second edition limit state design in structural steel€¦ · · 2017-03-03the need for a book on...

M.R. Shiyekar

STRUCTURALSTEELRevised as perAmendment No.1to IS800:2007

Limit State Design in

Second Edition

Limit State Design inStructural Steel

M.R. SHIYEKARFormer Principal

andProfessor in Structural Engineering

Pune

Delhi-1100922013

SECOND EDITIONRevised as per Amendment No. 1 to IS 800: 2007

LIMIT STATE DESIGN IN STRUCTURAL STEEL, Second EditionM.R. Shiyekar

© 2013 by PHI Learning Private Limited, Delhi. All rights reserved. No part of this book may bereproduced in any form, by mimeograph or any other means, without permission in writing fromthe publisher.

ISBN-978-81-203-4784-7

The export rights of this book are vested solely with the publisher.

Third Printing (Second Edition) ººººº ººººº May, 2013

Published by Asoke K. Ghosh, PHI Learning Private Limited, Rimjhim House, 111, PatparganjIndustrial Estate, Delhi-110092 and Printed by Baba Barkha Nath Printers, Bahadurgarh,Haryana-124507.

Tothe Profound Memory of

my Parentsthe Late Ramchandra and the Late Susheela

Preface ix

Preface to the First Edition xi

Acknowledgements xiii

1. Introduction 1–31.1 What is Structural Design? 2

2. Philosophy of Limit State Design 4–182.1 Introduction 42.2 Types of Structural Steel 42.3 Stress–Strain Curve for Mild Steel under Uniaxial Tension 52.4 Why Limit State Design? 72.5 Philosophy of Design 8

2.5.1 Limit State of Strength 82.5.2 Limit State of Serviceability 92.5.3 Classification of Sections 92.5.4 Classification of Cross-sections—Codal Provisions 10

Exercises 17

3. Tension Members 19–413.1 Introduction 193.2 Limit Strength of Tension Member 20

3.2.1 Design Strength due to Yielding of Gross Section 203.2.2 Design Strength due to Rupture at Critical Section 203.2.3 Angle Sections 213.2.4 Design Strength due to Block Shear 22

3.3 Threaded Rods 36

Exercises 39

4. Compression Members 42–734.1 Introduction 424.2 Buckling Classification 43

Contents

v

vi Contents

4.3 Codal Provisions 464.4 Effective Length of Compression Member 484.5 Laced/Battened Column 594.6 Lacing System 614.7 Battening System 66

Exercises 73

5. Plastic Analysis 74–1105.1 Introduction 745.2 Historical Research 745.3 Yield Spread in Section 755.4 Shape Factor of Cross-sections 825.5 Determination of Collapse Load 875.6 Complete, Partial and Overcomplete Collapse 101

Exercises 110

6. Flexural Members—Laterally Supported 111–1456.1 Introduction 1116.2 Lateral Restraints 1116.3 Unsymmetrical Bending 1136.4 Gradual Collapse of Beam 1146.5 Huber–Von Mises–Hencky Yield Criterion 1156.6 Codal Provisions 116

Exercises 144

7. Flexural Members—Laterally Unsupported 146–1707.1 Introduction 1467.2 Design of Doubly Symmetric Cross-Section 1477.3 Effectiveness of Bracing/Cross Member 1497.4 Lateral Bracing Member Design 1517.5 Limiting Effective Length of Compression Flange 1537.6 Design of Laterally Unsupported Beam: Monosymmetric Cross-sections 1537.7 Design of Gantry Girder 157

Exercises 170

8. Beam-Column 171–1908.1 Introduction 1718.2 Combination of Bending (M) with Axial Compression (P) 1718.3 Codal Provisions for Design of Beam-Column 174

8.3.1 Section Strength 1748.3.2 Overall Member Strength 175

Exercises 188

9. Plate Girder 191–2099.1 Introduction 1919.2 Elements of Plate Girder 191

Contents vii

9.3 Plate Buckling 1929.4 Web Buckling in Shear 1929.5 Simple Post-Critical Method 1939.6 Tension Field Action 1949.7 Flange Anchoring Mechanism 1959.8 Actual Failure of Web Panel 1959.9 Codal Provisions 196

9.9.1 Selection of Web 1969.9.2 Depth to Thickness Ratio of Web 1969.9.3 Design of Flange 1979.9.4 Salient Codal Provisions 198

