Effects of steel fibers on shear behavior of high-strength reinforced concrete beams

The paper describes an experimental study that consisted of beam specimens made of Normal Strength Concrete (NSC) and of High Strength Concrete (HSC), with and without steel fibers that were subjected to predominant shear in four-point loading tests. HSC specimens included the four combinations of beams with and without fibers, with and without stirrups. The experimental program included study of the effects of concrete strength and inclusion of steel fibers on the load capacity, load-deflection curve and mode of failure. The results show that the effect on the shear capacity of the hooked-end steel fibers that were used in the tests was more pronounced when no shear reinforcement was used and that in the presence of stirrups fibers affected mainly the structural ductility and mode of failure. The results from the current study are also compared with the predictions of various theoretical models and of the American and European design codes. Examination of the results also shows that a required contribution of the shear reinforcement, which is determined according to the concrete capacity, leads to an increased amount of minimum shear reinforcement. However, the overall response of the beams that were tested shows otherwise.