Parametric analysis on compressive strain rate effect of concrete using mesoscale modeling approach

To reveal the physical mechanism of strain rate effect of concrete subjected to compression with different loading speeds, parametric analysis on the nonlinear behavior of concrete was performed using mesoscale finite element (FE) modeling approach in this study. The effects of geometrical shape and distribution pattern of aggregates, interfacial transition zone (ITZ), loading approach, viscosity parameters, element meshing techniques and other mesoscopic influence factors on the failure pattern, compressive stress-strain relationship and dynamic increase factor (DIF) of concrete cubes were systematically investigated using explicit and implicit dynamic analysis respectively. The numerical findings indicate that the DIF is mainly induced by the inertial effect of the concrete specimen under dynamic loading and the strength enhancement should be considered in material definition. Besides, it has proved that the DIF is related to the variation of distribution pattern and geometrical shape of aggregates, and mesostructure randomness of concrete needs to be explicitly modeled in mesoscale numerical analysis. In addition, the viscosity parameter imposes significant influences on the convergence issues and the accuracy of numerical results from implicit dynamic analysis. More importantly, the variation trend of DIF is sensitive to the specific value of viscosity parameter. Key issues with regard to mesoscopic analysis of concrete specimen under dynamic loading were systematically investigated in this study and the research findings can provide valuable references for mesoscale modeling of concrete components subjected to dynamic loading with different strain rates. (C) 2020 Elsevier Ltd. All rights reserved.