| Summary: | 博士 === 國立中央大學 === 土木工程研究所 === 100 === An alternative design method of sliding mode control is proposed for practical implementation on nonlinear isolated bridges in this study. The proposed controller explicitly reveals the robustness of sliding mode control to parametric uncertainties of structures. The effectiveness of sliding mode control is studied numerically and systematically for an isolated viaduct under extreme earthquakes. The results show that the sliding mode control with appropriate sliding surfaces, obtained by parametric study, achieves outstanding control performance compared to the conventional LQR control and viscous damping passive control. Additionally, the performance of active control can be considerably fulfilled by the semi-active control with variable dampers using the proposed control algorithm.
Compared with typical isolated bridges, the irregular isolated bridge has more poles of sliding surface, which dominates the dynamic characteristics of the controlled system and should be determined for the sliding mode control. The effectiveness of sliding mode control on the seismic response of an isolated bridge with columns of irregular heights, which exhibit hysteretic behaviors at both the columns and isolators, is studied. However, because many parameters of sliding surface for the irregular isolated bridge should be determined, it is difficult to find the optimum parameters efficiently and comprehensively by parametric study. The particle swarm optimization-simulated annealing (PSO-SA) hybrid searching algorithm which is an optimization technique, is employed, modified and shown to outperform the particle swarm optimization algorithm and a parametric approach in finding the best sliding surface. Numerical simulations reveal that the sliding mode control together with the modified PSO-SA hybrid searching algorithm provides a simple and powerful technique for more effectively controlling the nonlinear seismic responses of the irregular isolated bridge.
A series of shaking table tests were conducted to study the semi-active control with MR dampers for the isolated bridges. A two-story shear-type structure assembled by steel plates and rolled shapes and an isolated structure with columns of irregular heights assembled by steel plates and two pairs of RPS on the top of both columns are designed to simulate the behavior of typical and irregular isolated bridge. The feasibility of the semi-active control system with a MR damper commanded by the continuous sliding mode control algorithm is verified in practical implementations for structures undergoing elastic or inelastic behavior to ground motions.
|
|---|
