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Wind and Structures
  Volume 22, Number 3, March 2016 , pages 273-290
DOI: https://doi.org/10.12989/was.2016.22.3.273
 


Insight into coupled forced vibration method to identify bridge flutter derivatives
Fuyou Xu, Xuyong Ying and Zhe Zhang

 
Abstract
    The flutter derivatives of bridge decks can be efficiently identified using the experimentally and/or numerically coupled forced vibration method. This paper addresses the issue of inherent requirement for adopting different frequencies of three modes in this method. The aerostatic force components and the inertia of force and moment are mathematically proved to exert no influence on identification results if the signal length (t) is integer (n=1,2,3...) times of the least common multiple (T) of three modal periods. It is one important contribution to flutter derivatives identification theory and engineering practice in this study. Therefore, it is unnecessary to worry about the determination accuracy of aerostatic force and inertia of force and moment. The influences of signal length, amplitude, and frequency ratio on flutter derivative are thoroughly investigated using a bridge example. If the signal length t is too short, the extraction results may be completely wrong, and particular attention should be paid to this issue. The signal length (N>5) is strongly recommended for improving parameter identification accuracy. The proposed viewpoints and conclusions are of great significance for better understanding the essences of flutter derivative identification through coupled forced vibration method.
 
Key Words
    bridge; flutter derivative; forced vibration method; multiple-degree-of-freedom coupling; theoretical proof; exemplification
 
Address
Fuyou Xu, Xuyong Ying and Zhe Zhang: School of Civil Engineering, Dalian University of Technology, Dalian 116024, China
 

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