Mesoscopic investigation on the mechanism of concrete dynamic tensile strength enhancement based on the E(A, B) algorithm

The dynamic tensile strength of concrete shows a certain dynamic enhancement, whereas the potential mechanism of the dynamic enhancement has not been clearly revealed so far. This paper studies the mechanism of concrete dynamic tensile strength enhancement and identifies the contribution of various factors to the dynamic enhancement. In order to study the fracture of concrete under dynamic load, this paper first developed a threedimensional polyhedral aggregate packing program by adopting the algorithm of Entrance block between A and B (E(A, B)), which greatly simplifies the calculation of contact or overlapping judgment between two blocks in the modeling process. A cohesive model is then proposed to describe the fracture in the microscopic concrete model. Through the verification simulations, appropriate material parameters and mesh size are selected. Finally, the effects of the micro-crack inertia, material heterogeneity, the structural inertia and the material viscosity on the concrete dynamic tensile strength enhancement are discussed. The results show that the dynamic tensile strength of concrete is not significantly affected by the micro-crack inertia but is highly related to the material heterogeneity, the structural inertia and the material viscosity. Specifically, the material heterogeneity has a more pronounced effect on the dynamic tensile strength at higher strain rate. The contribution of the structural inertia effect and the material viscosity to the enhancement of dynamic tensile strength rank the second and first respectively, and their influence degree increase with the increase of strain rate.