Aunque el hormigón de alta resistencia se está utilizando de manera creciente en los últimos años para la construcción de estructuras, la norma Española vigente, la Instrucción EHE, sólo abarca hormigones de resistencias características a compresión inferiores a 50 MPa. El aumento de resistencia del hormigón está directamente asociado a una mejora en la mayoría de sus prestaciones, especialmente de la durabilidad, aunque también produce un aumento en la fragilidad y una disminución de la rugosidad de las fisuras, lo que afecta de forma muy especial a la resistencia a cortante.El objetivo principal de este trabajo es contribuir al avance del conocimiento del comportamiento frente a la rotura por cortante de vigas de hormigón de alta resistencia. Para ello, y en primer lugar, se ha llevado a cabo una extensa revisión del estado actual del conocimiento de la resistencia a cortante, tanto para hormigón convencional como para hormigón de alta resistencia, así como una profunda investigación de campañas experimentales anteriores. Se ha realizado una campaña experimental sobre vigas de hormigón de alta resistencia sometidas a flexión y cortante. La resistencia a compresión del hormigón de las vigas variaba entre 50 y 87 MPa. Las principales variables de diseño eran la cuantía de armadura longitudinal y transversal. Los resultados obtenidos experimentalmente han sido analizados para estudiar la influencia de las distintas variables en función de la resistencia a compresión del hormigón.Con el objetivo de tener en cuenta, no sólo los resultados de nuestros ensayos, sino también la gran cantidad de información disponible en la bibliografía técnica, se ha preparado una base de datos con vigas de hormigón convencional y de alta resistencia a partir del banco de datos de la Universidad de Illinois. Los resultados empíricos han sido comparados con los cortantes últimos calculados según la Instrucción EHE, las especificaciones AASHTO LRFD, el Código ACI 318-99 y el programa Response-2000, basado en la teoría modificada del campo de compresiones.Se han construido dos Redes Neuronales Artificiales (RNA) para predecir la resistencia a cortante en base a la gran cantidad de resultados experimentales. La principal característica de las RNA es su habilidad para aprender, mediante el ajuste de pesos internos, incluso cuando los datos de entrada y salida presentan un cierto nivel de ruido. Con los resultados de la RNA se ha realizado un análisis paramétrico de cada variable que afecta la resistencia última a cortante.Se han propuesto nuevas expresiones que tienen el cuenta el comportamiento observado para el diseño frente al esfuerzo cortante de vigas tanto de hormigón convencional como de alta resistencia con y sin armadura a cortante, así como una nueva ecuación para la determinación de la armadura mínima a cortante. Las nuevas expresiones presentan resultados que se ajustan mejor a los resultados experimentales que los obtenidos mediante la utilización de las normativas vigentes.Finalmente se han planteado varias sugerencias de futuras líneas de trabajo, que son resultado de la propia evolución del conocimiento sobre el tema de estudio durante el desarrollo de esta tesis. / Although High-Strength Concrete has been increasingly used in the construction industry during the last few years, current Spanish Structural Concrete code of practice (EHE) only covers concrete of strengths up to 50 MPa. An increase in the strength of concrete is directly associated with an improvement in most of its properties, in special the durability, but this also produces an increase in its brittleness and smoother crack surfaces which affects significantly the shear strength. The aim of this research is to enhance the understanding of the behaviour of high-strength concrete beams with and without web reinforcement failing in shear. In order to achieve this objective, an extensive review of the state-of-the-art in shear strength for both normal-strength and high-strength concrete beams was made, as well as in-depth research into previous experimental campaigns.An experimental programme involving the testing of eighteen high-strength beam specimens under a central point load was performed. The concrete compressive strength of the beams at the age of the tests ranged from 50 to 87 MPa. Primary design variables were the amount of shear and longitudinal reinforcement. The results obtained experimentally were analysed to study the influence of those parameters related to the concrete compressive strength.With the aim of taking into account, in addition to the results of our tests, the large amount of information available, a large database was assembled based on the University of Illinois Sheardatabank for normal-strength and high-strength concrete beams. These test results were compared with failure shear strengths predicted by the EHE Code, the 2002 Final Draft of EuroCode 2, the AASHTO LRFD Specifications, the ACI Code 318-99, and Response-2000 program, a computer program based on the modified compression field theory. Furthermore, two Artificial Neural Networks (ANN) were developed to predict the shear strength of reinforced beams based on the database beam specimens. An ANN is a computational tool made up of a number of simple, highly-interconnected processing elements that constitute a network. The main feature of an ANN is its ability to learn, by means of adjusting internal weights, even when the input and output data present a degree of noise. Based on the ANN results, a parametric study was carried out to study the influence of each parameter affecting the failure shear strength.New expressions are proposed, taking into account the observed behaviour for the design of high-strength and normal-strength reinforced concrete beams with and without web reinforcement. A new equation is given for the amount of minimum reinforcement as well. The new expressions correlate with the empirical tests better than any current code of practice.Finally, as a natural corollary to the evolution of our understanding of this field, some recommendations for future studies are made.

