Artigos de Revista
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Blue gum: assessment of its potential for glued laminated timber beams
Portuguese forests are mainly composed of hardwoods, which represent 69% of the forest area in 2010, being Blue gum (Eucalyptus globulus Labill.) the most abundant species (26%). The suitability of Blue gum for structural applications was demonstrated in previous studies. However, the most common uses are still related to the pulp and paper industry as well as energy production, mainly due to sawing and drying issues. The present paper describes a preliminary study on the potential application of non-destructive tests and analytical methods to predict the most important mechanical properties of glued laminated timber (glulam) beams made of Blue gum. The potential of mixed beams made of Blue gum and poplar was also analysed. The longitudinal vibration method and the transformed section method were considered. A total of 11 non-finger jointed full-scale glulam beams (7 of Blue gum and 4 mixed) were manufactured in the laboratory and tested for modulus of elasticity and bending strength assessment. After the bending tests, the density and moisture content of the beams were determined, and the bonding performance was checked by delamination and shear strength tests. Correlation coefficients were established between the predicted values and the experimentally assessed mechanical properties, indicating a huge potential of the predictive methods used. The mechanical properties of non-finger jointed beams tested were above the typical values found in the literature for the most common hardwoods available in European forest.
Ano: 2020
Número Páginas:
9p.
Autor(es): Martins, C.; Dias, A.; Cruz, H.
Revista: European Journal of Wood and Wood Products
Editor: Springer-Verlag GmbH
Volume:
Volume 78, nº 4.
Keywords: Beams; Glued laminated timber; Production; Blue gum
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Bond behaviour between steel / stainless-steel reinforcing bars and low binder concrete (LBC)
Reducing the cement content of concrete is of paramount importance towards sustainability, since its production process is highly energy-consuming and delivers massive CO2 emissions to the atmosphere. In this paper, the bond behaviour between steel and stainless-steel reinforcing bars and Low Binder Concrete (LBC), produced with approximately one half and almost one fourth of the minimum cement content prescribed in the standards, is experimentally investigated. Results show the compactness of the mixture to be the main parameter controlling bond development, more than the mixture compressive strength as suggested in published results and standards. A more compact and denser mixture increases the contact surface between the reinforcing bars and concrete, improving friction between both. LBC mixtures with lowered cement content, up to almost one fourth of the minimum recommended, can be used without jeopardizing the bond strength of reinforcing bars. LBC mixturespromise to be a fitting approach towards greater sustainability in the concrete production sector.
Ano: 2020
Número Páginas:
11p.
Autor(es): Freitas, E.; Louro, A. S.; Costa, H.; Júlio, E.; Pipa, M.; Cavaco, E.
Revista: Engineering Structures
Editor: Elsevier Ltd.
Volume:
Volume 221, nº 111072.
Keywords: Sustainability; Low binder concrete; Steel / stainless steel rebars; Bond behaviour
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Bond behaviour between steel/stainless-steel reinforcing bars and low binder concrete (LBC)
Reducing the cement content of concrete is of paramount importance towards sustainability, since its production process is highly energy-consuming and delivers massive CO2 emissions to the atmosphere. In this paper, the bond behaviour between steel and stainless-steel reinforcing bars and Low Binder Concrete (LBC), produced with approximately one half and almost one fourth of the minimum cement content prescribed in the standards, is experimentally investigated. Results show the compactness of the mixture to be the main parameter controlling bond development, more than the mixture compressive strength as suggested in published results and standards. A more compact and denser mixture increases the contact surface between the reinforcing bars and concrete, improving friction between both. LBC mixtures with lowered cement content, up to almost one fourth of the minimum recommended, can be used without jeopardizing the bond strength of reinforcing bars. LBC mixtures promise to be a fitting approach towards greater sustainability in the concrete production sector.
Ano: 2020
Número Páginas:
11.
Autor(es): Freitas, E.; Louro, A. S.; Costa, H.; Cavaco, E.; Júlio, E.; Pipa, M.
Revista: Engineering Structures
Editor: Elsevier, Ltd.
Volume:
221.
Keywords: Sustainability; Low binder concrete; Steel / stainless steel rebars; Bond behaviour
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Characterization of the Mechanical Performance in Compression Perpendicular to the Grain of Insect-Deteriorated Timber
Among biological agents, insect attacks may cause severe degradation of timber structuresin the service life of buildings which leads to lower mechanical performance and, thus, maintenanceproblems over time. Additionally, compression perpendicular to the grain always features a weak spotwith respect to the long-term mechanical performance of timber members and joints. In the presentwork, the respective strength and elastic modulus were thus investigated for insect deterioratedwood. Following a standardized geometry, small samples degraded by anobiids were extractedfrom beams made of sweet chestnut wood (Castanea sativa Mill.) that were removed from service.Visual assessment of the external wood surfaces was then performed to identify areas infested byinsects. Afterwards, destructive monotonic compression tests were carried out perpendicularly tothe grain on the damaged area to determine the loss of compressive strength and elastic modulus.The experimental results showed that the loss of compressive strength and elastic modulus mightbe linearly correlated to the wood density loss for small samples infested by insects. Nonetheless,future work should focus on determining accurately the density loss in the insect-deteriorated partthrough non- or semi-destructive tests, in order to establish stronger relationships with the mechanicalproperties loss investigated.
Ano: 2020
Autor(es): Verbist, M.; Branco , J.; Lina Nunes
Revista: Buildings
Editor: MDPI
Volume:
10, 14.
Keywords: destructive tests; compression; insect wood deterioration; timber
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Low-density cardoon (Cynara cardunculus L.) particleboards bound with potato starch-based adhesive
In the present work, and for the first time, totally biosourced low-density particleboardswere produced using cardoon particles (a no added value by-product from the Portuguese cheese making industry), bound with a potato starch adhesive. Different starch/cardoon ratios (0.6, 0.8, 1 and 1.2) were tested and the effect of different bio-based additives (chitosan, wood fiber and glycerol) on the performance of the adhesive system was evaluated. The best result was obtained for a formulationwith a starch/cardoon mass ratio of 0.8, a chitosan/starch mass ratio of 0.05 and a water/starch mass ratio of 1.75. The particleboards produced had a density of 323 kg-m-3, internal bond strength of 0.35 N.mm-2 and thickness swelling of 15.2%. The values of density and internal bond strength meet the standard requirements of general-purpose lightweight boards for use in dry conditions according to CEN/TS 16368 specification. Moreover, the susceptibility of the formulations with best results was established against subterranean termites and one decay fungi.
