Mechanical Behavior Analysis of Reinforced Hollow High Strength Concrete Filled Circular Steel Tubular Short Columns under Axial Loads
A novel composite column of reinforced hollow circular steel tubes filled with high-strength concrete(RHCFST)is proposed,and its mechanical behavior under axial load is investigated.The aim of this study is to address the issues of large hollow ratio and poor ductility commonly observed in hollow concrete-filled steel tubular(HCFST)columns.Experimental testing was conducted on reinforced hollow circular high-strength concrete-filled steel tubular short columns subjected to axial load.Subsequently,a finite element model of the composite column was developed using ABAQUS software,and its accuracy was validated against experimental data.The mechanical behavior of the composite column was analyzed,with a particular focus on the stress distribution under axial load,the distribution of internal forces among different components,and the overall stress state.Comparative analysis revealed that improvements were observed in the RHCFST columns compared to the HCFST columns,with the ultimate bearing capacity increasing by 6.37%for specimens without ordinary steel bars and by 13.31%for specimens with ordinary steel bars.Additionally,notable enhancements were observed in the ductility index(DI)and strength index(SI).Throughout the loading process,the proportions of internal forces carried by the column concrete and the sandwich concrete were determinedto be 36.2%～39.7%and 29.0%～30.6%,respectively.The proposed RHCFST columns,particularly those incorporating ordinary steel bars,demonstrated superior bearing capacity and ductility.Notably,sandwich concrete and column concrete were identified as the primary load-bearing components during loading,while the steel bars remained inactive in bearing internal forces during the initial loading stages,only becoming effective during the plastic strengthening phase.
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