Propagation tests with uniformly distributed cellulosic fire load

In the recent past, the necessity to have a better understanding of fire dynamics and of the full structural response under real fires was the motivation for several large-scale non-standard fire tests. Nowadays, the novel need to better comprehend the fire dynamics behind the so called “travelling fires” underlined the limitations of those non-standard fire tests. The lack of standardised procedures does not allow making effective comparisons and drawing scientific conclusion from these tests. The fire group of Liege University performed eleven non-standard or “natural fire” tests within the context of the RFCS research project TRAFIR sponsored by the E.U. Commission (grant N°754,198). The aim of this experimental campaign was to determine a uniformly distributed fuel arrangement that would lead to a medium fire growth as recommended for office buildings in Eurocode 1. This paper presents the test results in terms of fire growth rate, flame length, temperature along the flame centreline, fluxes at a distance from the fire and temperatures on wood sticks. The outcomes define a uniformly distributed fuel load arrangement leading to a desired fire development and also provide valuable experimental information on the fire dynamics related to fire spread. In conclusion, a well-established methodology to perform natural fire tests has been defined, from the ignition system up to the exact fuel arrangement. This methodology could be used in the future for natural fire tests in order to allow a comparison of different conditions (ventilations, geometry, nature of the boundaries, etc.) while considering the same fire load distribution to understand, for example, the conditions in which a travelling fire can develop or not. The experimental results reported here can also be used to validate or calibrate various existing or future sub-models developed by other authors.