This master thesis focuses on structural analysis of combustion engine block. The main goal of this work was the design and compare individual solutions of long and short engine’s blocks. First part of work shows existing engine block designs and solutions. Based on the research part, the CAD design of the engine blocks and their discretization was performed by pre-processor programs. Structural analysis and their final comparison were provided by FEM and MBS programs.

Le massif des Beni Bou Ifrour, fenêtre de socle émergeant des bassins néogènes dans le Rif oriental, comprend les gisements de fer les plus importants du Maroc (> 60 Mt exploités de 1915 à 1976). Identifiés comme des skarns à magnétite, leur étude intégrée à plusieurs échelles permet d’en faire des traceurs de l’évolution crustale au sein de ce segment orogénique. A l’échelle du massif, les observations de terrain et microscopiques montrent que les disparités de géologie et de morphologie entre les gisements se révèlent être liées à leurs conditions de mise en place au sein du massif plutôt qu’à des conditions de genèse différentes des minéralisations. Ainsi un modèle en réseau de dykes et sills interconnectés (en « arbre de noël ») peut expliquer ces divergences, déterminées par la position structurale de chaque gisement. La mise à l’affleurement des minéralisations est liée au soulèvement du massif des Beni Bou Ifrour. Les observations de terrain étendues et les nouvelles contraintes chronologiques apportées (datations Ar-Ar, U-Pb, biostratigraphie…) permettent de construire un modèle de type pli sur chevauchement d’avant-pays, dont les translations et déformations majeures résultantes se produisent sur un intervalle de temps très court entre 8 et 6 Ma environ. A l’échelle du Rif oriental, le modèle déduit pour le massif des Beni Bou Ifrour est cohérent avec l’histoire régionale. Il confirme la prééminence de la compression dès 8 Ma, malgré la présence de failles normales qui accommodent en fait le soulèvement généralisé du massif. A l’échelle géodynamique, des analyses de la composition isotopique du Pb ont été réalisées sur les minéralisations épithermales à Pb-Zn associées aux skarns ferrifères. L’étude conjointe du magmatisme néogène trans-Alboran et de la Marge Maghrébine et la comparaison des compositions isotopiques du Pb avec des gisements associés permettent de mieux caractériser un épisode de rupture de panneau plongeant en Méditerranée occidentale, dont nous avons pu estimer la vitesse moyenne : environ 7-8 cm/an entre 20 et 8 Ma. / The Beni Bou Ifrour massif is a basement window surfacing among Neogene basins in the oriental Rif. It includes the biggest iron deposits of Morocco (> 60 Mt mined from 1915 to 1976). Identified as magnetite skarn deposits, a multi-scale integrated study allows to use them as tracers of the crustal evolution of this orogenic segment. At massif scale, field and microscopic observations display a diversity of geologic and morphologic features among the deposits. They appear to be linked to different emplacement conditions rather than genetic considerations. A dyke and sill inter-connected network (“christmas tree”) can thus explain those differences, determined by the structural position of each deposit. Outcropping of the mineralizations is related to the uplift of the Beni Bou Ifrour massif. Extended field observations and new chronological constraints (Ar-Ar and U-Pb datings, biostratigraphy…) allow to define an avant-pays thrust and fold model. Resulting translations and major deformations are restricted to a short time span between 8 and 6 Ma. At the Rif scale, this model of the Beni Bou Ifrour fits the regional history and attests the compression preeminence since 8 Ma, despite normal faults which accommodate the general uplift of the massif. At a geodynamic scale, Pb isotopic compositions have been performed on the epithermal Pb-Zn mineralizations associated to the iron skarn deposits. The combined study of Neogene Trans-Alboran and Mediterranean Maghreb margin and comparison of Pb isotopic compositions with associated deposits allow to constrain a slab breakoff event in western Mediterranean. We estimate its average velocity at about 7-8 cm/yr between 20 and 8 Ma.