Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment

James Brownjohn; Alison Raby; Siu Kui Au; Zuo Zhu; Xinrui Wang; Alessandro Antonini

Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment

James Brownjohn, Alison Raby, Siu Kui Au, Zuo Zhu, Xinrui Wang, Alessandro Antonini

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Abstract

A set of seven rock lighthouses around the British Isles was studied by a combination of forced and ambient vibration tests executed with some extreme logistical constraints. Forced vibration testing of the circular section masonry towers combined with experimental modal analysis identified modes with alignment assumed the same as the shaker as well as some interesting effects of helideck retrofit, whereas operational modal analysis revealed the considerable degree of uncertainty in mode shape alignment. Hence Bayesian operational modal analysis was used to characterise the uncertainty and find the best representation of mode shape direction. While perfectly axisymmetric towers would show a single frequency omnidirectional mode, OMA reveals the split modes and allows un unbiased view of directionality. The variability and uncertainty of these mode shape directions are further revealed using Bayesian OMA.

Original language	English
Title of host publication	8th IOMAC - International Operational Modal Analysis Conference, Proceedings
Editors	Sandro D. R. Amador, Rune Brincker, Evangelos I. Katsanos, Manuel Lopez Aenlle, Pelayo Fernandez
Publisher	International Operational Modal Analysis Conference (IOMAC)
Pages	9-16
Number of pages	8
ISBN (Electronic)	9788409049004
Publication status	Published - 2019
Externally published	Yes
Event	8th International Operational Modal Analysis Conference, IOMAC 2019 - Copengahen, Denmark Duration: May 13 2019 → May 15 2019

Publication series

Name	8th IOMAC - International Operational Modal Analysis Conference, Proceedings

Conference

Conference	8th International Operational Modal Analysis Conference, IOMAC 2019
Country/Territory	Denmark
City	Copengahen
Period	5/13/19 → 5/15/19

Bibliographical note

Publisher Copyright:
© 2019 International Group of Operational Modal Analysis.

ASJC Scopus Subject Areas

Instrumentation
Mechanics of Materials
Mechanical Engineering
Building and Construction

Keywords

Assessment
Bayesian
Condition
Identification
Lighthouse
OMA
System

Cite this

Brownjohn, J., Raby, A., Au, S. K., Zhu, Z., Wang, X., & Antonini, A. (2019). Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment. In S. D. R. Amador, R. Brincker, E. I. Katsanos, M. Lopez Aenlle, & P. Fernandez (Eds.), 8th IOMAC - International Operational Modal Analysis Conference, Proceedings (pp. 9-16). (8th IOMAC - International Operational Modal Analysis Conference, Proceedings). International Operational Modal Analysis Conference (IOMAC).

Brownjohn, James ; Raby, Alison ; Au, Siu Kui et al. / Bayesian oma of offshore rock lighthouses : Surprises with close modes, symmetry and alignment. 8th IOMAC - International Operational Modal Analysis Conference, Proceedings. editor / Sandro D. R. Amador ; Rune Brincker ; Evangelos I. Katsanos ; Manuel Lopez Aenlle ; Pelayo Fernandez. International Operational Modal Analysis Conference (IOMAC), 2019. pp. 9-16 (8th IOMAC - International Operational Modal Analysis Conference, Proceedings).

@inproceedings{2a1de68612ed417e9749edf1e878b4cf,

title = "Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment",

abstract = "A set of seven rock lighthouses around the British Isles was studied by a combination of forced and ambient vibration tests executed with some extreme logistical constraints. Forced vibration testing of the circular section masonry towers combined with experimental modal analysis identified modes with alignment assumed the same as the shaker as well as some interesting effects of helideck retrofit, whereas operational modal analysis revealed the considerable degree of uncertainty in mode shape alignment. Hence Bayesian operational modal analysis was used to characterise the uncertainty and find the best representation of mode shape direction. While perfectly axisymmetric towers would show a single frequency omnidirectional mode, OMA reveals the split modes and allows un unbiased view of directionality. The variability and uncertainty of these mode shape directions are further revealed using Bayesian OMA.",

keywords = "Assessment, Bayesian, Condition, Identification, Lighthouse, OMA, System",

author = "James Brownjohn and Alison Raby and Au, {Siu Kui} and Zuo Zhu and Xinrui Wang and Alessandro Antonini",

note = "Publisher Copyright: {\textcopyright} 2019 International Group of Operational Modal Analysis.; 8th International Operational Modal Analysis Conference, IOMAC 2019 ; Conference date: 13-05-2019 Through 15-05-2019",

year = "2019",

language = "English",

series = "8th IOMAC - International Operational Modal Analysis Conference, Proceedings",

publisher = "International Operational Modal Analysis Conference (IOMAC)",

pages = "9--16",

editor = "Amador, {Sandro D. R.} and Rune Brincker and Katsanos, {Evangelos I.} and {Lopez Aenlle}, Manuel and Pelayo Fernandez",

booktitle = "8th IOMAC - International Operational Modal Analysis Conference, Proceedings",

