Damage detection of a bridge model after simulated ground motion

Vibration-based damage detection techniques offer interesting opportunities for Structural Health Monitoring of strategic structures and infrastructures, such as bridges, and they foster the shift from time-based maintenance to condition-based maintenance. However, effective vibration-based damage detection requires accurate estimates of the modal parameters of the monitored structure automatically obtained from the analysis of the operational response of the structure. In the present paper, the opportunities and limitations of automated output-only modal identification and modal-based damage detection for bridges are briefly reviewed. The results of an extensive experimental campaign on a scaled bridge model are then illustrated. The objective of the experimental tests was twofold. The dynamic response of the structure has been experimentally characterized for different support conditions (simply supported, with seismic isolation devices). After this first stage of analysis, an input ground motion has been applied by means of a couple of asynchronous shaking tables. As a result of the seismic input, the structure without seismic isolation devices was damaged. The effect of damage on the modal properties and the possibility to detect damage by means of selected damage features are discussed on the basis of the obtained experimental results