A review of the effect of steel fibers on the shear capacity of concrete beams without shear reinforcement

Abstract

The shear strength of reinforced concrete beams is largely governed by the compressive strength of concrete, which represents a major component of the overall shear capacity. Incorporating steel fibers into the concrete matrix has been shown to enhance this capacity and significantly improve structural performance. A comprehensive review of previous experimental studies indicates that the shear strength is primarily influenced by the longitudinal reinforcement ratio and the shear span ratio (a/d), while the effect of compressive strength becomes more evident in high strength concrete. It was also observed that the inclusion of steel fibers at a volume fraction of approximately 0.75% can increase the shear strength of beams by 25-35% compared with plain concrete specimens. Moreover, steel fiber-reinforced beams demonstrated superior crack control and enhanced ductility, thereby reducing the risk of sudden brittle shear failure. Notably, the improvement in shear behavior was found to be relatively independent of the fiber type, while the overall workability of the concrete remained within acceptable limits. These findings highlight research gaps regarding the optimum fiber dosage under different loading conditions and long-term performance.