Optimal Design And Performance Evaluation Of Integral Anchoring System With Large Tonnage FRP Cable

Fiber Reinforced Polymer(FRP)has been widely used in the field of civil engineering and has broad prospects because of its advantages such as high strength,fatigue-resistance and corrosion-resistance.As a novel type of FRP,basalt fiber reinforced polymer(BFRP)has many characteristic advantageous such as good stability,excellent mechanical properties,low cost,environmental protection,electrical insulation,and thermostability.The adoption of FRP cable as a tensile component is considered to be the most efficient form to take full advantage of the high tensile strength of FRP material.Since BFRP cable has an advantageous cost performance,it has a significant competitiveness in the long-span bridge in the future.However,the immature large-tonnage FRP cable anchorage system has been restricting the application of FRP cable in major engineering.The existing FRP cable anchoring method is suitable for single tendon or small-tonnage FRP cable group anchors,without a safe,reliable and efficient application for large-tonnage FRP cable group anchor system.Therefore,based on BFRP cable,the following three parts of the study were carried out in this paper:(1)The critical relationship between the friction coefficient of FRP cable at anchorage zone-load transfer medium and that at medium-steel sleeve is discussed respectively.The theoretical bearing capacity of cable anchorsystem is derived.The finite element analysis based on ANSYS was used to analyze and optimize the 500-ton FRP cable anchorage.After the optimization,the stiffness of the anchorage zone medium was divided into 4 section and the anchorage length was optimized to be 1000mm.The cable-medium interface was strengthened to enhance the anchoring force.Suggestions and approaches are proposed for the optimization design of FRP cable anchor system.The load transfer medium of the novel large-tonnage FRP cable anchors with different types of fiber rovingis developed,and the method of grooving on the anchorage is proposed to release the circumferential deformation of anchorage.(2)BFRP cable integral anchoring systems consists of 37 ? 4mm tendon are manufactured based on the optimized design and technology.The static tensile test is conducted on the BFRP cables.The integral stiffness of the cable is measured to be 63.9GPa,and the relative slippage of the FRP cable anchorage zone is consistent with the results of finite element analysis.The shear stress distribution mode and the gradual stiffness of the anchorage zone are close to the results of finite element analysis.The mean value of the efficiency coefficient of FRP cable anchorage is calculated to be 0.98.(3)The fatigue test set-up of FRP cable was designed.The fatigue performance of 37 ?4mmBFRP cable integral anchors is studied.It is mainly concluded that the cyclic load has little effect on the FRP cable combination effect.The relative stiffness of the FRP cable is increased slightly by cyclic load.The relative slippage of the anchorage zone increases with the increase of cycles and tends to be stable after a certain cycles.The main reasons for the insufficient fatigue strength include the poor consistence of the tendons at free end,the initial damage in the tendons,the excessive large stiffness at the loading end of the load transfer medium and the insufficient thickness.