International Codes Staad Pro V8i

STAAD.Pro

V8i (SELECTseries 4)

International Design Codes ManualDAA037810-1/0005

Last updated: 11 January 2013

Copyright Information

Trademark NoticeBentley, the "B" Bentley logo, STAAD.Pro are registered or nonregistered trademarks of BentleySytems, Incorporated or Bentley Software, Inc. All other marks are the property of theirrespective owners.

Copyright Notice© 2013, Bentley Systems, Incorporated. All Rights Reserved.

Including software, file formats, and audiovisual displays; may only be used pursuant toapplicable software license agreement; contains confidential and proprietary information ofBentley Systems, Incorporated and/or third parties which is protected by copyright and tradesecret law and may not be provided or otherwise made available without proper authorization.

AcknowledgmentsWindows, Vista, SQL Server, MSDE, .NET, DirectX are registered trademarks of MicrosoftCorporation.

Adobe, the Adobe logo, Acrobat, the Acrobat logo are registered trademarks of Adobe SystemsIncorporated.

Restricted Rights LegendsIf this software is acquired for or on behalf of the United States of America, its agencies and/orinstrumentalities ("U.S. Government"), it is provided with restricted rights. This software andaccompanying documentation are "commercial computer software" and "commercialcomputer software documentation," respectively, pursuant to 48 C.F.R. 12.212 and 227.7202, and"restricted computer software" pursuant to 48 C.F.R. 52.227-19(a), as applicable. Use,modification, reproduction, release, performance, display or disclosure of this software andaccompanying documentation by the U.S. Government are subject to restrictions as set forthin this Agreement and pursuant to 48 C.F.R. 12.212, 52.227-19, 227.7202, and 1852.227-86, asapplicable. Contractor/Manufacturer is 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Unpublished - rights reserved under the Copyright Laws of the United States andInternational treaties.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.

International Design Codes Manual — i

http://www.bentley.com/bentleywebsite/files/legal/eula_en.pdf

http://www.bentley.com/bentleywebsite/files/legal/eula_en.pdf

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

Batch Design versus Design Modes 6

Batch Design 6

Design Modes 6

Section 1 Australian Codes 9

1A. Australian Codes - Concrete Design per AS 3600 - 2001 11

1B. Australian Codes - Steel Design per AS 4100 - 1998 19

Section 2 British Codes 49

2A. British Codes - Concrete Design per BS8110 51

2B. British Codes - Steel Design per BS5950:2000 67

2C. British Codes - Design per BS5400 93

2D. British Codes - Design per BS8007 97

2E. British Codes - Design per British Cold Formed Steel Code 101

Section 3 Canadian Codes 119

3A. Canadian Codes - Concrete Design per CSA Standard A23.3-94 121

3B. Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01 129

3C. Canadian Codes - Design Per Canadian Cold Formed Steel Code S136-94 165

3D. Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01 173

Section 4 Cypriot Codes 191

4A. Cypriot Codes - Concrete Design in Cyprus 193

International Design Codes Manual — iii

Section 5 Danish Codes 199

5A. Danish Codes - Steel Design per DS412 201

Section 6 Dutch Codes 205

6A. Dutch Codes - Steel Design per NEN 6770 207

Section 7 European Codes 211

7A. European Codes - Concrete Design Per Eurocode EC2 213

7B. European Codes - Steel Design to Eurocode 3 [DD ENV 1993-1-1:1992] 219

7C. European Codes - Steel Design to Eurocode 3 [EN 1993-1-1:2005] 235

7D. European Codes - National Annexes to Eurocode 3 [EN 1993-1-1:2005] 281

7E. Timber Design Per EC 5: Part 1-1 356

Section 8 Finnish Codes 376

8A. Finnish Codes - Concrete Design per B4 378

8A. Finnish Codes - Steel Design per B7 382

Section 9 French Codes 386

9A. French Codes - Concrete Design per B.A.E.L 388

9B. French Codes - Steel Design per the French Code 394

Section 10 German Codes 404

10A. German Codes - Concrete Design Per DIN 1045 406

10B. German Codes - Steel Design Per the DIN Code 414

Section 11 Indian Codes 424

11A. Indian Codes - Concrete Design per IS 456 426

11B. Indian Codes - Concrete Design per IS 13920 448

11C. Indian Codes - Steel Design per IS 800 - 1984 472

11D. Indian Codes - Steel Design per IS 802 490

11E. Indian Codes - Design per Indian Cold Formed Steel Code 512

11F. Indian Codes - Steel Design per IS 800:2007 520

Section 12 Japanese Codes 548

12A. Japanese Codes - Concrete Design Per 1991 AIJ 550

iv — STAAD.Pro

12B. Japanese Codes - Steel Design Per 2005 AIJ 558

12C. Japanese Codes - Steel Design Per 2002 AIJ 572

Section 13 Mexican Codes 590

13A. Mexican Codes - Concrete Design Per MEX NTC 1987 592

13B. Mexican Codes - Steel Design Per NTC 1987 604

Section 14 Norwegian Codes 614

14A. Norwegian Codes - Steel Design per NS 3472 / NPD 616

14B. Norwegian Codes - Steel Design per NORSOK N-004 670

14C. Norwegian Codes - Concrete Design per NS 3473 692

Section 15 Russian Codes 696

15A. Russian Codes - Concrete Design Per SNiP 2.03.01-84* 698

15B. Russian Codes - Steel Design Per SNiP 2.23-81* (Edition 1999) 726

Section 16 Singaporian Codes 744

16A. Singaporean Codes - Concrete Design per CP65 746

Section 17 South African Codes 752

17A. South African Codes - Concrete Design per SABS-0100-1 754

17B. South African Codes - Steel Design Per SAB Standard SAB0162-1:1993 760

Section 18 Spanish Codes 782

18A. Spanish Codes - Steel Design per NBE-MV103-1972 784

18A. Spanish Codes - Concrete Design per EHE 786

Section 19 Swedish Codes 790

19A. Swedish Codes - Steel Design per BSK 99 792

19B. Swedish Codes - Concrete Design per BBK 94 796

Section 20 American Aluminum Code 802

Section 21 American Transmission Tower Code 814

21A. American Transmission Tower Code - Steel Design per ASCE 10-97 816

21B. American Transmission Tower Code - Steel Design per ASCE Manuals andReports 822

International Design Codes Manual — v

Section 22 Steel Design per American PetroleumInstitute Code 828

Section 23 ANSI/AISC N690 Design Codes 844

23A. ANSI/AISC N690-1994 Code 846

23B. ANSI/AISC N690-1984 Code 862

Section 24 American Society of Mechanical Engineers –Nuclear Facility (ASME NF) Codes 882

24A. ASME NF 3000 - 1974 & 1977 Codes 884

24B. ASME NF 3000 - 1989 Code 896

24B. 18B.6 Example 904

24C. ASME NF 3000 - 2004 Code 908

24C. 18C.6 Example 918

24D. ASME NF 3000 - 2001 & 2004 Codes 922

Section 24 Technical Support 936

vi— STAAD.Pro

This documentation has been prepared to provide information pertaining to the variousinternational codes supported by STAAD. These codes are provided as additional codes byBentley Sytems, Incorporated. In other words, they do not come with the standard licensepackage. Hence, information on only some of the codes presented in this document may beactually pertinent to the license package available to you.

This document is to be used in conjunction with the STAAD Technical Reference Manual andthe STAAD Application Examples Manual. Effort has been made to provide some basicinformation about the analysis considerations and the logic used in the design approach. Abrief outline of the factors affecting the design along with references to the correspondingclauses in the codes is also provided. Examples are provided at the appropriate places tofacilitate ease of understanding of the usage of the commands and design parameters. You areurged to refer to the Examples Manual for solved problems that use the commands andfeatures of STAAD. Since the STAAD output contains references to the clauses in the code thatgovern the design, we recommend that you consult the documentation of the code of thatcountry for additional details on the design criteria.

International Design Codes Manual — 1

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

1. Graphical model generation utilities as well as text editor based commands forcreating the mathematical model. Beam and column members are represented usinglines. Walls, slabs and panel type entities are represented using triangular andquadrilateral finite elements. Solid blocks are represented using brick elements. Theseutilities allow the user to create the geometry, assign properties, orient cross sections asdesired, assign materials like steel, concrete, timber, aluminum, specify supports, applyloads explicitly as well as have the program generate loads, design parameters etc.

2. Analysis engines for performing linear elastic and pdelta analysis, finite elementanalysis, frequency extraction, and dynamic response (spectrum, time history, steadystate, etc.).

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

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

5. Peripheral tools for activities like import and export of data from and to other widelyaccepted formats, links with other popular softwares for niche areas like reinforced andprestressed concrete slab design, footing design, steel connection design, etc.

6. A library of exposed functions called OpenSTAAD which allows users to access

2— STAAD.Pro

About STAAD.Pro

STAAD.Pro’s internal functions and routines as well as its graphical commands to tapinto STAAD’s database and link input and output data to third-party software writtenusing languages like C, C++, VB, VBA, FORTRAN, Java, Delphi, etc. Thus, OpenSTAADallows users to link in-house or third-party applications with STAAD.Pro.

About STAAD.Pro


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

All the manuals can be accessed from the Help facilities of STAAD.Pro. If you want to obtaina printed copy of the books, visit the docs.bentley.com site to check availability and order.Bentley also supplies the manuals in the PDF format at no cost for those who want to printthem on their own. See the back cover of this book for addresses and phone numbers.

Getting Started and TutorialsThis manual contains information on the contents of the STAAD.Pro package, computersystem requirements, installation process, copy protection issues and a description on how torun the programs in the package. Tutorials that provide detailed and step-by-step explanationon using the programs are also provided.

Examples ManualThis book offers examples of various problems that can be solved using the STAAD engine.The examples represent various structural analyses and design problems commonlyencountered by structural engineers.

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

Technical Reference ManualThis manual deals with the theory behind the engineering calculations made by the STAADengine. It also includes an explanation of the commands available in the STAAD commandfile.

4 — STAAD.Pro

About the STAAD.Pro Documentation

Getting Started and Tutorials

http://docs.bentley.com/

International Design CodesThis document contains information on the concrete, steel, aluminum, and timber designcodes that are supported in the batch design routines. Note that most steel and concrete batchdesign routines for the US design codes can be found in the Technical Reference Manual.Details of the steel design codes supported in the post processing Steel Design Mode can befound in the User Interface manual. Details of the beam, column and slab concrete designcodes supported in the Concrete Design Mode can be found in the RC Designer manual.

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

About the STAAD.Pro Documentation


Batch Design versus Design ModesSTAAD.Pro has two means by which structural members can be designed.

Batch DesignUsing this method, code checks and/or member selection is performed directly by theanalysis and design engine when an analysis is performed.

The contents of this manual, along with those in the Technical Reference manual, are allused for batch design.

Design ModesCode checks and member selection is performed in a post-processing module for either SteelDesign or Concrete Design. These modes are available in the Graphical User Interface.

Refer to the Steel Design mode and Concrete Design mode help sections for additionalinformation.

Country/Region Code

Egypt 205 2001

Europe EC3 DD

Great Britain BS5950 2000

India IS 800

United States AISC ASD

Table 14.1-Available steel design codesin the Steel Design mode

6— STAAD.Pro

Batch Design versus Design Modes

Batch Design

Note: Design per the Chinese steel code GB50017-2003 must be performed per thelocalized STAAD SSDD interface. Please download and install this application fromBentley SELECT.

Country/Region

Code

Australia AS 3600

China GB50010

Egypt ECCS 203

EuropeEurocode 2 - 1991

Eurocode 2 - 2004

France BAEL

Germany DIN 1045-1

Great Britain BS 8110

India IS456

Japan AIJ

Norway NS3473

Russia SP52-101-03

Singapore CP65

Spain EHE

Turkey TS 500

United States

ACI 318-99

ACI 318-05 /318M-05

Table 14.2-Available design codes inthe Concrete Design codes

Batch Design versus Design Modes


8— STAAD.Pro

Section 1

Australian Codes


10 — STAAD.Pro

1A. Australian Codes - Concrete Design per AS 3600 - 2001STAAD.Pro is capable of performing concrete design based on the Australian code AS 3600-2001 Australian Standard-Concrete Structures.

Design of members per AS 3600 - 2001 requires the STAAD CAN/AUS/SA Design CodesSELECT Code Pack.

1A.1 Section Types for Concrete DesignThe 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.2 Member DimensionsConcrete members which will be designed by the program must have certain sectionproperties input under the MEMBER PROPERTY command. The following example shows therequired 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 and 250mmwidth) and the second set of members, with only depth and no width provided, will beassumed to be circular with 350 mm diameter. It is absolutely imperative that the user notprovide the cross section area (AX) as an input.

1A.3 Design ParametersThe program contains a number of parameters which are needed to perform the design.Default parameter values have been selected such that they are frequently used numbers forconventional design requirements. These values may be changed to suit the particular designbeing performed. Table 1A.1 of this manual contains a complete list of the available parametersand their default values. It is necessary to declare length and force units as Millimeter andNewton before performing the concrete design.

Note: Once a parameter is specified, its value stays at that specified number until it isspecified 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 beam members.

For column members

DEPTH YD Total depth to be used fordesign. This value defaultsto YD as provided underMEMBER PROPERTIES.

FMC 40 N/mm2 Concrete Yield Stress.Applicable values perClause 6.1.1.1 of AS 3600-2001:

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

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

12— STAAD.Pro

1A. Australian Codes - Concrete Design per AS 3600 - 2001


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

250

400

450

500

MAXMAIN 60 mm Maximum mainreinforcement bar size.

MINMAIN 10 mm Minimum mainreinforcement bar size.

MAXSEC 12 mm Maximum secondaryreinforcement bar size.

MINSEC 8 mm Minimum secondaryreinforcement bar size.

RATIO 4.0 Maximum percentage oflongitudinalreinforcement in columns.

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



TRACK 0.0 For beam design:

0.0 = output consistsof reinforcementdetails at the memberstart, middle, and end1.0 = critical momentsare printed in additionto TRACK 0.0 output2.0 = required steel forintermediate sectionsdefined by NSECTIONare printedin additionto TRACK 0.0 output

For column design:

0.0 = reinforcementdetails are printed

WIDTH ZD Width to be used fordesign. This value defaultsto ZD as provided underMEMBER PROPERTIES.

1A.4 Slenderness Effects and Analysis ConsiderationSlenderness effects are extremely important in designing compression members. There aretwo options by which the slenderness effect can be accommodated. One option is to performan exact analysis which will take into account the influence of axial loads and variablemoment of inertia on member stiffness and fixed end moments, the effect of deflections onmoment and forces and the effect of the duration of loads. Another option is toapproximately magnify design moments.

STAAD has been written to allow the use of the first option. To perform this type of analysis,use the command PDELTA ANALYSIS instead of PERFORM ANALYSIS. The PDELTA ANALYSISwill accommodate the requirements of the second- order analysis described by AS 3600,except for the effects of the duration of the loads. It is felt that this effect may be safelyignored because experts believe that the effects of the duration of loads are negligible in anormal structural configuration.

Although ignoring load duration effects is somewhat of an approximation, it must be realizedthat the evaluation of slenderness effects is also by an approximate method. In this method,additional moments are calculated based on empirical formula and assumptions on sidesway.

Considering all of the above information, a P-Delta analysis—as performed by STAAD—maybe used for the design of concrete members. However the user must note that to takeadvantage of this analysis, all the combinations of loading must be provided as primary load

14 — STAAD.Pro


cases and not as load combinations. This is due to the fact that load combinations are justalgebraic combinations of forces and moments, whereas a primary load case is revised duringthe P-delta analysis based on the deflections. Also, note that the proper factored loads (like 1.5for dead load etc.) should be provided by the user. STAAD does not factor the loadsautomatically.

1A.5 Beam DesignBeams are designed for flexure, shear and torsion. For all these forces, all active beam loadingsare prescanned to identify the critical load cases at different sections of the beams. The totalnumber of sections considered is 13 (e.g., 0., .1, .2, .25, .3, .4, .5, .6, .7, .75, .8, .9, and 1). All ofthese sections are scanned to determine the design force envelopes.

1A.5.1 Design for Flexure

Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging(creating tensile stress at the top face) moments are calculated for all active load cases at eachof the above mentioned sections. Each of these sections is designed to resist both of thesecritical sagging and hogging moments. Currently, design of singly reinforced sections only ispermitted. If the section dimensions are inadequate as a singly reinforced section, such amessage will be permitted in the 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 singlelayer of assumed reinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database in single or multiplelayers. The entire flexure design is performed again in a second pass taking into account thechanged effective depths of sections calculated on the basis of reinforcement provided after thepreliminary design. Final provisions of flexural reinforcements are made then. Efforts have beenmade to meet the guideline for the curtailment of reinforcements as per AS 3600. Although exact curtailment lengths are not mentioned explicitly in the design output (finally which willbe more or less guided by the detailer taking into account of other practical consideration),user has the choice of printing reinforcements provided by STAAD at 13 equally spaced sectionsfrom which the final detailed drawing can be prepared.

1A.5.2 Design for Shear

Shear reinforcement is calculated to resist both shear forces and torsional moments. Sheardesign is performed at 13 equally spaced sections (0. to 1.) for the maximum shear forcesamongst the active load cases and the associated torsional moments. Shear capacity calculationat different sections without the shear reinforcement is based on the actual tensilereinforcement provided by STAAD. Two-legged stirrups are provided to take care of thebalance shear forces acting on these sections.

Example of Input Data for Beam Design:

UNIT NEWTON MMS

START CONCRETE DESIGN

CODE AUSTRALIAN

FYMAIN 415 ALL


FYSEC 415 ALL

FC 35 ALL

CLEAR 25 MEM 2 TO 6

MAXMAIN 40 MEMB 2 TO 6

TRACK 1.0 MEMB 2 TO 9

DESIGN BEAM 2 TO 9

END CONCRETE DESIGN

1A.6 Column DesignColumns are designed for axial forces and biaxial moments at the ends. All active load casesare tested to calculate reinforcement. The loading which yields maximum reinforcement iscalled the critical load. Column design is done for square, rectangular and circular sections.By default, square and rectangular columns are designed with reinforcement distributed oneach side equally. That means the total number of bars will always be a multiple of four (4).This may cause slightly conservative results in some cases. All major criteria for selectinglongitudinal and transverse reinforcement as stipulated by AS 3600 have been taken care of inthe column design of STAAD.

Example of Input Data for Column Design:

UNIT NEWTON MMS


CODE AUSTRALIAN

FYMAIN 415 ALL

FC 35 ALL

CLEAR 25 MEMB 2 TO 6


DESIGN COLUMN 2 TO 6

END CONCRETE DESIGN

1A.7 Slab or Wall DesignTo 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 obtained from theelement force output (see Section 3.8 of the Technical Reference Manual). The reinforcementrequired to resist Mx moment is denoted as longitudinal reinforcement and thereinforcement required to resist My moment is denoted as transverse reinforcement. Theparameters FYMAIN, FC, MAXMAIN, MINMAIN, and CLEAR listed in Table 1A.1 are relevant to slabdesign. Other parameters mentioned in Table 1A.1 are not applicable to slab design.

16— STAAD.Pro


Figure 1A.1 - Element moments: Longitudinal (L) and Transverse (T)

Example of Input Data for Slab/Wall Design

UNIT NEWTON MMS


CODE AUSTRALIAN

FYMAIN 415 ALL

FC 25 ALL

CLEAR 40 ALL

DESIGN ELEMENT 15 TO 20

END CONCRETE DESIGN


18— STAAD.Pro

1B. Australian Codes - Steel Design per AS 4100 - 1998STAAD.Pro is capable of performing steel design based on the Australian code AS 4100-1998Standards Australia - Steel Structural Design.

Design of members per AS 3600 - 1998 requires the STAAD CAN/AUS/SA Design CodesSELECT Code Pack.

1B.1 GeneralThe design philosophy embodied in this specification is based on the concept of limit statedesign. Structures are designed and proportioned taking into consideration the limit states atwhich they would become unfit for their intended use. Two major categories of limit-state arerecognized - ultimate and serviceability. The primary considerations in ultimate limit statedesign are strength and stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all steel structures undervarious loading conditions and at the same time the chances of limits being surpassed areacceptably remote.

In the STAAD implementation, members are proportioned to resist the design loads withoutexceeding the limit states of strength, stability, and serviceability. Accordingly, the mosteconomic section is selected on the basis of the least weight criteria as augmented by thedesigner in specification of allowable member depths, desired section type, or other suchparameters. The code checking portion of the program checks whether code requirements foreach selected section are met and identifies the governing criteria.

The following sections describe the salient features of the STAAD implementation of AS 4100.A detailed description of the design process along with its underlying concepts andassumptions is available in the specification document.

1B.1.1 Strength Limit States

Strength design capacities (φRu) are calculated and compared to user-defined design actioneffects (S*), so as to ensure that S* ≤ φRu in accordance with AS 4100 3.4. Details for designcapacity calculations are outlined in the sections that follow.

1B.1.2 Deflection Limit States

STAAD.Pro’s AS 4100 implementation does not generally check deflections. It is left to theuser to check that both local member and frame deflections are within acceptable limits.

Note: Local member deflections parallel to the local member y-axis can be checked againsta user-defined maximum “span / deflection” ratio. This can be performed using theDFF, DJ1, and DJ2 design parameters, however this is only available for MEMBERDesign. Details are provided in the sections that follow.


1B.1.3 Eccentric Beam Reactions

STAAD.Pro does not automatically account for minimum eccentricity distances for beamreactions being transferred to columns as per AS 4100 4.3.4. However member offsets can beused to model these eccentricities.

Refer to Section 5.25 of the Technical Reference manual for further information on theMember Offset feature.

1B.1.4 Limit States Not Considered

The following limit states are not directly considered in STAAD.Pro’s implementation of AS4100.

Limit State CodeReference

Stability AS 4100 3.3

Serviceability AS 4100 3.5

Brittle Fracture AS 4100 3.7

Fire AS 4100 3.9

Other DesignRequirements

AS 4100 3.11

Table 1B.1-Limit States NotConsidered in STAAD.Pro AS 4100

Design

1B.1.5 Connection Design

STAAD.Pro and Bentley’s RAM Connection program currently do not support design ofconnections in accordance with AS 4100. In some cases connection design may govern thesize of members. Such considerations are not considered in STAAD.Pro’s AS 4100 and shouldbe checked by separately.

1B.1.6 Bolts and Welds

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

Note: NSC and NSF design parameters are used to manually specify a reduction in netsection area for compression or tension capacity calculations. These can be used toaccount for bolt hole area reductions. Further details are provided in the sectionsthat follow.

20 — STAAD.Pro

1B. Australian Codes - Steel Design per AS 4100 - 1998

1B.2 Analysis MethodologyEither the elastic or dynamic analysis methods may be used to obtain the forces and momentsfor design as per AS 4100 section 4.4. Analysis is done for the specified primary and repeatloading conditions. Therefore, it is your responsibility to enter all necessary loads and loadcombination factors for design in accordance with the AS/NZS 1170 Series or other relevantdesign codes. You are allowed complete flexibility in providing loading specifications andusing appropriate load factors to create necessary loading situations. Depending upon theanalysis requirements, regular stiffness analysis or P-Delta analysis may be specified. Dynamicanalysis may 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.

1B.2.1 Elastic Analysis

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

i. First Order Linear, Elastic Analysis - used to perform a regular elastic stiffness analysisas per AS 4100 4.4.2.1. Refer to Section 5.37.1 of the Technical Reference Manual foradditional details on this feature.

ii. Second Order PDelta Linear, Elastic Analysis - Depending on the type of structure, aPDelta analysis may be required in order to capture second-order effects as per AS 41004.4.1.2. Second-order effects can be captured in STAAD.Pro by performing a PDeltasecond-order elastic analysis as per AS 4100 Appendix E. Refer to Section 5.37.2 of theTechnical Reference Manual for additional details on this feature.

Note: Moment amplification as per AS 4100 clause 4.4.2 is not considered.

Hint: In order to correctly capture second-order effects for combination load casesusing a PDelta Analysis, the Repeat Load feature must be used. Second-ordereffects will not be correctly evaluated if the Load Combination feature isused. Load Combinations are combinations of results where Repeat Loadsinstruct the program to perform the analysis on the combined load actions.Refer to Section 5.32.11 of the Technical Reference Manual for additionaldetails on using Repeat Loads.

1B.2.2 Dynamic Analysis

Dynamic analysis may also be performed and the results combined with static analysis results.Refer Section 5.32.10 of the Technical Reference Manual for further information on DynamicLoading and Analysis features.


1B.3 Member Property SpecificationsFor specification of member properties, either the steel section library available in STAAD orthe User Table facility may be used. The next section describes the syntax of commands usedto assign properties from the built-in steel table. For more information on these facilities,refer to Section 1.7 the STAAD Technical Reference Manual.

1B.4 Built-in Steel Section LibraryThe following information is provided for use when the built-in steel tables are to bereferenced for member property specification. These properties are stored in a database file. Ifcalled for, the properties are also used for member design. Since the shear areas are built intothese tables, shear deformation is always considered during the analysis of these members. Anexample of the member property specification in an input file is provided at the end of thissection.

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

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

General Profile Type Australian Sections 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 columns

CHANNEL PFC Parallel flange channels

ANGLE EA, UA Equal and unequal angles

TUBE SHS, RHS Square and rectangular hollow sections

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), Bottom Cover Plates (BC), andTop & Bottom Cover Plates (TB), Double Channels (D, BA, & FR) and DoubleAngles (LD & SD). Refer to Section Profile Tables in the Graphical Environment forthese options.

Hint:When adding and assigning sections using the built-in steel section librarythrough the Graphical Environment, STAAD.Pro’s default tables are American. Tochange the default tables to Australian, select File > Configuration from theSTAAD.Pro Start page (no input file open). Set the Default Profile Table toAustralian on the Configure Program dialog Section Profile Table.

22— STAAD.Pro


Following are the descriptions of different types of sections.

1B.4.1 UB Shapes

These shapes are designated in the following way.

20 TO 30 TA ST UB150X14.0

36 TO 46 TA ST UB180X16.1

1B.4.2 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

1B.4.3 Welded Beams

Welded Beams are designated in the following way.

25 TO 35 TA ST WB700X115

23 56 TA ST WB1200X455

1B.4.4 Welded Columns

Welded Columns are designated in the following way.

25 TO 35 TA ST WC400X114

23 56 TA ST WC400X303

1B.4.5 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

1B.4.6 Double Channels

Back-to-back double channels, with or without a spacing between them, are available. Theletter 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 channel PFC230 with nospacing in between. Member 17 is a double channel PFC300 with a spacing of 0.5 length unitsbetween the channels.

1B.4.7 Angles

Two types of specification may be used to describe an angle. The standard angle section isspecified as follows:

16 20 TA ST A30X30X6

The above section signifies an angle with legs of length 30 mm and a leg thickness of 6 mm.This specification may be used when the local Z axis corresponds to the z-z axis specified inChapter 2. If the local Y axis corresponds to the z-z axis, type specification "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) inorder to be designed to AS 4100. This is to ensure that the major and minorprincipal axes align with the local member z and y axes respectively, similar toother section profiles.

1B.4.8 Double Angles

Short leg back-to-back or long leg back-to-back double angles can be specified by means ofinput of the words SD or LD, respectively, in front of the angle size. In case 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

1B.4.9 Tubes (Rectangular or Square Hollow Sections)

Tubes can be assigned in 2 ways. In the first method, the designation for the tube is as shownbelow. This method is meant for tubes whose property name is available in the steel table. Inthese examples, members 1 to 5 consist of a 2X2X0.5 inch size tube section, and members 6 to10 consist of 10X5X0.1875 inch size 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,

24 — STAAD.Pro


6 TA ST TUBE DT 8.0 WT 6.0 TH 0.5

is a tube that has a height of 8 length units, width of 6 length units, and a wall thickness of0.5 length units. Only code checking, no member selection, will be performed for TUBEsections specified in this latter manner.

1B.4.10 Pipes (Circular Hollow Sections)

Pipes can be assigned in 2 ways. In the first method, the designation for the pipe is as shownbelow. This method is meant for pipes whose property name is available in the steel table.

1 TO 5 TA ST PIP180X5

6 TO 10 TA ST PIP273X6.5

In the second method, pipe 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

specifies a pipe with outside diameter of 25 length units and inside diameter of 20 lengthunits. Only code checking, no member selection, will be performed on pipes specified in thislatter manner.

1B.4.11 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

6 TA RA A150X150X16

* DOUBLE ANGLES - SHORT LEGS BACK TO BACK

7 TA SD A65X50X5 SP 0.6

* DOUBLE ANGLES - LONG LEGS BACK TO BACK

8 TA LD A100X75X10 SP 0.75

* TUBES (RECTANGULAR OR SQUARE HOLLOW SECTIONS)


* PIPES (CIRCULAR HOLLOW SECTIONS)

10 TA ST PIPE OD 25.0 ID 20.0

PRINT MEMB PROP

FINISH

1B.5 Section ClassificationThe AS 4100 specification allows inelastic deformation of section elements. Thus, localbuckling becomes an important criterion. Steel sections are classified as compact,noncompact, or slender; depending upon their local buckling characteristics. Thisclassification is a function of the geometric properties of the section. The design proceduresare different depending on the section class. STAAD determines the section classification forthe standard shapes and user specified shapes. Design is performed for all three categories ofsection described above.

1B.6 Material PropertiesFor 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 on the Built-inMaterial Constants feature.

Refer Section 2.26.1 of the Technical Reference Manual for further information on the DefineMaterial feature.

1B.6.1 Young’s Modulus of Elasticity (E)

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

26— STAAD.Pro


C:/Windows/StaadPro20070.ini, going to the “[Material-Metric]” section, andchanging E1=205.0e6 to E1=200.0e6. Restart STAAD.Pro for this to take effect.

Warning: Virtualization features of Windows Vista and Windows 7 may requireadditional files to be modified. Contact Bentley Technical Support forassistance.

1B.7 Member ResistancesThe member resistance is calculated in STAAD according to the procedures outlined in AS4100. Calculated design capacities are compared to corresponding axial, bending moment, andshear forces determined from the STAAD.Pro analysis. These are used to report the fail or passstatus 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 resists applied loads,and accounts for cross-section yielding and local buckling effects. The nominal membercapacity on the other hand refers to the capacity of a member to resist applied loads, andincludes checks for global member buckling effects including Euler buckling, lateral-torsionalbuckling, etc.

1B.7.1 Axial Tension

The criteria governing the capacity of tension members are based on two limit states per AS4100 Section 7. The limit state of yielding of the gross section is intended to prevent excessiveelongation of the member.

The second limit state involves fracture at the section with the minimum effective net areaφNt section axial tension capacities are calculated (Cl.7.2). Through the use of the NSFparameter (see Table 1B.1), you may specify the net section area. STAAD calculates the tensioncapacity of a member based on these two limit states per Cl.7.1 and Cl.7.2 respectively of AS4100. Eccentric end connections can be taken into account using the KT correction factor,perCl.7.3. The fy yield stress is based on the minimum plate yield stress. Parameters FYLD, FU,and NSF are applicable for these calculations.

1B.7.2 Axial Compression

The compressive strength of members is based on limit states per AS 4100 Section 6. It is takenas the lesser of nominal section capacity and nominal member capacity. Nominal sectioncapacity, φNs, is a function of form factor (Cl.6.2.2), net area of the cross section, and yieldstress of the material. Through the use of the NSC parameter (see Table 1B.1), you may specifythe net section area. Note that this parameter is different from that corresponding to tension.The program automatically calculates the form factor. The kf form factors are calculated based


on effective plate widths per Cl.6.2.4, and the fy yield stress is based on the minimum plateyield stress.

Nominal member capacity, φNc, is a function of nominal section capacity and memberslenderness reduction factor (Cl.6.3.3). This value is calculated about both principal x and yaxes. Here, you are required to supply the value of αb (Cl.6.3.3) through the ALB parameter(see Table 1B.1). The effective length for the calculation of compressive strength may beprovided through the use of the parameters KY, KZ, LY, and LZ (see Table 1B.1).

1B.7.3 Bending

Bending capacities are calculated to AS 4100 Section 5. The allowable bending moment ofmembers is determined as the lesser of nominal section capacity and nominal membercapacity (ref. Cl.5.1).

The nominal section moment capacity, φMs, is calculated about both principal x and y axesand is the capacity to resist cross-section yielding or local buckling and is expressed as theproduct of the yield stress of the material and the effective section modulus (ref. Cl.5.2). Theeffective section modulus is a function of section type (i.e., compact, noncompact, orslender) and minimum plate yield stress fy. The nominal member capacity depends on overallflexural-torsional buckling of the member (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 both the web andflange 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 design segment and sub-segments are used as the basis for calculating capacities.

1B.7.4 Interaction of Axial Force and Bending

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

Note: This check is only carried out where φVv section web shear capacities arecalculated. Refer Table 1B.6-1 for details.

The member strength for sections subjected to axial compression and uniaxial or biaxialbending is obtained through the use of interaction equations. Here, the adequacy of amember is also examined against both section (ref. Cl.8.3.4) and member capacity(ref.Cl.8.4.5). These account for both in-plane and out-of-plane failures. If the summation ofthe left hand side of the equations, addressed by the above clauses, exceeds 1.0 or theallowable value provided using the RATIO parameter (see Table 1B.1), the member isconsidered to have FAILed under the loading condition.

28— STAAD.Pro


1B.7.5 Shear

Section web shear capacity, φVv, is calculated per Cl.5.11, including both shear yield and shearbuckling capacities. Once the capacity is obtained, the ratio of the shear force acting on thecross section to the shear capacity of the section is calculated. If any of the ratios (for bothlocal Y & Z-axes) exceed 1.0 or the allowable value provided using the RATIO parameter (seeTable 1B.1), the section is considered to have failed under shear.

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

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 &y principal 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 not considered.Bearing capacities are not considered.

1B.7.6 Torsion

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

1B.8 Design ParametersThe design parameters outlined in Table 1B.1 are used to control the design procedure. Theseparameters communicate design decisions from the engineer to the program and thus allowthe engineer to control the design process to suit an application's specific needs. The designscope indicates whether design parameters are applicable for MEMBER Design, PMEMBER Design,or both.

The default parameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements, some or all of theseparameter values may be changed to exactly model the physical structure.



ParameterName

Default Value DesignScope

Description

CODE - Must be specified asAUSTRALIAN to invokedesign per AS 4100 -1998.

Design Code tofollow. See section5.48.1 of the TechnicalReference Manual.

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); otherwise theinput value is used.

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.

Table 1B.4-Australian Steel Design Parameters

30 — STAAD.Pro


ParameterName


Description

BEAM 0.0 0.0 = design only forend moments andthose at locationsspecified by SECTIONcommand.

1.0 = Perform designfor moments attwelfth points alongthe beam.

DFF None (Mandatory for deflection check)

Analyticalmembersonly

“Deflection Length”/Maximum Allowablelocal deflection.

DJ1 Start Joint of member Joint No. denotingstart point forcalculation of“deflection length”

DJ2 End Joint of member Joint No. denotingend point forcalculation of“deflection length”

DMAX 45.0 [in.] Maximum allowabledepth (Applicable formember selection)

DMIN 0.0 [in.] Minimum requireddepth (Applicable formember selection)

FU 500.0 [MPa] Ultimate strength ofsteel.

FYLD 250.0 [MPa] Yield strength ofsteel.

IST 1 Steel type - 1 - SR, 2 -HR, 3 - CF, 4 - LW, 5- HW

Note: See p.47 ofAS 4100-1998.


ParameterName


Description

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 tocalculate slendernessratio.

KZ 1.0 K value for generalcolumn flexuralbuckling about thelocal Z-axis. Used tocalculate slendernessratio.

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 flexuralbuckling about thelocal Y-axis. Used tocalculate slendernessratio.

LZ Member Length Length for generalcolumn flexuralbuckling about thelocal Z-axis. Used tocalculate slendernessratio.

32— STAAD.Pro


ParameterName


Description

MAIN 0.0 A value of either 0.0or 1.0 suppresses theslenderness ratiocheck. checks are notexplicitly required perAS 4100.

Any value greaterthan 1.0 is used as thelimit for slendernessin compression.

NSC 1.0 Net section factor forcompressionmembers = An / Ag

(refer cl. 6.2.1)

NSF 1.0 Net section factor fortension members.

PBRACE None Physicalmembersonly

Refer to section 1B.11for details on thePBRACE parameter.

PHI 0.9 Capacity reductionfactor

RATIO 1.0 Permissible ratio ofactual load effect tothe design strength.

SGR 0 Steel Grade. Refer toNote a below.

0.0 = normalgrade1.0 = highstrength gradesteel

SKL 1.0 A load height factorgiven in Table 5.6.3(2)

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


ParameterName


Description

SKT 1.0 A twist restraintfactor given in Table5.6.3(1)

TRACK 0.0 Output detail

0.0 = report onlyminimum designresults1.0 = report designstrengths inaddition to TRACK0.0 output2.0 = provide fulldetails of design

UNB Member Length Unsupported lengthin bendingcompression of thebottom flange forcalculating momentresistance.

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

1B.8.1 Notes

a. DFF, DJ1, and DJ2 – Deflection calculations

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

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

Note: Deflection calculations are not applicable to PMEMBERs.

a. A straight line joining DJ1 and DJ2 is used as the reference line from whichlocal deflections are measured.

For example, refer to the figure below where a beam has been modeled using

34 — STAAD.Pro


four 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. It is important to note that unless a DFF value is specified, STAAD will notperform a deflection check. This is in accordance with the fact that there is nodefault value for DFF.

b. LHT Parameter

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

If there is any variation of the shear force and the load is acting downward determinedfrom shear force variation and load height parameter indicates the load is acting on topflange (flange at the positive local y axis) and restraints at the end of the segment is notFU (FRU) or PU (PRU) Kl is assumed to be 1.4.

If there is any variation of the shear force and the load is acting upward determinedfrom shear force variation and load height parameter indicates the load is acting on topflange (flange at the positive local y axis) and restraints at the end of the segment is notFU (FRU) or PU (PRU) Kl is assumed to be 1.0 as the load acting at the top flange iscontributing to stabilize against local torsional buckling.

c. SGR Parameter

AS 4100 defines the values of steel grades that are used as either normal steel or highgrade steel. The following table explains the material values used when either option isspecified for a particular shape:


Section Type SGR Value SteelGradeUsed

WB, WC, Tee section cut from WB andWC WB, WC, Tee section cut from WBand 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 that value will beused. Otherwise, the SGR value will be used to determine the yeild strengthand tensile strength values for the steel. based on maximum thickness ofthe individual elements of the section. Only for shear capacity calculationweb thickness is used. Similarly, Tensile Strength is determined either fromFU parameter or from SGR parameter.

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

The following example uses the Member design facility in STAAD.Pro. However, it is stronglyrecommended to use the Physical member design capabilities for AS 4100:

PARAMETER 1

CODE AUSTRALIAN

ALB 0.0 MEMBER ALL

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

36— STAAD.Pro


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

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 CODE MEMBER ALL

1B.9 Code CheckingThe purpose of code checking is to evaluate whether the provided section properties of themembers are adequate for the specified loads as per AS 4100 requirements.

Hint: Themember selection facility can be used to instruct the program to select adifferent section if the specified section is found to be inadequate.

Code checking for an analytical member is done using forces and moments at every twelfthpoint along the beam. The code checking output labels the members as PASSed or FAILed. Inaddition, the critical condition, governing load case, location (distance from the start joint)and magnitudes of the governing forces and moments are also printed. The extent of detail ofthe output can be controlled by using the TRACK parameter.

Refer to Section 2.5 of the Technical Reference Manual for general information on CodeChecking. Refer to Section 5.48.2 of the Technical Reference Manual for details thespecification 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 CODE MEMB 3 4

Note: Code checking cannot be performed on composite and prismatic sections.

1B.9.1 Physical Members

For physical members (PMEMBERs), code checks are performed at section stations positioned at1/12th points along each analytical member included in the PMEMBER. It is up to you todetermine if these locations cover critical sections for design, and adjust as necessary. Thenumber of stations for PMEMBER Design cannot be altered, however the analytical memberscan be split so that in effect more stations are checked for a PMEMBER.

For each section station along a PMEMBER, section capacity checks are carried for designactions at that station location. Member capacity checks are also carried out for each station.For these the program searches each side of the station to find adjacent effective restraintsand design forces and moments. This allows the program to determine the segment / sub-segment that the section station resides in, and then proceeds to calculate the membercapacities. Enough section stations should be included to capture all segments / sub-segments for checking.

Note:When checking combined actions for the section capacities, the design actions atthe section station are used. However when checking combined actions for themember capacities, the maximum forces from anywhere along the segment / sub-segment being considered are used. This is as stipulated in AS 4100 8.2.

The output reports whether the member has PASSed or FAILed the design checks, as well asthe critical condition, critical load case, magnitudes of design actions for the most criticalcross-section location (distance from the start joint), and complete calculations for design.The TRACK design parameter can be used to control the level of detail provided in theoutput. Color-coded results can also be viewed in the GUI’s Post Processing Beam | UnityCheck page.

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

Note: As per AS 4100 1.4, the TRACK 2.0 detailed level of output for PMEMBER Designuses x and y subscripts to refer to major and minor principal axes respectively.These differ to STAAD.Pro local member axes, where z and y refer to major andminor principal axes.

38— STAAD.Pro


1B.10 Member SelectionThis process incrementally checks increasing section profile sizes until a size is found that isAS 4100 compliant, or the largest section has been checked. Only section profiles of the sametype as modeled are incrementally checked, with the increasing sizes based on a least weightper unit length criteria.

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

Refer to Section 2.6 of the Technical Reference Manual for general information on MemberSelection. Refer to Section 5.48.3 of the Technical Reference Manual for details the specificationof 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 all memberswithin a user-defined group to take the same section size based on the most criticalgoverning design criteria for all members within that group. This is particularlyuseful when you want to use the Member Selection feature, but want a group ofelements to have the same size. Refer to Section 5.49 of the Technical ReferenceManual for information on using this feature.

Note: Member Selection will change member sizes, and hence will change the structure’sstiffness matrix. In order to correctly account for this, a subsequent analysis andCode Check should be performed to ensure that the final structure is 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

Note: Composite and prismatic sections cannot be selected.

1B.11 Tabulated Results of Steel DesignResults of code checking and member selection are presented in a tabular format. The termCRITICAL COND refers to the section of the AS 4100 specification which governs the design.


1B.12 Physical Member DesignThere 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 or higher.

Traditionally STAAD.Pro performed code checks based on single analytical members (i.e.,single members between two nodes). This implementation remains in place as shown in theexample in Section 1B.8. Physical Member (PMEMBER) Design on the other hand allows you togroup single or multiple analytical members into a single physical design member for thepurposes of design to AS 4100.

PMEMBER Design also has additional features, including:

l automated steel grades based on section type;

l automated tensile stress (fu) and yield stress (fy) values based on plate thicknesses;

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 the design ofsingle analytical members.

1B.12.1 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. Refer toSection 5.16.2 of the Technical Reference Manual for additional information.

l Graphical Environment - Using the tools in the Steel Design toolbar, members can bemanually or automatically formed. Refer to Section 1.4 of the Graphical Environmentmanual for additional information.

Note:When creating PMEMBERs for AS 4100, this must be performed in STAAD.Pro’sModeling mode. Do not use the Steel Design mode.

1B.12.2 Segment and Sub-Segment Layout

For calculation of member bending capacities about the principal x-axis, the PMEMBERDesign uses the concept of segment / sub-segment design. By default PMEMBERs areautomatically broken up into design segments and sub-segments based on calculated effectiverestraints. User-defined restraints assigned using the PBRACE design parameter are checked

40 — STAAD.Pro


to see if they are effective (i.e., if they are placed on the critical flange as per AS 4100 5.5).Restraints not applied to the critical flange are ineffective and hence are completely ignored.

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

Note: Segment and sub-segment layouts for PMEMBERs may change for different loadcases considered for design. Some restraints may be effective for one particular loadcase as they are found to apply to the critical flange, however for another load casemay be found not to act on the critical flange, and found to be ineffective. In otherwords the critical flange can change for each load case considered.

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

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

i. first all user-defined restraints are checked to see if they are applied to the compressionflange, 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 they are placed on thecritical 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 the bendingmoments at the locations of the restraints being considered. If the bending moment is zero atthe same location as a restraint then the following method is used to determine which flangeis critical at the zero moment location:

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

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

Stiffness Restraint Type

Most Stiff FR

↓ F

↓ PR

Table 1B.6-Assumed Order ofRestraint Stiffness for Zero Moment

Critical Flange


Stiffness Restraint Type

↓ P

↓ L

↓ U

Least Stiff None

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

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

For design of cantilevers, the free tip should have user-defined “U” restraints applied to bothtop and bottom flanges.

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

1B.12.3 Physical Member Restraints Specification

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

General Format

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

Where:

fn is a fraction of the PMEMBER length where restraint condition is beingspecified. This value is any ratio between 0.0 and 1.0.

rn is 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

42— STAAD.Pro


Designation,r1

RestraintType

Description

L Laterallyrestrained

Cannot be specified at theends of design members.

U Unrestrained Can only be applied at theends of design members, andmust be applied to bothflanges to be effective.

Warning: Both top andbottom flangescan not beunrestrained atthe samelocation (asthis isunstable).

FR Fully androtationallyrestrained

PR Partially androtationallyrestrained

C Continuouslyrestrained

The flange is assumed to becontinuously supported atthat flange up to nextrestraint location. Forcontinuously supportedflange unbraced 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 0.0U

PBRACE BOTTOM 0.75 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 this will be thecompression flange, except for segments with U restraint at one end, then it will be thetension flange (as is the case for cantilever portion at the end).

l when gravity loads are dominant (i.e., negative local y-axis direction), the criticalflange 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 criticalflange shall be the bottom flange (i.e., tension).

Design physical members are divided into segments by “F”, “P”, “FR”, “PR” or “U” effectivesection restraints. Segments are further broken down into sub-segments by “L” restraints, butonly if the “L” restraints are deemed to be “effective”. “L” restraints are only considered to beeffective when positioned on the “critical” flange between “F”, “P”, “FR” or “FP” restraints. Ifan “L” restraint is positioned on the non-critical flange it shall be completely ignored.Further, if an “L” restraint is positioned 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 both ends, forboth flanges.

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

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

l If SKR i.e., Kr is not provided, it is automatically calculated based on table 5.6.3(3)considering restraint conditions are the end of the segment. If FR or PR is found atonly one of the end, Kr is assumed to be 0.85; if FR or PR is found 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 Table 5.6.3(1)considering end restraints of the segment and section geometric information andsegment length.

l If SKL i.e., Kl is not provided, it is automatically calculated based on Table 5.6.3(2)considering end restraints of the segment, Load Height Position parameter, LHT andshear 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 program sortsthem automatically.

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

44 — STAAD.Pro


d. While designing any section of the member, effective restraints are searched on eachside 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 table below:

Case Flange Restrainton a CriticalFlange

Restraint ona 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

IV 1 PR or FR Nothing orU

FR

2 Nothing orU

PR or FR PR

V 1 L, P or F L, P, F, FR orPR

F

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

FR

Table 1B.8-Restraint Meanings in Critical and Noncritical Flanges

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

1B.12.4 Automated PMEMBER Design Calculations

The AS 4100 PMEMBER Design automates many design calculations, including those requiredfor segment / sub-segment design.


Automated DesignCalculations

PMEMBERDesignParameter

Comments

αb compressionmember sectionconstant per AS 41006.3.3.

ALB

αm momentmodification factor perAS 4100 5.6.1.1.

ALM Calculated based on momentsdistribution for individualsegments and sub-segments.

fu tensile strength perAS 4100 2.1.2.

FU Based on nominal steel gradespecified using SGR designparameter and section type.

fy yield stress per AS4100 2.1.1.

FYLD Based on nominal steel gradespecified using SGR designparameter and section type.

residual stress categoryfor AS 4100 Table 5.2and AS 4100 Table6.2.4.

IST Based on section type.

correction factor fordistribution of forces ina tension member perAS 4100 7.3.

KT Based on section type andeccentric end connectionspecified using EEC designparameter.

Load height positionfor automatedcalculation of the klload height factor perAS 4100 Table 5.6.3(2).

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

See "Load Height Position" onpage 47 for details.

Segment and sub-segment layout.

PBRACE Refer to the Segment and Sub-Segment Layout section abovefor details.

Nominal steel grade. SGR Based on section types.

Table 1B.9-Automated PMEMBER AS 4100 Design Parameters andCalculations

46— STAAD.Pro


Automated DesignCalculations

PMEMBERDesignParameter

Comments

kt twist restraint factoras per AS 4100 Table5.6.3(1).

SKT Based on effective end restraintsfor each segment / sub-segment.

kl load height factor asper AS 4100 Table 5.6.3(2).

SKL Based on effective end restraintsfor each segment / sub-segment,and LHT design parameter (referabove).

kr lateral rotationrestraint factor as perAS 4100 Table 5.6.3(3).

SKR Based on effective end restraintsfor each segment / sub-segment.This is where the distinctionbetween “F” and “FR”, as well as“P” and “PR” is used.

1B.12.5 Load Height Position

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

Note: This may not literally be the top flange for say a column or beam with a beta angle.The local member axes can be viewed in the GUI by selecting “Beam Orientation” inthe Diagrams Labels dialog (or Ctrl+O keyboard shortcut).

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

To determine which of these applies, the shear forces at the ends of each design segment /sub-segment is considered. If the shear force is found to have the same direction andmagnitude at both ends, it is assumed that loads act at the segment end.

If on the other hand the shear force at each end is found to have different directions ormagnitudes, loads are assumed to act within the segment.

Note: The above method includes an allowance for the self-weight of the member to beconsidered, as the self-weight always acts through the shear center.

The net sum of the end shears is also used to determine if the load is acting in the positive ornegative local member y-axis direction. If LHT is set to 1.0 for top flange loading, the net sumis used to determine whether the top flange loading is acting to stabilise or destabilise themember for lateral torsional buckling. Negative local y-axis net loads act to destabilise thesegments / sub-segments, whereas positive local y-axis net loads act to stabilise segments / sub-segments.


1B.12.6 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 BOTTOM 0.0 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

48— STAAD.Pro


Section 2

British Codes


50 — STAAD.Pro

2A. British Codes - Concrete Design per BS8110STAAD.Pro is capable of performing concrete design based on the British code BS8110-1:1997Structural use of concrete - Part 1: Code of practice for design and construction. Given thewidth and depth (or diameter for circular columns) of a section, the program will calculatethe required reinforcement to resist the forces and moments.

Design of members per BS8110-1:1997 requires the STAAD British Std Design CodesSELECT Code Pack.

Note: It is strongly recommended that you perform new concrete design using the RCDesigner Module. The following is provided to allow old STAAD files to be run.

2A.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to BS8110. These parameters not only act as a method to input required data for codecalculations but give the Engineer control over the actual design process. Default values ofcommonly used parameters for conventional design practice have been chosen as the basis.Table 2A.1 contains a complete list of available parameters with their default values.


ParameterName

DefaultValue

Description

CODE - Must be specified as BRITISH to invoke designper BS8110.

Design Code to follow. See section 5.52.2 of theTechnical Reference Manual.

BRACE 0.0 0.0 = Column braced in both directions.

1.0 = Column unbraced about local Zdirection only

2.0 = Column unbraced about local Ydirection only

3.0 = Column unbraced in both Y and Zdirections

CLEAR 20 mm Clearance of reinforcement measured fromconcrete surface to closest bar perimeter, incurrent units.

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


ParameterName

DefaultValue

Description

DEPTH YD Depth of concrete member, in current units.This value default is as provided as YD inMEMBER PROPERTIES.

EFACE 0.0 Face of support location at end of beam, incurrent units.

Note: Both SFACE & EFACE must bepositive numbers.

ELY 1.0 Member length factor about local Y directionfor column design.

ELZ 1.0 Member length factor about local Z directionfor column design.

FC 30 N/mm2 Concrete Yield Stress / cube strength, incurrent units

FYMAIN 460N/mm2

Yield Stress for main reinforcement, in currentunits (For slabs, it is for reinforcement in bothdirections)

FYSEC 460N/mm2

Yield Stress for secondary reinforcement a, incurrent units. Applicable to shear bars inbeams

MAXMAIN

50mm Maximum required reinforcement bar sizeAcceptable bars are per MINMAIN above.

MINMAIN 8mm Minimum main reinforcement bar sizeAcceptable bar sizes: 6 8 10 12 16 20 25 32 40 50

MINSEC 8mm Minimum secondary bar size a. Applicable toshear reinforcement in beams

MMAG 1.0 Factor by which column design moments aremagnified

NSECTION

10 Number of equally-spaced sections to beconsidered in finding critical moment forbeam design. The upper limit is 20.

52— STAAD.Pro

2A. British Codes - Concrete Design per BS8110

ParameterName

DefaultValue

Description

SERV 0.0 Serviceability checks:

0.0 = No serviceability checkperformed.

1.0 = Perform serviceability checkfor 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.

SFACE 0.0 Face of support location at start of beam, incurrent units. (Only applicable for shear - useMEMBER OFFSET for bending )

SRA 0.0 0.0 = Orthogonal reinforcement layoutwithout considering torsional moment Mxy -slabs only

-500 = Orthogonal reinforcement layout withMxy used to calculate Wood & Armermoments for design.

A = skew angle considered in Wood & Armerequations where A is the angle in degrees.

TRACK 0.0 0.0 = Critical Moment will not be printedwith beam design report. Column design givesno detailed results.

1.0 = For beam gives min/max steel % andspacing. For columns gives a detailed table ofoutput with additional moments calculated.

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

WIDTH ZD Width of concrete member, in current units.This value default is as provided as ZD inMEMBER PROPERTIES.

2A.2 Slenderness Effects and Analysis Considerations


STAAD provides the user with two methods of accounting for the slenderness effects in theanalysis and design of concrete members. The first method is equivalent to the procedurepresented in BS8110 Part 1 1985 Section 3.8.2.2 In this section, the code recognizes thatadditional moments induced by deflection are present and states that these 'secondary'moments are accounted for by the design formula in Section 3.8.3. This is the method usedin the design for concrete in STAAD.

Alternatively STAAD houses a PDELTA ANALYSIS facility, which allows the effects of thesesecond order moments to be considered in the analysis rather than the design. In a PDELTAanalysis, after solving the joint displacements of the structure, the additional momentsinduced in the structure are calculated. These can be compared to those calculated using theformulation of BS8110.

2A.3 Member DimensionsConcrete members that are to be designed by STAAD must have certain section propertiesinput under the MEMBER PROPERTIES command. The following example demonstrates therequired input:

UNIT MM

MEMBER PROPERTIES

*RECTANGULAR COLUMN 300MM WIDE X 450MM DEEP

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

*CIRCULAR COLUMN 300MM DIAMETER

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 x 300mm width)and the second set of members, with only depth and no width provided, will be assumed tobe circular with 300mm diameter. Note that area (AX) is not provided for these members. Ifshear area areas ( AY & AZ ) are to be considered in analysis, the user may provide them alongwith YD and ZD. Also note that if moments of inertias are not provided, the program willcalculate them from YD and ZD. Finally a T section can be considered by using the thirddefinition above.

2A.4 Beam DesignBeam design includes both flexure and shear. For both types of beam action, all active beamloadings are scanned to create moment and shear envelopes and locate the critical sections.The total number of sections considered is ten, unless that number is redefined with theNSECTION parameter. From the critical moment values, the required positive and negativebar pattern is developed with cut-off lengths calculated to include required developmentlength.

Shear design as per BS8110 clause 3.4.5 has been followed and the procedure includes criticalshear values plus torsional moments. From these values, stirrup sizes are calculated with

54 — STAAD.Pro


proper spacing. The program will scan from each end of the member and provide a total of twoshear regions at each, depending on the change of shear distribution along the beam. Iftorsion is present, the program will also consider the provisions of BS8110 - Part 2 -section 2.4.A table of shear and/or combined torsion is then provided with critical shear.

Stirrups not bent up bars are assumed in the design. The example output below shows asample output of an actual reinforcement pattern developed by STAAD. The followingannotations apply:

l LEVEL - Serial number of the bar center which may contain one or more bargroups.

l HEIGHT - Height of bar level from the soffit of the beam in relation to its local yaxis.

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

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

l TO - Distance from the start of the beam to the end of the reinforcing 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 ANCHORmm 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*8 c/c187 || 4No8 H |29. 467.TO 1500 | || ====================================================||| ||___________________________________________________________________________|_______________ _______________ _______________ _______________| | | | | | | || oooo | | oooo | | oooo | | || 4T8 | | 4T8 | | 4T8 | | || | | | | | | || | | 4T8 | | 4T8 | | 4T8 || | | oooo | | oooo | | oooo || | | | | | | ||_______________| |_______________| |_______________| |_______________|

2A.5 Column DesignColumns are designed for axial force and biaxial bending at the ends. All active loadings aretested to calculate reinforcement. The loading which produces maximum reinforcement iscalled the critical load and is displayed. The requirements of BS8110 Part 1 - section 3.8 arefollowed, with the user having control on the effective length in each direction by using theELZ and ELY parameters as described in Table 2A.1. Bracing conditions are controlled byusing the BRACE parameter. The program will then decide whether or not the column is shortor slender and whether it requires additional moment calculations. For biaxial bending, therecommendations of 3.8.4.5 of the code are considered.

Column design is done for square, rectangular and circular sections. For rectangular andsquare sections, the reinforcement is always assumed to be arranged symmetrically. Thiscauses 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 0.0 would merelygive the bar configuration, required steel area and percentage, column size and critical loadcase.

==================================================================-==

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

56— STAAD.Pro


(PROVIDE EQUAL NUMBER OF BARS AT EACH FACE)

----------------------------------------------------|BRACED /SLENDER in z E.L.z= 4500 mm (3.8.1.3 & 5)||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.6 Slab DesignSlabs are designed to BS8110 specifications. To design a slab, it must first be modeled usingfinite elements. The command specifications are in accordance with Section 5.52 of theTechnical Reference Manual.

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

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 considered thesame on both surfaces.

l SRA - Parameter which denotes the angle of the required transverse reinforcementrelative to the longitudinal reinforcement for the calculation of Wood & Armer designmoments.

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

2A.6.1 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 based on the Mxand My moments which are the direct results of STAAD analysis. The SRA parameter (SetReinforcement Angle) can be manipulated to introduce Wood & Armer moments into thedesign replacing the pure Mx, My moments. These new design moments allow the Mxymoment to be considered when designing the section. Orthogonal or skew reinforcement maybe considered. SRA set to -500 will assume an orthogonal layout. If however a skew is to beconsidered, an angle is given in degrees measured anticlockwise (positive) from the elementlocal x-axis to 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 with thelongitudinal bar being the layer closest to the slab exterior face. Typical output is 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: METRE kN || LOAD MX MY MXY MX* MY*/Ma* ANGLE || 1 -10.441 -13.347 1.270 0.000 0.000 0.000 TOP || 1 -10.441 -13.347 1.270 -11.710 -14.617 0.000 BOTT || 3 -9.541 -11.995 0.986 0.000 0.000 0.000 TOP || 3 -9.541 -11.995 0.986 -10.527 -12.981 0.000 BOTT |--------------------------------------------------------------------------

47 TOP : 195. 0.00 / 0 195. 0.00 / 0BOTT: 229. -11.71 / 1 329. -14.62 / 1

2A.7 Shear Wall DesignDesign of shear walls in accordance with BS 8110 has been added to the features of theprogram.

The program implements the provisions of BS 8110 for the design of shear walls. It performsin-plane shear, compression, as well as in-plane and out-of-plane bending design ofreinforcing. The shear wall is modeled by a single or a combination of Surface elements. Theuse of the Surface 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 and design output.The results are presented in the context of the entire wall rather than individual finiteelements thereby allowing users to quickly locate required information.

The program reports shear wall design results for each load case/combination for userspecified number of sections given by SURFACE DIVISION (default value is 10) command. Theshear wall is designed at these horizontal sections. The output includes the requiredhorizontal and vertical distributed reinforcing, the concentrated (in-plane bending)reinforcing and the link required due to out-of-plane shear.

2A.7.1 Design Parameters

START SHEARWALL DESIGN

CODE BRITISH

shearwall-parameters

DESIGN SHEARWALL LIST shearwall-list

END

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


58— STAAD.Pro


ParameterName

DefaultValue

Description

FYMAIN460Mpa

Yield strength of steel, in current units.

FC 30 MpaCompressive strength of concrete, in currentunits.

HMIN 6

Minimum size of horizontal reinforcing bars(range 6 mm – 36 mm). If input is 6 (integernumber) the program will assume 6 mmdiameter bar.

HMAX 36

Maximum size of horizontal reinforcing bars(range 6 mm – 36 mm). If input is 6 (integernumber) the program will assume 6 mmdiameter bar.

VMIN 6

Minimum size of vertical reinforcing bars(range 6mm – 36mm). If input is 6 (integernumber) the program will assume 6 mmdiameter bar.

VMAX 36

Maximum size of vertical reinforcing bars(range 6mm – 36mm). If input is 6 (integernumber) the program will assume 6 mmdiameter bar.

EMIN 6

Minimum size of vertical reinforcing barslocated in edge zones (range 6mm – 36mm).If input is 6 (integer number) the programwill assume 6 mm diameter bar.

EMAX 36

Maximum size of vertical reinforcing barslocated in edge zones (range 6mm – 36mm).If input is 6 (integer number) the programwill assume 6 mm diameter bar.

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

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

CLEAR 25 mm Clear concrete cover, in current units.

Table 2A.2-Shear Wall Design Parameters


ParameterName

DefaultValue

Description

TWOLAYERED 0

Reinforcement placement mode:

0. single layer, each direction

1. two layers, each direction

KSLENDER 1.5Slenderness factor for finding effectiveheight.

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

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

3. The SUPPORTS command includes the new support generation routine. For instance,the line 2 TO 5GEN PIN assigns pinned supports to all nodes between nodes 2 and 5.As the node-to-node distances were previously subdivided by the SET DIVISION 12command, there will be an additional 11 nodes between nodes 2 and 5. As a result, all13 nodes will be assigned pinned supports. Please note that the additional 11 nodes arenot individually accessible to the user. They are created by the program to enable thefinite element mesh generation and to allow application of boundary constraints.

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

5. The shear wall design commands are listed between lines START SHEARWALL DESand END. The CODE command selects the design code that will be the basis for thedesign. For British code the parameter is BRITISH. The DESIGN SHEARWALL LISTcommand is followed by a list of previously defined Surface elements intended as shearwalls and/or shear wall components.

2A.7.2 Technical Overview

The program implements provisions of section 3.9 of BS 8110:Part 1:1997 and relevantprovisions as referenced therein, for all active load cases. The wall is designed as unbracedreinforced wall. The following steps are performed for each of the horizontal sections of thewall 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-plane direction, thewall is assumed to be simply supported. Hence, the provisions of clause 3.9.3.2.2 and 3.9.4.2 areapplicable. The default effective height is 1.5 times the clear height. User can change theeffective height. The limit for slenderness is as per table 3.23 for unbraced wall, which is takenas 30.

60 — STAAD.Pro


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

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

Extreme compression fibre to centroid of tension (concentrated) reinforcement distance, d, istaken as 0.8 horizontal length of the wall. Flexural design of the wall is carried out inaccordance with the provisions of clause no. 3.4.4. The flexural (concentrated vertical )reinforcing is located at both ends (edges) of the length of the wall. The edge reinforcement isassumed to be distributed over a length of 0.2 times horizontal length on each side. Thislength is inclusive of the thickness of the wall. Minimum reinforcements are according totable 3.25.

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

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 into consideration theeffect of axial load. The area of reinforcement is calculated and checked against the minimumarea as per clause no. 3.12.7.4.

Design for compression and out-of-plane vertical bending

This is denoted by Fy and My respectively in the shear wall force output.

The wall panel is designed as simply supported (at top and bottom), axially loaded with out-of-plane uniform lateral load, with maximum moments and deflections occurring at mid-height. Design is done as per clause no. 3.8.4 for axially loaded column with uni-axial bending.The minimum reinforcement percentage is as per table 3.25. The maximum reinforcementpercentage of vertical reinforcement is as per clause no. 3.12.6.3. Links if necessary are calculatedas per the provisions of clause 3.12.7.5.

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

The out-of-plane shear arises from out-of-plane loading. The design shear stress is calculated asper 3.4.5.2 and shear strength of concrete section is calculated as per table 3.8 consideringvertical reinforcement as tension reinforcement.

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


Design for out-of-plane horizontal bending (denoted by Mx in theshear wall force output)

The horizontal reinforcement already calculated from in-plane shear is checked against thewhole section subjected to out-of-plane bending and axial load. The axial load in this case isthe in-plane shear. The section is again designed as axially loaded column under uni-axialbending as per the provisions of clause 3.8.4. Extra reinforcement in the form of horizontalbars, if necessary, is reported.

2A.7.3 Example

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

.

.

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

.

62— STAAD.Pro


.

START SHEARWALL DES

CODE BRITISH

UNIT NEW MMS

FC 25

FYMAIN 460

TWO 1

VMIN 12

HMIN 12

EMIN 12

DESIGN SHEA LIST 1 TO 4

END

2A.7.4 Shear Wall Design With Opening

The Surface element has been enhanced to allow design of shear walls with rectangularopenings. The automatic meshing algorithm has been improved to allow variable divisionsalong wall and opening(s) edges. Design and output are available for user selected locations.

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

Shear wall set-up

Definition of a shear wall starts with a specification of the surface element perimeter nodes,meshing divisions along node-to-node segments, opening(s) corner coordinates, and meshingdivisions of four edges of the opening(s).

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

RECOPENING x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4 DIVISION od1, ..., 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-node distance on thesurface 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 all node-to-node segments, or if any of the numbers listed equals zero, then the


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 set as 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 of the surfacewhere output is requested. The output is provided for sections located betweendivision segments. For example, if the number of divisions = 2, then the outputwill be produced for only one section (at the center of the edge).

Stress/force output printing

Values of internal forces may be printed out for any user-defined section of the wall. Thegeneral 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 the fullcross-section of the wall,

d1, d2 - coordinates in the direction orthogonal to ξ, delineating a fragmentof 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 is directed away fromthe surface, the negative range is to be entered.

Note: If command ALONG is omitted, direction Y (default) is assumed. If command ATis omitted, output is provided for all sections along the specified (or default) edge.Number of sections will be determined from the SURFACE DIVISION X orSURFACE DIVISION Y input values. If the BETWEEN command is omitted, theoutput is generated based on full cross-section width.

64 — STAAD.Pro


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 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.

Shear wall design

The program implements different provisions of design of walls as per code BS 8110. Generalsyntax of the design command is as follows:


(...)

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 the wall or panels,as applicable, defined by the SURFACE DIVISION X or SURFACE DIVISION Y input values.

a. No panel definition.

Design is performed for the specified horizontal full cross-section, located at a distancec from the origin of the local coordinates system. If opening is found thenreinforcement is provided along sides of openings. The area of horizontal and verticalbars provided along edges of openings is equal to that of the respective interrupted bars.

b. Panels have been defined.


Design is performed for all panels, for the cross-section located at a distance c from thestart of the panel.

66— STAAD.Pro


2B. British Codes - Steel Design per BS5950:2000STAAD.Pro is capable of performing steel design based on the British code BS 5950-1:2000Structural use of steelwork in building - Part 1: Code of practice for design - Rolled and weldedsections, Incorporating Corrigendum No. 1.

Design of members per BS 5950-1:2000 requires the STAAD British Std Design CodesSELECT Code Pack.

2B.1 GeneralThe design philosophy embodied in BS5950:2000 is built around the concept of limit statedesign, used today in most modern steel design codes. Structures are designed andproportioned taking into consideration the limit states at which they become unfit for theirintended use. Two major categories of limit state are recognized - serviceability and ultimate.The primary considerations in ultimate limit state design are strength and stability while thatin serviceability limit state is deflection. Appropriate safety factors are used so that the chancesof limits being surpassed are acceptably remote.

In the STAAD implementation of BS5950:2000, members are proportioned to resist the designloads without exceeding the limit states of strength and stability. Accordingly, the mosteconomic section is selected on the basis of the least weight criteria. This procedure iscontrolled by the designer in specification of allowable member depths, desired section type orother such parameters. The code checking portion of the program checks that coderequirements for each selected section are met and identifies the governing criteria.

The complete B.S.C. steel tables for both hot rolled and hollow sections are built into theprogram for use in specifying member properties as well as for the actual design process. Seesection 2B.4 for information regarding the referencing of these sections. In addition touniversal beams, columns, joists, piles, channels, tees, composite sections, beams with coverplates, pipes, tubes, and angles, there is a provision 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 a complete description.

Single Angle Sections

Angle sections are un-symmetrical and when using BS 5950:2000 table 25 you must considerfour axes: two principal, u-u and v-v and two geometric, a-a and b-b. The effective length forthe v-v axis, Lvv, is taken as the LVV parameter or LY · KY, if not specified. The a-a and b-baxes are determined by which leg of the angle is fixed by the connection and should bespecified using the LEG parameter, see section 5B.6 for more information on the LEGparameter. The effective length in the a-a axis is taken as LY · KY and the effective length inthe b-b axis as LZ · KZ.

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


Figure 2B.1 - Axis orientation for single angles

ST angle andUSER table angles

RA angle

2B.2 Analysis MethodologyElastic analysis method is used to obtain the forces and moments for design. Analysis is donefor the primary and combination loading conditions provided by the user. The user is allowedcomplete flexibility in providing loading specifications and using appropriate load factors tocreate necessary loading situations. Depending upon the analysis requirements, regularstiffness analysis or P-Delta analysis may be specified. Dynamic analysis may also be performedand the results combined with static analysis results.

2B.3 Member Property SpecificationsFor specification of member properties, the steel section library available in STAAD may beused. The next section describes the syntax of commands used to assign properties from thebuilt-in steel table. Member properties may also be specified using the User Table facility. Anyuser-defined section may be specified, except for GENERAL or PRISMATIC sections. For moreinformation on these facilities, refer to Section 1.7 the STAAD Technical Reference Manual.

2B.4 Built-In Steel Section LibraryThe following information is provided for use when the built-in steel tables are to bereferenced for member property specification. These properties are stored in a database file. Ifcalled for, the properties are also used for member design. Since the shear areas are built intothese tables, shear deformation is always considered during the analysis of these members.

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


Following are the descriptions of different types of sections available:

68— STAAD.Pro

2B. British Codes - Steel Design per BS5950:2000

2B.4.1 Universal Beams, Columns, and Piles

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

20 TO 30 TA ST UB305X165X54

33 36 TA ST UC356X406X287

100 102 106 TA ST UP305X305X186

2B.4.2 Rolled Steel Joists

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

10 TO 20 TA ST JO152X127

1 2 TA ST JO127X114A

2B.4.3 Channels

All rolled steel channel sections from the BSI table have been incorporated in STAAD. Thedesignation is similar to that of the joists. The same designation scheme as in BSI tables maybe used with the weight omitted.

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


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., 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 CODE command.

2B.4.5 Tee Sections

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

54 55 56 TA T UB254X102X22


(tee cut from UB254X102X22)

2B.4.6 Angles

All equal and unequal angles are available for analysis. Two types of specifications may be usedto describe an angle section, either a standard, ST specification or reversed angle, RAspecification. Note, however, that only angles specified with an RA specification can bedesigned.

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-V axisspecified in the steel tables. If the local STAAD y-axis corresponds to the V-V axis in thetables, type specification "RA" (reverse angle) may be used.

35 TO 45 TA RA UA200X150X18


Short leg back-to-back or long leg back-to-back double angles can be specified by inputtingthe word SD or LD, respectively, in front of the angle size. In case of an equal angle, either LDor 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 of gyrationabout an individual sections’ principal v-v axis (See Technical Reference Manual,5.19 User Steel Table Specification)


To designate circular hollow sections from BSI tables, use PIP followed by the numericalvalue of diameter and thickness of the section in mm omitting the decimal section of thevalue provided for diameter. The following example will illustrate 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 inside diametersof the section. For example,

70 — STAAD.Pro



(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 of specification isused.

2B.4.9 Rectangular or Square Hollow Sections (Tubes)

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

Figure 2B.2 - BSI tube nomenclature

Example:

15 TO 25 TA ST TUB160808.0

Tubes, like pipes, can also be input by their dimensions (Height, Width and Thickness) andnot by any table designations.


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

Note: Only code checking and no member selection is performed for TUBE sectionsspecified this way.

2B.5 Member CapacitiesThe basic measure of capacity of a beam is taken as the plastic moment of the section. This is asignificant departure from the standard practice followed in BS449, in which the limitingcondition was attainment of yield stress at the extreme fibres of a given section. With theintroduction of the plastic moment as the basic measure of capacity, careful considerationmust be given to the influence of local buckling on moment capacity. To assist this, sectionsare classified as either Class 1, plastic, Class 2, compact, Class 3, semi-compact or Class 4,slender, which governs the decision whether to use the plastic or the elastic moment capacity.The section classification is a function of the geometric properties of the section. STAAD iscapable of determining the section classification for both hot rolled and built up sections. Inaddition, for slender sections, BS5950 recommends the use of a 'stress reduction factor' to


reduce the design strength. This factor is again a function of the geometry of the section andis automatically determined by STAAD for use in the design process.

2B.5.1 Axial Tension

In members with axial tension, the tensile load must not exceed the tension capacity of themember. The tension capacity of the member is calculated on the basis of the effective area asoutlined in Section 4.6 of the code. STAAD calculates the tension capacity of a given memberper this procedure, based on a user supplied net section factor (NSF-a default value of 1.0 ispresent but may be altered by changing the input value - see Table 2B.1), proceeding withmember selection or code check accordingly. BS5950 does not have any slendernesslimitations for tension members.

2B.5.2 Compression

Compression members must be designed so that the compression resistance of the member isgreater than the axial compressive load. Compression resistance is determined according tothe compressive strength, which is a function of the slenderness of the gross section, theappropriate design strength and the relevant strut characteristics. Strut characteristics takeinto account the considerable influence residual rolling and welding stresses have on columnbehavior. Based on data collected from extensive research, it has been determined thatsections such as tubes with low residual stresses and Universal Beams and Columns are ofintermediate performance. It has been found that I-shaped sections are less sensitive toimperfections when constrained to fail about an axis parallel to the flanges. These researchobservations are incorporated in BS5950 through the use of four strut curves together with aselection of tables to indicate which curve to use for a particular case. Compression strengthfor a particular section is calculated in STAAD according to the procedure outlined in AnnexC of BS5950 where compression strength is seen to be a function of the appropriate Robertsonconstant ( representing Strut Curve) corresponding Perry factor, limiting slenderness of themember and appropriate design strength.

A departure from BS5950:1990, generally compression members are no longer required to bechecked for slenderness limitations, however, this option can be included by specifying aMAIN parameter. Note, a slenderness limit of 50 is still applied on double angles checked asbattened struts as per clause 4.7.9.

2B.5.3 Axially Loaded Members With Moments

In the case of axially loaded members with moments, the moment capacity of the membermust be calculated about both principal axes and all axial forces must be taken into account.If the section is plastic or compact, plastic moment capacities will constitute the basicmoment capacities subject to an elastic limitation. The purpose of this elastic limitation is toprevent plasticity at working load. For semi-compact or slender sections, the elastic momentis used. For plastic or compact sections with high shear loads, the plastic modulus has to bereduced to accommodate the shear loads. The STAAD implementation of BS5950 incorporatesthe procedure outlined in section 4.2.5 and 4.2.6 to calculate the appropriate momentcapacities of the section.

72— STAAD.Pro


For members with axial tension and moment, the interaction formula as outlined in section4.8.2 is applied based on effective tension capacity.

For members with axial compression and moment, two principal interaction formulae must besatisfied – Cross Section Capacity check (4.8.3.2) and the Member Buckling Resistance check(4.8.3.3 ). Three types of approach for the member buckling resistance check have beenoutlined in BS5950:2000 - the simplified approach (4.8.3.3.1), the more exact approach (4.8.3.3.2)and Annex I1 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 be moreconservative than the simplified approach. It has been found, however, that this is not alwaysthe case and STAAD therefore performs both checks, comparing the results in order that themore appropriate criteria can be used.

Additionally the equivalent moment factors, mx my and myx, can be specified by the user orcalculated by the program.

Members subject to biaxial moments in the absence of both tensile and compressive axialforces are checked using the appropriate method described above with all axial forces set tozero. STAAD also carries out cross checks for compression only, which for compact/plasticsections may be more critical. If this is the case, COMPRESSION will be the critical conditionreported despite the presence of moments.

2B.5.4 Shear

A member subjected to shear is considered adequate if the shear capacity of the section isgreater than the shear load on the member. Shear capacity is calculated in STAAD using theprocedure outlined in section 4.2.3, also 4.4.5 and Annex H3 if appropriate, considering theappropriate shear area for the section specified.

2B.5.5 Lateral Torsional Buckling

Since plastic moment capacity is the basic moment capacity used in BS5950, members arelikely to experience relatively large deflections. This effect, coupled with lateral torsionalbuckling, may result in severe serviceability limit state. Hence, lateral torsional buckling mustbe considered carefully.

The procedure to check for lateral torsional buckling as outlined in section 4.3 has beenincorporated in the STAAD implementation of BS5950. According to this procedure, for amember subjected to moments about the major axis, the 'equivalent uniform moment' on thesection must be less than the lateral torsional buckling resistance moment. For calculation ofthe buckling resistance moment, the procedure outlined in Annex B.2 has been implementedfor all sections with the exception of angles. In Annex B.2., the resistance moment is given as afunction of the elastic critical moment, Perry coefficient, and limiting equivalent slenderness,which are calculated within the program; and the equivalent moment factor, mLT, which isdetermined as a function of the loading configuration and the nature of the load (stabilizing,destabilizing, etc).


2B.5.6 RHS Sections - Additional Provisions

Rectangular Hollow sections are treated in accordance with S.C.I. recommendations in caseswhen the plastic axis is in the flange. In such cases, the following expressions are used tocalculate the reduced plastic moduli:

For n ≥ 2t(D-2t)/A

=

−

+ − −

−S n n1 1rx

A

B t

D B t

A4( )

2 ( )2

For n ≥ 2t(B-2t)/A

=

−

+ − −

−S n n1 1ry

A

D t

B D t

A4( )

2 ( )2

2B.6 Design ParametersAvailable design parameters to be used in conjunction with BS5950 are listed in table 2B.1along with their default values.

Note: 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.

ParameterName

Default Value Description

CODE -

Must be specified as BS5950


See section 5.48.1 of the TechnicalReference Manual.

AD Depth at end/2Distance between the reference axisand the axis of restraint. See G.2.3

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

74 — STAAD.Pro


ParameterName


BEAM 3.0

Beam divisions

0. Design only for endmoments or those locationsspecified by the SECTIONcommand.

1. Calculate forces andmoments at 12th pointsalong the member. Establishthe location where Mz is themaximum. Use the forcesand moments at thatlocation. Clause checks atone location.

2. Same as BEAM = 1.0 butadditional checks are carriedout for each end.

3. Calculate moments at 12th

points along the member. Clause checks at eachlocation including the endsof the member.

CAN 0

Deflection check method. See Note1 below.

0. Deflection check based onthe principle that maximumdeflection occurs within thespan between DJ1 and DJ2.

1. Deflection check based onthe principle that maximumdeflection is of thecantilever type (see notebelow)


ParameterName


CB 1.0

Moment calculation:

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

2. To calculate Mbs (simple) asper Clause 4.7.7 as opposedto Mb.

DFF

None(Mandatory fordeflection check,TRACK 4.0)

"Deflection Length" / Maxm.allowable local deflection

See Note 1d below.

DJ1Start Jointof member

Joint No. denoting starting pointfor calculation of "DeflectionLength."

See Note 1 below.

DJ2End Joint ofmember

Joint No. denoting end point forcalculation of "Deflection Length."

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 and 4.8.3.3.2

0.0 = Fail ratio usesMIN of 4.8.3.3.1,4.8.3.3.2. and Annex I1checks.

1.0 = Fail ratio usesMAX of 4.8.3.3.1,4.8.3.3.2. and Annex I1checks.

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.

76— STAAD.Pro


ParameterName


LEG 0.0

Valid range from 0 – 7 and 10. Thevalues correspond to table 25 ofBS5950 for fastener conditions. Seenote 2 below.

LVV *

Maximum of Lyy

and Lzz(Lyy is a term

usedby BS5950)

Used in conjunction with LEG forLvv as per BS5950 table 25 fordouble angles. See note 6 below.

LY * Member LengthLength in local y - axis (currentunits) to calculate (KY)(LY)/Ryyslenderness ratio.

LZ * Member LengthLength in local z - axis (currentunits) to calculate (KZ)(LZ)/Rzzslenderness ratio.

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 1.0Equivalent moment factor forminor axis lateral flexural bucklingas defined in clause 4.8.3.3.4

NSF 1.0Net section factor for tensionmembers.

PNL * 0.0

Transverse stiffener spacing (‘a’ inAnnex H1)

0.0 = Infinity

Any other value used in thecalculations.


ParameterName


PY *Set according tosteel grade (SGR)

Design strength of steel

MAIN 0.0

Slenderness limit for memberswith compression forces, effectivelength/ radius of gyration, for agiven axis:

0.0 = Slendernessnot performed.

1.0 = Main structuralmember (180)

2.0 = Secondarymember. (250)

3.0 = Bracing etc(350)

RATIO 1.0Permissible ratio of the actualcapacities.

SAME** 0.0

Controls the sections to try duringa SELECT process.

0.0 = Try everysection of the sametype as original

1.0 = Try only thosesections with asimilar name asoriginal, e.g., if theoriginal is an HEA100, then only HEAsections will beselected, even if thereare HEM’s in thesame table.

78— STAAD.Pro


ParameterName


SBLT 0.0

Identify Section type for sectionclassification

0.0 = Rolled Section

1.0 = Built upSection

2.0 = Cold formedsection

SWAY none

Specifies a load case number toprovide the sway loading forces inclause 4.8.3.3.4 (See additionalnotes)

SGR 0.0

Steel Grade per BS4360

0.0 = Grade S 275

1.0 = Grade S 355

2.0 = Grade S 460

3.0 = As per GB 1591– 16 Mn

TB 0.0

LImit of moment capacity in Cl4.2.5.1:

0 = Mc limit 1.5pyZ

1= Mc limit 1.2 pyZ

TRACK 0.0

Output details

0.0 = Suppress allmember capacityinfo.

1.0 = Print allmember capacities.

2.0 = Print detaileddesign sheet.

4.0 = DeflectionCheck (separatecheck to main select/ check code)


ParameterName


UNF 1.0

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

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 steel design

1.0 = Closedsections. Welding onone side only (exceptfor webs of wideflange and teesections)

2.0 = Opensections. Welding onboth sides (exceptpipes and tubes)

* current units must be considered.

**For angles, if the original section is an equal angle, then the selected section will be anequal 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.

2B.6.1 Notes

1. CAN, DJ1, and DJ2 – Deflection

a. When performing the deflection check, you can choose between two methods.The first method, defined by a value 0 for the CAN parameter, is based on thelocal displacement. Local displacement is described in Section 5.44 of theTechnical Reference Manual.

If the CAN parameter is set to 1, the check will be based on cantilever styledeflection. Let (DX1, DY1, DZ1) represent the nodal displacements (in globalaxes) at the node defined by DJ1 (or in the absence of DJ1, the start node of themember). Similarly, (DX2, DY2, DZ2) represent the deflection values at DJ2 orthe end node of the member.

80 — STAAD.Pro



Compute Length = distance between DJ1 & DJ2 or, between start node and endnode, 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 for calculationof local 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 line joiningDJ1 and DJ2 is used as the reference line from which local deflections aremeasured.

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.


PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

c. If DJ1 and DJ2 are not used, "Deflection Length" will default to the memberlength and local deflections will be measured from original member line.

d. It is important to note that unless a DFF value is specified, STAAD will notperform a deflection check. This is in accordance with the fact that there is nodefault 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 the fastenerrestraint conditions for angles, double angles, tee sections and channels for slenderness.The following values are available:


ClauseBold

ConfigurationLeg

LEGParameter

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

4.7.10.4 Channels(a) - 2 or more rows of bolts 1.0

(b) - 1 row of bolts 0.0

4.7.10.5 TeeSections

(a) - 2 or more rows of bolts 1.0


Table 2B.2- LEG Parameter values

The slenderness of single and double angle, channel and tee sections are specified inBS 5950 table 25 depending on the connection provided at the end of the member. Todefine the appropriate connection, a LEG parameter should be assigned to the member.

The following list indicates the value of the LEG parameter required to match theBS5950 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-a and b-b aswell as the weak v-v axis. The effective lengths of the geometric axes are defined as:

La = KY * KY

Lb = KZ * LZ

82— STAAD.Pro


The slenderness calculated for the v-v axis is then used to calculate the compressionstrength pc for the weaker principal axis (z-z for ST angles or y-y for RA specifiedangles). The maximum slenderness of the a-a and b-b axes is used to calculate thecompression strength pc for the stronger principal axis.

Alternatively for single angles where the connection is not known or Table 25 is notappropriate, by setting the LEG parameter to 10, slenderness is calculated for the twoprincipal axes y-y and z-z only. The LVV parameter is not used.

For double angles, the LVV parameter is available to comply with note 5 in table 25. Inaddition, if using double angles from user tables, (Technical Reference Manual section5.19) an eleventh value, rvv, should be supplied at the end of the ten existing valuescorresponding to the radius of gyration of the single angle making up the pair.

3. PY – Steel Design Strength

The design parameter PY should only be used when a uniform design strength for anentire structure or a portion thereof is required. Otherwise the value of PY will be setaccording to the stipulations of BS5950 table 9 in which the design strength is seen as afunction of cross sectional thickness for a particular steel grade (SGR parameter) andparticular element considered. Generally speaking this option is not required and theprogram should be allowed 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 than zero incurrent units of length. They are supplied along with or instead of UNF, KY and KZ(which are factors, not lengths) to define lateral torsional buckling and compressioneffective lengths respectively. Please note that both UNL or UNF and LY or KY valuesare required even though they are often the same values. The former relates tocompression flange restraint for lateral torsional buckling while the latter is theunrestrained buckling length for compression checks.

5. TRACK – Control of Output Formats

When the TRACK parameter is set to 0.0, 1.0, or 2.0, member capacities will be printed indesign related output (code check or member selection) in kilonewtons per squaremeter.

TRACK 4.0 causes the design to carry out a deflection check, usually with a differentload list to the main code check. The members that are to be checked must have theparameters DFF, DJ1, and DJ2 set.

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

The values for the equivalent moment factors can either be specified directly by the useras a positive value between 0.4 and 1.0 for MX, MY and MYX and 0.44 and 1.0 for MLT.


The program can be used to calculate the values for the equivalent moment factors bydefining the design member with a GROUP command (see the Technical ReferenceManual section 5.16 Listing of Members/Elements/Joints by Specification of GROUPS).The nodes along the beam can then be defined as the location of restraint points withJ settings.

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

For example, consider a series of 5 beam elements as a single continuous member asshown below:

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

START GROUP DEFINITION

MEMBER

_MAINBEAM 11 2 38 12 3

END GROUP DEFINITION

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

Therefore, this 5 beam member has 6 joints such that:

Joint 1 = Node 3

Joint 2 = Node 1

Joint 3 = Node 33

84 — STAAD.Pro


Joint 4 = Node 14

Joint 5 = Node 7

Joint 6 = Node 2

a. Consider MX, MY and MYX

Say that this member has been restrained in its’ major axis (local Y) only at theends. In the minor axis (local Z) it has been restrained at the ends and also atnode number 33 (joint 3). For local flexural buckling, it has only been restrainedat 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 torsional bucklingand the top flange has been restrained at node number 33 (joint 3) and only the lowerflange at node number 7, (joint 5). Hence:

MLT _MainBeam J1 T3 L5 J6

To split the beam into two buckling lengths for Ly at 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 sway load case inthe context of clause 4.8.3.3.4. This load case would be set up to represent the kampMsmentioned in this clause and the steel design module would add the forces from thisload case to the forces of the other load case it is designed for.

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

ParameterName


SWAY (load casenumber)

ALL

MEMBER (member list)

_(group name)


Example

SWAY 5 MEM 1 TO 10

SWAY 6 _MAINBEAMS

2B.7 Design OperationsSTAAD contains a broad set of facilities for the design of structural members as individualcomponents of an analyzed structure. The member design facilities provide the user with theability to carry out a number of different design operations. These facilities may be usedselectively in accordance with the requirements 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 load cases.

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

l Specify whether to perform code checking or member selection along with the list ofmembers.

These operations may be repeated by the user any number of times depending upon thedesign requirements.

2B.8 Code CheckingThe purpose of code checking is to ascertain whether the provided section properties of themembers are adequate. The adequacy is checked as per BS5950. Code checking is done usingthe forces and moments at specific sections of the members. If no sections are specified, theprogram uses the start and end forces for code checking.

When code checking is selected, the program calculates and prints whether the membershave passed or failed the checks; the critical condition of BS5950 code (like any of the BS5950specifications for compression, tension, shear, etc.); the value of the ratio of the criticalcondition (overstressed for value more than 1.0 or any other specified RATIO value); thegoverning load case, and the location (distance from the start of the member of forces in themember where the critical condition occurs).

Code checking can be done with any type of steel section listed in Section 2B.4 or any of theuser defined sections as described in Section 1.7.3 of the Technical Reference Manual, exceptprofiles defined in GENERAL and ISECTION tables.

Note: PRISMATIC sections are also not acceptable steel sections for design per BS5950 inSTAAD.Pro.


86— STAAD.Pro


2B.9 Member SelectionSTAAD is capable of performing design operations on specified members. Once an analysis hasbeen performed, the program can select the most economical section, i.e., the lightest section,which fulfills the code requirements for the specified member. The section selected will be ofthe same type section as originally designated for the member being designed. Memberselection can also be constrained by the parameters DMAX and DMIN, which limits themaximum and minimum depth of the members.

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

Selection of members, whose properties are originally input from a user created table, will belimited to sections in the user table.

Member selection cannot be performed on members whose section properties are input asprismatic or as above limitations for code checking.


2B.10 Tabulated Results of Steel DesignFor code checking or member selection, the program produces the results in a tabulatedfashion. The items in the output table are explained as follows:

MEMBERrefers to the member number for which the design is performed.

TABLErefers to steel section name, which has been checked against the steel code or hasbeen selected.

RESULTSprints whether the member has PASSED or FAILED. If the RESULT is FAIL, therewill be an asterisk (*) mark on front of the member.

CRITICAL CONDrefers to the section of the BS5950 code which governs the design.

RATIOprints the ratio of the actual stresses to allowable stresses for the critical condition.Normally a value of 1.0 or less will mean the member has passed.

LOADINGprovides the load case number, which governed the design

FX, MY, and MZprovide the axial force, moment in local Y-axis and the moment in local z-axisrespectively. Although STAAD does consider all the member forces and moments(except torsion) to perform design, only FX, MY and MZ are printed since they arethe ones which are of interest, in most cases.


LOCATIONspecifies the actual distance from the start of the member to the section wheredesign forces govern.

TRACKIf the parameter TRACK is set to 1.0, the program will block out part of the tableand will print the allowable bending capacities in compression (MCY & MCZ) andreduced moment capacities (MRY & MRZ), allowable axial capacity in compression(PC) and tension (PT) and shear capacity (PV). TRACK 2.0 will produce the designresults as shown in section 2B.9.

An example of each TRACK setting follows:

2B.10.1 Example output for TRACK 0.0MEMBER 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


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 ||---------------------------------------------------------------------|


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 : 1960.000 895.000

88— STAAD.Pro


Elastic 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 7.772Effective 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.

2B.11 Plate GirdersSections 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 SBLT should be used toidentify sections as rolled or welded; see the parameter list for more information.

If the plate girder has intermediate stiffeners, the spacing is set with the PNL parameter. These are then used to check against the code clauses ‘4.4.3.2 - Minimum web thickness forserviceability’ and ‘4.4.3.3 - Minimum web thickness to avoid compression flange buckling’. The following printout is then included if a TRACK 2.0 output is selected:

Shear Buckling check is required: Vb = 1070 kN : qw = 118N/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 - Simplifiedmethod’ and the result is included in the ratio checks.


2B.12 Composite SectionsSections that have been defined as acting compositely with a concrete flange either from astandard database section using the CM option, or from a modified user WIDE FLANGEdatabase with the additional composite parameters, cannot be designed with BS5950:2000.

2B.13 Design of Tapered BeamsSections will be checked as tapered members provided that are defined either as a Tapered Isection 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

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 the parameterUNL.

The program compares the resistance of members with the applied load effects, in accordancewith BS 5950-1:2000. Code checking is carried out for locations specified by the user via theSECTION command or the BEAM parameter. The results are presented in a form of a PASS/FAILidentifier and a RATIO of load effect to resistance for each member checked. The user maychoose the degree of detail in the output data by setting the TRACK parameter.

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

2B.13.1 Design Equations

A beam defined with tapered properties as defined above will be checked as a regular wideflange (e.g., UB or UC), except that the following is used in place of clause 4.3.6, the lateraltorsional buckling check.

90 — STAAD.Pro


2B.13.2 Check Moment for Taper Members as per clause G.2.2

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

Mxi ≤ Mbi (1 - Fc/Pc)

Where:

Fcis the longitudinal compression at the check location;

Mbi is the buckling resistance moment Mb from 4.3.6 for an equivalentslenderness λTB, see G.2.4.2, based on the appropriate modulus S, Seff, Z or Zeff ofthe cross-section at the point i considered;

Mxi is the moment about the major axis acting at the point i considered;

Pc is the compression resistance from 4.7.4 for a slenderness λTC .y, see G.2.3,based on the properties of the minimum depth of cross-section within thesegment length L

2B.13.3 G.2.3 Slenderness lTC

λTC = yλ

Where:

=

+

+ +y

a h

a h λ x

( )

( )

1 2 /

1 2 / 0.05( / )

0.5

s

s

2

2 2

λ = Ly/ryWhere:

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

hs is the distance between the shear centers of the flanges;

Ly is the length of the segment;

ry is the radius of gyration for buckling about the minor axis;

x is the torsional index

2B.13.4 G.2.4.2 Equivalent slenderness ITB for taperedmembers

λTB = cntνtλ

Where, for a two-flange haunch:

=

+ +

vta h

a h λ x( )

4 /

1 2 / 0.05( / )

0.5

s

s

2 2

Where:


C is the taper factor, see G.2.5;

2B.13.5 G.2.5 Taper factor

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

= +

− −

c 1 1x

D

D

3

9

2/3

max

min

Where:

Dmax is the maximum depth of cross-section within the length Ly, see FigureG.3;

Dmin is the minimum depth of cross-section within the length Ly, see FigureG.3;

x is the torsional index of the minimum depth cross-section, see 4.3.6.8

Otherwise, c is taken as 1.0 (unity).

92— STAAD.Pro


2C. British Codes - Design per BS5400STAAD.Pro is capable of performing steel design based on the British code BS 5400:Part 3:1982Steel, concrete and composite bridges Part 3. Code of practice for design of steel bridges andAmd No. 4051 and Amd No. 6488.

Design of members per BS 5400:Part 3:1982 requires the STAAD British Specialized DesignCodes SELECT Code Pack. It does not come as standard with British versions.

2C.1 General CommentsThe British Standard, BS5400 adopts the limit state design philosophy and is applicable tosteel, concrete, and composite construction. The code is in ten parts covering various aspects ofbridge design. The implementation of part 3, Code of practice for design of steel bridges, inSTAAD is restricted in its scope to simply supported spans. It is assumed that the depthremains constant and both construction and composite stages of steel I-Sections can bechecked. The following sections describe in more detail features of the design process currentlyavailable in STAAD.

2C.2 Shape LimitationsThe capacity of sections could be limited by local buckling if the ratio of flange outstand tothickness is large. In order to prevent this, the code sets limits to the ratio as per clause 9.3.2.In the event of exceeding these limits, the design process will terminate with reference to theclause.

2C.3 Section ClassSections are further defined as compact or noncompact. In the case of compact sections, thefull plastic moment capacity can be attained. In the case of noncompact sections, localbuckling of elements may occur prior to reaching the full moment capacity and for this reasonthe extreme fibre stresses are limited to first yield. In STAAD, section types are determined asper clause 9.3.7 and the checks that follow will relate to the type of section considered.

2C.4 Moment CapacityLateral torsional buckling may occur if a member has unrestrained elements in compression.The code deals with this effect by limiting the compressive stress to a value depending on theslenderness parameter which is a modified form of the ratio Le/Ry. Le is the effective lengthgoverned by the provision of lateral restraints satisfying the requirements of clause 9.12.1. Oncethe allowable compressive stress is determined then the moment capacity appropriate to thesection type can be calculated. 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 fullrestraint throughout, for the composite stage. The program then proceeds to calculate theallowable compressive stress based on appendix G7 from which the moment capacity is thendetermined.

2C.5 Shear CapacityThe shear capacity, as outlined in clause is a function of the limiting shear strength, l, which isdependant on the slenderness ratio. STAAD follows the iterative procedure of appendix G8 to


determine the limiting shear strength of the web panel. The shear capacity is then calculatedbased on the formula given under clause 9.9.2.2.

2C.6 Design ParametersAvailable design parameters to be used in conjunction with BS5400 are listed in table 2C.1.Depending on the value assigned to the WET parameter, you can determine the stage underconsideration. For a composite design check, taking into consideration the constructionstage, two separate analyses are required. In the first, member properties are non-compositeand the WET parameter is set to 1.0 . In the second, member properties should be changed tocomposite and the WET parameter set to 2.0. Member properties for composite or non-composite sections 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, comeunder WIDE FLANGE section-type and built-up sections under ISECTION. When specifyingcomposite properties the first parameter is assigned a negative value and four additionalparameters provided giving details of the concrete section. See user table examples provided.


ParameterName

DefaultValue

Description

ESTIFF 0 Specify the criteria used for the design ofcompression members with moments.

0. Member passes if either Cl. 4.8.3.3.1 or Cl.4.8.3.3.2 check.

1. Member passes if both Cl. 4.8.3.3.1 and Cl.4.8.3.3.2 check.

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

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

LY MemberLength

Length to calculate slenderness ratio for bendingabout Y-axis, in current units of length.

LZ MemberLength

Length to calculate slenderness ratio for bendingabout Z-axis, in current units of length.

Table 2C.1-BS5400 Design Parameters

94 — STAAD.Pro

2C. British Codes - Design per BS5400

ParameterName

DefaultValue

Description

MAIN 1.0 Grade of concrete:

1. 30 N/mm2

2. 40 N/mm2

3. 50 N/mm2

NSF 1.0 Net section factor for tension members.

PY * Yield stress of steel.

Set according to Design Strength of steel SGR

RATIO 1 Permissible ratio of actual to allowable stresses.

SBLT 0.0 Steel

0.0 = Rolled Section

1.0 = Built up Section

SGR 0.0 Steel Grade per BS4360

0. Grade 43

1. Grade 50

2. Grade 55

TRACK 1.0 Used to control the level of detail in the output

0. Suppress all member capacities

1. Print all member capacities

UNL MemberLength

Unsupported length for calculating allowablecompressive bending stress, in current units oflength.

WET 0.0 Used to specify the stage of construction.

0. Wet stage with no data saved forcomposite stage

1. Wet stage with data saved for compositestage

2. Composite and wet stage combined

3. Composite stage only


2C.7 Composite SectionsThe definition of composite sections has been provided for in the standard sections definition(refer to Section 5.20.1 of the Technical Reference Manual for details). This is purely foranalysis and for obtaining the right section properties. It uses the American requirement of 18times depth (CT) as the effective depth. For more control with British sections two newoptions are available in user provided tables.

2C.7.1 Wide Flange Composite

Using the standard definition of I sections in WIDE FLANGE, 4 additional values can now beprovided. The first is the width of concrete to the left of center of the steel web (b1). Thesecond is the concrete width to the right (b2). The third is the concrete depth (d1) to beconsidered. The last is the modular ratio. The above values are accepted in the program byadding a '-' at the first position on the first line of data. The program now awaits four extravalues on line 2 as described above. If (-) is provided on the second line the program requiresanother 2 breadths + 1 thickness for the bottom plate.

2C.7.2 I Section

The same is true for ISECTION definition in user table.

2C.7.3 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 and areavailable on request to any existing user. Please note however that composite design is notavailable in this portion of STAAD.

96— STAAD.Pro

2C. British Codes - Design per BS5400

2D. British Codes - Design per BS8007STAAD.Pro is capable of performing concrete design based on the British code BS8007:1987Design of concrete structures for retaining aqueous liquids. It is recommended that the designof the structure is carried out according to BS8110, unless modified by the recommendationsgiven in BS8007.

Design of members per BS8007:1987 requires the STAAD British Specialized Design CodesSELECT Code Pack. It does not come as standard with British versions.

The information in this section is to be used in conjunction with the BS8110. See "BritishCodes - Concrete Design per BS8110" on page 51

2D.1 Design ProcessThe design process is carried out in three stages.

1. Ultimate Limit States

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

2. Serviceability Limit States

In the second stage, flexural crack widths under serviceability load cases are calculated.The first and every other occurring design load case is considered as a serviceability loadcase and crack widths are calculated based on bar sizes and spacings proposed at theultimate limit state check.

Crack widths due to longitudinal and transverse moments are calculated directly underbars, midway between and at corners. A tabulated output indicating criticalserviceability load cases and moments for top and bottom of the slab is then produced.

3. Thermal crack widths

Finally thermal, crack width calculations are carried out. Through available parameters, theuser is able to provide information on the type of slab, temperature range and crack widthlimits.

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 crack widths arecalculated for the critical reinforcements and printed under each bar size.


Maximum bar spacing to limit crack widths to the user's limit is also printed under each barsize.

2D.2 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to BS8007.

These parameters not only act as a method to input required data for code calculations butgive the Engineer control over the actual design process. Default values of commonly usedvalues for conventional design practice have been chosen as the basis. Table 2D.1 contains acomplete list of available parameters with their default values.


ParameterName

DefaultValue

Description

FC 30N/mm2

Concrete grade, in current units of length andforce.

CLEAR 20 mm Distance from the outer surface to the edge ofthe bar, in current units of length. This isconsidered the same on both surfaces.

SRA 0.0 Orthogonal reinforcement layout withoutconsidering torsional moment Mxy - slabs on -500.orthogonal reinforcement layout with Mxy usedto calculate Wood & Armer moments for design.

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

SCON 1 Parameter which indicates the type of slab ee.ground or suspended as defined in BS8007

1 = Suspended Slab

2 = Ground Slab

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

CRACK * 0.2 mm Limiting thermal crack width, in current units oflength.

Table 2D.1-BS8007 Design Parameters

* Provided in current unit systems

98— STAAD.Pro

2D. British Codes - Design per BS8007

2D.3 Structural ModelStructural slabs that are to be designed to BS8007 must be modeled using finite elements.Refer to Section 1.6 of the Technical Reference Manual for information on the sign conventionused in the program for defining elements

It is recommended to connect elements in such a way that the positive local z axis pointsoutwards away, from the center of the container. In this manner the "Top" of elements willconsistently fall on the outer surface and internal pressure loads will act in the positivedirection 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 PROPERTIES command.The following example demonstrates the required input for a 300 mm slab modeled with tenelements.

UNIT MM

ELEMENT PROPERTIES

1 TO 10 THI 300.0

2D.4 Wood & Armer MomentsThis is controlled by the SRA parameter. If the default value of zero is used, the design will bebased on the Mx and My moments which are the direct results of STAAD analysis. The SRAparameter (Set Reinforcement Angle) can be manipulated to introduce Wood & Armermoments into the design replacing the pure Mx, My moments. These new design momentsallow the Mxy moment to be considered when designing the section. Orthogonal or skewreinforcement may be considered. SRA set to -500 will assume an orthogonal layout. Ifhowever a skew is to be considered, an angle is given in degrees, measured between the localelement x axis anti-clockwise (positive). The resulting Mx* and My* moments are calculatedand shown in the design format.


100 — STAAD.Pro

2E. British Codes - Design per British Cold Formed SteelCode

STAAD.Pro is capable of performing steel design based on the British code BS 5950-5:1998Structural use of steelwork in building - Part 5: Code of practice for design of cold formed thingauge sections . The program allows design of single (non-composite) members in tension,compression, bending, shear, as well as their combinations. Cold work of formingstrengthening effects have been included as an option.

Design of members per BS 5950-1:2000 requires the STAAD British Std Design CodesSELECT Code Pack.

2E.1 Cross-Sectional PropertiesThe user specifies the geometry of the cross-section by selecting one of the section shapedesignations from the Gross Section Property Tables published in the “The Steel ConstructionInstitute”, (Design of Structures using Cold Formed Steel Sections).

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 graphical userinterface (GUI) or by specifying the section designation symbol in the input file.

The properties listed in the tables are gross section properties. STAAD.Pro uses unreducedsection properties in the structure analysis stage. Both unreduced and effective sectionproperties are used in the design stage, as applicable.

2E.2 Design ProcedureThe following two design modes are available:

2E.2.1 Code Checking

The program compares the resistance of members with the applied load effects, in accordancewith BS 5950-5:1998. Code checking is carried out for locations specified by the user via theSECTION command or the BEAM parameter. The results are presented in a form of aPASS/FAIL identifier and a RATIO of load effect to resistance for each member checked. Theuser may choose the degree of detail in the output data by setting the TRACK parameter.



2E.2.2 Member Selection

The user may request that the program search the cold formed steel shapes database (BSstandard sections) for alternative members that pass the code check and meet the leastweight criterion. In addition, a minimum and/or maximum acceptable depth of the membermay be specified. The program will then evaluate all database sections of the type initiallyspecified (i.e., channel, angle, etc.) and, if a suitable replacement is found, presents designresults for that section. If no section satisfying the depth restrictions or lighter than theinitial one can be found, the program leaves the member unchanged, regardless of whether itpasses the code check or not.

Refer to Section 2.6 of the Technical Reference Manual for general information on MemberSelection. Refer to Section 5.48.3 of the Technical Reference Manual for details thespecification of the Member Selection command.

The program calculates effective section properties in accordance with Section 4 of the subjectcode. Cross-sectional properties and overall slenderness of members are checked forcompliance with:

l Clause 6.2.2, Maximum Effective Slenderness Ratio for members in Compression

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

2E.3 Design Equations

2E.3.1 Tensile Strength

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

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

Pt = AepyWhere:

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

py is the design strength

2E.3.2 Combined bending and tension

As per clause 7.3 of BS 5950-5:1998 members subjected to both axial tension and bendingshould be proportioned such that the following relationships are satisfied at the ultimatelimit state

Ft/Pt + Mz/Mcz + My/Mcy ≤ 1

Mz/Mcz ≤ 1

and

My/Mcy ≤ 1

Where

102— STAAD.Pro

2E. British Codes - Design per British Cold Formed Steel Code

Ftis the applies tensile strength

Ptis the tensile capacity determined in accordance with clause 7.2.1 of the subjectcode

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

2E.3.3 Compressive Strength

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

For sections symmetrical about both principal axes or closed cross-sections which are notsubjected to torsional flexural buckling, the buckling resistance under axial load, Pc, may beobtained from the following equation as per clause 6.2.3 of the subject code

=+ −

PcP P

ϕ ϕ P P

E cs

E cs2

For Sections symmetrical about a single axis and which are not subject to torsional flexuralbuckling, the buckling resistance under axial load, Pc, may be obtained from the followingequation as per clause 6.2.4 of the subject code

′ =+

P c

M P

M P e( )c c

c c s

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

2E.3.4 Torsional flexural buckling

Design of the members which have at least one axis of symmetry, and which are subject totorsional flexural buckling should be done according to the stipulations of the clause 6.3.2using factored slenderness ratio αLE/r in place of actual slenderness ratio while reading Table10 for the value of Compressive strength(pc).

Where:

α = (PE/PTF) when PE > PTFα = 1, otherwise

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

2E.3.5 Combined bending and compression

Members subjected to both axial compression and bending should be checked for localcapacity and overall buckling

Local capacity check as per clause 6.4.2 of the subject code

Fc/Pcs + Mz/Mcz + My/Mcy ≤ 1


2E.3.6 Overall buckling check as per clause 6.4.3 of thesubject code

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

+ + ≤

−

−

1F

P

M

C M

M

C M1 1

c

c

z

bx czFc

PEz

y

by cyFc

PEy

For Beams subjected to lateral buckling, the following relationship should be satisfied

+ + ≤

−

1F

P

M

M

M

C M 1

c

c

z

b

y

by cyFc

PEy

Fcis the applied axial load

Pcs is the short strut capacity as per clause 6.2.3

Mz is 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 ofFc and My, as per clause 5.2.2 and 5.6

Mcyis the moment capacity in bending about the local Y axis, in the absence ofFc and Mz,as per clause 5.2.2 and 5.6

M-b is the lateral buckling resistance moment as per clause 5.6.2

PEzis the flexural buckling load in compression for bending about the local Zaxis

PEyis the flexural buckling load in compression for bending about the local Yaxis

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

Mcz, Mcy, and Mb are calculated from clause numbers 5.2.2 and 5.6 in the manner describedherein below.

