Pipe jacking, has seen a rise in popularity, particularly in urban areas where infrastructure does not permit cut-and-cover methods. As pipe jacking has becomes more commonplace, engineers are pushing the limits of the technology more and more by designing longer drives in more difficult ground conditions. Lubrication is essential to reduce the frictional resistance generated at the pipe-soil interface. Even though lubrication is widely utilized, there is not a clear understanding of the conditions required to obtain the full benefit of lubrication. This dissertation focuses on bentonite slurry characteristics and interface behavior under different lubricating conditions with the goal to further the understanding of the mechanisms responsible for the large friction reductions observed in the field. An interface shear device capable of measuring interface behavior on pipe surfaces was used to perform tests under two lubricating conditions. Pipes were sheared against a mixture of sand and slurry and the effect of the slurry was quantified. In another series of tests, slurry was injected at the pipe-soil interface. An axisymmetric interface shear device was developed to further investigate the lubrication mechanism associated with injection of slurry into sand. The device was designed to inject slurry through injection ports built into a shaft displaced within a sealed sand-filled chamber. A series of tests were performed on dry sand as well as sand where water or slurry was injected during shearing. The effect of sand type and viscosity are also investigated. Findings from the experimental studies are related back to full-scale behavior with the objective of assessing the lubrication methods and their effectiveness. A rational procedure for predicting non-lubricated and lubricated jacking forces is proposed to optimize design and serve as a framework for evaluating jacking forces in the field.

Serving as critical gateways for international trade, seaports are pivotal elements in transportation networks. Any disruption in the activities of port infrastructures may lead to significant losses from secondary economic effects, and can hamper the response and recovery efforts following a natural disaster. Particularly poignant examples which revealed the significance of port operations were the 1995 Kobe earthquake and 2010 Haiti earthquake in which liquefaction and lateral spreading of embankments imposed severe damage to both structural and non-structural components of ports. Since container wharf structures are responsible for loading and unloading of cargo, it is essential to understand the performance of these structures during earthquakes. Although previous studies have provided insight into some aspects of the seismic response of wharves, limitations in the modeling of wharf structures and the surrounding soil media have constrained the understanding of various features of the wharf response. This research provides new insights into the seismic behavior of wharves by using new and advanced structure and soil modeling procedures to carry out two and three-dimensional seismic analyses of a pile-supported marginal wharf structure in liquefiable soils. Furthermore, this research investigates the interaction between cranes and wharves and closely assesses the role of wharf-crane interaction on the response of each of these systems. For this purpose, the specific effect of wharf-crane interaction is studied by incorporating advanced models of the crane with sliding/uplift base conditions. To reduce the computational time required for three-dimensional nonlinear dynamic analysis of the wharf in order to be applicable for probabilistic seismic demand analysis, a simplified wharf model and an analysis technique are introduced and verified. In the next step probabilistic seismic demand models (PSDMs) are generated by imposing the wharf models to a suit of ground deformations of the soil embankment and pore water pressure generated for this study through free-field analysis. Convolving PSDMs and the limit states, a set of fragility curves are developed for critical wharf components whose damage induces a disruption in the normal operation of ports. The developed fragility curves provide decision makers with essential tools for maximizing investment in wharf retrofit and fill a major gap in seismic risk assessment of seaports which can be used to assess the regional impact of the damage to wharves during a natural hazard event.

