In this study, the validity of the damage identification technique that uses Fourier amplitude ratios due to unknown excitation force was confirmed based on the vibration testing using a real bridge. The technique is based on the fact that the ratio of Fourier amplitudes at two points when they are measured simultaneously is constant regardless of the amplitude of the excitation force. The bridge was excited using a micro shaker and the excitation force is clearly known, but we did not use it as input data for the technique. Damage was modeled as a reduction in stiffness and created by reducing the section area of diagonal members of the bridge. It was shown that the damaged elements were correctly identified using the technique.
