Experimental study on steel beam–columns composed of slender H-sections under cyclic bending

• Cyclic test on six H-section beam–columns with large width-to-thickness ratios
• Specimens exhibited limited strength but certain plastic deformability.
• The flange and web interaction effects are proved.
• A new method for ultimate strength is proposed.

This paper presents an experimental study of six H-section steel beam–columns with large width-to-thickness ratios subjected to combined constant axial force and cyclic bending moment about the strong-axis. Considering different categories of cross-sections, various width-to-thickness ratios of the flange and web of the specimens were selected, and a reliable structural testing system was employed. The test results showed that, for all the specimens, local buckling was the dominating failure mode. Due to their relatively large width-to-thickness ratios of the flange and web, the H-section specimens exhibited limited resisting strength but certain plastic deformation capacity as well as energy dissipation capacity, encouraging employment of such members in seismic areas. It was also found that the flange width-to-thickness ratio and the axial force ratio have significant effects on the hysteretic behavior. In addition, a modified plastic effective width method for ultimate strength was proposed.