Este trabalho utiliza uma metodologia simplificada de análise dinâmica para o estudo das vibrações em pontes ferroviárias, produzidas pela passagem de um trem de alta velocidade, associadas à presença de irregularidades nos trilhos. Iniciou-se o estudo a partir de um modelo do veículo composto por quinze graus de liberdade, referentes aos deslocamentos verticais e horizontais transversais, e rotações em torno dos eixos longitudinal, transversal e vertical. Os modelos dinâmicos do trem e da ponte foram tratados de forma desacoplada, sendo conectados pelas forças de interação trem-ponte. Desta forma, foram calculados os carregamentos provenientes da modelação dinâmica do trem, adotando-se inicialmente a hipótese de tabuleiro rígido e indeslocável e, ainda, considerando-se a presença de irregularidades geométricas nos trilhos no plano vertical. Neste trabalho, foi considerado um estudo de caso utilizando-se o modelo veicular Alfa Pendular, avaliando-se a resposta dinâmica do trem e da estrutura, considerando o efeito das irregularidades geométricas nos trilhos, bem como a presença do lastro. As forças de interação obtidas da modelagem do veículo foram aplicadas em um modelo estrutural de alta hierarquia da ponte, dividido em elementos finitos de casca, sendo que em cada nó do modelo da ponte foram especificados os esforços obtidos da análise dinâmica do veículo. Para representar a passagem do comboio sobre a ponte, foram utilizadas funções que descrevem as forças de interação trem-ponte em cada nó do modelo da ponte, em cada intervalo de tempo, até que todo o trem tenha percorrido o comprimento da ponte. A consideração de tabuleiro rígido indeslocável foi corrigida por meio de um processo iterativo, de forma que os deslocamentos do tabuleiro obtidos para a primeira determinação dos esforços de interação foram somados às irregularidades do trilho (excitação de suporte aplicada nas rodas do trem). Com isso, foi possível identificar a resposta dinâmica proveniente da carga em movimento e das irregularidades geométricas nos trilhos, avaliando o conforto dos passageiros no interior do vagão. Por fim, realizou-se uma análise de distribuição estatística para avaliar a probabilidade de se ultrapassar os limites estabelecidos pelo Eurocode. / This thesis resorts to a simplified methodology of dynamic analysis for the study of vibrations in railway bridges, produced by the passage of a high speed train, associated to the presence of irregularities in the rails. The study started from a vehicle model composed of fifteen degrees of freedom, namely, vertical and lateral displacements, and rotations about the longitudinal, lateral and vertical axes. The dynamic models of the train and the bridge were treated as uncoupled, yet being bound by the interaction train-bridge forces. Thus, the loads from the dynamic model of the train were calculated, adopting initially the hypothesis of rigid and fixed deck and also, considering the presence of geometric irregularities in the vertical track plane. In this work, we considered a case study using the Alfa Pendular vehicle model, evaluating the dynamic response of the train and the structure, considering the effect of the geometric irregularities at the tracks, as well as the presence of the ballast. The interaction forces obtained from the model of the vehicle were applied in a high hierarchy structural model of the bridge, divided into shell finite elements, specifying the forces obtained from the dynamic analysis of the vehicle at each node of the bridge model. To represent the train passage on the bridge, functions were used to describe the bridge-train interaction forces at each node of the bridge model at each time interval, until the entire train had travelled the bridge length. The consideration of rigid and fixed deck was corrected by means of an iterative process, so that the deck displacements obtained for a first determination of the interaction forces were added to the rail irregularities (excitation applied to the train wheels). Thus, it was possible to identify the dynamic response caused both by the moving loading and the geometrical irregularities of the tracks, evaluating the comfort of the passengers inside the wagon. Finally, a reliability study was carried out to evaluate the probability of exceeding the limits established by Eurocode.

