Analysis of Premature Rip-Off Failure Mechanism of Reinforced Concrete Beams Strengthened with FRPs

Various types and forms of FRP materials have been applied for structural strengthening of reinforced concrete (RC) beams. When CFRP plates are used, however, a premature failure used to occur before strengthening effect appears adequately. This is primarily due to the rip-off of CFRP plate attached on RC beams. Despite of numerous studies on the rip-off failure of externally strengthened RC beams, the failure mechanism is not clearly explained yet. Investigations from the literatures have shown that the rip-off failure is dependant on vertical and shear stresses at the level of main reinforcements in RC beams. This study suggests an analytical model to investigate the ripoff failure load based on the stresses at the level of main reinforcements. The proposed model is relatively simple and produces very comparable results to the test data. Therefore, it is anticipated that the proposed model can be successfully used to provide further information on the rip-off failure mechanisms and its prevention.