Method for evaluating corrosion degree of bridge corrosion cable steel wire

Abstract

The invention discloses a method for evaluating the corrosion degree of a bridge corrosion cable steel wire, and the method comprises the steps: carrying out the three-dimensional scanning of a to-be-evaluated corrosion cable steel wire corrosion surface, and carrying out the standardization processing of the appearance point cloud data of the corrosion surface, calculating by means of Matlab software to obtain the weakest cross-sectional area, the average cross-sectional area, the weakest cross-sectional loss rate, the average cross-sectional loss rate, the volume loss rate and the like of the steel wires with different corrosion degrees; geomagic and Design X software is utilized to flatten the surface of the rusted steel wire, a box counting method is adopted to calculate the fractal dimension of the corroded surface of the rusted steel wire, and the corrosion degree of the rusted cable steel wire is comprehensively judged according to the calculated evaluation indexes such as the weakest cross section loss rate, the average cross section loss rate, the volume loss rate and the fractal dimension. According to the method, the corrosion degree evaluation index of the rusted cable steel wire is calculated based on the real corrosion surface, so that the calculation structure is more accurate, the calculation efficiency is greatly improved, and efficient evaluation of the corrosion degree of the rusted cable steel wire is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of durability and safety evaluation of bridge steel structures in corrosive environments, and in particular relates to a method for evaluating the corrosion degree of rusted cable steel wires of a bridge. Background Art

[0002] As a key component connecting the bridge deck system and the arch rib, the cable transfers the constant and live loads of the bridge deck system to the arch rib, and is the lifeline of a large-span cable-bearing bridge. However, bridge cables have a long service life and are exposed to the natural environment, subject to environmental erosion. Corrosion causes the loss of geometric cross-section and performance degradation of the steel wire inside the cable, resulting in a significant reduction in its durability and bearing capacity, which directly affects the safe operation of the entire bridge structure. Therefore, how to accurately and efficiently evaluate the corrosion degree of rusted cable wires and prevent the occurrence of engineering accidents is a major problem faced by engineering and technical personnel.

[0003] At present, in engineering applications, the method for judging the corrosion degree of bridge cable steel wires only relies on naked eye observation and referring to the corresponding corrosion grades in the specifications to determine the current corrosion degree of the steel wires. However, this method is highly subjective and cannot quantitatively describe the corrosion degree of the steel wires.

[0004] In actual research, domestic and foreign scholars mostly use weighing or vernier calipers to determine the weight loss rate and thickness loss of steel wires, so as to determine the degree of corrosion of steel wires. However, the actual corroded steel wires have local corrosion problems, and the weight loss rate cannot reflect the local corrosion degree of steel wires. Secondly, the error of measuring thickness loss with vernier calipers is increased, and the measurement efficiency is low if a large number of steel wires are involved, and it cannot reflect the degree of change of the overall corrosion surface morphology of the steel wires. In view of this, it is urgent to provide a corrosion degree evaluation method for corroded cable steel wires that takes into account the corrosion surface morphology. Summary of the invention

[0005] To solve the above problems, the present invention discloses a method for evaluating the corrosion degree of corroded cable steel wires of bridges. Based on the real corrosion surface, the corrosion degree evaluation index of the corroded cable steel wires is calculated, which not only makes the calculation structure more accurate, but also greatly improves the calculation efficiency, thereby realizing efficient evaluation of the corrosion degree of the corroded cable steel wires.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for evaluating the corrosion degree of bridge corroded cable wires comprises the following steps:

[0008] Step 1: Perform a three-dimensional scan on the corroded surface of the rusted cable wire to be evaluated;

[0009] Step 2: Standardize the point cloud data of the corroded surface morphology to obtain a standardized model of the corroded cable wire;

[0010] Step 3: Based on the obtained standardized model of the corroded cable steel wire, the weakest cross-sectional area, average cross-sectional area, weakest cross-sectional loss rate, average cross-sectional loss rate, volume loss rate and corrosion depth of the steel wires with different corrosion degrees are calculated with the help of Matlab software;

[0011] Step 4: At the same time, Geomagic and Design X software are used to flatten the surface of the corroded steel wire to obtain a flattened corroded cable steel wire model;

[0012] Step 5: Based on the flattened corroded cable wire model, the fractal dimension of the corroded surface of the corroded steel wire is calculated by using the box counting method;

[0013] Step 6, repeat steps 1 to 5 to calculate the evaluation index values ​​of cable steel wires with different corrosion degrees;

[0014] Step 7: Comprehensively determine the corrosion degree of the differently corroded cable wires based on the weakest section loss rate, average section loss rate, volume loss rate, corrosion depth, fractal dimension and other evaluation indicators calculated above.

