Fire Experiment Inside a Very Large and Open-Plan Compartment: x-ONE

Abstract

The traditional design fires commonly considered in structural fire engineering, like the standard fire and Eurocode parametric fires, were developed several decades ago based on experimental compartments smaller than 100 m2 in floor area. These experiments led to the inherent assumption of flashover in design fires and that the temperatures and burning conditions are uniform in the whole of the compartment, regardless of its size. However, modern office buildings often have much larger open-plan floor areas (e.g. the Shard in London has a floor area of 1600 m2) where non-uniform fire conditions are likely to occur. This paper presents observations from a large-scale fire experiment x-ONE conducted inside a concrete farm building in Poland. The objective of x-ONE was to capture experimentally a natural fire inside a large and open plan compartment. With an open-plan floor area of 380 m2, x-ONE is the largest compartment fire experiment carried out to date. The fire was ignited at one end of the compartment and allowed to spread across a continuous wood crib (fuel load ~ 370 MJ/m2). A travelling fire with clear leading and trailing edges was observed spreading along 29 m of the compartment length. The flame spread rate was not constant but accelerated with time from 3 mm/s to 167 mm/s resulting in a gradually changing fire size. The fire travelled across the compartment and burned out at the far end 25 min after ignition. Flashover was not observed. The thermocouples and cameras installed along the fire path show clear near-field and far-field regions, indicating highly non-uniform spatial temperatures and burning within the compartment. The fire dynamics observed during this experiment are completely different to the fire dynamics reported in small scale compartments in previous literature and to the assumptions made in traditional design fires for structural design. This highlights the need for further research and experiments in large compartments to understand the fire dynamics and continue improving the safe design of modern buildings.

Fire dynamics inside a large and open‐plan compartment with exposed timber ceiling and columns: CodeRed #01

“…A new facility was built at CERIB's site in Epernon, France that enables variation in both fuel load, ventilation and ceiling construction; parameters which are planned to be varied in future experiments. The parameters build on a series of experimental campaigns in 2017 and 2019, known as x‐ONE 11 and x‐TWO , 17 that were conducted in a non‐combustible structure in Poland with a floor area of ~380 m 2 to study travelling fire dynamics in open‐plan compartments. These experiments are currently the largest compartment fire experiments to date in terms open‐plan floor area 11,17 .…”

“…No experimental evidence currently exists to investigate the fire dynamics experienced in large compartments (> 100 m 2 ) with exposed timber and how these differ from small compartments and non-combustible large compartments. Richter et al [16] has assessed the thermal response (charring rate and zero strength layer) of timber slabs under a range of design fires (travelling fires, Eurocode parametric fires, and the standard fire). The authors adopted design fire models used typically for non-combustible compartments and, similarly to Rackauskaite et al [10], highlighted the lack of validated design fire tools for open-plan compartments with exposed timber.…”

“…The authors called for further research to be undertaken to confirm whether findings from smaller compartments (<100 m 2 in floor area) apply to large compartments with exposed timber too. Existing compartment fire experiments and modern design aspirations are shown in Figure 1 11 …”

“…The compartment is based on a non‐combustible building previously used for travelling fire experiments and therefore allows for a future comparison of fire dynamics in combustible and non‐combustible compartments 11 , a detailed comparison is outside the scope of this paper.…”

Impact of Mass Timber Compartment Fires on Façade Fire Exposure

“…The compartment had a fully exposed CLT ceiling and GLT columns. Previously, the research team had already carried out two comparable tests in non-combustible compartments [27,28]. In a first comparison, the research team concluded that the CLT ceiling impacts the total HRR substantially, nearly doubling the peak HRR from 69 MW [27] and 58 MW [28] to 121 MW [26].…”