Response of steel fiber reinforced high strength concrete beams: Experiments and code predictions

The shear-flexure response of steel fiber reinforced concrete (SFRC) beams was investigated. Thirty-six reinforced concrete beams with and without conventional shear reinforcement (stirrups) were tested under a four-point bending configuration to study the effectiveness of steel fibers on shear and flexural strengths, failure mechanisms, crack control, and ductility. The major factors considered were compressive strength (normal strength and high strength concrete up to 100 MPa), shear span-effective depth ratio (a/d = 1.5, 2.5, 3.5), and web reinforcement (none, stirrups and/or steel fibers). The response of RC beams was evaluated based on the results of crack patterns, load at first cracking, ultimate shear capacity, and failure modes. The experimental evidence showed that the addition of steel fibers improves the mechanical response, i.e., flexural and shear strengths and the ductility of the flexural members. Finally, the most recent code-based shear resistance predictions for SFRC beams were considered to discuss their reliability with respect to the experimental findings. The crack pattern predictions are also reviewed based on the major factors that affect the results.