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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

UT Fire, a preprocessor for SAFIR2007, for analysis of heat transfer for structural members exposed to fire

Jennings, Timothy Mark 24 August 2010 (has links)
This thesis describes the development of the computer program UT Fire, which serves as a preprocessor for the computer program SAFIR2007. SAFIR2007, developed at the University of Liege in Belgium, conducts heat transfer analysis and structural response analysis for structures subjected to fire. The preprocessor UT Fire was developed to allow a simplified graphical interface for input to the heat transfer portion of SAFIR 2007. This thesis provides step by step instructions on the use of UT Fire and illustrates its use through a series of detailed examples. / text
2

Computer simulation of hollowcore concrete flooring systems exposed to fire

Chang, Jeremy John January 2007 (has links)
Multi-storey buildings with precast hollowcore concrete floor systems are very common in New Zealand and in many other countries, but the structural behaviour of such systems under fire exposure is not easy to predict because of the complex geometry, composite construction, and a wide range of possible support conditions. The 2006 version of the New Zealand Concrete Standard NZS3101 introduces new details for connection of hollowcore floor units to reinforced concrete supporting beams to improve seismic performance, but the fire performance of the new connection systems is unknown. Currently available methods for simulating fire performance of hollowcore slabs are not suitable for design purposes. Therefore, a simple yet sufficiently accurate simulation method needs to be developed. This study was carried out using a proposed simulation method to investigate the fire performance of hollowcore floor slabs with different connection details between the hollowcore units and their reinforced concrete supporting beams conforming to NZS3101. The proposed simulation method is examined on the platform of SAFIR, a non-linear finite element program that includes both thermal and structural analysis. The proposed simulation method was validated using available experimental results from a limited number of tests. It does not take account of shear and anchorage failures or spalling effects, so designers should consult other studies for this behaviour of hollowcore concrete flooring systems. By using the proposed simulation scheme in SAFIR, it is investigated whether the tensile membrane action established through beams parallel to the hollowcore units and different floor aspect ratios will enhance the fire resistance of hollowcore concrete flooring systems. From the simulation results it is concluded that rigid connections at both the ends and the sides of the hollowcore flooring systems to the supporting beams provide better fire resistance than rotationally flexible connections, and the fire resistance of hollowcore flooring systems can be increased by using stiffer supporting beams at the end of the slabs and also by decreasing the spacing between the beams parallel to the hollowcore units.
3

Branddimensionering av betongpelare enligtEurokod : Jämförelsestudie mellan Zonmetoden ochTabellmetoden

Händig, Andreas, Fridlund, Johannes January 2020 (has links)
One of the biggest challenges of our time is the climate change. With a rapid change infocus for a more substantiality in structural design. This means that we need to reducethis sector emissions and we have with this paper shown how one way of this ispossible. And that is to reduce the amount of concrete in the structure withoutcompromising security or the structural integrity.This report shows that if constructors wants, there is ways to make this happen alreadytoday without making changes in the law or regulations. If building constructers use thezone method, they can reduce the use of concrete with more than 36% concrete pillarshowed by this report.We have trough this paper discovered the main obstacle with calculations and use of thezone method is the temperature and unclarity with the method in the Eurocodes. Wewant to highlight the opportunity’s this method gives constructors to make moreenvironmental choices.
4

Brandpåverkan på samverkanskonstruktion : En utvärdering av betongfylld stålprofil

