Experimental behaviour of partially loaded concrete filled double-skin steel tube (CFDST) sections

The experimental behaviour of concrete filled double-skin steel tube (CFDST) sections subjected to partial compression is reported in this paper. Fourteen specimens with outer and inner steel tubes of circular hollow section (CHS) and fifteen specimens with outer and inner steel tubes of square hollow section (SHS) were tested. The test parameters included: 1) hollow ratio, 2) top endplate thickness, and 3) partial compression area ratio. The test results indicated that the CFDST columns under partial compression behaved in a ductile manner. The partial compressive behaviour and the failure modes of partially loaded CFDST stub columns were significantly affected by the parameters investigated. Finally, a simplified model for predicting the bearing capacity of partially loaded CFDST sections is proposed.

► CFDST column subjected to axially partial compression.
► Behaviour of partially loaded CFDST column under different parameters.
► Calculation for the bearing capacity of partially loaded CFDST sections.