Anchorage Design Of CFRP-steel Wire Composite Reinforcement And Proportional Equal Stiffness Design Method Of Prestressed Concrete Beam

In the process of long-term service of concrete structures,steel corrosion has become one of the main problems affecting durability,especially in coastal,coastal and saline alkali geological areas.In order to solve the problem of steel corrosion,it is a better way to use fiber reinforced polymer(FRP)instead of steel bar.In order to use CFRP reinforcement instead of prestressed steel strand in prestressed structure and reduce cost,this paper uses high strength steel wire and carbon fiber to make CFRP-steel wire composite reinforcement,and then tests the mechanical properties of CFRP-steel wire composite reinforcement products,and studies and designs the anchorage suitable for the products,which provides the basis for the further design of prestressed concrete structure with FRP steel composite reinforcement 。 The main contents of this paper are as follows:Firstly,five kinds of CFRP-steel wire composite bars with different steel wire volume content and diameter of 5.2mm were manufactured by pultrusion process,and static tensile test and shear test were carried out on the products.The test results show that the stress-strain curve of CFRP-steel wire composite reinforcement is linear elastic.Compared with CFRP bars with the same diameter,the elastic modulus and shear strength of CFRP-steel wire composite reinforcement are improved,and the ultimate strength can still be maintained above 2100 MPa.It is feasible to use high strength steel wire and carbon fiber to make CFRP-steel wire composite reinforcement to reduce the cost.Then,the strength check method and preliminary size determination method of the wedge anchor ring are deduced by using the calculation method of elastic mechanics,and the finite element parameter analysis is carried out using ABAQUS.The influence of wedge length,pretightening force,angle of anchor ring,friction coefficient,wedge type and angle difference on anchorage performance is analyzed.Furthermore,based on the simulation results,four types of wedge anchorage were designed and the anchoring efficiency test was carried out.Combined with the finite element simulation results and test results,it is suggested that when the outer diameter of the anchor ring is 32 mm,the length of the anchor ring is 90 mm,and the angle difference is 0.1 ° to 0.15 ° and the wedge type is two pieces of four open wedge.Finally,by comparing the load-deflection curves of FRP steel composite reinforcement beam and reinforced concrete beam under the condition of equal stiffness design and equal reinforcement ratio design,the design method of proportional equal stiffness is proposed.Taking the Railway Prestressed simply supported beam bridge as the object and combining with the current railway bridge design codes,some calculation formulas are modified theoretically.