Browsing by Author "Sousa, R."
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- Choosing sheep (Ovis aries) as animal model for temporomandibular joint research: Morphological, histological and biomechanical characterization of the joint discPublication . Angelo, D.F.; Morouço, P.; Alves, N.; Viana, T.; Santos, F.; González, R.; Monje, F.; Macias, D.; Carrapiço, B.; Sousa, R.; Cavaco-Gonçalves, S.; Salvado, F.; Peleteiro, C.; Pinho, M.Preclinical trials are essential to the development of scientific technologies. Remarkable molecular and cellular research has been done using small animal models. However, significant differences exist regarding the articular behavior between these models and humans. Thus, large animal models may be more appropriate to perform trials involving the temporomandibular joint (TMJ). The aim of this work was to make a morphological (anatomic dissection and white light 3D scanning system), histological (TMJ in bloc was removed for histologic analysis) and biomechanical characterization (tension and compression tests) of sheep TMJcomparing the obtained results with human data. Results showed that sheep processus condy-laris and fossa mandibularis are anatomically similar to the same human structures. TMJ dischas an elliptical perimeter, thinner in the center than in periphery. Peripheral area actsas a ring structure supporting the central zone. The disc cells display both fibroblast andchondrocyte-like morphology. Marginal area is formed by loose connective tissue, with somechondrocyte-like cells and collagen fibers in diverse orientations. Discs obtained a tensile mod-ulus of 3.97 ± 0.73 MPa and 9.39 ± 1.67 MPa, for anteroposterior and mediolateral assessment.The TMJ discs presented a compressive modulus (E) of 446.41 ± 5.16 MPa and their maximumstress value ( max) was 18.87 ± 1.33 MPa. Obtained results suggest that these animals should beconsidered as a prime model for TMJ research and procedural training. Further investigationsin the field of oromaxillofacial surgery involving TMJ should consider sheep as a good animalmodel due to its resemblance of the same joint in humans.© 2016 Elsevier Masson SAS. All rights reserved.
- Historic Appraisal Review and Geometric Characterization of Old Masonry Buildings in Lisbon for Seismic Risk AssessmentPublication . Bernardo, V.; Sousa, R.; Candeias, P.; Costa, A.; Costa, A. CamposThe Metropolitan Area of Lisbon (MAL) has the highest population and building density in Portugal, and is exposed to medium to high magnitude earthquakes due to its geographical location. Currently, the MAL housing stock is constituted by approximately 35% of masonry residential buildings with a large variability of materials and construction techniques, as a result of many centuries of history. Most of these buildings were built before the introduction of the first design code for building safety against earthquakes (RSSCS) in Citation1958 and therefore were only designed to support gravity loads. Given the presence of these buildings in areas of significant seismicity, a comprehensive research is needed to assess the seismic risk and define mitigation policies for this population of unreinforced masonry buildings. The main purpose of this work is thus to geometrically characterize these typologies, through an exhaustive survey of dozens of masonry buildings collected from original drawings and identify the most important aspects that can influence their seismic behavior. After a compressive historical background, the information collected is statistically analyzed and expressed through probability distributions that can be used for the development of numerical models and derive seismic vulnerability functions, fundamental to conduct seismic risk analyses.
- Seismic fragility functions for Portuguese RC precast buildingsPublication . Sousa, R.; Batalha, N.; Silva, V.; Rodrigues, H.Fragility functions are fundamental for the assessment of seismic safety of structures or the loss assessment of a portfolio of assets. The present paper describes a procedure to derive fragility functions representative of Portuguese reinforced concrete precast buildings. This goal was achieved following an analytical methodology considering the result of hundreds of nonlinear static analyses, whose building models reflect both mechanical and geometrical characteristics of the Portuguese industrial building stock. Considering the specificities of this typology, and in particular the connections between the structural members, a recently developed macro-element was employed, which enables the explicit simulation of friction and dowel mechanisms. The fragility analyses considered both structural and non-structural limit states, and the findings indicate a poor seismic performance, even under low seismic demand.