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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.
31

Avaliação em túnel de vento do comportamento da camada limite atmosférica em terrenos complexos

Mattuella, Jussara Maria Leite January 2012 (has links)
A estrutura do vento varia de acordo com as características do terreno e com a rugosidade da superfície terrestre, desacelerando proporcionalmente sua intensidade de acordo com a proximidade do solo, o que determina a constituição da camada limite atmosférica (C.L.A.). As características do escoamento sobre e no entorno de características topográficas obtusas tais como morros são de grande interesse em muitas aplicações, especialmente aquelas ligadas à engenharia de vento. Esta pesquisa foca a investigação da C.L.A. sobre terrenos complexos, analisando a estrutura do escoamento turbulento, a separação e a recomposição do mesmo. Para tanto, dois métodos são empregados e comparados na presente investigação para identificar a influência da orografia complexa sobre o escoamento do vento: padrões ou códigos de carga de vento e análises experimentais em túnel de vento. Nove modelos experimentais de morros isolados, sendo quatro simétricos bidimensionais, quatro simétricos tridimensionais e um assimétrico, todos com a consideração de dois tipos de terreno, categoria I – plano e categorias III-IV – medianamente rugosas são analisados. A partir de uma simulação experimental da camada limite em túnel de vento, é possível parametrizar os efeitos do vento sobre terrenos complexos (MILLER, 1995). A definição de variáveis, tais como: o perfil de velocidade do vento, a intensidade de turbulência, os efeitos topográficos na velocidade do vento constituem-se em elementos fundamentais para cálculos estruturais de edificações situadas no entorno. Foram desenvolvidas simulações experimentais no túnel de vento de camada limite Prof. Joaquim Blessmann, da Universidade Federal do Rio Grande do Sul. Na superfície do modelo assimétrico, na radial principal do mesmo, foram localizados nove perfis de medição, contendo cada um, vinte alturas de investigação. Os demais modelos tiveram como foco de análise o cume dos mesmos, também com perfis definidos nas mesmas alturas. As medições da velocidade do vento e da intensidade da turbulência foram procedidas por um sistema de anemometria de fio quente. Os dados obtidos em túnel de vento foram confrontados com expressões empíricas calculadas para os mesmos pontos segundo cinco códigos ou padrões de carga de vento, pontuando também as correlações entre os mesmos e entre estes com a norma brasileira NBR 6123 (1988). Os modelos, códigos ou padrões analisados foram: Jackson e Hunt (1975) e Davenport, Surry e Lemelin (1988), models e as normas a seguir nominadas:Norma Brasileira: cargas de vento em Edificações - NBR 6123 (1988); European Standard:Eurocode1: Basis of Design and Actions on Structures, CEN TC 250: 2002; Australian/New Zealand Standard: Minimum Design Loads on Structures, AS/NZS 1170.2: 2002; Architectural Institute of Japan AIJ: 2004; American Society of Civil Engineering Standard, ASCE 7-95 (ASCE 7-95), Minimum Design Loads for Buildings and Other Structures;National Building Code of Canada, 2005, (NRCC 2005). Além do estudo comparativo acerca da resposta estimada pelos códigos nominados, esta pesquisa constitui-se em um banco de dados de medições em pontos localizados nos morros nominados, em túnel de vento. O comparativo entre os padrões mostra a inexistência de uma harmonização entre os mesmos para a consideração dos parâmetros a serem empregues para o cálculo de cargas de vento. Estas