Ano: 2020
Número Páginas:
16.
Autor(es): Monteiro, S.; Lina Nunes; Martins, J.; Magalhães, F.; Carvalho, L.
Revista: polymers
Editor: MDPI Initiatives
Volume:
12, nº 8.
Keywords: Physico-mechanical properties; Cardoon; Starch-based adhesive; Low-density particleboards
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Macrobiological degradation of esterified wood with sorbitol and citric acid
There is a need for new solutions in wood protection against marine wood borers andtermites in Europe. A new solution could be the esterification of wood with sorbitol and citric acid(SCA) since these are inexpensive and readily available feedstock chemicals and have shownprotective properties against fungal wood degradation in earlier studies and preventedmacrobiological degradation, as shown in this study. Protection of wood products in the marineenvironment lacks available wood preservatives that are approved for marine applications. Termiteinfestation is opposed mainly by biocide treatments of wood. Several wood modification systemsshow high resistance against both marine borers and subterranean termites. However, the existingcommercialized wood modification products are costly. Both macrobiological forms of degradationrepresent a great threat for most European wood species, which are rapidly and severely degradedif not properly treated. This study investigated esterified wood in standard field trials againstmarine wood borers, and against subterranean termites in laboratory trials in a no-choice and choicetest. The treatment showed good resistance against wood borers in the marine environment afterone season and against subterranean termites in the laboratory after eight weeks. The low termitesurvival rate (SR) in the no-choice test during the first week of testing indicates a mode of actionthat is incomparable to other wood modification treatments.
Ano: 2020
Número Páginas:
11p.
Autor(es): Treu, A.; Lina Nunes; Larnoy, E.
Revista: Forests
Editor: MPDI
Volume:
11, 776.
Keywords: Subterranean termites; Marine wood borers; Polyesterification; Wood protection
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Mechanical performance of glulam products made with Portuguese poplar
Due to its average mechanical properties, poplar, a fast-growing species, has been disfavored compared to stronger species for several decades. Wood-based products may help changing that perspective and thus, poplar has been gaining its marketshare for structural uses. A state-of-the-art review concerning the use of poplar to produce glued laminated products, with special focus on the use of Portuguese poplar, is presented. The Portuguese forest produces a great variety of species. Themost common poplar species found in this country are Populus x canadensis, P. nigra L., and P. alba L. Despite its limited availability, and the market hesitation on its structural application, recent studies on poplar grown in the Portuguese forestshowed its suitability for structural purposes. Glued laminated timber (GLT) beams made with this species revealed a very promising mechanical behavior. Bending strength tests evidenced a ductile behavior on more than 70% of the beams, whichmotivated deepening the study on the raw material used to produce those beams. To predict the mechanical behavior of such beams, a 3D numerical model was developed. The numerically predicted results were compared with the experimental ones,showing very good agreement between both approaches.
Ano: 2020
Número Páginas:
9p.
Autor(es): Monteiro, S.; Martins, C.; Dias, A.; Cruz, H.
Revista: European Journal of Wood and Wood Products
Editor: Springer-Verlag GmbH
Volume:
Published online: 16 de julho de 2020.
Keywords: Portuguese poplar; Glulam products; Mechanical performance
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Proposta de lei de aderência entre varões de aço e betões com baixa dosagem de ligante com agregados naturais/reciclados
O betão com baixa dosagem de ligante (LBC - low binder concrete na denominação anglo-saxónica) e o betão com baixa dosagem de cimento com agregados reciclados (LCRAC - low cement recycled aggregate concrete ) são alterativas eco-eficientes ao betão de cimento Portland com agregados naturais por apresentarem um menor impacto ambiental. Para contribuir para o estudo da viabilidade de aplicação estrutural do LBC e do LCRAC, apresentam-se neste artigo os resultados obtidos numa campanha experimental de ensaios de arrancamento (pull-out tests), realçando o desempenho obtido ao nível da relação entre a tensão de aderência e o deslizamento do varão de aço. Os resultados experimentais foram comparados com as propostas de previsão existentes e apresenta-se uma primeira proposta de lei para descrever a relação tensão de aderência-deslizamento, considerando a compacidade, os agregados reciclados, o diâmetro do varão e a respetiva área relativa das nervuras transversais. A influência positiva da compacidade na aderência foi validada através da comparação dos resultados obtidos com os resultados decorrentes da proposta existente no Model Code 2010.
Ano: 2020
Número Páginas:
14p.
Autor(es): Pereira, T.; Louro, A. S.; Costa, H.; Júlio, E.
Revista: Revista Portuguesa de Engenharia de Estruturas
Editor: LNEC | Divisão de Divulgação Científica e Técnica
Volume:
Série III, n.º 14.
Keywords: Relação tensão de aderência-deslizamento; Aderência varão-betão; Elevada compacidade; LCRAC; LBC; Sustentabilidade
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A semi-destructive assessment method to estimate the residual strength of maritime pine structural elements degraded by anobiids
In this article, an assessment method toestimate the residual strength of pine structural ele-ments degraded by anobiids is presented. This novelmethod was developed in the laboratory to be usedin situ and is based on the strength required to withdrawa screw on the surface of degraded timber. Samples ofdegraded maritime pine (Pinus pinaster Ait.) weresubmitted to micro-computed tomography (l-XCT) toquantify density loss. This parameter is highly corre-lated with mechanical properties thus central for theassessment of timber structural capacity. Density lossvalues have been correlated with both screw withdrawalforce and shear parallel to the grain strength showingsignificant relationships between these parameters.Using these correlations, the density loss of a degradedelement and its shear strength parallel to the grain viathe screw withdrawal force can be estimated enabling avalid quantitative assessment of the timber elementsresidual strength and, therefore, contributing to reduceunnecessary replacement, to boost eco-efficient inter-ventions and to provide foundations required to performexperimental modelling tests.
