Research on Design Method of Axial Compressive Capacity of Circular CFST Slender Columns

Abstract

With the emergence of large-span spatial structures and high-rise buildings, circular concrete filled steel tubular (CFST) slender columns are necessary to be used in practical projects. In order to discuss the calculation method of the axial compressive strength of circular CFST long columns, especially slender columns, three codes of EC4, AISC and AIJ are compared and analysed based on the existing experimental data of 105 long columns collected from previous literatures. It is found that EC4 and AIJ can provide accurate prediction for long columns with length-diameter (L/D) ratio less than 20, and EC4 is more stable. However, for slender columns when L/D ratio is greater than 20, the deviations of the calculated values of these three codes lose guidance. Furthermore, it is found that the deviation between the calculated and measured values of EC4 performs a power function with L/D ratio. Therefore, based on the calculation formula of EC4, a revised coefficient of L/D ratio is proposed, so that the revised formula can accurately predict the axial compressive capacity of slender columns without affecting the prediction of short columns.