Fire and Materials最新文献

Simulating fire and evacuation scenarios is crucial for engineers to assess building safety during fire incidents. Accurate simulations require data on occupants' behaviors, particularly during the pre-evacuation phase as these decisions significantly impact evacuation duration. Gathering comprehensive data from diverse regions while considering cultural and regional variations is necessary to understand how occupants' behavior is influenced. Thus, this study focuses on examining the behavior of Malaysian hotel staff during unannounced fire drill to gain insights into factors affecting their behavior during pre-evacuation stage, such as fire experience, fire alarm, drill participation, fire training, and awareness. The study categorizes the actions performed by the hotel staff into sequences and analyses them based on influencing factors. The findings indicate that instead of immediately evacuating in response to emergency notification, the hotel staff engage in various actions. Most staff members initially investigate or ignore the emergency, resulting in longer pre-evacuation times. Moreover, the results suggest that previous drill participation and high awareness levels contribute to shorter pre-evacuation times. Conversely, previous fire experience, fire training, and fire alarm familiarity have no effect on pre-evacuation time.

In fire safety engineering analysis of sprinkler-protected residential buildings, the maximum heat release rate is a key parameter requiring consideration. Several documents provide advice for estimating the heat release rate of a sprinkler-controlled fire, with a prevailing suggestion that it is fixed upon activation of the first sprinkler. When carrying out deterministic analysis, this requires the engineer to assume fixed fire parameters and consider that sprinklers limit fire growth. To explore these assumptions, the study uses three deterministic models to estimate a sprinkler-controlled maximum heat release rate for a representative apartment layout. The models include Alpert's correlation, a B-RISK zone model and a computational fluid dynamics model in the Fire Dynamics Simulator. These deterministic models are compared to a probabilistic model in B-RISK, where Monte Carlo simulations are used to generate a range of maximum heat release rates from distribution functions for fire and sprinkler properties. An output distribution function is generated with a mean of 296.6 kW and a standard deviation of 503.8 kW, with a lognormal distribution (μ = 5.014, σ = 1.165) estimated as a best-fit. The deterministic models are estimated to sit in the 92–98 percentile range of this function, indicating that common deterministic assumptions are reasonably conservative. The article concludes with suggesting that, for deterministic analysis, a percentile between the 80th and 99th (340–2640 kW) could be qualitatively selected based on the design objectives, building situation and relative consequence of a fire. Further research is needed to establish guidelines for selecting appropriate percentiles across various building scenarios.

Polyethylene (PE) sandwich panels are being increasingly used in external building insulation, but they may also contribute to the upward spread of flames during fires. This work investigates the impact of core thickness and opening height on the combustion characteristics of PE sandwich panels. Small-scale experiments and numerical simulations show that flame stretching and intermittent flames occurr during combustion. The average flame spread height is proportional to the thickness and the opening height, and a dimensionless relationship between the flame height and the characteristic length is established. As the thickness increases, the high-temperature zone within the PE sandwich panels increases. The average mass loss rate is proportional to the thickness and opposite to the opening height. The findings of this study hold crucial theoretical significance for ensuring the safe design of windows and PE sandwich panels in high-rise buildings.

Pressure treated wood (PTW) and wood–plastic composites such as Trex® are popular materials for the construction of decks and other auxiliary structures, which are known to significantly contribute to spread of wildland fires into communities. In this work, representative samples of these materials were studied to determine their pyrolysis and combustion properties to enable simulation of fire growth on the surface of these building products. The pyrolysis property development process followed a well-established hierarchical approach where thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry were used to parametrize kinetics and thermodynamics of the thermal decomposition and combustion, while controlled atmosphere pyrolysis and cone calorimetry tests performed on coupon-sized samples were used to parameterize thermal transport properties and validate performance of the fully parametrized pyrolysis models. PTW decomposition was captured using four sequential reactions with one additional reaction used to model vaporization of water. Trex® board was found to consist of two distinct layers: a thin outer layer and an internal core. The pyrolysis model for this material was constructed using some known properties of high-density polyethylene (PE) and the properties of PTW determined in this work. The outer layer was defined in the model to consist of PE and an inert additive, while the core was defined as a blend of PE and wood particles, which kinetics and thermodynamics of the thermal decomposition and combustion were successfully captured using the model developed for PTW.

This study investigates the combustion behavior, emissions, and aerosol production of four plant species: Laurus nobilis, Cistus monspeliensis, Photinia fraseri, and Cupressus sempervirens. The Heat Release Rate (HRR) and Smoke Production Rate (SPR) were measured, revealing that Cupressus sempervirens had the highest HRR and longest flame duration due to its higher bulk density. Emission Factors (EFs) for key compounds such as CO₂, CO, NO, and aerosols showed significant variation by species. Aerosol analysis indicated that the combustion of all plants primarily emitted fine particles, with the majority being ultrafine particles (PM_0.1), particularly in the 25–130-nm range. Particle size distributions were bimodal in number but monomodal in volume. These findings highlight the impact of plant characteristics on fire behavior and emissions, with significant implications for understanding fire dynamics in wildland–urban interfaces.

