Application of FRP laminates for strengthening of a reinforced-concrete T-beam bridge structure

This paper describes application of fiber-reinforced polymer (FRP) composite laminates to strengthen an aging reinforced-concrete T-beam bridge in South Troy, Rensselaer County, New York. Leakage at the end joints of this single-span structure led to substantial moisture and salt infiltration in the bridge superstructure. Presence of efflorescence was observed, and freeze-thaw cracking and concrete delamination at some locations on the beams were noted. Concerns about integrity of the steel reinforcing and overall safety of the bridge were raised. These concerns were heightened by the absence of any documents pertaining to the bridge design, such as rebar size, steel type, concrete strength, and design loads. Thus, a decision was made to strengthen the bridge using bonded FRP-laminates. Load tests were conducted to evaluate effectiveness of the strengthening system and investigate its effect on structural behavior, and tests results were compared with those obtained using classical analysis.