Large scale fire test: travelling fire with flashover under ventilation conditions and its influence on the surrounding steel structure

In the frame of the European RFCS-TRAFIR project, different natural fire tests in large compartment were conducted by Ulster University, involving steel structure and aiming at understanding the conditions in which a travelling fire develops, how it behaves and impacts the surrounding structure. During the experimental programme, the path and geometry of the travelling fire was studied and temperatures, heat fluxes and spread rates were measured. This paper presents the selected experimental data from the third fire test in terms of gas temperatures recorded in the test compartment at different positions and levels. The paper also presents the influence of the traveling fire with flashover on the surrounding structure via temperatures recorded in the selected steel columns and beams. The temperatures in the test compartment were found to be dependent on the positioning of the travelling fire as well as on the height from the floor level. It was found that the non-uniform temperatures in the compartment lead to transient heating of the nearby structural steel elements which is different from a standard furnace test. These non-uniform elevated temperatures result in a reduction of the fire resistance of the structural elements which may influence the global stability of the structure. The results obtained during the test and lessons learnt will help to understand the behaviour of the travelling fires and their influence on the structural members. This knowledge will help to reduce the travelling fire associated risks in future.