Prestressed Concrete Bridge Girder Design Examples

362 Pages·2006·1.99 MB·English

by  Texas Transportation Institute

Technical Report Documentation Page
1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FHWA/TX-06/0-4751-1 Vol. 2

4. Title and Subtitle 5. Report Date
IMPACT OF LRFD SPECIFICATIONS ON DESIGN OF TEXAS BRIDGES May 2006
VOLUME 2: PRESTRESSED CONCRETE BRIDGE GIRDER DESIGN Published: December 2006
EXAMPLES

6. Performing Organization Code

7. Author(s) 8. Performing Organization Report No.
Mary Beth D. Hueste, Mohammed Safi Uddin Adil, Mohsin Adnan, and Peter B. Report 0-4751-1
Keating

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
Texas Transportation Institute

The Texas A&M University System
11. Contract or Grant No.
College Station, Texas 77843-3135
P roject 0-4751
12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered
Texas Department of Transportation Technical Report:
Research and Technology Implementation Office September 2003-August 2005

P. O. Box 5080
14. Sponsoring Agency Code
A ustin, Texas 78763-5080

15. Supplementary Notes
Project performed in cooperation with the Texas Department of Transportation and the Federal Highway Administration.
Project Title: Impact of LRFD Specifications on the Design of Texas Bridges
URL: http://tti.tamu.edu/documents/0-4751-1-V2.pdf

16. Abstract
The Texas Department of Transportation (TxDOT) is currently designing highway bridge structures using the American
Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Highway Bridges, and it is
expected that the agency will transition to the use of the AASHTO LRFD Bridge Design Specifications before 2007. This is a
two-volume report that documents the findings of a TxDOT-sponsored research project to evaluate the impact of the Load and
Resistance Factor (LRFD) Specifications on the design of typical Texas bridges as compared to the Standard Specifications. The
objectives of this portion of the project are to evaluate the current LRFD Specifications to assess the calibration of the code with
respect to typical Texas prestressed bridge girders, to perform a critical review of the major changes when transitioning to LRFD
design, and to recommend guidelines to assist TxDOT in implementing the LRFD Specifications.

A parametric study for AASHTO Type IV, Type C, and Texas U54 girders was conducted using span length, girder spacing, and
strand diameter as the major parameters that are varied. Based on the results obtained from the parametric study, two critical areas
were identified where significant changes in design results were observed when comparing Standard and LRFD designs. The
critical areas are the transverse shear requirements and interface shear requirements, and these are further investigated. In
addition, limitations in the LRFD Specifications, such as those for the percentage of debonded strands and use of the LRFD live
load distribution factor formulas, were identified as restrictions that would impact TxDOT bridge girder designs, and these issues
are further assessed. The results of the parametric study, along with critical design issues that were identified and related
recommendations, are summarized in Volume 1 of this report. Detailed design examples for an AASHTO Type IV girder and a
Texas U54 girder using both the AASHTO Standard Specifications and AASHTO LRFD Specifications were also developed and
compared. Volume 2 of this report contains these examples.

17. Key Words 18. Distribution Statement
Prestressed Concrete, LRFD, Design, Bridge Girders, U54 No restrictions. This document is available to the public
Girder, Type IV Girder, Type C Girder, Parametric Study through NTIS:
National Technical Information Service
Springfield, Virginia 22161
http://www.ntis.gov

19. Security Classif.(of this report) 20. Security Classif.(of this page) 21. No. of Pages 22. Price
Unclassified Unclassified 362
Form DOT F 1700.7
(8-72) Reproduction of completed page authorized

IMPACT OF LRFD SPECIFICATIONS ON DESIGN OF TEXAS BRIDGES
VOLUME 2: PRESTRESSED CONCRETE BRIDGE GIRDER DESIGN
EXAMPLES

by

Mary Beth D. Hueste, P.E.
Associate Research Engineer
Texas Transportation Institute

Mohammed Safi Uddin Adil
Graduate Research Assistant
Texas Transportation Institute

Mohsin Adnan
Graduate Research Assistant
Texas Transportation Institute

and

Peter B. Keating
Associate Research Engineer
Texas Transportation Institute

Report 0-4751-1
Project Number 0-4751
Project Title: Impact of LRFD Specifications on Texas Bridges

Performed in Cooperation with the
Texas Department of Transportation
and the
Federal Highway Administration

May 2006
Published: December 2006

TEXAS TRANSPORTATION INSTITUTE
The Texas A&M University System
College Station, Texas 77843-3135

DISCLAIMER

The contents of this report reflect the views of the authors, who are responsible for the
facts and the accuracy of the data presented herein. The contents do not necessarily reflect the
official view or policies of the Federal Highway Administration (FHWA) or the Texas
Department of Transportation (TxDOT). While every effort has been made to ensure the
accuracy of the information provided in this report, this material is not intended to be a substitute
for the actual codes and specifications for the design of prestressed bridge girders. This report
does not constitute a standard, specification, or regulation; and is not intended for constructing,
bidding, or permit purposes. The engineer in charge was Mary Beth D. Hueste, P.E. (TX
89660).

v
ACKNOWLEDGMENTS

This research was conducted at Texas A&M University (TAMU) and was supported by
TxDOT and FHWA through the Texas Transportation Institute (TTI) as part of Project 0-4751,
“Impact of LRFD Specifications on Design of Texas Bridges.” The authors are grateful to the
individuals who were involved with this project and provided invaluable assistance, including
Rachel Ruperto (TxDOT, Research Project Director), David Hohmann (Research Project
Coordinator), Gregg Freeby (TxDOT), John Holt (TxDOT), Mark Steves (TxDOT), John Vogel
(TxDOT), and Dennis Mertz (University of Delaware). Special thanks go to Richard Gehle
(TAMU), who provided valuable assistance in the final formatting of this report.

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TABLE OF CONTENTS

Page

Appendix A.1: Design Example for Interior AASHTO Type IV Girder using
AASHTO Standard Specifications ............................................................A.1-i

Appendix A.2: Design Example for Interior AASHTO Type IV Girder using
AASHTO LRFD Specifications..................................................................A.2-i

Appendix B.1: Design Example for Interior Texas U54 Girder using AASHTO
Standard Specifications...............................................................................B.1-i

Appendix B.2: Design Example for Interior Texas U54 Girder using AASHTO
LRFD Specifications....................................................................................B.2-i

vi i

Appendix A.1

Design Example for Interior AASHTO Type IV
Girder using AASHTO Standard Specifications

A.1 - i