Analysis method for determining cable length and external connection point position control indexes of fixed-length cable structure

Abstract

The invention relates to an analysis method for determining cable length and external connection point position control indexes of a fixed-length cable structure, and aims at construction error analysis of the fixed-length cable structure, including cable length errors, external connection point position errors and adjacent point position relative errors. And finally, whether the maximum cable force deviation rate and the maximum configuration deviation meet the construction forming allowable form deviation or not is judged to determine that the set error control index can meet the requirement of the construction forming allowable deviation, and more reasonable and comprehensive control indexes are provided for fixed-length cable structure construction.

Description

Technical Field

[0001] The invention belongs to the technical field of the construction of cable structures in civil engineering, and relates to an analysis method for determining the cable length and the control indexes of the external connection point positions of a fixed-length cable structure, in particular to an analysis method for determining the construction control indexes of a fixed-length cable structure by coupling the cable length error, the external connection point position error and the relative error of adjacent points. Background Art

[0002] A cable structure refers to a structure in which cables are used as the main load-bearing members. Among them, the cables can be divided into fixed-length cables and adjustable cables according to whether their anchors are provided with adjusting devices. Correspondingly, the cable structure can be divided into an adjustable cable structure and a fixed-length cable structure according to whether the cables in the cable structure are adjustable. Generally, the construction control indexes of a cable structure mainly include the cable length error, the external connection point position error and the cable tension error, and the control target is that the cable force in the construction forming state meets the allowable deviation value. For an adjustable cable structure, since the adjustment amount of its anchor can eliminate the cable length error and the external connection point position error, the main construction control index is the cable tension error; for a fixed-length cable structure, since its anchor has no adjustment amount, the main construction control indexes are the cable length error and the external connection point position error. The fixed-length cable structure has been popularized and applied due to its advantages such as saving cable materials, beautiful cable ends, and fast on-site construction. However, it has higher requirements for the accuracy of structural design, component production, and on-site construction, and it is necessary to determine clear construction control indexes by using random error analysis according to the specific project situation to ensure that the construction forming state meets the target requirements.

[0003] In the previous construction error analysis of fixed-length cable structures, only the cable length error and the external connection point position error were considered, and both the cable length error and the external connection point position error were set as independent errors, that is, there was no correlation between the length errors of each cable and between the external connection point position errors of each cable. Among the cable groups, generally, the mutual influence of the cable forces is more obvious as the spatial distance is closer. Especially for the relative error of adjacent points in a spoke-type dense cable structure, the influence on the cable force is greater, and it is even the main error control index. In addition, generally, the control target of the construction forming state only has the allowable value of the cable force deviation and does not include the allowable value of the configuration deviation. To sum up, the traditional construction error analysis method of fixed-length cable structures only includes the cable length error and the external connection point position error, does not include the adjacent point error, and is only applicable to general non-dense fixed-length cable structures. The construction error analysis effect for dense cable structures is not satisfactory and can no longer meet the construction error analysis of all fixed-length cable structures.

[0004] Therefore, how to provide more reasonable and comprehensive control indexes for the construction of fixed-length cable structures is an urgent problem to be solved. Summary of the Invention

[0005] The invention provides an analysis method for determining the cable length and the control indexes of the external connection point positions of a fixed-length cable structure.

[0006] In the construction error analysis of fixed-length cable structures, traditional methods only include cable length errors and external connection point errors, and assume that the cable length errors and external connection point errors are independent of each other. The relative errors between adjacent external connection points are not included. In addition, the construction forming state control target only has the allowable value of cable force deviation and does not include the allowable value of configuration deviation. However, in the cable group structure, generally, the mutual influence of cable forces is more obvious as the spatial distance is closer. Especially for the relative errors of adjacent points in the spoke-type dense cable structure, the influence on the cable force is greater, and it is even the main error control index. When considering the relative errors of adjacent points, the errors between each point are closely related and are no longer independent errors. For the construction error analysis of fixed-length cable structures, the present invention includes not only the cable length error and external connection point error, but also the relative error of adjacent points, and the construction forming state control target includes the requirements of cable force and configuration, providing a more reasonable and comprehensive control index for the construction of fixed-length cable structures.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] An analysis method for determining the control indexes of cable length and external connection points of a fixed-length cable structure, comprising the following steps:

