| Control techniques based on the method of sliding mode control (SMC) have been investigated for applications to active/hybrid control of seismic-excited linear, nonlinear and hysteretic civil engineering structures. Such applications include the use of active bracing systems, active mass dampers, active variable dampers, active variable stiffness systems, and other control devices. Based on numerical simulations and experimental results, it was demonstrated that the sliding mode control methods are robust and their performances are quite remarkable. In this dissertation, sliding mode control methods are further extended by introducing a compensator in the design of the controller. The incorporation of a compensator provides a convenient way of making trade-offs between the control efforts and selected response quantities of the structure through the use of linear quadratic optimal control theory. In addition to full-state feedback controllers, a systematic design procedure for static output feedback controllers, using only a limited number of sensors installed at strategic locations without an observer, is presented to facilitate the practical implementations of active/hybrid control systems.; Civil engineering structures usually involve excessive degrees of freedom and, hence, the controller design based on the full-order system is quite involved. In this dissertation, a method for reducing the complex building structure into a manageable system, referred to as the reduced-order system, is presented. Then, the controller is designed based on the reduced-order system, referred to as the reduced-order controller. Extensive simulation results demonstrate that the performance of the reduced-order controller compares favorably with that of the full-order controller, if sufficient vibrational modes of the structure are taken into account in the reduced-order system. The introduction of a compensator in sliding mode control and the design of reduced-order controllers for complex structures presented in this dissertation represent a significant contribution to the state-of-the-technology in active/hybrid control of civil infrastructures. |
