Compartment Fire Tests Research Articles

The critical discontinuity of vertical temperature distribution along window opening height from intermediate-scale compartment fire

The fire plume spilled from a window is believed to be one of the main fire sources with respect to a building façade fire, which happened previously in China. To have a deep understanding of vertical temperature distribution at window opening is of significance. In the current contribution, a series of compartment fire tests under over-ventilation were conducted with a 1.35 m × 1.35 m × 1.35 m compartment to clarify the critical discontinuity position (HD) by varying window opening sizes, opening aspect and heat release rate (HRR). Temperature history at the window openings were recorded by a thermocouple net. A theoretical calculation method of HD is detailed according to the compartment configuration. It is found that the critical discontinuity area is observed apparently along the window opening height, which has a big temperature difference. By the comparison of experimental and theoretical results, the constant comprehensive coefficient of 1.68, 1.92 and 3.85 of 300 kW, 600 kW and 900 kW are got for an engineered empirical prediction model are proposed, respectively. It provides an insight for the understanding of critical temperature discontinuity and reference for engineering calculations.

TIMpuls - Large-scale timber compartment fire tests

TIMpuls - Large-scale timber compartment fire tests

Introducing an active opening strategy to mitigate large open-plan compartment fire development

‘Travelling fire’ behaviour was found in large compartment fire tests with initial window openings, which exhibits slow fire development benefiting fire safety design and firefighting. Since much faster fire spread is found in the same compartment with glass panels, this paper attempts to explore an ‘active opening’ strategy to open the glass panels to regain the ventilation assumptions. The proposed strategy uses an activation temperature to control the opening and it has been now implemented in the CFD fire models. Two extreme situations, i.e., initial opening without glass and windows initially closed with glass, are investigated. A striking difference of fire behaviour is found as flashover is observed in the latter scenario compared to the localized burning in the former case. While implementing active opening, the influences of activation temperature and window height on the performance of mitigating fire development are investigated. It is found that a lower activation temperature allows faster removal of hot smoke and thus avoids spontaneous ignition. Furthermore, the effect of window height is demonstrated as higher opening reduces the thickness of hot smoke, which effectively enables lower floor radiation and thus mitigates fast fire spread.

Experiment study of fire characteristics in full-scale bedrooms under different vents and sprinkler conditions

The risk of fire in residential buildings is relatively high, with a significant number of incidents and loss of life reported. This study aimed to examine fire scenarios in bedroom by conducting real scale experiments with different set-up of vents and using realistic fuel loads. Five full-scale compartment fire tests were conducted, and a sprinkler system was installed in one of the rooms. The experimental setup, fuel arrangement, and instrumentation are described, and the fire characteristics was analyzed based on visual observations and temperature data processing. The performance of the fire detectors and sprinklers in the tests are discussed. The influence of opening size on the peak temperature, heat release rate, and the constant coefficient of Kawagoe law are estimated and analyzed. Furthermore, a non-dimensional neutral plane height was found to have strong relationship with the constant coefficient of Kawagoe law.

Application of travelling behaviour models for thermal responses in large compartment fires

Large open-plan compartment fires in modern buildings may exhibit a local burning region travelling across the floor plan as a ‘travelling fire’. This phenomenon has been found in the forensic investigations of fire accidents and in the large compartment fire tests. The fire impact in a large compartment is spatially non-uniform and time-variant, which can cause severe local damage to structural components. Advanced from the previous models assuming constant travelling, the natural fire model established in this paper comprises time-variant and test-based travelling behaviour models and localised fire models of various modes. It is demonstrated with the fast-spread Veselí fire test and the slow-spread Malveira fire test. A generic structural model is set up within OpenSees for fire to examine the thermal impact on structural members under various travelling fire scenarios of different travelling parameters, fire travelling directions, and beam sizes. Locally much higher thermal responses are represented after introducing behaviour models while adopting the same design fire load. Based on the work in this paper, a library of design fire models can be potentially enabled to examine the fire safety performance of structures regarding the realistic fire load and fire impact aiming for discovering unknown worse fire scenarios.

