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STAAD.Pro V8i (SELECTseries 2) International Design Codes Manual DAA037810-1/0003 Last updated: 6 March 2011

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STAAD.ProV8i (SELECTseries 2)

International Design Codes ManualDAA037810-1/0003 Last updated: 6 March 2011

Copyright InformationTRADEMARK NOTICEBentley, the "B" Bentley logo, STAAD.Pro are registered or nonregistered trademarks of Bentley Sytems, Inc. or Bentley Software, Inc. All other marks are the property of their respective owners.

COPYRIGHT NOTICE 2011, Bentley Systems, Incorporated. All Rights Reserved. Including software, file formats, and audiovisual displays; may only be used pursuant to applicable software license agreement; contains confidential and proprietary information of Bentley Systems, Incorporated and/or third parties which is protected by copyright and trade secret law and may not be provided or otherwise made available without proper authorization.

ACKNOWLEDGMENTSWindows, Vista, SQL Server, MSDE, .NET, DirectX are registered trademarks of Microsoft Corporation. Adobe, the Adobe logo, Acrobat, the Acrobat logo are registered trademarks of Adobe Systems Incorporated.

International Design Codes Manual i

RESTRICTED RIGHTS LEGENDSIf this software is acquired for or on behalf of the United States of America, its agencies and/or instrumentalities ("U.S. Government"), it is provided with restricted rights. This software and accompanying documentation are "commercial computer software" and "commercial computer 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 and accompanying documentation by the U.S. Government are subject to restrictions as set forth in this Agreement and pursuant to 48 C.F.R. 12.212, 52.227-19, 227.7202, and 1852.227-86, as applicable. Contractor/Manufacturer is Bentley Systems, Incorporated, 685 Stockton Drive, Exton, PA 19341- 0678. Unpublished - rights reserved under the Copyright Laws of the United States and International treaties.

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

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Table of ContentsAbout STAAD.Pro About the STAAD.Pro DocumentationGetting Started and Tutorials Examples Manual Graphical Environment Technical Reference Manual International Design Codes

2 44 4 4 4 5

Section 1 Australian CodesAustralian Codes - Concrete Design per AS 3600 - 2001 Australian Codes - Steel Design per AS 4100 - 1998

79 19

Section 2 British CodesBritish Codes - Concrete Design per BS8110 British Codes - Steel Design per BS5950:2000 British Codes - Design per BS5400 British Codes - Design per BS8007 British Codes - Design per British Cold Formed Steel Code

5759 81 113 119 123

International Design Codes Manual iii

Section 3 Canadian Codes

153155 163 207 215

Canadian Codes - Concrete Design per CSA Standard A23.3-94 Canadian Codes - Steel Design per CSA Standard CAN/CSAS16-01 Canadian Codes - Design Per Canadian Cold Formed Steel Code S136-94 Canadian Codes - Wood Design Per CSA Standard CAN/CSA086-01

Section 4 Chinese CodesChinese Codes - Concrete Design Per GB50010-2002 Chinese Codes - Steel Design Per GBJ 50017-2003

247249 261

Section 5 European CodesEuropean Codes - Concrete Design Per Eurocode EC2 European Codes - Steel Design Per Eurocode 3 5B.5(B).4.1 Basic stress check 5B.5(B).4.2 Detailed stress check European Codes - Timber Design Per EC 5: Part 1-1

273275 283 313 316 405

Section 6 Egyptian CodesEgyptian Codes - Concrete Design Per Egyptian Code ECCS203 Egyptian Codes - Steel Design Per Egyptian Code # 205

431433 441

Section 7 French CodesFrench Codes - ConcreteDesign per B.A.E.L French Codes - SteelDesign per the French Code

451453 459

Section 8 German CodesGerman Codes - ConcreteDesign Per DIN 1045 iv STAAD.Pro

471473

German Codes - SteelDesign Per the DIN Code

481

Section 9 Indian CodesIndian Codes - Concrete Design per IS456 Indian Codes - Concrete Design per IS13920 Indian Codes - Steel Design per IS800:1984 Indian Codes - Steel Design per IS802 Indian Codes - Design per Indian Cold Formed Steel Code

493495 521 547 569 593

Section 10 Japanese CodesJapanese Codes - ConcreteDesign Per 1991 AIJ Japanese Codes - SteelDesign Per 2005 AIJ

601603 613

Section 11 Mexican CodesMexican Codes - Concrete Design Per MEX NTC 1987 Mexican Codes - Steel Design Per Mexican Code

649651 669

Section 12 Russian CodesRussian Codes - Concrete Design Per Russian Code (SNiP 2.03.01-84*)

683685

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

Section 13 South African CodesSouth African Codes - Concrete Design Per SABS-0100-1

737739

South African Codes - Steel Design Per SAB Standard SAB01621:1993 747

Section 14 American Aluminum Code Section 15 American Transmission Tower CodeAmerican Transmission Tower Code - Steel Design per ASCE 10-97

773 791793

International Design Codes Manual v

American Transmission Tower Code - Steel Design per ASCE Manuals and Reports

801

Section 16 Steel Design per American Petroleum Institute Code 807 Section 17 ANSI/AISC N690 Design CodesANSI/AISC N690-1994 Code ANSI/AISC N690-1984 Code

823825 845

Section 18 American Society of Mechanical Engineers Nuclear Facility (ASME NF) Codes 869ASME NF 3000 - 1974 & 1977 Codes ASME NF 3000 - 1989 Code ASME NF 3000 - 2004 Code ASME NF 3000 - 2004 Code 871 883 897 910

Section 19 Norwegian CodesNorwegian Codes - Steel Design per NS 3472 / NPD Norwegian Codes - Steel Design per NORSOK N-004 Norwegian Codes - Concrete Design per NS 3473

923925 983 1008

Section 20 Cypriot CodesCypriot Codes - Concrete Design in Cyprus

10131013

Section 21 Danish CodesDanish Codes - Steel Design per DS412

10191019

Section 22 Dutch CodesDutch Codes - Steel Design per NEN 6770

10231023

Section 23 Finnish CodesFinnish Codes - Concrete Design per B4 Finnish Codes - Steel Design per B7 vi STAAD.Pro

10271027 1030

Section 24 Singaporian CodesSingaporean Codes - Concrete Design per CP65

10351035

Section 25 Spanish CodesSpanish Codes - Concrete Design per EHE

10411041

Section 26 Swedish CodesSwedish Codes - Concrete Design per BBK 94

10451045

Technical Support Index

1049 1051

International Design Codes Manual vii

This documentation has been prepared to provide information pertaining to the various international codes supported by STAAD. These codes are provided as additional codes by Research Engineers. In other words, they do not come with the standard package. Hence, information on only some of the codes presented in this document may be actually pertinent to the individual user's package. This document is to be used in conjunction with the STAAD Technical Reference Manual and the STAAD Application Examples Manual. Effort has been made to provide some basic information about the analysis considerations and the logic used in the design approach. A brief outline of the factors affecting the design along with references to the corresponding clauses in the codes is also provided. Examples are provided at the appropriate places to facilitate ease of understanding of the usage of the commands and design parameters. Users are urged to refer to the Examples Manual for solved problems that use the commands and features of STAAD. Since the STAAD output contains references to the clauses in the code that govern the design, users are urged to consult the documentation of the code of that country 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 applications primarily 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 following facilities to enable this task. 1. Graphical model generation utilities as well as text editor based commands for creating the mathematical model. Beam and column members are represented using lines. Walls, slabs and panel type entities are represented using triangular and quadrilateral finite elements. Solid blocks are represented using brick elements. These utilities allow the user to create the geometry, assign properties, orient cross sections as desired, assign materials like steel, concrete, timber, aluminum, specify supports, apply loads explicitly as well as have the program generate loads, design parameters etc. 2. Analysis engines for performing linear elastic and pdelta analysis, finite element analysis, frequency extraction, and dynamic response (spectrum, time history, steady state, etc.). 3. Design engines for code checking and optimization of steel, aluminum and timber members. Reinforcement calculations for concrete beams, columns, slabs and shear walls. Design of shear and moment connections for steel members. 4. Result viewing, result verification and report generation tools for examining displacement diagrams, bending moment and shear force diagrams, beam, plate and solid stress contours, etc. 5. Peripheral tools for activities like import and export of data from and to other widely accepted formats, links with other popular softwares for niche areas like reinforced and prestressed concrete slab design, footing design, steel connection design, etc. 6. A library of exposed functions called OpenSTAAD which allows users to access STAAD.Pros internal functions and routines as well as its graphical commands to tap into STAADs database and link input and output data to third-party software written using languages like C, C++, VB, VBA,

