Output-only modal identification of a reinforced concrete bridge from radar-based measurements

This paper addresses the application of a non-contact vibrometer, designed for dynamic testing and monitoring of large structures. The new system consists of a radar sensor apt to simultaneously measure the (static or dynamic) displacement of several points of a structure with high sensitivity.In this paper, the sensor and its major characteristics are first described; subsequently, application to the measurement of ambient vibration response of a concrete bridge is summarized. The correspondence between the signals simultaneously acquired from radar and accelerometers was extensively investigated; furthermore, resonant frequencies and mode shapes identified with the radar system are compared to the corresponding quantities measured with conventional sensors.