Ano: 2019
Autor(es): Parracha, J.; Pereira, M.; Maurício, A.; Saporiti Machado, J.; Lina Nunes
Revista: Materials and Structures
Editor: Springer
Volume:
52:54.
Keywords: Damage assessment; Screw withdrawal; Micro- computed tomography; Anobiid infestation; Timber
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Avaliação e mitigação dos riscos em património construído: risco sísmico, de galgamento costeiro e de incêndios florestais
O risco refere-se à probabilidade de ocorrerem danos causados pela manifestação de um determinado perigo, sendo função da perigosidade, da exposição (de pessoas e bens) e da vulnerabilidade dos elementos expostos face a esse perigo.Um componente essencial da avaliação do risco è a análise da perigosidade associada aos perigos identificados num dado território, sejam de origem natural ou decorrentes da ação humana. Outro componente essencial é a análise dos elementos (pessoas e bens) expostos aos perigos, bem como as características que contribuem para a suavulnerabilidade - ou a sua resiliência em situação de acidente grave ou de catástrofe. Nesta comunicação dá-se conta de alguns estudos desenvolvidos pelo LNEC nos domínios da avaliação da perigosidade e da vulnerabilidade sísmica das construções, da perigosidade de agitação costeira e risco de galgamentos costeiros e da avaliação da vulnerabilidade de edifícios aos incêndios florestais.
Ano: 2019
Número Páginas:
9p.
Autor(es): Cruz, H.; Fortes, C. J. E. M.; Craveiro, J.; Carvalho, A. M.
Revista: Revista Património
Editor: Direção Geral do Património Cultural, Imprensa Nacional-Casa da Moeda, S.A.
Volume:
6.
Keywords: Erosão costeira; Incêndios florestais; Galgamento oceânico; Risco
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Comunicações
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Testing of non-destructive methods and wood natural and conferred durability for drywood termites detection and control
The invasive drywood termite Cryptotermes brevis (WalkerJ was accidentally introduced In the Azores Islands (Portu¬galJ, causing severe damage to structural timbers in buildings. Research on efficient monitoring and control methods is crucial to the definition of future integrated pest management strategies and for the preservation of wooden struc¬tures in the Azorean Islands.Blocks of eight wood species [white tola, kambala, sucupira, Norway spruce, redwood, Australian blackwood, blue gum and Japanese cedar) and two wood derived products [oriented strand board - OSB and medium-density fiberboard¬ MDF were exposed for two years, to drywood termites, inside a house with an active Infestation. One organic solvent [propiconazole, 1.22% , permethrln, 0.24%) was applied to all wood species and 0SB: MDF was not submitted to any treatment. Two different methods for organic solvent application were used: by brushing or by immersion. Drywood termites attack was evaluated through the observation of: sealed or no sealed holes In wood or wooden products, pel¬lets or termites presenceA redundancy analysis was performed and three variables were considered significant, no treatment, OSB and MDF. Generally, non treated blocks of all wood species and 0SB were the most consumed. 0SB was severely attacked, since it had the higher number of holes, although some were not sealed, indicating possible difficulties in drywood termites installation. Some variables showed 100% protection against drywood termite attack during the test period:a) organic solvent application [sucupira and white tola), b) organic solvent applied by immersion [Australian blackwood, Norway spruce, japanese cedar and kambala); c) organic solvent applied b~ brushing (redwood and blue gum). Untreated kam¬bala and blue gum had the lowest number of holes in the bloc"s though severe infestation of blue gum sapwood had been found previously on the same buildingNon destructive techniques for termites' detection are very Important for early prevention and control measures. A microwave detection device and an acoustic detection device were tested for termites' detection. Microwave detector negative detections were false in half of detections made: positive detections were false in 42% of the cases. For the acoustic detector 15% of negative detections were correct; all positive detections were correct. Acoustic and microwave detection techniques potential In detecting early Infestation of C. brevis should be further investigated.
Ano: 2012
Número Páginas:
1.
Autor(es): Duarte, S.; Amaral, C.; Lina Nunes
Keywords: Acoustic detection; Microwave detection; Wood treatment; Natural wood resistance; Cryptotermes brevis
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The effects of wood industry in the economical development of Kosovo
Kosovo is a relatively small country with 10870 km2 where 42% of its territory is covered with trees. To date, Kosovo has passed through three important phases of economic development: the emergency phase after the recent war, the second phase with. the privatization of social enterprises and the present third phase of sustainable developmentThe after war period was very important for the forest sector as it led to its reconstruction, privatization and development aiming at the internal and foreign markets. Positive developments in the field of wood industry led to a marked increase in the number of work places offered and consequent requirement for a specialized and qualified workforce.These developments have been sustained by higher education programs addressing these issues. One of the study programs is offered by the Faculty of Applied Technical Sciences, in Ferizaj, within the University of Prishtina. This is the only higher education institution in Kosovo, which for 35 years has been offering opportunity to study in wood industry and cooperates with wood processing enterprises and with the Kosovo Wood Processing Association.Curriculum projects are focused in a way that the study process should be more closely related with industrial practices and scientific analyses of all practical parts in the economical context. The large proportion of forests in Kosovo represents a relatively good potential for development of this sector both for the domestic market, and for exports of wood products. This sector can also be very attractive for foreign investments and can generated new jobs.It is therefore essential to have scientific and technical knowledge on the national forests as well as on the species' quality for wood processing.
Ano: 2012
Número Páginas:
2.
Autor(es): Bajraktari, A.; Bouriaud, L.; Petutschnigg, A.; Lina Nunes; Pereira, H.
