Um Modelo Microscópico para a Fratura do Concreto Simples

Abstract

Fracture of quasi-brittle materials, such as plain concrete, normally occurs at the planes of maximal tension stresses. However, due to microscopic heterogeneity of the concrete, crack path tends to follow the boundary of the aggregates, so a purely stress based criteria for crack propagation can be seen as a macroscopic simplification. In this work, the presence of aggregates is discretely considered. Crack path is constrained to aggregate boundaries using cohesive surfaces between finite elements. The cohesive model used is able to deal with shear stresses that occur at the propagation planes. In the proposed model, the finite element meshes should represent, approximately, the distribution of aggregates. The meshes are actually defined randomly by a non-structured mesh generator, so results obtained in this work also present some degree of randomness typically found in the concrete fracture. A good agreement was obtained with experiments.