Exercises 209

10. Column Bases 210–22910.1 Introduction 21010.2 Types of Column Bases 21110.3 Codal Provisions (Clause 7.4, p. 46) 212

Exercises 228

11. Portal Frames 230–28811.1 Introduction 23011.2 Plastic Analysis of Rectangular Portal Frames 230

11.2.1 Beam Mechanism 23111.2.2 Sway Mechanism 23111.2.3 Combined Mechanism 232

11.3 Plastic Analysis of Gable Portal Frames 25111.3.1 Analysis 252

11.4 Limit State Design of Portal Frames 26511.5 Rigid Frame Knees 277

11.5.1 Simple and Stiffened Corner Connection 27911.5.2 Tapered Haunches 28211.5.3 Curved Haunch 284

Exercises 285

12. Industrial Structures 289–34012.1 Introduction 28912.2 Design of Truss 291

12.2.1 Design of Purlin 29112.2.2 Codal Provisions 292

12.3 Knee Braced Truss 30712.3.1 Analysis of Knee Braced Roof Truss 311

12.4 Gable Portal Frame 32212.5 Design of Gantry Girder Column 327Exercises 339

viii Contents

13. Foot Bridge 341–36513.1 Introduction 34113.2 Analysis 34113.3 Design 342

Exercises 365

14. Pre-Engineered Buildings 366–38414.1 Introduction 366

Exercises 384

Appendix A 385–397

Appendix B 398–399

Bibliography 401–402

Index 403–405

I appreciate overwhelming response shown by structural consultants, academicians and studentsto the first edition of the book.

This second edition has incorporated all the revisions necessitated due to issue of AmendmentNo. 1 to IS 800: 2007 as promulgated by the Bureau of Indian Standards, Delhi in January 2012.

The attention of the readers is invited to Appendix B of this book where some corrections toIS 800: 2007 were suggested by the author during the course of preparation of the manuscript.Hence some of the amendments to IS 800: 2007 now promulgated by BIS in January 2012 hadalready been taken care of in the first edition of the book in 2010 and its subsequent reprint inApril 2011.

I am thankful to the BIS authorities for taking note of my suggestions for corrections toIS 800: 2007 as listed in Appendix B of the book. Amendments No. 1 of Jan. 2012 contains twomajor changes which affect design calculations.

(a) Upper limit of ‘b’ to obtain Idn of tension member; Clause 6.3.3 of IS 800: 2007 refers.

(b) Revised value of ‘f’ to obtain shear resistance in tension field action; Clause 8.4.2.2 ofIS 800: 2007 refers.

As the second edition has now incorporated all the revisions in the book after the issue ofAmendment No. 1 to IS 800: 2007, I hope the book will now be more useful for structuralconsultants, teachers and students.

I am thankful to Mr. Manas M. Ghosh for helping me in this context.

M.R. Shiyekar

Preface

ix

Many books have been written by eminent authors on the design of steel structures. Most of thebooks available today are based on the working stress method. After the release of IS 800: 2007,the need for a book on the design of steel structures using the limit state design concept was feltstrongly. The draft for this code was available from 2000 onwards. Its early release was expected,and in anticipation of this a few organizations and consulting firms invited me to highlight thecodal provisions of IS 800: 2007. Among them, the major ones are the Institution of Engineers(India), Pune; Indian Society of Structural Engineers (Pune); Epicons Consultants (Mumbai);Aker Solutions (Pune); Technoesis, and S.P. College of Engineering, Andheri (Mumbai); andSardar Vallabhbhai National Institute of Technology (Surat). Also, the Civil Engineering Departmentof Sinhgad College of Engineering, Pune, organized two national workshops on this code—onebefore release (November 2005) and the other after release (July 2009). During all theseprogrammes, I got opportunities to meet and discuss the matter extensively with professionalstructural designers, academicians as well as students. I realized that the reception of new codalprovisions was not very warm, the main reason being the complicated expressions without dueemphasis on the important parts. No special note was provided to explain the logic of the clausesto enable their understanding by the beginners. Very few consultants were aware of the LRFDconcept of AISC specifications. Another gap area was about the understanding of plastic analysis.Many professionals and academicians requested me to make a contribution towards filling thesegaps; hence this publication.

