Prediction of Shear Contribution for the FRP Strengthening Systems in RC Beams: A Simple Bonding-based Approach

This paper introduces a novel and simple model for estimation of the shear contribution of the fiber-reinforced polymer (FRP) strengthening system in the FRP-strengthened beams. The model utilizes the bonding-based approach, which considers the shear resisting mechanism of FRP-strengthened beam via the bond behavior between FRP strengthening system and concrete. Herein, the beams strengthened in shear with near-surface mounting (NSM) rods or laminates and embedded through-section (ETS) bars are examined. By utilizing only mechanical consideration, the shear resistances of the NSM-strengthening or ETS-strengthening laminates or bars in the beams are simply derived when several bond factors (i.e. maximum bond stress and slip at peak bond stress) are known without using any empirical coefficients. The reliability of the proposed model is first validated against the test results available in the open literature. The extensive investigation to complement the model validation is then carried out through comparison of the results produced by the experiments and the proposed approach as well as the existing methods. The analyses demonstrate that the bonding-based approach is greatly effective to predict the shear contribution of the FRP strengthening system in the beam. Two examples for calculation of the shear resisting forces of the ETS-FRP and NSM-FRP bars in the FRP-strengthened beams are provided to depict the use of the model.