Abstract:In order to deeply analyze the seismic structural measures and the formation mechanism of plastic hinge at the end of concrete-filled square steel tubular columns with stiffeners, a three-dimensional solid finite element model is established and verified with the test results. The finite element(FE) results are in good agreement with the test results. On this basis, 30 full-scale models were further established to analyze the influence of parameters such as axial compression ratio, stiffener ratio and stiffener height on column bearing capacity, ductility and plastic energy consumption. Seismic structural measures such as reasonable stiffener ratio and stiffener height of columns under different axial compression ratios and the determination method of plastic hinge are proposed. The results show. When the stiffener ratio increases, the bearing capacity, ductility and total plastic energy consumption of the column increase significantly, the plastic energy consumption of stiffeners increases, while the plastic energy consumption of concrete decreases, which has little effect on the steel tube. When the axial compression ratio is 0.2, the bearing capacity of the column is not significantly reduced and the ductility is better, so stiffeners can be omitted, when the axial compression ratio is 0.5 and 0.8, the reasonable stiffener ratio is 0.2 and 0.4, respectively, and the stiffener height is respectively 1 000 mm, 1 500 mm. When the longitudinal compressive strain of the steel tube reaches 4 times the yield strain, plastic hinges appear at the end of the column, a plastic hinge length formula considering the axial compression ratio and stiffener ratio is further proposed, the calculation results of the formula and the FE results are less discrete.