Real-scale Fire Research Articles

Experimental Study on the Fire Impact of Ceiling Insulation on CPVC Pipes

Fires igniting within a ceiling space often escalate into large-scale fires because of delayed detection times, rapid fire spread, and difficulties in firefighting operations. This study investigated the effect of combustible insulation materials on CPVC piping in sprinkler systems using real-scale fire experiments. Based on the top floor of an apartment, this study focused on insulation materials with the highest fire load among the combustibles in the ceiling space. A field survey and fire tests were conducted, and the experiments with EPS and XPS insulation revealed rapid flame spread and the complete destruction of the CPVC piping owing to high heat intensity. Even PIR insulation, a fire-resistant material, causes the destruction of CPVC piping located directly above the fire source. This confirms that combustible insulation materials within the ceiling have a significant negative impact on the functionality of the CPVC piping, rendering it incapable of performing its intended functions. Therefore, this study suggests alternatives for enhancing the reliability of automatic fire-suppression systems during fires in ceiling spaces.

Fire Risk Mitigation Strategies for Electric and Hydrogen Vehicle Car Parks

As the use of eco-friendly vehicles, such as electric and hydrogen vehicles, is rapidly increasing, the related infrastructure is also expanding, and they have become common in parking areas. The fire safety design of a car park is based on the existing data of internal combustion engine vehicles; therefore, the characteristics of eco-friendly vehicles must be reflected. This study investigated the heat release rate of internal combustion engine vehicles, electric vehicles, and hydrogen vehicles using real-scale fire test data and analyzed the effects of curb weight and battery capacity. The fire growth rate and maximum heat release rate of electric and hydrogen vehicles were similar to those of internal combustion engine vehicles, except for the batteries and hydrogen gas, which are the energy sources of electric and hydrogen vehicles, respectively. When ignited from the battery of an electric vehicle, the fire grew rapidly. When the thermally activated pressure relief device was activated in the storage vessel of a hydrogen vehicle, the heat release rate instantaneously increased to 14.5 MW. To improve fire safety in car parks, the curb weight and fire resistance structure must be designed to reflect the increase in plastic interior materials and battery capacity of vehicles, and firefighting facilities must be installed based on vehicles with greater fire severity.

Fire Load of Combustibles in Studio-type Housing

The purpose of this study was to determine the fire load values for small-scale housing, specifically studio-type and small-type housing, and to gather fundamental data for fire safety design. To achieve this, we employed fire load-related theories from existing literature and previous studies, conducted a survey on the area and space of small-scale housing, and collected empirical data on the fire load of such housing. Additionally, through real-scale fire experiments, we determined the heat of combustion for furniture and electrical appliances. These experimental results were then compared with theoretical fire load values and empirical data to establish the fire load values of combustibles in small-scale housing. By comparing the empirical data with the results from real-scale experiments, we derived conclusions about the characteristics of areas based on the spatial configuration and compartments of small-scale housing, as well as the methods for inferring the heat of combustion and fire load of combustibles in these settings.

Campo térmico de lajes mistas em situação de incêndio

Abstract Composite steel decking concrete slabs are an important structural member in building construction. Research on its thermal behavior should be developed to understand its fire performance. In this paper, a comparison of the temperature distribution in the cross-section of steel decking concrete slabs subjected to fire is made through three different procedures: (a) standardized analytical, (b) experimental and (c) numerical. The analytical method was the one proposed in NBR 14323 standard. The experimental tests corresponding to eight real-scale fire tests on composite slabs carried out by the authors. The numerical tests were done for the same configurations of the experimental tests and used the FEA software Abaqus. Steel decking temperatures obtained with NBR 14323 methodologies showed good convergence with the experimental and numerical ones. The same was not observed for the concrete, positive and negative rebar.

A Study on Numercalization of Smoke Detector Response Characteristics

This study was conducted to quantify the response characteristics of a smoke detector. The theory on the entrance resistance of a smoke detector was reviewed, and a method for quantifying the response characteristics through the time constant and characteristic length was proposed. To apply the proposed method, a real-scale fire test of paper and wood, as described in the Excellent Quality Certification Test Rules for Detectors, was conducted. The time constant of the smoke detector was classified into three categories and derived. For domestic smoke detectors, the time constant can be reasonably determined based on the smoke peak value in fires that generate grayish white smoke. This study can serve as a reference for further studies on various samples and fire patterns; the expected response characteristics can be inferred when the detector is installed, which will contribute to improving the reliability of the detector.

