Artigos de Revista

Discute-se o interesse que a diversidade sociocultural, económica e funcional pode ter na promoção da revitalização e salvaguarda dos centros históricos. A título de exemplo, debate-se sobre determinadas características da organização e uso socioespacial da Baixa, em Lisboa, procurando realçar o potencial interesse de uma intervenção que promova uma ocupação social, cultural, económica e funcional diversificada.

This paper extends the previous R&D project on the evaluation of intermodal freight transport scenarios (seamless multimodal logistic chains) centered in the Port of Sines in Portugal where a set of alternative investment options were compared: (i) maritime

Electric bikes (e-bikes) may help in transport decarbonisation in European cities. To fully assess the market potential of e-bikes, further research is needed to understand users

Circulation patterns and physical regimes play a major role in estuarine ecosystems.Understanding how different drivers, like climate change, may affect the estuarine dynamics is thusfundamental to guarantee the preservation of the ecological and economical values of these areas.The Tagus estuary (Portugal) supports diverse uses and activities, some of which may benegatively affected by changes in the hydrodynamics and salinity dynamics. Numerical modelshave been widely used in this estuary to support its management. However, a detailedunderstanding of the three-dimensional estuarine circulation is still needed. In this study, athree-dimensional hydrodynamic baroclinic model was implemented and assessed using themodeling system SCHISM. The model assessment was performed for contrasting conditions inorder to evaluate the robustness of the parametrization. Results show the ability of the model torepresent the main salinity and water temperature patterns in the Tagus estuary, including thehorizontal and vertical gradients under different environmental conditions and, in particular, riverdischarges. The model setup, in particular the vertical grid resolution and the advection scheme,affects the model ability to reproduce the vertical stratification. The TVD numerical scheme offersthe best representation of the stratification under high river discharges. A classification of theTagus estuary based on the Venice system regarding the salinity distribution for extreme riverdischarges indicates a significant upstream progression of the salt water during drought periods,which may affect some of the activities in the upper estuary (e.g., agriculture). The modeldeveloped herein will be used in further studies on the effects of climate change on the physicaland ecological dynamics of the Tagus estuary.

This paper deals with flow field and sediment flux measurements at alpine desanding facilities. 3D flowvelocities and turbidity were recorded and water samples were taken at three alpine desandingfacilities. The samples were evaluated regarding suspended sediment concentration (SSC) andparticle size distribution (PSD) in the laboratory. SSC was correlated with turbidity and reliablecorrelations were found for two facilities. The applied instrumentation and methods proved to beappropriate to assess flow field and sediment fluxes. The results show that the flow field isinhomogeneous in large parts of the basins and that the presence of tranquilizing racks has astrong influence on the flow. PSD revealed a refinement of the mean particle size in streamwisedirection. The mass-related trapping efficiency of the desanding facilities was estimated based oncalculated sediment fluxes and compared to two different trapping efficiency definitions. Theresults are briefly compared with a current design guideline.

Several concrete structures had shown signs of degradation some years after construction due to internal expansive reactions. Among these reactions there are the alkaliaggregate reactions (AAR) that occur between the aggregates and the concrete interstitial fluids which can be divided in two types: the alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR). The more common is the ASR which occurs when certain types of reactive silica are present in the aggregates. In consequence, an expansive alkali-silica gel is formed leading to the concrete cracking and degradation. Granites are rocks composed essentially of quartz, micas and feldspars, the latter being the minerals which contain more alkalis in their structure and thus, able to release them in conditions of high alkalinity. Although these aggregates are of slow reaction, some structures where they were applied show evidence of deterioration due to ASR some years or decades after the construction. In the present work, the possible contribution of granitic aggregates to the interstitial fluids of concrete by alkalis release was studied by performing chemical attack with NaOH and KOH solutions. Due to the heterogeneity of the quarries in what concerns the degree of alteration and/or fracturing, rock samples with different alteration were analysed. The alteration degree was characterized both under optical microscope and image analysis and compared with the results obtained from the chemical tests. It was concluded that natural alteration reduces dramatically the releasable alkalis available in the rocks.

Abstract. Seismic testing and analysis using large infrastructures, such as shaking tables and reaction walls, is performed worldwide requiring the use of complex instrumentation systems. To assure the accuracy of these systems, conformity assessment is needed to verify the compliance with standards and applications, and the Quality Management Systems (QMS) is being increasingly applied to domains where risk analysis is critical as a way to provide a formal recognition. This paper describes an approach to the assessment of the metrological performance of seismic shake tables as part of a QMS recognition, with the analysis of a case study of LNEC Seismic shake table.

Pese embora o esforço realizado nos últimos anos, a nível internacional e nacional, para a melhoria do comportamento do betão e na prevenção da sua degradação, continua-se a assistir ainda ao aparecimento dum número elevado de estruturas de betão com problemas de durabilidade, essencialmente os relacionados com causas químicas, como são exemplo as reações expansivas internas e a corrosão das armaduras. Neste contexto, o correto diagnóstico da(s) forma(s) de degradação presentes numa determinada estrutura de betão ganha uma especial importância, quer em termos do prognóstico e modelação da evolução futura desses mecanismos de degradação, como no apoio à a priorização das intervenções de manutenção e de reparação a implementar. Neste artigo após uma contextualização dos tipos de degradação do betão relacionados com as reações expansivas internas e a corrosão das armaduras, são apresentadas as principais técnicas de ensaio usadas para o seu diagnóstico, com a exemplificação da sua aplicação a casos concretos, realçando-se os cuidados a ter na interpretação dos resultados.

Neste artigo apresentam-se os resultados da avaliação dos efeitos que mais contribuem paraa deformação sofrida por tubagem plástica enterrada, recorrendo a simulação complaneamento de experiências (DOE). Os resultados obtidos estão de acordo com os que seobtêm pela aplicação de outros métodos estatísticos de análise, tais como o método doscomponentes principais e de análise de fatores, e são consistentes com os resultados deensaios no terreno, confirmando-se também assim a eficácia e adequação destes métodospara avaliações prévias, com grande economia de recursos.