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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.
391

Impact des polluants gazeux du sol sur la qualité de l'air intérieur des bâtiments / Impact of soil gas pollutants on indoor air quality

Diallo, Thierno Mamadou Oury 10 October 2013 (has links)
L’entrée des polluants gazeux du sol (Radon, COV,…) dans les environnements intérieurs peut occasionner des risques sanitaires significatifs. Or les modèles d’évaluation de risques sanitaires liés à ces polluants gazeux du sol contiennent beaucoup d’incertitudes qui peuvent conduire à une mauvaise appréciation des risques. Dans un premier temps, cette thèse contribue à l’amélioration des modèles d’évaluation des risques. Dans un second temps, elle propose le développement d’un modèle de dimensionnement des Systèmes de Dépressurisation du Sol (SDS) passifs utilisés pour protéger les bâtiments des pollutions gazeuses venant du sol. L’amélioration des modèles a porté sur la prise en compte des principaux phénomènes de convection et diffusion à l’interface entre le sol et le bâtiment, en tenant compte des différentes typologies de soubassement. La première contribution porte sur le développement de modèles analytiques fournissant les débits d’air dus à la convection à travers le sol pour différents types de soubassement : dallage indépendant, dalle portée, vide sanitaire et cave. Les bâtiments avec des murs enterrés et les soubassements avec un lit de gravier sous le plancher bas sont également traités. Une méthodologie permettant la prise en compte de la fissuration et des points singuliers du plancher bas est aussi proposée. La deuxième contribution porte sur la prise en compte du transfert couplé des polluants des sols par convection et diffusion auprès des fondations. Une étude numérique a permis une meilleure compréhension du comportement des polluants à l’interface sol/bâtiment. Sur la base de cette compréhension, des lois semi-empiriques d’estimation des flux d’entrée de polluant dans les bâtiments sont proposées. Les différents modèles développés ont été validés numériquement avec un modèle CFD et expérimentalement avec des données issues de la littérature. La confrontation de ces modèles avec ceux existants a montré les améliorations apportées. L’impact de la typologie du soubassement sur le transfert de polluants gazeux des sols a été constaté. Une première application des modèles est illustrée par leur intégration dans un code de simulation thermo-aéraulique multizone afin de pouvoir étudier l’impact de ces polluants sur la qualité de l’air intérieur. Ce travail se termine par le développement d’un modèle de dimensionnement des Systèmes de Dépression du Sol (SDS) passifs. Ce modèle aéraulique de dimensionnement des SDS a été validé par des mesures effectuées au CSTB dans une maison expérimentale. Les premières applications du modèle de dimensionnement portent notamment sur l’impact de la météorologie (vent et tirage thermique) sur le fonctionnement du SDS passif et sur l’impact des stratégies de ventilation du bâtiment sur le fonctionnement du SDS passif. On voit ainsi l’intérêt de l’utilisation d’un tel modèle pour tester l’aptitude de ce système de protection des bâtiments dans des situations environnementales données. / Transfer of soil gas pollutants (Radon, VOC) into buildings can cause significant health risks. However, analytical models used today to estimate health risks associated with these pollutants contain many uncertainties which can lead to poor risk assessment. Initially, the main objective of this thesis is to contribute to the improvement of these models for risk assessment. Secondly, we propose the development of air flow model for passive Sub slab Depressurization Systems (SDS) design used to protect buildings. The improvement of models focused on the inclusion of the main phenomena of convection and diffusion at building/soil interface, taking into account different types of building substructures. The first improvement concerns the assessment of convection phenomenon through the development of analytical models to quantify air flow rates entering through many kinds of building substructures: floating slab, bearing slab, crawl space and basement. Buildings with buried walls and substructures with a sub slab gravel layer are also treated. A methodology taking into account the presence of cracks, holes and singular leakages of the slab is also proposed. The second improvement of the models is the inclusion of coupled transfer of convection and diffusion near foundations. A numerical study allowed a better understanding of the behavior of pollutants at soil / building interface. Based on this understanding, semi-empirical laws for estimating soil gas pollutants entry rate into buildings are proposed. The various models developed have been validated numerically using a CFD model and experimentally with data from the literature when available. The impact of building substructure on pollutant transfer has been highlighted. A first application of the model is illustrated by their integration into a multizone simulation code to study the impact of these transfers on indoor air quality. Finally, the work ends with the development of a model for designing passive sub slab depressurization systems. The design model developed is validated with in situ experimental data. Preliminary applications using this model focused at first on the impact of meteorological conditions (stack effect, wind) on the sub slab system running. At second, the impact of ventilation strategies on sub slab depressurization performance is studied. Thus, we see the potential interest of this model to test the effective running of passive sub slab depressurization systems in given configuration.
392

