MESO-SCALE SIMULATIONS ON FLEXURAL FAILURE AND SIZE EFFECT OF REINFORCED CONCRETE BEAMS

The sources of size effect on RC members are the heterogeneity of concrete material and the interaction between steel and concrete. From the view of microcosmic, a three-dimensional micromechanical model for reinforced concrete beams was set up. In the model, the concrete heterogeneity was considered, and the interactions between steel and concrete was described by a nonlinear spring element. Base on the well agreement between simulation results and experimental results, the failure behavior of large beams was studied, meanwhile, the change of failure pattern and flexural strength of different size beams under monotonic and cyclic loading were analyzed. The simulation results show that:1) in the working condition of this article, the flexural of RC cantilever beams have the size effect, and the flexural strength decreases with the increase of depth of the beam; 2) under cyclic loading, the bending beam is brittle because of the fatigue of the bonding performance between concrete and steel; 3) compared to monotonic loading, the cantilever beam damage is more brittle and the size effect of nominal flexural strength is more obvious under a cyclic loading condition.