Stay cable force identification method and system based on catenary fitting

Abstract

The invention relates to a stay cable force identification method and system based on catenary fitting. The method comprises the steps that three-dimensional coordinates of all measuring points on a stay cable are measured; according to the three-dimensional coordinates of all the measuring points, the two-dimensional coordinates of mapping points, corresponding to the positions of the center lines of the cable bodies of the stay cables, of all the measuring points in the vertical plane are obtained through conversion; carrying out catenary fitting on the two-dimensional coordinates of each mapping point by adopting a nonlinear optimization solution method to obtain linear parameters of the catenary; and obtaining the cable force of the stay cable at any position based on the linear parameters, the weight per unit length of the stay cable and the inclination angle of the stay cable at any position. The cable force identification method is based on catenary fitting, is completely consistent with the basic theory of a stay cable, utilizes the characteristic of large sag of an ultra-long cable, fits a catenary equation through data of a plurality of discrete measurement points, has good adaptability to measurement errors, improves the cable force identification precision, and improves the cable force identification accuracy. The method can effectively solve the problem that a conventional frequency method is not suitable for measuring the cable force of the super-long stay cable, and achieves the quick recognition of the cable force of the super-long stay cable.

Description

Technical Field

[0001] The present application relates to the technical field of cable-stayed bridge construction, and in particular to a method and system for identifying cable forces of a cable-stayed bridge based on catenary fitting. Background Art

[0002] During the construction and operation of cable-stayed bridges, cable tension testing is extremely important. The cable tension is not only directly related to the bridge line shape, but also the health of the cable force distribution greatly affects the service life of the cable. Therefore, for cable-stayed bridges, cable tension testing is directly related to the project quality.

[0003] Nowadays, the span of cable-stayed bridges continues to break records. For example, a bridge with a main span of 1,208 meters has a longest cable-stayed cable of more than 600 meters. Compared with small and medium-span cable-stayed bridges, cable force testing of ultra-long cables faces huge challenges.

[0004] The cable force test usually adopts the frequency method, which is based on the string vibration theory. Its basic principle is that there is a clear mapping relationship between the tension of a tensioned string and its natural frequency. For ultra-long cables, the shape of the cable under its own weight is a catenary with a large sag, which is significantly different from the basic assumptions of the string vibration theory.

[0005] The frequency method for measuring the tension of super-long stay cables has the following shortcomings:

[0006] (1) When using a vibration pickup to collect the natural frequency, only the vibration information of the end can be picked up. The end is greatly affected by interference from the cable guide, anchor, etc., and high requirements are placed on the selection of vibration mode.

[0007] (2) When using radar or laser methods to identify the natural frequency of the cable, the environment in which the ultra-long cable is located is complex and there is a certain complex modal effect. The identification effect is greatly affected by the environment.

[0008] (3) All super-long cables need to be installed with dampers. After the dampers are installed, the amplitude of the cables is greatly reduced and has a significant impact on the natural vibration mode. There is a large error in measuring the cable tension using the frequency method.

[0009] (4) The frequency method can only measure a nominal cable force and cannot determine the position of the cable force. For very long cables with significant sag effect, there is a large difference between the cable forces at the tower end and the beam end. The frequency method cannot measure the cable force at a specific position.

[0010] Therefore, for super-long stay cables, there are certain shortcomings in using the frequency method to measure cable tension. Summary of the invention

[0011] The embodiments of the present application provide a method and system for identifying the cable force of a stay cable based on catenary fitting, so as to solve the problem of large errors in measuring the cable force using the frequency method in the related art.

