Le comportement des structures en béton armé peut s’avérer extrêmement complexe en cas de dépassement de la limite de fissuration du béton. Le caractère composite du béton armé doit être représenté finement. Pour la simulation des structures industrielles, les modèles numériques employés supposent une relation parfaite entre le béton et les armatures qui non seulement ne prennent pas en compte la complexité de la relation entre les deux matériaux mais aussi ne permet pas de présenter finement les caractéristiques de la fissuration étant directement liée à celle des aciers. Dans la littérature, plusieurs méthodes numériques sont proposées pour étudier finement les caractéristiques de la liaison acier-béton, mais toutes ces méthodes posent des difficultés pour les calculs de structures complexes en 3D. En partant des résultats obtenus dans le cadre de la thèse de Torre-Casanova (2012), une nouvelle formation d’un modèle de liaison acier-béton a été développée pour améliorer les performances et la représentativité (comportement cyclique). Ce nouveau modèle a été validé sur un tirant par comparaison avec une solution analytique et des résultats expérimentaux et également testé à l’échelle structurelle pour simuler le comportement d’un voile en cisaillement. Compte tenu de la difficulté pour caractériser numériquement l’ouverture de fissure en cas de fissuration complexe, une nouvelle méthode de post-traitement a également été développée. Finalement, le développement du comportement cyclique de la loi d’adhérence avec enveloppe non-réduite est intégré dans le modèle de liaison acier-béton pour prendre en compte l’irréversibilité du glissement et le boucle d’hystérésis lors du chargement en charge-décharge ou du chargement cyclique. L’application sur un tirant et sur un voile en cisaillement est également effectuée afin d’investiguer le comportement global et local. / Reinforced concrete structure behavior can be extremely complex in the case of exceeding the cracking threshold. The composite characteristics of reinforced concrete structure should be finely presented. In order to compute the industrial structures, a perfect relation hypothesis between steel and concrete is supposed in which not only the complex phenomenon of the two-material relation is not taken into account, but it is also unable to predict the crack characteristics, which is directly linked to the steel. In literature, several numerical methods are proposed in order to finely study the concrete-steel bond behavior, but these methods give many difficulties in computing complex structures in 3D. With the results obtained in the thesis framework of Torre-Casanova (2012), the new concrete-steel bond model has been developed to improve performances (iteration numbers and computational time) and the representation (cyclic behavior) of the initial one. The new model has been verified with analytical solution of steel-concrete tie and validated with the experimental results and equally tested with the structural scale to compute the shear wall behavior. Because of the numerical difficulty in post-processing the crack opening in the complex crack formation, a new crack opening method is also developed. Finally, the cyclic behavior of the bond law with the non-reduced envelope is adopted and integrated in the new bond model in order to take into account the slip irreversibility and the hysteresis during the cyclic load. The application of the model is carried out on a steel-concrete tie and a shear-wall.

Un évènement Natech est un accident TECHnologique provoqué par l’impact d’un aléa NAturel sur une installation industrielle. Cet accident peut porter atteinte à l’extérieur de l’emprise du site, aux personnes, aux biens ou à l’environnement. L’objectif de ce travail est de mettre au point une méthodologie pour l’analyse et la prévention du risque d’accidents technologiques induits par l’inondation (Natech inondation) d’un site industriel. La méthodologie repose, dans un premier temps, sur une étude des Retours d’Expériences. Il a été identifié que les accidents Natech sont imputables à un rejet de matières dangereuses sur des équipements dits critiques endommagés directement ou indirectement par les eaux d’inondation. Les rejets de matières dangereuses vont amener à trois types d’accidents (incendie, pollution, explosion). Dans un deuxième temps, la méthode MADS-MOSAR a été adaptée à l’application aux accidents Natech inondation. L’analyse a abouti à cinq scénarios génériques d’accident Natech inondation sous forme de cinq nœuds papillons. Une soixantaine de Mesures de Maîtrise de Risque de prévention et de protection ont été identifiées. La validation de la complétude et de la plausibilité des nœuds papillons génériques est effectuée, d’une part, à l’échelle du secteur d’activité de traitement de surface et, d’autre part, à l’échelle spécifique d’établissements industriels. Ce travail a abouti à un outil de diagnostic de la vulnérabilité d’une installation industrielle aux accidents Natech inondation, accompagné d’un catalogue de MMR. Enfin, ce diagnostic a été appliqué sur un site industriel afin d’évaluer son mode opératoire et de l’enrichir par l’expérimentation. / A Natech accident is the impact of a NAtural event on an industrial plant (such as an ICPE- Classified Installation for the Environmental Protection). The impact can trigger a TECHnological accident, damaging