SEISMIC DESIGN OF REINFORCED CONCRETE AND MASONRY BUILDINGS A WILEY INTERSCIENCE PUBLICATION PDF

Preview

Summary

SEISMIC DESIGN OF REINFORCED CONCRETE AND MASONRY BUILDINGS T. Paulay Department of Civil Engineering University of Canterbury Christchurch New Zealand M. J. N. Priestley Department of Applied Mechanics and Engineering Sciences University of California Sun Diego, USA A WILEYINTERSCIENCE PUBLICATION ...

Description

Accelerat ing t he world's research.

SEISMIC DESIGN OF REINFORCED CONCRETE AND MASONRY BUILDINGS A WILEY INTERSCIENCE PUBLICATION armi mida

Related papers

Download a PDF Pack of t he best relat ed papers 

Masonry wall frame design and performance Enio Deneko Wind and Eart hquake Resist ant Buildings (ref. ASCE 7 02, AISC 341 02, ACI 318 02, 2003 IBM) (MD 2005) albert o ramos SEAOC SSDM VOL Jean Luck Pineda

SEISMIC DESIGN OF REINFORCED CONCRETE AND MASONRY BUILDINGS

T. Paulay Department of Civil Engineering University of Canterbury Christchurch New Zealand

M. J. N. Priestley Department of Applied Mechanics and Engineering Sciences University of California Sun Diego, USA

A WILEYINTERSCIENCE PUBLICATION JOHN WILEY & SONS, INC. New York

Chichester

Brisbanc

Toronto

Singapore

Portions of Chapters 4, 5, 6, 8, and 9 were originally published in the German language in "Erdbebenbemessung von Stahlbetonhochbauten," by Thomas Paulay, Hugo Bachmann, and Konrad Maser. 0 1990 Birkhaeuser Verlag Basel." In recognition of the importance of preserving what has been written, it is a policy of John Wiley & Sons, Inc., to have books of enduring value published in the United States printed on acid-free paper, and we exert our best efforts to that end. Copyright O 1992 by John Wiley & Sons, Inc. All rights reserved. Published simultaneously in Canada. Reproduction or translation of any part of this work beyond that permitted by Section 107 o r 108 of the 1976 United States Copyright Act without the permission of the copyright owner is unlawful. Requests for permission or further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. Libmty of Congress Cataloging in Publication Data:

Paulay, T., 1923Seismic design of reinforced concrete and masonry buildings/T, Paulay, M. J. N. Priestley. p. crn. Includes bibliographical references and index. ISBN 0-471-54915-0 1. Earthquake resistant design. 2. Reinforced concrete construction. 3. Buildings, Reiniorced concrete-Earthquake emects. 4. Masonry 1. Priestley, M. J. N. 11. Title.

91-34862 CIP Printed in the United States of America 1098765432

PREFACE Involvement over many ycars in the teaching of structural engineering, the design of structures, and extensive research relevant to reinforced concrete and masonry buildings motivated the preparation of this book. Because of significant seismic activity in New Zealand and California, our interest has naturally focused primarily o n the response of structures during scvcre earthquakes. A continuing dialogue with practicing structural designers has facilitated the translation of research findings into relatively simple design recommendations, many of which have bccn in usc in New Zcaland for a number of years. We address ourselves not only to structural enginecrs in seismic regions but also to students who, having completed an introductory course of reinforced concrete theory, would like to gain an understanding of seismic design principles and practice. Emphasis is on design rather than analysis, since considerable uncertainty associated with describing expected ground motion characteristics make detailed and sophisticated analyses of doubtful value, and indicate the scope and promise in "telling" the structure how it must respond under potentially wide range of earthquake characteristics, by application of judicious design principles. The three introductory chapters present basic concepts of seismic design, review the causes and effects of earthquakes and current procedures to quantify seismicity, structural response, and seismic actions to be considered in design, and summarize established principles of reinforced concrete and masonry member design. The remaining six chapters cover in considerable detail the design of typical building structures, such as reinforccd concrcte ductile frames, structural walls, dual systems, reinforced masonry structures, buildings with restricted ductility, and foundation systems. Because with few exceptions seismic structural systems must posscss significant ductility capacity, the importance of establishing a rational hierarchy in the formation of uniquely defined and admissible plastic mechanisms is emphasized. A deterministic capacity design philosophy embodics this feature and it serves as a unifying guide throughout the book. Numerous examples, some quite detailed and extensive, illustrate applications, including recommended detailing of the reinforcement, to ensure the attainment of intended levels of ductility where required. Design approaches are based on first principles and rationale without adherence to building codes. However, references are made to common codified approaches, particularly those in

