Studies on seismic performance of CFRP and steel bars hybrid reinforced concrete frames

The studies investigated the seismic performance of carbon fibre-reinforced polymer (CFRP) and steel bars hybrid reinforced concrete (CSRC) frames. The influences of CFRP bar replacement ratios (CBRRs) and positions (CBRPs) in the frame columns were studied. Pseudo-static tests were conducted on four frame specimens. One basic specimen was a reinforced concrete (RC) frame. The other three were CSRC frames with 23.37%, 46.75% and 58.44% of CBRRs. The test results showed the CSRC frame specimens presented remained in the failure mode of strong column-weak beam as the basic RC frame specimen. Compared with the RC frame, the maximum load carrying capacity changed negligibly, but the peak displacements significantly increased by 19.42% to 59.37%, as the CBRRs increased from 23.37% to 58.44%. The ductility, residual displacement, initial lateral stiffness and cumulative energy dissipation of CSRC frames had no obvious change as the CBRRs were less than 26.47%. As the CBRRs were larger than 46.75%, the residual drift ratios of the CSRC frames decreased by 15.22% to 20.13% at 2.00% rift ratio level, the cumulative energy dissipations of the CSRC frames decreased by 9.69–15.42% at 3.00% rift ratio level, Compared with the RC specimen. Finally, the calculation models for calculating the load carrying capacity of CSRC frames and columns were proposed. The calculated results and test results were in good agreement.