简支组合梁强度设计（依据澳大利亚标准 AS 2327.1–1996）

Design of Simply-Supported Composite Beams for Strength

(To Australian Standard AS 2327.1–1996)

Design Booklet DB1.1

OneSteel Market Mills

Composite Structures Design Manual

February 2001

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OneSteel Market Mills Composite Structures Design Manual

Published by

OneSteel Manufacturing Limited

ABN 42 004 651 325

Produced by the

Centre for Construction Technology & Research

University of Western Sydney

Contributors

Dr. Mark Patrick *

Centre for Construction Technology & Research

Dr. Daya Dayawansa *

Mr. Rodney Wilkie *

* Formerly BHP Melbourne Research Laboratories

Reviewed by

Prof. Russell Bridge

Centre for Construction Technology & Research

Mr. Mark Sheldon

Connell Wagner

Mr. Ken Watson

Formerly BHP Integrated Steel

Edition 1.0 - May 1998

Edition 2.0 - February 2001

Disclaimer

While every effort has been made and all reasonable care taken to ensure the accuracy of the material contained herein, the contributors, editors and publishers of this booklet shall not be held liable or responsible in any way whatsoever, and expressly disclaim any liability or responsibility for any loss or damage, cost or expenses, howsoever incurred by any person whether the user of the booklet or otherwise including without limitation, loss or damage, costs or expenses incurred as a result of or in connection with the reliance, whether whole or partial by any person as a foresaid upon any part of the contents of this booklet. Should expert assistance be required, the services of a competent person should be sought.

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Foreword

OneSteel is a leading manufacturer of steel long products in Australia after its spin-off from BHP Pty Ltd on the 1st November 2000. It manufactures a wide range of steel products, including structural, rail, rod, bar, wire, pipe and tube products and markets welded beams.

OneSteel is committed to providing to design engineers, technical information and design tools to assist with the use, design and specification of its products. This design booklet “Design of Simply-Supported Composite Beams for Strength” was one of the first two design booklets of the Composite Structures Design Manual, which is now being completed and maintained by OneSteel.

The initial development work required to produce the design booklets was carried out at BHP Melbourne Research Laboratories before its closure in May 1998. OneSteel Market Mills is funding the University of Western Sydney’s Centre for Construction Technology and Research in continuing the research and development work to publish this and future booklets.

The Composite Structures Design Manual refers specifically to the range of long products that are manufactured by OneSteel and plate products that continue to be manufactured by BHP. It is strongly recommended that OneSteel sections and reinforcement and BHP plate products are specified for construction when any of the design models in the design booklets are used, as the models and design formulae including product tolerances, mechanical properties and chemical composition have been validated by detailed structural testing using only OneSteel and BHP products.

To ensure that the Designer’s intent is met, it is recommended that a note to this effect be included in the design documentation.

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Contents

Preface iv

1. Scope and General

1.1 Scope 1

1.2 General 1

2. Terminology

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3. Design Concepts

3.1 Shear Connection 7

3.2 Beam Bending 8

3.3 Design Vertical Shear Capacity (φV_U) 13

3.4 Moment-Shear Interaction 14

3.5 Design Moment Capacity (φM_bv) as a Function of β and γ 14

3.6 Effect of Propping on Design Moment Capacity 15

4. Design Models

4.1 Representation of a Composite Beam at the Strength Limit State 17

4.2 Ductile Shear Connection Model 18

4.3 Moment-Shear Interaction Model 18

5. Design Approach

5.1 Design Objectives 20

5.2 Limit State Requirements 20

5.3 Design Procedure Flowchart 20

5.4 Representation of Composite Beam and Loading 20

5.5 Potentially Critical Cross-sections (PCC's) 22

5.6 Effective Sections of a Composite Beam 22

5.7 Design Action Effects at PCC's 23

5.8 Design Moment Capacity (φM_bv) versus Degree of Shear Connection (β) Relationship and Minimum Degree of Shear Connection (β_i) at a PCC 24

5.9 Compressive Force in Concrete (F_cp,i) at a PCC 26

6. Design Rules

6.1 General 27

6.2 Design Objectives 27

7. Worked Examples

7.1 General 28

7.2 Identification of Potentially Critical Cross-Sections 28

7.3 Calculation of Effective Section 30

7.4 Calculation of Design Action Effects 35

7.5 Calculation of Vertical Shear Capacity (φV_U) 37

7.6 Calculation of Design Moment Capacity (φM_b) versus Degree of Shear Connection (β) Relationship 37

7.7 Calculation of Minimum Degree of Shear Connection (β_i) at PCC's 39

7.8 Calculation of Concrete Compressive Force (F_cp,i) Corresponding to Minimum Degree of Shear Connection (β_i) 41

8. References

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Appendices

A. Design Tables 44

B. Notation 46

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Preface

This design booklet forms part of a suite of booklets covering the design of simply-supported and continuous composite beams, composite slabs, composite columns, steel and composite connections and related topics. The booklets are part of the OneSteel Market Mills' Composite Structures Design Manual which has been produced to foster composite steel-frame building construction in Australia to ensure cost-competitive building solutions for specifiers, builders and developers.

Simply-supported composite beams have been favoured in the construction of composite steel-frame buildings in Australia. This is essentially because simple steel connections such as the web-side-plate connection (see design booklet DB5.1 – Design of the Web-Side-Plate Steel Connection) are very economical to use when the steel frame is erected.

This design booklet contains important explanatory information and worked examples about the strength design method in Section 6 of Australian Standard AS 2327.1-1996, Composite Structures, Part 1: Simply Supported Beams. It is intended that this information will assist structural design engineers to understand the engineering principles on which the design method is based. The coverage of the strength design method is continued in design booklet DB1.2 – Design of the Shear Connection of Simply-Supported Composite Beams (To Australian Standard AS 2327.1-1996).

Design aids have already been prepared to support the use of the design method, and are included in the Composite Beam Design Handbook (in Accordance with AS 2327.1-1996) [2] published jointly by the AISC and Standards Australia. These comprise Design Tables (Appendix A) and computer software (COMPBEEAM™). Although these design aids are intended to make the design process more efficient, it is essential that the users have a clear understanding of the design concepts and design rules prior to using them.

The strength design method in AS 2327.1 is based on partial shear connection strength theory and rectangular stress block theory, and is applicable to the design of composite beams with compact steel sections and ductile shear connection. Non-compact steel sections can be catered for by representing them in design as equivalent compact sections. Slender steel sections are not permitted. Details for ensuring that ductile shear connection is achieved are given in Sections 8 and 9 of AS 2327.1, and explanatory information about these rules can be found in design booklet DB1.2. Computer program COMPSHEAR™ can be used in association with COMPBEAM™ to design the shear connection in accordance with DB1.2.

The method of strength design presented for simply-supported composite beams has also been extended to cover the design of continuous composite beams, noting that very similar principles apply. The reader is referred to design booklet DB2.1 – Design of Continuous and Semi-Continuous Composite Beams with Rigid Connections for Strength, and an associated computer program COMPSECT™. Partial shear connection strength theory is also applicable to the design of composite slabs with ductile shear connection, which is also covered in a separate design booklet DB3.1 – Design of Composite Slabs for Strength. Finally, it is important to point out that the strength design method in AS 2327.1 is in harmony with leading overseas Codes, Standards and Design Specifications which address the design of composite beams.

Edition 1.0 was published by BHP in May 1998. Edition 2.0 contains some minor corrections to the first edition, and is published by OneSteel.

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