Modal Identification Method Based on Natural Pulsation Excitation

It’s important to identify structural modal parameters, especially, accurate modal shapes in time domain for accurate damage identification and health monitoring of structures. The natural excitation vibration is used to identify the structural modal parameters. The power spectral density curve has obtained according to the measuring point vibration time domain curve, and then natural frequencies and vibration value are determined by the curve peak. The reference point is taken for the vibration unit values to normalize other modal shapes. The modal shapes are calculated using the phase measuring point relative to a reference point. After the finite element analysis and calculation, and the measured modal is compared with it. The results show that the dynamic performance of the bridge is reliable because the measurement method and the finite element method are basically consistent. The damping ratio of the bridge is larger dispersion but the average damping ratio is in line with the rules and scope of the cable-stayed bridge.