Plastic-Damage Model for Cyclic Loading of Concrete Structures

TLDR

The study develops a plastic‑damage model for concrete under cyclic loading that integrates fracture‑energy‑based damage with stiffness degradation within continuum damage mechanics. The model introduces separate tensile and compressive damage variables, a multi‑hardening yield function, and decoupled elastoplastic and degradation relations, using a scalar stiffness‑degradation law that governs yield‑surface evolution and is validated through numerical simulations of monotonic and cyclic loading.

Abstract

A new plastic-damage model for concrete subjected to cyclic loading is developed using the concepts of fracture-energy-based damage and stiffness degradation in continuum damage mechanics. Two damage variables, one for tensile damage and the other for compressive damage, and a yield function with multiple-hardening variables are introduced to account for different damage states. The uniaxial strength functions are factored into two parts, corresponding to the effective stress and the degradation of elastic stiffness. The constitutive relations for elastoplastic responses are decoupled from the degradation damage response, which provides advantages in the numerical implementation. In the present model, the strength function for the effective stress is used to control the evolution of the yield surface, so that calibration with experimental results is convenient. A simple and thermodynamically consistent scalar degradation model is introduced to simulate the effect of damage on elastic stiffness and its recovery during crack opening and closing. The performance of the plastic-damage model is demonstrated with several numerical examples of simulating monotonically and cyclically loaded concrete specimens.