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Mobile LiDAR for Monitoring MSE Walls with Smooth and Textured Precast Concrete PanelsMohammed D Aldosari (8333136) 22 January 2020 (has links)
Mechanically Stabilized Earth (MSE) walls retain soil on steep, unstable slopes with crest loads. Over the last decade, they are becoming quite popular due to their low cost-to-benefit ratio, design flexibility, and ease of construction. Like any civil infrastructure, MSE walls need to be continuously monitored according to transportation asset management criteria during and after the construction stage to ensure that their expected serviceability measures are met and to detect design and/or construction issues, which could lead to structural failure. Current approaches for monitoring MSE walls are mostly qualitative (e.g., visual inspection or examination). Besides being time consuming, visual inspection might have inconsistencies due to human subjectivity. Other monitoring approaches are based on using total station, geotechnical field instrumentations, and/or Static Terrestrial Laser Scanning (TLS). These instruments are capable of providing highly accurate, reliable performance measures. However, the underlying data acquisition and processing strategies are time-consuming and are not scalable. This research focuses on a comprehensive strategy using a Mobile LiDAR Mapping System (MLS) for the acquisition and processing of point clouds covering the MSE wall. The strategy produces standard serviceability measures, as defined by the American Association of State Highway and Transportation Officials (AASHTO) – e.g., longitudinal and transversal angular distortions. It also delivers a set of recently developed measures (e.g., out-of-plane offsets and 3D position/orientation deviations for individual panels constituting the MSE wall). Moreover, it is also capable of handling MSE walls with smooth or textured panels with the latter being the focus of this research due to its more challenging nature. For this study, an ultra-high-accuracy wheel-based MLS has been developed to efficiently acquire reliable data conducive to the development of the standard and new serviceability measures. To illustrate the feasibility of the proposed acquisition/processing strategy, two case studies in this research have been conducted with the first one focusing on the comparative performance of static and mobile LiDAR in terms of the agreement of the derived serviceability measures. The second case study aims at illustrating the feasibility of the proposed strategy in handling large textured MSE walls. Results from both case studies confirm the potential of using MLS for efficient, economic, and reliable monitoring of MSE walls.
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Spojitý komorový most / Continuous box girder bridgeHajnoš, Mário January 2022 (has links)
The topic of this thesis is detailed design of supporting structure of continous box girder bridge across a deep valley called Lazný creek. The bridge have to pass the second class road with category S 9,5. The design is processed by two options. The chosen option is designed as a girder with five spans 44,8 m + 55 m + 55 m + 55 m +44,8 m. Total length of bridge is 268,57 m, the main girder is gradually cast into the formwork suspended on a special ceiling scaffolding. The axis of the bridge is in a plan straight with the constant transversal slope 2,5 %. The thesis contains six models in software SCIA ENGINEER. Part of the work is situated on time depended analysis with construction phases. Assesment of ultimate limit states and serviceability limit states were done by hand according to the valid standards and regulations. Structural analysis, drawing documentation and vizualization are parts of this work.
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A pre-study of the static behaviour of a single diagonal timber arch bridgeÖhgren, Lovisa, Åström, Malin January 2020 (has links)
The aim of this thesis is to study and gain more insight about the static behaviour of the three hinged single diagonal timber arch bridge in different situations. The bridge was tested for static analyses for both Ultimate Limit State and Serviceability Limit State, to investigate its behaviour and if it is possible to be built at the selected location. Furthermore, the dimensions of the elements are to be determined. Pre-studies on similar bridges have been done and their problems have been taken into account when analysing the behaviour of this bridge. Thereafter, two different designs have been constructed. The finite element software RFEM has been used in this project to be able to analyse the behaviour of the two different models. The in-plane buckling of the arch is the most critical part of the bridge and the bridge should therefore be designed regarding that. Additionally, different alternatives were suggested to reduce the deformation of the deck in the models. Finally, an optimized model is reached which consists of longitudinal beams and has an arch with a wide cross section.
