Bridge abutments are designed to withstand lateral pressures from thermal expansion and seismic forces. Current design curves have been seen to dangerously over- and under-estimate the peak passive resistance and corresponding deflection of abutment backfills. Similar studies on passive pressure have shown that passive resistance changes with different types of constructed backfills. The effects of changing the length to width ratio, or including MSE wingwalls determine passive force-deflection relationships. The purpose of this study is to determine the effects of the wall heights and of the MSE support on passive pressure and backfill failure, and to compare the field results with various predictive methods. To compare the effects of backfill geometries, three large-scale tests with dense compact sand were performed with abutment backfill heights of 3 ft (0.91 m), 5.5 ft (1.68 m), and 5.5 ft (1.68 m) confined with MSE wingwalls. Using an existing pile cap 11 ft (3.35 m) wide and 5.5 ft (1.68 m) high, width to height ratios for the abutment backfills were 3.7 for the 3ft test, and 2.0 for the 5.5ft and MSE tests. The failure surface for the unconfined backfills exhibited a 3D geometry with failure surfaces extending beyond the edge of the cap, increasing the "effective width", and producing a failure "bulb". In contrast, the constraint provided by the MSE wingwalls produced a more 2D failure geometry. The "effective width" of the failure surface increased as the width to height ratio decreased. In terms of total passive force, the unconfined 5.5ft wall provided about 6% more resistance than the 5.5ft MSE wall. However, in terms of passive force/width the MSE wall provided about 70% more resistance than the unconfined wall, which is more consistent with a plane strain, or 2D, failure geometry. In comparison with predicted forces, the MSE curve never seemed to fit, while the 3ft and 5.5ft curves were better represented with different methods. Even with optimizing between both the unconfined curves, the predicted Log Spiral peak passive forces were most accurate, within 12% of the measured peak resistances. The components of passive force between the unconfined tests suggest the passive force is influenced more by frictional resistance and less by the cohesion as the height of the backwall increases.

Made available in DSpace on 2014-07-29T15:18:23Z (GMT). No. of bitstreams: 1 Dissertacao Denise Vaz de Campos.pdf: 1915158 bytes, checksum: a102b2411e2e162cde4e66eeca8bc624 (MD5) Previous issue date: 2011-08-22 / The structural sizing pile caps on piles has traditionally been run in simplified manner, disregarding the three-dimensional effect of structural piece. Use the concept of piled cap in calculating enriches scalability providing an understanding of internal efforts on the basis of a distribution of more realistic reactions in the block. The goal of this work was to check the differences in structural sizing pile caps using traditional methods and two numerical methods, one based on finite elements and other hybrid that combines finite elements with elements of the boundary. The main comparison between methods was the internal moment generated in the block after the application of vertical load, for being one of the main parameters of scaling of the armature. In Brazil the scaling manual methods most used are based on the theory of rods or theory of beams. The method of connecting rods, and rods considers inside the block, at the bottom, tensile stress that are combated by frame, and method of the beams is calculated as an internal moment found by reaction of piles and the lever arms to the section you want, and then the block is sized like a beam. The numerical methods presented using the concept of piled raft in scale of blocks. In numerical methods have been used DIANA and GARP programs, which provide internal moments throughout the block of three-dimensional shape and thus were made a comparison with the manual method by the theory of beams. Were simulated blocks with 2, 4, 9, 25, 64 and 81 piles with loads applied in different ways for an assessment of the effect of the size of blocks, of the comparisons performed can be observed that in the manual method and numerical methods total found moments are very close, but with a differentiated distribution along the sections of the blocks, which becomes more apparent as it increases the amount of piles per block. For the manual methods in the center of the block the internal moments are inferior to scaled as piled raft, necessitating an additional frame in this region. / Tradicionalmente, o dimensionamento estrutural de blocos sobre estacas tem sido executado de forma simplificada, desconsiderando o efeito tridimensional da peça estrutural. Utilizar o conceito de radier estaqueado no cálculo enriquece o dimensionamento proporcionando um conhecimento dos esforços internos com base numa distribuição de reações mais realistas no bloco. O objetivo deste trabalho foi de verificar as diferenças no dimensionamento estrutural de blocos sobre estacas utilizando os métodos tradicionais e dois métodos numéricos, um baseado em elementos finitos e outro híbrido que combina elementos finitos com elementos de contorno. A principal comparação entre os métodos foi o momento interno gerado no bloco após a aplicação de carga vertical, por ser um dos principais parâmetros de dimensionamento da armação. No Brasil, os métodos manuais de dimensionamento mais utilizados são baseados na teoria das bielas ou teoria das vigas. O método das bielas e tirantes considera, no interior do bloco, na parte inferior, tensões de tração que são combatidas pela armação, e no método das vigas é calculado um momento interno encontrado pela reação das estacas e os braços de alavanca até a seção desejada e o bloco é dimensionado como uma viga. Os métodos numéricos apresentados utilizam o conceito de radier estaqueado no dimensionamento dos blocos. Nos métodos numéricos foram utilizados os programas DIANA e GARP, que fornecem os momentos internos em todo o bloco de forma tridimensional. E os resultados foram comparados com o método manual pela teoria das vigas. Foram simulados blocos com 2, 4, 9, 25, 64 e 81 estacas com cargas aplicadas de distintas formas para uma avaliação do efeito do tamanho dos blocos. Das comparações executadas observou-se que no método manual e nos métodos numéricos os momentos totais encontrados são muito próximos, porém com uma distribuição diferenciada ao longo das seções dos blocos, que se torna mais evidente à medida que se aumenta a quantidade de estacas por bloco. Para os métodos manuais no centro do bloco os momentos internos são inferiores aos dimensionados como radier estaqueado, necessitando de uma armação complementar nesta região.

