Determination of quasibrittle fracture law for cohesive crack models

A basic and necessary ingredient of cohesive crack models, so widely used f or numerical quasibrittle fracture simulations, is the softening function w hich characterizes the property of concrete-like materials. In this paper, a simple procedure to determine the softening parameters fur such functions is proposed. In addition to knowledge of the tensile strength-typically ob tainable within about 20% from a cylinder splitting strength (Brazilian) te st-the only other requirement is knowledge of the load-displacement curve, as would be obtained from a standard three-point bending test. The method i s particularly suitable for materials, such as fiber reinforced concrete, w hich exhibit a long tail in their load-displacement response. Although suit able for identifying both nonlinear and piece-wise linear relations, we ill ustrate applications of the scheme using a bilinear law. (C) 1999 Elsevier Science Ltd. All rights reserved.