Search Results (46)

Bridge cables composed of 1960 MPa steel wires can be damaged during vehicle fires. Therefore, it is necessary to study the high-temperature mechanical properties of steel wires under load-bearing conditions. In this paper, the mechanical properties and microstructure of 1960 MPa steel wire after stress relaxation and high-temperature annealing treatment at different temperatures are investigated. The results show that the stress relaxation limit is 422 MPa at 325 °C. The tensile strength of the steel wire after stress relaxation is 1975 MPa, which decreases by 5.73% compared with the initial state. When the annealing temperature is 300 °C, the tensile strength of the steel wire is 2044 MPa, accounting for 98.7% of the strength of the steel wire at room temperature. The tensile strength decreases by 9% when the annealing temperature is 400 °C, the steel wire strength decreases at a significantly higher rate. In addition, the spacing of the pearlitic sheet layers increases from 55 nm to 75 nm at the heat treatment temperature of 300 °C~350 °C. A passive fire protection temperature of 275 °C is recommended for cable wires if safer protection standards are considered. Full article

With the growing prevalence of lithium battery electric vehicles, the incidence of fires resulting from thermal runaway in lithium batteries is also on the rise. In contrast to conventional fuel vehicle fires, fires involving lithium battery electric vehicles exhibit distinct differences in fire dynamics, fire loads, and smoke characteristics. These variations impose more stringent requirements on the design of passive fire protection systems within tunnels. To evaluate the fire resistance performance of existing passive fire protection systems under electric vehicle fire conditions, this study first used PyroSim software 2022 (integrating FDS 6.7.9) to establish fire models for combustion engine trucks and electric trucks, comparing the combustion characteristics of both types of fires without insulation lining materials. Based on the electric truck fire model, different insulation lining materials were added. The analysis of the simulation results focused on the impact of the thermal conductivity and emissivity of each lining material on peak tunnel temperatures, aiming to identify the insulation lining material with the best fire resistance performance. The results indicate that the heat release rate, temperature distribution, toxic gas concentration, and smoke propagation of lithium battery combustion engine truck fires are all higher than those of combustion engine truck fires. Among the five insulation lining materials studied, SiO₂ gel material demonstrated superior fire resistance compared to the others. This research provides a scientific and rational basis for tunnel fire protection design and fire response strategies, aiming to mitigate the damage caused by lithium battery electric vehicle fires to tunnel lining structures. Full article

This study investigates fire separation distances as essential means of passive fire protection in building design. The focus is on the inner corner configuration of building exterior walls, which represents the worst-case scenario for façade fire spread outside of a building. The inner-corner configuration appears to increase the intensity of the radiative heat flux due to reflection and reradiation of heat. Comprehensive approaches for determining fire separation distances around the various façade geometries can be found, but none of them is focused on detailed descriptions of the unprotected area in an inner corner. A medium-scale scenario was chosen and was experimentally validated with a radiant panel for a better understanding of heat flux spread. This paper compares the experiment with analytical and numerical models. The analytical model is based on the Stefan–Boltzmann law and the calculated configuration factor as per Eurocode 1. The numerical model combines radiative and convective components of the heat flux because convection is non-negligible near the heat source. Experimental data confirm the prediction based on the numerical and analytical model and show agreement. The final increase in heat flux due to the corner configuration investigated at the medium scale reaches up to 29%. Full article

Steel structures are vulnerable to fire due to the degradation of their mechanical properties at high temperatures, making it necessary to protect them when exposed to high temperatures. This paper presents the results of an experimental research work to characterise the mechanical properties of gypsum-based fire-resistant mortars with and without nano and micro silica particles by destructive and non-destructive tests at ambient temperature. Five compositions were studied: one commercial composition was used as a reference and four were developed in the laboratory. Two were based on gypsum with perlite or vermiculite, and the other two included nano and micro silica particles. Twenty specimens underwent ultrasonic pulse velocity, flexural, and compression tests, while five specimens were tested by the impulse excitation of vibration. Young’s modulus, shear modulus, and Poisson’s ratio were assessed by non-destructive tests, and the flexural and compression strengths were assessed by destructive tests. Additional tests included density and porosity assessments, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. Results indicated that adding nano and micro silica particles posed challenges to the mechanical and physical properties. Despite this, vermiculite compositions showcased superior or similar properties to the commercial composition, while perlite compositions exhibited slightly lower properties. Full article

