Fire Technology最新文献

The structural system of eccentrically braced frames (EBFs) is one of the most common structural systems with a excellent seismic performance in highly seismic areas. This study investigates the performance of this structural system in low-rise buildings. For this purpose, a three-story structure with this structural system is designed, and its behavior is investigated under six different fire scenarios. To analyze the structure under fire loads, the temperature distribution in the members exposed to the fire is first evaluated using the finite element heat transfer analysis method. Using the non-linear time history thermo-mechanics analysis method, the investigated frame is then analyzed, and the displacement and internal forces of the members are obtained. The results of these analyses show that in scenarios where the fire occurs in braced bays, the structure remains stable for a longer time, and the combination of braces and link beams is effective in redistributing the load applied to the adjacent columns.

This study explores how the Fire and Rescue Service can better prepare for solving complex problems in emergencies by using the concept of problems and problem-solving networks. Primary and secondary data from an extensive fire incident were analysed, including semi-structured interviews and incident assessment reports. Complex problems that arise during emergencies can be challenging to define, and solutions can be difficult to identify. However, this study demonstrates that breaking down complex problems into sub-problems can facilitate the identification of what kind of problem-solving network is needed to be able to solve problems in emergencies. Overall, this study contributes to a deeper understanding of the rationale behind problem-solving network in emergency situations and highlights the importance of relationships in problem-solving network to address complex problems during emergencies.

Risk-based design and assessment methods are gaining popularity in performance-based structural fire engineering. These methods usually start by defining a set of hazard scenarios to use as analysis inputs. This approach, proven highly effective for other hazard types such as earthquakes, may not be optimal for fire safety design. Indeed, the strong coupling between the fire phenomenon and structural features enables an ad-hoc design variable selection (and/or optimisation) to reduce fire intensity, making fire scenarios additional design outputs. In addition, such a coupling effect implies that fire scenarios maximising consequences are structure specific. Building on these considerations, this paper discusses the limitations that arise at different analysis steps (i.e., fire-scenario and intensity treatment, identifying fire intensity measures, probabilistic fire hazard analysis, developing fire fragility models, and risk calculation) when using conventional risk-based approaches for design purposes. Furthermore, it compares such approaches with a fire safety design methodology (the Consequence-oriented Fire intensity Optimisation, CFO, approach) that addresses the identified limitations. The potential benefits of integrating the two approaches are also discussed. Finally, the fire design of a simplified steel-girder bridge is introduced as an illustrative example, comparing the consequence metrics and design updating strategies resulting from the two approaches.

Eurocode-2 (EC2) empirical equation for fire resistance of RC columns is very sensitive to the value of column capacity at normal temperature conditions (N_{Rd}). Techniques to determine (N_{Rd}) accurately for eccentric slender columns are difficult and computationally demanding; thus, adopting simplifications leads to unsatisfactory results in many column cases. Another shortcoming of EC2 equation is that it does not include an explicit term regarding the effect of load eccentricity on fire resistance. In this paper, a simplified method, as an attempt to overcome EC2 method defects, is developed to determine the fire resistance of RC columns using fire-resistance-column-curves. A rational numerical model is used to analyze various series of RC columns with different geometric, material, and loading properties at elevated temperatures. The results of the numerical study are utilized to construct different fire-resistance-column-curves from which simplified design equations are developed to predict the fire resistance of fixed- and pinned-end RC columns. The validity of the method is established with the aid of experimental data and it was found that in most cases, there is good agreement between assessed and test columns. It was also found that the proposed equations provide sufficiently safe predictions when appropriate material safety factors are adopted. The applicability of the proposed method to fire resistance design of RC columns is illustrated through numerical examples.

The adoption of timber, specifically cross-laminated timber (CLT), as a primary construction material is gaining traction due to its carbon sequestration capabilities, environmental advantages, and potential for precision manufacturing. However, the combustibility of wood raises legitimate concerns about fire safety in timber-based residential buildings. This paper investigates the fire performance of timber in a residential context, attempting to fill knowledge gaps and outline strategies for improving fire robustness in timber-built dwellings. Through comprehensive experimental studies on residential-type enclosures constructed with CLT panels, this research explores different configurations and the effects of varying degrees of non-combustible protective lining. The findings underscore the significance of considering timber surface exposure and adopting effective encapsulation strategies in CLT buildings. It has been estimated that the exposure of timber walls leads to a proportional increase in heat release rate, corresponding to the area of exposed timber surfaces and their charring rates. Consequently, the external flame has a larger projection, resulting in a much greater heat flux to the façade. Furthermore, threshold conditions for initial flaming self-extinguishment of timber defined in literature of 44.5 ± 1.2 kW/m² have been found to be applicable to the experiments conducted in this research. Finally, it has been observed that partial encapsulation, where the protective lining will likely fall off during a fire, may hinder rather than increase the likelihood of self-extinguishment. This work contributes towards a nuanced understanding of fire dynamics in timber structures, offering insights for safer and more effective design strategies for CLT-based construction.

