ABSTRACT
Composite action between different structural materials has been utilized in bridge and building construction for a number of years. Traditionally, constructed of steel and concrete, composite structures take advantage of the strength characteristics of each material. For example, a composite bridge girder utilizes the properties of steel in the tension zone and the compressive strength of the concrete in the deck. Similarly, a column made of a steel tube filled with concrete maximizes the steel strength by restraining the primary fialure mode, i.e., local buckling of the tube wall, while simultaneously improving the load sharing between steel and concrete. The tube also provides confinement for the concrete, preventing early spalling and effectively raising the available strength of the material. Two materials are thus mutually beneficial (Bridge & Roderik 1977, Galambos & Ravindra 1978, Gardner & Jacobson 1967, Janss 1974, Johnson & May 1978, Kim & Lee 2005, Kloppel & Goder 1957, Knowles & Park 1969, Loke 1968, Morino 2001, Ravindra & Galambos 1978, Salani & Sims 1964, Wang et al . 2004, Zong et al. 2002).
