Dynamic Response of Circular Concrete-filled Steel Tubular Columns under Very Low-elevation Lateral Impact Loads: Tests and Deflection Calculation Method

Abstract An experimental investigation of circular concrete-filled steel tubular (CFST) columns subjected to very low-elevation lateral impacts was performed. Six circular CFST members were prepared for lateral impact tests according to the typical CFST columns in high-speed railway stations in China. The impact location was at the height of the 2/9 column, which was determined according to the impact point between the running train and the column. There were three variables in the tests: the thickness of the steel tube, the impact velocity, and the axial load. The failure modes were determined in the tests, along with the time histories of the impact force and the deflection at the impact location. A finite-element analysis was performed to examine the effects of the axial load and scaling on the maximum deflection. According to the travelling plastic hinge theory, a three-stage rigid plastic mechanical model was employed to describe the impact process, in which the impact location was at the non-mid-span, and a calculation method for the deflection was developed. The method is generally applicable to CFST columns at any impact position. A comparison with the test results indicated that deflections can be calculated with reasonable accuracy using the proposed method.