Earthquake-Resistant Design of Structures, Second Edition [Shashikant K. Duggal] PDF

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Earthquake‐Resistant  Design of Structures  Second Edition          Shashikant K. Duggal                          OXFORD  UNIVERSITY PRESS      © Oxford University Press 2013  ISBN: 978-0-19-808352-8 Preface to the First Edition vii The scope of this book is restricted to the field of earthquake-res...

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Earthquake-Resistant Design of Structures, Second Edition [Shashikant K. Duggal]

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Earthquake‐Resistant  Design of Structures  Second Edition          Shashikant K. Duggal                         

OXFORD  UNIVERSITY PRESS   

 

© Oxford University Press 2013  ISBN: 978-0-19-808352-8

Preface to the First Edition vii

The scope of this book is restricted to the field of earthquake-resistant design and books on earthquakes and structural dynamics must be referred in order to gain a well-balanced view of the entire field. All suggestions and feedback for further improvement of the text can be sent to [email protected]. S.K. Duggal

Preface to the First Edition Earthquakes are perhaps the most unpredictable and devastating of all natural disasters. They not only cause great destruction in terms of human casualties but also have a tremendous economic impact on the affected area. The concern about seismic hazards has led to an increasing awareness and demand for structures designed to withstand seismic forces. In such a scenario, the onus of making the buildings and structures safe in earthquake-prone areas, lies on the designers, architects, and engineers who conceptualize these structures. Codes and recommendations, postulated by the relevant authorities, study of the behaviour of structures in past earthquakes, and understanding the physics of earthquakes are some of the factors that help in the designing of an earthquake-resistant structure.

About the Book This book introduces and explains all aspects of earthquake-resistant design of structures. Designed as a textbook for undergraduate and graduate students of civil engineering, practising engineers and architects will also find the book equally useful. It has been assumed that the reader is well acquainted with structural analysis, structural dynamics, and structural design. The design of earthquake-resistant structures is an art as well as science. It is necessary to have an understanding of the manner in which a structure absorbs the energy transmitted to it during an earthquake. The book provides a comprehensive coverage of the basic principles of earthquake-resistant design with special emphasis on the design of masonry, reinforced concrete, and steel buildings. The text is focussed on the design of structural and non-structural elements in accordance with the BIS codes (456, 800, 875, 1893, 1905, 4326, 13828, 13920, and 13935). This book contains 11 chapters, which comprehensively discusses the design of earthquake-resistant structures. Starting with the elements of earthquake theory and seismic design, dynamics of structures and soils and their seismic response,

viii

Preface to the First Edition

the book goes on to elucidate the conceptualization and actualization of the design of earthquake-resistant structures. Detailed seismic analyses of different types of buildings, such as masonry, timber, reinforced concrete, and steel buildings, follow. Finally, a comprehensive discussion of the behaviour of non-structural elements under seismic forces and an analysis of the 2001 Bhuj earthquake are presented as concluding chapters. Suitable figures and diagrams have been provided to ensure an easy understanding of the concepts involved. The chapters are divided into small sections that are independent in themselves. A large number of solved problems, which encompass the topics introduced in the chapter, have been integrated at the end of relevant chapters. A summary of the salient features of each chapter has also been consolidated into the body of the chapter. Another unique feature of the book is the grey screens interspersed throughout the text, which highlight important design norms and considerations. Bibliographic references, both empirical and theoretical, are listed at the end of the book for those interested in further reading. A list of websites that have been referred to is also provided therein. A case study of the 2001 Bhuj earthquake has been included as the final chapter of the book. A special attempt has been made to cover all relevant topics of the discipline and make the book a self-contained course in earthquake-resistant design of structures.

