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- Aplicação dos eurocódigos 0 e 1 – análise comparativa com as congéneres SIA 260 e 261Publication . Ferreira, Débora; Moreno, Carlos; Branco, RicardoOs Eurocódigos 0 e 1 (EN 1990, EN 1991), que substituíram o Regulamento de Segurança e Ações para Estruturas de Edifícios e Pontes (RSAEEP) na quantificação das principais ações a que uma estrutura está sujeita, proporcionaram a uniformização das metodologias de verificação e dimensionamento estrutural a nível da União Europeia. A Suíça é um dos poucos países europeus que continua a seguir normas de dimensionamento internas: as SIA – Société Suisse des Ingénieurs et des Architectes. Para garantir a segurança estrutural há a necessidade de dotar as estruturas de capacidade resistente adequada. Uma das etapas iniciais do processo de dimensionamento consiste na quantificação e combinação das diferentes ações. São abordados, no presente trabalho, as principais ações a considerar no dimensionamento estrutural, bem como os diferentes modelos de combinação das ações.
- Punching shear strengthening of flat slabs: CFRP and shear reinforcementPublication . Moreno, Carlos; Ferreira, Débora; Bennani, Abdelkrim; Sarmento, Ana; Noverraz, MichelPunching in slabs is usually associated to the application of concentrated loads or to the presence of columns. One of the main concerns related to flat slabs is its punching shear capacity at slabcolumn connection, which is subjected to a very complex three-dimensional stress state. Provided that bending capacity is installed, punching shear failure is hence characterized by the development of a truncated cone shaped surface at the slab-column connection. The experimental programme carried out by the authors includes four normal strength concrete slabs (1100×1100×100 mm3), with and without shear reinforcement, submitted to punching under a concentrated load. One of the specimens included typical bent-down bars as shear reinforcement. Frequently, there is the need to strengthen existing flat slabs against punching shear failure. Current paper intends to further investigate the structural response of such reinforcement techniques. One of the strengthening practices, which have been tested within current experimental programme, consists on gluing carbon fibre reinforced polymers on concrete surface. Moreover, the near surface mounted technique has also been tested within current experimental work. Finally, a fourth specimen served as reference. The effects of shear reinforcement and of the carbon fibre reinforced polymers enhancing punching shear capacity are observed.
- Punching shear strengthening of flat slabs: CFRP and shear reinforcementPublication . Moreno, Carlos; Ferreira, Débora; Bennani, Abdelkrim; Sarmento, Ana; Noverraz, MichelPunching in slabs is usually associated to the application of concentrated loads or to the presence of columns. One of the main concerns related to flat slabs is its punching shear capacity at slabcolumn connection, which is subjected to a very complex three-dimensional stress state. Provided that bending capacity is installed, punching shear failure is hence characterized by the development of a truncated cone shaped surface at the slab-column connection. The experimental programme carried out by the authors includes four normal strength concrete slabs (1100×1100×100 mm3), with and without shear reinforcement, submitted to punching under a concentrated load. One of the specimens included typical bent-down bars as shear reinforcement. Frequently, there is the need to strengthen existing flat slabs against punching shear failure. Current paper intends to further investigate the structural response of such reinforcement techniques. One of the strengthening practices, which have been tested within current experimental programme, consists on gluing carbon fibre reinforced polymers on concrete surface. Moreover, the near surface mounted technique has also been tested within current experimental work. Finally, a fourth specimen served as reference. The effects of shear reinforcement and of the carbon fibre reinforced polymers enhancing punching shear capacity are observed.
- Punching shear analysis of slab-column connectionsPublication . Moreno, Carlos; Sarmento, Ana MariaThe paper aims to present an experimental testing program regarding reinforced concrete slabs, with and without shear reinforcement, submitted to punching under both symmetric and eccentric loading. Comparisons between numerical simulations and experimental behaviour results are carried on. The capabilities and limitations of the numerical model to reproduce the brittle punching-shear failure are discussed. The paper opted for a performance assessment of a numerical model, comparing FEM results with known experimental tests properly instrumented. Capability of DIANA software to simulate the punching behaviour of slabs is discussed. The paper demonstrates that the mechanical properties assigned to the element layer containing the bending reinforcement impose the load deflection stiffness behaviour. Good agreement was found between the predicted and the observed deformation behaviour. Nevertheless, the reproduction of the punching ultimate capacity is strongly dependent on the adopted value for the shear retention factor, which appears to be the major decisive parameter. This paper demonstrates that the smeared crack model based on both the concept of strain decomposition (SD) and total strain with fixed orthogonal cracks approach (TSF) can correctly be used for the analysis of the behaviour of slabs submitted to punching shear.
