Numerical study on dynamic shear properties of concrete under high loading rates

Abstract

Under high dynamic loads, the destruction of concrete structures is significantly influenced by the dynamic shear properties of concrete, especially when local failure occurs. Previous experimental studies have demonstrated that the shear behaviors of concrete exhibit a considerable strain rate effect. This study aims to numerically investigate the influence of the material parameters and the stress states on the shear properties and to further explore the mechanism of the shear strain rate effect. A mesoscale concrete model with the consideration of randomly distributed coarse aggregates, mortar matrix, and interfacial transition zone (ITZ) is developed to simulate the responses of concrete specimens subjected to shear loads at various loading rates. The model was validated by comparing numerical results with experimental data. Parametric studies were conducted to examine the influence of concrete parameters and confining pressures on its dynamic direct shear strength. The results indicate that the rate effect on the direct shear strength of concrete is substantial. The main reason is that more aggregates are damaged under high loading rates. Larger coarse aggregate size, smaller shear section size and high strength of ITZ could increase the rate sensitivity of the concrete in varying degrees. Additionally, confining pressure significantly enhances the direct shear strength of concrete but mitigates the influence of loading rates.