MM

MEMBER PROPERTIES

1 3 TO 7 9 PRISM YD 450. ZD 300.

11 14 PR YD 300.

In the above input, the first set of members are rectangular (450mm depth and300mmwidth) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with a 300mm diameter

3A.4 Slenderness  Effects  and  Analysis  Con-siderations

STAAD provides the user with two methods of accounting for the slenderness effectin the analysis and design of concrete members. The first method is equivalent tothe procedure presented in CSA STANDARD A23.3-94 Clause 10.13. STAAD

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accounts for the secondary moments, due to axial loads and deflections, when thePDELTA ANALYSIS command is used. After solving for the joint displacements ofthe structure, the program calculates the additional moments induced in thestructure due to the P-Delta effect. Therefore, by performing a P-Delta analysis,member forces are calculated which will require no user modification beforebeginning member design. Refer to Section 5.37.2 of the Technical ReferenceManual for additional details on this analysis facility.

The second method by which STAAD allows the user to account for theslenderness effect is through user supplied moment magnification factors (see theparameter MMAG in Table 3A.1). Here the user approximates the additionalmoment by supplying a factor by which moments will be multiplied beforebeginning member design. This second procedure allows slenderness to beconsidered in accordance with Clause 10.14 of the code.

It should be noted that STAAD does not factor loads automatically for concretedesign. All the proper factored loads must be provided by the user before theANALYSIS specification.

While performing a P-Delta analysis, all load cases must be defined as primaryload cases. If the effects of separate load cases are to be combined, it should bedone either by using the REPEAT LOAD command or by specifying the loadinformation of these individual loading cases under one single load case. Usage ofthe LOAD COMBINATION command will yield incorrect results for P-Delta Analysisin STAAD.Pro.

3A.5 Design Parameters

The program contains a number of parameters which are needed to performdesign per CSA STANDARD A23.3-94. These parameters not only act as a methodto input required data for code calculations but give the engineer control over theactual design process. Default values, which are commonly used numbers inconventional design practice, have been used for simplicity. Table 3A.1 contains alist of available parameters and their default values. It is necessary to declarelength and force units as Millimeter and Newton before performing the concretedesign.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CLB 40mm Clear cover to reinforcing bar at bottomof cross section.

CLS 40mm Clear cover to reinforcing bar along theside of the cross section.

CLT 40mm Clear cover to reinforcing bar at top ofcross section.

DEPTH YD Depth of the concrete member. Thisvalue defaults to YD as provided underMEMBER PROPERTIES.

EFACE 0.0 Face ofSupport

Distance of face of support from endnode of beam. Used for shear and torsioncalculation.

Note: Both SFACE & EFACE must bepositive numbers.

FC 30 N/mm2 Specified compressive strength ofconcrete.

FYMAIN 400N/mm2 Yield Stress for main reinforcing steel.

FYSEC 400 N/mm2 Yield Stress for secondary reinforcingsteel.

MAXMAIN Number 55bar

Maximummain reinforcement bar size.

MINMAIN Number 10bar

Minimummain reinforcement bar size

MINSEC Number 10bar

Minimum secondary (stirrup)reinforcement bar size.

MMAG 1.0 A factor by which the column designmoments will be magnified.

NSECTION 12 Number of equally-spaced sections to be

Table 3A.1 - Canadian Concrete Design CSA-A23.3-94 Parameters

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ParameterName

DefaultValue

Description

considered in finding critical moments forbeam design.

REINF 0.0 Tied Column. A value of 1.0 will meanspiral.

SFACE 0.0 Distance of face of support from startnode of beam. Used for shear and torsioncalculation.

Note: Both SFACE & EFACE must bepositive numbers.

TRACK 0.0 0. Critical Moment will not be printedout with beam design report.

1. Moments will be printed.

WIDTH ZD Width of the concrete member. Thisvalue defaults to ZD as provided underMEMBER PROPERTIES.

3A.6 Beam Design

Beams are designed for flexure, shear and torsion. For all these forces, all activebeam loadings are scanned to create moment and shear envelopes, and locatecritical sections. The total number of sections considered is thirteen (start, end,and 11 intermediate), unless that number is redefined with the NSECTIONparameter.

Design  for  Flexure

Design for flexure is performed per the rules of Chapter 10 of CSA StandardA23.3-94. Maximum sagging (creating tensile stress at the bottom face of thebeam) and hogging (creating tensile stress at the top face) moments are calculatedfor all active load cases at each of the thirteen sections. Each of these sections aredesigned to resist the critical sagging and hogging moments. Currently, design ofsingly reinforced sections only is permitted. If the section dimensions areinadequate as a singly reinforced section, such a message will be printed in the

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output. Flexural design of beams is performed in two passes. In the first pass,effective depths of the sections are determined with the assumption of single layerof assumed reinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database in singleor multiple layers. The entire flexure design is performed again in a second passtaking into account the changed effective depths of sections calculated on the basisof reinforcement provided after the preliminary design. Final provision of flexuralreinforcements are made then. Efforts have been made to meet the guideline forthe curtailment of reinforcements as per CSA Standard A23.3-94. Although exactcurtailment lengths are not mentioned explicitly in the design output (which finallywill be more or less guided by the detailer taking into account other practicalconsiderations), the user has the choice of printing reinforcements provided bySTAAD at 13 equally spaced sections from which the final detailed drawing can beprepared.

The following annotations apply to the output for Beam Design.

1. LEVEL                   -  Serial number of bar level which may contain one or morebar group.

2. HEIGHT                -  Height of bar level from the bottom of beam.

3. BAR INFOrmation -  Reinforcement bar information specifying number of barsand size.

4. FROM                    -  Distance from the start of the beam to the start of therebar.

5. TO                         -  Distance from the start of the beam to the end of therebar.

6. ANCHOR               -  States whether anchorage, either a hook

(STA,END)                 or continuation, is needed at start (STA) or at the end(END) of the bar.

Design  for  Shear  and  Torsion

Design for shear and torsion is performed per the rules of Chapter 11 of CSAStandard A23.3-94. Shear reinforcement is calculated to resist both shear forcesand torsional moments. Shear design is performed at the start and end sections.The location along the member span for design is chosen as the effective depth +SFACE at the start, and effective depth + EFACE at the end. The load case whichgives rise to the highest stirrup area for shear & torsion is chosen as the critical

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one. The calculations are performed assuming 2-legged stirrups will be provided.The additional longitudinal steel area required for torsion is reported.

The stirrups are assumed to be U-shaped for beams with no torsion, and closedhoops for beams subjected to torsion.

Example of Input Data for Beam Design

UNIT NEWTON MMS

START CONCRETEDESIGN

CODE CANADA

FYMAIN 415 ALL

FYSEC 415 ALL

FC 35 ALL

CLEAR 25 MEMB 2 TO 6

MAXMAIN 40 MEMB 2 TO 6

TRACK 1.0 MEMB 2 TO 9

DESIGN BEAM 2 TO9

END CONCRETEDESIGN

3A.7 Column Design

Column design is performed per the rules of Chapters 7 & 8 of the CSA StandardA23.3-94. Columns are designed for axial force and biaxial moments at the ends.All active loadings are tested to calculate reinforcement. The loading whichproduces maximum reinforcement is called the critical load. Column design is donefor square, rectangular and circular sections. For rectangular and square sections,the reinforcement is always assumed to be equally distributed on each side. Thatmeans the total number of bars will always be a multiple of four (4). This maycause slightly conservative results in some cases.

Example of Input Data for Column Design

UNIT NEWTON MMS

START CONCRETEDESIGN

CODE CANADIAN

FYMAIN 415 ALL

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FC 35 ALL

CLEAR 25 MEMB 2 TO 6

MAXMAIN 40 MEMB 2 TO 6

DESIGN COLUMN 2 TO6

END CONCRETEDESIGN

3A.8 Slab/Wall  Design

To design a slab or wall, it must be modeled using finite elements. The commandsfor specifying elements are in accordance with the relevant sections of the TechnicalReference Manual.

Elements are designed for the moments Mx and My using the same principles asthose for beams in flexure. The width of the beam is assumed to be unity for thispurpose. These moments are obtained from the element force output (see Section3.8 of the Technical Reference Manual). The reinforcement required to resist Mxmoment is denoted as longitudinal reinforcement and the reinforcement required toresist My moment is denoted as transverse reinforcement. The effective depth iscalculated assuming #10 bars are provided. The parameters FYMAIN, FC, CLT, andCLB listed in Table 3A.1 are relevant to slab design. Other parameters mentioned inTable 3A.1 are not applicable to slab design. The output consists only of area ofsteel required. Actual bar arrangement is not calculated because an element mostlikely represents just a fraction of the total slab area.

Figure 3.1 - Element moments: Longitudinal (L) and Transverse (T)

Example of Input Data for Slab/Wall Design

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UNIT NEWTON MMS

START CONCRETEDESIGN

CODE CANADA

FYMAIN 415 ALL

FC 35 ALL

CLB 40 ALL

DESIGN ELEMENT 15 TO 20

END CONCRETEDESIGN

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Canadian Codes - Steel Design per CSA Stand-ard CAN/CSA-S16-01

3B.1 General Comments

The design of structural steel members in accordance with the specificationCAN/CSA S16-01 Limit States Design of Steel Structures is can be used inSTAAD.Pro. This code supercedes the previous edition of the code CAN/CSA –S16.1-94.

The design philosophy embodied in this specification is based on the concept oflimit state design. Structures are designed and proportioned taking intoconsideration the limit states at which they would become unfit for their intendeduse. Two major categories of limit-states are recognized - ultimate andserviceability. The primary considerations in ultimate limit state design are strengthand stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all steelstructures under various loading conditions and at the same time the probability oflimits being surpassed is acceptably low.

In the STAAD.Pro implementation, members are proportioned to resist the designloads without exceeding the limit states of strength, stability and serviceability. Accordingly, the most economic section is selected on the basis of the least weightcriteria as augmented by the designer in specification of allowable member depths,desired section type, or other such parameters. The code checking portion of theprogram checks whether code requirements for each selected section are met andidentifies the governing criteria.

The following sections describe the salient features of the STAAD.Proimplementation of CAN/CSA-S16-01. A detailed description of the design processalong with its underlying concepts and assumptions is available in the specificationdocument.

3B.2 Analysis Methodology

The elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the specified primary and combination loading condition. Youare allowed complete flexibility in providing loading specifications and usingappropriate load factors to create necessary loading situations. Depending uponthe analysis requirements, regular stiffness analysis or P-Delta analysis may be

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specified. Dynamic analysis may also be performed and the results combined withstatic analysis results.

3B.3 Member Property Specifications

For specification of member properties, the steel section library available inSTAAD.Pro may be used. The next section describes the syntax of commands usedto assign properties from the built-in steel table. Member properties may also bespecified using the User Table facility. For more information on these facilities,refer to the STAAD.Pro Technical Reference Manual.

3B.4 Built-in Steel Section Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, the properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredduring the analysis of these members.

Almost all Canadian steel sections are available for input. A complete listing of thesections available in the built-in steel section library may be obtained by using thetools of the graphical user interface.

Following is the description of the different types of sections available:

Welded Wide Flanges (WW shapes)

Welded wide flange shapes listed in the CSA steel tables can be designated usingthe same scheme used by CSA. The following example illustrates the specificationof welded wide flange shapes.

100 TO 150 TA ST WW400X444

34 35 TA ST WW900X347

Wide Flanges (W shapes)

Designation of wide flanges in STAAD is the same as that in CSA tables. Forexample,

10 TO 75 95 TO 105 TA ST W460X106

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100 TO 200 TA ST W610X101

S, M, HP shapes

In addition to welded wide flanges and regular wide flanges, other I shapedsections like S, M and HP shapes are also available. The designation scheme isidentical to that listed in the CSA tables. While specifying the sections, it should beremembered that the portion after the decimal point should be omitted. Thus,M310X17.6 should be specified as M310X17 and S180X22.8 should be specified asS180X22. Examples illustrating specifications of these shapes are provided below.

10 TO 20 BY 2 TA ST S510X98

45 TO 55 TA ST M150X6

88 90 96 TA ST HP310X79

Channel Sections (C &MC shapes)

C and MC shapes are designated as shown in the following example. As in S, M andHP sections, the portion after the decimal point must be omitted in sectiondesignations. Thus, MC250X42.4 should be designated as MC250X42.

55 TO 90 TA ST C250X30

30 TO 45 TA ST MC200X33

Double Channels

Back-to-back double channels, with or without spacing between them, are specifiedby preceding the section designation by the letter D. For example, a back-to-backdouble channel section C200X28 without any spacing in between should bespecified as:

100 TO 120 TA D C200X28

If a spacing of 2.5 length units is used, the specification should be as follows:

100 TO 120 TA D C200X28 SP 2.5

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Note that the specification SP after the section designation is used for providingthe spacing. The spacing should always be provided in the current length unit.

Angles

To specify angles, the angle name is preceded by the letter L. Thus, a 200X200angle with a 25mm thickness is designated as L200X200X25. The followingexamples illustrate angle specifications.

75 TO 95 TA ST L100X100X8

33 34 35 TA ST L200X100X20

Note that the above specification is for “standard” angles. In this specification, thelocal z-axis (see Fig. 2.6 in the Technical Reference Manual) corresponds to the Y’-Y’ axis shown in the CSA table. Another common practice of specifying anglesassumes the local y-axis to correspond to the Y’-Y’ axis. To specify angles inaccordance with this convention, the reverse angle designation facility has beenprovided. A reverse angle may be specified by substituting the word ST with theword RA. Refer to the following example for details.

10 TO 15 TA RA L55X35X4

The local axis systems for STANDARD and REVERSE angles is shown in Fig. 2.6 ofthe STAAD Technical Reference manual.

Double Angles

To specify double angles, the specification ST should be substituted with LD (forlong leg back-to-back) or SD (short leg back-to-back). For equal angles, either SDor LD will serve the purpose. Spacing between angles may be provided by usingthe word SP followed by the value of spacing (in current length unit) after sectiondesignation.

25 35 45 TA LD L150X100X16

80 TO 90 TA SD L125X75X6 SP 2.5

The second example above describes a double angle section consisting of125X75X6 angles with a spacing of 2.5 length units.

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Tees

Tee sections obtained by cutting W sections may be specified by using the Tspecification instead of ST before the name of the W shape. For example:

100 TO 120 TA T W200X42

will describe a T section cut from a W200X42 section.

Rectangular Hollow Sections

These sections may be specified in two possible ways. Those sections listed in theCSA tables may be specified as follows.

55 TO 75 TA ST TUB80X60X4

In addition, any tube section may be specified by using the DT(for depth), WT(forwidth), and TH(for thickness) specifications.

For example:

100 TO 200 TA ST TUBEDT 8.0WT 6.0 TH 0.5

will describe a tube with a depth of 8 in., width of 6 in. and a wall thickness of 0.5inches. Note that the values of depth, width and thickness must be provided incurrent length unit.

Circular Hollow Sections

Sections listed in the CSA tables may be provided as follows:

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15 TO 25 TA ST PIP33X2.5

In addition to sections listed in the CSA tables, circular hollow sections may bespecified by using the OD (outside diameter) and ID (inside diameter)specifications. For example:

70 TO 90 TA ST PIPE OD 10.0 ID 9.0

will describe a pipe with an outside diameter of 10 length units and insidediameter of 9.0 length units. Note that the values of outside and inside diametersmust be provided in terms of current length unit.

Sample input file to demonstrate usage of Canadian shapes

STAAD SPACE

UNIT METER KNS

JOINT COORD

1 0 0 0 17 160 0 0

MEMBER INCIDENCES

1 1 2 16

UNIT CM

MEMBER PROPERTIES CANADIAN

* W SHAPES

1 TA ST W250X18    

* WWSHAPES

2 TA ST WW700X185 

* S SHAPES

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3 TA ST S200X27    

* M SHAPES

4 TA ST M130X28   

* HP SHAPES

5 TA ST HP310X132 

* MC CHANNELS

6 TA ST MC150X17   

* C CHANNELS

7 TA ST C180X18   

* DOUBLE CHANNELS

8 TA D C250X37 SP 1.0

* ANGLES

9 TA ST L55X35X5      

* REVERSE ANGLES

10 TA RA L90X75X5   

* DOUBLE ANGLES, LONG LEG BACK TOBACK

11 TA LD L100X90X6 SP 2.0

* DOUBLE ANGLES, SHORT LEG BACK TOBACK

12 TA SD L125X75X6 SP 2.5

* TUBES

13 TA ST TUB120807  

* TUBES

14 TA ST TUBEDT 16.0WT 8.0 TH 0.8

* PIPES

15 TA ST PIP273X6.3     

* PIPES

16 TA ST PIPE OD 16.0 ID 13.0

PRINT MEMBER PROPERTIES

FINISH

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3B.5 Section Classification

The CSA specification allows inelastic deformation of section elements. Thus, localbuckling becomes an important criterion. Steel sections are classified as plastic(Class 1), compact (Class 2), noncompact (Class 3), or slender element (Class 4)sections depending upon their local buckling characteristics (See Clause 11.2 andTable 1 of CAN/CSA-S16-01). This classification is a function of the geometricproperties of the section. The design procedures are different depending on thesection class. STAAD.Pro determines the section classification for the standardshapes and user specified shapes.

Note: The design of Class 4 sections requires STAAD.Pro V8i (SELECTseries2) build 2007.07 or higher. Otherwise, design is performed for sections thatfall into the category of Class 1,2 or 3 sections only.

3B.6 Member Resistances

The member resistances are calculated in STAAD.Pro according to the proceduresoutlined in section 13 of the specification. These depend on several factors such asmembers unsupported lengths, cross-sectional properties, slenderness factors,unsupported width to thickness ratios and so on. Note that the programautomatically takes into consideration appropriate resistance factors to calculatemember resistances. Explained here is the procedure adopted in STAAD.Pro forcalculating the member resistances.

Note: The design of Class 4 sections requires STAAD.Pro V8i (SELECTseries2) build 2007.07 or higher.

Nomenclature

A = Area.

Ae= Effective area.

Af= Area of flange.

Aw= Area of web.

be= Effective Flange width.

Cf= Compressive force in a member or component under factored load.

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Cr= Factored compressive resistance.

Cw= Warping torsional constant.

Cy= Axial compressive load at yield stress.

D = Outside diameter of pipe section.

E = Elastic modulus of steel.

Fe= Elastic critical buckling stress.

Fy= Yield strength.

Fye= Effective yield stress of section in compression to account for elastic local

buckling.

h = Clear depth of web.

K = Effective length factor.

L = Length or span of member.

Mf= Bending moment in a member or component under factored load.

Mr= Factored moment resistance of a member.

My= Yield moment resistance.

S = Elastic section modulus.

Se= Effective section modulus.

W = Web thickness.

λ = Non-dimensional slenderness parameter in column formula.

λye= Effective non-dimensional slenderness parameter in column formula

considering effective yield stress.

ϕ = Resistance factor

Axial Tension

The criteria governing the capacity of tension members is based on two limit states.The limit state of yielding in the gross section is intended to prevent excessiveelongation of the member. The second limit state involves fracture at the sectionwith the minimum effective net area. The net section area may be specified by the

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user through the use of the parameter NSF (see Table 3B.1). STAAD calculates thetension capacity of a member based on these two limits states per Cl.13.2 ofCAN/CSA-S16-01. Parameters FYLD, FU, and NSF are applicable for thesecalculations.

Axial Compression

The compressive resistance of columns is determined based on Clause 13.3 of thecode. The equations presented in this section of the code assume that thecompressive resistance is a function of the compressive strength of the grosssection (Gross section Area times the Yield Strength) as well as the slendernessfactor (KL/r ratios). The effective length for the calculation of compressionresistance may be provided through the use of the parameters KT, KY, KZ, LT, LY,and LZ (see Table 3B.1). Some of the aspects of the axial compression capacitycalculations are :

1. For frame members not subjected to any bending, and for truss members,the axial compression capacity in general column flexural buckling iscalculated from Cl.13.3.1 using the slenderness ratios for the local Y-Y andZ-Z axis. The parameters KY, LY, KZ and LZ are applicable for this.

2. For single angles, which are frame members not subjected to any bending ortruss members, the axial compression capacity in general column flexuralbuckling and local buckling of thin legs is calculated using the rules of theAISC - LRFD code, 2nd ed., 1994. The reason for this is that the Canadiancode doesn’t provide any clear guidelines for calculating this value. Theparameters KY, LY, KZ, and LZ are applicable for this.

3. The axial compression capacity is also calculated by taking flexural-torsionalbuckling into account. The rules of Appendix D, page 1-109 of CAN/CSA-S16-01are used for this purpose. Parameters KT and LT may be used toprovide the effective length factor and effective length value for flexural-torsional buckling. Flexural-torsional buckling capacity is computed forsingle channels, single angles, Tees and Double angles.

4. The variable “n” in Cl.13.3.1 is assumed as 2.24 for WWF shapes and 1.34for all other shapes.

5. While computing the general column flexural buckling capacity of sectionswith axial compression + bending, the special provisions of 13.8.1(a),

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13.8.1(b) and 13.8.1(c) are applied. For example, Lambda = 0 for 13.8.1(a),K=1 for 13.8.1(b), etc.)

For Class 4 members subjected to axial compression, factored compressiveresistance should be determined by either of the following equations.

a. Cr= ϕA

eFy(1+λ2n )-1⁄n

Where:

n = 1.34

λ = √(Fy/Fe)

Fe=(π2 E)/(KL/r)2

Ae is calculated using reduced element widths meeting the maximum width tothickness ratio specified in Table 1.

Effective width required for the calculation of effective area Ae, for differentsection shapes are as follows.

l For flanges of I-section, T-section and channel section and legs of anglesection

be= 200t/√((F

y)

l For stem of T-section

be= 340t/√((F

y)

l For flanges of HSS rectangular or Tube sections

be= 670t/√((F

y)

l For circular HSS or Pipe section

D= 23000t/(Fy

b. Cr= ϕAF

ye(1+λ

ye2n )-1⁄n

Where:

n = 1.34

λye= √(F

ye/F_e )

Fe=(π2 E)/(KL/r)2

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With an effective yield stress, Fye, determined from the maximum width (or

diameter)-to-thickness ratio meeting the limit specified in Table 1.

Following are the expressions for effective yield stress for different shapedsection.

l For I-section, T-section, channel section and angle section

Fye= 40000/(b/t)2

l For rectangular HSS section

Fye= 448900/(b/t)2

l For circular HSS section

Fye= 23000/(D/t)

Bending

The laterally unsupported length of the compression flange for the purpose ofcomputing the factored moment resistance is specified in STAAD with the help ofthe parameter UNL. If UNL is less than one tenth the member length (memberlength is the distance between the joints of the member), the member is treated asbeing continuously laterally supported. In this case, the moment resistance iscomputed from Clause 13.5 of the code. If UNL is greater than or equal to onetenth the member length, its value is used as the laterally unsupported length. Theequations of Clause 13.6 of the code are used to arrive at the moment ofresistance of laterally unsupported members. Some of the aspects of the bendingcapacity calculations are :

1. The weak axis bending capacity of all sections except single angles iscalculated as

For Class 1 & 2 sections, φ PyFy

For Class 3 sections, φ SyFy

where

φ = Resistance factor = 0.9

Py= Plastic section modulus about the local Y axis

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Sy= Elastic section modulus about the local Y axis

Fy= Yield stress of steel

2. For single angles, the bending capacities are calculated for the principal axes.The specifications of Section 5, page 6-283 of AISC-LRFD 1994, 2nd ed., areused for this purpose because the Canadian code doesn’t provide any clearguidelines for calculating this value.

3. For calculating the bending capacity about the Z-Z axis of singly symmetricshapes such as Tees and Double angles, CAN/CSA-S16-01 stipulates inClause 13.6(d), page 1-31, that a rational method, such as that given inSSRC’s Guide to Stability Design Criteria of Metal Structures, be used.Instead, STAAD uses the rules of Section 2c, page 6-55 of AISC-LRFD 1994,2nd ed.

Laterally Supported Class 4 members subjected to bending

i. When both the web and compressive flange exceed the limits for Class 3 sec-tions, the member should be considered as failed and an error message willbe thrown.

ii. When flanges meet the requirements of Class 3 but web exceeds the limits forClass 3, resisting moment shall be determined by the following equation.

M_r^'= M_r [1-0.0005 A_w/A_f (h/w-1900/√(M_f⁄ϕS)) ]

Where Mr = factored moment resistance as determined by Clause 13.5 or13.6 but not to exceed ϕMy = factored moment resistance for Class 3 sections= ϕMy

If axial compressive force is present in addition to the moment, modifiedmoment resistance should be as follows.

M_r^'= M_r [1-0.0005 A_w/A_f (h/w-1900(1-0.65 C_f⁄(ϕC_y))/√(M_f⁄ϕS)) ]

Cy = AFy.

S = Elastic section modulus of steel section.

iii. For sections whose webs meet the requirements of Class 3 and whose flangesexceed the limit of Class 3, the moment resistance shall be calculated as

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Mr = ϕSeFy

Where:

Se = effective section modulus determined using effective flangewidth.

l For Rectangular HSS section, effective flange width

b_e= 670t/√(F_y )

l For I-section, T-section, Channel section, effective flange width and forAngle section, effective length width

b_e= 200t/√(F_y )

But shall not exceed 60t.

Laterally Unsupported Class 4 members subjected to bending

As per clause 13.6(b) the moment resistance for class-4 section shall be calculatedas follows

i. When Mu>0.67My

M_r=1.15ϕM_y (1-(0.28M_y)/M_u )

Mr should not exceed ϕSeFy.

ii. When Mu<=0.67My

M_r=ϕM_u

Where, as per clause 13.6(a),

M_u=(ω_2 π)/L √(EI_y GJ+(πE/L)^2 I_y C_w )

For unbraced length subjected to end moments-

ω2=1.75+1.05k+0.3k^2≤2.5

When bending moment at any point within the unbraced length is larger than thelarger end moment or when there is no effective lateral support for thecompression flange at one of the ends of unsupported length-

ω2= 1.0

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k = Ratio of the smaller factored moment to the larger moment at opposite ends ofthe unbraced length, positive for double curvature and negative for singlecurvature.

Se = effective section modulus determined using effective flange width.

l For Rectangular HSS section, effective flange width

b_e= 670t/√(F_y )

l For I-section, T-section, Channel section, effective flange width and for Anglesection, effective length width

b_e= 200t/√(F_y )

But shall not exceed 60t.

This clause is applicable only for I shaped and Channel shaped section as there isno guide line in the code for other sections.

Axial compression and bending

The member strength for sections subjected to axial compression and uniaxial orbiaxial bending is obtained through the use of interaction equations. In theseequations, the additional bending caused by the action of the axial load isaccounted for by using amplification factors. Clause 13.8 of the code provides theequations for this purpose. If the summation of the left hand side of theseequations exceed 1.0 or the allowable value provided using the RATIO parameter(see Table 3B.1), the member is considered to have FAILed under the loadingcondition.

Axial tension and bending

Members subjected to axial tension and bending are also designed usinginteraction equations. Clause 13.9 of the code is used to perform these checks. Theactual RATIO is determined as the value of the left hand side of the criticalequation.

Shear

The shear resistance of the cross section is determined using the equations ofClause 13.4 of the code. Once this is obtained, the ratio of the shear force acting on

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the cross section to the shear resistance of the section is calculated. If any of theratios (for both local Y & Z axes) exceed 1.0 or the allowable value provided usingthe RATIO parameter (see Table 3B.1), the section is considered to have failedunder shear. The code also requires that the slenderness ratio of the web be withina certain limit (See Cl.13.4.1.3, page 1-29 of CAN/CSA-S16-01). Checks for safetyin shear are performed only if this value is within the allowable limit. Users mayby-pass this limitation by specifying a value of 2.0 for the MAIN parameter.

3B.7 Design Parameters

The design parameters outlined in Table 3B.1 may be used to control the designprocedure. These parameters communicate design decisions from the engineer tothe program and thus allow the engineer to control the design process to suit anapplication's specific needs.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements, some or all of these parameter values may be changed to exactlymodel the physical structure.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

Parameter Name Default Value Description

CODE

Table 3B.1 - Canadian Steel Design CSA-S16-01 Parameters

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Parameter Name Default Value Description

BEAM 1.0 0.0  =  designonly for endmoments andthose atlocationsspecified bySECTIONcommand.

1.0  =  Performdesign formoments  attwelfth pointsalong the beam.

CB 1.0 Greater than 0.0and less than 2.5 : Value ofOmega_2(Cl.13.6) to beused forcalculation.

Equal to 0.0 :CalculateOmega_2

CMY 1.0 1.0  =  Do notcalculate Omega-1 for local Y axis.

2.0 = CalculateOmega-1 forlocal Y axis.

Used inCl.13.8.4 ofcode

CMZ 1.0 1.0  =  Do notcalculate Omega-

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Parameter Name Default Value Description

1 for local Z axis.

2.0 = CalculateOmega-1 forlocal Z axis.

Used inCl.13.8.4 ofcode

DFF None(Mandatory for deflection check)

“DeflectionLength”/Maxm.Allowable localdeflection.

DJ1 Start Joint of member Joint No.denoting startpoint forcalculation of“deflectionlength”

DJ2 End Joint of member Joint No.denoting endpoint forcalculation of“deflectionlength”

DMAX 45.0 in. Maximumallowable depth(Applicable formemberselection)

DMIN 0.0 in. Minimumrequired depth(Applicable formemberselection)

FYLD 300.0 MPa Yield strength of

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Parameter Name Default Value Description

steel.

FU 345.0 MPa Ultimate strengthof steel.

KT 1.0 K value forflexural torsionalbuckling.

KY 1.0 K value forgeneral columnflexural bucklingabout the localY-axis. Used tocalculateslendernessratio.

KZ 1.0 K value forgeneral columnflexural bucklingabout the localZ-axis. Used tocalculateslendernessratio.

LT Member Length Length forflexural torsionalbuckling.

LY Member Length Length forgeneral columnflexural bucklingabout the localY-axis. Used tocalculateslendernessratio.

LZ Member Length Length for

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Parameter Name Default Value Description

general columnflexural bucklingabout the localZ-axis. Used tocalculateslendernessratio.

MAIN 0.0 0.0  =  Checkslenderness ratioagainst thelimits.

1.0= Suppressthe slenderness ratio check.

2.0 = Checkslenderness ratioonly for columnbuckling, not forweb (See Section3B.6, Shear)

NSF 1.0 Net sectionfactor for tensionmembers.

RATIO 1.0 Permissible ratioof actual loadeffect to thedesign strength.

TRACK 0.0 0.0 = Reportonly minimumdesign results.

1.0 = Reportdesign strengthsalso.

2.0 = Provide

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Parameter Name Default Value Description

full details ofdesign.

UNB Member Length Unsupportedlength inbendingcompression ofthe bottomflange forcalculatingmomentresistance.

UNT Member Length Unsupportedlength inbendingcompression ofthe top flangefor calculatingmomentresistance.

3B.8   Code  Checking

The purpose of code checking is to check whether the provided section propertiesof the members are adequate. The adequacy is checked as per the CAN/CSA-S16-01  requirements.

Code checking is done using forces and moments at specified sections of themembers. If the BEAM parameter for a member is set to 1, moments are calculatedat every twelfth point along the beam. When no sections are specified and theBEAM parameter is set to zero (default), design will be based on member start andend forces only. The code checking output labels the members as PASSed orFAILed. In addition, the critical condition, governing load case, location (distancefrom the start joint) and magnitudes of the governing forces and moments are alsoprinted. The extent of detail of the output can be controlled by using the TRACKparameter.

Example of commands for CODE CHECKING:

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UNIT NEWTON METER

PARAMETER

CODE CANADIAN

FYLD 330E6 MEMB 3 4

NSF 0.85 ALL

KY 1.2 MEMB 3 4

UNL 15 MEMB 3 4

RATIO 0.9 ALL

CHECK CODEMEMB 3 4

3B.9   Member  Selection

The member selection process basically involves determination of the least weightmember that PASSes the code checking procedure based on the forces andmoments of the most recent analysis. The section selected will be of the same typeas that specified initially. For example, a member specified initially as a channelwill have a channel selected for it. Selection of members whose properties areoriginally provided from a user table will be limited to sections in the user table. Member selection cannot be performed on TUBES, PIPES or members listed asPRISMATIC.

Example of commands for MEMBER SELECTION:

UNIT NEWTON METER

PARAMETER

FYLD 330E6 MEMB 3 4

NSF 0.85 ALL

KY 1.2 MEMB 3 4

UNL 15 MEMB 3 4

RATIO 0.9 ALL

SELECT MEMB 3 4

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3B.10   Tabulated  Results  of  Steel  Design

Results of code checking and member selection are presented in a tabular format.The term CRITICAL COND refers to the section of the CAN/CSA-S16-01specification which governed the design.

If the TRACK parameter is set to 1.0, factored member resistances will be printed.Following is a description of some of the items printed.

CR    =   Factored compressive resistance

TR    =   Factored tensile resistance

VR    =   Factored shear resistance

MRZ =   Factored moment resistance (about z-axis)

MRY =   Factored moment resistance (about y-axis)

Further details can be obtained by setting TRACK to 2.0.

CR1 = CAPACITY (Cr) PER 13.8.2(a)

CR2 = CAPACITY (Cr) PER 13.8.2(b)

CRZ = SEE 13.8.2(b) for uniaxial bending (called CRXin that Clause)

CTORFLX = Capacity in accordance with 13.8.2(c)

3B.11 Verification Problems

In the next few pages are included several verification examples for referencepurposes. Since the S16-01 code is similar in many respects to the previous editionof the code (CAN/CSA S16.1-94), the solved examples of the 1994 edition of theCISC Handbook have been used as reference material for these examples.

Verification  Problem  No.  1

Title

Steel beam with uniform load, wide flange section

Type

Static analysis, 3D beam element.

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Reference

CAN/CSA-S16.1-94, National Standard of Canada, Limit States Design of SteelStructures. The Canadian Standards Association, 1994 with CISC (CanadianInstitute of Steel Construction) handbook. CISC Example 1 page 5_91.

Problem

Find the interaction ratio, beam resistance and beam deflection.

Given

E = 200000 MPa (STEEL)

Fy= 300 Mpa   CSA G40.21-M

Simply supported beam has a 8.0 m span; Ky is 1.0, Kz 1.0, unsupported length1.0 m

Allowable Live Load deflection, L/300 = 8000/300 = 27 mm

Factored Uniform Load IS 7 kN/m DEAD, 15 kN/m LIVE.

Steel section is W410X54

Comparison

Source InteractionRatio

BeamResistance(kN*m)

BeamDeflection(mm)

Reference 0.88 284 21

STAAD.Pro 0.883 283.20 20.81

Table 3B.2 - CAN/CSA-S16 Verification Problem com-parison

****************************************************       *                                                 

*       *           STAAD.PRO                             

*       

186— STAAD.Pro

Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01

Page 197: International Codes v8i

*           VERSION          BLD                  *       

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*           RESEARCH ENGINEERS,  INTL.            *       

*           DATE=                                 *       

      *           TIME=                                 *       

*                                                 *       

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****************************************************       1. STAAD SPACE VERIFICATION CISC 1994 HANDBOOK EXAMPLE

PAGE 5-913. * CISC EXAMPLE 1 PAGE 5-91, LIMIT STATES DESIGN,

CSA-S16.1-944. * SIMPLY SUPPORTED BEAM WITH UNIFORM LOAD5. * LIVE LOAD DEFLECTION OF L/3007. UNIT MMS KN8. JOINT COORDINATES9. 1 0 0 0; 2 8000 0 010. MEMBER INCIDENCES11. 1 1 213. MEMBER PROPERTY CANADIAN14. 1 TABLE ST W410X5416. CONSTANTS17. E STEEL ALL18. POISSON 0.3 ALL20. SUPPORTS21. 1 PINNED22. 2 FIXED BUT MY MZ24. UNIT METER KN25. LOAD 1 DEAD26. MEMBER LOAD27. 1 UNI GY -729. LOAD 2 LIVE30. MEMBER LOAD31. 1 UNI GY -1533. LOAD COMB 3 1.25DL + 1.5 LL34. 1 1.25 2 1.536. PERFORM ANALYSIS

P R O B L E M   S T A T I S T I C S-----------------------------------

NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS =     2/    1/     2

ORIGINAL/FINAL BAND-WIDTH=     1/     1/      5 DOFTOTAL PRIMARY LOAD CASES =    2, TOTAL DEGREES OF FREE-

DOM =      5SIZE OF STIFFNESS MATRIX =        1 DOUBLE  KILO-WORDSREQRD/AVAIL. DISK SPACE  =     12.0/  19641.6 MB37. LOAD LIST 238. PRINT SECTION DISPLACEMENTSMEMBER SECTION DISPLACEMENTS

International Design Codes Manual — 187

Page 198: International Codes v8i

----------------------------UNIT =INCHES FOR FPS AND CM FOR METRICS/SI SYSTEMMEMB  LOAD     GLOBAL X,Y,Z DISPL FROM START TO END

JOINTS AT 1/12TH PTS1     2       0.0000    0.0000    0.0000    0.0000  

-0.5471    0.00000.0000   -1.0528    0.0000    0.0000  

-1.4824    0.00000.0000   -1.8086    0.0000    0.0000  

-2.0120    0.00000.0000   -2.0812    0.0000    0.0000  

-2.0120    0.0000             0.0000   -1.8086    0.0000    0.0000  

-1.4824    0.00000.0000   -1.0528    0.0000    0.0000  

-0.5471    0.00000.0000    0.0000    0.0000

MAX LOCAL  DISP =    2.08115   AT     400.00  LOAD   2   L/DISP=    384

************ END OF SECT DISPL RESULTS ***********40. LOAD LIST 341. PARAMETER42. CODE CANADIAN43. TRACK 2 ALL44. UNL 1 ALL45. FYLD 300000 ALL46. BEAM 1 ALL47. CHECK CODE ALL

STAAD.PRO CODE CHECKING - (CAN/CSA-S16-01)

****************************************** ALL UNITS ARE - KNS  MET  (UNLESS OTHERWISE NOTED) MEMBER     TABLE       RESULT/   CRITICAL COND/    RATIO/     LOADING/

FX            MY             MZ      LOCATION =======================================================================

1 ST   W410X54                  (CANADIAN SECTIONS)PASS     CSA-13.8.2+       

0.883         30.00 C          0.00        -

250.00        4.00MEMBER PROPERTIES (UNIT = CM)-----------------------------CROSS SECTION AREA =  6.84E+01   MEMBER LENGTH = 

8.00E+02IZ =  1.86E+04   SZ =  9.26E+02   PZ =  1.05E+03IY =  1.02E+03   SY =  1.15E+02   PY =  1.77E+02MATERIAL PROPERTIES (UNIT = MPA)--------------------------------FYLD = 300.0   FU = 345.0SECTION CAPACITIES (UNIT - KN,M)---------------------------------CR1 =  1.846E+03   CR2 =  2.732E+02CRZ =  1.570E+03   CTORFLX =  2.732E+02

188— STAAD.Pro

Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01

Page 199: International Codes v8i

TENSILE CAPACITY     =  1.805E+03   COMPRESSIVE CAPACITY=  2.732E+02

FACTORED MOMENT RESISTANCE : MRY =  4.778E+01   MRZ = 2.832E+02

FACTORED SHEAR RESISTANCE  : VRY =  5.379E+02   VRZ = 4.604E+02

MISCELLANEOUS INFORMATION--------------------------NET SECTION FACTOR FOR TENSION =  1.000KL/RY =  207.170   KL/RZ =   48.447   ALLOWABLE KL/R = 

300.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) =  1.000OMEGA-1 (Y-AXIS) = 1.00   OMEGA-1 (Z-AXIS) = 1.00  

OMEGA-2 = 1.00SHEAR FORCE (KNS) : Y AXIS =  0.000E+00   Z AXIS = 

0.000E+00SLENDERNESS RATIO OF WEB (H/W) =  5.08E+0148. STEEL TAKE OFF ALLSTEEL TAKE-OFF--------------PROFILE               LENGTH(METE)      WEIGHT(KN  )IN STEEL TAKEOFF THE DENSITY OF STEEL IS ASSUMED FOR

MEMBERS WITH NO DENSITY.ST  W410X54                   8.00             4.203PRISMATIC STEEL               0.00             0.000

----------------TOTAL =          4.203

************ END OF DATA FROM INTERNAL STORAGE************

49. FINISH

Verification  Problem  No.  2

Title

Steel beam/column, wide flange section.

Type

Static Analysis, 3D beam element.

Reference

CAN/CSA-S16.1-94, National Standard of Canada, Limit States Design of SteelStructures. The Canadian Standards Association, 1994 with CISC (CanadianInstitute of Steel Construction) handbook. CISC Handbook Example, Page 4_106.

International Design Codes Manual — 189

Page 200: International Codes v8i

Problem

Find the interaction ratio, beam and column resistance.

Given

E = 200000 MPa (STEEL).

Fy= 300 MPa   CSA G40.21-M

Simply supported beam/column has a 3.7 m span, Ky is 1.0, Kz 1.0

factored axial load is 2000 kN and end moments of

200 kN*m and 300 kN*m

Steel section is W310X129

Comparison

CAN/CSA-S16

InteractionRatio

BeamResistance

(kN*m)

ColumnResistance

(kN)

REFERENCE 0.96 583 3800

STAAD.Pro 0.98 584 3820

****************************************************       *                                                 

*       *           STAAD.PRO                             

*       *           VERSION          BLD                  

*       *           PROPRIETARY PROGRAM OF                

*       *           RESEARCH ENGINEERS,  INTL.            

*       *           DATE=                                 

*       *           TIME=                                 

*       *                                                 

*  

190— STAAD.Pro

Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01

Page 201: International Codes v8i

*      USER ID:                                   *       

****************************************************       1. STAAD SPACE VERIFICATION CISC 1994 HANDBOOK EXAMPLE

PAGE 4-1062. *3. * COMPRESSION + MAJOR AXIS BENDING4. *5. UNIT METER KN6. JOINT COORDINATES7. 1 0 0 0; 2 0 3.7 08. *9. MEMBER INCIDENCES10. 1 1 211. *12. MEMBER PROPERTY CANADIAN13. 1 TABLE ST W310X12914. *15. CONSTANTS16. E STEEL ALL17. POISSON STEEL ALL18. *19. SUPPORTS20. 1 FIXED BUT MX MZ21. 2 FIXED BUT FY MY MZ22. *23. LOAD 1 FACTORED LOAD24. JOINT LOAD25. 2 FY -200026. 2 MZ 20027. 1 MZ 30028. *29. PDELTA 3 ANALYSIS

P R O B L E M   S T A T I S T I C S-----------------------------------

NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS =     2/    1/     2

ORIGINAL/FINAL BAND-WIDTH=     1/     1/      5 DOFTOTAL PRIMARY LOAD CASES =    1, TOTAL DEGREES OF FREE-

DOM =      5SIZE OF STIFFNESS MATRIX =        1 DOUBLE  KILO-WORDSREQRD/AVAIL. DISK SPACE  =     12.0/  19641.2 MB

++ ADJUSTING DISPLACEMENTS                           8:54:35++ ADJUSTING DISPLACEMENTS                           

8:54:35++ ADJUSTING DISPLACEMENTS                           

8:54:3531. PRINT MEMBER FORCESMEMBER END FORCES    STRUCTURE TYPE = SPACE-----------------ALL UNITS ARE -- KN   METEMEMBER  LOAD  JT     AXIAL   SHEAR-Y  SHEAR-Z   TORSION    MOM-Y      MOM-Z

International Design Codes Manual — 191

Page 202: International Codes v8i

1    1     1   2000.00    135.14     0.00      0.00     0.00     300.00

2  -2000.00   -135.14     0.00      0.00     0.00     200.00************** END OF LATEST ANALYSIS RESULT

**************33. PARAMETER34. CODE CANADIAN35. TRACK 2 ALL36. FYLD 300000 ALL37. LY 3.7 ALL38. LZ 3.7 ALL39. CHECK CODE ALL

STAAD.PRO CODE CHECKING - (CAN/CSA-S16-01)

****************************************** ALL UNITS ARE - KNS  MET  (UNLESS OTHERWISE NOTED) MEMBER     TABLE       RESULT/   CRITICAL COND/    RATIO/     LOADING/

FX            MY             MZ      LOCATION =======================================================================

1 ST   W310X129                 (CANADIAN SECTIONS)                         PASS     CSA-13.8.2C       

0.980         12000.00 C          0.00        

300.00        0.00MEMBER PROPERTIES (UNIT = CM)-----------------------------CROSS SECTION AREA =  1.65E+02   MEMBER LENGTH = 

3.70E+02IZ =  3.08E+04   SZ =  1.94E+03   PZ =  2.16E+03IY =  1.00E+04   SY =  6.51E+02   PY =  9.90E+02MATERIAL PROPERTIES (UNIT = MPA)--------------------------------FYLD = 300.0   FU = 345.0SECTION CAPACITIES (UNIT - KN,M)---------------------------------CR1 =  4.459E+03   CR2 =  3.820E+03CRZ =  4.296E+03   CTORFLX =  3.820E+03TENSILE CAPACITY     =  4.359E+03   COMPRESSIVE CAPACITY

=  3.820E+03FACTORED MOMENT RESISTANCE : MRY =  2.672E+02   MRZ = 

5.840E+02FACTORED SHEAR RESISTANCE  : VRY =  7.419E+02   VRZ = 

1.505E+03MISCELLANEOUS INFORMATION--------------------------NET SECTION FACTOR FOR TENSION =  1.000KL/RY =   47.477   KL/RZ =   27.094   ALLOWABLE KL/R = 

200.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) = 

3.700OMEGA-1 (Y-AXIS) = 1.00   OMEGA-1 (Z-AXIS) = 1.00  

OMEGA-2 = 1.00

192— STAAD.Pro

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Page 203: International Codes v8i

SHEAR FORCE (KNS) : Y AXIS =  1.351E+02   Z AXIS = 0.000E+00

SLENDERNESS RATIO OF WEB (H/W) =  2.12E+0140. STEEL MEMBER TAKE OFF ALLSTEEL TAKE-OFF--------------PROFILE               LENGTH(METE)      WEIGHT(KN  )IN STEEL TAKEOFF THE DENSITY OF STEEL IS ASSUMED FOR

MEMBERS WITH NO DENSITY.ST  W310X129                  3.70             4.694PRISMATIC STEEL               0.00             0.000

----------------                            TOTAL =          4.694

MEMBER      PROFILE           LENGTH        WEIGHT(METE)        (KN  )

1      ST  W310X129               3.70         4.694************ END OF DATA FROM INTERNAL STORAGE

************42. FINISH

Verification  Problem  No.  3

Title

Steel beam/column, wide flange section.

Type

Static Analysis, 3D beam element.

Reference

CAN/CSA-S16.1-94, National Standard of Canada, Limit States Design of SteelStructures. The Canadian Standards Association, 1994 with CISC (CanadianInstitute of Steel Construction) handbook. CISC Handbook Example, Page 4_108.

Problem

Find the interaction ratio, beam and column resistance.

Given

E = 200000 MPa (STEEL).

International Design Codes Manual — 193

Page 204: International Codes v8i

Fy= 300 MPa   CSA G40.21-M

Simply supported beam/column has a 3.7 m span, Ky is 1.0, Kz 1.0, Lu = 3.7 m

factored axial load is 2000 kN and end moments of

200 kN*m and 300 kN*m in the strong axis and 100 kN*m at each end in theweak axis.

Steel section is W310X143.

Comparison

CAN/CSA-S16 Interaction Ratio Beam Resistance

(kN*m)

Column Resistance

(kN)

Weak Strong

REFERENCE 0.998 300 630 4200

STAAD.Pro 1.00 299 650 4222

****************************************************       *                                                 

*       *           STAAD.PRO                             

*       *           VERSION          BLD                  

*       *           PROPRIETARY PROGRAM OF                

*       *           RESEARCH ENGINEERS,  INTL.            

*       *           DATE=   

                              *       *           TIME=                                 

*       *                                                 

*       *      USER ID:                                   

*  

****************************************************       1. STAAD SPACE VERIFICATION CISC 1994 HANDBOOK EXAMPLE

PAGE 4-108

194— STAAD.Pro

Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01

Page 205: International Codes v8i

2. *3. * ( COMPRESSION + BIAXIAL BENDING )4. *5. UNIT METER KN6. JOINT COORDINATES7. 1 0 0 0; 2 0 3.7 08. *9. MEMBER INCIDENCES10. 1 1 211. *12. MEMBER PROPERTY CANADIAN13. 1 TABLE ST W310X14314. *15. CONSTANTS16. E STEEL ALL17. POISSON STEEL ALL18. *19. SUPPORTS20. 1 FIXED BUT MX MZ21. 2 FIXED BUT FY MX MY MZ22. *23. LOAD 1 FACTORED LOAD24. JOINT LOAD25. 2 FY -200026. 2 MZ 20027. 2 MX 10028. 1 MZ 30029. 1 MX 10030. *31. PERFORM ANALYSIS

P R O B L E M   S T A T I S T I C S-----------------------------------

NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS =     2/    1/     2

ORIGINAL/FINAL BAND-WIDTH=     1/     1/      6 DOFTOTAL PRIMARY LOAD CASES =    1, TOTAL DEGREES OF FREE-

DOM =      6SIZE OF STIFFNESS MATRIX =        1 DOUBLE  KILO-WORDSREQRD/AVAIL. DISK SPACE  =     12.0/  19641.2 MB33. PARAMETER34. CODE CANADIAN35. CMY 2 ALL36. CMZ 2 ALL37. CB 1 ALL38. TRACK 2 ALL39. FYLD 300000 ALL40. CHECK CODE ALL

STAAD.PRO CODE CHECKING - (CAN/CSA-S16-01)

****************************************** ALL UNITS ARE - KNS  MET  (UNLESS OTHERWISE NOTED) MEMBER     TABLE       RESULT/   CRITICAL COND/     RATIO/    LOADING/

FX            MY             MZ      LOCATION

International Design Codes Manual — 195

Page 206: International Codes v8i

 ======================================================================= *     1 ST   W310X143                 (CANADIAN SECTIONS)

FAIL     CSA-13.8.2A       1.000         1

2000.00 C       -100.00        300.00        0.00

MEMBER PROPERTIES (UNIT = CM)-----------------------------CROSS SECTION AREA =  1.82E+02   MEMBER LENGTH = 

3.70E+02IZ =  3.47E+04   SZ =  2.15E+03   PZ =  2.41E+03IY =  1.12E+04   SY =  7.28E+02   PY =  1.11E+03MATERIAL PROPERTIES (UNIT = MPA)--------------------------------FYLD = 300.0   FU = 345.0SECTION CAPACITIES (UNIT - KN,M)---------------------------------CR1 =  4.912E+03   CR2 =  4.222E+03CRZ =  4.737E+03   CTORFLX =  4.222E+03TENSILE CAPACITY     =  4.802E+03   COMPRESSIVE CAPACITY

=  4.912E+03FACTORED MOMENT RESISTANCE : MRY =  2.987E+02   MRZ = 

6.504E+02FACTORED SHEAR RESISTANCE  : VRY =  8.037E+02   VRZ = 

1.678E+03MISCELLANEOUS INFORMATION--------------------------NET SECTION FACTOR FOR TENSION =  1.000KL/RY =   47.077   KL/RZ =   26.802   ALLOWABLE KL/R = 

200.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) = 

3.700OMEGA-1 (Y-AXIS) = 0.40   OMEGA-1 (Z-AXIS) = 0.40  

OMEGA-2 = 1.00SHEAR FORCE (KNS) : Y AXIS =  1.351E+02   Z AXIS = 

5.405E+01SLENDERNESS RATIO OF WEB (H/W) =  1.98E+0141. STEEL MEMBER TAKE OFF ALLSTEEL TAKE-OFF--------------PROFILE               LENGTH(METE)      WEIGHT(KN  )IN STEEL TAKEOFF THE DENSITY OF STEEL IS ASSUMED FOR

MEMBERS WITH NO DENSITY.ST  W310X143                  3.70             5.171PRISMATIC STEEL               0.00             0.000

----------------TOTAL =          5.171

MEMBER      PROFILE           LENGTH        WEIGHT(METE)        (KN  )

1      ST  W310X143               3.70         5.171************ END OF DATA FROM INTERNAL STORAGE

************42. FINISH

196— STAAD.Pro

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Page 207: International Codes v8i

Verification Problem No. 4

Title

A slender, cantilever beam subjected to a uniform load

Type

Static analysis, 3D beam element.

Reference

CISC Example 1, page 5-91, Limit State Design, CSA-S16.1-94

Problem

A cantilever beam of length 4 meter is subjected to uniformly distributed load of 3KN/Meter in both major and minor axis. Axial compression of 8 KN is also appliedto the member. User defined steel section Sect_Class-4 from is assigned to themember.

Given

Design forces

8.0 KN (Compression)

6.0 KNm (Bending-Y)

6.0 KNm (Bending-Z)

6.0 KN (Shear-Y)

6.0 KN (Shear-Z)

Section Properties(Sect_Class-4):

Area = 2766 mm2

Depth of section, D = 150 mm

Thickness of web Tw = 7 mm

International Design Codes Manual — 197

Page 208: International Codes v8i

Width of flange Bf = 150 mm

Thickness of flange Tf = 6 mm

Moment of inertia about Z axis, Iz = 1086.96X104mm4

Moment of inertia about Y axis, Iy = 337.894X104mm4

Moment of inertia about X axis, Ix = 3.7378X104mm4

Warping constant, Cw = 1.752X1010mm6

Member Length L = 2 m, Unbraced length = 100mm.

Material

FYLD = 300 MPa

E = 2.05E+05 MPa

G = E/2.6 MPa

Solution

Slenderness Ratio

Effective Length factor along Local Y-Axis = KY = 1

Effective Length factor along Local Z-Axis = KZ = 1

Slenderness ratio about Z axis, L/Rz = 31.9

Slenderness ratio about Y axis, L/Ry = 57.22

Maximum Slenderness Ratio, L/Rmax = 57.22

Section Classification

Bf/Tf = 150*0.5/6 = 12.5 > 200/sqrt(Fy) = 11.54

Flange is Class 4.

d/Tw = (150-2.0*6)/7 = 19.714

(1100/sqrt(Fy))*(1-0.39*Cf/ϕ*Cy)=(1100/sqrt(300))*(1-0.39*8000/(0.9*2766*300)) = 63.24

Web is Class 1.

198— STAAD.Pro

Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01

Page 209: International Codes v8i

Overall section is Class 4 section.

Check against axial compression (Clause 13.3.3)

Effective width, Beff = 200*Tf/sqrt(300) = 69.24

Effective area, Aeff = 69.24*6*4+(150-2*6)*7 = 2627.76 mm4.

Effective yield stress, FYLDeff =40000/( 0.5*Bf/Tf)4 =256 MPa.

As per Clause 13.3.3(a),

Elastic critical buckling, Fe = π4*E/ L_Rmax4 = 617.956 MPa.

Non-dimensional slenderness ratio, λ = sqrt(FYLD/Fe) =0.697

Axial compressive resistance, Cr = ϕ*Aeff*FYLD*(1+0.697^(2*1.34))^(-1/1.34)= 557886.104 N.

As per Clause 13.3.3(b),

Elastic critical buckling, Fe = π4*E/ L_Rmax4 = 617.956 MPa.

Effective non-dimensional slenderness ratio, λeff = sqrt(FYLDeff/Fe) = 0.644

Axial compressive resistance, Cr = ϕ*Area*FYLDeff*(1+0.644^(2*1.34))^(-1/1.34) = 521726.94 N.

Axial compressive resistance Min(557886.104, 521726.94) = 521726.94 N.

Check against bending (Clause 13.5(c))

As the web of the section meets the requirement of Class 3 and flange exceedsClass 3 limit, flexural resistance should be calculated as per clause 13.5(c).iii.

Effective moment of inertia about Z axis,

Izeff =2*(2*69.24*63)/12 + 2*(2*69.24*6)*(150-6)*(150-6)/4 +(7*(150-2*6)3)/12 =10152591.12 mm4.

Effective section modulus about Z axis,

Szeff = 10152591.12*2/150 = 135367.88 mm3.

Effective moment of inertia about Y axis,

Iyeff =(2*6*(2*69.24)3)/12 +(0.5*(150-6)*73)/12 =2657648.856

International Design Codes Manual — 199

Page 210: International Codes v8i

mm4.

Effective section modulus about Y axis,

Syeff = 2657648.856/69.24 = 38383.144 mm3.

Major axis bending resistance if member is laterally supported,

Mrz1 = ϕ*Szeff*FYLD= 0.9*135367.88*300 =36549327.6 N-mm.

Minor axis bending resistance,

Mry = ϕ*Syeff*FYLD = 0.9*38383.144*300 = 10363448.88 N-mm.

If the member is laterally unsupported major axis bending resistance isdetermined by clause 13.6(b).

As the value of one of the end moments is 0.0, ω2 = 1.75.

Where, as per clause 13.6(a),

Mu =(1.75*3.14/2000)*sqrt(205000*337.894X104*78846.154*3.7378X104 +(3.14*205000/2000)4*337.894X104*1.752X10^10) =2.48X108

My = Sz*FYLD = (1086.96X104X2/150) *300 =43478400.

Since Mu > 0.65My,

Moment of resistance Mrz2 = 1.15*0.9*43478400*(1-0.28*43478400/2.48X108)=42791153.71 N-mm = 42.79 KN-m.

Mrz2 should not be more than Mrz1. Since, Mrz2 > Mrz1 in this example, Mrz2 =Mrz1.

Mrz2 = 36549327.6 N-mm = 36.549 KN-m

200— STAAD.Pro

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Page 211: International Codes v8i

Comparison

Hand Cal-culation

STAAD.ProResult

Comments

Axial compressiveresistance

521.73 KN 5.219X102KN

Negligible dif-ference.

Major axis bendingresistance

36.549KN-m

36.57 KN-m Negligible dif-ference.

Minor axis bendingresistance

10.363 KN-m

10.38 KN-m Negligible dif-ference.

*****************************************************

** STAAD.PRO V8I SELECTSERIES2

** VERSION 20.07.07.XX

** PROPRIETARY PROGRAM OF

** BENTLEY SYSTEMS, INC.

** DATE= AUG 17, 2010

** TIME= 17: 6:23

**

** USER ID: BENTLEY

*

****************************************************

1. STAAD SPACE VERIFICATION CISC 1994 HANDBOOK EXAMPLEPAGE 5-91INPUT FILE: S-16-01 VERIFICATION EXAMPLE.STD

2. START JOB INFORMATION3. ENGINEER DATE 16-FEB-104. END JOB INFORMATION5. * CISC EXAMPLE 1 PAGE 5-91, LIMIT STATES DESIGN,

CSA-S16.1-946. * SIMPLY SUPPORTED BEAM WITH UNIFORM LOAD7. * LIVE LOAD DEFLECTION OF L/3008. UNIT MMS KN9. JOINT COORDINATES10. 1 0 0 0; 2 2000 0 011. MEMBER INCIDENCES

International Design Codes Manual — 201

Page 212: International Codes v8i

12. 1 1 213. START USER TABLE14. TABLE 115. UNIT METER KN16. WIDE FLANGE17. SECT_CLASS-418. 0.002766 0.15 0.007 0.15 0.006 1.08696E-005

3.37894E-006 3.7378E-008 -19. 0.00105 0.001820. END21. UNIT METER KN22. DEFINE MATERIAL START23. ISOTROPIC MATERIAL124. E 2.05E+00825. POISSON 0.326. ISOTROPIC STEEL27. E 2.05E+00828. POISSON 0.329. DENSITY 76.819530. ALPHA 1.2E-00531. DAMP 0.0332. END DEFINE MATERIAL33. MEMBER PROPERTY34. 1 UPTABLE 1 SECT_CLASS-435. UNIT MMS KN36. CONSTANTS37. MATERIAL STEEL ALL38. SUPPORTS39. 1 FIXED40. UNIT METER KN41. LOAD 1 LC142. MEMBER LOAD43. 1 UNI GY -344. 1 UNI GZ -345. JOINT LOAD46. 2 FX -847. PERFORM ANALYSIS

P R O B L E M S T A T I S T I C S-----------------------------------

NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS = 2/1/ 1

SOLVER USED IS THE IN-CORE ADVANCED SOLVER

TOTAL PRIMARY LOAD CASES = 1, TOTAL DEGREES OF FREE-DOM = 6

48. LOAD LIST 149. PRINT MEMBER FORCES LIST 1VERIFICATION CISC 1994 HANDBOOK EXAMPLE PAGE 5-91

-- PAGE NO. 3

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MEMBER END FORCES STRUCTURE TYPE = SPACE-----------------ALL UNITS ARE -- KN METE (LOCAL )

MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSIONMOM-Y MOM-Z

1 1 1 8.00 6.00 6.00 0.00-6.00 6.00

2 -8.00 0.00 0.00 0.000.00 0.00

************** END OF LATEST ANALYSIS RESULT**************

50. PARAMETER 151. CODE CANADIAN52. CB 0 ALL53. TRACK 2 ALL54. FYLD 300000 ALL55. CHECK CODE ALL

STAAD.PRO CODE CHECKING - (CAN/CSA-S16-01 ) V2.0

********************************************

ALL UNITS ARE - KNS MET (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/LOADING/

FX MY MZLOCATION

=======================================================================

1 ST SECT_CLASS-4 (UPT)PASS CSA-13.8.3B 0.760

18.00 C -6.00 6.00

0.00

MEMBER PROPERTIES (UNIT = CM)-----------------------------

CROSS SECTION AREA = 2.77E+01 MEMBER LENGTH =2.00E+02

IZ = 1.09E+03 SZ = 1.45E+02 PZ = 1.63E+02IY = 3.38E+02 SY = 4.51E+01 PY = 6.92E+01

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IX = 3.74E+00 CW = 1.75E+04

EFFECTIVE MEMBER PROPERTIES FOR CLASS-4 SECTION(UNIT =CM)

----------------------------------------------------------

EFFECTIVE CROSS SECTION AREA = 2.63E+01EFFECTIVE IZ = 1.02E+03 EFFECTIVE SZ = 1.35E+02EFFECTIVE IY = 2.66E+02 EFFECTIVE SY = 3.85E+01

EFFECTIVE YILED STRESS = 256.0 MPA

COMPRESSIVE CAPACITIES FOR CLASS 4 SECTION(UNIT = MPA)------------------------------------------------------

BASED ON EFFECTIVE AREACR1 = 7.098E+02 CR2 = 5.582E+02 CRZ = 6.705E+02CTORFLX = 5.582E+02

BASED ON EFFECTIVE YIELD STRENGTHCR1 = 6.373E+02 CR2 = 5.219E+02 CRZ = 6.084E+02CTORFLX = 5.219E+02

MATERIAL PROPERTIES (UNIT = MPA)--------------------------------

FYLD = 300.0 FU = 345.0 E = 2.05E+05 G =7.88E+04

SECTION CAPACITIES (UNIT - KN,M)---------------------------------

CR1 = 6.373E+02 CR2 = 5.219E+02 SECTION CLASS 4CRZ = 6.084E+02 CTORFLX = 5.219E+02TENSILE CAPACITY = 7.300E+02 COMPRESSIVE CAPACITY

= 5.219E+02FACTORED MOMENT RESISTANCE : MRY = 1.038E+01 MRZ =

3.657E+01MU = 2.486E+02

FACTORED SHEAR RESISTANCE : VRY = 1.871E+02 VRZ =3.208E+02

MISCELLANEOUS INFORMATION--------------------------

NET SECTION FACTOR FOR TENSION = 1.000KL/RY = 57.222 KL/RZ = 31.904 ALLOWABLE KL/R =

200.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) =

2.000

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OMEGA-1 (Y-AXIS) = 1.00 OMEGA-1 (Z-AXIS) = 1.00OMEGA-2 = 1.75

SHEAR FORCE (KNS) : Y AXIS = 6.000E+00 Z AXIS =6.000E+00

SLENDERNESS RATIO OF WEB (H/W) = 1.97E+01

56. FINISH

*********** END OF THE STAAD.PRO RUN***********

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Canadian Codes - Design Per Canadian ColdFormed Steel Code S136-94

3C.1 General 

Provisions of CSA S136-94, including revisions dated May, 1995, have beenimplemented. The program allows design of single (non-composite) members intension, compression, bending, shear, as well as their combinations. For laterallysupported members in bending, the Initiation of Yielding method has been used.Cold work of forming strengthening effects have been included as an option.

3C.2 Cross-Sectional Properties

The user specifies the geometry of the cross-section by selecting one of the sectionshape designations from the Gross Section Property Tables published in the "Cold-Formed Steel Design Manual", AISI, 1996 Edition.

The Tables are currently available for the following shapes:

l Channel with Lips

l Channel without Lips

l Angle with Lips

l Angle without Lips

l Z with Lips

l Z without Lips

l Hat

Shape selection may be done using the member property pages of the graphicaluser interface (GUI) or by specifying the section designation symbol in the inputfile.

The properties listed in the tables are gross section properties. STAAD.Pro usesunreduced section properties in the structure analysis stage. Both unreduced andeffective section properties are used in the design stage, as applicable.

3C.3 Design Procedure

The following two design modes are available:

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a. Code Checking

The program compares the resistance of members with the applied loadeffects, in accordance with CSA 136. Code checking is carried out forlocations specified via the SECTION command or the BEAM parameter. Theresults are presented in a form of a PASS/FAIL identifier and a RATIO of loadeffect to resistance for each member checked. You may choose the degree ofdetail in the output data by setting the TRACK parameter.

Refer to Section 2.5 of the Technical Reference Manual for generalinformation on Code Checking. Refer to Section 5.48.2 of the TechnicalReference Manual for details the specification of the Code Checkingcommand.

b. Member Selection

You may request that the program search the cold formed steel shapesdatabase (AISI standard sections) for alternative members that pass the codecheck and meet the least weight criterion. In addition, a minimum and/ormaximum acceptable depth of the member may be specified. The programwill then evaluate all database sections of the type initially specified (i.e.,channel, angle, etc.) and, if a suitable replacement is found, present designresults for that section. If no section satisfying the depth restrictions orlighter than the initial one can be found, the program leaves the memberunchanged, regardless of whether it passes the code check or not.

Refer to Section 2.6 of the Technical Reference Manual for generalinformation on Member Selection. Refer to Section 5.48.3 of the TechnicalReference Manual for details the specification of the Member Selectioncommand.

The program calculates effective section properties in accordance with Clauses5.6.2.1 through 3 and 5.6.2.6 through 8. Cross-sectional properties and overallslenderness of members are checked for compliance with

l Clause 5.3, Maximum Effective Slenderness Ratio for members inCompression

l Clause 5.4, Maximum Flat Width Ratios for Elements in Compression

l Clause 5.5, Maximum Section Depths.

The program will check member strength in accordance with Clause 6 of theStandard as follows:

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l Resistance factors listed in Clauses 6.2 (a), (b), and (e) are used, asapplicable.

l Members in tension - Resistance is calculated in accordance with Clauses6.3.1 and 6.3.2.

l Members in bending and shear

Resistance calculations are based on Clauses:

l 6.4.1 General,

l 6.4.2 and 6.4.2.1 Laterally Supported Members, compressive limit stressbased on Initiation of Yielding,

l 6.4.3 Laterally Unsupported Members,

l 6.4.4 Channels and Z-Shaped Members with Unstiffened Flanges - additionallimitations,

l 6.4.5 Shear in Webs,

l 6.4.6 Combined Bending and Shear in Webs.

l Members in compression

Resistance calculations are based on Clauses:

o 6.6.1.1, 6.6.1.2 (a) and (d), and 6.6.1.3 General,

o 6.6.2 Sections Not Subject to Torsional-Flexural Buckling,

o 6.6.3 Singly Symmetric Sections,

o 6.6.4 Point-Symmetric Sections,

o 6.6.5 Cylindrical Tubular Sections.

l Members in compression and bending

Resistance calculations are based on Clause 6.7.1, Singly and DoublySymmetric Sections. Input for the coefficients of uniform bending must beprovided.

3C.4 Design Parameters

The following table contains the input parameters for specifying values of designvariables and selection of design options.

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Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified S136.

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM 1.0 When this parameter is set to 1.0(default), the adequacy of themember is determined by checkinga total of 13 equally spacedlocations along the length of themember. If the BEAM value is 0.0,the 13 location check is notconducted, and instead, checkingis done only at the locationsspecified by the SECTIONcommand (See STAAD manual fordetails). If neither the BEAMparameter nor any SECTIONcommand is specified, STAAD willterminate the run and ask the userto provide one of those 2commands. This rule is notenforced for TRUSS members.

CMZ 1.0 Coefficient of equivalent uniformbending W

z. See CSA 136, 6.7.2.

Used for Combined axial load andbending design. Values range from0.4 to 1.0.

Table 3C.1 - Canadian Cold Formed Steel Design Parameters

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ParameterName

DefaultValue

Description

CMY 0.0 Coefficient of equivalent uniformbending W

y. See CSA 136, 6.7.2.

Used for Combined axial load andbending design. Values range from0.4 to 1.0.

CWY 0 Specifies whether the cold work offorming strengthening effectshould be included in resistancecomputation. See CSA 136, 5.2.

0. effect should not be included

1. effect should be included

DMAX 1000.0 Maximum depth permissible for thesection during member selection.This value must be provided in thecurrent units.

DMIN 0.0 Minimum depth required for thesection during member selection.This value must be provided in thecurrent units.

FLX 1 Specifies whether torsional-flexural buckling restraint isprovided or is not necessary forthe member. See CSA 136, 6.6.2

0. Section subject to torsionalflexural buckling andrestraint not provided

1. restraint provided or unnec-essary

FU 450 MPa Ultimate tensile strength of steel incurrent units.

FYLD 350 MPa Yield strength of steel in currentunits.

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ParameterName

DefaultValue

Description

KT 1.0 Effective length factor for torsionalbuckling. It is a fraction and isunit-less. Values can range from0.01 (for a column completelyprevented from torsional buckling)to any user specified large value. Itis used to compute the KL/R ratiofor twisting for determining thecapacity in axial compression.

KY 1.0 Effective length factor for overallcolumn buckling about the local Y-axis. It is a fraction and is unit-less.Values can range from 0.01 (for acolumn completely prevented frombuckling) to any user specifiedlarge value. It is used to computethe KL/R ratio for determining thecapacity in axial compression.

KZ 1.0 Effective length factor for overallcolumn buckling in the local Z-axis.It is a fraction and is unit-less.Values can range from 0.01 (for acolumn completely prevented frombuckling) to any user specifiedlarge value. It is used to computethe KL/R ratio for determining thecapacity in axial compression.

LT Memberlength

Unbraced length for twisting. It isinput in the current units of length.Values can range from 0.01 (for acolumn completely prevented fromtorsional buckling) to any userspecified large value. It is used tocompute the KL/R ratio for twistingfor determining the capacity inaxial compression.

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ParameterName

DefaultValue

Description

LY Memberlength

Effective length for overall columnbuckling in the local Y-axis. It isinput in the current units of length.Values can range from 0.01 (for acolumn completely prevented frombuckling) to any user specifiedlarge value. It is used to computethe KL/R ratio for determining thecapacity in axial compression.

LZ Memberlength

Effective length for overall columnbuckling in the local Z-axis. It isinput in the current units of length.Values can range from 0.01 (for acolumn completely prevented frombuckling) to any user specifiedlarge value. It is used to computethe KL/R ratio for determining thecapacity in axial compression.

NSF 1.0 Net section factor for tensionmembers, See CSA 136, 6.3.1.

STIFF Memberlength

Spacing in the longitudinaldirection of shear stiffeners forstiffened flat webs. It is input in thecurrent units of length. See sectionCSA 136, 6.4.5

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ParameterName

DefaultValue

Description

TRACK 0 This parameter is used to controlthe level of detail in which thedesign output is reported in theoutput file. The allowable valuesare:

0. Prints only the membernumber, section name, ratio,and PASS/FAIL status.

1. Prints the design summary inaddition to that printed byTRACK 1

2. Prints member and materialproperties in addition to thatprinted by TRACK 2.

TSA 1 Specifies whether bearing andintermediate transverse stiffenerssatisfy the requirements of CSA136, 6.5. If true, the program usesthe more liberal set of interactionequations in 6.4.6.

0. stiffeners do not comply with6.5

1. stiffeners comply with 6.5

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Canadian Codes - Wood Design Per CSA Stand-ard CAN/CSA-086-01

3D.1 General  Comments

The Canadian Wood Design facility in STAAD is based on CSA086-01. A timbersection library consisting of Sawn and Glulam timber is available for memberproperty specification.

The design philosophy of  this specification is based on the concept of limit statedesign. Structures are designed and proportioned taking into consideration thelimit states at which they would become unfit for their intended use. Two majorcategories of limit-state are recognized - ultimate and serviceability. The primaryconsiderations in ultimate limit state design are strength and stability, while that inserviceability is deflection. Appropriate load and resistance factors are used so thata uniform reliability is achieved for the entire structure under various loadingconditions and at the same time the chances of limits being surpassed areacceptably remote.

In the STAAD implementation, the code checking portion of the program checkswhether code requirements for each selected section are met and identifies thegoverning criteria.

The following sections describe the salient features of the STAAD implementationof CSA086-01. A detailed description of the design process along with itsunderlying concepts and assumptions is available in the specification document.

3D.2 Analysis Methodology

Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loading specificationsand using appropriate load factors to create necessary loading situations.

3D.3 Member Property Specifications

For specification of member properties, for Sawn timber the timber section libraryavailable in STAAD may be used. The next section describes the syntax ofcommands used to assign properties from the built-in timber table.

For Glulam timber, member properties can be specified using the YD (depth) andZD (width) specifications and selecting Combination and Species specifications

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from the built-in table. The assignment is done with the help of the PRISMATICoption (Refer to Section 5.20 of the Technical Reference Manual)

3D.4 Built-in Timber Section Library

The following information is provided for use when the built-in timber tables areto be referenced for member property specification. These properties are stored ina database file. If called for, the properties are also used for member design.

Following are the description of the different types of species combinationavailable:

Douglas Fir-Larch

The following example illustrates the specification of Douglas Fir-Larch speciescombination.

100 TO 150 TABLE ST DFL_SELSTR_2X2_BM

Hem-Fir

Designation of Hem-Fir species combination in STAAD is as follows.

100 TO 150 TABLE ST HEM-FIR_SELSTR_2X10_BM

Northern Species

Designation of Northern species combination in STAAD is as follows.

100 TO 150 TABLE ST NORTHERN_SELSTR_3X12_BM

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Spruce-Pine-Fir

Designation of Spruce-Pine-Fir species combination in STAAD is as follows.

100 TO 150 TABLE ST SPF_SELSTR_3X8_BM

Glu Laminated timber

Designation of Glu-lam timber in STAAD involves defining the material, specifyingthe dimensions, and associating the material with the member through theCONSTANTS command.

UNIT CMKN

DEFINEMATERIAL START

ISOTROPIC GLT_D.FIR-L-24F-EX

E 51611.7

POISSON 0.15

DENSITY 2.5E-005

ALPHA 1.2E-011

END DEFINEMATERIAL

MEMBER PROPERTYTIMBER CANADIAN

1 PRIS YD 12 ZD 6

CONSTANTS

MATERIAL GLT_D.FIR-L-24F-EX MEMB 1

Sample input file to demonstrate usage of Canadian timber

STAAD PLANE EXAMPLE FOR DIMENSIONAL LUMBER

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UNIT FEET POUND

JOINT COORDINATES

1 0 0 0; 2 6 0 0; 3 12 0 0; 4 18 0 0;

5 24 0 0; 6 6 3 0; 7 12 6 0; 8 18 3 0;

MEMBER INCIDENCES

1 1 2; 2 2 3; 3 3 4; 4 4 5; 5 1 6; 6 6 7; 7 7 8; 8 8 5;

9 2 6; 10 3 7; 11 4 8; 12 6 3; 13 3 8;

UNIT FEET POUND

DEFINEMATERIAL START

ISOTROPIC SPF_SELSTR_4X10_BM

E 1224

POISSON 0.15

DENSITY 25

ALPHA 5.5E-006

END DEFINEMATERIAL

MEMBER PROPERTYTIM CAN

1 TO 4 9 TO 11 TABLE ST SPF_SELSTR_4X10_BM

5 TO 8 12 13 TABLE ST SPF_SELSTR_4X10_BM

CONSTANTS

MATERIAL SPF_SELSTR_4X10_BMMEMB 1 TO 4 9 TO 11

MATERIAL SPF_SELSTR_4X10_BMMEMB 5 TO 8 12 13

PRINT MEMBER PROPERTIES

FINISH

3D.5 Member Resistance

The member resistances are calculated in STAAD according to the proceduresoutlined in section 5 (for sawn lumber) and 6 (for Glulam) of CSA086-01.

These depend on several adjustment factors as follows:

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a. KD = Load duration factor (Clause 4.3.2.2-CSA086-01, Table 4.3.2.2)

b. KH = System factor (Clause 5.4.4 and 6.4.3 and Table 5.4.4 -CSA086-01)

c. K_T = Treatment factor (Clause 5.4.3 and 6.4.4 -CSA086-01)

d. KSB = Service condition factor applicable to Bending at extreme fibre (Table5.4.2 and 6.4.2 -CSA086-01)

e. KSV = Service condition factor applicable to longitudinal shear (Table 5.4.2and 6.4.2 CSA086-01)

f. KSC = Service condition factor applicable to Compression parallel to the grain(Table 5.4.2 and 6.4.2 CSA086-01)

g. K_SCP = Service condition factor applicable to Compression perpendicular tothe grain (Table 5.4.2 and 6.4.2 CSA086-01)

h. KSE = Service condition factor applicable to modulus of elasticity (Table 5.4.2and 6.4.2  CSA086-01)

i. KST = Service condition factor applicable to tension parallel to the grain(Table 5.4.2 and 6.4.2 CSA086-01)

j. KZB = Size factor applicable to bending (Clause 5.4.5 and Table 5.4.5 -CSA086-01)

k. KZV = size factor applicable to shear(Clause 5.4.5 and Table 5.4.5 -CSA086-01)

l. KZT = size factor applicable to tension parallel to grain (Clause 5.4.5 andTable 5.4.5 -CSA086-01)

m. KZCP = size factor applicable to compression perpendicular to grain (Clause5.4.5 and Table 5.4.5 -CSA086-01)

n. K_ZC = size factor applicable to compression parallel to grain (Clause 5.4.5and Table 5.4.5 -CSA086-01)

o. CHIX = Curvature factor (Clause 6.5.6.5.2-CSA086-01)

p. CV = shear load coefficient (Table 6.5.7.4A- CSA086-01)

q. KN = Notch factor(Clause 5.5.5.4-CSA086-01)

All of these factors must be specified as input according to the classification oftimber and stress grade.

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Explained here is the procedure adopted in STAAD for calculating the memberresistances.

Axial Tension

i. For Sawn timber 

The criterion governing the capacity of tension members is based on onelimit state. The limit state involves fracture at the section with the minimumeffective net area. The net  section area may be specified by the user throughthe use of the parameter NSF (see Table 3B.1). STAAD calculates the tensioncapacity of a member based on this limit state per Clause 5.5.9 of CSA086-01.

ii. For Glulam timber 

The design of glulam tension members differs from sawn timber since CSA086-01 assigns different specified strength for gross and net section. Thespecified strength at net section is slightly higher than the strength of thegross section. Therefore, Glulam tension members are designed based ontwo limit states. The first one is the limit state of yielding in the gross section.The second limit state involves fracture at the section with the minimumeffective net area. The net-section area may be specified by the user throughthe use of the parameter  NSF (see Table 3B.1). STAAD calculates the tensioncapacity of a member based on these two limits states per Clause.6.5.11 ofCSA086-01.

Axial Compression

The compressive resistance of columns is determined based on Clause.5.5.6 andClause.6.5.8.4 of CSA086-01. The equations presented in this section of the codeassume that the compressive resistance is a function of the compressive strengthof the gross section (Gross section Area times the Yield Strength) as well as theslenderness factor (Kc). The effective length for the calculation of compressionresistance may be provided through the use of the parameters KX, KY, KZ, LX, LYand LZ (see Table 3B.1).

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Bending

The bending resistance of Sawn members are determined based on Clause 5.5.4 ofCSA086-01 and for glulam members are determined based on Clause 6.5.6.5 ofCSA086-01. The allowable stress in bending is multiplied by Lateral stability factor,KL to take in account whether lateral support is provided at points of bearing toprevent lateral displacement and rotation

Axial compression and bending

The member strength for sections subjected to axial compression and uni-axial orbiaxial bending is obtained through the use of interaction equations. Clause 5.5.10and 6.5.12 of the code provides the equations for this purpose. If the summation ofthe left hand side of these equations exceeds 1.0 or the allowable value providedusing the RATIO parameter (see Table 3B.1), the member is considered to haveFAILed under the loading condition.

Axial tension and bending

The member strength for sections subjected to axial tension and uniaxial or biaxialbending is obtained through the use of interaction equations. Clause 5.5.10 and6.5.12 of the code provides the equations for this purpose. If the summation of theleft hand side of these equations exceeds 1.0 or the allowable value provided usingthe RATIO parameter (see Table 3B.1), the member is considered to have FAILedunder the loading condition.

Shear

The shear resistance of the cross section is determined using the equations ofClause 5.5.5 and 6.5.7.2 of the code. Once this is obtained, the ratio of the shearforce acting on the cross section to the shear resistance of the section is calculated.If any of the ratios (for both local Y & Z axes) exceed 1.0 or the allowable valueprovided using the RATIO parameter (see Table 3B.1), the section is considered tohave failed under shear.

3D.6 Design Parameters

The design parameters outlined in Table below may be used to control the designprocedure. These parameters communicate design decisions from the engineer to

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the program and thus allows the engineer to control the design process to suit anapplication's specific needs.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements, some or all of these parameter values may be changed to exactlymodel the physical structure.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified asTIMBER CANADIAN.

Design Code to follow. See section5.51.1 of the Technical ReferenceManual.

CHIX 1.0 Curvature Factor for Compression[Clause 6.5.6.5.2]

CV 1.0 Shear Load Coefficient [Table6.5.7.4A]

KD 1.0 Load Duration Factor[Clause.4.3.2, Table 4.3.2]

KH 1.0 System Factor [Clause 5.4.4/6.4.3,Table 5.4.4]

KN 1.0 Notch Factor [Clause 5.4.7.2.2]

KSB 1.0 Service Condition Factor forBending at Extreme Fibre

Applicable for bending at extremefibre [Table 5.4.2 and 6.4.2]

Table 3D.1 - Canadian Timber Design Parameters

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ParameterName

DefaultValue

Description

KSC 1.0 Service Condition Factor forCompression,

Applicable for compression parallelto grain [Table 5.4.2 and 6.4.2]

KSE 1.0 Service Condition Factor forModulus of Elasticity,

Applicable for modulus of elasticity[Table 5.4.2 and 6.4.2]

KST 1.0 Service Condition Factor forTension,

Applicable for tension parallel tograin [Table 5.4.2 and 6.4.2]

KSV 1.0 Service Condition Factor for Shear,

Applicable for longitudinal shear[Table 5.4.2 and 6.4.2]

KX 1.0 K value for flexural torsionalbuckling

KY 1.0 K value in local Y-axis, usuallyminor axis

KZ 1.0 K value in local Z-axis, usuallymajor axis

KZB 1.0 Size Factor for Bending,

Applicable for bending[Clause.5.4.5 and Table 5.4.5]

KZCP 1.0 Size Factor for Compression,

Applicable for compressionperpendicular to grain [Clause.5.4.5 and Table 5.4.5]

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ParameterName

DefaultValue

Description

KZT 1.0 Size Factor for Tension,

Applicable for tension parallel tograin

[Clause 5.4.5 and Table 5.4.5]

KZV 1.0 Size Factor for Shear [Clause 5.4.5and Table 5.4.5]

K_SCP 1.0 Service Condition Factor forCompression,

Applicable for compressionperpendicular to grain [Clause5.4.2 and Table 6.4.2]

K_T 1.0 Treatment Factor [Clause5.4.3/6.4.4]              

K_ZC 1.0 Size Factor for Compression,

Applicable for compression parallelto grain [Clause 5.4.5 and Table5.4.5]

LX Memberlength

Length for flexural torsionalbuckling

LY Memberlength

Length in local Y axis forslenderness value KL/r

LZ Memberlength

Length in local Z axis forslenderness value KL/r

NSF 1.0 Net section factor for tensionmembers

RATIO 1.0 Permissible Ratio of Actual toAllowable Value

224— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 235: International Codes v8i

3D.7 Code Checking

The purpose of code checking is to check whether the provided section propertiesof the members are adequate. The adequacy is checked as per the CSA086-01requirements.

Code checking is done using forces and moments at specified sections of themembers. The code checking output labels the members as PASSed or FAILed. Inaddition, the critical condition, governing load case, location (distance from thestart joint) and magnitudes of the governing forces and moments are also printed.

Refer to Section 4.4 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.51.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

PARAMETER

CODE TIMBER CAN

KD 0.99 ALL

KH 0.99 ALL

K_T 0.99 ALL

KSB 0.99 ALL

KSV 0.99 ALL

KSC 0.99 ALL

KSE 0.99 ALL

KST 0.99 ALL

KZB 0.99 ALL

KZV 0.99 ALL

KZT 0.99 ALL

KZCP 0.99 ALL

K_ZC 0.99 ALL

CV 0.99 ALL

KN 0.99 ALL

K_SCP 0.99 ALL

CHIX 0.99 ALL

International Design Codes Manual — 225

Page 236: International Codes v8i

RATIO 0.99 ALL

CHECK CODE ALL

FINISH

3D.8 Member Selection

Member selection based CSA086-2001 is not available.

3D.9 Tabulated Results of Timber Design

Results of code checking and member selection are presented in a tabular format.The term CRITICAL COND refers to the section of the CSA086-01 specification,which governed the design.

Pu = Actual Load in Compression

Tu = Actual Load in Tension

Muy = Ultimate moment in y direction

Muz = Ultimate moment in z direction

V = Ultimate shear force

SLENDERNESS_Y = Actual Slenderness ratio in y direction

SLENDERNESS_Z = Actual Slenderness ratio in z direction

PY = Factored Compressive capacity in y direction

PZ = Factored Compressive capacity in z direction

T = Factored tensile capacity

MY = Factored moment of resistance in y direction

MZ = Factored moment of resistance in z direction

V = Factored shear resistance

SLENDERNESS = Allowable slenderness ratio

3D.10 Verification Problems

In the next few pages are included 6 verification examples for reference purposes.

226— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 237: International Codes v8i

Verification Problem No. 1

Reference

Example 4, page 116, Canadian Wood Design Manual, 2001

Problem

To determine the Canadian Glulam section column in axial compression, withdesign per Canadian wood design code (CSA:086-01 . Column is effectively pinnedat both ends and braced at mid-height in all direction.

Given

Length = 9000 mm

Comparison

Source Design Strength (kN)

Reference 295

STAAD.Pro 293.793

Difference 0.43% (Negligible)

Table 3D.2 - CAN/CSA-086-01 Verification Prob-lem 1

Input File

This file is included in as …\STAAD\EXAMP\CAN\CANADA_GLULAMCOLUMN.STD.

STAAD PLANE EXAMPLE FOR GLULAMDESIGN INPUT FILE:GLULAMCOLUMN.STD

START JOB INFORMATION

ENGINEER DATE 10-JUN-05

END JOB INFORMATION

INPUT WIDTH 79

International Design Codes Manual — 227

Page 238: International Codes v8i

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 9 0;

MEMBER INCIDENCES

1 1 2;

UNIT INCHES KIP

DEFINEMATERIAL START

ISOTROPIC GLT_SPRUCE-PINE-12C-E

E 9.7

POISSON 0.15

DENSITY 1.44676E-005

ALPHA 5.5E-006

END DEFINEMATERIAL

UNIT FEET POUND

MEMBER PROPERTYTIMBER CANADIAN

1 PRIS YD 0.748031 ZD 0.574147

UNIT INCHES KIP

CONSTANTS

MATERIAL GLT_SPRUCE-PINE-12C-EMEMB 1

SUPPORTS

1 PINNED

UNIT METER KN

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1 

JOINT LOAD

2 FY -214

PERFORMANALYSIS

PARAMETER

CODE TIMBER CANADIAN

KY 0.5 ALL

KZ 0.5 ALL

228— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 239: International Codes v8i

CHECK CODE ALL

FINISH

Output for Member Design

STAAD.Pro CODE CHECKING - (S086)***********************

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 175.00X228.00 CANADIAN GLULAM GRADE:GLT_SPRUCE-PINE-12C-EPASS CL.5.5.10/6.5 0.728 1

214.00 C 0.00 0.00 0.0000|--------------------------------------------------------------------

------|| LEZ = 4500.000 LEY = 4500.000 LUZ = 9000.000 LUY =

9000.000mm ||

|| KD = 1.000 KH = 1.000 KT = 1.000 KSB = 1.000 KSV =

1.000 || KSC = 1.000 K_SCP = 1.000 KSE = 1.000 KST = 1.000 KZB =

1.000 || KZV = 1.000 KZT = 1.000 KZCP = 1.000 K_ZC = 1.000 CHIX =

1.000 || CV = 1.000 KN = 1.000

||

|| ACTUAL LOADS : (KN-m)

|| Pu = 214.000

|| Tu = 0.000

|| Muy = 0.000

|| Muz = 0.000

|| V = 0.000

|| SLENDERNESS_Y = 19.737

|| SLENDERNESS_Z = 25.714

|

International Design Codes Manual — 229

Page 240: International Codes v8i

| ALLOWABLE CAPACITIES OF THE SECTION: (KN-m)|

| PY = 413.943|

| PZ = 293.793|

| T = 0.000|

| MY = 0.000|

| MZ = 0.000|

| V = 0.000|

| SLENDERNESS = 50.000|

|--------------------------------------------------------------------------|

Verification Problem: 2

Objective:- To determine the bending capacity of a Canadian Glulam sectionsingle span floor beam. The compression edge assumed fully supported.      

Design Code:- Canadian wood design code (CSA:086-01)

Reference: - Example 2, page 59, Canadian Wood Design Manual, 2001    

Given:- Length =7500mm, Beam Spacing = 5000mm, Standard load condition,Dry service condition, Untreated            

Comparison: -

Solution Design Strengthin bending (kN-m)

DesignStrength inshear (kN)

Theory 208 101STAAD 208.323 100.776Difference 0.155% -0.221 %

Input: -

STAAD PLANE EXAMPLE FOR GLULAMDESIGN INPUT FILE:GLULAMBEAM.STD

START JOB INFORMATION

ENGINEER DATE 10-JUN-05

230— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 241: International Codes v8i

END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 7.5 0 0

MEMBER INCIDENCES

1 1 2

UNIT INCHES KIP

DEFINEMATERIAL START

ISOTROPIC GLT_SPRUCE-PINE-12C-E

E 9.7

POISSON 0.15

DENSITY 1.44676E-005

ALPHA 5.5E-006

ISOTROPIC GLT_D.FIR-L-20F-E

E 12.4

POISSON 0.15

DENSITY 1.44676E-005

ALPHA 5.5E-006

ISOTROPIC CONCRETE

E 3150

POISSON 0.17

DENSITY 8.68E-005

ALPHA 5.5E-006

DAMP 0.05

END DEFINEMATERIAL

UNIT FEET POUND

MEMBER PROPERTYTIMBER CANADIAN

1 PRIS YD 2.11942 ZD 0.426508

UNIT INCHES KIP

International Design Codes Manual — 231

Page 242: International Codes v8i

CONSTANTS

MATERIAL GLT_D.FIR-L-20F-EMEMB 1

SUPPORTS

1 2 PINNED

UNIT METER KN

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1 

MEMBER LOAD

1 UNIGY -27.1

PERFORMANALYSIS

PARAMETER

CODE TIMBER CANADIAN

CHECK CODE ALL

FINISH

Relevant portion of Output:

STAAD.Pro CODE CHECKING - (S086)

***********************                         

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)   

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/                     

FX MY MZ LOCATION                                                       

======================================================================= 

1 130.00X646.00 CANADIAN GLULAM GRADE:GLT_D.FIR-L-20F-E

FAIL CL.5.5.5/6.5. 1.008 1                                            

0.00 T 0.00 0.00 0.0000                                               

|--------------------------------------------------------------------------|  

| LEZ = 7500.000 LEY = 7500.000 LUZ = 7500.000 LUY = 7500.000mm |             

| |                                                                           

232— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 243: International Codes v8i

| KD = 1.000 KH = 1.000 KT = 1.000 KSB = 1.000 KSV = 1.000 |                  

| KSC = 1.000 K_SCP = 1.000 KSE = 1.000 KST = 1.000 KZB = 1.000 |             

| KZV = 1.000 KZT = 1.000 KZCP = 1.000 K_ZC = 1.000 CHIX = 1.000 |            

| CV = 1.000 KN = 1.000 |                                                     

| |                                                                           

| ACTUAL LOADS : (KN-m) |                                                     

| Pu = 0.000 |                                                                

| Tu = 0.000 |                                                                

| Muy = 0.000 |                                                               

| Muz = 0.000 |                                                               

| V = 101.625 |                                                               

| SLENDERNESS_Y = 16.932 |                                                    

| SLENDERNESS_Z = 1.529 |                                                     

| ALLOWABLE CAPACITIES OF THE SECTION: (KN-m) |                               

| PY = 0.000 |                                                                

| PZ = 0.000 |                                                                

| T = 0.000 |                                                                 

| MY = 41.923 |                                                               

| MZ = 208.323 |                                                              

| V = 100.776 |                                                               

| SLENDERNESS = 50.000 |                                                      

|--------------------------------------------------------------------------|  

46. FINISH    

International Design Codes Manual — 233

Page 244: International Codes v8i

Verification Problem: 3

Objective:- To determine the capacity of a Canadian Glulam section in axialtension.

Design Code: - Canadian wood design code (CSA:086-01)

Reference:- Example 3, page 158, Canadian Wood Design Manual, 2001    

Given:- Dry service condition, Untreated            

Comparison: -

Solution DesignStrengthin Tension(kN)

Theory 257STAAD 256.636Difference -0.141 %

Input: -

STAAD PLANE EXAMPLE FOR GLULAMDESIGN INPUT FILE:GLULAMTENSION.STD

START JOB INFORMATION

ENGINEER DATE 10-JUN-05

END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 9 0

MEMBER INCIDENCES

1 1 2

UNIT INCHES KIP

DEFINEMATERIAL START

ISOTROPIC GLT_SPRUCE-PINE-14T-E

234— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 245: International Codes v8i

E 10.7

POISSON 0.15

DENSITY 1.44676E-005

ALPHA 5.5E-006

ISOTROPIC CONCRETE

E 3150

POISSON 0.17

DENSITY 8.68E-005

ALPHA 5.5E-006

DAMP 0.05

END DEFINEMATERIAL

UNIT FEET POUND

MEMBER PROPERTYTIMBER CANADIAN

1 PRIS YD 0.872702 ZD 0.262467

UNIT INCHES KIP

CONSTANTS

MATERIAL GLT_SPRUCE-PINE-14T-EMEMB 1

SUPPORTS

1 PINNED

UNIT METER KN

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1 

JOINT LOAD

2 FY 250

PERFORMANALYSIS PRINT STATICS CHECK

PARAMETER

CODE TIMBER CANADIAN

KY 0.5 ALL

KZ 0.5 ALL

CHECK CODE ALL

FINISH

International Design Codes Manual — 235

Page 246: International Codes v8i

Relevant portion of Output:

STAAD.Pro CODE CHECKING - (S086)                         

***********************                         

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)   

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/                     

FX MY MZ LOCATION                                                       

======================================================================= 

1 80.00X266.00 CANADIAN GLULAM GRADE:GLT_SPRUCE-PINE-14T-E

PASS CL.5.5.10/6.5 0.974 1                                            

250.00 T 0.00 0.00 0.0000                                             

|--------------------------------------------------------------------------|  

| LEZ = 4500.000 LEY = 4500.000 LUZ = 9000.000 LUY = 9000.000mm |             

| |                                                                           

| KD = 1.000 KH = 1.000 KT = 1.000 KSB = 1.000 KSV = 1.000 |                  

| KSC = 1.000 K_SCP = 1.000 KSE = 1.000 KST = 1.000 KZB = 1.000 |             

| KZV = 1.000 KZT = 1.000 KZCP = 1.000 K_ZC = 1.000 CHIX = 1.000 |            

| CV = 1.000 KN = 1.000 |                                                     

| |                                                                           

| ACTUAL LOADS : (KN-m) |                                                     

| Pu = 0.000 |                                                                

| Tu = -250.000 |                                                             

| Muy = 0.000 |                                                               

| Muz = 0.000 |                                                               

| V = 0.000 |                                                                 

| ALLOWABLE CAPACITIES OF THE SECTION: (KN-m) |                               

| PY = 0.000 |                                                                

236— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 247: International Codes v8i

| PZ = 0.000 |                                                                

| T = 256.636 |                                                               

| MY = 0.000 |                                                                

| MZ = 0.000 |                                                                

| V = 0.000 |                                                                 

|--------------------------------------------------------------------------|  

Verification Problem: 4

Objective:- To determine the Canadian Sawn section column in axialcompression. Column is effectively pinned at both ends.      

Design Code: - Canadian wood design code (CSA:086-01)

Reference:- Example 2, page 113, Canadian Wood Design Manual, 2001    

Given: - Unbraced Length = 5000mm           

Comparison: -

Solution DesignStrength(kN)

Theory 130STAAD 129.223Difference -0.597 %

Input: -

STAAD PLANE EXAMPLE FOR DIMENSIONAL LUMBER INPUT FILE:SAWN_ LUMBER_ COLUMN.STD

START JOB INFORMATION

ENGINEER DATE 08-JUN-05

END JOB INFORMATION

UNIT FEET POUND

JOINT COORDINATES

1 0 0 0; 2 0 16.4042 0

International Design Codes Manual — 237

Page 248: International Codes v8i

MEMBER INCIDENCES

1 1 2

DEFINEMATERIAL START

ISOTROPIC DFL_NO2_8X8_POST

E 1.368E+006

POISSON 0.15

DENSITY 25

ALPHA 5.5E-006

END DEFINEMATERIAL

UNIT METER KN

CONSTANTS

MATERIAL DFL_NO2_8X8_POST MEMB 1

UNIT FEET POUND

MEMBER PROPERTYTIMBER CANADIAN

1 TABLE ST DFL_NO2_8X8_POST

SUPPORTS

1 PINNED

UNIT METER KN

LOAD 1 DEAD+LIVE LOAD

JOINT LOAD

2 FY -114

PERFORMANALYSIS PRINT STATICS CHECK

PARAMETER

CODE TIMBER CANADIAN

KSC 0.91 ALL

K_ZC 1.05 ALL

CHECK CODE

FINISH

Relevant portion of Output:

STAAD.Pro CODE CHECKING - (S086)                                 

238— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 249: International Codes v8i

***********************                         

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)   

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/                     

FX MY MZ LOCATION                                                       

======================================================================= 

1 ST DFL_NO2_8X8_POST

PASS CL.5.5.10/6.5.12 0.882 1                                            

114.00 C 0.00 0.00 0.0000                                             

|--------------------------------------------------------------------------|  

| LEZ = 5000.000 LEY = 5000.000 LUZ = 5000.000 LUY = 5000.000mm |             

| |                                                                           

| KD = 1.000 KH = 1.000 KT = 1.000 KSB = 1.000 KSV = 1.000 |                  

| KSC = 0.910 K_SCP = 1.000 KSE = 1.000 KST = 1.000 KZB = 1.000 |             

| KZV = 1.000 KZT = 1.000 KZCP = 1.000 K_ZC = 1.050 CHIX = 1.000 |            

| CV = 1.000 KN = 1.000 |                                                     

| |                                                                           

| ACTUAL LOADS : (KN-m) |                                                     

| Pu = 114.000 |                                                              

| Tu = 0.000 |                                                                

| Muy = 0.000 |                                                               

| Muz = 0.000 |                                                               

| V = 0.000 |                                                                 

| SLENDERNESS_Y = 26.178 |                                                    

| SLENDERNESS_Z = 26.178 |                                                    

| ALLOWABLE CAPACITIES OF THE SECTION: (KN-m) |                               

| PY = 129.223 |                                                              

International Design Codes Manual — 239

Page 250: International Codes v8i

| PZ = 129.223 |                                                              

| T = 0.000 |                                                                 

| MY = 0.000 |                                                                

| MZ = 0.000 |                                                                

| V = 0.000 |                                                                 

| SLENDERNESS = 50.000 |                                                      

|--------------------------------------------------------------------------|  

Verification Problem: 5

Objective: - To determine the bending capacity of a Canadian sawn sectionsingle span floor beam.

Design Code: - Canadian wood design code (CSA:086-01)

Reference:- Example 1, page 58, Canadian Wood Design Manual, 2001    

Given:- Length =6000mm, Beam Spacing = 3000mm, Standard load condition,Dry service condition, Untreated           

Comparison: -

Solution Design Strengthin bending (kN-m)

DesignStrength inshear (kN)

Theory 79.8 46.1STAAD 79.732 46.170Difference -0.085% No

Input: -

STAAD PLANE EXAMPLE FOR DIMENSIONAL LUMBER: SAWN_LUMBER_BEAM.STD

START JOB INFORMATION

ENGINEER DATE 08-JUN-05

END JOB INFORMATION

UNIT METER KN

240— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 251: International Codes v8i

JOINT COORDINATES

1 0 0 0; 2 6 0 0; 3 3 0 0;

MEMBER INCIDENCES

1 1 3; 2 3 2;

UNIT FEET POUND

DEFINEMATERIAL START

ISOTROPIC DFL_NO1_10X16_BM

E 1.728E+006

POISSON 0.15

DENSITY 25

ALPHA 5.5E-006

END DEFINEMATERIAL

UNIT METER KN

CONSTANTS

MATERIAL DFL_NO1_10X16_BMMEMB 1 2

UNIT FEET POUND

MEMBER PROPERTYTIMBER CANADIAN

1 2 TABLE ST DFL_NO1_10X16_BM

SUPPORTS

1 2 FIXED

UNIT METER KN

LOAD 1 DEAD+LIVE LOAD

MEMBER LOAD

1 2 UNIGY -16.4

PERFORMANALYSIS

PARAMETER

CODE TIMBER CANADIAN

KD 1.0 ALL

K_T 1.0 ALL

KSB 1.0 ALL

International Design Codes Manual — 241

Page 252: International Codes v8i

KZB 0.90 ALL

KZV 0.90 ALL

K_ZC 1.05 ALL

CHECK CODE ALL

FINISH

Relevant portion of Output:

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)  

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/                     

FX MY MZ LOCATION                                                       

======================================================================= 

2 ST DFL_NO1_10X16_BM

FAIL CL.5.5.5/6.5.6 1.066 1                                              

0.00 T 0.00 49.20 3.0000                                              

|--------------------------------------------------------------------------|  

| LEZ = 3000.000 LEY = 3000.000 LUZ = 3000.000 LUY = 3000.000mm |             

| |                                                                           

| KD = 1.000 KH = 1.000 KT = 1.000 KSB = 1.000 KSV = 1.000 |                  

| KSC = 1.000 K_SCP = 1.000 KSE = 1.000 KST = 1.000 KZB = 0.900 |             

| KZV = 0.900 KZT = 1.000 KZCP = 1.000 K_ZC = 1.050 CHIX = 1.000 |            

| CV = 1.000 KN = 1.000 |                                                     

| |                                                                           

| ACTUAL LOADS : (KN-m) |                                                     

| Pu = 0.000 |                                                                

| Tu = 0.000 |                                                                

| Muy = 0.000 |                                                               

242— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 253: International Codes v8i

| Muz = 49.200 |                                                              

| V = -49.200 |                                                               

| SLENDERNESS_Y = 4.511 |                                                     

| SLENDERNESS_Z = 2.158 |                                                     

| ALLOWABLE CAPACITIES OF THE SECTION: (KN-m) |                               

| PY = 0.000 |                                                                

| PZ = 0.000 |                                                                

| T = 0.000 |                                                                 

| MY = 79.800 |                                                               

| MZ = 79.732 |                                                               

| V = 46.170 |                                                                

| SLENDERNESS = 50.000 |                                                      

|--------------------------------------------------------------------------|  

Verification Problem: 6

Objective:- To determine the capacity of a Canadian Sawn section in axial tension.

Design Code: - Canadian wood design code (CSA:086-01)

Reference:- Example 2, page 158, Canadian Wood Design Manual, 2001    

Given:- Dry service condition, Untreated            

Comparison: -

Solution DesignStrength inTension(kN)

Theory 185STAAD 184.338Difference -0.357 %

Input: -

International Design Codes Manual — 243

Page 254: International Codes v8i

STAAD PLANE EXAMPLE FOR DIMENSIONAL LUMBER SAWN_LUMBER_TENSION.STD

START JOB INFORMATION

ENGINEER DATE 08-JUN-05

END JOB INFORMATION

UNIT FEET POUND

JOINT COORDINATES

1 0 0 0; 2 0 16.4042 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC DFL_NO1_6X8_BM

E 1.728E+006

POISSON 0.15

DENSITY 25

ALPHA 5.5E-006

END DEFINEMATERIAL

UNIT METER KN

CONSTANTS

MATERIAL DFL_NO1_6X8_BMMEMB 1

UNIT FEET POUND

MEMBER PROPERTYTIMBER CANADIAN

1 TABLE ST DFL_NO1_6X8_BM

SUPPORTS

1 PINNED

UNIT METER KN

LOAD 1 DEAD+LIVE LOAD

JOINT LOAD

2 FY 144

PERFORMANALYSIS PRINT STATICS CHECK

244— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 255: International Codes v8i

PARAMETER

CODE TIMBER CANADIAN

KH 1.1 ALL

KSC 0.91 ALL

K_ZC 1.05 ALL

CHECK CODE ALL

FINISH

Relevant portion of Output:

STAAD.Pro CODE CHECKING - (S086)

***********************                         

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)   

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/                     

FX MY MZ LOCATION                                                       

======================================================================= 

1 ST DFL_NO1_6X8_BM

PASS CL.5.5.10/6.5.12 0.781 1                                            

144.00 T 0.00 0.00 0.0000                                             

|--------------------------------------------------------------------------|  

| LEZ = 5000.000 LEY = 5000.000 LUZ = 5000.000 LUY = 5000.000mm |             

| |                                                                           

| KD = 1.000 KH = 1.100 KT = 1.000 KSB = 1.000 KSV = 1.000 |                  

| KSC = 0.910 K_SCP = 1.000 KSE = 1.000 KST = 1.000 KZB = 1.000 |             

| KZV = 1.000 KZT = 1.000 KZCP = 1.000 K_ZC = 1.050 CHIX = 1.000 |            

| CV = 1.000 KN = 1.000 |                                                     

| |                                                                           

| ACTUAL LOADS : (KN-m) |                                                     

International Design Codes Manual — 245

Page 256: International Codes v8i

| Pu = 0.000 |                                                                

| Tu = -144.000 |                                                             

| Muy = 0.000 |                                                               

| Muz = 0.000 |                                                               

| V = 0.000 |                                                                 

| ALLOWABLE CAPACITIES OF THE SECTION: (KN-m) |                               

| PY = 0.000 |                                                                

| PZ = 0.000 |                                                                

| T = 184.338 |                                                               

| MY = 0.000 |                                                                

| MZ = 0.000 |                                                                

| V = 0.000 |                                                                 

|--------------------------------------------------------------------------|  

246— STAAD.Pro

Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

Page 257: International Codes v8i

Section 4

Chinese Codes

International Design Codes Manual — 247

Page 258: International Codes v8i

248— STAAD.Pro

Page 259: International Codes v8i

Chinese Codes - Concrete Design Per GB50010-2002

4A.1 Design Operations

STAAD has the capabilities for performing concrete design per GB50010-2002. Itcan calculate the reinforcement needed for sections assigned through thePRISMATIC attribute. The concrete design calculations are based on the limit statemethod of GB50010-2002.

4A.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be designed.

l For Beams — Prismatic (Rectangular, Square, Tee, and Trapezoidal)

l For Columns — Prismatic (Rectangular, Square, and Circular)

4A.3 Member Dimensions

Concrete members which will be designed by the programmust have certainsection properties input under the MEMBER PROPERTY command. The followingexample shows the required input:

UNIT MM

MEMBER PROPERTY

1 3 TO 7 9 PRISM YD 450. ZD 250.

11 13 PR YD 350.

14 TO 16 PRIS YD 400. ZD 750. YB 300. ZB 200.

will be done accordingly. In the above input, the first set of members arerectangular (450 mm depth and 250mmwidth) and the second set of members,with only depth and no width provided, will be assumed to be circular with 350 mmdiameter. The third set numbers in the above example represents a T-shape with750 mm flange width, 200 width, 400 mm overall depth and 100 mm flange depth(See section 6.20.2). The program will determine whether the section isrectangular, flanged or circular and the beam or column design.

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4A.4 Design Parameters

The program contains a number of parameters which are needed to performdesign as per GB50010-2002.  Default parameter values have been selected suchthat they are frequently used numbers for conventional design requirements.These values may be changed to suit the particular design being performed. Table9A.1 of this manual contains a complete list of the available parameters and their default values. It is necessary to declare length and force units as Millimeter andNewton before performing the concrete design. Please note as per GB50010-2002, STAAD supports Characteristic Values of Concrete Strength and DesignValue of Strength of Steel Bar only as per Table 4.1.4 and Table 4.2.3-1respectively.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE CHINESE Design Code to follow.

See section 5.52.2 of the Technical

Reference Manual.

Table 4A.1 - Chinese Concrete Design GB50010-2002 Parameters

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ParameterName

DefaultValue

Description

BRACING 0.0 BEAM DESIGN

A value of 1.0 means the

effect of axial force will be

taken into account for

beam design.

COLUMN DESIGN

A value of 1.0 means the

column is unbraced about

major axis.

A value of 2.0 means the

column is unbraced about

minor axis.

A value of 3.0 means the

column is unbraced about

both axis.

CLEAR 25 mm

40 mm

For beammembers.

For column members

DEPTH YD Total depth to be used for design. This

value defaults to YD as provided

under MEMBER PROPERTIES.

ELZ 1.0 Ratio of effective length to actual

length of column about major axis.

ELY 1.0 Ratio of effective length to actual

length of column about minor axis.

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ParameterName

DefaultValue

Description

FC 15

N/mm2Concrete Yield Stress.

FYMAIN 210

N/mm2Yield Stress for main reinforcing steel.

FYSEC 210

N/mm2Yield Stress for secondary reinforcing

steel.

MAXMAIN 60 mm Maximummain reinforcement bar

size.

MAXSEC 12 mm Maximum secondary reinforcement

bar size.

MINMAIN 10 mm Minimummain reinforcement bar size.

MINSEC 8 mm Minimum secondary reinforcement bar

size.

RATIO 4.0 Maximum percentage of longitudinal

reinforcement in columns.

REINF 0.0 Tied column. A value of 1.0 will mean

spiral reinforcement.

RFACE 4.0 A value of 4.0 means longitudinal

reinforcement in column is arranged

equally along 4 faces.

A value of 2.0 invokes 2 faced

distribution about major axis.

A value of 3.0 invokes 2 faced

distribution about minor axis.

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ParameterName

DefaultValue

Description

TRACK 0.0 BEAM DESIGN:

0.0 = , output consists of

reinforcement details at

START, MIDDLE and END.

1.0 = critical moments are

printed in addition to

TRACK 0.0 output.

2.0 = required steel for

intermediate sections

defined by NSECTION are

printed in addition to

TRACK 1.0 output.

COLUMN DESIGN:

0.0 = reinforcement

details are printed.

1.0 = column interaction

analysis results are printed

in addition to TRACK 0.0

output.

2.0 = a schematic

interaction diagram and

intermediate interaction

values are printed in

addition to TRACK 1.0

output

9.0 = details of section

capacity calculations.

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ParameterName

DefaultValue

Description

WIDTH ZD Width to be used for design. This

value defaults to ZD as provided

under MEMBER PROPERTIES.

4A.5 Beam Design

Beams are designed for flexure, shear and torsion. If required the effect the axialforce may be taken into consideration.  For all these forces, all active beamloadings are prescanned to identify the critical load cases at different sections ofthe beams. The total number of sections considered is 13 (e.g., 0., .1, .2, .25, .3,.4, .5, .6, .7, .75, .8, .9, and 1). All of these sections are scanned to determine thedesign force envelopes.

Design for Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) andhogging (creating tensile stress at the top face) moments are calculated for allactive load cases at each of the above mentioned sections. Each of these sectionsare designed to resist both of these critical sagging and hogging moments. Whereever the rectangular section is inadequate as singly reinforced section, doublyreinforced section is tried. However, presently the flanged section is designed onlyas singly reinforced section under sagging moment. It may also be noted allflanged sections are automatically designed as rectangular section under hoggingmoment as the flange of the beam is ineffective under hogging moment. Flexuraldesign of beams are performed in two passes. In the first pass, effective depths ofthe sections are determined with the assumption of single layer of assumedreinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database insingle or multiple layers. The entire flexure design is performed again in a secondpass taking into account of the changed effective depths of sections calculated onthe basis of reinforcement provide after the preliminary design. Final provision offlexural reinforcements is made then. Efforts have been made to meet theguideline for the reinforcement detailing as per GB50010-2002 Although exactcurtailment lengths are not mentioned explicitly in the design output (finally whichwill be more or less guided by the detailer taking into account of other practical

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consideration), user has the choice of printing reinforcements provided by STAADat 11 equally spaced sections from which the final detail drawing can be prepared.

Design for Shear

Shear reinforcement is calculated to resist both shear forces and torsionalmoments. Shear design are performed at 11 equally spaced sections (0. to 1.) forthe maximum shear forces amongst the active load cases and the associatedtorsional moments. Shear capacity calculation at different sections without theshear reinforcement is based on the actual tensile reinforcement provided bySTAAD program. Two-legged stirrups are provided to take care of the balanceshear forces acting on these sections.

Beam Design Output

The default design output of the beam contains flexural and shear reinforcementprovided at 5 equally spaced (0, .25, .5, .75, and 1.) sections along the length ofthe beam. User has option to get a more detail output. All beam design outputs aregiven in IS units. An example of rectangular beam design output with the defaultoutput option (TRACK 0.0) is presented below:

==========================================-==================================

B E A M  N O.    12   D E S I G N  R E S U L T S

C20                    HRB400 (Main)               HRB400 (Sec.)

