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An experimental evaluation of the impact of ventilation opening geometry on enclosure fire severityLennon, Patrick January 2002 (has links)
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Educating engineers for a holistic approach to fire safetyWoodrow, Michael January 2013 (has links)
Problems can be solved using existing knowledge and methods derived from past experiences; and in building design, where buildings are sufficiently similar to those already built, this process can be optimised by creating standardised solutions to common problems. There is significant demand for specialist engineers who can apply these standardised solutions to established problems quickly and accurately; but novel designs generate entirely new problems for which established solutions are not always applicable. Generalist engineers working on novel designs must first define the problems before they can develop options and if necessary, create optimised solutions. Fire safety engineering (FSE) is the process of achieving fire safety in our built environment. The field requires both specialists trained in current practice and generalists skilled in creative and critical thinking. Current fire safety engineering education is mostly aimed at producing specialists, yet there is growing demand for generalists in high-end architecture, hindered by a lack of generalist education. Current education literature in FSE explains in detail what to teach, however they do not explain how to motivate students to learn what is taught; how to create the ‘need to know’ - the purpose that drives learning. The purpose can either be intrinsically motivating (i.e. the subject is interesting) or extrinsically motivating (i.e. if you don’t learn it then you will fail the exam). The former is sustained by autonomy and choice; the latter is sustained by control. Control increases the likelihood that the predicted outcome will be realised, but by definition reduces the likelihood of realising any other outcome, including potential innovation.Initially a study was created to test the effects of creating an autonomous learning environment within a traditional lecture-based ‘fundamentals’ course at the University of Edinburgh. This study, along with observations at a range of US universities led to the formation of an overarching theory of education. Ultimately, purpose is the goal students strive to achieve; autonomy creates the opportunity to think and learn independently; and structure provides the constraints that converge students towards an optimised result, supported by sound evidence and reasoning. Thus the key to generalist education was to provide purpose, autonomy and structure (PAS) in that order. The PAS concept was trialled at EPFL (Switzerland) and the participating students, with no prior knowledge of fire engineering, produced work of exceptional quality. In summary, the present study offers an observational validation that Purpose, Autonomy & Structure (PAS) can be used to effectively support the generalist way of thinking and although the examples given in this paper are related to fire safety engineering (due to the need for generalists in that field), the qualitative evidence on which the conclusions are based is not subject-specific, implying that the PAS methodology could be applied to other disciplines.
Performance-based methodology for the fire safe design of insulation materials in energy efficient buildingsHidalgo-Medina, Juan P. January 2015 (has links)
This thesis presents a methodology to determine failure criteria of building insulation materials in the event of a fire that is specific to each typology of insulation material used. This methodology is based on material characterisation and assessment of fire performance of the most common insulation materials used in construction. Current methodologies give a single failure criterion independent of the nature of the material – this can lead to uneven requirements when addressing materials of different characteristics. At present, fire safety codes establish that performance of different materials or assemblies is assumed to be “equivalent” when subject to the same test, where attainment of the unique failure criteria occurs after a required minimum time. Nevertheless, when using extremely different materials this may not be actually the case. Building performance is currently defined in a quantitative way with respect to factors such as energy usage (i.e. global thermal transmittance), element weight (i.e. thickness and mass), space utilisation and cost of application. In the case of fire performance, only a threshold value is required, therefore a quantitative performance assessment is not conducted. As a result, the drivers are those associated with the variables that can be quantified, whereas the thresholds merely need to be met without any alternative for a better performance. This work opens the door to a performance-based-design methodology that takes into account fire performance as an optimisation variable for the building design, to be used with all other quantifiable variables. An added advantage is that the numerical tool required embraces a low level of complexity. As a result, the possibility for any insulation product to achieve quantifiable and acceptable fire safety levels for required energy efficiency targets is established. As a final remark, an application of the performance assessment methodology that introduces fire safety as a quantifiable variable is presented.
