Shear Behavior of FRP-Reinforced Concrete Deep Beams without Web Reinforcement

The shear behavior of four full-scale deep beams reinforced with carbon and glass fiber reinforced polymer (FRP) bars were investigated. The beams were supported over a 3,000-mm span with a projection of 1,000 mm on each side, with a cross section of 300 mm in width and 1,200 mm in depth, and tested to failure under four-point loading. The primary test variables included the longitudinal reinforcement ratio and the reinforcement type. The reinforcement ratio and concrete compressive strength had a clear effect on the ultimate capacity and deflection characteristics while reinforcement type no clear effect of the behavior of the tested beams. The crack patterns, mode of failure, and strains in concrete and reinforcement were also reported. The formation of the tie action was confirmed by the nearly uniform strain distribution in the longitudinal reinforcement. The results are compared to the strut-and-tie model, demonstrating the necessity of including the effect of web reinforcement and the importance of considering the effect of axial stiffness on longitudinal reinforcement.