Structural Fire Performance of Concrete-Filled Steel Hollow Structural Sections: State-of-the-Art and Knowledge Gaps

Concrete filled steel hollow structural (CFS) sections are an efficient, cost-effective, and architecturally attractive means by which to support large compressive loads in buildings, and they are thus increasingly popular among structural engineers and architects. Consisting of hollow steel tubes that are filled with one of a variety of types of concrete filling, CFS columns provide enhanced structural fire resistance and can, in many circumstances, be used with little or no applied fire protection insulation. The structural performance of modern CFS members, which may incorporate unreinforced or steel fibre reinforced high strength concrete infill, under the realistic thermal and loading scenarios that would be expected for a structural frame in a real building fire, is not fully known. This can lead to difficulties in design and construction which may discourage application of CFS members. This paper reviews current knowledge of the fire performance of CFS columns. A summary of fire scenarios, materials of construction, mechanical loading conditions, and fire protection systems considered in the available research (whether experimental or numerical) is provided, along with a discussion of gaps in knowledge and the possible consequences of these gaps for rational, performance-based design and analysis of structures incorporating CFS columns.