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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.
101

Stavební průzkum a diagnostika zděné konstrukce / Survey and Diagnostics of Masonry Construction

Bakešová, Martina January 2015 (has links)
The aim of my master’s thesis is to develop a brief overview of the historical development of brick, diagnosis methodologies of masonry structures and their application in the practical part for evaluation of structural survey masonry, carried out at the Faculty of Philosophy, Masaryk University in Brno.
102

Experimental and numerical study of confined masonry walls under in-plane loads : case : guerrero State (Mexico)

Sánchez Tizapa, Sulpicio 10 December 2009 (has links) (PDF)
This research work proposes methods to rises the resistance and to evaluate the behavior of confined masonry walls built from clay solid bricks. These elements are widely used in Guerrero State (México) to build masonry structures, which should resist high lateral loads because of the serious seismic hazard. Therefore, a large experimental program to evaluate the mechanical properties of bricks and masonry currently required in the design process and masonry analysis was developed. To rises the masonry resistance and to counteract the influence of the compressive strength of the pieces on the masonry behavior, a high compressive strength mortar and a metallic reinforcement inside the joints were used. With respect to referenced values of the mechanical properties, some were similar and others were twice bigger. In this country zone, the first three tests under lateral load on full-scale confined masonry walls built from clay solid bricks were carried out in order to evaluate its behavior. A reinforcement composed by metallic hexagonal mesh-mortar coat was placed on the faces of two walls to rise or to restore the resistance. The walls showed good behavior and the reinforcement had adequate structural efficiency. Numerical models of panels and walls built by using the experimental data evaluated the envelope resistance, the failure mode and showed the influence of the mechanical properties of the pieces and joints on the global behavior. Two models had metallic reinforcement inside the joints. In addition, a constitutive law of the masonry defined from experimental results allowed to elaborate a simple model, which results were concordant with respect to the experimental results and similar to those calculated by complex models. Finally, two simplified models to evaluate the resistance of confined masonry walls by considering the failure plane on the wall diagonal were developed. One supposes the masonry failure by shear effect and the other supposes the masonry failure by induced tension. The ratio theoretical resistance vs. experimental resistance was adequate for walls built from different materials and tested under different loads, which had ratio Height/Length ranging from 0.74 to 1.26
103

Análise da viabilidade técnica do resíduo de celulose e papel em tijolos de adobe / Technical viability analysis of cellulose and paper residual mud utilization in adobe bricks

Battistelle, Rosane Aparecida Gomes 29 November 2002 (has links)
Atualmente, o reaproveitamento de resíduos resultantes de atividades industriais vem se tornando um dos pontos mais importantes na melhoria dos aspectos produtivos, como também na minimização de problemas ambientais decorrentes da forma de produção e do descarte final do resíduo gerado no decorrer do processo de produção. Desta maneira, as indústrias estão buscando implantar um sistema de gestão ambiental (SGA), no qual o resíduo, anteriormente descartado, passa a ser considerado matéria prima para a fabricação de novos materiais. Dentro deste enfoque, e considerando os impactos gerados pelas indústrias de papel e celulose, estudos que visam demonstrar o potencial de utilização do lodo residual gerado durante a produção de papel na indústria Votorantim Celulose e Papel (VCP), município de Jacareí, SP-Brasil, têm sido desenvolvidos, por meio de uma parceria de indústria e universidades (UNESP - Bauru e USP - São Carlos). Após análises químicas e toxicológicas do lodo residual, obteve-se uma composição de aproximadamente 58,9% de fibras, sendo classificado como Classe II, segundo a NBR 10.004/87. Para avaliar o seu potencial de utilização em materiais de construção, foram confeccionados tijolos de adobe com o solo arenoso proveniente do município de Bauru, SP, nos traços 0%, 10%, 15%, 20%, 25%, 30% e 40% em volume de resíduo. Foram realizados diversos ensaios para caracterização dos tijolos (retração, absorção de água e resistência à compressão simples), bem como ensaios de intemperismo, gotejamento, verificação da ação do fogo (perda de massa, propagação das chamas e ensaio de incombustibilidade dos materiais de construção), como também a obtenção de suas características térmicas e acústicas. Com os resultados dos ensaios, foi realizada uma análise geral, por meio da interação dos melhores valores encontrados e, assim, escolhido o traço numa faixa de 20% a 25% de resíduo. Os resultados demonstraram a viabilidade do uso do resíduo em tijolos de adobe, conferindo aos mesmo bons níveis de resistência, manuseio, leveza e durabilidade. / Nowadays, reuse of residues from industrial activities is one of the most important aspects in productivity improvement, as well as, minimization of environmental problems originated from production way and residue disposal during the productive process. Industries are requesting and Environmental Management System (SGA), in which residues, formerly discarded, began to be considered raw materials for production of new materials. In this context and considering impacts generated by paper and cellulose manufacturing, studies have been developed, aiming to demonstrate potential use of residual mud generated during paper production in Votorantin Cellulose and Paper Industry (VCP), located in Jacareí, São Paulo State, Brazil, through a partnership between this industry and universities (UNESP - Bauru and USP - São Carlos). After chemical and toxicological analyses of the residual mud, a composition of aproximately 58,9% of fibres was obtained and classified as Class II acording to NBR 10.004/87. For evaluating its potential use in buildings, adobe bricks were made with sandy soil from Bauru (São Paulo State), considering 0% (witness), 10%, 15%, 20%, 25%, 30% and 40% of residuary volume. Several rehearsals were carried out for brick characterization (retraction, water absorption and resistance to simple compression), and to verify intemperism, leak and fire action (mass loss, flame propagation and fireproof rehearsals), as well as thermal and acoustic characteristics (qualities). A general analysis interacting all values obtained indicated the percentage of residuary volume, in the range of 20% to 25% as the best condition. The results demonstrated viability of use of paper and cellulose residual mud in adobe bricks manufacturing, since they presented good levels of resistance, handling, lightness and durability.
104

