The effectiveness of seismic retrofitting applied to enhance seismic performance was assessed for a five-story reinforced concrete (RC) flat-slab building structure in the central United States. In addition to this, an assessment of seismic fragility that relates the probability of exceeding a performance level to the earthquake intensity was conducted. The response of the structure was predicted using nonlinear static and dynamic analyses with synthetic ground motion records for the central U.S. region. In addition, two analytical approaches for nonlinear response analysis were compared. FEMA 356 (ASCE 2000) criteria were used to evaluate the seismic performance of the case study building. Two approaches of FEMA 356 were used for seismic evaluation: global-level and member-level using three performance levels (Immediate Occupancy, Life Safety and Collapse Prevention). In addition to these limit states, punching shear drift limits were also considered to establish an upper bound drift capacity limit for collapse prevention. Based on the seismic evaluation results, three possible retrofit techniques were applied to improve the seismic performance of the structure, including addition of shear walls, addition of RC column jackets, and confinement of the column plastic hinge zones using externally bonded steel plates. Finally, fragility relationships were developed for the existing and retrofitted structure using several performance levels. Fragility curves for the retrofitted structure were compared with those for the unretrofitted structure. For various performance levels to assess the fragility curves, FEMA global drift limits were compared with the drift limits based on the FEMA member-level criteria. In addition to this, performance levels which were based on additional quantitative limits were also considered and compared with FEMA drift limits.

Reinforced concrete frames display nonlinear behavior both due to its composite nature and the material properties of concrete itself. The yielding of the reinforcement, the non-uniform distribution of aggregates and the development of cracks under loading are the main reasons of nonlinearity. The stiffness of a frame element depends on the combination of the modulus of elasticity and the geometric properties of its section - area and the moment of inertia. In practice, the elastic modulus is assumed to be constant throughout the element and the sectional properties are assumed to remain constant under loading. In this study, it is assumed that the material elasticity depends on the reinforcement ratio and its distribution over the section. Also, the cracks developing in the frame element reduces the sectional properties. In case of linear analysis, the material and sectional parameters are assumed to be constant. In practice, the modulus of elasticity E is a predefined value based on previous experiments and the moment of inertia I is assumed to be constant throughout the analysis. However, in this study, E and I are assumed to be combined. In other words, they cannot be separated from each other throughout the analysis. These two parameters are handled as a single parameter as EI . This parameter is controlled by the reinforcement ratio and its configuration, sectional properties and deformation of the member. Two types of analysis, namely a sectional and a finite element analyses, are used in this study. From the sectional analysis, the parameter EI is calculated based on the sectional geometry, material properties and the axial load applied on the section. The parameter EI is then used in the finite element analysis to calculate the sectional forces and the nodal displacements. For the nonlinear analysis, the Newton-Raphson iterative approach is followed until convergence is obtained.

The analysis procedures employed in earthquake engineering can be classified as linear static, linear dynamic, nonlinear static and nonlinear dynamic. Linear procedures are usually referred to as force controlled and require less analysis time and less computational effort. On the other hand, nonlinear procedures are referred to as deformation controlled and they are more reliable in characterizing the seismic performance of buildings. However, there is still a great deal of unknowns for nonlinear procedures, especially in modelling the reinforced concrete structures. Turkey ranks high among all countries that have suffered losses of life and property due to earthquakes over many centuries. These casualties indicate that, most regions of the country are under seismic risk of strong ground motion. In addition to this phenomenon, recent studies have demonstrated that near fault ground motions are more destructive than far-fault ones on structures and these effects can not be captured effectively by recent nonlinear static procedures. The main objective of this study is developing a simple nonlinear dynamic analysis procedure which is named as &ldquo / Dynamic Pull Analysis&rdquo / for estimating the seismic response of multi degree of freedom (MDOF) systems. The method is tested on a six-story reinforced concrete frame and a twelve-story reinforced concrete frame that are designed according to the regulations of TS-500 (2000) and TEC (1997).

