Fire Conditions Research Articles

Synthesis and Perspectives on Disturbance Interactions, and Forest Fire Risk and Fire Severity in Central Europe

Wildfire risk increases following non-fire disturbance events, but this relationship is not always linear or cumulative, and previous studies are not consistent in differentiating between disturbance loops versus cascades. Previous research on disturbance interactions and their influence on forest fires has primarily focused on fire-prone regions, such as North America, Australia, and Southern Europe. In contrast, less is known about these dynamics in Central Europe, where wildfire risk and hazard are increasing. In recent years, forest disturbances, particularly windthrow, insect outbreaks, and drought, have become more frequent in Central Europe. At the same time, climate change is influencing fire weather conditions that further intensify forest fire dynamics. Here, we synthesize findings from the recent literature on disturbance interactions in Central Europe with the aim to identify disturbance-driven processes that influence the regional fire regime. We propose a conceptual framework of interacting disturbances that can be used in wildfire risk assessments and beyond. In addition, we identify knowledge gaps and make suggestions for future research regarding disturbance interactions and their implications for wildfire activity. Our findings indicate that fire risk in the temperate forests of Central Europe is increasing and that non-fire disturbances and their interactions modify fuel properties that subsequently influence wildfire dynamics in multiple ways.

Climatic Indicators and Their Variation Trends as Conditions for Forest Flammability Hazard in the South of Tyumen Oblast

This study analyzes the forest flammability hazard in the south of Tyumen Oblast (Western Siberia, Russia) and identifies variation patterns in fire areas depending on weather and climate characteristics in 2008–2023. Using correlation analysis, we proved that the area of forest fires is primarily affected by maximum temperature, relative air humidity, and the amount of precipitation, as well as by global climate change associated with an increase in carbon dioxide in the atmosphere and the maximum height of snow cover. As a rule, a year before the period of severe forest fires in the south of Tyumen Oblast, the height of snow cover is insignificant, which leads to insufficient soil moisture in the following spring, less or no time for the vegetation to enter the vegetative phase, and the forest leaf floor remaining dry and easily flammable, which contributes to an increase in the fire area. According to the estimates of the CMIP6 project climate models under the SSP2-4.5 scenario, by the end of the 21st century, a gradual increase in the number of summer temperatures above 35 °C is expected, whereas the extreme SSP5-8.5 scenario forecasts the tripling in the number of such hot days. The forecast shows an increase of fire hazardous conditions in the south of Tyumen Oblast by the late 21st century, which should be taken into account in the territory’s economic development.

Simulations on Evacuation Strategy and Evacuation Process of the Subway Train Under the Fire

This study focuses on the safe evacuation strategy and evacuation process in the subway train under the fires. The subway station evacuation mode should be adopted if the power system of a subway train is normal on fire. While, the tunnel evacuation mode should be adopted if the power system of the train fails because of the effects of fire. Under the tunnel evacuation mode, the direction of tunnel smoke should be opposite to that of most passengers, and passengers should be evacuated toward the fresh wind. By using the numerical simulation software Pathfinder and PyroSim, the passenger evacuation time under different conditions is calculated, and the safety of the evacuation process is evaluated. The results show that the evacuation time of the station evacuation mode is obviously shorter than that of the tunnel evacuation mode. With the same conditions, the evacuation time of the tunnel evacuation mode is 2193 s, which is about four times as much as the evacuation time of the station evacuation mode (526 s). The total evacuation time increases with the total number of passengers and the proportion of older people and children. Under an oil pool fire, which is an extreme fire condition, the fire environment inside the train may reach a level threatening the passengers’ safety before the evacuation is complete, even before the door opens; therefore, special attention should be paid to the safety issues in stage from the fire begins to the evacuation complete.

A Practical Implementation Fire Monitoring Systems Using Fuzzy Methods

Fires are serious disasters that require effective monitoring or control systems to identify risks and respond quickly. In this study, observations were made on the A Practical Implementation Fire Monitoring Systems Using Fuzzy Methods using temperature input from DHT22 sensors, smoke from MQ-2 sensors, and fire history as evaluation variables. The system will classify the temperature as "low", "medium", or "high", smoke as "low", "medium", "concentrated", as well as the history of fires categorized as "low", "medium", "high". The input will be processed using fuzzy logic to generate recommended actions, the actions are classified into "evacuate", "stay away from the area", or "wait for instructions". The implementation of the monitoring system uses the Arduino UNO platform as its base, then the DHT22 temperature sensor, and the MQ-2 smoke sensor to detect fire conditions. Then the test results from the monitoring system will provide recommendations related to more accurate and responsive actions based on actual conditions at the fire site.