Assessment of the Performance of FireFOAM in Simulating a Real-Scale Fire Scenario Using High Resolution Data

An assessment of the performance of FireFOAM in simulating a large-scale compartment fire scenario is presented in this study, using the Edinburgh Tall Building Fire Test I (2017) as the basis for evaluation. Different mesh geometries and sizes are tested, and both theory-based and experiment-based validation approaches are employed. The theory-based validation revealed that the implemented finite volumes method is generally conservative, but unaccounted deviations of up to 20% for the heat release rate were observed due to errors in numerically modelling subgrid phenomena, particularly with tetrahedral meshes. In the experiment-based validation, the simulated data showed good agreement with experimental measurements for flow patterns inside the compartment, neutral plane height, and temperatures outside the ceiling jet. However, there were relatively large errors in incident radiation in the hot gas zone, thermal boundary layer transient temperatures, and compartment inflow/outflow velocities. Systematic errors were attributed to deficient heat transfer boundary conditions and under-estimated air entrainment. The study also identified ways to improve run-time efficiency by implementing parallel processing or reducing solid angles in FVDOM, although using large meshes (30 cm and 40 cm cell size) resulted in faster run-times at the cost of accuracy.

Investigating the Impact of Opening Size on Fire Spread Across Vertical Exterior Surfaces

This study examined the risk of vertical fire spread on exterior walls subjected to flame ejection by measuring temperature and heat flux during real-scale fire experiments. The fire experiment was conducted in a mock-up measuring 2.4(L) × 3.6(W) × 2.4(H) m. Wood cribs were used as the combustible material, and heptane as the initial ignition source. The mock-up featured two singular openings of different dimensions, 2.2(L) × 2.0(H) m (#1) and 2.2(L) × 1.0(H) m (#2), on its front side. Temperature and heat flux variations were measured at the upper part (0.0 m) and on the exterior upper wall (0.5 and 1.0 m) of the mock-up. The maximum heat flux was 15.0 kW/m2 at location #1 and 42.4 kW/m2 at location #2. The maximum temperature was 291.0 ℃ at location #1 and 626.4 ℃ at location #2. This study examined the burning rate of the compartment and the impact of the opening size on the radiant heat and temperature of the exterior walls.

Assessing performance of LEDSA and Radiance method for measuring extinction coefficients in real-scale fire environments

Two photometric measurement methods (Radiance method and LEDSA) were compared against the established MIREX measurement apparatus under controlled laboratory conditions to assess their capability of measuring extinction coefficients in real-scale fires on a temporal and spatial scale. LEDSA is a tomographic technique based on direct measurements of light intensity from individual LEDs using commercially available DSLR cameras. By discretizing the domain into horizontal layers with homogeneous smoke density, values of the extinction coefficient can be computed using an inverse model based on Beer Lambert’s law. The Radiance method involves measuring the contrast of light and dark areas in images and/or video footage. It was originally developed to investigate the descent of the smoke layer in high-temperature fire events. In this work, the extinction coefficient was deduced from measurements on a contrast board by a straightforward analytical approach. Both methods were shown to yield similar extinction coefficient results in line with the MIREX for an EN 54-7 TF5 n-heptane fire. The Radiance method is able to generate accurate patterns but not values for a TF2 wood smouldering fire, while LEDSA is generally able to reflect the MIREX measurement values, yet requires higher computational effort.

Lateral distortional buckling of continuous composite beams in fire situation: Experimental and numerical analyses

In continuous steel-concrete composite beams, hogging moments may occur near the internal supports. This type of bending causes compression in the bottom flange, which may buckle laterally in an ultimate limit state known as lateral distortional buckling. Despite the consideration that continuity may result in an economic design, no research had yet been conducted on the possibility of lateral distortional buckling in continuous composite beams in fire situation. This paper presents an experimental and numerical study on the lateral distortional buckling of steel concrete composite beams. Four real scale fire tests were conducted and proved that it may indeed occur. A parametric study was also developed. It has been shown that this buckling mode may lead to a reduction in the strength of composite beams of up to 50% when compared to the plastic moment. It was also noted that this buckling mode is usually accompanied by local buckling, which may occur even in compact sections, leading to a decrease in bearing capacity. These results indicate a need of reviewing the design codes to consider the possibility of lateral distortional buckling at high temperatures, as it may be more than at ambient temperature.