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Dynamic Testing of In-Situ Composite Floors and Evaluation of Vibration Serviceability Using the Finite Element MethodBarrett, Anthony R. 06 October 2006 (has links)
The presented research examined three areas: best practices in high quality dynamic testing of in-situ floor systems, extensive dynamic testing of three bare (non-fit out) in-situ multi-bay steel composite floors to estimate their dynamic parameters/response and to identify trends in dynamic behavior, and development of a set of fundamental finite element (FE) modeling techniques to adequately represent the dynamic response of steel composite floors for the purpose of evaluating vibration serviceability. The measurement, analysis, and computation of a floor's accelerance frequency response function (FRF) is the core premise linking all areas of the presented research.
The burst chirp signal using an electrodynamic shaker is recommended as the most accurate and consistent source of excitation for acquiring high quality measurements suitable for use in parameter estimation, operating deflection shape animation, and calibration/validation of FE models. A reduced mid-bay testing scheme is recommended as a time-saving alternative to modal testing over a full coverage area, provided the only desired estimated parameters are frequencies, damping, and mid-bay acceleration response.
Accelerance FRFs were measured with an electrodynamic shaker located within 23 unique bays on the three tested floors. Dominant frequencies ranged from 4.85 Hz to 9 Hz and measured estimates of damping varied considerably, ranging from 0.44% to 2.4% of critical (0.5%-1.15% was typical). Testing showed several mode shapes were localized to just a few bays and not all modes were adequately excited by forcing at a single location. The quality of the estimated mode shapes was significantly improved using multi-reference modal testing.
FE models for the tested floors were developed based on high quality measured data and were shown to provide adequate representations of measured floor behavior. Fundamental techniques are presented for modeling mass, stiffness, boundary conditions, and performing dynamic analysis. A method of evaluating vibration serviceability was proposed using the FE model's computed accelerance FRF for comparison with a design accelerance curve that represents an acceleration response threshold in the frequency domain. An example design accelerance curve is presented based on current serviceability guidelines for acceleration tolerance and effective harmonic forces due to human activities such as walking. / Ph. D.
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Patient Data Management System (PDMS) : Anestesi- och intensivvårdspersonalens upplevelser av implementering och arbete med PDMS / Patient Data Management System (PDMS) : Anesthesia- and intensive care staff experiences of implementation and work with PDMSOrtscheid, Julius, Jensen, Thomas January 2017 (has links)
Titel: Patient Data Management System (PDMS) – Anestesi- och intensivvårdspersonalens upplevelser av implementering och arbete med PDMS. Bakgrund: Dagens och framtidens sjukvård innebär en ökande användning av digitala system i omvårdnaden. Patient Data Management System (PDMS) är ett kliniskt informationssystem och beslutsstöd som implementeras allt mer på svenska sjukhus. Tidigare forskning visar på skilda upplevelser av digitala systems påverkan på omvårdnaden, arbetsbelastning och tidsåtgång. Syfte: Syftet är att beskriva anestesi- och intensivvårdspersonalens upplevelser av implementering och arbete med PDMS. Metod: Studien genomfördes som en intervjustudie med kvalitativ ansats. Resultat: I resultatet framträder fyra teman, införandeprocessen, användarvänlighet, informationsöverföring samt patientsäkerhet. Dessa fyra teman skildrar vårdpersonalens upplevelser av införandet och arbetet med PDMS. Konklusion: PDMS implementeras på allt fler sjukhus i Sverige. Vårdpersonalen anser att det är mycket viktigt med information och utbildning inför implementeringen av PDMS. Helhetssynen på sjukhusets datasystem är viktigt då det framkommer att olika system inte alltid kommunicerar med varandra. Det leder till ökad arbetsbelastning och ökad risk för patientsäkerheten. Mer forskning om PDMS påverkan på omvårdnadsarbetet och patientsäkerheten behövs. / Title: Patient Data Management System (PDMS) – Anesthesia- and intensive care staff experiences of implementation and work with PDMS. Background: Todays and future healthcare means an increasing use of digital systems in nursing care. Patient Data Management System (PDMS) is a clinical information system and clinical decision support which is implemented in swedish hospitals. Previous research shows different experiences of digital systems impact on nursing care, workload and patient safety. Aim: The purpose was to describe anesthesia- and intensive care unit staff experiences of implementation and work with PDMS. Method: The study was conducted by interviews with a qualitative approach. Results: In the result four themes appear, process of introduction, serviceability, transfer of information and patient safety. The four themes depict the anesthesia- and intensive care unit staff experiences of the implementation and work with PDMS. Conclusion: PDMS is implemented in an increasing number of swedish hospitals. The anesthesia- and intensive care unit staff consider it very important with information and education before implementation of PDMS. The comprehensive view on the hospitals computer system is important due to the fact that these systems appear not to always be in synchronization with each other. That leads to an increased workload and also an increased risk regarding patient safety. More research on the PDMS impact on nursing and patient safety are needed.
