Experimental Research on Concrete Filled Thin-Walled Steel Tube Long Columns

Experimental research on square and octagonal concrete filled thin-walled steel tube long columns of 6 specimens in axial compression and 8 specimens in eccentric compression is undertaken. The relationship of global buckling bearing capacity of the columns and local buckling of the steel tubes is obtained. The test indicates that local buckling occurs in steel tube of each column before it reaches ultimate capacity, and has little effect on global buckling performance. The ultimate load decreases obviously with the increase of slender ratio and eccentricity. The ductility of columns increases with the increase of steel ratio in composite sections. Composite beam element of ANSYS is adopted in the finite element analysis. The theoretical results are agreed well with test..