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

International Design Codes Manual 3

About the STAAD.Pro DocumentationThe documentation for STAAD.Pro consists of a set of manuals as described below. These manuals are normally provided only in the electronic format. All the manuals can be accessed from the Help facilities of STAAD.Pro. If you want to obtain a 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 print them 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, computer system requirements, installation process, copy protection issues and a description on how to run the programs in the package. Tutorials that provide detailed and step-by-step explanation on using the programs are also provided.

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

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

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

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International Design CodesThis document contains information on the various Concrete, Steel, and Aluminum design codes, of several countries, that are implemented in STAAD. The documentation for the STAAD.Pro Extension component(s) is available separately.

International Design Codes Manual 5

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Section 1

Australian Codes

International Design Codes Manual 7

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Australian Codes - Concrete Design per AS 3600 - 20011A.1 Design OperationsSTAAD has the capabilities for performing concrete design based on the Australian code AS 3600-2001 Australian Standard-Concrete Structures.

1A.2 Section Types for Concrete DesignThe following types of cross sections for concrete members can be designed.l

For Beams: Prismatic (Rectangular & Square) For Columns: Prismatic (Rectangular, Square, and Circular)

l

1A.3 Member DimensionsConcrete members which will be designed by the program must have certain section properties input under the MEMBER PROPERTY command. The following example shows the required input:UNIT MM MEMBER PROPERTY 1 3 TO 7 9 PRISM YD 450. ZD 250. 11 13 PR YD 350.

In the above input, the first set of members are rectangular (450 mm depth and 250mm width) and the second set of members, with only depth and no width provided, will be assumed to be circular with 350 mm diameter. It is absolutely imperative that the user not provide the cross section area (AX) as an input.

1A.4 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 for conventional design requirements. These values may be changed to suit the particular design being performed. Table 1A.1 of this manual contains a complete list of the available parameters and their default values. It is necessary to

International Design Codes Manual 9

Australian Codes - Concrete Design per AS 3600 - 2001

declare length and force units as Millimeter and Newton before performing the concrete design. Note: 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. Table 1A.1 - Australian Concrete Design per AS 3600 Parameters Parameter Name CODE Default Value Description Must be specified as AUSTRALIAN to invokes design per AS 3600 2001. Design Code to follow. See section 5.52.2 of the Technical Reference Manual. CLEAR 25 mm 40 mm DEPTH YD For beam members. For column members Total depth to be used for design. This value defaults to YD as provided under MEMBER PROPERTIES.

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Parameter Name FMC

Default Value 40 N/mm2

Description Concrete Yield Stress. Applicable values per Clause 6.1.1.1 of AS 3600-2001: 20 25 32 40 50 65

FYMAIN

450 N/mm2

Yield Stress for main reinforcing steel. Applicable values per Table 6.2.1 of AS 36002001: 250 400 450 500

FYSEC

450 N/mm2

Yield Stress for secondary reinforcing steel. Applicable values per Table 6.2.1 of AS 3600-2001: 250 400 450 500

International Design Codes Manual 11

Australian Codes - Concrete Design per AS 3600 - 2001 Parameter Name MAXMAIN MINMAIN MAXSEC MINSEC RATIO Default Value 60 mm 10 mm 12 mm 8 mm 4.0 Description Maximum main reinforcement bar size. Minimum main reinforcement bar size. Maximum secondary reinforcement bar size. Minimum secondary reinforcement bar size. Maximum percentage of longitudinal reinforcement in columns. Tied column. A value of 1.0 will mean spiral reinforcement.

REINF

0.0

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Parameter Name TRACK

Default Value 0.0

Description BEAM DESIGN: For TRACK = 0.0, output consists of reinforcement details at START, MIDDLE and END. For TRACK = 1.0, critical moments are printed in addition to TRACK 0.0 output. For TRACK = 2.0, required steel for intermediate sections defined by NSECTION are printed in addition to TRACK 1.0 output. COLUMN DESIGN: With TRACK = 0.0, reinforcement details are printed.

International Design Codes Manual 13

Australian Codes - Concrete Design per AS 3600 - 2001 Parameter Name WIDTH Default Value ZD Description Width to be used for design. This value defaults to ZD as provided under MEMBER PROPERTIES.

1A.5 Slenderness Effects and Analysis ConsiderationSlenderness effects are extremely important in designing compression members. There are two options by which the slenderness effect can be accommodated. One option is to perform an exact analysis which will take into account the influence of axial loads and variable moment of inertia on member stiffness and fixed end moments, the effect of deflections on moment and forces and the effect of the duration of loads. Another option is to approximately magnify design moments. STAAD has been written to allow the use of the first option. To perform this type of analysis, use the command PDELTA ANALYSIS instead of PERFORM ANALYSIS. The PDELTA ANALYSIS will 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 safely ignored because experts believe that the effects of the duration of loads are negligible in a normal structural configuration. Although ignoring load duration effects is somewhat of an approximation, it must be realized that 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 PDELTA ANALYSIS, as performed by STAAD may be used for the design of concrete members. However the user must note that to take advantage of this analysis, all the combinations of loading must be provided as primary load cases and not as load combinations. This is due to 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 the user. STAAD does not factor the loads automatically.

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

Design for FlexureMaximum 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 each of the above mentioned sections. Each of these sections is designed to resist both of these critical sagging and hogging moments. Currently, design of singly reinforced sections only is permitted. If the section dimensions are inadequate as a singly reinforced section, such a message 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 single layer of assumed reinforcement and reinforcement requirements are calculated. After the preliminary design, reinforcing bars are chosen from the internal database in single or multiple layers. The entire flexure design is performed again in a second pass taking into account the changed effective depths of sections calculated on the basis of reinforcement provided after the preliminary design. Final provisions of flexural reinforcements are made then. Efforts have been made 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 will be 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 sections from which the final detailed drawing can be prepared.

