ISEP - Departamento de Engenharia Civil
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- 1º Ciclo de Palestras de Engenharia CivilPublication . Departamento de Engenharia Civil; Lopes, Duarte Barroso; Fontão, Eunice VilaverdeRealizou-se o I Ciclo de Palestras no Departamento de Engenharia Civil do Instituto Superior de Engenharia do Porto, sobre os seguintes temas: Revestimentos em Edifícios - dia 17 de Outubro de 2001 Zonas Costeiras - dia 14 de Novembro de 2001 Betão Reforçado com Fibras - dia 12 de Dezembro de 201 De que resultaram os textos das comunicações agora compilados. Na escolha dos temas considerou-se a sua actualidade e o facto de completarem os assuntos das aulas do curso de Engenharia Civil. No futuro prevê-se a realização de novos ciclos com temas diversos proporcionando a divulgação de conhecimentos e criando um espaço de diálogo com técnicos e investigadores. Não deve deixar de se referir, que estas palestras reflectem o empenho de docentes do DEC na actualização de conhecimentos em áreas científicas de elevado potencial e interesse para uma escola de engenharia de grandes tradições.
- 1º Simpósio Engenharia Civil (SEC2021): Livro de AtasPublication . Ribeiro, Diogo; Portela, Maria da Fátima; Oliveira, Maria Rosário; Santos, Ricardo; Neto, TeresaAbstract O Instituto Superior de Engenharia do Porto, em parceria com as Escolas do Ensino Superior Universitário e Politécnico, organizou o 1º Simpósio de Engenharia Civil (SEC 2021), que decorreu no dia 19 de maio de 2021, em formato híbrido. O evento teve como principal objetivo a apresentação dos resultados dos trabalhos académicos de final de curso dos estudantes de Licenciaturas e Mestrados em Engenharia Civil, realizados no período entre 2018 e 2020. Além disso, pretendeu-se incentivar a troca de experiências, reflexão e discussão entre estudantes finalistas/recém-diplomados e as entidades empregadoras. Pretendeu-se ainda com este evento promover uma forte mobilização e participação de estudantes na área da Engenharia Civil de todas as Escolas do Ensino Superior Universitário e Politécnico, e deste modo, dar visibilidade aos melhores trabalhos desenvolvidos em ambiente académico ou por meio de parcerias entre a academia e a indústria. Possibilitou-se aos representantes das empresas conhecer de perto os trabalhos desenvolvidos no âmbito dos 1º e 2º ciclos de estudos de Engenharia Civil. No programa do evento participaram dois oradores convidados, com vasta experiência académica e de investigação em domínios da Engenharia Civil, um do lado da academia e outro do lado das empresas. Estes oradores partilharam a sua visão acerca das inovações e tecnologias emergentes nos seus domínios de conhecimento e que no futuro poderão ter impacto nas atividades dos profissionais de Engenharia Civil. No evento estiveram presentes 28 Escolas de Engenharia de Portugal, representadas por 32 membros que constituíram a Comissão Organizadora e 28 membros que integraram a Comissão Científica.
- Analysis of Nonlinear Wave Parameters on Ofir Sandy Beach (NW Portugal)Publication . Abreu, Tiago; Silva, Paulo A.; Baptista, Paulo; Pais-Barbosa, Joaquim; Fernández-Fernández, Sandra; Ferreira, Caroline; Matos, JoãoThe characterization of wave transformation processes in the nearshore is of paramount importance when it comes to assessing storm and flooding impacts, sediment transportation and deposition, harbors safety or design of coastal protective structures. This study analyzes nonlinear wave parameters on Ofir sandy beach. This beach is located along the northwest Portuguese coast which is a highly energetic coast exposed to waves generated far away in the Atlantic Ocean. Despite the existence of rocky outcrops in the nearshore and intertidal zones at the study site, reducing the wave energy that reaches the beach, the study site exhibits pronounced erosive processes. Field observations of six near-bottom pressure records collected at the intertidal zone help to characterize the evolution of wave nonlinearities which are directly associated with sediment transport mechanisms. Data results show that there is an interrelation between the characteristics of the waves and the local morphology. It is also possible to ascertain, more clearly, the level of asymmetry present in the waves propagated at different depths, contributing to a better understanding of the local morpho-hydrodynamics.