Polymer integrated Young interferometers for label-free biosensing applications

Wang, M. (Meng) 13 November 2012 (has links)
Abstract Integrated optical (IO) sensor allowing sensitive, label-free, real-time and multi-parameter monitoring of bio-molecular interactions are conventionally fabricated with inorganic dielectrics inherited from CMOS manufacturing technology. Polymers as complement materials to inorganic dielectrics are becoming to have an increasing market share for IO circuits in optical communications networks owing to its good optical properties, versatile processibility and low cost. This work aims at developing disposable low-cost biosensors based mainly on polymeric materials, with a performance comparable to inorganic-dielectric based IO biosensors. This thesis describes the development of polymer IO biosensors based on the Young interferometer (YI) transducer platform for ambient noise compensation and a complete periodic intensity fringe pattern. Three different waveguide configurations were utilized, taking into consideration operational simplicity, fabrication simplicity and enhanced sensitivity. Among the developed polymer biosensors, an unconventional interferometer structure: a vertically placed dual-slab waveguide interferometer and an inverted rib waveguide configuration were employed. To enhance the sensitivity of the waveguides, deposition of Ta2O5 high index coating was performed on the rib waveguide configuration. Along with the development of polymer biosensors based on the inverted-rib waveguide configuration, a fabrication process was also developed featuring UV-imprinting and spin coating. The simple two-step fabrication process demonstrated using a polymer mold is potentially transferable to the roll-to-roll manufacture process. Calibration of the developed sensors was performed by homogeneous refractive index (RI) sensing with glucose de-ionized water solutions. By investigating an antibody – antigen binding interaction involving C-reactive protein and its conjugates, this thesis confirmed the applicability of the developed sensors to specific molecule detection. Moreover, to establish the influence of water molecular absorption on measurement stability, an evaluation was carried out on the polymeric waveguide. Finally, the thesis presented a comparison between the developed sensors, exploring their sensitivities, stabilities, limits of detection (LODs) and other aspects related to operation and fabrication. The results indicated that the Ta2O5-coated polymer waveguide sensor had a high sensing capability. In homogeneous RI sensing, the achieved detection limits were 9×10-7 RIU (refractive index unit), i.e., three times the noise level, and 270 fg/mm2 for surface mass density. / Tiivistelmä Integroidulla optiikalla toteutetut anturit mahdollistavat biomolekulaarisen vuorovaikutuksen tutkimisen käyttäen herkkiä moniparametrisia ja merkkiaineettomia menetelmiä. Näiden bioantureiden valmistukseen käytetään tavallisesti CMOS-teknologian piiristä tuttuja epäorgaanisia puolijohteita ja eristemateriaaleja. Viime aikoina on kuitenkin polymeeristen materiaalien käyttöä integroidussa optiikassa tutkittu merkittävästi johtuen polymeerien hyvistä optisista ominaisuuksista, monipuolisesta työstettävyydestä ja edullisista kustannuksista. Tämän työn tarkoituksena on kehittää edullisia, kertakäyttöisiä, pääasiallisesti polymeerisistä materiaaleista valmistettuja bioantureita, jotka vastaavat suorituskyvyltään epäorgaanisista materiaaleista valmistettuja integroidun optiikan antureita. Tässä työssä kehitetyt polymeeriset integroidun optiikan bioanturit perustuvat Youngin interferometriin mahdollistaen ympäristökohinan kompensoinnin ja ne tuottavat pintavuorovaikutusten tutkimiseen jaksoittaisen interferenssikuvion. Työssä hyödynnettiin kolmea erilaista valokanavarakennetta huomioiden niiden käytön helppous, valmistuksen yksinkertaisuus ja mittausherkkyys. Yksi kehitetyistä polymeerisistä bioantureista koostui päällekkäisistä kerrostetuista polymeerikerroksista. Toisen tutkitun rakenteen toiminta puolestaan perustui käänteiseen harjannevalokanavaan. Mittausherkkyyttä parannettiin pinnoittamalla polymeerirakenne Ta2O5-pinnoitteella. Näin muodostui kerrostettu komposiittivalokanava, joka oli tässä työssä tutkittu kolmas sensorirakenne. Itse bioanturien lisäksi kehitettiin myös valmistusprosessi, jossa hyödynnettiin UV-painatusta ja nestefaasipinnoitusta. Tässä työssä havaittiin lisäksi, että kehitetty yksinkertainen valmistusmenetelmä on paitsi toimiva, myös mahdollisesti siirrettävissä rullalta rullalle valmistus- ja tuotantoteknologiaan. Kehitettyjen anturien kalibrointi suoritettiin homogeenisella taitekerroinmittauksella käyttäen liuoksia, jotka valmistettiin glukoosista ja deionisoidusta vedestä. Kehitettyjen anturien soveltuvuus spesifien molekyylien tunnistamista varten todennettiin tutkimalla vasta-aineiden ja antigeenien sitoutumisreaktioita ja vuorovaikutusta C-reaktiivisella proteiinilla ja sen konjugaateilla. Lisäksi työssä tutkittiin veden absorption vaikutusta mittauksen stabiilisuuteen. Tutkimuksessa suoritettiin vertailu kehitettyjen anturien ja niiden ominaisuuksien välillä kiinnittäen huomiota mittausherkkyyteen, stabiilisuuteen, määritys- ja toteamisrajoihin ja muihin anturien valmistukseen sekä käyttöön liittyviin keskeisiin piirteisiin. Tulokset osoittavat, että Ta2O5-pinnoitetun polymeerivalokanavan mittausherkkyys oli suurin vertailluista rakenteista. Homogeenisessä taitekerroinmittauksessa saavutettu määritys- ja toteamisraja oli 9×10-7 taitekerroinyksikköä (RIU). Pintamassatiheysmittauksessa saavuttu tulos oli 270 fg/mm2.
393

