Abstract:

By using the particle discrete element method, a three-phase (aggregate, mortar and interface) meso-scaled concrete model is developed for investigating dynamic behaviour of concrete materials with an efficient pre-processing approach. Based on the presented model, the dynamic splitting tensile tests of concrete with different loading rates are performed by numerical simulation. The dynamic increasing factor (DIF) and failure patterns of concrete sample with different strain rates are obtained, which match quite well with the experimental results. The research indicates that, the higher the strain rates, the more cracks there are, which become reticular formation as well. Some of the cracks even penetrate the aggregates. Therefore, this process might require more energy comparing with the static process, which, in a sense, explains the higher strength of concrete in dynamic process. Further more, the force chain bifurcates at high strain rates; and the randomlity and nonuniformity of space distribution increase; consequently the dynamic strength of concrete has a stronger discreteness.

Key words: dynamic strength of concrete, mesomechanics, particle discrete element method, force chain