Damage-Identification Method for Bridge Structures Based on Displacement Influence Line and Wavelet Packet Analysis

This paper proposes a method of identifying damage to bridge structures based on the principles of displacement influence line and wavelet packet transform. Three damage identification indicators were constructed, including the deviation of displacement influence line (DDIL), the deviation curvature of displacement influence line (DCDIL), and the relative energy rate of wavelet packet energy spectrum (RES). Taking a continuous beam bridge as an example, a finite element model is established to analyze the differences in using three indicators to locate the structural damage position, and to explore the effects of factors such as damage degree, damage location, dynamic response type, and bidirectional traffic on the identification effect. Next, the Zhengzhou Taohuayu Yellow River Bridge is taken as a practical case for verification analysis, and the anti-interference ability and sensitivity of the RES damage indicator are discussed under the interference of noise factors. The results demonstrate that the three identification indicators have excellent performance in identifying bridge structure damage. Compared to the DDIL, the DCDIL shows a more obvious mutation at the damage location, while the RES curve improves the problem of poor identification effect at locations far from the midspan of the bridge by requiring response information from multiple points of the bridge. The RES curve, which was constructed using displacement as the input parameter, exhibits the best comprehensive identification effect. Additionally, it maintains its robustness even when subjected to the interference of bidirectional traffic and noise.