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Publication Number: FHWA-HRT-05-058
Date: October 2006

Optimized Sections for High-Strength Concrete Bridge Girders--Effect of Deck Concrete Strength

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FOREWORD

For more than 25 years, concretes with compressive strengths in excess of 41 megapascals (MPa) (6,000 pounds per square inch (psi)) have been used in the construction of columns of highrise buildings. While the availability of high-strength concretes was limited initially to a few geographic locations, opportunities to use these concretes at more locations across the United States have arisen. Although the technology to produce higher-strength concretes has developed primarily within the ready-mix concrete industry for use in buildings, the same technology can be applied in the use of concretes for bridge girders and bridge decks.

The durability of concrete bridge decks has been a concern for many years, and numerous strategies to improve the performance of bridge decks have been undertaken.Many of the factors that enable a durable concrete to be produced also result in a high-strength concrete. Consequently, if a concrete for a bridge deck to be durable, it will probably also have a high compressive strength.This report contains an evaluation of the effect of high-performance concrete on the cost and structural performance of bridges constructed with high-performance concrete bridge decks and high-strength concrete girders. Several areas with the potential for improved structural performance through the use of high-performance concretes are investigated. This report should also assist designers and owners in recognizing that the use of high-performance concrete in bridges has advantages beyond those of improving durability.

Gary Henderson

Director, Office of Infrastructure

Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

Technical Report Documentation Page

1. Report No.

FHWA-HRT-05-058

2. Government Accession No. 3 Recipient's Catalog No.
4. Title and Subtitle

Optimized Sections for High-Strength Concrete Bridge Girders–Effect of Deck Concrete Strength

5. Report Date

October 2006

6. Performing Organization Code
7. Author(s)

Turner-Fairbank Highway Research Center

8. Performing Organization Report No.

 

9. Performing Organization Name and Address

Office of Research, Development, and Technology
Turner-Fairbank Highway Research Center
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

DTFH

12. Sponsoring Agency Name and Address

Office of Research, Development, and Technology
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101

13. Type of Report and Period Covered

Evaluation, 1995–1997

14. Sponsoring Agency Code

 

15. Supplementary Notes

Contracting Officer's Technical Representative: Joseph L. Hartmann, HRDI-06

16. Abstract

This report contains an evaluation of the effect of high-performance concrete on the cost and structural performance of bridges constructed with high-performance concrete bridge decks and high-strength concrete girders. Bridge designers and owners are the main audience.

17. Key Words

High-Performance Concrete, Girders, Concrete Bridge Decks

18. Distribution Statement

No restrictions. This document is available to the

Public through the National Technical Information Service; Springfield, VA 22161

19. Security Classification
(of this report)

Unclassified

20. Security Classification
(of this page)

Unclassified

21. No. of Pages

93

22. Price
Form DOT F 1700.7 Reproduction of completed page authorized

SI (Modern Metric) Conversion Factors

PREFACE

For over 25 years, concretes with specified compressive strengths in excess of 41 MPa (6,000 psi) have been used in the construction of columns of highbrows. While the availability of the high-strength concretes was limited initially to a few geographic locations, opportunities have developed to use these concretes at more locations across the United States. As these opportunities have developed,material producers and contractors have accepted the challenge to produce concretes with higher compressive strengths.

In the precast, prestressed concrete bridge field, a specified compressive strength of 41 MPa (6,000 psi) for bridge girders has been used for many years. However,strengths at release have often controlled the concrete mix design so that actual strengths at 28 days were often in excess of 41 MPa (6,000 psi). It is only in recent years that a strong interest in the utilization of concrete with higher compressive strengths has emerged. This interest has developed at a few geographic locations for specific projects in a manner similar to the development in the building industry.

In parallel with an increased interest in the use of high-strength concretes in bridge girders,the use of high-performance concretes in bridge decks has also been receiving increased attention as a means of improving durability. High-performance concretes provide higher resistance to chloride penetration, higher resistance to deicer scaling, less damage from freezing and thawing, higher wear resistance, and less cracking. Many of the methods used to increase the durability of concrete result in a concrete that has a higher compressive strength. However, the higher concrete strength is rarely considered because the design of prestressed girders is controlled by service load stresses caused by dead load, live load, and impact.

This report contains an evaluation of the effect of high-performance concrete on the cost and structural performance of bridges constructed with high-performance concrete bridge decks and high-strength concrete girders. Several areas with the potential for improved structural performance through the use of high-performance concretes are investigated. This report should assist designers and owners in recognizing that the use of high-performance concrete in bridges has advantages beyond those of improving durability.

The research described in this report was sponsored by the Federal Highway Administration as part of their program to encourage the greater use of high-performance concretes in bridges. The program includes analytical and experimental research as well as showcase projects. The authors believe that high-performance concrete represents a technology with great potential for improving the infrastructure of the highway system.