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-19T15:38:12Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Márcia Suzanna.pdf: 3055575 bytes, checksum: 6bc6b37e92f9ee9ac23e94abb75174c3 (MD5) / Made available in DSpace on 2017-04-19T15:38:12Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Márcia Suzanna.pdf: 3055575 bytes, checksum: 6bc6b37e92f9ee9ac23e94abb75174c3 (MD5) Previous issue date: 2016-09-23 / Atualmente, especialmente no Brasil, tem crescido a preocupação com o desempenho de estruturas sujeitas à ação de incêndios, devido aos riscos inerentes dessa situação. Por exemplo, somente em Pernambuco, no triênio 2011-2013, o Corpo de Bombeiros registrou a ocorrência média de 1600 incêndios/ano em edificações (residenciais, comerciais ou industriais). Catástrofes associadas a incêndios como esses podem resultar em elevados prejuízos financeiros, perda de patrimônio histórico/cultural, danos ao meio ambiente, além das irreparáveis perdas de vidas humanas, como as registradas na boate Kiss em Santa Maria – RS em 2013. Este trabalho visou analisar o desempenho ao fogo de pilares em aço, devido à grande relevância desse elemento para o projeto estrutural e, consequentemente, para segurança da edificação. Diversos fatores influenciam o comportamento de pilares em situação de incêndio, por exemplo: o esforço solicitante do serviço ao qual o pilar está submetido, a forma e dimensões da seção transversal, o índice de esbeltez do pilar e o comportamento das propriedades mecânicas e características dos materiais sob temperaturas elevadas. Devido à complexidade da influência dos parâmetros envolvidos na análise de estruturas em situação de incêndio, a resistência ao fogo dos elementos estruturais, como pilares, é determinada experimentalmente. No entanto, em geral, esses ensaios são caros e difíceis de serem realizados. Isso, por muitas vezes, inviabiliza o estudo de um número maior de amostras, não permitindo um melhor entendimento do problema. Nesse sentido, os modelos numéricos são de extrema importância para o estudo de estruturas em situação de incêndio, uma vez que tem sido possível reproduzi-los em razão dos avanços das técnicas de solução e modelagem numérica. Sendo assim, o objetivo desta pesquisa foi desenvolver modelos numéricos tridimensionais em elementos finitos para simular o comportamento de pilares em aço em situação de incêndio, permitindo a utilização desses modelos em análises paramétricas futuras para a determinação da resistência ao fogo de pilares. Testaram-se dois programas largamente utilizados na análise numérica de estruturas: o ANSYS e o ABAQUS. Validaram-se por comparação os resultados numéricos com experimentos publicados na literatura internacional e nacional. Consideraramse relevantes para a determinação da resistência ao fogo os seguintes parâmetros: nível de carga, rigidez da estrutura circundante, formas e dimensões da seção transversal. Os resultados apontaram que os modelos e estratégicas numéricas utilizadas mostraram-se adequados para fins de análises térmicas e termoestruturais, sendo capazes de prever o comportamento térmico e mecânico dos pilares tubulares de aço em situação de incêndio, com boa correlação com os resultados experimentais. As colunas apresentaram tempos críticos inferiores aos divulgados na literatura. O aumento da rigidez axial não influenciou de maneira significativa nos tempos críticos das análises. As forças de restrições relativas foram maiores para os menores níveis de cargas. / Currently, especially in Brazil, the performance of structures subjected to fire action has been a great concert, due to the risks inherent in this situation. For example, only in Pernambuco, in the triennium 2011-2013, the Fire Department reported the increase of 1600 fires per year in buildings (residential, commercial or industrial). Disasters associated with fire as these can result in significant financial loss; historical, cultural, environmental damage, in addition to irreparable losses of human life as occurred in the Kiss nightclub in Santa Maria - RS (2013). This work aims to analyze the performance of steel columns on fire due to the great importance of this element for the structural design and the consequent safety of the building. Several factors influence the behavior of columns in fire