Comunicações

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Neste estudo recorre-se à modelação numérica para a simulação de eventos de galgamento, inundação e erosão costeira em zonas costeiras devido a ocorrência de tempestades. Esta metodologia está a ser estudada para o troço costeiro da Costa da Caparica, na área que compreende toda a extensão da estrutura de defesa aderente, para a tempestade Hércules/Christine. Nesta modelação numérica recorreram-se aos modelos numéricos SWAN e XBeach. Estes modelos foram utilizados para simular 96 h de forçamentos oceanográficos sobre a área de estudo, representando assim a tempestade entre os dias 3 e 7 de janeiro de 2014. Os resultados preliminares apontam para um subestima dos run-up consequência da parametrização do modelo e das características da batimetria considerada.

Nesta comunicação apresentam-se os resultados da aplicação de dois modelos hidromecânicos descontínuos tridimensionais na análise do comportamento da fundação de uma barragem gravidade. Os modelos considerados simulam o comportamento mecânico de forma idêntica mas o comportamento hidráulico é simulado usando abordagens diferentes: i) num dos modelos o escoamento ao longo das descontinuidades do maciço é simulado através de elementos de interface triangulares; ii) no outro modelo admite-se que o escoamento se dá através de canais localizados nas arestas dos elementos de interface triangulares que simulam as diferentes descontinuidades. O estudo efetuado permite confirmar a viabilidade da aplicação de ambos os modelos para a análise do comportamento hidromecânico de fundações de barragens, tendo em consideração a existência da cortina de impermeabilização e do sistema de drenagem. Comparam-se os caudais e pressões obtidas com os dois modelos e os resultados respetivos são utilizados para efetuar análises de estabilidade, recorrendo ao método de redução das resistências.

The use of micromobility in cities has been highly associated with environmental, social, and economic benefits. These sustainability impacts can be achieved by the proper city planning before the implementation of micro vehicles, which can include pilot programs, connection to public transport to promote first-and-last mile trips, curb space management, and safety measurements. Although to better understand the real environmental, social, and economic impacts of micromobility usage in cities, some methodologies need to be used in order to measure them. Thus, this research focuses on an extensive literature review to discuss the most used methodologies to measure the sustainability impacts generated in cities by micromobility. As the results show, to measure the environmental impacts, the Life Cycle Assessment methodology can be used, followed by geospatial analysis and surveys to measure the social impacts, and conversion of health, and time-saving benefits to a monetary unit to measure the economic impacts of micro vehicles.

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The safety of concrete arch dams depends to a large extent on the soundness of the foundation rock mass. The large arch dams presently under design and construction apply very significant loads to their abutments and foundations. The assessment of the foundation stability requires the analysis of the potential failure mechanisms defined by the major rock mass discontinuities and joint sets. For dams located in areas of intense seismic activity, the analysis needs to take into account the potential effects of earthquakes, not only on the concrete arch, but also in the nearby rock discontinuities. The discrete element method is a major numerical tools for discontinuum modelling, allowing the analysis of block systems defined by multiple joint planes. In the paper, the key issues involved in its application to arch dam foundations are reviewed. In particular, the representation of the discontinuities in models intended for failure analysis is discussed. The evaluation of safety factors under static loading is addressed. The framework for seismic analysis of arch dams is also examined, namely the dynamic boundary conditions. Options to analyse the dynamic dam-water interaction and model calibration issues are discussed, based on practical examples.

This research paper aims to contribute to a more sustainable mobility solution by proposing and empirically testing methods to assess the robustness of a network of a multimodal transport system, looking at aspects in the network topology. We hypothesise that the appropriate multilayered and traffic-sensitive modelling of this network can help characterise robustness and further understand the integration of different modalities. We modelled and examined the Lisbon public transports as a multiplex network, allowing us to integrate various modalities and grasp its characteristics and robustness performance. To accomplish this, we evaluate how the network decreases performance by removing nodes and edges. Comparing different failure scenarios, we concluded that we should use slightly different methods for each goal and type of removal (edge vs node). Those who involve recalculating metrics are usually the most effective. However, we identified a specific context where, counter-intuitively, that is not the case. Proposing a novel normalised version of AUC, we were able to compare side by side the robustness of each modality layer, regardless of their size and the whole network. Testing targeting strategies, we also observed that robustness tests needed to remove about half the network nodes to leave all the remaining nodes completely disconnected, and node removals are more effective than eliminating edges in this topology. Lastly, we simulate cascading events such as the breakdown of an entire transportation line. The results of this study allow decision-makers to understand the topological vulnerabilities of a transportation network.

Local scour has been widely identified as one of the primary threats to bridge pier stability. To better understand how the turbulent flow field modified by bridge piers interacts with the bed surface, it is relevant to assess the flow structures that are potentially sufficient to remove the bed material. Thus, the accuracy and measurement quality in estimating the flow field is of primordial importance, mainly in a well-controlled laboratory environment. In the present study, time-averaged velocities and Reynolds shear stresses were measured by using a high-resolution acoustic velocimeter. Due to the highly turbulent nature of the flow, an assessment of the signal acquisition time’s influence on the statistics of turbulent quantities is performed, including the inherent uncertainties regarding the flow field measurement technique. The re-sults showed that the required sampling time for mean and fluctuation velocities, and the lateral Reynolds shear stress, differ by one order of magnitude.

Anomalies in heritage buildings with reinforced concrete structure, related to the cracking of infill masonry walls due to vertical deformations of their structural supporting elements, can have strong negative impact on these buildings, as they usually represent an important cultural and historical value to preserve. These deformations can affect the functionality, aesthetics and the safety of the referred heritage buildings, leading to significant costs associated to repair actions and decrease of their patrimonial value. Hence, a better knowledge of the vertical deformations in heritage buildings with reinforced concrete structure is needed. In this paper, a general description of anomalies related to vertical deformations of the masonry walls and their reinforced concrete supporting elements (beam or slab support) is made. Relevant influencing factors of the wall-support basic behaviour are presented. An analysis of wall-support behaviour related to vertical deformations is carried out, based on the study of the stresses in the constituent elements of wall-support assembly (especially, masonry units, mortar joints and interface wall/support), and of their main types of deformation related with the rigidity of the reinforced concrete support of the wall, and also of the reinforced concrete element (beam or slab) confining at the top of the wall. Serviceability requirements related to the limitation of damage in infill masonry walls, through the control of the deflections of reinforced concrete supports with due consideration of the respective building heritage relevance, are discussed. Finally, general strategies for repair and rehabilitation of building infill masonry walls with anomalies related to vertical deformations of their reinforced concrete supports, as well as for strengthening of these supports, are proposed.

This work aims to determine the exploitable wave energy resource at six potential sites, located in the Azores, Madeira and Sines. For that purpose, the third-generation wave model SWAN is used to estimate the sea-wave conditions over the last 40 years. Boundary conditions of the sea states and wind fields are provided by the climate reanalysis datasets ERA5. Using those results as inputs to the SWAN model, the sea-states were propagated shoreward, in order to estimate and analyse the wave conditions in the regions of interest. By combining the average energy flux per unit-length of wave front and the probability of occurrence of each sea state, the average exploitable annual energy per unit length of wave crest can be computed. The variability of this energy flux is analysed since it is of fundamental importance for the efficiency of the Wave Energy Converters (WEC).