[0015] Furthermore, in step 1, in the three-dimensional scanning, in order to avoid the influence of the surface quality of the specimen on the scanning effect, a layer of developer needs to be sprayed on the surface of the object. Secondly, in order to obtain the point cloud data of the surface morphology of the corroded steel wire, multiple and multi-angle scans are required. Finally, the point clouds at different angles are converted into the same coordinate system through the reference point.

[0016] Furthermore, in step 2, the point cloud data of the rusted surface morphology is standardized as follows:

[0017] The 3D scanning point cloud data of the surface of the corroded cable wire is divided into upper and lower parts. The above 3D scanning point cloud data is imported into the surf software, the coordinate spacing is determined according to the actual scanning accuracy, and the upper and lower surface data of the corroded steel wire are matrix-aligned according to the Kriging method.

[0018] Furthermore, in step 3, the evaluation index of the corroded cable wire is calculated, and the numerical intervals along the X-axis and Y-axis of the specimen are consistent with the scanning accuracy.

[0019] Furthermore, in step 4, the surface of the corroded steel wire is flattened using Geomagic and Design X software, as follows:

[0020] The 3D scanning point cloud data was imported into Geomagic software for denoising, coloring, packaging and other processing to obtain the geometric model of the corroded cable wire. The obtained geometric model was then imported into Design X software for segmentation, alignment and definition of the central axis, and then flattened to obtain the plane model of the corroded cable wire.

[0021] Furthermore, in step 5, the fractal dimension of the corrosion surface of the rusted steel wire is calculated using the box counting method, as follows:

[0022] S1. According to the scanning accuracy η, the corrosion domain of the flattened rusted cable wire model is divided into D / η*L / η small areas (D is the width of the corrosion area, L is the length of the corrosion area), recorded as M(D / η*L / η) j ;

[0023] S2, the size is q i *q i *q i The number of squares required to cover any small area is Q i (M(D / η*L / η) j ), Q i (M(D / η*L / η) j ) and the height difference △Z of the area kj related;

[0024] S3, the sum of the number of squares required for all areas is the scale q i Next, the number of squares required to cover the weak section;

[0025] S4, repeating steps S1 to S3 to obtain the number of squares required to cover the weak section at different scales;

[0026] S5. According to the scale and the number of squares obtained above, and based on the logarithmic relationship between the two, the fractal dimension value of the corrosion surface of the rusted steel wire is obtained.

[0027] The beneficial effects of the present invention are:

[0028] The present invention provides a method for evaluating the degree of corrosion of a corroded cable steel wire, which realizes automatic acquisition of the corrosion surface morphology of the corroded cable steel wire through three-dimensional scanning; based on the three-dimensional scanning point cloud data, a standardized model of the corroded cable steel wire is obtained, thereby being able to efficiently and quickly calculate evaluation indicators such as the weakest cross-sectional area, average cross-sectional area, weakest cross-sectional loss rate, average cross-sectional loss rate and volume loss rate of steel wires with different degrees of corrosion; a plane model of the corroded cable steel wire is established, thereby proposing to use a box counting method to calculate the fractal dimension of the corrosion surface of the corroded steel wire, which can not only accurately consider the influence of the corrosion surface, but also realize the solution of the fractal dimension of complex surfaces. Solving the corrosion degree evaluation index of the corroded cable steel wire by the above method can lay a foundation for the subsequent evaluation of the residual mechanical properties of the steel wire. The present invention can further enrich the performance evaluation in the field of durability and safety of bridge steel structure engineering, and provide a technical basis for engineering and technical personnel engaged in the detection, evaluation and reinforcement of existing engineering structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the technical solution of the present invention;

[0030] Figure 2 This is the scanning result of the surface morphology of the corroded cable wire;

[0031] Figure 3 It is the standardized treatment and result diagram of the surface of rusted cable wire; among them, Figure 3 (a) is a diagram showing the standardized alignment of the upper and lower surfaces of the corroded cable wire; Figure 3 (b) is the result of the alignment treatment of the upper and lower surfaces of the corroded cable wire;

