Study On Tensile Strength Test And Influence Factors Of CFRP

With the development of bridge reinforcement technology,prestressed carbon fiber board reinforcement technology has been increasingly used in bridge reinforcement projects.As a new type of prestressed material,carbon fiber board has very different material characteristics from traditional prestressed steels due to the large differences in the manufacturers’ raw material channels,production processes,especially the carbon fiber board materials used in the current project.The actual condition of carbon fiber boards is uneven.In order to test the actual tensile strength of different carbon fiber board materials,the team developed a special multi-functional test bench and conducted in-depth research on its influencing factors.Through the research of this topic,the following main conclusions are obtained:(1)The stress characteristics of CFRP board of different lengths is basically the same and presents a linear relationship.With the increase of the length,the ultimate load carrying capacity of carbon fiber board is slightly reduced,but the effect is not obvious.This conclusion has great significance for determining the sampling length of the carbon fiber board.(2)After the ultimate rupture of CFRP board,the internal part of the anchorage had no obvious slip,but most of the fracture is near the anchorage,indicating that the anchorage has a certain influence on the tensile strength of the cross section near the end of the carbon fiber board.Theoretical analysis shows that the end of the carbon fiber board is not evenly stressed,which has a certain influence on the ultimate strength of the test.(3)Due to the influence of the manufacturing process,some carbon fiber boards are bent or distorted in the plane when the carbon fiber board is shipped from the factory.To facilitate the description of this production error,this article defines this phenomenon with “flat bending error” and gives this kind of phenomenon and the theoretical formula of the effect of error on the tensile strength of carbon fiber board.(4)With the increase of “flat bending error” or the increase of horizontal curvature radius,the greater the same section strain difference is,the more inhomogeneous stress distribution is.the more obvious the carbon fiber board cross section is.The more unfavorable stress is,the greater influnence on the tensile strength of the carbon fiber board is.Therefore,in the carbon fiber board quality control,“flat bending error” should be strictly limited.The above conclusions have important reference value for the design value of carbon fiber board material strength and the quality control of carbon fiber board.