Design for ShearShear reinforcement is calculated to resist both shear forces and torsional moments. Shear design is performed at 13 equally spaced sections (0. to 1.) for the maximum shear forces amongst the active load cases and the associated torsional moments. Shear capacity calculation at different sections without the shear reinforcement is based on the actual tensile reinforcement provided by STAAD. Two-legged stirrups are provided to take care of the balance shear forces acting on these sections. Example of Input Data for Beam Design: International Design Codes Manual 15

Australian Codes - Concrete Design per AS 3600 - 2001

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.7 Column DesignColumns are designed for axial forces and biaxial moments at the ends. All active load cases are tested to calculate reinforcement. The loading which yields maximum reinforcement is called the critical load. Column design is done for square, rectangular and circular sections. By default, square and rectangular columns are designed with reinforcement distributed on each 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 selecting longitudinal and transverse reinforcement as stipulated by AS 3600 have been taken care of in the column design of STAAD. Example of Input Data for Column Design:UNIT NEWTON MMS START CONCRETE DESIGN CODE AUSTRALIAN FYMAIN 415 ALL FC 35 ALL CLEAR 25 MEMB 2 TO 6 MAXMAIN 40 MEMB 2 TO 6 DESIGN COLUMN 2 TO 6

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END CONCRETE DESIGN

1A.8 Slab/Wall DesignTo design a slab or wall, it must be modeled using finite elements. The command specifications 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 the element force output (see Section 3.8 of the Technical Reference Manual). The reinforcement required to resist Mx moment is denoted as longitudinal reinforcement and the reinforcement required to resist My moment is denoted as transverse reinforcement. The parameters FYMAIN, FC, MAXMAIN, MINMAIN, and CLEAR listed in Table 1A.1 are relevant to slab design. Other parameters mentioned in Table 1A.1 are not applicable to slab design.Figure 1.1 - Element moments: Longitudinal (L) and Transverse (T)

Example of Input Data for Slab/Wall DesignUNIT NEWTON MMS START CONCRETE DESIGN CODE AUSTRALIAN FYMAIN 415 ALL FC 25 ALL CLEAR 40 ALL DESIGN ELEMENT 15 TO 20

International Design Codes Manual 17

Australian Codes - Concrete Design per AS 3600 - 2001

END CONCRETE DESIGN

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Australian Codes - Steel Design per AS 4100 19981B.1 GeneralThis section presents some general statements regarding the implementation of the specifications recommended by Standards Australia for structural steel design (AS 4100 - 1998 Steel Structures) in STAAD. The design philosophy and procedural logistics are based on the principles of elastic analysis and limit state method of design. Facilities are available for member selection as well as code checking. The design philosophy embodied in this specification is based on the concept of limit state design. Structures are designed and proportioned taking into consideration the limit states at which they would become unfit for their intended use. Two major categories of limit-state are recognized - ultimate and serviceability. The primary considerations in ultimate limit state design are strength and stability, while that in serviceability is deflection. Appropriate load and resistance factors are used so that a uniform reliability is achieved for all steel structures under various loading conditions and at the same time the chances of limits being surpassed are acceptably remote. In the STAAD implementation, members are proportioned to resist the design loads without exceeding the limit states of strength, stability, and serviceability. Accordingly, the most economic section is selected on the basis of the least weight criteria as augmented by the designer in specification of allowable member depths, desired section type, or other such parameters. The code checking portion of the program checks whether code requirements for each 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 and assumptions is available in the specification document.

Strength Limit StatesStrength design capacities (Ru) are calculated and compared to user-defined design action effects (S*), so as to ensure that S* Ru in accordance with AS 4100 3.4. Details for design capacity calculations are outlined in the sections that follow.

International Design Codes Manual 19

Australian Codes - Steel Design per AS 4100 - 1998

Deflection Limit StatesSTAAD.Pros AS 4100 implementation does not generally check deflections. It is left to the user 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 against a user-defined maximum span / deflection ratio. This can be performed using the DFF, DJ1, and DJ2 design parameters, however this is only available for MEMBER Design. Details are provided in the sections that follow.

Eccentric Beam ReactionsSTAAD.Pro does not automatically account for minimum eccentricity distances for beam reactions being transferred to columns as per AS 4100 4.3.4. However member offsets can be used to model these eccentricities. Refer to Section 5.25 for further information on the Member Offset feature.

Limit States Not ConsideredThe following limit states are not directly considered in STAAD.Pros implementation of AS 4100. Table 1B.1 - Limit States Not Considered in STAAD.Pro AS 4100 Design Limit State Code Reference AS 4100 3.3 AS 4100 3.5 AS 4100 3.7 AS4100

Stability Serviceability Brittle Fracture Fire

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Limit State

Code Reference 3.9

Other Design Requirements

AS 4100 3.11

Connection DesignSTAAD.Pro and Bentleys RAM Connection program currently do not support design of connections in accordance with AS 4100. In some cases connection design may govern the size of members. Such considerations are not considered in STAAD.Pros AS 4100 and should be checked by separately.

Bolts and WeldsBolt holes and welds are not generally considered in STAAD.Pros AS 4100 member design. Note: NSC and NSF design parameters are used to manually specify a reduction in net section area for compression or tension capacity calculations. These can be used to account for bolt hole area reductions. Further details are provided in the sections that follow.

1B.2 Analysis MethodologyEither the elastic or dynamic analysis methods may be used to obtain the forces and moments for design as per AS4100 section 4.4. Analysis is done for the specified primary and repeat loading conditions. Therefore, it is your responsibility to enter all necessary loads and load combination factors for design in accordance with the AS/NZS 1170 Series or other relevant design codes. You are allowed complete flexibility in providing loading specifications and using appropriate load factors to create necessary loading situations. Depending upon the analysis requirements, regular stiffness analysis or P-Delta analysis may be specified. Dynamic analysis 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 not implemented in STAAD.Pro.

International Design Codes Manual 21

Australian Codes - Steel Design per AS 4100 - 1998

Elastic AnalysisTwo types of elastic analysis can be performed using STAAD.Pro in accordance with AS4100: i. First Order Linear, Elastic Analysis - used to perform a regular elastic stiffness analysis as per AS 4100 4.4.2.1. Refer to Section 5.37.1 of the Technical Reference Manual for additional details on this feature. ii. Second Order PDelta Linear, Elastic Analysis - Depending on the type of structure, a PDelta analysis may be required in order to capture secondorder effects as per AS 4100 4.4.1.2. Second-order effects can be captured in STAAD.Pro by performing a PDelta second-order elastic analysis as per AS 4100 Appendix E. Refer to Section 5.37.2 of the Technical 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 cases using a PDelta Analysis, the Repeat Load feature must be used. Second-order effects will not be correctly evaluated if the Load Combination feature is used. Load Combinations are combinations of results where Repeat Loads instruct the program to perform the analysis on the combined load actions. Refer to Section 5.32.11 of the Technical Reference Manual for additional details on using Repeat Loads.

Dynamic AnalysisDynamic 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 Dynamic Loading and Analysis features.

1B.3 Member Property SpecificationsFor specification of member properties, either the steel section library available in STAAD or the User Table facility may be used. The next section describes the syntax of commands used to assign properties from the built-in steel table. For

22 STAAD.Pro

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 be referenced 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 into these tables, shear deformation is always considered during the analysis of these members. An example of the member property specification in an input file is provided at the end of this section. A complete listing of the sections available in the built-in steel section library may be obtained by using the tools of the graphical user interface. Refer to Section 1.7.2 of the Technical Reference Manual for additional information. Table 1B.2 - Available Australian Sections for STAAD.Pro AS 4100 Design General Profile Type I-SECTION Australian Sections WB, WC UB, UC T-SECTION CHANNEL ANGLE TUBE PIPE BT, CT PFC EA, UA SHS, RHS CHS Description

Welded beams and columns Universal beams and columns Tees cut from universal beams and columns Parallel flange channels Equal and unequal angles Square and rectangular hollow sections Circular hollow sections

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), and Top & Bottom Cover Plates (TB), Double Channels (D, BA, & FR) and Double Angles (LD & SD). Refer to Section Profile Tables in the Graphical Environment for these options.

International Design Codes Manual 23

Australian Codes - Steel Design per AS 4100 - 1998

Hint: When adding and assigning sections using the built-in steel section library through the Graphical Environment, STAAD.Pros default tables are American. To change the default tables to Australian, select File > Configuration from the STAAD.Pro Start page (no input file open). Set the Default Profile Table to Australian on the Configure Program dialog Section Profile Table. Following are the descriptions of different types of sections.

