Safety of dams can be evaluated based on the risk analysis methodologies that accounts for estimation of the risks associated to the dam-reservoir system. For this purpose it is important to estimate the probability of load events and probability of failure for several failure modes. The following thesis emphasises on estimation of the probability of one specific failure mode, i.e. “sliding failure” for a concrete gravity dam. The main idea behind this thesis was to analyse the estimation of the probability of sliding failure of an existing dam by obtaining the relationships among the different load events, factors of safety associated to those events and the probability of failure estimated using numerical simulation techniques together with different reliability methods. The analysed dam is taken from theme C of the eleventh ICOLD Benchmark workshop on numerical analysis of dams. The thesis covers the methodology for estimating the probability of failure of a given concrete gravity dam with five water levels, considering the sliding failure mode along the dam-foundation interface along with the estimation of factors of safety for each water level and with two different drainage conditions. First order second moment Taylor’s Series Approximation is being used as Level 2 reliability method and Monte Carlo simulation as Level 3 reliability method to estimate the probability of failure against sliding of the dam. Conclusions are drawn in the end by comparing the results obtained from factor of safety estimation and probability of failure for each water level and drainage condition, followed by suggestions for further research in the context of sliding stability of concrete dams.

Sistemas estruturais constituídos por perfis de aço são, em geral, dimensionados de uma forma \"indireta\", isto é, cada componente é analisado e verificado segundo suas capacidades teóricas individualmente, normalmente associando-se condições de extremidade e comprimentos teóricos para cada barra de modo a aproximar a sua capacidade portante sob a condição real. Contudo, importantes efeitos como a transmissão do empenamento entre as barras devido à torção e/ou distorção, as restrições localizadas impostas por sistemas de contraventamento ou componentes diversos, e também a compatibilidade de deslocamentos locais/globais entre barras conectadas não alinhadas entre si, são desconsiderados, uma vez que o estudo de tais efeitos envolve, normalmente, custosos trabalhos de modelagem através de elementos finitos de casca (e/ou sólidos), soluções numéricas complexas e demoradas, e/ou estudos experimentais caros e trabalhosos. Neste contexto, alguns recentes trabalhos apontam para um vasto campo de aplicações das inovadoras potencialidades da Teoria Generalizada de Vigas (GBT), permitindo, em particular, a análise de sistemas estruturais que consideram os diversos efeitos provocados por condições de apoio arbitrárias, diferentes posições do carregamento e efeitos decorrentes das ligações entre as barras. Contudo, apesar de tais recursos ampliarem as aplicações da GBT na análise de estabilidade de sistemas estruturais, apenas um conjunto limitado de problemas pode ser atendido, especialmente quanto às ligações entre as barras. Os recentes trabalhos envolvendo a aplicação da GBT para a análise de estabilidade de pórticos metálicos dedicaram-se ao estudo de alguns casos específicos de ligações rígidas, isto é, assumem a hipótese de transferência completa dos deslocamentos generalizados entre as barras. Assim, uma vez que a rigidez de tais ligações pode ser responsável por mudanças significativas no comportamento do sistema estrutural em questão, este trabalho procura fornecer uma solução capaz de considerar a semirrigidez das ligações metálicas associada aos parâmetros modais típicos da GBT. Além disso, dada a possibilidade de ampliar os tipos de ligações analisadas por meio da GBT, incluindo as configurações mais comumente utilizadas na prática, apresentam-se novos conjuntos de relações cinemáticas desenvolvidas para tal, assim como as referidas validações, que são realizadas por meio de análises utilizando o programa computacional ANSYS®. / Steel structural systems are usually associated with an \"indirect approach\", i.e., each component of the respective structure is analysed and verified according to its theoretical individual capacity. Normally, in order to approximate the real behaviour of the structural system, specific support conditions and effective length concepts are used to analyse each structural member separately. However, some important effects are disregarded in this procedure, like the warping transmission at frame joints (due to torsion and/or distortion), or those stemming from localized supports associated with bracing systems, as well as the local/global displacements compatibility of the cross-section walls at the joint region. Additionally, studies considering the above mentioned effects involves rather complicated and time-consuming numerical analyses using shell and/or solid finite elements, and/or expensive experimental investigation. On the other hand, some recent studies revealed a large field for application of the Generalized Beam Theory (GBT) in the context of the stability, first and second order analyses of structural systems, considering, particularly, the effects caused by arbitrary support conditions, different load positions, and the effects caused by connections between members. Nonetheless, all the recent works applying GBT for stability analysis of steel frames are focused on some specific cases of rigid connections, i.e., they assume the full transfer of the generalized displacements between the non-aligned members. Thus, given the well-known fact that the rigidity of connections may lead to considerable changes of the structural behaviour of steel structural systems, this work deals with the development of a solution to incorporate the semi-rigidity of the steel frame connections to the modal parameters of the GBT. Furthermore, given the possibility to expand the connection types analysed by means of GBT, including the most commonly used configurations adopted in practice, it is presented the related new kinematic relations developed, as well as the validation studies carried out in the software ANSYS®.

