Experimental and numerical study of L-shaped irregularly concrete-filled steel tube columns under axial compression and eccentric compression

This paper proposes a new kind of L-shaped irregularly concrete-filled steel tube column (LICFSTC), which is formed by standardized steel (I-shaped and U-shaped steel) and infilled concrete, and studies its behavior under axial and eccentric compression through experimental and numerical investigation. Compared with L-shaped CFST column proposed by previous researchers, this kind of L-ICFSTC has more convenience in installation and construction as well as excellent behavior in mechanical performance. Firstly, the experiments of two full-scale specimens under axial compression and two full-scale specimens under eccentric compression are carried out. The L-ICFSTC specimens exhibits overall stability failure mode because the rapid increase of the horizontal deflection and strain at the midspan of the specimens is observed at the time of failure. In addition, the ultimate load of the L-ICFSTC under eccentric compression is related to the eccentric direction. Secondly, the finite element (FE) models of the specimens are established to simulate the loading process of experimental specimens. The results obtained from FE models agree well with the experimental results. Thirdly, through the parameter analysis based on the FE models validated above, it is found that the height of column, length of column limb, thickness of steel tube, material strength and eccentricity have influence on the stability performance of L-ICFSTC. The experimental and FE numerical results obtained in this study could provide the reference for establishing a complete design method of the L-ICFSTC in near future.