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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

Bétons de granulats de bois : étude expérimentale et théorique des propriétés thermo-hydro-mécaniques par des approches multi-échelles / Wood aggregate concretes : experimental and theoretical study of thermo-hydro-mechanical properties using multi-scale approaches

Akkaoui, Abdessamad 07 November 2014 (has links)
Les bétons végétaux, composés de particules végétales et d'un liant minéral ou organique, constituent une solution à explorer pour limiter l'impact environnemental du bâtiment. Utilisés principalement pour leurs performances thermiques, ces matériaux suscitent l'intérêt de plusieurs organismes de recherche ainsi que de plusieurs entreprises industrielles. La généralisation de leur utilisation dans la construction ne sera pas possible sans résoudre certains problèmes liés à leurs techniques de mise en œuvre, à leur certification et à leur durabilité. Le présent travail a pour objectif de contribuer à la caractérisation de ces matériaux complexes. Il s'agit en particulier d'étudier les comportements mécanique, thermique et hydromécanique du béton de granulats de bois. La stratégie utilisée consiste à combiner l'expérience et la modélisation pour mieux comprendre les mécanismes mis en jeu. Le module de Young et la résistance en compression ont été mesurés expérimentalement à l'aide de la technique de corrélation d'images numériques. L'évolution de ces propriétés dépend des conditions de conservation, de la durée de séchage ainsi que de la teneur en ciment. En raison de l'orientation aléatoire des granulats de bois, le comportement mécanique du béton est isotrope. Un modèle d'homogénéisation basé sur le schéma autocohérent a été développé pour prédire le module de Young du béton et ses résultats sont très satisfaisants. Les mesures de la conductivité thermique montrent que celle-ci reste constante en conditions endogènes. La modélisation de cette propriété par le schéma autocohérent conduit à des résultats cohérents avec les mesures expérimentales. En conditions de dessiccation, la conductivité thermique dépend linéairement de la densité du béton. L'évolution de la conductivité thermique des granulats de bois et de la pâte de ciment au cours du séchage a été modélisée grâce au schéma de Mori-Tanaka. Ces évolutions ont été intégrées dans le modèle autocohérent qui fournit ainsi des résultats satisfaisants, mais qui pourrait être amélioré si l'on disposait des courbes de sorption/désorption des constituants du béton. Les variations dimensionnelles du béton au cours du temps dépendent des conditions de conservation, mais pas de la direction de mesure, ni de la teneur en ciment. Un modèle reposant sur une combinaison des déformations induites par la désorption de l'eau par des constituants et le transfert d'humidité entre ceux-ci a été proposé et a permis de capturer les tendances des déformations du béton sauf au jeune âge. À l'échelle locale, l'étude a montré que les déformations du béton sont du même ordre de grandeur que celles de la pâte de ciment. Elle a aussi mis en évidence un endommagement partiel de l'interface granulat/liant qui mériterait à être pris en compte dans la modélisation / Environmentally-friendly concretes, made up of plant-based particles and mineral or organic binder, are solutions worth exploring to reduce the environmental impact of buildings. Mainly used for their thermal performance, these materials have aroused interest of many research organisations and industrial companies. Their widespread use in construction is not possible without resolving some technical problems related to their implementation, certification and durability. This work aims to contribute to characterize these complex materials, in particular to study the mechanical, thermal and hydromechanical behaviors of wood-aggregate concrete. Modeling and experiments have been used to understand the complex mechanisms involved. The Young's modulus and the compressive strength were experimentally measured using digital image correlation. The evolution of these properties depends on the conditions of storage, the drying time and the cement content. Because of the random orientation of the wood aggregates, the material exhibits isotropic behavior. A homogenization model based on a self-consistent scheme was developed to predict the Young's modulus. The results were satisfactory. Measurements show that thermal conductivity remains constant under sealed conditions. The modeling of this property with the self-consistent scheme gives results consistent with experimental measurements. In desiccation conditions, the thermal conductivity depends linearly on the density of concrete. The evolution of the thermal conductivity of the wood aggregates and the cement paste during drying was modeled with the Mori-Tanaka scheme. These evolutions were integrated into the self-consistent model, which yielded satisfactory results, but could be improved if sorption/desorption curves of the phases were available. The macroscopic dimensional variations of the wood-aggregate concretes depended on the storage conditions, but not on the measurement direction, nor on the cement content. A model based on the combination of the strains induced by the desorption of water from the phases and the moisture transfer between them was proposed. It allowed us to capture the trends of the strains of our concrete except at early age. At a local scale, the study showed that the strains of concrete were close to those of the cement paste. The study also shed light on a significant damage of the aggregate/binder interfaces, which would deserve to be taken into account into the modeling
2

Organická soudobá architektura a bydlení / Organic architecture and contemporary residential living

Čábelková Nahorniaková, Marcela January 2012 (has links)
Organic architecture is often used term especially in connection with the daring and experimental form. The exact definition or division is still missing. The founder of modern organic architecture is to be generally considered as Frank Loyd Wright. He was the man who created organic architecture and also made first definition in the early twentieth century, when formulating new architectural styles. Dissertation deals with insufficiently described problem of organic architecture. The main focus is on contemporary production of residential organic architecture in Central Europe. Especially on the particular realizations in Hungary, Czech Republic, Slovak Republic, Austria, Germany and Poland. Beside detail description of European realizations, the dissertation deals also with foundations of organic architecture in U.S.A. and important realizations here. Modern organic architecture primarily originated in the United States of America. The work presents most important contemporary realizations and architects creating resident living organic architecture in other countries around the world in order to complete the overview. The objective of dissertation was describing newest trends in designing buildings for living. Find position of organic architecture and give reasons for it´s increasing popularity, spread and necessity for new development in architecture according to the new trends. Organic architecture is an alternative way of contemporary residential living. It´s popularity is growing in last years in response to the development of modern technologies and materials, the need to protect our natural resources and also to the increasing negatives of globalization and to denial of local traditions and regional specificities. Aspects of organic forms were divided into three main groups according to their main characteristics: form, harmony and sustainable development. Another objective was find location of contemporary organic residential architecture in Czech Republic and abroad. It is rather spread all over the world than concentrated on certain places. Therefore I selected countries that are richer than the others on the occurrence of organic buildings. The objective was also to address architects, specialists, public and especially university teachers of architecture and students themselves. Communication with them was mainly connected with grant project in 2010. The theme of grant project was contemporary organic architecture in residential living. There were lectures about contemporary organic architecture and exhibition on the theme: Contemporary living organic architecture. The publication of the catalog was published under the title: Contemporary organic houses - Europe. I had the opportunity to visit a number of organic family houses abroad. Specifically houses in Slovakia, Hungary and Germany. Results of survey, which was realized by questions to owners and authors of chosen buildings, are included in dissertation. The mail results of dissertation are - make a detail review of organic architecture in residential living - define trends in contemporary organic architecture and residential living - obtain and process answers from owners and authors of chosen buildings within survey - analysis of organic house ( houses) in city planning and landscape - publication of catalogue focused on organic contemporary European houses - article about contemporary organic architecture and residential living will be published in 2012 on archiweb page

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