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2020 N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP RESEARCH REPORT 949 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Thomas P. Murphy Modjeski and Masters, inc. Mechanicsburg, PA Lee Marsh Stuart Bennion BergeraBaM Federal Way, WA Ian G. Buckle University of nevada, reno Reno, NV Nicolas Luco U.s. geological sUrvey Reston, VA Donald Anderson cH2M Hill Corvallis, OR Mervyn Kowalsky nortH carolina state University Raleigh, NC Jose Restrepo advanced analysis and design, llc Alpine, CA Subscriber Categories Bridges and Other Structures Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniquesâthe National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration (FHWA), United States Department of Transportation, under Agree- ment No. 693JJ31950003. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRBâs recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRBâs relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs iden- tified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&Iâs recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement, rather than to substitute for or duplicate, other highway research programs. Published research reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet by going to https://www.nationalacademies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 949 Project 12-106 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-48177-9 Library of Congress Control Number 2020942362 Â© 2020 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FTA, GHSA, NHTSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The research report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; the FHWA; or the program sponsors. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of the report.
The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. The Boardâs varied activities annually engage about 8,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.
C O O P E R A T I V E R E S E A R C H P R O G R A M S AUTHOR ACKNOWLEDGMENTS The research was performed and the research report prepared under NCHRP Project 12-106 by a research team led by Modjeski and Masters, Inc., with Thomas P. Murphy as the principal investigator, supported by Travis Hopper, Diane Long, and Maria Lopez. The research team also consisted of Lee Marsh and Stuart Bennion of BergerABAM; Ian G. Buckle of the University of Nevada, Reno; Nico Luco of the U.S. Geological Survey; Donald Anderson of CH2M Hill; Mervyn Kowalsky of North Carolina State University; and Jose Restrepo of Advanced Analysis and Design, LLC. CRP STAFF FOR NCHRP RESEARCH REPORT 949 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Waseem Dekelbab, Senior Program Officer Tyler Smith, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Linda A. Dziobek, Senior Editor NCHRP PROJECT 12-106 PANEL Field of DesignâArea of Bridges Thomas A. Ostrom, California DOT, Sacramento, CA (Chair) Richard A. Pratt, Alaska DOT and Public Facilities, Juneau, AK Xiaohua Hannah Cheng, New Jersey DOT, Trenton, NJ Timothy E. Huff, Tennessee Tech University, Cookeville, TN Bijan Khaleghi, Washington State Department of Transportation, Olympia, WA Mark D. Shaffer, Illinois DOT, Springfield, IL W. Phillip Yen, International Association of Bridge Earthquake Engineering, Centreville, VA (Deceased) Jeffrey Ger, FHWA Liaison Stephen F. Maher, TRB Liaison
NCHRP Research Report 949: Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design presents a methodology to analyze and determine the seismic capacity requirements of bridge elements expressed in terms of service and damage levels of bridges under a seismic hazard. The methodology is presented as proposed AASHTO guidelines for performance-based seismic bridge design with ground motion maps and detailed design examples illustrating the application of the proposed guidelines and maps. This report will be of immediate interest to bridge engineers. The current AASHTO Guide Specifications for LRFD Seismic Bridge Design âguide specifi- cationsâ do not address performance-based seismic bridge design or provide design criteria for bridges that are critical or essential. Furthermore, the AASHTO guide specifications do not provide direction to assist owners and designers who wish to consider seismic risk mitigation beyond the life safety objective. A bridge may have different operational require- ments depending on the post-earthquake functions (e.g., serving the community by pro- viding emergency vehicle access), which would suggest a higher performance objective than the basic levels included in the design codes. Research was needed to provide guidance to help bridge owners and designers define enhanced seismic performance objectives and design bridges to meet those objectives. Modjeski and Masters, Inc., performed research under NCHRP Project 12-106, âProposed Guidelines for Performance-Based Seismic Bridge Design,â to develop the following: â¢ Proposed AASHTO guidelines for performance-based seismic bridge design, â¢ Proposed revisions to the AASHTO Guide Specifications for LRFD Seismic Bridge Design to link with the proposed AASHTO guidelines for performance-based seismic bridge design, and â¢ Proposed ground motion maps for inclusion in the AASHTO LRFD Bridge Design Speci- fications, as well as the AASHTO Guide Specifications for LRFD Seismic Bridge Design. Two deliverables were provided as appendices and are not included within the published report but are available on TRBâs website at www.trb.org by searching on NCHRP Research Report 949. The appendices are as follows: Appendix A: SDOF Column Investigation Sample Calculations and Results Appendix B: Hazard Comparison F O R E W O R D By Waseem Dekelbab Staff Officer Transportation Research Board
1 Summary 3 Chapter 1 Introduction 3 Background 3 Research Objectives 4 Chapter 2 Literature Review and Synthesis 4 Literature Review 4 Purpose of Literature Review 4 Literature Review Process 5 Synthesis of PBSD (2012â2016) 5 Objectives of NCHRP Synthesis 440 6 Public and Engineering Expectations of Seismic Design and the Associated Regulatory Framework 10 Seismic Hazard Prediction 17 Structural Analysis and Design 24 Damage Analysis 25 Loss Analysis 27 Organization-Specific Criteria for Bridges and Project-Specific Criteria 34 Identification of Knowledge Gaps 37 Chapter 3 Development of the AASHTO Guidelines for Performance-Based Seismic Design 37 Goals of PBSD 38 Steps to Achieve PBSD 39 Operational Categories 41 Performance Levels 42 Engineering Design Parameters 43 Strain Limits 47 Translating Limit State Strains to Member Deformations 49 Approach Fill Rotation and Displacement Limits 52 Geometric Displacement Limits 52 Demand Analysis and Capacity Assessment Requirements 53 Seismic Hazard 54 Seismic Design Category 54 Geoseismic Hazards and Liquefaction Assessment 56 Earthquake Resisting Systems 57 Capacity Design 57 Design Examples C O N T E N T S
58 Chapter 4 AASHTO Seismic Map Update 58 Background Information 60 Option 1â2014 Hazard Model 3-Period Spectrum 60 Option 2â2018 Hazard Model 3-Period Spectrum 60 Option 3â2018 Hazard Model Multi-Period Spectra 60 Hazard Models Considered 60 Map Development and Comparison Effort 63 Summary of Comparisons and Recommendations 66 Chapter 5 Conclusions and Suggested Research 66 Conclusions 66 Suggested Research 67 References and Bibliography 75 Appendices Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions.