An investigation into multi-scale periodic dynamic deformation monitoring of bridges through integrated spaceborne and ground-based InSAR

Monitoring the structural deformation of bridge with high precision during the operation process is crucial for assessing its health. This study proposes a practical strategy for jointly measuring multi-scale periodic dynamic deformation in bridges using both spaceborne and ground-based Interferometric Synthetic Aperture Radar (InSAR) technologies. The proposed strategy involves extracting seasonal periodic deformation by applying thermal expansion components with spaceborne Persistent Scatterer InSAR (PS-InSAR) and capturing daily periodic deformation using a two-stage atmospheric phase screen compensation ground-based InSAR method. This study focuses on a double-tower cable-stayed and rigid frame system bridge to investigate the spatiotemporal evolution of bridge multi-scale periodic dynamic deformation patterns. The monitoring results indicate that the geometric state and deformation pattern of the bridge remained stable, exhibiting significant seasonal and daily dynamic deformations that were either positively or negatively correlated with temperature changes. Seasonal periodic deformation captured by spaceborne InSAR showed maximum displacements near expansion joints, while tower deformation remained constrained within ±5 mm. Daily periodic deformation captured by ground-based InSAR revealed significant displacements at the bridge tower top, contrasting with minimal deformation of ±2 mm near fixed bearings. These deformations exhibited significant correlations with temperature changes. Both the deformation trend and magnitude confirmed to the computational results of the bridge structure design.