本研究旨在利用向量式有限元素(Vector Form Intrinsic Finite Element)模擬使用不同碰撞模型之橋梁動態反應與不同質量比之含防止落橋裝置隔震橋梁於大地震時之非線性動態反應。過去學者發展多種碰撞模型，包含有線性碰撞力與非線性碰撞力，或增加考慮碰撞時有能量消散情形。依據過去研究顯示，隔震橋梁於大地震中可能產生相當大的位移反應，為避免橋面版發生落橋災害，因此加裝防止落橋裝置。向量式有限元素為一新近發展之結構分析方法，相較於傳統有限元素方法，向量式有限元素對於有大變形、大變位或剛體運動之問題，能以更簡易之運算處理。本研究選用向量式有限元素模擬含防止落橋裝置之動態反應，瞭解橋梁於強震下各構件在考慮有無碰撞效應之破壞順序。 為此，本研究開發新碰撞模型於向量式有限元素法，新碰撞模型包含凱文模型(Kelvin model)、赫茲模型(Hertz model)、赫茲阻尼模型(Hertzdamp model)等，經由算例與有限元素方法(SAP 2000)相較，證實所發展之新碰撞模型之正確性，另外，本研究以兩彈性桿件模擬兩橋面版之碰撞行為，探討各不同碰撞模型在碰撞期間之動態行為與能量損耗之情形；最後以一座兩跨隔震橋梁為目標，進行參數分析探討強震下在不同質量比之隔震橋梁防止落橋裝置與支承、橋墩間之相互影響關係並考慮是否有碰撞情形發生以及極限狀態下之破壞模式。 Isolated bridges have been extensively used to mitigate the induced seismic forces by a shift of natural period. However, the deck displacement becomes excessively large when subjected to a ground motion with large intensity or unexpected characteristics. Such a large displacement may result in unseating of the deck. Therefore, unseating may occur because of pounding effect. This study is aimed to analyze the pounding effect of bridge deck and isolated bridges with or without pounding effect which may exhibit nonlinear dynamic behavior under large earthquake. The Vector Form Intrinsic Finite Element (VFIFE), a new computational method developed by Ting et al. (2004), is adopted in this study because the VFIFE has the superior in managing the engineering problems with material nonlinearity, discontinuity, large deformation and arbitrary rigid body motions of deformable bodies. It is selected to be the analysis method in this study. However, the VFIFE is in its infant stage as compared to the conventional Finite Element. Some kinds of new contact models are herein developed for analyzing the target bridges. Through numerical simulation of examples and comparison with the Finite Element analysis, the developed contact models are verified to be feasible and accurate. Finally, we use many contact model in two elastic rods and analyze an isolated bridge to investigate the extreme functions of the isolators, columns and unseating prevention devices with or without pounding effect and to predict the collapse situation of target bridges.
