A generalised steel/reinforced concrete beam-column element model for fire conditions

A generalised beam-column element is presented for three-dimensional composite structures at ambient and high temperatures. The element can model reinforced concrete and steel sections of different shapes. The element has been implemented in the software VULCAN, and has then been validated by comparing with existing theoretical and experimental results. The formulation currently includes both geometrical and material non-linearities and considers unloading for steel, cracking and crushing for concrete, and thermal expansion and degradation of material for both with elevated temperatures. The cross-section is divided into an appropriate number of segments so that non-uniform temperature profiles, variations of constitutive relationships and thermal strains across the section can be represented accurately.