Evaluation and assessment of debon -ding model in RC beams strength -ened by external bonding of CFRP

One of the important applications of composite material in civil engineering is the strengthened of reinforced concrete beam in situ by an externally bonded carbon fiber reinforced plastic (CFRP). To determine ultimate capacity of these beams failure mechanism and relationships between external load and shear stress distribution at concrete/plate interface must be considered. Different failure mechanisms in this type of beams occur. The failure modes due to the tensile fracture of FRP،the crushing of concrete in compression or the plate separ -ation in the plate/concrete interface. In this paper a parametrical study using the non-linear model is made to obtain the analytical equation capable of calculating the maximal shear stresses at the interface plate/concrete aimed to anticipate the debonding load. And finally for evaluation of credibility of this equation we compared the experimental results obtained by different researchers.