Prestressed MF-FRP: Experimental Study of Rapid Retrofit Solution for Deteriorated Prestressed C-Channel Beams

This paper presents design and installation details and full-scale test results for a prestressed mechanically fastened fiber-reinforced polymer (MF-FRP) retrofit solution that restores the original operating and inventory rating of prestressed concrete C-channel bridge superstructures with prestress losses due to concrete deterioration and steel corrosion. A retrofit solution that can be installed rapidly and immediately restores prestress losses is desired to minimize impacts on commerce, public transportation, and emergency services. Six 9.41-m (30-ft) long C-channel beams were tested for three-point bending to failure. The results of the experimental study indicate that the MF-FRP retrofit is capable of immediately restoring deteriorated C-channel beams with a 36% reduction in capacity from the original operating and inventory ratings. In this study, the reduction in the capacity of the C-channel beams was induced in the lab by cutting the bottom strand of each stem of the C-channel beam to simulate total prestress losses at the point of maximum internal moment. Further, the results of the experimental study indicate that the examined MF-FRP retrofit solution can be installed in 4.1 labor hours per retrofitted C-channel beam. Therefore, a four-worker DOT maintenance crew can install the retrofit on up to seven beams in a single eight-hour workday. A layered sectional analysis can be used to predict the flexural capacity of retrofitted C-channel beams with very good accuracy.