[0012] In a first aspect, a method for identifying the cable force of a stay cable based on catenary fitting is provided, which comprises the following steps:

[0013] Measure the three-dimensional coordinates of each measuring point on the inclined cable;

[0014] The three-dimensional coordinates of each measuring point are converted into the two-dimensional coordinates of the mapping point of each measuring point corresponding to the center line position of the cable body of the inclined cable in the vertical plane;

[0015] Using a nonlinear optimization solution algorithm to perform catenary fitting on the two-dimensional coordinates of each of the mapping points to obtain linear parameters of the catenary;

[0016] The cable force at any position of the cable is obtained based on the linear parameters, the weight per unit length of the cable and the inclination angle at any position of the cable.

[0017] In some embodiments, before measuring the three-dimensional coordinates of each measuring point on the stay cable, the method further includes:

[0018] A plurality of measuring points are set at certain intervals on the cable body of the inclined cable;

[0019] The stay cables are installed on the bridge.

[0020] In some embodiments, the distance between two adjacent measuring points is 10m to 50m.

[0021] In some embodiments, the number of the measuring points is at least 10.

[0022] In some embodiments, the two-dimensional coordinates of the mapping points of each measuring point corresponding to the centerline position of the cable body of the inclined cable are calculated from the three-dimensional coordinates of each measuring point, specifically including:

[0023] Convert the three-dimensional coordinates of each measuring point into the three-dimensional coordinates of a mapping point corresponding to the center line position of the cable body of the inclined cable;

[0024] The mapping points are rotated as a whole until all the mapping points are located in a vertical plane, so as to obtain the two-dimensional coordinates of the mapping points.

[0025] In some embodiments, the overall rotation of each of the mapping points specifically includes:

[0026] The three-dimensional coordinates of each of the mapping points are translated as a whole, so that one of the mapping points is translated to the origin of the coordinate system, to obtain the translated three-dimensional coordinates of each of the mapping points, and the mapping point is recorded as the first point;

[0027] The translated three-dimensional coordinates of each mapping point are rotated as a whole around the Z axis in the coordinate system until another mapping point is located in the XZ vertical plane or the YZ vertical plane, to obtain the rotated three-dimensional coordinates of each mapping point, and the mapping point is recorded as the second point;

[0028] The rotated three-dimensional coordinates of each of the mapping points are rotated as a whole around the line connecting the first point and the second point until the Y coordinate or the X coordinate in the rotated three-dimensional coordinates of all the mapping points is less than a preset value.

[0029] In some embodiments, the mapping points are sorted along the length direction of the cable body of the inclined cable, the first point is the first or the last of all the mapping points, and the second point is the last or the first of all the mapping points.

[0030] In some embodiments, the vertical plane is an XZ vertical plane in a coordinate system, and a nonlinear optimization algorithm is used to perform catenary fitting on the two-dimensional coordinates of each of the mapping points to obtain the linear parameters of the catenary, specifically including:

[0031] Construct the catenary equation:

[0032] Set the optimization target T:

[0033] Using nonlinear optimization solution algorithm, calculate the linear parameter α when the optimization target T takes the minimum value;

[0034] Where x0 and z0 are the catenary equations translated to the standard catenary equation The distance that the X-axis and Z-axis move when they coincide. The linear parameter α is the distance from the vertex of the curve to the abscissa axis in the standard equation of the catenary; i and z i is the two-dimensional coordinate of the mapping point corresponding to the i-th measuring point, and n is the total number of measuring points.

[0035] In some embodiments, the vertical plane is a YZ vertical plane in a coordinate system, and a nonlinear optimization solution algorithm is used to perform catenary fitting on the two-dimensional coordinates of each of the mapping points to obtain the linear parameters of the catenary, specifically including:

[0036] Construct the catenary equation:

[0037] Set the optimization target T:

[0038] Using nonlinear optimization solution algorithm, calculate the linear parameter α when the optimization target T takes the minimum value;

[0039] Where y0 and z0 are the catenary equations translated to the standard catenary equation The distance that the Y-axis and Z-axis move when they coincide. The linear parameter α is the distance from the vertex of the curve to the horizontal axis in the standard equation of the catenary; i and z i is the two-dimensional coordinate of the mapping point corresponding to the i-th measuring point, and n is the total number of measuring points.

