Seismic Control of Structures Based on the Controllability and Stability of the Controlling System Criteria

Authors

Faculty of Civil Engineering. University of Tabriz, Tabriz, Iran.

10.22034/ceej.2024.62032.2363

Abstract

In order to mitigate seismic responses in structures, significant attention has been directed towards efficient vibration control systems, garnering interest from numerous researchers. This paper investigates the influence of controllability and control system stability. To this end, structural models with three, six, ten, and twenty-one stories were selected and equipped with Chevron braces, viscous fluid dampers, and active regulators, representing uncontrolled, passive-controlled, and hybrid-controlled structures. The structural motion equations were then formulated in state space representation, enabling assessment of the controllability, stability, or instability of the control system. The linear quadratic regulator algorithm was employed to compute the state feedback gain matrix and actuator response, thereby stabilizing the hybrid control system. MATLAB was utilized to simulate the state space equations and the ground motion acceleration time history, facilitating the extraction of seismic responses for the selected models. Analysis of floor and brace displacements, damper forces, and actuator responses revealed that unstable control systems exhibited divergent behavior and response of braces and dampers during earthquakes. Stabilization of the control system through Chevron braces effectively reduced seismic responses in certain floors, while the active regulator to some extent diminished seismic displacement across all floors. Overall, the results indicate that employing a sufficient number of braces, dampers, and actuators in a stabilized hybrid control system leads to convergence in the response of braces and dampers, resulting in a proper decrease in seismic displacement for both braces and floors.

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