| The structures constructed before 1971 have suffered severe damages during earthquakes. Investigation has demonstrated that concrete columns with inadequate confinement significantly contributed to the collapse of these structures. As a result, major efforts were directed towards developing and applying retrofitting strategies to upgrade seismic performance of such columns.; This research evaluates the effectiveness of strengthening deficient and repairing damaged square columns with GFRP sheets. Eight columns with cross-section of 305 x 305 mm were tested under simulated earthquake loads. Three additional columns with identical cross section were tested under pure axial compression.; Test results reveal that confinement through GFRP sheets can significantly enhance ductility, energy dissipation ability, and moment capacity of deficient square columns. Higher ductility and improved seismic performance can also be achieved by retrofitting damaged columns with GFRP jackets. However, overall ductile performance depends upon the extent of damage sustained by the specimens before wrapping. |
