Numerical Simulation Of Flexural Performance Of Damaged Prestressed Reinforced Concrete Box Girder

Prestressed reinforced concrete box girder is widely used in bridge engineering owing to its light weight and perfect torsional performance.During the service of bridge,the service life of prestressed reinforced concrete box girder will be shortened by the damage of reinforcement corrosion,concrete carbonization,the section defect of concrete and non-compacted grouting of prestressed reinforcement duct.Due to the limitation of testing conditions,this paper establishes a three-dimensional finite element model of prestressed reinforced concrete box girder by ANSYS software,and aims to simulate and analyze the deterioration of flexural performance of prestressed reinforced concrete box girder.Meanwhile the effects of reinforcement corrosion,concrete carbonization,the section defect of concrete and non-compacted grouting of prestressed reinforcement duct are taken into consideration.Moreover,the relationship between mechanical performance parameters of prestressed reinforced concrete box girder and reinforcement corrosion rate,fatigue loading frequency is established under the action of fatigue load.The main research work is listed as follows:(1)Establish a finite element model of prestressed reinforced concrete box girder and validate its correctness.The prestress application is simulated by temperature cooling method.The spring element is selected to connect concrete element and reinforcement element aims to simulate the bond slip between reinforcement and concrete.The bearing capacity of box girder is calculated by the empirical formula to verify the correctness of the finite element model of prestressed reinforced concrete box girder.(2)Numerical simulation on the flexural performance of prestressed reinforced concrete box girder with the effect of reinforcement corrosion.The numerical calculation of the flexural performance of prestressed reinforced concrete box girder with different degrees of reinforcement corrosion is completed,and the effects of reinforcement corrosion rate on the load displacement curve,concrete load-strain curve,reinforcement load-slip curve and reinforcement strain are analyzed.(3)Numerical simulation on the flexural performance of prestressed reinforced concrete box girder with the effect of concrete carbonization.The temperature field is applied to simulate concrete carbonization,and the variation of load-displacement curve,stress distribution of prestressed reinforcement,the stress of concrete in mid-span and the overall stress distribution of prestressed reinforced concrete box girder under the effect of concrete carbonization depth are analyzed.(4)Numerical simulation on the flexural performance of prestressed reinforced concrete box girder with the effect of concrete section defect.The box girder model of concrete section defect is established by the life and death element technology.The relationships between the defect rate of concrete section and the ultimate bearing capacity of prestressed reinforced concrete box girder,the load displacement curve in the mid-span,the lowest point stress in the mid-pan and the area of compression zone are explored.(5)Numerical simulation on the flexural performance of prestressed reinforced concrete box girder with the effect of grouting defects.Considering the effect of grouting defect location and length,the variation laws of mid-span load displacement curve of box girder,the compressive strain of concrete in box girder section,the height of compression zone and the ultimate strength of box girder are investigated.(6)Numerical simulation of the flexural performance and fatigue life prediction of damaged prestressed concrete box girder with the action of fatigue load.The numerical calculation of flexural performance of prestressed reinforced concrete box girder with different corrosion degree under fatigue load is completed.The variation of concrete strain,steel strand strain,mid-span deflection,yield load and cracking load with reinforcement corrosion rate and fatigue load frequency are analyzed.Based on Miner cumulative damage theory and Elastic-Plastic hypothesis,the fatigue life of box girder is predicted.