Soil CO₂ concentration and flux measurements are important in diverse fields, including geoscience, climate science, soil ecology, and agriculture. However, practitioners in these fields face difficulties with existing soil CO₂ gas probes, which have had problems with high costs and frequent failures when deployed. Confronted with a recent research project’s need for long-term in-soil CO₂ monitoring at a large number of sites in harsh environmental conditions, we developed our own CO₂ logging system to reduce expense and avoid the expected failures of commercial instruments. Our newly developed soil probes overcome the central challenge of soil gas probes—surviving continuous exposure to soil moisture while remaining open to soil gases—via three approaches: a 3D printed housing (economical for small-scale production) following design principles that correct the usual water permeability flaw of 3D printed materials; passive moisture protection via a hydrophobic, CO₂-permeable PTFE membrane; and active moisture protection via a low-power micro-dehumidifier. Our CO₂ instrumentation performed well and yielded a high-quality dataset that includes signals related to a prescribed fire as well as seasonal and diel cycles. We expect our technology to support underground CO₂ monitoring in fields where it is already practiced and stimulate its expansion into diverse new fields. Full article

Due to the irreversible nature of the consequences of fire, fire protection is a major challenge and source of problems for all types of built heritage. This study aims to establish sustainable fire protection technology strategies by generalizing fire prevention and control technologies and measures against extended burns. This study aims to explore Macau’s industrial heritage’s historical development and technological applications in the field of fire protection using literature analysis, field investigation, and spatial information visualization methods. It will be carried out using the industrial heritage of Macau as the object and systematic analyses from the screening and processing of fire protection historical data, fire risk assessment, and the migration of fire protection focus. The results show that (1) the fire protection of the industrial heritage of Macau has gone through a total of three phases: passive fire protection, transition of fire protection methods, and active fire protection, and the relied-upon fire protection technologies have been iterated and renewed continuously during this period. (2) When the fire load factors of industrial heritage increase, the fire vulnerability assessment substantially changes, and the center of gravity of heritage fire protection shifts from controlling the scope of disaster to reducing the fire risk. (3) The construction of a suitable and effective ecological model of fire protection technology can provide appropriate fire protection solutions for the preservation and reuse of Macau’s industrial heritage in a complex cultural context. Therefore, this study will help to solve the current dilemma of sustainable application and development of fire protection technology for industrial heritage. This study hopes to provide ideas and strategies for reference on industrial heritage fire protection issues in the development of similar world heritage cities. Full article

Indoor air quality (IAQ) has a significant impact on human health, as people spend 90% of their time in various indoor environments. Therefore, research on IAQ is extremely necessary. However, current research on traditional Qiang residences in western Sichuan mainly focuses on the indoor thermal environment and heritage protection, with relatively little attention paid to IAQ. This study investigates the IAQ of traditional Qiang residences in western Sichuan, which have open fire pits as the core of daily life, exploring the impact of passive renovation strategies on the indoor air quality. Using simulation methods, this study employs passive strategies, such as increasing the size of windward windows, changing ventilation methods, relocating the fire pit, and enlarging interior partition openings, to improve and optimize the IAQ through natural ventilation. The results show that when the windward window sizes are 0.8 m × 1.9 m and 0.7 m × 1.55 m, the reduction in the indoor CO₂ concentration is the greatest, with a maximum decrease of 0.024% at the 1.5 m plane. This paper proposes passive renovation strategies to improve the indoor air quality of Qiang residences in western Sichuan. These strategies effectively enhance the indoor air quality of Qiang residences and address the research gap on indoor air quality in regional Qiang residences in western Sichuan. The insights and methods presented contribute to the improvement of the indoor air quality in traditional buildings and support the sustainable development of traditional architecture. Full article

