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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 935 Proposed AASHTO Seismic Specifications for ABC Column Connections M. Saiid Saiidi Mehrdad Mehraein Grishma Shrestha Evan Jordan Ahmad Itani University of nevada, reno Reno, NV Mostafa Tazarv soUth dakota state University Brookings, SD David Sanders iowa state University Ames, IA Thomas P. Murphy Modjeski and Masters, inc. Mechanicsburg, PA Mark L. Reno Martin N. Pohll QUincy engineering, inc. Rancho Cordova, 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 http://www.national-academies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 935 Project 12-105 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-48131-1 Library of Congress Control Number 2020935050 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.national-academies.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 reported herein was performed under NCHRP Project 12-105 by the University of Nevada, Reno (UNR), in collaboration with South Dakota State University, Modjeski and Masters, Inc., and Quincy Engineering, Inc. The principal investigator (PI) on this project was M. Saiid Saiidi of UNR. Mostafa Tazarv of South Dakota State University, Ahmad Itani of UNR, David Sanders of Iowa State University, Thomas P. Murphy of Modjeski and Masters, Inc., and Mark Reno and Martin Pohll of Quincy Engineering, Inc., were co-PIs on the project. Co-PI Tazarv, under the supervision of the PI, performed the state-of-the-art literature review and the analytical studies and developed preliminary design equations and the coupler standard testing methods. Research associate Mehrdad Mehraein (now with HNTB Corporation, Bellevue, WA) performed the detailed finite element analyses of precast column connections under the supervision of PI Saiidi and Co-PI Tazarv. Research associate Grishma Shrestha (now with Civiltech Engineering, Bellevue, WA) and research assistant Evan Jordan (now with Magnusson Klemencic Associates, Seattle, WA) performed the experimental work of the project under the supervision of the PI. Thomas Murphy wrote the design and construction specifications in the code format and language. Martin Pohll and Mark Reno developed the design examples. The authors thank BarSplice Products, Inc., Headed Reinforcement Corp., and Splice Sleeve North America, Inc., for material donations. Patrick Laplace, Chad Lyttle, and Todd Lyttle of the UNR Earth- quake Engineering Laboratory are thanked for their assistance in the experimental studies for this project. CRP STAFF FOR NCHRP RESEARCH REPORT 935 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Waseem Dekelbab, Senior Program Officer Jarrel McAfee, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Janet M. McNaughton, Senior Editor NCHRP PROJECT 12-105 PANEL Field of DesignâArea of Bridges Michael D. Keever, California DOT, Sacramento, CA (Chair) Bijan Khaleghi, Washington State DOT, Olympia, WA Timothy E. Huff, Tennessee Tech University, Cookeville, TN Elmer E. Marx, Alaska DOT and Public Facilities, Juneau, AK Eric E. Matsumoto, California State UniversityâSacramento, Sacramento, CA Derek Soden, FHWA Liaison Stephen F. Maher, TRB Liaison
This report presents proposed AASHTO seismic specifications related to the design and construction of column connections for accelerated bridge construction (ABC) with detailed design examples illustrating the application of the proposed specifications. The proposed specifications are based on comprehensive analytical and testing programs for investigating the performance of different ABC column connections, including mechanical bar couplers, grouted ducts, and pocket and socket connections in moderate- and high- seismic regions. This report will be of immediate interest to bridge engineers. During NCHRP Domestic Scan 11-02, âBest Practices Regarding Performance of ABC Connections in Bridges Subjected to Multihazard and Extreme Events,â it was noted that ABC techniques have been limited in moderate- and high-seismic regions. The AASHTO Guide Specifications for LRFD Seismic Bridge Design currently prohibit or limit connections that splice longitudinal column reinforcement in plastic hinge regions. To address this limitation, there was a need to identify column connections that are capable of performing well in seismic regions. Research was performed under NCHRP Project 12-105, âProposed AASHTO Seismic Specifications for ABC Column Connections,â by the University of Nevada, Reno, to develop proposed AASHTO displacement-based design and construction specifications for implementation of ABC column connections in moderate- and high-seismic regions. The specifications included mechanical bar couplers, grouted ducts, and pocket and socket connections. Several deliverables, provided as appendices, are not included in the report itself but are available on the TRB website (trb.org) on the web page for NCHRP Project 12-105. These appendices are titled as follows: Appendix A: Survey of State Departments of Transportation Appendix B: Proposed AASHTO/ASTM Standard Test Method for Bar Couplers Appendix C: Proposed AASHTO Specifications for ABC Columns Appendix D: Detailed Design Examples F O R E W O R D By Waseem Dekelbab Staff Officer Transportation Research Board