Modélisations thermomécanique et numérique du comportement de maçonneries en briques alvéolées en terre cuite sous chargements mécanique et thermique sévères / Thermo-mechanical and numerical modeling of the behavior of hollow clay brick masonry under severe mechanical and thermal load

Sridi, Ahmed 25 April 2018 (has links)
Un des enjeux majeurs de la filière de construction en briques alvéolées est l’amélioration de la tenue au feu de hauts et ambitieux bâtiments, réalisés avec ces briques. L’objet de nos travaux est de développer des modèles thermo-mécaniques et des outils numériques suffisamment prédictifs pour orienter la recherche, par la simulation numérique, de produits améliorés vis-à-vis de la tenue au feu, permettant de diminuer le nombre de coûteux essais expérimentaux. Les contributions principales sont d’ordre méthodologique. Nous avons ainsi établi un dialogue entre les observations, les mesures et les résultats expérimentaux, d’un côté, les modèles et les simulations de l’autre, avec un souci permanent de diminution des coûts des simulations. Ainsi, tirant profit de résultats de mesures réalisées, nous avons développé progressivement des modélisations adaptées, en examinant l’importance des phénomènes thermiques (conduction, convection et rayonnement), en recherchant les « juste-bonnes» (par rapport aux objectifs) relations d’échanges aux multiples interfaces du problème et en introduisant le changement de phase de l’eau liée. Nous avons également été amenés à identifier, par approche inverse, certains paramètres, après avoir identifié les bons mécanismes thermo-mécaniques. Enfin, pour mieux inscrire nos travaux dans une démarche d’aide efficace à la conception, nous avons travaillé dans le cadre multimodèle et multiéchelle Arlequin pour formuler, approcher et résoudre les problèmes thermo-mécaniques résultants, comportant des zones de concentrations du gradient thermique et de singularités mécaniques. L’approche globale, élaborée et testée, en utilisant différents codes et en développant des parties d’autres, montre une capacité réelle à améliorer les calculs des structures en briques alvéolées, soumises à des chargements thermo-mécaniques. / One of the major challenges of the hollow clay brick industry nowadays is to improve the fire resistance of ambitiously tall buildings, constructed with this type of bricks. The objective of our work is to develop thermo-mechanical models and related predictive numerical tools to guide the research of improved fire-performance products and therefore reduce the number of expensive experimental tests. Our main contributions are methodological. With a permanent concern of reducing the simulation costs, we establish a dialogue between observations, measurements and experimental results, on the one hand, models and simulations on the other hand. In this regard, measurements, obtained during the experimental tests we carried out, are used to progressively develop relevant models, by examining the importance of thermal phenomena (conduction, convection and radiation), by looking for the just right transfer relations (with respect to our objectives) at the multiple interfaces of the problem and by considering the phase change of bound water. After identifying the good thermo-mechanical mechanisms, we calibrate some numerical parameters by solving an inverse problem. Moreover, to efficiently help the design of new products, we employ the multi-model and multi-scale Arlequin framework to formulate, approximate and solve resulting thermo-mechanical problems. The latters include areas of thermal gradient concentrations and mechanical singularities. Our global approach implemented and tested by developing codes and enriching others, shows a real ability of our methodology to efficiently compute structures made of hollow bricks, when subjected to thermomechanical load.
105