LENGTH:  4000.0 mm      SIZE:   250.0 mm X  350.0 mm   COVER:30.0 mm

DESIGN LOAD SUMMARY (KN MET)

----------------------------------------------------------------------------

SECTION |FLEXTURE (Maxm. Sagging/Hogging moments)|          SHEAR

(in mm) |     P        MZ        MX   Load Case  |    VY       MX  Load Case

----------------------------------------------------------------------------

0.0 |     0.00      0.00      0.00     4     |   29.64     1.23      4

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|     0.00    -25.68      1.23     4     |

400.0 |     0.00      0.00      0.00     4     |   27.97     1.23      4

|     0.00  -16.05      1.23     4     |

800.0 |     0.00      0.00      0.00     4     |   25.12     1.23      4

|     0.00     -7.17      1.23     4     |

1200.0 |     0.00      0.97      0.49     5     |   21.11     1.23      4

|     0.00     -0.14      1.32     6     |

1600.0 |     0.00      6.77      1.23     4     |   15.93     1.23      4

|     0.00      0.00      0.00     4     |

2000.0 |     0.00     11.06      1.23     4     |    9.59     1.23      4

|     0.00      0.00      0.00     4     |

2400.0 |     0.00     13.04      1.23     4     |    2.08     1.23      4

|     0.00      0.00      0.00     4     |

2800.0 |     0.00     12.45      1.23     4     |   -5.43 1.23      4

|     0.00      0.00      0.00     4     |

3200.0 |     0.00      9.55      1.23     4     |  -11.77     1.23      4

|     0.00      0.00      0.00     4     |

3600.0 |     0.00      4.73      1.23     4     | -16.95     1.23      4

|     0.00      0.00      0.00     4     |

4000.0 |     0.00      0.00      0.00     4     |  -25.48     1.23      4

|     0.00    -17.36      1.23     4     |

----------------------------------------------------------------------------

SUMMARY OF REINF. AREA (Sq.mm)

----------------------------------------------------------------------------

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SECTION      0.0 mm     1000.0 mm     2000.0 mm     3000.0 mm    4000.0 mm

----------------------------------------------------------------------------

TOP         259.04        161.29          0.00          0.00        176.31

REINF.      (Sq. mm)      (Sq. mm)      (Sq. mm)      (Sq. mm)      (Sq.mm)

BOTTOM         0.00        160.78        160.78        160.78          0.00

REINF.      (Sq. mm)      (Sq. mm)      (Sq. mm)      (Sq. mm)      (Sq.mm)

----------------------------------------------------------------------------

SUMMARY OF PROVIDED REINF. AREA

----------------------------------------------------------------------------

SECTION      0.0 mm     1000.0 mm     2000.0 mm     3000.0 mm    4000.0 mm

----------------------------------------------------------------------------

TOP       4-10Ø         3-10Ø         2-10Ø         2-10Ø         3-10Ø

REINF.   1 layer(s)    1 layer(s)    1 layer(s)    1 layer(s)    1 layer(s)

BOTTOM     2-12Ø         2-12Ø         2-12Ø         2-12Ø         2-12Ø

REINF.   1 layer(s)    1 layer(s)    1 layer(s)    1 layer(s)    1 layer(s)

SHEAR   2 legged  8Ø  2 legged  8Ø  2 legged  8Ø  2 legged  8Ø  2legged  8Ø

REINF. @ 100 mm c/c @ 100 mm c/c @ 100 mm c/c @ 100 mm c/c @ 100 mm c/c

----------------------------------------------------------------------------

============================================================================

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4A.6 Column Design

Columns are designed for axial forces and biaxial moments at the ends. All activeload cases are tested to calculate reinforcement. The loading which yield maximumreinforcement is called the critical load. Column design is done for square,rectangular and circular sections. By default, square and rectangular columns anddesigned with reinforcement distributed on each side equally for the sectionsunder biaxial moments and with reinforcement distributed equally in two faces forsections under uniaxial moment. User may change the default arrangement of thereinforcement with the help of the parameter RFACE (see Table 4A.1). Dependingupon the member lengths, section dimensions and effective length coefficientsspecified by the user STAAD automatically determine the criterion (short or long)of the column design. All major criteria for selecting longitudinal and transversereinforcement as stipulated by GB50010-2002 have been taken care of in thecolumn design of STAAD.

Column  Design  Output

Default column design output (TRACK 0.0) contains the reinforcement provided bySTAAD and the capacity of the section. With the option TRACK 1.0, the outputcontains intermediate results such as the design forces, effective lengthcoefficients, additional moments etc. A special output TRACK 9.0 is introduced toobtain the details of section capacity calculations. All design output is given in SIunits. An example of  a long column design output (with option TRACK 1.0) isgiven below.

=========================================-===================================

C O L U M N   No.    1   D E S I G N   R E S U L T S

C20                    HRB400 (Main)               HRB400 (Sec.)

LENGTH:  3000.0 mm   CROSS SECTION:  250.0 mm dia.  COVER:40.0 mm

** GUIDING LOAD CASE:   5  BRACED LONG COLUMN

DESIGN FORCES (KNS-MET)

-----------------------

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DESIGN AXIAL FORCE (Pu)             :    62.0

About Z         About Y

INITIAL MOMENTS                     :    2.21           32.29

MOMENTS DUE TO MINIMUM ECC.         :    1.24            1.24

SLENDERNESS RATIOS                  :   12.00           12.00

MOMENTS DUE TO SLENDERNESS EFFECT   :    1.12            1.12

MOMENT REDUCTION FACTORS            :    1.00            1.00

ADDITION MOMENTS (Maz and May)      :    1.12            1.12

TOTAL DESIGN MOMENTS                :    3.32           33.40

REQD. STEEL AREA   :   1822.71 Sq.mm.

MAIN REINFORCEMENT : Provide  17 - 12 dia. (3.92%,   1922.65Sq.mm.)

(Equally distributed)

TIE REINFORCEMENT  : Provide  8 mm dia. rectangular ties @ 190mm c/c

SECTION CAPACITY (KNS-MET)

--------------------------

Puz :    992.70   Muz1 :     36.87   Muy1 :     36.87

INTERACTION RATIO: 1.00

============================================================================

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4B.1 General

his section presents some general statements regarding the implementation inSTAAD of the National Standard of the People’s Republic of China specifications forDesign of Steel Structures (GB50017-2003). The design philosophy and procedurallogistics are based on the principles of limit state design method. Facilities areavailable for member selection as well as code checking. The following sectionsdescribe the salient features of the design approach.

Members are proportioned to resist the design loads without exceedance of thecapacities. The most economical section is selected on the basis of the least weightcriteria. The code checking part of the program also checks the slendernessrequirements and the stability criteria. It is generally assumed that the user will takecare of the detailing requirements like flange buckling, web crippling etc. Users arerecommended to adopt the following steps in performing the steel design: 

1. Specify the geometry and factored loads. Perform the analysis.

2. Specify the design parameter values if different from the default values.

3. Specify whether to perform code checking or member selection.

4B.2 Analysis  Methodology

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loading specificationsand using appropriate load factors to create necessary loading situations.Depending upon the analysis requirements, regular stiffness analysis, P-Deltaanalysis or Non-linear analysis may be specified. Dynamic analysis may also beperformed and the results combined with static analysis results.

4B.3 Member  Property  Specifications

For specification of member properties, the steel section library available in STAADmay be used. The next section describes the syntax of commands used to assignproperties from the built-in steel table. Member properties may also be specified

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using the User Table facility. For more information on these facilities, refer to theSTAAD Program Technical Reference manual.

4B.4 Built-in Chinese Steel Section Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, the properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredfor these members. An example of the member property specification in an inputfile is provided at the end of this section.

A complete listing of the sections available in the built-in steel section library maybe obtained by using the tools of the graphical user interface.

Following are the descriptions of different types of sections. 

I Shapes

I shaped sections are designated in the following way.

1 TO 5 15 16 TABLE ST I22B

H Shapes

H shaped sections are designated in the following way.

6 TO 8 TABLE ST HW250X250

T Shapes

T shaped sections are designated in the following way.

24 25 33 TO 36 TABLE ST TM244X300

Channels

Channels are specified in the following way.

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29 30 TABLE ST CH25A

Double Channels

Back to back double channels, with or without a spacing between them, areavailable. The letter D in front of the section name will specify a double channel.

11 TABLE D CH22B

17 TABLE D CH40C SP 0.15

In the above set of commands, member 11 is a back-to-back double channelCH22B with no spacing in between. Member 17 is a double channel CH40C with aspacing of 0.15 length units between the channels. 

Angles

Two types of specifications may be used to describe an angle. The standard anglesection is specified as follows:

19 TABLE ST L100X100X7

Two types of specifications may be used to describe an angle. The standard anglesection is specified as follows:

27 TABLE RA L40X25X3

The above section signifies an angle with legs of length 40mm and 25mm and a legthickness of 3 mm. This specification may be used when the local Z axiscorresponds to the z-z axis specified in Chapter 2. If the local Y axis corresponds tothe z-z axis, type specification "RA" (reverse angle) may be used.

Double Angles

Short leg back-to-back or long leg back-to-back double angles can be specified bymeans of input of the words SD or LD, respectively, in front of the angle size. Incase of an equal angle, either SD or LD will serve the purpose.

22 TABLE LD L56X36X3

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32 TABLE SD L45X28X4

20 TABLE LD L56X36X3 SP 0.15

28 TABLE SD L56X36X4 SP 0.15

Tubes (Rectangular or Square Hollow Sections)

Tubes can be assigned in 2 ways. In the first method, the designation for the tubeis as shown below. This method is meant for tubes whose property name isavailable in the steel table. In these examples, member 12 consist of a 10X6X0.3cm size tube section,

12 TABLE ST TUB100603.0

In the second method, tubes are specified by their dimensions. For example,

13 TABLE ST TUBE TH 0.15WT 0.8 DT 0.6

is a tube that has a height of 0.6 length units, width of 0.6 length units, and a wallthickness of 0.15 length units.

Pipes (Circular Hollow Sections)

Pipes can be assigned in 2 ways. In the first method, the designation for the pipeis as shown below. This method is meant for pipes whose property name isavailable in the steel table.

21 31 TABLE ST PIP203X6.5

In the second method, pipe sections may be provided by specifying the word PIPEfollowed by the outside and inside diameters of the section. For example,

9 10 14 18 23 26 TABLE ST PIPE OD 0.6 ID 0.55

specifies a pipe with outside diameter of 0.6 length units and inside diameter of.55 length units.

Sample File Containing Chinese Shapes

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STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 04-AUG-05

END JOB INFORMATION

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 4 0 0; 3 9 0 0; 4 0 0 4; 5 4 0 4; 6 0 0 8; 7 4 0 8; 8 9 0 8;

9 0 3.5 0; 10 4 3.5 0; 11 9 3.5 0; 12 0 3.5 4; 13 4 3.5 4; 14 0 3.5 8;

15 4 3.5 8; 16 9 3.5 8; 17 0 7 0; 18 4 7 0; 19 9 7 0; 20 0 7 4;

21 4 7 4; 22 0 7 8; 23 4 7 8; 24 9 7 8;

MEMBER INCIDENCES

1 1 9; 2 2 10; 3 3 11; 4 4 12; 5 5 13; 6 6 14; 7 7 15; 8 8 16; 9 9 17;

10 10 18; 11 11 19; 12 12 20; 13 13 21; 14 14 22; 15 15 23; 16 16 24;

17 9 10; 18 10 11; 19 12 13; 20 14 15; 21 15 16; 22 17 18; 23 18 19;

24 20 21; 25 22 23; 26 23 24; 27 9 12; 28 12 14; 29 10 13; 30 13 15;

31 11 16; 32 17 20; 33 20 22; 34 18 21; 35 21 23; 36 19 24;

MEMBER PROPERTYCHINESE

*I SHAPES

1 TO 5 15 16 TABLE ST I22B

*H SHAPES

6 TO 8 TABLE ST HW250X250

*T SHAPES

24 25 33 TO 36 TABLE ST TM244X300

*CHANNELS

29 30 TABLE ST CH25A

*DOUBLE CHANNELS

11 TABLE D CH22B

17 TABLE D CH40C SP 0.15

*ANGLES

19 TABLE ST L100X100X7

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*DOUBLE ANGLES

27 TABLE RA L40X25X3

22 TABLE LD L56X36X3

32 TABLE SD L45X28X4

20 TABLE LD L56X36X3 SP 0.15

28 TABLE SD L56X36X4 SP 0.15

*TUBES

12 TABLE ST TUB100603.0

13 TABLE ST TUBE TH 0.15WT 0.8 DT 0.6

*PIPES

21 31 TABLE ST PIP203X6.5

9 10 14 18 23 26 TABLE ST PIPE OD 0.6 ID 0.55

PRINT MEMBER PROPERTIES

FINISH

4B.5 Member  Capacities

The basic measure of member capacities are the allowable stresses on the memberunder various conditions of applied loading such as allowable tensile stress,allowable compressive stress etc. These depend on several factors such as crosssectional properties, slenderness factors, unsupported width to thickness ratiosand so on. Explained here is the procedure adopted in STAAD for calculating suchcapacities.

Allowable stress for Axial Tension

In members with axial tension, the tensile load must not exceed the tensioncapacity of the member. The tension capacity of the member is calculated on thebasis of allowable tensile stresses provided in Table 3.4.1-1 of the code. STAADcalculates the tension capacity of a given member per this allowable stress valueand a user supplied net section factor (NSF-a default value of 1.0 is present butmay be altered by changing the input value, see Table 1) and proceeds withmember selection or code checking.

Allowable stress for Axial Compression

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The allowable stress for members in compression is determined according to Table3.4.1-1. Compressive resistance is a function of the slenderness of the cross-section (Kl/r ratio) and the user may control the slenderness value by modifyingparameters such as KY, LY, KZ and LZ. The provisions of Section 5 are used tocheck the adequacy of sections in compression.

Allowable stress for Bending and Shear

Sections subjected to bending moments and shear forces are to be designedaccording to the provisions of section 4. The permissible bending compressive andtensile stresses are dependent on such factors as outstanding legs and thickness offlanges, unsupported length of the compression flange (UNL, defaults to memberlength) etc. Shear capacities are calculated according to Table 3.4.1-1 and Section4 and are a function of web depth, web thickness etc. Users may use a value of 1.0or 2.0 for the TRACK parameter to obtain a listing of the bending and shearcapacities.

Allowable stress for Combined Loading

For members experiencing combined loading (axial force, bending and shear),applicable interaction formulas are checked at different locations of the member forall modeled loading situations. The procedure of Section 5 is implemented forcombined axial load and bending.

4B.6 Combined  Loading

For members experiencing combined loading (axial force, bending and shear),applicable interaction formulas are checked at different locations of the member forall modeled loading situations. The procedure of Section 5 is implemented forcombined axial load and bending.

4B.7 Design Parameters

The user is allowed complete control over the design process through the use ofparameters mentioned in Table 4B.1. These parameters communicate designdecisions from the engineer to the program. 

The default parameter values have been selected such that they are frequently usednumbers for conventional design. Depending on the particular design requirementsof an analysis, some or all of these parameter values may have to be changed toexactly model the physical structure.

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Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Definition Code Ref-erence

Notes

CODE CHINESE

Design Code tofollow.

See section5.48.1 of theTechnicalReferenceManual.

- -

BEAM 1 Beam parameter -

0 = Performdesign at endsand thoselocationsspecified in thesectioncommand.

1 = Performdesign at endsand 1/12thsection locationsalong memberlength.

COMPRESSION

150Allowable KL/rvalue incompression

- -

DMAX 100 cmMaximumallowable depth

- -

DMIN 0 cmMinimumrequired depth

- -

Table 4B.1 - Chinese Steel Design GBJ 50017-2003 Parameters

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ParameterName

DefaultValue

Definition Code Ref-erence

Notes

GRADE 1 Grade of steelClause3.4.1

The Followingvalues representthe variousgrades of steel.

Q235 - 1

Q345 - 2

Q390 - 3

Q420 - 4

KY 1K value in local Y-axis, usuallyminor axis

- -

KZ 1K value in local Z-axis, usuallymajor axis

- -

LY 0

Length in local Yaxis forslenderness valueKL/r

-Default isselected beam'slength

LZ 0

Length in local Zaxis forslenderness valueKL/r

-Default isselected beam'slength

MAIN -

Flag forcontrollingslendernesscheck

-

0 = Check forslenderness.

1 = Do not checkfor slenderness

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ParameterName

DefaultValue

Definition Code Ref-erence

Notes

NSF 1Net section factorfor tensionmembers

- -

RATIO 1Permissible ratioof actual toallowable stress

- -

PFY 1.2Plasticityadaptation factorY direction

Table -5.2.1

-

PFZ 1.05Plasticityadaptation factorZ direction

Table -5.2.1

-

SBY 1Overall Stabilityfactor for Ydirection

Appendix-B

-

SBZ 0Overall Stabilityfactor for Zdirection

Appendix-B

-

SFY 1Stability factorfor Y direction

Appendix-C

Stability factorfor axialcompressionmembers shall beselected fromappendix –Cbased on itsslendernessratio, yieldstrength,classification ofthe section inTable 5.1.2-1and Table 5.1.2-2

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ParameterName

DefaultValue

Definition Code Ref-erence

Notes

SFZ 1Stability factorfor Z direction

Appendix-C

Stability factorfor axialcompressionmembers shall beselected fromappendix –Cbased on itsslendernessratio, yieldstrength,classification ofthe section inTable 5.1.2-1and Table 5.1.2-2

TENSION 300Allowable KL/rvalue in tension

- -

TRACK 0 Track parameter -

0 = Suppresscritical memberstress.

1 = Print allcritical memberstress.

2 = Printexpandedoutput.

4B.8 Code Checking

The purpose of code checking is to check whether the provided section propertiesof the members are adequate. The adequacy is checked per the GB50017-2003requirements.

Code checking is done using forces and moments at specified sections of themembers. If the BEAM parameter for a member is set to 1, moments are calculated

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at every twelfth point along the beam, and the maximummoment about the majoraxis is used. When no sections are specified and the BEAM parameter is set to zero(default), design will be based on member start and end forces. The code checkingoutput labels the members as PASSed or FAILed. In addition, the critical condition,governing load case, location (distance from start joint) and magnitudes of thegoverning forces and moments are also printed.

Refer to Section 5.48.2 of the Technical Reference Manual for further informationon this feature.

Example

Sample Input data for Chinese Code Steel Design

UNIT METER

PARAMETER

CODE CHINESE

NSF 0.85 ALL

GRADE 3.0 MEMBER 7

KY 1.2 MEMBER 3 4

RATIO 0.9 ALL

TRACK 1.0 ALL

CHECK CODE AL

4B.9 Member Selection

The member selection process basically involves determination of the least weightmember that PASSes the code checking procedure based on the forces andmoments of the most recent analysis. The section selected will be of the same typeas that specified initially. For example, a member specified initially as a channelwill have a channel selected for it. Selection of members whose properties areoriginally provided from a user table will be limited to sections in the user table.

Refer to Section 5.48.3 of the Technical Reference Manual for further informationon this feature.

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Section 5

European Codes

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European Codes - Concrete Design Per Euro-code EC2

5A.1 Design Operations

STAAD provides a comprehensive set of national codes for the design of concretestructures. In general, all the available codes, including EC2, follow the sameprocedure for the design of the concrete members.

The main steps in performing a design operation are:

1. Selecting the applicable load cases to be considered in the design process.

2. Providing appropriate parameter values if different from the default values.

3. Perform the design for the member as appropriate.

These operations can be repeated by the user any number of times depending onthe design requirements. The parameters referred to above provide the user withthe ability to allocate specific design properties to individual members considered inthe design operation.

5A.2   Eurocode 2 (EC2)

Eurocode 2, Design of concrete structures, Part 1, General rules and rules forbuildings, provides design rules applicable to plain, reinforced or prestressedconcrete used in buildings and civil engineering works. It is based on the limit statephilosophy common to modern standards.

The objective of this method of design is to ensure that possibility of failure isreduced to a negligible level. This is achieved through application of factors to boththe applied loads and the material properties. The code also provides guidelines onthe global method of analysis to be used for calculating internal member forces andmoments. STAAD provides a number of methods for analysis, allowing GeometricNonlinearity as well as P-Delta effects to be considered.

5A.3 National Application Documents

Various authorities of the CEN member countries have prepared NationalApplication Documents to be used with EC2. These documents provide alternativefactors for loads and may also provide supplements to the rules in EC2.

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The current version of EC2 implemented in STAAD adheres to the factors and rulesprovided in EC2 and has not been modified by any National ApplicationDocuments.

5A.4 Material Properties and Load Factors

Design resistances are obtained by dividing the characteristic yield strengths, asgiven in table 2.3 of EC2, by the material partial safety factors γ

cfor concrete and

γsfor reinforcements. The magnitude in STAAD is 1.5 for concrete and 1.15 for

reinforcements.

Material coefficients in STAAD take the following default values unless replaced bynumerical values provided in the input file.

Modulus of Elasticity, E = 21.71 KN/mm2

Shear Modulus, G = E / 2 (1 + v)

Poisson's Ratio, v = 0.25

Unit weight, ρ = 23.56 KN/m3

The magnitude of design loads is dependent on γF, the partial safety factor for the

action under consideration. In STAAD the user is allowed total control in providingapplicable values for the factors and their use in various load combinations.

5A.5 Columns

Columns are designed for axial compressive loads and possible moments at theends of the member. If a particular load case causes tension in the column beingdesigned that load case is ignored, the design proceeds with a warning messagegiven to that affect.

All active load cases will be considered in the design and reinforcements areassumed symmetrically arranged in the cross section.

The maximum reinforcement calculated after all design load cases have beenconsidered is then reported as the critical required area of reinforcement.

Slender columns are also covered in the design process, the program will makedue allowance for the additional moment that has to be considered in the design.

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Note: Sway type structures are not directly covered in the currentimplementation of EC2. This effect, however, can be accounted for by the P-DELTA analysis option.

5A.6 Beams

Beams are designed for flexure, shear and torsion. For all these actions active loadcases are scanned to create appropriate envelopes for the design process.Maximum torsional moment is also identified and incorporated in the design.

Design for flexure

Reinforcement for both positive and negative moments is calculated on the basis ofthe section properties provided by the user. If the required reinforcement exceedsthe maximum allowable then the section size is inadequate and a massage to thateffect is given in the output. Parabolic-rectangular stress distribution for theconcrete section is adopted and as moment redistribution is not available in STAADanalysis, the limit for N.A to depth ratio is set according to clause 2.5.3.4.2 (5) ofthe code.

If required, compression reinforcement will be provided in order to satisfy theabove limits. It is important to know that beams are designed for the flexuralmoment MZ only. The moment MY is not considered in the design at all.

Design for Shear

Shear reinforcement design is based on the standard method mentioned in clause4.3.2.4.3 where it is assumed the notional strut inclination is constant. Dependingon the shear distribution within the member it may be possible that nominal shearreinforcement will be sufficient to cater for the design shear forces. If this is not thecase an attempt is made to identify regions where nominal reinforcement isinsufficient and appropriate reinforcement is then calculated to cover the excessdesign shear force.

The maximum shear force that can be carried without crushing the concrete is alsochecked and if exceeded, a message to revise the section size is given in the outputfile.

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Design for Torsion

Torsional moments arising as a result of equilibrium requirements need to bedesigned for at the ultimate limit state. Reinforcement for torsional momentsconsists of stirrups combined with longitudinal bars. The combined magnitude ofshear stress arising from shear forces and torsional moments are checked in orderto establish whether the section size is adequate. If section size is inadequate amassage is given in the output file, otherwise, full design is carried out and bothshear links and longitudinal bars required are calculated and, where necessary,links are combined with the shear force links and printed in a tabulated manner inthe output file.

5A.7 Slabs

Slabs can only be designed for if finite elements are used to represent them in themodel of the structure. In the main the design follows the same procedure as forflexure except that shear forces are assumed to be resisted without the provisionof shear reinforcements. In cases where this may not be the case users mustensure that necessary checks are carried out. The output for the slab design refersto longitudinal reinforcements, which coincides with the local x direction of theelement, and, transverse reinforcement, which coincides with the local y directionof the element.

Also, reference is made to 'TOP' and BOTT' reinforcement which relates to theelement's 'TOP' and 'BOTTOM' as determined from the connectivity of the element.This may not coincide with the slab's actual top and bottom and, if desired, youmust ensure this through the numbering scheme of the elements. The design ofthe slab considers a fixed bar size of 16mm in both directions with the longitudinalbar being the layer closest to the slab exterior faces. Refer to Figure 1.21 inSection 1.61. of the Technical Reference Manual for additional information.

5A.8 Design Parameters

Design parameters communicate specific design decisions to the program. Theyare set to default values to begin with and may be altered to suite the particularstructure. Depending on the model being designed, the user may have to changesome or all of the parameter default values. Some parameters are unit dependentand when altered, the new setting must be compatible with the active "unit"specification. Table 5A.1 lists all the relevant EC2 parameters together withdescription and default values.

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Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

Default Value Description

FYMAIN *460 N/mm2 Yield Stress for mainreinforcement (For slabs, it is forreinforcement in both directions)

FYSEC *460N/mm2 Yield Stress for secondaryreinforcement. Applicable toshear bars in beams

FC * 30N/mm2 Concrete Yield Stress / cubestrength

MINMAIN 8mm Minimummain reinforcement barsize Acceptable bar sizes: 6 8 1012 16 20 25 32 40 50

MINSEC 8mm Minimum secondary bar size a.Applicable to shearreinforcement in beams

CLEAR * 20mm Clearance of reinforcementmeasured from concrete surfaceto closest bar perimeter.

MAXMAIN 50mm Maximum requiredreinforcement bar sizeAcceptable bars are perMINMAIN above.

SFACE *0.0 Face of support location at startof beam. (Only applicable forshear - use MEMBER OFFSET forbending )

EFACE *0.0 Face of support location at endof beam.

Table 5A.1 - Concrete Design EC2 Parameters

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ParameterName

Default Value Description

Note: Both SFACE & EFACEmust be positive numbers.

TRACK 0.0 0.0 =  Critical Moment will notbe printed with beam designreport. Column design gives nodetailed results.

1.0 =  For beam gives min/maxsteel % and spacing. Forcolumns gives a detailed table ofoutput with additional momentscalculated.

2.0 =  Output of TRACK 1.0List of design sag/hog momentsand corresponding required steelarea at each section of member

MMAG 1.0 Factor by which column designmoments are magnified

NSECTION 10 Number of equally-spacedsections to be considered infinding critical moment for beamdesign. The upper limit is 20.

WIDTH *ZD Width of concrete member. Thisvalue default is as provided asZD in MEMBER PROPERTIES.

DEPTH *YD Depth of concrete member. Thisvalue default is as provided asYD in MEMBER PROPERTIES.

BRACE 0.0 0.0 =  Column braced in bothdirections.

1.0 =  Column unbraced aboutlocal Z direction only

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ParameterName

Default Value Description

2.0 =  Column unbraced aboutlocal Y direction only

3.0 =  Column unbraced in bothY and Z directions

ELY 1.0 Member length factor about localY direction for column design.

ELZ 1.0 Member length factor about localZ direction for column design.

SRA 0.0 0.0 =       Orthogonal rein-forcement layout without con-sidering torsional moment Mxy -slabs only

-500 =    Orthogonalreinforcement layout with Mxyused to calculate Wood & Armermoments for design.

A =          Skew angle consideredin Wood & Armer equationswhere A is the angle in degrees.

SERV 0.0 0.0 =  No serviceability checkperformed.

1.0 =  Perform serviceabilitycheck for beams as if they werecontinuous.

2.0 =  Perform serviceabilitycheck for beams as if they weresimply supported.

3.0 =  Perform serviceabilitycheck for beams as if they werecantilever beams.

* Provided in current unit system

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European Codes - Steel Design Per Eurocode 3The design of structural steel members in accordance with the specificationEurocode 3: Design of steel structures - part 1-1: General Rules and rules forbuildings has been implemented.

Two versions of the code are currently implemented, the EC3_94/1 and BS EN1993-1-1:2005. Additionally, STAAD.Pro has implemented several countries'National Annex documents.

To access the EC3_94/1 edition, specify the commands.

PARAMETERS

CODE

EC3

Or

PARAMETERS

CODE

EURO

To access the BS EN 1993-1-1:2005 edition, specify the commands:

PARAMETERS

CODE

EC3 EN 1993-1-1:2005

5B.(A) European Codes - Steel Design toEurocode 3 [DD ENV 1993-1-1:1992]

5B.1(A) General Description

Introduction

STAAD provides a comprehensive set of national codes for the design of steelstructures. In general, all the available codes, including EC3, follow the same

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procedure to either code-check or select suitable members of an analyzedstructure.

The main steps in performing a design operation are:

1. Selecting the applicable load cases to be considered in the design process.

2. Providing appropriate ‘Parameter’ values if different from the default values.

3. Specify whether to perform code-checking and/or member selection.

These operations can be repeated by the user any number of times depending onthe design requirements.  The ‘Parameters’ referred to above provide the user withthe ability to allocate specific design properties to individual members or membergroups considered in the design operation.

Eurocode 3 DD ENV 1993-1-1:1992 (EC3 DD)

The DD ENV version of Eurocode 3, Design of steel structures, Part 1.1 Generalrules and rules for buildings (EC3 DD) provides design rules applicable tostructural steel used in buildings and civil engineering works. It is based on theultimate limit states philosophy that is common to modern standards. Theobjective of this method of design is to ensure that possibility of failure is reducedto a negligible level. This is achieved through application of safety factors to boththe applied loads and the material properties.

The code also provides guidelines on the global methods of analysis to be used forcalculating internal member forces and moments. STAAD uses the elastic methodof analysis which may be used in all cases. Also there are three types of framingreferred to in EC3. These are “Simple”, “Continuous”, and “Semi-continuous”which reflect the ability of the joints to developing moments under a specificloading condition. In STAAD only “Simple” and “Continuous” joint types can beassumed when carrying out global analysis.

National Application Documents

Various authorities of the CEN member countries have prepared NationalApplication Documents to be used with EC3. These documents provide alternativefactors for loads and may also provide supplements to the rules in EC3.

The current version of EC3 DD implemented in STAAD adheres to the factors andrules provided in DD ENV 1993-1-1:1992 and has not been modified by anyNational Application Document.

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Axes convention in STAAD and EC3By default, STAAD defines the major axis of the cross-section as Z-Z and the minoraxis as Y-Y. A special case where Z-Z is the minor axis and Y-Y is the major axis isavailable if the SET Z UP command is used and is discussed in Section 5.5 of theTechnical Reference Manual. The longitudinal axis of the member is defined as Xand joins the start joint of the member to the end with the same positive direction.

EC3, however, defines the principal cross-section axes in reverse to that of STAAD,but the longitudinal axis is defined in the same way. Both of these axes definitionsfollow the orthogonal right hand rule. See figure below.

Bear this difference in mind when examining the code-check output from STAAD.

Figure 5.1 - Axis convention in STAAD and EC3

5B.2(A)   Analysis Methodology

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loading specificationsand using appropriate load factors to create necessary loading situations.

5B.3(A) Material Properties and Load Factors

The characteristic yield strength of steel used in EC3 DD design is based on table3.1 of the code.  Design resistances are obtained by dividing the characteristic yieldstrength by the material partial safety factor Γm. The magnitude of Γm in STAAD is1.1 which is applicable to all section types. A separate safety factor parameternamed GB1 is used to check the resistance of a member to buckling and also has adefault value of 1.1.

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Material coefficients for steel in STAAD take the following default values unlessreplaced by user’s numerical values provided in the input file.

Modulus of Elasticity, E = 205000 N/mm2  

Shear Modulus, G = E/2(1+ ν)

Poisson’s Ratio, ν = 0.3

Unit weight, Γ = 76.8 KN/m3

The magnitude of design loads is dependent on Γf, the partial safety factor for the

action under consideration. In STAAD the user is allowed total control in providingapplicable values for the factors and their use in various load combinations.

5B.4(A) Section Classification

The occurrence of local buckling of the compression elements of a cross-sectionprevents the development of full section capacity. It is therefore imperative toestablish this possibility prior to determining the section capacities. Cross sectionsare classified in accordance with their geometrical properties and the stress patternon the compression elements. For each load case considered in the designprocess, STAAD determines the section class and calculates the capacitiesaccordingly.

The EC3 DD design module in STAAD can design members with all section profilesthat are of Class 1 2 or 3 as defined in section 5.3.2 of the code. However, thedesign of members that have a ‘Class 4’ section profile are limited to WIDEFLANGE, TEE, SINGLE CHANNEL, SINGLE ANGLE, and RECTANGULAR HOLLOWSECTIONS. Also built-up user sections that are class 4 sections are not dealt within the current version of EC3 design in STAAD.Pro.

Laced and battened members are not considered in the current version of EC3 DDdesign module in STAAD.Pro.

5B.5(A) Member Design

5B.5(A).1 Design of Beams as per DD ENV1993-1-1:1992  EC3 DD design in STAAD.Pro considers members that are primarily in bendingand/or shear as beams and performs cross section and member capacity checks in

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accordance with the code. The main requirement for a beam is to have sufficientcross-section resistance to the applied bending moment and shear force. Thepossibility of lateral-torsional buckling is also taken into consideration when the fulllength of the member has not been laterally restrained.

The bending capacity is primarily a function of the section type and the materialyield strength and is determined according to Cl. 5.4.5 of the code. The shearcapacity and the corresponding shear checks are done as per section 5.4.6 of thecode.

There are four classes of cross-sections defined in EC3. Class 1 and 2 sections canboth attain full capacity with the exception that the class 2 sections cannot sustainsufficient rotation required for plastic analysis of the model. Hence the full plasticsection modulus is used in the design calculations. Class 3 sections, due to localbuckling, cannot develop plastic moment capacity and the yield stress is limited tothe extreme compression fibre of the section. The elastic section modulus is used todetermine the moment capacity for class 3 sections. Class 4 sections do suffer fromlocal buckling and explicit allowance must be made for the reduction in sectionproperties before the moment capacity can be determined. Further, because ofinteraction between shear force and bending moment, the moment resistance ofthe cross-section may be reduced. This, however, does not occur unless the valueof applied shear forces exceeds 50% of the plastic shear capacity of the section. Insuch cases the web is assumed to resist the applied shear force as well ascontributing towards the moment resistance of the cross-section.

As mentioned in the previous section, the design of class 4 sections is limited toWIDE FLANGE, TEE, SINGLE CHANNEL, SINGLE ANGLE, and RECTANGULARHOLLOW SECTIONS. The effective section properties are worked out as describedin Cl. 5.3.5 of the code.

Beams are also checked for lateral-torsional buckling according to section 5.5.2 ofthe code. The buckling capacity is dependent on the section type as well as theunrestrained length, restraint conditions and type of applied loading. The lateraltorsional buckling checks involves the calculation of the ‘Elastic critical moment’,Mcr, which is calculated in STAAD as per the method given in Annex F of the code.

In the presence of a shear force, beams are also checked for shear as per section5.4.6 of the code. In cases where the members are subject to combined bendingand shear, the combined bending and shear checks are done in STAAD as perclause 5.4.7 of the code.

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5B.5(A).2 Design of Axially LoadedMembersThe design of members subject to tension loads alone are performed as per Cl5.4.3 of the code. The tension capacity is calculated based on yield strength,material factor Γm and cross-sectional area of the member with possible reductiondue to bolt holes. When bolt holes need to be considered in the capacitycalculations the value used for Γm is 1.2 and the yield strength is replaced with theultimate tensile strength of the material. The tension capacity is then taken as thesmaller of the full section capacity and the reduced section capacity as statedabove.

The design of members subject to axial compression loads alone are performed asper Cl 5.4.4 of the code. For members with class 1 2 or 3 section profiles, the fullsection area is considered in calculating the section capacity. However in case ofclass 4 sections, the ‘effective cross-section’ is considered to calculate thecompressive strength. Also any additional moments induced in the section due tothe shift of the centroidal axis of the effective section will also be taken intoaccount as per clause 5.4.8.3 of the code. The effective section properties for class4 sections will be worked out as given in Cl.5.3.5 of the code.

In addition to the cross section checks, buckling resistance will also be checked forsuch members. This is often the critical case as the buckling strength of themember is influenced by a number of factors including the section type and theunbraced length of the member. The buckling capacity is calculated as per Cl. 5.5of the code.

DD ENV 1993-1-1:1992 does not specifically deal with single angle, doubleangles, double channels or Tee sections and does give a method to work out theslenderness of such members. In these cases, the EC3 DD design module ofSTAAD.Pro uses the methods specified in BS 5950-1:2000 to calculate theslenderness of these members. Cl. 4.7.10 and table 25 of BS 5950-1:2000 areused in the current version of the EC3 DD design module

Single  Angle  SectionsAngle sections are un-symmetrical and when using BS 5950:2000 table 25 youmust consider four axes: two principal, u-u and v-v and two geometric, a-a and b-b. The effective length for the v-v axis, Lvv, is taken as the LVV parameter or LY *KY, if not specified.  The a-a and b-b axes are determined by which leg of the angle

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is fixed by the connection and should be specified using the LEG parameter, seesection 5B.6 for more information on the LEG parameter.  The effective length inthe a-a axis is taken as LY * KY and the effective length in the b-b axis as LZ * KZ.

The following diagram shows the axes for angles which have been defined witheither an ST or RA specification and is connected by its longer leg (i.e., a-a axis isparallel to the longer leg).

Figure 5.2 - Single angle sections A) ST angle & USER table angles and B) RA angle

5B.5(A).3 Design of members with com-bined axial load and bendingThe bending resistance of members could be reduced by the presence of a co-existent axial load. This is then checked against the lateral-torsional bucklingresistance of the section. The EC3 DD design module in STAAD takes such ascenario into account and performs the necessary checks as per Cl. 5.4.8 of thecode. Class 1 and class 2 sections are checked as per cl. 5.4.8.1 and Class 3 andClass 4 sections are checked as per clauses 5.4.8.2 and 5.4.8.3 respectively. Theeffective section properties for class 4 sections are worked out as given in Cl. 5.3.5of the code.

Generally, EC3 requires checking cross-section resistance for local capacity andalso checking the overall buckling capacity of the member. In the case of memberssubject to axial tension and bending, there is provision to take the stabilizing effectof the tension load into consideration. This is achieved by modifying the extreme

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compression fibre stress and calculating an effective applied moment for thesection. The checks are done as per Cl. 5.5.3 of the code. In case of a combinedaxial compressive load and bending moment, the member will be checked as perthe rules in section 5.5.4 of the code.

The presence of large shear force can also reduce the bending resistance of thesection under consideration. If the shear load is large enough to cause a reductionin bending resistance, then the reduction due to shear has to be taken into accountbefore calculating the effect of the axial load on the bending resistance of thesection. If the member is subject to a combined shear, axial load and bendingmoment then the section capacity checks will be done as per Cl. 5.4.9 of the code.

As stated in the previous section, DD ENV 1993-1-1:1992 does not specificallydeal with single angle, double angles, double channels or Tee sections and doesgive a method to work out the slenderness of such members. In these cases, theEC3 DD design module of STAAD.Pro uses the methods specified in BS 5950-1:2000 to calculate the slenderness of these members. Cl. 4.7.10 of BS 5950-1:2000 is used in the current version of the EC3 DD design module. Please refer tothe note in section 5B.5.2 for St and RA angle specifications.

Please note that laced or battened compression members are not dealt within thecurrent version of EC3 DD design module in STAAD.Pro.

5B.6(A) Design Parameters

Design parameters communicate specific design decisions to the program. Theyare set to default values to begin with and may be altered to suite the particularstructure.

Depending on the model being designed, the user may have to change some or allof the parameter default values. Some parameters are unit dependent and whenaltered, the new setting must be compatible with the active “unit” specification.

Table 5B.1(A) lists all the relevant EC3 parameters together with description anddefault values.

ParameterName

Default Value Description

CODE Undefined You must specify EC3 orEUROPE.

Table 5B.1 - Steel Design Parameters EC3 DD

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ParameterName

Default Value Description

Design Code to follow.

See section 5.48.1 of the

Technical Reference Manual.

BEAM 3 Parameter to control the

number of sections to checked

along the length of a beam:

0. Check sections with end

forces only

1. Check at location of max-

imum Mz along beam

2. Check sections with end

forces and forces at loca-

tion of BEAM 1.0 check.

3. Check at every 1/13th

point along the beam and

report the maximum

Refer to Note 2 below.

CAN 0 Member will be considered as a

cantilever type member for

deflection checks.

0 indicates that member will

not be treated as a cantilever

member

1 indicates that the member

will be treated as a cantilever

member

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ParameterName

Default Value Description

CMM 1.0 Indicates type of loading on

member. Valid values range

from 1 to 6.

Refer to Table 5B.2 for more

information on its use.

CMN 1.0 Indicates the level of End-

Restraint.

1.0 = No fixity

0.5 = Full fixity   

0.7 = One end free

and other end fixed

DMAX 100.0 cm Maximum allowable depth for

the member.

DMIN 0 Minimum required depth for

the member.

DFF None

(Mandatory for

deflection

check)

Deflection limit

DJ1 Start Joint of

member

Joint No. denoting starting

point for calculation of

"Deflection Length".

DJ2 End Joint of

member

Joint No. denoting end point

for calculation of "Deflection

Length".

FU Ultimate tensile strength of

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ParameterName

Default Value Description

steel

GB1 1.1 Partial safety factor used in

buckling checks for

compression members

GM0 1.1 Corresponds to the Γm0factor

in DD ENV 1993-1-1:1992

GM1 1.1 Corresponds to the Γm1factor

in DD ENV 1993-1-1:1992

GM2 1.1 Corresponds to the Γm2factor

in DD ENV 1993-1-1:1992

KY 1.0 K factor in local y axis.

KZ 1.0 K factor in local z axis.

LEG 0.0 Connection type

Refer to Note 1 below.

LVV Maximum of

Lyy and Lzz

(Lyy is a term

used by

BS5950)

Buckling length for angle about

its principle axis

LY Member Length Compression length in local y

axis, Slenderness ratio =

(KY)*(LY)/(Ryy)

LZ Member Length Compression length in local z

axis, Slenderness ratio =

(KZ)*(LZ)/(Rzz)

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ParameterName

Default Value Description

PY Yield Strength The yield strength default

value is set based on the

default value of the "SGR"

parameter.

NSF 1.0 Net tension factor for tension

capacity calculation.

RATIO 1 Permissible ratio of loading to

capacity.

SBLT 0.0 Indicates if the section is rolled

or built-up.

0.0 = Rolled

1.0 = Built-up    

SGR 0.0 Steel grade as per table 3.1 in

EC3.

0.0 = Fe 360

1.0 = Fe 430

2.0 = Fe 510      

TRACK 0 Controls the level of detail of

output.

0 = minimum

1 = intermediate

2 = maximum

4 = perform a

deflection check

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ParameterName

Default Value Description

See note 3 below.

UNF 1.0 Unsupported buckling length

as a factor of the beam length

UNL Member Length Unrestraint length of member

used in calculating the lateral-

torsional resistance moment of

the member.

ZIV 0.8 Specifies a reduction factor for

vectoral effects to be used in

axial tension checks [Cl

5.5.3(2)]

Notes:

1. LEG – (Ref: Table 25 BS5950)  

The slenderness of single and double angle, channel and tee sections arespecified in BS 5950 table 25 depending on the connection provided at theend of the member (Refer to section 5B.5(A).2). To define the appropriateconnection, a LEG parameter should be assigned to the member.

The following table indicates the value of the LEG parameter required tomatch the BS5950 connection definition:

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Clause Bold Con-figuration

Leg LEGParameter

4.7.10.2

SingleAngle

(a) - 2 bolts shortleg

1.0

longleg

3.0

(b) - 1 bolts shortleg

0.0

longleg

2.0

4.7.10.3DoubleAngles

(a) - 2 bolts shortleg

3.0

longleg

7.0

(b) - 1 bolts shortleg

2.0

longleg

6.0

(c) - 2 bolts longleg

1.0

shortleg

5.0

(d) - 1 bolts longleg

0.0

shortleg

4.0

4.7.10.4Channels

(a) - 2 or more rows ofbolts

1.0

(b) - 1 row of bolts 0.0

Table 5B.2 - LEG Parameter values

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Clause Bold Con-figuration

Leg LEGParameter

4.7.10.5Tee Sec-tions

(a) - 2 or more rows ofbolts

1.0

(b) - 1 row of bolts 0.0

For single angles, the slenderness is calculated for the geometric axes, a-aand b-b as well as the weak v-v axis. The effective lengths of the geometricaxes are defined as:

La = KY * KY

Lb = KZ * LZ

The slenderness calculated for the v-v axis is then used to calculate thecompression strength pc for the weaker principal axis (z-z for ST angles or y-y for RA specified angles). The maximum slenderness of the a-a and b-b axesis used to calculate the compression strength pc for the stronger principalaxis.

Alternatively for single angles where the connection is not known or Table 25is not appropriate, by setting the LEG parameter to 10, slenderness iscalculated for the two principal axes y-y and z-z only. The LVV parameter isnot used.

For double angles, the LVV parameter is available to comply with note 5 intable 25. In addition, if using double angles from user tables, (Refer toSection 1.7.3 of the Technical Reference Manual) an eleventh value, rvv,should be supplied at the end of the ten existing values corresponding to theradius of gyration of the single angle making up the pair.

2. BEAM

Ensure that this parameter is set to either 1 or 2 while performing codechecking for members susceptible to Lateral - Torsional Buckling.

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CMMValue

Loading and Support Conditions

1

2

3

4

5

6

Table 5B.3 - Values for the CMM Parameter

3. Checking beam deflection

With the TRACK parameter set to 4, the members included in a CHECK CODEcommand will be checked for the local axis deflection rather than for thestress capacity using the current LOAD LIST.

If both stress capacity and deflection checks are required, then 2 parameterblocks with code checks are required, one with a TRACK 4 command and onewith a TRACK 0, 1, or 2, thus:

LOAD LIST 1 TO 10

PARAMETER 1

CODE EN 1993

TRACK 2 ALL

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CHECK CODEMEMBER 1

***************************

LOAD LIST 100 TO 110

PARAMETER 2

TRACK 4 ALL

DFF 300 MEMB 1

DJ1 1 MEMB 1

DJ2 4 MEMB 1

CODEMEMB 1

Note: While both sets of code checks will be reported in the output file,only the last code check results are reported in the GUI.

5B.7(A) Code Checking

The purpose of code checking is to ascertain whether the provided sectionproperties of the members are adequate. The adequacy is checked as per DD ENV1993-1-1:1992. Code checking is done using the forces and moments at specificsections of the members.

When code checking is selected, the program calculates and prints whether themembers have passed or failed the checks; the critical condition ; the value of theratio of the critical condition (overstressed for value more than 1.0 or any otherspecified RATIO value); the governing load case, and the location (distance fromthe start of the member of forces in the member where the critical conditionoccurs).

Code checking can be done with any type of steel section listed in Section 2B.4 orany of the user defined sections as described in Section 1.7.3 of the TechnicalReference Manual, with two exceptions; GENERAL and ISECTION. The EC3 DDdesign module does not consider these sections or PRISMATIC sections in itsdesign process.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

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5B.8(A) Member Selection 

STAAD is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section,i.e., the lightest section, which fulfills the code requirements for the specifiedmember. The section selected will be of the same type section as originallydesignated for the member being designed. Member selection can also beconstrained by the parameters DMAX and DMIN, which limits the maximum andminimum depth of the members.

Member selection can be performed with all the types of steel sections with thesame limitations as defined in section 5B.7(A) Code Checking.

Selection of members, whose properties are originally input from a user createdtable, will be limited to sections in the user table.

Member selection cannot be performed on members whose section properties areinput as prismatic or as the limitations specified in section 5.B.7(A).

5B.9(A)   Tabulated Results of Steel Design 

For code checking or member selection, the program produces the results in atabulated fashion. The items in the output table are explained as follows:

a. MEMBER         refers to the member number for which the design isperformed.              

b. TABLE             refers to steel section name, which has been checked againstthe steel code or has been selected.              

c. RESULTS         prints whether the member has PASSED or FAILED. If theRESULT is FAIL, there will be an asterisk (*) mark on front of the member.              

d. CRITICAL COND         refers to the clause in DD ENV 1993-1-1:1992 codewhich governs the design.

e. RATIO             prints the ratio of the actual stresses to allowable stresses forthe critical condition. Normally a value of 1.0 or less will mean the memberhas passed.               

f. LOADING        provides the load case number, which governed the design.              

g. FX, MY, and MZ          provide the axial force, moment in local Y-axis and themoment in local z-axis respectively. Although STAAD does consider all the

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member forces and moments (except torsion) to perform design, only FX, MYand MZ are printed since they are the ones which are of interest, in mostcases.   

h. LOCATION      specifies the actual distance from the start of the member to thesection where design forces govern.              

Note: For a TRACK 2 output, the module will also report all the relevant clausechecks that have been performed and will also indicate the critical ratio and theload case that caused the critical ratio as well as the corresponding forces thatwere used for the respective checks. A TRACK 2 output will also include thevarious design data used for the calculations such as the section modulii,section class, section capacity etc.

5B.(B) European Codes - Steel Design toEurocode 3 [EN 1993-1-1:2005]

5B.1(B) General Description

STAAD provides a comprehensive set of national codes for the design of steelstructures. In general, all the available codes, including EC3, follow the sameprocedure to either code-check or select suitable members of an analyzed structure.

The main steps in performing a design operation are:

1. Selecting the applicable load cases to be considered in the design process.

2. Providing appropriate ‘Parameter’ values if different from the default values.

3. Specify whether to perform code-checking and/or member selection.

These operations can be repeated by the user any number of times depending onthe design requirements. The ‘Parameters’ referred to above provide the user withthe ability to allocate specific design properties to individual members or membergroups considered in the design operation.

Eurocode 3 - EN 1993-1-1:2005 (EN 1993)

The EN 1993 version of Eurocode 3, Design of steel structures, Part 1.1 Generalrules and rules for buildings (EN 1993) provides design rules applicable tostructural steel used in buildings and civil engineering works. It is based on the

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ultimate limit states philosophy that is common to modern standards. Theobjective of this method of design is to ensure that possibility of failure is reducedto a negligible level. This is achieved through application of safety factors to boththe applied loads and the material properties.

The code also provides guidelines on the global methods of analysis to be used forcalculating internal member forces and moments. STAAD uses the elastic methodof analysis which may be used in all cases. Also there are three types of framingreferred to in EC3. These are “Simple”, “Continuous”, and “Semi-continuous”which reflect the ability of the joints to developing moments under a specificloading condition. In STAAD only “Simple” and “Continuous” joint types can beassumed when carrying out global analysis.

National Annex Documents

Various authorities of the CEN member countries have prepared National AnnexDocuments to be used with EC3. These documents provide alternative factors forloads and may also provide supplements to the rules in EC3.

The current version of EC3 (EN 1993)implemented in STAAD adheres to thefactors and rules provided in EN 1993-1-1:2005. The current version ofSTAAD.Pro includes the following National Annexes viz.

a. British National Annex [NA to BS EN 1993-1-1:2005]

b. The Dutch National Annex [NEN-EN 1993-1-1/NB] and

c. Norwegian National Annex [NS-EN 1993-1-1:2005/NA2008]

d. French National Annex [Annexe Nationale a la NF EN 1993-1-1:2005]

e. Finnish National Annex [SFS EN 1993-1-1:2005]

f. Polish National Annex [PN EN 1993-1-1:2005]

g. Singaporean National Annex [SS EN 1993-1-1:2005]

h. Belgian National Annex [NBN EN 1993-1-1:2005]

The choice of a particular National Annex is based on the value of a new NAparameter that is set by the user when specifying the EN 1993 version of Eurocode3. Please refer to section 5B.6 (B) for a description of the NA parameter.

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Axes convention in STAAD and EC3By default, STAAD defines the major axis of the cross-section as Z-Z and the minoraxis as Y-Y. A special case where Z-Z is the minor axis and Y-Y is the major axis isavailable if the SET Z UP command is used and is discussed in Section 5.5 of theTechnical Reference Manual. The longitudinal axis of the member is defined as Xand joins the start joint of the member to the end with the same positive direction.

EC3, however, defines the principal cross-section axes in reverse to that of STAAD,but the longitudinal axis is defined in the same way. Both of these axes definitionsfollow the orthogonal right hand rule. See figure below.

Bear this difference in mind when examining the code-check output from STAAD.

Figure 5.3 - Axis convention in STAAD and EC3

5B.2 (B)   Analysis Methodology

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loading specificationsand using appropriate load factors to create necessary loading situations.

5B.3 (B) Material Properties and Load Factors  

The characteristic yield strength of steel used in EC3 (EN 1993) design is based ontable 3.1 of the code.  Design resistances are obtained by dividing the characteristicvalue of a particular resistance by the global partial safety factor for the resistance,Γm. The magnitude of Γm is based on Cl. 6.1 of EN 1993-1-1:2005 and can changedepending on the selected National Annex.

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Material coefficients for steel in STAAD take the following default values unlessreplaced by user’s numerical values provided in the input file.

Modulus of Elasticity, E = 205000 N/mm2

Shear Modulus, G = E/2(1+ ν)

Poisson’s Ratio, ν = 0.3 

Unit weight, Γ = 76.8 KN/m3

The magnitude of design loads is dependent on Γf, the partial safety factor for the

action under consideration. In STAAD the user is allowed total control in providingapplicable values for the factors and their use in various load combinations.

5B.4 (B) Section Classification  

The occurrence of local buckling of the compression elements of a cross-sectionprevents the development of full section capacity. It is therefore imperative toestablish this possibility prior to determining the section capacities. Cross sectionsare classified in accordance with their geometrical properties and the stress patternon the compression elements. For each load case considered in the designprocess, STAAD determines the section class and calculates the capacitiesaccordingly.

The EC3 (EN 1993) design module in STAAD can design members with all sectionprofiles that are of Class 1, 2, or 3 as defined in section 5.5 of the code. However,the design of members that have a Class 4 section profile are limited to:

l wide flange

l tee

l single channel

l single angle

l rectangular hollow sections

l circular hollow sections

Also built-up user sections that are class 4 sections are not dealt with in the currentversion of EC3 design in STAAD.Pro.

The design of laced and battened members is not considered in the current versionof EC3 (EN 1993) design module in STAAD.Pro.

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5B.5 (B) Member Design  

EN 1993-1-1:2005, together with any specified National Annex, is used for codecheck or selection of all cross sections and shapes listed in Section 5B.4 (B).However, where EN 1993 or the National Annex has not specified a method orvalues for a specific clause or parameter, STAAD.Pro uses Non-ContradictoryComplimentary Information (NCCI) documents as explained in the followingcorresponding sections.

The design philosophy and procedural logistics are based on the principles ofelastic analysis and ultimate limit state design. Two major failure modes arerecognized:

l failure by overstressing

l failure by stability considerations

The following sections describe the salient features of the design approach.Members are proportioned to resist the design loads without exceeding thecharacteristic stresses or capacities. Member selection is done on the basis ofselecting the most economic section on the basis of the least weight criteria. It isgenerally assumed that you (the engineer) will take care of the detailingrequirements, such as the provision of stiffeners, and check the local effects likeflange buckling, web crippling, etc.

Note: The design of class 4 (slender) sections is limited to WIDE FLANGE, TEE,SINGLE CHANNEL, SINGLE ANGLE, and RECTANGULAR & CIRCULAR HOLLOWSECTIONS. The effective section properties are evaluated as described in Cl.6.2.2.5 of the code.

You are allowed complete control over the design process through the use of theparameters listed in Table 5B.3. Default values of parameters will yield reasonableresults in most circumstances. However, you should control the design and verifyresults through the use of the design parameters.

5B.5(B).1 Members Subject to Axial Loads

The cross section capacity of tension only members is checked for ultimate limitstate as given in Cl. 6.2.3 of the code.

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Compression members will be checked for axial capacity of the cross section inaddition to lateral buckling/stability. The cross section capacity will be checked asgiven in section 6.2.4 of the code.

Lateral stability of a pure compression member will be checked as per the methodgiven in Cl. 6.3 of the code. The compression member stability will be verified as:

Where Nb,Rd

is the design buckling resistance given by:

for Class 1, 2, or 3 cross-sections

for Class 4 cross-sections

Where:

χ is the reduction factor as given in section 6.3.12 of the code. The buckling curvesused to evaluate the reduction factor are selected from Table 6.2 of the code basedon the cross section type and the steel grade.

Note: Only the five grades of steel given in table 6.2 will be used whenselecting the buckling curve. The steel grade used for this selection is based onthe SGR design input parameter (See Section 5B.(6)B). Even if you havespecified a custom yield strength (using the PY parameter), the choice of abuckling curve will be based on the value of SGR parameter.

Compression members that are susceptible to torsional or torsional flexuralbuckling are checked for these modes of failure as well. The non-dimensionalslenderness ¯λ

Tfor these members is evaluated per Cl. 6.3.1.4 of the EN 1993

code. The maximum slenderness among the flexural buckling slenderness,torsional slenderness, and torsional-flexural slenderness is used to evaluate thereduction factor, χ, for such members. The elastic torsional buckling load, N

cr,T,

and the elastic torsional-flexural buckling load, Ncr,TF

, are evaluated based on themethod given in the NCCI “SN001a-EN-EU: Critical axial load for torsional andflexural torsional buckling modes” (unless otherwise specified by a particularNational Annex).

EN 1993-1-1:2005 does not specifically deal with single angle, double angles,double channels, or Tee sections and does not provide a method to work out the

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slenderness of such members. In these cases, the EC3 (EN 1993) design module ofSTAAD.Pro uses the methods specified in BS 5950-1:2000 to calculate theslenderness of these members. Cl. 4.7.10 and Table 25 of BS 5950-1:2000 areused in the current version of the Eurocode 3 design module.

Single Angle SectionsAngle sections are un-symmetrical and when using BS 5950:2000 table 25, fouraxes must be considered; two principal ( u-u and v-v) and two geometric (a-a andb-b). The effective length for the v-v axis, Lvv, is taken as the LVV parameter or LY ·KY, if not specified.  The a-a and b-b axes are determined by which leg of the angleis fixed by the connection and should be specified using the LEG parameter, seesection 5B.6 (B) for more information on the LEG parameter. The effective length inthe a-a axis is taken as LY · KY and the effective length in the b-b axis as LZ · KZ.

The following diagram shows the axes for angles which have been defined witheither an ST or RA specification and is connected by its longer leg (i.e., a-a axis isparallel to the longer leg).

Figure 5.4 - Axis orientation for single angles

ST angle and USER table angles RA angle

5B.5(B).2 Members Subject to Bending Moments

The cross section capacity of a member subject to bending is checked as per Cl.6.2.5 of the code. The condition to be satisfied is:

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Where Mc,Rd

is the is the design resistance given by:

for class 1 and 2 cross-sections

for class 3 cross-sections

for class 4 cross-sections

Cross sectional bending capacity checks will be done for both major and minoraxis bending moments.

Members subject to major axis bending will also be checked for Lateral TorsionalBuckling resistance as per Section 6.3.2 of the code. The design bucklingresistance moment M

b,Rdwill be calculated as:

Where:

χLTis the reduction factor for lateral torsional buckling. This reduction

factor is evaluated per Cl. 6.3.2.2 or Cl 6.3.2.3 of the EN 1993 codedepending on the section type. For I sections, the program will bydefault use Cl. 6.3.2.3 to evalute χ

LTand for all other sections the

program will resort to Cl 6.3.2.2. However, if a particular NationalAnnex has been specified, the program will check if the National Annexexpands on Cl.6.3.2.3 (Table 6.5) to include sections other than Isections. If so, the program will use Cl. 6.3.2.3 for the cross-section(s)included in Cl. 6.2.2.3 (or Table 6.5). For all other cases the programwill use Cl. 6.3.2.2.

Note: You have the option to choose the clause to be used tocalculate χ

LTthrough the MTH design parameter. Setting MTH to 0

(default value) will cause the program to choose Cl.6.3.2.3 for ISections and Cl 6.2.3.2 for all other section types. As mentionedabove, if the National Annex expands on Cl. 6.3.2.3 to include

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sections other than I Sections, the program will use Cl. 6.3.2.3 bydefault.

The non-dimensional slenderness λLT(used to evaluate χ

LT) for both the above

cases is evaluated as:

Where:

Mcris the elastic critical moment for lateral torsional buckling. EN 1993-

1-1 does not however specify a method to work out Mcr. Hence, the

program will make use of the method specified in Annex F of DD ENV1993-1-1 to work out M

crby default.

Note: The method specified in Annex F will be used only when theraw EN 1993-1-1:2005 code is used without any National Annex. Ifa National Annex has been specified, the calculation of M

cr(and λ

LT)

will be done based on the specific National Annex. (See "5B.(C)European Codes - National Annexes to Eurocode 3 [EN 1993-1-1:2005]" on page 343 for specific details). If the National Annexdoes not specify a particular method or specify a referencedocument, the program will use the NCCI document SN-003a-EN-EU for doubly symmetric sections and SN030a-EN-EU for mono-symmetric sections that are symmetric about their weak axis. For allother sections types the program will use Annex F of DD ENV 1993-1-1 to calculate Mcr.

5B.5(B).3 Members Subject to Shear

The cross section capacity of a member subject to shear is checked as per Cl. 6.2.6of the code. The condition to be satisfied is:

Where:

Vc,Rd

is the is the shear design resistance given by:

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Av is the shear area and is worked out for the various section types asgiven in Cl. 6.2.6(3) of the code.

5B.5(B).4 Members Subject to Torsion

Note: This feature requires STAAD.Pro V8i (SELECTseries 2) build 2007.07 orlater.

GeneralEurocode 3 (EN 1993-1-1:2005) gives very limited guidance for the analysis anddesign of torsion members. While both elastic and plastic analyses are permittedgenerally, the design analysis methods for torsion discussed within EC3 areprimarily based on elastic methods. Also, only the first yield design resistance isspecifically discussed for torsion members. Furthermore, there is no guidance onsection classification nor on how to allow for the effects of local buckling on thedesign resistance for combined torsional effects. EC3 also does not specificallydeal with members subject to combined bending and torsion and loosely statesthat the yield criteria (Eqn 6.1 in the code) can be used for elastic verification.

The method used by STAAD.Pro is therefore based on the SCI publication “P057:Design of members subject to combined bending and torsion”. Though thispublication is based on the British standard BS 5950-1, the principles from thisdocument are applied in the context of Eurocode 3.

Note: At the time this feature has been implemented in STAAD.Pro, SCI are inthe process of updating document P057 to be in accordance with Eurocode 3.Hence this method might be subject to modifications subject to the publicationof a newer version of P057. The NCCI document “SN007b-EN-EU: Torsion”will also be referenced where appropriate.

Code BasisTorsion design in EC3 is given in Cl. 6.2.7 of EN 1993-1-1:2005. Therefore, thisclause is used primarily for this implementation.

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EN 1993-1-1:2005 does not deal with members subject to the combined effects oftorsion and lateral torsional buckling. However, EN 1993-1-6 considers such acondition in Appendix A. Therefore, STAAD.pro uses Appendix A of EN 1993-1-6to check for members subject to combined torsion and LTB.

The following clauses from EC3 are then considered:

l Cl. 6.2.7(1)

l Cl. 6.2.7(9)

l Cl. 6.2.7(5)

l EC-3 -6 App A

Note: STAAD.Pro does, however, use this clause (6.2.7) to report the outputfor all torsion checks. Also any distortional deformations and any amplificationin the torsional or shear stresses due to distortions will be neglected by theprogram.

l Clause 6.2.7(1)

States that for members subject to torsion, the design torsional moment TEd

at each cross section should satisfy:

TEd/ R

Rd≤ 1.0

Where:

TRdis the design torsional resistance of the cross section.

This is the primary condition that will need to be satisfied for memberssubject to torsion. The method for working out the torsional resistance T

Rd,

for the various cases is dealt in the following sections.

l Cl. 6.2.7(9)

States that:

For combined shear force and torsional moment, the plastic shearresistance accounting for torsional effects should be reduced from

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Vpl,Rd

to Vpl,T,Rd

and the design shear force should satisfy:

VEd/ V

pl,T,Rd≤ 1.0

The code also gives means to evaluate Vpl,T,Rd

in equations 6.26 to 6.28.These equations, however, only deal with I/H sections, Channel sections,and structural hollow sections (RHS, SHS, CHS). Therefore, the applicationof Cl. 6.2.7(9) is only performed for these section profiles.

l Cl 6.2.7(5)

States that the yield criteria given in Cl. 6.2.1(5) of EN 1993-1-1:2005 maybe used for elastic verification. STAAD.Pro evaluates the stresses due to thevarious actions on the cross section and applies this yield criterion.

The program allows for two types of checks for members subject to torsion forEC3 design:

I. Basic Stress Check: This method is intended to be a simplified stress checkfor torsional effects. This method will produce the output corresponding toCl. 6.2.7(5) of EN 1993-1-1.

II. Detailed Checks: This method will perform a full torsional analysis of themember. All four of the clause checks mentioned earlier will be performed.

The details of these checks are as described below.

You have the option to choose the method to be used for a specific member orgroup of members. This will be facilitated by setting the value of the TORSIONdesign parameter to one of the following values:

TORSION value

Description

0 (Default) Include basic stresschecks, only if member is subject totorsion.

1 Include torsion (Basic stress checkexcluding warping effects).

2 Include torsion (Detailed checksincluding warping effects).

3 Ignore all torsion checks

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The TORSION parameter will have a value of zero (0) by default. This will cause theprogram to trigger the torsion checks only if the member is subject to torsionalmoments. For this default setting, the program will ignore torsion checks if there isno torsional moment in the member. Setting the value of the TORSION parameter tothree (3) will cause the program to ignore all torsional moments. The detailedoutput (i.e., TRACK 2) will indicate that torsion has been ignored for that particularmember. The details of setting the values to one (1) or two (2) and thecorresponding checks performed are as described below.

Note: If the TORSION parameter is set to 1 or 2, the program will perform theappropriate checks even if the member is not subject to torsional moments. Insuch cases, the program will perform the checks with a value of zero for thetorsional moment.

5B.5(B).4.1 Basic stress checkThis method is used when the TORSION parameter is specified as one (1).

This method is intended to be a simplified stress check for torsional effects per Cl.6.2.7(5). Any warping stresses that may develop due to the end conditions will beignored for this option. The program will consider the forces (including torsion) atvarious sections along the length of the member and for each section, will calculatethe resultant stress (Von Mieses) at various points on the cross section. Thelocation and number of points checked for a cross section will depend on the crosssection type and will be as described below.

The stress check will be performed using equation 6.1 of EN 1993-1-1:2005 asgiven below:

Where:

σx,Ed

is the longitudinal stress

σz,Ed

is the transverse stress and

τEdis the resultant shear stress.

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Note: Since transverse stresses are very small under normal loadingconditions (excluding hydrostatic forces), the term will be negligible and henceis taken as zero.

σx,Ed

= σx+ σ

bz+ σ

by= F

x/Ax+ M

z/Zz+ M

y/Zy

τEd= T/J · t + V

y·Q/(I

z·t) + V

z·Q/(I

y*t)

Where:

T is the torsion at the particular section along the length of the member

J is the torsion constant

t is the thickness of the web/flange

V is the shear force

Q is the statical moment about the relevant axis

I is the second moment of area about the relevant axis

The stress check as per equation 6.1 is performed at various stress points of across section as shown in figures below:

Shape Section Sketch

Doubly sym-metric wideflange profile

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Shape Section Sketch

Pipe profiles

Tube profiles

α = tan-1(M

z/M

y)

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Shape Section Sketch

Channel profiles

The resultant ratio will be reported under Cl. 6.2.7(5) in the detailed designoutput.

5B.5(B).4.2 Detailed stress checkThis method is used when the TORSION parameter is specified as two (2).

This method performs a detailed torsional analysis of a member depending on thetorsion loading conditions and the support conditions at the member ends. Thismethod is based on the SCI publication P057 and includes any warping stresses(direct warping stresses and warping shear stresses) depending on the endconditions of the member. This implementation considers seven different cases ofloading and end conditions as given in publication P057 – Section 6. Theloading/end conditions for a member are specified by the use of the CMT designparameter (refer to Table 5B1.5(B) for parameter values and descriptions).

All the equations used to evaluate the torsional moments and associated stressesare as given in Appendix B of P057. The resultant stresses are evaluated at varioussections along the length of the member and the following checks will beperformed:

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Clause 6.2.7(1) – Torsional resistance of the sec-tion.

In general, the torsion at any section TEdis resolved into two components, viz.

The pure torsional (St. Venant’s) moment (Tt,Ed) and

The warping torsional moment(Tw,Ed

)

Therefore,

TEd= T

t,Ed+ T

w,Ed= GJφ’ = EHφ’’’

[Ref SCI pub. P057]

Where:

φ’ and φ’’’ are the first and third derivates of twist (φ ), respectively, anddepend on the end conditions and loading. These are evaluated fromthe equations in Annex B of P057 and are based the specified CMTparameter.

Note: Although the equation given the NCCI document SN007b-EN-EU can beused to evaluate T

wrd, the NCCI does not give the eqn. to evaluate φ’’’.

Therefore, Annex B of P057 is used.

The torsional resistance of the section is also considered as the sum of the puretorsion resistance and the warping torsion resistance. The pure torsion resistance(Tt,Rd) and the warping torsional resistance (T

w,Rd) are evaluated as:

For closed sections:

Tt,Rd

= 2 · Ac· t · τ

max

Where:

Acis the area enclosed by the mean perimeter

t is the max thickness

τmax

is the max. allowable shear stress = (fy/√3)/ Γm0

For open sections (I & channel):

Tt,Rd

= τmax

· J / t

Where:

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J is the torsion const

t is the max thickness.

Tw,Rd

= (fy/ Γ

m0)· t · b2 / 6

Where:

b is the width of the section

t is the thickness of the flange for I- sections; minimum of flange orweb thickness channel sections

The check according to Cl 6.2.7(1) will then be performed to ensure that thefollowing conditions are satisfied:

Tt,Ed

/ Tt,Rd

≤ 1

Tw,Ed

/ Tw,Rd

≤ 1

TEd/ T

Rd≤ 1

Clause 6.2.7(9) – Plastic shear resistance due totorsion.

STAAD.Pro checks for shear resistance of a section based on Cl. 6.2.6 for EC3 andthe plastic shear resistance (in the absence of torsion) is evaluated as:

Where:

Avis as pre Cl.6.2.6 (3) for the various sections

When torsion is present, along with the shear force, the design shear resistancewill be reduced to V

pl,T,Rd, where V

pl,T,Rdis evaluated as follows:

i. For I or H Sections:

ii. For Channel Sections:

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iii. For Structural Hollow Sections:

Where

τt,Ed

is the shear stress due to direct (St. Venant’s) torsion and

τw,Ed

is the shear stress due to warping torsion.

The various shear stresses due to torsion τt,Ed

and τw,Ed

are evaluated as follows:

i. For Closed sections:

The shear stresses due to warping can be ignored as they will be insignificantand hence:

τt,Ed

= TEd/(2·A

c·t)

[Ref NCCI Sn007b-EN-EU]

Where:

TEdis the applied torsion,

Acis the area delimited by the mean perimeter and

t is the thickness of the cross section

τw,Ed

= 0, since warping is ignored

ii. For Open sections [I, H, Channel] sections:

For I and H sections, the web will not be subject to warping stresses andtherefore warping shear can be ignored (τ

w,Ed=0).

The stress due to pure torsion is evaluated as:

τt,Ed

= G·t·φ’

[Ref SCI pub. P057]

Where:

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G is the shear modulus

φ’ is a function depending on the end condition and loading(T).This will be taken from section 6 and Annex B of P057.

Note: Although the maximum stress is at the thickest section of theprofile, the program uses the web thickness for this clause (since theshear capacity is based on the web area) unless the load is parallel to theflanges, in which case the flange thickness is used.

For channel sections that are free to warp at the supports and, thus, are notsubject to warping stresses:

The warping shear stress is evaluated as:

τw,Ed

= E·Sw·φ’’’ / t

[Ref SCI pub. P057]

Where:

E is the elastic modulus,

Swis the warping statistical moment and

φ’ is a function depending on the end condition and loading(T).This will be taken from section 6 and Annex B of P057.

t is the thickness of the element.

Clause 6.2.7(5) – Check for elastic verification ofyield

Eurocode 3 gives yield criterion as per eqn. 6.1 and STAAD.Pro uses the yieldcriterion given in EC-3. When a member is subject to combined bending andtorsion, some degree of interaction occurs between the two effects. The angle oftwist caused by torsion is amplified by the bending moments and will induceadditional warping moments and torsional shears. Account must also be taken ofthe additional minor axis moments produced by the major axis moments actingthrough the torsional deformations, including the amplifications mentionedearlier.

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For members subject to bending and torsion, the stresses are evaluated as follows:

Direct bending stress (major axis): σbz= M

z/ Z

z

Direct bending stress (minor axis): σby= M

y/ Z

y

Direct stress due to warping: σw = E·Wns· φ’’

Direct stress due to twist (min. axis): σbyt

= Myt/ Z

y

Direct stress due to axial load (if any): σc= P/ A

Where:

Mzis the major axis moment & My is the minor axis moment.

φ’’ is the differential function based on twist (ref P057 Annex B. & Table6)

Wnsis the normalized warping function.

Myt= φ·M

z(see Appendix B of P057 to evaluate φ)

Shear stresses due to torsion and/or warping is evaluated as described above forClause 6.2.7(9).

Check for yield (capacity checks) is then done according to Eqn 6.1 of EN 1993-1-1:2005, as described for the Basic Stress Check (TORSION = 1):

Clause EC-3:6 App A – Check for combined Torsionand Lateral Torsional buckling

The interaction check due to the combined effects of bending (including lateraltorsional buckling) and torsion will be checked using Annex A of EN 1993-1-6:2007. Note that this interaction equation does not include the effects of any axialload.

Warning: At present, SCI advises that no significant work has been publishedfor this case and work is still ongoing. So at present is advisable not to allow fortorsion in a member with large axial load.

Members subject to combined bending and torsion will be checked to satisfy:

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Where:

Cmzis the equivalent uniform moment factor for bending about the z-z

axis, according to EN 1993-1-1 Table B.3.

My,Ed

and Mz,Ed

are the design values of the maximummoment aboutthe y-y and z-z axis, respectively.

My,Rk

and Mz,Rk

are the characteristic values of the resistance momentof the cross-section about it y-y and z-z axis, respectively, from EN1993-1-1, Table 6.7.

My,cr

is the elastic critical lateral-torsional buckling moment about they-y axis.

Tw,Ed

is the design value of the warping torsional moment.

Tw,Rk

is the characteristic value of the warping torsional resistancemoment.

χLTis the reduction factor for lateral torsional buckling according to

6.3.2 of EN 1993-1-1.

Note: For all of the above checks the effective length of the member to beused for torsion can be set by using the EFT design parameter.

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5B.5(B).5 Members Subject to Combined Forces

Members subject to Bending and AxialForceWhen a member is subject to a combined axial load and a bending moment, theprogram evaluates a reduced moment capacity based on Cl. 6.2.9 of the code. ForClass 1, 2, and 3 sections, the program evaluates the reduced moment from theequations given in Cl. 6.2.9.1 of the code. For class 4 sections, the interactionequation given by equation 6.44 are checked.

In the case of members subject to axial load and biaxial bending, the program willconsider the interaction equation 6.41 of the code.

Note: By default, the program will use the values of the constants ‘α’ and ‘β’ asgiven in the code for the different sections types. However, you can overridethese values using the ALPHA and BETA design parameters (See Section5B.6(B)).

Note: The program uses the parameter ELB (See Section 5B.6(B)) to overridethe Cl.6.2.9 checks for combined axial load and bending case. When specfied as1, the program uses the more general equation 6.2 of EN 1993-1-1, instead.

Members subject to Bending, Shear, andAxial ForceWhen a member is subject to a combined axial load, shear force, and a bendingmoment, the program evaluates the reduced yield strength as given in Cl 6.2.10 (3)of the code. The reduction in the yield strength is done only when the applied shearforce exceeds 50% of the design shear resistance V

pl,Rd. This reduced yield

strength is then used to evaluate the reduced moment capacity of the section.

Members subject to Bending and AxialCompressionThe bending resistance of members could be reduced by the presence of a co-existent axial load. This is then checked against the lateral-torsional buckling

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resistance of the section. The EN 1993 design module in STAAD takes such ascenario into account and performs the necessary checks as per Cl. 6.3.3 of thecode.

Generally, EC3 requires checking cross-section resistance for local capacity andalso checking the overall buckling capacity of the member. In the case of memberssubject to axial tension and bending, there is provision to take the stabilizing effectof the tension load into consideration. This is achieved by modifying the extremecompression fibre stress and calculating an effective applied moment for thesection. The checks are done as per Cl. 6.2.9 of the code. In case of a combinedaxial compressive load and bending moment, the member is checked per the rulesin section 6.3.3 of the code. The program checks to ensure that both theinteraction equations 6.61 and 6.62 of the code are satisfied. The interactionfactors kzz, kyy, kzy & kyz will be evaluated using Annex B of EN 1993-1-1 bydefault. Hence for the EN 1993-1-1 code in STAAD.Pro (without NationalAnnexes), uses Annex B. The choice between using Annex A and Annex B will bebased on the choice specified by a particular National Annex, if used. If theNational Annex itself gives a choice between Annex A and Annex B, the programuses Annex B to evaluate the interaction factors.

Note: EN 1993-1-1:2005 does not specifically deal with single angle, doubleangles, double channels or Tee sections and does give a method to work outthe slenderness of such members. In these cases, the Eurocode 3 (EN 1993-1-1) design module of STAAD.Pro uses the methods specified in BS 5950-1:2000to calculate the slenderness of these members. Cl. 4.7.10 of BS 5950-1:2000 isused in the current version of the EC3 design module. Please refer to Section5B.5.2 for ST and RA angle specifications.

Note: Laced or battened compression members are not dealt within thecurrent version of EC3 (EN 1993) design module in STAAD.Pro.

5B.6(B) Design Parameters

Design parameters communicate specific design decisions to the program. Theyare set to default values to begin with and may be altered to suite the particularstructure.

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Depending on the model being designed, you may have to change some or all ofthe parameter default values. Some parameters are unit dependent and whenaltered, the n setting must be compatible with the active “unit” specification.

Table 5B.1 (B) lists all the relevant EC3 parameters together with description anddefault values.

ParameterName

DefaultValue

Description

CODE - Must be specified as EN 1993-1-1:2005 to invoke design perEurocode 3:2005 (EN 1993).

Design Code to follow.

See section 5.48.1 of the Technical

Reference Manual.

ALH 0.5 The ratio of the distance of the

point torque (from the start of the

member) to the length of the

member. The default value of 0.5

represents torque acting at the

mid-span of a symmetrically

loaded member. Values can range

from 0 to 1.

ALPHA 1.0 Used to input a user defined value

for the α factor in equation 6.41

for combined bending and axial

force checks.

BEAM 3 Parameter to control the number

of sections to checked along the

length of a beam:

0. Check sections with end

Table 5B.4 - Steel Design Parameters EC3 EN

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ParameterName

DefaultValue

Description

forces only

1. Check at location of max-

imum Mz along beam

2. Check sections with end

forces and forces at location

of BEAM 1.0 check.

3. Check at every 1/13th point

along the beam and report

the maximum

BETA 1.0 Used to input a user defined value

for the β factor in equation 6.41

for combined bending and axial

force checks.

C1 1.132 Corresponds to the C1 factor to be

used to calculate Elastic critical

moment Mcras per Clause 6.3.2.2

C2 0.459 Corresponds to the C2 factor to be

used to calculate Elastic critical

moment Mcras per Clause 6.3.2.2

C3 0 Corresponds to the C3 factor to be

used to calculate Elastic critical

moment Mcras per Clause 6.3.2.2

CAN 0 Member will be considered as a

cantilever type member for

deflection checks.

0 indicates that

member will not be

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ParameterName

DefaultValue

Description

treated as a cantilever

member

1 indicates that the

member will be treated

as a cantilever member

CMM 1.0 Indicates type of loading and

support conditions on member.

Can take a value from 1 to 8.

Refer to Table 5B1.4(B) for more

information on its use.

CMN 1.0 Indicates the level of End-

Restraint.

1.0 = No fixity

0.5 = Full fixity   

0.7 = One end free and

other end fixed

CMT 1 Used to indicate the loading and

support condition for torsion.

Can take a value of 1-7.

Refer to table 5B1.5(B) for more

information

DFF None

(Mandatory

for

deflection

"Deflection Length" / Maxm.

allowable local deflection

See Note 1d below.

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ParameterName

DefaultValue

Description

check,

TRACK

4.0)

DJ1 Start Joint

of member

Joint No. denoting starting point

for calculation of "Deflection

Length" . See Note 1 below.

DJ2 End Joint

of member

Joint No. denoting end point for

calculation of "Deflection Length".

See Note 1 below.

DMAX 100.0 cm Maximum allowable depth for the

member.

DMIN 0 Minimum required depth for the

member.

EFT Member

Length

Effective length for torsion. A

value of 0 defaults to the member

length.

ELB 0 Used to specify the method for

combined axial load + bending

checks

0. Uses Cl. 6.2.9 of EN 1993-1-

1:2005

1. Uses Cl. 6.2.1(7) - Eqn. 6.2

of EN 1993-1-1:2005

ESTIFF 0 (For use with the Dutch NA only)

Method for checking columns

forming part of (non)/buttressed

framework:

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ParameterName

DefaultValue

Description

0. Checks per Cl 12.3.1.2.3 of

NEN 6770: Section 1

1. Checks per Cl 12.3.1.2.3 of

NEN 6770: Section 2

FU 0 Ultimate tensile strength of steel.

GM0 1.1 Corresponds to the Γm0factor in

EN 1993-1-1:2005

GM1 1.1 Corresponds to the Γm1factor in

EN 1993-1-1:2005

GM2 1.1 Corresponds to the Γm2factor in

EN 1993-1-1:2005

GST 0 Used to specify the section type to

be used for designing a “General

Section” from the user table. The

member will be considered as the

specified type with the user

defined properties. The available

options and corresponding values

are as below:

0. I-Section

1. Single Channel

2. Rectangular Hollow Section

3. Circular Hollow Section

4. Angle Section

5. Tee Section

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ParameterName

DefaultValue

Description

Note: This parameter will beignored if it has been assigned

to any section other than a

General Section.

KC 1.0 Corresponds to the correction fac-

tor as per Table 6.6 of EN 1993-1-

1:2005. Program will calculate kc

automatically if this parameter is

set to 0.

KY 1.0 K factor in local y axis.

KZ 1.0 K factor in local z axis.

LEG 0 Slenderness values for angles as

determined from BS 5950-2000

Table 25.

See "2B.6 Design Parameters" on

page 90

LVV Max. value

of Lyy

Leg length for Lvv (length about v-

v- aces of single angle section), as

per Lyy. Used for slenderness cal-

culations.

LY Member

Length

Compression length in local y axis,

Slenderness ratio =

(KY)*(LY)/(Ryy)

LZ Member

Length

Compression length in local z axis,

Slenderness ratio =

(KZ)*(LZ)/(Rzz)

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ParameterName

DefaultValue

Description

MU 0 To be used with CMM values of 7and 8. See Table 5B1.4(B).

Currently valid only with the

French NA.

MTH 0 Used to select the clause to be

used to calculate the LTB reduction

factor, χLT. The available options

and corresponding values are as

below:

0. Use default method based on

section type (default)

1. Use Cl.6.3.2.2

2. Use Cl.6.3.2.3

By default, the program will use Cl

6.3.2.3 for rolled & built-up I-

sections and Cl. 6.3.2.2 for all

other sections. If, however, the

specified National Annex expands

on Cl. 6.3.2.3 to include other

section types (e.g., the UK NA),

the program will use Cl. 6.3.2.3 by

default for that particular section

type.

See "5B.(C) European Codes -

National Annexes to Eurocode 3

[EN 1993-1-1:2005]" on page 343

for additional details on

NA documents.

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ParameterName

DefaultValue

Description

NA 0 Choice of National Annex to be

used for EC3 design.

(see 5B1.2(B) for more

information)

NSF 1.0 Net tension factor for tension

capacity calculation.

PLG 0 To be used to determine whether

to include the additional

interaction checks as per CL.

NA.20(2) and NA.20(3) of the

Polish National Annex.

Note: This parameter will beapplicable only to the Polish

NA

PY Yield

Strength

The yield strength default value is

set based on the default value of

the SGR parameter.

RATIO 1 Permissible ratio of loading to

capacity.

SBLT 0.0 Indicates if the section is rolled or

built-up.

0.0 = Rolled

1.0 = Built-up    

SGR 0 Steel grade as in table 3.1 of EN

1993-1-1:2005

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ParameterName

DefaultValue

Description

0.0 - indicates S 235

grade steel

1.0 - indicates S 275

grade steel

2.0 - indicates S 355

grade steel

3.0 - indicates S 420

grade steel

4.0 - indicates S 460

grade steel

Note: As EN 1993-1-1:2005does not provide a buckling

curve in table 6.2 for grade S

450 steel (in Table 3.1 of EN

1993-1-1:2005), the program

will use the same buckling

curves as for grade S 460 when

calculating the buckling

resistance as per clause 6.3.

STIFF Member

Length or

depth of

beam,

whichever

is greater

Distance between transverse stiff-

ener plates, used to prevent web

shear buckling. If not specified or

if a value of 0 is provided, the pro-

gram will assume the web is unstiff-

ened.

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ParameterName

DefaultValue

Description

TOM 0 Total torsion for design used for

torsion checks.

TORSION 0 Method to be used for a specific

member or group of members:

0. Perform basic torsion checks

if member is subject to

torsion.

1. Perform basic stress check

(Ignore warping effects).

2. Perform detailed checks

(including warping effects).

3. Ignore all torsion checks

Note: For options 1 or 2, theprogram will perform the

torsion related checked even if

torsional moment is absent and

will use a value of zero for the

torsional moment.

TRACK 0 Specify level of detail in output.

0. Summary of results only.

1. Summary with member

capacities.

2. Detailed results.

3. Deflection check results.

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ParameterName

DefaultValue

Description

UNF 1 Unsupported length as a fraction

of the actual member length.

UNL Member

Length

Unrestraint length of member used

in calculating the lateral-torsional

resistance moment of the member.

ZG +Section

Depth/2

Distance of transverse load from

shear center. Used to calculate Mcr.

Note: For Tee sections, ZGwill have a default value of

(+Flange thickness/2)

Notes:

1. CAN, DJ1, and DJ2 – Deflection

a. When performing the deflection check, you can choose between twomethods. The first method, defined by a value 0 for the CAN parameter,is based on the local displacement. Local displacement is described inSection 5.44 of the Technical Reference Manual.

If the CAN parameter is set to 1, the check will be based on cantileverstyle deflection. Let (DX1, DY1, DZ1) represent the nodal displacements(in global axes) at the node defined by DJ1 (or in the absence of DJ1,the start node of the member). Similarly, (DX2, DY2, DZ2) represent thedeflection values at DJ2 or the end node of the member.

Compute Delta = SQRT((DX2 - DX1)2 + (DY2 - DY1)2 + (DZ2 - DZ1)2)

Compute Length = distance between DJ1 & DJ2 or, between start nodeand end node, as the case may be.

Then, if CAN is specified a value 1, dff = L/Delta

Ratio due to deflection = DFF/dff

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b. If CAN = 0, deflection length is defined as the length that is used forcalculation of local deflections within a member. It may be noted thatfor most cases the “Deflection Length” will be equal to the length of themember. However, in some situations, the “Deflection Length” may bedifferent. A straight line joining DJ1 and DJ2 is used as the referenceline from which local deflections are measured.

For example, refer to the figure below where a beam has beenmodeled using four joints and three members. The “Deflection Length”for all three members will be equal to the total length of the beam inthis case. The parameters DJ1 and DJ2 should be used to model thissituation. Thus, for all three members here, DJ1 should be 1 and DJ2should be 4.

D = Maximum local deflection for members 1, 2, and 3.

PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

c. If DJ1 and DJ2 are not used, "Deflection Length" will default to themember length and local deflections will be measured from originalmember line.

d. It is important to note that unless a DFF value is specified, STAAD willnot perform a deflection check. This is in accordance with the fact thatthere is no default value for DFF (see Table 2B.1).

e. The above parameters may be used in conjunction with other availableparameters for steel design.

2. NA Parameter

The values for NA parameter are as follows:

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NA Value Country

0 Uses the base EN 1993-1-1:2005 code. Thedefault values specified in En 1993-1-1:2005will be used for the partial safety factors andvarious parameter values where applicable(default).

1 United Kingdom (British NA) — Uses the BSEN 1993-1-1:2005 version of Eurocode 3along with the UK National Annex.

2 Netherlands (Dutch NA) — Uses the NEN EN1993-1-1:2005 version of the code.

The Dutch National Annex [NEN-EN 1993-1-1/NB] has been added in this module. Pleasenote that the Dutch National requiresadditional checks as per NEN 6770 and NEN6771 which will also be performed duringdesign checks with this parameter value

3 Norway (Norwegian NA) — Uses the NS-EN1993-1-1:2005 version of the code. The Nor-wegian National Annexe [ NS-EN 1993-1-1:2005/Na 2008] has been added to thisimplementation. 

4 France (French NA) — Uses the AnnexeNationale a la NF EN 1993-1-1:2005 versionof the code along with the French NationalAnnex.. 

5 Finland (Finnish NA) - Uses the SFS EN1993-1-1:2005 version of Eurocode 3 alongwith the Finnish National Annex.

6 Poland (Polish NA) - Uses the PN EN 1993-1-1:2005 version of Eurocode 3 along with thePolish National Annex.

Table 5B.5 - Table 5B1.2(B) - Numerical Code for EurocodeNational Annex

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3. CMM Parameter

The values of CMM for various loading and support conditions are as givenbelow:

CMMValue

Loading and Support Conditions

1

2

3

4

5

6

7

varying end moments and uniform loading

8

varying end moments and central point load

Table 5B.6 - Values for the CMM Parameter

4. Checking beam deflection

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With the TRACK parameter set to 4, the members included in a BEAM CHECKcommand will be checked for the local axis deflection rather than for thestress capacity using the current LOAD LIST.

If both stress capacity and deflection checks are required, then 2 parameterblocks with code checks are required, one with a TRACK 4 command and onewith a TRACK 0, 1 or 2, thus:

LOAD LIST 1 TO 10

PARAMETER 1

CODE EN 1993

TRACK 2 ALL

CODE CHECK MEMBER 1

***************************

LOAD LIST 100 TO 110

PARAMETER 2

TRACK 4 ALL

DFF 300 MEMB 1

DJ1 1 MEMB 1

DJ2 4 MEMB 1

CHECK CODEMEMB 1

Note: While both sets of code checks will be reported in the output file,only the last code check results are reported in the STAAD.Pro graphicalinterface.

5. CMT Parameter

The values of CMM for various loading and support conditions are as givenbelow:

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CMTValue

Description Diagram

1 (Default) : Concentrated Torqueat Ends. Ends Torsion fixed andWarping fixed

2 Concentrated Torque alonglength of member. Ends Torsionfixed and Warping free

3 Concentrated Torque alonglength of member. Ends Torsionfixed and Warping fixed

4 Uniform Torque in member.Ends Torsion fixed and Warpingfree

5 Uniform Torque in member.Ends Torsion fixed and Warpingfixed

6 Concentrated Torque in can-tilever. End Torsion fixed andWarping fixed

7 Uniform Torque in cantilever.End Torsion fixed and Warpingfixed

Table 5B.7 - Loading and Support Conditions represented byCMT Parameter Values

Note: For CMT = 2 and CMT = 3, you have the option of specifying thedistance at which the concentrated torque acts, measured from the startof the member. This can be done by using the ALH design parameter. TheALH parameter indicates the ratio of the distance of the point torque

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(from the start of the member) to the length of the member. Thisparameter will have a default value of 0.5 (i.e., the torque acts at thecenter of the span) and will accept values ranging from 0 to 1.

5B.7(B) Code Checking

The purpose of code checking is to ascertain whether the provided sectionproperties of the members are adequate. The adequacy is checked as per EN 1993-1-1:2005 and a corresponding National Annex (if specified). Code checking is doneusing the forces and moments at specific sections of the members.

When code checking is selected, the program calculates and prints whether themembers have passed or failed the checks; the critical condition; the value of theratio of the critical condition (overstressed for value more than 1.0 or any otherspecified RATIO value); the governing load case, and the location (distance fromthe start of the member of forces in the member where the critical conditionoccurs).

Code checking can be done with any type of steel section listed in Section 2B.4 orany of the user defined sections as described in Section 1.7.3 of the TechnicalReference Manual, with the exception of ISECTION. ISECTION has been currentlyexcluded since the option of Tapered section design is currently not supported inthe EC3 module. The EC3 (EN 1993) design module does not consider thesesections or PRISMATIC sections in its design process.

Note: Checks for slender sections to EN 1993-1-1 are limited to I-SECTIONS,TEE, SINGLE CHANNEL, SINGLE ANGLE and CIRCULAR & RECTANGULARHOLLOW SECTIONS.

Code checking for GENERAL sections can be also done using the EN1993 module.The program will design GENERAL sections as I sections by default. However, youare given the option to choose a ‘section type’ to be considered while designing themember. Refer to the description of the GST design parameter in Section 5B.6 (B)for details.

5B.8 (B) Member Selection

STAAD is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section,

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i.e., the lightest section, which fulfills the code requirements for the specifiedmember. The section selected will be of the same type section as originallydesignated for the member being designed. Member selection can also beconstrained by the parameters DMAX and DMIN, which limits the maximum andminimum depth of the members.

Member selection can be performed with all the types of steel sections with thesame limitations as defined in Section 5B.7(B) - Code Checking.

Selection of members, whose properties are originally input from a user createdtable, will be limited to sections in the user table.

Member selection cannot be performed on members whose section properties areinput as prismatic or as the limitations specified in Section 5.B.7(B)

5B.9 (B)  Tabulated Results of Steel Design 

For code checking or member selection, the program produces the results in atabulated fashion. The items in the output table are explained as follows:

a. MEMBER         refers to the member number for which the design isperformed.           

b. TABLE             refers to steel section name, which has been checked againstthe steel code or has been selected.           

c. RESULTS         prints whether the member has PASSED or FAILED. If the

RESULT is FAIL, there will be an asterisk (*) mark on front of the member.           d. CRITICAL COND     refers to the clause in EN 1993-1-1:2005 code which gov-

erns the design.

e. RATIO             prints the ratio of the actual stresses to allowable stresses forthe critical condition. Normally a value of 1.0 or less will mean the memberhas passed.           

f. LOADING        provides the load case number, which governed the design.          

g. FX, MY, and MZ        provide the axial force, moment in local Y-axis and themoment in local z-axis respectively. Although STAAD does consider all themember forces and moments (except torsion) to perform design, only FX,MY and MZ are printed since they are the ones which are of interest, in mostcases.

h. LOCATION      specifies the actual distance from the start of the member tothe section where design forces govern.          

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Note: For a TRACK 2 output, the module will also report all the relevant clausechecks that have been performed and will also indicate the critical ratio and theload case that caused the critical ratio as well as the corresponding forces thatwere used for the respective checks. A TRACK 2 output will also include thevarious design data used for the calculations such as the section modulii,section class, section capacity etc.

If an NA parameter (other than 0) has been specified and if the particular NationalAnnex requires additional checks outside those specified in EN 1993-1-1:2005(e.g., The Dutch National Annex), the respective NA clauses and any associatedcode clauses will be listed along with the critical ratios and the forces that wereused for these clause checks.

5B.(C) European Codes - National Annexesto Eurocode 3 [EN 1993-1-1:2005]A number of countries that have signed up to the replace their current steel designstandards with the Eurocode, EN 1993-1-1:2005, known commonly as Eurocode 3,have published their National Annex documents. These documents make smallchanges to the base document and STAAD.Pro has been updated to incorporatesome of these National Annex documents.

Description

The parameter NA sets the default material gamma factors and anyadditional changes outlined in the country specific National Annex such as specificequations or methods.

The output file printout has been updated to indicate which National Annex (if any)has been used in a code check / select process. (For all TRACK settings)

Note: This Eurocode 3 design code is secured using the 'Eurocode Design'code pack.

General Format

The format of the EN 1993-1-1:2005 National Annex is as follows:

CODE EN 1993

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NA f1

{Code parameters: See Eurocode 3 parameters} 

Where: f1 represents the number designation for a specific country's NationalAnnex:

NA Value Country

0 None. This value represents using the base codeonly, with no national annex changes or additions(default).

1 United Kingdom (British NA)

2 Netherlands (Dutch NA)

3 Norway (Norwegian NA)

4 France (French NA)

5 Finland (Finnish NA)

6 Poland (Polish NA)

Table 5B.8 - Numerical Code for Eurocode National Annex

Specifying the design engine to use a National Annex with EC 3

Use the following procedure to include additional check specified by a NationalAnnex:

1. In the Modeling mode, select theDesign | Steel tab.

The Steel Design - Whole Structure dialog box opens.

2. In the Current Code drop-down menu, select EN 1993-1-1:2005.

3. Click Define Parameters….

The Design Parameters dialog box opens.

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4. Select the NA parameter in the list box.

5. Select the option corresponding to the National Annex document you want touse .

6. Click Add.

This will insert the following commands into the STAAD input file:

CODE EN 1993-1-1:2005

NA 8

Refer to EC3 steel design for additional information on steel design per EC3.

A design performed to the new Eurocode 3 National Annex is displayed in theoutput file (*.ANL) with the following header, in addition to the base EC3 output.

5B.1(C) EC3 NA Dutch National Annex

Purpose

Adds values from the Dutch National Annex - titled NEN-EN 1993-1-1/NB - for usewith Eurocode 3, or EN 1993-1-1:2005. The NA document makes small changes tothe base document.

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Description

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) thatrequire additional clauses from the Dutch National Annex (hereafter referred to asD-NA) are:

l 6.1 General

l 6.2.8 Bending and shear

l 6.2.10 Bending shear and axial force

l 6.3 Buckling resistance of members

l 6.3.1.3 Slenderness for flexural buckling

l 6.3.1.4 Slenderness for torsional and torsional-flexural buckling

l 6.3.2.2 Lateral torsional buckling curves – General case

l 6.3.2.3 Lateral torsional buckling curves for rolled sections or equivalentwelded sections

l 6.3.2.4 Simplified assessment methods for beams

l 6.3.3 Members in bending and axial compression

Note: Refer to the basic code (EC3) for a description of these clauses. Thesections below refer to the corresponding clauses in the UK-NA.

Note: The local axis convention in the Dutch codes is: Y – major axis & Z –minor axis (as opposed to the convention followed in STAAD.Pro).

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Clause 6.1 – General

The partial safety factors will use the following values:

Resistance of cross-sections- ΓM0 = 1.0

Resistance of members to instability- ΓM1 = 1.0

Resistance of cross sections to tension- ΓM2 = 1.25

The design function in STAAD.Pro will set these values as the default values for theD-NA. The user is still however allowed to modify these factors using the Γparameters in the design input.

Clause 6.2.8 – Bending and shear

The D-NA requires the implementation of causes 11.3.1.1 and 11.3.1.3 of NEN6770.

Clause 11.3.1.1 (NEN 6770): Class 1 and Class 2 I-section profiles

Class 1 and class 2 I section profiles must satisfy the interaction formulae given intables 10 & 11 of NEN 6770.

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Table 10: Provides interaction checks for bending about the major axis (Allnecessary terms and formulae are described below):

l Check #1 – If Vz;s;d ≤ 0.5 Vz;pl;d and Ns;d ≤ 0.5 x a1 x Npl;d check equa-tion 11.3.1

l Check #2 – If Vz;s;d ≤ 0.5 Vz;pl;d and Ns;d > 0.5 x a1 x Npl;d check equa-tion 11.3.2

l Check #3 – If Vz;s;d > 0.5 Vz;pl;d and Ns;d ≤ 0.5 x a2 x Nv;u;d check equa-tion 11.3-3

l Check #4 – If Vz;s;d > 0.5 Vz;pl;d and Ns;d > 0.5 x a2 x Nv;u;d check equa-tion 11.3-4

Where:

Vz;s;d= Actual Shear force in the section along Z- axis

Vz;pl;d= Shear capacity of section  along Z - axis

= Aw x fy;d / √3 - See fig below for Aw ; fy;d = yield stress

Figure 5.5 - Definition of Aw

Aw = A - 2 (bf - tw - 2r) tf

Ns;d= Axial force in the section

Npl;d= Axial capacity of section = A x fy;d

My;s;d= Bending moment about major axis

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My;pl;d= Plastic moment capacity of section = fy;d x Wy;pl

Wy;pl =  Plastic section modulus

a1 = = min( A-2bfx tf)/A , 0.5)- used in tables 10 & 11

a2 = = see eqn 11.3-10- used in tables 10 & 11

Mv;y;ud= see eqn 11.3.12

N;v;u;d= see eqn 11.3-13

Table 11: Provides interaction formulae for bending about the minor axis

l Check #1 – If Vy;s;d ≤ 0.25 Vy;pl;d and Ns;d ≤ 1.0 x a1 x Npl;d check equa-tion 11.3-5

l Check #2 – If Vy;s;d ≤ 0.25 Vy;pl;d and Ns;d > 1.0 x a1 x Npl;d check equa-tion 11.3-6

l Check #3 – If Vy;s;d > 0.25 Vy;pl;d and Ns;d ≤ 1.0 x a1 x Nv;u;d checkequation 11.3-7

l Check #4 – If Vy;s;d > 0.25 Vz;pl;d and Ns;d > 1.0 x a1 x Nv;u;d checkequation 11.3-8

Where:

Vy;s;d= Actual Shear force in the section along Y- axis

Vy;pl;d= Shear capacity of section   along Y - axis

= Aw x fy;d / √3  - See fig below for Aw ; fy;d = yield stress

Mv;z;u;d = q x Mz;pld =  q x fy;d x Wpl;z;d (Wpl;z;d = plastic sectionmodulus about minor axis) & q as per eqn 11.3-14

Nv;u;d = N;pl;d – 2(1-q)bf x tf x fy;d

Clause 11.3.1.3 ( NEN 6770) : Class 1 and Class 2Square and rectangular hollow sections

This clause requires class 1 and class 2 square and rectangular tube profiles tosatisfy the interaction equations in Table 13.

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l Check #1 – If Vz;s;d ≤ 0.25 Vz;pl;d and Ns;d ≤ 0.5 x a3 x Npl;d check equa-tion 11.3.22

l Check #2 – If Vz;s;d ≤ 0.25 Vz;pl;d and Ns;d > 0.5 x a3 x Npl;d check equa-tion 11.3.23

l Check #3 – If Vz;s;d > 0.25 Vz;pl;d and Ns;d ≤ 0.5 x a4 x Nv;u;d checkequation 11.3-24

l Check #4 – If Vz;s;d > 0.25 Vz;pl;d and Ns;d > 0.5 x a4 x Nv;u;d checkequation 11.3-25

Where

Vz;s;d= Actual Shear force in the section along Z- axis

Vz;pl;d= Shear capacity of section   along Z – axis

[ b – breadth and h = height of section ; A= area of section]

a3 = min( (A-2xbxt)/A , 0.5)

a4 = from equation 11.3.27

Clause 6.2.10 – Bending shear and axial force

Requires the implementation of clauses 11.3.1.1 to 11.3.1.3 and 11.3.2.1 to11.3.2.3 of NEN 6770 and clause 11.3 of NEN 6771

Clause 11.3.1.1 (NEN 6770) and Clause 11.3.1.3 (NEN 6770)

See "5B.1(C) EC3 NA Dutch National Annex" on page 345 of this documentdescribed above.

Clause 11.3.1.2 (NEN 6770): Class 1 and class 2circular hollow (CHS) profiles

Class 1 and class 2 sections with circular hollow profiles should satisfy theinteraction equations given in table 12.

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l Check #1 – If Vz;s;d ≤ 0.25 Vz;pl;d check equation 11.3.17

l Check #2 – If Vz;s;d > 0.25 Vz;pl;d check equation 11.3.18.

See "5B.1(C) EC3 NA Dutch National Annex" on page 345 of this document forequations to derive Vz;s;d

Vz;pl;d = Shear capacity of CHS sections

See equations 11.3-19 and 11.3-20 to evaluate Mv;y;u;d and N;v;u;d.

To check for these conditions about the y axis, substitute the index ‘z’ in the aboveequations with ‘y’ (should be the same of CHS sections).

Clause 11.3.2 ( NEN 6770)

Section 11.3.2 in general deals with Biaxial bending with axial force and shear. Thegeneral condition to be satisfied in this case is given by equation 11.3-31 of NEN6770

Clause 11.3.2.1 : Class 1 and class2 I-sections withbiaxial bending + shear + axial force

The formula to evaluate M;N;v;y;u;d and M;N;v;z;u;d are to be taken from tables14 and 15 of NEN 6770 respectively.

Checks for table 14:

l Check #1 – If Vz;s;d ≤ 0.5 Vz;pl;d and Ns;d ≤ 0.5 x a1 x Npl;d use equation11.3.32

l Check #2 – If Vz;s;d ≤ 0.5 Vz;pl;d and Ns;d > 0.5 x a1 x Npl;d use equation11.3.33

l Check #3 – If Vz;s;d > 0.5 Vz;pl;d and Ns;d ≤ 0.5 x a2 x Nv;u;d use equa-tion 11.3-34

l Check #4 – If Vz;s;d > 0.5 Vz;pl;d and Ns;d > 0.5 x a2 x Nv;u;d use equa-tion 11.3-35

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See "5B.1(C) EC3 NA Dutch National Annex" on page 345 of this document forequations to evaluate Vz;s;d, My;pl;d, Npl;d, Mv;y;ud, N;v;u;d, a1 ,a2 and Vz;pl;d.

Checks for table 15:

l Check #1 – If Vy;s;d ≤ 0.25 Vy;pl;d and Ns;d ≤ 1.0 x a1 x Npl;d use equa-tion 11.3.36

l Check #2 – If Vy;s;d ≤ 0.25 Vy;pl;d and Ns;d > 1.0 x a1 x Npl;d use equa-tion 11.3.37

l Check #3 – If Vy;s;d > 0.25 Vy;pl;d and Ns;d ≤ 1.0 x a1 x Nv;u;d checkequation 11.3-38

l Check #4 – If Vy;s;d > 0.25 Vy;pl;d and Ns;d > 1.0 x a1 x Nv;u;d checkequation 11.3-39

See "5B.1(C) EC3 NA Dutch National Annex" on page 345 of this document forequations to evaluate Vy;s;d, Mz;pl;d, Npl;d, Mv;z;ud, N;v;u;d, a1 ,a2 and Vy;pl;d.

See table 16 for α1, α1, β0 and β1 use in tables 14 and 15.

Clause 11.3.2.2 : Class 1 and Class 2 Circular hol-low tubes

The formula to evaluate M;N;v;y;u;d and M;N;v;z;u;d (to be used in equation 11-3-31, see description of  clause 11.3.2 above) are to be taken from table 17 ofNEN 6770.

l Check #1 – If Vz;s;d ≤ 0.25 Vz;pl;d use equation 11.3.44

l Check #2 – If Vz;s;d > 0.25 Vz;pl;d use equation 11.3.45.

See "5B.1(C) EC3 NA Dutch National Annex" on page 345 of this document forequations to evaluate Vz;pl;d, My;pl;d, and Npl;d use in equations 11.3.44 &11.3.45.

For values to be used for α1, α2,  β1 and  β2 in this case refer to table 18 of NEN6770.

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Clause 11.3.2.3 : Class 1 and class2 Rectangularand square hollow tubes

The formula to evaluate M;N;v;y;u;d and M;N;v;z;u;d (to be used in equation 11-3-31, see description of  clause 11.3.2 above) are to be taken from table 19 of NEN6770.

l Check #1 – If Vz;s;d ≤ 0.25 Vz;pl;d and Ns;d ≤ 0.5 x a3 x Npl;d use equa-tion 11.3-48

l Check #2 – If Vz;s;d ≤ 0.25 Vz;pl;d and Ns;d > 0.5 x a3 x Npl;d use equa-tion 11.3.49

l Check #3 – If Vz;s;d > 0.25 Vz;pl;d and Ns;d ≤ 0.5 x a4 x Nv;u;d use equa-tion 11.3-50

l Check #4 – If Vz;s;d > 0.25 Vz;pl;d and Ns;d > 0.5 x a4 x Nv;u;d checkequation 11.3-51

See "5B.1(C) EC3 NA Dutch National Annex" on page 345 of this document forequations to evaluate Vz;pl;d, My;pl;d, Npl;d, Mv;y;ud, N;v;u;d, a3, a4 and Vz;pl;d to be used in the above equations. For values to be used for α1, α2, β1 andβ2 in this case refer to table 20 of NEN 6770.

To check for these conditions about the y axis, substitute the index ‘z’ in the aboveequations with ‘y’.

Clause 11.3 ( NEN 6771)

In general, this section deals with Biaxial bending with axial force and shear forclass 3 and class 4 sections.

Check for class 3 sections: For class 3 sections use the method in section 11.3 NEN6770. For class 3 sections the methods and equations discussed above can be usedwith the ‘plastic section modulus’ being substituted with the ‘elastic modulus’.

Check for class 4 sections: Class 4 sections can be treated as class 3 sections if theeffective section properties are used as given in clause 10.2.4.2.3 of NEN 6771.Working out the effective section properties for slender sections has already beendone in STAAD.Pro.

For I- section profiles and tubular sections the following procedure should beadopted:

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1. Case 1: -If M;y;s;d / MN;y;f;u;d ≤ 1 check equation 11.2-7 ( given below)

Vz;s;d

/Vz;u;d

≤ 1

Where

Vz;s;d

is the shear for in the Z direction

Vz;u;d

is the shear capacity in the Z direction for ultimate limitstate.

For an I section,

Where

Aw,ef = effective web area as given in section 10.2.4.2.3 .

MN;y;f;u;d is the moment capacity about the Y axis for theeffective section. = ( fy·W,eff)

2. Case 2: If M;y;s;d / MN;y;f;u;d > 1 and M;y;s;d / M;y;f;u;d ≤1  checkequation 11.2-13 (given below):

Clause 6.3 – Buckling resistance of members

The D-NA introduces a new clause 6.3.0, which in turns requires the checks as perclauses 12.1.2.2, 12.13.2 and 12.1.4.2 of NEN 6771 to be applied.

Clause 12.1.2.2 (NEN 6771)

This clause in NEN 6771 determines the relative torsional slenderness and is givenas:

Where:

Nc;u;d

= A·fy;d

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A = area of section

fy;d= the yield stress

FE;θis the Euler-torsion formula

This value of slenderness is to be used to calculate the modification factors used insection 6.3 of EC-3.

Clause 12.1.3.2 (NEN 6771)

This clause works out the relative torsional-flexural buckling slenderness forcompression members. The relative torsional-flexural buckling slenderness is givenas:

Where

Nc;u;d

= A·fy;d

A = area of section

fy;d= yield stress

FE;tk

is the Euler torsional buckling strength

Clause 12.1.4.2 (NEN 6771)

Buckling lengths of rotationally restrained bars with intermediate spring supports.

Note: STAAD.Pro does not allow for these end conditions, specifically. Theeffective length factors may be used to accommodate this requirement.

Clause 6.3.1.3 – Slenderness for flexural buckling

The Dutch NA requires the implementation of clause 12.1.1.3 and 12.1.5.3.2 ofNEN 6770 and clause 12.1.1.3 of NEN 6771.

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Clause 12.1.1.3 (NEN 6770)

This clause gives the equations to evaluate the effective lengths for varioussupport conditions. STAAD.Pro uses the effective length factor ‘K’ which allows theuser to set/modify the effective lengths for a member.

Clause 12.1.5.3.2 (NEN 6770)

This clause gives methods to evaluate the buckling length of lattice sections. Wedo not deal with latticed section in the current version of STAAD.Pro. In any casethe buckling length can be adjusted using the ‘K’ factor.

Clause 12.1.1.3 (NEN 6771)

This clause again deals with working out the effective lengths of prismatic andnon-prismatic rods. Again, the ‘K’ factor in the current implementation ofSTAAD.Pro is adequate to cater for adjusting the effective lengths as necessary.

Clause 6.3.1.4 – Slenderness for torsional and torsional-flexuralbuckling

The D-NA requires the implementation of clauses 12.1.2 and 12.1.3 of NEN 6770

Clause 12.1.2 (NEN 6770): Torsional stability

IPE, HEA, HEB & HEM sections and pipe sections do not need to be checked fortorsional instability.

If torsional checks need to be performed they should be done according to 12.1.2of NEN 6771.

Clause 12.1.2 (NEN 6771)

This clause gives the condition to check for torsion instability. The conditionbeing:

Where:

Nc;s;d

= the applied axial load

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NC;u;d

= the axial capacity = A x fy.

Clause 12.1.3 (NEN 6770): Torsional flexural sta-bility

Doubly symmetric sections need not be checked for torsional flexural instability.However for I sections that have rigid supports that is not along the axis of thesection and any other sections will need to be checked as per clause 12.1.3 of NEN6771.

Clause 12.1.3 (NEN 6771)

This clause gives the condition to check for torsional flexural instability. Thecondition being:

Where

N;c;s;d and N;c;u;d as in clause 12.1.2 above.

Clause 6.3.2.2 – Lateral torsional buckling curves - general

The D-NA states that the values for the imperfection factor αLT to be used inequation 6.56 of EC-3 are to be obtained from table 6.3 of EC-3. This is whatSTAAD.Pro currently implements.

Clause 6.3.2.3 – Lateral torsional buckling curves for rolled sectionsor equivalent welded sections

The D-NA states that:

1. The values for the

#. Imperfection factor αLT0 = 0.4 (to be used in equation 6.57 of EC-3)

#. Β = 0.75(to be used in equation 6.57 of EC-3)

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These are the default values used in the current implementation inSTAAD.Pro.

2. The buckling curves shall be selected as per table 6.5.

Again this is what is being used in the current implementation of EC3 (BS) inSTAAD.Pro.

3. The reduction factor, f, is given by

F = 1 – 0.5(1-kc)[1-2x (λLT -0.8)^2]. And Kc to be determined from table 6.6.

The current implementation of STAAD.Pro conservatively uses a value of f =1.0. This implementation use a new parameter KC to identify the momentdistribution as given in table 6.6, thus determining the value of thecorrection factor ‘kc’.

Clause 6.3.2.4 – Simplified assessment method for restrained beamsin buildings

The current implementation only uses the more accurate method (6.3.2.2 and6.3.2.3 in EC-3). Hence STAAD will ignore this clause for this implementation.