Andersson, Marcus, Lundberg, Michael January 2014 (has links)
En samverkanspelare drar nytta av interaktionen mellan det omslutande stålröret och profilens betongkärna för att därav erhålla en ökad lastkapacitet. För att förstå beteendet och effekterna av interaktionen mellan stål och betong är det viktigt att förstå de enskilda materialens beteende. Betongens huvudsakliga uppgift i en samverkanspelare är att ta upp tryckkrafter medan stålets främsta uppgift är att motverka momentpåkänning och uppta dragkrafter. I normal rumstemperatur samverkar stål och betong för att bära den aktuella lasten. Samverkanspelaren har stor potential med avseende på lastkapacitet. Nedan tas några av de förväntade positiva effekterna av interaktionen mellan stål och betong upp: Förekomsten av buckling för stålet försenas samtidigt som den försämrade bärförmågan efter lokal buckling uppstått dämpas, beroende på betongkärnans återhållande effekt. Förhindrar spjälkning och hållfasthetsnedsättningen för betongen blir inte lika drastisk. Ökad tryckhållfasthet och deformations kapacitet, speciellt för grövre tvärsnitt. Vid ett brandscenario utsätts pelaren för en temperaturhöjning. Värmeöverföringen från brandgaserna till pelaren sker främst genom strålnings- och konvektionsvärme. Lastkapaciteten för pelarens ingående material kommer att reduceras till följd av denna värmeökning. Storleken för reduceringen beror på hur hög temperatur materialen utsätts för, där en högre temperatur medför en kraftigare reducering. För den betongfyllda stålprofilen kommer således det omkringliggande stålet att fort bli mycket varmt medan betongkärnan erhåller en trögare temperaturökning. I brandfallets initialskede expanderar stålet hastigare än betongen, vilket medför att stålet då i princip bär hela den aktuella lasten. Efter en tid förmår inte stålet längre att vara lastbärare och betongkärnan bär då istället lasten. Pelarens slutliga kollaps sker först då betongkärnan slutligen inte förmår belastningen. En jämförande teoretisk undersökning av samverkans-, betong- och stålpelare under termisk påverkan genomfördes i detta arbete. Beräkningsgången följer de dimensioneringsregler som finns för respektive material i Eurocodes. Kapacitetsberäkningar är gjorda för både normal rumstemperatur likväl som för brandutsatthet. För analys och bestämning av pelartvärsnittens temperaturprofil vid de olika tidsstegen 30, 60 och 90 minuter användes ett nominellt brandförlopp. Tvärsnittens temperaturhistoria användes sedan för att reducera de mekaniska egenskaperna som funktion av temperaturen.Undersökningen konstaterade att samverkans- och betongpelarens kapacitet vid 60 minuters brandpåverkan var tillräcklig. Hand- och datorberäkningar påvisade nästintill likvärdig lastkapacitet vid termisk påverkan och normaltemperatur. / A concrete-filled steel column is taking advantage of the interaction between the enclosing steel profile and the concrete core to obtain an increased load capacity. In order to understand the behavior and effects of the interaction between steel and concrete, it is important to first understand the individual material behavior. The main task of the concrete in a composite column is to absorb pressure forces while the steel's main task is to counteract stress and the tensile forces. At normal room temperature both steel and concrete interact to carry the current load. Concrete-filled steel column has a great potential according to load capacity. Some of the expected positive effects of the interaction between steel and concrete are: The occurrence of buckling for the steel is delayed and the strength deterioration after the local buckling is moderate, both due to the restraining effect of concrete. Prevents the concrete spalling and strength reduction of concrete core will not be as drastic. Increased compressive strength and deformation capacity, especially for large-diameter cross-section. In a fire scenario the column is exposed to a temperature increase. Heat transfer from the combustion gases to the column occurs mainly through radiation and convection heat. The load carrying capacity of the included materials will be reduced as a result of this heat transfer. The size of the reduction depends on how high temperature the materials are exposed to, where a higher temperature leads to a greater reduction. For the concrete-filled steel column, the surrounding steel profile will quickly become very hot while the concrete core obtains a slower rise in temperature. In the initial stage of the fire case the steel expands faster than the concrete, causing the steel to then basically carry the entire load of the column. After some time the steel will be incapable of carrying the load, then instead the concrete core will be the main load carrier. The final collapse of the column occurs only when the concrete core finally will be incapable to carry the load. A comparative theoretical study of concrete-filled steel column, concrete- and steel columns under thermal effects was carried out in this work. The calculation method followed the design rules that exist for each material in the Eurocode. Column capacity calculations are made for both normal room temperatures as well as for fire exposure. The ISO-standard fire curve was used for analysis and determination of each column cross-section temperature profile at the different time stages 30, 60 and 90 minutes. The mechanical properties were then reduced as a function of the temperature. The survey found that the composite and concrete column load capacity exposed to 60 minutes of the ISO-standard fire curve was adequate. Calculations made by hand and with computer showed almost equivalent load capacity by thermal effects and normal temperature.
5

