Seismic performance of core-steel tube with T-shaped steel reinforced concrete columns

Combining the advantages of the concrete-filled core-steel tube (CFCST) column and cross-shaped steel reinforced concrete (SRC) column, a novel core-steel tube with T-shaped steel reinforced concrete (CSTRC) column is proposed. The steel skeleton of CSTRC column consists of a core-steel tube and four T-shaped steels welded around the steel tube. Seismic performance of the seven composite columns are investigated by quasi-static tests, the effects of the cross-section form of core steel tubes, the steel flange width, and steel web height of composite column are also investigated. A finite element model is developed to conduct parametric studies to determine how the axial compression ratio, tube diameter-thickness ratio, concrete grade and steel ratio affects the bearing capacity and ductility of the composite column. The test results show that the T-shaped steel arranged outside the steel tube reduce the discrepancies in the mechanical properties of the concrete inside and outside the steel tube and play a positive role in restraining the concrete outside the steel tube. Compared with the contrast column, the CSTRC column exhibits good seismic performance, bearing capacity and ductility. With a ratio of flange width to section width of approximately 9/25, the outstanding ductility of CSTRC column is exhibited. The bearing capacity and the ductility of column decreases with the increase of axial compression ratio. The bearing capacity and ductility of the column improves with the increase of diameter-thickness ratio. The bearing capacity of column improves with the increase of concrete grade and steel ratio, while the ductility is decreased.