Orientador: João Alberto Venegas Requena / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-19T15:03:35Z (GMT). No. of bitstreams: 1 Minchillo_DanielaGrintaciVasconcellos_D.pdf: 6597615 bytes, checksum: 5e256a912f052806cb5166fe84151bf7 (MD5) Previous issue date: 2011 / Resumo: Este trabalho apresenta o desenvolvimento de uma concepção estrutural para ligações de treliças metálicas tubulares de seção circular com chapa de topo através de um estudo teórico-experimental. Nesta concepção as extremidades das diagonais são superpostas e unidas por um único parafuso fazendo com que a ligação seja pinada. A colocação da chapa faz com que apareça uma excentricidade na ligação originando esforços adicionais na estrutura que são aqui avaliados. Como vantagem desta ligação, destaca-se o baixo custo de fabricação, a rapidez de montagem das treliças, facilidade de transporte e versatilidade no detalhamento das ponteiras das diagonais. Pode ser utilizada em ligações de treliças planas ou multiplanares. Foi realizado um levantamento bibliográfico nas prescrições de cálculo e demais publicações, nacionais e internacionais, para ligações de estruturas tubulares, e um programa experimental foi desenvolvido com objetivo de certificar a ligação e obter um procedimento adequado para o cálculo da sua resistência. A análise experimental possibilitou a avaliação dos efeitos localizados na ligação, a interação entre a chapa e o perfil tubular e a identificação dos mecanismos de colapso. Os resultados experimentais são comparados com os resultados numéricos, que consideram como parâmetros, a influência do comprimento e da espessura da chapa de topo na resistência, no modo de colapso e na distribuição de tensões na ligação. Um modelo numérico, calibrado pelos resultados da análise experimental, foi utilizado para uma análise paramétrica. Com os resultados desta análise foi proposta uma formulação para obtenção da resistência da ligação / Abstract: This work presents a theoretical and experimental study of a gusset plate connection for application in trusses with circular hollow sections. In this connection the diagonals edges are superimposed and joined together at the plate by a single bolt causing the connection to be pinned. The placement of the plate leads to an eccentricity, resulting in additional efforts in the connection that are evaluated. Some of the advantages of this connection are the low manufacturing costs, the quickly assembly of trusses, versatility in the detailing of the braces ends and can be used properly on uniplanar or multiplanar trusses. A literature review is performed on codes, prescriptions and other publications, national and international for tubular connections, and an experimental program is developed in order to certify and obtain an appropriate procedure to determine the connection resistance. The experimental analysis allowed the evaluation of the local effects, the interaction between the gusset plate and tubular section and the identification of the failure modes. The experimental results are compared with numerical results considering parameters such as the influence of the length and thickness of the gusset plate in the connection resistance, failure mode and stress distribution. A numerical model, validated by the results of experimental analysis, was used for parametric analysis. With the parametric results, an analytical expression is proposed to predict the connection resistance / Doutorado / Estruturas / Doutor em Engenharia Civil

Wind power, especially offshore, is considered to be one of the most promising sources of ‘clean’ energy towards meeting the EU targets for 2020 and 2050. However, its popularity has always fluctuated with the price of fossil fuels since nowadays wind electricity production cannot compete with nuclear or coal electricity production. Support structures are thought to be one of the main drivers for reducing costs in order to make the wind industry more economically efficient. Foundations and towers should be fit for purpose, extending their effective service life but avoiding costs of oversizing. An exhaustive review of the background and state of the art of the Fatigue-Life assessment approaches has been carried out, combining analysis of the gathered experimental data and the development of Finite Element models based on contemporary 3D solid models with diverse Regression Analyses, in order to identify their weakness and evaluate their accuracy. This research shows that the guides and practices currently employed in the design and during the operation of the offshore wind turbine support structures are obsolete and not useful for optimisation, which generally leads to conservationism and an unnecessary increase in costs. The basis for a comprehensive update of the Girth Weld and Tubular Joint S-N curves and the Stress Concentration Factors of Tubular Joints has been set out. Furthermore, a reliable methodology for deriving the Stress Intensity Factor at the deepest point of a semi-elliptical surface saddle crack in a tubular welded T-joint has been proposed.

