Effect of flexural CFRP sheets on shear resistance of reinforced concrete beams

The current method of strengthening reinforced concrete (RC) beams in shear is by externally bonding carbon fiber reinforced polymer (CFRP) sheets to the vertical sides of the beam with different orientations and spacing using epoxy adhesives to arrest diagonal cracks. However, in certain applications, the sides of the beam might not be accessible for shear strengthening. The aim of this paper is to investigate the effect of externally bonded CFRP sheets on the load-carrying capacity of shear-deficient RC beams when attached to the beam’s soffit. This will examine the contribution of flexural longitudinal reinforcement ratio in enhancing the shear strength of RC beams. Thirteen beams were cast without transverse reinforcement in the shear span and were divided into three groups with different longitudinal steel reinforcement ratios. The tested specimens failed in shear as a result of a diagonal-tension crack. The increase in the concrete shear capacity of strengthened specimens was in the range of 10–70% compared to the control specimens. This concludes that flexural longitudinal reinforcement ratio has a significant effect on the shear strength of RC beams. The shear strength of the tested specimens were also predicted using different codes guidelines and standards.