A GENERAL BILINEAR FIT FOR THE SOFTENING CURVE OF CONCRETE

The softening function is the main input needed to model the fracture of concrete when using a cohesive crack approach. The simplest softening function that describes concrete behaviour reasonably well is a bilinear one. It is defined by four parameters: the tensile strength f(t), the specific fracture energy G(F), and two parameters characterizing the shape of this function. Here it is shown how these parameters can be derived from experimental measurements on notched beam tests. In particular, the parameters characterizing the shape of the function come from knowledge of the tail of the load-displacement curve and from the recorded maximum loads when similar beams of different sizes are tested.