Novel constitutive model of UHPC under impact and blast loadings considering compaction of shear dilation

Abstract

Based on the framework of elastic-plastic-hydrocode concrete model, this study established a novel constitutive model of ultra-high performance concrete (UHPC) for impact and blast loadings considering the compaction of shear dilation. First, the established UHPC model is introduced, including five parts: (i) the dynamic failure strength surface, which is divided into tensile, compressive, and tensile-to-compressive regions and considers the Lode-dependence and strain rate effect; (ii) equation of state (EOS) that accounts for the nonlinear volumetric compaction; (iii) damage of strength, which contains independently described tensile and compressive strength hardening or softening formulae; (iv) damage of stiffness for depicting the compaction of shear dilation; (v) plastic flow rule, where the radial return algorithm is adopted for updating stress and an independent plastic potential function is employed to model the shear dilation. Then, parameters of the established UHPC model are systematically calibrated according to tests and empirical suggestions, and are further validated by conducting single element tests under varying loading paths. Through simulating the tests of reinforced UHPC beams/columns and UHPC filled steel tubes under drop hammer impact and reinforced UHPC panels under field explosion, it demonstrates that both the damage patterns and deflection-time histories of UHPC members are precisely reproduced by the established UHPC model. Furthermore, based on comparative simulations, it shows the compaction of shear dilation is critical for predicting the structural residual deflection of reinforced UHPC members. This study discloses a possibility to establish a constitutive model of concrete suitable for impact and blast scenarios with a wide range of strain rate and hydrostatic pressure.