[0009] S1. Determine the number k of external connection points between the cable and the surrounding support structure; set the allowable form deviation during construction, that is, the allowable deviation rate δFe of cable force and the allowable deviation ΔUe of configuration; set the number m of defect error condition samples and the normal random distribution guarantee rate φ; set the initial error control indexes: that is, the allowable value Le of cable length error, the allowable value Ce of external connection point error, and the allowable value Re of relative error of adjacent points;

[0010] S2. Sequentially form an external connection node sequence [C1, C2,..., C k and the corresponding cable sequence [L1, L2,..., L k according to the spatial geometric adjacent relationship, and determine the sample standard deviation σ L of cable length error, the sample standard deviation σ C of external connection point error, and the sample standard deviation σ R of relative error of adjacent points according to the normal random distribution guarantee rate φ and the error control indexes;

[0011] S3. Randomly generate a cable length error sample matrix E L according to the cable length error control index Le,

[0012] S4. Randomly generate the error sample vector of the external connection node C1 of m error conditions according to the external connection point error control index Ce

[0013] S5. In the jth error condition, according to the external connection node Ci of and the relative error control index Re of adjacent points to generate the external connection node C i+1 of where 1 ≤ i ≤ k - 1, 1 ≤ j ≤ m;

[0014] S6. Check whether the relative error between the first and last external connection nodes C1 and C k in the j-th error condition meets the adjacent error control index Re, that is If not, recalculate according to S5 until it meets the requirement, and finally obtain the error vector of the j-th error condition

[0015] S7. According to S5 and S6, finally form the external connection point error matrix E of m conditions and k nodes C ,

[0016] S8. Superimpose the cable length error sample matrix E L with the external connection point error sample matrix E C to obtain the total error sample matrix E A ,

[0017] S9. Introduce the errors in the total error sample matrix into the defect-free structure to form m error conditions for analysis, and obtain the maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU max ;

[0018] S10. Judge whether the maximum cable force deviation rate δF max and the maximum configuration deviation ΔU max meet the allowable form deviation during construction; if not, readjust the error control index in S1 and calculate iteratively again.

[0019] Furthermore, in S2, when forming the external connection node sequence [C1, C2,..., C k and the corresponding cable sequence [L1, L2,..., L k according to the spatial geometric adjacent relationship, start from any external connection node and form the sequence in a counterclockwise or clockwise direction along the circumferential direction, and the sequence head and tail form a closed loop in the circumferential direction.

[0020] Furthermore, in S3, when generating the cable length error sample matrix E L , the cable length error samples are independent of each other, and their random error values (i.e., cable length error samples) follow a normal distribution where 1 ≤ i ≤ k, 1 ≤ j ≤ m. When the randomly generated error is greater than +Le, then When When it is less than -Le, then

[0021] Furthermore, in S4, the error sample vector of the first external connection node C1 is generated separately, and its random error value follows a normal distribution When the randomly generated error is greater than +Ce, then = +Ce; when is less than -Ce, then

[0022] Furthermore, in S5, when gradually generating the error vectors of the external connection points in each error condition, except for the first node, the subsequent adjacent point errors are non-independent and are jointly composed of the previous point error and the relative error of the adjacent points. In the j-th error condition, when the previous point error is determined, the relative random error of the adjacent points is generated according to the relative error control index Re of the adjacent points This error value follows a normal distribution When the randomly generated relative error is greater than +Re, then When is less than -Re, then

[0023] The position error value of the (i + 1)-th node in the j-th error condition When the generated error is greater than +Ce, then When is less than -Ce, then

[0024] Furthermore, the maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU max are statistically analyzed based on the normal distribution for the response results of m working conditions, and the maximum value that reaches the normal random distribution guarantee rate φ is obtained. The maximum value here refers to the value with the guarantee rate φ obtained based on the normal distribution on the basis of the structural response of m error conditions being statistically analyzed.

[0025] Furthermore, in S10, when the maximum cable force deviation rate δF max and the maximum configuration deviation ΔU max meet the allowable form deviation during construction forming, it indicates that the error control index set in S1 meets the requirements of the allowable deviation during construction forming.