Este trabalho trata do problema das vibrações induzidas em estruturas de concreto de pontes ferroviárias, produzidas pela passagem da composição de um TUE (Trem Unidade Elétrico) típico. Partiu-se de um modelo do veículo com nove graus de liberdade, referentes aos deslocamentos verticais e rotações em torno dos eixos longitudinal e transversal, introduzindo-se os graus de liberdade de deslocamentos transversais horizontais e rotações em torno do eixo vertical. Foram calculados os carregamentos provenientes do trem modelado sobre tabuleiro rígido indeslocável, considerando as irregularidades geométricas apresentadas nos trilhos e nas rodas, sendo diferenciada para cada linha de trilho. Estes carregamentos foram condensados estaticamente e aplicados em um modelo estrutural simplificado (unifilar) de uma ponte de seção celular, visando a identificar a resposta dinâmica proveniente das irregularidades geométricas. Finalmente, avalia-se a amplificação dinâmica, a qual é comparada com o valor do coeficiente de impacto prescrito na norma brasileira para projeto de pontes ferroviárias. / This dissertation discusses the problem of induced vibrations in concrete structures of railway bridges, produced by the passing of a typical composition of electric urban trains. It started from a vehicle model with nine degree-of-freedom, related to vertical displacements and rotations around the longitudinal and transverse axes, introducing the degrees-of-freedom of horizontal transverse displacements and rotations around the vertical axis. The trains loads applied to the bridge deck were evaluated, assuming initially a rigid structure under the board, considering the geometric irregularities present in rails and wheels and different for each rail line. These loads were statically reduced to the vehicle center of mass and applied to a simplified bridge structural model, aiming at identifying the dynamic response due to geometric irregularities. Finally the dynamic amplification is evaluated and compared to the value of the impact coefficient prescribed by the Brazilian Standards for design of railway bridges.

Este trabalho utiliza uma metodologia simplificada de análise dinâmica para o estudo das vibrações em pontes ferroviárias, produzidas pela passagem de um trem de alta velocidade, associadas à presença de irregularidades nos trilhos. Iniciou-se o estudo a partir de um modelo do veículo composto por quinze graus de liberdade, referentes aos deslocamentos verticais e horizontais transversais, e rotações em torno dos eixos longitudinal, transversal e vertical. Os modelos dinâmicos do trem e da ponte foram tratados de forma desacoplada, sendo conectados pelas forças de interação trem-ponte. Desta forma, foram calculados os carregamentos provenientes da modelação dinâmica do trem, adotando-se inicialmente a hipótese de tabuleiro rígido e indeslocável e, ainda, considerando-se a presença de irregularidades geométricas nos trilhos no plano vertical. Neste trabalho, foi considerado um estudo de caso utilizando-se o modelo veicular Alfa Pendular, avaliando-se a resposta dinâmica do trem e da estrutura, considerando o efeito das irregularidades geométricas nos trilhos, bem como a presença do lastro. As forças de interação obtidas da modelagem do veículo foram aplicadas em um modelo estrutural de alta hierarquia da ponte, dividido em elementos finitos de casca, sendo que em cada nó do modelo da ponte foram especificados os esforços obtidos da análise dinâmica do veículo. Para representar a passagem do comboio sobre a ponte, foram utilizadas funções que descrevem as forças de interação trem-ponte em cada nó do modelo da ponte, em cada intervalo de tempo, até que todo o trem tenha percorrido o comprimento da ponte. A consideração de tabuleiro rígido indeslocável foi corrigida por meio de um processo iterativo, de forma que os deslocamentos do tabuleiro obtidos para a primeira determinação dos esforços de interação foram somados às irregularidades do trilho (excitação de suporte aplicada nas rodas do trem). Com isso, foi possível identificar a resposta dinâmica proveniente da carga em movimento e das irregularidades geométricas nos trilhos, avaliando o conforto dos passageiros no interior do vagão. Por fim, realizou-se uma análise de distribuição estatística para avaliar a probabilidade de se ultrapassar os limites estabelecidos pelo Eurocode. / This thesis resorts to a simplified methodology of dynamic analysis for the study of vibrations in railway bridges, produced by the passage of a high speed train, associated to the presence of irregularities in the rails. The study started from a vehicle model composed of fifteen degrees of freedom, namely, vertical and lateral displacements, and rotations about the longitudinal, lateral and vertical axes. The dynamic models of the train and the bridge were treated as uncoupled, yet being bound by the interaction train-bridge forces. Thus, the loads from the dynamic model of the train were calculated, adopting initially the hypothesis of rigid and fixed deck and also, considering the presence of geometric irregularities in the vertical track plane. In this work, we considered a case study using the Alfa Pendular vehicle model, evaluating the dynamic response of the train and the structure, considering the effect of the geometric irregularities at the tracks, as well as the presence of the ballast. The interaction forces obtained from the model of the vehicle were applied in a high hierarchy structural model of the bridge, divided into shell finite elements, specifying the forces obtained from the dynamic analysis of the vehicle at each node of the bridge model. To represent the train passage on the bridge, functions were used to describe the bridge-train interaction forces at each node of the bridge model at each time interval, until the entire train had travelled the bridge length. The consideration of rigid and fixed deck was corrected by means of an iterative process, so that the deck displacements obtained for a first determination of the interaction forces were added to the rail irregularities (excitation applied to the train wheels). Thus, it was possible to identify the dynamic response caused both by the moving loading and the geometrical irregularities of the tracks, evaluating the comfort of the passengers inside the wagon. Finally, a reliability study was carried out to evaluate the probability of exceeding the limits established by Eurocode.