[Truncated abstract] Three-legged mobile jack-up rigs supported on spudcan foundations are used to perform most offshore drilling in shallow to moderate water depths, and are now capable of operating in water depths up to 130 m. With the gradual move towards heavier rigs in deeper water, and continuing high accident rates during preloading of the spudcan foundations, appraisal of the performance and safety of jack-up rigs has become increasingly important. A crucial aspect of this is to improve understanding of the mechanisms of soil flow around spudcan foundations undergoing continuous large penetration, and to provide accurate estimates of spudcan penetration resistance, avoiding excessive conservatism. Spudcan foundations undergo progressive penetration during preloading, contrasting with onshore practice where a footing is placed at the base of a pre-excavated hole or trench. However, spudcan penetration is generally assessed within the framework used for onshore foundations, considering the bearing resistance of spudcans pre-placed at different depths within the soil profile. The lack of accurate design approaches that take proper account of the nature of spudcan continuous penetration, which is particularly important in layered soil profiles, is an important factor in the high rate of accidents. ... It was found that when a spudcan penetrated into single layer clay, there were three distinct penetration mechanisms: during initial penetration, soil flow extended upwards to the surface leading to surface heave and formation of a cavity above the spudcan; with further penetration, soil began to flow back gradually onto the top of the spudcan; during deep penetration, soil back-flow continued to occur while the initial cavity remained unchanged. For spudcan penetration in stiff-over-soft clay, four interesting aspects of the soil flow mechanisms were identified: (a) vertically downward motion of the soil and consequent deformation of the layer interface; (b) trapping of the stronger material beneath the spudcan, with this material being carried down into the underlying soft layer; (c) delayed back-flow of soil around the spudcan into the cavity formed above the spudcan; (d) eventual localised flow around the embedded spudcan, surrounded by strong soil. At some stage during continuous spudcan penetration, the soil starts to flow back into the cavity above the spudcan. The resulting back-flow provides a seal above the penetrating spudcan and limits the cavity depth. It was shown that the current offshore design guidelines are based on the wrong criterion for when back-flow occurs. New design charts with robust expressions were developed to estimate the point of back-flow and hence the cavity depth above the installed spudcan. Load-penetration responses were presented in terms of normalised soil properties and geometry factors for both single layer and two-layer clay profiles, taking full account of the observed flow mechanisms. Further, guidelines were suggested to evaluate the likelihood and severity of spudcan punch-through failure in layered clays. Finally, the effect of strain-rate and strain-softening was examined, in an attempt to model real soil behaviour more closely. Adjustment factors were proposed to modify the design approaches developed on the basis of ideal elastic-perfectly plastic soil behaviour.

This thesis describes a numerical investigation of shallow circular foundations resting on various types of soil, mainly siliceous and calcareous sands. An elasto-plastic constitutive model, namely the MIT-S1 model (Pestana, 1994), which can predict the rate independent behaviour of different types of soils ranging through uncemented sands, silts and clays, is used to simulating the compression, drained triaxial shear and shallow circular foundation responses. It is found that this model provides a reasonable fit to measured behaviour, particularly for highly compressible calcareous sands, because of the superior modelling of the volumetric compression. The features of the MIT-S1 model have been used to investigate the effects of density, stress level (or foundation size), inherent anisotropy and material type on the response of shallow foundations. It was found that the MIT-S1 model is able to distinguish responses on dilatant siliceous and compressible calcareous sands by relatively minor adjustment of the model parameters. Kinematic mechanisms extracted from finite element calculations show different deformation patterns typical for these sands, with a bulb of compressed material and punching shear for calcareous sand, and a classical rupture failure pattern accompanied by surface heave for siliceous sand. Moreover, it was observed that the classical failure pattern transforms gradually to a punching shear failure pattern as the foundation size increases. From this evidence, a dimensional transition between these failure mechanisms can be defined, referred to as the critical size. The critical size is also the limiting foundation size to apply conventional bearing capacity analyses. Alternative approaches are needed, focusing mainly on the soil compressibility, for shallow foundations greater than the critical size. Two approaches, 1-D compression and bearing modulus analyses, have been proposed for those foundation conditions. From the validations, the former is applicable for extremely large foundations, very loose soil conditions and highly compressible calcareous materials, while the latter is suitable for moderate levels of compressibility or foundation size. It is suggested that appropriate assessment of compression features is of great importance for shallow foundation analysis on sand.

