Numerical Simulation Analysis Of Chloride Corrosion Of Concrete Under Bending Load And Freeze Thaw Damage

At present,due to the influence of experimental methods,time,funds,manpower and other factors,it is difficult to study the durability of concrete under the action of multiple factors through experimental methods.The numerical simulation by finite element software can better couple the load,freeze-thaw and other environmental factors,make up for the shortcomings of experimental research to a certain extent,and reduce the test error.In this paper,the experimental data of chloride diffusion in concrete under loading and freeze-thaw cycles are re fitted to obtain all the parameter formulas used in the numerical simulation.In the numerical simulation,assuming that the chloride ion concentration on the concrete surface and inside the concrete at the initial time is 0,the diffusion process of chloride ion in concrete under 0～0.6 times bending load and 0～300 freeze-thaw cycle is simulated by using the solid mechanics module,truss module and dilute substance concentration transfer module of COMSOL software,On the basis of Fick’s second law,a prediction model of chloride ion in concrete considering the effects of load damage and freeze-thaw damage is established.Then,based on the above models,the macro numerical simulation and meso numerical simulation of chloride ion diffusion in concrete under load freeze-thaw cycle are carried out respectively,and the advantages and disadvantages of macro simulation and meso simulation are compared.Based on Fick’s second law,the chloride ion prediction models in concrete under load freeze-thaw damage are established.The results show that:(1)load can accelerate chloride diffusion in concrete.0.5～0.6 times of ultimate bending load has the greatest influence on chloride diffusion.(2)After more than 50 freeze-thaw cycles,the growth rate of chloride concentration in concrete decreases greatly。(3)On the whole,the flexural load freeze-thaw increases the diffusion rate of chloride ion in concrete,but when the diffusion time is short,0.2 times of flexural load can inhibit the diffusion of chloride ion.(4)The simulation results under the meso model are closer to the experimental results,and the longer the diffusion time is,the closer the simulation results are to the actual results.