Orientador: João Alberto Venegas Requena / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-24T13:46:37Z (GMT). No. of bitstreams: 1 CoelhodaSilva_CatherineSoutoCosta_M.pdf: 3557954 bytes, checksum: afb90fa08dbf9c58642449f92217d07a (MD5) Previous issue date: 2014 / Resumo: O objetivo deste trabalho é apresentar um tipo de ligação em treliças metálicas tubulares multiplanares de seção circular com chapa de topo. Nestas ligações as extremidades das diagonais são superpostas e unidas por um único parafuso fazendo com que a ligação seja pinada. A colocação da chapa de topo implica no aparecimento de uma excentricidade na ligação originando esforços adicionais na estrutura. Esse tipo de ligação tem como vantagem o baixo custo de fabricação, a rapidez de montagem das treliças, a facilidade de transporte e a versatilidade no detalhamento das ponteiras das diagonais. Foi realizado um levantamento bibliográfico nas prescrições de cálculo e demais publicações, nacionais e internacionais, para ligações de estruturas tubulares e encontrou-se um estudo para esse tipo de ligação, mas apenas analisando treliças planas. Para verificar o comportamento da ligação, serão analisados modelos numéricos desenvolvidos com o programa de elementos finitos ANSYS 14.0. Os resultados encontrados com esses modelos serão analisados e comparados com os resultados numéricos encontrados na pesquisa de ligação pinada com chapa em treliças tubulares planares para elaboração de um fator de correção entre os dois tipos de ligação / Abstract: This paper objective is to propose a connection type for tubular steel trusses with circular section, multiplanar and with gusset plate. In these connections the ends of the diagonals are overlapped and joined by a single pin resulting a pinned connection. The position of the gusset plate in the connections implies an eccentricity which results in additional efforts in the structure. The advantage of this connection type is the low manufacturing cost, the fast erection of trusses, the easier transportation and the versatility in the detailing constructive of the diagonals end. Survey in technical books, standards, manuals and scientific articles was made for tubular steel structures connection. In this survey was found a research for a similar type of connection, but in this there were only analysis of planar trusses. Numerical models using the commercial finite element software ANSYS 14.0 will be analyzed to check the connection. The results from these models will be analyzed and compared with numerical results in the bibliographic review about planar truss for preparation of a correction factor between the two types of connection. OBSERVAÇÃOA palavra gusset nas palavras chaves, título em inglês e no abstract devem ser grifadas em itálico / Mestrado / Estruturas e Geotécnica / Mestra em Engenharia Civil

Orientador: João Alberto Venegas Requena / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-14T15:27:42Z (GMT). No. of bitstreams: 1 Vieira_RodrigoCuberos_M.pdf: 3840052 bytes, checksum: b4860daa77b57af17db9c3c0885bb512 (MD5) Previous issue date: 2009 / Resumo: As coberturas metálicas são muito utilizadas em edificações que necessitam de grandes espaços internos livres e possuem um prazo de execução pequeno, como por exemplo, galpões comerciais, industriais e centros de armazenamento e distribuição. Dentre as suas partes constituintes, as terças são responsáveis por uma parcela considerável do peso total da cobertura. Neste trabalho foi desenvolvido um amplo estudo sobre os diversos tipos de terças metálicas utilizadas em estruturas metálicas de médio e grande porte, com vãos de até 40 metros, abordando as terças em perfil laminado e formado a frio, e as terças treliçadas em perfis abertos e tubulares. Foram realizados estudos aprofundados sobre o dimensionamento de terças em perfil laminado e formado a frio, com o desenvolvimento de um programa de verificação e dimensionamento para esses tipos de terças. Também foram realizados estudos sobre o dimensionamento de terças treliçadas planas, também conhecidas como joists, que já têm a sua utilização bastante difundida, e de terças treliçadas tubulares multiplanares, cuja utilização ainda é pequena se comparada com os demais tipos de terças. Com esses estudos, foram feitas análises comparativas para diversos vãos, com as ações comumente utilizadas em estruturas que possuem coberturas metálicas, possibilitando identificar qual o tipo de terça mais adequado para cada situação estudada. Uma análise dos custos das terças também foi realizada, permitindo verificar a viabilidade da utilização das terças treliçadas tubulares em coberturas metálicas, principalmente das terças treliçadas tubulares multiplanares, cuja aplicação ainda é pequena. / Abstract: Steel roof systems are widely used in buildings that require large free internal spaces and small execution times, such as commercial and industrial warehouses and storage and distribution centers. The purlins have a considerable contribution in the roof system total weight composition. In this work was developed a study on the different types of purlins for medium and large spans, up to 40 meters, analyzing the hot-rolled sections, cold-formed sections and trusses with open or hollow sections. Purlin design studies were conducted for hot-rolled and cold-formed sections, with a computational software development for these purlin types. The use of planar trusses as purlins, also called steel joists, is already well known, and its design was studied too, as well as the multi-planar tubular trusses, whose use is still small when compared with the other purlin types. With these studies, a comparative analysis was made for various spans, applying the loads commonly used in steel roof systems, allowing the investigation of the best purlin type for each proposed situation. An analysis of the purlin costs was also performed, allowing to study the feasibility of the tubular trusses use in steel roof systems, especially the multi-planar tubular trusses, whose application is still small. / Mestrado / Estruturas / Mestre em Engenharia Civil

