Integrity of industrial portal frames subjected to tying forces coming from fire or accidental actions

In most regulations, the surface of a compartment of an industrial building is limited to a certain area depending on the occupancy and provisions which are taken against the spread of fire. At the moment of collapse of a beam due to a fire or even due to another event, a tie force will be applied to the remaining structural portal frame. It can be rather easily stated that, in a 2D design with practical loads, a portal frame construction of concrete with clamped columns at the base and a hinged beam will never obtain a sufficient bearing capacity to withstand loads stated in the recommendations in case of a fire or those stated in EN 1991-1-7 for an accidental action. To tackle the issue of a possible progressive collapse, the roof can be provided with a wind bracing, a diaphragm made from metal sheet decking, or other provisions. Another possible solution could be the utilisations of edge profiles, which must be sufficiently rigid to incorporate adjacent portal frames in the reaction mechanism. An analytical approach is derived, which is checked by thermo-plastic analysis using the finite element software tool SAFIR® from Liège University. The findings have been illustrated using various calculated examples. Keywords: industrial portal frame, fire, accidental and unforeseen actionstatus: accepte