- Strengthening slabs for punching shear using fibre reinforced polymerPublication . Moreno, Carlos; Ferreira, Débora; Sarmento, AnaPunching is generally associated to the application of concentrated loads or to the presence of columns. One of the main concerns related to flat slabs is its punching shear capacity at slab‐column connection, which is subjected to a very complex three‐dimensional stress state. Provided that bending capacity is installed, punching shear failure is characterized by the development of a truncated cone shaped surface at the slab‐column connection. Recurrently, there is the need to strengthen existing flat slabs against punching shear failure. The use of fibre‐reinforced polymer (FRP) is an innovative technology to strengthen concrete structures. In this paper, punching shear strengthening of flat slabs using carbon fibre reinforced polymer (CFRP) is studied. The experimental programme carried out by the authors includes four normal strength concrete slabs (1100×1100×100 mm3), with and without shear reinforcement, submitted to punching under a concentrated load. One of the specimens included typical bent‐down bars as shear reinforcement. Among available strengthening practices, the technique that consists on gluing CFRP on concrete surface have been tested within current experimental programme. Moreover, the near surface mounted (NSM) technique has also been tested within current experiments. Finally, a fourth specimen served as reference. The effects of shear reinforcement and of CFRP enhancing punching shear capacity are observed.
- Application of eurocodes 0 and 1 - comparison with sia 260 and 261 swiss standardsPublication . Branco, Ricardo; Moreno, Carlos; Ferreira, DéboraThe structural safety is one of the most important issues in construction. In order to ensure this safety there is a need to provide the appropriate carrying capacity to the structure. One of the initial stages of the design process is the quantification and combination of the different actions. Eurocodes 0 and 1 (EN 1990, EN 1991) are concerned by defining the basis of structural design and the actions that should normally be considered in the design of buildings and civil engineering works such as imposed load, wind and snow loads, and have brought a consistency of methodologies for structural design across European Union. Switzerland is one of the few countries in Europe which is not included in European Union, and that continues to follow internal standards, the SIA - Swiss Society of Engineers and Architects. Current investigation involved the comparative study of the requirements for safety and serviceability limit states, load combination format, and partial safety factors as well as the main actions to be considered for the structural design and verification. Both codes of practice are analyzed and compared for the different actions. An automatic calculation computer program was also developed during this study in order to estimate the values of the different actions. Finally, a real building was modelled so as to validate the above mentioned program and to analyze the main differences between European and Swiss codes.
- Punching shear analysis of slab-column connectionsPublication . Moreno, Carlos; Sarmento, Ana MariaIn this study, numerical simulations of the experimental behaviour of reinforced concrete slabs tested under punching by the authors are presented. The capabilities and limitations of the numerical model to reproduce the brittle shear failure are discussed.
- Bioclimatic solutions existing in vernacular architecture. Rehabilitation techniquesPublication . Ferreira, Débora; Luso, Eduarda; Fernandes, Sílvia; Vaz, António Jorge Ferreira; Moreno, Carlos; Correia, RafaelThe traditional architecture is founded as a defining element of the identity of a region, and its essence should be preserved and conserved by means of maintenance and recovery actions. Thus, the best solutions and proposals for intervention should be looked for but this doesn’t imply a back to back innovation and at construction progress. This work includes the description of techniques for maintenance and conservation of bioclimatic solutions found and inventoried in the north of the Iberian Peninsula, with special focus on a unique bioclimatic solution known as Sunspace, whose main advantage is to contribute significantly to the improvement of the thermal performance of buildings. It is also important to recover the historical heritage in a sustainable manner, allowing it to become an engine of development for both urban and small rural centres that exist in the periphery of the bigger cities.
- A utilização de equipamento ultrassónico na caracterização mecânica de elementos em betão armadoPublication . Abreu Filho, Marco Antonio; Luso, Eduarda; Moreno, CarlosDevido à grande importância do betão e do betão armado na construção civil, o mercado e a indústria tiveram a necessidade, técnica e econômica, de desenvolver e aprimorar técnicas e ensaios para caracterização do mesmo. Os tipos de ensaios podem ser divididos entre os destrutivos, que inutilizam totalmente ou parcialmente a peça ou o elemento objeto de estudo, e os não destrutivos, que não geram danos, ou geram danos insignificantes que podem ser reparados após os ensaios. Grande parte dos ensaios destrutivos são feitos utilizando provetes recolhidos durante a betonagem, o que inviabiliza a sua utilização no caso de inspeções e diagnóstico em estruturas de betão já existentes. Os ensaios não destrutivos, realizados in-situ, surgem então como importante opção para atestar e certificar a qualidade e especificações dos materiais. Tendo suas primeiras citações na década de 40 do século XX, o ultrassom foi um dos métodos de ensaio não destrutivo que teve muita evolução e ganhou espaço no mercado nos últimos anos. Esse estudo pretende, com o auxílio de um equipamento ultrassónico atual tipo scanner, nortear a precisão e as capacidades desse método de realizar a caracterização mecânica de elementos em betão e betão armado. De entre as caracterizações pretende-se estimar a resistência à compressão e à tração, localizar armaduras, medir peças e determinar a profundidade de fendas e fissuras em elementos de betão e betão armado.