Shear-Fatigue Behaviour of RC Cantilever Bridge Deck Slabs under Concentrated Loads

Shear has been observed to be the governing failure mode of RC cantilever deck slabs of bridges without shear reinforcement when subjected to concentrated loads of heavy vehicles. This observation has been verified experimentally for a quasi-static application of the load. However, concentrated loads have a repetitive nature, causing loss of stiffness and potential strength reductions due to fatigue phenomena. In this paper, the fatigue behaviour of cantilever bridge deck slabs is investigated. A specific experimental programme consisting on eleven tests under concentrated fatigue loads and four static tests (reference specimens) is presented. The results show that cantilever bridge deck slabs are significantly less sensitive to shear-fatigue failures than beams without shear reinforcement. Slabs that failed due to rebar fractures presented significant remaining life after first rebar failure occurred. The test results are presented and finally compared to the shear-fatigue provisions of the fib-Model Code 2010.