A Seismic Base Isolation Review And Bibliography Example

Seismic isolation is a widely accepted control strategy to protect building against earthquakes. The seismic isolation control is a technique that employs a flexible element at the base of a building and allows the resonant frequency of this building being shifted away from the dominant frequency in earthquake excitations. However, large base displacements resulting from the increased flexibility of the seismic isolation system can potentially exceed the design limit of the building subjected to severe earthquake loading. Thus, design codes recommend equipping additive damping devices along with the seismic isolation bearings to lower the base displacements. In this study, a new design method of seismic isolation is developed using the linear quadratic algorithm that concurrently provides the terms of stiffness and damping coefficient. This design method facilitates the linear quadratic regulator control algorithm with output feedback. For a multiple-degree-of-freedom structure, the shear force provided by seismic isolation can be separated from the superstructure and formed as a control input. This control input is a function of the relative displacement and velocity at the isolation layer with a constant stiffness quantity and damping coefficient. This control algorithm provides the opportunity of deriving these two constants. Moreover, the derivation of isolation stiffness and damping coefficient depends on the user-defined weightings that allow adjusting performance of the isolated building in this control algorithm. One example is provided with eight-story buildings as the superstructures. As seen in the result, the root-mean-square responses are quite compatible between isolated buildings with linearly and nonlinearly isolated bearings. Therefore, the proposed method is useful for designing seismic isolation based on a multiple-degree-of-freedom building.

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