Ações sísmicas ocorrem com pouca freqüência e intensidade no Brasil, porém ocorrem em países da América Latina situados na costa do Pacífico e em Portugal, despertando o interesse da engenharia brasileira nesse assunto. Neste trabalho, apresenta-se um modelo numérico para análise de estruturas metálicas aporticadas planas com comportamento elasto-plástico sob excitação aleatória induzida por sismos. Para simular as vibrações aleatórias, utiliza-se uma simulação tipo Monte Carlo fundamentada no ?Vento Sintético?, proposta pelo Prof. Mário Franco. Nessa simulação, combinações de séries de carregamentos harmônicos são geradas com suas amplitudes extraídas de uma Função de Densidade Espectral de Potência (PSDF) das acelerações do solo e com ângulos de fase obtidos por um algoritmo pseudo-aleatório. A PSDF utilizada é um modelo reduzido do modelo Kanai-Tajimi que determina combinações de séries adimensionais, onde seus resultados para o trecho elástico são calibrados com o espectro de resposta elástica sugerido em norma internacional. A integração numérica passo-a-passo no domínio do tempo é feita para cada função de carregamento adotando-se o método de Newmark. O efeito elastoplástico é modelado pelo conceito de rótulas plásticas, assim, a cada passo é verificada a formação da rótula. Se certa seção atingir o momento fletor de plastificação, o valor do momento permanece constante e introduz-se uma rótula nessa seção com rigidez a flexão nula, permitindo rotações finitas livres. Em caso de reversão da direção do momento fletor, a rigidez elástica é integralmente recuperada com a eliminação da rótula do modelo. Ao final desse processo, obtém-se uma grande quantidade de dados de resposta. Faz-se um tratamento estatístico desses resultados de modo a concluir, do ponto de vista da engenharia, a probabilidade de ocorrência dos eventos. Para validar a metodologia proposta, analisou-se um edifício com cinco pavimentos. Os resultados satisfatórios foram obtidos quando comparados com exemplos da literatura, além de apresentarem-se estável com relação a integração no tempo. / Seismic actions occur with low intensity and often in Brazil, however they occur in Latin-American countries on the Pacific Coast and in Portugal, arousing interest in this subject of the Brazilian engineering. In this work, a numerical model is presented for the analysis on the elastic-plastic behavior of steel planar framed structures under random seismic excitation. For random vibrations, a Monte Carlo type simulation is used. This simulation is based on the ?Synthetic Wind?, proposed by Prof. Mario Franco. In this simulation, combinations of series of harmonic loads are generated with their amplitude given by certain provided Power Spectrum Density Functions (PSDF) of ground acceleration and pseudorandomly set phase angles. The used PSDF is reduced model of the Kanai-Tajimi model that determine combinations of non-dimensional series whose results by the behavior elastic are adjusted by international codes Elastic Response Spectra. The step-by-step time integration is performed for each load function using the Newmark method. In order to model, the elastoplastic effect is used the plastic hinge concept. Therefore, at each step the hinge formation is verified. If a certain section reaches its full plastic bending moment, this value of moment is maintained and a hinge in that section is introduced in the model with null stiffness, allowing for free finite rotations. If the rotation in a certain hinged section is reversed, elastic behavior is restored by elimination of the hinge from the model. At the end of this process, a large quantity of response data is obtained. A statistic treatment of these results is performed, in the way that is possible conclude, from the engineering point of view, the probability of occurrence of these events. A statistic treatment based sound engineering conclusions is done for the happened probable events. In order to validate the proposed methodology, a five stories building is analyzed. Satisfactory agreement is obtained when compared to results from the literature, and the results are very stable with respect to the time integration.