2E.3.7 Calculation of moment capacities

For restrained beams, the applied moment based on factored loads should not be greater thenthe bending moment resistance of the section, Mc

Mcz = Szz x poMcy = Syyx po

=

−

p p1.13 0.0019o

D

t

Y

y280

w s

Where

104 — STAAD.Pro


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 shouldnot greater then design strength py

For unrestrained beams the applied moment based on factored loads should not be greaterthan the smaller of the bending moment resistance of the section , Mc , and the bucklingresistance moment of the beam, Mb

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

= ≤+ −

M Mb

M M

ϕ ϕ M Mc

E y

B B E y2

φB = [My + (1 + η)ME]/2

MY is the yield moment of the section , product of design strength py and elasticmodules of the gross section with respect to the compression flange Zc

ME is the elastic lateral buckling resistance as per clause 5.6.2.2

η is the Perry coefficient

Please refer clause numbers 5.2.2 and 5.6 of the subject code for a detailed discussion regardingthe parameters used in the abovementioned equations.

2E.3.8 Shear Strength

The maximum shear stress should not be greater then 0.7 × py as per clause 5.4.2

The average shear stress should not exceed the lesser of the shear yield strength, pv or the shearbuckling strength, qcr as stipulated in clause 5.4.3 of the subject code.

The parameters are calculated as follows :

pv = 0.6·pyqcr = (1000·t/D)2 N/mm2

Pv = A·min(pv, qcr)

Where:

Pv is 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

2E.3.9 Combined bending and Shear

For beam webs subjected to both bending and shear stresses the member should be designed


to satisfy the following relationship as per the stipulations of clause 5.5.2 of the subject code

(Fv/Pv)2 + (M/Mc)

2 ≤ 1

Where:

Fv is the shear force

M is the bending moment acting at the same section as FvMcis the moment capacity determined in accordance with 5.2.2

2E.4 Design ParametersThe design parameters outlined in Table 2E.1 are used to control the design procedure. Theseparameters communicate design decisions from the engineer to the program and thus allowthe engineer to control the design process to suit an application's specific needs.

The default parameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements, some or all ofthese parameter values may be changed to exactly model the physical structure.



CODE BS5950 COLD Design Code to follow.


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

106— STAAD.Pro



BEAM 1.0 When this parameter is setto 1.0 (default), theadequacy of the member isdetermined by checking atotal of 13 equally spacedlocations along the lengthof the member. If theBEAM value 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 Cb. SeeBS:5950-5:1998,5.6. Usedfor Combined axial loadand bending design.

CMY 1.0 Coefficient of equivalentuniform bending Cb. SeeBS:5950-5:1998,5.6. Usedfor Combined axial loadand bending design.

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

0 – effectshould notbe included

1 – effectshould beincluded



FLX 1 Specifies whethertorsional-flexural bucklingrestraint is provided or isnot necessary for themember. See BS:5950-5:1998, 5.6

Values:

0 – Sectionsubject totorsionalflexuralbuckling

1 – Sectionnot subjectto torsionalflexuralbuckling

FU 430 MPa Ultimate tensile strengthof steel in current units.

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 from 0.01(for a column completelyprevented from buckling)to any user specified largevalue. It is used tocompute the KL/R ratiofor twisting fordetermining the capacityin axial compression.

108— STAAD.Pro



KY 1.0 Effective length factor foroverall buckling about thelocal Y-axis. It is a fractionand is unit-less. Valuescan range from 0.01 (for acolumn completelyprevented from buckling)to any user specified largevalue. It is used tocompute the KL/R ratiofor determining thecapacity in axialcompression.

KZ 1.0 Effective length factor foroverall buckling in thelocal Z-axis. It is a fractionand is unit-less. Valuescan range from 0.01 (for amember completelyprevented from buckling)to any user 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 from 0.01(for a member completelyprevented from torsionalbuckling) to any userspecified large value. It isused to compute the KL/Rratio for twisting fordetermining the capacityin axial compression.



LY Member length Effective length for overallbuckling in the local Y-axis. It is input in thecurrent units of length.Values can range from 0.01(for a member completelyprevented from buckling)to any user specified largevalue. It is used tocompute the KL/R ratiofor determining thecapacity in axialcompression.

LZ Member length Effective length for overallbuckling in the local Z-axis. It is input in thecurrent units of length.Values can range from 0.01(for a member completelyprevented from buckling)to any user specified largevalue. It is used tocompute the KL/R ratiofor determining thecapacity in axialcompression.

110 — STAAD.Pro



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 of actualto allowable stresses



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

0 - Printsonly themembernumber,sectionname, ratio,andPASS/FAILstatus.

1 - Prints thedesignsummary inaddition tothat printedby TRACK 1

2 - Printsmember andmaterialproperties inaddition tothat printedby TRACK 2.

2E.5 Verification ProblemShown below is a verification example for reference purposes.

In this problem, we have assigned Channel sections with lips to different members. Membernumbers 28 to 31 have been assigned section 230CLHS66X16,member numbers 3 TO 6 and 15TO 19 have been assigned the section 230CLMIL70X30 and member numbers 1, 2, 7 TO 14have been assigned the section 170CLHS56X18. These members have been designed as per BS5950 Part 5. Other sections have been assigned from the AISI shapes database (Americancold-formed steel) and designed in accordance with that code.

112— STAAD.Pro


2E.5.1 Solution

A. 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

=

−

p p1.13 0.0019o

D

t

Y

y280

w s

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 = Szz·po = 27,632.4(332.727) = 9.19(10)6 N·mm

Mcy = Syy·po = 27,632.4(5,427.50) = 3.46(10)6 N·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

Bending Ratio Y = 19755.3 / 3.46 X106 = 0.0057

Biaxial Bending ratio = 0.235 + 0.0057 = 0.2407

Buckling resistance moment Mb

As per section 5.6.2, the buckling resistance moment

= ≤+ −

M Mb

M M

ϕ ϕ M Mc

E y

B B E y2

Where:

The Yield moment of section is given by

MY = Szz · po = 9.19(10)6 N·mm

The elastic buckling resistance moment as per clause 5.6.2.2 is calculated to be

ME = 4.649(10)6 N·mm

And

φB = [My + (1 + η)ME]/2

So that

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

Which yields


= = ⋅⋅

+

− ⋅

M N mm9.98(10)b

4.649(10) 9.19(10)

2.325(10) 2.325(10) 4.649(10) 9.19(10)

66 6

10 102

6 6

B. 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)PE]/2 = 683,512.45 N

Buckling resistance

= =+ −

P N153, 782cP P

ϕ ϕ P P

E cs

E cs2

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

′ =+

P c

M P

M P e( )c c

c c s

Where:

The limiting compressive moment, Mc, in the relevant direction is equal to 9.19(10)6

N·mm,as calculated above

And the distance, es, of the geometric neutral axis of the gross cross section and that ofthe effective cross section is equal to 38.24 m

So that,

′ = =⋅ +

P N93, 788.7c

( )9.19(10) 153, 782

9.19(10) 153, 782 38.24

6

6

Compression ratio = 3,436.75/93,788.7 = 0.0366

C. Axial Compression and Bending

+ + ≤

−

1F

P

M

M

M

C M 1

c

c

z

b

y

by cyFc

PEy

3,436.75/93,788.7 + 2.15(10)6/(9.98(10)6 ) + 19,755.3/[1.0 * 3.46(10)6(1 - 3,436.75/1.185(10)6 )]= 0.2578

Local capacity check as per clause 6.4.2

+ + = + + = 0.2647F

P

M

M

M

M

3, 436.75

457.698(379.212)

2.15(10)

9.19(10)

19, 755.3

1.81(10)

c

cs

z

cz

y

cy

6

6 6

114 — STAAD.Pro


Overall buckling check per 6.4.3

+ + ≤

−

−

1F

P

M

C M

M

C M1 1

c

c

z

bx czFc

PEz

y

by cyFc

PEy

= 0.2773

D. Shear Check as per clause 5.4.2 and 5.4.3

pv = 0.6·py = 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(pv, qcr)

Shear resistance Y = 33,579.4 N

Shear resistance Z = 21,148.6 N

Shear Ratio Y = 5,627.72/33,579.4 = 0.1675

Shear Ratio Z = 5,627.72/21,148.6 = 0.0031

E. Shear Check with Bending as per clause 5.5.2

Shear with bending on Z

(Fv/Pv)2 + (Mz/Mcz)

2 = (5,627.72/33,579.4)2 + [2.15·106 /(9.19·106 )]2 = 0.08327

Shear with bending on Y

(Fv/Pv)2 + (My/Mcy)

2 = (67.114/21,148.6)2 + [19,755.3/(3.46·106 )]2 = 0.000043

2E.5.2 Comparison

Criteria STAAD.Pro ResultHand

CalculationDifference

Axial compression ratio 0.037 0.0366 none

Axial compression andbending interactionratio (overall buckling)

0.278 0.2773 none

Bending Z ratio 0.236 0.235 none

Bending Y ratio 0.006 0.0057 none

Biaxial bending ratio 0.2407 0.241 none

Shear Z ratio 0.168 0.1675 none

Shear Y ratio 0.003 0.0031 none

Table 2E.2-Comparison for verification problem


Criteria STAAD.Pro ResultHand

CalculationDifference

Bending Z and Shear Yinteraction ratio

0.084 0.08327 none

Bending Y and Shear Zinteraction ratio

0.000 0.000043 none

2E.5.3 Input File

STAAD SPACE

SET ECHO OFF

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 52; 8 0 5 4;

9 0 5 6; 10 0 5 8; 11 10 5 2; 12 10 5 4; 13 10 5 6; 14 10 5 8; 155 5 2;

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 0 0;

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 1617; 18 17 18;

19 18 6; 20 7 15; 21 15 11; 22 8 16; 23 16 12; 24 9 17; 25 17 13;26 10 18;

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

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

MEMBER PROPERTY COLDFORMED AMERICAN

32 TO 39 TABLE ST 3LU3X060

20 TO 27 TABLE ST 3HU3X075

MEMBER PROPERTY COLDFORMED 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

116— STAAD.Pro


DEFINE MATERIAL START

ISOTROPIC STEEL

E 4.176E+006

POISSON 0.3

DENSITY 0.489024

ALPHA 6.5E-006

DAMP 0.03

END DEFINE MATERIAL

CONSTANTS

BETA 90 MEMB 20 TO 27

MATERIAL STEEL MEMB 1 TO 39

MEMBER TENSION

32 TO 39

UNIT FEET KIP

LOAD 1 VERTICAL AND HORIZONTAL

MEMBER LOAD

3 TO 6 20 TO 27 UNI GY -0.3 0 5

JOINT LOAD

1 2 FX 0.6

2 4 FZ -0.6

PERFORM ANALYSIS 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

CWY 1 ALL

BEAM 1 ALL

TRACK 2 ALL

CHECK CODE MEMB 20 21

PARAMETER 2

CODE BS5950 COLD

TRACK 2 MEMB 1 TO 19 28 TO 31

CHECK CODE MEMB 1 2

FINISH


2E.5.4 Output

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: 609.60 LOCATION: 609.60|| STATUS: PASS RATIO = 0.278 GOV.MODE: 6.4-Bend + Compress 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): 4.58

z-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 axis

Compression Capacity (Pc) : 93.70Moment Capacity (Mc) : 9.17 3.47Shear Capacity (Pv) : 21.00 33.50

LTB Capacity (Mb) : 9.17

EACH CLAUSE CHECK UNDER CRITICAL LOAD :

CLAUSE COMBINATION RATIOBS-6.3 Compression ratio - Axial 0.037

BS-6.4 Bend-Compression ratio 0.278

BS-5.1 Bending Ratio - Z 0.236

BS-5.1 Bending Ratio - Y 0.006

BS-5.1 Biaxial Bending Ratio 0.241

BS-5.4 Shear Ratio - Z 0.168

BS-5.4 Shear Ratio - Y 0.003

BS-5.5.2 Bending -Z & Shear - Y Ratio 0.084

BS-5.5.2 Bending -Y & Shear - Z Ratio 0.000

Torsion and deflections have not been considered in the design.

118— STAAD.Pro


Section 3

Canadian Codes


120 — STAAD.Pro

3A. Canadian Codes - Concrete Design per CSA StandardA23.3-94

STAAD.Pro is capable of performing concrete design based on the Candadian code CSA A23.31994 Design of Concrete Structures. Given the width and depth (or diameter for circularcolumns) of a section, the program will calculate the required reinforcement to resist theforces and moments.

Design of members per CSA A23.3 1994 requires the STAAD CAN/AUS/SA Design CodesSELECT Code Pack.


l For Beams - Prismatic (Rectangular, Square & Tee)

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

l For Slabs - 4-noded Plate Elements


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 and 300mm width)and the second set of members, with only depth and no width provided, will be assumed to becircular with a 300mm diameter

3A.3 Slenderness Effects and Analysis ConsiderationsSTAAD provides the user with two methods of accounting for the slenderness effect in theanalysis and design of concrete members. The first method is equivalent to the procedurepresented in CSA STANDARD A23.3-94 Clause 10.13. STAAD accounts for the secondarymoments, due to axial loads and deflections, when the PDELTA ANALYSIS command is used.After solving for the joint displacements of the structure, the program calculates theadditional moments induced in the structure due to the P-Delta effect. Therefore, byperforming a P-Delta analysis, member forces are calculated which will require no usermodification before beginning member design. Refer to Section 5.37.2 of the TechnicalReference Manual for additional details on this analysis facility.

The second method by which STAAD allows the user to account for the slenderness effect isthrough user supplied moment magnification factors (see the parameter MMAG in Table 3A.1).Here the user approximates the additional moment by supplying a factor by which moments


will be multiplied before beginning member design. This second procedure allowsslenderness to be considered in accordance with Clause 10.14 of the code.

Note: STAAD does not factor loads automatically for concrete design. All the properfactored loads must be provided by the user before the ANALYSIS specification.

While performing a P-Delta analysis, all load cases must be defined as primary load cases. Ifthe effects of separate load cases are to be combined, it should be done either by using theREPEAT LOAD command or by specifying the load information of these individual loadingcases under one single load case. Usage of the LOAD COMBINATION command will yieldincorrect results for P-Delta Analysis in STAAD.Pro.

3A.4 Design ParametersThe program contains a number of parameters which are needed to perform design per CSASTANDARD A23.3-94. 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,which are commonly used numbers in conventional design practice, have been used forsimplicity. Table 3A.1 contains a list of available parameters and their default values. It isnecessary to declare length and force units as Millimeter and Newton before performing theconcrete design.


Param-eterName

DefaultValue

Description

CLB 40mm Clear cover to reinforcing bar at bottom of crosssection.

CLS 40mm Clear cover to reinforcing bar along the side ofthe cross section.

CLT 40mm Clear cover to reinforcing bar at top of crosssection.

DEPTH YD Depth of the concrete member. This valuedefaults to YD as provided under MEMBERPROPERTIES.

Table 3A.1-Canadian Concrete Design CSA-A23.3-94 Parameters

122— STAAD.Pro

3A. Canadian Codes - Concrete Design per CSA Standard A23.3-94

Param-eterName

DefaultValue

Description

EFACE 0.0 Faceof

Support

Distance of face of support from end node ofbeam. Used for shear and torsion calculation.


FC 30N/mm2

Specified compressive strength of concrete.

FYMAIN 400N/m-m2

Yield Stress for main reinforcing steel.

FYSEC 400N/mm2

Yield Stress for secondary reinforcing steel.

MAXMAIN

Number55 bar

Maximum main reinforcement bar size.

MINMAIN

Number10 bar

Minimum main reinforcement bar size

MINSEC Number10 bar

Minimum secondary (stirrup) reinforcementbar size.

MMAG 1.0 A factor by which the column design momentswill be magnified.

NSECTION

12 Number of equally-spaced sections to beconsidered in finding critical moments forbeam design.

REINF 0.0 Tied Column. A value of 1.0 will mean spiral.

SFACE 0.0 Distance of face of support from start node ofbeam. Used for shear and torsion calculation.


TRACK 0.0 0. Critical Moment will not be printed outwith beam design report.

1. Moments will be printed.


Param-eterName

DefaultValue

Description

WIDTH ZD Width of the concrete member. This valuedefaults to ZD as provided under MEMBERPROPERTIES.

3A.5 Beam DesignBeams are designed for flexure, shear and torsion. For all these forces, all active beam loadingsare scanned to create moment and shear envelopes, and locate critical sections. The totalnumber of sections considered is thirteen (start, end, and 11 intermediate), unless thatnumber is redefined with the NSECTION parameter.


Design for flexure is performed per the rules of Chapter 10 of CSA Standard A23.3-94.Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging(creating tensile stress at the top face) moments are calculated for all active load cases at eachof the thirteen sections. Each of these sections are designed to resist the critical sagging andhogging moments. Currently, design of singly reinforced sections only is permitted. If thesection dimensions are inadequate as a singly reinforced section, such a message will beprinted in the 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 layer ofassumed reinforcement and reinforcement requirements are calculated. After the preliminarydesign, reinforcing bars are chosen from the internal database in single or multiple layers. Theentire flexure design is performed again in a second pass taking into account the changedeffective depths of sections calculated on the basis of reinforcement provided after thepreliminary design. Final provision of flexural reinforcements are made then. Efforts havebeen made to meet the guideline for the curtailment of reinforcements as per CSA StandardA23.3-94. Although exact curtailment lengths are not mentioned explicitly in the designoutput (which finally will be more or less guided by the detailer taking into account otherpractical considerations), the user has the choice of printing reinforcements provided bySTAAD at 13 equally spaced sections from which the final detailed drawing can be prepared.

The following annotations apply to the output for Beam Design.

LEVELSerial number of bar level which may contain one or more bar group.

HEIGHTHeight of bar level from the bottom of beam.

BAR INFOrmationReinforcement bar information specifying number of bars and size.

FROMDistance from the start of the beam to the start of the rebar.

124 — STAAD.Pro


TODistance from the start of the beam to the end of the rebar.

ANCHOR(STA,END)

States whether anchorage, either a hook or continuation, is needed at start (STA) orat the end (END) of the bar.

3A.5.2 Design for Shear and Torsion

Design for shear and torsion is performed per the rules of Chapter 11 of CSA Standard A23.3-94.Shear reinforcement is calculated to resist both shear forces and torsional moments. Sheardesign is performed at the start and end sections. The location along the member span fordesign is chosen as the effective depth + SFACE at the start, and effective depth + EFACE atthe end. The load case which gives rise to the highest stirrup area for shear & torsion is chosenas the critical 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 closed hoops forbeams subjected to torsion.

3A.5.3 Example of Input

Example of Input Data for Beam Design

UNIT NEWTON MMS


CODE CANADA

FYMAIN 415 ALL

FYSEC 415 ALL

FC 35 ALL




DESIGN BEAM 2 TO 9

END CONCRETE DESIGN

3A.6 Column DesignColumn design is performed per the rules of Chapters 7 & 8 of the CSA Standard A23.3-94.Columns are designed for axial force and biaxial moments at the ends. All active loadings aretested to calculate reinforcement. The loading which produces maximum reinforcement iscalled the critical load. Column design is done for square, rectangular and circular sections.For rectangular and square sections, the reinforcement is always assumed to be equallydistributed on each side. That means the total number of bars will always be a multiple of four(4). This may cause slightly conservative results in some cases.

Example of Input Data for Column Design


UNIT NEWTON MMS


CODE CANADIAN

FYMAIN 415 ALL

FC 35 ALL




END CONCRETE DESIGN

3A.7 Slab/Wall DesignTo design a slab or wall, it must be modeled using finite elements. The commands forspecifying elements are in accordance with the relevant sections of the Technical ReferenceManual.

Elements are designed for the moments Mx and My using the same principles as those forbeams in flexure. The width of the beam is assumed to be unity for this purpose. Thesemoments are obtained from the element force output (see Section 3.8 of the TechnicalReference Manual). The reinforcement required to resist Mx moment is denoted aslongitudinal reinforcement and the reinforcement required to resist My moment is denotedas transverse reinforcement. The effective depth is calculated assuming #10 bars are provided.The parameters FYMAIN, FC, CLT, and CLB listed in Table 3A.1 are relevant to slab design.Other parameters mentioned in Table 3A.1 are not applicable to slab design. The outputconsists only of area of steel required. Actual bar arrangement is not calculated because anelement most likely represents just a fraction of the total slab area.


Example of Input Data for Slab/Wall Design

UNIT NEWTON MMS

126— STAAD.Pro



CODE CANADA

FYMAIN 415 ALL

FC 35 ALL

CLB 40 ALL


END CONCRETE DESIGN


128— STAAD.Pro

3B. Canadian Codes - Steel Design per CSA StandardCAN/CSA-S16-01

STAAD.Pro is capable of performing steel design based on the Canadian code CAN/CSA-S16-01Limit States Design of Steel Structures.

Design of members per CAN/CSA-S16-01 requires the STAAD CAN/AUS/SA Design CodesSELECT Code Pack.

3B.1 General CommentsThe design of structural steel members in accordance with the specification CAN/CSA S16-01Limit States Design of Steel Structures is can be used in STAAD.Pro. This code supercedes theprevious edition of the code CAN/CSA – S16.1-94.

The design philosophy embodied in this specification is based on the concept of limit statedesign. Structures are designed and proportioned taking into consideration the limit states atwhich they would become unfit for their intended use. Two major categories of limit-statesare recognized - ultimate and serviceability. The primary considerations in ultimate limit statedesign are strength and stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all steel structures undervarious loading conditions and at the same time the probability of limits being surpassed isacceptably low.

In the STAAD.Pro implementation, members are proportioned to resist the design loadswithout exceeding the limit states of strength, stability and serviceability. Accordingly, themost economic section is selected on the basis of the least weight criteria as augmented by thedesigner in specification of allowable member depths, desired section type, or other suchparameters. The code checking portion of the program checks whether code requirements foreach selected section are met and identifies the governing criteria.

The following sections describe the salient features of the STAAD.Pro implementation ofCAN/CSA-S16-01. A detailed description of the design process along with its underlyingconcepts and assumptions is available in the specification document.

3B.2 Analysis MethodologyThe elastic analysis method is used to obtain the forces and moments for design. Analysis isdone for the specified primary and combination loading condition. You are allowed completeflexibility in providing loading specifications and using appropriate load factors to createnecessary loading situations. Depending upon the analysis requirements, regular stiffnessanalysis or P-Delta analysis may be specified. Dynamic analysis may also be performed and theresults combined with static analysis results.

3B.3 Member Property SpecificationsFor specification of member properties, the steel section library available in STAAD.Pro may beused. The next section describes the syntax of commands used to assign properties from thebuilt-in steel table. Member properties may also be specified using the User Table facility. Formore information on these facilities, refer to the STAAD.Pro Technical Reference Manual.


3B.4 Built-in Steel Section LibraryThe following information is provided for use when the built-in steel tables are to bereferenced for member property specification. These properties are stored in a database file. Ifcalled for, the properties are also used for member design. Since the shear areas are built intothese tables, shear deformation is always considered during the analysis of these members.

Almost all Canadian steel sections are available for input. A complete listing of the sectionsavailable in the built-in steel section library may be obtained by using the tools of thegraphical user interface.

Following is the description of the different types of sections available:

3B.4.1 Welded Wide Flanges (WW shapes)

Welded wide flange shapes listed in the CSA steel tables can be designated using the samescheme used by CSA. The following example illustrates the specification of welded wideflange shapes.

100 TO 150 TA ST WW400X444

34 35 TA ST WW900X347

3B.4.2 Wide Flanges (W shapes)

Designation of wide flanges in STAAD is the same as that in CSA tables. For example,

10 TO 75 95 TO 105 TA ST W460X106

100 TO 200 TA ST W610X101

3B.4.3 S, M, HP shapes

In addition to welded wide flanges and regular wide flanges, other I shaped sections like S, Mand HP shapes are also available. The designation scheme is identical to that listed in theCSA tables. While specifying the sections, it should be remembered that the portion after thedecimal point should be omitted. Thus, M310X17.6 should be specified as M310X17 andS180X22.8 should be specified as S180X22. Examples illustrating specifications of these shapesare provided below.

10 TO 20 BY 2 TA ST S510X98

45 TO 55 TA ST M150X6

88 90 96 TA ST HP310X79

3B.4.4 Channel Sections (C & MC shapes)

C and MC shapes are designated as shown in the following example. As in S, M and HPsections, the portion after the decimal point must be omitted in section designations. Thus,MC250X42.4 should be designated as MC250X42.

130 — STAAD.Pro

3B. Canadian Codes - Steel Design per CSA Standard CAN/CSA-S16-01

55 TO 90 TA ST C250X30

30 TO 45 TA ST MC200X33


Back-to-back double channels, with or without spacing between them, are specified bypreceding the section designation by the letter D. For example, a back-to-back double channelsection C200X28 without any spacing in between should be specified 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

Note that the specification SP after the section designation is used for providing the spacing.The spacing should always be provided in the current length unit.

3B.4.6 Angles

To specify angles, the angle name is preceded by the letter L. Thus, a 200X200 angle with a25mm thickness is designated as L200X200X25. The following examples illustrate anglespecifications.

75 TO 95 TA ST L100X100X8

33 34 35 TA ST L200X100X20

Note that the above specification is for “standard” angles. In this specification, the local z-axis(see Fig. 2.6 in the Technical Reference Manual) corresponds to the Y’-Y’ axis shown in theCSA table. Another common practice of specifying angles assumes the local y-axis tocorrespond to the Y’-Y’ axis. To specify angles in accordance with this convention, the reverseangle designation facility has been provided. A reverse angle may be specified by substitutingthe word ST with the word 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 of the STAADTechnical Reference manual.


To specify double angles, the specification ST should be substituted with LD (for long legback-to-back) or SD (short leg back-to-back). For equal angles, either SD or LD will serve thepurpose. Spacing between angles may be provided by using the word SP followed by the valueof spacing (in current length unit) after section designation.

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 of 125X75X6 angleswith a spacing of 2.5 length units.

3B.4.8 Tees

Tee sections obtained by cutting W sections may be specified by using the T specificationinstead 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.

3B.4.9 Rectangular Hollow Sections

These sections may be specified in two possible ways. Those sections listed in the CSA tablesmay 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(for width),and TH(for thickness) specifications.

For example:

100 TO 200 TA ST TUBE DT 8.0 WT 6.0 TH 0.5

will describe a tube with a depth of 8 in., width of 6 in. and a wall thickness of 0.5 inches.Note that the values of depth, width and thickness must be provided in current length unit.

3B.4.10 Circular Hollow Sections

Sections listed in the CSA tables may be provided as follows:

15 TO 25 TA ST PIP33X2.5

132— STAAD.Pro


In addition to sections listed in the CSA tables, circular hollow sections may be specified byusing the OD (outside diameter) and ID (inside diameter) specifications. For example:


will describe a pipe with an outside diameter of 10 length units and inside diameter of 9.0length units. Note that the values of outside and inside diameters must be provided in termsof 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

* WW SHAPES

2 TA ST WW700X185

* S SHAPES

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 TO BACK

11 TA LD L100X90X6 SP 2.0

* DOUBLE ANGLES, SHORT LEG BACK TO BACK

12 TA SD L125X75X6 SP 2.5

* TUBES

13 TA ST TUB120807

* TUBES


* PIPES

15 TA ST PIP273X6.3

* PIPES


PRINT MEMBER PROPERTIES

FINISH

3B.5 Section ClassificationThe CSA specification allows inelastic deformation of section elements. Thus, local bucklingbecomes an important criterion. Steel sections are classified as plastic (Class 1), compact (Class2), noncompact (Class 3), or slender element (Class 4) sections depending upon their localbuckling characteristics (See Clause 11.2 and Table 1 of CAN/CSA-S16-01). This classification isa function of the geometric properties of the section. The design procedures are differentdepending on the section class. STAAD.Pro determines the section classification for thestandard shapes and user specified shapes.

Note: The design of Class 4 sections requires STAAD.Pro V8i (SELECTseries 2) build2007.07 or higher. Otherwise, design is performed for sections that fall into thecategory of Class 1,2 or 3 sections only.

3B.6 Member ResistancesThe member resistances are calculated in STAAD.Pro according to the procedures outlined insection 13 of the specification. These depend on several factors such as members unsupportedlengths, cross-sectional properties, slenderness factors, unsupported width to thickness ratiosand so on. Note that the program automatically takes into consideration appropriateresistance factors to calculate member resistances. Explained here is the procedure adopted inSTAAD.Pro for calculating the member resistances.

134 — STAAD.Pro


Note: The design of Class 4 sections requires STAAD.Pro V8i (SELECTseries 2) build2007.07 or higher.

3B.6.1 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.

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 consideringeffective yield stress.

= Resistance factor


3B.6.2 Members Subject to Axial Forces

Axial Tension

The criteria governing the capacity of tension members is based on two limit states. The limitstate of yielding in the gross section is intended to prevent excessive elongation of themember. The second limit state involves fracture at the section with the minimum effectivenet area. The net section area may be specified by the user through the use of the parameterNSF (see Table 3B.1). STAAD calculates the tension capacity of a member based on these twolimits states per Cl.13.2 of CAN/CSA-S16-01. Parameters FYLD, FU, and NSF are applicable forthese calculations.

Axial Compression

The compressive resistance of columns is determined based on Clause 13.3 of the code. Theequations presented in this section of the code assume that the compressive resistance is afunction of the compressive strength of the gross section (Gross section Area times the YieldStrength) as well as the slenderness factor (KL/r ratios). The effective length for thecalculation of compression resistance 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 axialcompression capacity in general column flexural buckling is calculated from Cl.13.3.1using the slenderness ratios for the local Y-Y and Z-Z axis. The parameters KY, LY, KZand LZ are applicable for this.

2. For single angles, which are frame members not subjected to any bending or trussmembers, the axial compression capacity in general column flexural buckling and localbuckling of thin legs is calculated using the rules of the AISC - LRFD code, 2nd ed.,1994. The reason for this is that the Canadian code doesn’t provide any clear guidelinesfor calculating this value. The parameters KY, LY, KZ, and LZ are applicable for this.

3. The axial compression capacity is also calculated by taking flexural-torsional bucklinginto account. The rules of Appendix D, page 1-109 of CAN/CSA-S16-01are used for thispurpose. Parameters KT and LT may be used to provide the effective length factor andeffective length value for flexural-torsional buckling. Flexural-torsional bucklingcapacity is computed for single 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 1.34 for all othershapes.

5. While computing the general column flexural buckling capacity of sections with axialcompression + bending, the special provisions of 13.8.1(a), 13.8.1(b) and 13.8.1(c) areapplied. 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 compressive resistance shouldbe determined by either of the following equations.

136— STAAD.Pro


a. Cr= ϕAe Fy (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 different sectionshapes are as follows.

l For flanges of I-section, T-section and channel section and legs of angle section

be= 200t/√(Fy )

l For stem of T-section

be= 340t/√(Fy )

l For flanges of HSS rectangular or Tube sections

be= 670t/√((Fy )

l For circular HSS or Pipe section

D= 23000t/(Fyb. Cr= ϕAFye (1+λye

2n )-1⁄n

Where:

n = 1.34

λye = √(Fye/F_e )

Fe=(π2 E)/(KL/r)2

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 shaped section.

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)


3B.6.3 Members Subject to Bending

The laterally unsupported length of the compression flange for the purpose of computing thefactored moment resistance is specified in STAAD with the help of the parameter UNL. IfUNL is less than one tenth the member length (member length is the distance between thejoints of the member), the member is treated as being continuously laterally supported. Inthis case, the moment resistance is computed from Clause 13.5 of the code. If UNL is greaterthan or equal to one tenth the member length, its value is used as the laterally unsupportedlength. The equations 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 capacity calculationsare :

1. The weak axis bending capacity of all sections except single angles is calculated as

For Class 1 & 2 sections, φ·Py · FyFor Class 3 sections, φ · Sy · Fywhere

φ = 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. For single angles, the bending capacities are calculated for the principal axes. Thespecifications of Section 5, page 6-283 of AISC-LRFD 1994, 2nd ed., are used for thispurpose because the Canadian code doesn’t provide any clear guidelines for calculatingthis value.

3. For calculating the bending capacity about the Z-Z axis of singly symmetric shapessuch as Tees and Double angles, CAN/CSA-S16-01 stipulates in Clause 13.6(d), page 1-31,that a rational method, such as that given in SSRC’s Guide to Stability Design Criteriaof Metal Structures, be used. Instead, STAAD uses the rules of Section 2c, page 6-55 ofAISC-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 sections, themember should be considered as failed and an error message will be thrown.

ii. When flanges meet the requirements of Class 3 but web exceeds the limits for Class 3,resisting moment shall be determined by the following equation.

′ =

−

−

M M 1 0.0005r r

A

A

h

w M ϕ

1, 900

/

w

f f s

138— STAAD.Pro


Where Mr = factored moment resistance as determined by Clause 13.5 or 13.6 but not toexceed My = factored moment resistance for Class 3 sections = My

If axial compressive force is present in addition to the moment, modified momentresistance should be as follows.

′ =

−

−

−M M 1 0.0005 1,900r r

A

A

h

w

C ϕC

M ϕ

( )1 0.65 /

/

w

f

f y

f s

Cy = A · FyS = Elastic section modulus of steel section.

iii. For sections whose webs meet the requirements of Class 3 and whose flanges exceed thelimit of Class 3, the moment resistance shall be calculated as

Mr = ϕ · Se · FyWhere:

Se = effective section modulus determined using effective flange width.

l For Rectangular HSS section, effective flange width

be= 670 · t/√(Fy )

l For I-section, T-section, Channel section, effective flange width and for Anglesection, effective length width

be= 200 · t/√(Fy )

But shall not exceed 60 · t

Laterally Unsupported Class 4 members subjected to bending

As per clause 13.6(b) the moment resistance for class-4 section shall be calculated as follows

i. When Mu > 0.67My

=

−

M ϕM1.15 1r y

M

M

0.28 y

u

Mr should not exceed ϕSeFyii. When Mu ≤ 0.67My

Mr=ϕMu

Where, as per clause 13.6(a),

Mu=(ω2 π)/L √(EIy GJ + (πE/L)2 Iy Cw )

For unbraced length subjected to end moments-

ω2=1.75 + 1.05k + 0.3k2 ≤ 2.5


When bending moment at any point within the unbraced length is larger than the largerend moment or when there is no effective lateral support for the compression flange at one ofthe ends of unsupported length-

ω2 = 1.0

k = Ratio of the smaller factored moment to the larger moment at opposite ends of theunbraced length, positive for double curvature and negative for single curvature.

Se = effective section modulus determined using effective flange width.

l For Rectangular HSS section, effective flange width

be= 670t/√(Fy )

l For I-section, T-section, Channel section, effective flange width and for Angle section,effective length width

be= 200t/√(Fy )

But shall not exceed 60t.

This clause is applicable only for I shaped and Channel shaped section as there is no guideline in the code for other sections.

3B.6.4 Members Subject to Combined Forces

Axial compression and bending

The member strength for sections subjected to axial compression and uniaxial or biaxialbending is obtained through the use of interaction equations. In these equations, theadditional bending caused by the action of the axial load is accounted for by usingamplification factors. Clause 13.8 of the code provides the equations for this purpose. If thesummation of the left hand side of these equations exceed 1.0 or the allowable value providedusing the RATIO parameter (See "Design Parameters" on page 141), the member is consideredto have failed under the loading condition.

Axial tension and bending

Members subjected to axial tension and bending are also designed using interactionequations. Clause 13.9 of the code is used to perform these checks. The actual RATIO isdetermined as the value of the left hand side of the critical equation.

3B.6.5 Shear

The shear resistance of the cross section is determined using the equations of Clause 13.4 ofthe code. Once this is obtained, the ratio of the shear force acting on the cross section to theshear resistance of the section is calculated. If any of the ratios (for both local Y & Z axes)exceed 1.0 or the allowable value provided using the RATIO parameter (see Table 3B.1), thesection is considered to have failed under shear. The code also requires that the slendernessratio of the web be within a certain limit (See Cl.13.4.1.3, page 1-29 of CAN/CSA-S16-01).

140 — STAAD.Pro


Checks for safety 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.

3B.7 Design ParametersThe design parameters outlined in Table 3B.1 may be used to control the design procedure.These parameters communicate design decisions from the engineer to the program and thusallow the engineer to control the design process to suit an application's specific needs.




CODE

BEAM 1.0 0.0 = designonly for endmoments andthose at locationsspecified 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

Table 3B.1-Canadian Steel Design CSA-S16-01 Parameters



CMY 1.0 1.0 = Do notcalculate Omega-1 for local Y axis.

2.0 = CalculateOmega-1 for localY axis.

Used in Cl.13.8.4of code

CMZ 1.0 1.0 = Do notcalculate Omega-1 for local Z axis.

2.0 = CalculateOmega-1 for localZ axis.

Used in Cl.13.8.4of code

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)

142— STAAD.Pro



DMIN 0.0 in. Minimumrequired depth(Applicable formemberselection)

FYLD 300.0 MPa Yield strength ofsteel.

FU 345.0 MPa Ultimatestrength of steel.

KT 1.0 K value forflexural torsionalbuckling.

KY 1.0 K value forgeneral columnflexural bucklingabout the local Y-axis. Used tocalculateslenderness ratio.

KZ 1.0 K value forgeneral columnflexural bucklingabout the local Z-axis. Used tocalculateslenderness ratio.

LT Member Length Length forflexural torsionalbuckling.

LY Member Length Length forgeneral columnflexural bucklingabout the local Y-axis. Used tocalculateslenderness ratio.



LZ Member Length Length forgeneral columnflexural bucklingabout the local Z-axis. Used tocalculateslenderness ratio.

MAIN 0.0 0.0 = Checkslenderness ratioagainst thelimits.

1.0= Suppress theslenderness ratiocheck.

2.0 = Checkslenderness ratioonly for columnbuckling, not forweb (See Section3B.6, Shear)

NSF 1.0 Net section factorfor tensionmembers.

RATIO 1.0 Permissible ratioof actual loadeffect to thedesign strength.

TRACK 0.0 0.0 = Report onlyminimum designresults.

1.0 = Reportdesign strengthsalso.

2.0 = Provide fulldetails of design.

144 — STAAD.Pro



UNB Member Length Unsupportedlength inbendingcompression ofthe bottomflange forcalculatingmomentresistance.

UNT Member Length Unsupportedlength inbendingcompression ofthe top flange forcalculatingmomentresistance.

3B.8 Code CheckingThe purpose of code checking is to check whether the provided section properties of themembers 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 the members. If theBEAM parameter for a member is set to 1, moments are calculated at every twelfth point alongthe beam. When no sections are specified and the BEAM parameter is set to zero (default),design will be based on member start and end forces only. The code checking output labelsthe members as PASSed or FAILed. In addition, the critical condition, governing load case,location (distance from the start joint) and magnitudes of the governing forces and momentsare also printed. The extent of detail of the output can be controlled by using the TRACKparameter.

Example of commands for CODE CHECKING:

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 CODE MEMB 3 4


3B.9 Member SelectionThe member selection process basically involves determination of the least weight memberthat PASSes the code checking procedure based on the forces and moments of the mostrecent analysis. The section selected will be of the same type as that specified initially. Forexample, a member specified initially as a channel will have a channel selected for it.Selection of members whose properties are originally provided from a user table will belimited to sections in the user table. Member selection cannot be performed on TUBES,PIPES or members listed as PRISMATIC.

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

3B.10 Tabulated Results of Steel DesignResults of code checking and member selection are presented in a tabular format. The termCRITICAL COND refers to the section of the CAN/CSA-S16-01 specification which governedthe design.

If the TRACK parameter is set to 1.0, factored member resistances will be printed. Following isa description of some of the items printed.

CRFactored compressive resistance

TRFactored tensile resistance

VRFactored shear resistance

MRZFactored moment resistance (about z-axis)

MRYFactored moment resistance (about y-axis)

Further details can be obtained by setting TRACK to 2.0.

CR1CAPACITY (Cr) PER 13.8.2(a)

CR2CAPACITY (Cr) PER 13.8.2(b)

146— STAAD.Pro


CRZSEE 13.8.2(b) for uniaxial bending (called CRX in that Clause)

CTORFLXCapacity in accordance with 13.8.2(c)

3B.11 Verification ProblemsIn the next few pages are included several verification examples for reference purposes. Sincethe S16-01 code is similar in many respects to the previous edition of the code (CAN/CSA S16.1-94), the solved examples of the 1994 edition of the CISC Handbook have been used as referencematerial for these examples.

3B.11.1 Verification Problem No. 1

Steel beam with uniform load, wide flange section. Static analysis, 3D beam element.

This example is included in the installation of STAAD.Pro as…/SProV8i/STAAD/Examp/Can/can_ver_prob1.std

Reference

CAN/CSA-S16.1-94, National Standard of Canada, Limit States Design of Steel Structures. TheCanadian Standards Association, 1994 with CISC (Canadian Institute 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 length 1.0 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

Critera Reference STAAD.Pro Difference

InteractionRatio

0.88 0.883 none

BeamResistance(kN·m)

284 283.20 none

BeamDeflection(mm)

21 20.81 none

Table 3B.2-CAN/CSA-S16 Verification Problem 1comparison

STAAD Output

**************************************************** * * * STAAD.Pro * * Version Bld * * Proprietary Program of * * Research Engineers, Intl. * * Date= *

* Time= * * * * USER ID: * ****************************************************

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 -7

148— STAAD.Pro


29. 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/ 2ORIGINAL/FINAL BAND-WIDTH= 1/ 1/ 5 DOFTOTAL PRIMARY LOAD CASES = 2, TOTAL DEGREES OF FREEDOM = 5SIZE OF STIFFNESS MATRIX = 1 DOUBLE KILO-WORDSREQRD/AVAIL. DISK SPACE = 12.0/ 19641.6 MB37. LOAD LIST 238. PRINT SECTION DISPLACEMENTSMEMBER SECTION DISPLACEMENTS----------------------------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 0.0000

0.0000 -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 3

0.00 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+02TENSILE CAPACITY = 1.805E+03 COMPRESSIVE CAPACITY = 2.732E+02FACTORED MOMENT RESISTANCE : MRY = 4.778E+01 MRZ = 2.832E+02FACTORED SHEAR RESISTANCE : VRY = 5.379E+02 VRZ = 4.604E+02MISCELLANEOUS 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


Steel beam/column, wide flange section. Static Analysis, 3D beam element.


Reference

CAN/CSA-S16.1-94, National Standard of Canada, Limit States Design of Steel Structures. TheCanadian Standards Association, 1994 with CISC (Canadian Institute of Steel Construction)handbook. CISC Handbook Example, Page 4_106.

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

150 — STAAD.Pro


200 kN*m and 300 kN*m

Steel section is W310X129

Comparison

Critera Reference STAAD.Pro Difference

InteractionRatio

0.96 0.98 2%

BeamResistance(kN·m)

583 584 none

ColumnResistance(kN)

3,800 3,820 none

Table 3B.3-CAN/CSA-S16 Verification Problem2comparison

STAAD Output

**************************************************** * * * STAAD.Pro * * Version Bld * * Proprietary Program of * * Research Engineers, Intl. * * Date= * * Time= * * * * 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


NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS = 2/ 1/ 2ORIGINAL/FINAL BAND-WIDTH= 1/ 1/ 5 DOFTOTAL PRIMARY LOAD CASES = 1, TOTAL DEGREES OF FREEDOM = 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

1 1 1 2000.00 135.14 0.00 0.00 0.00 300.002 -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



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

1 ST W310X129 (CANADIAN SECTIONS) PASS CSA-13.8.2C 0.980 1

2000.00 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)

152— STAAD.Pro


---------------------------------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 = 1.00SHEAR FORCE (KNS) : Y AXIS = 1.351E+02 Z AXIS = 0.000E+00SLENDERNESS 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


---------------- TOTAL = 4.694

MEMBER PROFILE LENGTH WEIGHT(METE) (KN )

1 ST W310X129 3.70 4.694************ END OF DATA FROM INTERNAL STORAGE ************42. FINISH


Steel beam/column, wide flange section. Static Analysis, 3D beam element.


Reference

CAN/CSA-S16.1-94, National Standard of Canada, Limit States Design of Steel Structures. TheCanadian Standards Association, 1994 with CISC (Canadian Institute of Steel Construction)handbook. CISC Handbook Example, Page 4-108.

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, 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 the weak axis.

Steel section is W310X143.

Comparison

Criteria Reference STAAD.Pro Difference

InteractionRatio

0.998 1.00 none

BeamResistance,Weak axis(kN·m)

300 299 none

BeamResistance,Strong axis(kN·m)

630 650 3.2%

ColumnResistance(kN)

4,200 4,222 none

Table 3B.4-CAN/CSA-S16 Verification Problem 3comparison

STAAD Output

**************************************************** * * * STAAD.Pro * * Version Bld * * Proprietary Program of * * Research Engineers, Intl. * * Date= * * Time= * * * * USER ID: * ****************************************************

1. STAAD SPACE VERIFICATION CISC 1994 HANDBOOK EXAMPLE PAGE 4-1082. *3. * ( COMPRESSION + BIAXIAL BENDING )4. *5. UNIT METER KN6. JOINT COORDINATES7. 1 0 0 0; 2 0 3.7 08. *9. MEMBER INCIDENCES

154 — STAAD.Pro


10. 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


NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS = 2/ 1/ 2ORIGINAL/FINAL BAND-WIDTH= 1/ 1/ 6 DOFTOTAL PRIMARY LOAD CASES = 1, TOTAL DEGREES OF FREEDOM = 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



FX MY MZ LOCATION ======================================================================= * 1 ST W310X143 (CANADIAN SECTIONS)

FAIL CSA-13.8.2A 1.000 12000.00 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 = 345.0


SECTION 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


----------------TOTAL = 5.171

MEMBER PROFILE LENGTH WEIGHT(METE) (KN )

1 ST W310X143 3.70 5.171************ END OF DATA FROM INTERNAL STORAGE ************42. FINISH


A slender, cantilever beam subjected to a uniform load. 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 3 KN/Meterin both major and minor axis. Axial compression of 8 KN is also applied to the member. Userdefined steel section Sect_Class-4 from is assigned to the member.

Given

Design forces

8.0 KN (Compression)

6.0 KNm (Bending-Y)

156— STAAD.Pro


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

Width of flange Bf = 150 mm

Thickness of flange Tf = 6 mm

Moment of inertia about Z axis, Iz = 1086.96X104 mm4

Moment of inertia about Y axis, Iy = 337.894X104 mm4

Moment of inertia about X axis, Ix = 3.7378X104 mm4

Warping constant, Cw = 1.752X1010 mm6

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/ *Cy)=(1100/sqrt(300))*(1-0.39*8000/(0.9*2766*300)) =63.24

Web is Class 1.

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 = *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 = *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 exceeds Class 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 mm4.

Effective section modulus about Y axis,

Syeff = 2657648.856/69.24 = 38383.144 mm3.

Major axis bending resistance if member is laterally supported,

158— STAAD.Pro


Mrz1 = *Szeff*FYLD= 0.9*135367.88*300 =36549327.6 N-mm.

Minor axis bending resistance,

Mry = *Syeff*FYLD = 0.9*38383.144*300 = 10363448.88 N-mm.

If the member is laterally unsupported major axis bending resistance is determined by clause13.6(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

Comparison

Criteria HandCal-

culation

STAAD.Pro Result Com-ments

Axialcom-pressiveresistance

521.73 KN 5.219X102 KN none

Major axisbendingresistance

36.549 KN-m

36.57 KN-m none

Minor axisbendingresistance

10.363 KN-m

10.38 KN-m none

Table 3B.5-CAN/CSA-S16 Verification Problem 4 comparison

STAAD Output

***************************************************** ** 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 EXAMPLE PAGE 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 INCIDENCES12. 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 -3

160 — STAAD.Pro


45. JOINT LOAD46. 2 FX -847. PERFORM ANALYSIS


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 FREEDOM = 6

48. LOAD LIST 149. PRINT MEMBER FORCES LIST 1VERIFICATION CISC 1994 HANDBOOK EXAMPLE PAGE 5-91 -- PAGE NO. 3

MEMBER END FORCES STRUCTURE TYPE = SPACE-----------------ALL UNITS ARE -- KN METE (LOCAL )

MEMBER LOAD JT AXIAL SHEAR-Y SHEAR-Z TORSION MOM-Y MOM-Z

1 1 1 8.00 6.00 6.00 0.00 -6.00 6.002 -8.00 0.00 0.00 0.00 0.00 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 MZ LOCATION

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


1 ST SECT_CLASS-4 (UPT)PASS CSA-13.8.3B 0.760 1

8.00 C -6.00 6.00 0.00

MEMBER PROPERTIES (UNIT = CM)-----------------------------

CROSS SECTION AREA = 2.77E+01 MEMBER LENGTH = 2.00E+02IZ = 1.09E+03 SZ = 1.45E+02 PZ = 1.63E+02IY = 3.38E+02 SY = 4.51E+01 PY = 6.92E+01IX = 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+02

TENSILE CAPACITY = 7.300E+02 COMPRESSIVE CAPACITY = 5.219E+02FACTORED MOMENT RESISTANCE : MRY = 1.038E+01 MRZ = 3.657E+01

MU = 2.486E+02FACTORED SHEAR RESISTANCE : VRY = 1.871E+02 VRZ = 3.208E+02

MISCELLANEOUS INFORMATION--------------------------

162— STAAD.Pro


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) = 2.000OMEGA-1 (Y-AXIS) = 1.00 OMEGA-1 (Z-AXIS) = 1.00 OMEGA-2 = 1.75SHEAR FORCE (KNS) : Y AXIS = 6.000E+00 Z AXIS = 6.000E+00SLENDERNESS RATIO OF WEB (H/W) = 1.97E+01

56. FINISH

*********** END OF THE STAAD.Pro RUN ***********

**** DATE= AUG 17,2010 TIME= 17: 6:28 ****

************************************************************* For questions on STAAD.Pro, please contact ** Bentley Systems Offices at the following locations ** ** Telephone Web / Email ** ** USA: +1 (714)974-2500 ** UK +44(1454)207-000 ** SINGAPORE +65 6225-6158 ** EUROPE +31 23 5560560 ** INDIA +91(033)4006-2021 ** JAPAN +81(03)5952-6500 http://www.ctc-g.co.jp ** CHINA +86 10 5929 7000 ** THAILAND +66(0)2645-1018/19 [email protected] ** ** Worldwide http://selectservices.bentley.com/en-US/ ** *************************************************************


164 — STAAD.Pro

3C. Canadian Codes - Design Per Canadian Cold FormedSteel Code S136-94

STAAD.Pro is capable of performing steel design based on the Canadian code S136-94Specification for the Design of Cold-Formed Steel Structural Members, including revisionsdated May, 1995. The program allows design of single (non-composite) members in tension,compression, bending, shear, as well as their combinations. For laterally supported members inbending, the Initiation of Yielding method has been used. Cold work of formingstrengthening effects have been included as an option.

Design of members per S136-94 requires the STAAD CAN/AUS/SA Design Codes SELECT CodePack.

3C.1 Cross-Sectional PropertiesThe user specifies the geometry of the cross-section by selecting one of the section shapedesignations from the Gross Section Property Tables published in the "Cold-Formed SteelDesign Manual", AISI, 1996 Edition.


l Channel with 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 graphical user interface(GUI) or by specifying the section designation symbol in the input file.


3C.2 Design ProcedureThe following two design modes are available:

3C.2.1 Code Checking

The program compares the resistance of members with the applied load effects, in accordancewith CSA 136. Code checking is carried out for locations specified via the SECTION commandor the BEAM parameter. The results are presented in a form of a PASS/FAIL identifier and aRATIO of load effect to resistance for each member checked. You may choose the degree ofdetail in the output data by setting the TRACK parameter.



3C.2.2 Member Selection

You may request that the program search the cold formed steel shapes database (AISIstandard sections) for alternative members that pass the code check and meet the leastweight criterion. In addition, a minimum and/or maximum acceptable depth of the membermay be specified. The program will then evaluate all database sections of the type initiallyspecified (i.e., channel, angle, etc.) and, if a suitable replacement is found, present designresults for that section. If no section satisfying the depth restrictions or lighter than theinitial one can be found, the program leaves the member unchanged, regardless of whether itpasses the code check or not.


3C.2.3 Code Sections Implemented

The program calculates effective section properties in accordance with Clauses 5.6.2.1 through3 and 5.6.2.6 through 8. Cross-sectional properties and overall slenderness of members arechecked for compliance with

l Clause 5.3, Maximum Effective Slenderness Ratio for members in Compression

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 the Standard asfollows:

l Resistance factors listed in Clauses 6.2 (a), (b), and (e) are used, as applicable.

l Members in tension - Resistance is calculated in accordance with Clauses 6.3.1 and6.3.2.

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 stress based onInitiation 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,

166— STAAD.Pro

3C. Canadian Codes - Design Per Canadian Cold Formed Steel Code S136-94

l 6.4.6 Combined Bending and Shear in Webs.

l Members in compression


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 Doubly Symmetric Sections.Input for the coefficients of uniform bending must be provided.

3C.3 Design ParametersThe following table contains the input parameters for specifying values of design variables andselection of design options.


ParameterName


CODE - Must be specified S136.



Table 3C.1-Canadian Cold Formed Steel Design Parameters


ParameterName


BEAM 1.0 When this parameter is set to 1.0(default), the adequacy of the memberis determined by checking a total of 13equally spaced locations along thelength of the member. If the BEAMvalue is 0.0, the 13 location check is notconducted, and instead, checking isdone only at the locations specified bythe SECTION command (See STAADmanual for details). If neither theBEAM parameter nor any SECTIONcommand is specified, STAAD willterminate the run and ask the user toprovide one of those 2 commands. Thisrule is not enforced for TRUSSmembers.

CMZ 1.0 Coefficient of equivalent uniformbending Ωz. See CSA 136, 6.7.2. Usedfor Combined axial load and bendingdesign. Values range from 0.4 to 1.0.

CMY 0.0 Coefficient of equivalent uniformbending Ωy. See CSA 136, 6.7.2. Usedfor Combined axial load and bendingdesign. Values range from 0.4 to 1.0.

CWY 0 Specifies whether the cold work offorming strengthening effect should beincluded in resistance computation.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. Thisvalue must be provided in the currentunits.

DMIN 0.0 Minimum depth required for thesection during member selection. Thisvalue must be provided in the currentunits.

168— STAAD.Pro


ParameterName


FLX 1 Specifies whether torsional-flexuralbuckling restraint is provided or is notnecessary for the member. See CSA 136,6.6.2

0. Section subject to torsionalflexural buckling and restraintnot provided

1. restraint provided orunnecessary

FU 450 MPa Ultimate tensile strength of steel incurrent units.

FYLD 350 MPa Yield strength of steel in current units.

KT 1.0 Effective length factor for torsionalbuckling. It is a fraction and is unit-less. 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 in axialcompression.

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 specified largevalue. It is used to compute the KL/Rratio for determining the capacity inaxial compression.

KZ 1.0 Effective length factor for overallcolumn buckling in the local Z-axis. Itis a fraction and is unit-less. Valuescan range from 0.01 (for a columncompletely prevented from buckling)to any user specified large value. It isused to compute the KL/R ratio fordetermining the capacity in axialcompression.


ParameterName


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 in axialcompression.

LY Memberlength

Effective length for overall columnbuckling in the local Y-axis. It is inputin the current units of length. Valuescan range from 0.01 (for a columncompletely prevented from buckling)to any user specified large value. It isused to compute the KL/R ratio fordetermining the capacity in axialcompression.

LZ Memberlength

Effective length for overall columnbuckling in the local Z-axis. It is inputin the current units of length. Valuescan range from 0.01 (for a columncompletely prevented from buckling)to any user specified large value. It isused to compute the KL/R ratio fordetermining the capacity in axialcompression.

NSF 1.0 Net section factor for tensionmembers, See CSA 136, 6.3.1.

STIFF Memberlength

Spacing in the longitudinal directionof shear stiffeners for stiffened flatwebs. It is input in the current units oflength. See section CSA 136, 6.4.5

170 — STAAD.Pro


ParameterName


TRACK 0 This parameter is used to control thelevel of detail in which the designoutput is reported in the output file.The allowable values are:

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 CSA 136,6.5. If true, the program uses the moreliberal set of interaction equations in6.4.6.

0. stiffeners do not comply with6.5

1. stiffeners comply with 6.5


172— STAAD.Pro

3D. Canadian Codes - Wood Design Per CSA StandardCAN/CSA-086-01

STAAD.Pro is capable of performing timber design based on the Canadian code CSA 086-01Wood Design Standard.

Design of members per CSA 086-01 requires the STAAD CAN/AUS/SA Design CodesSELECT Code Pack.

3D.1 General CommentsThe design philosophy of this specification is based on the concept of limit state design.Structures are designed and proportioned taking into consideration the limit states at whichthey would become unfit for their intended use. Two major categories of limit-state arerecognized - ultimate and serviceability. The primary considerations in ultimate limit statedesign are strength and stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for the entire structureunder various loading conditions and at the same time the chances of limits being surpassedare acceptably remote.

In the STAAD implementation, the code checking portion of the program checks whethercode requirements for each selected section are met and identifies the governing criteria.

The following sections describe the salient features of the STAAD implementation of CSA086-01. A detailed description of the design process along with its underlying concepts andassumptions is available in the specification document.

3D.2 Analysis MethodologyAnalysis is done for the primary and combination loading conditions provided by the user.The user is allowed complete flexibility in providing loading specifications and usingappropriate load factors to create necessary loading situations.

3D.3 Member Property SpecificationsA timber section library consisting of Sawn and Glulam timber is available for memberproperty specification.

For specification of member properties, for Sawn timber the timber section library available inSTAAD may be used. The next section describes the syntax of commands used to assignproperties from the built-in timber table.

For Glulam timber, member properties can be specified using the YD (depth) and ZD (width)specifications and selecting Combination and Species specifications from the built-in table.The assignment is done with the help of the PRISMATIC option (Refer to Section 5.20 of theTechnical Reference Manual)

3D.4 Built-in Timber Section LibraryThe following information is provided for use when the built-in timber tables are to bereferenced for member property specification. These properties are stored in a database file. Ifcalled for, the properties are also used for member design.


Following are the description of the different types of species combination available:

3D.4.1 Douglas Fir-Larch

The following example illustrates the specification of Douglas Fir-Larch species combination.

100 TO 150 TABLE ST DFL_SELSTR_2X2_BM

3D.4.2 Hem-Fir

Designation of Hem-Fir species combination in STAAD is as follows.

100 TO 150 TABLE ST HEM-FIR_SELSTR_2X10_BM

3D.4.3 Northern Species

Designation of Northern species combination in STAAD is as follows.

100 TO 150 TABLE ST NORTHERN_SELSTR_3X12_BM

3D.4.4 Spruce-Pine-Fir

Designation of Spruce-Pine-Fir species combination in STAAD is as follows.

100 TO 150 TABLE ST SPF_SELSTR_3X8_BM

3D.4.5 Glu Laminated timber

Designation of Glu-lam timber in STAAD involves defining the material, specifying thedimensions, and associating the material with the member through the CONSTANTScommand.

UNIT CM KN


ISOTROPIC GLT_D.FIR-L-24F-EX

E 51611.7

POISSON 0.15

DENSITY 2.5E-005

174 — STAAD.Pro

3D. Canadian Codes - Wood Design Per CSA Standard CAN/CSA-086-01

ALPHA 1.2E-011

END DEFINE MATERIAL

MEMBER PROPERTY TIMBER CANADIAN

1 PRIS YD 12 ZD 6

CONSTANTS

MATERIAL GLT_D.FIR-L-24F-EX MEMB 1

3D.4.6 Example

Sample input file to demonstrate usage of Canadian timber

STAAD PLANE EXAMPLE FOR DIMENSIONAL LUMBER

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


ISOTROPIC SPF_SELSTR_4X10_BM

E 1224

POISSON 0.15

DENSITY 25

ALPHA 5.5E-006

END DEFINE MATERIAL

MEMBER PROPERTY TIM 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_BM MEMB 1 TO 4 9 TO 11

MATERIAL SPF_SELSTR_4X10_BM MEMB 5 TO 8 12 13



FINISH

3D.5 Member ResistanceThe member resistances are calculated in STAAD according to the procedures outlined insection 5 (for sawn lumber) and 6 (for Glulam) of CSA086-01.

These depend on several adjustment factors as follows:

KDLoad duration factor (Clause 4.3.2.2-CSA086-01, Table 4.3.2.2)

KHSystem factor (Clause 5.4.4 and 6.4.3 and Table 5.4.4 -CSA086-01)

K_TTreatment factor (Clause 5.4.3 and 6.4.4 -CSA086-01)

KSBService condition factor applicable to Bending at extreme fibre (Table 5.4.2 and 6.4.2-CSA086-01)

KSVService condition factor applicable to longitudinal shear (Table 5.4.2 and 6.4.2CSA086-01)

KSCService condition factor applicable to Compression parallel to the grain (Table 5.4.2and 6.4.2 CSA086-01)

K_SCPService condition factor applicable to Compression perpendicular to the grain(Table 5.4.2 and 6.4.2 CSA086-01)

KSEService condition factor applicable to modulus of elasticity (Table 5.4.2 and 6.4.2 CSA086-01)

KSTService condition factor applicable to tension parallel to the grain (Table 5.4.2 and6.4.2 CSA086-01)

KZBSize factor applicable to bending (Clause 5.4.5 and Table 5.4.5 -CSA086-01)

KZVsize factor applicable to shear(Clause 5.4.5 and Table 5.4.5 -CSA086-01)

KZTsize factor applicable to tension parallel to grain (Clause 5.4.5 and Table 5.4.5 -CSA086-01)

KZCPsize factor applicable to compression perpendicular to grain (Clause 5.4.5 and Table5.4.5 -CSA086-01)

176— STAAD.Pro


K_ZCsize factor applicable to compression parallel to grain (Clause 5.4.5 and Table 5.4.5 -CSA086-01)

CHIXCurvature factor (Clause 6.5.6.5.2-CSA086-01)

CVshear load coefficient (Table 6.5.7.4A- CSA086-01)

KNNotch factor(Clause 5.5.5.4-CSA086-01)

All of these factors must be specified as input according to the classification of timber andstress grade.

Explained here is the procedure adopted in STAAD for calculating the member resistances.

3D.5.1 Axial Tension

i. For Sawn timber

The criterion governing the capacity of tension members is based on one limit state.The limit state involves fracture at the section with the minimum effective net area.The net section area may be specified by the user through the use of the parameter NSF(see Table 3B.1). STAAD calculates the tension capacity of a member based on this limitstate per Clause 5.5.9 of CSA086-01.

ii. For Glulam timber

The design of glulam tension members differs from sawn timber since CSA 086-01assigns different specified strength for gross and net section. The specified strength atnet section is slightly higher than the strength of the gross section. Therefore, Glulamtension members are designed based on two limit states. The first one is the limit stateof yielding in the gross section. The second limit state involves fracture at the sectionwith the minimum effective net area. The net-section area may be specified by the userthrough the 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 of CSA086-01.

3D.5.2 Axial Compression

The compressive resistance of columns is determined based on Clause.5.5.6 and Clause.6.5.8.4of CSA086-01. The equations presented in this section of the code assume that the compressiveresistance is a function of the compressive strength of the gross section (Gross section Areatimes the Yield Strength) as well as the slenderness factor (Kc). The effective length for thecalculation of compression resistance may be provided through the use of the parameters KX,KY, KZ, LX, LY and LZ (see Table 3B.1).

3D.5.3 Bending

The bending resistance of Sawn members are determined based on Clause 5.5.4 of CSA086-01and for glulam members are determined based on Clause 6.5.6.5 of CSA086-01. The allowable


stress in bending is multiplied by Lateral stability factor, KL to take in account whetherlateral support is provided at points of bearing to prevent lateral displacement and rotation

3D.5.4 Axial compression and bending

The member strength for sections subjected to axial compression and uni-axial or biaxialbending is obtained through the use of interaction equations. Clause 5.5.10 and 6.5.12 of thecode provides the equations 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 Table3B.1), the member is considered to have FAILed under the loading condition.

3D.5.5 Axial tension and bending

The member strength for sections subjected to axial tension and uniaxial or biaxial bending isobtained through the use of interaction equations. Clause 5.5.10 and 6.5.12 of the codeprovides the equations 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 Table3B.1), the member is considered to have FAILed under the loading condition.

3D.5.6 Shear

The shear resistance of the cross section is determined using the equations of Clause 5.5.5 and6.5.7.2 of the code. Once this is obtained, the ratio of the shear force acting on the crosssection 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 value provided using the RATIO parameter (see Table3B.1), the section is considered to have failed under shear.

3D.6 Design ParametersThe design parameters outlined in Table below may be used to control the design procedure.These parameters communicate design decisions from the engineer to the program and thusallows the engineer to control the design process to suit an application's specific needs.



178— STAAD.Pro


ParameterName


CODE - Must be specified as TIMBER 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 [Table 6.5.7.4A]

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, Table5.4.4]

KN 1.0 Notch Factor [Clause 5.4.7.2.2]

KSB 1.0 Service Condition Factor for Bendingat Extreme Fibre

Applicable for bending at extreme fibre[Table 5.4.2 and 6.4.2]

KSC 1.0 Service Condition Factor forCompression,

Applicable for compression parallel tograin [Table 5.4.2 and 6.4.2]

KSE 1.0 Service Condition Factor for Modulusof Elasticity,

Applicable for modulus of elasticity[Table 5.4.2 and 6.4.2]

KST 1.0 Service Condition Factor for Tension,

Applicable for tension parallel to grain[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 torsional buckling

Table 3D.1-Canadian Timber Design Parameters


ParameterName


KY 1.0 K value in local Y-axis, usually minoraxis

KZ 1.0 K value in local Z-axis, usually majoraxis

KZB 1.0 Size Factor for Bending,

Applicable for bending [Clause.5.4.5and Table 5.4.5]

KZCP 1.0 Size Factor for Compression,

Applicable for compressionperpendicular to grain [Clause .5.4.5and Table 5.4.5]

KZT 1.0 Size Factor for Tension,

Applicable for tension parallel to grain

[Clause 5.4.5 and Table 5.4.5]

KZV 1.0 Size Factor for Shear [Clause 5.4.5 andTable 5.4.5]

K_SCP 1.0 Service Condition Factor forCompression,

Applicable for compressionperpendicular to grain [Clause 5.4.2and Table 6.4.2]

K_T 1.0 Treatment Factor [Clause 5.4.3/6.4.4]

K_ZC 1.0 Size Factor for Compression,

Applicable for compression parallel tograin [Clause 5.4.5 and Table 5.4.5]

LX Memberlength

Length for flexural torsional buckling

LY Memberlength

Length in local Y axis for slendernessvalue KL/r

LZ Memberlength

Length in local Z axis for slendernessvalue KL/r

NSF 1.0 Net section factor for tension members

180 — STAAD.Pro


ParameterName


RATIO 1.0 Permissible Ratio of Actual toAllowable Value

3D.7 Code CheckingThe purpose of code checking is to check whether the provided section properties of themembers are adequate. The adequacy is checked as per the CSA086-01 requirements.

Code checking is done using forces and moments at specified sections of the members. Thecode checking output labels the members as PASSed or FAILed. In addition, the criticalcondition, governing load case, location (distance from the start joint) and magnitudes of thegoverning forces and moments are also printed.

Refer to Section 4.4 of the Technical Reference Manual for general information on CodeChecking. Refer to Section 5.51.2 of the Technical Reference Manual for details the specificationof 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

RATIO 0.99 ALL

CHECK CODE ALL

FINISH

3D.8 Member SelectionMember selection based CSA086-2001 is not available.


3D.9 Tabulated Results of Timber DesignResults of code checking and member selection are presented in a tabular format. The termCRITICAL COND refers to the section of the CSA086-01 specification, which governed thedesign.

PuActual Load in Compression

TuActual Load in Tension

MuyUltimate moment in y direction

MuzUltimate moment in z direction

VUltimate shear force

SLENDERNESS_YActual Slenderness ratio in y direction

SLENDERNESS_ZActual Slenderness ratio in z direction

PYFactored Compressive capacity in y direction

PZFactored Compressive capacity in z direction

TFactored tensile capacity

MYFactored moment of resistance in y direction

MZFactored moment of resistance in z direction

VFactored shear resistance

SLENDERNESSAllowable slenderness ratio

3D.10 Verification ProblemsThese verification examples are included for reference purposes.

3D.10.1 Verification Problem No. 1

Determine the Canadian Glulam section column in axial compression, with design perCanadian wood design code (CSA:086-01). Column is effectively pinned at both ends andbraced at mid-height in all direction.

This example is included in the installation of STAAD.Pro as…/SProV8i/STAAD/Examp/Can/canada_glulamcolumn.std

182— STAAD.Pro


Reference

Example 4, page 116, Canadian Wood Design Manual, 2001

Given

Length = 9000 mm

Comparison


DesignStrength (kN)

295 293.793 none

Table 3D.2-CAN/CSA-086-01 Verification Problem 1

Output for Member Design

STAAD.Pro CODE CHECKING - (S086)***********************

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/LOADING/

FX MY MZLOCATION

===================================================================-====

1 175.00X228.00 CANADIAN GLULAM GRADE:GLT_SPRUCE-PINE-12C-EPASS CL.5.5.10/6.5 0.728

1214.00 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|

| 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|

|--------------------------------------------------------------------------|

3D.10.2 Verification Problem: 2

Determine the bending capacity of a Canadian Glulam section single span floor beam, withdesign per Canadian wood design code (CSA:086-01). The compression edge assumed fullysupported.

This example is included in the installation of STAAD.Pro as…/SProV8i/STAAD/Examp/Can/canada_glulambeam.std

Reference


Given

Length = 7,500 mm, Beam Spacing = 5,000 mm, Standard load condition, Dry servicecondition, Untreated

184 — STAAD.Pro


Comparison


DesignStrength inBending(kN·m)

208 208.323 none

DesignStrength inShear (kN)

101 100.776 none






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

1 130.00X646.00 CANADIAN GLULAM GRADE:GLT_D.FIR-L-20F-EFAIL CL.5.5.5/6.5. 1.008 10.00 T 0.00 0.00 0.0000

|--------------------------------------------------------------------------|| LEZ = 7500.000 LEY = 7500.000 LUZ = 7500.000 LUY = 7500.000mm || || 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 = 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 ||--------------------------------------------------------------------------|



Determine the capacity of a Canadian Glulam section in axial tension, with design per theCanadian wood design code (CSA:086-01).

This example is included in the installation of STAAD.Pro as…/SProV8i/STAAD/Examp/Can/canada_glulamtension.std

Reference


Given

Dry service condition, Untreated

Comparison


DesignStrength inTension (kN)

257 256.636 none






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

1 80.00X266.00 CANADIAN GLULAM GRADE:GLT_SPRUCE-PINE-14T-EPASS 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) |

186— STAAD.Pro


| PY = 0.000 || PZ = 0.000 |

| T = 256.636 |

| MY = 0.000 || MZ = 0.000 || V = 0.000 ||--------------------------------------------------------------------------|


Determine the Canadian Sawn section column in axial compression, with design per theCanadian wood design code (CSA:086-01). Column is effectively pinned at both ends.

This example is included in the installation of STAAD.Pro as…/SProV8i/STAAD/Examp/Can/canada_sawn_lumber_column.std

Reference


Given

Unbraced Length = 5,000 mm

Comparison


DesignStrength (kN)

130 129.223 none






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

1 ST DFL_NO2_8X8_POSTPASS 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|| PZ = 129.223

|

| T = 0.000 || MY = 0.000 || MZ = 0.000 || V = 0.000 || SLENDERNESS = 50.000 ||--------------------------------------------------------------------------|


Determine the bending capacity of a Canadian sawn section single span floor beam, withdesign per the Canadian wood design code (CSA:086-01).

This example is included in the installation of STAAD.Pro as…/SProV8i/STAAD/Examp/Can/canada_sawn_lumber_beam1.std

Reference


Given

Length =6000mm, Beam Spacing = 3000mm, Standard load condition, Dry service condition,Untreated

Comparison


DesignStrength inBending(kN·m)

79.8 79.732 none

DesignStrength inShear (kN)

46.1 46.170 none


188— STAAD.Pro






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

1 ST DFL_NO1_10X16_BMFAIL CL.5.5.5/6.5.6 1.066 10.00 T 0.00 49.20 0.0000

|--------------------------------------------------------------------------|| 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 || 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 ||--------------------------------------------------------------------------|


Determine the capacity of a Canadian Sawn section in axial tension, with design per theCanadian wood design code (CSA:086-01).

This example is included in the installation of STAAD.Pro as…/SProV8i/STAAD/Examp/Can/canada_sawn_lumber_tension.std

Reference


Given

Dry service condition, Untreated


Comparison


DesignStrength inTension (kN)

185 184.338 none






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

1 ST DFL_NO1_6X8_BMPASS 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) || 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 ||--------------------------------------------------------------------------|

190 — STAAD.Pro


Section 4

Cypriot Codes


192— STAAD.Pro

4A. Cypriot Codes - Concrete Design in CyprusSTAAD.Pro is capable of performing concrete design based on the Cyrpiot code Seismic codefor reinforced concrete structures in Cyprus.

Design of members per this code requires the STAAD Eurozone Design Codes SELECT CodePack.


194 — STAAD.Pro

4B.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to the concrete code of Cyprus. These parameters not only act as a method to inputrequired data for code calculations but give the Engineer control over the actual designprocess. Default values of commonly used parameters for conventional design practice havebeen chosen as the basis. Table 4A.1 contains a complete list of available parameters with theirdefault values.


ParameterName

DefaultValue

Description

CODE - Must be specified as CYPRUS.


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 direction.






Table 4B.1-Cypriot Concrete Design Parameters


ParameterName

DefaultValue

Description


FC 4.0 ksi Concrete Yield Stress / cube strength, incurrent units

FYMAIN 60 ksi Yield Stress for main reinforcement, in currentunits (For slabs, it is for reinforcement in bothdirections)

FYSEC 60 ksi Yield Stress for secondary reinforcement a, incurrent units. Applicable to shear bars inbeams.

MAXMAIN

50 mm Maximum required reinforcement bar sizeAcceptable bars are per MINMAIN above.

MINMAIN 8 mm Minimum main reinforcement bar sizeAcceptable bar sizes: 6 8 10 12 16 20 25 32 40 50

MINSEC 8 mm Minimum secondary bar size a. Applicable toshear reinforcement in beams


NSECTION



0. No serviceability check performed.

1. Perform serviceability check for beamsas if they were continuous.

2. Perform serviceability check for beamsas if they were simply supported.

3. Perform serviceability check for beamsas if they were cantilever beams.


196— STAAD.Pro

ParameterName

DefaultValue

Description

SRA 0.0 Skew angle considered in Wood & Armerequations where A is the angle in degrees.

Two special values are also considered:

0.0 = Orthogonal reinforcementlayout without consideringtorsional moment Mxy -slabsonly

-500 = Orthogonal reinforcementlayout with Mxy used tocalculate Wood & Armermoments for design.

TRACK 0.0 Controls level of detail in output:

0. Critical Moment will not be printedwith beam design report. Columndesign gives no detailed results.

1. For beam gives min/max steel % andspacing. For columns gives a detailedtable of output with additionalmoments calculated.

2. Beam design only. Details ofreinforcement at sections defined bythe NSECTION parameter.



198— STAAD.Pro

Section 5

Danish Codes


200 — STAAD.Pro

5A. Danish Codes - Steel Design per DS412STAAD.Pro is capable of performing steel design based on the Danish code DS412 1998 Code ofPractice for the structural use of steel.

Design of members per DS412 1998 requires the STAAD N. Eurozone Design CodesSELECT Code Pack.


202— STAAD.Pro

5B.1 Design ParametersThe design parameters outlined in Table 5A.1 may be used to control the design procedure.These parameters communicate design decisions from the engineer to the program and thusallow you to control the design process to suit an application's specific needs.



ParameterName

DefaultValue

Description

CODE - Must be specified as DS412


See section 5.48.1 of the Technical ReferenceManual.

BEAM 1.0 1.0 = Calculate von Mises at twelfth points alongthe beam.

BY 1.0 Buckling length coefficient, Beta, about the localY axis.

BZ 1.0 Buckling length coefficient, Beta, about the localZ axis.

CB 1.0 Lateral buckling coefficient. Used to calculate theideal buckling moment.

CMY 1.0 Water depth, in meters, for hydrostatic pressurecalculation for pipe members.

CMZ 0.21 AlphaT in connection with lateral buckling.

CY Buckling curve coefficient, Alpha, about local Y-axis.

CZ Buckling curve coefficient, Alpha, about local Z-axis.

DMAX 1,000mm

Maximum allowable depth (Applicable formember selection)

Table 5B.1-Danish Steel Design DS412 Parameters


ParameterName

DefaultValue

Description

DMIN 0.0 mm Minimum required depth (Applicable for memberselection)

FYLD 235N/mm2

Yield strength of steel.

MF 1.15 Ratio of material factor to resistance factor.

RATIO 1.0 Permissible ratio of actual load effect to thedesign strength.

SSY Equivalent moment factor, BetaM, for local Y-axis.Valid values between 0 and 2.5.

SSZ Equivalent moment factor, BetaM, for local Z-axis.Valid values between 0 and 2.5.

TRACK 0.0 Used to specify a level of detail in output:

0. Report only minimum design results.

1. Report design strengths also.

2. Provide full details of design.

UNL MemberLength

Unsupported length in bending compression ofthe bottom flange for calculating momentresistance.

204 — STAAD.Pro

Section 6

Dutch Codes


206— STAAD.Pro

6A. Dutch Codes - Steel Design per NEN 6770STAAD.Pro is capable of performing steel design based on the Dutch code NEN 6770 TGB 1990- Steel structures - Basic requirements and basic rules for calculation of predominantlystaticaly loaded structures .

Design of members per NEN 6770 requires the STAAD N. Eurozone Design CodesSELECT Code Pack.

6A.1 Design ParametersAvailable design parameters to be used in conjunction with NEN 6770 are listed in table 6A.1along with their default values.

Note: 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.

ParameterName

DefaultValue

Description

CODE -

Must be specified as DUTCH



BEAM 3.0

Used to specify the number of sections to becheck along the length of the beam:

0. Check sections with end forces only.

1. Check at location of maximum Mzalong beam.

2. Check sections with end forces andforces at location of BEAM = 1.0 check.

3. Check at every 1/13th point of the beamand report the maximum.

Table 6A.1-Dutch Steel Design NEN 6770 Parameters


ParameterName

DefaultValue

Description

CMM 1.0

Loading type per Tables F.1.1 and F.1.2

1. Pin ended member with uniformloading

2. Fix ended member with uniformloading

3. Pin ended member with central pointload.

4. Fix ended member with central pointload.

5. Pin ended member with point loads atthird points.

6. Pin ended member with varying endmoments.

CMN 1.0

Used to describe the end restraints:

1.0 = No fixity

0.7 = One end fixed, the otherfree.

0.5 = Both ends fixed.

DFF

None(Mandatory

fordeflectioncheck,

TRACK 4.0)

"Deflection Length" / Maximum allowablelocal deflection

See Note 1d in Section 2B.6.

DJ1Start Jointof member

Joint No. denoting starting point forcalculation of "Deflection Length" . See Note 1below.

DJ2End Jointof member

Joint No. denoting end point for calculationof "Deflection Length". See Note 1 below.

DMAX 10,000 cm Maximum allowable depth

DMIN 0.0 cm Minimum allowable depth

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

208— STAAD.Pro

6A. Dutch Codes - Steel Design per NEN 6770

ParameterName

DefaultValue

Description

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

LYMemberLength

Length in local y - axis (current units) tocalculate (KY)(LY)/Ryy slenderness ratio.

LZMemberLength

Length in local z - axis (current units) tocalculate (KZ)(LZ)/Rzz slenderness ratio.

NSF 1.0 Net section factor for tension members.

PY

Setaccordingto steel

grade (SGR)

Design strength of steel

RATIO 1.0 Permissible ratio of the actual capacities.

SAME 0.0

Controls the sections to try during a SELECTprocess.

0. Try every section of the same type asoriginal

1. Try only those sections with a similarname as original (e.g., if the original isan HEA 100, then only HEA sectionswill be selected, even if there are HEM’sin the same table).

SBLT 0.0

Identify Section type for section classification

0. Rolled Section

1. Built up Section

SGR 0.0

Steel Grade

0. Grade Fe 360

1. Grade Fe 430

2. Grade Fe 510


ParameterName

DefaultValue

Description

TRACK 0.0

Used to control the level output detail:

0. Output summary of results.

1. Output summary of results withmember capacities.

2. Output detailed results.

3. Deflection Check (separate check tomain select / check code)

UNLMemberLength

Unrestrained member length in lateraltorsional buckling checks.

210 — STAAD.Pro

6A. Dutch Codes - Steel Design per NEN 6770

Section 7

European Codes


212— STAAD.Pro

7A. European Codes - Concrete Design Per Eurocode EC2STAAD.Pro is capable of performing concrete design based on the European code EC2 ENV1992-1-1:1991 E Eurocode 2: Design of concrete structures - Part 1-1: General rules and rules forbuildings.

Design of members per EC2 ENV 1992-1-1:1991 E requires the STAAD Eurozone Design CodesSELECT Code Pack.

7A.1 Design OperationsThe 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 on the designrequirements. The parameters referred to above provide the user with the ability to allocatespecific design properties to individual members considered in the design operation.

7A.2 Eurocode 2 (EC2)Eurocode 2, Design of concrete structures, Part 1, General rules and rules for buildings, providesdesign rules applicable to plain, reinforced or prestressed concrete used in buildings and civilengineering works. It is based on the limit state philosophy common to modern standards.

The objective of this method of design is to ensure that possibility of failure is reduced to anegligible level. This is achieved through application of factors to both the applied loads andthe material properties. The code also provides guidelines on the global method of analysis tobe used for calculating internal member forces and moments. STAAD provides a number ofmethods for analysis, allowing Geometric Nonlinearity as well as P-Delta effects to beconsidered.

7A.3 National Application DocumentsVarious authorities of the CEN member countries have prepared National ApplicationDocuments to be used with EC2. These documents provide alternative factors for loads andmay also provide supplements to the rules in EC2.

The current version of EC2 implemented in STAAD adheres to the factors and rules providedin EC2 and has not been modified by any National Application Documents.

7A.4 Material Properties and Load FactorsDesign resistances are obtained by dividing the characteristic yield strengths, as given in table2.3 of EC2, by the material partial safety factors γc for concrete and γs for reinforcements. Themagnitude in STAAD is 1.5 for concrete and 1.15 for reinforcements.

Material coefficients in STAAD take the following default values unless replaced by numericalvalues 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 actionunder consideration. In STAAD the user is allowed total control in providing applicablevalues for the factors and their use in various load combinations.

7A.5 ColumnsColumns are designed for axial compressive loads and possible moments at the ends of themember. If a particular load case causes tension in the column being designed that load caseis ignored, the design proceeds with a warning message given to that affect.

All active load cases will be considered in the design and reinforcements are assumedsymmetrically arranged in the cross section.

The maximum reinforcement calculated after all design load cases have been considered isthen reported as the critical required area of reinforcement.

Slender columns are also covered in the design process, the program will make due allowancefor the additional moment that has to be considered in the design.

Note: Sway type structures are not directly covered in the current implementation ofEC2. This effect, however, can be accounted for by the P-DELTA analysis option.

7A.6 BeamsBeams are designed for flexure, shear and torsion. For all these actions active load cases arescanned to create appropriate envelopes for the design process. Maximum torsional moment isalso identified and incorporated in the design.

7A.6.1 Design for flexure

Reinforcement for both positive and negative moments is calculated on the basis of thesection properties provided by the user. If the required reinforcement exceeds the maximumallowable then the section size is inadequate and a massage to that effect is given in theoutput. Parabolic-rectangular stress distribution for the concrete section is adopted and asmoment redistribution is not available in STAAD analysis, the limit for N.A to depth ratio isset according to clause 2.5.3.4.2 (5) of the code.

If required, compression reinforcement will be provided in order to satisfy the above limits. Itis important to know that beams are designed for the flexural moment MZ only. Themoment MY is not considered in the design at all.

214 — STAAD.Pro

7A. European Codes - Concrete Design Per Eurocode EC2


Shear reinforcement design is based on the standard method mentioned in clause 4.3.2.4.3where it is assumed the notional strut inclination is constant. Depending on the sheardistribution within the member it may be possible that nominal shear reinforcement will besufficient to cater for the design shear forces. If this is not the case an attempt is made toidentify regions where nominal reinforcement is insufficient and appropriate reinforcement isthen calculated to cover the excess design shear force.

The maximum shear force that can be carried without crushing the concrete is also checkedand if exceeded, a message to revise the section size is given in the output file.

7A.6.3 Design for Torsion

Torsional moments arising as a result of equilibrium requirements need to be designed for atthe ultimate limit state. Reinforcement for torsional moments consists of stirrups combinedwith longitudinal bars. The combined magnitude of shear stress arising from shear forces andtorsional moments are checked in order to establish whether the section size is adequate. Ifsection size is inadequate a massage is given in the output file, otherwise, full design is carriedout and both shear links and longitudinal bars required are calculated and, where necessary,links are combined with the shear force links and printed in a tabulated manner in the outputfile.

7A.7 SlabsSlabs can only be designed for if finite elements are used to represent them in the model ofthe structure. In the main the design follows the same procedure as for flexure except thatshear forces are assumed to be resisted without the provision of shear reinforcements. In caseswhere this may not be the case users must ensure that necessary checks are carried out. Theoutput for the slab design refers to longitudinal reinforcements, which coincides with thelocal x direction of the element, and, transverse reinforcement, which coincides with the localy direction of the element.

Also, reference is made to 'TOP' and BOTT' reinforcement which relates to the element's'TOP' and 'BOTTOM' as determined from the connectivity of the element. This may notcoincide with the slab's actual top and bottom and, if desired, you must ensure this throughthe numbering scheme of the elements. The design of the slab considers a fixed bar size of16mm in both directions with the longitudinal bar being the layer closest to the slab exteriorfaces. Refer to Figure 1.21 in Section 1.61. of the Technical Reference Manual for additionalinformation.

7A.8 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure. Dependingon the model being designed, the user may have to change some or all of the parameterdefault values. Some parameters are unit dependent and when altered, the new setting mustbe compatible with the active "unit" specification. Table 8A.1 lists all the relevant EC2parameters together with description and default values.



ParameterName


BRACE 0.0 0.0 = Column braced in bothdirections.

1.0 = Column unbraced aboutlocal Z direction only

2.0 = Column unbraced aboutlocal Y direction only

3.0 = Column unbraced in both Yand Z directions

CLEAR * 20mm Clearance of reinforcementmeasured from concrete surface toclosest bar perimeter.

DEPTH *YD Depth of concrete member. Thisvalue default is as provided as YDin MEMBER PROPERTIES.

EFACE *0.0 Face of support location at end ofbeam.

Note: Both SFACE & EFACEmust be positivenumbers.

ELY 1.0 Member length factor about localY direction for column design.

ELZ 1.0 Member length factor about localZ direction for column design.

FC * 30N/mm2 Concrete Yield Stress / cubestrength

FYMAIN *460 N/mm2 Yield Stress for mainreinforcement (For slabs, it is forreinforcement in both directions)

Table 7A.1-Concrete Design EC2 Parameters

216— STAAD.Pro


ParameterName


FYSEC *460N/mm2 Yield Stress for secondaryreinforcement. Applicable to shearbars in beams

MINMAIN 8mm Minimum main reinforcement barsize Acceptable bar sizes: 6 8 10 1216 20 25 32 40 50

MINSEC 8mm Minimum secondary bar size a.Applicable to shear reinforcementin beams

MAXMAIN 50mm Maximum required reinforcementbar size Acceptable bars are perMINMAIN above.

MMAG 1.0 Factor by which column designmoments are magnified

NSECTION 10 Number of equally-spaced sectionsto be considered in finding criticalmoment for beam design. Theupper limit is 20.

SERV 0.0 0.0 = No serviceability checkperformed.

1.0 = Perform serviceability checkfor beams as if they werecontinuous.

2.0 = Perform serviceability checkfor beams as if they were simplysupported.

3.0 = Perform serviceability checkfor beams as if they were cantileverbeams.

SFACE *0.0 Face of support location at start ofbeam. (Only applicable for shear -use MEMBER OFFSET for bending)


ParameterName


SRA 0.0 0.0 = Orthogonalreinforcement layout withoutconsidering torsional moment Mxy-slabs only

-500 = Orthogonal reinforcementlayout with Mxy used to calculateWood & Armer moments fordesign.

A = Skew angle consideredin Wood & Armer equations whereA is the angle in degrees.

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 withadditional moments calculated.

2.0 = Output of TRACK 1.0List of design sag/hog momentsand corresponding required steelarea at each section of member

WIDTH *ZD Width of concrete member. Thisvalue default is as provided as ZDin MEMBER PROPERTIES.

* Provided in current unit system

218— STAAD.Pro


7B. European Codes - Steel Design to Eurocode 3 [DD ENV1993-1-1:1992]

STAAD.Pro is capable of performing steel design based on the European code EC3 DD ENV1993-1-1:1992 Eurocode 3: Design of steel structures Part 1.1 General rules and rules for buildings.

Design of members per EC3 DD ENV 1993-1-1:1992 requires the STAAD Euro Design CodesSELECT Code Pack.

Note: The DD ENV 1993-1-1:1992 code has now been officially superseded by EN 1993-1-1:2005. Hence releases of STAAD.Pro subsequent to version SS3 (20.07.08.xx) will notsupport this design code. The SS3 build will perform member design to this codefor legacy files but has this code removed from the design codes list in the GUI.Users are advised to use the EN 1993-1-1:2005 version for Eurocode 3 design.

Hint: Design per EC3 DD ENV 1993-1-1:1992 is also available in the Steel Design mode inthe Graphical User Interface.

7B.1 General DescriptionThe main steps in performing a design operation are:


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 on the designrequirements. The ‘Parameters’ referred to above provide the user with the ability to allocatespecific design properties to individual members or member groups considered in the designoperation.

7B.1.1 Eurocode 3 DD ENV 1993-1-1:1992 (EC3 DD)

The DD ENV version of Eurocode 3, Design of steel structures, Part 1.1 General rules and rulesfor buildings (EC3 DD) provides design rules applicable to structural steel used in buildingsand civil engineering works. It is based on the ultimate limit states philosophy that iscommon to modern standards. The objective of this method of design is to ensure thatpossibility of failure is reduced to a negligible level. This is achieved through application ofsafety factors to both the applied loads and the material properties.

The code also provides guidelines on the global methods of analysis to be used for calculatinginternal member forces and moments. STAAD uses the elastic method of analysis which maybe used in all cases. Also there are three types of framing referred to in EC3. These are“Simple”, “Continuous”, and “Semi-continuous” which reflect the ability of the joints todeveloping moments under a specific loading condition. In STAAD only “Simple” and“Continuous” joint types can be assumed when carrying out global analysis.


7B.1.2 National Application Documents

Various authorities of the CEN member countries have prepared National ApplicationDocuments to be used with EC3. These documents provide alternative factors for loads andmay also provide supplements to the rules in EC3.

The current version of EC3 DD implemented in STAAD adheres to the factors and rulesprovided in DD ENV 1993-1-1:1992 and has not been modified by any National ApplicationDocument.

Note: National Annex documents are available for EC3 BS EN 1993-1-1:2005. See"European Codes - Steel Design to Eurocode 3 [EN 1993-1-1:2005]" on page 235

7B.1.3 Axes convention in STAAD and EC3

By default, STAAD defines the major axis of the cross-section as Z-Z and the minor axis as Y-Y. A special case where Z-Z is the minor axis and Y-Y is the major axis is available if the SET ZUP command is used and is discussed in Section 5.5 of the Technical Reference Manual. Thelongitudinal axis of the member is defined as X and joins the start joint of the member tothe end with the same positive direction.

EC3, however, defines the principal cross-section axes in reverse to that of STAAD, but thelongitudinal axis is defined in the same way. Both of these axes definitions follow theorthogonal right hand rule. See figure below.

Bear this difference in mind when examining the code-check output from STAAD.

Figure 7B.1 - Axis convention in STAAD and EC3

7B.2 Analysis MethodologyElastic analysis method is used to obtain the forces and moments for design. Analysis is donefor the primary and combination loading conditions provided by the user. The user is allowedcomplete flexibility in providing loading specifications and using appropriate load factors tocreate necessary loading situations.

7B.3 Material Properties and Load FactorsThe characteristic yield strength of steel used in EC3 DD design is based on table 3.1 of thecode. Design resistances are obtained by dividing the characteristic yield strength by the

220 — STAAD.Pro

7B. European Codes - Steel Design to Eurocode 3 [DD ENV 1993-1-1:1992]

material partial safety factor Γm. The magnitude of Γm in STAAD is 1.1 which is applicable toall section types. A separate safety factor parameter named GB1 is used to check the resistanceof a member to buckling and also has a default value of 1.1.

Material coefficients for steel in STAAD take the following default values unless replaced byuser’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 actionunder consideration. In STAAD the user is allowed total control in providing applicable valuesfor the factors and their use in various load combinations.

7B.4 Section ClassificationThe occurrence of local buckling of the compression elements of a cross-section prevents thedevelopment of full section capacity. It is therefore imperative to establish this possibility priorto determining the section capacities. Cross sections are classified in accordance with theirgeometrical properties and the stress pattern on the compression elements. For each load caseconsidered in the design process, STAAD determines the section class and calculates thecapacities accordingly.

The EC3 DD design module in STAAD can design members with all section profiles that are ofClass 1 2 or 3 as defined in section 5.3.2 of the code. However, the design of members that havea ‘Class 4’ section profile are limited to WIDE FLANGE, TEE, SINGLE CHANNEL, SINGLEANGLE, and RECTANGULAR HOLLOW SECTIONS. Also built-up user sections that are class4 sections are not dealt with in the current version of EC3 design in STAAD.Pro.

Laced and battened members are not considered in the current version of EC3 DD designmodule in STAAD.Pro.

7B.5 Member Design

7B.5.1 Design of Beams as per DD ENV 1993-1-1:1992

EC3 DD design in STAAD.Pro considers members that are primarily in bending and/or shearas beams and performs cross section and member capacity checks in accordance with the code.The main requirement for a beam is to have sufficient cross-section resistance to the appliedbending moment and shear force. The possibility of lateral-torsional buckling is also taken intoconsideration when the full length of the member has not been laterally restrained.

The bending capacity is primarily a function of the section type and the material yieldstrength and is determined according to Cl. 5.4.5 of the code. The shear capacity and thecorresponding shear checks are done as per section 5.4.6 of the code.


There are four classes of cross-sections defined in EC3. Class 1 and 2 sections can both attainfull capacity with the exception that the class 2 sections cannot sustain sufficient rotationrequired for plastic analysis of the model. Hence the full plastic section modulus is used inthe design calculations. Class 3 sections, due to local buckling, cannot develop plasticmoment capacity and the yield stress is limited to the extreme compression fibre of thesection. The elastic section modulus is used to determine the moment capacity for class 3sections. Class 4 sections do suffer from local buckling and explicit allowance must be madefor the reduction in section properties before the moment capacity can be determined.Further, because of interaction between shear force and bending moment, the momentresistance of the 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. In such casesthe web is assumed to resist the applied shear force as well as contributing towards themoment resistance of the cross-section.

As mentioned in the previous section, the design of class 4 sections is limited to WIDEFLANGE, TEE, SINGLE CHANNEL, SINGLE ANGLE, and RECTANGULAR HOLLOWSECTIONS. The effective section properties are worked out as described in Cl. 5.3.5 of thecode.

Beams are also checked for lateral-torsional buckling according to section 5.5.2 of the code.The buckling capacity is dependent on the section type as well as the unrestrained length,restraint conditions and type of applied loading. The lateral torsional buckling checksinvolves the calculation of the ‘Elastic critical moment’, Mcr, which is calculated in STAAD asper the method given in Annex F of the code.

In the presence of a shear force, beams are also checked for shear as per section 5.4.6 of thecode. In cases where the members are subject to combined bending and shear, the combinedbending and shear checks are done in STAAD as per clause 5.4.7 of the code.

7B.5.2 Design of Axially Loaded Members

The design of members subject to tension loads alone are performed as per Cl 5.4.3 of thecode. The tension capacity is calculated based on yield strength, material factor Γm and cross-sectional area of the member with possible reduction due to bolt holes. When bolt holes needto be considered in the capacity calculations the value used for Γm is 1.2 and the yieldstrength is replaced with the ultimate tensile strength of the material. The tension capacity isthen taken as the smaller of the full section capacity and the reduced section capacity asstated above.

The design of members subject to axial compression loads alone are performed as per Cl 5.4.4of the code. For members with class 1 2 or 3 section profiles, the full section area is consideredin calculating the section capacity. However in case of class 4 sections, the ‘effective cross-section’ is considered to calculate the compressive strength. Also any additional momentsinduced in the section due to the shift of the centroidal axis of the effective section will alsobe taken into account 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 for suchmembers. This is often the critical case as the buckling strength of the member is influenced

222— STAAD.Pro


by a number of factors including the section type and the unbraced length of the member.The buckling capacity is calculated as per Cl. 5.5 of the code.

DD ENV 1993-1-1:1992 does not specifically deal with single angle, double angles, doublechannels or Tee sections and does give a method to work out the slenderness of suchmembers. In these cases, the EC3 DD design module of STAAD.Pro uses the methods specifiedin BS 5950-1:2000 to calculate the slenderness of these members. Cl. 4.7.10 and table 25 of BS5950-1:2000 are used in the current version of the EC3 DD design module




Figure 7B.2 - Axis orientation for single angles

ST angle and USERtable angles

RA angle

7B.5.3 Design of members with combined axial load andbending

The bending resistance of members could be reduced by the presence of a co-existent axialload. This is then checked against the lateral-torsional buckling resistance of the section. TheEC3 DD design module in STAAD takes such a scenario into account and performs the


necessary checks as per Cl. 5.4.8 of the code. Class 1 and class 2 sections are checked as per cl.5.4.8.1 and Class 3 and Class 4 sections are checked as per clauses 5.4.8.2 and 5.4.8.3respectively. The effective section properties for class 4 sections are worked out as given in Cl.5.3.5 of the code.

Generally, EC3 requires checking cross-section resistance for local capacity and also checkingthe overall buckling capacity of the member. In the case of members subject to axial tensionand bending, there is provision to take the stabilizing effect of the tension load intoconsideration. This is achieved by modifying the extreme compression fibre stress andcalculating an effective applied moment for the section. The checks are done as per Cl. 5.5.3 ofthe code. In case of a combined axial compressive load and bending moment, the memberwill be checked as per the rules in section 5.5.4 of the code.

The presence of large shear force can also reduce the bending resistance of the section underconsideration. If the shear load is large enough to cause a reduction in bending resistance,then the reduction due to shear has to be taken into account before calculating the effect ofthe axial load on the bending resistance of the section. If the member is subject to acombined shear, axial load and bending moment then the section capacity checks will bedone as per Cl. 5.4.9 of the code.

As stated in the previous section, DD ENV 1993-1-1:1992 does not specifically deal with singleangle, double angles, double channels or Tee sections and does give a method to work outthe slenderness of such members. In these cases, the EC3 DD design module of STAAD.Prouses 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 to the note in section 5B.5.2 for St and RA angle specifications.

Please note that laced or battened compression members are not dealt within the currentversion of EC3 DD design module in STAAD.Pro.

7B.6 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure.

Depending on the model being designed, the user may have to change some or all of theparameter default values. Some parameters are unit dependent and when altered, the newsetting must be compatible with the active “unit” specification.

The following table lists all the relevant EC3 parameters together with description anddefault values.

224 — STAAD.Pro


ParameterName


CODE Undefined You must specify EC3 or EUROPE.



BEAM 3 Parameter to control the number ofsections to checked along the lengthof a beam:

0. Check sections with endforces only

1. Check at location ofmaximum Mz along beam

2. Check sections with endforces and forces at location ofBEAM 1.0 check.

3. Check at every 1/13th pointalong the beam and reportthe maximum

Refer to Note 2 below.

CAN 0 Member will be considered as acantilever type member fordeflection checks.

0 indicates that member will not betreated as a cantilever member

1 indicates that the member will betreated as a cantilever member

CMM 1.0 Indicates type of loading onmember. Valid values range from 1 to6.

Refer to Table 7B.3 for moreinformation on its use.

Table 7B.1-Steel Design Parameters EC3 DD


ParameterName


CMN 1.0 Indicates the level of End-Restraint.

1.0 = No fixity

0.5 = Full fixity

0.7 = One end free andother end fixed

DMAX 100.0 cm Maximum allowable depth for themember.

DMIN 0 Minimum required depth for themember.

DFF None (Mandatoryfor deflection

check)

Deflection limit

DJ1 Start Joint ofmember

Joint No. denoting starting point forcalculation of "Deflection Length".

DJ2 End Joint ofmember

Joint No. denoting end point forcalculation of "Deflection Length".

FU Ultimate tensile strength of steel

GB1 1.1 Partial safety factor used in bucklingchecks for compression members

GM0 1.1 Corresponds to the Γm0 factor in DDENV 1993-1-1:1992



KY 1.0 K factor in local y axis.

KZ 1.0 K factor in local z axis.

226— STAAD.Pro


ParameterName


LEG 0.0 Connection type

Refer to Note 1 below.

LVV Maximum of Lyyand Lzz (Lyy is aterm used byBS5950)

Buckling length for angle about itsprinciple 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)

PLG 0 (Polish NA only) Perform additionalchecks per Cl. 6.3.3

0. Ignore additional PN ENchecks

1. Include additional PN ENchecks

See "Clause 6.3.3(5) – Interactionfactors kyy, kyz, kzy, and kzz" onpage 326

PY Yield Strength The yield strength default value isset based on the default value of the"SGR" parameter.

NSF 1.0 Net tension factor for tensioncapacity calculation.

RATIO 1 Permissible ratio of loading tocapacity.

SBLT 0.0 Indicates if the section is rolled orbuilt-up.

0.0 = Rolled

1.0 = Built-up


ParameterName


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 adeflection check

See note 3 below.

UNF 1.0 Unsupported buckling length as afactor of the beam length

UNL Member Length Unrestraint length of member usedin calculating the lateral-torsionalresistance moment of the member.

ZIV 0.8 Specifies a reduction factor forvectoral effects to be used in axialtension checks [Cl 5.5.3(2)]

7B.6.1 Notes

1. LEG – (Ref: Table 25 BS5950)

The slenderness of single and double angle, channel and tee sections are specified inBS 5950 table 25 depending on the connection provided at the end of the member(Refer to section 5B.5(A).2). To define the appropriate connection, a LEG parametershould be assigned to the member.

The following table indicates the value of the LEG parameter required to match theBS5950 connection definition:

228— STAAD.Pro


Clause BoldConfiguration

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


4.7.10.5 TeeSections

(a) - 2 or more rows ofbolts

1.0


Table 7B.2-LEG Parameter values


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

La = KY * KY

Lb = KZ * LZ

The slenderness calculated for the v-v axis is then used to calculate the compressionstrength pc for the weaker principal axis (z-z for ST angles or y-y for RA specifiedangles). The maximum slenderness of the a-a and b-b axes is used to calculate thecompression strength pc for the stronger principal axis.

Alternatively for single angles where the connection is not known or Table 25 is notappropriate, by setting the LEG parameter to 10, slenderness is calculated for the twoprincipal axes y-y and z-z only. The LVV parameter is not used.

For double angles, the LVV parameter is available to comply with note 5 in table 25. Inaddition, if using double angles from user tables, (Refer to Section 1.7.3 of theTechnical Reference Manual) an eleventh value, rvv, should be supplied at the end ofthe ten existing values corresponding to the radius of gyration of the single anglemaking up the pair.

2. BEAM

Ensure that this parameter is set to either 1 or 2 while performing code checking formembers susceptible to Lateral - Torsional Buckling.

CMMVal-ue

Loading and Support Conditions

1

2

3

4

Table 7B.3-Values for the CMM Parameter

230 — STAAD.Pro


CMMVal-ue


5

6

3. Checking beam deflection

With the TRACK parameter set to 4, the members included in a CHECK CODE commandwill be checked for the local axis deflection rather than for the stress capacity using thecurrent LOAD LIST.

If both stress capacity and deflection checks are required, then 2 parameter blocks withcode checks are required, one with a TRACK 4 command and one with a TRACK 0, 1, or2, thus:

LOAD LIST 1 TO 10

PARAMETER 1

CODE EN 1993

TRACK 2 ALL

CHECK CODE MEMBER 1

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

LOAD LIST 100 TO 110

PARAMETER 2

TRACK 4 ALL

DFF 300 MEMB 1

DJ1 1 MEMB 1

DJ2 4 MEMB 1

CODE MEMB 1

Note:While both sets of code checks will be reported in the output file, only thelast code check results are reported in the GUI.

7B.7 Code CheckingThe purpose of code checking is to ascertain whether the provided section properties of themembers are adequate. The adequacy is checked as per DD ENV 1993-1-1:1992. Code checking isdone using the forces and moments at specific sections of the members.


When code checking is selected, the program calculates and prints whether the membershave passed or failed the checks; the critical condition ; the value of the ratio of the criticalcondition (overstressed for value more than 1.0 or any other specified RATIO value); thegoverning load case, and the location (distance from the start of the member of forces in themember where the critical condition occurs).

Code checking can be done with any type of steel section listed in Section 2B.4 or any of theuser defined sections as described in Section 1.7.3 of the Technical Reference Manual, withtwo exceptions; GENERAL and ISECTION. The EC3 DD design module does not consider thesesections or PRISMATIC sections in its design process.


7B.8 Member Selection STAAD is capable of performing design operations on specified members. Once an analysishas been performed, the program can select the most economical section, i.e., the lightestsection, which fulfills the code requirements for the specified member. The section selectedwill be of the same type section as originally designated for the member being designed.Member selection can also be constrained by the parameters DMAX and DMIN, which limitsthe maximum and minimum depth of the members.

Member selection can be performed with all the types of steel sections with the samelimitations as defined in section 5B.7(A) Code Checking.


Member selection cannot be performed on members whose section properties are input asprismatic or as the limitations specified in section 5.B.7(A).

7B.9 Tabulated Results of Steel Design For code checking or member selection, the program produces the results in a tabulatedfashion. The items in the output table are explained as follows:




CRITICAL CONDrefers to the clause in DD ENV 1993-1-1:1992 code which governs the design.

232— STAAD.Pro



LOADINGprovides the load case number, which governed the design.



Note: For a TRACK 2 output, the module will also report all the relevant clause checksthat have been performed and will also indicate the critical ratio and the load casethat caused the critical ratio as well as the corresponding forces that were used forthe respective checks. A TRACK 2 output will also include the various design dataused for the calculations such as the section modulii, section class, section capacityetc.


234 — STAAD.Pro

7C. European Codes - Steel Design to Eurocode 3 [EN 1993-1-1:2005]

STAAD.Pro is capable of performing steel design based on the European code EC3 BS EN 1993-1-1:2005 Eurocode 3: Design of steel structures Part 1.1 General rules and rules for buildings.

Note: The implementation of EN1993-1-1:2005 includes the amendments as per CENcorrigenda of February 2006 and April 2009.

Design of members per EC3 BS EN 1993-1-1:2005 requires the STAAD Euro Design CodesSELECT Code Pack.

7C.1 General DescriptionThe main steps in performing a design operation are:


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 on the designrequirements. The ‘Parameters’ referred to above provide the user with the ability to allocatespecific design properties to individual members or member groups considered in the designoperation.

7C.1.1 Eurocode 3 - EN 1993-1-1:2005 (EN 1993)

The EN 1993 version of Eurocode 3, Design of steel structures, Part 1.1 General rules and rulesfor buildings (EN 1993) provides design rules applicable to structural steel used in buildingsand civil engineering works. It is based on the ultimate limit states philosophy that iscommon to modern standards. The objective of this method of design is to ensure thatpossibility of failure is reduced to a negligible level. This is achieved through application ofsafety factors to both the applied loads and the material properties.

The code also provides guidelines on the global methods of analysis to be used for calculatinginternal member forces and moments. STAAD uses the elastic method of analysis which maybe used in all cases. Also there are three types of framing referred to in EC3. These are“Simple”, “Continuous”, and “Semi-continuous” which reflect the ability of the joints todeveloping moments under a specific loading condition. In STAAD only “Simple” and“Continuous” joint types can be assumed when carrying out global analysis.

7C.1.2 National Annex Documents

Various authorities of the CEN member countries have prepared National Annex Documentsto be used with EC3. These documents provide alternative factors for loads and may alsoprovide supplements to the rules in EC3.


The current version of EC3 (EN 1993)implemented in STAAD adheres to the factors and rulesprovided in EN 1993-1-1:2005. The current version of STAAD.Pro includes the followingNational 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 NA parameter that isset by the user when specifying the EN 1993 version of Eurocode 3. See "European Codes -National Annexes to Eurocode 3 [EN 1993-1-1:2005]" on page 281 for a description of the NAparameter.