Travelling fire in full scale experimental building subjected to open ventilation conditions

PurposeIn the frame of the European RFCS TRAFIR project, three large compartment fire tests involving steel structure were conducted by Ulster University, aiming at understanding in which conditions a travelling fire develops, as well as how it behaves and impacts the surrounding structure.Design/methodology/approachDuring the experimental programme, the path and geometry of the travelling fire was studied and temperatures, heat fluxes and spread rates were measured. Influence of the travelling fire on the structural elements was also monitored during the travelling fire tests.FindingsThis paper provides details related to the influence of travelling fires on a central structural steel column.Originality/valueThe experimental data are presented in terms of the gas temperatures recorded in the test compartment near the column, as well as the temperatures recorded in the steel column at different levels. Because of the large data, only fire test one results are discussed in this paper.

A building information modeling‐fire dynamics simulation integrated framework for the simulation of passive fire protection in a mid‐scale cross‐laminated timber compartment: Numerical implementation and benchmarking

AbstractConstruction fires are a big threat to worker safety and property safety. Mass timber buildings under construction are largely unprotected as they are not yet equipped with active fire protection systems. With the addition of Types IVA, B, and C, the 2021 International Building Code adopted stricter requirements for mass timber buildings that are under construction. Cross‐laminated timber (CLT) is used as the primary structural element for high‐rise mass timber buildings. However, to date, limited number of research studies investigated the impact of passive fire protection for CLT buildings that are under construction. To facilitate a better understanding of construction fires and their consequences, it is necessary to develop a numerical modeling solution for the early phases of a CLT construction project, which can be achieved by using building information models together with fire dynamics simulation (FDS). However, the numerical modeling technique must be benchmarked against experimental data first to then extrapolate the modeling technique to explore other parameters and conduct FDS analysis. Therefore, this paper develops and benchmarks a numerical modeling solution against a mid‐scale CLT compartment fire test by applying the FDS tool to simulate the fire behavior within the CLT compartment. The FDS analysis results are expected to validate the practicality of simulating the fire behavior in CLT structures using the numerical model proposed in this study. The overarching goal of this study is therefore to develop a comprehensive numerical modeling solution to simulate and assess passive fire protection sequencing in CLT buildings that are under construction.

Experimental and Numerical Investigations on Steel Columns Compartment Subjected to Travelling Fires

AbstractIn the frame of the European RFCS TRAFIR project, three large compartment fire tests involving steel structure were conducted by Ulster University, aiming at understanding in which conditions a travelling fire develops, as well as 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. Influence of the travelling fire on the structural elements was also monitored during the travelling fire tests. This paper provides details related to the influence of travelling fires on structural steel columns. The experimental data is presented in terms of the gas temperatures recorded in the test compartment near the column, as well as the temperatures recorded in the steel column at different levels. The scope of the experimental work is extended using CFD simulations with FDS software, which demonstrate with good agreement with measurements in the steel column exposed to travelling fires.

A Small-Scale Test to Examine Heat Delamination in Cross Laminated Timber (CLT)

This paper examines the strength of wood adhesive bonds at high temperatures. The goal of this research is to better understand the conditions of heat delamination in cross laminated timber (CLT) that is exposed to fire. Heat delamination in CLT occurs when one lamination detaches from the composite panel before the char front reaches the bondline. Timber that falls from the panel, as a result of delamination, contributes additional fuel to the fire, which can cause fire regrowth, while the loss of a lamination causes a sudden loss in strength. Currently, to demonstrate that an adhesive does not delaminate, it must pass a full scale (6 m by 3 m) compartment fire test as prescribed in the PRG-320 product standard. In this work, we scaled down the mechanical loads and temperatures to 300 mm lap shear specimens. Seven different adhesives were tested and compared against solid wood controls with the same geometry as the lap shear specimens. Quasi-static tests were run where the specimens were loaded to failure at 25 °C and 260 °C, when the samples were at thermal equilibrium. Additionally, creep tests were performed where the load and temperature ramp was matched to the adhesive bondline temperatures measured in the large scale PRG-320 tests. With the exception of some of the polyurethane formulations, all adhesives passed the scaled-down creep test that resembles the PRG-320 standard. Of the polyurethane adhesives tested, only one formulation remained intact for the duration of the test. These results can be used to help better predict which adhesives may pass the PRG-320 test prior to full scale testing.

