間接式強制振動於橋梁段面順風向與扭轉向氣彈互制效應之識別

Identification of Along-Wind and Torsional-Wind Aeroelasticity for bridge Section Model Using Indirect Forced Vibration Technique

陳玄仁(Hsuan-Jen Chen)

指導教授 ： 吳重成

淡江大學/工學院/土木工程學系碩士班/碩士(2011年)

https://doi.org/10.6846/TKU.2011.00018

摘要

顫振(Flutter)現象為段面結構受風載所產生一種氣彈互制。傳統上，結構顫振導數(Flutter Derivative)之識別採用自由振動方式，但其實驗結果常受周遭試驗環境影響。為改善缺點，本研究使用間接式強制振動的實驗方式。由伺服器的馬達給予振動平台強制振動，透過彈簧擾動段面結構模型，然後量測其在平滑流場下之氣彈戶制效應。
實驗架構為不同寬深比橋面版，其寬深比分為寬深比27、寬深比12.5以及寬深比8。
實驗流程分為非耦合顫振導數與耦合顫振導數識別，主要探討是水平向與扭轉向。均藉由氣彈戶制效應之轉換函數實驗值與理論值比較，在頻率域以曲線擬合最佳化識別出理論是中最佳參數，最後得到橋梁顫振導數。其中理論部分引用狀態空間方程式之觀念進行推導，而最佳化過程則引用基因演算法(Genetic Algorithm)求解，以確保得到最佳解。
本文以三種不同段面模型為例，使用淡江大學土木系風洞實驗室進行上述識別實驗，結果可以得到橋梁段面模型的非耦合顫振導數與耦合顫振導數，其寬深比27實驗結果和Sakar進行比較，以及在耦合項顫振導數識別中改善周泰安在實驗上的誤差，實驗結果寬深比27趨勢接近，而耦合項顫振導數在誤差上有明顯的改善。

關鍵字

橋梁段面 ； 顫振導數 ； 氣動力阻尼 ； 間接式強制振動 ； 氣彈互制 ； 基因演算法

並列摘要

Flutter is one of the aero-elastic behaviors in the wind-induced motion of cross-section structure . Traditionally , the structure of the flutter derivatives (Flutter Derivative) free-vibration mode of identification , but the results often affected by the surrounding test environment . In order to overcome these shortcomings,In this study the use of indirect methods forced vibration test . First , given by the servo motor vibration platform for forced vibration , structural model cross-section through the spring disturbance , and then measured in a smooth flow in each system under the aero-elastic response .
The section model of an air foil and the models with width/depth ratios of 8 、 12.5 、 27 .
The identification scheme proposed is composed of two parts , one is for uncoupled term flutter derivatives and the other is for couple ones . Study is primarily to horizontal and torsional . By comparing the frequency response function of aero-elastic responses with the theoretical values that are derived based on state space equation theory , the optimal parameters involved in the theoretical formula can be determined by using curve-fitting optimization which employs the Genetic Algorithm in the searching process to ensure achieving the global optimum .
In this paper three different cross-section model as an example , the use of Tamkang University’s civil engineering laboratory wind-tunnel experiments the above-mentioned identification results can be non-coupled bridge deck flutter derivatives and coupled flutter derivatives , it’s width/depth ratios 27 of the flutter derivative and Sakar to compare the theory of style , and the coupled term flutter derivatives identified in the improvement of Tai-An Zhou error in the experiment . The results trend close to width/depth ratios 27 , while the coupled terms of flutter derivatives in a significant improvement on the error .

並列關鍵字

Bridge section model ； Flutter Derivatives ； Aerodynamic Damping ； Forced Vibration ； Aeroelasticity ； Genetic Algorithm

參考文獻

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