[0026] Compared with the prior art, for the construction error analysis of the fixed-length cable structure, in addition to including the cable length error and the external connection point position error, the relative error of adjacent points is also included, and the construction forming state control objectives include the requirements of cable force and configuration, providing more reasonable and comprehensive control indexes for the construction of the fixed-length cable structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the analysis flow chart of the method of the present invention;

[0028] Figure 2 is the three-dimensional axonometric view of the roof of the fixed-length cable structure applicable to the present invention;

[0029] Figure 3 is the top view of the cable net of the roof of the fixed-length cable structure applicable to the present invention;

[0030] Figure 4 is the schematic diagram of the spatial relationship of the external connection points of the fixed-length cable structure applicable to the present invention;

[0031] Figure 5 is the schematic diagram of the normal distribution of 500 cable length error samples of the cable L1 of the fixed-length cable structure applicable to the present invention;

[0032] Figure 6 is the schematic diagram of the normal distribution of 500 error samples of the external connection node C1 of the fixed-length cable structure applicable to the present invention;

[0033] Figure 7 is the external connection point error sample matrix E of the fixed-length cable structure applicable to the present invention C The schematic diagram of the normal distribution of 128 external connection point error samples in the first error condition;

[0034] Figure 8 is the external connection point error sample matrix E of the fixed-length cable structure applicable to the present invention C The schematic diagram of the normal distribution of the relative error samples of the head and tail external connection points;

[0035] Figure 9 is the total error sample matrix E of the fixed-length cable structure applicable to the present invention A The schematic diagram of the normal distribution of 128 error samples in the first error condition;

[0036] Explanation of the marks in the figure:

[0037] 1 - Circumferential cable; 2 - Radial cable; 3 - Cable external connection node C1; 4 - Cable external connection node C 128 ; 5 - Cable L1; 6 - Cable L 128 . DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0039] The cable anchor of the "fixed-length cable structure" has no adjustment device. In the previous construction error analysis of the fixed-length cable structure, only the cable length error and the external connection point position error were included, and both were set as independent errors, that is, there is no correlation between the length errors of each cable and between the external connection point position errors of each cable. In the cable group structure, the mutual influence of cable forces is more obvious as the spatial distance is closer. Especially for the relative error of adjacent points in the spoke-type dense cable structure, the influence on the cable force is greater, and it is even the main error control index. In addition, generally, the construction forming state control target only has the allowable value of cable force deviation and does not include the allowable value of configuration deviation.

[0040] In order to provide more reasonable and comprehensive control indexes for the construction of the fixed-length cable structure, the present invention provides an analysis method for determining the cable length and external connection point control indexes of the fixed-length cable structure, as shown in Figure 1 shown, including the following steps:

[0041] S1. Determine the number k of external connection points between the cable and the surrounding support structure; set the allowable form deviation during construction, that is, the allowable cable force deviation rate δFe and the allowable configuration deviation ΔUe; set the number m of defect error condition samples and the normal random distribution guarantee rate φ; set the initial error control indexes: that is, the allowable cable length error value Le, the allowable external connection point position error value Ce, and the allowable relative error value Re of adjacent points.

[0042] S2. Form an external connection node sequence [C1, C2,..., C k and the corresponding cable sequence [L1, L2,..., L k in sequence according to the spatial geometric adjacent relationship. The sequence can be formed in sequence counterclockwise or clockwise from any external connection node, and the head and tail of the sequence form a closed loop in the circumferential direction. Determine the cable length error sample standard deviation σ L , the external connection point position error sample standard deviation σ C , and the adjacent point relative error sample standard deviation σ R according to the normal random distribution guarantee rate φ and the error control indexes.

[0043] S3. Randomly generate a cable length error sample matrix E L , Here, represents the random error value of the i-th cable under the j-th error condition. The random error values of each cable length error sample are independent of each other, and the random error values follow a normal distribution When the randomly generated error is greater than +Le, then When is less than -Le, then

[0044] S4. Randomly generate m error sample vectors of the outreach nodes C1 according to the outreach point error control index Ce Its random error value follows a normal distribution When the randomly generated error is greater than +Ce, then When is less than -Ce, then

[0045] S5. In the j-th error condition, according to the outreach node C i of and the relative error control index Re of the adjacent points, generate the i+1 of the outreach node C where 1 ≤ i ≤ k - 1, 1 ≤ j ≤ m.