<p> A method for tlie dynamic analysis· of planar coupled shear walls subjected to ground motions is developed herein. The method is capable of application to nonuniform coupled shear walls resting on flexible foundations. The possibility-of development of yield hinges at the ends of the connecting beams is included in the analysis . Also P-& Effect is incorporated in the stiffness of the structure. </p> <p> The method is based on the transfer matrix technique in combination with the continuum method. A step-by-step integration approach is used in solving the equation of motion. The response to a number of earthquake records are obtained. The effect of the rotational ductility factor of connecting beams is studied. </p> / Thesis / Master of Engineering (MEngr)

This thesis presents an investigation of the modelling and optimal design of a particular 3-degree-of-freedom (DOF) XYθz micro-motion stage. This stage provides micron-scale motion in X and Y directions and a rotation about the Z-axis. Such a stage can be used for applications where positioning of components with micrometre, or even nanometre positioning accuracy is required. Some applications are; the positioning of samples in a scanning-electron-microscope; the positioning of masks in lithography; aligning fibre-optics and lasers; and manipulation of micro-scale objects in micro-biology or micro-systems assembly. The XYθz micro-motion stage investigated in this study uses a particular topology of monolithic compliant mechanism and three stack piezoelectric actuators. The compliant mechanism used is a 3RRR (three revolute-revolute-revolute) parallel compliant mechanism using flexure hinges. This parallel mechanism uses three RRR linkages. Each of the three RRR linkages uses three circular profile flexure hinges. Each flexure hinge provides predominantly rotational motion about one axis. This topology of mechanism has a symmetrical structure and provides numerous advantages that make it appropriate for use in a micro-motion stage. However, as yet this topology of compliant mechanism has only been investigated by a handful of researchers and it has not been used in any commercially developed systems. The design methodology of a stage using the 3RRR compliant mechanism has not been investigated in detail. In this thesis a study is presented that investigates different approaches to model the 3RRR compliant mechanism and also considers the piezo-actuator modelling, to give the complete XYθz micro-motion stage. Three models are presented and compared; the Pseudo-Rigid-Body Model (PRBM); a two-dimensional Finite-Element-Model (2-D FEM); and a third model is developed that is similar to the PRBM, but uses analytical equations to model the multiple degree-of-freedom compliance of the flexure hinges. The models developed are then used in parametric study so that the relationship between design parameters and output behaviour can be understood. An optimal design approach is then presented to develop an XYθz micro-motion stage for a particular application in a Scanning-Electron-Microscope (SEM). Finally experimental validation of the models is presented. The results of this study indicate which modelling approaches are accurate enough to prove useful for design, while also considering which models are computationally simple enough to be efficient and easy to use. The kinematic and dynamic behaviour of the 3RRR compliant mechanism and XYθz micro-motion stage is discussed in detail. This includes; a comprehensive description of the stage workspace, defining reachable and constant-rotation workspace areas; a discussion of actuator coupling; and in depth investigation of the modes of vibration. The results of the parametric study provide useful insight to aid the design of the XYz micro-motion stage and help simplify optimal design. The parametric study also highlights the difference in trends predicted by different modelling methods, which demonstrates the importance of using an appropriate model in design. The experimental validation demonstrates the accuracy of some modelling approaches while highlighting the limited accuracy of others. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1272186 / Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2007

