eprintid: 10080864 rev_number: 18 eprint_status: archive userid: 608 dir: disk0/10/08/08/64 datestamp: 2019-09-03 10:58:27 lastmod: 2021-09-26 23:11:27 status_changed: 2019-09-03 10:58:27 type: article metadata_visibility: show creators_name: Brownjohn, JMW creators_name: Raby, A creators_name: Au, SK creators_name: Zhu, Z creators_name: Wang, X creators_name: Antonini, A creators_name: Pappas, A creators_name: D'Ayala, D title: Bayesian operational modal analysis of offshore rock lighthouses: Close modes, alignment, symmetry and uncertainty ispublished: inpress divisions: UCL divisions: B04 divisions: C05 divisions: F44 keywords: Lighthouse condition assessment system, identification, BAYOMA, Close modes, OMA note: This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). 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. date: 2019-11-01 date_type: published official_url: https://doi.org/10.1016/j.ymssp.2019.106306 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1686309 doi: 10.1016/j.ymssp.2019.106306 lyricists_name: D'Ayala, Dina lyricists_name: Pappas, Athanasios lyricists_id: DDAYA16 lyricists_id: APAPP65 actors_name: Flynn, Bernadette actors_id: BFFLY94 actors_role: owner full_text_status: public publication: Mechanical Systems and Signal Processing volume: 133 article_number: 106306 issn: 1096-1216 citation: Brownjohn, JMW; Raby, A; Au, SK; Zhu, Z; Wang, X; Antonini, A; Pappas, A; Brownjohn, JMW; Raby, A; Au, SK; Zhu, Z; Wang, X; Antonini, A; Pappas, A; D'Ayala, D; - view fewer <#> (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 <https://doi.org/10.1016/j.ymssp.2019.106306>. (In press). Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10080864/1/1-s2.0-S0888327019305278-main.pdf