Clause 6.33 – Uniform members in bending and axial compression

The D-NA recommends the use of the method in Annex B of EC-3 to determine thevalues of kyy, kyz, kzy and kzz to be used  in 6.3.3 ( EC-3) checks.

The current implementation in STAAD.Pro uses the method in Annex B.

The Dutch NA also requires additional checks as per clause 12.3.1.2.3 of NEN6770

Clause 12.3.1.2.3 (NEN 6770): Rotation/bendingcapacity

The checks given in this clause deals with additional checks for columns that formpart of a buttressed or non-butressed framework.  The program uses the ESTIFFparameter with two different values to identify the framework type:

l ESTIFF = 0 (default) – Column part of a buttressed framework – Selectingthis value will internally perform the checks as per section 1 of clause

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12.3.1.2.3

l ESTIFF = 1 (default) – Column is not part of a buttressed framework – Select-ing this value will internally perform the checks as per section 2 of clause12.3.1.2.3

These checks are described below:

1. For columns in buttressed frameworks the buckling length is to be takenbased on either

l the system length or

l the distance between adjacent lateral supports

The following conditions should also be satisfied:

If Nc;s;d/ Npl;d < 0.15, no additional checks are required

If Nc;s;d/ Npl;d ≥ 0.15 and the steel grade is S235 or S 275 then

Where

Nc;s;d

is the axial load in the section

Npl;d

= Axial capacity of section = A·fy;d

λy= Slenderness of the section about the major axis ( Y-axis)

If Nc;s;d/ Npl;d ≥ 0.15 and the steel grade is S355 then

Where

Nc;s;d

= the axial load in the section

Npl;d

= Axial capacity of section = A·fy;d

λy= Slenderness of the section about the major axis ( Y-axis)

2. For columns that are not part of buttressed frameworks the followingadditional checks need to be done:

If Nc;s;d/ Npl;d < 0.15, no additional checks are required

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If Nc;s;d/ Npl;d ≥ 0.15 and the steel grade is S235 or S 275 then

Where

Nc;s;d

= the axial load in the section and

Npl;d

= Axial capacity of section = A·fy;d

λy= Slenderness of the section about the major axis ( Y-axis)

If Nc;s;d/ Npl;d ≥ 0.15 and the steel grade is S355 then

5B.2 (C) EC3 NA Norwegian National Annex

Purpose

Adds values from the Norwegian National Annex - titled NA to BS EN 1993-1-1:2005 - for use with Eurocode 3, or EN 1993-1-1:2005. The NA document makessmall changes to the base document.

Description

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) thatrequire additional clauses from the Norwegian National Annex are:

Section 6.1(1)

The partial safety factors will use the following values:

Resistance of cross-sections - ΓM0 = 1.05

Resistance of members to instability - ΓM1 = 1.05

Resistance of cross sections to tension - ΓM2 = 1.25

This implementation will set the default values of the GM0, GM1 and GM2parameters in the design module to the values as:

GM0 = 1.05, GM1 = 1.05 and GM2 = 1.25. (Note: When NA 3 has been specified)

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The user will be allowed to override these default values and set custom values tothese parameters. If any of these parameters have been specified by the user as ‘0’,this implementation will ignore the user specified value (i.e., 0) and use the defaultvalues as given above.

The design functions in STAAD.Pro will set these values as the default values forthe French-NA. The user is still however allowed to modify these factors using the Γparameters in the design input. These values will also need to be reported in thedesign output.

Note: The ‘GB1’ parameter that is being used for compression checks in buildspreceding this release (STAAD.Pro 2007 build 06) has been removed as thisparameter is no longer required in EN 1993-1-1:2005. Hence any legacy filesthat use GB1 parameter will indicate an error message and the user will need tosubstitute GB1 with GM1 in line with EN 1993-1-1:2005.

Note: Refer to the basic code (EC3) for a description of these clauses. Thesections below refer to the corresponding clauses in the Norwegian -NA.

5B.3 (C) EC3 NA UK National Annex

Purpose

Adds values from the UK National Annex - titled NA to BS EN 1993-1-1:2005 - foruse with Eurocode 3, or EN 1993-1-1:2005. The NA document makes smallchanges to the base document.

Description

The clauses/sections in EN 1993-1-1:2005 that have been dealt with in the UKNational Annex (hereafter referred to as the UK-NA) are:

l 6.1(1) General

l 6.3.2.2 Lateral Torsional Buckling curves – General case

l 6.3.2.3(1) Lateral Torsional buckling curves for rolled or equivalent weldedsections

l 6.3.2.3(2) Modification factor calculations

l 6.3.2.4(1)B Slenderness limit λc0

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l 6.3.2.4(2)B Modification factor ‘kfl’

l 6.3.3 Method for calculation interaction factors for members in combinedbending and compression

l Annex B Members in bending and axial compression

l 6.3.1.4 Slenderness for torsional and torsional- flexural buckling

Note: Refer to the basic code (EC3) for a description of these clauses. Thesections below refer to the corresponding clauses in the UK-NA.

Clause 6.1(1) – General: Partial Safety Factors for buildings

EN 1993-1-1:2005 specifies the use of the partial safety factors to be used in fordesign as given in Cl. 6.1 of the code. These factors are ΓM0, ΓM1 & ΓM2. EN 1993provides default values for these factors. However any National Annex is allowedto override these default values.

The partial safety factors will use the following values for the UK National Annex:

Resistance of cross-sections- ΓM0 = 1.0

Resistance of members to instability- ΓM1 = 1.0

Resistance of cross sections to tension- ΓM2 = 1.1

This implementation will hence set the default values of the design parametersGM0, GM1 and GM2 in the design module to the values as:

GM0 = 1.0, GM1 = 1.0 and GM2 = 1.10. (Note: When NA 1 has been specified)

The design function in STAAD.Pro will set these values as the default values for theUK-NA. You may override these default values and set custom values to theseparameters. These values will also be reported in the design output.

Note: If any of these parameters have been specified by the user as ‘0’,STAAD.Pro will ignore the user specified value (i.e., 0) and use the defaultvalues as given above.

Warning: The ‘GB1’ parameter that is being used for compression checks inbuilds preceding this release (STAAD.Pro 2007 build 06) has been removed as

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this parameter is no longer required in EN 1993-1-1:2005. Hence any legacyfiles that use GB1 parameter will indicate an error message and the user willneed to substitute GB1 with GM1 in line with EN 1993-1-1:2005.

Clause 6.3.2.2 –Elastic critical moment and imperfection factors forLTB checks

The UK-NA recommends the use of Table 6.3 and 6.4 of BS EN 1993-1-1:2005 tocalculate the imperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor XLT, requires the calculation of the

‘Elastic Critical Buckling Moment’, Mcr. The UK National Annex does not specify aparticular method to calculate Mcr. Hence the calculation of Mcr has been based onthe following NCCI documents:

1. SN003a-EN-EU – Elastic critical moment for Lateral torsional Buckling:

This document provides a method to calculate ‘Mcr’ specifically for doublysymmetric sections only. Hence only doubly symmetric sections will beconsidered for this method in the proposed implementation.

The equation to evaluate Mcr is given in the NCCI as

C1 and C2 are factors that depend on the end conditions and the loadingconditions of the member. The NCCI provides values for C1 and C2 for thedifferent cases as given in the tables below:

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This NCCI considers three separate loading conditions:

l Members with end moments

l Members with transverse loading

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l Members with end moments and transverse loading.

The implementation of EC3 in STAAD.Pro accounts for the loading conditionand the bending moment diagram through the CMM parameter. The first twoloading conditions mentioned above and its variants can be dealt with byusing the existing values of the CMM parameter (i.e., 1 to 6). Hence theappropriate values from this NCCI will be used for ‘C1’ and ‘C2’ coefficientsdepending on the value of CMM specified.  The default value of CMM is 1,which considers the member as a pin ended member with UDL along its span.The user will also have the option to specify specific values for C1 & C2 usingthe new ‘C1’ and ‘C2’ parameters in the design input mode.

However for cases with end moments and transverse loading, the NCCIprovides graphs to evaluate the C1 and C2 coefficients. It does not however,provide a set of equations for these graphs. However the “end moments andtransverse loading” condition cannot be currently specified in the designinput. Hence this implementation will introduce two new values for the CMMparameter viz.

CMM 7:Member with varying end moments and uniform loading.

CMM 8: Member with varying end moments and central point load.

For these two conditions, the UK National Annex (nor the NCCI) does notprovide equations to evaluate C1 and C2. Hence in STAAD.Pro the user willhave to use the new ‘C1’ & ‘C2’ parameters to input the required values for C1& C2 to be used in calculating Mcr. For values of 7 or 8 for the CMMparameter, the program will issue a warning if C1 and C2 have not beenspecified.

Note: If the NA parameter has not been specified, the program obtainsthe values of C1 and C2 from Annex F of DD ENV version of 1993-1-1:1992.

2. SN030a-EN-EU – Mono-symmetrical uniform members under bending andaxial compression:

This document provides a method to evaluate the elastic critical moment(Mcr) for uniform mono symmetric sections that are symmetric about theweak axis. Hence for this implementation the elastic critical moment for ‘Tee-Sections’ will be worked out using the method in this NCCI.

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Note: Though this method could also be applicable to mono-symmetric built-up sections, STAAD.Pro currently does not have a means to specify/identifya mono-symmetric built-up section. Hence this implementation will use thismethod only for Tee-Sections. In any case, the actual LTB capacity will stillbe worked out as per BS 5950-1 as in the current EC3 implementation.

The equation to evaluate Mcr for mono symmetric sections is given as :

The factors C1, C2 and C3 are dependent on the end conditions and loadingcriteria. This implementation will consider C1, C2 and C3 as given in thetables below:

The CMM parameter (see section (i) above) specified during design input willdetermine the values of C1, C2 and C3. The default value of CMM is 1, which

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considers the member as a pin ended member with UDL along its span. ThisNCCI does not however consider the “end moments and transverse loading”condition. The user however can use the new C1, C2 and C3 parameters toinput the required values for C1, C2 and C3 to be used in calculating Mcr. Asdescribed in section (i) above, the user must use C1, C2 and C3 parametersalong with CMM values of 7 and 8.

Both the NCCI documents mentioned above assume that the member underconsideration is free to rotate on plan and that there are no warping restraintsfor the member ( k = kw = 1.0). The current implementation of EC3 inSTAAD takes into account of the end conditions using the CMN parameter. Avalue of K = kw =1 is indicated by a value of CMN = 1.0 in the design input. Hence the above methods will be used only for members which are free torotate on plan and which have no warping restraints, i.e., CMN = 1.0. Formembers with partial or end fixities (ie, CMN = 0.5 or CMN = 0.7), theproposed implementation will fall back on to the method and coefficients inDD ENV 1993-1-1:1992 – Annex F.

For all cases that are not dealt with by the National Annex (or the NCCIdocuments) the proposed implementation will use the method as per the DDENV 1993-1-1:1992 code.

The term ‘zg’ in the equation to calculate Mcr refers to the distance betweenthe point of application of load on the cross section in relation to the shearcenter of the cross section. The value of ‘zg’ is considered positive if the loadacts towards the shear center and is negative if it acts away from the shearcenter. By default, the program will assume that the load acts towards theshear center at a distance equal to (Depth of section/2) from the shear center.The user will be allowed to modify this value by using the new ‘ZG’parameter. Specifying a value of ZG = 0 in the design input would indicatethat the load acts exactly at the shear center of the section so that the term ‘zg’in the equation will have a value of zero.

Clause 6.3.2.3(1) – LTB for rolled sections or equivalent welded sec-tion

The UK-NA specifies different values for the λLT,0 and β factors to be used inequation 6.57 of BS EN 1993-1-1 for rolled and equivalent welded sections. Thecurrent implementation in STAAD.pro does not differentiate between rolled andwelded sections and uses the default values in BS EN 1993-1-1 for λLT,0 and β.

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The values specified in the UK-NA are:

For rolled sections and hot-rolled & cold formed hollow sections:

λLT,0 = 0.4

β = 0.75

For welded sections:

λLT,0 = 0.2

β = 1.00

The current implementation of STAAD.Pro uses the buckling curves based onTable 6.5 of BS EN 1993-1-1:2005. The UK-NA specifies different limits andbuckling curves to be used in this clause as given below:

This table again does not specify which buckling curve is to be used in case ofwelded doubly symmetric sections with h/b ≥ 3.1 and welded non-doublysymmetric sections. Hence for these cases the new implementation will still use themethod specified in the base code as per clause 6.3.2.2(2).

Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTB Reduction factor,χLTas per UK NA

Clauses 6.3.2.2 and 6.3.2.3 (EN 1993-1-1:2005), both give equations to evaluatethe LTB reduction factor χ

LTto be used in eqn. 6.55 of BS EN 1993-1-1:2005.

Cl. 6.3.2.2 uses tables 6.3 and 6.4 to choose the buckling curve and theimperfection factors to be used for calculating χ

LT. Table 6.4 specifies the choice of

buckling curves for “Rolled I Sections”, “Welded I Sections” and “Any other

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sections”. Cl 6.3.2.3 on the other hand uses tables 6.5 and 6.3 to choose thebuckling curves and imperfection factors. Table 6.5 however only deals with“Rolled I Sections” and “Welded I Sections”.

Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending members ofconstant cross section the value of χ

LTshould be determined from...”. Hence in the

implementation of EC3 (and the UK Annex) in STAAD.Pro, by default the programwill consider clause Cl. 6.3.2.3 to evaluate χ

LT. For any case that is not dealt with

by Cl. 6.3.2.3, the program will consider Cl. 6.3.2.2 to evaluate χLT.

Cl. 6.3.2.3 in the UK National Annex states that Table 6.5 in BS EN 1993-1-1:2005should be replaced with the table given in the NA (See section 4.3 of thisdocument). Hence for all cases dealt with by the table in the UK NA, thisimplementation will choose the buckling curves from the UK National Annex. Forany case that is not dealt with by the table in the UK NA, the program will use themethod given in Cl. 6.3.2.2 of BS EN 1993-1-1:2005.

Hence for the following cross sections the program will use the Table in the UK NAfor choosing a buckling curve for LTB checks (when the UK NA has been specified):

l Rolled doubly symmetric I & H Sections

l Rolled doubly symmetric hollow sections (SHS, RHS, CHS)

l Angle Sections

l Any other rolled section

l Welded doubly symmetric sections with h/b < 3.1

For the following cross sections, the program will use Cl. 6.3.2.3 of BS EN 1993-1-1:2005 to evaluate χLT

l Welded I & H Sections with h/b ≥ 3.1.

For any other type of cross section that is not dealt with by the National Annex orCl.6.3.2.3, the program will use Cl. 6.3.2.2 to evaluate χLT .

In any case the Elastic critical moment “Mcr” (used to evaluate the non dimensionalslenderness) will be worked out as given in section 4.2 of this document. Since theUK National Annex uses the NCCIs mentioned in the sections above, thisimplementation will only consider end restraint conditions corresponding to theCMN parameter=1.0 (See section 4.2 above). For all other cases of the CMNparameter values, this implementation will use the method specified in Annex F ofDD ENV 1993-1-1:1992.

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Note: If a National Annex has not been specified (i.e., NA parameter in thedesign input = 0), the program will use Cl. 6.3.2.3 only in the case of Rolled orwelded I & H Sections. For all other cases, the program will use Cl. 6.3.2.2 ofBS EN 1993-1-1:2005. Also, I sections with plates will be treated as built-upsections only if the section has been explicitly specified as a built-up section(i.e., SBLT parameter = 1.0 in design input).

Clause 6.3.2.3(2) – Modification factor, ‘f’ for LTB checks

The UK NA specifies the use of eqn. 6.58 of BS EN 1993-1-1:2005 to evaluate themodification factor ‘f’ for the LTB reduction factor χLT. To evaluate themodification factor BS EN 1993-1-1:2005 uses a correction factor ‘kc’ given byTable 6.6 in the code.

The UK-NA however, specifies that the correction factor ‘kc’ is to be obtained asbelow:

Kc = 1 / √C1, where C1 is to be obtained from the NCCI documents given insection 4.2 of this document. The NCCI document SN003a-EN-EU specifies thevalues of C1 to be used in table 3.1 as shown below.  This proposedimplementation will allow for the reduction factor based on the UK-NA.

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These values are for an end restraint factor of k=1 (ie CMN=1.0). Hence for allother values of CMN (ie 0.7 or 0.5) this implementation will use the values of C1from DD ENV 1993-1-1:1992 Annex F.

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The program will use a default value of 1.0 for ‘kc’. However the user can alsoinput a custom value of ‘kc’ by setting the design parameter ‘KC’ to the desiredvalue. The user can also get the program to calculate the value of ‘kc’ automaticallyby setting the value of the ‘KC’ parameter in the design input to 0. This will causethe program to evaluate a value of C1 corresponding to the end conditions and theBending moment of the member and in turn calculate ‘kc’ as given in the NA. Toevaluate C1, the program will use the NCCI documents mentioned in section 4.2 ofthis document.

Clause 6.3.2.4(1) B – Slenderness for flexural buckling

The UK NA specifies the value of λc0 for I, H channel or box section to be used inequation 6.59 of BS EN 1993-1-1:2005 as 0.4.

Note: STAAD.Pro does not use this clause in the current implementation ofEC-3. Hence this clause will be ignored for the UK National Annex.

Clause 6.3.2.4(2)BModification factor ‘kfl’

The value of the modification factor kfl to be used in equation 6.60 of BS EN 1993-1-1 to be as follows:

= 1.0 for hot rolled I sections

= 1.0 for welded I section with h/b ≤ 2

= 0.9 for other sections

Note: STAAD.Pro does not use this clause in the current implementation ofEC-3. Hence this clause will be ignored for the UK National Annex.

Clause 6.3.3(5) – Interaction factors kyy, kyz, kzy and kzz

The UK-NA recommends that the method in Annex A or Annex B of BS EN 1993-1-1:2005 can be used to calculate the interaction factors for Cl. 6.3.3 checks in thecase of doubly symmetric sections. The proposed implementation will hence useequations in Annex B of BS EN 1993-1-1:2005 to calculate these interactionfactors for doubly symmetric sections. The current implementation of EC3 BS in

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STAAD.pro uses the method in Annex B.

However for non-doubly symmetric sections, the UK NA gives the option of usingAnnex B with some modifications as given in the NA. (Cl. NA-3.2 of the UK NA).The UK NA requires additional checks to be done to check for the maximumallowable values of λ and X to be used in equations 6.61 and 6.62 of BS EN 1993-1-1:2005.

As per the UK NA, for non-doubly symmetric sections, the slenderness about theweak axis (λy in STAAD) and the corresponding reduction factor χy should be takenas the values from the highest values of slenderness (λ) among the flexuralbuckling slenderness (λy), torsional slenderness (λ

T) and torsional-flexural

slenderness (λTF) as given in Clauses 6.3.1.3 and 6.3.1.4 of BS EN 1993-1-1:2005.

Hence for non-doubly symmetric sections  the program will calculate the criticalnon-dimensional slenderness as:

λy = max

λTis calculated as λ

T= Ncr = min (N

CrT, N

crTF).

The UK NA or EC3 does not however specify a method to evaluate NCrT or NcrTF.Hence this implementation will use the method specified in the NCCI document“SN001a-EN-EU: Critical axial load for torsional and flexural torsional bucklingmodes” to calculate these. See section 4.9 below for details.

Note: The UK National Annex or EC3 does not deal with angle sections in specificand hence this implementation will use the method used in the current EC3implementation to deal with slenderness of angle sections. In the currentimplementation this is done as per cl 4.7.10 of BS 5950. This proposedimplementation will still use the same method for single and double angle sectionsto evaluate the slenderness.

Clause NA 3.2 of the UK NA also requires that “Where the section is not an I Sectionor a hollow section and is a class1 or class 2 section, it will be treated as a class 3section for the purposes of this clause”. Hence for all Class 1 or Class 2 crosssections that are NOT I, H, SHS, RHS or CHS sections, the elastic properties will beused for the purposes of 6.3.3 checks.

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Clause 6.3.1.4 - Slenderness for torsional and torsional- flexuralbuckling

Equations 6.52 and 6.53 of BS EN 1993-1-1:2005 are to be used to calculate thenon-dimensional slenderness λ

T,  to be used for torsional and torsional-flexural

buckling checks. The current implementation of EC3 in STAAD.pro does not allowfor this clause as BS EN 1993-1-1:2005 does not provide equations to calculatethe elastic critical loads Ncr,T,F and Ncr,T (refer 6.3.14 of BS EN 1993-1-1:2005).

The NCCI document “SN001a-EN-EU: Critical axial load for torsional and flexuraltorsional buckling modes” provides methods to calculate the Ncr,TF and NcrTfactors and hence will to be included in the proposed implementation of the UKNA.

The critical axial load for Torsional buckling is worked out as:

where, iy and iz are the radius of gyration about the Y-Y (weak axis) and Z-Z(strong axis) respectively.

The critical axial load for Torsional-Flexural buckling is worked out as:

For details on these equations refer to the NCCI document SN001a-EN-EU.

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5B.4 (C) EC3 NA French National Annex

Purpose

Adds values from the French National Annex - titled Annexe Nationale a la NF EN1993-1-1:2005 - for use with Eurocode 3, or EN 1993-1-1:2005. The NAdocument makes small changes to the base document.

Description

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that havebeen dealt with in the French National Annex (hereafter referred to as FR-NA) andthat are relevant to the proposed implementation are:

l 3.2.1(1) Material properties

l 6.1(1) General

l 6.3.2.2 Lateral Torsional Buckling curves – General case

l 6.3.2.3(1) Lateral Torsional buckling curves for rolled or equivalent weldedsections

l 6.3.2.3(2) Modification factor calculations

l 6.3.2.4(1)B Slenderness limit λc0

l 6.3.2.4(2)B Modification factor ‘kfl’

l 6.3.3 Method for calculation interaction factors for members in combinedbending and compression

l Annex A Members in bending and axial compression

l 6.3.1.4 Slenderness for torsional and torsional- flexural buckling

Note: Refer to the basic code (EC3) for a description of these clauses. Thesections below refer to the corresponding clauses in the French-NA.

Clause 3.2.1(1) - Material Properties

The material strengths (i.e., - steel grade strengths) to be used with NF EN 1993-1-1 is given in Table 3.1 of the code. The French National Annex however, specifies aseparate table (Table 3.1 NF) for the yield and tensile strengths of steel grades.

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This new table replaces Table 3.1 in NF EN 1993-1-1:2005. Table 3.1 NF excludessteel grades from standards EN 10210-1 and EN 10219-1 that are given in EC-3.

STAAD.Pro uses the steel grades and values from the table given in the NationalAnnex (i.e., - Table 3.1 NF). Table 3.1 NF is similar to table 3.1 in EC3, apart fromthe ‘fu’ values for S 355 and S355 W grade steel.

If you specify a steel grade that is not given in the Annex Table 3.1 (NF) but ispresent in Table 3.1 of EN 1993-1-1:2005, this implementation will use the valuesfrom Table 3.1 of EN 1993-1-1:2005. The appropriate yield strength used (fy) willbe shown in the design output file.

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Clause 6.1(1) – General

The partial safety factors will use the following values:

l Resistance of cross-sections - ΓM0 = 1.0

l Resistance of members to instability - ΓM1 = 1.0

l Resistance of cross sections to tension - ΓM2 = 1.25

STAAD.Pro sets the default values of the GM0, GM1 and GM2 parameters in thedesign module to the values as:

GM0 = 1.0

GM1 = 1.0

GM2 = 1.25

Note: When NA 4 has been specified.

You may override these default values and set custom values to these parameters.

Note: If any of these parameters have been specified by the user as ‘0’,STAAD.Pro will ignore the specified value and use the default values as givenabove.

Warning: The GB1 parameter (which, in fact was common to the base EC-3and was a reminiscent of the previous DD ENV implementation of EC-3) hasbeen removed. Hence any legacy STAAD files that have the GB1 Parameterdefined will need to be revised to take out this parameter as it is no longer validas per the latest EN1993.

Clause 6.3.2.2 –Elastic critical moment and imperfection factors forLTB checks

The French NA recommends the use of Table 6.3 and 6.4 of NF EN 1993-1-1:2005to calculate the imperfection factors for Lateral Torsional Buckling (LTB) checks.

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The calculation of the LTB reduction factor χLT, requires the calculation of the“Elastic Critical Buckling Moment”, Mcr. The French NA gives a method to evaluateMcr in its “Annex MCR”. This implementation will make use of this method toevaluate Mcr. Annex MCR however deals with the calculation of Mcr for doublysymmetric sections. Hence this implementation will use this method only fordoubly symmetric sections. For mono symmetric sections that are symmetric aboutthe minor axis (i.e Tee sections) this implementation will use the method from theNCCI document SN030a-EN-EU as given in the section below. For any other typeof section that is not dealt with by the Annex, this implementation will use themethod and tables given in Annex F of DD ENV 1993-1-1:1992.

1. Annex MCR

This document provides a method to calculate ‘Mcr’ specifically for doublysymmetric sections only. Hence only doubly symmetric sections will beconsidered for this method in this implementation.

The equation to evaluate Mcr is given as :

C1 and C2 are factors that depend on the end conditions and the loadingconditions. The NCCI provides values for C1 and C2 for the different casesas given in Table1 and Table 2 of the Annex. Table 1 deals with the conditionof a simply supported member with end moments and the value of C1 isdetermined by the end moment ratio (Refer to the NA for details). Clause 3.2of the National Annex however gives a formula to evaluate C1 as :

This formula however does not match the values given in Table 1 of the NA.Hence this implementation will use the values of C1 from Table 1 if the endmoment ration (ψ) is exactly equal to the values of ψ in the table. For allother cases this implementation will calculate the value of C1 from equation(6) in the Annex.

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The value of C2 will be determined from Table 2 of the Annex based on theloading and end conditions (i.e the CMM parameter in STAAD).

The user will also have the option to specify specific values for C1 & C2 usingthe new ‘C1’ and ‘C2’ parameters in the design input mode.

The French NA considers three separate loading conditions:

l Members with end moments

l Members with transverse loading

l Members with end moments and transverse loading.

The first two cases and its variants can be defined using with the existingCMM parameter values in STAAD.Pro. However the third condition cannot becurrently specified in the design input. Hence this implementation willintroduce two new values for CMM viz.

CMM 7:Member with varying end moments and uniform loading.

CMM 8: Member with varying end moments and central point load.

The load to moment ratio (μ) will then be used in the calculations will then beused to calculate C1 and C2 as given in section 3.5 of Annex MCR (See AnnexMCR in the NA for details).

This implementation will also introduce a new parameter ‘MU’ to be specifiedwhen using CMM = 7 or 8. The load to moment ratio (μ) to be used in thecalculations is to be input using the new ‘MU’ parameter. This implementationwill require that for the French National Annex if CMM = 7 or 8 has beenspecified, the user should also either specify a value for ‘MU’ or input thevalues for C1 and C2 using the ‘C1’ and/or ‘C2’ parameters directly.

Note: The new parameter MU will currently be applicable only in thecontext of the French NA.

2. SN030a-EN-EU – Mono-symmetrical uniform members under bending andaxial compression:

This document provides a method to evaluate the elastic critical moment(Mcr) for uniform mono symmetric sections that are symmetric about theweak axis. Hence for this implementation the elastic critical moment for ‘Tee-Sections’ will be worked out using the method in this NCCI.

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Note: Though this method could also be applicable to mono-symmetricbuilt-up sections, STAAD.Pro currently does not have a means tospecify/identify a mono-symmetric built-up section. Hence thisimplementation will use this method only for Tee-Sections.

The equation to evaluate Mcr for mono symmetric sections is given as :

The factors C1, C2 and C3 are dependent on the end conditions and loadingcriteria. This implementation will consider C1, C2 and C3 as given in thetables below:

The CMM parameter specified during design input will determine the valuesof C1, C2 and C3. The default value of CMM is 0, which considers themember as a pin ended member with UDL along its span. This NCCI does not

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however consider the “end moments and transverse loading” condition. Theuser however can use the new ‘C1’, ‘C2’ and ‘C3’ parameters to input therequired values for C1, C2 and C3 to be used in calculating Mcr.

Note: If ‘MU’ as well as C1, C2 and C3 have been specified, the programwill ignore MU and use the user input values of C1, C2 and C3. Thecurrent implementation of EC3 in STAAD.Pro obtains these values fromAnnex F of DD ENV version of 1993-1-1:1992.

Also, the NCCI document and Annex MCR of the FR-NA assume that the memberunder consideration is free to rotate on plan and that there are no warpingrestraints for the member( k = kw=1 .i.e., CMN parameter =1.0). Hence the abovemethods will be used only for members which are free to rotate on plan and whichhave no warping restraints. For members with partial or end fixities (ie, CMN = 0.5or CMN = 0.7), this implementation will fall back on to the method and coefficientsin DD ENV 1993-1-1:1992.

For all cases that are not dealt with by the National Annex (or the NCCI documents)this implementation will use the method as per the DD ENV 1993-1-1:1992 code.

The term ‘zg’ in the equation to calculate Mcr refers to the distance between thepoint of application of load on the cross section in relation to the shear center of thecross section. The value of ‘zg’ is considered positive, if the load acts towards theshear center and is negative if it acts away from the shear center. By default, theprogram will assume that the load acts towards the shear center at a distance equalto (Depth of section/2) from the shear center. The use will be allowed to modifythis value by using the ZG parameter. Specifying a value of ZG = 0 in the designinput would indicate that the load acts exactly at the shear center of the section sothat the term ‘zg’ in the equation will have a value of zero.

Note: There is a separate method specified in the NCCI document “SN006a-EN-EU” to calculate Mcr for cantilever beams. Again this document does not giveany specific formulae to evaluate the coefficients. Hence, this has not beenimplemented in STAAD.Pro.

Clause 6.3.2.3(1) – LTB for rolled sections or equivalent welded sec-tion

The FR-NA provides equations to evaluate the λLT0

and αLTfactors given in clause

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6.3.2.3

For rolled doubly symmetric sections use:

Since EN 1993-1-1:2005 limits the value of λLT0 to 0.4, this implementation willonly allow a maximum value of 0.4 for λ

LT0.

For welded doubly symmetric sections use:

For other sections

And for all sections use β = 1.0

These equations and factors are then applied to equation 6.57 of NF EN 1993-1-1to evaluate the Lateral Torsional Buckling reduction factor χ

LT.

Clause 6.3.2.3(2) – Modification factor, ‘f’ for LTB checks

The French NA specifies that the modification factor is to be obtained as per thedefault method given in EC-3. Hence this implementation will use the existingfunctionality to evaluate the correction factor ‘kc’ to be used in the modificationfactor f.

The program uses a default value of 1.0 for ‘kc’. However the user can also input acustom value of ‘kc’ by setting the design parameter ‘KC’ to the desired value. Theuser can also get the program to calculate the value of ‘kc’ automatically by settingthe value of the ‘KC’ parameter in the design input to 0. This will cause theprogram to evaluate ‘kc’ from table 6.6 of NF EN 1993-1-1:2005. This willcorrespond to the end conditions and the bending moment of the member (i.e thevalue of CMM parameter specified). For CMM = 7 the program will choose thevalue of ‘kc’ to be either 0.90 or 0.91 based on the end moment ratio. For CMM =8 the program will choose the value of ‘kc’ to be either 0.77 or 0.82 based on theend moment ratio.

An additional check will also be performed as given below:

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The French Annex specifies that the modification factor is applicable only tomembers that are free to rotate on plan (i.e., CMN =1.0). Hence for all other valuesof CMN, this implementation will ignore ‘f’ and hence will use χ

LT,mod=  χ

LT.

Clause 6.3.2.4(1) B – Slenderness for flexural buckling

Note: STAAD does not use this clause in the current implementation of EC-3.Hence this clause will be ignored for the French National Annex.

Clause 6.3.2.4(2) BModification factor ‘kfl’

Note: STAAD does not use this clause in the current implementation of EC-3.Hence this clause will be ignored for the French National Annex.

Clause 6.3.3(5) – Interaction factors kyy, kyz, kzy and kzz

The French NA recommends the use of equations in Annex A of NF EN 1993-1-1:2005 to calculate these interaction factors. The current implementation of EC3 BSin STAAD.pro uses the method in Annex B. Hence the method in Annex A will beadded into this implementation.

The NA mentions that this method can be extended to singly symmetric I-Sections(symmetric about the minor axis) if the elastic properties are used instead of theplastic properties. However since STAAD does not have a provision to specify suchsections, this case will not be considered for this implementation.

The NA also mentions that torsional flexural buckling needs to be taken intoaccount in case of mono symmetric sections. Torsional flexural buckling will needto be taken into account based on the method given in the NCCI document“SN001a-EN-EU: Critical axial load for torsional and flexural torsional bucklingmodes”. See section below for details.

The NA also recommends a lower limit as given below for the term Cmi,0 in tableA.2 of Annex A:

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Clause 6.3.1.4 - Slenderness for torsional and torsional- flexuralbuckling

Equations 6.52 and 6.53 of NF EN 1993-1-1:2005 are to be used to calculate thenon-dimensional slenderness λT,  to be used for torsional and torsional-flexuralbuckling checks. The current implementation of EC3 in STAAD.pro does not allowfor this clause as NF EN 1993-1-1:2005 does not provide equations to calculatethe elastic critical loads Ncr,T,F and Ncr,T (refer 6.3.14 of NF EN 1993-1-1:2005).

The NCCI document “SN001a-EN-EU: Critical axial load for torsional and flexuraltorsional buckling modes” provides methods to calculate the Ncr,TF and NcrTfactors and hence will to be included in this implementation of the French NA.

The critical axial load for Torsional buckling is worked out as:

where, iy and iz are the radius of gyration about the Y-Y (weak axis) and Z-Z(strong axis) respectively.

The critical axial load for Torsional-Flexural buckling is worked out as:

For details on these equations refer to the NCCI document SN001a-EN-EU.

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5B.5 (C) EC3 NA Finnish National Annex

Purpose

Adds values from the Finnish National Annex - titled National Annex to StandardSFS-EN 1993-1-1 - for use with Eurocode 3, or EN 1993-1-1:2005. The NAdocument makes small changes to the base document.

Description

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that havebeen dealt with in the Finnish National Annex (hereafter referred to as SFS-NA) andthat are relevant to the proposed implementation are:

l 3.2.1(1) Material properties

l 6.1(1) General

l 6.3.2.2 Lateral Torsional Buckling curves – General case

l 6.3.2.3(1) Lateral Torsional buckling curves for rolled or equivalent weldedsections

l 6.3.2.3(2) Modification factor calculations

l 6.3.2.4(1) B Slenderness limit λc0

l 6.3.2.4(2) B Modification factor ‘kfl’

l 6.3.3 Method for calculation interaction factors for members in combinedbending and compression

l Annex B Members in bending and axial compression

Note: Refer to the basic code (EC3) for a description of these clauses. Thesections below refer to the corresponding clauses in the Finnish-NA.

Clause 3.2.1(1) - Material Properties

The material strengths (i.e., steel grade strengths) to be used with SFS-EN 1993-1-1 are given in Table 3.1 of the code. These steel grade values are specified usingthe SGR parameter (refer to table 5B.1(B) ).

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The Finnish National Annex states in Cl. 3.1(2) that, apart from the steel gradesspecified in Table 3.1 of SFS EN 1993-1-1, the following steel grades can also beused:

l Steel grades S315MC, S355MC, S420MC and S460MC according to SFS-EN10149-2

l Steel grades S260NC, S315NC, S355NC and S420NC according to SFS-EN10149-3

These grades of steel can be specified by using the PY (Yield Strength) and FU(Ultimate Strength) parameters in STAAD.Pro. Set these parameters to therespective values as given in SFS-EN 10149-2/3 for the steel grades specifiedabove. The choice of the buckling curve to be used is based on the value of theSGR parameter specified. The output will include the appropriate yield strengthused for design.

Clause 6.1(1) – General

The partial safety factors will use the following values:

l Resistance of cross-sections - ΓM0 = 1.0

l Resistance of members to instability - ΓM1 = 1.0

l Resistance of cross sections to tension - ΓM2 = 1.25

STAAD.Pro sets the default values of the GM0, GM1 and GM2 parameters in thedesign module to the values as:

GM0 = 1.0

GM1 = 1.0

GM2 = 1.25

Note: When NA 5 has been specified.

You may override these default values and set custom values to these parameters.These parameters are reported in the design output.

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Note: If any of these parameters have been specified by the user as ‘0’,STAAD.Pro will ignore the specified value and use the default values as givenabove.

Clause 6.3.2.2 –Elastic critical moment and imperfection factors forLTB checks

The Finnish NA recommends the use of Table 6.3 and 6.4 of SFS EN 1993-1-1:2005 to calculate the imperfection factors for Lateral Torsional Buckling (LTB)checks.

The calculation of the LTB reduction factor XLT, requires the calculation of the‘Elastic Critical Buckling Moment’, Mcr. The Finnish National Annex does not specifya particular method to calculate Mcr. Hence the calculation of Mcr has been basedon the following NCCI documents:

1. SN003a-EN-EU – Elastic critical moment for Lateral torsional Buckling:

This document provides a method to calculate ‘Mcr’ specifically for doublysymmetric sections only. Hence only doubly symmetric sections will beconsidered for this method. The equation to evaluate Mcr is given in the NCCIas:

C1 and C2 are factors that depend on the end conditions and the loadingconditions of the member. The NCCI provides values for C1 and C2 for thedifferent cases as given in the tables below:

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ψ C1

+1,00 1,00

+0,75 1,14

+0,50 1,31

+0,25 1,52

0,00 1,77

-0,25 2,05

-0,50 2,33

-0,75 2,57

Table 5B.9 - Values of C1for

end moment loading (for k=1)

This NCCI considers three separate loading conditions:

l Members with end moments

l Members with transverse loading

l Members with end moments and transverse loading.

STAAD.Pro accounts for the loading condition and the bending momentdiagram through the CMM parameter.

2. SN030a-EN-EU – Mono-symmetrical uniform members under bending andaxial compression:

This document provides a method to evaluate the elastic critical moment(Mcr) for uniform mono symmetric sections that are symmetric about theweak axis. Hence, the elastic critical moment for ‘Tee-Sections’ will beworked out using the method in this NCCI.

Note: Though this method could also be applicable to mono-symmetricbuilt-up sections, STAAD.Pro currently does not have a means tospecify/identify a mono-symmetric built-up section. Hence thisimplementation will use this method only for Tee-Sections.

The equation to evaluate Mcr for mono symmetric sections is given as :

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The factors C1, C2 and C3 are dependent on the end conditions and loadingcriteria. This implementation will consider C1, C2 and C3 as given in thetables below:

The CMM parameter specified during design input will determine the values ofC1, C2 and C3. The default value of CMM is 0, which considers the member asa pin ended member with UDL along its span. This NCCI does not howeverconsider the “end moments and transverse loading” condition. The userhowever can use the new ‘C1’, ‘C2’ and ‘C3’ parameters to input the requiredvalues for C1, C2 and C3 to be used in calculating Mcr.

Note: If ‘MU’ as well as C1, C2 and C3 have been specified, the programwill ignore MU and use the user input values of C1, C2 and C3. STAAD.Proobtains these values from Annex F of DD ENV version of 1993-1-1:1992.

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Both the NCCI documents mentioned above assume that the member underconsideration is free to rotate on plan and that there are no warping restraints forthe member ( k = kw = 1.0). STAAD.Pro takes into account of the end conditionsusing the CMN parameter for EC3. A value of K = kw =1 is indicated by a value ofCMN = 1.0 in the design input. Hence the above methods will be used only formembers which are free to rotate on plan and which have no warping restraints(i.e., CMN = 1.0). For members with partial or end fixities (i.e., CMN = 0.5 or CMN= 0.7), this implementation will fall back on to the method and coefficients in DDENV 1993-1-1:1992 – Annex F.

For all cases that are not dealt with by the National Annex (or the NCCIdocuments) this implementation will use the method as per the DD ENV 1993-1-1:1992 code.

The term ‘zg’ in the equation to calculate Mcr refers to the distance between thepoint of application of load on the cross section in relation to the shear center ofthe cross section. The value of ‘zg’ is considered positive, if the load acts towardsthe shear center and is negative if it acts away from the shear center. By default,the program will assume that the load acts towards the shear center at a distanceequal to (Depth of section/2) from the shear center. The use will be allowed tomodify this value by using the ZG parameter. Specifying a value of ZG = 0 in thedesign input would indicate that the load acts exactly at the shear center of thesection so that the term ‘zg’ in the equation will have a value of zero.

Note: There is a separate method specified in the NCCI document “SN006a-EN-EU” to calculate Mcr for cantilever beams. Again this document does notgive any specific formulae to evaluate the coefficients. Hence, this has not beenimplemented in STAAD.Pro.

Clause 6.3.2.3(1) – LTB for rolled sections or equivalent welded sec-tion

The Finnish-NA provides the values for the terms λLT0

and β factors given in clause6.3.2.3(1) as follows:

For rolled doubly symmetric sections and hollow sections, use:

λLT0

=0.4 and β = 0.75

For welded doubly symmetric sections and hollow sections use:

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λLT0

= 0.2 and β = 1.0

The Finnish NA specifies the following limits for choosing the buckling curves:

Cross-section

(constant cross-section)

Limits BucklingCurve

Rolled double symmetric I- and H- sections andhot finished hollow sections.

h/b ≤2

2 <h/b<3.1

b

c

Welded double symmetric I- section and H- sec-tions and cold-formed hollow sections

h/b ≤2

2 <h/b <3.1

c

d

Table 5B.10 - Selection of lateral torsional buckling curve for cross sec-tiosn using equation (6.57)

The NA says that for all other cases the rules given in Cl 6.3.2.2 should be used.Hence even for rolled or welded doubly symmetric sections with h/b ratio ≥ 3.1,this implementation will resort to checks as per clause 6.3.2.2.

These equations and factors are then applied to equation 6.57 of SFS-EN 1993-1-1to evaluate the Lateral Torsional Buckling reduction factor χ

LT.

Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTB Reduction factor, χLT

as per Finnish NA

Clauses 6.3.2.2 and 6.3.2.3 (EN 1993-1-1:2005), both give equations to evaluatethe LTB reduction factor χ

LTto be used in eqn. 6.55 of SFS EN 1993-1-1:2005.

Cl. 6.3.2.2 uses tables 6.3 and 6.4 to choose the buckling curve and theimperfection factors to be used for calculating χ

LT. Table 6.4 specifies the choice of

buckling curves for “Rolled I Sections”, “Welded I Sections” and “Any othersections”. Cl 6.3.2.3 on the other hand uses tables 6.5 and 6.3 to choose the

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buckling curves and imperfection factors. Table 6.5 however only deals with“Rolled I Sections” and “Welded I Sections”.

Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending membersof constant cross section the value of χ

LTshould be determined from...”. Hence in

the implementation of EC3 (and the Finnish Annex) in STAAD.Pro: by default theprogram will consider clause Cl. 6.3.2.3 to evaluate χ

LT. For any case that is not

dealt with by Cl. 6.3.2.3, the program will consider Cl. 6.3.2.2 to evaluate χLT.

Cl. 6.3.2.3 in the Finnish National Annex gives equations to evaluate theimperfection factors to be used for various section types. (See above). Hence forall cases dealt with by the equations in the Finnish NA, this implementation will useCl 6.3.2.3 to evaluate χ

LT.

For any other type of cross section that is not dealt with by the National Annex orCl.6.3.2.3, the program will use Cl. 6.3.2.2 to evaluate χ

LT.

In any case, the elastic critical moment,Mcr, (used to evaluate the non dimensionalslenderness) will be worked out as given above. Since this implementation usesthe NCCIs mentioned in the sections above, only end restraint conditionscorresponding to the CMN parameter=1.0 (See section above) will be considered.For all other cases of the CMN parameter values, this implementation will use themethod specified in Annex F of DD ENV 1993-1-1:1992.

Note: If a National Annex has not been specified (i.e., NA parameter in thedesign input = 0), the program will use Cl. 6.3.2.3 only in the case of Rolled orwelded I & H Sections. For all other cases, the program will use Cl. 6.3.2.2 ofBS EN 1993-1-1:2005. Also, I sections with plates will be treated as built-upsections only if the section has been explicitly specified as a built-up section(i.e., SBLT parameter = 1.0 in design input).

Clause 6.3.2.3(2) – Modification factor, ‘f’ for LTB checks

STAAD.Pro uses the value of the modification factor f = 1.0 as given in the FinnishNA.

Clause 6.3.2.4(1) B – Slenderness for flexural buckling

Note: STAAD does not use this clause in the current implementation of EC-3.

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Hence this clause will be ignored for the Finnish National Annex.

Clause 6.3.2.4(2) B Modification factor ‘kfl’

Note: STAAD does not use this clause in the current implementation of EC-3.Hence this clause will be ignored for the Finnish National Annex.

Clause 6.3.3(5) – Interaction factors kyy, kyz, kzy and kzz

The Finnish NA recommends the use of equations in Annex A or Annex B of SFS-EN1993-1-1 to calculate these interaction factors. STAAD.Pro uses the method inAnnex B by default. This implementation of the Finnish NA will also use Annex B forCl.6.3.3 checks.

Clause 6.3.1.4 - Slenderness for torsional and torsional- flexural buck-ling

Equations 6.52 and 6.53 of SFS EN 1993-1-1:2005 are to be used to calculate thenon-dimensional slenderness λT,  to be used for torsional and torsional-flexuralbuckling checks. The current implementation of EC3 in STAAD.pro does not allowfor this clause as SFS EN 1993-1-1:2005 does not provide equations to calculatethe elastic critical loads Ncr,T,F and Ncr,T (refer 6.3.14 of SFS EN 1993-1-1:2005).

The NCCI document “SN001a-EN-EU: Critical axial load for torsional and flexuraltorsional buckling modes” provides methods to calculate the Ncr,TF and NcrTfactors and hence will to be included in this implementation of the Finnish NA.

The critical axial load for Torsional buckling is worked out as:

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where, iy and iz are the radius of gyration about the Y-Y (weak axis) and Z-Z(strong axis) respectively.

The critical axial load for Torsional-Flexural buckling is worked out as:

The program will only consider Channel Sections and Tee- sections while workingout the critical torsional and Flexural Torsional buckling loads as per Cl 6.3.1.4.For details on these equations, refer to the NCCI document SN001a-EN-EU.

5B.6 (C) EC3 NA Polish National Annex

Purpose

Adds values from the Polish National Annex - titled National Annex to StandardPN-EN 1993-1-1 - for use with Eurocode 3, or EN 1993-1-1:2005. The NAdocument makes small changes to the base document.

Description

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) thathave been dealt with in the Polish National Annex (hereafter referred to as PN-NA)and that are relevant to the proposed implementation are:

l 3.2.1(1) Material properties

l 6.1(1) General

l 6.3.2.2 Lateral Torsional Buckling curves – General case

l 6.3.2.3(1) Lateral Torsional buckling curves for rolled or equivalent weldedsections

l 6.3.2.3(2) Modification factor calculations

l 6.3.3 Method for calculation interaction factors for members in combinedbending and compression

l Annex B Members in bending and axial compression

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Note: Refer to the basic code (EC3) for a description of these clauses. Thesections below refer to the corresponding clauses in the Polish-NA.

Clause 3.2.1(1) - Material Properties

The material strengths (i.e., steel grade strengths) to be used with PN-EN 1993-1-1are given in Table 3.1 of the code. The Polish National Annex states in Cl. 3.1(2)that the steel grades to be used will be based on Table 3.1 of PN EN 1993-1-1.These steel grade values are specified using the SGR parameter (refer to table5B.1(B) ).

Clause 6.1(1) – General

The partial safety factors will use the following values:

l Resistance of cross-sections - ΓM0 = 1.0

l Resistance of members to instability - ΓM1 = 1.0

l Resistance of cross sections to tension - ΓM2 = minimum of 1.1 or 0.9 x fu/fy

STAAD.Pro sets the default values of the GM0, GM1 and GM2 parameters in thedesign module to the values as:

GM0 = 1.0

GM1 = 1.0

Note: When NA 6 has been specified.

STAAD.Pro determines the value for GM2 based on the value of the SGR designparameter or the fy and/or fu values specified using the PY and FU designparameters. If any of these parameters have not been specified, the program willuse the SGR parameter to determine fy or fu and use them to evaluate GM2. Thus,GM2 is taken as the minimum of:

l 1.1, or

l 0.9 x (fu/fy)

Where:

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fu is the ultimate steel strength

fy is the yield strength of steel

You may override these default values and set custom values to these parameters.These parameters are reported in the design output.

Note: If any of these parameters have been specified by the user as ‘0’,STAAD.Pro will ignore the specified value and use the default values as givenabove.

Clause 6.3.2.2 –Elastic critical moment and imperfection factors forLTB checks

The Polish NA recommends the use of Table 6.3 and 6.4 of PN EN 1993-1-1:2005to calculate the imperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor XLT, requires the calculation of the‘Elastic Critical Buckling Moment’, Mcr. The Polish National Annex does not specifya particular method to calculate Mcr. Hence the calculation of Mcr has been basedon the following NCCI documents:

1. SN003a-EN-EU – Elastic critical moment for Lateral torsional Buckling:

This document provides a method to calculate ‘Mcr’ specifically for doublysymmetric sections only. Hence only doubly symmetric sections will beconsidered for this method. The equation to evaluate Mcr is given in theNCCI as:

C1 and C2 are factors that depend on the end conditions and the loadingconditions of the member. The NCCI provides values for C1 and C2 for thedifferent cases as given in the tables below:

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ψ C1

+1,00 1,00

+0,75 1,14

+0,50 1,31

+0,25 1,52

0,00 1,77

-0,25 2,05

-0,50 2,33

-0,75 2,57

Table 5B.11 - Values of C1for

end moment loading (for k=1)

This NCCI considers three separate loading conditions:

l Members with end moments

l Members with transverse loading

l Members with end moments and transverse loading.

STAAD.Pro accounts for the loading condition and the bending momentdiagram through the CMM parameter.

2. SN030a-EN-EU – Mono-symmetrical uniform members under bending andaxial compression:

This document provides a method to evaluate the elastic critical moment(Mcr) for uniform mono symmetric sections that are symmetric about theweak axis. Hence, the elastic critical moment for ‘Tee-Sections’ will beevaluated using the method in this NCCI.

Note: Though this method could also be applicable to mono-symmetricbuilt-up sections, STAAD.Pro currently does not have a means tospecify/identify a mono-symmetric built-up section. Hence thisimplementation will use this method only for Tee-Sections.

The equation to evaluate Mcr for mono symmetric sections is given as :

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The factors C1, C2 and C3 are dependent on the end conditions and loadingcriteria. This implementation will consider C1, C2 and C3 as given in thetables below:

The CMM parameter specified during design input will determine the valuesof C1, C2 and C3. The default value of CMM is 0, which considers themember as a pin ended member with UDL along its span. This NCCI does nothowever consider the “end moments and transverse loading” condition. Theuser however can use the new ‘C1’, ‘C2’ and ‘C3’ parameters to input therequired values for C1, C2 and C3 to be used in calculating Mcr.

Note: If ‘MU’ as well as C1, C2 and C3 have been specified, the programwill ignore MU and use the user input values of C1, C2 and C3.

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STAAD.Pro obtains these values from Annex F of DD ENV version of1993-1-1:1992.

Both the NCCI documents mentioned above assume that the member underconsideration is free to rotate on plan and that there are no warping restraints forthe member ( k = kw = 1.0). STAAD.Pro takes into account of the end conditionsusing the CMN parameter for EC3. A value of K = kw =1 is indicated by a value ofCMN = 1.0 in the design input. Hence the above methods will be used only formembers which are free to rotate on plan and which have no warping restraints(i.e., CMN = 1.0). For members with partial or end fixities (i.e., CMN = 0.5 or CMN= 0.7), this implementation will fall back on to the method and coefficients in DDENV 1993-1-1:1992 – Annex F.

For all cases that are not dealt with by the National Annex (or the NCCI documents)this implementation will use the method as per the DD ENV 1993-1-1:1992 code.

The term ‘zg’ in the equation to calculate Mcr refers to the distance between thepoint of application of load on the cross section in relation to the shear center of thecross section. The value of ‘zg’ is considered positive, if the load acts towards theshear center and is negative if it acts away from the shear center. By default, theprogram will assume that the load acts towards the shear center at a distance equalto (Depth of section/2) from the shear center. The use will be allowed to modifythis value by using the ZG parameter. Specifying a value of ZG = 0 in the designinput would indicate that the load acts exactly at the shear center of the section sothat the term ‘zg’ in the equation will have a value of zero.

Note: There is a separate method specified in the NCCI document “SN006a-EN-EU” to calculate Mcr for cantilever beams. Again this document does not giveany specific formulae to evaluate the coefficients. Hence, this has not beenimplemented in STAAD.Pro.

Clause 6.3.2.3(1) – LTB for rolled sections or equivalent welded sec-tion

The Polish-NA provides the values for the terms λLT0

and β factors given in clause6.3.2.3(1) as follows:

For all sections, use:

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λLT0

=0.4 and β = 0.75

The Polish NA specifies the use of uses table 6.5 to work out the buckling curvesfor use in Cl. 6.3.2.3. Hence table 6.5 in PN-EN 1993-1-1 will be used for this.

These equations and factors are then applied to equation 6.57 of PN-EN 1993-1-1to evaluate the Lateral Torsional Buckling reduction factor χ

LT.

Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTB Reduction factor,χLTas per Polish NA

Clauses 6.3.2.2 and 6.3.2.3 (EN 1993-1-1:2005) both give equations to evaluatethe LTB reduction factor χ

LTto be used in eqn. 6.55 of PN EN 1993-1-1:2005.

Cl. 6.3.2.2 uses tables 6.3 and 6.4 to choose the buckling curve and theimperfection factors to be used for calculating χ

LT. Table 6.4 specifies the choice of

buckling curves for “Rolled I Sections”, “Welded I Sections” and “Any othersections”. Cl 6.3.2.3 on the other hand uses tables 6.5 and 6.3 to choose thebuckling curves and imperfection factors. Table 6.5 however only deals with“Rolled I Sections” and “Welded I Sections”.

Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending membersof constant cross section the value of χ

LTshould be determined from...”. Hence in

the implementation of EC3 (and the Polish Annex) in STAAD.Pro: by default theprogram will consider clause Cl. 6.3.2.3 to evaluate χ

LT. For any case that is not

dealt with by Cl. 6.3.2.3, the program will consider Cl. 6.3.2.2 to evaluate χLT.

Cl. 6.3.2.3 in the Polish National Annex gives equations to evaluate theimperfection factors to be used for various section types. (See above). Hence forall cases dealt with by the equations in the Polish NA, this implementation will useCl 6.3.2.3 to evaluate χ

LT.

For any other type of cross section that is not dealt with by the National Annex orCl.6.3.2.3, the program will use Cl. 6.3.2.2 to evaluate χ

LT.

In any case, the elastic critical moment,Mcr, (used to evaluate the non dimensionalslenderness) will be evaluated as given above. Since this implementation uses theNCCIs mentioned in the sections above, only end restraint conditionscorresponding to the CMN parameter=1.0 (See section above) will be considered.For all other cases of the CMN parameter values, this implementation will use themethod specified in Annex F of DD ENV 1993-1-1:1992.

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Note: If a National Annex has not been specified (i.e., NA parameter in thedesign input = 0), the program will use Cl. 6.3.2.3 only in the case of Rolled orwelded I & H Sections. For all other cases, the program will use Cl. 6.3.2.2 ofBS EN 1993-1-1:2005. Also, I sections with plates will be treated as built-upsections only if the section has been explicitly specified as a built-up section(i.e., SBLT parameter = 1.0 in design input).

Clause 6.3.2.3(2) – Modification factor, ‘f’ for LTB checks

STAAD.Pro uses the value of the modification factor f as per eqn 6.58 of PN-EN1993-1-1. The correction factor ‘kc’ will be evaluated as:

Kc = √(CmLT)

Where:

CmLT is the equivalent uniform moment factor from table B.3 of PN-EN1993-1-1. CmLT will be evaluated based on the end conditions of themember and the shape of the bending moment diagram. However, ifthe KC parameter has been used, then the program will use thespecified value.

Clause 6.3.3(5) – Interaction factors kyy, kyz, kzy and kzz

The Polish NA recommends the equations in Annex B of PN-EN 1993-1-1 tocalculate these interaction factors. The current implementation of EC3 BS inSTAAD.pro uses the method in Annex B by default. The proposed implementationof the Polish NA will also use Annex B for Cl.6.3.3 checks.

The Polish NA also gives two additional simplified checks. This implementation willprovide for these additional checks as well. However as they are intended asoptional checks, by default, the program will not perform these checks. However,the user can invoke these checks by using the PLG parameter. This parameter canhave the following values:

l PLG = 0 (default) : Ignore additional Cl. 6.3.3 checks

l PLG = 1 : Include additional Cl. 6.3.3 checks.

If the value of the PLG parameter is set to 1, the following two checks will beperformed as per Cl. NA.20.(2) and NA.20(3) respectively:

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l Cl. NA.20.(2): The following condition will be checked

n/ χ and + Cmymy/ χLT+ C mz m with ≤ 1- Δ

0(I = y or z)

where:

n = NEd/NRd

my= max M

y,Ed(+ Δ M

y, Ed)/M

y, Rd; m

z= max M

,Z Ed(+ Δ M

,

Ed)/M

Z Rd,

χ and –buckling factor,

χLT- LTB factor

Cm- moment factor from table B 3 of PN EN 1993-1-1,

Δ0-correction factor (estimation of maximum reduction) and will

be worked out as:

Δ0= 0,1 + 0,2 (w

i– 1), przy czym w

i= W

pl,i/W

el,i,

or

Δ0= 0,1 – in case of class 3 and 4 sections.

l Cl. NA.20.(3): This condition will only be checked for circular hollowsections.

n/χi+ [(k

iimi)2 + (C

mjmj)2] 1/2 ≤ 1 (i,j =y,z)

where:

k - the interaction factor from table B.1 of PN-EN 1993-1-1

and n, m, Cmj are as above.

If the PLG parameter has been set to 1, the maximum among the following ratioswill be taken as being critical for Cl 6.3.3:

6.3.3: Eqn6.61

6.3.3: Eqn6.62

NA.20(2) and

NA.20(3)

If however PLG has been set to 0 or not specified at all, the program will ignorethe last two checks in the list above.

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Clause 6.3.1.4 - Slenderness for torsional and torsional- flexural buck-ling

Equations 6.52 and 6.53 of PN EN 1993-1-1:2005 are to be used to calculate thenon-dimensional slenderness λT,  to be used for torsional and torsional-flexuralbuckling checks. The current implementation of EC3 in STAAD.pro does not allowfor this clause as PN EN 1993-1-1:2005 does not provide equations to calculate theelastic critical loads Ncr,T,F and Ncr,T (refer 6.3.14 of PN EN 1993-1-1:2005).

The NCCI document “SN001a-EN-EU: Critical axial load for torsional and flexuraltorsional buckling modes” provides methods to calculate the Ncr,TF and NcrTfactors and hence will to be included in this implementation of the Polish NA.

The critical axial load for Torsional buckling is evaluated as:

where, iy and iz are the radius of gyration about the Y-Y (weak axis) and Z-Z(strong axis) respectively.

The critical axial load for Torsional-Flexural buckling is evaluated as:

The program will only consider Channel Sections and Tee- sections while workingout the critical torsional and Flexural Torsional buckling loads as per Cl 6.3.1.4. Fordetails on these equations, refer to the NCCI document SN001a-EN-EU.

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European Codes - Timber Design Per EC 5: Part1-1

5C.1 General Comments

The Timber Design facility as per EC5 in STAAD is based on the European StandardEurocode 5: Design of Timber Structures - Part 1-1 - General - Common rules andrules for buildings. Principles of Limit States Design of Timber Structures areadopted as specified in the code.

The application is limited to the PRISMATIC rectangular shapes only. There is noEurocode-specific timber section database / library consisting of pre-definedshapes for analysis or for design. The feature of member selection is thus notapplicable to this code.

The design philosophy of this specification is based on the concept of limit statedesign. Structures are designed and proportioned taking into consideration thelimit states at which they would become unfit for their intended use. Two majorcategories of limit-state are recognized - ultimate and serviceability. The primaryconsiderations in ultimate limit state design are strength and stability, while that inserviceability is deflection. Appropriate load and resistance factors are used so thata uniform reliability is achieved for all timber structures under various loadingconditions and at the same time the chances of limits being surpassed areacceptably remote.

In the STAAD implementation, members are proportioned to resist the design loadswithout exceeding the limit states of strength, stability and serviceability.Accordingly, the most economic section is selected on the basis of the least weightcriteria as augmented by the designer in specification of allowable member depths,desired section type, or other such parameters. The code checking portion of theprogram checks whether code requirements for each selected section are met andidentifies the governing criteria.

The following sections describe the salient features of the STAAD implementationof EC 5. A detailed description of the design process along with its underlyingconcepts and assumptions is available in the specification document.

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Axes convention in STAAD and EC5

STAAD defines the major axis of the cross-section as zz and the minor axis as yy.The longitudinal axis of the member is defined as x and joins the start joint of themember to the end with the same positive direction.

EC5, however, defines the principal cross-section axes in reverse to that ofSTAAD, but the longitudinal axis is defined in the same way. Both of these axesdefinitions follow the orthogonal right hand rule.

Figure 5.6 - STAAD and EC5 axis conventions

Determination of Factors

A. Kmod – Modification factor taking into account of Load-duration (LDC) andMoisture-content (Service Class - SCL). Reference Table 3.1 of EC-5-2004.

For “Solid Timber”, the values are incorporated in the program.

B. γm– Partial factor for Material Property values. Reference Table 2.3 of EC-5-

2004.

For “Solid Timber”, the value of γm= 1.3 is incorporated in the program.

C. Kh – Size Factor.

For members, subjected to tension, whose maximum c/s dimension is lessthan the reference width in tension the characteristic strength in tension(ft0k) is to be increased by the factor Kh. 

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For members, subjected to bending, whose depth is less than reference depthin bending, the characteristic strength in bending (fmk) is to be increased bythe factor Kh.

As per clause 3.2(3) of EC 5- 2004, for rectangular solid timber with acharacteristic timber density ρ

k≤ 700 kg/m3 the reference depth in bending

or the reference width (maximum cross-sectional dimension) is 150 mm.

The value of Kh = Minimum of {(150/h) 0.2 and 1.3) for such solid timber isincorporated in the software. Please refer clause numbers 3.3 and 3.4 for thevalue of Kh for Glued laminated timber and Laminated veener lumberrespectively.

D. KC90 – Factor taking into account the load configuration, possibility ofsplitting and degree of compressive deformation.

For members, subjected to compression, perpendicular to the direction ofgrain alignment, this factor should be taken into account. Default value of 1 isused in STAAD.Pro. User may override the value. Please refer clause 6.1.5 ofEC-5-2004 in this regard.

E. Km – Factor considering re-distribution of bending stress in cross section.

For members, subjected to bending, this factor is taken into account for stresschecking. For rectangular section the value of Km is 0.7, and this value isincorporated in STAAD.Pro. User may override the value. Please refer clause6.1.6 of EC-5-2004 in this regard. 

F. Kshape – Factor depending on shape of cross section.

For members, subjected to torsional force, design torsional stress should beless than equal design shear strength multiplied by the factor Kshape. Thisfactor is determined by STAAD.Pro internally using the guidelines of clause6.1.8 of EC-5-2004.

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5C.2 Analysis Methodology

Symbol Description

St0d

Design tensile stress parallel (at zero degree) to grain alignment.

St90d

Design tensile stress perpendicular (at 90 degrees) to grain

alignment.

Sc0d

Design compressive stress parallel to grain alignment.

Sc90d

Design compressive stress perpendicular to grain alignment.

Smzd

Design bending stress about zz axis.

Smyd

Design bending stress about yy axis.

Svd

Design shear stress.

Stor_d

Design torsional stress.

Ft0d

Design tensile strength - parallel to the grain alignment.

Ft90d

Design tensile strength - perpendicular to the grain alignment.

Fc0d

Design compressive strength - parallel to the grain alignment.

Fc90d

Design compressive strength - perpendicular to the grain alignment.

Fmzd

Design bending strength - about zz-axis.

Fmyd

Design bending strength - about yy-axis.

Fvd

Design shear strength about yy axis.

RATIO Permissible ratio of stresses as input using the RATIO parameter.

 The default value is 1.

lz,lrel,z

Slenderness ratios corresponding to bending about zz axis.

ly,lrel,y

Slenderness ratios corresponding to bending about yy axis.

E0,05

Fifth percentile value of modulus of elasticity parallel to grain.

G0,05

Fifth percentile value of shear modulus parallel to grain.

Iz

Second moment of area about the strong z-axis.

Iy

Second moment of area about the weak y-axis.

Itor

Torsional moment of inertia.

fmk

Characteristic bending strength.

b, h Width and depth of beam.

Table 5C.1 - EC5 Nomenclature

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Equations for Characteristic Values of Timber Species as per Annex-A of EN338:2003

The following equations were used to determine the characteristic values:

For a particular Timber Strength Class (TSC), the following characteristic strengthvalues are required to compute the other related characteristic values.

i. Bending Strength – fm,k

ii. Mean Modulus of Elasticity in bending – E0, mean

iii. Density - ρk

SINo.

Property Symbol Wood Type

Softwood(C)

Hardwood(D)

1. Tensile Strength parallel tograin

ft,0,k

0.6 * fm,k

2. Tensile Strengthperpendicular to grain

ft,90,k

Minimum of {0.6 and(0.0015*r

k)}

3. Compressive Strengthparallel to grain

fc,0,k

5 * (fm,k

) 0.45

4. Compressive Strengthperpendicular to grain

fc,90,k

0.007*rk

0.0015*rk

5. Shear Strength fv,k

Minimum of {3.8 and(0.2*f

m,k0.8)}

6. Modulus of Elasticityparallel to grain

E0,05

0.67*E0,mean

0.84*E0,mean

7. Mean Modulus of Elasticityperpendicular to grain

E90,mean

E0,mean

/30 E0,mean

/15

8. Mean Shear Modulus Gmean

E0,mean

/16

9. Shear Modulus G0,05

E0,05

/16

The values of the characteristic strengths computed using the above equations,may differ with the tabulated values in Table-1 of EN 338:2003. However, in allsuch cases, the values obtained from the provided equations are treated as actualand is used by the program, as the values of Table-1 are based on these equations.

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Design values of Characteristic Strength

As per clause 2.4.1, Design values of a strength property shall be calculated as:

Xd= K mod·(X

k/γm)

Where:

Xdis design value of strength property

Xkcharacteristic value of strength property

γmis partial factor for material properties.

The member resistance in timber structure is calculated in STAAD according to theprocedures outlined in EC5. This depends on several factors such as crosssectional properties, different load and material factors, timber strength class, loadduration class, service class and so on. The methodology adopted in STAAD forcalculating the member resistance is explained here.

Check for Tension stresses

If the direction of applied axial tension is parallel to the direction of timber grainalignment, the following formula should be checked per Equation 6.1 of EC-52004:

St0d/Ft0d

≤ RATIO

If the direction of applied axial tension is perpendicular to the direction of timbergrain alignment, the following formula should be checked:

St90d

/Ft90d

≤ RATIO

Check for Compression stresses

If the direction of applied axial compression is parallel to the direction of timbergrain alignment, the following formula should be checked per Equation 6.2 of EC-5 2004:

Sc0d/Fc0d

≤ RATIO

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If the direction of applied axial compression is perpendicular to the direction oftimber grain alignment, the following formula should be checked per Equation 6.3of EC-5 2004:

St0d/(F

t0d·Kc90) ≤ RATIO

Check for Bending stresses

If members are under bending stresses, the following conditions should besatisfied per Equations 6.11 and 6.12 of EC-5 2004.

Note: In STAAD z-z axis is the strong axis.

(Smzd

/Fmzd

) + Km·(Smyd

/Fmyd

) ≤ RATIO

Km·(Smzd

/Fmzd

) + (Smyd

/Fmyd

) ≤ RATIO

Check for Shear stresses

Horizontal stresses are calculated and checked against allowable values perEquation 6.13 of EC-5 2004:

Svd/Fvd≤ RATIO

Check for Torsional stresses

Members subjected to torsional stress should satisfy Equation 6.14 of EC-5 2004:

Stor_d

/(Kshape·Ftor_d

) ≤ RATIO

Check for combined Bending and Axial tension

Members subjected to combined action of bending and axial tension stress shouldsatisfy Equations 6.17 and 6.18 of EC-5 2004:

Note: In STAAD z-z axis is the strong axis.

(St0d/Ft0d) + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) ≤ RATIO

(St0d/Ft0d) + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) ≤ RATIO

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Check for combined Bending and axial Compression

If members are subjected to bending and axial compression stress, Equations 6.19and 6.20 of EC-5 2004 should be satisfied:

Note: In STAAD z-z axis is the strong axis.

(Sc0d/Fc0d)2 + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) ≤ RATIO

(Sc0d/Fc0d)2 + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) ≤ RATIO

Stability check

A. Column Stability check

The relative slenderness ratios should be calculated per Equations 6.21 and6.22 of EC-5 2004.

Note: In STAAD z-z axis is the strong axis.

λrel,z

= λz/π·(S

c0k/E0,05

)1/2

λrel,y

= λy/π·(S

c0k/E0,05

)1/2

If both λrel,z

and λrel,y

are less than or equal to 0.3 the following conditionsshould be satisfied:

(Sc0d/Fc0d)2 + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) ≤ RATIO

(Sc0d/Fc0d)2 + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) ≤ RATIO

In other cases, the conditions in Equations 6.23 and 6.24 of EC-5 2004should be satisfied.

Note: In STAAD z-z axis is the strong axis.

Sc0d/(Kcz·F

c0d) + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) ≤ RATIO

Sc0d/(Kcy·F

c0d) + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) ≤ RATIO

Where (Equations 6.25 through 6.28 of EC-5 2004):

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Kcz = 1/{Kz+ [(K

z)2 - (λ

rel,z)2]1/2}

Kcy = 1/{Ky+ [(K

zy)2 - (λ

rel,y)2]1/2}

Kz = 0.5·[1 + βc·(λ

rel,z- 0.3) + (λ

rel,z)2]

Ky = 0.5·[1 + βc·(λ

rel,y- 0.3) + (λ

rel,y)2]

The value of βcincorporated in the software is the one for solid timber (i.e.,

0.2).

B. Beam Stability check

If members are subjected to only a moment about the strong axis z, thestresses should satisfy Equation 6.33 of EC-5 2004:

Smzd

/(Kcrit·Fmzd

) ≤ RATIO

Where a combination of moment about the strong z-axis and compressiveforce exists, the stresses should satisfy Equation 6.35 of EC-5 2004 (ref. toEquations 6.32 and 6.34 of the same):

[Smzd

/(Kcrit·Fmzd

)]2 + Sc0d/(Kcz·F

c0d) ≤ RATIO

Where:

Kcrit = 1.0 when λrel,m

≤ 0.75

Kcrit = 1.56 - 0.75·λrel,m

when 0.75 < λrel,m

≤ 1.4

Kcrit = 1/( λrel,m

)2 when 1.4 < λrel,m

λrel,m

= (fmk/Sm,crit

)1/2

For hardwood, use Equation 6.30 of EC-5 2004:

Sm,crit

= π·(E0,05

·Iy·G0,05

·Itor)1/2/(l

ef·W

z)

For softwood, use Equation 6.31 of EC-5 2004:

Sm,crit

= 0.78·b2·E0,05

/(h·lef)

5C.3 Design Parameters

Design parameters communicate specific design decisions to the program. They areset to default values to begin with and may be altered to suite the particularstructure.

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Depending on the model being designed, the user may have to change some or allof the parameter default values. Some parameters are unit dependent and whenaltered, the new setting must be compatible with the active “unit” specification.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified asTIMBER EC5

Design Code to follow.

See section 5.51.1 of the

Technical Reference

Manual.

ALPHA 0.0 Angle of inclination of load

to the grain alignment. (Ref.

Cl.6.1.1, Cl.6.1.2, Cl.6.1.3,

Cl.6.1.4)

l 0.0 = Load parallel to

grain,

l 90.0 = Load Per-

pendicular to grain

Table 5C.2 - Timber Design EC 5: Part 1-1 Parameters

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ParameterName

DefaultValue

Description

DFF None  “Deflection Length” / Max.

Allowable Net Final Local

Deflection.

In this case, deflection check

will be performed, if both

the parameters SERV and

DFF are present with specific

values. For appropriate

range of values, please refer

Cl.7.2 (Table 7.2)

DJ1 Start node number for a

physical member under

consideration for Deflection

Check.

DJ2 End node number for a

physical member under

consideration for Deflection

Check.

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ParameterName

DefaultValue

Description

KC90 1.0 Factor taking into account

the load configuration,

possibility of splitting and

degree of compressive

deformation. (Ref. Cl.6.1.5-

(2))

l Range: 1.0 ≤ KC90 ≤

4.0

l Other than the default

value, user may spec-

ify any value within

the range, depending

on load-position,

load-dispersion, con-

tact length at support

locations etc.

KLEF 1.0

(Member

Length)

Effective Length Factor to

check Lateral Torsional

Buckling. (Ref. Table 6.1)

Span of the beam

depending on the support

conditions and load

configurations. The user will

put the appropriate value

from the Table 6.1.

Required only for MTYP has

a value of 1 (Beam).

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ParameterName

DefaultValue

Description

KLY 1.0

(Member

Length)

Effective Length Factor for

Local-y-axis. (Ref. Cl.6.3.2),

for the computation of the

relative slenderness ratios.

KLZ 1.0

(Member

Length)

Effective Length Factor for

Local-z-axis. (Ref. Cl.6.3.2),

for the computation of the

relative slenderness ratios.

LDC 1 Load Duration Class (Ref.

Cl.2.3.1.2), required to get

the K-MOD value from Table

– 3.1.

1. Permanent action

2. Long term action

3. Medium term action

4. Short term action

5. Instantaneous action

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ParameterName

DefaultValue

Description

MTYP 0 Member Type:

Beam/Column. (Ref.

Cl.6.3.2, Cl.6.3.3)

0. Not defined by the

user – checks both

clauses (Default).

1. Beam Member

2. Column Member

This information is required

to find which stability check

will be performed as per the

Cl 6.3 according to the

Member Type.

RATIO 1.0 Permissible ratio of actual to

allowable value.

SCL 3 Service Class (Ref.

Cl.2.3.1.3)

1. = Class 1, Moisture

content <= 12%

2. = Class 2, Moisture

content <= 20%

3. = Class 3, Moisture

content > 20%

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ParameterName

DefaultValue

Description

SERV None Defines the load case

numbers – those are to be

considered for serviceability

(deflection) check.

l The list of this param-

eter must contain only

the valid load-case

numbers.

l Deflection checks will

be performed only on

those load-case

results.

l If this parameter is not

provided, then in-spite

of the presence of the

parameter DFF –the

deflection check will

NOT be performed.

TRACK 0 Degree/Level of Details of

design output results.

1. Print the design out-

put at the minimal

detail level

2. Print the design out-

put at the intermediate

detail level

3. Print the design out-

put that the maximum

detail level

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ParameterName

DefaultValue

Description

TSC 6 (C24) Timber Strength Class (Ref.

Reference EN338 – 2003)

Softwood:    1 = C14, 2 =C16, 3 = C18, 4 = C20, 5 =

C22, 6 = C24, 7 = C27, 8= C30, 9 = C35, 10 = C40,

11 = C45, 12 = C50.

Hardwood: 13 = D30, 14= D35, 15 = D40, 16 =

D50, 17 = D60, 18 = D70.

This TSC definition will

calculate thecorresponding characteristic

strength values using theequations as given in BS-EN-338, Annex - A.

5C.4 Verification  Problems

Verification Problem No. 1 - Timber Column

Problem

A Timber Column of length 1.0 meter, having c/s dimension of 73 mm X 198 mm,is subjected to an axial compressive force of 50.0 kN. Design the member for theultimate limit state.

Material properties: 

Timber class:  C24

Service classes: Class 2, moisture content ≤ 20%

Load duration classes: Medium-term 

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Cross section properties:

Length of the member is 1 m.

Rectangular cross section, b = 73 mm, h = 198 mm,

Effective cross sectional area A = 14,454 mm²,

Radius of gyration of cross section about y-axis ry= 21 mm,

Radius of gyration of cross section about z-axis rz= 57 mm,

Section modulus of cross section about z-axis:  Wz= 4.770x105mm³

Section modulus of cross section about y-axis:  Wy= 1.759x105mm³

Solution

Characteristic material properties for timber:

Modification factor Kmod = 0.80 …from table 3.1

Material factors γm= 1.30 … from table 2.3

fc0k= 21.00 N/mm²

Fc0d= (Kmod·f

c0k)/γ

m= (0.80·21.00)/1.30 = 12.92 N/mm² [Cl 2.4.1(1)P]

Cross section loads:

Fx= 50.000 kN

Compression parallel to the grain:

Sc0d= (1000xF

x)/A = (1000x50.000)/14454 = 3.46N/mm² < 12.92N/mm²

(Fc0d)

The ratio of actual compressive stress to allowable compressive strength:

Sc0d/Fc0d= 3.46 / 12.92 = 0.268 < 1.0                  [Cl. 6.1.4.(1)P]

Check for Slenderness:

Slenderness ratios:

λz= (1000/57) = 17.54

λy= (1000/21) = 47.62

E0,mean =

1.1031 kN/m2

International Design Codes Manual — 421

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As timber grade is C24 (i.e., Soft Wood)

E0,05

= 0.67·E0,mean

= 0.739 kN/m2

[Annex A,EN 338:2003]

λrel,z

= λz/π·(f

c0k/E0,05

)1/2 = 17.54/π(21.00/0.739)1/2 = 0.298

λrel,y

= λy/π·(f

c0k/E0,05

)1/2 = 47.62/π(21.00/0.739)1/2 = 0.809

Since, λrel,y

is greater than 0.3, following conditions should be satisfied:

Sc0d/(Kcz·F

c0d) + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) ≤ RATIO

Sc0d/(Kcy·F

c0d) + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) ≤ RATIO

Where:

Kz = 0.5·[1 + βc·(λ

rel,z- 0.3) + (λ

rel,z)2] = 0.50·[1 + 0.2(0.298 - 0.3)

+ (0.298)2] = 0.541

Ky = 0.5·[1 + βc·(λ

rel,y- 0.3) + (λ

rel,y)2] = 0.50·[1 + 0.2(0.809 - 0.3)

+ (0.809)2] = 0.878

Kcz = 1/{Kz+ [(K

z)2 - (λ

rel,z)2]1/2} = 1/{0.541 + [(0.541)2 - (0.298)2]1/2}=

1.008

Kcy = 1/{Ky+ [(K

zy)2 - (λ

rel,y)2]1/2} = 1/{0.878 + [(0.878)2 - (0.809)2]1/2}

= 0.820

For Rectangular cross section Km = 0.70. The member is subjected toCompression only, so actual bending stress is zero.

Sc0d/(Kcz·F

c0d) + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) = 3.46/(1.008·12.92)+ 0.0 + 0.0 = 0.268 + 0.0 + 0.0 = 0.266

Sc0d/(Kcy·F

c0d) + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) = 3.46 /(0.820·12.92)+ 0.0 + 0.0 = 0.326 + + 0.0 + 0.0 = 0.326

Hence the critical ratio is 0.326 < 1.0 and the section is safe.

422— STAAD.Pro

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Comparison

Source Critical Ratio (Cl. 6.3.2)

Reference 0.326

STAAD.Pro 0.327

Difference Negligible

Table 5C.3 - EC 5: Part 1-1 Verification Problem 1

Input File

The following file is included AS C:\SPROV8I\STAAD\EXAMP\EUR\EC5 VER1.STD.

STAAD SPACE

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 1.0 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC WOOD

E 1.10316E+007

POISSON 0.15

DENSITY 0.00231749

ALPHA 5.5E-006

END DEFINEMATERIAL

CONSTANTS

MATERIALWOODMEMB 1

MEMBER PROPERTY

1 PRIS YD 0.198 ZD 0.073

SUPPORTS

International Design Codes Manual — 423

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1 FIXED

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

JOINT LOAD

2 FX -50

PERFORMANALYSIS

PARAMETER

CODE TIMBER EC5

ALPHA 0 ALL

LDC 3 ALL

SCL 2 ALL

TSC 6 ALL

TRACK 2 ALL

CHECK CODE ALL

FINISH

Output

The member checking part of the output file:

STAAD.Pro CODE CHECKING - (EC5 )***********************

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 PRIS ZD = 0.073 YD = 0.198PASS CL.6.3.2 0.327 1

50.00 C 0.00 0.00 0.0000|-------------------------------------------------------------------

-------|| AX = 0.01 IY = 0.00 IZ = 0.00

|| LEZ = 1.00 LEY = 1.00

||

|

424— STAAD.Pro

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| ALLOWABLE STRESSES: (NEW MMS)|

| FBY = 14.769 FBZ = 14.769|

| FC = 12.859|

| ACTUAL STRESSES : (NEW MMS)|

| fby = 0.000 fbz = 0.000|

| fc = 3.459|

|--------------------------------------------------------------------------|

Verification Problem No. 2

Problem

A Timber Column of length 1.0 meter, having c/s dimension of 73 mm X 198 mm, issubjected to an axial compressive force of 5.0 kN and moments of 2.0 kN.m and1.0 kN.m about its major and minor axes respectively. Design the member for theultimate limit state.

Material properties:

Timber Strength Class:  C24

Service classes: Class 2, moisture content <=20%

Load duration: Medium-term

Cross section properties:

Length of the member is 1 m.

Rectangular cross section, b = 73 mm, h = 198 mm,

Effective cross sectional area A = 14454 mm²,

Radius of gyration of cross section about y-axis ry= 21 mm,

Radius of gyration of cross section about z-axis rz= 57 mm,

Section modulus of cross section about z-axis:  Wz= 4.770x105mm³

Section modulus of cross section about y-axis:  Wy= 1.759x105mm³

International Design Codes Manual — 425

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Solution

Characteristic material properties for timber:

Modification factor Kmod = 0.80 …from table 3.1

Material factors γm= 1.30 … from table 2.3

fc0k= 21.00 N/mm²

E0,05

= 7370 N/mm2

Fc0d= (Kmod·f

c0k)/γ

m= (0.80·21.00)/1.30 = 12.92 N/mm² [Cl 2.4.1(1)P]

fmyk

= 24.00 N/mm²

Fmyd

= Kmod·fmyk

/γm= (0.80x24.00)/1.30 = 14.77N/mm²

fmzk

= 24.00 N/mm²

Fmzd

= Kmod·fmzk

/γm= (0.80x24.00)/1.30 = 14.77N/mm²

Cross section loads:

Fx= 5.000 kN

Mz= 2.000 kN·m

My= 1.000 kN·m

Check for Slenderness:

Slenderness ratios:

λz= (1000/57) = 17.54

λy= (1000/21) = 47.62

λrel,z

= λz/π·(f

c0k/E0,05

)1/2 = 17.54/π(21.00/7370)1/2 = 0.298

λrel,y

= λy/π·(f

c0k/E0,05

)1/2 = 47.62/π(21.00/7370)1/2 = 0.809

Since, λrel,y

is greater than 0.3, following conditions should be satisfied [Cl6.3.2.3]:

Sc0d/(Kcz·F

c0d) + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) ≤ RATIO

Sc0d/(Kcy·F

c0d) + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) ≤ RATIO

Where:

426— STAAD.Pro

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Page 437: International Codes v8i

Kz = 0.5·[1 + βc·(λ

rel,z- 0.3) + (λ

rel,z)2] = 0.50·[1 + 0.2(0.298 - 0.3)

+ (0.298)2] = 0.541

Ky = 0.5·[1 + βc·(λ

rel,y- 0.3) + (λ

rel,y)2] = 0.50·[1 + 0.2(0.809 - 0.3)

+ (0.809)2] = 0.878

Kcz = 1/{Kz+ [(K

z)2 - (λ

rel,z)2]1/2} = 1/{0.541 + [(0.541)2 - (0.298)2]1/2}=

1.008

Kcy = 1/{Ky+ [(K

zy)2 - (λ

rel,y)2]1/2} = 1/{0.878 + [(0.878)2 - (0.809)2]1/2}

= 0.820

For Rectangular cross section Km = 0.70.

Sc0d= (1000·F

x/A) = (1000·5.000)/14454 = 0.35 N/mm²

Smzd

= (106·Mz)/W

z= (106·2.000)/(4.770x105) = 4.19 N/mm²

Smyd

= (106·My)/W

y= (106·1.000)/(1.759x105) = 5.69 N/mm²

Combined stress ratio:

Sc0d/(Kcz·F

c0d) + (S

mzd/Fmzd

) + Km·(Smyd

/Fmyd

) = 0.35/(1.008·12.92)+ 4.19/14.77 + 0.70(5.69/14.77) = 0.027 + 0.283 + 0.269 = 0.266

Sc0d/(Kcy·F

c0d) + Km·(S

mzd/Fmzd

) + (Smyd

/Fmyd

) = 0.35 /(0.820·12.92)+ 0.70(4.19/14.77) + 5.69/14.77 = 0.033 + 0.385 + 0.198 = 0.616

Hence the critical ratio is 0.616 < 1.0 and the section is safe.

Comparison

Source Critical Ratio (Cl. 6.3.2)

Reference 0.616

STAAD.Pro 0.616

Difference None

Table 5C.4 - EC 5: Part 1-1 Verification Problem 2

Input File

The following file is included AS C:\SPROV8I\STAAD\EXAMP\EUR\EC5 VER2.STD.

International Design Codes Manual — 427

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STAAD SPACE

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 1 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC WOOD

E 1.10316E+007

POISSON 0.15

DENSITY 0.00231749

ALPHA 5.5E-006

END DEFINEMATERIAL

CONSTANTS

MATERIALWOODMEMB 1

MEMBER PROPERTY

1 PRIS YD 0.198 ZD 0.073

SUPPORTS

1 FIXED

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

JOINT LOAD

2 FY -5.0 MX 1.0 MZ 2.0

PERFORMANALYSIS

PARAMETER

CODE TIMBER EC5

ALPHA 0 ALL

LDC 3 ALL

SCL 2 ALL

TSC 6 ALL

428— STAAD.Pro

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TRACK 2 ALL

CHECK CODE ALL

FINISH

Output

The member checking part of the output file:

STAAD.Pro CODE CHECKING - (EC5 )***********************

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 PRIS ZD = 0.073 YD = 0.198PASS CL.6.3.2 0.616 15.00 C 1.00 -2.00 0.0000

|--------------------------------------------------------------------------|| AX = 0.01 IY = 0.00 IZ = 0.00

|| LEZ = 1.00 LEY = 1.00

||

|| ALLOWABLE STRESSES: (NEW MMS)

|| FBY = 14.769 FBZ = 14.769

|| FC = 12.859

|| ACTUAL STRESSES : (NEW MMS)

|| fby = 5.686 fbz = 4.193

|| fc = 0.346

||--------------------------------------------------------------------

------|

International Design Codes Manual — 429

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430— STAAD.Pro

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Section 6

Egyptian Codes

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432— STAAD.Pro

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Egyptian Codes - Concrete Design Per EgyptianCode - ECCS203

6A.1 Design Operations

STAAD has the capability of performing design of concrete beams, columns, andslabs according to 2004 revision of ECCS 203. Given the width and depth of asection, STAAD will calculate the required reinforcement to resist the forces andmoments.

Note: Design per ECCS203 is performed using the RC Designer Module. SelectECCS203 as the Design Code for a Design Brief.

6A.2 Member  DimensionsConcrete members which will be designed by the programmust have certainsection properties input under the MEMBER PROPERTY command. The followingexample shows the required input:

UNIT MM

MEMBER PROPERTY

1 3 TO 7 9 PRISM YD 450. ZD 250.

11 13 PR YD 350.

6A.3 Design  Parameters

The program contains a number of parameters which are needed to perform thedesign. Default parameter values have been selected such that they are frequentlyused numbers for conventional design requirements. These values may be changedto suit the particular design being performed. The following Beam Design Briefcontains a complete list of the available parameters and their default values.

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Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

6A.4 Slenderness  Effects  and  Analysis  Con-siderations

STAAD provides the user with two methods of accounting for the slendernesseffects in the analysis and design of concrete members. The first method isequivalent to the procedure presented in ECCS203-2004 equation 4-11. In thissection, the code recognizes that additional moments induced by deflection arepresent and states that these 'secondary' moments are accounted for by the designformula in equation 6-38, 6-37 etc. This is the method used in the design forconcrete in STAAD.

Alternatively STAAD houses a PDELTA ANALYSIS facility, which allows the effectsof these second order moments to be considered in the analysis rather than thedesign. In a PDELTA analysis, after solving the joint displacements of thestructure, the additional moments induced in the structure are calculated. Thesecan be compared to those calculated using the formulation of ECCS203-2004.

434— STAAD.Pro

Egyptian Codes - Concrete Design Per Egyptian Code - ECCS203

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6A.5 Beam  Design

Beams are designed for flexure, shear and torsion. For all these forces, all activebeam loadings are pre scanned to identify the critical load cases at differentsections of the beams. The total number of sections considered is 13(e.g., 0., .1,.2, .25, .3, .4, .5, .6, .7, .75, .8, .9 and 1). All of these sections are scanned todetermine the design force envelopes.

Design  for  Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) andhogging (creating tensile stress at the top face) moments are calculated for allactive load cases at each of the above mentioned sections. Each of these sections isdesigned to resist both of these critical sagging and hogging moments. Currently,design of singly reinforced sections only is permitted. If the section dimensions areinadequate as a singly reinforced section, such a message will be permitted in theoutput. Flexural design of beams is performed in two passes. In the first pass,effective depths of the sections are determined with the assumption of single layerof assumed reinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database in singleor multiple layers. The entire flexure design is performed again in a second passtaking into account the changed effective depths of sections calculated on the basisof reinforcement provided after the preliminary design. Final provisions of flexuralreinforcements are made then. Efforts have been made to meet the guideline forthe curtailment of reinforcements as per ECCS203-2004. Although exactcurtailment lengths are not mentioned explicitly in the design output (finally whichwill be more or less guided by the detailer taking into account of other practicalconsideration), user has the choice of printing reinforcements provided by STAADat 13 equally spaced sections from which the final detailed drawing can beprepared.

Design  for  Shear

Shear reinforcement is calculated to resist both shear forces and torsionalmoments. Shear design is performed at 13 equally spaced sections (0.to 1.) for themaximum shear forces amongst the active load cases and the associated torsionalmoments. Shear capacity calculation at different sections without the shearreinforcement is based on the actual tensile reinforcement provided by STAAD

International Design Codes Manual — 435

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program. Two-legged stirrups are provided to take care of the balance shearforces acting on these sections.

The following represents a sample Beam Design Output:

6A.6 Column  Design

Columns are designed for axial force and biaxial bending at the ends. All activeloadings are tested to calculate reinforcement. The loading which producesmaximum reinforcement is called the critical load and is displayed. Therequirements of ECCS203-2004 equation 6-37,6-38,6-41 etc are followed, withthe user having control on the effective length parameters. Bracing conditions arecontrolled by using the BRACE parameter. The program will then decide whetheror not the column is short or slender and whether it requires additional momentcalculations.

436— STAAD.Pro

Egyptian Codes - Concrete Design Per Egyptian Code - ECCS203

Page 447: International Codes v8i

The following represents a sample Column Design output:

International Design Codes Manual — 437

Page 448: International Codes v8i

The following represents a sample Shear Design Output:

438— STAAD.Pro

Egyptian Codes - Concrete Design Per Egyptian Code - ECCS203

Page 449: International Codes v8i

International Design Codes Manual — 439

Page 450: International Codes v8i

440— STAAD.Pro

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Egyptian Codes - Steel Design Per EgyptianCode # 205

6B.1 General Comments

This section presents some general statements regarding the implementation of the2001 revision of the Egyptian code of practice for structural steel construction andbridges Code No. 205 (Min Dec #279/2001) design in STAAD. The designphilosophy and procedural logistics for member selection and code checking arebased upon the principles of allowable stress design. Two major failure modes arerecognized: failure by overstressing and failure by stability considerations.

The flowing sections describe the salient features of the allowable stresses beingcalculated and the stability criteria being used. Members are proportioned to resistthe design loads without exceeding the allowable stresses and the most economicsection is selected on the basis of least weight criteria. The code checking part ofthe program checks stability and strength requirements and reports the criticalloading condition and the governing code criteria. It is generally assumed that theuser will take care of the detailing requirements like provision of stiffeners andcheck the local effects such as flange buckling and web crippling.

Note: Design per Code No. 205 is performed using the User Interface SteelDesign mode. Select EGPT205-2001 as theDesign Code in the Brief Detailsdialog.

6B.2 Allowable  Stresses

The member design and code checking in STAAD are based upon the allowablestress design method as per Egyptian Code No. 205, It is a method forproportioning structural members using design loads and forces, allowablestresses, and design limitations for the appropriate material under serviceconditions. It would not be possible to describe every aspect of Egyptian Code: 205in this manual. This section, however, will discuss the salient features of theallowable stresses specified by Egyptian Code: 205 and implemented in STAAD.Appropriate sections of Egyptian Code: 205 will be referenced during thediscussion of various types of allowable stresses.

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6B.2.1   Axial  Stress

Tensile Stress

The allowable tensile stress, as calculated in STAAD as per Egyptian Code: 205 isdescribed below.

The estimated stress on the net effective sectional area in various members,multiplied by the appropriate factor of safety shall not exceed minimumguaranteed yield stress of the material.

The permissible stress in axial tension, σatin MPa on the net effective area of the

sections shall not exceed: Clause: 2.6.2

Ft= 0.58·f

y

Where:

fy= minimum yield stress of steel in Mpa

Compressive Stress

Allowable compressive stress on the gross section of axially loaded compressionmembers shall not exceed the permissible stress calculated based on the followingformula: (Clause: 2.6.4)

For all grade of steel:

For λ = kl/r ≤ 100

Fc= 7500/λ2

Where:

Fc= Permissible stress in axial compression, in Mpa

fy= Yield stress of steel, in Mpa

442— STAAD.Pro

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λ = l/r = Slenderness ratio of the member, ratio of the effective lengthto appropriate radius of gyration

6B.2.2   Bending  Stress

The allowable bending stress in a member subjected to bending is calculated basedon the following formula: (Clause: 2.6.5)

The laterally unsupported length (Lu) of the compression flange is limited by

Lu= 20·b

f/fy

Fbt or F

bc =  0.64·f

y

Clause 2.6.5.5 Tension Fbt

Fbt= 0.58·F

y

Clause 2.6.5.5 Compression Fbc

I. Compression flange is braced laterally at intervals exceeding Lu, the allowable

bending stress in compression Fbcwill be taken as follows.

i. For shallow thick flanged sections, where approximately tf·Lu/(b

f·d) > 4

the lateral tensional buckling stress is governed by the torsion strengthgiven by:

Fltb1

= [800/(Lud/Af)]·C

b≤ 0.58·F

y

ii. For Deep flanged sections, where approximately tf·Lu/(b

f·d) > 4 the

lateral torsional buckling stress governed by the buckling strengthgiven by:

a. When Lu/rT≤ 84(C

b/Fy)1/2, then

F1tb2

= 0.58·Fy

b. When 84(Cb/Fy)1/2 < L

u/rT≤ 188(C

b/Fy)1/2, then

c. When Lu/rT> 188(C

b/Fy)1/2, then

F1tb2

= [1200/(Lu/rT)2]C

b≤ 0.58·F

y

Where:

International Design Codes Manual — 443

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Lu= Effective laterally unsupported length of compression

flange.

k  = Effective length factor 

rT= radius of gyration about minor axis of a section

compressing the compression web area (in cms)

bf = Compression flange width

d  = Total depth

Cb= Coefficient depending on the type of load and support

conditions as given in table 2.2

I. Compression on extreme fibers of channels bent about their major axis

Fltb= [800/(L

ud/A

f)]·C

b≤ 0.58·F

y

Where:

Fbt= Bending stress in tension

Fbc= Bending stress in compression

fy= Yield stress of steel, in MPa

6B.2.3   Shear Stress

Allowable shear stress calculations are based on Section 2.6.3 of Egyptian code205. For shear on the web, the gross section taken into consideration consists ofthe product of the total depth and the web thickness.

qall= 0.35F

y

Where:

qall= Allowable shear stress

6B.2.4   Combined  Stress

Members subjected to both axial and bending stresses are proportionedaccordingly to following

444— STAAD.Pro

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Page 455: International Codes v8i

Axial Compression and Bending

All the members subjected to bending and axial compression are required to satisfythe equation of section 2.6.7.1

Where:

fca= Actual compression stress

Fc= Allowable compressive stress, clause 2.6.4

fbcx, fbcy

= Actual Bending stress about x and y-axes respectively.

Fbcx, Fbcy

= Allowable compressive bending stress, clause 2.6.5

FEx, FEy= Euler stress in t/cm2

Cm= Moment modification factor

Axial Tension and Bending

All the members subject to bending and axial tension are required to satisfy theequation of section 2.6.7.2

6B.3 Stability Requirements

Slenderness ratios are calculated for all members and checked against theappropriate maximum values. Table 5.1 of Egyptian code #205: summarizes themaximum slenderness ratios for different types of members. In STAADimplementation of Egyptian code #205, appropriate maximum slenderness ratiocan be provided for each member. If no maximum slenderness ratio is provided,

International Design Codes Manual — 445

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compression members will be checked against a maximum value of 180 andtension members will be checked against a maximum value of 300

6B.4 Code Checking

The purpose of code checking is to verify whether the specified section is capableof satisfying applicable design code requirements. The code checking is based onthe Egyptian code #205 requirements. Forces and moments at specified sectionsof the members are utilized for the code checking calculations. Sections may bespecified using the BEAM parameter or the SECTION command. If no sections arespecified, the code checking is based on forces and moments at the member ends.

The code checking output labels the members as PASSed or FAILed. In addition,the critical condition, governing load case, location (distance from the start) andmagnitudes of the governing forces and moments are also printed out.

6B.5 Member Selection

STAAD is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section,that is, the lightest section, which satisfies the applicable code requirements. Thesection selected will be of the same type (I-Section, Channel etc.) as originallyspecified by the user. Member selection may be performed with all types of steelsections and user provided tables. Selection of members, whose properties areoriginally provided from user specified table, will be limited to sections in the userprovided table. Member selection can not be performed on members whose crosssectional properties are specified as PRISMATIC.

The process of MEMBER SELECTION may be controlled using the parameters listedin Table 6B.1. It may be noted that the parameters DMAX and DMIN may be used tospecify member depth constraints for selection. If PROFILE parameter is provided,the search for the lightest section is restricted to that profile. Up to three (3)profiles may be provided for any member with a section being selected from eachone.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

446— STAAD.Pro

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6B.6 Tabulated Results of Steel Design

For code checking or member selection, the program produces the result in atabulated fashion as well as step by step procedure.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Design of Member No. 1 As Per Egyptian Steel Code 205

6B.7 Design Parameters

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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Parameter Name Default Value Description

CB Member length Coefficient dependingon the type of load andconditions as g.

BEAM 3.0 Location of sectionforce calculations:

0.0 = design onlyfor endmomentsand those atlocationsspecified bytheSECTIONcommand.

1.0 =calculatesectionforces attwelfthpoints alongthe beam,design ateachintermediatelocation andreport thecriticallocationwhere ratioismaximum.

CMY

CMZ

0.85 for sidesway andcalculated for no

sidesway

Cm value in local y & zaxes

Table 6B.1 - Egyptian Steel Design Code #205 Parameters

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Parameter Name Default Value Description

DFF None(Mandatory fordeflection check)

"Deflection Length" /Maxm. allowable localdeflection

DMAX 100.0 cm. Maximum allowabledepth.

DMIN 0.0 cm. Minimum allowabledepth.

FYLD 250 MPA

(36.25 KSI)

Yield strength of steel.

MAIN 180 (Comp. Memb.) Allowable Kl/r forslenderness calculationsfor compressionmembers.

NSF 1.0 Net section factor fortension members.

PROFILE - Used to search for thelightest section for theprofile(s) specified formember selection. SeeSection 5.48.1 of theTechnical ReferenceManual for details. 

RATIO 1.0 Permissible ratio of theactual to allowablestresses.

SSY 0.0 Sidesway

0.0 =Sidesway inlocal y-axis.

1.0 = Nosidesway

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Parameter Name Default Value Description

SSZ 0.0 Same as above exceptin local z-axis.

TMAIN 300 (Tension Memb) Allowable Kl/r forslenderness calculationsfor tension members.

WELD 2 Design for weld:

1 = Weldfor Closedsections

2 = Weldfor Opensections

WMIN Minimum welding thick-ness.

WSTR 0.4 Fyld Absolute weldingstress.

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Section 7

French Codes

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French Codes - Concrete Design per B.A.E.L7A.1 Design Operations

STAAD has the capabilities for performing design of concrete beams, columns, andslabs according to the 1991 edition of Béton Armé aux États Limites (hereafterreferred to as BAEL). Given the width and depth (or diameter for circular columns)of a section, STAAD will calculate the required reinforcing to resist the various inputloads.

Design per B.A.E.L. is invoked by using the CODE BAEL command.

7A.2 Design Parameters

The program contains a number of parameters which are needed to perform designper B.A.E.L. These parameters not only act as a method to input required data forcode calculations but give the engineer control over the actual design process.Default values, of commonly used numbers in conventional design practice, havebeen used for simplicity. Table 7A.1 contains a complete list of available parametersand their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE BAEL Design Code to follow.

See section 5.52.2 of the TechnicalReference Manual.

CLEAR * 20mm

Clearance of reinforcing bar. Value isautomatically set to 20 mm for C35 andhigher.

DEPTH YD Depth of concrete member. This valuedefaults to YD as provided underMEMBER PROPERTIES.

Table 7A.1 - French Concrete Design B.A.E.L. Parameters

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ParameterName

DefaultValue

Description

EFACE *0.0 Face of Support Location at end of beam.

Note: Both SFACE and EFACE areinput as positive numbers.

FC * 30 N/mm2

Concrete Yield Stress.

FYMAIN * 300N/mm2

Yield Stress for main reinforcing steel.

FYSEC * 300N/mm2

Yield Stress for secondary reinforcingsteel.

MAXMAIN 50 mm Maximummain reinforcement bar size.(8mm - 60mm).

MINMAIN 8 mm Minimummain reinforcement bar size.(8mm - 60mm).

MINSEC 8 mm Minimum secondary reinforcement barsize. (8mm - 60mm).

MMAG 1.0 A factor by which the design momentswill be magnified.

SFACE *0.0 Face of support location at start of beam.Only considers shear - use MEMBEROFFSET for bending.

NSECTION 10 Number of equally-spaced sections to beconsidered in finding critical moments forbeam design.

TRACK 0.0 Critical Moment will not be printed outwith beam design report. A value of 1.0will mean a print out.

WIDTH ZD Width of the concrete member. This valuedefaults to ZD as provided underMEMBER PROPERTIES.

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* These values must be provided in the units currently being used for input.

7A.3  Slenderness  Effects  and  Analysis  Con-sideration

STAAD provides the user two methods of accounting for the slenderness effect inthe analysis and design of concrete members. The first method is a procedurewhich takes into account second order effects. Here, STAAD accounts for thesecondary moments, due to axial loads and deflections, when the PDELTAANALYSIS command is used. STAAD, after solving for the joint displacements ofthe structure, calculates the additional moments induced in the structure.Therefore, by using PDELTA ANALYSIS, member forces are calculated which willrequire no user modification before beginning member design.

The second method by which STAAD allows the user to account for the slendernesseffect is through user supplied moment magnification factors. Here the userapproximates the additional moment by supplying a factor by which moments willbe multiplied before beginning member design.

7A.4 Member Dimensions

Concrete members that are to be designed by STAAD must have certain sectionproperties input under the MEMBER PROPERTIES command. The followingexample demonstrates the required input:

UNIT MM

MEMBER PROPERTIES

1 3 TO 7 9 PRISM YD 450 ZD 300.

11 13 PR YD 300.

In the above input, the first set of members are rectangular (450 mm depth and300 mmwidth) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with a 300 mm diameter. Note that area(AX) is not provided for these members. If shear areas (AY & AZ) are to beconsidered in analysis, the user may provide them along with YD and ZD. Also notethat moments of inertia may be provided, but if not provided, the program willcalculate values from YD and ZD.

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7A.5 Beam Design

Beam design includes both flexure and shear. For both types of beam action, allactive beam loadings are scanned to create moment and shear envelopes, andlocate critical sections. The total number of sections considered is twelve, unlessthat number is redefined with the NSECTION parameter. From the critical momentvalues, the required positive and negative bar pattern is developed, with cut-offlengths calculated to include required development length.

Shear design includes critical shear values plus torsional moments. From thesevalues, stirrup sizes are calculated with proper spacing. The stirrups are assumedto be U-shaped for beams with no torsion, and closed hoops for beams subject totorsion.

Example of Input Data for Beam Design:

UNIT NEWTON MMS

START CONCRETEDESIGN

CODE BAEL

FYMAIN 415 ALL

FYSEC 415 ALL

FC 35 ALL

CLEAR 25 MEM2 TO6

MAXMAIN 40 MEMB 2 TO 6

SFACE 100 MEMB 7 TO 9

EFACE 100 MEMB 7 TO 9

TRACK 1.0 MEMB 2 TO 6

TRACK 2.0 MEMB 7 TO 9

DESIGN BEAM 2 TO9

END CONCRETEDESIGN

7A.6 Column Design

Columns are designed for axial force and biaxial moments at the ends. All activeloadings are tested to calculate reinforcement. The loading which producesmaximum reinforcement is called the critical load. Column design is done for

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square, rectangular, and circular sections. For rectangular and square sections, thereinforcement is always assumed to be equally distributed on each side. Thatmeans the total number of bars will always be a multiple of four (4). This may causeslightly conservative results in some cases.

Example of Input Data for Column Design:

UNIT NEWTON MMS

START CONCRETEDESIGN

CODE BAEL

FYMAIN 415 ALL

FC 35 ALL

CLEAR 25 MEMB 2 TO 6

MMAG 1.5 MEMB 4 5

MAXMAIN 40 MEMB 2 TO 6

DESIGN COLUMN 2 TO6

END CONCRETEDESIGN

7A.7 Slab/Wall Design

Slab and walls are designed per BAEL 1983 specifications. To design a slab or wall,it must be modeled using finite elements. The command specifications are inaccordance with Chapter II, section 6.40.

Elements are designed for the moments Mx and My. These moments are obtainedfrom the element force output (see Section 3.8 of the Technical Reference Manual).The reinforcement required to resist Mx moment is denoted as longitudinalreinforcement and the reinforcement required to resist My moment is denoted astransverse reinforcement. The parameters FYMAIN, FC, and CLEAR listed in Table7A.1 are relevant to slab design. Other parameters mentioned in Table 7A.1 are notapplicable to slab design.

Figure 7.1 - Element moments: Longitudinal (L) and Transverse (T)

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Example of Input Data for Slab/Wall Design:

UNIT NEWTON MMS

START CONCRETEDESIGN

CODE BAEL

FYMAIN 415 ALL

FC 25 ALL

CLEAR 40 ALL

DESIGN ELEMENT 15 TO 20

END CONCRETEDESIGN

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French Codes - Steel Design per the FrenchCode

7B.1 General Comments

The STAAD implementation of French Steel Design is based the 1977 edition ofCentre Technique Industriel de la Construction Metallique (hereafter referred to asCM66) publication entitled "Design Rules for Structural Steelwork."

The design philosophy embodied in this specification is based on the concept oflimit state design. Structures are designed and proportioned according to the limitstates of which they would become unfit for their intended use. Two majorcategories of limit-states are recognized: ultimate and serviceability. The primaryconsiderations in ultimate limit state design are strength and stability; that inserviceability is deflection. Appropriate load and resistance factors are used so thatuniform reliability is achieved for all steel structures under various loadingconditions and at the same time the chances of limits being surpassed areacceptably remote.

In the STAAD implementation, members are proportioned to resist the design loadswithout exceeding the limit states of strength, stability and serviceability.Accordingly, the most economic section is selected on the basis of the least weightcriteria, as augmented by the designer in specification of allowable member depths,desired section type, or other related parameters. The code checking portion of theprogram verifies that code requirements for each selected section are met and alsoidentifies the governing criteria.

The next few sections describe the salient features of STAAD implementation of"Design Rules for Structural Steelwork." A detailed description of the designprocess, along with its underlying concepts and assumptions, is available in thespecification document.

7B.2 Basis  of  Methodology

The "Design Rules for Structural Steelwork (Revision 80)" permits the usage ofelastic analysis. Thus, in STAAD, linear elastic analysis method is used to obtain theforces and moments in the members. However, strength and stabilityconsiderations are based on the principles of plastic behavior. Axial compressionbuckling and lateral torsional buckling are taken into consideration for calculation

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of axial compression resistance and flexural resistance of members. Slendernesscalculations are made and overall geometric stability is checked for all members.

7B.3 Member  Capacities

The member strengths are calculated in STAAD according to the proceduresoutlined in section 4 of this specification. Note that the program automaticallyconsiders co-existence of axial force, shear and bending in calculating sectioncapacities.

For axial tension capacity, procedures of section 4.2 are followed. For axialcompression capacity, formulas of section 5.3 are used.

Moment capacities about both axes are calculated using the procedures of sections4.5 and 4.6. Lateral torsional buckling is considered in calculating ultimatetwisting moment per section 5.22 of the specification. The parameter UNL (seeTable 7B.1) must be used to specify the unsupported length of the compressionflange for a laterally unsupported member. Note that this length is also referred toas twisting length.

7B.4 Combined  Axial  Force  and  Bending

The procedures of sections 4.55 and 5.32 are implemented for interaction of axialforces and bending. Appropriate interaction equations are used and the governingcriterion is determined.

7B.5 Design  Parameters

The design parameters outlined in Table 7B.1 may be used to control the designprocedure. These parameters communicate design decisions from the engineer tothe program, thus allowing the engineer to control the design process to suit anapplication's specific needs.

The default parameter values have been selected as frequently used numbers forconventional design. Depending on the particular design requirements, some orall of these parameter values may be changed to exactly model the physicalstructure.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CODE FRENCH Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM 0.0 0.0 =  design only for endmoments and those at locationsspecified by SECTION command.

1.0 =  calculate moments at tenthpoints long the beam, and usemaximum Mz for design.

C1 1.0 Parameter used in clause 5.21 inthe calculation of M(D), the criticaltwisting moment and as shown inCM 66 Addendum 80, table 5,usual range from 0.71 to 4.10

C2 1.0 Parameter used in clause 5.21 inthe calculation of M(D), the criticaltwisting moment and as shown inCM 66 Addendum 80, table 5,usual range from 0.0 to 1.56

DFF None(Mandatoryfordeflectioncheck)

"Deflection Length" divided by theMaximum allowable local deflection

DJ1 Start Jointof member

Joint No. denoting starting pointfor calculation of "DeflectionLength" (See Note 1)

DJ2 End Joint ofmember

Joint No. denoting end point for cal-culation of "Deflection Length" (SeeNote 1)

Table 7B.1 - French Steel Design Parameters

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ParameterName

DefaultValue

Description

DMAX 100.0 cm. Maximum allowable depth (used inmember selection).

DMIN 0.0 cm. Minimum allowable depth (used inmember selection).

FYLD 250.0 MPa Yield strength of steel.

KY 1.0 K value for axial compressionbuckling about local Y-axis.Usually, this is the minor axis.

KZ 1.0 K value for axial compressionbuckling about local Z-axis.Usually, this is the major axis.

LY MemberLength

Length to calculate slendernessratio about Y-axis for axialcompression.

LZ MemberLength

Length to calculate slendernessratio about Z-axis for axialcompression.

NSF 1.0 Net section factor for tensionmembers.

RATIO 1.0 Permissible ratio of actual loadeffect and design strength.

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ParameterName

DefaultValue

Description

SAME* 0.0 Controls the sections to try duringa SELECT process.

0.0  =  Try everysection of the same typeas original

1.0  =  Try only thosesections with a similarname as original, e.g.,if the original is an HEA100, then only HEAsections will beselected, even if thereare HEM’s in the sametable.

TRACK 0.0 0.0 =  Suppress printing of alldesign strengths.

1.0 =  Print all design strengths.

UNF 1.0 Same as above provided as afraction of member length.

UNL MemberLength

Unsupported length ofcompression flange for calculatingmoment resistance.

*For angles, if the original section is an equal angle, then the selected section willbe an equal angle and vice versa for unequal angles.

7B.6 Code  Checking  and  Member  Selection

Both code checking and member selection options are available in the STAAD.Proimplementation of CM 66 (Revn. 80).

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

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Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

7B.7 Tabulated Results of Steel Design

Results of code checking and member selection are presented in the output file in atabular format.

Note: COND CRITIQUE refers to the section of the CM 66 (Revn. 80)specification which governed the design.

If the TRACK parameter is set to 1.0, calculated member capacities will be printed.The following is a detailed description of printed items:

PC = Member Compression Capacity

TR = Member Tension Capacity

MUZ = Member Moment Capacity (about z-axis)

MUY = Member Moment Capacity (about y-axis)

VPZ = Member Shear Capacity (z-axis)

VPY = Member Shear Capacity (y-axis)

STAAD contains a broad set of facilities for designing structural members asindividual components of an analyzed structure. The member design facilitiesprovide the user with the ability to carry out a number of different designoperations. These facilities may be used selectively in accordance with therequirements of the design problem. The operations to perform a design are:

l Specify the members and the load cases to be considered in the design.

l Specify whether to perform code checking or member selection.

l Specify design parameter values, if different from the default values.

These operations may be repeated by the user any number of times dependingupon the design requirements.

Currently STAAD supports steel design of wide flange, S, M, HP shapes, angle,double angle, channel, double channel, beams with cover plate, composite beamsand code checking of prismatic properties.

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Sample Input data for Steel Design:

UNIT METER

PARAMETER

CODE FRENCH

NSF 0.85 ALL

UNL 10.0 MEMBER 7

KY 1.2 MEMBER 3 4

RATIO 0.9 ALL

TRACK 1.0 ALL

CHECK CODE ALL

7B.8 Built-in  French  Steel  Section  Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, the properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredfor these members.

An example of the member property specification in an input file is provided at theend of this section.

A complete listing of the sections available in the built-in steel section library maybe obtained by using the tools of the graphical user interface.

Following are the descriptions of different types of sections.

IPE Shapes

These shapes are designated in the following way.