the vicinity of the industrial facility (inhabitants, their properties and the environment). The final objective of this work is to develop a risk analysis methodology for the prevention of technological accidents triggered by flooding of industrial facilities. Therefore, the work begins with an analysis of past technological accidents triggered by floods. Thus, it was identified that Natech accidents are the consequences of hazardous materials releases from critical equipment, which in turn are damaged directly and indirectly by flood waters. Depending on the type of hazardous substances released, three categories of technological accidents are observed (fire, pollution and explosion). Afterwards, a risk analysis methodology was developed. It is mainly based on the MADS-MOSAR method, which was modified in order to be adapted to the Natech issue. The analysis resulted in the identification of five generic scenarios of technological accidents triggered by floods that can occur within an industrial installation. These scenarios were represented using the bow-tie tool. Then, around sixty preventive and protective measures were identified. The validation of the elaborated scenarios was done, on one hand, in the surface treatment industrial sector and, on the other hand, in two specific industrial facilities. The validation phase helped to test the completeness and plausibility of the generic scenarios, as well as the relevance of the measures previously identified. Furthermore, the validated scenarios were used to develop a checklist helping operators to decrease the vulnerability of their industrial facilities to technological accidents triggered by floods, along with a catalog of preventive and protective measures. Finally, the tool was applied to an industrial installation in order to enhance it and test its relevance by operators.

Esta tese investiga os discursos atuais, presentes no campo da educação e da sociedade em geral, que denunciam, ao mesmo tempo que promovem, a “carência do pai” no exercício da autoridade e nos cuidados da prole.Tais discursos emergem impulsionados pelas novas configurações familiares, recebidas como estranhas e ameaçadoras, podendo causar ruptura nos laços sociais. É possível perceber aí o efeito fantasmático que opera no discurso educativo, que acaba denunciando um fracasso antecipado, como efeito da nostalgia da família tradicional, cada vez mais distanciada de nossa realidade. Para investigar o que produz essa posição de reivindicação de um “pai forte”, nossa pesquisa foi buscar na teoria essas respostas. Buscamos recortar interpretantes do laço social e suas expressões sintomáticas. Para tal, expusemos o tema da função paterna, como surge nas obras de Freud e Lacan, buscando acompanhar sua incidência na estruturação do sujeito, desde o desamparo primordial. Trata-se de uma pesquisa teórica, que tem como questão os sentidos que as novas formas de exercício da função paterna têm para a educação, considerada como laço social. Com Freud, acompanhamos os desdobramentos da função paterna no complexo de Édipo e a abordagem da temporalidade do Édipo em Lacan permitiu situar o pai a partir do registro do imaginário, do simbólico e do real, em referência ao conceito de falo, como significante da falta no Outro. Tematizar a função paterna a partir desses registros permitiu diferenciar a função paterna simbólica da fantasmática presente na dimensão imaginária do pai, esse que é significado como “carente”. Usamos como dado empírico, alguns casos, tomados em sua exemplaridade, na perspectiva do tema da função paterna. A tese indica que, o diálogo da psicanálise com a educação, permite desmistificar construções fantasmáticas, indutoras de uma interpretação última dos sintomas sociais, como essa do discurso da carência paterna. Valer-se da pluralidade dos sentidos da função paterna na educação, é uma forma dos educadores responsabilizarem-se pelo ato educativo, numa posição de abertura às contingências históricas que as vicissitudes dos laços sociais produzem. / This thesis investigates the current discourses present in the education field and in the society in general, that denounce at the same time they promote the “lack of the father” in the authority exercise and the cares of the offspring. Such speeches emerge stimulated for the new familiar configurations, received as strange and threatening, being able to cause break in the social ties. It is possible to note there the fantasized effect that operates in the educative speech denouncing an anticipated failure, as effect of nostalgia of the traditional family, more and more distant from our reality. To investigate what produces this position of claim of a “strong father”, the author searches in the theory these answers. We elect interpreters of the social tie and its symptomatic expressions. For such, we displayed the issue of the paternal function, as it appears in Freud and Lacan works, searching to follow its incidence in the subject structuring, since the primordial abandonment.This work is a theoretical research that focus the senses that the new forms of exercise of the paternal function have for education, considered as social tie. With Freud, we follow the implications of the paternal function in the Oedipus complex and the approach of the temporality of the Oedipus in Lacan allowed to situate the father from the registers of the Imaginary, the Symbolic