Wind and Structures

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Effects of frequency ratio on bridge aerodynamics determined by free-decay sectional model tests

  • Qin, X.R. (CLP Power Wind/Wave Tunnel Facility, HKUST) ;
  • Kwok, K.C.S. (CLP Power Wind/Wave Tunnel Facility, HKUST) ;
  • Fok, C.H. (CLP Power Wind/Wave Tunnel Facility, HKUST) ;
  • Hitchcock, P.A. (CLP Power Wind/Wave Tunnel Facility, HKUST)
  • Received : 2008.03.14
  • Accepted : 2009.05.12
  • Published : 2009.09.25
⟨ Previous Next ⟩

Abstract

A series of wind tunnel free-decay sectional model dynamic tests were conducted to examine the effects of torsional-to-vertical natural frequency ratio of 2DOF bridge dynamic systems on the aerodynamic and dynamic properties of bridge decks. The natural frequency ratios tested were around 2.2:1 and 1.2:1 respectively, with the fundamental vertical natural frequency of the system held constant for all the tests. Three 2.9 m long twin-deck bridge sectional models, with a zero, 16% (intermediate gap) and 35% (large gap) gap-to-width ratio, respectively, were tested to determine whether the effects of frequency ratio are dependent on bridge deck cross-section shapes. The results of wind tunnel tests suggest that for the model with a zero gap-width, a model to approximate a thin flat plate, the flutter derivatives, and consequently the aerodynamic forces, are relatively independent of the torsional-to-vertical frequency ratio for a relatively large range of reduced wind velocities, while for the models with an intermediate gap-width (around 16%) and a large gap-width (around 35%), some of the flutter derivatives, and therefore the aerodynamic forces, are evidently dependent on the frequency ratio for most of the tested reduced velocities. A comparison of the modal damping ratios also suggests that the torsional damping ratio is much more sensitive to the frequency ratio, especially for the two models with nonzero gap (16% and 35% gap-width). The test results clearly show that the effects of the frequency ratio on the flutter derivatives and the aerodynamic forces were dependent on the aerodynamic cross-section shape of the bridge deck.

