Study On Variable Stiffness Anchorage System For Carbon Fiber Ribs And Cables

Corrosion fatigue exists in steel cable of bridge structure,which seriously affects the safety and service life of bridge.Carbon fiber reinforced composite(CFRP)has the advantages of light weight,high strength,corrosion resistance and fatigue resistance,and can be used in bridge structures instead of steel cables.However,as a typical anisotropic material,the shear and compressive properties of CFRP are far less than the tensile properties,which makes the anchorage of CFRP extremely difficult.The difficulty in anchoring CFRP bars or cables has become one of the main problems restricting its wide application in civil engineering.The anchoring problems of CFRP bars and cables have been studied extensively at home and abroad,and the anchors of friction type,bond type and combined type have been developed.However,the anchoring technology is not mature as a whole,especially for the CFRP cable with multiple bars and large tonnage,it is urgent to develop an anchoring system with high anchoring efficiency,so that CFRP cable can be used in bridge structure instead of steel cable.Aiming at the above problems,the anchoring system of CFRP bars and cables is studied in this paper.By optimizing the existing CFRP bars and cables anchoring system,a new type of high anchoring efficiency anchoring system is obtained.Specific research contents include:Experimental study on material of CFRP bar and cable anchor.The constitutive tests of anchorage materials of CFRP bar and cable anchorage system are carried out to obtain their constitutive parameters.The production scheme of the variable stiffness binder is put forward,and the static load test of the variable stiffness binder is carried out,and the variation rule of the stiffness of the binder and the proportion of the component of the binder is obtained.The bending Angle range of CFRP bar bending anchorage system was obtained by the bending test of CFRP bar.For the design of the new anchor to pave the way.Theoretical and simulation analysis of existing CFRP bar and cable anchor system.The mechanical analysis of wedge-type clamp-type anchorage and bond-type anchorage is carried out by means of theory and finite element simulation.The stress distribution of the anchoring system and the variation law of stress with anchoring parameters are obtained.Based on the maximum bearing capacity of CFRP bars,the size design formula of the new anchor is obtained,and the internal forces of the common anchor and the optimized anchor are compared and analyzed.Design,manufacture and static load test of new anchoring system of CFRP bars and cables.The design,manufacture and static load test of variable-stiffness clamp-type anchorage and variable-stiffness bond-type anchorage are carried out,and the complete manufacturing process of anchorage is obtained.On this basis,a new type of CFRP cable anchor system is designed by using variable stiffness binder and bending bar bundle.Furthermore,the production and static load tests of the new CFRP cable anchor system are carried out,and the anchoring efficiency of the new CFRP cable anchor system is evaluated by the failure mode and cable anchor slip curve obtained from the tests.The main innovation of this paper is to optimize the anchoring system of the existing CFRP bars and cables.Based on CFRP bars and multi-bar CFRP parallel bars and cables,a new type of high anchoring efficiency CFRP bars and cables anchoring system was designed.In this paper,a new design scheme of variable stiffness bonding material is proposed,which provides a new design idea for the research of CFRP bars and cable body anchoring system.In this paper,through rigorous theoretical and simulation analysis of CFRP bars and cables anchoring system,a new type of anchoring system is designed,which is helpful to solve the problem that CFRP bars and cables are difficult to anchor.The new type of cable anchoring system with high anchoring efficiency proposed in this paper is conducive to the extensive application of CFRP materials in civil engineering,especially in long-span bridge structures.