Master of Science / Department of Industrial & Manufacturing Systems Engineering / Shuting Lei / Polyglycolic acid (PGA) is an important polymer in the field of tissue engineering. It has many favorable properties such as biocompatibility, bioabsorbability, high melting point, low solubility in organic solvents, high tensile strength and is used in a variety of medical related applications. Currently there are various methods such felting, stitching, use of binder/adhesive for joining the non woven meshes of PGA polymer in order to make suitable three dimensional scaffolds. The existing methods for joining the non woven meshes of PGA polymer are usually time consuming and not very flexible. Thus there is a need for a better technique that would overcome the drawbacks of the existing methods. Laser welding offers potential advantages such as high welding rates, easy to automate, improved seam and single sided access such that welds can be performed under various layers of fabric. Therefore, the main objective of this research is to conduct a fundamental study on laser welding of non woven PGA scaffold felts. An experimental setup for spot welding is built that would assist in the formation of tubular structures. A factorial design of experiments is used to study the effects of the operating parameters such as laser power, beam diameter, time duration and pressure on the weld quality. The weld quality is assessed in terms of weld strength and weld diameter. Based on the parametric study, a regression analysis is carried out to form correlations between weld quality and the operating parameters, which could be used to select the optimal operating conditions. The successful welds obtained by the laser welding process have no discoloration and are stronger than the tensile strength of the original non woven sheets of PGA biofelt.

The organic anion transporting polypeptide 4c1 (Oatp4c1) was previously identified as a novel uptake transporter predominantly expressed at the basolateral membrane in the rat kidney proximal tubules. Its functional role was suggested to be a vectorial transport partner of an apically-expressed efflux transporter for the efficient translocation of physiological substrates into urine, some of which were suggested to be uremic toxins. In vitro studies in polarized cell lines showed that upon transfection rat Oatp4c1 localizes at the apical membrane. The objectives of this project were to further validate the subcellular localization of Oatp4c1/OATP4C1 in rat and human tissues as well as their localization and function in polarized cells. Using several complementary biochemical, molecular and proteomic methods as well as antibodies amenable to immunohistochemistry, immunofluorescence, and immunoblotting, we investigated the expression pattern of Oatp4c1 in epithelial cell lines and in the rat kidney and mammary gland (MG). Collectively, these data demonstrated that rat Oatp4c1 localized at the apical cell surface of polarized epithelium and primarily in the proximal straight tubules, the S3 segment of proximal tubule, in the juxtamedullary cortex. Drug uptake studies in Oatp4c1-expressing cells demonstrated that Oatp4c1- mediated estrone-3-sulfate (E3S) uptake was ATP-independent and pH-dependent. The increased E3S transport activity at acidic extracellular pH was ascribed to the increased maximum transport rate (Vmax). In addition, E3S transport inhibition by various substrates suggests that Oatp4c1 possesses multiple substrate binding sites. The apical localization of Oatp4c1 in the rat kidney and MG is a novel finding and implies that this transporter protein plays a role in the reabsorption, not vectorial secretion, of its substrates. In addition, the upregulation of Oatp4c1 expression during lactation indicates that it is involved in reuptake of xenobiotic from the milk, resulting in their reduced exposure to the suckling infants, or that it functions as a scavenger system. Further, studies to identify physiological substrates are needed to better understand the significance of Oatp4c1 function in renal and mammary epithelium.

