Eccentric compressive behavior of square concrete-filled stainless steel tube (CFSST) stub columns

Abstract

To study the eccentric compressive behavior and mechanism of square concrete-filled stainless steel tube (CFSST) stub columns, a total of 12 specimens with different steel ratio and load eccentricity under eccentric load was investigated. The results demonstrated that the failure modes of all square CFSST stub columns were the outward local buckling of the stainless steel tube at the compression side and two adjacent sides. The load-longitudinal deformation curve of specimens exhibited three stages, including elastic stage, elastic-plastic stage, and descending stage. The longitudinal strain distribution in the cross section at the mid-height of the specimens generally satisfied the plane-section assumption during the loading process. Increasing the steel ratio of specimens significantly improved the ultimate bearing capacity. Meanwhile, the ultimate bearing capacity of the specimens decreased with the load eccentricity, and the second-order effect became more pronounced with the increase in eccentricity. Finally, based on the existing specification, this study proposed a prediction formula for the eccentric bearing capacity of square CFSST stub columns by modifying the eccentric reduction coefficient accompanied by adopting the method of equivalent cross section. The formula was verified using an established database of eccentric compression CFST stub columns in the existing literatures.