Al-Fahdawi, Omar Ahmed Saleh (2019-03). Semi-Active Adaptive Control of Coupled Structures for Seismic Hazard Mitigation. Doctoral Dissertation.
The research presented in this dissertation examines innovative structures connected with smart control devices driven by adaptive control methods. The research focuses on understanding the dynamics of coupled structures and evaluating the merits of adaptive control in enhancing the seismic performance of these structures and dealing with uncertainties. Coupled structures is recognized as an effective strategy to protect civil structures from seismic excitations. Coupling of adjacent structures has proved to offer functional benefits such as the potential for shifting the buildings' natural frequencies, likely leading to a reduction in the natural period of vibration. Structural performance is further enhanced by implementing energy-dissipative devices to connect adjacent buildings to minimize the seismic structural responses. One of the main challenges to control civil structures is the high uncertainty involved throughout their lifetimes. Adaptive control promises to deal with changes in structures' characteristics, such as seismic-induced damage. The simple adaptive control method, which is a reference-model following scheme, is used in the current research to improve the seismic behavior of adjacent buildings connected by structural links where control devices are implemented. The philosophy of the simple adaptive control method is that an actual system (often called plant) can be forced to track the behavior of pre-determined trajectories through adjustable adaptive gains. The effectiveness of the simple adaptive controller in reducing the seismic responses is compared with other adaptive and non-adaptive control methods. The results reveal that the simple adaptive controller is effective in alleviating the structural responses and dealing with uncertainties of coupled structures with both linear and nonlinear behavior. The results also show that the coupling strategy is viable for reducing the structural responses under seismic excitations.