Ultimate strength of H-sections under combined compression and uniaxial bending considering plate interaction

The ultimate strength and behavior of steel H-sections are investigated experimentally and theoretically in this paper. The main considered parameters include different combinations of flange and web width-to-thickness ratios and varying axial force ratios, with both major and minor axis bending responses being examined. It is found that the section behavior, including occurrence of local buckling, stress distribution form after buckling and ultimate strength, is strongly dependent on the interaction between flange and web. The “plastic effective width” method (PEM) for the ultimate moment resistance of H-sections bent about strong or weak axis is refined and improved using an adjustment factor, namely cross-section slenderness, which accounts for the interactive effect of the plates under different loading conditions. Finally, PEM is proved to provide satisfactory predictions for H-sections over a spectrum of web and flange width-to-thickness ratios and axial force ratios for both the strong and weak axis bending.