Identification of friction-coupled offshore platforms by output-only method

Tobias Friis, Karsten K. Vesterholm, Evangelos I. Katsanos, Anders Brandt, Rune Brincker

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


    A structural health monitoring (SHM) program can improve the structural integrity of offshore structures, however, the SHM scheme implies extraction of linear time-invariant modal parameters by Operational Modal Analysis (OMA). Inherently, the offshore platforms are nonlinear, and in many cases, the dynamics of the platforms are involving a friction-induced coupling that stems from bearings in the bridges connecting the platforms. This mechanism is causing the platforms to interchange between acting either as one system or separate systems, depending on the sliding or sticking state of the bearings. Along these lines, the present paper proposes an identification framework employing nonlinearity optimised random decrement (NORD) and OMA parameter estimation methods to identify two sets of underlying linear modes, relative to the state of the friction-induced coupling, both from the same measurement record.
    Original languageEnglish
    Title of host publicationProceedings of the 29th International Ocean and Polar Engineering Conference
    Number of pages6
    PublisherInternational Society of Offshore & Polar Engineers
    Publication date2019
    ISBN (Electronic)978-1-880653-85-2
    Publication statusPublished - 2019
    Event29th International Ocean and Polar Engineering Conference (ISOPE 2019) - Honolulu, United States
    Duration: 16 Jun 201921 Jun 2019


    Conference29th International Ocean and Polar Engineering Conference (ISOPE 2019)
    Country/TerritoryUnited States


    • Operational modal analysis
    • Response dependent identification
    • Friction-coupled systems
    • Nonlinear dynamics
    • Random decrement technique
    • Nonlinearity optimised random decrement
    • NORD


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