橋梁地震時大梁間與伸縮裝置留設適當間隙之研究

Abstract

本文主要在探討不同橋梁振動單元，在同一地震作用下，由於週期不盡相同，所產生的相對位移。利用三組與規範反應譜相符地震歷時進行非線性動力歷時分析，並以此結果與橋梁耐震設計規範草案中之靜力分析法所計算的相對位移做比較，所使用的變數包括週期的差異、不同地區的設計地震、中度地震加速度係數。橋梁上部結構使用單質點來簡化模擬分析，橋梁下部的單柱樁基礎模擬，分別使用SAP2000中不同的線性與非線性元素。 在實例分析中，由於上部結構重量遠大於下部結構，所以真實橋樑和單自由度質點對相對位移的影響不大，便以單自由度質點來簡化分析，以自然週期為變數進行分析，討論兩個不同週期的振動單元對於相對位移的影響。 接著再以不同地區的地震加速度係數為變數，分析在不同地區時對於相對位移的影響，並簡化相對位移與耐震規範靜力分析法所計算得出長週期者的容許側位移，使用調整係數C來表示其關係。亦以超過上部結構相對位移為原則其提出一套簡易的估算公式，以供工程師使用。最後探討該估算公式與單自由度質點相對位移比較的精確性。

The purpose of this thesis was to study relative displacements of different bridges under earthquakes because the different bridges have different period. In this study, three earthquake time histories corresponding to the design spectrum were applied to nonlinear dynamic time history analysis of the model. The dynamic results were compared with the result of static analysis. The parameters used of the dynamic analysis and static analysis include period of model, the coefficient of corresponding to the design spectrum. The top structure of the bridge uses the single particle to simplify simulation to analyse, the substructure of the bridge uses the spring to simplify simulation to analyse. In the analysis, the weight of top structure is more than the substructure, So real bridge and single degree of freedom’s affect not heavy for the relative displacement. Accordingly, the analysis by the single degree of freedom model and the parameters used of the analysis are period, to discuss the influence of two vibrant models in the different periods for the relative displacement. Then regard different coefficients of seismic acceleration of in different areas, analyse the influence on relative displacement when different in the area, and simplify the relation between relative displacement and single degree of freedom displacement to coefficient C for the engineer to use.