| The thesis presents a hybrid control system, which consists of viscous fluid dampers and servovalve-controlled hydraulic actuators supported by K-braces on a seismic-resistant structure. This research focuses on improving the applicability of full-scale active and hybrid control systems, and comprises modeling and evaluation of the hybrid system, seismic observer development and optimal placement of control devices.; The significance, history, typical systems and challenges of structural control are discussed first. Second, an analytical model of structures with hybrid bracing control is formulated considering dynamics of the components, interaction between each component, as well as arbitrary number and arbitrary location of control devices. Third, effects of actuator dynamics on open-loop stability and closed-loop response of active and hybrid systems are studied. A method for actuator stabilization is developed and effectiveness of this hybrid control is evaluated. Fourth, a seismic observer is established to handle insufficient sensors and acceleration measurements in seismic response control. Fifth, based on extending stochastic theory to seismic response of controlled structures, a general optimization problem for control device placement is formulated and solved statistically. Finally, achievements of and conclusions from this research work are outlined.; This study indicates that actuator dynamics significantly influences control system performance, that hybrid control systems are more effective than active and passive control systems, that a seismic observer works as effectively as full-state sensing yet simplifies sensing and data-acquisition system, and that an optimally-placed hybrid control system attains superior performance in that far less active control force is required. |
