Development of an inverse analysis procedure for the characterisation of softening diagrams for FRC beams and panels

The flexural performance of fibre reinforced concrete (FRC) materials is directly related to the stress-crack opening diagram (COD). This diagram is needed for structural design applications because it represents the energy change in the fracture process zone at the material level. In this paper, a novel inverse analysis procedure for the determination of the COD for FRC standard beams (EN14651) and round panels (ASTM C1550) is presented and validated. This procedure is based on a data fitting algorithm, for which the shape of the COD is not fixed a priori (free to vary). The efficiency of this procedure is demonstrated through experimental results for the three-points notched beam and the round panel standardised FRC characterisation tests. It is worthy to mention that inverse analysis procedures for panels are, to author's knowledge, very scarce, and this procedure can be easily extended to cover several kinds of beams and panels.