The coefficient of transverse thermal expansion of glass fibre reinforced polymer (FRP) barscan be substantially higher than that of concrete. Because of this thermal incompatibility, a rise oftemperature can result in tensile stresses and radial cracking of the concrete surrounding the bars. Suchcracking weakens the bond between the FRP bars and the concrete and may propagate to the outersurface and cause splitting of the concrete cover. This paper presents the results of experimentsconducted to investigate the above phenomenon. Concrete cylinders concentrically reinforced with glassFRP bars of different types and diameters were subjected to a uniform rise of temperature. The values oftemperature at splitting of the concrete cover were recorded and were found to compare favourably wellwith analytical results obtained from a nonlinear finite element model of the test cylinders. The finiteelement model was then used in a parametric study of the main parameters that affect cracking of theconcrete cover due to transverse expansion of glass FRP bars under temperature rise. The parametersinvestigated include the magnitudes of the coefficient of transverse thermal expansion and the transversemodulus of elasticity of the FRP bars, the concrete strength, and the ratio of concrete cover-to-bardiameter. Based on this study, design charts have been developed to determine the minimum ratio ofconcrete cover-to-bar diameter necessary to avoid splitting. These charts have been adopted by ISISCanada in its Design Manual No. 3: Reinforcing Concrete Structures with Fibre Reinforced Polymers.
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