Fire resistance of a steel pitched roof portal frame

摘要

The behaviour of plane one storey two columned steel frames with pitched roof which are exposed to fire are examined. In a pitched roof portal frame if the beams are flexible and the roof is shallow (i.e. is without a great inclination) it is possible for the phenomenon of snap through to present itself. The circumstances under which the phenomenon known as snap-through in such frames occurs have been investigated. Recently regarding the relative problem of the large displacements of plane frames, a simple formulation was proposed which was based on position description and was used in the present work. If the phenomenon snap-through does not occur early in a portal frame with a pitched roof, the frame can finally fail with the formation of a plastic collapse mechanism. For a more exact analysis of a frame the finite element method can be used. The non linearity of material with the non linearity of an axial stress strain bar laws and the geometrical nonlinearities can be described.