A new method of strengthening reinforced concrete columns against axial failure was developed and verified through seismic tests. The purpose of the strengthening was specially focused on the maintenance of axial load capacity to prevent total collapse of a structure under very large lateral deformation of the columns. A total of eight specimens, which represents reinforced concrete columns designed by the old building code of Japan or Turkey, were tested under constant gravity load and cyclic lateral load. Some of the columns were strengthened using polyester sheet by which the cost of retrofit would remarkably be reduced from existing technology. The columns strengthened by the new method could maintain the relatively high gravity load until more than ten percent inter-story drift, which was ten times or more than that of the specimen without strengthening. A series of axial tests on concrete prisms and cubes confined with the sheet in various types were also tested, based on which the hysteresis relations and axial load resistance mechanism of the columns were interpreted. It may be concluded from the tests and analysis that the new method is efficient, effective, economical and ready for use in seismic retrofit of existing buildings.
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