Q460C welded box-section columns under eccentric compression

The buckling behaviour of axially loaded high-strength steel (HSS) columns has been researched to extend the scope of design codes to cover higher strength steels. However, intended and unintended load eccentricity will induce bending combined with axial compression in columns. The design of HSS columns in bending and axial compression is limited due to a lack of test data and good understanding. This paper presents an experimental and numerical study on the ultimate strength of HSS columns subject to eccentric compression. Seven Q460C steel welded box-section columns with width-to-thickness ratio of 18, 12 and 8 were tested to failure. A comparison of the test strength with the design strength predicted according to current Chinese and European codes showed the conservatism of the design interaction formulae. A finite-element model with consideration of initial geometric imperfection and residual stress was developed and verified against the test results. Extensive parametric analyses were conducted to investigate the effects of slenderness, eccentric ratio and width-to-thickness ratio on the ultimate strength of eccentrically loaded columns. Finally, modifications of current design formula to include HSS box-section column in bending and axial compression were developed.