A Simple Formula for Predicting the Compressive Strength of Circular CFT Stub Columns

Abstract

In this paper, the predictions of ultimate strength of circular concrete-filled steel tube (CFT) stub columns using current design codes such as AIJ-2001, AISC-2005, DL/T-1999, and Eurocode 4-2004, are examined and compared with published experimental tests of CFT short columns made with normal- and high-strength steel and concrete. Based on the investigations, a simple formula for predicting the ultimate strength of CFT stub columns is proposed. The concrete confinement, which depends mainly on the ratio of the external diameter of the steel tube to the plate thickness, the yield stress of the steel tube, and the unconfined compressive strength of the filled concrete, was reasonably achieved in the proposed formula. From comparisons with the published experimental data for CFT short columns of normal and high strength steel and concrete, the present formula is shown to give a good representation of the ultimate strength of circular CFT columns.