Ultra-light gauge steel storage rack frames. Part 2 – Analysis and design considerations of second order effects.

Local and distortional buckling reduces the flexural and warping rigidities of steel frames. As a result, the sway buckling load of locally unstable unbraced frames is reduced and sway deflections increase at a faster rate than corresponding locally stable unbraced frames. This leads to greater second order moments and potentially premature collapse, since commonly, unbraced steel frames are designed using elastic analyses (2nd order or 1st order with moment amplification) which assume unreduced values of the flexural and warping rigidities. This paper investigates the effects of second order moments induced by local and/or distortional buckling of the uprights of steel storage rack frames. Using results from the accompanying experimental investigation, calibrated FE models are used to predict the strength of steel storage rack frames with increasingly slender cross-sections. The FE strengths are compared to design strength predictions and conclusions are drawn about the extent to which current specifications are able to accommodate second order moments generated by local and/or distortional buckling. [ABSTRACT FROM AUTHOR]