Fire Safety Journal最新文献

Bench-scale thermomechanical assessment of carbon fibre reinforced polymer C-channels 碳纤维增强聚合物 C 型通道的台架规模热力学评估

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-11-04 DOI: 10.1016/j.firesaf.2024.104285

This study investigates the thermomechanical response of carbon fibre reinforced polymer (CFRP) C-channels using a bench-scale apparatus that combines mechanical loading and radiant thermal exposure. The study aims to assess the behaviour of pre-loaded CFRP C-channels, representative of aircraft sub-structures when subjected to fire conditions. Woven prepreg CFRP C-channels were tested under cantilever point load deflection while exposed to varying heat fluxes. Key aspects examined during the study include failure times, displacement, temperature distribution, and failure modes. The findings reveal that heated, pre-loaded C-channels experience distinct phases of physico-chemical decomposition and mechanical degradation. The mechanical degradation includes upward shear buckling of the horizontal flanges and vertical web, along with outward buckling of the vertical web towards the heat source. The study shows that thermal decomposition and mechanical degradation occur simultaneously, influenced by heat flux intensity. Higher heat fluxes accelerate decomposition and reduce load-bearing capacity, while lower fluxes slow degradation. Displacement data indicates that heat flux intensity significantly affects structural response. Temperature measurements show higher fluxes lead to elevated temperatures and steeper gradients, impacting failure times and modes. Increased temperatures correlate with shorter failure times, and variability in failure times decreases as heat flux rises. These insights are significant for understanding the thermomechanical response of C-channels in aircraft sub-structures. The knowledge obtained can contribute to developing more robust and safer aircraft designs, particularly for components exposed to fire conditions, enabling engineers to establish more precise safety margins for CFRP structures, potentially preventing catastrophic failures and thereby enhancing overall aircraft safety.

本研究使用一种结合了机械加载和辐射热暴露的台式设备，对碳纤维增强聚合物（CFRP）C 型槽的热机械响应进行了研究。该研究旨在评估预加载 CFRP C 型槽在火灾条件下的行为，它代表了飞机的子结构。在悬臂点荷载挠度下对编织预浸料 CFRP C 型槽进行了测试，同时暴露在不同的热通量下。研究的主要内容包括失效时间、位移、温度分布和失效模式。研究结果表明，加热的预加载 C 型槽经历了不同阶段的物理化学分解和机械退化。机械退化包括水平翼缘和垂直腹板的向上剪切屈曲，以及垂直腹板向热源的向外屈曲。研究表明，热分解和机械降解是同时发生的，受热流强度的影响。较高的热通量会加速分解并降低承载能力，而较低的热通量则会减缓退化。位移数据表明，热通量强度对结构响应有显著影响。温度测量结果表明，较高的热通量会导致温度升高和梯度增大，从而影响失效时间和失效模式。温度升高与失效时间缩短相关，而失效时间的变化则随着热通量的升高而减小。这些见解对于了解飞机子结构中 C 型通道的热机械响应具有重要意义。所获得的知识有助于开发更坚固、更安全的飞机设计，特别是暴露在火灾条件下的部件，使工程师能够为 CFRP 结构建立更精确的安全系数，从而有可能防止灾难性故障，进而提高飞机的整体安全性。

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引用次数: 0

Post-fire residual mechanical properties of Q460GJ steel under different pre-tensile stresses 不同预拉伸应力下 Q460GJ 钢的火烧后残余力学性能

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-30 DOI: 10.1016/j.firesaf.2024.104280

Previous studies on the post-fire mechanical properties of steel were conducted with unstressed state, without considering the influence of pre-stress which subjected to structures in reality. In this article, the post-fire residual mechanical properties of Q460GJ steel under different pre-tensile stresses were studied. The stress-strain curve, elastic modulus, yield strength, ultimate strength and fracture elongation of Q460GJ steel after different elevated temperatures heating are analyzed in detail. The experimental results are compared with that of Q460 steel and S460 steel in the existing literatures. At last, the predictive equations of post-fire mechanical properties of Q460GJ steel under different pre-tensile stresses are established. Q460GJ steel still maintains good ductility after elevated temperature heating, which increases the possibility of reuse of Q460GJ steel element after fire. The Q460GJ steel has better post-fire ductility than that of Q460 and S460 steels. The predictive equations for the post-fire residual mechanical properties for Q460GJ steel under different pre-tensile stresses were proposed. The variation coefficients of yield strength for Q460GJ steel under different pre-tensile stresses after 20 min different elevated temperatures heating were within 0.065. The findings should have a great significance to providing theoretical support for design of reusing or restoring steel building after fire.