Le terme variabilité spatiale des mouvements sismiques (SVGM en anglais pour Spatial Variability of Ground Motion) désigne les différences entre deux mesures du mouvement du sol effectuées à différents endroits, généralement en surface. La modélisation de SVGM ainsi que son effet sur la réponse dynamique des barrages est nécessaire pour l'intégration du phénomène dans les codes parasismiques. L'étude actuelle présente une mesure et une enquête approfondie sur SVGM à l'interface barrage voûte - fondation rocher. Des mesures in situ sont utilisées pour sa quantification et des simulations numériques pour la compréhension plus approfondie des phénomènes physiques qui contribuent à SVGM notamment à l'interface, c-à-d la topographie de la voûte et l'interaction sol-structure. Les données in situ provient d'une campagne sismologique qui a eu lieu sur et autour le barrage voûte du Saint Guérin pendant six mois. Le sous-ensemble d'événements consiste des événements de faible à moyenne magnitude, locaux et régionaux. Ainsi, des analyses linéaires sont permises. Tout d'abord, l'analyse dynamique du barrage voûte est réalisée; les fréquences de vibration, le coefficient d'amortissement et l'amplification de crête sont estimées profitant des mesures continues de bruit ambiant et des enregistrements sismiques. Ensuite, le SVGM est quantifiée au moyen de la phase et de la variabilité d'amplitude en utilisant des estimations de cohérence et de l'écart type de la différence des amplitudes des spectres de Fourier respectivement. Forte variabilité est observée à la fois en phase et en amplitude à l'interface de barrage-fondation rocher. Une fois que les estimateurs de la variabilité sont obtenus à partir des données, les modèles paramétriques existants sont comparés avec eux. Accentuation est mis sur deux observations: 1) les mouvements sismiques au champ libre semblent être légèrement moins variable par rapport aux mouvements à l'interface barrage-fondation rocher et 2) à l'interface barrage-fondation rocher, il y a une variabilité plus forte autour des fréquences de vibration du barrage. Ces observations suggèrent que la présence de la structure ainsi que la topographie du canyon augmentent SVGM. Cette hausse semble cependant être faible étant donné que les observations sont montés par des modèles paramétriques satisfaisants basés sur des données provenant de réseaux sismiques plates (sans topographie et structure). Des simulations numériques dans le code SPECFEM3D, basé sur les éléments spectraux, sont utilisées pour étudier plus profondément les observations in situ par le découplage des différentes causes de SVGM et évaluer l'impact de chacune. Une étude paramétrique en utilisant une topographie du canyon simplifié tente d'identifier l'effet de la topographie du canyon local sur SVGM tandis qu'un modèle géométrique précis du barrage voûte à Saint Guérin et sa topographie du canyon nous donne une idée plus précise sur l'impact de l'interaction barrage-fondation rocher sur SVGM. Les résultats de cette recherche devraient contribuer à l'amélioration de notre compréhension de SVGM à l'interface barrage-fondation rocher et de proposer des modèles de variabilité utilisés dans la conception de barrages voûtes. / Spatial variability of seismic ground motions (SVGM) denotes the differences between two time histories of the ground motion recorded at different locations, generally at the ground surface. The modeling of SVGM and the understanding of its influence on the dam's response are necessary so as design codes start to incorporate its effects in their provisions. This study presents a measure and a profound investigation of SVGM at the dam-foundation rock interface of an arch dam. In-situ measurements are used to quantify SVGM and numerical simulations to deeper understand the particular physical phenomena that contribute to SVGM at the interface, i.e. local canyon topography and rock-structure interaction. The in-situ data comes from a seismological experimental campaign that has taken place on and around Saint Guérin arch dam over the period of six months. The campaign was held in the framework of the present thesis. The subset of events consists of low to moderate magnitude local and regional earthquakes. Thus, analysis is allowed in the linear range. Firstly, dynamic analysis of the arch dam is conducted; the frequencies of vibration, the damping coefficient and the crest amplification are estimated based on ambient noise and seismic records. Then, SVGM is quantified by means of phase and amplitude variability using coherency estimates and standard deviation of difference of Fourier amplitudes respectively. High variability is observed both in phase and amplitude at the dam-foundation rock interface. Once the estimators of variability are obtained from the data, parametric models are fitted to them. Focus is given on two observations : 1) the ground motions in the free field appear to be slightly less variable with respect to the motions at the dam-foundation rock interface and 2) at the dam-foundation rock interface, there is higher variability around the frequencies of vibration of the dam. These observations suggest that the presence of the structure along with the canyon topography increase SVGM. This increase though seems to be small given that the observations are satisfactory fitted by parametric models based on data coming from flat seismic arrays. Numerical simulations in the SPECFEM3D code, based on the spectral element method are used to deeper investigate the in-situ observations by decoupling the various causes of SVGM and evaluating the impact of each one. A parametric study using a simplified canyon topography attempts to identify the effect of local canyon topography on SVGM while a geometrically accurate model of the Saint Guérin arch dam and its canyon topography gives us a better insight on the dam-foundation rock interaction impact on SVGM. Although both features are found to increase SVGM, their impact remains secondary. The findings of the present research are expected to contribute in enhancing our understanding of SVGM at the dam-foundation rock interface and proposing variability models used in arch dams' design.

