Analysis of RC beams strengthened with FRP sheets under shear and flexure using MCFT

Shear behavior of Reinforced Concrete (RC) beams strengthened with Fiber Reinforced Polymer (FRP) sheets is studied in this paper using Modied Compression Field Theory (MCFT). The beam was considered to be under the combined effects of shear force and bending moment. Equilibrium and compatibility equations as well as stress-strain relationships were developed for an element in the strengthened beam. Due to the extensive computations, a computer program was developed to solve the governing equations. The accuracy of the presented method was veried by the experimental results of 84 strengthened RC beams reported in the literature. Comparison between the measured and predicted results showed that the method could predict the shear behavior of the beam in its entire range up to failure. The method could also incorporate the effect of debonding of the FRP sheets in the analysis. The results of a case study indicated that preventing the debonding of FRP sheets in the web of the beam would significantly increase the shear capacity and, in certain cases, change the failure mode from brittle to ductile.