Inspection of recent fire events in large compartments reveals them to have a great deal of non-uniformity, they generally burn locally and move across floor plates over a period of time. This phenomenon which generates transient heating of the structure is idealized as “travelling fire”.A first series of tests was launched to define a fire load representative of an office building according to Eurocodes. Additional tests where the fire dynamics were controlled were launched to develop an understanding of the fire exposure to steel structures.Then, a second series of large scale tests were performed in real building dimensions. These tests had no artificial control over the dynamics, which allowed a realistic characterization of the fire. The fire load was identical for all tests, only the openings were modified.CFD numerical models were developed to reproduce the experimental campaign and to launch parametrical analyses. This allowed to provide information concerning the conditions which may lead (or not) to a travelling fire scenario.An analytical model for the characterization of a travelling fire was developed and implemented in a simple calculation tool. It allows to evaluate the fire location, the gas temperatures in the flames, the heat fluxes in the different parts of the compartment and the temperature in a steel member. In addition, the methodology is introduced in the FEM software SAFIR and OpenSees.Ultimately, a design guide was prepared including worked examples which are detailed step-by-step and for which the influence of the inputs on the results is analysed.