Experimental analysis of shear behavior of steel fiber reinforced concrete (SFRC) beams

Abstract

Steel fiber reinforced concrete (SFRC) is a composite in which the fibers act as reinforcement and control crack opening, modifying the post-cracking behavior of the matrix. The addition of the steel fibers in concrete enhances the shear capacity of beams. SFRC redistributes tensile stresses in diagonally cracked regions due to shear and increases overall strength. Shear failure is brittle in beams lacking or having insuficiente transverse reinforcement. The addition of steel fibers in beams promotes a ductile failure mode and representes an alternative to the use of stirrups. This research aims to investigate the influence of steel fibers on shear behavior of beams without stirrups. Fibers were added to concrete mixes with compressive strength of 30 MPa and 40 MPa, in quantities of 80, 100, and 120 kg/m³ (1%, 1.25%, and 1.50%, respectively). The beams were subjected to flexural loading, and their structural behavior was analyzed. The results indicate a change in the failure mode from brittle to ductile, along with a significant increase in load capacity, correlated with the increase in fiber content. Strain in the reinforcement bars was reduced due to presence of fibers. Experimental values were accurately predicted by the formulation provided in the Brazilian standard.