situation, quotes, for example, the load level at which the post is submitted, the form and dimensions of the cross section, the slenderness ratio of the column and the behavior of the mechanical properties and characteristics of materials under elevated temperatures. Because of the complexity of the parameters involved in the analysis of structures in case of fire, the fire resistance of structural elements like pillars is determined experimentally. However, in general, these tests are expensive and difficult to perform. This often negatively affects the study of a large number of samples, not allowing a better understanding of the problem. In this sense the numerical models are extremely important for the study of structures in fire, as it has been possible to play them because of advances in solving techniques and numerical modeling. Thus, the objective of this research is to develop three-dimensional numerical models in finite elements to simulate the behavior of steel columns in fire situation, allowing the use of models in future parametric analysis to determine the fire resistance of columns. Two programs widely used in numerical analysis of structures were tested: ANSYS and ABAQUS. The numerical results were validated by comparison with experiments published in the international and national literature. Relevant parameters to the determination of the fire resistance were considered: load level, stiffness of the surrounding structure, shape and dimensions of the transverse section were considered.

This research puts forward as its central subject an inquiry into the existence of an underground lateral flow capable of carrying particles that leads to morfogenetical implications. Regarding the pertinence to this analysis of a survey by Werlang et al. (2014), this project builds on the conclusions reached by the application of the pedological cover structural analysis in a toposequence. From these outcomes, as well as due to the significant finding of a notorious low hydraulic conductivity of the underground horizons proven in trials, it was possible identify a lateral flow predominantly on the eluvial horizon. In an area next to that the mentioned study took place, we selected a hillslope to proceed a preliminary topographic survey to define the hillslope geomorphic nature and set up the geomorphic breaking points of this hillslope. Subsequently, this allowed to conduct the soil sounding along the toposequence of eleven points in these geomorphic breaking points, determining depth and thickness of the present horizons and collecting samples for laboratory analysis. Similarly, the morphological description of the probed profiles was performed. After this stage of field works, a new topographic survey was conducted designed to locate, within the mentioned area, the probing points aiming at obtaining a profile of the hillslope topossequence segment data. This procedure allowed to obtain a bidimensional analysis of the pedological cover and enabled to develop several substantial inferences. Taking into account the results of this analysis, we proceed to characterize, both in field and laboratory, the present litology condition in the area on the Santa Maria Formation. The samples obtained in field allowed to accomplish the granulometrical characterization, and next, tabulate these data. In this way, the discussion could identify gradients of concentration from different granulometrical grades, which were then used to define a dynamics based on surface and underground flows supporting a wide discussion engaged thereof. The presence of positive gradients, albeit tenuous, in the clay fraction down the slope, afforded to infer the existence of a subsurface flow with transport and further accumulation of material on top of the B horizon of profiles located at lower levels. Accordingly, this allowed to testify the validity of purpose of this study, noting however the presence of two distinct litologies from the Santa Maria Formation whose permeability has shown that the dynamics of the hillslope is highly complex insomuch as inserted in the landscape as a whole. / O presente estudo propõe a investigação da existência de um fluxo lateral subsuperficial carreador de partículas com implicações morfogenéticas. Considerando