Fire

Recent catastrophic bridge fire incidents have highlighted the critical need for effective post-fire assessment of bridges, thereby challenging the dominant practice of complete replacement following these destructive events. This study investigates the post-fire performance of bare, isolated, and Carbon Fiber Reinforced Polymer (CFRP)-repaired Reinforced Concrete (RC) bridge columns under single-unit truck impact followed by air blast. This extreme loading scenario was deliberately selected given the increased vulnerability of bridge columns to this loading scenario in the recent few years. Three-dimensional Finite Element (FE) models of the structural system and surrounding environment were developed and validated in LS-DYNA. The effectiveness of two in-situ retrofitting schemes in mitigating damage and enhancing structural integrity of three column diameters under the selected multi-hazards was assessed. Results demonstrated that wrapping the bottom half of the column height prevents shear failure and significantly reduces the damage under the coupled impact and blast. In contrast, employing a combination of CFRP bars and externally bonded sheets showed limited enhancement on post-fire impact and blast performance. This study provides critical insights into the feasibility and efficacy of retrofitting bridge columns that have experienced fire, thus laying the groundwork for the reconsideration of current design and rehabilitation protocols. Full article

Lithium-ion batteries (LIBs) have come to hold ever greater significance across diverse fields. However, thermal runaway and associated fire incidents have undeniably constrained the application and development of LIBs. Consequently, gaining a profound understanding of the reaction mechanisms of LIB electrolytes during thermal runaway is of critical importance for ensuring the fire protection of LIBs. In this study, quantum chemical calculations were employed to construct oxidation reaction models of electrolytes, and a comprehensive summary of the sources of fire gas generation during the thermal runaway of LIBs is presented. During the sequence of oxidation reactions, the -COH functional group emerged as the most critical intermediate product. Under conditions of low oxygen availability, it was prone to decompose into CO, whereas in the presence of sufficient oxygen, it could undergo further oxidation to form -COOH and subsequently decompose into CO₂. Moreover, the reaction chains associated with electrolyte oxidation were found to be highly intricate, characterized by multiple branches and a wide variety of intermediate products. Furthermore, an in-depth analysis was carried out on the generation mechanisms of several typical fire gases. The analysis revealed that CH₃OH and C₂H₅OH could be considered as the characteristic products of the oxidation reactions of DMC and DEC, respectively. It is anticipated that this research will provide a robust theoretical foundation for elucidating the complex reactions involved in LIB fires and offer reaction models for fire simulation purposes, thereby contributing to the enhancement of the safety and reliability of LIBs in various applications. Full article

The quantity, quality, and accumulation rate of plant litter play a key role in forest floor flammability and, by extension, fire regimes. The varying foliage properties of different tree species also determine litter’s decomposition and its accumulation on the forest floor. The removal of litter by soil fauna, i.e., bioturbation, depends on both the dominant tree species and the successional stage of the forest stand. This research involved laboratory mesocosm experiments aiming to determine the effects of litter quality and earthworm activity on the flammability of the forest floor material at different successional ages. The mesocosms simulated the planting of four tree species (the broadleaf species Alnus glutinosa (L.) Gaertn. (Black alder) and Quercus robur L. (English oak) and the conifers Picea omorika (Pančić) Purk. (Serbian spruce) and Pinus nigra J.F. Arnold (Austrian pine)) at a reclamation site near Sokolov (NW Czechia). The mesocosms contained litter from these different tree species, placed directly on overburden soil (immature soil) or on well-developed Oe and A layers (mature soil), inoculated or not inoculated with earthworms, and incubated for 4 months. The surface material in the mesocosms was then subjected to simulated burn events, and the fire path and soil temperature changes were recorded. Burn testing showed that litter type (tree species) and soil maturity significantly influenced flammability. Pine had longer burning times and burning paths and higher post-burn temperatures than those of the other tree species. The immature soil with earthworms had significantly shorter burning times, whereas in the mature soil, earthworms had no effect. We conclude that earthworms have a significant, immediate effect on the litter flammability of immature soils. Full article

Small bookstores constructed before the 1970s have a high fire risk in the context of the revitalization of historical buildings; while the setup of simple sprinklers is an effective and cheap method of extinguishing fires, the parameters of the sprinklers are uncertain. In this study, small bookstores in Beijing were selected, and physical combustion experiments with/without a sprinkler system were carried out following the provisions of the Code for the Design of Sprinkler Systems. After the experiments, an FDS model was set up using fire dynamics software. The results show that the total heat release rate (HRR) of books and desks is related to the square of time, with a coefficient of 2.528 × 10⁻⁶, and the maximum heat release rate is 40 KW. Unlike the standard test, the physical combustion experiment is significantly affected by the space. According to numerical simulations, when the sprinkler flow velocity is 60~100 L/min, the water consumption of the sprinkler is 195~218 L. This study lays the foundation for the analysis of the combustion characteristics of small bookstores and provides data support for the installation of simple sprinkler systems in small bookstores. Full article

