A multiphase mesostructure mechanics approach to the study of the fracture-damage behavior of concrete

A multiphase mesostructure mechanical model is proposed to study the deformation and failure process of concrete considering its heterogeneity at the meso scopic level. Herein, concrete is taken as a type of three-component composite material composed of mortar matrix, aggregates and interfaces on the meso-scale. First, an efficient approach to the disposition of aggregates of concrete and a state matrix method to generate mesh coordinates for aggregates are proposed. Secondly, based on the nonlinear continuum damage mechanics, a meso-scale finite element model is presented with damage softening stress-strain relationship for describing the mechanical behavior of different components of concrete. In this method, heterogeneities of each component in the concrete are considered by assuming the material properties of three components conform to the Welbull distribution law. Finally, based on this multiphase meso-mechanics model, a simulation analysis of fracture behavior of a rock-fill concrete (RFC) beam is accomplished. The study includes experimental tests for determining basic mechanical parameters of three components of RFC and four-point flexural beam tests for verification of the model. It is preliminarily shown that the numerical model is applicable to studying failure mechanisms and process of concrete type material.