Using recycled concrete aggregates (RCA) in concrete has emerged as a promising solution to produce concrete with reduced environmental impact and adequate performance. However, a deeper understanding of the thermal and mechanical behavior of concrete made with RCA is still needed for further application in real structures. The present paper addresses one of the crucial issues for structural concrete: its behavior after exposure to high temperature. Four concrete mixes are studied: a reference concrete made with natural aggregates (NA), two concretes including 40% and 100% of coarse RCA as a direct replacement (DR) for coarse NA, and a concrete made with 100% of coarse RCA relying on a strength-based replacement (SBR). The SBR concrete mix was designed to achieve the same performance (28 days compressive strength and slump) as the reference concrete. All specimens were exposed to temperatures of 200, 400, and 600°C. After cooling, samples were evaluated for residual mass loss, thermal, and mechanical properties. Microstructural quantitative analyses were conducted over several square millimeters to show that interfaces between the old and new cement pastes, peculiar to concrete made with RCA, do not further promote fracture development. The results show that after exposure to high temperatures, the thermal and mechanical performances of concrete made with RCA are reduced in the same manner and extent as in concrete made with NA. When the RCA-based concrete is designed to achieve similar performance as concrete with NA at room temperature (SBR), the residual thermomechanical behavior is similar between both concretes.

Fire accidents in buildings are occurring and claiming thousands of lives each year. Due to various architectural designs, fire hazards would be unique to each building layout. This paper discusses how fire hazard varies with the arrangement of the fuel inside buildings. To comprehensively present the effect of fuel distribution on fire behaviour, results from large-scale experiments, bench-scale experiments, empirical correlations, and numerical studies are provided. In large-scale fire tests, two different cases of wood cribs were tested to demonstrate the effects of porosity on heat generation and fire spread behaviour. Due to the limitations of experimental conditions, the variation in heat release rate attributable to differences in fuel porosity and surface area has been also qualitatively investigated using a cone calorimeter test. To bring the gap between experimental observations and real-word scenarios, a numerical study is also performed. This study further explores the effects of fuel distribution (considering porosity and surface area of fuel throughout the compartment) and ventilation on fire spread beyond the fire compartment. The computational fluid dynamics (CFD) simulations show how the distribution of fuel in different ways can lead fire to spread beyond its origin, as observed in many fire accidents. The paper suggests that designers should consider such critical fire scenarios in performance-based design.

An automobile accident may cause combustion and release large quantities of toxic smoke in tunnels. This article investigates how the heat release rate and fire displacements affect the air entrainment coefficient during smoke one-dimensional motion stage along the tunnel by using a shaft with unpowered ventilation cap for natural ventilation. The results show that the air entrainment coefficient increases with the heat release rate when plug-holing occurs in the shaft. The correlation between the air entrainment coefficient and heat release rate is analyzed by dimensionless analysis and verified using experimental data. Different transverse fire source locations do not significantly affect the temperature distribution during the one-dimensional horizontal spread of smoke. The air entrainment coefficient exhibits no significant difference for different transverse fire source locations, but is lower for a fire closing to the sidewall than for other locations. The ratio of the air entrainment coefficient for a fire source near the sidewall to that for a fire source at the center of the tunnel is 0.76–0.96. This research contributes to a deeper understanding of smoke dynamics in tunnels, which can ultimately aid in the development of strategies to help trapped people escape.

This paper reports on the application of extract from the peels of jackfruit (Artocarpus heterophyllus Lam.) to increase flame retardancy and reduce toxic gaseous emissions from the combustion of cotton textiles. In particular, the results from Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) of treated and untreated samples proved the incorporation of jackfruit peels extract onto the textile substrate, while the results from thermogravimetric analysis (TGA) and standard flammability tests of treated and untreated samples, and their corresponding limiting oxygen index (LOI), proving the flame retardancy effect of jackfruit peels extract on the textile substrate. The textile substrate treated with jackfruit peels extract exhibited excellent flame retardancy, evident by LOI value increasing to 26.8% and samples self-extinguishing within 4.5 s after being removed from the reference flame. In addition, the increase in flame retardancy of treated textile samples also demonstrated good washing durability, even after 30 cycles of standard washing. More importantly, gas chromatography coupled mass spectroscopy (GC/MS) analysis of gaseous emissions from the combustion of samples treated by jackfruit peels extract and by commercial Pyrovatex CP suggested that the use of jackfruit peels extract could help greatly reduce the release of toxic volatile substances, which would pose significant risk to the health of human and the ability of people to safely evacuate from fire accidents. In conclusion, these results have demonstrated the potential of a novel green approach for the fabrication of flame-retardant textiles.

The objective of the study was to alleviate the thermal-moisture comfort (TMC) of phase change material (PCM) thermal protective clothing, while simultaneously enhancing thermal protective performance (TPP) by a drip molding process. Nine types of PCM dripped fabrics were prepared by the drip molding process and served as comfort layers of thermal protective clothing. The TMC and TPP of the fabric systems were measured. A new method was proposed to balance the TMC and TPP of thermal protective clothing. The results demonstrated that the drip molding process marginally weakened the TMC while substantially enhancing the TPP of fabric systems. But the TMCs of the PCM dripped fabrics were far larger than the PCM coated fabric. Specifically, an increase in droplet diameter led to a decline in TMC and an improvement in TPP, whereas an increase in droplet interval resulted in an enhancement in TMC and a decrease in TPP. The findings obtained in this study can be used to engineer fabric systems that provide better protection for heat stress and skin burns.