Relevant bibliographies by topics / Cable structures / Dissertations / Theses
To see the other types of publications on this topic, follow the link: Cable structures.

Dissertations / Theses on the topic 'Cable structures'

Author: Grafiati
Published: 4 June 2021
Last updated: 3 March 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Cable structures.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Spak, Kaitlin. "Modeling Cable Harness Effects on Space Structures." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/49302.

Full text
Abstract:
Due to the high mass ratio of cables on lightweight spacecraft, the dynamic response of cabled structures must be understood and modeled for accurate spacecraft control. Models of cable behavior are reviewed and categorized into three major classes consisting of thin rod models, semi-continuous models, and beam models. A shear beam model can predict natural frequencies, frequency response, and mode shapes for a cable if effective homogenous cable parameters are used as inputs. Thus, a method for determining these parameters from straightforward cable measurements is developed. Upper and lower bounds for cable properties of area, density, bending stiffness, shear rigidity, and attachment stiffness are calculated and shown to be effective in cable models for natural frequency prediction. Although the cables investigated are spaceflight cables, the method can be applied to any stranded cable for which the constituent material properties can be determined. One aspect unique to spaceflight cables is the bakeout requirement, a heat and vacuum treatment required for flight hardware. The effect of bakeout on spaceflight cable dynamic response was investigated by experimentally identifying natural frequencies and damping values of spaceflight cables before and after the bakeout process. After bakeout, spaceflight cables showed reduced natural frequencies and increased damping, so a bakeout correction factor is recommended for bending stiffness calculations. The cable model is developed using the distributed transfer function method (DTFM) by adding shear, tension, and damping terms to existing Euler-Bernoulli models. The cable model is then extended to model a cabled structure. Both the cable and cabled beam models include attachment points that can incorporate linear and rotational stiffness and damping. Cable damping mechanisms are explored and time hysteretic damping predicts amplitude response for more cable modes than viscous or structural damping. The DTFM models are combined with the determined cable parameters and damping expressions to yield frequency ranges that agree with experimental data. The developed cabled beam model matches experimental data more closely than the currently used distributed mass model. This work extends the understanding of cable dynamics and presents methods and models to aid in the analysis of stranded cables and cabled structures.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
2

Santoso, Katherina 1980. "Wide-span cable structures." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29417.

Full text
Abstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.
Includes bibliographical references (leaves 69-70).
In recent years, the application of cable structures in buildings has gained huge popularities. Although cable technology has been established since the 1950s, there is suddenly a surge in the number of its building application starting in the late 90s. This phenomenon is attributed to the recent advances in computational form finding, analysis and construction simulation, which make the design and construction of cable structures simpler and more economical. Although cable structures have been employed for different building applications, this thesis will concentrate only on the use of cable structures in wide span system. Five cable systems: simply suspended cables, pretensioned cable beams, pretensioned cable nets, tensioned straight cable nets and tensegric shells are studied for their mechanical properties and suitability for wide span uses. A case study is presented at the end of each system's description to illustrate its possible application. The paper will then conclude with a presentation of a general design methodology of a cable structure.
by Katherina Santoso.
M.Eng.
APA, Harvard, Vancouver, ISO, and other styles
3

Perreault, Simon. "Cable-driven pantographs." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/28152.

Full text
Abstract:
Cette thèse propose une nouvelle famille de pantographes, les pantographes à transmission par câbles (PTC). Les PTC sont définis comme des mécanismes permettant la reproduction, selon un facteur d’échelle préétabli, de mouvements imposés à l’effecteur maître vers l’effecteur esclave en se servant de câbles comme moyen de transmission des forces. Ils peuvent être aussi présentés comme étant la communion entre les pantographes conventionnels, mécanismes constitués de membrures rigides, et les mécanismes parallèles entraînés par câbles (MPEC). L’objectif de cette thèse étant la conception de PTC combinant fiabilité d’utilisation, sécurité et faible coût de fabrication, nous avons choisi de développer des outils permettant la conception de PTC purement mécaniques, c’est-à-dire qu’aucune composante électrique n’est nécessaire afin de transmettre les efforts entre les parties maître et esclave. Plusieurs applications peuvent être d’ailleurs envisagées pour ce type de mécanismes, soient, par exemple, la télémanipulation d’objets à l’intérieur d’environnements sensibles aux perturbations électromagnétiques causées par l’activation de moteurs électriques ou tout simplement lorsque l’accès à des sources d’énergie électrique est limité. L’utilisation exclusive de câbles entre les deux parties du pantographe apporte plusieurs avantages, mais aussi quelques inconvénients qui leurs sont inhérents. Le principal désavantage des PTC est sans contredit l’unilatéralité de la transmission des forces dans les mécanismes à entraînement par câbles. Ce dernier impose une disposition réfléchie des câbles, c’est-à-dire que ceux-ci doivent supporter l’effecteur selon toutes les directions, et un niveau minimum de tension afin de conserver la géométrie du système. En général, pour les MPEC, les moteurs électriques doivent fournir un couple et une puissance constants afin de maintenir cette tension. Nous proposons donc, dans cette thèse, l’utilisation de ressorts dans l’objectif de produire cette tension sans actionneur, laissant ainsi à l’utilisateur l’application de toute charge additionnelle (par exemple, pour vaincre la friction, l’inertie ou des forces extérieures appliquées à l’effecteur). Ce concept est validé par la conception mécanique du premier prototype de PTC plan à deux degrés de liberté (DDL) et entraîné par trois câbles. Dans le but de restreindre au minimum la dépense énergétique de l’utilisateur, nous suggérons ensuite la conception et l’utilisation de ressorts non-linéaires. Une méthodologie est ainsi développée afin de déterminer le comportement idéal de ces ressorts pour à la fois maintenir les câbles en tension et approximer l’équilibrage statique du mécanisme sur son espace de travail. Ces ressorts non-linéaires sont en fait constitués de mécanismes à quatre barres et de ressorts à couples constants. À titre d’exemple, cette technique est appliquée à la conception mécanique d’une nouvelle version du PTC plan à deux DDL et entraîné par trois câbles. Lors de la conception de tout PTC (et particulièrement pour les PTC comportant un espace de travail tridimensionnel), un second inconvénient doit être pris en compte. Ce sont les interférences mécaniques entre les différents câbles reliant un même effecteur à sa base correspondante (autant pour l’effecteur maître que l’effecteur esclave) lors de déplacements en translation, en rotation ou combinés. Par conséquent, nous proposons dans cette thèse une méthode permettant de déterminer de manière géométrique les régions d’interférences entre une paire de câbles et aussi entre un câble et une arête de l’effecteur à l’intérieur de l’espace de travail du PTC pour une orientation constante de ce dernier. Il est entre autres démontré que, pour une orientation constante de l’effecteur, ces zones d’interférences sont définies par des segments de plans et de lignes à l’intérieur de l’espace de travail. Cette méthode permet alors de prévoir, de manière exacte et très rapide, les lieux d’interférences pour un PTC donné et elle fournit un puissant outil lors de l’optimisation géométrique de ce type de systèmes. Cette technique est aussi directement applicable lors de la conception de tout MPEC tridimensionnel. Finalement, afin de déterminer une géométrie adéquate pour une application donnée, la dernière partie de cette thèse se concentre sur la conception d’un algorithme d’optimisation géométrique pour les PTC ou MPEC basé sur trois critères principaux. Le premier critère est la maximisation du volume de l’espace des poses polyvalentes (EPP) (critère bien connu dans la litérature scientifique). Les second et troisième critères sont basés sur l’espace libre de toute interférence mécanique (théorie développée dans la partie précédente de cette thèse) et ces espaces doivent être aussi maximisés. À titre d’exemple, les paramètres géométriques d’un MPEC comportant six DDL, étant entraîné par sept câbles et comportant neuf arêtes sont optimisés pour illustrer cette technique. Par la suite, une application médicale est utilisée comme deuxième exemple, soit la synthèse dimensionnelle d’un PTC à six DDL, entraîné par huit câbles et comportant dix-sept arêtes, prévu pour être utilisé à l’intérieur d’un système conventionnel d’imagerie par résonance magnétique (IRM) cylindrique permettant ainsi d’effectuer des biopsies simples sous guidage visuel.
This thesis reports the first steps toward the development of a new family of telemanipulators: cable-driven pantographs (CDPs). We define CDPs as mechanisms designed to reproduce trajectories induced from a master (input) to a slave (output) with a chosen scale factor and using cables in order to transmit corresponding forces or moments. They can also be presented as the combination of conventional pantographs, devices where rigid links are used to transmit forces between the master and the slave, and cable-driven parallel mechanisms (CDPMs). Given that the purpose of this thesis is the design of CDPs which combine reliability, safety and a low manufacturing cost, we have chosen to develop tools that allow the design of purely mechanical CDPs, i.e., no electrical component is necessary to transmit forces between the master and the slave. Several applications can be considered for this new family of pantographs, e.g., the telemanipulation of objects inside environments that are sensitive to electromagnetic disturbances, or simply where electrical energy access is limited. The strict use of cables between the two main components of the pantograph leads to many advantages but also to some inherent drawbacks. The main disadvantage of CDPs is without any doubt the unilaterality of force transmission in the CDPM’s cables. It imposes a reflected cables distribution, i.e., cables must support the end effector in all directions, and a minimum level of tension in order to preserve the system geometry. In general, for a CDPM, the driving electrical motors are used to produce continuous torque (and power) to maintain the cable tensions. In this thesis, we propose a methodology which relies on springs in order to produce these tensions in a purely mechanical manner, leaving to the user the application of the additional forces, i.e., those forces needed to overcome friction, produce accelerations and balance external forces applied at the end effector. This conceptual idea is validated through the design of the prototype of the first planar three-cable two-degree-of-freedom (DoF) CDP. Then, with the objective of minimizing the energy expenditure required by the user, we also suggest to compute nonlinear springs behaviours that maintain the cable tensions to a minimum level, while approximating the static equilibrium of the mechanism over its workspace. The nonlinear springs are in fact embodied as four-bar mechanisms coupled with constanttorque springs. This methodology is illustrated by its application to a modified version of the three-cable two-DoF planar CDP. When designing any CDP (in particular for CDPs with tridimensional workspace), a second drawback must be taken into account. This drawback is the possible occurrence of mechanical interferences between the different cables used to constrain the pose of the end effector from its respective base (this applies to both the master and the slave effectors) when moving in translation, in rotation or both. Thence, in this thesis, we propose a methodology for determining, in a geometrical manner, the interference regions between a pair of cables and between a cable and an end-effector edge for a given orientation within its workspace. It is shown that, for a constant end-effector orientation, these interference regions are defined by plane and line segments belonging to the CDP workspace. Then, this technique allows to determine—exactly and rapidly—the interference regions for a given CDP, and thus provides a powerful tool for optimizing the geometry of this kind of mechanisms. This methodology can also be directly applied to the design of any tridimensional CDPMs. Finally, in order to generate a suitable geometry for a given application, the last part of this thesis details an algorithm to synthesize CDP or CDPM geometries based on three main criteria. The first criterion is based on the wrench-closure workspace (WCW) (which criterion is well known in the literature), whose volume should be maximized. The second and the third ones are based on the free-interference workspace, methodology developed in the previous part of the thesis, whose volumes should also be maximized. As an example, the geometric parameters of a seven-cable nine-edge six-DoF CDPM are optimized to illustrate the relevance of the technique. Then, a medical application is used as a second example, i.e., the dimensional synthesis of an eight-cable seventeen-edge six-DoF CDP intended to be used inside a standard cylindrical magnetic-resonance-imaging (MRI) system for performing simple image-guided biopsies.
APA, Harvard, Vancouver, ISO, and other styles
4

Tan, Geoffrey E. B. "Non-linear vibration of cable-deployed space structures." Thesis, University of Cambridge, 1997. https://www.repository.cam.ac.uk/handle/1810/272328.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Oh, So-Ryeok. "Cable suspended robots control approaches and applications /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.58 Mb., 177 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3221083.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Sufian, Fuad. "Analysis and design methods for pretensioned cable net structures." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317242.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Pusey, Jason L. "Cable suspended parallel robots design, workspace, and control /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 3.60 Mb., 350 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435861.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Ndumbaro, Paul Christopher. "Cable roofs supported by reinforced concrete structures disposed to creep." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267606.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Ivanyi, Peter. "Parallel and distributed analysis and design of cable-membrane structures." Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/487.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Cinar, Simge. "Synthesis Of Silver Nanoparticles And Cable Like Structures Through Coaxial Electrospinning." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12611472/index.pdf.