Lithium-ion batteries (LIBs) are widely used as energy storage units in electric vehicles, mobile phones, and other electric devices due to their high voltage, large capacity, and long cycle life. Lithium-ion batteries are prone to thermal runway (TR), resulting in fires and explosions, which can seriously hinder the commercial development of LIBs. A series of safety methods has been studied to prevent TR of LIBs. The safety methods for suppressing TR in LIBs were reviewed, including safety equipment method, material modification method, thermal management method, and cooling method. The mechanism, advantages and disadvantages, and future applications of the TR suppression method are discussed. The effectiveness of the proposed safety method was evaluated through technical analysis and experimental testing, and the inhibitory effects of different safety methods on battery TR were summarized. The future trend of suppressing TR is discussed by summarizing and generalizing existing technologies for suppressing thermal runaway. This study provides a reference for exploring more effective methods to mitigate TR in the future. Full article

Channel fire poses a great threat to personnel safety and structural strength, in which the temperature profile is worthy of attention. In this paper, the longitudinal temperature profile of a ceiling jet induced by a wall-attached fire with different channel slopes was experimentally investigated using a 1:8 reduced-scale channel. The results show the following: (1) For channel fire with a horizontal ceiling, the influence of the burner aspect ratio and source-ceiling height on the temperature profile is monotonous in the cases considered in this work. With a larger burner aspect ratio and larger source-ceiling distance, more ambient air could be entrained; hence, the longitudinal temperature under the ceiling decays faster. (2) For channel fire with an inclined ceiling, when the burner aspect ratio and source-ceiling distance remain constant, the asymmetric entrainment induced by the flame under larger channel slope leads to more hot smoke being transported upstream. Consequently, the temperature profile is not symmetric, with higher temperatures upstream and lower temperatures downstream. (3) Combining the influence of the burner aspect ratios, source-ceiling distance, and burner aspect ratio, the characteristic length scale was modified. Based on this, a model describing the ceiling temperature profile was proposed and then verified with previous data. Full article

Fire-driven land cover change has generated a paradox: while habitat fragmentation from agriculture, livestock, and urban expansion has reduced natural fire occurrences, human-induced ignitions have increased wildfire frequency and intensity. In northern Colombia’s Magdalena Department, most of the territory faces moderate to high wildfire risk, especially during recurrent dry seasons and periods of below-average precipitation. However, knowledge of wildfire spatiotemporal occurrence and its drivers remains scarce. This work addresses this gap by identifying fire-prone zones and analyzing the influence of climate and vegetation in the Magdalena Department. Fire-prone zones were identified using the Getis–Ord Gi* method over fire density and burned area data from 2001 to 2023; then, they were analyzed with seasonally aggregated hydroclimatic indices via logistic regression to quantify their influence on wildfires. Vegetation susceptibility was assessed using geostatistics, obtaining land cover types most affected by fire and their degree of fragmentation. Fire-prone zones in the Magdalena Department covered ~744.35 km² (3.21%), with a weak but significant (τ = 0.20, p < 0.01) degree of coincidence between classification based on fire density, as pre-fire variable, and burned area, as a post-fire variable. Temporally, fire probability increased during the dry season, driven by short-lagged precursors such as Dry Spell Length and precipitation from the preceding wet season. Fire-prone zones were dominated by pastures (62.39%), grasslands and shrublands (19.61%) and forests (15.74%), and exhibited larger, more complex high-risk patches, despite similar spatial connectedness with non-fire-prone zones. These findings enhance wildfire vulnerability understanding, contributing to risk-based territorial planning. Full article

