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A study of bond between fibre reinforced polymer and concrete under quasi static and impact loading Khalighi, Yashar

Abstract

This thesis examines the typical behavior of the interface bond between a selection of FRP treatments and various types of surface preparation on reinforced concrete beams under loading. It also describes an innovative specimen that enables examination of bond properties using a notched beam under a four-point bending test. The thesis also studies the bond between FRP and concrete under impact loading and discusses the strain rate sensitivity of the FRP–concrete bond. Three surface treatment methods (water jetting, sandblasting, and jackhammering), two bonding agents (aromatic isocyanate (ATPRIME®) and vinyl ester), and three FRP systems (sprayed glass fiber reinforced polymer, sprayed carbon fiber reinforced polymer, and glass fiber reinforced polymer wrap) were investigated. The influences of FRP bond length, specimen notch depth, and a wide range of loading rates (creep, quasi-static loading, and impact loading) on bond behavior were also investigated. The notched beam specimen was also used to understand the debonding mechanism under impact loading. An impact setup was successfully developed to measure the bond stress and fracture energy of the FRP–concrete bond. Bond strength values and toughness values were calculated for different surface treatments, FRP application methods, and bonding agents used. The FRP–concrete bond strength was found to be a strain rate sensitive parameter that increases as the strain rate increases. A dynamic improvement factor (DIF) was defined to characterise the influence of different material and strain rate parameters on bond strength. A correlation was found to relate dynamic improvement factor to strain rate for different surface preparation types. An attempt was made to calibrate the energy and traction parameters of the cohesive element in ABAQUS to reproduce the same load displacement behavior as observed in the test from a modeled beam. Using different ABAQUS cohesive zone parameters, the load displacement behavior of the beam was modeled. Even though the load displacement did not completely match the tests, similar magnitudes of displacement and stress were achieved and the debonding mechanism was similar to the reality.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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