Research on the Axial Compressive Behavior of Concrete-Filled Steel Tubular Column Reinforced with Annular Stiffener

This paper presents experimental and theoretical studies on the axial compressive behavior of an innovative type of concrete-filled steel tubular (CFST) composite column reinforced with annular stiffener. The annular stiffener is constructed by curved steel plate and circumferential plate is acting as the interface connector. It is expected to improve the axial compressive performance of conventional columns through the double confined effect of outer steel tube and inner annular stiffener on the core concrete. In order to study the axial compressive behavior of the steel-reinforced concrete-filled steel tubular (SRCFST) column and the influence of related design parameters inclusive of the presence of annular stiffener, space of circumferential plate, slenderness ratio on the axial compressive performance, experimental study was carried out on two CFST columns and six SRCFST columns. The failure mode, load–displacement response and load-strain curves were comprehensively analyzed. The results show that the innovative SRCFST columns have higher load-carrying capacity, stiffness compared with the conventional columns. The internal annular stiffener could effictively participate in the overall loading process and improve the failure mode of the specimen. Theoretical model of the confined mechanism for the coloumn is developed and the calculation formula was proposed to provide a reference basis for the application of this type of composite coloumn in practice.