UB ShapesThese shapes are designated in the following way.20 TO 30 TA ST UB150X14.0 36 TO 46 TA ST UB180X16.1

UC ShapesThe designation for the UC shapes is similar to that for the UB shapes.25 TO 35 TA ST UC100X14.8 23 56 TA ST UC310X96.8

Welded BeamsWelded Beams are designated in the following way.25 TO 35 TA ST WB700X115 23 56 TA ST WB1200X455

Welded ColumnsWelded Columns are designated in the following way.25 TO 35 TA ST WC400X114 23 56 TA ST WC400X303

24 STAAD.Pro

Parallel Flange ChannelsShown below is the syntax for assigning names of channel sections.1 TO 5 TA ST PFC75 6 TO 10 TA ST PFC380

Double ChannelsBack-to-back double channels, with or without a spacing between them, are available. The letter D in front of the section name will specify a double channel.11 TA D PFC230 17 TA D C230X75X25 SP 0.5

In the above set of commands, member 11 is a back-to-back double channel PFC230 with no spacing in between. Member 17 is a double channel PFC300 with a spacing of 0.5 length units between the channels.

AnglesTwo types of specification may be used to describe an angle. The standard angle section is specified 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 zz axis specified in Chapter 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 YZ Axis) in order to be designed to AS 4100. This is to ensure that the major and minor principal axes align with the local member z and y axes respectively, similar to other section profiles.

International Design Codes Manual 25

Australian Codes - Steel Design per AS 4100 - 1998

Double AnglesShort leg back-to-back or long leg back-to-back double angles can be specified by means of input 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

Tubes (Rectangular or Square Hollow Sections)Tubes can be assigned in 2 ways. In the first method, the designation for the tube is as shown below. This method is meant for tubes whose property name is available in the steel table. In these examples, members 1 to 5 consist of a 2X2X0.5 inch size tube section, and members 6 to 10 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,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 of 0.5 length units. Only code checking, no member selection, will be performed for TUBE sections specified in this latter manner.

Pipes (Circular Hollow Sections)Pipes can be assigned in 2 ways. In the first method, the designation for the pipe is as shown below. This method is meant for pipes whose property name is available in the steel table.1 TO 5 TA ST PIP180X5

26 STAAD.Pro

6 TO 10 TA ST PIP273X6.5

In the second method, pipe sections may be provided by specifying the word PIPE followed by the outside and inside diameters of the section. For example,1 TO 9 TA ST PIPE OD 25.0 ID 20.0

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

Sample File Containing Australian ShapesSTAAD 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

International Design Codes Manual 27

Australian Codes - Steel Design per AS 4100 - 1998

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) 9 TA ST TUBE DT 8.0 WT 6.0 TH 0.5 * 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, local buckling becomes an important criterion. Steel sections are classified as compact, noncompact, or slender; depending upon their local buckling characteristics. This classification is a function of the geometric properties of the section. The design procedures are different depending on the section class. STAAD determines the section classification for the standard shapes and user specified shapes. Design is performed for all three categories of section 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-in Material Constants feature. Refer Section 2.26.1 of the Technical Reference Manual for further information on the Define Material feature.

28 STAAD.Pro

Youngs Modulus of Elasticity (E)STAAD.Pros default steel materials E value is 205,000 MPa. However AS 4100 section 1.4 states that the modulus of elasticity should be taken as 200,000 MPa. There are a number of options to change this value:l

change the steel material through the input file or GUI for each file created define a new steel material for each file created change the default STAAD.Pro metric E value in the file C:/WINDOWS/STAADPRO20070.INI, going to the [Material-Metric] section, and changing 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 require additional files to be modified. Contact Bentley Technical Support for assistance.

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1B.7 Member ResistancesThe member resistance is calculated in STAAD according to the procedures outlined in AS 4100. Calculated design capacities are compared to corresponding axial, bending moment, and shear forces determined from the STAAD.Pro analysis. These are used to report the fail or pass status for the members designed. Two types of design checks are typically performed per AS 4100:l

Nominal section checks Nominal member checks

l

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 member capacity on the other hand refers to the capacity of a member to resist applied loads, and includes checks for global member buckling effects including Euler buckling, lateral-torsional buckling, etc.

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

International Design Codes Manual 29

Australian Codes - Steel Design per AS 4100 - 1998

intended to prevent excessive elongation of the member. The second limit state involves fracture at the section with the minimum effective net area N section axial tension capacities are calculated (Cl.7.2). Through the t use of the NSF parameter (see Table 1B.1), you may specify the net section area. STAAD calculates the tension capacity of a member based on these two limit states per Cl.7.1 and Cl.7.2 respectively of AS 4100. Eccentric end connections can be taken into account using the KT correction factor, perCl.7.3. The f yield stress is y based on the minimum plate yield stress. Parameters FYLD, FU, and NSF are applicable for these calculations.

Axial CompressionThe compressive strength of members is based on limit states per AS 4100 Section 6. It is taken as the lesser of nominal section capacity and nominal member capacity. Nominal section capacity, N , is a function of form factor (Cl.6.2.2), net s area of the cross section, and yield stress of the material. Through the use of the NSC parameter (see Table 1B.1), you may specify the net section area. Note that this parameter is different from that corresponding to tension. The program automatically calculates the form factor. The k form factors are calculated based f on effective plate widths per Cl.6.2.4, and the f yield stress is based on the y minimum plate yield stress. Nominal member capacity, N , is a function of nominal section capacity and c member slenderness reduction factor (Cl.6.3.3). This value is calculated about both principal x and y axes. Here, you are required to supply the value of b (Cl.6.3.3) through the ALBparameter (see Table 1B.1). The effective length for the calculation of compressive strength may be provided through the use of the parameters KY, KZ, LY, and LZ (see Table 1B.1).

BendingBending capacities are calculated to AS 4100 Section 5. The allowable bending moment of members is determined as the lesser of nominal section capacity and nominal member capacity (ref. Cl.5.1). The nominal section moment capacity, M , is calculated about both principal x s and y axes and is the capacity to resist cross-section yielding or local buckling and is expressed as the product of the yield stress of the material and the effective section modulus (ref. Cl.5.2). The effective section modulus is a function of section type (i.e., compact, noncompact, or slender) and minimum plate yield stress f .y

30 STAAD.Pro

The nominal member capacity depends on overall flexural-torsional buckling of the member (ref.Cl.5.3). Note: For sections where the web and flange yield stresses (f and f y,web y.flange respectively) are different, the lower of the two yield stresses is applied to both the web and flange to determine the slenderness of these elements. Member moment capacity, M , is calculated about the principal x axis only (ref. b Cl.5.6). Critical flange effective cross-section restraints and corresponding design segment and sub-segments are used as the basis for calculating capacities.

Interaction of Axial Force and BendingCombined section bending and shear capacities are calculated using the shear and bending interaction method as per Cl.5.12.3. Note: This check is only carried out where V section web shear capacities are v calculated. Refer Table 1B.6-1 for details. The member strength for sections subjected to axial compression and uniaxial or biaxial bending is obtained through the use of interaction equations. Here, the adequacy of a member 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 of the left hand side of the equations, addressed by the above clauses, exceeds 1.0 or the allowable value provided using the RATIO parameter (see Table 1B.1), the member is considered to have FAILed under the loading condition.

ShearSection web shear capacity, V , is calculated per Cl.5.11, including both shear v yield and shear buckling capacities. Once the capacity is obtained, the ratio of the shear force acting on the cross section to the shear capacity 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 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.

