Papers
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Close-range photogrammetry for 3D rock joint roughness evaluation
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 Grassellis 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.
Year: 2022
Author(s): Paixão, A.; Muralha, J.; Resende, R.; Fortunato, E.
: Rock Mechanics and Rock Engineering
Editor: Springer
Keywords: Multi-view stereo; Structure-from-motion; Photogrammetry; Roughness; Rock joints
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ComparaÆo de tcnicas fotogramtricas na reconstituiÆo digital do modelo f¡sico 3D do prolongamento do molhe do Porto de Sines
Neste trabalho sÆo apresentados os resultados da comparaÆo entre trs metodologias para obtenÆo de modelos tridimensionais de superf¡cie, aplicadas
situaÆo espec¡fica do modelo f¡sico 3D do prolongamento do molhe leste do porto de Sines.
Year: 2022
Author(s): Fortes, C. J. E. M.; Lemos, R.; CapitÆo, R.
Editor: PIANC
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Computational investigations on the combined shear
This research explores the mechanical behavior of dry-joint masonry subjected to combined shear
Year: 2022
Author(s): Hazzard, J.; Lemos, J. V.; Loureno, P.; Gonen, S.; Pulatsu, B.
: Computational Particle Mechanics
Editor: Springer
Keywords: discrete elements; numerical modelling; masonry
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Considerações sobre direitos e problemas dos idosos - versão de trabalho e base bibliográfica # 838 Infohabitar
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.
Year: 2022
Number Pages:
16.
Author(s): Baptista Coelho, A.
: Infohabitar
Editor: GHabitar - Associação Portuguesa para a Promoção da Qualidade Habitacional
Volume:
Ano XVIII, n.º 838.
Keywords: programa de habitação adaptável intergeracional cooperativa a custos controlados; phai3c; intergeracionalidade; habitação
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Context-Based Multi-Agent Recommender System, Supported on IoT, for Guiding the Occupants of a Building in Case of a Fire
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%.
Year: 2022
Number Pages:
30pp.
Author(s): Neto, J.; Morais, A.J.; Gonçalves, R.; Leça Coelho, A.
: Journal Electronics (https://www.mdpi.com/journal/electronics)
Editor: MDPI
Volume:
Electronics 2022, 11, 3466..
Keywords: building occupant guidance; occupant behavior conditioning; ontologies; fire building evacuation; IoT
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Damage Evolution Prediction during 2D Scale-Model Tests of a Rubble-Mound Breakwater: A Case Study of Ericeira
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
Year: 2022
Author(s): Fortes, C. J. E. M.; Santos, J. A.; Lemos, R.
: Modelling
Editor: MDPI
Keywords: rubble-mound breakwater; damage evolution; position sensor
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Deduction of ultimate equilibrium limit states for concrete gravity dams keyed into rock mass foundations based on large displacement analysis
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.
Year: 2022
Number Pages:
1180-1190.
Author(s): Pereira, R.; Batista, A. L.; Neves, L.; Lemos, J. V.
: Structures
Editor: Elsevier
Volume:
38.
Keywords: Large displacement analysis; Ultimate equilibrium; Limit state approach; Analytical modeling; Stability analysis; Keyed profiles; Concrete gravity dams
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Deduction of ultimate equilibrium limit states for concrete gravity dams keyed into rock mass foundations based on large displacement analysis
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.
Year: 2022
Author(s): Lemos, J. V.; Neves, L.; Batista, A. L.; Pereira, R.
: Structures
Editor: Elsevier
Volume:
38
Keywords: Large displacement analysis; Ultimate equilibrium; Limit state approach; Analytical modeling; Stability analysis; Keyed profiles; Concrete gravity dams
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Desempenho de um dispositivo de aproveitamento da energia das ondas do tipo coluna de gua oscilante integrado em trs tipos de estruturas de proteÆo portu ria
Os dispositivos de aproveitamento da energia das ondas do tipo Coluna de µgua Oscilante (CAO) podem ser inseridos em proteäes portu rias, tais como os quebra-mares verticais e de talude e quebra-mares sobre estacas. Assim, a interaÆo 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 trs configuraäes 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 (potncia pneum tica m xima de 70 kW), sendo que a potncia pneum tica globalmente 3 % maior do que a do CAO inserido no quebra-mar de talude (potncia 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 eficincia significativa para per¡odos de onda maiores.
Year: 2022
Author(s): Teixeira, P.; Didier, E.
Editor: ENMC, XIII ECTM
Keywords: RANS; Modelagem numric; Quebra-mar vertical; Quebra-mar de talude; Coluna de gua oscilante
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DeterminaÆo do espraiamento em quebra-mares de talude atravs da metodologia TimeStack e atravs de sonda resistiva. Uma an lise comparativa
O objetivo deste trabalho a comparaÆo de duas metodologias utilizadas na avaliaÆo do espraiamento durante os ensaios em modelo f¡sico bidimensional dos quebra mares de proteÆo dos portos de Peniche e da Ericeira, realizados no mbito do projeto BSafe4sea. As metodologias utilizadas foram a tradicional mediÆo 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 condiäes de teste. Em relaÆo 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 tcnicas 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 tcnica 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 instalaÆo fixa da cmara, para melhorar a precisÆo dos resultados obtidos com esta tcnica.
Year: 2022
Author(s): Rito, J.; Andriolo, U.; Fortes, C. J. E. M.; Fontes, R.; Lemos, R.
Editor: XXV ENMC
Keywords: Quebra-mar; Modelo F¡sico; TimeStack; An lise de video; Espraiamento
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