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Orientadores: Katia Lucchesi Cavalca Dedini, Euclides de Mesquita Neto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T09:33:08Z (GMT). No. of bitstreams: 1 Ramalho_DeniseAlves_D.pdf: 3277236 bytes, checksum: d90e15781524b19a49afda1e9c94e31d (MD5) Previous issue date: 2010 / Resumo: Nas últimas três décadas houve um desenvolvimento notável em métodos e tópicos de pesquisa a respeito da análise da dinâmica de máquinas rotativas. Um dos tópicos que têm atraído a atenção de pesquisadores é a interação de máquinas rotativas com suas estruturas de suporte. Sabe-se que a dinâmica da estrutura pode exercer um importante papel na resposta do rotor. Mas há um tópico que ainda não recebeu a atenção que deveria. As estruturas de suporte do rotor estão colocadas sobre uma fundação e esta fundação interage com suas vizinhanças e com o solo. A questão da influência da fundação e do solo na resposta do rotor ainda não foi completamente estudada. Tentativas anteriores de descrever o comportamento do sistema rotor-fundação-solo são limitadas a modelos muito simples de solo. O objetivo deste trabalho é estudar a influência do solo no comportamento de máquinas rotativas. Isto foi feito através de um modelo rotor-mancais-fundação-solo. Obtém-se a resposta desbalanceada de um rotor Laval bidimensional, desprezando-se o efeito giroscópico. Variou-se o tipo de solo, considerando um semi-espaço e um solo do tipo camada sobre base rígida, sendo este último um solo com um aumento repentino de rigidez a uma determinada profundidade. Em cada um destes solos, houve uma variação do amortecimento interno. Além disso, para o solo do tipo camada sobre base rígida, houve uma variação da espessura dessa camada. Estes solos são caracterizados pela densidade, coeficiente de Poisson e módulo de cisalhamento, e são considerados viscoelásticos. Os modelos destes solos, utilizados neste trabalho, são modelos numéricos e foram obtidos utilizando o método dos elementos de contorno / Abstract: In the last three decades there has been a notable development of methods and research topics regarding the analysis of the dynamics of rotating machines. One topic that has attracted researcher's attention is the interaction of rotor - foundation interaction. It is well known that the dynamics of the structure play an important hole in the rotor response. However, one topic has still not received the attention it should have. The rotor support structure was placed on a foundation, and the foundation interacted with its neighbourwood and with the soil. The issue of the influence of both the foundation and the soil on the rotor response has not yet been completely studied. Previous attempts to describe the behaviour of the system rotor-foundationsoil were limited to very simple models of the soil. The objective of this work is to study the influence of the soil on the behaviour of rotating machines. This study was carried out by using a rotor-bearing-foundation-soil model. An unbalanced response of a bidimentional Laval rotor isobtained. The gyroscopic effect was neglected. The type of soil was varied, considering a halfspace and a stratified soil. The last soil had a sadden increase in the stiffness at a certain depth. In each one of these soils there has been a variation in the internal damping. Moreover, the thickness of the stratified soil has varied. These soils are caracterized by the density, Poisson's cofficient and shear modulus, and they are considered visco-elastic. In this work, the soil models are numerical and they were obtained by using the boundary element method / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

Settlement-Induced Bending Moments (SIBM) are an important design condition that must be considered whenever battered piles are placed in settling soils. The objective of this research was to investigate various parameters which can affect SIBM in battered piles within a levee embankment. The results from the current study were compared and verified against those obtained from centrifuge testing and alternative numerical simulations. A series of centrifuge testing as well as finite difference numerical simulations in Fast Langrangian Analysis of Continua (FLAC) were conducted. Different parameters which may affect the bending moments were investigated including pile connection fixity, batter, and stiffness of the pile as well as the magnitude of settlement. The simulations show that these parameters can have large impacts on the magnitude and location of the bending moments. Findings of this research can be used to validate or identify the need for adjustment of the current modeling/design approach.

The thesis is devoted to analysing of flexible buried arch structures. Modelling of the flexible concrete arch is carried out via a nonlinear finite element model that accounts for soil constitutive relations, soil-structure interactions, sequential construction stages and soil compaction. Advanced FE-model was verified by measurement obtained by full-scale field testing of two buried arches. Mathematical optimization methods of genetic algorithms and Levenberg-Marquardt method are applied to already calibrated complex computational models in order to reduce bending and associated flexural stresses in the concrete section of buried arch. Centre line of the arch is parameterized by cubic Bezier curve to reach interpolation of thrust line. Optimization technique is applied with extensive parametrical study which shows the optimal shapes for buried arches of various span/rise ratios, backfill depths and foundation soil types. For practical application are given coordinates of Bézier curve control polygons of particular resulting shape. Subsequently is applied optimization method for a theoretical reduction of tensile stresses obtained by shape optimization of previously verified numerical model of buried arch. Comparisons of earth pressure, bending moment axial force and deflection of flexible structure during sequential construction of different span/raise ratios of buried arches are presented. The behaviour of flexible buried arch with effect of local traffic load model LM1 has been analysed via 3D finite elements model with respect to different depth of backfill above crown.