Strengthening of reinforced concrete column in the existing building is necessary, as the failure of columns collapses the whole structure. As a retrofitting technique, the use of steel bars in the column is almost un-covered in the literature. This project focuses on the effectiveness of the technique of providing steel bars externally in order to strengthen the column. Two types of strengthening is carried out in the columns by removing the cover of the reinforced concrete column. Type1 column is strengthened by welding the steel bars at the corners of the stirrups along the main reinforcement and Type2 is by welding the steel bars at the centres of the stirrups along the main reinforcement. The experimental investigation showed that the load bearing capacity of the columns is improved to 25% and 35% under axial compression and the technique is found to be effective. An analytical study is carried out to analyse the deflection behaviour of the strengthened columns. Also, a theoretical study is conducted and the results are compared with the experimental work which showed an increase in percentage of strength.

Keywords : Retrofitingt; steel bars; welding.