Adição de resíduo de argamassas mistas na produção de tijolos modulares de solo-cimento / Addition of the mixed waste of mortar production of bricks of modular soil-cement

Rodrigues, Mayza Loureiro Araújo January 2008 (has links)
Submitted by Carla Ferreira (carlaferreira66@gmail.com) on 2014-07-30T15:27:14Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) dissertacaomaysaloureiro (1).pdf: 976602 bytes, checksum: 1b7c4f7eb5e4cd083611f0ebc69ff8d0 (MD5) / Made available in DSpace on 2014-07-30T15:27:14Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) dissertacaomaysaloureiro (1).pdf: 976602 bytes, checksum: 1b7c4f7eb5e4cd083611f0ebc69ff8d0 (MD5) Previous issue date: 2008 / CAPES / xxxxxxx / xxxxxxxxx
106

O barro cinzento paulista: produção em barro cozido nas olarias do Tijucusú e de Pinheiros. Ordem de São Bento em São Paulo entre o século XVI e o XIX / The paulista grey clay: terracota production in Tijucusú and Pinheiros potteries. Saint Benedict\'s Order in São Paulo between the 16th and 19th centuries

Vieira, Edileine Carvalho 08 November 2016 (has links)
A pesquisa pretende levantar através de documentação disponível, além de outras fontes, informações sobre as origens da produção em barro cozido nas olarias da Vila de Piratininga, ou como iremos tratá-la aqui, Vila de São Paulo, especialmente sob a administração da Ordem Beneditina, no período entre 1560 e 1870. Trataremos de identificar as técnicas de produção empregadas na elaboração das peças produzidas nestas olarias, como telhas, tijolos, louças, etc, sobretudo, nas olarias da Fazenda do Tijucusú pertencentes à Ordem Beneditina e na olaria da Vila de Pinheiros administrada pelos beneditinos. Investigaremos a documentação disponível sobre as olarias e pretendemos demonstrar as técnicas e as finalidades de uso das peças ali produzidas, assim como em outras olarias da Vila de São Paulo no período citado, na tentativa de confirmar a existência efetiva de uma indústria oleira consistente e uma mão de obra especializada. / The research intends to raise through available documentation, and other sources, information about the origins of production in terracota in the brick kilns of Piratininga village or how we treat it, Vila Sao Paulo, especially in the administration of the Benedictine\"s Order in the period between 1560 and 1870. We will try to identify the production techniques used in the preparation of the pieces produced in these brick kilns, such as tiles, bricks, crockery, etc., and especially the potteries of Tijucusú Treasury belonging to the Benedictine Order and the pottery of Pine Village run by the Benedictines. We investigate the available documentation on these potteries and we intend to demonstrate the techniques and the use purposes of there produced parts, as well as in other potteries from the town of São Paulo in the period mentioned in an attempt to confirm the actual existence of a consistent potter industry and a skilled labor.
107

Studies On Shear Bond Strength - Masonry Compressive Strength Relationship And Finite Element Model For Prediction Of Masonry Compressive Strength

Uday Vyas, V 12 1900 (has links)
Masonry is a layered composite consisting of mortar and the masonry unit. Perfect bond between the masonry unit and the mortar is essential for the masonry to perform as one single entity in order to resist the stresses due to various loading conditions. Nature of stresses developed in the masonry unit and the mortar and the failure pattern of masonry subjected to compression greatly depends upon the relative stiffness of the masonry unit and the mortar. The thesis is focused on (a) some issues pertaining to masonry unit – mortar bond strength and its influence on masonry compressive strength, and (b) developing a finite element (FE) model to predict the compressive strength of masonry. Importance of masonry bond strength and masonry behaviour is highlighted in chapter 1. Characteristics of masonry units and mortars used in the investigations are presented in Chapter 2. Two types of soil-cement blocks with widely varying strength and elastic properties and cement-lime mortars of two different proportions were used in the investigations. Results of stress-strain relationships and other characteristics were determined for the blocks as well as for mortars. Block-mortar combinations were selected to have block modulus to mortar modulus ratio of <1.0, ~1.0 and >1.0. Different artificial methods of enhancing the shear bond strength of masonry couplets have been discussed in chapter 3. Shear bond strength of the masonry couplets was determined through a modified direct shear box test apparatus. Without altering the block and mortar properties, bond strength values for three block-mortar combinations were generated through experiments. Effect of pre-compression on shear bond strength has also been examined for certain block-mortar combinations. Considering five different bond strength values and three block-mortar combinations, compressive strength and stress-strain characteristics of masonry was obtained through the tests on masonry prisms. A detailed discussion on influence of shear bond strength on masonry compressive strength is presented. Major conclusions of the investigation are: (a) without altering the block and mortar characteristics shear bond strength can be enhanced considerably through the manipulation of surface texture and surface coatings, (b) masonry compressive strength increases linearly as the shear bond strength increases only for the combination of masonry unit modulus less than that of mortar modulus, (c) masonry compressive strength is not sensitive to bond strength variation when the modulus of masonry unit is larger than that of the mortar. Chapter 4 is dedicated to the development of a 3D FE model to predict the masonry compressive strength. Literature review of empirical methods/formulae and some failure theories developed to predict masonry strength are presented. Existing FE models for masonry dealing with both macro and micro modelling approaches are reviewed. The proposed FE model considers (a) 3D non-linear analysis combined with a failure theory, (b) uses multi-linear stress-strain relationships to model the non-linear stress-strain behaviour of masonry materials, (c) adopting Willam-Warnke’s five parameter failure theory developed for modelling the tri-axial behaviour of concrete, and (d) application of orthotropic constitutive equations based on smeared crack approach. The predicted values of masonry compressive strength are compared with experimental values as well as those predicted from other failure theories. The thesis ends with a summary of conclusions in chapter 5.
108

