Strengthening and repair techniques using bonded fiber reinforced plastic (FRP) sheets have been used as a new technology for strengthening and repair reinforced concrete members. This technique is practically efficient method and very attractive alternative compared to the conventional methods due to the high strength-to-weight ratio, relative high stiffness, and ease of application of the FRP. This work presents an experimental program that aims to study the behavior of reinforced concrete beams strengthened and repaired in flexure using externally glued glass fiber reinforced plastic (GFRP) sheets. Twenty-four reinforced concrete beams were used in this study. The test parameters included three ratios of steel tension reinforcement, and the number of layers of GFRP sheets and their shape. Three beams were preloaded up to 0.7 the ultimate load (0.7 Pu) other three were preloaded beyond the ultimate load (Pu). The results showed an increase in beam flexure strength ranging between 10 % and 60 % and also showed an increase in cracking load. Two failure modes were observed (sheet debonding failure and flexure compressive failure), depending on the ratio of steel tension reinforcement and hence the beam yield strength. In both cases, the sheet finally debonded due to excessive deformation. A theoretical calculation (for ultimate load) based on the flexure theory was made and showed good agreement when compared to the experimental results. |