Ce travail s'inscrit dans la continuité des travaux de recherche menés au laboratoire Géoressources (Ecole des Mines de Nancy) et à l'INERIS depuis plusieurs années. Il concerne l’évaluation de la vulnérabilité des ouvrages situés dans des zones de mouvement de terrains d’origine naturelle ou anthropique. L’objectif de la thèse est de développer un modèle analytique permettant l’évaluation du tassement différentiel d’un ouvrage soumis à un mouvement de terrain et de calculer le taux de transmission de ces mouvements en fonction de la rigidité relative de l’ouvrage. Le modèle d’interaction sol-structure développé, tient compte de l’influence des contraintes de cisaillement dans le bâti et le terrain et d’un comportement poste-rupture du sol grâce à l’introduction d’une limite de plasticité. Le sol a été modélisé par les éléments de Pasternak afin de prendre en compte l'influence des déformations de cisaillement dans le sol, alors que le bâtiment est modélisé par la poutre d'Euler-Bernoulli et par la poutre de Timoshenko. L’existence potentielle d’un vide (décollement) sous le bâtiment a également été prise en compte dans le modèle analytique développé. Le taux de transmission des mouvements en champ libre du terrain au bâtiment a été calculé et présenté en fonction de la rigidité relative en flexion du bâtiment par rapport au terrain. Pour valider le développement entrepris, les résultats du modèle analytique ont été comparés aux résultats de modèles existants, analytiques, numériques et expérimentaux développés principalement par l'Université de Cambridge. Les résultats obtenus sont très satisfaisants et permettant de confirmer la robustesse du modèle analytique développé / This work is a continuation of the research work conducted in the Géoressources Laboratory and INERIS since several years. It concerns the assessment of the vulnerability of masonry structures influenced by natural or induced ground movements. The origins of the movement are may be, mining subsidence, tunneling, and shrinkage-swelling of clayed ground. The objective of the thesis is to develop an analytical model to evaluate the differential settlement of a structure in relation to the free field ground movement and given a set of phenomena: soil-structure interaction, influence of shear deformations in the structure and the ground, influence of non- linearities induced by the ground yielding. The soil was modeled by Pasternak elements to take into account the influence of shear deformations in the soil, while the building is modeled by the Euler-Bernoulli beam and by the beam of Timoshenko. The possibility of having a gap under the building was also taken into account. The deflection transmission ratio is then calculated and plotted according to are lative stiffness ratio which depend on both the structure and the soil stiffness A numerical model is also developed and results are compared with those of the analytical model. Other results of several numerical and experimental models principally developed at the University of Cambridge are also used for this comparison. Results show significant consistence between all these results. This demonstrates the significance of the analytical soil-structure model developed in this thesis

La concentration de plus en plus importante de la population dans les milieux urbains exposés à une forte sismicité peut générer de plus en plus de dommages et de pertes. La réponse sismique en milieu urbain dépend des effets du site (direct amplification et non-linéarité du sol) et du couplage entre le sol et les structures (interaction sol-structure et site-ville). Par conséquent, la compréhension de la sismologie urbaine, c'est-à-dire le mouvement du sol intégrant l'environnement urbain, est critique pour réduire les dommages. Cela passe par la prédiction du mouvement du sol dans le milieu urbain, ingrédient fondamental à l'évaluation de l'aléa sismique. La prise en compte de l'amplification provoquée par la présence de sédiments est largement étudiée. Au contraire, la réponse non-linéarité du sol et du couplage entre le sol et la structure est rarement intégrée à la prédiction du mouvement du sol. A cause de leur complexité, ces problèmes ont toujours été abordés séparément. Dans ce contexte, cette thèse analyse la réponse non-linéaire du système sol-structure en intégrant la non-linéarité du sol et de l'interaction sol-structure. Deux travaux expérimentaux ont été conduits, avec comme but de proposer un proxy, rendant compte de la non-linéarité du sol. Le premier est l'essai en centrifugeuse qui reproduit à échelle réduite la réponse du sol et des structures. L'état de contrainte et de déformation est conservé en appliquant une accélération artificielle au modèle. Cet essai a été effectué à IFSTTAR Nantes dans le cadre de