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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

Modelagem do comportamento dinâmico de passarelas tubulares em aço e mistas (aço-concreto) / Modeling of the dynamic behaviour of composite (steel-concrete) tubular foot bridges

Gilvan Lunz Debona 09 December 2011 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A experiência dos engenheiros estruturais e os conhecimentos adquiridos pelo uso de materiais e novas tecnologias, têm ocasionado estruturas de aço e mistas (aço-concreto) de passarelas cada vez mais ousadas. Este fato tem gerado estruturas de passarelas esbeltas, e consequentemente, alterando os seus estados de limite de serviço e último associados ao seu projeto. Uma consequência direta desta tendência de projeto é o aumento considerável das vibrações das estruturas. Portanto, a presente investigação foi realizada com base em um modelo de carregamento mais realista, desenvolvido para incorporar os efeitos dinâmicos induzidos pela caminhada de pessoas. O modelo de carregamento considera a subida e a descida da massa efetiva do corpo em cada passo. A posição da carga dinâmica também foi alterada de acordo com a posição do pedestre sobre a estrutura e a função do tempo gerada, possui uma variação espacial e temporal. O efeito do calcanhar do pedestre também foi incorporado na análise. O modelo estrutural investigado baseia-se em uma passarela tubular (aço-concreto), medindo 82,5m. A estrutura é composta por três vãos (32,5 m, 20,0 m e 17,5 m, respectivamente) e dois balanços (7,5 m e 5,0 m, respectivamente). O sistema estrutural é constituído por perfis de aço tubular e uma laje de concreto, e é atualmente utilizada para travessia de pedestres. Esta investigação é realizada com base em resultados experimentais, relacionando a resposta dinâmica da passarela com as obtidas via modelos de elementos finitos. O modelo computacional proposto adota as técnicas de refinamento de malha, usualmente presente em simulações pelo método de elementos finitos. O modelo de elementos finitos foi desenvolvido e validado com resultados experimentais. Este modelo de passarela tubular permitiu uma avaliação dinâmica completa, investigando especialmente ao conforto humano e seus limites de utilização associados à vibração. A resposta dinâmica do sistema, em termos de acelerações de pico, foi obtida e comparada com os valores limites propostos por diversos autores e padrões de projeto. As acelerações de pico encontradas na presente análise indicou que a passarela tubular investigada apresentou problemas relacionados com o conforto humano. Por isso, foi detectado que este tipo de estrutura pode atingir níveis de vibrações excessivas que podem comprometer o conforto do usuário na passarela e especialmente a sua segurança. / The structural engineers experience and knowledge allied by the use newly developed materials and technologies have produced steel and composite (steel-concrete) footbridges with daring structures. This fact have generated very slender structural footbridges and consequently changed the serviceability and ultimate limit states associated to their design. A direct consequence of this design trend is a considerable increase of structural vibrations. Therefore, the present investigation was carried out based on a more realistic load model developed to incorporate the dynamic effects induced by people walking. The load model considered the ascent and descending movement of the human body effective mass at each step. The position of the dynamic load was also changed according to the individual position and the generated time function, having a space and time description. The effect of the human heel was also incorporated in the analysis. The investigated structural model was based on a tubular composite (steel-concrete) footbridge, spanning 82.5 m. The structure is composed by three spans (32.5 m, 17.5 m and 20.0 m, respectively) and two overhangs (7.5 m and 5.0 m, respectively). The structural system is constituted by tubular steel sections and a concrete slab and is currently used for pedestrian crossing. This investigation is carried out based on correlations between the experimental results related to the footbridge dynamic response and those obtained with finite element models. The proposed computational model adopted the usual mesh refinement techniques present in finite element method simulations. The finite element model has been developed and validated with the experimental results. This model enabled a complete dynamic evaluation of the investigated tubular footbridge especially in terms of human comfort and its associated vibration serviceability limit states. The system dynamic response, in terms of peak accelerations, was obtained and compared to the limiting values proposed by several authors and design standards. The peak accelerations found in the present analysis indicated that the investigated tubular footbridge presented problems related with human comfort. Hence it was detected that this type of structure can reach high vibration levels that can compromise the footbridge users comfort and especially its safety.
2

Modelagem do comportamento dinâmico de passarelas tubulares em aço e mistas (aço-concreto) / Modeling of the dynamic behaviour of composite (steel-concrete) tubular foot bridges