Experimental study on the creep performance of Grade 8.8 and 10.9 high-strength bolts at elevated temperatures

High-strength bolts are widely used in beam-column connections which are typically subjected to significant pretension and experience high stress levels. Under fire conditions, high-strength bolts may exhibit noticeable creep deformation due to the combined effects of high stress and high temperature, which may result in significant deformation of the connection, thereby threatening the stability of the structure. This paper reports an experimental study on the creep behavior of Grade 8.8 and 10.9 high-strength bolts at elevated temperatures. A series of tensile tests are conducted on high-strength bolts at elevated temperatures, and varying stress ratios are set based on the yield strength measured form the tensile tests. Test results indicate that the temperature has significant influence on the mechanical properties of Grade 8.8 and 10.9 high-strength bolts. Through the entire temperature range, current specifications significantly overestimate the yield strength of high-strength bolts at high temperatures. At the same temperature, the development of creep strain over time is positively related to the stress ratio. An increase in stress ratio from 0.4 to 0.6 or 0.8 results in a maximum 7.8-time increase in creep strain. The temperature of 500℃ can be regarded as the critical temperature at which the creep effects of Grade 8.8 and Grade 10.9 high-strength bolts should be considered. The mechanical property prediction equations and a modified creep model for Grade 8.8 and 10.9 high-strength bolts were developed, which have high reliability in predicting the high-temperature mechanical properties and creep behavior of high-strength bolts.

Experimental investigation on the effect of natural fire exposure on the post‐fire behavior of reinforced concrete beams using electric radiant panel

Experimental investigation on the effect of natural fire exposure on the post‐fire behavior of reinforced concrete beams using electric radiant panel

Relationships between charcoal property and post fire productivity in the boreal forest

Fire disturbances are increasing under global climate change and ecological transformations of forests are occurring. Specifically, shifts from productive closed-canopy feather moss forests to low-productivity open-canopy lichen (Cladonia spp.) woodlands have been observed in boreal forests of eastern Canada. It has been hypothesized that high severity of fires would be the cause of this change, but this is difficult to validate a posteriori on mature forest stands. Because charcoal properties are affected by fire severity, we have put forward the hypothesis that the amount and physicochemical properties of charcoal (C, N, H, O, ash, surface area) would be different and indicative of a greater fire severity for open-canopy forests compared to closed canopy ones. Our hypothesis was partly validated in that the amount of charcoal found on the ground of closed-canopy forests was greater than that of open-canopy forests. However, the physicochemical properties were not different, albeit a greater variability of charcoal properties for open canopy stands. These results do not allow us to fully validate or reject our hypothesis on the role of fire severity in the shift between open and closed canopy stands. However, they suggest that the variability in fire conditions as well as the amounts of charcoal produced are different between the two ecosystem types. Furthermore, considering the role that biochar may play in improving soil conditions and promoting vegetation restoration, our results suggest that charcoal may play a role in maintaining these two stable alternative ecosystem states.

Numerical Simulation of Flow and Flame Dynamics of a Pool Fire Under Combined Effects of Wind and Slope

Wind has a significant effect on pool fire behavior, which is relevant to many fire conditions, such as wildfires, building fires, and oil transportation fires. Although fire behavior and morphology changes have received considerable attention and been widely researched, there are few works concerning the flow and flam dynamics of pool fire. A large eddy simulation model is adopted to investigate the flow and flame dynamics of a rectangular pool fire considering the combined effects of wind and slope. The results show that, with a wind speed of 0.5 m/s, a flame develops immediately downstream of the fire source and sustains two flanks of plume. Further downstream, the plume starts to rise due to buoyant force. Temperature, velocity, and vorticity distributions show significantly different shapes at different streamwise locations. Near the fire source, the flame is confined to a small region around the fire source. The air circulation downstream shows a cylindrical spiring pattern. When the wind speed increases, the temperature and velocity become more parallel to the surface and their maximum values increase. On the contrary, the temperature fluctuations and turbulent kinetic energy decrease with the wind speed, and they are more frequent near the flame tails.

