Performance of innovative fabricated long hollow columns under axial compression

Fabricated sections are a convenient option for structures or structural elements in demand of very high strength capacities for which conventional hot-rolled and cold-formed elements with limited sizes are inadequate. When it comes to the design of compressive members, buckling is a critical design provision. In this paper the compressive and buckling behavior of an innovative long column is described. The proposed innovative fabricated columns consist of mild steel plates which are welded to mild steel tubes at corners. Experimental tests are conducted on one, two and three-meter columns whilst a robust finite element model is also developed which is validated against the results obtained from the experiments. Detailed focus is brought to the effect of fabrication imperfections, type of welding and residual stresses on the behavior of the proposed long hollow columns in test result analysis and the finite element modeling. The examined innovative column specimens are shown to exhibit superior compressive behavior since the interaction between section's plates and tubes leads to a significant increase in both strength and ductility. In addition to the structural benefit, the production cost of these columns is estimated which also justifies its advantage compared to the equivalent welded box sections in an economic point of view.