Artigos de Revista

Carbon fiber reinforced polymer (CFRP) composites can be used to strengthen existing reinforced concrete (RC) structures. The CFRP laminate can be bonded to RC structure using epoxy adhesive via near-surface mounted (NSM) strengthening technique. However, existing literature generally lacks data about durability of NSM CFRPto- concrete bond. In this study, strengthened concrete elements were exposed to laboratory-controlled environments (at approximately 20

The railway industry is seeking high-performance and sustainable solutions for sub-ballast materials, particularly in light of increasing cargo transport demands and climate events. The meticulous design and construction of track bed geomaterials play a crucial role in ensuring an extended track service life. The global push for sustainability has prompted the evaluation of recycling ballast waste within the railway sector, aiming to mitigate environmental contamination, reduce the consumption of natural resources, and lower costs. This study explores materials for application and compaction using a formation rehabilitation machine equipped with an integrated ballast recycling system designed for heavy haul railways. Two recycled ballast-stabilised soil materials underwent investigation, meeting the necessary grain size distribution for the proper compaction and structural conditions. One utilised a low-bearing-capacity silty sand soil stabilised with recycled ballast fouled waste (RFBW) with iron ore at a 3:7 weight ratio, while the second was stabilised with 3% cement. Laboratory tests were conducted to assess their physical, chemical, and mechanical properties, and a non-linear elastic finite element numerical model was developed to evaluate the potential of these alternative solutions for railway sub-ballast. The findings indicate the significant potential of using soils stabilised with recycled fouled ballast as sub-ballast for heavy haul tracks, underscoring the advantages of adopting sustainable sub-ballast solutions through the reuse of crushed deteriorated ballast material.

In line with the European Energy Performance of Building Directive (EPBD), this paper aims to calculate thecost-optimal energy performance of a residential building in southern Europe, more precisely in Portugal,taking into consideration thermal and lighting (daylighting and artificial lighting) refurbishment solutions. Theeconomic calculation method used considers the initial investment costs, the running costs (including annualmaintenance costs, operational costs, energy costs and periodic replacement costs), greenhouse gas emissionscosts and disposal costs. The results obtained for the energy needs allow choosing the cost-optimal package ofrefurbishment measures. It is shown in this paper the relevance of daylighting and artificial lighting solutionsfor the users

This paper investigates the influence of sea severity and mooring line pretension configuration on the operabilityof a moored vessel at a modified berthing site inside a port. A physical model was constructed to replicate thenew layout of the port of Leix

A wave flume is used to study a scaled model of a stepped bottom dual-chamber Oscillating Water Column (OWC) installed onshore. Compared to traditional single-chamber OWCs, the use of dual-chambers is expected to widen the range of sea states in which the OWC is more efficient, and the step, in front of the first chamber, boosts the capturing energy capacity of the device. The Power Take-Off (PTO) system is modelled as an air opening in the pneumatic chambers. Several experiments combining regular incident waves and PTO damping conditions are performed. Results of the amplitudes of the free surface elevations inside the chambers show that the device can amplify the incident wave amplitude up to 1.57 times in chamber 2. Results of the primary efficiency show that the device is highly dependent on the PTO damping characteristics and can reach around 40% for a wide range of wave periods. Results of the reflection analysis show that the reflection coefficient is also dependent on the PTO damping characteristics but remain lower than 0.6 for all the studied cases. Sloshing phenomenon (mostly in the cross-section direction) was observed for a wavelength close to the cross-section dimension, impacting negatively on the device pneumatic performance.