Urban regeneration: Urban renewal through eco-systemic design

Cottle, Louis E 03 December 2003 (has links)
The systemic relationship between the human entity and its environment, under the constraint of its function, were used as the perfect example to design and create the systemic relationship of an urban regenerative building with its economical, environmental and social context in the Inner City of Pretoria. / Dissertation (MArch (Prof))--University of Pretoria, 2005. / Architecture / unrestricted
394

Frequency Domain Analysis of Composite Long-Span Cable-Stayed Bridges by Finite Strip Method

Li, Haoran January 2017 (has links)
The finite strip method (FSM) is a very efficient numerical method employed for performing the structural analysis of slender structures, such as cable-stayed bridges; the strip discretization of the model allows for the usage of a lower number of degrees of freedom, in comparison with the finite element method (FEM), while, as it will be discussed in the current research, the results obtained from both methods are in relatively good agreement. Moreover, to address the latest developments in the area of smart construction materials used for long-span bridges, the fiber reinforced polymer (FRP) composites were implemented for the bridge deck modeling, as part of a hybrid composite FRP cable-stayed bridge, and an extend laminate integrated finite strip method (LFSM) was applied for estimating the static structural performance of the hybrid composite FRP long-span cable-stayed bridge under several concentrated and uniformly distributed loadings. The free vibrations analysis was conducted for the Kap Shui Mun Cable-stayed Bridge model, and the natural frequencies were compared with the ones obtained from an FE model of the same bridge. One of the advantages of using the integrated finite strip method is that number of vibration modes, which can be included in the dynamic analysis when the effect of a sweeping sinus and a seismic loading are investigated when a conventional FE analysis would fail to converge. The outcomes of this research will set the stage for the hybrid long-span cable-stayed bridges modeling by the laminate integrated finite strip method (LFSM) which is more efficient and straightforward than the finite element analysis, for performing the static, free vibration, time domain, and frequency domain analyses.
395

