Experimental investigation of the shear behavior of steel fiber reinforced concrete slender beams without stirrups through crack kinematics and shear transfer mechanisms

This paper aims to contribute to a more rational understanding of the shear strength behavior of steel fiber-reinforced concrete beams without stirrups. For this purpose, an experimental program comprising eight slender beams varying the fiber content and type, tested in three-point bending configuration with a complete monitoring of the displacement fields of the failure span, was carried out. A detailed analysis of the shape and kinematics of the critical crack, associated with the investigation of the shear transfer mechanisms during the test given by mechanical models available in the literature, was performed. The theoretical-experimental analyzes proved to be a promising approach for quantifying the contribution of each relevant parameter to the shear capacity, such as the fiber concrete residual tensile response. The study, therefore, presents a contribution toward a rational and comprehensive methodology for the shear design of concrete members. The influence of shape and kinematics of the critical crack on the shear response is also reported and a theoretical explanation is provided to justify the fact that beams with the same characteristics have different cracking patterns but similar shear strength.