The diploma thesis describes the design and assessment of steel footbridge for pedestrians and cyclists across the river Svratka in Brno. As the main material of structural elements was used steel S355. In the beginning is deal with two variants of structural system, which are compared with each other and the better variant is chosen. The main structural system of chosen variant consist of two parabolic arches bend down to each other on which is suspended by suspenders intermediate deck. The deck consist of two steel beams with floor beams and composite cencrete slab. The span length is 50 m.

A footbridge in Slussen is planned to be built and will connect the area of Gamla Stan with Sodermalm. As an increasing number of footbridges with large span tend to become more flexible and light these days, the corresponding dynamic problems due to decreased stiffness and mass draw much more attention. Specifically speaking, reduced stiffness and mass lead to smaller natural frequencies, which make the structure more sensitive to pedestrian-induced loading, especially in lateral direction. Fortunately, in this master thesis, only the vibration in vertical direction is focused due to that the footbridge in Slussen project uses enough lateral bracings to make sure that the safety of lateral vibration is kept at an acceptable level. In order to analyze dynamic response of the footbridge, the real footbridge structure is converted into a FE model by the commercial software LUSAS. In this thesis, four different kinds of critical standards are introduced, which are Sétra [8], Swedish standard Bro 2004 [9], ISO 10137 [5] and Eurocode respectively. By comparing these four criteria, Sétra and Eurocode are finally chosen to be the standard and guidelines for this project. They give the basic theories about how to model the pedestrian loading and provide critical values to check the accelerations in both vertical and lateral direction. By using FE software LUSAS, natural frequencies of the footbridge and the corresponding mode shapes can be calculated directly. Then, according to these results and relevant theories introduced by Sétra, the pedestrian loading can be modeled and the acceleration response of any specific mode can be obtained as well. Finally, based on the worst case with excessive acceleration, the methods to reduce dynamic response will be presented. Commonly, there are two ways to reduce acceleration response. One method is to increase the stiffness of the structure. However, the increased stiffness is always accompanied with increased mass of the structure. Because of this reason, the other way that installing dampers is widely used in recent years. In this thesis, the tuned mass dampers (TMDs) are introduced in detail as well as the information about the design principles of it. With important parameters known, TMDs can be added to the model to check how the accelerations can be reduced.

The subject of this student work is the design of a load-bearing steel structure of a footbridge for pedestrians. The footbridge connects two buildings in the locality of Brno - Bohunice. It includes the bridging of a road, car park and entrances of the both buildings. The construction of the footbridge is solved in three variants with the best variant selected.

Dynamic problems in footbridges, such as sensible vibrations caused by human induced loading, has on a number of occasions been observed. These vibrations are rarely an ultimate limit state problem, but can be perceived as unpleasant by the pedestrian. In design guidelines there are propositions for how to asses the dynamic problem. However, they only take the walking load into account. It has been shown that, in the case of a running load, accelerations that lie above the comfort zone can occur and that running loads are more severe than walking loads in some cases. It is possible that the running load case has to be considered in future guidelines, and finding a feasible design methodology demands a lot of work. In this thesis, a method aimed to be easily used by a designer is analyzed. The amplitude of acceleration received as a result from a dynamic analysis in a commercial FEM software, was reduced by reduction factors to generate accelerations closer to reality. This could be identified and verified against recommendations.

The influence of the hanger configuration in the arch and deck bending moments under asymmetric loads is widely used nowadays for improved designs of arch bridges. In this work, by means of a parametric study, those hanger configurations that most efficiently increase both the natural frequencies and buckling factors are identified, simultaneously evaluating the dynamic and static performance of timber arch footbridges. A parametric FEM model allows to evaluate the performance of vertical, Nielsen, fan and network hanger configurations together with combinations of them among others for a three-hinge timber arch. The impact of other relevant design choices such as the number of hinges in the arch or the arch slenderness ratio is jointly addressed allowing for design recommendations. The results show a convergence of the natural frequencies regardless of the configuration of the hangers when increasing the number of them. Moreover, the performance of the studied hanger configurations is improved by introducing inclined hangers significantly increasing natural frequencies and buckling factors of the system. This highlights the importance of the stabilizing horizontal reaction appearing at the deck hanger anchor points and thereby improving the bending moment distribution at the arch. Furthermore, the analyses show that the combination of Nielsen and vertical hangers achieves both the largest natural frequency and buckling factor for a reasonable number of hangers. This contrasts with the low sensitivity of the static and dynamic performance that the vertical hanger configuration shows in relation to changes in the number of hangers, arch rise or arch stiffness among others. Additionally, an important consideration when designing three hinge arch bridges is found to be to prevent a local buckling mode from appearing at the crown of the arch. This can also be done by the right choice of the number and configuration of hangers, as has been shown in the thesis. The results produced in this work can be used to guide engineers towards designing arch bridges with higher static capacity and better dynamic performance while reducing at the same time the material consumption. Furthermore, the findings of the work open up the way towards optimization of arch bridge structures.

