Modified split disk test for characterization of FRP composites

Abstract

Fiber reinforced polymers (FRP) are used to wrap reinforced concrete (RC) elements to increase their load carrying capacity and, in such applications, the mode of failure of the retrofitted element is usually governed by the rupture of the FRP when it reaches its ultimate strain. This paper reports the split disk test (as in ASTM D2290) modified to characterize the stress-strain behaviour of FRP using a simple specimen preparation methodology. The results obtained from the modified split-disk tests on glass and carbon-FRP composites are compared with those from uniaxial FRP coupon tests. It is found that the elastic modulus obtained from both the methods are similar but the ultimate strains and the tensile strengths from the split-disk tests are lower. To compare the split disk ultimate strains, FRP confined concrete cylinders of 150 mm in diameter and 300 mm in height were prepared and tested under uniaxial compression, after wrapping with carbon and glass FRP sheets. The average ultimate strains of FRP with split-disk test are lower than the ultimate hoop strains observed in FRP-confined cylindrical specimens. Consequently, strain efficiency factors have been determined for application in design.