Base isolation system is widely used to protect important and essential buildings from seismic hazards. The use of high damping is effective in reducing the resonance effect under long-period earthquake ground motions. However, high damping increases the acceleration demand under short-period ground motions, leading to a higher risk of damage of nonstructural components. Actually, low damping is beneficial to reduce the acceleration demand under short-period ground motions, suggesting the use of adaptive damping control, that is, high damping under long-period motions and low damping under short-period motions. In order to implement this concept, a semi-actively controlled base isolation system is provided in this article along with a new control law based on the transmissibility theory. Unlike existing studies, the proposed method enables a systematic design procedure for base isolated structures with semi-active dampers, which is called the simplified design procedure in this article. The performance of the proposed system is evaluated with numerical simulations for a base isolated three-story building with magneto-rheological dampers. It was shown that the proposed system achieves a high level of performance under long-period ground motions, while maintaining the exceptional performance of a conventional base isolation system with low damping under short-period ground motions.
Critical Response of Multi-Story Damped Bilinear Hysteretic Shear Building Under Multi Impulse as Representative of Long-Period, Long-Duration Earthquake Ground Motions
