Percorrer por autor "Fernandes, Paulo"
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- Admixture tuning for high‐performance concrete for the production of novel precast pre‐stressed long‐span girders for highway overpassesPublication . Fernandes, Paulo; Pala, Helena; Cavaco, Eduardo; Tiago, Paulo; Júlio, EduardoThe improvements observed in concrete technology in the last decades, namely the production of Portland cement CEM I 52.5 R, the development of third generation super-plasticizers, and the commercialization of additions with high pozzolanic properties, turned possible the development of new concrete products using high performance concrete (HPC). Nevertheless, their implementation in the production process of the conservative precast concrete industry is not yet a reality. In this paper, the development and characterization of a HPC exhibiting high workability in the fresh state and high compressive strength in hardened state is presented. This HPC aims at producing, on a competitive basis, precast pre-stressed long-span girders for highway overpasses. For this reason, the main goal was to maximize the abovementioned properties but using the constituents available at the concrete precast company supporting the research. A set of different commercial admixtures was gathered and their influence on both compressive strength and workability of concrete was experimentally investigated. Results show that the compatibility between the admixture and the cementitious material is of paramount importance. By selecting the best type of the considered super-plasticizers and by optimizing its dosage, it was possible to increase the workability from class S1 to S5 and, simultaneously, increase the compressive strength in circa 50%, up to 120 MPa, at 28 days of age.
- Analysis of the influence of cladding panels in the seismic behaviour of a prc industrial buildingPublication . Ostetto, Liana; Sousa, Romain; Rodrigues, Hugo; Fernandes, PauloRecent reports on the latest earthquakes in Italy and Turkey have highlighted some critical problems in the connections of cladding panels on industrial precast reinforced concrete (PRC) structures. The panel connections did not perform as expected, causing non-structural damages and, in most cases, leading to the panels overturning. The damage and collapse of these elements may result in significant losses of human lives and large socio-economic impacts due to business interruption. Despite being demonstrated that cladding panels can have a significant contribution on seismic response, these elements are often considered as non-structural, ignoring the interaction with the RC frame, and considering that they do not influence the seismic behaviour. Making use of a simplified macro element, this study assesses the seismic capacity of commonly employed claddings-to-structure connections, as well as the interaction of the cladding panels with the PRC industrial buildings. The analyses were carried out considering a PRC building representative of the Portuguese industrial park, studied with and without cladding panels. The seismic behaviour of the structure are assess considering both non-linear static and dynamic procedures.
- Assessment of existing rc precast industrial buildings according with eurocode 8 - part 3Publication . Batalha, Nádia; Rodrigues, Hugo; Sousa, Romain; Varum, Humberto; Fernandes, PauloPrecast reinforced concrete (PRC) buildings are common in the Portuguese industrial park, as well as throughout Europe. In past earthquakes, namely in Italy and Turkey, this typology of buildings showed a poor performance, namely at structural level. One of the major concerns at structural level regards the connection between the beams and columns. In recent surveys at the Portuguese industrial buildings, it was observed that the buildings built before 1980 present, most of the times, only friction connections between beam and columns. This type of connection is pointed as one of the weakest structural system in this typology of structures and consequently led to serious local and global damage when subjected to seismic loads. Regarding this issue, it was considered appropriate and necessary the study of existing Portuguese buildings with this type of beam-to-column connection and compare it with the use of mechanical connections (dowels), which is a more common solution in the recent buildings. The seismic behaviour of two PRC buildings built with these two solutions was analysed considering nonlinear static and dynamic analyses addressing both global and local (connections) response parameters. When analysed in view of the seismic regulation for existing buildings (Eurocode 8 –Part 3), the results obtained show that, overall, this typology of buildings present an acceptable structural performance. Nonetheless, unsatisfactory performance was observed at the beam-to-column connection in one of the buildings built without steel dowels. The results presented in this study highlight the need to consider adequate models to simulate these connections in order to accurately represent the seismic behaviour on the structure and identify possible limitations in the use of nonlinear static procedures to assess the seismic performance of this typology of buildings. In general, the buildings in study, located in a region of moderate seismicity, exhibited a satisfactory behaviour. However particular attention should be paid to beam-to-column connections, especially in the case of friction connections. In this regard it is important to accurately represent in the model the mechanisms involved in the connections, particularly in buildings located in moderate to high seismic zones.