Full text
Abstract:
The aim of this study is to demonstrate the possibility of production of nanocables as an alternative to the other one dimensional metal/polymer composite structures like nanowires and nanorods. There is no certain definition of nanocables
however they could be considered as assemblies of nanowires. Nanocable structure can be defined as a core-shell structure formed by a polymeric shell and a metal core that runs continuously within this shell. To produce nanocables, two main steps were carried out. Firstly, monodispersed silver metal nanoparticles to be aligned within the cable core were produced. Investigations on reduction reactions in the presence of strong and weak reducing agents and different capping agents revealed the importance of the kinetics of reduction in the production of monodispersed nanoparticles. Use of capping agents to give a positive reduction potential, resulted in the slow reduction rates that was critical for fine tuning of the final particle sizes between 1-10 nm. Hydrazine hydrate and oleylamine/ oleic acid systems were used as strong and weak reducing agents, respectively. By using weak reducing agent, monodisperse spherical silver nanoparticles with the diameter of 2.7 nm were produced. It was shown that particles with controlled diameter and size distribution can be obtained by tuning the system parameters. Secondly, particles produced as such were electrospun within the core of the polymer nanofibers and long continuous nanocables were produced. Polyvinyl pyrrolidone and polycaprolactone were used in shell part of nanocables. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), photon correlation spectroscopy (PCS), X-ray diffraction (XRD) and surface plasmon resonance spectroscopy (SPR) analyses were carried out in order to understand the mechanism by which the nanoparticles were reduced and for further characterization of the product.
APA, Harvard, Vancouver, ISO, and other styles
11

Ghoussoub, Leyla. "Analyse de quelques éléments du comportement des écrans de filets pare-blocs." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1171/document.

Full text
Abstract:
Les écrans de filets pare-blocs sont des structures complexes hétérogènes formés d'un filet métallique maintenu par des câbles, des poteaux et des haubans munis de dissipateurs d'énergie. Le filet intercepte la trajectoire du bloc rocheux et résiste à sa perforation en dissipant l'énergie cinétique de l'impact dans les différents éléments de la structure. Le problème de modélisation posé par ces structures met en jeu de nombreuses non-linéarités tant matérielles que géométriques : l'impact dynamique rapide, les grandes déformations du filet et des câbles, les glissements et les frottements (dans le filet, du filet sur les câbles ou des câbles sur les supports), la plastification du filet ou des éléments dissipateurs, ainsi qu'un très grand nombre de paramètres géométriques ou technologiques (type de filet, type de dissipateur, type d'architecture de kit).Les travaux de doctorat présentés ici proposent deux nouvelles approches pour la modélisation numérique de deux principaux éléments du comportement des écrans de filets pare-blocs : les propriétés élastiques intrinsèques des filets et l'effet rideau, c'est-à-dire le glissement du filet sur les câbles de rives. Sur le premier point, il est à noter que les recherches qui ont été consacrées jusqu'à présent à l'étude du filet se concentrent pour l'essentiel sur des typologies particulières. Dans ce travail, les propriétés intrinsèques des différentes technologies de filets sont déterminées à l'aide de la méthode d'homogénéisation des milieux périodiques discrets dans laquelle chaque filet est remplacé par une membrane homogène. Une comparaison des comportements non-linéaires des principales technologies de filets est effectuée et met en évidence des différences remarquables dans la distribution des efforts aux bords de chaque filet et les caractéristiques des déformations. Concernant le deuxième point, plusieurs études ont montré l'importance de la modélisation des câbles glissants pour reproduire le comportement réel de la structure. Dans la deuxième partie de la thèse, l'effet rideau est modélisé. Un modèle analytique de câble glissant à « n » nœuds est développé. Ensuite, ce modèle est implémenté dans un algorithme numérique mettant en œuvre une utilisation avancée du logiciel de calcul par éléments finis code-aster en statique et en dynamique. Cet algorithme est validé par des calculs analytiques et les limites de la méthode utilisée sont exposées. Enfin, des tests numériques sont conduits sur des modèles de filets en tenant compte de l'effet rideau pour évaluer l'influence du modèle développé sur les résultats. Des remarques, observations et conseils sont déduits afin d'aboutir à un outil numérique d'aide à la conception des écrans de filets pare-blocs
Soft rockfall barriers are complex structures that generally consist of a metallic net supported by steel posts and cables with brake elements. Several experimental and numerical studies have been carried out to evaluate their behaviour and a technical agreement in EU was recently established to certify these barriers based on experimental tests. Actually, manufacturers develop rockfall kits with their own technical specificities. The objective of the present work is to determine the intrinsic properties of most common nets technologies and to investigate their influence on the overall mechanical behaviour of the structure. To this end, a comprehensive comparison between the local behaviours of the different nets is first presented using equivalent homogeneous membranes. Results derived for square nets under static concentrated loading illustrate the influence of the manufacturing technology on the deflection and stresses distribution. Then, a numerical and analytical model for the so-called “curtain effect” is developed and validated. It is focused on the capacity of the proposed methodology to study and evaluate the response of the whole barrier
APA, Harvard, Vancouver, ISO, and other styles
12

Moody, Russell H. "Prototype design of cable suspended haptic interface." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176409017.

Full text
APA, Harvard, Vancouver, ISO, and other styles
13

Martins, Carolina Banki. "Estudo do efeito do escorregamento dos cabos de borda em estruturas de membranas." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-03072009-142652/.

Full text
Abstract:
Este trabalho apresenta a implementação computacional do elemento finito de cabo deslizando sem atrito, em ambiente MATLAB®, com a finalidade de modelar os cabos de borda não-aderentes das estruturas de membrana. Este novo elemento foi incluído no programa de análise de estruturas retesadas SATS, já previamente desenvolvido. Esta ferramenta é capaz de gerar resultados em deslocamentos, tensões e deformações em estruturas retesadas. São apresentadas as formulações utilizadas para a análise de estruturas de membrana, como a formulação do Método de Newton-Raphson para a resolução de equações não-lineares, as formulações do Elemento Finito de Treliça e do Elemento Finito de Cabo Ideal. É proposta, neste trabalho, a generalização da formulação do elemento de cabo de três nós para o super-elemento de cabo ideal de n nós. São desenvolvidas verificações da eficiência dos elementos finitos de cabo, por meio de exemplos simples de aplicação, nos quais são comparados os resultados obtidos com soluções analíticas. Por fim, é estudado o desempenho dos elementos de cabo, associados a elementos de membrana, por meio da análise da estrutura de cobertura do Memorial dos Povos de Belém do Pará. São comparados os resultados obtidos a partir da implementação das duas formulações apresentadas para os cabos, avaliando a influência da discretização e as diferenças em relação aos resultados obtidos em análises tradicionais usando elementos de treliça. Demonstra-se que a consideração do escorregamento nos cabos de borda é importante para a correta representação das tensões e deslocamentos em estruturas retesadas.
This work presents the implementation of a cable finite element, developed in MATLAB® environment, with the aim of modeling the cables at the boundary of membrane structures. It was added to a software named SATS (System for the Analysis of Taut Structures), which is able to give accurate results on displacements, stress and strains. This work also presents formulations used for the analysis of membrane structures, such as, the Newton-Raphson Method for solving non-linear equations, the Truss Finite Element and the Cable Finite Element. A generalization of the formulation from the three node cable element to an n-node cable super-element is proposed. The efficiency of the cable finite element has been verified by applying simple examples, comparing numerical results to analytical solutions. Finally, it has been studied the performance of these cable elements, along with the membrane finite elements, through the analysis of the membrane roof of the amphitheater of the Memorial dos Povos de Belém do Pará. The results from the implementation of both cable formulations and the traditional analysis using truss elements were compared. It has been shown that the consideration of the cable sliding is important for the accurate stress and displacements analysis.
APA, Harvard, Vancouver, ISO, and other styles
14

Bradaric, Matea, and David Desimons. "Design and Analysis of a Slanted Cable-stayed Building." Thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209912.

Full text
Abstract:
The Tubed Mega Frame (TMF) is a structural system for high-rise building developed by Tyréns AB. Compared to conventional structural systems, the TMF is a coreless system that transfers the loads through the perimeter of the building instead and in turn enables ability to support new architectural shapes and forms of buildings. This thesis covers an initial study of a high-rise building with an unconventional shape implementing the TMF system, the Cable-stayed Building, which consists of a slanted tower with a cable-supported cantilever. The study of the building was divided in to a geometrical study and a cable study. The geometrical study was carried out to gain an initial understanding of the global structural behavior by altering specific geometrical parameters. The cable efficiency in terms of total vertical forces was investigated in the cable study by comparing different cable arrangements, cable diameters and prestressing forces for a fixed global geometry. The studies were performed under linear and nonlinear static conditions using the finite element software SAP2000 and ETABS. The results from the geometrical study showed that the cable efficiency increases in terms of larger vertical cable forces with a less inclined building and longer cantilever length. In addition, the results showed significant effects of geometric nonlinearities considering P-delta for different geometric cases. Furthermore, a study of the axial forces in the mega columns indicated that the most inclined building in which no uplifting forces and barely any tension occur along the mega columns, is the 7° incline with cantilever length 73.4 m. As abovementioned, the efficiency of the cables was compared for different arrangements, cable diameter and prestressing forces. The results indicated that as the prestressing force increases, the efficiency of cables rises more for smaller cable diameter than for larger. Furthermore, the comparison of fan- and harp-shape cable arrangements showed that the latter, including three pairs of cables, gives the highest cable efficiency relative to the amount of steel required of the cantilever bracing system. Nevertheless, the study indicates that the cable forces are inherently dependent on many parameters, such as the sag effect considered in the modulus of elasticity and the stress inducing temperature, which in turn depends on cable diameter, prestressing force and cable arrangement. To conclude the study, a modal analysis showed that the Cable-stayed Building is classified as a stiff building according to the guidelines from Council on Tall Buildings and Urban Habitat. Further research on the structure could be carried out within different areas, as this thesis is only an initial study of the structure. For instance, material nonlinearities, dynamic responses of the building as well as soil structure interaction, should be investigated further.
Tubed Mega Frame (TMF) är ett bärande system för höghus utvecklat av Tyréns AB. TMF är, till skillnad från nuvarande konstruktioner, ett system utan en bärande kärna som överför laster via byggnadens perimeter istället, vilket skapar nya förutsättningar gällande arkitektoniska former på höghus. I detta projektarbete genomförs en förstudie på en byggnad med en ovanlig design, Snedkabel Byggnaden, bestående av ett lutande torn och en konsol som bärs upp av kablar.  Studien är uppdelad i en geometrisk analys och en kabel analys. Den geometriska studien syftar till att få en uppfattning om hur det globala bärande systemet beter sig genom att variera vissa geometriska parametrar. Syftet med kabel studiens är att undersöka kablarnas effektivitet genom att jämföra den totala vertikala kabelkraften med olika kabelsystem, kabeldiametrar och förspänningar för en fastställd geometri av byggnaden. Statiskt linjära och ickelinjära strukturanalyser genomfördes för båda studier i finita element programmen SAP2000 och ETABS. Resultaten från den geometriska studien visade att kabel effektiviteten ökar för en mindre lutad byggnad och en längre konsol, då kabelkrafterna ökar. Dessutom indikerar resultaten anmärkningsvärda effekter vid beaktandet av ickelinjäritet med P-delta för olika globala geometrier. En undersökning av axialkrafter i pelarna visar att den mest lutade byggnaden som inte ger upphov till upplyftande krafter och knappt några dragkrafter längs pelarna är byggnaden med 7° lutning och konsollängd på 73.4 m.   Som tidigare nämnt undersöktes kablarna effektivitet genom att jämföra olika kabelsystem, kabeldiametrar och förspänningar. Resultaten påvisade att med högre förspänningar, desto mer ökar kabeleffektiviteten för mindre kabeldiameter än större. Dessutom visade jämförelsen mellan solfjäder- och harp-systemet att harp-systemet med tre kabelpar ger stört kabeleffektivitet i relation till stålmassan för stagningen i konsolen. Krafterna i kablarna beror i sig till stor del av exempelvis elasticitets modulen med hänsyn till kablarnas nedböjning och den spänningsinducerande temperaturen, som i sin tur beror på kabeldiameter, förspänning och kabelsystem. Avslutningsvis utfördes en modalanalys som visade på att Snedkabel Byggnaden klassificeras som en styv byggnad enligt riktlinjer från Council on Tall Buildings and Urban Habitat. Ytterligare studier på strukturen kan genomföras inom olika områden, då detta är en förstudie på byggnaden. Exempelvis på vidare forskning är att ta hänsyn till materialens ickelinjäriteter, byggnadens dynamiska respons samt samverkan mellan byggnad och grund.
APA, Harvard, Vancouver, ISO, and other styles
15

