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Mangalaramanan, Sathya Prasad. "Robust limit loads using elastic modulus adjustment technique." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25774.pdf.
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Fowler, Christopher G. "Robust estimation of limit loads for cracked components." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ42382.pdf.
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Lynch, Michael Anthony. "Limit loads of piping branch junctions with cracks." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399152.
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Ralph, Freeman E. "Robust methods of finite element analysis : evaluation of non-linear, lower bound limit loads of plated structures and stiffening members /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/MQ54953.pdf.
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Jamtsho, Lungten. "Performance load testing and structural adequacy evaluation of road bridge decks." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/46822/1/Lungten_Jamtsho_Thesis.pdf.
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Many ageing road bridges, particularly timber bridges, require urgent improvement due to the demand imposed by the recent version of the Australian bridge loading code, AS 5100. As traffic volume plays a key role in the decision of budget allocations for bridge refurbishment/ replacement, many bridges in low volume traffic network remain in poor condition with axle load and/ or speed restrictions, thus disadvantaging many rural communities. This thesis examines an economical and environmentally sensible option of incorporating disused flat rail wagons (FRW) in the construction of bridges in low volume, high axle load road network. The constructability, economy and structural adequacy of the FRW road bridge is reported in the thesis with particular focus of a demonstration bridge commissioned in regional Queensland. The demonstration bridge comprises of a reinforced concrete slab (RCS) pavement resting on two FRWs with custom designed connection brackets at regular intervals along the span of the bridge. The FRW-RC bridge deck assembly is supported on elastomeric rubber pads resting on the abutment. As this type of bridge replacement technology is new and its structural design is not covered in the design standards, the in-service structural performance of the FRW bridge subjected to the high axle loadings prescribed in AS 5100 is examined through performance load testing. Both the static and the moving load tests are carried out using a fully laden commonly available three-axle tandem truck. The bridge deck is extensively strain gauged and displacement at several key locations is measured using linear variable displacement transducers (LVDTs). A high speed camera is used in the performance test and the digital image data are analysed using proprietary software to capture the locations of the wheel positions on the bridge span accurately. The wheel location is thus synchronised with the displacement and strain time series to infer the structural response of the FRW bridge. Field test data are used to calibrate a grillage model, developed for further analysis of the FRW bridge to various sets of high axle loads stipulated in the bridge design standard. Bridge behaviour predicted by the grillage model has exemplified that the live load stresses of the FRW bridge is significantly lower than the yield strength of steel and the deflections are well below the serviceability limit state set out in AS 5100. Based on the results reported in this thesis, it is concluded that the disused FRWs are competent to resist high axle loading prescribed in AS 5100 and are a viable alternative structural solution of bridge deck in the context of the low volume road networks.
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Majdič, Petr. "Napěťová, deformační a bezpečnostní analýza statoru generátoru zatíženého nehomogenní teplotou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231962.
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This thesis deals with stress, strain and reliability analysis of synchronous generator stator including an inhomogeneous temperature field. Using the finite element method, stress and strain are calculated, and from these values safety against yield strength is determined, which is followed by the life calculation of the most stressed weld joint and the determination of its possible damage during the period required by the customer.
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Matuška, Vojtěch. "Porovnání variant nádrže ČOV z železobetonu a z předpjatého betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409800.
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The diploma thesis deals with design and comparison of variants of cast-in-place concrete sewage tank made from reinforced concrete and pre-stressed concrete. The layout of sewage tank is rectangular. The tank is in longitudinal way divided into two chambers. The tank is not roofed and is partialy embedded in the ground. The design for ultimate limit state and for service limit state is made for both variants. There is focus on generation and development of cracks in service limit state. For calcuation of internal forces is used model made in software SCIA Engineer, based on finite element method. The reinforced concrete and pre-stressed concrete versions are compared in last part in term of volumes of materials needed. Also there are proposed possible savings.
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Hrycík, Martin. "Vícepodlažní budova." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226900.
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Thesis deals with design of steel structure multi-storey office building. Specifically, it is the eight-storey steel structure of rectangular plan with dimensions of 15.4 x 54.4 m and a height of 29.2 meters. The structure is designed for the site Brno. Static calculation is solved by a combination of manual calculation and calculation using software Scia. It is designed structural arrangement, static action, load analysis, calculation of internal forces, the design of dimensions and connections solutions. Thesis includes drawing documentation. The structure is designed in a variant with a frame joints and in variant with articulated joints. Variant with articulated joints is further processed.
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Maršalová, Jiřina. "Dvorní vícepodlažní přístavba výukových prostor." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240376.
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The master thesis is focused on design and static calculations of fiber reinforced concrete ground slab. The assessed structure is composed of 6 floors and 2 underground floors. A ground slab is based on piles and designed as a waterproof structure. The structural analysis program RFEM 5.05 has been used for calculation of internal forces.
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Novotný, Petr. "Obchodní a administrativní centrum." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227699.
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The aim of this master´s thesis was design and analysis of a steel supporting structure of a building for business and administration purposes in Ostrava. It includes an assessment of the main load-bearing construction elements and the selected connections. The thesis also contains the design documentation of the building and compares two different variants of the steel construction design.
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Prado, José Fernão Miranda de Almeida. "Estruturas de edifícios em concreto armado submetidas a ações de construção." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-11122017-111943/.
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As ações presentes durante a construção de estruturas de edifícios em concreto armado são significantemente influenciadas pelo processo construtivo e podem ultrapassar a capacidade resistente definida no projeto estrutural. Os pavimentos recém concretados são suportados por pavimentos previamente concretados, através de um sistema de fôrmas, escoras e reescoras. Se houver fissuração prematura os pavimentos terão maiores deformações ao longo do tempo. Assim sendo, o trabalho apresenta um procedimento de análise estrutural que leva em conta a seqüência natural de construção. A definição das ações nos pavimentos durante a construção estabelece a história de carregamentos dos elementos estruturais do início ao fim da obra. Os modelos tridimensionais (utilizando o método dos elementos finitos) aqui apresentados consideram que o tempo altera as propriedades de resistência e deformabilidade do concreto antes dos 28 dias. Com isso, é definido um novo método para a determinação da distribuição das ações de construção entre o sistema de escoramento e os pavimentos interligados (Método Aproximado). Além disso, propõe-se uma nova metodologia para verificação dos estados limites considerando a existência das etapas de construção.<br>The loads during construction of multistory reinforced concrete structures are significantly influenced by the construction schedule and can exceed the supporting structure\'s design capacity. The fresh floors are supported by previously cast floors, through a system of forms, shores and reshores. If cracked prematurely, the floors will have larger time-dependent deflections. Then, the text presents a procedure for structural analysis that takes into account the natural sequence of construction. Definition of the loads on floors during construction provides a view of the history of structural element loads from the beginning to the end of construction work. The tridimensional models (using the finite element method) presented herein considers that the time affects the strenght and deformability properties of concrete before 28 days. Then, a new method for determining how the construction loads are distributed among the shoring system and the interconnected floors is defined (Approximated Method). Further, a new methodology for the limit states verification taking into account the construction phases is proposed.
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Dorji, Jigme. "Strength and serviceability assessment of aged masonry arch bridges." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/213050/1/Jigme_Dorji_Thesis.pdf.
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This thesis investigated strength and serviceability of aged masonry arch bridges which exist in rail track networks in Australia. The method is based on the measurement of structural responses under operating loads and experimental tests. Two typical bridges were investigated for Australian Rail and Track Corporation Ltd (ARTC) and found that the bridges are safe against the operating loads, despite having undergone aging phenomenon.
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Vyhnalíková, Kateřina. "Betonová konstrukce krytého parkoviště pro bytové domy." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240439.
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The aim of diploma thesis is a design and an assessment of selected structural elements of one floor in monolithic concrete structures serving as covered parking for an apartment house. Software RFEM is used here to calculate internal forces. The thesis also includes manual calculation of internal forces and comparison with software results. It also includes drawings of proposed solution. All calculation are done in accordance with Eurocode 2.
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Duda, Tomáš. "Statické řešení střešní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226743.
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The subject of the diploma thesis is the design and static analysis of roof structure. It is prestressed roof shell (membrane) supported by a cable. The whole thesis is divided into several separated units according to task's specification. The text section describes the introduction to the issue of presstressed suspension cable constructions and displays their possible shapes, types and realizations. There is also technical report of solved shell, which was written on the base of the documents, drawn drawings and structural (static) analysis.