1 Summary 3 Chapter 1 Introduction 3 1.1 Problem Statement 3 1.2 Research Objectives 4 1.3 Organization 4 1.4 References 5 Chapter 2 State-of-the-Art Literature Review 5 2.1 Introduction 6 2.2 Mechanical Bar Splices 6 2.2.1 Introduction 7 2.2.2 Couplers in U.S. Codes 8 2.2.3 Shear Screw Couplers 16 2.2.4 Headed Bar Couplers 21 2.2.5 Grouted Couplers 28 2.2.6 Threaded Couplers 33 2.2.7 Swaged Couplers 34 2.2.8 Mechanically Spliced Column Field Application 36 2.3 Grouted Duct Connections 36 2.3.1 Introduction 36 2.3.2 Previous Studies 49 2.3.3 Summary of Grouted Duct Connection Tests 49 2.3.4 Grouted Duct Column Field Application 49 2.4 Pocket and Socket Connections 49 2.4.1 Introduction 50 2.4.2 Previous Studies 70 2.4.3 Summary of Pocket/Socket Connection Tests 70 2.4.4 Pocket/Socket Connection Field Application 73 2.5 Pipe-Pin Connections 73 2.5.1 Introduction 75 2.5.2 Previous Studies 83 2.5.3 Summary of Pipe-Pin Connection Tests 83 2.5.4 Pipe-Pin Connection Field Application 83 2.6 Analytical Studies of ABC Column Connections 83 2.6.1 Introduction 84 2.6.2 Mechanically Spliced Columns 87 2.6.3 Grouted Duct Connections 87 2.6.4 Pocket and Socket Connections 90 2.6.5 Pipe-Pin Connections 90 2.6.6 Summary of Analytical Studies C O N T E N T S
91 2.7 Issues to Address Before Field Deployment of Precast Bridge Columns 91 2.7.1 Knowledge Gaps 94 2.7.2 Constructability 96 2.7.3 Maintenance 96 2.7.4 Speed of Construction and Cost 96 2.7.5 Summary 97 2.8 References 101 Chapter 3 Experimental Programs 101 3.1 Introduction 101 3.2 Mechanical Bar Splices 101 3.2.1 Coupler Rigid Length Ratio 103 3.2.2 Experimental Studies and Results for Grouted Sleeve Splices 108 3.2.3 Experimental Studies and Results for Headed Bar Splices 114 3.2.4 Experimental Studies and Results for Swaged Splices 120 3.2.5 Coupler Rigid Length Ratios 122 3.2.6 Strain Rate for Dynamic Loading of Spliced Bars 123 3.2.7 Summary of Mechanical Bar Splice Testing 124 3.3 Mechanically Spliced Bridge Columns 124 3.3.1 Introduction 124 3.3.2 Column Model 128 3.3.3 Test Results for GC10 Column Model 140 3.3.4 Summary of Mechanically Spliced Column Testing 140 3.4 Grouted Duct Connections 140 3.4.1 Introduction 141 3.4.2 Grouted Duct Test Models 142 3.4.3 Material Properties, Instrumentation, and Testing Procedure for Grouted Duct Connections 147 3.4.4 Results of Grouted Duct Connection Tests 148 3.4.5 Summary of Grouted Duct Connection Testing 151 3.5 Testing of Other Types of Connections 151 3.6 References 152 Chapter 4 Analytical Programs 152 4.1 Introduction 152 4.2 Mechanical Bar Splices 154 4.2.1 Proposed Acceptance Criteria for Mechanical Bar Splices 155 4.2.2 Proposed Material Model for Mechanical Bar Splices 156 4.2.3 Proposed Method of Testing for Mechanical Bar Splices 157 4.2.4 Validation of Proposed Material Model for Mechanical Bar Splices 158 4.3 Mechanically Spliced Bridge Columns 160 4.3.1 Parametric Studies 168 4.3.2 Proposed Equation for Reduction of Ductility Capacity 170 4.3.3 Proposed Modified Plastic Hinge Length 171 4.3.4 Effects of Bar Debonding on Performance of Mechanically Spliced Columns 177 4.3.5 Summary of Modeling Methods for Mechanically Spliced Columns 177 4.3.6 Multicolumn Bents with Mechanically Spliced Columns 178 4.3.7 Testing Method for Mechanically Spliced Columns 178 4.3.8 Summary of Study on Mechanically Spliced Bridge Columns
178 4.4 Grouted Duct Design Equation 178 4.4.1 Bond Behavior of Grouted Duct Connections 180 4.4.2 Previous Test Data 182 4.4.3 Preliminary Proposed Design Equation for Grouted Ducts 182 4.4.4 Updated Pullout Test Database for Grouted Duct Connections 184 4.4.5 Updated Design Equation and Guidelines for Grouted Duct Connections 187 4.4.6 Summary of Study on Grouted Duct Design Equation 188 4.5 Grouted Duct Column Connections 188 4.5.1 Grouted Duct Connection Finite Element Modeling 189 4.5.2 Typical Oversized Pile Shaft Grouted Duct Connections 196 4.5.3 Cap Beam Grouted Duct Connections 204 4.5.4 Summary of Study on Grouted Duct Column Connections 205 4.6 Pocket Connections 205 4.6.1 Pocket Connection Finite Element Modeling 219 4.6.2 Typical Oversized Pile Shaft Pocket Connections 222 4.6.3 Cap Beam Pocket Connections 232 4.6.4 Design and Detailing Guidelines for Pocket Connections 232 4.6.5 Summary of Study on Pocket or Socket Column Connections 232 4.7 References 235 Chapter 5 Proposed Specifications and Examples 235 5.1 Introduction 235 5.2 Proposed Standard Testing Methods for Mechanical Bar Splices 236 5.3 Proposed Specifications for Precast Column Connections 236 5.3.1 Mechanically Spliced Column Connections 236 5.3.2 Grouted Duct Connections 237 5.3.3 Pocket/Socket Connections 237 5.4 Design Examples 238 5.5 References 239 Chapter 6 Summary and Conclusions 239 6.1 Summary 240 6.2 Conclusions 240 6.2.1 Literature Review and Survey of State Departments of Transportation and Other Agencies 241 6.2.2 Experimental Programs 241 6.2.3 Analytical Programs 242 6.2.4 Proposed Specifications and Examples 242 6.3 References 243 Acronyms 244 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.