Artigos de Revista

The analysis and control of deformability of wall coating mortars contributes to minimize crack development and propagation, one of the most common anomalies in building facades. Many of these cracks appear due to internal stresses in the coating mortar, because of imposed deformations or of imposed restrictions by the substrate. These deformability studies should include one or more experimental methods to determine the modulus of elasticity (E) of the coating mortars in question. There are two approaches to experimentally determine E for mortar specimens: static and dynamic experimental methodologies. For civil engineering applications, the results obtained from static methodologies are more adequate than those obtained with dynamic methodologies. However, since static E results are scarce due to a lack of an established static methodology for mortars, mainly due to their lower mechanical resistance, friable behaviour and higher frailty when compared to concrete, engineers are led to use the established dynamic methodologies. This paper proposes an experimental methodology to determine the static E for moulded mortars specimens. The methodology was adapted from the standard procedure used for concrete specimens, to accommodate the specific characteristics of mortar specimens, namely: provide reliable displacement and applied load data; solve issue related to specific mechanical characteristics of mortar specimens, such as low strength and friable behaviour. This methodology was applied to standard moulded mortar specimens made from multiple mineral binders (cement, hydraulic lime and air lime). In order to validate it, the obtained results were compared with two, well-established, dynamic experimental methodologies (Resonance Frequency and Ultrasonic methodologies) as well as with reference values from relevant bibliography. Using the previous data, this paper also includes a preliminary analysis on the ratios between static and dynamic E values for the studied mortars, representing another objective of this study.

The most studied device used for extracting wave energy is the Oscillating Water Column (OWC). In general, numerical simulations of these cases by means of models based on Reynolds Averaged Navier-Stokes equations adopt the Volume of Fluid method to deal with the free surface flow which is considered incompressible in both water and air. The aim of this study is to investigate the influence of the compressibility effect on the air inside the OWC chamber by the FLUENT® numerical model. A methodology is implemented, taking into account both water and air flows incompressible, but, at every instant, a pressure condition is imposed on the top boundary of the chamber to consider the compressibility effect. This pressure condition is based on an analytical equation that considers the isentropic transformation of the air and effects of Wells and impulse turbines. Results of compressible and incompressible numerical models are compared. The amplification factor, the root mean square of air pressure inside the chamber and OWC efficiency in relation to incident wave period, wave height and turbine characteristic relation are analyzed. Results show that air compressibility effects can diminish the predicted OWC efficiency up to about 20% in both Wells and impulse turbines.

In this study, a numerical analysis of the performance of two Oscillating Water Column (OWC) wave energy converters, at different front and back wall slopes, was carried out. The first device had vertical front and back walls and the second one had its wall slopes of 40° in relation to the horizontal plane. The FLUENT® numerical model, which is based on the Reynolds-Averaged Navier-Stokes (RANS) equations, was used. The Volume of Fluid (VoF) method was employed to take into account free surface flows. The case study comprised a 10 m deep flume with an onshore OWC at its end, equipped with a Wells turbine. A 2D hydrodynamic mathematical model was employed and a 3D air pressure effect inside the OWC air-chamber was considered. Analyses of the hydrodynamics behavior, fluid-structure interaction outside (run-up/down, reflected waves) and inside the chamber (free surface elevation, sloshing) and energy distribution (pneumatic extracted energy, reflected wave energy and energy losses) were conducted. Results showed that the device with inclined walls had the best efficiency in comparison with the other one. However, the latter showed lower variation in efficiency in the wave period range than the former.

This paper addresses the planar measurement problem in the destructive mechanical testing of masonry specimens, describing the proposed optical measurement solution. The adopted affine geometrical camera model is described as well as its experimental implementation using a digital camera and a measurement referential traceable to the International System of Units (SI). Experimental results from non-destructive tests are presented and discussed, including measurements obtained from the use of classical contact instrumentation. Measurement estimates and uncertainties related to the quantified mechanical properties are also shown.

