CN112307662B - Numerical method for bolt corrosion simulation - Google Patents
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Abstract
The invention provides a numerical method for simulating bolt corrosion. The method is based on a numerical simulation mode of an electrochemical reaction principle, and the corrosion form of the stud in the steel-concrete combined structure is intuitively analyzed, so that the time-varying bearing capacity degradation analysis of the stud under the corrosion condition can be carried out. The method solves the problem that the bolt corrosion detection and monitoring in the concrete are difficult. The method has the advantages that chloride ion diffusion and stud corrosion coupling analysis in the concrete are carried out, numerical simulation of the stud corrosion process in the service period of the combined structure is realized, the corrosion process is given, and the method can be used for analysis and evaluation of the steel-concrete combined structure.
Description
Technical Field
The invention relates to the technical field of corrosion numerical simulation, in particular to a numerical method for bolt corrosion simulation.
Background
The existing detection method for steel corrosion in concrete comprises damage detection and nondestructive detection. The damage detection is only used when the steel material in the concrete structure is seriously rusted. The damage detection method is to chisel the damaged concrete until the bolt in the concrete is exposed, and then observe the corrosion of the bolt by naked eyes. Non-destructive testing includes physical testing and electrochemical testing. The physical detection mainly comprises a resistance rod method, a vortex detection method, an acoustic emission detection method, a ray method, an infrared thermography method and the like; the electrochemical detection method mainly comprises a natural potential method, an alternating-current impedance spectroscopy method, a polarization resistance method, a constant-current method, a concrete resistance method, a current step method and the like.
Although the above detection technology is widely applied to engineering practice, the following problems still exist:
1) the damage detection can damage the whole structure and is only suitable for the corrosion detection of the steel with serious corrosion;
2) the nondestructive testing is to collect signals generated by the corrosion of the steel by a testing instrument or equipment so as to evaluate the corrosion condition of the steel, and the method can only test the local corrosion condition of the steel and can not determine the overall condition and degree of the corrosion of the steel;
3) the detection instrument or equipment of the nondestructive detection can be interfered by signals of different degrees, and the precision of the detection instrument or equipment can not be effectively ensured sometimes;
4) the nondestructive testing is an indirect testing method, and the corrosion condition of steel cannot be intuitively obtained.
Therefore, there is a need to develop a numerical method that can intuitively analyze the corrosion morphology of studs in steel-concrete composite structures.
Disclosure of Invention
The invention aims to provide a numerical method for simulating bolt corrosion, which aims to solve the problems in the prior art.
The technical scheme adopted for achieving the aim of the invention is that the numerical method for simulating the corrosion of the bolt comprises the following steps:
1) intercepting a modeling area of any single stud in the steel-concrete composite beam bridge to be analyzed, and specifying geometric parameters of the modeling area. In the modeling area, concrete is represented by a cuboid area, and the studs are represented by a stepped rotary body area. The step-shaped revolving body comprises two cylinders which are overlapped up and down. Six faces of the cuboid are concrete boundaries, and five faces of the stepped rotary body are stud boundaries. The studs are arranged in the concrete, the area between the concrete boundary and the stud boundary being the concrete filling area.
2) And constructing a concrete and stud finite element model and carrying out grid division.
4) A pin corrosion numerical simulation finite element program is compiled based on an electrochemical principle.
5) The evaluation period T is divided into a plurality of calculation steps in time steps Δ T. And (4) running a bolt corrosion numerical simulation finite element program, and calculating to obtain the bolt corrosion condition in the evaluation period T.
And 5.1) carrying out stud blunting judgment until anode nodes appear on the surface of the studs.
5.2) simulating the development of the stud corrosion.
6) And (5) carrying out visualization processing on the corrosion condition obtained in the step 5) to obtain the corrosion form and corrosion amount cloud chart of the stud.
Further, in the step 2), meshing is carried out on the finite element model by adopting tetrahedral or hexahedral mesh units.
Further, before the step 5), a relevant step of determining a chloride ion invasion path is provided.
