A method for constructing the bilinear tension softening diagram of concrete corresponding to its true fracture energy

For the analysis of cracked concrete structures using the fictitious crack model two fracture properties of concrete are required, namely its true specific fracture energy G_F and the corresponding tension softening relation σ(w). In a recent paper, the authors proposed a simple method for the determination of the true specific fracture energy of a concrete mix. In this paper a method is proposed based on the concept of a non-linear hinge for constructing a bilinear approximation of the tension softening relation consistent with the true specific fracture energy G_F. The parameters of this bilinear approximation are inferred in an inverse manner. It is shown that this inverse identification procedure predicts accurate bilinear softening relations of concrete mixes tested in three-point bend and wedge-splitting modes.