Externally Bonded FRP Composites of RC Structures

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9506736 Nanni The objective of this project is to provide the engineering science necessary for the implementation of externally bonded FRP reinforcement for the repair of concrete structures, except for the case of members subjected to compression where enhancement of strength and ductility is the result of lateral confinement of concrete. The material forms of interest are highly flexible sheets made of dry fibers or prepregs that can be adhered to a concrete surface after minimum surface preparation by means of a polymeric resin. The fibers are high-strength and high-modulus such as carbon and aramid. The methodology of the project consists of an experimental and analytical study based primarily on tensile reinforced concrete specimens. Tests are conducted under quasi-static conditions after mechanical conditioning (repeated and sustained loading) and environmental conditioning (thermal cycling and exposure to aggressive environments). The experimental program is necessary to quantify the effects of externally bonded FRP reinforcement on concrete resistance to cracking and to assess long-term strengthening performance. A part of the durability study is to determine whether the presence of FRP reinforcement promotes/inhibits degradation of steel reinforcement in concrete (i.e., galvanic corrosion when FRP is made of conductive fibers). Various material forms, conditions at time of repair and preparation conditions are investigated. Primary measurements include load, strain, interfacial delamination, crack opening, and electrical conductivity. The project is conducted with the collaboration of the manufacturing and construction industry in the intent of securing suitable materials and of using field applications as a test bed for laboratory findings and verification of modeling. ***