DOI: 10.5176/2301-394X_ACE13.95
Authors: Albert Albareda-Valls, Jordi Maristany Carreras
Abstract:
Concrete-filled tubes are being increasingly used in architecture due to their improved ductility and strength under combined forces, especially under compression. However, in some specific situations, these sections may be not completely optimal from different points of view, such as in terms of fire protection or slenderness. The fact of locating the entire area of steel in the periphery of the section leads to have this material exposed to fire. Although the concrete filling plays a decisive role in absorbing part of the heat of the tube, these sections must be usually extra protected or reinforced for fire reasons. Besides, in case of slender columns, these sections are far from being optimized due to the filling of concrete in central areas of the core: the result is a high percentage of area which does not contribute to enhance the radius of gyration of the global section. In order to propose an alternative to concrete-filled tubes, this investigation analyzes the structural response of a derived typology known as concrete-encased tubes. This typology consists in surrounding steel tubes by a concrete layer which plays the basic role of protection. Apart from protection, this concrete can contribute actively to the axial response of the section directly or indirectly by confining the encased steel. Besides, the fact of being encased implies a clear restriction to buckling of the tube, and this fact allows using also thin-walled tubes for real designs. This investigation analyzes the compressive behavior of the encased steel tubes numerically in order to encourage designer to use these sections as a real alternative.
Keywords: Concrete-encased tubes; concrete-filled tubes; composite columns; confinement effect; local buckling
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