Volunteer firefighters play an important role in the provision of emergency services in Slovenia, where most of firefighters work on a voluntary basis. In many countries, however, volunteering is in decline due to demographic, social and organisational constraints. To maintain this important function, it is important to understand the motivations that drive individuals to join and stay in the volunteer fire service. This study examines the motivational factors that influence Slovenian volunteer firefighters, with a particular focus on fire service support, leadership practices and demographic differences. A quantitative survey was conducted among 244 volunteer firefighters from 22 fire brigades. The data were analysed using descriptive statistics, t-tests, Spearman’s rank correlation and binary logistic regression. The results show that many volunteer firefighters are motivated by the challenge of working under stress and in situations of controlled risk. However, this motivation decreases with age, as older members show less interest in adrenaline-driven tasks. Men show a greater preference for action-oriented tasks, including emergency response, equipment handling and physical engagement. In contrast, women place slightly more emphasis on social connections within the brigade. Volunteers who feel included in decision-making processes and experience cooperative, participative leadership are more likely to remain engaged. Those who are motivated by physical activity are more likely to stay, while those who are primarily motivated by social recognition or status are more likely to leave. These findings contribute to the literature on volunteering in high-risk contexts. Tailored recruitment and retention strategies that take into account age, gender and leadership dynamics can help fire services build more engaged and sustainable volunteer teams. Full article

This paper investigates the dual effects of slope variation and flame interaction on counter-directional flame propagation through numerical simulations of polymethylmethacrylate (PMMA) plates. Critical flame propagation parameters, including flame morphology, flame spread speed, mass loss rate, and radiative heat flux density, were analyzed using the Fire Dynamics Simulator (FDS v6.7.5) software. By comparing counter-directional flames and unilateral flames under varying slope conditions, we evaluated how flame interactions influence flame spread speed and mass loss rate, as well as the role of the view factor in radiative heat flux distribution. Numerical results revealed that the counter-directional fire propagation process on slopes could be divided into four distinct stages based on variations in flame spread rate and mass loss rate. Moreover, we propose a novel method to quantify flame interaction intensity on slopes using flame spread time. These findings enhance the mechanistic understanding of slope-dependent counter-directional flame propagation. Full article

Here, a pure and systematic numerical study is conducted to investigate the detonation propagation in a curvature bend by focusing on the combined effect of curvature and cross-section area with a simple two-step chemical reaction model. In a channel with a small radius of curvature R/λ < 10, the detonation wave presents a periodical failure-reinitiation mode. The detonation wave near the inner wall cannot sustain itself due to the strong curvature effect. In contrast, the compression of the outer wall strengthens the front and can form a transverse detonation wave to re-initiate the failed detonation near the inner wall. In a channel with a large radius of curvature R/λ > 10, the inner wall’s weak rarefaction effect is not strong enough to completely quench the detonation wave. In the same way, the numerical results also show that a large area expansion rate inevitably produces a strong rarefaction effect near the inner wall, causing wave front decoupling and even failure. According to the radius of the curvature and the area increase rate, there are three different modes of detonation propagation: stable, critical, and unstable. By defining a new parameter κ to characterize different detonation modes and by considering both the curvature and area expansion effect, we found that the threshold κ = 0.33 can be used to distinguish the unstable and critical modes. Full article

Wildfires pose significant threats to ecosystems, human lives, and property worldwide. Understanding the behavior of fire spread on sloped terrain is essential for developing effective firefighting strategies and improving fire prediction models. Previous research has successfully demonstrated the accuracy of numerical tools in comparison to laboratory experiments. This study focuses on the influence of terrain slope and wind speed on wildland fire behavior using Computational Fluid Dynamics (CFD) simulations. In the first phase, the numerical model was validated for a 5 m high single Douglas Fir tree under various mesh sizes, yielding heat release and mass loss rates in close agreement with experimental data. The second phase extends the model to simulate a plantation of 66 Douglas Fir trees under varying slopes and wind conditions. The results indicate that a downward slope of 30° reduces the peak heat release rate, while an upward slope of 30° increases it, with wind speed amplifying these effects. Based on these data, a new reduced-order model is proposed to quantify the influence of slope angle on the heat release rate (HRR) in wildland fires. These findings are critical for enhancing predictive fire models and mitigating wildfire risks in complex terrains. Full article

This study presents a novel water mist fire fighting system that integrates water mist sprays and water mist curtains, designed to achieve simultaneous fire suppression, thermal insulation, and smoke control. Three full-scale experiments were conducted under various fire scenarios, and the changes in fire behavior and heat release rate were examined to evaluate the effectiveness of the water mist system in extinguishing fires. Additionally, the spatiotemporal changes in ceiling temperature were monitored to assess the cooling and protective effects of the water mist. The thermal insulation capability of the system was also investigated by detecting the temperature distribution inside the tunnel. Moreover, the smoke conditions upstream and downstream of the tunnel were analyzed to evaluate the smoke-blocking performance of the water mist system. The findings demonstrate that the water mist fire fighting system is highly efficient in attenuating the fire and restricting its progression. Within the water mist spray section, the average ceiling temperature decreased exponentially during both the initial and steady burning phases across all tested fire scenarios. Nonetheless, the smoke-carrying capacity of the water mist spray is limited. Fortunately, the dispersed smoke was diluted by water mist, markedly enhancing visibility and mitigating the impact of smoke on tunnel illumination. Full article