}

Brownjohn, J, Raby, A, Au, SK, Zhu, Z, Wang, X & Antonini, A 2019, Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment. in SDR Amador, R Brincker, EI Katsanos, M Lopez Aenlle & P Fernandez (eds), 8th IOMAC - International Operational Modal Analysis Conference, Proceedings. 8th IOMAC - International Operational Modal Analysis Conference, Proceedings, International Operational Modal Analysis Conference (IOMAC), pp. 9-16, 8th International Operational Modal Analysis Conference, IOMAC 2019, Copengahen, Denmark, 5/13/19.

Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment. / Brownjohn, James; Raby, Alison; Au, Siu Kui et al.
8th IOMAC - International Operational Modal Analysis Conference, Proceedings. ed. / Sandro D. R. Amador; Rune Brincker; Evangelos I. Katsanos; Manuel Lopez Aenlle; Pelayo Fernandez. International Operational Modal Analysis Conference (IOMAC), 2019. p. 9-16 (8th IOMAC - International Operational Modal Analysis Conference, Proceedings).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - Bayesian oma of offshore rock lighthouses

T2 - 8th International Operational Modal Analysis Conference, IOMAC 2019

AU - Brownjohn, James

AU - Raby, Alison

AU - Au, Siu Kui

AU - Zhu, Zuo

AU - Wang, Xinrui

AU - Antonini, Alessandro

PY - 2019

Y1 - 2019

N2 - A set of seven rock lighthouses around the British Isles was studied by a combination of forced and ambient vibration tests executed with some extreme logistical constraints. Forced vibration testing of the circular section masonry towers combined with experimental modal analysis identified modes with alignment assumed the same as the shaker as well as some interesting effects of helideck retrofit, whereas operational modal analysis revealed the considerable degree of uncertainty in mode shape alignment. Hence Bayesian operational modal analysis was used to characterise the uncertainty and find the best representation of mode shape direction. While perfectly axisymmetric towers would show a single frequency omnidirectional mode, OMA reveals the split modes and allows un unbiased view of directionality. The variability and uncertainty of these mode shape directions are further revealed using Bayesian OMA.

AB - A set of seven rock lighthouses around the British Isles was studied by a combination of forced and ambient vibration tests executed with some extreme logistical constraints. Forced vibration testing of the circular section masonry towers combined with experimental modal analysis identified modes with alignment assumed the same as the shaker as well as some interesting effects of helideck retrofit, whereas operational modal analysis revealed the considerable degree of uncertainty in mode shape alignment. Hence Bayesian operational modal analysis was used to characterise the uncertainty and find the best representation of mode shape direction. While perfectly axisymmetric towers would show a single frequency omnidirectional mode, OMA reveals the split modes and allows un unbiased view of directionality. The variability and uncertainty of these mode shape directions are further revealed using Bayesian OMA.

KW - Assessment

KW - Bayesian

KW - Condition

KW - Identification

KW - Lighthouse

KW - OMA

KW - System

UR - http://www.scopus.com/inward/record.url?scp=85069432271&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85069432271&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:85069432271

T3 - 8th IOMAC - International Operational Modal Analysis Conference, Proceedings

SP - 9

EP - 16

BT - 8th IOMAC - International Operational Modal Analysis Conference, Proceedings

A2 - Amador, Sandro D. R.

A2 - Brincker, Rune

A2 - Katsanos, Evangelos I.

A2 - Lopez Aenlle, Manuel

A2 - Fernandez, Pelayo

PB - International Operational Modal Analysis Conference (IOMAC)

Y2 - 13 May 2019 through 15 May 2019

ER -

Brownjohn J, Raby A, Au SK, Zhu Z, Wang X, Antonini A. Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment. In Amador SDR, Brincker R, Katsanos EI, Lopez Aenlle M, Fernandez P, editors, 8th IOMAC - International Operational Modal Analysis Conference, Proceedings. International Operational Modal Analysis Conference (IOMAC). 2019. p. 9-16. (8th IOMAC - International Operational Modal Analysis Conference, Proceedings).

Bayesian oma of offshore rock lighthouses: Surprises with close modes, symmetry and alignment

Abstract

Publication series

Conference

Bibliographical note

ASJC Scopus Subject Areas

Keywords

Other files and links

Fingerprint

Cite this