l'ANR ARVISE. Différentes configurations ont été testées, avec et sans bâtiments, sous différents niveaux de sollicitation, pour analyser la réponse du sol et des structures. Le deuxième utilise les enregistrements des réseaux accélérométriques verticaux de deux sites tests californiens : Garner Valley Downhole Arrat (GVDA) et Wildlife Liquefaction Array (WLA), gérés tout deux par l'Université de Californie, Santa Barbara (UCSB), Etats-Unis. La réponse in-situ est importante car elle décrit le comportement réel du site. Plusieurs informations décrivant les conditions de sites sont disponibles et les séismes enregistrés ont permis de tester plusieurs niveaux de déformations pour reconstruire la réponse globale de chaque site. De plus, le site GVDA est équipé d'une structure Soil-Foundation-Structure-Interaction (SFSI) qui a comme objectif d'étudier les problèmes d'interaction sol-structure. Dans les deux expériences, grace au réseau accélérométrique vertical dans le sol et la structure, on peut appliquer la méthode de propagation d'ondes 1D pour extraire la réponse de ces systèmes. Les ondes sont considérées comme des ondes SH qui se propage horizontalement dans une couche 1D. La méthode interférométrie sismique par déconvolution est appliquée pour extraire l'Impulse Response Function (IRF) du système 1D. On analyse ainsi la variation de Vs en fonction de la solliictation et à différente position dans le sol ainsi que la variation des éléments expliquant la réponse dynamique du système sol-structure. On propose au final un proxy de déformation permettant de rendre compte mais aussi de prédire la nonlinéarité des sols en fonction des niveaux sismiques subits. / The concentration of population in urban areas in seismic-prone regions can generate more and more damages and losses. Seismic response in urban areas depends on site effects (direct amplification and nonlinearity of the soil) and the coupling between the soil and structures (soil-structure and site-city interaction). Therefore, the understanding of urban seismology, that is the ground motion incorporating the urban environment, is critical to reduce the damage. This requires the prediction of ground motion in urban areas, a fundamental element in the evaluation of the seismic hazard. Taking into account the amplification caused by the presence of sediment has been widely studied. However, the non-linearity of the soil and the coupling between the ground and the structure is seldom integrated to the prediction of the ground motion. Because of their complexity, these problems have been addressed separately. In this context, this dissertation analyzes the non-linear response of the soil-structure by integrating the non-linearity of the soil and the soil-structure interaction. Two experimental studies were performed, with the aim of providing a proxy that reflects the non-linearity of the soil. The first is the centrifuge test that reproduces the response of soil and structures at reduced scale. The state of stress and strain is conserved by applying an artificial acceleration model. This test was performed at IFSTTAR Nantes in the framework of the ANR ARVISE. Different configurations were tested with and without buildings, under different stress levels, to analyze the response of the soil and structures. The second uses the vertical accelerometric networks of two sites in California: Garner Valley Downhole (GVDA) and the Wildlife Liquefaction Array (WLA), both managed by the University of California, Santa Barbara (UCSB), USA. In-situ response is important since it describes the actual behavior of the site. Information describing the conditions of sites is widely available and the earthquakes recorded were used to test several levels of shaking to reconstruct the overall response of each site. In addition, the GVDA site is equipped with a Soil-Foundation-Structure-Interaction structure (SFSI) which aims to study the problems of soil-structure interaction. In both experiments, thanks to the vertical accelerometer network in the ground and the structure we are able to apply the 1D wave propagation method to extract the response of these systems. The waves are considered as an SH wave which propagates in a 1D horizontal layer. Seismic interferometry by deconvolution method is applied to extract the Impulse Response Function (IRF) of the 1D system. Thus the analysis of the variation in function of elastic properties of the soil and the structure is done under several magnitude of shaking, including variation in depth and the elements of the total response of the structure including the soil-structure interaction. At the end, a deformation proxy to evaluate and also to predict the nonlinear response of the soil, the structure and the soil-structure interaction is proposed.

