Thermo-Structural Analysis of an Open Section Cold-Formed Steel Beam in Contact with a Concrete Slab and a Masonry Wall in Fire Situation

Abstract

This work presents the results of numerical analyses, both thermal and structural, of a pinned-pinned open cross section of a "U-shaped" cold-formed steel beam in a fire situation. The beam was in physical contact with a concrete slab and a masonry wall. The eventual partial compartmentalisation due to the wall was disregarded. The field of temperatures for the steel-concrete-wall elements was determined using the software programs Super Tempcalc and Ansys. For structural analysis the software Ansys was used. Restrictions due to the lateral displacement, the compatibility of transversal displacements at the points of contact between the slab and the beam, local buckling and restrictions to the thermal strains at the end supports were taken into account. Material and geometrical nonlinearities were considered, as well as the variation of the stressstrain diagrams with temperature, according to Eurocode prescriptions. The variation of the resistance reducer with the time of fire exposure was also evaluated. Based on the adopted model, the structure under standard fire exposure is not adequately safe. More research is under development to consider compartmentalisation and natural fire.