Dynamic Characterization of the Little Belt Suspension Bridge by Operational Modal Analysis

  • Silas S. Christensen
  • Michael S. Andersen
  • Anders Brandt
Conference paper
Part of the Conference Proceedings of the Society for Experimental Mechanics Series book series (CPSEMS)


The (new) Little Belt Bridge, opened in 1970, is a Danish suspension bridge with largest span being 600 m, and a total length of 1700 m. During the design and construction phase, detailed analysis of the dynamic properties of the bridge were carried out both by hand calculations and by measurements on a scale model. Recently, the bridge was measured using a setup of 45 simultaneous responses, 30 vertical and 15 lateral, distributed over the main span. Operational modal analysis was carried out on the data set, and the first two vertical bending and torsional modes were compared to those of the model. It was found that the first vertical bending mode was 0.156 Hz, which is very near the frequency predicted by the original scale model. In total nine modes are reported, with frequencies from 0.156 to 0.808 Hz, and with damping values between 0.38% and 9.74%. This paper also demonstrates and discusses the use of inexpensive geophones and general measurement equipment for use in OMA applications based on the experience from this bridge measurement.


Dynamic characterization Little belt suspension bridge Operational modal analysis Multi-reference Ibrahim time domain 



We would like to thank The Danish Road Directorate for their help during the measurement campaign. We would also greatly want to thank Hilde Husby Knustad for producing good measurements.


  1. 1.
    Ostenfeld, C., Haas, G., Frandsen, A.G.: Motorway bridge across Lilleblt: model tests for the superstructure of the suspension bridge. Presented at Symposium on Supension Bridges, Lisbon (1966)Google Scholar
  2. 2.
    Theodorsen, T.: General theory of aerodynamic instability and the mechanism of Flutter. NACA report (1934)Google Scholar
  3. 3.
    Allemang, R.J., Brown, D.L.: A unified matrix polynomial approach to modal identification. J. Sound Vib. 221(3), 301–322 (1998)CrossRefGoogle Scholar
  4. 4.
    Peeters, B., Roeck, G.D.: Stochastic system identification for operational modal analysis: a review. J. Dyn. Syst. Meas. Control 123(4), 659–667 (2001)CrossRefGoogle Scholar
  5. 5.
    Brincker, R., Ventura, C.: Introduction to Operational Modal Analysis. Wiley, New York (2015)CrossRefGoogle Scholar
  6. 6.
    Ibrahim, S.R., Mikulcik, E.C.: A method for the direct identification of vibration parameters from the free response. Shock Vib. Bull. 47, 183–198 (1977)Google Scholar
  7. 7.
    Fukuzono, K.: Investigation of multiple-reference Ibrahim Time Domain modal parameter estimation technique. Master’s thesis, University of Cincinnati (1986)Google Scholar
  8. 8.
    Brandt, A.: Noise and Vibration Analysis – Signal Analysis and Experimental Procedures. Wiley, New York (2011)CrossRefGoogle Scholar
  9. 9.
    Knustad, H.H.: Operational modal analysis of the Little Belt Bridge using geophones. Master’s thesis, University of Southern Denmark (2015)Google Scholar
  10. 10.
    Brandt, A.: ABRAVIBE A MATLAB toolbox for noise and vibration analysis and teaching. Department of Technology and Innovation, University of Southern Denmark (2011).
  11. 11.
    Orlowitz, E., Brandt, A.: Influence of Noise in Correlation Function Estimates for Operational Modal Analysis. XXXVI International Modal Analysis Conference (2018)Google Scholar
  12. 12.
    Brownjohn, J.M.W., Magalhaes, F., Caetano, E., Cunha, A.: Ambient vibration re-testing and operational modal analysis of the Humber Bridge. J. Eng. Struct. 32, 2003–2018 (2010)CrossRefGoogle Scholar

Copyright information

© The Society for Experimental Mechanics, Inc. 2019

Authors and Affiliations

  • Silas S. Christensen
    • 1
  • Michael S. Andersen
    • 1
  • Anders Brandt
    • 1
  1. 1.Department of Technology and InnovationUniversity of Southern DenmarkOdense MDenmark

Personalised recommendations