Acknowledgements I extend my sincere thanks to Prof. C.V.R. Murthy of IIT Kanpur for his valuable suggestions for the preparation and organization of the text. I am grateful to Prof. Sudhir K. Jain of IIT Kanpur for his support. I am also thankful to the Earthquake Engineering Research Institute at Oakland, California, for their permission to use the photographs of damage caused by the Bhuj 2001 earthquake. I acknowledge my colleagues Prof. K.K. Shukla, Dr. P.K. Mehta, K. Venkatesh, and G. Ghosh for their support and suggestions. I am also thankful to Shubhendu Singh, P. Mohan Rao, Meenakshi Dewangan, and S. Chakravarthi G. for their assistance in the typing of the manuscript and the preparation of the figures. All suggestions and feedback for further improvement of the text are welcome. S.K. Duggal

Preface to the Second Edition The main objective of a course on earthquake-resistant design of structures is to introduce students to the phenomenon of earthquakes and the process, measurements, and factors that affect the design of structures in seismic areas. This objective is achieved by understanding the fundamentals of the theory of vibrations necessary to comprehend and analyse the mutual dynamics of earthquakes and structures. The student is also familiarized with the codal provisions as well as aseismic design methodology. According to Earthquakes Today, around 500,000 earthquakes occur each year; 100,000 of these can actually be felt. The magnitude and destructive consequences of earthquakes have serious implications. The destruction and damage of constructed and natural environment and the loss and impairment of human life are of prime concern. A notable feature of the disaster caused by earthquakes is that harm to life is associated almost entirely with man-made structures, e.g., collapse of buildings, bridges, dams. During an earthquake, when the ground shakes at a building site, the building’s foundations vibrate in a manner that is similar to the surrounding ground. To overcome this effect, research has spawned numerous innovations now common in earthquake engineering, including ductile detailing of concrete structures, improved connections for moment frames, base-isolation technology, energydissipation technology, and computing tools. Current research activities are focused on three areas: performance-based design, development of damageresistant systems, and improvement in the ability to predict the occurrence and intensity of earthquakes.

About the Book Our knowledge about earthquakes has advanced enormously during the past couple of decades. Corresponding advances have also been made in our understanding of the behaviour of structures, and consequently new and stringent specifications have been introduced and enforced. In this second edition, the dynamics of structures is dealt with in detail to give the book completeness. Further, with the revision of the code IS 800 in 2007, the design philosophy recommended is limit state design. Consequently, the treatment of steel structures in Chapter 9 has been overhauled completely, focusing on the new code IS 800: 2007.

iv

Preface to the Second Edition

While working on the second edition, the goal has been to retain the organization of the book and to develop and update the topics more carefully and logically. The text has been reviewed closely and objectively modified. An attempt has been made to provide a simple, balanced, and exhaustive coverage of the information needed for the design of earthquake-resistant structures. The first edition of the book was prepared with an understanding that students undertaking a course on earthquake-resistant design of structures must already have the basic knowledge of dynamics of structures. However, feedback and suggestions from students, faculty, and reviewers suggest that the book must cover dynamics of structures in greater detail. Although textbooks are available on structural dynamics as well as earthquake-resistant design of structures, this book is an effort to cover a range of structures in a balanced way, which was lacking in other books. Numerous solved examples have been added to assist the reader in developing a full understanding of the application of the theory involved. Moreover, each of these examples has been carefully chosen to supplement and extend the ideas and concepts given in the text.

New to the Second Edition • Comprehensive and thoroughly revised text • Completely revised chapters on dynamics of structures and seismic response and steel buildings • New illustrations, problems, and review questions • New sections including the Indian plate and Himalayan earthquakes, response spectrum, hybrid seismic control systems, confined masonry construction, and lateral load transfer in timber buildings • Two new appendices—Determination of natural frequencies and mode shapes, and Bauschinger effect

Key Features • Elucidates the theoretical as well as practical aspects of earthquake-resistant designs • Includes a case study on the 2001 Bhuj earthquake as an insight into the effects of seismic forces on structures • Provides standard tables both in the text and in the appendices for ready reference • Incorporates pedagogical features such as solved problems, review questions, chapter-end exercises, and highlighted information on design specifications and norms

