1 SHEAR CAPACITY OF REINFORCED CONCRETE COLUMNS RETROFITTED WITH VERY FLEXIBLE FIBER REINFORCED POLYMER WITH VERY LOW YOUNG’S MODULUS

FRP with low Young’s modulus (SoftFRP) was developed in the late 1990’s and early 2000’s. Polyketone fiber is a kind of new material of FRP with low Young’s modulus and made from carbon monoxide and ethylene. And compared with aramid fiber, its material cost is lower. To investigate the improvement of shear strength of column wrapped with this kind of FRP sheets, four specimens among which one was unstrengthened and three specimens were wrapped by different amount of FRP sheets which provided the equivalent shear reinforcement ratio was 0.04%, 0.08 % and 0.12 % were tested. All specimens were tested under lateral reversal cyclic loading and a constant axial load. It is found that the shear strength of the RC column effectively increased with strengthening FRP sheet. And it prevents the sudden brittle fracture of the column because of the confinement of FRP sheets with large deformation capacity. The shear resistance of the FRP sheet becomes effective after the yield of shear reinforcement, and the strain of FRP sheet becomes large. The shear contribution of the FRP sheets could be explained by truss-arch shear resisting mechanism