Modelling of plastic strength of composite tubular members under elevated temperature conditions

摘要

The use of composite member made of steel tube filled with concrete is prevalent in building construction due to its favourable construction efficiency and fire resistance characteristics. When using such members, it is necessary to determine their elastic stiffness, plastic strength and their corresponding characteristics under fire conditions for design purposes. The determination of such data becomes more complicated when non-uniform temperature distribution in the cross-section exists. It is also difficult, if not impossible, to obtain those data for every structural element through fire tests because of economic constraints. Therefore, calculation procedure to obtain numerical solution is an attractive alternative in terms of economy as well as efficiency. This paper details the calculations of the elastic stiffness and plastic bending strength of a concrete-filled steel tubular member under a fire scenario. Temperature distribution of the cross-section of the member is calculated on the basis of heat transfer software and the resulting properties are compared for cross-sections modelled with and without thermal contact resistance elements at the steel-concrete interface.