Conventional methods used in the structural analysis are usually insufficient for the analysis of historical structures because of the complex geometry and heterogeneous material properties of the structure. Today&rsquo / s computing facilities and methods make FEM the most suitable analysis method for complex structural geometry and heterogeneous material properties. Even the shrinkage, creep of the material can be considered in the analysis. Because of this reason Finite Element Method (FEM) is used to analyze such structures. FEM converts the structure into finite number of elements with specific degree of freedoms and analyses the structure by using matrix algebra. However, advanced FEM methods considering the inelastic and time dependent behavior of material is a very complex and difficult task and consumes considerable time. Because of this reason, to analyze every historical structure is not feasible by applying advanced inelastic FEM, whereas elastic FEM analysis at low load levels is very helpful in understanding the behavior of the structure.The analysis of a masonry gate in the historical city, Hasankeyf is the case study of this thesis. Different common software are used in FEM to compare the stresses, deformations, modal shapes etc. of the same structure. Besides the inelastic behavior of the structure is investigated and compared with the elastic behavior of the structure. The study is intended to show that at the low load levels elastic FEM analysis is sufficient to understand the response of the structure and is preferable to the inelastic FEM analysis unless a very complex analysis is required

The purpose of this thesis is to investigate the inelastic action in the reinforced concrete frame-wall structures analytically and with that analysis to follow the plastic formation of the structure. For this purpose, six mid-rise reinforced concrete buildings with frame-wall are modeled and analyzed to understand the effect of the height and base shear force ratio of the wall on the nonlinear interaction between reinforced concrete wall and frame members under static lateral loads and ground motion excitations. The parametric analysis is conducted by assuming planar response of the buildings under loadings. The buildings are generated considering the limit design concept suggested by Turkish Earthquake Code 2007 and Turkish Standards TS500, and the frame-wall members are modeled by using spread plasticity elements and fiber discretization of sections. In the analysis stage, each element section is divided into confined and unconfined regions for detailed modeling of the building by using OpenSEES nonlinear finite element program. Two dimensional analyses are conducted under static and dynamic loadings. For static pushover analyses, three different lateral load cases (Triangular, Uniform and First-Mode Lateral Load Patterns) are considered. For dynamic analyses, eight different ground motions are used. These ground motions are scaled to the corresponding design response spectrum suggested by Turkish Earthquake Code 2007 by using RSPMATCH program. Using the result of the complex and simplified analyses, inter-story drift ratios, plastic rotations and internal force distributions of the buildings are investigated.

The effectiveness of seismic retrofitting applied to enhance seismic performance was assessed for a five-story reinforced concrete (RC) flat-slab building structure in the central United States. In addition to this, an assessment of seismic fragility that relates the probability of exceeding a performance level to the earthquake intensity was conducted. The response of the structure was predicted using nonlinear static and dynamic analyses with synthetic ground motion records for the central U.S. region. In addition, two analytical approaches for nonlinear response analysis were compared. FEMA 356 (ASCE 2000) criteria were used to evaluate the seismic performance of the case study building. Two approaches of FEMA 356 were used for seismic evaluation: global-level and member-level using three performance levels (Immediate Occupancy, Life Safety and Collapse Prevention). In addition to these limit states, punching shear drift limits were also considered to establish an upper bound drift capacity limit for collapse prevention. Based on the seismic evaluation results, three possible retrofit techniques were applied to improve the seismic performance of the structure, including addition of shear walls, addition of RC column jackets, and confinement of the column plastic hinge zones using externally bonded steel plates. Finally, fragility relationships were developed for the existing and retrofitted structure using several performance levels. Fragility curves for the retrofitted structure were compared with those for the unretrofitted structure. For various performance levels to assess the fragility curves, FEMA global drift limits were compared with the drift limits based on the FEMA member-level criteria. In addition to this, performance levels which were based on additional quantitative limits were also considered and compared with FEMA drift limits.

