A new calculation method for axial load capacity of separated concrete-filled steel tubes based on limit equilibrium theory

A new calculation method for axial load capacity of separated concrete-filled steel tubes based on limit equilibrium theory was proposed, which took into account the decrease of confinement effect by steel tube and the non-uniform distribution of ultimate stress in cored concrete. The accuracy of the analytical result is validated through running the numerical result by finite element method (FEM) and experimental data as well. The influences of the key parameters on the load capacity of the concrete-filled steel tube (CFST) was studied, including the separation ratio, concrete compressive strength, and steel strength. The results indicate that the load capacity of the tube increases with concrete strength and steel strength under the separation ratio less than 4%, while decreases with a higher separation ratio improved.