[0040] In a second aspect, a cable force identification system based on catenary fitting is provided, which comprises:

[0041] The first module is used to receive the measured three-dimensional coordinates of each measuring point on the inclined cable;

[0042] The second module is used to convert the three-dimensional coordinates of each measuring point into the two-dimensional coordinates of the mapping point corresponding to the center line position of the cable body of each measuring point in the vertical plane;

[0043] The third module is used to perform catenary fitting on the two-dimensional coordinates of each of the mapping points using a nonlinear optimization solution algorithm to obtain the linear parameters of the catenary;

[0044] The fourth module is used to obtain the cable force at any position of the inclined cable based on the linear parameters, the unit length weight of the inclined cable and the inclination angle of the inclined cable at any position.

[0045] The beneficial effects of the technical solution provided by this application include:

[0046] Different from the conventional method based on string vibration theory, which is essentially different from the ultra-long cables, the cable force identification method provided in the embodiment of the present application is based on catenary fitting, which is completely consistent with the basic theory of inclined cables. It utilizes the large sag characteristic of ultra-long cables and fits the catenary equation through data from multiple discrete measuring points. It has good adaptability to measurement errors and improves the accuracy of cable force identification. It can be seen that the present application can effectively solve the inapplicability of conventional frequency methods for cable force measurement of ultra-long inclined cables and realize rapid identification of cable forces of ultra-long cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 A flow chart of a method for identifying the cable force of a stay cable based on catenary fitting provided in an embodiment of the present application;

[0049] Figure 2 This is a diagram showing the arrangement of measuring points on the cable body of the inclined cable provided in an embodiment of the present application.

[0050] In the figure: 1. Beam end anchor point; 2. Tower end anchor point; 3. Vibration damper; 4. Measuring point; 5. First point; 6. Second point. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0052] See also Figure 1 and Figure 2 As shown, the embodiment of the present application provides a method for identifying the cable force of a stay cable based on catenary fitting, which comprises the following steps:

[0053] 101: Measure the three-dimensional coordinates of each measuring point 4 on the inclined cable.

[0054] Specifically, when the cable-stayed cable is manufactured in a factory, a plurality of measuring points 4 are set at a certain interval on the cable body of the cable. The measuring points 4 should not be arranged near the ends of the cable body (including the beam end anchor point 1 and the tower end anchor point 2) and the vibration damper 3. By arranging the measuring points away from the cable ends and the damper, the large error at the ends of the cable and the adverse effects of the damper can be effectively avoided, and the cable force identification accuracy is significantly improved compared with the conventional method. Afterwards, the cable-stayed cable is installed on the bridge. During the cable force testing stage, the three-dimensional coordinates of the measuring points 4 are measured by a total station in a night environment, and the three-dimensional coordinates of each measuring point 4 are obtained in turn.

[0055] The distance between the measuring points 4 can be designed according to actual needs. For example, as an example, the distance between two adjacent measuring points 4 is 10m to 50m.

[0056] The number of the measuring points 4 can be designed according to actual needs. For example, as an example, the number n of the measuring points 4 is not less than 10, that is, the number of the measuring points 4 is at least 10.

[0057] 102: Convert the three-dimensional coordinates of each measuring point into the two-dimensional coordinates of the mapping point of each measuring point corresponding to the center line position of the cable body of the inclined cable in the vertical plane.

[0058] 103: Using a nonlinear optimization solution algorithm to perform catenary fitting on the two-dimensional coordinates of each of the mapping points to obtain linear parameters of the catenary.

[0059] 104: Based on the linear parameters, the unit length weight of the cable and the inclination angle of any position of the cable, the cable force at any position of the cable is obtained.

