Shear capacity strengthening using high fracturing strain fiber materials

This paper presents the experimental findings of cyclic loading test of two shear strength deficient reinforced concrete pier which were strengthened by external wrapping using continuous fiber sheet with PET (Polyethylene Terephthalate), a large fracturing strain material. These specimens were tested under reversed horizontal loading to represent earthquake excitation. The key mechanical properties of these materials are low tensile modulus of elasticity and large fracturing strain. The elastic modulus and fracture strain of PET are 10GPa and 13.8%, respectively. The objective of this experiment is to get the optimum contribution of the PET to shear capacity and ductility enhancement. The experimental results on the hysteretic response of test piers, ductility analysis and shear deformation of the specimens are presented. The experimental results are compared with results from a specimen strengthened using Carbon fiber and an unstrengthened specimen. In contrast to piers retrofitted using the carbon fiber materials, experimental results showed that piers strengthened with PET fiber is less likely to rupture before the pre-defined ultimate state is reached. In a specimen rupture of steel tie reinforcement was found while no rupture was found with PET fiber sheet. The existing formulae for shear strength prediction of members with carbon and aramid sheet according to JSCE code underestimates shear strength of members with PET fiber sheet.