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Anderson, Nathan (Nathan Charles). "Examination of the high load limit of an HCCI engine." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43137.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.<br>Includes bibliographical references (p. 72).<br>The implementation of homogenous charge compression ignition (HCCI) to gasoline engines is constrained by many factors. This work examines constrains imposed by nitric oxide (NOx) emission and by the need to maintain a minimum catalyst temperature on HCCI operation. Then the nature of the approach to high load limit was examined for three fuels with very different behavior.An engine simulation was used to examine constrains imposed by NOx emission and by catalyst temperature requirement. The valve timing in a HCCI engine using NegativeValve-Overlap (NVO) was varied in the simulation to control the operating point. The engine speed and intake pressure (turbocharged mode) were varied. The High Load Limit (HLL) was attained when the NOx emission reached the regulated level for a Partial-Zero-Emissions-Vehicle (PZEV). This occurred when the engine was running at the lowest speed and the highest intake pressure. Unreasonably large residual fraction was required to achieve the NOx limit unless a three-way catalyst is used.The engine behavior in the operating trajectory to the HLL was examined by using two Primary Reference fuels (PRF60 and PRF90) and a fuel blended from refinery feed stock. The latter fuel had Extremely Low Aromatic and Olefin content and is referred to as the ELAO fuel. For PRF60 (the knock prone fuel), the Maximum Pressure Rise Rate (MPRR) increased with increase in load (by reduction of residual). The HLL was attained when the MPRR reached a pre-determined level of 5MPa/ms. For PRF90 (the knock resistant fuel), however, the MPRR decreased with increase in load, and the HLL was constrained by ignition failure. For the ELAO fuel, the MPRR first increased and then decreased with increase in load. The HLL was thus constrained by ignition failure. Thus depending on the fuel properties, there could be very different engine behaviors in the approach to the HLL of HCCI operation.<br>by Nathan Anderson.<br>S.M.
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Novak, Wilhelm. "Local limit load solutions for semi-elliptical surface cracks in plates subjected to combined membrane load and bending load." Thesis, KTH, Hållfasthetslära (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176405.
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Local limit load solutions for plates containing semi-elliptical surface cracks subjected to pure membrane loading cases, pure bending loading cases and combinations of the two are determined using non-linear finite element analysis. Both loading cases that open the crack and loading cases that close the crack are considered. The study covers both shallow and deep cracks with different aspect ratios. Results from the finite element simulations are fitted to an analytical expression. The local limit load solutions from this work are compared with global and local limit load solutions from previous work. Furthermore, infinite cracks and the effect of crack-face contact are investigated.<br>Lokala gränslastlösningar för plana plåtar innehållande semi-elliptiska ytsprickor som belastas med en membranlast eller en böjlast eller en kombination av båda är presenterade. Lastfall som både öppnar och stänger en spricka beaktas. Lösningarna är framtagna med hjälp av icke-linjär FE-analys. Arbetet omfattar både grunda och djupa sprickor med olika längd-djupförhållanden. Resultaten från FEanalyserna är kurvanpassade till ett analytiskt uttryck. De lokala gränslastlösningarna jämförs sedan med tidigare framtagna globala och lokala gränslastlösningar. Dessutom undersöks plana plåtar med oändliga sprickor och inverkan av kontakten som uppstår mellan sprickytorna.
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Dujc, Jaka. "Finite element analysis of limit load and localized failure of structures." Cachan, Ecole normale supérieure, 2008. http://tel.archives-ouvertes.fr/tel-00505153/fr/.
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Ce travail a pour objet l’analyse limite des structures par la méthode des éléments finis. Lorsqu’une structure atteint sa charge limite, certaines de ses composantes sont dans la phase inélastique de leur comportement, alors que dans les parties les plus critiques, du fait de la localisation des déformations inélastiques, se produit la rupture du matériau. Les effets de localisation sont, dans les matériaux fragiles liés à l’apparition et au développement de macro fissures alors qu’ils sont, dans les matériaux ductiles, gouvernés par les bandes de cisaillement localisées. L’étude de la charge limite est ainsi reliée à la modélisation du comportement inélastique standard du matériau mais également à la modélisation des effets localisés correspondant au comportement adoucissant des matériaux. Le comportement inélastique standard du matériau est, dans ce travail, décrit par des modèles élastoplastiques, élastoviscoplastiques ou élastiques non linéaires. Tous les modèles de comportement sont définis en termes d’efforts généralisés. Un certain nombre d’approches mathématiques et d’algorithmes numériques sont disponibles mais sont bien souvent inefficaces et manquent de précision. Ainsi, nous utilisons une approche développée plus récemment s’appuyant sur une méthode d’éléments finis enrichis de discontinuités. Nous avons développé de nouvelles formulations d’éléments standards prenant en compte des cinématiques et des descriptions des champs de déplacements discontinus complexes. Plusieurs formulations d’éléments finis ont été développées pour l’analyse de différents composants structurels. Nous présentons, dans un premier temps, un élément fini dédié à l’analyse limite des plaques en béton armé. La formulation d’un élément de plaque élastoplastique et élastoviscoplastique écrite en efforts généralisés associée à une procédure commune d’intégration sont présentées ensuite. Un élément de coque non linéaire, faisant intervenir une fonction seuil à deux surfaces incluant à la fois un écrouissage isotrope et un écrouissage cinématique est ensuite présenté. Les deux derniers éléments finis développés dans ce travail sont dédiés à la modélisation de la rupture localisée dans les poutres planes et les solides bidimensionnels. L’élément de poutre d’Euler-Bernouilli est enrichi par une discontinuité en rotation. Une stratégie s’appuyant sur l’analyse préalable, par un modèle raffiné, d’une partie de la structure est proposée afin d’obtenir les paramètres du modèle constitutif de la poutre. Enfin, nous présentons la formulation d’un élément quadrangulaire à discontinuité forte dont la cinématique permet de prendre en compte des sauts de déplacements linéaires dans les deux directions normale et tangentielle le long de la surface de discontinuité. Des résultats numériques montrent que les éléments développés ainsi que les algorithmes associés constituent un outil efficace et robuste d’analyse de la charge limite et de la rupture des structures. Parmi les exemples, nous présentons la simulation de la propagation d’une fissure dans un matériau fragile ainsi que le développement d’une bande de cisaillement dans un matériau ductile. Les codes numériques associés aux formulations présentées dans ce travail ont été générés par l’outil de programmation symbolique et d’optimisation de code AceGen. Les performances des éléments sont présentés à travers un grand nombre d’exemples numériques réalisés à partir du code AceFem<br>The dissertation deals with limit load and limit ductility analysis of structures by the finite element method. When structure is at its limit load, several structural components behave inelastically, while in the critical parts of the structure, due to localization of inelastic strains, failure of material appears. Localized effects in brittle materials are related to appearance and formation of a large (macro) crack, while failure in ductile materials is governed by localized shear bands. The study of limit load is thus related to modeling both standard inelastic material effects, as well as modeling of localized failure of material, often reffered to as material softening. Standard inelastic material effects are in this work described with elastoplastic, elastoviscoplastic and nonlinear elastic material models. All the material models are defined at the level of stress-resultants. Several mathematical approaches and numerical algorithms for modeling localized effects are at hand, but they are often inefficient or inaccurate. Therefor, we use an up-to-date approach, based on a finite element method with embedded discontinuity. We derive new finite element formulations with a quite complex kinematics of the basic elements, as well as rather complex description of discontinuous displacement fields. We derived several finite element formulations for analysis of different structural components. First we present a finite element for limit load analysis of reinforced concrete plates. Stress-resultant elastoplastic and elastoviscoplastic plate finite element formulation along with a unified computational procedure that covers both formulations are presented next. Further, a nonlinear shell finite element, based on a two-surface yield function, that includes both isotropic and kinematic material hardening is presented. The last two finite elements derived in this work are intended to model the localized failure in planar beams and 2D solids. The embedded discontinuity in rotations was built into elastoplastic Euler-Bernoulli beam finite element, and a procedure, based on a precomputed analysis of a part of a structure, by using a refined numerical model, is proposed to obtain the beam constitutive model parameters. Finally, we derive an elastoplastic quadrilateral two-dimensional finite element formulation with embedded strong discontinuity, whose kinematics can model linear jumps in both normal and tangential displacements along the discontinuity line. Numerical simulations show, that the derived finite elements, along with the accompanied numerical algorithms, are an efficient and a rather robust tool for limit load and failure analysis of structures. Among other examples, we present a simulation of crack growth in brittle material and a simulation of shear band failure in ductile material. All the computer codes of the finite element formulations presented in this work have been generated through the symbolic programming of the finite element computer code and the expression optimization in AceGen computer program. The performance of these elements has been presented in numerous numerical examples, all performed by the AceFem computer program
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Wildman, Craig B. E. (Craig Bradley Edward) 1987. "High load limits of the controlled autoignition engine." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50578.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.<br>Includes bibliographical references (p. 153-157).<br>The controlled autoignition (CAI) engine is an engine concept that features very low soot and NOx emissions while achieving diesel-like efficiency. The CAI combustion process is characterized by a fast, volumetric burn of a premixed fuel and air mixture that is heavily diluted with either excess air or burned gas. One problem that limits the engine's introduction into the market is that the rate of combustion can be fast to the point that it is very loud and is destructive to the mechanical components of the engine. The nature of this problem is akin to spark-ignition knock and presents a high-load limit to the operating range. Misfire presents a second high-load limit. This work seeks to understand how various engine parameters affect the high-load knock limit and the high-load misfire limit of a CAI engine operating in the negative-valve-overlap mode. Valve timing, and therefore trapped residual gas fraction, turbocharging, intake air heating, and exhaust gas recirculation (EGR) are all explored for their effects on the high load limit. A single-cylinder research engine is used to assess each of these effects. 91 RON gasoline is used for all tests. The first part of the study explores the effects of boost, intake air temperature, and trapped residual fraction on the rate of pressure rise, which was used as the metric for knock, and on NIMEP. It was shown that if operation is constrained by maximum pressure rise rate (PRRmax,,), the maximum load condition always lies at the misfire limit. The dependencies of misfire on boost, intake air temperature, and residual fraction were also explored.<br>(cont.) The second part of the study examined how the use of EGR affected the high-load limit. Again, the high-load limit, constrained by maximum pressure rise rate, was maximized at the misfire limit. Varying boost and intake temperature did not materially change the high load limit because the misfire limit and the PRRmax changed simultaneously in such a way that the NIMEP at the new limit point did not change appreciably from the original value. Correlations were developed for the misfire limit, for the burn duration, and for combustion phasing.<br>by Craig B.E. Wildman.<br>Ph.D.
