Artigos de Revista

Photogrammetry-based methods using everyday photographic equipment and easily available software have gained relevance for roughness measurement of rock joints, as an alternative to traditional approaches. However, the influence of some aspects, such as the number and orientation of camera poses, the parameters of the Structure-from-Motion, Multi-View Stereo and meshing algorithms, the resolution and accuracy of the reconstructed models, requires proper appraisal. To assess the surface roughness of a granite rock joint specimen using such photogrammetry methods, 3D models generated using different settings (i.e. camera sensors, camera poses, open/free software and workflows) were compared with a reference model obtained by contact digitalization. The results suggest that comparable results can be achieved if the photos adequately cover the specimen and, at least, equivalent vertex densities are attained. Percentiles p5 and p95 of surface deviations of the tested models to the reference mesh were, in general, lower than ±0.1 mm. Estimated roughness parameters showed reduced variability, with a minor impact on the shear strength evaluated according to the Grasselli’s GG-shear strength criterion, which was developed from the empirical correlation of roughness parameters with laboratory testing data. Results also showed that this methodology is far more accessible, easier to use, faster to implement, and less expensive than most currently available equipment and approaches.

Neste trabalho sÆo apresentados os resultados da compara‡Æo entre trˆs metodologias para obten‡Æo de modelos tridimensionais de superf¡cie, aplicadas … situa‡Æo espec¡fica do modelo f¡sico 3D do prolongamento do molhe leste do porto de Sines.

This research explores the mechanical behavior of dry-joint masonry subjected to combined shear

As presentes notas de leitura e de reflexão partem de um enquadramento feito através de um importante relatório mundial sobre envelhecimento e saúde para se desenvolver uma referência ampla à importante Estratégia Nacional para o Envelhecimento Ativo e Saudável (ENEAS), e, depois, para uma abordagem sintética do direito à habitação na perspetiva do idoso, tendo por base diversos documentos.Há que fazer, aqui, uma referência específica a estarmos a entrar em áreas tão sensíveis como especializadas e que portanto têm de ser desenvolvidas no respeito dos respetivos especialistas, mas julga-se que para o avançar de ideias de conceção minimamente adequadas para uma habitação intergeracional, importa avançar nessas áreas ainda que, para já, apenas de uma forma exploratória ou introdutória.

Abstract: The evacuation of buildings in case of fire is a sensitive issue for civil society that alsomotivates the academic community to develop and study solutions to improve the efficiency ofevacuating these spaces. The study of human behavior in fire emergencies has been one of the areasthat have deserved the attention of researchers. However, this modeling of human behavior is difficultand complex because it depends on factors that are difficult to know and that vary from countryto country. In this paper, a paradigm shift is proposed which, instead of focusing on modeling thebehavior of occupants, focuses on conditioning this behavior by providing real-time information onthe most efficient evacuation routes. Making this information available to occupants is possible witha solution that takes advantage of the growing use of the IoT (Internet of Things) in buildings to helpoccupants adapt to the environment. Supported by the IoT, multi-agent recommender systems canhelp users to adapt to the environment and provide the occupants with the most efficient evacuationroutes. This paradigm shift is achieved through a context-based multi-agent recommender systembased on contextual data obtained from IoT devices, which recommends the most efficient evacuationroutes at any given time. The obtained results suggest that the proposed solution can improve theefficiency of evacuating buildings in the event of a fire; for a scenario with two hundred peoplefollowing the system recommendations, the time they take to reach a safe place decreases by 17.7%.

Melby presents a formula to predict damage evolution in rubble-mound breakwaters whose armour layer is made of rock, based on the erosion measured in scale-model tests and the characteristics of the incident sea waves in such tests. However, this formula is only valid for armour layers made of rock and for the range of tested sea states. The present work aims to show how the Melby methodology can be used to establish a similar formula for the armour layer damage evolu tion in a rubble-mound breakwater where tetrapods are employed. For that, a long-duration test series is conducted with a 1:50 scale model of the quay section of the Ericeira Harbour breakwater. The eroded volume of the armour layer was measured using a Kinect position sensor. The damage parameter values measured in the experiments are lower than those predicted by the formulation for rock armour layers. New

