Flexural–torsional buckling of ultra light-gauge steel storage rack uprights

• Sixteen axial compression tests on ultra-light gauge steel storage rack members conducted.
• Combined effects of interactive buckling between local, distortional and flexural–torsional modes investigated.
• Imperfections, ultimate loads, failure modes and deformations for all tests were captured.
• Three International standards evaluated based on experimental results.
• EN 15512 [3] determined to capture interactive buckling more accurately than AS/NZS 4084 [1] and RMI [2].

This paper presents an experimental investigation into the behaviour of ultra light-gauge steel storage rack uprights subjected to compression. Two different types of members with varying lengths are tested and while the combined effects of local and distortional buckling are investigated, special attention is given to longer specimens that fail by flexural–torsional buckling in combination with local and distortional buckling. Deformations experienced during testing by all of the specimens were measured and observations regarding failure modes have been documented. In addition, the geometric imperfections of each member were measured before testing, as were the material properties of the cold-rolled sections and the virgin steel from which the sections were formed. This paper details the observed failure modes, the recorded ultimate strengths and the load-deflection responses. Design capacities calculated from AS/NZS 4084 (2012) [1], RMI (2012) [2] and EN 15512 (2009) [3] specifications are then evaluated and compared to the experimental results obtained.The evaluation of international specificationsdetermined that EN 15512 (2009) [3] is more accurate in predicting ultimate loads of sections undergoing interactive buckling than both AS/NZS 4804 (2012) [1] and RMI (2012) [2].