Laboratory experiments of wave propagation over rigid and flexible vegetation fields, with the same configurations, were conducted to understand the effect of vegetation flexibility on the drag coefficient (CD). The direct method and the least squares method (LSM), based on force and flow measurements, are applied to calculate the CD in the experimental conditions. The formulations of both methods are extended to estimate the CD for flexible vegetation cases. A video analysis was performed to account for the swaying motion. Typically, wave dissipation is lower for flexible than for rigid vegetation of the same configuration, under the same flow condition. Therefore, a proportional effect in the corresponding CD results, obtained from common CD calibration to wave dissipation without considering vegetation motion, is usually observed. However, the present results show that although the wave dissipation was 34% lower for flexible relative to rigid vegetation, the respective CD values were close. CD estimations considering vegetation motion and inertia suggest that CD of flexible vegetation was up to 13% higher relative to rigid vegetation. Accounting for inertia reduced the CD for rigid vegetation up to 7%, while raised the CD for flexible vegetation up to 13%.

The unreinforced masonry (URM) walls are the common load-bearing structural elements in most existing buildings, consisting of masonry units (bricks) and mortar joints. They indicate a highly nonlinear and complex behaviour when subjected to combined compression-shear load-ing influenced by different factors, such as pre-compression load and boundary conditions, among many others, which makes predicting their structural response challenging. To this end, the present study offers a discontinuum-based modelling strategy based on the discrete element method (DEM) to investigate the in-plane cyclic response of URM panels under different vertical pressures with and without a damp-proof course (DPC) membrane. The adopted modelling strategy represents URM walls as a group of discrete rigid block systems interacting along their boundaries through the contact points. A novel contact constitutive model addressing the elasto-softening stress-displacement behaviour of unit-mortar interfaces and the associated stiffness degradation in tension-compression regimes is adopted within the implemented discontinuum-based modelling framework. The proposed modelling strategy is validated by comparing a re-cent experimental campaign where the essential data regarding geometrical features, material properties and loading histories are obtained. The results show that while the proposed compu-tational modelling strategy can accurately capture the hysteric response of URM walls without the DPC membrane, it may underestimate the load-carrying capacity for URM walls with the DPC membrane.

Aquatic vegetation in the littoral zone plays a crucial role in attenuating wave energy andprotecting coastal communities from hazardous events. This study contributes to the developmentof numerical models aimed at designing nature-based coastal defense systems. Specifically, a novelnumerical application for simulating wave

As fichas de rendimento de operações de construção, contendo informação sobre os recursos, os rendimentos e os preços unitários das atividades, assumem um papel importante no planeamento económico da construção. No caso particular das soluções de reforço de elementos de betão armado, não existem, até à data, fichas de rendimento para esse tipo de operações. Neste sentido, foi realizado um estágio profissional para a Ordem dos Engenheiros, no Laboratório Nacional de Engenharia Civil (LNEC), tendo em vista a elaboração de fichas de rendimento para diferentes soluções de reforço de elementos de betão armado: chapas de aço coladas, chapas de aço aparafusadas, laminados de compósitos reforçados com fibras de carbono colados e betão projetado. Foi utilizada, para o efeito, a estrutura de informação das fichas de rendimento do LNEC

Fire is one of the most damaging deterioration agents in a short time of action. It can cause considerable damage, leading to the loss of lives and possessions. Concerning fire safety recommendations, buildings must be protected by an integrated system of passive and active measures. Two passive measures widely used in many industries are fire-retardant and fire-resistant coatings. These systems provide a fire-protective layer to the surfaces of flammable and non-flammable materials, delaying or preventing their ignition, reducing the heat transfer from the source to the substrate and decreasing the flame spread and the release of smoke and toxic gases. When exposed to fire, according to the different mechanisms of action, fire-protective coatings (FPC) can be classified as non-intumescent and intumescent. Despite being widely mentioned in heritage fire safety guidelines, studies on their application in the field are still scarce. Namely, research on the safety and efficacy of their application near collections (in support materials) and systematic studies comparing different formulations. Therefore, this research assembles interdisciplinary studies on the use of FPC to deepen knowledge and theoretically identify the feasibility of their application in collection support/storage materials or exhibition furniture (bookshelves, cabinets, plinths) in heritage environments.