Hysteretic behavior comparison of austenitic and lean duplex stainless steel square hollow section members under cyclic axial loading

Abstract

In this study, cyclic loading tests for a total of 10 specimens were performed in order to study the cyclic response of square hollow section bracing members with three types of cold-formed stainless steel materials; two austenitic stainless steels and one lean duplex stainless steel. The buckling behaviors, tensile strength, and energy dissipation capacity of the specimens were investigated according to the difference of material properties, width-thickness ratio and slenderness ratio. This study indicated that the number of cycles for grade 304 stainless steel tubular specimens at ultimate state was lower than that of grade 316 stainless steel specimens due to tensile fracture in the weld heat-affected zone. The ultimate strength and energy dissipation capacity of the lean duplex stainless steel specimens was also lower than those of austenitic stainless steel specimens due to initial local buckling. It is found that the grade 316 specimens showed the higher energy dissipation capacity and energy index by 1.78, 2.72 times on average, respectively, compared to the grade 304 members despite their higher material strength. This study also showed that European code tended to underestimate the compressive buckling strength of the bracing members, while Specification for the Design of Cold-formed Stainless Steel Structural Members by American Society of Civil Engineers provided unconservative the buckling strength prediction in the long columns and duplex stainless steel members.