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Title: Shear Strengthening of RC Beams with NSM FRP — Influencing Parameters and A Theoretical Model

Author(s): Amir Mofidi, Lijuan Cheng, Omar Chaallal, Yixin Shao

Publication: Symposium Paper

Volume: 327


Appears on pages(s): 31.1-31.16

Keywords: Fiber-reinforced polymer (FRP); near-surface mounted (NSM); shear; concrete; steel reinforcement

DOI: 10.14359/51713352

Date: 11/1/2018

This paper evaluates the influence of the key parameters on the shear behavior of reinforced concrete (RC) beams retrofitted in shear using near-surface mounted (NSM) fiber-reinforced polymers (FRP) laminates and rods. The commonly observed debonding failure is considered in the study. The principal bond related parameters are examined, including the FRP effective bond length, the NSM FRP to concrete bond relation and the pull-off force of NSM FRP bonded from concrete surface. It is found that unlike the beams strengthened with externally bonded (EB) FRP, the effect of the existing transverse steel shear reinforcement on the shear contribution of FRP is not significant and should not be considered by the design models. The existing experimental results in the open literature also show that the internal steel shear reinforcement and the strengthening NSM FRP do not diminish each other’s contributions to the shear resistance of the RC beam. To precisely predict the shear contribution of NSM FRP of the strengthened RC beams corresponding to the debonding failure, a new prediction method is proposed in this study to consider the most influencing factors on the shear contribution of NSM FRP (Vf). The accuracy of the proposed equations is verified by comparing the predictions with the shear strength of a series of experimentally tested RC beams from the literature. Moreover, a comparison with other existing models shows that the proposed model achieves a better correlation with the experimental data than the other existing equations.