Behaviour and design of hollow and concrete-filled spiral welded steel tube columns subjected to axial compression

Spiral welded tube (SWT) structures have found worldwide application in pipeline construction, wind turbine towers, foundation piles, and columns in tall buildings. However, the understanding of their fundamental behaviour is still insufficient and efficient analysis and design methods have not been precisely developed owing to the lack of experimental and numerical research on these types of structures. A distinct advantage of SWT is their streamlined manufacturing process, so that today large diameter SWT can be economically produced. Due to the application of SWT as structural members being relatively new, this paper presents an investigation into the behaviour of hollow and concrete-filled steel SWT columns when subjected to axial compressive loading. Parameters of particular interest affecting the strength and failure modes include the weld's spiral geometry and initial imperfections from the production process. To evaluate the behaviour of SWT columns, an accurately developed finite element model (FEM) which incorporates the effects of initial local imperfections and residual stresses using the commercial finite element program ABAQUS has been prepared. The FEM buckling behaviour of SWT is compared with that of longitudinally welded tubes (LWTs). Experimental laboratory testing is carried out on twenty columns under displacement-controlled loading conditions in order to calibrate and verify the accuracy of the model results. Furthermore, a design model is proposed for circular concrete-filled steel tube columns. In addition, comparisons with the prediction of axial load capacity using the proposed design model, Australian Standards, Eurocode, and American Institute of Steel Construction code provisions for hollow and concrete-filled SWT and LWT columns is also carried out.