Fire Safety Journal最新文献

{"title":"Structural behaviour of tunnels exposed to fire using numerical modelling strategies","authors":"Rafael Sanabria Díaz ,&nbsp;Eva Lantsoght ,&nbsp;Max A.N. Hendriks","doi":"10.1016/j.firesaf.2024.104335","DOIUrl":"10.1016/j.firesaf.2024.104335","url":null,"abstract":"<div><div>Despite the low probability of occurrence, fire events are a major hazard for structures, which can lead to severe socio-economic impact. Although reinforced concrete (RC) tunnels are an important component in transportation infrastructure, their structural behaviour under high temperatures is not yet fully understood. This study investigates the thermo-mechanical response of tunnels subjected to fire using nonlinear finite element analysis (NLFEA). For this purpose, recent experimental tests of large-scale reinforced concrete tunnels with and without fire protection are simulated. Different modelling strategies are discussed, and a detailed description of the constitutive model employed is presented. Then, model-to-model and model-to-experiment comparisons are conducted to identify the advantages and limitations of each approach. The analyses demonstrate the relevance of proper spalling modelling on the tunnel’s temperature distribution. The models also show a good agreement with the experimentally observed damage patterns. Finally, recommendations regarding modelling choices and further research topics are discussed.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104335"},"PeriodicalIF":3.4,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143142068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near-limit downward/opposed flame spread, flame front oscillation and limiting oxygen concentration of B-LDPE tube in normal- and hypergravity","authors":"Yuxuan Ma ,&nbsp;Fangsi Ren ,&nbsp;Taro Takemata ,&nbsp;Shinji Nakaya ,&nbsp;Mitsuhiro Tsue","doi":"10.1016/j.firesaf.2024.104329","DOIUrl":"10.1016/j.firesaf.2024.104329","url":null,"abstract":"<div><div>Near-limit downward flame spread over cylindrical thermoplastic materials under various gravities, oxygen concentrations and opposed flow velocities were investigated experimentally. Black low-density polyethylene tubes with stainless-steel (SS) and copper (Cu) cores were tested. Key parameters, including flame spread rate (FSR) and limiting oxygen concentration (LOC), were measured, and flame oscillations were analyzed using continuous wavelet transforms. Results show that, for SS-core samples, gravity-induced stretch effects reduce the flame temperature, weakening the dripping effect. Dripping seldom occurs near LOC. The trends of FSR and LOC are consistent with blow-off theory. The dominant frequency for oscillatory flame front increases with gravity, while the amplitude decreases owing to shorter dripping lengths. For Cu-core samples, far from extinction, the metal core acts as a heat source, enhancing dripping and FSR, especially in hypergravity. Near the LOC, the Cu-core shifts to a heat sink, thus the flame-flow interaction begins to dominate the FSR. LOC for Cu-core sample is higher than that for SS-core sample, and increases more mildly with gravity and opposed flow. Flame oscillations are more intense in hypergravity due to a stronger dripping flow, but it becomes less important near LOC. This study provides insights into the flammability of thermoplastic material, contributing to fire safety in spacecraft.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104329"},"PeriodicalIF":3.4,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143143025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on the mechanism of surfactant-enhanced water mist suppressing liquid pool fire","authors":"Junsheng Ren ,&nbsp;Wei Peng ,&nbsp;Xiaoyong Liu ,&nbsp;Jinhu Li","doi":"10.1016/j.firesaf.2024.104332","DOIUrl":"10.1016/j.firesaf.2024.104332","url":null,"abstract":"<div><div>Water mist (WM) is widely used to suppress various liquid fires due to its numerous advantages. In order to enhance the suppression ability of WM, additives have become an effective means. In this study, we selected three surfactants as additives for WM, chose ethanol, gasoline, and cooking oil as the suppression targets, conducted comparative experiments, and analyzed the suppression mechanism based on the experimental results. For ethanol pool fires, the most effective inhibitor is 0.01 % FS-51, while the least effective is 0.01 % 1-heptanol for gasoline pool fires, the most effective inhibitor is 1 % CAB-35, while the least effective is 0.01 % 1-heptanol; for cooking oil pool fires, the most effective inhibitor is 1 % CAB-35, while the least effective is pure WM. Based on the suppression results, combined with the fuel characteristics and the surface active agent characteristics, the addition of surface active agents mainly affects the surface tension and foam properties of the WM, the combination of which can better suppress liquid pool fires. Among them, the change in surface tension will affect the specific surface area and momentum of the mist droplets; the foam properties include foaming ability and foam liquid content.