Este trabalho trata do problema das vibrações induzidas em estruturas de concreto de pontes ferroviárias, produzidas pela passagem da composição de um TUE (Trem Unidade Elétrico) típico. Partiu-se de um modelo do veículo com nove graus de liberdade, referentes aos deslocamentos verticais e rotações em torno dos eixos longitudinal e transversal, introduzindo-se os graus de liberdade de deslocamentos transversais horizontais e rotações em torno do eixo vertical. Foram calculados os carregamentos provenientes do trem modelado sobre tabuleiro rígido indeslocável, considerando as irregularidades geométricas apresentadas nos trilhos e nas rodas, sendo diferenciada para cada linha de trilho. Estes carregamentos foram condensados estaticamente e aplicados em um modelo estrutural simplificado (unifilar) de uma ponte de seção celular, visando a identificar a resposta dinâmica proveniente das irregularidades geométricas. Finalmente, avalia-se a amplificação dinâmica, a qual é comparada com o valor do coeficiente de impacto prescrito na norma brasileira para projeto de pontes ferroviárias. / This dissertation discusses the problem of induced vibrations in concrete structures of railway bridges, produced by the passing of a typical composition of electric urban trains. It started from a vehicle model with nine degree-of-freedom, related to vertical displacements and rotations around the longitudinal and transverse axes, introducing the degrees-of-freedom of horizontal transverse displacements and rotations around the vertical axis. The trains loads applied to the bridge deck were evaluated, assuming initially a rigid structure under the board, considering the geometric irregularities present in rails and wheels and different for each rail line. These loads were statically reduced to the vehicle center of mass and applied to a simplified bridge structural model, aiming at identifying the dynamic response due to geometric irregularities. Finally the dynamic amplification is evaluated and compared to the value of the impact coefficient prescribed by the Brazilian Standards for design of railway bridges.

To deal with a rapid development of high-speed trains and high-speed railways, constant improvement of the railway infrastructure is necessary and engineers are continuously facing challenges in order to design efficient and optimized structures. Nowadays, more and more railway bridges are built and thus, they require the engineers’ attention both regarding their design and their maintenance. A comprehensive knowledge of the infrastructures and the trains is crucial: their behaviours need to be well known. However, today, the ballast - the granular material disposed on the track and on which the rails lie – is not well known and its effect in dynamic analyses are rarely accounted for. Engineers are still investigating the role played by the ballast in the dynamic behaviour of bridges.  This master thesis aims at quantifying the influence of the ballast on the dynamic properties of a bridge. Is the ballast just an additional mass on the structure or does it introduce any additional stiffness? Thus, this project investigates different alternatives and parameters to propose a realistic and reliable model for the ballast superstructure and the track. For the purpose of this study, a simply supported steel truss bridge located in Poland is studied. The bridge was excited by a harmonic force and the interesting point regarding the experiments is that acceleration measurements were collected before and after the ballasted track setting up on the bridge deck. Then, these data are processed through MATLAB in order to obtain the natural frequencies of the bridge at two different times during its construction. The determined natural frequencies for the un-ballasted case are then compared with analytical values obtained with a 3D finite element model implemented in the software LUSAS. This step aims at calibrating the un-ballasted finite element model so that the bridge is represented as realistically as possible. Once it has been done, a model both for the ballast and the track is proposed using solid elements for the ballast superstructure and beam elements for the rails, the guard rails and the sleepers. Different parameters influencing the natural frequencies and modes shapes of the bridge are testing and it appears that the ballast introduces an additional stiffness through a bending stiffness in the ballast and a change in the support conditions. Finally, the contribution of these parameters is assessed and discussed: the stiffness of the ballast increases the stiffness of the bridge by more than 20% for the 2nd vertical bending vibration mode and the support conditions increase the bridge’s stiffness by more than 15% and 30% respectively for the 1stvertical bending the 1st torsional vibration modes.

