Experimental study on eccentric compressive behaviors of 6061-T6 aluminum tubular long columns filled with concrete

In this paper, eccentric compressive experiments of 12 circular and 6 square concrete-filled 6061-T6 aluminum tubular (CFAT) long columns were carried out. The influence of the section form, thickness of aluminum tube, slenderness ratio, and eccentricity on the flexural performance of CFAT long columns was investigated. The results showed that all the specimens exhibited flexural-dominated failure. The variation of eccentricity had little impact on the overall failure mode of the aluminum tube, while it dramatically influenced the failure mode of the internal concrete. The internal concrete failed in concrete crushing for all the square columns, while it remained intact for the circular columns. This indicates that circular tubes provide a better constraint effect on the internal concrete, there by increasing the ultimate strain of concrete under compression. It was also found that the increase of eccentricity leads to the weakening of the confinement afforded to the internal concrete, while the increase of slenderness ratio has no obvious effect on the restraining effect. Finally, the applicability of current design provisions for concrete-filled steel tubular (CFST) long columns to CFAT long columns was evaluated, and design suggestions were proposed.