Design and field evaluation of a hybrid FRP composite - Lightweight concrete road bridge

The innovative hybrid idea of a FRP composite - lightweight concrete structural system for vehicular bridges has been proposed. Due to the lack of commonly accepted design procedures, the whole designing process was based on FEA and strongly supported by testing. Also, the result - a demonstrative vehicular bridge - was the subject of investigation focused on evaluating the bridge performance under proof load. A prototype hybrid structure with the span length of 21.0 m was subjected to a series of static and dynamic loading tests. The results obtained from the investigation were used to verify the applied design procedure by determining the key behaviour characteristics: stiffness, strength, load transverse distribution, degree of composite action, and dynamic performance and comparing them with design predictions. Linear FEA was found to predict accurately the flexural behaviour of hybrid bridge systems in the elastic range. With respect to the static and dynamic performance, the novel hybrid bridge system fully conformed to design requirements of relevant standards. However, the field test results indicated that the design assumptions seem to be conservative because a significant margin of safety was revealed, particularly in terms of FRP strength. Therefore, some implications of field evaluation results for future designs of hybrid FRP-concrete bridges have been presented in the paper.