Uy, Tao and Han 2011

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Experimental Study and Results

This paper discusses axial compression tests performed on concrete filled steel tubes, as well as hollow steel sections. A combination of circular square, and rectangular columns were tested. The specimens were divided into four groups; group 1 wass composed of 72 short columns under axial loading, group 2 was 9 short columns, group 3 was 12 short beam-columns under axial compression and bending, and group 4 was 24 columns under axial loading. Group 2 investigates how a different loading method may affect the results, and group 4 investigates slender columns. Group 3 which was under combined loading, displayed very ductile characteristics, and both the strength and stability were significantly increased. For the short columns, short knife edges were placed on the end plates, and grooves were added to the plates to apply moments. For group 4, two hinges were added to both ends of the column to simulate pin-ended supports. Two strain gauges were added to both sides of each short column for a total of six gauges per column. Deflection for the short specimens was measured at mid height due to limited space. Longitudinal and transverse strains were measured using strain gauges with a length of 3mm. Both circular and square CFST columns displayed local outward folding failure, and thicker sections displayed local buckling at mid-span height. With the square hollow sections, local buckling occurred in convex and concave surfaces. The columns with larger D/t ratio displayed less ductile characteristics than a column with a smaller D/t ratio. The specimens using stainless steel over carbon steel displayed more ductile behavior and a greater residual strength. The specimens using high-strength concrete had a compressive strength of two times the normal strength of concrete.


References

Uy, B., Tao, Z., and Han, L. (2011) “Behaviour of Short and Slender Concrete-Filled Stainless Steel Tubular Columns.” Journal of Constructional Steel Research, 67(3), March, pp. 360–378. doi:10.1016/j.jcsr.2010.10.004