Seismic performance of RC frames joints retrofitted by CFRP composites

The relocation of the plastic hinges from the vicinity of the joint more towards thebeams is an appropriate approach to increase the performance of the joint and also the structure. One ofthe methods to attain this aim is strengthening the joint with FRP material. Joints in real structures dealwith some limitation, such as sides beams which is connected to the joints at the floor level. Theseconditions make some problems to strengthen the joints. Therefore, the configuration of FRPapplication is considered in the form of L-shaped at the top and bottom beam, wrapping for beam andwrapping for the columns. This paper reports on the results of an evaluation into the effectiveness ofFRP strengthening the joints in enhancement of load carrying capacity and ductility capacity of theframe. The additional flexural stiffness generated by FRP is calculated comparing the moment-rotationof the FRP retrofitted and the original joints obtained from the finite element analysis. It is thenimplemented into a numerical model for the strengthened frame and using nonlinear static analysismethod, the original frame and strengthened frame are analyzed. The nonlinear results confirm aconsiderable increase in the lateral load carrying capacity and ductility capacity. Also, predicteddamage confirms the relocation of the plastic hinges from the vicinity of the joint more towards thebeams.

Keywords:

Beam–column joint , FRP scheme , plastic hinge relocation , moment-rotation , and pushover analysis