Experimental research on mechanical behavior of concrete-filled thin-walled stiffened square steel tubular short column under axial load

In order to research the mechanical properties of thin-walled concrete-filled square tubular short columns under axial compression, 26 thin-walled concrete-filled square steel tubular short columns with different width to thickness ratios of the steel tube, heights and numbers of stiffeners were tested. The results show that the walls are curved before reaching the bearing capacity for the concrete-filled square tubular columns without ribs, and the greater the width to thickness ratio of specimen, the sooner the drums occur, the sooner the steel tubular section of drum position fails, which is a disadvantage for concrete-filled steel tube. The mechanical properties of the concrete-filled thin-walled square steel tubular short columns with stiffened ribs are obviously improved; the local drums of steel tubular walls are slowed down, the material strength is fully utilized;and the bearing capacity of specimen is improved.When the width to thickness ratio of specimen is 60 or 80, the height of the stiffener has the greatest influence on the bearing capacity;the higher the height of the stiffener, the greater the bearing capacity. The increase of the stiffener number has little effect on the bearing capacity. When the width to thickness ratio is 100, the setting of a single stiffener cannot meet the bending stiffness requirements of the local buckling of the tube wall, so it is necessary to increase the number of stiffeners to increase the support point of the restrained deformation for steel tube,to reduce the local buckling, and to improve the local buckling critical load of the specimen. At the same time, ABAQUS finite element calculation software is used to calculate the whole mechanical process of the thin-walled concrete-filled square tubular short columns with stiffeners. The experimental results are compared with the finite element simulation results, which can lay the foundation for the next analysis.