The global understanding that natural resources and non renewable energy sources are not inexhaustible has been growing lately together with the increase of conscientiousness on the consequences that our demanding way of life has on the environment. Global warming, ozone layer depletion, the greenhouse effect or the acid rain, are some of these consequences, which may reach catastrophic levels if nothing is done to emend the actual situation. Lately, society is beginning to see sustainability not only as a needed requirement but as a distinctive value which has to be pursued by the different areas of society involved and responsible for a sustainable development such as public administration and companies, engineers and researchers. As a fundamental part of society, infrastructures have utmost importance in sustainable development. Even more when it comes to rail transport infrastructure, given the important role of rail transport in the development of a sustainable society. That is why engineers should make an effort to use all the tools available to choose the best structural design, which not only meets structural requirements, but has also a good performance for the environment. To do so, engineers must focus on using renewable sources or energy and materials, increasing the life of the existing infrastructures, making them more durable. When it comes to railway bridges, it is preferable to reuse and adapt existing structures than tear them down to build new ones. In this line, environmental assessment methodologies provide an incredibly valuable tool for help decision-makers and engineers to identify and select the best alternative design regarding environmental issues. Therefore, it is important to count on a common basis and established criteria together with a systematic methodology in order to obtain reliable results to compare alternatives and make the right decisions. However, nowadays, there exists very little guidance to perform this kind of analysis, and an extensive variety of databases and methodologies non standardized, which leads to uncertainties when it comes to evaluate and compare the obtained results. This thesis means to be a good guide for engineers, when performing a Life Cycle Assessment of a railway bridge, and to become a useful tool to compare several alternatives to identify the best option relating the environmental burdens involved. With this purpose, in order to know the state of the art of LCA methodology, it has been studied a wide range of existing literature and previous studies performed to analyze bridges and building materials. Finally, it has been developed an own methodology based on all the research done before, and implemented in an Excel application program based on Visual Basic macros, which means to be easy to use with a simple user interface, and to provide reliable results. The application is useful for assessing, repair or improving existing bridges, where the amounts of materials and energy are known, but can also be helpful in the design phase to compare different alternatives. It also allows using different weighting methodologies according to several reference sources depending on the case of study. The application is tested by carrying out a Life Cycle Assessment of a Spanish railway bridge located in the city center of Vitoria-Gasteiz, evaluating the different structures that conform the bridge system thorough all the stages of its life cycle identifying the most contributive parameters to the environmental impacts. The study was carried out over a 100 year time horizon. In the case of performing the LCA of this particular bridge, the contribution of the whole bridge is taken into consideration. When comparing two different bridges, the application has the option to compare them in the same basis, dividing by length and width of the bridge, which is a helpful tool if both bridges are not the same size. All stages of the life cycle were considered: the material stage, construction, the use and maintenance stage, and the end of life. The material stage includes the raw material extraction, production and distribution. The construction stage accounts the diesel, electricity and water consumption during construction activities. The use and maintenance stage covers the reparation and replacing operations. And the end of life covers several scenarios. In this case of study, in order not to interrupt the rail traffic, the bridge was constructed parallel to its final location, and then moved into the right place with hydraulic jacks. This leads to an important auxiliary structure with its own foundations, which has a significant contribution to the overall environmental impact. The scenario chosen for the end of life was based on similar actuation in other constructions in the proximities of the bridge, as the bridge is already in use. These assumptions were to recycle 70 % of the concrete and 90 % of the steel; all the wood used for formwork was disposed as landfill. The results obtained, weighted according to the US Environmental Protection Agency, shows that the main contributor to the environmental impacts is the material phase, with the 64 % of the total weighted results with concrete and steel production as principal factors, followed by timber production. These processes account great amounts of CO 2emissions, which makes essential to focus on reducing the impact of the material processes by optimizing the processes but mainly by reusing materials from other constructions as much as it may be possible. The maintenance activities have some importance due to the frequency of the track replacement, assumed to be once every 25 years. While construction does not imply great burdens for the environment, the end of life causes the 33 % of the overall bridge impact. This is due to the timber formwork disposal as landfill and to a lesser extent because of the recycling of the steel. The timber disposal increases widely the eutrophication effect, and will be easy to be reused in further constructions. Regarding the different parts of the bridge structure, the auxiliary structure has an important contribution with the 61 % of the overall weighted impact. As it is a concrete bridge, both the substructure and superstructure has similar contribution. The substructure has a slightly higher impact with the 21 % and the superstructure the 15 %. Rail structure and transport have very little contribution.

