This paper presents numerical analyses of reinforced concrete beams subjected to axial compression. A rigid-bodyspring model is used to represent concrete material as an assemblage of rigid particles interconnected along their boundaries through flexible interfaces. The material is discretized into a large number of random particles using Voronoi diagrams in order to reduce mesh bias on the fracture conditions. Rather than averaging the effect of reinforcing over a regional material volume, reinforcing material is explicitly modeled. Mesh construction is greatly facilitated since the material discretization is semiautomated and each reinforcement can be positioned irrespective of the concrete material. Numerical results agree well with experimental observations in terms of loading capacity, crack patterns, concrete strain, and steel strain. The model predicts an increase of shear carrying capacity in RC beams due to axial compression. The rate of increase of shear carrying capacity is investigated through analyses of RC beams with the different span-depth ratio.
