influence of the meso-structure in dynamic fracture simulation of concrete under tensile loading

in order to understand the loading-rate sensitivity of concrete, we simulate direct tensile-tests for strain rates ranging 1–1000 s⁻¹. we investigate the influence of aggregate properties (internal ordering, size distribution and toughness) on peak strength and dissipated fracture energy. we show that a rate independent constitutive law captures the general increase of peak strength with strain rate. however, a phenomenological rate-dependent cohesive law is needed to obtain a better agreement with experiments. furthermore, at low rates, peak strength is sensitive to the inclusions' toughness, while the matrix dominates the mechanical behavior at high rates.