Structural Monitoring of Cable-Stayed Bridge: Analysis of GPS versus Modeled Deflections

In this study global positioning system (GPS) technology is used to monitor the structural movement of a cable-stayed bridge over the River Tamar in northern Tasmania, Australia. Observed displacements are compared with predicted deflections derived from modeling undertaken with the Space Gass structural analysis software suite. Results show that GPS is successful in quantifying both thermally induced bridge displacements and high frequency transient motion caused by vehicle loading. GPS-derived estimates of the bridge’s short-term dynamic motion correlate well with the predicted model response, providing the ability to verify the model and pose potential improvements to the model configuration. Deflection signatures from GPS show typical displacements on the main span of $54\pm 3.5\mathrm{mm}$ in height, with corresponding longitudinal displacements on the tower structure of $17\pm 2\mathrm{mm}$ . Displacement of the bridge caused by thermal variations is also clearly evident in the data and correlates well with additional external measurements. GPS is a valuable observational tool for monitoring structures and provides a powerful analysis tool for verification and/or improvement of structural design and modeling.