Keywords: Curriculum; Qualification; Development; Wood industry; Forest
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Wood treatment by paraffin impregnation - preliminary research
Pinus pinaster wood was impregnated with paraffin to different levels using a hot-coldprocess with the hot step at 170-180 ºC and 2-4h. Weight gain, density, equilibriummoisture and dimensional stability (ASE) at 35% and 65% relative humidity and termitedurability against Reticulitermes grassei (Clément) were determined. The weight gain(WG) ranged between 16% and 87% according to treatment. It was determined that 30minutes in the cold bath was enough to reach maximum penetration. Density increasedfrom 0.57 to 0.99, almost reaching the water density. ASE ranged between 38-96% and16-71% for respectively 35% and 65% relative humidity. The best anti shrinkingefficiency (ASE) was obtained for a combined treatment at 180 ºC (4h) and 61% WG.Nevertheless the use of a higher temperature bath did not significantly improve thedimensional stability when compared at the same paraffin WG. Equilibrium moisturecontent decreased drastically due to the treatment from 9.9%, 12.0% to 0.5% and 2.1%for 35% and 65% relative humidity. Termite durability improved from level 4 to level 3of attack. Treated wood presented higher termite mortality (52%) against (17%) ofuntreated wood. The preliminary tests with paraffin impregnation showed that wood haslower equilibrium moisture, higher dimensional stability and density and a higher resistance against termites.
Ano: 2012
Número Páginas:
329-332pp.
Autor(es): Esteves, B.; Lina Nunes; Domingos, I.; Pereira, H.
Keywords: Pinus pinaster; Paraffin treatment; Equilibrium moisture; Durability; Dimensional stability
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A madeira na edificação de paredes
A madeira sempre existiu em abundância no território nacional. Como material único ouconjugada com outros, a madeira assumiu um papel importante na construção de cidades como Lisboa, Guimarães, Porto ou Lamego. De facto, a imagem urbana de muitas áreas resulta, principalmente, da utilização de madeira na construção de segundos ou terceiros pisos e da possibilidade de edificar trapeiras e mansardas sobre as coberturas. Também, em zonas piscatórias, a madeira foi o material escolhido para a edificação sobre estacaria ou, maisrecentemente, sobre fundações de betão.O presente artigo, inserido no âmbito de uma dissertação de doutoramento na Universidade de Évora e em colaboração com o Laboratório Nacional de Engenharia Civil, pretende dar a conhecer a riqueza e diversidade dos sistemas construtivos de paredes interiores e exteriores em que a madeira é o principal material. Na maioria das vezes, o seu esqueleto é cheio com alvenarias detijolo ou pedra e argamassas de terra ou areia e cal. Exteriormente, é protegido com rebocos, lousas em escama ou chapas onduladas pintadas. Wood has always existed abundantly in the Portuguese territory. Either used as a single material or in combination with others, it has taken a major role in urban constructive sceneries such as Lisboa, Guimarães, Porto or Lamego. In fact, it has been a key factor in the overall image of such urban areas as it was frequently used in second and third floors build ups as well as in dormers and top roof lofts. Also, in fishing areas, wood can be widely found on buildings on piles or, morerecently, on concrete foundations. This research, included as part of a doctoral dissertation at the University of Évora with the collaboration of National Laboratory for Civil Engineering, aims to reveal the richness and diversity of partition and external wall constructive systems where wood is the main material. In most cases,the skeleton is filled in with brick, masonry, earth, sand and lime mortars, and on the outside it is finished with plaster, flake slates or painted corrugated iron sheet. The article proposes to explorethe different building systems.
Ano: 2011
Número Páginas:
8.
Autor(es): Fonseca, I.; Saporiti Machado, J.
Editor: Departamento de Engenharia Civil da FCTUC
Keywords: Wattle and daub; Timber structures; Walls; Tabique; Estruturas de madeira; Paredes
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Aging effect on the integrity of traditional portuguese timber roof structures
Traditional buildings basically include natural and autochthonous construction materials and are built with sustainable construction techniques. The knowledge of these materials
Ano: 2011
Número Páginas:
8.
Autor(es): Murta, A.; Varum, H.; Pinto, J.; Ramos, L.; Cunha, V.; Cardoso, R.; Lina Nunes
Editor: Greca - Artes Gráficas
Keywords: Roof structures; Sustainability; Rehabilitation; Used timber; Aging effect
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An experimental approach to the treatment and consolidation of degraded timber elements from a XIX century building
This paper presents the in situ experimental conservation work performed on three timberstructural elements from a XIX century building: two floor beams and one roof beam.This palace was built in 1877 in the centre of Lisbon initially with residential purposes. It has four floors, with timber structural horizontal elements, stairs and roof beams(generally of Pinus sylvestris). The exterior walls are made of irregular stone masonry bedded on mortar, rendered and painted.
Ano: 2011
Número Páginas:
9.
Autor(es): Henriques, M. D.; Lina Nunes; Brito, J.
Keywords: Consolidation; Degradation; Buildings; Wood
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Assessment of the structural properties of timber members in situ - a probabilistic approach
The assessment of the structural performance of existing timber structures is dependent,among other factors, on the capacity to evaluate the physical and mechanical properties of structural timber elements in situ. This paper discusses the possibilities/advantages of using a probabilistic approach to obtain a more reliable prediction of the referenceproperties of these timber members in situ. The presented approach combines informationfrom common non-destructive techniques (NDT), such as visual assessment andultrasounds, and those from semi-destructive tests (SDT), as meso tension specimens andwood cores. An application of this approach to maritime pine (Pinus pinaster Ait.) andchestnut (Castanea sativa Mill.) timber pieces of structural dimension is presented.
Ano: 2011
Número Páginas:
12.
Autor(es): Saporiti Machado, J.; Lourenço, P.; Palma, P.
Keywords: Visual assessment; Structures; Non-destructive techniques; Modulus of elasticity; Bending strength
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Avaliação do ajustamento de distribuições de probabilidade ao comportamento à flexão de Pinho bravo
Este trabalho visa analisar o efeito nos valores característicos de resistência mecânica do Pinho bravo nacional (Pinus pinaster Ait.), resultante do ajustamento de diferentes distribuições de probabilidade. No estudo foram utilizados resultados de ensaios conduzidos em 1990 no âmbito de um projecto europeu. As propriedades analisadas foram a resistência e o módulo de elasticidade à flexão e a massa volúmica. O estudo considerou as classes de qualidade englobadas na norma portuguesa NP 4305 - Classificação Visual de Madeira de Pinho Bravo para Estruturas (IPQ 1995). No que se refere às distribuições de probabilidade foram estudadas as distribuições estatísticas normais, lognormal e Weibull bi-paramétrica. Data from mechanical tests of Portuguese maritime pine timber, which was gathered in 1990 was analysed for mechanical properties such as bending strength, modulus of elasticity and density. Visual grades were determined using the Portuguese visual grading standard NP4305 (IPQ 1995) and were analysed for their strength profiles. Normal, lognormal and Weibull distributions were determined and compared to the dataset.
