Preliminary Numerical Investigation on Eccentric Compression Behavior and Bearing Capacity Correction Framework of T-Shaped Steel Tube-Steel Reinforced Concrete Columns

This paper presents a preliminary numerical investigation on the mechanical behavior under eccentric compression of T-shaped steel tube-steel reinforced concrete columns. A refined finite element (FE) model was developed in ABAQUS 2021 and validated against published axial compression test results. The effects of three key parameters (eccentricity, outer steel tube thickness, and built-in steel skeleton size) on the bearing capacity, failure mode, stiffness degradation, and stress distribution of the studied members were systematically analyzed via finite element analysis, followed by comparative calculations and an applicability analysis of the calculation of eccentric compression bearing capacity. All eccentric compression results presented herein were obtained through numerical simulation and have not been directly verified by physical tests. The results show that the ultimate bearing capacity decreases by more than 57% as the eccentricity increases from 0 mm to 75 mm, with the failure mode transitioning from axial compression failure to flexural failure. Within the studied parameter range, the 4 mm-thick outer steel tube exhibits superior comprehensive performance, including bearing capacity, stiffness, and ductility. Increasing the built-in steel skeleton size effectively enhances the flexural stiffness and ductility, and delays stiffness degradation. The existing code-specified formula demonstrates good accuracy (relative error < 6%) for e ≤ 50 mm but yields significant errors for e = 75 mm. An empirical expression for the equivalent eccentricity influence coefficient α is proposed, which reduces the overall average error from 4.89% to 2.26% within the parameter scope of this study.