10 15 TA ST IPE140

20 TO 30 TA ST IPEA120

33 36 TO 46 BY 2 TA ST IPER180

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HE shapes

HE shapes are specified as follows.

3 5 TA ST HEA120A

7 10 TA ST HEM140

13 14 TA ST HEB100

IPN Shapes

The designation for the IPN shapes is similar to that for the IPE shapes.

25 TO 35 TA ST IPN200

23 56 TA ST IPN380

T Shapes

Tee sections are not input by their actual designations, but instead by referring tothe I beam shapes from which they are cut. For example,

1 5 TA T IPE140

2 8 TA T HEM120

U Channels

Shown below is the syntax for assigning 4 different names of channel sections.

1 TO 5 TA ST UAP100

6 TO 10 TA ST UPN220

11 TO 15 TA ST UPN240A

16 TO 20 TA ST UAP250A

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Double U Channels

Back to back double channels, with or without a spacing between them, areavailable. The letter D in front of the section name will specify a double channel.

11 TA D UAP150

17 TA D UAP250A SP 0.5

In the above set of commands, member 11 is a back-to-back double channelUAP150 with no spacing in between. Member 17 is a double channel UAP250A witha spacing of 0.5 length units between the channels.

Angles

Two types of specification may be used to describe an angle. The standard anglesection is specified as follows:

16 20 TA ST L30X30X2.7

The above section signifies an angle with legs of length 30mm and a leg thicknessof 2.7mm. This specification may be used when the local Z axis corresponds to thez-z axis specified in Chapter 2. If the local Y axis corresponds to the z-z axis, typespecification "RA" (reverse angle) should be used instead of ST.

17 21 TA RA L25X25X4

22 24 TA RA L100X100X6.5

Note that if the leg thickness is a round number such as 4.0, only the number 4appears in the section name, the decimal part is not part of the section name.

Double Angles

Short leg back-to-back or long leg back-to-back double angles can be specified bymeans of input of the words SD or LD, respectively, in front of the angle size. Incase of an equal angle, either SD or LD will serve the purpose.

33 35 TA SD L30X20X4 SP 0.6

37 39 TA LD L80X40X6

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43 TO 47 TA LD L80X80X6.5 SP 0.75

Tubes (Rectangular or Square Hollow Sections)

Section names of tubes, just like angles, consist of the depth, width and wallthickness as shown below.

64 78 TA ST TUB50252.7

66 73 TA ST TUB2001008.0

Members 64 and 78 are tubes with a depth of 50mm, width of 25mm and a wallthickness of 2.7mm. Members 66 and 73 are tubes with a depth of 200mm, widthof 100mm and a wall thickness of 8.0mm. Unlike angles, the ".0" in the thickness ispart of the section name.

Tubes can also be input by their dimensions instead of by their table designations.For example,

6 TA ST TUBEDT 8.0WT 6.0 TH 0.5

is a tube that has a depth of 8 length units, width of 6 length units, and a wallthickness of 0.5 length units. Only code checking, no member selection, will beperformed for TUBE sections specified in this way.

Pipes (Circular Hollow Sections)

To designate circular hollow sections, use PIP followed by numerical value of thediameter and thickness of the section in mm omitting the decimal portion of thevalue provided for the diameter. The following example illustrates the designation.

8 TO 28 TA ST PIP422.6

3 64 78 TA ST PIP21912.5

Members 8 to 28 are pipes 42.4mm in dia, having a wall thickness of 2.6mm.Members 3, 64 and 78 are pipes 219.1mm in dia, having a wall thickness of12.5mm.

Circular hollow sections may also be provided by specifying the outside and insidediameters of the section. For example,

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1 TO 9 TA ST PIPE OD 25.0 ID 20.0

specifies a pipe with outside dia. of 25 length units and inside dia. of 20 lengthunits. Only code checking, no member selection will be performed if this type ofspecification is used.

SAMPLE FILE CONTAINING FRENCH SHAPES

STAAD SPACE

UNIT METER KN

JOINT COORD

1 0 0 0 15 140 0 0

MEMB INCI

1 1 2 14

UNIT CM

MEMBER PROPERTIES FRENCH

* IPE SHAPES

1 TA ST IPEA120

* IPN SHAPES

2 TA ST IPN380

*HE SHAPES

3 TA ST HEA200

* T SHAPES

4 TA T HEM120

* U CHANNELS

5 TA ST UAP100

* DOUBLE U CHANNELS

6 TA D UAP150 SP 0.5

* ANGLES

7 TA ST L30X30X2.7

* REVERSE ANGLES

8 TA RA L25X25X4

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* DOUBLE ANGLES - SHORT LEGS BACK

* TOBACK

9 TA SD L30X20X4 SP 0.25

* DOUBLE ANGLES - LONG LEGS BACK

* TOBACK

10 TA LD L80X40X6 SP 0.75

* TUBES (RECTANGULAROR SQUARE

* HOLLOWSECTIONS)

11 TA ST TUB50252.7

* TUBES (RECTANGULAROR SQUARE

* HOLLOWSECTIONS)

12 TA ST TUBEDT 8.0WT 6.0 TH 0.5

* PIPES (CIRCULAR HOLLOWSECTIONS)

13 TA ST PIP422.6

* PIPES (CIRCULAR HOLLOWSECTIONS)

14 TA ST PIPE OD 25.0 ID 20.0

PRINT MEMB PROP

FINI

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Section 8

German Codes

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German Codes - Concrete Design Per DIN 10458A.1 Design  Operations

STAAD has the capabilities of performing concrete design based on the DIN 1045 -November 1989. Slab design is also available but this follows the requirements ofBaumann, Munich, which is the basis for Eurocode 2. Design for a member involvescalculation of the amount of reinforcement required for the member. Calculationsare based on the user specified properties and the member forces obtained fromthe analysis. In addition, the  details regarding placement of the reinforcement onthe cross section are also reported in the output.

8A.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be designed.

l For Beams — Prismatic (Rectangular & Square)

l For Columns — Prismatic (Rectangular, Square, and Circular)

8A.3 Member Dimensions

Concrete members which will be designed by the programmust have certainsection properties input under the MEMBER PROPERTY command. The followingexample shows the required input:

UNIT MM

MEMBER PROPERTY

1 3 TO 7 9 PRISM YD 450. ZD 250.

11 13 PR YD 350.

In the above input, the first set of members are rectangular (450 mm depth and250 mmwidth) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with 350 mm diameter. It is absolutelyimperative that the user not provide the cross section area (AX) as an input.

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8A.4 Slenderness Effects and Analysis Con-siderations

Slenderness effects are extremely important in designing compression members.There are two options by which the slenderness effect can be accommodated.

The first method is equivalent to the procedure presented in DIN 104517.4.3/17.4.4 which is used as the basis for commonly used design chartsconsidering e/d and sk/d for conditions where the slenderness moment exceeds70. This method has been adopted in the column design in STAAD per the DINcode.

The second option is to compute the secondary moments through an analysis.Secondary moments are caused by the interaction of the axial loads and therelative end displacements of a member. The axial loads and joint displacementsare first determined from an elastic stiffness analysis and the secondary momentsare then evaluated. To perform this type of analysis, use the command PDELTAANALYSIS instead of PERFORM ANALYSIS in the input file. The user must notethat to take advantage of this analysis, all the combinations of loading must beprovided as primary load cases and not as load combinations. This is due to thefact that load combinations are just algebraic combinations of forces andmoments, whereas a primary load case is revised during the P-delta analysis basedon the deflections. Also, note that the proper factored loads (like 1.5 for dead loadetc.) should be provided by the user. STAAD does not factor the loadsautomatically. The column is designed for the total moment which is the sum ofthe primary and secondary forces. The secondary moments can be compared tothose calculated using the charts of DIN 1045.

8A.5 Beam  Design

Beams are designed for flexure, shear and torsion. For all these forces, all activebeam loadings are prescanned to identify the critical load cases at differentsections of the beams. The total number of sections considered is 13 (e.g., 0., .1,.2, .25, .3, .4, .5, .6, .7, .75, .8, .9 and 1). All of these sections are scanned todetermine the design force envelopes.

Design for Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) andhogging (creating tensile stress at the top face) moments are calculated for all

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active load cases at each of the above mentioned sections. Each of these sections isdesigned to resist these critical sagging and hogging moments. Currently, design ofsingly reinforced sections only is permitted. If the section dimensions areinadequate as a singly reinforced section, such a message will be printed in theoutput. Flexural design of beams is performed in two passes. In the first pass,effective depths of the sections are determined with the assumption of single layerof assumed reinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database in singleor multiple layers. The entire flexural design is performed again in a second passtaking into account the changed effective depths of sections calculated on the  basisof reinforcement provided after the preliminary design. Final provisions of flexuralreinforcements are made then. Efforts have been made to meet the guideline forthe curtailment of reinforcements as per the DIN code. Although exact curtailmentlengths are not mentioned explicitly in the design output (finally which will be moreor less guided by the detailer taking into account of other practical considerations),the user has the choice of printing reinforcements provided by STAAD at 13 equallyspaced sections from which the final detailed drawing can be prepared.

Design for Shear and Torsion

Shear design in STAAD conforms to the specifications of section 17.5 of DIN 1045.Shear reinforcement is calculated to resist both shear forces and torsionalmoments. Shear and torsional design is performed at the start and end sections ofthe member at a distance "d" away from the node of the member where "d" is theeffective depth calculated from flexural design. The maximum shear forces fromamongst the active load cases and the associated torsional moments are used in thedesign. The capacity of the concrete in shear and torsion is determined at thelocation of design and the balance, if any, is carried by reinforcement. It is assumedthat no bent-up bars are available from the flexural reinforcement to carry and"balance" shear. Two-legged stirrups are provided to take care of the balance shearforces acting on these sections. Stirrups are assumed to be U-shaped for beamswith no torsion, and closed hoops for beams subject to torsion.

Example of Input Data for Beam Design

UNIT NEWTON MMS

START CONCRETEDESIGN

CODEGERMAN

FYMAIN 415 ALL

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FYSEC 415 ALL

FC 35 ALL

CLEAR 25 MEM2 TO6

MAXMAIN 40 MEMB 2 TO 6

TRACK 1.0 MEMB 2 TO 9

DESIGN BEAM 2 TO9

END CONCRETEDESIGN

8A.6 Column Design

Columns are designed for axial forces and biaxial moments at the ends. All activeload cases are tested to calculate reinforcement. The loading which yieldsmaximum reinforcement is called the critical load. The requirements of DIN 1045-figure 13, for calculating the equilibrium equations for rectangular and circularsections from first principles, is implemented in the design. The user has control ofthe effective length (sk) in each direction by using the ELZ and ELY parameters asdescribed on Table 8A.1. This means that the slenderness will be evaluated alongwith e/d to meet the requirements of DIN 1045 section 17.4.3 and 17.4.4.

Column design is done for square, rectangular and circular sections. Square andrectangular columns are designed with reinforcement distributed on all four sidesequally. That means the total number of bars will always be a multiple of four (4).This may cause slightly conservative results in some cases. The TRACK parametermay be used to obtain the design details in various levels of detail.

Example of Input Data for Column Design

UNIT NEWTON MMS

START CONCRETEDESIGN

CODEGERMAN

FYMAIN 415 ALL

FC 35 ALL

CLEAR 25 MEMB 2 TO 6

MAXMAIN 40 MEMB 2 TO 6

DESIGN COLUMN 2 TO6

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END CONCRETEDESIGN

8A.7 Slab Design

To design a slab, it must first be modeled using finite elements and analyzed. Thecommand specifications are in accordance with Section 5.52 of the TechnicalReference Manual. Slabs are designed to specifications as described by BAUMANNof MUNICH which is the basis for Eurocode 2.

Elements are designed for the moments Mx and My. These moments are obtainedfrom the element force output (see Chapter 2 of the Technical Reference Manual).The reinforcement required to resist the Mx moment is denoted as longitudinalreinforcement and the reinforcement required to resist the My moment is denotedas transverse reinforcement. The following parameters are those applicable to slabdesign:

l FYMAIN — Yield stress for all reinforcing steel

l FC — Concrete grade

l CLEAR — Distance from the outer surface of the element to the edge of thebar. This is considered the same on both top and bottom surfaces of the ele-ment.

l SRA —  Parameter which denotes the angle of direction of the required trans-verse reinforcement relative to the direction of the longitudinal reinforcementfor the calculation of BAUMANN design forces.

The other parameters shown in Table 8A.1 are not applicable to slab design.

BAUMANN equations

If the default value of zero is used, the design will be based on Mx and My forceswhich are obtained from the STAAD analysis. The SRA parameter (SetReinforcement Angle) can be manipulated to introduce resolved BAUMANN forcesinto the design replacing the pure Mx and My moments. These new designmoments allow the Mxy moment to be considered when designing the section,resolved as an axial force. Orthogonal or skew reinforcement may be considered. IfSRA is set to -500, an orthogonal layout will be assumed. If however a skew is tobe considered, an angle is given in degrees measured from the local element X axisanticlockwise (positive). The resulting Mx* and My* moments are calculated andshown in the design format.

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The design of the slab considers a fixed bar size of 10 mm in the longitudinaldirection and 8 mm in the transverse. The longitudinal bar is the layer closest tothe slab exterior face.

8A.8 Design Parameters

The program contains a number of parameters which are needed to perform thedesign. Default parameter values have been selected such that they are frequentlyused numbers for conventional design requirements. These values may bechanged to suit the particular design being performed. Table 8A.1 of this manualcontains a complete list of the available parameters and their default values. It isnecessary to declare length and force units as Millimeter and Newton beforeperforming the concrete design.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as DIN1045.

Design Code to follow.

See section 5.52.2 of the TechnicalReference Manual.

CLEAR 25 mm Clear cover for reinforcementmeasured from concrete surface toclosest bar perimeter.

DEPTH YD Depth of concrete member. Thedefault value is provided as YD inMEMBER PROPERTIES. 

Table 8A.1 - German Concrete Design Parameters

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ParameterName

DefaultValue

Description

EFACE 0.0 Face of support location at end ofbeam, measured from the endjoint.

Note: Both SFACE & EFACEmust be positive numbers.

ELY 1.0 Member length factor about local Ydirection for column design.

ELZ 1.0 Member length factor about local Zdirection for column design.

FC 25 N/mm2 Concrete Yield Stress / cubestrength

FYMAIN 420 N/mm2 Yield Stress for main reinforcement(For slabs, it is 500 N/mm2 forboth directions)

FYSEC 420 N/mm2 Yield Stress for secondaryreinforcement a. Applicable toshear and torsion reinforcement inbeams

MAXMAIN 50 mm Maximum required reinforcementbar size. Acceptable bars are perMINMAIN above.

MINMAIN 16 mm Minimummain reinforcement barsize Acceptable bar sizes: 6 8 1012 14 16 20 25 32 40 50

MINSEC 8 mm Minimum secondary reinforcementbar size. Applicable to shear andtorsion reinforcement in beams.

MMAG 1.0 Factor by which column designmoments are magnified for columndesign

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ParameterName

DefaultValue

Description

NSECTION 10 Number of equally-spaced sectionsto be considered in finding criticalmoment for beam design. Theupper limit is 20.

SFACE 0.0 Face of support location at start ofbeam, measured from the startjoint. (Only applicable for shear -use MEMBER OFFSET for bending)

SRA 0.0 0.0 = Orthogonal reinforcementlayout without consideringtorsional moment Mxy -slabs only

-500 = Orthogonal reinforcementlayout considering Mxy

A = Skew angle considered inBAUMANN equations. A is theangle in degrees.

TRACK 0.0 Level of detail in output

0. Critical Moment will not beprinted with beam designreport.

1. For beam gives min/maxsteel % and spacing. For col-umns gives a detailed tableof output with additionalmoments calculated.

2. For beams gives area of steelrequired at intermediate sec-tions. (see NSECTION)

WIDTH ZD Width of concrete member. Thisvalue default is as provided as ZDin MEMBER PROPERTIES.

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German Codes - Steel Design Per the DIN Code

8B.1 General

This section presents some general statements regarding the implementation of theDIN code of practice for structural steel design (DIN 18800 – Parts 1 & 2) inSTAAD. The design philosophy and procedural logistics are based on the principlesof elastic analysis and allowable stress design. Facilities are available for memberselection as well as code checking. Two major failure modes are recognized: failureby overstressing and failure by stability considerations. The following sectionsdescribe the salient features of the design approach.

Members are proportioned to resist the design loads without exceedance of theallowable stresses or capacities and the most economical section is selected on thebasis of the least weight criteria. The code checking part of the program also checksthe slenderness requirements and the stability criteria. It is recommended that youuse the following steps in performing the steel design:

1. Specify the geometry and loads and perform the analysis.

2. Specify the design parameter values if different from the default values.

3. Specify whether to perform code checking or member selection.

8B.2 AnalysisMethodology

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loading specificationsand in using appropriate load factors to create necessary loading situations.Depending upon the analysis requirements, regular stiffness analysis or P-Deltaanalysis may be specified. Dynamic analysis may also be performed and the resultscombined with static analysis results.

8B.3 Member Property Specifications

For specification of member properties of standard German steel sections, the steelsection library available in STAAD may be used. The next section describes thesyntax of commands used to assign properties from the built-in steel table. Member

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properties may also be specified using the User Table facility. For moreinformation on these facilities, refer to Section 1.7 the STAAD Technical ReferenceManual.

8B.4 Built-in German Steel Section Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, these properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredfor these members during the analysis. An example of member propertyspecification in an input file is provided at the end of this section.

A complete listing of the sections available in the built-in steel section library maybe obtained using the tools of the graphical user interface.

Refer to Section 1.7.2 of the Technical Reference Manual for additionalinformation.

Following are the descriptions of different types of sections.

IPE Shapes

These shapes are designated in the following way:

20 TO 30 TA ST IPEA120

33 36 TO 46 BY 2 TA ST IPER140

HE Shapes

The designation for HE shapes is similar to that for IPE shapes.

25 TO 35 TA ST HEB300

23 56 TA ST HEA160

I Shapes

I shapes are identified by the depth of the section. The following exampleillustrates the designation.

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14 15 TA ST I200 (INDICATES AN I-SECTIONWITH 200MMDEPTH)

T Shapes

Tee sections are not input by their actual designations, but instead by referring tothe I beam shapes from which they are cut. For example,

1 5 TA T HEA220

2 8 TA T IPE120

U Channels

The example below provides the command for identifying two channel sections.The former (U70X40) has a depth of 70mm and a flange width of 40mm. The latter(U260) has a depth of 260mm.

11 TA D U70X40      

27 TA D U260

Double Channels

Back-to-back double channels, with or without spacing between them, areavailable. The letter “D” in front of the section name will specify a double channel,e.g., D U180. The spacing between the double channels is provided following theexpression “SP”.

11 TA D U180      

27 TA D U280 SP 0.5 (INDICATES 2 CHANNELS BACK-TO-BACKSPACED AT 0.5 LENGTH UNITS)

Angles

Two types of specifications may be used to describe an angle. The standard anglesection is specified as follows:

16 20 TA ST L20X20X2.5

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The above section signifies an angle with legs of length 20mm and a leg thicknessof 2.5mm. The above specification may be used when the local z-axis correspondsto the Z-Z axis specified in Chapter 2. If the local y-axis corresponds to the Z-Zaxis, type specification "RA" (reverse angle) may be used.

17 21 TA RA L40X20X5

Double Angles

Short leg back-to-back or long leg back-to-back double angles can be specified byusing the word SD or LD, respectively, in front of the angle size. In case of anequal angle, either SD or LD will serve the purpose. Spacing between the angles isprovided by using the word SP and the spacing value following the section name.

14 TO 20 TA SD L40X20X4 SP 0.5

21 TO 27 TA LD L40X20X4 SP 0.5

Pipes (Circular Hollow Sections)

To designate circular hollow sections, use PIP followed by numerical value of thediameter and thickness of the section in mm omitting the decimal section of thevalue provided for diameter. The following example will illustrate the designation.

8 TO 28 TA ST PIP602.9     (60.3MMDIA, 2.9MMWALLTHICKNESS)

3 64 67 TA ST PIP40612.5   (406.4MMDIA, 12.5MMWALLTHICKNESS)

Circular hollow sections may also be provided by specifying the outside and insidediameters of the section. For example,

1 TO 9 TA ST PIPE OD 25.0 ID 20.0

specifies a pipe with outside dia. of 25 and inside dia. of 20 in current length units.Only code checking and no member selection will be performed if this type ofspecification is used.

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Tubes (Rectangular or Square Hollow Sections)

Tube names are input by their dimensions. For example,

15 TO 25 TA ST TUB100603.6

is the specification for a tube having sides of 100mm x 60mm and the wallthickness of 3.6mm.

Tubes, like pipes can also be input by their dimensions (Height, Width andThickness) instead of by their table designations.

6 TA ST TUBEDT 8.0WT 6.0 TH 0.5

is a tube that has a height of 8, a width of 6, and a wall thickness of 0.5 in currentlength units. Only code checking and no member selection will be performed forTUBE sections specified this way.

SAMPLE INPUT FILE CONTAINING GERMAN SHAPES

STAAD SPACE

UNIT METER KN

JOINT COORDINATES

1 0 0 0 15 140 0 0

MEMBER INCIDENCES

1 1 2 14

UNIT CM

MEMBER PROPERTIES GERMAN

* IPE SHAPES

1 TA ST IPEA120

* HE SHAPES

2 TA ST HEB300

* I SHAPES

3 TA ST I200

* T SHAPES

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4 TA T HEA220

* U CHANNELS

5 TA ST U70X40

* DOUBLE U CHANNELS

6 TA D U260

* ANGLES

7 TA ST L20X20X2.5

* REVERSE ANGLES

8 TA RA L40X20X5

* DOUBLE ANGLES - LONG LEGS BACK TOBACK

9 TA LD L40X20X4 SP 0.5

* DOUBLE ANGLES - SHORT LEGS BACK TOBACK

10 TA SD L40X20X4 SP 0.5

* PIPES

11 TA ST PIP602.9

* PIPES

12 TA ST PIPE OD 25.0 ID 20.0

* TUBES

13 TA ST TUB100603.6

* TUBES

14 TA ST TUBEDT 8.0WT 6.0WT 0.5

*

PRINT MEMBER PROPERTIES

FINISH

8B.5 Member Capacities

The allowable stresses used in the implementation are based on DIN 18800 (Part1) - Section 7. The procedures of DIN 18800 Part 2 are used for stability analysis.The basic measure of member capacities are the allowable stresses on the memberunder various conditions of applied loading such as allowable tensile stress,allowable compressive stress etc. These depend on several factors such as cross

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sectional properties, slenderness factors, unsupported width to thickness ratios andso on. Explained here is the procedure adopted in STAAD for calculating suchcapacities.

Checks for Axial Tension

In members with axial tension, the tensile load must not exceed the tensioncapacity of the member. The tension capacity of the member is calculated on thebasis of the member area. STAAD calculates the tension capacity of a given memberbased on a user supplied net section factor (NSF -a default value of 1.0 is presentbut may be altered by changing the input value, see Table 8B.1) and proceeds withmember selection or code checking.

Checks for Axial Compression

The compression capacity for members in compression is determined according tothe procedure of DIN 18800- Part 2. Compressive resistance is a function of theslenderness of the cross-section (Kl/r ratio) and the user may control theslenderness value by modifying parameters such as KY, LY, KZ and LZ.

Checks for Bending and Shear

The bending compressive and tensile capacities are dependent on such factors aslength of outstanding legs, thickness of flanges, unsupported length of thecompression flange (UNL, defaults to member length) etc. Shear capacities are afunction of web depth, web thickness etc. Users may use a value of 1.0 or 2.0 forthe TRACK parameter to obtain a listing of the bending and shear capacities.

8B.6 Combined Loading

For members experiencing combined loading (axial force, bending, and shear),applicable interaction formulas are checked at different locations of the member forall modeled loading situations. Members subjected to axial force and bending arechecked using the criteria of DIN 18800 (Part 1) - Section 6.1.6. In addition, formembers with axial loads and bending, the criteria of DIN 18800(Part 2) - Sections3.4 and 3.5 are used.

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8B.7 Design Parameters

You are allowed complete control over the design process through the use ofparameters described in the following table. These parameters communicatedesign decisions from the engineer to the program. The default parameter valueshave been selected such that they are frequently used numbers for conventionaldesign. Depending on the particular design requirements of the situation, some orall of these parameter values may have to be changed to exactly model thephysical structure.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as DIN18800.

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM 0.0 Number of sections to be checkedper member:

0. Design only for end sections.

1. Check at location of max-imum MZ along member.

2. Check ends plus location ofbeam 1.0 check.

3. Check at every 1/13th of themember length and reportthe maximum.

CB 0 Beam coefficient n, defined inTable 9: If Cb = 0, program willuse n = 2.5 for rolled sections and2.0 for welded sections.

Table 8B.1 - German Steel Design Parameters

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ParameterName

DefaultValue

Description

CMM 1.0 Moment factor, Zeta, defined inTable 10:

1. fixed ended member withconstant moment, Zeta = 1.0

2. pin ended member with UDL,Zeta = 1.12

3. pin ended member with cen-tral point load, Zeta = 1.35

4. fixed ended member, Zeta cal-culated from end moments.

DMAX 1.0 m Maximum allowable depth duringmember selection

DMIN 0.0 m Minimum required depth duringmember selection

KY 1.0 K value in local y-axis. Usually, thisis the minor axis.

KZ 1.0 K value in local z-axis. Usually, thisis the major axis.

LY MemberLength

Length in local y-axis to calculateslenderness ratio.

LZ MemberLength

Length in local z-axis to calculateslenderness ratio.

PY 240N/sq.mm

Strength of steel.

NSF 1.0 Net section factor for tensionmembers.

RATIO 1.0 Permissible ratio of actual toallowable stresses

SAME 0.0 Control of sections to try during aSELECT process:

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ParameterName

DefaultValue

Description

0. Try every section of the sametype as the original.

1. Try only those with a similarname.

SBLT 0 Specify section as either rolled orbuilt-up:

0. Rolled

1. Built-up

SGR 0.0 Grade of steel:

0. St 37-2

1. St 52-3

2. St E 355

TRACK 0.0 Level of detail in output file:

0. Output summary of results

1. Output summary of resultsplus member capacities

2. Output detailed results

UNF 1.0 Same as above provided as a factorof actual member length.

UNL MemberLength

Unrestrained member length inlateral torsional buckling checks.

8B.8 Code Checking

The purpose of code checking is to check whether the provided section propertiesof the members are adequate to carry the forces transmitted to it by the loads onthe structure. The adequacy is checked per the DIN requirements.

Code checking is done using forces and moments at specified sections of themembers. If the BEAM parameter for a member is set to 1, moments are calculatedat every twelfth point along the beam, and the maximummoment about the major

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axis is used. When no sections are specified and the BEAM parameter is set to zero(default), design will be based on member start and end forces. The code checkingoutput labels the members as PASSed or FAILed. In addition, the critical condition,governing load case, location (distance from start joint) and magnitudes of thegoverning forces and moments are also printed.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

8B.9 Member Selection

The member selection process basically involves determination of the least weightmember that PASSes the code checking procedure based on the forces andmoments of the most recent analysis. The section selected will be of the same typeas that specified initially. For example, a member specified initially as a channel willhave a channel selected for it. Selection of members whose properties are originallyprovided from a user table will be limited to sections in the user table. Memberselection cannot be performed on TUBES, PIPES, or members listed as PRISMATIC.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

Sample Input data for Steel Design

UNIT METER

PARAMETER

CODEGERMAN

NSF 0.85 ALL

UNL 10.0 MEMBER 7

KY 1.2 MEMBER 3 4

RATIO 0.9 ALL

TRACK 1.0 ALL

CHECK CODE ALL

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Section 9

Indian Codes

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Indian Codes - Concrete Design per IS4569A.1 Design Operations

STAAD has the capabilities of performing concrete design based on the limit statemethod of IS: 456 (2000).

9A.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be designed.

l For Beams — Prismatic (Rectangular & Square),  T-Beams, and L-shapes

l For Columns — Prismatic (Rectangular, Square, and Circular)

9A.3 Member Dimensions

Concrete members which will be designed by the programmust have certainsection properties input under the MEMBER PROPERTY command. The followingexample shows the required input:

UNIT MM

MEMBER PROPERTY

1 3 TO 7 9 PRISM YD 450. ZD 250.

11 13 PR YD 350.

14 TO 16 PRIS YD 400. ZD 750. YB 300. ZB 200.

will be done accordingly. In the above input, the first set of members arerectangular (450 mm depth and 250mmwidth) and the second set of members,with only depth and no width provided, will be assumed to be circular with 350 mmdiameter. The third set numbers in the above example represents a T-shape with750 mm flange width, 200 width, 400 mm overall depth and 100 mm flange depth(See section 6.20.2). The program will determine whether the section isrectangular, flanged or circular and the beam or column design.

9A.4 Design Parameters

The program contains a number of parameters which are needed to perform designas per IS:456(2000).  Default parameter values have been selected such that theyare frequently used numbers for conventional design requirements. These values

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may be changed to suit the particular design being performed. Table 9A.1 of thismanual contains a complete list of the available parameters and their  defaultvalues. It is necessary to declare length and force units as Millimeter and Newtonbefore performing the concrete design.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as INDIAN.

Design Code to follow.

See section 5.52.2 of the TechnicalReference Manual.

BRACING 0.0 Beam Design:

A value of 1.0 meansthe effect of axial forcewill be taken intoaccount for beamdesign.

Column Design:

correspond to the terms"Braced" and"Unbraced" described inNotes 1, 2, and 3 ofClause 39.7.1 ofIS456:2000.

1. The column is unbracedabout major axis.

2. The column is unbracedabout minor axis.

3. The column is unbracedabout both axis.

Table 9A.1 - Indian Concrete Design IS456 Parameters

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ParameterName

DefaultValue

Description

CLEAR 25 mm

40 mm

For beammembers.

For column members

DEPTH YD Total depth to be used for design.This value defaults to YD asprovided under MEMBERPROPERTIES.

EFACE 0.0 Face of support location at end ofbeam. The parameter can also beused to check against shear at anypoint from the end of the member.

Note: Both SFACE and EFACEare input as positive numbers.

ELZ 1.0 Ratio of effective length to actuallength of column about major axis.See Note b below.

ELY 1.0 Ratio of effective length to actuallength of column about minor axis.See Note b below.

ENSH 0.0 Perform shear check againstenhanced shear strength as per Cl.40.5 of IS456:2000.

l ENSH = 1.0 means ordinaryshear check to be performed( no enhancement of shearstrength at sections close tosupport)

l For ENSH = a positivevalue(say x ), shear strengthwill be enhanced up to a dis-tance x from the start of themember. This is used only

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ParameterName

DefaultValue

Description

when a span of a beam is sub-divided into two or moreparts. (Refer note )

l For ENSH = a negativevalue(say –y), shear strengthwill be enhanced up to a dis-tance y from the end of themember. This is used onlywhen a span of a beam is sub-divided into two or moreparts.(Refer note)

If default value (0.0) is used theprogram will calculate Length toOverall Depth ratio. If this ratio isgreater than 2.5, shear strengthwill be enhanced at sections (<2d)close to support otherwise ordinaryshear check will be performed.

FC 30 N/mm2 Concrete Yield Stress.

FYMAIN 415 N/mm2 Yield Stress for main reinforcingsteel.

FYSEC 415 N/mm2 Yield Stress for secondaryreinforcing steel.

MINMAIN 10 mm Minimummain reinforcement barsize.

MAXMAIN 60 mm Maximummain reinforcement barsize.

MINSEC 8 mm Minimum secondary reinforcementbar size.

MAXSEC 12 mm Maximum secondary reinforcementbar size.

RATIO 4.0 Maximum percentage of

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ParameterName

DefaultValue

Description

longitudinal reinforcement incolumns.

REINF 0.0 Tied column. A value of 1.0 willmean spiral reinforcement.

RENSH 0.0 Distance of the start or end point ofthe member from its nearestsupport. This parameter is usedonly when a span of a beam issubdivided into two or more parts.(Refer note)

RFACE 4.0 2. Two faced distribution aboutmajor axis.

3. Two faced distribution aboutminor axis.

4. Longitudinal reinforcement incolumn is arranged equallyalong 4 faces.

SFACE 0.0 Face of support location at start ofbeam. It is used to check againstshear at the face of the support inbeam design. The parameter canalso be used to check against shearat any point from the start of themember.

SPSMAIN 25 mm Minimum clear distance betweenmain reinforcing bars in beam andcolumn. For column center tocenter distance between main barscannot exceed 300 mm.

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ParameterName

DefaultValue

Description

TORSION 0.0 0. torsion to be considered inbeam design.

1. torsion to be neglected inbeam design.

TRACK 0.0 Beam Design:

0. output consists of rein-forcement details at START,MIDDLE, and END.

1. critical moments are printedin addition to TRACK 0.0 out-put.

2. required steel for inter-mediate sections defined byNSECTION are printed inaddition to TRACK 1.0 out-put.

Column Design:

0. reinforcement details areprinted.

1. column interaction analysisresults are printed in additionto TRACK 0.0 output.

2. a schematic interaction dia-gram and intermediate inter-action values are printed inaddition to TRACK 1.0 out-put.

9. the details of section capacitycalculations are printed.

ULY 1.0 Ratio of unsupported length toactual length of column aboutminor axis. See Note c below.

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ParameterName

DefaultValue

Description

ULZ 1.0 Ratio of unsupported length toactual length of column aboutmajor axis. See Note c below.

WIDTH ZD Width to be used for design. Thisvalue defaults to ZD as providedunder MEMBER PROPERTIES.

Notes

a. You may specify reinforcing bar combinations through theBAR COMBINATION command. Refer to Section 9A.8 for details.

b. ELY and ELZ parameters are used to calculate effective length of column tofind whether it is a short or long column. Please refer CL 25.1.2 ofIS456:2000.

In CL 25.1.2 of IS456:2000, you will find two term, lexand l

ey, which STAAD

calculates as:

l lex= ELZ multiplied by the member length (distance between the two

nodes of the member)

l ley= ELY multiplied by the member length (distance between the two

nodes of the member)

For the term "D" in CL 25.1.2 of IS456:2000, STAAD uses the YD dimensionof the column.

For the term "b" in CL 25.1.2 of IS456:2000, STAAD uses the ZD dimensionof the column.

c. ULY and ULZ parameters are used to calculate unsupported length of columnto find minimum eccentricity. Please refer CL 25.4 of IS456:2000.

In CL 25.4 of IS456:2000, you will find an expression "unsupported length ofcolumn". This term is calculated as

l ULZ multiplied by the member length for the Z axis

l ULY multiplied by the member length for the Y axis

d. The value of the ENSH parameter (other than 0.0 and 1.0) is used only when

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the span of a beam is subdivided into two or more parts. When this conditionoccurs, the RENSH parameter is also to be used.

The span of the beam is subdivided four parts, each of length L meter. Theshear strength will be enhanced up to X meter from both supports. The inputshould be the following:

Steps:

1. ENSH L MEMB 1 => Shear strength will be enhanced throughoutthe length of the member 1, positive sign indicates length measuredfrom start of the member

2. ENSH (X-L) MEMB 2 => Shear strength will be enhanced up to alength (X-L) of the member 2, length measured from the start of themember

3. ENSH –L MEMB 4 => Shear strength will be enhanced throughoutthe length of the member 4, negative sign indicates length measuredfrom end of the member

4. ENSH –(X-L) MEMB 3 => Shear strength will be enhanced up to alength (X-L) of the member 3, length measured from the end of themember

5. RENSH L MEMB 2 3  => Nearest support lies at a distance L fromboth the members 2 and 3.

6. DESIGN BEAM 1 TO 4=> This will enhance the shear strength up tolength X from both ends of the beam consisting of members 1 to 4 andgives spacing accordingly.

At section = y1 from start of member 1 av = y1

At section = y2 from the start of member 2 av = y2+L

At section = y3 from the end of member 3 av = y3+L

At section = y4 from end of member 4 av = y4

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where tc, enhanced = 2dtc/av

At section 0.0, av becomes zero. Thus enhanced shear strength will becomeinfinity. However for any section shear stress cannot exceed tc, max. Henceenhanced shear strength is limited to a maximum value of tc, max.

9A.5 Slenderness Effects and Analysis Con-sideration

Slenderness effects are extremely important in designing compression members.The IS:456 code specifies two options by which the slenderness effect can beaccommodated (Clause 39.7). One option is to perform an exact analysis which willtake into account the influence of axial loads and variable moment of inertia onmember stiffness and fixed end moments, the effect of deflections on moment andforces and the effect of the duration of loads. Another option is to approximatelymagnify design moments.

STAAD has been written to allow the use of the first option. To perform this type ofanalysis, use the command PDELTA ANALYSIS instead of PERFORM ANALYSIS.The P-Delta analysis will accommodate all requirements of the second- orderanalysis described by IS:456, except for the effects of the duration of the loads. Itis felt that this effect may be safely ignored because experts believe that the effectsof the duration of loads are negligible in a normal structural configuration.

Although ignoring load duration effects is somewhat of an approximation, it mustbe realized  that the approximate evaluation of slenderness effects is also anapproximate method. In this method, additional moments are calculated based onempirical formula and assumptions on sidesway (Clause 39.7.1 and 39.7.1.1,IS:456 - 2000). The rules of Clause 39.7.1 have been implemented in STAAD.Pro.They will be checked if the ELY and ELZ parameters are specified.

Considering all these information, a P-Delta analysis, as performed by STAAD maybe used for the design of concrete members.

Note: To take advantage of this analysis, all the combinations of loading mustbe provided as primary load cases and not as load combinations. This is due tothe fact that load combinations are just algebraic combinations of forces andmoments (i.e., analysis results), whereas a primary load case is revised during

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the P-delta analysis based on the deflections. Loads can be combined prior toanalysis using the REPEAT LOAD command.

Note: You must specify the appropriate load factors (e.g., 1.5 for dead load,etc.) as STAAD does not factor the loads automatically.

9A.6 Beam Design

Beams are designed for flexure, shear and torsion. If required the effect the axialforce may be taken into consideration.  For all these forces, all active beamloadings are prescanned to identify the critical load cases at different sections ofthe beams. The total number of sections considered is 13 (e.g., 0., .1, .2, .25, .3,.4, .5, .6, .7, .75, .8, .9, and 1). All of these sections  are scanned to determine thedesign force envelopes.

Design  for  Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) andhogging (creating tensile stress at the top face) moments are calculated for allactive load cases at each of the above mentioned sections. Each of these sections isdesigned to resist both of these critical sagging and hogging moments. Whereever the rectangular section is inadequate as singly reinforced section, doublyreinforced section is tried. However, presently the flanged section is designed onlyas singly reinforced section under sagging moment. It may also be noted allflanged sections are automatically designed as rectangular section under hoggingmoment as the flange of the beam is ineffective under hogging moment. Flexuraldesign of beams is performed in two passes. In the first pass, effective depths ofthe sections are determined with the assumption of single layer of assumedreinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database insingle or multiple layers. The entire flexure design is performed again in a secondpass taking into account of the changed effective depths of sections calculated onthe basis of reinforcement provide after the preliminary design. Final provisions offlexural reinforcements are made then. Efforts have been made to meet theguideline for the curtailment of reinforcements as per IS:456-2000 (Clause26.2.3). Although  exact curtailment lengths are not mentioned explicitly in thedesign output (finally which will be more or less guided by the detailer taking intoaccount of other practical consideration), user has the choice of printing

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reinforcements provided by STAAD at 11 equally spaced sections from which thefinal detail drawing can be prepared.

Design  for  Shear

Shear reinforcement is calculated to resist both shear forces and torsionalmoments. Shear design are performed at 11 equally spaced sections (0.0 to 1.0)for the maximum shear forces amongst the active load cases and the associatedtorsional moments. Shear capacity calculation at different sections without theshear reinforcement is based on the actual tensile reinforcement provided bySTAAD program. Two-legged stirrups are provided to take care of the balanceshear forces acting on these sections.

As per Clause 40.5 of IS:456-2000 shear strength of sections (< 2d where d is theeffective depth) close to support has been enhanced, subjected to a maximumvalue of τ

cmax.

Beam Design Output

The default design output of the beam contains flexural and shear  reinforcementprovided at 5 equally spaced (0, .25, .5, .75 and 1.) sections along the length ofthe beam. User has option to get a more detail output. All beam design outputs aregiven in IS units. An example of rectangular beam design output with TRACK 2.0output is presented below:

B E A M N O. 1 D E S I G N R E S U L T S

M20 Fe415 (Main) Fe250 (Sec.)

LENGTH: 6400.0 mm SIZE: 300.0 mm X 400.0 mm COVER:25.0 mm

DESIGN LOAD SUMMARY (KN MET)--------------------------------------------------------------------

--------SECTION |FLEXURE (Maxm. Sagging/Hogging moments)| SHEAR(in mm) | P MZ MX Load Case | VY MX

Load Case--------------------------------------------------------------------

--------0.0 | 0.00 0.00 0.00 1 | 60.61 0.00

1| 0.00 0.00 0.00 1 |

533.3 | 0.00 29.63 0.00 1 | 50.51 0.001

| 0.00 0.00 0.00 1 |1066.7 | 0.00 53.88 0.00 1 | 40.41 0.001

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| 0.00 0.00 0.00 1 |1600.0 | 0.00 72.73 0.00 1 | 30.31 0.001

| 0.00 0.00 0.00 1 |2133.3 | 0.00 86.20 0.00 1 | 20.20 0.001

| 0.00 0.00 0.00 1 |2666.7 | 0.00 94.28 0.00 1 | 10.10 0.001

| 0.00 0.00 0.00 1 |3200.0 | 0.00 96.98 0.00 1 | 0.00 0.001

| 0.00 0.00 0.00 1 |3733.3 | 0.00 94.28 0.00 1 | -10.10 0.001

| 0.00 0.00 0.00 1 |4266.7 | 0.00 86.20 0.00 1 | -20.20 0.001

| 0.00 0.00 0.00 1 |4800.0 | 0.00 72.73 0.00 1 | -30.31 0.001

| 0.00 0.00 0.00 1 |5333.3 | 0.00 53.88 0.00 1 | -40.41 0.001

| 0.00 0.00 0.00 1 |5866.7 | 0.00 29.63 0.00 1 | -50.51 0.001

| 0.00 0.00 0.00 1 |6400.0 | 0.00 0.00 0.00 1 | -60.61 0.001

| 0.00 0.00 0.00 1 |-------------------------------------------------------------------

---------

SUMMARY OF REINF. AREA (Sq.mm)

----------------------------------------------------------------------------

SECTION | TOP | BOTTOM |STIRRUPS

(in mm) | Reqd./Provided reinf. | Reqd./Provided reinf. | (2legged)

----------------------------------------------------------------------------

0.0 | 0.00/ 402.12( 2-16í )| 0.00/ 981.75( 2-25í )| 8í@ 180 mm

533.3 | 0.00/ 402.12( 2-16í )| 237.32/1472.62( 3-25í )| 8í@ 180 mm

1066.7 | 0.00/ 402.12( 2-16í )| 450.84/1472.62( 3-25í )| 8í@ 180 mm

1600.0 | 0.00/ 402.12( 2-16í )| 632.82/1472.62( 3-25í )| 8í@ 180 mm

2133.3 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )| 8í@ 180 mm

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2666.7 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )| 8í @180 mm

3200.0 | 0.00/ 402.12( 2-16í )| 894.99/1472.62( 3-25í )| 8í @180 mm

3733.3 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )| 8í @180 mm

4266.7 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )| 8í @180 mm

4800.0 | 0.00/ 402.12( 2-16í )| 632.82/1472.62( 3-25í )| 8í @180 mm

5333.3 | 0.00/ 402.12( 2-16í )| 450.84/1472.62( 3-25í )| 8í @180 mm

5866.7 | 0.00/ 402.12( 2-16í )| 237.32/1472.62( 3-25í )| 8í @180 mm

6400.0 | 0.00/ 402.12( 2-16í )| 0.00/ 981.75( 2-25í )| 8í @180 mm

----------------------------------------------------------------------------

9A.7 Column Design

Columns are designed for axial forces and biaxial moments at the ends. All activeload cases are tested to calculate reinforcement. The loading which yield maximumreinforcement is called the critical load. Column design is done for square,rectangular and circular sections. By default, square and rectangular columns anddesigned with reinforcement distributed on each side equally for the sections underbiaxial moments and with reinforcement distributed equally  in two faces forsections under uniaxial moment. User may change the default arrangement of thereinforcement with the help of the parameter RFACE (see Table 8A.1). Dependingupon the member lengths, section dimensions and effective length coefficientsspecified by the user STAAD automatically determine the criterion (short or long) ofthe column design. All major criteria for selecting longitudinal and transversereinforcement as stipulated by IS:456 have been taken care of in the column designof STAAD. Default clear spacing between main reinforcing bars is taken to be 25mmwhile arrangement of longitudinal bars.

Column  Design  Output

Default column design output (TRACK 0.0) contains the reinforcement provided bySTAAD and the capacity of the section. With the option TRACK 1.0, the outputcontains intermediate results such as the design forces, effective length coefficients,additional moments etc. All design output is given in SI units. An example of aTRACK 2.0 output follows:

C O L U M N N O. 1 D E S I G N R E S U L T S

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M20 Fe415 (Main) Fe250(Sec.)

LENGTH: 3000.0 mm CROSS SECTION: 400.0 mm X 600.0 mm COVER:40.0 mm

** GUIDING LOAD CASE: 1 END JOINT: 1 SHORT COLUMN

DESIGN FORCES (KNS-MET)-----------------------DESIGN AXIAL FORCE (Pu) : 2000.00

About Z About YINITIAL MOMENTS : 160.00 120.00MOMENTS DUE TO MINIMUM ECC. : 52.00 40.00

SLENDERNESS RATIOS : - -MOMENTS DUE TO SLENDERNESS EFFECT : - -MOMENT REDUCTION FACTORS : - -ADDITION MOMENTS (Maz and May) : - -

TOTAL DESIGN MOMENTS : 160.00 120.00

REQD. STEEL AREA : 3587.44 Sq.mm.REQD. CONCRETE AREA: 236412.56 Sq.mm.MAIN REINFORCEMENT : Provide 32 - 12 dia. (1.51%, 3619.11

Sq.mm.)(Equally distributed)

TIE REINFORCEMENT : Provide 8 mm dia. rectangular ties @ 190 mmc/c

SECTION CAPACITY BASED ON REINFORCEMENT REQUIRED (KNS-MET)----------------------------------------------------------Puz : 3244.31 Muz1 : 269.59 Muy1 : 168.42

INTERACTION RATIO: 0.98 (as per Cl. 39.6, IS456:2000)

SECTION CAPACITY BASED ON REINFORCEMENT PROVIDED (KNS-MET)----------------------------------------------------------WORST LOAD CASE: 1END JOINT: 1 Puz : 3253.88 Muz : 271.48 Muy :

170.09 IR: 0.96

============================================================================

9A.8 Bar Combination

Initially the program selects only one bar to calculate the number of bars requiredand area of steel provided at each section along the length of the beam. You mayuse the BAR COMBINATION command to specify two bar diameters to calculate acombination of each bar to be provided at each section. The syntax for barcombination is given below.

START BAR COMBINATION

MD1 <bar diameter> MEMB <member list>

MD2 <bar diameter> MEMB <member list>

END BAR COMBINATION

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Note: The bar sizes should be specified in the order of increasing size (i.e., MD2bar diameter should be greater than MD1 bar diameter).

The beam length is divided into three parts, two at its ends and one at span. Ldgives the development length to be provided at the two ends of each section.

The typical output for bar combination is shown below:

OUTPUT FOR BAR COMBINATION

----------------------------------------------------------------------------

| M A I N R E I N F O R C E M E N T|

----------------------------------------------------------------------------

SECTION | 0.0- 1600.0 | 1600.0- 4800.0 | 4800.0-6400.0 |

| mm | mm | mm|

----------------------------------------------------------------------------

TOP | 2-16í | 2-16í | 2-16í|

| in 1 layer(s) | in 1 layer(s) | in 1layer(s) |

Ast Reqd| 0.00 | 0.00 | 0.00|Prov| 402.29 | 402.29 | 402.29|

Ld (mm) | 752.2 | 1175.3 | 752.2|

----------------------------------------------------------------------------

BOTTOM | 4-16í | 2-16í + 2-25í | 4-16í|

| in 1 layer(s) | in 1 layer(s) | in 1layer(s) |

Ast Reqd| 632.82 | 894.99 | 632.82|Prov| 804.57 | 1384.43 | 804.57|

Ld (mm) | 752.2 | 1175.3 | 752.2|

----------------------------------------------------------------------------

============================================================================

9A.9 Wall Design in accordance with IS 456-2000

The design of walls in accordance with IS 456-2000 is available in STAAD.Pro.

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The design is performed for in-plane shear, in-plane & out-of-plane bending, andout-of-plane shear. The wall has to be modeled using STAAD’s Surface elements(Refer to Section 5.13.3 of the Technical Reference Manual). The use of theSurface element enables the designer to treat the entire wall as one entity. Itgreatly simplifies the modeling of the wall and adds clarity to the analysis anddesign output. The results are presented in the context of the entire wall ratherthan individual finite elements thereby allowing users to quickly locate requiredinformation.

The program reports shear wall design results for each load case/combination forthe specified number of sections given in the SURFACE DIVISION command(default value is 10) command. The shear wall is designed at these horizontalsections. The output includes the required horizontal and vertical distributedreinforcing, the concentrated (in-plane bending) edge reinforcing and the linkrequired for out-of-plane shear.

Refer to Section 5.54 of the Technical Reference Manual for additional details onshear wall design.

General Format

START SHEARWALL DESIGN

CODE INDIAN

FYMAIN f1

FC f2

HMIN f3

HMAX f4

VMIN f5

VMAX f6

EMIN f7

EMAX f8

LMIN f9

LMAX f10

CLEAR f11

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TWOLAYERED f12

KSLENDER f13

DESIGN SHEARWALL LIST shearwall-list

END

The following table explains the parameters used in the shear wall design.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CLEAR 25 mm Clear concrete cover, incurrent units.

EMAX 36 Maximum size of verticalreinforcing bars locatedin edge zones (range6mm – 36mm). If inputis 6 (integer number) theprogram will assume 6mm diameter bar.

EMIN 8 Minimum size of verticalreinforcing bars locatedin edge zones (range6mm – 36mm). If inputis 6 (integer number) theprogram will assume 6mm diameter bar.

FYMAIN 415 Mpa Yield strength of steel, incurrent units.

FC 30 Mpa Compressive strength ofconcrete, in currentunits.

HMIN 8 Minimum size of

Table 9A.2 - Shear Wall Design Parameters

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ParameterName

DefaultValue

Description

horizontal reinforcingbars (range 6 mm – 36mm). If input is 6(integer number) theprogram will assume 6mm diameter bar.

HMAX 36 Maximum size ofhorizontal reinforcingbars (range 6 mm – 36mm). If input is 6(integer number) theprogram will assume 6mm diameter bar.

KSLENDER 1.0 Slenderness factor forfinding effective height.

LMAX 16 Maximum size of links(range 6mm – 16mm). Ifinput is 6 (integernumber) the programwill assume 6 mmdiameter bar.

LMIN 6 Minimum size of links(range 6mm – 16mm). Ifinput is 6 (integernumber) the programwill assume 6 mmdiameter bar.

TWOLAYERED 0 Reinforcementplacement mode:

0. single layer, eachdirection

1. two layers, eachdirection

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ParameterName

DefaultValue

Description

VMAX 36 Maximum size of verticalreinforcing bars (range6mm – 36mm). If inputis 6 (integer number) theprogram will assume 6mm diameter bar.

VMIN 8 Minimum size of verticalreinforcing bars (range6mm – 36mm). If inputis 6 (integer number) theprogram will assume 6mm diameter bar.

The following example illustrates the input for the definition of shear wall anddesign of the wall.

Example

.

.

SET DIVISION 12

SURFACE INCIDENCES

2 5 37 34 SUR 1

19 16 65 68 SUR 2

11 15 186 165 SUR 3

10 6 138 159 SUR 4

.

.

.

SURFACE PROPERTY

1 TO 4 THI 18

SUPPORTS

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1 7 14 20 PINNED

2 TO 5 GEN PIN

6 TO 10 GEN PIN

11 TO 15 GEN PIN

19 TO 16 GEN PIN

.

.

.

SURFACE CONSTANTS

E 2.17185E+007

POISSON 0.17

DENSITY 23.5616

ALPHA 1E-005

.

.

START SHEARWALL DES

CODE INDIAN

UNIT NEWMMS

FC 25

FYMAIN 415

TWO1

VMIN 12

HMIN 12

EMIN 12

DESIGN SHEA LIST 1 TO 4

END

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Notes

1. Command SET DIVISION 12 indicates that the surface boundary node-to-node segments will be subdivided into 12 fragments prior to finite elementmesh generation.

2. Four surfaces are defined by the SURFACE INCIDENCES command.

3. The SUPPORTS command includes the new support generation routine. Forinstance, the line 2 to 5 gen pin assigns pinned supports to all nodesbetween nodes 2 and 5. As the node-to-node distances were previouslysubdivided by the SET DIVISION 12 command, there will be an additional11 nodes between nodes 2 and 5. As a result, all 13 nodes will be assignedpinned supports. Please note that the additional 11 nodes are not individuallyaccessible to the user. They are created by the program to enable the finiteelement mesh generation and to allow application of boundary constraints.

4. Surface thickness and material constants are specified by the SURFACEPROPERTY and SURFACE CONSTANTS, respectively.

5. The shear wall design commands are listed between lines START SHEARWALLDES and END. The CODE command selects the design code that will be thebasis for the design. For Indian code the parameter is INDIAN. The DESIGNSHEARWALL LIST command is followed by a list of previously definedSurface elements intended as shear walls and/or shear wall components.

Technical Overview

The program implements provisions of section 32 of IS 456-2000 and relevantprovisions as referenced therein, for all active load cases. The following steps areperformed for each of the horizontal sections of the wall.

Checking of slenderness limit

The slenderness checking is done as per clause no. 32.2.3. The default effectiveheight is the height of the wall. User can change the effective height. The limit forslenderness is taken as 30.

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Design for in-plane bending and vertical load (denoted by Mz & Fyin the shear wall force output)

Walls when subjected to combined in-plane horizontal and vertical forces producein-plane bending in conjunction with vertical load. According to clause no. 32.3.1,in-plane bending may be neglected in case a horizontal cross section of the wall isalways under compression due combined effect of horizontal and vertical loads.Otherwise, the section is checked for combined vertical load and in-plane momentas column with axial load and uni-axial bending. For this purpose, the depth istaken as 0.8 x horizontal length of wall and breadth is the thickness of the wall.The reinforcement is concentrated at both ends (edges) of the wall. The edgereinforcement is assumed to be distributed over a length of 0.2 times horizontallength on each side. Minimum reinforcements are according to clause no. 32.5.(a).Maximum 4% reinforcement is allowed.

Design for in-plane shear (denoted by Fxy in the shear wall forceoutput)

By default, the program does not design only at the critical section but at all thehorizontal sections. By suitable use of the surface division command, design atcritical section as per clause no. 32.4.1 can be performed.

The design for in-plane shear is done as per clause no. 32.4. The nominal shearstress is calculated as per clause no. 32.4.2 and it is checked with the maximumallowable shear stress as per clause no. 32.4.2.1. The design shear strength ofconcrete is calculated as per clause no. 32.4.3. Design of shear reinforcement isdone as per clause no. 32.4.4. Minimum reinforcements are as per clause no.32.5.

Design for vertical load and out-of-plane vertical bending (denotedby Fy and My respectively in the shear wall force output)

Apart from the in-plane bending and horizontal shear force, the wall is alsosubjected to out-of-plane bending in the vertical and horizontal directions. Thepart of the wall which is not having edge reinforcements (i.e., a zone of depth 0.6x Length of the wall), is designed again as column under axial load (i.e., verticalload) and out-of-plane vertical bending. The minimum reinforcements andmaximum allowable spacings of reinforcements are as per clause no. 32.5

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Design for out-of-plane horizontal bending (denoted by Mx in theshear wall force output)

The horizontal reinforcement which is already provided for in-plane shear ischecked against out-of-plane horizontal bending. The wall is assumed as a slab forthis purpose.

Design for out-of-plane shears (denoted by Qx and Qy in the shearwall force output)

The out-of-plane shear arises from out-of-plane loading. The nominal shearstresses are calculated as per clause no. 40.1. Maximum allowable shear stressesare as per table 20. For shear force in the vertical direction, shear strength ofconcrete section is calculated as per section 4.1 of SP 16 : 1980 considering verticalreinforcement as tension reinforcement. Similarly, for shear force in the horizontaldirection, shear strength of concrete section is calculated considering horizontalreinforcement as tension reinforcement. Shear reinforcements in the form of linksare computed as per the provisions of clause no. 40.4.

Shear  Wall  Design With Opening

The Surface element has been enhanced to allow design of shear walls withrectangular openings. The automatic meshing algorithm has been improved toallow variable divisions along wall and opening(s) edges. Design and output areavailable for user selected locations.

Description

Shear walls modeled in STAAD.Pro may include an unlimited number of openings.Due to the presence of openings, the wall may be comprise of different wall panelsof varying types.

1. Shear wall set-up

Definition of a shear wall starts with a specification of the surface elementperimeter nodes, meshing divisions along node-to-node segments,opening(s) corner coordinates, and meshing divisions of four edges of theopening(s).

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SURFACE INCIDENCE n1, ..., ni SURFACE s DIVISION sd1,..., sdj -

RECOPENING x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4 DIVISIONod1, ..., odk

Where:

n1, … , ni — node numbers on the perimeter of the shear wall,

s — surface ordinal number,

sd1, … , sdj — number of divisions for each of the node-to-nodedistance on the surface perimeter,

x1 y1 z1 (…) — coordinates of the corners of the  opening,

od1, … , odk — divisions along edges of the opening.

Note: If the sd1, … , sdj or the od1, … , odk list does not include allnode-to-node segments, or if any of the numbers listed equals zero, thenthe corresponding division number is set to the default value (=10, or aspreviously input by the SET DIVISION command).

Default locations for stress/force output, design, and design output are setas follows:

SURFACE DIVISION X xd

SURFACE DIVISION Y yd

Where:

xd — number of divisions along X axis,

yd — number of divisions along Y axis.

Note: xd and yd represent default numbers of divisions for each edge ofthe surface where output is requested. The output is provided forsections located between division segments. For example, if the numberof divisions = 2, then the output will be produced for only one section (atthe center of the edge).

2. Stress/force output printing

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Values of internal forces may be printed out for any user-defined section ofthe wall. The general format of the command is as follows:

PRINT SURFACE FORCE (ALONG ξ) (AT a) (BETWEEN d1, d2)LIST s1, … ,si

Where:

ξ — local axis of the surface element (X or Y),

a — distance along the ξ   axis from start of the member to thefull cross-section of the wall,

d1, d2 — coordinates in the direction orthogonal to ξ , delineatinga fragment of the full cross-section for which the output isdesired. **

s1, … ,si — list of surfaces for output generation

** The range currently is taken in terms of local axis. If the local axis isdirected away from the surface, the negative range is to be entered.

Note: If command ALONG is omitted, direction Y (default) is assumed. Ifcommand AT is omitted, output is provided for all sections along thespecified (or default) edge. Number of sections will be determined fromthe SURFACE DIVISION X or SURFACE DIVISION Y input values. If theBETWEEN command is omitted, the output is generated based on fullcross-section width.

3. Definition of wall panels

Input syntax for panel definition is as follows:

START PANEL DEFINITION

SURFACE i PANEL j ptype x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4z4

END PANEL DEFINITION

Where:

i = ordinal surface number,

j = ordinal panel number,

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ptype = panel type, one of: WALL, COLUMN, BEAM

x1 y1 z1 (…) = coordinates of the corners of the panel,

4. Shear wall design

The program implements different provisions of design of walls as per codeBS 8110. General syntax of the design command is as follows:

START SHEARWALL DESIGN

(…)

DESIGN SHEARWALL (AT f2) LIST s

ENDSHEARWALL DESIGN

Note: If the command AT is omitted, the design proceeds for all crosssections of the wall or panels, as applicable, defined by the SURFACEDIVISION X or SURFACE DIVISION Y input values.

a. No panel definition.

Design is performed for the specified horizontal full cross-section,located at a distance c from the origin of the local coordinates system.If opening is found then reinforcement is provided along sides ofopenings. The area of horizontal and vertical bars provided alongedges of openings is equal to that of the respective interrupted bars.

b. Panels have been defined.

Only wall panel design is supported in Indian code.

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Indian Codes - Concrete Design per IS139209A1.1 Design Operations

Earthquake motion often induces force large enough to cause inelasticdeformations in the structure. If the structure is brittle, sudden failure could occur.But if the structure is made to behave ductile, it will be able to sustain theearthquake effects better with some deflection larger than the yield deflection byabsorption of energy. Therefore ductility is also required as an essential element forsafety from sudden collapse during severe shocks.

STAAD has the capabilities of performing concrete design as per IS 13920. Whiledesigning it satisfies all provisions of IS 456 – 2000 and IS 13920 for beams andcolumns.

9A1.2   Section  Types  for  Concrete  Design

The following types of cross sections for concrete members can be designed.

l For Beams: Prismatic (Rectangular & Square) and T-shape

l For Columns : Prismatic (Rectangular, Square, and Circular)

9A1.3 Design Parameters

The program contains a number of parameters that are needed to perform designas per IS 13920. It accepts all parameters that are needed to perform design as perIS:456. Over and above it has some other parameters that are required only whendesigned is performed as per IS:13920.  Default parameter values have beenselected such that they are frequently used numbers for conventional designrequirements. These values may be changed to suit the particular design beingperformed. Table 8A1.1 of this manual contains a complete list of the availableparameters and their default values. It is necessary to declare length and force unitsas Millimeter and Newton before performing the concrete design.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CODE - Must be specified as IS13920

Design Code to follow.

See section 5.52.2 of the TechnicalReference Manual.

BRACING 0.0 Beam Design

1.0 = the effect of axialforce will be taken intoaccount for beamdesign.

Column Design

Correspond to theterms "Braced" and"Unbraced" describedin Notes 1, 2, and 3 ofClause 39.7.1 ofIS456:2000.

1.0 = the column isunbraced about majoraxis.

2.0 = the column isunbraced about minoraxis.

3.0 = the column isunbraced about bothaxis.

DEPTH YD Total depth to be used for design.This value defaults to YD (depth ofsection in Y direction) as providedunder MEMBER PROPERTIES.

CLEAR 25 mm For beammembers.

Table 9A1.1 - Indian Concrete Design IS 13920 Parameters

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ParameterName

DefaultValue

Description

40 mm For column members

COMBINE 0.0 Default value means there will beno member combination.

1.0 = no printout ofsectional force andcritical load forcombined member inthe output.

2.0 = printout ofsectional force forcombined member inthe output.

3.0 = printout of bothsectional force andcritical load forcombined member inthe output. ***

EFACE 0.0 Face of support location at end ofbeam. The parameter can also beused to check against shear at anypoint from the end of the member.

Note: Both SFACE and EFACEare input as positive numbers.*

ELZ 1.0 Ratio of effective length to actuallength of column about major axis.

ELY 1.0 Ratio of effective length to actuallength of column about minor axis.

ENSH 0.0 Perform shear check againstenhanced shear strength as per Cl.40.5 of IS456:2000.

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ParameterName

DefaultValue

Description

1.0 = ordinary shearcheck to be performed (no enhancement ofshear strength atsections close tosupport)

a positive value(say x )= shear strength will beenhanced up to adistance x from thestart of the member.This is used only whena span of a beam issubdivided into two ormore parts. (Refer noteafter Table 8A.1 )

a negative value(say –y) = shear strength willbe enhanced up to adistance y from the endof the member. This isused only when a spanof a beam is subdividedinto two or moreparts.(Refer note afterTable 8A.1)

0.0 = the program willcalculate Length toOverall Depth ratio. Ifthis ratio is greater than2.5, shear strength willbe enhanced at sections(<2d) close to supportotherwise ordinaryshear check will beperformed.

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ParameterName

DefaultValue

Description

EUDL None Equivalent u.d.l on span of thebeam. This load value must be theunfactored load on span. Duringdesign the load value is multipliedby a factor 1.2. If no u.d.l isdefined factored shear force due togravity load on span will be takenas zero. No elastic or plasticmoment will be calculated. Sheardesign will be performed based onanalysis result.(Refer note)

FYMAIN 415 N/mm2 Yield Stress for main reinforcingsteel.

FYSEC 415 N/mm2 Yield Stress for secondaryreinforcing steel.

FC 30 N/mm2 Concrete Yield Stress.

GLD None Gravity load number to beconsidered for calculatingequivalent u.d.l on span of thebeam, in case no EUDL ismentioned in the input. Thisloadcase can be any static loadcasecontainingMEMBER LOAD on thebeam which includes UNI, CON,LIN and TRAP member loading.CMOMmember loading isconsidered only when it is specifiedin local direction. FLOOR LOAD isalso considered.

The load can be primary orcombination load. For combinationload only load numbers included inload combination is considered.The load factors are ignored.

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ParameterName

DefaultValue

Description

Internally the unfactored load ismultiplied by a factor 1.2 duringdesign.

If both EUDL and GLD parametersare mentioned in the inputmentioned EUDL will be consideredin design

Note: No dynamic (Responsespectrum, 1893, Time History)and moving load cases areconsidered.

CMOM member loading in globaldirection is not considered.

UMOM member loading is notconsidered.

HLINK Spacing oflongitudinal

barsmeasured tothe outerface

Longer dimension of therectangular confining hoopmeasured to its outer face. It shallnot exceed 300 mm as per Cl.7.4.8. If the HLINK value asprovided in the input file does notsatisfy the clause the value will beinternally assumed as the defaultone. This parameter is valid forrectangular column.

IPLM 0.0 Default value calculateselastic/plastic hogging and saggingmoments of resistance of beam atits ends.

1.0 = calculation ofelastic/plastic hoggingand sagging moments

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ParameterName

DefaultValue

Description

of resistance of beam tobe ignored at startnode of beam. Thisimplies no supportexists at start node.

-1.0 = calculation ofelastic/plastic hoggingand sagging momentsof resistance of beam tobe considered at startnode of beam. . Thisimplies support existsat start node.

2.0 = calculation ofelastic/plastic hoggingand sagging momentsof resistance of beam tobe ignored at end nodeof beam. This impliesno support exists atend node.

-2.0 = calculation ofelastic/plastic hoggingand sagging momentsof resistance of beam tobe considered at endnode of beam. . Thisimplies support existsat end node. **

IMB 0.0 Default value calculateselastic/plastic hogging and saggingmoments of resistance of beam atits ends.

1.0 = calculation of

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ParameterName

DefaultValue

Description

elastic/plastic hoggingand sagging momentsof resistance of beam tobe ignored at both endsof beam. This impliesno support exist ateither end of themember.

-1.0 = calculation ofelastic/plastic hoggingand sagging momentsof resistance of beam tobe considered at bothends of beam. Thisimplies support exist atboth ends of themember.**

MINMAIN 10 mm Minimummain reinforcement barsize.

MAXMAIN 60 mm Maximummain reinforcement barsize.

MINSEC 8 mm Minimum secondary reinforcementbar size.

MAXSEC 12 mm Maximum secondary reinforcementbar size.

PLASTIC 0.0 Default value calculates elastichogging and sagging moments ofresistance of beam at its ends.

1.0 = plastic hoggingand sagging momentsof resistance of beam tobe calculated at itsends.

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ParameterName

DefaultValue

Description

RATIO 4.0 Maximum percentage oflongitudinal reinforcement incolumns.

REINF 0.0 0.0 = Tied column (default)

1.0 = spiral reinforcement

RENSH 0.0 Distance of the start or end point ofthe member from its nearestsupport. This parameter is usedonly when a span of a beam issubdivided into two or more parts.

Refer note after Table 9A.1

RFACE 4.0 4.0 = longitudinal reinforcement incolumn is arranged equally alongfour faces.

2.0 invokes two faced distributionabout major axis.

3.0 invokes two faced distributionabout minor axis.

SFACE 0.0 Face of support location at start ofbeam. It is used to check againstshear at the face of the support inbeam design. The parameter canalso be used to check against shearat any point from the start of themember.*

Note: Both SFACE and EFACEare input as positive numbers.*

SPSMAIN 25 mm Minimum clear distance betweenmain reinforcing bars in beam andcolumn. For column center to

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ParameterName

DefaultValue

Description

center distance between main barscannot exceed 300 mm.

TORISION 0.0 0.0 = torsion to be considered inbeam design.

1.0 = torsion to be neglected inbeam design.

TRACK 0.0 Beam Design:

0.0 = output consistsof reinforcement detailsat START, MIDDLE andEND.

1.0 = critical momentsare printed in additionto TRACK 0.0 output.

2.0 = required steel forintermediate sectionsdefined by NSECTIONare printed in additionto TRACK 1.0 output.

Column Design:

0.0 = reinforcementdetails are printed.

1.0 = columninteraction analysisresults are printed inaddition to TRACK 0.0output.

2.0 = a schematicinteraction diagram andintermediate interactionvalues are printed in

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ParameterName

DefaultValue

Description

addition to TRACK 1.0output.

ULY 1.0 Ratio of unsupported length toactual length of column aboutminor axis.

ULZ 1.0 Ratio of unsupported length toactual length of column aboutmajor axis.

WIDTH ZD Width to be used for design. Thisvalue defaults to ZD as providedunder MEMBER PROPERTIES.

Bar combination has been introduced for detailing. Please refer section 9A1.6 fordetails.

* EFACE and SFACE command is not valid for member combination.

** IPLM and IMB commands are not valid for member combination. Thesecommands are ignored for members forming physical member.

*** The purpose of COMBINE command is the following:

1. If a beam spanning between two supports is subdivided into many sub-beams this parameter will combine them into one member. It can also beused to combine members to form one continuous beam spanning over morethan two supports.

2. When two or more members are combined during design plastic or elasticmoments will be calculated at the column supports. At all the intermediatenodes (if any) this calculation will be ignored.

Note: Please note that the program only recognizes column at right angleto the beam. Inclined column support is ignored.

3. It will calculate sectional forces at 13 sections along the length of thecombined member.

4. It will calculate critical loads (similar to that of Design Load Summary) for all

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active load cases during design.

Beams will be combined only when DESIGN BEAM command is issued.

The following lines should be satisfied during combination of members:

1. Members to be combined should have same sectional properties if any singlespan between two column supports of a continuous beam is subdivided intoseveral members.

2. Members to be combined should have same constants (E, Poi ratio, alpha,density, and beta angle)

3. Members to be combined should lie in one straight line.

4. Members to be combined should be continuous.

5. Vertical members (i.e., columns) cannot be combined.

6. Same member cannot be used more than once to form two differentcombined members.

7. The maximum number of members that can be combined into one member is299.

Note: Sectional forces and critical load for combined member output will onlybe available when all the members combined are successfully designed in bothflexure and shear.

ENSH and RENSH parameters will have to be provided (as and when necessary)even if physical member has been formed.

Example

The following lines show a standard example for design to be performed in IS13920.

STAAD SPACE

UNIT METERMTON

JOINT COORDINATES

…………………………………..

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MEMBER INCIDENCES

…………………………………..

MEMBER PROPERTY INDIAN

…………………………………..

CONSTANTS

…………………….

SUPPORTS

…………………….

DEFINE 1893 LOAD

ZONE 0.05 I 1 K 1 B 1

SELFWEIGHT

JOINT WEIGHT

……………………….

LOAD 1 SEISMIC LOAD IN X DIR

1893 LOAD X 1

LOAD 2 SEISMIC LOAD IN Z DIR

1893 LOAD Z 1

LOAD 3 DL

MEMBER LOAD

……UNIGY -5

LOAD 4 LL

MEMBER LOAD

…….UNIGY -3

LOAD COMB 5 1.5(DL+LL)

3 1.5 4 1.5

LOAD COMB 6 1.2(DL+LL+SLX)

1 1.2 3 1.2 4 1.2

LOAD COMB 7 1.2(DL+LL-SLX)

1 1.2 3 1.2 4 -1.2

LOAD COMB 8 1.2(DL+LL+SLZ)

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2 1.2 3 1.2 4 1.2

LOAD COMB 9 1.2(DL+LL-SLZ)

2 1.2 3 1.2 4 -1.2

PDELTA ANALYSIS

LOAD LIST 5 TO 9

START CONCRETEDESIGN

CODE IS13920

UNIT MMSNEWTON

FYMAIN 415 ALL

FC 20 ALL

MINMAIN 12 ALL

MAXMAIN 25 ALL

TRACK 2.0 ALL

*** UNFACTORED GRAVITY LOAD ON MEMBERS 110 TO 112 IS 8T/M (DL+LL) I.E., 78.46 NEW/MM

EUDL 78.46 MEMB 110 TO 112

** MEMBERS TOBE COMBINED INTOONE PHYSICALMEMBER

COMBINE 3.0 MEMB 110 TO 112

*** PLASTIC MOMENT CONSIDERED

PLASTIC 1.0 MEMB 110 TO 112

DESIGN BEAM 110 TO 112

DESIGN COLUMN………

END CONCRETEDESIGN

FINISH

9A1.4 Beam Design

Beams are designed for flexure, shear and torsion. If required the effect of theaxial force may be taken into consideration. For all these forces, all active beamloadings are prescanned to identify the critical load cases at different sections ofthe beams. The total number of sections considered is 13. All of these sections arescanned to determine the design force envelopes.

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For design to be performed as per IS:13920 the width of the member shall not beless than 200mm(Clause 6.1.3). Also the member shall preferably have a width-todepth ratio of more than 0.3 (Clause 6.1.2).

The factored axial stress on the member should not exceed 0.1fck (Clause 6.1.1)for all active load cases. If it exceeds allowable axial stress no design will beperformed.

Design  for  Flexure

Design procedure is same as that for IS 456. However while designing followingcriteria are satisfied as per IS-13920:

1. The minimum grade of concrete shall preferably be M20. (Clause 5.2)

2. Steel reinforcements of grade Fe415 or less only shall be used. (Clause 5.3)

3. The minimum tension steel ratio on any face, at any section, is given by(Clause 6.2.1b)

ρmin

= 0.24Öfck/fy

The maximum steel ratio on any face, at any section, is given by (Clause6.2.2)

ρmax

= 0.025

4. The positive steel ratio at a joint face must be at least equal to half thenegative steel at that face. (Clause 6.2.3)

5. The steel provided at each of the top and bottom face, at any section, shall atleast be equal to one-fourth of the maximum negative moment steel providedat the face of either joint. (Clause 6.2.4)

Design  for  Shear

The shear force to be resisted by vertical hoops is guided by the Clause 6.3.3 of IS13920:1993 revision. Elastic sagging and hogging moments of resistance of thebeam section at ends are considered while calculating shear force. Plastic saggingand hogging moments of resistance can also be considered for shear design ifPLASTIC parameter is mentioned in the input file. (Refer Table 8A1.1)

Shear reinforcement is calculated to resist both shear forces and torsionalmoments. Procedure is same as that of IS 456.

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The following criteria are satisfied while performing design for shear as per Cl.6.3.5 of IS-13920:

The spacing of vertical hoops over a length of 2d at either end of the beam shallnot exceed

a. d/4

b. 8 times the diameter of the longitudinal bars

In no case this spacing is less than 100 mm.

The spacing calculated from above, if less than that calculated from IS 456consideration is provided.

Beam Design Output

The default design output of the beam contains flexural and shear reinforcementprovided at 5 equally spaced sections along the length of the beam. User hasoption to get a more detail output. All beam design outputs are given in IS units.An example of rectangular beam design output with the TRACK 2.0 is presentedbelow:

B E A M N O. 1 D E S I G N R E S U L T S

M20 Fe415 (Main) Fe250(Sec.)

LENGTH: 6400.0 mm SIZE: 300.0 mm X 400.0 mm COVER:25.0 mm

DESIGN LOAD SUMMARY (KN MET)-------------------------------------------------------------------

---------SECTION |FLEXURE (Maxm. Sagging/Hogging moments)| SHEAR(in mm) | P MZ MX Load Case | VY MX

Load Case-------------------------------------------------------------------

---------0.0 | 0.00 0.00 0.00 1 | 60.61 0.00

1| 0.00 0.00 0.00 1 |

533.3 | 0.00 29.63 0.00 1 | 50.51 0.001

| 0.00 0.00 0.00 1 |1066.7 | 0.00 53.88 0.00 1 | 40.41 0.001

| 0.00 0.00 0.00 1 |1600.0 | 0.00 72.73 0.00 1 | 30.31 0.001

| 0.00 0.00 0.00 1 |

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2133.3 | 0.00 86.20 0.00 1 | 20.20 0.001

| 0.00 0.00 0.00 1 |2666.7 | 0.00 94.28 0.00 1 | 10.10 0.001

| 0.00 0.00 0.00 1 |3200.0 | 0.00 96.98 0.00 1 | 0.00 0.001

| 0.00 0.00 0.00 1 |3733.3 | 0.00 94.28 0.00 1 | -10.10 0.001

| 0.00 0.00 0.00 1 |4266.7 | 0.00 86.20 0.00 1 | -20.20 0.001

| 0.00 0.00 0.00 1 |4800.0 | 0.00 72.73 0.00 1 | -30.31 0.001

| 0.00 0.00 0.00 1 |5333.3 | 0.00 53.88 0.00 1 | -40.41 0.001

| 0.00 0.00 0.00 1 |5866.7 | 0.00 29.63 0.00 1 | -50.51 0.001

| 0.00 0.00 0.00 1 |6400.0 | 0.00 0.00 0.00 1 | -60.61 0.001

| 0.00 0.00 0.00 1 |*** DESIGN SHEAR FORCE AT SECTION 0.0 IS 60.61 KN.

- CLAUSE 6.3.3 OF IS-13920

*** DESIGN SHEAR FORCE AT SECTION 6400.0 IS 60.61 KN.- CLAUSE 6.3.3 OF IS-

13920NOTE :

MOMENT OF RESISTANCE IS CALCULATED BASED ON THE AREA OF STEEL PRO-VIDED.

IF AREA OF STEEL PROVIDED IS MUCH HIGHER COMPARED TO AREA OF STEELREQUIRED MOMENT OF RESISTANCE WILL INCREASE WHICH MAY INCREASE

DESIGNSHEAR FORCE.--------------------------------------------------------------------

--------STAAD SPACE -- PAGE

NO. 70.0 | 0.00/ 402.12( 2-16í )| 0.00/ 981.75( 2-25í )| 8í @

100 mm533.3 | 0.00/ 402.12( 2-16í )| 281.26/1472.62( 3-25í )| 8í @

180 mm1066.7 | 0.00/ 402.12( 2-16í )| 450.84/1472.62( 3-25í )| 8í @

180 mm1600.0 | 0.00/ 402.12( 2-16í )| 632.82/1472.62( 3-25í )| 8í @

180 mm

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2133.3 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )| 8í@ 180 mm

2666.7 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )| 8í@ 180 mm

3200.0 | 0.00/ 402.12( 2-16í )| 894.99/1472.62( 3-25í )| 8í@ 180 mm

3733.3 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )| 8í@ 180 mm

4266.7 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )| 8í@ 180 mm

4800.0 | 0.00/ 402.12( 2-16í )| 632.82/1472.62( 3-25í )| 8í@ 180 mm

5333.3 | 0.00/ 402.12( 2-16í )| 450.84/1472.62( 3-25í )| 8í@ 180 mm

5866.7 | 0.00/ 402.12( 2-16í )| 281.26/1472.62( 3-25í )| 8í@ 180 mm

6400.0 | 0.00/ 402.12( 2-16í )| 0.00/ 981.75( 2-25í )| 8í@ 100 mm

----------------------------------------------------------------------------

9A1.5   Column  Design

Columns are designed for axial forces and biaxial moments per IS 456:2000.Columns are also designed for shear forces as per Clause 7.3.4. All major criteriafor selecting longitudinal and transverse reinforcement as stipulated by IS:456have been taken care of in the column design of STAAD. However followingclauses have been satisfied to incorporate provisions of IS 13920:

l The minimum grade of concrete shall preferably be M20. (Clause 5.2)  

l Steel reinforcements of grade Fe415 or less only shall be used. (Clause 5.3)      

l The minimum dimension of column member shall not be less than 200 mm.For columns having unsupported length exceeding 4m, the shortestdimension of column shall not be less than 300 mm. (Clause 7.1.2)

l The ratio of the shortest cross-sectional dimension to the perpendiculardimension shall preferably be not less than 0.4. (Clause 7.1.3)

l The spacing of hoops shall not exceed half the least lateral dimension of thecolumn, except where special confining reinforcement is provided. (Clause7.3.3)

l Special confining reinforcement shall be provided over a length lofrom each

joint face, towards mid span, and on either side of any section, where

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flexural yielding may occur. The length loshall not be less than a) larger

lateral dimension of the member at the section where yielding occurs, b) 1/6of clear span of the member, and c) 450 mm. (Clause 7.4.1)

l The spacing of hoops used as special confining reinforcement shall notexceed ¼ of minimummember dimension but need not be less than 75 mmnor more than 100 mm. (Clause 7.4.6)

l The area of cross-section of hoops provided are checked against theprovisions for minimum area of cross-section of the bar forming rectangular,circular or spiral hoops, to be used as special confining reinforcement.(Clause 7.4.7 and 7.4.8)

Column  Design  Output

Default column design output (TRACK 0.0) contains the reinforcement provided bySTAAD and the capacity of the section. With the option TRACK 1.0, the outputcontains intermediate results such as the design forces, effective length coefficients,additional moments etc. A special output TRACK 9.0 is introduced to obtain thedetails of section capacity calculations. All design output is given in SI units. Anexample of a column design output (with option TRACK 1.0) is given below.

========================================================================-====

C O L U M N   N O.      3  D E S I G N   R E S U L T SM20                   

Fe415 (Main)              Fe415 (Sec.)

LENGTH:  3000.0 mm   CROSS SECTION: 350.0 mm X  400.0 mm  COVER: 40.0 mm

** GUIDING LOAD CASE:   5 END JOINT:   2  SHORT COLUMN

DESIGN FORCES (KNS-MET)-----------------------DESIGN AXIAL FORCE (Pu)            

:   226.7About Z       

About YINITIAL MOMENTS                    

:    0.64         146.28

MOMENTS DUE TO MINIMUM ECC.        :    4.53            4.53

SLENDERNESS RATIOS                 :     -              

-

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MOMENTS DUE TO SLENDERNESS EFFECT   :    -              

-MOMENT REDUCTION FACTORS           

:     -              -

ADDITION MOMENTS (Maz and May)     :     -              

-TOTAL DESIGN MOMENTS               

:    4.53         146.28

** GUIDING LOAD CASE:   5

Along Z         Along YDESIGN SHEAR FORCES                

:   43.31          76.08

REQD. STEEL AREA   :   3313.56 Sq.mm.MAIN REINFORCEMENT : Provide  12 - 20 dia.

(2.69%,   3769.91 Sq.mm.)

(Equally distributed)CONFINING REINFORCEMENT  : Provide 10 mm dia.

rectangular ties @  85 mm c/cover a length   500.0 mm from each joint face towards

                      midspan as per Cl. 7.4.6 of IS-13920.TIE REINFORCEMENT       

: Provide 10 mm dia. rectangular ties @ 175 mm c/cSECTION CAPACITY (KNS-MET)--------------------------Puz :   2261.52   Muz1 :   

178.71   Muy1 :    150.75INTERACTION RATIO: 1.00 (as per Cl. 39.6, IS456:2000)=======================================================================-=====********************END OF COLUMN DESIGN RESULTS********************

9A1.6 Bar Combination

Initially the program selects only one bar to calculate the number of bars requiredand area of steel provided at each section along the length of the beam. You mayuse the BAR COMBINATION command to specify two bar diameters to calculate acombination of each bar to be provided at each section. The syntax for barcombination is given below.

START BAR COMBINATION

MD1 <bar diameter> MEMB <member list>

MD2 <bar diameter> MEMB <member list>

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ENDBAR COMBINATION

Note: The bar sizes should be specified in the order of increasing size (i.e., MD2bar diameter should be greater than MD1 bar diameter).

The beam length is divided into three parts, two at its ends and one at span. Ldgives the development length to be provided at the two ends of each section.

The typical output for bar combination is shown below:

OUTPUT FOR BAR COMBINATION

----------------------------------------------------------------------------

| M A I N R E I N F O R C E M E N T|

----------------------------------------------------------------------------

SECTION | 0.0- 1600.0 | 1600.0- 4800.0 | 4800.0-6400.0 |

| mm | mm | mm|

----------------------------------------------------------------------------

TOP | 2-16í | 2-16í | 2-16í|

| in 1 layer(s) | in 1 layer(s) | in 1layer(s) |

Ast Reqd| 0.00 | 0.00 | 0.00|Prov| 402.29 | 402.29 | 402.29|

Ld (mm) | 752.2 | 1175.3 | 752.2|

----------------------------------------------------------------------------

BOTTOM | 4-16í | 2-16í + 2-25í | 4-16í|

| in 1 layer(s) | in 1 layer(s) | in 1layer(s) |

Ast Reqd| 632.82 | 894.99 | 632.82|Prov| 804.57 | 1384.43 | 804.57|

Ld (mm) | 752.2 | 1175.3 | 752.2|

----------------------------------------------------------------------------

============================================================================

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Verification Example

Sample example showing calculation of design shear force as per Clause 6.3.3

Figure 9.1 - Example problem

For Beam No. 1 and 2

Section width, b = 250 mm and depth, D = 500 mm

Characteristic strength of steel, fy = 415 N/mm2

Characteristic strength of concrete, fck = 20 N/mm2

Clear cover = 25 mm

Bar diameter = 12 mm

Effective depth, d = 469 mm

Eudl, w = 6.5 N/mm2

Length, L = 4,000 mm

Ast_Top_A

= 339.29 mm2

Ast_Bot_A

= 226.19 mm2

Ast_Top_B

= 226.19 mm2

Ast_Bot_B

= 339.29 mm2

Steps

Calculation of Simple Shear

Simple shear from

gravity load on span =

Va = Vb = 1.2 * w * L / 2 = 15600N

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Calculation of Moment Of Resistances Based On Area Of Steel Provided

Sagging Moment Of

Resistance of End A

Mu, as =

0.87 * fy * Ast_Bot_A * d *

( 1 - Ast_Bot_A * fy / b * d * fck) 

= 36768130.05

N

Hogging Moment Of

Resistance of End A

Micah =

0.87 * fy * Ast_Top_A * d *

( 1 - Ast_Top_A * fy / b * d * fck) 

= 54003057.45

N

Sagging Moment Of

Resistance of End A

Mu, bs =

0.87 * fy * Ast_Bot_B * d *

( 1 - Ast_Bot_B * fy / b * d * fck) 

= 54003057.45

N

Hogging Moment Of

Resistance of End A

Mob =

0.87 * fy * Ast_Top_B * d * ( 1 - Ast_

Top_B* fy / b * d * fck) 

= 36768130.05

N

Calculation of shear force due to the formation of a plastic hinge at both ends of thebeam plus the factored gravity load on the span.

Figure 9.2 - Sway to right

FIG1:  SWAY TO RIGHT

Vur,a   =   Va - 1.4 [ ( Mu,as + Mu,bh ) / L ] =  -10137.69104

N

Vur,b   =   Va + 1.4 [ ( Mu,as + Mu,bh ) / L ] =  41337.69104

NFigure 9.3 - Sway to left

Vul,a   =   Va + 1.4 [ ( Mu,ah + Mu,bs ) / L 53402.14022 N

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]  = 

Vul,b   =   Va - 1.4 [ ( Mu,ah + Mu,bs ) / L ]

=

- 22202.14022 N

Design Shear Force

Shear Force From Analysis At End A , Va,anl  = 11.56 N

Design Shear Force At End A, Vu,a = Max ( Va,anl, Vur,a, Vul,a) 

=

53402.14022

N

Shear Force From Analysis At End B , Vb,anl  = -6.44 N

Design Shear Force At End B, Vu,b = Max ( Vb,anl, Vur,b, Vul,b) 

=

41337.69104N

For Beam No. 3

Section   Width b 300 mm

Depth D  450 mm

Characteristic Strength of Steel fy 415 N/sq. mm

Characteristic Strength of Concrete fck 20 N/sq. mm

Clear Cover 25 mm

Bar Diameter 12 mm

Effective Depth d 419 mm

Eudl w 6.5 N/sq. mm

Length L 3000 mm

Ast_Top_A 226.19 sq. mm

Ast_Bot_A 339.29 sq. mm

Ast_Top_B 452.39 sq. mm

Ast_Bot_B 226.19 sq. mm

Calculation of Simple Shear

Simple shear from

gravity load on span

=

Va = Vb = 1.2 * w * L / 2 = 11700N

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Calculation of Moment Of Resistances Based On Area Of Steel Provided

Sagging Moment Of

Resistance of End A

Mu,as =

0.87 * fy * Ast_Bot_A * d *

( 1 - Ast_Bot_A * fy / b * d * fck) 

= 48452983

N

Hogging Moment Of

Resistance of End A

Mu,ah =

0.87 * fy * Ast_Top_A * d *

( 1 - Ast_Top_A * fy / b * d * fck) 

=

32940364.5

N

Sagging Moment Of

Resistance of End A

Mu,bs =

0.87 * fy * Ast_Bot_B * d *

( 1 - Ast_Bot_B * fy / b * d * fck) 

=

32940364.5

N

Hogging Moment Of

Resistance of End A

Mu,bh =

0.87 * fy * Ast_Top_B * d * ( 1 - Ast_Top_

B* fy / b * d * fck) 

=

63326721.3

N

Calculation of shear force due to the formation of a plastic hinge at both ends of thebeam plus the factored gravity load on the span.

Figure 9.4 - Sway to right

Vur,a   =   Va - 1.4 [ ( Mu,as + Mu,bh ) / L ] =  -40463.862

N

Vur,b   =   Va + 1.4 [ ( Mu,as + Mu,bh ) / L ] =  63863.862 N

Sway to left

Vul,a   =   Va + 1.4 [ ( Mu,ah + Mu,bs ) / L ]  =  42444.3402

N

Vul,b   =   Va - 1.4 [ ( Mu,ah + Mu,bs ) / L ] = -15144.34 N

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Design Shear Force

Shear Force From Analysis At End A , Va,anl  = -10.31 N

Design Shear Force At End A, Vu,a = Max (

Va,anl, Vur,a, Vul,a)  =

42444.3402 N

Shear Force From Analysis At End B , Vb,anl  = -23.81 N

Design Shear Force At End B, Vu,b = Max (

Vb,anl, Vur,b, Vul,b)  =

63863.862 N

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Indian Codes - Steel Design per IS800:19849B.1 Design Operations

STAAD contains a broad set of facilities for designing structural members asindividual components of an analyzed structure. The member design facilitiesprovide the user with the ability to carry out a number of different designoperations. These facilities may be used selectively in accordance with therequirements of the design problem. The operations to perform a design are:

l Specify the members and the load cases to be considered in the design.

l Specify whether to perform code checking or member selection.

l Specify design parameter values, if different from the default values.

l Specify whether to perform member selection by optimization.

These operations may be repeated by the user any number of times dependingupon the design requirements. The entire ISI steel section table is supported.Section 9B.13 describes the specification of steel sections.

9B.2 General Comments

This section presents some general statements regarding the implementation ofIndian Standard code of practice (IS:800-1984) for structural steel design inSTAAD. The design philosophy and procedural logistics for member selection andcode checking are based upon the principles of allowable stress design. Two majorfailure modes are recognized: failure by overstressing, and failure by stabilityconsiderations. The flowing sections describe the salient features of the allowablestresses being calculated and the stability criteria being used. Members areproportioned to resist the design loads without exceeding the allowable stressesand the most economic section is selected on the basis of least weight criteria. Thecode checking part of the program checks stability and strength requirements andreports the critical loading condition and the governing code criteria. It is generallyassumed that the user will take care of the detailing requirements like provision ofstiffeners and check the local effects such as flange buckling and web crippling.

9B.3 Allowable Stresses

The member design  and code checking in STAAD are based upon the allowablestress design method as per IS:800 (1984). It is a method for proportioning

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structural members using design loads and forces, allowable stresses, and designlimitations for the appropriate material under service conditions. It would not bepossible to describe every aspect of IS:800 in this manual. This section, however,will discuss the salient features of the allowable stresses specified by IS:800 andimplemented in STAAD. Appropriate sections of IS:800 will be referenced duringthe discussion of various types of allowable stresses.

l Axial Stress

l Bending Stress

l Shear Stress

l Combined Stress

9B.3.1   Axial  Stress

Tensile Stress

The allowable tensile stress, as calculated in STAAD as per IS:800 is describedbelow.

The permissible stress in axial tension, σatin MPa on the net effective area of the

sections shall not exceed

σat= 0.6·f

y

Where:

fy= minimum yield stress of steel in Mpa

Compressive Stress

Allowable compressive stress on the gross section of axially loaded compressionmembers shall not exceed 0.6·f

ynor the permissible stress s

accalculated based on

the following equation (per Clause: 5.1.1):

σac= 0.6{( f

cc· fy)/[( f

cc)n + (f

y)n]1/n}

Where:

σac= Permissible stress in axial compression, in Mpa

fy= Yield stress of steel, in Mpa

fcc= Elastic critical stress in compression = π2 E/λ2

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E = Modulus of elasticity of steel, 2 X 105 Mpa

λ=l/r = Slenderness ratio of the member, ratio of the effective length toappropriate radius of gyration

n = A factor assumed as 1.4.

9B.3.2   Bending  Stress

The allowable bending stress in a member subjected to bending is calculated basedon the following formula: (Clause: 6.2.1)

σbt or σ

bc =  0.66 f

y

Where:

σbt= Bending stress in tension

σbc= Bending stress in compression

fy= Yield stress of steel, in MPa

For an I-beam or channel with equal flanges bent about the axis of maximumstrength (z-z axis), the maximum bending compressive stress on the extreme fibrecalculated on the effective section shall not exceed the values of maximumpermissible bending compressive stress. The maximum permissible bendingcompressive stress shall be obtained by the following formula: (Clause: 6.2.2)

Clause 6.2.3

Where:

fy   = Yield stress of steel, in Mpa

n = A factor assumed as 1.4.

fcb= Elastic critical stress in bending, calculated by the following

formula:

Where:

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in MPa

k1

=   a coefficient to allow for reduction in thickness or breadth offlanges between points of effective lateral restraint and depends on y,the ratio of the total area of both flanges at the point of least bendingmoment to the corresponding area at the point of greatest bendingmoment between such points of restraint.

k2

=   a coefficient to allow for the inequality of flanges, anddepends on w, the ratio of the moment of inertia of the compressionflange alone to that of the sum of the moment of the flanges eachcalculated about its own axis parallel to the y-yaxis of the girder, at thepoint of maximum bending moment.

1         =  effective length of compression flange

ry

=   radius of gyration of the section about its axis ofminimum strength (y-y axis)

T        =   mean thickness of the compression flange, is equal to thearea of horizontal portion of flange divided by width.

D        =   overall depth of beam

c1,c2=  respectively the lesser and greater distances from the section

neutral axis to the extreme fibres.

9B.3.3 Shear Stress

Allowable shear stress calculations are based on Section 6.4 of IS:800. For shearon the web, the gross section taken into consideration consist of the product of thetotal depth and the web thickness. For shear parallel to the flanges, the grosssection is taken as 2/3 times the total flange area. 

9B.3.4   Combined  Stress

Members subjected to both axial and bending stresses are proportionedaccordingly to section 7 of IS:800. All members subject to bending and axial

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compression are required to satisfy the equation of Section 7.1.1.(a) forintermediate points, and equation of Section 7.1.1.(b) for support points.

For combined axial tension and bending the equation of Section 7.1.2. is requiredto be satisfied.

Cm coefficients are calculated according to the specifications of Section 7.1.3.information regarding occurrence of sidesway can be provided through the use ofparameters SSY and SSZ. In the absence of any user provided information,sidesway will be assumed.

9B.4 Design Parameters

In STAAD implementation of IS:800, the user is allowed complete control of thedesign process through the use of design parameters. Available design parametersto be used in conjunction with IS:800 are listed in Table 7B.1 of this section alongwith their default values and applicable restrictions. Users should note that whenthe TRACK parameter is set to 1.0 and use in conjunction with this code, allowablebending stresses in compression (FCY & FCZ), tension (FTY & FTZ), and allowableshear stress (FV) will be printed out in Member Selection and Code Check output inMpa. When TRACK is set to 2.0, detailed design output will be provided.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

Default Value Description

CODE - Must be specified asINDIAN

Design Code to follow.

See section 5.48.1 of theTechnical ReferenceManual.

BEAM 3.0 0.0 =  design only for endmoments and those atlocations specified by theSECTION command.

Table 9B.1 - Indian Steel Design IS 800:1984 Parameters

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ParameterName

Default Value Description

1.0 = calculate sectionforces at twelfth pointsalong the beam, design ateach intermediate locationand report the criticallocation where ratio ismaximum.

CMY

CMZ

0.85 forsidesway andcalculated for nosidesway

Cm value in local y & zaxes

DFF None(Mandatory fordeflection check)

"Deflection Length" /Maxm. allowable localdeflection

DJ1 Start Jointof member

Joint No. denotingstarting point forcalculation of "DeflectionLength" (See Note 1)

DJ2 End Joint ofmember

Joint No. denoting endpoint for calculation of"Deflection Length" (SeeNote 1)

DMAX 100.0 cm. Maximum allowabledepth.

DMIN 0.0 cm. Minimum allowable depth.

FYLD 250 MPA

(36.25 KSI)

Yield strength of steel.

KY 1.0 K value in local y-axis.Usually, this is minor axis.

KZ 1.0 K value in local z-axis.Usually, this is major axis.

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ParameterName

Default Value Description

LY Member Length Length in local y-axis tocalculate slendernessratio.

LZ Member Length Same as above except inlocal z-axis (major).

MAIN 180 (Comp.Memb.)

Allowable Kl/r forslenderness calculationsfor compressionmembers.

NSF 1.0 Net section factor fortension members.

PROFILE - Used to search for thelightest section for theprofile(s) specified formember selection. SeeSection 5.48.1 of theTechnical ReferenceManual for details. 

RATIO 1.0 Permissible ratio of theactual to allowablestresses.

SSY 0.0 0.0 =    Sidesway in localy-axis.

1.0 =    No sidesway

SSZ 0.0 Same as above except inlocal z-axis.

TMAIN 400 (TensionMemb)

Allowable Kl/r forslenderness calculationsfor tension members.

TRACK 0.0 0.0 =    Suppress criticalmember stresses

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ParameterName

Default Value Description

1.0 =    Print all criticalmember stresses

2.0 =    Print expandedoutput. If there isdeflection check it will alsoprint the governing loadcase number for deflectioncheck whenever criticalcondition for design is notDEFLECTION.(see fig.8B.1)

UNF 1.0 Same as above providedas a fraction of actualmember length.

UNL Member Length Unsupported length forcalculating allowablebending stress.

Notes

a. "Deflection Length" is defined as the length that is used for calculation oflocal deflections within a member.  It may be noted that for most cases the"Deflection Length" will be equal to the length of the member. However, insome situations, the "Deflection Length" may be different. A straight linejoining DJ1 and DJ2 is used as the reference line from which localdeflections are measured.

For example, refer to the figure below where a beam has been modeledusing four joints and three members. The “Deflection Length” for all threemembers will be equal to the total length of the beam in this case. Theparameters DJ1 and DJ2 should be used to model this situation. Thus, for allthree members here, DJ1 should be 1 and DJ2 should be 4.

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D = Maximum local deflection for members 1, 2, and 3.

PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

b. If DJ1 and DJ2 are not used, "Deflection Length" will default to the memberlength and local deflections will be measured from original member line.

c. The above parameters may be used in conjunction with other available param-eters for steel design.

9B.5 Stability Requirements

Slenderness ratios are calculated for all members and checked against theappropriate maximum values. Section 3.7 of IS:800 summarizes the maximumslenderness ratios for different types of members. In STAAD implementation ofIS:800, appropriate maximum slenderness ratio can be provided for each member.If no maximum slenderness ratio is provided, compression members will bechecked against a maximum value of 180 and tension members will be checkedagainst a maximum value of 400.

9B.6 Truss Members

As mentioned earlier, a truss member is capable of carrying only axial forces. So indesign no time is wasted in calculating bending or shear stresses, thus reducingdesign time considerably. Therefore, if there is any truss member in an analysis

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(like bracing or strut, etc.), it is wise to declare it as a truss member rather than asa regular frame member with both ends pinned.

9B.7 Deflection Check

This facility allows the user to consider deflection as a criteria in the CODE CHECKand MEMBER SELECTION processes. The deflection check may be controlled usingthree parameters which are described in Table 9B.1. Note that deflection is used inaddition to other strength and stability related criteria. The local deflectioncalculation is based on the latest analysis results.

9B.8 Code Checking

The purpose of code checking is to verify whether the specified section is capableof satisfying applicable design code requirements. The code checking is based onthe IS:800 (1984) requirements. Forces and moments at specified sections of themembers are utilized for the code checking calculations. Sections may be specifiedusing the BEAM parameter or the SECTION command. If no sections are specified,the code checking is based on forces and moments at the member ends.

The code checking output labels the members as PASSed or FAILed. In addition,the critical condition (applicable IS:800 clause no.), governing load case, location(distance from the start) and magnitudes of the governing forces and moments arealso printed out.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

9B.9 Member Selection

STAAD is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section,that is, the lightest section, which satisfies the applicable code requirements. Thesection selected will be of the same type (I-Section, Channel etc.) as originallyspecified by the user. Member selection may be performed with all types of steelsections listed in Section 9B.12 and user provided tables. Selection of members,whose properties are originally provided from user specified table, will be limitedto sections in the user provided table. Member selection can not be performed onmembers whose cross sectional properties are specified as PRISMATIC.

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The process of MEMBER SELECTION may be controlled using the parameters listedin Table 9B.1. It may be noted that the parameters DMAX and DMIN may be used tospecify member depth constraints for selection. If PROFILE parameter is provided,the search for the lightest section is restricted to that profile. Up to three (3) profilesmay be provided for any member with a section being selected from each one.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

9B.10 Member Selection By Optimization

Steel section selection of the entire structure may be optimized. The optimizationmethod utilizes a state-of-the -art numerical technique which requires automaticmultiple analysis. The user may start without a specifically designated section.However, the section profile type (BEAM, COLUMN, CHANNEL, ANGLE etc.) mustbe specified using the ASSIGN command (see Chapter 6). The optimization is basedon member stiffness contributions and corresponding force distributions. Anoptimummember size is determined through successive analysis/design iterations.This method requires substantial computer time and hence should be used withcaution.

Refer to Section 5.48.4 of the Technical Reference Manual for additional details.

9B.11 Tabulated Results of Steel Design

For  code checking or member selection, the program produces the result in atabulated fashion. The items in the output table are explained as follows:

a. MEMBER refers to the member number for which the design is performed

b. TABLE refers to the INDIAN steel section name which has been checkedagainst the steel code or has been selected.

c. RESULT prints whether the member has PASSED or FAILed. If the RESULT isFAIL, there will be an asterisk (*) mark in front of the member number.

d. CRITICAL COND refers to the section of the IS:800 code which governs thedesign.

e. RATIO prints the ratio of the actual stresses to allowable stresses for the crit-ical condition. Normally a value of 1.0 or less will mean the member haspassed.

f. LOADING provides the load case number which governs the design.

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g. FX, MY and MZ provide the axial force, moment in local y-axis and moment inlocal z-axis respectively. Although STAAD does consider all the memberforces and moments (except torsion) to perform design, only FX,MY and MZare printed since they are the ones which are of interest, in most cases.

h. LOCATION specifies the actual distance from the start of the member to thesection where design forces govern.

i. If the parameter TRACK is set to 1.0, the program will block out part of thetable and will print allowable bending stresses in compression (FCY & FCZ)and tension (FTY & FTZ), allowable axial stress in compression (FA), andallowable shear stress (FV). When the parameter TRACK is set to 2.0 for allmembers parameter code values are as shown in the following example.

STAAD.PRO CODE CHECKING - ( IS-800)v1.0

********************************************

|--------------------------------------------------------------------------|| Y PROP-

ERTIES ||************* | IN CMUNIT || * |=============================| ===|=== ------

------ ||MEMBER 7 * | INDIAN SECTIONS | | AX =

85.0 || * | ST ISWB400 | | --Z AY =

34.4 ||DESIGN CODE * | | | AZ =

34.7 || IS-800 * =============================== ===|=== SY =

138.8 || * SZ =

1171.3 || * |<---LENGTH (ME= 3.00 --->| RY =4.0 ||************* RZ =

16.6 ||

|| 112.1( KN-METR)

||PARAMETER |L1

STRESSES ||IN NEWT MM | IN

NEWT MM||--------------- + ------

-------|| KL/R-Y= 74.2 | FA =

150.0 |

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| KL/R-Z= 18.1 + fa =1.0 || UNL = 3000.0 | FCZ =

139.9 || C = 400.0 + FTZ =

165.0 || CMY = 0.60 | FCY =

165.0 || CMZ = 0.40 + FTY =

165.0 || FYLD = 249.9 | L3 fbz =

95.7 || NSF = 0.9 +---+---+---+---+---+---+---+---+---+---| fby =0.0 || DFF = 0.0 90.5 FV =

100.0 || dff = 0.0 ABSOLUTE MZ ENVELOPE fv =

17.1 || (WITH LOAD NO.)

||

|| MAX FORCE/ MOMENT SUMMARY ( KN-METR)

|| -------------------------

||

|| AXIAL SHEAR-Y SHEAR-Z MOMENT-Y MOMENT-

Z ||

|| VALUE -23.9 60.6 0.0 0.0 112.1

|| LOCATION 0.0 3.0 0.0 0.0 0.0

|| LOADING 3 1 0 0 1

||

|

|**************************************************************************||**|

|* DESIGN SUMMARY ( KN-METR)*|

|* --------------*|

|**|

|* RESULT/ CRITICAL COND/ RATIO/ LOADING/*|

| FX MY MZ LOCATION|

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| ======================================================|

| PASS 7.1.2 BEND C 0.684 1|

| 7.39 T 0.0 -112.1 0.00|

|**|

|**************************************************************************|

9B.12 Indian Steel Table

This is an important feature of the program since the program will read sectionproperties of a steel member directly from the latest ISI steel tables (as publishedin ISI-800). These properties are stored in memory corresponding to the sectiondesignation (e.g., ISMB250, etc.). If called for, the properties are also used formember design. Since the shear areas are built in to these tables, sheardeformation is always considered for these members.

Almost all ISI steel tables are available for input. A complete listing of the sectionsavailable in the built-in steel section library may be obtained using the tools of thegraphical user interface.

Following are the descriptions of all the types of sections available:

Rolled Steel Beams (ISJB, ISLB, ISMB and ISHB)

All rolled steel beam sections are available the way they are designated in the ISIhandbook (e.g., ISJB225, ISWB400, etc.)

20 TO 30 TA ST ISLB325

Note: In case of two identical beams, the heavier beam is designated with an‘A” on the end (e.g., ISHB400 A, etc.).

1 TO 5 TA ST ISHB400A

Rolled Steel Channels (ISJC, ISLC and ISMC) 

All these shapes are available as listed in ISI section handbook. Designation of thechannels are per the scheme used by ISI.

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10 TO 20 BY 2 TA ST ISMC125

12 TA ST ISLC300

Double Channels

Back to back double channels, with or without spacing between them, are available.The letter D in front of the section name will specify a double channel (e.g., DISJC125, D ISMC75, etc.).

21 22 24 TA D ISLC225

Rolled Steel Angles

Both rolled steel equal angles and unequal angles are available for use in theSTAAD implementation of ISI steel tables. The following example with explanationswill be helpful in understanding the input procedure:

At present there is no standard way to define the local y and z axes for an anglesection. The standard section has local axis system as illustrated in Fig.2.4 of thismanual. The standard angle is specified as:

51 52 53 TA ST ISA60X60X6

This specification has the local z-axis (i.e., the minor axis corresponding to the V-Vaxis specified in the steel tables. Many engineers are familiar with a conventionused by some other programs in which the local y-axis is the minor axis. STAADprovides for this convention by accepting the command:

54 55 56 TA RA ISA50X30X6

Hint: RA denotes reverse angle

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Double Angles

Short leg back-to-back or long leg back-to-back double angles can be specified byinputting the word SD or LD, respectively, in front of the angle size. In case of anequal angle either LD or SD will serve the purpose. For example,

14 TO 20 TA LD ISA50X30X5 SP 1.5

23 27 TA SD ISA75X50X6

Rolled Tees (ISHT, ISST, ISLT and ISJT)

All the rolled tee sections are available for input as they are specified in the ISIhandbook. The following example illustrates the designated method.

1 2 5 8 TA ST ISNT100

67 68 TA ST ISST250

Pipes (Circular Hollow Sections)

To designate circular hollow sections from ISI tables, use PIP followed by thenumerical value of diameter and thickness of the section in mm omitting thedecimal section of the value provided for diameter. The following example willillustrate the designation.

10 15 TA ST PIP 213.2

specifies a 213 mm dia. pipe with 3.2 mm wall thickness

Circular pipe sections can also be specified by providing the outside and insidediameters of the section. For example,

1 TO 9 TA ST PIPE OD 25.0ID 20.0

specifies a pipe with outside dia. of 25 and inside dia. of 20 in current length units

Only code checking and no member selection will be performed if this type ofspecification is used.

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Tubes (Rectangular or Square Hollow Sections)

Designation of tubes from the ISI steel table is illustrated below.

For example,

15 TO 25 TA ST TUB 160808

Tubes, like pipes, can also be input by their dimensions (Height, Width andThickness) and not by any table designations.

6 TA ST TUBEDT 8.0WT 6.0 TH 0.5

is a tube that has a height of 8, a width of 6, and a wall thickness of 0.5.

Note: Only code checking and no member selection is performed for TUBEsections specified this way.

Plate And Angle Girders (With Flange Plates)

All plate and angle grinders (with flange plates) are available as listed in ISI sectionhandbook. The following example with explanations will be helpful inunderstanding the input procedure.

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A. Plate and angle girder symbol.

B. Web plate width in mm.

C. Web plate thickness in mm.

D. Flange angle, A X B X t, all in mm.

Symbol Angle

A 150X150X18

B 200X100X15

C 200X150X18

E 200X200X18

Table 9B.2 - Flange angle key

E. Flange plate width in mm.

F. Flange plate thickness in mm.

Single Joist with Channels and Plates on the Flanges to be Used asGirders

All single joist with channel and plates on the flanges to be used as girders areavailable as listed in ISI section handbook. The following example withexplanations will be helpful in understanding the input procedure.

A. Joist Designation

IW450 = ISWB450

B. Top flange channel designation:

350 = ISMC350

C. Constant (always X).

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D. Top flange plate thickness in mm.

Note: D = 0 for no plate.

E. Bottom flange plate thickness in mm.

Note: The heavier ISWB600 has been omitted, since the lighter ISWB600 ismore efficient.

9B.13 Column With Lacings And Battens

For columns with large loads it is desirable to build rolled sections at a distance andinter-connect them. The joining of element sections is done by two ways:

a. Lacing

b. Batten 

Double channel sections (back-to-back and face-to-face) can be joined either bylacing or by batten plates having riveted or welded connection.

Table 9B.3 gives the parameters that are required for Lacing or batten design.These parameters will have to be provided in unit NEW MMS along with parametersdefined in Table 9B.1.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CTYPE 1 Type of joining

1. implies single lacing with riv-eted connection

2. implies double lacing with riv-eted connection

Table 9B.3 - Parameters used in Indian Lacing or Batten steelmember design.

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ParameterName

DefaultValue

Description

3. implies single lacing withwelded connection

4. implies double lacing withwelded connection

5. implies batten with rivetedconnection

6. implies batten with weldedconnection

COG 0.0 mm Center of gravity of the channel.This parameter is used whenmember properties are definedthrough user provided table usingGENERAL option.

DBL 20 mm Nominal diameter of rivet

DCFR 0.0 Used when member properties aredefined through user providedtable using GENERAL option.

0. double channel back-to-back.

1. double channel face-to-face.

EDIST 32 mm(RivettedConnection)

25 mm(Welded

Connection)

Edge Distance.

FVB 100 N/mm2 Allowable shear stress in rivet

FYB 300 N/mm2 Allowable bearing stress in rivet

SPA 0.0 mm Spacing between double channels.This parameter is used whenmember properties are definedthrough user provided table using

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ParameterName

DefaultValue

Description

GENERAL option.

THETA 50 degree Angle of inclination of lacing bars.It should lie between 40 degreeand 70 degree.

WMIN 6 mm Minimum thickness of weld

WSTR 108 N/mm2 Allowable welding stress

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Indian Codes - Steel Design per IS802Indian Codes - Steel Design per IS802

9C.1 General CommentsThis section presents some general statements regarding the implementation ofIndian Standard code of practice (IS:802-1995 – Part 1) for structural steel designfor overhead transmission line towers in STAAD. The design philosophy andprocedural logistics for member selection and code checking are based upon theprinciples of allowable stress design. Two major failure modes are recognized:failure by overstressing, and failure by stability considerations. The flowingsections describe the salient features of the allowable stresses being calculated andthe stability criteria being used. Members are proportioned to resist the designloads without exceeding the allowable stresses and the most economic section isselected on the basis of least weight criteria. The code checking part of the programchecks stability and strength requirements and reports the critical loading conditionand the governing code criteria.

9C.2 Allowable Stresses

The member design  and code checking in STAAD are based upon the allowablestress design method as per IS:802 (1995). It is a method for proportioningstructural members using design loads and forces, allowable stresses, and designlimitations for the appropriate material under service conditions.

This section discusses the salient features of the allowable stresses specified byIS:802 and implemented in STAAD.

9C.2.1 Axial  Stress

Tensile Stress

The allowable tensile stress, as calculated in STAAD as per IS:802 is describedbelow.

The estimated tensile stresses on the net effective sectional area in variousmembers, multiplied by the appropriate factor of safety shall not exceed minimumguaranteed yield stress of the material.

International Design Codes Manual — 569

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Thus, the permissible stress in axial tension, σatin MPa on the net effective area of

the sections shall not exceed

σat= F

y

Where:

Fy= minimum yield stress of steel in Mpa

Compressive Stress

The estimated compressive stresses in various members multiplied by theappropriate factor of safety shall not exceed the value given by the formulaedescribed below.