diferenças na definição dos parâmetros básicos para o carregamento de vento em estruturas determinam grandes dificuldades na unificação de formatos recomendados na previsão das cargas de vento. Comparativamente aos dados experimentais, os padrões, em geral, mostram-se conservadores para os dois tipos de morros analisados, simétrico e assimétrico, para os dois tipos de terreno, tanto considerando-se análises em 2D ou 3D. / The structure of the wind varies with the characteristics of the terrain and roughness land surface, slowing its intensity proportionally according to the surrounding terrain, which determines the onset of boundary layer (ABL). The characteristics of the flow over and around topographic features such as hills are of great interest in many applications, especially those related to wind engineering. From an experimental simulation of the boundary layer wind tunnel, it is possible to parameterize the effects of wind over complex terrain (MILLER, 1995). The definition of variables, such as the profile of wind speed, the turbulence intensity, the topographic effects on wind speed are key elements in structural calculations for buildings situated around the area. This research focuses on the investigation of the ABL complex terrain conditions, analyzing the structure of turbulent flow and characterization of separation and reattachment of the flow. Experimental simulations were developed in the wind tunnel of the atmospheric boundary layer Prof. Joaquim Blessmann, Federal University of Rio Grande do Sul in nine models of hills, four symmetrical two-dimensional, four- symmetrical threedimensional and one asymmetrical, all considering two types of terrain, category I - plan and Category III-IV- moderately rough. The surface of the asymmetric model was measured in nine profiles ploted on the main radial of the hill, with twenty heights each, and the other models were examined at top of the hill. The measurements were performed with a system of hot wire anemometry to measure the wind velocity and intensity of turbulence. The identification of the data obtained in the wind tunnel were confronted with empirical expressions for the same points, in order to establish the correlations between patterns and among these with NBR 6123 (1988). Two models and five codes of wind loads are analyzed: Jackson and Hunt (1975) and e Davenport, Surry e Lemelin (1988) Models and Brazilian Association of Technical Standards: Wind Load on Buildings, NBR 6123 (1988); European Standard: Eurocode1: Basis of Design and Actions on Structures, CEN TC 250: 2002; Australian/New Zealand Standard: Minimum Design Loads on Structures, AS/NZS 1170.2: 2002; Architectural Institute of Japan AIJ: 2004; American Society of Civil Engineering Standard, ASCE 7-95 (ASCE 7-95), Minimum Design Loads for Buildings and Other Structures; National Building Code of Canada, 2005, (NRCC 2005) codes. This study focuses not only the comparison of the response estimated by international codes nominees, but also a data bank of wind tunnel data to validate this tool based on empirical expressions. The comparison of the patterns shows a lack of consideration for international harmonization of the parameters to be employed for the calculations of wind loads. These differences in defining the basic parameters for the wind loading on structures determines difficulties to unify the formats recommended in the prediction of wind loads. Compared to the experimental data, the patterns will generally show up conservative for both types of mounts analyzed, symmetrical and asymmetrical, for both types of terrain, both considering 2D or 3D.
32

