Analytical Damping Evaluation Complementary to Experimental Structural Health Monitoring of Bridges

Structural health monitoring (SHM) of bridges by visual inspection is not necessarily reliable as many damages are not discovered during the periodic inspection of bridges. A technique to assist in visual inspection is vibration-based SHM. It is believed that structural damages lead to changes in stiffness and damping properties, and change the dynamic characteristics of structures, such as natural frequency, mode shape, and modal damping ratio. Although changes in the modal damping ratio can be used as damage indicators in the field of vibration-based SHM, the method's accuracy remains concerning. This study investigated the analytical modal damping evaluation as a complementary method to the experimental SHM of bridges. An energy-based damping model was introduced to estimate the damping parameters of a steel arch bridge, such as the equivalent loss factors of structural components, and the modal damping ratios of the bridge were then analytically evaluated using the damping parameters. The results confirmed that the proposed methodology can identify the damping sources in steel bridges and their contributions to each modal damping ratio, and complements the experimental SHM of bridges. (c) 2014 American Society of Civil Engineers.