TECHNICAL REPORT DOCUMENTATION PAGE

ABSTRACT

This report presents the use of externally bonded fiber reinforced polymers (FRP) laminates and near surface mounted FRP bars for the flexural strengthening of a concrete bridge. The bridge selected for this project is a three-span simply supported reinforced concrete slab with no transverse steel reinforcement, load posted and located on Martin Spring Outer Road in Phelps County, MO. The original construction combined with the presence of very rigid parapets caused the formation of a wide longitudinal crack which resulted in the slab to behave as two separate elements. The structural behavior was verified implementing the bridge model in a FEM program. The bridge analysis was performed for maximum loads determined in accordance to AASHTO 17th edition. The strengthening scheme was designed in compliance with the ACI 440.2R-02 design guide for externally bonded FRP materials, to avoid further cracking and such that the transverse flexural capacity be higher than the cracking moment. Both FRP strengthening techniques were easily implemented and showed satisfactory performance. An initial load test, to evaluate the structural behavior, was performed prior the strengthening following the AASHTO specifications. The retrofitting of the structure was employed in the summer of 2002, after the major cracks were injected to allow continuity in the cross section. Once the repair work was completed, another load test, identical in procedure to the previous one, was performed to evaluate the efficiency of the strengthening. As a result of this testing, and a report based on this testing by an independent consultant, the load posting of the bridge was removed. A third and last load test was performed in summer 2003, 12 months after the strengthening was finished, to evaluate the long term behavior of the bridge and to investigate whether any type of degradation occurred during the elapsed period. Comparison of the results of the last two load tests showed no significant degradation occurred during the 12 months period. Further, no more cracking was noted in the concrete deck as a result of the strengthening program.

KeyWords 

Bridge, carbon fibers, FEM, fiber reinforced polymers, load test, reinforced concrete, strengthening