Table of Contents

CHAPTER 1. INTRODUCTION

BACKGROUND

OPTIMIZED CROSS SECTIONS FOR BRIDGE GIRDERS

HIGH-PERFORMANCE CONCRETE IN BRIDGE DECKS

EFFECT OF HIGH-STRENGTH CONCRETE ON PRESTRESS LOSSES

OBJECTIVES AND SCOPE

CHAPTER 2. TASK 1: COST ANALYSES OF HIGH-PERFORMANCE CONCRETE IN BRIDGE DECKS

RESEARCH APPROACH

EFFECTS OF CONCRETE STRENGTH ONLY

EFFECTS OF CONCRETE COSTS

TASK 1 CONCLUSIONS

CHAPTER 3. TASK 2: ANALYSES OF FLEXURAL STRENGTH AND DUCTILITY

RESEARCH APPROACH

MATERIAL PROPERTIES

MOMENT-CURVATURE RELATIONSHIPS

FLEXURAL STRENGTH

TASK 2 CONCLUSIONS

CHAPTER 4. TASK 3: ANALYSES OF PRESTRESS LOSSES AND LONG-TERM DEFLECTIONS

RESEARCH APPROACH

MATERIAL PROPERTIES

PRESTRESS LOSSES

LONG-TERM DEFLECTIONS

TASK 3 CONCLUSIONS

CHAPTER 5. CONCLUSIONS AND RECOMMENDATIONS

CONCLUSIONS

RECOMMENDATIONS

ACKNOWLEDGMENTS

REFERENCES

List of Figures

Figure 1. Cross section of girder analyzed—PCI Bulb-Tee (BT-72). All dimensions are in millimeters (inches).

Figure 2. Cross section of girder analyzed—Florida Bulb-Tee (FL BT-72). All dimensions are in millimeters (inches)..

Figure 3. Cost chart for a BT-72, 41 MPa.

Figure 4. Optimum cost curves for a BT-72, 41 MPa.

Figure 5. Optimum cost curves for a BT-72, 83 MPa.

Figure 6. Optimum cost curves for a BT-72, 55 MPa.

Figure 7. Optimum cost curves for a BT-72, 69 MPa.

Figure 8. Comparison of optimum cost curves for a BT-72 with varying concrete strengths.

Figure 9. Comparison of optimum cost curves for a FL BT-72 with varying concrete strengths.

Figure 10. Optimum cost curves for a BT-72, 41 MPa with cost premium.

Figure 11. Optimum cost curves for a BT-72, 55 MPa with cost premium.

Figure 12. Optimum cost curves for a BT-72, 69 MPa with cost premium.

Figure 13. Optimum cost curves for a BT-72, 83 MPa with cost premium.

Figure 14. Optimum cost curves for a FL BT-72, 41 MPa with cost premium.

Figure 15. Optimum cost curves for a FL BT-72, 83 MPa with cost premium.

Figure 16 (part 1). Cross section of series A girder (BT-72) analyzed in task 2. All dimensions are in millimeters (inches).

Figure 16 (part 2). Cross section of series B girder (BT-72) analyzed in task 2. All dimensions are in millimeters (inches).

Figure 16 (part 3). Cross section of series C girder (BT-72) analyzed in task 2. All dimensions are in millimeters (inches).

Figure 16 (part 4). Cross section of series D girder (BT-72) analyzed in task 2. All dimensions are in millimeters (inches).

Figure 17. Stress–strain curves for concrete used in BEAM BUSTER analysis.

Figure 18. Stress–strain curve for prestressing strand used in BEAM BUSTER analysis.

Figure 19. Moment–curvature relationships for BT-72, 41 MPa at a span of 24.4 m.

Figure 20. Moment-curvature relationships for BT-72, 83 MPa at a span of 24.4 m.

Figure 21. Moment-curvature relationships for BT-72, 41 MPa at a span of 44.5 m.

Figure 22. Moment-curvature relationships for BT-72, 83 MPa at a span of 53.3 m.

Figure 23 (part 1). Cross section of series A through D girders (BT-72) analyzed in task 3. All dimensions are in millimeters (inches).

Figure 23 (part 2). Cross section of series E girder (BT-72), 24.4 m (80-ft) span, analyzed in task 3. All dimensions are in millimeters (inches).

Figure 23 (part 3). Cross section of series E girder (BT-72), 44.5 m (146-ft) span, analyzed in task 3. All dimensions are in millimeters (inches).

Figure 23 (part 4). Cross section of series E girder (BT-72), 53.3 m (175-ft) span, analyzed in task 3. All dimensions are in millimeters (inches).

Figure 24. Variation of specific creep with compressive strength as published.

Figure 25. Variation of ultimate specific creep with compressive strength.

Figure 26. Variation of specific creep with age.

Figure 27. Prestressing strand stress versus time for varying girder concrete strength, 28-MPa deck strength, and 44.5-m span.

Figure 28. Prestressing strand stress versus time for 83-MPa girder concrete strength, 55-MPa deck strength, and varying spans.

Figure 29. Midspan deflection versus time for varying girder concrete strengths, 28-MPa deck strength, and 44.5-m span.

Figure 30. Midspan deflection versus time for 41-MPa girder concrete strength, varying deck concrete strengths, and 44.5-m span.

Figure 31. Midspan deflection versus time for 83-MPa girder concrete strength, 55-MPa deck strength, and varying spans.

List of Tables

 

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