The traffic engineering community currently faces the advent of a new generation of Intelligent Transportation Systems (ITS), known as cooperative systems. More specifically, the recent developments of connected and autonomous vehicles, i.e. cooperative vehicles, are expected to cause a societal shift, changing the way people commute on a daily basis and relate to transport in general. The research presented in this dissertation is motivated by the need for proper understanding of the possible inputs of cooperative vehicles in a traffic stream. Beyond legal aspects regarding the introduction of such vehicles and considerations on standardization and harmonization of the communication norms, the research focuses on the use of communication for highway traffic flow homogenization. In particular, the selected approach for the introduction of cooperation inherits from the theory of traffic flow and the recent developments of microscopic traffic models. Cooperation can first be introduced as a form of multi-anticipation, which can either come from drivers' behaviors or from communication. A mathematical framework for investigating the impact of perturbations into a steady-state traffic is proposed for the class of time continuous car-following models. Linear stability analyses are refined for forward and backward multi-anticipation, exploring the underlying importance of considering upstream information. The linear stability analyses for all wavelengths can be deepened by the mean of the graphical root locus analysis, which enables comparisons and design of strategies of cooperation. The positive influence of bilateral cooperation and of added linear control terms are highlighted. Weakly non-linear analyses are also performed, and the equations of solitary waves appearing at the frontier of the instability domain are obtained. A simple condition over the partial derivatives of the dynamical system is found to determine the acceleration regime of the leading edge of the travelling wave. Following these analytical results, one aim is to simulate a realistic traffic thereby reproducing the driving behavior variability. A Next Generation Simulation trajectory dataset is used to calibrate three continuous car-following models. A methodology involving data filtering, robust calibration, parameters estimation and sampling of realistic parameters is detailed, and allows realistic traffic with stop-and-go waves appearances to be replicated. Based on these simulated trajectories, previous analytical results are confirmed, and the growing perturbations are removed for various coverage rates of cooperative vehicles and adequately tuned cooperative strategies. Finally the issue of information reliability is assessed for a mixed fleet of cooperative and non-cooperative vehicles. The modeling choice consists in building a three layers multi-agent framework that enables the following properties to be defined: the physical behavior of vehicles, the communication possibilities, and the trust each vehicle -or agent- has in another vehicle information or in itself. The investigation of trust and communication rules allow the model to deal with high rates of disturbed cooperative vehicles sensors and to learn in real time the quality of the sent and received information. It is demonstrated that appropriate communication and trust rules sensibly increase the robustness of the network to perturbations coming from exchanges of unreliable information.

