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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.
21

Dálniční viadukt / Motorway Viaduct

Čtvrtlík, Libor January 2020 (has links)
The aim of diploma thesis was designing motorway viaduct over rowing track. From three possible options was selected one, which represents cable stayed bridge with three spans. Design procedures and assessments were pefrormed to comply with the ultimate an serviceability limit state according to valid European standards. The calculation was performed in software Midas Civil 2020. Structural assessment was done by IDEA Statica 10.1 in combination with hand-done calculation. The part of this thesis is also enclosed drawings and visualizations.
22

Vibration-based Cable Tension Estimation in Cable-Stayed Bridges

Haji Agha Mohammad Zarbaf, Seyed Ehsan 11 October 2018 (has links)
No description available.
23

A Sensor for Ice Monitoring on Bridge Superstructures

Mirto, Clinton James January 2015 (has links)
No description available.
24

Structural behaviour and stability of steel beam-column elements in under-deck cable-stayed bridge / Plieninių paspyrinių tiltų gniuždomų lenkiamų elementų įtempių deformacijų būsena ir stabilumas

Misiūnaitė, Ieva 18 March 2014 (has links)
The dissertation investigates the issues addressed to Under-Deck Cable-Stayed (UDCS) bridge, analyses its in-plain structural behavior and stability verification with an approach of Advanced Analysis. The main objects of research include effective form-finding of steel UDCS bridge, structural behaviour and stability analysis by means of beam-column elements based on the Direct Analysis Method. The study approaches a few main tasks such as a new form of UDCS bridge by accounting for the economical and efficient structural design criteria; dealing with the generalized calculation models of the additionally restrained steel beam-column elements; the development of the computational method for the direct analysis of the steel structures and especially bridges using generalized calculation models and outlining practical guidelines for UDCS bridge design. The dissertation consists of five parts including Introduction, 4 chapters, Conclusions, References and 3 Annexes. The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the study, research methodology, scientific novelty, the practical significance of results examined in the thesis and defended statements. The introduction ends in presenting the author’s publications on the subject of the defended dissertation, offering the material of made presentations in conferences and defining the structure of the dissertation. Chapter 1 revises used... [to full text] / Disertacijoje nagrinėjama paspyrinių tiltų konstrukcijų plokštuminė elgsena ir stabilumas, taikant inovatyvius analizės metodus. Pagrindinis disertacijos tikslas – atlikti naujos paspyrinės konstrukcijos paiešką ir pasiūlyti skaičiavimo metodiką ir algoritmus naujosios konstrukcijos gniuždomų lenkiamų elementų įtempių ir deformacijų analizei bei stabilumo vertinimui taikant, visuminei analizei keliamus reikalavimus. Disertacijoje taip pat siekiama pateikti metodiką paspyrinių konstrukcijų įrąžų reguliavimui. Darbe sprendžiamos kelios grupės uždavinių, kurių pirmoji skirta naujos paspyrinės konstrukcijos ir jos elgseną reikiamu tikslumu nusakančio apibendrinto gniuždomo lenkiamo elemento su tarpine paslankia atrama skaičiuojamojo modelio netiesinei elgsenos ir stabilumo analizei. Antroji siejama tu patikslintais skaičiuojamaisiais modeliais ir analizes metodais atsižvelgiant į visuminei analizei keliamus reikalavimus. Disertaciją sudaro įvadas, 4 skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai ir 3 priedai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmas skyrius skirtas literatūros... [toliau žr. visą tekstą]
25

O uso do GPS como instrumento de controle de deslocamentos dinâmicos de obras civis - aplicação na área de transportes / The use of GPS as control instrument of dynamic displacements of civil structures

