Feasibility Study on Structural Health Monitoring for Cantilevered Highway Sign

This paper describes the results of feasibility study on the structural health monitoring for the cantilevered highway signs. In this study, tri-axial accelerometers were installed on the cantilevered electronic highway signs in-service, and the acceleration responses were measured at six sites over a year. The measured data were analysed with ERA (Eigen-system Realization Algorithm) method to estimate the vibration modes. By clustering the estimated modes with k-means method, 4 commonly excited modes were identified. Furthermore, classification method was developed to determine the order of vibration modes estimated with ERA. The analysis result shows that the natural frequencies of the first and second modes are estimated with the accuracy of 0.003 Hz. It is thought that the accuracy is high enough to detect the changes in the natural frequencies due to the damage of cantilevered highway signs.