This thesis has developed an analytical model for the prediction of the critical temperature of cellular beam made based rolled in fire situation. These results will be based on the development of a new analytical model of isostatic cellular beam subjected to fire. To ensure the reliability of the developed model, the following steps were considered: The realization of large-scale tests in the laboratory, the development of a finite element model in the SAFIR software; Validation of finite element model in comparison tests laboratory, development of simplified analytical model, validation of the analytical method by a parametric study using the finite element model. The finite element model and the analytical model is able to reproduce with a satisfactory level of precision the complex behavior of cellular beams in case of fire