以往关于钢材火烧后力学性能的研究都是在无应力状态下进行的，没有考虑实际结构所受预应力的影响。本文研究了 Q460GJ 钢在不同预拉伸应力下的火烧后残余力学性能。详细分析了 Q460GJ 钢在不同升温加热后的应力-应变曲线、弹性模量、屈服强度、极限强度和断裂伸长率。实验结果与现有文献中 Q460 钢和 S460 钢的实验结果进行了比较。最后，建立了 Q460GJ 钢在不同预拉伸应力下的火后力学性能预测方程。Q460GJ 钢在高温加热后仍能保持良好的延展性，这增加了 Q460GJ 钢构件在火灾后重新使用的可能性。与 Q460 和 S460 钢相比，Q460GJ 钢具有更好的火后延展性。提出了 Q460GJ 钢在不同预拉伸应力下的火后残余力学性能预测方程。Q460GJ 钢在不同预拉应力下，经过 20 分钟不同的高温加热后，屈服强度的变化系数在 0.065 以内。该研究结果对火灾后钢结构建筑的再利用或修复设计提供了理论支持，具有重要意义。

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引用次数: 0

Statistical variation of the burning rate and extinction characteristics of engineered timber products 工程木材产品燃烧率和消光特性的统计变化

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-23 DOI: 10.1016/j.firesaf.2024.104275

Understanding the burning rate (mass loss rate, MLR) of timber products is essential in characterizing the ignition characteristics, fire size, and extinction phenomena experienced by timber. Key parameters for timber, such as self-extinction criteria, are presented throughout literature. These parameters are often determined using bench-scale experiments in relatively low trial quantities (e.g., n = 3). This study investigates the influence of trial quantity on the observed statistical variation in key burning rate metrics for timber products (e.g., peak MLR, MLR at extinction). Experiments were performed using a conical heater to conduct 100 repeat trials at incident heat fluxes of 20 kW/m², 40 kW/m², and 50 kW/m² on 12.7 mm (0.5 in.) thick ACX cross laminated plywood samples. Significant variability was observed in trials conducted at 40 kW/m² due to bimodal behavior where 39% of samples experienced self-extinction and the remaining 61% of samples sustained combustion until burnout (i.e., complete pyrolysis of the material). The MLR at extinction for the trials at 40 kW/m² displayed nearly double the magnitude compared to trials conducted at 20 kW/m² due to the breakdown of the semi-infinite solid condition. The results from this work illustrate the significance of large trial quantities when investigating complex phenomena.

了解木材产品的燃烧速率（质量损失率，MLR）对于确定木材的点火特性、火势大小和熄灭现象至关重要。木材的关键参数（如自灭标准）在文献中均有介绍。这些参数通常是通过试验数量相对较少（例如 n = 3）的台架试验确定的。本研究调查了试验数量对观察到的木材产品关键燃烧率指标（如峰值 MLR、熄灭时 MLR）统计变化的影响。实验使用锥形加热器，在入射热通量分别为 20 kW/m2、40 kW/m2 和 50 kW/m2 的条件下，对 12.7 毫米（0.5 英寸）厚的 ACX 交叉层压胶合板样品进行了 100 次重复试验。在 40 kW/m2 下进行的试验中观察到了明显的变化，这是由于双峰行为造成的，其中 39% 的样品经历了自熄灭，其余 61% 的样品持续燃烧直至烧尽（即材料完全热解）。与在 20 kW/m2 下进行的试验相比，在 40 kW/m2 下进行的试验在熄灭时的 MLR 值几乎增加了一倍，原因是半无限固体条件被打破。这项工作的结果表明，在研究复杂现象时，大量试验具有重要意义。