Modelling the Effects of Boundary Walls on the Fire Dynamics of Informal Settlement Dwellings

Characterising the risk of the fire spread in informal settlements relies on the ability to understand compartment fires with boundary conditions that are significantly different to normal residential compartments. Informal settlement dwellings frequently have thermally thin and leaky boundaries. Due to the unique design of these compartments, detailed experimental studies were conducted to understand their fire dynamics. This paper presents the ability of FDS to model these under-ventilated steel sheeted fire tests. Four compartment fire tests were modelled with different wall boundary conditions, namely sealed walls (no leakage), non-sealed walls (leaky), leaky walls with cardboard lining, and highly insulated walls; with wood cribs as fuel and ISO-9705 room dimensions. FDS managed to capture the main fire dynamics and trends both qualitatively and quantitatively. However, using a cell size of 6 cm, the ability of FDS to accurately model the combustion at locations with high turbulent flows (using the infinitely fast chemistry mixing controlled combustion model), and the effect of leakage, was relatively poor and both factors should be further studied with finer LES filter width. Using the validated FDS models, new flashover criteria for thermally thin compartments were defined as a combination of critical hot gas layer and wall temperatures. Additionally, a parametric study was conducted to propose an empirical correlation to estimate the onset Heat Release Rate required for flashover, as current knowledge fails to account properly for large scale compartments with thermally thin boundaries. The empirical correlation is demonstrated to have an accuracy of ≈ ± 10% compared with the FDS models.

Ventilation effects on the thermal characteristics of fire spread modes in open-plan compartment fires

Our understanding of fire behaviour and heating conditions for load-bearing structural elements was developed from an immense body of research in small under-ventilated compartment fires. Within the context of contemporary architecture, large open-plan compartments are commonplace, yet understanding of the first principles that define fire behaviour in such enclosures remains limited. Past experiments have revealed that fires in open-plan compartments exhibit three distinct fire spread modes: a fully-developed fire, a growing fire, and a travelling fire. This paper studies the thermal characteristics arising from these fire spread modes and the effects of the ventilation imposed. An experimental analysis of the energy distribution and spatial heating is conducted on a series of large-scale compartment fire tests, with the fire spread mode and ventilation conditions systematically varied. Each fire spread mode is shown to induce significant and characteristic spatial heat distributions. Moreover, the analysis of the ventilation modes shows equivalent thermal loads imposed on the structure in cases where the opening areas are large, and plume flows are dominant despite lower gas temperatures and irradiation. Thus, fires in open-plan compartments pose unique and possibly more severe thermal loading to structural systems, a characteristic not captured by current design fire methodologies.

Semi-empirical model for estimating the heat release rate required for flashover in compartments with thermally-thin boundaries and ultra-fast fires

More than 1 billion people are living in informal settlements and refugee camps where houses are commonly built from thermally-thin materials (e.g. steel/asbestos sheets). In fire safety literature there is insufficient attention describing the required conditions for flashover (e.g. Heat Release Rate needed for flashoverQ˙FO) in such compartments. In this work, Q˙FO and heat fluxes to the surroundings for compartments with thermally-thin boundaries were investigated using eight compartment fire tests built with 0.5 mm steel sheets and four fuel loads. Numerical simulations were conducted to validate FDS for this application, using the heat release rate inside and outside the compartment, the gas layer temperature and the heat fluxes to the surroundings. The validated model was employed to conduct demonstrative sensitivity and parametric studies to understand the heat balance for thermally-thin under-ventilated compartments. It was found that the heat transfer on/from the walls of the compartment is dominated by radiation, in contrast to the compartments with thermally thick boundaries where the wall conduction dominates. The radiative heat transfer coefficient hrad was then resolved numerically and correlated against the gas layer temperature, wall temperatures and the Q˙FO to create a semi empirical correlation for estimating the Q˙FO.