[0032] Figure 4 It is the calculation diagram of the area and depth of different cross-section positions of the rusted cable wire; among them, Figure 4 (a) is a schematic diagram of the calculation of different cross-sectional positions of the corroded cable wire; Figure 4 (b) is a schematic diagram of the calculation method of the cross-sectional area of ​​the corroded cable wire; Figure 4 (c) is a schematic diagram of the calculation of the depth of the corroded cable wire; Figure 4 (d) is a diagram showing the method for calculating the depth of corroded cable wires;

[0033] Figure 5 This is a flattening diagram of the rusted cable wire; Figure 5 (a) is a diagram showing the flattening process of the corroded cable wire; Figure 5 (b) is the flattening result of the corroded cable wire;

[0034] Figure 6 is the calculation and result diagram of the fractal dimension of the corroded cable wire; among them, Figure 6 (a) is a schematic diagram of the calculation method of the fractal dimension of corroded cable wire; Figure 6(a) is the calculation result of fractal dimension of corroded cable wire. DETAILED DESCRIPTION

[0035] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0036] like Figure 1 As shown, a method for evaluating the corrosion degree of a corroded cable steel wire of the present invention comprises: performing three-dimensional scanning on the corroded surface of the corroded cable steel wire to be evaluated, performing standardization processing on the point cloud data of the morphology of the corroded surface, and calculating the weakest cross-sectional area, average cross-sectional area, weakest cross-sectional loss rate, average cross-sectional loss rate, volume loss rate and corrosion depth of steel wires with different corrosion degrees by using Matlab software on the basis of the standardized model; flattening the surface of the corroded steel wire by using Geomagic and Design X software, calculating the fractal dimension of the corroded surface of the corroded steel wire by using the box counting method, and comprehensively determining the corrosion degree of the corroded cable steel wire according to the evaluation indicators such as the weakest cross-sectional loss rate, average cross-sectional loss rate, volume loss rate, corrosion depth, fractal dimension, etc. calculated above, so as to realize accurate and efficient evaluation of the corrosion degree of the corroded cable steel wire.

[0037] Example

[0038] The method for evaluating the corrosion degree of a rusted cable steel wire described in this embodiment specifically comprises the following steps:

[0039] Step 1: Perform multiple, multi-angle scanning of the corroded surface of the rusted cable wire to be evaluated. Scan it at angle 1 and angle 2 respectively. The data coordinates corresponding to the data at different angles are angle 1 and angle 2. Assume that there is a point P in space. The coordinates in the point cloud data obtained at two angles are marked as P1 (x p 1 ,y p 1 ,z p 1 ) and P2(x p 2 ,y p 2 ,z p 2 ). By rotation and translation, the point coordinate P2 obtained by angle 2 is converted to the point coordinate P1 obtained by angle 1. The conversion formula is as follows:

[0040]

[0041] Where x0, y0 and z0 are three translation parameters, three-dimensional vectors; a11, a12, a13, a21, a22, a23, a31, a32 and a33 are nine direction cosines, third-order matrices.

[0042] According to the 3D scanning results, the scanned point cloud data was standardized, and the upper and lower surface data of the rusted steel wire were matrix-aligned using the surf software according to the kriging method.

[0043] Step 2: Based on the obtained standardized model of the corroded cable steel wire, the weakest cross-sectional area, average cross-sectional area, weakest cross-sectional loss rate, average cross-sectional loss rate, volume loss rate, corrosion depth and other evaluation indicators of the steel wires with different corrosion degrees are calculated with the help of Matlab software;

[0044] The specific calculation formulas for the weakest cross-sectional area, average cross-sectional area, weakest cross-sectional loss rate, average cross-sectional loss rate and volume loss rate of the steel wires with different corrosion degrees are as follows:

[0045]

[0046] In the formula, S min is the weakest cross-sectional area, S X is the cross-sectional area at position X along the length of the wire, Z is the cross-sectional height at position j, S ave is the average cross-sectional area, S0 is the original cross-sectional area, ω min is the weakest section loss rate, ω ave is the average cross-sectional loss rate, V is the volume loss rate, and V0 is the original volume;

[0047] The corrosion depth calculation is to use the original center coordinate as the origin to establish the coordinate axis, and establish different angle planes (such as plane 1 and plane 2) through the center point. The line connecting the intersection of the plane and the specimen is the residual thickness at different positions of the specimen (such as d AB d CD ). The calculation expressions of maximum corrosion depth, average corrosion depth and standard deviation are as follows:

[0048] h max =h0-d min (7)

[0049]

[0050] In the formula, h max is the maximum corrosion depth, h0 is the original thickness of the high-strength steel wire, d min is the minimum diameter of the corroded steel wire, d ij is the diameter of the rusted wire at the i-th section and the plane angle is j, A ijY is the Y coordinate value of point A at position ij, A ij Z is the Z coordinate value of point A at position ij, h ave is the average corrosion depth, h st is the standard deviation of corrosion depth.