Water systems and particularly wastewater treatment may only improve or keep high-quality service if their performance is continuously measured and benchmarked against peers. This paper presents a casestudy developed under the Portuguese Initiative on Water Quality, Treatment and Energy (iEQTAWWTP), involving 7 water utilities, and focused on the performance assessment of 23 urban wastewater treatment plants (WWTPs) covering a wide range of treatment sequences and capacities (700-54000 m3/ d). An earlier developed system of key performance indicators (KPIs) with reference values was used to assess the plants’ overall performance for effectiveness and reliability, sludge production and energy efficiency taking into consideration, whenever adequate, treatment technology, treated wastewater volume and influent characteristics. This application proved the soundness of the KPI system and its reference values for a blind comparison among WWTPs but also for treatment type- and capacity-specific clustering, ultimately supporting water utilities in a continuous practice of WWTP performance improvement.

Urban areas are dynamic, facing evolving hazards, having interacting strategic services and assets. Their management involves multiple stakeholders bringing additional complexity. Potential impacts of climate dynamics may aggravate current conditions and the appearance of new hazards. These challenges require an integrated and forward-looking approach to resilient and sustainable urban development, being essential to identify the real needs for its achievement. Several frameworks for assessing resilience have been developed in different fields. However, considering the focus on climate change and urban services, specific needs were identified, particularly in assessing strategic urban sectors and their interactions with others and with the wider urban system. A resilience assessment framework was developed directing and facilitating an objective-driven resilience diagnosis of urban cities and services. This supports the decision on selection of resilience measures and the development of strategies to enhance resilience, outlining a path to co-build resilience action plans, and to track resilience progress in the city or service over time. This paper presents the framework and the main results of its application to three cities having diverse contexts. It was demonstrated that the framework highlights where cities and urban services stand, regarding resilience to climate change, and identifies the most critical aspects to improve, including expected future impacts.

As construções antigas fazem parte do tecido histórico das cidades, pelo que é importante proceder a intervenções de reabilitação eficientes, mas não destruidoras da sua identidade e valor cultural intrínseco. A utilização de rebocos armados apresenta-se como uma solução simples e eficaz no reforço sísmico deste tipo de construções, nos casos em que não é possível ou exigível a preservação dos revestimentos de paredes. Neste artigo, são analisadas várias composições de rebocos armados, constituídos por ligantes à base de cal aérea, cal hidráulica ou cimento, com um traço usual e com armaduras constituídas por redes metálicas, redes de fibra de vidro e uma rede de fibra natural. É analisada a capacidade resistente à tração desses revestimentos armados, assim como aspetos que podem influenciar a compatibilidade com os materiais existentes, apresentando-se as principais vantagens e desvantagens dos vários tipos de revestimentos.

Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced by historical decisions and implementations. The current decisions taken in sewer asset management will, therefore, have a long-lasting impact on the functionality and quality of future services provided by these networks. These decisions can be supported by different approaches ranging from various inspection techniques, deterioration models to assess the probability of failure or the technical service life, to sophisticated decision support systems crossing boundaries to other urban infrastructure. This paper presents the state of the art in sewer asset management in its manifold facets spanning a wide field of research and highlights existing research gaps while giving an outlook on future developments and research areas.

The current program of Systematic Observation of Maritime Works (OSOM+), under development at the National Laboratory for Civil Engineering (LNEC), is essentially applied to rubble mound breakwaters. The OSOM’s main objective is to monitor the behaviour of maritime structures under inspection and recommend timely interventions for their maintenance and/or repair as to properly maintain its function during its lifetime. There are four main components of the OSOM+ program, namely: the periodic visual inspections made by a trained technician, where a set of photos and videos are taken at notable points along the structure and there is an identification of the main focuses of degradation of the structure; the periodic aerial inspections with an unmanned aerial vehicle (UAV) or drone, where individual aerial photographs are captured in a regular pattern and in the vertical direction, and from them orthomosaics, point clouds and/or profiles are obtained; the ANOSOM_WEBbased online platform, to store and/or query obtained information on the observation campaigns, as well as to diagnose present, evolution and risk conditions of the structure; and a mobile, portable, application for real-time input and visualization of the database information. This paper presents an application of the OSOM+ program to the study case: the west breakwater of the port of Sines.