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Wind and Structures
  Volume 34, Number 4, April 2022 , pages 355-369

Reynolds number and scale effects on aerodynamic properties of streamlined bridge decks
Tingting Ma and Chaotian Feng

    Section model test, as the most commonly used method to evaluate the aerostatic and aeroelastic performances of long-span bridges, may be carried out under different conditions of incoming wind speed, geometric scale and wind tunnel facilities, which may lead to potential Reynolds number (Re) effect, model scaling effect and wind tunnel scale effect, respectively. The Re effect and scale effect on aerostatic force coefficients and aeroelastic characteristics of streamlined bridge decks were investigated via 1:100 and 1:60 scale section model tests. The influence of auxiliary facilities was further investigated by comparative tests between a bare deck section and the deck section with auxiliary facilities. The force measurement results over a Re region from about 1x105 to 4x105 indicate that the drag coefficients of both deck sections show obvious Re effect, while the pitching moment coefficients have weak Re dependence. The lift coefficients of the smaller scale models have more significant Re effect. Comparative tests of different scale models under the same Re number indicate that the static force coefficients have obvious scale effect, which is even more prominent than the Re effect. Additionally, the scale effect induced by lower model length to wind tunnel height ratio may produce static force coefficients with smaller absolute values, which may be less conservative for structural design. The results with respect to flutter stability indicate that the aerodynamic-dampingrelated flutter derivatives A2* and A*1H*3 have opposite scale effect, which makes the overall scale effect on critical flutter wind speed greatly weakened. The most significant scale effect on critical flutter wind speed occurs at +3° wind angle of attack, which makes the smallscale section models give conservative predictions.
Key Words
    auxiliary facilities; bridge; flutter; Reynolds number effect; scale effect; static force coefficients; wind-tunnel test
Tingting Ma and Chaotian Feng: College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, China

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