Concrete filled steel tube structures have gained booming development in recent decades, especially in China. Simplified methods have been proposed in design codes, such as the Eurocode 4 (EC4) and the China engineering and construction specification (CECS). In EC4, the confinement effect is reasonably related to slenderness and load eccentricity. The CECS method is much straight forward in that the slenderness ratio and load eccentricity are treated as independent reduction factors. To make use of the advantages of both the CECS and the EC4 methods, the CECS method is modified to consider the confinement effect associated with slenderness and load eccentricity. It is shown that the proposed method can predict well the ultimate load capacity of circular section concrete filled steel tube columns.
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 J. Y. R. Liew and D. X. Xiong, “Effect of Preload on the Axial Capacity of Concrete-Filled Composite Columns,” Journal of Constructional Steel Research, Vol. 65, No. 3, 2009, pp. 709-722.
 B. C. Chen, Z. J. Ou, L. Y. Wang and L. H. Han, “Experimental Study on Carrying Capacity of Concrete Filled Steel Tubular Column under Eccentrically Load,” Journal of Fuzhou University-Natural Science Edition, Vol. 30, No. 6, 2002, pp. 838-844.