Fire engineering in sustainable buildings : an evaluation for the application of performance-based design in Abu DhabiAl Hashmi, Emad January 2016 (has links)
Sustainable Building Design and Engineering is an integrated approach to energy, health, and operational performance. Abu Dhabi, the capital of United Arab Emirates (UAE) is experiencing a phenomenal growth in built environment. In this context, the Abu Dhabi Government has taken initiatives and measures to sustainable building designs development. This research aimed to develop a guideline for the application of performance- based fire-engineering design with sustainable building designs. In addition, it builds a referral information base helping to build sustainable communities, where fire- related fatalities and risks mitigated. Identifying fire safety and sustainability relation, and assessing technical and regulatory challenges with performance-based designs (PBD) in buildings are also part of this study. It also investigated current practices in sustainable building design and fire safety measures applied by Abu Dhabi Civil Defence (ADCD) under the existing construction legislations. The overall results of the study addressed three main areas, namely, sustainability, fire safety, and legality of the construction industry in Abu Dhabi. The data obtained from the case studies, the questionnaire and face-to-face interviews revealed a strong element of misunderstanding regarding the accurate definition of sustainable building design in Abu Dhabi especially among the stakeholders, including the enforcers. This is by pushing towards sustainable design concepts and technologies without taking into consideration the effects on fire safety level from one side and misunderstanding of the local conditions that shape a local definition for building sustainability in Abu Dhabi hot humid climate. Second, the results relating to fire safety measures in Abu Dhabi showed that some factors in the sector of fire safety seemed to affect the accurate application of Performance- Based Design (PBD). These factors were considered as technical and administrative challenges facing the application of PBD and its safety level. Third, the existing local construction legislation and regulations do not support the application of sustainable building design in innovative designs that implementing fire engineering approach. This includes the lack of legislation, disintegration of requirements between building regulators and absence of law enforcement on building owners. The overall findings of this study showed that the application of fire engineering in the innovative sustainable design under the existing construction legislations and culture could have some serious issues to overcome before achieving accepted safety level. In conclusion, there is a common perception that application of sustainable building design can increase fire safety risk. Innovative fire engineering applications compromises on sustainability and vice-versa. A number of similar studies in Abu Dhabi have shown reduction in fire safety on applying performance- based designs. These are challenging issues with the Governments and they are concerned with the local authorities. The building industries in Abu Dhabi need guidelines to find a trade-off between fire safety and sustainability with application of performance based designs.
Assessment of the thermal efficiency, structure and fire resistance of lightweight building systems for optimized designAmundarain, Aitor January 2007 (has links)
The use of lightweight building systems is very controversial as existing knowledge about their performance is limited. Not enough research has been conducted to determine the suitability of these modern construction technologies and there is an ongoing controversy as to whether they are an appropriate replacement to traditional construction techniques. The prime objective of this study is to present a number of methodologies to assess lightweight external walling systems focusing on thermal efficiency, structure and fire performance, which are currently the main driving forces for this industry. Traditionally, these areas have been studied separately but there is a need to integrate them in order to get comprehensive solutions to the way these systems are designed. The drive to achieve improvements in one of these specific areas could potentially result in reduced effectiveness in the others. That is the reason why an integrative approach is recommended. These techniques are meant to be applied in the design phase of building projects so as to provide early quantitative information about the systems analyzed. The methodologies described herein are then applied to real life light steel building solutions. Within this context, two different wall constructions are examined and conclusions made on their relative performance. The study highlights the importance of having analytical and experimental solutions as a framework for further development. Two different approaches have been considered to assess thermal efficiency, structure and fire performance. On the one hand, a prescriptive approach has been employed to establish regulation compliance. On the other hand, a performance based approach is taken to actually understand and explain how these systems work in real life conditions. The outcome is a comprehensive set of tools to assure both industry and other stake holders.
