Effect of tensile softening relation on size effect of concrete in bending

摘要

In the current paper, the effect of tensile softening parameters, the tensile strength σ_t and the initial slope k_1 of the stress-crack width curve, on the structural size-effect law in bending of concrete are studied by a bending model. The model results show that the size-effect law in bending strength normally presented by flexural strength and beam height diagram (σ_f-logH) is strongly dependent on σ_t and k_1. With increase of beam height, the general size-effect law in bending can be characterised as a fast reduction stage followed by a stable decreasing stage and finally converged to the tensile strength of concrete. With increasing tensile strength, the σ_f-logH curve goes up and the value of dσ_f/dlogH gradually increases. In the meantime, for a given beam height, bending strength increases with increase of k_1. The model predictions are compared with experimental results. Good agreement between model predictions and experiments has been obtained.