[0051] Step 3: Use Geomagic and Design X software to flatten the surface of the rusted steel wire, as follows:

[0052] The 3D scanning point cloud data was imported into Geomagic software for denoising, coloring, packaging and other processing to obtain the geometric model of the corroded cable wire. The obtained geometric model was then imported into Design X software for segmentation, alignment and definition of the central axis, and then flattened to obtain the plane model of the corroded cable wire.

[0053] Step 4: Use the box counting method to calculate the fractal dimension of the corrosion surface of the rusted steel wire, as follows:

[0054] S1. According to the scanning accuracy η, the corrosion domain of the flattened rusted cable wire model is divided into D / η*L / η small areas (D is the width of the corrosion area, L is the length of the corrosion area), recorded as M(D / η*L / η) j ;

[0055] S2, the size is q i *q i *q i The number of squares required to cover any small area is Q i (M(D / η*L / η) j ), Q i (M(D / η*L / η) j ) and the height difference △Z of the area kj The specific formula is as follows:

[0056]

[0057] S3, the sum of the number of squares required for all areas is the scale q i Next, the number of squares required to cover the weak section;

[0058] S4, repeating steps S1 to S3 to obtain the number of squares required to cover the weak section at different scales;

[0059] Table 2 Fractal calculation results of corrosion surface of a corroded cable wire

[0060] q 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Q 59601943 7450242 2207479 931280 476815 275934 173766 116410 81758

[0061] S5. According to the scale and the number of squares obtained above, and based on the logarithmic relationship between the two, the fractal dimension value of the corrosion surface of the rusted steel wire is obtained. The logarithmic relationship formula is as follows:

[0062]

[0063] In the formula, Q(q) is the number of squares, q is the scale, -D W is the slope (fractal dimension value), and lnw is the intercept.

[0064] It should be noted that the above content only illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A method for evaluating the corrosion degree of bridge cable wires, characterized in that: The following steps are involved: Step 1: Perform a three-dimensional scan on the corroded surface of the rusted cable wire to be evaluated; Step 2: Standardize the point cloud data of the corroded surface morphology to obtain a standardized model of the corroded cable wire; Step 3: Based on the obtained standardized model of corroded cable steel wire, the evaluation index of steel wires with different corrosion degrees is calculated with the help of Matlab software; Step 4: At the same time, Geomagic and Design X software are used to flatten the surface of the corroded steel wire to obtain a flattened corroded cable steel wire model; Step 5: Based on the flattened corroded cable wire model, the fractal dimension of the corroded surface of the corroded steel wire is calculated by using the box counting method; Step 6, repeat steps 1 to 5 to calculate the evaluation index values ​​of cable wires with different corrosion degrees; Step 7: Comprehensively determine the corrosion degree of the differently corroded cable wires based on the evaluation indicators calculated above.

2. A method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1, characterized in that: In step 1, during 3D scanning, in order to avoid the influence of the surface quality of the specimen on the scanning effect, a layer of developer needs to be sprayed on the surface of the object; secondly, in order to obtain the point cloud data of the surface morphology of the corroded steel wire, multiple and multi-angle scans are required; finally, the point clouds at different angles are converted into the same coordinate system through the reference point, and the conversion formula is as follows: In the formula, x0, y0 and z0 are three translation parameters, three-dimensional vectors; a 11 、a 12 、a 13 、a 21 、a 22 、a 23 、a 31 、a 32 and a 33 They are nine direction cosines and third-order matrices respectively.

3. The method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1 is characterized by: In step 2, the point cloud data of the rusted surface morphology is standardized as follows: The 3D scanning point cloud data of the surface of the corroded cable wire is divided into upper and lower parts. The above 3D scanning point cloud data is imported into the surf software, the coordinate spacing is determined according to the actual scanning accuracy, and the upper and lower surface data of the corroded steel wire are matrix-aligned according to the Kriging method.

