LAUSR

Abstract The compression behavior of octagonal concrete-filled thin-walled tube (OCFT) columns was investigated. Eight OCFT columns with different tube sections were tested under monotonic compressive loading. The tests showed that the thin-walled tubes underwent elastic or inelastic local buckling, and the slenderness ratio (or width-to-thickness ratio) and section shape of the tubes significantly affected their buckling modes. Despite such local buckling, the load-deformation behavior of the OCFT columns all was highly ductile, due to confinement to the infilled concrete. The design strengths of AISC 360-16 agreed well with the test strengths. In this study, effective stress–strain relationships of the tube and infilled concrete were proposed to account for the local buckling and confinement. The maximum strength and post-buckling behavior were estimated through the strain-compatibility analysis, and the results were compared with the tests.