Ano: 2011
Número Páginas:
6.
Autor(es): Simões, L.; Saporiti Machado, J.; Cruz, H.; Negrão, J.
Editor: Departamento de Engenharia Civil da FCTUC
Keywords: Statistical distributions; Mechanical properties; Tests; Distribuições estatísticas; Caracteristicas mecânicas; Ensaios
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Avaliação do efeito dos nós no comportamento à compressão axial de madeira por meio de termografia.
Os nós constituem um dos defeitos da madeira com maior impacto no seu comportamento mecânico. No presente trabalho são analisados alguns critérios de avaliação da influência dos nós no comportamento mecânico de elementos de madeira. É analisada igualmente a possibilidade de utilização de um registo termográfico, obtido por meio de uma câmara de infravermelhos no decurso dos ensaios mecânicos, para uma melhor compreensão do efeito dos nós nesse mesmo comportamento. O estudo englobou o ensaio à compressão paralela às fibras de provetes de Pinho bravo apresentando uma gama variada de nós.Os resultados obtidos permitiram concluir que a utilização somente de critério relativos às características do nó explica cerca de 30 % da variabilidade observada nos resultados da resistência à compressão. Uma melhoria significativa (r2 0.60) foi obtida incluindo informação sobre as características da madeira limpa (massa volúmica). As imagens termográficas permitem uma melhor percepção da origem e propagação do dano, possibilitando que análises futuras mais exaustivas possam melhorar os modelos agora obtidos. Knots are one of the wood
Ano: 2011
Número Páginas:
10.
Autor(es): Santos, C. A.; Saporiti Machado, J.
Editor: Departamento de Engenharia Civil da FCTUC
Keywords: Kar; Maritime pine; Strength; Infrared; Kar; Pinho bravo; Resistência; Infravermelhos
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Avaliação do potencial fungicida eou fungistático dos extratos de Senna multijuga e Senna spectabilis (Fabaceae) contra fungos de podridão branca e castanha.
Com foco na busca por alternativas menos tóxicas para o controlo de fungos e insectos que deterioram a madeira, o presente trabalho trás os resultados obtidos em ensaios de triagem inicial para avaliação do potencial fungicida e/ou fungistático do extracto bruto de folhas de duas espécies botânicas nativas do Brasil. O método empregado neste estudo consistiu naimpregnação de discos de papel de filtro com diversas concentrações dos extractos de folhas de Senna multijuga e Senna spectabilis, ambas da família Fabaceae e o contacto destes com os fungos basidiomicetas Gloeophyllum trabeum e Pycnoporus sanguineus, responsáveis, respectivamente, por podridão castanha e branca da madeira. Os resultados obtidos apontampara o efeito inibitório de ambos os extractos e efeito fungistático de Senna multijuga. Focusing the search for less toxic alternatives for controlling fungi and insects that damage wood, this work presents the results obtained in initial screening tests for assessing the antifungal potential from the crude extract of leaves of two plant species natives from Brazil. The methodused in this study consisted in the impregnation of filter paper disks with various concentrations of extracts of leaves of Senna spectabilis and Senna multijuga, both from the family Fabaceae andcontact of them with the fungi basidiomycetes Gloeophyllum trabeum and Pycnoporus sanguineus, responsible respectively for brown and white rot. The results indicate the inhibitory effect of both extracts and the fungistatic effect of Senna multijuga.
Ano: 2011
Número Páginas:
8.
Autor(es): Monteiro, M. B.; Lina Nunes; Young, M. C.
Editor: Departamento de Engenharia Civil da FCTUC
Keywords: Brown rot; White rot; Antifungal activity; Senna spectabilis; Senna multijuga; Podridão castanha; Podridão branca; Atividade antifúngica; Senna spectabilis; Senna multijuga
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Livros
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Térmita-de-madeira-seca. West Indian drywood termite
N/A
Ano: 2019
Número Páginas:
144-145pp.
Autor(es): Duarte, S.; Lina Nunes
Revista: Guia Prático da Fauna Terrestre dos Açores
Editor: Instituto Acoriano da Cultura
Keywords: Cryptotermes brevis
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Térmita-de-pescoço-amarelo. Yellow-necked drywood termite; European drywood termite
N/A
Ano: 2019
Número Páginas:
146-147pp.
Autor(es): Duarte, S.; Lina Nunes
Revista: Guia Prático da Fauna Terrestre dos Açores
Editor: Instituto Açoriano da Cultura
Keywords: Kalotermes flavicollis
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Térmita-subterrânea-americana. Easten subterranean termite
N/A
Ano: 2019
Número Páginas:
148-149pp.
Autor(es): Duarte, S.; Lina Nunes
Revista: Guia Prático da Fauna Terrestre dos Açores
Editor: Instituto Açoriano da Cultura
Keywords: Reticulitermes flavipes
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Térmita-subterrânea-ibérica. Iberian subterrarean termite
N/A
Ano: 2019
Número Páginas:
150-151pp.