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引用次数: 0

Performance fire tests on building external walls made of sandwich panels 夹芯板建筑外墙性能防火测试

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-19 DOI: 10.1016/j.firesaf.2024.104273

External walls are part of the construction system where new solutions appear every day. These systems are usually built with new materials that offer greater thermal resistance but with poor fire behaviour. This fire behaviour can be evaluated in large-scale tests, such as the ones prescribed at BS 8414-1, LEPIR II or ISO-13785-1 standards, that consider a typical scenario where the fire outbreaks inside the building and spreads to outside through a window or venting. However, there are situations in which these systems can be affected by external fires, such as forest fires, goods burning next to the external wall, or even sabotage, that are of interest to be evaluated. This paper presents the results of experimental tests for evaluating the behaviour of building external walls made of sandwich panels, of four different insulation materials in the core (mineral wool, polyisocyanurate - PIR, organic polymer and polyurethane - PUR). The tests were carried out according to BS 8414-2 standard, considering the common internal and a new external fire scenario. The external fire scenario was intended to simulate the case of goods or equipment stored next to the wall, outside the building, that catches fire. The walls' performance was checked according to BRE 135 Annex B criteria. In these tests were registered the temperatures in the exposed and unexposed face of the walls and the incident radiant heat flux in the wall surface. The external fire scenario showed that can be more aggressive to the external wall cladding than the internal fire, demonstrating that this condition must be carefully investigated to propose this situation in standards for the future.

外墙是建筑系统的一部分，每天都有新的解决方案出现。这些系统通常使用新型材料建造，这些材料具有更强的耐热性，但防火性能较差。这种防火性能可以在大规模测试中进行评估，例如 BS 8414-1、LEPIR II 或 ISO-13785-1 标准中规定的测试，这些测试考虑的是火灾在建筑物内部爆发并通过窗户或通风口蔓延到外部的典型情况。然而，在某些情况下，这些系统可能会受到外部火灾的影响，例如森林大火、外墙旁边的货物燃烧，甚至是人为破坏，这些都是需要评估的。本文介绍了夹芯板建筑外墙行为评估的实验测试结果，夹芯板中含有四种不同的保温材料（矿棉、聚异氰尿酸盐、有机聚合物和聚氨酯）。测试根据 BS 8414-2 标准进行，考虑了常见的内部和新的外部火灾情况。外部着火情况是为了模拟建筑物外存放在墙壁旁边的货物或设备着火的情况。根据 BRE 135 附件 B 标准对墙体性能进行了检查。在这些测试中，记录了墙壁暴露面和未暴露面的温度以及墙壁表面的入射辐射热流量。外墙着火情况表明，外墙覆层比内墙着火更具侵蚀性，这表明必须对这种情况进行仔细调查，以便在未来的标准中对这种情况提出建议。

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引用次数: 0

On gravity-driven liquid nitrogen jets reach and horizontal spread for extinction of ground fires by aerial means 关于重力驱动液氮喷射器的射程和水平传播，以空中手段扑灭地面火灾

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-19 DOI: 10.1016/j.firesaf.2024.104278

This paper describes experimental and numerical results on the reach and the spread of gravity-driven jets of liquid nitrogen (LN₂) on the ground for applications to fire extinction by aerial means. A series of experiments released LN₂ jets from different elevations in ambient air to measure their reach and spread distances upon the impingement. A numerical model was developed to simulate the behavior of such jets. Upon validation, the numerical model was used to further predict the LN₂ pool mass and spreading distances under various release configurations. Results showed that the LN₂ survivability is greatly affected by the release height of the cryogen, since the LN₂ quantity reaching the ground decreases as the release height increases. Moreover, releasing larger initial LN₂ quantities and, most importantly using larger nozzle diameters, both the LN₂ pool mass and spreading diameter can be extended. Additional experiments were conducted where cryogen jets were released onto small (∼300 cm²) alcohol pool fires; results showed that only limited quantities of the LN₂ evaporated in transit to the fire, and small amounts of the cryogen expediently snuffed the fires. A simplified model also suggested that in fire supression/extinction by LN₂ the fuel cooling mechanism is of secondary importance compared to the mechanism of separating the fuel from oxygen.

