New Formulations for the Cross-Sectional Strength of High-Strength Steel Rectangular and Square Hollow Sections Using a Generalized Slenderness-Based Resistance Method

Light-weight spatial structures with high demands for aesthetics and structural strength and stability are increasingly being built using high-strength steel (HSS) rectangular hollow sections (RHS) or square hollow sections (SHS). Currently, their use is partly hindered by an underlying overconservatism in local buckling design rules, since most HSS sections are slender with regards to local buckling. This paper illustrates a novel approach for the design of thin- to thick-walled RHS and SHS against elastic and elasto-plastic local buckling. It introduces a ""Generalized Slenderness-based Resistance Method"" (GSRM), which was developed over the course of an extensive, multinational and EU-funded research project - HOLLOSSTAB (2016-2019). The method further generalizes advanced cross-sectional definitions of local and global slenderness, ultimately providing a strength-based resistance approach that generalizes the concepts of established design methods such as the Direct Stength Method. In the GSRM, the slenderness and buckling resistance are both based on the section elastic resistance and incorporate the overall applied load case. This new format is used as the basis for the derivation of new design rules, which were developed through an extensive parametric study and mechanical model calibration.

The presented study also includes an analysis of the underlying level of the reliability of the GSRM design rules and compares its advantages over conventional design methods for HSS SHS and RHS, especially for slender cross-sections loaded by general direct stresses caused by compression and arbitrary bi-axial bending.

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