Flexure-Shear Behavior of Hybrid Fiber-Reinforced Prestressed Concrete Beams

This study aims at understanding the effect of hybridization of the steel and synthetic fibers on the flexure-shear behavior of prestressed concrete (PSC) beams. The effect of different fiber reinforcement on the behavior of PSC beams are evaluated in two stages. First, fracture tests were conducted to understand the influence of fibers at the material level. Secondly, full-scale PSC beams were tested for evaluating the effect of hybrid fiber addition on the flexure-shear behavior. The test matrix consists of beams cast with fiber-reinforced concrete (FRC) having fiber dosages of 0.35%, 0.70%, and 1.0% by volume of concrete. All the beam specimens were tested at a shear span-to-depth ratio (a/d) of five under four-point bending configuration. Effect of hybrid fiber addition on the overall load-displacement, load-strain, and strain energy absorption capacity of PSC beams was analyzed. Results of hybrid fiber-reinforced specimens was compared with the results of steel and polyolefin fiber-reinforced beams. The test results portray that the addition of hybrid fibers stiffen the post-cracking response and increases the energy absorption capacity. The failure mode changed from flexure-shear (brittle) to flexure (ductile) mode with the addition of hybrid fibers. Change of failure mode occurred at dosages of 0.35% for steel and hybrid fibers and 0.70% for synthetic (polyolefin) fibers.