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Shear strengthening of RC beams with NSM FRP—Influencing parameters and a theoretical model

Lookup NU author(s): Dr Amir MofidiORCiD



This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Concrete Institute, 2018.

For re-use rights please refer to the publisher's terms and conditions.


This paper evaluates the influence of the key parameters on the shear behaviour of reinforced concrete (RC) beams retrofitted in shear using near-surface mounted (NSM) fibre-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 the 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.

Publication metadata

Author(s): Mofidi A, Cheng L, Chaallal O, Shao Y

Publication type: Article

Publication status: Published

Journal: American Concrete Institute Special Publication

Year: 2018

Volume: 327

Pages: 31.1-31.16

Print publication date: 01/11/2018

Acceptance date: 01/08/2017

Date deposited: 01/02/2019

ISSN (print): 0193-2527

Publisher: American Concrete Institute