and the Real , in reference to the concept of phallus, as significant of the lack in the Other. Establishing as a theme the paternal function from these registers allowed to differentiate the symbolic paternal function, of the present fantasized in the imaginary dimension of the father, this that is meant as “lacking”. We use as empirical data, some cases, taken in their exemplarity, in the perspective of the subject of the paternal function. The thesis indicates that, the dialogue of psychoanalysis with education, allows demystifying fantasized inductive constructions of a last interpretation of the social symptoms, as this of the speech of the paternal lack. To use itself the plurality of the directions of the paternal function in education, is a form of the educators to make responsible for the educative act, in a position of opening to the historical contingencies that the vicissitudes of the social ties produce.

Esta tese investiga os discursos atuais, presentes no campo da educação e da sociedade em geral, que denunciam, ao mesmo tempo que promovem, a “carência do pai” no exercício da autoridade e nos cuidados da prole.Tais discursos emergem impulsionados pelas novas configurações familiares, recebidas como estranhas e ameaçadoras, podendo causar ruptura nos laços sociais. É possível perceber aí o efeito fantasmático que opera no discurso educativo, que acaba denunciando um fracasso antecipado, como efeito da nostalgia da família tradicional, cada vez mais distanciada de nossa realidade. Para investigar o que produz essa posição de reivindicação de um “pai forte”, nossa pesquisa foi buscar na teoria essas respostas. Buscamos recortar interpretantes do laço social e suas expressões sintomáticas. Para tal, expusemos o tema da função paterna, como surge nas obras de Freud e Lacan, buscando acompanhar sua incidência na estruturação do sujeito, desde o desamparo primordial. Trata-se de uma pesquisa teórica, que tem como questão os sentidos que as novas formas de exercício da função paterna têm para a educação, considerada como laço social. Com Freud, acompanhamos os desdobramentos da função paterna no complexo de Édipo e a abordagem da temporalidade do Édipo em Lacan permitiu situar o pai a partir do registro do imaginário, do simbólico e do real, em referência ao conceito de falo, como significante da falta no Outro. Tematizar a função paterna a partir desses registros permitiu diferenciar a função paterna simbólica da fantasmática presente na dimensão imaginária do pai, esse que é significado como “carente”. Usamos como dado empírico, alguns casos, tomados em sua exemplaridade, na perspectiva do tema da função paterna. A tese indica que, o diálogo da psicanálise com a educação, permite desmistificar construções fantasmáticas, indutoras de uma interpretação última dos sintomas sociais, como essa do discurso da carência paterna. Valer-se da pluralidade dos sentidos da função paterna na educação, é uma forma dos educadores responsabilizarem-se pelo ato educativo, numa posição de abertura às contingências históricas que as vicissitudes dos laços sociais produzem. / This thesis investigates the current discourses present in the education field and in the society in general, that denounce at the same time they promote the “lack of the father” in the authority exercise and the cares of the offspring. Such speeches emerge stimulated for the new familiar configurations, received as strange and threatening, being able to cause break in the social ties. It is possible to note there the fantasized effect that operates in the educative speech denouncing an anticipated failure, as effect of nostalgia of the traditional family, more and more distant from our reality. To investigate what produces this position of claim of a “strong father”, the author searches in the theory these answers. We elect interpreters of the social tie and its symptomatic expressions. For such, we displayed the issue of the paternal function, as it appears in Freud and Lacan works, searching to follow its incidence in the subject structuring, since the primordial abandonment.This work is a theoretical research that focus the senses that the new forms of exercise of the paternal function have for education, considered as social tie. With Freud, we follow the implications of the paternal function in the Oedipus complex and the approach of the temporality of the Oedipus in Lacan allowed to situate the father from the registers of the Imaginary, the Symbolic and the Real , in reference to the concept of phallus, as significant of the lack in the Other. Establishing as a theme the paternal function from these registers allowed to differentiate the symbolic paternal function, of the present fantasized in the imaginary dimension of the father, this that is meant as “lacking”. We use as empirical data, some cases, taken in their exemplarity, in the perspective of the subject of the paternal function. The thesis indicates that, the dialogue of psychoanalysis with education, allows demystifying fantasized inductive constructions of a last interpretation of the social symptoms, as this of the speech of the paternal lack. To use itself the plurality of the directions of the paternal function in education, is a form of the educators to make responsible for the educative act, in a position of opening to the historical contingencies that the vicissitudes of the social ties produce.