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104332"},"PeriodicalIF":3.4,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143143029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A volumetric reaction model for the combustion of moist wood exposed to moderate thermal irradiances","authors":"A. Galgano,&nbsp;C. Di Blasi","doi":"10.1016/j.firesaf.2024.104311","DOIUrl":"10.1016/j.firesaf.2024.104311","url":null,"abstract":"<div><div>An unsteady one-dimensional solid-phase model is formulated and experimentally validated for the glowing combustion of moist wood. Global reactions are considered for wood decomposition and char combustion, with volumetric rates, and a kinetic rate for moisture evaporation. Good agreement is found between the predicted and measured surface temperatures and mass fluxes for thick specimens and/or high heat fluxes. The effects of the moisture content (0–0.75 mass fractions on dry basis), specimen thickness (10–40 mm) and heat flux (18–50 kW/m²) are studied. The cases of combustion, athermic combustion (Δh_c = 0) and pyrolysis are compared. Combustion may cause a pseudo steady state (simultaneous presence of the various zones propagating with roughly constant rates), comprised between short initial and final transients. The conversion time is mainly affected by the reaction heat with minor effects from surface regression. In fact, the characteristic times of athermic combustion and pyrolysis are very close. Compared with pyrolysis, the combustion heat also mitigates the influences of moisture evaporation on the conversion dynamics. The existence and duration of the pseudo steady state are enhanced by high values of specimen thickness and moisture content and external heat fluxes.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104311"},"PeriodicalIF":3.4,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143143026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A deep neural network approach for regional-scale 30-day accumulated urban fire occurrence forecast","authors":"Yang Zhou,&nbsp;Peihui Lin,&nbsp;Naiyu Wang","doi":"10.1016/j.firesaf.2024.104331","DOIUrl":"10.1016/j.firesaf.2024.104331","url":null,"abstract":"<div><div>Efforts to predict and mitigate urban fires require a comprehensive approach that accounts for the complex factors driving diverse fire occurrence patterns. Previous research on urban fire occurrence prediction models has been limited, particularly in addressing both spatial and temporal dynamics effectively. This study bridges this gap by developing a deep neural network (DNN) model specifically tailored to forecast a 30-day accumulated fire occurrence map with a resolution of 2.5 km × 2.5 km for the main urban area of Hangzhou, China. Utilizing a comprehensive 9-year dataset from 2015 to 2023, we develop a novel framework that integrates heterogeneous data, including meteorological factors, urban land use, and preceding daily fire occurrence maps. The framework not only forecasts fire occurrence maps but also provides valuable insights into how different urban land use categories contribute to the spatial patterns of fire occurrences. Our results demonstrate that the model effectively predicts the total count and spatial distribution of fire incidents. Additionally, investigations into urban land use vulnerability reveal that street and transportation zones are particularly susceptible. The proposed methodology addresses the critical need for short-term fire risk forecasting, offering an effective decision-support tool for local fire departments to implement fire risk mitigation strategies.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104331"},"PeriodicalIF":3.4,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143142067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling study on the pyrolysis kinetics of wood composite in the thermally thin regime: The role of heating rates and thermal gradients","authors":"Xiaowen Qin ,&nbsp;Franck Richard ,&nbsp;Benjamin Batiot ,&nbsp;Thomas Rogaume","doi":"10.1016/j.firesaf.2024.104326","DOIUrl":"10.1016/j.firesaf.2024.104326","url":null,"abstract":"<div><div>Pyrolysis of wood composites is a complex process involving reactions with its primary condensed components: cellulose, hemicellulose, and lignin. Thermogravimetric Analysis, within the thermally thin regime, is extensively employed to deduce the kinetics of wood pyrolysis. However, the correlation between heating rates and the pyrolysis kinetics of each component remains unclear, raising concerns about the applicability of these rates in estimating kinetics under varying heating conditions. This paper focuses on examining the influence of heating rate and thermal gradients on the pyrolysis kinetics of wood