Bridges are critical pieces of infrastructure important to public safety and welfare. Fires have the potential to damage bridges and have been responsible for taking many bridges out of service. The hazard fire poses to bridges is a little studied risk unlike more common threats such as impact, scour and earthquake. Information on the rate of occurrence of bridge fires and the mechanisms of structural response of bridges subjected to fire are both vital to policy makers seeking to address the hazard rationally. The investigation presented developed frequency statistics of bridge fire incidents from several sources of vehicle accident and fire statistics. To further investigate the fire hazard a computational model integrating the simulation of large fires and the simulation of bridge superstructure mechanical response was created. The simulation was used to perform a parametric study of fire size and location to investigate the relationship between these parameters and damage tot bridge super-""structure. The statistics investigation resulted in an observed rate of fires due to vehicle accidents of approximately 175 per year. Approximately one of these per year was the result of a tanker truck carrying a flammable liquid leading to extensive superstructure damage. The simulation showed that a tanker fire resulted in permanent damage to the bridge by several measures where as the affects of a bus fire were minimal. The simulations also demonstrated the mechanisms of bridge response; the importance of girder temperature in that response; and the differences in the response to a tanker fire that can lead to collapse. / Ph. D.

Under 60- och 70-talet var tillväxten i Sverige god. Befolkningsmängden ökade och många valde att flytta från landsbygd till större städer för arbete. Omfattande bostadsbrist ledde till att Miljonprogrammetinfördes – en miljon bostäder skulle byggas på väldigt kort tid.  För effektivisering av byggprocessen började prefabricerade byggkomponenter och lättare byggmaterial att användas. Bostäderna värmdes upp med olja eftersom det var en ekonomiskt gynnsam lösning. Oljekrisen inträffade 1973 och energiransonering infördes, energiförluster genom klimatskalet skulle minskas bland annat genom tilläggsisolering och fönsterbyten.  Idag står miljonprogrambostäderna inför omfattande renoveringar eftersom konstruktionerna drabbats av fuktskador, samtidigt som nya krav om energihushållning, värmeisolering och lufttäthet tillkommit sedan uppförandet. Byggreglerna idag ställer krav på att klimatskiljande delar bör ha så god lufttäthet som möjligt, främst ur fuktskadesynpunkt men på lång sikt även ur energi- och miljösynpunkt. God lufttäthet är bra men allt för god lufttäthet kan orsaka problem vid utrymning eftersom höga brandtryck kan genereras av en brand i en lufttät konstruktion. Möjligheten till utrymning från ett lufttätt brandutrymme, genom en inåtgående dörr, kan påverkas eftersom brandtrycket måste övervinnas vid dörröppning. För undersökning av sambandet mellan lufttäthet och brandtryck har en parameteranalys genomförts i datorsimuleringsprogrammet FDS. Simuleringar har validerat tidigare genomförda brandförsök i vilka utrymningsproblematik genom en inåtgående dörr uppstått. Lufttätheten har i parameteranalysen förbättrats, från 0,73 l/sm2till 0,30 l/sm2. Ventilationslösning har även varierats. Resultatet visade att brandtrycket stiger när lufttätheten förbättras och högst brandtryck, 6 100 Pa, uppmättes med lufttäthet 0,30 l/sm2och stängd ventilation. Lägst brandtryck 700 Pa uppmättes med lufttäthet 0,73 l/sm2och öppen ventilation. Maximala dörröppningskrafter enligt Boverkets byggregler är 25 N och 150 N för personer med respektive utan funktionsnedsättning. Byggreglerna säger att dörrar för utrymning generellt ska öppnas utåt men inåtgående dörrar får förkomma i bostäder, hotell och mindre arbetsplatser. Tumregeln säger att en dörr som öppnas med en kraft på 150 N kan övervinna ett mottryck på 150 Pa.   För att lyckas övervinna öppningskrafter genererade av brandtryck mellan 700 Pa och 6 100 Pa måste utrymning ske inom ett fåtal sekunder. Personer som sover, är påverkade av alkohol eller som har ett hindrat rörelsemönster på grund av hög ålder eller funktionsnedsättning, riskerar att påverkas i en utrymningssituation eftersom ett fördröjt utrymningsförlopp resulterar i stigande brandtryck och stigande dörröppningskrafter som måste övervinnas. / During the 60’s and 70’s the population grew steadily in Sweden. Due to industrialization many people made the decision to move from the countryside to the city. This led to a housing shortage and the so called million program was adopted by the Swedish government–one million dwellings had to be built within a short amount of time.  