Replacing stirrups with steel fibers in high-strength concrete beams

Abstract

This study examines the feasibility of eliminating the minimum stirrups in reinforced high-strength concrete (HSC) beams by incorporating 0.75% (by volume) of hooked steel fibers. In addition, the shear capacity of steel-fiber-reinforced HSC (SFRHSC) beams without stirrups was compared with plain HSC beams with various amounts of stirrups. For this, ten large reinforced HSC beams, with and without stirrups and steel fibers, were fabricated and tested. Test results indicate that the SFR-HSC beams exhibited higher flexural strength but lower ultimate deflection capacity and ductility than the plain HSC beams. The failure mode of lightly-reinforced HSC beams was transformed from concrete crushing at the compressive zone to longitudinal steel bar rupture by including the steel fibers. However, both the reinforced HSC and SFRHSC beams exhibited flexural failure modes, and 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 steel fibers. Furthermore, a portion of shear stirrups was able to be eliminated by using 0.75 vol% steel fibers, and the amount of stirrups eliminated were quantitatively evaluated.