Dynamic characteristics of multiple substructures with closely spaced frequencies

Kangming Xu, Takeru Igusa

Research output: Contribution to journalArticlepeer-review

302 Scopus citations


This paper considers a main structure supporting a large number of substructures. The substructures have closely spaced natural frequencies, and the combined main structure/multiple substructures system is subjected to harmonic or wide‐band forces. The goal is to characterize the effects of the substructures on the response of the main structure. A special, fundamental case is studied in detail, where the substructures are oscillators with equal stiffnesses and equally spaced natural frequencies. The exact response expressions for the combined system are in terms of a complicated rational polynomial. However, by taking the limit where the number of substructures becomes large, the response expressions reduce to simple, physically meaningful results. It is found that the multiple substrutures are equivalent to a single viscous damping which is added to the damping of the main structure. An example illustrates how the results can be applied to passive vibration control of large structures.

Original languageEnglish (US)
Pages (from-to)1059-1070
Number of pages12
JournalEarthquake Engineering & Structural Dynamics
Issue number12
StatePublished - 1992
Externally publishedYes

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Earth and Planetary Sciences (miscellaneous)
  • Civil and Structural Engineering


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