retrofitting of reinforced concrete columns using steel and concrete jacketing tchnique

retrofitting structures is an important issue. structural weakness may be due to changes in design codes or defects in implementation. adding structural floors to the existing structures may also lead to the need for strengthening and retrofitting. retrofitting is possible before the earthquake or may take place as rehabilitation of damaged members after earthquake. elements such as columns in buildings are vulnerable to earthquakes. increasing the ductility and load bearing capacity of reinforced concrete columns can be effective in strengthening the entire structures. in recent years several methods for repairing or strengthening the columns have been presented and several theories have been proposed about increasing their load bearing capacity. one of these methods is using reinforced concerte or steel profile jacketing technique. retrofitting methods also should be applicable and cost effective. this method of retrofitting on weak or damaged columns improves the axial and shear load bearing capacity and increases the ductility. in this research 12 column specimens in small scales were prepared in laboratory and retrofitted using jacketing technique. load bearing capacity of the specimens before and after retrofitting were calculated and compared. finally advantages and disadvantages of this method were investigated using experimental test results.