1123_fmprecast Seismic Design of Reinforced

SEISMIC DESIGN OF REINFORCED AND PRECAST CONCRETE BUILDINGSROBERT E. ENGLEKIRK Consulting Structural Engineer and Adjunct Professor University of California at San Diego JOHN WILEY & SONS, INC. Copyright © 2003 John Wiley & Sons Retrieved from: www.knovel.com com. TA658. New Jersey. No part of this publication may be reproduced. Danvers. or other damages. visit our web site at www. e-mail: [email protected] 2003 693. they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. 2. recording. Hoboken. Requests to the Publisher for permission should be addressed to the Permissions Department. please contact our Customer Care Department within the United States at (800) 762-2974. fax (201) 748-6008. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book. without either the prior written permission of the Publisher. 10 9 8 7 6 5 4 3 2 1 Copyright © 2003 John Wiley & Sons Retrieved from: www.com..com . No warranty may be created or extended by sales representatives or written sales materials. scanning or otherwise. Inc. or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center. Published by John Wiley & Sons.knovel. incidental. The advice and strategies contained herein may not be suitable for your situation. Buildings. Earthquake resistant design. All rights reserved. electronic.44 .. NJ 07030. (978) 750-8400. or on the web at www. p. You should consult with a professional where appropriate. Copyright © 2003 by John Wiley & Sons. cm. Wiley also publishes its books in a variety of electronic formats. I. except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act. ISBN 0-471-08122-1 1. Inc.com. (201) 748-6011. For general information on our other products and services or for technical support. including but not limited to special.copyright. or transmitted in any form or by any means. fax (978) 750-4470. outside the United States at (317) 572-3993 or fax (317) 572-4002. Inc. For more information about Wiley products. Precast concrete construction. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages.8'52—dc21 2002008561 Printed in the United States of America. Hoboken. 3. Library of Congress Cataloging-in-Publication Data: Englekirk. 1936– Seismic design of reinforced and precast concrete buildings / Robert Englekirk. Robert E. Title. MA 01923. consequential. 222 Rosewood Drive. Reinforced concrete construction.. 4. Some content that appears in print may not be available in electronic books. Reinforced concrete—Earthquake effects. Published simultaneously in Canada.wiley.This book is printed on acid-free paper. stored in a retrieval system. photocopying. John Wiley & Sons. mechanical. 111 River Street. once stretched by a new idea.” —Oliver Wendell Holmes Knowledge and imagination are essential components of the design process. not the algorithm. To this end Chapters 1 and 2 review experimental evidence and selected fundamental principles in search of appropriate design processes and limit states. My hope is to advance the reader’s ability to design by reducing existing experimentally developed conclusions to design-relevant relationships and limit states. Engineers are generally characterized as unimaginative or pedantic in their approach to problems. whether contained in a black box or reduced to napkin form. the scientific data used to support xiii Copyright © 2003 John Wiley & Sons Retrieved from: www. The reduction of experimental data to a usable form is essential to the design process because an engineer.com . who is responsible for the building design and safety of the building’s occupants. not constrain a design to a particular approach or set of limit states.PREFACE “Man’s mind. for I believe that all design procedures must be thoroughly understood and accepted by the user if they are to be appropriately applied. and this is because it is the engineer. especially if the basic principle is not a part of his or her working vocabulary. Algorithms. faced with a design decision. because none of these structures were developed from scientifically supportable data. or experimental data. are an essential part of the designer’s vocabulary.knovel. This generalization is not supported by historical evidence. and the modern structures of today. in our modern scientifically based society that probes the universe. Behavior models must also be available to and accepted by the designer. which from a structural perspective includes the creation of ancient structures. Imagination without knowledge will quite often