Search

Com o passar dos anos e a demanda por estruturas cada vez mais esbeltas e de menor custo, tem-se a necessidade de desenvolvimento de sistemas de controle de vibrações eficazes. Dispositivos de dissipação de energia passivos são bem conhecidos devido ao seu bom desempenho para controle de vibrações em edifícios sujeitos a excitações dinâmicas. O amortecedor de massa sintonizado (Tuned Mass Damper - TMD) é um dos dispositivos passivos mais antigos e mais usados para controle de vibrações em edifícios em todo o mundo. No entanto, os melhores parâmetros em termos de rigidez e amortecimento, assim como as melhores posições dos TMDs a serem instalados na estrutura permanecem sendo difícil de determinar, especialmente quando mais de um TMD precisa ser instalado, ou seja, quando há a necessidade de se instalar múltiplos amortecedores de massa sintonizados (Multiple Tuned Mass Dampers - MTMD). Assim, a otimização de parâmetros, quantidade e posições de MTMD é uma área que vem sendo estudada nos últimos anos, buscando projetos ótimos de tal dispositivo, para minimização da resposta dinâmica estrutural. Portanto, nesta tese, propõe-se uma metodologia para otimização simultânea de parâmetros e posições de MTMD em edifícios submetidos a sismos. É importante ressaltar que, diferente da maioria dos trabalhos da literatura, a metodologia de otimização proposta nesta tese considera as incertezas presentes nos parâmetros estruturais, na carga dinâmica (sismos) e também nos parâmetros dos MTMD, ou seja, propõem-se uma metodologia de otimização robusta. Desta forma, obtém-se um projeto ótimo robusto, ou seja, um projeto de MTMD que não é sensível às variações dos parâmetros envolvidos no comportamento dinâmico do sistema. Para fins de ilustração, a metodologia proposta é aplicada em um prédio de 10 andares, confirmando sua eficácia. Adicionalmente, novamente com o objetivo de confirmar a eficácia da metodologia proposta para projeto ótimo robusto de MTMD, avalia-se a resposta dinâmica do edifício em estudo submetido a registros sísmicos reais e equipado com os MTMD otimizados pelo método proposto, confirmando novamente a eficácia da metodologia desenvolvida. Assim, acredita-se que a metodologia proposta pode ser utilizada como uma ferramenta promissora para o projeto de MTMD. Over the years and with the demand for increasingly slender and lower cost structures, there is a need to develop effective vibration control systems. Passive energy dissipation devices are well known for their good performance in controlling vibrations in buildings subject to dynamic excitation. The tuned mass damper (TMD) is one of the oldest and most used passive devices for vibration control in buildings around the world. However, the best parameters in terms of stiffness and damping, as well as the best positions of the TMDs to be installed in the structure remain difficult to determine, especially when more than one TMD needs to be installed, that is, when there is a need to install multiple tuned mass dampers (MTMD). Thus, the optimization of parameters, quantity and positions of MTMD is an area that has been studied in recent years, seeking optimal designs of such a device, to minimize the structural dynamic response. Therefore, in this thesis, a methodology is proposed for the simultaneous optimization of MTMD parameters and positions in buildings subjected to earthquakes. It is important to emphasize that, unlike most works in the literature, the optimization methodology proposed in this thesis considers the uncertainties present in the structural parameters, in the dynamic load (earthquakes) and also in the MTMD parameters, that is, a methodology for robust optimization. In this way, an optimal robust design is obtained, that is, an MTMD design that is not sensitive to variations in the parameters involved in the dynamic behavior of the system. For illustration purposes, the proposed methodology is applied to a 10-story building, confirming its effectiveness. Additionally, again with the objective of confirming the effectiveness of the proposed methodology for robust MTMD design, the dynamic response of the building under study is evaluated, subjected to real seismic records and equipped with the MTMD optimized by the proposed method, again confirming the effectiveness of the methodology developed. Thus, it is believed that the proposed methodology can be used as a promising tool for the MTMD design.

Earthquakes can cause vibration problems in many types of structures, generating large displacements. The interstory drift is a design criterion very used in seismic analysis and the structural control is an alternative to reduce these displacements and improve the performance of these structures adapting them to the imposed criteria. TMD is a device widely used due to the simple principle of operation and many successful applications in real life practice. This paper investigates the use of optimized TMD for reduction of maximum horizontal displacement at the top floor and interstory drift of a steel building under seismic excitation considering three scenarios: single TMD at the top floor; MTMD horizontally arranged at the top floor; and MTMD vertically arranged on the structure. By a metaheuristic optimization algorithm, the parameters and positions of the devices are obtained. Three real and one artificial earthquakes are employed in the simulations. The results showed that all proposed scenarios are efficient in reducing top floor response and interstory drift to values below of the interstory drift limits allowed by the standard code consulted. However, Scenario 2 presented the best reduction for the top displacement and interstory drift to the critical floor for the worst earthquake considered.

Based on the notions of spectrum sensitivities, proposed by us earlier, we develop a novel optimization approach to deal with robustness in the closed-loop eigenvalues for partial quadratic eigenvalue assignment problem arising in active vibration control. A distinguished feature of this new approach is that the objective function is composed of only the system and the closed-loop feedback matrices. It does not need an explicit knowledge of the eigenvalues and eigenvectors. Furthermore, the approach is applicable to both the state-feedback and derivative feedback designs. These features make the approach viable to design an active vibration controller for practical applications to large real-life structures. A comparative study with existing algorithms and a study on the transient response of a real-life system demonstrate the effectiveness, superiority, and competitiveness of the proposed approach.