Artigos de Revista

The use of adhesives to produce assembled structural joints in the building industry is increasing, particularlyin the context of on-site rehabilitation of timber structures. On their own or together with steel orfibre reinforced polymer composite connecting materials, adhesives can provide low intrusive, fast, versatileand effective on-site repair or reinforcement interventions to timber structures. Most common applicationsinvolve sealing and repair of cracks, drying fissures and delamination of glued laminated members; replacementof decayed beam ends; strengthening of timber members; and repair and strengthening of mechanicaltimber joints. The performance of bonded joints highly depends on their design and detailing, surfacespreparation, selection and application of adhesives, and full compliance with their cure schedule. Therefore,the work should be carried out by well-informed, trained and certified operators following a QualityAssurance Program to ensure satisfactory end-product strength and durability.Despite some recent developments, the exploitation of the full potential for on-site bonded joints is mainlyrestrained at present by the lack of structural design guidance, standards for durability assessment and onsiteacceptance testing.This article discusses briefly the use of adhesives on the construction site in the context of structural repairand reinforcement; the requirements and practical difficulties in the work on site with regards to the strengthand durability of the rehabilitated timber structure; and the consequent need for quality control. It alsohighlights the characteristics and requirements that must be fulfilled by structural adhesives and reinforcingmaterials; factors affecting performance and durability of bonded joints; and ways to improve adhesion anddurability. Finally, it points out some research needs and future developments identified by the authors.

Abstract. Many historical buildings with renders based in air lime still exist in Portugal. These old mortars have proved to be durable and reliable materials. However, new lime mortars prepared nowadays to be used in conservation practice, often present low strength in comparison with cement mortars.This paper presents a study of the viability of improving the performance of lime mortars througth the use of different nature aggregates (Tagus river siliceous sand and crushed calcareous sand) as well as different size distributions, varying the filler contents. For that purpose a set of mortars with volumetric proportion of 1:3 (lime:aggregate), using silicious sand from Tagus river or calcareous sand and including different volume percentages of aggregate replacement by filler (0% of incorporation, 5% of incorporation, 10% of incorporation), were prepared. An evaluation of the main characteristics of this set of mortars was made in terms of: i) hygric behaviour (water absorption by capillarity), and ii) mechanical resistance (flexural and compressive strength and elastic modulus). This study aims to assess the viability and possible advantages of using calcareous aggregate in lime mortars and to evaluate the possibility of improving characteristics through a better compaction obtained by the incorporation of different ratios of filler.

As áreas mineiras degradadas (AMD) são locais ambientalmente problemáticos que exigem, na maioria das vezes, estudos de caracterização complexos. O recurso a métodos expeditos, que permitem obter dados fiáveis e a baixo custo, numa fase precoce desses estudos, facilitam a gestão das tarefas subsequentes. É o caso dos analisadores portáteis de fluorescência de raios-X (APFRX), que permitem determinar semi-quantitativamente a concentração em metais pesados e metalóides em solos e resíduos mineiros, in situ e ex situ. A qualidade dos dados obtidos in situ e ex situ foi demonstrada em trabalhos anteriores. Na presente comunicação apresentam-se os trabalhos desenvolvidos na área mineira de Santo António, em que se obteve um zonamento da contaminação área, facilitando-se o diagnóstico preliminar do respectivo estado de degradação e a optimização de um programa de amostragem específico.

A simple analytical formulation that reproduces a skewed, nonlinear near-bed wave orbital velocity is presented. It contains four free parameters, where two are solely related to the velocity and accelerationskewnesses. The equation is compared with other models and is validated against field and laboratoryexperiments. The results reveal that it can simulate a wide range of nonlinear wave shapes, reproducing satisfactorily the measured nonlinear wave particle velocity. Also, the new expression overcomes somelimitations of the other models. The new formulation is therefore capable of being used in many engineering applications that require the use of representative wave forms.

RESUMONuma construção pré-esforçada a armadura é uma componente da ancoragem dominante na segurança dos elementos suportados. A armadura pode ser de vários tipos. No mercado existem diversas tecnologias e sistemas, pelo que a armadura deve ser seleccionada em conformidade com as cargas e com o disposto pelos documentos regulamentares e normativos. A sua durabilidade reveste-se de importância vital na longevidade da obra, sendo necessária protecção contra a corrosão. O comportamento do aço de pré-esforço relativamente à corrosão depende: da qualidade das caldas de injecção; do grau de preenchimento das bainhas; do recobrimento da armadura e das cabeças. A função das ancoragens e o tempo de vida da estrutura ancorada têm uma implicação directa na tecnologia a implementar. Construída a ancoragem, verifica-se o seu comportamento mecânico com ensaios de carga, para avaliar e verificar se as exigências de projecto são respeitadas.

