Meso-scale numerical simulation of the effect of aggregate strength on damage and fracture of high-strength concrete under dynamic tensile loading

The dynamic mechanical behavior of high-strength concrete is sensitive to aggregate properties, thus an accurate description of the effect of aggregate strength on the dynamic tensile mechanical properties of high-strength concrete is essential to evaluate the structural stability of concrete. In this paper, a concrete meso-scale modeling framework was proposed based on discrete element method (DEM). The meso-scale model considered the three-dimensional meso-structure of concrete (coarse aggregate, mortar and interfacial transition zone), and the crushable aggregate model with realistic morphological characteristics was generated by the "clump-cluster " method. Based on this, the effects of aggregate strength on dynamic tensile properties and damage behavior of high strength concrete were quantitatively studied by splitting tensile test. The simulation results reveal the influence of aggregate strength and strain rate on the tensile properties of concrete at both macroscopic and mesoscopic levels, including dynamic deformation behavior, microcracks propagation mode and the proportion of different kinds of microcracks at different loading stages. The results show that the aggregate strength plays an important role in the dynamic tensile properties of concrete. The failure behavior of concrete and the damage degree of different components under dynamic tensile loading are influenced by the ratio of aggregate strength to mortar strength.