International Design Codes Manual 31

Australian Codes - Steel Design per AS 4100 - 1998 Table 1B.3 - Section Type Shear Checks General Profile Type Australian Section WB, WC, UB, UC Shear Checks

I-SECTION (i.e., parallel to minor principal y-axis) T-SECTION CHANNEL ANGLE TUBE PIPE

Calculated for web only

BT, CT PFC EA, UA SHS, RHS CHS No checks performed Calculated parallel to both x & y principal axes Per AS 4100 5.11.4

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

TorsionSTAAD.Pro does not design sections or members for torsion for AS4100.

1B.8 Design ParametersThe design parameters outlined in Table 1B.1 are used to control the design procedure. These parameters communicate design decisions from the engineer to the program and thus allow the engineer to control the design process to suit an application's specific needs. The design scope 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 numbers for conventional design. Depending on the particular design requirements, some or all of these parameter values may be changed to exactly model the physical structure. Note: 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.

32 STAAD.Pro

Table 1B.4 - Australian Steel Design Parameters Parameter Name CODE Default Value Design Scope Description

-

Must be specified as AUSTRALIAN to invoke design per AS 4100 - 1998. Design Code to follow. See section 5.48.1 of the Technical Reference Manual.

ALB

0.0

Member section constant (refer cl. 6.3.3) If ALB is 0.0, it is automatically calculated based on TABLE 6.3.3(1), 6.3.3(2); otherwise the input value is used.

ALM

0.0

Moment modification factor (refer cl. 5.6.1.1) If ALM is 0.0, it is automatically calculated based cl.5.6.1.1; otherwise the input value is used.

BEAM

0.0

0.0 = design only for end moments and those at locations specified by SECTION

International Design Codes Manual 33

Australian Codes - Steel Design per AS 4100 - 1998 Parameter Name Default Value Design Scope Description

command. 1.0 = Perform design for moments at twelfth points along the beam. DFF None (Mandatory for deflection check) Start Joint of member Analytical Deflection Length/ members Maximum Allowable only local deflection. Joint No. denoting start point for calculation of deflection length Joint No. denoting end point for calculation of deflection length Maximum allowable depth (Applicable for member selection) Minimum required depth (Applicable for member selection) Physical Used to specify the members type of end cononly nection to account for eccentric connection effects for compression and tension members. Steel type - 1 - SR, 2 - HR, 3 - CF, 4 -

DJ1

DJ2

End Joint of member

DMAX

45.0 [in.]

DMIN

0.0 [in.]

EEC

0.0

IST

1

34 STAAD.Pro

Parameter Name

Default Value

Design Scope

Description

LW, 5 - HW FU FYLD KT 500.0 [MPa] 250.0 [MPa] 1.0 Ultimate strength of steel. Yield strength of steel. Correction factor for distribution of forces (refer cl. 7.2) K value for general column flexural buckling about the local Y-axis. Used to calculate slenderness ratio. K value for general column flexural buckling about the local Z-axis. Used to calculate slenderness ratio. Physical Load height position members as described in Table only 5.6.3(2)of AS 4100:1998 0 = at Shear center 1 = At top flange LY Member Length Length for general column flexural

KY

1.0

KZ

1.0

LHT

0

International Design Codes Manual 35

Australian Codes - Steel Design per AS 4100 - 1998 Parameter Name Default Value Design Scope Description

buckling about the local Y-axis. Used to calculate slenderness ratio. LZ Member Length Length for general column flexural buckling about the local Z-axis. Used to calculate slenderness ratio. 0.0 = Check slenderness ratio against the limits.l

MAIN

0.0

Default limit for compression = 180.0 Default limit in tension = 400.0

l

1.0 = Suppress the slenderness ratio check. Any value greater than 1.0 is used as the limit for slenderness in compression. NSC 1.0 Net section factor for compression members = An / Ag (refer cl. 6.2.1)

36 STAAD.Pro

Parameter Name NSF PBRACE

Default Value

Design Scope

Description

1.0 None

Net section factor for tension members. Physical Refer to section members 1B.11 for details on only the PBRACE parameter. Capacity reduction factor Permissible ratio of actual load effect to the design strength. Steel Grade. Refer to Note a below. 0= Normal grade 1 = High strength grade of steel

PHI RATIO

0.9 1.0

SGR

0

SKT

1.0

A twist restraint factor given in Table 5.6.3(1) A load height factor given in Table 5.6.3(2) A lateral rotation restraint factor given in Table 5.6.3(3) Physical Used to specify members whether eccentric only

SKL

1.0

SKR

1.0

TEE

0.0

International Design Codes Manual 37

Australian Codes - Steel Design per AS 4100 - 1998 Parameter Name Default Value Design Scope Description

effects for tension members are checked based on simplified kt corrections factors to AS 4100 7.3.2, or by using calculated eccentric moments in combination with axial tension per AS 4100 Section 8. TMAIN 180.0 Slenderness limit in tension. Slenderness limit is checked based MAIN parameter. Output detail 0.0 = Report only minimum design results. 1.0 = Report design strengths also. 2.0 = Provide full details of design. UNB Member Length Unsupported length

TRACK

0.0

38 STAAD.Pro

Parameter Name

Default Value

Design Scope

Description

in bending compression of the bottom flange for calculating moment resistance.

UNT

Member Length

Unsupported length in bending compression of the top flange for calculating moment resistance.

Notesa. Deflection calculations

b. LHT Parameter If the shear force is constant within the segment, longitudinal position of the load is assumed to be at the segment end. If there is any variation of the shear force and the load is acting downward determined from shear force variation and load height parameter indicates the load is acting on top flange (flange at the positive local y axis) and restraints at the end of the segment is not FU (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 determined from shear force variation and load height parameter indicates the load is acting on top flange (flange at the positive local y axis) and restraints at the end of the segment is not FU (FRU) or PU (PRU) Kl is assumed to be 1.0 as the load acting at the top flange is contributing to stabilize against local torsional buckling. c. SGR Parameter

International Design Codes Manual 39

Australian Codes - Steel Design per AS 4100 - 1998

AS 4100 defines the values of steel grades that are used as either normal steel or high grade steel. The following table explains the material values used when either option is specified for a particular shape: Table 1B.5 - Steel Grades used for the SGR Parameter Section Type SGR Value Steel Grade Used 300 400 300 350 250 350

WB, WC, Tee section cut from WB and WC WB, WC, Tee section cut from WB and WC

0 (Normal) 1 (High)

UB, UC, Tee section cut from UB and 0 (Normal) UC, EA, UA and all UPT sections UB, UC, Tee section cut from UB and UC, 1 (High) EA, UA and all UPT sections Pipe, Tube, CHS, RHS, SHS Pipe, Tube, CHS, RHS, SHS 0 (Normal) 1 (High)

Note: If a value for theFYLDparameter has been specified, then that value will be used. Otherwise, the SGR value will be used to determine the yeild strength and tensile strength values for the steel. based on maximum thickness of the individual elements of the section. Only for shear capacity calculation web thickness is used. Similarly, Tensile Strength is determined either from FU 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 strongly recommended to use the Physical member design capabilities for AS4100:PARAMETER 1 CODE AUSTRALIAN ALB 0.0 MEMBER ALL