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Pevner, Jan. "Nadzemní parkovací dům." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226965.
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The work focuses on the design and assessment of selected structural elements of one overground floor monolithic concrete structures and staircases. All calculations are done in accordance with Eurocode 2.
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Fergenbaum, Mitchell Alan. "Development of safety limits for load carriage in adults." Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/855.
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Imamovic, Ismar. "Ultimate load limit analysis of steel structures accounting for nonlinear behaviour of connections." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2373/document.
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Cette thèse traite de l'analyse limite des structures de châssis en acier, qui s'utilise souvent comme la structure principale de support des bâtiments. La structure du cadre en acier est caractérisée par une réponse très ductile et un grand potentiel pour dissiper l'énergie, ce qui est crucial pour la résistance par rapport aux tremblements de terre. La ductilité dans la réponse de la structure est la cause du comportement du matériau lui-même et du comportement des connexions entre les éléments de la structure. Les connexions entre les poutres et les poteaux peuvent influencer de manière significative la réponse de la structure du cadre en acier, parfois jusqu'à 30%. L'idée est de intégrer le comportement des connexions par les éléments de poutres qui seront situés dans les coins du cadre et la modélisation du reste serra fait avec des éléments de poutres non-linéaires qui décrirons le comportement des poutres en acier. Cette recherche est composée de deux parties. La première partie est consacrée au comportement des connexions structurelles, la deuxième partie présente le développement de l'élément fini du faisceau non linéaire capable de représenter le comportement ductile d'un élément de la structure en acier. Dans la première partie de la thèse, nous définissons la procédure d'identification des paramètres constitutifs pour le modèle couplé de plasticité-dégâts avec dix-huit inconnus. Ce modèle constitutif est très robuste et capable de représenter une large gamme de problèmes. La procédure définie a été utilisée dans la préparation de tests expérimentaux pour trois types de connexions en acier structuré. Les tests expérimentaux ont été effectués pour deux cas de charge. Pour la première, la charge a été appliquée dans un sens avec les cycles de chargement et de déchargement. À partir des mesures expérimentales, nous avons conclu que le modèle de plasticité peut bien représentée le comportement de la connexion structurale. Paramètres constitutifs ont été déterminés à partir des résultats de l'expérimentation, on a utilisé une poutre géométriquement exacte avec la loi bilinéaires renforcement du matériel et la loi linéaire pour le ramollissement. Également, on a effectué des essais expérimentaux de deux types de raccords en acier en cas de chargement cyclique. Les données mesurées montrent que le modèle de la plasticité n'est pas assez bon pour décrire le comportement de connexion pour ce type de charge. A savoir, en raison de changements du sens de l'application du chargement, les connexions montrent moins de rigidité, qui peut être décrite avec un modèle constitutif de dommages. Pour cette raison, nous avons développé un nouveau modèle plasticité-dommages qui est capable d'inclure le phénomène mentionné ci-dessus. A la fin de cette section est faite l'identification des paramètres constitutifs. La deuxième partie de la thèse de doctorat est composé de formulations théoriques et la mise en œuvre numérique des faisceaux géométriquement exacte. La réponse de durcissement de la poutre comprend l'interaction entre les forces de la section résultant du stress (N, T et M), et la réponse de ramollissement est définit par la loi non linéaire. Ce type d'élément fini de poutre est capable de décrire le comportement ductile des structures en acier et inclure les effets du second ordre, qui sont très importantes pour l'analyse ultime des structures de cadre en acier. L'élément fini développé de poutre géométriquement exacte et les lois définies de liaison de comportement dans la construction en acier, offrant la possibilité d'une analyse de haute qualité des structures en acier. En utilisant les modèles de poutre proposé et la méthodologie de modélisation des structures de châssis en acier, il est possible de déterminer une distribution réaliste des forces de section transversale , y compris la redistribution due à la formation de rotules plastiques<br>This thesis deals with the ultimate load limit analysis of steel frame structures. The steel frame structure has a very ductile response and a large potential to dissipate energy, which is crucial in the case of earthquakes. The ductility in the response of the structure comes from the behavior of the material itself and the behavior of the semi-rigid structural connections. The semi-rigid connections between beams and columns can significantly influence the response of the structure, sometimes up to 30%. In this thesis, we propose a methodology for modeling steel frame structures with included connection behavior. The idea is to model the behavior of the structural connections by the beam elements positioned in the corners of the steel frame structure. Other members of the steel frame structure, steel beams, and columns, will be modeled with nonlinear beam elements. This research consists of two parts. The first part deals with the behavior of the structural steel connections. In the second part, we present the development of the nonlinear beam element capable of representing the ductile behavior of steel structural elements, beams and columns. In the first part of the thesis, we define constitutive parameters identification procedure for the coupled plasticity-damage model with eighteen unknowns. This constitutive model is very robust and capable of representing a wide range of problems. The identification procedure was used in the preparation of experimental tests for three different types of structural steel connections. The experimental tests have been performed for two load cases. In the first, the load was applied in one direction with both the loading and unloading cycles. From the experimental measurements, we have concluded that the response of the experimental structure can be represented by the plasticity model only because no significant change in the elastic response throughout the loading program was observed. Therefore, we have chosen an elastoplastic geometrically exact beam to describe connection behavior. The hardening response of the beam is governed by bilinear law, and the softening response is governed by nonlinear exponential law. The identification of the parameters has been successfully done with fifteen unknown parameters identified. The two types of the experimental structures were also exposed to the cyclic loading. Measured experimental data shows complex connection behavior that cannot be described by the plasticity model alone. Namely, after changing load direction stiffness of the connection decreases. This suggests that the damage model should be incorporated in the constitutive law for the connections behavior as well. Therefore, we propose a new coupled plasticity-damage model capable of representing the loss in the stiffness of the connection with the changing of the load direction. At the end of this part, we also give the constitutive parameters identification for the proposed model. The second part of the thesis deals with the theoretical formulation and numerical implementation of the elastoplastic geometrically exact beam. The hardening response of the beam includes interaction between stress resultant section forces (N, T and M), and the softening response of the beam, which is governed by the nonlinear law. This type of the beam element is capable of representing the ductile behavior of a steel frame structure, and it takes into account second order theory effects. Performed numerical simulations show that the proposed geometrically nonlinear beam element is very robust and is able to provide a more precise limit load analysis of steel frame structures. By using proposed methodology for modeling steel structures, we are able to obtain the real distribution of section forces, including their redistribution caused by forming of the hinges and the connections behavior
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Scaringe, Robert J. (Robert Joseph). "Extension of the high load limit in the Homogeneous Charge Compression Ignition engine." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50585.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.<br>Includes bibliographical references (p. 120-121).<br>The Homogeneous Charge Compression Ignition (HCCI) engine offers diesel-like efficiency with very low soot and NOx emissions. In a HCCI engine, a premixed charge of air, fuel and burned gas is compressed to achieve autoigntion. Combustion occurs throughout the chamber volume resulting in short overall burn duration. This short burn duration can cause excessively high pressure rise rates which lead to unacceptable engine noise and potentially reduced engine life. To combat this high pressure rise rate the engine must be operating with significant diluent, either excess air or burned exhaust gas. However this high level of dilution limits the specific output of the HCCI engine to levels far below spark ignition or diesel engines. The high load limit is a major challenge for the HCCI engine. This study utilized a single cylinder research to examine the high load limit and possible methods to extend it. The details of the high load limit were first explored across a range of intake temperatures, boost pressures, trapped residual fractions, equivalence ratios and external EGR ratios for a gasoline fueled HCCI engine. A significant finding was that the high load limit always occurs at the misfire limit and that for a given pressure rise rate constraint, the high load limit occurs at lowest possible intake pressure and trapped residual fraction needed to prevent misfire. A possible means to allow operation at higher boost pressures is to utilize cooled external EGR or to reduce the intake temperature. For a given burn fraction, increasing the EGR rate or reducing the intake temperature provided reduced MPRR.<br>(cont.) However with these changes, the misfire limit also shifted such that the value of the maximum load does not materially change. Thus boosting coupled with EGR or intake temperature reduction can not be used to significantly extend the high load limit. A correlation was developed for the burn duration. Multi-zone combustion simulations were used to confirm the form of this correlation. The multi-zone based correlations were then used to quantitatively examine the potential of thermal stratification as a means to extend the high load limit. It was shown that for a doubling of the width of the in-cylinder temperature distribution, a 30% increase in the high load limit is possible.<br>by Robert J. Scaringe.<br>Ph.D.
