Study on the mechanical properties of axially loaded steel tubular columns filled with steel-reinforced high-strength concrete

A new design model for steel concrete composite columns, i.e.steel tubular column filled with steel reinforced concrete, was established. In this kind of steel concrete composite column, steel section was inserted into concrete filled steel tube. The test results of 13 axially loaded high strength concrete composite columns were presented and their mechanical behavior were studied. The results showed that the composite column has higher load bearing capacity and excellent ductility. Cracks in concrete can be put off or avoided effectively because of the existence of steel section. The ultimate bearing capacity and ductility of the composite column decrease with the increase of slenderness ratio. Based on the test results, formulas for predicting the ultimate bearing capacity of the composite column are proposed.