Durability Study Of Concrete Structures Based On Chloride Ingress

Concrete structures often causes the corrosion of steel bar due to erosion of chloride ion, thus the structural behavior is degenerated and the carrying capacity is reduced and even the structure is destroyed. In this connection, it is a must to spend a lot of money and natural resources on maintenance and reconstruction. Thus huge economic loss and sever social influence are caused to the state. This paper performs the following research work with focus on the problem of durability of the concrete structures if eroded by chloride ion by taking the initial corrosion durability life of steel bars in concrete as the mainline from three perspectives of numerical simulation method for predicting chloride ion concentration distribution in concrete, numerical model of predicting chloride ion concentration in concrete as well as probabilistic method for predicting durability life of the concrete structure:By utilizing the similarity of differential equation for unsteady state heat conduction & energy conservation in concrete with differential equation for unsteady state diffusion & mass conservation of chloride ions in concrete based on Fick's law and having rational equivalence of each parameter of the equations, propose a finite element numerical simulation method for predicting two-dimensional distribution of chloride ion in concrete based on the thermal analysis module in ANSYS and verify the effectiveness of this method through comparison to the analytic solutions. Study the influence law of diffusion coefficient, diffusion time, chloride ion concentration on the surface, sectional dimension of the constructional element, existence, diameter and space of steel bars on the two-dimensional diffusion of chloride ion in concrete.Revise diffusion coefficients of chloride ion by introducing various parameters based on the foregoing finite element numerical simulation method, establish the numerical module of chloride ion diffusion in concrete under the influence of many factors, discuss the parameters of the module in great detail and give law of taking value for each parameters. Simulate an engineering case by application of the numerical model and verify the practicability of the model through comparison of the simulation value to the experimental value.Based on the foregoing numerical model with the critical concentration that the chloride ion concentration on the surface of the steel bar as the symbol of the termination of durability life and in view the randomness of standard diffusion coefficient of chloride ion, thickness of the protective layer chloride ion concentration on the surface and the critical concentration of chloride ion, based on the PDS in ANSYS establish reliability-based numerical method for calculating the expected value of durability life of the concrete structure and failure probability of durability, then analyze the influence law of the statistical characteristic of each parameter on durability life by application of this method.