Multi-objective control for civil engineering structures

In this dissertation, several multi-objective optimal control strategies are proposed and their applications to active control of civil engineering benchmark structures are presented. Two classes of excitations (loadings) have been considered, including a class of excitations with a specified energy bound (EB) and another class of excitations with a specified peak bound (PB). Various objective functions have been optimized where the constraints (or penalties) are the peak values of another set of quantities, including the peak control resources and responses. The objective functions considered include: (i) the sum of weighted peak response quantities, (ii) the upper bound of H₂ performance, and (iii) the upper bound of H_∞ performance.; State feedback and dynamic output feedback controllers for all control strategies are derived and presented. The design syntheses of these control strategies are developed and formulated within the framework of linear matrix inequalities (LMIs), so that the LMI toolbox in MALAB can be used effectively and conveniently. These control strategies are applied to a long-span cable-stayed benchmark bridge subject to earthquakes and a wind-excited 76-story benchmark building to illustrate their applicability to practical problems. Simulation results indicate that the performances of these proposed controllers are uniformly better than that of the LQG sample controller. It is shown that these new control strategies are viable and effective for applications to civil engineering structures.; Two optimal design methodologies are presented for passive energy dissipation devices (EDDs) based on active control theories, including H_∞ and H₂ performances, respectively. The optimal design methodologies presented are capable of determining the optimal locations and the corresponding capacities of EDDs. Emphasis is placed on the application of linear matrix inequality (LMI) for the effective design of passive EDDs using the popular MATLAB toolboxes. One important advantage of the proposed approaches is that the computation of the structural response is not needed in the design process. The proposed optimal design methodologies have been applied to different buildings subject to either the earthquakes or strong winds to demonstrate the advantages of the proposed design methodologies over the conventional equal capacity design.