In order to repair many structures damaged in Wenchuan earthquake, using carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) to repair the reinforced concrete (RC) beams was studied. The failure types, stiffness change, crack developing characteristics and shear resistance were investigated. Beam size, stirrup ratio, FRP type and arrangements of sheets along the shear span were analyzed during experimental study. The test result indicated that CFRP or GFRP can increase the shear resistance and deformability greatly, and the rigidity of strengthened beams also increases obviously. Compared to strengthening with CFRP, the GFRP strengthening method increase the deformability and the utilization ratio of strengthening material. The shear resistance increases with the beam height, but not fit for the deformability. Increasing stirrup ratio can delay the crack appearing obviously, improve the cracking load and ultimate strength of strengthened beam, but reduce the ultimate deflection greatly. Finally, according to the analysis of test data, the theoretical and practical formula for calculating the bearing capacity of RC beams strengthened with FRP sheets was established. The results showed that the theoretical calculation is in accord with the experimental data.