本文介绍了应用于空中灭火的液氮（LN2）重力驱动喷射流在地面的到达和传播距离的实验和数值结果。一系列实验从不同高度在环境空气中释放液氮射流，以测量其撞击后的射程和扩散距离。开发了一个数值模型来模拟这种射流的行为。经过验证后，该数值模型被用于进一步预测各种释放配置下的 LN2 池质量和扩散距离。结果表明，由于到达地面的 LN2 量随着释放高度的增加而减少，因此 LN2 的存活率在很大程度上受到低温释放高度的影响。此外，释放更大的初始 LN2 量，最重要的是使用更大的喷嘴直径，可以扩大 LN2 池质量和扩散直径。还进行了其他实验，向小型（∼300 平方厘米）酒精池火灾释放低温喷射物；结果表明，只有有限数量的 LN2 在运往火灾现场的途中蒸发，少量低温物质可迅速扑灭火灾。一个简化模型还表明，在利用 LN2 抑止/扑灭火灾的过程中，燃料冷却机制与燃料与氧气分离机制相比是次要的。

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引用次数: 0

CFD-based analysis of deviations between thermocouple measurements and local gas temperatures during the cooling phase of compartment fires 基于 CFD 的车厢火灾冷却阶段热电偶测量值与局部气体温度之间的偏差分析

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-17 DOI: 10.1016/j.firesaf.2024.104276

Data from thermocouple (TC) measurements play a pivotal role in fire safety science and engineering studies. It is well-known that there are deviations from the actual local gas temperature and many studies have led to the development of correction factors. The present study focuses on these deviations inside compartments through a systematic series of CFD simulations, performed with Fire Dynamics Simulator (FDS), version 6.8.0. A canonical cubic box is used as geometry. This allows for the demonstration of the impact of the presence of smoke, with variable optical thickness, on the TC data as retrieved from FDS. Significant differences are observed between TC measurements and local gas temperatures. Corrections as developed for TC measurements in open atmospheres cannot be readily applied in compartment configurations, where smoke properties change both spatially and temporally.

热电偶 (TC) 测量数据在消防安全科学和工程研究中发挥着举足轻重的作用。众所周知，当地气体温度与实际温度存在偏差，因此许多研究都开发了校正系数。本研究通过使用火灾动力学模拟器（FDS）6.8.0 版进行一系列系统的 CFD 模拟，重点研究隔间内的这些偏差。模拟使用了一个典型的立方体盒子作为几何体。这样就可以证明存在不同光学厚度的烟雾对从 FDS 获取的 TC 数据的影响。TC 测量值与当地气体温度之间存在显著差异。为开放大气中的 TC 测量而开发的校正方法不能轻易应用于隔室配置中，因为烟雾特性在空间和时间上都会发生变化。

引用次数: 0

Experimental investigation into the effect of transparent fireproof coatings on charring behavior of glued laminated timber exposed to fire 透明防火涂料对暴露于火中的胶合层压木材炭化行为影响的实验研究

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-16 DOI: 10.1016/j.firesaf.2024.104274

As timber structures evolve towards greater heights and longer spans for buildings, there is a pressing need to enhance the fire resistance of timber structures. Considering the charring behavior of timber is crucial to the fire resistance of timber structures, it is a promising way to retard the charring behavior of timber and further enhance the fire resistance by applying transparent fireproof coatings. In this study, a series of fire tests were conducted to investigate the effect of transparent fireproof coatings on the charring behavior of Douglas fir glued laminated timber (Glulam) under small-scale ISO 834 standard fire conditions. Different coating types, coating quantities, exposed time to fire and member sizes were considered in the experiments. The experimental results including temperature profiles, maximum temperature, and charring rates for uncoated and coated Glulam specimens were carefully recorded and analyzed. Then, the effect of transparent fireproof coatings was quantified by the proposed ratio of delayed charring. The main mechanism of the delayed charring in fire was finally discussed. This study demonstrated that two transparent fireproof coatings can both effectively lower the temperature at different depths and delay the charring behavior of timber. The reduction in charring rates increased with the increase of coating quantity and decreased as the fire exposure time progressed. The ratio of delayed charring for two coatings can be over 30 % in the initial stage of fire and over 20 % for 1-h standard fire exposure. This study can provide technical support for enhancing the fire resistance of timber structures using transparent coatings.

