Stability of slender concrete-filled steel tubular X-column under axial compression

Abstract Concrete-filled steel tubular X-column (CFST X-column) is a novel structural member, which is of potential in the diagrid structural systems and cooling tower support systems. In this paper, the stability of slender CFST X-column is experimentally and numerically investigated. Firstly, three slender CFST X-columns are constructed and tested subjected to axial compression. The failure modes and load–deformation curves of slender CFST X-columns are respectively recorded during these tests and comprehensively analysed. An ABAQUS finite element model (FE model) is established and verified according to the experimental observation. Then, the full-range load versus deformation relationships as well as the stress development in concrete and steel tube are comprehensively studied to reveal the mechanical mechanism of the proposed structure. Further, parametric studies are conducted to learn the influence of parameters on stability, including material strength and geometric parameters, etc. Finally, the calculation of stability bearing capacity is discussed. A modified design approach is developed specifically for slender CFST X-columns under axial compression and shown to yield conservative and safe resistance predictions by comparing against the test and FE model results.