Monitoring bridge scour using fiber optic sensors : [tech summary].

PDFBriefState Project No. 736-99-1573LTRC Project No. 08\uc2\ubf2STBridge foundationsScourStructural health monitoringFiber opticsSensorsInstrumentationLaboratory testsLouisianaLouisiana Transportation Research CenterCai, Steve C. S.Louisiana Transportation Research CenterUS Transportation CollectionIt 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 inthe US and about 60% of the failures are related to the scour of bridge\ue2\u20ac\u2122s foundations. Due to the difficulty in inspecting bridgescour, scour-induced failures tend to occur suddenly without prior warning or signs of distress to the structures. Owing to thethreat of hurricane-induced flooding and the fact that there are a significant number of coastal and river/bayou bridges inLouisiana, 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 harshenvironments. The FOSs\ue2\u20ac\u2122 major unique benefits related to this project are: corrosion-resistant and long-term stability that makeit possible to be embedded in soil/foundations and submerged in water; distributed sensing and multiplexing capabilities thatmake it possible to install a series of sensors along a single cable to collect information along the depth of the foundation; smallsize 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 measurestrain and other related information so that the scour situation of bridges can be either directlymonitored or derived.This project will help Louisiana develop the required expertise for the field applications offiber optic sensors. The success of this research project will reap great economic benefits andmay largely impact the practice of bridge maintenance in Louisiana. There is also potential forthis project to develop and test equipment that can be used for future scour monitoring. Theultimate objective will be to develop more efficient strategies to mitigate the deficiencies ofbridges