Gilvan Lunz Debona 09 December 2011 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A experiência dos engenheiros estruturais e os conhecimentos adquiridos pelo uso de materiais e novas tecnologias, têm ocasionado estruturas de aço e mistas (aço-concreto) de passarelas cada vez mais ousadas. Este fato tem gerado estruturas de passarelas esbeltas, e consequentemente, alterando os seus estados de limite de serviço e último associados ao seu projeto. Uma consequência direta desta tendência de projeto é o aumento considerável das vibrações das estruturas. Portanto, a presente investigação foi realizada com base em um modelo de carregamento mais realista, desenvolvido para incorporar os efeitos dinâmicos induzidos pela caminhada de pessoas. O modelo de carregamento considera a subida e a descida da massa efetiva do corpo em cada passo. A posição da carga dinâmica também foi alterada de acordo com a posição do pedestre sobre a estrutura e a função do tempo gerada, possui uma variação espacial e temporal. O efeito do calcanhar do pedestre também foi incorporado na análise. O modelo estrutural investigado baseia-se em uma passarela tubular (aço-concreto), medindo 82,5m. A estrutura é composta por três vãos (32,5 m, 20,0 m e 17,5 m, respectivamente) e dois balanços (7,5 m e 5,0 m, respectivamente). O sistema estrutural é constituído por perfis de aço tubular e uma laje de concreto, e é atualmente utilizada para travessia de pedestres. Esta investigação é realizada com base em resultados experimentais, relacionando a resposta dinâmica da passarela com as obtidas via modelos de elementos finitos. O modelo computacional proposto adota as técnicas de refinamento de malha, usualmente presente em simulações pelo método de elementos finitos. O modelo de elementos finitos foi desenvolvido e validado com resultados experimentais. Este modelo de passarela tubular permitiu uma avaliação dinâmica completa, investigando especialmente ao conforto humano e seus limites de utilização associados à vibração. A resposta dinâmica do sistema, em termos de acelerações de pico, foi obtida e comparada com os valores limites propostos por diversos autores e padrões de projeto. As acelerações de pico encontradas na presente análise indicou que a passarela tubular investigada apresentou problemas relacionados com o conforto humano. Por isso, foi detectado que este tipo de estrutura pode atingir níveis de vibrações excessivas que podem comprometer o conforto do usuário na passarela e especialmente a sua segurança. / The structural engineers experience and knowledge allied by the use newly developed materials and technologies have produced steel and composite (steel-concrete) footbridges with daring structures. This fact have generated very slender structural footbridges and consequently changed the serviceability and ultimate limit states associated to their design. A direct consequence of this design trend is a considerable increase of structural vibrations. Therefore, the present investigation was carried out based on a more realistic load model developed to incorporate the dynamic effects induced by people walking. The load model considered the ascent and descending movement of the human body effective mass at each step. The position of the dynamic load was also changed according to the individual position and the generated time function, having a space and time description. The effect of the human heel was also incorporated in the analysis. The investigated structural model was based on a tubular composite (steel-concrete) footbridge, spanning 82.5 m. The structure is composed by three spans (32.5 m, 17.5 m and 20.0 m, respectively) and two overhangs (7.5 m and 5.0 m, respectively). The structural system is constituted by tubular steel sections and a concrete slab and is currently used for pedestrian crossing. This investigation is carried out based on correlations between the experimental results related to the footbridge dynamic response and those obtained with finite element models. The proposed computational model adopted the usual mesh refinement techniques present in finite element method simulations. The finite element model has been developed and validated with the experimental results. This model enabled a complete dynamic evaluation of the investigated tubular footbridge especially in terms of human comfort and its associated vibration serviceability limit states. The system dynamic response, in terms of peak accelerations, was obtained and compared to the limiting values proposed by several authors and design standards. The peak accelerations found in the present analysis indicated that the investigated tubular footbridge presented problems related with human comfort. Hence it was detected that this type of structure can reach high vibration levels that can compromise the footbridge users comfort and especially its safety.
3

Analysis of Walking and Route-Choice Behavior of Pedestrians inside Public Transfer Stations : A Study on how pedestrians behave in the approaching vicinity of level-change facilities,and how it affects their walking and route-choice behavior

Monte Malveira, Daniel January 2019 (has links)
Pedestrian walking and choice behavior presented was first studied by Fruin in 1971, and since then a lot of research have been carried out in order to understand how humans move and what does make them make choices and obtain certain patterns. In relation to pedestrians, a significant bottleneck inside public stations evaluated by research are the level-change facilities, as Stair Walks and Escalators. The aim of this research is studying how pedestrian behave in the vicinity to stairways and escalators, and how does that affect pedestrian choice, speed and acceleration when choosing one of the two facilities. Also, with a need for more data on pedestrian traffic, further data collection is a big requirement to analyze their behavior and use as tools in future measures. At last, how to optimize the movement of pedestrians in relation to level changes, considering the effects of the movements observed. Two case studies were analysed, Stockholm Central Station and Uppsala Central Station.The study compares data collection methods, tracking methods and previous studies to better fit the scope of this research. The data is backed up from previous research and explains which method better fitted the options available. As a result, video data collection was chosen to collect the data, a semi-automatic tracking software called T-analyst was used to extract speed, trajectories and acceleration from the videos, and microsimulation modelling from VISSIM further investigated different design options to optimize the overall performance and improve travel time in the same area. The analysis found out that there was a possibility to increase the overall performance of the location in higher flow levels, where the most significant queues could be seen, since there was the possibility to achieve higher speeds by modifying the width and position of the stair walks, which allow for a smaller queue in both directions.
4

