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Poplar wood is a light, soft, and fast-growing timber from a hardwood species, characteristics that make it suitable for several applications. This study focused on the mechanical characterization of Portuguese poplar species, namely white poplar (Populus Alba) and black poplar (P. nigra), aiming for its structural use. Therefore, a sample of lamellae was assessed to determine its density and dynamic modulus of elasticity, using a non-destructive device, based on longitudinal vibrations. Clear wood specimens were obtained from a set of lamellae to perform tension and compression parallel-to-grain tests. These tests were used to determine the moduli of elasticity in tension and compression and the tensile and compressive strengths and strains. Also, typical stress-strain curves were identified for the sample studied. The results stressed the potential for structural applications of Portuguese poplar.

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Four types of sandwich panels with multilayered designs were produced using wood veneer of Aleppo pine as face and inner sheets, and cork agglomerate as core,intended for use in construction as panelling or partition walls in interior applications. These multilayered sandwich panels were characterized regarding static hardnessand dimensional stability when facing changes in relative humidity and when subjected to a deformation. The panels showed a considerable increase in dimensional stability and shear strength with the increase of the number oflayers. The results suggest that the correct design choice, for example number of inner wood sheets and thickness of cork core layers, allows these sandwich panels to be used as non-structural construction elements such as partition walls.

Changes in flagellate protist communities of subterranean termite Reticulitermes gras-sei across different locations were evaluated following four predictions: (i) Rural endemic (Portugal mainland) termite populations will exhibit high diversity of symbionts; (ii) invasive urban populations (Horta city, Faial island, Azores), on the contrary, will exhibit lower diversity of symbionts, showing high similarity of symbiont assemblages through environmental filtering; (iii) recent historical colonization of isolated regions

This paper describes the use of non-destructive methods to assess the mechanical properties of structural glued laminated timber made from poplar. The longitudinal vibration method and transformed section method were considered. Full-scale tests were also performed to determine the most relevant mechanical properties of 18 beams, namely modulus of elasticity and bending strength. In addition, the bonding performance of each beam was checked by delamination and shear strength tests. Detailed analysis of the results was performed and combined with Levene's and Tukey's tests. The accuracy of the two non-destructive test methods was evaluated by linear regression analysis. The transformed section method showed stronger correlations with modulus of elasticity and shear strength. Slightly lower values were presented by the longitudinal vibration method. A strength class of GL24c can be assigned for glued laminated poplar made with timber with lower properties at the inner lamellas.

Pine (Pinus pinaster Ait.) wood samples were subjected to a combined treatment by densification and heat treatment. Samples were densified before and after heat treatment. The heat treatment was made inside an oven at 190ºC during 2 to 6 h and wood densification was made in a hot press at around 48 bar pressure and temperatures between 160ºC and 200ºC for 30 min. Compression-set, compression-set recovery after three cycles of water soaking followed by oven drying, density, hardness, bending strength and stiffness and durability against subterranean termites were determined after the treatment. Results show that densification increases density, hardness, bending strength, stiffness and durability against termites. Heat treatment applied after the densification is more effective in reducing compression-set recovery than if applied before.

The ability of subterranean termites to digest lignocellulose relies not onlyon their digestive tract physiology, but also on the symbiotic relationshipsestablished with flagellate protists and bacteria. The objective of this workwas to test the possible effect of different cellulose-based diets on the communitystructure (species richness and other diversity metrics) of the flagellateprotists of the subterranean termite Reticulitermes grassei. Termitesbelonging to the same colony were subjected to six different diets (naturaldiet, maritime pine wood, European beech, thermally modified Europeanbeech, cellulose powder and starvation), and their flagellate protist communitywas evaluated after the trials.All non-treated sound woods produced similar flagellate protist communitiesthat were more diverse and of high evenness (low dominance).On the contrary, flagellate protist communities from cellulose-fed termitesand starving termites were considered to be significantly different from allnon-treated woods; they were less diverse and some morphotypes becamedominant as a consequence of flagellate protist communities having sufferedmajor adaptations to these diets. The flagellate protist communitiesof untreated beech and thermally modified beech-fed termites were consideredto be significantly different in terms of abundance and morphotypediversity. This may be caused by a decrease in lignocellulose qualityavailable for termites and from an interference of thermally treated woodwith the chemical stability of the termite hindgut.Our study suggests that as a consequence of the strong division oflabour among these protists to accomplish the intricate process of lignocellulosedigestion, termite symbiotic flagellate protist communities are adynamic assemblage able to adapt to different conditions and diets. Thisstudy is important for the community-level alteration approach, and it isthe first study to investigate the effects of thermally modified wood on theflagellate protist communities of subterranean termites.

