Modified models to predict the ultimate flexural and shear capacities of CFRP repaired RC beams

Abstract

Research is still ongoing to establish accurate models to predict the ultimate capacity of carbon fiber reinforced polymer (CFRP) repaired Reinforced Concrete (RC) beams, despite the numerous studies that have been conducted in this area. Previous studies suggested that more research is needed to better understand concrete behavior at flexural and shear, as well as the interaction between RC beams and externally bonded CFRP sheets. This study aims to experimentally validate the equations provided by the ACI 440.2 code for calculating the ultimate flexural and shear capacity of damaged RC beams repaired with CFRP sheets. The two design criteria for flexural capacity are the minimum and maximum steel ratios. Likewise, the two design criteria for shear capacity are having and not having shear stirrups. Moreover, two shear locations are investigated as the shear capacity at the quarter-span and shear capacity at 1.5d (d is the beam depth from supports). Finally, modified models are proposed to calculate the flexural and shear capacities, considering the contributions from other parameters to better correlate with the experimental results. The study concluded that the current ACI models result in differences from experimental results of up to 21%, 64% and 25% for flexural capacity, shear capacity at quarter-span and shear capacity at 1.5d, respectively. The modified models result in differences from experimental models of 6.9%, 2% and 7.3% for flexural capacity, shear capacity at quarter-span and shear capacity at 1.5d, respectively.