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  • 學位論文

考慮施工步驟之斜張橋最佳化設計

Optimal Design of Cable-Stayed Bridge Based on Construction Stage Analysis

指導教授 : 呂良正

摘要


在現代橋梁設計中,斜張橋作為當今中長跨度橋梁中最為常用的橋型之一,其輕盈的美學效果以及高經濟性受到建築師和工程師的一致認同。斜張橋可供選擇變化的設計參數眾多,設計者能對鋼索預力大小、橋塔高度、橋塔傾斜角度、鋼索錨碇位置、鋼索數目等,進行單層或多層最佳化設計,但通常此類設計僅對於完工後的狀態做最佳化,並未對於斜張橋的施工階段做分析、檢核乃至於最佳化設計,忽略了在施工過程中可能出現的過大桿件應力與結點位移,且由於其鋼索系統的高度靜不定以及大跨度的梁結構,更易造成結構破壞或位移過大導致施工性不足的問題。因此對於斜張橋在施工階段的設計與分析,是整個橋梁工程中重要的一環。 本文從結構最佳化及演算法開始談起,介紹斜張橋最佳化中的重要參數及適用之演算法,接著提到斜張橋主要結構組成,不同施工工法的優缺點,以及鋼索的型式和安裝步驟。 在對施工工法及步驟有深入了解後,便可利用結構分析軟體SAP2000進行斜張橋施工階段分析,本文將施工分為兩個重要階段,分別為新節塊施作階段和鋼索預力施加階段,鋼索預力又搭配正裝分析和倒裝分析兩種不同的分析方法做鋼索預力最佳化,加上工作車及橋塔輔助索之應用,充分模擬一座斜張橋在施工過程中可能出現的較大桿件應力,並藉由不同的最佳化方法進行鋼索預力之最佳化,最後將各階段之成果輸出,進行規範檢核,完成考慮施工階段之斜張橋最佳化設計。 最後以一單塔不對稱斜張橋做實例分析,以正裝分析和倒裝分析兩種施工階段分析方法進行鋼索預力之最佳化,並把所有方法之結果輸出,比較各自優缺點,檢討規範檢核結果,對此單塔不對稱斜張橋做設計與施工之建議。 斜張橋之設計與施工是一項複雜的工作,本研究透過施工過程模擬及最佳化技術解決斜張橋施工過程中的一部份問題,為工程師及施工單位提供一些設計及施工準則。

並列摘要


The cable-stayed bridge is one of the most popular bridges types chosen by architects and structure engineers in modern bridge design because of its aesthetic appeal and economy. When designing cable-stayed bridge, lots of design variables such as cable force, pylon height, number of cables need to be decided. However, the design for these varibles usually focus on the completion stage of cable-stayed bridge but not construction stage, it might ignore the overvalue of stress ratio and joint displacements between the construction stage. In addition, as cable-stayed bridges are highly undetermined with severe nonlinearity, it might appear element damage and lack of constructability between construction stage easily. So it’s important to consider the design and analysis about the construction stage. The research start with structure optimization, algorithm and important variables of cable-stayed bridge. Then focus on the pros and cons between different construction methods, and introduce the types and installation method about the stay cables. After knowing the construction method and sequence, we can use SAP2000 to do the analysis about construction stage. The research divides the construction stage into two parts. One is new girder construction part, the other is cable stays installation part. The second part will use two different analysis method, Forward Analysis and Backward Analysis, to do the optimization of cable force. Moreover, we will put auxiliary stays about travelers and pylons into the construction stage analysis, and output the results and check with specifications. Finally, we finish the optimal design of cable-stayed bridge based on construction stage analysis. The research give an example of single pylon cable-stayed bridge in the last chapter. We use two construction analysis method, Forward Analysis and Backward Analysis, to do the optimization of cable force, and show the results of different methods in figures. We discuss the pros and cons about different methods and give some advises in design and construction of cable-stayed bridge. Design and construction of cable-stayed bridge is a tough task. The research is aimed at solving some specific problems of cable-stayed bridges and provide engineers some advises for cable-stayed bridge in design and construction.

參考文獻


詹洵(2015),結合結構分析軟體與最佳化設計軟體之斜張橋設計,國立臺灣大學土木工程學研究所碩士論文。
柯俊宇(2014),結構最佳化軟體開發:應用於斜張橋設計,國立臺灣大學土木工程學研究所碩士論文。
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