Designing a Multitemporal Analysis of Land Use Changes and Vegetation Indices to Assess the Impacts of Severe Forest Fires Before Applying Control Measures

Forest fires represent a significant intersection between nature and society, often leading to the loss of natural resources, soil nutrients, and economic opportunities, as well as causing desertification and the displacement of communities. Therefore, the objective of this work is to analyze the multitemporal conditions of a sixth-generation forest fire through the use and implementation of tools such as remote sensing, photointerpretation with geographic information systems (GISs), thematic information on land use, and the use of spatial indices such as the Normalized Difference Vegetation Index (NDVI), the Normalized Burned Ratio (NBR), and its difference (dNBR) with satellite images from Sentinel-2. To improve our understanding of the dynamics and changes that occurred due to the devastating forest fire in Los Guájares, Granada, Spain, in September 2022, which affected 5194 hectares and had a perimeter of 150 km, we found that the main land use in the study area was forest, followed by agricultural areas which decreased from 1956 to 2003. We also observed the severity of burning, shown with the dNBR, reflecting moderate–low and moderate–high levels of severity. Health and part of the post-fire recovery process, as indicated by the NDVI, were also observed. This study provides valuable information on the spatial and temporal dimensions of forest fires, which will favor informed decision making and the development of effective prevention strategies.

New in assessing the fire resistance of reconstructed reinforced concrete ribbed building panel

The article describes the innovative application of a methodology for assessing the design fire resistance of a reconstructed reinforced concrete ribbed floor panel based on the criterion of the occurrence of a limit state based on loss of load-bearing capacity. In this case, the fire resistance limit of a bending element is established without thermal force destruction based on a set of single quality indicators of structural concrete and reinforcing steel, which simplifies engineering calculations and reduces the cost of expensive experiments. The results of a study of the influence of the geometric dimensions of a reconstructed reinforced concrete ribbed panel, the heating scheme of the design section in fire conditions, the placement of the main and additional reinforcement in the design section, the depth of the cores of the main and additional reinforcement and the degree of its fire protection, the thermal diffusion coefficient of structural concrete, the magnitude of the test load on the panel are presented. and the intensity of stress in the rods of longitudinal working reinforcement to the design fire resistance indicator, which is established based on the loss of load-bearing capacity. The use of the new proposed technical solution makes it possible to determine the design fire resistance of a reconstructed reinforced concrete ribbed panel without natural thermal force effects, simplifies engineering calculations, increases the reliability of statistical quality control of reinforced concrete materials and non-destructive tests, and reduces experimental costs.

Constitutive model and deterioration mechanisms of uniaxial compressive behavior for calcium aluminate cement-based UHPC under simulated fire temperatures

Conventional ordinary Portland cement (OPC)-based UHPC is vulnerable to explosive spalling and its performance deteriorates significantly under fire temperatures. In this context, the calcium aluminate cement-based UHPC (AC-UHPC) was prepared by combining the calcium aluminate cement (CAC), recycled brick powder (RBP) and refractory steel fiber (RSF) according to the theory of maximum particle packing in this study, aiming at developing a green, economical and high-temperature resistant CAC-based material. This paper mainly investigated the influence of RSF and exposure temperature on the compressive properties of AC-UHPC, and revealed the degradation mechanism at elevated temperature through the analysis of apparent characteristics and microstructure. The results showed that the compressive strength and strain reached the maximum at 400 °C and 1000 °C, which were increased by 27.57–38.34 % and 2.89–3.44 times respectively compared with that at ambient temperature, while the initial elastic modulus gradually decreased. In the range of 20–400 °C, the phase transformation of hydration products mainly determined the strength of AC-UHPC. above 800 °C, the high temperature stability of RSFs has a significant impact on the residual compressive strength and deformation. At 1200 °C, the compressive strength decreased to 38.81–45.32 % and 24.88–30.41 % of the ambient temperature, respectively. Based on the test results, the prediction equations of compressive strength, peak strain and elastic modulus were proposed, and the empirical constitutive model and damage constitutive model of AC-UHPC considering exposure temperature and RSF volume fraction under uniaxial compression were established. This research offers valuable insights for the design and potential enhancement of green, economical and high temperature resistant CAC-based composites to improve the performance under fire conditions.

Reliability and Fire Performance of Built-up (Battened) Cold-formed Steel Columns: Numerical study

Cold-formed steel (CFS) columns play a crucial role in modern construction due to their lightweight, prefabricated, and recyclable characteristics, contributing significantly to structural safety and reliability. However, unprotected CFS columns lose their load-bearing capacity within 10-15 minutes under fire conditions. This study reviews recent advancements aimed at improving the fire resistance of CFS columns, focusing on factors such as steel thickness, grade, cross-sectional shape, and fire protection materials. Using ABAQUS software, validated against experimental data, parametric studies reveal that thicker sections and higher-grade steels enhance fire resistance, delaying structural failure. Fire protection strategies, such as plasterboard encasement, further bolster safety. The Complex cross-sectional shape demonstrated the highest load capacity (178.51 kN), while G450 steel outperformed other grades in both load capacity and fire resistance. Columns with 1.95 mm thickness provided the longest failure time (73.49 minutes).