Extended Chapter Material Chapter 1 has been expanded. It now introduces the movements of the Indian plate and the Himalayan earthquakes. The graphical method to locate an earthquake and

Preface to the Second Edition v

the method used to determine the annual frequency of earthquakes are described. The chapter classifies earthquakes, expands the two measures of earthquakes, and includes the MSK-64 intensity scale. The section on magnitude has been expanded and rewritten. The influence of local site conditions on the dynamic characteristics of ground motion—local site effects—is presented in detail. Chapter 2 has been completely rewritten. The methods of solving the differential equation of motion have been introduced and their suitability for linear and nonlinear systems discussed. SI units have been introduced and followed as far as possible. A simple method to estimate damping has been introduced. Response to forced vibrations including harmonic vibration and general loading is described. Chapter 3 includes soil models, methods of analysis of soil-structure interaction, and testing of soil characteristics. Chapter 5 has been expanded, including detailed discussions on seismic response control and systems. Passive, active, hybrid, and semi-active control systems are described along with their strategic application in structures. The relative merits, demerits, and limitations of each of these systems are highlighted. Chapter 6 now discusses confined masonry construction. Chapter 7 elaborates upon lateral load transfer in timber buildings, floors and roofs, and ductile behaviour of joints. Chapter 9 is completely rewritten, as the code of practice, IS 800: 2007, for steel structures has been revised and recommends the use of limit state design. It also contains provisions and specifications for seismic design of steel structures. Although this is an elementary treatment, the reader will find the text quite rigorous and comprehensive. Two new appendices—Determination of natural frequencies and mode shapes and Bauschinger effect—have been added to support the text.

Content and Structure Chapter l begins with an introduction to the earthquake phenomenon, including the causes, occurrence, and properties of earthquakes. It then goes on to explain the characteristics of seismic waves, the effect they have on structures, and how seismic design theory attempts to combat the effects of seismic forces on buildings and structures. Chapter 2 deals with the dynamics of structures and their seismic response. The concepts of mechanics involved in the design of structures and in modelling a structure for the study of seismic forces are the highlights of this chapter. Chapter 3 elucidates the behaviour of soils and soil elements and the analysis of soil–structure systems. Soil modes and testing of soil characteristics are also integrated in this chapter. Chapter 4 elaborates upon the scientific and economical arrangement of structural members to support the anticipated seismic forces, the lateral load transfer mechanism, the effects of asymmetry, and irregularities in plan and elevation and their effects.

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Preface to the Second Edition

Chapter 5 discusses the analysis and design of common structures in general. The two methods of analysis—the equivalent lateral force method and the response spectrum method—are described in detail. Chapter 6 discusses the behaviour of unreinforced and reinforced masonry walls. The chapter also provides an insight into the behaviour of infill walls, load combinations, and permissible stresses. The methods for seismic design of walls and bands and improvement of seismic behaviour of masonry buildings are also elucidated. Chapter 7 discusses the seismic behaviour and design of timber buildings. It includes detailed discussions on structural form, site response, fire resistance, and decay of timber buildings. The construction methods described in this chapter include brick-nogged timber frame construction, timber shear panel construction, and restoration and strengthening of timber buildings. Chapter 8 describes the behaviour of reinforced cement concrete buildings under seismic forces and details the seismic design requirements for RC buildings. The topics covered in this chapter include behaviour of structural elements, joints, and shear walls; seismic design of structural elements; pre-stressed and pre-cast concrete; and retrofitting and strengthening of RC buildings. Chapter 9 deals with steel buildings and covers important details of steel construction in seismically active areas. The chapter opens with an introduction to the behaviour of steel and steel frames and goes on to discuss frame members and flexural members, connection design and joint behaviour, and steel panel zones and bracing members. Chapter 10 provides information on non-structural elements, including topics such as failure mechanisms of non-structures, dynamic and static analyses of non-structures, and methods for prevention of damage to non-structures. Chapter 11 is a case study of the Bhuj 2001 earthquake. It includes a list of earthquake parameters and geological effects and analyses the behaviour of different types of buildings in the most-affected zones. The case study is supplemented with images from the affected area. The 11 appendices at the end of the book provide additional information to support the text.

