An improved mesoscale damage model for quasi-brittle fracture analysis of concrete with ordinary state-based peridynamics

Abstract

Ordinary state-based peridynamics (OSPD) is a promising computational method to analyze damage and fracture process because its equation of motion is still satisfied at the presence of discontinuities. Though OSPD has been introduced to evaluate mesoscopic behavior of concrete, there are many unsolved issues to tackle quasi-brittle behavior of mesoscopic constituents. In this paper, an improved mesoscale damage model for two-dimensional fracture analysis of concrete is proposed. Instead of modeling the interfacial transition zone (ITZ) with material points, the mechanical behavior of ITZ is embedded in the corresponding bonds of mortar and aggregates to improve modeling and computational efficiency. During the failure process, the damage initiation criterion is established based on the stress computed from the scalar force density; while the softening is characterized by the fracture energy and an exponential softening law. The proposed model is verified by simulating cracking of ITZ in uniaxial tension as well as crack propagation of concrete in three-point bending test. The prediction results show good agreements with either analytical or experimental results. Then, the model is employed to study mesoscale crack initiation and propagation of concrete under uniaxial tension, considering the distributions of mortar, aggregates, ITZ, and voids. Influences of the mesoscopic fracture properties on the macro constitutive relationship are also investigated through parametric studies. The improved mesoscale damage model presented is a simple yet effective tool for fracture analysis of concrete.