Este trabalho descreve um dormente monobloco de concreto protendido, o qual foi projetado para atender as características de uma via ferroviária brasileira. O dormente apresentou comportamento e resistência semelhantes aos dormentes de concreto comumente fabricados em vários países. A fim de verificar e aprovar o projeto, o dormente foi submetido a ensaios estáticos e dinâmicos, segundo as especificações da norma americana AREMA. Verificado e aprovado o projeto, dezoito dormentes foram fabricados sem e com fibras de aço, no teor de 60 kg/'M POT.3' (aproximadamente 0,75 % por volume). Ensaios estáticos e dinâmicos foram realizados em dormentes com e sem fibras de aço, com o objetivo de quantificar o benefício das fibras de aço à resistência estrutural do dormente. As fibras aumentaram o momento fletor de primeira fissura e o momento último, aumentaram significativamente a força de início de escorregamento dos fios de protensão e reduziram o espaçamento e a abertura das fissuras. As fibras também acrescentaram grande ductilidade aos dormentes e diminuíram a tensão nos fios de protensão, nos estágios mais avançados do carregamento. Sob ação dinâmica, as fibras reduziram a tensão nos fios de protensão mais tracionados em aproximadamente 100%, o que elevou significativamente a resistência do dormente à fadiga. Dormentes fabricados com menor força de protensão apresentaram excelente comportamento plástico e grande ductilidade, especialmente o dormente com fibras / This work describes a prestressed concrete monoblock railway sleeper designed according to a brazilian railway track. The sleeper was tested according to the Arema specifications in order to verify the project. The sleeper presented a structural behavior similar to the concrete railway sleepers used worldwide. After the preliminary tests, eighteen sleepers were manufactured without and with steel fibers contents of 60 Kg/'M POT.3' (about 0.75% by volume) and they were tested under static and dynamic loading to evaluate the fiber contribution on the resistance. Steel fibers increased the first crack and ultimate bending moments, reduced the deflection under ultimate load and increased significantly the slip force of the prestressing tendons. Reinforcing the sleeper with fibers also reduced the crack width and the spacing between cracks, adding higher ductility to the sleepers and decreasing the stress in the prestressing tendons under higher loads. The fibers increased significantly the fatigue strength under cyclic loading, decreasing the stress in the prestressing tendons in about 100%. The test results showed that sleepers manufactured with lower prestressed force have higher toughness, especially those reinforced with steel fibers

Esta tese investiga os discursos atuais, presentes no campo da educação e da sociedade em geral, que denunciam, ao mesmo tempo que promovem, a “carência do pai” no exercício da autoridade e nos cuidados da prole.Tais discursos emergem impulsionados pelas novas configurações familiares, recebidas como estranhas e ameaçadoras, podendo causar ruptura nos laços sociais. É possível perceber aí o efeito fantasmático que opera no discurso educativo, que acaba denunciando um fracasso antecipado, como efeito da nostalgia da família tradicional, cada vez mais distanciada de nossa realidade. Para investigar o que produz essa posição de reivindicação de um “pai forte”, nossa pesquisa foi buscar na teoria essas respostas. Buscamos recortar interpretantes do laço social e suas expressões sintomáticas. Para tal, expusemos o tema da função paterna, como surge nas obras de Freud e Lacan, buscando acompanhar sua incidência na estruturação do sujeito, desde o desamparo primordial. Trata-se de uma pesquisa teórica, que tem como questão os sentidos que as novas formas de exercício da função paterna têm para a educação, considerada como laço social. Com Freud, acompanhamos os desdobramentos da função paterna no complexo de Édipo e a abordagem da temporalidade do Édipo em Lacan permitiu situar o pai a partir do registro do imaginário, do simbólico e do real, em referência ao conceito de falo, como significante da falta no Outro. Tematizar a função paterna a partir desses registros permitiu diferenciar a função paterna simbólica da fantasmática presente na dimensão imaginária do pai, esse que é significado como “carente”. Usamos como dado empírico, alguns casos, tomados em sua exemplaridade, na perspectiva do tema da função paterna. A tese indica que, o diálogo da psicanálise com a educação, permite desmistificar construções fantasmáticas, indutoras de uma interpretação última dos sintomas sociais, como essa do discurso da carência paterna. Valer-se da pluralidade dos sentidos da função paterna na educação, é uma forma dos educadores responsabilizarem-se pelo ato educativo, numa posição de abertura às contingências