Abstract:

In this paper, the bearing mechanism of square concrete-filled steel tube （CFT） stub column under axial load is analyzed, and a constitutive relationship describing the equivalent single-axis compressive stress of the concrete core confined by square steel tube is put forward based on the typical constitutive model of confined concrete, which takes the restriction of steel tube to concrete as the effective lateral compressive stress. Then, according to the experimental results, several key parameters of the proposed constitutive relationship are analyzed and determined. The parameters include the coefficients of ultimate strain and effective lateral compressive stress, the transverse stress of steel tube and the strength. Moreover, the full-time load-strain curves of the square CFT stub column under axial load are obtained by using the proposed constitutive relationship, good accordance between the calculated results and the experimental ones being revealed. It is thus concluded that the proposed constitutive relationship is feasible in the evaluation of ultimate strength and deformation of square CFT stub columns.

Key words: square concrete-filled steel tube stub column, constitutive relationship, confined concrete, equivalent lateral compressive stress