High Frequency Deflection Monitoring of Bridges by GPS

The use of GPS for the deflection and deformation monitoring of structures has been under investigation for a number of years. Previous work has shown that GPS not only measures the magnitude of the deflection of the structure, but also it is able to measure the frequency of the movement. Both sets of information are useful for structural engineers when assessing the condition of the structure as well as evaluating whether Finite Element (FE) models of such structures are indeed correct. GPS has the advantage of resulting in an absolute 3-D position, with a very precise corresponding time tag. However, until recently, the maximum data rate was typically 10-20 Hz, meaning that the maximum detectable frequency was about 5-10 Hz. GPS also has the disadvantage of multipath and cycle clips, and the