Study On Bonding Performance Between FRP And Concrete At Low Temperature

Fiber reinforced polymer(FRP)has a high tensile strength,good corrosion resistance and thermal expansion coefficient is close to the concrete,it can be in the complex environment instead of steel bar used in reinforced concrete structure,and in the field of civil engineering has been widely research and application.But in low temperature environment,good bonding between FRP rebar and concrete is to ensure that the load transfer between them and the combination of the premise,so low temperature bonding FRP rebar and concrete performance is an important research subject.In this paper,GFRP bar is used as the research material.The bond performance between GFRP bars and concrete was explored by beam drawing test in low temperature environment.The main contents are as follows:(1)This paper analyzes the bonding mechanism of FRP bars and concrete and summarizes the basic factors that affect the bond performance of FRP bars and concrete.For example,the types of FRP bars,the compressive strength of concrete,the surface structure of FRP bars,the diameter of FRP bars,the thickness of the protective layer,the radial binding force,the bond length and the external environment.we expatiate the bond slip constitutive model of several FRP reinforced concrete,analyze their application scope and condition,and provide help for test data analysis.(2)In order to satisfy the loading at the same time of changing the temperature,Our research group independently developed the mechanical loading test case at low temperature.The performance advantage of this device is:At the same time that the specimen of the test chamber is cooled and kept warm,The target of load and test strain is realized synchronously outside the box by using the reloading device and test system of the external loading device.(3)The bond properties of GFRP bars and concrete in low temperature environment were studied.The results show that,With the decrease of temperature,under the same load,the slip between GFRP bar and concretem decreased by 17%~50%,The effect of the change of bond length and GFRP bar diameter on the bond performance of GFRP bars and concrete was also studied.The results show that the slip between the two is increased by 26%~40% due to the increase of the bond length between GFRP bars and concrete.The bond performance of GFRP bars and concrete decreases with the increase of bond length.Due to the reduction of GFRP bar diameter,GFRP bars and concrete slip decreased by 11%,The bond performance of GFRP bars and concrete increases with the decrease of GFRP bar diameter.