Overall stability behavior of axially compressed cold-formed thick-walled steel tubes

This research is focused on the overall stability of axially compressed cold-formed thick-walled square and rectangular steel tubes, which is generally represented by the column curve. An experimental study on axially compressed pin-ended columns was conducted to investigate the failure mode and overall stability. Then, further parametric finite element analysis was conducted to get more data. Also, a comparison between the test and FEA data and the column curves in different codes, including the Chinese codes and North American specifications, was presented in this paper. It was found that the column curves in Technical code of cold-formed thin-walled steel structures (GB50018-2002) and AISI S100-2016 were not suitable for thick-walled steel members. Subsequently, a fitted curve and corresponding calculation formula for stability coefficient was proposed separately for Q235 and Q345 cold-formed thick-walled square and rectangular steel tubes. Finally, the tangent modulus curves were compared with the test and FEA results and the fitted curves. It was found that the fitted curves were in better agreement with the corresponding test and FEA results while the tangent modulus curves were unconservative.