| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 98 === 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.
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