Bond Behavior Of Fiber Anchor In Uncracked Concrete

Fiber reinforced polymer has been widely used to strengthen existing reinforced concrete structures due to its advantages such as high strength,low weight and high corrosion resistance.However,debonding of FRP is a typical failure mode when externally bonded FRP is used to strengthen concrete structures.As a result,the effectiveness of the material is limited by debonding of FRP.In order to delay or even prevent premature debonding of externally bonded FRP,most current design codes suggest to use fiber anchor to increase the bonding strength of FRP.The pullout load-displacement model of fiber anchor is fundamental for the research of concrete structure strengthened with externally boned FRP with fiber anchor,however,few models exist to date.This paper proposed the pullout load-displacement curve of fiber anchors in different parameters,using pullout test and finite element method.The research included two parts:(1)A test program on twenty-one specially designed concrete cylinder specimens inserted with fiber anchors was carried out to investigate the pullout load-displacement model.The pullout test of fiber anchor is used to investigate the influence of key factors,such as embedment length,anchor diameter and concrete strength on pullout load-displacement curve and failure mode.The test results showed that the embedment length has the greatest influence on load-displacement curve.(2)Based on the pullout tests,meso-scale finite element method is used in this paper.Very small elements are used to simulate the specimens in different parameters.The size of element is 0.5mm,so that there are enough elements to simulate the crack propagation in concrete layer adjacent to fiber anchor.Through the comparison of pullout test result and finite element modelling result,the accuracy of pullout load-displacement curve and failure mode have been verified.