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NATIONAL
NCHRP REPORT 681
COOPERATIVE
HIGHWAY
RESEARCH
PROGRAM
Development of
a Precast Bent Cap System
for Seismic Regions
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TRANSPORTATION RESEARCH BOARD 2010 EXECUTIVE COMMITTEE*
OFFICERS
CHAIR: Michael R. Morris, Director of Transportation, North Central Texas Council of Governments, Arlington
VICE CHAIR: Neil J. Pedersen, Administrator, Maryland State Highway Administration, Baltimore
EXECUTIVE DIRECTOR: Robert E. Skinner, Jr., Transportation Research Board
MEMBERS
J. Barry Barker, Executive Director, Transit Authority of River City, Louisville, KY
Allen D. Biehler, Secretary, Pennsylvania DOT, Harrisburg
Larry L. Brown, Sr., Executive Director, Mississippi DOT, Jackson
Deborah H. Butler, Executive Vice President, Planning, and CIO, Norfolk Southern Corporation, Norfolk, VA
William A.V. Clark, Professor, Department of Geography, University of California, Los Angeles
Eugene A. Conti, Jr., Secretary of Transportation, North Carolina DOT, Raleigh
Nicholas J. Garber, Henry L. Kinnier Professor, Department of Civil Engineering, and Director, Center for Transportation Studies, University of
Virginia, Charlottesville
Jeffrey W. Hamiel, Executive Director, Metropolitan Airports Commission, Minneapolis, MN
Paula J. Hammond, Secretary, Washington State DOT, Olympia
Edward A. (Ned) Helme, President, Center for Clean Air Policy, Washington, DC
Adib K. Kanafani, Cahill Professor of Civil Engineering, University of California, Berkeley
Susan Martinovich, Director, Nevada DOT, Carson City
Debra L. Miller, Secretary, Kansas DOT, Topeka
Sandra Rosenbloom, Professor of Planning, University of Arizona, Tucson
Tracy L. Rosser, Vice President, Corporate Traffic, Wal-Mart Stores, Inc., Mandeville, LA
Steven T. Scalzo, Chief Operating Officer, Marine Resources Group, Seattle, WA
Henry G. (Gerry) Schwartz, Jr., Chairman (retired), Jacobs/Sverdrup Civil, Inc., St. Louis, MO
Beverly A. Scott, General Manager and Chief Executive Officer, Metropolitan Atlanta Rapid Transit Authority, Atlanta, GA
David Seltzer, Principal, Mercator Advisors LLC, Philadelphia, PA
Daniel Sperling, Professor of Civil Engineering and Environmental Science and Policy; Director, Institute of Transportation Studies; and Interim
Director, Energy Efficiency Center, University of California, Davis
Kirk T. Steudle, Director, Michigan DOT, Lansing
Douglas W. Stotlar, President and CEO, Con-Way, Inc., Ann Arbor, MI
C. Michael Walton, Ernest H. Cockrell Centennial Chair in Engineering, University of Texas, Austin
EX OFFICIO MEMBERS
Peter H. Appel, Administrator, Research and Innovative Technology Administration, U.S.DOT
J. Randolph Babbitt, Administrator, Federal Aviation Administration, U.S.DOT
Rebecca M. Brewster, President and COO, American Transportation Research Institute, Smyrna, GA
George Bugliarello, President Emeritus and University Professor, Polytechnic Institute of New York University, Brooklyn; Foreign Secretary,
National Academy of Engineering, Washington, DC
Anne S. Ferro, Administrator, Federal Motor Carrier Safety Administration, U.S.DOT
LeRoy Gishi, Chief, Division of Transportation, Bureau of Indian Affairs, U.S. Department of the Interior, Washington, DC
Edward R. Hamberger, President and CEO, Association of American Railroads, Washington, DC
John C. Horsley, Executive Director, American Association of State Highway and Transportation Officials, Washington, DC
David T. Matsuda, Deputy Administrator, Maritime Administration, U.S.DOT
Victor M. Mendez, Administrator, Federal Highway Administration, U.S.DOT
William W. Millar, President, American Public Transportation Association, Washington, DC
Tara O'Toole, Under Secretary for Science and Technology, U.S. Department of Homeland Security, Washington, DC
Robert J. Papp (Adm., U.S. Coast Guard), Commandant, U.S. Coast Guard, U.S. Department of Homeland Security, Washington, DC
Cynthia L. Quarterman, Administrator, Pipeline and Hazardous Materials Safety Administration, U.S.DOT
Peter M. Rogoff, Administrator, Federal Transit Administration, U.S.DOT
David L. Strickland, Administrator, National Highway Traffic Safety Administration, U.S.DOT
Joseph C. Szabo, Administrator, Federal Railroad Administration, U.S.DOT
Polly Trottenberg, Assistant Secretary for Transportation Policy, U.S.DOT
Robert L. Van Antwerp (Lt. Gen., U.S. Army), Chief of Engineers and Commanding General, U.S. Army Corps of Engineers, Washington, DC
*Membership as of October 2010.
