Carbon Fiber Reinforced Ribs In Hygrothermal Environment Creep Performance Study

Corrosion of steel bars is one of the important reasons for the degradation of bridge service performance.Carbon fiber reinforced composite materials(CFRP)have the advantages of light weight,high strength,and corrosion resistance,and are gradually popularized and applied in bridge construction.In this paper,the creep properties of CFRP bars under different working conditions(drying at normal temperature,water immersion at normal temperature,drying at high temperature,and hot and humid environment)and different stress levels are studied.The main research contents and results of this article are as follows:(1)Based on mechanical analysis and experimental methods,the endwedge embedded anchoring system of carbon fiber reinforced(CFRP)tendons was researched.It was found that the anchoring system can not only avoid the occurrence of shear failure,but also effectively solve the problem caused by insufficient bonding force Anchor failure problem;tensile and shear properties of CFRP bars were tested by tensile and short beam shear tests.(2)Based on the principle of leverage,a CFRP tendon creep test device was designed and manufactured;and the creep properties of CFRP tendons under different stress levels were studied under room temperature drying,room temperature water immersion,high temperature drying,and hot and humid environments.The results show that during the test period,the strain of CFRP bars under normal temperature drying and water immersion slowly increases;under high temperature drying and high temperature water immersion environments,the creep deformation of CFRP bars first rises and then decreases;The size has no significant effect on the creep properties of CFRP bars.The creep properties of CFRP tendons in different environments are attributed to the hydrolysis of the resin matrix at high temperatures,debonding at the resin-fiber interface,and post-cure.(3)The residual strength and shear strength of CFRP tendons after creep aging in four environments(drying at normal temperature,immersion at normal temperature,drying at high temperature,and hot and humid environment)were studied.The results show that the creep process of CFRP bars has little effect on the tensile properties of CFRP bars under different environmental and stress conditions;however,the shear strength of CFRP bars under humid and hot environments varies greatly with the environment.Significant effect.After two months of high temperature water immersion,the shear properties of CFRP decreased by 22.6%;its thermal properties(storage modulus,loss factor,and glass transition temperature)were different to one degree after one month and two months.Degradation has occurred.