Artigos de Revista

Abstract: Rigid block models are widely used in the analysis of masonrystructures, as they provide a sound and efficient approximation of the observedbehaviour, namely for modelling collapse modes that do not involve theinternal failure of the units. The options available for the numericalrepresentation of contact in rigid block models are discussed, in particular thewell-known point contact approaches. The accuracy of the various options iscompared for static and dynamical test problems involving bending of columnsand walls. Proposals are made concerning the level of contact discretisation,namely the number of contacts and weight rules, required for a good modelperformance.

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.

As temáticas associadas e associáveis à matéria geral dos quartos domésticos são muito amplas, sensíveis e significantes; desenvolve-se uma reflexão geral e informal sobre o tema, aproveitando para tratar o assunto num forte relacionamento entre o adequado desenvolvimento de quartos privados domésticos e de grandes quartos e pequenos apartamentos integráveis em edifícios com espaços e serviços comuns significativos.

This paper presents an experimental study about the durability of a cold curing structural epoxy (EP) adhesive exposed to different hygrothermal and outdoor ageing environments, typical of civil engineering applications, for up to two years: water and salt water immersion at 20 °C and 40 °C, continuous condensation at 40 °C, and outdoor ageing in a mild Mediterranean climate. After specific exposure periods, changes in the following physical properties and mechanical behaviour of the adhesive were assessed: (i) media diffusion, through water uptake (in hygrothermal environments); (ii) viscoelastic behaviour, through dynamic mechanical analyses (DMA); and (iii) flexural and (iv) in plane shear behaviour. Regarding media diffusion, water uptake did not follow a Fickian behaviour and a final saturation stage was not reached; two alternative non Fickian analytical models were successfully fitted to the test data and the corresponding diffusion parameters were determined. In what concerns the viscoelastic behaviour, while continuous condensation and outdoor ageing caused negligible changes, the Tg of the adhesive generally decreased due to immersion (around 20% in water and 10% in salt water after two years); in addition, at later stages of water immersion, the tan ? curve showed significant shape differences, with the usual curve peak being replaced by two different peaks; a generalised reduction of the storage modulus at the glassy plateau was also noted. In terms of mechanical performance, such plasticization effects were visible in the flexural and shear stress strain behaviours. The flexural properties exhibited irreversible degradation, with the highest reductions (two years of ageing in water at 40 °C) being about 24% and 30% in strength and modulus, respectively. Regarding the shear properties, in hygrothermal environments the shear modulus showed similar decreasing trends to the flexural modulus (43% reduction after one year), but the shear strength increased (~25%); the outdoor ageing affected the shear properties in the same way, but the magnitudes of the changes were lower.

Nesta comunicação, descrevem-se os ensaios em modelo físico realizados com o objetivo de caracterizar o campo de ondas em torno de um navio livre, quando sujeito a condições de agitação incidente regular e irregular. Estes dados são especialmente importantes para a validação de modelos numéricos de caracterização da resposta de navios à ação da agitação incidente. Assim, para cada condição de agitação incidente, efetuaram-se medições da elevação da superfície livre e das componentes da velocidade em diversos pontos em redor do navio. Apresentam-se as seguintes análises dos dados experimentais: análise temporal e espetral (espetro de energia e wavelets) dos valores de elevação da superfície livre e análise temporal da velocidade das partículas, a meio da coluna de água. A análise temporal e espetral de cada série de medições obtida permitem a caracterização da agitação nos pontos em redor do navio, em termos de alturas, períodos e velocidade. Avalia-se também a influência do navio nas características da agitação.

Aborda-se a natureza e o potencial funcional e vivencial dos espaços comuns em edifícios multifamiliares, uma matéria talvez ainda pouco conhecida/reconhecida e que tem a ver com o papel tão diversificado como protagonista destes espaços

As temáticas associadas e associáveis à matéria geral dos espaços domésticos privados e pessoais são extremamente amplas e tão sensíveis como significantes; portanto, não queremos correr o risco de dar a ideia de as irmos tratar, aqui, neste artigo, de forma exaustiva, iremos sim desenvolver uma reflexão geral e relativamente informal sobre o tema, aproveitando para organizar uma razoável estruturação desta matéria de modo a poder-se sustentar um avanço sobre o amplo leque tipológico em que os espaços domésticos privados e pessoai se podem e devem disseminar, tentando-se, ainda, apontar algumas reflexões e ideias como pistas para posteriores incursões teórico-práticas sobre a temática.

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