Wavelet PSO-Based LQR Algorithm for Optimal Structural Control Using Active Tuned Mass Dampers

This study presents a new method to find the optimal control forces for active tuned mass damper. The method uses three algorithms: discrete wavelet transform (DWT), particle swarm optimization (PSO), and linear quadratic regulator (LQR). DWT is used to obtain the local energy distribution of the motivation over the frequency bands. PSO is used to determine the gain matrices through the online update of the weighting matrices used in the LQR controller while eliminating the trial and error. The method is tested on a 10-story structure subject to several historical pulse-like near-fault ground motions. The results indicate that the proposed method is more effective at reducing the displacement response of the structure in real time than conventional LQR controllers. INTRODUCTION With the development of construction techniques, it is possible to build large-span bridges, pipelines, dams, and other essential structures in seismically active regions or through active faults. The strong earthquakes, which have occurred in recent years, have resulted in severe damage to the near-fault buildings and bridges and loss of life. Hence, research on the characterization and analytical modeling of near-fault seismic ground motions, as well as the study of their influences on the performance of engineering structures, has become an active area in both seismology and the earthquake engineering field [1-14]. Mitigating the seismic responses of major structures such as tall buildings, wind sensitive bridges, and poten-tially susceptible structures has been studied comprehensively over the years [1519]. The passive tuned mass damper (PTMD) is effective in reducing the vibration of structures caused by earthquakes with limited band frequency [20-21]. TMD system relies on the damping forces introduced through the inertia force of a secondary system attached to the main structure by spring and dashpot to reduce the response of the main structure. Lin et al. (2010) used initially accelerated passive TMD to suppress structural peak responses under near-fault ground motions [22]. This study showed that the PTMD initial velocity is effective in vibration control of structures under pulse-like ground motion. However, due to the limitation of PTMD stroke as well as the applied force, the initial velocity cannot be too large in practical applications. To overcome these shortcomings, the active control can be applied to TMD. Extensive reviews on using the active tuned mass damper (ATMD) can be found in civil engineering literature [23-24]. Chey et al. (2010) proposed a semi-ATMD to mitigate the response of structures. In this study, the stiffness of the resettable device design was combined with rubber bearing stiffness [25]. Moreover, some researchers developed an advanced control law for Semi-Active resettable devices [26]. Also, other researcher proposed a new resettable device control to reduce the response of structures [27-28]. Unal Aldemir Istanbul Technical University, Earthquake Engineering and Disaster Management Institute, Istanbul, Maslak 34469, Turkey [email protected] Proceedings of the ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2015 August 2-5, 2015, Boston, Massachusetts, USA