Further, the step 5.1) specifically comprises the following steps:
5.11) obtaining t from the numerical simulation of chloride ion diffusion i The time of peg surface chloride ion concentration.
5.12) performing blunt judgment on all nodes on the surface of the stud. And when the chloride ion concentration at the node is less than the chloride ion inactivation threshold, the node is judged to be a cathode node. And when the chloride ion concentration at the node is greater than or equal to the blunt threshold, determining that the node is an anode node. When the anode node appears on the surface of the pin, the surface of the pin is blunt.
5.13) repeating the steps 5.11) and 5.12) to calculate the next time step until the surface of the pin has anode nodes.
Further, the step 5.2) specifically comprises the following steps:
5.21) obtaining the surface chloride ion concentration of the stud at the t moment by numerical simulation of chloride ion diffusion.
5.22) obtaining the cathode and anode point distribution of the surface of the stud. And when the chloride ion concentration at the node is less than the chloride ion inactivation threshold, the node is judged as a cathode node. And when the chloride ion concentration at the node is greater than or equal to the blunt threshold, determining that the node is an anode node.
5.23) iteratively calculating the corrosion rate and the corrosion amount in the time step of delta t. After iterative convergence, rust in the next Δ t time step is calculated. And (4) superposing the corrosion amount of each delta t time step to obtain the overall corrosion state.
5.24) cumulative calculations are performed for each time step until the final time T is calculated.
Further, in step 5.23), the corrosion calculation flow of a single time step comprises the following steps:
a) and calculating the electric field, and calculating the actual current density of the node.
b) And (4) carrying out oxygen transmission calculation to obtain the actual oxygen concentration of the cathode and anode nodes.
c) And (4) performing iterative calculation on the electric field and the oxygen.
d) And (5) performing cumulative calculation on a plurality of time steps to obtain the bolt corrosion development process in the time period T.
Further, the diffusion equation of chloride ions is characterized by formula (1):
in the formula, C Cl Is the concentration of chloride ions in concrete, kg/m 3 。D Cl Is the diffusion coefficient of chloride ions in concrete, m 2 /s。
The technical effects of the invention are undoubted: the problem that the bolt corrosion detection and monitoring in the concrete are difficult is solved. The chloride ion diffusion and the stud corrosion in the concrete are analyzed in a coupling mode, numerical simulation of the stud corrosion process in the service period of the combined structure is achieved, the corrosion process is given, and the method can be used for analyzing and evaluating the steel-concrete combined structure.
Drawings
FIG. 1 is a flow chart of rust development calculation within an evaluation period T;
FIG. 2 is a flow chart of calculation of chloride diffusion-induced blunting;
FIG. 3 is a graph showing the path of chloride ions entering the concrete to the surface of the stud;
FIG. 4 is a schematic view of a modeled region of a peg in example 5;
FIG. 5 is a schematic illustration of a concrete analysis area and studs;
FIG. 6 is a finite element model of stud corrosion calculation;
FIG. 7 illustrates the intrusion of chloride ions from the top surface of a concrete slab;
FIG. 8 is a cloud chart I of the corrosion state and corrosion amount of the stud;
FIG. 9 illustrates the intrusion of chloride ions from the underside of a concrete slab;
FIG. 10 is a cloud chart II of the bolt corrosion shape and corrosion depth;
FIG. 11 is a cloud III of the corrosion morphology and corrosion depth of the peg.
Detailed Description
The present invention is further illustrated by the following examples, but it should not be construed that the scope of the above-described subject matter is limited to the following examples. Various substitutions and alterations can be made without departing from the technical idea of the invention and the scope of the invention is covered by the present invention according to the common technical knowledge and the conventional means in the field.
Example 1:
the embodiment provides a numerical method for bolt corrosion simulation, which comprises the following steps:
1) intercepting a modeling area of any single stud in the steel-concrete composite beam bridge to be analyzed, and specifying geometric parameters of the modeling area. In the modeling area, concrete is represented by a cuboid area, and the studs are represented by a stepped rotary body area. The step-shaped revolving body comprises two cylinders which are overlapped up and down. Six faces of the cuboid are concrete boundaries, and five faces of the stepped rotary body are stud boundaries. The studs are arranged in the concrete, the area between the concrete boundary and the stud boundary being the concrete filling area.