7C.1.3 Axes convention in STAAD and EC3

By default, STAAD defines the major axis of the cross-section as Z-Z and the minor axis as Y-Y. A special case where Z-Z is the minor axis and Y-Y is the major axis is available if the SET ZUP command is used and is discussed in Section 5.5 of the Technical Reference Manual. Thelongitudinal axis of the member is defined as X and joins the start joint of the member tothe end with the same positive direction.

EC3, however, defines the principal cross-section axes in reverse to that of STAAD, but thelongitudinal axis is defined in the same way. Both of these axes definitions follow theorthogonal right hand rule. See figure below.

Bear this difference in mind when examining the code-check output from STAAD.

Figure 7C.1 - Axis convention in STAAD and EC3

See "Example of a TRACK 2 output" on page 278 for an example of how this appears when Y isup (default).

7C.2 Analysis Methodology

236— STAAD.Pro


Elastic analysis method is used to obtain the forces and moments for design. Analysis is donefor the primary and combination loading conditions provided by the user. The user is allowedcomplete flexibility in providing loading specifications and using appropriate load factors tocreate necessary loading situations.

7C.3 Material Properties and Load Factors The characteristic yield strength of steel used in EC3 (EN 1993) design is based on table 3.1 ofthe code. Design resistances are obtained by dividing the characteristic value of a particularresistance by the global partial safety factor for the resistance, γm. The magnitude of γm isbased on Cl. 6.1 of EN 1993-1-1:2005 and can change depending on the selected National Annex.

Material coefficients for steel in STAAD take the following default values unless replaced byuser’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 underconsideration. You are allowed total control in providing applicable values for the factors andtheir use in various load combinations.

7C.4 Section Classification The occurrence of local buckling of the compression elements of a cross-section prevents thedevelopment of full section capacity. It is therefore imperative to establish this possibility priorto determining the section capacities. Cross sections are classified in accordance with theirgeometrical properties and the stress pattern on the compression elements. For each load caseconsidered in the design process, the program determines the section class and calculates thecapacities accordingly. It is worth noting that the section class reported in the design outputcorresponds to the most critical loadcase among those being considered for design.

The EC3 (EN 1993) design module in STAAD can design members with all section profiles thatare of Class 1, 2, or 3 as defined in section 5.5 of the code. However, the design of members thathave 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 current version ofEC3 design in STAAD.Pro, unless they are defined as any of the section types given above.


The design of laced and battened members is not considered in the current version of EC3(EN 1993) design module in STAAD.Pro. The current version also does not support the designof tapered section profiles or I-Sections with top and/or bottom plates.

7C.5 Member Design EN 1993-1-1:2005, together with any specified National Annex, is used for code check orselection of all cross sections and shapes listed in Section 7C.4. However, where EN 1993 orthe National Annex has not specified a method or values for a specific clause or parameter,STAAD.Pro uses Non-Contradictory Complimentary Information (NCCI) documents asexplained in the following corresponding sections.

The design philosophy and procedural logistics are based on the principles of elastic analysisand ultimate limit state design. Two major failure modes are recognized:

l failure by overstressing

l failure by stability considerations

The following sections describe the salient features of the design approach. Members areproportioned to resist the design loads without exceeding the characteristic stresses orcapacities. Member selection is done on the basis of selecting the most economic section onthe basis of the least weight criteria. It is generally assumed that you (the engineer) will takecare of the detailing requirements, such as the provision of stiffeners, and check the localeffects like flange buckling, web crippling, etc.

Note: The design of class 4 (slender) sections is limited to WIDE FLANGE, TEE, SINGLECHANNEL, SINGLE ANGLE, and RECTANGULAR & CIRCULAR HOLLOWSECTIONS. The effective section properties are evaluated as described in Cl. 6.2.2.5of the code.

You are allowed complete control over the design process through the use of the parameterslisted in Table 7C.4. Default values of parameters will yield reasonable results in mostcircumstances. However, you should control the design and verify results through the use ofthe design parameters.

7C.5.1 Members Subject to Axial Loads

The cross section capacity of tension only members is checked for ultimate limit state asgiven in Cl. 6.2.3 of the code.

Compression members will be checked for axial capacity of the cross section in addition tolateral buckling/stability. The cross section capacity will be checked as given in section 6.2.4 ofthe code.

Lateral stability of a pure compression member will be checked as per the method given in Cl.6.3 of the code. The compression member stability will be verified as:

≤ 1.0N

N

Ed

b Rd,

Where Nb,Rd is the design buckling resistance given by:

238— STAAD.Pro


=Nb RdχA f

γ,y

M1 for Class 1, 2, or 3 cross-sections

=Nb RdχA f

γ,eff y

M1 for Class 4 cross-sections

Where:

χ is the reduction factor as given in section 6.3.12 of the code. The buckling curves used toevaluate the reduction factor are selected from Table 6.2 of the code based on the cross sectiontype and the steel grade.

Note: Only the five grades of steel given in table 6.2 will be used when selecting thebuckling curve. The steel grade used for this selection is based on the SGR designinput parameter (See "Design Parameters" on page 261). Even if you have specified acustom yield strength (using the PY parameter), the choice of a buckling curve willbe based on the value of SGR parameter.

Compression members that are susceptible to torsional or torsional flexural buckling arechecked for these modes of failure as well. The non-dimensional slenderness ¯λT for thesemembers is evaluated per Cl. 6.3.1.4 of the EN 1993 code. The maximum slenderness among theflexural buckling slenderness, torsional slenderness, and torsional-flexural slenderness is usedto evaluate the reduction factor, χ, for such members. The elastic torsional buckling load, Ncr,T, and the elastic torsional-flexural buckling load, Ncr,TF, are evaluated based on the methodgiven in the NCCI “SN001a-EN-EU: Critical axial load for torsional and flexural torsionalbuckling modes” (unless otherwise specified by a particular National Annex). The effectivelength for the members can be controlled using the KZ, KY, LZ and LY parameters. If theseparameters are specified, the effective length will be calculated as KZ*LZ for length about theZ-Z axis and KY*LY for length about the Y-Y axis. By default, the effective length will be takenas the member length.

EN 1993-1-1:2005 does not specifically deal with single angle, double angles, double channels, orTee sections and does not provide a method to evaluate the slenderness of such members. Inthese cases, the EC3 (EN 1993) design module of STAAD.Pro uses the methods specified in BS5950-1:2000 to calculate the slenderness of these members. Cl. 4.7.10 and Table 25 of BS 5950-1:2000 are used in the current version of the Eurocode 3 design module.





Figure 7C.2 - Axis orientation for single angles

ST angle andUSER table angles

RA angle

7C.5.2 Members Subject to Bending Moments

The cross section capacity of a member subject to bending is checked as per Cl .6.2.5 of thecode. The condition to be satisfied is:

≤ 1.0M

M

Ed

c Rd,

Where Mc,Rd is the is the design resistance given by:

= =M Mc Rd pl Rd

W f

γ, ,pl y

M0 for class 1 and 2 cross-sections

= =M Mc Rd el Rd

W f

γ, ,el y

M

,min

0 for class 3 cross-sections

=Mc RdW f

γ,eff y

M

,min

0 for class 4 cross-sections

Cross sectional bending capacity checks will be done for both major and minor axis bendingmoments.

Members subject to major axis bending will also be checked for Lateral Torsional Bucklingresistance as per Section 6.3.2 of the code. The design buckling resistance moment Mb,Rd willbe calculated as:

=M χ Wb Rd LT y

f

γ,y

M1

Where:

χLT is the reduction factor for lateral torsional buckling. This reduction factor is

240 — STAAD.Pro


evaluated per Cl. 6.3.2.2 or Cl 6.3.2.3 of the EN 1993 code depending on thesection type. For I sections, the program will by default use Cl. 6.3.2.3 to evaluteχLT and for all other sections the program will resort to Cl 6.3.2.2. However, if aparticular National Annex has been specified, the program will check if theNational Annex expands 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 inCl. 6.2.2.3 (or Table 6.5). For all other cases the program will use Cl. 6.3.2.2.

Note: You have the option to choose the clause to be used to calculate χLTthrough the MTH design parameter. Setting MTH to 0 (default value)will cause the program to choose Cl.6.3.2.3 for I Sections and Cl 6.2.3.2for all other section types. As mentioned above, if the National Annexexpands on Cl. 6.3.2.3 to include sections other than I Sections, theprogram will use Cl. 6.3.2.3 by default.

When using Cl. 6.3.2.3 to calculate χLT, the program will consider the correctionfactor kc (Table 6.6 of EN 1993-1-1:2006) based on the value of the KC parameterin the design input. By default the value of KC will be taken as 1.0. If you wantthe program to calculate kc, you must explicitly set the value of the KC parameterto zero.

Note: If the National Annex specifies a different method to calculate kc (e.g.the British, Singapore & Polish NAs), the program will use thatmethod by default even if the KC parameter has not been explicitly setto zero. If the NA method does not deal with a specific conditionwhile working out kc, the program will then fall back to table 6.6 ofthe code, thus ensuring that kc is considered for the particular NA.

The non-dimensional slenderness λLT (used to evaluate χLT) for both the above cases isevaluated as:

=λLTW f

M

y y

cr

Where:

Mcr is the elastic critical moment for lateral torsional buckling. EN 1993-1-1 doesnot however specify a method to evaluate Mcr. Hence, the program will make useof the method specified in Annex F of DD ENV 1993-1-1 to evaluate Mcr bydefault.

Note: The method specified in Annex F will be used only when the raw EN1993-1-1:2005 code is used without any National Annex. If a NationalAnnex has been specified, the calculation of Mcr (and λLT) will bedone based on the specific National Annex. (See "European Codes -National Annexes to Eurocode 3 [EN 1993-1-1:2005]" on page 281 for


specific details). If the National Annex does not specify a particularmethod or specify a reference document, the program will use theNCCI document SN-003a-EN-EU for doubly symmetric sections andSN030a-EN-EU for mono-symmetric sections that are symmetricabout their weak axis. For all other sections types the program willuse Annex F of DD ENV 1993-1-1 to calculate Mcr. In cases whereAnnex F does not provide an adequate method to evaluate Mcr, suchas for Channel sections, the program will resort to the method as perCl.4.3.6 of BS 5950-1:2000 to calculate the lateral torsional bucklingresistance moment (Mb,Rd) for the member.

7C.5.3 Members Subject to Shear

The cross section capacity of a member subject to shear is checked as per Cl. 6.2.6 of the code.The condition to be satisfied is:

≤ 1.0V

V

Ed

c Rd,

Where:

Vc,Rd is the is the shear design resistance given by:

= =V Vc Rd pl Rd

A f

γ

( ), ,

/ 3v y

M0

Av is the shear area and is worked out for the various section types as given inCl. 6.2.6(3) of the code.

Shear Buckling

For sections that are susceptible to shear buckling, the program will perform the shearbuckling checks as given in Section 5 of EN 1993-1-5. The shear buckling checks will be doneonly for I –Sections and Channel sections. Shear stresses induced from torsional loads aretaken into account while performing torsion checks.

Note:Web shear buckling is checked in STAAD.Pro V8i (SELECTseries 3) (release20.07.08) and later.

The susceptibility of a section to shear buckling will be based on the criteria given in Cl 5.1(2)of EN 1993-1-5 as is as given as follows:

a. For unstiffened webs, if hw/t > 72ε/η, the section must be checked for shear buckling.

The design resistance is calculated as:

= ≤V Vb Rd bw Rd

η f t

γ, ,

3

yw w

M1

242— STAAD.Pro


=Vbw Rdχ f h t

γ,

3

w yw w

M1

Where:

hw = distance between flanges of an I Section (i.e., depth - 2x flangethickness).

t = thickness of the web

ε = √(235/fy), where fy is the yield stress

η = 1.2 for steel grades up to and including S 460 and = 1.0 for other steelgrades

kτ as defined in sections below

χw is the web contribution factor obtained from Table 5.1 of the EC3 codeand is evaluated per the following table:

SlendernessParameter

Rigid EndPost

Non-rigid EndPost

λw < 0.83/η η η

0.83/η ≤ λw < 1.08 0.83/λw 0.83/λw

λw > 1.08 1.37/(0.7+ λw)

0.83/λw

Table 7C.1-Evaluate of χw

=⋅

λwh

t86.4 ϵ

w

b. For stiffened webs, if hw/t > 31·E√kτ/η, the section must be checked for shear buckling.

The design resistances considers tension field action of the web and flanges acting asstruts in a truss model. This is calculated as:

= + ≤V V Vb Rd bw Rd bf Rd

η f t

γ, , ,

3

yw w

M1

Where:

Vbf,Rd is the flange resistance per Cl.5.4 for a flange not completelyutilized by bending moment.

=

−

V 1bf Rd

h t f

cγ

M

M,

2f f yf

M

Ed

f Rd

2

1 ,

bf is the width of the flange which provides the least axial resistance, notto be taken greater than 15εtf on each side of the web.

tf is the thickness of the flange which provides the least axial resistance.


Mf,Rd = Mf,k/γM0, the moment of resistance of the cross sectionconsisting of the effective area of the flanges only. For a typical I Sectionor PFD, this is evaluated as b·tf·hw. When an axial load, NEd, is present,the value of Mf,Rd is reduced by multiplying by the following factor:

−

+

1NEd

A f A f fyf

γM

1 2

0

Af1 and Af2 are the areas of the top and bottom flanges, respectively.

=

+

c a 0.25

b t f

t h f

1.6 f f yf

w yw

2

2

a = transverse stiffener spacing. The equation of c is likewise used to solvefor a sufficient stiffener spacing in the case of demand from loadsexceeding the calculated capacity for a specified stiffener spacing.

The following equation must be satisfied for the web shear buckling check to pass:

= ≤η 1.0V

V3Ed

b Rd,

Where:

VEd is the design shear force.

Note: The shear forces due to any applied torsion will not be accounted for if the TORparameter has been specifically set to a value of 0 (i.e., ignore torsion option).

If the stiffener spacing has not been provided (using the STIFF parameter), then the programassumes that the member end forms a non-rigid post (case c) and proceeds to evaluate theminimum stiffener spacing required.

7C.5.4 Members Subject to Torsion

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

General

Eurocode 3 (EN 1993-1-1:2005) gives very limited guidance for the analysis and design oftorsion members. While both elastic and plastic analyses are permitted generally, the designanalysis methods for torsion discussed within EC3 are primarily based on elastic methods.Also, only the first yield design resistance is specifically discussed for torsion members.Furthermore, there is no guidance on section classification nor on how to allow for the effectsof local buckling on the design resistance for combined torsional effects. EC3 also does notspecifically deal 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.

244 — STAAD.Pro


The method used by STAAD.Pro is therefore based on the SCI publication “P057: Design ofmembers subject to combined bending and torsion”. Though this publication is based on theBritish standard BS 5950-1, the principles from this document are applied in the context ofEurocode 3.

Note: At the time this feature has been implemented in STAAD.Pro, SCI are in theprocess of updating document P057 to be in accordance with Eurocode 3. Hencethis method might be subject to modifications subject to the publication of a newerversion of P057. The NCCI document “SN007b-EN-EU: Torsion” will also bereferenced where appropriate.

Code Basis

Torsion design in EC3 is given in Cl. 6.2.7 of EN 1993-1-1:2005. Therefore, this clause is usedprimarily for this implementation.

EN 1993-1-1:2005 does not deal with members subject to the combined effects of torsion andlateral torsional buckling. However, EN 1993-1-6 considers such a condition in Appendix A.Therefore, STAAD.pro uses Appendix A of EN 1993-1-6 to check for members subject tocombined 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 output for all torsionchecks. Also any distortional deformations and any amplification in the torsional orshear stresses due to distortions will be neglected by the program.

l Clause 6.2.7(1)

States that for members subject to torsion, the design torsional moment TEd at eachcross section should satisfy:

TEd / RRd ≤ 1.0

Where:

TRd is the design torsional resistance of the cross section.

This is the primary condition that will need to be satisfied for members subject totorsion. The method for working out the torsional resistance TRd, for the various casesis 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 Vpl,Rdto Vpl,T,Rd and the design shear force should satisfy:

VEd / Vpl,T,Rd ≤ 1.0

The code also gives means to evaluate Vpl,T,Rd in equations 6.26 to 6.28. Theseequations, however, only deal with I/H sections, Channel sections, and structuralhollow sections (RHS, SHS, CHS). Therefore, the application of Cl. 6.2.7(9) is onlyperformed 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 may be used forelastic verification. STAAD.Pro evaluates the stresses due to the various actions on thecross section and applies this yield criterion.

The program allows for two types of checks for members subject to torsion for EC3 design:

I. Basic Stress Check: This method is intended to be a simplified stress check fortorsional effects. This method will produce the output corresponding to Cl. 6.2.7(5) ofEN 1993-1-1.

II. Detailed Checks: This method will perform a full torsional analysis of the member. Allfour 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 or group ofmembers. This will be facilitated by setting the value of the TORSION. The TORSION parameterset to zero by default, which results in torsion checks only being performed if the member issubject to torsional moments (i.e., for this default setting, the program will ignore torsionchecks if there is no torsional moment in the member). Setting the value of the TORSIONparameter to three (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 particular member.The details of setting the values to one (1) or two (2) and the corresponding checks performedare as described below. See "Design Parameters" on page 261 for additional details.

Note: If the TORSION parameter is set to 1 or 2, the program will perform the appropriatechecks even if the member is not subject to torsional moments. In such cases, theprogram will perform the checks with a value of zero for the torsional moment.

Basic stress check

This 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 be ignored for thisoption. The program will consider the forces (including torsion) at various sections along the

246— STAAD.Pro


length of the member and for each section, will calculate the resultant stress (Von Mieses) atvarious points on the cross section. The location and number of points checked for a crosssection will depend on the cross section type and will be as described below.

The stress check will be performed using equation 6.1 of EN 1993-1-1:2005 as given below:

+

−

+

≤3 1σ

f γ

σ

f γ

σ

f γ

σ

f γ

τ

f γ/

2

/

2

/ / /

2

x Ed

y M

z Ed

y M

x Ed

y M

z Ed

y M

Ed

y M

,

0

,

0

,

0

,

0 0

Where:

σx,Ed is the longitudinal stress

σz,Ed is the transverse stress and

τEd is the resultant shear stress.

Note: Since transverse stresses are very small under normal loading conditions (excludinghydrostatic forces), the term will be negligible and hence is taken as zero.

σx,Ed = σx + σbz + σby = Fx/Ax + Mz/Zz + My/ZyτEd = T/J · t + Vy·Q/(Iz·t) + Vz·Q/(Iy*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 a cross section asshown in figures below:


Shape Section Sketch

Doublysymmetricwide flangeprofile

Pipeprofiles

α =tan-1(Mz/My)

Tubeprofiles

248— STAAD.Pro


Shape Section Sketch

Channelprofiles

The resultant ratio will be reported under Cl. 6.2.7(5) in the detailed design output.

Detailed stress check

This method is used when the TORSION parameter is specified as two (2).

This method performs a detailed torsional analysis of a member depending on the torsionloading conditions and the support conditions at the member ends. This method is based onthe SCI publication P057 and includes any warping stresses (direct warping stresses andwarping shear stresses) depending on the end conditions of the member. This implementationconsiders seven different cases of loading and end conditions as given in publication P057 –Section 6. The loading/end conditions for a member are specified by the use of the CMT designparameter (See "Design Parameters" on page 261 for parameter values and descriptions).

All the equations used to evaluate the torsional moments and associated stresses are as givenin Appendix B of P057. The resultant stresses are evaluated at various sections along the lengthof the member and the following checks will be performed:

Clause 6.2.7(1) – Torsional resistance of the section.

In general, the torsion at any section TEd is resolved into two components, viz.

The pure torsional (St. Venant’s) moment (Tt,Ed) and

The warping torsional moment(Tw,Ed)

Therefore,


TEd = Tt,Ed + Tw,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 from theequations in Annex B of P057 and are based the specified CMT parameter.

Note: Although the equation given the NCCI document SN007b-EN-EU can be used toevaluate Twrd, the NCCI does not give the eqn. to evaluate φ’’’. Therefore, Annex Bof P057 is used.

The torsional resistance of the section is also considered as the sum of the pure torsionresistance and the warping torsion resistance. The pure torsion resistance (Tt,Rd) and thewarping torsional resistance (Tw,Rd) are evaluated as:

For closed sections:

Tt,Rd = 2 · Ac · t · τmaxWhere:

Ac is 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:

J is the torsion const

t is the max thickness.

Tw,Rd = (fy/ Γm0)· t · b2 / 6

Where:

b is the width of the section

t is the thickness of the flange for I- sections; minimum of flange or webthickness channel sections

The check according to Cl 6.2.7(1) will then be performed to ensure that the followingconditions are satisfied:

Tt,Ed / Tt,Rd ≤ 1

Tw,Ed / Tw,Rd ≤ 1

TEd / TRd ≤ 1

250 — STAAD.Pro


Clause 6.2.7(9) – Plastic shear resistance due to torsion

STAAD.Pro checks for shear resistance of a section based on Cl. 6.2.6 for EC3 and the plasticshear resistance (in the absence of torsion) is evaluated as:

=Vpl RdA f

γ

( ),

/ 3v y

M0

Where:

Av is as pre Cl.6.2.6 (3) for the various sections

When torsion is present, along with the shear force, the design shear resistance will bereduced to Vpl,T,Rd, where Vpl,T,Rd is evaluated as follows:

i. For I or H Sections:

= −V V1pl T Rd

τ

f γpl Rd( ), ,

1.25 / 3 /,

Ed

y M

,

0

ii. For Channel Sections:

=

− −

V V1pl T Rd

τ

f γ

τ

f γpl Rd( ) ( ), ,

1.25 / 3 / / 3 /,

Ed

y M

w Ed

y M

,

0

,

0

iii. For Structural Hollow Sections:

=

−

V V1pl T Rd

τ

f γpl Rd( ), ,

/ 3 /,

Ed

y M

,

0

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 insignificant andhence:

τt,Ed = TEd/(2·Ac·t)

[Ref NCCI Sn007b-EN-EU]

Where:

TEd is the applied torsion,

Ac is 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 and thereforewarping shear can be ignored (τw,Ed=0).

The stress due to pure torsion is evaluated as:

τt,Ed = G·t·φ’

[Ref SCI pub. P057]

Where:

G is the shear modulus

φ’ is a function depending on the end condition and loading(T). Thiswill be taken from section 6 and Annex B of P057.

Note: Although the maximum stress is at the thickest section of the profile, theprogram uses the web thickness for this clause (since the shear capacity isbased on the web area) unless the load is parallel to the flanges, in whichcase the flange thickness is used.

For channel sections that are free to warp at the supports and, thus, are not subject towarping stresses:

The warping shear stress is evaluated as:

τw,Ed = E·Sw·φ’’’ / t

[Ref SCI pub. P057]

Where:

E is the elastic modulus,

Sw is the warping statistical moment and

φ’ is a function depending on the end condition and loading(T). Thiswill 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 of yield

Eurocode 3 gives yield criterion as per eqn. 6.1 and STAAD.Pro uses the yield criterion givenin EC-3. When a member is subject to combined bending and torsion, some degree ofinteraction occurs between the two effects. The angle of twist caused by torsion is amplifiedby the bending moments and will induce additional warping moments and torsional shears.Account must also be taken of the additional minor axis moments produced by the majoraxis moments acting through the torsional deformations, including the amplificationsmentioned earlier.

For members subject to bending and torsion, the stresses are evaluated as follows:

252— STAAD.Pro


Direct bending stress (major axis): σbz = Mz / ZzDirect bending stress (minor axis): σby = My / ZyDirect stress due to warping: σw = E·Wns· φ’’

Direct stress due to twist (min. axis): σbyt = Myt / ZyDirect stress due to axial load (if any): σc = P/ A

Where:

Mz is the major axis moment & My is the minor axis moment.

φ’’ is the differential function based on twist (ref P057 Annex B. & Table 6)

Wns is the normalized warping function.

Myt = φ·Mz (see Appendix B of P057 to evaluate φ)

Shear stresses due to torsion and/or warping is evaluated as described above for Clause 6.2.7(9).

Check for yield (capacity checks) is then done according to Eqn 6.1 of EN 1993-1-1:2005, asdescribed for the Basic Stress Check (TORSION = 1):

+

−

+

≤3 1σ

f γ

σ

f γ

σ

f γ

σ

f γ

τ

f γ/

2

/

2

/ / /

2

x Ed

y M

z Ed

y M

x Ed

y M

z Ed

y M

Ed

y M

,

0

,

0

,

0

,

0 0

Clause EC-3:6 App A – Check for combined Torsion and Lateral Torsionalbuckling

The interaction check due to the combined effects of bending (including lateral torsionalbuckling) and torsion will be checked using Annex A of EN 1993-6: 2007. Note that thisinteraction equation does not include the effects of any axial load.

Warning: At present, SCI advises that no significant work has been published for this caseand work is still ongoing. So at present is advisable not to allow for torsion in amember with large axial load.

Members subject to combined bending and torsion will be checked to satisfy:

+ + ≤ 1M

χ M γ

C M

M γ

k k k T

T γ/ / /

y ED

LT y RK M

MZ z Ed

z RK M

w zw α w Ed

w Rk M

,

, 1

,

, 1

,

, 1

Where:

Cmz is the equivalent uniform moment factor for bending about the z-z axis,according to EN 1993-1-1 Table B.3.

= −k 0.7w

T

T γ

0.2

/

w Ed

w Rk M

,

, 1

= −k 1zw

M

M γ/

z Ed

z Rk M

,

, 1


=−

k α M M

1

1 /y Ed y cr, ,

My,Ed and Mz,Ed are the design values of the maximum moment about the y-yand z-z axis, respectively.

My,Rk and Mz,Rk are the characteristic values of the resistance moment of thecross-section about it y-y and z-z axis, respectively, from EN 1993-1-1, Table 6.7.

My,cr is the elastic critical lateral-torsional buckling moment about the y-y axis.

Tw,Ed is the design value of the warping torsional moment.

Tw,Rk is the characteristic value of the warping torsional resistance moment.

χLT is the reduction factor for lateral torsional buckling according to 6.3.2 of EN1993-1-1.

Note: For all of the above checks the effective length of the member to be used fortorsion can be set by using the EFT design parameter.

7C.5.5 Members Subject to Combined Forces

Members subject to Bending and Axial Force

When a member is subject to a combined axial load and a bending moment, the programevaluates a reduced moment capacity based on Cl. 6.2.9 of the code. For Class 1, 2, and 3sections, the program evaluates the reduced moment from the equations given in Cl. 6.2.9.1 ofthe code. For class 4 sections, the interaction equation given by equation 6.44 are checked.

In the case of members subject to axial load and biaxial bending, the program will considerthe interaction equation 6.41 of the code.

Note: By default, the program will use the values of the constants ‘α’ and ‘β’ as given inthe code for the different sections types. However, you can override these valuesusing the ALPHA and BETA design parameters (See "Design Parameters" on page261).

Note: The program uses the parameter ELB (See "Design Parameters" on page 261) tooverride the Cl.6.2.9 checks for combined axial load and bending case. Whenspecfied as 1, the program uses the more general equation 6.2 of EN 1993-1-1,instead.

Members subject to Bending, Shear, and Axial Force

When a member is subject to a combined axial load, shear force, and a bending moment, theprogram evaluates the reduced yield strength as given in Cl 6.2.10 (3) of the code. Thereduction in the yield strength is done only when the applied shear force exceeds 50% of the

254 — STAAD.Pro


design shear resistance Vpl,Rd. This reduced yield strength is then used to evaluate the reducedmoment capacity of the section.

Members subject to Bending and Axial Compression

The bending resistance of members could be reduced by the presence of a co-existent axialload. This is then checked against the lateral-torsional buckling resistance of the section. TheEN 1993 design module in STAAD takes such a scenario into account and performs thenecessary checks as per Cl. 6.3.3 of the code.

Generally, EC3 requires checking cross-section resistance for local capacity and also checkingthe overall buckling capacity of the member. In the case of members subject to axial tensionand bending, there is provision to take the stabilizing effect of the tension load intoconsideration. This is achieved by modifying the extreme compression fibre stress andcalculating an effective applied moment for the section. The checks are done as per Cl. 6.2.9 ofthe code. In case of a combined axial compressive load and bending moment, the member ischecked per the rules in 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 interaction factors kzz, kyy,kzy & kyz will be evaluated using Annex B of EN 1993-1-1 by default. Hence for the EN 1993-1-1code in STAAD.Pro (without National Annexes), uses Annex B. The choice between usingAnnex A and Annex B will be based on the choice specified by a particular National Annex, ifused. If the National 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, double angles, doublechannels or Tee sections and does give a method to evaluate the slenderness of suchmembers. In these cases, the Eurocode 3 (EN 1993-1-1) design module of STAAD.Prouses the methods specified in BS 5950-1:2000 to calculate the slenderness of thesemembers. Cl. 4.7.10 of BS 5950-1:2000 is used in the current version of the EC3design module. See "Single Angel Sections" for ST and RA angle specifications.

Note: Laced or battened compression members are not dealt within the current version ofEC3 (EN 1993) design module in STAAD.Pro.

7C.5.6 Design of Slender pipe sections to EN 1993-1-6

The design of Slender CHS sections is performed per EN 1993-1-6:2007 (hereafter, EC3-6). EC3-6 does not specify additional or modified safety factors. Therefore, the program uses thedefault safety factors from EN 1993-1-1.

Note: You can change these values through the GM0, GM1, & GM2 design parameters.

EC3-6 deals with four types of ultimate limits states: plastic limit state, cyclic capacity limitstate, buckling limit state, and fatigue. The following are considered by STAAD.Pro:


l LS1 – Plastic limit state: Deals with the condition when the capacity of the structure isexhausted by yielding of the material.

l LS3 – Buckling Limit state: Deals with the condition in which the structure (or shell)develops large displacements normal to the shell surface, caused by loss of stabilityunder compressive and/or shear membrane stresses.

The limit state verification is made based on the “Stress design” method described in EC3-6.The stress design approach takes into account three categories of stresses:

l Primary stresses: Stresses that are generated for the member to be in equilibrium withthe direct imposed loads.

l Secondary stresses: Those that are generated for internal compatibility or forcompatibility at supports due to imposed loads or displacements (e.g., temperature,settlement etc.)

l Local stresses: Local stresses generated due to cyclic loading (or fatigue).

Only the primary stresses are considered the program. The primary stresses considered arethose generated due to axial loads, bending, shear and /or a combination of these conditions.

Note: In the context of slender pipe section design for the Eurocode 3 module, thesecondary and local stresses can be neglected since the loads and correspondingstresses dealt with in the design engine are largely direct and shear stresses.

The local axis coordinate system for a CHS is defined as:

circumferentialaround the circumference of the circular crosssection (θ)

meridionalalong the length of the member (x)

normalperpendicular to the tangential plane formed bythe circumferential and meridional directions(n)

and the corresponding membrane stresses will follow the convention given below:

Figure 7C.3 - Nomenclature for membrane and transverse stresses in Slender CHS sections

Membrane stresses Transverse stresses

256— STAAD.Pro


Stress Design

Stress checks are made based on the “Stress design” method as per Section 8.5 of the code. Thissection deals with the buckling strength of the member (LS3). The principle is to evaluate themembrane stresses due to the applied loads and then compare that to the buckling strength,which is evaluated giving due consideration for local buckling effects.

The membrane stresses are evaluated as given in Annex A of the code. The pipe section isconsidered as an unstiffened cylindrical shell.

i. Meridional Stresses:

1. Axial load

Fx = 2·π·r·Pxσx = -Fx/(2·π·r·t)

2. Axial stress from bending

M = π·r2·Px,maxσx = ±M/(π2·r·t)

ii. Shear Stress:

1. Transverse force, V

V = π·r·Pθ,maxτmax = ±V/(π·r·t)

2. Shear from torsional moment, M

Mt = 2π·r2·Pθτ = Mt/(2π

2·r2·t)

Where:

r is the radius of the middle surface of the shell wall.

t is the wall thickness of the cylinder

Calculation of Axial Buckling Stress

The buckling strength of A slender pipe section is evaluated using the method given in section8.5.2 ofEC3-6. The design buckling stresses (buckling resistance) are calculated separately foraxial, circumferential, and shear. The circumferential stresses are ignored in STAAD.Pro.

The naming convention and the coordinate axis used will be as given in the followingdiagram:


Figure 7C.4 - Naming convention and coordinate system used for the buckling stress of a slender CSHsection

The axial buckling resistance is given by:

σx,Rd = σx,Rk/γM1

Note: ΓM1 will have the same default value of 1.0 as in EN 1993-1-1.

σx,Rk is the characteristic buckling strength given by:

σx,Rk = Χx· fykWhere:

χx is the meridional buckling reduction factor. χx is evaluated per Section 8.5.2(4) of EC3-6 and is determined as a function of the relative shell slendernessgiven by:

=λxf

σ

yk

x cr,

Where:

σx,cr is the elastic buckling critical stress.

Once the relative slenderness is evaluated, the reduction factor is calculated as follows:

χ = 1 when λ ≤ λ0

= −

−−

χ β1λ λ

λ λ

η

P

0

0 when λ0 < λ < λPχ = α/λ2 when λP ≤ λ

Where:

λp is the plastic limit for slenderness given by:

=−

λPα

β1

258— STAAD.Pro


The meridional buckling parameters the factors α and β are evaluated per section D.1.2.2 ofEC3-6.

Note: A ‘Normal’ fabrication quality will be assumed when evaluating the fabricationquality parameter as given in table D.2 of the code, unless the fabrication quality isset using the FAB design parameter. See "Design Parameters" on page 261

The elastic critical buckling stress, σx,cr and the factors α and β are evaluated per Annex D ofEC3-6. The details are as given below:

The CHS section is classified based on the following criteria:

CHS Length Classification Criteria

Short ω ≤ 1.7

Medium 1.7 < ω ≤ 0.5· r/t

Long ω > 0.5· r/t

Where:

=ω l

rt

The elastic critical buckling critical stress is evaluated as:

σx,Rcr = 0.605·E·Cx·(t/r)

Where:

Cx is a factor dependant upon the CHS length classification as described insection D.1.2.1 of EC-3-6.

Note: For a long cylinder, there are two separate methods that can be usedto evaluate the Cx factor: Eqns D.9/10 and Eqn D.12. Initially theprogram evaluates Cx based on the maximum from equations D.9 andD.10. However, for long cylinders that satisfy the conditions inequation D.11, the program will also work out Cx based on equationD.12 and then choose the minimum obtained from D.12 and D.9/10.

Calculation of Shear Buckling Stress

The shear buckling resistance is given by:

τxθ,Rd = τxθ,Rk/γM1

Note: γM1 will have the same default value of 1.0 as in EN 1993-1-1.

τxθ,Rk is the characteristic buckling shear strength given by:


τxθ,Rk = Χθ· fykWhere:

χθ is the shear buckling reduction factor. χθ will be worked out as given insection 8.5.2(4) of En 1993-1-6 and is determined as a function of the relativeshell slenderness given by:

=λθf

τ

yk

xθ cr,

Where:

τxθ,Rk is the elastic buckling critical stress.

The reduction factor, χθ, is then evaluated as described for the axial buckling stress, based onthe same λp, α, and β parameters given in Annex D of EC3-6.

The CHS section is classified based on the following criteria:

CHS Length Classification Criteria

Short ω ≤ 10

Medium 10 < ω ≤ 8.7· r/t

Long ω > 8.7· r/t

Where:

=ω l

rt

The elastic critical buckling critical stress is evaluated as:

=

τ EC0.75xθ Rcr τω r

,

1

Where:

Cτis a factor dependant upon whether the CHS length classification asdescribed in section D.1.4.1 of EC-3-6.

Note: A ‘Normal’ fabrication quality will be assumed when working out thefabrication quality parameter as given in table D.6 of the code, unlessthe fabrication quality is set using the FAB design parameter.

Buckling Strength Verification

The buckling strength verification will be performed so as to satisfy the following conditions:

For axial stresses:

σx,Ed ≤ σx,Rd

260 — STAAD.Pro


For shear stresses:

τxθ,Ed ≤ τxθ,RdFor a combined case of axial and shear stresses acting together, an interaction check will bedone according to equation 8.19 of the code as below:

+

≤ 1σ

σ

kτ

τ

k

x Ed

x Rd

xxθ Ed

xθ Rd

τ,

,

,

,

Where:

kx and kτ are the interaction factors as given in section D.1.6 of EN 1993-1-6:

kx = 1.25 + 0.75 · χxkτ = 1.75 + 0.25 · χτ

7C.6 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure.

Depending on the model being designed, you may have to change some or all of the parameterdefault values. Some parameters are unit dependent and when altered, the n setting must becompatible with the active “unit” specification.

Table 7C.4 lists all the relevant EC3 parameters together with description and default values.

ParameterName

DefaultValue

Description

CODE - Must be specified as EN 1993-1-1:2005 to invoke design per Eurocode3:2005 (EN 1993).



ALH 0.5 The ratio of the distance of the pointtorque (from the start of the member)to the length of the member. Thedefault value of 0.5 represents torqueacting at the mid-span of asymmetrically loaded member. Valuescan range from 0 to 1.

Table 7C.2-Steel Design Parameters EC3 EN


ParameterName

DefaultValue

Description

ALPHA 1.0 Used to input a user defined value forthe α factor in equation 6.41 forcombined bending and axial forcechecks.


1. Check at location of maximumMz along beam

2. Check sections with end forcesand forces at location ofBEAM 1.0 check.

3. Check at every 1/13th pointalong the beam and report themaximum

BETA 1.0 Used to input a user defined value forthe β factor in equation 6.41 forcombined bending and axial forcechecks.

C1 1.132 Corresponds to the C1 factor to beused to calculate Elastic criticalmoment Mcr as per Clause 6.3.2.2

C2 0.459 Corresponds to the C2 factor to beused to calculate Elastic criticalmoment Mcr as per Clause 6.3.2.2

C3 0 Corresponds to the C3 factor to beused to calculate Elastic criticalmoment Mcr as per Clause 6.3.2.2

262— STAAD.Pro


ParameterName

DefaultValue

Description

CAN 0 Member will be considered as acantilever type member for deflectionchecks.

0 indicates that memberwill not be treated as acantilever member

1 indicates that themember will be treatedas a cantilever member

CMM 1.0 Indicates type of loading and supportconditions on member. Used tocalculate the C1, C2, and C3 factors tobe used in the Mcr calculations.

Can take a value from 1 to 8.

Refer to Table 7C.5 for moreinformation 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 andother end fixed

CMT 1 Used to indicate the loading andsupport condition for torsion (ref. SCIpublication P-057).

Can take a value of 1-7. The valuescorrespond to the various casesdefined in section 6 and App. B ofSCI-P-057.

Refer to Table 7C.6 for moreinformation


ParameterName

DefaultValue

Description

DFF 0(Mandatory

fordeflectioncheck,

TRACK 4.0)

"Deflection Length" / Max.. allowablelocal deflection

See Note 1d below.

DJ1 Start Jointof member

Joint No. denoting starting point forcalculation of "Deflection Length" .See Note 1 below.


Joint No. denoting end point forcalculation of "Deflection Length". SeeNote 1 below.

DMAX 100.0 cm Maximum allowable depth for themember.

DMIN 0 Minimum required depth for themember.

EFT MemberLength

Effective length for torsion. A value of0 defaults to the member length.

ELB 0 Used to specify the method forcombined 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 EN1993-1-1:2005

264 — STAAD.Pro


ParameterName

DefaultValue

Description

ESTIFF 0 (For use with the Dutch NA only)Method for checking columnsforming part of (non)/buttressedframework:

0. Checks per Cl 12.3.1.2.3 of NEN6770: Section 1

1. Checks per Cl 12.3.1.2.3 of NEN6770: Section 2

See "Clause 12.3.1.2.3 (NEN 6770):Rotation/bending capacity" on page293 for additional description on thisparameter.

FAB 3 Used to specify the fabrication class tobe used to check for slender (Class 4)CHS/pipe sections (EN 1993-1-6:2007)

1. Class A – Excellent

2. Class B – High

3. Class C – Normal

FU 0 Ultimate tensile strength of steel.

GM0 1.0 Corresponds to the γm0 factor in EN1993-1-1:2005




ParameterName

DefaultValue

Description

GST 0 Used to specify the section type to beused for designing a “General Section”from the user table. The member willbe considered as the specified typewith the user defined properties. Theavailable options and correspondingvalues are as below:

0. I-Section

1. Single Channel

2. Rectangular Hollow Section

3. Circular Hollow Section

4. Angle Section

5. Tee Section

Note: This parameter will beignored if it has beenassigned to any sectionother than a GeneralSection.

KC 1.0 Corresponds to the correction factor asper Table 6.6 of EN 1993-1-1:2005.Program will calculate kcautomatically if this parameter is setto 0.

Note: For the British, Singapore,& Polish NAs, kc will becalculated as given in theNA by default.

KY 1.0 K factor in local y axis. Used tocalculate the effective length forslenderness and buckling calculations.

266— STAAD.Pro


ParameterName

DefaultValue

Description

KZ 1.0 K factor in local z axis. Used tocalculate the effective length forslenderness and buckling calculations.

LEG 0 Slenderness values for angles asdetermined from BS 5950-2000 Table25.

See "Design Parameters" on page 74

LVV Max. value ofLyy

Leg length for Lvv (length about v-v-axis of single angle section), as per Lyy.Used for slenderness calculations.

LY MemberLength

Compression length in local y axis,Slenderness ratio = (KY)*(LY)/(Ryy)

LZ MemberLength

Compression length in local z axis,Slenderness ratio = (KZ)*(LZ)/(Rzz)


ParameterName

DefaultValue

Description

MTH 0 Used to select the clause to be used tocalculate the LTB reduction factor,χLT. The available options andcorresponding values are as below:

0. Use default method based onsection type (default)

1. Use Cl.6.3.2.2

2. Use Cl.6.3.2.3

By default, the program will use Cl6.3.2.3 for rolled & built-up I-sectionsand Cl. 6.3.2.2 for all other sections. If,however, the specified National Annexexpands on Cl. 6.3.2.3 to include othersection types (e.g., the UK NA), theprogram will use Cl. 6.3.2.3 by defaultfor that particular section type.

See "European Codes - NationalAnnexes to Eurocode 3 [EN 1993-1-1:2005]" on page 281 for additionaldetails on NA documents.

MU 0 To be used with CMM values of 7 and 8.See Table 7C.4.

Note: Currently valid only withthe French & Belgian NAs.

NA 0 Choice of National Annex to be usedfor EC3 design. See "European Codes -National Annexes to Eurocode 3 [EN1993-1-1:2005]" on page 281 for valuesallowed for this parameter.

(See "National Annex Documents" onpage 235 for more information)

268— STAAD.Pro


ParameterName

DefaultValue

Description

NSF 1.0 Net tension factor for tension capacitycalculation.

PLG 0 To be used to determine whether toinclude the additional interactionchecks as per CL. NA.20(2) and NA.20(3) of the Polish National Annex.

Note: This parameter will beapplicable only to thePolish NA

PY YieldStrength

The yield strength default value is setbased on the default value of the SGRparameter.


SBLT 0.0 Indicates if the section is rolled orbuilt-up.

0.0 = Rolled

1.0 = Built-up


ParameterName

DefaultValue

Description

SGR 0 Steel grade as in table 3.1 of EN 1993-1-1:2005

0.0 - indicates S 235grade steel





Note: As EN 1993-1-1:2005 does

not provide a bucklingcurve in table 6.2 for gradeS 450 steel (in Table 3.1 ofEN 1993-1-1:2005), theprogram will use the samebuckling curves as for gradeS 460 when calculating thebuckling resistance as perclause 6.3.

STIFF MemberLength ordepth ofbeam,

whichever islesser

Distance between transverse stiffenerplates, used to prevent web shearbuckling. If not specified or if a valueof 0 is provided, the program willassume the web is unstiffened.

TOM 0 Total torsion for design used fortorsion checks. Can be used tooverride the total torsional moment tobe used for member design.

270 — STAAD.Pro


ParameterName

DefaultValue

Description

TORSION 0 Method to be used for a specificmember or group of members:

0. Perform basic torsion checks ifmember 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 thetorsion related checkedeven if torsional moment isabsent and will use a valueof zero for the torsionalmoment.

TRACK 0 Specify level of detail in output.

0. Summary of results only.

1. Summary with membercapacities.

2. Detailed results.

4. Deflection check results only.

UNF 1 Unsupported length as a fraction ofthe actual member length.

UNL MemberLength

Unrestrained length of member usedin calculating the lateral-torsionalresistance moment of the member.


ParameterName

DefaultValue

Description

ZG +SectionDepth/2

Distance of transverse load from shearcenter. Used to calculate Mcr.

Note: For Tee sections, ZG willhave a default value of(+Flange thickness/2)

Notes:

1. CAN, DJ1, and DJ2 – Deflection

a. When performing the deflection check, you can choose between two methods.The first method, defined by a value 0 for the CAN parameter, is based on thelocal displacement. Local displacement is described in Section 5.44 of theTechnical Reference Manual.

If the CAN parameter is set to 1, the check will be based on cantilever styledeflection. Let (DX1, DY1, DZ1) represent the nodal displacements (in globalaxes) at the node defined by DJ1 (or in the absence of DJ1, the start node of themember). Similarly, (DX2, DY2, DZ2) represent the deflection values at DJ2 orthe end node of the member.


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



b. If CAN = 0, deflection length is defined as the length that is used for calculationof local 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 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.

272— STAAD.Pro



PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

c. If DJ1 and DJ2 are not used, "Deflection Length" will default to the memberlength and local deflections will be measured from original member line.

d. It is important to note that unless a DFF value is specified, STAAD will notperform a deflection check. This is in accordance with the fact that there is nodefault value for DFF (see Table 2B.1).

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

2. CMM Parameter

The values of CMM for various loading and support conditions are as given below:

CMMVal-ue


1

2

3

4

Table 7C.3-Values for the CMM Parameter


CMMVal-ue


5

6

7

varying end moments and uniform loading

8

varying end moments and central pointload

3. Checking beam deflection

With the TRACK parameter set to 4, the members included in a BEAM CHECK commandwill be checked for the local axis deflection rather than for the stress capacity using thecurrent LOAD LIST.

If both stress capacity and deflection checks are required, then 2 parameter blocks withcode checks are required, one with a TRACK 4 command and one with a TRACK 0, 1or 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

274 — STAAD.Pro


DJ1 1 MEMB 1

DJ2 4 MEMB 1

CHECK CODE MEMB 1

Note:While both sets of code checks will be reported in the output file, only thelast code check results are reported in the STAAD.Pro graphical interface.

4. CMT Parameter

The values of CMM for various loading and support conditions are as given below:

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 incantilever. End Torsion fixed andWarping fixed

Table 7C.4-Loading and Support Conditions represented by CMTParameter Values


CMTValue

Description Diagram

7 Uniform Torque in cantilever.End Torsion fixed and Warpingfixed

Note: For CMT = 2 and CMT = 3, you have the option of specifying the distance atwhich the concentrated torque acts, measured from the start of themember. This can be done by using the ALH design parameter. The ALHparameter indicates the ratio of the distance of the point torque (from thestart of the member) to the length of the member. This parameter will havea default value of 0.5 (i.e., the torque acts at the center of the span) and willaccept values ranging from 0 to 1.

Note: The GB1 parameter that is being used for compression checks in builds precedingthis release (STAAD.Pro 2007 build 06) has been removed as this parameter is nolonger required in EN 1993-1-1:2005. Hence any legacy files that use GB1 parameterwill indicate an error message and you will be required to substitute GB1 with GM1,in accordance with EN 1993-1-1:2005.

7C.7 Code CheckingThe purpose of code checking is to ascertain whether the provided section properties of themembers are adequate. The adequacy is checked as per EN 1993-1-1:2005 and a correspondingNational Annex (if specified). 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 the membershave passed or failed the checks; the critical condition; the value of the ratio of the criticalcondition (overstressed for value more than 1.0 or any other specified RATIO value); thegoverning load case, and the location (distance from the start of the member of forces in themember where the critical condition occurs).

Code checking can be done with any type of steel section listed in Section 2B.4 or any of theuser defined sections as described in Section 1.7.3 of the Technical Reference Manual, with theexception of ISECTION. ISECTION has been currently excluded since the option of Taperedsection design is currently not supported in the EC3 module. The EC3 (EN 1993) designmodule does not consider these sections 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 & RECTANGULAR HOLLOWSECTIONS.

276— STAAD.Pro


Code checking for GENERAL sections can be also done using the EN1993 module. The programwill design GENERAL sections as I sections by default. However, you are given the option tochoose a ‘section type’ to be considered while designing the member. Refer to the descriptionof the GST design parameter in Section 7C.6 for details.

7C.8 Member SelectionSTAAD is capable of performing design operations on specified members. Once an analysis hasbeen performed, the program can select the most economical section, i.e., the lightest section,which fulfills the code requirements for the specified member. The section selected will be ofthe same type section as originally designated for the member being designed. Memberselection can also be constrained by the parameters DMAX and DMIN, which limits themaximum and minimum depth of the members.

Member selection can be performed with all the types of steel sections with the samelimitations as defined in Section 7C.7.


Member selection cannot be performed on members whose section properties are input asprismatic or as the limitations specified in Section 7C.7.

7C.9 Tabulated Results of Steel Design For code checking or member selection, the program produces the results in a tabulatedfashion. The items in the output table are explained as follows:




CRITICAL CONDrefers to the clause in EN 1993-1-1:2005 code which governs the design.


LOADINGprovides the load case number, which governed the design.




Note: For a TRACK 2 output, the module will also report all the relevant clause checksthat have been performed and will also indicate the critical ratio and the load casethat caused the critical ratio as well as the corresponding forces that were used forthe respective checks. A TRACK 2 output will also include the various design dataused for the calculations such as the section modulii, section class, section capacityetc.

If an NA parameter (other than 0) has been specified and if the particular National Annexrequires additional checks outside those specified in EN 1993-1-1:2005 (e.g., The DutchNational Annex), the respective NA clauses and any associated code clauses will be listedalong with the critical ratios and the forces that were used for these clause checks.

7C.9.1 Example of a TRACK 2 output

Documentation notes appear in red.

Note: The results and output follow the axis convention as described in Section 7C.1.3

Code title & versionSTAAD.PRO CODE CHECKING - BS EN 1993-1-1:2005

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

National Annex used, if anyNATIONAL ANNEX - NA to BS EN1993-1-1:2005

Design engine versionPROGRAM CODE REVISION V1.9 BS_EC3_2005/1



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

Member number, section profile & table1 ST HD320X127 (EUROPEAN SECTIONS)

Design status, critical code clause, & critical ratioPASS EC-6.3.3-662 0.045 1

Section forces & critical section location25.00 C 5.00-10.00 0.00

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

Grade of steel = USERModulus of elasticity = 205 kN/mm2Design Strength (py) = 275 N/mm2

SECTION PROPERTIES (units - cm)Member Length = 500.00Gross Area = 161.30 Net Area = 161.30

"z-axis" here refers to bending about Z-Z (when Y is Up), where as EC3 uses the Y-Y axis convention.

z-axis y-axis

278— STAAD.Pro


Moment of inertia : 30820.004 9239.001Plastic modulus : 2149.000 939.100Elastic modulus : 1926.250 615.933Shear Area : 81.998 51.728Radius of gyration : 13.823 7.568Effective Length : 500.000 500.000

DESIGN DATA (units - kN,m) EUROCODE NO.3 /2005

Section class as per Table 5.2Section Class : CLASS 1

Max. cross section capacity (A · fy/GM0Squash Load : 4435.75

Axial force/Squash load : 0.006

Partial safety factors usedGM0 : 1.00 GM1 : 1.00 GM2 :1.10

z-axis y-axisSlenderness ratio (KL/r) : 36.2 66.1Compression Capacity : 4078.2 3045.5Tension Capacity : 4435.8 4435.8Moment Capacity : 591.0 258.3Reduced Moment Capacity : 591.0 258.3Shear Capacity : 1301.9 821.3

BUCKLING CALCULATIONS (units - kN,m)Lateral Torsional Buckling Moment MB = 591.0

Factor C1 used in Mcrcalculations and End restraint factor (corresponds to the CMN design

parametersco-

e-fficientsC1 & K : C1 =2.578 K =1.0, Effective Length= 5.000

Elastic Critical Moment for LTB, Mcr = 1541.5Critical Load For Torsional Buckling, NcrT = 13898.0Critical Load For Torsional-Flexural Buckling, NcrTF = 13898.0



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

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

Max. ratio, loadcase, & section forces for each clause checkCLAUSE RATIO LOADFX VY VZ MZMYEC-6.3.1.1 0.008 1 25.0 0.0 0.0 -10.0 5.0EC-6.2.9.1 0.020 1 25.0 0.0 0.0 -10.0 5.0EC-6.3.3-661 0.035 1 25.0 0.0 0.0 -10.0 5.0EC-6.3.3-662 0.045 1 25.0 0.0 0.0 -10.0 5.0EC-6.3.2 LTB 0.017 1 25.0 0.0 0.0 -10.0 5.0

Torsion and deflections have not been considered in the design._________________________

************** END OF TABULATED RESULT OF DESIGN **************


280 — STAAD.Pro

7D. European Codes - National Annexes to Eurocode 3 [EN1993-1-1:2005]

A number of countries that have signed up to the replace their current steel design standardswith the Eurocode, EN 1993-1-1:2005, known commonly as Eurocode 3, have published theirNational Annex documents. These documents make small changes to the base document andSTAAD.Pro has been updated to incorporate some of these National Annex documents.

The parameter NA sets the default material gamma factors and any additional changes outlinedin the country specific National Annex such as specific equations or methods. These aredescribed for each National Annex document in the following sections.

The output file printout has been updated to indicate which National Annex (if any) has beenused in a code check / select process (For all TRACK settings).

Design of members per EC3 National Annexes requires the STAAD Euro Design CodesSELECT Code Pack.

7D.1 General FormatThe format of the EN 1993-1-1:2005 National Annex is as follows:

CODE EN 1993NA f1

Code parameters: See "Design Parameters" on page 261

Where: f1 represents the number designation for a specific country's National Annex:

NA Value Country

0 None — Uses the base EN 1993-1-1:2005 code, with nonational annex changes or additions. The default valuesspecified in En 1993-1-1:2005 will be used for the partialsafety factors and various parameter values whereapplicable (default).

1 United Kingdom (British NA) — Uses the BS EN 1993-1-1:2005 version of Eurocode 3 along with the UKNational Annex.

2 Netherlands (Dutch NA) — Uses the NEN EN 1993-1-1:2005 version of the code.

The Dutch National Annex [NEN-EN 1993-1-1/NB] hasbeen added in this module. Please note that the DutchNational requires additional checks as per NEN 6770and NEN 6771 which will also be performed duringdesign checks with this parameter value

Table 7D.1-Table 5B1.2(B) - Numerical Code for Eurocode National Annex


NA Value Country

3 Norway (Norwegian NA) — Uses the NS-EN 1993-1-1:2005 version of the code. The Norwegian NationalAnnexe [ NS-EN 1993-1-1:2005/Na 2008] has been addedto this implementation.

4 France (French NA) — Uses the Annexe Nationale a laNF EN 1993-1-1:2005 version of the code along with theFrench National Annex..

5 Finland (Finnish NA) - Uses the SFS EN 1993-1-1:2005version of Eurocode 3 along with the Finnish NationalAnnex.

6 Poland (Polish NA) - Uses the PN EN 1993-1-1:2005version of Eurocode 3 along with the Polish NationalAnnex.

7 Singapore (Singaporean NA) - Uses the SS EN 1993-1-1:2005 version of Eurocode 3 along with theSingaporean National Annex.

8 Belgium (Belgian NA) - Uses the NBN EN 1993-1-1:2005version of Eurocode 3 along with the Belgian NationalAnnex.

9 Malaysian (Malaysian NA) - Uses the MS NE 1993-1-1:2005 version of Eurocode 3 along with the MalaysianNational Annex.

7D.2 Specifying the design engine to use a nationalannexUse the following procedure to include additional check specified by a National Annex:

1. In the Modeling mode, select the Design | 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.

4. Select the NA parameter in the list box.

5. Select the option corresponding to the National Annex document you want to use .

6. Click Add.

This will insert the following commands into the STAAD input file:

282— STAAD.Pro

7D. European Codes - National Annexes to Eurocode 3 [EN 1993-1-1:2005]

CODE EN 1993-1-1:2005

NA n

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 the output file(*.ANL) with the following header, in addition to the base EC3 output.


7D.1 Dutch National Annex to EC3Adds values from the Dutch National Annex—titled NEN-EN 1993-1-1/NB—for use withEurocode 3, or EN 1993-1-1:2005. The NA document makes small changes to the basedocument.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that require additionalclauses from the Dutch National Annex (hereafter referred to as D-NA) are described in thefollowing sections.

Refer to the basic code (EC3) for a description of these clauses. The sections below refer to thecorresponding clauses in the D-NA.

Note: Clause 6.3.2.4 deals with a simplified assessment method for beams. STAAD.Pro onlyuses the more accurate method (6.3.2.2 and 6.3.2.3 in EC-3) and therefore thissection is ignored.

7D.1.1 Axis Convention

The local axis convention in the Dutch codes is: Y – major axis & Z – minor axis (as opposed tothe convention followed in STAAD.Pro).

Figure 7D.1 - Local axis convention used in the Dutch NA to EC-3

7D.1.2 Clause 6.1 – 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


The design function in STAAD.Pro sets these values as the default values for the D-NA (NA 3is specified)..

Note: You can change these values through the GM0, GM1, & GM2 design parameters. See"Design Parameters" on page 261

7D.1.3 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 NEN 6770.

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 in tables 10 &11 of NEN 6770.

Table 10 Provides interaction checks for bending about the major axis (All necessary termsand formulae are described below):

1. If Vz;s;d ≤ 0.5·Vz;pl;d and Ns;d ≤ 0.5 · a1 · Npl;d, check equation 11.3.1

2. If Vz;s;d ≤ 0.5·Vz;pl;d and Ns;d > 0.5 · a1 · Npl;d, check equation 11.3.2

3. If Vz;s;d > 0.5·Vz;pl;d and Ns;d ≤ 0.5 · a2 · Nv;u;d, check equation 11.3-3

4. If Vz;s;d > 0.5·Vz;pl;d and Ns;d > 0.5 · a2 · Nv;u;d, check equation 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 · fy;d / √3

fy;d = yield stress

285— STAAD.Pro

Figure 7D.2 - Definition of Aw

Aw = A - 2 (bf - tw - 2r) tf

Ns;d = Axial force in the section

Npl;d = Axial capacity of section = A · fy;dMy;s;d = Bending moment about major axis

My;pl;d = Plastic moment capacity of section = fy;d · 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

1. If Vy;s;d ≤ 0.25 · Vy;pl;d and Ns;d ≤ 1.0 · a1 · Npl;d check equation 11.3-5

2. If Vy;s;d ≤ 0.25 · Vy;pl;d and Ns;d > 1.0 · a1 · Npl;d check equation 11.3-6

3. IfVy;s;d > 0.25 · Vy;pl;d and Ns;d ≤ 1.0 · a1 · Nv;u;d check equation 11.3-7

4. If Vy;s;d > 0.25 · Vy;pl;d and Ns;d > 1.0 · a1 · Nv;u;d check equation 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

=V bt2y pl d f

f

; ;3

y d;


Mv;z;u;d = q · Mz;pld = q · fy;d · Wpl;z;d

Wpl;z;d = plastic section modulus about minor axis) & q as per eqn 11.3-14

Nv;u;d = Npl;d – 2·(1 - q)·bf · tf · fy;d

Clause 11.3.1.3 ( NEN 6770) : Class 1 and Class 2 Square andrectangular hollow sections

This clause requires class 1 and class 2 square and rectangular tube profiles to satisfy theinteraction equations in Table 13.

1. If Vz;s;d ≤ 0.25 · Vz;pl;d and Ns;d ≤ 0.5 · a3 · Npl;d check equation 11.3.22

2. If Vz;s;d ≤ 0.25 · Vz;pl;d and Ns;d > 0.5 · a3 · Npl;d check equation 11.3.23

3. If Vz;s;d > 0.25 · Vz;pl;d and Ns;d ≤ 0.5 · a4 · Nv;u;d check equation 11.3-24

4. If Vz;s;d > 0.25 · Vz;pl;d and Ns;d > 0.5 · a4 · Nv;u;d check equation 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 of section

h = height of section

A = area of section

= =+

V V Az pl d z cl dh

b h

f

; ; ; ;3

y d;

a3 = min (A - 2 · b · t)/A or 0.5

a4 = from equation 11.3.27

7D.1.4 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 to 11.3.2.3 of NEN 6770 andclause 11.3 of NEN 6771

Clause 11.3.1.1 (NEN 6770) and Clause 11.3.1.3 ( NEN 6770)

See "Clause 6.2.8 – Bending and shear" on page 285

Clause 11.3.1.2 (NEN 6770): Class 1 and class 2 circular hollow(CHS) profiles

Class 1 and class 2 sections with circular hollow profiles should satisfy the interactionequations given in table 12.

287— STAAD.Pro

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 "Clause 6.2.8 – Bending and shear" on page 285 of this document for equations to deriveVz;s;d

Vz;pl;d = Shear capacity of CHS sections

=V 2pl d

A

π

f

;3

y d;

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 above equationswith ‘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. The generalcondition to be satisfied in this case is given by equation 11.3-31 of NEN 6770

+

≤β β 1M

M

aM

M

a

0 1

y s d

N V y u d

z s d

N V z u d

; ;

; ; ; ;

1; ;

; ; ; ;

2

Clause 11.3.2.1 : Class 1 and class2 I-sections with biaxial 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 tables 14 and 15 ofNEN 6770 respectively.

Checks for table 14:

1. Check #1 – If Vz;s;d ≤ 0.5 Vz;pl;d and Ns;d ≤ 0.5 x a1 x Npl;d use equation 11.3.32

2. Check #2 – If Vz;s;d ≤ 0.5 Vz;pl;d and Ns;d > 0.5 x a1 x Npl;d use equation 11.3.33

3. Check #3 – If Vz;s;d > 0.5 Vz;pl;d and Ns;d ≤ 0.5 x a2 x Nv;u;d use equation 11.3-34

4. Check #4 – If Vz;s;d > 0.5 Vz;pl;d and Ns;d > 0.5 x a2 x Nv;u;d use equation 11.3-35

See "Clause 6.2.8 – Bending and shear" on page 285 for equations 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:

1. Check #1 – If Vy;s;d ≤ 0.25 Vy;pl;d and Ns;d ≤ 1.0 x a1 x Npl;d use equation 11.3.36

2. Check #2 – If Vy;s;d ≤ 0.25 Vy;pl;d and Ns;d > 1.0 x a1 x Npl;d use equation 11.3.37

3. Check #3 – If Vy;s;d > 0.25 Vy;pl;d and Ns;d ≤ 1.0 x a1 x Nv;u;d check equation 11.3-38

4. Check #4 – If Vy;s;d > 0.25 Vy;pl;d and Ns;d > 1.0 x a1 x Nv;u;d check equation 11.3-39

See "Clause 6.2.8 – Bending and shear" on page 285 for equations 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 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, seedescription of clause 11.3.2 above) are to be taken from table 17 of NEN 6770.

1. Check #1 – If Vz;s;d ≤ 0.25 Vz;pl;d use equation 11.3.44

2. Check #2 – If Vz;s;d > 0.25 Vz;pl;d use equation 11.3.45.

See "Clause 6.2.8 – Bending and shear" on page 285 for equations 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 NEN 6770.

Clause 11.3.2.3 : Class 1 and class2 Rectangular and squarehollow 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, seedescription of clause 11.3.2 above) are to be taken from table 19 of NEN 6770.

1. Check #1 – If Vz;s;d ≤ 0.25 Vz;pl;d and Ns;d ≤ 0.5 x a3 x Npl;d use equation 11.3-48

2. Check #2 – If Vz;s;d ≤ 0.25 Vz;pl;d and Ns;d > 0.5 x a3 x Npl;d use equation 11.3.49

3. Check #3 – If Vz;s;d > 0.25 Vz;pl;d and Ns;d ≤ 0.5 x a4 x Nv;u;d use equation 11.3-50

4. Check #4 – If Vz;s;d > 0.25 Vz;pl;d and Ns;d > 0.5 x a4 x Nv;u;d check equation 11.3-51

See "Clause 6.2.8 – Bending and shear" on page 285 for equations 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 beused for α1, α2, β1 and β2 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 above equationswith ‘y’.

Clause 11.3 ( NEN 6771)

In general, this section deals with Biaxial bending with axial force and shear for class 3 andclass 4 sections.

Check for class 3 sections: For class 3 sections use the method in section 11.3 NEN 6770. Forclass 3 sections the methods and equations discussed above can be used with the ‘plasticsection modulus’ being substituted with the ‘elastic modulus’.

Check for class 4 sections: Class 4 sections can be treated as class 3 sections if the effectivesection properties are used as given in clause 10.2.4.2.3 of NEN 6771. Working out the effectivesection properties for slender sections has already been done in STAAD.Pro.

For I- section profiles and tubular sections, the following cases are checked:

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

289— STAAD.Pro

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 limit state.

For an I section,

=V Az u d w et

f

; ;

2

3 ;3

y d;

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 the effectivesection. = ( fy·W,eff)

2. If M;y;s;d / MN;y;f;u;d > 1 and M;y;s;d / M;y;f;u;d ≤1 check equation 11.2-13 (given below):

≤+

−

−

−

1M

M M M 1 1

y s d

N y f u d N y u d N y f u d

Vz s d

Vz u d

; ;

; ; ; ; ; ; ; ; ; ; ;

2 ; ;

; ;

2

7D.1.5 Clause 6.3 – Buckling resistance of members

The D-NA introduces a new clause 6.3.0, which in turns requires the checks as per clauses12.1.2.2, 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 given as:

=λθ re

N

F,

c u d

E θ

; ;

;

Where:

Nc;u;d = A·fy;dA = area of section

fy;d = the yield stress

FE;θ is the Euler-torsion formula

This value of slenderness is to be used to calculate the modification factors used in section 6.3of EC-3.

Clause 12.1.3.2 (NEN 6771)

This clause works out the relative torsional-flexural buckling slenderness for compressionmembers. The relative torsional-flexural buckling slenderness is given as:

=λ tk re

N

F,

c u d

E tk

; ;

;


Where

Nc;u;d = A·fy;dA = 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. The effectivelength factors may be used to accommodate this requirement.

7D.1.6 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 of NEN 6770 andclause 12.1.1.3 of NEN 6771.

Clause 12.1.1.3 (NEN 6770)

This clause gives the equations to evaluate the effective lengths for various supportconditions. STAAD.Pro uses the effective length factor ‘K’ which allows the user to set/modifythe 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. We do not dealwith latticed section in the current version of STAAD.Pro. In any case the buckling lengthcan 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 and non-prismaticrods. Again, the ‘K’ factor in the current implementation of STAAD.Pro is adequate to caterfor adjusting the effective lengths as necessary.

7D.1.7 Clause 6.3.1.4 – Slenderness for torsional andtorsional-flexural buckling

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 for torsionalinstability.

If torsional checks need to be performed, they should be done according to 12.1.2 of NEN 6771.

291 — STAAD.Pro

Clause 12.1.2 (NEN 6771)

This clause gives the condition to check for torsion instability. The condition being:

≤ 1N

ω N

c s d

θ c u d

; ;

; ;

Where:

Nc;s;d = the applied axial load

NC;u;d = the axial capacity = A · fy.

=ωθσ

f

θ d

u d

;

;

Clause 12.1.3 (NEN 6770): Torsional flexural stability

Doubly symmetric sections need not be checked for torsional flexural instability. However, forI sections that have rigid supports that is not along the axis of the section and any othersections will need to be checked as per clause 12.1.3 of NEN 6771.

Clause 12.1.3 (NEN 6771)

This clause gives the condition to check for torsional flexural instability. The condition being:

≤ 1N

ω N

c s d

t k c u d

; ;

; ; ;

Where:

Nc;s;d and Nc;u;d as in clause 12.1.2 above.

7D.1.8 Clauses 6.3.2.2 and 6.3.2.3 – Lateral torsional bucklingcurves

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 in equation 6.56 ofEC-3 are to be obtained from sTable 6.3 of EC-3. These are the values used by STAAD.Pro.

Clause 6.3.2.3 – Lateral torsional buckling curves for rolledsections or equivalent welded sections

The D-NA states that:

1. The values for the:

l Imperfection factor αLT0 = 0.4 (used in equation 6.57 of EC-3)

l Β = 0.75 (used in equation 6.57 of EC-3)

These are the default values used by the program.


2. The buckling curves shall be selected as per Table 6.5.

3. The reduction factor, f, is given by

F = 1 – 0.5(1 - kc)[1 - 2x (λLT -0.8)2].

kc is a correction factor for moment distribution determined from Table 6.6. Thisvalue can be specified or calculated by the program using the KC parameter. See"Design Parameters" on page 261

The current implementation of STAAD.Pro conservatively uses a value of f = 1.0.

7D.1.9 Clause 6.33 – Uniform members in bending and axialcompression

The D-NA recommends the use of the method in Annex B of EC-3 to determine the values ofkyy, kyz, kzy and kzz to be used in 6.3.3 ( EC-3) checks. STAAD.Pro uses the method inAnnex B.

Clause 12.3.1.2.3 (NEN 6770): Rotation/bending capacity

The Dutch NA also requires additional checks as per clause 12.3.1.2.3 of NEN 6770.

The checks given in this clause deals with additional checks for columns that form part of abuttressed or non-butressed framework. The program uses the ESTIFF parameter with twodifferent values to identify the framework type:

ESTIFFvalue

Description

0

(default) Column part of a buttressedframework. Selecting this value willinternally perform the checks as per section1 of clause 12.3.1.2.3

1

Column is not part of a buttressedframework. Selecting this value willinternally perform the checks as per section2 of clause 12.3.1.2.3

Table 7D.1-Framework parameter ESTIFF values for theDutch NA

These checks are described below:

1. For columns in buttressed frameworks the buckling length is to be taken based oneither

l the system length or

l the distance between adjacent lateral supports

The following conditions should also be satisfied:

293— STAAD.Pro

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

+ ≤ 1N

N

λ

120

c s d

p d

y; ;

;

Where:

Nc;s;d is the axial load in the section

Npl;d = Axial capacity of section = A·fy;dλy = 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

+ ≤ 1N

N

λ

100

c s d

p d

y; ;

;

Where:

Nc;s;d = the axial load in the section


2. For columns that are not part of buttressed frameworks the following additional checksneed to be done:

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

+ ≤ 1N

N

λ

100

c s d

p d

y; ;

;

Where:

Nc;s;d = the axial load in the section and


If Nc;s;d/ Npl;d ≥ 0.15 and the steel grade is S355 then

+ ≤ 1N

N

λ

80

c s d

p d

y; ;

;


7D.1 Norwegian National Annex to EC3Adds values from the Norwegian National Annex—titled NA to BS EN 1993-1-1:2005—for usewith Eurocode 3, or EN 1993-1-1:2005. The NA document makes small changes to the basedocument.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that require additionalclauses from the Norwegian National Annex are:

7D.1.1 Clause 6.1(1) – General: Partial Safety Factors forbuildings

EN 1993-1-1:2005 specifies the use of the partial safety factors to be used in for design as givenin Cl. 6.1 of the code. These factors are γM0, γM1, and γM2. EN 1993 provides default values forthese factors. However, any National Annex is allowed to override these default values.


l Resistance of cross-sections - γM0 = 1.05

l Resistance of members to instability - γM1 = 1.05

l Resistance of cross sections to tension - γM2 = 1.25

The design function in STAAD.Pro sets these values as the default values for the Norwegian-NA (NA 3 is specified).


Note: If any of these parameters are specified as 0, STAAD.Pro will ignore the userspecified value (i.e., 0) and use the default values as given above.

Refer to the basic code (EC3) for a description of these clauses. The sections below refer to thecorresponding clauses in the Norwegian -NA.


7D.1 UK National Annex to EC3Adds values from the UK National Annex - titled NA to BS EN 1993-1-1:2005 - for use withEurocode 3, or EN 1993-1-1:2005. The NA document makes small changes to the basedocument.

Note: Refer to the basic code (EC3) for a description of these clauses. The sections belowrefer to the corresponding clauses in the UK-NA.

The following clauses are not implemented in STAAD.Pro:

Clause 6.3.2.4(1) B – Slenderness for flexural bucklingThe 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. However, STAAD.Pro does not use thisclause for design per EC-3. Therefore, this clause is ignored for the UK NationalAnnex.

Clause 6.3.2.4(2)B – Modification factor ‘kfl’The value of the modification factor kfl to be used in equation 6.60 of BS EN 1993-1-1. However, STAAD.Pro does not use this clause for design per EC-3. Therefore, thisclause is ignored for the UK National Annex.

The clauses/sections in EN 1993-1-1:2005 that have been dealt with in the UK National Annex(hereafter referred to as the UK-NA) are:



The partial safety factors will use the following values for the UK National Annex:




The design function in STAAD.Pro sets these values as the default values for the UK-NA (NA 1is specified).




Warning: 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 files thatuse GB1 parameter will indicate an error message and the user will need tosubstitute GB1 with GM1 in line with EN 1993-1-1:2005.

7D.1.2 Clause 6.3.2.2 –Elastic critical moment andimperfection factors for LTB checks

The UK-NA recommends the use of Table 6.3 and 6.4 of BS EN 1993-1-1:2005 to calculate theimperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor χLT, requires the calculation of the ‘ElasticCritical Buckling Moment’, Mcr. The UK National Annex does not specify a particularmethod to calculate Mcr. Hence the calculation of Mcr has been based on the following NCCIdocuments:

SN003a-EN-EU – Elastic critical moment for Lateral torsionalBuckling:

This document provides a method to calculate ‘Mcr’ specifically for doubly symmetricsections only. Hence only doubly symmetric sections will be considered for this method inthe proposed implementation.

The equation to evaluate Mcr is given in the NCCI as:

=

+ + −

M C C z C z( )cr

π EI

kL

k

k

I

I

kL GI

π EIs s1

( )

2( )

22

2s

w

w

s

t

s

2

2

2

2

C1 and C2 are factors that depend on the end conditions and the loading conditions of themember. The NCCI provides values for C1 and C2 for the different cases as given in the tablesbelow:

297— STAAD.Pro

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.


The implementation of EC3 in STAAD.Pro accounts for the loading condition and thebending moment diagram through the CMM parameter. The first two loading conditionsmentioned above and its variants can be dealt with by using the existing values of the CMMparameter (i.e., 1 to 6). Hence the appropriate values from this NCCI will be used for ‘C1’ and‘C2’ coefficients depending on the value of CMM specified. The default value of CMM is 1, whichconsiders the member as a pin ended member with UDL along its span. The user will alsohave the option to specify specific values for C1 and C2 using the C1 and C2 parameters in thedesign input mode. See "Design Parameters" on page 261

However, for cases with end moments and transverse loading, the NCCI provides graphs toevaluate the C1 and C2 coefficients. It does not however, provide a set of equations for thesegraphs. However the “end moments and transverse loading” condition cannot be currentlyspecified in the design input. Hence this implementation will introduce two new values forthe CMM parameter 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 not provide equationsto evaluate C1 and C2. Hence in STAAD.Pro the user will have to use the new ‘C1’ & ‘C2’parameters to input the required values for C1 & C2 to be used in calculating Mcr. For valuesof 7 or 8 for the CMM parameter, the program will issue a warning if C1 and C2 have not beenspecified.

Note: If the NA parameter has not been specified, the program obtains the values of C1and C2 from Annex F of DD ENV version of 1993-1-1:1992.

SN030a-EN-EU – Mono-symmetrical uniform members underbending and axial compression:

This document provides a method to evaluate the elastic critical moment (Mcr) for uniformmono symmetric sections that are symmetric about the weak axis. Hence for thisimplementation the elastic critical moment for ‘Tee-Sections’ will be worked out using themethod in this NCCI.

Note: Though this method could also be applicable to mono-symmetric built-up sections,STAAD.Pro currently does not have a means to specify/identify a mono-symmetric built-upsection. Hence this implementation will use this method only for Tee-Sections. In any case,the actual LTB capacity will still be worked out as per BS 5950-1 as in the current EC3implementation.

The equation to evaluate Mcr for mono symmetric sections is given as :

=

+ + − −

−

M C C z C z C z C z( )cr

π EI

k L

k

k

I

I

k L GI

π EIe e

( )

( )1

2

2 3 1

2

2 3 1s

x

x

w

w

s

x T

x

2

2

2

2

299— STAAD.Pro

The factors C1, C2, and C3 are dependent on the end conditions and loading criteria. Thisimplementation will consider C1, C2, and C3as given in the tables below:

The CMM parameter (see section (i) above) specified during design input will determine thevalues of C1, C2 and C3. The default value of CMM is 1, which considers the member as a pinended member with UDL along its span. This NCCI does not however consider the “endmoments and transverse loading” condition. The user however can use the new C1, C2 and C3parameters to input 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 parameters along with CMMvalues of 7 and 8.

Both the NCCI documents mentioned above assume that the member under consideration isfree to rotate on plan and that there are no warping restraints for the member ( k = kw = 1.0).The current implementation of EC3 in STAAD takes into account of the end conditions usingthe CMN parameter. A value of K = kw =1 is indicated by a value of CMN = 1.0 in the designinput. Hence the above methods will be used only for members which are free to rotate onplan and which have no warping restraints, i.e., CMN = 1.0. For members with partial or endfixities (ie, CMN = 0.5 or CMN = 0.7), the proposed implementation will fall back on to themethod and coefficients in DD ENV 1993-1-1:1992 – Annex F.

For all cases that are not dealt with by the National Annex (or the NCCI documents) theproposed 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 the point ofapplication of load on the cross section in relation to the shear center of the cross section.The value of ‘zg’ is considered positive if the load acts towards the shear center and isnegative if it acts away from the shear center. By default, the program will assume that theload acts towards the shear center at a distance equal to (Depth of section/2) from the shearcenter. 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 indicate that the load acts exactly atthe shear center of the section so that the term ‘zg’ in the equation will have a value of zero.

7D.1.3 Clause 6.3.2.3(1) – LTB for rolled sections orequivalent welded section

The UK-NA specifies different values for the λLT,0 and β factors to be used in equation 6.57 ofBS EN 1993-1-1 for rolled and equivalent welded sections. The current implementation inSTAAD.pro does not differentiate between rolled and welded sections and uses the defaultvalues in BS EN 1993-1-1 for λLT,0 and β. The values specified in the UK-NA are:

l For rolled sections and hot-rolled & cold formed hollow sections:

λLT,0 = 0.4

β = 0.75

l For welded sections:

λLT,0 = 0.2

β = 1.00

The current implementation of STAAD.Pro uses the buckling curves based on Table 6.5 of BSEN 1993-1-1:2005. The UK-NA specifies different limits and buckling curves to be used in thisclause as given below:

Cross Section Limits BucklingCurve

Rolled doubly symmetric I and H sectionsand hot-finished hollow sections

h/b ≤ 2 b

2.0 < h/b ≤ 3.1 c

h/b > 3.1 d

Angles (for moments in the major principle plane) d

All other hot-rolled sections d

Welded, doubly symmetric sections andcold-formed hollow sections

h/b ≤ 2 c

2.0 < h/b ≤ 3.1 d

Table 7D.1-Buckling curves to use with BS EN 1993-1-1:2005

This table again does not specify which buckling curve is to be used in case of welded doublysymmetric sections with h/b ≥ 3.1 and welded non-doubly symmetric sections. Hence for

301 — STAAD.Pro

these cases the new implementation will still use the method specified in the base code as perclause 6.3.2.2(2).

7D.1.4 Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTBReduction factor, χLT as per UK NA

Clauses 6.3.2.2 and 6.3.2.3 (EN 1993-1-1:2005), both give equations to evaluate the LTB reductionfactor χLT to 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 the imperfection factors tobe used for calculating χLT. Table 6.4 specifies the choice of buckling curves for “Rolled ISections”, “Welded I Sections” and “Any other sections”. Cl 6.3.2.3 on the other hand usestables 6.5 and 6.3 to choose the buckling curves and imperfection factors. Table 6.5 howeveronly 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 of constant crosssection the value of χLT should be determined from...”. Hence in the implementation of EC3(and the UK Annex) in STAAD.Pro, by default the program will consider clause Cl. 6.3.2.3 toevaluate χLT. 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 1993-1-1:2005 should bereplaced with the table given in the NA (See section 4.3 of this document). Hence for all casesdealt with by the table in the UK NA, this implementation will choose the buckling curvesfrom the UK National Annex. For any case that is not dealt with by the table in the UK NA,the program will use the method 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 NA forchoosing 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 toevaluate 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 or Cl.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 the UKNational Annex uses the NCCIs mentioned in the sections above, this implementation willonly consider end restraint conditions corresponding to the CMN parameter=1.0 (See section


4.2 above). 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 the design input= 0), the program will use Cl. 6.3.2.3 only in the case of Rolled or welded I & HSections. For all other cases, the program will use Cl. 6.3.2.2 of BS EN 1993-1-1:2005.Also, I sections with plates will be treated as built-up sections only if the sectionhas been explicitly specified as a built-up section (i.e., SBLT parameter = 1.0 indesign input).

7D.1.5 Clause 6.3.2.3(2) – Modification factor, f, for LTBchecks

The UK NA specifies the use of eqn. 6.58 of BS EN 1993-1-1:2005 to evaluate the modificationfactor ‘f’ for the LTB reduction factor χLT. To evaluate the modification factor BS EN 1993-1-1:2005 uses a correction factor ‘kc’ given by Table 6.6 in the code.

The UK-NA however, specifies that the correction factor ‘kc’ is to be obtained as below:

Kc = 1 / √C1, where C1 is to be obtained from the NCCI documents given in section 4.2 of thisdocument. The NCCI document SN003a-EN-EU specifies the values of C1 to be used in table3.1 as shown below. This proposed implementation will allow for the reduction factor basedon the UK-NA.

303— STAAD.Pro

These values are for an end restraint factor of k=1 (ie CMN=1.0). Hence for all other values ofCMN (ie 0.7 or 0.5) this implementation will use the values of C1 from DD ENV 1993-1-1:1992Annex F.

The program will use a default value of 1.0 for ‘kc’. However the user can also input a customvalue of ‘kc’ by setting the design parameter ‘KC’ to the desired value. The user can also getthe program to calculate the value of ‘kc’ automatically by setting the value of the ‘KC’parameter in the design input to 0. This will cause the program to evaluate a value of C1corresponding to the end conditions and the Bending moment of the member and in turncalculate ‘kc’ as given in the NA. To evaluate C1, the program will use the NCCI documentsmentioned in section 4.2 of this document.

7D.1.6 Clause 6.3.3(5) – Interaction factors kyy, kyz, kzy, andkzz

The UK-NA recommends that the method in Annex A or Annex B of BS EN 1993-1-1:2005 canbe used to calculate the interaction factors for Cl. 6.3.3 checks in the case of doubly symmetricsections. The proposed implementation will hence use equations in Annex B of BS EN 1993-1-1:2005 to calculate these interaction factors for doubly symmetric sections. The currentimplementation of EC3 BS in STAAD.pro uses the method in Annex B.

However for non-doubly symmetric sections, the UK NA gives the option of using Annex Bwith some modifications as given in the NA. (Cl. NA-3.2 of the UK NA). The UK NA requiresadditional checks to be done to check for the maximum allowable values of λ and X to be usedin 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 the weak axis (λyin STAAD) and the corresponding reduction factor χy should be taken as the values from thehighest values of slenderness (λ) among the flexural buckling slenderness (λy), torsionalslenderness (λT) and torsional-flexural slenderness (λTF) as given in Clauses 6.3.1.3 and 6.3.1.4 ofBS EN 1993-1-1:2005. Hence for non-doubly symmetric sections the program will calculate thecritical non-dimensional slenderness as:

λy = the maximum of either λ from Cl. 6.3.1.3 or λT from Cl. 6.3.1.4

=λTA f

N

y

cr

Where:

Ncr = min (NCrT, NcrTF).

The UK NA or EC3 does not however specify a method to evaluate NCrT or NcrTF. Hence thisimplementation will use the method specified in the NCCI document “SN001a-EN-EU:Critical axial load for torsional and flexural torsional buckling modes” to calculate these. Seesection 4.9 below for details.

Note: The UK National Annex or EC3 does not deal with angle sections in specific andhence this implementation will use the method used in the current EC3


implementation 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 anglesections to evaluate the slenderness.

Clause NA 3.2 of the UK NA also requires that “Where the section is not an I Section or ahollow section and is a class1 or class 2 section, it will be treated as a class 3 section for thepurposes of this clause”. Hence for all Class 1 or Class 2 cross sections that are NOT I, H, SHS,RHS or CHS sections, the elastic properties will be used for the purposes of 6.3.3 checks.

7D.1.7 Clause 6.3.1.4 - Slenderness for torsional andtorsional-flexural buckling

Equations 6.52 and 6.53 of BS EN 1993-1-1:2005 are to be used to calculate the non-dimensional slenderness λT, to be used for torsional and torsional-flexural buckling checks.BS EN 1993-1-1:2005 does not provide equations to calculate the elastic critical loads Ncr,T,Fand 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 flexural torsionalbuckling modes” provides methods to calculate the Ncr,TF and Ncr,T factors and thereforethese methods are used to evaluate the elastic critical loads for the UK NA.

The critical axial load for Torsional buckling is evaluated as:

=

+

N GIcr Ti

t

π EI

I,

1

o

w

T

2

2

2

Where:

= + + +i i i y zo y z o o2 2 2 2 2

iy and iz are the radius of gyration about the Y-Y (weak axis) and Z-Z (strongaxis) respectively.

The critical axial load for Torsional-Flexural buckling is evaluated as:

=

+ − + −

+

+N N N N N N N( ) 4cr TF

i

i icr y cr T cr y cr T cr y cr T

i i

i( ),2

, , , ,

2

, ,o

y z

y z

o

2

2 2

2 2

2

For details on these equations, refer to the NCCI document SN001a-EN-EU.

7D.2 French National Annex to EC3Adds values from the French National Annex - titled Annexe Nationale a la NF EN 1993-1-1:2005 - for use with Eurocode 3, or EN 1993-1-1:2005. The NA document makes small changesto the base document.


Clause 6.3.2.4(1) B – Slenderness for flexural buckling

305— STAAD.Pro

STAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the French National Annex.

Clause 6.3.2.4(2)B – Modification factor ‘kfl’STAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the French National Annex.

Note: Refer to the basic code (EC3) for a description of these clauses. The sections belowrefer to the corresponding clauses in the French-NA.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that have been dealtwith in the French National Annex (hereafter referred to as FR-NA) and that are relevant tothe proposed implementation are:

7D.2.1 Clause 3.2.1(1) - Material Properties

The material strengths (i.e., - steel grade strengths) to be used with NF EN 1993-1-1 are given inTable 3.1 of the code. The French National Annex however, specifies a separate table (Table 3.1NF) for the yield and tensile strengths of steel grades. This new table replaces Table 3.1 in NFEN 1993-1-1:2005. Table 3.1 NF excludes steel grades from standards EN 10210-1 and EN 10219-1that are given in EC-3.

STAAD.Pro uses the steel grades and values from the table given in the National Annex (i.e., -Table 3.1 NF). Table 3.1 NF is similar to table 3.1 in EC3, apart from the fu values for S 355 andS355 W grade steel.

Standard and grade ofsteel

Nominal thickness, t, of the element(mm)

t 40 mm40 mm < t <= 80

mm

fy

(N/mm2)

fu

(N/mm2)

fy

(N/mm2)

fu

(N/mm2)

EN 10025-2

S 235 235 360 215 360

S 275 275 430 255 410

S 355 355 490 335 470

S 450 440 550 410 550

Table 7D.2-Material strengths specified for use with the NF-NA


Standard and grade ofsteel

Nominal thickness, t, of the element(mm)

t 40 mm40 mm < t <= 80

mm

fy

(N/mm2)

fu

(N/mm2)

fy

(N/mm2)

fu

(N/mm2)

EN 10025-3

S 275 N/NL 275 390 255 370

S 355 N/NL 355 490 335 470

S 420 N/NL 420 520 390 520

S 460 N/NL 460 540 430 540

EN 10025-4

S 275 M/ML 275 370 255 360

S 355 M/ML 355 470 335 450

S 420 M/ML 420 520 390 500

S 460 M/ML 460 540 430 530

EN 10025-5

S 235 W 235 360 215 340

S 355 W 355 490 335 490

EN 10025-6

S 460Q/QL/QL 1

460 570 440 550

If you specify a steel grade that is not given in the Annex Table 3.1 (NF) but is present inTable 3.1 of EN 1993-1-1:2005, the program uses the values from Table 3.1 of EN 1993-1-1:2005.The appropriate yield strength (fy) used is shown in the design output file.

7D.2.2 Clause 6.1(1) – General


The partial safety factors will use the following values for the French National Annex:




The design function in STAAD.Pro sets these values as the default values for the NF-NA (NA4 is specified).

307— STAAD.Pro





The French NA recommends the use of Table 6.3 and 6.4 of NF EN 1993-1-1:2005 to calculatethe imperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor χLT, requires the calculation of the “Elastic CriticalBuckling Moment”, Mcr. The French NA gives a method to evaluate Mcr in its “Annex MCR”.This implementation will make use of this method to evaluate Mcr. Annex MCR however dealswith the calculation of Mcr for doubly symmetric sections. Hence this implementation willuse this method only for doubly symmetric sections. For mono symmetric sections that aresymmetric about the minor axis (i.e Tee sections) this implementation will use the methodfrom the NCCI document SN030a-EN-EU as given in the section below. For any other type ofsection that is not dealt with by the Annex, this implementation will use the method andtables given in Annex F of DD ENV 1993-1-1:1992.

Annex MCR

This document provides a method to calculate Mcr specifically for doubly symmetric sectionsonly. Hence only doubly symmetric sections will be considered for this method in thisimplementation.

The equation to evaluate Mcr is given as:

=

+ + −

M C C z C z( )cr

π EI

kL

k

k

I

I

kL GI

π EIs s1

( )

2( )

22

2s

w

w

s

t

s

2

2

2

2

C1 and C2 are factors that depend on the end conditions and the loading conditions. TheNCCI provides values for C1 and C2 for the different cases as given in Table1 and Table 2 of theAnnex. Table 1 deals with the condition of a simply supported member with end moments andthe value of C1 is determined 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:


=+ +

Cψ ψ

1

1

0.325 0.423 0.2522

This formula however does not match the values given in Table 1 of the NA. Hence thisimplementation will use the values of C1 from Table 1 if the end moment ration (ψ) is exactlyequal to the values of ψ in the table. For all other cases this implementation will calculate thevalue of C1 from equation (6) in the Annex.

The value of C2 will be determined from Table 2 of the Annex based on the loading and endconditions (i.e the CMM parameter in STAAD).

The user will also have the option to specify specific values for C1 and C2 using the C1 and C2parameters in the design input mode. See "Design Parameters" on page 261

The French NA considers three separate loading conditions:




The first two cases and its variants can be defined using with the existing CMM parametervalues in STAAD.Pro. However the third condition cannot be currently specified in thedesign input. Hence this implementation will introduce 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 be used tocalculate C1 and C2 as given in section 3.5 of Annex MCR (See Annex MCR in the NA fordetails).

This implementation will also introduce a new parameter ‘MU’ to be specified when usingCMM = 7 or 8. The load to moment ratio (μ) to be used in the calculations is to be inputusing the new ‘MU’ parameter. This implementation will require that for the French NationalAnnex if CMM = 7 or 8 has been specified, the user should also either specify a value for ‘MU’or input the values for C1 and C2 using the ‘C1’ and/or ‘C2’ parameters directly.

Note: The new parameter MU will currently be applicable only in the context of theFrench NA.


This document provides a method to evaluate the elastic critical moment (Mcr) for uniformmono symmetric sections that are symmetric about the weak axis. Hence for thisimplementation the elastic critical moment for ‘Tee-Sections’ will be worked out using themethod in this NCCI.

309— STAAD.Pro

Note: Though this method could also be applicable to mono-symmetric built-up sections,STAAD.Pro currently does not have a means to specify/identify a mono-symmetricbuilt-up section. Hence this implementation will use this method only for Tee-Sections.

The equation to evaluate Mcr for mono symmetric sections is given as:

=

+ + − −

−


π EI

k L

k

k

I

I

k L GI

π EIe e

( )

( )1

2

2 3 1

2

2 3 1s

x

x

w

w

s

x T

x

2

2

2

2

The factors C1, C2, and C3are dependent on the end conditions and loading criteria. Thisimplementation will consider C1, C2, and C3as given in the tables below:

The CMM parameter specified during design input will determine the values of C1, C2 and C3.The default value of CMM is 0, which considers the member as a pin ended member withUDL along its span. This NCCI does not however consider the “end moments and transverseloading” condition. The user however can use the new ‘C1’, ‘C2’ and ‘C3’ parameters to inputthe required 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 program will ignore MUand use the user input values of C1, C2 and C3. The current implementation of EC3in STAAD.Pro obtains these values from Annex F of DD ENV version of 1993-1-1:1992.

Also, the NCCI document and Annex MCR of the FR-NA assume that the member underconsideration is free to rotate on plan and that there are no warping restraints for themember( k = kw=1 .i.e., CMN parameter =1.0). Hence the above methods will be used only formembers which are free to rotate on plan and which have no warping restraints. For memberswith partial or end fixities (ie, CMN = 0.5 or CMN = 0.7), this implementation will fall backon to the method and coefficients in DD ENV 1993-1-1:1992.

For all cases that are not dealt with by the National Annex (or the NCCI documents) thisimplementation 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 the point ofapplication of load on the cross section in relation to the shear center of the cross section.The value of ‘zg’ is considered positive, if the load acts towards the shear center and isnegative if it acts away from the shear center. By default, the program will assume that theload acts towards the shear center at a distance equal to (Depth of section/2) from the shearcenter. The use will be allowed to modify this value by using the ZG parameter. Specifying avalue of ZG = 0 in the design input would indicate that the load acts exactly at the shearcenter of the section 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” tocalculate Mcr for cantilever beams. Again this document does not give any specificformulae to evaluate the coefficients. Hence, this has not been implemented inSTAAD.Pro.


The FR-NA provides equations to evaluate the λLT,0 and αLT factors given in clause 6.3.2.3

For rolled doubly symmetric sections use:

= +λ 0.2 0.1LT

b

h, 0

= − ≥α λ0.4 0.2 0LT

b

hLT

2

Note: Since EN 1993-1-1:2005 limits the value of λLT,0 to 0.4, STAAD.Pro limits λLT,0 to amaximum value of 0.4.

For welded doubly symmetric sections use:

=λ 0.3LT

b

h, 0

311 — STAAD.Pro

= − ≥α λ0.5 0.25 0LT

b

hLT

2

For other sections:

λLT,0 = 0.2

αLT = 0.76

And for all sections, β = 1.0

These equations and factors are then applied to equation 6.57 of NF EN 1993-1-1 to evaluate theLateral Torsional Buckling reduction factor χLT.


The French NA specifies that the modification factor is to be obtained as per the defaultmethod given in EC-3. Hence this implementation will use the existing functionality toevaluate the correction factor kc to be used in the modification factor f.

The program uses a default value of 1.0 for kc. However the user can also input a custom valueof kc by setting the design parameter KC to the desired value. You may instruct the program tocalculate the value of kc automatically by setting the value of the KC parameter in the designinput to 0. This will cause the program to evaluate kc from Table 6.6 of NF EN 1993-1-1:2005.This will correspond 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 the value of kc to be either 0.90 or 0.91 based on the endmoment ratio.

For CMM = 8, the program will choose the value of kc to be either 0.77 or 0.82 based on the endmoment ratio.

An additional check will also be performed as given below:

≤χLT

λ,mod

1

LT

2

The French Annex specifies that the modification factor is applicable only to members that arefree to rotate on plan (i.e., CMN 1.0). Hence for all other values of CMN, this implementationwill ignore ‘f’ and hence will use χLT,mod = χLT.


The French NA recommends the use of equations in Annex A of NF EN 1993-1-1:2005 tocalculate these interaction factors. STAAD.pro uses the method in Annex B for design per EC3(without National Annex). Therefore, the method in Annex A has been added into theprogram.


Note: 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 insteadof the plastic properties. However, since STAAD does not have a provision to specifysuch sections, this case will not be considered for this implementation.

The NA also mentions that torsional flexural buckling needs to be taken into account in caseof mono symmetric sections. This is taken into account based on the method given in theNCCI document “SN001a-EN-EU: Critical axial load for torsional and flexural torsionalbuckling modes”. See "Clause 6.3.1.4 - Slenderness for torsional and torsional-flexuralbuckling" on page 313

The NA also recommends a lower limit as given below for the term Cmi,0 in Table A.2 ofAnnex A:

≥ −C 1mi

N

N, 0

Ed

cr i,


Equations 6.52 and 6.53 of NF EN 1993-1-1:2005 are to be used to calculate the non-dimensional slenderness λT, to be used for torsional and torsional-flexural buckling checks.NF EN 1993-1-1:2005 does not provide equations to calculate the elastic critical loads Ncr,T,Fand 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 flexural torsionalbuckling modes” provides methods to calculate the Ncr,TF and Ncr,T factors and thereforethese methods are used to evaluate the elastic critical loads for the French NA.


=

+

N GIcr Ti

t

π EI

I,

1

o

w

T

2

2

2

Where:

= + + +i i i y zo y z o o2 2 2 2 2



=

+ − + −

+


i


i i

i( ),2

, , , ,

2

, ,o

y z

y z

o

2

2 2

2 2

2


313— STAAD.Pro

7D.3 Finnish National Annex to EC3Adds values from the Finnish National Annex - titled National Annex to Standard SFS-EN1993-1-1 - for use with Eurocode 3, or EN 1993-1-1:2005. The NA document makes small changesto the base document.


Clause 6.3.2.4(1) B – Slenderness for flexural bucklingSTAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Finnish National Annex.

Clause 6.3.2.4(2)B – Modification factor ‘kfl’STAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Finnish National Annex.

Note: Refer to the basic code (EC3) for a description of these clauses. The sections belowrefer to the corresponding clauses in the Finnish-NA.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that have been dealtwith in the Finnish National Annex (hereafter referred to as SFS-NA) and that are relevant tothe proposed implementation are:


The material strengths (i.e., steel grade strengths) to be used with SFS-EN 1993-1-1 are given inTable 3.1 of the code. These steel grade values are specified using the SGR parameter (See"Design Parameters" on page 261).

The Finnish National Annex states in Cl. 3.1(2) that, apart from the steel grades specified inTable 3.1 of SFS EN 1993-1-1, the following steel grades can also be used:

l Steel grades S315MC, S355MC, S420MC and S460MC according to SFS-EN 10149-2

l Steel grades S260NC, S315NC, S355NC and S420NC according to SFS-EN 10149-3

These grades of steel can be specified by using the PY (Yield Strength) and FU (UltimateStrength) parameters in STAAD.Pro. Set these parameters to the respective values as given inSFS-EN 10149-2/3 for the steel grades specified above. The choice of the buckling curve to beused is based on the value of the SGR parameter specified. The output will include theappropriate yield strength used for design.



The partial safety factors will use the following values for the Finnish National Annex:





The design function in STAAD.Pro sets these values as the default values for the SFS-NA (NA5 is specified).





The Finnish NA recommends the use of Table 6.3 and 6.4 of SFS EN 1993-1-1:2005 to calculatethe imperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor χLT, requires the calculation of the ‘ElasticCritical Buckling Moment’, Mcr. The Finnish National Annex does not specify a particularmethod to calculate Mcr. Hence the calculation of Mcr has been based on the following NCCIdocuments:

1. SN003a-EN-EU – Elastic critical moment for Lateral torsionalBuckling:

This document provides a method to calculate Mcr specifically for doubly symmetricsections only. Hence only doubly symmetric sections will be considered for thismethod. The equation to evaluate Mcr is given in the NCCI as:

=

+ + −

M C C z C z( )cr

π EI

kL

k

k

I

I

kL GI

π EIs s1

( )

2( )

22

2s

w

w

s

t

s

2

2

2

2

C1 and C2 are factors that depend on the end conditions and the loading conditions ofthe member. The NCCI provides values for C1 and C2 for the different cases as given inthe tables below:

315— STAAD.Pro

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 7D.3-Values of C1 for endmoment loading (for k=1)





STAAD.Pro accounts for the loading condition and the bending moment diagramthrough the CMM parameter.

2. SN030a-EN-EU – Mono-symmetrical uniform members underbending and axial compression:

This document provides a method to evaluate the elastic critical moment (Mcr) foruniform mono symmetric sections that are symmetric about the weak axis. Hence, theelastic critical moment for ‘Tee-Sections’ will be worked out using the method in thisNCCI.

Note: Though this method could also be applicable to mono-symmetric built-upsections, STAAD.Pro currently does not have a means to specify/identify amono-symmetric built-up section. Hence this implementation will use thismethod only for Tee-Sections.



=

+ + − −

−


π EI

k L

k

k

I

I

k L GI

π EIe e

( )

( )1

2

2 3 1

2

2 3 1s

x

x

w

w

s

x T

x

2

2

2

2

The factors C1, C2, and C3 are dependent on the end conditions and loading criteria.This implementation will consider C1, C2, and C3 as given in the tables below:

The CMM parameter specified during design input will determine the values of C1, C2,and C3. The default value of CMM is 0, which considers the member as a pin endedmember with UDL along its span. This NCCI does not however consider the “endmoments and transverse loading” condition. You can use the C1, C2, and C3parameters to input the required values for C1, C2, and C3 to be used in calculatingMcr.

Note: If MU as well as C1, C2, and C3 have been specified, the program will ignoreMU and use the user input values of C1, C2, and C3. STAAD.Pro obtains thesevalues from Annex F of DD ENV version of 1993-1-1:1992.

Both the NCCI documents mentioned above assume that the member under consideration isfree to rotate on plan and that there are no warping restraints for the member ( k = kw = 1.0).STAAD.Pro takes into account of the end conditions using the CMN parameter for EC3. Avalue of K = kw =1 is indicated by a value of CMN = 1.0 in the design input. Hence the above

317— STAAD.Pro

methods will be used only for members which are free to rotate on plan and which have nowarping restraints (i.e., CMN = 1.0). For members with partial or end fixities (i.e., CMN = 0.5 orCMN = 0.7), this implementation will fall back on to the method and coefficients in DD ENV1993-1-1:1992 – Annex F.


The term ‘zg’ in the equation to calculate Mcr refers to the distance between the point ofapplication of load on the cross section in relation to the shear center of the cross section. Thevalue of ‘zg’ is considered positive, if the load acts towards the shear center and is negative if itacts away from the shear center. By default, the program will assume that the load actstowards the shear center at a distance equal to (Depth of section/2) from the shear center. Theuse will be allowed to modify this value by using the ZG parameter. Specifying a value of ZG =0 in the design 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.



The Finnish-NA provides the values for the terms λLT,0 and β factors given in clause 6.3.2.3(1)as follows:

For rolled doubly symmetric sections and hollow sections, use:

λLT,0 =0.4 and β = 0.75

For welded doubly symmetric sections and hollow sections use:

λLT,0 = 0.2 and β = 1.0

The Finnish NA specifies the following limits for choosing the buckling curves:


Cross-section

(constant cross-section)

Lim-its

Buck-lingCurve

Rolled double symmetric I- and H- sections and hotfinished hollow sections.

h/b ≤2

2 <h/b<3.1

b

c

Welded double symmetric I- section and H- sectionsand cold-formed hollow sections

h/b ≤2

2 <h/b <3.1

c

d

Table 7D.4-Selection of lateral torsional buckling curve for cross sectionsusing equation (6.57)

The NA says that for all other cases the rules given in Cl 6.3.2.2 should be used. Hence evenfor rolled or welded doubly symmetric sections with h/b ratio ≥ 3.1, this implementation willresort to checks as per clause 6.3.2.2.

These equations and factors are then applied to equation 6.57 of SFS-EN 1993-1-1 to evaluatethe Lateral Torsional Buckling reduction factor χLT.

7D.3.5 Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTBReduction 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 evaluate the LTBreduction factor χLT to be used in eqn. 6.55 of SFS EN 1993-1-1:2005.


Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending members of constant crosssection the value of χLT should be determined from...”. Hence in the implementation of EC3(and the Finnish Annex) in STAAD.Pro: by default the program will consider clause Cl. 6.3.2.3to evaluate χLT. 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 the imperfection factorsto be used for various section types (See "Clause 6.3.2.2 –Elastic critical moment andimperfection factors for LTB checks" on page 315 ). Hence for all cases dealt with by theequations in the Finnish NA, this implementation will use Cl 6.3.2.3 to evaluate χLT.

319— STAAD.Pro


In any case, the elastic critical moment, Mcr, (used to evaluate the non dimensionalslenderness) will be evaluated as previously given. Since this implementation uses the NCCIsmentioned in the sections above, only end restraint conditions corresponding to the CMNparameter=1.0 (See "Clause 6.3.2.2 –Elastic critical moment and imperfection factors for LTBchecks" on page 315 ) will be considered. For all other cases of the CMN parameter values, thisimplementation will use the method 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 the design input =0), the program will use Cl. 6.3.2.3 only in the case of Rolled or welded I & HSections. For all other cases, the program will use Cl. 6.3.2.2 of BS EN 1993-1-1:2005.Also, I sections with plates will be treated as built-up sections only if the section hasbeen explicitly specified as a built-up section (i.e., SBLT parameter = 1.0 in designinput).


STAAD.Pro uses the value of the modification factor f = 1.0 as given in the Finnish NA.


The Finnish NA recommends the use of equations in Annex A or Annex B of SFS-EN 1993-1-1to calculate these interaction factors. STAAD.Pro uses the method in Annex B by default. Thisimplementation of the Finnish NA will also use Annex B for Cl.6.3.3 checks.


Equations 6.52 and 6.53 of SFS EN 1993-1-1:2005 are to be used to calculate the non-dimensional slenderness λT, to be used for torsional and torsional-flexural buckling checks.SFS EN 1993-1-1:2005 does not provide equations to calculate the elastic critical loads Ncr,T,Fand 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 flexural torsionalbuckling modes” provides methods to calculate the Ncr,TF and Ncr,T factors and thereforethese methods are used to evaluate the elastic critical loads for the Finnish NA.


=

+

N GIcr Ti

t

π EI

I,

1

o

w

T

2

2

2

Where:

= + + +i i i y zo y z o o2 2 2 2 2




=

+ − + −

+


i


i i

i( ),2

, , , ,

2

, ,o

y z

y z

o

2

2 2

2 2

2


7D.4 Polish National Annex to EC3Adds values from the Polish National Annex - titled National Annex to Standard PN-EN1993-1-1 - for use with Eurocode 3, or EN 1993-1-1:2005. The NA document makes smallchanges to the base document.


Clause 6.3.2.4(1) B – Slenderness for flexural bucklingSTAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Polish National Annex.

Clause 6.3.2.4(2)B – Modification factor ‘kfl’STAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Polish National Annex.

Note: Refer to the basic code (EC3) for a description of these clauses. The sections belowrefer to the corresponding clauses in the Polish-NA.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that have been dealtwith in the Polish National Annex (hereafter referred to as PN-NA) and that are relevant tothe proposed implementation are:


The material strengths (i.e., steel grade strengths) to be used with PN-EN 1993-1-1 are given inTable 3.1 of the code. The Polish National Annex states in Cl. 3.1(2) that the steel grades to beused will be based on Table 3.1 of PN EN 1993-1-1. These steel grade values are specified usingthe SGR parameter (See "Design Parameters" on page 261).



The partial safety factors will use the following values for the Polish National Annex:



l Resistance of cross sections to tension, γM2 = minimum of 1.1 or 0.9 x fu/fy

321 — STAAD.Pro

Where:

fu is the ultimate steel strength

fy is the yield strength of steel

The design function in STAAD.Pro sets these values as the default values for the PN-NA (NA 6is specified).





The Polish NA recommends the use of Table 6.3 and 6.4 of PN EN 1993-1-1:2005 to calculatethe imperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor χLT, requires the calculation of the ‘Elastic CriticalBuckling Moment’, Mcr. The Polish National Annex does not specify a particular method tocalculate Mcr. Hence the calculation of Mcr has been based on the following NCCI documents:

1. SN003a-EN-EU – Elastic critical moment for Lateral torsionalBuckling:

This document provides a method to calculate Mcr specifically for doubly symmetricsections only. Hence only doubly symmetric sections will be considered for thismethod. The equation to evaluate Mcr is given in the NCCI as:

=

+ + −

M C C z C z( )cr

π EI

kL

k

k

I

I

kL GI

π EIs s1

( )

2( )

22

2s

w

w

s

t

s

2

2

2

2

C1 and C2 are factors that depend on the end conditions and the loading conditions ofthe member. The NCCI provides values for C1 and C2 for the different cases as given inthe tables below:


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






STAAD.Pro accounts for the loading condition and the bending moment diagramthrough the CMM parameter.