At the design stage, column-beam connections of steel structures are assumed as fully rigid or as hinges, and the design is completed with these assumptions. On the other hand, in practice, steel column-beam connections show neither fully rigid nor fully hinge behaviour, and the characteristic behaviour of the connections lies between these two special cases. Performing realistic calculation of these forces and knowing the behaviour of structures close to reality will decrease life and goods losses to the minimum level in a probable of earthquake to be encountered in the future. &nbsp / In this study, seismic performance of 2-D steel frames were evaluated by Capacity Spectrum Method proposed in the ATC 40 document published in 1996. A new computer program was developed in order to define all geometric and loading data and to perform nonlinear analysis of rigid and semi rigid steel frames for which the performances will be evaluated. In case studies, 3-Floor Steel Frames that have different bay numbers were investigated in various forms according to the rigid and different semi rigid connection types. In addition, the performances these frames for various seismic regions and soil conditions were compared. According to the results, it was observed that semi rigidly connected frames are under the effect of smaller ground acceleration have greater displacement values. As a consequence of this ductile and energy dissipative response, it was seen that the stresses in the members of frame become considerably small, relative to the stresses in the rigid frames&rsquo / . Furthermore, the performances of semi-rigid frames can be affected negatively beyond such a low rigidity. Consequently, the most convenient design should be made according to the seismic and soil region where the structure to be constructed by performing the necessary studies on the connection details in order to achieve desired performance, serviceability and optimum member criteria.

In transport of fluids or even as structural elements, cylindrical shells are widely used in several segments of structure engineering. The understanding of the behavior of this type of structure along a trajectory of equilibrium resultant of a description of historical loading of different natures and, consequently, is important in the definition of the real load capacity of the ducts. In this work, a finite element for geometric and threedimensional nonlinear analyses of pipes is developed. Taking into account the nature of the analysis, proper measure of tension and deformation that are compatible with states of large deformations and displacements are studied. The Total Lagrangean formulation is adopted, but the constitutive relationships used are linear. The developed computational implementation uses a three-dimensional finite element of pipe with 2 or 3 nodes, compatible with the state of great deformations and displacements, and, also, incorporating the movements of rigid body of the structure.In order to map the nonlinear trajectories of equilibrium, using some methodologies proposed in the literature, a structure of Object-Oriented Programming is used. It allows the application of different techniques of incremental and iterative analysis integrated to the implementation of the aforementioned finite elements.Aiming to validate the formulation, the results obtained by using the program here developed are evaluated through their comparison with analytical solutions and previously published results. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No transporte de fluidos ou mesmo como elementos estruturais as cascas cilíndricas são largamente utilizadas em diversos segmentos da engenharia civil. A compreensão do comportamento desse tipo de estrutura ao longo de uma trajetória de equilíbrio resultante de um histórico de carregamento de diferentes naturezas é importante na definição da real capacidade portante dos dutos. Neste trabalho, desenvolve-se um elemento finito para análises geometricamente não lineares tridimensionais de tubos. Levando-se em consideração a natureza da análise, são estudadas medidas adequadas de tensão e deformação, compatíveis com regimes de grandes deformações e deslocamentos. A formulação Lagrangeana Total é adotada, mas as relações constitutivas utilizadas são lineares. A implementação computacional desenvolvida emprega um elemento finito tridimensional de tubo com 2 ou 3 nós, compatível com o regime de grandes deformações e deslocamentos, incorporando, também, os movimentos de corpo rígido da estrutura. Com o objetivo de mapear as trajetórias não lineares de equilíbrio, utilizando-se algumas metodologias propostas na literatura, é usada uma estrutura de programação orientada a objetos, permitindo a aplicação de diferentes técnicas de análise incremental e iterativa integradas à implementação de elementos finitos supracitada. Visando validar a formulação, os resultados obtidos no programa desenvolvido são avaliados através da comparação com soluções analíticas e outras análises numéricas disponíveis na literatura.