Analyse du comportement au feu des planchers mixtes acier-béton constitutés de poutres cellulaires / Analysis of the fire behaviour of steel and concrete composite floors made of cellular beams

Bihina, Gisèle 05 July 2011 (has links)
En situation d’incendie, la dégradation des propriétés mécaniques des matériaux constitutifs d’une structure peut sensiblement en modifier le comportement global. Ainsi, lors d’essais au feu ou de sinistres réels, des flèches significatives sont observées sans ruine globale du plancher. Ceci traduit l’activation d’un mécanisme basé sur une borne supérieure de plasticité en grands déplacements et appelé effet membrane. Ainsi, malgré la perte des propriétés du béton, de l’acier d’armatures et de l’acier de construction des poutres connectées à une dalle en béton armé ou mixte acier-béton, la capacité portante de cette dalle se définit comme une fonction croissante de sa flèche. En pratique, le comportement complexe des planchers mixtes acier-béton peut être appréhendé par des modèles dits simplifiés ou avancés, suivant le niveau de précision souhaité. La méthode analytique FRACOF permet par exemple d’étudier un plancher global à température élevée, en se basant sur les modèles de comportement simplifiés des matériaux, acier et béton, définis dans les Eurocodes. Par cette méthode, la capacité portante d’une dalle peut alors être déterminée en tenant compte des profilés métalliques connectés à la dalle, et de l’activation d’un effet membrane en grands déplacements. Cette méthode analytique a été validée par une comparaison à des modèles éléments finis, ainsi qu’à des résultats d’essais au feu en grandeur nature. Elle est applicable à des profilés en acier laminé à chaud avec des portées pouvant atteindre 20 m. Or le franchissement de ces portées nécessite des sections de poutre à forte inertie, afin de limiter les flèches du plancher en service. Pour limiter la quantité d’acier que requerraient de telles poutres, le recours à des poutres cellulaires est une solution pratique et esthétique. Un modèle élément finis de poutres cellulaires en acier seul et mixtes est proposé dans le cadre de la thèse de doctorat. Le comportement thermo-mécanique des poutres cellulaires en acier seul est modélisé sous le code Cast3M. Les poutres mixtes sont modélisées en combinant un calcul de transfert thermique sous Cast3M et une analyse mécanique sous ANSYS. Les poutres en acier et la dalle en béton ou mixte sont représentées par des éléments de type coque. Les connecteurs sont représentés par des éléments de type poutre. Ce modèle tridimensionnel tient par ailleurs compte des non-linéarités matérielle et géométrique. Il est confronté à des résultats d’essais à températures normale et élevée. La validation du modèle est suivie d’une comparaison à une méthode analytique existante pour en vérifier la précision et le degré de conservatisme. Les poutres cellulaires sont ensuite étudiées en tant que partie intégrante de planchers mixtes acier-béton sous incendie. Un essai en grandeur nature sous feu réel met en évidence l’activation d’un effet membrane en présence de poutres cellulaires non-protégées, sans ruine du plancher. Les résultats de l’essai sont utilisés pour calibrer un modèle élément fini tridimensionnel. La calibration est effectuée en s’appuyant sur la distribution des températures dans les différents composants du plancher, la durée de résistance au feu, la forme des déformées et les modes de ruine. Ensuite, le modèle, qui peut reproduire le comportement thermo-mécanique d’un plancher mixte, est utilisé pour évaluer une proposition d’extension de la méthode FRACOF à des planchers mixtes comportant des poutres cellulaires. / In a fire situation, the decrease of the material properties of a structure can significantly modify its overall behaviour. Hence, during fire tests or real fires, very large deflections can be observed on a floor without any global collapse. This highlights the activation of a large-displacement plastic upper bound mechanism called membrane action. Thus, in spite of the property loss of concrete, reinforcement steel and constructional steel of the beams connected to a reinforced concrete or composite slab, the load bearing capacity of this slab is defined as an increasing function of its vertical deflection. In practice, the behaviour of composite steel and concrete floors can be assessed with simplified or advanced models, depending on the expected level of precision. For instance, the analytical method named FRACOF enables to study a whole floor at elevated temperatures, on the basis of the Eurocodes simplified models for the behaviour of steel and concrete. With this method, the load bearing capacity of a slab can then be estimated taking account of steel profiles connected to the slab and tensile membrane action in large displacements. This analytical method has been validated against finite elements models as well as results from full scale fire tests. It applies to hot-rolled steel profiles spanning up to 20 m. However, such spans require sections with a great moment of area to limit the floor deflection in serviceability state. In order to limit the amount of steel required, cellular beams can be utilized as a practical and aesthetical solution. A finite element model for steel and composite steel and concrete cellular beams is proposed in the scope of the PhD thesis. The thermo-mechanical behaviour of steel cellular beams is modelled under Cast3M code. Composite beams are modelled combining a heat transfer calculation under Cast3M to a mechanical analysis under ANSYS. The steel beams and the reinforced or composite slab are modelled with shell elements. The shear studs are modelled with beam elements. Besides, this 3D model takes into account both material and geometrical nonlinearities. It is compared with tests results at both normal and elevated temperatures. Once validated, the model is compared to an existing analytical method in order to check the precision and the level of conservatism of the latter. Then, cellular beams are studied as part of composite steel and concrete floors in a fire situation. A full-scale natural fire test puts into evidence tensile membrane action with unprotected cellular beams, without any overall collapse. The test results are used for calibrating a 3D finite element model. This calibration relies on the temperature distribution in the different parts of the floor components, the fire resistance degree, the deformed shape and the failure modes. The model, which can reproduce the thermo-mechanical behaviour of a composite floor, is then utilized for assessing an extension proposal of the FRACOF method to composite floors made of cellular beams.
396