2. SN030a-EN-EU – Mono-symmetrical uniform members underbending and axial compression:

This document provides a method to evaluate the elastic critical moment (Mcr) foruniform mono symmetric sections that are symmetric about the weak axis. Hence, theelastic critical moment for ‘Tee-Sections’ will be worked out using the method in thisNCCI.

Note: Though this method could also be applicable to mono-symmetric built-upsections, STAAD.Pro currently does not have a means to specify/identify amono-symmetric built-up section. Hence this implementation will use thismethod only for Tee-Sections.


323— STAAD.Pro

=

+ + − −

−


π EI

k L

k

k

I

I

k L GI

π EIe e

( )

( )1

2

2 3 1

2

2 3 1s

x

x

w

w

s

x T

x

2

2

2

2

The factors C1, C2, and C3 are dependent on the end conditions and loading criteria.This implementation will consider C1, C2, and C3 as given in the tables below:

The CMM parameter specified during design input will determine the values of C1, C2,and C3. The default value of CMM is 0, which considers the member as a pin endedmember with UDL along its span. This NCCI does not however consider the “endmoments and transverse loading” condition. You can use the C1, C2, and C3 parametersto input the required 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 program will ignore MUand use the user input values of C1, C2, and C3. STAAD.Pro obtains thesevalues from Annex F of DD ENV version of 1993-1-1:1992.

Both the NCCI documents mentioned above assume that the member under consideration isfree to rotate on plan and that there are no warping restraints for the member ( k = kw = 1.0).STAAD.Pro takes into account of the end conditions using the CMN parameter for EC3. A valueof K = kw =1 is indicated by a value of CMN = 1.0 in the design input. Hence the abovemethods will be used only for members 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 = 0.5or CMN = 0.7), this implementation will fall back on to the method and coefficients in DDENV 1993-1-1:1992 – Annex F.


The term ‘zg’ in the equation to calculate Mcr refers to the distance between the point ofapplication of load on the cross section in relation to the shear center of the cross section.The value of ‘zg’ is considered positive, if the load acts towards the shear center and isnegative if it acts away from the shear center. By default, the program will assume that theload acts towards the shear center at a distance equal to (Depth of section/2) from the shearcenter. The use will be allowed to modify this value by using the ZG parameter. Specifying avalue of ZG = 0 in the design input would indicate that the load acts exactly at the shearcenter of the section so that the term ‘zg’ in the equation will have a value of zero.



The Polish-NA provides the values for the terms λLT,0 and β factors given in clause 6.3.2.3(1)as follows:

For all sections, use:

λLT,0 =0.4 and β = 0.75

The Polish NA specifies the use of uses table 6.5 to work out the buckling curves for 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 1993-1-1 to evaluatethe Lateral Torsional Buckling reduction factor χLT.

7D.4.5 Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTBReduction 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 evaluate the LTBreduction factor χLT to be used in eqn. 6.55 of PN EN 1993-1-1:2005.


325— STAAD.Pro

Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending members of constant crosssection the value of χLT should be determined from...”. Hence in the implementation of EC3(and the Finnish Annex) in STAAD.Pro: by default the program will consider clause Cl. 6.3.2.3to evaluate χLT. 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 the imperfection factors tobe used for various section types (See "Clause 6.3.2.2 –Elastic critical moment and imperfectionfactors for LTB checks" on page 315 ). Hence for all cases dealt with by the equations in theFinnish NA, this implementation will use Cl 6.3.2.3 to evaluate χLT.


In any case, the elastic critical moment, Mcr, (used to evaluate the non dimensionalslenderness) will be evaluated as previously given. Since this implementation uses the NCCIsmentioned in the sections above, only end restraint conditions corresponding to the CMNparameter=1.0 (See "Clause 6.3.2.2 –Elastic critical moment and imperfection factors for LTBchecks" on page 315 ) will be considered. For all other cases of the CMN parameter values, thisimplementation will use the method specified in Annex F of DD ENV 1993-1-1:1992.



STAAD.Pro uses the value of the modification factor f as per eqn 6.58 of PN-EN 1993-1-1. Thecorrection factor ‘kc’ will be evaluated as:

kc = √(CmLT)

Where:

CmLT is the equivalent uniform moment factor from table B.3 of PN-EN 1993-1-1.CmLT is evaluated based on the end conditions of the member and the shape ofthe bending moment diagram. However, if the KC parameter has been used, thenthe program will use the specified value.


The Polish NA recommends the equations in Annex B of PN-EN 1993-1-1 to calculate theseinteraction factors. The current implementation of EC3 BS in STAAD.pro uses the method in


Annex B by default. The proposed implementation of the Polish NA will also use Annex B forCl.6.3.3 checks.

The Polish NA also gives two additional simplified checks. This implementation will providefor these additional checks as well. However as they are intended as optional checks, bydefault, the program will not perform these checks. However, the user can invoke thesechecks by using the PLG parameter. See "Design Parameters" on page 261

If the value of the PLG parameter is set to 1, the following two checks will be performed as perCl. NA.20.(2) and NA.20(3) respectively:

l Cl. NA.20.(2): The following condition will be checked

n/ χ and + Cmy my/ χLT + C mz m with ≤ 1- Δ0 (I = y or z)

Where:

n = NEd/NRdmy = max My,Ed (+ Δ My, Ed)/My, Rd; mz = max M,Z Ed (+ Δ M , Ed)/MZ 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 beworked out as:

Δ0 = 0,1 + 0,2 (wi – 1), przy czym wi = Wpl,i/Wel,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 hollow sections.

n/χi + [(kii mi)2 + (Cmj mj)

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 ratios will betaken 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 ignore the last twochecks in the list above.

327— STAAD.Pro


Equations 6.52 and 6.53 of PN EN 1993-1-1:2005 are to be used to calculate the non-dimensionalslenderness λT, to be used for torsional and torsional-flexural buckling checks. PN EN 1993-1-1:2005 does not provide equations to calculate the elastic critical loads Ncr,T,F and Ncr,T (refer6.3.14 of PN EN 1993-1-1:2005).

The NCCI document “SN001a-EN-EU: Critical axial load for torsional and flexural torsionalbuckling modes” provides methods to calculate the Ncr,TF and Ncr,T factors and thereforethese methods are used to evaluate the elastic critical loads for the Polish NA.


=

+

N GIcr Ti

t

π EI

I,

1

o

w

T

2

2

2

Where:

= + + +i i i y zo y z o o2 2 2 2 2



=

+ − + −

+


i


i i

i( ),2

, , , ,

2

, ,o

y z

y z

o

2

2 2

2 2

2


7D.5 Singaporean National Annex to EC3Adds values from the Singaporean National Annex - titled National Annex to Standard SS-EN1993-1-1 - for use with Eurocode 3, or EN 1993-1-1:2005. The NA document makes small changesto the base document.

Note: Refer to the basic code (EC3) for a description of these clauses. The sections belowrefer to the corresponding clauses in the Singaporean-NA.


Clause 6.3.2.4(1) B – Slenderness for flexural bucklingThe SINGAPORE NA specifies the value of λc0 for I, H channel or box section to beused in equation 6.59 of SS EN 1993-1-1:2005 as 0.4. However, STAAD.Pro does notuse this clause for design per EC-3. Therefore, this clause is ignored for theSingaporean National Annex.


Clause 6.3.2.4(2)B – Modification factor ‘kfl’The value of the modification factor kfl to be used in equation 6.60 of SS EN 1993-1-1. However, STAAD.Pro does not use this clause for design per EC-3. Therefore,this clause is ignored for the Singaporean National Annex.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that have been dealtwith in the Singaporean National Annex (hereafter referred to as SS-NA) and that are relevantto the proposed implementation are:

7D.5.1 Clause 6.1 – General





The design function in STAAD.Pro sets these values as the default values for the SS-NA (NA 7is specified)..


Note: If any of these parameters have been specified by the user as ‘0’, STAAD.Pro willignore the specified value and use the default values as given above.


The Singaporean NA recommends the use of Table 6.3 and 6.4 of NF 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 ‘ElasticCritical Buckling Moment’, Mcr. The Singaporean National Annex does not specify aparticular method to calculate Mcr. Hence the calculation of Mcr has been based on thefollowing NCCI documents:

SN003a-EN-EU – Elastic critical moment for Lateral torsionalBuckling

This document provides a method to calculate ‘Mcr’ specifically for doubly symmetricsections only. Hence only doubly symmetric sections will be considered for this method. Theequation to evaluate Mcr is given in the NCCI as:

=

+ + −

M C C Z C Z( )cr

π EI

kL

k

k

I

I

kL GI

π EIg g1

( )

2( )

2

2

2w

w t2

2

2

2

329— STAAD.Pro

C1 and C2 are factors that depend on the end conditions and the loading conditions of themember. The NCCI provides values for C1 and C2 for the different cases as given in the tablesbelow:

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






STAAD.Pro accounts for the loading condition and the bending moment diagram throughthe CMM parameter.


This document provides a method to evaluate the elastic critical moment (Mcr) for uniformmono symmetric sections that are symmetric about the weak axis. Hence, the elastic criticalmoment for ‘Tee-Sections’ will be evaluated using the method in this NCCI.




=

+ + − − −


π EI

k L

k

k

I

I

k L GI

π EIg g

( )

( )1

2

2 3 1

2

2 3 1z

x

x

w

w x T

z

2

2

2

2

The factors C1, C2 and C3 are dependent on the end conditions and loading criteria. Thisimplementation will consider C1, C2 and C3 as given in the tables below:

The CMM parameter specified during design input will determine the values of C1, C2 andC3. The default value of CMM is 0, which considers the member as a pin ended member withUDL along its span. This NCCI does not however consider the “end moments and transverseloading” condition. The user however can use the new ‘C1’, ‘C2’ and ‘C3’ parameters to inputthe required 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 program will ignore MUand use the user input values of C1, C2 and C3. STAAD.Pro obtains these valuesfrom Annex F of DD ENV version of 1993-1-1:1992.

Both the NCCI documents mentioned above assume that the member under consideration isfree to rotate on plan and that there are no warping restraints for the member ( k = kw = 1.0).STAAD.Pro takes into account of the end conditions using the CMN parameter for EC3. A

331 — STAAD.Pro

value of K = kw =1 is indicated by a value of CMN = 1.0 in the design input. Hence the abovemethods will be used only for members which are free to rotate on plan and which have nowarping restraints (i.e., CMN = 1.0). For members with partial or end fixities (i.e., CMN = 0.5 orCMN = 0.7), this implementation will fall back on to the method and coefficients in DD ENV1993-1-1:1992 – Annex F.





The Singaporean NA specifies different values for the λLT,0 and β factors to be used in equation6.57 of SS EN 1993-1-1 for rolled and equivalent welded sections. STAAD.Pro does notdifferentiate between rolled and welded sections and uses the default values in SS EN 1993-1-1for λLT,0 and β. The values specified in the Singapore NA are:

l For rolled sections and hot-rolled & cold formed hollow sections:

λLT,0 = 0.4

β = 0.75

l For welded sections:

λLT,0 = 0.2

β = 1.00

STAAD.Pro uses the buckling curves based on Table 6.5 of SS EN 1993-1-1:2005. TheSingaporean-NA provides the values for the terms λLT0 and β factors given in clause 6.3.2.3(1)as follows:


Cross Section Limits BucklingCurve

Rolled doubly symmetric I and H sectionsand hot-finished hollow sections

h/b ≤ 2 b

2.0 < h/b ≤ 3.1 c

h/b > 3.1 d

Angles (for moments in the major principle plane) d

All other hot-rolled sections d

Welded, doubly symmetric sections andcold-formed hollow sections

h/b ≤ 2 c

2.0 < h/b ≤ 3.1 d

Table 7D.7-Buckling curves to use with SS-EN 1993-1-1:2005

Note: This table does not specify which buckling curve is to be used in case of weldeddoubly symmetric sections with h/b ≥ 3.1 and welded non-doubly symmetricsections. Hence for these cases the new implementation will still use the methodspecified in the base code as per clause 6.3.2.2(2).

7D.5.4 Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTBReduction factor, χLT as per Singaporean NA

Clauses 6.3.2.2 and 6.3.2.3 (EN 1993-1-1:2005) both give equations to evaluate the LTB reductionfactor χLT to be used in eqn. 6.55 of SS EN 1993-1-1:2005.


Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending members of constant crosssection the value of χLT should be determined from...”. Hence in the implementation of EC3(and the Singaporean Annex) in STAAD.Pro: by default the program will consider clause Cl.6.3.2.3 to evaluate χLT. For any case that is not dealt with by Cl. 6.3.2.3, the program willconsider Cl. 6.3.2.2 to evaluate χLT.

Cl. 6.3.2.3 in the Singaporean National Annex states that Table 6.5 in SS EN 1993-1-1:2005should be replaced with the table given in the NA (See section 4.3 of this document). Hencefor all cases dealt with by the table in the Singaporean NA, this implementation will choosethe buckling curves from the Singaporean National Annex. For any case that is not dealt withby the table in the Singaporean NA, the program will use the method given in Cl. 6.3.2.2 of SSEN 1993-1-1:2005.

For the following cross sections, the program will use the Table in the Singaporean NA forchoosing a buckling curve for LTB checks (when the SS EN has been specified):

333— STAAD.Pro



l Angle Sections



For the following cross sections, the program will use Cl. 6.3.2.3 of SS EN 1993-1-1:2005 toevaluate χLT



In any case, the elastic critical moment, Mcr, (used to evaluate the non dimensionalslenderness) will be evaluated as given above. Since this implementation uses the NCCIsmentioned in the sections above, only end restraint conditions corresponding to the CMNparameter=1.0 (See section above) will be considered. For all other cases of the CMN parametervalues, this implementation will use the method specified in Annex F of DD ENV 1993-1-1:1992.



The Singaporean NA specifies the use of Equation 6.58 of SS EN 1993-1-1:2005 to evaluate themodification factor ‘f’ for the LTB reduction factor χLT. To evaluate the modification factor SSEN 1993-1-1:2005 uses a correction factor ‘kc’ given by Table 6.6 in the code.

The Singaporean-NA however, specifies that the correction factor ‘kc’ is to be obtained asbelow:

Kc = 1 / √C1Where:

C1 is to be obtained from the NCCI documents as previously described (See"Clause 6.3.2.2 –Elastic critical moment and imperfection factors for LTB checks"on page 329). The NCCI document SN003a-EN-EU specifies the values of C1 to beused in table 3.1 as shown below. The current implementation does not accountfor the Kc factor and conservatively uses a reduction factor equal to 1. Theprogram allows for the reduction factor based on the Singaporean-NA.


These values are for an end restraint factor of k = 1 (i.e., design parameter CMN = 1.0). Hence forall other values of CMN (i.e., 0.7 or 0.5) this implementation will use the values of C1 from DDENV 1993-1-1:1992 Annex F.

The program will use a default value of 1.0 for Kc. However, you can also input a custom valueof Kc by setting the design parameter KC to the desired value. If the KC parameter in thedesign input is set to 0, then the program will automatically calculate its value. This willcause the 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. To evaluate C1,the program will use the NCCI documents as previously described.

7D.5.6 Clause 6.3.3(5) – Interaction factors kyy, kyz, kzy,and kzz

The Singaporean NA recommends the methods in either Annex A or Annex B of SS-EN 1993-1-1 to calculate these interaction factors. The current implementation of EC3 BS in STAAD.prouses the method in Annex B by default. The proposed implementation of the Singaporean NAwill also use Annex B for Cl.6.3.3 checks.

However for non-doubly symmetric sections, the Singaporean NA gives the option of usingAnnex B with some modifications as given in the NA. (Cl. NA-3.2 of the Singaporean NA).The Singaporean 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 SS EN 1993-1-1:2005.

As per the Singaporean NA, for non-doubly symmetric sections, the slenderness about theweak axis (λy in STAAD) and the corresponding reduction factor χy should be taken as thevalues from the highest values of slenderness (λ) among the flexural buckling slenderness(λy), torsional slenderness (λT) and torsional-flexural slenderness (λTF) as given in Clauses6.3.1.3 and 6.3.1.4 of SS EN 1993-1-1:2005. Hence for non-doubly symmetric sections theprogram will calculate the critical non-dimensional slenderness as:

λy = the maximum of either λ from Cl 6.3.1.3 or λT from Cl 6.3.1.4

Where:

=⋅

λTA f

N

y

cr

Ncr = min (NCrT, NcrTF).

The Singaporean NA or EC3 does not, however, specify a method to evaluate NCrT or NcrTF.Therefore, the program uses the method specified in the NCCI document “SN001a-EN-EU:Critical axial load for torsional and flexural torsional buckling modes” to calculate these. See"Clause 6.3.1.4 - Slenderness for torsional and torsional-flexural buckling" on page 336.

Note: The Singaporean National Annex or EC3 does not deal with angle sections inspecific and hence this implementation will use the method used in the currentEC3 implementation to deal with slenderness of angle sections. In the currentimplementation this is done as per cl 4.7.10 of BS 5950. This proposed

335— STAAD.Pro

implementation will still use the same method for single and double angle sectionsto evaluate the slenderness.

Clause NA 3.2 of the Singaporean 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 3 section for thepurposes of this clause”. Hence, for all Class 1 or Class 2 cross sections that are not I, H, SHS,RHS or CHS sections, the elastic properties will be used for the purposes of 6.3.3 checks.


Equations 6.52 and 6.53 of SS EN 1993-1-1:2005 are to be used to calculate the non-dimensionalslenderness parameter, λT, to be used for torsional and torsional-flexural buckling checks. TheSS EN 1993-1-1:2005 does not provide equations to calculate the elastic critical loads Ncr,T,F andNcr,T (refer 6.3.14 of SS EN 1993-1-1:2005). Therefore, the NCCI document “SN001a-EN-EU:Critical axial load for torsional and flexural torsional buckling modes” provides methods tocalculate the Ncr,T,F and Ncr,T factors and hence will to be included in this implementation ofthe Singaporean NA.


=

+

N GIcr Ti

t

π EI

I,

1

o

w

T

2

2

2

Where:

= + + +i i i y zo y z o o2 2 2 2 2



=

+ − + −

+


i


i i

i( ),2

, , , ,

2

, ,o

y z

y z

o

2

2 2

2 2

2


The program will only consider Channel Sections and Tee- sections while working out thecritical torsional and Flexural Torsional buckling loads as per Cl 6.3.1.4.

7D.6 Belgian National Annex to EC3Adds values from the Belgian National Annex—titled National Annex to Standard NBN-EN1993-1-1—for use with Eurocode 3, or EN 1993-1-1:2005. The NA document makes small changesto the base document.


Clause 6.3.2.4(1) B – Slenderness for flexural buckling


STAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Belgian National Annex.

Clause 6.3.2.4(2)B – Modification factor ‘kfl’STAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Belgian National Annex.

Note: Refer to the basic code (EC3) for a description of these clauses. The sections belowrefer to the corresponding clauses in the NBN-NA.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that have been dealtwith in the Belgian National Annex (hereafter referred to as NBN-NA) and that are relevantto the proposed implementation are:



The partial safety factors will use the following values for the Belgian National Annex:




The design function in STAAD.Pro sets these values as the default values for the PN-NA (NA8 is specified).




The NBN-NA recommends the use of Table 6.3 and 6.4 of EN 1993-1-1:2005 to calculate theimperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor χLT, requires the calculation of the Elastic CriticalBuckling Moment, Mcr. The NBN-NA gives a method to calculate Mcr in Annex D, which isused by STAAD.Pro. Annex D, however, only deals with the calculation of Mcr for doublysymmetric sections and mono symmetric sections that are symmetric about the minor axis(i.e, Tee sections). For any other type of section that is not dealt with by Annex D, STAAD.Prouses the method and tables given in Annex F of DD ENV 1993-1-1:1992:

337— STAAD.Pro

Doubly symmetric sections

Annex D of NBN-NA provides equation used to calculate Mcr specifically for doubly symmetricsections:

=

+ + −

M C C Z C Z( )cr

π EI

kL

k

k

I

I

kL GI

π EIg g1

( )

2( )

2

2

2w

w t2

2

2

2

C1 & C2 are factors that depend on the end conditions and the loading conditions. The Annexprovides values for C1 & C2 for the different cases as given in Table1 and Table 2 of the Annex.Table 1 deals with the condition of a simply supported member with end moments and thevalue of C1 is determined by the end moment ratio (Refer to the NA for details). Clause 3.2 ofthe National Annex however gives a formula to calculate C1 as:

C1 = 1.77 - 1.04ψ + 0.27ψ2 ≤ 2.60

The value of C2 is determined based on the Table 2 of the Annex, based on the loading andend conditions as specified using the CMM parameter.

This NBN-NA considers three separate loading conditions:




STAAD.Pro accounts for the loading condition and the bending moment diagram throughthe CMM parameter.

Mono-symmetric sections with symmetry about their weak axis

Annex D of NBN-NA also provides a method to evaluate the elastic critical moment, Mcr, foruniform mono symmetric sections that are symmetric about the weak axis. Hence for thisimplementation the elastic critical moment for Tee-Sections is evaluated using the method inthis Annex.



=

+ + − − −


π EI

k L

k

k

I

I

k L GI

π EIg g

( )

( )1

2

2 3 1

2

2 3 1z

x

x

w

w x T

z

2

2

2

2

The factors C1, C2, and C3 are dependent on the end conditions and loading criteria. Thisimplementation will consider C1, C2 and C3 as given in the tables below:


End Moments andSupport Conditions

Bend-ingmome-ntdia-gram

kz

Value ofcoefficients

C1

C3

ψf

≤ 0ψf

> 0

ψ = +1 1.-0

1.0-0

1.000

Table 7D.8-Critical moment coefficients for singlysymmetric sections with end moments

339— STAAD.Pro



kz


C1

C3

ψf

≤ 0ψf

> 0

0.-5

1.0-5

1.019




kz


C1

C3

ψf

≤ 0ψf

> 0

ψ =+3/4

1.-0

1.1-4

1.000

341 — STAAD.Pro



kz


C1

C3

ψf

≤ 0ψf

> 0

0.-5

1.1-9

1.017




kz


C1

C3

ψf

≤ 0ψf

> 0

ψ =+1/2

1.-0

1.31 1.000

343— STAAD.Pro



kz


C1

C3

ψf

≤ 0ψf

> 0

0.-5

1.3-7

1.000

ψ =+1/4

1.-0

1.5-2

1.000

0.-5

1.6-0

1.000

ψ = 0 1.-0

1.7-7

1.000

0.-5

1.8-6

1.000

ψ = -1/4

1.-0

2.0-6

1.00-0

0.85-0

0.-5

2.1-5

1.00-0

0.65-0

ψ = -1/2

1.-0

2.3-5

1.00-0

1.3 -1.2ψ

f

0.-5

2.4-2

0.95-0

0.77- ψf

ψ = -3/4

1.-0

2.6-0

1.00-0

0.55- ψf

0.-5

2.4-5

0.85-0

0.35- ψf

ψ = -1 1.-0

2.6-0

-ψf -ψf

0.-5

2.4-5

0.12-5 -0.7-ψf

-0.12-5 -0.7-ψf


Note: According to Section 3(1): C2zg = 0

Load andsupportconditions

Bending momentdiagram

k

z

Value ofcoef-ficients

C

1

C

2

C

3

1-.-0

1.-1-2

0-.-4-5

0.-52-5

0-.-5

0-.-9-7

0-.3-6

0.-47-8

1-.-0

1.-3-5

0-.5-9

0.-41-1

0-.-5

1.-0-5

0-.-4-8

0.-33-8

1-.-0

1.-0-4

0-.-4-2

0.-56-2

0-.-5

0-.-9-5

0-.3-1

0.-53-9

Table 7D.9-Value of coefficients

The CMM parameter specified during design input will determine the values of C1, C2, andC3. The default value of CMM is 0, which considers the member as a pin ended member withuniformly distributed load (UDL) along its span. This NCCI does not however consider the“end moments and transverse loading” condition. The user however can use the new ‘C1’, ‘C2’and ‘C3’ parameters to input the required values for C1, C2 and C3 to be used in calculatingMcr.

345— STAAD.Pro


Both the NCCI documents mentioned above assume that the member under consideration isfree to rotate on plan and that there are no warping restraints for the member ( k = kw = 1.0).STAAD.Pro takes into account of the end conditions using the CMN parameter for EC3. A valueof K = kw =1 is indicated by a value of CMN = 1.0 in the design input. Hence the abovemethods will be used only for members which are free to rotate on plan and which have nowarping restraints (i.e., CMN = 1.0). For members with partial or end fixities (i.e., CMN = 0.5 orCMN = 0.7), this implementation will fall back on to the method and coefficients in DD ENV1993-1-1:1992 – Annex F.



Note: The program does not consider the case of cantilevers.


The NBN-NA recommends the use of the values specified in EN 1993-1-1 for the LTB factorsλLT0 and β. However it gives two different sets of values for λLT0 & β based on two differentconditions as give below:

1. If Mcr is determined by considering the properties of the gross cross section and thelateral restraints, the following values are used:

λLT0 =0.2 and β = 1.0

2. If Mcr is determined by ignoring the lateral restraints, the following values are used:

λLT0 =0.4 and β = 0.75

The program evaluates which factors to use based on the CMN parameter. If CMN = 1.0(default), then the program assumes the restraints are ignored and the second set of values isused for λLT0 and β. If CMN = 0.5, then the first set of λLT0 and β values is used.

These factors are then applied to equation 6.57 of NBN-EN to evaluate the Lateral TorsionalBuckling reduction factor χLT.


7D.6.4 Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTBReduction factor, χLT as per Belgium NA

Clauses 6.3.2.2 and 6.3.2.3 (EN 1993-1-1:2005) both give equations to evaluate the LTB reductionfactor χLT to be used in eqn. 6.55 of NBN-EN 1993-1-1:2005.


Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending members of constant crosssection the value of χLT should be determined from...”. Hence in the implementation of EC3(and the Belgian Annex) in STAAD.Pro: by default the program will consider clause Cl. 6.3.2.3to evaluate χLT. 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 Belgian National Annex gives equations to evaluate the imperfection factorsto be used for various section types. (See "Clause 6.3.2.3(1) – LTB for rolled sections orequivalent welded section" on page 346 ). Hence for all cases dealt with by the equations inthe NBN-NA, this implementation will use Cl 6.3.2.3 to evaluate χLT.


In any case, the elastic critical moment,Mcr, (used to evaluate the non dimensionalslenderness) will be evaluated as given above. Since this implementation uses the NCCIsmentioned in the sections above, only end restraint conditions corresponding to the CMNparameter=1.0 (See "Clause 6.3.2.3(1) – LTB for rolled sections or equivalent welded section" onpage 346 ) will be considered. For all other cases of the CMN parameter values, thisimplementation will use the method specified in Annex F of DD ENV 1993-1-1:1992.

You can override the default behavior and specify the clause that is to be used for LTB checks.This can be specified using the MTH design parameter (See "Design Parameters" on page 261).

Note: If a National Annex has not been specified (i.e., NA parameter in the design input= 0), the program will use Cl. 6.3.2.3 only in the case of Rolled or welded I & HSections. For all other cases, the program will use Cl. 6.3.2.2 of NBN-EN 1993-1-1:2005. Also, I sections with plates will be treated as built-up sections only if thesection has been explicitly specified as a built-up section (i.e., SBLT parameter = 1.0in design input).


The Belgian NA specifies that the modification factor is to be obtained as per the defaultmethod given in EC-3. Hence the proposed implementation will use the existing

347— STAAD.Pro

functionality to work out the correction factor ‘kc’ to be used in the modification factor f.

The program uses a default value of 1.0 for ‘kc’. However the user can also input a custom valueof ‘kc’ by setting the design parameter ‘KC’ to the desired value. The user can also get theprogram to calculate the value of ‘kc’ automatically by setting the value of the ‘KC’ parameterin the design input to 0. This will cause the program to work out ‘kc’ from table 6.6 of NBNEN 1993-1-1:2005. This will correspond to the end conditions and the bending moment of themember (i.e the value of CMM parameter specified).

l For CMM = 7 the program will choose the value of ‘kc’ to be either 0.90 or 0.91 based onthe end moment ratio.

l For CMM = 8 the program will choose the value of ‘kc’ to be either 0.77 or 0.82 based onthe end moment ratio.

An additional check will also be performed as given below:

≤χLT

λ,mod

1

LT

2


The NBN-NA recommends the equations in Annex A of NBN-EN 1993-1-1 to calculate theseinteraction factors.

The NA also mentions that torsional flexural buckling needs to be taken into account in caseof mono symmetric sections. Torsional flexural buckling will need to be taken into accountbased on the method given in the NCCI document “SN001a-EN-EU: Critical axial load fortorsional and flexural torsional buckling modes”. See section below for details.

The NA also recommends a lower limit as given below for the term Cmi,0 in table A.2 of AnnexA:

≥ −C 1mi

N

N, 0

Ed

cr i,


Equations 6.52 and 6.53 of NBN-EN 1993-1-1:2005 are to be used to calculate the non-dimensional slenderness parameter, λT, to be used for torsional and torsional-flexuralbuckling checks. The NBN-EN 1993-1-1:2005 does not provide equations to calculate the elasticcritical loads Ncr,T,F and Ncr,T (refer 6.3.14 of SS EN 1993-1-1:2005). Therefore, the NCCIdocument “SN001a-EN-EU: Critical axial load for torsional and flexural torsional bucklingmodes” provides methods to calculate the Ncr,T,F and Ncr,T factors and hence will to beincluded in this implementation of the Belgian NA.


=

+

N GIcr Ti

t

π EI

I,

1

o

w

T

2

2

2


Where:

= + + +i i i y zo y z o o2 2 2 2 2



=

+ − + −

+


i


i i

i( ),2

, , , ,

2

, ,o

y z

y z

o

2

2 2

2 2

2


The program will only consider Channel Sections and Tee- sections while working out thecritical torsional and Flexural Torsional buckling loads as per Cl 6.3.1.4.

7D.7 Malaysian National Annex to EC3Adds values from the Malaysian National Annex—titled National Annex to Standard MS-EN1993-1-1—for use with Eurocode 3, or EN 1993-1-1:2005. The NA document makes smallchanges to the base document.


Clause 6.3.2.4(1) B – Slenderness for flexural bucklingSTAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Malaysian National Annex.

Clause 6.3.2.4(2)B – Modification factor ‘kfl’STAAD.Pro does not use this clause for design per EC-3. Therefore, this clause isignored for the Malaysian National Annex.

Note: Refer to the basic code (EC3) for a description of these clauses. The sections belowrefer to the corresponding clauses in the MS-NA.

The clauses/sections in EN 1993-1-1:2005 (hereafter referred to as EC-3) that have been dealtwith in the Malaysian National Annex (hereafter referred to as MS-NA) and that are relevantto the proposed implementation are:



The partial safety factors will use the following values for the Malaysian National Annex:



349— STAAD.Pro


The design function in STAAD.Pro sets these values as the default values for the MS-NA (NA 9is specified).




The MS-NA recommends the use of Table 6.3 and 6.4 of MS EN 1993-1-1:2005 to calculate theimperfection factors for Lateral Torsional Buckling (LTB) checks.

The calculation of the LTB reduction factor χLT, requires the calculation of the Elastic CriticalBuckling Moment, Mcr. The MS-NA does not specify a particular method to calculate Mcr.Hence the calculation of Mcr has been based on the following NCCI documents:

Doubly symmetric sections

SN003a-EN-EU NCCI: Elastic critical moment for lateral torsional buckling provides equationused to calculate Mcr specifically for doubly symmetric sections:

=

+ + −

M C C Z C Z( )cr

π EI

kL

k

k

I

I

kL GI

π EIg g1

( )

2( )

2

2

2w

w

S

t

S

2

2

2

2

C1 and C2 are factors that depend on the end conditions and the loading conditions of themember. The NCCI provides values for C1 and C2 for the different cases as given in Table 3.1and Table 3.2.

The NCCI considers three separate loading conditions:




STAAD.Pro accounts for the loading condition and the bending moment diagram throughthe CMM parameter. The values of C1 and C2 may also be directly specified using the C1 and C2parameters, respectively (required for CMM = 7 or CMM = 8).

Mono-symmetric sections with symmetry about their weak axis

Annex D of MS-NA also provides a method to evaluate the elastic critical moment, Mcr, foruniform mono symmetric sections that are symmetric about the weak axis. Hence for this


implementation the elastic critical moment for Tee-Sections is evaluated using the methodin this Annex.

Note: Though this method could also be applicable to mono-symmetric built-upsections, STAAD.Pro currently does not have a means to specify/identify a mono-symmetric built-up section. Hence this implementation will use this method onlyfor Tee-Sections.


=

+ + − − −


π EI

k L

k

k

I

I

k L GI

π EIg g

( )

( )1

2

2 3 1

2

2 3 1z

x

x

w

w x T

z

2

2

2

2

The factors C1, C2, and C3 are dependent on the end conditions and loading criteria. Theprogram considers C1, C2, and C3 as given in the tables 4.1 and 4.2 of the NCCI, based on theCMM parameter.

The default value of CMM = 0, which considers the member as a pin ended member withuniformly distributed load (UDL) along its span. This NCCI does not however consider the“end moments and transverse loading” condition. You use the C1, C2 and C3 parameters toinput the required values for C1, C2, and C3, respectively, to be used in calculating Mcr.


Note:When CMM = 7 or CMM = 8, the values for C1, C2 and C3 parameters must bemanually specified.

Both the NCCI documents mentioned above assume that the member under consideration isfree to rotate on plan and that there are no warping restraints for the member ( k = kw = 1.0).STAAD.Pro takes into account of the end conditions using the CMN parameter for EC3. Avalue of K = kw =1 is indicated by a value of CMN = 1.0 in the design input. Hence the abovemethods will be used only for members which are free to rotate on plan and which have nowarping restraints (i.e., CMN = 1.0). For members with partial or end fixities (i.e., CMN = 0.5or CMN = 0.7), this implementation will fall back on to the method and coefficients in DDENV 1993-1-1:1992 – Annex F.


The term zg in the equation to calculate Mcr refers to the distance between the point ofapplication of load on the cross section in relation to the shear center of the cross section.The value of zg is considered positive, if the load acts towards the shear center and is negativeif it acts away from the shear center. By default, the program will assume that the load actstowards the shear center at a distance equal to (Depth of section/2) from the shear center.

351 — STAAD.Pro

The use will be allowed to modify this value by using the ZG parameter. Specifying a value ofZG = 0 in the design 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: The program does not consider the case of cantilevers.


The MS-NA specifies different values for the λLT,0 and β factors to be used in equation 6.57 ofMS EN 1993-1-1 for rolled and equivalent welded sections. STAAD.Pro does not differentiatebetween rolled and welded sections and uses the default values in MS EN 1993-1-1 for λLT,0and β. The values specified in the MS-NA are:

1. For rolled sections and hot-rolled & cold formed hollow sections:

λLT,0 = 0.4 and β = 0.75

2. For welded sections:

λLT,0 = 0.2 and β = 1.00

STAAD.Pro uses the buckling curves based on Table 6.5 of MS EN 1993-1-1:2005, based ondifferent limits. 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-doubly symmetric sections.Hence for these cases the new implementation will still use the method specified in the basecode as per clause 6.3.2.2(2).

7D.7.4 Clauses 6.3.2.2 and 6.3.2.3 — Calculation of LTBReduction factor, χLT as per Malaysian NA

Clauses 6.3.2.2 and 6.3.2.3 (EN 1993-1-1:2005), both give equations to evaluate the LTB reductionfactor χLT to be used in eqn. 6.55 of MS EN 1993-1-1:2005.


Cl. 6.3.2.2 states “Unless otherwise specified, see 6.3.2.3, for bending members of constant crosssection the value of χLT should be determined from...”. Hence in the implementation of EC3(and the MS NA) in STAAD.Pro, by default the program will consider clause Cl. 6.3.2.3 toevaluate χLT. 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 MS NA states that Table 6.5 in MS EN 1993-1-1:2005 should be replaced withthe table given in the NA (See "Clause 6.3.2.3(1) – LTB for rolled sections or equivalent weldedsection" on page 352). Hence for all cases dealt with by the table in the MS NA, thisimplementation will choose the buckling curves from the MS NA. For any case that is not


dealt with by the table in the MS NA, the program will use the method given in Cl. 6.3.2.2 ofMS EN 1993-1-1:2005.

Hence for the following cross sections the program will use the Table in the MS NA forchoosing a buckling curve for LTB checks (when the MS NA has been specified):



l Angle Sections



For the following cross sections, the program will use Cl. 6.3.2.3 of MS EN 1993-1-1:2005 toevaluate χLT



In any case the Elastic critical moment “Mcr” (used to evaluate the non dimensionalslenderness) will be evaluated as described in "Clause 6.3.2.2 –Elastic critical moment andimperfection factors for LTB checks". Since the MS NA uses the NCCI documentsmentioned in the sections above, this implementation will only consider end restraintconditions corresponding to the CMN parameter=1.0. For all other cases of the CMN parametervalues, this implementation will use the method 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 the design input= 0), the program will use Cl. 6.3.2.3 only in the case of Rolled or welded I & HSections. For all other cases, the program will use Cl. 6.3.2.2 of MS EN 1993-1-1:2005.Also, I sections with plates will be treated as built-up sections only if the sectionhas been explicitly specified as a built-up section (i.e., SBLT parameter = 1.0 indesign input).


The MS NA specifies the use of eqn. 6.58 of MS EN 1993-1-1:2005 to evaluate the modificationfactor, f, for the LTB reduction factor χLT. To evaluate the modification factor MS EN 1993-1-1:2005 uses a correction factor, kc, given by Table 6.6 in the code.

The program does not calculate the kc factor and conservatively uses a reduction factor equalto 1. The proposed implementation will allow for the reduction factor based on the MS NA.

These values are for an end restraint factor of k = 1 (i.e., CMN = 1.0). Hence for all other valuesof CMN (i.e., 0.7 or 0.5), the program uses the values of C1 from DD ENV 1993-1-1:1992 Annex F.

353— STAAD.Pro

You can also manually specify a value for kc by setting the design parameter, KC, to the desiredvalue. The user 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 the program to evaluatea value of C1 corresponding to the end conditions and the Bending moment of the memberand in turn calculate kc as given in the NA. To evaluate C1, the program will use the NCCIdocuments (See "Clause 6.3.2.2 –Elastic critical moment and imperfection factors for LTBchecks" on page 350).

Note that for the MS NA, the program will attempt to evaluate kc by default using theequation in NA,

=kc C1 / 1

where C1 will be the value used for the Mcr calculations.

If kc evaluates to be greater than 1.0, the program will then evaluate kc as per Table 6.6 of EN1993-1-1:2005.


The MS NA recommends that the method in Annex A or Annex B of MS EN 1993-1-1:2005 canbe used to calculate the interaction factors for Cl. 6.3.3 checks in the case of doubly symmetricsections. STAAD.Pro uses the equations in Annex B of MS EN 1993-1-1:2005 to calculate theseinteraction factors for doubly symmetric sections..

However, for non-doubly symmetric sections, the MS NA gives the option of using Annex Bwith some modifications as given in the NA. (Cl. NA-3.2 of the MS NA). The MS NA requiresadditional checks to be done to check for the maximum allowable values of λ and X to be usedin equations 6.61 and 6.62 of MS EN 1993-1-1:2005.

As per the MS NA, for non-doubly symmetric sections, the slenderness about the weak axis (λyin STAAD.Pro) and the corresponding reduction factor χy should be taken as the values fromthe highest values of slenderness (λ) among the flexural buckling slenderness (λy), torsionalslenderness (λT) and torsional-flexural slenderness (λTF) as given in Clauses 6.3.1.3 and 6.3.1.4 ofMS EN 1993-1-1:2005. Hence for non-doubly symmetric sections the program will calculate thecritical non-dimensional slenderness as:

=

λλ

λmax

per Cl. 6.3.1.3

per Cl. 6.3.1.4y

T

where

=⋅

λTA f

N

y

cr

=N N Nmin( , )cr crT crTF

The MS NA or EC3 does not, however, specify a method to evaluate NcrT or NcrTF. Hence, theprogram uses the method specified in the NCCI document SN001a-EN-EU: Critical axial load


for torsional and flexural torsional buckling modes to calculate these. See "Clause 6.3.1.4 -Slenderness for torsional and torsional-flexural buckling" on page 355 for details.

Note: The MS NA or EC3 does not deal with angle sections specifically and thereforeSTAAD.Pro uses the method described in the EC3 implementation to deal withslenderness of angle sections. This is done as per cl 4.7.10 of BS 5950.

Clause NA 3.2 of the MS NA also requires that “Where the section is not an I Section or ahollow section and is a class1 or class 2 section, it will be treated as a class 3 section for thepurposes of this clause”. Hence for all Class 1 or Class 2 cross sections that are not I, H, SHS,RHS or CHS sections, the elastic properties will be used for the purposes of 6.3.3 checks.


Equations 6.52 and 6.53 of MS-EN 1993-1-1:2005 are to be used to calculate the non-dimensional slenderness parameter, λT, to be used for torsional and torsional-flexuralbuckling checks. The MS-EN 1993-1-1:2005 does not provide equations to calculate the elasticcritical loads Ncr,T,F and Ncr,T (refer 6.3.14 of SS EN 1993-1-1:2005). Therefore, the NCCIdocument SN001a-EN-EU: Critical axial load for torsional and flexural torsional bucklingmodes provides methods to calculate the Ncr,T,F and Ncr,T factors and hence will to beincluded in this implementation of the MS NA.


=

+

N GIcr Ti

t

π EI

I,

1

o

w

T

2

2

2

Where:

= + + +i i i y zo y z o o2 2 2 2 2



=

+ − + −

+


i


i i

i( ),2

, , , ,

2

, ,o

y z

y z

o

2

2 2

2 2

2


The program will only consider Channel Sections and Tee- sections when evaluating thecritical torsional and Flexural Torsional buckling loads as per Cl 6.3.1.4.

355— STAAD.Pro

7E. Timber Design Per EC 5: Part 1-1STAAD.Pro is capable of performing timber design based on the European code EC5 Part 1-1Eurocode 5: Design of timber structures - Part 1.1: General-Common rules and rules forbuildings.

Design of members per EC5 Part 1-1 requires the STAAD Euro Design Codes SELECT CodePack.

7E.1 General CommentsPrinciples of Limit States Design of Timber Structures are used as specified in the code.

Design per EC5 is limited to the prismatic, rectangular shapes only. There is no Eurocode-specific timber section database / library consisting of pre-defined shapes for analysis or fordesign. The feature of member selection is thus not applicable to this code.

The design philosophy of this specification is based on the concept of limit state design.Structures are designed and proportioned taking into consideration the limit states at whichthey would become unfit for their intended use. Two major categories of limit-state arerecognized - ultimate and serviceability. The primary considerations in ultimate limit statedesign are strength and stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all timber structuresunder various loading conditions and at the same time the chances of limits being surpassedare acceptably remote.

In the STAAD implementation, members are proportioned to resist the design loads withoutexceeding the limit states of strength, stability and serviceability. Accordingly, the mosteconomic section is selected on the basis of the least weight criteria as augmented by thedesigner in specification of allowable member depths, desired section type, or other suchparameters. The code checking portion of the program checks whether code requirements foreach selected section are met and identifies the governing criteria.

The following sections describe the salient features of the STAAD implementation of EC 5. Adetailed description of the design process along with its underlying concepts and assumptionsis available in the specification document.

7E.1.1 Axes convention in STAAD and EC5

STAAD defines the major axis of the cross-section as zz and the minor axis as yy. Thelongitudinal axis of the member is defined as x and joins the start joint of the member to theend with the same positive direction.

EC5, however, defines the principal cross-section axes in reverse to that of STAAD, but thelongitudinal axis is defined in the same way. Both of these axes definitions follow theorthogonal right hand rule.


Figure 7E.1 - Axis conventions per STAAD and Eurocode 5

STAAD EC5

7E.1.2 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 less than thereference width in tension the characteristic strength in tension (ft0k) is to beincreased by the factor Kh.

For members, subjected to bending, whose depth is less than reference depth inbending, the characteristic strength in bending (fmk) is to be increased by the factorKh.

As per clause 3.2(3) of EC 5- 2004, for rectangular solid timber with a characteristictimber density ρk ≤ 700 kg/m

3 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 the value ofKh for Glued laminated timber and Laminated veneer lumber respectively.

D. KC90 – Factor taking into account the load configuration, possibility of splitting anddegree of compressive deformation.

For members, subjected to compression, perpendicular to the direction of grainalignment, this factor should be taken into account. Default value of 1 is used inSTAAD.Pro. User may override the value. Please refer clause 6.1.5 of EC-5-2004 in thisregard.

E. Km – Factor considering re-distribution of bending stress in cross section.

357— STAAD.Pro

7E. Timber Design Per EC 5: Part 1-1

For members, subjected to bending, this factor is taken into account for stress checking.For rectangular section the value of Km is 0.7, and this value is incorporated inSTAAD.Pro. User may override the value. Please refer clause 6.1.6 of EC-5-2004 in thisregard.

F. Kshape – Factor depending on shape of cross section.

For members, subjected to torsional force, design torsional stress should be less thanequal design shear strength multiplied by the factor Kshape. This factor is determinedby STAAD.Pro internally using the guidelines of clause 6.1.8 of EC-5-2004.

7E.2 Analysis Methodology

Symbol Description

St0d Design tensile stress parallel (at zero degree) to grainalignment.

St90d Design tensile stress perpendicular (at 90 degrees) to grainalignment.

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 grainalignment.

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.

Table 7E.1-EC5 Nomenclature


Symbol Description

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.

Equations for Characteristic Values of Timber Species as per Annex-A of EN 338:2003

The following equations were used to determine the characteristic values:

For a particular Timber Strength Class (TSC), the following characteristic strength values arerequired to compute the other related characteristic values.

i. Bending Strength – fm,kii. Mean Modulus of Elasticity in bending – E0, meaniii. Density - ρk

SIN-o.

Property Symbol Wood Type

Soft-wood (C)

Hard-wood (D)

1. Tensile Strength parallel tograin

ft,0,k 0.6 * fm,k

2. Tensile Strength perpendicularto grain

ft,90,k Minimum of 0.6 and(0.0015*rk)

3. Compressive Strength parallelto 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*fm,k

0.8)6. Modulus of Elasticity parallel

to grainE0,05 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 differwith the tabulated values in Table-1 of EN 338:2003. However, in all such cases, the valuesobtained from the provided equations are treated as actual and is used by the program, as thevalues of Table-1 are based on these equations.

359— STAAD.Pro


7E.2.1 Design values of Characteristic Strength

As per clause 2.4.1, Design values of a strength property shall be calculated as:

Xd = K mod·(Xk/γm)

Where:

Xd is design value of strength property

Xk characteristic value of strength property

γm is 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 cross sectional properties,different load and material factors, timber strength class, load duration class, service class andso on. The methodology adopted in STAAD for calculating the member resistance is explainedhere.

7E.2.2 Check for Tension stresses

If the direction of applied axial tension is parallel to the direction of timber grain alignment,the following formula should be checked per Equation 6.1 of EC-5 2004:

St0d/Ft0d ≤ RATIO

If the direction of applied axial tension is perpendicular to the direction of timber grainalignment, the following formula should be checked:

St90d/Ft90d ≤ RATIO

7E.2.3 Check for Compression stresses

If the direction of applied axial compression is parallel to the direction of timber grainalignment, the following formula should be checked per Equation 6.2 of EC-5 2004:

Sc0d/Fc0d ≤ RATIO

If the direction of applied axial compression is perpendicular to the direction of timber grainalignment, the following formula should be checked per Equation 6.3 of EC-5 2004:

St0d/(Ft0d·Kc90) ≤ RATIO

7E.2.4 Check for Bending stresses

If members are under bending stresses, the following conditions should be satisfied perEquations 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


7E.2.5 Check for Shear stresses

Horizontal stresses are calculated and checked against allowable values per Equation 6.13 ofEC-5 2004:

Svd/Fvd ≤ RATIO

7E.2.6 Check for Torsional stresses

Members subjected to torsional stress should satisfy Equation 6.14 of EC-5 2004:

Stor_d/(Kshape·Ftor_d) ≤ RATIO

7E.2.7 Check for combined Bending and Axial tension

Members subjected to combined action of bending and axial tension stress should satisfyEquations 6.17 and 6.18 of EC-5 2004:


(St0d/Ft0d) + (Smzd/Fmzd) + Km·(Smyd/Fmyd) ≤ RATIO

(St0d/Ft0d) + Km·(Smzd/Fmzd) + (Smyd/Fmyd) ≤ RATIO

7E.2.8 Check for combined Bending and axial Compression

If members are subjected to bending and axial compression stress, Equations 6.19 and 6.20 ofEC-5 2004 should be satisfied:


(Sc0d/Fc0d)2 + (Smzd/Fmzd) + Km·(Smyd/Fmyd) ≤ RATIO

(Sc0d/Fc0d)2 + Km·(Smzd/Fmzd) + (Smyd/Fmyd) ≤ RATIO

7E.2.9 Stability check

A. Column Stability check

The relative slenderness ratios should be calculated per Equations 6.21 and 6.22 of EC-52004.


λrel,z = λz/π·(Sc0k/E0,05)1/2

λrel,y = λy/π·(Sc0k/E0,05)1/2

361 — STAAD.Pro


If both λrel,z and λrel,y are less than or equal to 0.3 the following conditions should besatisfied:

(Sc0d/Fc0d)2 + (Smzd/Fmzd) + Km·(Smyd/Fmyd) ≤ RATIO

(Sc0d/Fc0d)2 + Km·(Smzd/Fmzd) + (Smyd/Fmyd) ≤ RATIO

In other cases, the conditions in Equations 6.23 and 6.24 of EC-5 2004 should besatisfied.


Sc0d/(Kcz·Fc0d) + (Smzd/Fmzd) + Km·(Smyd/Fmyd) ≤ RATIO

Sc0d/(Kcy·Fc0d) + Km·(Smzd/Fmzd) + (Smyd/Fmyd) ≤ RATIO

Where (Equations 6.25 through 6.28 of EC-5 2004):

Kcz = 1/Kz + [(Kz)2 - (λrel,z)

2]1/2

Kcy = 1/Ky + [(Kzy)2 - (λrel,y)

2]1/2

Kz = 0.5·[1 + βc·(λrel,z - 0.3) + (λrel,z)2]

Ky = 0.5·[1 + βc·(λrel,y - 0.3) + (λrel,y)2]

The value of βc incorporated 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, the stresses shouldsatisfy Equation 6.33 of EC-5 2004:

Smzd/(Kcrit·Fmzd) ≤ RATIO

Where a combination of moment about the strong z-axis and compressive force exists,the stresses should satisfy Equation 6.35 of EC-5 2004 (ref. to Equations 6.32 and 6.34 ofthe same):

[Smzd/(Kcrit·Fmzd)]2 + Sc0d/(Kcz·Fc0d) ≤ 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/(lef·Wz)

For softwood, use Equation 6.31 of EC-5 2004:

Sm,crit = 0.78·b2·E0,05/(h·lef)


7E.3 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure.

Depending on the model being designed, the user may have to change some or all of theparameter default values. Some parameters are unit dependent and when altered, the newsetting must be compatible with the active “unit” specification.



CODE - Must be specified as TIMBEREC5


See section 5.51.1 of theTechnical Reference Manual.

ALPHA 0.0 Angle of inclination of loadto the grain alignment. (Ref.Cl.6.1.1, Cl.6.1.2, Cl.6.1.3,Cl.6.1.4)

0.0 = Load parallel to grain90.0 = Load Perpendicularto grain

DFF None “Deflection Length” / Max.Allowable Net Final LocalDeflection.

In this case, deflection checkwill be performed, if both theparameters SERV and DFF arepresent with specific values.For appropriate range ofvalues, please refer Cl.7.2(Table 7.2)

Table 7E.2-Timber Design EC 5: Part 1-1 Parameters

363— STAAD.Pro



DJ1 Start node number for aphysical member underconsideration for DeflectionCheck.

DJ2 End node number for aphysical member underconsideration for DeflectionCheck.

KC90 1.0 Factor taking into accountthe load configuration,possibility of splitting anddegree of compressivedeformation. (Ref. Cl.6.1.5-(2))

l Range: 1.0 ≤ KC90 ≤ 4.0

l Other than the defaultvalue, user may specifyany value within therange, depending onload-position, load-dispersion, contactlength at supportlocations etc.

KLEF 1.0

(Member Length)

Effective Length Factor tocheck Lateral TorsionalBuckling (Ref. Table 6.1).Factor multiplied by the spanof the beam and depends onthe support conditions andload configurations. The userwill put the appropriate valuefrom the Table 6.1.

Required only for MTYP valueof 1 (Beam).

KY 1.0

(Member Length)

Effective Length Factor forLocal-y-axis. (Ref. Cl.6.3.2), forthe computation of therelative slenderness ratios.



KZ 1.0

(Member Length)

Effective Length Factor forLocal-z-axis. (Ref. Cl.6.3.2), forthe computation of therelative slenderness ratios.

LDC 1 Load Duration Class (Ref.Cl.2.3.1.2), required to get theK-MOD value from Table –3.1.

1.0 = Permanent action2.0 = Long term action3.0 = Medium term action4.0 = Short term action5.0 = Instantaneous action

MTYP 0 Member Type: Beam/Column.(Ref. Cl.6.3.2, Cl.6.3.3)

0.0 = Not defined; bothclauses are checked(Default)1.0 = Beam Member2.0 = Column Member

This information is requiredto find which stability checkwill be performed as per theCl 6.3 according to theMember Type.

RATIO 1.0 Permissible ratio of actual toallowable value.

SCL 3 Service Class (Ref. Cl.2.3.1.3)

1.0 = Class 1, Moisturecontent ≤ 12%2.0 = Class 2, Moisturecontent ≤ 20%3.0 = Class 3, Moisturecontent > 20%

365— STAAD.Pro



TRACK 0 Degree/Level of Details ofdesign output results.

1.0 = Print the designoutput at the minimaldetail level2.0 = Print the designoutput at theintermediate detail level3.0 = Print the designoutput that the maximumdetail level

TSC 6 (C24) Timber Strength Class (Ref.Reference EN338 – 2003)

l 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.

l Hardwood: 13 = D30, 14= D35, 15 = D40, 16 =D50, 17 = D60, 18 =D70.

This TSC definition willcalculate the correspondingcharacteristic strength valuesusing the equations as givenin BS-EN-338, Annex - A.

7E.4 Verification Problems

7E.4.1 Verification Problem No. 1 - Timber Column

A Timber Column of length 1.0 meter, having c/s dimension of 73 mm X 198 mm, is subjectedto an axial compressive force of 50.0 kN. Design the member for the ultimate limit state.

Material properties:

Timber class: C24

Service classes: Class 2, moisture content ≤ 20%


Load duration classes: 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 = 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 = 4.770x105 mm³

Section modulus of cross section about y-axis: Wy = 1.759x105 mm³

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·fc0k)/γm = (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 = (1000xFx)/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

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·(fc0k/E0,05)1/2 = 17.54/π(21.00/0.739)1/2 = 0.298

367— STAAD.Pro


λrel,y = λy/π·(fc0k/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:



Where:

Kz = 0.5·[1 + βc·(λrel,z - 0.3) + (λrel,z)2] = 0.50·[1 + 0.2(0.298 - 0.3) + (0.298)2] = 0.541

Ky = 0.5·[1 + βc·(λrel,y - 0.3) + (λrel,y)2] = 0.50·[1 + 0.2(0.809 - 0.3) + (0.809)2] = 0.878


2]1/2 = 1/0.541 + [(0.541)2 - (0.298)2]1/2= 1.008


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 to Compression only, soactual bending stress is zero.

Sc0d/(Kcz·Fc0d) + (Smzd/Fmzd) + Km·(Smyd/Fmyd) = 3.46/(1.008·12.92) + 0.0 + 0.0 = 0.268+ 0.0 + 0.0 = 0.266

Sc0d/(Kcy·Fc0d) + Km·(Smzd/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.

Comparison


Critical Ratio(Cl. 6.3.2)

0.326 0.327 none

Table 7E.3-EC 5: Part 1-1 Verification Problem 1

Input File

The following file is included AS C:\SProV8i\STAAD\Examp\Eur\EC5 ver 1.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;


ISOTROPIC WOOD

E 1.10316E+007


POISSON 0.15

DENSITY 0.00231749

ALPHA 5.5E-006

END DEFINE MATERIAL

CONSTANTS

MATERIAL WOOD MEMB 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 FX -50

PERFORM ANALYSIS

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 )***********************



FX MY MZLOCATION

==================================================================-=====

1 PRIS ZD = 0.073 YD = 0.198

PASS CL.6.3.2 0.3271

50.00 C 0.00 0.000.0000

369— STAAD.Pro


|--------------------------------------------------------------------------|| 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 = 0.000 fbz = 0.000

|| fc = 3.459

||----------------------------------------------------------------

----------|

7E.4.2 Verification Problem No. 2

A Timber Column of length 1.0 meter, having c/s dimension of 73 mm X 198 mm, is subjectedto an axial compressive force of 5.0 kN and moments of 2.0 kN.m and 1.0 kN.m about its majorand minor axes respectively. Design the member for the ultimate limit state.


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 = 4.770x105 mm³

Section modulus of cross section about y-axis: Wy = 1.759x105 mm³

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·fc0k)/γm = (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·(fc0k/E0,05)1/2 = 17.54/π(21.00/7370)1/2 = 0.298

λrel,y = λy/π·(fc0k/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 [Cl 6.3.2.3]:



Where:

Kz = 0.5·[1 + βc·(λrel,z - 0.3) + (λrel,z)2] = 0.50·[1 + 0.2(0.298 - 0.3) + (0.298)2] = 0.541

Ky = 0.5·[1 + βc·(λrel,y - 0.3) + (λrel,y)2] = 0.50·[1 + 0.2(0.809 - 0.3) + (0.809)2] = 0.878


2]1/2 = 1/0.541 + [(0.541)2 - (0.298)2]1/2= 1.008


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·Fx/A) = (1000·5.000)/14454 = 0.35 N/mm²

Smzd = (106·Mz)/Wz = (106·2.000)/(4.770x105) = 4.19 N/mm²

Smyd = (106·My)/Wy = (106·1.000)/(1.759x105) = 5.69 N/mm²

371 — STAAD.Pro


Combined stress ratio:

Sc0d/(Kcz·Fc0d) + (Smzd/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·Fc0d) + Km·(Smzd/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


Critical Ratio(Cl. 6.3.2)

0.616 0.616 none

Table 7E.4-EC 5: Part 1-1 Verification Problem 2

Input File

The following file is included AS C:\SProV8i\STAAD\Examp\Eur\EC5 ver 2.std.

STAAD SPACE

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 1 0;

MEMBER INCIDENCES

1 1 2;


ISOTROPIC WOOD

E 1.10316E+007

POISSON 0.15

DENSITY 0.00231749

ALPHA 5.5E-006

END DEFINE MATERIAL

CONSTANTS

MATERIAL WOOD MEMB 1

MEMBER PROPERTY

1 PRIS YD 0.198 ZD 0.073

SUPPORTS

1 FIXED


JOINT LOAD


2 FY -5.0 MX 1.0 MZ 2.0

PERFORM ANALYSIS

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 )***********************



FX MY MZLOCATION

==================================================================-=====

1 PRIS ZD = 0.073 YD = 0.198

PASS CL.6.3.2 0.6161

5.00 C 1.00 -2.000.0000|---------------------------------------------------------------

-----------|| 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)

|

373— STAAD.Pro


| fby = 5.686 fbz = 4.193|

| fc = 0.346|

|--------------------------------------------------------------------------|


375— STAAD.Pro

Section 8

Finnish Codes


377— STAAD.Pro

8A. Finnish Codes - Concrete Design per B4STAAD.Pro is capable of performing concrete design based on the Finnish code B4 Suomenrakentamismääräyskokoelma, B4 Betonirakenteet (National Building Code of Finland, B4Concrete structures).

Design of members per B4 requires the STAAD N. Eurozone Design Codes SELECT Code Pack.


379— STAAD.Pro

8A.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to the B4 code. 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 valuesof commonly used parameters for conventional design practice have been chosen as the basis.The following table contains a complete list of available parameters with their default values.


ParameterName

DefaultValue

Description

CODE - Must be specified as FINNISH.

Design Code to follow. See section 5.52.2 ofthe Technical Reference Manual.

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 braced inonly the local Z direction.




DRYCIR 100 Drying exposure, in percent.



Table 8A.1-Finnish Concrete Design per B4 Parameters


ParameterName

DefaultValue

Description



ENVIR 2 Environment class

1. LA — Least aggressive

2. NA — Aggressive

3. MA — Very aggressive

FC 35 N/mm2 Compressive strength of concrete.

FYMAIN 500 N/mm2 Yield strength of main reinforcing steel.

LAGE 7 days Age when loaded, in days.

MAXMAIN

32 Maximum size permitted for mainreinforcement bar.

MINMAIN 10 Minimum size permitted for mainreinforcement 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 about minoraxis.

3. Two faced distribution about majoraxis.

4. Faced symmetric distribution

381 — STAAD.Pro

ParameterName

DefaultValue

Description

SFACE 0 Distance from the start node of the beam toface of support for shear design.


STIRANG 90 Stirrup angle, in degrees.

STIRDIA 10 mm Stirrup diameter

TORANG 45 Torsion angle, in degrees.

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 tensionstiffening.

12. Beam — Ultimate limit state designonly

20. Slab — Plane stress design.

30. Slab — Simplified membrane design.

8A. Finnish Codes - Steel Design per B7STAAD.Pro is capable of performing steel design based on the Finnish code B7 Suomenrakentamismääräyskokoelma, B4 Betonirakenteet, Liite 3: Kansallinen liite standardiin SFS-EN206-1 (The National Building Code of Finland - B Strength of Structures, B7 Steel StructuresGuidelines).

Design of members per B7 requires the STAAD N. Eurozone Design Codes SELECT Code Pack.

8A.2 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure.


ParameterName

DefaultValue

Description

CODE none Must be specified as B7.



BEAM 0.0 Parameter BEAM 1.0 ALL tells the program tocalculate von Mises at 13 sections along eachmember, and up to 8 points at each section.(Depending on what kind of shape is used.)

Note: Must be set to 1.0

BY 1.0 Buckling length coefficient, β for weak axisbuckling (y-y) (NOTE: BY > 0.0)

BZ 1.0 Buckling length coefficient, β, for strong axisbuckling (z-z) (NOTE: BZ > 0.0)

CB 1.0 Lateral buckling coefficient, Y. Used to calculatethe ideal buckling moments, Mvi

CMZ 1.5 n for built up section in connection with lateralbuckling

CY

CZ

Defaultsee NS3472

Buckling curve coefficient, a about local z-axis(strong axis). Represent the a, a0, b, c, d curve.

DMAX 100.0[cm]

Maximum allowable depth of steel section.

DMIN 0.0[cm]

Minimum allowable depth of steel section.

FYLD 235 Yield strength of steel, fy [N/mm2 ]

MF 1.0 Ratio of material factor / resistance factor

RATIO 1.0 Permissible ratio of the actual to allowablestresses.

SSY 0.0 0.0 = No sidesway. β calculated. > 0.0 = Sideswayin local y-axis weak axis βM=SSY

Table 8A.2-Design Parameters for Finnish B7 Steel design code

383— STAAD.Pro

8A. Finnish Codes - Steel Design per B7

ParameterName

DefaultValue

Description

SSZ 0.0 0.0 = No sidesway. β calculated. > 0.0 = Sideswayin local y-axis weak axis βM

TRACK 0.0 Specifies the level of detail in the output.

0.0 = Suppress critical memberstresses

1.0 = Print all critical memberstresses, i.e., design values

2.0 = Print von Mises stresses

3.0 = Member results, printed bymember number

9.0 = Print detailed report eachmember.

UNL Memberlength

Effective length for lateral buckling calculations(specify buckling length). Distance between forksupports or between effective side supports forthe beam

The parameter CMY will, when given with negative value, define an inside pressure in pipemembers. The pressure corresponds to given water depth in meters.

The parameter CB defines the φ value with respect to calculation of the ideal lateral bucklingmoment for single symmetric wide flange profiles, ref. NS app. 5.2.2.


385— STAAD.Pro

Section 9

French Codes


387— STAAD.Pro

9A. French Codes - Concrete Design per B.A.E.LSTAAD.Pro is capable of performing concrete design based on the French code BAEL 1991 EBéton Armé aux États Limites: Regles techniques de conception et de calcul des ouvrages etconstructions en beton arme, suivant la methode des etats limites (Reinforced Concrete LimitStates: Technical rules for design and costing and reinforced concrete, according to themethod of limit states). Given the width and depth (or diameter for circular columns) of asection, STAAD will calculate the required reinforcing to resist the various input loads.

Design of members per BAEL 1991 E requires the STAAD Eurozone Design CodesSELECT Code Pack.

9A.1 Design ParametersThe program contains a number of parameters which are needed to perform design perB.A.E.L. These parameters not only act as a method to input required data for codecalculations but give the engineer control over the actual design process. Default values, ofcommonly used numbers in conventional design practice, have been used for simplicity. Table7A.1 contains a complete list of available parameters and their default values.


ParameterName

DefaultValue

Description

CODE BAEL Must be specified as BAEL.



CLEAR * 20mm

Clearance of reinforcing bar. Value isautomatically set to 20 mm for C35 and higher.

DEPTH YD Depth of concrete member. This value defaults toYD as provided under MEMBER PROPERTIES.

EFACE *0.0 Face of Support Location at end of beam.

Note: Both SFACE and EFACE are input aspositive numbers.

FC * 30 N/mm2

Concrete Yield Stress.

Table 9A.1-French Concrete Design B.A.E.L. Parameters


ParameterName

DefaultValue

Description

FYMAIN * 300N/mm2

Yield Stress for main reinforcing steel.

FYSEC * 300N/mm2

Yield Stress for secondary reinforcing steel.

MAXMAIN

50 mm Maximum main reinforcement bar size. (8mm -60mm).

MINMAIN 8 mm Minimum main reinforcement bar size. (8mm -60mm).

MINSEC 8 mm Minimum secondary reinforcement bar size.(8mm - 60mm).

MMAG 1.0 A factor by which the design moments will bemagnified.

SFACE *0.0 Face of support location at start of beam. Onlyconsiders shear - use MEMBER OFFSET forbending.

NSECTION

10 Number of equally-spaced sections to beconsidered in finding critical moments for beamdesign.

TRACK 0.0 Critical Moment will not be printed out withbeam design report. A value of 1.0 will mean aprint out.


* These values must be provided in the units currently being used for input.

9A.2 Slenderness Effects and Analysis ConsiderationSTAAD provides the user two methods of accounting for the slenderness effect in the analysisand design of concrete members. The first method is a procedure which takes into accountsecond order effects. Here, STAAD accounts for the secondary moments, due to axial loadsand deflections, when the PDELTA ANALYSIS command is used. STAAD, after solving forthe joint displacements of the structure, calculates the additional moments induced in thestructure. 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 slenderness effect isthrough user supplied moment magnification factors. Here the user approximates the

389— STAAD.Pro

9A. French Codes - Concrete Design per B.A.E.L

additional moment by supplying a factor by which moments will be multiplied beforebeginning member design.


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 and 300 mmwidth) and the second set of members, with only depth and no width provided, will beassumed to be circular with a 300 mm diameter. Note that area (AX) is not provided for thesemembers. If shear areas (AY & AZ) are to be considered in analysis, the user may provide themalong with YD and ZD. Also note that moments of inertia may be provided, but if notprovided, the program will calculate values from YD and ZD.

9A.4 Beam DesignBeam design includes both flexure and shear. For both types of beam action, all active beamloadings are scanned to create moment and shear envelopes, and locate critical sections. Thetotal number of sections considered is twelve, unless that number is redefined with theNSECTION parameter. From the critical moment values, the required positive and negative barpattern is developed, with cut-off lengths calculated to include required development length.

Shear design includes critical shear values plus torsional moments. From these values, stirrupsizes are calculated with proper spacing. The 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


CODE BAEL

FYMAIN 415 ALL

FYSEC 415 ALL

FC 35 ALL

CLEAR 25 MEM 2 TO 6


SFACE 100 MEMB 7 TO 9

EFACE 100 MEMB 7 TO 9




DESIGN BEAM 2 TO 9

END CONCRETE DESIGN

9A.5 Column DesignColumns are designed for axial force and biaxial moments at the ends. All active loadings aretested to calculate reinforcement. The loading which produces maximum reinforcement iscalled the critical load. Column design is done for square, rectangular, and circular sections.For rectangular and square sections, the reinforcement is always assumed to be equallydistributed on each side. That means the total number of bars will always be a multiple offour (4). This may cause slightly conservative results in some cases.

Example of Input Data for Column Design:

UNIT NEWTON MMS


CODE BAEL

FYMAIN 415 ALL

FC 35 ALL


MMAG 1.5 MEMB 4 5



END CONCRETE DESIGN

9A.6 Slab/Wall DesignSlab and walls are designed per BAEL 1983 specifications. To design a slab or wall, it must bemodeled using finite elements. The command specifications are in accordance with ChapterII, section 6.40.

Elements are designed for the moments Mx and My. These moments are obtained from theelement force output (see Section 3.8 of the Technical Reference Manual). The reinforcementrequired to resist Mx moment is denoted as longitudinal reinforcement and thereinforcement required to resist My moment is denoted as transverse reinforcement. Theparameters FYMAIN, FC, and CLEAR listed in Table 7A.1 are relevant to slab design. Otherparameters mentioned in Table 7A.1 are not applicable to slab design.

391 — STAAD.Pro

9A. French Codes - Concrete Design per B.A.E.L


Example of Input Data for Slab/Wall Design:

UNIT NEWTON MMS


CODE BAEL

FYMAIN 415 ALL

FC 25 ALL

CLEAR 40 ALL


END CONCRETE DESIGN


393— STAAD.Pro

9B. French Codes - Steel Design per the French CodeSTAAD.Pro is capable of performing steel design based on the French code CM66, 1977 editionCentre Technique Industriel de la Construction Metallique (Industrial Technical Center ofMetal Construction) publication entitled Design Rules for Structural Steelwork .

Design of members per CM66 requires the STAAD NEurozone Design Codes SELECT CodePack.

9B.1 General CommentsThe design philosophy embodied in this specification is based on the concept of limit statedesign. Structures are designed and proportioned according to the limit states of which theywould become unfit for their intended use. Two major categories of limit-states arerecognized: ultimate and serviceability. The primary considerations in ultimate limit statedesign are strength and stability; that in serviceability is deflection. Appropriate load andresistance factors are used so that uniform reliability is achieved for all steel structures undervarious loading conditions and at the same time the chances of limits being surpassed areacceptably remote.

In the STAAD implementation, members are proportioned to resist the design loads withoutexceeding the limit states of strength, stability and serviceability. Accordingly, the mosteconomic section is selected on the basis of the least weight criteria, as augmented by thedesigner in specification of allowable member depths, desired section type, or other relatedparameters. The code checking portion of the program verifies that code requirements for eachselected section are met and also identifies the governing criteria.

The next few sections describe the salient features of STAAD implementation of "Design Rulesfor Structural Steelwork." A detailed description of the design process, along with itsunderlying concepts and assumptions, is available in the specification document.

9B.2 Basis of MethodologyThe "Design Rules for Structural Steelwork (Revision 80)" permits the usage of elastic analysis.Thus, in STAAD, linear elastic analysis method is used to obtain the forces and moments inthe members. However, strength and stability considerations are based on the principles ofplastic behavior. Axial compression buckling and lateral torsional buckling are taken intoconsideration for calculation of axial compression resistance and flexural resistance ofmembers. Slenderness calculations are made and overall geometric stability is checked for allmembers.

9B.3 Member CapacitiesThe member strengths are calculated in STAAD according to the procedures outlined insection 4 of this specification. Note that the program automatically considers co-existence ofaxial force, shear and bending in calculating section capacities.

For axial tension capacity, procedures of section 4.2 are followed. For axial compressioncapacity, formulas of section 5.3 are used.


Moment capacities about both axes are calculated using the procedures of sections 4.5 and4.6. Lateral torsional buckling is considered in calculating ultimate twisting moment persection 5.22 of the specification. The parameter UNL (see Table 7B.1) must be used to specifythe unsupported length of the compression flange for a laterally unsupported member. Notethat this length is also referred to as twisting length.

9B.4 Combined Axial Force and BendingThe procedures of sections 4.55 and 5.32 are implemented for interaction of axial forces andbending. Appropriate interaction equations are used and the governing criterion isdetermined.

9B.5 Design ParametersThe design parameters outlined in Table 7B.1 may be used to control the design procedure.These parameters communicate design decisions from the engineer to the program, thusallowing the engineer to control the design process to suit an application's specific needs.

The default parameter values have been selected as frequently used numbers for conventionaldesign. Depending on the particular design requirements, some or all of these parametervalues may be changed to exactly model the physical structure.


ParameterName


CODE FRENCH Design Code to follow.


BEAM 0.0 0.0 = design only for end momentsand those at locations specified bySECTION command.

1.0 = calculate moments at tenthpoints long the beam, and usemaximum Mz for design.

C1 1.0 Parameter used in clause 5.21 in thecalculation of M(D), the criticaltwisting moment and as shown inCM 66 Addendum 80, table 5, usualrange from 0.71 to 4.10

Table 9B.1-French Steel Design Parameters

395— STAAD.Pro

9B. French Codes - Steel Design per the French Code

ParameterName


C2 1.0 Parameter used in clause 5.21 in thecalculation of M(D), the criticaltwisting moment and as shown inCM 66 Addendum 80, table 5, usualrange from 0.0 to 1.56

DFF None(Mandatoryfordeflectioncheck)

"Deflection Length" divided by theMaximum allowable local deflection


Joint No. denoting starting point forcalculation of "Deflection Length"(See Note 1)


Joint No. denoting end point forcalculation of "Deflection Length"(See Note 1)

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 slenderness ratioabout Y-axis for axial compression.

LZ MemberLength

Length to calculate slenderness ratioabout Z-axis for axial compression.

NSF 1.0 Net section factor for tensionmembers.

RATIO 1.0 Permissible ratio of actual load effectand design strength.


ParameterName


SAME* 0.0 Controls the sections to try during aSELECT process.

0.0 = Try every sectionof the same type asoriginal

1.0 = Try only thosesections with a similarname as original, e.g., ifthe original is an HEA100, then only HEAsections will be selected,even if there are HEM’sin the same table.

TRACK 0.0 0.0 = Suppress printing of all designstrengths.

1.0 = Print all design strengths.

UNF 1.0 Same as above provided as a fractionof member length.

UNL MemberLength

Unsupported length of compressionflange for calculating momentresistance.

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

9B.6 Code Checking and Member SelectionBoth code checking and member selection options are available in the STAAD.Proimplementation of CM 66 (Revn. 80).



9B.7 Tabulated Results of Steel DesignResults of code checking and member selection are presented in the output file in a tabularformat.

397— STAAD.Pro


Note: COND CRITIQUE refers to the section of the CM 66 (Revn. 80) specification whichgoverned the design.

If the TRACK parameter is set to 1.0, calculated member capacities will be printed. Thefollowing 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 as individualcomponents of an analyzed structure. The member design facilities provide the user with theability to carry out a number of different design operations. These facilities may be usedselectively in accordance with the requirements of the design problem. The operations toperform 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.


These operations may be repeated by the user any number of times depending upon the designrequirements.

Currently STAAD supports steel design of wide flange, S, M, HP shapes, angle, double angle,channel, double channel, beams with cover plate, composite beams and code checking ofprismatic properties.

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


9B.8 Built-in French Steel Section LibraryThe following information is provided for use when the built-in steel tables are to bereferenced for member property specification. These properties are stored in a database file. Ifcalled for, the properties are also used for member design. Since the shear areas are built intothese tables, shear deformation is always considered for these members.

An example of the member property specification in an input file is provided at the end ofthis section.

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


9B.8.1 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

9B.8.2 HE shapes

HE shapes are specified as follows.

3 5 TA ST HEA120A

7 10 TA ST HEM140

13 14 TA ST HEB100

9B.8.3 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

9B.8.4 T Shapes

Tee sections are not input by their actual designations, but instead by referring to the I beamshapes from which they are cut. For example,

1 5 TA T IPE140

2 8 TA T HEM120

9B.8.5 U Channels

Shown below is the syntax for assigning 4 different names of channel sections.

399— STAAD.Pro


1 TO 5 TA ST UAP100

6 TO 10 TA ST UPN220

11 TO 15 TA ST UPN240A

16 TO 20 TA ST UAP250A

9B.8.6 Double U Channels

Back to back double channels, with or without a spacing between them, are available. Theletter 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 channel UAP150 with nospacing in between. Member 17 is a double channel UAP250A with a spacing of 0.5 lengthunits between the channels.

9B.8.7 Angles

Two types of specification may be used to describe an angle. The standard angle section isspecified as follows:

16 20 TA ST L30X30X2.7

The above section signifies an angle with legs of length 30mm and a leg thickness of 2.7mm.This specification may be used when the local Z axis corresponds to the z-z axis specified inChapter 2. If the local Y axis corresponds to the z-z axis, type specification "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 4 appears in thesection name, the decimal part is not part of the section name.


Short leg back-to-back or long leg back-to-back double angles can be specified by means ofinput of the words SD or LD, respectively, in front of the angle size. In case 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

43 TO 47 TA LD L80X80X6.5 SP 0.75



Section names of tubes, just like angles, consist of the depth, width and wall thickness asshown 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 wall thickness of2.7mm. Members 66 and 73 are tubes with a depth of 200mm, width of 100mm and a wallthickness of 8.0mm. Unlike angles, the ".0" in the thickness is part of the section name.

Tubes can also be input by their dimensions instead of by their table designations. Forexample,


is a tube that has a depth of 8 length units, width of 6 length units, and a wall thickness of0.5 length units. Only code checking, no member selection, will be performed for TUBEsections specified in this way.


To designate circular hollow sections, use PIP followed by numerical value of the diameterand thickness of the section in mm omitting the decimal portion of the value provided forthe 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, 64and 78 are pipes 219.1mm in dia, having a wall thickness of 12.5mm.



specifies a pipe with outside dia. of 25 length units and inside dia. of 20 length units. Onlycode checking, no member selection will be performed if this type of specification is used.

9B.8.11 Example

SAMPLE FILE CONTAINING FRENCH SHAPES

STAAD SPACE

UNIT METER KN

JOINT COORD

401 — STAAD.Pro


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

* DOUBLE ANGLES - SHORT LEGS BACK

* TO BACK

9 TA SD L30X20X4 SP 0.25

* DOUBLE ANGLES - LONG LEGS BACK

* TO BACK

10 TA LD L80X40X6 SP 0.75

* TUBES (RECTANGULAR OR SQUARE

* HOLLOW SECTIONS)

11 TA ST TUB50252.7

* TUBES (RECTANGULAR OR SQUARE

* HOLLOW SECTIONS)



13 TA ST PIP422.6



PRINT MEMB PROP

FINI


403— STAAD.Pro

Section 10

German Codes


405— STAAD.Pro

10A. German Codes - Concrete Design Per DIN 1045STAAD.Pro is capable of performing concrete design based on the German code DIN 1045-1:2001-07 Plain, reinforced and prestressed concrete structures. Part 1: Design and construction.Design for a member involves calculation of the amount of reinforcement required for themember. Calculations are based on the user specified properties and the member forcesobtained from the analysis. In addition, the details regarding placement of the reinforcementon the cross section are also reported in the output. Slab design is also available and thisfollows the requirements of Baumann, Munich, which is the basis for Eurocode 2.

Design of members per DIN 1045 requires the STAAD Eurozone Design Codes SELECT CodePack.


l For Beams — Prismatic (Rectangular & Square)

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


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 and 250 mmwidth) and the second set of members, with only depth and no width provided, will beassumed to be circular with 350 mm diameter. It is absolutely imperative that the user notprovide the cross section area (AX) as an input.

10A.3 Slenderness Effects and Analysis ConsiderationsSlenderness effects are extremely important in designing compression members. There are twooptions by which the slenderness effect can be accommodated.

The first method is equivalent to the procedure presented in DIN 1045 17.4.3/17.4.4 which isused as the basis for commonly used design charts considering e/d and sk/d for conditionswhere the slenderness moment exceeds 70. This method has been adopted in the columndesign in STAAD per the DIN code.

The second option is to compute the secondary moments through an analysis. Secondarymoments are caused by the interaction of the axial loads and the relative end displacements ofa member. The axial loads and joint displacements are first determined from an elasticstiffness analysis and the secondary moments are then evaluated. To perform this type of


analysis, use the command PDELTA ANALYSIS instead of PERFORM ANALYSIS in the input file.The user must note that to take advantage of this analysis, all the combinations of loadingmust be provided as primary load cases and not as load combinations. This is due to the factthat load combinations are just algebraic combinations of forces and moments, whereas aprimary load case is revised during the P-delta analysis based on the deflections. Also, notethat the proper factored loads (like 1.5 for dead load etc.) should be provided by the user.STAAD does not factor the loads automatically. The column is designed for the totalmoment which is the sum of the primary and secondary forces. The secondary moments canbe compared to those calculated using the charts of DIN 1045.

10A.4 Beam DesignBeams are designed for flexure, shear and torsion. For all these forces, all active beam loadingsare prescanned to identify the critical load cases at different sections of the beams. The totalnumber of sections considered is 13 (e.g., 0., .1, .2, .25, .3, .4, .5, .6, .7, .75, .8, .9 and 1). All ofthese sections are scanned to determine the design force envelopes.


Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging(creating tensile stress at the top face) moments are calculated for all active load cases at eachof the above mentioned sections. Each of these sections is designed to resist these criticalsagging and hogging moments. Currently, design of singly reinforced sections only ispermitted. If the section dimensions are inadequate as a singly reinforced section, such amessage will be printed in the output. Flexural design of beams is performed in two passes. Inthe first pass, effective depths of the sections are determined with the assumption of singlelayer of assumed reinforcement and reinforcement requirements are calculated. After thepreliminary design, reinforcing bars are chosen from the internal database in single ormultiple layers. The entire flexural design is performed again in a second pass taking intoaccount the changed effective depths of sections calculated on the basis of reinforcementprovided after the preliminary design. Final provisions of flexural reinforcements are madethen. Efforts have been made to meet the guideline for the curtailment of reinforcements asper the DIN code. Although exact curtailment lengths are not mentioned explicitly in thedesign output (finally which will be more or less guided by the detailer taking into accountof other practical considerations), the user has the choice of printing reinforcements providedby STAAD at 13 equally spaced sections from which the final detailed drawing can beprepared.

10A.4.2 Design for Shear and Torsion

Shear design in STAAD conforms to the specifications of section 17.5 of DIN 1045. Shearreinforcement is calculated to resist both shear forces and torsional moments. Shear andtorsional design is performed at the start and end sections of the member at a distance "d"away from the node of the member where "d" is the effective depth calculated from flexuraldesign. The maximum shear forces from amongst the active load cases and the associatedtorsional moments are used in the design. The capacity of the concrete in shear and torsion isdetermined at the location of design and the balance, if any, is carried by reinforcement. It isassumed that no bent-up bars are available from the flexural reinforcement to carry and

407— STAAD.Pro

10A. German Codes - Concrete Design Per DIN 1045

"balance" shear. Two-legged stirrups are provided to take care of the balance shear forces actingon these sections. Stirrups are assumed to be U-shaped for beams with no torsion, and closedhoops for beams subject to torsion.

10A.4.3 Example of Input Data for Beam Design

UNIT NEWTON MMS


CODE GERMAN

FYMAIN 415 ALL

FYSEC 415 ALL

FC 35 ALL

CLEAR 25 MEM 2 TO 6



DESIGN BEAM 2 TO 9

END CONCRETE DESIGN

10A.5 Column DesignColumns are designed for axial forces and biaxial moments at the ends. All active load casesare tested to calculate reinforcement. The loading which yields maximum reinforcement iscalled the critical load. The requirements of DIN 1045-figure 13, for calculating the equilibriumequations for rectangular and circular sections from first principles, is implemented in thedesign. The user has control of the effective length (sk) in each direction by using the ELZ andELY parameters as described on Table 8A.1. This means that the slenderness will be evaluatedalong with 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 and rectangularcolumns are designed with reinforcement distributed on all four sides equally. That means thetotal number of bars will always be a multiple of four (4). This may cause slightly conservativeresults in some cases. The TRACK parameter may be used to obtain the design details in variouslevels of detail.

Example of Input Data for Column Design

UNIT NEWTON MMS


CODE GERMAN

FYMAIN 415 ALL

FC 35 ALL




END CONCRETE DESIGN


10A.6 Slab DesignTo design a slab, it must first be modeled using finite elements and analyzed. The commandspecifications are in accordance with Section 5.52 of the Technical Reference Manual. Slabs aredesigned to specifications as described by BAUMANN of MUNICH which is the basis forEurocode 2.

Elements are designed for the moments Mx and My. These moments are obtained from theelement force output (see Chapter 2 of the Technical Reference Manual). The reinforcementrequired to resist the Mx moment is denoted as longitudinal reinforcement and thereinforcement required to resist the My moment is denoted as transverse reinforcement. Thefollowing parameters are those applicable to slab design:

FYMAINYield stress for all reinforcing steel

FCConcrete grade

CLEARDistance from the outer surface of the element to the edge of the bar. This isconsidered the same on both top and bottom surfaces of the element.

SRAParameter which denotes the angle of direction of the required transversereinforcement relative to the direction of the longitudinal reinforcement for thecalculation of BAUMANN design forces.

The other parameters shown in Table 10A.1 are not applicable to slab design.

10A.6.1 BAUMANN equations

If the default value of zero is used, the design will be based on Mx and My forces which areobtained from the STAAD analysis. The SRA parameter (Set Reinforcement Angle) can bemanipulated to introduce resolved BAUMANN forces into the design replacing the pure Mxand My moments. These new design moments allow the Mxy moment to be considered whendesigning the section, resolved as an axial force. Orthogonal or skew reinforcement may beconsidered. If SRA is set to -500, an orthogonal layout will be assumed. If however a skew isto be considered, an angle is given in degrees measured from the local element X axisanticlockwise (positive). The resulting Mx* and My* moments are calculated and shown inthe design format.

The design of the slab considers a fixed bar size of 10 mm in the longitudinal direction and 8mm in the transverse. The longitudinal bar is the layer closest to the slab exterior face.

10A.7 Design ParametersThe program contains a number of parameters which are needed to perform the design.Default parameter values have been selected such that they are frequently used numbers forconventional design requirements. These values may be changed to suit the particular designbeing performed. Table 8A.1 of this manual contains a complete list of the available

409— STAAD.Pro


parameters and their default values. It is necessary to declare length and force units asMillimeter and Newton before performing the concrete design.


ParameterName


CODE - Must be specified as DIN1045.



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.

EFACE 0.0 Face of support location at end ofbeam, measured from the end joint.

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 25 N/mm2 Concrete Yield Stress / cube strength

FYMAIN 420 N/mm2 Yield Stress for main reinforcement(For slabs, it is 500 N/mm2 for bothdirections)

FYSEC 420 N/mm2 Yield Stress for secondaryreinforcement a. Applicable to shearand torsion reinforcement in beams

Table 10A.1-German Concrete Design Parameters


ParameterName


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


MINSEC 8 mm Minimum secondary reinforcement barsize. Applicable to shear and torsionreinforcement in beams.

MMAG 1.0 Factor by which column designmoments are magnified for columndesign

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

SFACE 0.0 Face of support location at start ofbeam, measured from the start joint.(Only applicable for shear - useMEMBER OFFSET for bending)

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

-500 = Orthogonal reinforcementlayout considering Mxy

A = Skew angle considered inBAUMANN equations. A is the anglein degrees.

411 — STAAD.Pro


ParameterName


TRACK 0.0 Level of detail in output

0. Critical Moment will not beprinted with beam designreport.

1. For beam gives min/max steel %and spacing. For columns givesa detailed table of output withadditional moments calculated.

2. For beams gives area of steelrequired at intermediatesections. (see NSECTION)

WIDTH ZD Width of concrete member. This valuedefault is as provided as ZD in MEMBERPROPERTIES.


413— STAAD.Pro

10B. German Codes - Steel Design Per the DIN CodeSTAAD.Pro is capable of performing concrete design based on the German code DIN 18800,Parts 1 & 2: Stahlbauten - Teil 1: Bemessung und Konstruktion (Steel structures - Part 1: Designand construction) and Stahlbauten - Teil 2: Stabilitätsfälle - Knicken von Stäben undStabwerken (Steel structures - Part 2: Analysis of safety against buckling of linear membersand frames)

Design of members per DIN 18800 requires the STAAD Eurozone Design Codes SELECT CodePack.

10B.1 GeneralThis section presents some general statements regarding the implementation of the DIN code.The design philosophy and procedural logistics are based on the principles of elastic analysisand allowable stress design. Facilities are available for member selection as well as codechecking. Two major failure modes are recognized: failure by overstressing and failure bystability considerations. The following sections describe the salient features of the designapproach.

Members are proportioned to resist the design loads without exceedance of the allowablestresses or capacities and the most economical section is selected on the basis of the leastweight criteria. The code checking part of the program also checks the slendernessrequirements and the stability criteria. It is recommended that you use the following steps inperforming 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.

10B.2 AnalysisMethodologyElastic analysis method is used to obtain the forces and moments for design. Analysis is donefor the primary and combination loading conditions provided by the user. The user is allowedcomplete flexibility in providing loading specifications and in using appropriate load factors tocreate necessary loading situations. Depending upon the analysis requirements, regularstiffness analysis or P-Delta analysis may be specified. Dynamic analysis may also be performedand the results combined with static analysis results.

10B.3 Member Property SpecificationsFor specification of member properties of standard German steel sections, the steel sectionlibrary available in STAAD may be used. The next section describes the syntax of commandsused to assign properties from the built-in steel table. Member properties may also be specifiedusing the User Table facility. For more information on these facilities, refer to Section 1.7 theSTAAD Technical Reference Manual.


10B.4 Built-in German Steel Section LibraryThe following information is provided for use when the built-in steel tables are to bereferenced for member property specification. These properties are stored in a database file. Ifcalled for, these properties are also used for member design. Since the shear areas are builtinto these tables, shear deformation is always considered for these members during theanalysis. An example of member property specification in an input file is provided at the endof this section.

A complete listing of the sections available in the built-in steel section library may beobtained using the tools of the graphical user interface.



10B.4.1 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

10B.4.2 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

10B.4.3 I Shapes

I shapes are identified by the depth of the section. The following example illustrates thedesignation.

14 15 TA ST I200 (INDICATES AN I-SECTION WITH 200MM DEPTH)

10B.4.4 T Shapes

Tee sections are not input by their actual designations, but instead by referring to the I beamshapes from which they are cut. For example,

1 5 TA T HEA220

2 8 TA T IPE120

415— STAAD.Pro

10B. German Codes - Steel Design Per the DIN Code

10B.4.5 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 of260mm.

11 TA D U70X40

27 TA D U260


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., D U180. The spacingbetween the double channels is provided following the expression “SP”.

11 TA D U180

27 TA D U280 SP 0.5 (INDICATES 2 CHANNELS BACK-TO-BACK SPACED AT0.5 LENGTH UNITS)

10B.4.7 Angles

Two types of specifications may be used to describe an angle. The standard angle section isspecified as follows:

16 20 TA ST L20X20X2.5

The above section signifies an angle with legs of length 20mm and a leg thickness of 2.5mm.The above specification may be used when the local z-axis corresponds to the Z-Z axis specifiedin Chapter 2. If the local y-axis corresponds to the Z-Z axis, type specification "RA" (reverseangle) may be used.

17 21 TA RA L40X20X5


Short leg back-to-back or long leg back-to-back double angles can be specified by using theword SD or LD, respectively, in front of the angle size. In case of an equal angle, either SD orLD will serve the purpose. Spacing between the angles is provided by using the word SP andthe spacing value following the section name.

14 TO 20 TA SD L40X20X4 SP 0.5

21 TO 27 TA LD L40X20X4 SP 0.5



To designate circular hollow sections, use PIP followed by numerical value of the diameterand thickness of the section in mm omitting the decimal section of the value provided fordiameter. The following example will illustrate the designation.

8 TO 28 TA ST PIP602.9 (60.3MM DIA, 2.9MM WALL THICKNESS)

3 64 67 TA ST PIP40612.5 (406.4MM DIA, 12.5MM WALL THICKNESS)



specifies a pipe with outside dia. of 25 and inside dia. of 20 in current length units. Only codechecking and no member selection will be performed if this type of specification is used.


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 wall thickness of3.6mm.

Tubes, like pipes can also be input by their dimensions (Height, Width and Thickness)instead of by their table designations.


is a tube that has a height of 8, a width of 6, and a wall thickness of 0.5 in current lengthunits. Only code checking and no member selection will be performed for TUBE sectionsspecified this way.

10B.4.11 Example

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

417— STAAD.Pro


* IPE SHAPES

1 TA ST IPEA120

* HE SHAPES

2 TA ST HEB300

* I SHAPES

3 TA ST I200

* T SHAPES

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 TO BACK

9 TA LD L40X20X4 SP 0.5

* DOUBLE ANGLES - SHORT LEGS BACK TO BACK

10 TA SD L40X20X4 SP 0.5

* PIPES

11 TA ST PIP602.9

* PIPES


* TUBES

13 TA ST TUB100603.6

* TUBES

14 TA ST TUBE DT 8.0 WT 6.0 WT 0.5

*


FINISH

10B.5 Member CapacitiesThe allowable stresses used in the implementation are based on DIN 18800 (Part 1) - Section 7.The procedures of DIN 18800 Part 2 are used for stability analysis. The basic measure ofmember capacities are the allowable stresses on the member under various conditions ofapplied loading such as allowable tensile stress, allowable compressive stress etc. These dependon several factors such as cross sectional properties, slenderness factors, unsupported width tothickness ratios and so on. Explained here is the procedure adopted in STAAD for calculatingsuch capacities.


10B.5.1 Checks for Axial Tension

In members with axial tension, the tensile load must not exceed the tension capacity of themember. The tension capacity of the member is calculated on the basis of the member area.STAAD calculates the tension capacity of a given member based on a user supplied netsection factor (NSF -a default value of 1.0 is present but may be altered by changing the inputvalue, see Table 8B.1) and proceeds with member selection or code checking.

10B.5.2 Checks for Axial Compression

The compression capacity for members in compression is determined according to theprocedure of DIN 18800- Part 2. Compressive resistance is a function of the slenderness of thecross-section (Kl/r ratio) and the user may control the slenderness value by modifyingparameters such as KY, LY, KZ and LZ.

10B.5.3 Checks for Bending and Shear

The bending compressive and tensile capacities are dependent on such factors as length ofoutstanding legs, thickness of flanges, unsupported length of the compression flange (UNL,defaults to member length) etc. Shear capacities are a function of web depth, web thicknessetc. Users may use a value of 1.0 or 2.0 for the TRACK parameter to obtain a listing of thebending and shear capacities.

10B.6 Combined LoadingFor members experiencing combined loading (axial force, bending, and shear), applicableinteraction formulas are checked at different locations of the member for all modeled loadingsituations. Members subjected to axial force and bending are checked using the criteria ofDIN 18800 (Part 1) - Section 6.1.6. In addition, for members with axial loads and bending, thecriteria of DIN 18800(Part 2) - Sections 3.4 and 3.5 are used.

10B.7 Design ParametersYou are allowed complete control over the design process through the use of parametersdescribed in the following table. These parameters communicate design decisions from theengineer to the program. The default parameter values have been selected such that they arefrequently used numbers for conventional design. Depending on the particular designrequirements of the situation, some or all of these parameter values may have to be changedto exactly model the physical structure.


419— STAAD.Pro


ParameterName


CODE - Must be specified as DIN18800.



BEAM 0.0 Number of sections to be checked permember:

0. Design only for end sections.

1. Check at location of maximumMZ along member.

2. Check ends plus location ofbeam 1.0 check.

3. Check at every 1/13th of themember length and report themaximum.

CB 0 Beam coefficient n, defined in Table 9:If Cb = 0, program will use n = 2.5 forrolled sections and 2.0 for weldedsections.

CMM 1.0 Moment factor, Zeta, defined in Table10:

1. fixed ended member withconstant moment, Zeta = 1.0

2. pin ended member with UDL,Zeta = 1.12

3. pin ended member with centralpoint load, Zeta = 1.35

4. fixed ended member, Zetacalculated 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, this isthe minor axis.

Table 10B.1-German Steel Design Parameters


ParameterName


KZ 1.0 K value in local z-axis. Usually, this isthe major axis.

LY MemberLength

Length in local y-axis to calculateslenderness ratio.

LZ MemberLength

Length in local z-axis to calculateslenderness ratio.

PY 240 N/sq.mm Strength of steel.


RATIO 1.0 Permissible ratio of actual to allowablestresses

SAME 0.0 Control of sections to try during aSELECT process:

0. Try every section of the sametype as the original.

1. Try only those with a similarname.

SBLT 0 Specify section as either rolled or built-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 results plusmember capacities

2. Output detailed results

UNF 1.0 Same as above provided as a factor ofactual member length.

421 — STAAD.Pro


ParameterName


UNL MemberLength

Unrestrained member length in lateraltorsional buckling checks.

10B.8 Code CheckingThe purpose of code checking is to check whether the provided section properties of themembers are adequate to carry the forces transmitted to it by the loads on the structure. Theadequacy is checked per the DIN requirements.

Code checking is done using forces and moments at specified sections of the members. If theBEAM parameter for a member is set to 1, moments are calculated at every twelfth point alongthe beam, and the maximum moment about the major axis is used. When no sections arespecified and the BEAM parameter is set to zero (default), design will be based on memberstart and end forces. The code checking output labels the members as PASSed or FAILed. Inaddition, the critical condition, governing load case, location (distance from start joint) andmagnitudes of the governing forces and moments are also printed.


10B.9 Member SelectionThe member selection process basically involves determination of the least weight memberthat PASSes the code checking procedure based on the forces and moments of the most recentanalysis. The section selected will be of the same type as that specified initially. For example, amember specified initially as a channel will have a channel selected for it. Selection ofmembers whose properties are originally provided from a user table will be limited to sectionsin the user table. Member selection cannot be performed on TUBES, PIPES, or members listedas PRISMATIC.


Sample Input data for Steel Design

UNIT METER

PARAMETER

CODE GERMAN

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

423— STAAD.Pro


Section 11

Indian Codes


425— STAAD.Pro

11A. Indian Codes - Concrete Design per IS 456STAAD.Pro is capable of performing concrete design based on the Indian code IS 456 2000Code of Practice for Plain and Reinforced Concrete.

Design of members per IS 456 requires the STAAD India Design Codes SELECT Code Pack.


l For Beams — Prismatic (Rectangular & Square), T-Beams, and L-shapes



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 are rectangular (450 mmdepth and 250mm width) and the second set of members, with only depth and no widthprovided, will be assumed to be circular with 350 mm diameter. The third set numbers in theabove example represents a T-shape with 750 mm flange width, 200 width, 400 mm overalldepth and 100 mm flange depth (See section 6.20.2). The program will determine whether thesection is rectangular, flanged or circular and the beam or column design.

11A.3 Design ParametersThe program contains a number of parameters which are needed to perform design as perIS:456(2000). Default parameter values have been selected such that they are frequently usednumbers for conventional design requirements. These values may be changed to suit theparticular design being performed. Table 9A.1 of this manual contains a complete list of theavailable parameters and their default values. It is necessary to declare length and force unitsas Millimeter and Newton before performing the concrete design.



ParameterName


CODE - Must be specified as INDIAN.



BRACING 0.0 Beam Design:

A value of 1.0 means theeffect of axial force willbe taken into accountfor beam design.

Column Design:

correspond to the terms"Braced" and "Unbraced"described in Notes 1, 2,and 3 of Clause 39.7.1 ofIS456:2000.

1. The column is unbraced aboutmajor axis.

2. The column is unbraced aboutminor axis.

3. The column is unbraced aboutboth axis.

CLEAR 25 mm

40 mm

For beam members.

For column members

DEPTH YD Total depth to be used for design. Thisvalue defaults to YD as provided underMEMBER PROPERTIES.

EFACE 0.0 Face of support location at end ofbeam. The parameter can also be usedto check against shear at any pointfrom the end of the member.

Note: Both SFACE and EFACE areinput as positive numbers.

Table 11A.1-Indian Concrete Design IS456 Parameters

427— STAAD.Pro

11A. Indian Codes - Concrete Design per IS 456

ParameterName


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 against enhancedshear strength as per Cl. 40.5 ofIS456:2000.

l ENSH = 1.0 means ordinaryshear check to be performed ( no enhancement of shearstrength at sections close tosupport)

l For ENSH = a positive value(sayx ), shear strength will beenhanced up to a distance xfrom the start of the member.This is used only when a spanof a beam is subdivided intotwo or more parts. (Refer note )

l For ENSH = a negative value(say –y), shear strength will beenhanced up to a distance yfrom the end of the member.This is used only when a spanof a beam is subdivided intotwo or more parts.(Refer note)

If default value (0.0) is used theprogram will calculate Length toOverall Depth ratio. If this ratio isgreater than 2.5, shear strength will beenhanced at sections (<2d) close tosupport otherwise ordinary shearcheck will be performed.

FC 30 N/mm2 Concrete Yield Stress.

FYMAIN 415 N/mm2 Yield Stress for main reinforcing steel.


ParameterName


FYSEC 415 N/mm2 Yield Stress for secondary reinforcingsteel.

MINMAIN 10 mm Minimum main reinforcement barsize.

MAXMAIN 60 mm Maximum main reinforcement barsize.

MINSEC 8 mm Minimum secondary reinforcementbar size.

MAXSEC 12 mm Maximum secondary reinforcementbar size.

RATIO 4.0 Maximum percentage of longitudinalreinforcement in columns.

REINF 0.0 Tied column. A value of 1.0 will meanspiral reinforcement.

RENSH 0.0 Distance of the start or end point ofthe member from its nearest support.This parameter is used only when aspan of a beam is subdivided into twoor 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 against shearat the face of the support in beamdesign. The parameter can also beused to check against shear at anypoint from the start of the member.

SPSMAIN 25 mm Minimum clear distance betweenmain reinforcing bars in beam andcolumn. For column center to centerdistance between main bars cannotexceed 300 mm.

429— STAAD.Pro


ParameterName


TORSION 0.0 0. torsion to be considered inbeam design.

1. torsion to be neglected in beamdesign.

TRACK 0.0 Beam Design:

0. output consists ofreinforcement details at START,MIDDLE, and END.

1. critical moments are printed inaddition to TRACK 0.0 output.

2. required steel for intermediatesections defined by NSECTIONare printed in addition toTRACK 1.0 output.

Column Design:

0. reinforcement details areprinted.

1. column interaction analysisresults are printed in additionto TRACK 0.0 output.

2. a schematic interactiondiagram and intermediateinteraction values are printedin addition to TRACK 1.0output.

ULY 1.0 Ratio of unsupported length to actuallength of column about minor axis.See Note c below.

ULZ 1.0 Ratio of unsupported length to actuallength of column about major axis.See Note c below.

WIDTH ZD Width to be used for design. Thisvalue defaults to ZD as provided underMEMBER PROPERTIES.


11A.3.1 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 to findwhether it is a short or long column. Please refer CL 25.1.2 of IS456:2000.

In CL 25.1.2 of IS456:2000, you will find two term, lex and ley, which STAAD calculatesas:

l lex = ELZ multiplied by the member length (distance between the two nodes ofthe member)

l ley = ELY multiplied by the member length (distance between the two nodes ofthe member)

For the term "D" in CL 25.1.2 of IS456:2000, STAAD uses the YD dimension of thecolumn.

For the term "b" in CL 25.1.2 of IS456:2000, STAAD uses the ZD dimension of thecolumn.

c. ULY and ULZ parameters are used to calculate unsupported length of column to findminimum eccentricity. Please refer CL 25.4 of IS456:2000.

In CL 25.4 of IS456:2000, you will find an expression "unsupported length of column".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 the span ofa beam is subdivided into two or more parts. When this condition occurs, the RENSHparameter is also to be used.

The span of the beam is subdivided four parts, each of length L meter. The shearstrength will be enhanced up to X meter from both supports. The input should be thefollowing:

Steps:

1. ENSH L MEMB 1 => Shear strength will be enhanced throughout the lengthof the member 1, positive sign indicates length measured from start of the

431 — STAAD.Pro


member

2. ENSH (X-L) MEMB 2 => Shear strength will be enhanced up to a length (X-L) ofthe member 2, length measured from the start of the member

3. ENSH –L MEMB 4 => Shear strength will be enhanced throughout the lengthof the member 4, negative sign indicates length measured from end of themember

4. ENSH –(X-L) MEMB 3 => Shear strength will be enhanced up to a length (X-L) ofthe member 3, length measured from the end of the member

5. RENSH L MEMB 2 3 => Nearest support lies at a distance L from both themembers 2 and 3.

6. DESIGN BEAM 1 TO 4=> This will enhance the shear strength up to length Xfrom both ends of the beam consisting of members 1 to 4 and gives spacingaccordingly.

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

where τc, enhanced = 2dτc/av

At section 0.0, av becomes zero. Thus enhanced shear strength will become infinity.However for any section shear stress cannot exceed τc, max. Hence enhanced shearstrength is limited to a maximum value of τc, max.

11A.4 Slenderness Effects and Analysis ConsiderationSlenderness effects are extremely important in designing compression members. The IS:456code specifies two options by which the slenderness effect can be accommodated (Clause 39.7).One option is to perform an exact analysis which will take into account the influence of axialloads and variable moment of inertia on member stiffness and fixed end moments, the effectof deflections on moment and forces and the effect of the duration of loads. Another option isto approximately magnify design moments.

STAAD has been written to allow the use of the first option. To perform this type of analysis,use the command PDELTA ANALYSIS instead of PERFORM ANALYSIS. The P-Delta analysis willaccommodate all requirements of the second- order analysis described by IS:456, except for theeffects of the duration of the loads. It is felt that this effect may be safely ignored becauseexperts believe that the effects of the duration of loads are negligible in a normal structuralconfiguration.

Although ignoring load duration effects is somewhat of an approximation, it must be realized that the approximate evaluation of slenderness effects is also an approximate method. In thismethod, additional moments are calculated based on empirical 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 beenimplemented in STAAD.Pro. They will be checked if the ELY and ELZ parameters arespecified.

Considering all these information, a P-Delta analysis, as performed by STAAD may be used forthe design of concrete members.

Note: 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 and moments(i.e., analysis results), whereas a primary load case is revised during the P-deltaanalysis based on the deflections. Loads can be combined prior to analysis usingthe REPEAT LOAD command.

Note: You must specify the appropriate load factors (e.g., 1.5 for dead load, etc.) as STAADdoes not factor the loads automatically.

11A.5 Beam DesignBeams are designed for flexure, shear and torsion. If required the effect the axial force may betaken into consideration. For all these forces, all active beam loadings are prescanned toidentify the critical load cases at different sections of the beams. The total number of sectionsconsidered is 13 (e.g., 0., .1, .2, .25, .3, .4, .5, .6, .7, .75, .8, .9, and 1). All of these sections arescanned to determine the design force envelopes.


Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging(creating tensile stress at the top face) moments are calculated for all active load cases at eachof the above mentioned sections. Each of these sections is designed to resist both of thesecritical sagging and hogging moments. Where ever the rectangular section is inadequate assingly reinforced section, doubly reinforced section is tried. However, presently the flangedsection is designed only as singly reinforced section under sagging moment. It may also benoted all flanged sections are automatically designed as rectangular section under hoggingmoment as the flange of the beam is ineffective under hogging moment. Flexural design ofbeams is performed in two passes. In the first pass, effective depths of the sections aredetermined with the assumption of single layer of assumed reinforcement and reinforcementrequirements are calculated. After the preliminary design, reinforcing bars are chosen fromthe internal database in single or multiple layers. The entire flexure design is performed againin a second pass taking into account of the changed effective depths of sections calculated onthe basis of reinforcement provide after the preliminary design. Final provisions of flexuralreinforcements are made then. Efforts have been made to meet the guideline for thecurtailment of reinforcements as per IS:456-2000 (Clause 26.2.3). Although exact curtailmentlengths are not mentioned explicitly in the design output (finally which will be more or lessguided by the detailer taking into account of other practical consideration), user has the

433— STAAD.Pro


choice of printing reinforcements provided by STAAD at 11 equally spaced sections from whichthe final detail drawing can be prepared.


Shear reinforcement is calculated to resist both shear forces and torsional moments. Sheardesign are performed at 11 equally spaced sections (0.0 to 1.0) for the maximum shear forcesamongst the active load cases and the associated torsional moments. Shear capacity calculationat different sections without the shear reinforcement is based on the actual tensilereinforcement provided by STAAD program. Two-legged stirrups are provided to take care ofthe balance shear forces acting on these sections.

As per Clause 40.5 of IS:456-2000 shear strength of sections (< 2d where d is the effectivedepth) close to support has been enhanced, subjected to a maximum value of τcmax.

