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- Seismic retrofitting of an existing masonry school building: a case study in AlgarvePublication . Estêvão, João M. C.; Tomás, Bruno; Laranja, Roberto; Braga, Alfredo Manuel Gonçalves SilvaOne of the goals of the PERSISTAH project is the seismic assessment of primary school buildings existing in Algarve (Portugal) and Huelva (Spain) regions, and to propose retrofitting solutions for the buildings that present a high seismic risk level. These solutions are to be implemented in two pilot school buildings, one in the Algarve and the other in Huelva. The most vulnerable school buildings that were identified in Algarve were the masonry buildings, which were built before the existence of modern seismic codes. The primary school selected for retrofitting is located at Bracanes (Olhão). At first, a nonlinear seismic static analysis was carried out using the N2 method, trying to apply advanced seismic analysis methods to practical problems. This led to the conclusion that the existing building does not comply with the seismic level established in the NP EN1998-3:2017 code (EC8-3). Because there is already a rigid roof system, the selected retrofitting strategy is the consolidation of the vertical structure, namely applying one solution presented in the EC8-3. This case study has shown the difficulties of applying the EC8-3 to the Algarve region, and what it is possible to do to overcome those problems.
- Utilização de ensaios dinâmicos na avaliação da segurança de estruturas: caso de estudoPublication . Laranja, Roberto; Carreira, A. S.; Estêvão, João M. C.A vibração induzida por máquinas rotativas é um problema que pode afetar o regular funcionamento de um sistema estrutural bem como o conforto dos utilizadores expostos, dado que o ser humano é sensível às vibrações, designadamente quando são ultrapassados determinados níveis de aceleração. Isso pode originar a sensação de desconforto e problemas de saúde, pelo que é da maior importância a medição desses níveis de vibração. Além disso, a vibração continuada poderá originar fenómenos de fadiga nos sistemas estruturais. Neste trabalho, é apresentado um caso de estudo onde é ilustrada a utilização de ensaios dinâmicos in situ, nomeadamente como forma de apoio à realização da avaliação da segurança última e em serviço de um edifício industrial em betão armado, que apresentava indícios de existirem anomalias estruturais, e onde os trabalhadores sentiam as vibrações induzidas pelas máquinas da fábrica
- Silves bridge geometric model via structure-from-motion: tool for heritage digital catalogsPublication . Prates, Gonçalo; Marçal Gonçalves, Marta; Lopes, Ana; Laranja, RobertoThe old bridge in Silves, Portugal, has five perfectly formed arches extending over the Arade river with about 76 meters long built of local materials. In the 14th century this structure was rebuilt on the location of a previous structure built when Silves was the Moorish capital between the 8th and 13th centuries occupation of the Algarve. Though a Roman road might have crossed this area, there is no medieval descriptions mentioning a bridge in Silves, still it is also known as the Roman bridge.After interventions in the 14th, 17th, 18th and 20th centuries, the bridge was classified as monument of public interest and became pedestrian-only and frequently evaluated for its risk of collapse. Stereo-photogrammetry is a recognized surface reconstruction tool applied for almost one century, where from several overlapping images of the surface a 3D model can be obtained. Contrasting with classical stereo-photogrammetry, Structure-from-Motion (SfM) is a nearly automated compilation of digital imagery processing strategies that solve for camera position and surface geometry using matching features identified in several images from diverse perspectives and preferably with high degree of overlap. Together with ongoing increase in computer power, SfM allowed digital stereophotogrammetry to be operative for close-range, high-resolution and non-metric overlapping digital images, and cost-effective. Applying these nearly automated strategies to digital images of the old bridge in Silves taken from the surrounding grounds, a dense point-cloud was computed providing its complete digital model allowing accurate measurements and materials visual identification, key elements for heritage digital catalogs and historical building information models.