En jämförelse mellan KL-trä och betong som bjälklagssystem : Ett experiment med multikriterieanalys / A Comparison Between CLT-wood and Concrete as a Structrural Floor System : An Experiment with Multicritery Analasys

Gustavsson, Anton, Gudjonsson, Julius January 2021 (has links)
Syfte: Miljömedvetet och prisvärt byggande har länge varit två uttryck som använts ibyggbranschen. Betong har använts och är väl beprövat. Trä och framförallt KL-trä ärdäremot ett material som växt fram det senaste decenniet. Frågan är, när är det bäst attbygga med de olika materialen och vad är materialens respektive klimatavtryck? Målet med denna rapport är att jämföra två bjälklagssystem, ett i KL-trä och ett i betong, utifrån ett sammanvägt kostnads-, dimensions- och miljöperspektiv och hur de förhåller sig mellan spännvidderna fyra, sex och åtta meter. ▪ Hur stor är den procentuella kostnadsskillnaden mellan dessa bjälklagssystem? ▪ Hur stor är den procentuella skillnaden i koldioxidutsläpp under produktionen avdessa bjälklagssystem ▪ Hur stor är den procentuella dimensionsskillnaden mellan dessa bjälklagssystem? ▪ Vilket bjälklagssystem är det bästa valet utifrån en multikriterieanalys? Metod: Studien består av flera experiment för att få ut empiri till en kvotmätning.Denna metod användes för att få fram primärdata till arbetet.Sekundärdata samlades in via dokumentstudier av lagar och krav för byggnation inombrand, ljud och dimensionering. Resultat: Studien visar resultaten av en jämförelse mellan bjälklagssystem med olikamaterial och spännvidder. En multikriterieanalys används för att rangordna resultatenför att visa det mest fördelaktiga alternativet. Konsekvenser: Vid användning av KL-trä bör dimensionering tas i beaktande dådimensionerna blir relativt stora jämfört med betong. Kostnaden av materialen skiljersig markant. Detta speglar dock inte totalkostnad då produktion, leveranser, montering,etcetera ej är medräknat. Att använda en multikriterieanalys vid jämförelser ger entydlig bild på fördelaktigt alternativ samt hur stor skillnad det är mellan alternativen. Begränsningar: Då det endast är en del i totalkostnaden som berörs speglar interesultatet rättvis kostnadsbild och kan därför inte användas som referenspunkt. Resultatfungerar endast som ett hjälpmedel vid delberäkning av totalkostnad. Nyckelord: Betong, KL-trä, Plattbärlag, Plattbjälklag, Kassettbjälklag,Multikriterieanalys, Dimensionering, Kostnad, Koldioxidutsläpp / Purpose: Environmental and affordable construction has long been two terms used in theconstruction industry. Concrete has been used and is well proven. Wood and especiallyCLT wood, on the other hand, is a material that has emerged in the last decade. The questionis, when is it best to build with the different materials and what are their respective climatefootprints? The aim of this report is to compare two structural floor systems, one in CLT wood and onein concrete, based on a balanced cost, dimension and environmental perspective and howthey relate between the spans of four, six and eight meters. ▪ What is the percentage cost difference between these structural floor systems? ▪ What is the percentage difference in carbon dioxide emissions during theproduction of these structural floor systems? ▪ What is the percentage dimensional difference between these structural floorsystems? ▪ Which structural floor system is the best choice based on a multi-criteria decisionanalysis? Method: The study consists of several experiments to obtain empirical data for a quotameasurement. This method was used to obtain primary data for the work. To obtain secondary data consisting of standards, calculation models and requirements, adocument study was used. Secondary data were collected via document studies of laws and requirements forconstruction in fire, acoustics and dimensioning. Findings: The study shows the results of a comparison between structural floor systemswith different materials and spans. A multi-criteria decision analysis is used to rank theresults to show the most advantageous alternative. Implications: When using CLT-wood, dimensioning should be taken into account as thedimensions will be relatively large compared to concrete. The cost of the materials differsmarkedly. However, this does not reflect the total cost as production, deliveries, assembly,etcetera are not included. Using a multi-criteria decision analysis in comparisons gives aclear picture of a favorable alternative and how large a difference there is between thealternatives. Limitations: As only a part of the total cost is affected, the result does not reflect a faircost picture and can therefore not be used as a reference point. The results only serve as anaid in the partial calculation of total cost. Keywords: Concrete, CLT-wood, Prefabricated Concrete Slab Joist, CLT Flat Joist,Rib Elements, Multi-Criteria Decision Analysis, Cost, Carbon Dioxide Emissions
397

