Live load distribution of hybrid fiber-reinforced polymer composite superstructure on the basis of field test

Transverse live load distribution in a concrete-fiber-reinforced polymer (FRP) composite hybrid bridge was investigated both experimentally and analytically. The subject bridge was a concrete-FRP composite hybrid bridge, constructed with four 31-ft (9.4-m) long, prefabricated superstructure panels, which were joined along longitudinal field joints made of steel-reinforced grout. The live load distribution factors (DFs) of this bridge were evaluated with strain values measured in field tests and produced from finite element analysis. Design documents and load rating reports showed that a simplified method on the basis of beam-bending could be used in the design process, which required live load DFs. From strain values measured during load tests, the DFs were inferred to be 0.35 and 0.49 for interior and exterior panels, respectively. The comparison of load tests done 6 years apart indicated no significant change in the structural performance of the bridge. Although the design of this structure was unique, the evaluation showed that other hybrid structural members also could achieve good load distribution. The investigation indicated that composite structures could be durable with little maintenance required.