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NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM
NCHRP REPORT 681
Development of
a Precast Bent Cap System
for Seismic Regions
José I. Restrepo
UNIVERSITY OF CALIFORNIA, SAN DIEGO
La Jolla, CA
Matthew J. Tobolski
TOBOLSKI | WATKINS ENGINEERING, INC.
San Diego, CA
Eric E. Matsumoto
CALIFORNIA STATE UNIVERSITY, SACRAMENTO
Sacramento, CA
Subscriber Categories
Highways · Bridges and Other Structures
Research sponsored by the American Association of State Highway and Transportation Officials
in cooperation with the Federal Highway Administration
TRANSPORTATION RESEARCH BOARD
WASHINGTON, D.C.
2011
www.TRB.org
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NATIONAL COOPERATIVE HIGHWAY NCHRP REPORT 681
RESEARCH PROGRAM
Systematic, well-designed research provides the most effective Project 12-74
approach to the solution of many problems facing highway ISSN 0077-5614
administrators and engineers. Often, highway problems are of local ISBN 978-0-309-15533-5
interest and can best be studied by highway departments individually Library of Congress Control Number 2010943434
or in cooperation with their state universities and others. However, the © 2011 National Academy of Sciences. All rights reserved.
accelerating growth of highway transportation develops increasingly
complex problems of wide interest to highway authorities. These
problems are best studied through a coordinated program of COPYRIGHT INFORMATION
cooperative research.
Authors herein are responsible for the authenticity of their materials and for obtaining
In recognition of these needs, the highway administrators of the written permissions from publishers or persons who own the copyright to any previously
American Association of State Highway and Transportation Officials published or copyrighted material used herein.
initiated in 1962 an objective national highway research program Cooperative Research Programs (CRP) grants permission to reproduce material in this
employing modern scientific techniques. This program is supported on 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,
a continuing basis by funds from participating member states of the
FMCSA, FTA, or Transit Development Corporation endorsement of a particular product,
Association and it receives the full cooperation and support of the method, or practice. It is expected that those reproducing the material in this document for
Federal Highway Administration, United States Department of 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
Transportation.
from CRP.
The Transportation Research Board of the National Academies was
requested by the Association to administer the research program
because of the Board's recognized objectivity and understanding of
NOTICE
modern research practices. The Board is uniquely suited for this
purpose as it maintains an extensive committee structure from which The project that is the subject of this report was a part of the National Cooperative Highway
Research Program, conducted by the Transportation Research Board with the approval of
authorities on any highway transportation subject may be drawn; it the Governing Board of the National Research Council.
possesses avenues of communications and cooperation with federal,
The members of the technical panel selected to monitor this project and to review this
state and local governmental agencies, universities, and industry; its report were chosen for their special competencies and with regard for appropriate balance.
relationship to the National Research Council is an insurance of The report was reviewed by the technical panel and accepted for publication according to
procedures established and overseen by the Transportation Research Board and approved
objectivity; it maintains a full-time research correlation staff of
by the Governing Board of the National Research Council.
specialists in highway transportation matters to bring the findings of
The opinions and conclusions expressed or implied in this report are those of the
research directly to those who are in a position to use them. researchers who performed the research and are not necessarily those of the Transportation
The program is developed on the basis of research needs identified Research Board, the National Research Council, or the program sponsors.
by chief administrators of the highway and transportation departments The Transportation Research Board of the National Academies, the National Research
and by committees of AASHTO. Each year, specific areas of research Council, and the sponsors of the National Cooperative Highway Research Program do not
needs to be included in the program are proposed to the National endorse products or manufacturers. Trade or manufacturers' names appear herein solely
because they are considered essential to the object of the report.
Research Council and the Board by the American Association of State
Highway and Transportation Officials. Research projects to fulfill these
needs are defined by the Board, and qualified research agencies are
selected from those that have submitted proposals. Administration and
surveillance of research contracts are the responsibilities of the National
Research Council and the Transportation Research Board.
The needs for highway research are many, and the National
Cooperative Highway Research Program can make significant
contributions to the solution of 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 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 at:
http://www.national-academies.org/trb/bookstore
Printed in the United States of America
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COOPERATIVE RESEARCH PROGRAMS
CRP STAFF FOR NCHRP REPORT 681
Christopher W. Jenks, Director, Cooperative Research Programs
Crawford F. Jencks, Deputy Director, Cooperative Research Programs
Waseem Dekelbab, Senior Program Officer
Danna Powell, Senior Program Assistant
Eileen P. Delaney, Director of Publications
Ellen M. Chafee, Editor
NCHRP PROJECT 12-74 PANEL
Field of Design--Area of Bridges
Richard A. Pratt, Alaska DOT and Public Facilities, Juneau, AK (Chair)
Xiaohua Hannah Cheng, New Jersey DOT, Trenton, NJ
Carl J. Fuselier, Arkansas SHTD, Little Rock, AR
Jim Ma, California DOT, Sacramento, CA
Richard Marchione, New York State DOT, Albany, NY
Chuck Prussack, Central Pre-Mix Prestress Company, Spokane, WA
Holly Winston, Oregon DOT, Salem, OR
Lloyd M. Wolf, Texas DOT, Austin, TX
Derrell A. Manceaux, FHWA Liaison
Stephen F. Maher, TRB Liaison
AUTHOR ACKNOWLEDGMENTS
The research reported herein was performed under NCHRP Project 12-74 by the Department of Struc-
tural Engineering at the University of California, San Diego (UCSD). Dr. José I. Restrepo, Professor of
Structural Engineering at UCSD, was the Principal Investigator. Dr Eric E. Matsumoto, P.E., from Cali-
fornia State University, Sacramento (CSUS), was the Co-Principal Investigator. The other author of this
report is Dr. Matthew J. Tobolski, P.E., former graduate researcher at UCSD and current President of
Tobolski Watkins Engineering, Inc.