composite components through a modeling study. The impact on kinetic parameters is analyzed using various chemical mechanisms. These parameters are determined using a model fitting method, which extracts a unique set of kinetics for each heating condition. The study reveals that the heating process interacts significantly with the overall pyrolysis process, and each thermal decomposition reaction of the condensed components is differently influenced by this process. The pyrolysis reaction rate and final mass fraction of the different components vary under distinct heating rates. Notably, higher heating rates tend to shift reactions to higher temperatures, and the interaction between thermal processes and pyrolysis reactions intensifies at increased global heating rates. This paper offers significant insights and considerations for simulating the thermal decomposition of wood on a larger scale.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104326"},"PeriodicalIF":3.4,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143143062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AFFF foam fire extinguishing by gas-permeated spreading and flame barrier with different foaming gases","authors":"Haolan Tan ,&nbsp;Yan Zhang ,&nbsp;Lei Jiang ,&nbsp;Jiaqing Zhang ,&nbsp;Fengju Shang ,&nbsp;Kaiyuan Li ,&nbsp;Yunpeng Yang","doi":"10.1016/j.firesaf.2024.104330","DOIUrl":"10.1016/j.firesaf.2024.104330","url":null,"abstract":"<div><div>Currently, there is a lack of delicate research on flame suppression by foam spreading on the fuel surface. In this study, we propose a new method of varying the foaming gases to control the foam spreading rate on oil surfaces. The kinetic process of foam extinguishing with various gas-liquid ratios is investigated. In addition, the synergistic effect of gas-permeated spreading and flame barrier on the extinguishing efficiency was examined. The results indicate a positive correlation between the extinguishing efficiency and the flame-free spreading rate of CO₂ &gt; He &gt; Ar &gt; N₂ &gt; Air. The extinguishing efficiency decreases with increasing gas-liquid ratio, while the 6:1 ratio leads to a 59% increase in extinguishing time compared to 4:1, and a 90 % increase compared to 1:1. The consumption of foam by the flame enhances as the flame-free spreading rate decreases. The flame consumes over 80% flame-free spreading rates of Air and N₂ foams, leading to fast foam front consumptions by the flame and poor extinguishing performances. Gas permeation in the foam film exacerbates the bubble coalescence and foam drainage, enhancing the foam spreading performance while reducing the foam stability. The foam spreading induced by gas permeation plays a decisive role in spreading rates and extinguishing efficiency, whereas the effect of foam stability on extinguishing efficiency is less influential. Increasing the gas permeability and reducing the gas-liquid ratio enhance the overall foam mobility. Hence, the spreading rate and extinguishing efficiency increase with gas permeability. An empirical model expresses the relationship between extinguishing time and flame-free spreading rate, underscoring the decisive role of foam spreading in the fire extinguishing process.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104330"},"PeriodicalIF":3.4,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143143065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating backdraft phenomenon generated from a wood fuel through a holistic approach","authors":"Ryan Falkenstein-Smith,&nbsp;Thomas Cleary","doi":"10.1016/j.firesaf.2024.104324","DOIUrl":"10.1016/j.firesaf.2024.104324","url":null,"abstract":"<div><div>This work examines backdraft phenomenon generated from a wood fuel assembled into a crib structure. Twenty-six backdraft experiments were conducted in a reduced-scale enclosure to determine components that influence the ignition and deflagration required for backdraft phenomenon. A wide range of heat release rates before the enclosure’s isolation time was implemented in the experimental campaign, spanning from 88 kW <span><math><mo>±</mo></math></span> 8 kW to 216 kW <span><math><mo>±</mo></math></span> 19 kW. The duration of the isolation time, at which the compartment remains closed before an anticipated backdraft event, was also modified between 120 s, 210 s, and 300 s to determine their effect on critical parameters. To account for the complexity of the produced pyrolyzate, a second-generation phi meter was utilized to measure equivalence ratios in the upper and lower regions of the compartment. Temperature and oxygen, carbon dioxide, and carbon monoxide concentration measurements were also obtained at various locations within the reduced-scale enclosure. Time-averaged temperature and oxygen concentration measurements were compared to similar measurements in other works, highlighting limitations in identifying universal conditions conducive to backdraft. Time-averaged