The building process had to be effective, leading to the introduction of prefabricated building components. The dwellings were heated using oil since it was economically favorable at that time. When the oil crisis unfolded in 1973, energy rationing actions were introduced, and the buildings had to be additionally insulated. The million program dwellings are today in need of extensive renovations since the buildings are damaged by damp. There have been considerable changes in the building regulations as well, mainly regarding energy, insulation and airtightness. The building regulations says that a building construction should have as fair airtightness as possible to prevent damage by damp and moisture, as well as to minimize the use of energy and the climatic influence. Fair airtightness is a good thing, but with airtightness being too good there might arise problems when evacuating due to fire, especially if the door opens inward. An airtight construction may cause higher fire pressures which in turn act as an additional opening force needing to be transcended when evacuating. To analyze the correlation between airtightness and fire pressure a parameter analysis has been conducted using the simulation program FDS. Simulations do validate previously conducted fire experiments where difficulties to transcend an inwards opening door emerged. For the parameter analysis the airtightness has been changed, from 0,73 to 0,30 l/sm2. The ventilation figuration has been varied between open and closed. The result demonstrated the fire pressure rising when the airtightness improved. The maximum pressure of 6 100 Pa occurred with a combination of airtightness 0,30 l/sm2and closed ventilation. The lowest fire pressure of 700 Pa occurred when the airtightness was set to 0,73 l/sm2and the ventilation was open. Maximum door opening forces are according to the Swedish building regulations, Boverkets byggregler,25 N and 150 N, depending on whether the door is constructed to be opened by a person with disabilities or not. Door used for evacuation should be opened outwards, but an inward opening door may be used in dwellings, hotels and smaller workplaces. The rule of thumb says that an operating opening force of 150 N can transcend a back pressure of 150 Pa.  To be able to transcend a door effected by fire pressure between 700 Pa and 6 100 Pa, whilst using the regulated opening forces, evacuation must be carried out within seconds. People being asleep, intoxicated or experiencing difficulties moving due to old age or disability, risk being affected by fire pressure in the sense of a delayed evacuation resulting in higher fire pressures, thus implying greater openings forces.

Ce travail est consacré à l’étude des interactions entre dispositifs de désenfumage naturel et systèmes d’extinction (sprinkleur). Deux campagnes expérimentales à grande échelle utilisant conjointement sprinkleur et désenfumage naturel ont été menées dans des halls d’essais du CNPP. Au total, 98 essais instrumentés ont été réalisés en faisant varier le type et la position du foyer et les temps d’activation respectifs des deux dispositifs de sécurité. Les données recueillies incluent principalement des hauteurs libres de fumées, des champs de température et des temps de déclenchement automatique des sprinkleurs. L’ensemble de ces résultats permet la constitution d’une base de données pour la création de cas de validation en utilisant le logiciel FDS (Fire Dynamics Simulator). Des simulations utilisant les données d’entrée relatives aux différents essais sont réalisées et les résultats numériques sont confrontés aux mesures. Le bon accord entre ces résultats permet d’utiliser FDS pour effectuer des bilans de masse et d’énergie pour les différents scénarios étudiés. En utilisant les connaissances accumulées au cours de ces campagnes, des simulations de scénarios incendie dans deux bâtiments existants ont été réalisées. Pour chaque géométrie, différents temps de déclenchement du désenfumage sont testés et les résultats (niveaux de température, temps et nombre de déclenchements de sprinkleurs, transfert de chaleur et de masse) sont comparés / This work is devoted to the study of interactions between smoke and heat exhaust ventilation systems (SHEAVS) and automatic fire