Effects of Fire Plumes From Pine Needles on Small-Scale Fading in Radiowave Propagation

In this article, radiowave fading caused by fire plumes due to the burning of heaps of pine needles is studied. Detailed characterization of the fire impact in terms of excess loss due to the yielded plumes at UHF frequencies, mainly in the L-band, when considering two different ignition sources, is also presented. The implemented small-scale fire scenario is composed of a 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 1$ </tex-math></inline-formula> m metallic grid covered with a 0.6 kg pine needle fuel bed that was placed right above a circular and linear gas burner to mimic an underbrush scenario. The propagation phenomena were evaluated through specific wideband measurements as the fire developed while intersecting the radio path at the antennas’ boresight. Results demonstrate changes in the propagation medium that is strongly influenced by the plume, which ultimately becomes (partly) ionized. Deep fades of up to 12 dB below median levels at specific frequencies during a short period of time, when the fire is more intense, were measured. We also obtained an overall median excess loss due to fire of up to 2 dB in the frequency range from 0.6 to 2 GHz in a relatively short path (below 1 m). A time-domain analysis allowed us to expand these results yielding fading values of the direct component of more than 3 dB in the presence of fire. Extending the findings presented in this article to a real-scale fire scenario, in which median excess loss of more than 20 dB and deeper nulls are ought to be expected, sets the rationale and motivation to pursue future work on the topic, with practical relevance to future mission-critical communication networks planning, such as, but not limited to, LTE Public-Safety and specific 5G use cases.

전력용 변압기의 고장 메커니즘 분석을 통한 실규모 화재폭발 시험 기법 개발

Failures in high voltage power transformers are classified as a kind of disaster accompanied by fires and explosions. It could lead enormous loss of property due to equipment damage and restoration, and black-out of power grid can take place by separating the fault section from the power system. In particular, power facilities including transformers have been intensively installed in Republic of Korea since the 1988 Seoul Olympics. These power equipment is operated for more than 30 years from then. The power transformers in long-term operation are aged and a number of failures tend to increase, therefore, necessity of developing transformer fire prevention and suppression technology is emerging. This paper deals with the development of 154 kV class power transformer real-scale fire test method through its fire and explosion mechanism analysis to advancement fire prevention and suppression technology on power transformer. The test method includes, test items, subjects, facilities, and test site. The established transformer fire mechanism could be applied to develop new investigation method for cause of transformer fire, and real-scale test methodology could be widely utilized for various research such as transformer fire and explosion test, development of its extinguishing technology.

European Yield Model Exponential Decay Constant Modification for Glulam after Fire Exposure

Many real-scale fire tests have been performed on timber connections to analyze the mechanical behavior of timber connections in previous years. However, little research focused on the bending performance of glued laminated (glulam) timber beam bolted connections after fire exposure. In this paper, the three-dimensional numerical model of the glulam timber beam bolted connections was developed and validated by experimental results. The model can simulate temperature evolution in the connections and their mechanical behavior. In the real-scale test, three (3) samples were prepared for a four-point bending test at normal temperature, while another three (3) samples were tested after exposure to a 30-min standard fire and cooled down to normal temperature. The results show the reduction of the load-carrying capacity before and after exposure to the standard fire by 23.9 kN (71.8%), 8.3 kN (26.1%), and 20.2 kN (47.6%) for bolt diameters of 12 mm, 16 mm, and 20 mm, respectively. The numerical model aims to conduct a parametric study and propose the modification of the exponential decay constant, k, for tropical glulam timber to predict the load-carrying capacity of the glulam timber beam bolted connections after exposure to standard fire.

Performance of intumescent fire protection coatings applied to structural steel tension members with circular solid and hollow sections

Intumescent fire protection coatings are used to improve the fire resistance of steel members. Due to slender cross-sections typically used for tension members, high demands are placed on the effectiveness and reliability of the intumescent coatings. This paper describes real-scale fire tests of intumescent coatings applied to steel tension members with circular solid and hollow sections. First, the current regulations for the application of intumescent coatings on steel tension members are discussed. After that, a comparison between the foaming behaviour and failure mechanisms of intumescent coatings applied to steel tension members with different cross-sections and loading conditions is given. Next, the experimental setup and procedure of the performed fire tests are presented. In addition, the influences of various parameters on the performance of the intumescent coating are analysed, including the geometry of the steel profile, dry film thickness of the intumescent coating, load utilisation level as well as the orientation of the member. Based on the theoretical considerations and results of the fire tests, it is evidenced that mechanically loaded fire tests are essential to assess accurately the contribution of intumescent fire protection coatings to the fire resistance of steel tension members with circular solid sections.