Serviceability limit states (related to deformation) rather than ultimate limit states (related to collapse)are often the reason for the need to assess existing timber structures. Prediction of timber members

Monitoring and evaluation of glued laminated timber structures in service is essential to warrant its integrity, where non-destructive techniques play an important role. This paper describes the results obtained on glued laminated timber beams of maritime pine, with and without preservative treatment, and of spruce, exposed to naturaloutdoor environment as well as to artificial weathering. The assessment of glue lines

This paper presents work carried out with the aim of characterizing the mechanical behavior and developing visual and machine strength grading systems for Portuguese maritime pine roundwood for structural applications. Two samples of forty maritime pine logs each were collected, one in a northern region of Portugal and another in an interior central region. After drying, the logs were visually graded andsubjected to nondestructive tests, using vibration and ultrasounds, for determination of dynamic modulus of elasticity. The logs were then subjected to destructive tests for determining bending and compression strength and bending modulus of elasticity. These results were analyzed in order to identify the features to be considered in the strength grading process. From this analysis, a proposal was developed tovisually grade Portuguese maritime pine roundwood in two strength grades. According to the European strength class standard for solid timber, the upper grade has similar mechanical properties to the C50 class, whereas the lower grade is similar to the C35. The machine grading showed good potential as a result of the good correlation presented between the dynamic modulus of elasticity and the mechanical properties. However, the ultrasounds showed slightly better correlation than the vibration method, whereas the last one is more practical.

Delamination at the glue lines is one key factor to take into account when assessing glued laminated timber members in service. In order to gain a more objective and wide knowledge about the importance of delamination relative to its type and extension, a numerical study was developed.Finite element modeling (FEM) was used to evaluate the delamination influence (near the surface, on the vertical faces and ends) on the mechanic performance of straight glued laminated timber beams. The FEM was validated by comparing stresses and deformations obtained with the modeland with the application of the beam theory, showing satisfactory results.Results show that when delamination is non-symmetric regarding the member

A durabilidade da madeira ao ataque de térmitas é um critério muito importante na escolha da madeira aplicada em áreas onde a presença de térmitas subterrâneas foi diagnosticada.Testes com e sem escolha foram efectuados para investigar as preferências alimentares de Reticulitermes grassei relativamente a duas espécies autóctones (Pinus pinaster

Timber constructions are often built in combination with other materials such as concrete.These materials can influence the timber construction. Moist concrete can e.g. lead todevelopment of molds which creates an unhealthy living area for people. Furthermore, moisture in wood buildings can negatively affect the wood material, which can lead to negative biological activity in timber and possible reduction of strength properties of timber constructions.The present paper introduces a new innovative method of timber protection and describes the influence of moisture on wood and concrete.The new environmental friendly system for protection of timber has been tested on wooddestroying fungi and termites. It can be shown that wood protection by means of electro osmotic pulsing technology can preserve wood in laboratory trials. The wood moisture content is reduced when the protection system is installed. Trials on protected wood against subterranean termites showed lower wood moisture content after test of protected samples compared to untreated samples. However, termite activity could not be reduced to a larger extend as the termite living surroundings were not included.It could be shown that humidity in pores of concrete in cellar walls is reduced usingelectro osmotic pulsing. The drying of concrete when combined with timber constructions can additionally help to reduce timber degradation as all protection measures that lead to a drier building are positive for fungi and subterranean termite control.

