Study On The Bond Behavior And The Distinction Of Bond Mechanism Between Deformed GFRP Bars And Deformed Steel Bars

The performance reduction of reinforced concrete’s safety and applicability structure caused by corrosion problem of steel bars results in concrete structure’s durability failure finally. Using fiber reinforced polymers bars as reinforcement in concrete structures is considered to be a possible alternative to part of reinforcing steel bars, which has been applied to more and more engineering construction fields.However, in contract to reinforcing steel bar, there is still no standard deformation for the surface characteristics of FRP bars yet, Therefore, for a broader range of application of FRP bars in engineering construction field, It’s a fundamental requirement to determine the bond behavior of commercial FRP bars with various types. The behavior of FRP bars is determined by the mechanics of bond stress transfer between FRP reinforcement and concrete, and also by the surface stress behavior of both.In order to study the bond mechanics and bond behavior between FRP reinforcement and concrete during the pull-out test, for a supplement to experimental study as well, this paper builds three finite element models with different deformation, helical wrapping, grooved and helical ribbed respectively. The finite element model of steel bar has the same deformation with helical ribbed one, for the analysis of stress nephogram and bonding strength during the different load step. The main research content are as follow:(1) On the basis of the existing researches, bond-slip theory of FRP bars in concrete is summarized in this paper, include constitutive relation of bond-slip relationship and several influential factor affect bond behavior.(2) In contrast to the experimental result, finite element models are set up to verify the suitability of selection of element type and numerical solution method.(3) This paper collected mechanical property and the deformation’s geometry parameter of several FRP bars with different deformation and selected three widely used types of FRP bars and one rolling thread steel bars. According to those types, the mechanics of bond and the difference of bond behavior are obtained by simplifying the geometrical model and analyzing the stress response.(4) A new equation for bond strength and development length of GFRP bars and embedment length is proposed based on the finite element numerical analysis results.