N. BALASUBRAMANI AND R. THENMOZHI
Abstract
This paper comprises of the experimental study of eight column specimens. Out of which six are Double Skinned Hollow Concrete Filled steel Tubular (DSHCFT) columns annularly in-filled with Self compacting concrete (SCC) of M25 grade and steel tubes of yield strength 250Mpa and the remaining two are RCC (SCC) columns cast with the same SCC M25 grade of concrete and aspect ratio as that used for the DSHCFT specimens. Tests on the specimens were carried out under axial compressive load and with the experimental observations; various characteristics such as loaddeflection curve, stiffness, failure mode, confinement of concrete, ultimate compressive strength and ductility are discussed. For DSHCFT columns with a constant value of Diameter / thickness ratio of inner steel tube, slenderness ratio, grade of in-filled SCC and hollowness ratio, the effect of variation of outer steel tube thickness on the behavior of DSHCFT columns are reported. The experimental results are compared with the RCC (SCC) columns. Suitability of two different codes is verified. Within the scope of this investigation and its available results, some simplified equations for obtaining the ultimate strength of DSHCFT columns filled with self-compacting concrete for three various ratios of diameter of outer tubes and thickness of outer tubes (D o /t o ) of 57, 71 and 104 with constant diameter / thickness ratio of inner tubes (D i /t i ) of 25, slenderness ratio (ë SC ) of 16.7, grade of in-filled SCC of M25 and hollowness ratio (÷) of 0.36 are presented.