sprinklers. Two real scales experimentation campaigns involving sprinklers and SHEAVS have been carried out in fire test facilities at CNPP (France). A total of 98 instrumented tests have been conducted with various fuel type, experimental configuration and activation time of both systems. Collected datas include smoke free layer height, temperature field and automatic sprinkler activation time. These results are used to build a database in order to create a validation case for the software Fire Dynamics Simulator (FDS). Numerical simulations of several tests are conducted using experimental data as input parameters. Results are then confronted to measurements. A good agreement between these results allows us to use FDS in order to realize mass and energy balances for various scenarios. Using knowledge acquired during both campaigns, numerical simulations of fire scenarios in two actual facilities have been conducted. For both configuration, various SHEAVS activation time have been tested and results (temperature levels, time and number of activated sprinklers, heat and mass transfer) have been confronted

Ziel der Arbeit war die systematische theoretische Behandlung von Gemischen aus bosonischen und fermionischen Atomen in einem Parameterbereich, der sich zur Beschreibung von aktuellen Experimenten mit ultra-kalten atomaren Gasen eignet.<br /> <br /> Zuerst wurde der Formalismus der Quantenfeldtheorie auf homogene, atomare Boson-Fermion Gemische erweitert, um grundlegende Größen wie Quasiteilchenspektren, die Grundzustandsenergie und daraus abgeleitete Größen über die Molekularfeldtheorie hinaus zu berechnen.<br /> <br /> Unter Zuhilfenahme der dieser Resultate System wurde ein Boson-Fermion Gemisch in einem Fallenpotential im Rahmen der Dichtefunktionaltheorie beschrieben. Daraus konnten die Dichteprofile ermittelt werden und es ließen sich drei Bereiche im Phasendiagramm identifizieren: <br /> (i) ein Bereich eines stabilen Gemisches,<br /> (ii) ein Bereich, in dem die Spezies entmischt sind und <br /> (iii) ein Bereich, in dem das System kollabiert.<br /> <br /> Im letzten dieser drei Fällen waren Austausch--Korrelationseffekte signifikant. Weiterhin wurde die Änderung der kritischen Temperatur der Bose-Einstein-Kondensation aufgrund der Boson-Fermion-Wechselwirkung berechnet. Verursacht wird dieser Effekt von Dichtumverteilungen aufgrund der Wechselwirkung.<br /> <br /> Dann wurden Boson-Fermion Gemische in optischen Gittern betrachtet. Ein Stabilitätskriterium gegen Phasenentmischung wurde gefunden und es ließen sich Bedingungen für einen supraflüssig zu Mott-isolations Phasenübergang angeben. Diese wurden sowohl mittels einer Molekularfeldrechnung als auch numerisch im Rahmen eines Gutzwilleransatzes gefunden. Es wurden weiterhin neuartige frustrierte Grundzustände im Fall von sehr großen Gitterstärken gefunden. / The theory of atomic Boson-Fermion mixtures in the dilute limit beyond mean-field is considered in this thesis.<br /> Extending the formalism of quantum field theory we derived expressions for the quasi-particle excitation spectra, the ground state energy, and related quantities for a homogenous system to first order in the dilute gas parameter.<br /> <br /> In the framework of density functional theory we could carry over the previous results to inhomogeneous systems. We then determined to density distributions for various parameter values and identified three different phase regions: <br /> (i) a stable mixed regime, <br /> (ii) a phase separated regime, and <br /> (iii) a collapsed regime. <br /> <br /> We found a significant contribution of exchange-correlation effects in the latter case. Next, we determined the shift of the Bose-Einstein condensation temperature caused by Boson-Fermion interactions in a harmonic trap due to redistribution of the density profiles.<br /> <br /> We then considered Boson-Fermion mixtures in optical lattices. We calculated the criterion for stability against phase separation, identified the Mott-insulating and superfluid regimes both, analytically within a mean-field calculation, and numerically by virtue of a Gutzwiller Ansatz. We also found new frustrated ground states in the limit of very strong lattices. <br><br>----<br>Anmerkung:<br> Der Autor ist Träger des durch die Physikalische Gesellschaft zu Berlin vergebenen Carl-Ramsauer-Preises 2004 für die jeweils beste Dissertation der vier Universitäten Freie Universität Berlin, Humboldt-Universität zu Berlin, Technische Universität Berlin und Universität Potsdam.

