STUDY ON BEHAVIOR OF FRP SHEET DEBONDING AS FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAM

Strengthening of structures with Glass Fiber Reinforced Polymer (GFRP) sheets is an effective method to increase the capacity of the structures. This GFRP material has a tensile strength of up to 3240 Mpa so that when used in a concrete structure it can play an effective role in enhancing the tensile strength of the structure elements. However, the release of the GFRP sheet from the concrete surface (debonding) is the cause of the non-optimal ability of the strengthened beam. This paper is focused on the study of the debonding behavior of GFRP sheet patched on the tensile section of a concrete beam. The specimen consisted of three control beams and nine strengthened beams with various bond area of GFRP sheet. The observed data were the maximum load, deflection, concrete strain and GFRP strain. The results indicated that the flexural capacity of the strengthened beam increased up to 10.85 % compared to the normal beam. The bonding length of the GFRP sheets has no significant effect on the load capacity. Moreover, all the strengthened beams failed by the debonding of the bonded sheet, which was initiated by local debonding on the critical bonding stress location.