Distortional buckling formulae for cold-formed steel rack-section members

The paper derives, validates and illustrates the application of GBT-based formulae to estimate distortional critical lengths and bifurcation stress resultants in cold-formed steel rack-section columns, beam and beam-columns with arbitrarily inclined mid-stiffeners and four support conditions. After a brief review ofrnthe Generalised Beam Theory (GBT) basics, the main concepts and procedures employed to obtain the formulae are addressed. Then, the GBT-based estimates are compared with exact results and, when possible, also with values yielded by formulae due to Lau and Hancock, Hancock and Teng et al. A few remarks onrnnovel aspects of the rack-section beam-column distortional buckling behaviour, unveiled by the GBT-based approach, are also included.