vi

PREFACE

the United States and New Zealand, which arc very similar. Observed structural damage in earlhquakes consistently exposes the predominant sources of weakness: insufficient, poorly executed structural details which received little or no attention within the design process. For this reason, great emphasis is placed in this book on the rational quantification of appropriate dealing. Wc gratefully acknowledge the support and encouragen~entreceived from our colleagues a t the University of Canterbury and the University of California-San Diego, and the research contributions of graduate students and technicians. Our special thanks are extendcd to Professor Robert Park, an inspiring member of our harmonious research team for more than 20 years, for his unfailing support during the preparation of this manuscript, which also made extensive use of his voluminous contributions to the design of structures for earthquake resistance. The constructive commcnts oflered by our collcagucs, especially Lhosc of Profcssor Hugo 13achmann and Konrad Moscr of the Swiss Federal Institute of Technology in Ziirich, improved the text. Further, we wish to acknowledge the effective support of the New Zealand National Society for Earthquake Engineering, which acted as a catalyst and coordinator of relevant contributions from all sections of the engineering profession, thus providing a significant source for this work. We are most grateful to Jo Johns, Joan Welle, Maria Martin, and especially Denise Forbes, who typed various chapters and their revisions, and to Valerie Grey for her careful preparation of almost all the illustrations. In the hope that our families will forgive us for the many hours which, instead of writing, we should have spent with them, we thank our wives for their support, care, patience, and above all their love, without which this book could not have been written.

Chrimhurch and Son Dicgo March 1991

CONTENTS 1 Introduction: Concepts of Seismic Design 1.1

1.2

1.3

1

Seismic Design and Seismic Performance: A Rcvicw 1 1.1.1 Seismic Design Limit States 8 (a) Serviceability Limit State 9 (b) Darnagc Control Limit Slatc 9 (c) Survival Limit Slate 10 1.1.2 Structural Properties 10 (a) Stiffness 10 (b) Strength 11 (c) Ductility 12 Essentials of Structural Systems for Seismic Resistance 13 1.2.1 Structural Systems for Seismic Forces 14 (a) Structural Frame Systems 14 (b) Structural Wall Systems 14 (c) Dual Systems 15 1.2.2 Gross Seismic Response 15 (a) Response in Elevation: The Building as a Vertical Cantilever 15 (b) Response in Plan: Centers of Mass and Rigidity 17 1.2.3 Influence of Building Configuration on Seismic Response 18 (a) Role of the Floor Diaphragm 19 (b) Amelioration of Torsional Effects 20 (c) Vertical Configurations 22 1.2.4 Structural Classification in Terms of Design Ductility Level 26 (a) Elastic Response 27 (b) Ductile Response 27 Definition of Design Quantities 29 1.3.1 Design Loads and Forces 29 (a) Dead Loads (D) 29 (b) Live Loads ( L ) 29 vii

viu

CONTENTS

1.4

(c) Earthquake Forces ( E l 30 (dl Wind Forces ( W ) 30 (el Other Forces 31 1.3.2 Design Combinations of Load and Force Effects 31 1.3.3 Strength Definitions and Relationships 33 (a) Required Strength (SJ 34 (b) Ideal Strength (S,) 34 (c) Probable Strength (S,) 34 (dl Overstrength (So) 35 (el Relationships between Strengths 35 (f) Flexural Overstrength Factor (4,) 35 (g) System Overstrength Factor ($,,I 37 1.3.4 Strength Reduction Factors 38 Philosophy of Capacity Design 38 1.4.1 Main Features 38 1.4.2 Illustrative Analogy 40 1.4.3 Capacity Design of Structures 42 1.4.4 Illustrative Example 43