2) And (4) constructing a concrete and stud finite element model and carrying out mesh division.
4) A pin corrosion numerical simulation finite element program is compiled based on an electrochemical principle.
5) The evaluation period T is divided into a plurality of calculation steps in time steps Δ T. And (4) running a bolt corrosion numerical simulation finite element program, and calculating to obtain the bolt corrosion condition in the evaluation period T.
And 5.1) carrying out judgment on the bolt blunt-off until anode nodes appear on the surface of the bolt. Steel in concrete produces a passive film in an alkaline environment, and the destruction of the passive film depends on the chloride threshold of the concrete, i.e. the chloride content required for the steel to break down locally and rust. When the concentration of chloride ions on the surface of the stud reaches the derotation threshold value, the stud begins to rust. The actual corrosion condition of the steel in the concrete is that if a certain position starts corrosion once and cannot stop, namely, once the node on the surface of the steel is blunt, the node is an anode in the whole numerical simulation calculation process. The calculation flow is shown in fig. 2 based on the judgment of chloride ion diffusion and blunt-removal.
5.11) obtaining t from the numerical simulation of chloride ion diffusion i The time of peg surface chloride ion concentration.
5.12) performing blunt judgment on all nodes on the surface of the stud. And when the chloride ion concentration at the node is less than the chloride ion inactivation threshold, the node is judged to be a cathode node. And when the chloride ion concentration at the node is greater than or equal to the blunt threshold, determining that the node is an anode node. When the pin surface has anode nodes, the pin surface is blunt.
5.13) repeating the steps 5.11) and 5.12) to calculate the next time step until the surface of the pin has anode nodes.
5.2) referring to FIG. 1, a simulation of the development of stud corrosion was performed.
5.21) obtaining the surface chloride ion concentration of the stud at the t moment by numerical simulation of chloride ion diffusion.
5.22) obtaining the cathode and anode point distribution of the surface of the stud. And when the chloride ion concentration at the node is less than the chloride ion inactivation threshold, the node is judged as a cathode node. And when the chloride ion concentration at the node is greater than or equal to the blunt threshold, determining that the node is an anode node.
5.23) iteratively calculating the corrosion rate and the corrosion amount in the time step of delta t. After iterative convergence, rust in the next Δ t time step is calculated. And superposing the corrosion amount of each delta t time step to obtain the overall corrosion state.
5.24) cumulative calculations are performed for each time step until the final time T is calculated.
6) And (5) carrying out visualization processing on the corrosion condition obtained in the step 5) to obtain the corrosion form and corrosion amount cloud chart of the stud.
It is noted that in this example, t is obtained by numerical simulation of chloride ion diffusion based on the finite element method i Time of day orthe chloride ion concentration on the surface of the peg at time t. The chloride ion diffusion equation is characterized by the mathematical expression of Fick's law:
in the formula, C Cl Is the concentration of chloride ions in concrete, kg/m 3 。D Cl Is the diffusion coefficient of chloride ions in concrete, m 2 /s。
The embodiment provides a numerical simulation mode based on an electrochemical reaction principle, and the corrosion form of the stud in the steel-concrete combined structure is intuitively analyzed, so that the time-varying bearing capacity degradation analysis of the stud under the corrosion condition can be carried out.
Example 2:
the main steps of this embodiment are the same as those of embodiment 1, wherein, in step 2), tetrahedral or hexahedral mesh units are adopted to mesh the finite element model.
Example 3:
the main steps of this example are the same as example 1, wherein, before step 5), there is a relevant step of determining the invasion path of chloride ions. The invasion of chloride ions in the external environment has a great influence on the corrosion of the stud in the steel-concrete combined structure. Referring to fig. 3, the intrusion paths of chloride ions are divided into two types in this embodiment: the first is the intrusion of chloride ions from the concrete ceiling and the second is the intrusion of chloride ions from the concrete floor. In the calculation of the chloride ion diffusion, the concrete is considered to be homogeneous to the chloride ion diffusion, and the influence of the longitudinal crack of the concrete top plate on the chloride ion diffusion is not considered, and the influence of the interface damage of the section steel and the concrete and the like on the chloride ion diffusion is not considered.
