Publications

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.

Os elementos de inércia variável podem fornecer soluções interessantes, sob os pontos de vista estético e económico, para pilares de estruturas de aço. A verificação da sua segurança apresenta-se, no entanto, mais complexa que no caso dos elementos de secção uniforme, nomeadamente no que se refere ao cálculo da respectiva carga crítica, por exemplo. O presente trabalho propõe alguns métodos simplificados para a determinação da carga crítica destes elementos estruturais, através da utilização de tabelas aplicáveis ao cálculo de pilares com diferentes características geométricas e vários tipos de apoio nas suas extremidades.

O trabalho que ora se apresenta constitui uma visão enquadradora da prevenção de acidentes profissionais no sector da construção civil e obras públicas, tendo por base os referenciais estruturantes definidos pela comunidade técnica e científica. Estes princípios, defendidos pela doutrina da Organização Internacional do Trabalho, instituições da União Europeia e organizações públicas portuguesas com responsabilidades no âmbito da prevenção de riscos e doenças profissionais, têm vindo a ser vertidos nos quadros normativos vigentes (normas jurídicas, técnicas e éticas). Mais do que identificar disfunções, apresenta-se um exemplo de um modelo integrado de boas práticas, da fase de projecto, passando pela fase de trabalhos em estaleiro e terminando na fase de conservação e manutenção de um conjunto de edifícios para habitação e comércio.

This paper presents an analytical elastic-plastic model to study steel I-shaped cross-sections bent over their weak axis. The basic variables are the cross-section global deformations from which it is possible to evaluate the internal loads and the cross-section stiffness terms by means of a set of simple mathematical relationships. The model allows the yield spreading across the sections as well as the effects of the strain hardening and global deformations interaction to be taken into account on the non-linear cross-section behaviour in the elastic-plastic domain. The section failure by excessive deformation of its most strained fibres may also be directly controlled by these expressions. This model represents an efficient, simple and accurate alternative to the models based on the analysis of the cross-section by means of numerical integration over the cross-section divided into elementary fibres or layers.

An analytical model allowing the mechanical behaviour of simply supported beams under concentrated transversal loads to be evaluated, is presented in this paper. The beams are made of I-sections. The constitutive material is supposed to present an elastic-perfectly-plastic behaviour. The cross-sections displacements and rotations are evaluated through analytical expressions presented for the beam elastic and elastic-plastic domains; this last being divided into two different phases, when the flanges are partially yielded as the web remains elastic, or when yielding progresses across the webs of the most strained sections, after complete yielding of the flanges. These analytical relationships allow also the evolution of the yielded areas, along the beam cross-sections and length, as a function of the applied load, to be controlled.

Tapered members are an efficient solution for steel beams, allowing an adjustment of the cross-sections resistance to the applied loads. However, while the critical cross-section of uniform beams is always the one subjected to the most unfavourable load combination, it is not the case with tapered beams, since both acting and resistant values of the cross section internal loads vary along the beam length. So, one of the main problems in the design of these structural members lies on the determination of the beam critical cross-section where yielding occurs for the first time. This paper presents a method of calculation of analytical expressions for the elastic design of tapered beams subjected to bending and axial force. These relationships allow the beam critical section, its internal forces and the maximum loads carried by the beam at its elastic limit state, to be determined. Some examples are presented to show the possibilities of this proposal.

Tapered members are an efficient solution for steel beams, allowing an adjustment of the cross-sections resistance to the applied loads. However, while the critical cross-section of uniform beams is always the one subjected to the most unfavourable load combination, it is not the case with tapered beams, since both acting and resistant values of the cross section internal loads vary along the beam length. So, one of the main problems in the design of these structural members lies on the determination of the beam critical cross-section where yielding occurs for the first time.This paper presents a method of calculation of analytical expressions for the elastic design of tapered beams subjected to bending and axial force. These relationships allow the beam critical section, its internal forces and the maximum loads carried by the beam at its elastic limit state, to be determined. Some examples are presented to show the possibilities of this proposal.

This paper presents an analytical model to evaluate cross-section rotations and displacements in a cantilever beam subjected to a concentrated transversal load at its free end. The beam is made of an I-section, and its material is expected to follow an elastic-perfectly-plastic behaviour. The cross-section displacements and rotations may be evaluated by means of analytical expressions, which are presented both for the beam elastic and elastic-plastic domains. The latter is divided in two different phases: when only a portion of the flanges is yielded, the web remaining elastic, and when yielding progresses across the web of the most strained sections, after total yielding of their flanges. These analytical expressions also allow the evolution of the yielded areas to be controlled, along the beam cross-sections and length, as a function of the applied load.

This paper presents a method of evaluation of the elastic critical load of tapered members with circular and square cross-sections, under simple compression. The cross-sections of these members may be full solid or hollow, with constant wall thickness, and their external dimensions linearly vary between the column ends. This method is an adaptation of Euler

O presente trabalho visa a divulgação de informação estatística sobre a sinistralidade em trabalhos de construção civil e obras públicas, com especial destaque para a evolução do número de acidentes mortais ao longo da última década. Descreve-se a distribuição destes acidentes em termos geográficos e temporais, ao longo dos dias da semana e dos vários períodos de trabalho diário. A sua incidência é discriminada em função do tipo de obra (privada ou pública), da situação contratual e da idade dos trabalhadores vitimados. Em particular, distinguem-se as principais causas destes acidentes e as lesões que deles resultaram, de modo a permitir uma reflexão sobre as possíveis medidas a tomar com o objectivo de reduzir a sua ocorrência.

O presente trabalho refere algumas das consequências da falta de qualidade na utilização de estruturas provisórias de apoio à construção, tais como andaimes e cimbres por exemplo. Após uma breve descrição de instrumentos e metodologias da Garantia da Qualidade aplicáveis à indústria da construção, apresenta-se uma reflexão sobre a possível contribuição dos vários intervenientes na construção de estruturas provisórias, nas fases de concepção, fabrico, projecto, montagem e utilização, com o objectivo de diminuir as situações de risco actualmente associadas à sua utilização.

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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.

The project CircularBuild -

Relatório final do projeto PTDC/ECM/099121/2008

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.

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.

O presente relatório descreve a participação do LNEC no programa europeu de intercomparação de calibrações de forças

O presente trabalho apresenta um projecto de revisão da Norma Portuguesa NP 850 (1985)

O presente trabalho apresenta um projecto de revisão da Norma Portuguesa NP 386 (1965)

O presente trabalho apresenta um projecto de revisão das Normas Portuguesas NP 449 (1966)

O presente trabalho apresenta um projecto de revisão da Norma Portuguesa NP 450 (1966)

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.

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