Ductile fiber wrapping for seismic retrofit of reinforced concrete columns

Abstract

An experimental study was performed on fiber wrapping to strengthen RC columns with insufficient moment capacity and ductility. In pseudo-seismic test of four columns with a circular cross section, the test variable was fiber type: none, carbon fiber (CF), polyethylene terephthalate (PET), and combined use of CF+PET. PET has high tensile strength and ductility, but very low elastic modulus. While a large area of PET typically needs to be used, the amount of PET actually utilized was about 50% of CF in terms of fiber axial stiffness (E_fA_f). All columns wrapped by CF and/or PET showed significantly improved strengths over the control column (121~143% of control column) while ductility also significantly improved (2.3~3.1 times the control column). Performance of PET was comparable to that of CF in terms of strength and ductility improvement while no sign of fiber rupture was observed at ultimate stage due to excellent ductility intrinsic with PET.