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Parke, Gerard Andrew. "The behaviour of space trusses incorporating novel compression members." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/934/.
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Meek, Caroline. "The influence of biaxial loading on the assessment of structures with defects." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/the-influence-of-biaxial-loading-on-the-assessment-of-structures-with-defects(b0a7d8ff-5bc5-4463-b07d-0e3b00f85b2e).html.
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Assessments of structures with postulated or existing defects are generally carried out using standards and engineering assessment procedures. Assessments of this type involve comparing an applied force, in this case the crack driving force, with a material property, which in this case is the material's resistance to fracture, its fracture toughness. The crack driving force J can be calculated directly or implicitly by using a failure assessment diagram. Assessments can be based on either the initiation of the growth of a crack or, when dealing with ductile fracture, on an amount, e.g. 2 mm, of ductile tearing. Material fracture toughness values are obtained by testing high constraint specimens such as deeply cracked compact tension specimens and single edge notched bend specimens under uniaxial loading conditions. The high constraint of the test specimens provides conservative measurements of the fracture toughness for most applications. However, this assumption of conservatism is not necessarily applicable where there are biaxial loading conditions. The literature concerning assessments of such components mainly discusses whether uniaxial loading conditions provide conservative estimates of fracture toughness. Crack driving forces under biaxial loading can be overestimated, leading to a loss of conservatism. Conversely, biaxial loading could be beneficial and thus an approach that is consistently conservative has implications for the cost and time involved in the consequences of prematurely assessing or predicting the failure of a structure or component. This research considers the effects of biaxial loading on all the parameters involved in the integrity assessment of structures, components and specimens with defects. These parameters include the crack driving force, material fracture toughness, internal stresses and limit loads. It will address their relative effects on the determination of failure when compared with the assumption of uniaxial loading. The methods used will be analytical, using the equations and theories of standard solid mechanics, fracture mechanics and existing advice in R6 and the literature, and numerical using finite element analyses. Experimental, analytical and numerical work in the literature will be assessed and discussed and their outcomes compared with the findings of this research. The overall aim is to provide more explicit advice on the assessment of defects in components under biaxial loading in the R6 procedure.
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Balhar, Martin. "Patrové garáže." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392201.
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This thesis deals with design of steel structure multi-storey garage. It is the five-storey steel structure of rectangular plan. The construction is designed for the city of Olomouc. Static calculation is solved by a combination of manual calculation and calculation using software Scia engineer 18. There are the following main load bearing structural elements designed and examined in the structural analysis: truss, purlin, bracing, column, composite beam, joints, foot and anchoring. Thesis includes drawing documentation
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Roberts, Lance Alan Misra Anil. "Reliability-based design and analysis of deep foundations at the service limit state." Diss., UMK access, 2006.
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Thesis (Ph. D.)--School of Computing and Engineering and Dept. of Geosciences. University of Missouri--Kansas City, 2006.<br>"A dissertation in engineering and geosciences." Advisor: Anil Misra. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Jan. 29, 2007. Includes bibliographical references (leaves 200-206). Online version of the print edition.
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Gandiaga, Lorehana. "Serviceability limits and economical bridge design." Laramie, Wyo. : University of Wyoming, 2009. http://proquest.umi.com/pqdweb?did=1939207291&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Bian, Jian. "Ultimate flexural limit states analysis of prestressed concrete sleeper." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/63660/1/Jian_Bian_Thesis.pdf.
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Railway is one of the most important, reliable and widely used means of transportation, carrying freight, passengers, minerals, grains, etc. Thus, research on railway tracks is extremely important for the development of railway engineering and technologies. The safe operation of a railway track is based on the railway track structure that includes rails, fasteners, pads, sleepers, ballast, subballast and formation. Sleepers are very important components of the entire structure and may be made of timber, concrete, steel or synthetic materials. Concrete sleepers were first installed around the middle of last century and currently are installed in great numbers around the world. Consequently, the design of concrete sleepers has a direct impact on the safe operation of railways.
The "permissible stress" method is currently most commonly used to design sleepers. However, the permissible stress principle does not consider the ultimate strength of materials, probabilities of actual loads, and the risks associated with failure, all of which could lead to the conclusion of cost-ineffectiveness and over design of current prestressed concrete sleepers. Recently the limit states design method, which appeared in the last century and has been already applied in the design of buildings, bridges, etc, is proposed as a better method for the design of prestressed concrete sleepers. The limit states design has significant advantages compared to the permissible stress design, such as the utilisation of the full strength of the member, and a rational analysis of the probabilities related to sleeper strength and applied loads.
This research aims to apply the ultimate limit states design to the prestressed concrete sleeper, namely to obtain the load factors of both static and dynamic loads for the ultimate limit states design equations. However, the sleepers in rail tracks require different safety levels for different types of tracks, which mean the different types of tracks have different load factors of limit states design equations. Therefore, the core tasks of this research are to find the load factors of the static component and dynamic component of loads on track and the strength reduction factor of the sleeper bending strength for the ultimate limit states design equations for four main types of tracks, i.e., heavy haul, freight, medium speed passenger and high speed passenger tracks.
To find those factors, the multiple samples of static loads, dynamic loads and their distributions are needed. In the four types of tracks, the heavy haul track has the measured data from Braeside Line (A heavy haul line in Central Queensland), and the distributions of both static and dynamic loads can be found from these data. The other three types of tracks have no measured data from sites and the experimental data are hardly available. In order to generate the data samples and obtain their distributions, the computer based simulations were employed and assumed the wheel-track impacts as induced by different sizes of wheel flats. A valid simulation package named DTrack was firstly employed to generate the dynamic loads for the freight and medium speed passenger tracks. However, DTrack is only valid for the tracks which carry low or medium speed vehicles. Therefore, a 3-D finite element (FE) model was then established for the wheel-track impact analysis of the high speed track. This FE model has been validated by comparing its simulation results with the DTrack simulation results, and with the results from traditional theoretical calculations based on the case of heavy haul track. Furthermore, the dynamic load data of the high speed track were obtained from the FE model and the distributions of both static and dynamic loads were extracted accordingly. All derived distributions of loads were fitted by appropriate functions. Through extrapolating those distributions, the important parameters of distributions for the static load induced sleeper bending moment and the extreme wheel-rail impact force induced sleeper dynamic bending moments and finally, the load factors, were obtained. Eventually, the load factors were obtained by the limit states design calibration based on reliability analyses with the derived distributions. After that, a sensitivity analysis was performed and the reliability of the achieved limit states design equations was confirmed. It has been found that the limit states design can be effectively applied to railway concrete sleepers.
