Abstract: The load versus deformation curves of steel tube confined concere members under pure bending are carried out using finite element analysis. The calculated results are verified by test results from two circular and two square specimens, and reasonable agreement is demonstrated. The finite element analysis modelling is then used to analyze the load versus deformation relationships, and to investigate the composite action between the steel tube and concrete core. A simple formula for calculating the ultimate strength of the composite members under pure bending is recommended.