No presente trabalho serão descritas algumas soluções para a consolidação ou reforço deelementos estruturais de madeira utilizando diferentes técnicas. Serão descritos os procedimentos e cuidados a ter na sua execução, ao mesmo tempo que serão referenciadas as principais vantagens e desvantagens. Assim, dependendo do grau de eficácia pretendido, capacidade económica ou intrusividade da solução é possível distinguir e tipificar algumas soluções.A utilização de madeira nova na reabilitação de soluções existentes consiste numa intervenção mínima que pretende manter, por vezes com carácter temporal, a estabilidade do elemento sem modificar o seu estado actual. São soluções económicas cujo resultado estético e muitas vezes funcional pode não ser o melhor. Um dos principais problemas é a degradação biótica dos apoiosjunto das paredes de suporte. Outros problemas como a deformação excessiva ou empenos grosseiros resultantes dos ciclos de presença-ausência de humidade nos elementos são outros fenómenos que potenciam esta situação. The present paper will describe some solutions for the consolidation or reinforcement of wooden structural elements using different techniques. It will be described the procedures and care in itsexecution, while the main advantages and problems are referenced. Thus, depending on the effectiveness, economic capacity or intrusiveness of the solution will be possible to distinguish and typify some solutions.The use of wood in the rehabilitation of existing solutions consists of a minimum intervention that intends to maintain the structural stability of the element without changing its current loading state.These solutions are mostly thought using an economic point of view which results in anesthetic and dysfunctional solutions. One of the main problems is precisely the biotic degradation of the supports. Other problems such as excessive deformation or warping resulting from cycles of presence-absence of moisture in the elements are other phenomena that enhance this situation.

No presente trabalho irão ser descritas algumas soluções para a consolidação e/ou reforço de elementos estruturais de madeira utilizando diferentes técnicas, em função dos materiais utilizados: betão armado e elementos metálicos. Irão ser analisadas a possibilidade de introduzir elementos em betão armado e elementos/perfis metálicos, no reforço de elementos solicitadosprincipalmente em flexão. Serão também analisadas as possibilidades de reforço e/ouconsolidação de pilares e coberturas.Deste modo, serão descritas algumas soluções que permitirão aumentar a capacidade portantedos elementos ou do conjunto, sugerindo formas práticas de executar convenientemente algumas destas propostas.Com o desenvolvimento tecnológico ao nível dos materiais e das técnicas de produção eexecução, o processo de reabilitação e recuperação dos pavimentos de madeira ganhou novo fôlego com a introdução de perfis metálicos e elementos de betão armado. The present work will describe some solutions for the consolidation and/or reinforcement of structural timber elements using different techniques taking into account the reinforcement materials used: concrete and steel. Will be also analyzed the possibility of introducing reinforcedconcrete and steel elements in the retrofitting of in bending wooden structures or elements. Finally, the possibilities of strengthening and/or consolidation of wooden columns and wooden roofs will be studied.Some solutions that increase the load bearing capacity of elements or structures will be described, and some practical issues will be presented. With the most recent technological development in materials and production techniques, the global process of rehabilitation and restoration of wooden floors gave new opportunities to the introduction of steel and reinforcedconcrete elements as a true solution.

Mesmo em aplicações não estruturais, a montagem e a fixação de componentes de madeira devem ser suficientemente fortes para garantir o seu adequado desempenho. Relativamente à madeira modificada, um aspecto pouco estudado é precisamente o desempenho das ligações realizadas com este material, designadamente a sua capacidade de retenção de ligadores metálicos e o desempenho de ligações ao corte.Foram realizados ensaios para avaliar a resistência ao arrancamento de parafusos e aresistência ao esmagamento de madeira comercial termicamente modificada. Os resultados destes ensaios foram comparados com os obtidos, no mesmo estudo, sobre madeira não modificada e confrontados com as expressões relevantes dadas no Eurocódigo 5.Verificou-se que a resistência ao esmagamento localizado da madeira modificada aumenta com a sua massa volúmica, numa tendência semelhante à observada em madeira não modificada. No entanto, é subestimada pelas expressões dadas no Eurocódigo 5, o que pode ser parcialmente explicado pelo menor teor de água de equilíbrio atingido pelo Thermowood®. Em contrapartida, aresistência ao arrancamento obtida em ensaios sobre este material foi semelhante à prevista pelo Eurocódigo 5 (EN 1995-1-1:2004/A1:2008) para madeira não modificada. Even in non-structural applications, timber components must be adequately fixed to ensure suitable performance. However, the performance of joints made with modified wood has not been adequately studied, namely regarding their axial and lateral load-carrying capacity.Tests were carried out to assess the embedding strength and the withdrawal strength of Thermowood®. These test results were compared to the ones obtained on untreated wood and checked against the equations given in Eurocode 5.It was concluded that the embedding strength of Thermowood® increases with its density, similarly to the trend found in untreated wood, but this is underestimated by the equations given inEurocode 5, partially as a consequence of the Thermowood® lower equilibrium moisture content. The withdrawal resistance measured in Thermowood® specimens was similar to the one predicted by Eurocode 5 (EN 1995-1-1:2004/A1:2008) for untreated wood.