históricas que as vicissitudes dos laços sociais produzem. / This thesis investigates the current discourses present in the education field and in the society in general, that denounce at the same time they promote the “lack of the father” in the authority exercise and the cares of the offspring. Such speeches emerge stimulated for the new familiar configurations, received as strange and threatening, being able to cause break in the social ties. It is possible to note there the fantasized effect that operates in the educative speech denouncing an anticipated failure, as effect of nostalgia of the traditional family, more and more distant from our reality. To investigate what produces this position of claim of a “strong father”, the author searches in the theory these answers. We elect interpreters of the social tie and its symptomatic expressions. For such, we displayed the issue of the paternal function, as it appears in Freud and Lacan works, searching to follow its incidence in the subject structuring, since the primordial abandonment.This work is a theoretical research that focus the senses that the new forms of exercise of the paternal function have for education, considered as social tie. With Freud, we follow the implications of the paternal function in the Oedipus complex and the approach of the temporality of the Oedipus in Lacan allowed to situate the father from the registers of the Imaginary, the Symbolic and the Real , in reference to the concept of phallus, as significant of the lack in the Other. Establishing as a theme the paternal function from these registers allowed to differentiate the symbolic paternal function, of the present fantasized in the imaginary dimension of the father, this that is meant as “lacking”. We use as empirical data, some cases, taken in their exemplarity, in the perspective of the subject of the paternal function. The thesis indicates that, the dialogue of psychoanalysis with education, allows demystifying fantasized inductive constructions of a last interpretation of the social symptoms, as this of the speech of the paternal lack. To use itself the plurality of the directions of the paternal function in education, is a form of the educators to make responsible for the educative act, in a position of opening to the historical contingencies that the vicissitudes of the social ties produce.

Made available in DSpace on 2014-07-29T15:18:23Z (GMT). No. of bitstreams: 1 ErikaSakai.pdf: 1917728 bytes, checksum: 5cc92bff51598c6d8147b5abba80383d (MD5) Previous issue date: 2010-12-16 / Through studies on the choice of type of foundation to use a certain work, always when the foundation is to pile it is necessary to build another structural element, the block of crowing or also called pile caps. Several studies have been made taking into account the block on stilts without the influence of soil. So this work demonstrates the relationship of methods of calculation of reactions in piles and tensions in chunks of some authors that take into account the influence of soil or not, with the numerical analysis. To analyzethe fundations the program DIANA was used in conjunction with MIDAS / FX +. With these results, ground-structure in the study of these blocks can be concluded on the importance of the interaction, being distinguished that as example, that if the ground are taken in consideration in the analyses of rigid blocks, the biggest reactions if are concentrate near the corners of the block, independent of the type of load application studied and not in the props central offices as some simplified methods consider. This leads to a closer examination of reality and therefore more accurate. / Através de estudos sobre a escolha do tipo de fundação a usar numa determinada obra, sempre quando a fundação for com estaca faz-se necessário a construção de outro elemento estrutural, o bloco de coroamento ou também denominado bloco sobre estacas. Vários estudos foram feitos levando-se em consideração o bloco sobre estacas sem a influência do solo. Portanto este trabalho demonstra a relação de métodos de cálculos de reações nas estacas e tensões nos blocos de estacas envolvidas pelo solo, através de análise numérica baseado no Método dos Elementos finitos, com características tridimensionais e não-lineares. Para a análise foi usado o programa DIANA em conjunto com o MIDAS/FX+. Com os resultados obtidos, pode-se concluir sobre a importância da interação solo estrutura no estudo destes blocos, destacandose que como exemplo, que se o solo é levado em consideração nas análises de blocos rígidos, as maiores reações se concentram nas estacas laterais do bloco, independente do tipo de aplicação de carga estudada e não nas estacas centrais como alguns métodos simplificados propõem. Isto leva a uma análise mais próxima da realidade e, consequentemente, mais preciso.