Other invaluable members of the research team include Mary Lou Ralls, P.E., of Ralls Newman, LLC;
Steve Mislinski, P.E., of LAN/AECOM; and Dr. M.J. Nigel Priestley and Jon Grafton of Pomeroy Corpo-
ration. Additionally, industry oversight was provided by Dr. Reid Castrodale, P.E., of Carolina Stalite; Bill
Spence, P.E., of Tidewater Skanska, Inc.; Lucian Bodgan, P.E., of Dywidag Systems International; Robert
Gulyas of BASF; Scott Harrigan, P.E., of The Fort Miller Co., Inc.; and Daniel Tassin, P.E., of International
Bridge Technologies. As a significant portion of this research relied on experimental testing, the excep-
tional efforts and dedication of the lab staff of both UCSD and CSUS must be acknowledged.
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FOREWORD
By Waseem Dekelbab
Staff Officer
Transportation Research Board
This report develops and validates precast concrete bent cap systems for use throughout
the nation's seismic regions. The report also includes a series of recommended updates to
the AASHTO LRFD Bridge Design Specifications, Guide Specification for LRFD Seismic Bridge
Design, and AASHTO LRFD Bridge Construction Specifications that will provide safe and
reliable seismic resistance in a cost-effective, durable, and constructible manner. The
material in this report will be of immediate interest to bridge engineers.
Precast bent cap systems are of increasing utility in highway construction. Precasting
moves concrete forming, pouring, and curing operations out of the work zone, making
bridge construction safer and more environmentally friendly, and it removes bent cap
construction from the critical path, thus accelerating the construction process. Precasting
also improves quality and durability because the work is performed in a more controlled
environment. The accelerated construction benefits of precast bent cap systems support the
philosophy of "get in, get out, stay out." Successful use of precast bent caps relies on proper
design, constructibility, and performance of the connections. Early uses of precast bent caps
were limited to applications where minimal moment and shear transfer were required at
connections. In seismic regions, provisions normally must be made to transfer greater forces
through connections.
The research was performed under NCHRP Project 12-74 by the University of California,
San Diego, with the assistance of California State University, Sacramento; Tobolski Watkins
Engineering, Inc.; and Ralls Newman, LLC. The research presented herein develops and
validates design methodologies, recommends design and construction specifications, and
provides design examples and example connection details for precast bent cap systems using
emulative and hybrid connections for integral and nonintegral systems for all seismic
regions throughout the United States.
A number of deliverables are provided as attachments to this report, including design
flow charts, design examples, example connection details, specimen drawings, specimen test
reports, and an implementation plan from the research agency's final report. These are not
published herein but are available on the TRB website at www.trb.org/Main/Blurbs/
164089.aspx. These attachments are titled as follows:
· Attachment DS--Design Specifications
· Attachment DE--Design Examples
· Attachment CS--Construction Specifications
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· Attachment ECD--Example Connection Details
· Attachment SD --Specimen Drawings
· Attachment TR--Test Reports
· Attachment CPT--Corrugated Pipe Thickness
· Attachment IP--NCHRP 12-74 Implementation Plan
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CONTENTS
1 Summary
5 Chapter 1 Introduction
5 1.1 Background
7 1.2 Implications for Bridge Design and Construction
7 1.3 Key Results from Initial Report
8 1.4 Summary of Experimental Specimens
9 Chapter 2 Findings
9 2.1 Introduction
9 2.2 Description of Experimental Test Program
33 2.3 Test Results
59 2.4 Analytical Results
62 Chapter 3 Interpretation, Appraisal, and Applications
62 3.1 Overview
62 3.2 Development of Design Specifications
82 3.3 Proposed Changes to AASHTO Guide Specifications for LRFD Seismic
Bridge Design and AASHTO LRFD Bridge Design Specifications
83 3.4 Design Flow Charts and Design Examples
84 3.5 Development of Construction Specifications
92 3.6 Proposed Changes to AASHTO LRFD Bridge
Construction Specifications
92 3.7 Example Connection Details
94 Chapter 4 Conclusions
94 4.1 Test Specimens
97 4.2 Design Specifications
99 4.3 Design Flow Charts and Design Examples
100 4.4 Construction Specifications
101 4.5 Example Connection Details
101 4.6 Implementation Plan
102 References
104 Unpublished Material
