Abstract:To improve the axial performance of concrete-filled double-skin steel tubular(CFDST) stub columns, a novel thin-walled multi-cavity concrete-filled double-skin tubular(MCFDST) stub column was proposed. Experimental investigations were conducted to evaluate the axial compressive behavior of these columns. A total of fifteen MCFDST stub columns and three CFDST stub columns were designed and fabricated, with four key parameters examined: concrete compressive strength(CCS), width-to-thickness ratio(WTR) of the outer tube, hollow ratio(HR), and the presence of tensile ribs. The study assessed deformation, load-displacement behavior, damage patterns, and ductility coefficient to determine the ultimate bearing capacity, failure mode, and ductility performance of the columns. Experimental results show that increasing the CCS from 58 MPa to 90 MPa enhances the bearing capacity by 46%, while reducing the ductility coefficient by 74%. A decrease in WTR from 39 to 29 results in a 12.5% improvement in bearing capacity alongside a notable increase in ductility coefficient. The HR increase from 0.31 to 0.38 yields marginal improvements in bearing capacity(1.3%) and ductility coefficient(1.0%). Notably, the presence of tensile ribs significantly increases the bearing capacity and ductility coefficient by 14.2% and 282%, respectively. Moreover, the experimental data validated the effectiveness and accuracy of numerical modeling, which facilitated extensive finite element parameter analyses. The applicability of current design methods for predicting axial bearing capacity was also discussed, indicating that the prediction formula in Japanese standard AIJ is suitable for estimating the axial compressive bearing capacity of MCFDST stub columns.