Avaliação em túnel de vento do comportamento da camada limite atmosférica em terrenos complexos

Mattuella, Jussara Maria Leite January 2012 (has links)
A estrutura do vento varia de acordo com as características do terreno e com a rugosidade da superfície terrestre, desacelerando proporcionalmente sua intensidade de acordo com a proximidade do solo, o que determina a constituição da camada limite atmosférica (C.L.A.). As características do escoamento sobre e no entorno de características topográficas obtusas tais como morros são de grande interesse em muitas aplicações, especialmente aquelas ligadas à engenharia de vento. Esta pesquisa foca a investigação da C.L.A. sobre terrenos complexos, analisando a estrutura do escoamento turbulento, a separação e a recomposição do mesmo. Para tanto, dois métodos são empregados e comparados na presente investigação para identificar a influência da orografia complexa sobre o escoamento do vento: padrões ou códigos de carga de vento e análises experimentais em túnel de vento. Nove modelos experimentais de morros isolados, sendo quatro simétricos bidimensionais, quatro simétricos tridimensionais e um assimétrico, todos com a consideração de dois tipos de terreno, categoria I – plano e categorias III-IV – medianamente rugosas são analisados. A partir de uma simulação experimental da camada limite em túnel de vento, é possível parametrizar os efeitos do vento sobre terrenos complexos (MILLER, 1995). A definição de variáveis, tais como: o perfil de velocidade do vento, a intensidade de turbulência, os efeitos topográficos na velocidade do vento constituem-se em elementos fundamentais para cálculos estruturais de edificações situadas no entorno. Foram desenvolvidas simulações experimentais no túnel de vento de camada limite Prof. Joaquim Blessmann, da Universidade Federal do Rio Grande do Sul. Na superfície do modelo assimétrico, na radial principal do mesmo, foram localizados nove perfis de medição, contendo cada um, vinte alturas de investigação. Os demais modelos tiveram como foco de análise o cume dos mesmos, também com perfis definidos nas mesmas alturas. As medições da velocidade do vento e da intensidade da turbulência foram procedidas por um sistema de anemometria de fio quente. Os dados obtidos em túnel de vento foram confrontados com expressões empíricas calculadas para os mesmos pontos segundo cinco códigos ou padrões de carga de vento, pontuando também as correlações entre os mesmos e entre estes com a norma brasileira NBR 6123 (1988). Os modelos, códigos ou padrões analisados foram: Jackson e Hunt (1975) e Davenport, Surry e Lemelin (1988), models e as normas a seguir nominadas:Norma Brasileira: cargas de vento em Edificações - NBR 6123 (1988); European Standard:Eurocode1: Basis of Design and Actions on Structures, CEN TC 250: 2002; Australian/New Zealand Standard: Minimum Design Loads on Structures, AS/NZS 1170.2: 2002; Architectural Institute of Japan AIJ: 2004; American Society of Civil Engineering Standard, ASCE 7-95 (ASCE 7-95), Minimum Design Loads for Buildings and Other Structures;National Building Code of Canada, 2005, (NRCC 2005). Além do estudo comparativo acerca da resposta estimada pelos códigos nominados, esta pesquisa constitui-se em um banco de dados de medições em pontos localizados nos morros nominados, em túnel de vento. O comparativo entre os padrões mostra a inexistência de uma harmonização entre os mesmos para a consideração dos parâmetros a serem empregues para o cálculo de cargas de vento. Estas diferenças na definição dos parâmetros básicos para o carregamento de vento em estruturas determinam grandes dificuldades na unificação de formatos recomendados na previsão das cargas de vento. Comparativamente aos dados experimentais, os padrões, em geral, mostram-se conservadores para os dois tipos de morros analisados, simétrico e assimétrico, para os dois tipos de terreno, tanto considerando-se análises em 2D ou 3D. / The structure of the wind varies with the characteristics of the terrain and roughness land surface, slowing its intensity proportionally according to the surrounding terrain, which determines the onset of boundary layer (ABL). The characteristics of the flow over and around topographic features such as hills are of great interest in many applications, especially those related to wind engineering. From an experimental simulation of the boundary layer wind tunnel, it is possible to parameterize the effects of wind over complex terrain (MILLER, 1995). The definition of variables, such as the profile of wind speed, the turbulence intensity, the topographic effects on wind speed are key elements in structural calculations for buildings situated around the area. This research focuses on the investigation of the ABL complex terrain conditions, analyzing the structure of turbulent flow and characterization of separation and reattachment of the flow. Experimental simulations were developed in the wind tunnel of the atmospheric boundary layer Prof. Joaquim Blessmann, Federal University of Rio Grande do Sul in nine models of hills, four symmetrical two-dimensional, four- symmetrical threedimensional and one asymmetrical, all considering two types of terrain, category I - plan and Category III-IV- moderately rough. The surface of the asymmetric model was measured in nine profiles ploted on the main radial of the hill, with twenty heights each, and the other models were examined at top of the hill. The measurements were performed with a system of hot wire anemometry to measure the wind velocity and intensity of turbulence. The identification of the data obtained in the wind tunnel were confronted with empirical expressions for the same points, in order to establish the correlations between patterns and among these with NBR 6123 (1988). Two models and five codes of wind loads are analyzed: Jackson and Hunt (1975) and e Davenport, Surry e Lemelin (1988) Models and Brazilian Association of Technical Standards: Wind Load on Buildings, NBR 6123 (1988); European Standard: Eurocode1: Basis of Design and Actions on Structures, CEN TC 250: 2002; Australian/New Zealand Standard: Minimum Design Loads on Structures, AS/NZS 1170.2: 2002; Architectural Institute of Japan AIJ: 2004; American Society of Civil Engineering Standard, ASCE 7-95 (ASCE 7-95), Minimum Design Loads for Buildings and Other Structures; National Building Code of Canada, 2005, (NRCC 2005) codes. This study focuses not only the comparison of the response estimated by international codes nominees, but also a data bank of wind tunnel data to validate this tool based on empirical expressions. The comparison of the patterns shows a lack of consideration for international harmonization of the parameters to be employed for the calculations of wind loads. These differences in defining the basic parameters for the wind loading on structures determines difficulties to unify the formats recommended in the prediction of wind loads. Compared to the experimental data, the patterns will generally show up conservative for both types of mounts analyzed, symmetrical and asymmetrical, for both types of terrain, both considering 2D or 3D.
33