This research significantly contributes to railway engineering and the track safety area. It helps to decrease the failure and risks of track structure and accidents; better determines the load range for existing sleepers in track; better rates the strength of concrete sleepers to support bigger impact and loads on railway track; increases the reliability of the concrete sleepers and hugely saves investments on railway industries.
Based on this research, many other bodies of research can be promoted in the future. Firstly, it has been found that the 3-D FE model is suitable for the study of track loadings and track structure vibrations. Secondly, the equations for serviceability and damageability limit states can be developed based on the concepts of limit states design equations of concrete sleepers obtained in this research, which are for the ultimate limit states.
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Wright, D. S. "Enforcement policy : An economic approach to H.G.V. weight limits." Thesis, Cranfield University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383095.
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Maria, Amir Gamal. "The role of fuel in determining the high load limit of controlled auto-ignition engines." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46642.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.<br>Includes bibliographical references (p. 77-79).<br>Controlled Auto-Ignition (CAI) engines have the potential to increase fuel economy while lowering nitrogen oxide and soot emissions. One hurdle that is currently being faced is the engine's inability to operate at high loads due to a large Maximum Pressure Rise Rate (MPRR). To address this issue, this research has been focused on analytically determining the optimum fuel that can be used in a CAI engine to reduce the MPRR and extend the high load limit. The strategy is to use the fuel ignition characteristics to maximize the impact of stratification on reducing the MPRR with sequential ignitions. To quantify the impact of the selected fuel on the high load limit, the fuel's ignition delay curve under constant volume conditions, as a function of the initial concentration and temperature was used. A parametric model of the fuel chemistry was created so that different functional dependences of the ignition delay curve could be produced through adjustment of the model parameters. Then, the ignition delay curve was parameterized, and various artificial fuels were created. The artificial fuels were then tested in an engine simulation under different operating conditions and temperature distributions. The results from the engine simulations provide insight into the characteristics of the optimum fuel ignition delay time versus temperature relationship. As expected, the conclusions depend on the initial boundary conditions applied; particularly the initial cylinder temperature distribution. With a constant temperature applied to the entire charge, the MPRR is reduced when ignition occurs in the Negative Temperature Coefficient (NTC) region. When ignition occurs in the NTC region, the radical concentration in the later stages of the combustion process is reduced, which reduces the MPRR. When an initial quadratic temperature distribution is applied, different regions of the combustion chamber can ignite at different periods, hence reducing the MPRR. However, ignition in the NTC region negates this positive effect, and should therefore be avoided. The functional dependency of the ignition delay time versus initial temperature for the optimum fuel must therefore be created based on the expected initial charge temperature distribution.<br>by Amir Gamal Maria.<br>S.M.
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Pasquali, Paulo Roberto Zanella. "Análise limite de estruturas através de uma formulação em elasticidade não-linear." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/13430.
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A avaliação numérica das cargas limites (de colapso) de estruturas é obtida geralmente ou pela aplicação direta dos teoremas de análise limite junto com processos de otimização ou mediante análises incrementais, que levam em consideração o comportamento elasto-plástico do material. Entretanto, ambas as estratégias conduzem eventualmente a dificuldades numéricas, particularmente para cargas próximas à de colapso. Neste trabalho, emprega-se uma alternativa que consiste em simular assintoticamente o comportamento elasto-plástico mediante uma relação elástica não-linear. As vantagens deste tipo de formulação são a possibilidade de se lidar com leis de fluxo não-associadas e um custo computacional reduzido. A relação elástica não-linear é implementada no programa comercial de elementos finitos ABAQUS, através de uma sub-rotina externa ao programa escrita em linguagem FORTRAN. Diversos exemplos de estruturas cujos materiais são regidos pelos critérios de resistência de von Mises e Drucker-Prager são modelados, verificando-se que os resultados das cargas limites obtidas com essa formulação são muito próximos daqueles encontrados na literatura. Por fim, a relação elástica não-linear é empregada para a determinação do domínio de resistência de meios porosos, com diferentes níveis de porosidade.<br>The numerical assessment of limit loads of structures is generally achieved through the direct implementation of limit analysis theorems together with optimization processes, or through incremental analyses, which account for the elastic-plastic behavior of the material. However, both the strategies may lead to numerical difficulties, particularly when the load is close to its limit value. In this context, the alternative approach presented in this work consists in simulating asymptotically the regime of free plastic flow by means of a fictitious non-linear elastic material. One of the main advantages of this kind of formulation lies in its ability to deal with non-associated flow rules and a reduced computational cost. The non-linear elastic behavior is implemented into the finite element computational software ABAQUS, making use of an external subroutine written in FORTRAN language. Several examples of geotechnical and structural problems with materials ruled by von Mises and Drucker-Prager failure criteria are analyzed. The results obtained with this formulation prove to be very close to those obtained through analytical solutions. At last, the non-linear elastic relation is used in the determination of the resistance domain of porous media with different levels of porosity.
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Carlet, Lorenzo. "The effect of the ductility on the collapse loads: The failure of a steel roof." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8511/.
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Studio dell'effetto della duttilità sul carico di collasso: il crollo di una copertura reticolare spaziale in acciaio causato dalla compresenza di un'ingente mancanza di resistenza e duttilità nei collegamenti delle aste e possibili stati coattivi. Il carico di collasso nel caso di strutture a bassa duttilità dipende dalla presenza di stati coattivi dovuti a imperfezioni di realizzazione o cedimenti vincolari della struttura in esercizio.
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Knudsen, Eirik, and Karsten Lie Skadal. "Basalt Reinforced Concrete in Load Carrying Structures : Structural Behaviour in the Serviceability and Ultimate Limit State." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18795.
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Reforcetech AS is about to develop, and has just started, the manufacturing of basalt fibres for reinforcing concrete structures. Contrary to steel bars, the basalt reinforcement is non-corrosive, non-conductive, and non-magnetic. Basalt fibres can be delivered both as reinforcement bars and as fibre reinforcement, known as Minibars. This report evaluates the use of both basalt rods and basalt fibres in load carrying concrete beams. As a part of this report, six beams were tested; three pairs with different reinforcement setup. The first pair was lightly reinforced with three Ø10,1 bars as longitudinal reinforcement. The second pair was similar to the first, but with 0,75 vol% added basalt fibres. The third, and last pair, was more heavily reinforced; seven reinforcement bars and 0,75 vol% added basalt fibres. All beams had dimensions of 200x300x4000 mm. With this setup, the effects of basalt fibres could be examined as well as the influence of an increased reinforcement area. The test results were compared to available design rules.
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Cordero, Raymundo. "Limit state analysis : adaptive finite element upper and lower bound approach to the evaluation of the limit load of a Von Mises rigid-plastic material body in plane stress." Thesis, Swansea University, 2005. https://cronfa.swan.ac.uk/Record/cronfa42326.
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A new approach to the computation of the Limit load of a Von Mises rigid-plastic material structure modelled in plane stress is assessed. Most international design codes require the engineer to establish the safety of a structure for a given set of design loads under the so-called limit state conditions. The limit state represents the failure point at which the structure begins to exhibit unbounded deformations. Under limit state conditions, the deformation of the solids tend to concentrate on thin failure bands, known as slip-lines. This makes the finite element analysis a challenging task as the mesh needs to be adapted to capture these bands accurately. In order to achieve this, an adaptive technique is required whereby the error produced in each finite element is measured and if required the element is subdivided automatically. In order to measure this error both an upper and lower bound of the exact solution need to be evaluated. In this thesis, a novel technology to obtain the lower bound is derived and implemented together with mesh adaptivity technology. A lower bound is found from a state of stresses in equilibrium with the external forces. The proposed technique obtains such equilibrated state using the stresses obtained during the upper bound evaluation. These stresses, although not strictly in equilibrium, can be balanced using procedures available in the literature. The present aim of the research project is to develop numerical technology based on the finite element method to calculate the limit state of two-dimensional solids in plane stress. The upper bound theorem of limit analysis is implemented by means of a Lagrangian optimization technique solved by the Newton-Raphson method with Line Search. A control parameter to deal with the singularity of the tangent stiffness matrix due to the yielding condition is used along the range of admissible rate of deformations for a rigid-plastic material. The lower bound theorem is then applied by performing a technique to equilibrate the interelement tractions, kinematically solving a sequence of local problems using the equilibrated tractions as an updated load input, which lets us determine the elementwise contribution to both the upper and lower bounds. An adaptive technique is then implemented, based on the elemental contributions to the difference between the upper bound and the lower bound of the collapse multiplier. Both non-adaptive and adaptive results are evaluated. Results show a good performance of the solution technique, both in comparison with well known plane stress bound values and also in the graphical output obtained in the form of refined regions which describe the occurrence of slip-line patterns and/or localized yielding regions.