[0060] Different from the conventional method based on string vibration theory, which is essentially different from the ultra-long cables, the cable force identification method provided in the embodiment of the present application is based on catenary fitting, which is completely consistent with the basic theory of inclined cables. It utilizes the large sag characteristic of ultra-long cables and fits the catenary equation through data from multiple discrete measuring points. It has good adaptability to measurement errors and improves the accuracy of cable force identification. It can be seen that the present application can effectively solve the inapplicability of conventional frequency methods for cable force measurement of ultra-long inclined cables and realize rapid identification of cable forces of ultra-long cables.

[0061] Among them, in the above step 102, the two-dimensional coordinates of the mapping points of each measuring point corresponding to the center line position of the cable body of the inclined cable are calculated from the three-dimensional coordinates of each measuring point, which specifically includes the following steps:

[0062] 201: Convert the three-dimensional coordinates of each of the measuring points into the three-dimensional coordinates of a mapping point corresponding to the center line position of the cable body of the inclined cable.

[0063] Remember i is the three-dimensional coordinate of the i-th measuring point, {C1} i are the three-dimensional coordinates of the mapping point corresponding to the i-th measuring point, i = 1, 2, …, n, and n is the total number of measuring points.

[0064] In step 201, the three-dimensional coordinates of the measuring point {C0} i Convert to the three-dimensional coordinates of the mapping point {C1} i .

[0065] 202: Rotate all the mapping points as a whole until all the mapping points are located in a vertical plane, so as to obtain two-dimensional coordinates of each mapping point.

[0066] Remember {C 2D} i is the two-dimensional coordinate of the mapping point corresponding to the i-th measuring point.

[0067] In step 201, the three-dimensional coordinates of the mapping point {C1} i Converted into the two-dimensional coordinates of the mapping point {C 2D} i .

[0068] In the coordinate system, the Z axis is the vertical direction, the X axis and the Y axis are the horizontal directions, and the vertical plane can be the XZ vertical plane or the YZ vertical plane.

[0069] In the above step 202, the overall rotation of each mapping point is performed, which specifically includes the following steps:

[0070] 301: The three-dimensional coordinates of each of the mapping points {C1} iPerform an overall translation so that one of the mapping points is translated to the origin of the coordinate system, and obtain the translated three-dimensional coordinates of each of the mapping points {C2} i , and record the mapping point as the first point.

[0071] In step 301, after translating one of the mapping points to the origin of the coordinate system, the translated three-dimensional coordinates of each of the mapping points are obtained, which are recorded as {C2} i , is the translation 3D coordinate of the mapping point corresponding to the i-th measuring point.

[0072] 302: Translate the three-dimensional coordinates of each of the mapping points {C2} i Rotate the whole system around the Z axis in the coordinate system until another mapping point is located in the XZ vertical plane or the YZ vertical plane, and obtain the rotated three-dimensional coordinates of each mapping point {C3} i , and record this mapping point as the second point.

[0073] In step 302, after translating another mapping point to be located in the XZ vertical plane or the YZ vertical plane, the rotated three-dimensional coordinates of each mapping point are obtained, which are recorded as {C3} i , is the rotated three-dimensional coordinate of the mapping point corresponding to the i-th measuring point.

[0074] 303: Rotate the rotated three-dimensional coordinates of each of the mapping points around the line connecting the first point and the second point as a whole until the Y coordinate or the X coordinate in the rotated three-dimensional coordinates of all the mapping points is less than a preset value.

[0075] In step 303, the first point and the second point are first connected, and each of the mapping points is rotated around the connecting line as a whole, so that the Y coordinate or the X coordinate in the rotated three-dimensional coordinates of all the mapping points is less than a preset value.

[0076] If the Y coordinates of the rotated three-dimensional coordinates of all mapping points are less than the preset value, it means that all mapping points are in the XZ vertical plane. At this time, the two-dimensional coordinates of each mapping point are obtained. 2D} i .