Αξιοποίηση της Ερυθράς Ιλύος στη βιομηχανία παραδοσιακών κεραμικών / Utilisation of Red Mud in the heavy clay industry

Ποντίκης, Ιωάννης 05 November 2007 (has links)
Στην παρούσα Διατριβή παρουσιάζεται η μελέτη της δυνατότητας αξιοποίησης της ερυθράς ιλύος, ΕΙ, η οποία παράγεται κατά τη διαδικασία παραγωγής της αλουμίνας με τη διεργασία Bayer, για την παραγωγή δομικών παραδοσιακών κεραμικών, κύρια τούβλων και κεραμιδιών. Μελετήθηκαν αργιλούχα μίγματα με ΕΙ για ποσοστά ΕΙ από 10%κβ έως και 100%κβ.Επιγραμματικά, για την ΕΙ, πραγματοποιήθηκε χαρακτηρισμός και μελέτη της θερμικής συμπεριφοράς της. Για τα μίγματα της ΕΙ με αργιλούχες Α' ύλες, πραγματοποιήθηκε θεωρητικός σχεδιασμός τους, ενώ μελετήθηκε η επίδραση των σταδίων ανάμιξης και λειοτρίβησης, η επίδραση της ΕΙ στην πλαστικότητα, η θερμική συμπεριφορά, οι φυσικομηχανικές ιδιότητες των τελικών κεραμικών, η επίδραση της θερμοκρασίας και ατμόσφαιρας όπτησης καθώς και η περιβαλλοντική τους συμπεριφορά. Πραγματοποιήθηκαν επιπρόσθετα πιλοτικές δοκιμές παραγωγής τούβλων και κεραμιδιών. Τα αποτελέσματα της διατριβής, οδήγησαν στην ανάπτυξη μιας βέλτιστης διεργασίας παραγωγής κεραμικών με ΕΙ, η οποία αφορά στο σχεδιασμό του μίγματος με ΕΙ και την όπτησή του σε αναγωγικές συνθήκες. / In the present thesis, Bayer's process red mud, RM, is being studied as an additive and raw material for the production of heavy clay ceramics, mainly bricks and roofing tiles. A number of clay mixtures with RM were studied, for a RM content ranging from 10wt% to 100wt%. In summary, RM was characterised and studied for its thermal behaviour whereas, for the clay mixtures with RM, their design is provided, and the effect of comminution steps, the effect of RM on plasticity, their thermal behaviour, the influence of firing temperature and atmosphere, the physicomechanical properties of the end bodies, as well as their environmental behaviour are studied. In addition, pilot plan scale experiments were performed for the production of bricks and roofing tiles. The results of this thesis, led to the development of an optimised process for the production of ceramics with RM, which emphasises on the design of the body mixture as well as on the firing in reducing conditions.
109

Historie a současnost těžby rašeliny v Borkovických blatech / History and present of peat extraction on the area Borkovická blata

ŠTĚCHOVÁ, Monika January 2011 (has links)
In the general section of this thesis are shortly characterized fossil fuel, peat bogs and peat, process of their origin, their types and importance. Another important part of this work is the extraction of peat, its trend, subsequent restoration and environmental problem of the peat extraction. The main part is the characteristic of the area Borkovická blata, mapping out mining process in the area and the present condition. Furthermore, there is shortly characterized the company Rašelina, a. s., which extracted in Borkovická blata peat for a long time and is still engaged in the extraction and processing of peat.
110

Simulação e experimentação da secagem de tijolos cerâmicos vazados. / Simulation and experimentation of the drying of drained ceramic bricks.

