• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 84
  • 23
  • 11
  • 10
  • 8
  • 8
  • 3
  • 2
  • 2
  • 2
  • Tagged with
  • 158
  • 158
  • 61
  • 56
  • 56
  • 47
  • 43
  • 42
  • 38
  • 31
  • 24
  • 23
  • 22
  • 21
  • 20
  • 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.
51

Edifícios com lajes maciças e paredes portantes pré-moldadas de concreto leve com pérolas de EPS / Buildings with solid slabs and load bearing precast walls of lightweight concrete with EPS beads

Diego de Vasconcelos Gonçalves Ferreira 28 May 2013 (has links)
Atualmente, muitas empresas de construção civil não acompanham o avanço tecnológico, preferindo utilizar sistemas convencionais em vez de investir em novas soluções. Além disso, há sérios problemas com mão de obra, que estão cada vez mais presentes na sociedade. Este trabalho apresenta o projeto de um edifício com elementos pré-moldados de Concreto Leve com pérolas de EPS, considerando lajes prontas maciças e paredes portantes, executadas com esse tipo de material. A princípio, foram considerados os estados limites últimos e de serviço para os elementos da estrutura, utilizando os modelos clássicos de análise estrutural. Para modelagem do edifício, foi utilizado o programa comercial SAP2000. Quanto aos procedimentos para dimensionamento das peças, foram preparadas planilhas do Excel, enquanto o detalhamento foi realizado por meio do AutoCAD. Definido o projeto estrutural, foram considerados aspectos construtivos na fábrica e na obra, levando em conta os custos de produção e de transporte, além de apresentar as vantagens que esse sistema construtivo pode proporcionar. Esses custos foram considerados para as lajes prontas maciças e para as paredes pré-moldadas. Mesmo levando em conta apenas os custos de produção e de transporte, o Concreto Leve com EPS foi comparado com o Concreto Autoadensável, o que permitiu visualizar as vantagens do primeiro, quando for considerado o custo global do empreendimento. / Currently, many construction companies do not follow the technological advances, preferring to use conventional systems rather than investing in new solutions. Moreover, there are serious problems with manpower, which are increasingly present in society. This work presents the design of a building with precast elements of lightweight concrete with EPS beads, considering solid slabs ready to use and load bearing walls, made with this type of material. As a rule, the ultimate limit states and serviceability were considered for the elements of the structure, using classical models of structural analysis. For modelling the building, the commercial software SAP2000 was used. Regarding the procedures for dimensioning of the pieces, Excel spreadsheets were prepared, while the detailing was carried out by means of the AutoCAD. Defined structural design, construction aspects were considered in the factory and in the work, taking into account costs of production and transportation, besides presenting the advantages that this constructive system can provide. These costs were considered for the solid slabs ready to use and for the precast walls. Even taking into account only the cost of production and transportation, the Lightweight Concrete with EPS was compared with Self-compacting Concrete, allowing visualize the advantages of the former when considering the overall cost of the project.
52

Characterisation and performance of fibre-reinforced composite restorations

Al-Haddad, Ala'A. January 2015 (has links)
In the modern era of metal-free minimally-invasive dentistry, there is a growing tendency toward using metal-free restorative alternatives that provide not only excellent aesthetics but also enable superior durability. Fibre-reinforced composite (FRC) is one cost-effective alternative that fulfils the requirements of aesthetics and durability, and offers favourable physico-mechanical properties. Many FRC applications are well-documented in the literature, such as crowns and fixed partial dentures (FPD); however, their clinical implementation is still limited, owing to the lack of significant knowledge about their longevity, deterioration signs, optimum design and overall performance. This in-vitro research aimed to address these uncertainties by investigating the performance of FRC restorations, and the influence of fibre reinforcement on particular physcio-mechanical properties, including surface hardness, edge-strength, shear bond strength, fatigue and wear resistance. Basic testing models were used to investigate the effect of incorporating differently-oriented FRCs on the surface hardness, edge-strength and shear bond strength of particulate-reinforced composite (PRC). The results revealed that the incorporation of FRC significantly enhanced surface hardness (by 12 - 19 %) and edge-strength (by 27 -75 %). However, this incorporation significantly reduced the shear bond strength (SBS) between PRC and other restorative materials, including lithium disilicate ceramic (10.9±3.1 MPa) and Co-Cr metal alloy (12.8±2.3 MPa), compared to the control (15.2±3.6 MPa, 15.0±3.7 MPa). The orientation of FRC was also found to affect the efficiency of reinforcement as bidirectional FRCs exhibited significantly higher hardness (76.8±1.2 VHN), edge-strength (67.7±8.2 N) and SBS (14.1±3.9 MPa) values than unidirectional FRCs (72.4±1.2 VHN, 56.8±5.9 N, 9.8±2.3 MPa).Clinically-relevant testing models, employing accelerated aging techniques, were performed to investigate the fatigue and wear behaviours of anatomically-shaped FRC restorations in-vitro. Direct inlay-retained FRC-FPDs with two framework designs, were tested for their fatigue behaviour and load-bearing capacity. Type-I design (with an additional bidirectional FRC layer incorporated perpendicular to the loading direction) yielded significantly higher fatigue resistance (1144.0±270.9 N) and load-bearing capacity (1598.6±361.8) than Type-II design (with a woven FRC embedded around the pontic core) (716.6±72.1 N, 1125.8±278.2 N, respectively). However, Type-19II design exhibited fewer delamination failures. Both framework design and dynamic fatigue were found to have a significant influence (p < 0.05) on the load-bearing capacity of FRC-FPDs. Additionally, the in-vitro fatigue and wear behaviours of FRC crowns, fabricated conventionally from bidirectional FRC and indirect PRC (Sinfony), were compared with those made of two CAD/CAM alternatives, namely Lava Zirconia (LZ) and Lava Ultimate (LU). A chewing simulator was employed to induce some fatigue wear in crowns, while an intraoral 3D scanner was used to quantify the resultant morphological changes. The results showed that FRC crowns had significantly lower mean cumulative wear (233.9±100.4 μm) than LU crowns (348.2±52.0 μm), but higher than LZ crowns (16.4±1.5 μm). The mean load bearing-capacity after fatigue simulation was also the highest for LZ crowns (1997.8±260.2 N) compared with FRC (1386.5±258.4 N) and LU crowns (756.5±290.9 N).Accordingly, the incorporation of FRC in resin-composite restorations is advocated since it increases surface hardness and marginal integrity, improves fatigue and wear behaviours, and enhances load-bearing capacity and overall performance.
53