produce designs that are dangerous. The algorithms developed herein are presented in sufficient detail so as to allow the user to adapt them to his or her predilection or interpretation of experimental evidence. cannot confidently develop a design approach from experiment data or basic principles as a part of each design. never regains its original dimensions. medieval cathedrals. black box. Even today. The development and integration of these themes is the objective of this book. Knowledge absent imagination can only produce designs of limited scope. My objective in Chapters 1 and 2 is to stretch the reader’s mind. The thrust of this book is to produce structural systems that can be shown by rational analysis and experimental evidence to be capable of attaining performance objectives when subjected to design-level earthquakes. and my cardiology team.knovel. Exploring all possible uses of imaginative thinking is impossible so I have tried to develop several imaginative approaches by example and where possible relate these specific examples to a generalization of the design objective. this book would not exist. Imagination cannot be taught. Building codes. Tom Paulay. My thanks also to Kimberly Tanouye for her design contribution to the cover. The comments of you. A special expression of gratitude is also extended to those who have taken the time and made the effort to translate ideas and research into the written word on the subject of concrete and earthquake engineering—my good friends and colleagues. The assistance of my associates is gratefully acknowledged and especially that of Nagi Abo-Shadi. and Nigel Priestley. Copyright © 2003 John Wiley & Sons Retrieved from: www. in particular. I dedicate this book to my family and. who converted my crude sketches to an art form. One writes with the assistance of a dictionary—we do not use the dictionary to write. The existence of codified relationships expressed in four significant figures only tends to suppress an engineer’s imagination by creating a scientific illusion.com . but it can be released and encouraged by removing suppressants. Robert Liu. and Michael Riddell. Kahn. It is also effectively used to extend experimental evidence. Dan Shubin. to my wife. who not only typed but managed the processing of this manuscript. Imagination can and must be effectively used to apply basic concepts to complex problems. Drs. Richard Chen. Natalie. The concepts explored in this book are more simply applied than explained. like dictionaries. whose patience and understanding allowed for its development. My hope is that the material contained herein will encourage the development of a dialogue that will result in a more rational approach to the seismic design of concrete buildings. and Robertson. The exploitation of precast concrete as a seismic resisting system clearly demonstrates how imagination can be used to create better structural systems. Natterson. ACKNOWLEDGMENTS Absent the dedicated efforts of Joan Schulte. and this is the objective of Chapters 3 and 4. So it should be with design. are essential tools of the trade.xiv PREFACE building design are more speculative than scientific. will be appreciated. and it is for this reason that I do not choose to describe or explain design using the building code as a basis. Bob Park. the reader. The joint depth is the overall depth of the column. usually subscripted for definition purposes Effective cross-sectional area within a joint in a plane parallel to plane of reinforcement generating shear in the joint. Area of prestressed reinforcement in tension zone Area of nonprestressed tension reinforcement Area of compression reinforcement Total cross-sectional area of transverse reinforcement (including crossties) within spacings Total area of longitudinal reinforcement Loaded area xv Copyright © 2003 John Wiley & Sons Retrieved from: www.2248 kips 1 kN-m = 0.737 ft-kips 1 MPa = 1000 kN/mm2 ADOPTED NOMENCLATURE A Aj Aps As As Ash Ast A1 Area. The effective width will depend to a certain extent on the size of the beams framing into the joint.com .knovel.NOMENCLATURE I have chosen to use both English and metric units so as not to alter the graphic description of experimental data. The following conversions are standard: 1 m = 39.37 in. 1 kN = 0. usually subscripted to identify load type or strength state Nominal axial load strength at balanced conditions of strain Nominal axial load strength at zero eccentricity Prestressing load applied to a high-strength bolt Stability index