Vibration control of flexible structures
Abstract
Control algorithms were presented for vibration control of structures excited by environmental loads. The first control algorithm based on the eigensystem assignment, for an aggregated system with selected modes retained, was formulated and a procedure based on balanced model realization, for computing the modal disturbance index (MDI), was adopted for ranking the modes in the contribution of dynamic response due to disturbance. The modes retained in the aggregated system were selected based on this ranking. The controller gain was obtained by solving the aggregated Sylvester equation with specified modal control weighting (MCW) which is a measure of controllability of modes to be controlled. The aggregated eigensystem assignment (AEA) controller can be applied for partial or sequential assignment of any combination of real and complex conjugate pairs of eigenvalues without altering the rest eigenspectrum of the full system. To evaluate the efficiency and performance of the AEA controller, numerical examples of vibration control for seismically excited structure which is equipped with base isolation system or active tendon system were illustrated. The other control algorithm was formulated for a second-order dynamic system. Collocated sensor/actuator pairs and feedback controller which is described by a set of second-order dynamic equations were assumed for the development of the dynamic controller. The feedback may be acceleration, velocity, or displacement alone or any of their combinations. The controller gains were determined numerically by minimizing the root-mean-square value of certain specified response of the structure excited by white noise. Applications of the controller design were presented. First, the controller was used for active base isolation of a tall building modeled as a shear beam and behaves like a virtual vibration absorber which damps out the excitation energy. In the second, the procedure was applied to the design of an active mass damper (AMD) for a torsionally coupled building. Results on control performance and effectiveness for different eccentric locations of the rotation and inertia axes of this building were presented and discussed. In the third, an AMD controlled high rise building under wind load was illustrated.
Degree
Ph.D.
Advisors
Yang, Purdue University.
Subject Area
Aerospace materials|Mechanical engineering
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