Experimental and numerical investigation into the fire performance of glulam bolted beam-to-column connections under coupled moment and shear force

The fire resistance of connection plays a crucial role in the fire performance of timber structures. During the past three decades, massive real-scale fire tests were performed on timber connections to analyse the mechanical behavior of connections under fire situation. Although different loading scenarios was considered in previous timber connection tests, little research focused on the beam-to-column connections loaded with a combination of stress caused by bending moment and shear force. For post and beam structures, when structures undergo large inter-story drift, the interforce at the connection includes not only shear force but also bending moment. In this study, real-scale tests are carried out on bolted beam-to-column connections loaded with coupled bending moment and shear force under normal temperature and ISO fire exposure. Three-dimensional numerical model of the bolted beam-to-column connections are developed and validated by experimental results. The model is capable of simulating the evolution of temperature in the connections as well as their mechanical behavior. The comparison of the rotation-time curve between experimental data and thermo-mechanical model shows comparable tendency. The experiments and numerical models in this study can enrich existed experimental data of glulam connections and can be used to calibrate the design approach for bolted beam-to-column connections under fire exposure.

Experimental Study on the Spread Characteristics of Initial Fires According to Corridor Types

During an accidental fire in buildings, the corridor becomes the path for flame and smoke to spread, exposing the occupants to danger. Therefore, this study conducted real-scale fire experiments using corridors of size 2.4(L) × 10(W) × 2.4(H) m an “L-type” corridor for one-way evacuation and a “T-type” corridor for two-way evacuation to analyze the characteristics of fire according to the shape of corridors. The real-scale fire experiments were conducted in a fire room (2.4(L) × 3.6(W) × 2.4(H) m) with a single opening (2.0(W) × 1.8(H) m). The combustibles used inside the fire room were wood cribs, with a heat release rate of 651.4 kW, in the L-type corridor and chairs, with a heat release rate of 95.7 kW, in the T-type corridor. The temperature inside the corridor was measured during the real-scale fire experiments, and the average maximum measured temperature was 432.1 °C in the L-type corridor and 103.5 °C in the T-type corridor. The experimental results and the ventilation characteristics according to the corridor types were applied to BFD curves to show the process of designing fire growth models according to corridor types.

Post Fire Residual Strength of the Wall-Slab Using Siliceous Concrete.

It is very important to understand the residual performance of a structure for repair, retrofit, and reuse of a building after a fire. In this study, an experiment is conducted on the residual performance of real-scale siliceous aggregates-based reinforced concrete (RC) wall-slab connection (WSC) after the fire, using the simple calculation method (SCM) of standards (Eurocode, ACI, and NIST) for comparison and analysis. A description of the WSC specimen and detailed methods for the experiment are introduced. The fire test is conducted according to the fire scenario by dividing it into one-sided and two-sided heating based on the wall. In the post-fire residual performance test, the load–displacement and moment-deflection angle relationship according to the fire time are derived and discussed. In addition, the residual mechanical properties after the fire are derived for the 35 MPa siliceous concrete used in the wall-slab specimen. The load and moment, derived using SCM, are compared with the experimental results. Our results show that the one-sided heating test result is close to that of Eurocode’s SCM, and the two-sided heating test result is close to that of ACI (NIST)’s SCM. This study provides a database on the residual strength through a real-scale fire test and standard comparison.

Thermal analysis of steel decking concrete slabs in case of fire

The thermal behavior of composite steel-concrete slabs in fire is more or less known, however there are still a lot of different aspects in the fire design methods that need clarification. A comparison of the temperature distribution in the cross-section of steel decking concrete slabs subjected to fire is made through three different procedures: (a) experimental, (b) numerical and (c) analytical methods. The experimental tests corresponding to eight real-scale fire tests on slabs carried out by the authors. These tests have been used to calibrate numerical models for being used with the finite element software Abaqus. The analytical methods were the ones proposed in Annex D of EN 1994-1-2. The analytical steel decking temperatures showed convergence with the experimental and numerical ones. The same was not observed for the concrete, positive and negative rebar and thermal insulation temperatures. A new analytical approach for assessing the negative rebar temperatures and new factors for assessing the thermal insulation performance - alternative to EN 1994-1-2 - are proposed.

