Global buckling behaviour of welded Q460GJ steel box columns under axial compression

This paper describes an experimental and numerical study on the global buckling behaviour of welded Q460GJ steel box columns. In the experimental programme, seven steel columns with different cross sections and wall thicknesses were tested under axial compression. The load capacity of steel columns was quantified. Comparisons were made between experimental results and design values calculated in accordance with national standards. Furthermore, numerical models were established in which initial geometric imperfections and residual stress distributions were considered. The model was validated against test data with reasonably good accuracy. A parametric study was conducted on the effects of initial geometric imperfections and normalised slenderness on the load capacity of box columns. Experimental and numerical results indicated that Q460GJ steel box columns could develop higher global buckling resistances than the values calculated from GB50017-2003 and Eurocode 3, but ANSI/AISC360-10 might not be safe for welded box columns with small width-thickness ratios. Therefore, the design approaches for conventional steel columns were modified so that the buckling behaviour of box columns fabricated of Q460GJ steel could be accurately evaluated.