Artigos de Revista

Recently, water utilities have been making considerable investments in sewers' monitoring; however, in most cases, assuring data reliability is yet a challenge. Often, hydraulic data is collected in sewers overlooking best practice aspects. Assuming confidence in data, while disregarding cautions verifications, might lead to inadequate uses of data. The paper presents a methodology aiming to narrow the gap between science and industry, regarding monitoring programs in urban drainage. A procedure to enhance hydraulic data reliability, in line with ISO/IEC 17025:2017, was developed, applied and validated, enabling a final evaluation on data and site adequacy and an overall identification of improvement opportunities. The availability of a valuable case study comprising 32 flowmeters from Portuguese utilities, in eastern Europe, presented an opportunity to create a story line, test the procedure's coherence, present it to the technical community and evaluate the constraints that utilities, in their everyday working context, are faced with. The procedure is presented in detail and a collection of examples of its application is shown. In the final evaluation, most monitoring stations' alignment with best practice requirements were either high (25%) or acceptable (44%), regarding their overall performance and compliance with both data and site adequacy. For all of them, improvement opportunities were identified.

The present work analyses the wind load effects on the 516 Arouca bridge, the world's longest pedestrian suspension bridge in 2020. Computational fluid dynamics (CFD) was used to model a range of wind incidence angles between -8? and +8?. The simulations were performed by solving the steady-state Reynolds averaged Navier-Stokes (RANS) equations with the k-? shear stress transport (SST) model. The simulations were carried out for different bridge configurations to determine the influence of the upper guard of the tray deck and the suspended cables on the generated loads. The numerical results were validated by performing different wind tunnel tests using a reduced scaled prototype. The predicted aerodynamic characteristics showed good agreement with the experimental results. Furthermore, the drag forces obtained from the numerical analysis agree with the computed values from the Eurocode (NP EN 1991-1-4:2010) for different inlet wind velocities, ranging from 3.91 m/s to 52.84 m/s.

An experimental study was carried out to investigate seabed-pipeline interactions with regard to soil liquefaction. For a soil with a high proportion (30 to 60%) of fine sediment, four groups of tests were configured to reproduce soil liquefaction around pipelines for different initial pipe depths, pipe densities and wave conditions (wave height and period). The study focused on verifying the theoretically computed areas of soil failure by analyzing the sinking depths of the pipelines. The main findings are that a pipe with a submerged specific weight of less than half that of the soil will move up to the mudline; that the loss of soil loading capacity is more frequently evidenced in a fluid-like behavior of the soil than by an abrupt breaking of the soil matrix; and that the pipes which are totally buried will sink more than half-buried pipes. Moreover, wave action and the specific weight of the pipes seem to play more important roles in the expected behavior of the wave–soil–pipe interaction than the initial water content of the mud.

The study of local scour in bridge foundations is often restricted to quantifying maximum scour depth on the upstream side. This is limiting to the understanding of the resulting scour by numerical methods, for which the shape of the scour hole is a mandatory input. In this work, two nonintrusive three-dimensional (3D) image-based measuring techniques, consisting of close-range photogrammetry and a Kinect V2 sensor, were employed to characterize the initial and final development of scour holes around piers, under steady flow in a laboratory flume. A novel two-dimensional (2D) methodology was also applied for continuous measurement of the side of the scour hole using submersible cameras. Models of the scour hole geometries in the vicinity of two oblong bridge piers were obtained at high accuracy levels. A database for calibration and validation of numerical models is thus provided.

Multilayer external wall thermal insulation systems are widely used in new constructions and for the retrofitting of building façades. Despite the increasing use as constructive solution, significant anomalies have been frequently identified on these systems only few years after their application, raising questions on their long-term durability. This paper focuses on the effects of one-year natural ageing and artificial ageing through hygrothermal cycles (heat/rain and heat/cold) on the water performance (capillary water absorption and drying kinetics), bio-susceptibility (mould development) and surface properties (colour, gloss, and roughness) of four multilayer external wall thermal insulation systems (three ETICS and a thermal rendering system). Results showed a significant loss of surface hydrophobicity after ageing. Considering the 24 h water absorption results,an increase up to 73% and 432% was obtained for the naturally and artificially aged systems, respectively, and when compared to the reference unaged systems. The drying kinetics was affected by ageing, with increases of the drying resistance ranging between 47% and 122% after artificial ageing. Traces of mould growth were observed on the artificially aged systems; however, no growth was detected on either the unaged or the one-year naturally aged systems. Substantial colour change for all systems after ageing was observed, confirming aesthetic alteration. Results contribute towards the development of implemented artificial ageing protocols, as well as for the delivery of multilayer thermal systems with enhanced performance and durability.