Dynamisk dimensionering av hög träbyggnad med horisontalstabiliserande kärna av KL-trä och prefabricerade volymelement / Dynamic design of high-rise timber building with horizontally stabilising CLT core and prefabricated volume elements

Lindberg, Albin January 2018 (has links)
Efterfrågan på höga byggnader ökar i städerna och eftersom hållbarhet är ett viktigt ämne i samhället har intresset för och användandet av trä i höga byggnader ökat de senaste åren. Träbyggnaders flexibilitet och låga vikt gör att svängningar orsakade av horisontella dynamiska vindlaster i bruksgränstillståndet kan uppfattas som störande av personer som vistas i byggnaden och därav bli styrande för dimensioneringen av byggnaden. I detta examensarbete studeras en hybridlösning som använder sig av en vertikalt bärande och horisontellt stabiliserande kärna av KL-trä samt byggs upp med lätta prefabricerade volymelement. Syftet med arbetet är att ta fram en lämplig uppbyggnad och studera dess dynamiska egenskaper samt studera hur förändringar av kärnans parametrar och uppbyggnad påverkar de dynamiska egenskaperna. Målet är att erhålla svar på maximalt antal våningar för respektive alternativ uppbyggnad samt utöka förståelsen på kärnans inverkan på byggnadens dynamiska respons. Byggnaden modelleras upp enligt fyra olika huvudstrukturer där Struktur 1 är byggnadens grundmodell enligt dess enklaste uppbyggnad, inom Struktur 2 varierar KL-träkärnans väggtjocklek, inom Struktur 3 varierar KL-träkärnans storlek och inom Struktur 4 adderas horisontalstabiliserande väggar till KL-träkärnan. I alla modeller antas volymelementen ej bidra till byggnadens globala stabilitet och därför modelleras de in som massor. De olika strukturerna modelleras upp i FEM-programvaran Robot Structural Analysis där en modalanalys utförs för att erhålla byggnadens egenfrekvenser och svängningsmoder. Därefter beräknas toppaccelerationen hos svängningarna, orsakade av dynamisk vind, på golvbjälklaget i byggnadens översta våning ut för hand för att jämföras mot komfortkrav i ISO 10137. Resultaten visar att byggnaden generellt sett har låga egenfrekvenser vilket beror på en förhållandevis hög massa och relativt låg styvhet hos strukturen. Struktur kan uppföras till 20 våningar under de förhållanden som använts i beräkningarna. Förändringar i kärnans tjocklek förstyvar byggnaden något vilket gör att Struktur 2 bör kunna uppföras ett par våningar högre. Förändringar i kärnans storlek visar sig ha en relativt stor påverkan på byggnadens styvhet och därför kan Struktur 3 uppföras till 24 våningar då kärnan är 25 % större i alla riktningar. För Struktur 1, 2 och 3 sker svängning först i y-led, sedan i x-led och sist som vridning kring z-axeln. För Struktur 4 visar sig styvheten påverkas mycket av att stabiliserande väggar adderas till kärnan, dock kan även svängningsriktningar för första och andra svängningsmod förändras och det bör kontrolleras så att problem med vridningssvängningar inte uppkommer. Om stabiliserande väggar läggs till i y-riktning, x-riktning samt del av fasad kan Struktur 4 uppföras hela 28 våningar, med förhållandevis god marginal. Som förslag på fortsatt arbete bör en statisk dimensionering utföras för att vidare utreda om uppbyggnaden är lämplig vad gäller bland annat tvärsnittstorlekar och infästningar. Dessutom bör det undersökas om och hur volymelementens styvhet kan användas för att bidra till strukturens globala stabilitet. Då kärnans storlek har en stor påverkan på byggnadens styvhet bör det utredas ifall lämpliga planlösningar kan arbetas fram med större eller till och med dubbel kärna för att sedan utföra en dynamisk dimensionering på strukturen. Då planlösningen enligt denna och andra studier bedöms ha potential för att bygga högt, vore en jämförelse av olika planlösningar intressant där förslagsvis byggnadens yttermått och form samt placering och antal stabiliserande KL-träkärnor varierar. / The