Introduction: Social networks have shown promise in curbing drug dependency and infectious diseases among marginalized populations. The purpose of this study is to elucidate how relationship strength in social networks is associated with risk behaviours for infectious diseases. Methods: Two reviews were conducted: 1) a systematic review exploring the association between risk behaviours and relationship strength 2) a review on the utilization of respondent driven sampling (RDS). We also analyzed network data to determine the association between recent injection drug use and recent crack use. Results: Our reviews revealed that few studies link relationship strength and risk behaviours; moreover, RDS is effective method of sampling from marginalized populations. Finally, our analysis demonstrated that close relationships are associated with drug use. Conclusion: “Close” relationships are important in arbitrating injection drug use and crack smoking. More research addressing the issues of using data from dynamic social processes and hard-to-reach populations is needed.

To achieve structural integrity in precast concrete systems, connections between elements must be capable to transfer both vertical and horizontal loads which puts high demands on single ties. Hollow-core slabs are often used to stabilize the structural system which puts high demands on the connections between the slab and the buildings stabilizing units. Because of this, the connections need to withstand high tensile and shear forces. The purpose of this report is to investigate the tensile capacity of tie-connections used between hollow-core slabs that are parallel with e.g. stabilizing walls and compare with current design methods. Current design methods suggest that tensile failure will occur in the roof and bottom of the cores which provides low design capacities. Two connections are investigated through full scale pull-out tests where the results are compared with the design methods. The results from testing the tensile capacity show that the failure module occurred as suggested. However, the tests show significantly higher capacity than proposed by the design methods. Eurocodes Design assisted by testing are applied to the test result and a new design method is proposed. Both provides design values that are approximately twice as large as the values suggested in previous design methods.

The finite element method is a powerful analysis tool which has facilitated a better understanding of the behaviour of reinforced concrete structures. Its use in the research field is widespread and complements experimental tests and the development of new analytical models. Its application in practice engineering has permitted to deal with complex elements. However, the general structural engineer is still reluctant to consider finite element modelling for his work as he finds most of these models excessively sophisticated for his needs and knowledge. In particular, complexity of many finite element tools usually derives from the adoption of advanced concrete constitutive models. Implementation of more simple models based on engineering practice could facilitate its use by less experienced finite element users. In structural engineering practice finite element analysis can be of great usefulness to deal with those more problematic elements and/or where the application of traditional analysis methods presents limitations. This includes the so-called D-regions with a 3D behaviour. The strut-and-tie method and the stress field method are consistent and rational tools for the analysis and design of D-regions, but while their application to 2D elements is well covered in literature, its extension to 3D is problematic. This generally explains why excessively conservative assumptions are still common in the design of these elements. Refinement of current analytical and design approaches or the use of finite element analysis could lead to more rational solutions which in turn will reduce material requirements and costs. A 3D nonlinear finite element-based tool was developed in this thesis oriented towards the analysis and design of 3D D-regions by less experienced finite element users. Regarding material modelling, an orthotropic concrete model was adopted to permit the use of uniaxial stress-strain relationships. Only one single parameter, the uniaxial compressive strength of concrete, needs to be defined. Additionally, several aid functions were implemented, among which the following can be highlighted: a comprehensive, embedded reinforcement model to facilitate the introduction of complex rebar geometries; special support and load elements permitting an integrated and simple treatment of the boundary conditions imposed by them; and a simple design algorithm for the automatic