Por epilepsia, são denominadas diversas condições neuronais patológicas caracterizadas pela ocorrência de atividade elétrica anormal de uma região do cortex que se difunde formando a crise epiléptica. Tais crises recorrentes possuem efeito relevante sobre a qualidade de vida, além de frequentemente possuírem efeito deletério gradativo sobre a capacidade cognitiva do paciente, sendo necessário tratamento e acompanhamento médico. Dentro das diversas condições epilépticas, existe o que é conhecido como epilepsia refratária, que é a condição em que o paciente não responde a nenhum medicamento anticonvulsivante. A alternativa para estes pacientes é a cirurgia, porém, diversas dificuldades como a localização do foco epiléptico e determinação da extensão da zona epileptogênica podem prejudicar as chances de sucesso deste procedimento. O eletroencefalograma (EEG) sempre foi muito utilizado na clínica neurológica, pois existem padrões de atividade neuronal facilmente observados que podem auxiliar no tratamento de diversas condições, incluindo a epilepsia. Nos últimos anos, vem se demonstrando interesse em cima de um certo padrão que ocorre em frequências antes ignoradas na análise clínica. Estes padrões recebem o nome de oscilações de alta frequência (HFOs). Este estudo teve por objetivo analisar sinais de EEG de pacientes de epilepsia adquiridos com frequência de aquisição suficientemente alta para a obtenção de informações a cerca da atividade em alta frequência através da detecção automática de HFOs, além da implementação de um método de análise temporal utilizando a Detrended Fluctuation Analysis (DFA). Os resultados mostram que segmentos distantes da ocorrência de uma crise apresentam média de coeficiente Alfa1 = 1,3587 e Alfa2 = 0,6165, enquanto segmentos durante a ocorrência da crise apresentam coeficientes Alfa1 = 1,4061 Alfa2 = 0,5107. Apesar das limitações do estudo, os resultados indicam ser possível identificar presença de atividade elétrica anormal, e o método utilizado pode evoluir para auxiliar o diagnóstico e planejamento de cirurgia em epilepsia. / By epilepsy, a diversity of pathological neuronal conditions characterized by the occurrences of abnormal electric activity in a cortex region that, when diffunded, causes epileptic seizures. Such recurrent seizures have relevant effects in life quality, and frequently are associated with irreversible damages in cognitive capacity, therefore treatment and medical caring is needed. Inside the classification of epilepsy there is an specific condition known as refractory epilepsy, in which the patient does not respond to anticonvulsant medications. The alternative to these patients is surgery, but the difficulties in determining the exact location of the epileptic focus and the extension of the epileptogenic zone may lead to lower chances of success. The electroencephalogram (EEG) is widely used on neurological clinic, as there are certain patterns of neuronal activity that are easily observed and may help treat a series of pathologies, including epilepsies. Over the last decade, a certain interest has been developed on a specific pattern occurring in frequency bands once ignored on clinical analysis. These patterns are called high frequency oscillations (HFOs). The objective of this study was to analyze EEG signals from patients with epilepsy, sampled with a high frequency, so that it is possible to obtain information on high frequency activity through the automatic detection of the HFOs, in addition to the implementation of a nonlinear analysis using Detrended Fluctuation Analysis (DFA). The results shows that segments distant to the occurrence of seizures have a mean value for Alfa1 = 1,3587 and Alfa2 = 0,6165, while segments during the occurrence of seizures have a mean value for Alfa1 = 1,4061 and Alfa2 = 0,5107. Despite study limitations, results indicates it is possible to identify presence of abnormal electric activity and the proposed method may evolve to help epilepsy diagnostic and surgical planning in epileptic patients.