Larocca, Ana Paula Camargo 25 June 2004 (has links)
Este trabalho apresenta o desenvolvimento de metodologia para avaliar a utilização do Sistema de Posicionamento Global (GPS) como ferramenta de pesquisa no estudo do comportamento dinâmico de obras viárias. Para ser caracterizado como um instrumento de medição, foi estudada a potencialidade de um método, que se fundamenta numa forma específica de coleta e processamento de dados GPS; análise dos resíduos resultantes do processamento da dupla diferença de fase e aplicação de análise espectral para filtragem de informações indesejáveis (multicaminhamento dos sinais GPS). A coleta envolve um oscilador eletro-mecânico, especialmente projetado, que permite calibrar as medidas de amplitude e freqüência das oscilações mensuráveis pela obra sob teste. Inúmeros experimentos foram realizados em ambientes de reflexões e difrações variáveis e com diversos tipos de receptores e antenas GPS. Alguns ensaios foram realizados utilizando, simultaneamente, equipamentos como transdutores de deslocamento, acelerômetros e estações totais. Comparando os resultados obtidos, mesmo com valores prescritos em normas e códigos, afirma-se que o GPS, sob o método de coleta de dados testado, é um instrumento confiável para detecção e caracterização do comportamento dinâmico de estruturas, apresentado confiabilidade para as medições realizadas, da ordem de décimos de milímetro. Quanto à detecção das freqüências, as mais baixas ficam comprometidas pela presença do multicaminhamento e as mais elevadas têm a detecção limitada pela máxima taxa de coleta dos receptores (Lei de Nyquist) / This work presents the development of a methodology to appraise the use of Global Positioning System (GPS) as a tool for researching of dynamic behavior of road transport structures. To be characterized as an instrument for measuring it was studied the potentiality of one method which includes a specific mode of GPS data collection; analyses of double difference phase residuals and application of spectral analyses and filtering for excluding undesirable information (multipath). The GPS data collected applies an electro-mechanical oscillator, specially built for that, which permits to calibrate the measures of frequency and amplitude of structure’s oscillations under dynamic load test. Several field tests were carried out in vicinities with high and low capacity of causing signal reflections and diffractions and with different types of GPS receivers and GPS antennas. A couple of fields were carried out using, at the same time, transducers of displacement, accelerometers and total stations. Comparing these results obtained even with values of codes, it is affirmed that GPS, under the data collection method tested, it is a trustworthy instrument for detection and characterization of dynamic behavior of structures, presenting reliability of measures ranging around tenths of millimeters. The very low frequencies are highly degraded by multipath and very high frequencies have its detection limited by the receiver data rate (Theorem’s Nyquist)
26

ANA-PSp: um sistema computacional para análise aeroelástica de pontes suspensas por modelos matemáticos reduzidos. / Ana-PSp: a computational system for aeroelastic analysis of suspended bridges for reduced mathematical models.

