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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

[en] CONSTRUCTION AND MECHANICAL BEHAVIOR OF A TENSEGRITY PEDESTRIAN BRIDGE BUILT WITH NATURAL MATERIALS / [pt] CONSTRUÇÃO E COMPORTAMENTO MECÂNICO DE UM MÓDULO DE PONTE TENSÉGRITA UTILIZANDO MATERIAIS NATURAIS

NATHALIA BURGER DE ALBUQUERQUE 14 December 2020 (has links)
[pt] Neste trabalho, apresenta-se um estudo numérico e experimental sobre o comportamento estrutural de um módulo de ponte tensegrity para pedestres com materiais naturais. Inicialmente é apresentado o conceito de estruturas tensegrity, destacando-se seu surgimento e atual contexto, aplicações e estudos relacionados a este sistema estrutural. Também é apresentada a importância e os benefícios da utlização de materiais naturais na construção civil. Um projeto de ponte tensegrity para pedestres realizado previamente é selecionado como objeto de estudo. Com base em suas principais características, realiza-se um protótipo do módulo da ponte em escala 1:25. Propõe-se um método construtivo considerando técnicas ajustáveis para montagem e desmontagem. Posteriormente, um protótipo em escala de aproximadamente 1:6 é construído utilizando colmos de bambu da família Phyllostachys aurea para as estroncas e cordas de sisal para os cabos. O módulo é instrumentado e ensaiado estatica e dinamicamente a fim de avaliar a influência das perdas de pretensão por fluência e relaxação sobre o comportamento da estrutura. Os resultados obtidos dos ensaios experimentais são comparados com as previsões numéricas obtidas com auxílio de modelo computacional quanto às tensões atuantes e os modos de vibração. Através do cruzamento dos dados foi possível determinar indiretamente o nível de pretensão aplicado no módulo tensegrity e avaliar a perda de pretensão ao longo do tempo. As investigações estática e dinâmica apresentaram considerável afinidade. / [en] In this work, a theoretical and practical study of the behavior of a tensegrity based pedestrian bridge constructed with natural materials is presented. Initially it is shown the concept of tensegrity structures, highlighting its emergence and current context, applications within civil engineering and studies related to this structural system. The importance and benefits of using natural materials in civil construction are also presented. A pedestrian bridge design made using tensegrity structure is designated as study object and a prototype of the bridge s module is built in 1:25 scale. A constructive method is proposed considering deployable techniques for assembly and disassembly. Subsequently, a prototype on a 1: 6 scale is built using Phyllostachys aurea bamboo culms for the struts and sisal ropes for the cables. The module is instrumented and tested statically and dynamically in order to understand the processes of loss of prestress and creep on the structure s behavior. The results obtained from the experimental tests are compared with the numerical predictions obtained with the aid of a computational model regarding the stresses and the vibration modes. Through the crossing of the data it was possible to indirectly determine the level of prestress applied in the tensegrity module and to evaluate the loss of prestress over time. The static and dynamic investigations showed considerable affinity.
2

Massivträ : Jämförelse mellan olika principer för sammanfogning av trä till plattelement med avseende på pris, hållfasthet och ekologi / Solid Wood Systems : Comparison of different principles to combine timber to solid wood boards in consideration of cost, sustainability and ecology

