Mesomechanical model for concrete. Part I: Model development

A damage mechanics-based numerical model for simulating the fracture process of concrete is presented. The model is based on knowledge of heterogeneity of concrete at the meso-level, in which the concrete is assumed to be a three-phase composite made up of the cement matrix phase, the aggregate phase and the matrix-aggregate interface phase. The constitutive law of each phase is defined on the basis of elastic damage mechanics, the finite element method is employed as the basic stress analysis tool, and the maximum tensile strain criterion and the Mohr-Coulomb criterion are adopted as damage thresholds. A simple method analogous to the smeared crack method is used for tracing the crack propagation process and for capturing the interaction of multiple cracks. Based on this model, a numerical simulation program, named Concrete Fracture Process Analysis (CFPA), was developed. The influences of various parameters of the model on its performance, including the Weibull distribution parameters, constitutive parameters and the number of elements are discussed in detail. Issues in the realistic simulation of concrete behaviour are also examined. Results from numerical simulations of concrete specimens under a variety of loading conditions using CFPA are presented in the companion paper.