Buckling Resistance of Concrete‐Encased Composite Columns with Heavy Hot‐Rolled Profiles

Abstract

This paper presents GMNIA‐based (geometrical and material nonlinear analysis with imperfections) parametric results for concrete‐encased composite columns using heavy hot‐rolled steel profiles with thick flanges. Six representative HL, HD, and UB sections with flange thicknesses ranging from approximately 40 mm to the highest available value on the market are analysed. The study considers 240 column cases covering variations in steel‐section profiles, material grades, column lengths, reinforcement ratios, residual stresses, and geometric imperfections. GMNIA‐derived column buckling resistances are converted into reduction factors using the overall partial factor defined by the General Method in EN 1994‐1‐1, enabling verification of the buckling‐curve choices used in the Simplified Method. The results show that the buckling‐curve selections in the Simplified Method remain valid for heavy profiles with thick flanges, with a recommended curve reduction for high h/b ratios (e.g., 2.4). The findings provide background information supporting the extension of the Simplified Method to hot‐rolled profiles with flange thicknesses above 80 mm, and to those above 40 mm when combined with high h/b ratios.