AN EXPERIMENTAL STUDY ON THE SEISMIC RETROFIT TECHNIQUE FOR RC COLUMNS CONFINED WITH PC BAR PRESTRESSING AS EXTERNAL HOOPS

Abstract

By paying attention to the fact that the transverse confinement of concrete is very useful in order to improve ductility for RC members, a new seismic retrofit technique is proposed as one of improving ductility for RC columns in this paper. The technique is an active confinement by PC bar prestressing as external hoops. These column specimens with shear span to depth ratio M/(VD)=1.5 are modeled upon the school buildings designed by the old seismic design standards before 1971 in Japan. These RC column specimens were tested under the combination of cyclic lateral forces and constant axial load. As a result, the retrofit column specimens illustrated excellent seismic performance through experimental tests, even if the RC column test specimens were likely to happen shear failure.