Behavior of axially loaded circular stainless steel tube confined concrete stub columns

Stainless steel tube confined concrete (SSTCC) stub column is a new form of steel-concrete composite column in which the stainless steel tube is used to confine the core concrete without resistance to the axial load directly. It could take the advantages of both the stainless steel tube and the steel tube confined concrete columns. This paper presents the experimental investigation of circular SSTCC stub columns subjected to axial load. Meanwhile, comparative tests of the circular concrete-filled stainless steel tubes and circular hollow stainless steel tubes were also conducted. The experimental phenomena of specimens are introduced in detail and the experimental results are analyzed. Through the investigation of axial stress and hoop stress on the stainless steel tube, the interaction between stainless steel tube and core concrete is studied. The experimental results showed that the stainless steel tube provides confinement to the core concrete, increasing the compressive capacity of core concrete significantly. In addition, the confinement of stainless steel tube in SSTCC stub columns is larger than that in concrete-filled stainless steel tubes. Therefore, the load-carrying capacity of SSTCC columns is higher than that of concrete-filled stainless steel tubes. Besides, an equation was proposed to calculate the load-carrying capacities of SSTCC columns and concrete-filled stainless steel tube columns. The calculated results agree well with the experimental results.