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Comportamento em serviço de lajes mistas de aço e concreto ao longo do tempo / In service behavior of steel-concrete composite slabs under the long-term conditionsOliveira, Lucas Antônio Morais 29 April 2019 (has links)
O sistema estrutural de pisos com lajes mistas, também chamadas de lajes com fôrma de aço incorporada e popularmente conhecido como steel deck®, é de desenvolvimento recente no Brasil e tem ganhado espaço na indústria da construção civil. Pesquisas internacionais recentes têm mostrado que os efeitos da retração não-uniforme, da fluência e da fissuração são significativos para a evolução dos deslocamentos verticais. No entanto, não há referências na literatura nacional de investigações sobre o tópico, como é usual para as estruturas de concreto armado. Desta forma, o presente trabalho tem como foco estudar o comportamento em serviço de lajes mistas de aço e concreto, com ênfase nos deslocamentos verticais (flechas) diferidos no tempo. São considerados os efeitos da retração e da fluência do concreto, além da interação entre o perfil de aço e o concreto. Um programa experimental exploratório com dois protótipos de lajes mistas idênticas, uma submetida a um carregamento imposto e outra sujeita apenas ao peso próprio, submetidos a um ensaio de longa duração de 260 dias. Os deslocamentos foram medidos diariamente e as condições de temperatura e umidade do ambiente foram monitoradas. Observou-se a evolução das flechas diferidas ao longo dos 260 dias na ordem de 3,20 vezes maior que as flechas imediatas. Ensaios de flexão a quatro pontos foram realizados com as duas lajes submetidas ao ensaio de longa duração e a outras duas com idade de 28 dias, não sendo observado influência do tempo quanto à capacidade resistente das lajes mistas. Finalmente, abordagens analíticas de previsão de flechas foram aplicadas aos protótipos testados e também a outros modelos experimentais presentes na literatura. Os valores previstos por diferentes abordagens de avaliação foram comparados aos resultados experimentais, observando-se que as abordagens que não levam em conta os efeitos da retração não-uniforme e fluência tendem a subestimar a previsão. As abordagens com consideração dos efeitos diferidos apresentaram boa acurácia e destaca-se a importância da consideração dos efeitos dependentes do tempo na previsão dos deslocamentos verticais das lajes estudadas. / The structural floor system using steel-concrete composite slabs also called slabs with profiled steel decking and popularly known as steel deck®, has a recent development in Brazil and has taken space in the civil construction industry. Recent international researches have shown that non-uniform shrinkage, creep and cracking are significant for the time-dependent deflections of those slabs. However, there is no reference in the Brazilian literature of any study investigating the time-dependent behavior of composite slabs, as it is usual for reinforced concrete structures. So, this work focuses on the study of the in-service behavior of steel-concrete composite slabs under long-term conditions. The main emphasis lies on considering the time-dependent effects due to concrete shrinkage and creep, besides the influence of the steel-concrete interaction to calculate the slabs deflections. An exploratory experimental program with two prototypes of identical composite slabs, one subjected to an imposed loading and another subject only to self-weight, submitted to the 260-day long test. During all testing time, they were taken daily measurements of deflection and temperature and humidity conditions were monitored to understand its influence. The time-dependent deflections during the 260-days on the order of 3.20 times greater than the instantaneous deflection were observed. Four-point bending tests were performed with the two slabs submitted to the long-duration test 260-day and two others with a 28-day age. No influence of time was observed on the resistant capacity of composite slabs. Finally, analytical approaches to predict the deflections of the slabs were applied to the prototypes tested and other experimental tests from the literature. The calculated values by different evaluation approaches were compared to the experimental results. The evaluation approaches that do not take into account the effects of non-uniform shrinkage and creep tend to underestimate the previsions. The evaluation approaches considering the time-dependent effects presented good accuracy. The importance of the time-dependent effects for the deflections is demonstrated.