2 Causes and Effects of Earthquakes: l + Seismic Action Seismicity -+ S t ~ c t u r aResponse 2.1

2.2

Aspects of Seismicity 47 2.1.1 Introduction: Causes and Effects 47 2.1.2 Seismic Waves 50 2.1.3 Earthquake Magnitude and Intensity 52 (a) Magnitude 52 (b) Intensity 52 2.1.4 Characteristics of Earthquake Accelerograms 54 (a) Accelerograms 54 (b) Vertical Acceleration 54 (c) Influence of Soil Stiffness 56 (dl Directionality Effects 57 (el Geographical Amplification 57 2.1.5 Attenuation Relationships 58 Choice of Design Earthquake 61 2.2.1 Intensity and Ground Acceleration Relationships 61 2.2.2 Return Periods: Probability of Occurrence 63 2.2.3 Seismic Risk 64 2.2.4 Factors Mecting Design Intensity 65 (a) Design Limit States 65 (b) Economic Considerations 67

CONTENTS

2.3

2.4

Dynamic Response of Structures 68 2.3.1 Response of Single-Degree-of-Freedom Systems to Lateral Ground Acceleration 69 (a) Stiffness 70 (b) Damping 70 (c) Period 71 2.3.2 Elastic Response Spectra 72 2.3.3 Response of Inelastic Single-Degree-of-Freedom Systems 73 2.3.4 Inelastic Response Spectra 76 2.3.5 Response of Multistory Buildings 79 Determination 'of Design Forces 79 2.4.1 Dynamic Inelastic Time-History Analysis 80 2.4.2 Modal Superposition Techniques 80 2.4.3 Equivalent Lateral Force Procedures 83 (a) First-Mode Period 84 (b) Factors Affecting the Seismic Base Shear Force 85 (c) Distribution of Base Shear over the Height of a Building 89 (d) Lateral Force Analysis 91 (e) Estimate of Deflection and Drift 92 (f) PA Effects in Frame Structures 92 (g) Torsion Effects 94

3 Principles of Member Design

3.1 3.2

Introduction 95 Materials 95 3.2.1 Unconfined Concrete 95 (a) Stress-Strain Curves for Unconfined Concrete 95 (b) Compression Stress Block Design Parameters for Unconfined Concrete 97 (c) Tension Strength of Concrete 98 3.2.2 Confined Concrete 98 (a) Confining Effect of Transverse Reinforcement 98 (b) Compression Stress-Strain Relationships for Conlined Concrete 101 (c) Influence of Cyclic Loading on Concrete Stress-Strain Relationship 103

ix

x

CONTENTS

(d) Effect of Strain Rate on Concrete Stress-Strain Relationship 103 (e) Compression Stress Block Design Parameters for Confined Concrete 104 3.2.3 Masonry 106 (a) Compression Strength of the Composite Material 108 (b) Ungrouted Masonry 109 (c) Grouted Concrete Masonry 111 (d) Grouted Brick Masonry 112 (e) Modulus of Elasticity 113 (f) Compression Stress-Strain Relationships for Unconfined and Confined Masonry 113 (g) Compressions Stress Block Design Parameters for Masonry 114 3.2.4 Reinforcing Steel 115 (a) Monotonic Characteristics 115 (b) Inelastic Cyclic Response 115 (c) Strain Rate Effects 117 (d) Temperature and Strain Aging Effects 117 (el Overstrength Factor (A,) 118 3.3 Analysis of Member Sections 118 3.3.1 Flexural Strength Equations for Concrete and Concrete Sections 118 (a) Assumptions 119 (b) Flexural Strength of Beam Sections 119 (c) Flexural Strength of Column and Wall Sections 121 3.3.2 Shear Strength 124 (a) Control of Diagonal Tension and Compression Failures 124 (b) Sliding Shear 129 (c) Shear in Beam-Column Joints 132 3.3.3 Torsion 132 3.4 Section Design 132 3.4.1 Strength Reduction Factors 133 3.4.2 Reinforcement Limits 134 3.4.3 Member Proportions 135 3.5 Ductility Relationships 135 3.5.1 Strain Ductility 136 3.5.2 Curvature Ductility 136 (a) Yield Curvature 136 (b) Maximum Curvature 138

CONTENTS

3.5.3 3.5.4

3.6

Displacement Ductility 139 Relationship between Curvature and Displacement Ductilities 140 (a) Yield Displacement 140 (b) Maximum Displacement 140 (c) Plastic Hinge Length 141 3.5.5 Member and System Ductilities 142 (a) Simultaneity in the Formation of Several Plastic Hinges 143 (b) Kinematic Relationships 144 (c) Sources of Yield Displacements and Plastic Displacements 144 3.5.6 Confirmation of Ductility Capacity by Testing 145 Aspects of Detailing 146 3.6.1 Detailing of Columns for Ductility 147 (a) Transverse Reinforcement for Confinement 147 (b) Spacing of Column Vertical Rcinforccmcnt 148 3.6.2 Bond and Anchorage 149 (a) Development of Bar Strength 149 (b) Lapped Splices 151 (c) Additional Considerations for Anchorages 153 3.4.3 Curtailment of Flexural Reinforcement 155 3.6.4 Transverse Reinforcement 156

