Structural assessment of composite seam-welded rectangular hollow columns

Structural elements made of seam-welded hollow sections are considerably less expensive than their seamless equivalents. This is a strong incentive for their use, but the current steel design standards still contain recommendations for seam-welded hollow sections based on test results performed with sections produced using outdated steel grades and fabrication processes. These design procedures are even more conservative when applied to composite tubular seam-welded elements. This paper presents an experimental campaign performed to investigate the structural behaviour of steel- and concrete-filled composite columns made with seam-welded rectangular hollow profiles. The experiments involved columns with only steel sections, concrete-filled and concrete-filled plus additional reinforcing bars. The main aim of the tests was to identify the contribution of each component in the overall structural response. The results enable an evaluation of the design recommendations present in Eurocode 4 aiming to determine less conservative buckling curves to be used for the investigated composite columns made of seam-welded rectangular hollow sections.