Strength of short concrete filled high strength steel box columns

Abstract

The use of concrete filled steel box columns has been consistently applied in the design of tall buildings as they provide considerable economy in comparison with conventional steel columns. Their use allows the adoption of steel or composite floor systems combined with economically constructed columns. The use of these columns also has considerable advantages over reinforced concrete columns as they allow higher percentages of reinforcement to be adopted. In basements of tall buildings where car park space is of premium cost, a reduction in the column size can provide significant economic benefits. The use of high strength steel can be applied in these situations. This paper provides an extensive set of experiments on high strength steel box columns filled with concrete. A numerical model is presented and calibrated successfully with these tests. Furthermore, comparisons with the Eurocode 4 model for composite columns are also undertaken in this paper and this is found to be unconservative in its prediction of axial and combined strength. A mixed analysis technique is therefore presented, which treats the concrete as rigid plastic and the steel as linear elastic. This model is calibrated well with the numerical model presented and both of these models are found to be conservative in predicting the test results.