Example 4:
the main steps of this example are the same as example 1, wherein the cathode and anode point distribution in this region was obtained by judgment of the dulling of the metal surface. On the basis, the corrosion development of the concrete steel is calculated, and the corrosion rate and the corrosion amount in the time step of delta t are calculated in an iterative manner. When calculating the corrosion rate in Δ t, t 1 Oxygen concentration C at the moment 1 The average corrosion rate and corrosion amount within delta t and t are obtained by the iterative calculation of the last step and are calculated by an electric field-oxygen balance program 2 Oxygen concentration profile C at time 2 . And calculating the corrosion of the next delta t after iterative convergence. And the corrosion amount of each delta t (a time step) is superposed to obtain the overall corrosion state. The rust calculation procedure within a single time step is divided into three sub-procedures: an electric field calculation subprogram, an oxygen transmission subprogram and a steel corrosion calculation subprogram. Each subprogram is divided into several subprograms.
The rust calculation flow of a single time step comprises the following steps:
a) electric field calculation:
the method comprises the steps of firstly inputting the initial current density of a cathode and an anode, calculating the potential of a cathode and anode node, then calculating the electric field distribution in concrete, and further calculating the actual current density of the node. The charge conservation equation is shown in the formula (2), the anode potential equation is shown in the formula (3), and the cathode potential equation is shown in the formula (4):
in the formula phi a Is the potential, i is the vector of the current density (A/m) 2 )，σ(S w ,p con ) Is the electrical conductivity of the concrete (depending on the concrete porosity and pore solution saturation). S w Saturation of the concrete void solution, p con Is the porosity, σ (S), of the concrete w ,p con ) And S w And p con And (6) correlating.
In the formula phi a Is the potential of the anode, i a Is the vector of the anodic current density (A/m) 2 )，i 0a (A/m 2 ) Exchange current density for anodic reaction, phi 0a (V) is the anode equilibrium potential, beta a (V/dec) is Tafel slope of anodic reaction, i 0a 、Φ 0a 、β a The three parameters are related to electrochemistry and are taken according to a related method.
In the formula phi c Is the potential of the cathode, i c Is vector of cathode current density (A/m) 2 )，i 0c (A/m 2 ) Exchange current density for cathodic reaction, phi 0c (V) is the cathode equilibrium potential, beta c (V/dec) is Tafel slope of cathode reaction, i 0c 、Φ 0c 、β c The three parameters are related to electrochemistry and are taken according to a related method. C 0 As the oxygen concentration of the cathode, C 0b Is the oxygen concentration at the concrete boundary.
b) Oxygen transmission calculation and steel corrosion calculation:
the method comprises the steps of firstly determining the oxygen consumption rate of a cathode node and an anode node, using the oxygen consumption rate as one boundary condition of oxygen transmission, inputting the other boundary condition of oxygen (oxygen in an external environment enters concrete), meanwhile, having a certain initial oxygen concentration in the concrete, then calculating the diffusion of the oxygen in the concrete, obtaining the actual oxygen concentration of the cathode node and the anode node, and meanwhile, corroding the consumed oxygen by a bolt. The oxygen diffusion equation is shown in equation (5), the anode oxygen consumption equation is shown in equation (6), and the cathode oxygen consumption equation is shown in equation (7):
in the formula (I), the compound is shown in the specification,
k c ＝8.29×10 -8 kg/C n is the normal direction of the anode or cathode surface, C o The oxygen concentration (kg/m) in the concrete pore solution 3 )；D o (S w ,p con ) Is the diffusion coefficient (m) of oxygen in the concrete void solution 2 /s)，S w Saturation of the concrete void solution, p con Porosity of concrete, D o (S w ,p con ) And S w And p con And (4) correlating.