11A.5.3 Beam Design Output

The default design output of the beam contains flexural and shear reinforcement provided at5 equally spaced (0, .25, .5, .75 and 1.) sections along the length of the beam. User has option toget a more detail output. All beam design outputs are given in IS units. An example ofrectangular beam design output with TRACK 2.0 output is presented below:

B E A M N O. 1 D E S I G N R E S U L TS

M20 Fe415 (Main) Fe250(Sec.)

LENGTH: 6400.0 mm SIZE: 300.0 mm X 400.0 mmCOVER: 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 | 50.510.00 1

| 0.00 0.00 0.00 1 |1066.7 | 0.00 53.88 0.00 1 | 40.41

0.00 1| 0.00 0.00 0.00 1 |

1600.0 | 0.00 72.73 0.00 1 | 30.310.00 1

| 0.00 0.00 0.00 1 |2133.3 | 0.00 86.20 0.00 1 | 20.20

0.00 1| 0.00 0.00 0.00 1 |


2666.7 | 0.00 94.28 0.00 1 | 10.100.00 1

| 0.00 0.00 0.00 1 |3200.0 | 0.00 96.98 0.00 1 | 0.00

0.00 1| 0.00 0.00 0.00 1 |

3733.3 | 0.00 94.28 0.00 1 | -10.100.00 1

| 0.00 0.00 0.00 1 |4266.7 | 0.00 86.20 0.00 1 | -20.20

0.00 1| 0.00 0.00 0.00 1 |

4800.0 | 0.00 72.73 0.00 1 | -30.310.00 1

| 0.00 0.00 0.00 1 |5333.3 | 0.00 53.88 0.00 1 | -40.41

0.00 1| 0.00 0.00 0.00 1 |

5866.7 | 0.00 29.63 0.00 1 | -50.510.00 1

| 0.00 0.00 0.00 1 |6400.0 | 0.00 0.00 0.00 1 | -60.61

0.00 1| 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. |

(2 legged)---------------------------------------------------------------

-------------0.0 | 0.00/ 402.12( 2-16í )| 0.00/ 981.75( 2-25í )|

8í @ 180 mm533.3 | 0.00/ 402.12( 2-16í )| 237.32/1472.62( 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 mm2133.3 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )|

8í @ 180 mm2666.7 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )|

8í @ 180 mm3200.0 | 0.00/ 402.12( 2-16í )| 894.99/1472.62( 3-25í )|

8í @ 180 mm3733.3 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )|

8í @ 180 mm4266.7 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )|

8í @ 180 mm

435— STAAD.Pro


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

----------------------------------------------------------------------------

11A.6 Column DesignColumns are designed for axial forces and biaxial moments at the ends. All active load casesare tested to calculate reinforcement. The loading which yield maximum reinforcement iscalled the critical load. Column design is done for square, rectangular and circular sections. Bydefault, square and rectangular columns and designed with reinforcement distributed on eachside equally for the sections under biaxial moments and with reinforcement distributedequally in two faces for sections under uniaxial moment. User may change the defaultarrangement of the reinforcement with the help of the parameter RFACE (see Table 8A.1).Depending upon the member lengths, section dimensions and effective length coefficientsspecified by the user STAAD automatically determine the criterion (short or long) of thecolumn design. All major criteria for selecting longitudinal and transverse reinforcement asstipulated by IS:456 have been taken care of in the column design of STAAD. Default clearspacing between main reinforcing bars is taken to be 25 mm while arrangement oflongitudinal bars.

11A.6.1 Column Design Output

Default column design output (TRACK 0.0) contains the reinforcement provided by STAADand the capacity of the section. With the option TRACK 1.0, the output contains intermediateresults such as the design forces, effective length coefficients, additional moments etc. Alldesign output is given in SI units. An example of a TRACK 2.0 output follows:



LENGTH: 3000.0 mm CROSS SECTION: 400.0 mm X 600.0 mmCOVER: 40.0 mm

** GUIDING LOAD CASE: 1 END JOINT: 1 SHORT COLUMN

DESIGN FORCES (KNS-MET)-----------------------DESIGN AXIAL FORCE (Pu) : 2000.00

About ZAbout Y

INITIAL MOMENTS : 160.00120.00

MOMENTS DUE TO MINIMUM ECC. : 52.0040.00

SLENDERNESS RATIOS : - -MOMENTS DUE TO SLENDERNESS EFFECT : - -


MOMENT REDUCTION FACTORS : - -ADDITION MOMENTS (Maz and May) : - -

TOTAL DESIGN MOMENTS : 160.00120.00

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 @ 190mm c/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

==================================================================-==========

11A.7 Bar CombinationInitially the program selects only one bar to calculate the number of bars required and area ofsteel provided at each section along the length of the beam. You may use theBAR COMBINATION command to specify two bar diameters to calculate a combination of eachbar to be provided at each section. The syntax for bar combination is given below.

START BAR COMBINATION

MD1 <bar diameter> MEMB <member list>


END BAR COMBINATION

Note: The bar sizes should be specified in the order of increasing size (i.e., MD2 bardiameter should be greater than MD1 bar diameter).

The beam length is divided into three parts, two at its ends and one at span. Ld gives thedevelopment 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|

437— STAAD.Pro


----------------------------------------------------------------------------

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 |


Ast Reqd| 632.82 | 894.99 |632.82 |

Prov| 804.57 | 1384.43 |804.57 |

Ld (mm) | 752.2 | 1175.3 |752.2 |

----------------------------------------------------------------------------

===================================================================-=========

11A.8 Wall Design in accordance with IS 456-2000The design of walls in accordance with IS 456-2000 is available in STAAD.Pro.

The design is performed for in-plane shear, in-plane & out-of-plane bending, and out-of-planeshear. The wall has to be modeled using STAAD’s Surface elements (Refer to Section 5.13.3 ofthe Technical Reference Manual). The use of the Surface element enables the designer to treatthe entire wall as one entity. It greatly simplifies the modeling of the wall and adds clarity tothe analysis and design output. The results are presented in the context of the entire wallrather than individual finite elements thereby allowing users to quickly locate requiredinformation.

The program reports shear wall design results for each load case/combination for the specifiednumber of sections given in the SURFACE DIVISION command (default value is 10) command.The shear wall is designed at these horizontal sections. The output includes the requiredhorizontal and vertical distributed reinforcing, the concentrated (in-plane bending) edgereinforcing and the link required for out-of-plane shear.


Refer to Section 5.55 of the Technical Reference Manual for additional details on shear walldesign.

11A.8.1 Design Parameters


CODE INDIAN

shearwall-parameters

DESIGN SHEARWALL LIST shearwall-list

END

The following table explains the parameters used in the shear wall design.


ParameterName


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.

Table 11A.2-Shear Wall Design Parameters

439— STAAD.Pro


ParameterName


HMIN 8 Minimum size ofhorizontal 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 Reinforcement placementmode:

0. single layer, eachdirection

1. two layers, eachdirection


ParameterName


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.

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

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

3. The SUPPORTS command includes the new support generation routine. For instance,the line 2 to 5 gen pin assigns pinned supports to all nodes between nodes 2 and 5.As the node-to-node distances were previously subdivided by the SET DIVISION 12command, there will be an additional 11 nodes between nodes 2 and 5. As a result, all13 nodes will be assigned pinned supports. Please note that the additional 11 nodes arenot individually accessible to the user. They are created by the program to enable thefinite element mesh generation and to allow application of boundary constraints.

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

5. The shear wall design commands are listed between lines START SHEARWALL DES andEND. The CODE command selects the design code that will be the basis for the design.For Indian code the parameter is INDIAN. The DESIGN SHEARWALL LIST command isfollowed by a list of previously defined Surface elements intended as shear walls and/orshear wall components.

11A.8.2 Technical Overview

The program implements provisions of section 32 of IS 456-2000 and relevant provisions asreferenced therein, for all active load cases. The following steps are performed for each of thehorizontal sections of the wall.

Checking of slenderness limit

The slenderness checking is done as per clause no. 32.2.3. The default effective height is theheight of the wall. User can change the effective height. The limit for slenderness is taken as

441 — STAAD.Pro


30.

Design for in-plane bending and vertical load

(denoted by Mz & Fy in the shear wall force output)

Walls when subjected to combined in-plane horizontal and vertical forces produce in-planebending in conjunction with vertical load. According to clause no. 32.3.1, in-plane bendingmay be neglected in case a horizontal cross section of the wall is always under compressiondue combined effect of horizontal and vertical loads. Otherwise, the section is checked forcombined vertical load and in-plane moment as column with axial load and uni-axialbending. For this purpose, the depth is taken as 0.8 x horizontal length of wall and breadth isthe thickness of the wall. The reinforcement is concentrated at both ends (edges) of the wall.The edge reinforcement 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). Maximum4% reinforcement is allowed.

Design for in-plane shear

(denoted by Fxy in the shear wall force output)

By default, the program does not design only at the critical section but at all the horizontalsections. By suitable use of the surface division command, design at critical section as perclause no. 32.4.1 can be performed.

The design for in-plane shear is done as per clause no. 32.4. The nominal shear stress iscalculated as per clause no. 32.4.2 and it is checked with the maximum allowable shear stressas per clause no. 32.4.2.1. The design shear strength of concrete is calculated as per clause no.32.4.3. Design of shear reinforcement is done as per clause no. 32.4.4. Minimum reinforcementsare as per clause no. 32.5.

Design for vertical load and out-of-plane vertical bending

(denoted by Fy and My respectively in the shear wall force output)

Apart from the in-plane bending and horizontal shear force, the wall is also subjected to out-of-plane bending in the vertical and horizontal directions. The part of the wall which is nothaving edge reinforcements (i.e., a zone of depth 0.6 x Length of the wall), is designed again ascolumn under axial load (i.e., vertical load) and out-of-plane vertical bending. The minimumreinforcements and maximum allowable spacings of reinforcements are as per clause no. 32.5

Design for out-of-plane horizontal bending

(denoted by Mx in the shear wall force output)

The horizontal reinforcement which is already provided for in-plane shear is checked againstout-of-plane horizontal bending. The wall is assumed as a slab for this purpose.

Design for out-of-plane shears

(denoted by Qx and Qy in the shear wall force output)


The out-of-plane shear arises from out-of-plane loading. The nominal shear stresses arecalculated as per clause no. 40.1. Maximum allowable shear stresses are as per table 20. Forshear force in the vertical direction, shear strength of concrete section is calculated as persection 4.1 of SP 16 : 1980 considering vertical reinforcement as tension reinforcement.Similarly, for shear force in the horizontal direction, shear strength of concrete section iscalculated considering horizontal reinforcement as tension reinforcement. Shearreinforcements in the form of links are computed as per the provisions of clause no. 40.4.

11A.8.3 Example

The following example illustrates the input for the definition of shear wall and design of thewall.

…

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 2.17185E+007

POISSON 0.17

DENSITY 23.5616

ALPHA 1E-005

…

START SHEARWALL DES

CODE INDIAN

UNIT NEW MMS

FC 25

FYMAIN 415

TWO 1

443— STAAD.Pro


VMIN 12

HMIN 12

EMIN 12

DESIGN SHEA LIST 1 TO 4

END

11A.8.4 Shear Wall Design With Opening

The Surface element has been enhanced to allow design of shear walls with rectangularopenings. The automatic meshing algorithm has been improved to allow variable divisionsalong wall and opening(s) edges. Design and output are available for user selected locations.

Shear walls modeled in STAAD.Pro may include an unlimited number of openings. Due to thepresence of openings, the wall may be comprise of different wall panels of varying types.

1. Shear wall set-up

Definition of a shear wall starts with a specification of the surface element perimeternodes, meshing divisions along node-to-node segments, opening(s) corner coordinates,and meshing divisions of four edges of the opening(s).

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

RECOPENING x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4 DIVISION od1, ..., 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-node distanceon 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 all node-to-nodesegments, or if any of the numbers listed equals zero, then the correspondingdivision number is set to the default value (=10, or as previously input by theSET DIVISION command).

Default locations for stress/force output, design, and design output are set as 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 of thesurface where output is requested. The output is provided for sectionslocated between division segments. For example, if the number of divisions= 2, then the output will be produced for only one section (at the center ofthe edge).

2. Stress/force output printing

Values of internal forces may be printed out for any user-defined section of the 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 the fullcross-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 is directed awayfrom 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 from theSURFACE DIVISION X or SURFACE DIVISION Y input values. If the BETWEENcommand is omitted, the output is generated based on full cross-sectionwidth.

3. Definition of wall panels

Input syntax for panel definition is as follows:

START PANEL DEFINITION

SURFACE i PANEL j WALL x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4

END PANEL DEFINITION

Where:

i = ordinal surface number,

445— STAAD.Pro


j = ordinal panel number,

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 code IS 456.General syntax of the design command is as follows:


(…)

DESIGN SHEARWALL (AT f2) LIST s

ENDSHEARWALL DESIGN

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

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 of horizontaland vertical bars provided along edges of openings is equal to that of therespective interrupted bars.

b. Panels have been defined.

Only wall panel design is supported in Indian code.


447— STAAD.Pro

11B. Indian Codes - Concrete Design per IS 13920STAAD.Pro is capable of performing concrete design based on the Indian code IS 13920 Code ofPractice for Ductile Detailing of Reinforced Concrete Structures Subjected to Seismic Forces.Designs per IS 13920 satisfy all provisions of IS 456 – 2000 and IS 13920 for beams and columns(See "Indian Codes - Concrete Design per IS 456" on page 426).

Design of members per IS 1320 requires the STAAD India Design Codes SELECT Code Pack.

11B.1 Design OperationsEarthquake motion often induces force large enough to cause inelastic deformations in thestructure. If the structure is brittle, sudden failure could occur. But if the structure is made tobehave ductile, it will be able to sustain the earthquake effects better with some deflectionlarger than the yield deflection by absorption of energy. Therefore ductility is also required asan essential element for safety from sudden collapse during severe shocks.

11B.2 Section Types for Concrete DesignThe 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)

11B.3 Design ParametersThe program contains a number of parameters that are needed to perform design as per IS13920. It accepts all parameters that are needed to perform design as per IS:456. Over and aboveit has some other parameters that are required only when designed is performed as perIS:13920. Default parameter values have been selected such that they are frequently usednumbers for conventional design requirements. These values may be changed to suit theparticular design being performed. Table 8A1.1 of this manual contains a complete list of theavailable parameters and their default values. It is necessary to declare length and force unitsas Millimeter and Newton before performing the concrete design.


ParameterName


CODE - Must be specified as IS13920



Table 11B.1-Indian Concrete Design IS 13920 Parameters


ParameterName


BRACING 0.0 Beam Design

1.0 = the effect of axial force will betaken into account for beam design.

Column Design: Correspond to theterms "Braced" and "Unbraced"described in Notes 1, 2, and 3 of Clause39.7.1 of IS456:2000.

1.0 = the column is unbraced aboutmajor axis.2.0 = the column is unbraced aboutminor axis.3.0 = the column is unbraced aboutboth axis.

DEPTH YD Total depth to be used for design. Thisvalue defaults to YD (depth of sectionin Y direction) as provided underMEMBER PROPERTIES.

CLEAR 25 mm

40 mm

For beam members.

For column members

Note: This is the clear cover to theoutermost main reinforcingbar. It is not the clear coverfor the stirrups or the tiebars.

449— STAAD.Pro

11B. Indian Codes - Concrete Design per IS 13920

ParameterName


COMBINE 0.0 Default value means there will be nomember combination.

1.0 = no printout ofsectional force andcritical load forcombined member in theoutput.

2.0 = printout of sectionalforce for combinedmember in the output.

3.0 = printout of bothsectional force andcritical load forcombined member in theoutput. ***

EFACE 0.0 Face of support location at end ofbeam. The parameter can also be usedto check against shear at any pointfrom the end of the member.

Note: Both SFACE and EFACE areinput 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.


ParameterName


ENSH 0.0 Perform shear check against enhancedshear strength as per Cl. 40.5 ofIS456:2000.

1.0 = ordinary shear checkto be performed ( noenhancement of shearstrength at sections closeto support)

a positive value(say x ) =shear strength will beenhanced up to adistance x from the startof the member. This isused only when a span ofa beam is subdivided intotwo or more parts. (Refernote after Table 8A.1 )

a negative value(say –y) =shear strength will beenhanced up to adistance y from the endof the member. This isused only when a span ofa beam is subdivided intotwo or more parts.(Refernote after Table 8A.1)

0.0 = the program willcalculate Length toOverall Depth ratio. Ifthis ratio is greater than2.5, shear strength will beenhanced at sections(<2d) close to supportotherwise ordinary shearcheck will be performed.

451 — STAAD.Pro


ParameterName


EUDL None Equivalent u.d.l on span of the beam.This load value must be the unfactoredload on span. During design the loadvalue is multiplied by a factor 1.2. If nou.d.l is defined factored shear force dueto gravity load on span will be taken aszero. No elastic or plastic moment willbe calculated. Shear design will beperformed based on analysis result.(Refer note)

FYMAIN 415 N/mm2 Yield Stress for main reinforcing steel.

FYSEC 415 N/mm2 Yield Stress for secondary reinforcingsteel.

FC 30 N/mm2 Concrete Yield Stress.


ParameterName


GLD None Gravity load number to be consideredfor calculating equivalent u.d.l on spanof the beam, in case no EUDL ismentioned in the input. This loadcasecan be any static loadcase containingMEMBER LOAD on the beam whichincludes UNI, CON, LIN and TRAPmember loading. CMOM memberloading is considered only when it isspecified in local direction. FLOORLOAD is also considered.

The load can be primary orcombination load. For combinationload only load numbers included inload combination is considered. Theload factors are ignored. Internally theunfactored load is multiplied by afactor 1.2 during design.

If both EUDL and GLD parameters arementioned in the input mentionedEUDL will be considered in design

Note: No dynamic (Responsespectrum, 1893, TimeHistory) and moving loadcases are considered.

CMOM member loading in globaldirection is not considered.

UMOM member loading is notconsidered.

HLINK Spacing oflongitudinalbars measuredto the outer

face

Longer dimension of the rectangularconfining hoop measured to its outerface. It shall not exceed 300 mm as perCl. 7.4.8. If the HLINK value as providedin the input file does not satisfy theclause the value will be internallyassumed as the default one. Thisparameter is valid for rectangularcolumn.

453— STAAD.Pro


ParameterName


IPLM 0.0 Default value calculates elastic/plastichogging and sagging moments ofresistance of beam at its ends.

1.0 = calculation ofelastic/plastic hoggingand sagging moments ofresistance of beam to beignored at start node ofbeam. This implies nosupport exists at startnode.

-1.0 = calculation ofelastic/plastic hoggingand sagging moments ofresistance of beam to beconsidered at start nodeof beam. . This impliessupport exists at startnode.

2.0 = calculation ofelastic/plastic hoggingand sagging moments ofresistance of beam to beignored at end node ofbeam. This implies nosupport exists at endnode.

-2.0 = calculation ofelastic/plastic hoggingand sagging moments ofresistance of beam to beconsidered at end nodeof beam. . This impliessupport exists at endnode. **


ParameterName


IMB 0.0 Default value calculates elastic/plastichogging and sagging moments ofresistance of beam at its ends.

1.0 = calculation ofelastic/plastic hoggingand sagging moments ofresistance of beam to beignored at both ends ofbeam. This implies nosupport exist at eitherend of the member.

-1.0 = calculation ofelastic/plastic hoggingand sagging moments ofresistance of beam to beconsidered at both endsof beam. This impliessupport exist at bothends of the member.**

MINMAIN 10 mm Minimum main reinforcement bar size.

MAXMAIN 60 mm Maximum main reinforcement bar size.

MINSEC 8 mm Minimum secondary reinforcement barsize.

MAXSEC 12 mm Maximum secondary reinforcement barsize.

PLASTIC 0.0 Default value calculates elastic hoggingand sagging moments of resistance ofbeam at its ends.

1.0 = plastic hogging andsagging moments ofresistance of beam to becalculated at its ends.

RATIO 4.0 Maximum percentage of longitudinalreinforcement in columns.

REINF 0.0 0.0 = Tied column (default)

1.0 = spiral reinforcement

455— STAAD.Pro


ParameterName


RENSH 0.0 Distance of the start or end point ofthe member from its nearest support.This parameter is used only when aspan of a beam is subdivided into twoor more parts.

Refer note after Table 9A.1

RFACE 4.0 4.0 = longitudinal reinforcement incolumn is arranged equally along fourfaces.

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 against shearat the face of the support in beamdesign. The parameter can also be usedto check against shear at any pointfrom the start of the member.*

Note: Both SFACE and EFACE areinput as positive numbers.*

SPSMAIN 25 mm Minimum clear distance between mainreinforcing bars in beam and column.For column center to center distancebetween main bars cannot exceed 300mm.

TORISION 0.0 0.0 = torsion to be considered in beamdesign.

1.0 = torsion to be neglected in beamdesign.


ParameterName



0.0 = output consists ofreinforcement details atSTART, MIDDLE andEND.

1.0 = critical moments areprinted in addition toTRACK 0.0 output.

2.0 = required steel forintermediate sectionsdefined by NSECTIONare printed in addition toTRACK 1.0 output.

Column Design:

0.0 = reinforcementdetails are printed.

1.0 = column interactionanalysis results areprinted in addition toTRACK 0.0 output.

2.0 = a schematicinteraction diagram andintermediate interactionvalues are printed inaddition to TRACK 1.0output.

ULY 1.0 Ratio of unsupported length to actuallength of column about minor axis.

ULZ 1.0 Ratio of unsupported length to actuallength of column about major axis.

WIDTH ZD Width to be used for design. Thisvalue defaults to ZD as provided underMEMBER PROPERTIES.

Bar combination has been introduced for detailing. Please refer section 9A1.6 for details.

* EFACE and SFACE command is not valid for member combination.

457— STAAD.Pro


** IPLM and IMB commands are not valid for member combination. These commands areignored 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 thisparameter will combine them into one member. It can also be used to combinemembers to form one continuous beam spanning over more than two supports.

2. When two or more members are combined during design plastic or elastic momentswill be calculated at the column supports. At all the intermediate nodes (if any) thiscalculation will be ignored.

Note: Please note that the program only recognizes column at right angle to thebeam. Inclined column support is ignored.

3. It will calculate sectional forces at 13 sections along the length of the combinedmember.

4. It will calculate critical loads (similar to that of Design Load Summary) for all activeload 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 single spanbetween two column supports of a continuous beam is subdivided into severalmembers.

2. Members to be combined should have same constants (E, Poi ratio, alpha, density, andbeta 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 different combinedmembers.

7. The maximum number of members that can be combined into one member is 299.

Note: Sectional forces and critical load for combined member output will only be availablewhen all the members combined are successfully designed in both flexure andshear.

ENSH and RENSH parameters will have to be provided (as and when necessary) even if physicalmember has been formed.


11B.3.1 Example

The following lines show a standard example for design to be performed in IS 13920.

STAAD SPACE

UNIT METER MTON

JOINT COORDINATES

…

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

…… UNI GY -5

LOAD 4 LL

MEMBER LOAD

……. UNI GY -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)

2 1.2 3 1.2 4 1.2

LOAD COMB 9 1.2(DL+LL-SLZ)

459— STAAD.Pro


2 1.2 3 1.2 4 -1.2

PDELTA ANALYSIS

LOAD LIST 5 TO 9


CODE IS13920

UNIT MMS NEWTON

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 8 T/M (DL+LL)I.E., 78.46 NEW/MM

EUDL 78.46 MEMB 110 TO 112

** MEMBERS TO BE COMBINED INTO ONE PHYSICAL MEMBER

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 CONCRETE DESIGN

FINISH

11B.4 Beam DesignBeams are designed for flexure, shear and torsion. If required the effect of the axial force maybe taken into consideration. For all these forces, all active beam loadings are prescanned toidentify the critical load cases at different sections of the beams. The total number of sectionsconsidered is 13. All of these sections are scanned to determine the design force envelopes.

For design to be performed as per IS:13920 the width of the member shall not be less than 200mm(Clause 6.1.3). Also the member shall preferably have a width-to depth ratio of more than0.3 (Clause 6.1.2).

The factored axial stress on the member should not exceed 0.1fck (Clause 6.1.1) for all activeload cases. If it exceeds allowable axial stress no design will be performed.

11B.4.1 Design for Flexure

Design procedure is same as that for IS 456. However while designing following criteria aresatisfied 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 = 0.24√fck/fy

The maximum steel ratio on any face, at any section, is given by (Clause 6.2.2)

ρmax = 0.025

4. The positive steel ratio at a joint face must be at least equal to half the negative steel atthat face. (Clause 6.2.3)

5. The steel provided at each of the top and bottom face, at any section, shall at least beequal to one-fourth of the maximum negative moment steel provided at the face ofeither joint. (Clause 6.2.4)

11B.4.2 Design for Shear

The shear force to be resisted by vertical hoops is guided by the Clause 6.3.3 of IS 13920:1993revision. Elastic sagging and hogging moments of resistance of the beam section at ends areconsidered while calculating shear force. Plastic sagging and hogging moments of resistancecan also be considered for shear design if PLASTIC parameter is mentioned in the input file.(Refer Table 8A1.1)

Shear reinforcement is calculated to resist both shear forces and torsional moments.Procedure is same as that of IS 456.

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 shall not 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 456 consideration isprovided.

11B.4.3 Beam Design Output

The default design output of the beam contains flexural and shear reinforcement provided at5 equally spaced sections along the length of the beam. User has option to get a more detailoutput. All beam design outputs are given in IS units. An example of rectangular beamdesign output with the TRACK 2.0 is presented below:

B E A M N O. 1 D E S I G N R E S U L TS


LENGTH: 6400.0 mm SIZE: 300.0 mm X 400.0 mmCOVER: 25.0 mm

461 — STAAD.Pro


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 | 50.510.00 1

| 0.00 0.00 0.00 1 |1066.7 | 0.00 53.88 0.00 1 | 40.41

0.00 1| 0.00 0.00 0.00 1 |

1600.0 | 0.00 72.73 0.00 1 | 30.310.00 1

| 0.00 0.00 0.00 1 |2133.3 | 0.00 86.20 0.00 1 | 20.20

0.00 1| 0.00 0.00 0.00 1 |

2666.7 | 0.00 94.28 0.00 1 | 10.100.00 1

| 0.00 0.00 0.00 1 |3200.0 | 0.00 96.98 0.00 1 | 0.00

0.00 1| 0.00 0.00 0.00 1 |

3733.3 | 0.00 94.28 0.00 1 | -10.100.00 1

| 0.00 0.00 0.00 1 |4266.7 | 0.00 86.20 0.00 1 | -20.20

0.00 1| 0.00 0.00 0.00 1 |

4800.0 | 0.00 72.73 0.00 1 | -30.310.00 1

| 0.00 0.00 0.00 1 |5333.3 | 0.00 53.88 0.00 1 | -40.41

0.00 1| 0.00 0.00 0.00 1 |

5866.7 | 0.00 29.63 0.00 1 | -50.510.00 1

| 0.00 0.00 0.00 1 |6400.0 | 0.00 0.00 0.00 1 | -60.61

0.00 1| 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 OFIS-13920

NOTE :

MOMENT OF RESISTANCE IS CALCULATED BASED ON THE AREA OF STEELPROVIDED.

IF AREA OF STEEL PROVIDED IS MUCH HIGHER COMPARED TO AREA OFSTEEL

REQUIRED MOMENT OF RESISTANCE WILL INCREASE WHICH MAY INCREASEDESIGN

SHEAR 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 mm2133.3 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )|

8í @ 180 mm2666.7 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )|

8í @ 180 mm3200.0 | 0.00/ 402.12( 2-16í )| 894.99/1472.62( 3-25í )|

8í @ 180 mm3733.3 | 0.00/ 402.12( 2-16í )| 863.91/1472.62( 3-25í )|

8í @ 180 mm4266.7 | 0.00/ 402.12( 2-16í )| 773.83/1472.62( 3-25í )|

8í @ 180 mm4800.0 | 0.00/ 402.12( 2-16í )| 632.82/1472.62( 3-25í )|

8í @ 180 mm5333.3 | 0.00/ 402.12( 2-16í )| 450.84/1472.62( 3-25í )|

8í @ 180 mm5866.7 | 0.00/ 402.12( 2-16í )| 281.26/1472.62( 3-25í )|

8í @ 180 mm6400.0 | 0.00/ 402.12( 2-16í )| 0.00/ 981.75( 2-25í )|

8í @ 100 mm---------------------------------------------------------------

-------------

11B.5 Column DesignColumns are designed for axial forces and biaxial moments per IS 456:2000. Columns are alsodesigned for shear forces as per Clause 7.3.4. All major criteria for selecting longitudinal andtransverse reinforcement as stipulated by IS:456 have been taken care of in the column designof STAAD. However following clauses 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)

463— STAAD.Pro


l The minimum dimension of column member shall not be less than 200 mm. Forcolumns having unsupported length exceeding 4m, the shortest dimension of columnshall not be less than 300 mm. (Clause 7.1.2)

l The ratio of the shortest cross-sectional dimension to the perpendicular dimensionshall 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 the column,except where special confining reinforcement is provided. (Clause 7.3.3)

l Special confining reinforcement shall be provided over a length lo from each joint face,towards mid span, and on either side of any section, where flexural yielding may occur.The length lo shall not be less than a) larger lateral dimension of the member at thesection where yielding occurs, b) 1/6 of clear span of the member, and c) 450 mm.(Clause 7.4.1)

l The spacing of hoops used as special confining reinforcement shall not exceed ¼ ofminimum member dimension but need not be less than 75 mm nor more than 100mm. (Clause 7.4.6)

l The area of cross-section of hoops provided are checked against the provisions forminimum 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)

11B.5.1 Column Design Output

Default column design output (TRACK 0.0) contains the reinforcement provided by STAADand the capacity of the section. With the option TRACK 1.0, the output contains intermediateresults such as the design forces, effective length coefficients, additional moments etc. Aspecial output TRACK 9.0 is introduced to obtain the details of section capacity calculations.All design output is given in SI units. An example of a column design output (with optionTRACK 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


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 : -

-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 DESIGNRESULTS********************

11B.6 Bar CombinationInitially the program selects only one bar to calculate the number of bars required and area ofsteel provided at each section along the length of the beam. You may use theBAR COMBINATION command to specify two bar diameters to calculate a combination of eachbar to be provided at each section. The syntax for bar combination is given below.

START BAR COMBINATION



465— STAAD.Pro


ENDBAR COMBINATION

Note: The bar sizes should be specified in the order of increasing size (i.e., MD2 bardiameter should be greater than MD1 bar diameter).

The beam length is divided into three parts, two at its ends and one at span. Ld gives thedevelopment 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 |


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 |


Ast Reqd| 632.82 | 894.99 |632.82 |

Prov| 804.57 | 1384.43 |804.57 |

Ld (mm) | 752.2 | 1175.3 |752.2 |

----------------------------------------------------------------------------

===================================================================-=========

11B.7 Verification ExampleSample example showing calculation of design shear force as per Clause 6.3.3


Figure 11B.1 - Example problem

11B.7.1 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 to the main reinforcing bar = 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 fromgravity load on span =

Va = Vb = 1.2 * w * L / 2 = 15600N

Calculation of Moment Of Resistances Based On Area Of Steel Provided

Sagging Moment OfResistance 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 OfResistance of End AMicah =

0.87 * fy * Ast_Top_A * d *

( 1 - Ast_Top_A * fy / b * d * fck)

= 54003057.45 N

467— STAAD.Pro


Sagging Moment OfResistance 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 OfResistance 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 the beamplus the factored gravity load on the span.

Figure 11B.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 11B.3 - Sway to left

Vul,a = Va + 1.4 [ ( Mu,ah + Mu,bs ) / L ]=

53402.14022 N

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) = 41337.69104 N

11B.7.2 For Beam No. 3

Section width, b 300 mm


Section depth, D 450 mm

Characteristic Strength of Steel fy 415 N/sq. mm

Characteristic Strength of Concrete fck 20 N/sq. mm

Clear cover to the main reinforcing bar 25 mm

Bar Diameter 12 mm

Effective Depth, d = 450 mm - 25 mm - 12 mm/2 =

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 shearfrom gravityload on span =

Va = Vb = 1.2 * w * L / 2 = 11700N

Calculation of Moment Of Resistances Based On Area Of Steel Provided

SaggingMoment OfResistance ofEnd A Mu,as =

0.87 * fy * Ast_Bot_A * d *

( 1 - Ast_Bot_A * fy / b * d * fck)

= 48452983 N

469— STAAD.Pro


HoggingMoment OfResistance ofEnd A Mu,ah =

0.87 * fy * Ast_Top_A * d *

( 1 - Ast_Top_A * fy / b * d * fck)

= 32940364.5 N

SaggingMoment OfResistance ofEnd A Mu,bs =

0.87 * fy * Ast_Bot_B * d *

( 1 - Ast_Bot_B * fy / b * d * fck)

= 32940364.5 N

HoggingMoment OfResistance ofEnd 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 the beamplus the factored gravity load on the span.

Figure 11B.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

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


471 — STAAD.Pro

11C. Indian Codes - Steel Design per IS 800 - 1984STAAD.Pro is capable of performing steel design based on the Indian code IS 800 - 1984General construction in steel - Code of practice.

Design of members per IS 800 requires the STAAD Indian Design Codes SELECT Code Pack.

Note: Steel design per the limit state method in IS 800 is also available in the SteelDesign mode in the Graphical User Interface.

11C.1 Design OperationsSTAAD contains a broad set of facilities for designing structural members as individualcomponents of an analyzed structure. The member design facilities provide the user with theability to carry out a number of different design operations. These facilities may be usedselectively in accordance with the requirements of the design problem. The operations toperform a design are:

l Specify the members and the load cases to be considered in the design.



l Specify whether to perform member selection by optimization.

These operations may be repeated by the user any number of times depending upon the designrequirements. The entire ISI steel section table is supported. Section 11C.13 describes thespecification of steel sections.

11C.2 General CommentsThis section presents some general statements regarding the implementation of IndianStandard code of practice (IS:800-1984) for structural steel design in STAAD. The designphilosophy and procedural logistics for member selection and code checking are based uponthe principles of allowable stress design. Two major failure modes are recognized: failure byoverstressing, and failure by stability considerations. The flowing sections describe the salientfeatures of the allowable stresses being calculated and the stability criteria being used.Members are proportioned to resist the design loads without exceeding the allowable stressesand the most economic section is selected on the basis of least weight criteria. The codechecking part of the program checks stability and strength requirements and reports thecritical loading condition and the governing code criteria. It is generally assumed that theuser will take care of the detailing requirements like provision of stiffeners and check the localeffects such as flange buckling and web crippling.

11C.3 Allowable StressesThe member design and code checking in STAAD are based upon the allowable stress designmethod as per IS:800 (1984). It is a method for proportioning structural members using designloads and forces, allowable stresses, and design limitations for the appropriate material underservice conditions. It would not be possible to describe every aspect of IS:800 in this manual.


This section, however, will discuss the salient features of the allowable stresses specified byIS:800 and implemented in STAAD. Appropriate sections of IS:800 will be referenced duringthe discussion of various types of allowable stresses.

11C.3.1 Axial Stress

Tensile Stress

The allowable tensile stress, as calculated in STAAD as per IS:800 is described below.

The permissible stress in axial tension, σat in MPa on the net effective area of the sectionsshall not exceed

σat = 0.6·fyWhere:

fy = minimum yield stress of steel in Mpa

Compressive Stress

Allowable compressive stress on the gross section of axially loaded compression members shallnot exceed 0.6·fy nor the permissible stress σaccalculated based on the following equation (perClause: 5.1.1):

σac = 0.6( fcc · fy)/[( fcc)n + (fy)

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

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.

11C.3.2 Bending Stress

The allowable bending stress in a member subjected to bending is calculated based on thefollowing formula: (Clause: 6.2.1)

σbt or σbc = 0.66 fyWhere:

σbt = Bending stress in tension

σbc = Bending stress in compression

fy = Yield stress of steel, in MPa

473— STAAD.Pro

11C. Indian Codes - Steel Design per IS 800 - 1984

For an I-beam or channel with equal flanges bent about the axis of maximum strength (z-zaxis), the maximum bending compressive stress on the extreme fibre calculated on the effectivesection shall not exceed the values of maximum permissible bending compressive stress. Themaximum permissible bending compressive stress shall be obtained by the following formula:(Clause: 6.2.2)

= +

σ 0.66bc

f f

f f( )( )

cb y

cbn

y

n n1/

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:

=

+

f k X k Ycb

c

c1 22

1

Where:

= +X Y 1π

r D

1

20 y

2

in MPa

=Yr( )

26.5(10)

1 / y

5

2

k1 = a coefficient to allow for reduction in thickness or breadth of flangesbetween points of effective lateral restraint and depends on ψ, the ratio of thetotal area of both flanges at the point of least bending moment to thecorresponding area at the point of greatest bending moment between suchpoints of restraint.

k2 = a coefficient to allow for the inequality of flanges, and depends on ω,the ratio of the moment of inertia of the compression flange alone to that of thesum of the moment of the flanges each calculated about its own axis parallel tothe y-yaxis of the girder, at the point of maximum bending moment.

1 = effective length of compression flange

ry = radius of gyration of the section about its axis of minimumstrength (y-y axis)

T = mean thickness of the compression flange, is equal to the area ofhorizontal portion of flange divided by width.

D = overall depth of beam

c1 ,c2 = respectively the lesser and greater distances from the section neutralaxis to the extreme fibres.


11C.3.3 Shear Stress

Allowable shear stress calculations are based on Section 6.4 of IS:800. For shear on the web,the gross section taken into consideration consist of the product of the total depth and theweb thickness. For shear parallel to the flanges, the gross section is taken as 2/3 times thetotal flange area.

11C.3.4 Combined Stress

Members subjected to both axial and bending stresses are proportioned accordingly to section7 of IS:800. All members subject to bending and axial compression are required to satisfy theequation of Section 7.1.1.(a) for intermediate points, and equation of Section 7.1.1.(b) forsupport points.

For combined axial tension and bending the equation of Section 7.1.2. is required to besatisfied.

Cm coefficients are calculated according to the specifications of Section 7.1.3. informationregarding occurrence of sidesway can be provided through the use of parameters SSY and SSZ.In the absence of any user provided information, sidesway will be assumed.

11C.4 Design ParametersIn STAAD implementation of IS:800, the user is allowed complete control of the designprocess through the use of design parameters. Available design parameters to be used inconjunction with IS:800 are listed in Table 7B.1 of this section along with their default valuesand applicable restrictions. Users should note that when the TRACK parameter is set to 1.0and use in conjunction with this code, allowable bending stresses in compression (FCY &FCZ), tension (FTY & FTZ), and allowable shear stress (FV) will be printed out in MemberSelection and Code Check output in Mpa. When TRACK is set to 2.0, detailed design outputwill be provided.



CODE - Must be specified asINDIAN



Table 11C.1-Indian Steel Design IS 800:1984 Parameters

475— STAAD.Pro



BEAM 3.0 0.0 = design only for endmoments and those atlocations specified by theSECTION command.

1.0 = calculate sectionforces at twelfth pointsalong the beam, design ateach intermediate locationand report the criticallocation where ratio ismaximum.

CMY

CMZ

0.85 for sideswayandcalculated for nosidesway

Cm value in local y & zaxes

DFF None(Mandatory fordeflection check)

"Deflection Length" /Maxm. allowable localdeflection


Joint No. denoting startingpoint for calculation of"Deflection Length" (SeeNote 1)


Joint No. denoting endpoint for calculation of"Deflection Length" (SeeNote 1)

DMAX 100.0 cm. Maximum allowable depth.

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.

LY Member Length Length in local y-axis tocalculate slenderness ratio.



LZ Member Length Same as above except inlocal z-axis (major).

MAIN 180 (Comp. Memb.) Allowable Kl/r forslenderness calculations forcompression members.

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 allowable stresses.

SSY 0.0 0.0 = Sidesway in local y-axis.

1.0 = No sidesway

SSZ 0.0 Same as above except inlocal z-axis.

TMAIN 400 (TensionMemb)

Allowable Kl/r forslenderness calculations fortension members.

TRACK 0.0 0.0 = Suppress criticalmember stresses

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)

477— STAAD.Pro



UNF 1.0 Same as above provided asa fraction of actualmember length.

UNL Member Length Unsupported length forcalculating allowablebending stress.

11C.4.1 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 "DeflectionLength" will be equal to the length of the member. However, in some situations, the"Deflection Length" may be different. A straight line joining DJ1 and DJ2 is used as thereference line from which local deflections are measured.

For example, refer to the figure below where a beam has been modeled using four jointsand three members. The “Deflection Length” for all three members will be equal to thetotal length of the beam in this case. The parameters DJ1 and DJ2 should be used tomodel this situation. Thus, for all three members here, DJ1 should be 1 and DJ2 shouldbe 4.


PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

b. If DJ1 and DJ2 are not used, "Deflection Length" will default to the member length andlocal deflections will be measured from original member line.


c. The above parameters may be used in conjunction with other available parameters forsteel design.

11C.5 Stability RequirementsSlenderness ratios are calculated for all members and checked against the appropriatemaximum values. Section 3.7 of IS:800 summarizes the maximum slenderness ratios fordifferent types of members. In STAAD implementation of IS:800, appropriate maximumslenderness ratio can be provided for each member. If no maximum slenderness ratio isprovided, compression members will be checked against a maximum value of 180 and tensionmembers will be checked against a maximum value of 400.

11C.6 Truss MembersAs mentioned earlier, a truss member is capable of carrying only axial forces. So in design notime is wasted in calculating bending or shear stresses, thus reducing design timeconsiderably. Therefore, if there is any truss member in an analysis (like bracing or strut, etc.),it is wise to declare it as a truss member rather than as a regular frame member with bothends pinned.

11C.7 Deflection CheckThis facility allows the user to consider deflection as a criteria in the CODE CHECK and MEMBERSELECTION processes. The deflection check may be controlled using three parameters whichare described in Table 11C.1. Note that deflection is used in addition to other strength andstability related criteria. The local deflection calculation is based on the latest analysis results.

11C.8 Code CheckingThe purpose of code checking is to verify whether the specified section is capable of satisfyingapplicable design code requirements. The code checking is based on the IS:800 (1984)requirements. Forces and moments at specified sections of the members are utilized for thecode checking calculations. Sections may be specified using the BEAM parameter or theSECTION command. If no sections are specified, the code checking is based on forces andmoments at the member ends.

The code checking output labels the members as PASSed or FAILed. In addition, the criticalcondition (applicable IS:800 clause no.), governing load case, location (distance from thestart) and magnitudes of the governing forces and moments are also printed out.


11C.9 Member SelectionSTAAD is capable of performing design operations on specified members. Once an analysishas been performed, the program can select the most economical section, that is, the lightestsection, which satisfies the applicable code requirements. The section selected will be of thesame type (I-Section, Channel etc.) as originally specified by the user. Member selection maybe performed with all types of steel sections listed in Section 11C.12 and user provided tables.

479— STAAD.Pro


Selection of members, whose properties are originally provided from user specified table, willbe limited to sections in the user provided table. Member selection can not be performed onmembers whose cross sectional properties are specified as PRISMATIC.

The process of MEMBER SELECTION may be controlled using the parameters listed in Table11C.1. It may be noted that the parameters DMAX and DMIN may be used to specify memberdepth constraints for selection. If PROFILE parameter is provided, the search for the lightestsection is restricted to that profile. Up to three (3) profiles may be provided for any memberwith a section being selected from each one.


11C.10 Member Selection By OptimizationSteel section selection of the entire structure may be optimized. The optimization methodutilizes a state-of-the -art numerical technique which requires automatic multiple analysis.The user may start without a specifically designated section. However, the section profile type(BEAM, COLUMN, CHANNEL, ANGLE etc.) must be specified using the ASSIGN command(see Chapter 6). The optimization is based on member stiffness contributions andcorresponding force distributions. An optimum member size is determined through successiveanalysis/design iterations. This method requires substantial computer time and hence shouldbe used with caution.

Refer to Section 5.48.4 of the Technical Reference Manual for additional details.

11C.11 Tabulated Results of Steel DesignFor code checking or member selection, the program produces the result in a tabulatedfashion. The items in the output table are explained as follows:

MEMBERthe member number for which the design is performed

TABLEthe INDIAN steel section name which has been checked against the steel code orhas been selected.

RESULTprints whether the member has PASSED or FAILed. If the RESULT is FAIL, therewill be an asterisk (*) mark in front of the member number.

CRITICAL CONDthe section of the IS:800 code which governs the design.


LOADINGprovides the load case number which governs the design.


FX, MY, and MZprovide the axial force, moment in local y-axis and moment in local z-axisrespectively. Although STAAD does consider all the member forces and moments(except torsion) to perform design, only FX,MY and MZ are printed since they arethe ones which are of interest, in most cases.


Note: If the parameter TRACK is set to 1.0, the program will block out part of the tableand will print allowable bending stresses in compression (FCY & FCZ) and tension(FTY & FTZ), allowable axial stress in compression (FA), and allowable shear stress(FV). When the parameter TRACK is set to 2.0 for all members parameter codevalues are as shown in the following example.

STAAD.PRO CODE CHECKING - ( IS-800) v1.0

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

|--------------------------------------------------------------------------|| Y

PROPERTIES ||************* | INCM UNIT || * |=============================| ===|=== --

---------- ||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 | INNEWT MM||--------------- + --

-----------|

481 — STAAD.Pro


| KL/R-Y= 74.2 | FA= 150.0 || 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 01 ||

|

|******************************************************************-********||*

*||* DESIGN SUMMARY ( KN-METR)

*||* --------------

*||*

*|


|* RESULT/ CRITICAL COND/ RATIO/ LOADING/*|

| FX MY MZ LOCATION|

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

| PASS 7.1.2 BEND C 0.684 1|

| 7.39 T 0.0 -112.1 0.00|

|**|

|*****************************************************************-*********|

11C.12 Indian Steel TableThis is an important feature of the program since the program will read section properties ofa steel member directly from the latest ISI steel tables (as published in ISI-800). Theseproperties are stored in memory corresponding to the section designation (e.g., ISMB250,etc.). If called for, the properties are also used for member design. Since the shear areas arebuilt in to these tables, shear deformation is always considered for these members.

Almost all ISI steel tables are available for input. A complete listing of the sections availablein the built-in steel section library may be obtained using the tools of the graphical userinterface.

Following are the descriptions of all the types of sections available:

11C.12.1 Rolled Steel Beams (ISJB, ISLB, ISMB and ISHB)

All rolled steel beam sections are available the way they are designated in the ISI handbook(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 theend (e.g., ISHB400 A, etc.).

1 TO 5 TA ST ISHB400A

11C.12.2 Rolled Steel Channels (ISJC, ISLC and ISMC)

All these shapes are available as listed in ISI section handbook. Designation of the channelsare per the scheme used by ISI.

10 TO 20 BY 2 TA ST ISMC125

12 TA ST ISLC300

483— STAAD.Pro


11C.12.3 Double Channels

Back to back double channels, with or without spacing between them, are available. The letterD in front of the section name will specify a double channel (e.g., D ISJC125, D ISMC75, etc.).

21 22 24 TA D ISLC225

11C.12.4 Rolled Steel Angles

Both rolled steel equal angles and unequal angles are available for use in the STAADimplementation of ISI steel tables. The following example with explanations will be helpful inunderstanding the input procedure:

At present there is no standard way to define the local y and z axes for an angle section. Thestandard section has local axis system as illustrated in Fig.2.4 of this manual. The standardangle 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-V axisspecified in the steel tables. Many engineers are familiar with a convention used by some otherprograms in which the local y-axis is the minor axis. STAAD provides for this convention byaccepting the command:

54 55 56 TA RA ISA50X30X6

Hint: RA denotes reverse angle

11C.12.5 Double Angles

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

14 TO 20 TA LD ISA50X30X5 SP 1.5

23 27 TA SD ISA75X50X6


11C.12.6 Rolled Tees (ISHT, ISST, ISLT and ISJT)

All the rolled tee sections are available for input as they are specified in the ISI handbook.The following example illustrates the designated method.

1 2 5 8 TA ST ISNT100

67 68 TA ST ISST250

11C.12.7 Pipes (Circular Hollow Sections)

To designate circular hollow sections from ISI tables, use PIP followed by the numerical valueof diameter and thickness of the section in mm omitting the decimal section of the valueprovided for diameter. The following example will illustrate 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 inside diameters ofthe 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 of specification isused.

11C.12.8 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 and Thickness) andnot by any table designations.


is a tube that has a height of 8, a width of 6, and a wall thickness of 0.5.

485— STAAD.Pro


Note: Only code checking and no member selection is performed for TUBE sectionsspecified this way.

11C.12.9 Plate And Angle Girders (With Flange Plates)

All plate and angle grinders (with flange plates) are available as listed in ISI section handbook.The following example with explanations will be helpful in understanding the inputprocedure.

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 11C.2-Flange angle key

E. Flange plate width in mm.

F. Flange plate thickness in mm.

11C.12.10 Single Joist with Channels and Plates on theFlanges to be Used as Girders

All single joist with channel and plates on the flanges to be used as girders are available aslisted in ISI section handbook. The following example with explanations will be helpful inunderstanding the input procedure.


A. Joist Designation

IW450 = ISWB450

B. Top flange channel designation:

350 = ISMC350

C. Constant (always X).

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 is moreefficient.

11C.13 Column With Lacings And BattensFor columns with large loads it is desirable to build rolled sections at a distance and inter-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 by lacing or bybatten plates having riveted or welded connection.

Table 11C.3 gives the parameters that are required for Lacing or batten design. Theseparameters will have to be provided in unit NEW MMS along with parameters defined inTable 11C.1.


487— STAAD.Pro


ParameterName


CTYPE 1 Type of joining

1. implies single lacing withriveted connection

2. implies double lacing withriveted connection

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. Thisparameter is used when memberproperties are defined through userprovided table using GENERAL option.

DBL 20 mm Nominal diameter of rivet

DCFR 0.0 Used when member properties aredefined through user provided tableusing 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

Table 11C.3-Parameters used in Indian Lacing or Batten steel memberdesign.


ParameterName


SPA 0.0 mm Spacing between double channels.This parameter is used when memberproperties are defined through userprovided table using GENERAL option.

THETA 50 degree Angle of inclination of lacing bars. Itshould lie between 40 degree and 70degree.

WMIN 6 mm Minimum thickness of weld

WSTR 108 N/mm2 Allowable welding stress

489— STAAD.Pro


11D. Indian Codes - Steel Design per IS 802STAAD.Pro is capable of performing steel design based on the Indian code IS 802 1995 Use ofStructural Steel in Overhead Transmission Line Towers - Code of Practice.


11D.1 General CommentsThis section presents some general statements regarding the implementation of IndianStandard code of practice (IS:802-1995 – Part 1) for structural steel design for overheadtransmission line towers in STAAD. The design philosophy and procedural logistics formember selection and code checking are based upon the principles of allowable stress design.Two major failure modes are recognized: failure by overstressing, and failure by stabilityconsiderations. The flowing sections describe the salient features of the allowable stresses beingcalculated and the stability criteria being used. Members are proportioned to resist the designloads without exceeding the allowable stresses and the most economic section is selected onthe basis of least weight criteria. The code checking part of the program checks stability andstrength requirements and reports the critical loading condition and the governing codecriteria.

11D.2 Allowable StressesThe member design and code checking in STAAD are based upon the allowable stress designmethod as per IS:802 (1995). It is a method for proportioning structural members using designloads and forces, allowable stresses, and design limitations for the appropriate material underservice conditions.

This section discusses the salient features of the allowable stresses specified by IS:802 andimplemented in STAAD.

11D.2.1 Axial Stress

Tensile Stress

The allowable tensile stress, as calculated in STAAD as per IS:802 is described below.

The estimated tensile stresses on the net effective sectional area in various members,multiplied by the appropriate factor of safety shall not exceed minimum guaranteed yieldstress of the material.

Thus, the permissible stress in axial tension, σat in MPa on the net effective area of the sectionsshall not exceed

σat = FyWhere:

Fy = minimum yield stress of steel in Mpa


Compressive Stress

The estimated compressive stresses in various members multiplied by the appropriate factor ofsafety shall not exceed the value given by the formulae described 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 = Fy1 - 0.5[(KL/r)/Cc]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 Fy the value Fcr given by:

Fcr = Fy[1.677 - 0.677·(b/t)/(b/t)lim]

III. Condition: when (b/t) > 378/√FyThe equations in condition 1 shall be used, substituting for Fy the value Fcr given 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

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 of themember,

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 not exceed 25.

11D.3 Stability RequirementsSlenderness ratios are calculated for all members and checked against the appropriatemaximum values. Following are the default values used in STAAD:

491 — STAAD.Pro

11D. Indian Codes - Steel Design per IS 802

11D.3.1 Compression Member

Type of Member SlendernessLimit

Leg Members, ground wire peakmember and lower members of crossarms in compression

120

Other members carrying computedstress

200

Redundant members and thosecarrying nominal stresses

250

Table 11D.1-Slenderness ratio limits of compressionmembers

Slenderness ratios of compression members are determined as follows:

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 both ends ofthe unsupported panel with values of L/r up to andincluding 120

L/r

3 Member with concentric loading at one end andnormal eccentricities at the other end of theunsupported panel for value of L/r up to andincluding 120

30 + 0.75L/r

4 Members with normal framing eccentricities atboth ends of the unsupported panel for values ofL/r up to and including 120

60 + 0.5L/r

5 Member unrestrained against rotation at both endsof the unsupported panel for value of L/r from 120to 200

L/r

6 Members partially restrained against rotation atone end of the unsupported panel for values of L/rover 120 and up to and including 225

28.6 +0.762L/r

Table 11D.2-Compression slenderness ratio calculation depending on ELAparameter


ELAValue

Type of Member Calculationof KL/r

7 Members partially restrained against rotation atboth ends of the unsupported panel for values ofL/r over 120 and up to and including 250

46.2 +0.615L/r

If the value for ELA is given in the input for any particular member is such that condition forL/r ratio to fall within the specified range is not satisfied, STAAD goes on by the usual way offinding slenderness ratio using KL/r formula.

11D.3.2 Tension Members

Slenderness ratio KL/r of a member carrying axial tension only, shall not exceed 400.

11D.4 Minimum Thickness RequirementAs per Clause7.1 of IS: 802-1995 minimum thickness of different tower members shall be asfollows:

Members Minimum Thickness (mm)

Galvanized Painted

Leg Members, ground wire peak member and lowermembers of cross arms in compression

5 6

Other members 4 5

11D.5 Code CheckingThe purpose of code checking is to verify whether the specified section is capable of satisfyingapplicable design code requirements. The code checking is based on the IS:802 (1995)requirements. Axial forces at two ends of the members are utilized for the code checkingcalculations.

The code checking output labels the members as PASSed or FAILed. In addition, the criticalcondition, governing load case, location (distance from the start) and magnitudes of thegoverning forces are also printed out. Using TRACK 9 option calculation steps are also printed.


11D.5.1 Design Steps

The following are the steps used by the program in member design:

1. Thickness of the member (maximum of web and flange thicknesses) is checked againstminimum allowable thickness, depending upon whether the member is painted orgalvanized.

493— STAAD.Pro


2. If the minimum thickness criterion is fulfilled, the program determines whether themember is under compression or tension for the load case under consideration.Depending upon whether the member is under tension or compression the slendernessratio of the member is calculated. This calculated ratio is checked against allowableslenderness ratio.

3. If the slenderness criterion is fulfilled check against allowable stress is performed.Allowable axial and tensile stresses are calculated. If the member is under tension andthere is no user defined net section factor (NSF), the net section factor is calculated bythe program itself (See "Calculation of Net Section Factor" on page 500). Actual axialstress in the member is calculated. The ratio for actual stress to allowable stress, if lessthan 1.0 or user defined value, the member has passed the check.

4. Number of bolts required for the critical load case is calculated.

11D.6 Member SelectionSTAAD is capable of performing design operations on specified members. Once an analysis hasbeen performed, the program can select the most economical section, that is, the lightestsection, which satisfies the applicable code requirements. The section selected will be of thesame type (either angle or channel) as originally specified by the user. Member selection maybe performed with all angle or channel sections and user provided tables. Selection ofmembers, whose properties 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 listed in Table9C.3. It may be noted that the parameters DMAX and DMIN may be used to specify memberdepth constraints for selection. If PROFILE parameter is provided, the search for the lightestsection is restricted to that profile. Up to three (3) profiles may be provided for any memberwith a section being selected from each one.


11D.7 Member Selection by OptimizationSteel section selection of the entire structure may be optimized. The optimization methodutilizes a state-of-the -art numerical technique which requires automatic multiple analysis.The optimization is based on member stiffness contributions and corresponding forcedistributions.

An optimum member size is determined through successive analysis/design iterations. Thismethod requires substantial computer time and hence should be used with caution.

Refer to Section 5.48.4 of the Technical Reference Manual for additional details.

11D.8 Tabulated Results of Steel DesignAn example of a TRACK 2.0 output for a compression member is shown here:

STAAD.PRO CODE CHECKING - ( IS-802)


v1.0

********************************************|---------------------------------------------------------------

-----------|| Y

PROPERTIES ||************* | INCM 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 INNEWT MM||--------------- ------------- --

-----------|| 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

|

495— STAAD.Pro


||

|******************************************************************-********||*


*||* --------------

*||*

*||* 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----------------------

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


11D.9 Design Parameters


ParameterName


CNSF 0.0 This parameter indicates whether userhas defined the net section factor orthe program will calculate it.

0. Use specified NSF value

1. Net section factor will becalculated.

Table 11D.3-Indian Steel Design IS 802 Parameters

497— STAAD.Pro


ParameterName


DANGLE 0.0 This parameter indicates how the pairof angles are connected to each other.This is required to find whether theangle is in single or double shear andthe net section factor.

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 one legof each angle to the same sideof 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 ofend conditions is to be used. ReferSection 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, this isminor axis.

KZ 1.0 K value in local z-axis. Usually, this ismajor axis.


ParameterName


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 allowable Kl/rfor slenderness calculations formembers.

1. Leg, Ground wire peak andlower members of cross arms incompression (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 10.0 indicatesuser defined allowable KL/r ratio. Forthis case KY and KZ values are mustto find actual KL/r ratio of themember.

NSF 1.0 Net section factor for tensionmembers

499— STAAD.Pro


ParameterName


NHL 0.0 mm Deduction for holes.

Default value is one bolt width plus1.5 mm. If the area of holes cut by anystraight, diagonal or zigzag line acrossthe member is different from thedefault value, this parameter is to bedefined.

TRACK 0.0 Level of output detail:

0. Suppress critical memberstresses

1. Print all critical memberstresses

2. Print expanded output.

9. Print design calculations alongwith expanded output (notavailable in GUI input).

11D.10 Calculation of Net Section FactorThe procedure for calculating the net section factor for an angle section is as follows:

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 + A2 · K1

Where:

A1 = net cross-sectional area of the connected leg

A2 = gross cross-sectional area of the unconnected leg

K1 = 3·A1/(3·A1 + A2)

The area of a leg of an angle = Thickness of angle x (length of leg – 0.5x thicknessof leg)

b. Pair of angles placed back-to-back connected by only one leg of each angle to thesame side of a gusset plate

Anet = A1 + A2 · K1


Where:

A1 = net cross-sectional area of the connected leg

A2 = gross cross-sectional area of the unconnected leg

K1 = 5·A1/(5·A1 + A2)

The area of a leg of an angle = Thickness of angle x (length of leg – 0.5xthickness of leg)

c. Double angles placed back-to-back and connected to each side of a gusset plate

Anet = gross area minus the deduction for holes

11D.11 Example Problem No. 28A transmission line tower is subjected to different loading conditions. Design some membersas per IS-802 and show detailed calculation steps for the critical loading condition.

501 — STAAD.Pro


11D.11.1 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

Thickness of the gusset plate = 8 mm

Net Section Factor is to be calculated.

11D.11.2 STAAD Input File

This input file is included with the program as C:\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 92.4;

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 24 1.4;

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 1.424 -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; 484.2 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; 610 35 0;

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;

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; 2620 10;


27 12 2; 28 11 3; 29 1 13; 30 13 4; 31 3 14; 32 14 5; 33 15 4; 3415 6;

35 16 5; 36 16 7; 37 17 6; 38 17 8; 39 18 7; 40 18 9; 41 19 8; 4219 10;

43 20 9; 44 20 2; 45 12 10; 46 21 23; 47 23 24; 48 24 25; 49 2526; 50 26 27;

51 27 28; 52 28 29; 53 29 30; 54 30 22; 55 3 23; 56 4 24; 57 525; 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 3 24;

67 23 4; 68 4 25; 69 5 24; 70 5 26; 71 6 25; 72 6 27; 73 7 26; 747 28;

75 8 27; 76 8 29; 77 9 28; 78 9 30; 79 10 29; 80 10 22; 81 2 30;82 31 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;

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;

503— STAAD.Pro


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;


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 TO 144155 156 -

159 160 223 224 229 230 235 TO 250 TA ST ISA150X150X10

27 63 99 126 149 TO 154 157 158 161 TO 214 219 TO 222 225 TO 228231 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

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

PERFORM ANALYSIS

UNIT NEW MMS

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 CODE MEMB 1 28

FINISH

11D.11.3 Output

A portion of the output for the TRACK 9.0 member code check follows:

505— STAAD.Pro


STAAD.PRO CODE CHECKING - ( IS-802)v1.0

********************************************|----------------------------------------------------------------

----------|| Y

PROPERTIES ||************* | IN

CM UNIT || * |=============================| ==||== ---

--------- ||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 INNEWT 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

|| LEG = 1.0

|| ELA = 4.0

|| NSF = 1.0

|


||

|*****************************************************************-*********||*


*||* --------------

*||*



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

|| PASS COMPRESSION 0.744 1

|| 1742.26 C 0.0 0.0 0.00

||*

*|

|*****************************************************************-*********||

||---------------------------------------------------------------

-----------|STAAD TRUSS --

PAGE NO. 5DETAILS OF CALCULATION----------------------


TYPE : PAINTED



RESULT : PASS



EQN. USED TO FIND KL/r : 60.0 + 0.5*L/r



RESULT : PASS


CRITICAL CONDITION : COMPRESSION

507— STAAD.Pro


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


LOAD NO. : 1


ACTUAL AXIAL COMP. STRESS :1742259.75 / 12000.0 : 145.19 MPA

RESULT : PASSSTAAD TRUSS --

PAGE NO. 6

BOLTING-------

BOLT DIA : 16 MM



BOLT CAP : 55.81 KN

NO. OF BOLTS REQD. : 32STAAD TRUSS --

PAGE NO. 7STAAD.PRO CODE CHECKING - ( IS-802)

v1.0********************************************

|--------------------------------------------------------------------------|| Y

PROPERTIES ||************* | IN

CM UNIT || * |=============================| ==| |== ---

--------- ||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 || * |<---LENGTH (ME= 6.53 --->| RY

= 5.9 ||************* RZ

= 3.0 |


||

||

|PARAMETER BOLTINGSTRESSES ||IN NEWT MM INNEWT 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

||

|

|*****************************************************************-*********||*


*||* --------------

*||*



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

|| PASS TENSION 0.194 3

|| 112.86 T 0.0 0.0 6.53

||*

*|

509— STAAD.Pro


|******************************************************************-********||

||----------------------------------------------------------------

----------|STAAD TRUSS --

PAGE NO. 8DETAILS OF CALCULATION----------------------


TYPE : PAINTED



RESULT : PASS



EQN. USED TO FIND KL/r : K*L/r



RESULT : PASS


CRITICAL CONDITION : TENSION

ALLOWABLE AXIAL TENSILE STRESS : 249.94 MPA


LOAD NO. : 3


ACTUAL AXIAL TENSILE STRESS : 112855.91 / ( 2920.0*0.797 ) :48.51 MPA

RESULT : PASS

BOLTING-------

BOLT DIA : 16 MM



BOLT CAP : 43.83 KN

NO. OF BOLTS REQD. : 3STAAD TRUSS --

PAGE NO. 9



511 — STAAD.Pro

11E. Indian Codes - Design per Indian Cold Formed SteelCode

STAAD.Pro is capable of performing steel design based on the Indian code IS 801 1975 Code ofpractice for use of cold formed light gauge steel structural members in general buildingconstruction, including revisions dated May, 1988. The program allows design of single (non-composite) members in tension, compression, bending, shear, as well as their combinations.Cold work of forming strengthening effects has been included as an option.


11E.1 Cross-Sectional PropertiesThe user specifies the geometry of the cross-section by selecting one of the section shapedesignations from the Gross Section Property Tables from IS:811-1987 (Specification for coldformed light gauge structural steel sections).


l Channel with Lips


l Angle without Lips

l Z with Lips

l Hat

Shape selection may be done using the member property pages of the graphical user interface(GUI) or by specifying the section designation symbol in the input file.


11E.2 Design ProcedureThe program calculates effective section properties in accordance with Clause 5.2.1.1. Cross-sectional properties and overall slenderness of members are checked for compliance with

l Clause 6.6.3, Maximum Effective Slenderness Ratio for members in Compression

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 the Standard asfollows:

11E.2.1 Members in tension

Resistance is calculated in accordance with Clauses 6.1


11E.2.2 Members in bending and shear


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.

11E.2.3 Members in compression


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 of open crosssection or intermittently fastened singly-symmetrical components of built-up shapeshaving Q = 1.0 which may be subject to torsional-flexural buckling,

l Clause 6.6.1.3 Singly-symmetric sections and nonsymmetrical shapes or intermittentlyfastened singly-symmetrical components of built-up shapes having Q < 1.0 which maybe subject to torsional-flexural buckling,

l Clause 6.8 Cylindrical Tubular Sections.

11E.2.4 Members in compression and bending


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 torsional or torsional-flexural buckling

l Clause 6.7.2. Singly-symmetric shapes or Intermittently fastened singly-symmetriccomponents of built-up shapes having Q=1.0 which may be subjected to torsional-flexural buckling

l Clause 6.7.3. Singly-symmetric shapes or Intermittently fastened singly-symmetriccomponents of built-up shapes having Q<1.0 which may be subjected to torsional-flexural buckling.

11E.3 Code Checking and Member SelectionThe following two design modes are available:

11E.3.1 Code Checking

The program compares the resistance of members with the applied load effects, in accordancewith IS:801-1975. Code checking is carried out for locations specified by the user via theSECTION command or the BEAM parameter. The results are presented in a form of a

513— STAAD.Pro

11E. Indian Codes - Design per Indian Cold Formed Steel Code

PASS/FAIL identifier and a RATIO of load effect to resistance for each member checked. Theuser may choose the degree of detail in the output data by setting the TRACK parameter.


11E.3.2 Member Selection

The user may request that the program search the cold formed steel shapes database (ISstandard sections) for alternative members that pass the code check and meet the least weightcriterion. In addition, a minimum and/or maximum acceptable depth of the member may bespecified. The program will then evaluate all database sections of the type initially specified(i.e., channel, angle, etc.) and, if a suitable replacement is found, presents design results forthat section. If no section satisfying the depth restrictions or lighter than the initial one canbe found, the program leaves the member unchanged, regardless of whether it passes the codecheck or not.


11E.4 Design ParametersInput for the coefficients of uniform bending must be specified.

The following table contains the input parameters for specifying values of design variables andselection of design options.


ParameterName


CODE - Must be specified as IS801



Table 11E.1-Indian cold formed steel design parameters


ParameterName


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. ForTRUSS members only start andend locations are designed.

1. the adequacy of the member isdetermined by checking a totalof 13 equally spaced locationsalong the length of themember.

CMY 0.85 Coefficient of equivalent uniformbending Ωy. See IS:801-1975, 6.7. Usedfor Combined axial load and bendingdesign. Values range from 0.4 to 1.0.

CMZ 1.0 Coefficient of equivalent uniformbending Ωz. See IS:801-1975, 6.7. Usedfor Combined axial load and bendingdesign. Values range from 0.4 to 1.0.

CWY 0.85 Specifies whether the cold work offorming strengthening effect should beincluded in resistance computation.See IS:801-1975, 6.1.1

0. effect should not be included

1. effect should be included

FLX 1 Specifies whether torsional-flexuralbuckling restraint is provided or is notnecessary for the member. See IS:801-1975, 6.6.1

0. Section not subject to torsionalflexural buckling

1. Section subject to torsionalflexural buckling

515— STAAD.Pro


ParameterName


FU 450 MPa

(4588.72

kg/cm2)

Ultimate tensile strength of steel incurrent units.

FYLD 353.04 MPa

(3600.0

kg/cm2)

Yield strength of steel in current units.

KX 1.0 Effective length factor for torsionalbuckling. It is a fraction and is unit-less. Values can range from 0.01 (for acolumn completely prevented frombuckling) to any user specified largevalue. It is used to compute the KL/Rratio for twisting for determining thecapacity in axial compression.

KY 1.0 Effective length factor for overallbuckling about the local Y-axis. It is afraction and is unit-less. Values canrange from 0.01 (for a columncompletely prevented from buckling)to any user specified large value. It isused to compute the KL/R ratio fordetermining the capacity in axialcompression.

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 from buckling)to any user specified large value. It isused to compute the KL/R ratio fordetermining the capacity in axialcompression.


ParameterName


LX Memberlength

Unbraced length for twisting. It isinput in the current units of length.Values can range from 0.01 (for amember completely prevented fromtorsional buckling) to any userspecified large value. It is used tocompute the KL/R ratio for twistingfor determining the capacity in axialcompression.

LY Memberlength

Effective length for overall buckling inthe local Y-axis. It is input in thecurrent units of length. Values canrange from 0.01 (for a membercompletely prevented from buckling)to any user specified large value. It isused to compute the KL/R ratio fordetermining the capacity in axialcompression.

LZ Memberlength

Effective length for overall buckling inthe local Z-axis. It is input in thecurrent units of length. Values canrange from 0.01 (for a membercompletely prevented from buckling)to any user specified large value. It isused to compute the KL/R ratio fordetermining the capacity in axialcompression.

MAIN 0 0 – Check slenderness ratio

0 – Do not check slenderness ratio


DMAX 2540.0

cm.

Maximum allowable depth, in thecurrent units.

RATIO 1.0 Permissible ratio of actual to allowablestresses

STIFF MemberLength

Spacing of shear stiffeners for stiffenedflat webs, in current units.

517— STAAD.Pro


ParameterName



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 stiffened tosatisfy the requirements of IS:801-1975,5.2.4.

0. Do not comply with 5.2.4

1. Comply with 5.2.4


519— STAAD.Pro

11F. Indian Codes - Steel Design per IS 800:2007STAAD.Pro is capable of performing steel design based on the Indian code IS 800 - 2007General construction in steel - Code of practice.


11F.1 General CommentsFor steel design, STAAD compares the actual design forces with the capacities as defined bythe Indian Standard Code. The IS 800: 2007 Code is used as the basis of this design.

A brief description of some of the major capacities is described herein.

The following commands should be used to initiate design per Limit State Method of thiscode:

PARAMETER n

CODE IS800 LSD

The following commands should be used to initiate design per Working Stress Method of thiscode:

PARAMETER n

CODE IS800 WSD

Note: STAAD.Pro V8i (SELECTseries 3) (release 20.07.08) or higher are required for designper WSD.

Where:

n = optional integer (i.e., - 1, 2) which signifies the numerical order of parametercommand block (if multiple blocks are specified).

11F.2 Design ProcessThe design process follows the following design checks.

1. Slenderness

2. Section Classification

3. Tension

4. Compression

5. Shear

6. Bending

7. Combined Interaction Check

All of the design check criteria are described in the following sections.


When a design is performed, the output file reports the maximum utilization ratio from allthe above mentioned checks.

11F.2.1 Slenderness

As per Section 3.8 Table 3, the slenderness ratio (KL/r) of compression members shall notexceed 180, and the slenderness ratio (L/r) of tension members shall not exceed 400.

You can edit the default values through MAIN and TMAIN parameters, as defined in Table11F.1.

11F.2.2 Section Classification

The IS 800: 2007 specification allows inelastic deformation of section elements. Thus localbuckling becomes an important criterion.

Steel sections are classified as Plastic, Compact, Semi-Compact, or Slender element sectionsdepending upon their local buckling characteristics.

This classification is a function of the geometric properties of the section as well as nature ofthe load applied to the member. The design procedures are different depending on thesection class.

STAAD is capable of determining the section classification for the standard shapes and designthe section for the critical load case accordingly. The Section Classification is done as persection 3.7 of IS 800:2007 and Table B2, for Outstanding and Internal Elements of a section.

For the criteria for being included in those classes, refer to section 3.7.2-(a) – (d) of the code.

Slender Sections

STAAD.Pro is capable of designing I-Sections with slender webs for IS 800:2007.

Note: This feature requires STAAD.Pro V8i (SELECTseries 3) (release 20.07.08) or higher.

The IS:800-2007 code does not provide any clear guidelines about what method should beadopted for the design of slender section. The "Flange Only" methodology is used where it isassumed that flexure is taken by the flanges alone and the web will resist shear with adequateshear buckling resistance. This method requires that the flanges be non-slender elements (i.e.,on the web is a slender element) to qualify for a valid section for design. If any of the flangeelements become slender, the design will not be performed and a warning message isdisplayed in the output.

11F.2.3 Tension

Limit State Method

The criteria governing the capacity of Tension members are based on:

521 — STAAD.Pro

11F. Indian Codes - Steel Design per IS 800:2007

l Design Strength due to Yielding in Gross Section

l Design Strength due to Rupture of Critical Section

l Design Strength due to Block Shear

STAAD calculates the tension capacity of a given member based on these three limit states.

The limit state of yielding in the gross section is intended to prevent excessive elongation ofthe member, and the corresponding check is done as per section 6.2 of the code.

The Design strength, involving rupture at the section with the net effective area, is evaluatedas per section 6.3 of the code. Here, the number of bolts in the connection may be specifiedthrough the use of the design parameter ALPHA.

The Design strength, involving block shear at an end connection, is evaluated as per section6.4 of the code. This criteria is made optional by the parameter DBS. If the value of DBS isspecified as 1, additional design parameters AVG, AVN, ATG, and ATN must be supplied to theprogram for that member.

The Net Section Area may be specified through the use of the parameter NSF.

Working Stress Method

The criteria governing the allowable stress from tension in members are based on Section 11.2.1of the code:

l Yielding of Gross Section - to prevent excessive elongation of the member due tomaterial yielding.

l Rupture of Net Section - to prevent rupture of the net effective section area. Thenumber of bolts in the connection may be specified through the use of the designparameter ALPHA. The code parameter, γM1, is taken as 1.25 per Table 5, Clause 5.4.1 of thecode.

l Block Shear — to prevent block shearing at the end connection. This check is madeoption through use of the DBS parameter. Additional design parameters AVG, AVN, ATG,and ATN must be supplied to the program for any member which is to be checked forblock shear. The code parameters,, γM0 and γM1, are taken as 1.10 and 1.25, respectively,per Table 5, Clause 5.4.1 of the code.

Note: Block shear is not checked by default.

These criteria are dependant on the steel material yield stress parameter, FYLD, and ultimatetensile strength parameter, FU.

11F.2.4 Compression

The design capacity of the section against Compressive Force, the guiding phenomenon is theflexural buckling.


Limit State Method

The buckling strength of the member is affected by residual stress, initial bow and accidentaleccentricities of load.

To account for all these factors, the strength of the members subjected to axial compression isdefined by buckling class a, b, c or d as per clause 7.1.2.2 and Table 7 of IS 800:2007.

Imperfection factor, obtained from buckling class, and Euler’s Buckling Stress ultimatelygovern compressive force capacity of the section as per clause 7.1.2 of IS 800:2007.


The actual compressive stress is given by:

fc = FX/Ae

Where:

Ae = The effective section area as per Clause 7.3.2 of the code. This is equal tothe gross cross sectional area, AX, for any non-slender (plastic, compact, orsemi-compact) section class. In the case of slender sections, this is limited tovalue of Ae as described below.

The permissive compressive stress is calculated by first determining the Buckling Class of thesection per Table 10 of the code and αYY & αZZ based on Table 7.

Fac = 0.6·FcdWhere:

Fcd = the minimum of the values of Fcd calculated for the local Y and Z axis.

Fcd = (FYLD/γmo)/ [φ + (φ2 + λ2]

λ = the non-dimensional slenderness factor is evaluated for each local Y and Zaxis.

λ = (FYLD/Fcc)1/2

φ = 0.5[ 1 + a(λ - 0.2) + λ2]

Fcc = the Euler Buckling Stress.

Fcc = π2·E/(Kl/r)2

K = the effective length factor for bending about either the local Y or Z axis, asprovided in the KY and KZ parameters, respectively.

r = radius of gyration about the local Y or Z axis for the section.

FYLD = The yield strength of steel specified in the FYLD parameter.

523— STAAD.Pro


Slender Sections

For member with slender section under axial compression, design compressive strength shouldbe calculated on area ignoring depth thickness ratio of web in excess of the class 3 (semi-compact) limit.

Refer to clause 7.3.2 and Table 2 of IS 800:2007, (corresponding to “Internal Element ofCompression Flange”)

Ae= Ag - (d/tw - 42ε) · tw2

Where:

Ae = Effective area of section.

Ag = Gross area of section.

d = Depth of web.

tw = thickness of web.

11F.2.5 Shear

The design capacities of the section against Shear Force in major- and minor-axis directionsare evaluated as per section 8.4 of the code, taking care of the following phenomena:

l Nominal Plastic Shear Resistance

l Resistance to Shear Buckling

Shear area of the sections are calculated as per sec. 8.4.1.1.

Nominal plastic shear resistance is calculated as per sec. 8.4.1.

Among shear buckling design methods, Simple post-critical method is adopted as per sec.8.4.2.2(a).

Working Stress Design

The actual shear stress is determined about the major and minor axes, respectively:

τbY = FY / AY

τbZ = FZ / AZ

The permissible shear stress is determined as:

a. When subjected to pure shear:

τab = 0.40 · FYLD

b. When subjected to shear buckling:

τab = 0.70 · Vn · Av

Where:


Vn = Nominal Shear Strength as per Clause 8.4.2.2.(a)

Vn = Vcr = τb · Av

Av = AY or AZ, whichever is appropriate, with reference to Clause 8.4.1.1.

Shear buckling must be checked when (d/ tw) > 67 · ϵw for webs withoutstiffener or (d/tw) > 67 · ϵw · √(Kv/5.35) for webs with stiffeners.

d = Clear Depth of Web between Flanges.

tw = Thickness of Web.

FYLD = Yield Strength of Web.

w = √ ( 250 / FYLD )

Kv = Shear Buckling Coefficient:

= 5.35, when transverse stiffeners are provided only atsupports.

= 4.0 + 5.35 / (c/d)2 for (c/d) < 1.0

= 5.35 + 4.0 / (c/d)2 for (c/d) ≥ 1.0

c = Spacing of Transverse Stiffeners

μ = Poisson’s Ratio

τb = Shear Stress corresponding to Web-buckling:

= FYLD / √3, when, λw ≤ 0.8

= ( 1 – 0.8 · (λw - 0.8) ) · (FYLD / √3) when, 0.8 < λw < 1.2

= FYLD / (√3 · λw2 ) when, λw ≥ 1.2

τcr,e = The Elastic Critical Shear Stress of the Web

τcr,e = (Kv · π2 · E) / (12 · (1 – μ2 ) · (d/tw)

2 )

λw = Non-dimensional Web Slenderness Ratio for Shear Buckling Stress.

λw = [FYLD / (√3 · τcr,e)]1/2

Slender Sections

Slender sections should be verified against shear buckling resistance if d/tw > 67 · ε for webwithout stiffeners or if it exceeds 67 · ε · √(Kv⁄5.35) for a web with stiffeners.

Design methods for resistance to shear buckling are described in clause 8.4.2.2 of IS:800-2007code.

Vn = Vcr

Where:

525— STAAD.Pro


Vcr = shear force corresponding to web buckling

= Av · τbτb = shear stress corresponding to web buckling, determined as follows:

i. When λw ≤ 0.8

τb= fyw⁄√3

ii. When 0.8 < λw < 1.2

τb= [1 - 0.8(λw - 0.8) ](fyw⁄√3)

iii. When λw ≥ 1.2

τb= fyw⁄((√3 λw2 ) )

λw = non-dimensional web slenderness ratio or shear buckling stress, given by:

λw= [ fyw⁄(√3 τcr,e )]1/2

τcr,e = elastic critical shear stress of the web

= (kv·π2·E)/[12·(1 - μ2 ) (d⁄tw)

2]

μ = Poisson’s ratio and

Kv =

l 5.35 when transverse stiffeners are provided only at supports

l 4.0 + 5.35/(c/d)2 for c/d < 1.0

l 5.35 + 4.0/(c/d)2 for c/d ≥ 1.0

c = spacing of transverse stiffeners

d = depth of the web

11F.2.6 Bending

The design bending moment capacity of a section is primarily dependent on whether themember is laterally supported or unsupported.

You can control the lateral support condition of the member by the use of LAT parameter.

If the member is laterally supported, then the design strength is calculated as per theprovisions of the section 8.2.1 of IS 800:2007, based on the following factors:

l Whether section with webs susceptible to shear buckling before yielding

l Shear Force to Design Shear Strength Ratio

l Section Classification

If the member is laterally unsupported, then the design strength is calculated as per theprovisions of the section 8.2.2 of IS 800:2007, based on the following factors:


l Lateral Torsional Buckling

l Section Classification

Working Stress Design

Actual bending stress values are given by, about major (Z) and minor (Y) axes, respectively:

fbcz = Mz/Zeczfbtz = Mz/Zetzfbcy = My/Zecyfbty = My/Zety

The permissible bending stress is given as follows:

a. For laterally supported beams:

Fabc = Fabt = 0.66·FYLD for Plastic or Compact sections

Fabc = Fabt = 0.60·FYLD for Semi-compact sections

b. For laterally unsupported beams:

i. About the major axis:

fabcz = 0.60·Md/Zeczfabtz = 0.60·Md/Zetz

Where:

Md = Design Bending Strength as per Clause 8.2.2

Md = βb · Zpz · fbdfbd = χLT · FYLD / γmoZez = Elastic Section Modulus of the Section.

Zpz = Plastic Section Modulus of the Section.

αLT = 0.21 for Rolled Steel Section and 0.49 for Welded SteelSection

βb = 1.0 for Plastic and Compact Section or Zez/Zpz for Semi-Compact Section.

λLT = Non-dimensional slenderness ratio

λLT = (βb · Zpz · FYLD / Mcr)1/2 ≤ (1.2 · Zez · FYLD / Mcr )

1/2

ϕLT = 0.5 · ( 1 + αLT · ( λLT – 0.2 ) + λLT2)

χLT = The Bending Stress Reduction Factor to account for Lateral

527— STAAD.Pro


Torsional Buckling.

=+ −

χLTZ

ϕ ϕ λ

1

LTZ LTZ LTZ2 2

Zecz = Elastic Section Modulus of the section about Major Axis forthe compression side.

Zetz = Elastic Section Modulus of the section about Major Axis forthe tension side.

=

+

M GIcr

π EI

Lt

π EI

L

y

LT

w

LT

2

2

2

2

Iy = Moment of inertia about the minor axis.

LLT = Effective length for lateral torsional buckling as determinedusing either the KX or LX parameters.

It = Torsional constant of the section.

It = Warping constant of the section.

G = Shear modulus of the material.

ii. About the minor axis, the permissible bending stress is calculated as for alaterally supported section.

Slender Sections

For member with slender section subjected to bending, moment is taken by flanges alone.Design bending strength should be calculated with effective elastic modulus disregarding thecontribution of web of the section.

Zez = 2·[Bf · tf3/12 + (Bf · tf) · (D/2 - tf/2)

2 )] ⁄ (0.5 · D)

Zey = 2·(Bf · tf3/12) ⁄ (0.5 · Bf)

Where:

Zez = Elastic Section modulus about major principal axis.

Zey = Elastic Section modulus about minor principal axis.

Bf = Width of flange.

Tf = thickness of flange.

D = Overall depth of section.

The Moment Capacity will be Md = Ze· fy/γm0 for “Laterally Supported” condition.

The Moment Capacity will be Md = Ze· fbd/γm0 for “Laterally Un-Supported” condition.


Where, fbd is defined in clause 8.2.2 of IS:800-2007 (described in previous Working StressDesign section).

Note: Slender section can only attain elastic moment capacity and cannot reach to plasticmoment capacity.

11F.2.7 Combined Interaction Check

Members subjected to various forces – axial, shear, moment, torsion - are checked againstcombined interaction check.

Limit State Method

This interaction check is done taking care of two aspects:

l Section Strength

l Overall Member Strength

Section Strength interaction ratio is calculated as per sec. 9.3.1 of the code.

Overall Member Strength interaction ratio is calculated as per sec. 9.3.2, taking care of thedesign parameters PSI, CMX, CMY and CMZ.


The following interactions are considered:

a. Combined Bending and Shear — No reduction in allowable stresses for the interactionof bending and shear is considered.

b. Combined Axial Compression and Bending — The following formulas are intended torequire member stability:

fc/facy + 0.6·Ky(Cmyfbcy/fabcy) + KLTfbcz/fabcz ≤ 1.0

fc/facz + 0.6·Ky(Cmyfbcy/fabcy) + Kzfbcz/fabcz ≤ 1.0

fc/(0.6fy) + fbcy/fabcy + fbcz/fabcz ≤ 1.0

Where:

fc = Actual axial compressive stress.

facy, facz = Allowable compressive stress, governed by buckling, about thelocal Y and Z axis, respectively.

fbcy, fbcz = Actual bending compressive stress about minor and majoraxes, respectively.

529— STAAD.Pro


fabcy, fabcz = Allowable bending compressive stress about minor and majoraxes, respectively.

Ky = 1 + (λy - 0.2)·ny ≤ 1 + 0.8·nyKz = 1 + (λz - 0.2)·nz ≤ 1 + 0.8·nzKLT = 1 - 0.1·λLT·ny/(CmLT - 0.25) ≥ 0.1·ny/(CmLT - 0.25)

c. Combined Axial Tension and Bending — The following formulas are intended torequire member stability:

ft/fat + fbty/fabty + fbtz/fabtz ≤ 1.0

Where:

ft = Actual axial tensile stress.

fat = Allowable axial tensile stress.

fbty, fbtz = Actual bending tensile stress about minor and major axes,respectively.

fabty, fabtz = Allowable bending tensile stress about minor and major axes,respectively.

11F.3 Member Property SpecificationFor specification of member properties, the specified steel section available in Steel SectionLibrary of STAAD may be used (namely: I-shaped section, Channel, Tee, HSS Tube, HSS Pipe,Angle, Double Angle, or Double Channel section).

Member properties may also be specified using the User Table facility except for the Generaland Prismatic member types.

For more information on these facilities, refer to Section 1.7 the STAAD Technical ReferenceManual.

11F.3.1 Star Angle Arrangements

STAAD.Pro can design "star angle" sections (double angles, toe to toe) per IS 800:2007.Members using this section must be axial only (i.e., use TRUSS specification). It is assumed thatthe star angle arrangement is a welded shape. Plated shapes are not accounted for in theprogram

Note: This feature requires STAAD.Pro V8i (SELECTseries 4) or higher.

The internal cross section properties are calculated for the principal axes and are checked forTension and Compression limit states as described in this section.


11F.4 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in thefollowing table.

ParameterName


CODE - Must be specified as IS800 LSD



ALPHA 0.8 A Factor, based on the end-connection type, controlling theRupture Strength of the Net Section,as per Section 6.3.3:

0.6 = For one or two bolts0.7 = For three bolts0.8 = For four or more bolts

ATG None(Mandatoryfor Block

Shear check)

Minimum Gross Area in Tension fromthe bolt hole to the toe of the angle,end bolt line, perpendicular to theline of the force.

This parameter is applicable onlywhen DBS = 1.0 (as per Section 6.4.1).

ATN None(Mandatoryfor Block

Shear check)

Minimum Net Area in Tension fromthe bolt hole to the toe of the angle,end bolt line, perpendicular to theline of the force.


AVG None(Mandatoryfor Block

Shear check)

Minimum Gross Area in shear alongbolt line parallel to external force.


Table 11F.1-Indian Steel Design IS 800:2007 Parameters

531 — STAAD.Pro


ParameterName


AVN None(Mandatoryfor Block

Shear check)

Minimum Net Area in shear alongbolt line parallel to external force.


BEAM 1.0 0.0 = design at ends and thoselocations specified by theSECTION command.

1.0 = design at ends and at every 1/12th

point along member length (default).

0 = Minimum detail1 = Intermediate detail level2 = Maximum detail

CAN 0.0 Beam Type, as per section 8.2.1.2:

0 = non-cantilever beams forbending check and deflectioncheck1 = cantilever beam

CMX 0.9 Equivalent uniform moment factorfor Lateral Torsional Buckling(as perTable 18, section 9.3.2.2)

CMY

CMZ

0.9 Cm value in local Y & Z axes, as perSection 9.3.2.2.

DBS 0.0 Check for Design against Block Shear:

0 = Design against Block Shearwill not be performed1 = Design against Block Shear willbe performed

If DBS = 1.0, Non-Zero Positive valuesof AVG, AVN, ATG, and ATN must besupplied to calculate Block ShearStrength, Tdb.

DFF None(Mandatoryfor deflection

check)

"Deflection Length" / Maximumallowable local deflection.


ParameterName


DJ1 Start Joint ofmember

Joint No. denoting starting point forcalculation of "Deflection Length".


Joint No. denoting end point forcalculation of "Deflection Length".

DMAX 1000 in. Maximum allowable depth.

DMIN 0.0 in. Minimum allowable depth.

FU 420 MPA Ultimate Tensile Strength of Steel incurrent units.

FYLD 250 MPA Yield Strength of Steel in currentunits.

KX 1.0 Effective Length Factor for LateralTorsional Buckling (as per Table-15,Section 8.3.1)

KY 1.0 K value in local Y-axis. Usually, theMinor Axis.

KZ 1.0 K value in local Z-axis. Usually, theMajor Axis.

LAT 0.0 Specifies lateral support of beam, asper Section 8.2.1 and 8.2.2, respectively:

0 = Beam is laterally unsupported1 = Beam is laterally supported

LST 0 Defines the number of longitudinalstiffeners used:

0 = No longitudinal stiffener1 = Longitudinal stiffener isprovided at 0.2D of web from thecompression flange2 = Longitudinal stiffeners areprovided at 0.2D and 0.5D of theweb from the compression flange

LX MemberLength

Effective Length for Lateral TorsionalBuckling (as per Table-15, Section8.3.1)

533— STAAD.Pro


ParameterName


LY MemberLength

Length to calculate Slenderness Ratiofor buckling about local Y axis.

LZ MemberLength

Same as above except in Z-axis(Major).

MAIN 180 Allowable Slenderness Limit forCompression Member (as per Section3.8)

NSF 1.0 Net Section Factor for TensionMember.

TMAIN 400 Allowable Slenderness Limit forTension Member (as per Section 3.8)

PROFILE None Used to search for the lightest sectionfor the profile(s) specified for memberselection. See Section 5.48.1 of theTechnical Reference Manual fordetails.

PSI 1.0 Ratio of the Moments at the ends ofthe laterally unsupported length ofthe beam, as per Section 9.3.2.1:

0.8 = where Factored AppliedMoment and Tension can varyindependently1.0 = For any other case

RATIO 1.0 Permissible ratio of the actual toallowable stresses.

STP 1 Specifies the section type per Table 2and Table 10:

1 = Hot rolled section2 = Welded section

TRACK 0 Controls the levels of detail to whichresults are reported.

0 = Minimum detail1 = Intermediate detail level2 = Maximum detail

TSP 0 Spacing of transverse stiffeners.


ParameterName


TST 0 Used to control transverse stiffeners indesign:

0 = No Transverse Stiffener isprovided1 = Transverse Stiffener is provided

11F.5 Code Checking and Member SelectionBoth Code Checking and Member Selection options are available for the IS 800: 2007 code.



11F.5.1 Example 1

Commands for code checking

UNIT NEWTON METER

PARAMETER 1

CODE IS800 LSD

ALPHA 0.7 ALL

DBS 1 ALL

CAN 1 MEMB 2

PSI 0.8 MEMB 2

TMAIN 350 MEMB 2

TRACK 2 MEMB 2

CHECK CODE MEMB 2

11F.5.2 Example 2

Commands for member selection

UNIT NEWTON METER

PARAMETER 1

CODE IS800 LSD

MAIN 160 MEMB 7

KY 0.8 MEMB 7

KZ 0.9 MEMB 7

535— STAAD.Pro


FYLD 350 ALL

SELECT ALL

11F.6 Verification ExampleCalculate compressive strength, bending strength, and shear strength of laterally supportedplate girder 800-6-200-10 given Fy = 250 MPa and Fu = 420 MPa. Check per the IS800: 2007Limit State Design methodology.

11F.6.1 Solution


E = 2.05(10)5 MPa

Note: This is the default value of the modulus of elasticity for steel used by STAAD.Pro. IS800:2007 specifies that a modulus of 2.0(10)5 MPa should be used.

μ = 0.3

G = E/2.0(1 + μ) = 78,846 MPa

Cross sectional properties:

Ag = 800·6 + 2·(200·10) = 8,800 mm2

Izz = 912.1(10)6 mm4

Iyy =13.35(10)6 mm4

Ryy = √(Iyy⁄Area) = 38.95 mm

Rzz = √(Izz⁄Area) = 321.95 mm

Force:

Fx = 19.644 kN (Compression)

Fy = 1.2 kN

Fz = 2.0 kN

Mx = 0.0 kN·m

My = 10.0 kN·m

Mz = 51.659 kN·m

Section Classification

Flange:

b = (bf - tw)/2 = (200 - 6)/2 = 97 mm

εf = √(250/fy) = √(250/250) = 1.0


b/tf = 97/10 = 9.7 > 9.4·ε, < 13.6·ε

Thus, the flange is considered semi-compact.

Web:

r2 = (Fx/Area)/fy = (19,644 / 8,800)/250 = 0.0089

= =+ +

123.8r

126ϵ

1 2

126(1.0)

1 2(0.0089)2

> 42·ε = 42(1.0) = 42

d/tw = 800/6 = 133.33 > 123.8

Thus, the web is considered slender.

The overall section is classified as slender.

Calculation of compressive strength

Net area of section:

Ae= Ag - (d/tw - 42.0·ε) · tw2 = 8,800 - [133.33 - 42.0(1.0)]·(6)2 = 5,512. mm2

Slenderness ratio:

(kyL/Ry) = 0.33·(5,000) / 38.95 = 42.36

(kzL/Rz) = 1.0·(5,000) / 321.95 = 15.53

Euler buckling stress (per Cl.7.1.2.1 of IS 800:2007):

= = =F MPa1,127cc

π E

KL R

π

( / )

2.05(10)

(42.36)

2

2

2 5

2

Non-dimensional effective slenderness ratio:

= = = 0.471F

F

250

1, 127

y

cc

Imperfection factor, α, is equal to 0.49 and buckling class is c as Tf < 40.0 mm and buckling isabout YY axis (per Table 7 and Table 10 in IS 800:2007).

Partial factor of safety γmo = 1.10

Per Cl.7.1.2.1 of IS 800:2007:

ϕ = 0.5[1 + α(λ - 0.2) + λ2] = 0.5[1 + 0.49(0.471 - 0.2) + (0.471)2] = 0.677

Stress reduction factor, χ

= ≤+ −

χ 1.0

ϕ ϕ λ

1

2 2

= = <+ −

χ 0.86 1.01

0.677 0.677 0.4712 2

fcd = χ·(fy/γmo) = 0.86·(250 / 1.1) = 195.5 MPa

537— STAAD.Pro


Design compressive strength (per Cl.7.1.2 of IS 800:2007):

Pd = Ae·fcd = 5,512.·(195.5) = 1,077 kN

Calculation of bending strength

The web is slender and hence it is disregarded in bending strength calculation.

=

+

×

+

=I mm( )2 200 10 656.1(10)z

200(10)

12

800

2

10

2

26 4

3

Zez = Iz/(820/2) =656.1(10)6/410 = 1.60(10)6 mm3

Iy =2(10)(200)3⁄12 = 13.33(10)6 mm4

Zey = Iy⁄(0.5×Bf) = 13.33(10)6/(0.5×200) = 133,333 mm3

Ixx = 2(Bf · Tf3/3.0) = 2.0[(200)(10)3/3.0] = 133.333(10)3 mm4

For laterally supported beam:

Mdz = Zez · Fy/γmo = 1.60(10)6(250)/1.10 = 364 kN·m

Mdy = Zey · Fy/γmo =133,333(250)/1.1 = 30.3 kN·m

For laterally unsupported beam:

Warping constant:

Iw = (d + Tf)2 · Bf

3 · Tf/24.0 = (800 + 10)2 · 2003 · 10/24.0 = 2.187(10)12 mm6

Elastic lateral torsional buckling moment (per Cl.8.2.2.1 of IS 800:2007):

LLT = 5,000 mm

=

+

M GIcr

π EI

Lxx

π EI

L

y

LT

w

LT

2

2

2

2

=

+

= ⋅kN m78,846 133,333 449.8π π2.05(10) 13.33(10)

5, 000

2.05(10) 2.187(10)

5, 000

2 5 6

2

2 5 12

2

= = =λ 0.943LTZ

Z F

M

( )1.60(10) 250

449.8(10)

ez y

cr

6

6

αLT = 0.49 for welded steel section per Cl.8.2.2 of IS 800:2007

ϕLTZ = 0.5×[1 + αLT (λLTZ - 0.2) + λLTZ2 ] = 1.13

= = =+ − + −

χ 0.574LTZ

ϕ ϕ λ

1 1

1.13 1.13 0.943LTZ LTZ LTZ2 2 2 2

fbdz = (χLTZ· Fy) ⁄ γmo = 0.574(250)/1.1 = 130.4 MPa

Mdz = Zez· fbdz = 1.6(10)6(130.4) = 208.6 kN·m

MdY = (Zey· Fy) / γmo = 133,333(250)/1.1 = 30.30 kN·m


Calculation of shear strength

c = spacing of stiffener = 1000 mm

d = depth of web = 800 mm

c/d = 1000/800 = 1.25 > 1.0

Hence, per Cl.8.4.2.2.(a):

kv = 5.35 + 4.0/(c/d)2 = 7.91

d/Tw = 800/6 = 133.33

=k67 / 5.35 81.47v

Since, d/Tw > 67√(kv⁄5.35), shear strength is governed by shear buckling.

Elastic critical stress of the web

= −

tcr ek π E

µ d T( ),

12 1 /

v

w

2

22

= =⋅

−

82.44π

( )

7.91 2.05(10)

12 1 0.3 133.33

2 5

22

Non-dimensional web slenderness ratio for shear buckling stress:

= = = >⋅

λ 1.323 1.2w

f

t3

410

3 82.44

yw

cr e,

Hence

= = =τ 82.46b

f

λ3

250

3 (1.323)

yw

w2 2

Shear force corresponding to shear buckling = Av · τb

= = =⋅V kN359.5crY

A τ

γ

800(6)(82.46)

1.1

WY b

m0

= = =⋅V kN300.0crY

A τ

γ

200(10)(82.46)

1.1

WZ b

m0

11F.6.2 Comparison

Item Reference STAAD.Pro Difference

CompressiveStrength, Pd(kN)

1,077 1.076(10)3 Negligible

Table 11F.2-IS 800:2007 Verification Problem 1

539— STAAD.Pro


Item Reference STAAD.Pro Difference

Major AxisBendingStrength, Mdz(kN·m)

(Laterallyunsupported)

208.6 208.681 Negligible

Minor AxisBendingStrength, Mdy(kN·m)

(Laterallyunsupported)


Major AxisShearStrength, VcrY(kN)


MInor AxisShearStrength, VcrZ(kN)


11F.6.3 STAAD Input File

STAAD SPACE

START JOB INFORMATION

ENGINEER DATE 22-OCT-08

END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 5 0; 3 5 5 0;

MEMBER INCIDENCES

1 1 2; 2 2 3;


ISOTROPIC STEEL

E 2.05E+008

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005


DAMP 0.03

END DEFINE MATERIAL

START USER TABLE

TABLE 1

UNIT METER KN

WIDE FLANGE

SLEND

0.0088 0.82 0.006 0.2 0.01 0.000912133 1.33477E-005 1.90933E-0070.00492 0.004

END

MEMBER PROPERTY AMERICAN

1 UPTABLE 1 SLEND


2 TABLE ST ISMB500

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED


JOINT LOAD

3 FY -2

MEMBER LOAD

2 UNI GY -2

JOINT LOAD

2 FX 1.2

2 FZ -2

SELFWEIGHT Y -1 ALL

PERFORM ANALYSIS

PRINT SUPPORT REACTION

PRINT MEMBER FORCES

PARAMETER 1

CODE IS800 LSD

CAN 0 MEMB 1

KY 0.33 ALL

STP 2 ALL

TST 1 MEMB 1

TSP 1 MEMB 1

***LATERALLY UNSUPPORTED****

*LAT 1 ALL

TRACK 2 MEMB 1

CHECK CODE MEMB 1

541 — STAAD.Pro


PARAMETER 2

CODE IS800 LSD

CAN 0 MEMB 1

KY 0.33 ALL

STP 2 ALL

TST 1 MEMB 1

TSP 1 MEMB 1

***LATERALLY SUPPORTED****

LAT 1 ALL

TRACK 2 MEMB 1

CHECK CODE MEMB 1

FINISH

11F.6.4 Output

TRACK 2.0 output for the Laterally unsupported check

STAAD.PRO CODE CHECKING - IS-800 2007 (V2.0)

************************************************|----------------------------------------------------------------------------------|| Member Number: 1

|| Member Section: ST SLEND (UPT)

|| Status: PASS Ratio: 0.401 Critical Load Case: 1Location: 0.00 || Critical Condition: Sec. 9.3.1.1

|| Critical Design Forces: (Unit: KN METE)

|| FX: 19.644E+00 C FY: -1.200E+00 FZ:-2.000E+00 || MX: 0.000E+00 MY: -10.000E+00 MZ:51.659E+00 ||----------------------------------------------------------------------------------|| Section Properties: (Unit: CM )

|| AXX: 88.000E+00 IZZ: 91.213E+03RZZ: 32.195E+00|| AYY: 48.000E+00 IYY: 1.335E+03RYY: 3.895E+00|| AZZ: 40.000E+00 IXX: 19.093E+00CW: 2.187E+06|| ZEZ: 2.225E+03 ZPZ: 2.580E+03

|


| ZEY: 133.477E+00 ZPY: 207.200E+00|

|----------------------------------------------------------------------------------|| Slenderness Check: (Unit: METE)

|| Actual Length: 5.000E+00

|| Parameters: LZ: 5.000E+00 LY: 5.000E+00

|| KZ: 1.000 KY: 0.330

|| Actual Ratio: 42.37 Allowable Ratio: 180.00 LOAD: 1 FX:19.644E+00 C |

|----------------------------------------------------------------------------------|| Section Class: Slender; Flange Class: Semi-Compact; WebClass: Slender ||----------------------------------------------------------------------------------|

STAAD.PRO CODE CHECKING - IS-800 2007(V2.0)

************************************************|----------------------------------------------------------------------------------|| Member Number: 1


||----------------------------------------------------------------------------------|| Tension: (Unit:KN METE)

|| Parameters: FYLD: 250.000E+03 FU:420.000E+03 || NSF: 1.000 ALPHA:0.800 DBS: 0 || Capacity: 2.000E+03 As per sec. No.:Cl. 6.2

|| Actual Design Force: 0.000E+00 LC: 0

||----------------------------------------------------------------------------------|| Compression: (Unit:KN METE)

|| Buckling Class: Major: b Minor: c As per Sec. No.:Cl.7.1.2.2 |

| Capacity: 1.076E+03 As per sec. No.:Cl. 7.1.2|

| Actual Design Force: 19.644E+00 LC: 1|

|----------------------------------------------------------------------------------|

543— STAAD.Pro


| Shear: (Unit:KN )|

| Major Axis: Actual Design Force: -1.200E+00 LC: 1Loc: 0.000E+00|

| Capacity: 359.732E+00 As per sec. No.:Cl.8.4.2 |

| Minor Axis: Actual Design Force: -2.000E+00 LC: 1Loc: 0.000E+00|


|----------------------------------------------------------------------------------|| Bending: (Unit:KN METE)

|| Parameters: Laterally Unsupported KX: 1.00 LX:5.000E+00 General || Major Axis: Actual Design Force: 51.659E+00 LC: 1Loc: 0.000E+00|


| Minor Axis: Actual Design Force: -10.000E+00 LC: 1Loc: 0.000E+00|

| Capacity: 30.303E+00 As per sec. No.:Cl.8.2.1.1 |

|----------------------------------------------------------------------------------|| Combined Interaction:

|| Parameters: PSI: 1.00 CMX: 0.900 CMY: 0.900 CMZ:0.900 || Interaction Ratio: 0.401 As per sec. No.:Sec. 9.3.1.1

|| LC: 1 Loc: 0.000E+00

||----------------------------------------------------------------------------------|| Checks Ratio Load Case No. Location fromStart ||

|| Tension 0.000 00.000E+00 || Compression 0.018 10.000E+00 || Shear Major 0.003 10.000E+00 || Shear Minor 0.007 10.000E+00 || Bend Major 0.248 10.000E+00 || Bend Minor 0.340 10.000E+00 |


| Sec. 9.3.1.1 0.401 10.000E+00 || Sec. 9.3.2.2 (Z) 0.210 15.000E+00 || Sec. 9.3.2.2 (Y) 0.233 15.000E+00 ||----------------------------------------------------------------------------------|

TRACK 2.0 output for the laterally supported check

STAAD.PRO CODE CHECKING - IS-800 2007(V2.0)

************************************************|----------------------------------------------------------------------------------|| Member Number: 1


|| Status: PASS Ratio: 0.360 Critical Load Case: 1Location: 0.00 || Critical Condition: Sec. 9.3.1.1

|| Critical Design Forces: (Unit: KN METE)

|| FX: 19.644E+00 C FY: -1.200E+00 FZ:-2.000E+00 || MX: 0.000E+00 MY: -10.000E+00 MZ:51.659E+00 ||----------------------------------------------------------------------------------|| Section Properties: (Unit: CM )

|| AXX: 88.000E+00 IZZ: 91.213E+03RZZ: 32.195E+00|| AYY: 48.000E+00 IYY: 1.335E+03RYY: 3.895E+00|| AZZ: 40.000E+00 IXX: 19.093E+00CW: 2.187E+06|| ZEZ: 2.225E+03 ZPZ: 2.580E+03

|| ZEY: 133.477E+00 ZPY: 207.200E+00

||----------------------------------------------------------------------------------|| Slenderness Check: (Unit: METE)

|| Actual Length: 5.000E+00

|| Parameters: LZ: 5.000E+00 LY: 5.000E+00

|

545— STAAD.Pro


| KZ: 1.000 KY: 0.330|

| Actual Ratio: 42.37 Allowable Ratio: 180.00 LOAD: 1 FX:19.644E+00 C ||----------------------------------------------------------------------------------|| Section Class: Slender; Flange Class: Semi-Compact; WebClass: Slender ||----------------------------------------------------------------------------------|

STAAD.PRO CODE CHECKING - IS-800 2007 (V2.0)

************************************************|----------------------------------------------------------------------------------|| Member Number: 1


||----------------------------------------------------------------------------------|| Tension: (Unit:KN METE)

|| Parameters: FYLD: 250.000E+03 FU:420.000E+03 || NSF: 1.000 ALPHA:0.800 DBS: 0 || Capacity: 2.000E+03 As per sec. No.:Cl. 6.2


||----------------------------------------------------------------------------------|| Compression: (Unit:KN METE)

|| Buckling Class: Major: b Minor: c As per Sec. No.:Cl.7.1.2.2 || Capacity: 1.076E+03 As per sec. No.:Cl. 7.1.2


||----------------------------------------------------------------------------------|| Shear: (Unit:KN )

|| Major Axis: Actual Design Force: -1.200E+00 LC: 1Loc: 0.000E+00|| Capacity: 359.732E+00 As per sec. No.:Cl.8.4.2 || Minor Axis: Actual Design Force: -2.000E+00 LC: 1Loc: 0.000E+00|| Capacity: 299.776E+00 As per sec. No.:Cl.8.4.2 |


|----------------------------------------------------------------------------------|| Bending: (Unit:KN METE)

|| Parameters: Laterally Supported KX: 1.00 LX:5.000E+00 General || Major Axis: Actual Design Force: 51.659E+00 LC: 1Loc: 0.000E+00|| Capacity: 363.710E+00 As per sec. No.:Cl.8.2.1.1 || Minor Axis: Actual Design Force: -10.000E+00 LC: 1Loc: 0.000E+00|| Capacity: 30.303E+00 As per sec. No.:Cl.8.2.1.1 ||----------------------------------------------------------------------------------|| Combined Interaction:

|| Parameters: PSI: 1.00 CMX: 0.900 CMY: 0.900 CMZ:0.900 || Interaction Ratio: 0.360 As per sec. No.:Sec. 9.3.1.1

|| LC: 1 Loc: 0.000E+00

||----------------------------------------------------------------------------------|| Checks Ratio Load Case No. Location fromStart ||

|| Tension 0.000 00.000E+00 || Compression 0.018 10.000E+00 || Shear Major 0.003 10.000E+00 || Shear Minor 0.007 10.000E+00 || Bend Major 0.142 10.000E+00 || Bend Minor 0.340 10.000E+00 || Sec. 9.3.1.1 0.360 10.000E+00 || Sec. 9.3.2.2 (Z) 0.126 15.000E+00 || Sec. 9.3.2.2 (Y) 0.141 15.000E+00 ||----------------------------------------------------------------------------------|

547— STAAD.Pro


Section 12

Japanese Codes


549— STAAD.Pro

12A. Japanese Codes - Concrete Design Per 1991 AIJSTAAD.Pro is capable of performing concrete design based on the Japan code AIJ 2002Architectural Institute of Japan Standards for Structural Calculation of Steel ReinforcedConcrete Structures. Design for a member involves calculation of the amount of reinforcementrequired for the member. Calculations are based on the user specified properties and themember forces obtained from the analysis. In addition, the details regarding placement of thereinforcement on the cross section are also reported in the output.

