Axial compressive behavior of concrete-filled aluminum alloy circular tubular stub columns with in-built H-steel

Current research on aluminum alloy composite structures primarily focuses on concrete-filled CFRP aluminum alloy tubular columns, and studies on aluminum alloy-steel-concrete composite columns have been scarce. The aim of this study was to investigate axial compressive behavior of concrete-filled aluminum alloy circular tubular stub columns with in-built H-steel through axial compression experiments and the finite element (FE) method. Eight stub columns were used in the experiments, with the internal core concrete type and H-steel content taken as variation parameters. Analysis revealed that the location of the bulging failure of the specimen was influenced by the internal core concrete type. The aluminum alloy tube and H-steel exhibited good deformation coordination under axial compression. Parametric analysis showed that the in-built H-steel can effectively inhibit the transverse deformation of concrete and delay the damage of stub column specimens. When the same type of concrete was used, the axial compression capacity, axial compressive stiffness, and energy absorption of the columns increased with the increase in steel content. When the steel content was maintained, the specimens with lightweight concrete exhibited higher bearing capacity and axial compressive stiffness. For energy absorption behaviors, the specimens with lightweight concrete and steel content of 8.76% exhibited superior performance. An expanded parameter analysis was conducted utilizing the FE method. Based on the results, a bearing capacity calculation formula for the composite columns was proposed using the superposition theory. The findings of this study can help address the durability issues of steel-concrete and aluminum alloy-concrete members and thus improve structural performance.