Kreis, Eri Sato 22 November 2007 (has links)
As características arquitetônicas e o desempenho estrutural de pontes suspensas, estaiadas ou pênseis, têm determinado a sua crescente utilização em obras de arte destinadas a vencer grandes vãos. Essa utilização crescente que ocorreu no mundo nas últimas décadas se repete agora nos últimos anos no país. Várias dessas obras estão em execução e em projeto. Um dos aspectos relevantes na análise estrutural das pontes suspensas é o de seu comportamento quando submetidas à ação do vento. Apresenta-se o sistema computacional ANA-PSp desenvolvido especialmente para o estudo do movimento de tabuleiros de pontes suspensas sujeitas a esforços aeroelásticos e aerodinâmicos. Esse sistema computacional formado por um conjunto de subsistemas, é elaborado para a análise aeroelástica de pontes suspensas sob a ação de vento e permite análises paramétricas extensas dos fenômenos de drapejamento (flutter) e de martelamento (buffeting). A discretização da estrutura é efetuada pelo método dos elementos finitos e a redução dos graus de liberdade é realizada por superposição modal com modos selecionados que melhor descrevem os movimentos do tabuleiro. Utiliza-se modelo matemático reduzido para a análise multimodal no domínio do tempo e da freqüência. A velocidade crítica ou velocidade de drapejamento é determinada por procedimento de autovalores complexos com a obtenção de freqüências e taxas de amortecimentos modais para várias velocidades do vento. Adicionalmente, o fenômeno do drapejamento é estudado por séries temporais de respostas de coordenadas generalizadas e de deslocamentos selecionados e por análise espectral dessas séries temporais, que permitem a verificação das características de vibração do tabuleiro da ponte no domínio da freqüência. O estudo do fenômeno de martelamento considera esforços aeroelásticos determinísticos e esforços aerodinâmicos estocásticos e apresentam-se resultados em espectros de potência de deslocamentos e em desvios padrão de deslocamentos ao longo do tabuleiro. Para validar o sistema ANA-PSp, apresentam-se estudos de caso para a ponte estaiada da Normandia, para a ponte pênsil colapsada de Tacoma Narrows e para a ponte estaiada projetada, mas não executada, sobre o Rio Tietê e localizada na extremidade do complexo viário Jacu-Pêssego. / The architectonic characteristics and the structural performance of suspension bridges and cable-stayed bridges have determined their growing use on large span bridges. This growing usage, which has occurred world-wide during the last decades, is now being repeated in Brazil during the last few years. Several such bridges are presently either undergoing construction or being designed. One of the outstanding aspects in the structural analysis of suspension bridges is their behavior under wind action. This paper presents the computer system ANA-PSp, specially developed for studying the movement of suspended bridge decks under aeroelastic and aerodynamic forces. This computer system is formed by a group of subsystems and is created for aeroelastic analysis of suspended bridges under wind action. It allows extended parametric analyses of the flutter and the buffeting phenomena. Structural discretization is done by the finite element method and the reduction of degrees of freedom is obtained by modal superposition of the selected modes which best describe the deck movements. A reduced mathematical model is used for the multimodal analysis in the time and frequency domains. Critical velocity or flutter velocity is determined by a procedure of complex eigenvalues which obtains frequencies and damping ratios for different wind speeds. Additionally, the flutter phenomenon is studied by temporal series of answers to generalized coordinate responses and of selected displacements by spectral analysis of such temporal series, which allow us to verify the characteristics of the vibrations of the bridge deck in the frequency domain. The study of the buffeting phenomenon considers deterministic aeroelastic and stochastic aerodynamic forces. The paper presents results in displacement power spectra and in the standard deviation of displacements along the deck. In order to validate system ANA-PSp, case studies are presented for the cable-stayed Ponte de Normandie in Le Havre (France), for the collapsed suspension bridge on Tacoma Narrows and for the cable-stayed bridge, already designed but not built, on Tietê River, located at one end of the highway complex Jacu-Pêssego (São Paulo, SP, Brazil).
27

Response of cable-stayed and suspension bridges to moving vehicles : Analysis methods and practical modeling techniques

Karoumi, Raid January 1998 (has links)
This thesis presents a state-of-the-art-review and twodifferent approaches for solving the moving load problem ofcable-stayed and suspension bridges. The first approach uses a simplified analysis method tostudy the dynamic response of simple cable-stayed bridgemodels. The bridge is idealized as a Bernoulli-Euler beam onelastic supports with varying support stiffness. To solve theequation of motion of the bridge, the finite difference methodand the mode superposition technique are used. The second approach is based on the nonlinear finite elementmethod and is used to study the response of more realisticcable-stayed and suspension bridge models considering exactcable behavior and nonlinear geometric effects. The cables aremodeled using a two-node catenary cable element derived using"exact" analytical expressions for the elastic catenary. Twomethods for evaluating the dynamic response are presented. Thefirst for evaluating the linear traffic load response using themode superposition technique and the deformed dead load tangentstiffness matrix, and the second for the nonlinear traffic loadresponse using the Newton-Newmark algorithm. The implemented programs have been verified by comparinganalysis results with those found in the literature and withresults obtained using a commercial finite element code.Several numerical examples are presented including one for theGreat Belt suspension bridge in Denmark. Parametric studieshave been conducted to investigate the effect of, among others,bridge damping, bridge-vehicle interaction, cables vibration,road surface roughness, vehicle speed, and tuned mass dampers.From the numerical study, it was concluded that road surfaceroughness has great influence on the dynamic response andshould always be considered. It was also found that utilizingthe dead load tangent stiffness matrix, linear dynamic trafficload analysis give sufficiently accurate results from theengineering point of view. / QC 20100511
28

ANA-PSp: um sistema computacional para análise aeroelástica de pontes suspensas por modelos matemáticos reduzidos. / Ana-PSp: a computational system for aeroelastic analysis of suspended bridges for reduced mathematical models.

