Strength of concrete filled steel box columns incorporating local buckling

Concrete filled steel box columns have recently experienced a renaissance in their use throughout the world. This has occurred due to the significant advantages that the construction method can provide. This paper deals with the strength behavior of short columns under the combined actions of axial compression and bending moment. The paper addresses the effect of steel plate slenderness limits on this behavior. An extensive set of experiments has been carried out and a numerical model developed elsewhere is augmented and calibrated with these results. A simple model for the determination of the strength-interaction diagram is also verified against both the test results and the numerical model developed in this paper. This model, based on the rigid plastic method of analysis, is existent in international codes of practice, but does not account for the effects of local buckling, which are found to be significant with large plate slenderness values, particularly for large values of axial force. Thus some suggested modifications are proposed to allow for the inclusion of slender plated columns in design.