Garcia-Vargas, Joel Avelino. "La précontrainte extérieure appliquée à des structures hyperstatiques." Châtenay-Malabry, Ecole centrale de Paris, 1994. http://www.theses.fr/1994ECAP0386.

Full text
Abstract:
L'étude du comportement non-linéaire des structures à précontrainte extérieure, nécessite la prise en considération des effets non-linéaires dûs au comportement des matériaux, aux effets du second ordre et au glissement des câbles sur les déviateurs. Ces effets influent sur le comportement de la structure et sur le niveau de surtension des câbles de précontrainte. La présentation de la technologie et des résultats des essais publiés sur des poutres isostatiques et hyperstatiques à précontrainte extérieure, constitue la première partie de cette étude. La deuxième partie, concerne le développement de l'élément câble de précontrainte, et en particulier externe, et l'élaboration de la modélisation du glissement des câbles sur déviateur, puis de leur intégration dans le logiciel de calcul. Pour déterminer l'influence du niveau du glissement des câbles sur déviateur, plusieurs cas de figures sont étudiés, afin de pouvoir prévoir ce qui se présente en pratique. La validation du modèle de calcul est présentée dans la dernière partie. La comparaison entre les résultats calculés et ceux des essais, a permis de tirer des conclusions sur la portée des conséquences du caractère de glissement au déviateur sur le comportement global de poutres (déformation et résistance). La représentativité de la méthode de calcul élaborée a été comparée avec d'autres méthodes développées par d'autres chercheurs
APA, Harvard, Vancouver, ISO, and other styles
16

Tibert, Gunnar. "Deployable Tensegrity Structures for Space Applications." Doctoral thesis, KTH, Mekanik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3317.

Full text
APA, Harvard, Vancouver, ISO, and other styles
17

David, Rita Aparecida. "Estudo de cestas protendidas pela técnica do meio contínuo." Universidade de São Paulo, 1995. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-24042018-113050/.

Full text
Abstract:
Neste trabalho apresenta-se um estudo do comportamento estrutural de cestas protendidas, tendo em vista a sua utilização em coberturas pênseis de grandes áreas livres. A partir da Técnica do Meio Contínuo obtêm-se as equações que permitem analisar as cestas protendidas quanto a esforços e deslocamentos. Fazem-se considerações sobre o sistema de equações encontrado visando a sua resolução mediante o emprego de programa computacional como instrumento de cálculo. Apresentam-se exemplos numéricos e os resultados são comparados com os obtidos em outros trabalhos. Fazem-se algumas considerações a respeito do projeto e do cálculo de cestas protendidas, além de algumas indicações sobre a continuidade da pesquisa.
This work presents a continuous medium method analysis of cable nets and their applications as suspended roofs for large free spans. lnitially the theory of the method is presented and later applied to get the system of differential equation that represents the problem. Finally this system is numerically solved with computational procedures. Some examples are presented and the results compared with those obtained with others methods and numerical procedures. Some analysis and design considerations and further developments in this subject are also included.
APA, Harvard, Vancouver, ISO, and other styles
18

Czerniak, Natalia Dorotea 1985. "Head involution in Drosophila melanogaster: on the role of supracellular actomyosin structures in tissue bending, spreading, and positioning." Doctoral thesis, Universitat Pompeu Fabra, 2015. http://hdl.handle.net/10803/386441.

Full text
Abstract:
Morphogenesis creates a plethora of complex shapes in plants and animals. We devote this work to the study of Drosophila head involution (HI), a late embryogenetic process, which involves complete rearrangement of the head tissues, internalization of the brain and spreading of the epidermis. We show, for the first time, the complete kinetics of HI with high spatial and temporal resolution. We describe the movements leading to the internalization of the embryonic brain, its “sculpting” by apoptosis, and cell removal by hemocytes. We then focus on the epidermal progression over the head, which can be divided into two phases: rolling and sliding. We show that both phases are powered by a supracelullar actomyosin cable. We also show that the spreading of the epidermis is spatially controlled resulting in segments of equal width being precisely positioned along the AP axis. This positional control is performed by patterned tensile forces along the epidermal layer regulated by hedgehog signaling. Our study reveals a mechanism by which genes involved in body segmentation are also regulating morphogenesis.
La morfogènesi crea una plètora de formes complexes en animals i plantes. Hem consagrat aquest treball a l'estudi de la involució del cap (head involution HI) de Drosophila, un procés embriogenètic tardiu, que implica un complet rearranjament dels teixits del cap, així com la internalització del cervell i la propagació de l'epidermis. Mostrem, pel primer cop, la cinètica completa de HI amb una alta resolució espacial i temporal. Describim els moviments que porten a la internalització del cervell de l'embrió, així com el seu “sculpting” per apoptosi i l'eliminació de cèl.lules pels hemòcits. Seguidament, hem enfocat l'estudi en la progressió de l'epidermis sobre el cap de l'embrió, essent aquest un esdeveniment que es pot dividir en dues fases: rodolament i lliscament. Mostrem que totes dues fases son impulsades per un cable d'actomyosina. També mostrem que la propagació de l'epidermis es troba espacialment controlada, tenint aquest control com a resultat la formació de segments de mateixa amplada posicionats de manera precisa al llarg the l'axis AP. Aquest control posicional és dut a terme per forces tènsils al llarg de la capa epidèrmica regulades per hedgehog. El nostre estudi revela un mecanisme pel qual els gens involucrats en la segmentació troncal regulen al seu torn la morfogènesi
APA, Harvard, Vancouver, ISO, and other styles
19

Branam, Nathan J. "A Unified Approach for Analysis of Cable and Tensegrity Structures Using Memoryless Quasi-Newton Minimization of Total Potential Energy." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502317211296101.

Full text
APA, Harvard, Vancouver, ISO, and other styles
20

Bossens, Frédéric. "Amortissement actif des structures câblées: de la théorie à l'implémentation." Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211598.

Full text
Abstract:
Cette thèse s'inscrit dans la continuation du travail de Younes Achkire, consacré au contrôle actif des ponts haubanés. Elle traite de l'implémentation d'un système de contrôle actif sur des maquettes de structures câblées. Deux types de structures sont étudiés expérimentalement: les ponts haubanés et les treillis spatiaux. Après une brève introduction sur l'usage du contrôle actif dans ces domaines, le chapitre 2 traite numériquement des mécanismes d'interaction entre le câble et la structure. Au chapitre 3, nous présentons la stratégie de contrôle que nous utilisons pour stabiliser une structure câblée: il s'agit d'un contrôle décentralisé, basé sur des paires capteur/actionneur colocalisées, placées au niveau des ancrages des câbles, chacune équipée d'un contrôleur Intégral Force Feedback. Nous présentons une théorie linéaire simplifiée permettant de dimensionner le système et de prévoir son efficacité. Elle est illustrée sur un exemple, et nous discutons de la validité de certaines hypothèses simplificatrices. Le chapitre 4 est consacré au contrôle actif des ponts haubanés. Nous y présentons 2 maquettes. La première, de petite taille (3m) représente un pylône de pont haubané en construction. Elle est équipée d'actionneurs piézoélectriques. La seconde, installée au Centre Commun de Recherche d'Ispra (Italie), mesure 30m de long, et est équipée d'actionneurs hydrauliques. Les expériences réalisées sur ces maquettes ont démontré l'efficacité du contrôle et la fiabilité de la théorie prédictive. Le contrôle du flottement des ponts est traité sur un exemple numérique. Le chapitre 5 relate nos expériences d'amortissement actif des treillis spatiaux. Deux structures ont été étudiées: une colonne en treillis équipée de 3 câbles actifs, et une structure triédrique suspendue à des cordons élastiques pour simuler l'absence de gravité, également munie de câbles actifs. Deux concepts d'actionneur piézoélectrique ont été testés. Nous avons ensuite examiné le problème de la saturation des actionneurs, et celui du contrôle actif des microvibrations (~10nm) d'une structure câblée. Le chapitre 6 conclut ce travail, en souligne les aspects originaux et donne quelques perspectives de développement.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
APA, Harvard, Vancouver, ISO, and other styles
21

Valdebenito, Galo E. "Passive Seismic Protection of Cable-Stayed Bridges Applying Fluid Viscous Dampers under Strong Motion." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/6264.

Full text
Abstract:
Terremotos recientes han demostrado la gran vulnerabilidad de algunos puentes ante movimiento fuerte. Los de tipo atirantado constituyen una tipología estructural muy atractiva, y que actualmente es empleada para muchos fines prácticos, por lo que es necesaria su protección sísmica. Entre las actuales estrategias de protección, el uso de dispositivos pasivos es la más robusta, económica y apropiada opción para mejorar el desempeño sísmico de estructuras, de entre los que destacan los sistemas de disipación de energía adicional como una buena alternativa. Debido a sus capacidades, fácil recambio y mantención, así como su buen comportamiento mecánico, los amortiguadores de fluidos viscosos son un excelente sistema de disipación de energía para proteger grandes estructuras contra eventos sísmicos intensos. Es por ello que el análisis, evaluación y comparación de la respuesta sísmica no lineal de puentes atirantados de hormigón, con y sin la incorporación de amortiguamiento viscoso suplementario, con el propósito de investigar su efectividad ante eventos sísmicos, es el principal objetivo de esta investigación aplicada.

