STRENGTHENING AND REHABILITATION OF REINFORCEMENT CONCRETE SQUARE COLUMNS CONFINED WITH EXTERNAL STEEL COLLARS

Strengthening and rehabilitation by confinement technique of reinforced concrete columns was investigated. The columns were confined by external steel collars. Behavior and failure load of columns were experimentally investigated. Results show that Confinement in concrete column has improved its strength and ductility. Effect of confined area, size of collar and compressive strength of concrete on strengthening was investigated .Confined area had significant effect on the failure load for strengthened specimens and had more effective on the failure load for repaired specimens. The confinment had clearer effect with low compressive strength of concrete. The result show an increase in ultimate axial load reach to (12.36 – 56.04%) for strengthening columns and (47.5 –96.7%) for reaparing columns.