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Extraction of rational functions by forced vibration method for time-domain analysis of long-span bridges

  • Cao, Bochao (12271 Howe Hall, Department of Aerospace Engineering, Iowa State University) ;
  • Sarkar, Partha P. (12271 Howe Hall, Department of Aerospace Engineering, Iowa State University)
  • Received : 2011.09.12
  • Accepted : 2012.07.07
  • Published : 2013.06.25

Abstract

Rational Functions are used to express the self-excited aerodynamic forces acting on a flexible structure for use in time-domain flutter analysis. The Rational Function Approximation (RFA) approach involves obtaining of these Rational Functions from the frequency-dependent flutter derivatives by using an approximation. In the past, an algorithm was developed to directly extract these Rational Functions from wind tunnel section model tests in free vibration. In this paper, an algorithm is presented for direct extraction of these Rational Functions from section model tests in forced vibration. The motivation for using forced-vibration method came from the potential use of these Rational Functions to predict aerodynamic loads and response of flexible structures at high wind speeds and in turbulent wind environment. Numerical tests were performed to verify the robustness and performance of the algorithm under different noise levels that are expected in wind tunnel data. Wind tunnel tests in one degree-of-freedom (vertical/torsional) forced vibration were performed on a streamlined bridge deck section model whose Rational Functions were compared with those obtained by free vibration for the same model.

Keywords

References

  1. Bartoli, G., Contri, S., Mannini, C. and Righi, M. (2009), "Toward an improvement in the identification of bridge deck flutter derivatives", J. Eng. Mech.- ASCE, 135(8), 771-785. https://doi.org/10.1061/(ASCE)0733-9399(2009)135:8(771)
  2. Cao, B. and Sarkar, P.P. (2013), "Identification of rational functions using two-degree-of-freedom model by forced vibration method", Eng. Struct., (in press).
  3. Caracoglia, L. and Jones, N.P. (2003), "Time domain vs. frequency domain characterization of aeroelastic forces for bridge deck sections", J. Wind Eng. Ind. Aerod., 91, 371-402 https://doi.org/10.1016/S0167-6105(02)00399-9
  4. Chen, C., Wu, J. and Chen, J. (2008), "Prediction of flutter derivatives by artificial neural networks", J. Wind Eng. Ind. Aerod., 96, 1925-1937. https://doi.org/10.1016/j.jweia.2008.02.044
  5. Chen, X., Matsumoto, M. and Kareem, A. (2000), "Time domain flutter and buffeting response analysis of bridges", J. Eng. Mech. - ASCE, 126(1), 7-16. https://doi.org/10.1061/(ASCE)0733-9399(2000)126:1(7)
  6. Chen, X. and Kareem, A. (2002), "Advances in modeling of aerodynamic forces on bridge decks", J. Eng. Mech.- ASCE, 128(11), 1193-1205. https://doi.org/10.1061/(ASCE)0733-9399(2002)128:11(1193)
  7. Chen, X. and Kareem, A. (2008), "Identification of critical structural modes and flutter derivatives for predicting coupled bridge flutter", J. Wind Eng. Ind. Aerod., 96, 1856-1870. https://doi.org/10.1016/j.jweia.2008.02.025
  8. Ding, Q., Zhou, Z., Zhu, L. and Xiang, H. (2010), "Identification of flutter drivatives of bridge decks with free vibration technique", J. Wind Eng. Ind. Aerod., 98, 911-918. https://doi.org/10.1016/j.jweia.2010.09.005
  9. Gan Chowdhury, A. and Sarkar, P.P. (2003), "A new technique for identification of eighteen flutter derivatives using a three-degree-of-freedom section model", Eng. Struct., 25(14), 1763-1772. https://doi.org/10.1016/j.engstruct.2003.07.002
  10. Gan Chowdhury, A. (2004), Identification of Frequency domain and time domain aeroelastic parameters for flutter analysis of flexible structures, PhD dissertation. Ames (IA), Iowa State University.
  11. Gan Chowdhury, A. and Sarkar, P.P. (2004), "Identification of eighteen flutter derivatives of an airfoil and a bridge deck", Wind Struct., 7(3), 187-202. https://doi.org/10.12989/was.2004.7.3.187
  12. Gan Chowdhury, A. and Sarkar, P.P. (2005), "Experimental identification of rational function coefficients for time-domain flutter analysis", Eng. Struct., 27(9), 1349-1364. https://doi.org/10.1016/j.engstruct.2005.02.019
  13. Haan, F.L. (2000), The effects of turbulence on the aerodynamics of long-span bridges, Ph.D. dissertation. Notre Dame (IN, USA), University of Notre Dame.
  14. Karpel, M. (1982), "Design for active flutter suppression and gust alleviation using state-space aeroelastic modeling", J. Aircraft, 19(3), 221-227. https://doi.org/10.2514/3.57379
  15. Lin, Y.K. and Ariaratnam, S.T. (1980), "Stability of bridge motion in turbulent winds", J. Struct. Mech., 8(1), 1-15. https://doi.org/10.1080/03601218008907350
  16. Matsumoto, M. (1996), "Aerodynamic damping of prisms", J. Wind Eng. Ind. Aerod., 59(2-3),159-175. https://doi.org/10.1016/0167-6105(96)00005-0
  17. Roger, K. (1977), Airplane math modeling methods for active control design, AGARD-CP-228.
  18. Sarkar, P.P., Gan Chowdhury, A. and Gardner, T.B. (2004), "A novel elastic suspension system for wind tunnel section model studies", J. Wind Eng. Ind. Aerod., 92, 23-40. https://doi.org/10.1016/j.jweia.2003.09.036
  19. Sarkar, P.P., Caracoglia, L., Haan Jr., F.L., Sato, H. and Murakoshi, J. (2009), "Comparative and sensitivity study of flutter derivatives of selected bridge deck sections, Part1: Analysis of inter-laboratory experimental data", Eng. Struct., 31(1), 158-169. https://doi.org/10.1016/j.engstruct.2008.07.020
  20. Scanlan, R.H. and Tomko, J.J. (1971), "Airfoil and bridge deckflutter derivatives", J. Eng. Mech. Div., 97(6),1717-1733.
  21. Scanlan, R.H. (1993), "Problematics in formulation of wind-force models for bridge decks", J. Eng. Mech.- ASCE, 119(7), 1353-1375. https://doi.org/10.1061/(ASCE)0733-9399(1993)119:7(1353)
  22. Zhang, Z., Chen, Z., Cai, Y. and Ge, Y. (2011), "Indicial functions for bridge aeroelastic forces and time-domain flutter analysis", J. Bridge Eng.- ASCE, 16(4), 546-557. https://doi.org/10.1061/(ASCE)BE.1943-5592.0000176