EVALUATION FORMULA FOR CALCULATING YIELD STRENGTH OF SQUARE CFT COLUMNS

Abstract

The purpose of this study is to propose a method to evaluate yield strength of square CFT columns. Yield strength of a CFT column is calculated by assuming the stress-strain relationships of concrete and steel tube and using the Navier's hypothesis. Yield strength is compared with the superposed strength of square CFT short columns. Yield strength can be classified by four types of m-n interaction curves depending on the strain condition of the section. The formula for calculating yield strength is proposed by straight lines for each type. We show the difference between the simplified strength and yield strength and the method for determining the type and a calculation example.