Civil Engineering, Ferdowsi University of Mashhad
This paper deals with simple portal or gable steel frames with varying moment of inertia. Critical load for such frames is calculated by means of a very simple and approximate method through which the variation of moment of inertia for the members is considered by a quadratic function and then the equilibrium and continuity conditions have been used. The degree of precision of this method has been checked by a computer method in a numerical example. The method is applicable only for one bay steel frames.