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Diploma´s thesis is about timber structure of footbridge for pedestrians and cyclists over the Slatina river in the city of Zvolen as cast of alternatives. In the first alternative is footbridge designed as a simple arched beam, made of glued laminated timber. Footbridge is also designed with semi through bridge deck, made of structural timber. The second alternative is designed as a tied arch structure. At this alternative is the bridge deck left unchanged(material, sizes of members). Both alternatives are attested by currents standarts.

Made available in DSpace on 2015-05-08T14:59:33Z (GMT). No. of bitstreams: 1 parte1.pdf: 2316235 bytes, checksum: 0033949f9aa3743186479e5db2794978 (MD5) Previous issue date: 2011-03-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In large span footbridges, it has been observed that pedestrian traffic can induce low frequency oscillations. The proximity between the natural frequencies of the structure and the frequencies of the excitation can result in the occurrence of resonance phenomenon, causing difficulties to use the structure for fear of its collapse on the part of users. Notably, the increased amplitude of the vibration, in the lateral direction that have been induced by crowds of pedestrians were brought to attention by the behavior of some footbridges that presented excessive vibration in this direction such as the Millennium Bridge in London, Solferino Bridge in Paris, among others. The lateral movement can cause alteration on the movement of the center of gravity of the pedestrian during the crossing and thus discomfort to transit on it. On the other hand, the lateral movement of the structure can induce synchronization between pedestrians and the structure s own move, resulting in amplification of vibrations, a phenomenon identified in the literature by lock-in. However, research on the relationship between frequency and amplitude of motion of the structure and percentage of synchronization that this motion induces on the pedestrians are incipient, which hampers the development of mathematical models to analyze the phenomenon. To investigate this phenomenon, we developed a control system using fuzzy logic to control a pneumatic system excitation applied in a prototype footbridge built in the laboratory. The system was conceived to provide oscillatory movement, with control of frequency and amplitude. Results showed that pedestrians tend to synchronize with the footbridge, causing the lock-in effect in the lateral direction, when the footbridge lateral oscillation approaches by half of the pedestrian pacing rate in vertical direction. / Em passarelas de grande vão, vêm sendo observado que o tráfego de pedestres pode induzir oscilações de baixas frequências. A proximidade entre as frequências naturais da estrutura e as frequências de excitação pode resultar na ocorrência do fenômeno de ressonância, ocasionando dificuldades de uso da estrutura por receio de seu colapso por parte dos usuários. Notadamente, o aumento da amplitude das vibrações, na direção lateral, induzidas por multidões de pedestres, chamou à atenção pelo comportamento de várias passarelas que apresentaram vibrações excessivas nesta direção, tais como a Millennium Bridge, em Londres; Solferino Bridge em Paris; entre outras. O efeito do movimento lateral da passarela ocasiona alteração do movimento do centro de gravidade do pedestre durante seu percurso sobre a mesma e, desta forma, desconforto ao transitar sobre ela. Por outro lado, tal efeito pode induzir uma sincronização entre o caminhar dos pedestres na estrutura e o próprio movimento da estrutura, resultando em amplificação das vibrações, um fenômeno identificado na literatura por lock-in. Entretanto, investigações sobre a relação entre amplitudes e frequências do movimento da estrutura e percentual de sincronização que tal movimento induz nos pedestres são incipientes, o que dificulta o desenvolvimento de modelos matemáticos para analisar o fenômeno. Para investigação desse fenômeno, foi desenvolvido um sistema de controle, utilizando lógica fuzzy, para controlar um sistema pneumático de excitação aplicado em um protótipo de passarela construído em laboratório. Assim, tal sistema deve proporcionar a atuação de uma força oscilatória na passarela, com frequência e amplitude controladas. Os resultados da investigação mostraram que os pedestres tendem a sincronizar-se com a passarela, provocando o efeito lock-in na direção lateral, quando a passarela oscila lateralmente próximo da metade do valor da taxa de passo do pedestre na direção vertical.

The diploma thesis deals with design and assessment of pedestrian and bicycle footbridges across the river Moravia in Olomouc. The main material used in the design is S355 steel. At the beginning of the thesis, two variants are compared, from which one is subsequently selected for a more detailed design and assessment. The main supporting element of the selected variant are two parabolic arcs inclined to one another, on which the coupling of the intermediate bridge is suspended by means of the rods. The construction span is 54m.

The content of this diplom is about design and assesment of a steel footbridge for pedestrians and cyclists across the river Ostravice. In an introduction of the work are compared two possible options of footbridge structures.and then the appropriate one is processed in detail. The chosen variant is made of two parabolic arches tilted to each other on which is suspended deck by suspenders. In a static aspect the main loadbearing beams are two-hinged arches. The bridge deck consists of two steel beams and floor beams which are composited with a reinforced concrete slab. The span length is 80 m and archs camber is 9,12m. The main material of the structural elements is steel S355.