Salvinorin A: Fragment Synthesis and Modeling Studies

McGovern, Donna 23 April 2009 (has links)
Salvinorin A is a non-nitrogenous, selective kappa opioid receptor agonist with potent hallucinogenic properties. Because Salvinorin A has no basic nitrogen, it does not readily adhere to the “message-address” concept of selectivity for the opioid receptors. Therefore, a better understanding of how salvinorin A and its analogs interact with the kappa opioid receptor may shed some light on how salvinorin A obtains its potency and selectivity. The structure-affinity relationships (SAFIR) of salvinorin A and its analogs along with a discussion of the selectivity of the opioid receptors, is presented. A fragment of salvinorin A, methyl-3-acetoxy-4-oxocyclohexanecarboxylate, was synthesized to determine if the B, C and D rings are or are not necessary for binding to the opioid receptors. The fragment was found not to bind to the kappa, delta or mu receptor which reinforces the importance of the B, C and D rings in the binding of salvinorin A to the kappa opioid receptor. Homology models of the kappa, delta and mu opioid receptors were constructed based on inactive bovine rhodopsin, light-activated bovine rhodopsin and the human beta-2 adrenergic receptors. The program MODELLER was also used to construct the kappa opioid receptor. Two comparative molecular field analysis (CoMFA) studies are then presented which compared three different types of alignment methods. The alignment methods employed included a receptor-docked alignment in which the salvinorin A analogs were docked into a model of the kappa opioid receptor using the program GOLD. The docked poses for this alignment were chosen based on their similarity to our postulated model of salvinorin A in the kappa opioid receptor. In our model the furan oxygen forms hydrogen bonds with Q115(2.60) and Y320(7.43), the methoxy oxygen of the C-4 position ester group may form a hydrogen bond with Y312(7.35) and the methyl group of the C-2 position acetoxy moiety forms a hydrophobic interaction with Y313(7.36). These interactions are consistent with mutagenesis studies. The other alignment methods employed were a FlexS alignment and a realignment of the receptor-docked poses using the Fit Atoms function within SYBYL. Only the receptor-docked alignment method resulted in robust and predictive CoMFA models which indicates that the analogs may bind to the kappa opioid receptor in a similar but non-identical way. In addition, information from the CoMFA models based on the receptor-docked alignment led to a postulated binding mode for a set of amine analogs of salvinorin A which were not part of the original data set. Docking studies have the positively charged C-2 position amine group interacting with E209(XL2.49) while the furan oxygen and C-4 position ester group interacts with the same residues as in our model of salvinorin A in the kappa opioid receptor. The studies presented here not only support our postulated model of salvinorin A binding to the kappa opioid receptor but may also explain the trend of the beta epimers of the amine analogs to have a higher affinity than the corresponding alpha epimers. Site-directed mutagenesis studies could provide data to support or refute the postulated models of the amines docked in the kappa opioid receptor presented here.
6

Multi-hazard analysis of steel structures subjected to fire following earthquake

Covi, Patrick 30 July 2021 (has links)
Fires following earthquake (FFE) have historically produced enormous post-earthquake damage and losses in terms of lives, buildings and economic costs, like the San Francisco earthquake (1906), the Kobe earthquake (1995), the Turkey earthquake (2011), the Tohoku earthquake (2011) and the Christchurch earthquakes (2011). The structural fire performance can worsen significantly because the fire acts on a structure damaged by the seismic event. On these premises, the purpose of this work is the investigation of the experimental and numerical response of structural and non-structural components of steel structures subjected to fire following earthquake (FFE) to increase the knowledge and provide a robust framework for hybrid fire testing and hybrid fire following earthquake testing. A partitioned algorithm to test a real case study with substructuring techniques was developed. The framework is developed in MATLAB and it is also based on the implementation of nonlinear finite elements to model the effects of earthquake forces and post-earthquake effects such as fire and thermal loads on structures. These elements should be able to capture geometrical and mechanical non-linearities to deal with large displacements. Two numerical validation procedures of the partitioned algorithm simulating two virtual hybrid fire testing and one virtual hybrid seismic testing were carried out. Two sets of experimental tests in two different laboratories were performed to provide valuable data for the calibration and comparison of numerical finite element case studies reproducing the conditions used in the tests. Another goal of this thesis is to develop a fire following earthquake numerical framework based on a modified version of the OpenSees software and several scripts developed in MATLAB to perform probabilistic analyses of structures subjected to FFE. A new material class, namely SteelFFEThermal, was implemented to simulate the steel behaviour subjected to FFE events.
7

Analysis of the fire resistance of traditional timber flooring systems in historic buildings

