曲線橋梁之等值靜力風載重

Equivalent Static Wind Loads of Curved Bridges

林焯斌(Cheuk-Pan Lam)

指導教授 ： 林堉溢

淡江大學/工學院/土木工程學系碩士班/碩士(2019年)

https://doi.org/10.6846/TKU.2019.00686

摘要

隨著橋梁工程技術的進步，橋梁漸趨狹長，受風反應越來越明顯，因此風洞試驗受到重視，但風洞試驗在進行試驗時，消耗時間大，成本也高，計算過程涉及到風洞試驗和隨機振動分析等複雜過程，不容易為工程設計人員掌握，因此需要更簡便使用的橋梁結構抗風設計方法，等值靜力風載重就是以這一背景下提出。目前最常用以求得等值靜力風載重的方法為LRC法及慣性力分佈，假設振態間互相獨立，並且分別計算出背景反應及共振反應再加以組合，此計算過程非常繁複，並且在複雜結構上可能會有誤差，因此研究主要以在考慮抖振效應，並且在不分開背景反應及共振反應下，考慮振態之間的耦合性，產生等值靜力風載重便是本文之重點。
本論文以數值分析為主，研究內容分為三個部份，第一部份以簡支梁確立理論，並且與背景加共振之做法作出比較，檢視計算結果的差異。第二部份以曲橋為例子，為橋增加曲度使振態更耦合，檢視本文方法使用在耦合性高的橋梁之計算結果。第三部份為S形橋，再進一步增加橋振態的複雜性，與背景加共振之做法比較出與本文方法的差異性。
在氣動耦合不明顯的結構下，以各種方法都會得準確的估算，但以載重分佈來說，以本文方法的結果最具有合理性。在振態耦合度較高的結構上
，本文方法與抖振分析結果誤差最小，特別在扭轉方向及反應為四分之一跨的時侯。

關鍵字

橋梁 ； 等值靜力 ； LRC ； 慣性力分佈 ； 曲橋 ； 抖振

並列摘要

Duo to the improvement of bridge engineering technology, the bridge span is getting longer and the wind response is more significant. Therefore, the wind tunnel experiments of long-span bridges have become more important. But the time consuming and the high costing are the weak points of wind tunnel experiments. And The calculation process involves complicated processes such as wind tunnel test and random vibration analysis, which is not easy for the engineers to use. Therefore, it is necessary to use the wind-resistant design method of the bridge structure which is easier to use, and the equivalent static wind load is proposed in this context. At present, the most commonly used method for obtaining the equivalent static wind load is the LRC method and the inertial force distribution. It is assumed that the modes of structure are independent of each other, and the background reaction and the resonance reaction are respectively calculated and combined. This calculation process is very complicated and there may be deviation in the complex structure. Therefore, the equivalent static wind loads in this study mainly considers the mode and aerodynamic coupling between the vibration modes without separating the background responses and the resonance responses.
This study is based on numerical analysis. The research content is divided into three parts. The first part establishes the theory with simple support beam and compares it with the background plus resonance method to examine the difference of calculation results. The second part takes the curved bridge as an example. The curvature is added to the bridge to make the modal shape more coupled. The method of this method is used to calculate the bridge with significant coupling. The third part is the S-shaped bridge, which further increases the complexity of the bridge modal shape. The differences between this method of the results and the background and resonant method are discussed.
For structures with minor aerodynamic coupling, the results can be accurately estimated by various methods, but the load distribution of this method of this study is the most reasonable. For structures with high aerodynamic coupling, the error of the method of this study compared to the traditional buffeting analysis is the minimum, especially in the torsional direction and at the quarter span.

並列關鍵字

Bridge ； LRC ； Equivalent Static Wind Load ； Buffeting ； Curved Bridges

參考文獻

參考文獻

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