The anodic reaction is an oxidation process, steel is dissolved into a concrete void solution, and electrons are lost to become ferrous ions, as shown in formula (8). The cathode reaction is a reduction process, and oxygen which is externally diffused into the concrete obtains electrons and generates hydroxyl ions with water. Oxygen gas which is externally diffused into the concrete is subjected to cathode reaction, and dissolved oxygen is reduced to form hydroxide ions, as shown in a formula (9). The ferrous ions at the anode and the hydroxyl ion products at the cathode combine to form the unstable oxide ferrous hydroxide, as shown in equation (10). The ferrous hydroxide reacts with oxygen and water to produce ferric hydroxide, as shown in formula (11).
2Fe→2Fe 2+ +4e - (8)
2H 2 O+O 2 +4e - →4OH - (9)
2Fe 2+ +4OH - →2Fe(OH) 2 (10)
c) Iterative calculation of electric field and oxygen (convergence decision):
and (3) calculating residual errors of the current density and the oxygen concentration, namely the difference between the actual current density and the initial current density and the difference between the actual oxygen concentration and the initial oxygen concentration, finishing the calculation if the residual errors meet the preset tolerance, and repeating the iteration steps of the first step, the second step and the third step if the residual errors do not meet the preset tolerance.
d) Multiple time step cumulative calculation:
the add cycle section calculates the overall rust development. And performing accumulated calculation on each time step until the final time T is calculated, and finishing the calculation. For the peg rust development process within the 0-T period.
Example 5:
in the embodiment, a certain steel-concrete combined beam bridge in coastal areas of east China is taken as a research object, and the development of stud corrosion in a cross beam of the bridge is simulated and researched. In the specific implementation, the top and bottom surfaces of the concrete slab are considered to be exposed surfaces, respectively. The numerical method for simulating the corrosion of the stud comprises the following steps:
1) intercepting a modeling area of any single stud in the steel-concrete composite beam bridge to be analyzed, and specifying geometric parameters of the modeling area. In the modeling area, concrete is represented by a cuboid area, and the studs are represented by a stepped rotary body area. The step-shaped revolving body comprises two cylinders which are overlapped up and down. Six faces of the cuboid are concrete boundaries, and five faces of the stepped rotary body are stud boundaries. The studs are arranged in the concrete, the area between the concrete boundary and the stud boundary being the concrete filling area.
Referring to fig. 4, because the volume of the concrete slab is too large, only the concrete within 100mm from the upper flange of the steel beam is intercepted, and the influence of the interception on the calculation result is reduced to the maximum extent. The shaded areas in fig. 4a, 4b and 4c are the single-pin modeling areas.
2) And constructing a concrete and stud finite element model and carrying out grid division. Only concrete and studs are considered during modeling, and steel beam flanges are not considered. The concrete section taken was a rectangular parallelepiped of 300X 200X 100(mm X mm), the peg having a diameter of 16mm and a length of 100 mm. The concrete analysis area size and peg are shown in fig. 5. The concrete analysis area and the pin finite element model are shown in fig. 6.
4) A pin corrosion numerical simulation finite element program is compiled based on an electrochemical principle.
5) Determining the invasion path of chloride ions. The invasion of chloride ions in the external environment has a great influence on the corrosion of the stud in the steel-concrete composite structure. The method is implemented by dividing the intrusion path of the chloride ions into two types: the first is the intrusion of chloride ions from the concrete ceiling and the second is the intrusion of chloride ions from the concrete floor. In the calculation of the chloride ion diffusion, the concrete is considered to be homogeneous to the chloride ion diffusion, and the influence of the longitudinal cracks of the concrete top plate on the chloride ion diffusion is not considered, and the influence of the interface damage of the section steel and the concrete and the like on the chloride ion diffusion is not considered.
6) The evaluation period T is divided into a plurality of calculation steps in time steps Δ T. And (4) running a bolt corrosion numerical simulation finite element program, and calculating to obtain the bolt corrosion condition in the evaluation period T.
