The use of externally bonded carbon fiber-reinforced polymers (CFRPs) as strengthening systems to improve the condition and overall capacity of existing reinforced concrete structural members is found to be a promising scheme. This field has drawn the attention of many researchers in the past two decades through the implementation of much theoretical work as well as experimental studies. It was evident through many experimental investigations conducted by a number of researchers that the bond action between fiber-reinforced polymers and reinforced concrete members is considered one of the main factors affecting the performance and reliability of external strengthening systems and warrants further investigation. Debonding failure is a brittle mode of failure that may occur prematurely before strengthened members develop their full composite and expected capacities. This paper aims to investigate the bond behavior between the CFRP-concrete interface via experimental work and finite element (FE) simulations. The experimental study consisted in testing nine concrete prisms with different bonded lengths of the CFRP plates that vary between 25% (60 mm), 50% (120 mm), and 75% (180 mm) of the total length of the concrete prisms and instrumented with strain gauges. A FE simulation model was created and validated using the experimental results of the tested specimens, and a parametric study was carried out to investigate the effect of several parameters on the bond behavior between CFRP and concrete surfaces. The trend of the FE simulation results shows a good agreement with the experimental results and those available in the literature. It was observed that the optimum length of the CFRP plate is in the range between 150 mm and 160 mm when bonded to concrete surfaces. Other conclusions and observations were drawn based on the experimental and numerical results.

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