A coupled creep and damage model of concrete considering rate effect

Abstract

From experimental perspective, it is well-known that relationship between concrete creep and loading level is nonlinear at middle and high loading levels. This nonlinear characteristic is considered to be closely related to micro-crack propagation and damage accumulation in concrete during creep. It has also been revealed in experiments that the strength of concrete under long-term sustained loading is significantly lower than that under static loading test, which can also be ascribed to the nonlinear characteristic (micro-crack propagation and damage accumulation) under long-term sustained loading. Focused on the nonlinear creep of concrete at middle and high loading levels, a coupled creep and damage model considering rate effect is constructed at meso-scale in this study. In the coupled creep and damage model, the creep behavior of concrete is characterized using B3 model and rate effect is taken into account by modifying Mazars damage model via intensity amplification factors DIFs. The presented model is validated through comparisons with experiment results from literatures. The dynamic damage mechanism and nonlinear creep mechanism are comprehensively analyzed and discussed using the model. It is proven that the presented model is capable of characterizing the nonlinear creep and creep failure of concrete at medium and high loading levels. The consideration of rate effect in calculation shows better results and the characterization of its role on the creep evolution is correct and essential.