demand on high-rise buildings grows in the cities and since sustainability is an important matter in today’s society, the interest for high-rise timber buildings has grown the past years. The flexibility and weight of timber buildings makes wind-induced vibrations in serviceability limit state an issue that can be deciding for the design of the building since people can find the vibrations disturbing. In this study, a building which uses a vertically load-bearing and horizontally stabilising CLT core and is built-up with light prefabricated volume elements. The objective of this study is to produce a suitable structure and study its dynamic properties and how changes of the core’s parameters and design may change the dynamic properties of the building. The goal is to find the maximum number of floors that can be built for each alternative structure and to expand the knowledge on how the CLT core impacts the dynamic response of the building. The building is modelled by four different main structures where Structure 1 is the building’s basic and most simple model, within Structure 2 the CLT core’s wall thickness varies, within Structure 3 the CLT core’s size varies and within Structure 4 horizontally stabilising walls are added to the core. In all of the models, the volume elements are assumed not to contribute to the global horizontal stability of the building which is why they are modelled as masses. The different structures are modelled into the FEM software Robot Structural Analysis where a modal analysis is being carried out to find the building’s natural eigenfrequencies and modes of vibrations. Subsequently, the top acceleration of the wind-induced vibrations is calculated on the floor slab of the top floor by hand to be compared to comfort limits in ISO 10137. The results show that the building has low eigenfrequencies in general, which is due to the structure’s relatively high mass and low stiffness. Structure 1 can be built up to 20 floors under the conditions used in the calculations. Changes of the core’s wall thickness stiffen the building which means that Structure 2 should be able to build a couple of floors higher. Changes in the size of the core have a relatively large impact on the rigidity of the building and therefore Structure 3 can be built up to 24 floors when the core is 25 % larger in all directions. For Structure 1, 2 and 3, swaying occurs first in the y-direction, second in the x-direction and third as twist around the z-axis. For Structure 4, the rigidity is greatly influenced when stabilising walls are added to the core. However, the direction of the first and second modes of vibration can change and it should be verified that problems with twisting oscillation does not occur. If stabilising walls are added in the y-direction, x-direction and part of the façade, Structure 4 can be built up to 28 floors with a relatively good margin. As a proposal for further work, a static design should be performed to further investigate whether the structure is suitable for e.g. cross-sectional sizes and connections. It should also be examined if and how the rigidity of the volumes can be used to contribute to the global stability of the structure. As the size of the core has a major impact on the rigidity of the building, it should be investigated if a suitable floor layout can be arranged with larger or even double cores and then perform a dynamic design on the structure. As the floor layout, according to this and other studies, is considered to have great potential when building high, a comparison of different floor plans would be interesting where e.g. the external dimensions and shape of the building, as well as the placement of the CLT core and number of cores can vary.
34

Analýza přídržnosti hydroizolačních systémů ze samolepicích asfaltových pásů / Analysis of adhesion of waterproofing systems of self-adhesive asphalt felts