An Experimental Study on the Fire Spread Rate and Separation Distance between Facing Stores in Passage-Type Traditional Markets

Real-scale fire experiments were conducted to understand the fire spread characteristics of the major combustibles handled in traditional markets, a space with high fire risk. The major combustibles were selected through field surveys administered at a number of traditional markets. Through real-scale fire experiments, the horizontal fire spread rate according to the maximum heat release rate of major combustibles was examined. In addition, the separation distance to prevent fire spread to the facing store by radiant heat transfer was examined. As a result of the experiments, it was confirmed that the arrangement method of the combustibles causes a large change in the maximum heat release rate, fire growth rate, and fire spread rate. The horizontal fire spread rate showed a linear proportional relationship with respect to the maximum heat release rate regardless of the type of combustibles, and a correlation to define the relationship was proposed. A correlation equation for predicting the separation distance that can prevent fire spread by radiant heat transfer was proposed, and the curve by the correlation equation was in good agreement with the experimental results. Through this study, it is expected that the correlation proposed to examine the horizontal fire spread rate and the separation distance of major combustibles in a traditional market can be usefully used in the design of fire protection systems to reduce fire damage in the traditional market.

Porous Organic Polymers as Fire-Resistant Additives and Precursors for Hyperporous Carbon towards Oxygen Reduction Reactions.

Cyclotriphosphazene (CP) based porous organic polymers (POPs) have been designed and prepared. The introduction of CP into the porous skeleton endowed special thermal stability and outstanding flame retardancy to prepared polymers. The nonflammable level of PNK‐CMP fabricated via the condensation of 2,2′‐(1,4‐phenylene)diacetonitrile (DAN) and hexakis(4‐acetylphenoxy)cyclotriphosphazene (HACTP) through Knoevenagel reaction, in vertical burning tests reached V‐2 class (UL‐94) and the limiting oxygen index (LOI) reached 20.8 %. When used as additive, PNK‐CMP could suppress the dissolving out of PEPA effectively, reducing environment pollution and improving the flame retardant efficiency. The POP and PEPA co‐added PU (mPOP%: mPEPA%=5.0 %: 5.0 %) could not be ignited under simulated real‐scale fire conditions. The nonflammable level of POP/PEPA/PU in vertical burning tests (UL‐94) reached V‐0 class with a LOI as high as 23.2 %. The smoke emission could also be suppressed, thus reducing the potential for flame spread and fire hazards. Furthermore, carbonization of PNK‐CMP under the activation of KOH yield a hyperporous carbon (PNKA‐800) with ultrahigh BET surface area (3001 m2 g−1) and ultramicropore size showing excellent ORR activity in alkaline conditions.

Fire Spread of Thermal Insulation Materials in the Ceiling of Piloti-Type Structure: Comparison of Numerical Simulation and Experimental Fire Tests Using Small- and Real-Scale Models

Large-scale fires mainly due to the ignition of thermal insulation materials in the ceiling of piloti-type structures are becoming frequent. However, the fire spread in these cases is not well understood. Herein we performed small-scale and real-scale model tests, and numerical simulations using a fire dynamics simulator (FDS). The experimental and FDS results were compared to elucidate fire spread and effects of thermal insulation materials on it. Comparison of real-scale fire test and FDS results revealed that extruded polystyrene (XPS) thermal insulation material generated additional ignition sources above the ceiling materials upon melting and propagated and sustained the fire. Deformation of these materials during fire test generated gaps, and combustible gases leaked out to cause fire spread. When the ceiling materials collapsed, air flew in through the gaps, leading to flashover that rapidly increased fire intensity and degree of spread. Although the variations of temperatures in real-scale fire test and FDS analysis were approximately similar, melting of XPS and generation of ignition sources could not be reproduced using FDS. Thus, artificial settings that increase the size and intensity of ignition sources at the appropriate moment in FDS were needed to achieve results comparable to those recorded by heat detectors in real-scale fire tests.