Concrete-filled steel tube columns of different cross-sectional shapes under axial compression: A review

This paper presents a review on the axial compression behavior of different cross-sectional shaped concrete-filled steel tube (CFST) columns such as circular, rectangular, square, elliptical, hexagonal, octagonal and round-ended. A discussion on some special shapes like triangular, D-shape, ¼ circular, fan shape etc. is also done in this paper. Confinement offered by the varying cross-sectional shape steel tubes to concrete core, material strength limits and slenderness limits available in different codes of practices and the proposed yield slenderness limits for rectangular, elliptical and octagonal cross-sections are discussed. The failure modes encountered during the axial compression test on CFST columns are mentioned. An analysis on the parameters that influence the behavior of the columns, design equations in the current codes of practice, modifications made on the code design equations, equations proposed on the determination of compressive strength of different cross-sectional shapes of CFST columns is done. Unified formulas for two different cross-sectional shapes and solid and hollow concrete-filled steel tubes are also included. Conclusions are finally made based on the discussion done.