Investigation of the Residual Structural Performance of Hollow Section Stub Columns Under Eccentric Axial Compression Following Fire Exposure

This study examines the residual structural performance of Hollow Section Stub Columns (HSSCs) after exposing them to high temperatures and subjecting them to eccentric axial compression, aiming to better comprehend their Post-Fire Behavior (PFB). Several Finite Element Models (FEMs) were improved and validated with experimental data for the mechanical behavior of Ultra-High-Strength Steel (UHSS) columns with different geometric and loading conditions. The study considered Cross-Sectional Shape (CSS) (circular and square), size of cross-section, Wall Thickness (WT), and eccentricities in the X-direction and Y-direction. The results showed that Circular Columns (CCs) exhibited greater Residual Strength (RS) than Square Columns (SqCs), especially under high temperatures. In addition, increasing Cross-Sectional Dimensions (CSDs) and WT improved Load Capacity (LC) and fire resistance, while increased eccentricities caused significant reductions in ultimate strength and resulted in out-of-plane deformations with complex Buckling Modes (BMs). The verified models reproduced the experimental behaviors and delineated the influence of geometric factors on Thermal Degradation (TD).