Modal Identification of a Steel Platform Specimen with a Subspace Implementation of the Poly-reference Complex Frequency Method Formulated in Modal Model (pCF-MM)

When performing modal identification of structural systems, the main goal is to accurately extract the modal properties from the measured vibration data. The system identification can be carried out either in time or frequency-domain depending on the primary data used in the identification process, i.e., a time-domain free decay or frequency-domain function. In this paper, a subspace implementation of the new poly-reference Complex Frequency formulated in Modal Model (pCF-MM) is introduced. The technique operates in the frequency domain and uses either the Frequency Response Function or the Half Spectrum as primary data. The idea behind the subspace implementation of the pCF-MM is to use different subspaces of the observability and frequency-domain controlability matrices, carry out eigen-system realizations to estimate the modal properties corresponding to each chosen subspace. In order to illustrate its robustness, the subspace-driven pCF-MM is applied to the vibration data of a steel platform specimen to estimate its first vibration modes.