著者

谷地畝 和夫 鈴木 彰 齋藤 雄太 得能 将紀 小林 正人

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.86, no.781, pp.381-391, 2021 (Released:2021-03-30)

参考文献数

17

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In recent years, there is concern about the occurrence of extreme ground motions that greatly exceed the amplitude levels and durations expected in conventional design level. Therefore, seismically isolated buildings are required to secure the seismic isolation performance for small earthquakes and to suppress the excessive displacement of the seismic isolation layer for extreme ground motions. As one of the effective means to meet the above requirements, in addition to an electromagnetic switching semi-active seismic isolation system, a cheaper and more reliable passive damper is being developed. Meanwhile, the authors have proposed a dead zone mechanism that is an accessory device connected to the existing oil damper. When the relative displacement of seismic isolation layer is smaller than the set amplitude (medium and small earthquakes level), the dead zone mechanism only slides and no damping force is generated in the oil damper, and when the amplitude is larger than the set amplitude (extreme ground motions), this mechanism generates damping force and suppresses excessive displacement. Furthermore, one of the features of this mechanism is that it has a mechanism that automatically returns the rod to the original position after the earthquake. In this paper, we analyze the seismic response of seismically isolated buildings using the dead zone mechanism to understand the response characteristics.  1) When the publicly announced wave and pulse ground motions are used as input earthquakes, an oil damper with a dead zone mechanism is used in the seismic isolation building to ensure seismic isolation performance for small and medium earthquakes, while suppressing excessive displacement of the seismic isolation layer for extreme ground motions. It was confirmed that the desires effect of doing was obtained. In this analysis case, the most effective performance was shown when the dead zone width was set to 15cm. 2) When the long period ground motions is used as the input ground motions, the acceleration response of the GAP model is larger than that of the OD model, but the acceleration is small at about 100~200cm/s2, which is considered to be within the allowable range for seismic isolation. 3) It was confirmed that the automatic return spring in the dead zone mechanism automatically returns the rod in the mechanism to the neutral position at the end of the earthquake. Therefore, by automatically returning the dead zone mechanism to the automatic return spring in the dead zone mechanism, it is possible to maintain the structural performance assumed at the time of design even when multiple earthquakes occur in a short period of time. 4) In all earthquakes, when the seismic isolation layer displacement reaches the dead zone width, the absolute acceleration increase in the lower layer. The cause is considered to be a reaction force due to the elements of the dead zone mechanism contacting each other. The 1/3 octave band analysis was applied to the time history waveform of the absolute response acceleration above the seismic isolation layer of each model. It was confirmed that the value was sufficiently smaller than the judgment value of the rank with the lowest anxiety level, compared with the evaluation curve in the anxiety level evaluation by Takahashi et al. Therefore, it was confirmed that the increase in acceleration response when the elements in the dead zone mechanism were in contact had little effect on the habitability.

著者

谷地畝 和夫 稲井 慎介 山本 健史 得能 将紀 小林 正人

出版者

一般社団法人 日本建築学会

雑誌

日本建築学会技術報告集 (ISSN:13419463)

巻号頁・発行日

vol.27, no.65, pp.136-141, 2021-02-20 (Released:2021-02-20)

参考文献数

10

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The seismic isolation structure has a habitability problem that it tends to be vibrated when it is always used. Therefore, we have newly developed a seismic isolation device that controls vibration in the infinitesimal range. The seismic isolation device is an elastic slide bearing and an oil damper integrated, and the performance of the damper in the infinitesimal vibration range was confirmed by vibration tests. We confirmed the effect of adopting it in a building by analysis. We also conducted dynamic tests to verify the performance of the seismic isolation device and put it into practical use.