Modelling of ignition and fire in vented enclosuresGraham, Tony Lee January 1998 (has links)
Fire development in a vented enclosure can proceed in an explosive and disastrous manner called flashover. This thesis examines when, why and how flashover occurs and gives the answers in terms of a few determining dimensionless parameters. The mechanism of flashover considered in this thesis is an enhancement of the burning rate because of thermal radiation from a layer of hot smoke, produced in the course of the fire, to the fire bed. A model, which is proposed for the problem, describes the development fro~ the moment of ignition incorporating the traditional two-zone approach. During early fIre development the density and temperature of the lower zone are reasonably assumed to be close to their initial value. Flashover itself is assumed to occur early in the fIre development, within the fuel controlled combustion regime. The model is analysed using the techniques of classical thermal explosion theory. Explicit criteria are found analytically and graphically to determine if the fIre will achieve flashover or not. The temperature-time characteristics of the fIre development are obtained explicitly for the fIrst time. It is shown that the thermal inertia of the compartment walls can have a significant effect upon the development. The effect of geometrically scaling the compartment is considered. Nondimensional analysis makes such study effective and leads to a square root relationship for the temperature/time characteristics of the fire development. The correlation between the model, four prevIOUS models and small scale experiments is examined. Under reasonable assumptions all models are shown to be described by the same mathematical problem. This means that the criterion for flashover and the development characteristics can be used for any of the modified models observed. Results are illustrated for an experimental fire box used in many experiments.
Effect of lining thermal inertia on small-scale compartment fireYau, Tsz Man January 2001 (has links)
The use of small scale facilities in experimental fire research studies is well estabhshed. This thesis concerns the use of small scale facilities to examine principally the influence of thermal inertia of the lining material on ventilated enclosure fire The radiation error of the thermocouple reading was studied using radiation network models. Previous theoretical studies were implemented to provide improved models appropriate to the more complex arrangements considered here. Modeling was used to assess the radiation error of different sizes of thermocouple in the hot layer measuring position for post and pre flashover fires, and the models were compared with experiment. The current range of thermal inertia values for building products is much wider than those used in the regression by which the classical theory of pre-flashover temperature was derived (McCaffery et al. 1981). The range considered here is greater then has previously been considered by systematic experimental testing whilst maintaining all other independent key variables constant. Using of reasonable assumptions, the mass loss rates of non-flashover and flashover conditions were predicted by numerical calculation integrated with a zone model. Successful prediction was also made for published tests where sufficient information was available, and good agreement was found irrespective of flashover, scale or geometry. Two important and necessary assumptions used in the zone model, concerning specifically radiation heat transfer in the flashover condition are: that an average temperature of hot gas and flashover flame may be represented by a single thermocouple measurement; and that the massive increase in production of flanu-nable vapours from the fuel surface during flashover leads to a "cool core" partial scattering or blocking of the incident radiant heat from the flashover flame and hot gas. A computer programme was developed to implement and test recent flashover theory (Graharn et al. 1995). A logarithinic relationship has here been suggested between the thermal inertia parameter ', 8' and thermal inertia value of lining material. That relationship matches the current experimental results and other published data. The occurrence of flashover and the value of hot gas peak or steady temperature can be predicted using the computer programme, based on the published theory.
Examination of the underlying physics in a detailed wildland fire behavior model through field-scale experimentationMueller, Eric Victor January 2017 (has links)
Complex computer models, built on basic physical principles, have the potential to aid in the understanding and prediction of wildland fire behavior. However, there remain significant uncertainties and assumptions in the way such models describe the fire, the vegetation, and the interaction of the two. To understand a model’s capabilities, limitations, and the improvements which are still necessary, comparison of model predictions to experimental measurement is critical. Unfortunately, collecting such measurements is particularly difficult at the large scale over which real wildland fires occur and, as a result, this happens infrequently. To address this, an opportunity was seized to collect a detailed set of measurements of fire behavior in a real forest environment. These measurements are thoroughly analyzed for the description they provide of the fire behavior. They are then used as a benchmark to test the capabilities of a particular complex model to describe such a fire and to highlight the limitations and uncertainties. As a result of this evaluation, a set of recommendations for future research, both in experiments and modeling, are offered, in order provide a coherent strategy for the future which will significantly advance these models.
