Retrofitting nonseismically detailed exterior beam–column joints using concrete covers together with CFRP jacket

• Retrofitting exterior beam–column joints with CFRP and concrete covers.
• Modify the columns of beam–column joints before wrapping with CFRP.
• The glued concrete covers work well together with the existing concrete.
• The application of CFRP on the modified circular sections improved its effectiveness.

This paper introduces a new method for retrofitting reinforced concrete (RC) exterior beamcolumn T joints, using segmental circular concrete covers together with Carbon Fibre Reinforced Polymer (CFRP). Two RC T connections without transverse reinforcement at the joints were cast and tested. The first connection (Strengthened specimen, TS) was glued with the concrete covers around the column at the joint area to modify it from a square to a circular section and then it was wrapped with CFRP to strengthen its capacity. A load was first applied on the second connection (Repaired specimen, TR) to cause a serious failure then it was repaired. The repair scheme of the second connection was identical to the first connection. Results of testing the two connections have shown that the performances of both the strengthened and the repaired connections were improved significantly. The glued concrete covers worked well with the existing concrete to resist shear load. Moreover, the wrap on the modified circular sections helped in increasing the effectiveness of CFRP by increasing the confinement effect on the concrete and reduce the possibility of debonding of CFRP at the joints.