Papers

Em primeiro lugar importa registar que se considera que o jogo das relações entre rua e casa e entre exterior e interior é, mais do muitos outros aspectos que podem (e devem) ser tomados em conta no que se refere à matéria urbanística, o verdadeiro ligante de uma intervenção urbana e de habitar consistente em termos de presente e futuro e em termos de interesses humanos e sociais. E desde logo se pode apontar que o principal objectivo é criar e melhorar tais relações qualificando-as como verdadeiros “percursos íntimos, coesos e ricos entre (cidade) «rua» e «casa»”. Será esta urbanidade, concebida a partir de uma concepção global e da interpenetração das funções o objectivo da defendida e re-interpretada Arquitectura Urbana, feita das tais múltiplas e estimulantes relações, que deverão estar sempre claramente ao serviço do homem habitante e privilegiando, designadamente, os grupos mais sensíveis, como as crianças e os idosos, até porque quando se faz uma cidade que é, assim, estruturalmente, mais amigável, se faz, também, uma cidade mais cívica, culta e rica em termos de conteúdos.

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As anomalias que se podem verificar em coberturas de edifícios, algumas das quais são a causa das recorrentes infiltrações de água pelo teto do último piso, levam potenciais compradores ou inquilinos, especialmente os mais informados tecnicamente, a evitar a aquisição ou arrendamento de apartamentos ou espaços do último piso. E quando a cobertura é em terraço, maior é a sensação de que tais infiltrações serão inevitáveis. Assim, registam-se e comentam-se dois casos típicos de anomalias em coberturas em terraço em Portugal, das dezenas que poderiam ser enumeradas e que vêm mencionadas na bibliografia da especialidade.

Due to the improvement of several properties, such as lower water absorption and increasing resistance to microcracking, polymer modification of mortar and concrete potentially leads to an inhibiting effect on alkali– silica reaction (ASR). In this study, polymer–cement mortars (PCMs) were subjected to accelerated alkali reactivity tests and their performance compared to that of an unmodified cement mortar (CM). Expansion of PCMs was overall higher, but SEM observations revealed apparent lower microcracking intensity of the cement paste, compared to the unmodified CM. Subsequent stiffness damage tests (SDTs) quantified the existing damage after alkali reactivity tests and confirmed the lower microcracking intensity in PCMs.

At the National Laboratory of Civil Engineering (LNEC), Portugal, and with financial support from Fundação para a Ciência e a Tecnologia (FCT) given to the research project PTDC/ECM/101810/2008 – Polymer-modified Cement Mortars for the Repair of Concrete Structures, an ongoing study aims to assess the possible prevention of steel corrosion induced by carbonation in PCMs and to set new research topics based on the results, due to the potential effect of polymers on the properties of cement mortar that have been shown to influence the corrosion of embedded steel, such as the reduction of water absorption and ionic mobility and the increase in electrical resistivity and resistance to CO2 uptake. The action of styrene-butadiene and acrylic-styrene polymers on steel corrosion in cement mortars was assessed after steel depassivation was induced by carbonation in an environment meeting the required conditions for progression of steel corrosion.

Irrigation canals are primary hydraulic infrastructures from an agricultural point of view and their performance is highly dependent on the efficiency and durability of their coatings. This paper presents the main conclusions of a survey undertaken in Portugal which concluded that in most situations the following technologies are used: concrete cast on site; precast concrete slabs; prefabricated membranes (polymer bitumen or synthetic). These linings may manifest various pathologies with significant consequences on the amount of water lost due to lack of watertightness. These defects are classified by lining solution and their main causes identified. Finally, an exhaustive set of recommendations and rehabilitation techniques are described in order to minimize water leakage from the canals.

The aim of this paper is to compare sorting and ranking methods for prioritization of rehabilitation interventions of sewers, taking into account risk, performance and cost. For that purpose multiple criteria decision-aid (MCDA) methods such as ELECTRE TRI for sorting and ELECTRE III for ranking are applied in a real case-study and the results obtained are compared. The case study is a small sanitary sewer system from a Portuguese utility located in the metropolitan area of Lisbon. The problem to investigate is the prioritization of the sewer candidates for rehabilitation. The decision maker (a panel group of specialists) has chosen five assessment measures: water level and maximum flow velocity (hydraulic performance indices), sewer importance and failure repair cost (collapse-related consequences of failure) and the risk of collapse. The results show that the outcomes from ELECTRE III are easier to understand than those from ELECTRE TRI method. Two different sets of weights were used, and the sorting and ranking results from both methods were found to be sensitive to them. ELECTRE TRI method is not straightforward as it involves technical parameters that are difficult to define, such as reference profiles and cut levels.

The economical and ecological importance of tidal inlets has fostered the development of empirical tools for inlet management during the last century. This study aims at confronting these empirical theories with results obtained with a process-based numerical model, MORSYS2D. This 2DH morphodynamic modeling system is applied to an idealized tidal inlet/lagoon system with different combinations of significant wave height, tidal range and tidal prism. The numerical model predictions are compared to the empirical models of Hayes, Bruun, O'Brien and FitzGerald and to morphologies observed at natural tidal inlets. The results present good accordance with observations as well as with some key behaviors predicted with the empirical theories. The predicted morphologies satisfy the relation of O'Brien between the tidal prism and the cross-sectional area, the model reproduces the conceptual model of sand by-passing by ebb-tidal delta breaching of FitzGerald and the classifications of Hayes and Bruun are generally respected. However, some inconsistencies between model results andHayes classification highlight the limitations of applying this classification,which only considers the yearly-averaged significant wave height and tidal range, to a single tidal inlet case.

A experiência mostra (e a ciência explica) que as estruturas de madeira podem apresentar muito boa resistência ao fogo, especialmente no caso de elementos com grandes secções transversais. Isto resulta de a temperatura no interior de grandes secções de madeira se manter praticamente inalterada, sob proteção de uma camada exterior carbonizada, que progride de forma mais ou menos constante e relativamente lenta para o interior, a partir das superfícies expostas ao fogo.No entanto, algumas estruturas antigas são constituídas por elementos de secções relativamente modestas e por vezes apresentam degradações superficiais e interiores, mais ou menos significativas. Há ainda que ter em conta que certos pormenores construtivos, designadamente envolvendo as ligações, e o estado da superfície da madeira podem afetar o seu desempenho. Igualmente a geometria do edifício, o tipo de utilização e a presença de equipamentos ou produtos armazenados podem aumentar o risco ou a intensidade do incêncio, reforçando a necessidade de adotar medidas de proteção específicas.

Bridge falsework systems are frequently used in the construction, rehabilitation and retrofit works of bridge structures. These structures have a significant impact on the cost, construction rate and construction safety of the supported permanent structures. However, the relevant stakeholders often do not consider them as important as permanent structures, and in recent years, a high number of accidents involving bridge falsework systems have been reported.A research programme was initiated aiming to contribute to a better knowledge about the structural behaviour, reliability and robustness of bridge falsework systems. In this paper, the advances and existing challenges in the design of bridge falsework systems will be summarised. Additionally, the basis of a framework for the structural design of these structures within the context of a risk-informed decision-making is presented.