A way for preventing tension delamination of concrete cover in midspan of FRP strengthened beams

In order to prevent tension delamination of concrete cover in midspan more efficiently, an attempt to strengthen reinforced concrete beams by combining unidirectional carbon fibre reinforced polymer (CFRP) sheet (to bond to the tension faces of the beams) and bi-directional glass fibre reinforced polymer (GFRP) sheet (to wrap 3 sides of the beams continuously) was proposed. The feasibility and potential advantages of the attempt were discussed. A comparative test program including ten beams was carried out. The test results showed that the hybrid CF/GF reinforced polymer (H-CF/GF-RP) strengthening could not only prevent the tension delamination of the bottom concrete cover, but also lead to a significant increase of deformation capacity of the strengthened beams at a very low cost compared to CFRP strengthening.