equivalence ratio measurements greater than 5 in the upper region of the enclosure were found to signify the occurrence of backdraft, suggesting that its likelihood is associated with the distribution of vapor fuel and oxygen. A logistic regression model was implemented to examine how parameter differences in the compartment’s upper and lower regions contribute to backdraft occurrence. A probability threshold for the backdraft phenomenon between the temperature and vapor fuel ratios in the upper and lower regions of the compartment is established. Spatial ratios of temperature and vapor fuel fraction are compared against each other using the logistic regression model to comment on the incoming flow of the gravity current and residing fuel concentration within the compartment prior to an anticipated backdraft event. A further evaluation of the probability threshold using the backdraft ignition time suggests that the distribution of temperature and fuel affects the gravity current velocity, mixing time, and eventual combustion of incoming air.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104324"},"PeriodicalIF":3.4,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143142499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Progressive collapse behavior of geometrically similar RC frames at ambient and elevated temperatures","authors":"Dongqiu Lan ,&nbsp;Liu Jin ,&nbsp;Yaowen Yang ,&nbsp;Kai Qian ,&nbsp;Renbo Zhang ,&nbsp;Jian Li","doi":"10.1016/j.firesaf.2024.104325","DOIUrl":"10.1016/j.firesaf.2024.104325","url":null,"abstract":"<div><div>Due to limitations in laboratory capacity, investigations of the resistance of reinforced concrete (RC) frames against progressive collapse often rely on scaled specimens. However, the ability of scaled specimens to accurately reflect the collapse-resistant behavior of real structures is uncertain. Particularly in fire scenarios, the fire resistance of specimens of varying scales fails to maintain a similar relationship in terms of fire resistance. To shed light on this issue, a series of scaled models of RC beam-column assemblies were established to investigate the similarity relationship in progressive collapse resistance of RC frames under both ambient temperature and fire conditions. Numerical findings indicate that the failure of RC frames experiencing minor fire-induced damage is governed by rebar fracture at the beam ends near the side columns, whereas RC frames suffering significant fire-induced damage fail because of rebar fracture at the top rebar cut-off point. Increased fire duration results in a notable reduction in load capacity due to changes in failure modes. While the structural behaviors of scaled RC frames under ambient temperature comply with theoretical geometric similarity criteria, this is not the case under fire conditions. Therefore, a time scale was proposed to build the similarity relationship for fire-exposed RC frames.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104325"},"PeriodicalIF":3.4,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143143024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Smoke movement and stratification of tunnel fires under coupled effects of rainfall and ventilation","authors":"Dia Luan ,&nbsp;Tianyang Chu ,&nbsp;Jakub Bielawski ,&nbsp;Chuangang Fan ,&nbsp;Wojciech Węgrzyński ,&nbsp;Xinyan Huang","doi":"10.1016/j.firesaf.2024.104323","DOIUrl":"10.1016/j.firesaf.2024.104323","url":null,"abstract":"<div><div>This study investigates the smoke movement and stratification characteristics of tunnel fires under coupled effects of rainfall and ventilation through a series of reduced-scale tests. Results show that the smoke movement is affected by both ventilation and rainfall-induced airflow. The smoke tends to move downstream of the dominant airflow. As the increase in ventilation velocity, the height of the downstream smoke layer decreases. Conversely, as the rainfall intensity increases, the height of the upstream smoke layer decreases. Forced shear airflow consistently disrupts the smoke stratification downstream of the flow, whether induced by ventilation or rainfall. Although strong ventilation is capable of controlling smoke downstream, it may destroy the downstream smoke stratification. Compared to critical velocity, the confinement velocity is more suitable for tunnel smoke control as it maintains the stability of downstream smoke and thus can be applied in the early stage of fires. The confinement velocity is found to be 0.73 times the critical velocity. A model of the confinement velocity under the effect of rainfall is established. Findings are helpful in emergency rescue and evacuation of tunnel fires under rainfall conditions.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":"152 ","pages":"Article 104323"},"PeriodicalIF":3.4,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143142495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}