Design Guideline for Shear Strengthening of Reinforced Concrete Beam Using CFRP Strip to Eliminate Debonding Failure

Background: Design guideline to obtain the dimension of CFRP laminate for eliminating premature deboning failure is vital to acquire the ultimate strength of shear strengthened reinforced concrete beam. Objectives: The main objective of this research is to offer a design guideline for shear strengthening of reinforced concrete beam using CFRP laminate by eliminating debonding failure. Methods/Statistical Analysis: In the guideline, the design strain of CFRP laminate was obtained based on the bond strength of concrete and finally the beam was designed for shear in accordance with Euro Code (EC 2). To verify the guidelines, three reinforced concrete beams were experimentally investigated including un-strengthened control beam, beam strengthened with proposed guideline and beam strengthened in accordance with ACI 440. Findings: Results showed that the strengthened beam with proposed guideline prevented the complete separation of CFRP shear strips before failed by flexure. The strains of CFRP laminate were found to be compatible with shear reinforcement. Strengthened beam of proposed guideline had 35% and 20% higher failure loads as compared to un-strengthened control beam and strengthened beam with ACI guideline respectively. In terms of design parameters, the proposed guideline had been satisfactorily verified through experimental investigations. Application/Improvements: The proposed guideline is recommended for shear strengthening of RC beam using CFRP laminate. However, future research is suggested to further investigate the effects of concrete cracks on bond strength of concrete.