Papers

A ponte ferroviária de São João, sobre o rio Douro, na cidade do Porto, é uma estrutura de betão armado pré-esforçado, com uma extensão total de 1028,8 m. Projetada pelo Prof. Edgar Cardoso, esta obra de arte foi inaugurada em 1991.A ponte foi instrumentada durante a construção tendo em vista a caracterização experimental do seu comportamento estrutural estático, com base em campanhas periódicas. Em 2007 foi efetuada a modernização do sistema instalado, visando fundamentalmente a automatização das medições. Posteriormente foi instalado um sistema de monitorização de vibração contínua. Para a identificação de características dinâmicas da estrutura em tempo real, a partir das acelerações adquiridas, foi desenvolvido um procedimento automático, com base no método de identificação estocástica em subespaços usando as funções de correlação (SSI-COV) e a análise de clusters.Nesta comunicação é apresentada a metodologia desenvolvida e os resultados obtidos durante um ano e meio de monitorização.

Wave energy extraction in coastal regions may be an excellent alternative due to the increase in global demand for renewable energy. The viability study of this extraction depends on the evaluation of the wave energy potential that is higher in regions located in high latitudes. Therefore, this study shows evaluation and characterization of wave energy in the south of Brazil. Numerical simulations were carried out by the Mike 21 SW spectral model which was calibrated and validated in the region measurement campaigns. Annual, seasonal and monthly means and the temporal variability of the wave energy potential in a 10-year wave hindcast were analyzed offshore and nearshore. Annual mean fluxes in three points nearshore had similar values; the highest one was 6.7 kW/m, while the wave energy flux offshore was 22.3 kW/m. The refraction and the bottom friction dissipation were responsible for the wave attenuation from offshore to nearshore and, consequently, for the decrease in wave energy. The annual, seasonal and monthly variabilities of wave energy fluxes were moderate offshore and high nearshore. A directional analysis showed that the dominant wave directions were S and NE offshore whereas they were SSE and E nearshore.

The presence of dissolved oxygen (DO) in water flows is an important factor to ensure the aerobic conditions recognised as beneficial to preventing the occurrence of detrimental effects. The incorporation of DO in wastewater flowing in sewer systems is a process widely investigated in order to quantify the effect of continuous reaeration through the air-liquid interface or air entrained due to the presence of singularities such as drops or junctions. The location of sewer drops to enhance air entrainment and subsequently reaeration is an effective practice to promote aerobic conditions in sewers. In the present paper, vertical drops, backdrops and stepped drops were modelled using the computational fluid dynamics (CFD) code FLOW-3D® to evaluate the air-water flows due to the turbulence induced by the presence of these types of structures. An assessment of the hydraulic variables and an analysis of the air entrainment based on the available experimental studies were carried out. The results of the CFD models for these structures were validated using measurements of discharge, pressure head and water depth obtained in the corresponding physical models. A very good fit was obtained for the hydraulic behaviour. After validation of numerical models, analysis of the air entrainment was carried out.

The behaviour of natural and artificial slopes is controlled by their thermo-hydro-mechanical conditions and bysoil

A partir de uma pesquisa online exploratória, discutem-se alguns aspetos contemporâneos da patrimonialização da cultura azulejar. Aponta-se a institucionalização da rede na divulgação do património azulejar, a tendência para um incremento territorial e turístico na divulgação do azulejo integrado na arquitetura, bem como o extravasar do seu uso através do grafismo na arte urbana e na moda, mas também para o aumentar do efeito-denúncia online sobre a destruição do património azulejar. A pesquisa realizada permite ainda salientar alguns aspetos que interessam discutir no futuro desenvolvimento da pesquisa: a tendência para a atual assunção de que o património azulejar está também associado à transformação do azulejo em matérias e significados outros que não o revestimento na arquitetura; o atual papel do efeito online na divulgação do azulejo como matéria de património cuja manifestação assume variados e diferentes suportes; a divulgação transnacional do património azulejar, todavia, como uma manifestação da cultura nacional portuguesa; o quanto o efeito de transmutação do azulejo em outras matérias (tecido, móveis, sabonetes, …) pode, ainda que contraditoriamente, contribuir para divulgar e salvaguardar o património azulejar, mas também para uma espécie de efeito da sua desmaterialização; verificando-se que, num e noutro caso, as suas repercussões online são de assinalar. Menciona-se o potencial da pesquisa online no campo do património e, por fim, debate-se algumas das suas limitações, nomeadamente por não colocar o pesquisador próximo dos territórios sociais de património.

No presente trabalho descreve-se a aplicação de uma metodologia para avaliação das consequências do galgamento no porto de Ponta Delgada, S. Miguel, Açores, recorrendo a uma análise multicritério (Processo de Análise Hierárquica, AHP) do impacto da ocorrência de galgamentos superiores aos limites admissíveis. Esta metodologia permite obter resultados baseados numa análise espacial dos indicadores que caraterizam a zona portuária em estudo, no que diz respeito à sua importância relativa.

Prototype boards of high-density expanded cork agglomerates (230 and 290 kgm

Ventilation systems are absolutely necessary to ensure adequate levels of indoor air renewal. In Portugal,multifamily buildings use natural, mechanical or mixed ventilation systems. However, when using naturalventilation, we can hardly know the correspondence between the ventilation system installed andthe ventilation rate achieved with the same system, due to its strong dependence on wind. In this article,through simulation with software CONTAM, and based on experimental data of air permeability of thebuilding envelope and on the performance characteristics of ventilation devices, we carry out a sensitivityanalysis by varying some of the most significant parameters in mixed ventilation systems. Theseparameters are as follows: pressure loss of air inlets, air permeability of window frames, air extractionflows in the kitchen and positioning of interior doors, either closed or open. The annual simulation ofair flows takes into account the factors as follows: environmental conditions representative of the Portuguesecontinental climate (four cities); subdivision for heating and cooling climatic seasons; and theproduction of indoor pollutants (CO2 and water vapor). The most significant conclusions to be drawnfrom the simulations are the following: the low air permeability of the envelope leads to reductions in airchange rates close to the limit set by the Portuguese regulations; the continuous mechanical ventilationin the kitchen, the installation of an air inlet in the kitchen (opening at the maximum air flow), as wellas closing the doors of service compartments (kitchen and bathrooms) significantly reduce the levels ofpollutants.

Several concrete structures show signs of deterioration resulting from internal chemical reactions, such as the alkali-silica reaction (ASR). It is well known that these swelling reactions occur in the presence of moisture, between some silica mineral phases present in the aggregates and the alkalis of the concrete, leading to the degradation of concrete structures and consequently compromising their safety. In most of the cases, rehabilitation, demolition or even rebuilding of such structures is needed and the effective costs can be very high. Volcanic rocks are commonly used as aggregates in concrete, and they are sometimes the only option due to the unavailability of other rock types. These rocks may contain different forms of silica that are deleterious to concrete, such as opal, chalcedony, cristobalite, tridymite and micro- to cryptocrystalline quartz, as well as Si-rich volcanic glass. Volcanic rocks are typically very finegrained and their constituting minerals are usually not distinguished under optical microscopy, thus leading to using complementary methods. The objective of this research is to find the more adequate analytical methods to identify silica phases that might be present in volcanic aggregates and cause ASR. The complementary methods used include X-Ray Diffraction (XRD), mineral acid digestion and Scanning Electron Microscopy with Energy Dispersive X-Ray Spectrometry (SEM/EDS), as well as Electron Probe Micro-Analysis (EPMA).