- Analysis of the Out-Of-Plane Seismic Behavior of Unreinforced Masonry: A Literature ReviewPublication . Ferreira, Tiago Miguel; Costa, Alexandre A.; Costa, AníbalAlthough the issue of the out-of-plane response of unreinforced masonry structures under earthquake excitation is well known with consensus among the research community, this issue is simultaneously one of the more complex and most neglected areas on the seismic assessment of existing buildings. Nonetheless, its characterization should be found on the solid knowledge of the phenomenon and on the complete understanding of methodologies currently used to describe it. Based on this assumption, this article presents a general framework on the issue of the out-of-plane performance of unreinforced masonry structures, beginning with a brief introduction to the topic, followed by a compact state of art in which the principal methodologies proposed to assess the out-of-plane behavior of unreinforced masonry structures are presented. Different analytical approaches are presented, namely force and displacement-based, complemented with the presentation of existing numerical tools for the purpose presented above. Moreover, the most relevant experimental campaigns carried out in order to reproduce the phenomenon are reviewed and briefly discussed.
- Calibration of the numerical model of a freight railway vehicle based on experimental modal parametersPublication . Ribeiro, Diogo; Bragança, C.; Costa, C.; Jorge, P.; Silva, R.; Arêde, A.; Calçada, R.The simulation of the dynamic behavior of the train-track system is strongly dependent on the accuracy of the numerical models of the train and track subsystems. The use of calibrated numerical models of the railway vehicles, based on experimental data, enhances their ability to correctly reproduce the dynamic responses of the train under operational conditions. In this scope, studies involving the experimental calibration of freight wagon models are still scarce. This article aims to fill this gap by presenting an efficient methodology for the calibration of a numerical model of a freight railway wagon based on experimental modal parameters. A dynamic test was performed during the unloading operation of the train, adopting a dedicated approach which does not interfere with its tight operational schedule. From data collected during the dynamic test, five natural frequencies and mode shapes associated with rigid-body and flexural movements of the wagon platform were identified through the Enhanced Frequency-Domain Decomposition (EFDD) method. A detailed 3D finite-element (FE) model of the loaded freight wagon was developed, requiring precise knowledge of the vehicle design details which, in most situations, are difficult to obtain due to confidentiality reasons of the manufacturers. The model calibration was performed through an iterative method based on a genetic algorithm and allowed to obtain optimal values for seven numerical parameters related to the suspension’s stiffnesses and mass distribution. The stability of the parameters considering different initial populations demonstrated the robustness of the optimization algorithm. The average error of the natural frequencies decreased from 8.5% before calibration to 3.2% after calibration, and the average MAC values improved from 0.911 to 0.950, revealing a significant improvement of the initial numerical model.
- Calibration of the numerical model of a freight railway vehicle based on experimental modal parametersPublication . Ribeiro, Diogo; Bragança, C.; Costa, C.; Jorge, P.; Silva, R.; Arêde, A.; Calçada, R.The simulation of the dynamic behavior of the train-track system is strongly dependent on the accuracy of the numerical models of the train and track subsystems. The use of calibrated numerical models of the railway vehicles, based on experimental data, enhances their ability to correctly reproduce the dynamic responses of the train under operational conditions. In this scope, studies involving the experimental calibration of freight wagon models are still scarce. This article aims to fill this gap by presenting an efficient methodology for the calibration of a numerical model of a freight railway wagon based on experimental modal parameters. A dynamic test was performed during the unloading operation of the train, adopting a dedicated approach which does not interfere with its tight operational schedule. From data collected during the dynamic test, five natural frequencies and mode shapes associated with rigid-body and flexural movements of the wagon platform were identified through the Enhanced Frequency-Domain Decomposition (EFDD) method. A detailed 3D finite-element (FE) model of the loaded freight wagon was developed, requiring precise knowledge of the vehicle design details which, in most situations, are difficult to obtain due to confidentiality reasons of the manufacturers. The model calibration was performed through an iterative method based on a genetic algorithm and allowed to obtain optimal values for seven numerical parameters related to the suspension’s stiffnesses and mass distribution. The stability of the parameters considering different initial populations demonstrated the robustness of the optimization algorithm. The average error of the natural frequencies decreased from 8.5% before calibration to 3.2% after calibration, and the average MAC values improved from 0.911 to 0.950, revealing a significant improvement of the initial numerical model.