for a story—elastic basis (see Section 4. usually subscripted to identify condition Yield strength of structural steel Overall height of frame Moment of inertia of cracked section transformed to concrete Effective moment of inertia Moment of inertia of gross concrete section about centroidal axis. or related internal moments and forces Moment in member. or stress state Mass subscripted when appropriate to identify (e) effective or (1) contributing mode Nominal moment strength at balanced conditions of strain Cracking moment Elastic moment Probable flexural moment strength of members. usually subscripted to identify loading condition. or related internal moments and forces. neglecting reinforcement Live loads. member.1) Stability index for a story—inelastic basis (see Section 4.1) Spectral reduction factor Spectral acceleration—in. modulus of elasticity usually subscripted to identify material Flexural stiffness Loads attributable to strength of provided reinforcement. or tapered wedge contained wholly within the support and having for its upper base the loaded area and having side slopes of 1 vertical to 2 horizontal Compressive force—subscripted when qualification is required Force imposed on the compression diagonal Dead loads.3. with or without axial load./sec Spectral acceleration expressed as a percentage of the gravitational force g Spectral displacement Spectral velocity Copyright © 2003 John Wiley & Sons Retrieved from: www. cone.xvi A2 NOMENCLATURE C Cd D DR E EI F Fy H Icr Ie Ig L M M Mbal Mcr Mel Mpr N P Pb Po Ppre Q Q∗ ˆ R Sa Sag Sd Sv The area of the lower base of the largest frustum of a pyramid. depth of frame Drift ratio ( x / hx ) or ( n /H ) Load effects of seismic forces. determined using the probable properties of the constitutive materials An integer usually applied to number of bays or number of connectors Axial load.com .knovel.3. NOMENCLATURE xvii SF U V Vc Vch VN Vsh W W a b bw c cc d d ˙ d ¨ d d db ds dps dz e f fc fci fci fcr fct Square feet Required strength to resist factored loads or related internal moments and forces Shear force usually quantified to describe associated material or contributing load Shear strength provided by concrete Nominal capacity of the concrete strut in a beam-column joint Component of joint shear strength attributed to the axial load imposed on a column load Nominal strength of diagonal compression field Wind load Weight (mass) tributary to a bracing system Depth of equivalent rectangular stress block.com . measure of stress. usually subscripted to identify condition of interest Specified compressive strength of concrete Compressive strength of concrete at time of initial prestress Square root of compressive strength of concrete at time of initial prestress Critical buckling stress Average splitting tensile strength of aggregate concrete Copyright © 2003 John Wiley & Sons Retrieved from: www.knovel. shear span Width of compression face of member Web width Distance from extreme compression fiber to neutral axis Clear cover from the nearest surface in tension to the surface of the flexural tension reinforcement Distance from extreme compression fiber to centroid of tension reinforcement Displacement (peak) of the ground Velocity (peak) of the ground Acceleration (peak) of the ground Distance from extreme compression fiber to centroid of compression reinforcement Bar diameter Distance from extreme compression fiber to centroid of tension conventional reinforcement Distance from extreme compression fiber to centroid of prestressed reinforcement Depth of the plate Eccentricity of axial load Friction factor. acceleration. 2.6] Eq.0 for bottom bars. 1.3 for top bars. 12. system stiffness usually subscripted to identify objective Elastic stiffness Secant stiffness Depth of neutral axis—elastic behavior is assumed Span length of beam center to center of supporting column Clear span of beam from face to face of supporting column Development length for a straight bar Development length for a bar with a standard hook Length of entire wall or of segment of wall considered in direction of shear force An integer usually applied to number of floors Radius of gyration of cross section of a compression member Spacing of transverse reinforcement Thickness of grout Unit weight Width of steel plate Distance from centroidal axis of gross section. to extreme fiber in tension Factor in bar development length evaluation.6] Eq. See ACI.2 α β Copyright © 2003 John Wiley & Sons Retrieved from: www.xviii fcg fpse fpy fr fs fsc fy