Case Studies in Fire Safety

Jet fans are increasingly preferred over traditional ducted systems as a means of ventilating pollutants from large spaces such as car parking buildings. Outside of tunnel applications jet fans are considered to have limitations as means of smoke control. This is because their effectiveness is limited without side walls and they de-stratify the smoke layer. Jet fans can however, aid post-event in smoke clearance under the control of the attending fire brigade. The prudent fire mode strategy in those jurisdictions where jet fans are not used for smoke control is for the ventilation system to shut down on a fire alarm signal. The problem lies in the jet fans receiving that signal. A fire has three basic signatures; heat, smoke, and light. Large car parking buildings may be sprinkler-protected. Sprinklers operate on the heat signature. A jet fan is assumed to disrupt this signature by forcing the plume of heat downstream and diluting that plume with cool air. This may delay sprinkler activation. In terms of the smoke signature, the presence of pollutants such as carbon monoxide that could be detected by a specialised detector, are the same signals that would cause a jet fan to increase its flow in normal mode. The response to a smoke signature is contradictory between the desired normal-mode reaction to speed up and the fire-mode reaction to shut down. This leaves light. Fires are very rich across the non-visible light spectra and flame detectors are an effective way to provide a fire signal independent of the normal-mode operation of the jet fans. However, the cost-benefit of installing flame detectors in addition to sprinklers is questionable. A series of detailed computational analyses are therefore undertaken to quantify the impact of the jet fans on delaying sprinkler activation on a typical car park sprinkler arrangement. This article assumes the perspective of a jurisdiction where the fire mode strategy is for the fans to shut down. However, the sprinkler delay will also be of interest where the fire mode strategy is to continue operating. Once sprinkler activation had occurred a fire signal is assumed to have been generated to shut down the jet fans. Separate evaluations can then be made as to whether the delay was acceptable or not, dependent upon to the specific building geometry. The results indicate that for a fast-growing design fire, sprinkler activation occurred at ∼180 s with the jet fans off and at ∼210 s with them on: an increase of ⩽30 s. A separate analysis was undertaken for the case-specific egress safety margin. Comparing the two, it was concluded, that the impact of jet fans upon sprinkler activation was not significant. It was further established that the smoke disturbance due to the jet fan flow did not adversely affect the visibility for those escaping.

P.A. (Tony) Enright

Impact of jet fan ventilation systems on sprinkler activation

射流风机通风系统对喷淋启动的影响

Fire safety engineering (FSE) has become widely accepted throughout the world. This is quite an accomplishment for a young engineering discipline. Fire safety engineers are employed by public and private sector organizations of all types. We are involved in almost all major building and infrastructure projects, enabling amazing buildings to be designed, constructed and occupied. We play critical roles in high hazard industries, helping to mitigate risks and achieve acceptable levels of safety. We undertake groundbreaking research and develop new technologies aimed at reducing the impacts of unwanted fire. However, as an engineering discipline, we lack several attributes that one might expect to see in a mature discipline, including a robust analytical engineering framework. We have not experienced any transformational changes in technology or practice in some time. FSE degree programs and recognition of FSE as a unique discipline remain lacking in several countries, leading to wide variation in the level and consistency of fire safety performance delivered. This has unfortunately led some to question the competency and the efficacy of the profession, in some cases resulting in more regulatory control over the fire safety engineering analysis and design of buildings. The net result is that we are at a crossroad. We face some significant challenges, but we have the opportunity to shape an amazing future. If we are up to the challenges and take advantage of the opportunities, we have a chance to evolve the discipline towards maturity and greater respect. In this article I outline my view of the current situations, some of the challenges we face, steps we might take to overcome them, and areas for research, development and implementation into practice concepts that can lead to a promising future.

Brian J. Meacham

Fire safety engineering at a crossroad

火灾安全工程的十字路口

This paper considers why some fire safety professionals have become critical of a reliance on pressurization as the dominant form of smoke control in high rise buildings. Design, installation and operational challenges are discussed and alternative solutions presented alongside guidance to building designers and approval authorities.

