摩擦消能隔震系統於簡諧震波作用下之穩定性探討

由摩擦消能隔震系統之等效阻尼比可知，若隔震系統位移越大，其等效阻尼比越低；因此若有一基底振動，在能量不停輸入之情況下，使摩擦消能隔震系統位移隨時間漸增，則等效阻尼比將隨時間漸減；漸減之等效阻尼比又導致往後更大之隔震位移，如此產生惡性循環，終使隔震系統消能不足，產生不穩定之現象。為探討摩擦消能隔震系統穩定性之議題，本文將上部結構視為剛體、隔震系統視為單自由度，以正弦波當作基底加速度，將運動方程式化為無因次，整理出求解流程供工程師參考，並探討設計參數對隔震系統反應指標之影響，供工程師做初步判斷。真實地震雖不會造成摩擦消能隔震系統之不穩定，然而摩擦隔震系統之等效阻尼比隨隔震層位移增加而遞減，使隔震層位移過大，工程師應仔細考量此特徵，增加其安全性。

關鍵字

摩擦消能；簡諧震波；穩定性

並列摘要

According to the equivalent damping ratio formula of frictional isolation systems, the damping ratio becomes lower as the isolation displacement gets larger. Therefore, if the excitation is a simple harmonic wave with constant amplitude and ongoing input energy, then the displacement response of isolation systems will increase with time; on the contrary, the equivalent damping ratio of isolation system will decrease with time. The relationship between isolation displacement and damping ratio will make frictional isolation systems fall into the vicious circle and become dynamic unstable finally. To investigate the issue about dynamic stability of frictional isolation systems, we assumed the super-structure is rigid and the excitation is simple harmonic, and transformed the motion equation of isolation systems into the dimensionless form. We also set the response indices to help practical engineers preliminarily estimate the isolation design. Actually, real ground excitations will not make isolation systems dynamic unstable, but the vicious circle between displacement response and equivalent damping ratio of isolation systems is undoubted. For the reason that we proposed practical engineers take the characteristic into consideration to enhance the safety of isolation design.

並列關鍵字

frictional isolation systems ； simple harmonic waves ； dynamic stability

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摩擦消能隔震系統於簡諧震波作用下之穩定性探討

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