Numerical study of dynamic behavior of concrete by meso-scale particle element modeling

Based on the Particle Element Method, a meso-scale dynamic model is developed for numerical study of the dynamic failure behavior of three-phase concrete i.e., aggregate, mortar, and interface, under different strain rates. First, a pre-processing approach based on the background grid search method proposed in our previous work is applied to generate the three-phase concrete specimen in meso-scale; second, the meso-mechanical parameters of three phases of concrete are determined by inverse method; and third, using the meso-scale dynamic model, the complete force-deformation relationship and the corresponding dynamic increase factors (DIF) at different strain rates are obtained for dynamic splitting tensile and uniaxial compression tests of concrete. The results match satisfactorily with the preceding experiments in related literatures. Different fracture patterns, consumed energy curves and force chain distributions are discussed under different strain rates, explaining the mechanism of strain rate effects in concrete. The numerical simulations show that the higher the strain rates, the more reticular meso-cracks occur, the kinetic and frictional energies become more important, and the force chains in the specimen exhibit more bifurcation, implying that the fracture process at high strain rates requires more energy demand to reach failure.