Correction: Kubicki, M.; Park, H. Metal-Plated Connections in Sustainable Lightweight Construction: A Weak Link in Fire Conditions? Sustainability 2024, 16, 6923

The authors would like to make the following corrections to the published paper [...]

Impacts of climate change and deforestation on fire risk in the Amazon basin

Fires in the Amazon rainforest are a result of anthropogenic activity in the region. As the Amazon rainforest becomes vulnerable to fire through deforestation and climate change, it is imperative to understand how the fire risk will change in future years—not only for the potential of the forest to become a source of carbon to the atmosphere if burned but also for the potential loss of unique biodiversity and its critical role in regional and global climate. Therefore, we used the Eta regional climate model driven by 3 global climate models to simulate 2 distinct scenarios: one with a high CO2 emission (RCP8.5-DEF15) path and another with a high CO2 emission path and the total deforestation of the Amazon rainforest (RCP8.5-DEFTOT). Combining the multi-model ensemble of temperature and precipitation, we calculated the Keetch-Byram Drought Index (KBDI) and analyzed the results for the dry and wet seasons. In both scenarios, precipitation is reduced and maximum temperature increased. The greatest changes occur during the dry season and with the RCP8.5-DEFTOT scenario. In RCP8.5-DEF15, the KBDI is greatly affected, showing positive anomalies in both seasons. With the addition of deforestation, the fire risk is further exacerbated, thus highlighting the role of the forest in suppressing optimal conditions for fire. Additionally, more than half of the basin area is predicted to experience a high risk of fire in extreme years. Our results emphasize the importance of reducing global emissions and deforestation of the Amazon, given that fire activity could threaten the future of the Amazon rainforest.

A multiaxial thermo-plasticity model for concrete in a transient fire condition

Lateral confinement and high temperature affect the load-carrying capacity of a concrete member significantly. In a fire condition, a concrete member exhibits not only mechanical deformation but also thermal deformation. Therefore, accurately modeling the fire behavior of confined structural concrete is challenging. In this paper, a new three-dimensional thermo-plasticity model for concrete is developed, taking both high temperature and confinement into account. A temperature-dependent yield surface and a non-associate flow rule are formulated. The hardening rules for concrete are proposed as a function of confinement and temperature. The load-induced strain of concrete at elevated temperatures is calculated by using a stress-triaxiality factor to consider the confinement effect. The proposed concrete model is implemented in the user-subroutine (UMAT) of Abaqus, in which Runge-Kutta-England scheme with sub-stepping is used to update stress increment. The accuracy of the proposed model is validated by experiments on concrete specimens, circular concrete-filled steel tubular (CFST) columns, double-skin CFST (DCFST) columns, and concrete-filled double steel tubular (CFDST) columns. It is shown that the developed thermo-plasticity model of concrete accurately captures the behavior of confined concrete at ambient and elevated temperatures and can be incorporated in nonlinear procedures for simulating the fire resistance of composite columns exposed to fire.

Experimental study on fireproof of aviation lubrication oil tank

Abstract This paper presents an experimental study on the fireproof performance of aeroengine lubrication oil tanks. By constructing a simplified lubrication oil tank model and simulating the harsh operating conditions of engine fires, the oil tank was exposed to flames generated by a standard burner for testing. The study monitored and recorded key parameters such as temperature, pressure, flow rate, and phase changes within the tank. The results indicate significant differences in the temperature distribution characteristics of the tank walls under different inlet temperatures and flow conditions. In the rigorous 15-minute flame test, all tests successfully completed the fire verification process.

Observed Associations between Fire Danger and Climate Modes and Their Representation in ACCESS-S2

Abstract The increasing frequency and severity of wildfires in Australia, driven by climate change, pose a significant threat to ecosystems, lives, and property. This study examines the impact of climate drivers, specifically El Niño–Southern Oscillation (ENSO), Indian Ocean dipole (IOD), Southern Annular Mode (SAM), Madden–Julian oscillation (MJO), and two modes of persistent high pressure in the Australia–Pacific region, on extreme fire danger. By analyzing observed and simulated fire danger in relation to these climate drivers, we aim to enhance our understanding of climate–fire mechanisms and contribute to Australia’s bushfire preparedness. Our findings indicate that all assessed drivers influence extreme fire danger, with key influences related to the drivers’ established relationships with rainfall and temperature. El Niño, positive IOD, and negative SAM events generally increase extreme fire danger across most of Australia and in most seasons. The two modes of Australian blocking exhibit similar effects, varying spatially. Specific phases of the MJO have significant seasonal relationships with fire danger. In some instances, increased fire danger is not directly linked to temperature or precipitation changes but rather driven by remote teleconnections, airflow, or pressure anomalies. Evaluating the accuracy of weather and climate forecasting systems in representing these relationships is crucial for the effective prediction and mitigation of fire hazards. The leading Australian climate simulation model effectively reproduces observed relationships but reveals biases in capturing certain aspects of climate variability. Advancements in this field would enhance fire weather forecasts, including those by the Australian Bureau of Meteorology with lead times of up to 4 months. Significance Statement This assessment of climate–fire relationships and modeling accuracy is pivotal in understanding the factors behind severe fire events and improving future predictions and mitigation. Prior research has already established links between elevated fire weather conditions and these climate drivers, highlighting their potential for predicting severe fire events. This study aims to deepen our comprehension of the factors driving severe fire events and facilitate improved bushfire risk management in Australia.

