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South Dakota Department of Transportation
Project Synopsis
SD1992-13


Title: Evaluation of the Advanced Composite Bridge
Project Researcher: Len Moser,
Project Manager:
Research Period: -
Status:
Cost: $0.00

Problem Statement:Reinforcing steel in highway structures is susceptible to corrosion from exposure to deicing chemicals. For the past 15-20 years, SDDOT and other agencies have used epoxy-coated steel to prevent corrosion. Epoxy-coated steel appears to prevent corrosion successfully, but its performance over very long time periods has not been established. If epoxy-coated steel demonstrates long-term performance problems, alternative materials would be needed.

Because non-metallic fibers may resist chemical attack, they could potentially replace steel as a reinforcing material. Fiber/epoxy composites also demonstrate some advantages over steel in prestressing applications. Most notably, prestressing losses with fiberglass or graphite fibers are less than for steel. More general use of prestressing (with any material) could help eliminate cracking in concrete bridge decks.

Lack of critical knowledge prevents widespread application of composite technology in structures. Not enough is known about the materials behavior under load. Unlike steel, which can withstand large plastic deformation when overstressed, fibers break suddenly; larger safety factors may therefore be required to ensure structural integrity. Design guidelines are not yet available, and recommended construction practices have not been determined. Without this information, engineers are unable to use composite technology for highway structures.

Findings:

Research Objectives:
1  To evaluate the feasibility of building a bridge incorporating a concrete deck prestressed with fiberglass and graphite composites, considering material specifications and handling, safety, inspection requirements, and special equipment and labor nee
2  To evaluate and compare the structural performance, including response to overload and ultimate strength in bending and shear, of composites and steel in a prestressed concrete bridge deck;
3  To develop guidelines for future design, construction and monitoring of prestressed concrete bridge decks.

Research Tasks:
1  Review literature pertinent to the use of fiber/epoxy composites in highway structures.
2  Design and construct a test bridge with deck sections individually prestressed with steel, fiberglass and graphite tendons.
3  Monitor structural performance of the test bridge under service loads for at least one year. If significant changes in structural performance are evident, the monitoring period could be extended.
4  Prepare and submit an interim report describing the bridge design, materials specifications, construction history, and structural performance under service loads.
5  Load the test bridge to induce failure (cable slippage, cable fracture or compressive failure of concrete) each bridge deck section under shear and moment.
6  Analyze the induced bridge failure to determine failure mode and corresponding load for each deck section, compare performance of prestressing materials, and compare actual performance to theoretical predictions.
7  Develop guidelines for design, construction and monitoring of prestressed concrete structures.
8  Prepare and submit a final report summarizing the literature search, research methodology, performance data, findings, conclusions and recommendations.
9  Present a summary of research and findings to SDDOT's Research Review Board.

Documents Available:

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