Para alcanzar lo antes expuesto, se definieron previamente ocho modelos teóricos de puentes atirantados basados en los internacionalmente conocidos puentes de Walter [Walter, 1999], considerando variaciones del esquema de atirantamiento, nivel del tablero, tipo de tablero y espaciamiento de los cables. Como punto de partida para el análisis dinámico no lineal, se realizó un análisis estático no lineal para todos los casos. Luego, se llevó a cabo una caracterización dinámica de los puentes mediante un análisis modal. Como primera aproximación a la respuesta sísmica de los modelos, se ejecutó un análisis mediante espectros de respuesta para cada caso, con el propósito de comparar el comportamiento sísmico en función de las principales variaciones consideradas, y para seleccionar los dos modelos más representativos para ser analizados usando análisis no lineal paso-a-paso. En seguida, se analizaron las estructuras elegidas en el paso previo mediante uso de análisis temporal no lineal por integración directa, sin la consideración de amortiguamiento viscoso suplementario, y tomando en cuenta sismos de campo lejano y campo cercano. En este sentido, se aplicaron cinco eventos sísmicos artificiales para el análisis de campo lejano, y cinco eventos reales que incorporasen pulsos de velocidad de período largo para el análisis de campo cercano, según el Capítulo 3. Finalmente, el análisis de la ubicación óptima de los amortiguadores, un estudio paramétrico tendiente a seleccionar los parámetros óptimos de los mismos, y el análisis paso-a-paso no lineal considerando los amortiguadores viscosos definitivos, fueron investigados con la idea de comparar las respuestas en función de la naturaleza del evento sísmico y el tipo de atirantamiento de los cables, considerando los mismos eventos sísmicos antes expuestos.

Los resultados de la investigación muestran que la aplicación de amortiguamiento viscoso suplementario es una eficiente estrategia para incrementar el amortiguamiento de una estructura, absorbiendo una gran cantidad de la energía de entrada, y controlando la respuesta de estructuras de período largo, sobre todo en la dirección longitudinal, en donde se manifiestan las mayores respuestas. Más de un 55% de la energía de entrada puede ser disipada usando éstos dispositivos, los cuales resultan ser igualmente efectivos para sismos de campo lejano y campo cercano, con independencia del esquema de atirantamiento empleado, por lo que constituyen una excelente estrategia de protección pasiva. Debido a la gran no linealidad de éstas estructuras, el método del espectro de respuesta debe ser considerado sólo como primera aproximación al problema, y para propósitos comparativos. Para resultados más precisos, y para aplicaciones de diseño, el análisis no lineal paso-a-paso es siempre la mejor opción. Por otro lado, ésta investigación prueba el despreciable efecto del esquema de atirantamiento en la respuesta sísmica, así como el importante aumento de la respuesta cuando son tomados en cuenta los efectos tipo pulso de la directividad de la falla, característicos de sismos de fuente cercana.
Recent seismic events have demonstrated the vulnerability of some bridges under strong ground motions. Cable-stayed bridges are an attractive bridge typology currently used for many practical purposes, constituting important structural systems to be protected against earthquakes. Amongst the current seismic protection strategies, the use of passive devices is the most robust, economic and well-suited option to improve the seismic performance of structures, in which additional energy dissipation systems is good choice. Because of their capacities, easy replacement and maintenance, as well as their interesting mechanical properties, fluid viscous dampers could be an excellent additional energy dissipation system to protect large structural systems against strong earthquakes. For that reason, the analysis, assessment and comparison of the nonlinear seismic response of concrete cable-stayed bridges, with and without the incorporation of nonlinear fluid viscous dampers in order to investigate their effectiveness for seismic protection purposes, is the main objective of this applied research.

To reach the proposed objectives, firstly, eight theoretical cable-stayed bridge models based on the well-known Walter's Bridges [Walter, 1999] were defined; considering variations of the stay cable layout, deck level, deck type and stay spacing. As a starting point of the nonlinear dynamic analysis, a nonlinear static analysis was performed for all the cases. After that, the dynamic characterization of the models was carried out by means of a modal analysis. As a first approach of the seismic response of the bridges, response spectrum analysis was performed in order to compare the seismic behaviour as function of the main variations considered, and to select the two most representative bridges to be analyzed using nonlinear time history analysis. The following stage was the seismic analysis of the selected bridge models from the previous step, applying nonlinear direct integration time history analysis, without additional energy dissipation devices, and considering both far-fault and near-fault ground motions. In these sense, five artificially generated earthquake events were considered for the far-fault analysis, as long as five real earthquake events containing long-period velocity pulses were included for the near-fault analysis, according to Chapter 3. Finally, the analysis of the optimal layout of the dampers, a parametric study to select the optimal damper parameters and the nonlinear step-by-step analysis considering the incorporation of the definitive fluid viscous dampers were investigated in order to compare the seismic responses as a function of the earthquake nature and stay cable layout, taking into account the same earthquake events before mentioned.

Results of this investigation show that application of fluid viscous dampers as additional passive energy dissipation systems is a very efficient strategy to increase the damping of a structure, absorbing a significant amount of the seismic input energy, and controlling the seismic response of long-period structures, mainly in the longitudinal direction, where the main responses occur. More than 55% of the input energy can be dissipated with these devices, being equally efficient for far-fault and near-fault ground motions, independent on the stay cable layout, which constitutes a very promising strategy to protect cable-stayed bridges against earthquakes. Because of the highly nonlinear behaviour of those structures, response spectrum analysis must be considered only as first approach to the seismic response and for comparative purposes. For more accurate analysis results, and for design applications, nonlinear time-history analysis is a necessary choice. Likewise, it is demonstrated that the effect of the stay cable layout on the nonlinear seismic response of the bridges is not very important, as well as an important increase of the seismic response when forward rupture directivity pulse effects are considered, a characteristic of near-source ground motions.
APA, Harvard, Vancouver, ISO, and other styles
22

Aguiar, Elizabeth Oshima de. "Contribuição ao estudo de estruturas de cabos para coberturas de grandes áreas livres, considerando as não linearidades física e geométrica." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-18042018-100926/.

Full text
Abstract:
A pesquisa foi desenvolvida com a finalidade de se analisar o comportamento elástico e inelástico de estruturas de cabos, sob carregamento estático, pela técnica dos elementos finitos. Para a discretização das estruturas de cabos adotou-se um elemento retilíneo isoparamétrico, e na formulação dos princípios variacionais foram considerados a não linearidade física do material e a não linearidade geométrica, inerente às estruturas de cabos. Empregou-se o método incrementai-iterativo de Newton-Raphson para a resolução do sistema de equações não lineares. Alternativamente a solução foi obtida da minimização direta da função energia potencial total da estrutura de cabos, utilizando-se o método do Gradiente Conjugado. Vários exemplos de estruturas de cabos comumente empregadas em coberturas de grandes vãos foram estudados. Os resultados obtidos segundo os dois procedimentos foram analisados e a eficiência elos métodos foi comprovada.
The research was developed with the purpose of analyzing the elaslic and the inelaslic behaviour of cable slructures, under static load. The finite element method with straight isoparametric element was used. In the formulation of the variational principles, the material and the geometric non-linearity were considered. The Newton-Raphson method was used to resolve the non-linear equations system. Alternatively the solution was obtained of the direct minimization of the total potential energy of the cable structure; in this case using the Conjugated Gradient Method. Several examples of cable structures, commonly employed in roofs of large spaces were studied. The results were obtained according to both processes and the efficiency of the methods was verified.
APA, Harvard, Vancouver, ISO, and other styles
23

Vargas, Luis Arturo Butron. "Comportamento estrutural de pontes estaiadas: efeitos de segunda ordem." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-09012008-165359/.

Full text
Abstract:
A evolução das pontes estaiadas modernas mostra a procura da engenharia de pontes por sistemas estruturais cada vez mais leves e esbeltos. No intuito de dar contexto ao problema de análise de estruturas esbeltas, de maneira geral e desde a perspectiva da concepção, se discutem os vários arranjos estruturais que podem se obter ao combinar o pilão, o sistema de suspensão por estais e o tabuleiro, elementos que compõem qualquer sistema estrutural de ponte estaiada. Este trabalho apresenta um método de análise estrutural estático não linear que considera os efeitos decorrentes da mudança da geometria da estrutura sob carregamentos (não linearidade geométrica) e os efeitos da resposta não linear da seção de concreto estrutural quando solicitada por flexão oblíqua composta (comportamento não linear do material). O programa ANLST foi elaborado para obter as relações momento-normal-curvatura e as rigidezes secantes na flexão oblíqua composta para uma seção de concreto de geometria arbitraria, esses resultados são integrados com uma análise elástica de segunda ordem, que é executada no programa SAP2000 para análise estrutural por elementos finitos. Mostra-se a formulação do método de análise elástica de segunda ordem pelo princípio dos deslocamentos virtuais, que leva em consideração os efeitos dos deslocamentos finitos dos nós do modelo para a resposta da estrutura, por meio da matriz de rigidez geométrica do elemento barra no espaço. Finalmente são apresentados dois exemplos de estruturas planas para validar o método e um exemplo de uma estrutura espacial para a aplicação do método. Todos esses exemplos mostram que os esforços e deslocamentos de segunda ordem, em este tipo de estruturas, não podem ser desprezados.
Modern cable stayed bridges evolution shows the bridge engineering searching for lightweight and slender structural systems. Trying to give context for the problem of analysis of slender structures, of a general mode and from the conception perspective, is discussed the several structural layouts that can be obtained from the combination of pylon, cable stayed suspension system and girder, elements that compose any structural system of cable stayed bridges. This work presents a method of non-linear static structural analysis that consider the resulting effects of geometry change under loading (geometric non linearity), and the effects of nonlinear response of the structural concrete section when it is loading for biaxial bending and axial force interaction (material non linearity). The ANLST program was developed to obtain the moment-axial-curvature relationships and the secant stiffness for biaxial bending and axial force interaction for a concrete section of arbitrary geometry. These results are integrated with the second order elastic static analysis, which is executed in the finite element program SAP2000 for structural analysis. A formulation of method for second order elastic analysis is shown by the virtual displacement principle, which leads in consideration the effects of finite displacement of the model\'s nodes for the structural behavior, by means of geometric stiffness matrix for space frame element. Finally are shown two examples of plane structures for the validation of the method and one example of space structure for the application of the method. All of these examples showed that second order forces and displacements can\'t be despised in this type of structures.
APA, Harvard, Vancouver, ISO, and other styles
24

Fasquelle, Benjamin. "Étude théorique et expérimentale d'architectures innovantes de robots inspirées du cou des oiseaux : conception et commande." Thesis, Ecole centrale de Nantes, 2021. https://tel.archives-ouvertes.fr/tel-03670418.