Simon Lay

Pressurization systems do not work &amp; present a risk to life safety

加压系统失效并危及生命安全

Computational fluid dynamics (CFD) has been employed to reconstruct the burning of solid combustible materials of a house fire in Parkes, New South Wales, Australia. Experiment was conducted in a compartment room containing multiple combustible materials with an identified ignition source. Large scale fire development involving the spread of flame and smoke leading to the untenable condition of flashover was observed from on-site visualisations as well as comparison to calculated heat release rates. Significant transient fire events taken from experimental footages including the spread of flame on furniture such as couch and carpet were captured through the numerical model. The present simulation and experimental studies are currently being utilised as components for online fire training program for fire-fighters.

A.C.Y. Yuen

G.H. Yeoh

R. Alexander

M. Cook

Fire scene reconstruction of a furnished compartment room in a house fire

房屋火灾中配备家具的房间火灾现场重建

This paper contains a proposal of new Swedish framework for performance-based design of road tunnel fire safety derived from Swedish and European regulation. The overall purpose of the guideline is to protect life, health, property, environment, and key societal functions from fire. The guideline is structured into five key groups of requirements: #1 Proper management and organisation, #2 to limit the generation and spread of fire and smoke, #3 to provide means for safe self-evacuation, #4 to provide means and safety for the rescue service, and #5 to ensure load-bearing capacity of the construction. Each group contains a hybrid of prescriptive requirements, performance-based requirements, and acceptable solutions. Prescriptive requirements must be fulfilled, however, it is the choice of the design team to either adopt the proposed acceptable solutions, or to design alternative solutions by verifying that performance-based requirements are satisfied. For verification of performance-based requirements through risk analysis the operational, epistemic, and aleatory uncertainties are considerable. Therefore, a scenario-based risk analysis with several specified input variables and methods is recommended for verification of #3 and #5. Indispensable complements are scenario exercises, emergency exercises and similar methods that validate the design and highlight organisational aspects. The proposed design guide has been developed by the authors together with the advisory group established for the work.

Jonatan Gehandler

Haukur Ingason

Anders Lönnermark

Håkan Frantzich

Michael Strömgren

Performance-based design of road tunnel fire safety: Proposal of new Swedish framework

基于性能的道路隧道消防安全设计：提出新的瑞典框架

Engineers rely on studies that publish building evacuation data from various occupancies when conducting an egress analysis; this usually includes the people's pre-movement and movement times. However, much of the available data was collected in Western cultures, such as the U.S., which brings into question their validity to other non-Western cultures, such as Saudi Arabia. This study examines how cultural differences between the U.S. and Saudi Arabia can affect occupants' self-reported recognition/reaction times, and the cognitive state of occupants during a fire drill. The results of this research indicate that the U.S. populations are more likely to recognize and react to a fire alarm faster than the Saudi populations during a fire drill.

Majed Almejmaj

Jeanine LM Skorinko

The effects of cultural differences between the us and saudi arabia on emergency evacuation—Analysis of self reported recogntion/reaction times and cognitive state

美国与沙特阿拉伯文化差异对紧急疏散的影响——自我报告的认知反应时间和认知状态分析

Gypsum "dehydration" phenomena, occurring when gypsum plasterboard wall assemblies are exposed to a high temperature environment, result in water vapour production and subsequent dispersion in the fire compartment; these phenomena are often neglected in relevant Computational Fluid Dynamics (CFD) simulations. Aiming to investigate the impact of gypsum dehydration in full-scale CFD simulations of lightweight drywall buildings, the FDS code is used to simulate a two-storey residential building, exposed to a typical domestic fire scenario. The building employs a structural steel frame combined with gypsum plasterboard wall assemblies. Temperature-dependent thermo-physical properties are used for all construction materials. The effects of gypsum dehydration are assessed by using two alternative modelling approaches, an effective specific heat model and a solid reaction kinetics model; the obtained predictions are compared to a benchmark test case, where no such phenomena are modelled. The obtained results demonstrate that when the highly endothermic gypsum dehydration phenomena are simulated, lower overall heat release rates, gas and wall surface temperatures are predicted. In addition, the developed solid reaction kinetics model allows, for the first time, quantitative predictions of gypsum dehydration induced water vapour production and dispersion phenomena.

