Influence of steel fibers on the dowel action of RC beams without stirrups

Abstract

Although many researchers have already studied the shear behavior of reinforced concrete (RC) beams, the contribution of each resisting mechanism to the shear capacity is not fully understood. The problem becomes more complicated when steel fibers are added to the concrete, which may affect those mechanisms differently. The results of an investigation on the influence of the addition of hooked-end steel fibers on the dowel action by the main reinforcement of RC beams are reported here. The experimental program included 16 specimens without stirrups in which the main variables were the fiber volume content and aspect ratio and the diameter of the longitudinal steel reinforcement. Four of those specimens were analyzed using digital image correlation to gather detailed information about the displacement field and the splitting crack opening development with loading. A mechanical model for the prediction of the relationship between dowel load and crack opening is also proposed. The obtained results show the effect of the splitting crack opening along the specimen on the dowel strength and that the addition of steel fibers to the concrete enhances the dowel action load-carrying capacity and varies according to the effectiveness of fiber action along the splitting crack.