Fracture toughness of fibre-reinforced concrete determined by means of numerical analysis

As is well-known, the addition of fibres to concrete mix (Fibre Reinforced Concrete, FRC) produces a positive effect on cracking behaviour. In this work, the results of an experimental campaign on FRC specimens with randomly distributed micro-synthetic polypropylene fibrillated fibres are examined. The tests concern single notched beams under three-point bending, where the fibre content varies. Such an experimental testing is numerically analysed through a non-linear finite element model, named 2D-PARC, where a proper constitutive law for fibre-reinforced concrete is implemented. The load-crack mouth opening displacement (CMOD) curves numerically obtained are employed to determine the critical stress-intensity factor (fracture toughness) for different values of fibre content, according to the two-parameter model. The comparison between such numerical results and those obtained by applying the two-parameter model to the experimental load-CMOD curves is performed.