Design of members per AIJ requires the STAAD Japan Design Codes SELECT Code Pack.

12A.1 Section Types for Concrete DesignThe following types of cross sections for concrete members can be designed:

l For Beams — Prismatic (Rectangular and Square)


12A.2 Member DimensionsConcrete members which will be designed by the program must have certain sectionproperties 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 and 250 mmwidth) and the second set of members, with only depth and no width provided, will beassumed to be circular with a 350 mm diameter.

Warning: It is absolutely imperative that you do not provide the cross section area (AX) asan input.

12A.3 Slenderness Effects and Analysis ConsiderationsSlenderness effects are extremely important in designing compression members. Slendernesseffects result in additional forces being exerted on the column over and above those obtainedfrom the elastic analysis. There are two options by which the slenderness effects can beaccommodated.

The first option is to compute the secondary moments through an exact analysis. Secondarymoments are caused by the interaction of the axial loads and the relative end displacements ofa member. The axial loads and joint displacements are first determined from an elasticstiffness analysis and the secondary moments are then evaluated.


The second option is to approximately magnify the moments from the elastic analysis anddesign the column for the magnified moment. It is assumed that the magnified moment isequivalent to the total moment comprised of the sum of primary and secondary moments.

STAAD provides facilities to design according to both of the above methods. To utilize thefirst method, the command PDELTA ANALYSIS must be used instead of PERFORM ANALYSIS inthe input file. The user must note that to take advantage of this analysis, all the combinationsof loading must be provided as primary load cases and not as load combinations. This is dueto the fact that load combinations are just algebraic combinations of forces and moments,whereas a primary load case is revised during the P-delta analysis based on the deflections.Also, note that the proper factored loads (like 1.5 for dead load etc.) should be provided by theuser. STAAD does not factor the loads automatically. The second method mentioned above isutilized by providing the magnification factor as a concrete design parameter (See theparameter MMAG in Table 10A.1). The column is designed for the axial load and total ofprimary and secondary biaxial moments if the first method is used and for the axial load andmagnified biaxial moments if the second method is used.

12A.4 Beam DesignBeams are designed for flexure, shear and torsion. The program considers 12 equally spaceddivisions of the beam member. However this number can be redefined by NSECTIONparameter. All these sections are designed for flexure, shear and torsion for all load cases. Theresults include design results for most critical load case.

Example

UNIT KG CM


CODE JAPAN

FYMAIN SRR295 ALL

FYSEC SRR295 ALL

FC 350 ALL

CLEAR 2.5 MEM 2 TO 6


DESIGN BEAM 2 TO 9

END CONCRETE DESIGN


Reinforcement for positive and negative moments are calculated on the basis of sectionproperties 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 the actual moment programincreases g value for same pt and checks the satisfactory conditions. If conditions are notsatisfied this procedure continues until g reaches to 1.0 and then pt value is increased keepingg = 1.0. This procedure continues until pt reaches to its maximum value( 2 % ). But if theallowable moment for pt = maximum value and g = 1.0 is lower than the actual moment theprogram gives message that the section fails.

551 — STAAD.Pro

12A. Japanese Codes - Concrete Design Per 1991 AIJ

This program automatically calculates the Bar size and no. of bars needed to design thesection. It arranges the bar in layers as per the requirements and recalculate the effective depthand redesign the sections for this effective depth.

Notes:

a. Beams are designed for MZ only. The moment MY is not considered in flexure 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 for flexuredesign.

d. STAAD beam design procedure is based on the local practice and considering the factthat Japan is a high seismic zone area.


The Design Shear value, QD, is evaluated for the beam. The update effective depth is used tothen calculate the allowable shear stress. The allowable shear stress of concrete, fs, isautomatically calculated from design load type (permanent or temporary) and given density ofconcrete. The program then calculates the required bar size, aw, and spacing of stirrups. Thereinforcement ratio for the stirrup, pw, is calculated for design Bar size and stirrup pitch andall the necessary checking is done.

For seismic loading it is needed to increase shear force ≥ 1.5 times the actual value and this canbe done utilizing the Design Shear Modification factor, k (SMAG parameter) without changingthe Design Moment.

Notes:

a. Stirrups are always assumed to be 2-legged

b. Governing density to determine Light weight or Normal Weight Concrete is 2.3 kg/sq.cm

12A.4.3 Design for Torsion

Torsion design for beam is optional. If the TORSION parameter value is 1.0, the program willdesign the assigned beam(s) for torsion. The program first checks whether extra reinforcementis needed for torsion or not. If additional reinforcement is needed, this additional pt is addedto flexure pt and additional Pw is added to shear design Pw.

12A.5 Column DesignColumns are designed for axial force, MZ moment, MY moment, and shear force. Both theends of the members are designed for all the load cases and the loading which produceslargest amount of reinforcement is called as critical load. If Track 0 or Track 1 is used, designresults will be printed for critical load only. But if Track 2 is used, you can get detailed designresults of that member. The value of Pt needed for minimum axial force, maximum axial force,maximum MZ, maximum MY among all 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 theSMAG parameter is used, column shear force will be multiplied by that value.

Column design is done for Rectangular, Square and Circular sections. For rectangular andsquare sections Pt value is calculated separately for MZ and MY, while for circular sections Pgvalue is calculated for MZ and MY separately.

Column design for biaxial moments is optional. If the BIAXIAL parameter value is 1.0, theprogram will design the column for biaxial moments. Otherwise column design is alwaysuniaxial.

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 and checkingallowable load for that known Pt and known actual eccentricity of the column.

3. If the column is in "zone B" or in "zone C", xn is calculated for given P and Pt andchecking is done for allowable moment, if allowable moment is less than the actualmoment, program increases Pt and this procedure continues until the column designconditions are satisfied or the column fails as the required Pt is higher than Ptmaximum value.

4. If the column is in tension, design is done by considering allowable tensile stress ofsteel only.

5. If biaxial design is requested program solve the following interaction equation

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 Pcap,Mycap and Mzcap and solve the interaction equation again and this process continuesuntil the eqn. is satisfied or the column fails as Pt exceeds its maximum limit.

8. If biaxial design is not requested program assumes that interaction equation is satisfied(if uniaxial design is performed successfully).

9. If the interaction equation is satisfied program determines bar size and calculates no.of bars and details output is written.

12A.5.1 Example

UNIT KGS CMS


CODE JAPAN

FYMAIN SRR295 ALL

FC 210 ALL

CLEAR 2.5 MEMB 2 TO 6

553— STAAD.Pro



END CONCRETE DESIGN

12A.6 Slab/Wall Design To design a slab or a wall, it must first be modeled using finite elements and analyzed. Thecommand specifications are in accordance with Chapter 2 and Chapter 6 of the TechnicalReference Manual.

Elements are designed for the moments Mx and My. These moments are obtained from theelement force output (see Chapter 2 of the Technical Reference Manual). The reinforcementrequired to resist the Mx moment is denoted as longitudinal reinforcement and thereinforcement required to resist the My moment is denoted as transverse reinforcement.

The longitudinal bar is the layer closest to the exterior face of the slab or wall. The followingparameters 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 bar. This isconsidered the same on both top and bottom surfaces of the element.

4. MINMAIN—Minimum required size of longitudinal/transverse reinforcing bar

The other parameters shown in Table 12A.1 are not applicable to slab or wall design.

12A.7 Design ParametersThe program contains a number of parameters which are needed to perform the design.Default parameter values have been selected such that they are frequently used numbers forconventional design requirements. These values may be changed to suit the particular designbeing performed. Table 10A.1 contains a complete list of the available parameters and theirdefault values. It is necessary to declare length and force units as centimeters and Kilogramsbefore performing the concrete design.


ParameterName


CODE - Must be specified as JAPAN.


Table 12A.1-Japanese Concrete Design Parameters


ParameterName


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.

DEPTH YD Depth of concrete member. This valuedefaults to YD as provided underMEMBER 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 for steelgrade and their associated yield stressvalues are shown in the followingtable. Program automaticallycalculates yield stress value dependingon design load type (permanent ortemporary).

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 Maximum main reinforcement bar size

MAXSEC 41.0 cm Maximum secondary reinforcementbar size.

MINMAIN 10 mm Minimum main reinforcement barsize.

MINSEC 10 mm Minimum secondary reinforcementbar size.

555— STAAD.Pro


ParameterName


MMAG 1.0 Design moment magnification factor

NSECTION 12 Number of equally-spaced sections tobe considered in finding criticalmoments for beam design.

REINF 0.0 Tied Column. A value of 1.0 will meanspiral.

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 design forbeam

0. torsion design not needed

1. torsion design needed


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 criticalload case only.

2. Design results for minimum P,maximum P, maximum MZand maximum MY among allload cases for both ends.

WIDTH ZD Width of concrete member. This valuedefaults to ZD as provided underMEMBER PROPERTIES.


SteelGrade

Long Term Loading Short Term Loading

Tension& Compressi-

on

ShearRein-

forcement

Tension& Compressi-

on

ShearRein-

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 12A.2-Table of permissible Steel Grades and associated Yield Stressesfor FYMAIN and FYSEC parameters

557— STAAD.Pro


12B. Japanese Codes - Steel Design Per 2005 AIJSTAAD.Pro is capable of performing steel design based on the Japanese code AIJ 2005Specifications for structural steel design.

Design of members per AIJ 2005 requires the STAAD Japan Design Codes SELECT Code Pack.

12B.1 GeneralThis section presents some general statements regarding the implementation of the“Architectural Institute of Japan” (AIJ) specifications for structural steel design (2005 edition)in STAAD. The design philosophy and procedural logistics are based on the principles of elasticanalysis and allowable stress design. Facilities are available for member selection as well as codechecking. Two major failure modes are recognized: failure by overstressing and failure bystability considerations. The following sections describe the salient features of the designapproach.

Members are proportioned to resist the design loads without exceedance of the allowablestresses or capacities and the most economical section is selected on the basis of the leastweight criteria. The code checking part of the program also checks the slendernessrequirements and the stability criteria. Users are recommended to adopt the following steps inperforming 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.


The method for calculating allowable bending stress was updated for the AIJ 2005 from the AIJ2002 code. All other allowable limit states, analysis and design methods, etc., remainunchanged. Refer to the AIJ 2002 documentation for additional details.

12B.2 Member CapacitiesMember design and code checking per AIJ 2005 are based upon the allowable stress designmethod. It is a method for proportioning structural members using design loads and forces,allowable stresses, and design limitations for the appropriate material under service conditions.The basic measure of member capacities are the allowable stresses on the member undervarious conditions of applied loading such as allowable tensile stress, allowable compressivestress etc. These depend on several factors such as cross sectional properties, slenderness factors,unsupported width to thickness ratios and so on. Explained here is the procedure adopted inSTAAD for calculating such capacities.

12B.2.1 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 will automatically adoptthe design procedure for that particular shape if Steel Design is requested. STEEL TABLEavailable within STAAD or UPTABLE facility can be used for member property.


12B.2.2 Methodology

For steel design, STAAD compares the actual stresses with the allowable stresses as requiredby AIJ specifications. The design procedure consist of following three steps.

1. Calculation of sectional properties

The program extract sectional properties like sectional area ( A ), Moment of Inertiaabout Y axis and Z axis ( Iyy, Izz) from in-built Japanese Steel Table and calculates Zz,Zy, iy, iz using appropriate formula. For calculation of i ( radius of gyration needed forbending ), program calculates moment of inertia ( Ii )and sectional area ( Ai ) for 1/6thsection and then uses following formula:

i = √(Ii/Ai)

Note: The above mentioned procedure for calculation of i is applicable for 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

=

≤

>

−

fλ

λ

when Λ

when Λ

c

F

ν

F

( )

( )

1 0.4

0.227

λ

λ

Λ

2

Λ

2

= fc x 1.5 (for Temporary case)

Where:

=Λ π E

F0.6

2

= +ν ( )λ3

2

2

3 Λ

2

559— STAAD.Pro

12B. Japanese Codes - Steel Design Per 2005 AIJ

ii. Bending Stress:

Actual bending stress for My for compression:

( Fbcy) = My / ZcyActual bending stress for Mz for compression

( Fbcz) = Mz / ZczActual bending stress for My for tension

( Fbty ) = My / ZtyActual bending stress for Mz for tension

( Fbtz ) = Mz / ZtzWhere:

Zcy , Zcz are section modulus for compression

Zty, Ztz are section modulus for tension

Allowable bending stress for My

(fbcy) = ftAllowable bending stress for Mz

When λb ≤ pλb, fb = F/ν

When pλb < λb ≤ eλb,

=

−

−

−fb

F

ν

1 0.4

λ b λpb

λ beλpb

When eλb < λb,

=fb λ

F1

2.17b2

Where:

=λ M M/b y e

=λ 1 / 0.6e b

For Temporary case, fbcz = 1.5 x (fbcz for Permanent case)

Where:

C = 1.75 - 1.05 (M2 / M1) + 0.3 (M2 / M1)2

Allowable bending stress for My, fbty = ftAllowable bending stress for Mz, fbtz = fbcz


Note: The parameter CB can be used to specify a value for C directly.

iii. Shear Stress

Actual shear stresses are calculated by the following formula:

qy = Qy / Aww

Where:

Aww = web shear area = product of depth and web thickness

qz = Qz / Aff

Where:

Aff = flange shear area = 2/3 times total flange area

Allowable shear stress, fs = Fs / 1.5, Fs = F / √(3)

3. Checking design requirements:

User provided RATIO value (default 1.0) is used for checking design requirements:

The following conditions are checked to meet the AIJ specifications. For all theconditions calculated value should not be more than the value of RATIO. If for anycondition value exceeds RATIO, program gives the message that the section fails.

Conditions:

i. Axial tensile stress ratio = FT / ftii. Axial compressive stress ratio = FC / fciii. Combined compression & bending ratio = FC / fc+Fbcz/fbcz+Fbcy/fbcyiv. Combined compression & bending ratio = (Fbtz+Fbty-FC) / ftv. Combined tension & bending ratio = (FT+Fbtz+Fbty) / ftvi. Combined tension & bending ratio = Fbcz/fbcz+Fbcy/fbcy- FT/ftvii. Shear stress ratio for qy = qy / fsviii. Shear stress ratio for qz = qz / fsix. von Mises stress ratio (if the von Mises stresses were set to be checked) = fm/

(k⋅ft)

Note: All other member capacities (axial tension, axial compression, and shear) arecalculated as for AIJ 2002. See "Member Capacities" on page 577

12B.3 Design ParametersYou are allowed complete control over the design process through the use of parametersmentioned in Table 12B.1 of this chapter. These parameters communicate design decisions

561 — STAAD.Pro


from the engineer to the program. The default parameter values have been selected such thatthey are frequently used numbers for conventional design. Depending on the particular designrequirements of the situation, some or all of these parameter values may have to be changed toexactly model the physical structure.


ParameterName


CODE - Must be specified as JAPANESE 2005 toinvoke the AIJ 2005.



BEAM 0.0 0.0 = design only for end moments orthose at locations specified by theSECTION command.

1.0 = calculate moments at twelfthpoints along the beam, and use themaximum Mz location for design.

CAN 0 Specifies the method used fordeflection checks

0. deflection check based on theprinciple that maximumdeflection occurs within thespan between DJ1 and DJ2.

1. deflection check based on theprinciple that maximumdeflection is of the cantilevertype (see note a)

Table 12B.1-Japanese Steel Design Parameters


ParameterName


CB 0 C value from the AIJ code. See"Member Capacities" on page 577Bending Stress for how C is calculatedand applied.

Use 0.0 to direct the program tocalculated Cb.

Any other value be used in lieu of theprogram calculated value.

DFF None(Mandatory

fordeflectioncheck)

"Deflection Length" / Maxm. allowablelocal deflection


Joint No. denoting starting point forcalculation of "Deflection Length" (SeeNote b)


Joint No. denoting end point forcalculation of "Deflection Length" (SeeNote b)

DMAX 100 cm Maximum allowable depth formember.

DMIN 0.0 cm Minimum allowable depth formember.

FYLD 235 MPA Yield strength of steel in Megapascal.



LY MemberLength


LZ MemberLength

Same as above except in z-axis

MAIN 0.0 0.0 = check for slenderness

1.0 = suppress slenderness check

563— STAAD.Pro


ParameterName


MISES 0 Option to include check for vonMises stresses

0 = Do not include check.

1 = Perform Von Mises stress check.



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.

TMAIN 400 Allowable Slenderness Limit forTension Member

1.0 = suppress slenderness check .

Any value greater than 1 = AllowableKL/r in tension.

TMP 0 0 = Permanent Loading

1 = Temporary Loading


0. = Suppress critical memberstresses

1. = Print all critical memberstresses

2. = Print expanded output

3. = Print maximum details.

Note: Only produces resultswhen BEAM 0 is used.

4. = Perform and print deflectioncheck.

UNF 1.0 Same as above provided as a fraction ofactual member length.


ParameterName


UNL MemberLength

Unsupported length for calculatingallowable bending stress.

12B.3.1 Notes

a. When performing the deflection check, you can choose between two methods. Thefirst method, defined by a value 0 for the CAN parameter, is based on the localdisplacement. See Section 5.44 of the Technical Reference Manual for details on localdisplacement.

If the CAN parameter is set to 1, the check will be based on cantilever style deflection.Let (DX1, DY1,DZ1) represent the nodal displacements (in global axes) at the nodedefined by DJ1 (or in the absence 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 = − + − + −(DX2 DX1) (DY2 DY1) (DZ2 DZ1)2 2 2

Compute Length = distance between DJ1 and DJ2 or, between start node and endnode, as the case may be.



b. If CAN = 0, the "Deflection Length" is defined as the length that is used for calculationof local 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, in somesituations, the "Deflection Length" may be different. A straight line joining DJ1 andDJ2 is used as the reference line from which local deflections are measured.

For example, refer to the figure below where a beam has been modeled using fourjoints and three members. The “Deflection Length” for all three members will be equalto the total length of the beam in this case. The parameters DJ1 and DJ2 should beused to model this situation. Thus, for all three members here, DJ1 should be 1 andDJ2 should be 4.


PARAMETERS

565— STAAD.Pro


DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

c. If DJ1 and DJ2 are not used, "Deflection Length" will default to the member length andlocal deflections will be measured from original member line.

d. The above parameters may be used in conjunction with other available parameters forsteel design.

12B.4 Von Mises Stresses Check


The von Mises stress equation shown below, which is modified for beam elements based onthe corresponding equation in AIJ steel design code (both 2002 and 2005 editions of AIJ),indicates that the left-hand side in the equation should be less than unity. These checks areperformed at locations indicated by the BEAM parameter. The default is set that this check isnot performed. The MISES parameter must be set to 1 to initiate the checks.

Note: As with other design checks, the unity check value can be modified by use of theRATIO parameter.

The von Misers stresses are evaluated and checked as follows:

<+

1.0σ τ

f

3x xy2 2

Where:

Longitudinal stress in beam element:

= + +σxF

A

M

Z

M

Z

x

x

y

y

z

z

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

= + +τxyM

Z

F

A

F

A

2 2

x

x

y

y

z

z


Mx = Torsional moment

Fy = shear stress in y direction

Fz = shear stress in z direction

Zx = Torsional section modulus

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

In the STRESSES output category, stress value of (numerator of the von Mises stress equation)is output as the value of fm. Along with slenderness ratios, stresses, and deflections, von Misesstress equation is checked. When its left-hand side yields the maximum ratio value, it isprinted as RATIO and “VON MISES” is printed as CRITICAL COND.

12B.5 Verification ProblemsIn the next few pages are included verification examples for reference purposes.


A slender, cantilever beam subjected to a load at the end. Static analysis, 3D beam element.

Problem

A cantilever beam of length 0.3 meters is subjected to a permanent joint load of 3 kN in the Ydirection and 2 kN in the Z direction as well as a 0.008 kN·m torque applied at the end. Axialtension of 10 kN is also applied to the member. An H100x50x5 section is used from theJapanese steel tables.

Given

Section properties

D = 100 mm, B = 50 mm, tf = 7 mm, tw = 5 mm

Ix = 15,000 mm4

Ax = 1185 mm2, Ay = 500 mm

2, Az = 467 mm2

Zx = Ix/tmax = 15,000/7 = 2,143 mm3, Zy = 5,920 mm

3, Zz = 37,400 mm3

The maximum of the left hand side of the von Mises stress equation apparently occurs at thefixed end of the beam. Section forces at the fixed end are ass follow:

-10.0 kN (Tension)

567— STAAD.Pro


0.6 kN·m (Bending-Y)

0.9 kN·m (Bending-Z)

-3.0 kN (Shear-Y)

-2.0 kN (Shear-Z)

-0.008 kN·m (Torsion

Material

FYLD = 300 MPa

E = 2.05E+05 MPa

G = E/2.6 MPa

Solution

From these section forces, σx and τxy at the section of the fixed end are calculated as follows:

= + +σxF

A

M

Z

M

Z

x

x

y

y

z

z= + +− −10, 000

1, 185

600, 000

5, 920

900, 000

37, 400 = 8.44 + 101.35 + 24.06 = 133.85N/mm2

= + +τxyM

Z

F

A

F

A

2 2

x

x

y

y

z

z= + +− − −8, 000

2, 143

3, 000

500

22, 000

467

2

= + +3.73 6 4.282 2 = 11.10

N/mm2

From σx and τxy, fm is calculated:

= + = + =f σ τ3 (133.85) 3(11.10) 135.22m x xy

2 2 2 2N / mm

2

Since ft = FYLD/1.5 = 300.0 MPa/15 = 200.0 N/mm2 and k = 1 for permanent loading,

Ratio = 135.22/(200.0 · 1) = 0.676 < 1, So OK.

Comparison

HandCalculation

STAAD.ProResult

Comments

von Mises Stress, fm(N/mm2)

135.22 135.2 None

Table 12B.2-Comparison of results for a AIJ 2005 verification problem

STAAD Input File

STAAD SPACE VERIFICATION EXAMPLE NO.1START JOB INFORMATIONENGINEER DATE 18-AUG-10


END JOB INFORMATION* VERIFICATION FOR VON MISES STRESSES IN AIJ 2005UNIT MMS KNJOINT COORDINATES1 0 0 0; 2 300 0 0MEMBER INCIDENCES1 1 2UNIT METER KNDEFINE MATERIAL STARTISOTROPIC STEELE 2.05E+008POISSON 0.3DENSITY 76.8195ALPHA 1.2E-005DAMP 0.03END DEFINE MATERIALMEMBER PROPERTY JAPANESE1 TABLE ST H100X50X5UNIT MMS KNCONSTANTSMATERIAL STEEL ALLSUPPORTS1 FIXEDUNIT METER KNLOAD 1 LC1JOINT LOAD2 FX 10 FY 3 FZ 2 MX 0.008PERFORM ANALYSISLOAD LIST 1PRINT MEMBER FORCES LIST 1PARAMETER 1CODE JAPANESE 2005TMP 0 ALLUNL 0.002 ALLMISES 1 ALLTRACK 2 ALLFYLD 300000 ALLCHECK CODE ALLFINISH

Output

The TRACK 2.0 output portion is as follows:

STAAD.PRO CODE CHECKING - ( AIJ 2005) v1.0********************************************

|--------------------------------------------------------------------------|| 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 |

569— STAAD.Pro


| * |<---LENGTH (ME= 0.30 --->| iY = 1.12 ||************* iZ = 3.97 || ZX = 2.14 || 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 = 135.2 || MAX FORCE/ MOMENT SUMMARY (KN-MET) Sx = 133.9 || ------------------------- Tou = 11.1 || || 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) *||* -------------- *||* *||* RESULT/ CRITICAL COND/ RATIO/ LOADING/ *|| FX MY MZ LOCATION || ====================================================== || PASS VON MISES 0.676 1 || 10.00 T 0.60 -0.90 0.000 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|


571 — STAAD.Pro

12C. Japanese Codes - Steel Design Per 2002 AIJSTAAD.Pro is capable of performing steel design based on the Japanese code AIJ 2002Specifications for structural steel design.

Design of members per AIJ 2002 requires the STAAD Japan Design Codes SELECT Code Pack.

12C.1 GeneralThe design philosophy and procedural logistics are based on the principles of elastic analysisand allowable stress design. Facilities are available for member selection as well as codechecking. Two major failure modes are recognized: failure by overstressing and failure bystability considerations. The following sections describe the salient features of the designapproach.

Members are proportioned to resist the design loads without exceedance of the allowablestresses or capacities and the most economical section is selected on the basis of the leastweight criteria. The code checking part of the program also checks the slendernessrequirements and the stability criteria. Users are recommended to adopt the following steps inperforming 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.


12C.2 Analysis MethodologyElastic analysis method is used to obtain the forces and moments for design. Analysis is donefor the primary and combination loading conditions provided by the user. The user is allowedcomplete flexibility in providing loading specifications and in using appropriate load factors tocreate necessary loading situations. Depending upon the analysis requirements, regularstiffness analysis or P-Delta analysis may be specified. Dynamic analysis may also be performedand the results combined with static analysis results.

12C.3 Member Property SpecificationsFor specification of member properties of standard Japanese steel shapes, the steel sectionlibrary available in STAAD may be used. The next section describes the syntax of commandsused to assign properties from the built-in steel table. Members properties may also bespecified using the User Table facility. For more information on these facilities, refer to Section1.7 the STAAD Technical Reference Manual.

12C.4 Built-in Japanese Steel Section LibraryThe following information is provided for use when the built-in steel tables are to bereferenced for member property specification. These properties are stored in a database file. Ifcalled for, these properties are also used for member design. Since the shear areas are built intothese tables, shear deformation is always considered for these members during the analysis. Anexample of member property specification in an input file is provided at the end of thissection.


A complete listing of the sections available in the built-in steel section library may beobtained using the tools of the graphical user interface.


12C.4.1 I shapes

I shapes are specified in the following way:

Note:While specifying the web thickness, the portion after the decimal point should beexcluded.

1 TO 9 TA ST I300X150X11

12 TO 15 TA ST I350X150X9

12C.4.2 H shapes

H shapes are specified as follows:


1 TO 8 TA ST H200X100X4

13 TO 17 TA ST H350X350X12

12C.4.3 T shapes

T shapes are specified as follows:

573— STAAD.Pro

12C. Japanese Codes - Steel Design Per 2002 AIJ


20 TO 25 TA ST T250X19

12C.4.4 Channels

Channel sections are specified as follows.

25 TO 34 TA ST C125X65X6

46 TO 49 TA ST C200X90X8

12C.4.5 Double Channels

Back to back double channels, with or without a spacing in between them, are available. Theletter D in front of the section name is used to specify a double channel. Front-to-front doublechannels are similarly added by adding FR in front of the section name.

17 TO 27 TA D C300X90X10

45 TO 76 TA D C250X90X11 SP 2.0

28 TO 30 TA FR C200X90X8 SP 2.5

In the above commands, members 17 to 27 are a back-to-back double channels C300X90X10with no spacing in between. Members 45 to 76 are a double channels C250X90X11 with aspacing of 2 length units. Members 28 to 30 are front-to-front double channels C200X90X8with a spacing of 2.5 length units.


12C.4.6 Angles

Two types of specification may be used to describe an angle. The standard angle specificationis as follows.

The letter L (signifying that the section is an angle) is followed by the length of the legs andthen the thickness of the leg, all in millimeters. The word ST signifies that the section is astandard angle meaning that the major principal axis coincides with the local YY axisspecified in Chapter 1 of Section 1.5.2 of the Technical Reference Manual.

1 4 TA ST L150X90X9

If the minor principal axis coincides with the local YY axis specified in Chapter 2 of the User'sManual, the word RA (Reverse Angle) should be used instead of ST as shown below.

7 TO 23 TA RA L90X75X9

12C.4.7 Double angles

Short leg back-to-back and long leg back-to-back double angles may be specified by using thewords SD or LD in front of the angle size. In the case of an equal angle, either SD or LD willserve the purpose. The spacing between the angles may be specified by using the word SP afterthe angle size followed by the value of the spacing.

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 of 100X65X7angles separated by 2 length units. The latter is a long legs back-to-back double anglecomprised of 300X90X11 angles separated by 3 length units.

12C.4.8 Tubes

Tube names are input by their dimensions. For example,


is a tube that has a height of 8 length units, width of 6 length units and a wall thickness of0.5 length units. Only code checking, no member selection can be performed on TUBEsections.

575— STAAD.Pro


12C.4.9 Pipes (General Pipe sections)

Circular hollow sections defined by JIS G3444:2005 Design Standard for Steel Structures -Based on Allowable Stress Concept as general pipe sections are specified as shown in thefollowing example.

1 TO 9 TA ST PIPE PIP267.4X7.0

specifies a pipe with outside diameter of 267.0 mm and a thickness of 7.0 mm. Only codechecking, no member selection, can be performed on PIPE sections.

12C.4.10 Circular Hollow sections

Circular hollow sections defined by JIS G3475:2005 Design Standard for Steel Structures -Based on Allowable Stress Concept as Architectural pipe sections are specified as shown in thefollowing example.

1 TO 9 TA ST PIPE CHS660.4X16

specifies a pipe with outside diameter of 660.4 mm and a thickness of 16.0 mm. Only codechecking, no member selection, can be performed on CHS sections.

12C.4.11 Rectangular Hollow sections

Rectangular hollow sections defined by JIS G3466:2005 Design Standard for Steel Structures -Based on Allowable Stress Concept are specified as shown in the following example.

1 TO 9 TA ST PIPE RHS200X100X12

specifies a tube with a depth of 200 mm, a width of 100 mm, and a thickness of 12 mm. Onlycode checking, no member selection, can be performed on CHS sections.

12C.4.12 Square Hollow sections

Square hollow sections defined by JIS G3466:2005 Design Standard for Steel Structures - Basedon Allowable Stress Concept are specified as shown in the following example.

1 TO 9 TA ST PIPE SHS200XS00X12

specifies a square tube with a width of 200 mm and a thickness of 12 mm. Only code checking,no member selection, can be performed on CHS 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 TO BACK

8 TA LD L125X75X7 SP 2.0

* DOUBLE ANGLE - SHORT LEG BACK TO BACK

9 TA SD L300X90X11 SP 1.5

* TUBE


* PIPE



FINISH

12C.5 Member CapacitiesMember design and code checking per AIJ 2002 are based upon the allowable stress designmethod. It is a method for proportioning structural members using design loads and forces,allowable stresses, and design limitations for the appropriate material under serviceconditions. The basic measure of member capacities are the allowable stresses on the memberunder various conditions of applied loading such as allowable tensile stress, allowablecompressive stress etc. These depend on several factors such as cross sectional properties,slenderness factors, unsupported width to thickness ratios and so on. Explained here is theprocedure adopted in STAAD for calculating such capacities.

577— STAAD.Pro


12C.5.1 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 will automatically adoptthe design procedure for that particular shape if Steel Design is requested. STEEL TABLEavailable within STAAD or UPTABLE facility can be used for member property.

12C.5.2 Methodology

For steel design, STAAD compares the actual stresses with the allowable stresses as required byAIJ specifications. The design procedure consist of following three steps.

1. Calculation of sectional properties

The program extract sectional properties like sectional area ( A ), Moment of Inertiaabout Y axis and Z axis ( Iyy, Izz) from in-built Japanese Steel Table and calculates Zz,Zy, iy, iz using appropriate formula. For calculation of i ( radius of gyration needed forbending ), program calculates moment of inertia ( Ii )and sectional area ( Ai ) for 1/6thsection and then uses following formula:

=i I A/i i

Note: The above mentioned procedure for calculation of i is applicable for I shape,H shape and Channel sections.

2. Calculation of actual and allowable stresses

Allowable stresses for structural steel under permanent loading shall be determined onthe basis of the values of F given in the following table.


Steel forConstructionStructures

Steel for GeneralStructures

Steel for Welded Structures

Thick-ness

SN400

SNR4-00

STKN-400

SN490

SNR4-90

STKN-490

SS400

STK400

STKR400

SSC400

SWH400

SS4-90

SS5-40

SM40-0

SMA4-00

SM49-0

SM49-0 Y

SMA4-90

STKR-490

STK49-0

SM5-20

SM5-70

t≤ 40 235 325 235 275 375 235 325 355 400

40< t ≤100

215 295 215 255 - 215 295* 335 400

Table 12C.1-Table: Values of F (N/mm2)

* F = 325 N/mm2 when t > 75mm

Note: In checking members for temporary loading be the combination of stressesdescribed in Chap.3, allowable stresses specified in this chapter may beincreases by 50%

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

579— STAAD.Pro


=

≤

>

−

fλ

λ

when Λ

when Λ

c

F

ν

F

( )

( )

1 0.4

0.227

λ

λ

Λ

2

Λ

2

= fc x 1.5 (for Temporary case)

where:

=Λ π E

F0.6

2

= +ν ( )λ3

2

2

3 Λ

2

ii. Bending Stress:

Actual bending stress for My for compression

( Fbcy) = My / ZcyActual bending stress for Mz for compression

( Fbcz) = Mz / ZczActual bending stress for My for tension

( Fbty ) = My / ZtyActual bending stress for Mz for tension

( Fbtz ) = Mz / ZtzWhere:

Zcy , Zcz are section modulus for compression

Zty, Ztz are section modulus for tension

Allowable bending stress for My

(fbcy) = ftAllowable 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 (fbcz for Permanent case)

Where:

C = 1.75 - 1.05 (M2 / M1) + 0.3 (M2 / M1)2

Allowable bending stress for My, fbty = ft


Allowable bending stress for Mz, fbtz = fbcz

Note: The parameter CB can be used to specify a value for C directly.

iii. Shear Stress

Actual shear stresses are calculated by the following formula:

qy = Qy / Aww

Where:

Aww = web shear area = product of depth and web thickness

qz = Qz / Aff

Where:

Aff = flange shear area = 2/3 times total flange area

Allowable shear stress, fs = Fs / 1.5, Fs = F / √(3)


User provided RATIO value (default 1.0) is used for checking design requirements

The following conditions are checked to meet the AIJ specifications. For all theconditions calculated value should not be more than the value of RATIO. If for anycondition value exceeds RATIO , program gives the message that the section fails.


User provided RATIO value (default 1.0) is used for checking designrequirements

The following conditions are checked to meet the AIJ specifications. For all theconditions calculated value should not be more than the value of RATIO. If forany condition value exceeds RATIO, program gives the message that the sectionfails.

Conditions:

i. Axial tensile stress ratio = FT / ftii. Axial compressive stress ratio = FC / fciii. Combined compression & bending ratio = FC / fc+Fbcz/fbcz+Fbcy/fbcyiv. Combined compression & bending ratio = (Fbtz+Fbty-FC) / ftv. Combined tension & bending ratio = (FT+Fbtz+Fbty) / ftvi. Combined tension & bending ratio = Fbcz/fbcz+Fbcy/fbcy- FT/ftvii. Shear stress ratio for qy = qy / fsviii. Shear stress ratio for qz = qz / fs

581 — STAAD.Pro


ix. von Mises stress ratio (if the von Mises stresses were set to be checked) =fm/(k⋅ft)

12C.5.3 Output Format ( TRACK 3 )

One new output format has been introduced which provides details step by step informationof Steel Design for guiding load case only. If Section command is used before Parametercommand this output will provide details information for all the sections specified by SectionCommand.

Note: This output format is available only when the BEAM parameter value is 0 and theTRACK parameter value is 3. If section command is not used design information willbe printed for two ends only. If Member Truss option is used no Shear Designinformation 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

12C.5.4 Allowable stress for Axial Tension

Allowable axial stress in tension is calculated per section 5.1 (1) of the AIJ code. In memberswith axial tension, the tensile load must not exceed the tension capacity of the member. Thetension capacity of the member is calculated on the basis of the member area. STAADcalculates the tension capacity of a given member based on a user supplied net section factor(NSF-a default value of 1.0 is present but may be altered by changing the input value, see Table8B.1) and proceeds with member selection or code checking.

12C.5.5 Allowable stress for Axial Compression

The allowable stress for members in compression is determined according to the procedure ofsection 5.1 (3). Compressive resistance is a function of the slenderness of the cross-section (Kl/rratio) and the user may control the slenderness value by modifying parameters such as KY, LY,KZ and LZ. In the absence of user provided values for effective length, the actual memberlength will be used. The slenderness ratios are checked against the permissible values specifiedin Chapter 11 of the AIJ code.


12C.5.6 Allowable stress for Bending

The permissible bending compressive and tensile stresses are dependent on such factors aslength of outstanding legs, thickness of flanges, unsupported length of the compressionflange (UNL, defaults to member length) etc. The allowable stresses in bending (compressiveand tensile) are calculated as per the criteria of Clause 5.1 (4) of the code.

12C.5.7 Allowable stress for Shear

Shear capacities are a function of web depth, web thickness etc. The allowable stresses in shearare computed according to Clause 5.1 (2) of the code.

12C.6 Combined LoadingFor members experiencing combined loading (axial force, bending and shear), applicableinteraction formulas are checked at different locations of the member for all modeled loadingsituations. Members subjected to axial tension and bending are checked using the criteria ofclause 6.2. For members with axial compression and bending, the criteria of clause 6.1 is used.

12C.7 Design ParametersThe user is allowed complete control over the design process through the use of parametersmentioned in Table 12C.2 of this chapter. These parameters communicate design decisionsfrom the engineer to the program. The default parameter values have been selected such thatthey are frequently used numbers for conventional design. Depending on the particulardesign requirements of the situation, some or all of these parameter values may have to bechanged to exactly model the physical structure.


ParameterName


CODE - Must be specified as JAPANESE 2002to invoke the AIJ 2002.


Table 12C.2-Japanese Steel Design Parameters

583— STAAD.Pro


ParameterName


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, and usethe maximum Mz location fordesign.

CAN 0 Specifies the method used fordeflection checks

0. deflection check based on theprinciple that maximumdeflection occurs within thespan between DJ1 and DJ2.

1. deflection check based on theprinciple that maximumdeflection is of the cantilevertype (see note a)

CB 0 C value from the AIJ code. See"Member Capacities" on page 577Bending Stress for how C iscalculated and applied.

Use 0.0 to direct the program tocalculated Cb.

Any other value be used in lieu of theprogram calculated value.

DFF None(Mandatory fordeflectioncheck)

"Deflection Length" / Maximumallowable local deflection


Joint No. denoting starting point forcalculation of "Deflection Length"(See Note b)


Joint No. denoting end point forcalculation of "Deflection Length"(See Note b)


ParameterName


DMAX 100 cm Maximum allowable depth formember.

DMIN 0.0 cm Minimum allowable depth formember.



LY MemberLength


LZ MemberLength

Same as above except in z-axis

FYLD 235 MPA Yield strength of steel in Megapascal.

MAIN 0.0 Check for slenderness:

0. Perform check for slenderness

1. Suppress slenderness check

MISES 0 Option to include check for vonMises stresses

0. Do not include check.

1. Perform Von Mises stresscheck.



SSY 0.0 Sidesway:

0. Sidesway in local y-axis.

1. No sidesway

SSZ 0.0 Same as above except in local z-axis.

585— STAAD.Pro


ParameterName


TMAIN 400 Allowable Slenderness Limit forTension Member

1.0 = suppress slenderness check .

Any value greater than 1 = AllowableKL/r in tension.

TMP 0 Loading condition:

0. Permanent Loading

1. Temporary Loading


0. = Suppress critical memberstresses

1. = Print all critical memberstresses

2. = Print expanded output

3. = Print maximum details.

Note: Only producesresults when BEAM 0is used.

4. = Perform and print deflectioncheck.

UNL MemberLength

Unsupported length for calculatingallowable bending stress.

UNF 1.0 Same as above provided as a fractionof actual member length.

12C.7.1 Notes

a. When performing the deflection check, you can choose between two methods. The firstmethod, defined by a value 0 for the CAN parameter, is based on the local displacement.See Section 5.44 of the Technical Reference Manual for details on local displacement.

If the CAN parameter is set to 1, the check will be based on cantilever style deflection. Let(DX1, DY1,DZ1) represent the nodal displacements (in global axes) at the node definedby DJ1 (or in the absence of DJ1, the start node of the member). Similarly, (DX2, DY2,DZ2) represent the deflection values at DJ2 or the end node of the member.


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

Compute Length = distance between DJ1 and DJ2 or, between start node and endnode, as the case may be.



b. If CAN = 0, the "Deflection Length" is defined as the length that is used for calculationof local 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, in somesituations, the "Deflection Length" may be different. A straight line joining DJ1 andDJ2 is used as the reference line from which local deflections are measured.

For example, refer to the figure below where a beam has been modeled using fourjoints and three members. The “Deflection Length” for all three members will be equalto the total length of the beam in this case. The parameters DJ1 and DJ2 should beused to model this situation. Thus, for all three members here, DJ1 should be 1 andDJ2 should be 4.


PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

c. If DJ1 and DJ2 are not used, "Deflection Length" will default to the member lengthand local deflections will be measured from original member line.

d. The above parameters may be used in conjunction with other available parameters forsteel design.

12C.8 Code CheckingThe purpose of code checking is to check whether the provided section properties of themembers are adequate to carry the forces transmitted to it by the loads on the structure. Theadequacy is checked per the AIJ requirements.

Code checking is done using forces and moments at specified sections of the members. If theBEAM parameter for a member is set to 1, moments are calculated at every twelfth point alongthe beam, and the maximum moment about the major axis is used. When no sections arespecified and the BEAM parameter is set to zero (default), design will be based on the forces atthe start and end joints of the member. The code checking output labels the members as

587— STAAD.Pro


PASSed or FAILed. In addition, the critical condition, governing load case, location (distancefrom start joint) and magnitudes of the governing forces and moments are also printed.


12C.9 Member SelectionThe member selection process basically involves determination of the least weight memberthat PASSes the code checking procedure based on the forces and moments obtained from the most 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 selected forit. Selection of members whose properties are originally provided from a user table will belimited to sections in the user table.

Note: Member selection cannot be performed on TUBES, PIPES, or members listed asPRISMATIC.


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

CHECK CODE ALL

SELECT ALL

12C.10 Von Mises Stresses Check


The von Mises stress equation shown below, which is modified for beam elements based onthe corresponding equation in AIJ steel design code (both 2002 and 2005 editions of AIJ),indicates that the left-hand side in the equation should be less than unity. These checks areperformed at locations indicated by the BEAM parameter. The default is set that this check isnot performed. The MISES parameter must be set to 1 to initiate the checks.


Note: As with other design checks, the unity check value can be modified by use of theRATIO parameter.

The von Misers stresses are evaluated and checked as follows:

<+

1.0σ τ

f

3x xy2 2

Where:

Longitudinal stress in beam element:

= + +σxF

A

M

Z

M

Z

x

x

y

y

z

z

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

= + +τxyM

Z

F

A

F

A

2 2

x

x

y

y

z

z

Mx = Torsional moment

Fy = shear stress in y direction

Fz = shear stress in z direction

Zx = Torsional section modulus

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

In the STRESSES output category, stress value of (numerator of the von Mises stress equation)is output as the value of fm. Along with slenderness ratios, stresses, and deflections, von Misesstress equation is checked. When its left-hand side yields the maximum ratio value, it isprinted as RATIO and “VON MISES” is printed as CRITICAL COND.

589— STAAD.Pro


Section 13

Mexican Codes


591 — STAAD.Pro

13A. Mexican Codes - Concrete Design Per MEX NTC 1987STAAD.Pro is capable of performing concrete design based on the Mexican code NTC 1987Normas Técnicas Complementarias para Diseño y construcción de Estructuras de Concreto(Complementary Technical Norms for Design and Construction of Concrete Structures).

Design of members per NTC 1987 requires the STAAD Latin American Design CodesSELECT Code Pack.

13A.1 Design OperationsSTAAD has the capabilities for performing concrete design. It will calculate the reinforcementneeded for the specified concrete section. All the concrete design calculations are based on thecurrent: Complementary Technical Standards for the Design and Construction of ConcreteStructures – Nov. 1987. (Normas Técnicas Complementarias para Diseño y construcción deEstructuras de Concreto) of the Mexican Construction Code for the Federal District –Aug. 1993(Reglamento de Construcciones para el Distrito Federal).

13A.2 Section Types for Concrete DesignThe 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 13A.1 - Concrete shape nomenclature for beams and columns


UNIT CM

MEMBER PROPERTY

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 20 cm width)and the second set of members, with only depth and no width provided, will be assumed tobe circular with 20 cm diameter. Note that no area (AX) is provided for these members. Forconcrete design, this property must not be provided. If shear areas and moments of inertiasare not provided, the program calculates these values from YD and ZD. Notice that in theabove example the IZ and IY values provided are actually 50% of the values calculated usingYD 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 represent a T-shapeand a TRAPEZOIDAL shape respectively. Depending on the properties (YD, ZD, YB, ZB, etc.)provided, the program will determine whether the section is rectangular, trapezoidal or T-shaped and the BEAM design will be done accordingly.

13A.4 Design ParametersThe program contains a number of parameters which are needed to perform design by theMexican code. Default parameter values have been selected such that they are frequently usednumbers for conventional design requirements. These values may be changed to suit theparticular design being performed. Table 3.1 is a complete list of the available parameters andtheir default values.

The manual describes the commands required to provide these parameters in the input file.For example, the values of SFACE and EFACE (parameters that are used in shear design), thedistances of the face of supports from the end nodes of a beam, are assigned values of zero bydefault but may be changed depending on the actual situation. Similarly, beams and columnsare designed for moments directly obtained from the analyses without any magnification.The factors MMY and MMZ may be used for magnification of column moments. For beams, theuser may generate load cases which contain loads magnified by the appropriate load factors.


ParameterName

Default Value Parameters

CODE - Must be specified as MEXICAN.



Table 13A.1-Mexican Concrete Design Parameters

593— STAAD.Pro

13A. Mexican Codes - Concrete Design Per MEX NTC 1987

ParameterName


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) todefine Modulus of Elasticity

1. Class 1 Concrete

2. Class 2 Concrete

CFB FALSE Cold formed Bar classification to definedevelopment multipliers according totable 3.1 NTC

l FALSE - Not cold formed bar

l TRUE - Cold formed bar

CLB 3 cm Clear cover for bottom reinforcement

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.

DCP TRUE Beam Loads and reactions in directcompression Cl-2.1.5.a.I 2nd paragraph

l FALSE - Loads applied indirectly

l TRUE - Direct compression

DEPTH YD Depth of concrete member, in currentunits. This value defaults to YD asprovided under MEMBER PROPERTIES.

DIM TRUE l FALSE: Not precautions taken -Section reduction to section 1.5NTC Concrete

l TRUE: Precautions are taken toassure dimensions


ParameterName


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 of beam.If specified, for shear force at start iscomputed at a distance of EFACE+dfrom the start joint of the member.Positive number.

EXP FALSE Exposition to soil or weather to definecover and min Steel reinforcement

l FALSE - Not exposed to soil orweather

l TRUE - Exposed to soil orweather

FC 200 Kg/cm2 Compressive Strength of Concrete

FYMAIN 4,200 Kg/cm2 Yield Stress for main reinforcing steel

FYSEC 4,200 Kg/cm2 Yield Stress for secondary (stirrup)reinforcing steel

LSS 0 Part of the longitudinal steelconsidered to reduce shear. 0 (zero) isconservative. Value between 1 and 0.

LTC FALSE Light Concrete to define developmentmultipliers according to table 3.1 NTC

l FALSE - Regular concrete

l TRUE - Lightweight concrete

MAXMAIN 12 Maximum main reinforcement bar size(Number 2 -18)

MINMAIN 2.5 Minimum main reinforcement bar size(Number 2 -18)

595— STAAD.Pro


ParameterName


MINSEC 2.5 Minimum secondary reinforcement barsize (Number 2 -18)

MMY 1.0 Moment magnification factor forcolumns, about My.

MMZ 1.0 Moment magnification factor forcolumns, about Mz.

MOE 198,000Kg/cm2

Concrete modulus of elasticiy.

NSECTION 12 Number of equally-spaced sections to beconsidered in finding critical momentsfor beam design

PHI 90 degrees Stirrups angle with the axis of theelement

PSS TRUE Slab beared perimeter. To calculate minsteel required according to 2.1.2

REINF 0 Tied Column. A value of 1 will meanspiral.

SFACE 0 Face to support location of start ofbeam. If specified, for shear force atstart is computed at a distance ofSFACE+d from the start joint of themember. Positive number

TEQ FALSE Beam needed for torsional equilibriumCl.2.1.6a) 2nd paragraph

l FALSE - No

l TRUE - Yes


ParameterName


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 intermediatesections 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 schematicinteraction diagram andintermediate interaction valuesin addition to all of the above.

WIDTH ZD Width of concrete member, in currentunits. This value defaults to ZD asprovided under MEMBER PROPERTIES

* These values must be provided in the current unit system being used.

Note:When using metric bars for design, provide values for these parameters in actual‘mm‘ units instead of the bar number. The following metric bar sizes are available:4.2mm, 6 mm, 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 32 mm, 40 mm, 50mm and 60 mm.

13A.5 Beam DesignBeams are designed for flexure, shear and torsion. For all these forces, all active beam loadingsare prescanned to locate the possible critical sections. The total number of sections consideredis 12 (twelve) unless this number is redefined with an NSECTION parameter. All of theseequally spaced sections are scanned to determine moment and shear envelopes.


Reinforcement for positive and negative moments are calculated on the basis of the sectionproperties provided by the user. If the section dimensions are inadequate to carry the applied

597— STAAD.Pro


load, that is if the required reinforcement is greater than the maximum allowable for the crosssection, the program reports that beam fails in maximum reinforcement. Rectangular sectionsare also designed with compression reinforcement.

Effective depth is chosen as Total depth - (Clear cover + diameter of stirrup + half the dia. ofmain reinforcement), and a trial value is obtained by adopting proper bar sizes for the stirrupsand main reinforcements. The relevant clauses in Sections 1.5, 1.6, 2.1.1-2-5, 3.10 and 5.2.2 of NTCConcrete are utilized to obtain the actual amount of steel required as well as the maximumallowable and minimum required steel. These values are reported as ROW, ROWMX andROWMN in the output and can be printed using the parameter TRACK 1.0 (see Table 13A.1).In addition, the maximum, minimum and actual bar spacing are also printed.

It is important to note that beams are designed for flexural moment MZ only. The momentMY is not considered in the flexural design.


Shear reinforcement is calculated to resist both shear forces and torsional moments. Shearforces are calculated at a distance (d+SFACE) and (d+EFACE) away from the end nodes of thebeam. SFACE and EFACE have default values of zero unless provided under parameters (seeTable 13A.1). Note that the value of the effective depth "d" used for this purpose is the updatevalue and accounts for the actual c.g. of the main reinforcement calculated under flexuraldesign. Clauses 2.1.5-6 and 5.2.4 of NTC Concrete are used to calculate the reinforcement forshear forces and torsional moments. Based on the total stirrup reinforcement required, the sizeof bars, the spacing, the number of bars and the distance over which they are provided arecalculated. Stirrups due to geometric conditions are assumed to be 2-legged, due to designconditions could be 2 or 4-legged.

13A.5.3 Design for Anchorage

In the output for flexural design, the anchorage details are also provided. At any particularlevel, the START and END coordinates of the layout of the main reinforcement is describedalong with the information whether anchorage in the form of a hook or continuation isrequired or not at these START and END points. Note that the coordinates of these STARTand END points are obtained after taking into account the anchorage requirements.Anchorage length is calculated on the basis of the Clauses described in Section 3.1 of NTCconcrete. In case the program selects 2 different diameters for the main or compressionreinforcement, only the anchorage for the largest diameter is analyzed.

13A.5.4 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

From


Distance 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 the start (STA)or at the end (END).

RowActually required flexural reinforcement (As/bd) where b = width of cross section(ZD for a rectangular or square section) and d = effective depth of cross section (YDminus the distance from extreme tension fiber to the centroid of mainreinforcement).

ROWMNMinimum required flexural reinforcement (Amin/bd)

ROWMXMaximum 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

Example Output for Beam Design

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

BEAM NO. 2 DESIGN RESULTS - FLEXURE

PER CODE NTC FOR THE DESIGN AND CONSTRUCTION OF CONCRETE STRUCTURES,DDF

LEN - 6000.00(mm) FY - 412. FC - 20. SIZE - 253.75 X 253.75(mm)

LEVEL HEIGHT BAR INFO FROM TO ANCHOR(mm) (mm) (mm) STA END

_____________________________________________________________________

1 42. 5 - 2.MM 2468. 6000. NO YES2 212. 5 - 2.MM 0. 2782. YES NO

B E A M N O. 2 D E S I G N R E S U L T S - SHEAR

AT START SUPPORT - Vu= 5.63 KN Vc= 0.00 KN Vs= 0.00 KNTu= 0.09 Kn Me Tc= 0.00 Kn Me Ts= 0.00 Kn Me LOAD 1

STIRRUPS ARE NOT REQUIRED.

599— STAAD.Pro


AT END SUPPORT - Vu= 5.63 KN Vc= 0.00 KN Vs= 0.00 KNTu= 0.09 Kn Me Tc= 0.00 Kn Me Ts= 0.00 Kn Me LOAD 1

STIRRUPS ARE NOT REQUIRED.

13A.6 Column DesignColumns design in STAAD per the Mexican code is performed for axial force and uniaxial aswell as biaxial moments. All active loadings are checked to compute reinforcement. Theloading which produces the largest amount of reinforcement is called the critical load.Column design is done for square, rectangular and circular sections. For rectangular andcircular sections, reinforcement is always assumed to be equally distributed on all faces. Thismeans that the total number of bars for these sections will always be a multiple of four (4). Ifthe MMAGx & -MMAGy parameters are specified, the column moments are multiplied by thecorresponding MMAG value to arrive at the ultimate moments on the column. Minimumeccentricity conditions 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 design oraccording 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 the section.Ensure that the actual nominal load on the column does not exceed PNMAX. IfPNMAX is less than the axial force Pu/FR, (FR is the strength reduction factor) increasethe reinforcement and repeat steps 2 and 3. If the reinforcement exceeds 6% (or 4% forductile design), the column cannot be designed with its current dimensions.

4. For the assumed reinforcement, bar arrangement and axial load, find the uniaxialmoment capacities of the column for the Y and the Z axes, independently. These valuesare referred to as MYCAP and MZCAP respectively.

5. Solve the Interaction Bresler equation:

(Mny/Mycap)α + (Mnz/Mzcap)

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 sizes, findthe uniaxial capacities and solve the interaction equation again. If the equation issatisfied now, the reinforcement details are written to the output file.

7. If the interaction equation is not satisfied, the assumed reinforcement is increased(ensuring that it is under 6% or 4% respectively) and steps 2 to 6 are repeated.

By the moment to check shear and torsion for columns the sections have to be checked asbeams and the most strict of both shear and torsion reinforcement adopted.


13A.7 Column InteractionThe column interaction values may be obtained by using the design parameter TRACK 1.0 orTRACK 2.0 for the column member. If a value of 2.0 is used for the TRACK parameter, 12different Pn-Mn pairs, each representing a different point on the Pn-Mn curve are printed.Each of these points represents one of the several Pn-Mn combinations that this column iscapable of carrying about the given axis, for the actual reinforcement that the column hasbeen designed for. In the case of circular columns, the values are for any of the radial axes.The values printed for the TRACK 1.0 output are:

l P0 = Maximum allowable pure axial load on the column (moment zero).

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 the axial 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 load case.

l Mu = Ö (Mux.Mmagx)²+ (Muy.Mmagy)²

l e/h = (Mn/Pn)/h where h is the length of the column

13A.8 Column Design OutputThe next table illustrates different levels of the column design output.

The output is generated without any TRACK specification:

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

COLUMN NO. 1 DESIGN PER MEX NTC-87 - AXIAL + BENDING

FY - 411.9 FC - 19.6 MPa SQRE SIZE 25.4 x 25.4 (mm) TIEDAREA OF STEEL REQUIRED = 626.700

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

4 - NUMBER 5 1.230 1 END 0.700(PROVIDE EQUAL NUMBER OF BARS ON EACH FACE)

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)

601 — STAAD.Pro


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

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

13A.9 Slab DesignSlabs are designed per Mexican NTC specifications. To design a slab, it must be modeled usingfinite elements.


Element design will be performed only for the moments MX and MY at the center of theelement. Design will not be performed for FX, FY, FXY, MXY. Also, design is not performedat any other point on the surface of the element. Shear is checked with Q.

A typical example of element design output is shown below. The reinforcement required toresist Mx moment is denoted as longitudinal reinforcement and the reinforcement requiredto resist My moment is denoted as transverse reinforcement. The parameters FYMAIN, FC, CLB,CLS, CLT, DIM, and EXP listed in Table 11A.1 are relevant to slab design. Other parametersmentioned are not used in slab design.


13A.9.1 Example Output for Element DesignELEMENT DESIGN SUMMARY----------------------

ELEMENT LONG. REINF MOM-X /LOAD TRANS. REINF MOM-Y /LOAD(SQ.MM/MM) (KN-MM/MM) (SQ.MM/MM) (KN-MM/MM)

47 TOP : Longitudinal direction - Only minimum steel required.47 TOP : Transverse direction - Only minimum steel required.47 TOP : 0.205 0.00 / 0 0.205 0.00 / 0

BOTT: 0.254 10.44 / 1 0.362 13.35 / 1

47 SHEAR CAPACITY 57.06 KN ***PASS*** FOR LOAD CASE 3

***** INDICATES REINFORCEMENT EXCEEDS MAXIMUM

***************************END OF ELEMENT DESIGN***************************

603— STAAD.Pro


13B. Mexican Codes - Steel Design Per NTC 1987STAAD.Pro is capable of performing steel design based on the Mexican code NTC 1987(Normas Técnicas Complementarias para Diseño y construcción de Estructuras Metálicas)(Complementary Technical Standards for the Design and Construction of Steel Structures –Dec. 1987) or the Reglamento de Construcciones para el Distrito Federal (MexicanConstruction Code for the Federal District –Aug. 1993).

Design of members per NTC 1987 requires the STAAD Latin American Design CodesSELECT Code Pack.

13B.1 GeneralThe design philosophy considered is that of the Load Cases and Resistance Method or LimitStates Design usually known as Load and Resistance Factor Design (LRFD).

Structures are designed and proportioned taking into consideration the limit states at whichthey would become unfit for their intended use. Two major categories of limit-state arerecognized--ultimate and serviceability. The primary considerations in ultimate limit statedesign are strength and stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all steel structures undervarious loading conditions and at the same time the chances of limits being surpassed areacceptably remote.

In the STAAD implementation of the Mexican Standards for steel structures, members areproportioned to resist the design loads without exceeding the limit states of strength, andstability. It allows to check deformation to verify serviceability.

Accordingly, the most economic section is selected on the basis of the least weight criteria asaugmented by the designer in specification of allowable member depths, desired section type,or other such parameters. The code checking portion of the program checks that main coderequirements for each selected section are met and identifies the governing criteria.

The following sections describe the salient features of the Mexican specifications asimplemented in STAAD steel design. A brief description of the fundamental concepts ispresented here.

13B.2 Limit States Design FundamentalsThe primary objective of the Limit States Design Specification is to provide a uniformreliability for all steel structures under various loading conditions.

The Limit States Design Method uses separate factors for each load and resistance. Because thedifferent factors reflect the degree of uncertainty of different loads and combinations of loadsand of the accuracy of predicted strength, a more uniform reliability is possible.

The method may be summarized by the inequality

Yi Qi ≤ Rn FR


On the left side of the inequality, the required strength is the summation of the various loadeffects, Qi, multiplied by their respective load factors, Yi. The design strength, on the rightside, 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 the user will useappropriate load factors and create the load combinations necessary for analysis. The designportion of the program will take into consideration the load effects (forces and moments)obtained from analysis. In calculation of resistances of various elements (beams, columnsetc.), resistance (nominal strength) and applicable resistance factor will be automaticallyconsidered.

13B.3 Member End Forces and MomentsMember end forces and moments in the member result from loads applied to the structure.These forces are in the local member coordinate system. the following figures show themember end actions with their directions. Refer to Section 1.19 of the Technical ReferenceManual for additional details.

13B.4 Section ClassificationThe Limit States Design specification allows inelastic deformation of section elements. Thuslocal buckling becomes an important criterion. Steel sections are classified as compact (type2), noncompact (type 3), or slender element (type 4), sections depending upon their localbuckling characteristics, besides sections type 1 are able for plastic design. This classification isa function of the geometric properties of the section. The design procedures are differentdepending on the section class. STAAD is capable of determining the section classification forthe standard shapes and design accordingly.

13B.5 Member in Axial TensionThe criteria governing the capacity of tension members is based on two limit states. The limitstate of yielding in the gross section is intended to prevent excessive elongation of themember. The second limit state involves fracture at the section with the minimum effectivenet area. The net section area may be specified by the user through the use of the parameterNSF (see Table 13B.1), that always refers to the gross section. STAAD calculates thetension capacity of a given member based on these two limit states and proceeds withmember selection or code check accordingly.

In addition to the tension resistance criterion, the user defines if tension members arerequired to satisfy slenderness limitations which are a function of the nature of use of themember (main load resisting component, bracing member, etc.). In both the memberselection and code checking process, STAAD immediately does a slenderness check onappropriate members before continuing with other procedures for determining the adequacyof a given member.

13B.6 Axial CompressionThe column strength equations take into account inelastic deformation and other recentresearch in column behavior. Two equations governing column strength are available, one forinelastic buckling and the other for elastic or Euler buckling. Both equations include the

605— STAAD.Pro

13B. Mexican Codes - Steel Design Per NTC 1987

effects of residual stresses and initial out-of-straightness. Compression strength for a particularmember is calculated by STAAD according to the procedure outlined in Section 3.2 of theNTC. For slender elements, the procedure described in Section 2.3.6.NTC is also used.

The procedures of Section 3.2 of the Commentaries, design helps and examples of theComplementary Technical Standards for the Design and Construction of Steel Structures (delos Comentarios, ayudas de diseño y ejemplos de las Normas Técnicas Complementarias para elDiseño y Construcción de Estructuras Metálicas, DDF (Comentarios - Julio 1993) wereimplemented for the determination of design strength for these limit states.

Effective length for calculation of compression resistance may be provided through the use ofthe parameters KY, KZ and/or LY, LZ. If not provided, the entire member length will be takeninto consideration.

In addition to the compression resistance criterion, compression members are required tosatisfy slenderness limitations which are a function of the nature of use of the member (mainload resisting component, bracing member, etc.). In both the member selection and codechecking process, STAAD immediately does a slenderness check on appropriate membersbefore continuing with other procedures for determining the adequacy of a given member.

13B.7 Flexural Design StrengthIn the Limit States Design Method, the flexural design strength of a member is determinedmainly by the limit state of lateral torsional buckling. Inelastic bending is allowed and thebasic measure of flexural capacity is the plastic moment capacity of the section.

The flexural resistance is a function of plastic moment capacity, actual laterally unbracedlength, limiting laterally unbraced length, buckling moment and the bending coefficient. Thelimiting laterally unbraced length Lu and flexural resistance Mr are functions of the sectiongeometry and are calculated as per the procedure of Section 3.3.2 of the NTC.

The purpose of bending coefficient Cb is to account for the influence of the moment gradienton lateral-torsional buckling. This coefficient can be specified by the user through the use ofparameter CB or CBy (see Table 11B.1) or may be calculated by the program (according toLRDF USA specification) if CB is specified as 0.0. In the absence of the parameter CB, a defaultvalue of 1.0 will be used.

To specify laterally unsupported length, either of the parameters UNL and UNF (see Table10B.1) can be used.

It is taken into account the reduction of flexural resistance due to slender web according tosection 4.5.8 of the NTC

For the sections where the web and flange are slender the LRDF USA specification was used.

Stress areas due to bending about y axis (MY)


Note: The local X axis goes into the page; the Global Y axis is vertical upwards; theshaded area indicates area under compression; the area not shaded indicates areaunder tension.

Stress areas due to bending about Z axis (MZ)

13B.8 Design for ShearThe procedure of Sect. 3.3.3 of the NTC is used in STAAD to design for shear forces inmembers. Besides combined bending and shear is checked according to section 3.3.4 of theNTC, considering also the limits for stiffeners of the web according to sections 4.5.6/7 of theNTC. Shear in wide flanges and channel sections is resisted by the area of the web/s..

13B.9 Combined Compression Axial Force and BendingThe interaction of flexure and axial forces in singly and doubly symmetric shapes is governedby formulas of the Section 3.4 of the NTC. These interaction formulas cover the general caseof biaxial bending combined with axial force. They are also valid for uniaxial bending andaxial force.

It is considered that the frames are part of structures that have shear walls or rigid elementsso that the lateral displacements of a floor could be disregarded. The program has included

607— STAAD.Pro


formulas to include structures with lateral displacements in the future considering for B2 thecolumns individually and not the complete floor analysis.

It is taken into account if the elements have transverse loads and if the ends are angularlyrestrained.

13B.10 Combined Tension Axial Force and BendingBased on Section 3.5 4 of the NTC.

13B.11 Design ParametersDesign per Mexican Standards is requested by using the CODE. Other applicable parameters aresummarized in Table 11B.1 below. These parameters communicate design decisions from theengineer to the program and thus allow the engineer to control the design process to suit anapplication's specific needs.


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 is specified again.This is the way STAAD works for all codes.

ParameterName


CODE - Must be specified as MEXICAN.



BEAM 0 0: Design at ends and thoselocations specified by SECTION command.

1: Design at ends and at every ycada 1/12th point along memberlength

CB 1 Coefficient C defined per section3.3.2.2. If Cb is set to 0.0 it willbe calculated by the programaccording to LRFD USA(CbMex=1/CbUSA). Any othervalue will be directly used in thedesign.

Table 13B.1-Design Parameters According to Mexican NTC Standards - Steel


ParameterName


CMB 1 Cfactor for combined forceswhen there are transverse loadsin the members. Section 3.4.3.3.iiof NTC

CMB 1.0 =Members ends arerestrictedangularly.

CMB 0.85 =Members ends arenot restrictedangularly.

DFF None(Mandatory fordeflection check,TRACK 4.0)

"Deflection Length" / Maxm.allowable local deflection

See Note 1 below.


Joint No. denoting starting pointfor calculation of "DeflectionLength ."

See Note 1 below.


Joint No. denoting end point forcalculation of "DeflectionLength."

See Note 1 below.

DMAX 114 cm Maximum allowable depth

DMIN 0.0 cm Minimum allowable depth

DSD T Perform the ductile seismicdesign in accordance withSection 11 (True or False).

Main design conditions are considered (not including, at themoment, geometric ones)

FU 4,230 Kg/cm2 Ultimate tensile strength of steel

FYLD 2,530 kg/cm2 Minimum Yield strength of steel

609— STAAD.Pro


ParameterName


IMM 0 Main or secondary member forthe purpose of checkingslenderness

0. Main member

1. Secondary and windtrusses

INO 0 Curve Definition according to NTC.3.2.2.1a, defined for I shapesor tubes

0. n=1.4, laminated I shapes,tubes or built up with 3or 4 welded platesobtained from widerplates cuts with oxygen.

1. n=1, I shapes, tubes orbuilt up with 3 or 4welded plates

IRR 0 Variable defined for the wholestructure indicating if it isregular or irregular according tosection 3.4 of the NTC.

0. Columns that are part ofregular structures

1. Columns that are part ofirregular structures

KX 1.0 Effective length factor for flexural-torsional buckling

KY 1.0 Effective length factor for local Yaxis- Usually minor axis

KZ 1.0 Effective length factor for local Zaxis- Usually major axis


ParameterName


LDR T Defines if the structure has elements to bear the wind load(shear walls, wind trusses, orbracing rigid elements ) thatrestrict lateral displacements andallow to disregard slendernesseffects. (True or False)

LX Member length Length for determining flexural-torsional buckling

LY Member length Length to calculate slendernessratio for buckling about local Yaxis.

LZ Member length Length to calculate slendernessratio for buckling about local Zaxis.

NSF 1 Net section factor for tensionmembers

RATIO 1.0 Permissible ratio of actual loadeffect and design strength

STIFF Longer of Memberlength or depth

Spacing of stiffeners for beamsfor shear design

TRACK 0 Controls the level of detail inoutput

0. = Suppress all designstrengths

1. = Print all designstrengths

2. = Print expanded designoutput

UNB Member length Unsupported length (L) of thebottom* flange for calculatingflexural strength . Will be usedonly if compression is in thebottom flange.

See Note 2 below.

611 — STAAD.Pro


ParameterName


UNT Member length Unsupported length (L) of thetop* flange for calculatingflexural strength . Will be usedonly if compression is in the topflange.

See Note 2 below.

1. For deflection check, parameters DFF, DJ1, and DJ2 from Table 2B.1 may be used. Allrequirements remain the same.

2. Top and Bottom represent the positive and negative side of the local Y axis (local Z axisif SET Z UP is used).

13B.12 Code Checking and Member SelectionBoth code checking and member selection options are available in STAAD Mexican Standardsimplementation.



13B.13 Tabulated Results of Steel DesignResults of code checking and member selection are presented in a tabular format.

CRITICAL COND refers to the section of the Mexican NTC which governed the design.

If the TRACK is set to 1.0, member design strengths will be printed out.


613— STAAD.Pro

Section 14

Norwegian Codes


615— STAAD.Pro

14A. Norwegian Codes - Steel Design per NS 3472 / NPDSTAAD.Pro is capable of performing steel design based on the Norwegian code NS 3472 Steelstructures. Design rules (3rd Edition) and NPD 1993 Veiledning om utforming, beregning ogdimensjonering av stalkonstruksjoner. Sist enderet 1. (Guidance on the design, calculation anddimensioning of figures constructions. Revision 1).

Design of members per NS 3472 / NPD requires the STAAD N. Eurozone Design CodesSELECT Code Pack.

14A.1 - General NotesThis user manual presents a description of the design basis, parameters and theory applied toSTAAD.Pro for performing code checks according to NS 3472 ref. [1] and NPD ref. [5]. Thecode 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 according toNPD

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 available through twoseparate STAAD.Pro Code check packages.

l This document is not a lecture in use of NS 3472 or NPD. This document explains how,and which parts of, the Norwegian steel codes that have been implemented inSTAAD.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) is notidentical to the general prismatic profile defined in the STAAD.Pro analysis package.

EDR does not accept any liability for loss or damage from or in consequence for use of theprogram.

14A.1.1 Nomenclature

NS - refers to NS 3472 ref. [1]

NS2 - refers to NS 3472 ref. [6]

NPD - refers to NPD94 ref. [5]

14A.1.2 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



4. Roark &Young`s 5th edition

5. NPD utg. 1994

Veiledning om utforming, beregning og dimensjonering av stålkonstruksjoner. Sist

endret 1. oktober 1993.

6. NS 3472 2.utg.1984



14A.2 - Basis for Code CheckingThis section presents general information regarding the implementation of the Norwegiancodes of practice for structural steel design. This manual describes the procedures and theoryused for both NS and NPD.

In general NS is used for all cross sections and shapes listed in section 1 of this manual. Anexception is the treatment and check of pipe members in framed structures. NS does not give

617— STAAD.Pro

14A. Norwegian Codes - Steel Design per NS 3472 / NPD

specific details about the treatment of pipes. Section 3.4 explains how this is adopted when NSis selected for code checking.

The NPD however have a more thorough check of pipe members, and consider the effect oflocal buckling of the pipe wall in conjunction with the stability check. In addition, the NPDcode gives joint capacity formulae for brace to chord connections for pipe members.

The design philosophy and procedural logistics are based on the principles of elastic analysisand ultimate limit state design. Two major failure modes are recognized:

l failure by overstressing

l failure by stability considerations

The following sections describe the salient features of the design approach. Members areproportioned to resist the design loads without exceeding the characteristic stresses orcapacities and the most economic section is selected on the basis of the least weight criteria. Itis generally assumed that the user will take care of the detailing requirements like theprovision of stiffeners and check the local effects like flange buckling, web crippling, etc.

The user is allowed complete control over the design process through the use of theparameters listed in Table 2.1. Default values of parameters will yield reasonable results in mostcircumstances. However, the user should control the design and verify results through the useof the design parameters.

14A.2.1 Calculation of Forces and Bending Moments

Elastic analysis method is used to obtain the forces and moments for design. Analysis is donefor the primary loading conditions and combinations provided by the user. The user is allowedcomplete flexibility in providing loading specifications and using appropriate load factors tocreate necessary load combinations.

14A.2.2 Members with Axial Forces

For tension only members, axial tension capacity is checked for the ultimate limit stress. Forcompression members, axial compression capacity is checked in addition to lateral bucklingand ultimate limit stress. The largest slenderness ratio (λ) shall not be greater than 250according to NS 11.7 Stability is checked as per the procedure of NS 12.3. The buckling curves ofNS fig. 3 have been incorporated into the STAAD.Pro code check. The coefficient α (as per NSTable 10) can be specified 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 NS table 11.

14A.2.3 Members with Axial Force and Bending Moments

For compression members with bending, interaction formulae of NS table 12.3.4.2 are checkedfor appropriate loading situation. All compression capacities are calculated per the procedure ofNS 12.3.

The equivalent moment factor β is calculated using the procedure of NS table 12. Two differentapproaches are used depending upon whether the members can sway or not. Conditions forsidesway and transverse loading can be specified through the use of parameters SSY and SSZ.


For members that cannot sway, without transverse loading, coefficients b are calculated andproper dimensioning moments are used in the interaction formulae.

14A.2.4 Lateral Buckling

Lateral torsional buckling is checked as per the procedure of NS 12.3.4. The procedure forcalculation of ideal buckling moment for sections with two axis of symmetry has beenimplemented. The coefficient can be provided by the user through the use of parameter CB.In the absence of CB, a value of 1.0 will be used. Torsional properties for cross sections(torsional constant and warping constant) are calculated using formulae from NS 3472. Thisresults in slightly conservative estimates of torsional parameters. The program willautomatically select the maximum moment in cases where Mvd is less than Mzd.

14A.2.5 Von Mises Yield Criterion

Combined effect of axial, bending, horizontal/vertical shear and torsional shear stress iscalculated at 13 sections on a member and up to 9 critical points at a section. The worst stressvalue is checked against yield stress divided by appropriate material factor. The von Misescalculates as:

= + + + + + ≤σ σ σ σ τ τ τ( ) ( )3j x by bz x y z

f

γ

2 2 y

m

14A.2.6 Material factor and nominal stresses

The design resistances are obtained by dividing the characteristic material strength by thematerial factor.

NS 3472

The material factor default value is 1.10. Other values may be input with the MF parameter.The nominal stresses should satisfy

≤ =σ fj

f

γ d

y

m

NPD

The general requirement is according to NPD 3.1.1. For stability the NPD 3.1.1 and 3.1.3 requiresthat the structural coefficient is considered.

≤ =⋅

S fd kd

f

γ γ S( )k

m mk d

Where:

Sd = reference stress or load effect resultant

fk = characteristic capacity

fkd = design capacity

γm = material coefficient

619— STAAD.Pro


γmk = structural coefficient

γm is default set to 1.10.

γmk shall be equal to 1.0 for frames. For pipe members γmk is a function of the reducedslenderness. In the STAAD.Pro implemented NPD code this is calculated automatically.

14A.2.7 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 local shellbuckling (NPD 3.2.2, 3.2.3).

c. Buckling of un-stiffened closed cylindrical shells, including interaction with overallcolumn 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 interaction formulaein NPD 3.2.2. The interaction between global and local buckling due to axial load andhydrostatic pressure is accounted for through computation of an axial characteristic capacity toreplace the yield stress inn the beam-column buckling formulae.

Note: Check b) handles members subjected to axial loads, bending moments andhydrostatic pressure. In other words, check b) assumes that stresses resulting fromshear and torsion are of minor importance, e.g., in jacket braces.

Check c) provides the unity check based on the stability requirement for un-stiffenedcylindrical shells subjected to axial compression or tension, bending, circumferentialcompression or tension, torsion or shear. The unity check refers to the interaction formulae inNPD 3.4.4.1. The stability requirement is given in NPD 3.4.7.

14A.2.8 Aluminum Check

STAAD.Pro performs a stability check on aluminum alloys according to buckling curve inECCS (European recommendation for aluminum ally structures 1978). It is possible to selectheat-treated or non heat-treated alloy from the parameter list in the 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 for non neat-treated. The yield check is the same as for steel.

14A.3 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure.


ParameterName

DefaultValue

Description Reference

CODE none Must be secified as either NS3472for NS or NPD for NPD (NOR mayalso be used for both).



BEAM 0.0 Parameter BEAM 1.0 ALL tells theprogram to calculate von Mises at13 sections along each member, andup to 8 points at each section.(Depending on what kind of shapeis used.)

Note: Must be set to 1.0

Sec. NS12.2.2

BY 1.0 Buckling length coefficient, β forweak axis buckling (y-y) (NOTE: BY> 0.0)

Fig. NS 3Sec. NS12.3

BZ 1.0 Buckling length coefficient, β, forstrong axis buckling (z-z) (NOTE:BZ > 0.0)

Fig. NS 3Sec. NS12.3

CB 1.0 Lateral buckling coefficient, Y. Usedto calculate the ideal bucklingmoments, Mvi

Sec. NS2A5.5.2 Fig.NS2A5.5.2a)-e)

CMY 1.0 Water depth in meters forhydrostatic pressure calculation forpipe members

Valid forthe NPDcode only

CMZ 0.49 αLT for sections in connection withlateral buckling

Sec. NS12.3.4 Fig.NS 6.

CY

CZ

Defaultsee NS3472

Buckling curve coefficient, a aboutlocal z-axis (strong axis). Representthe a, a0, b, c, d curve.

Fig. NS 3Sec. NS12.2 NSTable 11

Table 14A.1-Design Parameters for Norwegian Steel design code

621 — STAAD.Pro


ParameterName

DefaultValue


DMAX 100.0[cm]

Maximum allowable depth of steelsection.

DMIN 0.0 [cm] Minimum allowable depth of steelsection.

FYLD 235 Yield strength of steel, fy (St37)[N/mm2 ]

Tab. NS 3

MF 1.1(NS3472)

1.15(NPD)

Material factor / Resistance factor,γm

Sec. NS10.4.2 Sec.NPD 3.1


Sec. NS12.3.4.2

SSY 0.0 0.0 = No sidesway. β calculated. >0.0 = Sidesway in local y-axis weakaxis βM=SSY

Sec. NS12.3.4 Tab.NS 12 Sec.NPD3.2.1.4

SSZ 0.0 0.0 = No sidesway. β calculated. >0.0 = Sidesway in local y-axis weakaxis βM

Sec. NS12.3.4 Tab.NS 12 SecNPD3.2.1.4

TRACK 0.0 Controls the level of detail in theoutput:

0.0 = Suppress criticalmember stresses.

1.0 = Print all criticalmember stresses, i.e.,DESIGN VALUES

2.0 = Print von Misesstresses.

9.0 = Large output, 1page for eachmember.

See "- Tabulated Results" on page654 for complete list of availableTRACKs and print examples.


ParameterName

DefaultValue


UNL Memberlength

Effective length for lateral bucklingcalculations (specify bucklinglength). Distance between forksupports or between effective sidesupports for the beam

Sec. NS12.3

The parameter CMY will, when given with negative value, define an inside pressure in pipemembers. The pressure corresponds to given water depth in meters.

The parameter CB defines the φ value with respect to calculation of the ideal lateral bucklingmoment for single symmetric wide flange profiles, ref. NS app. 5.2.2.

14A.3.1 Example

Note: This is a partial example containing only the information pertaining to theNorwegian steel design code; used at the end of the input file.

* CODE CHECK ACCORDING TO NS3472

PARAMETERS

CODE NS3472

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 KNS METER

LOAD LIST 1

CHECK CODE MEMB 1

FINISH

14A.4 Stability Check According to NS 3472The stability check is based on the assumption that both ends of the member are structuralnodes. Buckling lengths and results for member with joints between the structural nodes

623— STAAD.Pro


have to be evaluated in each separate case.

Effects from local buckling or external hydrostatic pressure on pipes and tubes are notincluded.

The general stability criteria is: (ref. NS 12.3)

14A.4.1 Buckling

nmax + kz × mz + ky × my ≤ 1

14A.4.2 Lateral Buckling

+ + ≤k k m 1n

χ LTm

χ y yy

z

LT

Where:

i = z,y

nmax = n/χminn = Nf/Nd

χmin = min(χz,χy)

χi = Nkd,i/Nd

= − ≤k µ1 1.5i i

n

χ γi m

μi = λi(2·βMi - 4) ≤ 0.9

βMi ref. NS Tab. 12

= − ≤k µ1 1.0LT LT

n

χ γy m

μLT = 0.15(λy·βM - 1) ≤ 0.9

λi = λi/λ1λi = Lki/ii

=λ πiE

f y

=+ −

χi

ϕ ϕ λ

1

2 2

φ = 0.5[1 + α(λ - 0.2) + λ2]

α ref. NS Tab 10 & 11

=+ −

χLT

ϕ ϕ λ

1

LT LT LT2 2

= + − +

ϕ α λ λ( )0.5 1 0.4LT LT LT

2


α ref. NS sec. 12.3.4.1

=λLTW f

M

z z

cr

Mcr = ψ·Mvio

ψ ref. NS2 A5.5.2 Sect. a - d

= +M EI GI 1vio

π

Lz T

π

L

EC

GI

w

T

2

2

14A.4.3 Determination of βz and βyThe equivalent moment factor β (for z and y) is calculated dependant on momentdistributions as shown in the following table:

Moment diagram βM(βLT)

βM ψ = 1.8 - 0.7ψ

βM 0 = 1.3

βM 0 = 1.4

= + −β β β β( )M M ψ

M

M M M ψ, ∆ , 0 ,0

M0 = |Mmax| due to transverse loadonly

ΔM = |Mmax| if the moment has thesame sign

ΔM = |Mmax| + |Mmin| if the momentchanges sign

Table 14A.2-β for different moment distributions

The user can override the calculated factor with the following parameters:

625— STAAD.Pro


βy=SSY

βz=SSZ

14A.4.4 Lateral buckling

The Ideal lateral buckling moment is calculated according to NS2 A5.5.2

= = +M ψM ψL I I95 1vi vioE

L xπ

L

C

I

2.6 w

x

2

2

concern double symmetric cross sections where y is given in NS fig. A5.5.2, (input parameterCB), L = member length for lateral buckling (input parameter UNL), Cw and Ix , see section 5.

For single symmetric cross sections, the ideal lateral buckling moment is

= + − + −

+ −

M ϕ y C y( )vix

π EI

L

a

π

r

s

a

π

r

s

5

3

22 5

3

y x x

2

2 2 2

Where:

= +C

C L I

I

2 0.039w T

y

2

α = distance from profile CoG to point where the load is acting, assumed to beon top flange.

The φ parameter (ref NS fig. A5.5.2.g) is controlled by the input parameter CB.


Figure 14A.1 - ψ-coefficients for a simple span beam

627— STAAD.Pro


Figure 14A.2 - ψ-coefficients for a partially restrained beam


Figure 14A.3 - ψ-coefficients for a fully restrained beam

629— STAAD.Pro


Figure 14A.4 - ψ-coefficients for the cantilevered beam with single loads and distributed loads. Dashed curvesapply load on the surface.

14A.4.5 Stability check of pipe members

The stability criteria applied for members with pipe cross section is:

= +

+

≤

−

−

IR 1.0N

N

M

M

M

M1

2

1

2

kd

z

dN

NEzd

y

dN

NEyd

Where:

=

max ,N

N

N

N

N

Nkd kzd kyd

Mz and Mz are given in NS 5.4.2.

For the print output option TRACK 9.0 KE ≡ 1.0 and Mvd ≡ Md

14A.4.6 Angle profiles type RA (reverse angle)

The axial contribution to the total interaction ratio is checked according to the modifiedEECS-method, see NS A5.4.

The stability criterion is:


= + + ≤

−

−

IR 1.0N

N

M

M

M

M1 1kd

y

ydN

NEyd

z

zdN

NEzd

Where:

=

max ,N

N

N

N

N

Nkd kzd kyd

Nkyd and Nkzd are found from NS 3472 fig. 5.4.la C-curve for y- and z-axis, respectively.

For λ ≤ √(2)

λeff = 0.60 + 0.57λ

For λ > √(2)

λeff = λ

Where:

=λ λ

π

f

E

k y

λk = lk/i

=i I A/

Possible lateral buckling effects and torsional buckling (NS A5.4.5) is not included in thecode check. This has to be evaluated by the user separately.

14A.4.7 Stability check of members with tapered section

Stability of members with tapered cross section is calculated as described in section 3.1. Thecross section properties used in the formulae are calculated based on the average profileheight. (i.e., Iz, Iy values are taken from the middle of the member.)

14A.4.8 Lateral buckling for tension members

When compressive stress caused by large bending moment about strong axis is greater thantension stress from axial tension force, lateral buckling is considered as defined below.

σa = N/A (+ tension, - compression)

σbz = ± Mz/Wz

Mwarp = | σa + σb | Wz for σa + σb < 0 (compression)

IR = Mwarp/Mvd + My,max/Myd ≤ 1.0

14A.5 - Stability Check According to NPD

14A.5.1 Buckling of pipe members

Tubular beam-columns subjected to compression and lateral loading or end moments shallbe designed in accordance with NPD 3.2.2

631 — STAAD.Pro


+ + + ≤σ γ Bσ B σ B σ( )* ( )c mk b z bz y by

f

γ

2 2 y

m

Where:

σc = N/A = axial compressive stress

νmk = structural coefficient

B = bending amplification factor = 1/ (1 - μ), B is taken as the larger of Bz and ByBz = bending amplification factor about the Z-axis

By = bending amplification factor about the Y-axis

=µ σ f/c E

=f iE

π E

l

2

k

2

2

=i I A/

=

−

−

σ σ* 1 1b c

f

f

f

γ f

y

k

k

m E

lk = kl

k = effective length factor

fk = characteristic buckling capacity according to NS fig. 5.4.1a, curve A.

14A.5.2 Interaction with local buckling, NPD 3.2.3

If the below conditions are not satisfied, the yield strength will be replaced with characteristicbuckling stress given in NPD 3.4.

a. members subjected to axial compression and external pressure

≤ 0.5d

t

E

f y

b. members subjected to axial compression only

≤ 0.1d

t

E

f y

14A.5.3 Calculation of buckling resistance of cylinders

The characteristic buckling resistance is defined in accordance with NPD 3.4.4

=+

fk

f

λ1

y

4

Where:

=

+ + +

λf

σ

σ

f

σ

f

σ

f

τ

f

2 y

j

ao

ea

b

eb

p

ep eτ

0 0


= + − + + +σ σ σ σ σ σ σ τ( )( ) 3j a b a b p p2 2 2

σa ≥ 0 when

σa0 = 0

σa < 0 when

σa0 = -σaσb ≥ 0 when

σb0 = 0

σb < 0 when

σb0 = -σbσp ≥ 0 when

σp0 = 0

σp < 0 when

σp0 = σpσa = 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 = σΘ = 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, fep and feι are the elastic buckling resistances of curved panels or circularcylindrical shells subjected to axial compression forces, global bendingmoments, lateral pressure, and torsional moments and/or shear forcesrespectively.

14A.5.4 Elastic buckling resistance for un-stiffened, closedcylinders

The elastic buckling resistance for un-stiffened closed cylinders according to NPD 3.4.6 is:

=−

f k ( )e

π E

ν

t

l( )12 1

22

2

where k is a buckling coefficient dependent on loading condition, aspect ratio, curvature,boundary conditions, and geometrical imperfections. The buckling coefficient is:

= +k ψ ( )1pξ

ψ

2

The values of ψ, ζ, and p are given in Table 4.1 for the most important loading cases.

633— STAAD.Pro


ψ ζ p

Axial or Bending stress 1 0.702 Z +−

( )0.5 1r

t150

0.5

Torsion and shear force 5.34 0.856 Z0.75 0.6

Lateral pressure 4 1.04 Z0.5

Hyrdostatic pressure 2 1.04 Z0.5

Table 14A.3-Table 4.1 Buckling coefficients for un-stiffened cylindrical shells

The curvature parameter is defined by

= −Z ν1rt

1 22

For long shells the elastic buckling resistance against shear stresses is independent of shelllength. For cases with:

> 3.85r

r

t

1

the elastic buckling resistance may be taken as:

=f E( )0.25ep

t

r

2

14A.5.5 Stability requirements

The stability requirement for curved panels and un-stiffened cylindrical shells subjected toaxial compression or tension, bending, circumferential compression or tension, torsion or shearis given by NPD 3.4.7:

σj < fkdwhere the design buckling resistance is

=fkd

f

γ γ

k

m mk

14A.5.6 Column buckling, NPD 3.4.9

For long cylindrical shells it is possible that interaction between shell buckling and overallcolumn buckling may occur because second-order effects of axial compression alter the stressdistribution as compared to that calculated from linear theory. It is necessary to take thiseffect into account in the shell buckling analysis when the reduced slenderness of the cylinderas a column exceeds 0,2 according to NPD 3.4.4.1.

σbshall be increased by an additional compressive stress which may be taken as:

=

−

−

+

−

σ Bσ B σ∆ 1 1 1a

f

f

f

f by

k

k

e

Where:


=−

Bµ

1

1

=λ f f/y e

=fe

π E

λ

2

2

λ = slenderness of the cylinder as a column.

B, σa, σb, and μ are calculated in accordance with NPD 3.2.2.

14A.6 Yield CheckThe yield check is performed at member ends and at 11 equally spaced intermediate sectionsalong the member length.

At each section the following forces are applied:

Fx max. axial force along member

Fy actual shear in local y-direction at section

Fz actual shear in local z-direction at section

Mx max. torsional moment along member

My actual bending about local y-axis at section

Mz actual 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 stress point.

The stresses are calculated in several stress points at each member section. At each stress

point the von Mises stress is checked as follows:

= + − ⋅ + + + ≤σ σ σ σ σ τ τ τ( )3j o p o p x y z

f

γ

2 2 2 y

m

Where:

σtot = | σx + σby + σbz |

σp stress from hydrostatic pressure.

14A.6.1 Double symmetric wide flange profile

The von Mises stress is checked at four stress points as shown in figure below.

635— STAAD.Pro


Figure 14A.5 - Stress points checked for a wide flange section

Section Properties

Ax , Ix , Iy, and Iz are taken from STAAD.Pro database

Ay = h × s Applied in STAAD.Pro print option PRINT MEMBER STRESSES

Az = (2/3)· b · t · 2

τy = Fy/Ay

τz = Fz/Az

Ay and Az are not used in the code check

= −Cw

h t b t( )

24

2 3

ref. NS app. C3

Ty = dA × z

Tz = dA × y

Stress calculation

General stresses are calculated as:

= + + = + +σ σ σ σ z yx by bzF

A

M

I

M

I

x

x

y

y

z

z

= + + = + +τ τ τ τ cx y z

M

I

V T

I

V T

I

x

x

y z

z

z y

y

Where the component stresses are calculated as shown in the following table:


Point No σx

σby

σbz

τx

τy

τz

1

F

A

x

x

M

I

b

2

y

yM

I

b

2

z

z

tM

I

x

x

0 0

2 0F

I

bth

t2

y

z

2F

I

tb

t8

z

y

2

3 0 hM

I1

z

z

sM

I

x

x

F

I

bth

s

y

z

2 0

4 0 0+F

I

bth h s

s

( )0.5y

z

2 12

0

Table 14A.4-Stress calculations at selected stress points for a wide flangesection

In general wide flange profiles are not suitable for large torsional moments. The reportedtorsional stresses are indicative only. For members with major torsional stresses a separateevaluation has to be carried out. Actual torsional stress distribution is largely dependent onsurface curvature at stress point and warping resistance.

14A.6.2 Single symmetric wide flange profile and taperedsection

The von Mises stress is checked at nine stress points as shown in figure below.

Figure 14A.6 - Stress points checked for a singly symmetric wide flange section

Section properties

Ax, Ix , Iy, and Iz are taken from STAAD.Pro database, except for tapered sectionswhere these values are calculated for each section checked. (i.e., Iz, Iy values are

637— STAAD.Pro


taken from the middle of the member.)

= ⋅ + ⋅A b t b t2 / 3( )z 1 1

=⋅ − −

+Cw

b t b t h t t

b t b t( )( )/ 2 / 2

12

3131 1

2

3131 ref. NS app. C3

See "Double symmetric wide flange profile" on page 635 for equations used in section propertycalculations.

Stress calculation

See "Double symmetric wide flange profile" on page 635 for equations used in general stresscalculations.

Where the component stresses are calculated as shown in the following table:

PointNo

σx

σby

σbz

τx

τy

τz

1

F

A

x

x

−M

I

b

2

y

y

hM

I2

z

z

tM

I

x

x

0 0

2 0+F

I

bt h t

t

( )/ 22

y

z

1 F

I

tb

t8

z

y

2

3M

I

b

2

y

y0 0

4 0 hM

I1

z

z

sM

I

x

x

+F

I

bt h t

s

( )/ 2y

z

1 0

5 0 0+ +F

I

bt h t h s

s

( )/ 2 0.5y

z

1 12

0

6 0 − hM

I3

z

z

+F

I

b t h t

s

( )/ 2y

z

1 1 3 1 0

7 −M

I

b

2

y

y

1

− hM

I4

z

z

tM

I

x

x

0 0

8 0+F

I

b t h t

t

( )/ 22

y

z

1 1 3 1

1

F

I

t b

t8

z

y

1

2

1

9M

I

b

2

y

y

1 0 0

Table 14A.5-Stress calculations at selected stress points for a singlysymmetric wide flange section

In general wide flange profiles are not suitable for large torsional moments. The reportedtorsional stresses are indicative only. For members with major torsional stresses a separate


evaluation has to be carried out. Actual torsional stress distribution is largely dependent onsurface curvature at stress point and warping resistance.

14A.6.3 Pipe profile

The von Mises stress is checked in 3 stress points as shown in figure below.

Figure 14A.7 - Stress points for a pipe section

Section properties

d = D - 2t

r = 0.5 ( D-t )

a = tan-1Mz/My

Ax = π/4 (D2 - d2)

Ay = Az = 0.5AxIx = 2Iz =π/32 (D

4 - d4)

639— STAAD.Pro


Iy = Iz = π/64 (D4 - d4)

Note: In the STAAD.Pro analysis package slightly different values are usedfor Ay , Az and Ix , however this has insignificant influence on theforce distribution.

AY = Az = 0.6AxIx = 2πR

3t

Stress calculation at selected stress points

14A.6.4 Tube profile

Tube sections are rectangular or quadratic hollow uniform profiles. Critical stress is checked at5 locations as shown in figure below.


Section Properties

641 — STAAD.Pro



The general stress formulation is given in sec. 5.2.

14A.6.5 Channel profile

For channel profiles the von Mises stress is checked at 6 locations as shown in the figurebelow.


643— STAAD.Pro


Cross section properties

Stress calculations at selected stress points

The general stress formulation is given in sec. 5.2.f


14A.6.6 Angle profile type RA (reverse angle)

For angle profiles the von Mises check is checked at 8 stress points as shown in figure below.

Axes y and z are principal axes.

Axes u and w are local axes.

645— STAAD.Pro


Cross section properties

Section forces

The section forces from the STAAD.Pro analysis are about the principle axis y and z.

The second moment of area (Ty L TZ):

Ty = A Z

Tz = A Y



An additional torsional moment is calculated based on:

MT = Fy Z4

MT = Fz Y4

This torsion moment is included in Mx if Fy and FZ exist.

Beta-rotation of equal & unequal legged angles

Note: The order of the joint numbers in the member incidence command specifies thedirection of the local x-axis.

647— STAAD.Pro


14A.6.7 Rectangular massive box (prismatic)

Code check of the general purpose prismatic cross section defined in the STAAD.Pro analysispackage is not available. The prismatic section is assumed to be a rectangular massive box andthe von Mises stress is checked at 3 locations as shown in figure below.

Note: Note that ‘b’ may not be much greater than ‘h’. If that is the case, define themember with h > b and Beta angle 90° instead.

Section Properties

649— STAAD.Pro


General Stress Calculation

ref. [4] tab. 20, case 4 at midpoint the largest side i.e., point 2


14A.7 Tubular Joint Check, NPD 3.5For pipe members, punching shear capacity is checked in accordance with the NPD sections3.5.1 to 3.5.2, except 3.5.2.4. The chord is defined as the member with the greater diameter inthe joint. If the diameters are the same the program selects the member with the greaterthickness of the two. The chord members must be collinear by 5 degrees.

The punching shear run sequence is performed in two steps. The program will first identify alltubular joints and classify them as T type joints (TRACK99). The joints to be checked will belisted in a file specified in the CODE NPD parameter list, below called GEOM1. This file isused as input in the second run. The file is an editable ACSII file saved under the file namegiven in the CODE NPD parameter. The TRACK parameter is then set to 98 which directs theprogram to read from the file GEOM1 file and use it as input to the second run, i.e., the jointcapacity checking. 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 the joint itselfand the far end joints of the brace and chord, defined as in- and out-of plane moments.


The ASCII file should be edited to reflect the correct classification of the joints, gap, can orstub dimensions, yield stress and other geometric options if required. The program will notchange the brace or chord definition if this is changed or modified in 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

UNITS MM NEWTON

PARAMETER

CODE NPD GEOM1

FYLD 350 ALL

TRACK 99 ALL

BEAM 1.0 ALL

CHECK CODE ALL

14A.7.1 Static strength of tubular joints

The basic consideration is the chord strength. The required chord wall thickness shall be

determined when the other dimensions are given.

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-carryingbrace measured along chord outer surface

ß = r/R

g = R/T

651 — STAAD.Pro


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 chordstrength)

MOPk = Characteristic out-of-plane bending moment capacity of brace (asgoverned by the chord strength)

σax = Design axial stress in chord

σIP = Design in-plane bending stress in chord

σOP = Design out-of-plane bending stress in chord

This section gives design formulae for simple tubular joints without overlap and withoutgussets, diaphragms or stiffeners. Tubular joints in a space frame structure shall satisfy:

≤N N γ/k m

Where:

=N Q Qk u f

f T

sin Θ

y2

Qu is given in Table 6.1 and Qf is a factor to account for the nominal longitudinal stress in thechord.

Qf = 1.0 - 0.03γA2

= + +A

σ σ σ

f

2

0.64

ax IP OP

y

2 2 2

2


Type of joint andgeometry

Type of load in brace member

Axial In-planebending

Out-of-planebending

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)Qβ

Table 14A.6-Values for Qu

For β > 0.6, Qβ = 0.3/[β(1 - 0.833β)]

For β ≤ 0.6, Qβ = 1.0

For γ ≤ 20, Qg = 1.8 - 0.la/T

For γ > 20, Qg = 1.8 - 4g

but in no case shall Qg be taken as less than 1.0.

When β ≥ 0.9, Qf is set to 1.0. This is also applicable for moment loading. For cases withtension in the chord, Qf is set to 1.0. This is also applicable for moment loading.

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 determination ofeffective buckling length, and / or the structural coefficient γmk = 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 moment shall bedetermined by:

=M Q QIPk u f

d f T

sin Θ

y2

Where Qu is given in Table 6.1 and

Qf = 1.0 - 0.045γA2

The characteristic capacity of the brace subjected to out-of-plane bending moment shall bedetermined by:

=M Q QOPk u f

d f T

sin Θ

y2

Where Qu is given in Table 6.1 and

Qf = 1.0 - 0.021γA2

653— STAAD.Pro


For combined axial and bending loads in the brace, the following interaction equation shouldbe satisfied:

+

+ ≤N

N

M

M

M

M γ

21

k

IP

IPk

OP

OPk m

For overlapping tubular joints without gussets, diaphragms, or stiffeners, the total loadcomponent normal to the chord, NN, shall not exceed

= +N sin ΘNN

γ

l

l

f t l

γ

2

3

k

m

y w

m

1 2

where (see NPD fig. 3.10)

ll = circumference for that portion of the brace in contact with the chord (actuallength)

l = circumference of brace contact with chord, neglecting presence of overlap

Nk = characteristic axial load capacity of brace

tw = the lesser of the throat thickness of the overlapping weld or the thickness tof 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, wherecompression in a brace is essentially balanced by tension in brace(s) in the same side of thejoint.

14A.8 - Tabulated ResultsThis section presents a table with the various TRACKs available with respect to print out fromthe code check. Example prints and explanation to the information / heading given on theprint out is given in Appendix A.

TRACKno.

Description

0 Brief print of member utilizations (2 lines for each member)sorted with highest utilized members first

1 Based on TRACK 3 with additional information regardingstability factors and capacities

2 Simple print of stresses, including von Mises stress

3 Brief print of member utilizations (two lines for each member)

9 Comprehensive print with detailed information about memberand member utilization(one page for each member)

Table 14A.7-Available TRACK parameter values


TRACKno.

Description

99 Used in connection with tubular joint check according to NPD.This TRACK identifies tubular joints to be checked andclassifies all members entering the joint as T connection

98 Used in connection with tubular joint check according to NPD.This TRACK performs the joint capacity check

49 Prints member end forces for members entering each joint (atthe end of the member connected to the joint)

31 Prints maximum and minimum member end forces (axial forcedefines max and min) at member end 1

32 Prints maximum and minimum member end forces (axial forcedefines max and min) at member end 2

14A.8.1 Output for member design

Output example for TRACK 0.0

Symbol Description Unit

MEMB Member number kN

FXAxial force in the member (T = tension, C =compression)

kN-m

MYs Start moment about the y-axiskN-m

MYm Mid moment about the y-axiskN-m

MYe End moment about the y-axiskN-m

MYb Buckling moment about the y-axiskN-m

RATIO Interaction ratio

LOAD The critical load case number

TABLE Section type (HE, IPE, TUBE, etc.)

MZs Start moment about z-axiskN-m

655— STAAD.Pro



MZm Mid moment about the z-axiskN-m

MZe End moment about the z-axiskN-m

MZb Buckling moment about z-axiskN-m

COND Critical condition

DISTDistance from the start of the member to the criticalsection

m

Note: Myb and Mzb are the design moments used for max unity ratio.

NS3472 (VERSION 06002)UNITS ARE KN AND METE

MEMB FX MYs MYm MYe MYb RATIO LOADTABLE MZs MZm MZe MZb COND DIST

===============================================================================1 12.80 C 0.0 0.0 0.0 0.0 5.08 1FAIL PIPS40 (AISC SECTIONS)

31.9 -15.9 -36.2 36.2 STAB 10.004 24.20 C 0.0 0.0 0.0 0.0 1.30 1FAIL PIPS40 (AISC SECTIONS)

-0.2 -1.4 -2.9 2.9 STAB 14.143 26.31 C 0.0 0.0 0.0 0.0 0.78 1

PIPS40 (AISC SECTIONS)5.1 1.3 2.5 5.1 STAB 0.00

2 4.02 C 0.0 0.0 0.0 0.0 0.58 1PIPD60 (AISC SECTIONS)

36.4 -38.1 -6.8 38.9 STAB 5.835 5.02 T 0.0 0.0 0.0 0.0 0.34 1

PIPS40 (AISC SECTIONS)3.6 -1.8 1.7 2.8 VMIS 0.00



CURVE St Buckling curve about the strong axis

CURVE Wk Buckling curve about the weak axis

Beta Z Buckling length factor about z-axis



Beta Y Buckling length factor about y-axis

FYLD Allowable yield strength N/mm2

Betamz Equivalent moment factor βm about z-axis

Betamy Equivalent moment factor βm about y-axis

Fak Z Factor k according to 12.3.4.2 about the z-axis

Fak Y Factor k according to 12.3.4.2 about the y-axis

MYD Moment capacity about the y axis kN-m

MZD Moment capacity about the z axis kN-m

MVD Lateral buckling moment kN-m

IR1Interaction ratio for buckling without lateralbuckling (Cl. 12.3.4.2)

IR2Interaction ratio for buckling with lateralbuckling (Cl. 12.3.4.2)

VON MISES Interaction ratio for von Mises

NS3472 (VERSION 06002)UNITS ARE KN AND METE

MEMB FX MYs MYm MYe MYb RATIO LOADTABLE MZs MZm MZe MZb COND DIST

==============================================================================-=

1 12.80 C 0.0 0.0 0.0 0.0 5.08 1FAIL PIPS40 (AISC SECTIONS)

31.9 -15.9 -36.2 36.2 STAB 10.00|-------------------------------------------------------------------------|| CURVE St A Wk A Beta Z 1.00 Beta Y 1.00 FYLD= 235. N/MM2 || Betamz=1.295 Betamy=1.000 FakZ=1.500 FakY=1.500 || MYD =.112E+2 KNM MZD =.112E+2 KNM MVD =.112E+2 KNM || IR1 = 5.076 IR2 = 5.076 VON MISES = 3.251 ||-------------------------------------------------------------------------|

2 4.02 C 0.0 0.0 0.0 0.0 0.58 1PIPD60 (AISC SECTIONS)

36.4 -38.1 -6.8 38.9 STAB 5.83|-------------------------------------------------------------------------|| CURVE St A Wk A Beta Z 1.00 Beta Y 1.00 FYLD= 235. N/MM2 || Betamz=1.377 Betamy=1.000 FakZ=1.021 FakY=1.033 || MYD =.701E+2 KNM MZD =.701E+2 KNM MVD =.701E+2 KNM || IR1 = 0.575 IR2 = 0.575 VON MISES = 0.557 ||-------------------------------------------------------------------------|

3 26.31 C 0.0 0.0 0.0 0.0 0.78 1PIPS40 (AISC SECTIONS)

657— STAAD.Pro


5.1 1.3 2.5 5.1 STAB 0.00|-------------------------------------------------------------------------|| CURVE St A Wk A Beta Z 1.00 Beta Y 1.00 FYLD= 235. N/MM2 || Betamz=2.152 Betamy=1.000 FakZ=0.602 FakY=1.500 || MYD =.112E+2 KNM MZD =.112E+2 KNM MVD =.112E+2 KNM || IR1 = 0.784 IR2 = 0.784 VON MISES = 0.510 ||-------------------------------------------------------------------------|

4 24.20 C 0.0 0.0 0.0 0.0 1.30 1FAIL PIPS40 (AISC SECTIONS)

-0.2 -1.4 -2.9 2.9 STAB 14.14|-------------------------------------------------------------------------|| CURVE St A Wk A Beta Z 1.00 Beta Y 1.00 FYLD= 235. N/MM2 || Betamz=1.510 Betamy=1.000 FakZ=1.500 FakY=1.500 || MYD =.112E+2 KNM MZD =.112E+2 KNM MVD =.112E+2 KNM || IR1 = 1.304 IR2 = 1.304 VON MISES = 0.310 ||-------------------------------------------------------------------------|



659— STAAD.Pro


Output example for TRACK 3


Member in tension:


Member in compression:

661 — STAAD.Pro


Member in compression (pipe - NPD):

663— STAAD.Pro


14A.8.2 Tracks for joint capacity code checking


665— STAAD.Pro


14A.8.3 Special prints (not code check)



667— STAAD.Pro


669— STAAD.Pro

14B. Norwegian Codes - Steel Design per NORSOK N-004STAAD.Pro is capable of performing steel design based on the Norwegian code NORSOK N-004 Rev 2, October 2004. Code checks for tubular (pipe) members is performed per the code.

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.

Design of members per NTC 1987 requires the STAAD N. Eurozone Design CodesSELECT Code Pack.

14B.1 Member ResistancesThe implementation of the NORSOK N-004 code in STAAD.Pro considers sections 4, 5, 6 & 7in of that document. The details of the various clauses implemented from these sections ispresented here for member checking and design.

14B.1.1 General Provisions

The general safety check is per Section 4. Checks are made to ensure that the design actioneffect (Sd) is less than or equal to the design resistance (Rd):

Sd ≤ RdThe design resistance is evaluated for each condition and this check is applied as described inthe following sections.