Pravděpodobnostní analýza spolehlivosti a životnosti železobetonových mostů / Probabilistic reliability and durability analyses of reinforced concrete bridges

Šomodíková, Martina Unknown Date (has links)
This thesis deals with the development of a complex methodology for probabilistic analysis of reliability and durability of reinforced concrete structures, especially road bridges. An estimation of load-bearing capacity is carried out using probabilistic methods in combination with the nonlinear finite element method analysis and also with respect to reliability requirements according to standards. The current state of the structure is taken into account based on the mathematical modeling of the degradation processes, such as concrete carbonation, chloride ingress and subsequent corrosion of reinforcement. Then the load-bearing capacity and reliability is predicted over time. Attention is focused on the upgrade of the analytical models for modeling of degradation processes with regard to the effect of mechanical load on the structure or its components, the development of an artificial neural network-based response surface method for efficient approximation of the original limit state function with respect to the accuracy and a minimization the number of simulations, and an interconnection of individual processes and advanced methods in an automatic process.
54

Ocelový skelet průmyslového objektu / Steel Structure of Industrial Building

Buchta, Vojtěch January 2018 (has links)
The diploma thesis deal with design of a technological building in Ostrava serving for the sorting of slag to enagle its sequential use. Geometry of the structure was customized to technological requests. Static system was considered in two versions – joint connections with vertical bracing and omni-directional frame. For detail processing was chosen the joint one, besause it showed up as more advantageous. Static calculation was performed by Scia Engineer 14 software, then some typical connections and drawings were manually designed.
55

Jezdecká hala ve Valašském Meziříčí / The Riding Hall in Valašské Meziříčí

Rantová, Katarína January 2018 (has links)
The subject matter of this diploma thesis is a design timber structure of riding hall. The hall is a one nave building. The dimensions of ground plans is 32,0m x 70,0m and the hall is 10,0 meters high. The load-bearing structure consists of arched ribs.This timber structure composed of glued laminated timber. The building is located in Valašské Meziříčí, climate loads are designed for the area. The calculation were made in accordance with the Czech technical norms ČSN EN. The structural design and analysis is performed by software SCIA Engineer 17.
56

Autosalon / Motor show

Kopal, Marek January 2018 (has links)
By submitting my thesis I designed three variants of the steel construction of the motor show. The ground dimensions of the entire structure are 56 x 40 m. The building eaches a height of 21 m above the surrounding terrain. The object is the administrative part of the rectangular ground plan and the exhibition space of the perimeter ground plan. The circular part is a covered dome. Variants differ in design of the radial arc cross section in the dome cover. Part of the main structural elements. The winning variant includes a solution of selected details elaboration of detailed drawings of solved connections and creation of workshop documentation of the selected work.
57

Rozhledna v Brně Kohoutovicích / Watchtower in Brno Kohoutovice

Komárek, Ondřej January 2019 (has links)
The main aim of my master´s thesis was to design a load-bearing steel structure of the lookout tower situated in Brno-Kohoutovice. The height of the load-bearing structure is 35.5 m. My design comprises two different engineering solutions. Solution A is a lattice space frame whereas Solution B works with continuous columns with vertical bracing. For further development, Solution A has been chosen. The proposed structural material is the S355 steel. My thesis includes an engineering report, a statics analysis and drawing documentation.
58

Hangár / Hangar

Matějková, Pavla January 2019 (has links)
Diploma thesis contains a design of steel load-bearing structure of a hangar placed in Brno-Medlánky. The ground dimensions are 40.0×44.0 m, the height of the building is 10.0 m. Two preliminary variants of the design solution were processed; main difference is the shape of the truss girder. Both variants were assessed for a combination of seventeen load cases. The comparison of the variants led to the selection of the final variant, which was assessed in detail. The girder truss in this variant is an arched truss, the height of the truss is 1.5 m, the individual elements are made of square hollow sections. A detailed static calculation was performed including the calculation of joints, drawing documentation and technical report. The main construction material is S235JR steel.
59

Čistička odpadních vod / Sewage clarification plant

Stará, Anna January 2013 (has links)
The theme of the dissertation is structural survey of designed sewage clarification plant. The work deal about designed of reinforcement of the sewage clarification plant. The diameter of the reservoir is 17,8 m and the depth is 6,2 m.
60

Vyhlídková věž v západních Jeseníkách / The Viewing Tower in Western Jeseníky

Nosková, Denisa January 2015 (has links)
The purpose of this thesis is to create design and static assessment of the viewing tower in western Jeseníky mountains. The Ground plan is formed by regular hexagon with outer diameter 0.8 meter. Glued laminated profiles, steel tubes and elements of solid wood were predominantly used for the construction of the building. The viewing tower has four viewing platforms and total high of the structure is 28.5 meters.

Page generated in 0.083 seconds