Abstract
The authors have been developing an anomaly detection system for road signs. As monitoring the acceleration responses, the temporal variations of vibration characteristics are contaminated by daily fluctuations due to the surrounding conditions. Therefore, in this research, a forced excitation experiment using a small vibrator was carried out for the road signs constructed in our campus, and the frequency transfer functions were accurately estimated with ARX method. And, a numerical model which is able to reproduce the frequency transfer function obtained by the forced excitation experiment was developed. The model parameters were determined to represent the averaged vibration characteristics. In addition, the effects of damage, temperature and base motion on natural frequency were studied using the numerical model developed in this research.