[0077] If the X coordinates of the rotated three-dimensional coordinates of all mapping points are less than the preset value, it means that all mapping points are in the YZ vertical plane. At this time, the two-dimensional coordinates of each mapping point are obtained. 2D} i .

[0078] The above preset value can be set according to actual needs. The preset value is set as small as possible so that the Y coordinates or X coordinates of all mapping points are as close to 0 as possible, so that all mapping points can be located in the same vertical plane as much as possible.

[0079] The mapping points may be sorted along the length direction of the cable body of the inclined cable, and the first point 5 and the second point 6 may be determined according to actual needs.

[0080] For example, see Figure 2 As shown, in the order from the beam end anchor point 1 to the tower end anchor point 2, the first point 5 can be selected as the first of all mapping points, and the second point 6 can be selected as the last of all mapping points.

[0081] When the vertical plane is the XZ vertical plane in the coordinate system, in the above step 102, a nonlinear optimization solution algorithm is used to perform catenary fitting on the two-dimensional coordinates of each of the mapping points to obtain the linear parameters of the catenary, which specifically includes:

[0082] 401: Constructing the catenary equation:

[0083] 402: Set optimization target T:

[0084] 403: Using a nonlinear optimization solution algorithm, calculate the linear parameter α, as well as x0 and z0 when the optimization target T takes the minimum value;

[0085] Where x0 and z0 are the catenary equations translated to the standard catenary equation The distance that the X-axis and Z-axis move when they coincide. The linear parameter α is the distance from the vertex of the curve to the X-axis of the horizontal coordinate in the standard equation of the catenary; i and z i is the two-dimensional coordinate of the mapping point corresponding to the i-th measuring point, and n is the total number of measuring points.

[0086] Understandably, see Figure 2 As shown, the cable body of the inclined cable is in the form of a catenary, which is only a section of the standard catenary equation. Moreover, since the standard catenary equation is symmetrical about the ordinate axis, while the cable body of the inclined cable is not, it is necessary to translate the cable body to make it coincide with the standard catenary equation. Therefore, when constructing the catenary equation in step 401 of the present application, (x0, z0) is introduced. By converting the standard catenary equation By translating, we can obtain the catenary equation corresponding to the cable body.

[0087] The coordinates of each mapping point are marked as (x i , z i ), and substitute its horizontal coordinate into the catenary equation to calculate the vertical coordinate z(x i ), z i belongs to the measured value, while z(x i) is a calculated value, and after calculation in step 402, the linear parameter α, as well as x0 and z0 can be obtained by taking the minimum value of the optimization target T as a condition.

[0088] After obtaining the linear parameter α, the horizontal component of the cable H = α × q can be calculated based on the unit length weight q of the cable.

[0089] According to the inclination angle β at any position of the cable, the cable force F at any position of the cable can be obtained:

[0090]

[0091] The inclination angle β can be calculated based on the x of the two-dimensional coordinate in the XZ vertical plane, and can be specifically calculated using the following formula:

[0092]

[0093] When the vertical plane is the YZ vertical plane in the coordinate system, in the above step 102, a nonlinear optimization solution algorithm is used to perform catenary fitting on the two-dimensional coordinates of each of the mapping points to obtain the linear parameters of the catenary, which specifically includes:

[0094] 501: Constructing the catenary equation:

[0095] 502: Set optimization target T:

[0096] 503: Using a nonlinear optimization solution algorithm, calculate the linear parameter α, y0 and z0 when the optimization target T takes the minimum value;

[0097] Where y0 and z0 are the catenary equations translated to the standard catenary equation The distance that the Y-axis and Z-axis move when they coincide. The linear parameter α is the distance from the vertex of the curve to the Y-axis of the horizontal coordinate in the standard equation of the catenary; i and z i is the two-dimensional coordinate of the mapping point corresponding to the i-th measuring point, and n is the total number of measuring points.

[0098] The logic of steps 501-503 is the same as that of steps 401-403, and will not be repeated here.

