Strengthening and Evaluation of Reinforced Concrete Beams for Flexure by Using External Steel Reinforcements

The most implementable and favorable technique, used for the flexural strengthening of reinforced concrete (RC) beams is the attachment of external steel members. Attachment of external steel sections or fiber reinforced polymers is considered as a common technique used for the enhancement of flexural capacity of the existing structural elements. To investigate and evaluate the flexural capacity of reinforced concrete beams, strengthened with external steel bars, a research study was carried out and is presented in this paper. Three reinforced concrete beams reinforced with minimum reinforcement ratio were constructed and tested. Two beams were strengthened by attaching external steel bars with bottom layer of shear reinforcement and one specimen without external steel bars was tested as control sample. The area of reinforcement to be provided as external steel bars was calculated on the basis of maximum steel ratio as per the ACI- (318-08) 10.3.5. Welding was used for the attachment of the external steel bars to the existing shear reinforcement. All the three beams were tested in positive bending under third point loading as per the ASTM C78/C78M-10. Test result shows that great enhancement in strength capacity and better distribution of cracks may be achieved by using this technique of flexural strengthening of beam.