Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Optimization of Isolators Between Floors of a High-Rise Building(01. Izmir Institute of Technology, 2024) Sönmez, Berkan; Turan, Gürsoy; Turan, Gürsoy; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyEarthquake vibrations are natural phenomena that can cause tremors on the ground surface and lead to serious loss of life and property. Especially large-scale earthquakes have the potential to significantly damage infrastructure systems and the durability of structures. Several strategies are available to reduce these damages and increase the resistance of structures to earthquakes. One of these strategies is the implementation of seismic isolators. Seismic isolation minimizes earthquake damage to structures. The main purpose of the study is to examine the effectiveness of the seismic isolator being installed at various story levels of 3D 20-story steel building model. The building had two sets of 20 evaluation models, each with a different isolator story. The first set had identical evaluation models, except for the isolation story which is incremented in each model. The second set is similar to the first set except that the lower stories are strengthened by shear walls. The goal was to determine the best dimensions for the isolator to minimize the inter-story drift values. For this purpose, a set of 12 earthquake records are selected. These records are scaled according to the determined design spectrum. The optimization is performed for one of these earthquake records. Nonlinear dynamic analyses are carried out to evaluate the building model responses for all 12 earthquake records. Response values such as story shear forces and story drift ratios were analyzed and interpreted. This analysis will contribute to a better understanding of the impact of isolators with optimization methods on structural performance.Master Thesis Optimization of Active Control for a Low-Rise Building(01. Izmir Institute of Technology, 2023) Bishtawi, Nabil; Turan, Gürsoy; Turan, Gürsoy; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThis study proposed optimization procedures to design an LQR controller for an active tuned mass damper on a 10-story structure. For the optimization, two multiobjective-function problems were formulated. The number of objective functions in both problems was equal to the number of stories, and they measured the ratio of controlled to uncontrolled drift. Optimizations of the ATMD have been realized by utilizing 28 near-field earthquake records with pulse ground motion. The performance of the resulting controller was assessed using five performance indices by utilizing 96 earthquakes comprised of near field with a pulse, near field without a pulse, and far-field records. The first optimization problem has no bounds on the magnitude of the applied force. Frequency analysis has been used along with time domain analysis to assess and figure out the characteristics of the controlled structure. The results indicate that a high amount of active force is needed. Several methods were tested to find the most effective way to decrease the needed actuator's force while keeping a good performance index similar to the original model. In the second optimization problem, a limitation was considered for the applied force. In this problem, the time simulation and frequency analysis have been used as in the first one. The force limitation in this problem triggers a bang-bang action issue. Several low-pass FIR filters have been tested against the issue, resulting in a better understanding of the originating reason for the bang-bang action and the filters' effect on the controller. To decrease the number of sensors used for the feedback system Kalman filter has been used. The output of Kalman filter was the same as the original system. The robustness of the controller was assessed by changing the characteristics of the uncontrolled structure and comparing it with the original model. It turns out that the optimized LQR-ATMD is robust.