Response Modification of Buildings and Bridges: Comparative Studies in Seismic Control
This thesis presents the results of research to evaluate the effectiveness of modern control strategies for the mitigation of earthquake induced hazards in building and bridge structures. Through a numerical example, a six story building structure with magnetorheological (MR) dampers on the lower two floors is used to evaluate the performance of a number of recently proposed semi-active control algorithms. The semi-active control algorithms considered include the Lyapunov controller, decentralized bang-bang controller, modulated homogenous friction algorithm, and a clipped optimal controller. Through simulation of the building structure using the El Centro earthquake, the reductions in inter-story drifts, absolute accelerations, and relative displacements are examined and compared for each semi-active control algorithm.
In addition to the application of control for a building structure, control of a bridge structure is studied using purely passive, active, and semi-active control strategies. Linear and nonlinear models are developed for a multi-span simply supported bridge. For the nonlinear bridge model, two models, the bilinear and the Bouc-Wen, are considered to represent the nonlinear behavior of the bearings. Through simulation, the behavior of each bearing model is compared. A linear bridge model as well as a nonlinear bridge model using the bilinear bearing model are used for the control study. Several device placement location cases are considered to determine the most effective placement of devices. Using synthetic ground motion records generated based on a modified approach to the spectrum compatible ground acceleration approach, the bridge models are simulated for each control strategy. Furthermore, bridge structural responses and bearing and control forces are compared for each control algorithm. The most effective device placement is chosen and the effectiveness of the purely passive, active, and semi-active control devices are compared.
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