非線形挙動を有する上下振動の振動低減装置の解析

抄録

Earthquake countermeasures are necessary in Japan, because earthquakes frequently occur. Among the earthquake countermeasures, seismic isolator is attracting attention. Seismic isolator is the device to absorb earthquake vibrations between the ground and the structure. Currently, seismic isolation devices are becoming widespread. However, most of them are only effective against horizontal vibrations and do not adequately protect against vertical vibrations. In recent years, Tokyo inland earthquake which accompanied by violent vertical vibrations is predicted. Therefore, it is necessary to develop a vibration reduction device which can absorb vertical vibrations. A vibration reduction device with nonlinear behavior was developed in the past. According to experiment results, its device was able to reduce the maximum amplitude ratio to about 1.3. However, the resonance occurred in the low frequency range from 4 to 5Hz. In this study, the behavior of a vibration reduction device with nonlinear behavior on vertical vibrations was analyzed in order to reduce the resonance to below 1Hz while suppressing the amplitude ratio. In the analysis, two types of spring constants of the experimental device and the friction coefficient of the bearings attached to the experimental device were adjusted. The analysis results showed that if the friction coefficient of the bearings could be reduced, the resonance of the experimental device could be reduced.