The purpose of this research is to clarify the effect of cross sectional size and shape on the uni-axial compressive behavior of concrete filled square steel tube (CFT) short columns. Compression tests of square CFT short columns with cross sectional size 400mm have been conducted. This paper first presents the test results concerning compressive strength, and discusses the evaluation of the strength of square CFT short columns considering the effects of cross sectional size and shape. As a result, following have been found. i) effects of cross sectional size and shape on the square CFT short columns were clearly observed, ii) the compressive strength of various size square CFT short columns can be predicted by proposed numerical formula.