4 Reinforced Concrete Ductile Frames 4.1

4.2

Structural Modeling 158 4.1.1 General Assumptions 158 4.1.2 Geometric Idealizations 160 4.1.3 Stiffness Modeling 162 Methods of Analysis 165 4.2.1 "Exact" Elastic Analyses 165 4.2.2 Nonlinear Analyses 165 4.2.3 Modified Elastic Analyses 165 4.2.4 Approximate Elastic Analyses for Gravity Loads 146 4.2.5 Elastic Analysis for Lateral Forces 168 (a) Planar Analysis 168 (b) Distribution of Lateral Forces between Frames 168 (c) Corrected Computer Analyscs 170 4.2.6 Regularity in the Framing System 171 fl

\

- 7

..

.

. r

*.

~:-. .,T*

xi

CONTENTS

XII

4.3

4.4

4.5

Derivation of Design Actions for Beams 172 4.3.1 Redistribution of Design Actions 172 4.3.2 Aims of Moment Redistribution 175 4.3.3 Equilibrium Requirements for Moment Redistribution 175 4.3.4 Guidelines for Redistribution 178 4.3.5 Examples of Moment Redistribution 180 4.3.6 Moment Redistribution in Inelastic Columns 182 4.3.7 Graphical Approach to the Determination of Beam Design Moments 183 Design Process 185 4.4.1 Capacity Design Sequence 185 (a) Beam Flexural Design 185 (b) Beam Shcar Design 186 (c) Column Flexural Strength 186 (d) Transverse Reinforcement for Columns 186 (el Beam-Column Joint Design 186 4.4.2 Design of Floor Slabs 186 Design of Beams 187 4.5.1 Flexural Strength of Beams 187 (a) Design for Flexural Strength 187 (b) Effective Tension Reinforcement 189 (c) Limitations to the Amounts of Flexural Tension Reinforcement 193 (d) Potential Plastic Hinge Zones 194 (el Flexural Overstrength of Plastic Hinges 199 (f) Beam Overstrength Factors (4,) 199 (g) System Overstrength Factor ($,) 200 (h) Illustration of the Derivation of Overstrength Factors 200 4.5.2 Development and Curtailment of the Flexural Reinforcement 204 4.5.3 Shear Strength of Beams 205 (a) Determination of Design Shear Forces 205 (b) Provisions for Design Shear Strength 207 4.5.4 Detailing Requirements 207 4.6 Design of Columns 210 4.6.1 Limitations of Existing Procedures 210 4.6.2 Deterministic Capacity Design Approach 211 4.6.3 Magnification of Column Moments Due to Flexural Overstrength of Plastic Hinges in Beams 212

CONTENTS

4.7

(a) Columns above Lcvel 2 212 (b) Columns of the First Story 214 (c) Columns in the Top Story 214 (dl Columns Dominated by Cantilever Action 215 4.6.4 Dynamic Magnification of Column Moments 215 (a) Columns of One-way Frames 217 (b) Columns of Two-way Frames 218 (c) Required Flexural Strength at the Column Base and in the Top Story 219 (dl Higher-Mode Effects of Dynamic Response 219 (el Columns with Dominant Cantilever Action 220 4.6.5 Column Design Moments 221 (a) Column Design Moments at Node Points 221 (b) Critical Column Section 222 (c) Reduction in Design Moments 223 4.6.6 Estimation of Design Axial Forces 225 4.6.7 Design Column Shear Forces 226 (a) Typical Column Shear Forces 226 (b) Design Shear in First-Story Columns 227 (c) Shear in Columns of Two-way Frames 227 (d) Shear in Top-Story Columns 228 4.6.8 Design Steps to Determine Column Design Actions: A Summary 228 4.6.9 Choice of Vertical Reinforcement in Columns 230 4.6.10 Location of Column Splices 232 4.6.11 Design of Transverse Reinforccmcnt 233 (a) General Considerations 233 (b) Configurations and Shapes of Transverse Reinforcement 234 (c) Shear Resistance 237 (d) Lateral Support for Compression Reinforcement 237 (e) Confinement of the Concrete 237 (f) Transverse Reinforcement at Lapped Splices 239 Frame Instability 240 4.7.1 P-A Phenomena 240 4,7.2 Current Approaches 240 4.7.3 Stability Index 241 4.7.4 Influence of PA Effects on Inelastic Dynamic Response 243 (a) Energy Dissipation 243 (b) Stiffness of Elastic Frames 244