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Decker, Brandon T. "In-Plane Lateral Load Capacities of Vertically Oriented Interlocking Timber Panels." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5304.
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The Vertically Oriented Interlocking Timber (VOIT) panel is a new solid wood panel similar to Interlocking Cross Laminated Timber (ICLT) and the more commonly known Cross Laminated Timber (CLT). Like ICLT, VOIT panels use timber connections instead of the adhesives or metal fasteners common to CLT. The difference of VOIT is the orientation of the layers. Where CLT and ICLT panels alternate the orientation of each layer, VOIT panels orient all the layers in the same direction. The vertically oriented layers are then attached to one another by smaller horizontal dovetail members.Two types of VOIT panels were provided to be tested for in-plane lateral loading. Type I had three rows of horizontal dovetail members connecting the layers and Type II had four rows of dovetail members as well as two diagonal members to provide stiffness. Two panels of each type were provided, measuring 8 ft. wide, 8 ft. tall, and 13.75 in. thick. Each panel was disassembled after monotonic lateral in-plane loading to determine possible failure modes. Testing results suggest the VOIT panels to be comparable in shear strength to other wood shear walls, including light frame, CLT, and ICLT walls. A two-part analytical model was created to determine the deflection of the wall when loaded as well as the shear strength of the wall. The model predicted deflection and wall strength reasonably well. Due to the small sample size, additional testing is necessary to confirm the results of the Type I and Type II VOIT panels. Additional testing with more variations of the panel and member geometries is also needed to validate the scope of the model.
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Tamimi, Ala. "Voltage stability limits for weak power systems with high wind penetration." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/13100.
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Doctor of Philosophy<br>Department of Electrical and Computer Engineering<br>Anil Pahwa<br>Shelli K. Starrett<br>Analysis of power system voltage stability has practical value in increasing wind penetration levels. As wind penetration levels increase in power systems, voltage stability challenges arise due to locating wind resources far away from load centers. This dissertation presents several different voltage stability methods for sizing new wind farms. Power system wind penetration levels depend on the available voltage stability margins (VSMs) of the existing power system and system load characteristics. Three new iterative methods have been developed to maximize wind penetration level in weak power systems based on systems’ VSMs. The first two methods use an iterative approach for increasing the size of each wind farm until reaching the collapse point. Wind farms with less negative impact on system VSMs are sized larger than others. A third wind farm sizing method has been developed using modal analysis in conjunction with the traditional voltage stability method (Q-V method). Wind farms are placed at buses in the power system which have the lowest negative impact on voltage instability modes (strong wind injection buses). By placing the wind farms at the strongest wind injection buses, higher amounts of wind power can be injected into the power system. To further increase wind penetration in weak power systems, two additional techniques are introduced and applied to the western Kansas power system. The first technique uses modes of voltage instability to place voltage support equipment like static var compensators at locations in the power system where they provide the needed reactive power support for increasing levels of wind penetration. The second technique uses the fact that wind patterns at a wind farm site may rarely allow the wind farm to produce its maximum capacity during the peak loading hours. Wind farm maximum sizes can be increased above their maximum voltage stable size limit without driving the power system into becoming voltage unstable. Preventing voltage collapse for the additional increases in wind farm sizes is accomplished by disconnecting some wind turbines inside the wind farm during critical times to reduce its power output to a voltage stable level.
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Alkan, Olsson Johanna. "Setting limits in nature and the metabolism of knowledge : the case of the critical load concept /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/arts274s.pdf.
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Rudani, Manan Sureshbhai, and Hampus Ring. "Strength Analysis of Deployable Hangar." Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-179926.
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It is of interest to investigate extended usability of Saab’s Deployable Aircraft Maintenance facility(DAM) with respect to Eurocode standards. One of the features of the deployable hangar is that it shouldcomply with the structural strength standards for permanent buildings which requires compliance withEurocodes.Eurocodes are European standards which deals with the development of building and structural design.Compliance with Eurocodes works as a proof of requirement for mechanical strength, stability andsafety of structures. The Eurocodes were created by the European Committee for Standardization withthe intent to simplify technical obstacles and enable trade within Europe and elsewhere.The thesis has resulted in the creation of a Finite Element Model (FE-Model) of the deployable hangar,for which different loading combinations have been applied. From the FE-results, trade-off curves havebeen generated that show the effect that the different loading conditions have on the differentcomponents of the hangar. This is done for the current configuration of the hangar and for differentproduct variants. The analysis includes the effects of increased load levels.From the trade-off curves it is possible to see to what extent the hangar can withstand increased load.This is being measured with a Eurocode ratio. It has been found that the Eurocode ratio is directlydependent on increase of loads i.e. increased loads give a linear increase in Eurocode ratio for most ofthe components studied. The product variants consists of different lengths of the hangar. From the studyit has been found that adding or removing sections does not have a substantial effect on the strength ofthe hangar and the Eurocode ratio mostly remains constant. In addition the most critical componentshave been found and design suggestions have been proposed to improve the strength of the hangarwithin compliance with Eurocodes.
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Erguner, Kamil. "Analytical Examination Of Performance Limits For Shear Critical Reinforced Concrete Columns." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611220/index.pdf.
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Most of the older reinforced concrete (RC) buildings have columns that are deficient
when the current code requirements are considered. Therefore, performance of the columns
determines the performance of the structure under the effects of earthquake induced lateral
loads. It is recognized that no provision is proposed in TEC2007 to estimate the failure type
called flexure-shear. Behavior of columns having probability of failing in flexure-shear
failure mode is mostly underestimated by TEC2007 procedures. In addition, failure type
classification of columns performed according to the linear and nonlinear procedures of
TEC2007 needs to be examined with respect to the test results to cover all failure types
including flexure-shear failure in order to lead the engineers develop economical and
realistic retrofit solutions.
In this study, different methods are explored to obtain reliable estimates for the
performance of code deficient shear critical RC columns. Special considerations are given to
Axial-Shear-Flexure interaction (ASFI) approach due to its mechanical background.
After examination of different approaches, ASFI method with proposed
modifications was selected as the most reliable model and lateral load-displacement analyses
were performed on a database of shear critical columns. Findings were compared with the
estimations of the nonlinear procedure given in Turkish Earthquake Code (TEC2007) for
database columns. In addition, drift capacity equations and simplified safe drift capacity
equations are proposed in light of statistical studies on the selected column specimens.
In the last part of the study, performance evaluation of columns according to
nonlinear procedures of FEMA 356, TEC2007, ASCE/SEI 41 update supplement, and
EUROCODE 8 were conducted.
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Jacobs, Cornelius Gregorius. "Vragrangskikkings ter voorkoming van asmassalasgrens-oorskryding deur padkarweiers in Suid-Afrika." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/19948.
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Thesis (PhD)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Road Tra c legislation prescribes constraints on the forces/loads which vehicles may
exert on the road at contact surfaces or load points. These constraints have bearing on
speci c contact surfaces or groups of contact surfaces. The constraints are in the form of
maximum force values and maximum ratios, which may exist between forces.
The forces exerted by a vehicle on the road is determined by a combination of the vehicle's
own mass, dimensional characteristics, and the mass and position of its cargo. The mass
and position of the cargo can be modelled by only considering its centroid. The centroid's
position is linked to a certain cargo arrangement. It is necessary, in terms of legal constraints,
to distinguish between legally permissable- and non-permissable arrangements.
Methods are proposed in this dissertation to determine the borders for the position of
the centroid according to cargo-mass, for a variety of vehicle con gurations.
