Strengthen behaviour of reinforcing bar in CFT structures

Reinforced Concrete Filled steel Tube (RCFT) columns were made and cycling axial compression experiment was carried out. The parameters of experiment were strength of filled concrete, diameter-thickness ratio, arrangement of reinforcing bars (including little ring, bigger ring and double rings), and steel tube with or without rib. The influences of experimental parameters on mechanical performances of RCFT are described. As the result, reinforcing bars can improve the shear resistance and restrict shear failure of infilled concrete; double rings arrangement can improve the combination of steel tube and concrete; but that has no influence on the confined effect and the ductility of specimens.