- Estudo para a requalificação/modernização da ETAR das OlhalvasPublication . Pala, Helena; Vieira, Judite; Oliveira, Mário; Costa, António; Antunes, Raquel; Fernandes, PauloO presente trabalho refere-se a um estudo realizado por uma equipa multidisciplinar do Politécnico de Leiria com o macro objetivo de investigar, identificar e definir as melhores soluções de requalificação/modernização da ETAR das Olhalvas, mitigando o impacto que esta infraestrutura ainda tem no contexto em que se insere e as possibilidades de reutilização de parte do efluente desta unidade numa perspetiva de uso racional da água, evitando assim o uso de água tratada para fins que não o exigem. Partindo de uma análise do funcionamento da ETAR suportada em dados relativos aos anos 2016 a 2020, compreendendo a caracterização dos caudais e cargas afluentes à estação e sua comparação com os valores de projeto, o estudo analisou a eficiência do tratamento e os principais parâmetros indicadores da qualidade, nomeadamente CQO, CBO5, SST, NTotal e PTotal. Esta análise evidenciou o bom funcionamento e adequação para os caudais e características do afluente da ETAR e eficiência muito elevada, traduzindo-se em reduções muito significativas da carga poluente presente no afluente. A ausência de informações objetivas sobre o impacto da descarga do efluente no meio recetor e de caracterização do próprio meio, justificou uma campanha de monitorização das águas superficiais da bacia hidrográfica do rio Lis, entre outubro de 2020 e abril de 2021, monitorizando o Rio Lis a montante e jusante da ETAR e um afluente ao Rio Lis, a Ribeira do Sirol, na sua confluência com este. Esta campanha revelou-se muito importante na quantificação do impacto do efluente sobre o meio recetor, observando-se uma ligeira alteração no padrão de qualidade em alguns meses para os parâmetros NTotal, nitratos (N-NO3) e fosfatos (P-PO4), mas destacando-se que nos restantes parâmetros, a saber, pH, CQO, CBO5, SST, N-NH4 e substâncias tensioativas, não foram detetadas variações. Estas observações suportaram um conjunto de recomendações de medidas de requalificação/modernização, propondo a melhoria dos tratamentos existentes ou a introdução de novos tratamentos. A importância que a comunicação do papel destes equipamentos tem junto daqueles que são os principais beneficiários do seu bom funcionamento, populações servidas e comunidades que habitam o território onde se implantam, nortearam o estudo sobre os planos e estratégia de comunicação deste equipamento. Partindo das boas práticas identificadas em territórios e situações congéneres e valorizando as campanhas emblemáticas do passado deixam-se um conjunto de propostas de estratégia e planos de comunicação que permita aproximar a ETAR de Olhalvas das populações e territórios que servem, visando a sua integração num objetivo maior que é a melhoria contínua da qualidade do Rio Lis.
- Experimental characterization of the out-of-plane behaviour of masonry infill walls made of lightweight concrete blocksPublication . Agante, Marta; Furtado, André; Rodrigues, Hugo; Arêde, António; Fernandes, Paulo; Varum, HumbertoMasonry infill walls are widely spread over the reinforced concrete buildings due to different demands. The buildings' thermal energy efficiency is a top priority nowadays since many of the existing building stock comprises buildings with low energy performance. The buildings' external envelope is undergoing a transformation with the vertical hollow concrete blocks' appearance with high thermal and acoustic demands. However, recent evidence from a strong earthquake shows that the masonry infill walls are quite vulnerable to out-of-plane loadings and were responsible for many casualties, injuries and economic losses. Based on that, this work's main objective is to study the out-of-plane (OOP) behaviour of masonry infills made with vertical hollow concrete blocks. The experimental campaign comprises the OOP testing of three full-scale infill walls made up of these masonry units, one of them as-built without previous damage, one with previous damage due to an earlier in-plane test and the third one retrofitted. All the tests consisted of applying the loading–unloading-reloading history of imposed displacements in the OOP direction through a uniformly distributed load. The results will be presented in terms of OOP force–displacement responses, damage evolution and energy dissipation capacity. The test results are compared to assess the previous damage effect and the retrofit technique's effectiveness. A final study is presented concerning the masonry unit and slenderness effect with other literature results.
