Performance of steel-reinforced square concrete-filled steel hollow section (SRSCFSHS) columns under uniaxial compression

Due to high load carrying capacity and convenience of designing column-beam connections, steel-reinforced square concrete-filled steel hollow section (SRSCFSHS) columns have been increasingly employed in the structural engineering. In this study, the mechanical behaviors of SRSCFSHS columns were numerically investigated with the software of ABAQUS/standard solver. To verify the validity of the finite element models of the composite columns, the simulation results were compared with the existing experimental results, and good agreement was achieved. According to the simulation results of SRSCFSHS columns, the encased section steel could restrain the generation or propagation of cracks in core concrete thus the composite column can obtain a higher strength and better ductility than that of normal square concrete filled steel tube (CFST) columns. Then, a total of twenty-six SRSCFSHS columns were numerically studied to examine the effect of steel tube ratio (α_t), section steel ratio (α_s), concrete strength (f_cu), yield strength of steel tube (f^t _y), yield strength of section steel (f^s _y) and the slenderness ratio (λ) on the mechanical properties of the SRSCFSHS columns under uniaxial compression. A new model was then proposed since the model in Eurocode 4 comparatively underestimated the strength of SRSCFSHS column. Based on the comparison between the calculation results from the proposed approach and experimental results, the proposed model can provide reliable prediction of the strength of SRSCFSHS columns.