García Castillo, Ester 30 July 2025 (has links)
[ES] Los edificios históricos tienen un gran valor arquitectónico y cultural y son un bien muy preciado de nuestra civilización. Por ello, no es de extrañar que se hagan grandes esfuerzos para conservarlos. Sin embargo, a pesar de los avances en la investigación, el fuego sigue siendo una amenaza importante para lograr la conservación del patrimonio construido. Además, los códigos de incendios actuales no suelen proporcionar directrices o métodos específicos que tengan en cuenta las características únicas de los edificios históricos. En consecuencia, conseguir que estos edificios cumplan la normativa de seguridad contra incendios evitando al mismo tiempo la pérdida de patrimonio supone un gran reto. En este contexto, la presente tesis doctoral se centra en el análisis de la resistencia frente al fuego de los forjados de viguetas de madera y revoltones de ladrillos, que pueden encontrarse en muchos edificios históricos de todo el mundo, utilizando enfoques deterministas y probabilistas basados en el rendimiento. Además, la tesis propone modelos probabilísticos para caracterizar las propiedades físicas y mecánicas de la madera contemporánea e histórica a temperatura ambiente y a temperaturas elevadas, que se adoptan en dichos enfoques probabilistas. Debido a la singular geometría y configuración estructural de estos forjados históricos, los métodos establecidos por los códigos de incendios actuales para verificar su resistencia frente al fuego no son aplicables. Por ello, se propone una nueva metodología basada en el "Método de la sección reducida" de la actual EN 1995-1-2. A continuación, la metodología se aplica a un amplio número de forjados que abarcan diferentes luces, resistencias a flexión de la madera y exposiciones al fuego para evaluar la influencia de estos parámetros en la resistencia frente al fuego. Posteriormente, debido al considerable número de parámetros de entrada con una alta incertidumbre que influyen en la resistencia frente al fuego de los forjados de viguetas de madera y revoltones de ladrillos, se adopta un enfoque probabilístico. El análisis asume diferentes secciones transversales y luces para los forjados históricos, así como múltiples geometrías del sector de incendio. Además, considera la incertidumbre de las cargas permanentes y variables aplicadas, así como de las propiedades físicas y mecánicas de la madera a temperatura ambiente y a altas temperaturas. De este modo, en base a un gran número de simulaciones numéricas, se desarrollan curvas de fragilidad y se obtienen los índices de fiabilidad de los forjados históricos frente al fuego. Los resultados muestran que, aunque los enfoques probabilísticos pueden ayudar a preservar un número significativamente mayor de forjados históricos de viguetas de madera y revoltones de ladrillos, muchos de ellos pueden no cumplir los requisitos de resistencia frente al fuego establecidos por los códigos actuales, lo que es motivo de preocupación. Por lo tanto, llevar a cabo estos análisis resulta esencial para garantizar su resistencia frente al fuego y tomar medidas en caso necesario. En definitiva, esta tesis doctoral pretende promover la conservación racional de las estructuras históricas de madera y, en consecuencia, del patrimonio construido. Además, se prevé que los modelos deterministas y probabilistas propuestos también permitan el diseño de estructuras de madera más fiables y eficientes. Así, fomentando la rehabilitación frente a la demolición y la nueva construcción e incentivando el uso de la madera en nuevas estructuras, se puede contribuir también a la mejora de la sostenibilidad del sector de la construcción. Por último, se espera que esta tesis sirva para concienciar sobre la alta vulnerabilidad de los edificios históricos frente al fuego y, en última instancia, para fomentar futuras investigaciones encaminadas a la búsqueda de soluciones que permitan cumplir los requisitos de seguridad contra incendios sin comprometer el patrimonio existente. / [CA] Els edificis històrics tenen un gran valor arquitectònic i cultural i són un bé molt preuat de la nostra civilització. Per això, no és d'estranyar que es facen grans esforços per a conservar-los. No obstant això, malgrat els avanços en la investigació, el foc continua sent una amenaça important per a aconseguir la conservació del patrimoni construït. A més, els codis d'incendis actuals no solen proporcionar directrius o mètodes específics que tinguen en compte les característiques úniques dels edificis històrics. En conseqüència, aconseguir que estos edificis complisquen la normativa de seguretat contra incendis evitant al mateix temps la pèrdua de patrimoni suposa un gran repte. En este context, la present tesi doctoral se centra en l'anàlisi de la resistència al foc dels forjats de biguetes de fusta i revoltons de rajoles, que poden trobar-se en molts edificis històrics de tot el món, utilitzant enfocaments deterministes i probabilistes basats en el rendiment. A més, la tesi proposa models probabilístics per a caracteritzar les propietats físiques i mecàniques de la fusta contemporània i històrica a temperatura ambient i a temperatures elevades, que després s'adopten en els enfocaments probabilistes. A causa de la singular geometria i configuració estructural d'estos forjats històrics, els mètodes establits pels codis d'incendis actuals per a verificar la seua resistència al foc no són aplicables. Per això, es proposa una nova metodologia basada en el "Mètode de la secció reduïda" de l'actual EN 1995-1-2. A continuació, la metodologia s'aplica a un ampli nombre de forjats que abasten diferents llums, resistències a flexió de la fusta i exposicions al foc per a avaluar la influència d'estos paràmetres en la resistència