An exploration of the basis of calculation of 'standards of fire cover' in member states of the European Union and the potential for a rational economic modelDennett, Michael Frederick January 2002 (has links)
This work has investigated the possibility of developing a model, capable of being used to harmonise standards of fire cover within the EU. The model had to take into account social, humanitarian, economic and environmental factors and the built environment in determining an appropriate emergency response by fire brigades to rescues, fires and contamination of land, air and watercourses. The resulting standards had to be socially acceptable and economically defensible. After examining existing standards of fire cover and the means of determining those standards, all current research into standards of fire cover and related issues was reviewed. A study was also undertaken into fire science, the means of predicting frequency of fire and the means of limiting the incidence and size of fires. Economics, as applied to local and national government and as applied to fire safety systems and fire services was explored. From that initial research it was concluded that the fundamental concepts of fire cover had remained unchanged since the restructuring of fire brigades throughout Europe during the late 1940's and had no relevance to the modern built environment. While some aspects of existing policies and some elements of current research were of value, this work has developed new concepts, including. • Functional requirements for common fire and non-fire emergencies. • Entry preparation time based on the criteria, "The time at which fire fighting shall commence." • Limiting fire size in buildings to "As Small As Reasonably Practicable for a Set Duration" for property protection. • Quantifying the term "As Small As Reasonably Practicable". • Defining a Standard Predetermined Attendance (SPDA) for all incidents. • Determining optimum attendance time limits dependent on the frequency of calls and the installed fire protection features in buildings. • A method of calculating an economic base for determining critical call numbers. • A means of establishing the optimum location of fire stations within a given area. • The number of SPDA's required at each fire station related to total workload. • The provision of assistance to areas that are outside maximum attendance times. The economic model that has resulted, accurately includes all of the potential economic, social, and political variations as the basis of calculation of Standards of Fire Cover in individual Member States of the European Union. It is the contention of this thesis that it is possible to construct formulae, based on sound economic principals, which are capable of being applied to the different fiscal situation in different countries, thereby ensuring similar relative standards.
Two-phase flows accompanying fires in enclosuresKenyon, Yvonne Michelle January 2003 (has links)
The dispersed phase that accompanies enclosure fires, for example, soot, ash, sprinkler droplets and extinguishing powder, could exert a significant influence on the dynamics of the background fluid. In this thesis, the results of a numerical study into the effects of this dispersed phase on the flow in a fire compartment are presented. A two-dimensional computational fluid dynamics solver, with appropriate approximations for low Mach number flows and mathematical sub-models for twophase flows, has been developed in order to simulate fire induced convective motions in planar compartments. The description of the dispersed particulate is based on a twocontinuum approach, whereby the dispersed phase and the gaseous phase are assumed to be two mutually interacting and penetrating continua. In this thesis, two 'passive' models and an 'active' model of the dispersed phase are considered. In the passive models the particulate acts as a tracer only and has no hydrodynamical influence on the gas phase. The second passive model differs from the first in that the production of gases in the fire compartment, for example arising from combustion or propellant gases due to extinguishment of the fire, is taken into account. This second passive model more accurately predicts the growth of pressure in a sealed fire compartment for weak fires. As the volume fraction of the particulate increases the spatial-temporal hydrodynamic influence exerted on the gaseous flow by the dispersed phase becomes significant and, under certain conditions, a passive representation is insufficient. An active onetemperature and one-velocity model is proposed which is appropriate for the description of a hydrodynamically active particulate with an instantaneous velocity and thermal relaxation time. In this thesis, computational fluid dynamics is used as a tool in order to characterise the applicability of the passive models and the active model. The ability of the passive models to accurately predict the growth of pressure in a compartment for 'surface' fires, for example smouldering combustion and weak fires, is investigated. The active model is used to study the hydrodynamics of powder extinguishing media in a compartment with an open doorway.
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