Two-Dimensional Numerical Simulation Approach For Reinforced Concrete Considering Diffusion Of Chloride

In recent years,the problem of rebar corrosion in reinforced concrete structures has become more obvious.The result that spalling of concrete cover and reducing of the structure bearing capacity has caught industry participant's attention.The corrosion by chloride ion is the primary cause of steel corrosion.With the increasing of rebar corrosion degree,the increasing press by the expanding will lead the cracking of the surrounding confined concrete,at the same time,structural longer service life has been influenced.Therefore,the durability of reinforced concrete structure with the rebar corrosion and cracking by expanding oxidative products has the extremely vital significance.This paper chiefly research the cracking due to corrosion expansion with the chloride ion erosion in reinforced concrete structure.Through numerical simulation of chloride ion diffusion in concrete and concrete cracking due to rebar corrosion has been programmed,the influence factor of chloride ion diffusion speed just like aggregate,bar diameter,temperature,humidity has been studied,the influence factor of concrete cracking like bar diameter,thickness of concrete cover has been researched.The expanding press of rebar uniform corrosion and rebar non-uniform corrosion has been calculate.This paper introduces the basic theory of diffusion and prediction model,analysis the influence factors of the chloride ion diffusion,established chloride ion diffusion model under the various factors.To study the influence of diffusion coefficient and analysis the influence of aggregate boundary layer,model takes temperature,humidity,water cement ratio,chloride ion concentration into account.In this paper,corrosion morphology of chloride ion diffusion model was established.According to the reinforced concrete chloride ion diffusion model,calculate the steel surface chloride ion density,rebar corrosion quantity calculation model was put forward.On the basis of rebar corrosion quantity calculation model,the influence of rebar corrosion like reinforced protective layer thickness,reinforcement diameter,reinforcement location has been studied.Through the rebar corrosion quantity calculation model,the corroded expansion pressure calculation method was put forward.In the process of reinforcement corrosion expansion,the blend system composed by corrosion product and rebar was pressed due to the restraint of surrounding concrete.The pressure value was calculate by the elasticity modulus of blend system and its strain.Lattice cracking model is established in this paper,it can calculate the expansion pressure at rebar node.For the rebar non-uniform corrosion,Corrosion expansion pressure value changes with quantity of reinforcement.The rebar corrosion expansion pressure calculate by chloride ion diffusion model was transformed to the equivalent stress at the node in the lattice model.According to the basic principle of lattice model,two-dimensional concrete lattice model based on the model of random aggregate of concrete was established.The corrosive cracking of concrete can be simulated by adding rebar expansion pressure form rebar's corrosive forms.By simulating the corrosive cracking of reinforced concrete,the influence of concrete cover cracking like rebar diameter,layer thickness,rebar position was researched.Meanwhile,the natural corrosion experiment can be simulated in the same way.By comparing simulation results with the test result,the feasibility and defects of this method can be demonstrated.