[0046] Exemplarily, in the 1st error condition, according to the outreach node C1 error sample vector in and the relative error control index Re of the adjacent points, generate the of the outreach node C2. And so on, according to the outreach node C i of and the relative error control index Re of the adjacent points, generate the i+1 of the outreach node C

[0047] Except for the first node, the subsequent adjacent point errors are non-independent and are jointly composed of the previous point error and the relative error of the adjacent points. In the j-th (1 ≤ j ≤ m) error condition, when the previous point error (1 ≤ i ≤ k - 1) is determined, generate the relative random error of the adjacent points according to the relative error control index Re of the adjacent points This error value follows a normal distribution When the randomly generated relative error is greater than +Re, then When is less than -Re, then The point error value of the (i + 1)-th node in the j-th error condition When the generated error is greater than +Ce, then When is less than -Ce, then

[0048] S6. Since the last node C in each error conditionk is also an adjacent node to the first node C1, so it is necessary to check node C k whether the relative error between the error samples of C and C1 meets the adjacent error control index Re.

[0049] Check whether the relative error between the head and tail external connection nodes C1 and C k in the j-th error condition meets the adjacent error control index Re; if not, recalculate according to S5 until it meets, and finally obtain the error vector of the j-th error condition

[0050] Here, when it does not meet and returns to S5 for recalculation, the relative random error of adjacent points needs to be regenerated according to the relative error control index Re of adjacent points This error value follows a normal distribution Although the relative error control index Re remains unchanged, each time it returns to S5, the newly generated specific values are also different, but only meet a certain probability distribution, so no adjustment is required.

[0051] For example, in the first error condition, check whether the relative error between the head and tail external connection nodes C1 and C k meets the adjacent error control index Re, that is If not, recalculate according to S5 until it meets, and finally obtain the error vector of the first error condition

[0052] S7. According to S5 and S6 of the j-th error condition, finally form the external connection point error matrix E of m conditions and k nodes C , Here, represents the random error value of the i-th external connection point under the j-th error condition.

[0053] S8. Superimpose the cable length error sample matrix E L with the external connection point error sample matrix E C to obtain the total error sample matrix E A ,

[0054] S9. Introduce the errors in the total error sample matrix into the defect-free structure to form m error conditions for analysis, and obtain the maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU max ; the maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU max are the maximum values based on the normal distribution of the response results of m conditions, reaching the guarantee rate φ.

[0055] S10. Determine the maximum cable force deviation rate δF max and the maximum configuration deviation ΔU max to see if they meet the allowable form deviation for construction forming; if not, readjust the error control index in S1 and perform iterative calculations again; if they meet, it means that the error control index set in S1 meets the requirements of the allowable deviation for construction forming.

[0056] The above implementation will be described in more detail below with specific examples.

[0057] Example 1:

[0058] Taking the spoke - type single - layer cable net roof structure of a stadium as an example, the cable net of its roof structure consists of a ring cable 1 and radial cables 2. Among them, the radial cables 2 are fixed - length cables, and their outer ends are connected to the peripheral supporting steel structure. There are 128 radial cables in total, and the distance between the outer connection nodes of each radial cable 2 is only 2 - 4m, belonging to a dense cable system. See Figure 2 and Figure 3 .

[0059] The specific steps for analyzing its construction control index are as follows:

[0060] Step 1: According to the structure configuration, determine that there are k = 128 outer connection points in total for the cables of this cable net structure and the surrounding supporting structure; according to the "Construction Standard for Building Cable Structures" (T / CECS1341 - 2023), set the allowable form deviation for construction forming: the allowable cable force deviation rate δFe = 10%, and the allowable configuration deviation is ΔUe = 2×cantilever span / 1000 = 60mm; determine the number of defect error condition samples m = 500; set the initial error control index: the allowable cable length error value Le = 5mm, the allowable outer connection point position error value Ce = 25mm, and the allowable relative error value of adjacent points Re = 10mm; set the normal random distribution guarantee rate φ = 95%.