In New Zealand, a new method of specific design, Verification Method 2 (C/VM2) has been proposed to be used for fire safety compliance. Previous researchers have investigated different fire parameters and their applications. However, there is a lack of research effort in evacuation calculations and in this research the author uses three different types of evacuation software to calculate the evacuation timings for four different buildings. These buildings include a cinema complex, a four-storey office building, a two-storey restaurant and a sport and recreation complex. Furthermore, this work conducts evacuation analyses to test the applicability of these evacuation tools. Simulex, FDS+Evac and EvacuatioNZ are the evacuation software used and the simulation results are compared with the hydraulic model recommended by C/VM2. Through careful analyses of the escape routes, the hydraulic model can be used to obtain evacuation times in a short timeframe. This calculation can be concise for a simple geometry, but lengthy for complex buildings. However, the hand calculation method has been found to be unsuitable in certain applications, for example buildings with specific seating arrangements, different occupant groups etc. FDS+Evac, in general, generates comparable evacuation times compared to the hydraulic model. As FDS+Evac has a good user interface, one can study the evacuation process easily. However, the computation time for one simulation can be relatively longer than with the other software tools. It was found that this tool is good for complex evacuation situations where a merging or counter-flow situation arises. Simulex, in general, generates faster evacuation times compared to the hydraulic model. Nevertheless, the computation time to complete one run is not too long and the evacuation process can be observed during and after the simulation. Finally, it was discovered that Simulex is not designed for counter-flow evacuation scenarios. EvacuatioNZ generates significantly longer evacuation timings in highly-congested evacuation scenarios, although for single spaces it has comparable results to hydraulic model. Some future work is required before this evacuation tool can be used as a design tool.

Moderna byggnader kan ställa krav på komplicerade brandtekniska lösningar eftersom de kan vara komplexa och inte bestå av konventionella arkitektoniska byggnadsdelar. De stora komplexa byggnaderna kan medföra att brandförhållandena i byggnaden avviker signifikant från de förhållanden som ligger till grund för de traditionella dimensioneringsmetoderna. När dimensionering av komplexa byggnader inte genomförs med traditionella dimensioneringsmetoder, såsom naturliga eller nominella brandförlopp, kan lokal brand eller avancerade brandmodeller användas. Storleken på den lokala branden som används vid dimensionering kan beräknas enligt Eurokod 1 appendix C där appendix E ska användas för att beräkna brandintensiteten. EKS 10 åberopar att appendix E inte får användas utan istället ska brandintensiteten bestämmas genom Boverkets allmänna råd om brandbelastning (BBRBE). Syftet med arbetet var att studera dimensionerande brand vid tillämpning av lokal brand i hyllställningar där brandintensitet, hyllställningens dimensioner och lagringssätt varieras. De temperaturer som uppkommer i brandens centrumlinje var av intresse att undersöka eftersom förhöjda temperaturer kan påverka bärförmågan i bärverket. Målet med arbetet var att tillhandahålla en komplett metod för dimensionerande brand i livsmedelsbutiker. Två metoder tillhandhölls och de utvärderades mot en tredje beräkningsmetod samt mot flödesberäkningskoden FDS för att tydliggöra vilken av de tre handberäkningsmetoderna som var mest lämplig att använda vid beräkning av temperaturer vid lokal brand. Arbetet har utgått från en typisk hyllställning från ett tidigare arbete som har modellerats i FDS. Dimensionerna på den typiska hyllställningen har varierats i arbetet, där fyra olika bredder och höjder har använts. I hyllställningarna har bränslepaket modellerats och ska motsvara en antagen bränslekonfiguration med varierande brandintensitet. Det resulterade i att 36 scenarier simulerades i FDS i 300 sekunder där antändningen var momentan. Från resultaten kunde två nya beräkningsmetoder tillhandahållas, förenklad faktormetod (FFM) och partialkoefficientmetoden (PKM). De två metoderna utvärderades mot den tidigare Ludvigsson-Rydstedts metod (LRM) samt FDS i fallstudier. Fallstudierna genomfördes på tidigare tillhandahållen data samt från en FDS simulering över ett helt brandförlopp från detta arbete. Slutsatser som erhållits utifrån resultaten och de framtagna beräkningsmetoderna är: Av hyllställningens bredd, höjd och brandintensiteten är bredden den parameter som påverkar de beräknade temperaturerna mest vid lokal brand i hyllställning. De temperaturer som uppkommer vid lokal brand i hyllställning påverkas av både brandeffekten från en hyllställning samt brandintensiteten på bränslepaketens ytor. Vid lokal brand i hyllställning kan bärverk påverkas eftersom de uppkomna temperaturerna i några scenarier översteg den kritiska temperaturen för stål. Appendix C i Eurokod 1991-1-2 kan anpassas till brand i hyllställningar om hänsyn tas till brandens startpunkt samt projicerad brandeffekt. 