Evaluation of Rheological Models within Lattice-based Simulations of Concrete under Dynamic Loading

Abstract

Concrete is a highly rate dependent material. Its mechanical properties (e.g. strength, elasticity, ultimate strain) depend on the loading rate. For example, tensile strength increases with the loading rate. For intermediate loading rates the strength enhancement is related to the viscosity of free water within micro-/nano-pores in concrete, the so-called Stefan effect, whereas the strengthening effect at higher loading rates is dominated by micro-/meso-inertia of the material within the fracture process zone (FPZ). These rate dependent mechanisms should be included in the formulation for physically realistic modeling of concrete materials. In this study rheological material models are used to represent rate effects, where viscous components (e.g. dashpots) are connected to local spring elements within Rigid-Body-Spring Networks. Three types of constitutive relationships are considered: 1) visco-elastic, 2) visco-plastic, and 3) visco-elasto-plastic damage models. Direct tensile tests are simulated and characteristics of the three different rheological models are compared through their stress-strain responses