determination of the required rebar areas. Three examples of applications to representative 3D D-regions are presented to show the capabilities of the tool. In particular, the analyses of fourteen four-pile caps, three socket base column-to-foundations connections and one anchorage block are described in the third part of the thesis. Results prove that realistic response predictions can be obtained considering relatively simple constitutive models. The capacity of the tool to configure consistent stress field models depending on the reinforcement arrangement is also demonstrated. The generation of rational reinforcement configurations by applying the implemented design algorithm is also shown. A strut-and-tie-based method for the analysis and design of four-pile caps with rectangular geometries is proposed in the fourth part. The method is based on a refined 3D strut-and-tie model and the consideration of three potential modes of failure: exceeding the reinforcement strength, crushing of the diagonal strut at the base of the column with narrowing of the strut and splitting of the diagonal strut due to transverse cracking. The main innovation is that the strut inclination is not fixed as in current strut-and-tie-based design procedures, but determined by maximizing the pile cap strength. The method accounts for strength softening of cracked concrete, compatibility constraints and reinforcement details. Its application to 162 specimens of literature led to very good predictions of the ultimate strength and, to a lesser extent, of the mode of failure. / El método de los elementos finitos es una potente herramienta de análisis que ha facilitado un mejor conocimiento del comportamiento de las estructuras de hormigón armado. Su uso en el ámbito de la investigación está ampliamente extendido. Su aplicación en la práctica ingenieril ha permitido la resolución de elementos complejos. Sin embargo, el ingeniero estructural común todavía es reticente a usar la modelización por elementos finitos ya que considera que la mayoría de estos modelos son excesivamente sofisticados para sus necesidades. La complejidad de muchas herramientas de elementos finitos suele derivarse de la adopción de modelos constitutivos de hormigón avanzados. La implementación de modelos más sencillos podría facilitar su uso por usuarios menos experimentados. En la práctica ingenieril el análisis con elementos finitos puede ser de gran utilidad para tratar aquellos elementos más problemáticos y/o donde la aplicación de los métodos de análisis tradicionales presenta limitaciones. Esto incluye las llamadas regiones D con comportamiento 3D. El método de bielas y tirantes y el método de campos de tensiones son herramientas racionales para el análisis y dimensionamiento de regiones D, pero su extensión a 3D es problemática. Este hecho explica por qué se adoptan todavía hipótesis excesivamente conservadoras en el dimensionamiento de estos elementos. La propuesta de métodos analíticos y de diseño más adecuados o la modelización con elementos finitos podría conducir a soluciones más racionales, lo que a su vez reduciría las necesidades de material y los costes. Como parte de esta tesis se ha desarrollado una herramienta de cálculo no lineal basada en el método de los elementos finitos orientada al análisis y dimensionamiento de regiones D tridimensionales por usuarios con menos experiencia en la modelización con elementos finitos. Se ha adoptado un modelo ortotrópico para el hormigón para permitir el uso de relaciones uniaxiales de tensión-deformación. Sólo es necesario definir un único parámetro, la resistencia a compresión uniaxial del hormigón. Adicionalmente, se han implementado varias funciones de ayuda, entre las que destacan: un modelo de armadura embebida para facilitar la introducción de geometrías de armado complejas; elementos especiales de apoyo y de carga que permiten un tratamiento integral de las condiciones de contorno; y un algoritmo de diseño para la determinación automática del área de armado necesaria. Se presentan tres ejemplos de aplicación a regiones D 3D representativas para mostrar las capacidades de la herramienta. En concreto, en la tercera parte del documento se describen los análisis de catorce encepados, tres cálices de cimentación y un bloque de anclaje. Los resultados muestran que se pueden obtener predicciones bastante realistas considerando modelos constitutivos relativamente sencillos. También se demuestra la capacidad de la herramienta para configurar modelos de campo de tensiones consistentes dependiendo de la configuración de armado. Además se muestra la capacidad del algoritmo de diseño para configurar disposiciones de armado racionales. En la cuarta parte se propone un método para el análisis y dimensionamiento de encepados sobre cuatro