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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Large-Scale Cyclic Testing and Development of Ring Shaped - Steel Plate Shear Walls for Improved Seismic Performance of Buildings

Phillips, Adam Richard 28 November 2016 (has links)
A novel shear wall system for building structures has been developed that improves upon the performance of conventional steel plate shear walls by mitigating buckling. The new structural system, called the Ring Shaped - Steel Plate Shear Wall, was investigated and developed through experimental and computational methods. First, the plastic mechanism of the system was numerically derived and then analytically validated with finite element analyses. Next, five large-scale, quasi-static, cyclic experimental tests were conducted in the Thomas M. Murray Structures Laboratory at Virginia Tech. The large-scale experiments validated the system performance and provided data on the boundary frame forces, infill panel shear deformation modes, buckling mode shapes, and buckling magnitudes. Multiple computational modeling techniques were employed to reproduce different facets of the system behavior. First, detailed finite element models were constructed to accurately reproduce the cyclic performance, yielding pattern, and buckling mode shapes. The refined finite element models were utilized to further study the boundary element forces and ultra-low cycle fatigue behavior of the system. Second, reduced-order computational models were constructed that can accurately reproduce the hysteretic performance of the web plates. The reduced-order models were then utilized to study the nonlinear response history behavior of four prototype building structures using Ring Shaped - Steel Plate Shear Walls and conventional steel plate shear walls. The nonlinear response history analyses investigated the application of the system to a short period and a long period building configuration. In total 176 nonlinear response history analyses were conducted and statistically analyzed. Lastly, a practical design methodology for the Ring Shaped - Steel Plate Shear Wall web plates was presented. The experimental tests and computational simulations reported in this dissertation demonstrate that Ring Shaped - Steel Plate Shear Walls are capable of improving seismic performance of buildings by drastically reducing buckling and improving cyclic energy dissipation. / Ph. D.
2

Méthodes et outils pour des expériences difficiles sur Grid 5000 : un cas d'utilisation sur une simulation hybride en électromagnétisme / Methods and tools for challenging experiments on Grid’5000 : a use case on electromagnetic hybrid simulation

Ruiz, Cristian 15 December 2014 (has links)
Dans le domaine des systèmes distribués et du calcul haute performance, la validation expérimentale est de plus en plus utilisée par rapport aux approches analytiques. En effet, celles-ci sont de moins en moins réalisables à cause de la complexité grandissante de ces systèmes à la fois au niveau logiciel et matériel. Les chercheurs doivent donc faire face à de nombreux challenges lors de la réalisation de leurs expériences rendant le processus coûteux en ressource et en temps. Bien que de larges plateformes parallèles et technologies de virtualisation existent, les expérimentations sont, pour la plupart du temps, limitées en taille. La difficulté de passer une expérimentation à l'échelle représente un des grands facteurs limitant. Le niveau technique nécessaire pour mettre en place un environnement expérimentale approprié ne cesse d'augmenter pour suivre les évolutions des outils logiciels et matériels de plus en plus complexes. Par conséquent, les chercheurs sont tentés d'utiliser des méthodes ad-hoc pour présenter des résultats plus rapidement et pouvoir publier. Il devient alors difficile d'obtenir des informations sur ces expérimentations et encore plus de les reproduire.Une palette d'outils ont été proposés pour traiter cette complexité lors des expérimentations. Ces outils sont motivés par le besoin de fournir et d'encourager des méthodes expérimentales plus construites. Cependant, ces outils se concentrent principalement sur des scénarios très simple n'utilisant par exemple qu'un seul noeud ou client/serveur. Dans le contexte des systèmes distribués et du calcul haute performance, l'objectif de cette thèse est de faciliter la création d'expériences, de leur contrôle, répétition et archivage.Dans cette thèse nous proposons deux outils pour mener des expérimentations nécessitant une pile logicielle complexe ainsi qu'un grand nombre de ressources matérielles. Le premier outil est Expo. Il permet de contrôler efficacement la partie dynamique d'une expérimentation, c'est à dire l'enchaînement des tests expérimentaux, la surveillance des taches et la collecte des résultats. Expo dispose d'un langage de description qui permet de mettre en place une expérience dans un contexte distribué avec nettement moins de difficultés. Contrairement aux autres approches, des tests de passage à l'échelle et scénarios d'usage sont présentés afin de démontrer les avantages de notre approche. Le second outil est appelé Kameleon. Il traite les aspects statiques d'une expérience, c'est à dire la pile logicielle et sa configuration. Kameleon est un logiciel qui permet de décrire et contrôler toutes les étapes de construction d'un environnement logiciel destiné aux expérimentations. La principale contribution de Kamelon est de faciliter la construction d'environnements logiciels complexes ainsi que de garantir de futur reconstructions. / In the field of Distributed Systems and High Performance Computing experimental validation is heavily used against an analytic approach which is not feasible any more due to the complexity of those systems in terms of software and hardware.Therefore, researchers have to face many challenges when conducting their experiments, making the process costly and time consuming. Although world scale platforms exist and virtualization technologies enable to multiplex hardware, experiments are most of the time limited in size given the difficulty to perform them at large scale.The level of technical skills required for setting up an appropriate experimental environment is risen with the always increasing complexity of software stacks and hardware nowadays. This in turn provokes that researchers in the pressure to publish and present their results use ad hoc methodologies.Hence, experiments are difficult to track and preserve, preventing future reproduction. A variety of tools have been proposed to address this complexity at experimenting. They were motivated by the need to provide and encourage a sounder experimental process, however, those tools primary addressed much simpler scenarios such as single machine or client/server. In the context of Distributed Systems and High Performance Computing, the objective of this thesis is to make complex experiments, easier to perform, to control, to repeat and to archive. In this thesis we propose two tools for conducting experiments that demand a complex software stack and large scale. The first tool is Expo that enable to efficiently control the dynamic part of an experiment which means all the experiment workflow, monitoring of tasks, and collection of results.Expo features a description language that makes the set up of an experiment withdistributed systems less painful. Comparison against other approaches, scalability tests anduse cases are shown in this thesis which demonstrate the advantage of our approach.The second tool is called Kamelon which addresses the static part of an experiment,meaning the software stack and its configuration.Kameleon is a software appliance builderthat enables to describe and control all the process ofconstruction of a software stack for experimentation.The main contribution of Kameleon is to make easy the setup of complex software stacks andguarantee its post reconstruction.

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