It is well known that a variety of toxicants can cause damage to the renal proximal tubule. However, the early pathogenesis of these deleterious interactions between a toxicant and this region of the nephron remain poorly understood. Thus, the purpose of this research was to attempt to answer three interrelated questions. First, what are the earliest changes in kidney function and structure after administration of tubule toxicants in vivo? Secondly, how do these structural/functional alterations change over time? Finally, are certain indicators of renal "dysfunction" more sensitive then others to the early stages of proximal tubule injury? The basic experimental approach consisted of injecting laboratory animals with a selective proximal tubule toxicant, and then collecting blood and/or urine at several timepoints after dosing; a variety of renal function indicators were evaluated at each of these timepoints. These included blood urea nitrogen (BUN), the glomerular filtration rate (GFR), and the excretion of glucose, protein, salts, glutathione, enzymes, and other endogenous molecules into the urine. At the termination of the exposure period the kidneys were evaluated histopathologically, and were also assayed for levels of specific enzymes and glutathione. Enzyme histochemistry was used to visualize changes in renal enzyme distribution, and protein electrophoretic methods permitted quantification of urinary proteins. These studies showed that specific markers of renal dysfunction were more sensitive to acute proximal tubule injury than other indicators. Specifically, the urinary excretion of proteins and the brush border membrane marker γ-glutamyl transpeptidase (GGT) were the best indicators of proximal tubule injury. Glucosuria, lysozymuria, and glutathionuria were all less sensitive markers, and changes in BUN or GFR were the poorest indicators of acute proximal tubule injury. These results indicated that the brush border membrane is one of the most susceptible regions of the proximal tubule to acute renal injury. Analysis of urinary protein electrophoresis patterns and kidney histopathology confirmed this hypothesis. This research also demonstrated the progression of the toxicant-tubule interaction over time, and showed that both tubule structure and function may be altered within minutes of administering a nephro-toxicant.

The basis for performing a thermo-mechanical staggered coupled heat source analysis of a welding simulation is implemented into LS-DYNA. In this report, three methods for initiating the heat source’s mechanical motion during girth and tubular joint welding are developed and evaluated. The first method is a reformulation of the equations used at Det Norske Veritas, the second is an incorporation of the equations into excel and the third is a standalone third party software. The most efficient of the developed methods turned out to be the software which creates k-files which are implemented into the main k-file using LS-PrePost. All methods have been visually and numerically evaluated using Excel, LS-DYNA and LS-PrePost.

The effect of inorganic electrolytes on the determination of relative permittivity and concentration of water solutions of 1,4 dioxane was studied in this work. The method used was dielectrimetry, and NaCl, KCl, CsCl and LiCl at various concentrations were tested electrolytes. The interfering effect of these electrolytes was found for concentrations above 0.05 mmol l-1. It was also found that the interfering factor is purely the solution conductivity independent on the ion kind. The measurements were carried out with both the planar and the tubular detection cell having the electrodes insulated from the solution. The cell was connected to the differentiator (the voltage is the analytical signal) or multivibrator (the frequency is the analytical signal). A good agreement between experimental results and the modeled calculation for the detector with differentiator was also obtained.

<div>Thin walled structures find wide applications in automotive industry as energy absorption devices. A great deal of research has been conducted to design thin walled structures, where the main objective is to reduce peak crushing forces and increase energy absorption capacity. With the advancement of computers and mathematics, it has been possible to develop 2D patterns which when folded turn into complex 3D structures. This technology can be used to develop patterns for getting structures with desired properties. </div><div>In this study, square origami tubes with folding pattern (Yoshimura pattern) is designed and studied extensively using numerical analysis. An accurate Finite Element Model (FEM) is developed to conduct the numerical analysis. A parametric study was conducted to study the influence of geometric parameters on the mechanical properties like peak crushing force, mean crushing force, load uniformity and maximum intrusion, when subjected to dynamic loading. </div><div>The results from this analysis are studied and various conclusions are drawn. It is found that, when the tube is folded with the pattern having specific dimension, the performance is enhanced significantly, with predictable and stable collapse. It is also found that the stiffness of the module varies with geometrical parameters. With a proper study it is possible to develop origami structures with functionally graded stiffness, the performance of which can be tuned as per requirement, hence, showing promising capabilities as an energy absorption device where progressive collapse from near to end impact end is desired.</div><div><br></div>