Behavior and Design of Normal- and High-Strength Steel SHS and RHS Columns

The behavior and design of hot-rolled and cold-formed steel square and rectangular hollow section (SHS and RHS) columns, made of both normal- and high-strength material, are addressed in this paper. A series of experiments on hot-rolled high-strength steel SHS columns was first conducted—six tests on S690 SHS 100×100×4 columns and six tests on S770 SHS 120×120×6.3 columns were performed. Finite-element (FE) models were developed to replicate the experimental results and to carry out parametric studies to expand the column buckling data pool. The accuracy of the European and North American buckling design rules for normal- and high-strength steel SHS and RHS columns was evaluated through comparisons with the freshly generated test and FE results, as well as with existing test data collected from the literature. Finally, a modified approach was proposed and statistically verified in accordance with existing standards; the new approach features an imperfection factor that is a continuous function of yield strength, reflecting the reducing relative influence of residual stresses and global imperfections with increasing steel grades. Improved consistency in resistance predictions over the existing design provisions is demonstrated across a wide range of steel grades and relative slenderness values.