ABSTRACT
In the present study, a mathematical framework for modeling the behavior of concrete under large deformations is developed. To capture the full degradation process of concrete, an over-nonlocal damage–plasticity theory based on an implicit gradient formulation is employed. Specifically, the coupling between plasticity and damage enables the description of both irreversible deformations and the softening characteristic of concrete, while the nonlocal formulation eliminates localization and mesh dependency, ensuring a realistic prediction of the material response. In addition, a finite element formulation is derived, incorporating the equilibrium equations along with an additional field associated with the Helmholtz-type equation of the gradient-enhanced model. The evolution equations are numerically integrated using a strongly objective algorithm, and the stress-update procedure is presented. Finally, the predictive capabilities of the proposed framework are demonstrated through simulations of reinforced concrete specimens, focusing on the loss of stability and failure of reinforced columns under compressive loading.
