Seismic modal identification using a new approach based on weighted transmissibility

Abstract

AbstractIn recent years, the transmissibility‐based operational modal analysis has attracted the attention of many researchers due to its effective applications in output‐only modal identification. However, the present research indicates that the application of this approach is not so appropriate for the ambient vibration records with short length and high spectral leakage, such as seismic records. The existence of nonperiodic frequency components in the records leads to an increase in the spectral leakage and dispersion. In this paper, an effective approach called weighted transmissibility‐based operational modal analysis is proposed to properly identify the structural modal parameters using the seismic records. The proposed method identifies the natural frequencies and mode shapes based on weighed transmissibility, so that it combines the single‐reference weighted transmissibility functions associated with different transferring outputs obtained from single or multiple loading conditions in a unique matrix formulation. Then, it extracts the vibration modes using the efficient spectra obtained from the singular value decomposition of weighted transmissibility matrices. In this paper, a theoretical example (5DOF system) is provided to indicate the capabilities of the proposed approach for identifying the modal parameters of structural systems.