2025 Volume 25 Issue 2 Pages 2_143-2_154
The experience of recent massive earthquakes and the damage they have caused have prompted conceptual studies for realizing resilient cities in order to achieve a higher level of safety. While levitation systems have been developed for horizontal seismic isolation that can provide high performance, improvements are needed for vertical seismic isolation. Although many performance verification tests have been conducted in the development of vertical seismic isolation systems, few studies have quantitatively demonstrated the required performance. This paper analyzes the seismic response of levitation base isolation systems based on the characteristics of observed vertical seismic motions, clarifies the required performance of vertical base isolation, quantitatively shows the effects of weight eccentricity and tower ratio on the response, and proposes a threshold value where the response increase is negligible. It also clarifies the tendency for the rocking response to become smaller with horizontal long periodization.