随着木结构建筑向更高更长的方向发展，迫切需要提高木结构的耐火性。考虑到木材的炭化行为对木结构的耐火性至关重要，因此通过涂抹透明防火涂料来延缓木材的炭化行为并进一步提高其耐火性是一种很有前景的方法。本研究进行了一系列火灾试验，以研究在 ISO 834 标准的小规模火灾条件下，透明防火涂料对花旗松胶合层压材（胶合木）炭化行为的影响。实验中考虑了不同的涂层类型、涂层数量、暴露在火中的时间和构件尺寸。实验结果包括未涂覆和涂覆胶合木试样的温度曲线、最高温度和炭化率，并进行了仔细记录和分析。然后，通过提出的延迟炭化比率量化了透明防火涂层的效果。最后讨论了火灾中延迟炭化的主要机理。这项研究表明，两种透明防火涂料都能有效降低不同深度的温度，延迟木材的炭化行为。随着涂料用量的增加，炭化率的降低幅度增大，而随着火灾暴露时间的延长，炭化率的降低幅度减小。在火灾初期阶段，两种涂料的延迟炭化率可达 30% 以上，在标准火灾暴露 1 小时后，延迟炭化率可达 20% 以上。这项研究可为使用透明涂料提高木结构的耐火性提供技术支持。

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引用次数: 0

Effect of nano-aluminum hydroxide on the liquid phase properties and fire-fighting foam performance of the mixed surfactants solution 纳米氢氧化铝对混合表面活性剂溶液液相性质和灭火泡沫性能的影响

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-16 DOI: 10.1016/j.firesaf.2024.104277

Short-chain fluorocarbon surfactants show synergistic effects with hydrocarbon surfactants in foaming and foam stability. Nano-aluminum hydroxide (nano-ATH) was added as an additive to the short-chain fluorocarbon surfactant mixture solution, which was found to increase the surface tension and viscosity of the surfactant mixture solution, and decrease the foaming properties of the solution, as measured by Wilhelmy method, Waring Blender method and viscometer. By measuring zeta potential experiments, surfactant molecules were found to be adsorbed on nano-ATH through charge gravity, which increased the desorption energy of nano-ATH. Measuring the visco-elastic modulus of the solution by rheometer, it was found that nano-ATH increased the visco-elastic modulus of the surfactant mixture solution, which improved the foam's resistance to the external disturbances. Observed by the image analysis system on the foam, the uniform distribution of nano-ATH in the liquid film reduced the coarsening and coalescence speed of foam. Through the self-developed oil resistance test, nano-ATH enhanced the oil resistance stability and inhibition of fuel vapor diffusion of the foam by about 12 %; through self-developed foam fire extinguishing and anti-burning tests, nano-ATH shortened the fire extinguishing time of the two-phase foam by 25 %, and showed better fire extinguishing and anti-burning performance than the foam.

短链碳氟化合物表面活性剂与碳氢化合物表面活性剂在发泡和泡沫稳定性方面具有协同作用。在短链碳氟化合物表面活性剂混合溶液中加入纳米氢氧化铝（nano-ATH）作为添加剂，经 Wilhelmy 法、Waring Blender 法和粘度计测定，发现纳米氢氧化铝会增加表面活性剂混合溶液的表面张力和粘度，降低溶液的发泡性能。通过测量 zeta 电位实验发现，表面活性剂分子通过电荷引力吸附在纳米ATH 上，从而增加了纳米ATH 的解吸能。通过流变仪测量溶液的粘弹性模量，发现纳米 ATH 增加了表面活性剂混合溶液的粘弹性模量，提高了泡沫的抗外界干扰能力。通过泡沫图像分析系统观察，纳米 ATH 在液膜中的均匀分布降低了泡沫的粗化和凝聚速度。通过自发耐油试验，纳米-ATH 增强了泡沫的耐油稳定性和抑制燃料蒸汽扩散的能力，提高了约 12%；通过自发泡沫灭火和防燃烧试验，纳米-ATH 使两相泡沫的灭火时间缩短了 25%，灭火和防燃烧性能优于泡沫。

