黃泰鈞 橋梁耐震性能評估
Seismic Performance Evaluation of Bridges 摘要 本論文研製之目的在檢視橋梁耐震能力。台灣位處環太平洋地震帶，地震發生頻 繁，結構物的耐震設計因此成為一個相當重要的工作。而屬於結構物之一的橋梁 為交通之命脈，尤其在受到地震等災害時，其在人、物運輸方面扮演著重要的角 色。在當今結構物之耐震設計中，性能設計法已成為重要之設計 理念，其法是以 預先設定的結構性能為目標，使其在設計地震下能達到目標而保有其原本的機 能。 本論文利用結構性能目標來檢視橋梁的耐震能力，以區域性的觀點，採用非線 性靜力分析中的側推法，對一模擬的橋柱及其衍生出來的橋梁進行耐震能力評 估，並根據交通部頒布的「公 路橋梁耐震設計規範」設計出地表加速度，和分析 結果做一比較。結果發現橋柱頂端添加載重的數值越大，其極限剪力越小，譜加 速度也越小。而在模擬橋梁的分析方面，在進行兩個方向的側推分析之後，結果 發現Y 方向彈性段極限剪力較 X 方向為大，且容量曲線的變化情形較 X 方向來得 劇烈，反應譜加速度之值亦較X 方向為大。而在三座不同橋長之橋梁的耐震分析 中，結果發現橋長越長，彈性段極限剪力越小，反應譜加速度之值亦越小。 A procedure is to exam the seismic ability of bridges for the present study. Because of being located at the circum-Pacific seismic belt, earthquakes occur frequently in Taiwan. Therefore, the seismic design of structures has become a very important work. The bridge structure, a kind of the structures, is the lifeblood of transportation, especially plays an important role for the transporting of people and goods while getting the disaster of the earthquake. In the modern seismic design of structures, the performance-based design has become an important concept of design. This method is based on the structural properties of pre-set goal for achieving the goal of seismic design and maintaining their original function.
The objective of the present study is to examine the seismic capacity of the bridge structure. For a regional point of view, it will use a non-linear static method for the pushover analysis to get a simulation of the seismic capacity of the modeling bridge pier and the bridges derived from it. Besides, it will design the ground acceleration according to "The seismic code of highway bridges" promulgated by the Ministry of Communications. Then it will compare the results and the ground acceleration designed. The results will show that the greater value of the load the top of columns get added, the smaller ultimate shear and spectral acceleration it gets. For the
simulation analysis of the bridge, after doing the pushover analysis in both directions, the results will show that the ultimate elastic shear of the Y-direction is larger than
that of the X-direction, the variations of the capacity curve is more severe than that of the X-direction, and the value of the response spectral acceleration is greater than that of the X-direction. For the seismic analysis of three bridges with different lengths, the longer length of the bridge it is, the smaller ultimate elastic shear and spectral acceleration it gets.