xiii

xiv

CONTENTS

4.8

(c) Maximum Story Drift 245 (dl Ductility Demand 245 4.7.5 Strength Compensation 246 (a) Compensation for Losses in Energy Absorption 246 (b) Estimate of Story Drift 246 (c) Necessary Story Moment Capacity 247 4.7.6 Summary and Design Rccommcndations 248 Beam-Column Joints 250 4.8.1 General Design Criteria 250 4.8.2 Performance Criteria 252 4.8.3 Features of Joint Behavior 252 (a) Equilibrium Criteria 252 (b) Shear Strength 254 (c) Bond Strength 256 4.8.4 Joint Types Used in Frames 256 (a) Joints Affected by the Configuration of Adjacent Members 256 (b) Elastic and Inelastic Joints 257 4.8.5 Shear Mechanisms in Interior Joints 258 (a) Actions and Disposition of Internal Forces at a Joint 259 (b) Development of Joint Shear Forces 260 (c) Contribution to Joint Shear Strength of the Concrete Alone 261 (d) Contribution to'Joint Shear Strength of the Joint Shear Reinforcement 262 4.8.6 Role of Bar Anchorages in Developing Joint Strength 263 (a) Factors Affecting Bond Strength 263 (b) Required Average Bond Strength 265 (c) Distribution of Bond Forces within an Interior Joint 271 (d) Anchorages Requirements for Column Bars 273 4.8.7 Joint Shear Requirements 273 (a) Contributions of the Strut Mechanism (V,, and V,,) 273 (b) Contributions of the Truss Mechanism (V,, and 5,) 277 (c) Joint Shear Stress and Joint Dimensions 280 (d) Limitations of Joint Shear 281 (e) Elastic Joints 282

CONTENTS

4.8.9

Special Features of Interior Joints 285 (a) ContributiGn of Floor Slabs 285 (b) Joints with Unusual Dimensions 288 (c) Eccentric Joints 290 (d) Joints with Inelastic Columns 291 4.8.10 Alternative Detailing of Interior Joints 292 (a) Beam Bar Anchorage with Welded Anchorage Plates 292 (b) Diagonal Joint Shear Reinforcement 292 (c) Horizontally Haunched Joints 294 4.8.11 Mechanisms in Exterior Joints 294 (a) Actions at Exterior Joints 294 (b) Contributions of Joint Shear Mechanisms 295 (c) Joint Shear Reinforcement 297 (d) Anchorage in Exterior Joints 297 (e) Elastic Exterior Joints 301 4.8.12 Design Steps: A Summary 302 4.9 Gravity-Load-Dominated Frames 303 4.9.1 Potential Seismic Strength in Excess of That Required 303 4.9.2 Evaluation of the Potential Strength of Story Sway Mechanisms 305 4.9.3 Deliberate Reduction of Lateral Force Resistance 308 (a) Minimum Level of Lateral Force Resistance 308 (b) Beam Sway Mechanisms 310 (c) Introduction of Plastic Hinges in Columns 311 (d) Optimum Location of Plastic Hinges in Beams 312 4.9.4 Design for Shear 314 4.10 Earthquake-Dominated Tube Frames 314 4.10.1 Critical Design Qualities 314 4.10.2 Diagonally Reinforced Spandrel Beams 315 4.10.3 Special Detailing Requirements 316 4.10.4 Observed Beam Performance 318 4.11 Examples in the Design of an Eight-Story Frame 319 4.11.1 General Description of the Project 319 4.11.2 Material Properties 319 4.11.3 Specified Loading and Design Forces 319 (a) Gravity Loads 319 (b) Earthquake Forces 321 .-

-

.

"--

.

",.A

xv

CONTENTS

4.11.5 4.11.6

4.1 1.7

4.11.8

4.11.9

(a) Members of East-West Frames 321 (b) Members of North-South Frames 323 G...