Lateral human-structure interaction on footbridges

Einar Thór Ingólfsson, Christos Georgakis, Francesco Ricciardelli, Lorenzo Procino

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

In recent years, several high-profile footbridges have suffered from unexpected excessive pedestrian-induced lateral vibrations. There is a commonly accepted view that the synchronisation of pedestrians to the lateral movement of a structure is necessary for the onset of a form of instability which may lead to large lateral responses. Several recently published load models are based on this assumption. Yet, few experimental studies exist to support this hypothesis. Therefore, an extensive experimental campaign, involving 71 test subjects, has been carried out to determine the lateral forces generated by pedestrians during walking on an instrumented moving treadmill. The treadmill was driven sinusoidally in a lateral motion at various vibration frequencies and amplitudes. Visual observations made during the experiments and testimonies from the walkers, as well as subsequent analysis of video recordings, suggested that synchronisation is not as pronounced as generally believed. To confirm this, further analyses were undertaken on the walking patterns of 10 test subjects that were instrumented with waist-mounted tri-axial accelerometers. In this paper, the results from these tests are presented. The tests reveal that synchronisation is not a pre-condition for the development of large amplitude lateral vibrations on footbridges, as walking frequencies and phase angles remain largely unaffected by lateral motion at most frequencies and amplitudes. Instead, large amplitude vibrations are the result of correlated pedestrian forces in the form of "negative damping" that can be generated at all frequencies.
Original languageEnglish
Title of host publication10th International Conference on Recent Advances in Structural Dynamics
Publication date2010
Publication statusPublished - 2010
Event10th International Conference on Recent Advances in Structural Dynamics - Southampton, United Kingdom
Duration: 12 Jul 201014 Jul 2010
Conference number: 10

Conference

Conference10th International Conference on Recent Advances in Structural Dynamics
Number10
CountryUnited Kingdom
CitySouthampton
Period12/07/201014/07/2010

Keywords

  • Footbridge, human-structure interaction, lateral vibration, synchronisation

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