Insights on crack initiation and propagation in reinforced concrete beams, a bonded-particle approach

Failure mechanism of reinforced concrete beams without stirrups is a topic of interest to the structural mechanics researchers. The lessons learned from the investigation on the interaction of the reinforcement with the host medium is important to the rock engineers as well. In this paper, a new discrete element based numerical approach is proposed to model reinforced concrete and bolted rock structures. In this approach, the reinforcement is represented explicitly by the cable structural elements and the host medium is simulated with a bondedparticle model in which the discrete particles are circular in shape. The nodes of the cable elements are allowed to interact with the discrete particles using some elastic perfectly plastic springs to simulate the grout material between the host medium and the reinforcement elements. The micro-mechanical concept of the model is described in details. Some four-point bending experiments are numerically conducted on reinforced concrete beams without stirrups to validate the model. The numerical results show that the proposed model is able to capture the flexural crack pattern, diagonal shear-induced tensile cracks, and shear capacity of the beams. The numerical results are discussed and carefully compared with some published data in the literature.