A series of fire experiments were conducted in a 0.5 m × 0.5 m × 0.5 m room, and a single door-like opening was adopted. The height of the openings was 20 cm, and the width of the openings varied from 10 cm to 30 cm, with ventilation factors ranging from 0.0089 m^5/2 to 0.0268 m^5/2. The ventilation constant and combustion efficiency were studied and compared with those of other researchers. It was found that the so-called ventilation constant can hardly be a constant, and it varied greatly, around 0.357–0.436, at different ventilation conditions. The overall combustion efficiency varied greatly at different opening sizes and flow rates, and it was as low as 0.5, even when the flame was ejected. Full article

This paper introduces a novel algorithm—YOLOv8 (You Only Look Once version 8) + FRMHead (a multi-branch feature refinement head) + Slimneck (a lightweight bottleneck module), abbreviated as YFSNet—for lithium-ion battery fire and smoke detection in complex backgrounds. By integrating advanced modules for richer feature extraction and streamlined architecture, YFSNet significantly enhances detection precision and real-time performance. A dataset of 2300 high-quality images was constructed for training and validation, and experimental results demonstrate that YFSNet boosts detection precision from 95.6% in the traditional YOLOv8n model to 99.6%, while the inference speed shows a marked improvement with FPS increasing from 49.75 to 116.28. Although the recall rate experienced a slight drop from 97.7% to 93.1%, the overall performance in terms of F1-score and detection accuracy remains robust, underscoring the method’s practical value for reliable and efficient battery fire detection in fire safety systems. Full article

To investigate the fire prevention and suppression characteristics of coal gangue slurry grouting in goafs and the enhanced regulatory mechanisms of additives, the slurry-forming performance of coal gangue slurry was tested. The effects of heating temperature, grouting thickness, and heating duration on the surface temperature distribution characteristics were analyzed. Temperature-programmed experiments were conducted to examine the influence of various additives on the spontaneous combustion propensity of coal gangue, with a comparative analysis of the inhibitory effects between ammonium polyphosphate (APP) and other additives. The results demonstrate that the prepared coal gangue slurry exhibited no segregation or sedimentation, with a plasticity index consistent with standard grouting material requirements, confirming its superior stability. The central, maximum, and minimum surface temperatures of the slurry showed polynomial functional relationships with heating temperature. Surface temperature initially increased and then decreased with grouting thickness, with 10 cm identified as the critical thickness for temperature transition. Overall, the central, maximum, and minimum surface temperatures increased progressively with rising heating temperatures. In addition, under all tested conditions, the average surface temperature remained below 80 °C for slurries with >5 cm grouting thickness, meeting fire prevention requirements. However, the CO and CO₂ concentrations increased significantly as heating temperatures rose from 100 °C to 300 °C. At grouting thicknesses of 9–12 cm, CO and CO₂ emissions occurred only at 300 °C and decreased with increasing thickness. The coal gangue slurry modified with ammonium polyphosphate (APP) additives exhibited optimal antioxidant performance, significantly suppressing CO and CO₂ emissions, which further diminished with higher additive dosages. The findings of this study provide critical insights into the fire prevention performance of coal gangue slurry grouting and the application of additives in this field. Full article

Wildfires in central-south Chile, consistent with trends observed in other Mediterranean regions, are expected to become more frequent and severe, threatening ecosystems and impacting millions of people. This study aims to enhance wildfire resilience in the central-south regions of Chile through the provision of robust information on current wildfire management practices and comparison with successful alternatives implemented in other fire-prone Mediterranean regions. With this aim, we consulted 55 local stakeholders involved in wildfire management, and alongside a comparative analysis of wildfire statistics and resource allocation in selected Mediterranean regions, we critically assessed different strategies to improve wildfire prevention and management in central-south Chile. The comparative analysis indicated notable economic under-investment for wildfire prevention in Chile. Compared to other Mediterranean countries, Chile is clearly below in terms of investment in forest fire prevention, both in global (public investment) and specific terms ($ ha⁻¹, GDP per capita). The experts consulted included fuel management, governance and community participation, territorial management, landscape planning, socioeconomic evaluation, and education and awareness as key aspects for wildfire prevention. The results of the questionnaire indicated that there was a broad consensus regarding the importance of managing biomass to reduce fuel loads and vegetation continuity, thereby enhancing landscape resilience. Landscape planning and territorial management were also emphasized as critical tools to balance ecological needs with those of local communities, mitigating wildfire risks. Fire-Smart management emerged as a nature-based solution and a promising integrated approach, combining fuel treatments with modeling, simulation, and scenario evaluation based on local and regional environmental data. Additionally, educational and social engagement tools were considered vital for addressing misconceptions and fostering community support. Besides a better integration of rural planning with social demands, this study underscores the urgent need to substantially increase the investment and significance of wildfire prevention measures in central-south Chile, which are key to improving its wildfire resilience. Our work contextualizes the reality of wildfires in central-south Chile and directly contributes to mitigating this growing concern by critically examining successful wildfire resilience strategies from comparable fire-prone regions, complementing ongoing local efforts and offering a practical guide for stakeholders in wildfire management and prevention, with particular relevance to central-south Chile and other regions with similar characteristics. Full article

