A unified stochastic damage model for concrete under monotonic and fatigue loading

Abstract

This study proposes a unified concrete damage model that can be applied to both monotonic and fatigue loading scenarios. The proposed model adopts the framework of stochastic damage mechanics and considers the micro-spring in the micro-meso stochastic fracture model (MMSF) as an energy dissipation element. To describe the multiscale energy dissipation process of the micro-spring, the rate process theory and a crack hierarchy model are employed. It is found that the energy dissipation threshold is linked to the elastic strain energy of the micro-spring, and the derived fracture strain of the micro-spring in MMSF enables the proposed model to describe the damage evolution laws for both monotonic loading and fatigue loading. The underlying damage mechanisms associated with the two loading processes are analyzed in detail. Additionally, the energy dissipation analysis enables the definition of the corresponding micro-damage to the micro-spring, which leads to the demonstration of the nonlinear properties of the micro-spring's constitutive law. Finally, several numerical examples are presented to validate the model.