Numerical evaluation of aggregate size influence on concrete mechanical damage under high temperatures

Abstract

The influence of aggregate size on the degradation process of material exposed to high temperatures is not a consensus among the scientific community because changes in the microstructure impact the macrostructural performance. To contribute to this investigation this work presents a thermomechanical model to evaluate aggregate size influence on the concrete mechanical damage under high temperatures. The material is considered as two-phase - aggregate and matrix - and three-phase - in which the interfacial transition zone is added. Concerning geometries, models in 2D and 3D are simulated. A finite element software is used with a weak coupling strategy that reduces the computational cost, and a user subroutine is implemented to define the constitutive model. The results show that the aggregate size influences both the average damage and the damage distribution along the synthetic specimen.