Neste trabalho foi desenvolvida uma formulação alternativa para o acoplamento entre o método dos elementos de contorno (MEC) e o método dos elementos finitos (MEF) para análise não linear geométrica de estruturas reticuladas ligadas a meios contínuos bidimensionais heterogêneos, aplicado a problemas de interação solo-estrutura. O solo foi considerado com comportamento elástico linear e modelado via MEC por meio de uma formulação alternativa à clássica técnica de sub-região permitindo a consideração de múltiplas inclusões mais ou menos rígidas do que o material padrão e de linhas de carga internas aos domínios. Este código foi então acoplado ao programa AcadFrame, baseado no MEF posicional para análise não linear geométrica de pórticos com consideração de cinemática exata. O acoplamento numérico foi realizado por meio de uma formulação algébrica onde a matriz de rigidez do solo e a força de contato são condensadas e somadas à matriz e ao vetor de forças internas da estrutura a cada iteração no processo de Newton-Raphson. Em ambos os programas foi utilizada uma generalização do grau de aproximação dos elementos através dos polinômios de Lagrange, o que permite a utilização de elementos curvos de alta ordem. Foi utilizada ainda a técnica dos mínimos quadrados para reduzir as oscilações de forças de superfície no contato. Os resultados obtidos de forma geral são bastante satisfatórios e comprovam a eficiência da formulação. O trabalho permite a análise de problemas de edificações apoiadas sobre solos estratificados com múltiplas inclusões e linhas de carga. Permite tanto a análise de elementos apoiados diretamente sobre o solo (sapatas, radies) quanto de elementos internos e em qualquer direção, como no caso de estacas verticais ou inclinadas. Pode-se inclusive considerar as estacas passando por diferentes camadas de solo. A aplicação pode ser estendida ainda a outros problemas elásticos, acoplamento entre peças mecânicas e análise de materiais compostos. / This work presents an alternative coupling of the boundary element method (BEM) and the finite element method (FEM) to create a computer program for non linear geometric analysis of frames coupled to continuous domains, applied to soil-structure interaction. A linear elastic behavior is considered for the soil, modeled by BEM. An alternative formulation is adopted for the classic sub-region technique, allowing the consideration of multiple inclusions and load lines inside the soil domain. The BEM computational code is coupled to the AcadFrame software, based on positional FEM for non linear geometric analysis of frames, considering exact kinematics. The numerical coupling is made by an algebraic formulation where the soil stiffness matrix and contact forces are condensed and added to the structure matrix and internal forces for each iteration on Newton-Raphson process. On both programs it is adopted a generalization of the element degree assuming the Lagrange polynomials, which allows the use of curved high order elements. It was also implemented the least square method in order to obtains better and smoother results of surface forces in the contact interface. The obtained results are satisfactory and prove the formulation efficiency. The program allows the analysis of buildings supported by layered soils with multiples inclusions and load lines. It considers directly supported elements over the soil (footing foundations, radies) and internal elements in any direction, like vertical and diagonal piles. It can also consider piles going through different layers of the soil. This formulation can be applied to other elastic problems like coupling between mechanic pieces and composite material analysis.

Made available in DSpace on 2015-05-08T14:59:48Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 7220631 bytes, checksum: d36ace240b1aa4b1c66a0ca9ae99326d (MD5) Previous issue date: 2012-10-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This paper describes elastic, static and dynamic analysis of frames using the Boundary Element Method (BEM). The superstructure is modeled for two frame structure cases (that is, plane frame and space frame) and algebraic specific representations are developed for these purposes. According to the specific cases, bending effects (Euler- Bernoulli or Timoshenko models), torsional effects (under Saint Venant assumptions) are properly operated as well as the explicit forms of displacements and efforts influence matrices and the body force vector. Special attention is paid to the problem of static soil-structure interaction. In this case the superstructure (space frame) is modeled by BEM and the soil (assumed as semiinfinite elastic solid) is represented by integral equations and algebraically systematized in BEM fashion as well. Then, the superstructure and soil algebraic systems are coupled in order to allow the soil-structure interaction analysis. Open section thin-walled beams under Vlasov torsional-flexure assumptions receive also special attention, so that a direct BEM formulation for static and vibration analysis is established. Hence, here it is propposed integral equations, fundamental