I. Condition: when (b/t) ≤ [ (b/t)lim

= 210/√Fy]:

i. When KL/r ≤ Cc, the allowable compressive stress is (in N/mm2)

Fa= F

y{1 - 0.5[(KL/r)/C

c]2}

ii. When KL/r > Cc, the allowable compressive stress is (in N/mm2)

Fa= π2E/(KL/r)2

II. Condition: when (b/t)lim

< (b/t) ≤ 378/√Fy:

The equations in condition 1 shall be used, substituting for Fythe value F

crgiven by:

Fcr= F

y[1.677 - 0.677·(b/t)/(b/t)

lim]

III. Condition: when (b/t) > 378/√Fy

The equations in condition 1 shall be used, substituting for Fythe value F

crgiven by:

Fcr= 65,550/(b/t)

Where:

Fa= allowable unit stress in compression, Mpa

Fy= minimum guaranteed yield stress of the material, Mpa

K  = restraint factor,

L = unbraced length of the compression member in cm, and

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R = appropriate radius of gyration in cm.

E  = modulus of elasticity of steel in N/mm2

KL/r = largest effective slenderness ratio of any unbraced segment ofthe member,

b = distance from edge of the fillet to the extreme fibre in mm, and

t = thickness of flange in mm.

Note: The maximum permissible value of b/t for any type of steel shall notexceed 25.

9C.3 Stability Requirements

Slenderness ratios are calculated for all members and checked against theappropriate maximum values. Following are the default values used in STAAD:

Compression Member

Type of Member SlendernessLimit

Leg Members, ground wire peakmember and lower members ofcross arms in compression

120

Other members carryingcomputed stress

200

Redundant members and thosecarrying nominal stresses

250

Table 9C.1 - Slenderness ratio limits of com-pression members

Slenderness ratios of compression members are determined as follows:

International Design Codes Manual — 571

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ELAValue

Type of Member Calculationof KL/r

1 Leg sections or joint members bolted atconnections in both faces

L/r

2 Members with concentric loading at bothends of the unsupported panel with valuesof L/r up to and including 120

L/r

3 Member with concentric loading at oneend and normal eccentricities at the otherend of the unsupported panel for value ofL/r up to and including 120

30 +0.75L/r

4 Members with normal framingeccentricities at both ends of theunsupported panel for values of L/r up toand including 120

60 + 0.5L/r

5 Member unrestrained against rotation atboth ends of the unsupported panel forvalue of L/r from 120 to 200

L/r

6 Members partially restrained againstrotation at one end of the unsupportedpanel for values of L/r over 120 and up toand including 225

28.6 +0.762L/r

7 Members partially restrained againstrotation at both ends of the unsupportedpanel for values of L/r over 120 and up toand including 250

46.2 +0.615L/r

Table 9C.2 - Compression slenderness ratio calculation dependingon ELA parameter

If the value for ELA is given in the input for any particular member is such thatcondition for L/r ratio to fall within the specified range is not satisfied, STAAD goeson by the usual way of finding slenderness ratio using KL/r formula.

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Tension Members

Slenderness ratio KL/r of a member carrying axial tension only, shall not exceed400.

9C.4 Minimum Thickness Requirement

As per Clause7.1 of IS: 802-1995 minimum thickness of different tower membersshall be as follows:

Members Minimum Thickness(mm)

Galvanized Painted

Leg Members, ground wire peak member andlower members of cross arms in compression

5 6

Other members 4 5

9C.5 Code Checking

The purpose of code checking is to verify whether the specified section is capable ofsatisfying applicable design code requirements. The code checking is based on theIS:802 (1995) requirements. Axial forces at two ends of the members are utilizedfor the code checking calculations.

The code checking output labels the members as PASSed or FAILed. In addition,the critical condition, governing load case, location (distance from the start) andmagnitudes of the governing forces are also printed out. Using TRACK 9 optioncalculation steps are also printed.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

9C.5.1 Design Steps

The following are the steps used by the program in member design:

International Design Codes Manual — 573

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1. Thickness of the member (maximum of web and flange thicknesses) ischecked against minimum allowable thickness, depending upon whether themember is painted or galvanised.

2. If the minimum thickness criterion is fulfilled, the program determineswhether the member is under compression or tension for the loadcase underconsideration. Depending upon whether the member is under tension orcompression the slenderness ratio of the member is calculated. This cal-culated ratio is checked against allowable slenderness ratio.

3. If the slenderness criterion is fulfilled check against allowable stress is per-formed. Allowable axial and tensile stresses are calculated. If the member isunder tension and there is no user defined net section factor (NSF), the netsection factor is calculated by the program itself (Refer Section 8C.10).Actual axial stress in the member is calculated. The ratio for actual stress toallowable stress, if less than 1.0 or user defined value, the member haspassed the check.

4. Number of bolts required for the critical loadcase is calculated.

9C.6 Member Selection

STAAD is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section,that is, the lightest section, which satisfies the applicable code requirements. Thesection selected will be of the same type (either angle or channel) as originallyspecified by the user. Member selection may be performed with all angle orchannel sections and user provided tables. Selection of members, whoseproperties are originally provided from user specified table, will be limited tosections in the user provided table.

The process of MEMBER SELECTION may be controlled using the parameters listedin Table 9C.3. It may be noted that the parameters DMAX and DMIN may be used tospecify member depth constraints for selection. If PROFILE parameter is provided,the search for the lightest section is restricted to that profile. Up to three (3)profiles may be provided for any member with a section being selected from eachone.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

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9C.7 Member Selection by Optimization

Steel section selection of the entire structure may be optimized. The optimizationmethod utilizes a state-of-the -art numerical technique which requires automaticmultiple analysis. The optimization is based on member stiffness contributions andcorresponding force distributions.

An optimummember size is determined through successive analysis/designiterations. This method requires substantial computer time and hence should beused with caution.

Refer to Section 5.48.4 of the Technical Reference Manual for additional details.

9C.8 Tabulated Results of Steel  Design

An example of a TRACK 2.0 output for a compression member is shown here:

STAAD.PRO CODE CHECKING - ( IS-802)v1.0

********************************************|--------------------------------------------------------------------

------|| Y PROP-

ERTIES ||************* | IN CM

UNIT || * |=============================| ==| |== -------

----- ||MEMBER 8 * | INDIAN SECTIONS | | | AX =

17.0 || * | ST ISA125x95x8 | | | --Z AY =

6.7 ||DESIGN CODE * | | | | AZ =

5.1 || IS-802 * =============================== ==| |== SY =

38.8 || * SZ =

16.6 || * |<---LENGTH (ME= 1.80 --->| RY =

4.4 ||************* RZ =

2.0 ||

||

||PARAMETER BOLTING

STRESSES ||IN NEWT MM IN

NEWT MM|

International Design Codes Manual — 575

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|--------------- ------------- -------------|| L/R-Y = 40.5 BOLT DIA = 12 MM FA =

188.4 || L/R-Z = 87.9 BOLT CAP = 24.66 KN fa =80.7 || KL/R = 87.9 # BOLT = 6 FYB =

436.0 || FYLD = 250.0 FVB =

218.0 || GALVA = 0.0

|| C = 1.0

|| LEG = 1.0

|| ELA = 1.0

|| NSF = 1.0

||

|

|**************************************************************************||*

*||* DESIGN SUMMARY ( KN-METR)

*||* --------------

*||*

*||* RESULT/ CRITICAL COND/ RATIO/ LOADING/

*|| FX MY MZ LOCATION

|| ======================================================

|| PASS COMPRESSION 0.428 1

|| 137.13 C 0.0 0.0 0.00

||*

*|

|**************************************************************************||

||-------------------------------------------------------------------

-------|

Using TRACK 9.0 also adds the following set of calculation details:

DETAILS OF CALCULATION

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----------------------

CHECK FOR MINIMUM THICKNESS---------------------------

TYPE : PAINTED

MIN. ALLOWABLE THICKNESS : 6.0 MM

ACTUAL THICKNESS : 8.0 MM

RESULT : PASS

CHECK FOR SLENDERNESS RATIO---------------------------

VALUE OF L/r : 87.94

EQN. USED TO FIND KL/r : L/r

ACTUAL VALUE OF KL/r : 87.94

ALLOWABLE KL/r : 120.00

RESULT : PASS

CALCULATION OF ALLOWABLE STRESS---------------------------------

CRITICAL CONDITION : COMPRESSION

Cc : sqrt(2*3.14159265*3.14159265*E : 127.53

b : LENGTH OF LEG - WEB THICKNESS - ROOT RADIUS: 125.0 - 8.0 - 9.0 : 108.0 MM

(b/t)lim : 210/sqrt(fy) : 13.28

(b/t)cal : 13.50

(b/t)cal > (b/t)lim

(b/t)lim (modified) : 378/sqrt(fy) : 23.91

(b/t)cal <= (b/t)lim (modified) AND KL/r <= Cc

Fcr : (1.677 - (0.677*(b/t)cal/(b/t)lim))*fy : 247.18 MPA

ALLOWABLE AXIAL COMP. STRESS : (1-0.5*(KL/r/Cc)*(KL/r/Cc))*Fcr :188.41 MPA

CHECK AGAINST PERMISSIBLE STRESS--------------------------------

LOAD NO. : 1

DESIGN AXIAL FORCE : 137131.16 N

ACTUAL AXIAL COMP. STRESS : 137131.16 / 1700.0 : 80.67 MPA

RESULT : PASSEXAMPLE PROBLEM NO.1 -- PAGE

NO. 24

BOLTING-------

BOLT DIA : 12 MM

SHEARING CAP : 24.66 KN

BEARING CAP : 41.86 KN

BOLT CAP : 24.66 KN

NO. OF BOLTS REQD. : 6

************** END OF TABULATED RESULT OF DESIGN **************

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9C.9 Design Parameters

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CNSF 0.0 This parameter indicates whetheruser has defined the net sectionfactor or the program will calculateit.

0. Use specified NSF value

1. Net section factor will be cal-culated.

DANGLE 0.0 This parameter indicates how thepair of angles are connected toeach other. This is required to findwhether the angle is in single ordouble shear and the net sectionfactor.

0. Double angle placed back-to-back and connected to eachside of a gusset plate

1. Pair of angle placed back-to-back connected by only oneleg of each angle to the sameside of a gusset plate

DBL 12 mm Diameter of bolt for calculation ofnumber of bolts and net sectionfactor.

DMAX 100.0 cm. Maximum allowable depth.

DMIN 0.0 cm. Minimum allowable depth.

ELA 1.0 This parameter indicates what type

Table 9C.3 - Indian Steel Design IS 802 Parameters

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Indian Codes - Steel Design per IS802

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ParameterName

DefaultValue

Description

of end conditions is to be used.Refer Section 9C.3.

FVB 218 MPA Allowable shear stress in bolt

FYB 436 MPA Allowable bearing stress in bolt

FYLD 250 MPA Yield Strength of steel

GUSSET 5 mm Thickness of gusset plate.

Minimum of the thicknesses of thegusset plate and the leg is used forcalculation of the capacity of bolt inbearing

KY 1.0 K value in local y-axis. Usually, thisis minor axis.

KZ 1.0 K value in local z-axis. Usually, thisis major axis.

LEG 1.0 This parameter is meant for plainangles.

0. The angle is connected byshorter leg

1. The angle is connected bylonger leg

LY MemberLength

Unbraced length in local z-axis tocalculate slenderness ratio.

LZ MemberLength

Unbraced length in local z-axis tocalculate slenderness ratio.

MAIN 1.0 Type of member to find allowableKl/r for slenderness calculations formembers.

1. Leg, Ground wire peak andlower members of cross arms

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ParameterName

DefaultValue

Description

in compression (KL/r = 120)

2. Members carrying computedstress (KL/r =  200)

3. Redundant members andmembers carrying nominalstresses (KL/r = 250)

4. Tension members (KL/r =400)

10. Do not perform KL/r check

Any value greater than 10.0indicates user defined allowableKL/r ratio. For this case KY and KZvalues are must to find actual KL/rratio of the member.

NSF 1.0 Net section factor for tensionmembers

NHL 0.0 mm Deduction for holes.

Default value is one bolt width plus1.5 mm.  If the area of holes cut byany straight, diagonal or zigzagline across the member is differentfrom the default value, thisparameter is to be defined.

TRACK 0.0 Level of output detail:

0. Suppress critical memberstresses

1. Print all critical memberstresses

2. Print expanded output.

9. Print design calculationsalong with expanded output

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ParameterName

DefaultValue

Description

(not available in GUI input).

9C.10 Calculation of Net Section Factor

The procedure for calculating the net section factor for an angle section is asfollows:

l For a channel section, net section factor is taken to be 1.0.

l For an angle section, it is the ratio of the net effective area, Anet, to the gross

area, where:

a. Single angle connected by only one leg

Anet

= A1+ A

2· K

1

Where:

A1= net cross-sectional area of the connected leg

A2= gross cross-sectional area of the unconnected leg

K1= 3·A

1/(3·A

1+ A

2)

The area of a leg of an angle = Thickness of angle x (length of leg –0.5x thickness of leg)

b. Pair of angles placed back-to-back connected by only one leg of eachangle to the same side of a gusset plate

Anet

= A1+ A

2· K

1

Where:

A1= net cross-sectional area of the connected leg

A2= gross cross-sectional area of the unconnected leg

K1= 5·A

1/(5·A

1+ A

2)

The area of a leg of an angle = Thickness of angle x (length of leg –0.5x thickness of leg)

International Design Codes Manual — 581

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c. Double angles placed back-to-back and connected to each side of agusset plate

Anet= gross area minus the deduction for holes

9C.11 Example Problem No. 28

A transmission line tower is subjected to different loading conditions. Design somemembers as per IS-802 and show detailed calculation steps for the critical loadingcondition.

Given

End Condition = Members with normal framing eccentricities at both ends of theunsupported panel for values of L/r up to and including 120

Diameter of the bolt = 16 mm

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Thickness of the gusset plate = 8 mm

Net Section Factor is to be calculated.

STAAD Input File

This input file is included with the program asC:\SPROV8I\STAAD\EXAMP\IND\EXAMP28.STD.

STAAD TRUSS

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 3 0 3; 2 1.2 27 1.2; 3 2.8 3 2.8; 4 2.6 6 2.6; 5 2.4 9 2.4;

6 2.2 12 2.2; 7 2 15 2; 8 1.8 18 1.8; 9 1.6 21 1.6; 10 1.4 24 1.4;

11 -3 0 3; 12 -1.2 27 1.2; 13 -2.8 3 2.8; 14 -2.6 6 2.6; 15 -2.4 9 2.4;

16 -2.2 12 2.2; 17 -2 15 2; 18 -1.8 18 1.8; 19 -1.6 21 1.6; 20 -1.4 241.4;

21 3 0 -3; 22 1.2 27 -1.2; 23 2.8 3 -2.8; 24 2.6 6 -2.6; 25 2.4 9 -2.4;

26 2.2 12 -2.2; 27 2 15 -2; 28 1.8 18 -1.8; 29 1.6 21 -1.6; 30 1.4 24 -1.4;

31 -3 0 -3; 32 -1.2 27 -1.2; 33 -2.8 3 -2.8; 34 -2.6 6 -2.6; 35 -2.4 9 -2.4;

36 -2.2 12 -2.2; 37 -2 15 -2; 38 -1.8 18 -1.8; 39 -1.6 21 -1.6;

40 -1.4 24 -1.4; 41 1.2 30 1.2; 42 -1.2 30 1.2; 43 1.2 30 -1.2;

44 -1.2 30 -1.2; 45 4.2 27 1.2; 46 7.2 27 1.2; 47 4.2 30 1.2; 48 4.2 27-1.2;

49 7.2 27 -1.2; 50 4.2 30 -1.2; 51 -4.2 27 1.2; 52 -7.2 27 1.2;

53 -4.2 30 1.2; 54 -4.2 27 -1.2; 55 -7.2 27 -1.2; 56 -4.2 30 -1.2;

57 1.2 33 1.2; 58 -1.2 33 1.2; 59 1.2 33 -1.2; 60 -1.2 33 -1.2; 61 0 350;

MEMBER INCIDENCES

1 1 3; 2 3 4; 3 4 5; 4 5 6; 5 6 7; 6 7 8; 7 8 9; 8 9 10; 9 10 2; 10 11 13;

International Design Codes Manual — 583

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11 13 14; 12 14 15; 13 15 16; 14 16 17; 15 17 18; 16 18 19; 17 1920; 18 20 12;

19 13 3; 20 14 4; 21 15 5; 22 16 6; 23 17 7; 24 18 8; 25 19 9; 26 2010;

27 12 2; 28 11 3; 29 1 13; 30 13 4; 31 3 14; 32 14 5; 33 15 4; 34 156;

35 16 5; 36 16 7; 37 17 6; 38 17 8; 39 18 7; 40 18 9; 41 19 8; 42 1910;

43 20 9; 44 20 2; 45 12 10; 46 21 23; 47 23 24; 48 24 25; 49 25 26;50 26 27;

51 27 28; 52 28 29; 53 29 30; 54 30 22; 55 3 23; 56 4 24; 57 5 25;58 6 26;

59 7 27; 60 8 28; 61 9 29; 62 10 30; 63 2 22; 64 1 23; 65 21 3; 66 324;

67 23 4; 68 4 25; 69 5 24; 70 5 26; 71 6 25; 72 6 27; 73 7 26; 74 728;

75 8 27; 76 8 29; 77 9 28; 78 9 30; 79 10 29; 80 10 22; 81 2 30; 8231 33;

83 33 34; 84 34 35; 85 35 36; 86 36 37; 87 37 38; 88 38 39; 89 3940; 90 40 32;

91 23 33; 92 24 34; 93 25 35; 94 26 36; 95 27 37; 96 28 38; 97 2939; 98 30 40;

99 22 32; 100 21 33; 101 31 23; 102 23 34; 103 33 24; 104 24 35;105 25 34;

106 25 36; 107 26 35; 108 26 37; 109 27 36; 110 27 38; 111 28 37;112 28 39;

113 29 38; 114 29 40; 115 30 39; 116 30 32; 117 22 40; 118 33 13;119 34 14;

120 35 15; 121 36 16; 122 37 17; 123 38 18; 124 39 19; 125 40 20;126 32 12;

127 31 13; 128 11 33; 129 33 14; 130 13 34; 131 34 15; 132 35 14;133 35 16;

134 36 15; 135 36 17; 136 37 16; 137 37 18; 138 38 17; 139 38 19;140 39 18;

141 39 20; 142 40 19; 143 40 12; 144 32 20; 145 32 44; 146 12 42;147 2 41;

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148 22 43; 149 42 41; 150 41 43; 151 43 44; 152 44 42; 153 12 41;154 42 2;

155 22 41; 156 43 2; 157 43 32; 158 44 22; 159 12 44; 160 32 42;161 41 47;

162 47 45; 163 45 2; 164 47 46; 165 46 45; 166 41 45; 167 43 50;168 50 48;

169 48 22; 170 50 49; 171 49 48; 172 43 48; 173 47 50; 174 46 49;175 45 48;

176 41 50; 177 50 46; 178 43 47; 179 47 49; 180 22 50; 181 2 47;182 22 45;

183 2 48; 184 47 48; 185 50 45; 186 45 49; 187 48 46; 188 42 53;189 53 51;

190 51 12; 191 53 52; 192 52 51; 193 42 51; 194 44 56; 195 56 54;196 54 32;

197 56 55; 198 55 54; 199 44 54; 200 53 56; 201 52 55; 202 51 54;203 42 56;

204 56 52; 205 44 53; 206 53 55; 207 32 56; 208 12 53; 209 32 51;210 12 54;

211 53 54; 212 56 51; 213 51 55; 214 54 52; 215 44 60; 216 42 58;217 41 57;

218 43 59; 219 60 59; 220 59 57; 221 57 58; 222 58 60; 223 44 58;224 42 60;

225 42 57; 226 41 58; 227 44 59; 228 43 60; 229 43 57; 230 41 59;231 60 57;

232 59 58; 235 33 3; 236 13 23; 237 34 4; 238 14 24; 239 35 5; 24015 25;

241 36 6; 242 16 26; 243 37 7; 244 17 27; 245 38 8; 246 18 28; 24739 9;

248 19 29; 249 40 10; 250 20 30; 251 32 2; 252 22 12; 253 44 41;254 43 42;

255 60 61; 256 58 61; 257 57 61; 258 59 61;

MEMBER PROPERTY INDIAN

1 TO 18 46 TO 54 82 TO 90 145 TO 148 215 TO 218 TA LDISA200X150X18 SP 0.01

19 TO 26 28 TO 45 55 TO 62 64 TO 81 91 TO 98 100 TO 125 127 TO144 155 156 -

159 160 223 224 229 230 235 TO 250 TA ST ISA150X150X10

International Design Codes Manual — 585

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27 63 99 126 149 TO 154 157 158 161 TO 214 219 TO 222 225 TO228 231 232 251 -

252 TO 258 TA ST ISA80X50X6

CONSTANTS

E 2.05E+008 ALL

POISSON 0.3 ALL

DENSITY 76.8195 ALL

ALPHA 6.5E-006 ALL

SUPPORTS

1 11 21 31 FIXED

UNIT METER KG

LOAD 1 VERT

SELFWEIGHT Y -1

JOINT LOAD

61 FX 732

46 49 52 55 FX 153

61 FX 1280 FY -1016 FZ 160

46 49 52 55 FX 9006 FY -7844 FZ 1968

2 12 22 32 FX 4503 FY -3937 FZ 1968

LOAD 2 GWBC

SELFWEIGHT Y -1

JOINT LOAD

61 FX 549

46 49 52 55 FX 1148

61 FX 515 FY -762 FZ 2342

46 49 52 55 FX 6755 FY -5906

2 12 22 32 FX 3378 FY -2953

LOAD 3 LEFT PCBC

SELFWEIGHT Y -1

JOINT LOAD

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61 FX 549

46 49 52 55 FX 1148

61 FX 960 FY -762

46 49 FX 6755 FY -5906

52 55 FX 4211 FY -4551 FZ 13293

2 12 22 32 FX 3378 FY -2953

LOAD 4 RIGHT PCBC

SELFWEIGHT Y -1

JOINT LOAD

61 FX 549

46 49 52 55 FX 1148

61 FX 960 FY -762

52 55 FX 6755 FY -5906

46 49 FX 4211 FY -4551 FZ 13293

2 12 22 32 FX 3378 FY -2953

PERFORMANALYSIS

UNIT NEWMMS

PARAMETER

CODE IS802

LY 2800 MEMB 28

LZ 2800 MEMB 28

MAIN 1.0 MEMB 1

ELA 4 MEMB 1

CNSF 1.0 MEMB 28

DBL 16 ALL

GUSSET 8 ALL

TRACK 9 ALL

CHECK CODEMEMB 1 28

FINISH

International Design Codes Manual — 587

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Output

A portion of the output for the TRACK 9.0 member code check follows:

STAAD.PRO CODE CHECKING - ( IS-802)v1.0

********************************************|-------------------------------------------------------------------

-------|| Y PROP-

ERTIES ||************* | IN CMUNIT || * |=============================| ==||== ------

------ ||MEMBER 1 * | INDIAN SECTIONS | || AX =

120.0 || * | LD ISA200X150X18 | || --Z AY =

48.0 ||DESIGN CODE * | | || AZ =

36.0 || IS-802 * |-----------------------------| || SY =

297.3 || * SZ =

350.6 || * |<---LENGTH (ME= 3.01 --->| RY =6.2 ||************* RZ =6.3 ||

||

||PARAMETER BOLTING

STRESSES ||IN NEWT MM IN

NEWT MM||--------------- ------------- ------

-------|| L/R-Y = 48.6 BOLT DIA = 16 MM FA =

195.1 || L/R-Z = 47.7 BOLT CAP = 55.81 KN fa =

145.2 || KL/R = 84.3 # BOLT = 32 FYB =

436.0 || FYLD = 250.0 FVB =

218.0 || GALVA = 0.0

|| C = 1.0

|

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| LEG = 1.0|

| ELA = 4.0|

| NSF = 1.0|

||

|**************************************************************************||**|

|* DESIGN SUMMARY ( KN-METR)*|

|* --------------*|

|**|

|* RESULT/ CRITICAL COND/ RATIO/ LOADING/*|

| FX MY MZ LOCATION|

| ======================================================|

| PASS COMPRESSION 0.744 1|

| 1742.26 C 0.0 0.0 0.00|

|**|

|**************************************************************************||

||--------------------------------------------------------------------

------|STAAD TRUSS -- PAGE

NO. 5DETAILS OF CALCULATION----------------------

CHECK FOR MINIMUM THICKNESS---------------------------

TYPE : PAINTED

MIN. ALLOWABLE THICKNESS : 6.0 MM

ACTUAL THICKNESS : 18.0 MM

RESULT : PASS

CHECK FOR SLENDERNESS RATIO---------------------------

VALUE OF L/r : 48.63

EQN. USED TO FIND KL/r : 60.0 + 0.5*L/r

ACTUAL VALUE OF KL/r : 84.31

ALLOWABLE KL/r : 120.00

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RESULT : PASS

CALCULATION OF ALLOWABLE STRESS---------------------------------

CRITICAL CONDITION : COMPRESSION

Cc : sqrt(2*3.14159265*3.14159265*E : 127.24

b : LENGTH OF LEG - WEB THICKNESS - ROOT RADIUS: 200.0 - 18.0 - 15.0 : 167.0 MM

(b/t)lim : 210/sqrt(fy) : 13.28

(b/t)cal : 9.28

(b/t)cal <= (b/t)lim AND KL/r <= Cc

ALLOWABLE AXIAL COMP. STRESS : (1-0.5*(KL/r/Cc)*(KL/r/Cc))*fy :195.07 MPA

CHECK AGAINST PERMISSIBLE STRESS--------------------------------

LOAD NO. : 1

DESIGN AXIAL FORCE : 1742259.75 N

ACTUAL AXIAL COMP. STRESS :1742259.75 / 12000.0 : 145.19 MPA

RESULT : PASSSTAAD TRUSS -- PAGE

NO. 6

BOLTING-------

BOLT DIA : 16 MM

SHEARING CAP : 87.66 KN

BEARING CAP : 55.81 KN

BOLT CAP : 55.81 KN

NO. OF BOLTS REQD. : 32STAAD TRUSS -- PAGE

NO. 7STAAD.PRO CODE CHECKING - ( IS-802)

v1.0********************************************

|--------------------------------------------------------------------------|| Y PROP-

ERTIES ||************* | IN CMUNIT || * |=============================| ==| |== ------

------ ||MEMBER 28 * | INDIAN SECTIONS | | | AX =

29.2 || * | ST ISA150X150X10 | | | --Z AY =

10.0 ||DESIGN CODE * | | | | AZ =

10.0 || IS-802 * =============================== ==| |== SY =

95.7 || * SZ =

44.8 |

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| * |<---LENGTH (ME= 6.53 --->| RY =5.9 ||************* RZ =

3.0 ||

||

||PARAMETER BOLTING

STRESSES ||IN NEWT MM IN

NEWT MM||--------------- ------------- -------

------|| L/R-Y = 47.5 BOLT DIA = 16 MM FA =

249.9 || L/R-Z = 94.0 BOLT CAP = 43.83 KN fa =

48.5 || KL/R = 94.0 # BOLT = 3 FYB =

436.0 || FYLD = 250.0 FVB =

218.0 || GALVA = 0.0

|| C = 1.0

|| LEG = 1.0

|| ELA = 1.0

|| NSF = 0.8

||

|

|**************************************************************************||**|

|* DESIGN SUMMARY ( KN-METR)*|

|* --------------*|

|**|

|* RESULT/ CRITICAL COND/ RATIO/ LOADING/*|

| FX MY MZ LOCATION|

| ======================================================|

| PASS TENSION 0.194 3|

| 112.86 T 0.0 0.0 6.53|

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|**|

|**************************************************************************||

||-------------------------------------------------------------------

-------|STAAD TRUSS -- PAGE

NO. 8DETAILS OF CALCULATION----------------------

CHECK FOR MINIMUM THICKNESS---------------------------

TYPE : PAINTED

MIN. ALLOWABLE THICKNESS : 6.0 MM

ACTUAL THICKNESS : 10.0 MM

RESULT : PASS

CHECK FOR SLENDERNESS RATIO---------------------------

VALUE OF L/r : 93.96

EQN. USED TO FIND KL/r : K*L/r

ACTUAL VALUE OF KL/r : 93.96

ALLOWABLE KL/r : 400.00

RESULT : PASS

CALCULATION OF ALLOWABLE STRESS---------------------------------

CRITICAL CONDITION : TENSION

ALLOWABLE AXIAL TENSILE STRESS : 249.94 MPA

CHECK AGAINST PERMISSIBLE STRESS--------------------------------

LOAD NO. : 3

DESIGN AXIAL FORCE : 112855.91 N

ACTUAL AXIAL TENSILE STRESS : 112855.91 / ( 2920.0*0.797 ) :48.51 MPA

RESULT : PASS

BOLTING-------

BOLT DIA : 16 MM

SHEARING CAP : 43.83 KN

BEARING CAP : 55.81 KN

BOLT CAP : 43.83 KN

NO. OF BOLTS REQD. : 3STAAD TRUSS -- PAGE

NO. 9

************** END OF TABULATED RESULT OF DESIGN **************

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Indian Codes - Design per Indian Cold FormedSteel Code

9D.1 General

Provisions of IS:801-1975, including revisions dated May, 1988, have beenimplemented. The program allows design of single (non-composite) members intension, compression, bending, shear, as well as their combinations. Cold work offorming strengthening effects has been included as an option.

9D.2 Cross-Sectional Properties

The user specifies the geometry of the cross-section by selecting one of the sectionshape designations from the Gross Section Property Tables from IS:811-1987(Specification for cold formed light gauge structural steel sections).

The Tables are currently available for the following shapes:

l Channel with Lips

l Channel without Lips

l Angle without Lips

l Z with Lips

l Hat

Shape selection may be done using the member property pages of the graphicaluser interface (GUI) or by specifying the section designation symbol in the inputfile.

The properties listed in the tables are gross section properties. STAAD.Pro usesunreduced section properties in the structure analysis stage. Both unreduced andeffective section properties are used in the design stage, as applicable.

9D.3 Design Procedure

The program calculates effective section properties in accordance with Clause5.2.1.1. Cross-sectional properties and overall slenderness of members arechecked for compliance with

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l Clause 6.6.3, Maximum Effective Slenderness Ratio for members inCompression

l Clause 5.2.3, Maximum Flat Width Ratios for Elements in Compression

l Clause 5.2.4, Maximum Section Depths.

The program will check member strength in accordance with Clause 6 of theStandard as follows:

Members in tension

Resistance is calculated in accordance with Clauses 6.1

Members in bending and shear

Resistance calculations are based on Clauses:

l Clause 6.4.1 Shear stress in webs,

l Clause 6.4.2 Bending stress in webs

l Clause 6.4.3 Combined Bending and Shear in Webs.

Members in compression

Resistance calculations are based on Clauses:

l Clause 6.2 Compression on flat unstiffened element,

l Clause 6.6.1.1 Shapes not subject to torsional-flexural buckling,

l Clause 6.6.1.2 Singly-symmetric sections and nonsymmetrical shapes ofopen cross section or intermittently fastened singly-symmetrical componentsof built-up shapes having Q = 1.0 which may be subject to torsional-flexuralbuckling,

l Clause 6.6.1.3 Singly-symmetric sections and nonsymmetrical shapes orintermittently fastened singly-symmetrical components of built-up shapeshaving Q < 1.0 which may be subject to torsional-flexural buckling,

l Clause 6.8 Cylindrical Tubular Sections.

Members in compression and bending

Resistance calculations are based on Clauses:

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l All clauses for members in compression

l Clause 6.3 Laterally Unsupported Members,

l Clause 6.7.1 Doubly-symmetric shapes or Shapes not subjected to torsionalor torsional-flexural buckling

l Clause 6.7.2. Singly-symmetric shapes or Intermittently fastened singly-sym-metric components of built-up shapes having Q=1.0 which may be subjectedto torsional-flexural buckling

l Clause 6.7.3. Singly-symmetric shapes or Intermittently fastened singly-sym-metric components of built-up shapes having Q<1.0 which may be subjectedto torsional-flexural buckling.

9D.4 Code Checking and Member Selection

The following two design modes are available:

Code Checking 

The program compares the resistance of members with the applied load effects, inaccordance with IS:801-1975. Code checking is carried out for locations specifiedby the user via the SECTION command or the BEAM parameter. The results arepresented in a form of a PASS/FAIL identifier and a RATIO of load effect toresistance for each member checked. The user may choose the degree of detail inthe output data by setting the TRACK parameter.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Member Selection 

The user may request that the program search the cold formed steel shapesdatabase (IS standard sections) for alternative members that pass the code checkand meet the least weight criterion. In addition, a minimum and/or maximumacceptable depth of the member may be specified. The program will then evaluateall database sections of the type initially specified (i.e., channel, angle, etc.) and, ifa suitable replacement is found, presents design results for that section. If nosection satisfying the depth restrictions or lighter than the initial one can be found,the program leaves the member unchanged, regardless of whether it passes thecode check or not.

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Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

9D.5 Design Parameters

Input for the coefficients of uniform bending must be specified.

The following table contains the input parameters for specifying values of designvariables and selection of design options.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as IS801

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM

1.0 When this parameter is set to

0. the 13 location check is notconducted, and instead,checking is done only at thelocations specified by theSECTION command (SeeSTAAD manual for details.For TRUSS members onlystart and end locations aredesigned.

1. the adequacy of the memberis determined by checking atotal of 13 equally spacedlocations along the length ofthe member.

Table 9D.1 - Indian cold formed steel design parameters

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ParameterName

DefaultValue

Description

CMY 0.85 Coefficient of equivalent uniformbending Ω

y. See IS:801-1975, 6.7.

Used for Combined axial load andbending design. Values range from0.4 to 1.0.

CMZ 1.0 Coefficient of equivalent uniformbending Ω

z. See IS:801-1975, 6.7.

Used for Combined axial load andbending design. Values range from0.4 to 1.0.

CWY 0.85 Specifies whether the cold work offorming strengthening effectshould be included in resistancecomputation. See IS:801-1975,6.1.1

0. effect should not be included

1. effect should be included

FLX 1 Specifies whether torsional-flexural buckling restraint isprovided or is not necessary forthe member. See IS:801-1975,6.6.1

0. Section not subject to tor-sional flexural buckling

1. Section subject to torsionalflexural buckling

FU 450 MPa

(4588.72

kg/cm2)

Ultimate tensile strength of steel incurrent units.

FYLD 353.04 MPa

(3600.0

Yield strength of steel in currentunits.

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ParameterName

DefaultValue

Description

kg/cm2)

KX 1.0 Effective length factor for torsionalbuckling. It is a fraction and isunit-less. Values can range from0.01 (for a column completelyprevented from buckling) to anyuser specified large value. It isused to compute the KL/R ratio fortwisting for determining thecapacity in axial compression.

KY 1.0 Effective length factor for overallbuckling about the local Y-axis. Itis a fraction and is unit-less. Valuescan range from 0.01 (for a columncompletely prevented frombuckling) to any user specifiedlarge value. It is used to computethe KL/R ratio for determining thecapacity in axial compression.

KZ 1.0 Effective length factor for overallbuckling in the local Z-axis. It is afraction and is unit-less. Values canrange from 0.01 (for a membercompletely prevented frombuckling) to any user specifiedlarge value. It is used to computethe KL/R ratio for determining thecapacity in axial compression.

LX Memberlength

Unbraced length for twisting. It isinput in the current units of length.Values can range from 0.01 (for amember completely preventedfrom torsional buckling) to anyuser specified large value. It isused to compute the KL/R ratio for

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ParameterName

DefaultValue

Description

twisting for determining thecapacity in axial compression.

LY Memberlength

Effective length for overallbuckling in the local Y-axis. It isinput in the current units of length.Values can range from 0.01 (for amember completely preventedfrom buckling) to any userspecified large value. It is used tocompute the KL/R ratio fordetermining the capacity in axialcompression.

LZ Memberlength

Effective length for overallbuckling in the local Z-axis. It isinput in the current units of length.Values can range from 0.01 (for amember completely preventedfrom buckling) to any userspecified large value. It is used tocompute the KL/R ratio fordetermining the capacity in axialcompression.

MAIN 0 0 – Check slenderness ratio

0 – Do not check slenderness ratio

NSF 1.0 Net section factor for tensionmembers

DMAX 2540.0

cm.

Maximum allowable depth, in thecurrent units.

RATIO 1.0 Permissible ratio of actual toallowable stresses

STIFF MemberLength

Spacing of shear stiffeners for stiff-ened flat webs, in current units.

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ParameterName

DefaultValue

Description

TRACK 0 This parameter is used to controlthe level of detail in which thedesign output is reported in theoutput file. The allowable valuesare:

0. Prints only the membernumber, section name, ratio,and PASS/FAIL status.

1. Prints the design summary inaddition to that printed byTRACK 0

2. Prints member and materialproperties in addition to thatprinted by TRACK 1.

TSA 1 Specifies whether webs of flexuralmembers are adequately stiffenedto satisfy the requirements ofIS:801-1975, 5.2.4.

0. Do not comply with 5.2.4

1. Comply with 5.2.4

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Section 10

Japanese Codes

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Japanese Codes - Concrete Design Per 1991 AIJ10A.1 Design Operations

STAAD has the capabilities of performing concrete design based on the AIJstandard for structural calculation of Reinforced Concrete Structures (1991edition). Design for a member involves calculation of the amount of reinforcementrequired for the member. Calculations are based on the user specified propertiesand the member forces obtained from the analysis. In addition, the detailsregarding placement of the reinforcement on the cross section are also reported inthe output.

10A.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be designed:

l For Beams — Prismatic (Rectangular and Square)

l For Columns — Prismatic (Rectangular, Square, and Circular)

10A.3 Member Dimensions

Concrete members which will be designed by the programmust have certainsection properties input under the MEMBER PROPERTY command. These are the D(YD) and b (ZD) dimensions for rectangular or square cross sections and the D (YD)for circular cross sections.

The following is an example the required input:

UNIT MM

MEMBER PROPERTY

1 3 TO 7 9 PRISM YD 450. ZD 250.

11 13 PR YD 350.

In the above input, the first set of members are rectangular (450 mm depth and250 mmwidth) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with a 350 mm diameter.

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Warning: It is absolutely imperative that you do not provide the cross sectionarea (AX) as an input.

10A.4 Slenderness Effects and Analysis Con-siderations

Slenderness effects are extremely important in designing compression members.Slenderness effects result in additional forces being exerted on the column overand above those obtained from the elastic analysis. There are two options bywhich the slenderness effects can be accommodated.

The first option is to compute the secondary moments through an exact analysis.Secondary moments are caused by the interaction of the axial loads and therelative end displacements of a member. The axial loads and joint displacementsare first determined from an elastic stiffness analysis and the secondary momentsare then evaluated.

The second option is to approximately magnify the moments from the elasticanalysis and design the column for the magnified moment. It is assumed that themagnified moment is equivalent to the total moment comprised of the sum ofprimary and secondary moments.

STAAD provides facilities to design according to both of the above methods. Toutilize the first method, the command PDELTA ANALYSIS must be used instead ofPERFORM ANALYSIS in the input file. The user must note that to take advantage ofthis analysis, all the combinations of loading must be provided as primary loadcases and not as load combinations. This is due to the fact that load combinationsare just algebraic combinations of forces and moments, whereas a primary loadcase is revised during the P-delta analysis based on the deflections. Also, note thatthe proper factored loads (like 1.5 for dead load etc.) should be provided by theuser. STAAD does not factor the loads automatically. The second methodmentioned above is utilized by providing the magnification factor as a concretedesign parameter (See the parameter MMAG in Table 10A.1). The column isdesigned for the axial load and total of primary and secondary biaxial moments ifthe first method is used and for the axial load and magnified biaxial moments if thesecond method is used.

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10A.5 Beam Design

Beams are designed for flexure, shear and torsion. The program considers 12equally spaced divisions of the beammember. However this number can beredefined by NSECTION parameter. All these sections are designed for flexure,shear and torsion for all load cases. The results include design results for mostcritical load case.

Example

UNIT KG CM

START CONCRETEDESIGN

CODE JAPAN

FYMAIN SRR295 ALL

FYSEC SRR295 ALL

FC 350 ALL

CLEAR 2.5 MEM2 TO6

TRACK 1.0 MEMB 2 TO 9

DESIGN BEAM 2 TO9

END CONCRETEDESIGN

10A.5.1 Design for Flexure  

Reinforcement for positive and negative moments are calculated on the basis ofsection properties provided by the user. Program first try to design the section for g= 0 and pt = balanced reinforcement ratio. If allowable moment is lower than theactual moment program increases g value for same pt and checks the satisfactoryconditions. If conditions are not satisfied this procedure continues until g reachesto 1.0 and then pt value is increased keeping g = 1.0. This procedure continuesuntil pt reaches to its maximum value( 2 % ). But if the allowable moment for pt =maximum value and g = 1.0 is lower than the actual moment the program givesmessage that the section fails.

This program automatically calculates the Bar size and no. of bars needed to designthe section. It arranges the bar in layers as per the requirements and recalculate theeffective depth and redesign the sections for this effective depth.

Notes:

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a. Beams are designed for MZ only. The moment MY is not considered inflexure design

b. MMAG parameter can be used to increase design moment

c. 1.4 cm. is added to the clear cover to take stirrup size into consideration forflexure design.

d. STAAD beam design procedure is based on the local practice andconsidering the fact that Japan is a high seismic zone area.

10A.5.2 Design for Shear  

The Design Shear value, QD, is evaluated for the beam. The update effective depth

is used to then calculate the allowable shear stress. The allowable shear stress ofconcrete, f

s, is automatically calculated from design load type (permanent or

temporary) and given density of concrete. The program then calculates therequired bar size, aw, and spacing of stirrups. The reinforcement ratio for thestirrup, p

w, is calculated for design Bar size and stirrup pitch and all the necessary

checking is done.

For seismic loading it is needed to increase shear force ≥ 1.5 times the actual valueand this can be done utilizing the Design Shear Modification factor, k (SMAGparameter) without changing the Design Moment.

Notes:

a. Stirrups are always assumed to be 2-legged

b. Governing density to determine Light weight or Normal Weight Concrete is2.3 kg/sq. cm

10A.5.4 Design for Torsion  

Torsion design for beam is optional. If the TORSION parameter value is 1.0, theprogram will design the assigned beam(s) for torsion. The program first checkswhether extra reinforcement is needed for torsion or not. If additionalreinforcement is needed, this additional pt is added to flexure pt and additional Pwis added to shear design Pw.

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10A.6 Column Design

Columns are designed for axial force, MZ moment, MY moment, and shear force.Both the ends of the members are designed for all the load cases and the loadingwhich produces largest amount of reinforcement is called as critical load. If Track 0or Track 1 is used, design results will be printed for critical load only. But if Track 2is used, you can get detailed design results of that member. The value of Pt neededfor minimum axial force, maximum axial force, maximum MZ, maximum MY amongall the load cases for both the ends will be printed. If the MMAG parameter is used,the column moments will be multiplied by that value. If the SMAG parameter is used,column shear force will be multiplied by that value.

Column design is done for Rectangular, Square and Circular sections. Forrectangular and square sections Pt value is calculated separately for MZ and MY,while for circular sections Pg value is calculated for MZ and MY separately.

Column design for biaxial moments is optional. If the BIAXIAL parameter value is1.0, the program will design the column for biaxial moments. Otherwise columndesign is always uniaxial.

Steps involved:

1. Depending on the axial force zone is determined for Pt = 0.0 .

2. If the column is in "zone A", design is performed by increasing Pt andchecking allowable load for that known Pt and known actual eccentricity ofthe column.

3. If the column is in "zone B" or in "zone C", xn is calculated for given P and Ptand checking is done for allowable moment, if allowable moment is less thanthe actual moment, program increases Pt and this procedure continues untilthe column design conditions are satisfied or the column fails as the requiredPt is higher than Pt maximum value.

4. If the column is in tension, design is done by considering allowable tensilestress of steel only.

5. If biaxial design is requested program solve the following interactionequation

6. where, a = 1.0+1.66666666 ´ (ratio-0.2), ratio = P/Pcap & 1.0 £ a £ 2.0,Mycap, Mzcap & Pcap represents section capacity

7. If the interaction equation is not satisfied program increases Pt and calculates

International Design Codes Manual — 607

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Pcap, Mycap and Mzcap and solve the interaction equation again and thisprocess continues until the eqn. is satisfied or the column fails as Pt exceedsits maximum limit.

8. If biaxial design is not requested program assumes that interaction equationis satisfied (if uniaxial design is performed successfully).

9. If the interaction equation is satisfied program determines bar size andcalculates no. of bars and details output is written.

Example

UNIT KGS CMS

START CONCRETEDESIGN

CODE JAPAN

FYMAIN SRR295 ALL

FC 210 ALL

CLEAR 2.5 MEMB 2 TO 6

DESIGN COLUMN 2 TO6

END CONCRETEDESIGN

10A.7 Slab/Wall  Design  

To design a slab or a wall, it must first be modeled using finite elements andanalyzed. The command specifications are in accordance with Chapter 2 andChapter 6 of the Technical Reference Manual.

Elements are designed for the moments Mx and My. These moments are obtainedfrom the element force output (see Chapter 2 of the Technical Reference Manual).The reinforcement required to resist the Mx moment is denoted as longitudinalreinforcement and the reinforcement required to resist the My moment is denotedas transverse reinforcement.

The longitudinal bar is the layer closest to the exterior face of the slab or wall. Thefollowing parameters are those applicable to slab and wall design:

1. FYMAIN— Yield stress for reinforcing steel - transverse and longitudinal.

2. FC— Concrete grade

3. CLEAR— Distance from the outer surface of the element to the edge of the

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bar. This is considered the same on both top and bottom surfaces of theelement.

4. MINMAIN— Minimum required size of longitudinal/transverse reinforcing bar

The other parameters shown in Table 10A.1 are not applicable to slab or walldesign.

10A.8 Design Parameters

The program contains a number of parameters which are needed to perform thedesign. Default parameter values have been selected such that they are frequentlyused numbers for conventional design requirements. These values may be changedto suit the particular design being performed. Table 10A.1 contains a complete listof the available parameters and their default values. It is necessary to declarelength and force units as centimeters and Kilograms before performing the concretedesign.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as JAPAN.

Design Code to follow. See section5.52.2 of the Technical ReferenceManual.

BIAXIAL 0.0 Value to define biaxial or uniaxialdesign type for Column

0. uniaxial design only

1. design for biaxial moments

CLEAR 3.0 cm(beam)

4.0 cm

(Column)

Clear cover for Beam or clear sidecover for column.

Table 10A.1 - Japanese Concrete Design Parameters

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ParameterName

DefaultValue

Description

DEPTH YD Depth of concrete member. Thisvalue defaults to YD as providedunder MEMBER PROPERTIES.

EFACE 0.0 Face of support location at end ofbeam. (Note: Both SFACE & EFACEare input as positive numbers).

FC 210 Kg/cm2 Compressive Strength of Concrete.

FYMAIN SR235 Steel grade. Acceptable values forsteel grade and their associatedyield stress values are shown in thefollowing table. Programautomatically calculates yield stressvalue depending on design loadtype (permanent or temporary).

FYSEC SR235 Same as FYMAIN except this is forsecondary steel.

LONG 0.0 Value to define design load type

0. Permanent Loading

1. Temporary Loading

MAXMAIN 41.0 cm Maximummain reinforcement barsize

MAXSEC 41.0 cm Maximum secondary reinforcementbar size.

MINMAIN 10 mm Minimummain reinforcement barsize.

MINSEC 10 mm Minimum secondary reinforcementbar size.

MMAG 1.0 Design moment magnificationfactor

NSECTION 12 Number of equally-spaced sections

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ParameterName

DefaultValue

Description

to be considered in finding criticalmoments for beam design.

REINF 0.0 Tied Column. A value of 1.0 willmean spiral.

SFACE 0.0 Face of support location at start ofbeam.

SMAG 1.0 Design shear magnification factor

TORSION 0.0 Value to request for torsion designfor beam

0. torsion design not needed

1. torsion design needed

TRACK 0.0 Beam Design:

0. Critical section design results.

1. Five section design results &design forces.

2. 12 section design results &design forces.

Column Design:

1. Detail design results for crit-ical load case only.

2. Design results for minimumP, maximum P, maximum MZand maximum MY among allload cases for both ends.

WIDTH ZD Width of concrete member. Thisvalue defaults to ZD as providedunder MEMBER PROPERTIES.

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SteelGrade

Long Term Loading Short Term Loading

Tension& Compression

Shear Rein-forcement

Tension& Compression

Shear Rein-forcement

SR235SRR235SDR235

1600 1600 2400 2400

SR295SRR295

1600 2000 3000 3000

SD295ASD295BSDR295

2000 2000 3000 3000

SDR345SD345

2200 (2000) 2000 3500 3500

SD390 2200 (2000) 2000 4000 4000

Table 10A.2 - Table of permissible Steel Grades and associated Yield Stresses forFYMAIN and FYSEC parameters

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Japanese Codes - Steel Design Per 2005 AIJ

10B.(A) Japanese Codes - Steel Design Per2002 AIJ

10B.1(A)   General

This section presents some general statements regarding the implementation of the“Architectural Institute of Japan” (AIJ) specifications for structural steel design(1986 and 2002 editions) in STAAD. The design philosophy and procedurallogistics are based on the principles of elastic analysis and allowable stress design.Facilities are available for member selection as well as code checking. Two majorfailure modes are recognized: failure by overstressing and failure by stabilityconsiderations. The following sections describe the salient features of the designapproach.

Members are proportioned to resist the design loads without exceedance of theallowable stresses or capacities and the most economical section is selected on thebasis of the least weight criteria. The code checking part of the program also checksthe slenderness requirements and the stability criteria. Users are recommended toadopt the following steps in performing the steel design:

l Specify the geometry and loads and perform the analysis.

l Specify the design parameter values if different from the default values.

l Specify whether to perform code checking or member selection.

10B.2(A)   Analysis  Methodology

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loading specificationsand in using appropriate load factors to create necessary loading situations.Depending upon the analysis requirements, regular stiffness analysis or P-Deltaanalysis may be specified. Dynamic analysis may also be performed and the resultscombined with static analysis results.

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10B.3(A) Member Property Specifications

For specification of member properties of standard Japanese steel shapes, thesteel section library available in STAAD may be used. The next section describesthe syntax of commands used to assign properties from the built-in steel table.Members properties may also be specified using the User Table facility. For moreinformation on these facilities, refer to Section 1.7 the STAAD Technical ReferenceManual.

10B.4(A) Built-in Japanese Steel Section Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, these properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredfor these members during the analysis. An example of member propertyspecification in an input file is provided at the end of this section.

A complete listing of the sections available in the built-in steel section library maybe obtained using the tools of the graphical user interface.

Following are the descriptions of different types of sections.

I shapes

I shapes are specified in the following way:

Note: While specifying the web thickness, the portion after the decimal pointshould be excluded.

1 TO 9 TA ST I300X150X11

12 TO 15 TA ST I350X150X9  

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H shapes

H shapes are specified as follows:

Note: While specifying the web thickness, the portion after the decimal pointshould be excluded.

1 TO 8 TA ST H200X100X4

13 TO 17 TA ST H350X350X12

T shapes

T shapes are specified as follows:

Note: While specifying the web thickness, the portion after the decimal pointshould be excluded.

20 TO 25 TA ST T250X19

Channels

Channel sections are specified as follows.

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25 TO 34 TA ST C125X65X6

46 TO 49 TA ST C200X90X8

Double Channels

Back to back double channels, with or without a spacing in between them, areavailable. The letter D in front of the section name is used to specify a doublechannel.

17 TO 27 TA D C300X90X10

45 TO 76 TA D C250X90X11 SP 2.0

In the above commands, members 17 to 27 are a back-to-back double channelC300X90X10 with no spacing in between. Members 45 to 76 are a double channelC250X90X11 with a spacing of 2 length units.

Angles

Two types of specification may be used to describe an angle. The standard anglespecification is as follows.

The letter L (signifying that the section is an angle) is followed by the length of thelegs and then the thickness of the leg, all in millimetres. The word ST signifies thatthe section is a STandard angle meaning that the major principal axis coincideswith the local YY axis specified in Chapter 1 of Section 1.5.2 of the User's Manual.

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1 4 TA ST L150X90X9

If the minor principal axis coincides with the local YY axis specified in Chapter 2 ofthe User's Manual, the word RA (Reverse Angle) should be used instead of ST asshown below.

7 TO 23 TA RA L90X75X9

Double angles

Short leg back-to-back and long leg back-to-back double angles may be specifiedby using the words SD or LD in front of the angle size. In the case of an equalangle, either SD or LD will serve the purpose. The spacing between the angles maybe specified by using the word SP after the angle size followed by the value of thespacing.

8 TO 25 TA SD L100X65X7 SP 2.0

36 TO 45 TA LD L300X90X11 SP 3.0

The first example indicates a short legs back-to-back double angle comprised of100X65X7 angles separated by 2 length units. The latter is a long legs back-to-backdouble angle comprised of 300X90X11 angles separated by 3 length units.

Tubes

Tube names are input by their dimensions. For example,

6 TA ST TUBEDT 8.0WT 6.0 TH 0.5

is a tube that has a height of 8 length units, width of 6 length units and a wallthickness of 0.5 length units. Only code checking, no member selection can beperformed on TUBE sections.

Pipes (Circular Hollow sections)

Circular hollow sections may be provided by specifying the word PIPE followed bythe outside and inside diameters of the section. For example,

1 TO 9 TA ST PIPE OD 25.0 ID 20.0

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specifies a pipe with outside diameter of 25 length units and an inside diameter of20 length units. Only code checking, no member selection, can be performed onPIPE sections.

Sample Input file containing Japanese shapes

STAAD SPACE

UNIT KIP FEET

JOINT COORD

1 0 0 0 12 11 0 0

MEMB INCIDENCE

1 1 2 11

UNIT INCH

MEMBER PROPERTY JAPANESE

* H-SHAPE

1 TA ST H200X100X4

* I SHAPE

2 TA ST I250X125X10

* T SHAPE

3 TA ST T200X19

* CHANNEL

4 TA ST C125X65X6

* DOUBLE CHANNEL

5 TA D C200X90X8

* REGULAR ANGLE

6 TA ST L100X75X7

* REVERSE ANGLE

7 TA RA L90X75X9

* DOUBLE ANGLE - LONG LEG BACK TOBACK

8 TA LD L125X75X7 SP 2.0

* DOUBLE ANGLE - SHORT LEG BACK TOBACK

9 TA SD L300X90X11 SP 1.5

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* TUBE

10 TA ST TUBEDT 3.0WT 2.5 TH 0.25

* PIPE

11 TA ST PIPE OD 3.0 ID 2.5

PRINT MEMBER PROPERTIES

FINISH

10B.5(A) Member Capacities

Member design and code checking per AIJ 2002 are based upon the allowablestress design method. It is a method for proportioning structural members usingdesign loads and forces, allowable stresses, and design limitations for theappropriate material under service conditions. The basic measure of membercapacities are the allowable stresses on the member under various conditions ofapplied loading such as allowable tensile stress, allowable compressive stress etc.These depend on several factors such as cross sectional properties, slendernessfactors, unsupported width to thickness ratios and so on. Explained here is theprocedure adopted in STAAD for calculating such capacities. 

Design Capabilities

All types of available shapes like H-Shape, I-Shape, L-Shapes, CHANNEL, PIPE,TUBE, Prismatic section etc. can be used as member property and STAAD willautomatically adopt the design procedure for that particular shape if Steel Design isrequested. STEEL TABLE available within STAAD or UPTABLE facility can be usedfor member property.

Methodology

For steel design, STAAD compares the actual stresses with the allowable stresses asrequired by AIJ specifications. The design procedure consist of following threesteps.

1. Calculation of sectional properties

The program extract sectional properties like sectional area ( A ), Moment ofInertia about Y axis and Z axis ( Iyy, Izz) from in-built Japanese Steel Table

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and calculates Zz, Zy, iy, iz using appropriate formula. For calculation of i (radius of gyration needed for bending ), program calculates moment ofinertia ( Ii )and sectional area ( Ai ) for 1/6th section and then uses followingformula:

i = √(Ii/Ai)

Note: The above mentioned procedure for calculation of i is applicablefor I shape, H shape and Channel sections.

2. Calculation of actual and allowable stresses

Allowable stresses for structural steel under permanent loading shall bedetermined on the basis of the values of F given in the following table.

Steel for Con-struction Struc-

tures

Steel for General Structures Steel for Welded Structures

Thickness SN400

SNR400

STKN400

SN490

SNR490

STKN490

SN490

SNR490

STKN490

SS400

STK400

STKR400

SSC400

SS490 SS540 SM400

SMA400

SM520 SM570

t≤ 40 235 325 235 275 375 235 325 355 400

40< t ≤100

215 295 215 255 - 215 295 335 400

Table 10B.1 - Table: Values of F (N/mm2)

Note: In checking members for temporary loading be the combinationof stresses described in Chap.3, allowable stresses specified in thischapter may be increases by 50%

Program calculates actual and allowable stresses by following methods:

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i. Axial Stress:

Actual tensile stresses ( FT) = Force / ( A x NSF ), 

NSF = Net Section Factor for tension

Actual compressive stress ( FC) = Force / A

Allowable tensile stress ( ft)

= F / 1.5 (For Permanent Case)

= F ( For Temporary Case )

Allowable compressive stress

(fc) = {1 - 0.4x(λ/Δ2)} x F/v when λ ≤ Δ

= 2.77 x F/ (λ/Δ2) when λ > Δ

= fcx 1.5 (for Temporary case)

where:

Δ = √(π2E/(.6 x F))

Δ = F

v = 3/2 + 2/3x(λ/Δ2)

ii. Bending Stress:

Actual bending stress for My for compression 

( Fbcy) = M

y/ Z

cy

Actual bending stress for Mz for compression

( Fbcz) = M

z/ Z

cz

Actual bending stress for My for tension

( Fbty

) = My/ Z

ty

Actual bending stress for Mz for tension

( Fbtz

) = Mz/ Z

tz

Where:

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Zcy, Zczare section modulus for compression

Zty, Ztzare section modulus for tension

Allowable bending stress for My

(fbcy) = f

t

Allowable bending stress for Mz

(fbcz) = { 1 - .4 x (lb / i)2 / (C λ2)} ft max

= 900/ (lb x h / Af )

For Temporary case, fbcz= 1.5 x (f

bczfor Permanent case)

Where:

C = 1.75 - 1.05 (M2 / M1) + 0.3 (M2 / M1)2

Allowable bending stress for My, fbty= f

t

Allowable bending stress for Mz, fbtz= f

bcz

Note: The parameter CB can be used to specify a value for Cdirectly.

iii. Shear Stress

Actual shear stresses are calculated by the following formula:

qy= Q

y/ A

ww

Where:

Aww

= web shear area = product of depth and webthickness

qz= Q

z/ A

ff

Where:

Aff= flange shear area = 2/3 times total flange area

Allowable shear stress, fs= F

s/ 1.5, F

s= F / √(3)

3. Checking design requirements:

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User provided RATIO value (default 1.0) is used for checking designrequirements 

The following conditions are checked to meet the AIJ specifications. For allthe conditions calculated value should not be more than the value of RATIO.If for any condition value exceeds RATIO , program gives the message thatthe section fails.

1. Checking design requirements:

User provided RATIO value (default 1.0) is used for checking designrequirements 

The following conditions are checked to meet the AIJ specifications. Forall the conditions calculated value should not be more than the value ofRATIO. If for any condition value exceeds RATIO, program gives themessage that the section fails.

Conditions:

i. Axial tensile stress ratio = FT/ ft

ii. Axial compressive stress ratio = FC/ fc

iii. Combined compression & bending ratio = FC/

fc+F

bcz/fbcz+F

bcy/fbcy

iv. Combined compression & bending ratio = (Fbtz+F

bty-FC) / f

tv. Combined tension & bending ratio = (F

T+F

btz+F

bty) / f

tvi. Combined tension & bending ratio = F

bcz/fbcz+F

bcy/fbcy- F

T/ft

vii. Shear stress ratio for qy= q

y/ fs

viii. Shear stress ratio for qz= q

z/ fs

ix. von Mises stress ratio (if the von Mises stresses were set to bechecked) = f

m/(k f

t)

Output Format ( TRACK 3 )

One new output format has been introduced which provides details step by stepinformation of Steel Design for guiding load case only. If Section command is usedbefore Parameter command this output will provide details information for all thesections specified by Section Command.

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Note: This output format is available only when the BEAM parameter value is 0and the TRACK parameter value is 3. If section command is not used designinformation will be printed for two ends only. If Member Truss option is usedno Shear Design information will be printed.

Example:

SECTION 0.0 0.25 0.5 0.75 1.0 ALL

PARAMETER

CODE JAPANESE 2002

BEAM 0.0 ALL

TMP 0.0 MEMB 1 TO 4

TMP 1.0 MEMB 5 TO 8

TRACK 3 ALL

CHECK CODE ALL

FINISH

Allowable stress for Axial Tension

Allowable axial stress in tension is calculated per section 5.1 (1) of the AIJ code. Inmembers with axial tension, the tensile load must not exceed the tension capacityof the member. The tension capacity of the member is calculated on the basis ofthe member area. STAAD calculates the tension capacity of a given member basedon a user supplied net section factor (NSF-a default value of 1.0 is present but maybe altered by changing the input value, see Table 8B.1) and proceeds withmember selection or code checking.

Allowable stress for Axial Compression

The allowable stress for members in compression is determined according to theprocedure of section 5.1 (3). Compressive resistance is a function of theslenderness of the cross-section (Kl/r ratio) and the user may control theslenderness value by modifying parameters such as KY, LY, KZ and LZ. In theabsence of user provided values for effective length, the actual member length willbe used. The slenderness ratios are checked against the permissible valuesspecified in Chapter 11 of the AIJ code.

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Allowable stress for Bending

The permissible bending compressive and tensile stresses are dependent on suchfactors as length of outstanding legs, thickness of flanges, unsupported length ofthe compression flange (UNL, defaults to member length) etc.  The allowablestresses in bending (compressive and tensile) are calculated as per the criteria ofClause 5.1 (4) of the code.

Allowable stress for Shear

Shear capacities are a function of web depth, web thickness etc. The allowablestresses in shear are computed according to Clause 5.1 (2) of the code.

10B.6(A) Combined Loading

For members experiencing combined loading (axial force, bending and shear),applicable interaction formulas are checked at different locations of the member forall modeled loading situations. Members subjected to axial tension and bending arechecked using the criteria of clause 6.2. For members with axial compression andbending, the criteria of clause 6.1 is used.

10B.7(A) Design Parameters

The user is allowed complete control over the design process through the use ofparameters mentioned in Table 9B.1 of this chapter. These parameterscommunicate design decisions from the engineer to the program. The defaultparameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements of thesituation, some or all of these parameter values may have to be changed to exactlymodel the physical structure.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as JAPANESE

Table 10B.2 - Japanese Steel Design Parameters

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ParameterName

DefaultValue

Description

2002 to invoke the AIJ 2002.

Design Code to follow. See section5.48.1 of the Technical ReferenceManual.

BEAM 0.0 Locations of design:

0. Design only for end momentsor those at locations specifiedby the SECTION command.

1. Calculate moments at twelfthpoints along the beam, anduse the maximum Mz locationfor design.

CB 0 C value from the AIJ code. See"10B.5(A) Member Capacities" onpage 619 Bending Stress for how Cis calculated and applied.

Use 0.0 to direct the program tocalculated Cb.

Any other value be used in lieu ofthe program calculated value.

DFF None(Mandatory

fordeflectioncheck)

"Deflection Length" / Maxm.allowable local deflection

DJ1 Start Jointof member

Joint No. denoting starting pointfor calculation of "DeflectionLength" (See Note a)

DJ2 End Joint ofmember

Joint No. denoting end point forcalculation of "Deflection Length"(See Note a)

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ParameterName

DefaultValue

Description

DMAX 100 cm Maximum allowable depth formember.

DMIN 0.0 cm Minimum allowable depth formember.

KY 1.0 K value in local y-axis. Usually, thisis the minor axis.

KZ 1.0 K value in local z-axis. Usually, thisis the major axis.

LY MemberLength

Length in local y-axis to calculateslenderness ratio.

LZ MemberLength

Same as above except in z-axis

FYLD 235 MPA Yield strength of steel inMegapascal.

MAIN 0.0 Check for slenderness:

0. Perform check for slen-derness

1. Suppress slenderness check

MISES 0 Option to include check for vonMises stresses

0. Do not include check.

1. Perform Von Mises stresscheck.

NSF 1.0 Net section factor for tensionmembers.

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

SSY 0.0 Sidesway:

0. Sidesway in local y-axis.

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ParameterName

DefaultValue

Description

1. No sidesway

SSZ 0.0 Same as above except in local z-axis.

TMAIN 400 Allowable Slenderness Limit forTension Member

1.0 = suppress slenderness check .

Any value greater than 1 =Allowable KL/r in tension.

TMP 0 Loading condition:

0. Permanent Loading

1. Temporary Loading

TRACK 0.0 Level of output detail:

0. = Suppress critical memberstresses

1. = Print all critical memberstresses

2. = Print expanded output

3. = Print maximum details.

Note: Only producesresults when BEAM 0 isused.

4. = Perform and print deflec-tion check.

UNL MemberLength

Unsupported length for calculatingallowable bending stress.

UNF 1.0 Same as above provided as afraction of actual member length.

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Notes

a. "Deflection Length" is defined as the length that is used for calculation of localdeflections within a member.  It may be noted that for most cases the"Deflection Length" will be equal to the length of the member. However, insome situations, the "Deflection Length" may be different. A straight linejoining DJ1 and DJ2 is used as the reference line from which local deflectionsare measured.

For example, refer to the figure below where a beam has been modeled usingfour joints and three members. The “Deflection Length” for all three memberswill be equal to the total length of the beam in this case. The parameters DJ1and DJ2 should be used to model this situation. Thus, for all three membershere, DJ1 should be 1 and DJ2 should be 4.

D = Maximum local deflection for members 1, 2, and 3.

PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

b. If DJ1 and DJ2 are not used, "Deflection Length" will default to the memberlength and local deflections will be measured from original member line.

c. The above parameters may be used in conjunction with other available param-eters for steel design.

10B.8 Code Checking

The purpose of code checking is to check whether the provided section propertiesof the members are adequate to carry the forces transmitted to it by the loads onthe structure. The adequacy is checked per the AIJ requirements.

Code checking is done using forces and moments at specified sections of themembers. If the BEAM parameter for a member is set to 1, moments are calculated

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at every twelfth point along the beam, and the maximummoment about the majoraxis is used. When no sections are specified and the BEAM parameter is set to zero(default), design will be based on the forces at the start and end joints of themember. The code checking output labels the members as PASSed or FAILed. Inaddition, the critical condition, governing load case, location (distance from startjoint) and magnitudes of the governing forces and moments are also printed.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

10B.9 Member Selection

The member selection process basically involves determination of the least weightmember that PASSes the code checking procedure based on the forces andmoments obtained from  the most recent analysis. The section selected will be ofthe same type as that specified initially. For example, a member specified initiallyas a channel will have a channel selected for it. Selection of members whoseproperties are originally provided from a user table will be limited to sections inthe user table.

Note: Member selection cannot be performed on TUBES, PIPES, or memberslisted as PRISMATIC.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

Sample Input data for Steel Design

UNIT METER

PARAMETER

CODE JAPANESE 2002

NSF 0.85 ALL

UNL 10.0 MEMBER 7

KY 1.2 MEMBER 3 4

RATIO 0.9 ALL

TRACK 1.0 ALL

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CHECK CODE ALL

SELECT ALL

10B.10(A) Von Mises Stresses Check

Note: This feature requires STAAD.Pro V8i (SELECTseries 2) build 2007.07 orhigher.

The von Mises stress equation shown below, which is modified for beam elementsbased on the corresponding equation in AIJ steel design code (both 2002 and 2005editions of AIJ), indicates that the left-hand side in the equation should be less thanunity. These checks are performed at locations indicated by the BEAM parameter.The default is set that this check is not performed. The MISES parameter must beset to 1 to initiate the checks.

Note: As with other design checks, the unity check value can be modified byuse of the RATIO parameter.

The von Mises stresses are evaluated and checked as follows:

Where:

Longitudinal stress in beam element:

Fx= Axial force

My= Bending moment about y-axis

Mz= Bending moment about z-axis

Ax= Cross-sectional area,

Zy= Section modulus about y-axis

Zz= Section modulus about z-axis

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Mx= Torsional moment

Fy= shear stress in y direction

Fz= shear stress in z direction

Zx= Torsional section modulus = 2I

x/Dx

Dx= Depth of the member

Ix= Torsional constant

Ay= Effective shear area in the y direction

Az= Effective shear area in the z direction

ft= Allowable tensile stress

k = Loading duration factor, as specified by the TMP parameter (1.0 forpermanent and 1.5 for temporary).

In the STRESSES output category, stress value of (numerator of the von Misesstress equation) is output as the value of fm. Along with slenderness ratios,stresses, and deflections, von Mises stress equation is checked. When its left-handside yields the maximum ratio value, it is printed as RATIO and “VON MISES” isprinted as CRITICAL COND.

Japanese Codes - Steel Design Per 2005AIJ

10B.1(B) General

This section presents some general statements regarding the implementation ofthe “Architectural Institute of Japan” (AIJ) specifications for structural steel design(2005 edition) in STAAD. The design philosophy and procedural logistics arebased on the principles of elastic analysis and allowable stress design. Facilities areavailable for member selection as well as code checking. Two major failure modesare recognized: failure by overstressing and failure by stability considerations. Thefollowing sections describe the salient features of the design approach.

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Members are proportioned to resist the design loads without exceedance of theallowable stresses or capacities and the most economical section is selected on thebasis of the least weight criteria. The code checking part of the program also checksthe slenderness requirements and the stability criteria. Users are recommended toadopt the following steps in performing the steel design:

l Specify the geometry and loads and perform the analysis.

l Specify the design parameter values if different from the default values.

l Specify whether to perform code checking or member selection.

The method for calculating allowable bending stress was updated for the AIJ 2005from the AIJ 2002 code. All other allowable limit states, analysis and designmethods, etc., remain unchanged. Refer to the AIJ 2002 documentation foradditional details.

10B.2(B) Member Capacities

Member design and code checking per AIJ 2005 are based upon the allowablestress design method. It is a method for proportioning structural members usingdesign loads and forces, allowable stresses, and design limitations for theappropriate material under service conditions. The basic measure of membercapacities are the allowable stresses on the member under various conditions ofapplied loading such as allowable tensile stress, allowable compressive stress etc.These depend on several factors such as cross sectional properties, slendernessfactors, unsupported width to thickness ratios and so on. Explained here is theprocedure adopted in STAAD for calculating such capacities. 

Design Capabilities

All types of available shapes like H-Shape, I-Shape, L-Shapes, CHANNEL, PIPE,TUBE, Prismatic section etc. can be used as member property and STAAD willautomatically adopt the design procedure for that particular shape if Steel Design isrequested. STEEL TABLE available within STAAD or UPTABLE facility can be usedfor member property.

Methodology

For steel design, STAAD compares the actual stresses with the allowable stresses asrequired by AIJ specifications. The design procedure consist of following three

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steps.

1. Calculation of sectional properties

The program extract sectional properties like sectional area ( A ), Moment ofInertia about Y axis and Z axis ( I

yy, Izz) from in-built Japanese Steel Table

and calculates Zz, Zy, iy, izusing appropriate formula. For calculation of i (

radius of gyration needed for bending ), program calculates moment ofinertia ( I

i)and sectional area ( A

i) for 1/6th section and then uses following

formula:

i = √(Ii/Ai)

Note: The above mentioned procedure for calculation of i is applicablefor I shape, H shape and Channel sections.

2. Calculation of actual and allowable stresses

Program calculates actual and allowable stresses by following methods:

i. Axial Stress:

Actual tensile stresses ( FT) = Force / ( A x NSF ), 

NSF = Net Section Factor for tension

Actual compressive stress ( FC) = Force / A

Allowable tensile stress ( ft)

= F / 1.5 (For Permanent Case)

= F ( For Temporary Case )

Allowable compressive stress

(fc) = {1 - .4x(λ/Δ2)} x F/v when λ ≤ Δ

= 2.77 x F/ (

= fcx 1.5 (for Temporary case)

Where:

Δ = √(π2E/(.6 x F))

Δ = F

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v = 3/2 + 2/3x(λ/Δ2)

ii. Bending Stress:

Actual bending stress for My for compression:

( Fbcy) = M

y/ Z

cy

Actual bending stress for Mz for compression

( Fbcz) = M

z/ Z

cz

Actual bending stress for My for tension

( Fbty

) = My/ Z

ty

Actual bending stress for Mz for tension

( Fbtz

) = Mz/ Z

tz

Where:

Zcy, Zczare section modulus for compression

Zty, Ztzare section modulus for tension

Allowable bending stress for My

(fbcy) = f

t

Allowable bending stress for Mz

When λb≤pλb, fb= F/ν

Whenpλb< λ

b≤eλb,

Wheneλb< λ

b,

Where:

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For Temporary case, fbcz= 1.5 x (f

bczfor Permanent case)

Where:

C = 1.75 - 1.05 (M2 / M1) + 0.3 (M2 / M1)2

Allowable bending stress for My, fbty= f

t

Allowable bending stress for Mz, fbtz= f

bcz

Note: The parameter CB can be used to specify a value for Cdirectly.

iii. Shear Stress

Actual shear stresses are calculated by the following formula:

qy= Q

y/ A

ww

Where:

Aww

= web shear area = product of depth and webthickness

qz= Q

z/ A

ff

Where:

Aff= flange shear area = 2/3 times total flange area

Allowable shear stress, fs= F

s/ 1.5, F

s= F / √(3)

3. Checking design requirements:

User provided RATIO value (default 1.0) is used for checking designrequirements:

The following conditions are checked to meet the AIJ specifications. For allthe conditions calculated value should not be more than the value of RATIO.If for any condition value exceeds RATIO, program gives the message thatthe section fails.

Conditions:

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i. Axial tensile stress ratio = FT/ ft

ii. Axial compressive stress ratio = FC/ fc

iii. Combined compression & bending ratio = FC/ fc+F

bcz/fbcz+F

bcy/fbcy

iv. Combined compression & bending ratio = (Fbtz+F

bty-FC) / f

tv. Combined tension & bending ratio = (F

T+F

btz+F

bty) / f

tvi. Combined tension & bending ratio = F

bcz/fbcz+F

bcy/fbcy- F

T/ft

vii. Shear stress ratio for qy= q

y/ fs

viii. Shear stress ratio for qz= q

z/ fs

ix. von Mises stress ratio (if the von Mises stresses were set to bechecked) = f

m/(k f

t)

Note: All other member capacities (axial tension, axial compression, and shear)are calculated as for AIJ 2002. See "10B.5(A) Member Capacities" on page 619

10B.3(B) Design Parameters

You are allowed complete control over the design process through the use ofparameters mentioned in Table 10B.3 of this chapter. These parameterscommunicate design decisions from the engineer to the program. The defaultparameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements of thesituation, some or all of these parameter values may have to be changed to exactlymodel the physical structure.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CODE - Must be specified as JAPANESE2005 to invoke the AIJ 2005.

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM 0.0 0.0 =  design only for endmoments or those at locationsspecified by the SECTIONcommand.

1.0 =  calculate moments at twelfthpoints along the beam, and use themaximum Mz location for design.

CB 0 C value from the AIJ code. See"10B.5(A) Member Capacities" onpage 619 Bending Stress for how Cis calculated and applied.

Use 0.0 to direct the program tocalculated Cb.

Any other value be used in lieu ofthe program calculated value.

DFF None(Mandatory

fordeflectioncheck)

"Deflection Length" / Maxm.allowable local deflection

DJ1 Start Jointof member

Joint No. denoting starting pointfor calculation of "DeflectionLength" (See Note a)

Table 10B.3 - Japanese Steel Design Parameters

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ParameterName

DefaultValue

Description

DJ2 End Joint ofmember

Joint No. denoting end point forcalculation of "Deflection Length"(See Note a)

DMAX 100 cm Maximum allowable depth formember.

DMIN 0.0 cm Minimum allowable depth formember.

FYLD 235 MPA Yield strength of steel inMegapascal.

KY 1.0 K value in local y-axis. Usually, thisis the minor axis.

KZ 1.0 K value in local z-axis. Usually, thisis the major axis.

LY MemberLength

Length in local y-axis to calculateslenderness ratio.

LZ MemberLength

Same as above except in z-axis

MAIN 0.0 0.0 =  check for slenderness

1.0 =  suppress slenderness check

MISES 0 Option to include check for vonMises stresses

0 = Do not include check.

1 = Perform Von Mises stresscheck.

NSF 1.0 Net section factor for tensionmembers.

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

SSY 0.0 0.0 =  Sidesway in local y-axis.

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ParameterName

DefaultValue

Description

1.0 =  No sidesway

SSZ 0.0 Same as above except in local z-axis.

TMAIN 400 Allowable Slenderness Limit forTension Member

1.0 = suppress slenderness check .

Any value greater than 1 =Allowable KL/r in tension.

TMP 0 0 = Permanent Loading

1 = Temporary Loading

TRACK 0.0 Level of output detail:

0. = Suppress critical memberstresses

1. = Print all critical memberstresses

2. = Print expanded output

3. = Print maximum details.

Note: Only producesresults when BEAM 0 isused.

4. = Perform and print deflec-tion check.

UNF 1.0 Same as above provided as afraction of actual member length.

UNL MemberLength

Unsupported length for calculatingallowable bending stress.

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Notes

a. "Deflection Length" is defined as the length that is used for calculation of localdeflections within a member.  It may be noted that for most cases the"Deflection Length" will be equal to the length of the member. However, insome situations, the "Deflection Length" may be different. A straight linejoining DJ1 and DJ2 is used as the reference line from which local deflectionsare measured.

For example, refer to the figure below where a beam has been modeled usingfour joints and three members. The “Deflection Length” for all three memberswill be equal to the total length of the beam in this case. The parameters DJ1and DJ2 should be used to model this situation. Thus, for all three membershere, DJ1 should be 1 and DJ2 should be 4.

D = Maximum local deflection for members 1, 2, and 3.

PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

b. If DJ1 and DJ2 are not used, "Deflection Length" will default to the memberlength and local deflections will be measured from original member line.

c. The above parameters may be used in conjunction with other available param-eters for steel design.

10B.4(B) Von Mises Stresses Check

Note: This feature requires STAAD.Pro V8i (SELECTseries 2) build 2007.07 orhigher.

The von Mises stress equation shown below, which is modified for beam elementsbased on the corresponding equation in AIJ steel design code (both 2002 and 2005

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editions of AIJ), indicates that the left-hand side in the equation should be lessthan unity. These checks are performed at locations indicated by theBEAM parameter. The default is set that this check is not performed. TheMISES parameter must be set to 1 to initiate the checks.

Note: As with other design checks, the unity check value can be modified byuse of the RATIO parameter.

The von Mises stresses are evaluated and checked as follows:

Where:

Longitudinal stress in beam element:

Fx= Axial force

My= Bending moment about y-axis

Mz= Bending moment about z-axis

Ax= Cross-sectional area,

Zy= Section modulus about y-axis

Zz= Section modulus about z-axis

Mx= Torsional moment

Fy= shear stress in y direction

Fz= shear stress in z direction

Zx= Torsional section modulus = 2I

x/Dx

Dx= Depth of the member

Ix= Torsional constant

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Ay= Effective shear area in the y direction

Az= Effective shear area in the z direction

ft= Allowable tensile stress

k = Loading duration factor, as specified by the TMP parameter (1.0 forpermanent and 1.5 for temporary).

In the STRESSES output category, stress value of (numerator of the von Misesstress equation) is output as the value of fm. Along with slenderness ratios,stresses, and deflections, von Mises stress equation is checked. When its left-handside yields the maximum ratio value, it is printed as RATIO and “VON MISES” isprinted as CRITICAL COND.

10B.5(B) Verification Problems

In the next few pages are included verification examples for reference purposes.

Verification Problem No. 1

Title

A slender, cantilever beam subjected to a load at the end

Type

Static analysis, 3D beam element.

Reference

Problem

A cantilever beam of length 2 meter is subjected to a permanent joint load of 3 kNin the Y direction and 2 kN in the Z direction as well as a 0.008 kN·m torque appliedat the end. Axial tension of 10 kN is also applied to the member. An H100x50x5section is used from the Japanese steel tables.

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Given

Section properties

Dx= 100 mm

Ix= 15,000 mm4

Ax= 1185 mm2, A

y= 500 mm2, A

z= 467 mm2

Zx= 2I

x/Dx= 2·15000/100 = 300 mm3, Z

y= 5920 mm3, Z

z= 37400

mm3

The maximum of the left hand side of the von Mises stress equation apparentlyoccurs at the fixed end of the beam. Section forces at the fixed end are ass follow:

10.0 kN (Tension)

6.0 kN·m (Bending-Y)

6.0 kN·m (Bending-Z)

3.0 kN (Shear-Y)

2.0 kN (Shear-Z)

-0.008 kN·m (Torsion

Member Length L = 2 m, Unbraced length = 100mm.

Material

FYLD = 300 MPa

E = 2.05E+05 MPa

G = E/2.6 MPa

Solution

From these section forces, σxand τ

xyat the section of the fixed end are calculated

as follows:

= 8.44 + 101.35 +24.06 = 133.85 N/mm2

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= 26.67 + √(62 +4.282) = 33.04 N/mm2

From σxand τ

xy, fmis calculated:

fm= √ ( σ

x2+3·τ

xy2) = √[(133.85)2+3·(33.04)2] = 146.26 N/mm2

Since ft= FYLD/1.5 = 300.0 MPa/15 = 200.0 N/mm2 and k = 1 for permanent

loading,

Ratio = 146.26/(200.0 · 1) = 0.731 < 1, So OK.

Comparison

Hand Cal-culation

STAAD.ProResult

Comments

von Mises Stress(fm)

146.26 N/mm2 146.3 N/mm2 None

Table 10B.4 - Comparison of results for a AIJ 2005 verificationproblem

STAAD Input File

STAAD SPACE VERIFICATION EXAMPLE NO.1

START JOB INFORMATION

ENGINEER DATE 18-AUG-10

END JOB INFORMATION

* VERIFICATION FOR VON MISES STRESSES IN AIJ 2005

UNIT MMS KN

JOINT COORDINATES

1 0 0 0; 2 300 0 0

MEMBER INCIDENCES

1 1 2

UNIT METER KN

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DEFINEMATERIAL START

ISOTROPIC STEEL

E 2.05E+008

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTY JAPANESE

1 TABLE ST H100X50X5

UNIT MMS KN

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

UNIT METER KN

LOAD 1 LC1

JOINT LOAD

2 FX 10 FY 3 FZ 2 MX 0.008

PERFORMANALYSIS

LOAD LIST 1

PRINT MEMBER FORCES LIST 1

PARAMETER 1

CODE JAPANESE 2005

TMP 0 ALL

UNL 0.002 ALL

MISES 1 ALL

TRACK 2 ALL

FYLD 300000 ALL

CHECK CODE ALL

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FINISH

Output

The TRACK 2.0 output portion is as follows:STAAD.PRO CODE CHECKING - ( AIJ 2005)********************************************

|--------------------------------------------------------------------------|| Y PROPERTIES ||************* | IN CM UNIT || * |=============================| ===|=== ------------ ||MEMBER 1 * | JAPANESE SECTIONS | | AX = 11.85 || * | ST H100X50X5 | | --Z AY = 5.00 ||DESIGN CODE * | | | AZ = 4.67 || AIJ-2005 * =============================== ===|=== ZY = 5.92 || * ZZ = 37.40 || * |<---LENGTH (ME= 0.30 --->| iY = 1.12 ||************* iZ = 3.97 || ZX = 0.30 || 0.90(KN-MET) ||PARAMETER |L1 STRESSES ||IN N MM | L1 L1 IN N MM||--------------- + L1 L1 -------------|| KL/R-Y= 26.8 | L1 FA = 189.5 || KL/R-Z= 7.6 + L1 fa = 8.4 || UNL = 2.5 | L1 L1 FCZ = 200.0 || CB = 1.75 + FTZ = 200.0 || CMY = 0.85 | L1 L1 FCY = 200.0 || CMZ = 0.85 + L1 L1 FTY = 200.0 || FYLD = 300.0 | L0 fbz = 24.1 || NSF = 1.00 +---+---+---+---+---+---+---+---+---+---| fby = 101.4 || DFF = 0.0 -0.05 FV = 115.5 || dff = 0.0 ABSOLUTE MZ ENVELOPE fv = 6.0 || (WITH LOAD NO.) FT = 200.0 || fm = 146.3 || MAX FORCE/ MOMENT SUMMARY (KN-MET) Sx = 133.9 || ------------------------- Tou = 34.0 || || AXIAL SHEAR-Y SHEAR-Z MOMENT-Y MOMENT-Z || || VALUE -10.00 3.00 2.00 0.60 0.90 || LOCATION 0.000 0.000 0.000 0.000 0.000 || LOADING 1 1 1 1 1 || ||**************************************************************************||* *||* DESIGN SUMMARY (KN-MET) *||* -------------- *||* *|

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|* RESULT/ CRITICAL COND/ RATIO/ LOADING/ *|| FX MY MZ LOCATION || ====================================================== || PASS VON MISES 0.731 1 || 10.00 T 0.60 -0.90 0.000 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|

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Section 11

Mexican Codes

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11A.1 Design Operations

STAAD has the capabilities for performing concrete design. It will calculate thereinforcement needed for the specified concrete section. All the concrete designcalculations are based on the current: Complementary Technical Standards for theDesign and Construction of Concrete Structures – Nov. 1987. (Normas TécnicasComplementarias para Diseño y construcción de Estructuras de Concreto) of theMexican Construction Code for the Federal District –Aug. 1993 (Reglamento deConstrucciones para el Distrito Federal).

11A.2 Section Types for Concrete Design

The following types of cross sections can be defined for concrete design.

l Columns — Prismatic (Rectangular, Square, and Circular)

l Beams — Prismatic (Rectangular & Square), Trapezoidal, and T-shapes

l Walls — Finite element with a specified thickness

Figure 11.1 - Concrete shape nomenclature for beams and columns

11A.3 Member Dimensions

Concrete members which will be designed by the programmust have certainsection properties input under the  MEMBER PROPERTY command. The followingexample shows the required input:

UNIT CM

MEMBER PROPERTY

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13 TO 79 PRISM YD 40. ZD 20. IZ 53333 IY 13333

11 13 PR YD 20.

14 TO 16 PRIS YD 24. ZD 48. YB 18. ZB 12.

17 TO 19 PR YD 24. ZD 18. ZB 12.

In the above input, the first set of members are rectangular (40 cm depth and 20cm width) and the second set of members, with only depth and no width provided,will be assumed to be circular with 20 cm diameter. Note that no area (AX) isprovided for these members. For concrete design, this property must not beprovided. If shear areas and moments of inertias are not provided, the programcalculates these values from YD and ZD. Notice that in the above example the IZand IY values provided are actually 50% of the values calculated using YD and ZD.This is a conventional practice which takes into consideration revised sectionparameters due to cracking of section.

Note that the third and the fourth set of members in the above example representa T-shape and a TRAPEZOIDAL shape respectively. Depending on the properties(YD, ZD, YB, ZB, etc.) provided, the program will determine whether the section isrectangular, trapezoidal or T-shaped and the BEAM design will be doneaccordingly.

11A.4 Design Parameters

The program contains a number of parameters which are needed to performdesign by the Mexican code. Default parameter values have been selected suchthat they are frequently used numbers for conventional design requirements.These values may be changed to suit the particular design being performed. Table3.1 is a complete list of the available parameters and their default values.

The manual describes the commands required to provide these parameters in theinput file. For example, the values of SFACE and EFACE (parameters that are usedin shear design), the distances of the face of supports from the end nodes of abeam, are assigned values of zero by default but may be changed depending onthe actual situation. Similarly, beams and columns are designed for momentsdirectly obtained from the analyses without any magnification. The factors MMYand MMZ may be used for magnification of column moments. For beams, the usermay generate load cases which contain loads magnified by the appropriate loadfactors.

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Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Parameters

CODE - Must be specified as MEXICAN.

Design Code to follow.

See section 5.52.2 of the TechnicalReference Manual.

BTP 2 Bar type to use:

0. IMPERIAL (No 3 to 18)

1. METRIC (4.2 to 60mm)

2. MEXICAN (No 2 to 18)          

CCL 1 Concrete class according to 1.4.1d)to define Modulus of Elasticity

1. Class 1 Concrete

2. Class 2 Concrete

CFB FALSE Cold formed Bar classification todefine development multipliersaccording to table 3.1 NTC

l FALSE - Not cold formed bar

l TRUE - Cold formed bar

CLB 3 cm Clear cover for bottomreinforcement

CLS 3 cm Clear cover for side reinforcement

CLT 3 cm Clear cover for top reinforcement

DAG 2 cm Maximum diameter of aggregate, incurrent units.

Table 11A.1 - Mexican Concrete Design Parameters

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ParameterName

DefaultValue

Parameters

DCP TRUE Beam Loads and reactions in directcompression Cl-2.1.5.a.I  2ndparagraph

l FALSE - Loads applied indi-rectly

l TRUE - Direct compression

DEPTH YD Depth of concrete member, incurrent units. This value defaults toYD as provided under MEMBERPROPERTIES.

DIM TRUE l FALSE: Not precautions taken- Section reduction to section1.5 NTC Concrete

l TRUE: Precautions are takento assure dimensions

DSD TRUE Ductile frames in accordance withSection 5 of the code. Some designconditions are  considered (notincluding,  for the time being,geometric or confinement ones)

l FALSE - Non-Ductile frames

l TRUE - Ductile Frames

EFACE 0 Face to support location of end ofbeam. If specified, for shear forceat start is computed at a distance ofEFACE+d from the start joint of themember. Positive number.

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ParameterName

DefaultValue

Parameters

EXP FALSE Exposition to soil or weather todefine cover and min Steelreinforcement

l FALSE - Not exposed to soilor weather

l TRUE - Exposed to soil orweather

FC 200 Kg/cm2 Compressive Strength of Concrete

FYMAIN 4,200Kg/cm2

Yield Stress for main reinforcingsteel

FYSEC 4,200Kg/cm2

Yield Stress for secondary (stirrup)reinforcing steel

LSS 0 Part of the longitudinal steelconsidered to reduce shear. 0(zero) is conservative. Valuebetween 1 and 0.

LTC FALSE Light Concrete to definedevelopment multipliers accordingto table 3.1 NTC

l FALSE - Regular concrete

l TRUE - Lightweight concrete

MAXMAIN 12 Maximummain reinforcement barsize (Number 2 -18)

MINMAIN 2.5 Minimummain reinforcement barsize (Number 2 -18)

MINSEC 2.5 Minimum secondary reinforcementbar size (Number 2 -18)

MMY 1.0 Moment magnification factor for col-umns, about My.

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ParameterName

DefaultValue

Parameters

MMZ 1.0 Moment magnification factor for col-umns, about Mz.

MOE 198,000Kg/cm2

Concrete modulus of elasticiy.

NSECTION 12 Number of equally-spaced sectionsto be considered in finding criticalmoments for beam design

PHI 90 degrees Stirrups angle  with the axis of theelement

PSS TRUE Slab beared perimeter. To calculatemin steel required according to 2.1.2

REINF 0 Tied Column. A value of 1 willmean spiral.

SFACE 0 Face to support location of start ofbeam. If specified, for shear forceat start is computed at a distance ofSFACE+d from the start joint of themember. Positive number

TEQ FALSE Beam needed for torsionalequilibrium Cl.2.1.6a) 2ndparagraph

l FALSE - No

l TRUE - Yes

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ParameterName

DefaultValue

Parameters

TRACK 0 Beam Design

0. Critical Moment will not beprinted out with beam designreport.

1. Will mean a print out.

2. Will print out required steelareas for all intermediate sec-tions specified by NSECTION.

Column Design

0. Will print out detailed designresults.

1. Will mean a print out columninteration analysis results inaddition to TRACK 0 output.

2. will print out a schematic inter-action diagram and inter-mediate interaction values inaddition to all of the above.

WIDTH ZD Width of concrete member, incurrent units. This value defaults toZD as provided under MEMBERPROPERTIES

* These values must be provided in the current unit system being used.

Note: When using metric bars for design, provide values for these parametersin actual ‘mm‘ units instead of the bar number. The following metric bar sizesare available: 4.2mm, 6 mm, 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 32mm, 40 mm, 50 mm and 60 mm.

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11A.5 Beam Design

Beams are designed for flexure, shear and torsion. For all these forces, all activebeam loadings are prescanned to locate the possible critical sections. The totalnumber of sections considered is 12 (twelve) unless this number is redefined withan NSECTION parameter. All of these equally spaced sections are scanned todetermine moment and shear envelopes.

Design for Flexure

Reinforcement for positive and negative moments are calculated on the basis ofthe section properties provided by the user. If the section dimensions areinadequate to carry the applied load, that is if the required reinforcement is greaterthan the maximum allowable for the cross section, the program reports that beamfails in maximum reinforcement. Rectangular sections are also designed withcompression reinforcement.

Effective depth is chosen as Total depth - (Clear cover + diameter of stirrup + halfthe dia. of main reinforcement), and a trial value is obtained by adopting properbar sizes for the stirrups and main reinforcements. The relevant clauses in Sections1.5, 1.6, 2.1.1-2-5, 3.10 and 5.2.2 of NTC Concrete are utilized to obtain theactual amount of steel required as well as the maximum allowable and minimumrequired steel. These values are reported as ROW, ROWMX and ROWMN in theoutput and can be printed using the parameter TRACK 1.0 (see Table 11A.1). Inaddition, the maximum, minimum and actual bar spacing are also printed.

It is important to note that beams are designed for flexural moment MZ only. Themoment MY is not considered in the flexural design.

Design for Shear

Shear reinforcement is calculated to resist both shear forces and torsionalmoments. Shear forces are calculated at a distance (d+SFACE) and (d+EFACE)away from the end nodes of the beam. SFACE and EFACE have default values ofzero unless provided under parameters (see Table 11A.1). Note that the value ofthe effective depth "d" used for this purpose is the update value and accounts forthe actual c.g. of the main reinforcement calculated under flexural design. Clauses2.1.5-6 and 5.2.4 of NTC Concrete are used to calculate the reinforcement forshear forces and torsional moments. Based on the total stirrup reinforcementrequired, the size of bars, the spacing, the number of bars and the distance over

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which they are provided are calculated. Stirrups due to geometric conditions areassumed to be 2-legged, due to design conditions could be 2 or 4-legged.

Design for Anchorage

In the output for flexural design, the anchorage details are also provided. At anyparticular level, the START and END coordinates of the layout of the mainreinforcement is described along with the information whether anchorage in theform of a hook or continuation is required or not at these START and END points.Note that the coordinates of these START and END points are obtained after takinginto account the anchorage requirements. Anchorage length is calculated on thebasis of the Clauses described in Section 3.1 of NTC concrete. In case the programselects 2 different diameters for the main or compression reinforcement, only theanchorage for the largest diameter is analyzed.

Output

LevelSerial number of bar level which may contain one or more bar group

HeightHeight of bar level from the bottom of the beam

Bar InfoReinforcement bar information specifying number of bars and bar size

FromDistance from the start of the beam to the start of the reinforcement bar

ToDistance from the start of the beam to the end of the reinforcement bar

Anchor (STA/END)States whether anchorage, either hook or continuation, is needed at thestart (STA) or at the end (END).

RowActually required flexural reinforcement (As/bd) where b = width of crosssection (ZD for a rectangular or square section) and d = effective depth ofcross section (YD minus the distance from extreme tension fiber to the cen-troid of main reinforcement).

ROWMNMinimum required flexural reinforcement (Amin/bd)

ROWMX

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Maximum required flexural reinforcement (Amax/bd)

SpacingDistance between centers of adjacent bars of main reinforcement

VuFactored shear force at section

VcNominal shear strength provided by concrete

VsNominal shear strength provided by shear reinforcement

TuFactored torsional moment at section

TcNominal torsional moment strength provided by concrete

TsNominal torsional moment strength provided by torsion reinforcement

ACTUAL OUTPUT FROM DESIGN

==========================================-===========================

BEAM  NO.     1 DESIGN RESULTS - FLEXURE

PER CODE NTC FOR THE DESIGN AND CONSTRUCTION OFCONCRETE STRUCTURES,DDF

LEN -   525.00(cm)  FY -  4200.  FC -  250.  SIZE -   30.00 X   80.00(cm)

LEVEL    HEIGHT     BAR INFO       FROM          TO           ANCHOR

(cm)                     (cm)         (cm)         STA  END

_____________________________________________________________________

1          4.     8 - -NUM,  5      0.         39.        YES  NO

1          4.     1 - -NUM,  4      0.         39.               

2          8.     3 - -NUM,  5      0.         39.        YES  NO

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|----------------------------------------------------------------|

| CRITICAL     MOMENT=5978000.50 Kg cm   AT    0.00 (cm)LOAD    1|

| REQD STEEL=    24.41 (cm2)ROW=0.0109 ROWMX=0.0190

ROWMN=0.0026 |

| REQD COMP STEEL=     0.00 (cm2)                                |

| MAX/MIN/ACTUAL BAR SPACING=       24.14/  3.18/  3.45 (cm)     |

| COMP MAX/MIN/ACTUAL BAR SPACING=   0.00/  0.00/  0.00 (cm)     |

| BASIC/REQD. DEVELOPMENT LENGTH =    40.07/    39.08(cm)        |

|----------------------------------------------------------------|

Cracked Moment of Inertia Iz at above location =  1015658.4cm^4  

 3         77.    10 - -NUM,  4      0.         45.        YES  NO

 4         73.     9 - -NUM,  4      0.         45.        YES  NO

|----------------------------------------------------------------|

| CRITICAL     MOMENT=5978000.50 Kg cm   AT    0.00 (cm)LOAD    1|

| REQD STEEL=    24.17 (cm2)ROW=0.0107 ROWMX=0.0190

ROWMN=0.0026 |

| REQD COMP STEEL=     0.00 (cm2)                                |

| MAX/MIN/ACTUAL BAR SPACING=       24.46/  2.54/  2.72 (cm)     |

| COMP MAX/MIN/ACTUAL BAR SPACING=   0.00/  0.00/  0.00 (cm)     |

| BASIC/REQD. DEVELOPMENT LENGTH =    32.00/    44.81(cm)        |

|----------------------------------------------------------------|

Cracked Moment of Inertia Iz at above location =  1008728.7 cm^4  

REQUIRED REINF. STEEL SUMMARY :

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-------------------------------

SECTION     REINF STEEL(+VE/-VE)     MOMENTS(+VE/-VE)    LOAD(+VE/-

VE)

( CM )         (SQ.  CM )                (KG -CM  )

0.00      24.67/     24.67    5978000./  5978000.50      0/    0

525.00      24.67/     24.67    5978000./  5978000.50      0/    0

B E A M  N O.     1 D E S I G N  R E S U L T S – SHEAR

AT START SUPPORT - Vu=41850.00 Kg  Vc= 6074.49 Kg  Vs=44719.39

Kg

Tu=      0.00 Kg cm  Tc=      0.00 Kg cm  Ts=      0.00 Kg cm  LOAD   0

NO STIRRUPS ARE REQUIRED FOR TORSION.

REINFORCEMENT IS REQUIRED FOR SHEAR.

PROVIDE NUM. 2.5 2-LEGGED STIRRUPS AT   7.(cm)  C/C FOR  176.(cm)

ADDITIONAL LONGITUDINAL STEEL REQD. FOR TORSIONAL

RESISTANCE = 0.00   (cm2)

AT END   SUPPORT - Vu=37450.00 Kg  Vc= 6074.49 Kg  Vs=39219.39 Kg

Tu=      0.00 Kg cm  Tc=      0.00 Kg cm  Ts=      0.00 Kg cm  LOAD   0

NO STIRRUPS ARE REQUIRED FOR TORSION.

REINFORCEMENT IS REQUIRED FOR SHEAR.

PROVIDE NUM. 2.5 2-LEGGED STIRRUPS AT   8.(cm)  C/C FOR  176.(cm)

ADDITIONAL LONGITUDINAL STEEL REQD. FOR TORSIONAL

RESISTANCE =   0.00   (cm2)

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11A.6 Column Design

Columns design in STAAD per the Mexican code is performed for axial force anduniaxial as well as biaxial moments. All active loadings are checked to computereinforcement. The loading which produces the largest amount of reinforcement iscalled the critical load. Column design is done for square, rectangular and circularsections. For rectangular and circular sections, reinforcement is always assumed tobe equally distributed on all faces. This means that the total number of bars forthese sections will always be a multiple of four (4). If the MMAGx & -MMAGyparameters are specified, the column moments are multiplied by the correspondingMMAG value to arrive at the ultimate moments on the column. Minimum eccentricityconditions to be satisfied according to section 2.1.3.a are checked.

Method used: Bresler Load Contour Method

Known Values: Pu, Muy, Muz, B, D, Clear cover, Fc, Fy

Ultimate Strain for concrete : 0.003

Steps involved:

1. Assume some reinforcement. Minimum reinforcement (1% for ductile designor according to section 4.2.2 ) is a good amount to start with.

2. Find an approximate arrangement of bars for the assumed reinforcement.

3. Calculate PNMAX = Po, where Po is the maximum axial load capacity of thesection. Ensure that the actual nominal load on the column does not exceedPNMAX. If PNMAX is less than the axial force Pu/FR, (FR is the strengthreduction factor) increase the reinforcement and repeat steps 2 and 3. If thereinforcement exceeds 6% (or 4% for ductile design), the column cannot bedesigned with its current dimensions.

4. For the assumed reinforcement, bar arrangement and axial load, find theuniaxial moment capacities of the column for the Y and the Z axes,independently. These values are referred to as MYCAP and MZCAPrespectively.

5. Solve the Interaction Bresler equation:

(Mny/M

ycap)α + (M

nz/M

zcap)α

Where α = 1.24. If the column is subjected to uniaxial moment:  α = 1

6. If the Interaction equation is satisfied, find an arrangement with available bar

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sizes, find the uniaxial capacities and solve the interaction equation again. Ifthe equation is satisfied now, the reinforcement details are written to theoutput file.

7. If the interaction equation is not satisfied, the assumed reinforcement isincreased (ensuring that it is under 6% or 4% respectively)  and steps 2 to 6are repeated.

By the moment to check shear and torsion for columns the sections have to bechecked as beams and the most strict of both shear and torsion reinforcementadopted.

11A.7 Column Interaction

The column interaction values may be obtained by using the design parameterTRACK 1.0 or TRACK 2.0 for the column member. If a value of 2.0 is used for theTRACK parameter, 12 different Pn-Mn pairs, each representing a different point onthe Pn-Mn curve are printed. Each of these points represents one of the severalPn-Mn combinations that this column is capable of carrying about the given axis,for the actual reinforcement that the column has been designed for. In the case ofcircular columns, the values are for any of the radial axes. The values printed forthe TRACK 1.0 output are:

l P0          = Maximum allowable pure axial load on the column (momentzero).     

l Pnmax   = Maximum allowable axial load on the column.       

l P_bal     = Axial load capacity of balanced strain condition.       

l M_bal    = Uniaxial moment capacity of balanced strain condition.      

l E_bal     = M_bal / P_bal = Eccentricity of balanced strain condition.      

l M0         = Moment capacity at zero axial load.    

l P_tens    = Maximum permissible tensile load on the column.      

l Des. Pn  = Pu/FR where FR is the Strength Reduction Factor and Pu is theaxial load  for the critical load case.      

l Des.Mnx = Mux*MMAGx/FR where FR is the Strength Reduction Factor and Mu is  the  bending moment for the appropriate axis for the critical loadcase.  

l Mu  = Ö (Mux.Mmagx)²+ (Muy.Mmagy)²

l e/h          = (Mn/Pn)/h      where h is the length of the column

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11A.8 Column Design Output

The next table illustrates different levels of the column design output. 

The output is generated without any TRACK specification:

====================================================================

COLUMN  NO.     1  DESIGN PER  - AXIAL + BENDING

FY -4200.0  FC - 294.1 Kg/cm2  CIRC SIZE  100.0(cm)DIAMETER  

AREA OF STEEL REQUIRED = 128.506

BAR CONFIGURATION       REINF PCT.   LOAD   LOCATION   PHI

----------------------------------------------------------

46 - NUMBER  6           1.669        1      END     0.700

(EQUALLY SPACED)

TRACK=1 generates the following additional output:

COLUMN INTERACTION: MOMENT ABOUT Z/Y -AXIS (Kg-cm )

--------------------------------------------------------

P0          Pn max        P-bal.       M-bal.      e-bal.(cm)

2095196.38   2095196.38    727411.12  29235398.00      40.2

M0          P-tens.       Des.Pn      'Des.Mn     e/h

20606994.00   -550620.00         0.00  20000000.00     NaN

--------------------------------------------------------

TRACK=2 generates the following output in addition to all the above:

Pn          Mn          Pn          Mn

|             1934027.38  5373253.50   967013.69 27278232.00

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P0 |*            1772858.50 11408365.00   805844.75 28658428.00

| *           1611689.50 16296947.00   644675.81 29473708.00

Pn,max|__*          1450520.62 20083028.00   483506.84 28901764.00

|   *         1289351.62 23117562.00   322337.91 27205616.00

Pn    |    *        1128182.62 25462606.00   161168.95 24433192.00

NOMINAL|     *     

AXIAL|      *    

 COMPRESSION|       *   

Pb|-------*Mb 

|      *    

 ___________|____*_______

|  * M0   Mn,

| *   BENDING

P-tens|*     MOMENT

11A.9 Slab Design

Slabs are designed per Mexican NTC specifications. To design a slab, it must bemodeled using finite elements.

Element design will be performed only for the moments MX and MY at the center ofthe element. Design will not be performed for FX, FY, FXY,  MXY. Also, design isnot performed at any other point on the surface of the element. Shear is checkedwith Q.

A typical example of element design output is shown below. The reinforcementrequired to resist Mx moment is denoted as longitudinal reinforcement and thereinforcement required to resist My moment is denoted as transversereinforcement. The parameters FYMAIN, FC, CLB, CLS, CLT, DIM, and EXP listed inTable 11A.1 are relevant to slab design. Other parameters mentioned are not usedin slab design.

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Figure 11.2 - Element moments: Longitudinal (L) and Transverse (T)

ELEMENT DESIGN SUMMARY

----------------------

ELEMENT    LONG. REINF      MOM-X /LOAD    TRANS. REINF      MOM-Y

/LOAD

(SQ.CM/M )       (T -M /M )      (SQ.CM/M )       (T -M /M )

1 TOP : Longitudinal direction - Only minimum steel required.

1 BOTT: Transverse direction   - Only minimum steel required.

1 TOP :     2.239         0.00 /    0       3.252        983.00 /    1

BOTT:     3.758       983.00 /    1       1.684          0.00 /    0

1 SHEAR CAPACITY   3794.73 Kg ***PASS***

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Mexican Codes - Steel Design Per MexicanCode

11B.1 General

The program is based in: Complementary Technical Standards for the Design andConstruction of Steel Structures – Dec. 1987. (Normas Técnicas Complementariaspara Diseño y construcción de Estructuras Metálicas) of the Mexican ConstructionCode for the Federal District –Aug. 1993 (Reglamento de Construcciones para elDistrito Federal) (hereafter referred to as NTC 1987).

The design philosophy considered is that of  the  Load Cases and ResistanceMethod or Limit States Design usually known as Load and Resistance Factor Design(LRFD).

Structures are designed and proportioned taking into consideration the limit statesat which they would become unfit for their intended use. Two major categories oflimit-state are recognized--ultimate and serviceability. The primary considerationsin ultimate limit state design are strength and stability, while that in serviceability isdeflection. Appropriate load and resistance factors are used so that a uniformreliability is achieved for all steel structures under various loading conditions and atthe same time the chances of limits being surpassed are acceptably remote.

In the STAAD implementation of the Mexican Standards for steel structures,members are proportioned to resist the design loads without exceeding the limitstates of strength, and stability. It allows to check deformation to verifyserviceability.

Accordingly, the most economic section is selected on the basis of the least weightcriteria as augmented by the designer in specification of allowable member depths,desired section type, or other such parameters. The code checking portion of theprogram checks that main code requirements for each selected section are met andidentifies the governing criteria.

The following sections describe the salient features of the Mexican specifications asimplemented in STAAD steel design. A brief description of the fundamentalconcepts is presented here.

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11B.2 Limit States Design Fundamentals

The primary objective of the Limit States Design Specification is to provide auniform reliability for all steel structures under various loading conditions.

The Limit States Design Method uses separate factors for each load and resistance.Because the different factors reflect the degree of uncertainty of different loadsand combinations of loads and of the accuracy of predicted strength, a moreuniform reliability is possible.

The method may be summarized by the inequality

YiQi≤ R

nFR

On the left side of the inequality, the required strength is the summation of thevarious load effects, Q

i, multiplied by their respective load factors, Y

i. The design

strength, on the right side, is the nominal strength or resistance, Rn, multiplied by

a resistance factor, FR.

In the STAAD implementation of the Mexican Standards, it is assumed that theuser will use appropriate load factors and create the load combinations necessaryfor analysis. The design portion of the program will take into consideration theload effects (forces and moments) obtained from analysis. In calculation ofresistances of various elements (beams, columns etc.), resistance (nominalstrength) and applicable resistance factor will be automatically considered.

11B.3 Member End Forces and Moments

Member end forces and moments in the member result from loads applied to thestructure. These forces are in the local member coordinate system. the followingfigures show the member end actions with their directions. Refer to Section 1.19of the Technical Reference Manual for additional details.

11B.4 Section Classification

The Limit States Design specification allows inelastic deformation of sectionelements. Thus local buckling becomes an important criterion. Steel sections areclassified as compact (type 2), noncompact (type 3),  or slender element (type 4), sections depending upon their local buckling characteristics, besides sections type1 are able for plastic design. This classification is a function of the geometricproperties of the section. The design procedures are different depending on the

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section class. STAAD is capable of determining the section classification for thestandard shapes  and design accordingly. 

11B.5 Member in Axial Tension

The criteria governing the capacity of tension members is based on two limit states.The limit state of yielding in the gross section is intended to prevent excessiveelongation of the member. The second limit state involves fracture at the sectionwith the minimum effective net area. The net section area may be specified by theuser through the use of the parameter NSF (see Table 11B.1), that always refers tothe gross section. STAAD calculates the tension capacity of a given member basedon these two limit states and proceeds with member selection or code checkaccordingly. 

In addition to the tension resistance criterion, the user defines if tension membersare required to satisfy slenderness limitations which are a function of the nature ofuse of the member (main load resisting component, bracing member, etc.). In boththe member selection and code checking process, STAAD immediately does aslenderness check on appropriate members before continuing with otherprocedures for determining the adequacy of a given member.

11B.6 Axial Compression

The column strength equations take into account inelastic deformation and otherrecent research in column behavior. Two equations governing column strength areavailable, one for inelastic buckling and the other for elastic or Euler buckling. Bothequations include the effects of residual stresses and initial out-of-straightness.Compression strength for a particular member is calculated by STAAD according tothe procedure outlined in Section 3.2 of the NTC. For slender elements, theprocedure described in Section 2.3.6.NTC is also used.

The procedures of Section 3.2 of the Commentaries, design helps and examples ofthe Complementary Technical Standards for the Design and Construction of SteelStructures (de los Comentarios, ayudas de diseño y ejemplos de las NormasTécnicas Complementarias para el Diseño y Construcción de Estructuras Metálicas,DDF (Comentarios - Julio 1993) were implemented for the determination of designstrength for these limit states.

Effective length for calculation of compression resistance may be provided throughthe use of the parameters KY, KZ and/or LY, LZ. If not provided, the entire memberlength will be taken into consideration.

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In addition to the compression resistance criterion, compression members arerequired to satisfy slenderness limitations which are a function of the nature of useof the member (main load resisting component, bracing member, etc.). In both themember selection and code checking process, STAAD immediately does aslenderness check on appropriate members before continuing with otherprocedures for determining the adequacy of a given member.

11B.7 Flexural Design Strength

In the Limit States Design Method, the flexural design strength of a member isdetermined mainly by the limit state of lateral torsional buckling. Inelastic bendingis allowed and the basic measure of flexural capacity is the plastic moment capacityof the section.

The flexural resistance is a function of plastic moment capacity, actual laterallyunbraced length, limiting laterally unbraced length, buckling moment and thebending coefficient. The limiting laterally unbraced length Lu and flexuralresistance Mr are functions of the section geometry and are calculated as per theprocedure of Section 3.3.2 of the NTC.

The purpose of bending coefficient Cb is to account for the influence of themoment gradient on lateral-torsional buckling. This coefficient can be specified bythe user through the use of parameter CB or CBy (see Table 11B.1) or may becalculated by the program (according to LRDF USA specification) if CB is specifiedas 0.0. In the absence of the parameter CB, a default value of 1.0 will be used.

To specify laterally unsupported length, either of the parameters UNL and UNF(see Table 10B.1) can be used.

It is taken into account the reduction of flexural resistance due to slender webaccording to section 4.5.8 of the NTC

For the sections where the web and flange are slender the LRDF USA specificationwas used.

Stress areas due to bending about y axis  (MY)

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Note: The local X axis goes into the page; the Global Y axis is vertical upwards;the shaded area indicates area under compression; the area not shadedindicates area under tension.

Stress areas due to bending about Z axis (MZ)

11B.8 Design for Shear

The procedure of Sect. 3.3.3 of the NTC is used in STAAD to design for shear forcesin members. Besides combined bending and shear is checked according to section3.3.4 of the NTC, considering also the limits for stiffeners of the web according tosections 4.5.6/7 of the NTC. Shear in wide flanges and channel sections is resistedby the area of the web/s..

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11B.9 Combined Compression Axial Force andBending

The interaction of flexure and axial forces in singly and doubly symmetric shapes isgoverned by formulas of the Section 3.4 of the NTC. These interaction formulascover the general case of biaxial bending combined with axial force. They are alsovalid for uniaxial bending and axial force.

It is considered that the frames are part of structures that have shear walls or rigidelements so that the lateral displacements of a floor could be disregarded. Theprogram has included formulas to include structures with lateral displacements inthe future considering for B2 the columns individually and not the complete flooranalysis.

It is taken into account if the elements have transverse loads and if the ends areangularly restrained.

