Study on behavior of twin-column RCFT pier under horizontal cycling load

Concrete Filled steel Tube (CFT) is Well known because of its excellent mechanical performances. If the combination of the steel tube and concrete is promoted, the performances increase with a leap. The authors have studied Reinforced Concrete Filled steel Tube (RCFT) that is filled Reinforced Concrete (RC) into a steel tube, to get better performances. In this study, twin-column RCFT piers were made; experiment under horizontal cycling load was carried out. The parameters of experiment were strength of filled concrete, diameterthickness ratio, arrangement of reinforcing bars, and steel tube with or without rib. In this paper, the influences by experimental parameters to mechanical performances of RCFT are described. As the result, the performances on strength and deformation of RCFT piers are better than CFT piers.