Experimental study on the strength and ductility of steel tubular columns filled with steel-reinforced concrete

The steel tubular column filled with steel-reinforced concrete is formed by inserting a steel section into a concrete-filled steel tube. The objective of this study is to investigate the strength and ductility of composite columns subjected to axial compressive loads. For this purpose, an experimental study was conducted for 16 composite columns. The main test parameters were the concrete strength, the confinement index (θ), the structural steel index (ρ) and the length-to-diameter ratio. From test results, the strength and deformation characteristics of these composite columns were reported. The results showed that composite columns had very high strength, ductility and capacity of energy absorption because of the interaction between the steel tube, steel section and concrete. Formulas for the prediction of the ultimate strength of the composite column were also proposed in this paper, and calculated results are in good agreement with test results.