FPS隔震儲存槽之試驗與分析

Abstract

台灣位處環太平洋地震帶，對於石化儲存槽的耐震能力與安全檢核工作十分重要。世界各國的油槽遭受地震侵襲而受到嚴重損壞例子屢見不鮮，九二一集集地震國內亦有油槽遭受到嚴重損壞。歷經九二一集集地震侵襲後，吾人更應記取教訓，對於石化儲存槽之耐震設計標準勢必更為嚴苛。本文完成剛性隔震儲存槽之振動台試驗，確認摩擦單擺隔震支承於儲存槽防震應用之可行性，並驗證理論分析模式之合理性。本研究製作了直徑 1.36m，高2 m，容量3噸之儲存槽模型，利用交通大學土木系自行研發的地震模擬振動台進行一系列試驗，包括以El Centro、Hachinohe及Kobe等地震歷時資料為輸入震波，並調整不同之PGA強度進行測試，以探討地震頻率內函及地震強度對儲存槽隔震效益的影響。此外，在槽殼半徑(R)固定的情況下，考慮不同水位高度(H)進行試驗，以探討高徑比(H/R)對隔震效益之影響。試驗結果顯示，在各種地震下摩擦單擺支承對儲存槽均有減震效果，且地震強度愈大時減震效益愈明顯；而水位愈高時，減震效果也愈佳。此外，考慮剛性儲存槽之數值模擬分析與試驗結果有相當程度之契合，顯示本文所提理論分析模式能夠準確預測儲槽及流體在地震下之動力行為

Storage tanks are vulnerable to earthquakes, as demonstrated recently in Chi-Chi earthquake (1999) of Taiwan, and numerous other major earthquakes worldwide. Development of cost-effective earthquake-resistant design and retrofit techniques for industrial tanks is imperative in Taiwan, as the seismic design standard has been significantly enhanced in the post-Chi-Chi revision. In this study, a series of shaking table tests has been conducted to assess the feasibility of seismic base isolation for liquid-filled storage tanks experimentally. The friction pendulum bearings (FPS) are considered rather than the elastomeric bearings as the dynamic characteristics of an FPS-isolated tank remain unchanged regardless of the storage level. Experimental results show evident reductions in dynamic pressure on the shell wall of the tank consistently while isolated. Effectiveness of FPS for seismic isolation of storage tanks is confirmed. Moreover, numerical simulations carried out using a hybrid structural-hydrodynamic model previously devised agree well with the test results, indicating adequacy of the analytical model