Feasibility of replacing minimum shear reinforcement with steel fibers for sustainable high-strength concrete beams

This study aims to investigate the feasibility of eliminating the minimum shear reinforcement in reinforced sustainable high-strength concrete (HSC) beams by incorporating 0.75% (by volume) of hooked steel fibers. To do this, five large reinforced HSC beams, with and without stirrups and steel fibers, were fabricated and tested. In order to have minimum shear reinforcement, the reinforced HSC beams were designed with longitudinal steel bar ratios of 0.64-0.72%. Test results indicate that the use of 0.75 vol% of steel fibers (instead of stirrups) leads to higher flexural strength but lower ultimate deflection and ductility. The failure mode of lightly-reinforced HSC beams was transformed from concrete crushing to longitudinal steel bar rupture by including the steel fibers. However, both the reinforced HSC and steel-fiber-reinforced concrete (SFRC) beams exhibited flexural failure modes; as a result, it was concluded that the minimum shear reinforcement for reinforced HSC beams can be efficiently eliminated by including 0.75 vol% of hooked steel fibers. In addition, the flexural behavior of reinforced SFRC beams was successfully simulated based on sectional analysis by considering fiber orientation factor.