Prestressed concrete (PC) C-channel and cored slab bridges have been in-service in North Carolina for more than 40 years. Increasing numbers of these bridges have deteriorated due to corrosion of the prestressing strands, overload traffic, and natural aging, to the extent that they require load-posting or closure before superstructure replacement can be scheduled.
The research program presented herein developed a rapid and easy-to-install repair using a prestressed mechanically-fastened fiber-reinforced polymer (MF-FRP) system. It has been shown through full-scale experimental testing that the system improves the response of repaired deteriorated bridge beams such that inventory and operating load limits can be increased by restoring the lost prestress from the corroded steel strands.
This system can either be installed on the inside faces of Prestressed Concrete Channel Beam legs or on the underside of Prestressed Cored Slab units as seen below
Critical components of the MF-FRP repair system were developed through a series of small-scale tests to optimize the efficiency and installation of the system. The long-term behavior of the MF-FRP system, including sustained load and fatigue effects, were also studied to help quantify the expected service life of the repair. A layered-sectional analysis approach (LSA) was developed and shown to give a good prediction of the full flexural behavior of repaired C-channel beams and cored slabs. In addition to flexural deterioration, deterioration at the end region of C-channel beams, which was recently observed on-site, was also considered in the design of the MF-FRP system. A shear strengthening plate was designed to integrate with the original flexural MF-FRP repair system at the end regions. Full-scale C-channel beams were tested to study the member shear behavior using the flexural/shear MF-FRP repair system.
Finally, a field application using the designed MF-FRP system was conducted on an in-service deteriorated C-channel bridge, along with instrumentation to enable long-term monitoring. The repair system remains in good and stable condition after being in-service for more than one year.