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Estudo das vibrações induzidas por pedestres em passarelas de madeira / Study of pedestrian-induced vibrations on timber footbridgesSegundinho, Pedro Gutemberg de Alcântara 17 May 2010 (has links)
No Brasil, o estudo a respeito das vibrações induzidas por pedestres em passarelas vem sendo realizado a partir do início dos anos 1990, para passarelas de concreto e de aço. No entanto, ainda não há registro de estudos desse tipo e a norma brasileira NBR 7190 (1997) de projeto de estruturas de madeira apresenta somente critérios de dimensionamento para carregamentos estáticos, no caso de passarelas de madeira. Nesse contexto, este trabalho tem como objetivo geral a análise teórica, numérica e experimental de passarelas de madeira simplesmente apoiadas, com vistas a propor recomendações de projeto relacionadas ao conforto humano nessas estruturas. Este estudo foi desenvolvido a partir da análise de diretrizes normativas e critérios sugeridos por diversos autores, da análise teórica de passarelas dimensionadas segundo os critérios da NBR 7190 (1997), de modelos numéricos construídos em elementos finitos e de ensaios experimentais em modelo reduzido. Entre as conclusões alcançadas, destaca-se que a formulação de Euler-Bernoulli é adequada para o cálculo da primeira frequência natural nas direções transversal vertical e transversal horizontal em passarelas de madeira simplesmente apoiadas; entretanto, especial atenção deve ser dada para a avaliação da rigidez à flexão na direção transversal horizontal. Finalmente, sugeriu-se uma proposta para verificação do estado limite de serviço devido às vibrações induzidas por pedestres em passarelas de madeira simplesmente apoiadas, no tocante ao cálculo de frequências e acelerações, a ser inserida na futura revisão da norma brasileira de projeto de estruturas de madeira. / In Brazil, studies about pedestrian-induced vibrations on footbridges have been carried out since the early 1990s, for concrete and steel footbridges. However, there is no record of such studies and the brazilian standard NBR 7190 (1997) for the design of timber structures only presents design requirements for static loads, in the case of timber footbridges. Therefore, this paper aims to general theoretical analysis, numerical and experimental simply-supported beams timber footbridges, with a view to proposing recommendations for projects related to human comfort in these structures. This study was developed from the study of standards guidelines and criteria suggested by several authors, the theoretical analysis of footbridges design according to the criteria of the NBR 7190 (1997), numerical models using finite element and experimental tests on reduced model. Among the conclusions reached, it is emphasized that the formulation of Euler-Bernoulli is suitable for calculating the first natural frequency in vertical and lateral directions simply-supported beams timber footbridges; however, special attention should be given to the evaluation of lateral bending stiffness. Finally, we have suggested a proposal serviceability limit state verification due to pedestrian-induced vibrations on simply-supported beams timber footbridges, concerning the calculation of frequencies and accelerations to be included in a future review of the brazilian standard for the design of timber structures.
