Seismic Rehabilitation of RC Beam-Column Joints Using FRPs

RC frames, when subjected to earthquake, must dissipate large amounts of energy. This can be achieved when the beam-column joints are designed in such a way that the plastic hinges form at a distance away from the column and the joint region remains elastic. In existing frames, a practical way to implement this behaviour is to use FRPs. In this study, two plain scaled-down sub-assemblies and five retrofitted/repaired specimens using a new technique called web-bonded FRP were tested under monotonic/cyclic loads. It was concluded that the use of FRPs can restore/upgrade the integrity of the joint, keeping/improving its strength, stiffness and ductility, and can relocate the plastic hinges away from the column. An analytical model was developed to calculate the ultimate moment capacity of the web-bonded FRP sections considering FRP rupture and tension failure modes. Design charts were also developed for use by practicing engineers. All specimens were then analysed by nonlinear finite element software ANSYS in order to calibrate the results obtained from the experiments.