On the modelling of the rate dependence of strength using a crack-band based damage model for concrete

Abstract

Concrete strength is reported in literature to increase with increasing strain rate, which needs to be considered in concrete constitutive models used for finite element analyses of concrete structures. One attractive group of constitutive models for concrete failure are scalar damage models using the crack band approach. These models are computationally efficient for rate independent loading because they produce mesh independent results with coarse discretisations as long as the strain field localises in mesh-dependent zones. The aim of this study is to incorporate the strain rate dependence in crack band based damage models while maintaining their ability to produce mesh-independent results. First the proposed model is described. Then, it used for direct tensile analysis in which strain softening occurs. It is demonstrated that a combination of strain rate dependent model for the undamaged response combined with a relative displacement rate dependent model for the damaged response provides stress-displacement curves which converge with mesh refinement.