Influence of steel fibers on full-scale RC beams under shear loading

The use of Fiber Reinforced Concrete (FRC) has gained considerable attention in the last few years, particularly when crack propagation control is of primary importance, such as in slab-on-grade applications or in beams when shear reinforcement is partly or totally absent. Many experiments available in the liter-ature showed that fibers, if provided in sufficient amount, are significantly effective as shear reinforcement. Fibers limit the growth of shear inclined crack, give visible warning prior the structure collapse and also provide a stable and diffused crack pattern within the shear critical area. However, the issue of size effect in members containing steel fibers, has not been deeply investigated and evaluated yet. This paper studies the beneficial influence of fibers on the size effect in members without conventional shear reinforcement. Moreover an extensive parametrical numerical study, performed by means of a FE program based on the Modified Compression Field Theory (MCFT), suitably adapted to FRC materials, is herein presented.