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Wind and Structures
  Volume 17, Number 3, September 2013 , pages 317-343
DOI: https://doi.org/10.12989/was.2013.17.3.317
 


Yaw wind effect on flutter instability of four typical bridge decks
Le-Dong Zhu, You-Lin Xu, Zhenshan Guo, Guang-Zhao Chang and Xiao Tan

 
Abstract
    When evaluating flutter instability, it is often assumed that incident wind is normal to the longitudinal axis of a bridge and the flutter critical wind speed estimated from this direction is most unfavorable. However, the results obtained in this study via oblique sectional model tests of four typical types of bridge decks show that the lowest flutter critical wind speeds often occur in the yaw wind cases. The four types of bridge decks tested include a flat single-box deck, a flat T-shaped thin-wall deck, a flat twin side-girder deck, and a truss-stiffened deck with and without a narrow central gap. The yaw wind effect could reduce the critical wind speed by about 6%, 2%, 8%, 7%, respectively, for the above four types of decks within a wind inclination angle range between -3 and 3, and the yaw wind angles corresponding tothe minimal critical wind speeds are between 4 and 15. It was also found that the flutter critical wind speed varies in an undulate manner with the increase of yaw angle, and the variation pattern is largely dependent on both deck shape and wind inclination angle. Therefore, the cosine rule based on the mean wind decomposition is generally inapplicable to the estimation of flutter critical wind speed of long-span bridges under skew winds. The unfavorable effect of yaw wind on the flutter instability of long-span bridges should be taken into consideration seriously in the future practice, especially for supper-long span bridges in strong wind regions.
 
Key Words
    long-span bridge; flutter; yaw wind effect; flat single-box deck; flat
 
Address
Le-Dong Zhu : State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China;
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University,Hung Hom, Kowloon, Hong Kong, China;
Key Laboratory of Wind Resistance Technology of Bridges (Shanghai) of Ministry of Transport,Tongji University, Shanghai 200092, China;
Department of Bridge Engineering, Tongji University, Shanghai 200092, China
You-Lin Xu : Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University,Hung Hom, Kowloon, Hong Kong, China
Zhenshan Guo : Key Laboratory of Wind Resistance Technology of Bridges (Shanghai) of Ministry of Transport,
Tongji University, Shanghai 200092, China;
Department of Bridge Engineering, Tongji University, Shanghai 200092, China
Guang-Zhao Chang and Xiao Tan : Lin Tung-Yen and Li Guo-Hao Consultants LTD, Shanghai 200437, China
 

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