Splitting and crushing failure in FRC elements subjected to a high concentrated load

The local splitting behaviour in Fibre Reinforced Concrete (FRC) elements under a high concentrated load is gaining a growing interest, especially with reference to precast tunnel segments. In fact, during the lining construction process, high concentrated thrust jack forces are introduced in the segments leading to both high compressive stresses under the thrust shoes that can provoke a concrete crushing and tensile transversal stresses that can cause cracks and, eventually, a splitting failure. In order to investigate the main involved mechanisms during either splitting or crushing failure, a simplified analytical study is firstly presented on the two load configurations generally adopted in practice, namely the Line Load (LL) and the Point Load (PL). Based on this analytical study, experimental tests on Steel Fibre Reinforced Concrete (SFRC) specimens subjected to a LL configuration have been carried out. Two different steel fibre types have been studied. Experimental results indicate that the use of a low amount of fibres significantly enhances both the splitting bearing capacity and the ductility. Fibres allow a stable propagation of the splitting crack both in terms of crack opening and development, as a result of a transverse stress redistribution that continuously provide equilibrium with the external applied load.