Based on the mega-columns in the projects of China Zun and Tianjin 117 Tower

4 multi-cell concrete-filled steel tube mega-column specimens were designed

and experimental study was conducted under one-way repeated eccentric compression load. The specimens include one 1/13 scaled octagonal 13-cell model of China Zun

one 1/13 scaled octagonal 13-cell model of China Zun with circular steel tube at corners

and two 1/12 scaled hexagonal 6-cell models of Tianjin 117 Tower. The damage evolution

bearing capacity

deformation restoration capacity

stiffness

and degeneration of the specimens with different section shapes and constructions were theoretically analyzed. Results show that all the specimens had good behaviors under eccentric compression. The setting of octagonal 13-cell mega-column with circular steel tube at corners could effectively reduce the damage evolution and significantly improve the bearing capacity and deformation capacity. Higher bearing capacity could be obtained when the eccentricity of the hexagonal 6-cell mega-column specimen was small

and the restoration capacity of the specimen was relatively good when the eccentricity was large. Various codes and the fiber based method were used to estimate the N-M interaction curves and F-Δ curves of the specimens

and the calculation results were more conservative compared with experimental results. Hence

referring to the features of multi-cell concrete-filled steel tube columns

a modified simplified calculation method for compressive strength of multi-cell concrete-filled steel tube (fsc) was proposed on the basis of the calculation method in code GB 50936 and the constitutive relation of concrete proposed by Han. The calculated N-M interaction curves and bearing capacity were in good agreement with measured results

which suggests that the simplified method can be used as a reference for the calculation of multi-cell concrete-filled steel tube columns under eccentric compression.