Comparison between two methods in frequency domain for dynamic identification

The aim of this paper is the application of two different methods, able to extract the modal parameters of a generic structure, subjected to vibration test. The two procedures work both in the frequency domain and they are applied in the case of forced vibration test, carried out on real buildings. The first method is based on the construction point by point of the FRF (inertance)through the computation of the Fast Fourier Transform (FFT) of the output signal, acquired as acceleration. When the FRF is defined, the modal parameters of the system are extracted through classical Peak Picking method. The proposed methodology can define also an index of the correlation between the structure reply registered in correspondence of each accelerometer and the perfectly sinusoidal force applied by the vibrodyna.