Monitoring Bridge Scour Using Fiber Optic Sensors. Tech Summary.

摘要

It is well known that scour is one of the major causes of bridge failures. In the last 30 years, more than 1,000 bridges collapsed in the US and about 60% of the failures are related to the scour of bridge’s foundations. Due to the difficulty in inspecting bridge scour, scour-induced failures tend to occur suddenly without prior warning or signs of distress to the structures. Owing to the threat of hurricane-induced flooding and the fact that there are a significant number of coastal and river/bayou bridges in Louisiana, a more reliable inspection and monitoring procedure for bridge scour is needed. Fiber Optic Sensors (FOSs) have become increasingly popular in long-term monitoring of structures, especially in harsh environments. The FOSs’ major unique benefits related to this project are: corrosion-resistant and long-term stability that make it possible to be embedded in soil/foundations and submerged in water; distributed sensing and multiplexing capabilities that make it possible to install a series of sensors along a single cable to collect information along the depth of the foundation; small size and light weight with little disturbance to the structure and soil; immunity to electromagnetic/radio frequency interference, etc. FOS system, particularly fiber Bragg Grating (FBG) sensors, has been explored for this application by using it to measure strain and other related information so that the scour situation of bridges can be either directly monitored or derived. This project will help Louisiana develop the required expertise for the field applications of fiber optic sensors. The success of this research project will reap great economic benefits and may largely impact the practice of bridge maintenance in Louisiana. There is also potential for this project to develop and test equipment that can be used for future scour monitoring. The ultimate objective will be to develop more efficient strategies to mitigate the deficiencies of bridges.