Performance of square hollow steel-reinforced concrete composite stub columns under axial compression

Abstract

The new type of steel–concrete composite member, i.e. the hollow steel-reinforced concrete (HSRC) composite column, is proposed to improve the mechanical properties of hollow reinforced concrete (RC) members. In this study, the ABAQUS software is used to establish a finite element model (FEM) and analyze the axial compression performance of the HSRC composite stub column. The reliability of the FEM is verified by the experimental data. Then, the full range analysis on the load versus deformation relation of the typical specimen is presented, and the contact stresses on the interface between the outer RC and the inner steel tube are analyzed. Based on these analyses, the material and geometric parameters that affect the axial compression performance are investigated to determine the key factors influencing the contact stress. Finally, the contribution of the contact stress to the axial bearing capacity is quantified, and a simplified design method for the axial bearing capacity of the HSRC composite stub column is proposed. The results show that the FEM based on the ABAQUS software in which material nonlinearity is considered, can effectively predict the axial compression performance of the proposed the HSRC composite stub columns. The maximum difference between predicted and experimental data is 18.4%. The results also show that the contact stress has a significant effect on the axial bearing capacity of the HSRC composite stub columns, which increases with the increase of the steel ratio and the decrease of the hollow ratio. In addition, it was found that the axial compression bearing capacity of HSRC composite stub columns can be effectively predicted by introducing an enhancement coefficient of concrete strength, which is influenced by the hollow ratio, the steel ratio, the yield strength of the steel tube, and strength of the concrete.