Application of subspace identification technique to long-term seismic response monitoring of structures

This paper addresses the issue of structural system identification using earthquake-induced structural response. The proposed methodology is based on the subspace identification algorithm to perform identification of structural dynamic characteristics using input-output seismic response data. Incorporated with subspace identification algorithm, a scheme to remove spurious modes is also used to identify real system poles. The efficiency of the proposed method is shown by the analysis of all measurement data from all measurement directly. The recorded seismic response data of three structures (one 7-story RC building, one midisolation building, and one isolated bridge), under Taiwan Strong Motion Instrumentation Program, are analyzed during the past 15years. The results present the variation of the identified fundamental modal frequencies and damping ratios from all the recorded seismic events that these three structures had encountered during their service life. Seismic assessment of the structures from the identified system dynamic characteristics during the period of their service is discussed. Copyright (c) 2014 John Wiley & Sons, Ltd.