Sistemas estruturais constituídos por perfis de aço são, em geral, dimensionados de uma forma \"indireta\", isto é, cada componente é analisado e verificado segundo suas capacidades teóricas individualmente, normalmente associando-se condições de extremidade e comprimentos teóricos para cada barra de modo a aproximar a sua capacidade portante sob a condição real. Contudo, importantes efeitos como a transmissão do empenamento entre as barras devido à torção e/ou distorção, as restrições localizadas impostas por sistemas de contraventamento ou componentes diversos, e também a compatibilidade de deslocamentos locais/globais entre barras conectadas não alinhadas entre si, são desconsiderados, uma vez que o estudo de tais efeitos envolve, normalmente, custosos trabalhos de modelagem através de elementos finitos de casca (e/ou sólidos), soluções numéricas complexas e demoradas, e/ou estudos experimentais caros e trabalhosos. Neste contexto, alguns recentes trabalhos apontam para um vasto campo de aplicações das inovadoras potencialidades da Teoria Generalizada de Vigas (GBT), permitindo, em particular, a análise de sistemas estruturais que consideram os diversos efeitos provocados por condições de apoio arbitrárias, diferentes posições do carregamento e efeitos decorrentes das ligações entre as barras. Contudo, apesar de tais recursos ampliarem as aplicações da GBT na análise de estabilidade de sistemas estruturais, apenas um conjunto limitado de problemas pode ser atendido, especialmente quanto às ligações entre as barras. Os recentes trabalhos envolvendo a aplicação da GBT para a análise de estabilidade de pórticos metálicos dedicaram-se ao estudo de alguns casos específicos de ligações rígidas, isto é, assumem a hipótese de transferência completa dos deslocamentos generalizados entre as barras. Assim, uma vez que a rigidez de tais ligações pode ser responsável por mudanças significativas no comportamento do sistema estrutural em questão, este trabalho procura fornecer uma solução capaz de considerar a semirrigidez das ligações metálicas associada aos parâmetros modais típicos da GBT. Além disso, dada a possibilidade de ampliar os tipos de ligações analisadas por meio da GBT, incluindo as configurações mais comumente utilizadas na prática, apresentam-se novos conjuntos de relações cinemáticas desenvolvidas para tal, assim como as referidas validações, que são realizadas por meio de análises utilizando o programa computacional ANSYS®. / Steel structural systems are usually associated with an \"indirect approach\", i.e., each component of the respective structure is analysed and verified according to its theoretical individual capacity. Normally, in order to approximate the real behaviour of the structural system, specific support conditions and effective length concepts are used to analyse each structural member separately. However, some important effects are disregarded in this procedure, like the warping transmission at frame joints (due to torsion and/or distortion), or those stemming from localized supports associated with bracing systems, as well as the local/global displacements compatibility of the cross-section walls at the joint region. Additionally, studies considering the above mentioned effects involves rather complicated and time-consuming numerical analyses using shell and/or solid finite elements, and/or expensive experimental investigation. On the other hand, some recent studies revealed a large field for application of the Generalized Beam Theory (GBT) in the context of the stability, first and second order analyses of structural systems, considering, particularly, the effects caused by arbitrary support conditions, different load positions, and the effects caused by connections between members. Nonetheless, all the recent works applying GBT for stability analysis of steel frames are focused on some specific cases of rigid connections, i.e., they assume the full transfer of the generalized displacements between the non-aligned members. Thus, given the well-known fact that the rigidity of connections may lead to considerable changes of the structural behaviour of steel structural systems, this work deals with the development of a solution to incorporate the semi-rigidity of the steel frame connections to the modal parameters of the GBT. Furthermore, given the possibility to expand the connection types analysed by means of GBT, including the most commonly used configurations adopted in practice, it is presented the related new kinematic relations developed, as well as the validation studies carried out in the software ANSYS®.

Dams are designed and assessed based on traditional factor of safety methodology. Several drawbacks of this approach exist; for example varying failure probability for structures where the factor of safety is the same. This traditional factor of safety methodology imposes conservative assumptions in terms of both design and analysis. A probability-based analysis has been suggested to account for the omission of uncertainties and provide a less conservative analysis (Westberg & Johansson, 2014). Through the stability analyses of three existing dam structures, a minimum level of reliability or maximum failure probability may be calculated with the ultimate goal of defining a target safety index (β-target) for buttress and gravity dams. These analyses shall in turn contribute to the formulation of a probability-based guideline for the design and assessment of Swedish concrete dams. This probability-based guideline shall be known as the ‘Probabilistic Model Code for Concrete Dams.’ The calculations carried out in this study adhere to the methodologies and specifications set out in the preliminary draft of the Probabilistic Model Code for Concrete Dams. These methodologies encompass analyses within two dominating failure modes for concrete dams; sliding stability and overturning stability. Various load combinations have been modelled for each dam structure to account for the probabilistic failure of each dam under commonly occurring circumstances. A parametric study has been carried out in order to provide insight into the contribution that existing rock bolts provide to the stability of each dam. Furthermore, a study has been carried out into the existence of a persistent rock joint or failure plane in the rock foundation and the effects its presence would have on the sliding stability of a dam. Finally a discussion had been carried out in order to provide suggestions into the formulation of a target safety index through the data envisaged by our analyses for the design and assessment of Swedish concrete dams.