al foc. Posteriorment, a causa del considerable nombre de paràmetres d'entrada amb una alta incertesa que influïxen en la resistència al foc dels forjats de biguetes de fusta i revoltons de rajoles, s'adopta un enfocament probabilístic. L'anàlisi assumix diferents seccions transversals i llums per als forjats històrics, així com múltiples geometries del sector d'incendi. A més, considera la incertesa de les càrregues permanents i variables aplicades, així com de les propietats físiques i mecàniques de la fusta a temperatura ambient i a temperatures elevades. D'esta manera, a partir d'un gran nombre de simulacions numèriques, es desenvolupen corbes de fragilitat i s'obtenen els índexs de fiabilitat dels forjats històrics davant del foc. Els resultats mostren que, encara que els enfocaments probabilístics poden ajudar a preservar un nombre significativament major de forjats històrics de biguetes de fusta i revoltons de rajoles, molts d'ells poden no complir els requisits de resistència al foc establits pels codis actuals, la qual cosa és motiu de preocupació. Per tant, dur a terme estes anàlisis resulta essencial per a garantir la seua resistència al foc i prendre mesures en cas necessari. En definitiva, esta tesi doctoral pretén promoure la conservació racional de les estructures històriques de fusta i, en conseqüència, del patrimoni construït. A més, es preveu que els models deterministes i probabilistes proposats també permeten el disseny d'estructures de fusta més fiables i eficients. D'esta manera, fomentant la rehabilitació per sobre de la demolició i la nova construcció i incentivant l'ús de la fusta en noves estructures, es pot contribuir també a la millora de la sostenibilitat del sector de la construcció. Finalment, s'espera que la present tesi doctoral servisca per a conscienciar sobre l'alta vulnerabilitat dels edificis històrics davant del foc i, en última instància, per a fomentar futures investigacions encaminades a la cerca de solucions que permeten complir els requisits de seguretat contra incendis sense comprometre el patrimoni existent. / [EN] Historic buildings hold significant architectural and cultural value and are a precious asset of our civilisation. It is therefore not surprising that great efforts are being made to preserve them. However, despite advances in research, fire remains a major threat to achieve the conservation of the built heritage. In addition, current fire codes generally do not provide specific guidelines or methods that address the unique characteristics of historic buildings. Consequently, bringing these buildings into compliance with fire safety regulations while avoiding heritage loss is a great challenge. In this context, the present doctoral thesis focuses on the analysis of the fire resistance of timber jack arch flooring systems, which can be found in many historic buildings around the world, using deterministic and probabilistic performance-based approaches. Furthermore, the thesis proposes probabilistic models to characterise the physical and mechanical properties of contemporary and historic timber at ambient and elevated temperatures, which are then adopted in such probabilistic approaches. Due to the singular geometry and structural configuration of these historic flooring systems, the methods established by current fire codes to verify their fire resistance are not applicable. Thus, a new methodology based on the "Reduced cross-section method" of the current EN 1995-1-2 is proposed. Then, the methodology is applied to a wide number of flooring systems covering different span lengths, timber bending strengths, and fire exposures to evaluate the influence of these parameters on the fire resistance. Subsequently, due to the considerable number of input parameters with high uncertainty that influence the fire resistance of timber jack arch flooring systems, a probabilistic approach is adopted. The analysis assumes different cross-sections, span lengths and geometries of the compartment where the fire occurs. Moreover, uncertainty in the applied permanent and live loads, as well as in the physical and mechanical properties of timber at ambient and elevated temperatures, is considered. Thus, based on a large number of numerical simulations, fire fragility functions are developed and the reliability indices of the historic flooring systems against fire are derived. The results of the fire resistance analyses show that, although probabilistic approaches can help to preserve significantly more historic timber jack arch flooring systems, many of them may not meet the fire resistance requirements set by current codes, which is a cause for concern. Conducting these analyses is therefore essential to ensure their fire resistance and take action where necessary. In summary, this doctoral thesis aims to promote the rational conservation of historic timber structures and, consequently, of the built heritage. Moreover, it is envisaged that the proposed deterministic and probabilistic models will also enable the design of more reliable and efficient timber structures. Thus, by fostering rehabilitation over demolition and new construction and by encouraging the use of timber in new structures, a more sustainable construction can also be achieved. Finally, the present doctoral thesis is expected to raise awareness of the high vulnerability of historic buildings to fire and, ultimately, encourage future research aimed at finding solutions that allow fire safety requirements to be met without compromising the existing heritage. / García Castillo, E. (2024). Analysis of the fire resistance of traditional timber flooring systems in historic buildings [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/207365

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