A spectral pedestrian-based approach for modal identification

Alani, Amir, Jesus, Andre ORCID: https://orcid.org/0000-0002-5194-3469 and Živanović, Stana (2019) A spectral pedestrian-based approach for modal identification. Journal of Sound and Vibration, 470. ISSN 0022-460X

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Abstract

The dynamic behaviour of footbridges is characterised by modal properties such as natural frequencies, mode shapes, damping ratios and modal masses. Their estimation via modal tests often requires expensive or difficult-to-operate equipment (e.g. shaker and instrumented impact hammer) or, sometimes unavailable high signal-to-noise ratios in tests relying on natural (e.g. wind, airborne noise and ground-borne vibration) excitation. In addition, the modal properties determined in modal tests do not necessarily apply to the structure under pedestrian traffic in case of amplitude-dependent frequencies and damping ratios. The current work proposes a novel approach that stands in contrast to the widely used tests, based on modal identification using an excitation induced by a single pedestrian. In order to account for estimation and observation uncertainties, the relationship between the power spectrum of the response and its modal properties is described with a likelihood function. It is shown that it is possible to reliably estimate modal properties using pedestrian walk forces measured in the laboratory, and dynamic responses measured when the same pedestrian is crossing a footbridge at timed pacing rates. The approach is validated using numerical and field data for a 16.9 m long fibre reinforced polymer footbridge. This work paves a new way for simple and low cost modal testing in structural dynamics.

Item Type: Article
Additional Information: The authors would like to thank the anonymous reviewers/editor and Julia Dinan for feedback on the manuscript. The research in this paper was partially supported by the UK Engineering and Physical Sciences Research Council (grant number EP/M021505/1 Characterising dynamic performance of fibre reinforced polymer structures for resilience and sustainability).
Uncontrolled Keywords: Power spectral density, Modal identification, FRP footbridge, Pedestrian excitation, Metropolis–Hastings, Likelihood function
Subjects: Construction and engineering > Civil and structural engineering
Construction and engineering
Depositing User: Camille Regnault
Date Deposited: 02 Jan 2020 11:07
Last Modified: 11 Feb 2020 11:54
URI: http://repository.uwl.ac.uk/id/eprint/6659

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