Concrete gravity dams are mass concrete structures, often built on rock mass foundations, conceived to rely upon their weight for stability. To prevent sliding, these structures are usually keyed/embedded into the foundation, a good construction practice particularly relevant in medium to high intensity seismic zones. In stability analysis, the extra strength obtained by keying the dam into the foundation is usually either neglected or taken as a passive resistance, which, such as explored in this paper, do not reflect the real structural response in pre-collapse situations. Limit state philosophy requires the ultimate equilibrium conditions to be expressed as accurately as possible. In this paper, the rigid-body equilibrium of a wedgy model representing the dam and a downstream rock wedge is analyzed according to the large displacement regime. Failure mechanisms were identified, analytically described and numerically validated. Application to two Portuguese large concrete gravity dams led to safety factors considerably larger than those computed assuming the usual practice. The proposed approach is intended to support probabilistic and/or semi-probabilistic methodologies for safety assessment of concrete gravity dams, in the design and feasibility phases, in which the limit state approach is inherently followed.

Concrete gravity dams are mass concrete structures, often built on rock mass foundations, conceived to rely upon their weight for stability. To prevent sliding, these structures are usually keyed/embedded into the foundation, a good construction practice particularly relevant in medium to high intensity seismic zones. In stability analysis, the extra strength obtained by keying the dam into the foundation is usually either neglected or taken as a passive resistance, which, such as explored in this paper, do not reflect the real structural response in pre-collapse situations. Limit state philosophy requires the ultimate equilibrium conditions to be expressed as accurately as possible. In this paper, the rigid-body equilibrium of a wedgy model representing the dam and a downstream rock wedge is analyzed according to the large displacement regime. Failure mechanisms were identified, analytically described and numerically validated. Application to two Portuguese large concrete gravity dams led to safety factors considerably larger than those computed assuming the usual practice. The proposed approach is intended to support probabilistic and/or semi-probabilistic methodologies for safety assessment of concrete gravity dams, in the design and feasibility phases, in which the limit state approach is inherently followed.

Os dispositivos de aproveitamento da energia das ondas do tipo Coluna de µgua Oscilante (CAO) podem ser inseridos em prote‡äes portu rias, tais como os quebra-mares verticais e de talude e quebra-mares sobre estacas. Assim, a intera‡Æo entre a onda incidente e a estrutura na qual o dispositivo de aproveitamento da energia das ondas ‚ integrado ‚ significativamente diferente, j  que, no caso de um quebra-mar vertical, a estrutura ‚ imperme vel e que, no caso de um quebra-mar de talude, a estrutura ‚ porosa. O desempenho do dispositivo de CAO para estas trˆs configura‡äes ‚ analisado para um intervalo de per¡odo de onda incidente regular entre 6 e 12 s e uma altura de onda de 1 m. O dispositivo de CAO integrado no quebra-mar vertical apresenta o maior desempenho (potˆncia pneum tica m xima de 70 kW), sendo que a potˆncia pneum tica ‚ globalmente 3 % maior do que a do CAO inserido no quebra-mar de talude (potˆncia pneum tica m xima de 67,4 kW). O desempenho do dispositivo de CAO integrado no quebra-mar sobre estacas ‚ similar ao do dispositivo em quebra-mar vertical para os per¡odos de onda inferiores a 9 s, mas apresenta uma perda de eficiˆncia significativa para per¡odos de onda maiores.

O objetivo deste trabalho ‚ a compara‡Æo de duas metodologias utilizadas na avalia‡Æo do espraiamento durante os ensaios em modelo f¡sico bidimensional dos quebra mares de prote‡Æo dos portos de Peniche e da Ericeira, realizados no ƒmbito do projeto BSafe4sea. As metodologias utilizadas foram a tradicional medi‡Æo da altura de espraiamento com uma sonda resistiva e uma metodologia baseada em an lise de v¡deos, tendo sido avaliado o seu desempenho para diversas condi‡äes de teste. Em rela‡Æo aos resultados obtidos, em termos de Ru2% e Rumax, verificou-se que o andamento e a ordem de grandeza dos valores obtidos com as duas t‚cnicas eram bastante semelhantes, embora os valores obtidos pela an lise do v¡deo tenham sido, em geral, superiores aos obtidos pela sonda. Constatou-se, assim, que a t‚cnica de imagem de v¡deo ‚ uma alternativa vi vel para medir o espraiamento. Recomenda-se, no entanto, o uso de luz difusa durante os testes, bem como a instala‡Æo fixa da cƒmara, para melhorar a precisÆo dos resultados obtidos com esta t‚cnica.