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Contribuição ao estudo sobre o projeto estrutural de painéis em concreto pré-moldado
(Universidade Federal de São Carlos, 2016-09-12) Santos, Bruno Pereira dos; Almeida Filho, Fernando Menezes de; https://lattes.cnpq.br/0447825383222965; https://lattes.cnpq.br/5106318517975048
The use of building technologies as prefabricated concrete wall panels has been increasing as a common practice in the Brazilian market. An aspect in the use of panels in buildings, barely explored in Brazil, is the possibility of considering it actively contributing in responsiveness to loads imposed, interacting with other elements such as pillars, slabs and beams. Since it is known that the literature about the theme is very limited, and facing a new specific standard coming soon, ABNT NBR 16475 (2016), this study has as objective to review the concepts of design and dimensioning of precast wall panels. With a review of the most recognized literatures and previous research already made, as well as analysis of the current standards, is shown the major advances related to the research theme, as well the standards parameters and criteria used nowadays. Finally, it is exemplified in a mathematical model design, adopting the parameters and criteria mentioned on the standards studied, and the information obtained in the previous academic studies, making possible to bring discussions and analysis using parallels and comparisons, providing information that are subside for important conclusions for technical, academic and industrial segment of precast concrete, promoting an advance in the discussion of a very significant and actual theme.
Abordagem termodinâmica do transporte iônico e da relaxação estrutural em vidros fosfatos de prata
(Universidade Federal de São Carlos, 2016-09-12) Bragatto, Caio Barca; Souquet, Jean-Louis; https://lattes.cnpq.br/4581266109582900; Rodrigues, Ana Candida Martins; https://lattes.cnpq.br/4499231813051400; https://lattes.cnpq.br/5833076761496241
Ionic conductivity in glasses was first discovered and demonstrated by Warburg in 1884, but although it has been studied for over a century, the mechanisms underlying ionic conduction in glasses are not yet entirely clear. Glasses are commonly known to be electrical insulators, but some of them may present high conductivity and be candidates for different applications. The more conductive glasses result from the dissolution of halogenated salts in the glassy matrix, causing its ionic conductivity to increase by several orders of magnitude. Our approach proposes that glass can be compared to a solution in which a dissolved halogenated salt (solute) is weakly dissociated in the glassy matrix (solvent). This approach, called the weak electrolyte model, was initially proposed in the 70s to explain the almost exponential increase in the ionic conductivity of glasses in response to increasing concentrations of network modifiers (alkaline oxides). Our work proposes to expand this approach, correlating the increase in ionic conductivity with the increase in the thermodynamic activity of AgI. In addition, experiments were carried out at different temperatures in various glass compositions to confirm this correlation, using electromotive force (EMF) measurements to determine the thermodynamic activity and electrochemical impedance spectroscopy (EIS) measurements to determine the ionic conductivity of these glasses. Ionic transport was also used to examine the structural relaxation of AgPO3 glass. The glass was heated to another fictive temperature in the glass transition range and its ionic conductivity measured in situ by EIS. The kinetic parameters of the structural relaxation process, i.e., structural relaxation time ( ) and stretching parameter (β), were determined as a function of time by fitting the experimental data to KWW equations.