- Flexural behavior of slender long‐span precast prestressed high‐strength concrete girdersPublication . Fernandes, Paulo; Cavaco, Eduardo; Maranha, Paulo; Júlio, EduardoThe flexural behavior of slender (1/40) long-span precast high-strength concrete girders was experimentally investigated as a competing solution to steel alternatives for highway overpasses. Half-scale specimens were produced using an economical and high-strength (120 MPa) concrete mixture, non-fiber reinforced, designed only with conventional raw materials, currently available at Portuguese precast companies. Two girder specimens were subjected to quasi-static short-term loading up to structural failure in bending. Results have shown the typical behavior of conventional reinforced concrete members in bending, despite the brittle behavior of non-fiber-reinforced high strength concretes. Results also showed acceptable ductility (2.6) and the ability of the girder specimens to experience large deformation without significant softening. An analytical approach, based on plane sections and short-term stress–strain constitutive model recommended by the Eurocode 2 for concrete up to the C90/105 strength class, showed to predict accurately the behavior of girders in bending, both to ultimate and serviceability limit states, including cracking, yielding, maximum loads, and ultimate deflections.
- Influence of Beam-to-Column Connections in the Seismic Performance of Precast Concrete Industrial Facilities, Structural Engineering InternationalPublication . Rodrigues, Rodrigo; Vitorino, Hugo; Batalha, Nádia; Sousa, Romain; Fernandes, Paulo; Varum, HumbertoPast earthquakes have brought attention to the poor performance of precast reinforced concrete structures, especially relating to beam-to-column connections. The evaluation of different methodologies for the analysis of beam-to-column connections in industrial buildings is important. In the present work numerical analyses developed allowed the study of the effect that different story heights and connection properties have on frequencies, drifts, seismic coefficients and connection sliding. The results showed that the friction between concrete elements and the consideration of neoprene have a small impact on the drift demands in the columns and the seismic coefficients of the structures analyzed; on the other hand, the effect of steel dowel on the drift demands and seismic coefficients is significant. The comparison of models with different properties and connections allowed a better understanding of the parameters that affect the seismic behavior of precast reinforced concrete buildings the most and provide indications for building more accurate and efficient numerical models.
- PrefacePublication . Bartolo, Paulo; Fernandes, PauloThis issue contains the papers presented at ICTE2013, the Third ECCOMAS Thematic Conference on Tissue Engineering, held in Leiria, Portugal from 6 to 8 June 2013, sponsored by ECCOMAS, the European Community Association on Computational Methods in Applied Sciences.
- Seismic precast. Seismic performance assessment of existing precast industrial buildingsPublication . Furtado, André; Arêde, António; Rodrigues, Fernanda; Rodrigues, Hugo; Vitorino, Hugo; Varum, Humberto; Ostetto, Liana; Batalha, Nádia; Fernandes, Paulo; Sousa, Romain; Silva, VítorPast seismic events exposed important fragilities in precast reinforced concrete buildings and highlight the need to undertake measures to mitigate future losses.The study presented identify potential structural and nonstructural fragilities of the Portuguese building stock and provide guidance to reduce the associated direct and indirect socio-economic impact
- Sustainability and Automation in Smart ConstructionsPublication . Rodrigues, Hugo; Gaspar, Florindo; Fernandes, Paulo; Mateus, ArturThis book gathers outstanding papers presented at the Conference on Automation Innovation in Construction (CIAC-2019). In recent years, there have been significant transformations in the construction sector regarding production and the use of computers and automation to create smart and autonomous systems. At the same time, innovative construction materials and alternative technologies are crucial to overcoming the challenges currently facing the building materials industry. The book presents numerous examples of smart construction technologies, discusses the applications of new construction materials and technologies, and includes studies on recent trends in automation as applied to the construction sector.