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Three models were applied to analyse the planform of bay-shaped Portuguese beaches. They are based on empirical mathematical functions: the logarithmic spiral bay equation, the hyperbolic tangent bay equation, and the parabolic bay equation. These models were applied to analyse the fitting to the beach planform of 42 beaches on the Portuguese Atlantic coast which was calculated through the validation against the waterline extracted from rectified aerial photographs. The logarithmic spiral model fits well the curved zone of the beaches, in particular small beaches with two headlands. Despite the good fitting of the hyperbolic tangent model for one headland beach, its process of approximation to the solution was less intuitive than the processes of the other two models, therefore its application was more exhaustive. A comparative analysis between the logarithmic spiral model and the hyperbolic tangent model revealed the best fit of the first. The application of the parabolic model allowed to conclude that despite the majority of the beaches analysed being in dynamic equilibrium condition due to the high energy wave regime of the Portuguese Atlantic coast, their planform was very close to the planform in static equilibrium condition due to the high dynamics of the coastal environment

Ao longo da sua história, a cidade de Lisboa tem sofrido os efeitos devastadores de diversos sismos que foram responsáveis por danos e perdas relevantes no seu parque edificado e seus habitantes. Os objectivos do presente artigo englobam a identificação, a análise e a avaliação do risco sísmico deste concelho, cumprindo-se, desta forma, algumas das etapas do processo de gestão do risco. Efectuou-se a análise de risco para uma perigosidade sísmica regida por mais do que um cenário probabilístico de ocorrência de sismos. Para o efeito, caracterizou-se a perigosidade sísmica das 53 freguesias de Lisboa, considerando dois cenários de ocorrência construídos sobre os mesmos pressupostos em que se fundamentou a acção sísmica que serviu de base ao Anexo Nacional do Eurocódigo 8. Avaliou-se ainda a exposição do parque habitacional e habitantes deste concelho, classificou-se e caracterizou-se a vulnerabilidade sísmica dos elementos expostos, traçaram-se as curvas de risco sísmico para a cidade de Lisboa e estimaram-se os valores esperados anuais das perdas económicas e sociais nas freguesias desta cidade. Da análise efectuada ressalta que as perdas totais são condicionadas essencialmente pelo cenário de acção sísmica próximo, que as freguesias mais antigas são aquelas em que o risco relativo esperado anual é mais elevado e que as freguesias responsáveis pelos maiores valores de risco absoluto são as que apresentam a vulnerabilidade sísmica mais elevada e os maiores valores de exposição.A apreciação do risco sísmico efectuada para Lisboa permite concluir que o risco de morte anual devido a sismos a que os habitantes desta cidade estão expostos se situa na zona ALARP (As Low As Reasonably Practicable).

This paper investigates the powdered activated carbon (PAC) contribution to the fouling control by natural organic matter (NOM) in PAC/UF hybrid process, as well as the foulant behaviour of the PAC itself. Solutions of NOM surrogates (humic acids, AHA, and tannic acid, TA) and AOM/EOM (algogenic organic matter/extracellular organic matter) fractions from a Microcystis aeruginosa culture were permeated through an ultrafiltration (UF) hollowfibre cellulose acetate membrane (100 kDa cut-off). The greatest impairment on flux and the poorest rejection were associated with polysaccharide-like EOM substances combined with mono and multivalent ions. PAC, either in the absence or in the presence of NOM, did not affect the permeate flux nor the reversible membrane fouling, regardless of the NOM characteristics (hydrophobicity and protein content) and water inorganics. However, PAC controlled the irreversible membrane fouling, minimising the chemical cleaning frequency. Furthermore, PAC enhanced AHA and TA rejections and the overall removal of AOM, although it was apparently ineffective for the highly hydrophilic EOM compounds.

This paper investigates the powdered actuivated carbon (PAC) contribution to the fouling control by natural organic maitter (NON) in PAC/UF hybrid process, as well as the foulant behaviour of the PAC itself. Solutions of NOM surrogates (humic acids, AHA, and tannic acid, TA) and AOM/EOM (algogenic organic matter/extracellular organic matter) fractions from a Microcystis aeruginosa culture were permeated through an ultra