Brownjohn, JMW;
Raby, A;
Au, SK;
Zhu, Z;
Wang, X;
Antonini, A;
Pappas, A;
(2019)
Bayesian operational modal analysis of offshore rock lighthouses: Close modes, alignment, symmetry and uncertainty.
Mechanical Systems and Signal Processing
, 133
, Article 106306. 10.1016/j.ymssp.2019.106306.
(In press).
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Abstract
Despite use of GPS, lighthouses remain critical infrastructure for preserving safety of mariners and maritime trade, and the most dramatic examples are probably the Victorian era masonry towers located on remote offshore reefs around the British Isles and exposed to extreme weather conditions. Due to their age and likely increasing future loading, dynamic field investigations were undertaken for condition assessment. The field investigations of a sample of seven lighthouses had focused on experimental modal analysis (EMA) of shaker force and acceleration response data in order to identify sets of modal parameters (MPs) specifically including modal mass, which is useful for linking loading and response. However, the EMA missed significant useful information, which could be recovered from operational modal analysis (OMA) of additional ambient vibration data recorded during the field measurements, as well as from subsequent long-term monitoring of Wolf Rock lighthouse. Horizontal vibration modes of the towers appear as pairs of modes of similar shape and with close natural frequency due to the quasi-axisymmetric structural form(s), and the lowest frequency pairs are most important to identify since they contribute most to response to breaking wave impact loads. Reliably identifying both the close natural frequencies and the corresponding mode shape orientations was impossible with EMA.
| Type: | Article |
|---|---|
| Title: | Bayesian operational modal analysis of offshore rock lighthouses: Close modes, alignment, symmetry and uncertainty |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.ymssp.2019.106306 |
| Publisher version: | https://doi.org/10.1016/j.ymssp.2019.106306 |
| Language: | English |
| Additional information: | This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
| Keywords: | Lighthouse condition assessment system, identification, BAYOMA, Close modes, OMA |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10080864 |
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