- 學位論文
橋樑防落拉桿之實驗與力學分析
The Experiment and Analysis of Restrainers for Bridges
摘要
落橋是影響程度相當嚴重的橋梁震災，加設防落裝置可以有效降低落橋發生的機率，也是防止落橋最經濟與最有效之方法。國內防落裝置之使用量於近年已有大幅的提昇，但卻無較完整的設計訪法與規範。我國目前常使用的防落裝置種類不多，大致上有止震塊、防落拉桿、剪力榫、剪力鋼箱及支承抗拉拔裝置等，又防震拉桿有鋼索和鋼棒二種形式，鋼索多用於鋼橋防落，而鋼棒則應用在RC橋梁，本研究針對鋼棒型式之防落拉桿進行探討。 日本已有完善之落橋防制系統流程，而美國防落裝置大致上僅有防震拉桿和鋼索兩種型式，美國在橋梁設計的理念偏向於設計足夠的防落長度，即不需防落裝置。相較之下，我國和美國的防落裝置都不如日本嚴謹，因此新設計的橋梁多無防落裝置，而防落裝置則多用於舊橋補強。日本與我國的橋型相似，但是我國許多設計卻採用美國AASHTO的設計，所以本計畫將融合美國和日本的設計經驗，進而發展適合我國的設計規範。 本研究計劃首先蒐集、彙整國內外防落拉桿與裝置等資料，配合橋梁功能性支承系統耐震性能設計與補強方法之研究，著手進行相關實驗，並採用ANSYS分析軟體進行分析探討，以實驗成果與理論分析相互驗證之結果，進而提出一簡易的防落拉桿設計方法與結合其他設施之整座橋梁分析方法，確保防震拉桿可以發揮功效，使橋梁上部結構在大地震時不發生落橋的行為與震後可快速修復等功能，提供國內顧問公司與施工廠商作為遵循之依據。
並列摘要
There have been many examples of bridge failure caused by relative movement of spans in the longitudinal or the transverse directions exceeding the seating widths, and resulting in unseating at unrestrained movement joints in Northridge Earthquake (1994, U.S.A.), Kobi Earthquake (1995, Japan) and Ji Ji Earthquake (1999, Taiwan). This has been a particular problem for simply supported span bridges with tall columns. Restrainers may be placed across the joint in an attempt to reduce the relative displacements, or the displacement capacity of the movement joint can be increased. Restrainers are used to restrain displacement between the expansion joint, restrainers may be placed in order that longitudinal seismic force can be transferred between adjacent frames. The analysis and design for the interaction of inelastic frames connected by restrainers are complex and cannot be achieved by simple elastic analyses. Results from dynamic inelastic analysis incorporating relatively sophisticated modeling of the movement joints indicate that maximum longitudinal displacements can be estimated. Determination of the appropriate strength for the restrainers and reduction in displacement caused by stiff restrainers are difficult unless dynamic inelastic analyses are carried out. In many bridges the appropriate treatment for movement joints will be to use restrainers to lock the movement joints so that essentially no relative movement can occur. In Japan, the design of restrainers and other earthquake resistance devices have been very well developed. In the States, the restrainers are mostly used in the existing bridges which are seismic deficiency. In Taiwan, the seismic design code of bridge follows the AASHTO bridge desingn code, and some of the earthquake devices and restrainers are supported by Japan. Therefore, we wuld like to developed the design and analysis methodology or guideline of the restrainers for the usage in Taiwan. The ANSYS finite-element softwares will be used in this project to simulate the force in the restrainer under earthquakes.