Critical Factors Determining the Onset of Backdraft Using Solid Fuels

Backdraft is an explosive fire phenomenon which typically occurs during fire-fighting activities, occasionally leading to fire-fighter fatalities. Real backdraft incidents involve complex fuel gas mixtures consisting of the products of underventilated burning and pyrolysis following burnout. However, most experimental research into backdraft has used methane gas or flammable liquids as fuel. Some aspects of real backdraft behavior may have been overlooked as a consequence of this simplicity. A reduced scale series of compartment fire tests have been carried out to investigate the critical factors governing the onset of backdraft, using polypropylene and high density polyethylene samples as fuel. It is established that there are critical temperatures for auto-ignition of the pyrolysis gases leading to backdraft which vary with fuel properties. For polypropylene the highest temperature in the compartment must be above 350°C for auto-ignition of the fuel gases, while mixtures in the presence of a pilot source can be ignited down to about 320°C. Backdraft cannot occur when the compartment temperature is below 320°C. For polyethylene, the corresponding temperature for auto-ignition is 320°C. In parallel with these tests, a series of pyrolysis investigations have been carried out using the fire propagation apparatus, with FTIR gas analysis. The observed critical temperatures for backdraft correlate well with the evolved pyrolysis gases. Analysis shows that higher temperatures are required for backdraft when the CO/CO2 ratio is small, and that below the auto-ignition temperature, backdraft can only occur above a CO/CO2 ratio of about 35%. It is concluded that the crucial factors determining whether backdraft occurs or not are the maximum temperature and the CO/CO2 ratio in the compartment, prior to opening the door.

Investigation of Fire Resistance Performance Considering Fire Conditions in Compartments

A fire resistance design has been applied for the safety of the structure in preparation for the fire that occurred in the building. However, there might be a limit to considering the various fire elements in the design. Particularly, for a natural fire curve, it is difficult to evaluate the structure's fire resistance performance through a full-scale fire test. Thus, the standard fire curve, developed based on time-temperature, has been used instead. In a bid to evaluate the fire resistance performance using the natural fire curve, the procedure proposing that the natural fire curve was first developed depending on the fire load and opening area through the fire test in the compartment, which is then equivalently substituted into the standard fire curve with the same fire load value, was proposed in this study. Heat transfer analysis was performed to verify whether the equivalent-substituted fire curve causes the same temperature gain as the natural fire curve. By comparing the two values, a significantly similar value was found around 20℃. Keywords: Fire Compartment Fire Test, Natural Fire Curve, Equivalent Fire Severity

Simulating real compartment fire conditions in a furnace

SummaryIn the United States, wood has been traditionally used in residential construction. However, the combustibility of wood still limits its use as a building material in prescriptive building codes, and to overcome the limitations, performance‐based codes can be used. In order to properly analyze performance‐based designs, more information on the fire performance of materials is required, including fire performance under different fire exposures. The char rate when timber elements are exposed to the standard time‐temperature curve have been well characterized and can be used to determine the fire‐resistance rating. However, much less is known about the rate of char formation under other fire exposures and time‐temperature curves. In this study, we used time‐temperature data from full‐scale compartment fire tests and applied that data in an intermediate‐scale horizontal furnace. By measuring the furnace temperature, fuel consumption, and heat flux during the various tests, we identified that the furnace could closely replicate the shape of a real time‐temperature fire curve from a ventilation controlled compartment. However, the furnace fell short in terms of meeting the peak temperatures at flashover and heat fluxes expected in a real compartment fire.