Full text
Abstract:
Les systemes biologiques representent une grande source d’inspiration pour les roboticiens. Les systemes de tensegrite, composes d’elements rigides et d’elements en tension, sont particulierement adaptes pour la bio-inspiration puisque l’on retrouve ces systemes directement dans divers systemes biologiques. Dans cette these, nous etudions un manipulateur inspire du cou des oiseaux. Ce manipulateur est un empilement de modules qui possedent chacun un degre de liberte. Chaque module est un mecanisme de tensegrite compose de quatre barres et deux ressorts. Le manipulateur est actionne a l’aide de cables, ainsi tous les moteurs se situent a sa base. Le modele geometrique et le modele dynamique du manipulateur sont developpes, puis une analyse de l’actionnement et de l’espace de travail statique du manipulateur est menee. Un actionnement avec quatre cables est selectionne pour un prototype compose de trois modules. Ce prototype n’a pas de mesure directe des orientations des modules, deux methodes pour calculer ces orientations en fonction des positions moteurs sont donc proposees. Une identification des frottements moteurs et de l’elasticite des cables est menee afin d’ameliorer les performances de la commande du prototype, et d’avoir un simulateur efficace. Trois commandes sont developpees et testees sur le prototype : une commande articulaire, une commande dans l’espace des moteurs et une commande dans l’espace operationnel. Des trajectoires sont ensuite optimisees dans le but de produire des mouvements en minimisant les forces appliquees ou de produire des mouvements a grande vitesse, comme peut le faire le pic lorsqu’il frappe un tronc d’arbre avec son bec. La these se termine sur une ouverture vers un manipulateur sousactionne constitue d’une dizaine de modules
Biological systems are a great source of inspiration for roboticists. Tensegrity systems, composed of rigidand tensile elements, are particularly suitable for bio-inspiration since these systems are found directly in various biological systems. In this thesis, we study a manipulator inspired by the neck of birds. This manipulator is a stack of modules that each have one degree of freedom. Each module is a tensegrity mechanism composed of four bars and two springs. The manipulator is operated by cables, so all the motors are located at its base. The geometric model and the dynamic model of the manipulator are developed, then an analysis of the actuation and the static workspace of the manipulator is conducted. An actuation with four cables is selected for a prototype composed of three modules This prototype has no direct measurement of the modules orientations, so two methods to calculate these orientations according to the motor positions are proposed. An identification of the motor friction and the elasticity of the cables is carried out in order to improve the performances of the prototype control, and to have an effective simulator. Three controls are developed and tested on the prototype: a joint control, a control in the space of the motors and a control in the operational area. Trajectories are then optimized in order to produce movements by minimizing the applied forces or to produce high speed movements, as the woodpecker can do when it hits a tree trunk with its beak. The thesis ends with an opening towards an underactuated manipulator made of about ten modules
APA, Harvard, Vancouver, ISO, and other styles
25

Ozerkan, Taner. "Instrumented Monitoring And Dynamic Testing Of Metu Cable Stayed Pedestrian Bridge And Comparisons Against The Analytical Model Simulations." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606335/index.pdf.

Full text
Abstract:
This study includes structural instrumentation and monitoring of a 48.5 meters long cable-stayed pedestrian bridge located on EskiSehir road near METU campus. The objectives of the study are (1) to monitor the bridge responses during erection and operation stages so that the strain changes are determined during important events such as transportation, lifting, cabling, mid-support removal, slab concrete pouring and tile placement, (2) to determine existing cable forces using vibration frequencies, and (3) comparison of the experimental and analytical results for model updating. A total of 10 vibrating wire type strain gages were used for strain readings in steel members. The readings are taken at various stages of construction at every 10 to 30 minutes intervals. The bridge responses were monitored about three months and large strain changes in the order of 300 to 500 micro-strain were recorded during important events (e.g., transportation, lifting, cabling, mid-support removal, deck cover placement). The deck and tower natural vibration frequency measurements are conducted in two main directions. Two different FE models are constructed using two levels of complexity. FEM analysis results are compared against measured natural frequencies of the bridge and tower. Simplistic analytical model is modified to include temporary support removal in order to perform staged construction simulation and investigate cable force variations. Actual cable tensile forces are obtained using measured cable natural vibration frequencies. The cable frequencies are measured using a CR10X data logger and a PCB 393C accelerometer. Existing cable forces are compared against analytical simulations and symmetrically placed cables
APA, Harvard, Vancouver, ISO, and other styles
26

Demir, Abdullah. "Form Finding And Structural Analysis Of Cables With Multiple Supports." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613609/index.pdf.

Full text
Abstract:
Cables are highly nonlinear structural members under transverse loading. This nonlinearity is mainly due to the close relationship between the final geometry under transverse loads and the resulting stresses in its equilibrium state rather than the material properties. In practice, the cables are usually used as isolated single-segment elements fixed at the ends. Various studies and solution procedures suggested by researchers are available in the literature for such isolated cables. However, not much work is available for continuous cables with multiple supports. In this study, a multi-segment continuous cable is defined as a cable fixed at the ends and supported by a number of stationary roller supports in between. Total cable length is assumed constant and the intermediate supports are assumed to be frictionless. Therefore, the critical issue is to find the distribution of the cable length among its segments in the final equilibrium state. Since the solution of single-segment cables is available the additional condition to be satisfied for multi-segment continuous cables with multiple supports is to have stress continuity at intermediate support locations where successive cable segments meet. A predictive/corrective iteration procedure is proposed for this purpose. The solution starts with an initially assumed distribution of total cable length among the segments and each segment is analyzed as an independent isolated single-segment cable. In general, the stress continuity between the cable segments will not be satisfied unless the assumed distribution of cable length is the correct distribution corresponding to final equilibrium state. In the subsequent iterations the segment lengths are readjusted to eliminate the unbalanced tensions at segment junctions. The iterations are continued until the stress continuity is satisfied at all junctions. Two alternative approaches are proposed for the segment length adjustments: Direct stiffness method and tension distribution method. Both techniques have been implemented in a software program for the analysis of multi-segment continuous cables and some sample problems are analyzed for verification. The results are satisfactory and compares well with those obtained by the commercial finite element program ANSYS.
APA, Harvard, Vancouver, ISO, and other styles
27

Georgakis, Christos Thomas. "Non-linear dynamics of cable-stays and cable-structure interaction." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369527.

Full text
APA, Harvard, Vancouver, ISO, and other styles
28

Olamigoke, Oluremi. "Structural response of cable-stayed bridges to cable loss." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/845796/.

Full text
Abstract:
Cable-stayed bridges are highly redundant structures that are vulnerable to intentional and accidental extreme events that may lead to cable loss. The potential loss of a major element, which imposes dynamic effects to the structure, can subsequently lead to the collapse of the whole structure. Codes recommend the use of dynamic amplification factors to simulate the response of cable-supported structures to the loss of a cable. Recent research has identified that this method is conservative and there is little or no guidance for carrying out detailed dynamic analysis for cable loss. The loss of one or more cables due to blast and fire using dynamic analysis method is investigated and compared to the code recommended method to account for effect of time and the event leading to cable loss hereby recommending a simplified method of dynamic analysis for cable loss. Three cable-stayed bridge models namely Model A (road traffic bridge with three semi-fan cable arrangements), Model B (road and foot traffic bridge with one single harp cable arrangement) and Model C (footbridge with two symmetrical semi-fan cable arrangement) were modelled and non-linear dynamic analysis carried out for the loss of the backstay and the longest cable using Abaqus 6.13. The effect of the cable loss due to blast and fire on the remaining cables, cable-deck connection, cross beam, longitudinal girder, deck and pylon were examined and compared to the code recommended method. The relationship between cable loss time and the natural period of the bridge was also investigated in this research. A progressive collapse check was then carried out and Dynamic Amplification Factors (DAF) were obtained for the cable loss scenarios considered for the vehicular and pedestrian cable-stayed bridges. It is therefore of importance to study whether these structures can withstand these accidental/intentional loads, fulfil their economic benefit to society and establish a guideline for carrying out the dynamic analysis not only for road traffic cable-stayed bridges but also cable-stayed footbridges.
APA, Harvard, Vancouver, ISO, and other styles
29

Botterill, Neil. "Fluid structure interaction modelling of cables used in civil engineering structures." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11657/.

Full text
Abstract:
Long, thin, flexible cylindrical elements of large scale structures are heavily influenced by the fluid flow around them. Equally, their movement has an appreciable effect on the fluid flow. This two-way interaction leads to complex dynamic behaviour that can cause fatigue and thus reduce operational lifetime. As demand for longer span bridges and drilling in deeper marine environments increases, research into the best modelling practice of this scenario gains importance. The work described in this thesis establishes a suitable method to model in CFD aero/hydro-elastic behaviour of slender cylindrical elements in large scale structures. In order to achieve this outcome, the author has: modelled the drag crisis on a static cylindrical element; developed a suitable FSI coupling program; combined the drag crisis model with the FSI coupling program and validate against published experimental data. The turbulence formulation used was carefully chosen taking into account the flow features that are important to the onset of the drag crisis. An LES formulation capable of adapting the model constant of the SGS model according to local shear conditions was identied as the best candidate to achieve this aim. The fluid and structural solvers used were loosely coupled by an explicit method that achieved a balance of kinetic energy as well as matching displacement at the moving fluid/solid interface. The integration method and implementation of this coupling strategy was verified by running a test case at low Reynolds number that produced a regular sinusoidal lift function on the cylinder that was kept stationary. The displacement, velocity, and acceleration response produced by the structural solver was compared against a closed solution and found to match with an acceptable level of error. A number of FSI simulations with the cylinder free to move in the cross-flow direction only was carried out. The displacement response was compared against published numerical and experimental data and the importance of having a sufficient spanwise dimension of flow domain was highlighted. Simulations with the cylinder free to move in the along-flow direction aswell as cross-flow direction were carried out. In some simulations where lock-in was observed, the effect of the drag crisis was clearly seen. Energy entered into the system as a result of low drag on the upstream motion of the cylinder caused by the drag crisis. More simulations at different velocities are recommended to define a displacement response curve and make further new observations.
APA, Harvard, Vancouver, ISO, and other styles
30

Wuillaume, Pierre-Yves. "Simulation numérique des opérations d’installation pour les fermes d’éoliennes offshore." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0003/document.