Eri Sato Kreis 22 November 2007 (has links)
As características arquitetônicas e o desempenho estrutural de pontes suspensas, estaiadas ou pênseis, têm determinado a sua crescente utilização em obras de arte destinadas a vencer grandes vãos. Essa utilização crescente que ocorreu no mundo nas últimas décadas se repete agora nos últimos anos no país. Várias dessas obras estão em execução e em projeto. Um dos aspectos relevantes na análise estrutural das pontes suspensas é o de seu comportamento quando submetidas à ação do vento. Apresenta-se o sistema computacional ANA-PSp desenvolvido especialmente para o estudo do movimento de tabuleiros de pontes suspensas sujeitas a esforços aeroelásticos e aerodinâmicos. Esse sistema computacional formado por um conjunto de subsistemas, é elaborado para a análise aeroelástica de pontes suspensas sob a ação de vento e permite análises paramétricas extensas dos fenômenos de drapejamento (flutter) e de martelamento (buffeting). A discretização da estrutura é efetuada pelo método dos elementos finitos e a redução dos graus de liberdade é realizada por superposição modal com modos selecionados que melhor descrevem os movimentos do tabuleiro. Utiliza-se modelo matemático reduzido para a análise multimodal no domínio do tempo e da freqüência. A velocidade crítica ou velocidade de drapejamento é determinada por procedimento de autovalores complexos com a obtenção de freqüências e taxas de amortecimentos modais para várias velocidades do vento. Adicionalmente, o fenômeno do drapejamento é estudado por séries temporais de respostas de coordenadas generalizadas e de deslocamentos selecionados e por análise espectral dessas séries temporais, que permitem a verificação das características de vibração do tabuleiro da ponte no domínio da freqüência. O estudo do fenômeno de martelamento considera esforços aeroelásticos determinísticos e esforços aerodinâmicos estocásticos e apresentam-se resultados em espectros de potência de deslocamentos e em desvios padrão de deslocamentos ao longo do tabuleiro. Para validar o sistema ANA-PSp, apresentam-se estudos de caso para a ponte estaiada da Normandia, para a ponte pênsil colapsada de Tacoma Narrows e para a ponte estaiada projetada, mas não executada, sobre o Rio Tietê e localizada na extremidade do complexo viário Jacu-Pêssego. / The architectonic characteristics and the structural performance of suspension bridges and cable-stayed bridges have determined their growing use on large span bridges. This growing usage, which has occurred world-wide during the last decades, is now being repeated in Brazil during the last few years. Several such bridges are presently either undergoing construction or being designed. One of the outstanding aspects in the structural analysis of suspension bridges is their behavior under wind action. This paper presents the computer system ANA-PSp, specially developed for studying the movement of suspended bridge decks under aeroelastic and aerodynamic forces. This computer system is formed by a group of subsystems and is created for aeroelastic analysis of suspended bridges under wind action. It allows extended parametric analyses of the flutter and the buffeting phenomena. Structural discretization is done by the finite element method and the reduction of degrees of freedom is obtained by modal superposition of the selected modes which best describe the deck movements. A reduced mathematical model is used for the multimodal analysis in the time and frequency domains. Critical velocity or flutter velocity is determined by a procedure of complex eigenvalues which obtains frequencies and damping ratios for different wind speeds. Additionally, the flutter phenomenon is studied by temporal series of answers to generalized coordinate responses and of selected displacements by spectral analysis of such temporal series, which allow us to verify the characteristics of the vibrations of the bridge deck in the frequency domain. The study of the buffeting phenomenon considers deterministic aeroelastic and stochastic aerodynamic forces. The paper presents results in displacement power spectra and in the standard deviation of displacements along the deck. In order to validate system ANA-PSp, case studies are presented for the cable-stayed Ponte de Normandie in Le Havre (France), for the collapsed suspension bridge on Tacoma Narrows and for the cable-stayed bridge, already designed but not built, on Tietê River, located at one end of the highway complex Jacu-Pêssego (São Paulo, SP, Brazil).
29

O uso do GPS como instrumento de controle de deslocamentos dinâmicos de obras civis - aplicação na área de transportes / The use of GPS as control instrument of dynamic displacements of civil structures