solution and algebraic representations which incorporate all secondary fields (forces, moments and bimoment) and primary fields (displacements, rotations and warping). For vibration case, both integral and algebraic equations are deduced for bi-coupled problems ( monosymmetric cross-section) and triply-coupled problems (nonsymmetric cross-sections). / Neste trabalho são descritas análises elásticas (estática e vibratória) de pórticos, utilizando o Método dos Elementos de Contorno (MEC). A superestrutura é modelada para duas famílias de estruturas reticuladas (pórtico plano, pórtico espacial) e representações algébricas específicas são desenvolvidos para esse fim. Nos casos pertinentes, os efeitos de flexão (segundo as teorias de Euler-Bernoulli e Timoshenko), de torção (segundo as hipóteses de Saint Venant), são devidamente explorados assim como as formas explícitas das matrizes de influência de deslocamentos, de esforços e o vetor de forças de volume. Um enfoque especial é dado para o problema de interação solo-estrutura em regime estático. Nesse caso a superestrutura (pórtico espacial) é modelada pelo MEC e o solo (admitido como um sólido elástico semi-infinito) é representado por equações integrais e sistematizado algebricamente, também, pelo MEC. Então, os sistemas algébricos da superestrutura e do solo são compatibilizados permitindo assim a análise da interação soloestrutura. As barras de seção abertas de paredes finas incorporando o modelo de flexo-torção de Vlasov também recebem uma atenção especial, de forma que uma formulação direta do MEC para a análise estática e vibratória é estabelecida. Assim, aqui são propostas as equações integrais, soluções fundamentais e representações algébricas, que incorporam todos os campos secundários (forças, momentos e bi-momentos) e os campos primários (deslocamentos, rotações, empenamentos). No caso do problema de vibração, as representações integrais e algébricas são deduzidas para os problemas bi-acoplados (seções monossimétricas) e tri-acoplados (seções não-simétricas).

Made available in DSpace on 2015-05-08T15:00:09Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3383903 bytes, checksum: 0f620c6e964fe188ec48ca2d255558c8 (MD5) Previous issue date: 2010-10-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work a static and dynamic elastic analyses of frame structures using the finite element method (FEM) is described. The superstructure is modeled employing six sets of frame structures (plane truss, space truss, plane frame, grilled, space frame and space frame stiffened by shear cores) and specific finite elements are developed for these purposes. According to the specific case, bending effects (Euler-Bernoulli or Timoshenko models), torsional effects (under Saint Venant or Vlasov assumptions) are properly operated and the explicit forms of stiffness and mass matrices and equivalent nodal vector are presented. Special attention is paid to the static soil-structure interaction problem. In this case the superstructure (standard space frame) is modeled by FEM, whereas the soil is assumed to be an elastic half-space and modeled by the boundary element method (BEM). Finally the algebraic systems from both methods are coupled in order to allow the soil-structure interaction analysis. Another focus of this study is to develop a simulation environment (called SAPROMS NET) incorporating mainly the preprocessing and processing steps and both are implemented in object-oriented language Java. Some numerical examples are presented, as well as details of the simulation environment. / Neste trabalho são descritas análises estática e dinâmica em regime elástico de estruturas reticuladas utilizando o método dos elementos finitos (MEF). A superestrutura é modelada para seis famílias de estruturas reticuladas (treliça plana, treliça espacial, pórtico plano, grelha, pórtico espacial e pórtico espacial enrijecido com núcleo estrutural) e elementos finitos específicos são desenvolvidos para esse fim. Nos casos pertinentes, os efeitos de flexão (segundo as teorias de Euler-Bernoulli e Timoshenko), de torção (segundo as hipóteses de Saint Venant e Vlasov), são devidamente explorados e as formas explícitas das matrizes de rigidez, de massa e vetor nodal equivalente são apresentadas. Um enfoque especial é dado para o problema de interação solo-estrutura em regime estático. Nesse caso a superestrutura, que pode ser associada ao pórtico espacial sem enrijemento por núcleo estrutural, é modelada pelo MEF e o solo (admitido ser um sólido elástico semi-infinito) é representado por equações integrais compostas e sistematizado algebricamente pelo método dos elementos de contorno (MEC). E por fim, os sistemas algébricos do MEF e do MEC são compatibilizados permitindo assim a análise da interação solo-estrutura. Outro enfoque do trabalho é o desenvolvimento de um ambiente de simulação (denominado SAPROMS NET) voltado, principalmente, para as etapas de pré-processamento e processamento. Essas são implementadas na linguagem orientada a objetos Java. Alguns exemplos numéricos são apresentados, assim como o detalhamento do ambiente de simulação.