Autor(es): Duarte, S.; Lina Nunes
Revista: Guia Prático da Fauna Terrestre dos Açores
Editor: Instituto Açoriano da Cultura
Keywords: Reticulitermes grassei
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Estudo histórico e científico da Xiloteca da Academia das Ciências de Lisboa construída por José Aniceto Rapozo - nota preliminar
O Museu da Academia das Ciências de Lisboa possui uma preciosa xiloteca assinada pelo Mestre dos marceneiros portugueses, José Aniceto Rapozo contendo 1213 amostras de madeiras do Brasil e 12 de outras origens. A sua importância no progresso do conhecimento dos recursos florestais do Brasil naviragem dos séculos dezoito e dezanove conduziu ao estudo em curso. Dada a devastação verificada em vastas áreas florestais brasileiras, surgem dificuldades por certas espécies poderem ter distribuiçãogeográfica diferente (com eventual extinção, geral ou localizada), por insuficiência do material de comparação, e por ambiguidade das designações comerciais.Foi possível identificar esta xiloteca como uma de quatro encomendadas a Aniceto Rapozo pelo Príncipe Regente. A análise das amostras de madeira e a informação documental mostram que a colecçãotem por base uma remessa de 5008 amostras de madeiras do Brasil enviada em 1784 para o Arsenal Real do Exército, em Lisboa, pelo Vice-Rei do Brasil, Luís de Vasconcellos e Souza.O valor científico do conjunto é evidenciado pela identificação botânica das espéciesrepresentadas. Na situação actual, a identificação das espécies florestais representadas na amostragem foiinteiramente conseguida em 14% dos casos, conseguida mas ainda por confirmar em 27%. Dado o carácter preliminar deste estudo, os seus resultados serão ulteriormente publicados com mais pormenor. Among the Lisbon Academy of Sciences Museum collection there is a valuable xylarium by theleading Portuguese master cabinet-maker José Aniceto Rapozo (1756-1824), comprising 1213 wood samples from Brazil plus 12 from elsewhere. This collection is most important since it allows us to improve the knowledge on Brazilian forest resources by the end of the eighteenth century and thebeginning of the next. This study aims to establish its historical framework and scientific value. Owing tooverexploitation and even devastation of very large forest areas in Brazil, difficulties for our study aroseeither as some species may have now a different geographical distribution (and eventually may have underwent local or general extinction), by lack of adequate comparison material, or because of ambiguityof the commercial names.Results so far obtained allowed us to recognize the xylarium as one of the four commanded Rapozo by the Regent Prince, later King João VI (1767-1826). Taking into account the wood samples analyses as well as bibliographic data it is possible to conclude that the collection was prepared from a set 3 of 5008 Brazilian wood samples sent to the Royal Arsenal in Lisbon in 1784 by the Brazil
Ano: 2013
Número Páginas:
9.
Autor(es): Saporiti Machado, J.; Antunes, M.
Editor: Academia das Ciências de Lisboa (ACL)
Keywords: Identification; History; Brazil; Woods; Xylarium; Lisbon academy of sciences; Identificação; História; Brasil; Madeiras; Xiloteca; Academia das ciências de lisboa
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Capítulos de Livros
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A Review of Laboratory Tests to Evaluate Agro-Industrial Wastes Properties as Building Materials
This work collects information about laboratory tests to evaluate the properties of agro-industrial wastes used for thermal insulation building materials considering them individually and in composits. It focuses on bio-susceptibility, as one of the main aspects to consider for bio-based building products.
Ano: 2023
Número Páginas:
2p..
Autor(es): Cintura, E.; Lina Nunes; Faria, P.
Revista: Testing and Experimentation in Civil Engineering
Editor: Springer Nature
Volume:
Volume 41.
Keywords: Test methods; Bio-wastes; Bio-susceptibility; Bio-based materials
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Innovative Durability Tests on Construction Materials
Innovation in structures and construction materials demands a more accurate performance analysis during the life cycle. In addition, climatic changes pose new challenges to civil infrastructures that were not so relevant in the past. In most cases, the traditional test methods cannot accurately assess the complex phenomena involved in durability. The modern and complex factors require a different approach to durability analysis. The purpose of this chapter is to present innovative durability tests on construction materials: wood; rammed earth, cob and unfired blocks; natural stone; bituminous binders and mixtures; and Fibre Reinforced Polymers (FRP) to concrete bonded connections. Most of these tests concern the accelerated simulation of the main phenomena involved in durability performance
Ano: 2023
Número Páginas:
53-73pp..
Autor(es): Chastre, C.; Faria, P.; Neves, J.; Ludovico-Marques, M.; Biscaia, H.; Lina Nunes
Revista: Advances on Testing and Experimentation in Civil Engineering
Editor: Springer
Keywords: Performance; Innovation; Durability; ccelerated durability tests; Accelerated durability tests; Ageing techniques
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Optimisation of Production Parameters to Develop Innovative Eco-efficient Boards
Laboratory tests were carried out to define production parameters of innovative eco-efficient composites made up of hazelnut shells as aggregate and a sodium silicate solution as adhesive. The aim was to maximize the content of bio-aggregates and minimize the amount of adhesive, guaranteeing the feasibility of producing samples. Therefore, after preliminary testing, the percentages of hazelnut shells and the sodium silicate solution were kept constant: 70% and 30% of the total volume, respectively. However, the characteristics of the considered composites did not allow the production of uniform samples. The sodium silicate solution was not rapidly absorbed by the bio-aggregates; during the drying process, it was deposited on the bottom side of the samples. The uniformity of the samples is required to guarantee a correct evaluation of their performance and future homogeneous panels. Hence, different production parameters were investigated, such as drying at T
Ano: 2023
Número Páginas:
11p..
Autor(es): Cintura, E.; Faria, P.; Molari, L.; Lina Nunes
Revista: Bio-Based Building Materials
Editor: Springer
Volume:
Volume 45.
Keywords: Sodium silicate; Hazelnut shells; Bio-waste
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Testing Durability on Construction Materials
The durability of construction materials is a key concern and can be related to different actions such as weathering conditions outdoors enhanced by climatic change, chemical and biological attack, abrasion, and other conditions of service over time. Frequently, several actions develop simultaneously, making it difficult to reproduce in situ conditions in laboratory. Furthermore, testing to assess durability depends largely on the nature of the material itself or on the way it has been assembled with other materials. The ageing techniques to assess long-term durability performance of construction materials are based on accelerated durability tests, which include, for example, thermal stress, freeze
Ano: 2023
Número Páginas:
29-51pp..
