Behaviour of multi‐cell composite T-shaped concrete-filled steel tubular columns under axial compression

• The multi-cell composite T-shaped concrete-filled steel tubular (MT-CFST) columns are proposed.
• Experiments with 13 short columns and 12 slender columns subjected to axial loads are conducted.
• The behaviour of both short and slender MT-CFST columns under axial compression is investigated.
• Experimental results are compared with predicated results using existing design methods.

To improve the behaviour of conventional T-shaped concrete-filled steel tubular (CFST) columns, multi-cell composite T-shaped concrete-filled steel tubular (MT-CFST) columns are proposed in this paper. Experimental study of 25MT-CFST columns, including 13 short specimens with various cross sections and material properties and 12 slender specimens with different slenderness ratios, subjected to axial loads was conducted. The failure modes, axial load–strain curves for short specimens and axial load–lateral deflection curves for slender specimens were investigated. The test results were compared with design approaches for conventional CFST columns presented in Eurocode 4, AISC specification, Australian standard AS51006, Chinese code CECS159, and Hong Kong steel code, and it was found that all the design codes underestimate the bearing capacity of both short and slender MT-CFST columns to some extent.