An alternative design approach, helpful in the critical temperature evaluation for a gable steel frame exposed to fire, is proposed and discussed in this article. This approach is based on the specification of a system of equilibrium formulae, generalized to the case of fire. All these equations result from the graphical identification of the redundant bending moment distribution in the frame members relating to the particular collapse mechanisms being kinematically admissible. Only such a mechanism which corresponds to the activation of a suitable sequence of the appropriate number of plastic hinges while maintaining the requirements of the classical bending moment redistribution is recognized as conclusive for the considered frame structure
