MESO-SCALE SIMULATION OF SIZE EFFECT OF DYNAMIC TENSILE STRENGTH OF CONCRETE UNDER LOW STRAIN RATES

Great progresses have been made in static size effect of concretes, while few efforts have been conducted in dynamic size effect of concretes. Herein the study, in order to explore the size effect of concrete under dynamic loadings, considering concrete heterogeneities and the strain rate effect for the meso components, a meso-scale simulation method was built. Taking the double notched concrete specimens as examples, the dynamic tensile failure and the size effect of concrete under low strain rates from 10^-5 s^-1 to 1 s^-1 were investigated using the meso-scale simulation method. The effect of strain rate on the size effect in tensile strength of concrete was also analyzed. Finally, based on the influencing mechanism of strain rate effect on dynamic strength and size effect, i.e. the enhancement of strength and weakening of size effect, a "static-dynamic unified size effect law" for dynamic tensile strength of concrete was established. The proposed size effect law was also calibrated by meso-scale simulation results.