11B.10 Combined Tension Axial Force and Bending

Based on Section 3.5 4 of the NTC.

11B.11 Design Parameters

Design per Mexican Standards is requested by using the CODE. Other applicableparameters are summarized in Table 11B.1 below. These parameters communicatedesign decisions from the engineer to the program and thus allow the engineer tocontrol the design process to suit an application's specific needs.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements, some or all of these parameter values may be changed to exactlymodel the physical structure.

The parameters DMAX and DMIN may only be used for member selection only.

Once a parameter is specified, its value stays at that specified number till it isspecified again. This is the way STAAD works for all codes.

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ParameterName

Default Value Description

CODE - Must be specified as MEXICAN.

Design Code to follow.

See section 5.48.1 of theTechnical Reference Manual.

KX 1.0  K value for  flexural-torsionalbuckling

KY 1.0  K value in local Y axis- Usuallyminor axis

KZ 1.0  K value in local Z axis- Usuallymajor axis

LX Member length Length for  flexural-torsionalbuckling

LY Member length Length to calculateslenderness ratio for bucklingabout  local Y axis.

LZ Member length Length to calculateslenderness ratio for bucklingabout  local Z axis.

FYLD 2530 kg/cm2 Minimum Yield strength ofsteel

FU 4230 Kg/cm2 Ultimate tensile strength ofsteel

NSF 1 Net section factor for tensionmembers

UNT Member length Unsupported length (L) of thetop* flange for calculatingflexural strength . Will be usedonly if  compression is in thetop flange.

Table 11B.1 - Design Parameters According to Mexican NTC Stand-ards - Steel

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ParameterName

Default Value Description

UNB Member length Unsupported length (L) of thebottom* flange for calculatingflexural strength . Will be usedonly if  compression is in thebottom flange.

STIFF Member length Spacing of stiffeners for beamsfor shear design

Cb y Cby 1 Coefficient C defined persection 3.3.2.2. If Cb is set to 0.0 it will be calculated by theprogram according to  LRFDUSA (CbMex=1/CbUSA). Anyother value will be directlyused in the design.

TRACK 0 0 = Suppress all designstrengths 

1 =  Print all design strengths 

2 = Print expanded designoutput

DMAX 114 cm Maximum allowable depth

DMIN 0.0 cm Minimum allowable depth

RATIO 1.0 Permissible ratio of actual loadeffect and design strength

BEAM 0 0: Design at ends and thoselocations specified by SECTION  command.

1: Design at ends  and atevery  y cada 1/12th pointalong member length

 Rigid_to_H_Loads

TRUE                   Defines if the structure has elements to bear the wind load

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ParameterName

Default Value Description

( shear walls, wind trusses orbracing rigid elements ) thatrestrict lateral displacementsand allow to disregardslenderness effects.

IRREG 0 Variable defined for the wholestructure indicating if it  isregular or irregular accordingto section 3.4 of the NTC.

IRREG=1 for  columns being part of irregular structures.

I_NO_OXIG 0 Defined for  I  shapes or tubes 

Curve Definition according to NTC.3.2.2.1a) 

I_NO_OXIG.= 0  impliesn=1.4

laminated I shapes, tubes orbuilt up with 3 or 4 weldedplates obtained from widerplates cuts with oxygen.

I_NO_OXIG.= 1  implies n=1 

I shapes, tubes or built up with3 or 4 welded plates 

n is defined by the program 

IMAIN_MEM 0 IMAIN_MEM=0 MAINMEMBER 

IMAIN_MEM=1  Secondaryand wind trusses

Ccomb 1 Cfactor for combined forceswhen there are transverse

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ParameterName

Default Value Description

loads in the members. Section3.4.3.3.ii NTC

Ccomb=1 If members ends arerestricted angularly.

Ccomb=0.85 If members ends

are not restricted angularly.           DUCTILE_SEISMIC _DESIGN

TRUE DUCTILE FRAMESACCORDING TO SECTION 11.Main design conditions are considered (not including, atthe moment, geometric  ones)

KX 1.0  K value for  flexural-torsionalbuckling

KY 1.0  K value in local Y axis- Usuallyminor axis

KZ 1.0  K value in local Z axis- Usuallymajor axis

LX Member length Length for  flexural-torsionalbuckling

LY Member length Length to calculateslenderness ratio for bucklingabout  local Y axis.

LZ Member length Length to calculateslenderness ratio for bucklingabout  local Z axis.

FYLD 2530 kg/cm2 Minimum Yield strength ofsteel

FU 4230 Kg/cm2 Ultimate tensile strength ofsteel

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ParameterName

Default Value Description

NSF 1 Net section factor for tensionmembers

UNT Member length Unsupported length (L) of thetop* flange for calculatingflexural strength . Will be usedonly if  compression is in thetop flange.

UNB Member length Unsupported length (L) of thebottom* flange for calculatingflexural strength . Will be usedonly if  compression is in thebottom flange.

STIFF Member length Spacing of stiffeners for beamsfor shear design

Cb y Cby 1 Coefficient C defined persection 3.3.2.2. If Cb is set to 0.0 it will be calculated by theprogram according to  LRFDUSA (CbMex=1/CbUSA). Anyother value will be directly

used in the design.                                              

TRACK 0 0 = Supress all designstrengths                                

1 =  Print all design strengths                                  

2 = Print expanded designoutput

DMAX 114 cm Maximum allowable depth

DMIN 0.0 cm Minimum allowable depth

RATIO 1.0 Permissible ratio of actual loadeffect and design strength

BEAM 0 0: Design at ends and thoselocations specified by 

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ParameterName

Default Value Description

SECTION  command.                                               

1: Design at ends  and atevery  y cada 1/12th pointalong member length

 Rigid_to_H_Loads

TRUE                   Defines if the structure has elements to bear the wind load( shear walls, wind trusses orbracing rigid elements ) thatrestrict lateral displacementsand allow to disregardslenderness effects.

IRREG 0 Variable defined for the wholestructure indicating if it  isregular or irregular accordingto section 3.4 of the NTC.

IRREG=1 for  columns being part of irregular structures.

I_NO_OXIG 0 Defined for  I  shapes or tubes                                

Curve Definition according to NTC.3.2.2.1a) 

I_NO_OXIG.= 0  impliesn=1.4                                                  

laminated I shapes, tubes orbuilt up with 3 or 4 weldedplates obtained from wider

plates cuts with oxygen.                                                                

I_NO_OXIG.= 1  implies n=1                                                     

I shapes, tubes or built up with

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ParameterName

Default Value Description

3 or 4 welded plates     

n is defined by the program                                                

IMAIN_MEM 0 IMAIN_MEM=0 MAINMEMBER                              

IMAIN_MEM=1  Secondaryand wind trusses

Ccomb 1 Cfactor for combined forceswhen there are transverseloads in the members. Section3.4.3.3.ii NTC

Ccomb=1 If members ends arerestricted angularly.  

Ccomb=0.85 If members ends

are not restricted angularly.           DUCTILE_SEISMIC _DESIGN

TRUE DUCTILE FRAMESACCORDING TO SECTION 11.Main design conditions are considered (not including, atthe moment, geometric  ones)

* Top and Bottom represent the positive and negative side of the local Y axis (localZ axis if  SET Z UP  is used.

For deflection check, parameters DFF, DJ1 and DJ2 from Table 2.1 may be used. Allrequirements remain the same.

11B.12 Code Checking and Member Selection

Both code checking and member selection options are available in STAAD MexicanStandards implementation.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

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Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

11B.13 Tabulated Results of Steel Design

Results of code checking and member selection are presented in a tabular format.

CRITICAL COND refers to the section of the Mexican NTC which governed thedesign.

If the TRACK is set to 1.0, member design strengths will be printed out.

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Section 12

Russian Codes

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Russian Codes - Concrete Design Per RussianCode (SNiP 2.03.01-84*)

12A.1 General

Russian Code SNiP 2.03.01–84* “Plain concrete and concrete structures” is basedon the method of limit states. Code SNiP 2.03.01–84* defines two groups of limitstates.

Analysis according to the first group of limit states is performed to avoid thefollowing phenomena:

l brittle, plastic or other type of failure,

l loss by structure of stable form or position,

l fatigue failure,

l failure due to the action of load actions and unfavorable environmentaleffects.

Analysis according to the second group of limit states is performed to avoid thefollowing phenomena:

l excessive and long-term opening of cracks if they are allowed according toservice conditions,

l excessive displacements.

Analysis of structures for the first group of limit states is performed with the use ofthe maximum (design) loads and actions. Analysis of structures for the secondgroup of limit states is made in accordance with the operational (normative) loadsand actions. Ratio between design and normative loads is called reliabilitycoefficient for loads which is determined according to SNiP 2.01.07.-85 “Loads andactions”.

Reliability coefficient γnfor destination according to SNiP 2.01.07.-85 shall be

considered in determination of loads and their combinations.

Program STAAD.Pro makes it possible to calculate reinforcement for concretemembers according to codes of many countries round the World and Russian CodeSNiP 2.03.01-84* inclusive. Algorithms for calculation of reinforcement of concretelinear (beams, columns) and 2D (two dimensional) (slabs, walls, shells) members

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are incorporated in program STAAD.Pro. Not only Code SNiP 2.03.01-84* butalso the “Guide for design of plain concrete and reinforced concrete structuresfrom normal weight and lightweight concrete (to SNiP 2.03.01-84)” have beenused in creation of these algorithms.

It is possible using program STAAD.Pro to calculate reinforcement for beams ofrectangular or T section and for columns of rectangular or circular section (Fig.1).

Figure 12A.1 - Notation of dimensions for rectangular, circular and T sections

Flange of T-shape beams may be situated at the top zone of the section if the angleBETA=0°, or at the bottom zone of the section, if BETA=180°.

12A.2 Design Parameters and Input Data

Entry of data of cross-sections of beams and columns is made by the use ofMEMBER PROPERTIES command, and thicknesses of 2D members are enteredby ELEMENT PROPERTY command.

Example:

UNIT MM

MEMBER PROPERTIES

* COLUMNSOF RECTANGULAR CROSS-SECTION

1 TO 16 PRI YD 350. ZD 350.

* COLUMNSOF CIRCULAR CROSS-SECTION

17 TO 22 PRI YD 350.

* BEAMSOF T CROSS-SECTION

23 TO 40 PRI YD 450. ZD 550. YB 230. ZB 200.

UNIT METER

ELEMENT PROPERTY

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41 TO 100 THICKNESS 0.14

101 TO 252 THICKNESS 0.16

* FLANGEOF T BEAMS IS LOCATED AT THE BOTTOMZONEOFCROSS-SECTION

BETA 180. MEMB 23 TO 40

COMMANDS FOR CALCULATION OF REINFORCEMENT ARELOCATED IN THE INPUT DATA FILE AFTER THE COMMAND OFANALYSIS AND AS A RULE, AFTER OUTPUT COMMANDS TOPRINTRESULTS OF CALCULATION.

Example:

*  COMMAND OF ANALYSIS

PERFORM ANALYSIS

.

.* OUTPUT COMMAND TOPRINT RESULTS OF CALCULATION(ACCORDING TOUSER’S JUDGMENT)

.

* COMMAND OF LOADING AND THEIR COMBINATIONSCONSIDERED IN DESIGN

LOAD LIST 1 5 TO 9

* COMMAND TOSTART REINFORCEMENT CALCULATIONPROCEDURE

START CONCRETE DESIGN

CODE RUSSIAN

.* LIST OF PARAMETERS BEING USED IN REINFORCEMENTCALCULATION

.

.

BCL 20. MEMB 17 TO 22 

CL1 0.04 MEMB 1 TO 40

DD2 10. MEMB 23 TO 40

CRA 0.036 MEMB 41 TO 252

.

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.

.

* COMMAND OF BEAMREINFORCEMENT CALCULATION

DESIGN BEAM 23 TO 40

* COMMAND OF COLUMN REINFORCEMENT CALCULATION

DESIGN COLUMN 1 TO 22

* COMMAND OF CALCULATION 2D ELEMENTS (SLABS,WALLS,SHELLS)

DESIGN ELEMENT 41 TO 252

* COMMAND OF INTERRUPTION REINFORCEMENTCALCULATION

END CONCRETE DESIGN

In tables 1, 2 and 3 information about parameters used for calculation ofreinforcement for beams, columns and 2D (two dimensional) members ispresented. Values of parameters do not depend on UNIT command. In the file ofinput data only such parameters have to be taken, the values of which differ fromdetermined in the program.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

No. Parametername

DefaultValue

Description

1 NLT 1 Number of long-term loading case

2 RCL 3 Class of longitudinalreinforcement:

l RCL = 1, if class ofreinforcement is A-I;

l RCL = 2, if class ofreinforcement is A-II;

l RCL = 3, if class of

Table 12A.1 - Names of parameters for Concrete design accordingto Russian Code -СНиП 2.03.01-84* for beams.

688— STAAD.Pro

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No. Parametername

DefaultValue

Description

reinforcement is A-III;

l RCL = 33, if class ofreinforcement is A-IIIb;

l RCL = 4, if class ofreinforcement is A-IV;

l RCL = 5, if class ofreinforcement is A-V;

l RCL = 6, if class ofreinforcement is A-VI;

l RCL = 7, if class ofreinforcement is A-VII;

l RCL = 77, if class ofreinforcement is K-7;

l RCL = 8, if class ofreinforcement is B-II;

l RCL = 9, if class ofreinforcement is Bp-II;

l RCL = 10, if class ofreinforcement is Bp-I;

l RCL = 19, if class ofreinforcement is K-19

2 RCL 3 Class of longitudinalreinforcement: Russian Grade:

l 1 = A240;

l 2 = A300;

l 3 = A400;

l 4 = A500;

l 5 = B500;

l 6 = A500SP;

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No. Parametername

DefaultValue

Description

European Grade:

l 11 = S240;

l 12 = S400;

l 13 = S500;

3 USM 1. Total product of service conditionscoefficients for longitudinalreinforcement (g

s)

4 UB2 0.9 Specific service conditionscoefficient for concrete (g

b2)

5 DD1 16. Diameter of longitudinalreinforcement bars in beam tensionzone

6 DD2 16. Diameter of shear reinforcementbars for beam;

7 BCL 15. Compression class of concrete

7 BCL 15. Compression Class of concrete.

l 10 = B10;

l 15 = B15

l 20 = B20;

l 25 = B25;

l 30 = B30;

l 35 = B35;

l 40 = B40;

l 45 = B45;

l 50 = B50;

l 55 = B55;

l 60 = B60;

l 8.10 = C8/10

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No. Parametername

DefaultValue

Description

l 12.15 = C12/15;

l 16.20 = C16/20

l 25.30 = C25/30 

l 30.37 = C30/37

l 35.45 = C35/45

l 40.50 = C50/50

l 45.55 = C45/55

l 50.60 = C50/60

l 60.75 = C60/75

l 70.85 = C70/85

l 80.95 = C80/95

l 90.105 = C90/105

8 UBM 1. Product of service conditionscoefficients for concrete, exceptUB2 (g

b)

9 TEM 0. Parameter of concrete hardeningconditions:

l TEM=0, for naturalhardening conditions;

l TEM=1, for steam hardeningconditions

10 CL1 0.05 Distance from top/bottom fiber ofbeam cross section to the center oflongitudinal reinforcement bar;

11 CL2 0.05 Distance from left/right side ofbeam cross section to the center oflongitudinal reinforcement bar

12 WST 0.4 Ultimate width of short-term crack

13 WLT 0.3 Ultimate width of long-term crack

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No. Parametername

DefaultValue

Description

14 SSE 0 Limit state parameter for beamdesign

l SSE=0, if calculation ofreinforcement amount mustbe carried out according tothe requirements of loadcarrying capacity (the firstlimit state);

l SSE=1, if calculation ofreinforcement amount mustbe carried out according tothe cracking requirements(the second limit state)

15 RSH 1 Class of shear reinforcement:

l RSH = 1, if class ofreinforcement is A-I;

l RSH = 2, if class ofreinforcement is A-II;

l RSH = 3, if class ofreinforcement is A-III;

l RSH = 33, if class ofreinforcement is A-IIIb;

l RSH = 4, if class ofreinforcement is A-IV;

l RSH = 5, if class ofreinforcement is A-V;

l RSH = 6, if class ofreinforcement is A-VI;

l RSH = 7, if class ofreinforcement is A-VII;

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No. Parametername

DefaultValue

Description

l RSH = 77, if class ofreinforcement is K-7;

l RSH = 8, if class ofreinforcement is B-II;

l RSH = 9, if class ofreinforcement is Bp-II;

l RSH = 10, if class ofreinforcement is Bp-I;

l RSH = 19, if class ofreinforcement is K-19

15 RSH 1 Class of shear reinforcement:

Russian Grade:

l 1 = A240;

l 2 = A300;

l 3 = A400;

l 4 = A500;

l 5 = B500;

l 6 = A500SP;

European grade:

l 11 = S240;

l 12 = S400;

l 13 = S500;

16 FWT ZD Design width of beam top flange.Use for beam design only withdefault value provided as ZD inmember properties.

17 FWB ZB Design width of beam bottomflange. Use for beam design onlywith default value provided as ZB

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No. Parametername

DefaultValue

Description

in member properties.

18 DEP YD Design depth of beam section. Usefor beam design only with defaultvalue provided as YD in memberproperties.

19 SFA 0. Face of support location at the startof the beam. Use for beam designonly.

20 EFA 0. Face of support location at the endof the beam. Use for beam designonly.

21 NSE 13 Number of equally-spaced sectionsfor beam design. Use for beamdesign only. Upper limit is equal to20.

No. ParameterName

DefaultValue

Description

1 NLT 1 Number of long-term loading case

2 RCL 3 Class of longitudinalreinforcement:

Russian Grade:

l 1 = A240;

l 2 = A300;

l 3 = A400;

l 4 = A500;

l 5 = B500;

l 6 = A500SP;

European Grade:

Table 12A.2 - Names of parameters for Concrete design accordingto Russian Code СНиП 2.03.01-84* for columns

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Page 705: International Codes v8i

No. ParameterName

DefaultValue

Description

l 11 = S240;

l 12 = S400;

l 13 = S500;

3 USM 1. Total product of service conditionscoefficients for longitudinalreinforcement (g

s)

4 UB2 0.9 Specific service conditionscoefficient for concrete (g

b2)

5 DD1 16. Minimum diameter of longitudinalreinforcement bars for column

6 DD2 16. Maximum diameter of longitudinalreinforcement bars for column

7 BCL 15. Compression class of concrete:

l 10 = B10;

l 15 = B15

l 20 = B20;

l 25 = B25;

l 30 = B30;

l 35 = B35;

l 40 = B40;

l 45 = B45;

l 50 = B50;

l 55 = B55;

l 60 = B60;

l 8.10 = C8/10

l 12.15 = C12/15;

l 16.20 = C16/20

l 25.30 = C25/30

International Design Codes Manual — 695

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No. ParameterName

DefaultValue

Description

l 30.37 = C30/37

l 35.45 = C35/45

l 40.50 = C50/50

l 45.55 = C45/55

l 50.60 = C50/60

l 60.75 = C60/75

l 70.85 = C70/85

l 80.95 = C80/95

l 90.105 = C90/105

8 UBM 1. Product of service conditionscoefficients for concrete, exceptUB2 (g

b)

9 TEM 0. Parameter of concrete hardeningconditions:

l TEM=0, for naturalhardening conditions;

l TEM=1, for steam hardeningconditions

10 CL1 0.05 Distance from edge of columncross section to the center oflongitudinal reinforcement bar

11 ELY 1. Column's length coefficient toevaluate slenderness effect in localY axis

12 ELZ 1. Column's length coefficient toevaluate slenderness effect in localZ axis

13 RSH 1. Class of shear reinforcement:

Russian Grade:

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Page 707: International Codes v8i

No. ParameterName

DefaultValue

Description

l 1 = A240;

l 2 = A300;

l 3 = A400;

l 4 = A500;

l 5 = B500;

l 6 = A500SP;

European grade:

l 11 = S240;

l 12 = S400;

l 13 = S500;

No. ParameterName

DefaultValue

Description

1 NLT 1 Number of long-term loading case

2 RCL 3 Class of longitudinal reinforcement:

Russian Grade:

l 1 = A240;

l 2 = A300;

l 3 = A400;

l 4 = A500;

l 5 = B500;

l 6 = A500SP;

European Grade:

l 11 = S240;

l 12 = S400;

Table 12A.3 - Names of parameters for Concrete design accordingto Russian Code (SNiP 2.03.01-84*) for slabs and/or walls

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No. ParameterName

DefaultValue

Description

l 13 = S500;

3 USM 1. Total product of service conditionscoefficients for longitudinalreinforcement (g

s)

4 UB2 0.9 Specific service conditionscoefficient for concrete (g

b2)

5 SDX 16. Diameter of reinforcing bars locatedin the first local (X) direction ofslab/wall

6 SDY 16. Diameter of reinforcing bars locatedin the second local (Y) direction ofslab/wall

7 BCL 15. Compression class of concrete:

l 10 = B10;

l 15 = B15

l 20 = B20;

l 25 = B25;

l 30 = B30;

l 35 = B35;

l 40 = B40;

l 45 = B45;

l 50 = B50;

l 55 = B55;

l 60 = B60;

l 8.10 = C8/10

l 12.15 = C12/15;

l 16.20 = C16/20

l 25.30 = C25/30

l 30.37 = C30/37

698— STAAD.Pro

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Page 709: International Codes v8i

No. ParameterName

DefaultValue

Description

l 35.45 = C35/45

l 40.50 = C50/50

l 45.55 = C45/55

l 50.60 = C50/60

l 60.75 = C60/75

l 70.85 = C70/85

l 80.95 = C80/95

l 90.105 = C90/105

8 UBM 1. Product of service conditionscoefficients for concrete, exceptUB2 (g

b)

9 TEM 0. Parameter of concrete hardeningconditions:

l TEM=0, for natural hardeningconditions;

l TEM=1, for steam hardeningconditions

10 CL 0.05 Distance from top/bottom face ofslab/wall element to the center oflongitudinal reinforcing barslocated in first local (X) direction.(Main thickness of top/bottomconcrete cover for slab/wallelement)

11 CRA 0.05 Distance from top/bottom face ofslab/wall element to the center oftransverse reinforcing bars locatedin second local (Y) direction(Secondary thickness of top/bottomconcrete cover for slab/wall)

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No. ParameterName

DefaultValue

Description

12 WST 0.4 Ultimate width of short-term crack

13 WLT 0.3 Ultimate width of long-term crack

14 STA 0 Parameter of limit state forslab/wall design:

l STA=0, if calculation ofnonsymmetricalreinforcement must be carriedout according to therequirements of load carryingcapacity (the first limit state);

l STA=1, if calculation ofsymmetrical reinforcementmust be carried out accordingto the requirements of loadcarrying capacity (the firstlimit state);

l STA=2, if calculation ofnonsymmetricalreinforcement must be carriedaccording to the crackingrequirements (the secondlimit state);

l STA=3, if calculation ofsymmetrical reinforcementmust be carried according tothe cracking requirements(the second limit state)

15 SELX 0. Design length of wall member toevaluate slenderness effect in localX axis

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Page 711: International Codes v8i

No. ParameterName

DefaultValue

Description

16 SELY 0. Design length of wall member toevaluate slenderness effect in localY axis

17 MMA 0 Design parameter of slab/wallreinforcement:

l MMA=0, if reinforcementcalculation must be applied bystresses in local axis;

l MMA=1, if reinforcementcalculation must be applied byprincipal stresses

18 MMB 1 Design parameter of slab/wallreinforcement:

l MMB=0, if the effect ofadditional eccentricity is nottaken into account;

l MMB=1, if the effect ofadditional eccentricity is takeninto account

19 RSH 1. Class of shear reinforcement:

Russian Grade:

l 1 = A240;

l 2 = A300;

l 3 = A400;

l 4 = A500;

l 5 = B500;

l 6 = A500SP;

European grade:

l 11 = S240;

International Design Codes Manual — 701

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No. ParameterName

DefaultValue

Description

l 12 = S400;

l 13 = S500;

12A.3 Beams

Reinforcement for beams of rectangular and T cross-section can be calculated. In

calculation of longitudinal reinforcement bending moment about local axis and torsional moments are considered, but influence of longitudinal forces andbending moments in relation to local axis  is ignored. In calculation oftransverse reinforcement shear forces parallel to local axis and torsionalmoments are taken into account.

Reinforcement for beams can be calculated either from conditions of strength orfrom conditions of open crack width limitation (see parameter SSE).

Parameters SFA and ЕFA are considered only in calculation of transversereinforcement.

In general case calculation of reinforcement for beams is carried out two times –according to strength conditions and according to conditions of open crack widthlimitation. In reinforcement calculations from conditions of strength design valuesof load have to be taken and in calculations from conditions of crack widthlimitation – characteristic (normative) load values are used. Both calculations canbe carried out in one session with the use multiple analysis possibility of theprogram STAAD.Pro.

In most cases calculation of reinforcement is carried out with account only of apart of loadings. In such cases command LOAD LIST is used, in which numbersof loads considered in calculation are indicated. Number of permanent and long-term loads equal to parameter NLT must be included into the list of consideredloads.

It has to be noted, that values of parameters DD1 and DD2 have influence notonly on the width of opened crack but also in some cases, on design andnormative reinforcement resistances.

Parameter BCL can be equal to any value of concrete compression strength classgiven in SNiP 2.03.01-84* and to any intermediate value as well.

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Page 713: International Codes v8i

It should be remembered, that accuracy of results of calculation of transversereinforcement increases with the value of parameter NSE.

Parameters SFA and ЕFA are considered only in calculations of transversereinforcement. Beam 1 is shown in Figure 2 with rigid intervals the lengths of whichare: at the start of the beam 0.3m and at the end – 0.2m. In modeling of the beamthe following command can be used.

MEMBEROFFSET

1 START 0.3 0 0

1 END -0.2 0 0

Figure 12A.2 - Diagram of a beam with rigid intervals

When commandMEMBER OFFSET is used forces corresponding to the beam thelength of which is equal to the distance between points a and b are calculated andthen used in calculation of reinforcement. In such case it is necessary to take intoaccount default values of parameters SFA and ЕFA equal to zero.

When commandMEMBER OFFSET is not used forces corresponding to the beamthe length of which is equal to the distance between points 10 and 11 are calculatedand then used in calculation of reinforcement. In this case it is necessary toconsider values of parameters SFA=0.3 and ЕFA=0,2 in reinforcementcalculation.

In both cases calculated quantity of transverse reinforcement will be the same.Calculated quantity of longitudinal reinforcement in the second case will be greater.

For beam the following output is generated:

l beam number;

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l method of calculation (according to conditions of strength or limitations ofopened crack width);

l length and cross-sectional dimensions;

l distance from resultant of forces acting in bottom/top reinforcement tobottom/top edge of the section;

l distance from the side edge of cross-section of the beam web to thecentroid of longitudinal bars located at this edge;

l concrete class;

l class of longitudinal and transverse reinforcement;

l assumed in calculations bar diameters of longitudinal and transversereinforcement;

l calculation results of longitudinal and transverse reinforcement (in twotables).

In nine columns of the first table the following results are presented:

Result Description

Section distance of the section from the “start” of the beam, мм

As- cross-sectional area of longitudinal reinforcement in the bottom zone of

cross-section of the beam, if angle BETA=0°, or in the top zone, ifBETA=180° , sq.cm

As+ cross-sectional area of longitudinal reinforcement in the top zone of

cross-section of the beam , if angle BETA=0°, or in the top zone, ifBETA=180° , sq.cm

Moments (-/+) values of bending moments, determining cross-sectional areas of

longitudinal reinforcement As-  and As+ , kNm

Load. N. (-/+) numbers of loading versions, determining cross-sectional areas of

longitudinal reinforcement

Acrc1 short-term opened crack width*, mm

Acrc2 long-term opened crack width*, mm

Table 12A.4 - Beam design output 1

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Page 715: International Codes v8i

* Opened crack width is presented only in the case when calculation is performedaccording to conditions limiting opened crack width.

In ten columns of second table the following results are presented:

Result Description

Section distance of the section from the “start” of the beam, mm

Qsw intensity of transverse reinforcement, kN/m

Asw cross-sectional area of transverse bars, sq.cm, if their step is 10, 15, 20,25 or 30 cm

Q value of shear force parallel to the local axis, kN

T value of  torsional moment, kNm

Load N. number of loading version, determining intensity of transverse

reinforcement

Table 12A.5 - Beam design output 2

An example of output of calculation results is presented below.

BEAM NO. 23 DESIGN RESULTS

(by limitation of crack width)

Length - 6000 mm.

Section: BF1= 550 mm,  B= 200 mm, HF1=220 mm, H=450 mm.

Distance from top/bottom surface of beam to center of longitudinal

reinforcement - 40 mm.

Distance from side surface of beam to center of longitudinal

reinforcement - 30 mm.

Concrete class - В25.0 (Rb=13.05 MPa; Rbt=0.94 MPa; Gb2=0.9).

Class of longitudinal reinforcement - А-III (Rs=365.0 MPa; Rsc=365.0 MPa).

Diameter of longitudinal reinforcement bars D=16 mm.

Class of shear reinforcement - А-I (Rsw=175.0 MPa).

Diameter of shear reinforcement bars Dw=10 mm.

L O N G I T U D I N A L   R E I N F O R C E M E N T

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Section   As-As+  Moments(-/+) Load.N.(-/+)     Acrc1  Acrc2   

mm       sq.cm    kNm                       mm     mm

---------------------------------------------------------------------

     0.    10.92 0.41 -152. /      2. 6 /    40.237 0.121

    500. 4.74 0.41 -60. /      0. 5 /    00.294 0.157

1000.    1.13 1.13 -5. /     17. 4 /    60.000 0.000

1500.    1.13 6.41 -8. /     75. 4 /    60.295 0.147

2000. 1.13 9.24 -11. /    115. 4 /    60.298 0.149

2500. 1.13  11.53 -14. /    139. 4 /    60.271 0.134

3000. 1.19  12.16 -18. /    144. 4 /    60.263 0.127

3500. 1.41  10.86 -21. /    132. 4 /    60.277 0.130

4000. 1.63 8.28 -24. /    103. 4 /    60.296 0.129

4500. 1.95 4.54 -27. /      56. 4 /    60.299 0.093

5000. 3.23 0.58 -39. /        9. 5 /    30.293 0.157

5500. 0.74 0.41 -

124.

/        0. 5 /    00.271 0.142

6000. 16.89 0.41 -

226.

/        0. 5 /    00.155 0.078

S H E A R   R E I N F O R C E M E N T

Section  Qsw         Asw, cm^2, if Sw=     Q   T   Load 

mm      kN/m    10cm  15cm   20cm  25cm  30cm   kN    kNm  N.

0. 251.3 1.44

 2.15 2.87

3.59 4.31

-

203.9 0.0 6

500. 251.3 1.44

 2.15 2.87

3.59 4.31

-

168.9 0.0 6

1000. 174.5 1.00

 1.50 1.99

2.49 2.99

-

133.9 0.0 6

1500. 63.9 0.36

 0.55 0.73

0.91 1.09

-

98.9 0.0 6

Minimum detailing -

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Page 717: International Codes v8i

2000. requirements ! 63.9 0.0 6

2500.

Minimum detailing

requirements !

-

28.9 0.0 6

3000.

Minimum detailing

requirements ! 12.7 0.0 5

3500.

Minimum detailing

requirements ! 47.7 0.0 5

4000.

Minimum detailing

requirements ! 82.7 0.0 5

4500.

95.0

0.55

 0.82 1.09 1.37 1.64

117.7 0.0 5

5000. 242.5 1.39

 2.08 2.77 3.46 4.16

152.7 0.0 5

5500. 302.5 1.73

 2.59 3.46 4.32 5.19

187.7 0.0 5

6000. 302.5 1.73

 2.59 3.46 4.32 5.19

216.1 0.0 5

Here Minimum detailing requirements! means that reinforcement is not requiredaccording to calculation.

12A.4 Columns

Reinforcement for columns of rectangular or circular cross-section can becalculated. Flexibility of columns can be evaluated in two ways. In the case of usualanalysis (command PERFORM  ANALYSIS) flexibility is assessed by parametersELY and ELZ, values of which should conform with recommendation of the CodeSNiP 2.03.01-84*. If P-DELTA (analysis according to deformed diagram) orNONLINEAR (nonlinear geometry) analysis is performed, values of parametersELY and ELZ should be close to zero, for example ELY = ELZ=0.01.

Longitudinal reinforcement for columns is calculated only from condition ofstrength. Longitudinal forces and bending moments in relation to local axesand  are taken into account in longitudinal reinforcement calculations.

For rectangular columns the following output is generated:

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l column number;

l column length and cross-sectional dimensions;

l distance of centroid of each longitudinal bar from the nearest edge of thecross-section;

l concrete class;

l longitudinal reinforcement class;

l range of longitudinal reinforcement bar diameters assumed in calculation;

l diameter of longitudinal reinforcement bars obtained in calculation;

l total quantity of longitudinal bars;

l quantity of longitudinal bars at each cross-section edge, directed parallel to

the local axis ;

l quantity of longitudinal bars at each cross-section edge, directed parallel to

the local axis  .

In nine columns of the table under the heading LONGITUDINAL REINFORCEMENTthe following output is presented:

Result

Section distance of the section from the “start” of the column, mm

Astot total cross-sectional area of longitudinal reinforcement, sq.cm

Asy cross-sectional area of longitudinal reinforcement bars at each edge of section,

directed parallel to the local axis , sq.cmAsz cross-sectional area of longitudinal reinforcement bars at each edge of section,

directed parallel to the local axis , sq.cmPercent reinforcement percentage in the section

Nx, Mz, My respective values of longitudinal force and bending moments in relation to the

local axes  and , determining cross-sectional area of longitudinalreinforcement

Load.N. number of loading version, determining cross-sectional area of longitudinal

reinforcement

Table 12A.6 - Column design output 1

An example of output of calculation results is presented below.

708— STAAD.Pro

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Page 719: International Codes v8i

COLUMN NO. 97 DESIGN RESULTS

(rectangular section)

Length - 4000 mm.

Section: B= 350 mm, H=350 mm.

Distance from edge of column cross section to center of each longitudinal

reinforcement  bar - 40 mm.

Concrete class - В25.0 (Rb=13.05 МPa; Gb2=0.9).

Class of longitudinal reinforcement - А-III (Rs=365.0 МPa; Rsc=365.0 МPa).

Diameter range of longitudinal reinforcement bars:

Dmin=16 mm . . . Dmax=32 mm

Diameter of longitudinal reinforcement bars from calculation d=20 mm.

Total number of reinforcement bars Ntot=6.

Number of longitudinal bars at each section edge parallel to the

local Y axis Nyy =2.

Number of longitudinal bars at each section edge parallel to the

local Z axis Nzz =3.

L O N G I T U D I N A L   R E I N F O R C E M E N TSection

m

Astot

sq.cm

Asy

sq.cm

Asz

sq.cm

Percent

%

Nx

kN

Mz

kNm

My

kNm

Load

N0. 16.42 3.01 6.20 1.34 285.5 81.9 0.0 64000. 15.35 3.01 5.67 1.25 397.3 95.3 0.0 5

Diameter of longitudinal reinforcement bars, total quantity of longitudinal bars aswell as quantity of longitudinal bars at each edge of the section obtained fromcalculation should be considered as recommendation. In this case arrangement ofreinforcement in the section depends on the orientation of the local axes and is asfollows:

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Calculated values of reinforcement cross-sectional areas are presented in the tableand they may differ from recommended on the lower side.

When it is not possible according to detailing provisions to arrange in the columnlongitudinal reinforcement determined from calculation additional message isderived.

For columns of circular section the following output is generated:

l column number;

l column length and diameter of cross-section;

l distance of centroid of each longitudinal bar to the edge of cross-section;

l longitudinal reinforcement class;

l assumed in calculation range of diameters of longitudinal reinforcementbars;

l diameter of longitudinal reinforcement bars obtained from calculation;

l quantity of longitudinal bars.

In seven columns of the table under the heading LONGITUDINALREINFORCEMENT the following results are presented:

Sectiondistance of the section from the “start” of the column, mm

Astot total cross-sectional area of longitudinal reinforcement, sq.cm

Per

cent

percentage of longitudinal reinforcement

Nx,

Mz, My

respective values of longitudinal force and bending moments in

relation to local axis  and , determining cross-sectional areaof longitudinal reinforcement

Load.

N.

number of loading version, determining cross-sectional area of

longitudinal reinforcement

710— STAAD.Pro

Russian Codes - Concrete Design Per Russian Code (SNiP 2.03.01-84*)

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An example of output of calculation results for a column of circular section ispresented below.

COLUMN NO. 80 DESIGN RESULTS

(circular section)

Length - 4000 mm.

Diameter: Dс= 350 mm.

Distance from edge of column cross section to center of each longitudinal

reinforcement bar - 50 mm.

Concrete class - В20.0 (Rb=10.35 МPa; Gb2=0.9).

Class of longitudinal reinforcement - А-III (Rs=365.0 МPa; Rsc=365.0 МPa).

Diameter range of longitudinal reinforcement bars:

Dmin=16 mm . . . Dmax=32 mm

Diameter of longitudinal reinforcement bars from calculation D=20 mm.

Total number of reinforcement bars Ntot =7.

L O N G I T U D I N A L   R E I N F O R C E M E N TSection

m

Astot

sq.cm

Percent

%

Nx

kN

Mz

kNm

My

kNm

Load

N0. 17.96 1.87 195.1 59.8 0.0 54000. 21.86 2.27 195.1 80.2 0.0 5

Diameter of longitudinal reinforcement bars, total quantity of longitudinal bars aswell as quantity of longitudinal bars at each edge of the section should beconsidered as recommendation.

Arrangement of reinforcement in section in this case is shown below:

Calculated cross-sectional areas of reinforcement presented in the table may differfrom recommended on the lower side.

International Design Codes Manual — 711

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When according to detailing provisions it is not possible to arrange in the columnlongitudinal reinforcement obtained from calculation additional message isderived.

12A.5 Two DimensionalElement (slabs, walls,shells)

In general case calculation of reinforcement for 2D members is carried out twotimes – according to conditions of strength and conditions of limiting openedwidth of cracks. If reinforcement is calculated according to conditions of strength,design values of loads have to be used, and for conditions of limiting crack width –characteristic (normative) loads are employed. Both calculations can be made inone session taking advantage of multiple analysis possibility of the programSTAAD.Pro.

Symmetric or nonsymmetrical reinforcement of 2D members is calculatedaccording to conditions of strength or according to conditions of limiting openedcrack width (see for example STA).

In reinforcement calculation for 2D members it is necessary to pay attention toarrangement of local axes of member and direction of reinforcement (see forexample CL and CRA).

An example of output of calculation results is presented bellow.

SLAB/WALL DESIGN RESULTS

(by stresses in local axes for limitation of crack width)Element Asx

sq.cm/m

Mx

kNm/m

Nx

kN/m

Load.N.

(X)

Asy

sq.cm/m

My

kNm/m

Ny

kN/m

LoadN.

(Y)

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60 TOP 0.00 - 4.9 0.00 1 0.00 - 4.5 0.00 1BOT      3.53 - 9.9 0.00 3 3.46 - 8.9 0.00 361 TOP 0.00 - 5.3 0.00 1 0.00 - 4.7 0.00 1BOT      3.87 - 10.7 0.00 3 3.65 - 9.4 0.00 362 TOP 0.00 - 5.6 0.00 1 0.00 - 4.8 0.00 1BOT      4.10 - 11.2 0.00 3 3.77 - 9.6 0.00 3

Here:

Result Description

Element number of finite element, TOP - “top” zone of member, BOT -“bottom” zone of member (“top” zone of member is determined by

positive direction of local axis -see Fig.2)Asx intensity of reinforcing in the first direction (parallel to the local

axis  ), sq.cm/mMx distributed bending moment in respect to the local axis ,

kNm/mNx distributed longitudinal force directed parallel to the axis ,

kNm/mLoad N.(X) number of loading version, determining intensity of reinforcing in

the first directionAsy intensity of reinforcing in the second direction (parallel to the local

axis  ), sq.cm/mMy distributed bending moment in respect to the local axis

kNm/mNy distributed longitudinal force directed parallel to the local axis

 kN/mLoad N.(Y) number of loading version, determining intensity of reinforcing in

the second direction

Table 12A.7 - Slab design output

International Design Codes Manual — 713

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Figure 2 - Local coordinate system of 2D member and notation of forces

714— STAAD.Pro

Russian Codes - Concrete Design Per Russian Code (SNiP 2.03.01-84*)

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Russian Codes - Steel Design Per Russian CodeSNiP 2.23-81* (Edition 1999)

12B.1 General

Design Code SNiP “Steel Structures” as majority of modern codes is based on themethod of limit states. The following groups of limit states are defined in the Code.

l The first group is concerned with losses of general shape and stability,failure, qualitative changes in configuration of structure. Appearance of non-allowable residual deformations, displacements, yielding of materials oropening of cracks.

l The second group is concerned with states of structures making worsenormal their service or reducing durability due to not allowable deflections,deviations, settlements, vibrations, etc.

Analysis of structures for the first limit state is performed using the maximum(design) loads and actions, which can cause failure of structures.

Analysis of structures for the second limit state is performed using service(normative) loads and actions. Relation between design and normative loads isreferred to as coefficient of load reliability, which is defined in SNiP 2.01.07.- 85“Loads and Actions”.

Coefficient of reliability for destination GAMA n according to SNiP 2.01.07.- 85shall be taken in to account determining loads or their combinations.

In this version of the program only members from rolled, tube and roll-formedassortment sections and also from compound such as double angles of T-typesections, double channels are presented. Design of other members of compoundsection will be presented in other versions of the program.

Economy of selected section is indicated by ratio (RATIO) σ/Ryycpresented in

calculation results. A section is economical when said ratio equals to 0,9 – 0,95.

12B.2 Built-in Russian Steel Section Library

Typical sections of members being checked and selected according to SNiP2.01.07.- 81* are presented in the following tables.

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Section SectionType

Designation form

I-beam (GOST 8239-89) ST I12

Regular I-beam (GOST26020-83)

ST B1-10

Broad-flanged I-beam(GOST 26020-83)

ST SH1-23

Column I-beam (GOST26020-83)

ST K1-20

Channel  (GOST 8240-89) ST C14

Equal legs angle (GOST8509-89)

ST L100x100x7

RA L100x100x7

Unequal legs angle (GOST8510-89)

ST L125x80x10

 RA L125x80x10

Pipes (welded and for gaspiping)

ST PIP102x5.5

or

ST PIPE OD 0.102 ID0.055

Roll-formed square andrectangular tubes

ST TUB160x120x3

or

Table 12B.1 - Typical Sections for Russian Steel Design

716— STAAD.Pro

Russian Codes - Steel Design Per Russian Code SNiP 2.23-81* (Edition 1999)

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Section SectionType

Designation form

ST TUBE TH 0.003WT 0.12 DT 0.16

Section SectionType

Designationform

Double channels D C14 SP0.01

(SP – cleardistancebetweenchannelwalls)

Double equal legs angles LDL100x100x7SP 0.01

(SP – cleardistancebetweenangle walls)

Double unequal legs angles with longlegs back to back

LDL125x80x10SP 0.01

(SP – cleardistancebetweenangle walls)

Double unequal legs angles withshort legs back to back

SDL125x80x10SP 0.01

(SP – clear

Table 12B.2 - Compound Sections for Russian Steel Design

International Design Codes Manual — 717

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Section SectionType

Designationform

distancebetweenangle walls)

Tee with flange at the top

Note: Flange of Tee beam is atthe top part of cross-section ifbeta angle = 0°, or at the bottompart if beta angle = 180°.

T I12

T B1-10

T SH1-23

T K1-20

For entry of cross-sectional dimensions command MEMBER PROPERTIES RUSSIANis used.

Example

UNITSMETER

MEMBER PROPERTYRUSSIAN

* I-BEAM

1 TO6 TABLE ST B1-10

* CHANNEL

7 TO 11 TABLE ST C14

* UNEQUAL LEGS ANGLE

12 TO 30 TABLE RA L125X80X10

* ROUND ASSORTMENT PIPE

31 TO 46 TABLE ST PIP102X5.5

* ROUND PIPE OF CROSS-SECTIONALDIMENSIONS DEFINED BYCLIENT

47 TO 60 TABLE ST PIPE OD 0.102 ID 0.055

* SQUARE TUBE FROMASSORTMENT

61 TO 68 TABLE ST TUB120X120X3

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Page 729: International Codes v8i

* RECTANGULAR TUBEOF CROSS-SECTIONALDIMENSIONDEFINED BYCLIENT

69 TO 95 TABLE ST TUBE TH 0.003WT 0.12 DT 0.16

* DOUBLE CHANNEL (DISTANCE BETWEENWALLS 10 ММ)

96 TO 103 TABLE D C14 SP 0.01

* DOUBLE UNEQUAL LEGS ANGLESWITH SHORT LEGS BACK-TO-BACK (DISTANCE BETWEENWALLS 10 ММ)

104 TO 105 TABLE SD L125X80X10 SP 0.01

* MEMBEROF TEE SECTION

106 TO 126 TABLE T SH1-23

* FLANGEOF T-BEAMS AT THE BOTTOMOF CROSS-SECTION

BETA 180.MEMB 116 TO 126

* ORIENTATION OF THE LOCAL ANGLE AXES IN RELATION TOTHEGLOBAL AXES OF THE STRUCTURE

BETA RANGLEMEMB 12 TO 30

COMMANDSOF OUTPUT DATA FOR CHECK AND SELECTION OFSECTIONS ARE LOCATED AFTER COMMANDSOF ANALYSIS AND,AS A RULE, AFTER OUTPUT COMMAND TOPRINT RESULTS OFCALCULATION.

12B.3 Member Capacities

Algorithms for selection and review of sections for steel members according toassortments and databases of the main rolled steel producers from given countriesand according to international standards as well are included in STAAD.Proprogram. In this program version only assortment sections can be utilized.

Example

* COMMAND OF ANALYSIS

PERFORMANALYSIS

* COMMAND OF LOADINGS AND THEIR COMBINATIONSCONSIDERED IN DESIGN

LOAD LIST 1 5 TO 9

International Design Codes Manual — 719

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* COMMAND TOSTART DESIGN ACCORDING TORUSSIAN CODE

PARAMETER

CODE RUSSIAN

* LIST OF PARAMETERS USED IN CHECKING AND SELECTING

BEAM 1. ALL

Obligatory parameter

LY 4.MEMB 1 TO 4

LZ 4.MEM 1 TO4

MAIN 1. ALL

SGR 3. ALL

SBLT 0 ALL

* PARAMETER OF OUTPUT AMOUNT OF INFORMATION ONCALCULATION RESULTS

TRACK 2. ALL

.

* COMMAND TOSTART SECTION CHECK PROCEDURE

CHECK CODE ALL

* COMMAND TOSTART SECTION SELECTION PROCEDURE

SELECT ALL

.

* COMMAND OF OUTPUT TOPRINT CONTENT OF ASSORTMENTTABLES

PRINT ENTIRE TABLE

* COMMAND OF OUTPUT TOPRINT SUMMARYOF STEELACCORDING TOSECTIONS

STEEL TAKEOFF

* COMMAND OF OUTPUT TOPRINT SUMMARYOF STEELACCORDING TOMEMBERS AND SECTIONS

STEELMEMBER TAKEOFF

720— STAAD.Pro

Russian Codes - Steel Design Per Russian Code SNiP 2.23-81* (Edition 1999)

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12B.3.1 Axial tension members

Stress in a section of axial tension member shall not exceed design strength Ryof

selected steel multiplied by coefficient of service conditions γc(KY and KZ), table 6

of SNiP 2.01.07.- 81*. Slenderness of tension member (CMM) shall not exceedslenderness limit indicated in table 20 of SNiP 2.01.07.- 81* (default value λ

u=

200, but another value can be defined). Net section factor (ratio Anet/Agross

(NSF))is used for tension member to allow for reduction of design cross-section area.

12B.3.2 Axial compression members

All axial compression members are calculated as long bars, i.e., with allowance forslenderness (λ = l

0/imin

). The calculation is performed in accordance with theclause 5.3 of SNiP 2.01.07.- 81*, buckling coefficient φ is determined by formula8-10. Effective bar lengths (within and out of plane) taking in to account role andlocation of the bar in the structure, as well as fixation of ends (l

0= μl), are

determined according to requirements of chapter 6 or addition 6 to SNiP 2.01.07.-81* and are set by specification of members. Slenderness of compression members(CMN) shall not exceed limit values given in table 19 of SNiP 2.01.07.- 81*. Value ofcoefficient α being used in table 19 is taken within limits from 0,5 to 1,0. Limitslenderness value depends on stress acting in the member, section area, bucklingcoefficient and design resistance of steel.

Since slenderness can be different in various planes the greatest slenderness isassumed in calculations.

12B.3.3 Flexural members

Members subjected to the action of bending moments and shear forces are calledflexural members.

Calculation of flexural members consists of verification of strength, stability anddeflection.

Normal and tangential stresses are verified by strength calculation of members.Normal stresses are calculated in the outermost section fibres. Tangential stressesare verified in the neutral axis zone of the same section. If normal stresses do notexceed design steel strength and tangential stresses do not exceed design value ofsteel shear strength R

sγsthen according to clause 5.14 of SNiP 2.01.07.- 81*

principal stresses are checked.

International Design Codes Manual — 721

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General stability of member subjected to bending in one plane are calculated inaccordance with clause 5.15 of SNiP 2.01.07.- 81*, and subjected to bending intwo planes – in accordance with “Guide to design of steel structures” (to SNiP2.01.07.- 81*). Coefficient φ

bvalue is determined according to appendix 7 of

SNiP 2.01.07.- 81*. Additional data about load (concentrated or distributed),numbers of bracing restrains of compression flanges, location of applied load arerequired. For closed sections it is assumed that coefficient φ

b= 1.0.

Simply supported (non-continuous) beams can be calculated in elastic as well as inelastic-plastic state according to requirements of clause 5.18 of SNiP 2.01.07.-81*. Calculation can be selected by specification of structure in input data.

Stiffness of flexural members is verified comparing input value of deflection limit(through parameter DFF) with maximum displacement of a section of flexuralmember allowing for load reliability coefficient, which is specified, in input data.Limit values of deflection are determined in accordance with SNiP 2.01.07.- 85“Loads and Actions. Addition chapter 10. Deflections and displacements”.Verification of deflection is performed only in the case of review (CHECK) problem.

12B.3.4 Eccentric compression/tension members

Eccentric compression or tension members are subjected to simultaneous action ofaxial force and bending moment. Bending moment appears due to eccentricapplication of longitudinal force or due to transverse force.

Stress in eccentric compression/tension members is obtained as a sum of stressesdue to axial force and bending.

Following the requirements of clause 5.25 of SNiP 2.01.07.- 81* resistance ofeccentric compression/tension member taking into consideration condition R

y<

530 MPa, τ < 0.5Rsand N/(A

nRy) > 0.1 is calculated by formula 49, and in other

cases-by formula 50. Calculations of stability verification are performed accordingto requirements of clauses 5.27, 5.30, 5.32 or 5.34.

Calculation for strength of eccentric tension members is made according toformula 50 of SNiP 2.01.07.- 81*.

When reduced relative eccentricitymef> 20 eccentric compression members are

calculated as flexural members (N = 0), whenmef< 20 strength by formula 49 is

not verified (clause 5.24).

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Russian Codes - Steel Design Per Russian Code SNiP 2.23-81* (Edition 1999)

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12B.4 Design Parameters

Information on parameters, data used for check and selection of sections in designof steel structures according to Russian Code is presented in the following table.

In this version of calculation according to requirements of SNiP 2.01.07.- 81* thereis common database of equal legs angles and unequal legs angles, thereforesolution of section selection problem may give equal legs angle as well as unequallegs angle irrespective of set at the beginning. The same is and with rectangularand square tubes.

Values of parameters do not depend on command UNIT. Only these values ofparameters, which differ from, defined in the program need to be included in theinput data file.

Review of sections (command CHECK) can be performed according to the first andthe second group of limit states. Selection of section (command SELECT) can beperformed only according to the first group of limit states with subsequentrecalculation and verification of selected section with allowance for deflection.

Calculation for the first group of limit states involves selection of membersaccording to strength and stability. Parameters CMN and CMM give opportunity to setslenderness limit for compression and tension members respectively for theirstability calculation, or refuse consideration of slenderness by setting defaultparameters. In this case selection of sections will be performed with considerationonly of strength check.

Check for deflection performed by setting parameter DFF (maximum allowablerelative deflection value) different from set in the program.

In the case of application of steel not defined by SNiP and/or GOST it is necessaryto set their design strength by parameters UNL and PY.

In determination of steel parameters SBLT and MAIN shall be approved (see Table12B.4).

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

International Design Codes Manual — 723

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ParameterName

DefaultValue

Description

BEAM 1

Member design parameter:

l BEAM = 0, Design members forforces at their ends or at thesections defined by SECTIONcommand;

l BEAM = 1, Calculate the major axismoment Mz at 13 points along thebeam and design beam at thelocation of maximum Mz;

l BEAM = 2, Same as BEAM=1, butadditional checks are carried out atbeam ends and at critical intermediate section;

l BEAM = 3, Calculate forces at 13points and perform design checksat all locations including the ends

CB 1

Place of loading on beam:

l CB = 1, for loading on top flange;

l CB = 2, for loading on bottomflange

Table 12B.3 - Parameters for Steel design according to RussianCode (SNiP II – 23 – 81*, edition 1990)

724— STAAD.Pro

Russian Codes - Steel Design Per Russian Code SNiP 2.23-81* (Edition 1999)

Page 735: International Codes v8i

ParameterName

DefaultValue

Description

СMM 0

Slenderness limit value for tensionmembers:

l СMM = 0, if slenderness issuppressed;

l СMM = 2, if ultimate slendernessvalue is "150";

l СMM = 2, if ultimate slendernessvalue is "200";

l СMM = 3, if ultimate slendernessvalue is "250";

l СMM = 4, if ultimate slendernessvalue is "300";

l СMM = 5, if ultimate slendernessvalue is "350";

l СMM = 6, if ultimate slendernessvalue is "400

Set slenderness limit value not equal to"0" for design with evaluation ofbuckling effect

International Design Codes Manual — 725

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ParameterName

DefaultValue

Description

CMN 0

Slenderness limit value for compressionmembers:

l СMN = 0, if slenderness issuppressed;

l СMN = 1, if slenderness limit valueis "120";

l СMN = 2, if slenderness limit valueis "210-60a";

l СMN = 3, if slenderness limit valueis "220-40a";

l СMN = 4, if slenderness limit valueis "220";

l СMN = 5, if slenderness limit valueis "180-60a";

l СMN = 6, if slenderness limit valueis "210-60a";

l СMN = 7, if slenderness limit valueis "210-60a";

l СMN = 8, if slenderness limit valueis "200";

l СMN = 9, if slenderness limit valueis "150";

Set slenderness limit value not equal to"0" for design with evaluation ofbuckling effect

726— STAAD.Pro

Russian Codes - Steel Design Per Russian Code SNiP 2.23-81* (Edition 1999)

Page 737: International Codes v8i

ParameterName

DefaultValue

Description

DFF 0.

Allowable limit of relative local deflection(Member length/Deflection Ratio):

Default value 0 is valid if design isapplied without deflection limitation.

Set for deflection check only

DMAX

[m]1. Maximum allowable section depth

DMIN

[m]0. Minimum allowable section depth

GAMC1 1.0Specific service condition coefficient forbuckling design

GAMC2 1.0Specific service condition coefficient forstrength design

KY 1.0Coefficient of effective length in respectto local axis Y (in plane XZ) 

KZ 1.0Coefficient of effective length in respectto local axis Z (in plane XY) 

LEG 4

Type and position of loading on beam:

l LEG = 1, for loading concentratedin the middle span;

l LEG = 2, for loading concentratedin the quarter of the span;

l LEG = 3, for loading concentratedat the end of bracket;

l LEG = 4, for loading uniformlydistributed on beam;

l LEG = 5, for loading uniformlydistributed on bracket

International Design Codes Manual — 727

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ParameterName

DefaultValue

Description

LY

[m]

Memberlength

Effective length in respect to local axis Y(in plane XZ)

Default is selected member's length

LZ

[m]

Memberlength

Effective length in respect to local axis Z(in plane XY)

Default is selected member's length

MAIN  1

Standard of steel grade (GOST):

l MAIN = 1, if Standard of steelgrade is GOST27772-88;

l MAIN = 2, if Standard of steelgrade is GOST10705-80;

l MAIN = 3, if Standard of steelgrade is GOST10706-76;

l MAIN = 4, if Standard of steelgrade is GOST8731-87;

l MAIN = 5, if Standard of steelgrade is TY14-3-567-76

NSF 1.0Net section factor for tension membersor web section area weakening factor forbending members

PY

[MPa]0

Design steel strength (yield strength):

If parameters MAIN according toStandard of steel grade (GOST) and bySGR according to Steel grade (STAL) arenot defined

RATIO 1.0Ratio between design and characteristicloads values

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ParameterName

DefaultValue

Description

SBLT 0

Number of lateral bracing restraintsalong the span:

l SBLT = 0, if beam not fixed;

l SBLT = 1, one restraint in themiddle of the span;

l SBLT = 2, 3, etc. number ofuniformly spaced lateral supportsalong the span

SGR 1Steel grade (STAL). Refer to Table 12B.4below.

TB 0

Indication of elastic or elastic-plasticcalculation:

l TB = 0, for elastic calculation

l TB = 1, for elastic-plasticcalculation

Set for members under bending or non-axial compression/tension only.

International Design Codes Manual — 729

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ParameterName

DefaultValue

Description

TRACK 0

Output parameter:

l TRACK = 0, for suppressed outputinformation;

l TRACK = 1, for extended outputinformation;

l TRACK = 2, for advanced outputinformation

UNL

[MPa]0

Design steel strength (ultimatestrength):

If parameters MAIN according toStandard of steel grade (GOST) and bySGR according to Steel grade (STAL) arenot defined

SGRValue

SteelParameterMAIN

GOSTFor

members*

1 C235 1GOST27772-88

GT, F

2 C245 1 “ GT, F

3 C255 1 “ GT, F

4 C275 1 “ GT, F

5 C285 1 “ GT, F

6 C345 1 “ GT, F

7 C345K 1 “ GT, F

8 C375 1 “ GT, F

9 C390 1 “ F

Table 12B.4 - Steel types for design of steel structures accordingto SNiP 2.01.07.-81* (table 51 and 51a)

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Page 741: International Codes v8i

SGRValue

SteelParameterMAIN

GOSTFor

members*

10 C390K 1 “ F

11 C440 1 “ F

12 C590 1 “ F

13 C590К 1 “ F

14 BSt3kp 2GOST10705-80*

Tube

15 BSt3ps2

3

GOST10705-80*

GOST10706-76*

Tube

16 BSt3sp2

3

GOST10705-80*

GOST10706-76*

Tube

17 20 4GOST 8731-87

Tube

18 16G2АF 5TY 14-3-567-76

Tube

*GT – members from sheet and roll-formed tubes

F – rolled section steel

12B.5 Member Selection and Code Check

Both code checking and member selection options are available in SNiP 2.23-81*.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

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Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

Output of selection and check results are given in suppressed, extended andadvanced forms. Form of output results depends on value of parameter TRACK.

Results are presented in tables. Three versions of output results are possible:suppressed – results according the critical strength condition (TRACK=0),extended - results according to all check conditions (TRACK=1) and advanced –complete information on results of member design (TRACK=2).

In tables of results common data for all TRACKs are indicated:

(TRACK=2).

In tables of results common data for all TRACKs are indicated:

number of member;

type and number of cross-section;

result obtained (ACCEPTED – requirements are met, FAILURE – are not met);

abbreviated name of normative document (code, standard) (SNiP);

number of check clause;

safety of strength (ratio between design and normative values);

number of the most unfavorable loading;

value of longitudinal force acting in the member with subscript indicating itsdirection (“C” – compression, “P” – tension);

bending moments in relation to local member axes Z and Y;

distance to section, in which the most unfavorable combination of forces acts.

Example of TRACK 0 output

In suppressed form (TRACK 0) results are presented according to the critical checkfor given member with indication of SNiP clause number, according to whichstrength safety of the member is minimum.

========================================================================MEMBER CROSS RESULT/ CRITICAL COND/ RATIO/ LOADING/

SECTION NO. FX MZ MY LOCATION

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Russian Codes - Steel Design Per Russian Code SNiP 2.23-81* (Edition 1999)

Page 743: International Codes v8i

========================================================================1 I60 PASS SNiP- 5.18 0.68 1

0.000E+00 -4.650E+02 0.000E+00 3.000E+00

Example of TRACK 1 output

In extended form (TRACK 1) results are presented on the basis of all required bySNiP checks for given stress state.

========================================================================MEMBER CROSS RESULT/ CRITICAL COND/ RATIO/ LOADING/

SECTION NO. FX MZ MY LOCATION========================================================================

1 I60 PASS SNiP- 5.18 0.68 10.000E+00 -4.650E+02 0.000E+00 3.000E+00

1 I60 PASS SNiP- DISPL 0.36 10.000E+00 -4.650E+02 0.000E+00 3.000E+00

Example of a TRACK 2 output

In advanced form (TRACK=2) in addition to tabled results supplementaryinformation is presented.

l Material characteristics:

l Steel;

l Design resistance;

l Elasticity modulus;

l Section characteristics:

l Length of member;

l Section area;

l Net area;

l Inertia moment (second moment of area) (I);

l Section modulus (W);

l First moment of area (S);

l Radius of gyration;

l Effective length;

l Slenderness;

l Results are presented in two columns, Z and Y respectively.

l Design forces:

International Design Codes Manual — 733

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l Longitudinal force;

l Moments;

l Shear force.

Signs “+” and “-“ indicate direction of acting longitudinal force, bending momentsand shear forces in accordance with sign rules assumed in program STAAD.

Check results in advanced form are presented with values of intermediateparameters by formulas in analytical and numerical expression with indication ofSNiP clause.

========================================================================MEMBER CROSS RESULT/ CRITICAL COND/ RATIO/ LOADING/

SECTION NO. FX MZ MY LOCATION========================================================================

1 I60 PASS SNiP- 5.18 0.68 10.000E+00 -4.650E+02 0.000E+00 3.000E+00

1 I60 PASS SNiP- DISPL 0.36 10.000E+00 -4.650E+02 0.000E+00 3.000E+00

MATERIAL DATASteel =C245Modulus of elasticity = 206.E+06 KPADesign Strength (Ry) = 240.E+03 KPA

SECTION PROPERTIES (units - m)Member Length = 6.00E+00Gross Area = 1.38E-02Net Area = 1.38E-02

z-axis y-axisMoment of inertia (I) : 768.E-06 173.E-07Section modulus (W) : 256.E-05 182.E-06First moment of area (S) : 149.E-05 156.E-06Radius of gyration (i) : 236.E-03 354.E-04Effective Length : 600.E-02 600.E-02Slenderness : 0.00E+00 0.00E+00

DESIGN DATA (units -kN,m)SNiP II-23-81*/1998Axial force : 0.00E+00

z-axis y-axisMoments : -465.E+00 0.00E+00Shear force : 0.00E+00 500.E-02

CRITICAL CONDITIONS FOR EACH CLAUSE CHECKF.(39) M/(C1*Wmin)=-465.0E+00/ 1.12E+00* 2.56E-03= 162.1E+03F.(41) Q/(H*T)= 500.0E-02/ 6.00E-01* 1.20E-02= 694.E+00RY*GAMAC= 240.0E+03ACTUAL SECTION DISPLACEMENT = 1.094E-02 MMAXIMUM MEMBER DEFLECTION = 1.094E-02 M Loading No. 1ULTIMATE ALLOWABLE DEFLECTION VALUE = 3.000E-02 M

Conventional notations assumed in presentation of results: “+”, “-“, “/”, “*”,”**”,“SQRT”, their respective meanings (i.e., addition, subtraction, division,

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multiplication, raising to the second power (squared), and square root).Conventional notations of stresses, coefficients and characteristics of steelresistance comply with accepted in the SNiP standard. Only Greek letters arechanged by their names (e.g., , γ

c-GAMAC; α-ALPHA; β-BETA, η-ETA, φ-PHI, etc.).

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Section 13

South African Codes

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South African Codes - Concrete Design PerSABS-0100-1

13A.1 Design Operations

STAAD has the capability for performing design of concrete beams and columnsaccording to the South African code SABS 0100-1.  The 2000 revision of the code iscurrently implemented.  Design can be performed for beams (flexure, shear andtorsion) and columns (axial load + biaxial bending). Given the width and depth (ordiameter for circular columns) of a section, STAAD will calculate the requiredreinforcement.

13A.2 Design Parameters

The program contains a number of parameters which are needed to perform andcontrol the design to SABS 0100-1. These parameters not only act as a method toinput required data for code calculations but give the engineer control over theactual design process. Default values of commonly used parameters forconventional design practice have been chosen as the basis. Table 13A.1 contains acomplete list of available parameters with their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as SABS0100.

Design Code to follow.

See section 5.52.2 of the TechnicalReference Manual.

BRACE 0.0 Column bracing:

0. Column braced in both direc-tions.

Table 13A.1 - South African Concrete Design SABS 0100-1 Param-eters

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ParameterName

DefaultValue

Description

1. Column braced about local Ydirection only

2. Column unbraced about localZ direction only

3. Column unbraced in both Yand Z directions

CLB 20mm Clear Cover for outermost bottomreinforcement

CLS 20mm Clear Cover for outermost sidereinforcement

CLT 20mm Clear Cover for outermost topreinforcement

DEPTH YD Depth of concrete member, incurrent units. This value default isas provided as YD in MEMBERPROPERTIES.

ELY 1.0 Member length factor about local Ydirection for column design.

ELZ 1.0 Member length factor about local Zdirection for column design.

FC 30N/mm2 Concrete Yield Stress / cubestrength, in current units.

FYMAIN 450 N/mm2 Yield Stress for main reinforcement,in current units.

FYSEC 450N/mm2 Yield Stress for secondaryreinforcement a, in current units.Applicable to shear bars in beams

MAXMAIN 50mm Maximum required reinforcementbar size Acceptable bars are perMINMAIN above.

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ParameterName

DefaultValue

Description

MINMAIN 8mm Minimummain reinforcement barsize Acceptable bar sizes: 6 8 10 1216 20 25 28 32 36 40 50 60

MINSEC 8mm Minimum secondary bar size a.Applicable to shear reinforcementin beams

TRACK 0.0 Output detail

0. Critical Moment will not beprinted with beam designreport. Column design givesno detailed results.

1. For beam gives min/max steel% and spacing. For columnsgives a detailed table of out-put with additional momentscalculated.

2. Output of TRACK 1.0 List ofdesign sag/hog moments andcorresponding required steelarea at each section ofmember

WIDTH ZD Width of concrete member, incurrent units. This value default isas provided as ZD in MEMBERPROPERTIES.

13A.3 Member Dimensions

Concrete members that are to be designed by STAAD must have certain sectionproperties input under the MEMBER PROPERTIES command. The following exampledemonstrates the required input: 

UNIT MM

MEMBER PROPERTIES

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*RECTANGULAR COLUMN 300MMWIDE X 450MMDEEP

1 3 TO 7 9 PRISM YD 450. ZD 300.

*CIRCULAR COLUMN 300MMDIAMETER

11 13 PR YD 300.

* T-SECTION - FLANGE 1000.X 200.(YD-YB)

* - STEM 250(THICK) X 350.(DEEP)

14 PRISM YD 550. ZD 1000. YB 350. ZB 250.

In the above input, the first set of members are rectangular (450mm depth x300mmwidth) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with 300mm diameter. Note that area(AX) is not provided for these members. If shear area areas (AY & AZ ) are to beconsidered in analysis, the user may provide them along with YD and ZD. Alsonote that if moments of inertias are not provided, the program will calculate themfrom YD and ZD. Finally a T section can be considered by using the third definitionabove.

13A.4 Beam Design

Beam design includes flexure, shear and torsion. For all types of beam action, allactive beam loadings are scanned to create moment and shear envelopes andlocate the critical sections. The total number of sections considered is thirteen.From the critical moment values, the required positive and negative bar pattern isdeveloped. Design for flexure is carried out as per clause no. 4.3.3.4.

Shear design as per SABS 0100 clause 4.3.4 has been followed and the procedureincludes computation of critical shear values. From these values, stirrup sizes arecalculated with proper spacing. If torsion is present, the program will alsoconsider the provisions of SABS 0100 clause 4.3.5. Torsional reinforcement isseparately reported.

A TRACK 2 design output is presented below.

B E A M  N O.       4   D E S I G N  R E S U L T S

M20                    Fe450 (Main)               Fe450 (Sec.)

LENGTH:  7500.0 mm      SIZE:   380.0 mm X  715.0 mm   COVER:25.0 mm

DESIGN LOAD SUMMARY (KN MET)

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--------------------------------------------------------------------

SECTION |FLEXURE  (Maxm. Sagging/Hogging moments)|           SHEAR

(in mm) |    MZ    Load Case     MX   Load Case  |    VY       P      Load Case

--------------------------------------------------------------------

0.0 |   135.75       5       -3.44      5    |  152.06    50.62      4

|  -295.92       4                       |

625.0 |   189.16       5       -3.43      5    |  133.95    48.87      4

|  -236.52       4                       |

1250.0 |   231.25       5       -3.41      5    |  115.84    47.12      4

|  -188.44       4                       |

1875.0 |   262.01       5       -3.40      5    |   97.73    45.37      4

|  -151.68       4                  |

2500.0 |   281.46       5       -3.39      5    |   79.61    43.63      4

|  -126.24       4                       |

3125.0 |   289.59       5       -3.37      5    |   61.50    41.88      4

|  -112.12       4          |

3750.0 |   286.39       5       -3.36      4    |  -62.13    40.13      5

|  -109.32       4                       |

4375.0 |   271.88       5       -3.37      4    |  -80.25    41.88      5

|  -117.84       4                       |

5000.0 |   246.05       5       -3.39      4    |  -98.36    43.63      5

|  -137.68       4                       |

5625.0 |   208.89       5       -3.40      4    | -116.47    45.37      5

|  -168.84       4                       |

6250.0 |   160.42       5       -3.41      4    | -134.58    47.12      5

|  -211.33       4                       |

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6875.0 |   100.62       5       -3.43      4    | -152.70    48.87      5

|  -265.13       4                       |

7500.0 |    29.50       4       -3.44      4    | -170.81    29.63      4

|  -330.25       5                 |

 SUMMARY OF REINF. AREA FOR FLEXURE DESIGN (Sq.mm)

--------------------------------------------------------------------

SECTION | TOP            | BOTTOM          | STIRRUPS

(in mm) | Reqd./Provided reinf.   | Reqd./Provided reinf.   | (2 legged)

--------------------------------------------------------------------

0.0 | 1232.70/1256.64( 4-20í )|  543.40/ 565.50( 5-12í )|  8í  @ 425mm

625.0 |  960.90/ 981.74( 2-25í )|  754.32/ 791.70( 7-12í )|  8í  @ 510mm

1250.0 | 751.24/ 791.70( 7-12í )|  937.49/ 942.48( 3-20í )|  8í  @510 mm

1875.0 |  596.52/ 603.18( 3-16í )| 1075.72/1206.36( 6-16í )|  8í  @510 mm

2500.0 |  543.40/ 565.50( 5-12í )| 1165.13/1206.36( 6-16í )|  8í  @510 mm

3125.0 |  543.40/ 565.50( 5-12í )| 1203.00/1206.36( 6-16í )|  8í  @220 mm

3750.0 |  543.40/ 565.50( 5-12í )| 1188.08/1206.36( 6-16í )|  8í  @220 mm

4375.0 |  543.40/ 565.50( 5-12í )| 1120.87/1206.36( 6-16í )|  8í  @220 mm

5000.0 |  543.40/ 565.50( 5-12í )| 1003.50/1005.30( 5-16í )|  8í  @220 mm

5625.0 |  668.18/ 678.60( 6-12í )|  839.38/ 904.80( 8-12í )|  8í  @220 mm

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6250.0 |  849.99/ 904.80( 8-12í )|  632.84/ 678.60( 6-12í )|  8í  @ 220mm

6875.0 | 1089.94/1206.36( 6-16í )|  543.40/ 565.50( 5-12í )|  8í  @220 mm

7500.0 | 1397.16/1407.42( 7-16í )|  543.40/ 565.50( 5-12í )|  8í  @220 mm

--------------------------------------------------------------------

TORSION REINFORCEMENT: Not required

13A.5 Column Design

Columns are designed for axial force and biaxial bending at the ends. All activeloadings are tested to calculate reinforcement. The loading which producesmaximum reinforcement is called the critical load and is displayed. Therequirements of SABS 0100-1 clause 4.7 are followed, with the user having controlon the effective length in each direction by using the ELZ and ELY parameters asdescribed in table 12A.1. Bracing conditions are controlled by using the BRACEparameter. The program will then decide whether or not the column is short orslender and whether it requires additional moment calculations. For biaxialbending, the recommendations of 4.7.4.4 of the code are considered.

Column design is done for square, rectangular and circular sections. Forrectangular and square sections, the reinforcement is always assumed to bearranged symmetrically. This causes slightly conservative results in certain cases.Table 12A.3 shows typical column design results.

Using parameter TRACK 1.0, the detailed output below is obtained. TRACK 0.0would merely give the bar configuration, required steel area and percentage,column size and critical load case.

TABLE 12A.3 -COLUMN DESIGN OUTPUT

================================================-=======================

C O L U M N   N O.      1  D E S I G N   R E S U L T S

M20                    Fe450 (Main)               Fe450 (Sec.)

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LENGTH: 3660.0 mm  CROSS SECTION:  750.0 mm X 460.0 mmCOVER:40.0mm

** GUIDING LOAD CASE:    4 END JOINT:     1  SHORT COLUMN     

DESIGN FORCES (KNS-MET)

-----------------------

DESIGN AXIAL FORCE (Pu)             :   915.6

About Z     About Y

INITIAL MOMENTS                     :    0.00            0.00

MOMENTS DUE TO MINIMUM ECC.         :   18.31           18.31

SLENDERNESS RATIOS                  :    7.96            4.88

ADDITION MOMENTS (Maddz and Maddy)  :    0.00            0.00

TOTAL DESIGN MOMENTS                :  555.13           21.91

REQD. STEEL AREA   :   3349.20 Sq.mm.

REQD. CONCRETE AREA:      114451.62 Sq.mm.

MAIN REINFORCEMENT : Provide  32 - 12 dia. (1.05%,   3619.20 Sq.mm.)

(Equally Distributed)

TIE REINFORCEMENT  : Provide  8 mm dia. rectangular ties @ 140 mm c/c

SECTION CAPACITY BASED ON REINFORCEMENT REQUIRED (KNS-MET)

----------------------------------------------------------

Puz :   2160.42   Muz1 :    570.23   Muy1 :    563.74

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South African Codes - Steel Design Per SABStandard SAB0162-1:1993

13B.1 General

The South African Steel Design facility in STAAD is based on the SAB StandardSAB0162-1: 1993, Limit States Design of Steel Structures. A steel section libraryconsisting of South African Standards shapes is available for member propertyspecification.

The design philosophy embodied in this specification is based on the concept oflimit state design. Structures are designed and proportioned taking intoconsideration the limit states at which they would become unfit for their intendeduse. Two major categories of limit-state are recognized - ultimate andserviceability. The primary considerations in ultimate limit state design are strengthand stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all steelstructures under various loading conditions and at the same time the chances oflimits being surpassed are acceptably remote.

In the STAAD implementation, members are proportioned to resist the design loadswithout exceeding the limit states of strength, stability and serviceability.Accordingly, the most economic section is selected on the basis of the least weightcriteria as augmented by the designer in specification of allowable member depths,desired section type, or other such parameters. The code checking portion of theprogram checks whether code requirements for each selected section are met andidentifies the governing criteria.

The next few sections describe the salient features of the STAAD implementation ofSAB0162-1: 1993. A detailed description of the design process along with itsunderlying concepts and assumptions is available in the specification document.

13B.2 Analysis Methodology

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary and combination loading conditions provided bythe user. The user is allowed complete flexibility in providing loading specificationsand using appropriate load factors to create necessary loading situations.Depending upon the analysis requirements, regular stiffness analysis or P-Delta

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analysis may be specified. Dynamic analysis may also be performed and the resultscombined with static analysis results.

Refer to Section 5.37 of the Technical Reference Manual for additionalinformation.

13B.3 Member Property Specifications

For specification of member properties, the steel section library available in STAADmay be used. The next section describes the syntax of commands used to assignproperties from the built-in steel table. Member properties may also be specifiedusing the User Table facility. For more information on these facilities, refer toSection 1.7 the STAAD Technical Reference Manual.

13B.4 Built-in Steel Section Library

The following information is provided for use when the built-in steel tables are tobe referenced for member property specification. These properties are stored in adatabase file. If called for, the properties are also used for member design. Sincethe shear areas are built into these tables, shear deformation is always consideredduring the analysis of these members.

Refer to Section 1.7.2 of the Technical Reference Manual for additionalinformation.

I Shapes

The following example illustrates the specification of I- shapes.

1 TO 15 TABLE ST IPE-AA100

H shapes

Designation of H shapes in STAAD is as follows.

For example,

18 TO 20 TABLE ST 152X37UC

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PG shapes

Designation of PG shapes in STAAD is as follows.

100 TO 150 TABLE ST 720X200PG

Channel Sections (C &MC shapes)

C and MC shapes are designated as shown in the following example. 

3 TABLE ST 127X64X15C

Double Channels

Back to back double channels, with or without spacing between them, are specifiedby preceding the section designation by the letter D. For example, a back to backdouble channel section PFC140X60 without spacing in between should be specifiedas:

100 TO 150 TABLE D PFC140X60

A back-to-back double channel section 140X60X16C with spacing 0.01unitlength inbetween should be specified as:

100 TO 150 TABLE D 140X60X16C SP 0.01

Note: The specification SP after the section designation is used for providingthe spacing. The spacing should always be provided in the current length unit.

Angles

To specify angles, the letter L succeeds the angle name. Thus, a 70X70 angle with a25mm thickness is designated as 70X70X8L. The following examples illustrateangle specifications.

100 TO 150 TABLE ST 70X70X8L

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Note that the above specification is for “standard” angles. In this specification, thelocal z-axis (see Fig. 2.6 in the Technical Reference Manual) corresponds to the Y’-Y’ axis shown in the CSA table. Another common practice of specifying anglesassumes the local y-axis to correspond to the Y’-Y’ axis. To specify angles inaccordance with this convention, the reverse angle designation facility has beenprovided. A reverse angle may be specified by substituting the word ST with theword RA. Refer to the following example for details.

100 TO 150 TABLE RA 45X45X3L

The local axis systems for STANDARD and REVERSE angles are shown in Fig. 2.6of the STAAD Technical Reference manual.

Double Angles

To specify double angles, the specification ST should be substituted with LD (forlong leg back-to-back) or SD (short leg back-to-back). For equal angles, either SDor LD will serve the purpose. Spacing between angles may be provided by usingthe word SP followed by the value of spacing (in current length unit) after sectiondesignation.

100 TO 150 TABLE LD 50X50X3L

3 TABLE LD 40X40X5L SP 0.01

The second example above describes a double angle section consisting of40X40X5 angles with a spacing of 0.01 length units.

Tees

Tee sections obtained by cutting W sections may be specified by using the Tspecification instead of ST before the name of the W shape. For example:

100 TO 150 TABLE T IPE-AA180

will describe a T section cut from a IPE-AA180 section.

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Rectangular Hollow Sections

These sections may be specified in two possible ways. Those sections listed in theSAB tables may be specified as follows.

100 TO 150 TABLE ST TUB60X30X2.5

In addition, any tube section may be specified by using the DT(for depth), WT(forwidth), and TH(for thickness) specifications. For example:

100 TO 150 TABLE ST TUBE TH 3WT 100 DT 50

will describe a tube with a depth of 50mm, width of 100mm. and a wall thickness of3mm. Note that the values of depth, width and thickness must be provided incurrent length unit.

Circular Hollow Sections

Sections listed in the SAB tables may be provided as follows:

100 TO 150 TABLE ST PIP34X3.0CHS

In addition to sections listed in the SAB tables, circular hollow sections may bespecified by using the OD (outside diameter) and ID (inside diameter)specifications.

For example:

100 TO 150 TABLE ST PIPE OD 50 ID 48

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will describe a pipe with an outside diameter of 50 length units and insidediameter of 48 length units. Note that the values of outside and inside diametersmust be provided in terms of current length unit.

Sample input file to demonstrate usage of South African shapes is shown below.

STAAD PLANE

START JOB INFORMATION

ENGINEER DATE 30-MAR-05

END JOB INFORMATION

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 9 0 0; 3 0 6 0; 4 3 6 0; 5 6 6 0; 6 9 6 0; 7 0 10.5 0;

8 9 10.5 0; 9 2.25 10.5 0; 10 6.75 10.5 0; 11 4.5 10.5 0; 12 1.5 11.40;

13 7.5 11.4 0; 14 3 12.3 0; 15 6 12.3 0; 16 4.5 13.2 0;

MEMBER INCIDENCES

1 1 3; 2 3 7; 3 2 6; 4 6 8; 5 3 4; 6 4 5; 7 5 6; 8 7 12; 9 12 14;

10 14 16; 11 15 16; 12 13 15; 13 8 13; 14 9 12; 15 9 14; 16 11 14;

17 11 15; 18 10 15; 19 10 13; 20 7 9; 21 9 11; 22 10 11; 23 8 10;

MEMBER PROPERTY SAFRICAN

1 TABLE ST IPE-AA100

2 TABLE T IPE120

3 TABLE ST 152X23UC

4 TABLE T 152X23UC

5 TABLE ST 812X200PG

6 TABLE T 812X200PG

7 TABLE ST 178X54X15C

8 TABLE D 178X54X15C

9 TABLE D 178X54X15C SP 0.1

10 TABLE ST 25X25X5L

11 TABLE RA 25X25X5L

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12 TABLE LD 25X25X5L

13 TABLE SD 25X25X5L

14 TABLE LD 25X25X5L SP 0.1

15 TABLE SD 25X25X5L SP 0.1

16 TABLE ST TUB40X2.5SHS

17 TABLE ST TUBE TH 0WT 0 DT 50

18 TABLE ST TUBE TH 0.02WT 100 DT 50

20 TABLE ST PIP48X2.0CHS

21 TABLE ST PIPE OD 0.5 ID 0.48

PRINT MEMBER PROPERTIES

FINISH

13B.5 Section Classification

The SAB specification allows inelastic deformation of section elements. Thus, localbuckling becomes an important criterion. Steel sections are classified as plastic(Class 1), compact (Class 2), noncompact (Class 3), or slender element (Class 4)sections depending upon their local buckling characteristics (See Clause 11.2 andTable 1 of SAB0162-1:1993). This classification is a function of the geometricproperties of the section. The design procedures are different depending on thesection class. STAAD determines the section classification for the standard shapesand user specified shapes. Design is performed for sections that fall into thecategory of Class 1,2, or 3 sections only. Class 4 sections are not designed bySTAAD.

13B.6 Member Resistances

The member resistances are calculated in STAAD according to the proceduresoutlined in section 13 of the specification. These depend on several factors such asmembers’ unsupported lengths, cross-sectional properties, slenderness factors,unsupported width to thickness ratios and so on. Note that the programautomatically takes into consideration appropriate resistance factors to calculatemember resistances. Explained here is the procedure adopted in STAAD forcalculating the member resistances.

All the members are checked against allowable slenderness ratio as per Cl.10.2 ofSAB0162-1: 1993.

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Axial Tension

The criterion governing the capacity of tension members is based on two limitstates. The limit state of yielding in the gross section is intended to preventexcessive elongation of the member. The second limit state involves fracture at thesection with the minimum effective net area. The net section area may be specifiedby the user through the use of the parameter NSF (see Table 13B.1). STAADcalculates the tension capacity of a member based on these two limits states perCl.13.2 of SAB0162-1: 1993. Parameters FYLD, FU, and NSF are applicable forthese calculations.

Axial Compression

The compressive resistance of columns is determined based on Clause 13.3 of thecode. The equations presented in this section of the code assume that thecompressive resistance is a function of the compressive strength of the grosssection (Gross section Area times the Yield Strength) as well as the slendernessfactor (KL/r ratios). The effective length for the calculation of compressionresistance may be provided through the use of the parameters KX, KY, KZ, LX, LY,and LZ (see Table 13B.1). Some of the aspects of the axial compression capacitycalculations are:

1. For frame members not subjected to any bending, and for truss members,the axial compression capacity in general column flexural buckling iscalculated from Cl.13.3.1 using the slenderness ratios for the local Y-Y andZ-Z axis. The parameters KY, LY, KZ, and LZ are applicable for this.

2. For single angles, asymmetric or cruciform sections are checked as towhether torsional-flexural buckling is critical. But for KL/r ratio exceeding50,as torsional flexural buckling is not critical, the axial compressioncapacities are calculated by using Cl.13.3. The reason for this is that theSouth African code doesn’t provide any clear guidelines for calculating thisvalue. The parameters KY, LY, KZ, and LZ are applicable for this.

3. The axial compression capacity is also calculated by taking flexural-torsionalbuckling into account. Parameters KX and LX may be used to provide theeffective length factor and effective length value for flexural-torsionalbuckling. Flexural-torsional buckling capacity is computed for singlechannels, single angles, Tees and Double angles.

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4. While computing the general column flexural buckling capacity of sectionswith axial compression + bending, the special provisions of 13.8.1(a),13.8.1(b) and 13.8.1(c) are applied. For example, Lambda = 0 for 13.8.1(a),K=1 for 13.8.1(b), etc.)

Bending

The laterally unsupported length of the compression flange for the purpose ofcomputing the factored moment resistance is specified in STAAD with the help ofthe parameter UNL. If UNL is less than one tenth the member length (memberlength is the distance between the joints of the member), the member is treated asbeing continuously laterally supported. In this case, the moment resistance iscomputed from Clause 13.5 of the code. If UNL is greater than or equal to one-tenth the member length, its value is used as the laterally unsupported length. Theequations of Clause 13.6 of the code are used to arrive at the moment of resistanceof laterally unsupported members. Some of the aspects of the bending capacitycalculations are:

1. The weak axis bending capacity of all sections except single angles iscalculated as:

For Class 1 & 2 sections

Phi*Py*Fy

For Class 3 sections

Phi*Sy*Fy 

Where:

Phi = Resistance factor = 0.9

Py = Plastic section modulus about the local Y axis

Sy = Elastic section modulus about the local Y axis

Fy = Yield stress of steel

2. Single angles sections are not designed by STAAD, as the South African codedoesn’t provide any clear guidelines for calculating this value.

3. For calculating the bending capacity about the Z-Z axis of singly symmetric

International Design Codes Manual — 755

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shapes such as Tees and Double angles, SAB0162-1: 1993 stipulates inClause 13.6(b), page 31, that a rational method. 

Axial compression and bending

The member strength for sections subjected to axial compression and uniaxial orbiaxial bending is obtained through the use of interaction equations. In theseequations, the additional bending caused by the action of the axial load isaccounted for by using amplification factors. Clause 13.8 of the code provides theequations for this purpose. If the summation of the left hand side of theseequations exceeds 1.0 or the allowable value provided using the RATIO parameter(see Table 13B.1), the member is considered to have FAILed under the loadingcondition.

Axial tension and bending

Members subjected to axial tension and bending are also designed usinginteraction equations. Clause 13.9 of the code is used to perform these checks.The actual RATIO is determined as the value of the left hand side of the criticalequation.

Shear

The shear resistance of the cross section is determined using the equations ofClause 13.4 of the code. Once this is obtained, the ratio of the shear force actingon the cross section to the shear resistance of the section is calculated. If any ofthe ratios (for both local Y & Z axes) exceed 1.0 or the allowable value providedusing the RATIO parameter (see Table 13B.1), the section is considered to havefailed under shear. The code also requires that the slenderness ratio of the web bewithin a certain limit (See Cl.13.4.1.3, page 29 of SABS 0162-1:1993). Checks forsafety in shear are performed only if this value is within the allowable limit. Usersmay by-pass this limitation by specifying a value of 2.0 for the MAIN parameter.

13B.7 Design Parameters

The design parameters outlined in table below may be used to control the designprocedure. These parameters communicate design decisions from the engineer tothe program and thus allow the engineer to control the design process to suit anapplication's specific needs.

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The default parameter values have been selected such that they are frequently usednumbers for conventional design. Depending on the particular designrequirements, some or all of these parameter values may be changed to exactlymodel the physical structure.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

Default Value Description

CODE - Must be specified SAB0162.

Design Code to follow.

See section 5.48.1 of the Technical Reference Manual.

BEAM 0 0 - Perform design at ends and those locations specified in the section command.

1 - Perform design at ends and 1/12th section locations along member length.

CB 1.0 Greater than 0.0 and less than 2.5,Value of Omega_2 (C1.13.6) to be used forcalculation

Equal to 0.0: Calculate Omega_2

CMY 1.0 1 - Do not calculate Omega-1 for local Y axis.

2 - Calculate Omega-1 for local Y axis

CMZ 1.0 1 - Do not calculate Omega-1 for local Z axis.

2 - Calculate Omega-1 for local Z axis

DFF 0 Default is 0 indicating that deflection check is not performed

DJ1 0 Start node of physical member for determining deflected pattern for deflection checkand should be set along with DFF parameter

DJ2 0 End node of physical member for determining deflected pattern for deflection checkand should be set along with DFF parameter

DMAX 1000 Maximum allowable depth

DMIN 0 Minimum required depth

Table 13B.1 - South African Steel Design Parameters

International Design Codes Manual — 757

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ParameterName

Default Value Description

FYLD 300Mpa Yield strength of steel

FU 345Mpa Ultimate strength of steel

KT 1.0 K value for flexural torsional buckling

KY 1.0 K value in local Y-axis, usually minor axis

KZ 1.0 K value in local Z-axis, usually major axis

LT Member length Length for flexural torsional buckling

LY Member length Length in local Y axis for slenderness value KL/r

LZ Member length Length in local Z axis for slenderness value KL/r

MAIN 0 Flag for controlling slenderness check

0 - For Check for slenderness.

1 - For Do not check for slenderness

NSF 1.0 Net section factor for tension members              

RATIO 1.0 Permissible ratio of applied load to section capacity

Used in altering the RHS of critical interaction equations

SSY 0 Sidesway parameter

0 - Sideway about local Y-axis.

1 - No sideway about local Y-axis.

SSZ 0 Sidesway parameter

0 - Sideway about local Z-axis.

1 - No sideway about local Z-axis.

TRACK 0 Track parameter

0. Print the design output at the minimum detail level.

1. Print the design output at the intermediate detail level.

2. Print the design output at maximum detail level

758— STAAD.Pro

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ParameterName

Default Value Description

UNB Member Length Unsupported length in bending compression of bottom flange for calculating momentresistance

UNT Member Length Unsupported length in bending compression of top flange for calculating momentresistance

13B.8 Code Checking

The purpose of code checking is to determine whether the current sectionproperties of the members are adequate to carry the forces obtained from the mostrecent analysis. The adequacy is checked as per the SAB0162-1: 1993requirements.

Code checking is done using forces and moments at specified sections of themembers. If the BEAM parameter for a member is set to 1 (which is also its defaultvalue), moments are calculated at every twelfth point along the beam. When nosection locations are specified and the BEAM parameter is set to zero, design will bebased on member start and end forces only. The code checking output labels themembers as PASSed or FAILed. In addition, the critical condition, governing loadcase, location (distance from the start joint) and magnitudes of the governingforces and moments are also printed. Using the TRACK parameter can control theextent of detail of the output.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Example

Sample input data for South African Code Design

PARAMETER

CODE SAB0162

MAIN 1 ALL

LY 4 MEMB 1

LZ 4 MEMB 1

UNL 4 MEMB 1

International Design Codes Manual — 759

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CB 0 MEMB 1 TO 23

CMZMEMB 2 1 TO 23

CMYMEMB 2 1 TO 23

SSY 0 MEMB 1 TO 23

SSZ 0 MEMB 1 TO 23

FU 450000 MEMB 1 TO 23

BEAM 1 ALL

NSF 0.85 ALL

KY 1.2 MEMB 3 4

RATIO 1.0 ALL

TRACK 2 ALL

FYLD 300000 1 TO 23

CHECK CODE ALL

FINISH

13B.9 Member Selection

The member selection process involves determination of the least weight memberthat PASSes the code checking procedure based on the forces and moments of themost recent analysis. The section selected will be of the same type as that specifiedinitially.

For example, a member specified initially as a channel will have a channel selectedfor it. Selection of members whose properties are originally provided from a usertable will be limited to sections in the user table. Member selection cannot beperformed on members listed as PRISMATIC. 

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

13B.10 Tabulated Results of Steel Design

Results of code checking and member selection are presented in a tabular format.The term CRITICAL COND refers to the section of the SAB0162-1: 1993specification, which governed the design.

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If the TRACK parameter is set to 1.0, the output will be displayed as follows:

**************************************STAAD.PRO CODE CHECKING

(SOUTHAFRICAN STEEL/SAB-0162-01(1993))**************************************

ALL UNITS ARE - KNS MET (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 ST 406X67UB (SOUTHAFRICAN SECTIONS)PASS SAB-13.8 0.543 10.00 0.00 -191.90

4.08|---------------------------------------------------------------------|| FACTORED RESISTANCES FOR MEMBER- 1 UNIT - KN,M PHI = 0.90|| MRZ= 353.27 MRY= 63.99|| CR= 453.21 TR= 2308.50 VR= 642.00||---------------------------------------------------------------------|

Factored member resistances will be printed out. Following is a description of someof the items printed out.

Output Term Description

MRZ Factored moment of resistance in z direction 

MRY Factored moment of resistance in y direction 

CR Factored compressive resistance for column

TR Factored tensile capacity

VR Factored shear resistance

Further details can be obtained by setting TRACK to 2.0. A typical output of track2.0 parameter is as follows.

**************************************STAAD.PRO CODE CHECKING

(SOUTHAFRICAN STEEL/SAB-0162-01(1993))**************************************

ALL UNITS ARE - KNS MET (UNLESS OTHERWISE NOTED)

International Design Codes Manual — 761

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MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 ST 406X67UB (SOUTHAFRICAN SECTIONS)PASS SAB-13.8 0.543 10.00 0.00 -191.90

4.08

MEMBER PROPERTIES (UNIT = CM)-----------------------------

CROSS SECTION AREA = 8.55E+01 MEMBER LENGTH = 7.00E+02IZ = 2.43E+04 SZ = 1.19E+03 PZ = 1.35E+03IY = 1.36E+03 SY = 1.52E+02 PY = 2.37E+02

MATERIAL PROPERTIES (UNIT = MPA)--------------------------------

FYLD = 300.0 FU = 345.0

SECTION CAPACITIES (UNIT - KN,M)---------------------------------

CRY = 4.532E+02 CRZ = 2.016E+03CTORFLX = 4.532E+02TENSILE CAPACITY = 2.308E+03 COMPRESSIVE CAPACITY =

4.532E+02FACTORED MOMENT RESISTANCE : MRY = 6.399E+01 MRZ = 3.533E+02FACTORED SHEAR RESISTANCE : VRY = 6.420E+02 VRZ = 6.075E+02

MISCELLANEOUS INFORMATION--------------------------

NET SECTION FACTOR FOR TENSION = 85.000KL/RY = 175.514 KL/RZ = 41.522 ALLOWABLE KL/R = 300.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) = 4.000OMEGA-1 (Y-AXIS) = 1.00 OMEGA-1 (Z-AXIS) = 1.00 OMEGA-2 = 1.75SHEAR FORCE (KNS) : Y AXIS = -6.305E+01 Z AXIS = 0.000E+00SLENDERNESS RATIO OF WEB (H/W) = 4.33E+01

Following is a description of some of the items printed out.

Output Term Description

CRY Factored compressive resistance for column buckling about the local y

axis

CRZ Factored compressive resistance for column buckling about the local z

axis

CTORFLX Factored compressive resistance against torsional flexural buckling

TENSILE CAPACITY Factored tensile capacity

762— STAAD.Pro

South African Codes - Steel Design Per SAB Standard SAB0162-1:1993

Page 773: International Codes v8i

Output Term Description

COMPRESSIVE

CAPACITY

Factored compressive capacity

FACTORED MOMENT

RESISTANCE

MRY = Factored moment of resistance in y direction

MRZ = Factored moment of resistance in z direction

FACTORED SHEAR

RESISTANCE

VRY = Factored shear resistance in y direction

VRZ = Factored shear resistance in z direction

13B.11 Verification Problems

In the next few pages are included three verification examples for referencepurposes.

13B.11 Verification Problem No. 1

Determine the capacity of a South African I-section column in axial compression perSouth African steel design code (SAB:0162-1(1993)) . Column is braced at its endsfor both axes.

Reference

Example 4.3.4.1, page 4.18, Structural Steel Design to SAB:0162-1(1993)(Limitstate Design) by Greg Parrott, 1st edition, Shades Technical publication

Given

FYLD = 300 Mpa            

Length = 6000 mm

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Comparison

Source Axial Compressive Strength(kN)

Reference 1516

STAAD.Pro 1516

Difference None

Table 13B.2 - SAB0162-1:1993 Verification Prob-lem 1

Input File

STAAD PLANE

START JOB INFORMATION

ENGINEER DATE

END JOB INFORMATION

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 6 0;

MEMBER INCIDENCES

1 1 2;

MEMBER PROPERTY SAFRICAN

1 TABLE ST 356X67UB

DEFINEMATERIAL START

ISOTROPIC STEEL

E 1.99947E+008

POISSON 0.3

DENSITY 76.8191

ALPHA 6E-006

DAMP 0.03

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TYPE STEEL

STRENGTH FY 248210 FU 399894 RY 1.5 RT 1.2

END DEFINEMATERIAL

UNIT MMS KN

CONSTANTS

MATERIAL STEEL ALL

UNIT METER KN

SUPPORTS

1 FIXED

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

JOINT LOAD

2 FY -1500

PERFORMANALYSIS

PARAMETER 1

CODE SABS0162

LZ 6 ALL

LY 3 ALL

FU 450000 ALL

BEAM 1 ALL

NSF 0.85 ALL

TRACK 2 ALL

FYLD 300000 ALL

CHECK CODE ALL

FINISH

Output

(SOUTHAFRICAN STEEL/SAB-0162-01(1993))**************************************

ALL UNITS ARE - KNS MET (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/FX MY MZ LOCATION

=======================================================================

International Design Codes Manual — 765

Page 776: International Codes v8i

1 ST 356X67UB (SOUTHAFRICAN SECTIONS)PASS COMPRESSION 0.989 1

1500.00 0.00 0.00 0.00

MEMBER PROPERTIES (UNIT = CM)-----------------------------

CROSS SECTION AREA = 8.55E+01 MEMBER LENGTH = 6.00E+02IZ = 1.95E+04 SZ = 1.07E+03 PZ = 1.21E+03IY = 1.36E+03 SY = 1.57E+02 PY = 2.43E+02

MATERIAL PROPERTIES (UNIT = MPA)--------------------------------

FYLD = 300.0 FU = 345.0

SECTION CAPACITIES (UNIT - KN,M)---------------------------------

CRY = 1.516E+03 CRZ = 2.038E+03CTORFLX = 1.516E+03TENSILE CAPACITY = 1.918E+03 COMPRESSIVE CAPACITY = 1.516E+03FACTORED MOMENT RESISTANCE : MRY = 6.561E+01 MRZ = 1.991E+02FACTORED SHEAR RESISTANCE : VRY = 5.903E+02 VRZ = 6.461E+02

MISCELLANEOUS INFORMATION--------------------------

NET SECTION FACTOR FOR TENSION = 0.850KL/RY = 75.220 KL/RZ = 39.730 ALLOWABLE KL/R = 200.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) = 6.000OMEGA-1 (Y-AXIS) = 1.00 OMEGA-1 (Z-AXIS) = 1.00 OMEGA-2 = 1.00SHEAR FORCE (KNS) : Y AXIS = 0.000E+00 Z AXIS = 0.000E+00SLENDERNESS RATIO OF WEB (H/W) = 3.65E+01

13B.11 Verification Problem No. 2

Determine the capacity of a South African I-section beam in bending per SouthAfrican steel design code (SAB:0162-1(1993)). The beam has torsional and simplelateral rotational restraint at the supports, and the applied point load provideseffective lateral restraint at the point of application is braced at its ends for bothaxes.       

Reference

Example 4.5, page 4.37, Structural Steel Design to SAB:0162-1(1993)(Limit stateDesign) by Greg Parrott, 1st edition, Shades Technical publication

Given

FYLD = 300 Mpa

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Comparison

Source Major Axis Bending Resistance(kN)

Reference 353.4

STAAD.Pro 353.3

Difference Negligible

Table 13B.3 - SAB0162-1:1993 Verification Prob-lem 2

Input File

STAAD PLANE

START JOB INFORMATION

ENGINEER DATE

END JOB INFORMATION

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 10 0 0; 3 7 0 0

MEMBER INCIDENCES

1 1 3; 2 3 2

MEMBER PROPERTY SAFRICAN

1 2 TABLE ST 406X67UB

DEFINEMATERIAL START

ISOTROPIC MATERIAL1

E 2.00E+008

POISSON 3

DENSITY 977

ISOTROPIC STEEL

E 2.00E+008

International Design Codes Manual — 767

Page 778: International Codes v8i

POISSON 3

DENSITY 8195

ALPHA 2E-005

DAMP 03

END DEFINEMATERIAL

UNIT MMS KN

CONSTANTS

MATERIAL STEELMEMB 1 2

UNIT METER KN

SUPPORTS

1 3 PINNED

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

MEMBER LOAD

1 CON GY -104 4

1 UNIGY -4

2 UNIGY -2

PERFORMANALYSIS

PARAMETER

CODE SABS0162

CB 0 ALL

UNL 4 MEMB 1

FU 450000 ALL

BEAM 1 ALL

NSF 85 ALL

FYLD 300000 ALL

TRACK 2 ALL

CHECK CODEMEMB 1

FINISH

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Output

**************************************STAAD.PRO CODE CHECKING

(SOUTHAFRICAN STEEL/SAB-0162-01(1993))**************************************

ALL UNITS ARE - KNS MET (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/FX MY MZ LOCATION

=======================================================================

1 ST 406X67UB (SOUTHAFRICAN SECTIONS)PASS SAB-13.8 0.543 10.00 0.00 -191.90 4.08

MEMBER PROPERTIES (UNIT = CM)-----------------------------

CROSS SECTION AREA = 8.55E+01 MEMBER LENGTH = 7.00E+02IZ = 2.43E+04 SZ = 1.19E+03 PZ = 1.35E+03IY = 1.36E+03 SY = 1.52E+02 PY = 2.37E+02

MATERIAL PROPERTIES (UNIT = MPA)--------------------------------

FYLD = 300.0 FU = 345.0

SECTION CAPACITIES (UNIT - KN,M)---------------------------------

CRY = 4.532E+02 CRZ = 2.016E+03CTORFLX = 4.532E+02TENSILE CAPACITY = 2.308E+03 COMPRESSIVE CAPACITY = 4.532E+02FACTORED MOMENT RESISTANCE : MRY = 6.399E+01 MRZ = 3.533E+02FACTORED SHEAR RESISTANCE : VRY = 6.420E+02 VRZ = 6.075E+02

MISCELLANEOUS INFORMATION--------------------------

NET SECTION FACTOR FOR TENSION = 85.000KL/RY = 175.514 KL/RZ = 41.522 ALLOWABLE KL/R = 300.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) = 4.000OMEGA-1 (Y-AXIS) = 1.00 OMEGA-1 (Z-AXIS) = 1.00 OMEGA-2 = 1.75SHEAR FORCE (KNS) : Y AXIS = -6.305E+01 Z AXIS = 0.000E+00SLENDERNESS RATIO OF WEB (H/W) = 4.33E+01

13B.11 Verification Problem No. 3

Determine the elastic shear capacity per South African steel design code(SAB:0162-1(1993)) of a South African I-section which is simply supported overthe span of 8 m.

International Design Codes Manual — 769

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Reference

Example 4.6.5, page 4.54, Structural Steel Design to SAB:0162-1(1993)(Limitstate Design) by Greg Parrott, 1st edition, Shades Technical publication

Given

FYLD = 300 Mpa

Comparison

Source Shear Capacity (kN)

Reference 687.1

STAAD.Pro 687.1

Difference None

Table 13B.4 - SAB0162-1:1993 Verification Prob-lem 3

Input File

STAAD PLANE

START JOB INFORMATION

ENGINEER DATE

END JOB INFORMATION

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 8 0 0

MEMBER INCIDENCES

1 1 2

MEMBER PROPERTY SAFRICAN

1 TABLE ST 457X67UB

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Page 781: International Codes v8i

DEFINEMATERIAL START

ISOTROPIC MATERIAL1

E 2E+008

POISSON 3

DENSITY 977

ISOTROPIC STEEL

E 2E+008

POISSON 3

DENSITY 8195

ALPHA 2E-005

DAMP 03

END DEFINEMATERIAL

UNIT MMS KN

CONSTANTS

MATERIAL STEELMEMB 1

UNIT METER KN

SUPPORTS

1 2 PINNED

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

MEMBER LOAD

1 UNIGY -70

PERFORMANALYSIS

PARAMETER

CODE SABS0162

FU 450000 ALL

BEAM 1 ALL

FYLD 300000 ALL

TRACK 2 ALL

CHECK CODE ALL

FINISH

International Design Codes Manual — 771

Page 782: International Codes v8i

Output

**************************************STAAD.PRO CODE CHECKING

(SOUTHAFRICAN STEEL/SAB-0162-01(1993))**************************************

ALL UNITS ARE - KNS MET (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/FX MY MZ LOCATION

=======================================================================

* 1 ST 457X67UB (SOUTHAFRICAN SECTIONS)FAIL SAB-13.8 4.134 10.00 0.00 -560.00 4.00

MEMBER PROPERTIES (UNIT = CM)-----------------------------

CROSS SECTION AREA = 8.55E+01 MEMBER LENGTH = 8.00E+02IZ = 2.94E+04 SZ = 1.30E+03 PZ = 1.47E+03IY = 1.45E+03 SY = 1.53E+02 PY = 2.37E+02

MATERIAL PROPERTIES (UNIT = MPA)--------------------------------

FYLD = 300.0 FU = 345.0

SECTION CAPACITIES (UNIT - KN,M)---------------------------------

CRY = 3.738E+02 CRZ = 1.996E+03CTORFLX = 3.738E+02TENSILE CAPACITY = 2.257E+03 COMPRESSIVE CAPACITY = 3.738E+02FACTORED MOMENT RESISTANCE : MRY = 6.399E+01 MRZ = 1.355E+02FACTORED SHEAR RESISTANCE : VRY = 6.871E+02 VRZ = 5.730E+02

MISCELLANEOUS INFORMATION--------------------------

NET SECTION FACTOR FOR TENSION = 1.000KL/RY = 194.263 KL/RZ = 43.142 ALLOWABLE KL/R = 300.000UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) = 8.000OMEGA-1 (Y-AXIS) = 1.00 OMEGA-1 (Z-AXIS) = 1.00 OMEGA-2 = 1.00SHEAR FORCE (KNS) : Y AXIS = 0.000E+00 Z AXIS = 0.000E+00SLENDERNESS RATIO OF WEB (H/W) = 5.04E+01

772— STAAD.Pro

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Section 14

American Aluminum Code

14.1 GeneralSTAAD is equipped with the facilities to perform design based on the specificationsfor Aluminum Structures. The requirements of the Allowable Stress Design, Sixthedition, October 1994, have been implemented.

The various issues related to the implementation of this code in STAAD areexplained in the next few sections.

14.2 Member PropertiesIn order to do this design in STAAD, the members in the structure must have theirproperties specified from Section VI of the above-mentioned manual. The sectionnames are mentioned in Tables 5 through 28 of that manual. All of those tablesexcept Table 10 (Wing Channels) and Table 20 (Bulb Angles) are available inSTAAD.

Described below is the command specification for various sections:

International Design Codes Manual — 773

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Standard single section

MEMB-LIST TA ST SECTION-NAME

Example:

1 TO 5 TA ST CS12X11.8

9 TA ST I8.00X13.1

11 33 45 67 TA ST LS8.00X8.00X0.625

18 TA ST 1.50PIPEX160

15 TA ST T(A-N)6.00X8.00X11.2

23 25 29 TA ST 20X12RECTX.500WALL

Double channel back-to-back

MEMB-LIST TA BACK SECTION-NAME SPACING VALUE

Example

3 TA BACK C(A-N)7X3.61 SPACING 1.5

5 TA BACK C15X17.33 SP 0.75

Double channel front-to-front

MEMB-LIST TA FRONT SECTION-NAME SPACING VALUE

Example

2 TA FRONT CS12X10.3 SP 1.0

4 TA FR CS10X10.1 SP 0.5

Double angle long leg back-to-back

MEMB-LIST TA LD SECTION-NAME SPACING VALUE

Example

774— STAAD.Pro

Page 785: International Codes v8i

14 TA LD LS4.00X3.00X0.375 SP 1.5

Double angle short leg back-to-back

MEMB-LIST TA SD SECTION-NAME SPACING VALUE

Example

12 TA SD L3.5X3X0.5 SP 0.25

13 TA SD L8X6X0.75 SP 1.0

14.3 Design ProcedureThe design is done according to the rules specified in Sections 4.1, 4.2 and 4.4 onpages I-A-41 and I-A-42 of the Aluminum code. The allowable stresses for thevarious sections are computed according to the equations shown in Section 3.4.1through 3.4.21 on pages I-A-27 through I-A-40. The adequacy of the member ischecked by calculating the value of the left-hand side of equations 4.1.1-1, 4.1.1-2,4.1.1-3, 4.1.2-1, 4.4-1 and 4.4-2. This left-hand side value is termed as RATIO. Ifthe highest RATIO among these equations turns out to be less than or equal to 1.0,the member is declared as having PASSed. If it exceeds 1.0, the member hasFAILed the design requirements.

Note: The check for torsion per Clause 4.3 for open sections is currently notimplemented in STAAD.Pro.

14.4 Design ParametersThe following are the parameters for specifying the values for variables associatedwith the design.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

International Design Codes Manual — 775

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Parameter Name DefaultValue

Description

CODE - Must be specified asALUMINUM

Design Code to follow.

See section 5.48.1 of theTechnical ReferenceManual.

ALCLAD 0 This variable can take ona value of either 0 or 1.

0  -  Materialused in thesection is notan Alclad.

1  -  Materialused in thesection is anAlclad.

ALLOY 34 This variable can take ona value from 1 through40. The default valuerepresents the alloy6061-T6.

See Table 14A.2 belowfor a list of values for thisparameter and the alloythey represent. Table3.3-1 in Section I-B ofthe Aluminumspecifications providesinformation on theproperties of the variousalloys.

Table 14A.1 - Aluminum Design Parameters

776— STAAD.Pro

Page 787: International Codes v8i

Parameter Name DefaultValue

Description

BEAM 0.0 If this parameter is set to1.0, the adequacy of themember is determined bychecking a total of 13equally spaced locationsalong the length of themember. If the BEAMvalue is 0.0, the 13location check is notconducted, and instead,checking is done only atthe locations specified bythe SECTION command(See STAAD manual fordetails). If neither theBEAM parameter nor anySECTION command isspecified, STAAD willterminate the run and askthe user to provide oneof those 2 commands.This rule is not enforcedfor TRUSS members.

DMAX 1000 in. Maximum depthpermissible for thesection during memberselection. This value mustbe provided in thecurrent units.

DMIN 0.0 in Minimum depth requiredfor the section duringmember selection. Thisvalue must be providedin the current units.

International Design Codes Manual — 777

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Parameter Name DefaultValue

Description

KT 1.0 Effective length factor fortorsional buckling. It is afraction and is unit-less.Values can range from0.01 (for a columncompletely preventedfrom torsional buckling)to any user specifiedlarge value. It is used tocompute the KL/R ratiofor twisting fordetermining theallowable stress in axialcompression.

See Equation 3.4.7.2-6on page I-A-28 of theAluminum specificationsfor details.

KY 1.0 Effective length factor foroverall column bucklingin the local Y-axis. It is afraction and is unit-less.Values can range from0.01 (for a columncompletely preventedfrom buckling) to anyuser specified largevalue. It is used tocompute the KL/R ratiofor determining theallowable stress in axialcompression.

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Parameter Name DefaultValue

Description

KZ 1.0 Effective length factor foroverall column bucklingin the local Z-axis. It is afraction and is unit-less.Values can range from0.01 (for a columncompletely preventedfrom buckling) to anyuser specified largevalue. It is used tocompute the KL/R ratiofor determining theallowable stress in axialcompression.

LT Memberlength

Unbraced length fortwisting. It is input in thecurrent units of length.Values can range from0.01 (for a columncompletely preventedfrom torsional buckling)to any user specifiedlarge value. It is used tocompute the KL/R ratiofor twisting fordetermining theallowable stress in axialcompression. SeeEquation 3.4.7.2-6 onpage I-A-28 of theAluminum specificationsfor details.

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Parameter Name DefaultValue

Description

LY Memberlength

Effective length foroverall column bucklingin the local Y-axis. It isinput in the current unitsof length. Values canrange from 0.01 (for acolumn completelyprevented from buckling)to any user specifiedlarge value. It is used tocompute the KL/R ratiofor determining theallowable stress in axialcompression.

LZ Memberlength

Effective length foroverall column bucklingin the local Z-axis. It isinput in the current unitsof length. Values canrange from 0.01 (for acolumn completelyprevented from buckling)to any user specifiedlarge value. It is used tocompute the KL/R ratiofor determining theallowable stress in axialcompression.

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Parameter Name DefaultValue

Description

PRODUCT 1 This variable can take ona value from 1 through 4.They represent:

1  -  All

2  - Extrusions

3  -  DrawnTube

4  -  Pipe

The default value standsfor All. The PRODUCTparameter finds mentionin Table 3.3-1 in SectionI-B of the Aluminumspecifications.

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Parameter Name DefaultValue

Description

SSY 0.0 Factor that indicateswhether or not thestructure is subjected tosidesway along the localY axis of the member.The values are:

0  - Sideswayis presentalong thelocal Y-axis ofthe member

1  -  There isno sideswayalong thelocal Y-axis ofthe member.

The sidesway condition isused to determine thevalue of Cm explained inSection 4.1.1, page I-A-41 of the Aluminumspecifications.