The determination of borders for the position of the centroid is the result of a three part
process. Firstly, the legal limits are translated to mathematical inequalities that must be
satis ed for the forces at contact surfaces. Secondly, conservative parametric estimates
for the forces, in terms of the position and the mass of the centroid of a given vehicle,
must be derived. Finally these estimates are incorporated into the load constraints and
an enclosed permissable area for the centroid is found. These position constraints are
suitable inputs to solution methods of various cargo arrangement problems.
Linear programmes which can solve certain general arrangement problems by utilising the
position constraints on the centroid, were successfully developed. Solutions are presented
for the arrangement of pallet-freight, as well as the arrangement of cargo units with
asymetrical centroids over the length or width of a vehicle's cargo area.<br>AFRIKAANSE OPSOMMING: Padvervoerwetgewing skryf grense op kragte/laste voor wat voertuie by kontakoppervlakke
of laspunte, op die pad mag uitoefen. Hierdie voorskrifte het betrekking op spesi
eke laspunte en groepe van laspunte. Die voorskrifte is in die vorm van maksimum
laswaardes by laspunte en maksimum ratio's wat tussen sekere laste mag bestaan.
Die laste wat 'n voertuig op die pad uitvoer word bepaal deur 'n kombinasie van die
voertuig se eie massa, dimensionele eienskappe, sowel as sy vrag se massa en posisie. Die
vrag se massa en posisie kan gemodelleer word deur slegs die massamiddelpunt daarvan
te beskou. Die massamiddelpunt se posisie word gekoppel aan 'n bepaalde vragrangskikking.
Dit is nodig om, in terme van wetlike voorskrifte, te kan onderskei tussen wetlik
toelaatbare en -ontoelaatbare rangskikkings. Metodes word in hierdie proefskrif voorgestel
waarmee daar grense vir die posisie van die vragmassamiddelpunt bepaal kan word
na gelang van die vragmassa, vir 'n verskeidenheid van voertuigkon gurasies.
Die bepaling van grense vir die posisie van die vragmassamiddelpunt is die resultaat van
'n drieledige proses. Eerstens word die wetlike beperkings herlei na wiskundige ongelykhede
waarbinne laste by kontakoppervlakke moet val. Tweedens word konserwatiewe
parametriese beramings vir die laste verkry in terme van die ligging en massa van die
vragmassamiddelpunt vir 'n gegewe voertuig. Laastens word hierdie beramings in die
lasbeperkings opgeneem om 'n afgebakende toelaatbare gebied vir die vragmassamiddelpunt
se posisie te verkry. Hierdie posisiebeperkings is geskik om as inset te dien in die
oplossingmetodes van 'n verskeidenheid van vragrangskikkingsprobleme.
Line^ere programme wat sekere algemene rangskikkingsprobleme kan oplos deur die aanwending
van posisiebeperkings op die vragmassamiddelpunt, is suksesvol ontwikkel. Oplossings
word aangebied vir die rangskikking van paletvrag, asook die rangskikking van
vrageenhede met asimmetriese massamiddelpunte oor die lengte of breedte van 'n voertuig
se vragarea.
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Figueiredo, Fabíola Tocchini de. "Caracterização do escoamento no limite de mobilização de um leito granular cisalhado por um fluido." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264086.
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Orientadores: Eugênio Spanó Rosa, Erick de Moraes Franklin<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica<br>Made available in DSpace on 2018-08-20T18:21:08Z (GMT). No. of bitstreams: 1
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Previous issue date: 2012<br>Resumo: O transporte de grãos por um fluido em escoamento é frequentemente encontrado na natureza e na indústria. Está presente, por exemplo, na erosão das margens de rios, na migração de dunas no deserto e no transporte de areia em dutos. O mecanismo de transporte se dá através da transferência da quantidade de movimento do fluido para os grãos. Quando a força exercida pelo fluido no leito granular é capaz de mover alguns grãos, mas é relativamente pequena comparada ao peso dos grãos, o escoamento não é capaz de transportar os grãos como suspensão. Forma-se uma camada móvel de grãos em contato com a parte fixa do leito, conhecida como leito móvel (em inglês, 'bed-load'). Se o fluido é um líquido, a espessura desta camada móvel é de apenas alguns diâmetros de grão. A transferência de quantidade de movimento do fluido para os grãos altera o campo de escoamento tornando o perfil de velocidades diferente do caso de leito fixo. Este trabalho está interessado em entender as mudanças que acontecem no escoamento de um líquido turbulento devido à presença de um leito granular móvel, este fenômeno é conhecido como 'feed-back effect'. Os experimentos foram realizados em um canal horizontal de seção retangular e o equipamento de medida PIV (em inglês, 'Particle Image Velocimetry') foi usado para medir o escoamento turbulento de água sobre leitos granulares fixos e móveis. Os perfis de velocidade sobre leito granular fixo e móvel foram medidos para dois diferentes tamanhos de grãos, 160 'mi'm e 360 'mi'm, para a mesma vazão, em condições próximas ao limite de mobilidade dos grãos. Esta é a primeira vez que esta perturbação é experimentalmente medida no caso de escoamento turbulento de líquidos em regime hidraulicamente liso<br>Abstract: The transport of granular matter by a fluid flow is frequently found in nature and in industry. It is present for example, in the erosion of river banks, in the displacement of desert dunes and on the transport of sand in hydrocarbon pipelines. The entraining mechanism is the momentum transfer from the fluid flow to the grains. When the forces exerted by the fluid flow on the granular bed are able to move some grains, but are relatively small compared to the grains weight, the flow is not able to transport grains as a suspension. Instead a mobile layer of grains, known as bed-load, takes place. If the fluid is a liquid, the bed-load thickness is only a few grains diameters. The momentum transfer from the fluid to the mobile layer alters the fluid flow itself, i. e., the fluid flow is different from that if the bed were static. In this work we are interested in quantifying the changes (perturbation) caused by a mobile layer of grains (granular transport as bed-load) on a turbulent liquid flow. The experiments were performed on a horizontal closed-conduit channel of rectangular cross section and a PIV (Particle Image Velocimetry) device was used to measure the turbulent water flow over fixed and mobile granular beds. The turbulent fully-developed velocity profiles over fixed and mobile granular beds were measured for two different diameter of grains, 160 'mi'm and 360 'mi'm, for roughly the same water flow rates, in conditions near the threshold of the bed-load. The spatial resolution of the measurements allows the experimental quantification of this perturbation and comparison with bed-load theories. The mean flow profiles were obtained, so that the effects of bed-load on the shear stress could be determined. This is the first time that this perturbation is experimentally measured in the case of turbulent flows of liquids<br>Mestrado<br>Termica e Fluidos<br>Mestra em Engenharia Mecânica
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Griffin, Joel Sterling. "A Numerical and Experimental Investigation of Void Coalescence Causing Ductile Fracture." Thesis, Fredericton: University of New Brunswick, 2012. http://hdl.handle.net/1882/36784.
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A series of experiments and finite-element simulations were performed in order
to assess existing void coalescence criteria and propose a new model for the coalescence of cylindrical holes in a pure metal matrix during uniaxial stretching. The finite-element simulations were performed so that various plastic limit-load models could be evaluated at each strain increment during deformation, rendering predictions concerning the farfield strains required for coalescence. The experiments were performed in order to identify the actual far-field strain at the moment of incipient coalescence for the specimen geometries considered. The cylindrical-void models of Thomason (1990) and McClintock (1966) outperformed all of the other considered models in their original states. A modified form of the Ragab (2004) plastic limit-load model is proposed in the present work and is shown to have good agreement with the experimental results. The present model accounts for ligament work-hardening and ligament orientation.
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Cetkovský, Jan. "Statický návrh nosných konstrukcí bytového domu v Praze." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265290.
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The diploma thesis is aimed for design of load-bearing structures of residental building. The designed parts of building are reinforced concrete two way slab with lintels above 1th floor, reinforced concrete two way cantivelered slab above ground floor, reinforced concrete point-supported slab below ground floor, reinforced concrete columns in basement, reinforced concrete staircase in basement and static check of loadbearing walls in ground floor. The thesis contains static design, which is provided in calculated software RFEM Dlubal 5.07. The result of static design is drawing documentation of these calculated elements.
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Mattuella, Jussara Maria Leite. "Avaliação em túnel de vento do comportamento da camada limite atmosférica em terrenos complexos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/85643.
