Flexural behaviour of prestressed reinforced concrete beams strengthened with carbon plate

This paper presents the effect of carbon plate length on the deflection and ultimate moment of resistance of a prestressed flexural member. Numerical and experimental results are also included. Three typical failure modes were observed in the experimental programme: bending failure, end shear failure and peeling off of the carbon plate. The geometry of the beam was chosen so that three typical failure modes occurred when different carbon plate lengths were applied. The experimental results show that for the selected geometry of the prestressed concrete beam, the ultimate moment capacity of carbon-fibre-reinforced polymer (CFRP) strengthened beams is up to 3.66 times that of beams without CFRP reinforcement. However, the stiffness can be increased by as much as 52% using CFRP. Non-linear analyses of pre-tensioned beams, with and without CFRP strengthening, were compared with respect to the ultimate limit state. The experimental test results and numerical calculations showed very good agreement in terms of the yield load and ultimate load.