Fracture behavior of concrete beams reinforced with mixed long/short steel fibers

This work presents the results of an experimental activity carried out on Fiber-Reinforced Concrete (FRC) obtained by mixing short and long hooked-end steel fibers. Eleven mixtures were considered including plain concrete as a reference and steel-FRC with 0.5% and 1.0% of fiber volume fractions. The experimental campaign was aimed at observing the key aspects of the mechanical behavior of FRC in bending. Particularly, the study was focused on examining the results of four-point bending (4 PB) tests performed on notched prisms. The structural behavior was evaluated in terms of traction–separation law of FRC and the possible influence of both amount and type of fibers was investigated. Finally, a non-linear cracked hinge model was presented through an appropriate meso-mechanical approach aimed at simulating two key crack-bridging mechanisms of fibers. Comparisons between experimental data and numerical predictions were discussed.