Modeling of Shear Behavior of Reinforced Concrete Beams with Corroded Stirrups Strengthened with FRP Sheets

Abstract

Because stirrups corrode earlier and faster than longitudinal steel bars, reinforced concrete (RC) structures may fail in shear instead of bending. Since shear failure is brittle and catastrophic, it is of significance to strengthen RC beams with corroded stirrups in shear. However, the shear behavior in strengthened RC beams has not yet been fully documented and explained. This paper presents a numerical investigation of the shear behavior of corroded RC beams strengthened in shear with fiber-reinforced polymer (FRP) sheets. The model described in this paper was based on modified compression field theory and can simulate the whole process from loading to shear failure. The proposed model was validated by collected experimental results. Influencing parameters that have prominent effects on the shear behavior were studied, including the corrosion degree, concrete strength, stirrup ratio, FRP sheet strengthening ratio, and strengthening methods. The numerical results proved that FRP strengthening, whether included as the wrapping or U-shaped bonding of FRP sheets, was effective to improve the shear strength of RC beams. It was found that the cracking load barely changed with the increasing corrosion degree of the stirrups, whereas the shear strength decreased gradually. With the increase in the stirrup ratio or the decrease in the concrete strength and FRP sheet strengthening ratio, stirrups provided a larger contribution to the shear behavior, and the shear strength decreased more significantly, as expected with corroded stirrups.