Abstract
Conventional base isolation (BI) techniques require a great reduction in the fundamental frequency of the system in order to mitigate the structural dynamic responses due to earthquake excitations. However, the resulting base displacements are large and can cause utility connection problems, rendering BI inadequate for retrofitting. This paper proposes a vibration control system (VCS) that can be used as a supplement to the conventional BI to increase the effective damping, and thus reduce the required base displacements. A novel passive negative stiffness (NS)-based vibration absorber, based on the KDamper, is implemented in parallel to a BI. The design of the VCS follows a constrained optimization approach that accounts for geometrical and manufacturing limitations. The NS is realized with a realistic displacement-dependent mechanism that generates controlled NS. The VCS is designed for various soil-types in order to determine its effectiveness and soil-structure-interaction (SSI) effects are accounted with respect to the soil-type. The earthquake excitation input is selected according to the EC8 by generating a database of artificial accelerograms for each ground type. Finally, the VCS is compared to a conventional BI, and based on the numerical results obtained, the VCS is an effective alternative to BI and a possible retrofitting option.
Highlights
The fundamental principle of base isolation (BI) is the decoupling of the superstructure from its base.This way the structure fundamental frequency is reduced, and as a result, the earthquake induced forces in the superstructure are significantly mitigated, as it essentially behaves as a rigid body
This paper proposes a Vibration Control System (VCS) that can be used as a supplement to conventional BI techniques and combines the beneficial characteristics of the aforementioned control systems, Tuned Mass Damper (TMD) and QZSs, without their respective drawbacks
Where MN, KN, and CN are the superstructure mass, stiffness and damping matrices, assuming it is mounted on a fixed base, k1 is the lateral stiffness of the first floor, and I is the (N + 3) × 1 influence vector associated with the ground motion Xg
Summary
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