pilotes con geometría rectangular. El método se basa en un modelo 3D de bielas y tirantes refinado y la consideración de tres modos de fallo posibles: rotura del acero, aplastamiento de la biela diagonal en la base de la columna con estrechamiento de la misma y splitting de la biela diagonal debido a la fisuración transversal. La principal novedad es que el ángulo de la biela no se fija como en otros modelos, sino que se determina mediante la maximización de la resistencia del encepado. El método considera el debilitamiento de la resistencia del hormigón fisurado, condiciones de compatibilidad de deformaciones y detalles de armado. Su aplicación a 162 especímenes dio luga / El mètode dels elements finits és una potent eina d'anàlisi que ha facilitat un millor coneixement del comportament de les estructures de formigó armat. El seu ús en l'àmbit de la investigació està àmpliament estès. La seua aplicació en la pràctica enginyeril ha permès la resolució d'elements més complexos. No obstant això, l'enginyer estructural comú encara és reticent a fer servir la modelització per elements finits ja que considera que la majoria d'aquests models són excessivament sofisticats per a les seues necessitats i el seu conèixement. En concret, la complexitat de moltes eines d'elements finits sol derivar-se de l'adopció de models constitutius avançats de formigó. La implementació de models més senzills basats en la pràctica enginyeril podria facilitar el seu ús per a usuaris menys experimentats en la modelització amb elements finits. A la pràctica enginyeril l'anàlisi amb elements finits pot ser de gran utilitat per a tractar aquells elements més problemàtics i/o on l'aplicació dels mètodes d'anàlisi tradicionals presenta limitacions. Això inclou les anomenades regions D amb comportament 3D. El mètode de bieles i tirants i el mètode de camps de tensions són eines racionals per a l'anàlisi i dimensionament de regions D, però la seua extensió a 3D és problemàtica. Aquest fet explica per què s'adopten encara hipòtesis excessivament conservadores en el dimensionament d'aquests elements. La proposta de mètodes analítics i de disseny més adequats o la modelització amb elements finits podria conduir a solucions més racionals, amb el que també es reduirien les necessitats de material i els costos. Com a part d'aquesta tesi s'ha desenvolupat una eina de càlcul no lineal basada en el mètode dels elements finits orientada a l'anàlisi i dimensionament de regions D tridimensionals per a usuaris amb menys experiència en la modelització amb elements finits. S'ha adoptat un model ortotròpic per al formigó per permetre l'ús de relacions uniaxials de tensió-deformació. Només cal definir un únic paràmetre, la resistència a compressió uniaxial del formigó. Addicionalment, s'han implementat diverses funcions d'ajuda, entre les quals destaquen: un model d'armadura embeguda per facilitar la introducció de geometries d'armat complexes; elements especials de suport i de càrrega que permeten un tractament integral i senzill de les condicions de contorn; i un algoritme de disseny per a la determinació automàtica de l'àrea d'armat necessari. Es presenten tres exemples d'aplicació a regions D 3D representatives per mostrar les capacitats de l'eina. En particular, en la tercera part del document es descriuen les anàlisis de catorze enceps sobre quatre pilons, 3 calzes de fonamentació i un bloc d'ancoratge. Els resultats mostren que es poden obtenir prediccions prou realistes considerant models constitutius relativament senzills. També es demostra la capacitat de l'eina per configurar models de camp de tensions consistents depenent de la configuració d'armat. A més es mostra la capacitat de l'algoritme de disseny per configurar disposicions d'armat racionals. En la quarta part es proposa un mètode per a l'anàlisi i dimensionament d'enceps sobre quatre pilons amb geometria rectangular. El mètode es basa en un model 3D de bieles i tirants refinat i la consideració de tres modes de fallada possibles: trencament de l'acer, aixafament de la biela diagonal a la base de la columna amb estrenyiment de la mateixa i splitting de la biela diagonal per causa de la fissuració transversal. La principal novetat és que l'angle de la biela no es fixa com en els models actuals de bieles i tirants, sinó que es determina mitjan\c{c}ant la maximització de la resistència de l'encep. El mètode proposat considera el debilitament de la resistència del formigó fissurat, condicions de compatibilitat de deformacions i detalls d'armat. La seua aplicació a 162 espècimens de la liter / Meléndez Gimeno, C. (2017). A finite element-based approach for the analysis and design of 3D reinforced concrete elements and its applications to D-regions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86193 / TESIS