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Parameter Name DefaultValue

Description

SSZ 0.0 Factor that indicateswhether or not thestructure is subjected tosidesway along the localZ axis of the member.The values are:

0  -  Sideswayis presentalong thelocal Z-axis ofthe member

1  -  There isno sideswayalong thelocal Z-axis ofthe member.

The sidesway condition isused to determine thevalue of Cm explained inSection 4.1.1, page I-A-41 of the Aluminumspecifications.

STIFF Memberlength

Spacing in thelongitudinal direction ofshear stiffeners forstiffened flat webs. It isinput in the current unitsof length. See section3.4.21 on page I-A-40 ofthe Aluminumspecifications forinformation regardingthis parameter.

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Parameter Name DefaultValue

Description

STRUCTURE 1 In Table 3.4-1 in SectionI-A of the Aluminumspecifications, it ismentioned that the valueof coefficients nu, ny andna  are dependent uponwhether the structurebeing designed is abuilding or a bridge.Users may convey thisinformation to STAADusing the parameterSTRUCTURE. The valuesthat can be assigned tothis parameter are:

1  -  Buildingsand similartypestructures

2  -  Bridgesand similartypestructures

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Parameter Name DefaultValue

Description

TRACK 2 This parameter is used tocontrol the level of detailin which the designoutput is reported in theoutput file. The allowablevalues are:

1  -  Prints only themember number, sectionname, ratio, andPASS/FAIL status.

2  -  Prints the designsummary in addition tothat printed by TRACK 1

3  -  Prints the memberproperties and alloyproperties in addition tothat printed byTRACK 2.

4  -  Prints the values ofvariables used in designin addition to that printedby TRACK 3.

UNL Memberlength

Distance between pointswhere the compressionflange is braced againstbuckling or twisting. Thisvalue must be providedin the current units. Thisvalue is used to computethe allowable stress inbending compression.

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Parameter Name DefaultValue

Description

WELD 0 In Table 3.4-2 in SectionI-A of the Aluminumspecifications, it ismentioned that the valueof coefficients Kt and Kcare dependent uponwhether or not, thelocation of the sectionwhere design is done iswithin 1.0 inch of a weld.The WELD parameter isused in STAAD for thispurpose. The values thatcan be assigned to thisparameter are:

0 - Region isfarther than1.0in from aweld

1 - Region iswithin 1.0infrom a weld

Aluminum Alloys available in STAAD

Value Name

1 1100-H12

2 1100-H14

3 2014-T6

4 2014-T6510

5 2014-T6511

6 2014-T651

Table 14A.2 - Alloy Parameters

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Value Name

7 3003-H12

8 3003-H14

9 3003-H16

10 3003-H18

11 3004-H32

12 3004-H34

13 3004-H36

14 3004-H38

15 5005-H12

16 5005-H14

17 5005-H32

18 5005-H34

19 5050-H32

20 5050-H34

21 5052-H32

22 5052-H34

23 5083-H111

24 5086-H111

25 5086-H116

26 5086-H32

27 5086-H34

28 5454-H111

29 5454-H112

30 5456-H111

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Value Name

31 5456-H112

32 6005-T5

33 6105-T5

34 6061-T6

35 6061-T6510

36 6061-T6511

37 6061-T651

38 6063-T5

39 6063-T6

40 6351-T5

14.5 Code CheckingThe purpose of code checking is to determine whether the initially specifiedmember properties are adequate to carry the forces transmitted to the memberdue to the loads on the structure. Code checking is done at the locations specifiedby either the SECTION command or the BEAM parameter described above.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Example Problem 1 in the Getting Started and Tutorials Manual for STAADprovides an example on the usage of the CHECK CODE command.

Example

Sample input data for Aluminum Design

PARAMETER

CODE ALUMINUM

BEAM1 ALL

KY 1.2 MEMB 3 4

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ALLOY 35 ALL

PRODUCT 2 ALL

TRACK 3 ALL

SELECT ALL

ALCLAD 1 ALL

STRUCT 1 ALL

CHECK CODE ALL

14.6 Member SelectionThe member selection process involves the determination of the least weightmember that PASSes the code checking procedure based on the forces andmoments of the most recent analysis. The section selected will be of the same typeas that specified initially. For example, a member specified initially as a channel willhave a channel selected for it.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

Example Problem 1 in the Getting Started and Tutorials Manual for STAAD providesan example on the usage of the SELECT MEMBER command.

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Section 15

American TransmissionTower Code

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American Transmission Tower Code - SteelDesign per ASCE 10-97

15A.1 General  Comments

The design of structural steel members in accordance with the specifications ofASCE Standard 10-97 – Design of Latticed Steel Transmission Structures is nowimplemented. This code is meant to supercede the older edition of the code,available under the name ASCE Publication 52. However, in the interests ofbackward compatibility, both codes are currently accessible in STAAD.Pro.

To access the ASCE 52 code, use the commands

PARAMETER

CODE ASCE 52

To access the ASCE 10-97 code, use the commands

PARAMETER

CODE ASCE

In general, the concepts followed in MEMBER SELECTION and CODE CHECKINGprocedures are similar to that of the AISC based design.  It is assumed that the useris familiar with the basic concepts of steel design facilities available in STAAD. Please refer to Section 2 of the STAAD Technical Reference Manual for detailedinformation on this topic.  This section specifically addresses the implementation ofsteel design based on ASCE 10-97.

Design is available for all standard sections listed in the AISC ASD 9th editionmanual, namely, Wide Flanges, S, M, HP, Tees, Channels, Single Angles, DoubleAngles, Tubes and Pipes. Design of HSS sections (those listed in the 3rd editionAISC LRFD manual) and Composite beams (I shapes with concrete slab on top) isnot supported.

15A.2 Allowable  Stresses  per  ASCE  10 - 97

Member selection and code checking operations in the STAAD implementation ofASCE 10-97 are done to resist loads at stresses approaching yielding, buckling,fracture and other limiting conditions specified in the standard. Those stresses are

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referred to in the standard as Design Stresses. The appropriate sections of theASCE standard where the procedure for calculating the design stresses isexplained are as follows.

Design Axial Tensile Stress

Design tensile stresses are calculated on the basis of the procedure described insection 3.10. The NSF parameter (see the Parameters table shown later in thissection) may be used if the section area needs to be reduced to account for boltholes. 

Design Axial Compressive Stress

Design compressive stress calculation is based on the procedures of section 3.6through 3.9.  For angle members under compression, the procedures of sections3.7 and 3.8 have been implemented. Capacity of the section is computed forcolumn buckling and wherever applicable, torsional buckling. The user maycontrol the effective lengths for buckling using the LT, LY, LZ and/or KT, KY, KZparameters (see the Parameters table shown later in this section).

Design Bending Compressive Stress

Calculations for design bending compressive stress about the major axis andminor axis are based on the procedures of section 3.14.  Procedures outlined insections 3.14.1 through 3.14.6 have been implemented.

Design Bending Tensile Stress

Calculations for design bending tensile stress about the major and minor axis arebased on the procedures of section 3.14.2.

Design Shear Stress

Calculation of the design shear stress is based on the procedure outlined in section3.15 of the ASCE 10-97. The procedure of section 3.15.2 is followed for anglesand the procedure of section 3.15.1 is followed for all other sections.

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15A.3   Critical Conditions used as criteria to deter-mine Pass/Fail status

These are Clause 3.4 for slenderness limits, Clause 3.12 for Axial Compression andBending, Clause 3.13 for Axial Tension and Bending, Clause 3.9.2 for Maximum w/tratios and Clause 3.15 for Shear.

15A.4 Design Parameters

Design per ASCE (10-97) must be initiated by using the command CODE ASCE. Thiscommand should be the first command after the PARAMETER statement.  Otherapplicable parameters are summarized in the table shown later in this section. These parameters may be used to control the design process to suit specificmodeling needs.  The default parameter values have been selected such that theyare frequently used numbers for conventional design.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

DefaultValue

Description

CODE - Must be specified as ASCE to designper ASCE 10-97.

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM 1.0 0 =  Perform design at beam endsand section locations specifiedaccording to the SECTIONcommand

1 =   Perform design at the endsand eleven intermediate sections ofthe beam

Table 15A.1 - Steel Design Parameters for ASCE 10-97

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ParameterName

DefaultValue

Description

CMY

CMZ

0.85 forsideswayand

calculatedfor nosidesway

Cm value in local y and z axes asdefined in equation 3.12-1 on p.10of ASCE 10-97.

DMAX 45.0 in. Maximum allowable depth formember selection

DBL 0.75 in. Diameter of bolt for calculation ofnumber of bolts required and thenet section factor.

DMIN 0.0 in. Minimum allowable depth formember selection

ELA 4 Indicates what type of endconditions are to be used fromamong Equations 3.7-4 thru 3.7-7to determine the KL/R ratio.

1. EQN.3.7-4, Page 4 (VALIDFOR LEG MEMBERS ONLY)

2. EQN.3.7-5, Page 4

3. EQN.3.7-6, Page 4

4. EQN.3.7-7, Page 5

ELB 1 Indicates what type of endconditions are to be used fromamong Equations. 3.7-8 thru 3.7-10 and 3.7-12 thru 3.7-14 todetermine the KL/R ratio.

1. EQN.3.7-8, Page 5, EQN.3.7-12, Page 5

2. EQN.3.7-9, Page 5, EQN.3.7-13, Page 5

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ParameterName

DefaultValue

Description

3. EQN.3.7-10, Page 5,EQN.3.7-14,Page 5

FVB 30 KSI Shear strength of bolt.

FYB 36 KSI Yield strength of bolt.

FYLD 36.0 KSI Yield Strength of steel

KT 1.0 Effective length coefficient forwarping restraint (clause 3.14.4,pg 11)

KY 1.0 Effective length factor (K) forcompression buckling about the Y-axis (minor axis)

KZ 1.0 Effective length factor (K) forcompression buckling about the Z-axis (major axis)

LEG 0.0 This parameter is meant for plainangles.

0. indicates that the angle is con-nected by both legs and allow-able stress in axial tension is1.0FYLD. 

1. indicates that the angle is con-nected only by the shorter legand allowable tensile stress iscomputed per clause 3.10.2as 0.9FYLD.

2. indicates that the angle is con-nected by the longer leg.

LT MemberLength

Effective length for warping.

LY MemberLength

Length to calculate slendernessratio for buckling about the Y-axis

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ParameterName

DefaultValue

Description

(minor axis)

LZ MemberLength

Length to calculate slendernessratio for buckling about the Z-axis(major axis)

MAIN 2 Parameter that indicates themember type for the purpose ofcalculating the KL/R ratio  (SEECLAUSE 3.4, PAGE 3, ASCE 10-97)

1. Leg member, KL/R <= 150 

2. Compression member, KL/R<= 200

3. Tension member, KL/R <=500

4. Hanger member, KL/R <=375  (Clause 4C.4, page 43)

5. Redundant member, KL/R <=250

10. Do not perform the KL/RCheck

NHL 0 Number of bolt holes on the crosssection that should be used todetermine the net section factor fortension capacity.

NSF 1.0 Net section factor for tensionmembers

RATIO 1.0 Permissible ratio that determinesthe cut off point for pass/fail status.A value below this quantity indicates PASS while a valuegreater than this quantity indicatesFAILURE.

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ParameterName

DefaultValue

Description

SSY 0.0 0.0 = Sidesway in local y-axis

1.0 = No sidesway

SSZ 0.0 Same as above except in local z-axis

TRACK 0.0 0.0 =  Suppresses printing ofallowable stresses

1.0  =  Prints all allowable stresses

UNB MemberLength

Unsupported length of the bottomflange for calculating flexuralstrength. Will be used only if flex-ural compression is on the bottomflange.

UNF 1.0 Same as UNL, but provided as afraction of the member length

UNL MemberLength

Unsupported length of member forcalculation of

allowable bending stress

UNT MemberLength

Unsupported length of the topflange for calculating flexuralstrength. Will be used only if flex-ural compression is on the topflange.

Note: All values must be provided in the current unit system.

15A.5 Code  Checking  and  Member  Selection

Both code checking and member selection options are available in the ASCE 10-97implementation. 

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Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

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American Transmission Tower Code - SteelDesign per ASCE Manuals and Reports

15B.1 General Comments

This document presents some general statements regarding the implementation ofthe Steel Design per ASCE Manuals and Reports on Engineering Practice No. 52 –Guide for Design of Steel Transmission Towers, Second Edition. The designphilosophy and procedural logistics for member selection and code checking isbased upon the principles of allowable stress design. Two major failure modes arerecognized: failure by overstressing and failure by stability considerations. 

The following sections describe the salient features regarding the process ofcalculation of the relevant allowable stresses and the stability criteria being used.Members are proportioned to resist the design loads without exceeding theallowable stresses and the most economical section is selected based on the leastweight criteria.  The code checking part of the program also checks the slendernessrequirements, the minimummetal thickness requirements and the width-thicknessrequirements.  It is generally assumed that the user will take care of the detailingrequirements like provision of stiffeners and check the local effects like flangebuckling, web crippling, etc.  It general, it may be noted that the concepts followedin MEMBER SELECTION and CODE CHECKING procedures are similar to that of theAISC based design.  It is assumed that the user is familiar with the basic concepts ofSteel Design facilities available in STAAD.  Please refer to Section 3 of the STAADTechnical Reference Manual for detailed information on this topic.  This documentspecifically addresses the implementation of steel design based on ASCE Pub. 52.

15B.2 Allowable Stresses per ASCE (Pub. 52)

The member design and code checking in the STAAD implementation of ASCE(Pub. 52) is based upon the allowable stress design method. Appropriate sectionsof this publication are referenced below.

Allowable Axial Tensile Stress

Allowable tensile stresses are calculated on the basis of the procedure described insection 4.10. The NSF parameter (Table 1.1) may be used if the net section areaneeds to be used.

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Allowable Axial Compressive Stress

Allowable compressive stress calculation is based on the procedures of section 4.6through 4.9. For angle members under compression, the procedures of sections4.7 and 4.8 have been implemented. Capacity of the section is computed forcolumn buckling and wherever applicable, torsional buckling. The user maycontrol the effective lengths for buckling using the LX, LY, LZ and/or KX, KY, KZparameters (Table 1.1). 

Allowable Bending Compressive Stress

Calculations for allowable bending compressive stress about the major axis andminor axis are based on the procedures of section 4.14. Procedures outlined insections 4.14.1 through 4.14.6 have been implemented.

Allowable Bending Tensile Stress

Calculations for allowable bending tensile stress about the major and minor axisare based on the procedures of Section 4.14.2.

Allowable Shear Stress

Calculation of the allowable shear stress is based on the procedure outlined insection 4.15 of the ASCE Pub. 52. The procedure of section 4.15.2 is followed forangles and the procedure of section 4.15.1 is followed for all other sections.

Critical Conditions used as criteria to determine Pass/Fail status

These are Clause 4.4 for slenderness limits, Equation 4.12-1 for AxialCompression and Bending, Equation 4.13-1 for Axial Tension and Bending, Clause4.9.2 for Maximum w/t ratios and Clause 4.15 for Shear.

15B.3 Design  Parameters

Design per ASCE (Pub. 52) must be initiated by using the command CODE ASCE52. This command should be the first command after the PARAMETER statement. Other applicable parameters are summarized in Table 15A.1.  These parametersmay be used to control the design process to suit specific modeling needs.  The

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default parameter values have been selected such that they are frequently usednumbers for conventional design. 

15B.4 Code  Checking  and  Member  Selection

Both code checking and member selection options are available in the ASCE Pub.52 implementation. 

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

15B.5 Parameter  Definition  Table

ParameterName

DefaultValue

Description

KY 1.0 Effective length factor (K) for compressionbuckling about the Y-axis (minor axis)

KZ 1.0 Effective length factor (K) for compressionbuckling about the Z-axis (major axis)

KT 1.0 Effective length coefficient for warpingrestraint (clause 4.14.4, pg 36)

LY MemberLength

Length to calculate slenderness ratio forbuckling about the Y-axis (minor axis)

LZ MemberLength

Length to calculate slenderness ratio forbuckling about the Z-axis (major axis)

LT MemberLength

Effective length for warping.

FYLD 36.0 KSI Yield Strength of steelNSF 1.0 Net section factor for tension membersUNL Member

LengthUnsupported length of member for

calculation of

allowable bending stress

Table 15B.1 - Steel Design Parameters for ASCE (Pub. 52) BasedDesign

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ParameterName

DefaultValue

Description

UNF 1.0 Same as UNL, but provided as a fraction ofthe member length

TRACK 0.0 0.0 =  Suppresses printing of allowablestresses 

1.0  =  Prints all allowable stressesDMAX 45.0 in. Maximum allowable depth for member

selectionDMIN 0.0 in. Minimum allowable depth for member

selectionRATIO 1.0 Permissible ratio that determines the cut

off point for

pass/fail status. A value below thisquantity 

indicates PASS while a value greater thanthis

quantity indicates FAILURE.BEAM 0.0 2.0 =  Perform design using the section

locations specified according to the SECTIONcommand

3.0 =  Perform design at the ends andeleven intermediate sections of the beam

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ParameterName

DefaultValue

Description

MAIN 2 Parameter that indicates the member typefor the purpose of calculating the KL/R

ratio 

(SEE CLAUSE 4.4, PAGE 25)

=  10 : DO NOT PERFORM THE KL/RCHECK

=   1 : LEG MEMBER          KL/R <= 150 

=   2 : COMPRESSION MEMBER  KL/R <=200

=   3 : TENSION MEMBER      KL/R <= 500

=   4 : HANGAR MEMBERS      KL/R <=375 

(Clause 4C.4, page 43)

=  5 : REDUNDANT MEMBERS     KL/R <=250

ELA 4 Indicates what type of end conditions areto be used

From among Equations 4.7-4 thru 4.7-7to determine the

the KL/R ratio.

ELA=1 :  EQN.4.7-4, Page 26

(VALID FOR LEG MEMBERS ONLY)

ELA=2 :  EQN.4.7-5, Page 27

ELA=3 :  EQN.4.7-6, Page 27

ELA=4 :  EQN.4.7-7, Page 27

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ParameterName

DefaultValue

Description

ELB 1 Indicates what type of end conditions areto be used from among Equations. 4.7-8thru 4.7-10 to determine the KL/R ratio.

ELB=1 : EQN.4.7-8, Page 27, EQN.4.7-12, Page 28

ELB=2 : EQN.4.7-9, Page 27, EQN.4.7-13, Page 28

ELB=3 : EQN.4.7-10, Page 27, EQN.4.7-14,Page28

LEG 0.0 This parameter is meant for plain angles.

3.0 =  indicates that the angle isconnected by both legs and allowable stress in

axial tension is 1.0 FYLD. 

4.0 =  indicates that the angle isconnected only by the shorter leg and allowabletensile stress is computed per clause 4.10.2 as

0.9FYLD.

5.0 =  indicates that the angle isconnected by the longer leg.

DBL 0.75 in. Diameter of bolt for calculation of numberof bolts required and the net section factor.

FYB 36 KSI Yield strength of bolt.FVB 30 KSI Shear strength of bolt.NHL 0 Number of bolt holes on the cross section

that should be used to determine the net sectionfactor for tension capacity.

Notes:

l All values must be provided in the current unit system.

l Once a parameter is specified, its value stays at that specified number till it isspecified again. This is the way STAAD works for all codes.

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Section 16

Steel Design per AmericanPetroleum Institute Code

The API Steel Design facility in STAAD is based on the API 2A-WSD standard, titled"Recommended Practice for Planning, Design and Constructing Fixed OffshorePlatforms-Working Stress Design," 21st Edition.

16.1 Design Operations STAAD contains a broad set of facilities for the design of structural members asindividual components of an analyzed structure.  The member design facilitiesprovide the user with the ability to carry out a number of different designoperations.  These facilities may be used selectively in accordance with therequirements of the design problem.  The operations to perform a design are:

l Specify the members and the load cases to be considered in the design;

l Specify whether to perform code checking or member selection;

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l Specify design parameter values, if different from the default values; and

l Specify design parameters to carry out punching shear checks.

These operations may be repeated by the user any number of times dependingupon the design requirements, but care should be taken when coupled withmanipulation of the punching shear LEG parameter.

The basic process is as follows:

1. Define the STAAD model geometry, loading and analysis.

2. Define the API code parameters with LEG 1.0.

3. Run the analysis and API design which creates the Geometry file and givepreliminary design results.

4. Check and modify the Geometry file as necessary.

5. Reset the LEG parameter to 2.0 and re-run the analysis to read the modifiedGeometry file for the final design results.

16.2 Allowables per API  CodeFor steel design, STAAD compares the actual stresses with the allowable stressesas defined by the American Petroleum Institute (API-RP2A) Code.  The 21stedition of API Code, as published in 2007, is used as the basis of this design(except for tension stress). 

16.2.1 Tension Stress

Allowable tension stresses, as calculated in STAAD, are based on the API Code,clause (3.2.1-1).

Allowable tension stress on the net section

Ft= 0.60·F

y

16.2.2   Shear  Stress

Beam Shear Stress

Allowable beam shear stress on the gross section must conform to Clause 3.2.4-2of the API code:

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Fv= 0.4·F

y

The maximum applied beam shear stress is per Eqn 3.2.4-1:

fv= V / 0.5 A

Torsional Shear Stress

Allowable torsional shear stress per Eqn. 3.2.4-4:

Fvt= 0.4·F

y

Fvtis the maximum torsional shear stress per Clause 3.2.4-3 of the API code.

16.2.3 Stress Due to Compression

The allowable compressive stress on the gross section of axially loadedcompression members is calculated based on the formula 3.2.2-1 in the API Codewhen the largest effective slenderness ratio, Kl/r is less than or equal to C

c. If Kl/r

exceeds Cc, then the allowable compressive stress is increased as per formula

(3.2.2-2) of the Code.

Where:

For D/t > 60, the lesser of Fxeor F

xcis substituted for F

xy.

Where:

Fxe= the elastic local buckling stress calculated with C, the critical

elastic buckling coefficient = 0.3 (3.2.2-3)

Fxc= the inelastic local buckling stress. (3.2.2-4)

16.2.4 Bending Stress

The allowable bending stress for tension and compression for a symmetricalmember loaded in the plane of its minor axis, as given in Clause 3.2.3 of the APIcode, is:

a. When D/t ≤ 1,500/Fy(Imperial Units),

Fb= 0.75F

y

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b. When 1,500/Fy < D/t ≤ 3,000/F

y(Imperial Units),

Fb= [0.84 - 1.74 F

yD/(Et)]F

y

c. When 3,000/Fy < D/t ≤ 300 (Imperial Units),

Fb= [0.72 - 0.58 F

yD/(Et)]F

y

16.2.5 Combined Compression and Bending

Members subjected to both axial compression and bending stresses areproportioned to satisfy API formula 3.3.1-1 and 3.3.1-2 when f

a/Fa> 0.15,

otherwise formula 3.3.1-3 applies.  It should be noted that during code checkingor member selection, if f

a/Fa> 1.0, the program does not compute the second

3.3.1-1/2.

16.6 Design ParametersThe program contains a large number of parameter names which are required toperform design and code checks.  These parameter names, with their defaultvalues, are listed in Table 16.1.  These parameters communicate design decisionsfrom the engineer to the program.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements for an analysis, some or all of these parameter values may have to bechanged to exactly model the physical structure. For example, by default the KZvalue (k value in local z-axis) of a member is set to 1.0, wile in the real structure itmay be 1.5. In that case, the KZ value in the program can be changed to 1.5, asshown in the input instruction (Section 5). Similarly, the TRACK value of a memberis set to 0.0, which means no allowable stresses of the member will be printed.

Note: Once a parameter is specified, its value stays at that specified numbertill it is specified again. This is the way STAAD works for all codes.

ParameterName

Default Value Description

CODE - Must be specified asAPI

Table 16C.1 - American (API) Steel Design Parameters

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ParameterName

Default Value Description

Design Code to follow.

See section 5.48.1 ofthe Technical ReferenceManual.

BEAM 1.0 0.0 =  design only forend moments or

those at locationsspecified by theSECTION command.

1.0 =  calculatemoments at twelfthpoints along the beam,and use the maximumMz location for design.

2.0 = Same forBEAM 1.0, butadditional check ismade at each end.

CB 1.0 Cb value as used inSection 1.5 of AISC

0.0 = Cb value to becalculated

Any other value willmean the value to beused in design

CMY

CMZ

0.85 for sideswayand calculated forno sidesway

Cm value in local y & zaxes

DMAX 0.0 Maximum allowabledepth

DMIN 0.0 Minimum allowable

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ParameterName

Default Value Description

depth

FYLD 36 KSI Yield strength of steel.

KY 1.0 K value in local y-axis.

Usually, this is minoraxis.

KZ 1.0 K value in local z-axis.

Usually, this is majoraxis.

LEG 1.0

2.0

To write out externalparameters file.

To read in the externalparameters file.

LY Member Length Length in local Y-axis tocalculate slendernessratio.

LZ Member Length Length in local Z-axis tocalculate slendernessratio.

MAIN 0.0 1.0 = Main member

2.0 = Secondarymember

NSF 1.0 Net section factor fortension members.

RATIO 1.0 Permissible ratio of theactual to allowablestresses

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ParameterName

Default Value Description

SSY 0.0 0.0 = Sidesway in localy-axis

1.0 = No sidesway

SSZ 0.0 Same as above exceptin local z-axis

TRACK 0.0 1.0 =     Print all criticalmember

stresses

100.0 =  Suppress allchecks except punchingshear

UNL Member Length Unsupported length forcalculating allowablebending stress

UNF 1.0 Same as aboveprovided as a fractionof actual memberlength

WELD 1 for closed sections

2 for open sections

Weld type, as explainedin section 3.1.1.

1. =  Welding is oneside only exceptfor wide flange ortee sections,where the web isalways assumedto be welded onboth sides.

2. = Welding isboth sides. Forclosed sectionslike pipe or tube,

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ParameterName

Default Value Description

the welding willbe only on oneside.

WSTR 0.4 X FLYD Allowable weldingstress

WMIN 1.16 in. Minimum thickness

Note: The parameters DMAX and DMIN are only used for member selection.

16.7 Code CheckingThe purpose of code checking is to ascertain whether the provided sectionproperties of the members are adequate as per API.  Code checking is done usingthe forces and moments at specific sections of the members.  If no sections arespecified, the program uses the start and end forces for code checking.

When code checking is selected, the program calculates and prints whether themembers have passed or failed the checks, the critical condition of API code (likeany of the API specifications for compression, tension, shear, etc.), the value ofthe ratio of the critical condition (overstressed for value more than 1.0 or anyother specified RATIO value), the governing load case, and the location (distancefrom the start of the number of forces in the member) where the critical conditionoccurs.

Code checking can be done with any type of steel section listed in Section 2.2,American Steel Design, of the Technical Reference manual.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

16.8 Member SelectionSTAAD is capable of performing design operations on specified members.  Oncean analysis has been performed, the program can select the most economicalsection, i.e., the lightest section which fulfills the code requirements for thespecified member.  The section selected will be of the same type section as

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originally designated for the member being designed.  Member selection can alsobe constrained by the parameters DMAX and DMIN which limits the maximum andminimum depth of the members.

Member selection can be performed with all types of hollow steel sections.

Selection of members whose properties are originally input from a user createdtable will be limited to sections in the user table.

Member selection cannot be performed on members whose section properties areinput as prismatic.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

16.9 Truss MembersA truss member is capable of carrying only axial force.  So in design, no time iswasted calculating the allowable bending or shear stresses, thus reducing designtime considerably.  Therefore, if there is any truss member in an analysis (likebracing or strut, etc.), it is wise to declare it as a truss member rather than as aregular frame member with both ends pinned.

16.10 Punching ShearFor tubular members, punching shear may be checked in accordance with theAmerican Petroleum Institute (API) RP 2A – 20th Edition Section 4.  The parameterPUNCH is used to identify joint types for each end of the member where thepunching shear check is required. The PUNCH parameter is only read in from theexternal geometry file. The external geometry file is described in section 16.13. ThePUNCH parameter is not specified within the STAAD input file ( .STD file extension).

Type of Joint andGeometry

Req. Value ofParameterPUNCH

K (overlap) 1.0

K (gap) 2.0

Table 16C.2 - Joint identification for punch-

ing shear check

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Type of Joint andGeometry

Req. Value ofParameterPUNCH

T & Y 3.0

CROSS 4.0

CROSS

(with/diaphragms)

5.0

Note: A value representing joint type and geometry must be provided forparameter PUNCH, in the external file.  On the first run where no external tableis present, LEG must equal 1.0.

16.11  Generation  of  the  Geometry  FileAutomatic selection of the chord and brace members is performed with theparameter LEG 1.0.

Two tubular members are used by the program to identify the chord member.  Thechord members must be collinear (5 degree tolerance).

The chord member must have a greater diameter and thickness than the bracemember being considered.

The punching shear check is performed on the joint treating it as a T/Y joint.  Theyield stress of the brace is used.  In the 50% strength check the brace and chordyield are assumed to be the same.

The major moment axis Mz is taken as In Plane Bending (IPB).  To change this, theparameter SWAP 1 should be used in the external geometry file.

Note: The in-plane/out-of-plane correspondence can be set by using the BETAangle.

If the punching shear cannot be performed at the joint for the member beingconsidered, a message is written to the output file <filename>.ANL.

If a punching shear check is performed with the parameter LEG 1.0 used, thenthe geometry data used to perform the check is written to the default externaloutput file APIPUN.

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The default external output/input file name can be changed by using the commandline:

CODE API <filename>.

This external output data file can be edited and used as an external input file to re-perform the check using the parameter PUNCH 1.0 to 5.0.

This external input file allows can/stub geometry data to be specified and chords tobe assigned geometry where they could not be identified in the Automaticselection.

The parameter LEG 2.0 must be used to read an external input file where thedefault name is APIPUN.

The yield strength of the brace is used in the punching shear check.  This can bechanged in the external geometry file.  The user should ensure that the correct cordmember has been selected for the check.

16.12  Chord  Selection  and  Qf Param-eterQfis a factor to account for the presence of nominal longitudinal stress in the

chord. When calculating Qffor the joints, the moments used in the chord stress

calculation will be from the computer node results and not the representativemoments underneath the brace.  If the moment varies significantly along the chord,it is more accurate to use the actual chord moment in the middle of the brace footprint.  The tests reported in Reference I[1] were performed with a constant momentalong the chord.  Thus for a local joint check, the local chord moment (under thebrace) should be used.

STAAD calculates Qfbased on the moment at the chord member.  The chord

member can be selected automatically by initial screening by the program (basedon geometry and independent of loading) or specified in the External file.

In the automatic selection of the chord two collinear members (5 degree tolerance)are used to identify the chord.  The chord is then selected from one of the twomembers based on the larger diameter then thickness or then by the minimumframing angle; for T joints the first member modeled will be selected as the chord.

You should confirm that the chord either be assigned by the program or the user isrepresentative of the local chord moment for the brace in question.

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Reference

1 Ref I: Boone, TJ. Yura, JA. and Hoadley, PW. Ultimate Strength if Tubular Joints– Chord Stress Effects, OTC 4828, 1984

16.13 External Geometry FileAn example of the external geometry file is shown below:

BRACE CHORD PUNCH D T D T GAP FYLD THETAT TW SWAP

209 211 3 17.992 0.984 12.752 0.787 0.000 50.00 0.00 0.000 0

209 210 3 17.992 0.984 12.752 0.787 0.000 50.00 0.00 0.000 0

212 202 3 17.992 0.787 12.752 0.787 0.000 50.00 0.00 0.000 0

The parameters used in the external file are defined as follows:

Parameter Name Description

PUNCH Parameter for punching shear (See Section 12.10)

BRACE Member number of brace

CHORD Member number of chord

D Chord Diameter in inches

T Chord Thickness in inches

d Brace Diameter in inches

T Brace Thickness in inches

GAP Gap in inches (must be negative for overlap K-joint)

Table 16C.3 - External File

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Parameter Name Description

FYLD Local yield strength used for joint in KIPS

THETAT Angle of through brace in overlap K-joint in Degrees

TW Used in overlap K-joint, taken as the lesser of the weld throat thickness or thickness t of the

thinner brace in inches

SWAP If parameter SWAP 0 is used then major moment Mz is taken for In Plane Bending (IPB).

SWAP 1 uses the minor moment My as the IPB.

Notes:

l For overlap K-joints, the through brace is assumed to be the same diameteras the brace being checked.

l If any of the parameters for diameter and thickness specified in the externalfile are less than that for members being checked, then the memberproperties specified in the STAAD file shall be used.

l The member diameter and thickness should be used in API equation (4.1-1);in this check it has been assumed that the yield strength of the chord andbrace members are the same.

l The geometry file name is currently limited to eight characters (4 if anextension as .TXT is used).

The overall process of performing punching shear checks consists of two steps.These steps are explained in section 16.16.

16.14  LimitationsThe parameter SELECT 1.0 should not be used while carrying out punching shearchecks.  It can be used in initial runs for member selection.

No classification of the joint is performed using the loading.

No hydrostatic checks are performed.

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16.15  Tabulated  Results  of  Steel DesignFor code checking or member selection, the program produces the results in atabulated fashion.  The items in the output table are explained as follows:

a. Member refers to the member number for which the design is performed.

b. TABLE refers to AISC steel section name which has been checked against thesteel code or has been selected.

c. RESULTS prints whether the member has PASSed or FAILed.  If the RESULTis FAIL, there will be an asterisk (*) mark on front of the member.

d. CRITICAL COND refers to the section of the AISC code which governs thedesign.

e. RATIO prints the ratio of the actual stresses to allowable stresses for thecritical condition.  Normally a value of 1.0 or less will mean the member haspassed.

f. LOADING provides the load case number which governed the design.

g. FX, MY, and MZ provide the axial force, moment in local Y-axis, and themoment in local Z-axis respectively.  Although STAAD does consider all themember forces and moments (except torsion) to perform design, only FX,MY and MZ are printed since they are the ones which are of interest, in mostcases.

h. LOCATION specifies the actual distance from the start of the member to thesection where design forces govern.

i. If the parameter TRACK is set to 1.0, the program will block out part of thetable and will print the allowable bending stressed in compression (FCY &FCZ) and tension (FTY & FTZ), allowable axial stress in compression (FA),and allowable shear stress (FV).

16.16 The Two-Step ProcessThe overall procedure for performing the code check per the API code is asfollows:

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Step 1

Creating the geometry data file. This is done by specifying the name of thegeometry data file alongside the command line CODE API. If a file name is notspecified, STAAD automatically assigns the file name APIPUN to the geometry datafile. The parameter instructions in the .STD file should contain the LEG parameterand it should be assigned the value 1.0.

Example Reading External Geometry File

UNIT INCHES KIPS

PARAMETERS

* ALL JOINT DATAWILL BEWRITTEN TOEXTERNAL FILE GEOM1FOR PUNCHING SHEAR.

CODE API GEOM1

LEG 1.0

* JOINTS TOBE CONSIDERED AS T AND Y, I.E., PUNCH IS SET TO3.0.

FYLD 50.0 ALL

TRACK 1.0 ALL

RATIO 1.0 ALL

BEAM 1.0 ALL

CHECK CODE ALL

After ensuring that your STAAD input file contains the above data, run the analysis.Once the analysis is completed, you will find that a file by the name GEOM1 hasbeen created and is located in the same folder as the one where your .std file islocated. (In case you did not specify a file name - GEOM1 shown in the earlierexample -  STAAD will create the file named APIPUN.

Step 2

The geometry data file (GEOM 1 or otherwise) should be inspected and modified asrequired such as changing the PUNCH values and local section properties for thepunching shear checks.

Modify the .STD file so it reruns the code check process by reading the instructionsof the GEOM file. This message is conveyed by changing the value of the LEG

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parameter to 2.0. After making this change, a re-analysis will result in the programusing the information in the geometry data file (GEOM1, APIPUN, or otherwise) forperforming the code check.

Example Reading an existing Joint Geometry Data File, GEOM1

UNIT INCHES KIPS

PARAMETERS

* ALL JOINT DATAWILL BE READ FROMTHE EXTERNAL FILEGEOM1 FOR PUNCHING SHEAR.

CODE API GEOM1

LEG 2.0

FYLD 50.0 ALL

TRACK 1.0 ALL

RATIO 1.0 ALL

BEAM 1.0 ALL

CHECK CODE ALL

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Section 17

ANSI/AISC N690 DesignCodes

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ANSI/AISC N690-1994 Code17A.1 General Comments

For steel design, STAAD compares the actual stresses with the allowable stresses asdefined by ANSI/AISC N690-1994 and as amended by Supplement No. 2 to theSpecification of the Design, Fabrication and Erection of Steel Safety-RelatedStructures for Nuclear Facilities (ANSI/AISC N690 1994(R2004)s2).

All the design steps are done as described in section 2.3 Allowable per AISC-ASD(Ninth Edition) Code of Technical Reference manual except for allowable stress incompression for AUSTENlTlC STAINLESS STEEL. Section Q1.5.9 is used tocalculate allowable compressive stress for Austenitic Stainless Steel. Correctionmade in Supplementary s1 published in April 15, 2002 has been applied.

Note: By default, N690 code uses Stainless Steel material in the design. Careshould be taken to assign the proper Stainless Steel material properties to themembers for the analysis. There is a parameter – STYPE – to change materialtype to either Stainless Steel (STYPE=1) or Carbon Steel (STYPE=0).

Design ProcessMembers subjected to both axial compression and bending stresses areproportioned to satisfy equation Q1.6-1a:

SFC·fa/Fa+ SMY·C

myfby/[(1 - f

a/F'

ey)Fby] +  SMZ·C

mzfbz/[(1 - f

a/F'

ez)Fbz] ≤ 1.0

and Q1.6-1b:

SFC·fa/(0.6·F

y) + SMY·f

by/Fby+  SMZ·f

bz/Fbz≤ 1.0

when, fa/Fa> 0.15, as per section Q1.6.1 of the code.

Otherwise, equation Q1.6-2 must be satisfied:

SFC·fa/Fa+ SMY·f

by/Fby+ SMZ·f

bz/Fbz≤ 1.0

It should be noted that during code checking or member selection, if fa/Faexceeds

unity, the program does not compute the second and third part of the formula,because this would result in a misleadingly liberal ratio. The value of the coefficientCm is taken as 0.85 for side-sway and [0.6 - 0.4·(M1/M2)], but not less than 0.4 forno side-sway.

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Members subjected to both axial tension and bending stress are proportioned tosatisfy equation Q1.6-3:

SFT·fa/(0.6·F

y) + SMY·f

by/Fby+ SMZ·f

bz/Fbz≤ 1.0

Where SFC, SFT, SMZ, and SMY are stress limit coefficient parameters used tocontrol the components of the interaction equations. Refer to Table 17A.1 fordetails.

17A.2 Design Parameters

The program contains a large number of parameter names which are required toperform design and code checks. These parameter names, with their defaultvalues, are listed in the following table.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements for an analysis, some or all of these parameter values may have to bechanged to exactly model the physical structure

ParameterName

DefaultValue

Description

CODE - Must be specified as AISC N690

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM 1 Beam parameter

0. Perform design at ends andthose locations in theSECTION command.

1. Perform design at ends and at1/12th section locations alongthe member length.

CAN 0 Used for Deflection Check only (i.e.,when DFF is specified).

Table 17A.1 - Design Parameters for ANSI/AISC N690-1994

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ParameterName

DefaultValue

Description

0. Deflection check based on theprinciple that maximum deflec-tion occurs within the spanbetween DJ1 and DJ2.

1. Deflection check based on theprinciple that maximum deflec-tion is of the cantilever type

CB 1.0 Bending coefficient dependent uponmoment gradient, as specified inChapter F of AISC ASD.

0.0 = CB is calculated itself

Any other user-defined value isaccepted.

CMY

CMZ

0.85 forsideswayand

calculatedfor nosidesway

Cm value in local y & z axes

COMPOSITE 0 Composite action with connectors(CMP)

0. No composite action

1. Composite action

2. Ignore positive moments dur-ing design

CONDIA 0.625 in Diameter of shear connectors (DIA),in current units.

CONHEIGHT 2.5 in Height of shear connectors afterwelding (HGT), in current units.

CYCLES 500,000 Cycles of maximum stress to whichthe shear connector is

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ParameterName

DefaultValue

Description

subject (CYC).

DFF None(Mandatory

fordeflectioncheck)

"Deflection Length" / Maximumallowable local deflection

DJ1 Start Jointof member

Joint No. denoting starting point forcalculation of "Deflection Length"

DJ2 End Jointof member

Joint No. denoting end point forcalculation of "Deflection Length"

DLR2 0.4 Ratio of moment due to dead loadapplied after the concrete hardensto the total moment (DR2).

DLRATIO 0.4 Ratio of moment due to dead loadapplied before the concrete hardensto the total moment (DR1).

DMAX 45 inch Maximum allowable depth

DMIN 0.0 inch Minimum allowable depth

EFFWIDTH 1/4MemberLength

Effective width of concrete slab(WID).

FYLD 36 KSI Yield strength of steel in currentunits.

FPC 3 KSI Compressive strength of concrete at28 days, in current units.

FSS 1 Full section shear for welding.

0. False

1. True

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ParameterName

DefaultValue

Description

FU 60 KSI Ultimate tensile strength of steel, incurrent units.

FYLD 46 KSI Yield strength of steel, in currentunits.

KX 1.0 Effective length factor for flexuraltorsional buckling.

KY 1.0 Effective Length Factor for Com-pression in local y-axis. Usually, thisis minor axis.

KZ 1.0 Effective Length Factor for Com-pression in local z-axis. Usually, thisis major axis.

LX MemberLength

Length for flexural torsional buck-ling.

LY MemberLength

Length to calculate slendernessratio (KL/r) for buckling about localY axis.

LZ MemberLength

Same as above except in z-axis(major).

MAIN 0.0 Design for slenderness:

0. check for slenderness

1. suppress slenderness check

NSF 1.0 Net section Factor for tensionmembers

OVR 1.0 Factor by which all allowablestresses/capacities should be mul-tiplied. Default of 1.0 indicates thatno overstressing is allowed.

PLTHICK 0 Thickness of the cover plate weldedto the bottom flange of the com-

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ParameterName

DefaultValue

Description

posite beam (PLT), in current units.

PLTWIDTH 0 Width of the cover plate welded tothe bottom flange of the compositebeam (PLT), in current units.

PROFILE None Used to search for the lightestsection for the profile(s) specifiedfor member selection. See Section5.48.1 of the Technical ReferenceManual for details. 

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

RIBHEIGHT 0 Height of ribs of form steel deck(RBH), in current units.

RIBWIDTH 0 Width of ribs of form steel deck(RBW), in current units.

SFC 1.0 Stress limit coefficient for com-pression (SLC) as found in Table Q1.5.7.1.

SFT 1.0 Stress limit coefficient for tension(SLC) as found in Table Q 1.5.7.1.

SHE 0 Shear stress calculation option

0. Computes the actual shearstress using VQ/It

1. Computes the actual shearstress using V(Ay or Az)

SHORING 0 Temporary shoring duringconstruction

0. Without shoring

1. With shoring

SLABTHICK 4 in Thickness of concrete slab or thick-

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ParameterName

DefaultValue

Description

ness of concrete slab above theform steel deck (THK), in currentunits.

SMY 1.0 Stress limit coefficient for minor axisbending (SLC) as found in Table Q1.5.7.1.

SMZ 1.0 Stress limit coefficient for major axisbending (SLC) as found in Table Q1.5.7.1.

SSY 0 Design for sidesway in the local yaxis.

0. Sidesway

1. No sidesway

SSZ 0 Design for sidesway in the local zaxis.

0. Sidesway

1. No sidesway

STIFF Memberlength ordepth

whicheveris greater

Spacing of stiffeners for plate girderdesign, in current units.

STYPE 0.0 Type of steel material

0. Normal Steel

1. Austenitic Stainless Steel

TAPER 1 Design for tapered member.

0. Design for tapered I-sectionbased on rules in Chapter Fand Appendix B.

1. Design for tapered section

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ParameterName

DefaultValue

Description

based on Appendix F.

TMAIN 240 formainmember

300 for“Truss”member

Slenderness limit under tension

TORSION 0 Design for torsion.

0. Do not design for torsion.

1. Design for torsion.

TRACK 0.0 Controls the levels of detail to whichresults are reported.

0. Minimum detail

1. Intermediate detail level

2. Maximum detail

UNB MemberLength

Unsupported length of the bottom*flange for calculating allowablebending compressive stress. Will beused only if flexural compression onthe bottom flange.

UNT MemberLength

Unsupported length of the top*flange for calculating allowablebending compressive stress. Will beused only if flexural compression onthe top flange.

WELD 1 Design for weld.

0. Closed sections.

1. Open sections.

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ParameterName

DefaultValue

Description

WMAX 1 in Maximum weld thickness, in currentunits.

WMIN 0.625 in Minimum weld thickness, in currentunits.

WSTR 0.4·Fyld Allowable welding stress, in currentunits.

Notes

1. All values are entered in the current units

2. parameters DMAX and DMIN are only used with the MEMBER SELECTION com-mand

17B.3 Examples

These example problems are included for the verification of design results.

17.3.1 Example 1

Solution

Allowable Compressive Stress:

Maximum Slenderness Ratio, (Kl/r)max

= 171.31

Yield Stress of Steel, Fy= 36 ksi

Cc= [(2π2E)/F

y]1/2 = 127.68

Allowable Compressive Stress for Austentic Stainless Steel, As,

(Kl/r)max

> Cc

Fa= (12π2E)/[23(Kl/r)

max] = 5.21 ksi

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Comparison

Valueof

Reference STAAD.Pro Difference

Fa(ks) 5.21 5.22 Negligible

Table 17A.2 - ANSI-AISC N690-1994 Code Ver-ification Problem 1

Input File

This example is included as C:\SPROV8I\STAAD\EXAMP\N690\N690_CASE1.STD

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 30-NOV-07

END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 4 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 2.05E+008

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

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1 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 PINNED

2 FIXED BUT FX MYMZ

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

MEMBER LOAD

1 CON GY -10 2

UNIT METER KIP

UNIT METER KN

LOAD 2 LOADTYPE NONE TITLE LOAD CASE 2

JOINT LOAD

2 FX -1

LOAD COMB 3 COMBINATION LOAD CASE 3

1 1.0 2 9.5

PERFORMANALYSIS PRINT STATICS CHECK

PRINT ANALYSIS RESULTS

UNIT METER KIP

PARAMETER 1

CODE AISC N690

TRACK 2 ALL

CHECK CODE ALL

FINISH

Output

The corresponding TRACK 2 output is shown below:STAAD.PRO CODE CHECKING - ( ANSI N690-1994) v1.0********************************************

|--------------------------------------------------------------------------|| Y PROPERTIES |

International Design Codes Manual — 835

Page 846: International Codes v8i

|************* | IN INCH UNIT || * |=============================| ===|=== ------------ ||MEMBER 1 * | AISC SECTIONS | | AX = 3.55 || * | ST W6X12 | | --Z AY = 1.25 ||DESIGN CODE * | | | AZ = 1.50 ||ANSI N690-94* =============================== ===|=== SY = 1.50 || * SZ = 7.33 || * |<---LENGTH (FT)= 13.12 --->| RY = 0.92 ||************* RZ = 2.50 || || 7.4 (KIP-FEET) ||PARAMETER | L1 STRESSES ||IN KIP INCH | IN KIP INCH ||--------------- + L1 L1 -------------|| KL/R-Y= 171.31 | FA = 5.22 || KL/R-Z= 63.12 + L1 L1 fa = 0.60 || UNL = 157.48 | FCZ = 14.15 || CB = 1.00 + L1 L1 FTZ = 21.60 || CMY = 0.85 | L1 L1 FCY = 27.00 || CMZ = 0.85 + FTY = 27.00 || FYLD = 36.00 |L0 L0 fbz = 12.07 || NSF = 1.00 +---+---+---+---+---+---+---+---+---+---| fby = 0.00 || DFF = 0.00 -0.4 Fey = 4.65 || dff= 0.00 ABSOLUTE MZ ENVELOPE Fez = 34.26 || (KL/R)max = 171.31 (WITH LOAD NO.) FV = 14.40 || fv = 0.90 || || MAX FORCE/ MOMENT SUMMARY (KIP-FEET) || ------------------------- || || AXIAL SHEAR-Y SHEAR-Z MOMENT-Y MOMENT-Z || || VALUE 2.1 1.1 0.0 0.0 7.4 || LOCATION 0.0 0.0 0.0 0.0 6.6 || LOADING 3 1 0 0 1 || ||**************************************************************************||* *||* DESIGN SUMMARY (KIP-FEET) *||* -------------- *||* *||* RESULT/ CRITICAL COND/ RATIO/ LOADING/ *|| FX MY MZ LOCATION || ====================================================== || PASS ANSI Q1.6-2 0.968 3 || 2.14 C 0.00 -7.38 6.56 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|

836— STAAD.Pro

ANSI/AISC N690-1994 Code

Page 847: International Codes v8i

17.3.2 Example 2

Solution

Allowable Compressive Stress:

Maximum Slenderness Ratio, (Kl/r)max

= 85.65

Yield Stress of Steel, Fy= 36 ksi

Cc= [(2π2E)/F

y]1/2 = 127.68

Allowable Compressive Stress for Austentic Stainless Steel, As,

(Kl/r)max

< 120.0

Fa= (F

y/2.15) - {[(F

y/2.15) - 6.0]/120.0}x(Kl/r)

max= 9.07 ksi

Comparison

Valueof

Reference STAAD.Pro Difference

Fa(ks) 9.07 9.08 Negligible

Table 17A.3 - ANSI-AISC N690-1994 Code Ver-ification Problem 2

Input File

This example is included as C:\SPROV8I\STAAD\EXAMP\N690\N690_CASE2.STD

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 30-NOV-07

END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

International Design Codes Manual — 837

Page 848: International Codes v8i

3 0 0 1; 4 2 0 1;

MEMBER INCIDENCES

2 3 4;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 2.05E+008

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

2 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

3 PINNED

4 FIXED BUT FX MYMZ

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

MEMBER LOAD

UNIT METER KIP

2 CON GY -2.24809 1

UNIT METER KN

LOAD 2 LOADTYPE NONE TITLE LOAD CASE 2

JOINT LOAD

4 FX -1

LOAD COMB 3 COMBINATION LOAD CASE 3

1 1.0 2 9.5

PERFORMANALYSIS PRINT STATICS CHECK

PRINT ANALYSIS RESULTS

838— STAAD.Pro

ANSI/AISC N690-1994 Code

Page 849: International Codes v8i

UNIT METER KIP

PARAMETER 1

CODE AISC N690

TRACK 2 ALL

CHECK CODE ALL

FINISH

Output

The corresponding TRACK 2 output is shown below:STAAD.PRO CODE CHECKING - ( ANSI N690-1994) v1.0********************************************

|--------------------------------------------------------------------------|| Y PROPERTIES ||************* | IN INCH UNIT || * |=============================| ===|=== ------------ ||MEMBER 2 * | AISC SECTIONS | | AX = 3.55 || * | ST W6X12 | | --Z AY = 1.25 ||DESIGN CODE * | | | AZ = 1.50 ||ANSI N690-94* =============================== ===|=== SY = 1.50 || * SZ = 7.33 || * |<---LENGTH (FT)= 6.56 --->| RY = 0.92 ||************* RZ = 2.50 || || 3.7 (KIP-FEET) ||PARAMETER | L1 STRESSES ||IN KIP INCH | IN KIP INCH ||--------------- + L1 L1 -------------|| KL/R-Y= 85.65 | FA = 9.08 || KL/R-Z= 31.56 + L1 fa = 0.60 || UNL = 78.74 | L1 FCZ = 21.60 || CB = 1.00 + L1 L1 FTZ = 21.60 || CMY = 0.85 | L1 FCY = 27.00 || CMZ = 0.85 + L1 FTY = 27.00 || FYLD = 36.00 |L0 L0 fbz = 6.04 || NSF = 1.00 +---+---+---+---+---+---+---+---+---+---| fby = 0.00 || DFF = 0.00 -0.2 Fey = 18.60 || dff= 0.00 ABSOLUTE MZ ENVELOPE Fez = 137.05 || (KL/R)max = 85.65 (WITH LOAD NO.) FV = 14.40 || fv = 0.90 || || MAX FORCE/ MOMENT SUMMARY (KIP-FEET) || ------------------------- || || AXIAL SHEAR-Y SHEAR-Z MOMENT-Y MOMENT-Z || |

International Design Codes Manual — 839

Page 850: International Codes v8i

| VALUE 2.1 1.1 0.0 0.0 3.7 || LOCATION 0.0 0.0 0.0 0.0 3.3 || LOADING 3 1 0 0 1 || ||**************************************************************************||* *||* DESIGN SUMMARY (KIP-FEET) *||* -------------- *||* *||* RESULT/ CRITICAL COND/ RATIO/ LOADING/ *|| FX MY MZ LOCATION || ====================================================== || PASS ANSI Q1.6-2 0.346 3 || 2.14 C 0.00 -3.69 3.28 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|

17.3.3 Example 3

Solution

Allowable Compressive Stress:

Maximum Slenderness Ratio, (Kl/r)max

= 122.06

Yield Stress of Steel, Fy= 36 ksi

Cc= [(2π2E)/F

y]1/2 = 127.68

Allowable Compressive Stress for Austentic Stainless Steel, As,

120.0 < (Kl/r)max

< Cc

Fa= F

y[0.4 - (1/600)x(Kl/r)

max] = 7.08 ksi

Comparison

Valueof

Reference STAAD.Pro Difference

Fa(ks) 7.08 7.08 None

Table 17A.4 - ANSI-AISC N690-1994 Code Ver-ification Problem 3

840— STAAD.Pro

ANSI/AISC N690-1994 Code

Page 851: International Codes v8i

Input File

This example is included as C:\SPROV8I\STAAD\EXAMP\N690\N690_CASE3.STD

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 30-NOV-07

END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 2.85 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 2.05E+008

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

1 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 PINNED

2 FIXED BUT FX MYMZ

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

International Design Codes Manual — 841

Page 852: International Codes v8i

MEMBER LOAD

1 CON GY -10 2

UNIT METER KIP

UNIT METER KN

LOAD 2 LOADTYPE NONE TITLE LOAD CASE 2

JOINT LOAD

2 FX -1

LOAD COMB 3 COMBINATION LOAD CASE 3

1 1.0 2 9.5

PERFORMANALYSIS PRINT STATICS CHECK

PRINT ANALYSIS RESULTS

UNIT METER KIP

PARAMETER 1

CODE AISC N690

TRACK 2 ALL

CHECK CODE ALL

FINISH

Output

The corresponding TRACK 2 output is shown below:STAAD.PRO CODE CHECKING - ( ANSI N690-1994) v1.0********************************************

|--------------------------------------------------------------------------|| Y PROPERTIES ||************* | IN INCH UNIT || * |=============================| ===|=== ------------ ||MEMBER 1 * | AISC SECTIONS | | AX = 3.55 || * | ST W6X12 | | --Z AY = 1.25 ||DESIGN CODE * | | | AZ = 1.50 ||ANSI N690-94* =============================== ===|=== SY = 1.50 || * SZ = 7.33 || * |<---LENGTH (FT)= 9.35 --->| RY = 0.92 ||************* RZ = 2.50 || || 4.2 (KIP-FEET) ||PARAMETER | L1 STRESSES ||IN KIP INCH | L1 IN KIP INCH |

842— STAAD.Pro

ANSI/AISC N690-1994 Code

Page 853: International Codes v8i

|--------------- + L1 -------------|| KL/R-Y= 122.06 | L1 FA = 7.08 || KL/R-Z= 44.97 + L1 fa = 0.60 || UNL = 112.20 | FCZ = 19.86 || CB = 1.00 + L1 L1 FTZ = 21.60 || CMY = 0.85 | L1 FCY = 27.00 || CMZ = 0.85 + L1 FTY = 27.00 || FYLD = 36.00 |L0 L0 fbz = 6.84 || NSF = 1.00 +---+---+---+---+---+---+---+---+---+---| fby = 0.00 || DFF = 0.00 -0.2 Fey = 9.16 || dff= 0.00 ABSOLUTE MZ ENVELOPE Fez = 67.49 || (KL/R)max = 122.06 (WITH LOAD NO.) FV = 14.40 || fv = 0.54 || || MAX FORCE/ MOMENT SUMMARY (KIP-FEET) || ------------------------- || || AXIAL SHEAR-Y SHEAR-Z MOMENT-Y MOMENT-Z || || VALUE 2.1 1.6 0.0 0.0 4.2 || LOCATION 0.0 7.0 0.0 0.0 6.2 || LOADING 3 1 0 0 1 || ||**************************************************************************||* *||* DESIGN SUMMARY (KIP-FEET) *||* -------------- *||* *||* RESULT/ CRITICAL COND/ RATIO/ LOADING/ *|| FX MY MZ LOCATION || ====================================================== || PASS ANSI Q1.6-2 0.429 3 || 2.14 C 0.00 -4.18 6.23 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|

International Design Codes Manual — 843

Page 854: International Codes v8i

844— STAAD.Pro

Page 855: International Codes v8i

ANSI/AISC N690-1984 Code17B.1 General Comments

For code checking of steel members, STAAD compares the actual stresses with theallowable stresses as defined by the "ANSI/AISC N690-1984: Nuclear Facilities -Steel Safety-Related Structures for Design, Fabrication, and Erection."

A brief description of some of the major allowable stresses is described herein.

17B.2 Design Process

The following Checks are to be performed on a Steel Member as per this AISC N690– 1984 Code. When a design is performed, the output file the reports the maximumutilization from all of the checks.

17B.2.1. Slenderness

The maximum allowable slenderness ratio in Compression (K·L/r_min), as perclause Q1.8.4 of the code shall not exceed 200. And the maximum allowableslenderness ratio in Tension (L/r_min) shall not exceed 240 for main members and300 for bracing members and other secondary members.

This can be controlled by using the existing MAIN and TMAIN parametersrespectively.

The default value of MAIN is 200 and for TMAIN is 240.

17B.2.2. Check for Element Slenderness and Stress Reduction Fac-tors

The permissible Width-to-Thickness Ratio of “Un-stiffened Elements underCompression” is determined as per section Q1.9.1 and that of “Stiffened Elementsunder Compression” is determined as per section Q1.9.2 of the code.

The permissible Width–Thickness Ratio of web is determined as per sectionQ1.10.2.

17B.2.3. Tension

Allowable tensile stress on the Net section is calculated as 0.60·Fy, but not more

International Design Codes Manual — 845

Page 856: International Codes v8i

than 0.5·Fuon the Effective Net area, as per section Q1.5.1.1.

The Net Area (An) shall be determined in accordance with Q1.14, and the NSFparameter can be utilized for that.

The Effective Net Area (Ae) of axially loaded tension members, where the load istransmitted by bolts through some but not all of the cross-sectional elements ofthe member, shall be computed from the formula (ref. Q1.14),

Ae= C

t·An

Unless otherwise specified, the default value of the CT parameter is set as 0.75.

The value of CT parameter for other conditions is described at section Q1.14.

The provisions for Pin-connected and Threaded tensile member are notimplemented in STAAD.

17B.2.4. Compression

The allowable compressive stress for columns which meet the provisions of sectionQ1.9, except those fabricated from austenitic stainless steel shall be as required byQ1.5.1.3. The allowable compressive stress for columns fabricated from austeniticstainless steel shall be in accordance to section Q1.5.9.

A. Gross Sections of Columns, except those fabricated of austenitic stainlesssteel:

1. On gross section of axially loaded compression members, when (Kl/r)≤ C

c,

Fa= [1 - (Kl/r)2/(2·C

c2)]F

y/ {5/3 + [3(Kl/r)/(8·C

c)] -

[(Kl/r)3/(8·Cc3)]}

Where:

Cc= [(2·π2E)/F

y]1/2

2. When (Kl/r) > Cc,

Fa= 12·π2E/[23(kL/r)2]

B. Gross sections of columns fabricated from Austenitic Stainless steel:

846— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 857: International Codes v8i

1. When (Kl/r) ≤ 120,

Fa= F

y/2.15 - [(F

y/2.16 - 6)/120](kL/r)

2. When (Kl/r) > 120,

Fa= F

y[12 - (KL/r)/20]

If the provisions of the section Q1.9 are not satisfied,

A. For un-stiffened compression element, a reduction factor Qsis introduced.

Detailed values of Qs for different shapes are given in Section QC2.

B. For stiffened compression element, a reduced effective width beis

introduced.

1. For the flanges of square and rectangular sections of uniform thickness:

be= 253·t/√F

y{1 - (50.3/[(b/t)√F

y]} ≤ b

2. For other uniformly compressed elements:

be= 253·t/√F

y{1 - (44.3/[(b/t)√F

y]} ≤ b

Consequently, a reduction factor Qais introduced and is equal to the

effective area divided by the actual area. Combining both these factors,allowable stress for axially loaded compression members containingstiffened or unstiffened elements shall not exceed

Fa= Q

sQa[1 - (Kl/r)2/(2·C

c2)]F

y/ {5/3 + [3(Kl/r)/(8·C

c)] -

[(Kl/r)3/(8·Cc3)]}

Where:

C'c= [(2·π2E)/(Q

sQaFy)]1/2

17B.2.5.Bending Stress

Allowable bending stress for tension and compression for a structural member, asgiven in section Q1.5.1.4 is:

International Design Codes Manual — 847

Page 858: International Codes v8i

A. Along Major Axis:

1. Tension and compression on extreme fibers of compact hot rolled orbuilt-up members symmetrical about and loaded in the plane of theirminor axes and meeting the requirements of Subsection Q1.5.1.4.1.1to 7, shall result in a maximum bending stress:

Fb= 0.66·F

y

If meeting the requirements of this member of:

a. Width-thickness ratio of unstiffened projecting elements of thecompression flange shall not exceed 65/√F

y.

b. Width-thickness ratio of stiffened elements of the compressionflange shall not exceed 190/√F

y.

c. The depth-thickness ratio of the web shall not exceed

d/t = (640/√Fy)[1 – 3.74(f

a/Fy)] when f

a/Fy≤0.16

d/t = 257/√Fywhen f

a/Fy> 0.16

d. The laterally unsupported length of the compression flange ofmembers other than box-shaped members shall not exceed thevalue of 76b

f/√F

ynor 20000/(d/A

f)Fy.

2. For noncompact and slender elements, section Q1.5.1.4.2 is followed.

3. For box-type flexural members, maximum bending stress is:

Fb= 0.60·F

y

B. Along Minor Axis:

1. For doubly symmetrical members (I shaped) meeting the requirementsof section Q1.5.1.4.1, maximum tensile and compressive bendingstress shall not exceed the following value as per section Q1.5.1.4.3:

Fb= 0.75·F

y

2. For doubly symmetrical members (I shaped) meeting the requirementsof section Q1.5.1.4.1, except where b

f/2t

f> 65/√F

ybut is less than

95/√Fy, maximum tensile and compressive bending stress shall not

exceed:

Fb= F

y[0.79 – 0.002(b

f/2t

f)√F

y]

848— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 859: International Codes v8i

17B.2.6. Combined Interaction Check

Members subjected to both axial compression and bending stresses areproportioned to satisfy equation Q1.6-1a:

SFC·fa/Fa+ SMY·C

myfby/[(1 - f

a/F'

ey)Fby] +  SMZ·C

mzfbz/[(1 - f

a/F'

ez)Fbz] ≤ 1.0

and Q1.6-1b

SFC·fa/(0.6·F

y) + SMY·f

by/Fby+  SMZ·f

bz/Fbz≤ 1.0

when, fa/Fa> 0.15, as per section Q1.6.1 of the code.

Otherwise, equation Q1.6-2 must be satisfied:

SFC·fa/Fa+ SMY·f

by/Fby+ SMZ·f

bz/Fbz≤ 1.0

It should be noted that during code checking or member selection, if fa/Faexceeds

unity, the program does not compute the second and third part of the formula,because this would result in a misleadingly liberal ratio. The value of the coefficientCm is taken as 0.85 for side-sway and [0.6 - 0.4·(M1/M2)], but not less than 0.4 forno side-sway.

Members subjected to both axial tension and bending stress are proportioned tosatisfy equation Q 1.6-1b:

SFT·fa/(0.6·F

y) + SMY·f

by/Fby+ SMZ·f

bz/Fbz≤ 1.0

Where SFC, SFT, SMZ, and SMY are stress limit coefficient parameters used tocontrol the components of the interaction equations. Refer to Table 17B.1 fordetails.

17B.2.7. Shear Stress

Allowable shear stress on the gross section [ref. section Q1.10.5.2] is calculated as

Fv= (F

y/2.89)C

v≤ 0.4·F

y

Where:

Cv= (45,000·k)/[F

y(h/t)2], when h/t ≤ 0.8

Cv= [190/(h/t)]√(k/F

y), when h/t > 0.8

k = 4.00 + [5.34/(a/h)2], when a/h ≤ 1.0

International Design Codes Manual — 849

Page 860: International Codes v8i

k = 5.34 + [4.00/(a/h)2], when a/h > 1.0

For actual shear on the web, the gross section is taken as the product of the totaldepth and the web thickness. For shear on the flanges, the gross section is takenas the total flange areas.

17B.4 Member Property Specification

For  specification of member properties, the specified steel section available inSteel Section Library of STAAD may be used, namely: I-shaped section, Channel,Tee, HSS Tube, HSS Pipe, Angle, Double Angle, and Double Channel sections.

Member properties may also be specified using the User Table facility except forthe General and Prismatic member.

For more information on these facilities, refer to Section 1.7 the STAAD TechnicalReference Manual.

17B.4 Design Parameters

The program contains a large number of parameter names which are required toperform design and code checks. These parameter names, with their defaultvalues, are listed in the following table.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements for an analysis, some or all of these parameter values may have to bechanged to exactly model the physical structure

ParameterName

DefaultValue

Description

CODE - Must be specified as AISC N6901984 to use the ANSI/AISC N690-1984 code for checking purposes.

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

CAN 0 Used for Deflection Check only.

Table 17B.1 - Design Parameters for ANSI/AISC N690-1984

850— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 861: International Codes v8i

ParameterName

DefaultValue

Description

0 = Deflection checkbased on the principlethat maximum deflectionoccurs within the spanbetween DJ1 and DJ2.

1 = Deflection checkbased on the principlethat maximum deflectionis of the cantilever type

CB 1.0 Bending coefficient dependent uponmoment gradient

0.0 = CB is calculated itself

Any other user-defined value isaccepted.

CMY

CMZ

0.85 forsideswayand

calculatedfor nosidesway

Cm value in local y & z axes

CT 0.75 Reduction Coefficient in computingnet effective net area of an axiallyloaded tension member.

DFF None(Mandatory

fordeflectioncheck)

"Deflection Length" / Maximumallowable local deflection

DJ1 Start Jointof member

Joint No. denoting starting point forcalculation of "Deflection Length"

DJ2 End Jointof member

Joint No. denoting end point forcalculation of "Deflection Length"

International Design Codes Manual — 851

Page 862: International Codes v8i

ParameterName

DefaultValue

Description

DMAX 45 inch Maximum allowable depth

DMIN 0.0 inch Minimum allowable depth

FU 60 KSI Ultimate tensile strength of steel incurrent units.

FYLD 36 KSI Yield strength of steel in currentunits.

KY 1.0 Effective Length Factor for Com-pression in local y-axis. Usually, thisis minor axis.

KZ 1.0 Effective Length Factor for Com-pression in local z-axis. Usually, thisis major axis.

LY MemberLength

Length to calculate slenderness ratiofor buckling about local Y axis.

LZ MemberLength

Same as above except in z-axis(major).

MAIN 0.0 Design for slenderness.

0. Check for slenderness

1. Suppress slenderness check

NSF 1.0 Net section Factor for tensionmembers

PROFILE None Used to search for the lightest sectionfor the profile(s) specified formember selection. See Section 5.48.1of the Technical Reference Manual fordetails. 

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

SFC 1.0 Stress limit coefficient for com-

852— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 863: International Codes v8i

ParameterName

DefaultValue

Description

pression (SLC) as found in Table Q1.5.7.1.

SFT 1.0 Stress limit coefficient for tension(SLC) as found in Table Q 1.5.7.1.

SMY 1.0 Stress limit coefficient for minor axisbending (SLC) as found in Table Q1.5.7.1.

SMZ 1.0 Stress limit coefficient for major axisbending (SLC) as found in Table Q1.5.7.1.

STIFF Memberlength ordepth

whicheveris greater

Spacing of stiffeners for plate girderdesign

STYPE 0.0 0.0 = Normal Steel

1.0 = Austenitic Stainless Steel

TMAIN 240 formainmember

300 for“Truss”member

Slenderness limit under tension

TRACK 0.0 Controls the levels of detail to whichresults are reported.

0 = Minimum detail

1 = Intermediate detail level

2 = Maximum detail

UNB MemberLength

Unsupported length of the bottom*flange for calculating allowable

International Design Codes Manual — 853

Page 864: International Codes v8i

ParameterName

DefaultValue

Description

bending compressive stress. Will beused only if flexural compression onthe bottom flange.

UNT MemberLength

Unsupported length of the top*flange for calculating allowablebending compressive stress. Will beused only if flexural compression onthe top flange.

Notes

1. All values are entered in the current units

2. parameters DMAX and DMIN are only used with the MEMBER SELECTION com-mand

17B.5 Code Checking and Member Selection

Both code checking and member selection options are available with the AISCN690 1984 code.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

17B.6 Examples

These example problems are included for the verification of design results.

17B.6.1 Example 1 - Pipe Section

This example is included as C:\SPROV8I\STAAD\EXAMP\NUCLEAR CODESAMPLES\N690_1984_PIPE_SECTION.STD

854— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 865: International Codes v8i

Problem

A 10 ft long simply supported beam subject to axial (+/- 10 kip) and bending loads(3 kip/ft) in both the local y and z axis. The beam is a 5" diameter, Schedule 40 Pipesection made from Grade 36 steel.

Solution

Section Properties:

Ax= 4.30 in.2

Iy= I

z= 15.20 in.4

r = (15.20/4.30)1/2 = 1.88 in.

O.D. = 5.56 in., t = 0.26 in.

Sx= S

y= 15.20 in.4·2/5.56 in. = 5.468 in.3

Load Case 1: Tension-only

Allowable Tensile Stress:

Ft= min(0.6·F

y, 0.5·F

u) = 0.6(36 ksi) = 21.60 ksi

Actual Tensile Stress:

ft= P/A

e

Where:

Ae= C

t·An= 0.75(4.30 in.2) = 3.23 in.2

ft= 10 kip/ 3.23 in.2 = 3.10 ksi

Stress Ratio = 3.10 ksi/21.60 ksi = 0.144 < 1.0, OK.

Load Case 2: Compression-only

Allowable Compressive Stress:

Maximum Slenderness Ratio, (Kl/r)max

= 1.0(10 ft)(12 ft/in.)/1.88in. =63.83 < 200, OK.

Yield Stress of Steel, Fy= 36 ksi

International Design Codes Manual — 855

Page 866: International Codes v8i

Cc= [(2π2E)/F

y]1/2 = 127.68

(Kl/r)max

< Cc

Fa= F

y[1.0 - (Kl/r)2/(2·C

c2]/[5/3 + 3(Kl/r)/(8·C

c) - (Kl/r)3/(2·C

c3)] =

36.0 ksi{1.0 - (63.83)2/[2(127.68)2]/{5/3 + 3(63.83)/[8(127.68)] -(63.83)3/[8(127.68)3]} = 36.0 ksi (0.875/1.835) = 17.06 ksi

Actual Compressive Stress:

fa= 10 kip/4.30 in.2 = 2.33 ksi

Stress Ratio = 2.33 ksi/17.06 ksi = 0.136 < 1.0, OK.

Load Case 3: Tension + Bending

Allowable Bending Stress:

Fby= F

bz= 0.66·F

y= 0.66(36 ksi) = 23.76 ksi

Actual Bending Stress (include member selfweight in Y dir.):

My= 0.315 kip/ft (10 ft)2/8 (12 in./ft) = 47.2 in·kip

Mz= 0.3 kip/ft (10 ft)2/8 (12 in./ft) = 45.0 in·kip

fby= 47.2 in·kip/5.468 in.3 = 8.63 ksi

fbz= 45.0 in·kip/5.468 in.3 = 8.23 ksi

Stress Ratio = 8.63 ksi/ 23.76 ksi = 0.363 < 1.0

Stress Ratio = 8.23 ksi/ 23.76 ksi = 0.346 < 1.0

Combined Stress Check:

fa/(0.6·F

y) + f

by/Fby+  f

bz/Fbz= 3.10 ksi/[0.6(36 ksi)] + 0.363 + 0.346 =

0.853

Load Case 4: Compression + Bending

Combined Stress Check:

fa/Fa= 0.136 < 0.15

fa/Fa+ f

by/Fby+  f

bz/Fbz= 0.136 + 0.363 + 0.346 = 0.845 < 1.0, OK

856— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 867: International Codes v8i

Comparison

Condition Reference STAAD.Pro Difference

Tension 0.144

(0.107, CT= 1.0)

0.108

Compression 0.136 0.136 None

Tension+ Bending

0.853

(0.817, CT= 1.0)

0.815 2.51%

Compression+ Bending

0.845 0.844 Negligible

Table 17B.2 - ANSI/AISC N690-1984 Code VerificationProblem 1

Input File

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 09-DEC-09

END JOB INFORMATION

INPUT WIDTH 79

UNIT FEET KIP

JOINT COORDINATES

1 0 0 0; 2 10 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 4.176E+006

International Design Codes Manual — 857

Page 868: International Codes v8i

POISSON 0.3

DENSITY 0.489024

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

UNIT INCHES KIP

MEMBER PROPERTYAMERICAN

1 TABLE ST PIPS50

UNIT FEET KIP

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 PINNED

2 FIXED BUT FX

LOAD 1 TENSION ONLY

JOINT LOAD

2 FX 10

LOAD 2 COMPRESSION ONLY

JOINT LOAD

2 FX -10

LOAD 3 TENSION+BENDING

SELFWEIGHT Y -1

MEMBER LOAD

1 UNIGY -0.3

JOINT LOAD

2 FX 10

MEMBER LOAD

1 UNIGZ 0.3

LOAD 4 COMPRESSION+BENDING

SELFWEIGHT Y -1

858— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 869: International Codes v8i

MEMBER LOAD

1 UNIGY -0.3

JOINT LOAD

2 FX -10

MEMBER LOAD

1 UNIGZ 0.3

PERFORMANALYSIS PRINT LOAD DATA

PRINT MEMBER PROPERTIES ALL

UNIT INCHES KIP

LOAD LIST 1

PARAMETER 1

CODE AISC N690 1984

CB 1 ALL

CMY0 ALL

CMZ 0 ALL

* 36 & 58

FYLD 36 ALL

FU 58 ALL

KY 1 ALL

KZ 1 ALL

MAIN 200 ALL

NSF 1 ALL

RATIO 1 ALL

TMAIN 300 ALL

TRACK 2 ALL

UNB 30 ALL

UNT 30 ALL

CT 0.75 ALL

CHECK CODE ALL

International Design Codes Manual — 859

Page 870: International Codes v8i

** FOLLOWING TOCHECK IF THE NET AREA IS USED INCALCULATING TENSILE STRESS

PARAMETER 11

CODE AISC N690 1984

FU 40 ALL

CHECK CODE ALL

LOAD LIST 2

PARAMETER 2

CODE AISC N690 1984

CB 1 ALL

CMY0 ALL

CMZ 0 ALL

* 36 & 58

FYLD 36 ALL

FU 58 ALL

KY 1 ALL

KZ 1 ALL

MAIN 200 ALL

NSF 1 ALL

RATIO 1 ALL

TMAIN 300 ALL

TRACK 2 ALL

UNB 30 ALL

UNT 30 ALL

CT 0.75 ALL

CHECK CODE ALL

LOAD LIST 3

PARAMETER 3

CODE AISC N690 1984

CB 1 ALL

860— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 871: International Codes v8i

CMY0 ALL

CMZ 0 ALL

* 36 & 58

FYLD 36 ALL

FU 58 ALL

KY 1 ALL

KZ 1 ALL

MAIN 200 ALL

NSF 1 ALL

RATIO 1 ALL

TMAIN 300 ALL

TRACK 2 ALL

UNB 30 ALL

UNT 30 ALL

CT 0.75 ALL

CHECK CODE ALL

LOAD LIST 4

PARAMETER 4

CODE AISC N690 1984

CB 1 ALL

CMY0 ALL

CMZ 0 ALL

* 36 & 58

FYLD 36 ALL

FU 58 ALL

KY 1 ALL

KZ 1 ALL

MAIN 200 ALL

NSF 1 ALL

RATIO 1 ALL

International Design Codes Manual — 861

Page 872: International Codes v8i

TMAIN 300 ALL

TRACK 2 ALL

UNB 30 ALL

UNT 30 ALL

CT 0.75 ALL

CHECK CODE ALL

LOAD LIST ALL

PARAMETER 5

CODE AISC N690 1984

CB 1 ALL

CMY0 ALL

CMZ 0 ALL

* 36 & 58

FYLD 36 ALL

FU 58 ALL

KY 1 ALL

KZ 1 ALL

MAIN 200 ALL

NSF 1 ALL

RATIO 1 ALL

TMAIN 300 ALL

TRACK 2 ALL

UNB 30 ALL

UNT 30 ALL

CT 0.75 ALL

CHECK CODE ALL

FINISH

Output

The TRACK 2 output for the final parameter set is shown here:

862— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 873: International Codes v8i

STAAD.PRO CODE CHECKING - ( AISC N690 1984)v1.0

********************************************

ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 ST PIPS50 (AISC SECTIONS)PASS Q1.6-Eqn 2 0.844 4

10.00 C 44.84 47.02 120.00|-----------------------------------------------------------------------------|| SLENDERNESS CHECK: ACTUAL RATIO: 63.83 ALLOWABLE RATIO: 200.00

|| ALLOWABLE STRESSES: (UNIT - KIP INCH)

|| AXIAL: 1.71E+01 FCZ: 2.38E+01 FCY: 2.38E+01 FTZ: 2.38E+01 FTY:2.38E+01 || SHEAR: 1.44E+01

|| ACTUAL STRESSES: (UNIT - KIP INCH)

|| AXIAL: 2.33E+00 FBZ: 8.60E+00 FBY: 8.20E+00 SHEAR: 9.12E-01

||-----------------------------------------------------------------------------|| SECTION PROPERTIES: (UNIT - INCH)

|| AXX: 4.30 AYY: 2.27 AZZ: 2.27 RZZ: 1.88 RYY: 1.88

|| SZZ: 5.46 SYY: 5.46

||-----------------------------------------------------------------------------|| PARAMETER: (UNIT - KIP INCH)

|| KL/R-Z: 63.83 KL/R-Y: 63.83 UNL: 30.0 CMZ: 0.60 CMY:0.60 || CB: 1.00 FYLD: 36.00 FU: 58.00 NET SECTION FACTOR: 1.00

|| CT: 0.75 STEEL TYPE: 0.0

||-----------------------------------------------------------------------------|| CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS KIP -INCH)

|| CLAUSE RATIO LOAD FX VY VZ MZMY || TENSION 0.108 1 1.00E+01 - - -- |

International Design Codes Manual — 863

Page 874: International Codes v8i

| COMPRESSION 0.136 2 1.00E+01 - - -- |

| COMP&BEND 0.844 4 1.00E+01 - - 4.70E+014.48E+01 || TEN&BEND 0.815 3 1.00E+01 - - 4.70E+014.48E+01 || SHEAR-Y 0.063 3 - 1.96E+00 - -

- || SHEAR-Z 0.060 3 - - 1.87E+00 -

- ||-----------------------------------------------------------------------------|

17B.6.2 Example 2 - W-Section

This example is included as C:\SPROV8I\STAAD\EXAMP\NUCLEAR CODESAMPLES\N690_1984_W-SECTION.STD

Problem

A 12 ft long simply supported beam subject to uniform load (3 kip/ft). The beam isa W6x12 section made from Grade 36 steel.

Solution

Section Properties:

A = 3.55 in.2

d = 6.03 in.

tw= 0.230 in.

Sz= 7.31 in.3

Allowable Bending Stress:

Fbz= 0.66·F

y= 0.66(36 ksi) = 23.76 ksi

Actual Bending Stress (include member selfweight in Y dir.):

Mz= 0.312 kip/ft (12 ft)2/8 (12 in./ft) = 67.4 in·kip

fbz= 67.4 in·kip/7.31 in.3 = 9.22 ksi

Stress Ratio = 9.22 ksi/ 23.76 ksi = 0.388 < 1.0, OK

Allowable Shear Stress:

864— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 875: International Codes v8i

Fv= 0.4·F

y= 0.4(36 ksi) = 14.40 ksi

Actual Shear Stress:

Vz= 0.5(12 ft)(0.312 kip/ft) = 1.872 kip

fvz= 1.872 kip/(6.03 in. x 0.230 in.) = 1.35 ksi

Stress Ratio = 1.35 ksi/ 14.40 ksi = 0.094 < 1.0, OK.

Comparison

Condition Reference STAAD.Pro Difference

Bending 0.388 0.387 Negligible

Shear 0.094 0.094 None

Table 17B.3 - ANSI/AISC N690-1984 Code Ver-ification Problem 3

Input File

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 09-DEC-09

END JOB INFORMATION

INPUT WIDTH 79

UNIT FEET KIP

JOINT COORDINATES

1 0 0 0; 2 12 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 4.176E+006

POISSON 0.3

International Design Codes Manual — 865

Page 876: International Codes v8i

DENSITY 0.489024

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

1 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 2 PINNED

LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

SELFWEIGHT Y -1 ALL

MEMBER LOAD

1 UNIGY -0.3

PERFORMANALYSIS PRINT LOAD DATA

PRINT MEMBER PROPERTIES ALL

*UNIT KIP INCH

PARAMETER 1

CODE AISC N690 1984

CB 1 ALL

CMY0 ALL

CMZ 0 ALL

* 36 & 58

FYLD 36 ALL

FU 58 ALL

KY 1 ALL

KZ 1 ALL

MAIN 200 ALL

NSF 1 ALL

RATIO 1 ALL

866— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 877: International Codes v8i

TMAIN 300 ALL

TRACK 2 ALL

UNB 3 ALL

UNT 3 ALL

UNIT KIP INCH

CHECK CODE ALL

FINISH

Output

The TRACK 2 output for the final parameter set is shown here:

STAAD.PRO CODE CHECKING - ( AISC N690 1984)v1.0

********************************************

ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 ST W6X12 (AISC SECTIONS)PASS Q1.6-Eqn 2 0.387 1

0.00 T 0.00 -67.40 72.00|-----------------------------------------------------------------------------|| SLENDERNESS CHECK: ACTUAL RATIO: 156.64 ALLOWABLE RATIO: 300.00

|| ALLOWABLE STRESSES: (UNIT - KIP INCH)

|| AXIAL: 6.09E+00 FCZ: 2.38E+01 FCY: 2.70E+01 FTZ: 2.38E+01 FTY:2.70E+01 || SHEAR: 1.44E+01

|| ACTUAL STRESSES: (UNIT - KIP INCH)

|| AXIAL: 0.00E+00 FBZ: 9.20E+00 FBY: 0.00E+00 SHEAR: 0.00E+00

||-----------------------------------------------------------------------------|| SECTION PROPERTIES: (UNIT - INCH)

|| AXX: 3.55 AYY: 1.39 AZZ: 1.49 RZZ: 2.50 RYY: 0.92

|

International Design Codes Manual — 867

Page 878: International Codes v8i

| SZZ: 7.33 SYY: 1.50|

|-----------------------------------------------------------------------------|| PARAMETER: (UNIT - KIP INCH)

|| KL/R-Z: 57.71 KL/R-Y:156.64 UNL: 36.0 CMZ: 0.60 CMY:0.60 || CB: 1.00 FYLD: 36.00 FU: 58.00 NET SECTION FACTOR: 1.00

|| CT: 0.75 STEEL TYPE: 0.0

||-----------------------------------------------------------------------------|| CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS KIP -INCH)

|| CLAUSE RATIO LOAD FX VY VZ MZMY |

| TENSION 0.000 1 0.00E+00 - - -- |

| COMPRESSION 0.000 1 0.00E+00 - - -- |

| COMP&BEND 0.387 1 0.00E+00 - - 6.74E+010.00E+00 || TEN&BEND 0.000 1 0.00E+00 - - 6.74E+010.00E+00 || SHEAR-Y 0.094 1 - 1.87E+00 - -

- || SHEAR-Z 0.000 1 - - 0.00E+00 -

- ||-----------------------------------------------------------------------------|

868— STAAD.Pro

ANSI/AISC N690-1984 Code

Page 879: International Codes v8i

Section 18

American Society ofMechanical Engineers –Nuclear Facility (ASMENF) Codes

International Design Codes Manual — 869

Page 880: International Codes v8i

870— STAAD.Pro

Page 881: International Codes v8i

ASME NF 3000 - 1974 & 1977 Codes18A.1 General Comments

For steel design, STAAD compares the actual stresses with the allowable stresses asdefined by the American Society of Mechanical Engineers – Nuclear Facility (ASMENF) Code. The ASME NF-3000 1974 Code is used as the basis of this design.

From design point of view, there are no major differences between NF-3000 1974and NF-3000 1977 version of codes.

A brief description of some of the major allowable stresses is described herein.

18A.2 Design Process

The design process follows the following design checks

1. Slenderness

2. Tension

3. Compression

4. Bending Stress

5. Combined Interaction Check

6. Shear Stress

Each one of the checks are described in the following sections.

When a design is performed, the output file the reports the maximum utilizationfrom all of the checks.

18A.2.1   Slenderness 

As per clause XVII-2223 of NF-3000 1974, the slenderness ratio KL/r ofcompression members shall not exceed 200, and the slenderness ratio L/r oftension members, preferably should not exceed 240 for main members and 300 forlateral bracing members and other secondary members. The default limit for TRUSSmembers in Tension is set at 300.

International Design Codes Manual — 871

Page 882: International Codes v8i

18A.2.2   Tension

Allowable tensile stress on the Net section is calculated as (0.60*Fy), but not more

than (0.5*Fu) on the Net area.

The Net Area (An) shall be determined in accordance with the clause XVII-2283 ofNF-3000 1974, and the NSF parameter can be utilized for that. 

The provisions for Pin-connected and Threaded tensile member are notimplemented in STAAD.

18A.2.3 Compression

The allowable compressive stress for columns shall be as required by clause XVII-2213 of NF-3000 1974.

a. Gross Sections of Columns:

1. On gross section of axially loaded compression members, when (Kl/r)< C

c,

Where:

2. When (Kl/r) > Cc,

3. When (Kl/r) > 120,

b. Member elements other than columns:

872— STAAD.Pro

ASME NF 3000 - 1974 & 1977 Codes

Page 883: International Codes v8i

1. For Plate Girder Stiffeners, Fa= 0.60·F

y2. For webs of rolled shapes, F

a= 0.75·F

y

The above clauses are applicable only when the width-thickness ratio of theelement satisfies all the sub-sections of clause XVII-2224 of NF-3000 1974.

If the above-mentioned clauses are not satisfied,

a. For un-stiffened compression element, a reduction factor, Qs, is introduced.

Detailed values of Qsfor different shapes are given in the clause XVII-2225.2

of NF-3000 1974.

b. For stiffened compression element, a reduced effective width, be, is

introduced.

1. For the flanges of square and rectangular sections of uniform thickness:

2. For other uniformly compressed elements:

Consequently, a reduction factor, Qa, equal to the effective area divided by

the actual area is introduced.

Combining both these factors, allowable stress for axially loaded compressionmembers containing stiffened or un-stiffened elements shall not exceed

Where:

International Design Codes Manual — 873

Page 884: International Codes v8i

18A.2.4   Bending Stress

Allowable bending stress for tension and compression for a structural member, asgiven in XVII-2214 of NF-3000 1974 is:

a. Along Major Axis:

a. For Compact Sections, tension and compression on extreme fibers ofcompact hot rolled or built-up members symmetrical about and loaded in theplane of their minor axes and meeting the requirements of Subsection NFshall result in a maximum bending stress:

Fb= 0.66*F

y

If meeting the requirements of this member of:

a. Width-thickness ratio of un-stiffened projecting elements of the compressionflange shall not exceed 52.2/√F

y.

b. Width-thickness ratio of stiffened elements of the compression flange shallnot exceed 190/√F

y.

c. The depth-thickness ratio of the web shall not exceed

d/t = (412/√Fy)[1 – 2.33(F

a/Fy)]                  

except that it need not be less than 257/√Fy.                                     

d. The laterally unsupported length of the compression flange of membersother than box-shaped members shall not exceed the value of 76b

f/√F

ynor

20000/(d/Af)Fy.

b. For noncompact and slender elements, clause XVII-2214.2 and XVII-2214.5of NF-3000 1974 are followed respectively.

c. For box-type flexural members, maximum bending stress is:

   Fb= 0.60*F

y

b. Along Minor Axis:

For doubly symmetrical members (I shaped) meeting the requirements of XVII-2214.1(a) and (b) of NF-3000 1974, maximum tensile and compressive bendingstress shall not exceed:

Fb= 0.75*F

y

874— STAAD.Pro

ASME NF 3000 - 1974 & 1977 Codes

Page 885: International Codes v8i

18A.2.5   Combined Interaction Check

Members subjected to both axial compression and bending stresses areproportioned to satisfy

and

when fa/Fa> 0.15,

otherwise

It should be noted that during code checking or member selection, if fa/Faexceeds

unity, the program does not compute the second and third part of the formula,because this would result in a misleadingly liberal ratio. The value of the coefficientCm is taken as 0.85 for side-sway and 0.6 - 0.4·(M1/M2), but not less than 0.4 forno side-sway.

Members subjected to both axial tension and bending stress are proportioned tosatisfy

18A.2.6   Shear Stress 

Allowable shear stress on the gross section [ref. XVII-2263.2 of NF-3000 1974] iscalculated as

Where:

International Design Codes Manual — 875

Page 886: International Codes v8i

, when Cv< 0.8

, when Cv> 0.8

, when a/h < 1.0

, when a/h > 1.0

For actual shear on the web, the gross section is taken as the product of the totaldepth and the web thickness. For shear on the flanges, the gross section is takenas the total flange areas.

18A.3 Member Property Specification

For  specification of member properties, the specified steel section available inSteel Section Library of STAAD may be used namely – I-shaped section, Channel,Tee, HSS Tube, HSS Pipe, Angle, Double Angle, Double Channel section.

Member properties may also be specified using the User Table facility except forthe General and Prismatic member.

For more information on these facilities, refer to Section 1.7 the STAAD TechnicalReference Manual.

18A.4 Design Parameters

The program contains a large number of parameter names which are required toperform design and code checks. These parameter names, with their defaultvalues, are listed in the following table.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements for an analysis, some or all of these parameter values may have to bechanged to exactly model the physical structure. For example, by default the KZvalue (k value in local z-axis) of a member is set to 1.0, while in the real structure itmay be 1.5. In that case, the KZ value in the program can be changed to 1.5, asshown in the input instruction (Section 5). Similarly, the TRACK value of a memberis set to 0.0, which means no allowable stresses of the member will be printed. Ifthe allowable stresses are to be printed, the TRACK value must be set to 1.0.

876— STAAD.Pro

ASME NF 3000 - 1974 & 1977 Codes

Page 887: International Codes v8i

ParameterName

DefaultValue

Description

CODE - Must be specified as CODE NF30001974 or CODE NF3000 1977

Design Code to follow. See section5.48.1 of the Technical ReferenceManual.

CAN 0 Used for Deflection Check only.

0 = Deflection check based on theprinciple that maximum deflectionoccurs within the span betweenDJ1 and DJ2.

1 = Deflection check based on theprinciple that maximum deflectionis of the cantilever type

CB 1.0 Bending coefficient dependentupon moment gradient

0.0 = CB is calculated itself

Any other user-defined value isaccepted.

CMY

CMZ

0.85 forsideswayand

calculatedfor nosidesway

Cm value in local y & z axes

DFF None(Mandatory

fordeflectioncheck)

"Deflection Length" / Maximumallowable local deflection

DJ1 Start Jointof member

Joint No. denoting starting point

Table 18A.1 - ASME NF 3000 Design Parameters

International Design Codes Manual — 877

Page 888: International Codes v8i

ParameterName

DefaultValue

Description

for calculation of "DeflectionLength"

DJ2 End Joint ofmember

Joint No. denoting end point forcalculation of "Deflection Length"

DMAX 45 inch Maximum allowable depth. Usedonly with the MEMBER SELECTIONcommand.

DMIN 0.0 inch Minimum allowable depth. Usedonly with the MEMBER SELECTIONcommand.

FYLD 36 KSI Yield strength of steel in currentunits.

FU 60 KSI Ultimate tensile strength of steel incurrent units.

KY 1.0 K value in local y-axis. Usually, thisis minor axis.

KZ 1.0 K value in local z-axis. Usually, thisis major axis.

LY MemberLength

Length to calculate slendernessratio for buckling about local Y axis.

LZ MemberLength

Same as above except in z-axis(major).

MAIN 0.0 0.0 = check for slenderness

1.0 = suppress slenderness check

NSF 1.0 Net Section Factor for tensionmember.

PROFILE None Used in member selection. SeeSection 5.48.1 of the TechnicalReference Manual for details. 

878— STAAD.Pro

ASME NF 3000 - 1974 & 1977 Codes

Page 889: International Codes v8i

ParameterName

DefaultValue

Description

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

STIFF Memberlength ordepth

whichever isgreater

Spacing of stiffeners for plategirder design

TMAIN 240 formainmember

300 for“Truss”member

Slenderness limit under tension

TRACK 0.0 Controls the levels of detail towhich results are reported.

0. Minimum detail

1. Intermediate detail level

2. Maximum detail

UNB MemberLength

Unsupported length of the bottom*flange for calculating allowablebending compressive stress. Will beused only if flexural compressionon the bottom flange.

UNT MemberLength

Unsupported length of the top*flange for calculating allowablebending compressive stress. Will beused only if flexural compressionon the top flange.

18A.5 Code Checking and Member Selection

Both code checking and member selection options are available with the ASME NF-3000 1974 and ASME NF-3000 1977 codes.

International Design Codes Manual — 879

Page 890: International Codes v8i

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

18A.6 Example  

A cantilever beam of length 30 inch is loaded at its free end with 5 kip compressiveload and 5 kip lateral load. The beam is assigned with W24X104 steel member andis designed in accordance with ASME NF3000 1974.

The corresponding input of STAAD input editor file is shown as below:

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 18-JUN-08

END JOB INFORMATION

UNIT INCHES KIP

JOINT COORDINATES

1 0 0 0; 2 30 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 29000

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

1 TABLE ST W24X104

880— STAAD.Pro

ASME NF 3000 - 1974 & 1977 Codes

Page 891: International Codes v8i

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

JOINT LOAD

2 FX -5 FY -5

PERFORMANALYSIS

PRINT SUPPORT REACTION

PRINT JOINT DISPLACEMENTS

PRINT MEMBER FORCES

PARAMETER 1

CODENF3000 1974

FYLD 36 ALL

FU 58 ALL

KY 0.9 ALL

KZ 0.9 ALL

NSF 0.85 ALL

CB 0 ALL

TRACK 2 ALL

CHECK CODE ALL

FINISH

The corresponding TRACK 2 output is as follows:STAAD.PRO CODE CHECKING - ( ASME NF3000-74) v1.0********************************************

ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/FX MY MZ LOCATION

=======================================================================

1 ST W24X104 (AISC SECTIONS)PASS NF-74-EQN-21 0.032 1

5.00 C 0.00 150.00 0.00|-----------------------------------------------------------------------------|| SLENDERNESS CHECK: ACTUAL RATIO: 9.28 ALLOWABLE RATIO: 200.00 |

International Design Codes Manual — 881

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| ALLOWABLE STRESSES: (UNIT - KIP INCH) || AXIAL: 2.07E+01 FCZ: 2.38E+01 FCY: 2.70E+01 FTZ: 2.38E+01 FTY: 2.70E+01 || SHEAR: 1.44E+01 || ACTUAL STRESSES: (UNIT - KIP INCH) || AXIAL: 1.63E-01 FBZ: 5.82E-01 FBY: 0.00E+00 SHEAR: 4.16E-01 ||-----------------------------------------------------------------------------|| SECTION PROPERTIES: (UNIT - INCH) || AXX: 30.60 AYY: 12.03 AZZ: 12.75 RZZ: 10.07 RYY: 2.91 || SZZ: 257.69 SYY: 40.63 ||-----------------------------------------------------------------------------|| PARAMETER: (UNIT - KIP INCH) || KL/R-Z: 2.68 KL/R-Y: 9.28 UNL: 30.0 CMZ: 1.00 CMY: 1.00 || CB: 1.75 FYLD: 36.00 FU: 58.00 NET SECTION FACTOR: 0.85 || ||-----------------------------------------------------------------------------|| CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS KIP -INCH) || CLAUSE RATIO LOAD FX VY VZ MZ MY || TENSION 0.009 1 5.00E+00 - - - - || COMPRESSION 0.008 1 5.00E+00 - - - - || COMP&BEND 0.032 1 5.00E+00 - - 1.50E+02 0.00E+00 || TEN&BEND 0.000 1 5.00E+00 - - 1.50E+02 0.00E+00 || SHEAR-Y 0.029 1 - 5.00E+00 - - - || SHEAR-Z 0.000 1 - - 0.00E+00 - - ||-----------------------------------------------------------------------------|

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ASME NF 3000 - 1989 Code18B.1 General Comments

For steel design, STAAD compares the actual stresses with the allowable stresses asdefined by the American Society of Mechanical Engineers – Nuclear Facility (ASMENF) Code. The ASME NF-3000 1989 Code is used as the basis of this design.

A brief description of some of the major allowable stresses is described herein.

18B.2 Design Process

The design process follows the following design checks.

1. Slenderness

2. Tension

3. Compression

4. Bending Stress

5. Combined Interaction Check

6. Shear Stress

Each one of the checks are described in the following sections.

When a design is performed, the output file the reports the maximum utilizationfrom all of the checks.

18B.2.1 Slenderness

As per NF-3322.2(c), the slenderness ratio KL/r of compression members shall notexceed 200, and the slenderness ratio L/r of tension members, preferably shouldnot exceed 240 for main members and 300 for lateral bracing members and othersecondary members. The default limit for TRUSS members in Tension is set at 300.

18B.2.2 Tension  

Allowable tensile stress on the Net section is calculated as (0.60*Fy), but not more

than (0.5*Fu) on the Effective Net area.

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The Net Area (An) shall be determined in accordance with NF-3322.8(c)(1) - (a),

(b) and (c), and the NSF parameter can be utilized for that.

The Effective Net Area (Ae) of axially loaded tension members, where the load is

transmitted by bolts through some but not all of the cross-sectional elements ofthe member, shall be computed from the formula (ref. NF-3322.8(c)(1)(d)),

Ae= C

t* An

Unless otherwise specified, the default value of the CT parameter is set as 0.75.

The value of CT parameter for other conditions is described at section NF-3322.8(c)(1)(d)(1), (2) and (3).

The provisions for Pin-connected and Threaded tensile member are notimplemented in STAAD.

18B.2.3 Compression  

The allowable compressive stress for columns, except those fabricated fromaustenitic stainless steel shall be as required by NF-3322.1(c)(1). The allowablecompressive stress for columns fabricated from austenitic stainless steel shall be asrequired by NF-3322.1(c)(2). The allowable compressive stress for memberelements other than columns constructed by any material, including austeniticstainless steel, shall be as required by NF-3322.1(c)(3).

a. Gross Sections of Columns, except those fabricated of austenitic stainlesssteel:

1. On gross section of axially loaded compression members, when (Kl/r)< C

c,

Where:

2. When (Kl/r) > Cc,

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3. When (Kl/r) > 120,

b. Gross sections of columns fabricated from Austenitic Stainless steel:

1. When (Kl/r) ≤ 120,

2. When (Kl/r) > 120,

c. Member elements other than columns:

1. For Plate Girder Stiffeners, Fa= 0.60·F

y2. For webs of rolled shapes, F

a= 0.75·F

y

The above clauses are applicable only when the width-thickness ratio of theelement satisfies all the sub-sections of NF-3322.2(d).

If the above-mentioned clauses are not satisfied,

a. For un-stiffened compression element, a reduction factor, Qs, is introduced.

Detailed values of Qsfor different shapes are given in NF-3322.2(e)(2)(a) to

NF-3322.2(e)(2)(d).

b. For stiffened compression element, a reduced effective width, be, is

introduced.

1. For the flanges of square and rectangular sections of uniform thickness:

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2. For other uniformly compressed elements:

Consequently, a reduction factor, Qa, equal to the effective area divided by

the actual area is introduced.

Combining both these factors, allowable stress for axially loadedcompression members containing stiffened or un-stiffened elements shallnot exceed

Where:

18B.2.4 Bending Stress  

Allowable bending stress for tension and compression for a structural member, asgiven in NF-3322.1(d) is:

a. Along Major Axis:

1. For Compact Sections, tension and compression on extreme fibres ofcompact hot rolled or built-up members symmetrical about and loaded in theplane of their minor axes and meeting the requirements of Subsection NFshall result in a maximum bending stress:

Fb= 0.66*F

yIf meeting the requirements of this member of:

a. Width-thickness ratio of unstiffened projecting elements of the compressionflange shall not exceed 65/√F

y.

b. Width-thickness ratio of stiffened elements of the compression flange shallnot exceed 190/√F

y.

c. The depth-thickness ratio of the web shall not exceed

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d/t = (640/√Fy)[1 – 3.74(f

a/Fy)] when f

a/Fy<=0.16            

d/t = 257/√Fywhen f

a/Fy> 0.16     

d. The laterally unsupported length of the compression flange of members otherthan box-shaped members shall not exceed the value of 76b

f/√F

ynor

20000/(d/Af)Fy.

2. For noncompact and slender elements, NF-3322.1(d)(5) and NF-3322.1(d)(3) are followed respectively.

3. For box-type flexural members, maximum bending stress is:

Fb= 0.60*F

yb. Along Minor Axis:

1. For doubly symmetrical members (I shaped) meeting the requirements of NF-3322.1(d)(1)(a) and (b), maximum tensile and compressive bending stressshall not exceed:

Fb= 0.75*F

y2. For doubly symmetrical members (I shaped) meeting the requirements of NF-

3322.1(d)(1)(a), except where bf/2tfexceeds 65/√F

ybut is less than

95/√Fy, maximum tensile and compressive bending stress shall not exceed:

Fb= F

y[1.075 – 0.005(b

f/2tf)√F

y]

18B.2.5 Combined Interaction Check  

Members subjected to both axial compression and bending stresses areproportioned to satisfy

and

when fa/Fa> 0.15,

otherwise

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It should be noted that during code checking or member selection, if fa/Faexceeds

unity, the program does not compute the second and third part of the formula,because this would result in a misleadingly liberal ratio. The value of thecoefficient Cm is taken as 0.85 for side-sway and 0.6 - 0.4·(M1/M2), but not lessthan 0.4 for no side-sway.

Members subjected to both axial tension and bending stress are proportioned tosatisfy

18B.2.6 Shear Stress  

Allowable shear stress on the gross section [ref. NF-3322.6(e)(2)] is calculated as

Where:

, when Cv< 0.8

, when Cv> 0.8

, when a/h < 1.0

, when a/h > 1.0

For actual shear on the web, the gross section is taken as the product of the totaldepth and the web thickness. For shear on the flanges, the gross section is takenas the total flange areas.

18B.3 Member Property Specification

For specification of member properties, the specified steel section available in SteelSection Library of STAAD may be used namely – I-shaped section, Channel, Tee,HSS Tube, HSS Pipe, Angle, Double Angle, Double Channel section. 

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Member properties may also be specified using the User Table facility except for theGeneral and Prismatic member.

For more information on these facilities, refer to Section 1.7 the STAAD TechnicalReference Manual.

18B.4 Design Parameters

The program contains a large number of parameter names which are required toperform design and code checks. These parameter names, with their default values,are listed in the following table.

The default parameter values have been selected such that they are frequently usednumbers for conventional design. Depending on the particular design requirementsfor an analysis, some or all of these parameter values may have to be changed toexactly model the physical structure. For example, by default the KZ value (k valuein local z-axis) of a member is set to 1.0, while in the real structure it may be 1.5. Inthat case, the KZ value in the program can be changed to 1.5, as shown in the inputinstruction (Section 5). Similarly, the TRACK value of a member is set to 0.0, whichmeans no allowable stresses of the member will be printed. If the allowablestresses are to be printed, the TRACK value must be set to 1.0.    

ParameterName

Default Value Description

CODE - Must be specified as NF30001989.

Design Code to follow.

See section 5.48.1 of theTechnical Reference Manual.

CAN 0 Used for Deflection Check only.

0 = Deflection check based onthe principle that maximumdeflection occurs within the spanbetween DJ1 and DJ2.

1 = Deflection check based onthe principle that maximumdeflection is of the cantilever

Table 18B.1 - ASME NF 3000 Design Parameters

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ParameterName

Default Value Description

type

CB 1.0 Bending coefficient dependentupon moment gradient

0.0 = CB is calculated itself

Any other user-defined value isaccepted.

CT 0.75 Reduction Coefficient incomputing effective net area ofan axially loaded tensionmember. [Refer NF-3322.8(c)(1)(d)]

CMY

CMZ

0.85 forsidesway andcalculated forno sidesway

Cm value in local y & z axes

DFF None(Mandatory fordeflectioncheck)

"Deflection Length" / Maximumallowable local deflection

DJ1 Start Jointof member

Joint No. denoting starting pointfor calculation of "DeflectionLength"

DJ2 End Joint ofmember

Joint No. denoting end point forcalculation of "Deflection Length"

DMAX 45 inch Maximum allowable depth, incurrent units. Used only with theMEMBER SELECTION command.

DMIN 0.0 inch Minimum allowable depth, incurrent units. Used only with theMEMBER SELECTION command.

FYLD 36 KSI Yield strength of steel in current

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ParameterName

Default Value Description

units.

FU 60 KSI Ultimate tensile strength of steelin current units.

KY 1.0 K value in local y-axis. Usually,this is minor axis.

KZ 1.0 K value in local z-axis. Usually,this is major axis.

LY Member Length Length to calculate slendernessratio for buckling about local Yaxis.

LZ Member Length Same as above except in z-axis(major).

MAIN 0.0 0.0 = check for slenderness

1.0 = suppress slendernesscheck

NSF 1.0 Net Section Factor for tensionmember.

PROFILE None Used in member selection. SeeSection 5.48.1 of the TechnicalReference Manual for details. 

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

STIFF Member lengthor depthwhichever isgreater

Spacing of stiffeners for plategirder design

STYPE 0.0 0.0 = Normal Steel

1.0 = Austenitic Stainless Steel

TMAIN 240 for main Slenderness limit under tension

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ParameterName

Default Value Description

member

300 for “Truss”member

TRACK 0.0 Controls the levels of detail towhich results are reported.

0 = Minimum detail

1 = Intermediate detail level

2 = Maximum detail

UNB Member Length Unsupported length of thebottom* flange for calculatingallowable bending compressivestress. Will be used only ifflexural compression on thebottom flange.

UNT Member Length Unsupported length of the top*flange for calculating allowablebending compressive stress. Willbe used only if flexuralcompression on the top flange.

18B.5 Code Checking and Member Selection

Both code checking and member selection options are available with the ASME NF-3000 1989 code.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

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18B.6 Example  

A cantilever beam of length 100 inch is loaded at its free end with 5 kipcompressive load and a uniformly distributed load of 1 kip/inch over the wholespan. The beam is assigned with B571806 steel member and is designed inaccordance with ASME NF3000 1989.

The corresponding input of STAAD input editor file is shown as below:

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 18-JUN-08

END JOB INFORMATION

JOINT COORDINATES

1 0 0 0; 2 360 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 29000

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

1 TABLE ST B571806

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

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JOINT LOAD

2 FX -5

MEMBER LOAD

1 UNIGY -1.0 0 100

PERFORMANALYSIS

PRINT SUPPORT REACTION

PARAMETER 1

CODENF3000 1989

STYPE 1 ALL

FYLD 36 ALL

KY 0.75 ALL

KZ 0.75 ALL

FU 58 ALL

NSF 0.9 ALL

CB 0 ALL

TRACK 2 ALL

CHECK CODE ALL

FINISH

The corresponding TRACK 2 output is as follows:STAAD.PRO CODE CHECKING - ( ASME NF3000-89) v1.0********************************************

ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/FX MY MZ LOCATION

=======================================================================

1 ST B571806 (AISC SECTIONS)PASS SHEAR Y 0.770 1

5.00 C 0.00 5000.00 0.00|-----------------------------------------------------------------------------|| SLENDERNESS CHECK: ACTUAL RATIO: 75.08 ALLOWABLE RATIO: 200.00 || ALLOWABLE STRESSES: (UNIT - KIP INCH) || AXIAL: 1.13E+01 FCZ: 2.08E+01 FCY: 2.31E+01 FTZ: 2.16E+01 FTY: 2.31E+01 || SHEAR: 5.18E+00 || ACTUAL STRESSES: (UNIT - KIP INCH) || AXIAL: 1.06E-01 FBZ: 5.86E+00 FBY: 0.00E+00 SHEAR: 3.99E+00 ||-----------------------------------------------------------------------------|| SECTION PROPERTIES: (UNIT - INCH) |

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| AXX: 47.00 AYY: 25.08 AZZ: 15.00 RZZ: 22.80 RYY: 3.60 || SZZ: 853.77 SYY: 67.54 ||-----------------------------------------------------------------------------|| PARAMETER: (UNIT - KIP INCH) || KL/R-Z: 11.84 KL/R-Y: 75.08 UNL: 360.0 CMZ: 1.00 CMY: 1.00 || CB: 1.75 FYLD: 36.00 FU: 58.00 NET SECTION FACTOR: 0.90 || CT: 0.75 STEEL TYPE: 1.0 ||-----------------------------------------------------------------------------|| CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS KIP -INCH) || CLAUSE RATIO LOAD FX VY VZ MZ MY || TENSION 0.005 1 5.00E+00 - - - - || COMPRESSION 0.009 1 5.00E+00 - - - - || COMP&BEND 0.290 1 5.00E+00 - - 5.00E+03 0.00E+00 || TEN&BEND 0.000 1 5.00E+00 - - 5.00E+03 0.00E+00 || SHEAR-Y 0.770 1 - 1.00E+02 - - - || SHEAR-Z 0.000 1 - - 0.00E+00 - - ||-----------------------------------------------------------------------------|

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ASME NF 3000 - 2004 Code18C.1 General Comments

For steel design, STAAD compares the actual stresses with the allowable stresses asdefined by the American Society of Mechanical Engineers – Nuclear Facility (ASMENF) Code. The ASME NF-3000 1998 Code is used as the basis of this design.

A brief description of some of the major allowable stresses is described herein.

18C.2 Design Process

The design process follows the following design checks.

1. Slenderness

2. Tension

3. Compression

4. Bending Stress

5. Combined Interaction Check

6. Shear Stress

Each one of the checks are described in the following sections.

When a design is performed, the output file the reports the maximum utilizationfrom all of the checks.

18C.2.1 Slenderness  

As per NF-3322.2(c), the slenderness ratio KL/r of compression members shall notexceed 200, and the slenderness ratio L/r of tension members, preferably shouldnot exceed 240 for main members and 300 for lateral bracing members and othersecondary members. The default limit for TRUSS members in Tension is set at 300.

18C.2.2 Tension  

Allowable tensile stress on the Net section is calculated as (0.60*Fy), but not more

than (0.5*Fu) on the Effective Net area.

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The Net Area (An) shall be determined in accordance with NF-3322.8(c)(1) - (a),

(b) and (c), and the NSF parameter can be utilized for that.

The Effective Net Area (Ae) of axially loaded tension members, where the load is

transmitted by bolts through some but not all of the cross-sectional elements ofthe member, shall be computed from the formula (ref. NF-3322.8(c)(1)(d)),

Ae= C

t* An

Unless otherwise specified, the default value of the CT parameter is set as 0.75.

The value of CT parameter for other conditions is described at section NF-3322.8(c)(1)(d)(1), (2) and (3).

The provisions for Pin-connected and Threaded tensile member are notimplemented in STAAD.

18C.2.3 Compression  

The allowable compressive stress for columns, except those fabricated fromaustenitic stainless steel shall be as required by NF-3322.1(c)(1). The allowablecompressive stress for columns fabricated from austenitic stainless steel shall be asrequired by NF-3322.1(c)(2). The allowable compressive stress for memberelements other than columns constructed by any material, including austeniticstainless steel, shall be as required by NF-3322.1(c)(3).

a. Gross Sections of Columns, except those fabricated of austenitic stainlesssteel:

1. On gross section of axially loaded compression members, when (Kl/r)< C

c,

Where:

2. When (Kl/r) > Cc,

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3. When (Kl/r) > 120,

b. Gross sections of columns fabricated from Austenitic Stainless steel:

1. When (Kl/r) ≤ 120,

2. When (Kl/r) > 120,

c. Member elements other than columns:

1. For Plate Girder Stiffeners, Fa= 0.60·F

y2. For webs of rolled shapes, F

a= 0.75·F

y

The above clauses are applicable only when the width-thickness ratio of theelement satisfies all the sub-sections of NF-3322.2(d).

If the above-mentioned clauses are not satisfied,

a. For un-stiffened compression element, a reduction factor, Qs, is introduced.

Detailed values of Qsfor different shapes are given in NF-3322.2(e)(2)(a) to

NF-3322.2(e)(2)(d).

In the case for angles or plates projecting from compression members and forprojecting elements of compression flanges of girder,

When ,

When ,

Where:

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when h/t > 70, otherwise, kc = 1.0.

b. For stiffened compression element, a reduced effective width, be, is

introduced.

1. For the flanges of square and rectangular sections of uniformthickness:

2. For other uniformly compressed elements:

Consequently, a reduction factor, Qa, equal to the effective area divided by

the actual area is introduced.

Combining both these factors, allowable stress for axially loadedcompression members containing stiffened or un-stiffened elements shallnot exceed

Where:

18C.2.4 Bending Stress  

Allowable bending stress for tension and compression for a structural member, asgiven in NF-3322.1(d) is:

a. Along Major Axis:

1. For Compact Sections, tension and compression on extreme fibres ofcompact hot rolled or built-up members symmetrical about and loaded in the

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plane of their minor axes and meeting the requirements of Subsection NFshall result in a maximum bending stress:

Fb= 0.66*F

yIf meeting the requirements of this member of:

a. Width-thickness ratio of unstiffened projecting elements of the compressionflange shall not exceed 65/√F

y.

b. Width-thickness ratio of stiffened elements of the compression flange shallnot exceed 190/√F

y.

c. The depth-thickness ratio of the web shall not exceed

d/t = (640/√Fy)[1 – 3.74(f

a/Fy)] when f

a/Fy<=0.16            

d/t = 257/√Fywhen f

a/Fy> 0.16     

d. The laterally unsupported length of the compression flange of members otherthan box-shaped members shall not exceed the value of 76b

f/√F

ynor

20000/(d/Af)Fy.

