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Structural Engineering and Mechanics
  Volume 82, Number 4, May25 2022 , pages 517-542
DOI: https://doi.org/10.12989/sem.2022.82.4.517
 


Numerical investigations on the effect of mean incident wind on flutter onset of bridge deck sections
M. Keerthana and P. Harikrishna

 
Abstract
    The effect of mean angle of wind attack on the flutter critical wind speed of two generic bridge deck cross-sections, viz, one closed box type streamlined section (deck-1) and closed box trapezoidal bluff type section with extended flanges/overhangs (deck-2) type of section have been studied using Computational Fluid Dynamics (CFD) based forced vibration simulation method. Owing to the importance of the effect of the amplitude of forcing oscillation on the flutter onset, its effect on the flutter derivatives and flutter onset have been studied, especially at non-zero mean angles of wind attack. The flutter derivatives obtained have been used to evaluate flutter critical wind speeds and flutter index of the deck sections at non-zero mean angles of wind attack studied and the same have been validated with those based on experimental results reported in literature. The value of amplitude of forcing oscillation in torsional degree of freedom for CFD based simulations is suggested to be in the range of 0.5o to 2o, especially for bluff bridge deck sections. Early onset of flutter from numerical simulations, thereby conservative estimate of occurrence of instability has been observed from numerical simulations in case of bluff bridge deck section. The study aids in gaining confidence and the extent of applicability of CFD during early stages of bridge design, especially towards carrying out studies on mean incident wind effects.
 
Key Words
    angle of wind attack; bridge deck section; Computational Fluid Dynamics (CFD); flutter critical wind speed; flutter derivatives; forced oscillation; reduced velocity; turbulence model
 
Address
M. Keerthana and P. Harikrishna: Wind Engineering Laboratory, CSIR-Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai, India; Academy of Scientific and Innovative Research, India
 

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