2/3 av hyllställningens höjd är mest lämplig att använda som starthöjd för branden i de framtagna metoderna. Generellt visade metodutvärderingen att LRM gav temperaturer som var konservativa i förhållande till FDS. PKM gav temperaturer som stämde överens med temperaturerna från FDS medan FFM gav något lägre temperaturer jämfört med PKM.

Ce travail est consacré à l'étude des interactions entre combustible, flamme et gouttes d'eau générées par des systèmes de type brouillard d'eau. Il est complété par le développement d'un modèle d'extinction dans le logiciel FDS (Fire Dynamics Simulator), code CFD largement utilisé dans la communauté scientifique et dans l'ingénierie. L'acquisition de connaissances sur les phénomènes physiques induits par l'application d'un spray sur un feu résulte de l'analyse d'une campagne expérimentale à échelle réelle. 84 essais de feux confinés et ventilés ont ainsi été réalisés faisant intervenir un brouillard d'eau et une instrumentation qui permet d'étudier l'influence sur l'extinction: du combustible, du temps de combustion avant déclenchement du brouillard d'eau, du diamètre du bac pour les feux de liquide inflammable, du nombre de buses et du placement du foyer. L'ajout d'un post-traitement au logiciel FDS sous la forme de bilans de masse et d'énergie dans le code permet de compléter les observations expérimentales et de quantifier l'importance des différents transferts thermiques avant et pendant l'aspersion d'eau. Deux modèles complémentaires permettent de déterminer l'extinction par refroidissement du combustible et par refroidissement de la flamme / inertage. Ils sont étudiés pour des cas appropriés sur les versions 5 et 6 de FDS. La capacité du code complet modifié à prédire l'extinction est évaluée / This work is devoted to the study of interactions between fuel, flame and water droplets generated by water mist systems. It is completed by an extinction model development in FDS (Fire Dynamics Simulator) software, which is a CFD code widely used by the scientific and engineering communities. Knowledge on physical phenomena induced by water application on fire is acquired thanks to an experimental campaign at real scale. 84 confined and ventilated fire tests have been carried out involving water mist and metrology allowing to study the influence on extinction of: fuel, combustion time before water mist application, pool diameter for liquid fuel fires, number of nozzles and fuel location. A post-processing in the form of mass and energy balances has been added to FDS, allowing to complete experimental observations and to quantify the different heat transfer modes before and during water application. Two complementary models allow extinction determination by fuel cooling and flame cooling / inerting effects. Their capability is analyzed for appropriate cases on the versions 5 and 6 of FDS. The capability of the complete modified code to predict extinction is finally evaluated

"NIST's Fire Dynamics Simulator (FDS) is a powerful tool for simulating the gas phase fire environment of scenarios involving realistic geometries. If the fire engineer is interested in simulating fire spread processes, FDS provides possible tools involving simulation of the decomposition of the condensed phase: gas burners and simplified pyrolysis models. Continuing to develop understanding of the capability and proper use of FDS related to fire spread will provide the practicing fire engineer with valuable information. In this work three simulations are conducted to evaluate FDS V.4's capabilities for predicting upward flame spread. The FDS predictions are compared with empirical correlations and experimental data for upward flame spread on a 5 m PMMA panel. A simplified flame spread model is also applied to assess the FDS simulation results. Capabilities and limitations of FDS V.4 for upward flame spread predictions are addressed, and recommendations for improvements of FDS and practical use of FDS for fire spread are presented."

