Thin-Walled Steel Tubes Filled with High Strength Concrete in Bending

Concrete filled steel tubes are efficient members in structural applications including bridges, buildings and piled foundations. Their design has been based on theory and tests on columns under load applied axially or at relatively small eccentricities. For other cases, their design has been extrapolated due to little research. The effects of both local buckling of thin walled steel tubes and the confined concrete in flexure have not been adequately examined. This paper focuses on numerical studies carried out to determine the significance of factors such as initial imperfections and the confined concrete. These results are being used to design an extensive experimental program that will be used to develop safe economical design rules which can be directly included in the Australian Standard for Composite Structures currently under development.