Flexural strengthening of reinforced concrete (RC) beams using externally bonded fiber reinforced polymer (FRP) sheet is a popular application nowadays. In this application, the FRP to concrete bond interface is typically exposed to a mixed-mode loading condition at the vicinity of a critical flexural/shear crack, which includes a pull-out action parallel to the interface and introduced by the opening displacement of the flexural/shear crack together with a push-off action perpendicular to the interface and introduced by the shear sliding displacement of the flexural/shear crack. This paper presents an experimental program to evaluate the fracture properties of the FRP to concrete interface under the coupled pull-out (mode II) and push-off (mode I) loading condition. An analytical model was developed to evaluate the mode I and mode II strain energy release rates and the corresponding fracture mechanisms of the FRP to concrete interface under a pure bending action, a pure dowel action, and the coupled action of both, respectively. The reliability of the proposed analytical model was verified in comparison with the experimental results.
ACI committee 440. 2R. (2002). Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures, American Concrete Institute, Farmington Hills, MI.
2.
BuyukozturkO. and HearingB. (1998). “Fracture behavior of precracked concrete beams retrofitting with FRP”, Journal of Composites for Construction, ASCE, Vol. 2, No. 3, pp. 138–144.
3.
ChenJ.F. and TengJ.G. (2001). “Anchorage strength models for FRP and steel plate bonded to concrete”, Journal of Structural Engineering, ASCE, Vol. 127, No. 7, pp. 103–112.
4.
ChenJ.F.YuanH. and TengJ.G. (2007). “Debonding failure along a softening FRP-to-concrete interface between two adjacent cracks in concrete members”, Engineering Structures, Vol. 29, No. 2, pp. 259–270.
5.
DaiJ.G.UedaT.OzakiH. and SatoY. (2003). “Experimental study on the mixed-mode fracture of FRP sheet-concrete interfaces”, Proceedings of JCI International Symposium: Latest Achievement in Technology and Research on Retrofitting Concrete Structures-Interface Mechanics and Structural Performance, Kyoto, Japan, pp. 113–120.
6.
DaiJ.G.UedaT.SatoY. and JaqinH. (2004). “Dowel resistances of bond interfaces between FRP sheets and concrete”, FRP Composites in Civil Engineering – CICE 2004, Proceedings of the Second International Conference on FRP Composites in Civil Engineering – CICE 2004, Adelaide, Australia, pp. 371–380.
7.
DaiJ.G.UedaT. and SatoY. (2007). “Bonding characteristics of fiber reinforced polymer sheet-concrete interfaces under dowel load”, Journal of Composites for Construction, ASCE, Vol. 11, No. 2, pp. 138–149.
8.
DaiJ.G.HarriesK.A. and YokotaH. (2008). “A critical steel yielding length model for predicting intermediate crack-induced debonding in FRP-strengthened RC members”, Steel and Composite Structures, Vol. 8, No. 6, pp. 457–473.
9.
DavalosJ.F.KodkaniS.S.RayI. and BoyajianD.M. (2005). “A fracture mechanics approach for interface durability of bonded FRP to concrete”, Proceedings of the 7th International Symposium on Fiber Reinforced Polymer Reinforcement for Reinforced Concrete Structures, ACI SP-230-86, Kansas, U.S.A., pp. 1465–1480.
GardenH.N.QuantrillR.J.HollawayL.C.ThorneA.M. and ParkeG.A.R. (1998). “An experimental study of the anchorage length of carbon fiber composite plates used to strengthen reinforced concrete beams”, Construction and Building Materials, Vol. 12. No. 4, pp. 203–219.
12.
Japan Society of Civil Engineers (2000). Recommendations for Upgrading of Concrete Structures with use of Continuous Fiber Sheets, Concrete Library, Vol. 7.
13.
KarbhariV.M. and EngineerM. (1996). “Investigation of bond between concrete and composites: Use of a peel test”, Journal of Reinforced Plastics and Composites, Vol. 15, No. 2, pp. 208–227.
14.
LiuI.S.T.OehlersD.J. and SeracinoR. (2007). “Study of intermediate crack debonding in adhesively plated beams”, Journal of Composites for Construction, ASCE, Vol. 11, No. 2, pp. 175–183.
15.
LuX.Z.TengJ.G.YeL.P. and JiangJ.J. (2007). “Intermediate crack debonding in FRP-strengthened beams: FE analysis and strength model”, Journal of Composites for Construction, ASCE, Vol. 11, No. 2, pp. 161–174.
16.
PanJ. and LeungC.K.Y. (2007). “Debonding along the FRP–concrete interface under combined pulling/peeling effects”, Engineering Fracture Mechanics, Vol. 74, No. 1–2, pp. 132–150.
17.
SaadatmaneshH. and EhsaniM.R. (1991). “RC beams strengthened with GFRP plates, Part I: Experimental study and Part II: Analysis and parametric study”, Journal of Structural Engineering, ASCE, Vol. 117, No. 11, pp. 3417–3455.
18.
TengJ.G.ChenJ.F.SmithS.T. and LamL. (2002), FRP-strengthened RC Structures, John Wiley & Sons, NY.
19.
TengJ.G.SmithS.T.YaoJ. and ChenJ.F. (2003). “Intermediate crack-induced debonding in RC beams and slabs”, Construction and Building Materials, Vol. 17, No. 6–7, pp. 447–462.
20.
TengJ.G.YuanH. and ChenJ.F. (2006). “FRP-to-concrete interfaces between two adjacent cracks: Theoretical model for debonding failure”, International Journal of Solids and Structures, Vol. 43, No. 18–19, pp. 5750–5778.
21.
WanB.SuttonM.A.PetrouM.F.HarriesK.A. and LiN. (2004). “Investigation of bond between fiber reinforced polymer and concrete undergoing global mixed mode I/II Loading”, Journal of Engineering Mechanics, ASCE, Vol. 103, No. 12, pp. 1467–1475.
22.
WuZ.S.YuanH.AsakuraT.YoshizawaH.KobayashiA.KojimaY. and AhmedE. (2005). “Peeling behavior and spalling resistance of bonded bidirectional fiber reinforced polymer sheets”, Journal of Composites for Construction, ASCE, Vol. 9, No. 3, pp. 214–226.
