Design of cold-formed high strength steel square and rectangular hollow section beam-columns

Cold-formed high strength steel (CFHSS) square and rectangular hollow section (SHS and RHS) beam-columns were investigated in this study with an objective to evaluate the applicability of existing design rules given in American, Australian and European codes for SHS and RHS beam-columns of S700, S900 and S1100 steel grades, and subsequently, provide economical and reliable design rule for CFHSS SHS and RHS beam-columns. A comprehensive numerical investigation was performed in this study, where the values of flat width-to-thickness ratio of the tubular sections ranged from 7.5 to 96. The constitutive model developed for CFHSS tubular members was used in the numerical investigation. Global and local geometric imperfections were also included in the numerical models. In total, 465 data were compared with the nominal capacities predicted from American, Australian and European codes, including 390 numerical data obtained in this investigation. The safety levels of design rules given in these standards were examined by performing a reliability analysis. It has been demonstrated that the current design rules given in the American, Australian and European codes provide conservative predictions. A modified design method based on the recommendations given in European code was proposed in this study. Overall, it has been proved that the proposed design rule provides accurate and reliable predictions for the design of cold-formed S700, S900 and S1100 steel grades SHS and RHS beam-columns.

Automated summary

In this study, the applicability of existing design rules for cold-formed high strength steel (CFHSS) square and rectangular hollow section (SHS and RHS) beam-columns was evaluated. Numerical investigation and reliability analysis were conducted, and it was found that the current design rules given in American, Australian, and European codes provide conservative predictions. A modified design method based on the European code recommendations was proposed, which was proved to provide accurate and reliable predictions for the design of CFHSS SHS and RHS beam-columns of S700, S900 and S1100 steel grades.