The Experimental Research On Bond Bahavior Between BFRP Rebars And The Concrete

One of the effective ways to avoid the problem of corrosion of steel reinforcement in concrete is to use fiber reinforced polymer(FRP) reinforcing bars as alternative.However,the existing FRP rebars have deficiencies,which restrict the application of this approach,.the emergence of BFRP rebars provide new space for development.Because of the differences between FRP bar and steel bar in the production technique and mechanical properties,and Different FRP reinforcement have the different bonding properties,so it is necessary to study the bonding properties between BFRP rebar and concrete.the bond stress of FRP bar embedded in concrete is not as good as steel bar embedded.Good bond behavior between FRP bars and concrete is a fundamental issue for reinforced concrete,and it is meaningful for the application of FRP bar in the civil engineering to improve the bond performance of BFRP bar and concrete.Therefore,pull-out tests,beam tests are performed in this paper,with emphasis on the bond behavior and bond-slip relationship between BFRP rebars and concrete. Meanwhile,analysis of the bond anchorage performance is also carried out.The major contributions are summarized as follows:1.Through the analysis of the typical bond-slip curve obtained by the pull-out tests,The characteristic of each stage,the process of bond failure and failure mode are studied. Moreover,a comparison between the bond behavior of GFRP rebars and steel bars embedded in ordinary concrete is drawn.2.Based on the results of the pullout tests,the influences of the thickness of concrete cover,anchorage length,bar diameter on anchorage behavior is studied.The results of experiment show that the ultimate bond strength enhances with the increase of cover thickness,but the increase is not unlimited.3.Through the beam tests,the anchorage behavior under moment and shear is studied. Compare with the pull-out test,the ultimate bond strength of beam test is smaller than that of pull-out test.4.based on the test results and former works,the ascending branch of the bond-slip curve is modeled,and the modeled curve corresponds with the test curve greatly;In addition, a new equation for bond strength and embedment length of BFRP rebar is proposed and provide principles for design code,which takes types of BFRP bars,position in the cast into consideration.