This thesis presents an investigation of the modelling and optimal design of a particular 3-degree-of-freedom (DOF) XYθz micro-motion stage. This stage provides micron-scale motion in X and Y directions and a rotation about the Z-axis. Such a stage can be used for applications where positioning of components with micrometre, or even nanometre positioning accuracy is required. Some applications are; the positioning of samples in a scanning-electron-microscope; the positioning of masks in lithography; aligning fibre-optics and lasers; and manipulation of micro-scale objects in micro-biology or micro-systems assembly. The XYθz micro-motion stage investigated in this study uses a particular topology of monolithic compliant mechanism and three stack piezoelectric actuators. The compliant mechanism used is a 3RRR (three revolute-revolute-revolute) parallel compliant mechanism using flexure hinges. This parallel mechanism uses three RRR linkages. Each of the three RRR linkages uses three circular profile flexure hinges. Each flexure hinge provides predominantly rotational motion about one axis. This topology of mechanism has a symmetrical structure and provides numerous advantages that make it appropriate for use in a micro-motion stage. However, as yet this topology of compliant mechanism has only been investigated by a handful of researchers and it has not been used in any commercially developed systems. The design methodology of a stage using the 3RRR compliant mechanism has not been investigated in detail. In this thesis a study is presented that investigates different approaches to model the 3RRR compliant mechanism and also considers the piezo-actuator modelling, to give the complete XYθz micro-motion stage. Three models are presented and compared; the Pseudo-Rigid-Body Model (PRBM); a two-dimensional Finite-Element-Model (2-D FEM); and a third model is developed that is similar to the PRBM, but uses analytical equations to model the multiple degree-of-freedom compliance of the flexure hinges. The models developed are then used in parametric study so that the relationship between design parameters and output behaviour can be understood. An optimal design approach is then presented to develop an XYθz micro-motion stage for a particular application in a Scanning-Electron-Microscope (SEM). Finally experimental validation of the models is presented. The results of this study indicate which modelling approaches are accurate enough to prove useful for design, while also considering which models are computationally simple enough to be efficient and easy to use. The kinematic and dynamic behaviour of the 3RRR compliant mechanism and XYθz micro-motion stage is discussed in detail. This includes; a comprehensive description of the stage workspace, defining reachable and constant-rotation workspace areas; a discussion of actuator coupling; and in depth investigation of the modes of vibration. The results of the parametric study provide useful insight to aid the design of the XYz micro-motion stage and help simplify optimal design. The parametric study also highlights the difference in trends predicted by different modelling methods, which demonstrates the importance of using an appropriate model in design. The experimental validation demonstrates the accuracy of some modelling approaches while highlighting the limited accuracy of others. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1272186 / Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2007

Cette thèse s'articule autour de la détection de similarités globales et locales dans les structures protéiques. Premièrement les structures sont comparées, mesurées en termes de distance métrique dans un but de classification supervisée. Cette classification des domaines structuraux au sein de classifications hiérarchiques se fait par le biais de dominances et d'apprentissages permettant d'assigner plus rapidement et de manière exacte de nouveaux domaines. Deuxièmement, nous proposons une méthode de manière de traduire un problème biologique dans les formalisme des graphes. Puis nous résolvons ce problème via le parcours de ces graphes pour extraire les différentes sous-structures similaires. Cette méthode repose sur des notions de compatibilités entre éléments des structures ainsi que des critères de distances entre éléments. Ces techniques sont capables de détecter des événements tels que des permutations circulaires, des charnières (flexibilité) et des répétitions de motifs structuraux. Finalement nous proposons une nouvelle approche dans l'analyse fine de structures afin de faciliter la recherche de régions divergentes entre structures 3D fortement similaires. / This thesis focusses on local and global similarities and divergences inside protein structures. First, structures are scored, with criteria of similarity and distance in order to provide a supervised classification. This structural domain classification inside existing hierarchical databases is possible by using dominances and learning. These methods allow to assign new domains with accuracy and exactly. Second we focusses on local similarities and proposed a method of protein comparison modelisation inside graphs. Graph traversal allows to find protein similar substructures. This method is based on compatibility between elements and criterion of distances. We can use it and detect events such that circular permutations, hinges and structural motif repeats. Finally we propose a new approach of accurate protein structure analysis that focused on divergences between similar structures.

The subject of this diploma thesis is the design and assessment of main load-bearing elements od the steel structure of shopping gallery in Hodonín. Part of floor plan is rectangular and rest of it is half-circled. Object's dimensions are 7é m x 147,75 m (and roof overhang 1,5 m on each side), the height of the ridge is 13,43 m and the height of the roof's dome is 22,70 m. It's a two-storey building. The load-bearing structure consist of pin-suported columns, in this case there is max. 8,5 m distance between them in direction of main frame. The distance between main frames is 9 m. The spatial rigidity of the structure is ensured with floor slabs and system of bracings. The cladding consists of sandwich panels, roof's fanlights and dome of glazed areas. Most of elements are made of S355 steel.