Three-Dimensional Damage Model for Concrete. I: Theory

Abstract

A damage model for concrete is proposed based on the existing displacement equivalence-based model for brittle materials. The model is established in a randomly selected coordinate system so as to consider the cases where the principal directions of damage do not coincide with those of stress and strain. The effect of shear stress is also considered. The slipping cracks of concrete under triaxial compression and the stiffness reduction under hydrostatic compression are also taken into account. The friction at crack tips has been introduced to account for the permanent deformation and a blend of elastic and secant unloading/reloading routine is obtained. The evolution rule of damage is combined with the predefined basic damage evolution patterns.