Flexural analysis of RC beam strengthened by partially de-bonded NSM FRP strip

Abstract

With regards to the Near Surface-Mounted Retrofit method using FRP in reinforced concrete flexural members, uniform deformation occurs as a whole in de-bonded FRP in the case of partial bonding at both ends and de-bonding in the central part. This leads to relief of rapid increase of the deformation at a particular position in the case of full bonding, which is effective in relieving brittle failure phenomena. In this manner, the analytical method to describe the flexural behavior of reinforced concrete beams strengthened with Near Surface-Mounted FRP strips is studied in this paper by making recourse to the analytical approach. Especially in order to improve the structural deformation capacity, the characteristics of anchorage part and de-bonded part were taken into account in the analysis conducted with respect to the beam with partially de-bonded FRP in the central part. In this regard, an effective method for flexural analysis of the partially de-bonded FRP strip is proposed in the present study by reflecting the bond behavior of NSM FRP strip in the flexural model based on the stress transfer mechanism between NSM FRP strip and concrete. From the assumption that the strain of FRP at the de-bonded region is uniform and the consideration of anchorage failure patterns, it was found that the flexural behavior of the reinforced concrete beam strengthened by partially de-bonded NSM FRP strip can be suitably described to explain the ductile behavior due to the de-bonding. (C) 2016 Elsevier Ltd. All rights reserved.