[0061] Step 2: Form an outer connection node sequence [C1, C2,..., C 128 in a clockwise direction according to the spatial geometric adjacent relationship. As shown in Figure 4 , it includes the cable outer connection node C1 3 and the cable outer connection node C 128 4, and the corresponding cable sequence is [L1, L2,..., L 128 , including cable L1 5, cable L 128 6, and the sequence forms a closed loop in the circumferential direction. Determine the cable length error sample standard deviation the outer connection point position error sample standard deviation the adjacent point relative error sample standard deviation

[0062] Step 3: According to the allowable value of the cable length error control index Le = 5mm, randomly generate a cable length error sample matrix E L , The cable length error samples are independent of each other, and their random error values follow a normal distribution When the randomly generated error is greater than +5mm, then When is less than -5mm, then Take 500 error samples of the cable L1 for statistics to obtain the error normal distribution diagram, see Figure 5 .

[0063] Step 4: According to the allowable value of the external connection point error control index Ce = 25mm, randomly generate an external connection node C1 error sample vector for m = 500 error conditions Its random error value follows a normal distribution When the randomly generated error is greater than +25mm, then = +25mm; when is less than -25mm, then Take 500 error samples of the external connection node C1 for statistics to obtain the error normal distribution diagram, see Figure 6 .

[0064] Step 5: In the first error condition, according to the external connection node C1 error sample vector in and the relative error control index of adjacent points Re = 10mm, generate the of the external connection node C2. And so on, according to the i of the external connection node C and the relative error control index of adjacent points Re = 10mm, generate the i+1 of the external connection node C

[0065] Except for the first node, the subsequent adjacent point errors are non-independent and are composed of the previous point error and the relative error of adjacent points. In the jth (1 ≤ j ≤ 500) error condition, when the previous point error is determined, according to the relative error control index of adjacent points Re = 10mm, generate the relative random error of adjacent points This error value follows a normal distribution When the randomly generated relative error is greater than +10mm, then When is less than -10mm, then The position error value of the (i + 1)th node in the jth error condition When the generated error is greater than +25 mm, then When is less than -25 mm, then

[0066] Step 6: Since the last node C 128 in each error condition is also an adjacent node to the first node C1, it is necessary to check whether the relative error between the error samples of node C 128 and C1 in each error condition meets the adjacent error control index of 10 mm. In the first error condition, check whether the relative error between the head and tail external connection nodes C1 and C k meets the adjacent error control index of 10 mm, that is If not, recalculate according to Step 5 until it is satisfied, and finally obtain the error vector of the first error condition

[0067] Step 7: According to Steps 5 and 6 of the first error condition, finally form the external connection point position error matrix E C , Take the 128 external connection point position errors of the first error condition in the external connection point position error matrix E C for statistics to obtain the error normal distribution diagram, see Figure 7 , and statistically analyze the relative error distribution between node C 128 and node C1 in 500 error conditions, as shown in Figure 8 . The maximum difference is ±9 mm, which is less than ±10 mm.

[0068] Step 8: Superimpose the cable length error sample matrix E L and the external connection point position error sample matrix E C coupled with the relative error of adjacent points to obtain the total error sample matrix E A , In the total error sample matrix, the normal distribution of the 128 total error samples of the first condition is shown in Figure 9 .

[0069] Step 9: Introduce the errors in the total error sample matrix into the defect-free structure to form 500 error conditions for analysis, and obtain the maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU max . The maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU maxThe maximum value with a 95% assurance rate is statistically obtained based on the normal distribution of the response results of 500 working conditions. Here, when "introducing error samples into a defect-free structure for analysis", the error samples in the total error matrix are equivalent to the errors of each cable length, and the equivalent errors are simulated by applying temperature strains to each stay cable. This is common knowledge in the art and will not be elaborated here.

[0070] Step Ten: Judge the maximum cable force deviation rate δF max and the maximum configuration deviation ΔU max Whether it meets the allowable form deviation during construction forming: that is, δF max ≤10%, ΔU max ≤60mm; Statistically analyze the maximum structural response deviation. Among them, the maximum cable force deviation rate is 8.9%, less than 10%, and the configuration deviation is 56.6mm, less than 60mm. Then the error control index set in Step 1 can meet the requirements of the allowable deviation during construction forming.

[0071] By comparing the construction control indexes obtained by the present invention and the traditional analysis method at the limit of the allowable deviation during construction forming, it can be known that: on the premise that the allowable value of the cable length error is 5mm, the allowable value of the external connection point error obtained by the present invention is 25mm, and the allowable value of the relative error of the adjacent points is 10mm. The traditional method only obtains the allowable value of the external connection point error of 15mm. In comparison, the construction control indexes analyzed by the present invention are more comprehensive and reasonable.