- Coastal management risk analysis of an embayed beach in Majorca islandPublication . Abreu, Tiago; Parreño-Mas, Benjamín; Pinto-Faria, JoséCoastal erosion affects many coastlines around the world. This is a serious problem for the Balearic Islands, located at the western Mediterranean Sea, since the economy of the region largely relies on tourist activities along the sandy coastline. Therefore, coastal management strategies are required, particularly, in anthropized coasts as it is the case of Cala Millor beach (north-eastern Mallorca). A risk analysis for this micro-tidal sandy beach is performed in this paper. It is recognized that the beach suffers a persistent loss of sediments since its natural balance was changed due to anthropic activities that took place in that Spanish coast in the 1960s. Some solutions can be adopted to solve this problem, but it is important to be aware that, close to the shore, the seabed is covered by a native vegetation known as Posidonia Oceanica. This seagrass meadow plays an important role in this coastal system, being responsible by the lamination of the waves through energy dissipation, which are inextricably linked to coastal morphology. Therefore, any solution needs to address local specificities, and its consequent potential impact must be incorporated into the coastal risk management process. This study analyzes the failure modes identified according to the failure modes and effects analysis/failure mode, effects and criticality analysis, proposing a set of recommendations, in order to mitigate the occurrence of failure modes and to minimize risks.
- Detection of exposed steel rebars based on deep-learning techniques and unmanned aerial vehiclesPublication . Santos, R.; Ribeiro, Diogo; Lopes, Patrícia; Cabral, R.; Calçada, R.In recent years deep-learning techniques have been developed and applied to inspect cracks in RC structures. The accuracy of these techniques leads to believe that they may also be applied to the identification of other pathologies. This article proposes a technique for automated detection of exposed steel rebars. The tools developed rely on convolutional neural networks (CNNs) based on transfer-learning using AlexNet. Experiments were conducted in large-scale structures to assess the efficiency of the method. To circumvent limitations on the proximity access to structures as large as the ones used in the experiments, as well as increase cost efficiency, the image capture was performed using an unmanned aerial system (UAS). The final goal of the proposed methodology is to generate orthomosaic maps of the pathologies or structure 3D models with superimposed pathologies. The results obtained are promising, confirming the high adaptability of CNN based methodologies for structural inspection.
- Efficiency of strengthening techniques assessed for existing masonry buildingsPublication . Diz, Sérgio; Costa, Aníbal; Costa, Alexandre A.The Azores archipelago is a zone with a vast cultural heritage, presenting a building stock mainly constructed in traditional stone masonry. It is known that this type of construction exhibits poor behaviour under seismic excitations; however it is extensively used in seismic prone areas, such as this case. The 9th of July of 1998 earthquake was the last seismic event in the islands, leaving many traditional stone constructions severely damaged or totally destroyed. This scenario led to an effort by the local government of improving the seismic resistance of these constructions, with the application of several reinforcement techniques. This work aims to study some of the most used reinforcement schemes after the 1998 earthquake, and to assess their effectiveness in the mitigation of the construction’s seismic vulnerability. A brief evaluation of the cost versus benefit of these retrofitting techniques is also made, seeking to identify those that are most suitable for each building typology. Thus, it was sought to analyze the case of real structures with different geometrical and physical characteristics, by establishing a comparison between the seismic performance of reinforced and non-reinforced structures. The first section contains the analysis of a total of six reinforcement scenarios for each building chosen. Using the recorded 1998 earthquake accelerograms, a linear time-history analysis was performed for each reinforcement scenario. A comparison was then established between the maximum displacements, inter-storey drift and maximum stress obtained, in order to evaluate the global seismic response of each reinforced structure. In the second part of the work, the examination of the performance obtained in the previous section, in relation to the cost of implementing each reinforcement technique, allowed to draw conclusions concerning the viability of implementing each reinforcement method, based on the book value of the buildings in study.
- Efficient multiscale methodology for local stress analysis of metallic railway bridges based on modal superposition principlesPublication . Horas, Cláudio; Jesus, Abílio M.P. de; Ribeiro, Diogo; Calçada, RuiThis paper presents an advanced submodelling methodology for local stress analysis of complex details of existing metallic railway bridges. The fatigue assessment of connections of large structures based on local methods leads inherently to a multiscale problem that can only be solved by adopting efficient numerical procedures. Aiming to overcome such limitations that influence the analysis process, submodelling techniques and modal superposition principles are combined to fully represent numerically the local geometrical, material and contact properties of the fatigue-critical details. The results of experimental in situ tests are proposed to characterise the numerical models and respective multiscale relation, implementing optimisation and validation procedures. In this work, the suggested efficient multiscale methodology for stress analysis aims to allow the subsequent local fatigue assessment, according to the real mechanism of loading transference, reducing sources of conservatism. All numerical procedures and respective validation thru experimental techniques are illustrated using a real case study.