40 STAAD.Pro

ALM 1.13 MEMBER ALL BEAM 1.0 MEMBER ALL DFF 250.0 MEMBER ALL DMAX 0.4 MEMBER ALL DMIN 0.25 MEMBER ALL FU 400.0 MEMBER ALL FYLD 310.0 MEMBER ALL IST 2.0 MEMBER ALL KT 0.85 MEMBER ALL KX 0.75 MEMBER ALL KY 1.0 MEMBER ALL LX 4.5 MEMBER ALL LY 6.0 MEMBER ALL MAIN 1.0 MEMBER ALL TMAIN 135.0 MEMBER ALL NSC 0.9 MEMBER ALL NSF 1.0 MEMBER ALL PHI 0.9 MEMBER ALL RATIO 0.9 MEMBER ALL SGR 1.0 MEMBER ALL SKT 1.0 MEMBER ALL SKL 1.0 MEMBER ALL SKR 1.0 MEMBER ALL TRACK 2.0 MEMBER ALL UNB 3.4 MEMBER ALL UNT 6.8 MEMBER ALL CHECK CODE MEMBER ALL

International Design Codes Manual 41

Australian Codes - Steel Design per AS 4100 - 1998

1B.9 Code CheckingThe purpose of code checking is to evaluate whether the provided section properties of the members are adequate for the specified loads as per AS 4100 requirements. Hint: The member selection facility can be used to instruct the program to select a different section if the specified section is found to be inadequate. Code checking for an analytical member is done using forces and moments at every twelfth point along the beam. The code checking output labels the 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 moments are also printed. The extent of detail of the output can be controlled by using the TRACK parameter. Refer to Section 2.5 of the Technical Reference Manual for general information on Code Checking. Refer to Section 5.48.2 of the Technical Reference Manual for details the specification of the Code Checking command. Example of commands for code checking:UNIT NEWTON METER PARAMETER CODE AUSTRALIAN FYLD 330E6 MEMB 3 4 NSF 0.85 ALL KY 1.2 MEMB 3 4 RATIO 0.9 ALL CHECK CODE MEMB 3 4

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

42 STAAD.Pro

Physical MembersFor physical members (PMEMBERs), code checks are performed at section stations positioned at 1/12th points along each analytical member included in the PMEMBER. It is up to you to determine if these locations cover critical sections for design, and adjust as necessary. The number of stations for PMEMBER Design cannot be altered, however the analytical members can be split so that in effect more stations are checked for a PMEMBER. For each section station along a PMEMBER, section capacity checks are carried for design actions 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 restraints and 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 member capacities. 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 at the section station are used. However when checking combined actions for the member 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 as the critical condition, critical load case, magnitudes of design actions for the most critical cross-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 the output. Color-coded results can also be viewed in the GUIs Post Processing Beam |Unity Check page. In some cases some of the output will report N/A values. This occurs where a calculation does not apply to a member. For example if a member never goes into tension then no values can be reported in the tension capacity output sections. Note: As per AS 4100 1.4, the TRACK 2.0 detailed level of output for PMEMBER Design uses 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 and minor principal axes.

International Design Codes Manual 43

Australian Codes - Steel Design per AS 4100 - 1998

1B.10 Member SelectionThis process incrementally checks increasing section profile sizes until a size is found that is AS 4100 compliant, or the largest section has been checked. Only section profiles of the same type as modeled are incrementally checked, with the increasing sizes based on a least weight per 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 limited to sections in the user table. Refer to Section 2.6 of the Technical Reference Manual for general information on Member Selection. Refer to Section 5.48.3 of the Technical Reference Manual for details the specification of the Member Selection command. The design calculations for Member Selection are the same as for Code Checking. Hint: A Fixed Group command is also available, and can be used to force all members within a user-defined group to take the same section size based on the most critical governing design criteria for all members within that group. This is particularly useful when you want to use the Member Selection feature, but want a group of elements to have the same size. Refer to Section 5.49 of the Technical Reference Manual for information on using this feature.

Note: Member Selection will change member sizes, and hence will change the structures stiffness matrix. In order to correctly account for this, a subsequent analysis and Code 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

44 STAAD.Pro

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 term CRITICAL 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 the requirements 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 the example in Section 1B.8. Physical Member (PMEMBER) Design on the other hand allows you to group single or multiple analytical members into a single physical design member for the purposes of design to AS 4100. PMEMBER Design also has additional features, including:l

automated steel grades based on section type; automated tensile stress (f ) and yield stress (f ) values based on plate thicku y nesses; automated segment / sub-segment design; improved detailed design calculation output; and

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

International Design Codes Manual 45

Australian Codes - Steel Design per AS 4100 - 1998

Modeling with Physical MembersPhysical Members may be grouped by either of the following methods:l

STAAD.Pro Editor - Directly specify physical members in the input file. Refer to Section 5.16.2 of the Technical Reference Manual for additional information. Graphical Environment - Using the tools in the Steel Design toolbar, members can be manually or automatically formed. Refer to Section 1.4 of the Graphical Environment manual for additional information.

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

Segment and Sub-Segment LayoutFor calculation of member bending capacities about the principal x-axis, the PMEMBER Design uses the concept of segment / sub-segment design. By default PMEMBERs are automatically broken up into design segments and sub-segments based on calculated effective restraints. User-defined restraints assigned using the PBRACE design parameter are checked 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 using the PBRACE design parameter, including available restraint types, and restraint layout rules. Note: Segment and sub-segment layouts for PMEMBERs may change for different load cases considered for design. Some restraints may be effective for one particular load case as they are found to apply to the critical flange, however for another load case may be found not to act on the critical flange, and found to be ineffective. In other words the critical flange can change 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).

46 STAAD.Pro

The PMEMBER Design uses the following routine to determine effective crosssection restraints for each load case considered: i. first all user-defined restraints are checked to see if they are applied to the compression flange, with those that arent ignored; ii. next a check is made to see if a U type restraint is found at either end of the PMEMBER. 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 the critical or non-critical flange. Refer AS 4100 5.4.2.4. The compression flange in step 1 of the routine above is calculated based on the bending moments at the locations of the restraints being considered. If the bending moment is zero at the same location as a restraint then the following method is used to determine which flange is critical at the zero moment location: a. If the zero moment is at the end of the PMEMBER, then the compression flange is based on the bending moment at a small increment from then end; b. If the zero moment is along the PMEMBER and is a peak value, then the compression flange 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 as outlined in Table 1B.9-3. Table 1B.6 - Assumed Order of Restraint Stiffness for Zero Moment Critical Flange Stiffness Most Stiff Restraint Type FR F PR P L U Least Stiff None

International Design Codes Manual 47

Australian Codes - Steel Design per AS 4100 - 1998

Once the effective restraints have been determined, the PMEMBER is divided into segments bounded by F, P, FR, PR or U effective restraints. These segments are then further divided into sub-segments by effective L restraints. Note: Sub-segment lengths are not automatically checked to determine if they provide full 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 both top and bottom flanges. Note: If the effective restraints for any load case consist of U or L restraints only, an error will be reported.

Physical Member Restraints SpecificationThe PBRACE parameter is used to specify the restraint condition along the top and bottom flange of a PMEMBER.

General FormatPBRACE { TOP | BOTTOM } f1 r1 f2 r2 f52 r52 (PMEMBpmemberlist) Where: f is a fraction of the PMEMBER length where restraint condition is n being specified. This value is any ratio between 0.0 and 1.0. r is one of the possible restraint condition as in the following:n

Table 1B.7 - Physical Member Restraint Types Designation, r1

Restraint Type Fully restrained Partially restrained

Description

F P

48 STAAD.Pro

Designation, r1

Restraint Type Laterally restrained Unrestrained

Description

L

Cannot be specified at the ends of design members. Can only be applied at the ends of design members, and must be applied to both flanges to be effective. Warning: Both top and bottom flanges can not be unrestrained at the same location (as this is unstable).

U

FR

Fully and rotationally restrained Partially and rotationally restrained Continuously The flange is assumed restrained to be continuously supported at that flange up to next restraint location. For continuously supported flange unbraced length is assumed to be zero.

