應用晃動式隔震系統於近斷層結構防震設計之研究

Abstract

本研究主要是探討應用晃動式隔震系統於近斷層結構防震設計之可行性。晃動隔震系統是藉由結構物基層與基礎間之不連續介面，使結構物在傾倒彎矩大於自重所造成之抵抗彎矩時，產生晃動而釋放柱基的抗彎力矩，進而截斷地震力之傳輸，防止柱因地震反應過大而產生降伏。文中除了進行晃動隔震結構之理論推導外，並利用四階的朗吉-卡特法建立非線性動力分析程序。數值分析結果顯示，晃動隔震系統之穩定性相依於近斷層擾動脈衝之延時與振幅。增設液態黏滯阻尼器有助於提升晃動隔震系統於近斷層之穩定性與有效減緩其動力反應。晃動機制配合消能元件作為防止傾倒措施，已被證實為一種可行且有效的隔震系統。

In this study, the feasibility of utilizing rocking-type isolation systems for near-fault earthquake protection of structures is explored. With a discontinuous interface between the base and the underlying foundation, the rocking system is allowed to rock intermittently as the seismic overturning moment exceeds the restoring moment contributed by gravity. The rocking isolation then releases the resisting overturning moment while counteracts the earthquake load with the rotational inertia with respect to the supporting base, thus preventing the columns from yielding. Analytical modeling of this nonlinear dynamic system is derived and a numerical procedure developed based on the fourth-order Runge-Kutta-Nyström method. It is shown that the stability of rocking isolation depends on the pulse duration and amplitude of the near-fault earthquake via numerical simulations. It has been confirmed that stability and effectiveness in dynamic response alleviation of the rocking type isolation systems under near-fault earthquakes can be enhanced by the introduction of viscous fluid damper. The rocking mechanism integrated with energy dissipative dampers for up-lift control has been demonstrated to be a feasible and promising alternative of seismic isolation.