No description available.

To deal with an increasing demand in transportation, trains are made longer and faster. Higher speeds imply higher impacts on bridges. Therefore, structures have to be designed to resist these new constraints. The Eurocode (2002) introduced additional checks for the design of high-speed railway bridges. Among them, the maximum vertical deck acceleration criterion often determines alone the design of the structure. Tests on shake table brought to the conclusion that vertical bridge deck acceleration should never exceed 3.5 m/s2 for ballasted tracks. This master thesis investigates the optimization of cross section parameters of single-track simply supported and double-span bridges based on the limit of the maximum vertical deck acceleration criterion. The first natural frequency is considered as a proof of the feasibility of the structure. The optimization is carried out through MATLAB for both types of bridges. The deck acceleration of simply supported bridges is analytically calculated using the Train Signature (ERRI D214 1999) in MATLAB. The dynamic calculations of double-span bridges are implemented through the finite element software ABAQUS. The implemented programs have been verified by comparison to values of simple cases found in the literature. Structures are tested under the influence of the ten HSLM-A trains of the Eurocode running at speeds between 150 km/h and 350 km/h. Optimization algorithms are presented and compared in this study but their applicability in such context is questioned. Indeed, as the problem contains several suitable minima, the algorithms, which end in one solution, are not adapted. To overtake this difficulty, a scanning of the interesting zone is advised. However, the latter is very time consuming, even more if the finite element analysis is used. Suggestions to decrease analysis time are presented in this report. Single span composite bridges with a span longer than 20 m appeared to be impossible to optimize within the objectives defined in this work (i.e. considering limits of deck acceleration and first natural frequency), which draws doubts about their suitability for high-speed railways. Nevertheless, simply supported bridges made of concrete seem more adapted for high-speed railways and their optimized parameters are presented in this work. Optimized parameters for double-span concrete bridges are also presented.

Thesis rises from an actual needs to make standard of practice for assessment an existing arch railway masonry bridges on the basis of condition long term monitoring. Bridge assessment is a part of any inspection, especially in case of doubts arising during inspections due to heavy defects, increase of axle load or increase of train frequency, which may influence the structural safety, traffic safety or durability of a bridge. There are possibilities for utilization of monitoring results for assessment in case of investigation data absece. An important option is assessment based on satisfactory past performance by ČSN ISO 13822, chapter 8.

Environmental awareness has strongly increased these last years, especially in the developed countries where societies have become increasingly preoccupied by the natural resource depletion and environmental degradation. At the same time, the increasing mass transportation demand throughout the European Union requires the development of new infrastructures. Life Cycle Assessment is increasingly used to provide environmental information for decision-makers, when a choice is to be made about the transportation mode to be implemented on a given route. In a life-cycle perspective, not only the environmental pressure of the operation of vehicles but also the burden from the infrastructure, in particular bridges as key links of the road and railway networks, has to be assessed when comparing transportation modes. Based on an extensive literature review, a simplified quantitative LCA is implemented in order to compare the environmental performance of two railway bridge designs. It is meant to be useful at an early stage in the design process, when no detailed information about the bridge is available, and when rough environmental estimations are needed. The Excel based model covers the entire life-cycle of the bridge, from raw material extraction to construction materials recycling and disposal. Various assumptions and omissions are made to narrow the scope of the analysis. For instance, processes that are found insignificant in the literature are omitted, and only a limited set of relevant emissions and impacts to the environment is considered. The model provides fully transparent results at the inventory and impact assessment level. The streamlined approach is tested by comparing the environmental burden throughout the life-cycle of a steel-concrete composite railway bridge on a single span, equipped with either a ballasted or a fixed concrete single track. The results show that the environmental impacts of the fixed track alternative are lower than that of the ballasted track alternative, for every impact categories. In a sustainable development perspective, it would thus have been preferable to install a fixed track over the bridge to reduce its overall impact on the environment by about 77%. The raw material phase is found decisive in the life-cycle of both alternatives. The frequency of the replacement of the track is identified as a key environmental parameter, since the road traffic emissions during bridge closure nearly overwhelmed the other life-cycle stages.