Full textAbstract:
A estrutura do vento varia de acordo com as características do terreno e com a rugosidade da superfície terrestre, desacelerando proporcionalmente sua intensidade de acordo com a proximidade do solo, o que determina a constituição da camada limite atmosférica (C.L.A.). As características do escoamento sobre e no entorno de características topográficas obtusas tais como morros são de grande interesse em muitas aplicações, especialmente aquelas ligadas à engenharia de vento. Esta pesquisa foca a investigação da C.L.A. sobre terrenos complexos, analisando a estrutura do escoamento turbulento, a separação e a recomposição do mesmo. Para tanto, dois métodos são empregados e comparados na presente investigação para identificar a influência da orografia complexa sobre o escoamento do vento: padrões ou códigos de carga de vento e análises experimentais em túnel de vento. Nove modelos experimentais de morros isolados, sendo quatro simétricos bidimensionais, quatro simétricos tridimensionais e um assimétrico, todos com a consideração de dois tipos de terreno, categoria I – plano e categorias III-IV – medianamente rugosas são analisados. A partir de uma simulação experimental da camada limite em túnel de vento, é possível parametrizar os efeitos do vento sobre terrenos complexos (MILLER, 1995). A definição de variáveis, tais como: o perfil de velocidade do vento, a intensidade de turbulência, os efeitos topográficos na velocidade do vento constituem-se em elementos fundamentais para cálculos estruturais de edificações situadas no entorno. Foram desenvolvidas simulações experimentais no túnel de vento de camada limite Prof. Joaquim Blessmann, da Universidade Federal do Rio Grande do Sul. Na superfície do modelo assimétrico, na radial principal do mesmo, foram localizados nove perfis de medição, contendo cada um, vinte alturas de investigação. Os demais modelos tiveram como foco de análise o cume dos mesmos, também com perfis definidos nas mesmas alturas. As medições da velocidade do vento e da intensidade da turbulência foram procedidas por um sistema de anemometria de fio quente. Os dados obtidos em túnel de vento foram confrontados com expressões empíricas calculadas para os mesmos pontos segundo cinco códigos ou padrões de carga de vento, pontuando também as correlações entre os mesmos e entre estes com a norma brasileira NBR 6123 (1988). Os modelos, códigos ou padrões analisados foram: Jackson e Hunt (1975) e Davenport, Surry e Lemelin (1988), models e as normas a seguir nominadas:Norma Brasileira: cargas de vento em Edificações - NBR 6123 (1988); European Standard:Eurocode1: Basis of Design and Actions on Structures, CEN TC 250: 2002; Australian/New Zealand Standard: Minimum Design Loads on Structures, AS/NZS 1170.2: 2002; Architectural Institute of Japan AIJ: 2004; American Society of Civil Engineering Standard, ASCE 7-95 (ASCE 7-95), Minimum Design Loads for Buildings and Other Structures;National Building Code of Canada, 2005, (NRCC 2005). Além do estudo comparativo acerca da resposta estimada pelos códigos nominados, esta pesquisa constitui-se em um banco de dados de medições em pontos localizados nos morros nominados, em túnel de vento. O comparativo entre os padrões mostra a inexistência de uma harmonização entre os mesmos para a consideração dos parâmetros a serem empregues para o cálculo de cargas de vento. Estas diferenças na definição dos parâmetros básicos para o carregamento de vento em estruturas determinam grandes dificuldades na unificação de formatos recomendados na previsão das cargas de vento. Comparativamente aos dados experimentais, os padrões, em geral, mostram-se conservadores para os dois tipos de morros analisados, simétrico e assimétrico, para os dois tipos de terreno, tanto considerando-se análises em 2D ou 3D.<br>The structure of the wind varies with the characteristics of the terrain and roughness land surface, slowing its intensity proportionally according to the surrounding terrain, which determines the onset of boundary layer (ABL). The characteristics of the flow over and around topographic features such as hills are of great interest in many applications, especially those related to wind engineering. From an experimental simulation of the boundary layer wind tunnel, it is possible to parameterize the effects of wind over complex terrain (MILLER, 1995). The definition of variables, such as the profile of wind speed, the turbulence intensity, the topographic effects on wind speed are key elements in structural calculations for buildings situated around the area. This research focuses on the investigation of the ABL complex terrain conditions, analyzing the structure of turbulent flow and characterization of separation and reattachment of the flow. Experimental simulations were developed in the wind tunnel of the atmospheric boundary layer Prof. Joaquim Blessmann, Federal University of Rio Grande do Sul in nine models of hills, four symmetrical two-dimensional, four- symmetrical threedimensional and one asymmetrical, all considering two types of terrain, category I - plan and Category III-IV- moderately rough. The surface of the asymmetric model was measured in nine profiles ploted on the main radial of the hill, with twenty heights each, and the other models were examined at top of the hill. The measurements were performed with a system of hot wire anemometry to measure the wind velocity and intensity of turbulence. The identification of the data obtained in the wind tunnel were confronted with empirical expressions for the same points, in order to establish the correlations between patterns and among these with NBR 6123 (1988). Two models and five codes of wind loads are analyzed: Jackson and Hunt (1975) and e Davenport, Surry e Lemelin (1988) Models and Brazilian Association of Technical Standards: Wind Load on Buildings, NBR 6123 (1988); European Standard: Eurocode1: Basis of Design and Actions on Structures, CEN TC 250: 2002; Australian/New Zealand Standard: Minimum Design Loads on Structures, AS/NZS 1170.2: 2002; Architectural Institute of Japan AIJ: 2004; American Society of Civil Engineering Standard, ASCE 7-95 (ASCE 7-95), Minimum Design Loads for Buildings and Other Structures; National Building Code of Canada, 2005, (NRCC 2005) codes. This study focuses not only the comparison of the response estimated by international codes nominees, but also a data bank of wind tunnel data to validate this tool based on empirical expressions. The comparison of the patterns shows a lack of consideration for international harmonization of the parameters to be employed for the calculations of wind loads. These differences in defining the basic parameters for the wind loading on structures determines difficulties to unify the formats recommended in the prediction of wind loads. Compared to the experimental data, the patterns will generally show up conservative for both types of mounts analyzed, symmetrical and asymmetrical, for both types of terrain, both considering 2D or 3D.
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Wu, Fei. "Ultra-Low Delay in Complex Computing and Networked Systems: Fundamental Limits and Efficient Algorithms." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu155559337777619.
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Richtrová, Pavla. "Obchodní galerie." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227865.
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The aim of this theis was to design of load-carrying steel structure of shopping mall in two variations. Geometric proposal and examination of structural element was made for both of variations. Then one variant was selected for detailed elaboration of details and drawings.
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Čožík, Martin. "Monolitická nádrž ČOV." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240045.
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The thesis deals with the design and assessment of monolithic reinforced concrete structures tanks and wastewater treatment plants in accordance with applicable standards and drafting drawings. The tank is divided into individual solved parts: base plate, walls and ceiling plate. These parts are designed according to the ultimate limit states and serviceability. Resolves an assessment of the foundation structure according to the second geotechnical categories.
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Libiger, Martin. "Lávka pro pěší přes řeku Labe." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227573.
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The thesis deals with a design of the river Labe bridging in the city Hradec Kralove. In order to make option for cyclists and pedistrians to cross between shores. There were made three design variants. For detailed solution curved twin-arm arched structure was chosen. The aim of the thesis was design and assessment of Bering strucutre of the footbridge according ultimate limit states and serviceability limit state given by valid Eurocodes.
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Kudrna, Jan. "Návrh nosné konstrukce ŽB objektu garáží." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-239994.
Full textAbstract:
The diploma thesis deals with the design and assessment of reinforced concrete structure supporting two-storey building of the underground garage for cars. In the space above the garage is designed open area with public space. The project was designed especially outer water-impermeable construction method white bath and a base plate and a perimeter wall. The structure was designed as a comprehensive model. Computing analyzed by finite element method. All selected elements were assessed at the ultimate limit state and limit state, namely to limit state of cracking load and forced stress.
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Doležal, Martin. "Čistička odpadních vod." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226429.
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This thesis deals with the design and static assessment of a concrete part of a sewage treatment plant. Specifically, the calculation and assessment of the base plate, external walls, internal walls and ceiling slabs, elaboration of shape and reinforcement drawings of selected structural element. The concrete part of the Sewage disposal plant is all below ground level. Static system and the calculation of internal forces was carried out in Scia Engineer 2011 - student version.