A comparative assessment of in-operation modal analysis and frequency domain decomposition algorithm using simulated data

Abstract

Recently a new In-Operation modal identification algorithm has been proposed by one of the authors (INOPMA). The algorithm is based on considering the correlation sequence of the outputs of the structure as an impulse response but with a certain phase shift. A numerical modal appropriation is then performed and it is shown that a mode is isolated at a certain characteristic frequency. The estimation of the modal parameters is then done in a standard way. We investigate in this paper the performance of INOPMA under realistic excitation and we compare it to the Frequency Domain Decomposition algorithm (FDD). The example is a 3DOF system under El-Centro seismic excitation. It is shown that both methods perform equally well.