Study On Chloride Ion Erosion Model And Experiment Of PC Bridge

Prestressed bridges are considered to have good durability due to the fact that they work without cracks.In fact,however,prestressed bridges will also suffer from durability problems.The characteristics of the prestressed bridge determines the sudden failure and the consequences.Therefore,it is of great practical significance to study the durability of prestressed bridges.Chloride ion erosion is one of the most important factors that lead to the durability of concrete structures,and this paper mainly studies the durability of prestressed concrete bridges from chloride ion erosion.The study on the chloride ion erosion model of prestressed concrete bridge often starts from the influence of the load on the permeability of concrete.At present,the majority of scholars obtain the qualitative judgment or empirical formula of load effect on the chloride ion transfer,and few scholars study the tansport of chloride ion in concrete from the influence mechanism of load effect on microstructure of concrete and do theoretical research and then establish the load-chloride ion transport correction coupled model.In this paper,the effects of load on the pore structure of concrete are analyzed,and the influence of the load on the diffusion behavior of concrete is analyzed,and the chloride ion erosion model is established.The reliability of the model was verified by the salt spray corrosion test of the concrete beam.The main contents and conclusions of this paper are as follows:(1)The influence mechanism of carbonation on chloride ion transport was studied,and the correction model of carbonation effect on chloride diffusion coefficient was established.(2)Load effects change the characteristics of pore structure of concrete is the essence of the change of concrete permeability;Pore structure changes include elastic deformation and damage;Based on the consideration of chloride ion in concrete strain,damage and porosity,the correction of chloride diffusion coefficient is proposed.(3)On the basis of the existing research results,combined with the mechanism of the effect of load on chloride ion diffusion,the chloride ion erosion model of prestressed bridge is established.(4)The relationship between the load,carbonation,chloride diffusion coefficient and water diffusion coefficient was established,and the coupling relationship between them was established.(5)Salt spray corrosion test of concrete beams under the loading condition was carried out,and the theoretical model was solved by finite element software,and the results show is a good correlation between the experimental results and the chloride ion erosion model.