An analytical model for thin-walled steel box columns with concrete in-fill

Concrete-filled steel box columns are widely used as a major structural element in tall buildings as they provide efficient structural performance in resisting axial compression. Local buckling of steel plates is a common failure criteria when plate slenderness ratio is large in box sections. A method using an effective width principle is proposed in this paper to predict the behaviour and load carrying capacity of thin-walled steel tubes with concrete in-fill. The present investigation addresses columns pinned at their ends and subjected to biaxial loading. Columns tested by other researchers have been analysed using the proposed method and the predicted results are compared with the corresponding test results. The proposed model is also verified against Eurocode 4. The comparison shows that the method could predict the ultimate load with sufficient accuracy.