Remote Detection of Debonding in FRP-strengthened Concrete Structures Using Acoustic-Laser Technique
Fiber-reinforced polymer (FRP) strengthening and retrofitting of concrete elements, such as beams, columns, slabs, and bridge decks, have become increasingly popular. Nonetheless, rapid and reliable nondestructive testing techniques (NDT) that are capable of remotely assessing in-situintegrity of retrofitted systems are needed. Development of a robust NDT method that provides an accurate and remote assessment of damage and flaws underneath the FRP plates/sheets is required. In this study, a NDT based on an acoustic-laser system is proposed for remote detection of debonding in FRP-strengthened concrete structures. This technique utilizes the difference in dynamic response of the intact and the debonded regions in a FRP-strengthened concrete structure to an acoustic excitation, which is then measured using laser vibrometry. Feasibility and accuracy of the technique were investigated through a series of measurements on laboratory-sized plain, reinforced, and FRP-strengthened concrete specimens. It was shown that the difference in dynamic response could be captured by the acoustic-laser system and is in good agreement with simple calculations.
KeywordsConcrete Debonding FRP Laser vibrometry NDT Remote
This research was supported by the National Science Foundation (NSF) through CMMI Grant No. 0926671. The authors are grateful to the program manager, Dr. Mahendra Singh, for his interest and support for this work. The authors would also like to thank MIT Lincoln Laboratory for providing the experimental equipment and expertise.