Full text
Abstract:
L’éolien offshore est l’énergie marine la plus avancée et utilisée dans le monde. Afin d’accroître l’énergie extraite du vent, les dimensions des éoliennes deviennent plus importantes et les parcs éoliens sont installées de plus en plus loin des côtes, où les mers sont plus agitées et les vents plus forts. De fait, les opérations marines sont plus complexes et plus chères et les fenêtres météo sont écourtées et se raréfient. Dans le cadre de cette thèse, un logiciel de simulation numérique des opérations marines est développé, en particulier pour des applications de descentes et de remontées de colis lourds. L’Algorithme aux Corps Rigides Composites, implémenté dans le logiciel InWave, est utilisé pour modéliser le système multicorps. Un modèle de câble et de treuil est développé, suivant la théorie multicorps utilisée, et comparé à la théorie câble classique dite « lumped mass ». Les efforts hydrodynamiques ainsi que les interactions hydrodynamiques sont modélisés par une théorie potentiel instationnaire satisfaisant l’hypothèse de faible perturbation, dite « weak-scatterer ». L’approche « weak-scatterer » du logiciel WS_CN est étendue aux simulations multi-flotteurs et validée par comparaison avec des données expérimentales. InWave et WS_CN sont couplés afin de résoudre l’interaction houle-structure pour des systèmes multicorps articulés en mer. Un couplage fort est adopté pour sa robustesse. L’équation de couplage est établie et validée via des comparaisons avec WS_CN. Le logiciel ainsi crée se nomme InWaveS_CN et utilise un code d’intégration en Python. Une nouvelle stratégie de maillage, basée sur un algorithme de découpe de maillages et une méthode par avance de front, est développée dans WS_CN. Enfin, des essais en bassin d’une opération de redressement ont été menés à l’ECN. La comparaison entre les simulations numériques et les données expérimentales offre une première et prometteuse validation d’InWaveS_CN
Offshore wind represents the most advanced and used marine energy in the world. To increase the wind power extraction, turbines grow in size and wind farms are installed further offshore in presence of rough seas and strong winds. Marine operations become more challenging and expensive, weather windows are shorter and less frequent. This PhD work focuses on the development of a numerical tool to simulate marine operations with consistency, in particular lowering and lifting operations. The Composite-Rigid-Body Algorithm, implemented in the numerical tool InWave, is used to model multibody systems. A cable model and a winch model are developed following this multibody approach and compared to the classical low-order lumped mass theory. Hydrodynamic loads and hydrodynamic interactions are simulated using an unsteady potential flow theory based on the weakscatterer hypothesis, implemented in the numerical tool WS_CN. This approach is extended to multibody simulations and validated with comparisons to experimental data. InWave and WS_CN are coupled to solve wavestructure interaction for articulated multibody systems with large relative motions in waves. A tight coupling is selected for its robustness. The coupling equation is derived and validated from comparisons with WS_CN. This leads to the creation of a new numerical tool, InWaveS_CN, using Python as glue code language. A new mesh strategy, based on the coupling between a panel cutting method and an advance front method, is developed in WS_CN. Experiments of an upending operation were conducted at Ecole Centrale de Nantes. The comparison between the numerical simulations and the experimental data leads to a first and promising validation of InWaveS_CN
APA, Harvard, Vancouver, ISO, and other styles
31

Dlouhý, Lukáš. "ANALÝZA NÁVRHOVÝCH PARAMETRŮ PŘEDPJATÝCH BETONOVÝCH KONSTRUKCÍ POMOCÍ OPTIMALIZAČNÍCH ALGORITMŮ." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-392296.

Full text
Abstract:
During recent years more and more emphasis has been put on saving and ecological aspects of the civil engineering industry. As the total volume of concrete being produced on our planet is immense (ca 1010 tons per year), the possibility of decreasing it by even a small percentage can bring large savings in material costs, transport and other costs and reduction of CO2 production and other pollution. Therefore, optimal analysis of design variables of concrete structures appears to be of high importance. Optimization is finding the best solution to a given problem. Many disciplines define different optimization problems and it is typically the minimum or maximum value of the objective function that is searched. It is known that mathematical procedures and algorithms to find an optimal structural design are used in practice in mechanical engineering, but the use of these tools in civil engineering is rather exceptional. Generally, scientific works deal with the optimal design of structures only. Finding of an optimal shape and dimensions is usually a question of the engineer’s experience and good “guess”, which is then verified by calculation. There are many reasons explaining why optimization in common practise is used only occasionally. One of them is the absence of proper user friendly software tools which could help within relatively short time available for structural design. Another reason is the complexity of optimization tasks as well as a lot of constraints in civil engineering design codes. Last but not least, the change of design variables of buildings, bridges and structures of special types do not express regular response. This issue is discussed in the submitted work.
APA, Harvard, Vancouver, ISO, and other styles
32

Guirardi, Daniel Mariani. "O método da relaxação dinâmica aplicado à análise de estruturas de cabos e membranas." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-29062012-151842/.

Full text
Abstract:
Nesta tese discute-se a necessidade de se desenvolver novas ferramentas para auxiliar o projeto e análise de estruturas de cabos e membranas. Esse tipo de estrutura, essencialmente não linear, é geralmente analisada por meio do Método dos Elementos Finitos, combinado com o Método de Newton-Raphson, para a resolução do sistema de equações não lineares resultante. Porém, a ausência de um campo de tensão de tração sobre toda estrutura composta por elementos finitos de cabos e membranas pode gerar uma matriz de rigidez tangente indeterminada, levando à divergência da solução pelo Método de Newton-Raphson. O Método da Relaxação Dinâmica é uma alternativa interessante para resolver problemas não lineares complicados de equilíbrio estático, na qual o problema do equilíbrio estático é resolvido por uma análise dinâmica, com integração no tempo. A resposta transiente é fictícia e não tem significado físico, entretanto a parte estacionária é a solução do problema de equilíbrio estático. Nesta tese, apresenta-se uma contextualização histórica sobre o Método da Relaxação Dinâmica, apontando as contribuições mais relevantes já desenvolvidas por outros autores. Propõe-se um procedimento de sintonia da massa dos elementos, capaz de uniformizar as condições impostas ao incremento de tempo, para se obter estabilidade do processo de integração numérica. Implementam-se as formulações dos elementos finitos adotados, bem como um algoritmo de enrugamento para os elementos de membrana e diversas rotinas de pós-processamento, no programa de elementos finitos SATS (A System for the Analysis of Taut Structures), desenvolvido pelo autor desta tese, em colaboração com seu orientador. A implementação desenvolvida é aplicada a uma série de exemplos relativos ao projeto e análise de estruturas de cabos e membranas, permitindo verificar a eficiência dos procedimentos de amortecimento e cinético e de sintonia de massa propostos.
This thesis discusses the need to develop new tools to assist the design and analysis of cables and membrane structures. This type of structures, essentially non-linear is generally analyzed using the Finite Element Method, where in most cases the solution is obtained by the Newton-Raphson Method. However, the absence of a tension stress field over the entire structure composed only with cable and membrane finite element can generate a non-positive definite tangent stiffness matrix, leading to the divergence of Newton-Raphson iterations. The Method of Dynamic Relaxation is an interesting alternative to solve complicated nonlinear problems of static equilibrium, replaced by an equivalent dynamic analysis. The transient solution is fictitious and without physical meaning, and the stationary phase provides the static equilibrium solution. This thesis presents a historical contextualization of the Dynamic Relaxation Method, highlighting the most relevant contributions already developed by other authors. A procedure for the tuning of the element masses is proposed, which is capable of making uniform the restrictions imposed to the time steps in order to preserve the stability of the numerical integration. Some adopted finite element formulations are implemented, as well as an algorithm for representing the wrinkling of membrane elements and several post-processing routines, in the SATS (A System for the Analysis of Taut Structures) finite element program, developed by the author of this thesis, in collaboration with his advisor. The developed implementation is applied to a series of examples on the design and analysis of cables and membrane structures, allowing verification of the efficiency of the procedures proposed for kinetic damping and mass tuning.
APA, Harvard, Vancouver, ISO, and other styles
33

FONSECA, JÚNIOR Armando Wilmans Nunes da. "Modelagem e análise de protótipo de ponte estaiada sob cargas dinâmicas incorporando molas de nitinol superelásticas para supressão de vibrações." Universidade Federal de Campina Grande, 2018. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1924.

Full text
Abstract:
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-09T14:06:57Z No. of bitstreams: 1 ARMANDO WILMANS NUNES DA FONSECA JÚNIOR - DISSERTAÇÃO (PPGEM) 2018.pdf: 5713433 bytes, checksum: aba957d62b27260ecd8141ce8547fa05 (MD5)
Made available in DSpace on 2018-10-09T14:06:57Z (GMT). No. of bitstreams: 1 ARMANDO WILMANS NUNES DA FONSECA JÚNIOR - DISSERTAÇÃO (PPGEM) 2018.pdf: 5713433 bytes, checksum: aba957d62b27260ecd8141ce8547fa05 (MD5) Previous issue date: 2018-08-31
Capes
No decorrer dos anos, com a construção de pontes cada vez mais longas e leves, o comportamento dinâmico passa a ser um fator limitante no projeto dessas estruturas. Portanto, é de grande interesse que sistemas de controle de vibrações estruturais sejam desenvolvidos. Entre os vários materiais utilizados atualmente para supressão de vibrações, estão as ligas com memória de forma (LMF). Estas vêm ganhando popularidade graças a sua capacidade de sofrer grandes deformações reversíveis, aliadas às suas propriedades de dissipação de energia. Neste contexto, este trabalho tem como objetivo realizar o controle passivo de vibrações num protótipo de ponte estaiada, em escala reduzida, utilizando molas superelásticas de uma LMF Ni-Ti (Nitinol). Foram realizadas análises dinâmicas na estrutura utilizando ferramentas analíticas, numéricas e experimentais. Nos resultados experimentais, obteve-se uma redução de até 75% de transmissibilidade de força em vibração livre, em comparação com a estrutura com molas equivalentes, de aço. Em vibração forçada, o valor de redução de transmissibilidade de força chegou a um máximo de 85,5%. Os resultados numéricos mostraram boa coerência na determinação dos parâmetros modais da estrutura e na resposta em vibração livre, com maior erro associado aos resultados em vibração forçada, mais especificamente no segundo modo de vibrar do sistema. Concluiu-se que as molas de LMF têm capacidade de dissipação de energia vibracional para a aplicação em estruturas de pontes e os modelos numéricos permitem uma boa previsão da resposta da estrutura.
Over the years, with the construction of increasingly longer and lighter bridges, dynamic behavior becomes a limiting factor in the design of these structures. Therefore, it is important that structural vibration control systems are developed. Among the various materials currently used for vibration suppression are the shape memory alloys (SMA). These have been gaining popularity as a result of their ability to undergo large reversible deformations, coupled with their energy dissipating properties. In this context, the objective of this dissertation is to perform the passive vibration control of a cable-stayed bridge prototype, in small scale, using SMA Ni-Ti (Nitinol) superelastic springs. Dynamic analyses were performed using analytical, numerical and experimental tools. In the experimental results, a reduction of 75% of force transmissibility in free vibration was obtained, compared to the structure with equivalent steel springs. In forced vibration, the value of reduction of force transmissibility reached a maximum of 85.5%. The numerical results showed good coherence in the determination of the modal parameters of the structure and the response of the latter in free vibration, with the largest error associated to the second mode of vibration of the structure, in forced vibration. It was concluded that the SMA springs have the capacity to dissipate vibrational energy, for the application in bridges structures, and the numerical models allow a good prediction of the structure response.
APA, Harvard, Vancouver, ISO, and other styles
34

Hlava, Martin. "Lávka pro pěší podporovaná kabely." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227217.

Full text
Abstract:
The purpose of the master’s thesis is about a concept of a pedestrian bridge´s bearing construction for pedestrian endorsed wires above a highway R35. The work includes a statical construction calculation of the suspended foot bridge of six spans, which has been chosen from three options. The chosen option is built of a monolithic, pre-stressed concrete board supported by suspenders, which is made by segmental elements above the fast highway. Calculation of a longitudinal direction has been made in an ANSYS application. Assembling status and cross direction of the construction has been modelled at SCIA Engineer. The construction´s recognition has been made manually expect of several towers cross-section, where the judgement has been made at IDEA StatiCa.
APA, Harvard, Vancouver, ISO, and other styles
35

Davalos, Elizabeth (Davalos R. ). 1975. "Structural behaviour of cable-stayed bridges." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/80924.

Full text
APA, Harvard, Vancouver, ISO, and other styles
36

Pacitti, Arnaud. "Nonlinear modeling of elastic cables : experimental data-based tension identification via static inverse problem." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1142/document.

