Determination of quasibrittle fracture law for cohesive crack models

Abstract A basic and necessary ingredient of cohesive crack models, so widely used for numerical quasibrittle fracture simulations, is the softening function which characterizes the property of concrete-like materials. In this paper, a simple procedure to determine the softening parameters for such functions is proposed. In addition to knowledge of the tensile strength—typically obtainable within about 20% from a cylinder splitting strength (Brazilian) test—the only other requirement is knowledge of the load-displacement curve, as would be obtained from a standard three-point bending test. The method is particularly suitable for materials, such as fiber reinforced concrete, which exhibit a long tail in their load-displacement response. Although suitable for identifying both nonlinear and piece-wise linear relations, we illustrate applications of the scheme using a bilinear law.