The evaluation of structural performance for R/C beams strengthened by NSM using CFRP plate

Abstract

The near surface mounted (NSM) FRP strengthening method has been conventionally applied for strengthening the deteriorated concrete structures. The NSM strengthening method, however, has been issued with the problem of limitation of the cutting depth which is usually considered as concrete cover depth. This may be related with degradation of bonding performance in long-term service state. To improve the debonding problem, in this study, the Stirrup partial-Cutting NSM (SCNSM) strengthening method using CFRP plate was newly developed. SCNSM strengthening method can be effectively applied to the deteriorated concrete structure without any troubles of insufficient cutting depth. To experimentally verify the structural behavior, the flexural test of the concrete beam by using the SCNSM strengthening method was conducted with the test variable as the strengthening length. In the result of the test, the NSM and SCNSM strengthened specimen showed similar structural behavior with load-deflection, mode of failure. Additionally, there was no apparent structural degradation by the Stirrup partial-Cutting. Consequently, it was evaluated that the SCNSM strengthening method can be useful for seriously damaged concrete structures that are hard to apply the conventional NSM strengthening method for increasing the structural capacity.