VISCOUS HARDENING PLASTICITY FOR CONCRETE IN HIGH-RATE DYNAMICS

This paper presents a constitutive model for concrete in high-rate dyn amics. The main feature outlined in this paper concerns the modeling o f strength enhancement due to rate effects at the macrolevel of materi al description. It is accounted for in the constitutive modeling of st rain and stresses within the theory of elastoplasticity by extending t he classical plastic model to viscous hardening plasticity. Rate effec ts are associated with a viscous phenomenon occurring within the pores of concrete. The model is worked out in a thermodynamic framework whi ch allows to account for couplings between viscous and plastic evoluti ons. The determination of the material parameters associated with the viscous phenomenon is achieved by using available data from dynamic di rect tensile tests. By way of example, the three-parameter Willam-Warn ke plasticity criterion is adapted to account for isotropic viscous ha rdening. Finally, some applications are shown to illustrate the capabi lities of the model to capture the basic features of concrete behavior in high-rate dynamics, with a minimum of material parameters of clear physical significance and accessible by existing material tests.