Abstract：A new type of circular concretefilled slotted steel tubular structure was proposed. Monotonic axial compression tests were carried out on six concretefilled slotted steel tubular columns and six common concretefilled steel tubular columns. The test results show that the slots can reduce the folding and buckling phenomena when the thickness of steel tube is small. The failure modes of concretefilled steel tubular columns and concretefilled slotted steel tubular columns are showed with remarkable dilation in midheight when the thickness of steel tube is large. The slots of the steel tube have significant effect on the bearing capacity of smaller thickness of steel tube, and the bearing capacity of the concretefilled slotted steel tubular columns is approximately 1.1 to 1.3 times of that of the common concretefilled steel tubular columns. With the increasing of steel tube thickness, the ultimate load ratios of concretefilled slotted steel tubular columns and common concretefilled steel tubular columns are gradually decreased. The slots provide a local structure for the centralized release of deformation of concrete filled steel tubular columns under axial compression, which can avoid the longitudinal buckling of the steel tube effectively. Considering the influence of confinement efficiency of steel tube, the unified method for calculating the bearing capacity of circular concretefilled steel tubular under axial compression with different structures is proposed, and the predicted results are more conservative than the experimental values.