[0099] It can be understood that, for the YZ vertical plane, the inclination angle β can be calculated according to the y of the two-dimensional coordinate in the YZ vertical plane, and can be specifically calculated using the following formula:

[0100]

[0101] Based on the above identification method, the embodiment of the present application further provides a cable force identification system based on catenary fitting, which includes:

[0102] The first module is used to receive the measured three-dimensional coordinates of each measuring point on the inclined cable;

[0103] The second module is used to convert the three-dimensional coordinates of each measuring point into the two-dimensional coordinates of the mapping point corresponding to the center line position of the cable body of each measuring point in the vertical plane;

[0104] The third module is used to perform catenary fitting on the two-dimensional coordinates of each of the mapping points using a nonlinear optimization solution algorithm to obtain the linear parameters of the catenary;

[0105] The fourth module is used to obtain the cable force at any position of the inclined cable based on the linear parameters, the unit length weight of the inclined cable and the inclination angle of the inclined cable at any position.

[0106] Taking a large-span cable-stayed bridge as an example, this application is explained in detail.

[0107] The longest cable of a long-span cable-stayed bridge is 650.9m long, with a designed horizontal projection length of 595m. Standard parallel steel wires of PES7-499 are used. After the construction of the bridge deck accessories is completed, the cable force needs to be measured. This method is used to identify the cable force as follows:

[0108] (1) During the manufacturing of the cable in the factory, 11 permanent measuring points were set on the cable body, with a spacing of about 40m between the measuring points. The measuring points are reliably attached to the cable body, and the coordinates of the cable centerline can be calculated from the measured coordinates of the measuring points. The arrangement of the measuring points is shown in the attached figure. Figure 2 shown.

[0109] (2) The cable-stayed bridge is constructed normally until the cable force measurement condition. Under this condition, a total station is used to measure the three-dimensional coordinates of the permanent measuring points on the cable at night, and the three-dimensional coordinate measurement values ​​of each measuring point are obtained in turn {C1} i , i=1, 2,…, 11.

[0110] (3) The two-dimensional coordinates of the mapping point at the center line of the cable body are calculated from the three-dimensional coordinate measurement values ​​of each measuring point. 2D} i .

[0111] (4) Using nonlinear optimization algorithm to solve the two-dimensional coordinates {C 2D} i Catenary fitting was performed and the catenary linear parameter α was obtained to be 7166.2m.

[0112] (5) Based on the weight per unit length of the cable measured by the manufacturer, q = 0.1226 kN / m, the horizontal component of the cable force is calculated to be H = α × q = 878.6 kN.

[0113] (6) The tangent inclination angle β at the tower end of the cable is about 26.1°, and the calculated cable force at the tower end is 978.2 kN. The tangent inclination angle β at the beam end is about 21.7°, and the calculated cable force at the beam end is 945.8 kN.

[0114] Compared with the finite element calculation model of the whole bridge, the identified cable force is in good agreement with the model, proving that the above calculation process is correct.

[0115] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0116] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0117] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for identifying the cable force of a cable based on catenary fitting, characterized in that: It includes the following steps: Measure the three-dimensional coordinates of each measuring point on the inclined cable; The three-dimensional coordinates of each measuring point are converted into the two-dimensional coordinates of the mapping point of each measuring point corresponding to the center line position of the cable body of the inclined cable in the vertical plane; Using a nonlinear optimization solution algorithm to perform catenary fitting on the two-dimensional coordinates of each of the mapping points to obtain linear parameters of the catenary; The cable force at any position of the cable is obtained based on the linear parameters, the weight per unit length of the cable and the inclination angle at any position of the cable.

2. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 1, characterized in that: Before measuring the three-dimensional coordinates of each measuring point on the stay cable, the method further includes: A plurality of measuring points are set at certain intervals on the cable body of the inclined cable; The stay cables are installed on the bridge.

3. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 1, characterized in that: The distance between two adjacent measuring points is 10m to 50m.

4. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 1, characterized in that: The number of the measuring points is at least 10.

5. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 1, characterized in that: The two-dimensional coordinates of the mapping points of the measuring points corresponding to the centerline positions of the cable bodies of the inclined cables are calculated from the three-dimensional coordinates of the measuring points, specifically including: Convert the three-dimensional coordinates of each measuring point into the three-dimensional coordinates of a mapping point corresponding to the center line position of the cable body of the inclined cable; The mapping points are rotated as a whole until all the mapping points are located in a vertical plane, so as to obtain the two-dimensional coordinates of the mapping points.

6. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 5, characterized in that: Performing an overall rotation on each of the mapping points specifically includes: The three-dimensional coordinates of each of the mapping points are translated as a whole, so that one of the mapping points is translated to the origin of the coordinate system, to obtain the translated three-dimensional coordinates of each of the mapping points, and the mapping point is recorded as the first point; The translated three-dimensional coordinates of each mapping point are rotated as a whole around the Z axis in the coordinate system until another mapping point is located in the XZ vertical plane or the YZ vertical plane, to obtain the rotated three-dimensional coordinates of each mapping point, and the mapping point is recorded as the second point; The rotated three-dimensional coordinates of each of the mapping points are rotated as a whole around the line connecting the first point and the second point until the Y coordinate or the X coordinate in the rotated three-dimensional coordinates of all the mapping points is less than a preset value.

7. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 6, characterized in that: The mapping points are sorted along the length direction of the cable body of the inclined cable, the first point is the first or the last of all the mapping points, and the second point is the last or the first of all the mapping points.

8. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 1, characterized in that: The vertical plane is the XZ vertical plane in the coordinate system. A nonlinear optimization algorithm is used to perform catenary fitting on the two-dimensional coordinates of each mapping point to obtain the linear parameters of the catenary, which specifically include: Construct the catenary equation: Set the optimization target T: Using nonlinear optimization solution algorithm, calculate the linear parameter α when the optimization target T takes the minimum value; Where x0 and z0 are the catenary equations translated to the standard catenary equation The distance that the X-axis and Z-axis move when they coincide. The linear parameter α is the distance from the vertex of the curve to the abscissa axis in the standard equation of the catenary; i and z i is the two-dimensional coordinate of the mapping point corresponding to the i-th measuring point, and n is the total number of measuring points.

9. The method for identifying the cable force of a stay cable based on catenary fitting according to claim 1, characterized in that: The vertical plane is the YZ vertical plane in the coordinate system. A nonlinear optimization algorithm is used to perform catenary fitting on the two-dimensional coordinates of each mapping point to obtain the linear parameters of the catenary, which specifically include: Construct the catenary equation: Set the optimization target T: Using nonlinear optimization solution algorithm, calculate the linear parameter α when the optimization target T takes the minimum value; Where y0 and z0 are the catenary equations translated to the standard catenary equation The distance that the Y-axis and Z-axis move when they coincide. The linear parameter α is the distance from the vertex of the curve to the horizontal axis in the standard equation of the catenary; i and z i is the two-dimensional coordinate of the mapping point corresponding to the i-th measuring point, and n is the total number of measuring points.

10. A cable force identification system based on catenary fitting, characterized in that: It includes: The first module is used to receive the measured three-dimensional coordinates of each measuring point on the inclined cable; The second module is used to convert the three-dimensional coordinates of each measuring point into the two-dimensional coordinates of the mapping point corresponding to the center line position of the cable body of each measuring point in the vertical plane; The third module is used to perform catenary fitting on the two-dimensional coordinates of each of the mapping points using a nonlinear optimization solution algorithm to obtain the linear parameters of the catenary; The fourth module is used to obtain the cable force at any position of the inclined cable based on the linear parameters, the unit length weight of the inclined cable and the inclination angle of the inclined cable at any position.

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