Research On The Ductility And The Calculaing Methed Of A CFRP Prestressed Concrete Continuous Beam

CFRP tendons are suitable for reinforced concrete structure due to its corrosionresistance, thus corrosion of the tendons is effectively solved and durability of the structure isimproved. CFRP tendons are linear elastic materials and have no yield point. So the existingreinforced concrete ductility theory is no longer suitable for concrete structure with CFRPtendons. Now the study on ductility and calculation methed of a CFRP prestressed concretecontinuous beam is limited and has not yet form a unified theory. This paper adopts thecombined method including numerical simulation and theoretical analysis to study theductility and calculation methed of the beam.Firstly,we did a nonlinear finite element analysis of CFRP prestressed concretecontinuous beam by ANSYS software.The reliability of finite element model was proved bythe experiment.Parameter analysis of a CFRP prestressed concrete continuous beam is carried out,thenanalysis the cracking load, ultimate load, ultimate stress of CFRP tendons moment-curvaturecurve. Study show that: both of the CFRP reinforcement ratio and controlled tensioned stresshave great influence on the characteristic values, other factors such as concrete strength,reinforcement ratio of tensioned steel, have an impact on ultimate load only, and for the restof the characteristic values have no obvious effect. The moment-curvature curve changes overthe CFRP reinforcement ratio and reinforcement ratio of tensioned steel, other factors have nosignificant effect on the moment-curvature curve.According to the results of the finite element analysis, a formula for calculatingcurvature ductility of the CFRP prestressed concrete continuous beam is proposed and thedesign target state in the formula is also given. The values of the curvature ductility index is1.18~4.18. The influence factors of the ductility are studied. The result show that: thecurvature ductility increases with the increase of CFRP reinforcement ratio; concrete strengthhave no obvious effect on the curvature ductility; the curvature ductility increases with theincrease of level of prestressing when the steel reinforcement ratio is low; the curvatureductility increases with the increase of reinforcement ratio of compressed steel, the moreobvious the increase. Last, a simplified formula for calculating curvature ductility of the CFRP prestressedconcrete continuous beam is established on parameter of integrated reinforcement index andthe limit design value is also proposed as2. In addition,0.16~0.308and0.288~0.492aresuggested for integrated reinforcement index and level of prestressing.