PR

C

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

International Design Codes Manual 49

Australian Codes - Steel Design per AS 4100 - 1998

U PBRACE BOTTOM 0.75 L 0.0 U 0.25 P 0.5 L 1.0 U PMEMB 3 7

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

when gravity loads are dominant (i.e., negative local y-axis direction), the critical flange of a segment shall be the top flange (i.e., tension). when upward wind loads are dominant (i.e., positive local y-axis direction), the critical flange shall be the bottom flange (i.e., tension).

l

Design physical members are divided into segments by F, P, FR, PR or U effective section restraints. Segments are further broken down into sub-segments by L restraints, but only if the L restraints are deemed to be effective. L restraints are only considered to be effective when positioned on the critical flange between F, P, FR or FP restraints. If an L restraint is positioned 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, for both flanges.l

If UNL is not specified, segment length is used as UNL and used as L in effective length calculation as per 5.6.3. If ALM i.e., _m is not provided, automatic calculation of ALM is done based on moments within the segment. 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 at only 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. 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 and segment length.

l

l

l

50 STAAD.Pro

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 and shear force variation within the segment.

Notesa. If PMEMBER list is not provided, all the PMEMBERS are restrained by same configuration. b. It is not necessary to provide the restraint locations in sequence as the program sorts them automatically. c. Unless specified, PMEMBER ends are assumed to be Fully Restrained (F). d. While designing any section of the member, effective restraints are searched on each side of the section along the critical flange. e. The types of restraints applied to the top and bottom flanges at each location determines the effective section restraints. These are outlined in the table below: Table 1B.8 - Restraint Meanings in Critical and Noncritical Flanges Case Flange Restraint on a Critical Flange U 1 2 III 1 2 L Nothing P or F Nothing or U Restraint on a NonCritical Flange U Nothing L Nothing or U P or F Effective Section Restraint

I II

U L None F P

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Australian Codes - Steel Design per AS 4100 - 1998

Case

Flange

Restraint on a Critical Flange PR or FR Nothing or U L, P or F FR or PR

Restraint on a NonCritical Flange Nothing or U PR or FR L, P, F, FR or PR L, P, F, FR or PR

Effective Section Restraint

IV

1 2

FR PR F FR

V

1 2

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

Automated PMEMBER Design CalculationsThe AS 4100 PMEMBER Design automates many design calculations, including those required for segment / sub-segment design. Table 1B.9 - Automated PMEMBER AS 4100 Design Parameters and Calculations Automated PMEMBER Design CalDesign culations Parameter comb pression member section constant per AS 4100 6.3.3. moment m modification factor per AS 4100 ALB Comments

ALM

Calculated based on moments distribution for individual segments and sub-segments.

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Automated PMEMBER Design CalDesign culations Parameter 5.6.1.1. f tensile u strength per AS 4100 2.1.2. f yield stress y per AS 4100 2.1.1. residual stress category for AS 4100 Table 5.2 and AS 4100 Table 6.2.4. correction factor for distribution of forces in a tension member per AS 4100 7.3. Load height position for automated calculation of the kl load height factor per AS 4100 Table 5.6.3(2). FU

Comments

Based on nominal steel grade specified using SGR design parameter and section type. Based on nominal steel grade specified using SGR design parameter and section type. Based on section type.

FYLD

IST

KT

Based on section type and eccentric end connection specified using EEC design parameter.

LHT

LHT is used for automating calculation of kl load height factors for segments and sub-segments, per AS 4100 Table 5.6.3(2). When LHT is set to 1.0 to specify a top flange load height position, STAAD.Pro takes the top to be the positive local y-axis of the member. Note: This may not literally be

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Australian Codes - Steel Design per AS 4100 - 1998 Automated PMEMBER Design CalDesign culations Parameter Comments

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 in the 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 to be 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 / subsegment is considered. If the shear force is found to have the same direction and magnitude 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 or magnitudes, loads are assumed to act within the segment. Note: The above method includes an allowance for the self-weight of the member to be considered, as the self-weight always acts through the shear center.

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Automated PMEMBER Design CalDesign culations Parameter

Comments

The net sum of the end shears is also used to determine if the load is acting in the positive or negative local member y-axis direction. If LHT is set to 1.0 for top flange loading, the net sum is used to determine whether the top flange loading is acting to stabilise or destabilise the member for lateral torsional buckling. Negative local yaxis net loads act to destabilise the segments / sub-segments, whereas positive local y-axis net loads act to stabilise segments / sub-segments. Segment and sub-segment layout. Nominal steel grade. k twist t restraint factor as per AS 4100 Table 5.6.3(1). k load height l factor as per AS 4100 Table 5.6.3(2). k lateral rotar tion restraint factor as per AS 4100 PBRACE Refer to the Segment and Sub-Segment Layout section above for details. Based on section types. Based on effective end restraints for each segment / sub-segment.

SGR SKT

SKL

Based on effective end restraints for each segment / sub-segment, and LHT design parameter (refer above). Based on effective end restraints for each segment / sub-segment. This is where the distinction between F and FR, as well as P and PR is used.

SKR

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Australian Codes - Steel Design per AS 4100 - 1998 Automated PMEMBER Design CalDesign culations Parameter Table 5.6.3(3). Comments

ExamplePARAMETER 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

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Section 2

British Codes

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British Codes - Concrete Design per BS81102A.1 Design OperationsWarning: It is strongly recommended that you perform new concrete design using the RC Designer Module. The following is provided to allow old STAAD files to be run. STAAD has the capability of performing design of concrete beams, columns and slabs according to the 1997 revision of BS8110. Given the width and depth (or diameter for circular columns) of a section, STAAD will calculate the required reinforcement to resist the forces and moments.

2A.2 Design ParametersThe program contains a number of parameters which are needed to perform and control the design to BS8110. These parameters not only act as a method to input required data for code calculations but give the Engineer control over the actual design process. Default values of commonly 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. Note: 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. Table 2A.1 - British Concrete Design BS 8110 Parameters Parameter Name CODE Default Value Description

Must be specified as BRITISH to invoke design per BS8110. Design Code to follow. See section 5.52.2 of the Technical Reference Manual.

BRACE

0.0

0.0 = Column braced in both directions. 1.0 = Column unbraced about local Z

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British Codes - Concrete Design per BS8110 Parameter Name Default Value Description

direction only 2.0 = Column unbraced about local Y direction only 3.0 = Column unbraced in both Y and Z directions CLEAR 20 mm Clearance of reinforcement measured from concrete surface to closest bar perimeter, in current units. Depth of concrete member, in current units. This value default is as provided as YD in MEMBER PROPERTIES. Face of support location at end of beam, in current units. Note: Both SFACE & EFACE must be positive numbers. ELY ELZ FC FYMAIN 1.0 1.0 30 N/mm2 460 N/mm2 460 N/mm2 Member length factor about local Y direction for column design. Member length factor about local Z direction for column design. Concrete Yield Stress / cube strength, in current units Yield Stress for main reinforcement, in current units (For slabs, it is for reinforcement in both directions) Yield Stress for secondary reinforcement a, in current units. Applicable to shear bars in beams

DEPTH

YD

EFACE

0.0

FYSEC

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Parameter Name MAXMAIN

Default Value 50mm

Description

Maximum required reinforcement bar size Acceptable bars are per MINMAIN above. Minimum main reinforcement bar size Acceptable bar sizes: 6 8 10 12 16 20 25 32 40 50 Minimum secondary bar size a. Applicable to shear reinforcement in beams Factor by which column design moments are magnified Number of equally-spaced sections to be considered in finding critical moment for beam design. The upper limit is 20. Serviceability checks: 0.0 = No serviceability check performed. 1.0 = Perform serviceability check for beams as if they were continuous. 2.0 = Perform serviceability check for beams as if they were simply supported. 3.0 = Perform serviceability check for beams as if they were cantilever beams.

