Behaviour of concrete-encased CFST columns under combined compression and bending

• A finite element analysis on concrete-encased CFST column under combined compression and bending is developed.
• Full-range response of the load versus deformation relations is analysed.
• Parametric studies are performed.
• Simplified model for the section capacity of concrete-encased CFST column under combined compression and bending is suggested.

The performance of concrete-encased CFST column under combined compression and bending is studied in this paper. A finite element analysis (FEA) model is developed to analyse the behaviour of the composite column, and generally good agreement is achieved between the measured and predicted results in terms of the failure mode, the load-deformation relation and the ultimate load. Typical failure modes, full-range response of load-lateral deflection relation, loading distributions of the inner CFST and the outer RC components, the contact stress between the steel tube and the concrete of the composite columns are analysed. The influence of slenderness ratio and loading paths on the composite columns are also investigated. Influence of parameters, such as the strength of concrete and steel, steel ratio of CFST, longitudinal bar ratio and diameter of CFST on the sectional capacity of the concrete-encased CSFT columns is analysed based on the FEA model. A simplified model is proposed to calculate the sectional capacity of concrete-encased CFST columns under combined compression and bending.