防止落橋裝置為避免橋梁上部結構於大地震中崩落，造成人員傷亡、財產損失的最後一道防線，其重要性不亞於橋梁其它耐震構件，如橋墩、支承等。921 大地震及日本阪神大地震中，為數不少的橋梁係因落橋而造成重大損傷，然而防落裝置卻始終被視為橋梁的”附屬設施”，且橋梁耐震設計規範中，也僅就防落裝置之設計強度做簡單地規定，目前世界各國耐震設計之理念均朝向性能設計發展，了解防落裝置於極限狀態下之性能有助於訂定性能目標。防落裝置必與支承相提並論，且其於強震中之動力反應必與支承、橋墩產生互制影響，本計畫將針對國內最常使用之剛性支承橋梁與未來趨勢之隔震支承橋梁有系統地探討其設置各類型防落裝置之耐震性能，分析方法將採新近發展之向量式有限元素法，因其具有分析大變形、大變位與結構崩塌等動力問題之優點。此外，目前防落裝置並未具有消散能量之功能，本研究擬利用過去半主動結構控制之研究成果，將半主動結構控制系統導入防止落橋裝置中，首先，必須解決現有實際運用時之問題點，再結合半主動結構控制與傳統防止落橋裝置之功能開發混合型防落裝置，中小地震時，它可提供控制與消散能量功能，大地震時，瀕臨極限破壞階段再提供防落功能，特別對於設置空間受限之橋梁，此單一裝置即可同時達到減震與防落之目的。Unseating prevention devices act as fail-safe to prevent falling of bridge decks, which may cause casualty and loss of property, under an extreme earthquake. Unseating prevention devices play the same important role as piers and bearings in seismic design of bridges. There are dozens of casualty and loss due to unseating of bridge decks during Chi-Chi earthquake and Japan Kobe earthquake. However, unseating prevention devices are generally regarded as accessories as compared to piers and bearings, and there are only simple regulations, such as design strength, in the current bridge seismic design codes. Lately, it is expected to modify the bridge seismic design codes based on the seismic performance of whole bridges and their elements. Understanding of the performance of unseating prevention devices under extreme condition is helpful to determine the goal of performance. Whenever the unseating prevention devices are considered, the bearings should be taken into account and the interaction among unseating prevention devices, bearings and piers should be taken into account as well. This study will systematically investigate the seismic performance of different unseating prevention devices for the bridges with rigid bearing system and isolated bearing system. Vector Form Intrinsic Finite Element (VFIFE) method will be adopted to analyze the extreme situation of the studied structures because VFIFE method is superior in dealing with dynamic problems having large displacement and fracture. Additionally, the existing types of unseating prevention devices are not capable of dissipating energy. We will try to introduce the semi-active structural control system into the unseating prevention devices based on the research result of structural control system in the past. At first, it is needed to solve the problems when the structural control system is implemented. Then we will try to develop a hybrid unseating prevention device which combines the functions of semi-active control and traditional unseating prevention device. During small to moderate earthquakes, the new device is capable of dissipating energy and controlling the seismic response. During extreme events, it can avoid the occurrence of unseating of bridge decks. 研究期間 : 9808 ~ 9907