Dionysios I. Kolaitis

Eleni K. Asimakopoulou

Maria A. Founti

Fire behaviour of gypsum plasterboard wall assemblies: CFD simulation of a full-scale residential building

石膏板墙体组件的火灾行为：全尺寸住宅建筑的CFD模拟

Colored powders such as colored corn starch are used in events such as The Color Run to blanket the air and surroundings with decorative color. Their use, however, presents a risk of dust explosion. The fact that such powders are used at events drawing large crowds makes any fire or explosion likely to result in a mass casualty incident. For instance, the Formosa Fun Coast explosion on June 27, 2015, resulted in multiple deaths and injuries. Development of alternatives to flammable/explosive colored powders would eliminate this hazard. We demonstrate as a proof-of-concept that an ultrasonically driven water mist can produce effects similar to those created by colored powders. Food coloring was dissolved in water, and the colored water was subsequently dispersed from various ultrasonic devices and photographed. Colored clouds were formed from the colored water. Colored clouds were visible under various conditions, and color combinations were possible. Possible risks of colored corn starch and water mists are discussed. An ultrasonic misting system is capable of safely replacing colored powders with regard to appearance.

Yi-Chan Chiu

Wan-Ting Hong

Nelson Chen

Ultrasonically dispersed dyed water mists as a substitute for colored powders

超声分散染色水雾作为彩色粉末的替代品

This paper explores the use of multi-agent continuous evacuation modelling for representing large-scale evacuation scenarios at music festivals. A 65,000 people capacity music festival area was simulated using the model Pathfinder. Three evacuation scenarios were developed in order to explore the capabilities of evacuation modelling during such incidents, namely (1) a preventive evacuation of a section of the festival area containing approximately 15,000 people due to a fire breaking out on a ship, (2) an escalating scenario involving the total evacuation of the entire festival area (65,000 people) due to a bomb threat, and (3) a cascading scenario involving the total evacuation of the entire festival area (65,000 people) due to the threat of an explosion caused by a ship engine overheating. This study suggests that the analysis of the people-evacuation time curves produced by evacuation models, coupled with a visual analysis of the simulated evacuation scenarios, allows for the identification of the main factors affecting the evacuation process (e.g., delay times, overcrowding at exits in relation to exit widths, etc.) and potential measures that could improve safety.

E. Ronchi

F. Nieto Uriz

X. Criel

P. Reilly

Modelling large-scale evacuation of music festivals

音乐节大规模疏散建模

This paper uses four different simple geometrical shapes to simulate a large-scale heavy goods vehicle (HGV) tunnel fire experiment using Fire Dynamics Simulator, version 6 (FDS6) in order to investigate the influence of using different fuel package shapes. Simulations also investigate the influence on temperature profiles when a large target is placed downstream of the fuel package. Predictions of flame extension, temperature profiles and gas species concentrations are compared with the experimental data. The use of the geometrical shapes causes significant differences in flame extension lengths during the fully developed fire phase. The variation in temperature predictions caused by using the different fuel shapes are insignificant when a large target is present behind the fire, however this is not the case if the target is omitted especially during the fully developed phase.

Xiaoyun Wang

Charles Fleischmann

Michael Spearpoint

Assessing the influence of fuel geometrical shape on fire dynamics simulator (FDS) predictions for a large-scale heavy goods vehicle tunnel fire experiment

评估燃料几何形状对大型重型货车隧道火灾实验中火灾动力学模拟器（FDS）预测的影响

出版信息	出版商: Elsevier B.V.，出版周期: ，期刊类型: journal，开源期刊: 否
基本数据	创刊年份: 2014，原创研究文献占比: ，自引率:， Gold OA占比:

Case Studies in Fire Safety

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