Numerical Study on the Effects of Horizontal Barriers on Fire Behavior in Logistics Facility Racks

In this study, a numerical analysis was conducted to derive the optimal installation conditions for flame-spread barriers within racks, to reduce the damage caused by recurrent fire accidents in logistics facilities. The effectiveness of the fire extinguishing system according to domestic regulations was reviewed to ensure the feasibility of installation of the horizontal barrier. This review revealed that sprinkler systems were ineffective in delaying or preventing the initial spread of fire under certain fire conditions, confirming the need for horizontal barriers. Furthermore, although the installation of horizontal barriers was effective in delaying the initial fire spread, it led to an increase in fire size by blocking the extinguishing water and altering the fire spread path. It was confirmed that deriving the optimal installation conditions for barriers requires the consideration of the interactions between the in-rack sprinkler heads and the surrounding fire extinguishing systems.

Defining a pattern in the loss of integrity by ribbed plates under fire conditions

This paper reports a study aimed at assessing fire resistance of reinforced concrete ribbed slabs at the onset of integrity loss limit state. EN 1992-1-2 lacks calculation methodology for determining the limit of fire resistance of reinforced concrete slabs when the limit state of integrity loss occurs. Scientific works are focused on two limit states of fire resistance: load-bearing capacity and heat-insulating capacity. Experimental tests are criticized because of difficulties in registering signs of the onset of the limit state of loss of integrity, in particular due to the need to control the unheated surface of the ribbed plate during a fire under the action of mechanical load. Therefore, there is no calculation methodology for assessing the fire resistance of reinforced concrete ribbed slabs upon the onset of the limit state of loss of integrity. At the same time, to ensure the safe evacuation of people in the event of a fire, to prevent the spread of fire, as well as to carry out the effective work of rescuers, it is necessary to use building structures with guaranteed fire resistance classes. The paper reports the results of solving thermal engineering and static problems, which relate to the temperature distribution and stress-strain state of the investigated ribbed plate. Conducting research into the fire resistance of reinforced concrete ribbed slabs, taking into account the onset of the limit state of loss of integrity, made it possible to establish the dependence of the fire resistance limit of these structures on the loss of integrity on the level of applied mechanical load. The resulting dependence plot makes it possible to evaluate reinforced concrete ribbed slabs according to the criterion of the onset of the limit state of loss of integrity, which provides an opportunity to determine fire resistance more objectively

A Robotic Teleoperation System with Integrated Augmented Reality and Digital Twin Technologies for Disassembling End-of-Life Batteries

Disassembly is a key step in remanufacturing, especially for end-of-life (EoL) products such as electric vehicle (EV) batteries, which are challenging to dismantle due to uncertainties in their condition and potential risks of fire, fumes, explosions, and electrical shock. To address these challenges, this paper presents a robotic teleoperation system that leverages augmented reality (AR) and digital twin (DT) technologies to enable a human operator to work away from the danger zone. By integrating AR and DTs, the system not only provides a real-time visual representation of the robot’s status but also enables remote control via gesture recognition. A bidirectional communication framework established within the system synchronises the virtual robot with its physical counterpart in an AR environment, which enhances the operator’s understanding of both the robot and task statuses. In the event of anomalies, the operator can interact with the virtual robot through intuitive gestures based on information displayed on the AR interface, thereby improving decision-making efficiency and operational safety. The application of this system is demonstrated through a case study involving the disassembly of a busbar from an EoL EV battery. Furthermore, the performance of the system in terms of task completion time and operator workload was evaluated and compared with that of AR-based control methods without informational cues and ‘smartpad’ controls. The findings indicate that the proposed system reduces operation time and enhances user experience, delivering its broad application potential in complex industrial settings.