4. The method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1 is characterized by: In step 3, the evaluation index of the corroded cable wire is calculated, and the numerical interval along the X-axis and Y-axis of the specimen is consistent with the scanning accuracy.

5. The method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1 is characterized by: The evaluation indicators described in step 3 include but are not limited to: the weakest cross-sectional area of ​​the steel wire, the average cross-sectional area, the weakest cross-sectional loss rate, the average cross-sectional loss rate, the volume loss rate and the corrosion depth; The specific calculation formulas for the weakest cross-sectional area, average cross-sectional area, weakest cross-sectional loss rate, average cross-sectional loss rate and volume loss rate of the steel wires with different degrees of corrosion are as follows: In the formula, S min is the weakest cross-sectional area, S X is the cross-sectional area at position X along the length of the wire, Z is the cross-sectional height at position j, S ave is the average cross-sectional area, S0 is the original cross-sectional area, ω min is the weakest section loss rate, ω ave is the average cross-sectional loss rate, V is the volume loss rate, and V0 is the original volume; The corrosion depth calculation is to use the original center coordinate as the origin to establish the coordinate axis, and establish planes of different angles through the center point. The line connecting the plane and the intersection of the specimen is the residual thickness at different positions of the specimen. The calculation expressions of the maximum corrosion depth, average corrosion depth and standard deviation are as follows: <h2 style=";text-align:left;direction:ltr">h<h2 style=";text-align:left;direction:ltr"> max <h2 style=";text-align:left;direction:ltr"> =h0-d<h2 style=";text-align:left;direction:ltr"> min <h2 style=";text-align:left;direction:ltr"> (7) In the formula, h max is the maximum corrosion depth, h0 is the original thickness of the high-strength steel wire, d min is the minimum diameter of the corroded steel wire, d ij is the diameter of the steel wire corresponding to the cross section at the i-th position of the corroded steel wire and the plane angle is j, A ij Y is the Y coordinate value of point A at position ij, A ij Z is the Z coordinate value of point A at position ij, h ave is the average corrosion depth, h st is the standard deviation of corrosion depth.

6. The method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1, characterized in that: In step 4, Geomagic and Design X software were used to flatten the surface of the rusted steel wire, as follows: S1. Import the 3D scanning point cloud data into Geomagic software for denoising, coloring and packaging to obtain the geometric model of the corroded cable wire; S2, importing the obtained geometric model into Design X software, segmenting it geometrically, and manually aligning it so that the center of the model is located at the center of the coordinate axis; S3, taking the plane coordinates XY and the plane XZ as standard planes, intersecting the two planes to establish a model development reference line; S4. Select the geometric model to be unfolded and select the established baseline to obtain a plane model of the corroded cable wire.

7. The method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1 is characterized by: In step 5, the fractal dimension of the corrosion surface of the rusted steel wire is calculated using the box counting method, as follows: S1. According to the scanning accuracy η, the corrosion domain of the flattened rusted cable wire model is divided into D / η*L / η small areas, where D is the width of the corrosion area and L is the length of the corrosion area, recorded as M(D / η*L / η) j ; S2, the size is q i *q i *q i The number of squares required to cover any small area is Q i (M(D / η*L / η) j ), Q i (M(D / η*L / η) j ) and the height difference △Z of the area kj The specific formula is as follows: S3, the sum of the number of squares required for all areas is the scale q i Next, the number of squares required to cover the weak section; S4, repeating steps S1 to S3 to obtain the number of squares required to cover the weak section at different scales; S5. According to the scale and the number of squares obtained above, and based on the logarithmic relationship between the two, the fractal dimension value of the corrosion surface of the rusted steel wire is obtained. The logarithmic relationship formula is as follows: In the formula, Q(q) is the number of squares, q is the scale, -D W is the slope and lnw is the intercept.

8. The method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1, characterized in that: The evaluation indicators described in step 7 include but are not limited to: the weakest section loss rate, the average section loss rate, the volume loss rate, the corrosion depth, and the fractal dimension.

9. The method for evaluating the corrosion degree of bridge corroded cable wires according to claim 1, characterized in that: In step 7, the corrosion degree of the steel wire is comprehensively determined, and the local and overall corrosion conditions of the corroded cable steel wire are defined by combining the calculated local corrosion degree index, overall corrosion degree index and surface roughness value, providing a reference index for subsequent cable steel wire maintenance and replacement.

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