New Approach to Predict Shear Capacity of Reinforced Concrete Beams Strengthened with Near-Surface-Mounted Technique

Understanding the shear behavior of a concrete beam is still a challenging task due to several complex mechanisms involved. The Modified Compression Field Theory (MCFT) demonstrated an ability to predict, with good accuracy, the shear capacity of reinforced concrete (RC) members. Due to its iterative nature, the MCFT is not a straightforward design methodology, and a simplified MCFT (SMCFT) approach of this method was proposed to overcome this aspect. This model takes into account the tensile stress installed in the cracked concrete and inclination of the diagonal compressive strut, and requires a smaller number of model parameters than MCFT. This paper presents a new approach to predict the shear capacity of RC beams shear strengthened with fiber-reinforced polymer (FRP) laminates/rods applied according to the near-surface-mounted (NSM) technique. The new approach is based on the SMCFT and considers the relevant features of the interaction between NSM FRP systems and surrounding concrete, such as debonding of FRP laminate/rod and fracture of surrounding concrete of FRP. The experimental results of 100 beams strengthened with different configurations and shear strengthening ratio of FRP reinforcements are used to appraise the predictive performance of the developed approach. By evaluating the ratio between the experimental results to the analytical predictions (V-exp/V-ana), an average value of 1.09 is obtained for the developed approach with a coefficient of variation of 11%.