Keywords

References

  1. Brownjohn, J.M.W. and Bogunovic Jakobsen, J. (2001), "Strategies for aeroelastic parameter identification from bridge deck free vibration data", J. Wind Eng. Ind. Aerod., 89, 1113-1136. https://doi.org/10.1016/S0167-6105(01)00091-5
  2. Chen, X.Z., Matsumoto, M. and Kareem, A. (2000), "Aerodynamic coupling effects on flutter and buffeting of bridges", J. Eng. Mech. ASCE, 126(1), 17-26. https://doi.org/10.1061/(ASCE)0733-9399(2000)126:1(17)
  3. Curami, A. and Zasso, A. (1993), "Extensive identification of bridge deck aeroelastic coefficients: average angle of attack, Reynolds number and other parameter effects", Proc. of the 3rd Asia-Pacific Symposium on Wind Engineering, Hong Kong, pp. 143-148.
  4. Diana, G., Resta, F., Zasso, F., Belloli, M. and Rocchi, D. (2004), "Forced motion and free motion aeroelastic tests on a new concept dynamometric section model of the Messina suspension bridge", J. Wind Eng. Ind. Aerod., 92, 441-462. https://doi.org/10.1016/j.jweia.2004.01.005
  5. Gu, M., Zhang, R.X. and Xiang, H.F. (2000), "Identification of flutter derivatives of bridge decks", J. Wind Eng. Ind. Aerod., 84, 151-162. https://doi.org/10.1016/S0167-6105(99)00051-3
  6. Gu, M., Zhang, R.X. and Xiang, H.F. (2001), "Parametric study of flutter derivatives of bridge decks", Eng. Struct., 23, 1607-1613. https://doi.org/10.1016/S0141-0296(01)00059-1
  7. Juang, J.N. and Pappa, R.S. (1985), "An eigensystem realization algorithm for modal parameter identification and model reduction", J. Guid. Control Dynam., 8(5), 620-627. https://doi.org/10.2514/3.20031
  8. Matsumoto, M., Shiraishi, N., Shirato, H., Shigetaka, K. and Niihara, Y. (1993), "Aerodynamic derivatives of coupled/hybrid flutter of fundamental structural sections", J. Wind Eng. Ind. Aerod., 49, 575-584. https://doi.org/10.1016/0167-6105(93)90051-O
  9. Matsumoto, M., Shijo, R., Eguchi, A., Hikida, T., Tamaki, H. and Mizuno, K. (2004), "On the flutter characteristics of the separated two box girders", Wind Struct., 7(4), 281-291. https://doi.org/10.12989/was.2004.7.4.281
  10. Matsumoto, M., Shirato, H., Mizuno, K., Shijo, R. and Hikida, T. (2008), "Flutter characteristics of H-shaped cylinders with various side-ratios and comparisons with characteristics of rectangular cylinders", J. Wind Eng. Ind. Aerod., 96, 963-970. https://doi.org/10.1016/j.jweia.2007.06.022
  11. Noda, M., Utsunomiya, H., Nagao, F., Kanda, M. and Shiraishi, N. (2003), "Effects of oscillation amplitude on aerodynamic derivatives", J. Wind Eng. Ind. Aerod., 91, 101-111. https://doi.org/10.1016/S0167-6105(02)00338-0
  12. Qin, X.R., Kwok, K.C.S., Fok, C.H., Hitchcock, P.A. and Xu, Y.L. (2007), "Wind-induced self-excited vibrations of a twin-deck bridge and the effects of gap-width", Wind Struct., 10(5), 463-479. https://doi.org/10.12989/was.2007.10.5.463
  13. Qin, X.R. and Gu, M. (2004), "Determination of flutter derivatives by stochastic subspace identification technique", Wind Struct., 7(3), 173-186. https://doi.org/10.12989/was.2004.7.3.173
  14. Qin, X.R., Kwok, K.C.S., Fok, C.H. and Hitchcock, P.A. (2004), "Wind-induced vibrations of a twin-deck bridge model", Proc. of the 6th Asia-Pacific Conf. on Wind Engineering, Korea, pp. 340-348.
  15. Sarkar, P.P. (1994), "Identification of aeroelastic parameter of flexible bridges", J. Eng. Mech. ASCE, 120(8), 1718-1741. https://doi.org/10.1061/(ASCE)0733-9399(1994)120:8(1718)
  16. Sato, H., Kusuhara, H., Ogi, K. and Matsufuji, H. (2000), "Aerodynamic characteristics of super long-span bridges with slotted box girder", J. Wind Eng. Ind. Aerod., 8(8), 297-306.
  17. Scanlan, R.H. (1978), "The action of flexible bridges under wind, I: flutter theory", J. Sound Vib., 60(2), 187-199. https://doi.org/10.1016/S0022-460X(78)80028-5
  18. Scanlan, R.H. and Tomko, J.J. (1971), "Airfoil and bridge deck flutter derivatives", J. Eng. Mech. ASCE, 97(6), 1717-1737.
  19. Singh, L., Jones, N.P., Scanlan, R.H. and Lorendeaux, O. (1996), "Identification of lateral flutter derivatives of bridge decks", J. Wind Eng. Ind. Aerod., 60, 81-89. https://doi.org/10.1016/0167-6105(96)00025-6
  20. Zhang, X., Mark, J. and Brownjohn, W. (2004), "Effect of relative amplitude on bridge deck flutter", J. Wind Eng. Ind. Aerod., 91, 101-111.

Cited by

  1. An enhanced forced vibration rig for wind tunnel testing of bridge deck section models in arbitrary motion vol.164, 2017, https://doi.org/10.1016/j.jweia.2017.02.011
  2. Theoretical research on the identification method of bridge dynamic parameters using free decay response vol.38, pp.3, 2009, https://doi.org/10.12989/sem.2011.38.3.349
  3. Modeling of self-excited forces during multimode flutter: an experimental study vol.27, pp.5, 2009, https://doi.org/10.12989/was.2018.27.5.293