Buck, Dietrich January 2013 (has links)
Ökad användning av byggtekniken massivträ kan ge ett positivt bidrag till hållbart byggande. Utvecklingen inom datornavigerad bearbetning ger massivträ möjligheten att rationalisera byggproduktionen inom trä. Tekniken ligger rätt i tiden och kommer att värderas allt högre då den tillvaratar materialets karaktäristiska egenskaper. Utvecklingen av massivträ har resulterat i teknikvarianter av hur virke kan sammanfogas till solida element. Ett behov har funnits av en marknadsjämförelse mellan befintliga principer där studien förtydligar grundläggande skillnader för intresserade byggaktörer. Problemfrågan för denna studie har varit: vilka principer för sammanfogning av trä till plattelement inom massivträ är mest fördelaktiga? Detta sett utifrån faktorerna produktionskostnad, hållfasthet och ekologiska övervägningar. För att förtydliga den undersökta byggmetodens nytta i ett vidare perspektiv har det presenterats en allmän beskrivning av massivträ. Studien är jämförande och grundar sig på en litteraturstudie samt företagskontakter med 27 företag i 6 länder. Följande tekniker för tillverkning av plattelement i massivträ har behandlats i rapporten:  Limning  Spikning  Klamring  Skruvning  Tvärspänning  Dymling: vertikal-, horisontal- och diagonalgående samt med skruvar i trä  Laskning  Träsvetsning Studien visar att teknikerna inom massivträ skiljer sig åt. Högst bedömning får korslimmat trä (CLT) när det gäller kostnad och hållfasthet. Med hänsyn till ekologin värderas laskat trä högst. Vid en sammanvägning av hållfasthet och ekologi är den skruvformade trädymlingen fördelaktigast. Dessa alternativ ger valfrihet i synlig yta samt ett effektivt resursutnyttjande av lågvärdigare virkeskvalitéer och lämpar sig inom bostadsbyggnation. CLT är mest kostnadseffektivt, inte patentskyddat samt det mest etablerade alternativet på marknaden dock är utvecklingen av ett sunt lim fortfarande under arbete. I pågående forskning finns ett annat alternativ där tekniken träsvetsning visat ge en starkare fog än lim. Ur ekologisk synpunkt är plattelement genomgående i trä är att föredra, då det ger en sund konstruktion i full skala, eftersom inga kemikalier eller lagerresurser används. Forskning har visat att massivträ har en positiv och hälsofrämjande effekt på de boende i motsats till effekterna av icke naturliga material. / The increasing use of solid wood construction methods can have a positive impact on the sustainability of constructions. The development of computer-controlled processing techniques enables the solid wood timber industry to rationalize the construction of buildings. The solid wood techniques come at time and will be higher valued in the future due to the natural characteristics of this material. The improvement of solid wood methods has resulted in various techniques to join wood into solid prefabricated parts. There is a need for a comparative market study of the different principles of solid wood construction to widen the knowledge and to explain interested builders the viability of these techniques. The key question for this study is: Which techniques of combining solid wood elements to whole boards are the most favorable ones concerning wood construction buildings – leaving apart questions of production costs, durability and ecological considerations? To point out the utility of these construction techniques and give them a broader understanding a general study of solid wood construction has been presented. The comparative study is based as well on studies of literature as on reviews of 27 companies in 6 countries. The following techniques for the production of boards made of solid timber elements are considered in this report:  Laminating  Nailing  Stapling  Screwing  Stress laminating  Doweling: vertically, horizontally, diagonally and with wooden screws  Dovetailing techniques  Wood welding techniques The study shows that the techniques of solid wood construction are very different in itself. CLT of cross-laminated timber scores highest in terms of cost and durability, but if one considers ecological factors, dovetailing is best. Taking into account both durability and ecological considerations, doweling is best. These alternatives give some freedom of choice regarding the visibility of surfaces and the efficient use of lower qualities of timber and they are therefore suitable for residential construction buildings. CLT is the most cost-effective, not patented and well established option in the market; the development of more health-friendly adhesives is still going on. Current researches demonstrate an alternative: Wood welding joins the parts better together than gluing them. Considered from the ecological viewpoint, boards made exclusively of wood, are preferable since no chemicals or not renewable resources are used. Recent researches show, that solid wood constructions have positive effects on the health of the residents of these buildings in comparison of buildings using non-natural materials. / <p>ORCID-id: 0000-0001-7091-6696</p>
3

Obytný areál Ponavia park v Brně, příprava a organizace stavby / Preparation and Organization of Construction

Hladký, Dominik January 2020 (has links)
This thesis deals with the construction process of the apartment house Ponavia Park located in Brno. The thesis solves the individual realization phases of the main building phase. Building site equipment is designed for the projected construction process in three different variations. A technical report is also included in the building site. Critical points within the transport of materials and machines are also verified. A financial plan for the whole building is made as an summarizing time schedule for the apartment building. The sources for the financial plan are the figures taken from the Czech building objects classifications (JKSO). The summarizing time schedule is made in MS Projekt software and it’s designed as a Gantt diagram. A design of the main building machines and mechanisms was also made for the projected construction process. All of the machines were assessed for their respective required function on the building site. Also included in this thesis is a construction method for the reinforced concrete structures. The construction method deals with the realization process of waterproof concrete, reinforcement binding, formwork of the vertical and horizontal structures and also the process of concrete curing. The construction method is followed up by quality control and test plans for reinforced concrete structures, and a construction site safety plan that is made in the form of predicted main safety risks at the building site. For the noise load on the surrounding buildings a noise study is made. The study examines the intensity of noise in the protected outdoor space. This study was made in the Hluk+ software. The thesis also includes an item budget for the apartment house that was made in Build Power S software.

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