Evaluation of Damping Using Frequency Domain Operational Modal Analysis Techniques

Anela Bajric, Christos T. Georgakis, Rune Brincker

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


Operational Modal Analysis (OMA) techniques provide in most cases reasonably accurate estimates of structural frequencies and mode shapes. In contrast though, they are known to often produce uncertain structural damping estimates,
which is mainly due to inherent random and/or bias errors. In this paper a comparison is made of the effectiveness of two existing OMA techniques in providing accurate damping estimates for random stationary loading, varying levels of signal noise, number of added measurement channels and level of structural damping. The investigation is focusing on the two frequency domain techniques, the Frequency Domain Decomposition (FDD) and the Frequency Domain Polyreference (FDPR). The response of a two degree-of-freedom (2DOF) system is numerically established with specified modal parameters subjected to white noise loading. The system identification is evaluated with well separated and closely spaced modes. Finally, the results of the numerical study are presented, in which the error of the structural damping estimates obtained by each OMA technique is shown for a range of damping levels. From this, it is clear that there are notable differences in accuracy between the different techniques.
Original languageEnglish
Title of host publicationDynamics of Civil Structures : Proceedings of the 33rd IMAC, A Conference and Exposition on Structural Dynamics, 2015
Publication date2015
ISBN (Print)978-3-319-15247-9
ISBN (Electronic)978-3-319-15248-6
Publication statusPublished - 2015
EventIMAC XXXIII Conference and Exposition on Structural Dynamics: Balancing Simulation and Testing - Orlando, United States
Duration: 2 Feb 20155 Feb 2015
Conference number: 33


ConferenceIMAC XXXIII Conference and Exposition on Structural Dynamics
Country/TerritoryUnited States


  • Operational Modal Analysis
  • Structural damping
  • Frequency Domain Decomposition
  • Frequency Domain Polyreference
  • Closely spaced modes


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