TY  - INPR
N2  - 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.
ID  - discovery10080864
UR  - https://doi.org/10.1016/j.ymssp.2019.106306
SN  - 1096-1216
JF  - Mechanical Systems and Signal Processing
A1  - Brownjohn, JMW
A1  - Raby, A
A1  - Au, SK
A1  - Zhu, Z
A1  - Wang, X
A1  - Antonini, A
A1  - Pappas, A
A1  - D'Ayala, D
KW  - Lighthouse condition assessment system
KW  -  identification
KW  - 
BAYOMA
KW  -  Close modes
KW  -  OMA
TI  - Bayesian operational modal analysis of offshore rock lighthouses: Close modes, alignment, symmetry and uncertainty
AV  - public
VL  - 133
Y1  - 2019/11/01/
N1  - This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
ER  -