Kerekanič, Robin January 2018 (has links)
This diploma thesis focuses on the adhesive of asphalt felts on flat roofs. The practical part evaluates on the basis of experiments the adhesion of self-adhesive asphalt felts on conventional system with warm deck. It proposes and experimentally verifies the method for temperature cycling of samples and the system for causing condensation under bitumen sheet. The influence of temperature and humidity on the adhesion of the bitumen sheet during the realization, the subsequent effects of these influences as well as the condensation test are monitored by static loading. The influence of the dynamic load on the adhesion of the waterproofing to expanded foamed polystyrene is also tested. In the discussion and conclusion, the influence of the human factor on the resulting adhesion and the suitability of the methods used are also assessed.
35

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.
36

Zastřešení atletické haly / Roofing of Athletic Hall

Potůčková, Simona Unknown Date (has links)
The aim of this diploma thesis is a design of two versions of bearing roof construction of the athletic stadium in Brno and a smaller side roofing of changing rooms. The building has rectangular plan of dimension 67 x 102 m and the side construction has also rectangular plan of dimension 61x 8 m. The minimum height is given by requirements of various athletic sports. Material used for the main construction is steel strength class S355 and for the side construction it is steel strength class S235. All the calculations are according to valid norms ČSN EN.
37

Dynamická analýza válcových komínů stojících za sebou / Dynamic analysis of an in-line arranged cylindrical chimney

Harazim, Petr January 2013 (has links)
The diploma thesis deals with the response of a steel smokestack structure to wind loads. A detailed computational model implementing the finite element method was created in accordance with the available drawing documentation. The new smokestack was placed next to an existing one, thus it can be assumed that these two structures will affect each other. The thesis also elaborates on the problems of aerodynamic and aeroelastic stability of the earlier smokestack; in particular, the occurrence of vortex shedding in resonance with eigenfrequency of the structure, with the use of the program ANSYS CFX. The evaluation of the structure includes survey of the strength and deflections of the structure. The calculations are in accordance with valid ČSN EN norms.
38

Zatížení větrem na chladící věž / Wind load on cooling tower

Ehrlich, Tomáš January 2015 (has links)
Thesis is concerned with modeling fluid dynamics and computing wind load on thin-walled structure of cooling tower. Two models for computational fluid dynamics are presented – one with singleton cooling tower and second with group of four cooling tower. Thesis includes also a structural model of cooling tower and methodology of wind load transfer is presented.
39

Nosná ocelová konstrukce rozhledny / Steel Structure of Observation Tower

Virág, Patrik January 2016 (has links)
The subject of the diploma thesis is design and structural analysis of loadbearing steel structure of observation tower, which is located southeast of Černá Hora, township Blansko. The design is processed in two options. Parts of the thesis are engineering report, structural design report for both of the options and graphical documentation in specified range. The structure’s height is 25.3 m and maximal ground plan dimension is 6 x 6 m. Steel grade S355 was chosen as main material. The sub-objectives of the structural analysis are load effects calculations (permanent load, imposed load and climatic load), entering of loads to the calculation model and calculation of internal forces and deformations. An assessment of the supporting elements and selected joints is also included. There are dynamic design features considered in the calculation. All calculations were performed in accordance with valid ČSN EN standards.
40

Posouzení mostní konstrukce na účinky dynamického zatížení / An assessment of a bridge construction on a dynamic load

Součková, Markéta January 2017 (has links)
Diploma thesis deas with static and dynamic analysis of a steel arch footbridge. The footbridge structure 3D model was created in program ANSYS 12.1 and afterwards were made static and modal analysis on this computational model. Based on the results of~modal analysis was applied to design of dynamic wind loading on the model according to norms ČSN EN. The effects of this burden has been calculated steady response at resonance from harmonic analysis according to ČSN P EN 1991-2-4. To report according to ČSN EN 1991-1-4 was designed substitute quasistatic forces corresponding loads of wind on the construction and for evaluation was used static analysis.

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