a pertinência para nossa análise de um trabalho de Werlang et al. (2014), este projeto toma como base as conclusões obtidas com a aplicação da análise estrutural da cobertura pedológica em uma topossequência. A partir dessas considerações, bem como da significativa constatação de uma notória baixa condutividade hidráulica dos horizontes subsuperficiais comprovada em ensaios, foi possível identificar um fluxo lateral predominante no horizonte E ao longo da topossequência. Em uma área próxima a do estudo mencionado, foi selecionado um segmento de vertente a partir do qual se procedeu ao levantamento topográfico preliminar e definiu-se os pontos de ruptura geomórfica deste segmento de vertente. Subsequentemente, foram realizadas sondagens ao longo da topossequência nos pontos destas rupturas geomórficas, determinando profundidade e espessura dos horizontes presentes e coletando amostras para análise laboratorial. Foi realizada também a descrição morfológica dos perfis sondados. Finalizada esta etapa dos trabalhos de campo, efetuou-se um novo levantamento destinado a situar, dentro da área referida, os pontos de sondagem visando possibilitar a obtenção de um perfil da topossequência do segmento de vertente. O procedimento permitiu uma análise bidimensional da cobertura pedológica que subsidiou inferências significativas. Contabilizando os resultados dessa análise, foi caracterizada em campo e em laboratório a situação das litologias presentes na área relativa à Formação Santa Maria. Com as amostras resultantes deste procedimento foi possível realizar a análise granulométrica, sendo a seguir tabulados e discutidos os dados obtidos. Foi possível então identificar gradientes de concentrações das diferentes classes granulométricas, que foram utilizados para definir uma dinâmica de fluxos em superfície e subsuperfície subsidiando as discussões. A presença de gradientes positivos, ainda que tênues, na fração argila no sentido do declive da vertente, possibilitou inferir a existência de um fluxo subsuperficial com carreamento e acúmulo de materiais no topo do horizonte B dos perfis situados em cotas inferiores. Isso permitiu constatar a validade do propósito deste estudo, observando que a presença de duas litologias de permeabilidade distintas tenha demonstrado que a dinâmica de uma vertente é invariavelmente complexa, visto que inserida no todo da paisagem e contemplando mais de um fator determinante.

In the present study, we compare factor analytic models of post-traumatic stress disorder (PTSD) in terms of their fit and predictive utility with regard to external correlates such as comorbid diagnoses and other psychosocial outcomes. Competing models were compared and validated in an epidemiological dataset (N = 23,936). Confirmatory factor analyses (CFA) using models from prior literature with four through seven factor solutions were conducted. The seven factor Hybrid model, the six-factor Anhedonia model, and the six-factor Externalizing Behaviors model were the first, second, and third best-fitting models, respectively; however, the inconsistency of associations with external correlates and high factor intercorrelations suggested that higher-factor solutions may sacrifice parsimony for minimal gains in utility. The Anhedonia and Hybrid models’ separate Anhedonia and Negative Affect factors (a core difference from other models) demonstrated limited utility in differentially associating with distinct constructs under the internalizing umbrella. Anhedonia and Negative Affect also correlated highly with each other and nearly perfectly with the factors composed of their combined symptoms (e.g. the Externalizing Behaviors model’s Numbing factor), suggesting a "lumped" factor would be more parsimonious. The Externalizing Behaviors model showed predictive utility in accounting for externalizing comorbidities as well as differentiating among constructs within the internalizing spectrum; however, it lacked robust associations with externalizing behavioral outcomes such as frequency and quantity of drinking. These results give reason for concern that predominant structural models of PTSD may not be adequate for discriminating among or predicting functional outcomes related to PTSD symptomatology in trauma-exposed populations.<br>