6.1) carrying out judgment on the bolt blunt until anode nodes appear on the surface of the bolt. Steel in concrete produces a passive film in an alkaline environment, and the destruction of the passive film depends on the chloride threshold of the concrete, i.e. the chloride content required for the steel to break down locally and rust. When the concentration of chloride ions on the surface of the stud reaches the derotation threshold value, the stud begins to rust. The actual corrosion condition of the steel in the concrete is that if a certain position starts corrosion once and cannot stop, namely, once the node on the surface of the steel is blunt, the node is an anode in the whole numerical simulation calculation process. The calculation flow is shown in fig. 2 based on the judgment of chloride ion diffusion and blunt-removal.
6.11) obtaining the concentration of the chlorine ions on the surface of the stud at the time ti through numerical simulation of chlorine ion diffusion.
6.12) performing blunt judgment on all nodes on the surface of the pin. And when the chloride ion concentration at the node is less than the chloride ion inactivation threshold, the node is judged as a cathode node. And when the chloride ion concentration at the node is greater than or equal to the blunt threshold, determining that the node is an anode node. When the pin surface has anode nodes, the pin surface is blunt.
6.13) repeating the steps 6.11) and 6.12) to calculate the next time step until the pin surface has an anodic node.
6.2) referring to fig. 1, a simulation of the development of peg corrosion was performed.
6.21) obtaining the surface chloride ion concentration of the stud at the time t by numerical simulation of chloride ion diffusion.
6.22) obtaining the cathode and anode point distribution of the surface of the stud. And when the chloride ion concentration at the node is less than the chloride ion inactivation threshold, the node is judged to be a cathode node. And when the chloride ion concentration at the node is greater than or equal to the blunt threshold, determining that the node is an anode node.
6.23) iteratively calculating the corrosion rate and the corrosion amount in the time step of delta t. After iterative convergence, rust in the next time step of Δ t is calculated. And superposing the corrosion amount of each delta t time step to obtain the overall corrosion state.
6.24) cumulative calculations are performed for each time step until the final time T is calculated.
7) And (4) carrying out visualization processing on the corrosion condition obtained in the step 6) to obtain the corrosion form and corrosion amount cloud chart of the stud.
It should be noted that, in this embodiment, the calculation result of the concrete slab top surface as the exposed surface is as follows:
the time step is 1 month, and the calculation time length is 100 years. The concentrations of the chloride ions and the oxygen, the diffusion coefficient and the conductivity of the concrete are evaluated according to a correlation formula. Regardless of the slab cracking, the chloride ion boundary conditions are shown in fig. 7. Calculating the concrete and the pin intercepting areas, extracting the corrosion amount of the pin in 20 years, 30 years, 40 years, 50 years, 60 years, 70 years, 80 years, 90 years and 100 years, and visualizing the corrosion result in a pin model. The corrosion morphology and the corrosion cloud pattern of the stud when chloride ions intrude from the top surface are shown in fig. 8.
In this embodiment, the calculation result of the concrete slab bottom surface as an exposed surface is as follows:
the time step is 1 month and the calculation time is 100 years. The chloride ion and oxygen concentrations, diffusion coefficients, and concrete conductivity were the same as for the roof intrusion, and the chloride ion boundary conditions, regardless of concrete cracks, are shown in fig. 9. Calculating the intercepted areas of the concrete and the studs, extracting the steel bar corrosion amount in the 25 th year, the 30 th year, the 40 th year, the 50 th year, the 60 th year, the 70 th year, the 80 th year, the 90 th year and the 100 th year, and carrying out visualization processing on the corrosion result in a steel bar model to obtain the stud corrosion form and a corrosion amount cloud chart. Fig. 10 and 11 are graphs (unit: mm) of the rust results of the peg, viewed from the front and the side, respectively.
