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Wind and Structures
  Volume 16, Number 2, February 2013 , pages 157-178
DOI: https://doi.org/10.12989/was.2013.16.2.157
 


Output-only modal parameter identification for force-embedded acceleration data in the presence of harmonic and white noise excitations
C.J. Ku, Y. Tamura, A. Yoshida, K. Miyake and L.S. Chou

 
Abstract
    Output-only modal parameter identification is based on the assumption that external forces on a linear structure are white noise. However, harmonic excitations are also often present in real structural vibrations. In particular, it has been realized that the use of forced acceleration responses without knowledge of external forces can pose a problem in the modal parameter identification, because an external force is imparted to its impulse acceleration response function. This paper provides a three-stage identification procedure as a solution to the problem of harmonic and white noise excitations in the acceleration responses of a linear dynamic system. This procedure combines the uses of the mode indicator function, the complex mode indication function, the enhanced frequency response function, an iterative rational fraction polynomial method and mode shape inspection for the correlation-related functions of the force-embedded acceleration responses. The procedure is verified via numerical simulation of a five-floor shear building and a two-dimensional frame and also applied to ambient vibration data of a large-span roof structure. Results show that the modal parameters of these dynamic systems can be satisfactorily identified under the requirement of wide separation between vibration modes and harmonic excitations.
 
Key Words
    acceleration; ambient vibration; correlation; excitations; frequency response; identification; modal model; mode indication function
 
Address
C.J. Ku, Y. Tamura and A. Yoshida : 1Department of Architectural Engineering, Tokyo Polytechnic University, Iiyama, Japan
K. Miyake: MHS Planners, Architects & Engineers, Tokyo, Japan
L.S. Chou: Yuh-Ing Junior College of Health Care & Management, General Education Center, Kaohsiung, Taiwan
 

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