A new type of steel-concrete (SC) composite column was proposed. The proposed SC column is made by encasing square steel tube into circular concrete column confined by thin steel tube with diameter-to-thickness ratio of about 189. With width-to-thickness ratio of the encased square tubes, axial load ratio, and concrete-filling into encased tubes as main experimental variables, a total of thirteen specimens were made and tested under reversed cyclic loading to investigate the structural performance, ultimate strength, and defamation capacity of the proposed columns. Besides, an analytical method was presented to evaluate the cyclic response of the SC column.