In recent year, there were many fire accidents in MRT and subway station,due to faolure in smoke control system and emergency operation strategies. The goal of this project is to use two sofeware¡XFDS and Star-CD to simulate the fire in MRT station and predict the height of smoke layer and its descending rate .The comparison of the two indicated sucessful result can be obtained with deviations within engineering tolerance..

Despite advances in the understanding of fire dynamics over the past decades and despite the advances in computational capacity, our ability to predict the behaviour of fires in general and building fires in particular remains very limited. This thesis proposes and studies a method to use measurements of the real event in order to steer and accelerate fire simulations. This technology aims at providing forecasts of the fire development with a positive lead time, i.e. the forecast of future events is ready before those events take place. A simplified fire spread model is implemented, and sensor data are assimilated into the model in order to estimate the parameters that characterize the spread model and thus recover information lost by approximations. The assimilation process is posed as an inverse problem, which is solved minimizing a non linear cost function that measures the distance between sensor data and the forward model. In order to accelerate the optimization procedure, the ‘tangent linear model’ is implemented, i.e. the forward model is linearized around the initial guess of the governing parameters that are to be estimated, thus approximating the cost function by a quadratic function. The methodology was tested first with a simple two-zone forward model, and then with a coarse grid Computational Fluid Dynamics (CFD) fire model as forward model. Observations for the inverse modelling were generated using a fine grid CFD simulation in order to illustrate the methodology. A test case with observations from a real scale fire test is presented at the end of this document. In the two-zone model approach the spread rate, entrainment coefficient and gas transport time are the governing invariant parameters that are estimated. The parameters could be estimated correctly and the temperature and the height of the hot layer were reproduced satisfactorily. Moreover, the heat release rate and growth rate were estimated correctly with a positive lead time of up to 30 s. The results showed that the simple mass and heat balances and plume correlation of the zone model were enough to satisfactorily forecast the main features of the fire, and that positive lead times are possible. With the CFD forward model the growth rate, fuel mass loss rate and other parameters of a fire were estimated by assimilating measurements from the fire into the model. It was shown that with a field type forward model it is possible to estimate the growth rates of several different spread rates simultaneously. A coarse grid CFD model with very short computation times was used to assimilate measurements and it was shown that spatially resolved forecasts can be obtained in reasonable time, when combined with observations from the fire. The assimilation of observations from a real scale fire test into a coarse grid CFD model showed that the estimation of a fire growth parameter is possible in complicated scenarios in reasonable time, and that the resulting forecasts at localized level present good levels of accuracy. The proposed methodology is still subject to ongoing research. The limited capability of the forward model to represent the true fire has to be addressed with more detail, and the additional information that has to be provided in order to run the simulations has to be investigated. When using a CFD type forward model, additional to the detailed geometry, it is necessary to establish the location of the fire origin and the potential fuel load before starting the assimilation cycle. While the fire origin can be located easily (as a first approximation the location of the highest temperature reading can be used), the fuel load is potentially very variable and its exact distribution might be impractical to continually keep track of. It was however shown that for relatively small compartments the exact fuel distribution is not essential in order to produce an adequate forecast, and the fuel load could for example be established based on a statistical analysis of typical compartment layouts.