Jet fires are the second most common fire scenario after spill fires. This type of fire is characteristic of gas and gas–oil fires occurring on oil platforms and gas production and processing plants. The consequences of such fires are characterized by high material damage; this is associated with extensive networks of technological communications, since there is a high density of technological facilities and installations in the territory where these fires occur. At such facilities, there is a large number of steel structures, which under the action of high temperature quickly lose their strength and deform. To protect steel structures in the oil and gas industry, fire protection is used, which consists of different types: boards in the form of flat plates, plasters, and epoxy paints. This paper compares three types of fire protection materials for steel structures under jet fire: board fireproofing, plaster composition, and epoxy coating. When comparing the efficiency in jet fire, cement boards were found to be the best. However, despite the better fire protection efficiency, their low application is expected due to their massiveness and the high cost of such protection and the difficulty of installation. Nevertheless, the development of fire depends on the place of its origin, the size of the initial fire zone, and the stability and massiveness of the metal elements of the vessel structure or the structure of the boards on which the equipment can be placed. Therefore, it is necessary to take these factors into account when selecting fire protection and to apply it depending on the required fire resistance limits of structures, which should be determined depending on the fire development scenarios. Full article

Lightweight concrete exhibits many advantages over traditional concrete such as lower density and thermal conductivity and an easier, cheaper, less energy-consuming manufacturing process. In order to extend its applications, there is a need to study its behavior in fire situations. Due to that, the aim of this study was to assess the fire resistance of foam concrete, depending on its thickness and the foaming process applied. Fire resistance was assessed according to EN 1363-1. The results indicate the usefulness of foam concrete in terms of isolating fire temperatures for discontinuous partition filling that are consequently a real alternative to dedicated solutions in the field of passive fire protection. The density of foam concrete was shown to have a large effect on the ability to insulate fire temperatures with a standard material preparation process. It was also noted that changing the method to continuous foam feeding may result in the achievement of similar values while maintaining foam concrete low density. Full article

Safety-specific passive leadership has been negatively linked to diminished safety outcomes, including safety behaviors. However, this relationship is not fully understood. Research has not fully examined mediating factors that may be influenced by passive leadership, which then influence safety behaviors. Research among firefighters in this context is particularly absent. As such, this study aimed to examine relationships between safety-specific passive leadership, stress, anxiety, and compliance-oriented safety behavior outcomes among 708 professional firefighters. A path analysis was completed. The hypothesized model fit was very good and hypothesized relationships were confirmed. Safety-specific passive leadership was positively, significantly associated with increased firefighter stress perceptions and stress was positively, significantly associated with anxiety. Anxiety was negatively, significantly associated with both safety compliance and personal protective equipment behavior. This study has implications for researchers and practitioners. The findings emphasize the importance of active leaders in the fire service as passive leadership in the context of safety is distressing, which results in anxiety and ultimately diminished safety behavior outcomes, which could place firefighters at risk for injuries, illness, or death. Full article

The accumulation of thermal energy in the form of latent heat of phase transition using phase change materials (PCMs) is one of the most attractive and studied research areas with huge application potential in both passive and active technical systems. The largest and most important group of PCMs for low-temperature applications are organic PCMs, mainly paraffins, fatty acids, fatty alcohols, and polymers. One of the major disadvantages of organic PCMs is their flammability. In many applications such as building, battery thermal management, and protective insulations, the crucial task is to reduce the fire risk of flammable PCMs. In the last decade, numerous research works have been performed to reduce the flammability of organic PCMs, without losing their thermal performance. In this review, the main groups of flame retardants, PCMs flame retardation methods as well as examples of flame-retarded PCMs and their application areas were described. Full article

The present research investigates the behaviour of sustainable Self-Compacting Concrete (SCC) when subjected to high temperatures, focusing on workability, post-fire impact resistance, and the effects of fire protection coatings. To develop environmentally friendly SCC mixes, Supplementary Cementitious Materials (SCM) such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBFS), and Expanded Perlite Aggregate (EPA) were used. Fifty-six cubes and ninety-six impact SCC specimens were cast and cured for testing. Fire-resistant Cement Perlite Plaster (CPP) coatings were applied to the protected specimens, a passive protection coating rarely studied. SCC (unprotected and protected) specimens, i.e., protected and unprotected samples, were heated following the ISO standard fire curve. An extensive comparative study has been conducted on utilising different SCMs for developing SCC. Workability behaviour, post-fire impact resistance, and the influence of fire protection coatings on sustainable SCC subjected to high temperatures are the significant parameters examined in the present research, including physical observations and failure patterns. The test results noted that after 30 min of exposure, the unprotected specimen exhibited a significant decrease in failure impact energy, ranging from 80% to 90%. Furthermore, as the heating duration increased, there was a gradual rise in the loss of failure impact energy. However, when considering the protected CPP specimens, it was observed that they effectively mitigated the loss of strength when subjected to elevated temperature. Therefore, the findings of this research may have practical implications for the construction industry and contribute to the development of sustainable and fire-resistant SCC materials. Full article