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Passarela estaiada com tabuleiro de madeira laminada protendida em módulos curvos / Cable-stayed footbridge with stress laminated timber deck composed of curved modulesPletz, Everaldo 25 February 2003 (has links)
É inegável a importância do desenvolvimento de tecnologias de uso racional da madeira e de solução de problemas de transportes em nossas cidades, principalmente por causa do processo crescente de urbanização do mundo. Existe também, a necessidade estética de se unir à alta tecnologia, o belo. As passarelas estaiadas com tabuleiro de madeira laminada protendida, em módulos curvos, atendem a todas estas exigências. A construção de um protótipo permitiu que a realização de ensaios estáticos e dinâmicos, cujos resultados evidenciaram a viabilidade técnica e econômica de passarelas estaiadas usando madeira de reflorestamento, de tabuleiros compostos apenas por placas de madeira laminada protendida e da construção de placas curvas de madeira laminada protendida. Também foi possível comprovar que as vibrações induzidas por pedestres são a condição mais crítica de projeto. A investigação da perda de curvatura do tabuleiro demonstrou o sucesso do projeto, embora mais estudos ao longo do tempo sejam necessários. Baseando-se nos resultados experimentais, realizou-se a calibração do modelo numérico, que permitiu realizar simulações para determinar quais variáveis definem a resposta da passarela construída. Sugestões de procedimentos de elaboração e construção de passarelas, assim como de criação de norma brasileira específica para pontes e passarelas de madeira, são apresentadas. / The ongoing, worldwide, large scale urbanization is stressing more and more the importance of developing new technologies concerned with the rational use of timber and with the solution of transportation problems in cities. There is also an aesthetical need of showing the melting of up-to-date high technology with beauty. The cable-stayed stress laminated timber footbridge, with curved modules meets all these needs. The buildings of a prototype, enable static and dynamic tests to be carried out. The experimental results revealed the technical and economical feasibility of the following items: a) cable stayed footbridges with timber from reforestation, b) decks only made of stress laminated timber, c) curved plates of stress laminated timber. It also revealed that the human induced vibrations leads to the most critical design condition. The loss of deck curvature study indicated the need of further research considering the time effect, to confirm the initial sucess achieved. Based on the results of these testings, the calibration of the numerical model was done. In order to investigate which variables are responsible for the footbridge response, several simulations were performed with the calibrated model. Guidelines for design and building of timber footbridges are presented. The creation of a brazilian code for timber bridges and footbridges is also suggested.
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Nonlinear Finite Element Analysis of the Black River Bridge - A Serviceability StudyZaeem, Mohammed Rizwan H. 11 December 2013 (has links)
An attempt was made to predict the service life of the Black River Bridge using non-linear finite element analysis (NLFEA). Numerical modeling was performed using NLFEA software developed by Prof. Evan Bentz.
A large number of analytical studies were conducted to assess the strength and behaviour of the bridge under normal truck loading and at failure loads. It was determined that the bridge is shear critical. Location of trucks that would cause maximum deflection and highest crack widths were identified. It is believed that these findings will have a significant impact on physical measurements that can be incorporated into future bridges, helping researchers determine the locations in the bridge that are ideal for instrumentation.
Axial compression present in the bridge can significantly affect deflection and crack widths. Incorporating thermal and shrinkage effects into the NLFEA are recommended as topics for further research. Appropriate estimate of thermal and shrinkage strain will aid in better prediction of axial stresses.
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Nonlinear Finite Element Analysis of the Black River Bridge - A Serviceability StudyZaeem, Mohammed Rizwan H. 11 December 2013 (has links)
An attempt was made to predict the service life of the Black River Bridge using non-linear finite element analysis (NLFEA). Numerical modeling was performed using NLFEA software developed by Prof. Evan Bentz.
A large number of analytical studies were conducted to assess the strength and behaviour of the bridge under normal truck loading and at failure loads. It was determined that the bridge is shear critical. Location of trucks that would cause maximum deflection and highest crack widths were identified. It is believed that these findings will have a significant impact on physical measurements that can be incorporated into future bridges, helping researchers determine the locations in the bridge that are ideal for instrumentation.
Axial compression present in the bridge can significantly affect deflection and crack widths. Incorporating thermal and shrinkage effects into the NLFEA are recommended as topics for further research. Appropriate estimate of thermal and shrinkage strain will aid in better prediction of axial stresses.
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