Rate-dependent constitutive law and nonlocal spallation model for concrete subjected to impact loading

An empirical rate-dependent cap model is proposed assuming that the effects of strain rate on the plastic loading surface and damage surface are separable and isolated from the static effect by considering the strength enhancement at high strain rates. Using the proposed rate-dependent constitutive model for concrete, the numerical simulations capture the overall qualitative behavior of concrete response to planar impact at different velocities. A simple nonlocal spallation failure model is developed to meet requirements of modeling concrete which especially includes strain rate effects. Numerical simulations for some dynamic tension experiments of concrete are carried out and reasonable results are obtained.