14B.1.2 Steel selection and non destructive testing

Section 5 deals with the choice of “design class” for structural joints and components. Thechoice of design class will determine the choice of steel grade & quality and also thedetermination of inspection category for fatigue. The choice of design class (as per Table 5-1 ofthe code) is left to you and does not have any direct impact on how STAAD.Pro performsdesign checks.

14B.1.3 Ultimate Limit States

Clause 6.1 primarily deals with the section of material factors to be used in the variousconditions or checks. The material factors chosen are dependent on the ‘section class’ of a crosssection. N-004 does not explicitly specify how to classify various cross sections. Therefore, thesection classification is made as given in Section 5.5 of EN 1993-1-1:2005, except when specifiedexplicitly along with member checks (See Member Subject to Axial Compression).

Also, N-004 does not specify steel grades to be used. Therefore, this STAAD.Pro uses the steelgrades 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 this implementation.


14B.1.4 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 in STAAD.Pro. Awarning 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 warning will beissued 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’ to define out ofplane effects. This is the opposite to what STAAD uses, where ‘Z’ defines the inplane effects and ‘Y’ the out of plane effects. This document will follow theSTAAD.Pro convention for the Z and Y axes.

The N-004 code also segregates members into those that are subject to hydrostatic pressureand those that are not subject to hydrostatic pressure. The program allows you to specifywhether a member is subject to hydrostatic pressure or not and, if so, to specify thehydrostatic pressure for the element. By default the program will assume that all members arenot subject to any hydrostatic pressure. The design parameter HYD is used to specify themaximum water level with respect to the origin.

If the HYD parameter is specified, the program will take that to be the water level and willevaluate the pressure distribution on each element assuming a linear increase in pressurewith depth (The density of water is assumed to be 9.8 KN/m3). Also, if the HYD parameter isspecified, the program will assume that the hydrostatic loads have not been included in theanalysis. For members that are subject to a combination of loads (i.e., bending pluscompression) along with a hydrostatic pressure, the design will be done according to Clause6.3.9 of the code. In the absence of any hydrostatic pressure on the member the design will beperformed in accordance with Clause 6.3.8 of the code.

14B.2 .1 Ultimate Limit State

14B.3 Axial TensionClause 6.3.2 states that tubular members subject to axial tension shall satisfy the followingcondition:

671 — STAAD.Pro

14B. Norwegian Codes - Steel Design per NORSOK N-004

NSd ≤ Nt,Rd = A⋅fy/γmWhere:

NSd = Design axial force (tension positive)

fy = Characteristic yield strength

A = Cross section area

γm = Default material factor = 1.15

14B.4 Axial CompressionClause 6.3.3 states that tubular members subject to axial compression shall satisfy the followingcondition:

NSd ≤ Nc,Rd = A⋅fc/γmWhere:

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 any hydrostaticpressure will be taken as the smaller of in plane or out of plane buckling strengths determinedby the equations given below:

fc = [1.0 - 028⋅λ2]fy when λ ≤ 1.34

fc = 0.9/λ2⋅fy when λ > 1.34

λ = √(fcl/fE) = k⋅l/(π⋅i)√(fcl/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 = fy when fy/fcle ≤ 0.170 (Plastic yielding)

fcl = [1.047 - 0.274⋅fy/fcle]⋅fy when 0.170 < fy/fcle ≤ 1.911 (Elastic/Plastic)


fcl = fcle when fy/fcle > 1.911 (Elastic buckling)

Where:

fcle = 2CeE⋅t/D (Characteristic elastic local buckling strength)

Ce = 0.3 (Critical elastic buckling coefficient)

D = Outside diameter

t = wall thickness

For a member that is subject to pure compression, if fy/fcle > 0.170, the section will be classedas a CLASS 4 (slender section). In such cases, the value of the material factor (γm) used in theabove checks is increased according to equation 6.22 (Cl. 6.3.7) of the code.

14B.5 BendingClause 6.3.4 states that tubular members subject to pure bending alone shall satisfy:

MSd ≤ MRd = fm⋅W/γmWhere:

MSd = Design bending moment

fm = Characteristic bending strength

W = Elastic section modulus


The bending strength fm is calculated as:

fm = Z/W⋅fy when fyD/(E⋅t) ≤ 0.0517

fm = [1.13 - 2.58⋅fyD/(E⋅t)]⋅Z/W⋅fy when 0.0517 < fyD/(E⋅t) ≤ 0.1034

fm = [0.94 - 0.76⋅fyD/(E⋅t)]⋅Z/W⋅fy when 0.1034 < fyD/(E⋅t) ≤ 120⋅fy/E

14B.6 ShearClause 6.3.5 states that tubular members subject to shear shall satisfy:

VSd ≤ VRd = A⋅fy/(2√3⋅γm))

Where:

VSd = Design shear force

fy = Yield strength

A = Cross section area

γm = Default material factor = 1.15

When torsional shear stresses are present, the following condition shall also be satisfied:

673— STAAD.Pro


MT,Sd ≤ MT,Rd = 2⋅Ipfy/(D√3⋅γm))

Where:

MT,Sd = Design bending moment

Ip = Polar moment of inertia

14B.7 Hydrostatic PressureClause 6.3.6 states that tubular members subject to an external pressure shall primarily bechecked for hoop buckling. The condition to be satisfied is:

σp,Sd ≤ fh,Rd = fh/γm)Where:

σp,Sd = pSd⋅D/(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 = fy when fhe > 2.44⋅fyfh = 0.7⋅fy(fhe/fy)

0.4 when 2.44⋅fy ≥ fhe > 0.55⋅fyfh = fhe when fhe ≤ 0.55⋅fy

The elastic hoop buckling strength fhe will be worked out as follows:

fhe = 2ChE⋅t/D

Where:

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, or endconnections.

14B.8 Combined Axial Tension and Bending (withoutHydrostatic Pressure)Clause 6.3.8.1 states that tubular members subject to axial tension and bending shall bedesigned 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)

NSd is the design axial force

MRd is the moment resistance (as determined by Clause 6.3.4)

Nt,Rd is the tension capacity of the section (as determined by Clause 6.3.2)

14B.9 Combined Axial Compression and Bending (withoutHydrostatic Pressure)Clause 6.3.8.2 states that tubular members subject to axial tension and bending shall bedesigned to satisfy the following conditions:

and

Where:

NSd is the design axial compression

Cmy and Cmz are the reduction factors corresponding to the Y and Z axesrespectively. You may specify a value for these using the CMY and CMZ designparameters, respectively (default is 0.85 for both).

Ney and Nez are the Euler buckling loads about y & z axes and are given by:

675— STAAD.Pro


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:

fcl is 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 beas given in Table 6-2 of N-004. This requires the member to be classified under any one of thesection types given in the table.

14B.10 Combined Bending and Shear (withoutHydrostatic Pressure)Clauses 6.3.8.3 & 6.3.8.4 state that tubular members subject to beam shear force (excludingshear due to torsion) and bending moments shall satisfy:

MSd/MRd ≤ √(1.4 - VSd/VRd) when VSd/VRd≥ 0.4

MSd/MRd ≤ 1.0 when VSd/VRd< 0.4

If the member is subject to shear forces due to torsion along with bending moments, thecondition to be satisfied is:

MSd/MRed,Rd ≤ √(1.4 - VSd/VRd) when VSd/VRd≥ 0.4

MSd/MRed,Rd ≤ 1.0 when VSd/VRd< 0.4

Where:

MRed,Rd = W⋅fm,Red/γmfm,Red = fm√[1 - 3(τT,Sd/fd)

2]

τT,Sd = MT,Sd/(2π⋅R2⋅t)

fd = fy/γmR = Radius of the tubular member


14B.11 Combined Loads with Hydrostatic PressureClause 6.3.9 of NS-004 describes two methods to check for members subject to combinedforces in the presence of hydrostatic pressure: depending on whether the hydrostatic forceswere included as nodal forces in the analysis or not. If the hydrostatic forces have not beenincluded in the analysis as nodal forces, Method A given in the code is used. If, however, thehydrostatic forces have been included in the analysis, then Method B in the code is used. Priorto proceeding with the checks described in the sections below, the section is verified for hoopstress limit per clause 6.3.6 (see Hydrostatic Pressure above).


The choice of method for checking members subject to combined forces and hydrostaticpressure used by STAAD.Pro will depend on the HYD parameter specified as a designparameter. If the HYD parameter has been specified, then the program will assume that thehydrostatic forces have not been included in the analysis and will perform the necessarychecks as per Method A in code. If, on the other hand, the HYD parameter has not beenspecified, the program will use the section forces and use Method B in the code.

14B.12 Combined Axial Tension, Bending, andHydrostatic PressureChecks 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 axial compressionfrom hydrostatic pressure.

σq,Sd is the design axial compressive stress due to hydrostaticpressure. (i.e., the axial load arising from the hydrostatic pressurebeing 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,Rdη = 5 - 4⋅fh/fy

b. For the net axial compression condition (σa,Sd < σq,Sd)

Where:

fcl,Rd = fcl/γm

677— STAAD.Pro


fcl is the characteristic local buckling strength (as determined byClause 6.3.3)

Additionally, when:

σc,Sd > 0.5⋅fhe/γmand

fcle > 0.5⋅fhethe following condition shall be satisfied in addition to the above check(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

14B.13 Combined Axial Compression, Bending, andHydrostatic PressureChecks per Clause 6.3.9.2:

A. Method used when HYD has been specified:


and


Where:

σa,Sd is the design axial stress that excludes the stress from hydrostaticpressure

Additionally, when:


fcle > 0.5⋅fhethe following condition shall be satisfied in addition to the above check(s):

B. Method used when HYD has not been specified:


a. For the net axial tension condition (σac,Sd ≥ σq,Sd)

and

679— STAAD.Pro


(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:


fcle/γm > 0.5⋅fhe/γmthe following condition shall be satisfied in addition to the above check(s):

Where:

σc,Sd is the maximum compressive stress at that section.

14B.14 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure.

ParameterName

DefaultValue

Description

CODE none Must be specified as NORSOK.

Note: Do not use the shortened NOR, asthis initiates an NS3472 design.

Table 14B.1-Design Parameters for NORSOK N-004 design code


ParameterName

DefaultValue

Description

FYLD 235 [MPa] Yield strength of steel, fy (St37)

Note: Note, if the SGR value is specified,then the associated value of fy forthat steel grade will be used for amember in lieu of the 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 slenderness valueKL/r

LZ MemberLength

Length in local Z axis for slenderness valueKL/r

CMY 0.85 Reduction factor Cm corresponding to the Yaxis.

CMZ 0.85 Reduction factor Cm corresponding to the Zaxis.

LSR Length of Tubular between Stiffening Rings.This value is required to calculate DesignHoop Stress due to Hydrostatic Pressure tocheck Hoop Buckling as per clause 6.3.6.1.

HYD 0.0 The Y-coordinate, current units, of themaximum water level with respect to theorigin.

Note: If SET Z UP command has beenspecified, then yi will be the Z co-ordinate of the max water level.

For HYD > 0, the value of max. hydrostaticpressure calculated is reported for eachmember in a TRACK 2.0 output.

PSD 0.0 Water pressure at each section in absence ofHYD.

681 — STAAD.Pro


ParameterName

DefaultValue

Description

SGR 0.0 Steel Grade per EC3 (EN 1993-1-1:2005):

0.0 = S 235 grade steel





DMAX 100.0 [cm] Maximum allowable depth of steel section.

DMIN 0.0 [cm] Minimum allowable depth of steel section.

DFF None(Mandatory

for deflectioncheck)

"Deflection length"/maximum allowable localdeflection.

MAIN 0.0 Option to design for slenderness.

0.0 = Check for slenderness

1.0 = Do not check forslenderness

Any value greater than 1.0 isused as the limit for slendernessin compression.

TMAIN 180.0 Slenderness limit in tension. Slenderness limitis checked based the MAIN parameter.

TRACK 0.0 Output detail:

0.0 = Only a summary of thedesign checks performed isprinted.

2.0 = All the details of themember checks and the variousclause checks performed areprinted.



ParameterName

DefaultValue

Description

BEAM 0.0 Beam segment locations for design:

0.0 = design only for endmoments and those at locationsspecified by SECTION command.

1.0 = Perform design formoments at twelfth pointsalong the beam.


Joint No. denoting start point for calculationof “deflection length”

DJ2 End Jointof member

Joint No. denoting end point for calculationof “deflection length”

14B.14.1 Notes

a. C1 and C2 Parameters

The default values of these coefficients are taken from Table 6-4 of N-004 and dependon 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 loading 25 30

Table 14B.2-Default values for C1 and C2 parameters

Note: These values can be changed by setting the K, X, and Y values in theexternal geometry file.

14B.14.2 Example

Note: This is a partial example containing only the information pertaining to theNORSOK N-004 steel design code; used at the end of the input file.

* CHECK TUBULAR MEMBERS ACCORDING NORSOK N-004

CODE NORSOK

HYD 3.0 MEMB 1 TO 3

683— STAAD.Pro


PSD 10 MEMB 7 10

SGR 2 MEMB 1 TO 3 7 10

TRACK 2 MEMB 1 TO 3 7 10

CHECK CODE MEMB 1 TO 3 7 10

14B.15 Code CheckingThe purpose of code checking is to ascertain whether the provided section properties of themembers are adequate as per N-004. Code checking is done using the forces and moments atspecific sections of the members. If no sections are specified, the program uses the start andend forces for code checking.

When code checking is selected, the program calculates and prints whether the members havepassed or failed the checks, the critical condition of NORSOK code, the value of the ratio ofthe critical condition (overstressed for value more than 1.0 or any other specified RATIO value),the governing load case, and the location (distance from the start of the number of forces inthe member) where the critical condition occurs.

14B.16 Member SelectionSTAAD is capable of performing design operations on specified members. Once an analysis hasbeen performed, the program can select the most economical section (i.e., the lightest sectionwhich fulfills the code requirements for the specified member). The section selected will be ofthe same type section as originally designated for the member being designed. Memberselection can also be constrained by the parameters DMAX and DMIN which limit the maximumand minimum depth of the members.

Selection of members whose properties are originally input from a user created table will belimited to sections in the user table.

14B.17 Tubular Joint CheckingThe design of tubular joints for this implementation shall be based on section 6.4 of N-004and will be applicable to joints formed from a connection of two or more members.


Figure 14B.1 - Typical Tubular Joint (Fig 6-1 in N004)

Prior to completing a joint design, the joint should be classified into one of the threecategories given by the code. Joint classification is the process whereby a BRACE memberconnecting into a CHORD member is classified into one of these categories based on the axialforce components in the brace. The classification normally considers all the members at ajoint that lie in a plane. N-004 defines three joint classification categories: K, X, or Y (or acombination of these).

JointClassification

Description

K The axial force in the brace should bebalanced by forces in the other bracesin the same plane and on the sameside of the joint. The code allows a10% tolerance in the balancing force.

X The axial force in the brace is reactedas a beam shear in the chord.

Y The axial force in the brace is carriedthrough the chord to braces in theopposite side.

Note: Typical examples of these joint types are given in Figure 6-3 of the N-004 code. It isworth noting that the joint class for each brace will be different for each load case.

Note: STAAD.Pro does not perform an automatic classification of the joints. This is leftup to the engineer. All joints will initially be classified as Y in the generation of

685— STAAD.Pro


the external geometry file. Joints should be re-classified as necessary beforeperforming 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.Pro performs thechecks as per these clauses. However, the program does not deal with conical joint transitionsand joints with joint cans. The code also specifies checks and limits for the gaps andeccentricity of joints. This implementation will not perform such geometry checks.

The details of the checks done and the methodology will be discussed in the followingsections.

14B.17.1 Identification and Classification of CHORD andBRACE Members

This is a two step process where the program automatically identifies the CHORD and BRACEmembers at a joint and perform a default joint check. The input variables used for the initialjoint checks will be generated in an external text file. You can then use this text file to edit ormodify the input variables and perform a final 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 ALL keywordoption will cause the program to perform the joint check at all the nodes.

For each node specified in the CHECK JOINT command, the program automatically separatesout all the members at the node into one CHORD member and one or more BRACE members.The section with the biggest diameter is assumed to be the CHORD and all the othermembers are assumed as BRACE members. If two or more possible CHORD members have thesame diameter, the member with the maximum thickness is considered as the CHORD. Theangle between the two members should be within the range of 30° and 90° (inclusive).

Once all the CHORD and BRACE members are identified, the program considers everyCHORD to BRACE connection as a separate JOINT. The program the automatically creates thejoints and initially considers all the joints as joint class Y. The program then performs all thenecessary joint checks as detailed in the following sections and produces the design output.The program will also produce an output file called filename_ JOINTS.txt, where "filename"will be the name of the .STD file. This format of this text file is explained in Section 14B.8.

You can then edit this text file to set up the necessary design parameters. Once the programfinds of the _JOINTS.txt file, it will read in the necessary parameters from this file andperform the subsequent design checks.


Note: This file will be produced only once (i.e., when this file does not exist). If this fileexists, it is assumed that you have already done a joint design check and hence theprogram reads the values from this file and uses these for joint checks.

14B.18 Tubular Joint Resistance

14B.18.1 Basic Joint Resistances

The characteristic joint resistance between a chord and a brace is given by:

=N Q QRd

f T

γ θ u fsin

y

M

2

=M Q QRd

f T d

γ θ u fsin

y

M

2

Where:

NRd is the joint design axial resistance

MRd is the joint design bending moment resistance.

fy is 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 thebrace. Refer to Table 6-3 and Clause 6.4.3.3 of N-004 for these equations.

Qf = 1.0 – λA2

=

+

+A C C

σ

f

σ σ

f

21

2

21.62

a Sd

y

my Sd mz Sd

y

, ,2

,2

2

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 the jointresistance. C2 is the coefficient used for the bending stress term in calculatingthe joint resistance. The default values of C1 and C2 are as given in Table 6-4 ofN-004. The actual values used are dependent on the values of K, X, and Yspecified for the joint in the external geometry file.

See also Figures 6-3 to 6-6 of N-004 for definition of the various terms forvarious joint classes.

14B.18.2 Strength Check for Joints

Each brace to chord joint to be checked will have to satisfy the following condition:

687— STAAD.Pro


+

+ ≤ 1N

N

M

M

M

M

2

Sd

Rd

z Sd

z Rd

y Sd

y Rd

,

,

,

,

Where:

NSd is the design axial force in the brace,

NRd is 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

14B.19 External Geometry FileThe data contained in the filename_JOINTS.NGo file should meet the following format. Theoverall process of performing punching shear checks consists of two steps which are explainedin Section 14B.7.

14B.19.1 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

n# = the node number

K%, X%, and Y% = The fractional contributions of K-type, X type and Y-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 valueof GAP is assumed as 0.


14B.19.2 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 6.0430.075 0.005 0

14B.20 Tabulated ResultsFor code checking or member selection, the program produces the results in a tabulatedfashion. The items in the output table are explained as follows:

Memberthe member number for which the design is performed.

TABLEthe steel section name which has been checked against the N-004 code or has beenselected.

RESULTSprints whether the member has PASSed or FAILed. If the RESULT is FAIL, therewill be an asterisk (*) mark on front of the member.

CRITICAL CONDthe section of the N-004 code which governs the design.

RATIOprints the ratio of the actual stresses to allowable stresses for the critical condition. Normally a value of 1.0 or less will mean the member has passed.

LOADINGthe load case number which governed the design.

FX, MY, and MZprovide the axial force, moment in local Y-axis, and the moment in local Z-axisrespectively. Although STAAD does consider all the member forces and moments(except torsion) to perform design, only FX, MY and MZ are printed since they arethe ones which are of interest, in most cases.


Note: If the parameter TRACK is set to 2.0, the program will block out part of the tableand will print the allowable bending stressed in compression (FCY & FCZ) andtension (FTY & FTZ), allowable axial stress in compression (FA), and allowableshear stress (FV).

14B.20.1 Sample TRACK 2.0 OutputSTAAD.PRO CODE CHECKING - NORSOK-N004 (V1.0)

689— STAAD.Pro


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



=======================================================================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 : 168.554 168.554Elastic 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


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

691 — STAAD.Pro


14C. Norwegian Codes - Concrete Design per NS 3473STAAD.Pro is capable of performing concrete design based on the Norwegian code NS 34732001 Concrete Structures - Design and detailing rules.

Design of members per NS 3473 requires the STAAD N. Eurozone Design Codes SELECT CodePack.

14C.1 Design ParametersDesign parameters communicate specific design decisions to the program. They are set todefault values to begin with and may be altered to suite the particular structure.

ParameterName

DefaultValue

Description

CODE none Must be specified as NS3473



ACTAGE 70 years Enter the actual age, in years.

BRACE 0 Column Brace Parameter

0. Beam/ Column braced in both directions.

1. One-way plate/ Column unbraced aboutthe local z axis only.

2. Column unbraced about the local y axisonly.

3. Column unbraced in both directions.

CLEAR 25 mm Clear cover to outermost reinforcing bar.

DRYCIR 100% Drying exposure, in percent.

EFACE 0 Distance from the end node of the beam to face ofsupport for shear design.

ELY 1 Member length factor about the local y direction.

ELZ 1 Member length factor about the local z direction

Table 14C.1-Design Parameters for NS 3473 design code


ParameterName

DefaultValue

Description





FC 35N/mm2

Compressive strength of concrete.

FYMAIN 500N/mm2

Yield strength of main reinforcing steel.


MAXMAIN

32 Maximum size permitted for main reinforcementbar.

MINMAIN 10 Minimum size permitted for main reinforcementbar.

MOY moy factor

MOZ moz factor

NMAG nmag factor


RELHUM 70% Relative humidity, in percent.



2. Two faced distribution about minor axis.

3. Two faced distribution about major axis.


SFACE 0 Distance from the start node of the beam to faceof support for shear design.




693— STAAD.Pro

14C. Norwegian Codes - Concrete Design per NS 3473

ParameterName

DefaultValue

Description


10. Beam — Ultimate limit state and Servicelimit state design & Slab — Two-way platedesign

11. Beam — Ultimate limit state and Servicelimit state design with tension stiffening.

12. Beam — Ultimate limit state design only




695— STAAD.Pro

Section 15

Russian Codes


697— STAAD.Pro

15A. Russian Codes - Concrete Design Per SNiP 2.03.01-84*

STAAD.Pro is capable of performing concrete design based on the Russian code СНиП 2.03.01-84*: СТРОИТЕЛЬНЫЕ НОРМЫ И ПРАВИЛА БЕТОННЫЕ И ЖЕЛЕЗОБЕТОННЫЕКОНСТРУКЦИИ (SNiP 2.03.01-84* Building Regulations: Concrete and Reinforced ConcreteConstruction).

Design of members per SNiP 2.03.01-84* requires the STAAD E. Eurozone Design CodesSELECT Code Pack.

15A.1 GeneralRussian Code SNiP 2.03.01–84* plain concrete and concrete structures is based on the methodof limit states. Code SNiP 2.03.01–84* defines two groups of limit states.

Analysis according to the first group of limit states is performed to avoid the followingphenomena:

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 environmental effects.

Analysis according to the second group of limit states is performed to avoid the followingphenomena:

l excessive and long-term opening of cracks if they are allowed according to serviceconditions,

l excessive displacements.

Analysis of structures for the first group of limit states is performed with the use of themaximum (design) loads and actions. Analysis of structures for the second group of limitstates is made in accordance with the operational (normative) loads and actions. Ratiobetween design and normative loads is called reliability coefficient for loads which isdetermined according to SNiP 2.01.07.-85 “Loads and actions”.

Reliability coefficient γn for destination according to SNiP 2.01.07.-85 shall be considered indetermination of loads and their combinations.

Program STAAD.Pro makes it possible to calculate reinforcement for concrete membersaccording to codes of many countries round the World and Russian Code SNiP 2.03.01-84*inclusive. Algorithms for calculation of reinforcement of concrete linear (beams, columns) and2D (two dimensional) (slabs, walls, shells) members are incorporated in program STAAD.Pro.Not only Code SNiP 2.03.01-84* but also the “Guide for design of plain concrete and reinforcedconcrete structures from normal weight and lightweight concrete (to SNiP 2.03.01-84)” havebeen used in creation of these algorithms.


It is possible using program STAAD.Pro to calculate reinforcement for beams of rectangularor T section and for columns of rectangular or circular section (Fig.1).

Figure 15A.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 angle BETA=0°,or at the bottom zone of the section, if BETA=180°.

15A.2 Design Parameters and Input DataEntry of data of cross-sections of beams and columns is made by the use of MEMBERPROPERTIES command, and thicknesses of 2D members are entered by ELEMENTPROPERTY command.

Example:

UNIT MM

MEMBER PROPERTIES

* COLUMNS OF RECTANGULAR CROSS-SECTION

1 TO 16 PRI YD 350. ZD 350.

* COLUMNS OF CIRCULAR CROSS-SECTION

17 TO 22 PRI YD 350.

* BEAMS OF T CROSS-SECTION

23 TO 40 PRI YD 450. ZD 550. YB 230. ZB 200.

UNIT METER

ELEMENT PROPERTY

41 TO 100 THICKNESS 0.14

101 TO 252 THICKNESS 0.16

* FLANGE OF T BEAMS IS LOCATED AT THE BOTTOM ZONE OF CROSS-SECTION

BETA 180. MEMB 23 TO 40

COMMANDS FOR CALCULATION OF REINFORCEMENT ARE LOCATED IN THEINPUT DATA FILE AFTER THE COMMAND OF ANALYSIS AND AS A RULE,AFTER OUTPUT COMMANDS TO PRINT RESULTS OF CALCULATION.

Example:

* COMMAND OF ANALYSIS

PERFORM ANALYSIS

699— STAAD.Pro


.

.* OUTPUT COMMAND TO PRINT RESULTS OF CALCULATION (ACCORDING TOUSER’S JUDGMENT)

.

* COMMAND OF LOADING AND THEIR COMBINATIONS CONSIDERED IN DESIGN

LOAD LIST 1 5 TO 9

* COMMAND TO START REINFORCEMENT CALCULATION PROCEDURE


CODE RUSSIAN

.* LIST OF PARAMETERS BEING USED IN REINFORCEMENT CALCULATION

.

.

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

.

.

.

* COMMAND OF BEAM REINFORCEMENT CALCULATION

DESIGN BEAM 23 TO 40

* COMMAND OF COLUMN REINFORCEMENT CALCULATION


* COMMAND OF CALCULATION 2D ELEMENTS (SLABS, WALLS, SHELLS)


* COMMAND OF INTERRUPTION REINFORCEMENT CALCULATION

END CONCRETE DESIGN

In tables 1, 2 and 3 information about parameters used for calculation of reinforcement forbeams, columns and 2D (two dimensional) members is presented. Values of parameters do notdepend on UNIT command. In the file of input data only such parameters have to be taken,the values of which differ from determined in the program.



No. Parametername

DefaultValue

Description

1 NLT 1 Number of long-term loading case

2 RCL 3 Class of longitudinal reinforcement:

l RCL = 1, if class of reinforcement isA-I;

l RCL = 2, if class of reinforcement isA-II;

l RCL = 3, if class of reinforcement isA-III;

l RCL = 33, if class of reinforcement isA-IIIb;

l RCL = 4, if class of reinforcement isA-IV;

l RCL = 5, if class of reinforcement isA-V;

l RCL = 6, if class of reinforcement isA-VI;

l RCL = 7, if class of reinforcement isA-VII;

l RCL = 77, if class of reinforcement isK-7;

l RCL = 8, if class of reinforcement isB-II;

l RCL = 9, if class of reinforcement isBp-II;

l RCL = 10, if class of reinforcement isBp-I;

l RCL = 19, if class of reinforcement isK-19

Table 15A.1-Names of parameters for Concrete design according to RussianCode -СНиП 2.03.01-84* for beams.

701 — STAAD.Pro


No. Parametername

DefaultValue

Description

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;

l 13 = S500;

3 USM 1. Total product of service conditionscoefficients for longitudinal reinforcement(gs)

4 UB2 0.9 Specific service conditions coefficient forconcrete (gb2)

5 DD1 16. Diameter of longitudinal reinforcementbars in beam tension zone

6 DD2 16. Diameter of shear reinforcement bars forbeam;

7 BCL 15. Compression class of concrete


No. Parametername

DefaultValue

Description

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

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 conditions coefficientsfor concrete, except UB2 (gb)

703— STAAD.Pro


No. Parametername

DefaultValue

Description

9 TEM 0. Parameter of concrete hardeningconditions:

l TEM=0, for natural hardeningconditions;

l TEM=1, for steam hardeningconditions

10 CL1 0.05 Distance from top/bottom fiber of beamcross section to the center of longitudinalreinforcement bar;

11 CL2 0.05 Distance from left/right side of beam crosssection to the center of longitudinalreinforcement bar

12 WST 0.4 Ultimate width of short-term crack

13 WLT 0.3 Ultimate width of long-term crack

14 SSE 0 Limit state parameter for beam design

l SSE=0, if calculation ofreinforcement amount must becarried out according to therequirements of load carryingcapacity (the first limit state);

l SSE=1, if calculation ofreinforcement amount must becarried out according to thecracking requirements (the secondlimit state)


No. Parametername

DefaultValue

Description

15 RSH 1 Class of shear reinforcement:

l RSH = 1, if class of reinforcement isA-I;

l RSH = 2, if class of reinforcement isA-II;

l RSH = 3, if class of reinforcement isA-III;

l RSH = 33, if class of reinforcement isA-IIIb;

l RSH = 4, if class of reinforcement isA-IV;

l RSH = 5, if class of reinforcement isA-V;

l RSH = 6, if class of reinforcement isA-VI;

l RSH = 7, if class of reinforcement isA-VII;

l RSH = 77, if class of reinforcement isK-7;

l RSH = 8, if class of reinforcement isB-II;

l RSH = 9, if class of reinforcement isBp-II;

l RSH = 10, if class of reinforcement isBp-I;

l RSH = 19, if class of reinforcement isK-19

705— STAAD.Pro


No. Parametername

DefaultValue

Description

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 forbeam design only with default valueprovided as ZD in member properties.

17 FWB ZB Design width of beam bottom flange. Usefor beam design only with default valueprovided as ZB in member properties.

18 DEP YD Design depth of beam section. Use forbeam design only with default valueprovided as YD in member properties.

19 SFA 0. Face of support location at the start of thebeam. Use for beam design only.

20 EFA 0. Face of support location at the end of thebeam. Use for beam design only.

21 NSE 13 Number of equally-spaced sections forbeam design. Use for beam design only.Upper limit is equal to 20.

No. ParameterName

DefaultValue

Description


Table 15A.2-Names of parameters for Concrete design according to RussianCode СНиП 2.03.01-84* for columns


No. ParameterName

DefaultValue

Description


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;



5 DD1 16. Minimum diameter of longitudinalreinforcement bars for column

6 DD2 16. Maximum diameter of longitudinalreinforcement bars for column

707— STAAD.Pro


No. ParameterName

DefaultValue

Description

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

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



No. ParameterName

DefaultValue

Description




10 CL1 0.05 Distance from edge of column cross sectionto the center of longitudinal reinforcementbar

11 ELY 1. Column's length coefficient to evaluateslenderness effect in local Y axis

12 ELZ 1. Column's length coefficient to evaluateslenderness effect in local Z axis

13 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;

No. ParameterName

DefaultValue

Description


Table 15A.3-Names of parameters for Concrete design according to RussianCode (SNiP 2.03.01-84*) for slabs and/or walls

709— STAAD.Pro


No. ParameterName

DefaultValue

Description


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;



5 SDX 16. Diameter of reinforcing bars located in thefirst local (X) direction of slab/wall

6 SDY 16. Diameter of reinforcing bars located in thesecond local (Y) direction of slab/wall


No. ParameterName

DefaultValue

Description

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

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


711 — STAAD.Pro


No. ParameterName

DefaultValue

Description




10 CL 0.05 Distance from top/bottom face of slab/wallelement to the center of longitudinalreinforcing bars located in first local (X)direction. (Main thickness of top/bottomconcrete cover for slab/wall element)

11 CRA 0.05 Distance from top/bottom face of slab/wallelement to the center of transversereinforcing bars located in second local (Y)direction (Secondary thickness oftop/bottom concrete cover for slab/wall)

12 WST 0.4 Ultimate width of short-term crack

13 WLT 0.3 Ultimate width of long-term crack


No. ParameterName

DefaultValue

Description

14 STA 0 Parameter of limit state for slab/walldesign:

l STA=0, if calculation ofnonsymmetrical reinforcementmust be carried out according tothe requirements of load carryingcapacity (the first limit state);

l STA=1, if calculation of symmetricalreinforcement must be carried outaccording to the requirements ofload carrying capacity (the firstlimit state);

l STA=2, if calculation ofnonsymmetrical reinforcementmust be carried according to thecracking requirements (the secondlimit state);

l STA=3, if calculation of symmetricalreinforcement must be carriedaccording to the crackingrequirements (the second limitstate)

15 SELX 0. Design length of wall member to evaluateslenderness effect in local X axis

16 SELY 0. Design length of wall member to evaluateslenderness effect in local Y 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 reinforcement calculationmust be applied by principal stresses

713— STAAD.Pro


No. ParameterName

DefaultValue

Description

18 MMB 1 Design parameter of slab/wallreinforcement:

l MMB=0, if the effect of additionaleccentricity is not taken intoaccount;

l MMB=1, if the effect of additionaleccentricity is taken into 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;

l 12 = S400;

l 13 = S500;

15A.3 BeamsReinforcement for beams of rectangular and T cross-section can be calculated. In calculation of

longitudinal reinforcement bending moment about local axis and torsional moments areconsidered, but influence of longitudinal forces and bending moments in relation to local axis

is ignored. In calculation of transverse reinforcement shear forces parallel to local axisand torsional moments are taken into account.

Reinforcement for beams can be calculated either from conditions of strength or fromconditions of open crack width limitation (see parameter SSE).

Parameters SFA and ЕFA are considered only in calculation of transverse reinforcement.

In general case calculation of reinforcement for beams is carried out two times – according tostrength conditions and according to conditions of open crack width limitation. Inreinforcement calculations from conditions of strength design values of load have to be takenand in calculations from conditions of crack width limitation – characteristic (normative) load


values are used. Both calculations can be carried out in one session with the use multipleanalysis possibility of the program STAAD.Pro.

In most cases calculation of reinforcement is carried out with account only of a part ofloadings. In such cases command LOAD LIST is used, in which numbers of loads consideredin calculation are indicated. Number of permanent and long-term loads equal to parameterNLT must be included into the list of considered loads.

It has to be noted, that values of parameters DD1 and DD2 have influence not only on thewidth of opened crack but also in some cases, on design and normative reinforcementresistances.

Parameter BCL can be equal to any value of concrete compression strength class given inSNiP 2.03.01−84* and to any intermediate value as well.

It should be remembered, that accuracy of results of calculation of transverse reinforcementincreases with the value of parameter NSE.

Parameters SFA and ЕFA are considered only in calculations of transverse reinforcement.Beam 1 is shown in Figure 2 with rigid intervals the lengths of which are: at the start of thebeam 0.3m and at the end – 0.2m. In modeling of the beam the following command can beused.

MEMBER OFFSET

1 START 0.3 0 0

1 END -0.2 0 0

Figure 12A.2 - Diagram of a beam with rigid intervals

When command MEMBER OFFSET is used forces corresponding to the beam the length ofwhich is equal to the distance between points a and b are calculated and then used incalculation of reinforcement. In such case it is necessary to take into account default values ofparameters SFA and ЕFA equal to zero.

When command MEMBER OFFSET is not used forces corresponding to the beam the lengthof which is equal to the distance between points 10 and 11 are calculated and then used incalculation of reinforcement. In this case it is necessary to consider values of parametersSFA=0.3 and ЕFA=0,2 in reinforcement calculation.

715— STAAD.Pro


In both cases calculated quantity of transverse reinforcement will be the same. Calculatedquantity of longitudinal reinforcement in the second case will be greater.

For beam the following output is generated:

l beam number;

l method of calculation (according to conditions of strength or limitations of openedcrack width);

l length and cross-sectional dimensions;

l distance from resultant of forces acting in bottom/top reinforcement to bottom/topedge of the section;

l distance from the side edge of cross-section of the beam web to the centroid oflongitudinal bars located at this edge;

l concrete class;

l class of longitudinal and transverse reinforcement;

l assumed in calculations bar diameters of longitudinal and transverse reinforcement;

l calculation results of longitudinal and transverse reinforcement (in two tables).

In nine columns of the first table the following results are presented:

Result Description

Section distance of the section from the “start” ofthe beam, мм

As- cross-sectional area of longitudinalreinforcement in the bottom zone of cross-section of the beam, if angle BETA=0°, or inthe top zone, if BETA=180° , sq.cm

As+ cross-sectional area of longitudinalreinforcement in the top zone of cross-section of the beam , if angle BETA=0°, orin the top zone, if BETA=180° , sq.cm

Moments (-/+)

values of bending moments, determiningcross-sectional areas of longitudinalreinforcement As- and As+ , kNm

Load. N. (-/+)

numbers of loading versions, determiningcross-sectional areas of longitudinalreinforcement

Acrc1 short-term opened crack width*, mm

Acrc2 long-term opened crack width*, mm

Table 15A.4-Beam design output 1


* Opened crack width is presented only in the case when calculation is performed accordingto 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” ofthe 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 localaxis, kN

T value of torsional moment, kNm

Load N. number of loading version, determiningintensity of transverse reinforcement

Table 15A.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

Section As-As+ Moments(-/+) Load.N.(-/+) Acrc1 Acrc2

mm sq.cm kNm mm mm

717— STAAD.Pro


---------------------------------------------------------------------

0. 10.92 0.41 -152. / 2. 6 / 4 0.237 0.121

500. 4.74 0.41 -60. / 0. 5 / 0 0.294 0.157

1000. 1.13 1.13 -5. / 17. 4 / 6 0.000 0.000

1500. 1.13 6.41 -8. / 75. 4 / 6 0.295 0.147

2000. 1.13 9.24 -11. / 115. 4 / 6 0.298 0.149

2500. 1.13 11.53 -14. / 139. 4 / 6 0.271 0.134

3000. 1.19 12.16 -18. / 144. 4 / 6 0.263 0.127

3500. 1.41 10.86 -21. / 132. 4 / 6 0.277 0.130

4000. 1.63 8.28 -24. / 103. 4 / 6 0.296 0.129

4500. 1.95 4.54 -27. / 56. 4 / 6 0.299 0.093

5000. 3.23 0.58 -39. / 9. 5 / 3 0.293 0.157

5500. 0.74 0.41 -124. / 0. 5 / 0 0.271 0.142

6000. 16.89 0.41 -226. / 0. 5 / 0 0.155 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

2000. Minimum detailing requirements ! -63.9 0.0 6

2500. Minimum detailing requirements ! -28.9 0.0 6

3000. Minimum detailing requirements ! 12.7 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 required according tocalculation.

15A.4 ColumnsReinforcement for columns of rectangular or circular cross-section can be calculated. Flexibilityof columns can be evaluated in two ways. In the case of usual analysis (command PERFORM


ANALYSIS) flexibility is assessed by parameters ELY and ELZ, values of which shouldconform with recommendation of the Code SNiP 2.03.01-84*. If P-DELTA (analysis accordingto deformed diagram) or NONLINEAR (nonlinear geometry) analysis is performed, values ofparameters ELY and ELZ should be close to zero, for example ELY = ELZ=0.01.

Longitudinal reinforcement for columns is calculated only from condition of strength.

Longitudinal forces and bending moments in relation to local axes and are takeninto account in longitudinal reinforcement calculations.

For rectangular columns the following output is generated:

l column number;

l column length and cross-sectional dimensions;

l distance of centroid of each longitudinal bar from the nearest edge of the cross-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 REINFORCEMENT thefollowing output is presented:

Result

Section distance of the section from the “start” of thecolumn, mm

Astot total cross-sectional area of longitudinalreinforcement, sq.cm

Asy cross-sectional area of longitudinalreinforcement bars at each edge of section,

directed parallel to the local axis , sq.cm

Table 15A.6-Column design output 1

719— STAAD.Pro


Result

Asz cross-sectional area of longitudinalreinforcement bars at each edge of section,

directed parallel to the local axis ,sq.cm

Percent reinforcement percentage in the section

Nx, Mz,My

respective values of longitudinal force andbending moments in relation to the local

axes and , determining cross-sectional area of longitudinal reinforcement

Load.N. number of loading version, determiningcross-sectional area of longitudinalreinforcement

An example of output of calculation results is presented below.

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 T


Section

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 as well asquantity of longitudinal bars at each edge of the section obtained from calculation should beconsidered as recommendation. In this case arrangement of reinforcement in the sectiondepends on the orientation of the local axes and is as follows:

Calculated values of reinforcement cross-sectional areas are presented in the table and theymay 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 is derived.

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 reinforcement bars;

l diameter of longitudinal reinforcement bars obtained from calculation;

l quantity of longitudinal bars.

In seven columns of the table under the heading LONGITUDINAL REINFORCEMENT thefollowing results are presented:

Sec-tion

distance of the section from the “start” of the column, mm

Astot total cross-sectional area of longitudinal reinforcement, sq.cm

Percent

percentage of longitudinal reinforcement

721 — STAAD.Pro


Nx,Mz,My

respective values of longitudinal force and bending moments in relation to

local axis and , determining cross-sectional area of longitudinalreinforcement

Load.N.

number of loading version, determining cross-sectional area of longitudinalreinforcement

An example of output of calculation results for a column of circular section is presented 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 as well asquantity of longitudinal bars at each edge of the section should be considered asrecommendation.

Arrangement of reinforcement in section in this case is shown below:

Calculated cross-sectional areas of reinforcement presented in the table may differ fromrecommended on the lower side.


When according to detailing provisions it is not possible to arrange in the columnlongitudinal reinforcement obtained from calculation additional message is derived.

15A.5 Two DimensionalElement (slabs, walls, shells)In general case calculation of reinforcement for 2D members is carried out two times –according to conditions of strength and conditions of limiting opened width of cracks. Ifreinforcement is calculated according to conditions of strength, design values of loads have tobe used, and for conditions of limiting crack width – characteristic (normative) loads areemployed. Both calculations can be made in one session taking advantage of multiple analysispossibility of the program STAAD.Pro.

Symmetric or nonsymmetrical reinforcement of 2D members is calculated according toconditions of strength or according to conditions of limiting opened crack width (see forexample STA).

In reinforcement calculation for 2D members it is necessary to pay attention to arrangementof local axes of member and direction of reinforcement (see for example 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)Ele-ment

Asx

sq.cm/-m

Mx

kNm/-m

Nx

kN/-m

Load.-N.

(X)

Asy

sq.cm/-m

My

kNm/-m

Ny

kN/-m

Loa-dN.

(Y)60TOP

0.00 - 4.9 0.00 1 0.00 - 4.5 0.00 1

BOT 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:

723— STAAD.Pro


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 15A.7-Slab design output

Figure 2 - Local coordinate system of 2D member and notation of forces


725— STAAD.Pro

15B. Russian Codes - Steel Design Per SNiP 2.23-81*(Edition 1999)

STAAD.Pro is capable of performing steel design based on the Russian code СНиП II-23-81*Часть II Нормы проектирования Стальные конструкции (SNiP 2.23-81* Part II DesignStandards for Steel Construction).

Design of members per SNiP 2.23-81* requires the STAAD E. Eurozone Design CodesSELECT Code Pack.

15B.1 GeneralDesign Code SNiP Steel Structures as majority of modern codes is based on the method oflimit 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 residualdeformations, displacements, yielding of materials or opening of cracks.

l The second group is concerned with states of structures making worse normal theirservice 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) loadsand actions, which can cause failure of structures.

Analysis of structures for the second limit state is performed using service (normative) loadsand actions. Relation between design and normative loads is referred to as coefficient of loadreliability, 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.- 85 shall be takenin to account determining loads or their combinations.

In this version of the program only members from rolled, tube and roll-formed assortmentsections and also from compound such as double angles of T-type sections, double channelsare presented. Design of other members of compound section will be presented in otherversions of the program.

Economy of selected section is indicated by ratio (RATIO) σ/Ryyc presented in calculationresults. A section is economical when said ratio equals to 0,9 – 0,95.

15B.2 Built-in Russian Steel Section LibraryTypical sections of members being checked and selected according to SNiP 2.01.07.- 81* arepresented in the following tables.


Section Section Type Designation form

I-beam (GOST 8239-89) ST I12

Regular I-beam (GOST26020-83)

ST B1-10

Broad-flanged I-beam (GOST26020-83)

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

ST TUBE TH 0.003 WT0.12 DT 0.16

Table 15B.1-Typical Sections for Russian Steel Design

727— STAAD.Pro

15B. Russian Codes - Steel Design Per SNiP 2.23-81* (Edition 1999)

Section Section Type 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


Double unequal legs angles with shortlegs back to back

SDL125x80x10SP 0.01


Tee with flange at the top

Note: Flange of Tee beam is at thetop part of cross-section ifbeta angle = 0°, or at thebottom part if beta angle =180°.

T I12

T B1-10

T SH1-23

T K1-20

Table 15B.2-Compound Sections for Russian Steel Design

For entry of cross-sectional dimensions command MEMBER PROPERTIES RUSSIAN is used.


15B.2.1 Example

UNITS METER

MEMBER PROPERTY RUSSIAN

* I-BEAM

1 TO 6 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-SECTIONAL DIMENSIONS DEFINED BY CLIENT

47 TO 60 TABLE ST PIPE OD 0.102 ID 0.055

* SQUARE TUBE FROM ASSORTMENT

61 TO 68 TABLE ST TUB120X120X3

* RECTANGULAR TUBE OF CROSS-SECTIONAL DIMENSION DEFINED BY CLIENT

69 TO 95 TABLE ST TUBE TH 0.003 WT 0.12 DT 0.16

* DOUBLE CHANNEL (DISTANCE BETWEEN WALLS 10 ММ)

96 TO 103 TABLE D C14 SP 0.01

* DOUBLE UNEQUAL LEGS ANGLES WITH SHORT LEGS BACK-TO-BACK(DISTANCE BETWEEN WALLS 10 ММ)

104 TO 105 TABLE SD L125X80X10 SP 0.01

* MEMBER OF TEE SECTION

106 TO 126 TABLE T SH1-23

* FLANGE OF T-BEAMS AT THE BOTTOM OF CROSS-SECTION

BETA 180. MEMB 116 TO 126

* ORIENTATION OF THE LOCAL ANGLE AXES IN RELATION TO THE GLOBALAXES OF THE STRUCTURE

BETA RANGLE MEMB 12 TO 30

COMMANDS OF OUTPUT DATA FOR CHECK AND SELECTION OF SECTIONS ARELOCATED AFTER COMMANDS OF ANALYSIS AND, AS A RULE, AFTER OUTPUTCOMMAND TO PRINT RESULTS OF CALCULATION.

15B.3 Member CapacitiesAlgorithms for selection and review of sections for steel members according to assortmentsand databases of the main rolled steel producers from given countries and according tointernational standards as well are included in STAAD.Pro program. In this program versiononly assortment sections can be utilized.

729— STAAD.Pro


15B.3.1 Example

* COMMAND OF ANALYSIS

PERFORM ANALYSIS

* COMMAND OF LOADINGS AND THEIR COMBINATIONS CONSIDERED IN DESIGN

LOAD LIST 1 5 TO 9

* COMMAND TO START DESIGN ACCORDING TO RUSSIAN 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 TO 4

MAIN 1. ALL

SGR 3. ALL

SBLT 0 ALL

* PARAMETER OF OUTPUT AMOUNT OF INFORMATION ON CALCULATION RESULTS

TRACK 2. ALL

.

* COMMAND TO START SECTION CHECK PROCEDURE

CHECK CODE ALL

* COMMAND TO START SECTION SELECTION PROCEDURE

SELECT ALL

.

* COMMAND OF OUTPUT TO PRINT CONTENT OF ASSORTMENT TABLES

PRINT ENTIRE TABLE

* COMMAND OF OUTPUT TO PRINT SUMMARY OF STEEL ACCORDING TOSECTIONS

STEEL TAKE OFF

* COMMAND OF OUTPUT TO PRINT SUMMARY OF STEEL ACCORDING TO MEMBERSAND SECTIONS

STEEL MEMBER TAKE OFF

15B.3.2 Axial tension members

Stress in a section of axial tension member shall not exceed design strength Ry of selected steelmultiplied by coefficient of service conditions γc (KY and KZ), table 6 of SNiP 2.01.07.- 81*.Slenderness of tension member (CMM) shall not exceed slenderness limit indicated in table 20of SNiP 2.01.07.- 81* (default value λu = 200, but another value can be defined). Net section


factor (ratio Anet/Agross (NSF)) is used for tension member to allow for reduction of designcross-section area.

15B.3.3 Axial compression members

All axial compression members are calculated as long bars, i.e., with allowance for slenderness(λ = l0/imin). The calculation is performed in accordance with the clause 5.3 of SNiP 2.01.07.-81*, buckling coefficient φ is determined by formula 8-10. Effective bar lengths (within andout of plane) taking in to account role and location of the bar in the structure, as well asfixation of ends (l0 = μl), are determined according to requirements of chapter 6 or addition6 to SNiP 2.01.07.- 81* and are set by specification of members. Slenderness of compressionmembers (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. Limit slendernessvalue depends on stress acting in the member, section area, buckling coefficient and designresistance of steel.

Since slenderness can be different in various planes the greatest slenderness is assumed incalculations.

15B.3.4 Flexural members

Members subjected to the action of bending moments and shear forces are called flexuralmembers.

Calculation of flexural members consists of verification of strength, stability and deflection.

Normal and tangential stresses are verified by strength calculation of members. Normalstresses are calculated in the outermost section fibres. Tangential stresses are verified in theneutral axis zone of the same section. If normal stresses do not exceed design steel strengthand tangential stresses do not exceed design value of steel shear strength Rsγs then accordingto clause 5.14 of SNiP 2.01.07.- 81* principal stresses are checked.

General stability of member subjected to bending in one plane are calculated in accordancewith clause 5.15 of SNiP 2.01.07.- 81*, and subjected to bending in two planes – in accordancewith “Guide to design of steel structures” (to SNiP 2.01.07.- 81*). Coefficient φb value isdetermined 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 ofapplied load are required. For closed sections it is assumed that coefficient φb= 1.0.

Simply supported (non-continuous) beams can be calculated in elastic as well as in elastic-plastic state according to requirements of clause 5.18 of SNiP 2.01.07.- 81*. Calculation can beselected by specification of structure in input data.

Stiffness of flexural members is verified comparing input value of deflection limit (throughparameter DFF) with maximum displacement of a section of flexural member allowing forload reliability coefficient, which is specified, in input data. Limit values of deflection aredetermined 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 ofreview (CHECK) problem.

731 — STAAD.Pro


15B.3.5 Eccentric compression/tension members

Eccentric compression or tension members are subjected to simultaneous action of axial forceand bending moment. Bending moment appears due to eccentric application of longitudinalforce or due to transverse force.

Stress in eccentric compression/tension members is obtained as a sum of stresses due to axialforce and bending.

Following the requirements of clause 5.25 of SNiP 2.01.07.- 81* resistance of eccentriccompression/tension member taking into consideration condition Ry< 530 MPa, τ < 0.5Rs andN/(AnRy) > 0.1 is calculated by formula 49, and in other cases-by formula 50. Calculations ofstability verification are performed according to requirements of clauses 5.27, 5.30, 5.32 or 5.34.

Calculation for strength of eccentric tension members is made according to formula 50 ofSNiP 2.01.07.- 81*.

When reduced relative eccentricity mef> 20 eccentric compression members are calculated asflexural members (N = 0), when mef< 20 strength by formula 49 is not verified (clause 5.24).

15B.4 Design ParametersInformation on parameters, data used for check and selection of sections in design of steelstructures according to Russian Code is presented in the following table.

In this version of calculation according to requirements of SNiP 2.01.07.- 81* there is commondatabase of equal legs angles and unequal legs angles, therefore solution of section selectionproblem may give equal legs angle as well as unequal legs angle irrespective of set at thebeginning. The same is and with rectangular and square tubes.

Values of parameters do not depend on command UNIT. Only these values of parameters,which differ from, defined in the program need to be included in the input data file.

Review of sections (command CHECK) can be performed according to the first and the secondgroup of limit states. Selection of section (command SELECT) can be performed only accordingto the first group of limit states with subsequent recalculation and verification of selectedsection with allowance for deflection.

Calculation for the first group of limit states involves selection of members according tostrength and stability. Parameters CMN and CMM give opportunity to set slenderness limit forcompression and tension members respectively for their stability calculation, or refuseconsideration of slenderness by setting default parameters. In this case selection of sectionswill be performed with consideration only of strength check.

Check for deflection performed by setting parameter DFF (maximum allowable relativedeflection value) different from set in the program.

In the case of application of steel not defined by SNiP and/or GOST it is necessary to set theirdesign strength by parameters UNL and PY.

In determination of steel parameters SBLT and MAIN shall be approved (see Table 12B.4).



ParameterName

DefaultValue

Description

BEAM 1

Member design parameter:

l BEAM = 0, Design members for forces attheir ends or at the sections defined bySECTION command;

l BEAM = 1, Calculate the major axismoment Mz at 13 points along the beamand design beam at the location ofmaximum Mz;

l BEAM = 2, Same as BEAM=1, butadditional checks are carried out at beamends and at critical inter mediate section;

l BEAM = 3, Calculate forces at 13 pointsand perform design checks at all locationsincluding the ends

CB 1

Place of loading on beam:

l CB = 1, for loading on top flange;

l CB = 2, for loading on bottom flange

Table 15B.3-Parameters for Steel design according to Russian Code (SNiP II– 23 – 81*, edition 1990)

733— STAAD.Pro


ParameterName

DefaultValue

Description

СMM 0

Slenderness limit value for tension members:

l СMM = 0, if slenderness is suppressed;

l СMM = 2, if ultimate slenderness value is"150";





l СMM = 6, if ultimate slenderness value is"400

Set slenderness limit value not equal to "0" fordesign with evaluation of buckling effect


ParameterName

DefaultValue

Description

CMN 0

Slenderness limit value for compressionmembers:

l СMN = 0, if slenderness is suppressed;

l СMN = 1, if slenderness limit value is"120";

l СMN = 2, if slenderness limit value is"210-60a";








Set slenderness limit value not equal to "0" fordesign with evaluation of buckling effect

DFF 0.

Allowable limit of relative local deflection(Member length/Deflection Ratio):

Default value 0 is valid if design is appliedwithout deflection limitation.

Set for deflection check only

DMAX

[m]1. Maximum allowable section depth

DMIN

[m]0. Minimum allowable section depth

735— STAAD.Pro


ParameterName

DefaultValue

Description

GAMC1 1.0Specific service condition coefficient for bucklingdesign

GAMC2 1.0Specific service condition coefficient for strengthdesign

KY 1.0Coefficient of effective length in respect to localaxis Y (in plane XZ)

KZ 1.0Coefficient of effective length in respect to localaxis Z (in plane XY)

LEG 4

Type and position of loading on beam:

l LEG = 1, for loading concentrated in themiddle span;

l LEG = 2, for loading concentrated in thequarter of the span;

l LEG = 3, for loading concentrated at theend of bracket;

l LEG = 4, for loading uniformlydistributed on beam;

l LEG = 5, for loading uniformly distributedon bracket

LY

[m]

Memberlength

Effective length in respect to local axis Y (inplane XZ)

Default is selected member's length

LZ

[m]

Memberlength

Effective length in respect to local axis Z (inplane XY)

Default is selected member's length


ParameterName

DefaultValue

Description

MAIN 1

Standard of steel grade (GOST):

l MAIN = 1, if Standard of steel grade isGOST27772-88;




l MAIN = 5, if Standard of steel grade isTY14-3-567-76

NSF 1.0Net section factor for tension members or websection area weakening factor for bendingmembers

PY

[MPa]0

Design steel strength (yield strength):

If parameters MAIN according to Standard ofsteel grade (GOST) and by SGR according toSteel grade (STAL) are not defined

RATIO 1.0Ratio between design and characteristic loadsvalues

SBLT 0

Number of lateral bracing restraints along thespan:

l SBLT = 0, if beam not fixed;

l SBLT = 1, one restraint in the middle ofthe span;

l SBLT = 2, 3, etc. number of uniformlyspaced lateral supports along the span

737— STAAD.Pro


ParameterName

DefaultValue

Description

SGR 1 Steel grade (STAL). Refer to Table 12B.4 below.

TB 0

Indication of elastic or elastic-plastic calculation:

l TB = 0, for elastic calculation

l TB = 1, for elastic-plastic calculation

Set for members under bending or non-axialcompression/tension only.

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 (ultimate strength):

If parameters MAIN according to Standard ofsteel grade (GOST) and by SGR according toSteel grade (STAL) are not defined


SGRValue

SteelParameterMAIN

GOSTFor

members*

1 C235 1 GOST 27772-88 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

10 C390K 1 “ F

11 C440 1 “ F

12 C590 1 “ F

13 C590К 1 “ F

14 BSt3kp 2GOST 10705-80*

Tube

15 BSt3ps2

3

GOST 10705-80*

GOST 10706-76*

Tube

16 BSt3sp2

3

GOST 10705-80*

GOST 10706-76*

Tube

17 20 4 GOST 8731-87 Tube

18 16G2АF 5 TY 14-3-567-76 Tube

Table 15B.4-Steel types for design of steel structures according to SNiP2.01.07.-81* (table 51 and 51a)

*GT – members from sheet and roll-formed tubes

F – rolled section steel

739— STAAD.Pro


15B.5 Member Selection and Code CheckBoth code checking and member selection options are available in SNiP 2.23-81*.



Output of selection and check results are given in suppressed, extended and advanced 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 allcheck conditions (TRACK=1) and advanced – complete information on results of memberdesign (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 its direction (“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.

15B.5.1 Example of TRACK 0 output

In suppressed form (TRACK 0) results are presented according to the critical check for givenmember with indication of SNiP clause number, according to which strength safety of themember is minimum.

========================================================================MEMBER CROSS RESULT/ CRITICAL COND/ RATIO/ LOADING/

SECTION NO. FX MZ MY LOCATION


========================================================================1 I60 PASS SNiP- 5.18 0.68 1

0.000E+00 -4.650E+02 0.000E+00 3.000E+00

15B.5.2 Example of TRACK 1 output

In extended form (TRACK 1) results are presented on the basis of all required by SNiP checksfor given stress state.


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

15B.5.3 Example of a TRACK 2 output

In advanced form (TRACK=2) in addition to tabled results supplementary information ispresented.

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:

l Longitudinal force;

l Moments;

l Shear force.

741 — STAAD.Pro


Signs “+” and “-“ indicate direction of acting longitudinal force, bending moments and shearforces in accordance with sign rules assumed in program STAAD.

Check results in advanced form are presented with values of intermediate parameters byformulas in analytical and numerical expression with indication of SNiP clause.


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”, theirrespective meanings (i.e., addition, subtraction, division, multiplication, raising to the secondpower (squared), and square root). Conventional notations of stresses, coefficients andcharacteristics of steel resistance comply with accepted in the SNiP standard. Only Greekletters are changed by their names (e.g., , γc-GAMAC; α-ALPHA; β-BETA, η-ETA, φ-PHI, etc.).


743— STAAD.Pro

Section 16

Singaporian Codes


745— STAAD.Pro

16A. Singaporean Codes - Concrete Design per CP65STAAD.Pro is capable of performing concrete design based on the Singaporean code CP65Code of Practice for Structural Use of Concrete.

Design of members per CP65 requires the STAAD Asia Design Codes SELECT Code Pack.


747— STAAD.Pro

16A.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign per the CP65 code. These parameters not only act as a method to input required datafor code calculations but give the Engineer control over the actual design process. Defaultvalues of commonly used parameters for conventional design practice have been chosen as thebasis. Table 24.1 contains a complete list of available parameters with their default values.


ParameterName

DefaultValue

Description

CODE - Must be specified as CP65.


BRACE 0.0 Bracing parameter for column design:

0. Column braced in both directions


2. Column braced in only the local Zdirection.







Table 16A.1-Singaporean Concrete Design CP65 Parameters


ParameterName

DefaultValue

Description


FC 4.0 ksi Concrete Yield Stress / cube strength, incurrent units

FYMAIN 60 ksi Yield Stress for main reinforcement, in currentunits (For slabs, it is for reinforcement in bothdirections)

FYSEC 60 ksi Yield Stress for secondary reinforcement a, incurrent units. Applicable to shear bars inbeams.

MAXMAIN

50 mm Maximum required reinforcement bar sizeAcceptable bars are per MINMAIN above.


MINSEC 8 mm Minimum secondary bar size a. Applicable toshear reinforcement in beams


NSECTION



0. No serviceability check performed.

1. Perform serviceability check for beamsas if they were continuous.

2. Perform serviceability check for beamsas if they were simply supported.

3. Perform serviceability check for beamsas if they were cantilever beams.


749— STAAD.Pro

ParameterName

DefaultValue

Description

SRA 0.0 Skew angle considered in Wood & Armerequations where A is the angle in degrees.

Two special values are also considered:

0.0 = Orthogonal reinforcementlayout without consideringtorsional moment Mxy -slabsonly

-500 = Orthogonal reinforcementlayout with Mxy used tocalculate Wood & Armermoments for design.

TRACK 0.0 Controls level of detail in output:

0. Critical Moment will not be printedwith beam design report. Columndesign gives no detailed results.

1. For beam gives min/max steel % andspacing. For columns gives a detailedtable of output with additionalmoments calculated.

2. Beam design only. Details ofreinforcement at sections defined bythe NSECTION parameter.



751 — STAAD.Pro

Section 17

South African Codes


753— STAAD.Pro

17A. South African Codes - Concrete Design per SABS-0100-1

STAAD.Pro is capable of performing concrete design based on the South African code SABS-0100-1 2000 Code of Practice for Structural Use of Concrete Part1: Design. Design can beperformed for beams (flexure, shear, and torsion) and columns (axial load + biaxial bending).Given the width and depth (or diameter for circular columns) of a section, the programcalculates the required reinforcement.

Design of members per SABS-0100-1 requires the STAAD CAN/AUS/SA Design CodesSELECT Code Pack.

17A.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to SABS 0100-1. 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 valuesof commonly used parameters for conventional design practice have been chosen as the basis.Table 17A.1 contains a complete list of available parameters with their default values.


ParameterName


CODE - Must be specified as SABS0100.



BRACE 0.0 Column bracing:

0. Column braced in bothdirections.

1. Column braced about local Ydirection only

2. Column unbraced about local Zdirection only

3. Column unbraced in both Yand Z directions

CLB 20mm Clear Cover for outermost bottomreinforcement

Table 17A.1-South African Concrete Design SABS 0100-1 Parameters


ParameterName


CLS 20mm Clear Cover for outermost sidereinforcement

CLT 20mm Clear Cover for outermost topreinforcement

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

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 450 N/mm2 Yield Stress for main reinforcement, incurrent units.

FYSEC 450N/mm2 Yield Stress for secondaryreinforcement a, in current units.Applicable to shear bars in beams

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

MINMAIN 8mm Minimum main reinforcement bar sizeAcceptable bar sizes: 6 8 10 12 16 20 2528 32 36 40 50 60

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

755— STAAD.Pro


ParameterName


TRACK 0.0 Output detail

0. Critical Moment will not beprinted with beam designreport. Column design gives nodetailed results.

1. For beam gives min/max steel %and spacing. For columns givesa detailed table of output withadditional moments calculated.

2. Output of TRACK 1.0 List ofdesign sag/hog moments andcorresponding required steelarea at each section of member

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


UNIT MM

MEMBER PROPERTIES

*RECTANGULAR COLUMN 300MM WIDE X 450MM DEEP

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

*CIRCULAR COLUMN 300MM DIAMETER

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 x 300mm width)and the second set of members, with only depth and no width provided, will be assumed to becircular with 300mm diameter. Note that area (AX) is not provided for these members. If sheararea areas (AY & AZ ) are to be considered in analysis, the user may provide them along withYD and ZD. Also note that if moments of inertias are not provided, the program will calculatethem from YD and ZD. Finally a T section can be considered by using the third definitionabove.


17A.3 Beam DesignBeam design includes flexure, shear and torsion. For all types of beam action, all active beamloadings are scanned to create moment and shear envelopes and locate the critical sections.The total number of sections considered is thirteen. From the critical moment values, therequired positive and negative bar pattern is developed. Design for flexure is carried out as perclause no. 4.3.3.4.

Shear design as per SABS 0100 clause 4.3.4 has been followed and the procedure includescomputation of critical shear values. From these values, stirrup sizes are calculated withproper spacing. If torsion is present, the program will also consider the provisions of SABS0100 clause 4.3.5. Torsional reinforcement is separately 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

M30 Fe450 (Main) Fe450 (Sec.)

LENGTH: 6000.0 mm SIZE: 715.0 mm X 380.0 mm COVER: 40.0 mm

DESIGN LOAD SUMMARY (KN MET)---------------------------------------------------------------------------

-SECTION |FLEXURE (Maxm. Sagging/Hogging moments)| SHEAR(in mm) | MZ Load Case MX Load Case | VY P Load

Case---------------------------------------------------------------------------

-0.0 | 84.77 1 -9.89 1 | -28.13 4.39 1

| 0.00 0 |500.0 | 70.70 1 -9.89 1 | -28.13 4.39 1

| 0.00 0 |1000.0 | 56.64 1 -9.89 1 | -28.13 4.39 1

| 0.00 0 |1500.0 | 42.57 1 -9.89 1 | -28.13 4.39 1

| 0.00 0 |2000.0 | 28.50 1 -9.89 1 | -28.13 4.39 1

| 0.00 0 |2500.0 | 14.43 1 -9.89 1 | -28.13 4.39 1

| 0.00 0 |3000.0 | 0.37 1 -9.89 1 | -28.13 4.39 1

| 0.00 0 |3500.0 | 0.00 0 -9.89 1 | -28.13 4.39 1

| -13.70 1 |4000.0 | 0.00 0 -9.89 1 | -28.13 4.39 1

| -27.77 1 |4500.0 | 0.00 0 -9.89 1 | -28.13 4.39 1

| -41.84 1 |5000.0 | 0.00 0 -9.89 1 | -28.13 4.39 1

| -55.90 1 |5500.0 | 0.00 0 -9.89 1 | -28.13 4.39 1

| -69.97 1 |6000.0 | 0.00 0 -9.89 1 | -28.13 4.39 1

757— STAAD.Pro


| -84.04 1 |----------------------------------------------------------------------------

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 | 543.40/ 549.78( 7-10í )| 680.71/ 706.86( 9-10í )| 8í @ 115 mm500.0 | 543.40/ 549.78( 7-10í )| 567.75/ 603.18( 3-16í )| 8í @ 115 mm1000.0 | 543.40/ 549.78( 7-10í )| 454.79/ 471.24( 6-10í )| 8í @ 115 mm1500.0 | 543.40/ 549.78( 7-10í )| 353.21/ 392.70( 5-10í )| 8í @ 115 mm2000.0 | 543.40/ 549.78( 7-10í )| 353.21/ 392.70( 5-10í )| 8í @ 115 mm2500.0 | 543.40/ 549.78( 7-10í )| 353.21/ 392.70( 5-10í )| 8í @ 115 mm3000.0 | 543.40/ 549.78( 7-10í )| 353.21/ 392.70( 5-10í )| 8í @ 115 mm3500.0 | 353.21/ 392.70( 5-10í )| 543.40/ 549.78( 7-10í )| 8í @ 115 mm4000.0 | 353.21/ 392.70( 5-10í )| 543.40/ 549.78( 7-10í )| 8í @ 115 mm4500.0 | 353.21/ 392.70( 5-10í )| 543.40/ 549.78( 7-10í )| 8í @ 115 mm5000.0 | 448.91/ 452.40( 4-12í )| 543.40/ 549.78( 7-10í )| 8í @ 115 mm5500.0 | 561.87/ 565.50( 5-12í )| 543.40/ 549.78( 7-10í )| 8í @ 115 mm6000.0 | 674.83/ 678.60( 6-12í )| 543.40/ 549.78( 7-10í )| 8í @ 115 mm----------------------------------------------------------------------------

TORSION REINFORCEMENT : Not required

17A.4 Column DesignColumns are designed for axial force and biaxial bending at the ends. All active loadings aretested to calculate reinforcement. The loading which produces maximum reinforcement iscalled the critical load and is displayed. The requirements of SABS 0100-1 clause 4.7 arefollowed, with the user having control on the effective length in each direction by using theELZ and ELY parameters as described in table 12A.1. Bracing conditions are controlled by usingthe BRACE parameter. The program will then decide whether or not the column is short orslender and whether it requires additional moment calculations. For biaxial bending, therecommendations of 4.7.4.4 of the code are considered.

Column design is done for square, rectangular and circular sections. For rectangular andsquare sections, the reinforcement is always assumed to be arranged symmetrically. This causesslightly conservative results in certain cases.

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

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


M30 Fe450 (Main) Fe450 (Sec.)

LENGTH: 3000.0 mm CROSS SECTION: 715.0 mm X 380.0 mm COVER: 40.0 mm


DESIGN FORCES (KNS-MET)-----------------------DESIGN AXIAL FORCE (Pu) : -14.6

About Z About YINITIAL MOMENTS : 0.00 0.00


MOMENTS DUE TO MINIMUM ECC. : 0.28 0.29

SLENDERNESS RATIOS : 7.89 4.20ADDITION MOMENTS (Maddz and Maddy) : 0.00 0.00

TOTAL DESIGN MOMENTS : 45.17 9.41

REQD. STEEL AREA : 26.99 Sq.mm.REQD. CONCRETE AREA: 1213.61 Sq.mm.MAIN REINFORCEMENT : Provide 4 - 12 dia. (0.17%, 452.40 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 : 25.50 Muz1 : 45.22 Muy1 : 51.48

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

759— STAAD.Pro


17B. South African Codes - Steel Design Per SAB StandardSAB0162-1:1993

17B.1 GeneralThe design philosophy embodied in this specification is based on the concept of limit statedesign. Structures are designed and proportioned taking into consideration the limit states atwhich they would become unfit for their intended use. Two major categories of limit-state arerecognized - ultimate and serviceability. The primary considerations in ultimate limit statedesign are strength and stability, while that in serviceability is deflection. Appropriate load andresistance factors are used so that a uniform reliability is achieved for all steel structures undervarious loading conditions and at the same time the chances of limits being surpassed areacceptably remote.

In the STAAD implementation, members are proportioned to resist the design loads withoutexceeding the limit states of strength, stability and serviceability. Accordingly, the mosteconomic section is selected on the basis of the least weight criteria as augmented by thedesigner in specification of allowable member depths, desired section type, or other suchparameters. The code checking portion of the program checks whether code requirements foreach selected section are met and identifies the governing criteria.

The next few sections describe the salient features of the STAAD implementation of SAB0162-1:1993. A detailed description of the design process along with its underlying concepts andassumptions is available in the specification document.

17B.2 Analysis MethodologyElastic analysis method is used to obtain the forces and moments for design. Analysis is donefor the primary and combination loading conditions provided by the user. The user is allowedcomplete flexibility in providing loading specifications and using appropriate load factors tocreate necessary loading situations. Depending upon the analysis requirements, regularstiffness analysis or P-Delta analysis may be specified. Dynamic analysis may also be performedand the results combined with static analysis results.

Refer to Section 5.37 of the Technical Reference Manual for additional information.

17B.3 Member Property SpecificationsFor specification of member properties, the steel section library available in STAAD may beused. The next section describes the syntax of commands used to assign properties from thebuilt-in steel table. Member properties may also be specified using the User Table facility. Formore information on these facilities, refer to Section 1.7 the STAAD Technical ReferenceManual.

17B.4 Built-in Steel Section LibraryA steel section library consisting of South African Standards shapes is available for memberproperty specification.

The following information is provided for use when the built-in steel tables are to bereferenced for member property specification. These properties are stored in a database file. If


called for, the properties are also used for member design. Since the shear areas are built intothese tables, shear deformation is always considered during the analysis of these members.


17B.4.1 I Shapes

The following example illustrates the specification of I- shapes.

1 TO 15 TABLE ST IPE-AA100

17B.4.2 H shapes

Designation of H shapes in STAAD is as follows.

For example,

18 TO 20 TABLE ST 152X37UC

17B.4.3 PG shapes

Designation of PG shapes in STAAD is as follows.

100 TO 150 TABLE ST 720X200PG

17B.4.4 Channel Sections (C & MC shapes)

C and MC shapes are designated as shown in the following example.

3 TABLE ST 127X64X15C


Back to back double channels, with or without spacing between them, are specified bypreceding the section designation by the letter D. For example, a back to back double channelsection PFC140X60 without spacing in between should be specified as:

100 TO 150 TABLE D PFC140X60

A back-to-back double channel section 140X60X16C with spacing 0.01 unit length in betweenshould be specified as:

100 TO 150 TABLE D 140X60X16C SP 0.01

Note: The specification SP after the section designation is used for providing the spacing.The spacing should always be provided in the current length unit.

761 — STAAD.Pro

17B. South African Codes - Steel Design Per SAB Standard SAB0162-1:1993

17B.4.6 Angles

To specify angles, the letter L succeeds the angle name. Thus, a 70X70 angle with a 25mmthickness is designated as 70X70X8L. The following examples illustrate angle specifications.

100 TO 150 TABLE ST 70X70X8L

Note that the above specification is for “standard” angles. In this specification, the local z-axis(see Fig. 2.6 in the Technical Reference Manual) corresponds to the Y’-Y’ axis shown in theCSA table. Another common practice of specifying angles assumes the local y-axis tocorrespond to the Y’-Y’ axis. To specify angles in accordance with this convention, the reverseangle designation facility has been provided. A reverse angle may be specified by substitutingthe word ST with the word 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. 2.6 of theSTAAD Technical Reference manual.


To specify double angles, the specification ST should be substituted with LD (for long legback-to-back) or SD (short leg back-to-back). For equal angles, either SD or LD will serve thepurpose. Spacing between angles may be provided by using the word SP followed by the valueof spacing (in current length unit) after section designation.

100 TO 150 TABLE LD 50X50X3L

3 TABLE LD 40X40X5L SP 0.01

The second example above describes a double angle section consisting of 40X40X5 angles witha spacing of 0.01 length units.

17B.4.8 Tees

Tee sections obtained by cutting W sections may be specified by using the T specificationinstead 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.

17B.4.9 Rectangular Hollow Sections

These sections may be specified in two possible ways. Those sections listed in the SAB tablesmay 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(for width),and TH(for thickness) specifications. For example:

100 TO 150 TABLE ST TUBE TH 3 WT 100 DT 50

will describe a tube with a depth of 50mm, width of 100mm. and a wall thickness of 3mm.Note that the values of depth, width and thickness must be provided in current length unit.

17B.4.10 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 be specified byusing the OD (outside diameter) and ID (inside diameter) specifications.

For example:

100 TO 150 TABLE ST PIPE OD 50 ID 48

will describe a pipe with an outside diameter of 50 length units and inside diameter of 48length units. Note that the values of outside and inside diameters must be provided in termsof current length unit.

A sample input file to demonstrate usage of South African shapes:

STAAD PLANE


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 1.511.4 0;

13 7.5 11.4 0; 14 3 12.3 0; 15 6 12.3 0; 16 4.5 13.2 0;

763— STAAD.Pro


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

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 0 WT 0 DT 50

18 TABLE ST TUBE TH 0.02 WT 100 DT 50

20 TABLE ST PIP48X2.0CHS

21 TABLE ST PIPE OD 0.5 ID 0.48


FINISH

17B.5 Section ClassificationThe SAB specification allows inelastic deformation of section elements. Thus, local bucklingbecomes an important criterion. Steel sections are classified as plastic (Class 1), compact (Class2), noncompact (Class 3), or slender element (Class 4) sections depending upon their localbuckling characteristics (See Clause 11.2 and Table 1 of SAB0162-1:1993). This classification is afunction of the geometric properties of the section. The design procedures are differentdepending on the section class. STAAD determines the section classification for the standardshapes and user specified shapes. Design is performed for sections that fall into the category ofClass 1,2, or 3 sections only. Class 4 sections are not designed by STAAD.

17B.6 Member ResistancesThe member resistances are calculated in STAAD according to the procedures outlined insection 13 of the specification. These depend on several factors such as members’ unsupported


lengths, cross-sectional properties, slenderness factors, unsupported width to thickness ratiosand so on. Note that the program automatically takes into consideration appropriateresistance factors to calculate member resistances. Explained here is the procedure adopted inSTAAD for calculating the member resistances.

All the members are checked against allowable slenderness ratio as per Cl.10.2 of SAB0162-1:1993.

17B.6.1 Axial

Parameters FYLD, FU, and NSF are applicable for these calculations.

17B.6.2 Axial Compression

The compressive resistance of columns is determined based on Clause 13.3 of the code. Theequations presented in this section of the code assume that the compressive resistance is afunction of the compressive strength of the gross section (Gross section Area times the YieldStrength) as well as the slenderness factor (KL/r ratios). The effective length for thecalculation of compression resistance 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 axialcompression capacity in general column flexural buckling is calculated from Cl.13.3.1using the slenderness ratios for the local Y-Y and Z-Z axis. The parameters KY, LY, KZ,and LZ are applicable for this.

2. For single angles, asymmetric or cruciform sections are checked as to whethertorsional-flexural buckling is critical. But for KL/r ratio exceeding 50,as torsionalflexural buckling is not critical, the axial compression capacities are calculated by usingCl.13.3. The reason for this is that the South African code doesn’t provide any clearguidelines for calculating this value. The parameters KY, LY, KZ, and LZ are applicablefor this.

3. The axial compression capacity is also calculated by taking flexural-torsional bucklinginto account. Parameters KX and LX may be used to provide the effective length factorand effective length value for flexural-torsional buckling. Flexural-torsional bucklingcapacity is computed for single channels, single angles, Tees and Double angles.

4. While computing the general column flexural buckling capacity of sections with axialcompression + bending, the special provisions of 13.8.1(a), 13.8.1(b) and 13.8.1(c) areapplied. For example, Lambda = 0 for 13.8.1(a), K=1 for 13.8.1(b), etc.)

17B.6.3 Bending

The laterally unsupported length of the compression flange for the purpose of computing thefactored moment resistance is specified in STAAD with the help of the parameter UNL. IfUNL is less than one tenth the member length (member length is the distance between thejoints of the member), the member is treated as being continuously laterally supported. Inthis case, the moment resistance is computed from Clause 13.5 of the code. If UNL is greater

765— STAAD.Pro


than or equal to one-tenth the member length, its value is used as the laterally unsupportedlength. The equations 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 capacity calculations are:

1. The weak axis bending capacity of all sections except single angles is calculated 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 code doesn’tprovide any clear guidelines for calculating this value.

3. For calculating the bending capacity about the Z-Z axis of singly symmetric shapes suchas Tees and Double angles, SAB0162-1: 1993 stipulates in Clause 13.6(b), page 31, that arational method.

17B.6.4 Axial compression and bending

The member strength for sections subjected to axial compression and uniaxial or biaxialbending is obtained through the use of interaction equations. In these equations, theadditional bending caused by the action of the axial load is accounted for by usingamplification factors. Clause 13.8 of the code provides the equations for this purpose. If thesummation of the left hand side of these equations exceeds 1.0 or the allowable value providedusing the RATIO parameter (see Table 17B.1), the member is considered to have FAILed underthe loading condition.

17B.6.5 Axial tension and bending

Members subjected to axial tension and bending are also designed using interaction equations.Clause 13.9 of the code is used to perform these checks. The actual RATIO is determined as thevalue of the left hand side of the critical equation.

17B.6.6 Shear

The shear resistance of the cross section is determined using the equations of Clause 13.4 of thecode. Once this is obtained, the ratio of the shear force acting on the cross section to the shearresistance of the section is calculated. If any of the ratios (for both local Y & Z axes) exceed 1.0or the allowable value provided using the RATIO parameter (see Table 17B.1), the section is


considered to have failed under shear. The code also requires that the slenderness ratio of theweb be within a certain limit (See Cl.13.4.1.3, page 29 of SABS 0162-1:1993). Checks for safety inshear are performed only if this value is within the allowable limit. Users may by-pass thislimitation by specifying a value of 2.0 for the MAIN parameter.

17B.7 Design ParametersThe design parameters outlined in table below may be used to control the design procedure.These parameters communicate design decisions from the engineer to the program and thusallow the engineer to control the design process to suit an application's specific needs.



Param-eterName

DefaultValue

Description

CODE - Must be specified SAB0162.



BEAM 0 0 - Perform design at ends and those locationsspecified in the section command.

1 - Perform design at ends and 1/12th sectionlocations along member length.

CB 1.0 Greater than 0.0 and less than 2.5,Value ofOmega_2 (C1.13.6) to be used for calculation

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 isnot performed

Table 17B.1-South African Steel Design Parameters

767— STAAD.Pro


Param-eterName

DefaultValue

Description

DJ1 0 Start node of physical member for determiningdeflected pattern for deflection check andshould be set along with DFF parameter

DJ2 0 End node of physical member for determiningdeflected pattern for deflection check andshould be set along with DFF parameter

DMAX 1000 Maximum allowable depth

DMIN 0 Minimum required depth

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 Memberlength

Length for flexural torsional buckling

LY Memberlength

Length in local Y axis for slenderness valueKL/r

LZ Memberlength

Length in local Z axis for slenderness valueKL/r

MAIN 0 Flag for controlling slenderness check

0 - For Check for slenderness.

1 - For Do not check forslenderness


RATIO 1.0 Permissible ratio of applied load to sectioncapacity

Used in altering the RHS of critical interactionequations


Param-eterName

DefaultValue

Description

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 theminimum detail level.

1. Print the design output at theintermediate detail level.

2. Print the design output at maximumdetail level

UNB MemberLength

Unsupported length in bending compressionof bottom flange for calculating momentresistance

UNT MemberLength

Unsupported length in bending compressionof top flange for calculating moment resistance

17B.8 Code CheckingThe purpose of code checking is to determine whether the current section properties of themembers are adequate to carry the forces obtained from the most recent analysis. Theadequacy is checked as per the SAB0162-1: 1993 requirements.

Code checking is done using forces and moments at specified sections of the members. If theBEAM parameter for a member is set to 1 (which is also its default value), moments arecalculated at every twelfth point along the beam. When no section locations are specified andthe BEAM parameter is set to zero, design will be based on member start and end forces only.The code checking output labels the members as PASSed or FAILed. In addition, the criticalcondition, governing load case, location (distance from the start joint) and magnitudes of thegoverning forces and moments are also printed. Using the TRACK parameter can control theextent of detail of the output.


769— STAAD.Pro


17B.8.1 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

CB 0 MEMB 1 TO 23

CMZ MEMB 2 1 TO 23

CMY MEMB 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

17B.9 Member SelectionThe member selection process involves determination of the least weight member that PASSesthe code checking procedure based on the forces and moments of the most recent analysis.The section selected will be of the same type as that specified initially.

For example, a member specified initially as a channel will have a channel selected for it.Selection of members whose properties are originally provided from a user table will be limitedto sections in the user table. Member selection cannot be performed on members listed asPRISMATIC.


17B.10 Tabulated Results of Steel DesignResults of code checking and member selection are presented in a tabular format. The termCRITICAL COND refers to the section of the SAB0162-1: 1993 specification, which governed thedesign.

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))**************************************



FX MY MZLOCATION

==================================================================-=====

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 some of theitems 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 track 2.0parameter is as follows.

**************************************STAAD.PRO CODE CHECKING




FX MY MZLOCATION

771 — STAAD.Pro


===================================================================-====

1 ST 406X67UB (SOUTHAFRICAN SECTIONS)PASS SAB-13.8 0.543

10.00 0.00 -191.90

4.08


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


FYLD = 300.0 FU = 345.0


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


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.


CRY Factored compressive resistance for column bucklingabout the local y axis

CRZ Factored compressive resistance for column bucklingabout the local z axis

CTORFLX Factored compressive resistance against torsionalflexural buckling

TENSILECAPACITY

Factored tensile capacity

COMPRESSIVECAPACITY

Factored compressive capacity



FACTOREDMOMENTRESISTANCE

MRY = Factored moment of resistance in y direction

MRZ = Factored moment of resistance in z direction

FACTOREDSHEARRESISTANCE

VRY = Factored shear resistance in y direction

VRZ = Factored shear resistance in z direction

17B.11 Verification ProblemsIn the next few pages are included three verification examples for reference purposes.


Determine the capacity of a South African I-section column in axial compression per SouthAfrican steel design code (SAB:0162-1(1993)) . Column is braced at its ends for both axes.

Reference

Example 4.3.4.1, page 4.18, Structural Steel Design to SAB:0162-1(1993)(Limit state Design) byGreg Parrott, 1st edition, Shades Technical publication

Given

FYLD = 300 Mpa

Length = 6000 mm

Comparison


Axial Compressive Strength (kN) 1,516 1,516 none

Table 17B.2-SABS 0162-1:1993 Verification problem no.1 comparison

Input File

STAAD PLANE


ENGINEER DATE

END JOB INFORMATION

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 6 0;

MEMBER INCIDENCES

773— STAAD.Pro


1 1 2;


1 TABLE ST 356X67UB


ISOTROPIC STEEL

E 1.99947E+008

POISSON 0.3

DENSITY 76.8191

ALPHA 6E-006

DAMP 0.03

TYPE STEEL

STRENGTH FY 248210 FU 399894 RY 1.5 RT 1.2

END DEFINE MATERIAL

UNIT MMS KN

CONSTANTS

MATERIAL STEEL ALL

UNIT METER KN

SUPPORTS

1 FIXED


JOINT LOAD

2 FY -1500

PERFORM ANALYSIS

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



MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/


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

1 ST 356X67UB (SOUTHAFRICAN SECTIONS)PASS COMPRESSION 0.989 1

1500.00 0.00 0.00 0.00




FYLD = 300.0 FU = 345.0


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



17B.12 Verification Problem No. 2Determine the capacity of a South African I-section beam in bending per South African steeldesign code (SAB:0162-1(1993)). The beam has torsional and simple lateral rotational restraintat the supports, and the applied point load provides effective lateral restraint at the point ofapplication is braced at its ends for both axes.

17B.12.1 Reference

Example 4.5, page 4.37, Structural Steel Design to SAB:0162-1(1993)(Limit state Design) byGreg Parrott, 1st edition, Shades Technical publication

17B.12.2 Given

FYLD = 300 Mpa

775— STAAD.Pro


17B.12.3 Comparison


Major Axis Bending Resistance(kN)

353.4 353.3 none

Table 17B.3-SAB 0162 -1:1993 Verification Problem 2 comparison

17B.12.4 Input File

STAAD PLANE


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


1 2 TABLE ST 406X67UB


ISOTROPIC MATERIAL1

E 2.00E+008

POISSON 3

DENSITY 977

ISOTROPIC STEEL

E 2.00E+008

POISSON 3

DENSITY 8195

ALPHA 2E-005

DAMP 03

END DEFINE MATERIAL

UNIT MMS KN

CONSTANTS

MATERIAL STEEL MEMB 1 2

UNIT METER KN

SUPPORTS

1 3 PINNED


MEMBER LOAD


1 CON GY -104 4

1 UNI GY -4

2 UNI GY -2

PERFORM ANALYSIS

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 CODE MEMB 1

FINISH

17B.12.5 Output**************************************

STAAD.PRO CODE CHECKING(SOUTHAFRICAN STEEL/SAB-0162-01(1993))**************************************



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

1 ST 406X67UB (SOUTHAFRICAN SECTIONS)PASS SAB-13.8 0.543 10.00 0.00 -191.90 4.08




FYLD = 300.0 FU = 345.0




777— STAAD.Pro


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

17B.13 Verification Problem No. 3Determine the elastic shear capacity per South African steel design code (SAB:0162-1(1993)) of aSouth African I-section which is simply supported over the span of 8 m.

17B.13.1 Reference

Example 4.6.5, page 4.54, Structural Steel Design to SAB:0162-1(1993)(Limit state Design) byGreg Parrott, 1st edition, Shades Technical publication

17B.13.2 Given

FYLD = 300 Mpa

17B.13.3 Comparison


Shear Capacity (kN) 687.1 687.1 none

Table 17B.4-SAB 0162-1:1993 Verification Problem 3 comparison

17B.13.4 Input File

STAAD PLANE


ENGINEER DATE

END JOB INFORMATION

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 8 0 0

MEMBER INCIDENCES

1 1 2


1 TABLE ST 457X67UB


ISOTROPIC MATERIAL1

E 2E+008

POISSON 3

DENSITY 977

ISOTROPIC STEEL


E 2E+008

POISSON 3

DENSITY 8195

ALPHA 2E-005

DAMP 03

END DEFINE MATERIAL

UNIT MMS KN

CONSTANTS

MATERIAL STEEL MEMB 1

UNIT METER KN

SUPPORTS

1 2 PINNED


MEMBER LOAD

1 UNI GY -70

PERFORM ANALYSIS

PARAMETER

CODE SABS0162

FU 450000 ALL

BEAM 1 ALL

FYLD 300000 ALL

TRACK 2 ALL

CHECK CODE ALL

FINISH

17B.13.5 Output**************************************

STAAD.PRO CODE CHECKING(SOUTHAFRICAN STEEL/SAB-0162-01(1993))**************************************



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

* 1 ST 457X67UB (SOUTHAFRICAN SECTIONS)FAIL SAB-13.8 4.134 10.00 0.00 -560.00 4.00



MATERIAL PROPERTIES (UNIT = MPA)

779— STAAD.Pro


--------------------------------

FYLD = 300.0 FU = 345.0






781 — STAAD.Pro

Section 18

Spanish Codes


783— STAAD.Pro

18A. Spanish Codes - Steel Design per NBE-MV103-1972STAAD.Pro is capable of performing steel design based on the Spanish code NBE-MV103-1972Cálculo de estructuras de acero laminado en edificación (Calculation of rolled steel structuresconstruction).

Design of members per NBE-MV103-1972 requires the STAAD Eurozone Design CodesSELECT Code Pack.

18A.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to the BSK 99 code. These parameters not only act as a method to input required datafor code calculations but give the Engineer control over the actual design process. Defaultvalues of commonly used parameters for conventional design practice have been chosen as thebasis. Table 26A.1 contains a complete list of available parameters with their default values.


ParameterName


CODE - Must be specified as SPANISH.



0. Check sections with endforces only or at locationsspecified by a SECTIONcommand.

1. Calculate moment at 1/10thpoints along the beam andmaximum Mz for design

2. Check sections with endforces and forces at locationof BEAM 1.0 check.

C1 0 β value as specified in Sections 3.5.5.1and 3.9.4.1.

Table 18A.1-Spanish Steel Design per NBE-MV103-1972 Parameters


ParameterName


C2 0 β0 value as specified in Sections3.5.5.1 and 3.9.4.1.

CB 1 Controls the check Mcrrs as perSection 5.5.3.

0. Perform this check

1. Do not perform this check.

DFF None "Deflection Length" / Maximumallowable local deflection

DJ1 Start nodeof member

Node no. denoting starting point forcalculation of "Deflection Length" .

DJ2 End node of member Node no. denoting end point forcalculation of "Deflection Length".

DMAX 25.4 meter Maximum allowable depth of steelsection.

DMIN 0 Minimum allowable depth of steelsection.

ETA 1 Critical Cl. 5.1.3

1. Continue with other codechecks, even if the sectionfails the check per this clause

2. Consider the section failedand cease code checks if thesection fails the check perthis clause

FYLD 255 MPa Yield strength of steel.

KY 1.0 K factor in local y axis.

KZ 1.0 K factor in local z axis.

LVV Member Length Member length to be used in Cl.3.5.5.1.

LY Member Length Compression length in local y axis,Slenderness ratio = (KY)·(LY)/(ry)

LZ Member Length Compression length in local z axis,Slenderness ratio = (KZ)·(LZ)/(rz)

785— STAAD.Pro

18A. Spanish Codes - Steel Design per NBE-MV103-1972

ParameterName


MAIN 1 Sets the slenderness limit for checksper Section 3.5.6.

1. Main steel (200)

2. Secondary steel (250)

NSF 1.0 Net tension factor for tensioncapacity calculation.


TB 1 Net section factor for tensionmembers, as applied to Wn per Cl.4.5.

TRACK 0 Used to control the level of detail inthe output.

0. = Minimum level of detail

1. = Intermediate level of detail

2. = Maximum level of detail

UNF 1 Unsupported length as a fraction ofthe actual member length.

UNL Member Length Unsupported length for allowablebending stress.

18A. Spanish Codes - Concrete Design per EHESTAAD.Pro is capable of performing concrete design based on the Spanish code EHE Españoladel Hormigón Estructural (Spanish Structural Concrete).

Design of members per EHE requires the STAAD Eurozone Design Codes SELECT Code Pack.

18A.2 Design ParametersThese parameters not only act as a method to input required data for code calculations butgive the engineer control over the actual design process. Default values, which are commonlyused numbers in conventional design practice, have been used for simplicity. Table 25A.1contains a list of available parameters and their default values.



ParameterName

DefaultValue

Description

CLB 1.5 in Clear cover to reinforcing bar at bottom of crosssection.

CLS 1.5 in Clear cover to reinforcing bar along the side ofthe cross section.

CLT 1.5 in Clear cover to reinforcing bar at top of crosssection.

DEPTH YD Depth of the concrete member. This valuedefaults to YD as provided under MEMBERPROPERTIES.

EFACE 0.0 Faceof

Support

Distance of face of support from end node ofbeam. Used for shear and torsion calculation.

Note: Both SFACE & EFACE must be positivenumbers.

FC 4.0 ksi Specified compressive strength of concrete.

FYMAIN 60 ksi Yield Stress for main reinforcing steel.

FYSEC 60 ksi Yield Stress for secondary reinforcing steel.

MAXMAIN

Number55 bar

Maximum main reinforcement bar size.

MINMAIN Number10 bar

Minimum main reinforcement bar size

MINSEC Number10 bar

Minimum secondary (stirrup) reinforcement barsize.

MMAG 1.0 A factor by which the column design momentswill be magnified.

NSECTION

12 Number of equally-spaced sections to beconsidered in finding critical moments for beamdesign.

REINF 0.0 Used to specify type of column shearreinforcement:

0. Tied Column.

1. Spiral Column.

Table 18A.2-Spanish Concrete Design per EHE Parameters

787— STAAD.Pro

18A. Spanish Codes - Concrete Design per EHE

ParameterName

DefaultValue

Description

SFACE 0.0 Distance of face of support from start node ofbeam. Used for shear and torsion calculation.

Note: Both SFACE & EFACE must be positivenumbers.

TRACK 0.0 Used to specify detail of output:

0. Only minimum details are printed forbeam or column designs.

1. Beam Design: Intermediate level of detail.

Column Design: TRACK 0 output plusintermediate level of detail.

2. Beam Design: TRACK 1 detail plus steelrequired at 1/12th secitons.

Column Design: detailed output.



789— STAAD.Pro

Section 19

Swedish Codes


791 — STAAD.Pro

19A. Swedish Codes - Steel Design per BSK 99STAAD.Pro is capable of performing steel design based on the Swedish code BSK 99 SwedishRegulations for Steel Structures.

Design of members per BSK 99 requires the STAAD N. Eurozone Design Codes SELECT CodePack.

19A.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to the BSK 99 code. These parameters not only act as a method to input required datafor code calculations but give the Engineer control over the actual design process. Defaultvalues of commonly used parameters for conventional design practice have been chosen as thebasis. Table 19A.1 contains a complete list of available parameters with their default values.


ParameterName

DefaultValue

Description

CODE - Must be specified as BSK99.


BEAM 1 (Required) Directs the program to divide thebeam element into 13 equal length sections forsection checks.

BY 1 Buckling length coefficient, βcd, for bucklingabout the weak axis (typically y-y axis).

BZ 1 Buckling length coefficient, βcd for bucklingabout the strong axis (typically z-z axis).

CB 1 The reduction factor, CB, for the criticallateral buckling moment according to thetheory of elasticity.

CMY 1 Describes the boundary conditions for lateralbuckling.

CMZ 1 Depends on loading and boundary conditionsfor bending and controls Mlcr andcorresponding moments.

Table 19A.1-Swedish Steel Design per BSK 99 Parameters


ParameterName

DefaultValue

Description

CY 0 Buckling curve coefficient, β1, about local y-axis.

CZ 0 Buckling curve coefficient, β1, about local z-axis.

DMAX 1 meter Maximum allowable depth of steel section.

DMIN 0 Minimum allowable depth of steel section.

FYLD 235 MPa Yield strength of steel.

MF 1.15 Material factor and security class factor, γm·γn.

RATIO 1 Permissible ratio of loading to capacity.

SSY 0 Calculates the design moment about the y-axis.

SSZ 0 Calculates the design moment about the z-axis.

793— STAAD.Pro

19A. Swedish Codes - Steel Design per BSK 99

ParameterName

DefaultValue

Description

TRACK 0 Used to control the level of detail in theoutput.

0. = Suppress critical memberstresses (2 lines/member)

1. = Print all critical memberstress (i.e., design values) (6lines/beam)

2. = Print von Mises stresses

3. = Member results, sorted bymember number (2lines/member)

9. = Print detailed report foreach member

31. = Max./min. output for endno. 1

32. = Max./min. output for endno. 2

49. = Joint force output.

98. = Joint capacity.

99. = Joint capacity.

UNL MemberLength

Unrestraint length of member used incalculating the lateral-torsional resistancemoment of the member.


795— STAAD.Pro

19B. Swedish Codes - Concrete Design per BBK 94STAAD.Pro is capable of performing concrete design based on the Swedish code BBK 94Swedish Handbook for Concrete Structures.

Design of members per BBK 94 requires the STAAD N. Eurozone Design Codes SELECT CodePack.


797— STAAD.Pro

19C.1 Design ParametersThe program contains a number of parameters which are needed to perform and control thedesign to the BBK 94 code. These parameters not only act as a method to input required datafor code calculations but give the Engineer control over the actual design process. Defaultvalues of commonly used parameters for conventional design practice have been chosen as thebasis. Table 19B.1 contains a complete list of available parameters with their default values.


ParameterName

DefaultValue

Description

CODE - Must be specified as SWEDISH.


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 braced inonly the local Z direction.




DRYCIR 100 Drying exposure, in percent.



Table 19C.1-Swedish Concrete Design per BBK 94 Parameters


ParameterName

DefaultValue

Description







FC 35 N/mm2 Compressive strength of concrete.

FYMAIN 500 N/mm2 Yield strength of main reinforcing steel.


MAXMAIN

32 Maximum size permitted for mainreinforcement bar.

MINMAIN 10 Minimum size permitted for mainreinforcement bar.

MOY moy factor

MOZ moz factor

NMAG nmag factor


RELHUM 40 Relative humidity, in percent.



2. Two faced distribution about minoraxis.

3. Two faced distribution about majoraxis.


799— STAAD.Pro

ParameterName

DefaultValue

Description

SFACE 0 Distance from the start node of the beam toface of support for shear design.






10. Beam — Ultimate limit state andService limit state design & Slab —Two-way plate design

11. Beam — Ultimate limit state andService limit state design with tensionstiffening.

12. Beam — Ultimate limit state designonly




801 — STAAD.Pro

Section 20

American Aluminum CodeSTAAD.Pro is capable of performing aluminum member design based on the ASD 1994Specifications for Aluminum Structures, Sixth Edition (October, 1994).

Design of members per ASD 1994 requires the STAAD US Specialized Design CodesSELECT Code Pack.

20A.1 Member PropertiesIn order to do this design in STAAD, the members in the structure must have their propertiesspecified from Section VI of the above-mentioned manual. The section names are mentionedin Tables 5 through 28 of that manual. All of those tables except Table 10 (Wing Channels) andTable 20 (Bulb Angles) are available in STAAD.

Described below is the command specification for various sections:

20A.1.1 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


20A.1.2 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

20A.2 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

20A.2.1 Double angle long leg back-to-back

MEMB-LIST TA LD SECTION-NAME SPACING VALUE

Example

14 TA LD LS4.00X3.00X0.375 SP 1.5

20A.2.2 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

20A.3 Design ProcedureThe design is done according to the rules specified in Sections 4.1, 4.2 and 4.4 on pages I-A-41and I-A-42 of the Aluminum code. The allowable stresses for the various sections arecomputed according to the equations shown in Section 3.4.1 through 3.4.21 on pages I-A-27through I-A-40. The adequacy of the member is checked 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 istermed as RATIO. If the highest RATIO among these equations turns out to be less than orequal to 1.0, the member is declared as having PASSed. If it exceeds 1.0, the member hasFAILed the design requirements.

803— STAAD.Pro

Section 20 American Aluminum Code

Note: The check for torsion per Clause 4.3 for open sections is currently not implementedin STAAD.Pro.

20A.4 Design ParametersThe following are the parameters for specifying the values for variables associated with thedesign.


ParameterName


CODE - Must be specified as ALUMINUM



ALCLAD 0 Defines if material is Alclad.

0 - Material used in thesection is not an Alclad.

1 - Material used in thesection is an Alclad.

ALLOY 34 This variable can take on a value from 1through 40. The default valuerepresents the alloy 6061-T6.

See Table 14A.2 below for a list ofvalues for this parameter and the alloythey represent. Table 3.3-1 in Section I-Bof the Aluminum specificationsprovides information on the propertiesof the various alloys.

Table 20A.1-Aluminum Design Parameters



ParameterName


BEAM 0.0 If this parameter is set to 1.0, theadequacy of the member is determinedby checking a total of 13 equally spacedlocations along the length of themember. If the BEAM value is 0.0, the13 location check is not conducted, andinstead, checking is done only at thelocations specified by the SECTIONcommand (See STAAD manual fordetails). If neither the BEAM parameternor any SECTION command isspecified, STAAD will terminate the runand ask the user to provide one of those2 commands. This rule is not enforcedfor TRUSS members.

DMAX 1000 in. Maximum depth permissible for thesection during member selection. Thisvalue must be provided in the currentunits.

DMIN 0.0 in Minimum depth required for thesection during member selection. Thisvalue must be provided in the currentunits.

KT 1.0 Effective length factor for torsionalbuckling. It is a fraction and is unit-less. Values can range from 0.01 (for acolumn completely prevented fromtorsional buckling) to any user specifiedlarge value. It is used to compute theKL/R ratio for twisting for determiningthe allowable stress in axialcompression.

See Equation 3.4.7.2-6 on page I-A-28 ofthe Aluminum specifications for details.

805— STAAD.Pro


ParameterName


KY 1.0 Effective length factor for overallcolumn buckling in the local Y-axis. Itis a fraction and is unit-less. Values canrange from 0.01 (for a columncompletely prevented from buckling) toany user specified large value. It is usedto compute the KL/R ratio fordetermining the allowable stress in axialcompression.

KZ 1.0 Effective length factor for overallcolumn buckling in the local Z-axis. Itis a fraction and is unit-less. Values canrange from 0.01 (for a columncompletely prevented from buckling) toany user specified large value. It is usedto compute the KL/R ratio fordetermining the allowable stress in axialcompression.

LT Member length 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 user specifiedlarge value. It is used to compute theKL/R ratio for twisting for determiningthe allowable stress in axialcompression. See Equation 3.4.7.2-6 onpage I-A-28 of the Aluminumspecifications for details.

LY Member length Effective length for overall columnbuckling in the local Y-axis. It is inputin the current units of length. Valuescan range from 0.01 (for a columncompletely prevented from buckling) toany user specified large value. It is usedto compute the KL/R ratio fordetermining the allowable stress in axialcompression.



ParameterName


LZ Member length Effective length for overall columnbuckling in the local Z-axis. It is inputin the current units of length. Valuescan range from 0.01 (for a columncompletely prevented from buckling) toany user specified large value. It is usedto compute the KL/R ratio fordetermining the allowable stress in axialcompression.

PRODUCT 1 This variable can take on a value from 1through 4. They represent:

1 - All

2 - Extrusions

3 - Drawn Tube

4 - Pipe

The default value stands for All. ThePRODUCT parameter finds mention inTable 3.3-1 in Section I-B of theAluminum specifications.

SSY 0.0 Factor that indicates whether or not thestructure is subjected to sidesway alongthe local Y axis of the member. Thevalues are:

0 - Sidesway is presentalong the local Y-axis ofthe member

1 - There is no sideswayalong the local Y-axis ofthe member.

The sidesway condition is used todetermine the value of Cm explained inSection 4.1.1, page I-A-41 of theAluminum specifications.

807— STAAD.Pro


ParameterName


SSZ 0.0 Factor that indicates whether or not thestructure is subjected to sidesway alongthe local Z axis of the member. Thevalues are:

0 - Sidesway is presentalong the local Z-axis ofthe member

1 - There is no sideswayalong the local Z-axis ofthe member.

The sidesway condition is used todetermine the value of Cm explained inSection 4.1.1, page I-A-41 of theAluminum specifications.

STIFF Member length Spacing in the longitudinal direction ofshear stiffeners for stiffened flat webs. Itis input in the current units of length.See section 3.4.21 on page I-A-40 of theAluminum specifications forinformation regarding this parameter.

STRUCTURE

1 In Table 3.4-1 in Section I-A of theAluminum specifications, it ismentioned that the value of coefficientsnu, ny and na are dependent uponwhether the structure being designed isa building or a bridge. Users mayconvey this information to STAADusing the parameter STRUCTURE. Thevalues that can be assigned to thisparameter are:

1 - Buildings and similartype structures

2 - Bridges and similartype structures



ParameterName



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 design inaddition to that printedby TRACK 3.

UNL Member length Distance between points where thecompression flange is braced againstbuckling or twisting. This value mustbe provided in the current units. Thisvalue is used to compute the allowablestress in bending compression.

WELD 0 In Table 3.4-2 in Section I-A of theAluminum specifications, it ismentioned that the value of coefficientsKt and Kc are dependent upon whetheror not, the location of the section wheredesign is done is within 1.0 inch of aweld. The WELD parameter is used inSTAAD for this purpose. The values thatcan be assigned to this parameter are:

0 - Region is farther than1.0in from a weld

1 - Region is within 1.0infrom a weld

809— STAAD.Pro


20A.4.1 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

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

Table 20A.2-Alloy Parameters



Value Name

26 5086-H32

27 5086-H34

28 5454-H111

29 5454-H112

30 5456-H111

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

20A.5 Code CheckingThe purpose of code checking is to determine whether the initially specified memberproperties are adequate to carry the forces transmitted to the member due to the loads on thestructure. Code checking is done at the locations specified by either the SECTION commandor the BEAM parameter described above.


Example Problem 1 in the Getting Started and Tutorials Manual for STAAD provides anexample on the usage of the CHECK CODE command.

20A.5.1 Example

Sample input data for Aluminum Design

PARAMETER

CODE ALUMINUM

811 — STAAD.Pro


BEAM 1 ALL

KY 1.2 MEMB 3 4

ALLOY 35 ALL

PRODUCT 2 ALL

TRACK 3 ALL

SELECT ALL

ALCLAD 1 ALL

STRUCT 1 ALL

CHECK CODE ALL

20A.6 Member SelectionThe member selection process involves the determination of the least weight member thatPASSes the code checking procedure based on the forces and moments of the most recentanalysis. The section selected will be of the same type as that specified initially. For example, amember specified initially as a channel will have a channel selected for it.


Example Problem 1 in the Getting Started and Tutorials Manual for STAAD provides anexample on the usage of the SELECT MEMBER command.



813— STAAD.Pro

Section 21

American Transmission Tower Code


815— STAAD.Pro

21A. American Transmission Tower Code - Steel Design perASCE 10-97

STAAD.Pro is capable of performing steel design based on the American Transmission Towercode ASCE 10-97 Design of Latticed Steel Transmission Structures.

Design of members per ASCE 10-97 requires the STAAD US Std Design Codes SELECT CodePack.

21A.1 General CommentsThe ASCE 10-97 code is meant to supercede the older edition of the code, available under thename ASCE Publication 52. However, in the interests of backward compatibility, both codesare currently accessible in STAAD.Pro.

Design is available for all standard sections listed in the AISC ASD 9th edition manual,namely, Wide Flanges, S, M, HP, Tees, Channels, Single Angles, Double Angles, Tubes andPipes. Design of HSS sections (those listed in the 3rd edition AISC LRFD manual) andComposite beams (I shapes with concrete slab on top) is not supported.

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

The detailing requirements, such as provisioning of stiffeners and checking the local effectslike flange buckling, web crippling, etc. must be performed manually. It is assumed that youare familiar with the basic concepts of Steel Design facilities available in STAAD. Please referto Section 2 of the STAAD Technical Reference Manual for detailed information on this topic.

21A.2 Allowable Stresses per ASCE 10-97Member selection and code checking operations in the STAAD implementation of ASCE 10-97are done to resist loads at stresses approaching yielding, buckling, fracture and other limitingconditions specified in the standard. Those stresses are referred to in the standard as DesignStresses. The appropriate sections of the ASCE standard where the procedure for calculatingthe design stresses is explained are as follows.

21A.2.1 Design Axial Tensile Stress

Design tensile stresses are calculated on the basis of the procedure described in section 3.10.The NSF parameter (see the Parameters table shown later in this section) may be used if thesection area needs to be reduced to account for bolt holes.