2. For noncompact and slender elements, NF-3322.1(d)(5) and NF-3322.1(d)(3) are followed respectively.

3. For box-type flexural members, maximum bending stress is:

Fb= 0.60*F

yb. Along Minor Axis:

1. For doubly symmetrical members (I shaped) meeting the requirements of NF-3322.1(d)(1)(a) and (b), maximum tensile and compressive bending stressshall not exceed:

Fb= 0.75*F

y2. For doubly symmetrical members (I shaped) meeting the requirements of NF-

3322.1(d)(1)(a), except where bf/2tfexceeds 65/√F

ybut is less than

95/√Fy, maximum tensile and compressive bending stress shall not exceed:

Fb= F

y[1.075 – 0.005(b

f/2tf)√F

y]

18C.2.5 Combined Interaction Check

Members subjected to both axial compression and bending stresses are

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proportioned to satisfy

and

when fa/Fa> 0.15,

otherwise

It should be noted that during code checking or member selection, if fa/Faexceeds

unity, the program does not compute the second and third part of the formula,because this would result in a misleadingly liberal ratio. The value of thecoefficient Cm is taken as 0.85 for side-sway and 0.6 - 0.4·(M1/M2), but not lessthan 0.4 for no side-sway.

Members subjected to both axial tension and bending stress are proportioned tosatisfy

18C.2.6 Shear Stress  

Allowable shear stress on the gross section [ref. NF-3322.6(e)(2)] is calculated as

Where:

, when Cv< 0.8

, when Cv> 0.8

, when a/h < 1.0

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, when a/h > 1.0

For actual shear on the web, the gross section is taken as the product of the totaldepth and the web thickness. For shear on the flanges, the gross section is taken asthe total flange areas.

18C.3 Member Property Specification

For specification of member properties, the specified steel section available in SteelSection Library of STAAD may be used namely – I-shaped section, Channel, Tee,HSS Tube, HSS Pipe, Angle, Double Angle, Double Channel section. 

Member properties may also be specified using the User Table facility except for theGeneral and Prismatic member.

For more information on these facilities, refer to Section 1.7 the STAAD TechnicalReference Manual.

18C.4 Design Parameters

The program contains a large number of parameter names which are required toperform design and code checks. These parameter names, with their default values,are listed in the following table.

The default parameter values have been selected such that they are frequently usednumbers for conventional design. Depending on the particular design requirementsfor an analysis, some or all of these parameter values may have to be changed toexactly model the physical structure. For example, by default the KZ value (k valuein local z-axis) of a member is set to 1.0, while in the real structure it may be 1.5. Inthat case, the KZ value in the program can be changed to 1.5, as shown in the inputinstruction (Section 5). Similarly, the TRACK value of a member is set to 0.0, whichmeans no allowable stresses of the member will be printed. If the allowablestresses are to be printed, the TRACK value must be set to 1.0.    

ParameterName

Default Value Description

CODE - Must be specified as NF30001998.

Design Code to follow.

See section 5.48.1 of the

Table 18C.1 - ASME NF 3000 1998 Design Parameters

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ParameterName

Default Value Description

Technical Reference Manual.

CAN 0 Used for Deflection Checkonly.

0 = Deflection check basedon the principle thatmaximum deflection occurswithin the span betweenDJ1 and DJ2.

1 = Deflection check basedon the principle thatmaximum deflection is of thecantilever type

CB 1.0 Bending coefficientdependent upon momentgradient

0.0 = CB is calculated itself

Any other user-definedvalue is accepted.

CMY

CMZ

0.85 for sideswayand calculated forno sidesway

Cm value in local y & z axes

CT 0.75 Reduction Coefficient incomputing effective net areaof an axially loaded tensionmember. [Refer NF-3322.8(c)(1)(d)]

DFF None(Mandatory fordeflection check)

"Deflection Length" /Maximum allowable localdeflection

DJ1 Start Jointof member

Joint No. denoting startingpoint for calculation of"Deflection Length"

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ParameterName

Default Value Description

DJ2 End Joint ofmember

Joint No. denoting end pointfor calculation of "DeflectionLength"

DMAX 45 inch Maximum allowable depth,in current units. Used onlywith the MEMBERSELECTION command.

DMIN 0.0 inch Minimum allowable depth,in current units. Used onlywith the MEMBERSELECTION command.

FYLD 36 KSI Yield strength of steel incurrent units.

FU 60 KSI Ultimate tensile strength ofsteel in current units.

KY 1.0 K value in local y-axis.Usually, this is minor axis.

KZ 1.0 K value in local z-axis.Usually, this is major axis.

LY Member Length Length to calculateslenderness ratio forbuckling about local Y axis.

LZ Member Length Same as above except in z-axis (major).

MAIN 0.0 0.0 = check for slenderness

1.0 = suppress slendernesscheck

NSF 1.0 Net Section Factor fortension member.

PROFILE None Used in member selection.

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ParameterName

Default Value Description

See Section 5.48.1 of theTechnical Reference Manualfor details. 

STIFF Member length ordepth whichever is

greater

Spacing of stiffeners forplate girder design

STYPE 0.0 0.0 = Normal Steel

1.0 = Austenitic StainlessSteel

TMAIN 240 for mainmember

300 for “Truss”member

Slenderness limit undertension

TRACK 0.0 Controls the levels of detailto which results arereported.

0 = Minimum detail

1 = Intermediate detail level

2 = Maximum detail

RATIO 1.0 Permissible ratio of theactual to allowable stresses.

UNB Member Length Unsupported length of thebottom* flange forcalculating allowablebending compressive stress.Will be used only if flexuralcompression on the bottomflange.

UNT Member Length Unsupported length of thetop* flange for calculating

906— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 917: International Codes v8i

ParameterName

Default Value Description

allowable bendingcompressive stress. Will beused only if flexuralcompression on the topflange.

Notes

1. All values are entered in the current units.

2. The parameters DMAX and DMIN are only used with the MEMBER SELECTIONcommand.

18C.5 Code Checking and Member Selection

Both code checking and member selection options are available with the ASME NF-3000 1998 code.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

18C.6 Example  

A cantilever beam of length 100 inch is loaded at its free end with 5 kipcompressive load and a uniformly distributed load of 1 kip/inch over the wholespan. The beam is assigned with B571806 steel member and is designed inaccordance with ASME NF3000 1998.

The corresponding input of STAAD input editor file is shown as below:

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 18-JUN-08

END JOB INFORMATION

International Design Codes Manual — 907

Page 918: International Codes v8i

UNIT INCHES KIP

JOINT COORDINATES

1 0 0 0; 2 100 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 29000

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

1 TABLE ST B571806

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

JOINT LOAD

2 FX -5

MEMBER LOAD

1 UNIGY -1.0 0 100

PERFORMANALYSIS

PARAMETER 1

CODENF3000 1998

STYPE 1 ALL

FYLD 36 ALL

KY 0.75 ALL

908— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 919: International Codes v8i

KZ 0.75 ALL

FU 58 ALL

NSF 0.9 ALL

CT 0.85 ALL

CB 0 ALL

TRACK 2 ALL

CHECK CODE ALL

FINISH

The corresponding TRACK 2 output is as follows:STAAD.PRO CODE CHECKING - ( ASME NF3000-98) v1.0********************************************

ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/FX MY MZ LOCATION

=======================================================================

1 ST B571806 (AISC SECTIONS)PASS SHEAR Y 0.635 1

5.00 C 0.00 5000.00 0.00|-----------------------------------------------------------------------------|| SLENDERNESS CHECK: ACTUAL RATIO: 20.85 ALLOWABLE RATIO: 200.00 || ALLOWABLE STRESSES: (UNIT - KIP INCH) || AXIAL: 1.20E+01 FCZ: 2.22E+01 FCY: 2.31E+01 FTZ: 2.22E+01 FTY: 2.31E+01 || SHEAR: 6.28E+00 || ACTUAL STRESSES: (UNIT - KIP INCH) || AXIAL: 1.06E-01 FBZ: 5.86E+00 FBY: 0.00E+00 SHEAR: 3.99E+00 ||-----------------------------------------------------------------------------|| SECTION PROPERTIES: (UNIT - INCH) || AXX: 47.00 AYY: 25.08 AZZ: 15.00 RZZ: 22.80 RYY: 3.60 || SZZ: 853.77 SYY: 67.54 ||-----------------------------------------------------------------------------|| PARAMETER: (UNIT - KIP INCH) || KL/R-Z: 3.29 KL/R-Y: 20.85 UNL: 100.0 CMZ: 1.00 CMY: 1.00 || CB: 1.75 FYLD: 36.00 FU: 58.00 NET SECTION FACTOR: 0.90 || CT: 0.85 STEEL TYPE: 1.0 ||-----------------------------------------------------------------------------|| CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS KIP -INCH) || CLAUSE RATIO LOAD FX VY VZ MZ MY || TENSION 0.005 1 5.00E+00 - - - - || COMPRESSION 0.009 1 5.00E+00 - - - - || COMP&BEND 0.272 1 5.00E+00 - - 5.00E+03 0.00E+00 || TEN&BEND 0.000 1 5.00E+00 - - 5.00E+03 0.00E+00 || SHEAR-Y 0.635 1 - 1.00E+02 - - - || SHEAR-Z 0.000 1 - - 0.00E+00 - - ||-----------------------------------------------------------------------------|

International Design Codes Manual — 909

Page 920: International Codes v8i

ASME NF 3000 - 2004 Code18D.1 General Comments

For steel design, STAAD compares the actual stresses with the allowable stressesas defined by the American Society of Mechanical Engineers – Nuclear Facility(ASME NF) Code. The ASME NF-3000 2004 Code is used as the basis of thisdesign.

A brief description of some of the major allowable stresses is described herein.

Note: This feature requires STAAD.Pro V8i (SELECTseries 2) NRC (build20.07.07.30) or higher.

18D.2 Design Process

The design process follows the following design checks.

1. Slenderness

2. Tension

3. Compression

4. Bending Stress

5. Combined Interaction Check

6. Shear Stress

Each one of the checks is described in the following sections.

When a design is performed, the output file the reports the maximum utilizationfrom all of the checks.

18D.2.1 Slenderness  

As per NF-3322.2(c), the slenderness ratio KL/r of compression members shall notexceed 200, and the slenderness ratio L/r of tension members, preferably shouldnot exceed 240 for main members and 300 for lateral bracing members and othersecondary members. The default limit for TRUSS members in Tension is set at 300.

910— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 921: International Codes v8i

18D.2.2 Tension

Allowable tensile stress on the Net section is calculated as (0.60·Fy), but not more

than (0.5·Fu) on the Effective Net area.

The Net Area (An) shall be determined in accordance with NF-3322.8(c)(1) - (a),

(b) and (c), and the NSF parameter can be utilized for that.

The Effective Net Area (Ae) of axially loaded tension members, where the load is

transmitted by bolts through some but not all of the cross-sectional elements of themember, shall be computed from the formula (ref. NF-3322.8(c)(1)(d)),

Ae= C

t· A

n

Unless otherwise specified, the default value of the CT parameter is set as 0.75.

The value of CT parameter for other conditions is described at section NF-3322.8(c)(1)(d)(1), (2) and (3).

The provisions for Pin-connected and Threaded tensile member are notimplemented in STAAD.

18D.2.3 Compression  

The allowable compressive stress for columns, except those fabricated fromaustenitic stainless steel shall be as required by NF-3322.1(c)(1). The allowablecompressive stress for columns fabricated from austenitic stainless steel shall be asrequired by NF-3322.1(c)(2). The allowable compressive stress for memberelements other than columns constructed by any material, including austeniticstainless steel, shall be as required by NF-3322.1(c)(3).

A. Gross Sections of Columns, except those fabricated of austenitic stainlesssteel:

1. On gross section of axially loaded compression members, when (Kl/r) ≤Cc,

Fa= [1 - (Kl/r)2/(2·C

c2)]F

y/ {5/3 + [3(Kl/r)/(8·C

c)] -

[(Kl/r)3/(8·Cc3)]}

(Eq. A1)

Where:

International Design Codes Manual — 911

Page 922: International Codes v8i

Cc= [(2·π2E)/F

y]1/2

2. When (Kl/r) > Cc,

Fa= 12·π2E/[23(kL/r)2]

(Eq. A2)

3. When (Kl/r) > 120,

Fas= F

a[(Eq.A1) or (Eq. A2)]/{1.6 - [l/(200r)]}

B. Gross sections of columns fabricated from Austenitic Stainless steel:

1. When (Kl/r) ≤ 120,

Fa= F

y[0.47 - (Kl/r)/444]

2. When (Kl/r) > 120,

Fa= F

y[0.40 - (Kl/r)/600]

C. Member elements other than columns:

1. For Plate Girder Stiffeners,

Fa= 0.60·F

y

2. For webs of rolled shapes,

Fa= 0.75·F

y

The above clauses are applicable only when the width-thickness ratio of theelement satisfies all the sub-sections of NF-3322.2(d)..

If the above-mentioned clauses are not satisfied,

a. For un-stiffened compression element,  

A reduction factor Qsis introduced. Detailed values of Q

sfor different shapes

are given in NF-3322.2(e)(2)(a) to NF-3322.2(e)(2)(d).

In the case for angles or plates projecting from compression members andfor projecting elements of compression flanges of girder,

When 95/(Fy/kc)1/2 < b/t < 195/(F

y/kc)1/2, Q

s= 1.293 -

0.00309·(b/t)·(Fy/kc)1/2

When b/t > 195/(Fy/kc)1/2, Q

s= 26,200·kc/[F

y(b/t)2)]

912— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 923: International Codes v8i

Where:

kc = 4.05/[(h/t)0.46] if h/t > 70, otherwise kc = 1.0.

b. For stiffened compression element,  

A reduced effective width beis introduced.

1. For the flanges of square and rectangular sections of uniformthickness: 

be= 253·t/√(f){1 - 50.3/[(b/t)√(f)]} ≤ b

2. For other uniformly compressed elements:  

be= 253·t/√(f){1 - 44.3/[(b/t)√(f)]} ≤ b

Consequently, a reduction factor Qais introduced and is equal to the

effective area divided by the actual area. Combining both these factors,allowable stress for axially loaded compression members containing stiffenedor unstiffened elements shall not exceed

Fa= Q

sQa[1 - (Kl/r)2/(2·C

c2)]F

y/ {5/3 + [3(Kl/r)/(8·C

c)] -

[(Kl/r)3/(8·Cc3)]}

Where:

C'c= [(2·π2E)/(Q

sQaFy)]1/2

18D.2.4 Bending Stress  

Allowable bending stress for tension and compression for a structural member, asgiven in NF-3322.1(d) is:

A. Along Major Axis:

1. For Compact Sections, tension and compression on extreme fibres ofcompact hot rolled or built-up members symmetrical about and loadedin the plane of their minor axes and meeting the requirements ofSubsection NF shall result in a maximum bending stress:

Fb= 0.66·F

y

If meeting the requirements of this member of:

International Design Codes Manual — 913

Page 924: International Codes v8i

a. Width-thickness ratio of unstiffened projecting elements of thecompression flange shall not exceed 65/√F

y.

b. Width-thickness ratio of stiffened elements of the compressionflange shall not exceed 190/√F

y.

c. The depth-thickness ratio of the web shall not exceed

d/t = (640/√Fy)[1 – 3.74(f

a/Fy)] when f

a/Fy≤ 0.16

d/t = 257/√Fywhen f

a/Fy> 0.16

d. The laterally unsupported length of the compression flange ofmembers other than box-shaped members shall not exceed thevalue of 76b

f/√F

ynor 20000/(d/A

f)Fy.

2. For noncompact and slender elements, NF-3322.1(d)(5) and NF-3322.1(d)(3) are followed respectively.

3. For box-type flexural members, maximum bending stress is:

Fb= 0.75·F

y

B. Along Minor Axis:

1. For doubly symmetrical members (I shaped) meeting the requirementsof NF-3322.1(d)(1)(a) and (b), maximum tensile and compressivebending stress shall not exceed:

Fb= 0.75·F

y

2. For doubly symmetrical members (I shaped) meeting the requirementsof NF-3322.1(d)(1)(a), except where b

f/2t

f> 65/√F

ybut is less than

95/√Fy, maximum tensile and compressive bending stress shall not

exceed:

Fb= F

y[1.075 – 0.005(b

f/2t

f)√F

y]

18D.2.5 Combined Interaction Check

Members subjected to both axial compression and bending stresses areproportioned to satisfy

914— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 925: International Codes v8i

and

when fa/Fa> 0.15,

otherwise

It should be noted that during code checking or member selection, if fa/Faexceeds

unity, the program does not compute the second and third part of the formula,because this would result in a misleadingly liberal ratio. The value of the coefficientCm is taken as 0.85 for side-sway and 0.6 - 0.4·(M1/M2), but not less than 0.4 forno side-sway.

Members subjected to both axial tension and bending stress are proportioned tosatisfy

18D.2.6 Shear Stress  

Allowable shear stress on the gross section [ref. NF-3322.6(e)(2)] is calculated as

Where:

, when Cv< 0.8

, when Cv> 0.8

, when a/h < 1.0

, when a/h > 1.0

International Design Codes Manual — 915

Page 926: International Codes v8i

For actual shear on the web, the gross section is taken as the product of the totaldepth and the web thickness. For shear on the flanges, the gross section is takenas the total flange areas.

18D.3 Member Property Specification

For specification of member properties, the specified steel section available in SteelSection Library of STAAD may be used namely – I-shaped section, Channel, Tee,HSS Tube, HSS Pipe, Angle, Double Angle, Double Channel section.

Member properties may also be specified using the User Table facility except forthe General and Prismatic member.

For more information on these facilities, refer to Section 1.7 the STAAD TechnicalReference Manual.

18D.4 Design Parameters

The program contains a large number of parameter names which are required toperform design and code checks. These parameter names, with their defaultvalues, are listed in the following table.

The default parameter values have been selected such that they are frequentlyused numbers for conventional design. Depending on the particular designrequirements for an analysis, some or all of these parameter values may have to bechanged to exactly model the physical structure. For example, by default the KZvalue (k value in local z-axis) of a member is set to 1.0, while in the real structure itmay be 1.5. In that case, the KZ value in the program can be changed to 1.5, asshown in the input instruction (Section 5). Similarly, the TRACK value of a memberis set to 0.0, which means no allowable stresses of the member will be printed. Ifthe allowable stresses are to be printed, the TRACK value must be set to 1.0.

ParameterName

DefaultValue

Description

CODE - Must be specified as NF3000 2004

Specified design code is followed forcode checking purpose.

Design Code to follow.

See section 5.48.1 of the Technical

Table 18C.2 - ASME NF 3000 2004 Design Parameters

916— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 927: International Codes v8i

ParameterName

DefaultValue

Description

Reference Manual.

CB 1.0 Bending coefficient dependent uponmoment gradient

0.0 = CB is calculated itself

Any other user-defined value isaccepted.

CMY

CMZ

0.85 forsideswayand cal-culated forno side-sway

Cm value in local y & z axes

CT 0.75 Reduction Coefficient in computingeffective net area of an axially loadedtension member. [Refer NF-3322.8(c)(1)(d)]

DFF None

(Mandatoryfor

deflectioncheck)

"Deflection Length" / Maximum allow-able local deflection

DJ1 Start Jointof themember

Joint No. denoting starting point forcalculation of "Deflection Length"

DJ2 End Jointof themember

Joint No. denoting end point for cal-culation of "Deflection Length"

DMAX 45 inch Maximum allowable depth

DMIN 0.0 inch Minimum allowable depth

International Design Codes Manual — 917

Page 928: International Codes v8i

ParameterName

DefaultValue

Description

FYLD 36 KSI Yield strength of steel in currentunits.

FU 60 KSI Ultimate tensile strength of steel incurrent units.

KY 1.0 K value in local y-axis. Usually, this isminor axis.

KZ 1.0 K value in local z-axis. Usually, this ismajor axis.

LY MemberLength

Length to calculate slenderness ratiofor buckling about local Y axis.

LZ MemberLength

Same as above except in z-axis(major).

MAIN 0.0 0.0 = check for slenderness

1.0 = suppress slenderness check

NSF 1.0 Net Section Factor for tensionmember.

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

STIFF Memberlength ordepth

whicheveris greater

Spacing of stiffeners for plate girderdesign

STYPE 0.0 0.0 = Normal Steel

1.0 = Austenitic Stainless Steel

TRACK 0.0 Controls the levels of detail to whichresults are reported.

0. Minimum detail

1. Intermediate detail level

918— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 929: International Codes v8i

ParameterName

DefaultValue

Description

2. Maximum detail

UNB MemberLength

Unsupported length of the bottom*flange for calculating allowable bend-ing compressive stress. Will be usedonly if flexural compression on thebottom flange.

UNT MemberLength

Unsupported length of the top*flange for calculating allowable bend-ing compressive stress. Will be usedonly if flexural compression on thetop flange.

Notes

1. All values are entered in the current units.

2. The parameters DMAX and DMIN are only used with the MEMBER SELECTIONcommand.

18D.5 Code Checking and Member Selection

Both code checking and member selection options are available with the ASME NF-3000 2004 code.

Refer to Section 2.5 of the Technical Reference Manual for general information onCode Checking. Refer to Section 5.48.2 of the Technical Reference Manual fordetails the specification of the Code Checking command.

Refer to Section 2.6 of the Technical Reference Manual for general information onMember Selection. Refer to Section 5.48.3 of the Technical Reference Manual fordetails the specification of the Member Selection command.

18D.6 Example  

A cantilever beam of length 100 inch is loaded at its free end with 5 kipcompressive load and a uniformly distributed load of 1 kip/inch over the wholespan. The beam is assigned with B571806 steel member and is designed inaccordance with ASME NF3000 2004.

The corresponding input of STAAD input editor file is shown as below:

International Design Codes Manual — 919

Page 930: International Codes v8i

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 18-JUN-08

END JOB INFORMATION

UNIT INCHES KIP

JOINT COORDINATES

1 0 0 0; 2 100 0 0;

MEMBER INCIDENCES

1 1 2;

DEFINEMATERIAL START

ISOTROPIC STEEL

E 29000

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINEMATERIAL

MEMBER PROPERTYAMERICAN

1 TABLE ST B571806

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

JOINT LOAD

2 FX -5

MEMBER LOAD

1 UNIGY -1.0 0 100

PERFORMANALYSIS

PARAMETER 1

920— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 931: International Codes v8i

CODENF3000 2004

STYPE 1 ALL

FYLD 36 ALL

KY 0.75 ALL

KZ 0.75 ALL

FU 58 ALL

NSF 0.9 ALL

CT 0.85 ALL

CB 0 ALL

TRACK 2 ALL

CHECK CODE ALL

FINISH

The corresponding TRACK 2 output is as follows:

STAAD.PRO CODE CHECKING - ( ASME NF3000-04)v1.0

********************************************

ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOAD-ING/

FX MY MZ LOCA-TION

=======================================================================

1 ST B571806 (AISC SECTIONS)PASS NF-3322.1(b) 0.635 1

5.00 C 0.00 5000.00 0.00|-----------------------------------------------------------------------------|| SLENDERNESS CHECK: ACTUAL RATIO: 20.85 ALLOWABLE RATIO: 200.00

|| ALLOWABLE STRESSES: (UNIT - KIP INCH)

|| AXIAL: 1.20E+01 FCZ: 2.22E+01 FCY: 2.31E+01 FTZ: 2.22E+01 FTY:2.31E+01 || SHEAR: 6.28E+00

|| ACTUAL STRESSES: (UNIT - KIP INCH)

|| AXIAL: 1.06E-01 FBZ: 5.86E+00 FBY: 0.00E+00 SHEAR: 3.99E+00

|

International Design Codes Manual — 921

Page 932: International Codes v8i

|-----------------------------------------------------------------------------|| SECTION PROPERTIES: (UNIT - INCH)

|| AXX: 47.00 AYY: 25.08 AZZ: 15.00 RZZ: 22.80 RYY: 3.60

|| SZZ: 853.77 SYY: 67.54

||-----------------------------------------------------------------------------|| PARAMETER: (UNIT - KIP INCH)

|| KL/R-Z: 3.29 KL/R-Y: 20.85 UNL: 100.0 CMZ: 1.00 CMY:1.00 || CB: 1.75 FYLD: 36.00 FU: 58.00 NET SECTION FACTOR: 0.90

|| CT: 0.85 STEEL TYPE: 1.0

||-----------------------------------------------------------------------------|| CRITICAL LOADS FOR EACH CLAUSE CHECK (UNITS KIP -INCH)

|| CLAUSE RATIO LOAD FX VY VZ MZMY |

| TENSION 0.005 1 5.00E+00 - - -- |

| COMPRESSION 0.009 1 5.00E+00 - - -- |

| COMP&BEND 0.272 1 5.00E+00 - - 5.00E+030.00E+00 || TEN&BEND 0.000 1 5.00E+00 - - 5.00E+030.00E+00 || SHEAR-Y 0.635 1 - 1.00E+02 - -

- || SHEAR-Z 0.000 1 - - 0.00E+00 -

- ||-----------------------------------------------------------------------------|

922— STAAD.Pro

ASME NF 3000 - 2004 Code

Page 933: International Codes v8i

Section 19

Norwegian Codes

International Design Codes Manual — 923

Page 934: International Codes v8i

924— STAAD.Pro

Page 935: International Codes v8i

Norwegian Codes - Steel Design per NS 3472 /NPD

19A.1 - General Notes

This user manual presents a description of the design basis, parameters and theoryapplied to STAAD.Pro for performing code checks according to NS 3472 ref. [1]and NPD ref. [5]. The code checks include:

l stability check (buckling)

l lateral buckling check

l yield check (von Mises)

l stability check including local plate buckling of un-stiffened pipe walls accord-ing to NPD

The code check is available for the following cross-section types:

l wide flange profiles (HEA, HEB, IPE etc.)

l pipe (OD xx ID xx)

l tube (RHS, HUP)

l channel

l angle type (only RA)

l rectangular massive box (prismatic)

l user table (wide flange, I-sections, tapered I, tube, channel and RA angle)

The code check is not available for the following cross-section types:

l Double angles

l Tapered tubes

l Prismatic sections with too few section parameters defined

l Other sections that are not in the ‘available’ list above

Please note the following:

l NS 3472 and NPD code checking covered in this document are availablethrough two separate STAAD.Pro Code check packages.

International Design Codes Manual — 925

Page 936: International Codes v8i

l This document is not a lecture in use of NS 3472 or NPD. This documentexplains how, and which parts of, the Norwegian steel codes that have beenimplemented in STAAD.Pro.

l When L-sections are used, the Code Check requires RA angle definition.

l Weld design is not included in the Norwegian code checks.

l The prismatic section defined in the code check (rectangular massive box) isnot identical to the general prismatic profile defined in the STAAD.Pro anal-ysis package.

EDR does not accept any liability for loss or damage from or in consequence foruse of the program.

Nomenclature

NS - refers to NS 3472 ref. [1]

NS2 - refers to NS 3472 ref. [6]

NPD - refers to NPD94 ref. [5]

References

1. NS 3472 3.utg. 2001

Prosjektering av stålkonstruksjoner

Beregning og dimensjonering

2. STAAD.Pro Technical Reference Manual, Release 2002

3. NS 3472 1.utg. 1973

Prosjektering av stålkonstruksjoner

Beregning og dimensjonering

4. Roark &Young`s 5th edition

5. NPD utg. 1994

Veiledning om utforming, beregning og dimensjonering avstålkonstruksjoner. Sist

endret 1. oktober 1993.

926— STAAD.Pro

Norwegian Codes - Steel Design per NS 3472 / NPD

Page 937: International Codes v8i

6. NS 3472 2.utg.1984

Prosjektering av stålkonstruksjoner

Beregning og dimensjonering

19A.2 - Basis for Code Checking

19A.2.1 General

This section presents general information regarding the implementation of theNorwegian codes of practice for structural steel design. This manual describes theprocedures and theory used for both NS and NPD.

In general NS is used for all cross sections and shapes listed in section 1 of thismanual. An exception is the treatment and check of pipe members in framedstructures. NS does not give specific details about the treatment of pipes. Section3.4 explains how this is adopted when NS is selected for code checking.

The NPD however have a more thorough check of pipe members, and consider theeffect of local buckling of the pipe wall in conjunction with the stability check. Inaddition, the NPD code gives joint capacity formulae for brace to chord connectionsfor pipe members.

The design philosophy and procedural logistics are based on the principles ofelastic analysis and ultimate limit state design. Two major failure modes arerecognized:

l failure by overstressing

l failure by stability considerations

The following sections describe the salient features of the design approach.Members are proportioned to resist the design loads without exceeding thecharacteristic stresses or capacities and the most economic section is selected onthe basis of the least weight criteria. It is generally assumed that the user will takecare of the detailing requirements like the provision of stiffeners and check the localeffects like flange buckling, web crippling, etc.

The user is allowed complete control over the design process through the use ofthe parameters listed in Table 2.1. Default values of parameters will yieldreasonable results in most circumstances. However, the user should control thedesign and verify results through the use of the design parameters.

International Design Codes Manual — 927

Page 938: International Codes v8i

19A.2.2 Calculation of Forces and Bending Moments

Elastic analysis method is used to obtain the forces and moments for design.Analysis is done for the primary loading conditions and combinations provided bythe user. The user is allowed complete flexibility in providing loadingspecifications and using appropriate load factors to create necessary loadcombinations.

19A.2.3 Members with Axial Forces

For tension only members, axial tension capacity is checked for the ultimate limitstress. For compression members, axial compression capacity is checked inaddition to lateral buckling and ultimate limit stress. The largest slenderness ratio(λ) shall not be greater than 250 according to NS 11.7 Stability is checked as perthe procedure of NS 12.3. The buckling curves of NS fig. 3 have been incorporatedinto the STAAD.Pro code check. The coefficient α (as per NS Table 10) can bespecified in both directions through the use of parameters CY and CZ. In theabsence of parameters CY and /or CZ, default a- value will be according to NStable 11.

19A.2.4 Members with Axial Force and Bending Moments

For compression members with bending, interaction formulae of NS table 12.3.4.2are checked for appropriate loading situation. All compression capacities arecalculated per the procedure of NS 12.3.

The equivalent moment factor β is calculated using the procedure of NS table 12.Two different approaches are used depending upon whether the members cansway or not. Conditions for sidesway and transverse loading can be specifiedthrough the use of parameters SSY and SSZ. For members that cannot sway,without transverse loading, coefficients b are calculated and proper dimensioningmoments are used in the interaction formulae.

19A.2.5 Lateral Buckling

Lateral torsional buckling is checked as per the procedure of NS 12.3.4. Theprocedure for calculation of ideal buckling moment for sections with two axis ofsymmetry has been implemented. The coefficient can be provided by the userthrough the use of parameter CB. In the absence of CB, a value of 1.0 will be used.

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Norwegian Codes - Steel Design per NS 3472 / NPD

Page 939: International Codes v8i

Torsional properties for cross sections (torsional constant and warping constant)are calculated using formulae from NS 3472. This results in slightly conservativeestimates of torsional parameters. The program will automatically select themaximummoment in cases where M

vdis less than M

zd.

19A.2.6 Von Mises Yield Criterion

Combined effect of axial, bending, horizontal/vertical shear and torsional shearstress is calculated at 13 sections on a member and up to 9 critical points at asection. The worst stress value is checked against yield stress divided byappropriate material factor. The von Mises calculates as:

19A.2.7 Material Factor and nominal stresses

The design resistances are obtained by dividing the characteristic material strengthby the material factor.

NS 3472

The material factor default value is 1.10. Other values may be input with the MFparameter. The nominal stresses should satisfy

NPD

The general requirement is according to NPD 3.1.1. For stability the NPD 3.1.1 and3.1.3 requires that the structural coefficient is considered.

Where:

International Design Codes Manual — 929

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Sd= reference stress or load effect resultant

fk= characteristic capacity

fkd= design capacity

γm= material coefficient

γmk= structural coefficient

γmis default set to 1.10.

γmkshall be equal to 1.0 for frames. For pipe members γ

mkis a function of the

reduced slenderness. In the STAAD.Pro implemented NPD code this is calculatedautomatically.

19A.2.8 Code checking according to NPD

The following parts of Chapter 3 in the NPD guidelines have been implemented.

a. Control of nominal stresses. (NPD 3.1.2).

b. Buckling of pipe members in braced frames, including interaction with localshell buckling (NPD 3.2.2, 3.2.3).

c. Buckling of un-stiffened closed cylindrical shells, including interaction withoverall column buckling (NPD 3.4.4, 3.4.6, 3.4.7 and 3.4.9).

d. Joint capacity check for gap as well as for overlap joints (NPD 3.5.2).

Check b) provides the unity check based on the beam-column buckling interactionformulae in NPD 3.2.2. The interaction between global and local buckling due toaxial load and hydrostatic pressure is accounted for through computation of anaxial characteristic capacity to replace the yield stress inn the beam-columnbuckling formulae.

Note: Check b) handles members subjected to axial loads, bending momentsand hydrostatic pressure. In other words, check b) assumes that stressesresulting from shear and torsion are of minor importance, e.g., in jacketbraces.

Check c) provides the unity check based on the stability requirement for un-stiffened cylindrical shells subjected to axial compression or tension, bending,circumferential compression or tension, torsion or shear. The unity check refers to

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the interaction formulae in NPD 3.4.4.1. The stability requirement is given in NPD3.4.7.

19A.2.9 Aluminum Check

STAAD.Pro performs a stability check on aluminum alloys according to bucklingcurve in ECCS (European recommendation for aluminum ally structures 1978). It ispossible to select heat-treated or non heat-treated alloy from the parameter list inthe STAAD.Pro input file.

For heat-treated use CY = CZ = 0.1590, and for non heat-treated use CY = CZ =0.2420.

Tracks 1.0 and 9.0 print buckling curve H for heat-treated, and buckling curve N fornon neat-treated. The yield check is the same as for steel.

19A.3 Design Parameters

Design parameters communicate specific design decisions to the program. They areset to default values to begin with and may be altered to suite the particularstructure.

ParameterName

DefaultValue

Description Reference

CODE none Must be secified as eitherNS3472 for NS or NPD forNPD (NOR may also be usedfor both).

Design Code to follow.

See section 5.48.1 of theTechnical Reference Manual.

BEAM 0.0 Parameter BEAM 1.0 ALLtells the program to calculatevon Mises at 13 sectionsalong each member, and upto 8 points at each section.(Depending on what kind ofshape is used.)

Sec. NS12.2.2

Table 19A.1 - Design Parameters for Norwegian Steel design code

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ParameterName

DefaultValue

Description Reference

Note: Must be set to 1.0

BY 1.0 Buckling length coefficient, βfor weak axis buckling (y-y)(NOTE: BY > 0.0)

Fig. NS 3Sec. NS12.3

BZ 1.0 Buckling length coefficient,β, for strong axis buckling(z-z) (NOTE: BZ > 0.0)

Fig. NS 3Sec. NS12.3

CB 1.0 Lateral buckling coefficient,Y. Used to calculate the idealbuckling moments, M

vi

Sec. NS2A5.5.2Fig. NS2A5.5.2a)-e)

CMY 1.0 Water depth in meters forhydrostatic pressure cal-culation for pipe members

Valid forthe NPDcode only

CMZ 0.49 αLTfor sections in con-

nection with lateral bucklingSec. NS12.3.4 Fig.NS 6.

CY

CZ

Defaultsee NS3472

Buckling curve coefficient, aabout local z-axis (strongaxis). Represent the a, a0, b,c, d curve.

Fig. NS 3Sec. NS12.2 NSTable 11

DMAX 100.0[cm]

Maximum allowable depth ofsteel section.

DMIN 0.0 [cm] Minimum allowable depth ofsteel section.

FYLD 235 Yield strength of steel, fy(St37) [N/mm2 ]

Tab. NS 3

MF 1.1(NS3472)

Material factor / Resistancefactor, γ

m

Sec. NS10.4.2

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ParameterName

DefaultValue

Description Reference

1.15(NPD)

Sec. NPD3.1

RATIO 1.0 Permissible ratio of theactual to allowable stresses.

Sec. NS12.3.4.2

SSY 0.0 0.0 = No sidesway. β cal-culated. > 0.0 = Sidesway inlocal y-axis weak axisβM=SSY

Sec. NS12.3.4Tab. NS12 Sec.NPD3.2.1.4

SSZ 0.0 0.0 = No sidesway. β cal-culated. > 0.0 = Sidesway inlocal y-axis weak axis β

M

Sec. NS12.3.4Tab. NS12 SecNPD3.2.1.4

TRACK 0.0 0.0 = Supress criticalmember stresses. 1.0 = Printall critical member stresses,i.e., DESIGN VALUES 2.0 =Print von Mises stresses. 9.0= Large output, 1 page foreach member. See section 7and Appendix A for completelist of available TRACKs andprint examples.

UNL Memberlength

Effective length for lateralbuckling calculations (spec-ify buckling length). Dis-tance between fork supportsor between effective side sup-ports for the beam

Sec. NS12.3

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The parameter CMY will, when given with negative value, define an inside pressurein pipe members. The pressure corresponds to given water depth in meters.

The parameter CB defines the φ value with respect to calculation of the ideal lateralbuckling moment for single symmetric wide flange profiles, ref. NS app. 5.2.2.

Example

Note: This is a partial example containing only the information pertaining tothe Norwegian steel design code; used at the end of the input file.

* CODE CHECK ACCORDING TONS3472

PARAMETERS

CODENS3472

BEAM 1.0 ALL

FYLD 340 ALL

MF 1.10 ALL

CY 0.49 MEMB 1

CZ 0.49 MEMB 1

BY 0.9 MEMB 1

BZ 0.7 MEMB 1

SSY 1.1 MEMB 1

SSZ 1.3 MEMB 1

CB 0.9 MEMB 1

RATIO 1.0 ALL

TRACK 9.0 ALL

UNIT KNSMETER

LOAD LIST 1

CHECK CODEMEMB 1

FINISH

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19A.4 - Stability Check According to NS 3472

19A.4.1 General Description

The stability check is based on the assumption that both ends of the member arestructural nodes. Buckling lengths and results for member with joints between thestructural nodes have to be evaluated in each separate case.

Effects from local buckling or external hydrostatic pressure on pipes and tubes arenot included.

The general stability criteria is: (ref. NS 12.3)

Buckling

nmax

+ kz× m

z+ k

y× m

y≤ 1

Lateral Buckling

i = z,y

International Design Codes Manual — 935

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19A.4.2 Determination of βzand β

y

The equivalent moment factor β (for z and y) is calculated dependant on momentdistributions as shown in the following table:

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Moment diagram βM(βLT)

βMψ

= 1.8 - 0.7ψ

βM 0

= 1.3

βM 0

= 1.4

Table 19A.2 - β for different moment distributions

The user can override the calculated factor with the following parameters:

βy=SSY

βz=SSZ

19A.4.3 Lateral buckling

The Ideal lateral buckling moment is calculated according to NS2 A5.5.2

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concern double symmetric cross sections where y is given in NS fig. A5.5.2, (inputparameter CB), L = member length for lateral buckling (input parameter UNL), Cwand Ix , see section 5.

For single symmetric cross sections, the ideal lateral buckling moment is

Where:

α = distance from profile CoG to point where the load is acting,assumed to be on top flange.

The φ parameter (ref NS fig. A5.5.2.g) is controlled by the input parameter CB.

Fig A - ψ-koeffisienter for enkel bjelke

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Fig B - ψ-koeffisienter for delvis innspent bjelke

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Fig B - ψ-koeffisienter for tilnærmet fulltinnspente bjelke

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Fig B - ψ-koeffisienter for utraget bjelke med enkel last og fordelt last. Stipledekurver gjelder last på overflens.

19A.4.4 Stability check of pipe members

The stability criteria applied for members with pipe cross section is:

Where:

and are given in NS 5.4.2.

For the print output option TRACK 9.0 KE≡ 1.0 and M

vd≡ M

d

International Design Codes Manual — 941

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19A.4.5 Angle profiles type RA (reverse angle)

The axial contribution to the total interaction ratio is checked according to themodified EECS-method, see NS A5.4.

The stability criterion is:

Where:

Nkyd

and Nkzd

are found from NS 3472 fig. 5.4.la C-curve for y- and z-axis, respectively.

Possible lateral buckling effects and torsional buckling (NS A5.4.5) is not includedin the code check. This has to be evaluated by the user separately.

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19A.4.6 Stability check of members with tapered section

Stability of members with tapered cross section is calculated as described in section3.1. The cross section properties used in the formulae are calculated based on theaverage profile height. (i.e., I

z, Iyvalues are taken from the middle of the member.)

19A.4.7 Lateral buckling for tension members

When compressive stress caused by large bending moment about strong axis isgreater than tension stress from axial tension force, lateral buckling is consideredas defined below.

σa= N/A (+ tension, - compression)

σbz= ± M

z/W

z

Mwarp

= | σa+ σ

b| W

zfor σ

a+ σ

b< 0 (compression)

IR = Mwarp

/Mvd+ M

y,max/Myd≤ 1.0

19A.5 - Stability Check According to NPD

19A.5.1 Buckling of pipe members

Tubular beam-columns subjected to compression and lateral loading or endmoments shall be designed in accordance with NPD 3.2.2

Where:

σc= N/A = axial compressive stress

νmk= structural coefficient

B = bending amplification factor = 1/ (1 - μ), B is taken as the larger ofBzand B

y

Bz= bending amplification factor about the Z-axis

By= bending amplification factor about the Y-axis

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lk= kl

k = effective length factor

fk= characteristic buckling capacity according to NS fig. 5.4.1a, curve

A.

19A.5.1.1 Interaction with local buckling, NPD 3.2.3

If the below conditions are not satisfied, the yield strength will be replaced withcharacteristic buckling stress given in NPD 3.4.

a. members subjected to axial compression and external pressure

b. members subjected to axial compression only

19A.5.2 Calculation of buckling resistance of cylinders

The characteristic buckling resistance is defined in accordance with NPD 3.4.4

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Where:

σa= design axial stress in the shell due to axial forces (tension positive)

σb= design bending stress in the shell due to global bending moment

(tension

positive)

σp= σ

Θ= design circumferential stress in the shell due to external

pressure (tension positive)

τS= design shear stress in the shell due to torsional moments and shear

force.

fea, feb, fepand f

eιare the elastic buckling resistances of curved panels

or circular cylindrical shells subjected to axial compression forces,global bending moments, lateral pressure, and torsional momentsand/or shear forces respectively.

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19A.5.3 Elastic buckling resistance for un-stiffened, closed cyl-inders

The elastic buckling resistance for un-stiffened closed cylinders according to NPD3.4.6 is:

where k is a buckling coefficient dependent on loading condition, aspect ratio,curvature, boundary conditions, and geometrical imperfections. The bucklingcoefficient is:

The values of ψ, ζ and p are given in Table 4.1 for the most important loadingcases.

ψ ζ p

Axial stress 1 0.702 Z

Bending 1 0.702 Z

Torsion and shear force 5.34 0.856 Z0.75 0.6

Lateral pressure 4 1.04 Z0.5 0.6

Hyrdostatic pressure 2 1.04 Z0.5 0.6

Table 19A.3 - Table 4.1 Buckling coefficients for un-stiffened cylin-drical shells

The curvature parameter is defined by

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For long shells the elastic buckling resistance against shear stresses is independent

of shell length. For cases with , the elastic buckling resistance may betaken as:

19A.5.4 Stability requirements

The stability requirement for curved panels and un-stiffened cylindrical shellssubjected to axial compression or tension, bending, circumferential compression ortension, torsion or shear is given by NPD 3.4.7:

σj< f

kd

where the design buckling resistance is

19A.5.5 Column buckling, NPD 3.4.9

For long cylindrical shells it is possible that interaction between shell buckling andoverall column buckling may occur because second-order effects of axialcompression alter the stress distribution as compared to that calculated from lineartheory. It is necessary to take this effect into account in the shell buckling analysiswhen the reduced slenderness of the cylinder as a column exceeds 0,2 according toNPD 3.4.4.1.

σbshall be increased by an additional compressive stress which may be taken as:

Where:

International Design Codes Manual — 947

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λ = slenderness of the cylinder as a column.

B, σa,σband μ are calculated in accordance with NPD 3.2.2.

19A.6 - Yield Check

The yield check is performed at member ends and at 11 equally spacedintermediate sections along the member length.

At each section the following forces are applied:

Fxmax. axial force along member

Fyactual shear in local y-direction at section

Fzactual shear in local z-direction at section

Mxmax. torsional moment along member

Myactual bending about local y-axis at section

Mzactual bending about local z-axis at section

For all profiles other than angle sections absolute values of the stresses are used.For

double symmetric profiles there will always be one stresspoint.

The stresses are calculated in several stress points at each member section. At eachstress

point the von Mises stress is checked as follows:

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Where:

σtot= | σ

x+ σ

by+ σ

bz|

σpstress from hydrostatic pressure.

19A.6.1 Double symmetric wide flange profile

The von Mises stress is checked at 4 stress points as shown in figure below.

Section Properties

Ax, Ix, Iyand I

zare taken from STAAD.Pro database

Ay= h × s Applied in STAAD.Pro print option PRINT MEMBER

STRESSES

Ayand A

zare not used in the code check

International Design Codes Manual — 949

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ref. NS app. C3

Ty= dA × z

Tz= dA × y

General Stress calculation

Stress calculation at selected stress points

In general wide flange profiles are not suitable for large torsional moments. Thereported torsional stresses are indicative only. For members with major torsionalstresses a separate evaluation has to be carried out. Actual torsional stressdistribution is largely dependent on surface curvature at stress point and warpingresistance.

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19A.6.2 Single symmetric wide flange profile and tapered section

The von Mises stress is checked at 9 stress points as shown in figure below.

Section properties

Ax, Ix, Iyand I

zare taken from STAAD.Pro database, except for

tapered sections where these values are calculated for each sectionchecked. (i.e., Iz, Iy values are taken from the middle of the member.)

Ay= h × s Applied in STAAD.Pro print option PRINT MEMBER

STRESSES

Ayand A

zare not used in the code check

ref. NS app. C3

International Design Codes Manual — 951

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Ty= dA × z

Tz= dA × y

General Stress calculation

Stress calculation at selected stress points

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In general wide flange profiles are not suitable for large torsional moments. Thereported torsional stresses are indicative only. For members with major torsionalstresses a separate evaluation has to be carried out. Actual torsional stressdistribution is largely dependent on surface curvature at stress point and warpingresistance.

19A.6.3 Pipe profile

The von Mises stress is checked in 3 stress points as shown in figure below.

Section properties

d = D - 2t

r = 0.5 ( D-t )

International Design Codes Manual — 953

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a = tan-1 Mz/My

Ax = π/4 (D2 - d2)

Ay= A

z= 0.5A

x

Ix= 2I

z=π/32 (D4 - d4)

Iy= I

z= π/64 (D4 - d4)

Note: In the STAAD.Pro analysis package slightly different valuesare used for A

y, Azand I

x, however this has insignificant influence

on the force distribution.

AY= A

z= 0.6A

x

Ix= 2πR3t

Stress calculation at selected stress points

19A.6.4 Tube profile

Tube sections are rectangular or quadratic hollow uniform profiles. Critical stressis checked at 5 locations as shown in figure below.

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Section Properties

International Design Codes Manual — 955

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Stress calculation at selected stress points

The general stress formulation is given in sec. 5.2.

19A.6.5 Channel profile

For channel profiles the von Mises stress is checked at 6 locations as shown in thefigure below.

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International Design Codes Manual — 957

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Cross section properties

Stress calculations at selected stress points

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The general stress formulation is given in sec. 5.2.f

19A.6.6 Angle profile type RA (reverse angle)

For angle profiles the von Mises check is checked at 8 stress points as shown infigure below.

Axes y and z are principal axes.

Axes u and w are local axes.

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Cross section properties

Section forces

The section forces from the STAAD.Pro analysis are about the principle axis y andz.

The second moment of area (Ty L TZ):

Ty= A Z

Tz= A Y

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Stress calculation at selected stress points

An additional torsional moment is calculated based on:

MT= F

yZ4

MT= F

zY4

This torsion moment is included in Mxif F

yand F

Zexist.

Beta-rotation of equal & unequal legged angles

Note: The order of the joint numbers in the member incidence commandspecifies the direction of the local x-axis.

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19A.6.7 Rectangular massive box (prismatic)

Code check of the general purpose prismatic cross section defined in theSTAAD.Pro analysis package is not available. The prismatic section is assumed tobe a rectangular massive box and the von Mises stress is checked at 3 locations asshown in figure below.

Note: Note that ‘b’ may not be much greater than ‘h’. If that is the case, definethe member with h > b and Beta angle 90° instead.

Section Properties

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General Stress Calculation

ref. [4] tab. 20, case 4 at midpoint the largest side i.e., point 2

Stress calculation at selected stress points

19A.7 - Tubular Joint Check, NPD 3.5

For pipe members, punching shear capacity is checked in accordance with the NPDsections 3.5.1 to 3.5.2, except 3.5.2.4. The chord is defined as the member withthe greater diameter in the joint. If the diameters are the same the program selectsthe member with the greater thickness of the two. The chord members must becollinear by 5 degrees.

The punching shear run sequence is performed in two steps. The program will firstidentify all tubular joints and classify them as T type joints (TRACK99). The jointsto be checked will be listed in a file specified in the CODE NPD parameter list,

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below called GEOM1. This file is used as input in the second run. The file is aneditable ACSII file saved under the file name given in the CODE NPD parameter.The TRACK parameter is then set to 98 which directs the program to read from thefile GEOM1 file and use it as input to the second run, i.e., the joint capacitychecking. The program will check the capacity for both chord members entering thejoint. The local y and z moments will be transformed into the plane defined by thejoint itself and the far end joints of the brace and chord, defined as in- and out-ofplane moments.

The ASCII file should be edited to reflect the correct classification of the joints, gap,can or stub dimensions, yield stress and other geometric options if required. Theprogram will not change the brace or chord definition if this is changed or modifiedin the input file GEOM1. See Appendix A page xx for GEOM1 example file.

Joint classification parameters in the file GEOM1 are:

KO K joint overlapped

KG K joint with gap

TY T or Y joint

X X joint

Input example for the classification run.

*CLASSIFICATION OF JOINTS, TRACK 99

UNITSMMNEWTON

PARAMETER

CODENPD GEOM1

FYLD 350 ALL

TRACK 99 ALL

BEAM 1.0 ALL

CHECK CODE ALL

6.1 Static strength of tubular joints

The basic consideration is the chord strength. The required chord wall thicknessshall be

determined when the other dimensions are given.

International Design Codes Manual — 965

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The following symbols are used:

T = Cord wall thickness

t = Brace wall thickness

R = Outer radius of chord

r = Outer radius of brace

Θ = Angel between chord and considered brace

D = Outer diameter of chord

d = Outer diameter of brace

a = Gap (clear distance) between considered brace and nearest load-carrying brace measured along chord outer surface

ß = r/R

g = R/T

g = a/D

fy= Yield stress

Qf= Factor

Qg= See table 6.1

Qu= See table 6.1

Qßd = See table 6.1

N = Design axial force in brace

MIP= Design in-plane bending moment in brace

MOP= Design out-of plane bending moment in brace

Nk= Characteristic axial load capacity of brace (as governed by the

chord strength)

MOPk

= Characteristic out-of-plane bending moment capacity of brace(as governed by the chord strength)

σax= Design axial stress in chord

σIP= Design in-plane bending stress in chord

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σOP= Design out-of-plane bending stress in chord

This section gives design formulae for simple tubular joints without overlap andwithout gussets, diaphragms or stiffeners. Tubular joints in a space frame structureshall satisfy:

Quis given in Table 6.1. Qf is a factor to account for the nominal longitudinal stress

in the chord.

Type of joint andgeometry

Type of load in brace member

Axial In-planebending

Out-of-plane bend-

ing

T and Y 2.5 + 19β 5.0√(γ)β 3.2/(1-0.81β)

X (2.7 + 13β)Qβ

K 0.90(2+21β)Q

β

Table 19A.4 - Values for Qu

International Design Codes Manual — 967

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but in no case shall Qgbe taken as less than 1.0.

When β ≥ 0.9, Qfis set to 1.0. This is also applicable for moment loading. For

cases with tension in the chord, Qf is set to 1.0. This is also applicable for momentloading.

The brace end moments shall be accounted for in the following cases:

a. Out-of-plane bending moment when β > 0.85

b. When the brace acts as a cantilever

c. When the rotational stiffness of the connection is considered in the deter-mination of effective buckling length, and / or the structural coefficient γ

mk= 1.00 for the beam-column design of the brace or chord. See Section 3.1.3.

The characteristic capacity of the brace subjected to in-plane bending momentshall be determined by:

The characteristic capacity of the brace subjected to out-of-plane bending momentshall be determined by:

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For combined axial and bending loads in the brace, the following interactionequation should be satisfied:

For overlapping tubular joints without gussets, diaphragms, or stiffeners, the totalload component normal to the chord, NN, shall not exceed

where (see NPD fig. 3.10)

ll= circumference for that portion of the brace in contact with the chord(actual length)

l = circumference of brace contact with chord, neglecting presence ofoverlap

Nk= characteristic axial load capacity of brace

tw= the lesser of the throat thickness of the overlapping weld or the

thickness t of the thinner brace

l2= length as shown in NPD fig. 3.10

The above formula for the capacity of overlapping joints is valid only for K joints,where compression in a brace is essentially balanced by tension in brace(s) in thesame side of the joint.

19A.8 - Tabulated Results/ TRACKs

This section presents a table with the various TRACKs available with respect to printout from the code check. Example prints and explanation to the information /heading given on the print out is given in Appendix A.

International Design Codes Manual — 969

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TRACKno.

Description

0 Brief print of member utilizations (2 lines for eachmember) sorted with highest utilized members first

1 Based on TRACK 3 with additional information regard-ing stability factors and capacities

2 Simple print of stresses, incl von Mises stress

3 Brief print of member utilizations (2 lines for eachmember)

9 Comprehensive print with detailed information aboutmember and member utilization(one page for eachmember)

99 Used in connection with tubular joint check accordingto NPD. This TRACK identifies tubular joints to bechecked and classifies all members entering the jointas T connection

98 Used in connection with tubular joint check accordingto NPD. This TRACK performs the joint capacity check

49 Prints member end forces for members entering eachjoint (at the end of the member connected to the joint)

31 Prints maximum and minimummember end forces(axial force defines max and min) at member end 1

32 Prints maximum and minimummember end forces(axial force defines max and min) at member end 2

Table 19A.5 - Available TRACKs

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Tracks for member code checking

TRACK = 0.0

International Design Codes Manual — 971

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TRACK = 1.0

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TRACK = 2.0

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TRACK = 3.0

TRACK = 9.0

Member in tension:

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Member in compression:

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Member in compression (pipe - NPD):

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Tracks for joint capacity code checking

TRACK = 99

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TRACK = 98

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Special prints (not code check)

TRACK = 49

TRACK = 31

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TRACK = 32

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Norwegian Codes - Steel Design per NORSOKN-004

19B.1 - General Notes

This section presents a description of the design basis, parameters, and theoryused in STAAD.Pro for performing code checks for tubular members according toNORSOK N-004 Rev 2, October 2004 (hereafter referred to as N-004).

Please note the following:

l The code check is available for the pipe cross sections only.

l The design of conical transitions and joints with joint cans is not performed.

19B.2 Member Resistances

The implementation of the NORSOK N-004 code in STAAD.Pro considers sections4, 5, 6 & 7 in of that document. The details of the various clauses implementedfrom these sections is presented here for member checking and design.

General Provisions

The general safety check is per Section 4. Checks are made to ensure that thedesign action effect (S

d) is less than or equal to the design resistance (R

d):

Sd≤ R

d

The design resistance is evaluated for each condition and this check is applied asdescribed in the following sections.

Steel selection and non destructive testing

Section 5 deals with the choice of “design class” for structural joints andcomponents. The choice of design class will determine the choice of steel grade &quality and also the determination of inspection category for fatigue. The choice ofdesign class (as per Table 5-1 of the code) is left to you and does not have anydirect impact on how STAAD.Pro performs design checks.

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Ultimate Limit States

Clause 6.1 primarily deals with the section of material factors to be used in thevarious conditions or checks. The material factors chosen are dependent on the‘section class’ of a cross section. N-004 does not explicitly specify how to classifyvarious cross sections. Therefore, the section classification is made as given inSection 5.5 of EN 1993-1-1:2005, except when specified explicitly along withmember checks (See Member Subject to Axial Compression).

Also, N-004 does not specify steel grades to be used. Therefore, this STAAD.Prouses the steel grades per EN 1993-1-1:2005 for designs per N-004.

Note: Ring stiffener design to CL. 6.3.6.2 is not included for thisimplementation.

Tubular Members

Clause 6.3.1 deals with the general considerations while using tubular members.

Warning: Only tubular sections can be used with the N-004 code inSTAAD.Pro. A warning is presented for any other section type.

The dimensions of the tubular sections are limited as follows:

l The thickness t ≥ 6 mm.

l The thickness t <150 mm.

l The slenderness ratio of the cross section D/t < 120.

Where D is the diameter and t is the wall thickness of the section.

l The yield strength for tubular member ≤ 500 N/mm2.

If any of these conditions are not met for a member selected for design, a warningwill be issued by the engine and the design of that member is aborted.

Note: N-004 uses ‘Y’ to define the action effects that is in plane and ‘Z’ todefine out of plane effects. This is the opposite to what STAAD uses, where ‘Z’defines the in plane effects and ‘Y’ the out of plane effects. This document willfollow the STAAD.Pro convention for the Z and Y axes.

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The N-004 code also segregates members into those that are subject to hydrostaticpressure and those that are not subject to hydrostatic pressure. The programallows you to specify whether a member is subject to hydrostatic pressure or notand, if so, to specify the hydrostatic pressure for the element. By default theprogram will assume that all members are not subject to any hydrostatic pressure.The design parameter HYD is used to specify the maximum water level with respectto the origin.

If the HYD parameter is specified, the program will take that to be the water leveland will evaluate the pressure distribution on each element assuming a linearincrease in pressure with depth (The density of water is assumed to be 9.8 KN/m3).Also, if the HYD parameter is specified, the program will assume that the hydrostaticloads have not been included in the analysis. For members that are subject to acombination of loads (i.e., bending plus compression) along with a hydrostaticpressure, the design will be done according to Clause 6.3.9 of the code. In theabsence of any hydrostatic pressure on the member the design will be performed inaccordance with Clause 6.3.8 of the code.

19B.2.1 Ultimate Limit State

Axial Tension

Clause 6.3.2 states that tubular members subject to axial tension shall satisfy thefollowing condition:

NSd≤ N

t,Rd= A f

y/γm

Where:

NSd= Design axial force (tension positive)

fy= Characteristic yield strength

A = Cross section area

γm= Default material factor = 1.15

Axial Compression

Clause 6.3.3 states that tubular members subject to axial compression shall satisfythe following condition:

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NSd≤ N

c,Rd= A f

c/γm

Where:

NSd= Design axial force (compression positive)

fc= Characteristic axial compressive strength

γm= Refer to clause 6.3.7

The design axial compressive strength for a member that is not subject to anyhydrostatic pressure will be taken as the smaller of in plane or out of planebuckling strengths determined by the equations given below:

fc= [1.0 - 028 λ2]f

ywhen λ ≤ 1.34

fc= 0.9/λ2 f

ywhen λ > 1.34

λ = √(fcl/fE) = k l/(π i)√(f

cl/E)

Where:

fcl= Characteristic local buckling strength

λ = Column slenderness parameter

fE= Smaller Euler buckling strength in y or z direction.

E = Young's modulus of elasticity = 2.1x105 MPa

k = Effective length factor, refer to Clause 6.3.8.2

l = Longer unbraced length in y or z direction

i = Radius of gyration.

The characteristic local buckling strength is determined from:

fcl= f

ywhen f

y/fcle≤ 0.170 (Plastic yielding)

fcl= [1.047 - 0.274 f

y/fcle] f

ywhen 0.170 < f

y/fcle≤ 1.911

(Elastic/Plastic)

fcl= f

clewhen f

y/fcle> 1.911 (Elastic buckling)

Where:

fcle= 2C

eE t/D (Characteristic elastic local buckling strength)

Ce= 0.3 (Critical elastic buckling coefficient)

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D = Outside diameter

t = wall thickness

For a member that is subject to pure compression, if fy/fcle> 0.170, the section will

be classed as a CLASS 4 (slender section). In such cases, the value of the materialfactor (γ

m) used in the above checks is increased according to equation 6.22 (Cl.

6.3.7) of the code.

Bending

Clause 6.3.4 states that tubular members subject to pure bending alone shallsatisfy:

MSd≤ M

Rd= f

mW/γ

m

Where:

MSd= Design bending moment

fm= Characteristic bending strength

W = Elastic section modulus

γm= Refer to clause 6.3.7

The bending strength fmis calculated as:

fm= Z/W f

ywhen f

yD/(E t) ≤ 0.0517

fm= [1.13 - 2.58 f

yD/(E t)] Z/W f

ywhen 0.0517 < f

yD/(E t) ≤

0.1034

fm= [0.94 - 0.76 f

yD/(E t)] Z/W f

ywhen 0.1034 < f

yD/(E t) ≤

120 fy/E

Shear

Clause 6.3.5 states that tubular members subject to shear shall satisfy:

VSd≤ V

Rd= A f

y/(2√3 γ

m))

Where:

VSd= Design shear force

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fy= Yield strength

A = Cross section area

γm= Default material factor = 1.15

When torsional shear stresses are present, the following condition shall also besatisfied:

MT,Sd

≤ MT,Rd

= 2 Ipfy/(D√3 γ

m))

Where:

MT,Sd

= Design bending moment

Ip= Polar moment of inertia

Hydrostatic Pressure

Clause 6.3.6 states that tubular members subject to an external pressure shallprimarily be checked for hoop buckling. The condition to be satisfied is:

σp,Sd

≤ fh,Rd

= fh/γm)

Where:

σp,Sd

= pSdD/(2 t)

pSd= Design hydrostatic pressure

fh= Characteristic hoop buckling strength

γm)= Refer to clause 6.3.7

The characteristic hoop buckling strength fh, will be calculated as follows:

fh= f

ywhen f

he> 2.44 f

y

fh= 0.7 f

y(fhe/fy)0.4 when 2.44 f

y≥ f

he> 0.55 f

y

fh= f

hewhen f

he≤ 0.55 f

y

The elastic hoop buckling strength fhewill be worked out as follows:

fhe= 2C

hE t/D

Where:

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Ch= 0.44 t/D when μ ≥1.6 D/t

Ch= 0.44 t/D + 0.21 (D/t)3/μ4 when 0.825 D/t ≤ μ <1.6 D/t

Ch= 0.737/(μ - 0.579) when 1.5 ≤ μ < 0.825 D/t

Ch= 0.8 when μ <1.5

μ = Geometric Parameter = L/D√(2 D/t)

L = Length of tubular member between stiffening rings, diaphragms, orend connections.

Combined Axial Tension and Bending (without Hydrostatic Pressure)

Clause 6.3.8.1 states that tubular members subject to axial tension and bendingshall be designed to satisfy the following condition:

Where:

My,Sd

is the design bending moment about the y axis (out-of plane axis)

Mz,Sd

is the design bending moment about the z axis (in plane axis)

NSdis the design axial force

MRdis the moment resistance (as determined by Clause 6.3.4)

Nt,Rd

is the tension capacity of the section (as determined by Clause6.3.2)

Combined Axial Compression and Bending (without Hydrostatic Pres-sure)

Clause 6.3.8.2 states that tubular members subject to axial tension and bendingshall be designed to satisfy the following conditions:

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and

Where:

NSdis the design axial compression

Cmyand C

mzare the reduction factors corresponding to the Y and Z

axes respectively. You may specify a value for these using the CMY andCMZ design parameters, respectively (default is 0.85 for both).

Neyand N

ezare the Euler buckling loads about y & z axes and are

given by:

k is the effective length factor and is given in table 6-2 of the code.

Ncl, Rd

is the design axial local buckling resistance given by:

fclis the characteristic local buckling strength (as determined by Clause

6.3.3)

The reduction factors used in this clause depend on the ‘structural element type’and will be as given in Table 6-2 of N-004. This requires the member to beclassified under any one of the section types given in the table.

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Combined Bending and Shear (without Hydrostatic Pressure)

Clauses 6.3.8.3 & 6.3.8.4 state that tubular members subject to beam shear force(excluding shear due to torsion) and bending moments shall satisfy:

MSd/MRd≤ √(1.4 - V

Sd/VRd) when V

Sd/VRd≥ 0.4

MSd/MRd≤ 1.0 when V

Sd/VRd< 0.4

If the member is subject to shear forces due to torsion along with bendingmoments, the condition to be satisfied is:

MSd/MRed,Rd

≤ √(1.4 - VSd/VRd) when V

Sd/VRd≥ 0.4

MSd/MRed,Rd

≤ 1.0 when VSd/VRd< 0.4

Where:

MRed,Rd

= W fm,Red

/γm

fm,Red

= fm√[1 - 3(τ

T,Sd/fd)2]

τT,Sd

= MT,Sd

/(2π R2 t)

fd= f

y/γm

R = Radius of the tubular member

γm= Refer to clause 6.3.7

Combined Loads with Hydrostatic Pressure

Clause 6.3.9 of NS-004 describes two methods to check for members subject tocombined forces in the presence of hydrostatic pressure: depending on whetherthe hydrostatic forces were included as nodal forces in the analysis or not. If thehydrostatic forces have not been included in the analysis as nodal forces, Method Agiven in the code is used. If, however, the hydrostatic forces have been included inthe analysis, then Method B in the code is used. Prior to proceeding with the checksdescribed in the sections below, the section is verified for hoop stress limit perclause 6.3.6 (see Hydrostatic Pressure above).

The choice of method for checking members subject to combined forces andhydrostatic pressure used by STAAD.Pro will depend on the HYD parameterspecified as a design parameter. If the HYD parameter has been specified, then the

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program will assume that the hydrostatic forces have not been included in theanalysis and will perform the necessary checks as per Method A in code. If, on theother hand, the HYD parameter has not been specified, the program will use thesection forces and use Method B in the code.

Combined Axial Tension, Bending, and Hydrostatic Pressure

Checks per Clause 6.3.9.1:

A. When HYD is specified:

The following condition is to be satisfied:

a. For the net axial tension condition (σa,Sd

≥ σq,Sd

)

Where:

σa,Sd

is the design axial stress, excluding any axialcompression from hydrostatic pressure.

σq,Sd

is the design axial compressive stress due tohydrostatic pressure. (i.e., the axial load arising from thehydrostatic pressure being applied as nodal loads).

σmy,Sd

is the out of plane bending stress

σmz,Sd

is the in plane bending stress

fth,RD

= fy/γm[√(1 + 0.09 B2 - B2η) - 0.3B]

fmh,RD

= fm/γm[√(1 + 0.09 B2 - B2η) - 0.3B]

B = σpsd/ fh,Rd

η = 5 - 4 fh/fy

b. For the net axial compression condition (σa,Sd

< σq,Sd

)

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Where:

fcl,Rd

= fcl/γm

fclis the characteristic local buckling strength (as

determined by Clause 6.3.3)

Additionally, when:

σc,Sd

> 0.5 fhe/γm

and

fcle> 0.5 f

he

the following condition shall be satisfied in addition to the abovecheck(s):

Where:

σc,Sd

is the maximum compressive stress at that section.

B. When HYD has not been specified:

Where:

σac,Sd

is the axial stress in the member

Combined Axial Compression, Bending, and Hydrostatic Pressure

Checks per Clause 6.3.9.2:

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A. Method used when HYD has been specified:

The following condition is to be satisfied:

and

Where:

σa,Sd

is the design axial stress that excludes the stress fromhydrostatic pressure

Additionally, when:

σc,Sd

> 0.5 fhe/γm

and

fcle> 0.5 f

he

the following condition shall be satisfied in addition to the above check(s):

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B. Method used when HYD has not been specified:

The following condition is to be satisfied:

a. For the net axial tension condition (σac,Sd

≥ σq,Sd

)

and

(Refer to the previous section for an explanation of these terms).

b. For the net axial compression condition (σac,Sd

< σq,Sd

)

(Refer to the previous section for an explanation of these terms).

Additionally, when:

σc,Sd

> 0.5 fhe/γm

and

fcle/γm> 0.5 f

he/γm

the following condition shall be satisfied in addition to the abovecheck(s):

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Where:

σc,Sd

is the maximum compressive stress at that section.

19B.4 Design Parameters

Design parameters communicate specific design decisions to the program. Theyare set to default values to begin with and may be altered to suite the particularstructure.

ParameterName

DefaultValue

Description

CODE none Must be specified as NORSOK.

Note: Do not use the shortenedNOR, as this initiates an NS3472design.

FYLD 235 [MPa] Yield strength of steel, fy(St37)

Note: Note, if the SGR value isspecified, then the associatedvalue of f

yfor that steel grade will

be used for a member in lieu ofthe FYLD value.

KY 1.0 Effective length factor, k, in local Y-axis, usually minor axis.

KZ 1.0 Effective length factor, k, in local Z-axis, usually major axis.

LY MemberLength

Length in local Y axis for slendernessvalue KL/r

Table 19B.1 - Design Parameters for NORSOK N-004 design code

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ParameterName

DefaultValue

Description

LZ MemberLength

Length in local Z axis for slendernessvalue KL/r

CMY 0.85 Reduction factor Cmcorresponding

to the Y axis.

CMZ 0.85 Reduction factor Cmcorresponding

to the Z axis.

LSR Length of Tubular between StiffeningRings. This value is required to cal-culate Design Hoop Stress due toHydrostatic Pressure to check HoopBuckling as per clause 6.3.6.1.

HYD 0.0 The Y-coordinate, current units, ofthe maximum water level with respectto the origin.

Note: If SET Z UP command hasbeen specified, then yi will be theZ co-ordinate of the max waterlevel.

For HYD > 0, the value of max.hydrostatic pressure calculated isreported for each member in a TRACK2.0 output.

PSD 0.0 Water pressure at each section inabsence of HYD.

SGR 0.0 Steel Grade per EC3 (EN 1993-1-1:2005):

0.0 = S 235 grade steel

1.0 = S 275 grade steel

2.0 = S 355 grade steel

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ParameterName

DefaultValue

Description

3.0 = S 420 grade steel

4.0 = S 460 grade steel

DMAX 100.0 [cm] Maximum allowable depth of steel sec-tion.

DMIN 0.0 [cm] Minimum allowable depth of steel sec-tion.

DFF None (Man-datory for deflectioncheck)

"Deflection length"/maximum allow-able local deflection.

MAIN 0.0 Option to design for slenderness.

0.0 = Check forslenderness

1.0 = Do not check forslenderness

Any value greater than1.0 is used as the limit forslenderness incompression.

TMAIN 180.0 Slenderness limit in tension. Slen-derness limit is checked based theMAIN parameter.

TRACK 0.0 Output detail:

0.0 = Only a summary ofthe design checksperformed is printed.

2.0 = All the details of themember checks and thevarious clause checksperformed are printed.

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ParameterName

DefaultValue

Description

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

BEAM 0.0 Beam segment locations for design:

0.0  =  design only forend moments and thoseat locations specified bySECTION command.

1.0  =  Perform design formoments  at twelfthpoints along the beam.

DJ1 Start Jointof member

Joint No. denoting start point for cal-culation of “deflection length”

DJ2 End Jointof member

Joint No. denoting end point for cal-culation of “deflection length”

Notes

a. C1 and C2 Parameters

The default values of these coefficients are taken from Table 6-4 of N-004 anddepend on the joint and load type:

Joint Type C1 C2

T or Y joints under brace axial load 25 11

X joints under brace axial load 20 22

K joints under balanced axial load 20 22

All joints under brace moment load-ing

25 30

Table 19B.2 - Default values for C1 and C2parameters

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Note: These values can be changed by setting the K, X, and Y values inthe external geometry file.

Example

Note: This is a partial example containing only the information pertaining tothe NORSOK N-004 steel design code; used at the end of the input file.

* CHECK TUBULARMEMBERS ACCORDING NORSOK N-004

CODE NORSOK

HYD 3.0 MEMB 1 TO 3

PSD 10 MEMB 7 10

SGR 2 MEMB 1 TO 3 7 10

TRACK 2 MEMB 1 TO 3 7 10

CHECK CODEMEMB 1 TO 3 7 10

19B.5 Code Checking

The purpose of code checking is to ascertain whether the provided sectionproperties of the members are adequate as per N-004.  Code checking is doneusing the forces and moments at specific sections of the members.  If no sectionsare specified, the program uses the start and end forces for code checking.

When code checking is selected, the program calculates and prints whether themembers have passed or failed the checks, the critical condition of NORSOK code,the value of the ratio of the critical condition (overstressed for value more than 1.0or any other specified RATIO value), the governing load case, and the location(distance from the start of the number of forces in the member) where the criticalcondition occurs.

19B.6 Member Selection

STAAD is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section(i.e., the lightest section which fulfills the code requirements for the specifiedmember).  The section selected will be of the same type section as originally

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designated for the member being designed.  Member selection can also beconstrained by the parameters DMAX and DMIN which limit the maximum andminimum depth of the members.

Selection of members whose properties are originally input from a user createdtable will be limited to sections in the user table.

19B.7 Tubular Joint Checking

The design of tubular joints for this implementation shall be based on section 6.4 ofN-004 and will be applicable to joints formed from a connection of two or moremembers.

Figure - Typical Tubular Joint (Fig 6-1 in N004)

Prior to completing a joint design, the joint should be classified into one of thethree categories given by the code. Joint classification is the process whereby aBRACE member connecting into a CHORD member is classified into one of thesecategories based on the axial force components in the brace. The classificationnormally considers all the members at a joint that lie in a plane. N-004 definesthree joint classification categories: K, X, or Y (or a combination of these).

Joint Clas-sification

Description

K The axial force in the braceshould be balanced by forces inthe other braces in the same

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Joint Clas-sification

Description

plane and on the same side ofthe joint. The code allows a10% tolerance in the balancingforce.

X The axial force in the brace isreacted as a beam shear in thechord.

Y The axial force in the brace iscarried through the chord tobraces in the opposite side.

Note: Typical examples of these joint types are given in Figure 6-3 of the N-004 code. It is worth noting that the joint class for each brace will be differentfor each load case.

Note: STAAD.Pro does not perform an automatic classification of the joints.This is left up to the engineer. All joints will initially be classified as Y in thegeneration of the external geometry file. Joints should be re-classified asnecessary before performing the final joint capacity checks.

The checks for joint capacity are given in Cl. 6.4.3.2 to 6.4.3.6 and STAAD.Properforms the checks as per these clauses. However, the program does not dealwith conical joint transitions and joints with joint cans. The code also specifieschecks and limits for the gaps and eccentricity of joints. This implementation willnot perform such geometry checks.

The details of the checks done and the methodology will be discussed in thefollowing sections.

Identification and Classification of CHORD and BRACE Members

This is a two step process where the program automatically identifies the CHORDand BRACE members at a joint and perform a default joint check. The inputvariables used for the initial joint checks will be generated in an external text file.

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You can then use this text file to edit or modify the input variables and perform afinal check as necessary.

The following syntax is used to initiate the joint checking in the engine.

LOAD LIST load_list

PARAMETER 1

CHECK JOINT { node_list | ALL }

Where:

load_list = a list of load case numbers to be check against

node_list = the NODE numbers to be checked. Specifying the ALLkeyword option will cause the program to perform the joint check at allthe nodes.

For each node specified in the CHECK JOINT command, the program automaticallyseparates out all the members at the node into one CHORD member and one ormore BRACE members. The section with the biggest diameter is assumed to be theCHORD and all the other members are assumed as BRACE members. If two or morepossible CHORD members have the same diameter, the member with the maximumthickness is considered as the CHORD. The angle between the two members shouldbe within the range of 30° and 90° (inclusive).

Once all the CHORD and BRACE members are identified, the program considersevery CHORD to BRACE connection as a separate JOINT. The program theautomatically creates the joints and initially considers all the joints as joint class Y.The program then performs all the necessary joint checks as detailed in thefollowing sections and produces the design output. The program will also producean output file called FILENAME_ JOINTS.TXT, where "filename" will be the name ofthe .STD file. This format of this text file is explained in Section 19B.8.

You can then edit this text file to set up the necessary design parameters. Once theprogram finds of the _JOINTS.TXT file, it will read in the necessary parametersfrom this file and perform the subsequent design checks.

Note: This file will be produced only once (i.e., when this file does not exist). Ifthis file exists, it is assumed that you have already done a joint design check andhence the program reads the values from this file and uses these for jointchecks.

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19B.7 Tubular Joint Resistance

Basic Joint Resistances

The characteristic joint resistance between a chord and a brace is given by:

Where:

NRdis the joint design axial resistance

MRdis the joint design bending moment resistance.

fyis the yield strength

γm= Default material resistance =1.15

θ is the angle between the chord and the brace (max θ = 90 degrees)

Qu= Strength factor which varies with the joint type and the action

type in the brace. Refer to Table 6-3 and Clause 6.4.3.3 of N-004 forthese equations.

Qf= 1.0 – λA2

σp,Sd

is the design axial stress in the chord

σmy,Sd

is the design in-plane bending stress in the chord

σmz,Sd

is the design out-of-plane bending stress in the chord

C1 is the coefficient used for the axial stress term in calculating thejoint resistance. C2 is the coefficient used for the bending stress termin calculating the joint resistance. The default values of C1 and C2 areas given in Table 6-4 of N-004. The actual values used are dependent

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on the values of K, X, and Y specified for the joint in the externalgeometry file.

See also Figures 6-3 to 6-6 of N-004 for definition of the various termsfor various joint classes.

Strength Check for Joints

Each brace to chord joint to be checked will have to satisfy the following condition:

Where:

NSdis the design axial force in the brace,

NRdis the joint design axial resistance

Mz,Sd

is the in plane bending moment in the brace

My,Sd

is the out of plane bending moment in the brace

Mz,Rd

is the in plane bending moment resistance

My,Rd

is the out of plane bending moment resistance

19B.7 External Geometry File

The data contained in the FILENAME_JOINTS.NGO file should meet the followingformat. The overall process of performing punching shear checks consists of twosteps which are explained in section 19B.7.

General Format

LOAD LIST load_list

JOINT NODE K X Y CHORD CLEN D T BRACE BLEN d t GAP

j# n# K% X% Y% C# CLEN D T B# BLEN d t gap

Where:

j# = the joint number

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n# = the node number

K%, X%, and Y% = The fractional contributions of K-type, X type andY-type, respectively. Initially the joints will be classed as Y (i.e., K=0,X=0 and Y=1).

C# = the member numbers of the CHORD

CLEN = the length of chord member

D, T = Diameter and thickness of CHORD

B# = the member number of the brace

BLEN = the length of chord member

d, t = Diameter and thickness of BRACE

gap = Distance required to calculate gap factor for K bracing. Initially,the value of GAP is assumed as 0.

Example

LOAD LIST 1 2 4JOINT NODE K X Y CHORD CLEN D T BRACEBLEN D T GAP1 3 0 0 1 2 5.0 0.168 0.10 1 4.0

0.140 0.010 02 3 0 0 1 2 5.0 0.168 0.10 16 6.043

0.075 0.005 0

19B.5 Tabulated Results

For code checking or member selection, the program produces the results in atabulated fashion.  The items in the output table are explained as follows:

a. Member refers to the member number for which the design is performed.

b. TABLE refers to the steel section name which has been checked against theN-004 code or has been selected.

c. RESULTS prints whether the member has PASSed or FAILed.  If the RESULTis FAIL, there will be an asterisk (*) mark on front of the member.

d. CRITICAL COND refers to the section of the N-004 code which governs the

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design.

e. RATIO prints the ratio of the actual stresses to allowable stresses for thecritical condition.  Normally a value of 1.0 or less will mean the member haspassed.

f. LOADING provides the load case number which governed the design.

g. FX, MY, and MZ provide the axial force, moment in local Y-axis, and themoment in local Z-axis respectively.  Although STAAD does consider all themember forces and moments (except torsion) to perform design, only FX, MYand MZ are printed since they are the ones which are of interest, in mostcases.

h. LOCATION specifies the actual distance from the start of the member to thesection where design forces govern.

i. If the parameter TRACK is set to 2.0, the program will block out part of thetable and will print the allowable bending stressed in compression (FCY &FCZ) and tension (FTY & FTZ), allowable axial stress in compression (FA), andallowable shear stress (FV).

Sample TRACK 2.0 Output

STAAD.PRO CODE CHECKING - NORSOK-N004 (V1.0)************************************************

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/FX MY MZ LOCATION

=======================================================================1 ST PIP13910.0 (BRITISH SECTIONS)

PASS Eq. 6.44 0.170 10.01 C 1.01 6.39 0.00

=======================================================================MATERIAL DATA

Grade of steel = S 355Modulus of elasticity = 204999.98 N/mm2Design Strength (py) =355.00 N/mm2

SECTION PROPERTIES (units - cm)Member Length = 400.00Gross Area of cross section = 40.70

z-axis y-axisMoment of inertia : 862.000 862.000Plastic modulus : 168.554 168.554

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Elastic modulus : 123.407 123.407Radius of gyration : 4.602 4.602Effective Length : 400.000 400.000

DESIGN PARAMETER (units - m) N004/2004Height of water lavel : 3.000CMZ : 0.85 CMY : 0.85KZ : 1.00 KY : 1.00

SECTION CLASSIFICATION : Class 1

CAPACITIES (units - kN,m)Tension Capacity : 1256.4Compression Capacity : 790.1Bending Capacity : 52.0Shear Capacity : 362.7Shear Capacity due to torsional moment: 44.0

HYDROSTATIC PRESSURE CALCULATION (units - N,mm) - Cl.6.3.6Max design hydrostatic pressure, (psd) : 0.000Max design hoop stress, (sigma_psd)) : 0.000

CRITICAL LOAD FOR EACH CLAUSE CHECK (units - kN,m):CLAUSE RATIO LOAD FX VY VZ MZ MYCl:6.3.2 0.000 1 0.0 - - - -Cl:6.3.3 0.000 1 0.0 - - - -Cl:6.3.4 0.102 1 - - - -5.3 0.0Cl:6.3.5 0.031 1 - -11.2 0.5 - -Cl:6.3.8.(1 & 2) 0.124 1 0.0 - - 6.4 1.0Cl:6.3.8.(3 & 4) 0.102 1 - -0.5 0.5 -5.3 0.0Cl:6.3.9 0.170 1 0.0 - - 6.4 1.0

=======================================================================

Norwegian Codes - Concrete Design per NS3473

19C.1 - General Notes

This section presents a description of the parameters used by STAAD.Pro forperforming code checks members according to Norwegian Standard NS 3473"Concrete Structures - Design and detailing rules" (hereafter referred to as NS3473).

19C.2 Design Parameters

Design parameters communicate specific design decisions to the program. Theyare set to default values to begin with and may be altered to suite the particular

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structure.

ParameterName

DefaultValue

Description

CODE none Must be specified as NS3473

Design Code to follow.

See section 5.52.2 of the TechnicalReference Manual.

ACTAGE 70years

Enter the actual age, in years.

BRACE 0 Column Brace Parameter

0. Beam/ Column braced in both direc-tions.

1. One-way plate/ Column unbracedabout the local z axis only.

2. Column unbraced about the local yaxis only.

3. Column unbraced in both direc-tions.

CLEAR 25 mm Clear cover to outermost reinforcing bar.

DRYCIR 100% Drying exposure, in percent.

EFACE 0 Distance from the end node of the beamto face of support for shear design.

ELY 1 Member length factor about the local ydirection.

ELZ 1 Member length factor about the local zdirection

ENVIR 2 Environment class

1. LA — Least aggressive

2. NA — Aggressive

Table 19B.3 - Design Parameters for NS 3473 design code

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ParameterName

DefaultValue

Description

3. MA — Very aggressive

FC 35N/mm2

Compressive strength of concrete.

FYMAIN 500N/mm2

Yield strength of main reinforcing steel.

LAGE 7 days Age when loaded, in days.

MAXMAIN 32 Maximum size permitted for main rein-forcement bar.

MINMAIN 10 Minimum size permitted for main rein-forcement bar.

MOY moy factor

MOZ moz factor

NMAG nmag factor

REIANG 0 Reinforcement angle, in degrees.

RELHUM 70% Relative humidity, in percent.

RFACE 1 Column bar arrangement

1. Four longitudinal bars.

2. Two faced distribution about minoraxis.

3. Two faced distribution about majoraxis.

4. Faced symmetric distribution

SFACE 0 Distance from the start node of the beamto face of support for shear design.

STIRANG 90 Stirrup angle, in degrees.

STIRDIA 10 mm Stirrup diameter

TORANG 45 Torsion angle, in degrees.

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ParameterName

DefaultValue

Description

TRACK 10 Track parameter to control output detail

10. Beam— Ultimate limit state andService limit state design & Slab —Two-way plate design

11. Beam— Ultimate limit state andService limit state design with ten-sion stiffening.

12. Beam— Ultimate limit state designonly

20. Slab — Plane stress design.

30. Slab — Simplified membranedesign.

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Section 20

Cypriot Codes

Cypriot Codes - Concrete Design in Cyprus

20.1 Design ParametersThe program contains a number of parameters which are needed to perform andcontrol the design to the concrete code of Cyprus. These parameters not only act asa method to input required data for code calculations but give the Engineer controlover the actual design process. Default values of commonly used parameters forconventional design practice have been chosen as the basis. Table 20A.1 contains acomplete list of available parameters with their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CODE - Must be specified as CYPRUS.

Design Code to follow. See section5.52.2 of the Technical ReferenceManual.

BRACE 0.0 Bracing parameter for column design:

0. Column braced in both directions

1. Column braced in only the local Ydirection.

2. Column braced in only the local Zdirection.

3. Column unbraced in either direc-tion.

CLEAR 20 mm Clearance of reinforcement measuredfrom concrete surface to closest barperimeter, in current units.

DEPTH YD Depth of concrete member, in currentunits. This value default is as providedas YD in MEMBER PROPERTIES.

EFACE 0.0 Face of support location at end ofbeam, in current units.

Note: Both SFACE & EFACE mustbe positive numbers.

ELY 1.0 Member length factor about local Ydirection for column design.

ELZ 1.0 Member length factor about local Zdirection for column design.

FC 4.0 ksi Concrete Yield Stress / cube strength,in current units

Table 20C.1 - Cypriot Concrete Design Parameters

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ParameterName

DefaultValue

Description

FYMAIN 60 ksi Yield Stress for main reinforcement, incurrent units (For slabs, it is forreinforcement in both directions)

FYSEC 60 ksi Yield Stress for secondaryreinforcement a, in current units.Applicable to shear bars in beams.

MAXMAIN 50 mm Maximum required reinforcement barsize Acceptable bars are per MINMAINabove.

MINMAIN 8 mm Minimummain reinforcement bar sizeAcceptable bar sizes: 6 8 10 12 16 2025 32 40 50

MINSEC 8 mm Minimum secondary bar size a.Applicable to shear reinforcement inbeams

MMAG 1.0 Factor by which column designmoments are magnified

NSECTION 12 Number of equally-spaced sections tobe considered in finding criticalmoment for beam design. The upperlimit is 23.

SERV 0.0 Serviceability checks:

0. No serviceability check per-formed.

1. Perform serviceability check forbeams as if they were con-tinuous.

2. Perform serviceability check forbeams as if they were simply sup-ported.

3. Perform serviceability check forbeams as if they were cantilever

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ParameterName

DefaultValue

Description

beams.

SFACE 0.0 Face of support location at start ofbeam, in current units. (Onlyapplicable for shear - use MEMBEROFFSET for bending )

SRA 0.0 Skew angle considered in Wood &Armer equations where A is the anglein degrees.

Two special values are alsoconsidered:

0.0 = Orthogonalreinforcement layoutwithout consideringtorsional moment Mxy -slabs only

-500 = Orthogonalreinforcement layout withMxy used to calculate Wood& Armer moments fordesign.

TRACK 0.0 Controls level of detail in output:

0. Critical Moment will not beprinted with beam design report.Column design gives no detailedresults.

1. For beam gives min/max steel %and spacing. For columns gives adetailed table of output with addi-tional moments calculated.

2. Beam design only. Details of rein-forcement at sections defined bythe NSECTION parameter.

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ParameterName

DefaultValue

Description

WIDTH ZD Width of concrete member, in currentunits. This value default is as providedas ZD in MEMBER PROPERTIES.

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Section 21

Danish Codes

Danish Codes - Steel Design per DS412

21.1 Design ParametersThe design parameters outlined in Table 21.1 may be used to control the designprocedure. These parameters communicate design decisions from the engineer tothe program and thus allow you to control the design process to suit anapplication's specific needs.

The default parameter values have been selected such that they are frequently usednumbers for conventional design. Depending on the particular designrequirements, some or all of these parameter values may be changed to exactlymodel the physical structure.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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Parameter Name Default Value Description

CODE - Must be specifiedas DS412

Design Code tofollow.

See section5.48.1 of theTechnicalReferenceManual.

BEAM 1.0 1.0  = Calculate vonMises at twelfthpoints along thebeam.

BY 1.0 Buckling lengthcoefficient, Beta,about the local Yaxis.

BZ 1.0 Buckling lengthcoefficient, Beta,about the local Zaxis.

CB 1.0 Lateral bucklingcoefficient. Usedto calculate theideal bucklingmoment.

CMY 1.0 Water depth, inmeters, forhydrostatic pres-sure calculationfor pipemembers.

Table 21D.1 - Danish Steel Design DS412 Parameters

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Parameter Name Default Value Description

CMZ 0.21 AlphaT in con-nection with lat-eral buckling.

CY Buckling curvecoefficient,Alpha, aboutlocal Y-axis.

CZ Buckling curvecoefficient,Alpha, aboutlocal Z-axis.

DMAX 1,000 mm Maximumallowable depth(Applicable formemberselection)

DMIN 0.0 mm Minimumrequired depth(Applicable formemberselection)

FYLD 235 N/mm2 Yield strength ofsteel.

MF 1.15 Ratio of materialfactor to resist-ance factor.

RATIO 1.0 Permissible ratioof actual loadeffect to thedesign strength.

SSY Equivalentmoment factor,BetaM, for localY-axis. Valid

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Parameter Name Default Value Description

values between0 and 2.5.

SSZ Equivalentmoment factor,BetaM, for localZ-axis. Validvalues between0 and 2.5.

TRACK 0.0 Used to specify alevel of detail inoutput:

0. Reportonly mini-mumdesignresults.

1. Reportdesignstrengthsalso.

2. Provide fulldetails ofdesign.

UNL Member Length Unsupportedlength inbendingcompression ofthe bottomflange forcalculatingmomentresistance.

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Section 22

Dutch Codes

Dutch Codes - Steel Design per NEN 6770

22.1 Design ParametersAvailable design parameters to be used in conjunction with NEN 6770 are listed intable 22.1 along with their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

ParameterName

Default Value Description

CODE - Must be specified as DUTCH

Design Code to follow.

Table 22E.1 - Dutch Steel Design NEN 6770 Parameters

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ParameterName

Default Value Description

See section 5.48.1 of theTechnical Reference Manual.

BEAM 3.0 Used to specify the number ofsections to be check along thelength of the beam:

0. Check sections with endforces only.

1. Check at location of max-imum Mz along beam.

2. Check sections with endforces and forces at loca-tion of BEAM = 1.0 check.

3. Check at every 1/13thpoint of the beam andreport the maximum.

CMM 1.0 Loading type per Tables F.1.1and F.1.2

1. Pin ended member with uni-form loading

2. Fix ended member with uni-form loading

3. Pin ended member withcentral point load.

4. Fix ended member with cen-tral point load.

5. Pin ended member withpoint loads at third points.

6. Pin ended member with var-ying end moments.

CMN 1.0 Used to describe the endrestraints:

1.0 = No fixity

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ParameterName

Default Value Description

0.7 = One end fixed,the other free.

0.5 = Both endsfixed.

DFF None(Mandatory fordeflection check,TRACK 4.0)

"Deflection Length" / Maximumallowable local deflection

See Note 1d in Section 2B.6.

DJ1 Start Jointof member

Joint No. denoting starting pointfor calculation of "DeflectionLength" . See Note 1 below.

DJ2 End Joint ofmember

Joint No. denoting end point forcalculation of "DeflectionLength". See Note 1 below.

DMAX 10,000 cm Maximum allowable depthDMIN 0.0 cm Minimum allowable depthKY 1.0 K factor value in local y - axis.

Usually, this is the minor axis.KZ 1.0 K factor value in local z - axis.

Usually, this is the major axis.LY Member Length Length in local y - axis (current

units) to calculate (KY)(LY)/Ryyslenderness ratio.

LZ Member Length Length in local z - axis (currentunits) to calculate (KZ)(LZ)/Rzzslenderness ratio.

NSF 1.0 Net section factor for tensionmembers.

PY Set according tosteel grade (SGR)

Design strength of steel

RATIO 1.0 Permissible ratio of the actualcapacities.

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ParameterName

Default Value Description

SAME 0.0 Controls the sections to tryduring a SELECT process.

0. Try every section of thesame type as original

1. Try only those sectionswith a similar name as orig-inal (e.g., if the original isan HEA 100, then only HEAsections will be selected,even if there are HEM’s inthe same table).

SBLT 0.0 Identify Section type for sectionclassification

0. Rolled Section

1. Built up SectionSGR 0.0 Steel Grade

0. Grade Fe 360

1. Grade Fe 430

2. Grade Fe 510TRACK 0.0 Used to control the level output

detail:

0. Output summary of results.

1. Output summary of resultswith member capacities.

2. Output detailed results.

3. Deflection Check (separatecheck to main select /check code)

UNL Member Length Unrestrained member length inlateral torsional buckling checks.

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Section 23

Finnish Codes

Finnish Codes - Concrete Design per B4

23A.1 Design ParametersThe program contains a number of parameters which are needed to perform andcontrol the design to the B4 code. These parameters not only act as a method toinput required data for code calculations but give the Engineer control over theactual design process. Default values of commonly used parameters forconventional design practice have been chosen as the basis. Table 26B.1 contains acomplete list of available parameters with their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CODE - Must be specified as FINNISH.

Design Code to follow. See section5.52.2 of the Technical ReferenceManual.

ACTAGE 70 Actual age of concrete, in years.

BRACE 0.0 Bracing parameter for design:

0. Beam or column braced in bothdirections

1. One-way plate or column bracedin only the local Z direction.

2. Column braced in only the localY direction.

3. Column unbraced in either direc-tion.

CLEAR 25 mm Clearance of reinforcement measuredfrom concrete surface to closest barperimeter, in current units.

DRYCIR 100 Drying exposure, in percent.

EFACE 0.0 Face of support location at end ofbeam, in current units.

Note: Both SFACE & EFACE mustbe positive numbers.

ELY 1.0 Member length factor about local Ydirection for column design.

ELZ 1.0 Member length factor about local Zdirection for column design.

Table 23F.1 - Finnish Concrete Design per B4 Parameters

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ParameterName

DefaultValue

Description

ENVIR 2 Environment class

1. LA — Least aggressive

2. NA — Aggressive

3. MA — Very aggressive

FC 35N/mm2

Compressive strength of concrete.

FYMAIN 500N/mm2

Yield strength of main reinforcingsteel.

LAGE 7 days Age when loaded, in days.

MAXMAIN 32 Maximum size permitted for main rein-forcement bar.

MINMAIN 10 Minimum size permitted for main rein-forcement bar.

MOY moy factor

MOZ moz factor

NMAG nmag factor

REIANG 0 Reinforcement angle, in degrees.

RELHUM 40 Relative humidity, in percent.

RFACE 1 Column bar arrangement

1. Four longitudinal bars.

2. Two faced distribution aboutminor axis.

3. Two faced distribution aboutmajor axis.

4. Faced symmetric distribution

SFACE 0 Distance from the start node of thebeam to face of support for sheardesign.

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ParameterName

DefaultValue

Description

Note: Both SFACE & EFACE mustbe positive numbers.

STIRANG 90 Stirrup angle, in degrees.

STIRDIA 10 mm Stirrup diameter

TORANG 45 Torsion angle, in degrees.

TRACK 10 Track parameter to control outputdetail

10. Beam— Ultimate limit state andService limit state design & Slab— Two-way plate design

11. Beam— Ultimate limit state andService limit state design withtension stiffening.

12. Beam— Ultimate limitstate design only

20. Slab — Plane stress design.

30. Slab — Simplified membranedesign.

Finnish Codes - Steel Design per B7

23B.1 Design ParametersDesign parameters communicate specific design decisions to the program. Theyare set to default values to begin with and may be altered to suite the particularstructure.

ParameterName

DefaultValue

Description

CODE none Must be specified as either NS3472 for

Table 23F.2 - Design Parameters for Norwegian Steel design code

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ParameterName

DefaultValue

Description

NS or NPD for NPD (NOR may also beused for both).

Design Code to follow.

See section 5.48.1 of the TechnicalReference Manual.

BEAM 0.0 Parameter BEAM 1.0 ALL tells theprogram to calculate von Mises at 13sections along each member, and up to8 points at each section. (Dependingon what kind of shape is used.)

Note: Must be set to 1.0

BY 1.0 Buckling length coefficient, β for weakaxis buckling (y-y) (NOTE: BY > 0.0)

BZ 1.0 Buckling length coefficient, β, forstrong axis buckling (z-z) (NOTE: BZ >0.0)

CB 1.0 Lateral buckling coefficient, Y. Used tocalculate the ideal buckling moments,Mvi

CMY 1.0 Water depth in meters for hydrostaticpressure calculation for pipe members

CMZ 0.49 αLTfor sections in connection with lat-

eral buckling

CY

CZ

Defaultsee NS3472

Buckling curve coefficient, a aboutlocal z-axis (strong axis). Representthe a, a0, b, c, d curve.

DMAX 100.0[cm]

Maximum allowable depth of steel sec-tion.

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ParameterName

DefaultValue

Description

DMIN 0.0 [cm] Minimum allowable depth of steel sec-tion.

FYLD 235 Yield strength of steel, fy (St37)[N/mm2 ]

MF 1.1(NS3472)1.15(NPD)

Material factor / Resistance factor, γm

RATIO 1.0 Permissible ratio of the actual to allow-able stresses.

SSY 0.0 0.0 = No sidesway. β calculated. > 0.0= Sidesway in local y-axis weak axisβM=SSY

SSZ 0.0 0.0 = No sidesway. β calculated. > 0.0= Sidesway in local y-axis weak axisβM

TRACK 0.0 0.0 = Supress critical member stresses.1.0 = Print all critical memberstresses, i.e., DESIGN VALUES 2.0 =Print von Mises stresses. 9.0 = Largeoutput, 1 page for each member. Seesection 7 and Appendix A for completelist of available TRACKs and print exam-ples.

UNL Memberlength

Effective length for lateral buckling cal-culations (specify buckling length). Dis-tance between fork supports orbetween effective side supports for thebeam

The parameter CMY will, when given with negative value, define an inside pressurein pipe members. The pressure corresponds to given water depth in meters.

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The parameter CB defines the φ value with respect to calculation of the ideal lateralbuckling moment for single symmetric wide flange profiles, ref. NS app. 5.2.2.

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Section 24

Singaporian Codes

Singaporean Codes - Concrete Design per CP65

24.1 Design ParametersThe program contains a number of parameters which are needed to perform andcontrol the design per the CP65 code. These parameters not only act as a methodto input required data for code calculations but give the Engineer control over theactual design process. Default values of commonly used parameters forconventional design practice have been chosen as the basis. Table 24.1 contains acomplete list of available parameters with their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

International Design Codes Manual — 1035

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ParameterName

DefaultValue

Description

CODE - Must be specified as CP65.

Design Code to follow. See section5.52.2 of the Technical ReferenceManual.

BRACE 0.0 Bracing parameter for column design:

0. Column braced in both directions

1. Column braced in only the local Ydirection.

2. Column braced in only the local Zdirection.

3. Column unbraced in either direc-tion.

CLEAR 20 mm Clearance of reinforcement measuredfrom concrete surface to closest barperimeter, in current units.

DEPTH YD Depth of concrete member, in currentunits. This value default is as providedas YD in MEMBER PROPERTIES.

EFACE 0.0 Face of support location at end ofbeam, in current units.

Note: Both SFACE & EFACE mustbe positive numbers.

ELY 1.0 Member length factor about local Ydirection for column design.

ELZ 1.0 Member length factor about local Zdirection for column design.

FC 4.0 ksi Concrete Yield Stress / cube strength,in current units

Table 24G.1 - Singaporean Concrete Design CP65 Parameters

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ParameterName

DefaultValue

Description

FYMAIN 60 ksi Yield Stress for main reinforcement, incurrent units (For slabs, it is forreinforcement in both directions)

FYSEC 60 ksi Yield Stress for secondaryreinforcement a, in current units.Applicable to shear bars in beams.

MAXMAIN 50 mm Maximum required reinforcement barsize Acceptable bars are per MINMAINabove.

MINMAIN 8 mm Minimummain reinforcement bar sizeAcceptable bar sizes: 6 8 10 12 16 2025 32 40 50

MINSEC 8 mm Minimum secondary bar size a.Applicable to shear reinforcement inbeams

MMAG 1.0 Factor by which column designmoments are magnified

NSECTION 12 Number of equally-spaced sections tobe considered in finding criticalmoment for beam design. The upperlimit is 23.

SERV 0.0 Serviceability checks:

0. No serviceability check per-formed.

1. Perform serviceability check forbeams as if they were con-tinuous.

2. Perform serviceability check forbeams as if they were simply sup-ported.

3. Perform serviceability check forbeams as if they were cantilever

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ParameterName

DefaultValue

Description

beams.

SFACE 0.0 Face of support location at start ofbeam, in current units. (Onlyapplicable for shear - use MEMBEROFFSET for bending )

SRA 0.0 Skew angle considered in Wood &Armer equations where A is the anglein degrees.

Two special values are alsoconsidered:

0.0 = Orthogonalreinforcement layoutwithout consideringtorsional moment Mxy -slabs only

-500 = Orthogonalreinforcement layout withMxy used to calculate Wood& Armer moments fordesign.

TRACK 0.0 Controls level of detail in output:

0. Critical Moment will not beprinted with beam design report.Column design gives no detailedresults.

1. For beam gives min/max steel %and spacing. For columns gives adetailed table of output with addi-tional moments calculated.

2. Beam design only. Details of rein-forcement at sections defined bythe NSECTION parameter.

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ParameterName

DefaultValue

Description

WIDTH ZD Width of concrete member, in currentunits. This value default is as providedas ZD in MEMBER PROPERTIES.

International Design Codes Manual — 1039

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Section 25

Spanish Codes

Spanish Codes - Concrete Design per EHE

25B.1 Design ParametersThe program contains a number of parameters which are needed to perform designper the Española del Hormigón Estructural (EHE) code. These parameters not onlyact as a method to input required data for code calculations but give the engineercontrol over the actual design process. Default values, which are commonly usednumbers in conventional design practice, have been used for simplicity. Table25A.1 contains a list of available parameters and their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CLB 1.5 in Clear cover to reinforcing bar at bottomof cross section.

CLS 1.5 in Clear cover to reinforcing bar along theside of the cross section.

CLT 1.5 in Clear cover to reinforcing bar at top ofcross section.

DEPTH YD Depth of the concrete member. Thisvalue defaults to YD as provided underMEMBER PROPERTIES.

EFACE 0.0Face ofSupport

Distance of face of support from endnode of beam. Used for shear andtorsion calculation.

Note: Both SFACE & EFACE must bepositive numbers.

FC 4.0 ksi Specified compressive strength ofconcrete.

FYMAIN 60 ksi Yield Stress for main reinforcing steel.

FYSEC 60 ksi Yield Stress for secondary reinforcingsteel.

MAXMAIN Number55 bar

Maximummain reinforcement bar size.

MINMAIN Number10 bar

Minimummain reinforcement bar size

MINSEC Number10 bar

Minimum secondary (stirrup)reinforcement bar size.

MMAG 1.0 A factor by which the column designmoments will be magnified.

NSECTION 12 Number of equally-spaced sections to be

Table 25H.1 - Spanish Concrete Design per EHE Parameters

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ParameterName

DefaultValue

Description

considered in finding critical momentsfor beam design.

REINF 0.0 Used to specify type of column shearreinforcement:

0. Tied Column.

1. Spiral Column.

SFACE 0.0 Distance of face of support from startnode of beam. Used for shear andtorsion calculation.

Note: Both SFACE & EFACE must bepositive numbers.

TRACK 0.0 Used to specify detail of output:

0. Only minimum details are printedfor beam or column designs.

1. Beam Design: Intermediate level ofdetail.

Column Design: TRACK 0 outputplus intermediate level of detail.

2. Beam Design: TRACK 1 detail plussteel required at 1/12th secitons.

Column Design: detailed output.

WIDTH ZD Width of the concrete member. Thisvalue defaults to ZD as provided underMEMBER PROPERTIES.

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Section 26

Swedish Codes

Swedish Codes - Concrete Design per BBK 94

26B.1 Design ParametersThe program contains a number of parameters which are needed to perform andcontrol the design to the BBK 94 code. These parameters not only act as a methodto input required data for code calculations but give the Engineer control over theactual design process. Default values of commonly used parameters forconventional design practice have been chosen as the basis. Table 26B.1 contains acomplete list of available parameters with their default values.

Note: Once a parameter is specified, its value stays at that specified number tillit is specified again. This is the way STAAD works for all codes.

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ParameterName

DefaultValue

Description

CODE - Must be specified as SWEDISH.

Design Code to follow. See section5.52.2 of the Technical ReferenceManual.

ACTAGE 70 Actual age of concrete, in years.

BRACE 0.0 Bracing parameter for design:

0. Beam or column braced in bothdirections

1. One-way plate or column bracedin only the local Z direction.

2. Column braced in only the localY direction.

3. Column unbraced in either direc-tion.

CLEAR 25 mm Clearance of reinforcement measuredfrom concrete surface to closest barperimeter, in current units.

DRYCIR 100 Drying exposure, in percent.

EFACE 0.0 Face of support location at end ofbeam, in current units.

Note: Both SFACE & EFACE mustbe positive numbers.

ELY 1.0 Member length factor about local Ydirection for column design.

ELZ 1.0 Member length factor about local Zdirection for column design.

Table 26I.1 - Swedish Concrete Design per BBK 94 Parameters

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ParameterName

DefaultValue

Description

ENVIR 2 Environment class

1. LA — Least aggressive

2. NA — Aggressive

3. MA — Very aggressive

FC 35N/mm2

Compressive strength of concrete.

FYMAIN 500N/mm2

Yield strength of main reinforcingsteel.

LAGE 7 days Age when loaded, in days.

MAXMAIN 32 Maximum size permitted for main rein-forcement bar.

MINMAIN 10 Minimum size permitted for main rein-forcement bar.

MOY moy factor

MOZ moz factor

NMAG nmag factor

REIANG 0 Reinforcement angle, in degrees.

RELHUM 40 Relative humidity, in percent.

RFACE 1 Column bar arrangement

1. Four longitudinal bars.

2. Two faced distribution aboutminor axis.

3. Two faced distribution aboutmajor axis.

4. Faced symmetric distribution

SFACE 0 Distance from the start node of thebeam to face of support for sheardesign.

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ParameterName

DefaultValue

Description

Note: Both SFACE & EFACE mustbe positive numbers.

STIRANG 90 Stirrup angle, in degrees.

STIRDIA 10 mm Stirrup diameter

TORANG 45 Torsion angle, in degrees.

TRACK 10 Track parameter to control outputdetail

10. Beam— Ultimate limit state andService limit state design & Slab— Two-way plate design

11. Beam— Ultimate limit state andService limit state design withtension stiffening.

12. Beam— Ultimate limitstate design only

20. Slab — Plane stress design.

30. Slab — Simplified membranedesign.

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Technical SupportThese resources are provided to help you answer support questions:

l Service Ticket Manager — http://www.bentley.com/serviceticketmanager —Create and track a service ticket using Bentley Systems' online site for report-ing problems or suggesting new features. You do not need to be a BentleySELECT member to use Service Ticket Manager, however you do need to reg-ister as a user.

l Knowledge Base — http://appsnet.bentley.com/kbase/ — Search the BentleySystems knowledge base for solutions for common problems.

l FAQs and TechNotes — http://-communities.bentley.com/Products/Structural/Structural_Analysis___Design/w/Structural_Analysis_and_Design__Wiki/structural-product-tech-notes-and-faqs.aspx — Here you can find detailed resolutions and answers tothe most common questions posted to us by you.

l Ask Your Peers — http://-communities.bentley.com/forums/5932/ShowForum.aspx — Post questionsin the Be Community forums to receive help and advice from fellow users.

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IndexA

AIJ 1991 See Concrete Design,AIJ 1991

AIJ 2002 See Steel Design, AIJ2002

AIJ 2005 See Steel Design, AIJ2005

AISC 97

Alclad 776

Aluminum Design 773

American Transmission Tower Code795,801,803

Analysis

PDelta 14

ANSI/AISC N690 Codes 823

AS 1170 21

AS 3600 9

AS 3600 - 2001 See ConcreteDesign, AS 3600

AS 4100 - 1998 See Steel Design,AS 4100

ASCE 10 795

ASCE 10-97 See Steel Design,ASCE 10-97

ASCE Manuals 801, 803

ASME NF Codes 869

Australian Codes 7, 9

Axial Compression 266, 795

Axial Tension 266, 795

Clause 3.13 795

stress 266

Axially Loaded Members 288, 305,307, 309

Design 288, 305, 307, 309

B

British

Codes 57

National Annex See NationalAnnex, British

British Codes 81-82, 108

BS 5950-5 See Steel Design, BS5950-5

BS EN 1993-1-1 337

BS4360 96

BS5400 See Steel Design,BS5400

BS5950 See Steel Design,BS5950

BS8007 See Steel Design,BS8007

BS8110 See Concrete Design,BS8110

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Index: CAN/CSA-086-01 – Egyptian Codes

C

CAN/CSA-086-01 See WoodDesign,

CAN/CSA-086-01

Canadian Codes 153

Canadian Wood Design Manual227

Changing 266

Chinese Codes 247, 261, 266-267

Cold Formed Steel

IS801 593

Combined Loading 267

stress 266

Concrete Design

AIJ 1991 603

AS 3600 9

BBK 94 1045

BS8110 59, 62

CP65 1035

CSA A23.3 155

DIN 1045 473

Egyptian Code 433

Eurocode EC2 275

GB50010 249

IS13920 521

IS456 495

NTC 1987 651

SABS-0100-1 739

CSA 156, 160

CSA A23.3 See ConcreteDesign, CSA A23.3

CSA CAN/CSA-S16-01 See SteelDesign, CSACAN/CSA-S16-01

D

DD ENV 284

DD ENV 1993 283, 288

Design 288, 305, 307, 309,323

Axially Loaded Members 288,305,307,309

Design Rules 459

Structural Steelwork 459

Dutch

National Annex See NationalAnnex, Dutch

E

EC5 405

ECCS205 433

Egyptian

Section 2.6.3 444

Egyptian Codes 431

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EN 1993 301

Equivalent slenderness 89

Eurocode 283, 288, 303, 305,307, 309, 323

Steel Design 288, 301, 305,307, 309, 323

European Codes 273, 275, 303,305, 307, 309,

323

Extrusions 781

F

Finnish

National Annex See NationalAnnex, Finnish

French

Codes 451

Concrete Design 453

National Annex See NationalAnnex, French

Steel Design 459

G

GB 1591 96

GBJ 50017-2003 See SteelDesign, GBJ

50017

I

IS13920 See Concrete Design,IS13920

IS456 See Concrete Design,

IS456

IS801 See Steel Design, IS801

J

Japanese

Codes 601

Concrete Design See ConcreteDesign, AIJ

1991

Steel Design See Steel Design,AIJ 2005

M

Modulus of Elasticity 29

N

N690 Codes 823

National Annex 302, 332, 336,343

British 337

Dutch 337

Finnish 337

French 337

Norwegian 337

Polish 337

National Application Documents 275,284

NEN-EN 1993 337

NF EN 1993-1-1 337

Norwegian

Codes 923

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Index: NS-EN 1993 – Stress

National Annex See NationalAnnex, Nor-

wegian

NS-EN 1993 337

NTC 1987 See Concrete Design,NTC 1987

P

PN EN 1993-1-1 337

Polish

National Annex See NationalAnnex, Polish

S

S136-94 See Steel Design,S136-94

SAB0162-1 1993 See SteelDesign,

SAB0162-11993

SABS-0100-1 See ConcreteDesign, SABS-

0100-1

SFS EN 1993-1-1 337

SNiP 2.23-81 See Steel Design,SNiP 2.23-81

Steel Design 288, 305, 307,309, 323, 795,

801, 803

AIJ 2002 613

AIJ 2005 613, 632

ANSI/AISC N690-1994 825

AS 4100 19

ASCE 10-97 793

BS 5950-5 123

BS5400 113

BS5950 81, 108

BS8007 119

CSA CAN/CSA-S16-01 163

DIN 481

DS412 1019

EC3 301

Egyptian Code 441

Eurocode 283, 288, 301,303, 305, 307,

309, 323

French Code 459

GBJ 50017 261

IS801 593

NEN 6770 1023

NTC 1987 669

S136-94 207

SAB0162-1 1993 747

SNiP 2.23-81 715

Stress 266

Axial Compression 266

Axial Tension 266

Bending 267

Combined Loading 267

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Structural Steelwork 459

Design Rules 459

T

Timber Design

EC5 405

U

UK

National Annex See NationalAnnex, British

V

Verification Problem

AIJ 2005 643

ASME NF 3000 1974 880

ASME NF 3000 1989 893

ASME NF 3000 1998 907

ASME NF 3000 2004 919

British Cold Formed Steel 137

CSA 185, 189, 193, 197

CSA Wood 227

EC5 420, 425

SAB0162-1 763, 766, 769

W

Weld Type 97

Wood and Armer Moments 62, 121,1016,1038

Wood Design

CAN/CSA-086-01 215

Y

Yield Strength 803

Young's Modulus See Modulus ofElasticity

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