ABSTRACT
This paper describes the design and construction of an all-composite bridge (Bridge 351 on N387A over Muddy Run) in Delaware. The construction consisted of substructure rehabilitation and replacement of the superstructure using fiber-reinforced polymer (FRP) materials. Since the behavior of these materials is not yet fully understood by bridge engineers, the Delaware Department of Transportation (DelDOT) and the Federal Highway Administration (FHWA) collaborated with the University of Delaware (UD) to develop design methods and construction techniques. Extensive coupon testing, coupled with knowledge from existing literature regarding material durability, resulted in the development of reduction factors appropriate for use in design. The design of the FRP structures was based upon guidelines given in the American Association of State Highway and Transportation Official (AASHTO) Load and Resistance Factor Design (LRFD) specifications. The overall structural behavior was accurately predicted using simple design equations based on sandwich theory for anisotropic materials. To prove that the design satisfied deflection, fatigue, and strength limit states, large-scale testing of full-size sub-components was conducted. UD performed full-scale proof testing of the final FRP superstructure prior to erection. The structure was also monitored during construction. The testing demonstrated that the FRP structural performance was conservative with respect to design parameters and that it matched the expected behavior within 10%. The construction was successfully completed and the bridge opened to traffic on November 20, 1998.
