Design model for shear capacity of RC beams strengthened with two-side CFRP wraps based on effective FRP strain concept

Abstract

A simple design model based on effective strain of fibre-reinforced polymer (FRP) to predict shear capacity of reinforced concrete (RC) beams strengthened with two-side FRP wraps is proposed. Five two-side carbon FRP wrapped and five control unstrengthened RC beam specimens were tested, and the obtained results in addition to the experimental results of 32 two-side wrapped RC beams selected from the literature were used to calibrate the model. Performance of the proposed model was compared with fib Bulletin 14 and ACI 440.2R design models. It was shown that fib Bulletin 14 and ACI 440.2R mostly overestimate the FRP contribution to the shear capacity of two-side wrapped RC beams, while ACI 440.2R model is incapable of predicting effective FRP strain for shear-strengthened shallow beams. Results of 20 independent tests on RC beams strengthened in shear with two-side wraps verified that the proposed model fairly estimates the shear capacity of the strengthened RC beams. It was justified and concluded that since the simple proposed model provides more accurate and safe predictions compared with existing guideline models, it may be capable to be used for design purposes.