| 講演要旨(和文) | | 強風の中で敢行された青森青隆寺五重塔の耐震性に関する振動実験の結果をまめると以下のようになる. １）五重塔の基本振動数は 1.1Hz であり減衰定数 ｈ＝0.36の大きな値を持つ. ２）塔は初重階では5個の卓越振動で振動する.それは ３重階で2個に減衰する. ３）5重階では基本振動数1.1Hzの振動のみとなる. ４）高次振動数によるスネーク・ダンス振動は見られ ない. ５5重階の上部で吊り下げられた重い心柱は約6秒の 振り子となり,塔本体の横方向からの力に対抗して 姿勢の安定化に大きな役割をしている. ６）重い心柱は付加質量機構として塔の制振作用に 寄与 していると考えられる. , |
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| | 講演要旨(英文) | | We have examined the vibration characteristics of five-storied timber pagodai. in regards with earthquake-resistant capacity. The natural frequency, damping constant and maximum amplitude ratio for the pagoda have been determined on the 1st stage,3rd stage and 5th stage floor. The results obtained have shown that the pagoda has fundamental vibration frequency of 1.1 Hz and large damping constant h of 0.36. The shimbashira( central core-pillar) works as earthquake motion regulation mechanism with appended mass. The 1st.stage floor have five predominant vibrations of different frequencies,such as 1.1Hz, 2.6Hz,4.8Hz,and 6.2Hz.However high frequency components of vibrations are decayed on the upper parts of the pagoda. The result shows that the timber pagoda has very highly efficient absorption mechanism of vibration energy due to Coulomb friction. |
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