fyh h hc hn hw hx k kel ksec kd NOMENCLATURE c d dh w n r s tg w wz yt Stress in the grout Effective stress in prestressed reinforcement (after allowance for all prestress losses) Specified yield strength of prestressing tendons Modulus of rupture of concrete Calculated stress in reinforcement Stress in compression steel Specified yield strength of reinforcement Specified yield strength in hoop reinforcing Overall thickness of member Cross-sectional dimension of column core measured center-to-center of confining reinforcement Height of the uppermost level of a frame Height of entire wall or of the segment of wall considered Maximum horizontal spacing of hoop or crosstie legs on all faces of the column.com . 1. [2.2. See ACI. neglecting reinforcement.2 Coating factor. story height Effective length factor for compression members. [2.knovel. 12. 6] Postyield shearing angle Participation factor Member or component displacement An increment of force. friction factor Displacement ductility factor Strain ductility factor Rotation ductility factor Curvature ductility factor Ratio of nonprestressed tension reinforcement.NOMENCLATURE xix β1 γp δu n x ε ζ ˆ ζ θ λ λo µ µ µε µθ µφ ρ ρ ρb ρg ρs ρv φ φe φk φp ω ω ωp o Factor that defines the relationship between the depth of the compressive stress block and the neutral axis depth.knovel.com . stress. strength reduction factor Normalized elastic displacement ( i / u ) Stiffness reduction factor Probable overstrength of the steel Reinforcement index ρfy /fc Reinforcement index ρ fy /fc Reinforcement index ρp fps /fc System overstrength factor Copyright © 2003 John Wiley & Sons Retrieved from: www. capacity-based reduction factor. As /bd Reinforcement ratio producing balanced strain conditions Ratio of total reinforcement area to cross-sectional area of column Ratio of volume of spiral reinforcement to total volume of core (out-to-out of spirals) of a spirally reinforced compression member Ratio of area of distributed reinforcement perpendicular to the plane of Acv to gross concrete area Acv Curvature. bond stress. or strain Relative lateral deflection between the uppermost level and base of a building Relative lateral deflection between the top and bottom of a story Strain—usually subscripted to describe material or strain state Structural damping coefficient expressed as a percentage of critical damping Total damping coefficient expressed as a percentage of critical damping Rotation Lightweight aggregate concrete factor Component or member overstrength factor that describes overstrength expected in a member Ductility factor usually subscripted. c [2. rad/in. As /bd Ratio of nonprestressed compression reinforcement.. shear component of deformation f . column b. service or stress limit state (unfactored) u. minimum permitted M. Multiple subscripts will be used where appropriate. max. yield max. i will also be used to identify an idealized condition such as yield: e. pr. p. mechanism 2. n. D. c. s. R and 1. live load D. C. s. f . maximum permitted min. exterior beam or column i. i will be used to describe a location. u. beam s. postyield component of deformation 3. earthquake load 5. L. y.xx NOMENCLATURE SPECIAL SUBSCRIPTS Special subscripts will follow a notational form to the extent possible.com .knovel. and they will be developed as follows: 1. idealized y. interior beam or column 4. L. probable i. ultimate or factored capacity (strength) n. 2 will be used to locate an event with reference to a specific plan grid or point: L. flexural component of deformation p. postyield pr. left R. B. right Example: Mcui Interior Ultimate or factored Column MbCsD Dead load Unfactored Grid line C Beam MuD Dead load Factored Copyright © 2003 John Wiley & Sons Retrieved from: www. A. nominal capacity p. b. E will be used to describe a load condition: L. i. e. and M will be used to describe member strength or deformation state: s. and p will be used to describe a member category or characterize a system behavior condition: c. dead load E. Special subscripts will be used to identify the following: a.com . compression CB. energy dissipater g. compression bottom CT. design. Capitalized subscripts will be used to describe the stress class and its location: B. tension top 7. degrading or diaphragm ed. tension bottom TT. single-degree-of-freedom system Copyright © 2003 John Wiley & Sons Retrieved from: www. compression top T. transverse TB. as in design basis D.NOMENCLATURE xxi 6. top. tension. bottom C. attainable or average d.knovel. grout SDOF.