Artigos de Revista

Evaluation of the sliding stability of concrete dams requires the use of numerical tools not only able to simulate the coupled hydromechanical behavior but also able to adequately represent the foundation discontinuities and the specific features of dam foundations. The formulation of a threedimensional (3D) small displacement finite element model based on interface elements to simulate the discontinuities is presented. In this model, the hydraulic behavior is simulated assuming that the water flow occurs only along channels located at the edges of the triangular interface elements that simulate the discontinuities. The model is used to perform coupled hydromechanical analysis of a large arch-gravity dam and to assess safety against dam base sliding, assuming different constitutive models at the dam/foundation interface and two different approaches: (i) strength reduction method and (ii) amplification of the hydrostatic pressure, assuming an increase in the reservoir level. The present study shows that consistent results are obtained with the proposed numerical model and that stability analysis should preferably be carried out using the method of increasing the hydrostatic pressure and the corresponding uplift pressures, as this methodology leads to significantly lower safety factors.

No presente texto desenvolve-se, em primeiro lugar, uma reflexão genérica sobre as necessidades habitacionais mais específicas dos idosos, passando-se, depois, para uma reflexão sobre a importância de uma informada e ativa capacidade de escolha e de participação no apuramento de uma habitação adequada aos idosos; afinal há, já qui, uma perspetiva que avança numa importância tendencialmente

The purpose of this Special Issue was to collect and publish technical and research papers, including review papers, focusing on the recycling of road pavement materials to promote pavement sustainability performance. Ten papers were published in total covering the use of construction and demolition waste (reclaimed asphalt pavement, recycled concrete aggregate and glass) and industrial waste (plastic and slag). The application of recycled materials concerns bituminous mixtures, concrete mixtures, and non-traditional interlocking blocks or cobbles. The most relevant contributions of each paper are briefly described in the following sections. The papers involved thirty-four authors from eleven countries of Europe (Belgium, Finland, Italy, the Netherlands, and Portugal), Africa (Nigeria), Asia (Malaysia and Saudi Arabia), Australia, and South America (Brazil and Colombia).

Performance assessment is recognized as an important management tool for urban water systems. This article describes the application of a performance assessment framework for storm water systems, in collaboration with two Portuguese urban water utilities. A performance assessment system was built for each water utility, including objectives, assessment criteria and performance metrics. The results showed the existence of areas vulnerable to flooding occurrences and the need for investment in rehabilitation. The application of the performance assessment framework supports the identification of systems’ vulnerabilities and priorities for intervention. Opportunities and suggestions for improving data collection procedures are identified.

The present project addresses a problem related to the erosion effects on a breakwater barrier due to waves which leads to its degradation and that may eventually lead to lack of functionality of the structure. In the present case, the breakwater acts as a physical barrier between the Atlantic Ocean and the cargo Harbour of Leixäes, in Matosinhos, Portugal, justifying the needs of health monitoring of the barrier.To monitor this structure, with a length of roughly 700 m, the need of a fast data acquisition system led to the choice of imaging techniques which allow for a fast acquisition of a diversified data set. The images were acquired using a high-resolution camera attached to an unmanned aerial vehicle (UAV), enabling a faster and more automated procedure that leads to the systematization of the process, while being compatible with the difficult accessibility of the structure, which is surrounded by sea waves. Point clouds corresponding to the breakwater

Storms impacting sandy coastal areas produce hazard such as erosion as overwash, in turn, promote risk to life and property damage in occupied areas.

A tunnel fire is a dangerous accident, which may lead to serious injuries and deaths. This work studies the flow of combustion products during naturally ventilated tunnel fires, i.e., without a mechanical ventilation system. In such an event, two stratified layers with opposing velocity directions are formed. The safety of tunnel users is compromised if the smoke, initially flowing in the upper layer, contaminates the lower one, which has been found to happen abruptly at a distance xc from the fire. This is caused by the cooling of the jet leading to a large enough decrease in momentum for the smoke to be entrained by the lower layer. Natural ventilation may be an effective and inexpensive smoke control strategy if the fire-to-portal distance is shorter than xc. However, there is a lack of research to predict under which conditions this occurs and how xc is influenced by factors such as natural wind. An open-source Computational Fluid Dynamics (CFD) code, fireFoam, was used to conduct Large Eddy Simulations (LES) of naturally ventilated tunnel fires. The numerical model was validated by performing a simulation of a large-scale tunnel fire test. Additionally, 7 fire scenarios with varying wind velocities were simulated. The contamination distance xc was found to decrease for higher wind velocities. Furthermore, a simple semi-analytical model was employed to obtain quick estimates of xc, by calculating ceiling jet properties using balance equations and empirical correlations. Model coefficients were calculated using the CFD results.

Performance assessment is essential for effectively managing drinking water systems. It allows to understand the system's behaviour, identify critical components and subsystems, and help with the decision analysis of measures to improve economic, infrastructural and water and energy resources. The current paper proposes an updated methodology for diagnosing drinking water networks, considering different perspectives: water and energy efficiency, infrastructural sustainability, and the quality of service provided, including resilience and redundancy concepts. Several performance indicators and indexes, including Resilience index and Entropy, are recommended to describe each perspective. The methodology is applied to a real-life network, and the attained results are discussed. The status quo situation for the network area is assessed, and the main problems are identified (i.e., high friction losses, inefficient pump operation, old pump equipment). Different improvement solutions are considered (e.g., pipe replacement with higher diameter, pump operation improvement, pump replacement). These interventions are considered individually or combined. Using the resilience-based perspective with other performance assessment criteria has provided a broader assessment. The resilience index has proven sensitive to the different alternatives, endorsing the system's efficiency. Smaller values of the resilience index indicate that a small amount of energy in excess is available as surplus energy in the consumption nodes, being dissipated, either as pumping inefficiencies, water losses, or friction and singular head losses. The Entropy metric is sensitive to the network layout and is helpful in alternatives that consider flow path alterations to prevent the impact of pipe failure. The best improvement alternative achieves a considerable enhancement in energy efficiency, maintains a good quality of service, improves the system's infrastructural sustainability, and corresponds to the highest resilience index value.

Among thermal insulation solutions for historic walls, thermal renders and plasters appear to be a very feasible option. Thus, this work analyses commercially available thermal mortars suitable for the scope.An extensive experimental campaign showed that testing single materials only, which is the standard requirement for thermal mortar-based systems, is in fact not sufficient for understanding the potential impact of the intervention on walls: whole-systems should also be examined. This study provides a detailed characterization of materials and systems, useful as a database for forthcoming investigations on compatibility and efficacy for application on historic walls, via numerical hygrothermal simulations.

A complexidade do sistema via-férrea, em termos da variabilidade do comportamento estrutural e material ao longo de seu ciclo de vida, tem-se constituído um obstáculo para o estabelecimento de métodos robustos de previsão do seu comportamento de longo-prazo. Neste trabalho apresenta-se uma implementação computacional que incorpora algumas funcionalidades para uma reprodução mais realista desse comportamento, face a outras existentes. Para demonstrar as potencialidades desta ferramenta, são analisados cenários de plena via, tendo-se introduzido, em alguns deles, uma travessa sem apoio na camada de balastro (“travessa suspensa”), de forma a analisar o impacto dessa anomalia no desempenho da via sob a aplicação de milhões de ciclos de carga, relativos a diferentes veículos. Esta abordagem permitiu avaliar a interdependência entre efeitos dinâmicos, como a interação roda-carril, e efeitos de longo prazo, como a evolução das trajetórias de tensões no interior da camada de balastro, evidenciando um ciclo retroalimentado entre esses dois processos.