Aqueous film-forming foam is being phased out due to the environmental impacts of fluorinated surfactants contained in the firefighting foams. To develop an environmentally friendly firefighting foam, it is important to understand the factors controlling the firefighting performance of surfactants. Fuel transport through foam has been considered as a dominant mechanism for foam collapse. Therefore, the impact of fuels (heptane, octane and trimethylbenzene (TMB)) on surfactant microstructure was studied for three different types of surfactants (Capstone, Glucopon, and siloxane) that have applications in firefighting foam. Multiple techniques were used to identify the microstructure and interfacial properties of surfactants with and without exposure to liquid fuel. The ignition time of fuel vapor through foam and solubility of fuel through liquid surfactant solution were measured as well. This work shows fuel solubility has an impact on the surfactant microstructure and interfacial properties. In addition, fuel solubility and vapor pressure affect the ignition time of fuel vapors.

This study is the first part of a larger investigation into the fire behaviour of green façades. In this study, the currently known international research status on this topic is presented and discussed. In addition, the flammability of green façades is investigated through 43 fire tests on a medium scale according to the SBI (Single Burning Item) test method EN 13823. The focus of the investigation was placed on climbing plants. A total of 25 different plant species were investigated. A comparison of the heat release rate of all the investigated vital plants shows similar behaviour. In the course of exposure, there are short peaks in the heat release rate. These peaks are “flare-ups” that occur when parts of the plants dry out due to exposure to the flame and then ignite. The plant species itself had no substantial influence on fire behaviour. Horizontal fire spread occurred to a very limited extent within the investigations of vital plants. They were self-extinguishing. The significant factor in the assessment of flammability is the moisture content of the plants. With dried plants, an abrupt heat release occurs at the beginning. Dried-out plants, as well as unmaintained plants with a high content of deadwood, represent the most critical case.

Graphical Abstract

Providing NFPA 1403 compliant live-fire training can present thermal and chemical exposure risk to instructors and students. To reduce risk, training academies, fire departments, instructors, and standards setting technical committees need more information on how different training fuels used in common training structures can impact the environment in which firefighter training occurs. This study utilized a traditional concrete training structure with multiple compartments to characterize training environments with three different fuel package materials [i.e., low density wood fiberboard, oriented strand board (OSB), and wood pallets]. Exposure risks for a fire instructor located on either the first or second floor were characterized using measurements of heat flux, air temperature and airborne concentrations of several contaminants including known, probable, or possible carcinogens. It was hypothesized that utilizing a training fuel package with solid wood pallets would result in lower concentrations of these airborne contaminants [aldehydes, polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs)] than wood-based sheet goods containing additional resins and/or waxes. Additionally, it was hypothesized that these concentrations would be lower than in the single compartment Fire Behavior Lab presented in a companion manuscript. For all measured compounds other than hydrochloric acid, airborne concentrations were 10 to 100 times lower than in the Fire Behavior Lab. OSB-fueled fires produced the highest median concentrations of total PAHs and VOCs such as benzene, while the pallet fuel package produced the lowest median concentrations of these compounds. These trends generally followed the qualitative visual obscuration created by each fuel. Additional tests were conducted on the OSB-fueled fires with increased ventilation and an alternate means of reducing visibility through smoldering smoke barrels. This OSB experiment with increased ventilation resulted in the highest temperatures in the fire room but the lowest impact on visibility throughout the structure, as well as the lowest overall concentrations of contaminants in this study. In contrast, the smoldering straw-filled smoke barrel created a highly obscured environment (with minimal impact on thermal environment) and some of the highest concentrations of the targeted contaminants of any test. These data may be useful in balancing obscuration for training with potential exposure to thermal stressors and contaminants.

In recent years, electrical fires, which constitute the majority of fire incidents, have become a significant concern. This paper presents a quantitative evaluation of the research on electrical fires from 1993 to 2022, using literature measurement and visual analysis techniques. A total of 2915 publications were collected from the Web of Science database to review and analyze the research progress on electrical fires. In this investigation, the quantitative distribution of literature by year as well as the distributions of main source journals, countries and regions, institutions, and discipline categories were analyzed. Additionally, research hotspots were identified and the knowledge field was mapped using VOSviewer. The results indicated an exponential growth in the number of publications on electrical fires, with Ceramics International emerging as the most prolific journal, having published 79 papers and accounting for 2.5% of the total research. The most active countries in electrical fire research were found to be China, the United States, South Korea, India, Germany, France, and the United Kingdom, with Chinese publications having the most significant impact. The University of Science and Technology of China, Chinese Academy of Sciences, and Tsinghua University are the most productive institutions in the field of electrical fire research; their main research directions include electrical structure, electrical experiment simulation, insulating materials, battery fires, fire extinguishing technology, and detection methods. Further, we observed that the scope of research on electrical fires has expanded from the macro to micro level. Thematic analysis conducted in the last decade has revealed that battery fires and equipment materials have emerged as the primary focus of research in this field. These research findings offer a comprehensive overview of the evolution of research hotspots, which can assist researchers in quickly grasping the research frontiers as well as the overall situation.