I got inspiration from all those who interacted with me during the training programmes andalso from all my undergraduate and postgraduate students, who desired that I undertake thisHerculean task of writing this book. I hope I have been able to do justice to this cause. I have takenefforts to explore some fundamental principles of this vast subject. I have not emphasized importanttopics such as types of steel and their properties, types of bolts and dimensional details, bracingsystems in buildings, and earthquake considerations. The topics such as plastic analysis of structuresare, however, extensively illustrated. The properties of rolled steel sections, often required inclauses and not appearing in the present steel section tables, are given in Appendix A. Comparisonbetween Working Stress Method and Limit State Method is done for many applications.

It is essential for a structural steel designer to understand the process of transfer of action fromone element to other precisely. Connection design requires this even more. Structural steel design

Preface to the First Edition

xi

requires clear concepts in structural analysis and strength of materials. Structural steel detailing isequally important for a precise fabrication process. Detailing to millimetre dimensions is requiredin structural steel drafting. Edge distances, end distances, pitch, cleat dimensions, weld lengthsand gusset plate profiles need to be precisely decided. The connection details at the end of membersaffect the end-condition of the member and its effective length, which in turn affect the structuraldesign. Hence the condition assumed in analysis needs to be precisely incorporated in design.

I hope the readers of this book will find it useful while applying the design principles based onthe new IS 800: 2007. I will be obliged if they convey their opinions and suggestions for theimprovement of the contents of the book, and point out any necessary corrections in it, bye-mailing me at [email protected].

Acknowledgements

I am indebted to Dr. P.N. Gore and the late Prof. M.D. Bhate, my teachers at Walchand College ofEngineering, Sangli (Maharashtra), for arousing intensive interest in my mind in plastic analysisand design of steel structures.

I sincerely thank Prof. M.N. Navale, Founder President of Sinhgad Technical Education Society,Pune, for giving me an opportunity to work in Sinhgad College of Engineering even after attainingthe age of retirement and also the encouragement given to me to write this book.

With a deep sense of gratitude, I express my thanks to Mrs. Sagarika Ghosh, Director,PHI Learning, New Delhi, for her consent to my proposal to publish this book. I wholeheartedlythank Mr. Darshan Kumar, Senior Editor, PHI Learning, who helped me at every stage of thispublication. I express my sincere thanks to Mr. S.G. Joshi, Executive Engineer, IrrigationDepartment, Pune, who corresponded regularly with PHI Learning on important matters related tothis book.

I am thankful to Mr. Manas M. Ghosh, Manager, INSDAG, Kolkata for helping me to conductat my college national workshops on revised codal provisions.

My wife Suchitra deserves special appreciation for providing moral support to me during allstages of this publication. My family members—Sandeep, Seema, Swati and Atul—acted literallyas four pillars while building this book. My granddaughter, Miss Tanvi, and grandson, MasterAtharva, helped me to de-stress myself during particularly hectic periods.

My postgraduate students Rahul Mali, Mangesh More, Anay Karambelkar, Amrita Chopdeand undergraduate students Savan Shah, Mugdha Rasal, Mugdha Ramdasi, Sagar Vispute andNikhil Yokar made valuable contributions to this book. I am rather thankful to them.

I thank the Principal of Sinhgad College of Engineering, Pune, and all my colleagues of CivilEngineering Department, for their encouragement.

I take this opportunity to express my heartfelt thanks to Mr. A.K. Kagalkar for screening themanuscript carefully and suggesting important corrections. I also thank Dr. C.E. Deshpande andDr. V.L. Shah for helping me to prepare the manuscript in a proper form.

I am very much grateful to the authorities of Tata Bluescope Steel for providing and grantingpermission to reproduce tables and figures in the chapter on pre-engineered buildings (PEB). I amalso thankful to Zamil Steel Buildings India for according permission to use details regardingPEB.

M.R. Shiyekar

xii Preface to the First Edition

Acknowledgements

xiii

The following extracts, figures and tables from IS 800: 2007 have been reproduced in this publicationwith the permission of the Bureau of Indian Standards, Manak Bhawan, New Delhi. I thank theBureau of Indian Standards for granting permission to reproduce some clauses, tables and figuresfrom the IS 800: 2007 revised code of practice to enable reference by the readers of this book.

Particulars Page No.

Section 2.5.4 11

Table 2.1 12

Figure 2.3 13

Figure 3.4 22

Figure 4.6 46

Figure 4.7 47–48

Reference is invited to IS 800: 2007 for further details.It is desirable that for more complete details, reference be made only to the latest version of

this standard, which is available from the Bureau of Indian Standards, Manak Bhawan, New Delhi.

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Limit State Design In Structural Steel

Publisher : PHI Learning ISBN : 9788120347847 Author : M R Shiyekar

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