Full text
Abstract:
La connaissance de la tension dans les câbles de pont est un élément de diagnostic important, tant à l'échelle du câble qu'à celle de l'ouvrage dont il fait partie.Le présent travail de thèse propose une méthode d'évaluation de la tension parméthode inverse à partir d'une formulation variationnelle mixte de câble géométriquement exact permettant de coupler simplement et à bas coût un modèle universel de câble et des capteurs d'utilisation courante tels que des jauges de déformation et des capteurs de déplacement. Contrairement à de nombreuses méthodes existantes, la méthode pésentée ne nécessite pas une connaissance fine des paramètres du câble pour évaluer sa tension.Les choix de modélisation faits sont motivés par une étude approfondie des différentes typologies des câbles présents sur ouvrage et par une étude bibliographique qui tente de synthétiser l'immense littérature disponible dans le domaine des câbles. La modélisation retenue est issue de la théorie des lignes déformables des frères Cosserat, dont nous présentons les variantes avec et sans rigidité de flexion.Les moyens d'essai utilisés pour la validation expérimentale de la méthode mise au point ont été conçus et réalisés au cours du présent travail. Le montage expérimental imaginé permet d'appliquer la méthode inverse sur un câble montoron multicouches de 21 m de long et 22 mm de diamètre. Les essais sont réalisés à 6 différents niveaux de tension échelonnés par paliers de 30 kN de 55 kN à 205 kN. Ils montrent l'efficacité de la méthode sur le câble testé et la pertinence de son déploiement à venir sur d'autres typologies de câbles
Knowledge of the tension in bridge cables is important not only to diagnostic the cable itself but also the construction it belongs to.The work presented in this thesis proposes to evaluate the tension of a geometrically exact cable using a static inverse method from a mixed variational formulation, by coupling simply and cheaply a universal cable model with usual sensors, such as displacement sensors and strain gauges. Contrarily to existing methods, a good knowledge of the cable's parameters, such as it length or weight per unit length, is not required.Combining a thorough study of various cable typologies encountered on bridges and the vast amounts of material available in the bibliography covering cables, lead to the modeling following the elastic theory of rods developed by the Cosserat brothers, François and Eugène, elaborating on their theory of rods with and without flexural stiffness.The experimental apparatus, designed and built in the course of this study, allowed to successfully validate the developed inverse method on a multilayered strand cable 21 m long and 22 mm in diameter at several tension levels. The universal aspect of the model introduced and its successful validation encourages its implementation to other cable typologies
APA, Harvard, Vancouver, ISO, and other styles
37

Haji, Agha Mohammad Zarbaf Seyed Ehsan. "Vibration-based Cable Tension Estimation in Cable-Stayed Bridges." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535636861655531.

Full text
APA, Harvard, Vancouver, ISO, and other styles
38

Sorrivi, Elisa <1976&gt. "Structural health monitoring and damage detection of tendons and stay cables for civil structures." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1987/1/Sorrivi_Elisa_Tesi.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
39

Sorrivi, Elisa <1976&gt. "Structural health monitoring and damage detection of tendons and stay cables for civil structures." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1987/.

Full text
APA, Harvard, Vancouver, ISO, and other styles
40

Kreis, Eri Sato. "ANA-PSp: um sistema computacional para análise aeroelástica de pontes suspensas por modelos matemáticos reduzidos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-31032008-151227/.

Full text
Abstract:
As características arquitetônicas e o desempenho estrutural de pontes suspensas, estaiadas ou pênseis, têm determinado a sua crescente utilização em obras de arte destinadas a vencer grandes vãos. Essa utilização crescente que ocorreu no mundo nas últimas décadas se repete agora nos últimos anos no país. Várias dessas obras estão em execução e em projeto. Um dos aspectos relevantes na análise estrutural das pontes suspensas é o de seu comportamento quando submetidas à ação do vento. Apresenta-se o sistema computacional ANA-PSp desenvolvido especialmente para o estudo do movimento de tabuleiros de pontes suspensas sujeitas a esforços aeroelásticos e aerodinâmicos. Esse sistema computacional formado por um conjunto de subsistemas, é elaborado para a análise aeroelástica de pontes suspensas sob a ação de vento e permite análises paramétricas extensas dos fenômenos de drapejamento (flutter) e de martelamento (buffeting). A discretização da estrutura é efetuada pelo método dos elementos finitos e a redução dos graus de liberdade é realizada por superposição modal com modos selecionados que melhor descrevem os movimentos do tabuleiro. Utiliza-se modelo matemático reduzido para a análise multimodal no domínio do tempo e da freqüência. A velocidade crítica ou velocidade de drapejamento é determinada por procedimento de autovalores complexos com a obtenção de freqüências e taxas de amortecimentos modais para várias velocidades do vento. Adicionalmente, o fenômeno do drapejamento é estudado por séries temporais de respostas de coordenadas generalizadas e de deslocamentos selecionados e por análise espectral dessas séries temporais, que permitem a verificação das características de vibração do tabuleiro da ponte no domínio da freqüência. O estudo do fenômeno de martelamento considera esforços aeroelásticos determinísticos e esforços aerodinâmicos estocásticos e apresentam-se resultados em espectros de potência de deslocamentos e em desvios padrão de deslocamentos ao longo do tabuleiro. Para validar o sistema ANA-PSp, apresentam-se estudos de caso para a ponte estaiada da Normandia, para a ponte pênsil colapsada de Tacoma Narrows e para a ponte estaiada projetada, mas não executada, sobre o Rio Tietê e localizada na extremidade do complexo viário Jacu-Pêssego.
The architectonic characteristics and the structural performance of suspension bridges and cable-stayed bridges have determined their growing use on large span bridges. This growing usage, which has occurred world-wide during the last decades, is now being repeated in Brazil during the last few years. Several such bridges are presently either undergoing construction or being designed. One of the outstanding aspects in the structural analysis of suspension bridges is their behavior under wind action. This paper presents the computer system ANA-PSp, specially developed for studying the movement of suspended bridge decks under aeroelastic and aerodynamic forces. This computer system is formed by a group of subsystems and is created for aeroelastic analysis of suspended bridges under wind action. It allows extended parametric analyses of the flutter and the buffeting phenomena. Structural discretization is done by the finite element method and the reduction of degrees of freedom is obtained by modal superposition of the selected modes which best describe the deck movements. A reduced mathematical model is used for the multimodal analysis in the time and frequency domains. Critical velocity or flutter velocity is determined by a procedure of complex eigenvalues which obtains frequencies and damping ratios for different wind speeds. Additionally, the flutter phenomenon is studied by temporal series of answers to generalized coordinate responses and of selected displacements by spectral analysis of such temporal series, which allow us to verify the characteristics of the vibrations of the bridge deck in the frequency domain. The study of the buffeting phenomenon considers deterministic aeroelastic and stochastic aerodynamic forces. The paper presents results in displacement power spectra and in the standard deviation of displacements along the deck. In order to validate system ANA-PSp, case studies are presented for the cable-stayed Ponte de Normandie in Le Havre (France), for the collapsed suspension bridge on Tacoma Narrows and for the cable-stayed bridge, already designed but not built, on Tietê River, located at one end of the highway complex Jacu-Pêssego (São Paulo, SP, Brazil).
APA, Harvard, Vancouver, ISO, and other styles
41

De, Souza Barry-Jon. "The dynamical effects of dendritic structure on neural systems." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/28072.

Full text
Abstract:
The role of the dendritic tree and the way it functions within a neuron has been of interest to neurologists for over a century. As investigative techniques have become more sophisticated and thus revealing, our perception of the dendrites as being purely an information gathering component has changed to one where the dendritic tree may be viewed as a highly complex, nonlinear information processor. In spite of this most mathematical studies of the dynamical behaviour of neural populations have neglected the influence of the dendritic tree. The aim of this thesis is to address this imbalance.
APA, Harvard, Vancouver, ISO, and other styles
42

Lorenzo, Rodolfo. "Modelling of cable-structure interaction in cable-stayed bridges and examination of their autoparametric response under stochastic loading." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424047.

Full text
APA, Harvard, Vancouver, ISO, and other styles
43

Spraul, Charles. "Suivi en service de la durée de vie des ombilicaux dynamiques pour l’éolien flottant." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0007/document.

Full text
Abstract:
Le travail présenté vise à mettre en place une méthodologie pour le suivi en service de la fatigue mécanique pour l’ombilical dynamique d’un système EMR flottant. L’approche envisagée consiste à simuler à l’aide d’outils numériques la réponse de l’ombilical aux cas de chargement observés sur site. Le post-traitement des résultats de ces simulations devant permettre d’accéder à différentes quantités d’intérêt en tout point du câble. Pour quantifier et réduire l’incertitude sur la réponse calculée de l’ombilical ce dernier doit être instrumenté. Un certain nombre de paramètres du modèle numérique feront alors l’objet d’une calibration régulière pour suivre l’évolution des caractéristiques de l’ombilical susceptibles d’évoluer. Dans ce contexte ce manuscrit présente et compare différentes méthodes pour analyser la sensibilité de la réponse de l’ombilical aux paramètres susceptibles d’être suivis. L’objectif est notamment d’orienter le choix des mesures à mettre en oeuvre. L’analyse en composantes principales permet pour cela d’identifier les principaux modes de variation de la réponse de l’ombilical en réponse aux variations des paramètres étudiés. Différentes approches sont également envisagées pour la calibration des paramètres suivis,avec en particulier le souci de quantifier l’incertitude restante sur le dommage. Les méthodes envisagées sont coûteuses en nombre d’évaluations du modèle numérique et ce dernier est relativement long à évaluer. L’emploi de méta-modèles en substitution des simulations numériques apparait donc nécessaire, et là encore différentes options sont considérées. La méthodologie proposée est appliquée à une configuration simplifiée d’ombilical dans des conditions inspirées du projet FLOATGEN
The present work introduces a methodology to monitor fatigue damage of the dynamic power cable of a floating wind turbine. The suggested approach consists in using numerical simulations to compute the power cable response at the sea states observed on site. The quantities of interest are then obtained in any location along the cable length through the post-treatment of the simulations results. The cable has to be instrumented to quantify and to reduce the uncertainties on the calculated response of the power cable. Indeed some parameters of the numerical model should be calibrated on a regular basis in order to monitor the evolution of the cable properties that might change over time. In this context, this manuscript describes and compares various approaches to analyze the sensitivity of the power cable response to the variations of the parameters to be monitored. The purpose is to provide guidance in the choice of the instrumentation for the cable. Principal components analysis allows identifying the main modes of power cable response variations when the studied parameters are varied. Various methods are also assessed for the calibration of the monitored cable parameters. Special care is given to the quantification of the remaining uncertainty on the fatigue damage. The considered approaches are expensive to apply as they require a large number of model evaluations and as the numerical simulations durations are quite long. Surrogate models are thus employed to replace the numerical model and again different options are considered. The proposed methodology is applied to a simplified configuration which is inspired by the FLOATGEN project
APA, Harvard, Vancouver, ISO, and other styles
44

Choi, Jiduck. "Investigation of the dynamic behavior of a cable-harnessed structure." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/49114.

