Footbridge Response on Single Pedestrian Induced Vibration Analysis

Many footbridges have natural frequencies that coincide with the dominant frequencies of the pedestrian-induced load and therefore they have a potential to suffer excessive vibrations under dynamic loads induced by pedestrians. Some of the design standards introduce load models for pedestrian loads applicable for simple structures. Load modeling for more complex structures, on the other hand, is most often left to the designer. The main focus of this paper is on the human induced forces transmitted to a footbridge and on the ways these loads can be modeled to be used in the dynamic design of footbridges. Also design criteria and load models proposed by widely used standards were introduced and a comparison was made. The dynamic analysis of the suspension bridge in Kolin in the Czech Republic was performed on detailed FEM model using the ANSYS program system. An attempt to model the load imposed by a single person and a crowd of pedestrians resulted in displacements and accelerations that are compared with serviceability criteria.

Authors:

• J. Kala
• V. Salajka
• P. Hradil

Keywords:

• Footbridge
• Serviceability
• Pedestrian action
• Numerical analysis.

References:

[1] Bachmann, H. Lively Footbridges a Real Challenge. Proceedings of the
International Conference on the Design and Dynamic Behaviour of
Footbridges, Paris, France, November 20-22, 2002, pages 18-30.
[2] Dallard, P., Fitzpatrick, T., Flint, A., Low, A., Ridsdill Smith, R.,
Willford, M. and Roche, M. London Millennium Bridge: Pedestrian-
Induced Lateral Vibration. ASCE
[3] Design Manual for Road and Bridges: Loads for Highway Bridges: BD
37/01, Highway Agency, London, February, 2002.
[4] Eriksson, P. E. Vibration of Low-Frequency FloorsÔÇöDynamic Forces
and Response Prediction, PhD Thesis, Unit for Dynamics in Design,
Chalmers University of Technology, Goteborg, Sweden, 1994.
[5] Eurocode, Basis of Structural Design - prAnnex A2. EN1990: 2002.
European Committee for Standardization, Brussels, Belgium 2002.
[6] Eurocode 5, Design of Timber Structures Part 2: Bridges, EN1995- 2:
2004, European Committee for Standardization, Brussels, Belgium 2004.
[7] Grundmann, H. Kreuzinger, H., Schneider, M. Dynamic calculations of
footbridges, Bauingenieur 68 (1993) 215-225
[8] ISO, Bases for design of structures Serviceability of buildings and
pedestrian walkways against vibration, ISO/CD 10137, International
Stadardization Organization, Geneva, Switzerland, 2005.
[9] Ohlsson, S. V., Floor Vibration and Human Discomfort, PhD Thesis,
Chalmers University of Technology, Goteborg, Sweden, 1982 (in
English).
[10] SETRA, Footbridges, Assessment of vibrational behaviour of
footbridges under pedestrian loading, Technical guide SETRA, Paris,
France 2006.
[11] Young, P. Improved floor vibration prediction methodologies, ARUP
Vibration Seminar, October 4, 2001.
[12] Wheeler, J. E. Prediction and control of pedestrian induced vibration in
footbridges, ASCE Journal of the Structural Division 108 (ST9) (1982)
2045-2065.
[13] Zivanovic, S., Pavic, A., and Reynolds, P. Vibration serviceability of
footbridges under human-induced excitation: a literature review. Journal
og Sound and Vibration 279 (2005).