Repair and FRP strengthening of earthquake-damaged RC shallow beam-column joints

Abstract

Three earthquake-resistant wide beam-column joint specimens (one interior, and two exterior) which developed beam plastic hinging mechanism and beam flexural failure under large drift reversals were repaired and FRP strengthened for restoring their structural function. The repair and strengthening technique consisted of: (i) sealing the major flexural cracks that developed within the beam plastic hinge region using epoxy injection; (ii) adding carbon fiber-reinforced polymer (CFRP) reinforcement at the top and bottom faces of the beam to control the growth of the flexural cracks, boost up the beam negative and positive flexural capacities and at the same time compensate in part for the loss in the joint lateral stiffness; and (iii) providing CFRP jacket at the potential hinging regions of the columns for confining the concrete and enhancing the bond capacity of the spliced reinforcement. The effectiveness of the upgrading technique is demonstrated by comparing the performance of the upgraded joints when subjected to lateral cyclic loading against the performance of the same joints before damage. With its simplicity in application, the upgrading technique succeeded in bringing the damaged joints back into service conditions and in restoring their flexural stiffness under lateral load which degraded due to large drift reversals.