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Wind and Structures
  Volume 7, Number 6, November 2004, pages 421-447
DOI: http://dx.doi.org/10.12989/was.2004.7.6.421
 


Time domain buffeting analysis of long suspension bridges under skew winds
G. Liu, Y. L. Xu and L. D. Zhu

 
Abstract
    This paper presents a time domain approach for predicting buffeting response of long suspension bridges under skew winds. The buffeting forces on an oblique strip of the bridge deck in the mean wind direction are derived in terms of aerodynamic coefficients measured under skew winds and equivalent fluctuating wind velocities with aerodynamic impulse functions included. The time histories of equivalent fluctuating wind velocities and then buffeting forces along the bridge deck are simulated using the spectral representation method based on the Gaussian distribution assumption. The self-excited forces on an oblique strip of the bridge deck are represented by the convolution integrals involving aerodynamic impulse functions and structural motions. The aerodynamic impulse functions of self-excited forces are derived from experimentally measured flutter derivatives under skew winds using rational function approximations. The governing equation of motion of a long suspension bridge under skew winds is established using the finite element method and solved using the Newmark numerical method. The proposed time domain approach is finally applied to the Tsing Ma suspension bridge in Hong Kong. The computed buffeting responses of the bridge under skew winds during Typhoon Sam are compared with those obtained from the frequency domain approach and the field measurement. The comparisons are found satisfactory for the bridge response in the main span.
 
Key Words
    long suspension bridge; skew winds; buffeting response; time domain; equivalent turbulent wind velocity; field measurement; Typhoon Sam; comparison.
 
Address
G. Liu and Y. L. Xu; Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, ChinarnL. D. Zhu; State Key Laboratory for Disaster Reduction in Civil Engineering and Department of Bridge Engineering, Tongji University, Shanghai 200092, China
 

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