Shear behavior of non-prismatic continuous self-compacting concrete beams strengthened by CFRP bars or laminates

This study investigates the shear behavior of reinforced concrete continuous non-prismatic beams (RCNBs). The experimental program involves testing fourteen self-compacting concrete (SCC) beams, including twelve non-prismatic and two prismatic beams. All specimens were designed with identical longitudinal reinforcement, length, and width. The prismatic beams maintained a uniform depth of 250 mm, whereas the non-prismatic beams had decreased depths of 200 mm and 150 mm in the middle third. The depth at the supports was uniformly 250 mm for all beams. Each specimen was tested under static monotonic loading until failure. The experimental findings demonstrate a decrease in both the initial cracking load and the ultimate load capacity of the non-prismatic beams as the inclination angle increased. The ultimate load capacity decreased by approximately 25% and 39%, while deflection increased by 10% and 26% as the inclination angle varied from α = 0° to α = 6.5° and α = 13°, respectively, under consistent length, width, longitudinal reinforcement, loading, and support boundary conditions. The use of stirrups increased the stiffness of beams, resulting in enhanced shear capacity. Moreover, external shear strengthening utilizing carbon fiber-reinforced polymer (CFRP) bars or laminates improved the shear capacity of non-prismatic beams by approximately 30% due to improved confinement. Additionally, Finite Element analysis was employed to validate the experimental results. The numerical analysis showed good agreement with the experimental findings, particularly regarding load capacity, deflection, and overall behavior of the beams.