Localizing gradient damage model coupled to extended microprestress-solidification theory for long-term nonlinear time-dependent behaviors of concrete structures

Abstract

A nonlocal damage-based model is proposed to predict the nonlinear long-term deformation of concrete structures, which couples the localizing gradient-enhanced damage (LGED) model for crack nucleation and propagation to the extended microprestress-solidification (XMPS) theory for creep and shrinkage deformations. The proposed LGED-XMPS model circumvents damage localization by incorporating higher-order deformation gradients, and connects creep and shrinkage to inherent moisture transport and heat transfer processes. For creep part, a solidifying Kelvin chain is adopted for the rate-type formulation, which greatly reduces computational burdens of the conventional integral-type formulation. The LGED-XMPS model regularizes mesh-sensitivity of creep deformation intertwined with damage and cracking, which is rarely reported elsewhere. Furthermore, the model are validated with several tests reported in literatures. Specifically, the time-to-failure of concrete specimens subject to high level stresses is well predicted, along with the long-term deflections of simply-supported beams affected by crack growths. It is highlighted that the model is competitive for predicting nonlinear long-term deformation of creep- and crack-sensitive structures.