變頻式搖擺支承於近域隔震之運用

Rocking Bearings with Variable Frequency for Near-Fault Seismic Isolation

盧煉元(Lyan-Ywan Lu) ； 李姿瑩(Tzu-Ying Lee) ； 葉奕麟(I-Ling Yeh) ； 張洵(Hsun Chang)

《中國土木水利工程學刊》 22卷3期 (2010/09) Pp. 283-298

https://doi.org/10.6652/JoCICHE.201009_22(3).0005

摘要

近斷層震波一般均含有長週期脈衝成份，易造成傳統隔震結構基底位移過大之問題。為改善此一現象，本文提出一變頻式搖擺隔震支承（簡稱PRB）之構想。經由理論之推導可知，該支承之水平回復勁度為支承位移之函數，故具變頻隔震之功效。且其隔震頻率僅受支承幾何參數之控制，與結構自重無關。當支承搖擺面函數以六次方多項式加以定義時，則PRB支承之回復力具有一軟化段與硬化段，可分別用以抑制隔震結構之結構加速度與基底位移反應。本文數值模擬結果顯示，由於變頻之特性，PRB隔震結構對於低頻地震力確可減緩共振現象之發生。對於近域脈衝波所引致之支承位移過大現象，具有極佳的防制效果。且對上部結構之加速度反應亦具良好之減震效果。

關鍵字

隔震技術 ； 變頻隔震 ； 搖擺支承 ； 近斷層震波 ； 可變勁度

並列摘要

A near-fault earthquake usually possesses a long-period pulse-like waveform that can result in an excessive isolator displacement in a conventional isolation system. To alleviate this problem, a rocking bearing with a variable frequency, called polynomial rocking bearing (PRB), is proposed in this study. Because the isolation stiffness of the PRB is a function of the isolator displacement, so the isolation frequency of a PRB isolator becomes variable. In addition, the isolation frequency is merely determined by the geometric parameters, and is independent of the isolated structural weight. When the rocking surface of the PRB is defined by a six-order polynomial function, the restoring force of a PRB bearing will have a softening behavior followed by a hardening behavior, which aims to suppress the maximum responses of the structural acceleration and isolator displacement. The result of numerical simulation has demonstrated that due to the property of variable frequency, the proposed bearing is able to effectively mitigate the resonance effect due to a low-frequency excitation. The result also shows that the PRB is particularly effective in suppressing the isolator displacement induced by a near-fault earthquake with a long-period pulse.

並列關鍵字

seismic isolation ； variable isolation frequency ； rocking bearing ； near-fault earthquake ； variable stiffness