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引用次数: 0

Analysis of spatial and design factors for users' acceptance of rescue rooms in road tunnels: An exploratory study using Virtual Reality 分析用户接受公路隧道救援室的空间和设计因素：利用虚拟现实技术进行探索性研究

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-10 DOI: 10.1016/j.firesaf.2024.104272

In emergency fire situations in road tunnels in which vehicles cannot exit the tunnel, evacuation on foot might be the only alternative. In such scenarios, self-rescue using rescue rooms might provide provisional safe shelter to people trapped in tunnel emergencies. Yet, a stay in a rescue room with unsatisfactory design might contribute to higher levels of distress to the users. The present study examines five different designs of rescue rooms via virtual reality, to study how the different design and spatial factors might affect users' acceptance of such rooms. Thirty-seven people participated in the study, in which both objective (Eye-tracking and heart rate measurement) and subjective data was collected. The results suggest that two factors (i.e. lighting and use of separate areas) increased the feelings of safety and users' acceptance of the rescue rooms. In particular, a container room with blue lighting and separate area for injured people was the favourite among the study participants. The outcomes of this study show that design and spatial factors are crucial if rescue rooms are to be implemented and used in road tunnels.

在公路隧道发生火灾的紧急情况下，车辆无法驶出隧道，步行疏散可能是唯一的选择。在这种情况下，利用救援室进行自救可为被困在隧道紧急情况中的人员提供临时安全庇护所。然而，在设计不尽人意的救援室中逗留可能会给使用者带来更大的痛苦。本研究通过虚拟现实技术研究了五种不同设计的救援室，以探讨不同的设计和空间因素会如何影响用户对救援室的接受程度。37 人参与了这项研究，研究收集了客观数据（眼球跟踪和心率测量）和主观数据。结果表明，两个因素（即照明和独立区域的使用）增加了用户的安全感和对救援室的接受度。其中，带有蓝色照明和伤员独立区域的集装箱室最受研究参与者的青睐。研究结果表明，如果要在公路隧道中实施和使用救援室，设计和空间因素至关重要。

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引用次数: 0

A waypoint based approach to visibility in performance based fire safety design 在基于性能的消防安全设计中采用基于航点的能见度方法

IF 3.4 3区工程技术 Q2 ENGINEERING, CIVIL

Fire Safety Journal

Pub Date : 2024-10-05 DOI: 10.1016/j.firesaf.2024.104269

In performance based fire safety design, ensuring safe egress, e.g. by visibility of safety signs, is a crucial safety goal. Compliance with the building requirements is often demonstrated by simulations of smoke spread. Numerical models like the Fire Dynamics Simulator generally compute visibility as a local quantity using the light extinction coefficient, without the consideration of the actual light path to a safety sign. Here, visibility maps are introduced, providing an approach for post-processing fire simulation data. They indicate safe areas along egress routes, with respect to visibility. At each location, the available visibility is calculated using Jin’s empirical relation, as an integrated value of the extinction coefficient along the line of sight to the closest exit sign. The required visibility results from the distance between those points. Additional parameters like view angle or visual obstructions are considered. The presented method allows for temporal visibility assessment, e.g. in an ASET-RSET analysis.

在基于性能的消防安全设计中，确保安全出口（如安全标志的可见度）是一个重要的安全目标。通常通过模拟烟雾扩散来证明是否符合建筑要求。火灾动力学模拟器等数值模型通常使用光消光系数将能见度作为局部数量进行计算，而不考虑安全标志的实际光路。这里引入了能见度地图，为火灾模拟数据的后期处理提供了一种方法。能见度图根据能见度标示出逃生路线上的安全区域。在每个位置，可用能见度都是通过金的经验关系计算出来的，即沿着最近出口标志的视线的消光系数的综合值。所需的能见度来自这些点之间的距离。此外，还考虑了视角或视觉障碍物等其他参数。所提出的方法可用于时间能见度评估，例如在 ASET-RSET 分析中。

引用次数: 0