Browsing by Issue Date, starting with "2021-02-24"
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- O que é uma explicação matemática? Sardinhas, pontes e cigarrasPublication . Castro, EduardoPor que razão não consigo dividir sete sardinhas inteiras por três gatos? Por que razão não consigo atravessar as sete pontes de Königsberg, uma só vez e numa única caminhada?1 Por que razão a espécie Magicicada de cigarras da América do Norte tem ciclos de vida ímpares, de 13 ou 17 anos?
- Analysis of the Structural Efficiency of Arch Bridges with High Strength Concrete Filled TubesPublication . Hummeid, Mohamad Maher; Pinto, Clemente MartinsConcrete-filled steel tubes (CFST) have been increasingly applied in long span arch bridges due to their high compressive strength and efficiency in construction. The objective of this work is to evaluate the efficiency of using high strength concrete in long span CFST arch bridges. Experimental results on the behaviour of CFST elements were collected from literature, aiming to analyze the behaviour of high strength concrete in CFST solutions. The analysis of the results was based on the internal mechanical behaviour and failure mechanism of the concrete core and their effect in the loading capacity of CFST sections. The analysis has shown that the different behaviour between normal and high strength concrete results in different effects concerning the confinement level and the loading capacity of CFST sections. The steel tube changes the cracking process of the concrete core, contributing to an unfavorable failure mode in case of high strength concrete, which reduces the efficiency of the combination of the steel tube and the high strength concrete core. An initial design of a long span railway CFST arch bridge was carried out, considering two combinations of materials, namely normal and high strength materials. The application of high strength materials shows the advantages of reducing the structure self-weight and the materials consumption by about the half when compared to normal strength materials.
- Assessment model for vernacular limestone buildings using Microsoft Excel®: the case of Serra de Santo AntónioPublication . Faria, Ana Luísa Vieira; Virtudes, Ana Lidia Moreira Machado Santos dasThis dissertation intends to survey and study the state of conservation of the vernacular limestone buildings in Serra de Santo António. This village, located in the PNSAC (Parque Natural das Serras de Aire e Candeeiros) in central Portugal, is known for its limestone constructions, including walls used by shepherds and farmers as boundaries of land and as a fence, the so-called Casinas, buildings housing and windmills. The main goals of this dissertation are to create a model for the evaluation (of the state of conservation and proximity to the original architectural matrix) of limestone buildings using Microsoft Excel?. This model will subsequently be applied to a sample of buildings in Serra de Santo António. The sample chosen is composed of twenty-four buildings that were evaluated with this model. However, the spreadsheet created in the software makes it possible to carry out new evaluations of the case studies later, as well as its application to other village areas, or to other locations where similar buildings exist. After the application of the evaluation model of vernacular stone buildings in Serra de Santo António, it is possible to conclude that none of the buildings analyzed is at level 1 of proximity to the architectural matrix, that is, in which the identity of its architecture is totally lost. It was also found that only 8% of buildings are at level 2 (according to which some original architectural and construction elements may have been removed or added) and that the vast majority of cases, about 92% are at level 3, that is, the highest being its current characteristics practically identical to those of the original construction. On the other hand, it is concluded that none of the buildings analyzed is at level 1 regarding the state of conservation, that is, in very poor condition, about 4% are at level 2 (in poor condition), 8% are at level 3 (average conservation condition), more than 16%) are at level 4 (in good condition) and the vast majority about 70% are at level 5, that is, in very good condition. In summary, most of the buildings are in very good condition and have maintained their vernacular architectural identity.