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-12-11T11:29:18Z No. of bitstreams: 2 Dissertação - Pedro Henrique Pedrosa de Melo - 2018.pdf: 47578131 bytes, checksum: 8fbf8b63ebd4d5db7f6f6223bd26712a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-12-12T10:37:34Z (GMT) No. of bitstreams: 2 Dissertação - Pedro Henrique Pedrosa de Melo - 2018.pdf: 47578131 bytes, checksum: 8fbf8b63ebd4d5db7f6f6223bd26712a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-12-12T10:37:34Z (GMT). No. of bitstreams: 2 Dissertação - Pedro Henrique Pedrosa de Melo - 2018.pdf: 47578131 bytes, checksum: 8fbf8b63ebd4d5db7f6f6223bd26712a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-10-22 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The present paper deals with the main subjects related to castellated steel beams, initially showing a brief review of the history of emergence and use of the world, highlighting the characteristics that favored the growth of use and the difficulties of its use. The main failure modes are characterized, highlighting the analytical procedures available in the literature to circumvent them, in order to propose a calculation procedure for the design. The proposed procedure is evaluated through the experimental result of four surveys. The work also presents numerical modeling, using Finite Element Method (FEM), for beams available in the technical literature, in order to complement the analysis of beam behavior during loading and to verify the validity of the proposed numerical model, mainly in relation to the analysis criteria adopted in the numerical model, such as von Mises stress distribution, isotropic hardening and tensile stress behavior of the steel using the multilinear graph, also available in the technical literature. The validity allows the proposed beams, with Anglo-Saxon geometry, Litzka and Peiner, to have reliability of analysis of the model, and for the proposed loading the Anglo-Saxon beam obtained greater resistance, mainly due to the small distance between the holes and also the lowest overall width of the aperture. The results of the numerical models, via MEF, showed good precision when compared to the experimental results, showing that MEF is an extremely useful tool for nonlinear analysis, provided the model is properly calibrated. Another important result is the resistance values presented by the proposed analytical procedure, which presents a good approximation to the actual values of the experiment and also the resistance values obtained in the proposed numerical models, and can be adopted for the practical dimensioning of these beams. / O presente trabalho aborda os principais assuntos relacionados às vigas alveolares casteladas, mostrando inicialmente uma breve revisão do histórico de surgimento e utilização pelo mundo, ressaltando as características que favoreceram o crescimento de utilização e quais as dificuldades de seu uso. Os principais modos de falha são caracterizados, ressaltando os procedimentos analíticos disponíveis na literatura para contorná-los, de forma a se propor um procedimento de cálculo para o dimensionamento. O procedimento proposto é avaliado por meio do resultado experimental de quatro pesquisas. O trabalho também apresenta uma modelagem numérica, via Método dos Elementos Finitos (MEF), para vigas disponíveis na literatura técnica, de forma a complementar a análise do comportamento das vigas durante o carregamento e também verificar a validade do modelo numérico proposto, principalmente em relação aos critérios de análise adotados no modelo numérico, como distribuição das tensões de von Mises, endurecimento isotrópico e comportamento tensão x deformação do aço por meio do gráfico multilinear, também disponível na literatura técnica. A validade permite que as vigas propostas, com geometria Anglosaxão, Litzka e Peiner, possuam confiabilidade de análise do modelo, sendo que para o carregamento proposto a viga Anglo-saxão obteve maior resistência, devido principalmente pela pequena distância entre os furos e também a menor largura total da abertura. Os resultados dos modelos numéricos, via MEF, apresentaram boa precisão quando comparado aos resultados experimentais, mostrando que que o MEF é uma ferramenta extremamente útil para análises não-lineares, desde que o modelo esteja devidamente calibrado. Outro resultado importante são os valores de resistência apresentados pelo procedimento analítico proposto, ao qual apresenta boa aproximação aos valores reais do experimento e também dos valores de resistência obtidos nos modelos numéricos propostos, podendo, assim, ser adotado para o dimensionamento prático dessas vigas.