Autor(es): Chastre, C.; Faria, P.; Neves, J.; Ludovico-Marques, M.; Biscaia, H.; Lina Nunes
Revista: Advances on Testing and Experimentation in Civil Engineering
Editor: Springer
Keywords: Wood; UV radiation; Frost; Weathering; Salts; Natural stone; Polymeric composites; Clayish materials; Cementitious composites; Brick; Bituminous binders and mixtures; Biological agents
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Structural gluing of portugueses timbers
This paper presents an overview of research carried out to assess the bonding suitability of Portuguese timbers.Most work developed in the last decades has focused Maritime pine timber, due to its traditional use in building construction, good mechanical properties and availability. Untreated, as well as preservative treated Maritime pine have been studied, as its impregnability allows deep treatment suitable for applications in Use Classes 3 and 4.Recent results on bonding preservative treated Maritime pine wood are discussed.Preliminary results regarding other species that are becoming available in the Portuguese market are also presented, as an attempt to reduce pressure on Maritime pine timber as well as to seek more valuable alternatives for their traditional uses.
Ano: 2018
Número Páginas:
171-183pp.
Autor(es): Cruz, H.; Martins, C.; Dias, A.
Revista: Timber: Bonds, Connections and Structures
Editor: Material Testing Institute (MPA), University of Stuttgart
Keywords: Structural gluing; Portuguese timbers
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Teses de Doutoramento
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Caracterização da aderência de varões nervurados sujeitos a ações repetidas e alternadas
No presente trabalho apresentam-se os resultados mais relevantes obtidos num programa experimental desenvolvido no LNEC com o objetivo de caracterizar a aderência dos varões nervurados do tipo A500NR SD existentes no mercado, fundamentalmente para melhorar a modelação do comportamento dos elementos de betão armado de zonas críticas de estruturas inseridas em zonas sísmicas.O programa experimental desenvolvido pretende simular as condições de aderência existentes num varão horizontal de uma ligação viga-pilar e tem como principais variáveis varões de dois diâmetros frequentemente utilizados (16 e 25 mm), dois níveis diferentes de área relativa das nervuras (A e B) e duas classes de betão (C1 e C2), ambos representativos do betão utilizado nas construções mais relevantes.Os resultados obtidos quer nos ensaios monotónicos quer nos ensaios cíclicos apontam para um decréscimo da tensão de aderência com o aumento do diâmetro da ordem dos 10%. O aumento da área relativa das nervuras transversais traduz-se num incremento da tensão máxima de aderência da ordem dos 15%, com uma redução do deslizamento que ronda os 15%. Nesse sentido, este estudo propôs que, no caso dos varões com maior área relativa das nervuras, a tensão de aderência máxima possa variar entre 2,35 e 2,65 vezes a raiz quadrada da resistência do betão à compressão e que o patamar onde a tensão de aderência é máxima se situe entre 0,5 e 1,5 mm de deslizamento.Explorou-se também o fenómeno da entrada em cedência da armadura tendo-se concluído que, em provetes que pretendem simular as condições de aderência existentes num varão horizontal de uma ligação viga-pilar, a entrada em cedência da armadura conduz a uma redução da tensão de aderência máxima inferior a 10%, quer regime monotónico quer em regime cíclico.
Ano: 2014
Número Páginas:
435p.
Autor(es): Louro, A. S.
Keywords: Estudo experimental; Modelação analítica; Ações repetidas e alternadas; Varões nervurados; Aderência
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Tratamento e consolidação de madeira de pinho degradada em elementos estruturais de edifícios antigos
O presente trabalho de investigação refere-se à conservação de elementos estruturais de madeira medianamente degradados por fungos em edifícios antigos. Propõe-se estudar a compatibilidade entre produtos de tratamento e de consolidação por impregnação, aplicados sequencialmente. A avaliação do processo foi realizada maioritariamente em laboratório e na óptica do desempenho mecânico conjunto da madeira e produtos aplicados, por intermédio de ensaios físico-mecânicos destrutivos e não destrutivos e também por ensaios mecânicos não destrutivos realizados in situ. Foram utilizados produtos comerciais, aplicando-os às espécies de madeira correntemente encontradas nos edifícios antigos da zona de Lisboa: Pinho bravo e Casquinha. Procedeu-se à avaliação mecânica de madeira nova e antiga, em estado são e degradado; ao desenvolvimento de um método de medição da profundidade de penetração de produtos de tratamento; à avaliação da capacidade consolidante de madeira degradada por produtos poliméricos fluidos e à avaliação da sua actuação conjunta, estudada com e sem envelhecimento artificial. Os resultados obtidos indicaram significativos aumentos de capacidade mecânica da madeira degradada, quando submetida a tratamento e consolidação Este trabalho desenvolve, assim, uma proposta de solução para a madeira que não se encontra sã, mas que ainda possui capacidade resistente, não necessitando, por isso, de ser removida. O processo de tratamento e consolidação promove resistência aos agentes biológicos e, simultaneamente, recuperação de alguma resistência mecânica da madeira, conferindo-lhe capacidade para continuar em serviço.
Ano: 2011
Número Páginas:
404
Autor(es): Henriques, M. D.
Keywords: Elementos estruturais; Resistência mecânica; Tratamento; Consolidação; Edifícios antigos; Conservação; Degradação por fungos; Madeira
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Foraging ecology of Reticulitermes grassei (clément) with re feren ce to its management as a pest of timber
Subterranean termites from the genus Reticulitermes are an important pest ofwood in service throughout southern Europe and elsewhere. For effective termitecontrol with long term protection but minimal environmental damage, newintegrated approaches to termite management are needed. Baiting-based systemsseem to be promising non-traditional methods for termite control, targeting thecolony as a whole. However, control through baiting is only feasible when it isknown that the toxicant can be transferred to all the colonies foraging on theinfested area and also throughout each individual colony. Accordingly, the workdescribed is specifically designed to achieve a better understanding of thedistribution and delimitation of colonies within a population of Reticulitermes,with parallel insights into foraging behaviour and colony organization.Initially, the species/subspecies spectrum present within the notionalReticulitermes group in Portugal was reassessed. It was shown that Reticulitermesgrassei is the only species encountered. Foraging activity was then assessed in anexperimental woodland site over two successive annual cycles, both by thesampling of natural lying dead wood and by a standard baiting grid. R. grasseiseem to select wood with larger diameter, with an apparent preference for materialalready decayed by fungi. Both termite and fungal attack on wood seems to bepromoted by higher moisture levels, such as prevail in larger litter items andduring seasonal rains. Termites were unable to detect and direct their foragingtowards sound wood in laboratory conditions, suggesting that the network ofinfochemical signals is more complex than just volatiles emanating from soundwood. Mark-release-recapture (MRR) was used to delineate foraging groups,which were then allocated to their parent colonies by the use of microsatellitemarkers. The results suggest that resource sharing is a facultative behaviour,specifically when food is not a limiting factor for colony development. Theimplications of all these findings for bait technology and protocols are discussed,with reference to the local population ecology of Reticulitermes.