SILVA, Joselito Barbosa da. 06 September 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-06T19:10:49Z No. of bitstreams: 1 JOSELITO BARBOSA DA SILVA - TESE PPGEP 2009..pdf: 24353415 bytes, checksum: af00c2bf379ee7a0fedb0f2e9164b959 (MD5) / Made available in DSpace on 2018-09-06T19:10:49Z (GMT). No. of bitstreams: 1 JOSELITO BARBOSA DA SILVA - TESE PPGEP 2009..pdf: 24353415 bytes, checksum: af00c2bf379ee7a0fedb0f2e9164b959 (MD5) Previous issue date: 2009-12-17 / CNPq / Capes / Com aplicação nos mais variados setores, os materiais cerâmicos podem ser utilizados para fabricação de utensílios domésticos, materiais para construção civil e até mesmo revestimento de naves espaciais. Na fabricação de tijolos cerâmicos (por exemplo, na conformação e/ou secagem) podem surgir danos estruturais como trincas, deformações e empenamentos que diminuem a qualidade do produto final. A secagem é um processo termodinâmico, no qual ocorre a redução do teor de umidade do sólido, mediante o fornecimento de energia ao mesmo. Com o estudo das simulações computacionais capazes de prever o comportamento de variáveis como teor de umidade, temperatura e tensões no interior dos tijolos cerâmicos, é possível obter um processo de secagem mais rápido e otimizado, evitando desperdícios de matérias-primas e economia de combustíveis. Buscando melhorias para o processo de secagem de tijolos cerâmicos, este trabalho apresenta um estudo numérico e experimental da secagem de tijolos vazados. Um modelo matemático tridimensional transiente é apresentado para predizer a transferência de massa e calor e simular a distribuição do teor de umidade, temperatura no interior do sólido, considerando simetria em torno do centro do sólido, propriedades termofísicas constantes e variação de volume (encolhimento). Para validação da metodologia numérica foram realizados experimentos de secagem com tijolos cerâmicos vazados industrial de oito furos doados pela Cerâmica Cincera, localizada no município de Santa Rita-PB. Nos experimentos, foram usadas temperaturas de secagem de 50, 60, 70, 80, 90 e 100°C. Verificou-se que para temperaturas de 50 e 60°C e umidades relativas de 20,8% e 13,5% respectivamente a velocidade de secagem é menor, diminuindo os riscos de defeitos no produto. Já nas temperaturas de secagem de 80, 90 e 100°C, surgem altos gradientes de temperatura e umidade no interior do tijolo que geram tensões termo-hídricas, ocasionando grandes fissuras e trincas, principalmente nas regiões dos vértices e paredes internas dos furos principalmente no início do processo, diminuindo aparentemente com o tempo de processo devido as contrações da camada exterior e superior. / With application in various sectors, the materiais can be used for the manufacture of household goods, building materiais and even coating of spacecraft. In the manufacture of bricks (for example, the conformation and / or drying) may cause damage to structural cracks, distortion and warping that diminish the quality of the final product. Drying is a thermodynamic process, which is reducing the moisture content of the solid, by providing energy to it. Through the study of computer simulations can predict the behavior of variables such as moisture, temperature and stress inside the bricks, you can get a drying process faster and optimized, avoiding wastage of raw materiais and fuel economy. Seeking improvements to the drying process of clay bricks, this paper presents a numerical and experimental study of the drying process of a hollow brick. A three-dimensional transient mathematical model is presented to predict the mass transfer and heat to simulate the distribution of moisture content, temperature inside the solid, considering the symmetry around the center of the solid, constant thermophysical properties and volume change (shrinkage). For validation of the numerical experiments were carried out with drying hollow bricks industrial donated by eight holes "Cerâmica Cincera", located in Santa Rita-PB. In the experiments, were used drying temperatures of 50, 60, 70, 80, 90 and 100°C. It was found that for temperaturas of 50 and 60°C and relative humidity of 20,8% and 13,5% respectively the drying rate is lower, reducing the risks of product defects. Already at the drying temperatures of 80,90 and 100°C, there are high gradients of temperature and humidity inside the brick tensionally thermal water, causing large cracks and broken, especially in the corners and the inner walls of the holes especially in the initial process, apparently reducing the processing time because thecon tractions of the outer layer and above.

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