Acknowledgements I am deeply grateful to my colleague, Dr Rama Shankar, who has provided all tangible and intangible assistance in the preparation of this edition of the book. I am thankful to Prof. K.K. Shukla, Prof. A.K. Sachan, Prof. R.K. Srivastava, and Dr Kumar Pallav, Scientific Officer, IIT Guwahati, for their invaluable support and technical suggestions as and when needed. Thanks are due to my Ph D scholar Mr S.T. Rushad, postgraduate student Mr Jemy, and undergraduate students who worked hard to help in logically checking the text and solved examples and exercises.

Preface to the First Edition vii

The scope of this book is restricted to the field of earthquake-resistant design and books on earthquakes and structural dynamics must be referred in order to gain a well-balanced view of the entire field. All suggestions and feedback for further improvement of the text can be sent to [email protected]. S.K. Duggal

Preface to the First Edition Earthquakes are perhaps the most unpredictable and devastating of all natural disasters. They not only cause great destruction in terms of human casualties but also have a tremendous economic impact on the affected area. The concern about seismic hazards has led to an increasing awareness and demand for structures designed to withstand seismic forces. In such a scenario, the onus of making the buildings and structures safe in earthquake-prone areas, lies on the designers, architects, and engineers who conceptualize these structures. Codes and recommendations, postulated by the relevant authorities, study of the behaviour of structures in past earthquakes, and understanding the physics of earthquakes are some of the factors that help in the designing of an earthquake-resistant structure.

About the Book This book introduces and explains all aspects of earthquake-resistant design of structures. Designed as a textbook for undergraduate and graduate students of civil engineering, practising engineers and architects will also find the book equally useful. It has been assumed that the reader is well acquainted with structural analysis, structural dynamics, and structural design. The design of earthquake-resistant structures is an art as well as science. It is necessary to have an understanding of the manner in which a structure absorbs the energy transmitted to it during an earthquake. The book provides a comprehensive coverage of the basic principles of earthquake-resistant design with special emphasis on the design of masonry, reinforced concrete, and steel buildings. The text is focussed on the design of structural and non-structural elements in accordance with the BIS codes (456, 800, 875, 1893, 1905, 4326, 13828, 13920, and 13935). This book contains 11 chapters, which comprehensively discusses the design of earthquake-resistant structures. Starting with the elements of earthquake theory and seismic design, dynamics of structures and soils and their seismic response,

Brief Contents Preface to the Second Edition

iii

Preface to the First Edition

vii

Detailed Contents

x

1. Earthquakes and Ground Motion

1

2. Dynamics of Structures and Seismic Response

43

3. Dynamics of Soils and Seismic Response

118

4. Conceptual Design

149

5. Code-based Analysis Method and Design Approaches

176

6. Masonry Buildings

247

7. Timber Buildings

298

8. Reinforced Concrete Buildings

330

9. Steel Buildings

402

10. Non-structural Elements

449

11. Bhuj Earthquake 2001: A Case Study

470

Appendices I. Seismic Zones in India 483 II. Some Significant Earthquakes in India 484 III. Zone Factor for Some Important Towns in India 484 IV. Definitions of Irregular Buildings—Plan Irregularities 486 V. Definitions of Irregular Buildings—Vertical Irregularities 487 VI. Determination of Natural Frequencies and Mode Shapes 488 VII. Horizontal Seismic Coefficient (o) 489 VIII. Importance Factor (I) 489 IX. Soil-foundation Factor () 490 X. Second-order Effects (P- Effects) 490 XI. Bauschinger Effect 492

483

Bibliography

493

Index

506

Detailed Contents Preface to the Second Edition

iii

Preface to the First Edition

vii

Brief Contents

ix

1. Earthquakes and Ground Motion 1.1 1.2

1.3 1.4 1.5 1.6 1.7 1.8...