Flexural performance of CFRP strengthened beams - comparison with analytical model

ABSTRACT In recent years, strengthening methods for reinforced concrete structures using fibre-reinforced polymer (FRP) composites have been gaining widespread interest and growing acceptance in civil engineering industry. Near surface mounted (NSM) reinforcement as well as externally bonded reinforcement (EBR) sheets have emerged as new strengthening methods in which external reinforcement (in the form of bars or sheets) is embedded into grooves or adhered to the section with epoxy adhesive. This paper proposes a simplified analytical approach to predict flexural behaviour of simply supported reinforced-concrete (RC) beams strengthened with carbon fibre-reinforced polymer (CFRP) using the above-mentioned methods. The flexural capacity and deformational behaviour of FRP strengthened beams are analysed using trilinear moment curvature relationship at three critical points namely (i) crack initiation point (ii) steel yield initiation point and (iii) ultimate capacity point, based on strain compatibility and principles of equilibrium. A good predictive performance of analytical model is appraised by simulating force-deflection response registered in the experimental program composed of RC beams strengthened with NSM as well as EBR methods. The analytical solutions have also given accurate prediction of experimental results in the literature regardless of the arrangement of CFRP reinforcement.