Contributions on the fire performance assessment of ETICS systems

The Romanian norms and technical regulations do not provide the obligation of compartment fire tests for composite facade insulation systems “ETICS”. Unfortunately, only after these tests can result reliable data on the performance evaluation of ETICS under the effects of compartment fires, and there is still no harmonized European standard requiring such tests (in 2018 the first part of a European project that aims to harmonize the fire exposure test of façades was completed). In this context, researchers from the INCERC Fire Security Research and Testing Laboratory in Bucharest, tested experimentally the exposure to compartment fire of two types of ETICS, according to the test method set out in BS 8414. The climate test conditions of both systems were similar, and after the tests (for the first time in Romania) a series of data were obtained on the behaviour of ETICS under the action of compartment fires. With these results, the Romanian fire research aims to bring its contribution at European level, for the large-scale fire performance assessment of ETICS and the identification of innovative solutions for limiting fire propagation on building facades.

Auto-extinction of engineered timber: Application to compartment fires with exposed timber surfaces

A series of compartment fire tests with multiple exposed timber surfaces have been undertaken to explore the effect of exposed timber on the fire dynamics and the potential for auto-extinction. A test with exposed wall and ceiling achieved auto-extinction after approximately 21min. Firepoint theory is applied using temperature data at the charline, is shown to predict a mass loss rate dropping below the critical value at 20–21min, and thus is successful in predicting auto-extinction. Additional uncertainties caused by delamination are explored, and recommendations for the use of auto-extinction in design are given.

Toxic Combustion Product Yields as a Function of Equivalence Ratio and Flame Retardants in Under-Ventilated Fires: Bench-Large-Scale Comparisons.

In large-scale compartment fires; combustion product yields vary with combustion conditions mainly in relation to the fuel:air equivalence ratio (Φ) and the effects of gas-phase flame retardants. Yields of products of inefficient combustion; including the major toxic products CO; HCN and organic irritants; increase considerably as combustion changes from well-ventilated (Φ < 1) to under-ventilated (Φ = 1–3). It is therefore essential that bench-scale toxicity tests reproduce this behaviour across the Φ range. Yield data from repeat compartment fire tests for any specific fuel show some variation on either side of a best-fit curve for CO yield as a function of Φ. In order to quantify the extent to which data from the steady state tube furnace (SSTF [1]; ISO TS19700 [2]) represents compartment fire yields; the range and average deviations of SSTF data for CO yields from the compartment fire best-fit curve were compared to those for direct compartment fire measurements for six different polymeric fuels with textile and non-textile applications and for generic post-flashover fire CO yield data. The average yields; range and standard deviations of the SSTF data around the best-fit compartment fire curves were found to be close to those for the compartment fire data. It is concluded that SSTF data are as good a predictor of compartment fire yields as are repeat compartment fire test data.

Self-standing Compartment Fire Tests on Sandwich Panels

Self-standing Compartment Fire Tests on Sandwich Panels

Fire protection of light and massive timber elements using gypsum plasterboards and wood based panels: A large-scale compartment fire test

A full-scale compartment fire test was performed to assess gypsum plasterboards and wood based panels as cladding materials for the fire protection of light and massive timber elements. The test compartment was constructed using both the timber frame and the cross laminated timber techniques; a wood crib was used to achieve realistic fire conditions. Temperature measurements and optical inspection evidence suggested that gypsum plasterboards offered adequate fire protection since they did not fail and no charring was observed in the timber elements. A free standing wall inside the test compartment, protected by wood-based panels, partially collapsed. Measured values of characteristic failure times, such as time to failure of fire protection cladding and time to onset of charring, were compared to relevant Eurocode correlations, achieving good levels of agreement. The obtained set of measurements, describing the time evolution of a large variety of physical parameters, such as gas and wall layer temperatures, can be used for validation of relevant advanced fire simulation tools.