Abstract

Abstracted- Reinforced concrete (RC) columns in buildings often need rehabilitation either due to defects in the columns themselves, having to support higher loads than those foreseen in the initial design of the structure, or as the result of ageing or accidental damage. The use of steel caging for this purpose is now a common practice in many countries throughout the world. In this paper, experimental works is presented to investigate the behavior of of reinforced concrete columns strengthened externally with steel jacket under axial loads. This experimental work comprises of twelve square reinforced concrete columns with same cross section of (120x120)mm and height of 1000mm. These columns divided to four groups, the first group (includes three columns) represents the control samples i.e without any type of strengthening, second group (includes three columns) strengthened by various sizes of four vertical steel angles at column corners linked by horizontal battens, third group (includes three columns) strengthened by constant sizes of four vertical steel angles at column corners linked by various sizes of steel plates at top and bottom of columns, while fourth group (includes three columns) strengthened by constant sizes of four vertical steel angles at column corners linked by (various sizes of steel plates at top and bottom of columns besides horizontal battens).The results show that the rehabilitation technique (strengthening) of R.C. columns by using external steel jacket can increase the ultimate load from (42.2-121.7)%. Abstracted- Reinforced concrete (RC) columns in buildings often need rehabilitation either due to defects in the columns themselves, having to support higher loads than those foreseen in the initial design of the structure, or as the result of ageing or accidental damage. The use of steel caging for this purpose is now a common practice in many countries throughout the world. In this paper, experimental works is presented to investigate the behavior of of reinforced concrete columns strengthened externally with steel jacket under axial loads. This experimental work comprises of twelve square reinforced concrete columns with same cross section of (120x120)mm and height of 1000mm. These columns divided to four groups, the first group (includes three columns) represents the control samples i.e without any type of strengthening, second group (includes three columns) strengthened by various sizes of four vertical steel angles at column corners linked by horizontal battens, third group (includes three columns) strengthened by constant sizes of four vertical steel angles at column corners linked by various sizes of steel plates at top and bottom of columns, while fourth group (includes three columns) strengthened by constant sizes of four vertical steel angles at column corners linked by (various sizes of steel plates at top and bottom of columns besides horizontal battens).The results show that the rehabilitation technique (strengthening) of R.C. columns by using external steel jacket can increase the ultimate load from (42.2-121.7)%.