. O presente trabalho apresenta um critério de interacção entre esforços para o cálculo do estado limite plástico de secções rectangulares de aço (barras e placas), submetidas a um esforço normal e a flexão desviada. Este critério foi obtido através da integração exacta da distribuição de tensões na secção. As suas principais vantagens residem na sua simplicidade, na sua precisão e no facto de estabelecer uma relação directa entre os esforços internos, a geometria da secção (relação altura-largura) e a direcção e posição do respectivo eixo neutro. Estas vantagens permitem a sua aplicação ao cálculo plástico de outras secções correntes na construção metálica, tais como os perfis em I ou de secção rectangular oca, por exemplo.

At the conservation and/or rehabilitation stage of a building the condition state of the timber structural elements strongly limits the actions to be adopted. A non-destructive survey of their state is therefore a frequent need. Due to their handling facility and the direct results obtained two inspection and diagnosisless-destructive or non-destructive tests (NDT) [Machado & Cruz, 1997] gain relevance in the in situ characterization of timber properties: the Pilodyn® and the Resistograph® methods.This paper presents the experimental procedures and the results obtained to find a possible correlation between the results obtained with these test readings and some properties of timber. The results werecorrelated with the density and the compression strength of two different species of pine timber with different ages, frequently used in buildings in the Lisbon area in the two last centuries. Thus, the following test campaigns were performed in Pinus sylvestris samples with approximately 80 and 150 years and recent Pinus pinaster samples: i- density; ii - compressive strength; iii - Pilodyn® and Resistograph® readings.Though further work is envisaged, a correlation was found between the timber properties and the valuesobtained with the non-destructive equipments used.

A madeira modificada é, hoje em dia, uma alternativa à madeira maciça para diversasaplicações na construção. A modificação da madeira baseia-se em processos de tratamentoaplicados de modo a melhorar o comportamento da madeira maciça, de forma a obviar alguns dos aspectos responsáveis por um desempenho desadequado da madeira na construção. Ostratamentos actualmente existentes, focam a sua atenção na melhoria da resistência àbiodegradação, da estabilidade dimensional e da resistência à radiação ultravioleta.O presente artigo tem por objectivo analisar as potencialidades da utilização da madeiramodificada na construção, salientando as suas vantagens e igualmente aspectos que têm limitado a sua utilização. A principal característica da madeira modificada é a drástica redução do teor de água de equilíbrio da madeira, propriedade importante sobretudo quando utilizada em situações de interior húmido ou exterior abrigado. Esta propriedade poderá favorecer a durabilidade da madeira modificada relativamente à madeira maciça. A melhor estabilidade dimensional reduz a formação de fissuras, conduzindo a um melhor desempenho dos sistemas de revestimento. No entanto, alguns tratamentos podem diminuir algumas propriedades da madeira com impactodirecto no nível de desempenho dos elementos na construção (resistência à flexão, o módulo de elasticidade e a densidade). Modified wood is, nowadays, an alternative to solid wood for various applications in construction.Wood modification treatments are processes used to improve the behaviour of solid wood in order to remedy some of the things responsible for an inadequate performance of wood in construction.Existing treatments focus their attention on the improvement of resistance to biodegradation,dimensional stability and resistance to ultraviolet radiation. This article aims to study the potential use of modified wood in construction, highlighting their benefits and also aspects that have limitedtheir use. The main feature of modified wood is the drastic reduction of water content of wood, an important property especially when wood is used in indoor humid or exterior protected conditions.This property can favour the durability of modified wood against solid wood. The better dimensional stability reduces the formation of cracks, leading to better performance of the coating systems.However, some treatments may decrease wood properties with direct impact on the level of performance of the elements in construction (namely bending strength, modulus of elasticity and density).