Long motorway tunnels equipped with two independent unidirectional galleries are usually provided with longitudinal ventilation. This ventilation scheme, when applied to smoke control, can generate significant pressure differences between both roadway galleries, which may have an impact on the use of transverse galleries (escape routes). This paper present two-case studies where the results of measure- ments of these pressure differences taken in Mara ?o and Gardunha tunnels allowed the assessment of relevant flow parameters, as the pressure loss coefficient of the entrance portal, the friction factor in the tunnel and the coefficient of installation of the jet fans. The assessed parameters were used in the steady-flow energy equation for a streamtube to predict the impact of pressure differences on the protection of trans- verse galleries (emergency exits) in the case of fire. The results show that the pre- dicted pressure in the fire road gallery increases upstream the location of the fire and decreases downstream that location, when taking the pressure profile of the flow without fire as a reference. The models show that predicted pressure differences between the two road galleries in case of fire may be within the interval [200 Pa; - 100 Pa] in Mara ?o tunnel and [12 Pa; - 48 Pa] in Gardunha Tunnel, while the mea- surements in the no fire case show that they lay within the interval [29 Pa; - 50 Pa] in Mara ?o tunnel and [- 13 Pa; - 35 Pa] in Gardunha Tunnel

Understanding the risks associated with the likelihood of extreme events and their respective consequences for the stability of hydraulic infrastructures is essential for flood forecasting and engineering design purposes. Accordingly, a hydrological methodology for providing reliable estimates of extreme discharge flows approaching hydraulic infrastructures was developed. It is composed of a preliminary assessment of missing data, quality and reliability for statistically assessing the frequency of flood flows, allied to parametric and non-parametric methods. Model and parameter uncertainties are accounted for by the introduced and proposed modified model averaging (modified MM) approach in the extreme hydrological event's prediction. An assessment of the parametric methods accuracy was performed by using the non-parametric Kernel Density Estimate (KDE) as a benchmark model. For demonstration and validity purposes, this methodology was applied to estimate the design floods approaching the case study ‘new Hintze Ribeiro bridge’, located in the Douro river, one of the three main rivers in Portugal, and having one of Europe's largest river flood flows. Given the obtained results, the modified MM is considered a better estimation method.

Water losses from water distribution means have a high environmental impact in terms of natural resource depletion (water, energy, ecosystems). This work aims to develop an optical airborne surveillance service for the detection of water leaks (WADI—Water-tightness Airborne Detection Implementation) to provide water utilities with adequate and timely information on leaks in water transportation mains outside urban areas. Firstly, a series of measurement campaigns were performed with two hyperspectral cameras and a thermal infrared camera in order to select the most appropriate wavelengths and combinations thereof for best revealing high moisture areas, which are taken as a proxy for water leakage. The Temperature-Vegetation-Index method (T-VI, also known as Triangle/Trapezoid method) was found to provide the highest contrast- to-noise ratio. This preliminary work helped select the most appropriate onboard instrumentation for two types of aerial platforms, manned (MAV) and unmanned (UAV). Afterwards, a series of measurement campaigns were performed from 2017 to 2019 in an operational environment over two water distribution networks in France and Portugal. Artificial leaks were introduced and both remote sensing platforms successfully detected them when excluding the unfavorable situations of a recent rain event or high vegetation presence. With the most recent equipment configuration, known and unknown real leaks in the overflown part of a water transportation network in Portugal have been detected. A significant number of false alarms were also observed which were due either to natural water flows (groundwater exfiltration, irrigation runoff and ponds) or to vegetation-cover variability nearby water-distribution nodes. Close interaction with the water utilities, and ancillary information like topographic factors (e.g., slope orientation), are expected to reduce the false alarm rates and improve WADI’s methodology performance.

O Aeroporto da Madeira é uma infraestrutura crítica com características estruturais únicas, o que motivou a monitorização do seu comportamento estrutural desde a construção da estrutura de ampliação da pista, que decorreu entre 1995 e 2000. O conhecimento adquirido do comportamento da estrutura em serviço, bem como a significativa evolução tecnológica, tornaram natural uma atualização do sistema de monitorização, tendo em vista o incremento de informação relevante para a gestão da sua conservação. Para além de novos sistemas de aquisição e comunicação, a atualização operada compreendeu a instalação de novas funcionalidades, designadamente a monitorização do movimento das juntas de dilatação e do comportamento dinâmico, quer através de acelerómetros e extensómetros em fibra óptica, quer por via de um sistema de correlação digital de imagem. Nesta comunicação é brevemente descrito o sistema de monitorização original, bem como os novos sensores e alguns dos resultados iniciais, que se afiguram promissores.

This paper describes a numerical evaluation of optimal sizes of a Wells turbine and chamber cross section to be used in a cluster of an oscillating water column (OWC) wave energy converter device. The FLUENT numerical model, based on the Reynolds–averaged Navier–Stokes equations and the volume of fluid technique, is used for modeling hydrodynamic and aerodynamic flows. Two new methods are developed for diminishing the computational cost: the generalized–TDO (turbine diameter optimization) model and the HAS (hydro-aerodynamic similarity) model. The generalized–TDO model is developed to determine the optimal turbine diameter for an OWC chamber with a square cross section. The analytical HAS model employs a similitude method to extend results obtained for a square cross section of the OWC chamber to a rectangular one. The optimal length, B, and width, W, of the chambers and turbine diameter, D, chosen by taking into account the southern Brazilian wave climate, were B ×W=15 × 15 m2 and D=2.75 to 3.00 m and 20 × 20 m2 and D=3.25 to 3.50 m, with efficiencies of 51% and 49%, respectively. Same optimal annual efficiency can be obtained for rectangular cross-section chambers 15 ×W and 20 ×W by using an adequate turbine diameter defined by the HAS model.