MINMAIN

8mm

MINSEC

8mm

MMAG NSECTION

1.0 10

SERV

0.0

SFACE

0.0

Face of support location at start of

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British Codes - Concrete Design per BS8110 Parameter Name Default Value Description

beam, in current units. (Only applicable for shear - use MEMBER OFFSET for bending ) SRA 0.0 0.0 = Orthogonal reinforcement layout without considering torsional moment Mxy -slabs only -500 = Orthogonal reinforcement layout with Mxy used to calculate Wood & Armer moments for design. A = skew angle considered in Wood & Armer equations where A is the angle in degrees. TRACK 0.0 0.0 = Critical Moment will not be printed with beam design report. Column design gives no detailed results. 1.0 = For beam gives min/max steel % and spacing. For columns gives a detailed table of output with additional moments calculated. 2.0 = Output of TRACK 1.0 List of design sag/hog moments and corresponding required steel area at each section of member WIDTH ZD Width of concrete member, in current units. This value default is as provided as ZD in MEMBER PROPERTIES.

2A.3 Slenderness Effects and Analysis ConsiderationsSTAAD provides the user with two methods of accounting for the slenderness effects in the analysis and design of concrete members. The first method is

62 STAAD.Pro

equivalent to the procedure presented in BS8110 Part 1 1985 Section 3.8.2.2 In this section, the code recognizes that additional 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 used in the design for concrete in STAAD. Alternatively STAAD houses a PDELTA ANALYSIS facility, which allows the effects of these second order moments to be considered in the analysis rather than the design. In a PDELTA analysis, after solving the joint displacements of the structure, the additional moments induced in the structure are calculated. These can be compared to those calculated using the formulation of BS8110.

2A.4 Member DimensionsConcrete members that are to be designed by STAAD must have certain section properties input under the MEMBER PROPERTIES command. The following example demonstrates the required 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 to be circular with 300mm diameter. Note that area (AX) is not provided for these members. If shear area areas ( AY & AZ ) are to be considered in analysis, the user may provide them along with YD and ZD. Also note that if moments of inertias are not provided, the program will calculate them from YD and ZD. Finally a T section can be considered by using the third definition above.

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British Codes - Concrete Design per BS8110

2A.5 Beam DesignBeam design includes both flexure and shear. For both types of beam action, all active beam loadings 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 the NSECTION parameter. From the critical moment values, the required positive and negative bar pattern is developed with cut-off lengths calculated to include required development length. Shear design as per BS8110 clause 3.4.5 has been followed and the procedure includes critical shear values plus torsional moments. From these values, stirrup sizes are calculated with proper spacing. The program will scan from each end of the member and provide a total of two shear regions at each, depending on the change of shear distribution along the beam. If torsion 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 a sample output of an actual reinforcement pattern developed by STAAD. The following annotations apply:l

LEVEL - Serial number of the bar center which may contain one or more bar groups. HEIGHT - Height of bar level from the soffit of the beam in relation to its local y axis. BAR INFO - Reinforcement bar information specifying number of bars and their size. FROM - Distance from the start of the beam to the start of the reinforcing bar. TO - Distance from the start of the beam to the end of the reinforcing bar. ANCHOR - States whether anchorage, either a hook or (STA,END) continuation, is needed at start (STA) or at the end (END).

l

l

l

l

l

l

The following is an example TRACK 2.0 beam design output:==================================================================== B E A M N O. 13 D E S I G N R E S U L T S - FLEXURE LEN - 1500. mm FY - 460. FC - 30. SIZE - 300. X 300. mm LEVEL HEIGHT BAR INFO FROM TO ANCHOR

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mm mm mm STA END ------------------------------------------------------------------1 29. 4- 8 MM 467. 1500. NO YES 2 264. 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/ 3 125. 0.0/ 157.2 0.00/ 16.80 0/ 3 250. 0.0/ 129.9 0.00/ 13.89 0/ 3 375. 0.0/ 117.0 0.00/ 10.98 0/ 3 500. 0.0/ 117.0 0.00/ 8.07 0/ 3 625. 0.0/ 117.0 0.00/ 5.16 0/ 3 750. 0.0/ 117.0 0.00/ 2.25 0/ 3 875. 117.0/ 0.0 2.15/ 0.00 1/ 0 1000. 117.0/ 0.0 5.25/ 0.00 1/ 0 1125. 117.0/ 0.0 8.36/ 0.00 1/ 0 1250. 117.0/ 0.0 11.46/ 0.00 1/ 0 1375. 136.3/ 0.0 14.57/ 0.00 1/ 0 1500. 165.3/ 0.0 17.67/ 0.00 1/ 0 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 | | | ====================================================|| | | |_____________________________________________________________________ ______| _______________ _______________ _______________ _________ ______ | | | | | | | | B E A M

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British Codes - Concrete Design per BS8110

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2A.6 Column DesignColumns are designed for axial force and biaxial bending at the ends. All active loadings are tested to calculate reinforcement. The loading which produces maximum reinforcement is called the critical load and is displayed. The requirements of BS8110 Part 1 - section 3.8 are followed, with the user having control on the effective length in each direction by using the ELZ and ELY parameters as described in Table 2A.1. Bracing conditions are controlled by using the BRACE parameter. The program will then decide whether or not the column is short or slender and whether it requires additional moment calculations. For biaxial bending, the recommendations of 3.8.4.5 of the code are considered. Column design is done for square, rectangular and circular sections. For rectangular and square sections, the reinforcement is always assumed to be arranged symmetrically. This causes slightly conservative results in certain cases. Below is a typical column design results. Using parameter TRACK 1.0, the detailed output below is obtained. TRACK 0.0 would merely give the bar configuration, required steel area and percentage, column size and critical load case.==================================================================== C O L U M N N O. 1 D E S I G N R E S U L T S FY - 460. FC -30. N/MM2 SQRE SIZE - 300. X 300. MM, AREA OF STEEL REQUIRED = 940. SQ. MM. BAR CONFIGURATION REINF PCT. LOAD LOCATION ---------------------------------------------------12 10 MM 1.047 1 EACH END (PROVIDE EQUAL NUMBER OF BARS AT EACH FACE) ---------------------------------------------------|BRACED /SLENDER in z E.L.z= 4500 mm (3.8.1.3 & 5)|

66 STAAD.Pro

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

2A.7 Slab DesignSlabs are designed to BS8110 specifications. To design a slab, it must first be modeled using finite elements. The command specifications are in accordance with Section 5.52 of the Technical Reference Manual. A typical example of element design output is shown in below. The reinforcement required to resist the Mx moment is denoted as longitudinal reinforcement and the reinforcement required to resist the My moment is denoted as transverse reinforcement ( Fig. 4.1 ). The following parameters are those applicable to slab design:l

FYMAIN - Yield stress for all reinforcing steel FC - Concrete grade CLEAR - Distance from the outer surface to the edge of the bar. This is considered the same on both surfaces. SRA - Parameter which denotes the angle of the required transverse reinforcement relative to the longitudinal reinforcement for the calculation of Wood & Armer design moments.

l

l

l

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

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

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British Codes - Concrete Design per BS8110

the reinforcement bar. The resulting Mx* and My* moments are calculated and shown in the design format. The design of the slab considers a fixed bar size of 16 mm in both directions with the longitudinal 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/metre FY=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) -----------------------------------------------------------------