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COMPREHENSIVE DESIGN EXAMPLE FOR PRESTRESSED
CONCRETE (PSC) GIRDER SUPERSTRUCTURE BRIDGE
WITH COMMENTARY
(Task order DTFH61-02-T-63032)
US CUSTOMARY UNITS
Submitted to
THE FEDERAL HIGHWAY ADMINISTRATION
Prepared By
Modjeski and Masters, Inc.
November 2003 Technical Report Documentation Page
1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No.
FHWA NHI - 04-043
4. Title and Subtitle 5. Report Date
Comprehensive Design Example for Prestressed Concrete (PSC) November 2003
Girder Superstructure Bridge with Commentary 6. Performing Organization Code
(in US Customary Units)
7. Author (s) Wagdy G. Wassef, Ph.D., P.E., Christopher Smith, E.I.T. 8. Performing Organization Report No.
Chad M. Clancy, P.E., Martin J. Smith, P.E.
9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
Modjeski and Masters, Inc.
11. Contract or Grant No. P.O.Box 2345
Harrisburg, Pennsylvania 17105 DTFH61-02-D-63006
12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered
Federal Highway Administration Final Submission
National Highway Institute (HNHI-10) August 2002 – November 2003
14. Sponsoring Agency Code 4600 N. Fairfax Drive, Suite 800
Arlington, Virginia 22203
15. Supplementary Notes
Modjeski and Masters Principle Investigator and Project Manager :
Wagdy G. Wassef , Ph.D., P.E.
FHWA Contracting Officer’s Technical Representative: Thomas K. Saad, P.E.
Team Leader, Technical Review Team: Jerry Potter, P.E.
16. Abstract
This document consists of a comprehensive design example of a prestressed concrete girder bridge. The superstructure
consists of two simple spans made continuous for live loads. The substructure consists of integral end abutments and a
multi-column intermediate bent. The document also includes instructional commentary based on the AASHTO-LRFD
Bridge Design Specifications (Second Edition, 1998, including interims for 1999 through 2002). The design example and
commentary are intended to serve as a guide to aid bridge design engineers with the implementation of the AASHTO-
LRFD Bridge Design Specifications. This document is offered in US Customary Units. An accompanying document in
Standard International (SI) Units is offered under report No. FHWA NHI-04-044.
This document includes detailed flowcharts outlining the design steps for all components of the bridge. The flowcharts
are cross-referenced to the relevant specification articles to allow easy navigation of the specifications. Detailed design
computations for the following components are included: concrete deck, prestressed concrete I-girders, elastomeric
bearing, integral abutments and wing walls, multi-column bent and pile and spread footing foundations.
In addition to explaining the design steps of the design example, the comprehensive commentary goes beyond the
specifics of the design example to offer guidance on different situations that may be encountered in other bridges.
17. Key Words 18. Distribution Statement
Bridge Design, Prestressed Concrete, Load and Resistance This report is available to the public from the
Factor Design, LRFD, Concrete Deck, Intermediate Bent, National Technical Information Service in
Integral Abutment, Wingwall, Pile Foundation, Spread Springfield, Virginia 22161 and from the
Footings Superintendent of Documents, U.S. Government
Printing Office, Washington, D.C. 20402.
19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price
Unclassified Unclassified 381
Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
This page intentionally left blank
ACKNOWLEDGEMENTS
The authors would like to express appreciation to the review teams from the Illinois Department of Transportation,
Minnesota Department of Transportation and Washington State Department of Transportation for providing review and
direction on the Technical Review Committee.
The authors would also like to acknowledge the contributions of Dr. John M. Kulicki, President/CEO and Chief
Engineer of Modjeski and Masters, Inc., for his guidance throughout the project. Table of Contents Prestressed Concrete Bridge Design Example
TABLE OF CONTENTS
Page
1. INTRODUCTION .........................................................................................................1-1
2. EXAMPLE BRIDGE ....................................................................................................2-1
2.1 Bridge geometry and materials.............................................................................2-1
2.2 Girder geometry and section properties ...............................................................2-4
2.3 Effective flange width ........................................................................................2-10
3. FLOWCHARTS ............................................................................................................3-1
4. DESIGN OF DECK .......................................................................................................4-1
5. DESIGN OF SUPERSTRUCTURE
5.1 Live load distribution factors ..............................................................................5-1
5.2 Dead load calculations.......................................................................................5-10
5.3 Unfactored and factored load effects.................................................................5-13
5.4 Loss of prestress ...............................................................................................5-27
5.5 Stress in prestressing strands.............................................................................5-36
5.6 Design for flexure
5.6.1 Flexural stress at transfer ......................................................................5-46
5.6.2 Final flexural stress under Service I limit state ....................................5-49
5.6.3 Longitudinal steel at top of girder.........................................................5-61
5.6.4 Flexural resistance at the strength limit state in positive
moment region .....................................................................................5-63
5.6.5 Continuity correction at intermediate support ......................................5-67
5.6.6 Fatigue in prestressed steel ...................................................................5-75
5.6.7 Camber..................................................................................................5-75
5.6.8 Optional live load deflection check ......................................................5-80
5.7 Design for shear ................................................................................................5-82
5.7.1 Critical section for shear near the end support......................................5-84
5.7.2 Shear analysis for a section in the positive moment region..................5-85
5.7.3 Shear analysis for sections in the negative mome5-93
5.7.4 Factored bursting resistance................................................................5-101
5.7.5 Confinement reinforcement5-102
5.7.6 Force in the longitudinal reinforcement including the effect of
the applied shear .................................................................................5-104
6. DESIGN OF BEARINGS .............................................................................................6-1
Task Order DTFH61-02-T-63032 i Table of Contents Prestressed Concrete Bridge Design Example
7. DESIGN OF SUBSTRUCTURE ..................................................................................7-1
7.1. Design of Integral Abutments
7.1.1 Gravity loads...........................................................................................7-6
7.1.2 Pile cap design .....................................................................................7-11
7.1.3 Piles.......................................................................................................7-12
7.1.4 Backwall design....................................................................................7-16
7.1.5 Wingwall design ...................................................................................7-30
7.1.6 Design of approach slab........................................................................7-34
7.1.7 Sl