Numerical investigation on the global stability of welded high-strength steel columns with flame-cut flange edges under axial compression

Abstract

Existing studies on high-strength steel (HSS) column stability have mainly focused on rolled or conventionally welded members. The effect of flame-cut flanges and the associated residual stress distributions on the global buckling resistance of welded I-sections remains insufficiently quantified in current design standards. This study investigates the global buckling behavior of welded HSS I-section columns with flame-cut flanges under axial compression using finite element analysis accounting for geometric and material nonlinearities, residual stresses, and initial imperfections. Parametric studies were conducted on 460 MPa and 690 MPa steels across a range of slenderness ratios and cross-sectional dimensions. The results were used to assess existing design curves and propose refined formulations for more accurate stability predictions. Comparison with ANSI/AISC 360-16 and EN 1993-1-1 shows that Eurocode curves are generally conservative, while the AISC curve agrees well for normalized slenderness up to 1.5, though it overestimates minor-axis buckling capacity for 460 MPa columns. Three new design curves were calibrated using finite element results, showing improved accuracy in predicting buckling behavior. These findings provide a basis for developing more reliable and less conservative design provisions for HSS columns.