Vibration and deformation monitoring of a long-span rigid-frame bridge with distributed long-gauge sensors

Ambient vibration tests and analyses of a long-span rigid-frame bridge were conducted using distributed long-gauge fiber optic sensors. The concept of a long-gauge fiber optic sensor and its merit to reveal local and global structural features are presented. Monitoring of a long-span bridge was performed using long-gauge sensors, and a method to calculate structural deformation distribution from the measured long-gauge strains is proposed, in which shear deformation because of the Timoshenko effect is considered.Modal identification of the studied bridge using the measured long-gauge dynamic strains was also performed, from which strain and displacement mode shapes were identified. These results demonstrate the superiority of long-gauge fiber optic sensors and their successful application to the studied bridge.