ABSTRACT
A series of tests were conducted by Zhao and Grzebieta (2002), Zhao et al. (2002a, 2002b, 2010a), Elchalakani, et al. (2002) on CFDST stub columns with the four combinations shown in Figure 1. Closed form solutions were derived for CFDST section capacity in compression. Design formulae for CFDST beam-columns were presented in Han et al. (2004), Tao et al. (2004). Experimental investigation was carried out on CFDST subject to pure bending by Zhao and Grzebieta (2002), Tao and Han (2006) for RHS + RHS, Han et al. (2004) for RHS + CHS, Lin and Tsai (2001) for
1 INTRODUCTION
Concrete-Filled Double Skin Tube (CFDST) consists of an outer tube and an inner tube, with concrete infill between them (Zhao and Han 2006). There may be a potential for concrete filled double skin tubes to be used as columns in building structures, bridge piers and composite piles in offshore applications. There are four combinations of Rectangular Hollow Section (RHS) and Circular Hollow Section (CHS) as outer and inner tubes, as shown in Figure 1.