Fire detection remains a challenging task due to varying fire scales, occlusions, and complex environmental conditions. This paper proposes the CN2VF-Net model, a novel hybrid architecture that combines vision Transformers (ViTs) and convolutional neural networks (CNNs), effectively addressing these challenges. By leveraging the global context understanding of ViTs and the local feature extraction capabilities of CNNs, the model learns a multi-scale attention mechanism that dynamically focuses on fire regions at different scales, thereby improving accuracy and robustness. The evaluation on the D-Fire dataset demonstrate that the proposed model achieves a mean average precision at an IoU threshold of 0.5 (mAP50) of 76.1%, an F1-score of 81.5%, a recall of 82.8%, a precision of 83.3%, and a mean IoU (mIoU50–95) of 77.1%. These results outperform existing methods by 1.6% in precision, 0.3% in recall, and 3.4% in F1-score. Furthermore, visualizations such as Grad-CAM heatmaps and prediction overlays provide insight into the model’s decision-making process, validating its capability to effectively detect and segment fire regions. These findings underscore the effectiveness of the proposed hybrid architecture and its applicability in real-world fire detection and monitoring systems. With its superior performance and interpretability, the CN2VF-Net architecture sets a new benchmark in fire detection and segmentation, offering a reliable approach to protecting life, property, and the environment. Full article

Architectural design seeks to address many challenges, one of which is creating buildings that can quickly and safely evacuate people. Therefore, it is even more important to pay attention to the safety of personnel evacuation. Past disasters have shown that the number of casualties in large sports stadiums can be as severe as those caused by plane crashes. This study uses a case study approach to analyze the evacuation of spectators in a 40,000-seat stadium, comparing the practical application of three performance verification methods. The results indicate that Simulex’s visual dynamic simulation effectively reflects how walking speeds decrease in crowded conditions and how bottlenecks form along evacuation routes. People tend to gather at corners, leading to congestion and uneven distribution of evacuees, with several escape staircases being underutilized. The Guide to Safety at Sports Grounds is suitable for the early planning stages of architectural design, while the “Verification Guideline of Buildings Evacuation Safety Performance-based Design” is better suited for the detailed design phase to ensure compliance with the safety standard of evacuating spectators within 8 min. Compared to planning and designing based solely on regulations or empirical verification formulas, using visualization software allows for effective adjustments to evacuation routes before finalizing the design, balancing crowd flow across all safety exits and improving evacuation efficiency during the operational phase. Full article

In recent years, new fire loads dominated by power banks have caused multiple fire incidents in transportation hubs, posing severe challenges to fire safety. This study uses experimental testing and machine learning regression analysis to explore the heat release rate (HRR) characteristics and influencing factors of box-type power banks under fire conditions. A 1 MW calorimeter was used to conduct four sets of experiments involving a total of 15 box-type power banks, measuring the HRR and analyzing its correlation with oxygen consumption, carbon dioxide generation, smoke temperature, and the fire growth rate. Based on the experimental data, HRR prediction models were constructed using decision tree regression (DT), K-nearest neighbor regression (KNN), and linear regression (LR). The results indicate that the DT model performs best in HRR prediction (MAE = 0.4889, MSE = 0.7414, RMSE = 0.8571, R² = 0.9991), effectively capturing the nonlinear variation patterns in the HRR. The correlation analysis and regression analysis conducted in this study provide crucial data support for fire combustion characteristics research, fire risk assessment, and fire safety optimization. Furthermore, the findings provide crucial data support for research on fire combustion characteristics and data-driven fire risk assessment, which may serve as a foundation for future AI-based real-time fire detection applications. Full article