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 polymers (FRP) sheets is studied in this paper using modified compression field theory(MCFT). The beam is considered to be under the combined effects of shear force and bending moment. Equilibrium and compatibility equations, as well as stress-strain relationships are developed for an element in the strengthened beam. Due to the extensive computations, a computer program wasdeveloped to solve the governing equations. The accuracy of the presented method herewas verified by the experimental results of 84 strengthened RC beams reported in the literature. Comparison between the measured and predicted results shows that the method can predict the shear behavior of the beam throughout its entire range leading up to failure. The method can also incorporate the effect of debonding of the FRP sheets in the analysis. The results of a case study indicates that preventing thedebonding of theFRP sheets from the web of the beam adds significantly to  the shear capacity, and in certain cases changes the failure mode from brittle to ductile.