Železobetonová konstrukce / The reinforced concrete structure of elementary school

Benešová, Lenka January 2018 (has links)
The diploma thesis is focused on the design and evaluation of the concrete monolithic ceiling slab in the shape of semicircular ring, ribs lining this plate and skylights. The result is static calculation and drawing documentation.
398

Vícepodlažní budova / Multi-storey building

Cmajdálková, Alžběta January 2018 (has links)
The subject of the master’s thesis is static design and assessment of the static load-bearing steel structure. The structure is designed for the site Brno. Specifically this is an eight-storey office building with a 54 x 12 m floor plan and a total height is 30,2 m. The steel structure is lovated betwrrn teo reinforced concrete towers secure for vertical transport. The structure is designed in three variants. In the one of them a steel frame with hingee attached elements. The ceiling structure is designed as composite steel and concrete structure.
399

Statické řešení železobetonové konstrukce / Static solution of reinforced concrete structure

Mašek, Petr January 2018 (has links)
This diploma thesis deals with study of feasibility of waterpark monolithic reinforced concrete structure with roof terrace. This structure has one underground floor, which has water park utility function and two above ground floors. On the roof is terrace with grass, mobile bar and with space to relax. Subject of this diploma thesis is the main loadbearing frame, which has span 32 m. The structure is assessed according to limit states of valid norms and also takes into account construction stages and time dependent analysis. The structure is calculated on beam and slab-plate structural models. Structural analysis and general drawings are done.
400

Polyfunkčný dom Brno-Řečkovice / Multifunctional building, Brno-Řečkovice

Kašuba, Patrik January 2018 (has links)
The aim of the diploma thesis is processing of the design documentation to execution newly-built multifunctional building in the city part Brno - Řečkovice. Multifunctional building is a detached house, which is located in a quiet area on the edge city. This is a five floor building with four floor, one basement and flat roof. Building is rectangular shape. At the object are twelve parking spaces for cars. Vertical load-bearing structure are made of masonry and reinforced frame system, reinforced concrete floor and prestressed hollow core slab Spiroll. External facade building is created by render scrape texture and flush facade in ground floor.

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