21A.2.2 Design Axial Compressive Stress

Design compressive stress calculation is based on the procedures of section 3.6 through 3.9. For angle members under compression, the procedures of sections 3.7 and 3.8 have beenimplemented. Capacity of the section is computed for column buckling and whereverapplicable, torsional buckling. The user may control the effective lengths for buckling usingthe LT, LY, LZ and/or KT, KY, KZ parameters (see the Parameters table shown later in thissection).

21A.2.3 Design Bending Compressive Stress

Calculations for design bending compressive stress about the major axis and minor axis arebased on the procedures of section 3.14. Procedures outlined in sections 3.14.1 through 3.14.6have been implemented.

21A.2.4 Design Bending Tensile Stress

Calculations for design bending tensile stress about the major and minor axis are based onthe procedures of section 3.14.2.

21A.2.5 Design Shear Stress

Calculation of the design shear stress is based on the procedure outlined in section 3.15 of theASCE 10-97. The procedure of section 3.15.2 is followed for angles and the procedure of section3.15.1 is followed for all other sections.

21A.3 Critical Conditions used as criteria to determinePass/Fail statusThese are Clause 3.4 for slenderness limits, Clause 3.12 for Axial Compression and Bending,Clause 3.13 for Axial Tension and Bending, Clause 3.9.2 for Maximum w/t ratios and Clause3.15 for Shear.

21A.4 Design ParametersDesign parameters are summarized in the table shown later in this section. These parametersmay be used to control the design process to suit specific modeling needs. The defaultparameter values have been selected such that they are frequently used numbers forconventional design.


817— STAAD.Pro

21A. American Transmission Tower Code - Steel Design per ASCE 10-97

ParameterName


CODE - Must be specified as ASCE to design perASCE 10-97.



BEAM 1.0 0 = Perform design at beam ends andsection locations specified according tothe SECTION command

1 = Perform design at the ends andeleven intermediate sections of the beam

CMY

CMZ

0.85 forsidesway andcalculated forno sidesway

Cm value in local y and z axes as definedin equation 3.12-1 on p.10 of ASCE 10-97.

DMAX 45.0 in. Maximum allowable depth for memberselection

DBL 0.75 in. Diameter of bolt for calculation ofnumber of bolts required and the netsection factor.

DMIN 0.0 in. Minimum allowable depth for memberselection

ELA 4 Indicates what type of end conditions areto be used from among Equations 3.7-4thru 3.7-7 to determine the KL/R ratio.

1. EQN.3.7-4, Page 4

Note: Valid for leg membersonly.

2. EQN.3.7-5, Page 4

3. EQN.3.7-6, Page 4

4. EQN.3.7-7, Page 5

Table 21A.1-Steel Design Parameters for ASCE 10-97


ParameterName


ELB 1 Indicates what type of end conditions areto be used from among Equations. 3.7-8thru 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

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 for warpingrestraint (clause 3.14.4, p. 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 plain angles.

0. indicates that the angle isconnected by both legs andallowable stress in axial tension is1.0FYLD.

1. indicates that the angle isconnected only by the shorter legand allowable tensile stress iscomputed per clause 3.10.2 as0.9FYLD.

2. indicates that the angle isconnected by the longer leg.

LT MemberLength

Effective length for warping.

819— STAAD.Pro


ParameterName


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)

MAIN 2 Parameter that indicates the membertype for the purpose of calculating theKL/R ratio (SEE CLAUSE 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 3C.4, page 31)

5. Redundant member, KL/R ≤ 250

10. Do not perform the KL/R Check

NHL 0 Number of bolt holes on the cross sectionthat should be used to determine the netsection factor for tension capacity.


RATIO 1.0 Permissible ratio that determines the cutoff point for pass/fail status. A valuebelow this quantity indicates PASS whilea value greater than this quantityindicates FAILURE.

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 of allowablestresses

1.0 = Prints all allowable stresses

UNB MemberLength

Unsupported length of the bottom flangefor calculating flexural strength. Will beused only if flexural compression is onthe bottom flange.


ParameterName


UNF 1.0 Same as UNL, but provided as a fraction ofthe member length

UNL MemberLength

Unsupported length of member forcalculation of

allowable bending stress

UNT MemberLength

Unsupported length of the top flange forcalculating flexural strength. Will beused only if flexural compression is onthe top flange.

Note: All values must be provided in the current unit system.

21A.5 Code Checking and Member SelectionBoth code checking and member selection options are available in the ASCE 10-97implementation. In general, it may be noted that the concepts followed in MEMBERSELECTION and CODE CHECKING procedures are similar to that of the AISC based design.



821 — STAAD.Pro


21B. American Transmission Tower Code - Steel Design perASCE Manuals and Reports

STAAD.Pro is capable of performing steel design based on the ASCE Manuals and Reports onEngineering Practice No. 52 – Guide for Design of Steel Transmission Towers, Second Edition

Design of members per ASCE 10-97 requires the STAAD US Std Design Codes SELECT CodePack.

21B.1 General CommentsThe design philosophy and procedural logistics for member selection and code checking isbased upon the principles of allowable stress design. Two major failure modes are recognized:failure by overstressing and failure by stability considerations.

The following sections describe the salient features regarding the process of calculation of therelevant allowable stresses and the stability criteria being used. Members are proportioned toresist the design loads without exceeding the allowable stresses and the most economicalsection is selected based on the least weight criteria. The code checking part of the programalso checks the slenderness requirements, the minimum metal thickness requirements, andthe width-thickness requirements.

The detailing requirements, such as provisioning of stiffeners and checking the local effectslike flange buckling, web crippling, etc. must be performed manually. It is assumed that youare familiar with the basic concepts of Steel Design facilities available in STAAD. Please referto Section 2 of the STAAD Technical Reference Manual for detailed information on this topic.

21B.2 Allowable Stresses per ASCE (Pub. 52)The member design and code checking in the STAAD implementation of ASCE (Pub. 52) isbased upon the allowable stress design method. Appropriate sections of this publication arereferenced below.

21B.2.1 Allowable Axial Tensile Stress

Allowable tensile stresses are calculated on the basis of the procedure described in section 4.10.The NSF parameter (See "Design Parameters" on page 823) may be used if the net section areaneeds to be used.

21B.2.2 Allowable Axial Compressive Stress

Allowable compressive stress calculation is based on the procedures of section 4.6 through 4.9.For angle members under compression, the procedures of sections 4.7 and 4.8 have beenimplemented. Capacity of the section is computed for column buckling and whereverapplicable, torsional buckling. The user may control the effective lengths for buckling usingthe LX, LY, LZ and/or KX, KY, KZ parameters (See "Design Parameters" on page 823).


21B.2.3 Allowable Bending Compressive Stress

Calculations for allowable bending compressive stress about the major axis and minor axis arebased on the procedures of section 4.14. Procedures outlined in sections 4.14.1 through 4.14.6have been implemented.

21B.2.4 Allowable Bending Tensile Stress

Calculations for allowable bending tensile stress about the major and minor axis are based onthe procedures of Section 4.14.2.

21B.2.5 Allowable Shear Stress

Calculation of the allowable shear stress is based on the procedure outlined in section 4.15 ofthe ASCE Pub. 52. The procedure of section 4.15.2 is followed for angles and the procedure ofsection 4.15.1 is followed for all other sections.

21B.2.6 Critical Conditions used as criteria to determinePass/Fail status

These are Clause 4.4 for slenderness limits, Equation 4.12-1 for Axial Compression andBending, Equation 4.13-1 for Axial Tension and Bending, Clause 4.9.2 for Maximum w/t ratiosand Clause 4.15 for Shear.

21B.3 Design ParametersThese parameters may be used to control the design process to suit specific modeling needs. The default parameter values have been selected such that they are frequently used numbersfor conventional design.

ParameterName

DefaultValue

Description

CODE -

Must be specified as ASCE 52.


BEAM 0.0

Specifies locations along member length atwhich member design is deisgned.

2.0 = use the section locations specifiedaccording to the SECTION command3.0 = at the ends and eleven intermediatesections of the beam

DBL 0.75 in.Diameter of bolt for calculation of number ofbolts required and the net section factor.

Table 21B.1-Steel Design Parameters for ASCE (Pub. 52) Based Design

823— STAAD.Pro

21B. American Transmission Tower Code - Steel Design per ASCE Manuals and Reports

ParameterName

DefaultValue

Description

DMAX 45.0 in.Maximum allowable depth for memberselection

DMIN 0.0 in.Minimum allowable depth for memberselection

ELA 4

Indicates what type of end conditions are to beused from among Equations 4.7-4 thru 4.7-7 todetermine the KL/R ratio.

1 = EQN.4.7-4, Page 26 (Valid for legmembers only)2 = EQN.4.7-5, Page 273 = EQN.4.7-6, Page 274 = EQN.4.7-7, Page 27

ELB 1

Indicates what type of end conditions are to beused from among Equations. 4.7-8 thru 4.7-10 todetermine the KL/R ratio.

1 = EQN.4.7-8, Page 27, EQN.4.7-12, Page 282 = EQN.4.7-9, Page 27, EQN.4.7-13, Page 283 = EQN.4.7-10, Page 27, EQN.4.7-14,Page28

FVB 30 KSI Shear strength of bolt.

FYB 36 KSI Yield strength of bolt.

FYLD 36.0 KSI Yield Strength of steel

KT 1.0Effective length coefficient for warping restraint(clause 4.14.4, pg 36)

KY 1.0Effective length factor (K) for compressionbuckling about the Y-axis (minor axis)

KZ 1.0Effective length factor (K) for compressionbuckling about the Z-axis (major axis)

LEG 0.0

This parameter is meant for plain angles.

3.0 = the angle is connected by both legs andallowable stress in axial tension is 1.0·FYLD4.0 = the angle is connected only by theshorter leg and allowable tensile stress iscomputed per Cl. 4.10.2 as 0.9·FYLD5.0 = the angle is connected by the longerleg


ParameterName

DefaultValue

Description

LTMemberLength

Effective length for warping.

LYMemberLength

Length to calculate slenderness ratio forbuckling about the Y-axis (minor axis)

LZMemberLength

Length to calculate slenderness ratio forbuckling about the Z-axis (major axis)

MAIN 2

Parameter that indicates the member type forthe purpose of calculating the KL/R ratio (SeeCl. 4.4, p. 25)

1 = Leg member (KL/r ≤ 150)2 = Compression member (KL/r ≤ 200)3 = Tension member (KL/r ≤ 500)4 = Hanger member per Cl. 4C.4, p. 43 (KL/r≤ 375)5 = Redundant member (KL/r ≤ 250)10 = Do not perform the slenderness (KL/r)check

NHL 0Number of bolt holes on the cross section thatshould be used to determine the net sectionfactor for tension capacity.


RATIO 1.0

Permissible ratio that determines the cut offpoint for pass/fail status. A value below thisquantity indicates PASS while a value greaterthan this quantity indicates FAILURE.

TRACK 0.0

Level of detail in output

0.0 = Suppresses printing of allowablestresses1.0 = Prints all allowable stresses

UNF 1.0Same as UNL, but provided as a fraction of themember length

UNLMemberLength

Unsupported length of member for calculationof allowable bending stress

825— STAAD.Pro

21B. American Transmission Tower Code - Steel Design per ASCE Manuals and Reports

21B.4 Code Checking and Member SelectionBoth code checking and member selection options are available in the ASCE Pub. 52implementation. In general, it may be noted that the concepts followed in MEMBER SELECTIONand CODE CHECKING procedures are similar to that of the AISC based design.




827— STAAD.Pro

Section 22

Steel Design per American Petroleum Institute CodeThe API Steel Design facility in STAAD is based on the API 2A-WSD standard, titledRecommended Practice for Planning, Design and Constructing Fixed Offshore Platforms-Working Stress Design, 21st Edition (December 2000). Joint checks includes “Errata andSupplements” 1, 2 & 3 of the code.

22A.1 Design Operations STAAD contains a broad set of facilities for the design of structural members as individualcomponents of an analyzed structure. The member design facilities provide the user with theability to carry out a number of different design operations. These facilities may be usedselectively in accordance with the requirements of the design problem. The operations toperform 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; and

l Specify design parameters to carry out joint checks.

These operations may be repeated any number of times depending upon the designrequirements.

The basic process is as follows:

1. Define the STAAD model geometry, loading, and analysis.

2. Run the analysis and API design which creates the Geometry file (file extension .PUN)and give preliminary design results.


3. Check and modify the Geometry file as necessary.

4. Re-run the analysis to read the modified Geometry file for the final design results.

22A.1.1 Limitations

The parameter SELECT 1.0 should not be used while carrying out punching shear checks. Itcan be used in initial runs for member selection.

No classification of the joint is performed using the loading. For the initial run of an APIcode check, all joints will be assumed to be a T/Y joint. See "Joint Design" for details.

No hydrostatic checks are performed.

22A.1.2 Truss Members

A truss member is capable of carrying only axial force. So in design, no time is wastedcalculating the allowable bending or shear stresses, thus reducing design time considerably. Therefore, if there is any truss member in an analysis (like bracing or strut, etc.), it is wise todeclare it as a truss member rather than as a regular frame member with both ends pinned.

22A.2 Allowables per API CodeFor steel design, STAAD compares the actual stresses with the allowable stresses as defined bythe American Petroleum Institute (API-RP2A) Code. The 21st edition of API Code, aspublished in 2007, is used as the basis of this design (except for tension stress).

22A.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·Fy

22A.2.2 Shear Stress

Beam Shear Stress

Allowable beam shear stress on the gross section must conform to Clause 3.2.4-2 of theAPI code:

Fv = 0.4·FyThe 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·FyFvt is the maximum torsional shear stress per Clause 3.2.4-3 of the API code.

829— STAAD.Pro

Section 22 Steel Design per American Petroleum Institute Code

22A.2.3 Stress Due to Compression

The allowable compressive stress on the gross section of axially loaded compression members iscalculated based on the formula 3.2.2-1 in the API Code when the largest effective slendernessratio, Kl/r is less than or equal to Cc. If Kl/r exceeds Cc, then the allowable compressive stress isincreased as per formula (3.2.2-2) of the Code.

Where:

=C π2cE

F

2

y

For D/t > 60, the lesser of Fxe or Fxc is substituted for Fxy.

Where:

Fxe = the elastic local buckling stress calculated with C, the critical elasticbuckling coefficient = 0.3 (3.2.2-3)

Fxc = the inelastic local buckling stress. (3.2.2-4)

22A.2.4 Combined Compression and Bending

Members subjected to both axial compression and bending stresses are proportioned to satisfyAPI formula 3.3.1-1 and 3.3.1-2 when fa/Fa > 0.15, otherwise formula 3.3.1-3 applies. It should benoted that during code checking or member selection, if fa/Fa > 1.0, the program does notcompute the second 3.3.1-1/2.

22A.2.5 Bending Stress

The allowable bending stress for tension and compression for a symmetrical member loaded inthe plane of its minor axis, as given in Clause 3.2.3 of the API code, is:

a. When D/t ≤ 1,500/Fy (Imperial Units),

Fb = 0.75Fyb. When 1,500/Fy < D/t ≤ 3,000/Fy (Imperial Units),

Fb = [0.84 - 1.74 FyD/(Et)]Fyc. When 3,000/Fy < D/t ≤ 300 (Imperial Units),

Fb = [0.72 - 0.58 FyD/(Et)]Fy

22A.2.6 Simple Joints: Capacity Checks

A typical joint and the terms involved with the joint checks are given below:



Figure 22A.1 - Simple joint diagram

Definitions

θ = Brace included rage

g = Gap between braces

t = Brace wall thickness at intersection

T = Chord wall thickness at intersection

d = Brace outside diameter

D = Chord outside diameter

β = d/D

γ = D/(2T)

τ = t/T

Joint Validity

The validity range of the joints that are identified will be checked as per Cl. 4.3.1 of the code.The conditions to be checked for each joint are as given below:

0.2 ≤ β ≤ 1.0

10 ≤ γ ≤ 50

30° ≤ θ ≤ 90°

Fy = 90 ksi (500 MPa)

g/D > -0.6 (for K joints)

831 — STAAD.Pro


If any of these conditions are not satisfied for the joint under consideration, the programissuesa warning message corresponding to the invalid parameter(s). The program will, however,perform the joint checks as the code allows for the design of such joints with modified valuesof yield strength. You can use the FYLD parameter to reset the yield strength.

Joint Capacity

The capacity of the joint, both the axial capacity and the moment capacity is

The allowable capacity for brace axial load, Pa, is evaluated as:

=P Q Qa u f

F T

θsin

yc2

FSJ

The allowable capacity for brace bending moment, Ma, is evaluated as:

=M Q Qa u f

F T d

θsin

yc2

FSJ

Where:

Fy = the yield stress of the chord member at the joint (or 0.8 of the tensile stress,if less)

FSJ = the factor of safety parameter (1.6 by default)

Qu and Qf are the strength factor and the Chord factor that are to bedetermined based on the joint type. The strength factor, Qu, is to be determinedas given in Section 4.3.3 of the code (ref. Table. 4.3-1 of the API code).

=

+

−

−

Q C C C A1f

P

P

M

M1 2 3

2c

y

c

y

FSJ FSJ

=

+

AP

P

M

M

2 2

c

y

c

y

FSJ FSJ

Pc = axial load

= +M M Mc ipb opb2 2

C1, C2, and C3 are factors determined by the following table:

Joint Type C1

C2

C3

K joints under brace axial loading 0.2 0.2 0.3

T/Y joints under brace axial loading 0.3 0 0.8

X joints underbraceaxial loading

β ≤ 0.9 0.2 0 0.5

β = 1.0-0.2

0 0.4



Joint Type C1

C2

C3

All joints under brace momentloading

0.2 0 0.4

Note: For values of β between 0.9 and 1.0, coefficients are linearly interpolated betweenlisted values.

For joints that are a mixture of K, X, or Y joints, the capacity of the joint is evaluated as aweighted average of the capacities of each joint.

In case the joint is subjected to combined axial load and bending moments (in-plane and/orout-of-plane), the program performs the following interaction check as given by Cl 4.3.6 ofthe code:

+

+ ≤ 1.0P

P

M

Mipb

M

Mopb

2

a a a

22A.3 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in Table22A.1. These parameters communicate design decisions from the engineer to the program.

The default parameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements for an analysis,some or all of these parameter values may have to be changed to exactly model the physicalstructure. For example, by default the KZ value (k value in local z-axis) of a member is set to1.0, wile in the real structure it may be 1.5. In that case, the KZ value in the program can bechanged to 1.5, as shown in the input instruction (Section 5). Similarly, the TRACK value of amember is set to 0.0, which means no allowable stresses of the member will be printed.


ParameterName


CODE - Must be specified as API



Table 22A.1-American (API) Steel Design Parameters

833— STAAD.Pro


ParameterName


BEAM 1.0 Beam parameter:

0.0 = design only forend moments orthose at locationsspecified by theSECTIONcommand.

1.0 = calculatemoments at twelfthpoints along thebeam, and use themaximum Mzlocation for design.

2.0 = Same forBEAM 1.0, butadditional check ismade at each end.

CB 1.0 Cb value as used in Section 1.5 ofAISC

0.0 = Cb value to be calculated

Any other value will mean thevalue to be used in design

CMY

CMZ

0.85 for sideswayand calculatedfor no sidesway

Cm value in local y & z axes

DMAX 100.0 in Maximum allowable depth

DMIN 0.0 Minimum allowable depth

FSJ 1.6 Factor of safety used for jointchecks.

FYLD 36 ksi Yield strength of steel.

KY 1.0 K value in local y-axis. Typicallythe minor axis.

KZ 1.0 K value in local z-axis. Typicallythe major axis.



ParameterName


LY Member Length Length in local Y-axis to calculateslenderness ratio.

LZ Member Length Length in local Z-axis to calculateslenderness ratio.

MAIN 0.0 Design for slenderness.

1.0 = Main member

2.0 = Secondarymember


RATIO 1.0 Permissible ratio of the actual toallowable stresses

SSY 0.0 Design for sidesway.

0.0 = Sidesway inlocal y-axis

1.0 = No sidesway

SSZ 0.0 Design for sidesway in local z-axis

TRACK 0.0 Controls the level of detail in theoutput:

0.0 = Print designoutput at theminimum level ofdetail.

1.0 = Print all criticalmember stresses

2.0 =

3.0 =

100.0 = Suppress all checks exceptpunching shear

UNF 1.0 Same as above provided as afraction of actual member length

835— STAAD.Pro


ParameterName


UNL Member Length Unsupported length forcalculating allowable bendingstress

WELD 1 Weld type, as explained in section3.1.1 of the API code.

1.0 = Welding is oneside only except forwide flange or teesections, where theweb is alwaysassumed to bewelded on bothsides.

2. 0 = Welding isboth sides. Forclosed sections likepipe or tube, thewelding will be onlyon one side.

WMIN 1.16 in. Minimum thickness

WSTR 0.4 X FLYD Allowable welding stress

Note: The parameters DMAX and DMIN are only used for member selection.

22A.4 Code CheckingThe purpose of code checking is to ascertain whether the provided section properties of themembers are adequate as per API. Code checking is done using the forces and moments atspecific sections of the members. If no sections are specified, the program uses the start andend forces for code checking.

When code checking is selected, the program calculates and prints whether the members havepassed or failed the checks, the critical condition of API code (like any of the APIspecifications for compression, tension, shear, etc.), the value of the ratio of the criticalcondition (overstressed for value more than 1.0 or any other specified RATIO value), thegoverning load case, and the location (distance from the start of the number of forces in themember) where the critical condition occurs.

Code checking can be done with any type of steel section listed in Section 2.2 of the TechnicalReference manual.




22A.5 Member SelectionThe program is capable of performing design operations on specified members. Once ananalysis has been performed, the program can select the most economical section, i.e., thelightest section which fulfills the code requirements for the specified member. The sectionselected will be of the same type section as originally designated for the member beingdesigned. Member selection can also be constrained by the parameters DMAX and DMIN whichlimits the maximum and minimum depth of the members.

l Member selection can be performed with all types of hollow steel sections.

l Selection of members whose properties are originally input from a user created tablewill be limited to sections in the user table.

l Member selection cannot be performed on members whose section properties are inputas prismatic.


22A.6 Chord Selection and Qf ParameterQf is a factor to account for the presence of nominal longitudinal stress in the chord. Whencalculating Qf for the joints, the moments used in the chord stress calculation will be fromthe computer node results and not the representative moments underneath the brace. If themoment varies significantly along the chord, it is more accurate to use the actual chordmoment in the middle of the brace foot print. The tests reported in Reference I[1] wereperformed with a constant moment along the chord. Thus for a local joint check, the localchord moment (under the brace) should be used.

STAAD calculates Qf based on the moment at the chord member. The chord member can beselected automatically by initial screening by the program (based on geometry andindependent of loading) or specified in the External file.

In the automatic selection of the chord two collinear members (5 degree tolerance) are usedto identify the chord. The chord is then selected from one of the two members based on thelarger diameter then thickness or then by the minimum framing angle; for T joints the firstmember 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.

22A.6.1 Reference

1 Ref I: Boone, TJ. Yura, JA. and Hoadley, PW. Ultimate Strength if Tubular Joints – ChordStress Effects, OTC 4828, 1984

837— STAAD.Pro


22A.7 Tabulated Results of Steel DesignFor code checking or member selection, the program produces the results in a tabulatedfashion. The items in the output table are explained as follows:

Memberthe member number for which the design is performed.

TABLEAISC steel section name which has been checked against the steel code or has beenselected.

RESULTSprints whether the member has PASSed or FAILed. If the RESULT is FAIL, therewill be an asterisk (*) mark on front of the member.

CRITICAL CONDthe section of the AISC code which governs the design.

RATIOprints the ratio of the actual stresses to allowable stresses for the critical condition. Normally a value of 1.0 or less will mean the member has passed.

LOADINGprovides the load case number which governed the design.

FX, MY, and MZprovide the axial force, moment in local Y-axis, and the moment in local Z-axisrespectively. Although STAAD does consider all the member forces and moments(except torsion) to perform design, only FX, MY and MZ are printed since they arethe ones which are of interest, in most cases.


Note: If the parameter TRACK is set to 1.0, the program will block out part of the table andwill print the allowable bending stressed in compression (FCY & FCZ) and tension(FTY & FTZ), allowable axial stress in compression (FA), and allowable shear stress(FV).

22A.7.1 Example of Member Code Check output

For TRACK 0.0 output:

STAAD.Pro CODE CHECKING - (API )***********************

PROGRAM CODE REVISION V21_API_2000/1



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

6 ST PIP40610.0 (BRITISH SECTIONS)PASS API 3.3.1-2 0.024 2



2.76 T 0.00 5.12 3.007 ST PIP40610.0 (BRITISH SECTIONS)

PASS API 3.3.1-3 0.078 298.14 C 0.00 5.12 0.00

For TRACK 1.0 or TRACK 2.0 output:

14 ST PIP1938.0 (BRITISH SECTIONS)PASS API 3.3.1-3 0.130 2

67.16 C 0.00 0.29 4.24|-------------------------------------------------------------------------|| MEMB= 14, UNIT NEW-MMS ,L= 4243. AX= 4670. SZ= 208157. SY= 208157.|| KL/R-Y= 64.6 CB= 1.00 YLD= 248.21 ALLOWABLE STRESSES: FCZ= 186.2 || FTZ= 186.2 FCY= 186.2 FTY= 186.2 FA= 117.6 FT= 148.9 FV= 99.3 ||-------------------------------------------------------------------------|

22A.7.2 Example of Joint Check output


STAAD.Pro - API JOINT CHECKS TO 21st edition.---------------------------------------------------

NODE NO: 7 CHORD NO: 7 BRACE NO: 10 RATIO: 0.049 PASSNODE NO: 7 CHORD NO: 7 BRACE NO: 13 RATIO: 0.245 PASSNODE NO: 7 CHORD NO: 11 BRACE NO: 14 RATIO: 0.222 PASS


STAAD.Pro - API JOINT CHECKS TO 21st edition.---------------------------------------------------

======================================================================NODE NO : 7 CHORD NO: 7 BRACE NO: 13======================================================================DESIGN DATA : (Units : N , mm )Chord Memb : D = 406.40 T = 10.01Brace Memb : d = 193.70 t = 8.00Angle (THETA) = 45.0 deg GAP = 50.80 Fyc = 248.2BETA = 0.48 GAMMA = 20.30 TAU = 0.80

JOINT CLASS : X + Y Contributions: 0.% K, 50.% X, 50.% Y

Factors are not displayed for TRACK 1.0 outputFACTORS :---------------------------------------

-----------------------------Joint Load Strength Chord Load C1 C2 C3Class Cond factor (Qu) factor (Qf)--------------------------------------------------------------------X AX 10.962 0.988 0.200 0.000 0.500Y AX 14.299 0.983 0.300 0.000 0.800X IPB 7.896 0.989 0.200 0.000 0.400Y IPB 7.896 0.989 0.200 0.000 0.400

----------------------------------------------------------------------CAPACITY CHECKS BRACE LOAD LC CAPACITY RATIO STATUS

(Cl. 4.3) (KN, m ) (KN, m )----------------------------------------------------------------------AXIAL : 66.995 2 273.398 0.245 PASSIP BENDING : 0.080 2 33.228 0.002 PASSINTERACTION : 2 0.245 PASS

839— STAAD.Pro


----------------------------------------------------------------------CRITICAL : 2 0.245 PASS----------------------------------------------------------------------

22A.8 Joint Design

22A.8.1 Joint Checking

The design of joints is based on Section 4 of the API code.

The program only checks simple joints and overlapping joints formed between circular hollowsection members. Any other type of joint within the structure or joint cans will not beconsidered for API joint checks. Other types of joints (such as grouted joints, joints with ringstiffeners, etc.) are not considered.

Material Strength

The API code states in Cl. 4.2.1 that the value of yield stress of the chord member to be used inthe calculation of the joint capacity should be limited to 0.8 times the tensile strength of thechord for materials with a yield stress less than or equal to 500 MPa.

The yield stress to be used in the joint capacity checks value is specified in the joint data file(filename.PUN). For every joint, the value specified in the FYLD column will be used as theyield strength to be used for the joint capacity checks. When the file is created for the firsttime by the program, a default value of 36 ksi is used for all joints. The value used for eachjoint check will also be reported in the output file.

Note: All the fields in the joint data file (*.PUN file) are to be in imperial units.

Minimum Joint Capacity

Clause 4.2.3 of the code specifies a minimum capacity for any joint as follows:

The connections at the ends of a member should develop the strength required by the designloads, but should not be less than 50% of the effective strength of the member. The effectivestrength is defined as the buckling load for a compression member or the yield load formembers in tension. You, however, must ensure that this condition is satisfied even if thejoint strength indicates a PASS status.

The program checks to see if the capacity of a joint as calculated by the methods in the codesatisfies this requirement. If not the program issues a warning to that effect and marks thejoint as FAILED. The program calculates the axial and/or bending moment capacities of thejoint and reports the load/capacity ratio for each condition. The program also reports a ‘criticalratio’ along with the condition that induces this ratio. Note that the maximum among thevarious individual ratios will be reported as the ‘critical ratio’. The program also reports aPASS/FAIL status for the joint.

See "Simple Joints: Capacity Checks" for details of capacity checks performed.



Joint Classification

Clause of 4.2.4 of the API code essentially classifies a joint into one of the three basic types: K,X, and Y. Joint classification is the process whereby the axial load in a given brace issubdivided into its K, X, and Y components corresponding to the three joint types. A joint—as considered in the code—is the connection between a "chord" and a "brace" that are in thesame plane. The program considers any two members to be in the same plane if they lie inplanes that are within ±15 degrees of each other. The classification of a joint can also be amixture of any of the basic types mentioned above. Once the classification of a joint has beenidentified, the capacity of that joint is then evaluated per Section 4.3 of the code.

The program automatically identifies the joints in a structure and identifies the chord andthe brace members. The program applies the ±15° rule to determine the members in a planeand then determines the joint as being the intersection point of these members. Since a jointis between a chord and a brace member, the program considers two members at a time andthen proceeds to identify the chord and the brace member at that joint. The programassumes the member with the larger diameter among the two members as the chord memberand the other is considered as the brace. If both members have the same diameter, the chordis assumed to be the member with the thicker wall. If both the diameter and thickness of themembers are identical, the program will assume the most horizontal member to be thechord. To be automatically considered as a chord member, the member has to be continuousacross the joint. The user can always edit the joint data file (*.PUN) to add or delete newBRACE-CHORD joints.

The chord and brace member numbers (from the STAAD input file) are saved under theCHORD and BRACE columns in the filename.PUN file.

When the joint data file (.PUN) is created by the program, a default joint Class Y is assumedfor the initial joint checks. This is indicated by the K, X, and Y column values being set to 0,0, and 1 respectively. Since the API code allows for a mixed joint classification, you mustmanually vary the contribution factors for K, X, and Y joint classes for a given joint. Forexample, if a joint is to be 25% K, 25% X, and 50% Y, then you must assign K column value of0.25, X column value of 0.25, and a Y column value of 0.50 for that joint. The program willverify that the supplied contributions sum to 1.0.

If the joint has a gap (i.e., a K-GAP joint), the gap distance (in inches) must be supplied inthe GAP column. The value to be provided will be the actual gap between the brace membersat the joint. An overlap can be specified by setting the gap to a negative value. Theoverlapping brace in this case can then be indicated by specifying the member number at theOBRACE (Overlapping brace) column in the data file.

Overlapping Joints

Clause 4.4 of the API discusses overlapping joints. Checks for overlapping joints will beperformed as described Section 22A.2.6. The difference will be in that the gap value, g, will betaken as negative in evaluating the various factors.

841 — STAAD.Pro


If the axial loads in the overlapping brace and the through brace have the same sign, the axialload in the through brace will be increased to allow for the loads in the overlapping brace.This will be achieved by allowing a portion of the overlapping brace load equal to theproportion of the overlapping brace area to be added to the axial load in the through brace.

Note: The program issues a warning for any joint overlap is less than 0.25·β·D.

22A.8.2 Joint File Format

The data contained in the filename.PUN file should meet the following format. The overallprocess of performing punching shear checks consists of two steps which are explained inSection 22A.2.6.

When the API design module is invoked, the program will initially check for the presence of afilename.PUN file (where filename is the name of the .std file) in the same folder as theinput file. If the program does not find such a file, it assumes that the joint design is beingrun for the first time and will create this file. If the program does find this file, it will assumethat the joint design has been run at least once and will attempt to read the input data fromthis file. Not that modifying and saving the main structure (i.e., any changes to the mainmodel using GUI or text editor) will invalidate all design results and the program willautomatically delete all design related files including the *.PUN file. Hence if the user wises tokeep an existing version of the *.PUN file, he/she must make a separate copy of this file beforemaking any changes to the model.

Note: Units used in this file must be kips and inches.

General Format

*BRACE CHORD K X Y D T d t GAP FYLD OBRACE TW SWAP

b# c# K% X% Y% Dc Tc db tb gap fy ob tw swap

Where:

b# = the brace member number

c# = the chord member number

K%, X%, and Y% = The fractional contributions of K-type, X type and Y-type,respectively. Initially the joints will be classed as Y (i.e., K=0, X=0 and Y=1).

db, tb = Diameter and thickness of BRACE member

Dc, Tc = Diameter and thickness of CHORD member

gap = Distance required to calculate gap factor for K bracing. Initially, the valueof GAP is assumed as 0. An overlap can be specified by setting the gap to anegative value.

fy = the yield stress to be used in the joint capacity checks



ob = member number of the overlapping brace in an overlap joint (i.e., a gapvalue less than zero)

tw = Used in overlap K-joint, taken as the lesser of the weld throat thickness orthickness t of the thinner brace in inches

swap = If parameter SWAP 0 is used then major moment Mz is taken for InPlane Bending (IPB). SWAP 1 uses the minor moment My as the IPB.

Example

*BRACE CHORD K X Y D T DT GAP FYLD OBRACE TW SWAP10 7 0.000 0.000 1.000 16.000 0.394

16.000 0.394 0.00 36.0 0.0 0.00 013 7 0.000 0.000 1.000 16.000 0.394

7.626 0.315 0.00 36.0 0.0 0.00 014 11 0.000 0.000 1.000 16.000 0.394

7.626 0.315 0.00 36.0 0.0 0.00 0

843— STAAD.Pro


Section 23

ANSI/AISC N690 Design Codes


845— STAAD.Pro

23A. ANSI/AISC N690-1994 CodeSTAAD.Pro is capable of performing steel design based on ANSI/AISC N690-1994 and asamended by Supplement No. 2 to the Specification of the Design, Fabrication and Erection ofSteel Safety-Related Structures for Nuclear Facilities (ANSI/AISC N690 1994(R2004)s2).

Design of members per ANSI/AISC N690-1994 requires the STAAD Nuclear Design CodesSELECT Code Pack.

23A.1 General CommentsFor steel design, STAAD compares the actual stresses with the allowable stresses as defined byANSI/AISC N690-1994 and as amended by ANSI/AISC N690 1994(R2004)s2.

All the design steps are done as described in section 2.3 Allowable per AISC-ASD (NinthEdition) Code of Technical Reference manual except for allowable stress in compression forAUSTENlTlC STAINLESS STEEL. Section Q1.5.9 is used to calculate allowable compressive stressfor Austenitic Stainless Steel. Correction made in Supplementary s1 published in April 15, 2002has been applied.

Note: By default, N690 code uses Stainless Steel material in the design. Care should betaken to assign the proper Stainless Steel material properties to the members for theanalysis. There is a parameter – STYPE – to change material type to either StainlessSteel (STYPE=1) or Carbon Steel (STYPE=0).

23A.1.1 Design Process

Members subjected to both axial compression and bending stresses are proportioned to satisfyequation Q1.6-1a:

+ + ≤⋅ ⋅

−

⋅

− ′ ′

1.0SFC f

F

SMY C f

F

SMZ C f

F1 1

a

a

my by

by

fa

F ey

mz bz

bz

fa

F ez

and Q1.6-1b:

+ + ≤⋅ ⋅ ⋅1.0

SFC f

F

SMY f

F

SMZ f

F0.6

a

y

by

by

bz

bz

when, fa/Fa > 0.15, as per section Q1.6.1 of the code.

Otherwise, equation Q1.6-2 must be satisfied:

+ + ≤⋅ ⋅ ⋅1.0

SFC f

F

SMY f

F

SMZ f

F

a

a

by

by

bz

bz

It should be noted that during code checking or member selection, if fa/Fa exceeds unity, theprogram does not compute the second and third part of the formula, because this wouldresult in a misleadingly liberal ratio. The value of the coefficient Cm is taken as 0.85 for side-sway and [0.6 - 0.4·(M1/M2)], but not less than 0.4 for no side-sway.


Members subjected to both axial tension and bending stress are proportioned to satisfyequation Q1.6-3:

+ + ≤⋅ ⋅ ⋅1.0

SFT f

F

SMY f

F

SMZ f

F0.6

a

y

by

by

bz

bz

Where:

SFC, SFT, SMZ, and SMY are stress limit coefficient parameters used to control thecomponents of the interaction equations. Refer to Table 23A.1 for details.

23A.2 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in thefollowing table.

The default parameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements for an analysis,some or all of these parameter values may have to be changed to exactly model the physicalstructure

ParameterName

DefaultValue

Description

CODE - Must be specified as AISC N690



BEAM 1 Beam parameter

0. Perform design at ends and thoselocations in theSECTION command.

1. Perform design at ends and at1/12th section locations along themember length.

Table 23A.1-Design Parameters for ANSI/AISC N690-1994

847— STAAD.Pro

23A. ANSI/AISC N690-1994 Code

ParameterName

DefaultValue

Description

CAN 0 Used for Deflection Check only (i.e., whenDFF is specified).

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 dependent uponmoment gradient, as specified in ChapterF of AISC ASD.

0.0 = CB is calculated itself

Any other user-defined value is accepted.

CMY

CMZ

0.85 forsideswayand

calculatedfor nosidesway


COMPOSITE 0 Composite action with connectors (CMP)

0. No composite action

1. Composite action

2. Ignore positive moments duringdesign

CONDIA 0.625 in Diameter of shear connectors (DIA), incurrent units.

CONHEIGHT 2.5 in Height of shear connectors after welding(HGT), in current units.

CYCLES 500,000 Cycles of maximum stress to which theshear connector is subject (CYC).


ParameterName

DefaultValue

Description

DFF None(Mandatory

fordeflectioncheck)



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 hardens to thetotal moment (DR2).

DLRATIO 0.4 Ratio of moment due to dead loadapplied before the concrete hardens to thetotal moment (DR1).

DMAX 45 inch Maximum allowable depth

DMIN 0.0 inch Minimum allowable depth

EFFWIDTH 1/4 MemberLength

Effective width of concrete slab (WID).

FYLD 36 KSI Yield strength of steel in current units.

FPC 3 KSI Compressive strength of concrete at 28days, in current units.

FSS 1 Full section shear for welding.

0. False

1. True

FU 60 KSI Ultimate tensile strength of steel, incurrent units.

FYLD 46 KSI Yield strength of steel, in current units.

KX 1.0 Effective length factor for flexuraltorsional buckling.

KY 1.0 Effective Length Factor for Compressionin local y-axis. Usually, this is minor axis.

849— STAAD.Pro


ParameterName

DefaultValue

Description

KZ 1.0 Effective Length Factor for Compressionin local z-axis. Usually, this is major axis.

LX MemberLength

Length for flexural torsional buckling.

LY MemberLength

Length to calculate slenderness ratio(KL/r) for 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 tension members

OVR 1.0 Factor by which all allowablestresses/capacities should be multiplied.Default of 1.0 indicates that nooverstressing is allowed.

PLTHICK 0 Thickness of the cover plate welded to thebottom flange of the composite beam(PLT), in current units.

PLTWIDTH 0 Width of the cover plate welded to thebottom flange of the composite beam(PLT), in current units.

PROFILE None Used to search for the lightest section forthe profile(s) specified for memberselection. See Section 5.48.1 of theTechnical Reference Manual for details.


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 compression(SLC) as found in Table Q 1.5.7.1.


ParameterName

DefaultValue

Description

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 shear stressusing VQ/It

1. Computes the actual shear stressusing V(Ay or Az)

SHORING 0 Temporary shoring during construction

0. Without shoring

1. With shoring

SLABTHICK 4 in Thickness of concrete slab or thickness ofconcrete slab above the form steel deck(THK), in current units.

SMY 1.0 Stress limit coefficient for minor axisbending (SLC) as found in Table Q 1.5.7.1.

SMZ 1.0 Stress limit coefficient for major axisbending (SLC) as found in Table Q 1.5.7.1.

SSY 0 Design for sidesway in the local y axis.

0. Sidesway

1. No sidesway

SSZ 0 Design for sidesway in the local z axis.

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

851 — STAAD.Pro


ParameterName

DefaultValue

Description

TAPER 1 Design for tapered member.

0. Design for tapered I-section basedon rules in Chapter F andAppendix B.

1. Design for tapered section based onAppendix 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 allowable bendingcompressive stress. Will be used only ifflexural compression on the bottomflange.

UNT MemberLength

Unsupported length of the top* flange forcalculating allowable bending compressivestress. Will be used only if flexuralcompression on the top flange.

WELD 1 Design for weld.

0. Closed sections.

1. Open sections.

WMAX 1 in Maximum weld thickness, in currentunits.


ParameterName

DefaultValue

Description

WMIN 0.625 in Minimum weld thickness, in currentunits.

WSTR 0.4·Fyld Allowable welding stress, in current units.

23A.2.1 Notes

1. All values are entered in the current units

2. parameters DMAX and DMIN are only used with the MEMBER SELECTION command

23A.3 ExamplesThese example problems are included for the verification of design results.

23A.3.1 Example 1

This example is included as C:\SProV8i\STAAD\Examp\N690\N690_case1.std

Solution

Allowable Compressive Stress:

Maximum Slenderness Ratio, (Kl/r)max = 171.31

Yield Stress of Steel, Fy = 36 ksi

Cc = [(2π2E)/Fy]1/2 = 127.68

Allowable Compressive Stress for Austentic Stainless Steel, As,

(Kl/r)max > CcFa = (12π2E)/[23(Kl/r)max] = 5.21 ksi

Comparison

Value of Reference STAAD.Pro Difference

Fa (ks) 5.21 5.22 Negligible

Table 23A.2-ANSI-AISC N690-1994 Code VerificationProblem 1

Input File

STAAD SPACE


ENGINEER DATE 30-NOV-07

853— STAAD.Pro


END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 4 0 0;

MEMBER INCIDENCES

1 1 2;


ISOTROPIC STEEL

E 2.05E+008

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


1 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 PINNED

2 FIXED BUT FX MY MZ


MEMBER LOAD

1 CON GY -10 2

UNIT METER KIP

UNIT METER KN


JOINT LOAD

2 FX -1

LOAD COMB 3 COMBINATION LOAD CASE 3

1 1.0 2 9.5


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)= 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 |

855— STAAD.Pro


| 2.14 C 0.00 -7.38 6.56 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|

23A.3.2 Example 2


Solution




Cc = [(2π2E)/Fy]1/2 = 127.68


(Kl/r)max < 120.0

Fa = (Fy/2.15) - [(Fy/2.15) - 6.0]/120.0x(Kl/r)max = 9.07 ksi

Comparison


Fa (ks) 9.07 9.08 Negligible


Input File

STAAD SPACE



END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

3 0 0 1; 4 2 0 1;

MEMBER INCIDENCES

2 3 4;


ISOTROPIC STEEL

E 2.05E+008


POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


2 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

3 PINNED



MEMBER LOAD

UNIT METER KIP

2 CON GY -2.24809 1

UNIT METER KN


JOINT LOAD

4 FX -1


1 1.0 2 9.5



UNIT METER KIP

PARAMETER 1

CODE AISC N690

TRACK 2 ALL

CHECK CODE ALL

FINISH

Output



|--------------------------------------------------------------------------|| Y PROPERTIES ||************* | IN INCH UNIT || * |=============================| ===|=== ------------ ||MEMBER 2 * | AISC SECTIONS | | AX = 3.55 || * | ST W6X12 | | --Z AY = 1.25 |

857— STAAD.Pro


|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 || || 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 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|

23A.3.3 Example 3


Solution





Cc = [(2π2E)/Fy]1/2 = 127.68


120.0 < (Kl/r)max < CcFa = Fy[0.4 - (1/600)x(Kl/r)max] = 7.08 ksi

Comparison


Fa (ks) 7.08 7.08 None


Input File

STAAD SPACE



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;


ISOTROPIC STEEL

E 2.05E+008

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


1 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

859— STAAD.Pro


1 PINNED



MEMBER LOAD

1 CON GY -10 2

UNIT METER KIP

UNIT METER KN


JOINT LOAD

2 FX -1


1 1.0 2 9.5



UNIT METER KIP

PARAMETER 1

CODE AISC N690

TRACK 2 ALL

CHECK CODE ALL

FINISH

Output



|--------------------------------------------------------------------------|| 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 ||--------------- + 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 ||* *||**************************************************************************|| ||--------------------------------------------------------------------------|

861 — STAAD.Pro


23B. ANSI/AISC N690-1984 Code

23B.1 General CommentsFor code checking of steel members, STAAD compares the actual stresses with the allowablestresses as defined by the "ANSI/AISC N690-1984: Nuclear Facilities - Steel Safety-RelatedStructures for Design, Fabrication, and Erection."

A brief description of some of the major allowable stresses is described herein.

23B.2 Design ProcessThe following Checks are to be performed on a Steel Member as per this AISC N690 – 1984Code. When a design is performed, the output file the reports the maximum utilization fromall of the checks.

23B.2.1 Slenderness

The maximum allowable slenderness ratio in Compression (K·L/r_min), as per clause Q1.8.4 ofthe code shall not exceed 200. And the maximum allowable slenderness ratio in Tension (L/r_min) shall not exceed 240 for main members and 300 for bracing members and othersecondary members.

This can be controlled by using the existing MAIN and TMAIN parameters respectively.

The default value of MAIN is 200 and for TMAIN is 240.

23B.2.2 Check for Element Slenderness and Stress ReductionFactors

The permissible Width-to-Thickness Ratio of “Un-stiffened Elements under Compression” isdetermined as per section Q1.9.1 and that of “Stiffened Elements under Compression” isdetermined as per section Q1.9.2 of the code.

The permissible Width–Thickness Ratio of web is determined as per section Q1.10.2.

23B.2.3 Tension

Allowable tensile stress on the Net section is calculated as 0.60·Fy, but not more 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 NSF parameter canbe utilized for that.

The Effective Net Area (Ae) of axially loaded tension members, where the load is transmittedby bolts through some but not all of the cross-sectional elements of the member, shall becomputed from the formula (ref. Q1.14),

Ae = Ct·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 not implemented inSTAAD.

23B.2.4 Compression

The allowable compressive stress for columns which meet the provisions of section Q1.9,except those fabricated from austenitic stainless steel shall be as required by Q1.5.1.3. Theallowable compressive stress for columns fabricated from austenitic stainless steel shall be inaccordance to section Q1.5.9.

A. Gross Sections of Columns, except those fabricated of austenitic stainless steel:

1. On gross section of axially loaded compression members, when (Kl/r) ≤ Cc,

Fa = [1 - (Kl/r)2/(2·Cc2)]Fy / 5/3 + [3(Kl/r)/(8·Cc)] - [(Kl/r)

3/(8·Cc3)]

Where:

Cc = [(2·π2E)/Fy]1/2

2. When (Kl/r) > Cc,

Fa = 12·π2E/[23(kL/r)2]

B. Gross sections of columns fabricated from Austenitic Stainless steel:

1. When (Kl/r) ≤ 120,

Fa = Fy/2.15 - [(Fy/2.16 - 6)/120](kL/r)

2. When (Kl/r) > 120,

Fa = 12 - (KL/r)/20

If the provisions of the section Q1.9 are not satisfied,

A. For un-stiffened compression element, a reduction factor Qs is introduced. Detailedvalues of Qs for different shapes are given in Section QC2.

B. For stiffened compression element, a reduced effective width be is introduced.

1. For the flanges of square and rectangular sections of uniform thickness:

be = 253·t/√Fy1 - (50.3/[(b/t)√Fy] ≤ b

2. For other uniformly compressed elements:

be = 253·t/√Fy1 - (44.3/[(b/t)√Fy] ≤ b

Consequently, a reduction factor Qa is introduced and is equal to the effectivearea divided by the actual area. Combining both these factors, allowable stressfor axially loaded compression members containing stiffened or unstiffenedelements shall not exceed

Fa = QsQa[1 - (Kl/r)2/(2·Cc

2)]Fy / 5/3 + [3(Kl/r)/(8·Cc)] - [(Kl/r)3/(8·Cc

3)]

863— STAAD.Pro


Where:

C'c = [(2·π2E)/(QsQaFy)]1/2

23B.2.5 Bending Stress

Allowable bending stress for tension and compression for a structural member, as given insection Q1.5.1.4 is:

A. Along Major Axis:

1. Tension and compression on extreme fibers of compact hot rolled or built-upmembers symmetrical about and loaded in the plane of their minor axes andmeeting the requirements of Subsection Q1.5.1.4.1.1 to 7, shall result in amaximum bending stress:

Fb = 0.66·FyIf meeting the requirements of this member of:

a. Width-thickness ratio of unstiffened projecting elements of thecompression flange shall not exceed 65/√Fy.

b. Width-thickness ratio of stiffened elements of the compression flangeshall not exceed 190/√Fy.

c. The depth-thickness ratio of the web shall not exceed

d/t = (640/√Fy)[1 – 3.74(fa/Fy)] when fa/Fy ≤0.16

d/t = 257/√Fy when fa/Fy > 0.16

d. The laterally unsupported length of the compression flange of membersother than box-shaped members shall not exceed the value of 76bf/√Fy nor20000/(d/Af)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·FyB. Along Minor Axis:

1. For doubly symmetrical members (I shaped) meeting the requirements of sectionQ1.5.1.4.1, maximum tensile and compressive bending stress shall not exceed thefollowing value as per section Q1.5.1.4.3:

Fb = 0.75·Fy2. For doubly symmetrical members (I shaped) meeting the requirements of section

Q1.5.1.4.1, except where bf/2tf > 65/√Fy but is less than 95/√Fy, maximum tensileand compressive bending stress shall not exceed:

Fb = Fy[0.79 – 0.002(bf/2tf)√Fy]


23B.2.6 Combined Interaction Check

Members subjected to both axial compression and bending stresses are proportioned to satisfyequation Q1.6-1a:

SFC·fa/Fa + SMY·Cmyfby/[(1 - fa/F'ey)Fby] + SMZ·Cmzfbz/[(1 - fa/F'ez)Fbz] ≤ 1.0

and Q1.6-1b

SFC·fa/(0.6·Fy) + SMY·fby/Fby + SMZ·fbz/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·fby/Fby + SMZ·fbz/Fbz ≤ 1.0

It should be noted that during code checking or member selection, if fa/Fa exceeds unity, theprogram does not compute the second and third part of the formula, because this wouldresult in a misleadingly liberal ratio. The value of the coefficient Cm is taken as 0.85 for side-sway and [0.6 - 0.4·(M1/M2)], but not less than 0.4 for no side-sway.

Members subjected to both axial tension and bending stress are proportioned to satisfyequation Q 1.6-1b:

SFT·fa/(0.6·Fy) + SMY·fby/Fby + SMZ·fbz/Fbz ≤ 1.0

Where SFC, SFT, SMZ, and SMY are stress limit coefficient parameters used to control thecomponents of the interaction equations. Refer to Table 17B.1 for details.

23B.2.7 Shear Stress

Allowable shear stress on the gross section [ref. section Q1.10.5.2] is calculated as

Fv = (Fy/2.89)Cv ≤ 0.4·FyWhere:

Cv = (45,000·k)/[Fy(h/t)2], when h/t ≤ 0.8

Cv = [190/(h/t)]√(k/Fy), when h/t > 0.8

k = 4.00 + [5.34/(a/h)2], when a/h ≤ 1.0

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 total depth andthe web thickness. For shear on the flanges, the gross section is taken as the total flange areas.

23B.3 Member Property SpecificationFor specification of member properties, the specified steel section available in Steel SectionLibrary of STAAD may be used, namely: I-shaped section, Channel, Tee, HSS Tube, HSS Pipe,Angle, Double Angle, and Double Channel sections.

865— STAAD.Pro


Member properties may also be specified using the User Table facility except for the Generaland Prismatic member.


23B.4 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in thefollowing table.

The default parameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements for an analysis,some or all of these parameter values may have to be changed to exactly model the physicalstructure

ParameterName

DefaultValue

Description

CODE - Must be specified as AISC N690 1984 to usethe ANSI/AISC N690-1984 code for checkingpurposes.



CAN 0 Used for Deflection Check only.

0 = Deflection check based onthe principle that maximumdeflection occurs within thespan between DJ1 and DJ2.

1 = Deflection check based onthe principle that maximumdeflection is of the cantilevertype

CB 1.0 Bending coefficient dependent upon momentgradient



Table 23B.1-Design Parameters for ANSI/AISC N690-1984


ParameterName

DefaultValue

Description

CMY

CMZ

0.85 forsideswayand



CT 0.75 Reduction Coefficient in computing neteffective net area of an axially loaded tensionmember.

DFF None(Mandatory

fordeflectioncheck)





Joint No. denoting end point for calculationof "Deflection Length"



FU 60 KSI Ultimate tensile strength of steel in currentunits.

FYLD 36 KSI Yield strength of steel in current units.

KY 1.0 Effective Length Factor for Compression inlocal y-axis. Usually, this is minor axis.

KZ 1.0 Effective Length Factor for Compression inlocal z-axis. Usually, this is major axis.

LY MemberLength

Length to calculate slenderness ratio forbuckling about local Y axis.

LZ MemberLength


MAIN 0.0 Design for slenderness.

0. Check for slenderness

1. Suppress slenderness check

867— STAAD.Pro


ParameterName

DefaultValue

Description

NSF 1.0 Net section Factor for tension members

PROFILE None Used to search for the lightest section for theprofile(s) specified for member selection. SeeSection 5.48.1 of the Technical ReferenceManual for details.


SFC 1.0 Stress limit coefficient for compression (SLC)as found in Table Q 1.5.7.1.

SFT 1.0 Stress limit coefficient for tension (SLC) asfound in Table Q 1.5.7.1.

SMY 1.0 Stress limit coefficient for minor axis bending(SLC) as found in Table Q 1.5.7.1.

SMZ 1.0 Stress limit coefficient for major axis bending(SLC) as found in Table Q 1.5.7.1.


whichever isgreater

Spacing of stiffeners for plate girder design

STYPE 0.0 0.0 = Normal Steel

1.0 = Austenitic Stainless Steel

TMAIN 240 formainmember

300 for“Truss”member


TRACK 0.0 Controls the levels of detail to which resultsare reported.

0 = Minimum detail

1 = Intermediate detail level

2 = Maximum detail


ParameterName

DefaultValue

Description

UNB MemberLength

Unsupported length of the bottom* flangefor calculating allowable bending compressivestress. Will be used only if flexuralcompression on the bottom flange.

UNT MemberLength


23B.4.1 Notes

1. All values are entered in the current units

2. parameters DMAX and DMIN are only used with the MEMBER SELECTION command

23B.5 Code Checking and Member SelectionBoth code checking and member selection options are available with the AISC N690 1984code.



23B.6 ExamplesThese example problems are included for the verification of design results.

23B.6.1 .Example 1 - Pipe Section

This example is included as C:\SProV8i\STAAD\Examp\nuclear code samples\N690_1984_Pipe_Section.std

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 Pipe section made fromGrade 36 steel.

Solution

Section Properties:

Ax = 4.30 in.2

869— STAAD.Pro


Iy = Iz = 15.20 in.4

r = (15.20/4.30)1/2 = 1.88 in.

O.D. = 5.56 in., t = 0.26 in.

Sx = Sy = 15.20 in.4·2/5.56 in. = 5.468 in.3

Load Case 1: Tension-only

Allowable Tensile Stress:

Ft = min(0.6·Fy, 0.5·Fu) = 0.6(36 ksi) = 21.60 ksi

Actual Tensile Stress:

ft = P/Ae

Where:

Ae = Ct·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


Maximum Slenderness Ratio, (Kl/r)max = 1.0(10 ft)(12 ft/in.)/1.88in. = 63.83 < 200,OK.


Cc = [(2π2E)/Fy]1/2 = 127.68

(Kl/r)max < Cc

=−

+ −F Fc y

1.0Kl r

Cc

Kl r

Cc

Kl r

Cc

( / )2

22

5

3

3( / )

8

( / )3

83

= =−

+ −ksi ksi36 17.06

1.0(63.83)

2

2(127.68)2

5

3

3(63.83)

8(127.68)

(63.83)3

8(127.68)3

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 = Fbz = 0.66·Fy = 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·Fy) + fby/Fby + fbz/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 + fby/Fby + fbz/Fbz = 0.136 + 0.363 + 0.346 = 0.845 < 1.0, OK

Comparison

Condition Reference STAAD.Pro Difference

Tension0.144

(0.107, CT = 1.0)0.108

Compression 0.136 0.136 None

Tension + Bending0.853

(0.817, CT = 1.0)0.815 2.51%

Compression + Bending 0.845 0.844 Negligible

Table 23B.2-ANSI/AISC N690-1984 Code Verification Problem 1

Input File

STAAD SPACE


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

871 — STAAD.Pro


1 1 2;


ISOTROPIC STEEL

E 4.176E+006

POISSON 0.3

DENSITY 0.489024

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL

UNIT INCHES KIP


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 UNI GY -0.3

JOINT LOAD

2 FX 10

MEMBER LOAD

1 UNI GZ 0.3

LOAD 4 COMPRESSION+BENDING

SELFWEIGHT Y -1

MEMBER LOAD

1 UNI GY -0.3

JOINT LOAD

2 FX -10

MEMBER LOAD

1 UNI GZ 0.3


PERFORM ANALYSIS PRINT LOAD DATA

PRINT MEMBER PROPERTIES ALL

UNIT INCHES KIP

LOAD LIST 1

PARAMETER 1

CODE AISC N690 1984

CB 1 ALL

CMY 0 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

** FOLLOWING TO CHECK IF THE NET AREA IS USED IN CALCULATINGTENSILE 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

CMY 0 ALL

CMZ 0 ALL

* 36 & 58

FYLD 36 ALL

FU 58 ALL

KY 1 ALL

KZ 1 ALL

MAIN 200 ALL

873— STAAD.Pro


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

CMY 0 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

CMY 0 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 ALL

PARAMETER 5

CODE AISC N690 1984

CB 1 ALL

CMY 0 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:

STAAD.PRO CODE CHECKING - ( AISC N690 1984) v1.0********************************************

ALL UNITS ARE - KIP INCH (UNLESS OTHERWISE NOTED)


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

1 ST PIPS50 (AISC SECTIONS)PASS Q1.6-Eqn 2 0.844 4

10.00 C 44.84 47.02 120.00

875— STAAD.Pro


|-----------------------------------------------------------------------------|| 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 MZ MY|| TENSION 0.108 1 1.00E+01 - - - -|| COMPRESSION 0.136 2 1.00E+01 - - - -|| COMP&BEND 0.844 4 1.00E+01 - - 4.70E+01 4.48E+01|| TEN&BEND 0.815 3 1.00E+01 - - 4.70E+01 4.48E+01|| SHEAR-Y 0.063 3 - 1.96E+00 - - -|| SHEAR-Z 0.060 3 - - 1.87E+00 - -||-----------------------------------------------------------------------------|


23B.6.2 Example 2 - W-Section

This example is included as C:\SProV8i\STAAD\Examp\nuclear code samples\N690_1984_W-Section.std

Problem

A 12 ft long simply supported beam subject to uniform load (3 kip/ft). The beam is a W6x12section 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·Fy = 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:

Fv = 0.4·Fy = 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 23B.3-ANSI/AISC N690-1984 Code Verification Problem 3

877— STAAD.Pro


Input File

STAAD SPACE


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;


ISOTROPIC STEEL

E 4.176E+006

POISSON 0.3

DENSITY 0.489024

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


1 TABLE ST W6X12

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 2 PINNED


SELFWEIGHT Y -1 ALL

MEMBER LOAD

1 UNI GY -0.3

PERFORM ANALYSIS PRINT LOAD DATA

PRINT MEMBER PROPERTIES ALL

*UNIT KIP INCH

PARAMETER 1

CODE AISC N690 1984

CB 1 ALL

CMY 0 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 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********************************************



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

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|

879— STAAD.Pro


| 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 MZ MY|| TENSION 0.000 1 0.00E+00 - - - -|| COMPRESSION 0.000 1 0.00E+00 - - - -|| COMP&BEND 0.387 1 0.00E+00 - - 6.74E+01 0.00E+00|| TEN&BEND 0.000 1 0.00E+00 - - 6.74E+01 0.00E+00|| SHEAR-Y 0.094 1 - 1.87E+00 - - -|| SHEAR-Z 0.000 1 - - 0.00E+00 - -||-----------------------------------------------------------------------------|


881 — STAAD.Pro

Section 24

American Society of Mechanical Engineers – NuclearFacility (ASME NF) Codes


883— STAAD.Pro

24A. ASME NF 3000 - 1974 & 1977 CodesSTAAD.Pro is capable of performing steel design based on the American Society of MechanicalEngineers Nuclear Facility Code, ASME NF 3000 - 1974 & 1977 .

Note: From design point of view, there are no major differences between NF-3000 1974and NF-3000 1977 version of codes.

Design of members per ASME NF 3000 - 1974 & 1977 requires the STAAD Nuclear DesignCodes SELECT Code Pack.

24A.1 Design ProcessThe design process follows the following design checks

Each one of the checks are described in the following sections.

When a design is performed, the output file the reports the maximum utilization from all ofthe checks.

24A.1.1 Slenderness

As per clause XVII-2223 of NF-3000 1974, the slenderness ratio KL/r of compression membersshall not exceed 200, and the slenderness ratio L/r of tension members, preferably should notexceed 240 for main members and 300 for lateral bracing members and other secondarymembers. The default limit for TRUSS members in Tension is set at 300.

24A.1.2 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 of NF-30001974, and the NSF parameter can be utilized for that.


24A.1.3 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) < Cc,

=

−

+ −F Fa y

1

5 / 3

KL r

Cc

KL r

Cc

KL r

Cc

( / )2

22

3( / )

8

( / )3

83

Where:


=Ccπ E

F

2

y

2


=Faπ E

KL r

12

23( / )

2

2

3. When (Kl/r) > 120,

=

−Fas

F Eq a orEq a

( )( ) ( ). 1 . 2

1.6

al

r200

b. Member elements other than columns:

1. For Plate Girder Stiffeners, Fa = 0.60·Fy2. For webs of rolled shapes, Fa = 0.75·Fy

The above clauses are applicable only when the width-thickness ratio of the element satisfiesall 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. Detailedvalues of Qs for 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.


=

−

≤b b1e

t

f b t f( )253 50.3

/


=

−

≤b b1e

t

f b t f( )253 44.3

/

Consequently, a reduction factor, Qa, equal to the effective area divided by the actualarea is introduced.

Combining both these factors, allowable stress for axially loaded compression memberscontaining stiffened or un-stiffened elements shall not exceed

=

−

+ −

′

′ ′

F Fa y

Q Q 1

5 / 3

s a

KL r

C c

KL r

C c

KL r

C c

( / )2

22

3( / )

8

( / )3

83

Where:

′ =C cπ E

Q Q F

2

s a y

2

885— STAAD.Pro

24A. ASME NF 3000 - 1974 & 1977 Codes

24A.1.4 Bending Stress

Allowable bending stress for tension and compression for a structural member, as given inXVII-2214 of NF-3000 1974 is:

a. Along Major Axis:

a. For Compact Sections, tension and compression on extreme fibers of compact hot rolledor built-up members symmetrical about and loaded in the plane of their minor axesand meeting the requirements of Subsection NF shall result in a maximum bendingstress:

Fb = 0.66*FyIf meeting the requirements of this member of:

a. Width-thickness ratio of un-stiffened projecting elements of the compression flangeshall not exceed 52.2/√Fy.

b. Width-thickness ratio of stiffened elements of the compression flange shall not exceed190/√Fy.


d/t = (412/√Fy)[1 – 2.33(Fa/Fy)]

except that it need not be less than 257/√Fy.

d. The laterally unsupported length of the compression flange of members other than box-shaped members shall not exceed the value of 76bf/√Fy nor 20000/(d/Af)Fy.

b. For noncompact and slender elements, clause XVII-2214.2 and XVII-2214.5 of NF-30001974 are followed respectively.

c. For box-type flexural members, maximum bending stress is:

Fb = 0.60*Fyb. 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 bending stress shall not exceed:

Fb = 0.75*Fy

24A.1.5 Combined Interaction Check

Members subjected to both axial compression and bending stresses are proportioned to satisfy

+ + ≤− ′ − ′

1.0f

F

C f

f F F

C f

f F F( )( )1 / 1 /

a

a

mz bz

a ex bx

my by

a ey by

and

+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by


when fa/Fa > 0.15,

otherwise

+ + ≤ 1.0f

F

f

F

f

F

a

a

bz

bz

by

by

It should be noted that during code checking or member selection, if fa/Fa exceeds unity, theprogram does not compute the second and third part of the formula, because this wouldresult in a misleadingly liberal ratio. The value of the coefficient Cm is taken as 0.85 for side-sway and 0.6 - 0.4·(M1/M2), but not less than 0.4 for no side-sway.

Members subjected to both axial tension and bending stress are proportioned to satisfy

+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by

24A.1.6 Shear Stress

Allowable shear stress on the gross section [ref. XVII-2263.2 of NF-3000 1974] is calculated as

= ≤F F C F( )/ 2.89 0.4v y v y

Where:

=Cvk

F h t

45, 000

( / )y2

, when Cv < 0.8

=Cv h t

k

F

190

/ y , when Cv > 0.8

= +k a h4.00 5.34 / ( / )2, when a/h < 1.0

= +k a h5.34 4.00 / ( / )2, when a/h > 1.0


24A.2 Member Property SpecificationFor specification of member properties, the specified steel section available in Steel SectionLibrary of STAAD may be used namely – I-shaped section, Channel, Tee, HSS Tube, HSS Pipe,Angle, Double Angle, Double Channel section.



24A.3 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in the

887— STAAD.Pro

24A. ASME NF 3000 - 1974 & 1977 Codes

following table.

The default parameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements for an analysis,some or all of these parameter values may have to be changed to exactly model the physicalstructure. For example, by default the KZ value (k value in local z-axis) of a member is set to1.0, while in the real structure it may be 1.5. In that case, the KZ value in the program can bechanged to 1.5, as shown in the input instruction (Section 5). Similarly, the TRACK value of amember is set to 0.0, which means no allowable stresses of the member will be printed. If theallowable stresses are to be printed, the TRACK value must be set to 1.0.

Note: Unlike many other design codes available in STAAD.Pro (which use the BEAMparameter), design per ASME NF 3000 codes in STAAD.Pro is always performedbased on forces calculated at 13 sections, including ends.

ParameterName


CODE - Must be specified as CODE NF30001974 or CODE NF3000 1977



0 = Deflection check based on theprinciple that maximum deflectionoccurs within the span between DJ1and DJ2.

1 = Deflection check based on theprinciple that maximum deflection isof the cantilever type

CB 1.0 Bending coefficient dependent uponmoment gradient


Any other user-defined value isaccepted.

CMY

CMZ

0.85 forsidesway andcalculated forno sidesway


Table 24A.1-ASME NF 3000 Design Parameters


ParameterName


DFF None(Mandatoryfor deflection

check)






DMAX 45 inch Maximum allowable depth. Used onlywith the MEMBER SELECTIONcommand.

DMIN 0.0 inch Minimum allowable depth. Used onlywith the MEMBER SELECTIONcommand.

FYLD 36 KSI Yield strength of steel at temperaturein current units.

FU 60 KSI Ultimate tensile strength of steel incurrent units.

KBK 1.0 Stress Limit Factor applicable to theDesign Allowable Compressive Axialand Bending stresses to determine theBuckling Limit.

Note: Ignored unless SRL is set toD.

KS 1.0 Stress Limit Factor applicable to theDesign Allowable Tensile and BendingStresses.


889— STAAD.Pro

24A. ASME NF 3000 - 1974 & 1977 Codes

ParameterName


KV 1.0 Stress Limit Factor applicable to theDesign Allowable Shear Stresses.




LY MemberLength

Length to calculate slenderness ratiofor buckling about local Y axis.

LZ MemberLength




NSF 1.0 Net Section Factor for tensionmember.

PROFILE None Used in member selection. See Section5.48.1 of the Technical ReferenceManual for details.



ParameterName


SRL A Service level, which defines the servicelevel factors to use for modifying stressvalues for the service level conditions.

A. Normal Conditions

B. Upset

C. Emergency

D. Faulted - If any of KS, KV, or KBKparameters are not set, awarning is issued that thesemust be user-defined.

See "Service Level Conditions arebasically the loading conditions forwhich the plant structure and itscomponents are to be designed. Thesame primary load can be multipliedby different factors to signify thedifferent service levels. Also the loadcombinations for various service levelsare different and pre-defined by thecode." on page 934 for additionalinformation.


whichever isgreater

Spacing of stiffeners for plate girderdesign

TMAIN 240 for mainmember

300 for “Truss”member



0. Minimum detail


2. Maximum detail

891 — STAAD.Pro

24A. ASME NF 3000 - 1974 & 1977 Codes

ParameterName


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* flangefor calculating allowable bendingcompressive stress. Will be used only ifflexural compression on the top flange.

24A.4 Code Checking and Member SelectionBoth code checking and member selection options are available with the ASME NF-3000 1974and ASME NF-3000 1977 codes.



24A.5 Example A cantilever beam of length 30 inch is loaded at its free end with 5 kip compressive load and 5kip lateral load. The beam is assigned with W24X104 steel member and is designed inaccordance with ASME NF3000 1974.

The corresponding input of STAAD input editor file is shown as below:

STAAD SPACE


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;


ISOTROPIC STEEL

E 29000


POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


1 TABLE ST W24X104

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

JOINT LOAD

2 FX -5 FY -5

PERFORM ANALYSIS


PRINT JOINT DISPLACEMENTS

PRINT MEMBER FORCES

PARAMETER 1

CODE NF3000 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********************************************



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

1 ST W24X104 (AISC SECTIONS)PASS NF-74-EQN-21 0.032 1

5.00 C 0.00 150.00 0.00|-----------------------------------------------------------------------------|

893— STAAD.Pro

24A. ASME NF 3000 - 1974 & 1977 Codes

| SLENDERNESS CHECK: ACTUAL RATIO: 9.28 ALLOWABLE RATIO: 200.00|| 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 - -||-----------------------------------------------------------------------------|


895— STAAD.Pro

24B. ASME NF 3000 - 1989 Code

24B.1 Design ProcessThe design process follows the following design checks.

1. Slenderness

2. Tension

3. Compression

4. Bending Stress


6. Shear Stress



24B.2 .1 SlendernessAs per NF-3322.2(c), the slenderness ratio KL/r of compression members shall not exceed 200,and the slenderness ratio L/r of tension members, preferably should not exceed 240 for mainmembers and 300 for lateral bracing members and other secondary members. The default limitfor TRUSS members in Tension is set at 300.

24B.3 .2 Tension Allowable tensile stress on the Net section is calculated as (0.60*F

y), 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 the member, shall becomputed from the formula (ref. NF-3322.8(c)(1)(d)),

Ae= C

t* A

nUnless 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).



24B.4 .3 Compression The allowable compressive stress for columns, except those fabricated from austenitic stainlesssteel shall be as required by NF-3322.1(c)(1). The allowable compressive stress for columnsfabricated from austenitic stainless steel shall be as required by NF-3322.1(c)(2). The allowablecompressive stress for member elements other than columns constructed by any material,including austenitic stainless steel, shall be as required by NF-3322.1(c)(3).

a. Gross Sections of Columns, except those fabricated of austenitic stainless steel:


=

−

+ −F Fa y

1

5 / 3

KL r

Cc

KL r

Cc

KL r

Cc

( / )2

22

3( / )

8

( / )3

83

Where:

=Ccπ E

F

2

y

2


=Faπ E

KL r

12

23( / )

2

2

3. When (Kl/r) > 120,

=

−Fas

F Eq a orEq a

( )( ) ( ). 1 . 2

1.6

al

r200

b. Gross sections of columns fabricated from Austenitic Stainless steel:

1. When (Kl/r) ≤ 120,

= −F F ( )0.47a y

KL r/

444

2. When (Kl/r) > 120,

= −F F ( )0.40a y

KL r/

600

c. Member elements other than columns:


The above clauses are applicable only when the width-thickness ratio of the element satisfiesall the sub-sections of NF-3322.2(d).


897— STAAD.Pro

a. For un-stiffened compression element, a reduction factor, Qs, is introduced. Detailedvalues of Qs for different shapes are given in NF-3322.2(e)(2)(a) to NF-3322.2(e)(2)(d).



=

−

≤b b1e

t

f b t f( )253 50.3

/


=

−

≤b b1e

t

f b t f( )253 44.3

/



=

−

+ −

′

′ ′

F Fa y

Q Q 1

5 / 3

s a

KL r

C c

KL r

C c

KL r

C c

( / )2

22

3( / )

8

( / )3

83

Where:

′ =C cπ E

Q Q F

2

s a y

2

24B.5 .4 Bending Stress Allowable bending stress for tension and compression for a structural member, as given in NF-3322.1(d) is:


1. For Compact Sections, tension and compression on extreme fibres of compact hot rolledor built-up members symmetrical about and loaded in the plane of their minor axesand meeting the requirements of Subsection NF shall result in a maximum bendingstress:

Fb= 0.66*F

yIf meeting the requirements of this member of:

a. Width-thickness ratio of unstiffened projecting elements of the compression flangeshall not exceed 65/√F

y.

b. Width-thickness ratio of stiffened elements of the compression flange shall not exceed190/√F

y.


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 other thanbox-shaped members shall not exceed the value 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) arefollowed respectively.


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 stress shall 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/√F

y, maximum tensile and

compressive bending stress shall not exceed:

Fb= F

y[1.075 – 0.005(b

f/2tf)√F

y]

24B.6 .5 Combined Interaction Check Members subjected to both axial compression and bending stresses are proportioned to satisfy

+ + ≤− ′ − ′

1.0f

F

C f

f F F

C f

f F F( )( )1 / 1 /

a

a

mz bz

a ex bx

my by

a ey by

and

+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by

when fa/Fa > 0.15,

otherwise

+ + ≤ 1.0f

F

f

F

f

F

a

a

bz

bz

by

by



+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by

24B.7 .6 Shear Stress Allowable shear stress on the gross section [ref. NF-3322.6(e)(2)] is calculated as

899— STAAD.Pro

= ≤F F C F( )/ 2.89 0.4v y v y

Where:

=Cvk

F h t

45, 000

( / )y2

, when Cv < 0.8

=Cv h t

k

F

190

/ y , when Cv > 0.8

= +k a h4.00 5.34 / ( / )2, when a/h < 1.0

= +k a h5.34 4.00 / ( / )2, when a/h > 1.0


24B.8 Member Property SpecificationFor specification of member properties, the specified steel section available in Steel SectionLibrary of STAAD may be used namely – I-shaped section, Channel, Tee, HSS Tube, HSS Pipe,Angle, Double Angle, Double Channel section.



24B.9 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in thefollowing table.




ParameterName


CODE - Must be specified as NF3000 1989.




0 = Deflection check based on theprinciple that maximum deflectionoccurs within the span between DJ1and DJ2.

1 = Deflection check based on theprinciple that maximum deflection isof the cantilever type

CB 1.0 Bending coefficient dependent uponmoment gradient


Any other user-defined value isaccepted.

CT 0.75 Reduction Coefficient in computingeffective net area of an axially loadedtension member. [Refer NF-3322.8(c)(1)(d)]

CMY

CMZ

0.85 for sideswayand calculated forno sidesway








DMAX 45 inch Maximum allowable depth, incurrent units. Used only with theMEMBER SELECTION command.

Table 24B.1-ASME NF 3000 Design Parameters

901 — STAAD.Pro

ParameterName


DMIN 0.0 inch Minimum allowable depth, incurrent units. Used only with theMEMBER SELECTION command.

FYLD 36 KSI Yield strength of steel at temperaturein current units.

FU 60 KSI Ultimate tensile strength of steel incurrent units.

KBK 1.0 Stress Limit Factor applicable to theDesign Allowable Compressive Axialand Bending stresses to determinethe Buckling Limit.

Note: Ignored unless SRL is setto D.

KS 1.0 Stress Limit Factor applicable to theDesign Allowable Tensile andBending Stresses.


KV 1.0 Stress Limit Factor applicable to theDesign Allowable Shear Stresses.




LY Member Length Length to calculate slenderness ratiofor buckling about local Y axis.

LZ Member Length Same as above except in z-axis(major).


ParameterName





PROFILE None Used in member selection. SeeSection 5.48.1 of the TechnicalReference Manual for details.


SRL A Service level, which defines theservice level factors to use formodifying stress values for the servicelevel conditions.


B. Upset

C. Emergency

D. Faulted - If any of KS, KV, orKBK parameters are not set, awarning is issued that thesemust be user-defined.

See "Service Level Conditions arebasically the loading conditions forwhich the plant structure and itscomponents are to be designed. Thesame primary load can be multipliedby different factors to signify thedifferent service levels. Also the loadcombinations for various servicelevels are different and pre-definedby the code." on page 934 foradditional information.

STIFF Member length ordepth whichever isgreater

Spacing of stiffeners for plate girderdesign



903— STAAD.Pro

ParameterName


TMAIN 240 for mainmember




0 = Minimum detail


2 = Maximum detail

UNB Member Length Unsupported length of the bottom*flange for calculating allowablebending compressive stress. Will beused only if flexural compression onthe bottom flange.

UNT Member Length Unsupported length of the top*flange for calculating allowablebending compressive stress. Will beused only if flexural compression onthe top flange.

24B.10 Code Checking and Member SelectionBoth code checking and member selection options are available with the ASME NF-3000 1989code.



24B. 18B.6 Example A cantilever beam of length 100 inch is loaded at its free end with 5 kip compressive load and auniformly distributed load of 1 kip/inch over the whole span. The beam is assigned withB571806 steel member and is designed in accordance with ASME NF3000 1989.


STAAD SPACE




END JOB INFORMATION

JOINT COORDINATES

1 0 0 0; 2 360 0 0;

MEMBER INCIDENCES

1 1 2;


ISOTROPIC STEEL

E 29000

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


1 TABLE ST B571806

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

JOINT LOAD

2 FX -5

MEMBER LOAD

1 UNI GY -1.0 0 100

PERFORM ANALYSIS


PARAMETER 1

CODE NF3000 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

905— STAAD.Pro

24B. 18B.6 Example





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

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)|| 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 - -||-----------------------------------------------------------------------------|

907— STAAD.Pro

24B. 18B.6 Example

24C. ASME NF 3000 - 2004 Code

24C.1 Design ProcessThe design process follows the following design checks.

1. Slenderness

2. Tension

3. Compression

4. Bending Stress


6. Shear Stress



24C.2 .1 Slenderness As per NF-3322.2(c), the slenderness ratio KL/r of compression members shall not exceed 200,and the slenderness ratio L/r of tension members, preferably should not exceed 240 for mainmembers and 300 for lateral bracing members and other secondary members. The default limitfor TRUSS members in Tension is set at 300.

24C.3 .2 Tension Allowable tensile stress on the Net section is calculated as (0.60*F

y), 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 the member, shall becomputed from the formula (ref. NF-3322.8(c)(1)(d)),

Ae= C

t* A

nUnless 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).



24C.4 .3 Compression The allowable compressive stress for columns, except those fabricated from austenitic stainlesssteel shall be as required by NF-3322.1(c)(1). The allowable compressive stress for columnsfabricated from austenitic stainless steel shall be as required by NF-3322.1(c)(2). The allowablecompressive stress for member elements other than columns constructed by any material,including austenitic stainless steel, shall be as required by NF-3322.1(c)(3).

a. Gross Sections of Columns, except those fabricated of austenitic stainless steel:


=

−

+ −F Fa y

1

5 / 3

KL r

Cc

KL r

Cc

KL r

Cc

( / )2

22

3( / )

8

( / )3

83

Where:

=Ccπ E

F

2

y

2


=Faπ E

KL r

12

23( / )

2

2

3. When (Kl/r) > 120,

=

−Fas

F Eq a orEq a

( )( ) ( ). 1 . 2

1.6

al

r200

b. Gross sections of columns fabricated from Austenitic Stainless steel:

1. When (Kl/r) ≤ 120,

= −F F ( )0.47a y

KL r/

444

2. When (Kl/r) > 120,

= −F F ( )0.40a y

KL r/

600

c. Member elements other than columns:


The above clauses are applicable only when the width-thickness ratio of the element satisfiesall the sub-sections of NF-3322.2(d).


909— STAAD.Pro

24C. ASME NF 3000 - 2004 Code

a. For un-stiffened compression element, a reduction factor, Qs, is introduced. Detailedvalues of Qs for 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 for projectingelements of compression flanges of girder,

When < <F kc b t F kc95 / / / 195 / /y y , = −Q b t F kc( )1.293 0.00309 / /s y

When >b t F kc/ 195 / /y ,

=Qs

kc

F b t

26, 200

( / )y2

Where:

=kch t

4.05

( / )0.46 when h/t > 70, otherwise, kc = 1.0.



=

−

≤b b1e

t

f b t f( )253 50.3

/


=

−

≤b b1e

t

f b t f( )253 44.3

/



=

−

+ −

′

′ ′

F Fa y

Q Q 1

5 / 3

s a

KL r

C c

KL r

C c

KL r

C c

( / )2

22

3( / )

8

( / )3

83

Where:

′ =C cπ E

Q Q F

2

s a y

2

24C.5 .4 Bending Stress Allowable bending stress for tension and compression for a structural member, as given in NF-3322.1(d) is:



1. For Compact Sections, tension and compression on extreme fibres of compact hotrolled or built-up members symmetrical about and loaded in the plane of their minoraxes and meeting the requirements of Subsection NF shall result in a maximumbending stress:

Fb= 0.66*F

yIf meeting the requirements of this member of:

a. Width-thickness ratio of unstiffened projecting elements of the compression flangeshall not exceed 65/√F

y.

b. Width-thickness ratio of stiffened elements of the compression flange shall not exceed190/√F

y.


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 other thanbox-shaped members shall not exceed the value of 76b

f/√F

ynor 20000/(d/A

f)Fy.



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 stress shall 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/√F

y, maximum tensile and

compressive bending stress shall not exceed:

Fb= F

y[1.075 – 0.005(b

f/2tf)√F

y]

24C.6 .5 Combined Interaction CheckMembers subjected to both axial compression and bending stresses are proportioned to satisfy

+ + ≤− ′ − ′

1.0f

F

C f

f F F

C f

f F F( )( )1 / 1 /

a

a

mz bz

a ex bx

my by

a ey by

and

+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by

when fa/Fa > 0.15,

911 — STAAD.Pro

24C. ASME NF 3000 - 2004 Code

otherwise

+ + ≤ 1.0f

F

f

F

f

F

a

a

bz

bz

by

by



+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by

24C.7 .6 Shear Stress Allowable shear stress on the gross section [ref. NF-3322.6(e)(2)] is calculated as

= ≤F F C F( )/ 2.89 0.4v y v y

Where:

=Cvk

F h t

45, 000

( / )y2

, when Cv < 0.8

=Cv h t

k

F

190

/ y , when Cv > 0.8

= +k a h4.00 5.34 / ( / )2, when a/h < 1.0

= +k a h5.34 4.00 / ( / )2, when a/h > 1.0


24C.8 Member Property SpecificationFor specification of member properties, the specified steel section available in Steel SectionLibrary of STAAD may be used namely – I-shaped section, Channel, Tee, HSS Tube, HSS Pipe,Angle, Double Angle, Double Channel section.



24C.9 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in thefollowing table.




ParameterName


CODE - Must be specified as NF30001998.



CAN 0 Used for Deflection Checkonly.

0 = Deflection check based onthe principle that maximumdeflection occurs within thespan between DJ1 and DJ2.

1 = Deflection check based onthe principle that maximumdeflection is of the cantilevertype

CB 1.0 Bending coefficientdependent upon momentgradient


Any other user-defined valueis accepted.

Table 24C.1-ASME NF 3000 1998 Design Parameters

913— STAAD.Pro

24C. ASME NF 3000 - 2004 Code

ParameterName


CMY

CMZ

0.85 for sidesway andcalculated for no

sidesway


CT 0.75 Reduction Coefficient incomputing effective net areaof an axially loaded tensionmember. [Refer NF-3322.8(c)(1)(d)]


"Deflection Length" /Maximum allowable localdeflection


Joint No. denoting startingpoint for calculation of"Deflection Length"

DJ2 End Joint of member Joint No. denoting end pointfor calculation of "DeflectionLength"

DMAX 45 inch Maximum allowable depth, incurrent units. Used only withthe MEMBER SELECTIONcommand.

DMIN 0.0 inch Minimum allowable depth, incurrent units. Used only withthe MEMBER SELECTIONcommand.

FYLD 36 KSI Yield strength of steel attemperature in current units.

FU 60 KSI Ultimate tensile strength ofsteel in current units.


ParameterName


KBK 1.0 Stress Limit Factor applicableto the Design AllowableCompressive Axial andBending stresses to determinethe Buckling Limit.

Note: Ignored unless SRLis set to D.

KS 1.0 Stress Limit Factor applicableto the Design AllowableTensile and Bending Stresses.


KV 1.0 Stress Limit Factor applicableto the Design AllowableShear Stresses.


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 for bucklingabout local Y axis.

LZ Member Length Same as above except in z-axis(major).


1.0 = suppress slendernesscheck


915— STAAD.Pro

24C. ASME NF 3000 - 2004 Code

ParameterName


PROFILE None Used in member selection.See Section 5.48.1 of theTechnical Reference Manualfor details.

RATIO 1.0 Permissible ratio of the actualto allowable stresses.

SRL A Service level, which definesthe service level factors to usefor modifying stress values forthe service level conditions.


B. Upset

C. Emergency

D. Faulted - If any of KS,KV, or KBK parametersare not set, a warningis issued that thesemust be user-defined.

See "Service Level Conditionsare basically the loadingconditions for which theplant structure and itscomponents are to bedesigned. The same primaryload can be multiplied bydifferent factors to signify thedifferent service levels. Alsothe load combinations forvarious service levels aredifferent and pre-defined bythe code." on page 934 foradditional information.

STIFF Member length ordepth whichever is

greater

Spacing of stiffeners for plategirder design




ParameterName


TMAIN 240 for main member


Slenderness limit undertension

TRACK 0.0 Controls the levels of detailto which results are reported.

0 = Minimum detail


2 = Maximum detail

UNB Member Length Unsupported length of thebottom* flange forcalculating allowable bendingcompressive stress. Will beused only if flexuralcompression on the bottomflange.

UNT Member Length Unsupported length of thetop* flange for calculatingallowable 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.

24C.10 Code Checking and Member SelectionBoth code checking and member selection options are available with the ASME NF-3000 1998code.



917— STAAD.Pro

24C. ASME NF 3000 - 2004 Code

24C. 18C.6 Example A cantilever beam of length 100 inch is loaded at its free end with 5 kip compressive load and auniformly distributed load of 1 kip/inch over the whole span. The beam is assigned withB571806 steel member and is designed in accordance with ASME NF3000 1998.


STAAD SPACE



END JOB INFORMATION

UNIT INCHES KIP

JOINT COORDINATES

1 0 0 0; 2 100 0 0;

MEMBER INCIDENCES

1 1 2;


ISOTROPIC STEEL

E 29000

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


1 TABLE ST B571806

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

JOINT LOAD

2 FX -5

MEMBER LOAD

1 UNI GY -1.0 0 100

PERFORM ANALYSIS

PARAMETER 1

CODE NF3000 1998

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





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

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|

919— STAAD.Pro

24C. 18C.6 Example

| 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 - -||-----------------------------------------------------------------------------|


921 — STAAD.Pro

24D. ASME NF 3000 - 2001 & 2004 CodesSTAAD.Pro is capable of performing steel design based on the American Society of MechanicalEngineers Nuclear Facility Code, ASME NF 3000 - 2004.

Note: Use of 2004 edition requires STAAD.Pro V8i (SELECTseries 2) NRC (build20.07.07.30) or higher. Use of 2001 edition requires STAAD.Pro V8i (SELECTseries 3)NRC (build 20.07.08.22) or higher.

Design of members per ASME NF 3000 - 2001 & 2004 requires the STAAD Nuclear DesignCodes SELECT Code Pack.

24D.1 Design ProcessThe design process follows the following design checks.

1. Slenderness

2. Tension

3. Compression

4. Bending Stress


6. Shear Stress

Each one of the checks is described in the following sections.


24D.1.1 Slenderness

As per NF-3322.2(c), the slenderness ratio KL/r of compression members shall not exceed 200,and the slenderness ratio L/r of tension members, preferably should not exceed 240 for mainmembers and 300 for lateral bracing members and other secondary members. The default limitfor TRUSS members in Tension is set at 300.

24D.1.2 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 transmittedby bolts through some but not all of the cross-sectional elements of the member, shall becomputed from the formula (ref. NF-3322.8(c)(1)(d)),

Ae = Ct · 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).


24D.1.3 Compression

The allowable compressive stress for columns, except those fabricated from austenitic stainlesssteel shall be as required by NF-3322.1(c)(1). The allowable compressive stress for columnsfabricated from austenitic stainless steel shall be as required by NF-3322.1(c)(2). The allowablecompressive stress for member elements other than columns constructed by any material,including austenitic stainless steel, shall be as required by NF-3322.1(c)(3).

A. Gross Sections of Columns, except those fabricated of austenitic stainless steel:

1. On gross section of axially loaded compression members, when (Kl/r) ≤ Cc,

Fa = [1 - (Kl/r)2/(2·Cc2)]Fy / 5/3 + [3(Kl/r)/(8·Cc)] - [(Kl/r)

3/(8·Cc3)]

(Eq. A1)

Where:

Cc = [(2·π2E)/Fy]1/2


Fa = 12·π2E/[23(kL/r)2]

(Eq. A2)

3. When (Kl/r) > 120,

Fas = Fa[(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 = Fy[0.47 - (Kl/r)/444]

2. When (Kl/r) > 120,

Fa = Fy[0.40 - (Kl/r)/600]

C. Member elements other than columns:

1. For Plate Girder Stiffeners,

Fa = 0.60·Fy2. For webs of rolled shapes,

Fa = 0.75·Fy

923— STAAD.Pro

24D. ASME NF 3000 - 2001 & 2004 Codes

The above clauses are applicable only when the width-thickness ratio of the elementsatisfies all the sub-sections of NF-3322.2(d)..


a. For un-stiffened compression element,

A reduction factor Qs is introduced. Detailed values of Qs for different shapes are givenin 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 for projectingelements of compression flanges of girder,

When 95/(Fy/kc)1/2 < b/t < 195/(Fy/kc)

1/2, Qs = 1.293 - 0.00309·(b/t)·(Fy/kc)1/2

When b/t > 195/(Fy/kc)1/2, Qs = 26,200·kc/[Fy(b/t)

2)]

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 be is introduced.


be = 253·t/√(f)1 - 50.3/[(b/t)√(f)] ≤ b


be = 253·t/√(f)1 - 44.3/[(b/t)√(f)] ≤ b

Consequently, a reduction factor Qa is introduced and is equal to the effective areadivided by the actual area. Combining both these factors, allowable stress for axiallyloaded compression members containing stiffened or unstiffened elements shall notexceed

Fa = QsQa[1 - (Kl/r)2/(2·Cc

2)]Fy / 5/3 + [3(Kl/r)/(8·Cc)] - [(Kl/r)3/(8·Cc

3)]

Where:

C'c = [(2·π2E)/(QsQaFy)]1/2

24D.1.4 Bending Stress

Allowable bending stress for tension and compression for a structural member, as given in NF-3322.1(d) is:

A. Along Major Axis:

1. For Compact Sections, tension and compression on extreme fibres of compacthot rolled or built-up members symmetrical about and loaded in the plane oftheir minor axes and meeting the requirements of Subsection NF shall result in amaximum bending stress:

Fb = 0.66·Fy


If meeting the requirements of this member of:

a. Width-thickness ratio of unstiffened projecting elements of thecompression flange shall not exceed 65/√Fy.

b. Width-thickness ratio of stiffened elements of the compression flangeshall not exceed 190/√Fy.


d/t = (640/√Fy)[1 – 3.74(fa/Fy)] when fa/Fy ≤ 0.16

d/t = 257/√Fy when fa/Fy > 0.16

d. The laterally unsupported length of the compression flange of membersother than box-shaped members shall not exceed the value of 76bf/√Fynor 20000/(d/Af)Fy.



Fb = 0.75·FyB. 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 stress shallnot exceed:

Fb = 0.75·Fy2. For doubly symmetrical members (I shaped) meeting the requirements of NF-

3322.1(d)(1)(a), except where bf/2tf > 65/√Fy but is less than 95/√Fy, maximumtensile and compressive bending stress shall not exceed:

Fb = Fy[1.075 – 0.005(bf/2tf)√Fy]

24D.1.5 Combined Interaction Check

Members subjected to both axial compression and bending stresses are proportioned to satisfy

+ + ≤− ′ − ′

1.0f

F

C f

f F F

C f

f F F( )( )1 / 1 /

a

a

mz bz

a ex bx

my by

a ey by

and

+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by

when fa/Fa > 0.15,

otherwise

+ + ≤ 1.0f

F

f

F

f

F

a

a

bz

bz

by

by

925— STAAD.Pro

24D. ASME NF 3000 - 2001 & 2004 Codes



+ + ≤ 1.0f

F

f

F

f

F0.60

a

y

bz

bz

by

by

24D.1.6 Shear Stress

Allowable shear stress on the gross section [ref. NF-3322.6(e)(2)] is calculated as

= ≤F F C F( )/ 2.89 0.4v y v y

Where:

=Cvk

F h t

45, 000

( / )y2

, when Cv < 0.8

=Cv h t

k

F

190

/ y , when Cv > 0.8

= +k a h4.00 5.34 / ( / )2, when a/h < 1.0

= +k a h5.34 4.00 / ( / )2, when a/h > 1.0


24D.2 Member Property SpecificationFor specification of member properties, the specified steel section available in Steel SectionLibrary of STAAD may be used namely – I-shaped section, Channel, Tee, HSS Tube, HSS Pipe,Angle, Double Angle, Double Channel section.



24D.3 Design ParametersThe program contains a large number of parameter names which are required to performdesign and code checks. These parameter names, with their default values, are listed in thefollowing table.

The default parameter values have been selected such that they are frequently used numbersfor conventional design. Depending on the particular design requirements for an analysis,some or all of these parameter values may have to be changed to exactly model the physicalstructure. For example, by default the KZ value (k value in local z-axis) of a member is set to


1.0, while in the real structure it may be 1.5. In that case, the KZ value in the program can bechanged to 1.5, as shown in the input instruction (Section 5). Similarly, the TRACK value of amember is set to 0.0, which means no allowable stresses of the member will be printed. If theallowable stresses are to be printed, the TRACK value must be set to 1.0.


ParameterName

DefaultValue

Description

CODE - Must be specified as NF3000 2001 or NF30002004

Specified design code is followed for codechecking purpose.



CB 1.0 Bending coefficient dependent upon momentgradient



CMY

CMZ

0.85 forsideswayand



CT 0.75 Reduction Coefficient in computing effectivenet area of an axially loaded tension member.[Refer NF-3322.8(c)(1)(d)]

DFF None

(Mandatoryfor

deflectioncheck)


Table 24D.1-ASME NF 3000 2001 & 2004 Design Parameters

927— STAAD.Pro

24D. ASME NF 3000 - 2001 & 2004 Codes

ParameterName

DefaultValue

Description

DJ1 Start Jointof themember


DJ2 End Jointof themember

Joint No. denoting end point for calculationof "Deflection Length"



FYLD 36 KSI Yield strength of steel at temperature incurrent units.

FU 60 KSI Ultimate tensile strength of steel in currentunits.

KBK 1.0 Stress Limit Factor applicable to the DesignAllowable Compressive Axial and Bendingstresses to determine the Buckling Limit.

Note: Ignored unless SRL is set to D.

KS 1.0 Stress Limit Factor applicable to the DesignAllowable Tensile and Bending Stresses.


KV 1.0 Stress Limit Factor applicable to the DesignAllowable Shear Stresses.


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.

LY MemberLength

Length to calculate slenderness ratio forbuckling about local Y axis.

LZ MemberLength



ParameterName

DefaultValue

Description



NSF 1.0 Net Section Factor for tension member.


SRL A Service level, which defines the service levelfactors to use for modifying stress values forthe service level conditions.


B. Upset

C. Emergency

D. Faulted - If any of KS, KV, or KBKparameters are not set, a warning isissued that these must be user-defined.

See "Service Level Conditions are basically theloading conditions for which the plantstructure and its components are to bedesigned. The same primary load can bemultiplied by different factors to signify thedifferent service levels. Also the loadcombinations for various service levels aredifferent and pre-defined by the code." onpage 934 for additional information.


whicheveris greater

Spacing of stiffeners for plate girder design



929— STAAD.Pro

24D. ASME NF 3000 - 2001 & 2004 Codes

ParameterName

DefaultValue

Description

TRACK 0.0 Controls the levels of detail to which resultsare reported.

0. Minimum detail


2. Maximum detail

UNB MemberLength

Unsupported length of the bottom* flangefor calculating allowable bending compressivestress. Will be used only if flexuralcompression on the bottom flange.

UNT MemberLength


Notes

1. All values are entered in the current units.

2. The parameters DMAX and DMIN are only used with the MEMBER SELECTION command.

24D.4 Code Checking and Member SelectionBoth code checking and member selection options are available with the ASME NF-3000 2004code.



24D.5 Example of 2004 CodeA cantilever beam of length 100 inch is loaded at its free end with 5 kip compressive load and auniformly distributed load of 1 kip/inch over the whole span. The beam is assigned withB571806 steel member and is designed in accordance with ASME NF3000 2004.


STAAD SPACE




END JOB INFORMATION

UNIT INCHES KIP

JOINT COORDINATES

1 0 0 0; 2 100 0 0;

MEMBER INCIDENCES

1 1 2;


ISOTROPIC STEEL

E 29000

POISSON 0.3

DENSITY 76.8195

ALPHA 1.2E-005

DAMP 0.03

END DEFINE MATERIAL


1 TABLE ST B571806

CONSTANTS

MATERIAL STEEL ALL

SUPPORTS

1 FIXED

LOAD 1

JOINT LOAD

2 FX -5

MEMBER LOAD

1 UNI GY -1.0 0 100

PERFORM ANALYSIS

PARAMETER 1

CODE NF3000 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


931 — STAAD.Pro

24D. ASME NF 3000 - 2001 & 2004 Codes




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

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||-----------------------------------------------------------------------------|| 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 - -||-----------------------------------------------------------------------------|

933— STAAD.Pro

24D. ASME NF 3000 - 2001 & 2004 Codes

Service Level Conditions are basically the loading conditions for which the plant structure andits components are to be designed. The same primary load can be multiplied by differentfactors to signify the different service levels. Also the load combinations for various servicelevels are different and pre-defined by the code.

24E.1 Service LevelsThe following is a short overview of each of the service levels specified by the code:

Condition Description

A. NormalWorking

B. Upset This situation can be termed as a short term failure or alocal failure, and the repairing or modification of thestructure can be done without shutting the entire plant.

C.Emergency

This situation can be termed as a major failure, and therepairing of the structure can be done only after shuttingdown the entire plant.

D. Faulted This situation can be termed as devastation, and the mainobjective of this level is to have sufficient time for saferelocation of human life and valuable properties, and toinitiate the controlled failure of the plant structure. Theplant is already at an unusable state and a rare chance torepair it back into the operation.

These Service Levels are the attribute of the whole structure or the structural system. So, theexistence of different Service Levels to the different parts of the structure at the same point oftime is totally ruled out.

The Service Level Factors are basically few multiplying factor by which the Allowable Stressvalues are to be multiplied based on the Service Level. The different actions (e.g. Tension,Compression, Bending, Shear etc.) have different Service Level Factors.

However, this is to be noted, the stipulated multiplying factors for creating load combinationsfor Service Level B, C, and D are to be user defined in this case. The facility of creating AutoLoad Combination for different Service Levels is out of the scope of this implementation. Theuser has to take care of this.

24E.2 Stress Level FactorsFor the Member Design, as per Clause NF-3321.1, the Allowable Stresses may be increased by theFactors as per Table NF-3523(b)-1 and NF-3623(b)-1. Table NF-3523(b)-1 is applicable toComponent Support Structures and Table NF-3623(b)-1 is applicable to Piping SupportStructures. However, as the values are the same for the service level factors in each table,STAAD.Pro does not make any differentiation between component and piping supports.


Note: Clause NF-3321.1 also indicates that the allowable stress shall be limited to two-thirds (2/3x) the critical buckling stress. However, the critical buckling stress is notclearly defined so it is left to the user to ensure that this code requirement is met.

The values used for the stress level factors in STAAD.Pro are as follows:

Service Level Ks Kv Kbk

A 1.0 1.0 1.0

B 1.33 1.33 1.33

C 1.50 1.50 1.50

D* KS KV KBK

* It is evident from the Table NF-3523(b)-1, that there are no predefined Stress Limit Factorsfor Service Level D. So, for Service Level D, the Factors Ks, Kv and Kbk are to be user defined.Refer to Appendix F in the code for guidance on values to specify in the design parameters.

where

KsStress Limit Factor applicable to the Design Allowable Tensile and BendingStresses.

KvStress Limit Factor applicable to the Design Allowable Shear Stresses

KbkStress Limit Factor applicable to the Design Allowable Compressive Axial andBending stresses to determine the Buckling Limit.

The program uses the service level factors—either those specified for levels A through C or theuser defined values in level D—as follows:

l The Allowable Axial Tensile Stress is to be multiplied by Ks

l The Allowable Axial Compressive Stress is to be multiplied by Kbk

l The Allowable Bending Stress is to be multiplied by Ks

l The Allowable Shear Stress is to be multiplied by Kv

l As per NF-3322.1.(e), for checking Combined Stresses as per equation 20, the value ofF’ey and F’ez – the Euler Stress divided by the factor of safety, may also be multipliedby the appropriate Stress Limit Factor. This is also implemented. F’e is to be multipliedby Kbk

935— STAAD.Pro

Section 24

Technical SupportThese resources are provided to help you answer support questions:

l Service Ticket Manager — http://www.bentley.com/serviceticketmanager — Createand track a service ticket using Bentley Systems' online site for reporting problems orsuggesting new features. You do not need to be a Bentley SELECT member to useService Ticket Manager, however you do need to register as a user.

l Knowledge Base — http://appsnet.bentley.com/kbase/— Search the Bentley Systemsknowledge 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-technotes-and-faqs.aspx— Here you can find detailed resolutions and answers to the mostcommon questions posted to us by you.

l Ask Your Peers — http://communities.bentley.com/forums/5932/ShowForum.aspx— Post questions in the Be Community forums to receive help and advice from fellowusers.

Section 24 Technical Support


http://www.bentley.com/serviceticketmanager

http://appsnet.bentley.com/kbase/

http://communities.bentley.com/Products/Structural/Structural_Analysis___Design/w/Structural_Analysis_and_Design__Wiki/structural-product-technotes-and-faqs.aspx














http://communities.bentley.com/forums/5932/ShowForum.aspx

937— STAAD.Pro

Index

A

AIJ 1991See Concrete Design, AIJ1991

AIJ 2002See Steel Design, AIJ 2002

AIJ 2005See Steel Design, AIJ 2005

AISC 80

Alclad 804

Aluminum Design 802

American Transmission TowerCode 822

Analysis

PDelta 14

ANSI/AISC N690 Codes 844

AS 1170 21

AS 3600 - 2001See Concrete Design,AS 3600

AS 4100 - 1998See Steel Design, AS4100

ASCE 10-97See Steel Design, ASCE10-97

ASCE Manuals 822

ASME NF Codes 882

Australian Codes 9

Axial Compression 817

Axial Tension 817

Clause 3.13 817

Axially Loaded Members 222, 238,240, 242

Design 222, 238, 240, 242

B

British

Codes 49

National AnnexSee NationalAnnex, British

British Codes 67

BS 5950-5See Steel Design, BS 5950-5

BS EN 1993-1-1 281

BS4360 79

BS5400See Steel Design, BS5400

BS5950See Steel Design, BS5950

BS8110See Concrete Design, BS8110

C

CAN/CSA-086-01See Wood Design,CAN/CSA-086-01

Canadian Codes 119

Canadian Wood DesignManual 183

Cold Formed Steel

IS801 512

Concrete Design

AIJ 1991 550

AS 3600 11

B4 378

BBK 94 796

BS8007 97

BS8110 51, 54

CP65 746

CSA A23.3 121

Cyprus 193


Index: CSA – Japanese

DIN 1045 406

EHE 786

Eurocode EC2 213

IS13920 448

IS456 426

NS 3473 692

NTC 1987 592

SABS-0100-1 754

CSA 122, 125

CSA A23.3See Concrete Design,CSA A23.3

CSA CAN/CSA-S16-01See SteelDesign, CSA CAN/CSA-S16-01

D

DD ENV 219

DD ENV 1993 219, 222

Design 222, 238, 240, 242, 254

Axially Loaded Members 222,238, 240, 242

Design Rules 394

Structural Steelwork 394

Dutch

National AnnexSee NationalAnnex, Dutch

E

EC5 356

EN 1993 235

Equivalent slenderness 73

Eurocode 219, 222, 237-238, 240,242, 254

Steel Design 222, 238, 240, 242,254

European Codes 211, 213, 237-238,240, 242, 254

Extrusions 807

F

Finnish

National AnnexSee NationalAnnex, Finnish

French

Codes 386

Concrete Design 388

National AnnexSee NationalAnnex, French

Steel Design 394

G

GB 1591 79

I

IS 800 2007See Steel Design, IS 8002007

IS13920See Concrete Design,IS13920

IS456See Concrete Design, IS456

IS801See Steel Design, IS801

J

Japanese

Codes 548

Concrete DesignSee ConcreteDesign, AIJ 1991

939— STAAD.Pro

Steel DesignSee Steel Design,AIJ 2005

M

Modulus of Elasticity 26

MS NE 1993-1-1 282

N

N690 Codes 844

National Annex 235, 268

Belgian 282

British 281

Dutch 281

Finnish 282

French 282

Malaysian 282

Norwegian 282

output 278

Polish 282

Singaporean 282

National ApplicationDocuments 213, 220

NBN EN 1993-1-1 282

NEN-EN 1993 281

NF EN 1993-1-1 282

Norwegian

National AnnexSee NationalAnnex, Norwegian

NS-EN 1993 282

NTC 1987See Concrete Design, NTC1987

P

PN EN 1993-1-1 282

Polish

National AnnexSee NationalAnnex, Polish

S

S136-94See Steel Design, S136-94

SAB0162-1 1993See Steel Design,SAB0162-1 1993

SABS-0100-1See Concrete Design,SABS-0100-1

SFS EN 1993-1-1 282

SNiP 2.23-81See Steel Design, SNiP2.23-81

SS EN 1993-1-1 282

Star Angle 530

Steel Design 222, 238, 240, 242, 254,822

AIJ 2002 572

AIJ 2005 558

ANSI/AISC N690-1994 846

AS 4100 19

ASCE 10-97 816

B7 382

BS 5950-5 101

BS5400 93

BS5950 67

BSK 99 792

CSA CAN/CSA-S16-01 129

DIN 18800 414

DS412 201


Index: Steel Design per IS 800 – Young's Modulus

Eurocode 219, 222, 237-238, 240,242, 254

French Code 394

IS 800 2007 520

IS 802 490

IS801 512

NBE-MV103-1972 784

NEN 6770 207

NORSOK N-004 670

NS 3472 / NPD 616

NTC 1987 604

S136-94 165

SAB0162-1 1993 760

SNiP 2.23-81 726

Steel Design per IS 800 472

Steel Section Library

British 68

Japanese 572

Structural Steelwork 394

Design Rules 394

Swedish Codes 790

T

Timber Design

EC5 356

U

UK

National AnnexSee NationalAnnex, British

V

Verification Problem

AIJ 2005 567

ASME NF 3000 1974 892

ASME NF 3000 1989 904

ASME NF 3000 1998 918

ASME NF 3000 2004 930

British Cold Formed Steel 112

CSA 147, 150, 153, 156

CSA Wood 182

EC5 366, 370

SAB0162-1 773, 775, 778

W

Weld Type 80

Wood and Armer Moments 53, 99,197, 750

Wood Design

CAN/CSA-086-01 173

Y

Young's ModulusSee Modulus ofElasticity

941 — STAAD.Pro

Bentley Systems, Incorporated

685 Stockton Drive, Exton, PA 19341 USA

+1 (800) 236-8539

www.bentley.com


International Codes Staad Pro V8i

Documents

Transcript of International Codes Staad Pro V8i