Artigos de Revista

External Thermal Insulation Composite Systems (ETICS) are frequently used to enhance the energy efficiency of the built environment. However, stains of presumable biological nature are often detected shortly after application, causing cladding defacement and altering the building aesthetics. To address which microbiota could contribute to these biodeterioration related color/aesthetic anomalies, samples collected from stains detected on the surface of building facades with ETICS in three residential sites in Lisbon, Portugal, were analyzed through microbiological culture-dependent technique and culture-independent amplicon DNA high throughput sequencing taxonomic profiling. The obtained data provided a comprehensive description of microbial communities assigned to diverse taxa of the major microbial groups of heterotrophic bacteria, fungi, cyanobacteria, and microalgae (through DNA plastid detection) in the sampled stains. Based on that, we propose that new microorganisms could be added to the list of bio-susceptibility testing organisms in ETICS. Furthermore, microbiota diversity depended more on facade location and cardinal orientation than on ETICS material composition. Overall, this study reveals the unique microbial communities of color/aesthetic biodeterioration stains in ETICS facades, unlike those of other surfaces, and the associated environmental dynamics.

The durability of bond between carbon fibre-reinforced polymer (CFRP) laminates and concrete with theexternally bonded reinforcement (EBR) technique was investigated under real-time field exposure (RTFE) andaccelerated ageing. The experimental program, over two years, includes four outdoor environments inducingcarbonation, freeze

Masonry arches are a fundamental component of historical structures. The assessment of the vulnerability ofthese heritage constructions to seismic loading requires reliable and efficient numerical models. Discrete element models are an alternative to finite element models, being particularly effective in modelling collapse mechanisms created by shearing and separation of the units along the joints. Discrete element codes typically rely on explicit methods of integration of the equations of motion for dynamic analysis, which may require large run times when the recommended stiffness-proportional component of Rayleigh damping is applied. A novel approach is proposed using an alternative damping model, Maxwell damping, which involves placing multiple spring-dashpot elements in the joints, in parallel with the standard stiffness springs. This damping model is tested in the dynamic analysis of masonry arches, under pulse and earthquake loading. The results obtained in this early investigation show a good performance in the simulation of collapse under dynamic loads, in general agreement with the analyses conducted with classical stiffness-proportional damping, but reducing significantly the computational effort.

Laboratory tests were carried out to evaluate the feasibility of producing boards or coating panels with good hygrothermal performance by using different agro-industrial wastes (grape and olive press wastes, hazelnut shells, spent coffee and pine) and adhesives (gypsum-based binder, sodium silicate solution and starch-based glue). Hygrothermal properties and resistance to mould growth, including the effect of citric acid, were evaluated. The results highlighted the benefits and drawbacks of each adhesive: the binder seems more adequate to produce bio-based plastering mortars than boards; the other adhesives seem efficient solutions to produce boards with good hygrothermal properties; for the natural glue the bio-susceptibility needs improvement.

External Thermal Insulation Composite Systems (ETICS) are widely used constructive solutions which aim at enhancing the building thermal performance. Nevertheless, ETICS can often present anomalies (e.g., stains and microcracks) throughout their service life, and vandalism actions, as in the case of graffiti, are rather common in urban areas. The removal of undesired graffiti is generally carried out through invasive chemical

Traditional carpentry joints can be found worldwide in many timber truss structures connectingrafter and tie beam. One failure mode of this connection result from shear in the tie beam beyond the notch either due to bad design or deterioration. In this article, the reduction in shear strength of Single Step Joints (SSJ) resulting from biological attack by anobiids was analysed. For this purpose, tests were carried out in non-degraded scots pine (Pinus sylvestris L.) specimens (reference) and compared to artificially degraded specimens with three different levels of degradation. The reduction of shear resistance was analysed in relation to the density of holes drilled during the degradation simulation, the loss of mass, and the reduction of the hearresistant area. At lower degradation levels, no significant reduction in shear strength was observed. On the other hand, the linear regression shows a trend of resistance reduction with increasing degradation. Despite the relatively low coefficient of determination (r2 = 0.25), the parameterthat best correlated with the residual strength was the reduction in the shear-resistant area.

Traditional carpentry joints can be found worldwide in many timber truss structures connecting rafter and tie beam. One failure mode of this connection result from shear in the tie beam beyond the notch either due to bad design or deterioration. In this article, the reduction in shear strength of Single Step Joints (SSJ) resulting from biological attack by anobiids was analysed. For this purpose, tests were carried out in non-degraded scots pine (Pinus sylvestris L.) specimens (reference) and compared to artificially degraded specimens with three different levels of degradation. The reduction of shear resistance was analysed in relation to the density of holes drilled during the degradation simulation, the loss of mass, and the reduction of the shear-resistant area. At lower degradation levels, no significant reduction in shear strength was observed. On the other hand, the linear regression shows a trend of resistance reduction with increasing degradation. Despite the relatively low coefficient of determination (r2

The efects of climate change on the estuarine environment are not fully understood. In temperate regions, droughts are expected to increase in frequency and severity, due to lower precipitation, and the mean sea level is expected to rise. This study aimed to assess how the estuarine environment will be afected by river fow

Many collective irrigation systems have been operating for decades, facing high degradation of existing infrastructures and huge water-energy efficiency problems. Predominantly composed of open canals, they have been partially or entirely converted into pressurised pipe systems, implying a considerable increase in energy consumption and operation and maintenance costs. Simple, easy-to-use, and comprehensive approaches for energy efficiency assessment in collective irrigation systems are needed for diagnosis and assisting decision-making on implementing adequate improvement measures. This research proposes and demonstrates an innovative approach based on the water and energy balances and performance indicators to assess the effect of water losses, network layout and operation, energy recovery, and equipment on energy efficiency. A novel methodology for energy balance calculation is proposed for open canal, pressurised and combined systems. The application to a real-life open canal system and network areas allowed the identification of efficiency problems mainly due to water losses in canals, followed by the dissipated energy in friction losses. Less critical are pumping and manoeuvring equipment inefficiencies. Also, a considerable excess of gravity energy is recovered in hydropower plants. In raising pipe systems, in which shaft input energy predominates and costs for pumping play a key role, surplus and dissipated energy in friction losses are the most relevant issues. Significant energy is lost in the water conveyance and distribution in both systems. Consequently, the potential to improve energy efficiency through water loss management, network layout, and operation improvement, besides pumping and manoeuvring equipment replacement, is considerable.

Os ensaios de ligações aparafusadas realizados no LNEC no âmbito do projeto de investigação TimQuake abrangeram várias combinações de espécie (Pinus sylvestris e Picea abies) e teor de água da madeira, geometria da ligação (madeira-aço-madeira ou aço-madeira-aço), regime de carregamento e nível de tração axial do ligador.Este artigo apresenta o programa experimental e discute os resultados obtidos nos ensaios monotónicos, à luz do dimensionamento das ligações segundo o Eurocódigo 5 (EC5).Conforme previsto, as ligações com parafusos menos esbeltos apresentaram maior propensão para desenvolverem rotura frágil, mesmo seguindo a pormenorização recomendada no Eurocódigo 5. Os resultados dos ensaios con