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

Pile groups are often used to provide support for structures. Capping a pile group further adds to the system's resistance due to the passive earth pressure from surrounding backfill. While ultimate passive earth pressure under static loading conditions can be readily calculated using several different theories, the effects of cyclic and dynamic loading on the passive earth pressure response are less understood. Data derived from the full-scale testing of a pile cap system with a densely compacted sand backfill under static, cyclic, and dynamic loadings was analyzed with particular focus on soil pressures measured directly using pressure plates. Based on the testing and analyses, it was observed that under slow, cyclic loading, the backfill stiffness was relatively constant. Under faster, dynamic loading, the observed backfill stiffness decreased in a relatively linear fashion. During cyclic and dynamic loading, the pile cap gradually developed a residual offset from its initial position, accompanied by a reduction in backfill force. While the pile cap and backfill appeared to move integrally during static and cyclic loadings, during dynamic loading the backfill exhibited out-of-phase movement relative to the pile cap. Observed losses in backfill contact force were associated with both cyclic softening and dynamic out-of-phase effects. Force losses due to dynamic loading increased with increasing frequency (which corresponded to larger displacements). Losses due to dynamic loading were offset somewhat by increases in peak force due to damping. The increase in contact force due to damping was observed to be relatively proportional to increasing frequency. When quantifying passive earth forces with cyclic/dynamic losses without damping, the Mononobe-Okabe (M-O) equation with a 0.75 or 0.8 multiplier applied to the peak ground acceleration can be used to obtain a reasonable estimate of the force. When including increases in resistance due to damping, a 0.6 multiplier can similarly be used.

The final thesis is focused on the design and assessement of precast structure of industrial hall – with purlin, prestressed girder, columns, grade beam, pile cap and pile. Structural analysis was performed by SCIA Engineer 2015 and hand calculations.

The subject of this master’s thesis is a solution of chosen parts of building construction project. The project solves industrial hall that contains productions and administrative space. This thesis includes technological regulations for substructure, study of performing the main technological stages, design of using machines, checking and testing plans. Other phrases parts are time schedules, budget, calculations, design of site equipment including engineering report and report for performing access road. Starting materials, which were used for this thesis, were engineering report also including working drawings.