Civil Structural Health Monitoring Workshop. Berlin. Germany. 2012. Report. By using piezoelectric actuator real bridge can be accelerated locally to detect the effect of small damage like fatigue crack as a response change of vibration. Power spectrum density (PSD) function of the response can give us the indication of existence of damage before and after the damage. Detail comparison of PSD before and after damage can inform us location and size (area) of damage. Paper shows the experimental result of damage detection on real bridge.