Experimental and analytical investigation of flexural behaviour of UHPFRC retrofitted bridge deck and barrier under vehicular impact

The steady increase in the weight of vehicle on the highway poses growing challenges to bridge safety. This article is concerned with strengthening the cantilevered deck slab adjacent to vehicular barriers by placing a membrane made of ultra-high performance fibre reinforced concrete (UHPFRC) for countering flexural demand at the fixed end of the cantilever caused by vehicular impact combined with gravitational loads. In this study, the overlay was found from impact tests to be highly effective in widely distributing an impact action transmitted from the point of contact on the barrier to the adjoining slab. The moment of resistance of the slab is also enhanced significantly by composite action between the overlay and the concrete substrate. Attributed to the dual enhancement mechanism, the overload ratio of the UHPFRC retrofitted cantilevered slab (defined herein as the flexural resistant capacity of a unit length of the slab divided by the demand of the combined action) is approximately double of that of the conventional concrete slab for the same impact scenario.