Recent Improvements to Release III of the K&C Concrete Model

Recent improvements are made to Release III of the Karagozian & Case (K&C) concrete model. This three- invariant plasticity and damage-based constitutive model is widely used to model a number of materials, including normal and lightweight concrete, concrete masonry, and brick masonry, to compute the effects of quasi-static, blast, and impact loads on structures. This most recent version of the model, made available starting with LS-DYNA® v971 as *MAT_CONCRETE_DAMAGE_REL3, incorporates a number of improvements to the original model that are described in this paper. The model now exhibits: (a) an automatic input capability for generating the data for generic concrete materials and (b) methods to reduce mesh-dependencies due to strain-softening. A simple method is implemented to regularize the fracture energy by internally scaling the damage function for the generic concrete model parameters. For user-defined material parameters, a method is developed that can preserve fracture energy using the results of either single-element or multi-element simulations. Finally, concrete loading rate effects are discussed and guidance is provided on properly modeling such effects with the model.