Seismic performance of ordinary RC frames retrofitted at joints by FRP sheets

This paper reports on the results of an investigation into the effectiveness of FRP retrofitting the joints in enhancing the seismic performance level and the seismic behaviour factor (RR) of ordinary RC frames. The flexural stiffness of FRP retrofitted joints of the frame is first determined using nonlinear analyses of detailed FE models of RC-joint–FRP composite. The retrofitted joint stiffness is then implemented into the FE model of the frame in order to carry out nonlinear static (pushover) analyses on the FRP retrofitted frame. The seismic performance level and RR-factor components of the retrofitted frame are then compared with those of the original frame and the same frame retrofitted with steel bracings, reported previously. The results show that the performance level and the seismic behaviour factor of the FRP retrofitted RC frame are significantly enhanced in comparison with the original frame and are comparable with those of the steel-braced frame. It is also found that using FRP at joints may upgrade an ordinary RC frame to an intermediate and even a high ductility frame.