A utilização de madeira tratada de Pinho bravo nacional (Pinus pinaster Ait.) no fabrico de estruturas lameladas coladas parece ser uma alternativa interessante para situações de aplicação que requeiram madeira com grande durabilidade natural ou conferida. No entanto, de acordo com estudos anteriores realizados no LNEC, os elementos lamelados colados realizados com madeira de Pinho bravo tratada em profundidade apresentaram boa resistência mecânica, mas manifestaram tendência para delaminar, o que implica cuidados especiais no seu fabrico.Neste trabalho pretendeu-se avaliar a viabilidade da colagem de madeira de Pinho bravo não tratada e tratada em profundidade com dois produtos preservadores à base de azóis de cobre adequados à Classe de Risco 3. Procurou-se igualmente verificar a viabilidade da utilização de promotores de adesão para melhorar a resistência e a durabilidade (resistência à delaminação) de vigas de madeira lamelada colada de Pinho bravo.O trabalho experimental realizado envolveu a execução de vigas de pequena dimensão usando madeira de Pinho bravo não tratada e tratada em profundidade com dois tipos de produto preservador, usando uma cola adequada a ambiente exterior (tipo PRF) e aplicando previamente à colagem um promotor de adesão (n-HMR).O efeito dos diversos parâmetros considerados no estudo foi avaliado mediante ensaios de corte e de delaminação pela junta de colagem e os resultados obtidos foram bastante satisfatórios. Verificou-se que a cola utilizada e o processo de fabrico seguido permitiram obter juntas coladas com bom desempenho, mesmo sem recurso ao promotor de adesão.Adicionalmente, concluiu-se que a utilização de ambos os produtos preservadores à base de azóis de cobre, com e sem boro, parecem ser alternativas viáveis em termos de compatibilidade com a colagem, dada a sucessiva proibição dos tradicionais produtos preservadores da madeira no espaço Europeu. The use of preservative treated Maritime pine (Pinus pinaster Ait.) timber in the manufacture of glued laminated timber structures seems as interesting alternative for applications that require high natural or acquired durability.However, according with previous studies carried out at LNEC, glulam members produced from deep treated Maritime pine timber presented high strength but a tendency to delaminate, thus requiring special care in their manufacture.This study aimed to evaluate the viability of using adhesion promoters to improve strength and durability (delamination strength) of glulam beams made from Maritime pine timber, either untreated or treated for use in service class 3 (uncovered exterior) applications.The experimental work developed involved the fabrication of small length beams using Maritime pine timber, both untreated and impregnated with two types of preservatives, using an adhesive suitable for external environments (PRF type) and applying an adhesion promoter (n-HMR) to timber prior to gluing.The effects of several parameters considered in this study were evaluated by shear and delamination tests of the glue lines. Even in the case of glulam made without the adhesion promoter the test results were very good, showing the suitability of this specific PRF adhesive for the job.Additionally, it was concluded that the use of new preservative products based on copper azole formulations is a viable alternative, given the progressive restrictions to traditional wood preservatives in the European market.

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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

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.

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

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

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

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.

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.

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.

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.

O presente trabalho apresenta um projecto de Norma Portuguesa relativo ao ensaio de dureza Vickers (HV0,2 a HV5 exclusive) de materiais 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, a fim de actualizar as Normas Portuguesas existentes neste domínio.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.

O presente trabalho apresenta um projecto de versão portuguesa da Norma Europeia EN 10002-1, 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, a fim de actualizar as Normas Portuguesas existentes neste domínio.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.

O presente trabalho consiste no relatório de uma missão a Paris do signatário, na sua qualidade de coordenador da Normalização Nacional no domínio dos "Ensaios mecânicos, físicos e não-destrutivos de materiais metálicos", a fim de representar Portugal numa reunião do ECISS/TC 1a "Ensaios mecânicos e físicos de aços", encarregado dos trabalhos de Normalização Europeia neste domínio.

O presente trabalho pretende mostrar as possibilidades fornecidas pela utilização de um método de simulação no estudo da homogeneidade da fiabilidade, oferecida pelas curvas de encurvadura de colunas, de diferentes regulamentos de estruturas de aço.Através de um modelo geometricamente não linear, de que se faz uma breve apresentação e se descrevem alguns exemplos de aplicação, é feito o estudo da carga crítica de encurvadura de um perfil IPE 120, segundo o eixo de maior inércia. Os resultados apresentados referem-se a cerca de 1000 colunas diferentes, obtidas através de um método de simulação do tipo Monte-Carlo, para as quais se efectua a comparação entre os valores da carga crítica obtidos e os fornecidos por vários regulamentos, bem como a análise da homogeneidade da fiabilidade conferida pelos mesmos regulamentos em função das respectivas esbeltezas.

O presente trabalho apresenta um projecto de Norma Portuguesa com o título

O presente trabalho apresenta um projecto de Norma Portuguesa com o título

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