Load-Carrying Capacity of CFST Columns: Current Design Rules Assessment

Concrete-filled-steel-tube (CFST) column, which consists of a hollow steel tube in-filled with concrete, has been widely adopted in the construction of infrastructures, tall buildings and bridges owing to its superior strength, stiffness and ductility contributed to the composite action. Currently, design equations have been proposed to predict the load-carrying capacity of CFST columns in design codes such as American Concrete Institute (ACI), American Institute of Steel Construction (AISC), Chinese Standard and Eurocode 4 (EC4), etc. However, as reported by some research studies, these codes could not predict the load-carrying capacity of CFST columns accurately, especially when the material strengths of other parameters exceeded their limitations specified in the codes. Besides, few studies have been carried out to compare the serviceability between different design codes with different parameters systematically. To fill up the above research gap, this study provides a comprehensive study to evaluate the applicability of the above current design codes. To start with, an experimental database consisting of 177 test results of CFST columns was assembled. Then the design equations stipulated in the current design codes were briefly introduced. Lastly, the load-carrying capacity obtained from the database was compared with the design strength. Results indicated that the design strengths predicted by ACI and AISC were the lowest since the confinement effect was not considered. Among all the above codes, EC4 made the most accurate prediction.