[0072] In the above content, the processing procedures and the like without special instructions are all conventional technologies or well-known technologies in the art and will not be elaborated here.

[0073] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. An analytical method for determining the cable length and external connection point control index of a fixed-length cable structure, characterized in that: The following steps are involved: S1. Determine the number k of external connection points between the cable and the surrounding supporting structure; Set the allowable shape deviation of the construction forming, that is, the allowable deviation rate of cable force δFe and the allowable shape deviation ΔUe; Set the number of defect error condition samples m and the normal random distribution guarantee rate φ; set the error control indicators: the allowable value of cable length error Le, the allowable value of external connection point error Ce, and the allowable value of relative error of adjacent points Re; S2, according to the spatial geometric adjacent relationship, the sequence of external nodes [C1, C2, ..., C k ] and the corresponding cable sequence [L1,L2,...,L k ], according to the normal random distribution guarantee rate φ and the error control index, the sample standard deviation σ of the cable length error is determined L 、External point position error sample standard deviation σ C 、The relative error sample standard deviation of adjacent pointsσ R ; S3. Randomly generate a cable length error sample matrix E according to the cable length error allowable value Le. L , S4, randomly generate the error sample vector of the external node C1 of m error conditions according to the external point error allowable value Ce S5. In the jth error condition, according to the external node C i of and the relative error control index Re of the adjacent points to generate the external node C i+1 of 1≤i≤k-1, 1≤j≤m; S6. Check the j-th error condition, the first and last external connection nodes C1 and C k Whether the relative error of meets the allowable relative error value Re of the adjacent points; if not, recalculate according to S5 until it meets the requirement, and finally obtain the error vector of the jth error condition S7, according to S5 and S6, finally form the external point error matrix E of m working conditions and k nodes C , S8, the cable length error sample matrix E L And the external point error sample matrix E C Superposition is performed to obtain the total error sample matrix E A , S9. Introduce the error in the total error sample matrix into the defect-free structure to form m error conditions for analysis and obtain the maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU max ; S10, determine δF max and ΔU max Whether the allowable morphological deviation of the construction is met; if not, readjust the error control index in S1 and iterate the calculation again.

2. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 1 is characterized in that: In S2, the external node sequence [C1, C2,,,C k ] and the corresponding cable sequence [L1,L2,,,L k ], starting from any external node, a sequence is formed in the ring direction counterclockwise or clockwise, and the beginning and end of the sequence are closed in the ring direction.

3. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 1 is characterized in that: In S3, when generating the cable length error sample matrix E L When , the cable length error samples are independent of each other, and their random error values ​​follow the normal distribution. Among them, 1≤i≤k, 1≤j≤m.

4. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 3 is characterized in that: In S3, when the randomly generated error When it is greater than +Le, when When it is less than -Le, 5. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 1 is characterized in that: In S4, the error sample vector of the first external node C1 Generated separately, its random error value follows a normal distribution When the randomly generated error When it is greater than +Ce, when When it is less than -Ce, 6. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 1 is characterized in that: In S5, when the external point error vectors of each error condition are gradually generated, except for the first node, the subsequent adjacent point errors are not independent and are composed of the previous point error and the adjacent point relative error.

7. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 6 is characterized in that: In the jth error condition, when the previous point error After the determination, the relative random error of the adjacent points is generated according to the relative error control index Re of the adjacent points The error value follows a normal distribution When the relative error of random generation When it is greater than +Re, when When it is less than -Re, 8. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 7 is characterized in that: The position error value of the jth error condition and the i+1th node When the error generated When it is greater than +Ce, when When it is less than -Ce, 9. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 1 is characterized in that: Maximum cable force deviation rate δF max and the maximum cable net configuration deviation ΔU max The response results of m working conditions are statistically analyzed based on the normal distribution to achieve the maximum value of the normal random distribution guarantee rate φ.

10. The analysis method for determining the cable length and external connection point control index of a fixed-length cable structure according to claim 1, characterized in that: In S10, when the maximum cable force deviation rate δF max and the maximum configuration deviation ΔU max If the allowable morphological deviation of construction forming is met, it means that the error control index set by S1 meets the requirements of the allowable deviation of construction forming.

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