Test Method Of GFRP Reinforced Concrete Bonding Performance

Fiber Reinforced composites has many advantages,such as light weight,high strength?corrosion resistance?heat-shielding performance?insulating property and so on.The bond property between FRP bars and concrete is the important guarantee of work together.so the theoretical research to the bonding performance between the fiber reinforced plastic reinforcement and concrete is important.At present,there are some methods for the research on the bond slip behavior of FRP reinforced concrete.The test method of the single ended drawing test and beam test.We design a new kind of method for pull-out test;double reinforcement on tensile test.This new method not only is easy to operate but also can make the strained condition close to practical,data is more reliable.In this paper,we carried on the double reinforcement on tensile test for 36 specimens of GFRP tendons concrete.By contrast the bonding strength?Slip value under the condition of different parameters,Analysis of the main factors affecting the GFRP reinforced concrete bond behaviors:diameter of GFRP bar?concrete strength?thickness of concrete protective cover?anchorage length of GFRP bar.With the level of increase as the concrete strength,bond strength specimens have a slight increase;Ribbed bonding properties between GFRP rebar and concrete than light round of GFRP bars superior and more;Bond strength decreases with increasing diameter;Bond strength decreases with increasing length of anchor,Similar effects of different diameters FRP bars for specimens;The thickness of the protective layer of concrete GFRP reinforced concrete bond behavior has little effect.Through the test for double reinforcement to pull,we found that The failure mode of specimen have 2 types:pull-out failure of GFRP bar?splitting failure of concrete.Tests showed that most of the damage in the form of specimens of FRP tendons pulled destroyed,such destruction in the form of typical damage.Though the double reinforcement on tensile test for 36 specimens of GFRP tendons concrete,we got the load-displacement curve.By the research for the load-displacement curve of bond-slip between GFRP bar and concrete and theoretical analysis for mechanism of bond-slip,this text established a new sectional type constitutive models for bond slip relation of GFRP tendons concrete.Curve can be divided into the following four stages:ascent stage?slip stage?softening stage?remnant stage.By the research for the curve of test and the model curve,we know that the model can reflect the whole process of interaction of GFRP bars and concrete accurately,the model curve and the curve of test close resemblance.