Ana Paula Camargo Larocca 25 June 2004 (has links)
Este trabalho apresenta o desenvolvimento de metodologia para avaliar a utilização do Sistema de Posicionamento Global (GPS) como ferramenta de pesquisa no estudo do comportamento dinâmico de obras viárias. Para ser caracterizado como um instrumento de medição, foi estudada a potencialidade de um método, que se fundamenta numa forma específica de coleta e processamento de dados GPS; análise dos resíduos resultantes do processamento da dupla diferença de fase e aplicação de análise espectral para filtragem de informações indesejáveis (multicaminhamento dos sinais GPS). A coleta envolve um oscilador eletro-mecânico, especialmente projetado, que permite calibrar as medidas de amplitude e freqüência das oscilações mensuráveis pela obra sob teste. Inúmeros experimentos foram realizados em ambientes de reflexões e difrações variáveis e com diversos tipos de receptores e antenas GPS. Alguns ensaios foram realizados utilizando, simultaneamente, equipamentos como transdutores de deslocamento, acelerômetros e estações totais. Comparando os resultados obtidos, mesmo com valores prescritos em normas e códigos, afirma-se que o GPS, sob o método de coleta de dados testado, é um instrumento confiável para detecção e caracterização do comportamento dinâmico de estruturas, apresentado confiabilidade para as medições realizadas, da ordem de décimos de milímetro. Quanto à detecção das freqüências, as mais baixas ficam comprometidas pela presença do multicaminhamento e as mais elevadas têm a detecção limitada pela máxima taxa de coleta dos receptores (Lei de Nyquist) / This work presents the development of a methodology to appraise the use of Global Positioning System (GPS) as a tool for researching of dynamic behavior of road transport structures. To be characterized as an instrument for measuring it was studied the potentiality of one method which includes a specific mode of GPS data collection; analyses of double difference phase residuals and application of spectral analyses and filtering for excluding undesirable information (multipath). The GPS data collected applies an electro-mechanical oscillator, specially built for that, which permits to calibrate the measures of frequency and amplitude of structure’s oscillations under dynamic load test. Several field tests were carried out in vicinities with high and low capacity of causing signal reflections and diffractions and with different types of GPS receivers and GPS antennas. A couple of fields were carried out using, at the same time, transducers of displacement, accelerometers and total stations. Comparing these results obtained even with values of codes, it is affirmed that GPS, under the data collection method tested, it is a trustworthy instrument for detection and characterization of dynamic behavior of structures, presenting reliability of measures ranging around tenths of millimeters. The very low frequencies are highly degraded by multipath and very high frequencies have its detection limited by the receiver data rate (Theorem’s Nyquist)
30

Frequency Domain Analysis of Composite Long-Span Cable-Stayed Bridges by Finite Strip Method

Li, Haoran January 2017 (has links)
The finite strip method (FSM) is a very efficient numerical method employed for performing the structural analysis of slender structures, such as cable-stayed bridges; the strip discretization of the model allows for the usage of a lower number of degrees of freedom, in comparison with the finite element method (FEM), while, as it will be discussed in the current research, the results obtained from both methods are in relatively good agreement. Moreover, to address the latest developments in the area of smart construction materials used for long-span bridges, the fiber reinforced polymer (FRP) composites were implemented for the bridge deck modeling, as part of a hybrid composite FRP cable-stayed bridge, and an extend laminate integrated finite strip method (LFSM) was applied for estimating the static structural performance of the hybrid composite FRP long-span cable-stayed bridge under several concentrated and uniformly distributed loadings. The free vibrations analysis was conducted for the Kap Shui Mun Cable-stayed Bridge model, and the natural frequencies were compared with the ones obtained from an FE model of the same bridge. One of the advantages of using the integrated finite strip method is that number of vibration modes, which can be included in the dynamic analysis when the effect of a sweeping sinus and a seismic loading are investigated when a conventional FE analysis would fail to converge. The outcomes of this research will set the stage for the hybrid long-span cable-stayed bridges modeling by the laminate integrated finite strip method (LFSM) which is more efficient and straightforward than the finite element analysis, for performing the static, free vibration, time domain, and frequency domain analyses.

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