Local buckling tests of concrete-filled steel tubular columns

An experimental study on the strength of concrete-filled steel box columns has been carried out in two types of loading method. One is the local buckling test of outer plates, where axial force is applied only to the outer steel plates. The width-to-thickness ratio of the component plate is varied in 4 values. The experimental maximum strength of the steel tubes were found to be plotted between the theoretical strength curve for a hinged-hinged plate and that for a clamped-clamped plate. Another is the ultimate strength test, where axial force applied to both the inner concrete and the outer steel tube. The results show that the maximum strength of concrete-filled steel tubular columns can be estimated by the sum of the local buckling strength of steel tube and strength of confined concrete.