Corrosion Fatigue Analysis And Reinforcemen Method Of Reinforced Concrete Bontinuous Beam Bridge

Reinforced concrete continuous beam bridges are widely used,but many of the existing reinforced concrete bridges have to be strengthened or rebuilt because of the corrosion and fatigue of the reinforcement caused by cracking.It is the first difficulty to judge whether the reinforced concrete bridge needs reinforcement and reconstruction,so it is of great significance to evaluate the reinforced concrete structure after corrosion and fatigue.In this paper,the structural rigidity after cracking,the change of bond stress of reinforced concrete after corrosion fatigue and the selection of reinforcement scheme for Mulan bridge,which has been built,are studied.The main work is as follows:(1)This paper reviews the fatigue properties of steel and concrete and the research history of bond slip between steel and concrete.(2)Based on the bond slip constitutive relation given by the code and the test results of others,the influence of corrosion and fatigue on bond slip is analyzed,and the bond slip constitutive relation of reinforced concrete under arbitrary fatigue and corrosion is given.(3)This paper expounds the formation process of cracks in reinforced concrete structures,and deduces the crack spacing,crack width and structural rigidity of reinforced concrete flexural members after cracking.Combined with the paper,the paper presents the recommended formula of bond stress distribution between cracks and the nonuniformity coefficient of reinforcement between cracks.The method of reducing the crack width by reducing the diameter of reinforcement or increasing the reinforcement ratio is put forward.(4)To verify the correctness of the bond slip formula of reinforced concrete after corrosion fatigue,and to compare the influence of corrosion and fatigue on bond slip,it is concluded that the bond stress between reinforced concrete decreases with the increase of corrosion rate under the same corrosion rate.When the corrosion rate is 8%,the bond stress has a sudden drop,which is easy to cause the sudden increase of bridge deflection and brittle failure in the actual project.In addition,corrosion has no effect on residual strength and residual slip.Fatigue does not change the splitting strength,ultimate strength and residual strength,but it has an effect on each slip,and the residual slip has the greatest effect.(5)Using ABAQUS to establish the whole bridge model,the stress amplitude of the reinforcement under the vehicle load is 33.7MPa,and the corresponding fatigue life is 16.63 years,so the reinforcement measures should be taken.In the ultimate state of bearing capacity,the stress of reinforcement is 210MPa,which does not reach its tensile strength of 284MPa.(6)According to the actual situation of Mulan bridge,it is recommended to adopt the method of sticking steel plate for reinforcement.After the finite element modeling,the stress of the reinforcement under the vehicle is 5.9MPa,and then the fatigue life is 1.27×106 years,far beyond the design life,which meets the design requirements.