Behaviour and strength of CFDST circular short columns
Volume Title: ICASGE2025
Paper ID : 1111-ICASGE-FULL (R1)
Authors
Abstract
This paper presents the results of tests on six Concrete-Filled Double Skin Tubular (CFDST) short columns and one traditional Reinforced Concrete (RC) column. The CFDST columns featured inner and outer circular steel skins centrally aligned and filled with concrete in between, with all columns having a height of 1250 mm and an outer diameter of 300 mm. Welded strips connected the inner and outer skins at both ends. The RC column featured a 300 mm diameter, a 1.0% steel reinforcement ratio, and the same height 1250 mm. The study explored the effects of key parameters, including the ratio of inner to outer diameters (Di/Do), the ratio of outer diameter to steel skin thickness (Do/ts), and the ratio of steel skin area to wall area. Inner and outer steel skins were tested with three thicknesses, 1.5 mm, 2.0 mm and 2.5 mm, and two inner diameters, 170 mm and 220 mm were evaluated. Measurements included column shortening, steel strains, and failure modes. The results showed that failure occurred due to local buckling of the steel skins. The column strength was highly sensitive to the Di/Do ratio, while the Do/ts ratio significantly influenced behavior, ductility, and strength. The RC column’s strength was similar to that of the CFDST column with 2.0 mm skin thickness and a 170 mm inner diameter, but the CFDST columns exhibited much higher ductility. The findings were compared with strength prediction equations proposed by various researchers, providing a detailed evaluation of their accuracy for CFDST short columns.
Keywords
Subjects