To investigate the influence of reinforcement cages and circular steel tube on special-shaped multi-cell concrete-filled steel tube (SMCFST) under reciprocating axial load

three large-size specimens were designed based on Z15 tower. The failure model

load-deformation curves

skeleton curves

bearing capacity

deformation capacity

stiffness degeneration

cumulative energy dissipation

and strain of the specimens were analyzed. Codes of different nations were utilized to calculate the bearing capacity of the specimens. The results shown that the reinforcement cages could enhance the initial stiffness and bearing capacity of the specimens. The circular steel tube could further improve the initial stiffness and bearing capacity

as well as significantly enhance the ductility

cumulative energy dissipation

and the behavior of the specimens at the later stage. Moreover

since the codes ignored the effect of horizontal diaphragms and the different buckling mechanisms between inner steel plate and outer steel plate

the calculation results were significantly lower than the experimental results. Therefore

it was necessary to further investigate the calculation method of the multi-cell concrete-filled steel tube. The circular steel tube was suggested to be used in buildings to improve the axial compression behavior of the special-shaped multi-cell concrete-filled steel tube.