Claims (5)
1. A numerical method for simulating bolt corrosion is characterized by comprising the following steps:
1) intercepting a modeling area of any single stud in the steel-concrete composite beam bridge to be analyzed, and specifying geometric parameters of the modeling area; in the modeling area, concrete is represented by a cuboid area, and the studs are represented by a stepped revolving body area; the stepped rotary body comprises two cylinders which are overlapped up and down; six surfaces of the cuboid are concrete boundaries, and five surfaces of the stepped rotary body are stud boundaries; the stud is arranged in the concrete, and the area between the concrete boundary and the stud boundary is a concrete filling area;
2) constructing a concrete and stud finite element model, and carrying out grid division;
4) programming a stud corrosion numerical simulation finite element program based on an electrochemical principle;
5) dividing the evaluation period T into a plurality of calculation steps according to the time step delta T; running a bolt corrosion numerical simulation finite element program, and calculating to obtain the bolt corrosion condition in the evaluation period T;
5.1) performing judgment on bolt blunt-off until anode nodes appear on the surface of the bolt;
5.2) simulating the development of the stud corrosion; the step 5.2) specifically comprises the following steps:
5.21) obtaining the concentration of the chloride ions on the surface of the stud at the time t by the chloride ion diffusion numerical simulation;
5.22) obtaining the cathode and anode point distribution of the stud surface; when the chloride ion concentration at the node is less than the chloride ion inactivation threshold, the node is judged to be a cathode node; when the chloride ion concentration at the node is greater than or equal to the blunt threshold, the node is judged to be an anode node;
5.23) iteratively calculating the corrosion rate and the corrosion amount in the time step of delta t; calculating corrosion in the next time step of delta t after iterative convergence; superposing the corrosion amount of each delta t time step to obtain the overall corrosion state; in step 5.23), the corrosion calculation flow of a single time step comprises the following steps:
a) calculating an electric field, and calculating the actual current density of the node;
b) oxygen transmission calculation is carried out to obtain the actual oxygen concentration of the cathode and anode nodes;
c) iterative calculation of electric field and oxygen;
d) performing accumulated calculation on a plurality of time steps to obtain the bolt corrosion development process in the time period T;
5.24) carrying out cumulative calculation on each time step until the final time T is calculated;
6) and (5) carrying out visualization processing on the corrosion condition obtained in the step 5) to obtain the corrosion form and corrosion amount cloud chart of the stud.
2. The numerical method for bolt corrosion simulation according to claim 1, wherein the method comprises the following steps: in the step 2), meshing is carried out on the finite element model by using tetrahedral or hexahedral mesh units.
3. A numerical method of bolt corrosion simulation according to claim 1, characterized in that: before step 5), the method also has a relevant step of determining the invasion path of the chloride ions.
4. A numerical method for bolt corrosion simulation according to claim 1, wherein the step 5.1) specifically comprises the steps of:
5.11) obtaining t from the numerical simulation of chloride ion diffusion i The concentration of chloride ions on the surface of the stud at any moment;
5.12) performing blunt judgment on all nodes on the surface of the stud; when the concentration of chloride ions at the node is less than a chloride ion inactivation threshold value, the node is judged to be a cathode node; when the chloride ion concentration at the node is greater than or equal to the blunt threshold, the node is judged to be an anode node; when the surface of the stud has an anode node, the surface of the stud is subjected to blunt removal;
5.13) repeating the steps 5.11) and 5.12) to calculate the next time step until the surface of the pin has anode nodes.
5. The numerical method for bolt corrosion simulation according to claim 4, wherein the diffusion equation of chloride ions is characterized by the following formula (1):
in the formula, C cl Is the concentration of chloride ions in concrete, kg/m 3 ；D Cl Is the diffusion coefficient of chloride ions in concrete, m 2 /s。
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| CN101762453A (en) * | 2010-01-15 | 2010-06-30 | 浙江大学 | Accelerated test method of non-uniform corrosion in inbuilt electrode simulation concrete |
| CN108416108A (en) * | 2018-02-05 | 2018-08-17 | 东南大学 | Finite element modeling method for the design of steel-concrete composite beam Welded-Stud Conectors |
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| CN101762453A (en) * | 2010-01-15 | 2010-06-30 | 浙江大学 | Accelerated test method of non-uniform corrosion in inbuilt electrode simulation concrete |
| CN108416108A (en) * | 2018-02-05 | 2018-08-17 | 东南大学 | Finite element modeling method for the design of steel-concrete composite beam Welded-Stud Conectors |
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