Study On Coupling Analysis Method Of Chloride Erosion And Steel Corrosion Expansion In Reinforced Concrete

Chloride ions erosion is a prominent problem on the durability of marine reinforced concrete structures.Chloride penetrating to the inner of concrete lead to the steel corrosion and the volume expanding of steel corrosion product causes concrete protective layer cracking,which significantly affects the transfer path of chloride ions in concrete,thus further aggravate the steel corrosion.Therefore the penetration of chloride ions as well as the erosion of rebar in concrete are two nonlinear mutually strengthening and coupling processes.It is of great theoretical significance and a promising prospect in engineering practice to research on numerical method and simulation technology for the coupling problem.This paper thoroughly studies on the process coupling analysis method for chloride ions erosion and concrete damage caused by steel corrosion,the realization of automatic analysis process and the damaging process of reinforced concrete structure.The main innovative work and results are as follows:(1)The process coupling analysis method is proposed.The chloride ions erosion and the evolution of concrete damage are the different physical and mechanical processes.In this paper,the coupled solution is realized by exchanging and controlling the dynamic data between the different process,as well as fully automated generation and updating models.With ABAQUS software platform,the proposed method is realized by programming user subroutine and interface program.Using the experimental data,the correctness and efficiency of the proposed method are verified.(2)For the steel corrosion expansion,the mechanics equivalent method is established.three loading methods are used to simulate the volume expanding of non-uniform steel corrosion,including the equivalent displacement loading,the equivalent node temperature loading and the dynamic temperature linear expansion coefficient loading.The advantages and disadvantages of the three mechanics equivalent methods and their applicable analysis process are discussed.(3)In the meso-concrete,the coupling method between the heterogeneous time-varying diffusion and the damage evolution process is developed.Based on the proposed method,the secondary development of ABAQUS software in Python and Fortran language is carried out to update the heterogeneous time-varying diffusion coefficient in real time.And this program solve the fully automated modeling of meso-concrete with interface transition zone(ITZ).For the chloride ions erosion into the meso-concrete,the established method realizes the complete analysis from the different materials damage in the meso-scale to the concrete members failure.(4)A new idea for design of marine reinforced concrete structures is presented.According to the characteristics of marine reinforced concrete exposed to high chloride ions environment,the sensitivity analysis of the key parameters in structural design was made by the developed process coupling analysis method,such as reinforcement spacing,reinforcement diameter,reinforcement ratio and so on.The analysis results theoretically explain the premature failure of marine reinforced concrete structures.It is suggested that the reinforcement should be combined with structural bearing capacity and durability in the design of marine reinforced concrete structures.This paper enriches and develops the basic methods in the durability of reinforced concrete structures.and it provides a new analytical method for the design of marine reinforced concrete structures.