Using lightweight fire-rated board (LFRB) presents cost-effective opportunities for various passive fire protection measures. The aim of the project is to develop an LFRB with enhanced fire resistance, acoustic properties, and mechanical properties. These properties were determined using a Bunsen burner, furnace, energy-dispersive X-ray, impedance tube instrument, and Instron universal testing machine. To fabricate the LFRBs, vermiculite and perlite were blended with flame-retardant binders, and four types of LFRBs were produced. A fire test was conducted to compare the fire-resistance performance of the LFRBs with a commercially available flame-retardant board. The B2 prototype showed exceptional fire-resistant properties, with a temperature reduction of up to 73.0 °C, as compared to the commercially available fire-rated magnesium board. Incorporating nano chicken eggshell into the specially formulated flame-retardant binder preserved the LFRBs’ structural integrity, enabling them to withstand fire for up to 120 min with an equilibrium temperature of 92.6 °C. This approach also provided an absorption coefficient of α = 2.0, a high flexural strength of 3.54 MPa, and effective flame-retardancy properties with a low oxygen/carbon ratio of 2.60. These results make the LFRBs valuable for passive fire protection applications in the construction and building materials industry. Full article

Coating, as one of the significant applications in the building and construction sector, is crucial to prevent steel from reaching critical temperature and fire-induced structural collapse. This article reviews the current use of conventional coatings and assesses the potential use of novel geopolymer coatings on the metal substrate, particularly on the steel structure. The conventional passive fireproofing systems, including cement-based coatings and intumescent coatings, exhibit unavoidable limitations either due to the high thickness and weight or poor thermal and chemical resistance of the coating. Thus, innovations in conventional and novel coatings are constantly developing and growing rapidly. In recent years, geopolymer coatings have attracted much attention due to their higher mechanical strength and excellent resistance to chemicals and heat. Moreover, the green and environmentally friendly characteristics make geopolymer an admirable coating material for many applications. The main challenge that lies in the development of geopolymer coating is the interfacial bonding with the metal structure. Therefore, the influencing factors, including precursor materials, alkaline activator, and curing processes on the adhesion and thermal and chemical resistance of the geopolymer coating have been well explored. The performance comparison between these coatings indicates that geopolymer coating offers a superior mechanical and thermal performance, along with a substantially lower environmental impact compared with cement-based coating. This suggests that geopolymer coatings have great potential for fire protection on steel structures. Full article

Fire risk assessment is important in heritage-village risk management and cultural relics protection. This study aims to establish a fire risk assessment system and model to assess fire safety for heritage villages. Given the complexity and openness of the heritage village system, the nonlinearity of the driving factors, and the dual attributes of residence and tourism, this paper constructs an index system of three aspects: cultural relic value sensitivity, village fire hazard, and evacuation accessibility. Based on ANP and the Bayes algorithm, a hybrid intelligent model is developed, and the index is weighted by combining subjective expert scoring and objective fact statistics. Finally, ArcGIS buffer and network analysis functions are used for grid processing to quantify and evaluate the difference in fire risk distribution in spatial units of heritage villages. We apply this assessment method to Chengkan Village, a national critical cultural relic protection unit. The results reveal that the cluster settlement layout pattern of the ancestral temple buildings plays a decisive role in the fire risk distribution in Chengkan Village; furthermore, the main factors leading to fire risk were analyzed. In Chengkan Village’s core area, the focus of the local government should be on strengthening active fire prevention measures to reduce the probability of fire. In contrast, in the northern and southern areas, it should focus on enhancing passive fire prevention measures to reduce the possibility of significant fires. Full article