Behavior of multicell concrete-filled steel tube columns under eccentric loading

Multicell concrete-filled steel tube (MCFST) columns are used as vertical members in super high-rise buildings. However, the behavior of MCFST columns under eccentric loading has not been investigated in detail. Hence, seven MCFST column specimens were designed in this study. Experimental tests were performed on the specimens under an eccentric load and design recommendations were proposed. The main parameters investigated included the cross-sectional shape, number of cells, circular steel tube reinforced structure, structure of reinforcement cages, concrete strength, and the eccentricity ratio. The damage mode, bearing capacity, ductility, restoration capacity, and strain development were analyzed. The results showed that the circular steel tubes and reinforcement cage could significantly improve the mechanical behavior. Concrete with a higher strength significantly increased the bearing capacity but decreased the ductility. With an increase in the eccentricity ratio, the bearing capacity decreased, whereas the restoration capacity was reduced. Stress-strain relationships of plain concrete, single-cell concrete-filled steel tubes, and MCFSTs were considered in the fiber-based method to predict the deflection-load curves of the seven specimens. The results indicated that the curves calculated based on the stress-strain relationship of MCFSTs showed good agreement with the experimental results. (c) 2020 Elsevier Ltd. All rights reserved.