Seismic performance of reinforced concrete beam-column joint strengthening by frp sheets

Reinforced concrete beam-column joints are generally recognised as critical regions in frame structures which experience severe inelastic deformations during earthquakes. This paper presents the results of an experimental campaign to investigate the optimal seismic performance of a method of strengthening reinforced concrete beam-column joints. Ten reinforced concrete beam-column joints, at a scale of one to three (1/3), were subjected to reverse cyclic loading under constant axial load to simulate an earthquake, and tested with the deflection being monitored. The joints were strengthened with fibre-reinforced polymer (FRP) systems, made up of a combination of carbon and fibreglass fabric, and a hybrid braided FRP fabric. Of these, four samples were strengthened with different FRP systems, while two were used as benchmarks. Once damaged, four specimens were repaired with FRP and re-tested. Strain and cracking fields were monitored using an Aramis digital video camera. The test results provided useful information on the strengthening configurations adopted, in relation to strength, ductility and energy dissipation capacity. The results establish the efficiency of glass fibre GFRP in upgrading deficient beam-column joints in an equivalent proportion than carbon fibre CFRP. It was observed that using of a hybrid sheet (Glass-Carbon) improves the ductility and dissipation energy of the RC joints to a great extent, with a highly competitive cost.