HYBRID TIME AND FREQUENCY DOMAIN TECHNIQUE ON MODAL IDENTIFICATION USING AMBIENT VIBRATION TESTS

摘要

In this paper, in order to identify the modal properties of a structure based on the ambient vibrationnmonitoring, an innovative method for modal identification, called Hybrid Time and Frequency DomainnAnalysis, is described and a full scale test is presented. The method consists of frequency domain analysisnfor natural frequencies and modal shapes identification; and time domain analysis for the damping estimation.nThe methodology was tested in a 5 story steel frame structure constructed at the Disaster PreventnResearch Institute, Kyoto University, Japan, using ambient vibration testing. The dynamic response wasnmeasured with simultaneous sensors in every floor, including ground. The modal shapes results werencompared with the FEM and with previous results obtained from monitoring under forced vibration. Fornthe damping estimation, free vibration results were compared with the ambient vibration test. The systemnidentification obtained under ambient vibration tests are in very good agreement with the forced and freenvibration tests and with the analytical results.