Ano: 2009
Autor(es): Nobre, T.
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Relatórios
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Project
The project CircularBuild -
Ano: 2023
Autor(es): Lina Nunes; Duarte, M.; Duarte, S.
Keywords: Moulds; Biological durability; Subterranean termites; Decay fungi; AGEPAN® DWD PROTECT
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Monitor
Relatório final do projeto PTDC/ECM/099121/2008
Ano: 2014
Autor(es): Lina Nunes; Duarte, S.; Saporiti Machado, J.
Keywords: Deteção; Monitorização; Térmitas subterrâneas; Uso sustentável de estruturas de madeira
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Materiais metálicos. Ensaio de tracção. 2ª Parte: Verificação do sistema de medição da força da máquina de ensaio de tracção. Projecto de versão portuguesa da Norma Europeia EN 10002-2 (1991)
O presente trabalho apresenta um projecto de versão portuguesa da Norma Europeia EN 10002-2, e insere-se numa série de estudos programados pelo autor, enquanto coordenador da normalização nacional no domínio dos ensaios mecânicos, físicos e não-destrutivos de materiais metálicos.O texto do projecto de norma apresentado consiste na versão final de uma proposta redigida pelo autor, na sequência dos estudos efectuados ao nível da Comissão Técnica de Normalização competente.
Ano: 1992
Autor(es): Baptista, A. M.
Keywords: Normalização; Ensaio de tracção; Materiais metálicos
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Materiais metálicos. Ensaio de tracção. 5ª Parte: método de ensaio a temperatura elevada. Projecto de versão portuguesa da Norma Europeia EN 10002-5 (1991)
O presente trabalho apresenta um projecto de versão portuguesa da Norma Europeia EN 10002-5, e insere-se numa série de estudos programados pelo autor, enquanto coordenador da normalização nacional no domínio dos ensaios mecânicos, físicos e não-destrutivos de materiais metálicos.O texto do projecto de revisão apresentado consiste na versão final de uma proposta redigida pelo autor, na sequência dos estudos efectuados ao nível da Comissão Técnica de Normalização competente.
Ano: 1992
Autor(es): Baptista, A. M.
Keywords: Normalização; Ensaio de tracção; Materiais metálicos
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Metrologia de Forças. Participação do LNEC no 2nd WECC Audit on Force Measurement
O presente relatório descreve a participação do LNEC no programa europeu de intercomparação de calibrações de forças
Ano: 1992
Autor(es): Baptista, A. M.
Keywords: WECC Audit; Metrologia de forças
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Materiais metálicos. Arames. Ensaio de enrolamento. Projecto de revisão da NP 850 (1985)
O presente trabalho apresenta um projecto de revisão da Norma Portuguesa NP 850 (1985)
Ano: 1991
Autor(es): Baptista, A. M.
Keywords: Ensaio de Enrolamento; Arames; Materiais metálicos
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Materiais metálicos. Ensaios de resistência mecânica. Símbolos. Projecto de revisão da NP 386 (1965)
O presente trabalho apresenta um projecto de revisão da Norma Portuguesa NP 386 (1965)
Ano: 1991
Autor(es): Baptista, A. M.
Keywords: Normalização; Simbologia; Ensaios mecânicos; Materiais metálicos
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Materiais metálicos. Tubos. Ensaio de Abocardamento. Projecto de revisão das NP 449 (1966) e NP 451 (1966)
O presente trabalho apresenta um projecto de revisão das Normas Portuguesas NP 449 (1966)
Ano: 1991
Autor(es): Baptista, A. M.
Keywords: Normalização; Ensaio de Abocardamento; Tubos; Materiais metálicos
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Materiais metálicos. Tubos. Ensaio de Achatamento. Projecto de revisão da NP 450 (1966)
O presente trabalho apresenta um projecto de revisão da Norma Portuguesa NP 450 (1966)
Ano: 1991
Autor(es): Baptista, A. M.
Keywords: Normalização; Ensaio de Achatamento; Tubos; Materiais metálicos
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Materiais metálicos. Tubos. Ensaio de Dilatação de Anéis. Projecto de Norma Portuguesa
O presente trabalho apresenta um projecto de Norma Portuguesa relativo ao ensaio de dilatação de anéis de tubos metálicos, e insere-se numa série de estudos programados pelo autor, enquanto coordenador da normalização nacional no domínio dos ensaios mecânicos, físicos e não-destrutivos de materiais metálicos, com a finalidade de preencher lacunas da Normalização Portuguesa neste domínio que a indústria e as instituições ligadas ao controlo da qualidade considerem ser mais urgente colmatar.O texto apresentado consiste na versão final de uma proposta redigida pelo autor, na sequência dos estudos efectuados ao nível da Comissão Técnica de Normalização competente.
Ano: 1991
Autor(es): Baptista, A. M.
Keywords: Normalização; Ensaio de dilatação de anéis; Tubos; Materiais metálicos
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Outros
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VARÃO NERVURADO CODIMETAL (A500 ER)
N/A
Ano: 2009
Número Páginas:
2pp.
Autor(es): DE/NCE
Keywords: Varão nervurado; Varão para betão armado
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Zumarraga 500SD (A500 NR de Ductilidade Especial)
N/A
Ano: 2009
Número Páginas:
2pp.
Autor(es): DE/NCE
Keywords: Ductilidade; Varão nervurado; Varão para betão armado
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CONTRAPLACADO MARÍTIMO CARACTERÍSTICAS E CERTIFICAÇÃO
N/A
Ano: 2008
Número Páginas:
8pp.
Autor(es): DE / NEM
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