過去研究已證實滑動隔震支承，如摩擦單擺支承 (Friction Pendulum System, FPS) ，可降低地震危害度，且已廣泛應用於結構物。然而，含FPS之結構物於近斷層地震中之減震效果不如預期，此乃隔震後之結構週期與地震之主要振動週相近，產生共振效應。為改善近斷層地震下之隔震橋梁動力反應，本研究採用多項式滾動支承 (Polynomial Rocking Bearing, PRB)作為隔震裝置。PRB由球窩圓頭、球窩基座與滾動曲面組成，且滾動曲面為六次多項式構成，因此支承勁度可隨位移變化，達到調整隔震週期之目的。 前人研究已證實PRB應用於等高橋梁或建築結構，在近斷層地震作用時具有良好之隔震效果，但PRB目前尚未應用於不等高橋墩橋梁，本研究目標為應用PRB於不等高橋墩之實際橋梁，且使用PSO-SA (Particle Swarm Optimization-Simulated Annealing) 混合式搜尋法求得PRB之最佳化參數。最後再與傳統FPS比較，證實不論近域或遠域地震，PRB皆能更有效地降低橋面板位移。 ;Conventional sliding isolators such as Friction Pendulum System (FPS) are widely used and effectively proved to mitigate seismic hazard in far-fault earthquakes. However, it may not be effective when the structures are subjected to near-fault earthquakes because the earthquake’s period is usually close to the isolation period. In this study a Polynomial Rocking Bearing (PRB) which has variable isolation stiffness is used to improve the performance of seismic isolation systems under near-fault earthquakes. A PRB is composed of an articular joint and concave rocking surface. The rocking surface is defined by a sixth-order polynomial function. According to previous studies, the PRB has been verified to effectively suppress the large isolator displacement induced by near-fault earthquakes on building and regular bridges. However it has not been used yet in the irregular bridges. This study aims to analyze the behavior of Polynomial Rocking Bearing installed on an irregular bridge. Also the optimal design parameters of PRBs are found out by using the Particle Swarm Optimization-Simulated Annealing (PSO-SA) hybrid searching algorithm. As compared with conventional Friction Pendulum Systems (FPS), the performance of PRBs is superior to effectively suppress the displacement of the bridge deck in both near and far-fault earthquakes.
