Recently
the authors have developed a jacketing method with fiber sheet whose fracturing
strain is higher and
stiffness is lower than those of commonly used fibers
namely carbon aramid and glass. The fiber is Polyethylene Terephthalate (PET)
and Polyethylene Naphthalate (PEN). In this paper results from a series of
experiments on
ductility and shear strength
enhancement are presented. Fifteen
specimens, modelled after a typical bridge pier, with PET and PEN sheet
jacketing were tested under a reversed cyclic loading until the ultimate
ductility was attained. The stiffness of PET and PEN sheet is smaller than that
of carbon sheet to achieve a similar ultimate ductility. Two specimens tested
for shear strength enhancement showed a higher shear strength and more ductile
manner than a companion specimen with carbon fiber sheets. A good control of
shear deformation by the un-fractured sheet is a primary reason to enhance the
ductility and shear strength which cannot be predicted by the existing formula
derived from results of tests with carbon and aramid fibers. Due to its good
features and lower cost, the jacketing with PET and PEN sheet is adopted as a
seismic retrofitting method for railway structures in Japan.