Full text
Abstract:
To obtain predictive modeling of a spacecraft, the author investigates the effects of adding cables to a simple structure with the goal of developing an understanding of how cables interacting with a structure. In this research, the author presents predictive and accurate modeling of a cable-harnessed structure by means of the Spectral Element Method (SEM). A double beam model is used to emulate a cable-harnessed structure. SEM modeling can define the location and the number of connections between the two beams in a convenient fashion. The proposed modeling is applied and compared with the conventional FEM. The modeling approach was compared to and validated by measurement data. The validated modeling was implemented to investigate the effect of the number of connections, of the spring stiffness of interconnections, and of mass portion of an attached cable. Damping has an important role in structural design because it reduces the dynamic response, thereby avoiding excessive deflection or stress, fatigue loads, and settling times. Experimental results with some specimens indicate a clear change of damping on the main structure with the inclusion of cable dynamics. The author investigated the modification of the damping of the host structure induced by various attached cables. The identification of a damping matrix is performed using measured data. The effect of the flexibility of a cable harness on damping is observed through experiments with various types of cables. The effect of the number of connections on damping is also investigated by changing the number of connections. Moreover, to overcome the sensitivity to noise in measured data of damping matrix identification approach, various methods are compared with a simulated lumped model and real test results. An improved damping matrix identification approach is proposed and can generate the unique damping matrix over the full frequency range of interest.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
45

Larocca, Ana Paula Camargo. "O uso do GPS como instrumento de controle de deslocamentos dinâmicos de obras civis - aplicação na área de transportes." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-29052006-170441/.

Full text
Abstract:
Este trabalho apresenta o desenvolvimento de metodologia para avaliar a utilização do Sistema de Posicionamento Global (GPS) como ferramenta de pesquisa no estudo do comportamento dinâmico de obras viárias. Para ser caracterizado como um instrumento de medição, foi estudada a potencialidade de um método, que se fundamenta numa forma específica de coleta e processamento de dados GPS; análise dos resíduos resultantes do processamento da dupla diferença de fase e aplicação de análise espectral para filtragem de informações indesejáveis (multicaminhamento dos sinais GPS). A coleta envolve um oscilador eletro-mecânico, especialmente projetado, que permite calibrar as medidas de amplitude e freqüência das oscilações mensuráveis pela obra sob teste. Inúmeros experimentos foram realizados em ambientes de reflexões e difrações variáveis e com diversos tipos de receptores e antenas GPS. Alguns ensaios foram realizados utilizando, simultaneamente, equipamentos como transdutores de deslocamento, acelerômetros e estações totais. Comparando os resultados obtidos, mesmo com valores prescritos em normas e códigos, afirma-se que o GPS, sob o método de coleta de dados testado, é um instrumento confiável para detecção e caracterização do comportamento dinâmico de estruturas, apresentado confiabilidade para as medições realizadas, da ordem de décimos de milímetro. Quanto à detecção das freqüências, as mais baixas ficam comprometidas pela presença do multicaminhamento e as mais elevadas têm a detecção limitada pela máxima taxa de coleta dos receptores (Lei de Nyquist)
This work presents the development of a methodology to appraise the use of Global Positioning System (GPS) as a tool for researching of dynamic behavior of road transport structures. To be characterized as an instrument for measuring it was studied the potentiality of one method which includes a specific mode of GPS data collection; analyses of double difference phase residuals and application of spectral analyses and filtering for excluding undesirable information (multipath). The GPS data collected applies an electro-mechanical oscillator, specially built for that, which permits to calibrate the measures of frequency and amplitude of structure’s oscillations under dynamic load test. Several field tests were carried out in vicinities with high and low capacity of causing signal reflections and diffractions and with different types of GPS receivers and GPS antennas. A couple of fields were carried out using, at the same time, transducers of displacement, accelerometers and total stations. Comparing these results obtained even with values of codes, it is affirmed that GPS, under the data collection method tested, it is a trustworthy instrument for detection and characterization of dynamic behavior of structures, presenting reliability of measures ranging around tenths of millimeters. The very low frequencies are highly degraded by multipath and very high frequencies have its detection limited by the receiver data rate (Theorem’s Nyquist)
APA, Harvard, Vancouver, ISO, and other styles
46

DELL'AMORE, FACH STEFANO. "Un accurato modello analitico per la statica dei ponti strallati di grande luce." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/478.

Full text
Abstract:
The conflicting demands connected from a side to the crossing of span always longer and from the other to the containment of the environmental impact of the structures set the necessity to critically re-examine the designing aspects that has brought to define the actual standards for the realization of long span cable bridges. In the case of fan-shaped scheme with "H" towers, the analysis of the statical behaviour of such structures through analytical approaches in closed form is currently founded on continuous models where the interaction between the girder and the cables is modeled through the Dischinger's tangent theory, that is through a first order approach in the displacements. In the case of non too long span, such approach allows to model in a satisfactory way the intrinsic non linear behaviour of such structures, connected to the presence of complexes structural elements as cables. On the other hand, when the spans become meaningful, the effects of interaction cable-girder can strongly be influenced by the high geometric non linearity in the behaviour of the cables "almost perpendicular" with respect to the weight force's direction, that is with respect to the forces's direction which act on the deck and therefore on the cables themselves. In this case, the sag effect with respect to the configuration of cable's chord is strong and, also holding valid the hypothesis of small displacements for the girder, the correct modeling of the behaviour of the whole structure has to bring in account the strong non linearity of the mechanical response of such structural elements. Starting from a "quasi-secant" model to describe the behaviour of the single cable, giving a second order approximation both with respect to the stress variation and to the apparent chord-strain one, the cable-girder interaction is modeled through a second order displacement approach able to take into account the finite variation of the cable's chord direction induced by the deformation of the stay-supported deck. In this way a closed-form formulation is obtained which, unlike classical secant model, does not need iterative procedures. Considering then a Eulero-Bernoulli model to describe the bending behaviour of the girder and a De Saint Venant model to decribe the torsional one, a refined continous model of the whole structure able to describe its statical behaviour has been developed. Moreover closed form solutions of the model, developed according to perturbative tecnique and valid under generic load acting on the bridge's deck, are proposed. The proposed results obtained from the present model and the comparisons effected confirm the best correspondence of the proposed approach in relationship to the behaviour attended of the structure, putting in evidence a prevailing truss behaviour of the bridge and the coupled nature of the bending and torsion of the girder, induced by the strong non linearity of the actions of cable-girder interaction.
APA, Harvard, Vancouver, ISO, and other styles
47

Calvário, Miguel Pita Soares da Fonseca. "Modelling a cable structure for a new wind energy production device." Master's thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/5118.

Full text
Abstract:
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Mecânica Especialização em Concepção e Produção
The following thesis subject is based on the identification and dimensioning of the main mechanical components of the ground station of Boreas prototype, as well as a three-dimensional finite element analysis of structural cable that connects the ground station to the module's air system. The module powered by a lift force pulls a cable that drives a mechanical system which in turn drives a generator during the productive phase of the energy cycle. In the other phase, the system inverts the turn and energy is consumed. The production of energy should be greater than the energy consume. The dimensioning of main mechanical components of ground station includes: flywheel, cable, capstan drum and winder drum. Structural analysis of the cable is performed with an algorithm based on a three-dimensional finite element analysis, which allows the control of cable tension on the end of capstan, prevent the rupture of cable, avoid high forces on bearings and the shock between the rope and the ground. The results of programme developed with the algorithm, are compared with the results obtained by an analytical approach and with commercial software of finite elements. This thesis contributes to the realization of mechanical components included in the prototype.
APA, Harvard, Vancouver, ISO, and other styles
48

Judge, Ryan. "Structural cables subjected to blast fragmentation." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/12073/.

Full text
Abstract:
In civil engineering, steel cables are widely used in the construction of bridges and sports stadia. However, their robustness and resilience against explosively formed fragment impact, whether accidental or malicious, remains largely unknown and very little research has been carried out on this subject to date. The concern is that small fragments projected from the explosion and travelling at high velocity may induce significant damage to the cables. This damage could rupture a cable releasing large amounts of kinetic energy into the surrounding structure and other damaged cables resulting in multiple cable loss and possible disproportionate collapse of the structure. To begin investigating this problem a good understanding of the localised damage sustained by the cables on impact is required. The work described within this thesis begins to address this problem by use of both physical tests and detailed finite element analysis. The tests involved firing fragment simulating projectiles at velocities ranging from 200 – 1400 m/s at un-tensioned spiral strand cables. Detailed finite element models have been developed for the spiral strand cables, with careful considerations given to the geometry of the cables, inter-wire contact mechanics, cable end boundary conditions and material modelling. The numerical results have been verified by comparison with the test results, with particular attention paid to the localised damage area, the fragment penetration depth, and the number of heavily damaged and totally broken wires. A global response study has also been undertaken on a case study structure to assess the effects of sudden cable loss. The work contained with this thesis forms part of larger research programme studying the robustness and resilience of cable supported structures subjected to highly transient loading conditions.
APA, Harvard, Vancouver, ISO, and other styles
49

Rajapakshage, Ruwanika Chandramani Piyasena. "Blast response of cable supported glass facades." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/135994/1/Ruwanika%20Chandramani%20Piyasena_Rajapakshage_Thesis.pdf.

Full text
Abstract:
This research developed techniques to determine the response of cable supported glass facades to credible blast events and evaluated the effects of controlling parameters. Research outcomes will enable to provide mitigation strategies to vulnerable buildings fronted by such glass facades.
APA, Harvard, Vancouver, ISO, and other styles
50

Zhang, Jing, and 张静. "Modelling strategies for structural health monitoring of cable-stayed bridges." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197103.

Full text
Abstract:
Long-span cable-stayed bridges have gained increasing popularity due to their appealing aesthetics, increased stiffness compared to the suspension bridges, and relatively small size of bridge components. For cable-stayed bridges with steel girders in particular, fatigue has been one of the most important failure modes and the prediction of the remaining fatigue lives has been the primary focus in recent years. To enable the evaluation of fatigue performance, a reasonable baseline finite element model reflecting the real structural behaviour is indispensable. This thesis describes the establishment of baseline finite element models of cable-stayed bridges for fatigue analysis considering the mean stress effect. Ting Kau Bridge in Hong Kong is chosen as a real life example to demonstrate the practical application of the methods developed. Firstly, the initial cable forces of the finite element model of the cable-stayed bridge are calibrated to ensure that the initial geometry of the finite element model under permanent loading agrees with that specified on the as-built drawings within reasonable tolerance. The traditional cable force adjustment method is often a trial-and-error process which is empirical, time-consuming and occasionally difficult in convergence. An optimization method based on the Kriging surrogate model is therefore developed in order to establish the relation between the deck geometry and he initial cable forces of the cable-stayed bridge. The efficiency of the proposed approach is further verified using Ting Kau Bridge against the traditional method. Furthermore, the initial finite element model developed on the basis of engineering blueprints is updated by modifying the uncertain parameters so as to achieve a refined model using the Kriging predictor. An objective function can be formulated in terms of the discrepancy between the theoretical and measured responses captured by the Wind and Structural Health Monitoring System (WASHMS) installed on the bridge. A novel feature of the proposed method is that it enables the simultaneous use of static load testing data and the dynamic information, which is not feasible by using the conventional sensitivity-based approaches. Finally, the fatigue lives of selected critical components of Ting Kau Bridge are worked out with different methods including the deterministic and probabilistic approaches based on the baseline finite element model. In the deterministic approach, the equivalent annual standard fatigue vehicle spectrum is built based on the WASHMS measurements to estimate the damage accumulation and predict fatigue lives. In the probabilistic approach, a probabilistic loading model is proposed to simulate the vehicles running along the bridge by using the available information collected by the weigh-in-motion system. Combined with the traffic load model, a statistical approach is employed to obtain the stress time-histories, and the probability density curve of the fatigue life can be obtained. One significant advantage of the proposed method is that the diurnal variation of traffic flow within different time intervals can be accounted for properly. The results of these approaches are compared with one another. As the mean stress effect is significant in the estimation of fatigue lives, the baseline calibration of cable-stayed bridges is considered essential.
published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the bibliographies on the topic 'Cable structures' for other source types:
Journal articles Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography