Influence of aggregate bridging on the fatigue behavior of concrete

•Expression for bridging stress is proposed from macroscopic and mesoscopic properties.•The effect of the size of specimen and the stress ratio on the bridging stress is studied.•Fatigue crack propagation model for concrete is obtained by including the bridging stress.•Residual moment capacity of concrete beams at different stress ratios is studied.

The fracture process of concrete is characterized by various toughening mechanisms that exist at the macro crack tip. In this study, the crack growth resistance due to the bridging of aggregates (defined as bridging stress) is evaluated by relating the crack opening displacements at the macroscopic scale to the mesoscopic one by considering the fracture toughness and the elastic modulus of the interface between the coarse aggregate and the mortar. The influence of specimen size and the stress ratio on the bridging stress is studied. The effect of the bridging stress on the fatigue crack growth rate is predicted and the results are found to agree well with the experiments for normal and micro concrete. The residual strength of a damaged beam is computed in terms of the moment carrying capacity by considering the bridging resistance offered by the coarse aggregates.