Axial behavior of concrete-filled double-skin corrugated steel tubular columns

Abstract:

To enhance the service and mechanical performance of hollow reinforced concrete (HRC), this study introduces a novel composite column, named concrete-filled double-skin corrugated steel tube (CFDCST). This paper conducted a total of 4 large-size CFDCST short columns and 2 HRC short columns, and the main parameters of the test were the type of specimen and the type of outer corrugated steel tube (CST). The failure modes were analyzed and the key mechanical indicators such as the load-bearing capacity, peak strain, and ductility coefficient of the specimens under different parameters were compared and analyzed. The load-CST strain curves were obtained to reveal the confinement mechanism and verify the influence of the outer CST types. The results show that the outer CST can provide confinement to the sandwiched concrete and the smaller the helical angle, the larger the confinement effect. The inner CST primarily offers effective support for unconfined inner concrete wall to preserve the integrity of the cross-section. When the nominal confinement factor and the hollow ratio were basically similar, due to the slippage of the lock-seam, the peak stress, peak strain, and ductility coefficient of CFDCST columns with large helical angle were 15.5%, 21.8% and 16.7% lower than those of CFDCST columns with small helical angle, respectively. When the total steel ratio was basically similar, the load-bearing capacity, peak strain, and ductility coefficient of the CFDCST columns with small helical angle were 10.6%, 36.2% and 50.0% higher than those of HRC columns. Finally, based on the test results, the applicability of 3 typical bearing-capacity formulas was assessed and the corresponding design recommendations were given subsequently.