Online Monitoring of Flexural Damage Index of a Cable‐Stayed Bridge

Abstract

This work introduces a recent application of the online nondestructive damage assessment system into a cable-stayed bridge. A set of ambient modal parameters are automatically extracted every 20 minutes using real-time signal data collected from a total of 26 accelerometers attached on the deck plate of the bridge. Then, a set of modal flexibilities are reconstructed by the combination of the extracted modal parameters with the approximated modal mass of the girder. Next, the curvature of the modal flexibility is approximated by a central difference formula. Finally, the set of flexural damage index equations is constructed by comparing the modal curvature of the damaged state to that of the undamaged state. Solving the overdetermined flexural damage index equations, the desired damage index is finally quantified. The resulting index clearly indicates the location and severity of the potential structural damage on the girder. Based on the overall performance of the implemented health monitoring system, the bridge operator’s damage index control criteria are set to ±20% of the undamaged state.

Damage Identification Based on Adding Mass for Liquid–Solid Coupling Structures

“…where M p is the attached fluid mass matrix, which represents the additional pressure of fluid caused by the vibration acceleration of the structure on the contact surface. Its specific calculation formula can be found in Equations (6) and (7). The detailed derivation of the attached fluid mass (see Equation (6)) is available in Ref.…”

“…To ensure the safety of structures, structural health monitoring (SHM) became a very important research topic and many effective SHM methods were developed [1][2][3][4][5]. Damage identification methods [6][7][8][9][10][11][12] can provide critical theoretical foundations for SHM. Because of the rapid development of sensor techniques and experimental protocols, damage identification methods, based on the structural dynamic response, have been widely studied and applied, including the time-domain response-based methods and the modal response-based methods.…”