Fotgängares gånghastigheter i bytespunkter för kollektivtrafik

Jegenberg, Minna, Lundström, Kristina January 2017 (has links)
Walking speeds are an important parameter in the process of designing for example arenas, malls and station environments, to be able to make them safe and comfortable for the users. Previous studies have mainly focused on pedestrian walking speeds at zebra crossings and the results of these are the basis for traffic signal timing. The studies have also investigated the relationship between walking speed and gender, age and density of pedestrians. From the results of these studies, conclusions have been drawn that these three factors have an impact on pedestrian walking speeds. To make microsimulations of pedestrians reflect reality as well as possible, pedestrian walking speeds should be investigated at regular intervals, as walking speeds change with the ongoing change of the composition of the population. In the simulation of station environments, pedestrian speeds should also be used that have been measured in these types of environments. Alternatively, the speeds should be measured at locations near stations, rather than using speeds from zebra crossings. As a step in improving the above-mentioned microsimulations, the aim of this work is to study walking speeds at a public transport hub during rush hour. The work also focuses on connecting walking speeds to each sex and level of crowding. To achieve this goal, video recordings were performed at the exchange point between Stockholms östra and Tekniska högskolan in Stockholm, Sweden, where public transport passengers change between light rail and subway. Analysis of the video films resulted in walking speeds which were higher than those previously measured at zebra crossings. The most obvious factors explaining this are the differences in the environment where the studies were conducted and that the walking speeds in this thesis were measured during rush hour. The results show that simulations of stations and locations nearby should not be based on walking speeds measured at zebra crossings. Analysis of the video films also resulted in the calculated mean walking speed of women being marginally lower than for men. Regarding the link between density of pedestrians and their walking speeds a conclusion can be drawn that at low densities pedestrians have good opportunities to freely select their own walking speed. The freely chosen walking speed which can thus be maintained at low densities can vary widely between different individuals. At higher, unlike at lower densities, it is difficult for pedestrians to maintain a freely chosen speed due to interactions with other pedestrians. The calculated average walking speed at higher densities therefor decreases as the density increases. Interactions with other pedestrians can either mean that a pedestrian is forced to lower the speed or that he or she must walk faster to keep up with the current pace. When analyzing the video films, several other factors effecting the walking speed could be noted. Of these factors, grouping of pedestrians and if the pedestrian is using a phone or carrying luggage could be seen to decrease the pedestrian speed. These factors’ impact on walking speeds was only superficially studied in this thesis, and no reliable conclusions can therefore be drawn. Keywords: Pedestrian walking speed, public transport traffic hub, density of pedestrians, Level of
5

Pedestrian Walking Speeds at Signalized Intersections in Utah

Berrett, Jordi Jordan 01 March 2019 (has links)
The 2009 edition of the Manual on Uniform Traffic Control Devices (MUTCD) recommends a pedestrian walking speed of 3.5 feet per second for use in the timing of pedestrian clearance intervals at signalized intersections (reduced from 4.0 feet per second in the 2003 edition). Jurisdictions across the state of Utah continue to maintain pedestrian walking speeds of 4.0 feet per second for normal intersections with guidance on engineering judgement for areas where a lower pedestrian walking speed should be considered. In 2018, it was decided that the current state guidance with regard to pedestrian walking speeds be evaluated for any needed changes, such as adopting the national guidance found in the 2009 MUTCD. To evaluate pedestrian walking speeds at signalized intersections, 15 sites throughout the state of Utah were studied, producing a total of 2,061 observations of pedestrian crossing events. These crossing events were evaluated to calculate walking speeds in relation to pedestrian demographics at each location. Evaluated demographics included pedestrian group size, gender, mobility status, age category, alertness, and potential distractions. Upon completion of data collection, a statistical analysis was conducted to determine mean and 15th percentile pedestrian walking speeds by demographic. The data collection procedure, data analysis, and limited recommendations for pedestrian start-up delay and pedestrian walking speeds as used in signal timing are discussed in this report. The data suggest that Utah continue to maintain its guidance of 4.0 feet per second walking speeds at most signalized intersections, while exercising engineering judgment at locations containing high pedestrian volumes or locations containing high percentages of elderly or disabled pedestrians.

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