A method for determining a tensioning scheme and a control method for tensioning of a buckling tower unbalanced cable force

Abstract

The present application relates to the technical field of construction organization of arch rib cable-stayed buckling system, and particularly relates to a tensioning scheme determination method and a control method for unbalanced cable force tensioning of a buckling tower, wherein the tensioning scheme determination method determines the structural response of key positions under different cable force tensioning and cable force difference conditions in the case of unconditional constraints by using the cable force tensioning values of the arch rib cable-stayed buckling system at each construction stage and combining with a finite element model to obtain a cable force influence matrix or directly importing the cable force influence matrix, determines the allowable cable force tensioning process and the optimal tensioning scheme under given constraint conditions, so that the tensioning scheme can meet the structural response constraint conditions and ensure the safety of the buckling tower at the current construction stage, and the control method calculates and determines the monitoring indexes of each construction stage based on the optimal tensioning scheme, thereby providing reference and guidance for the safe and efficient construction of the arch bridge cable-stayed buckling system, and making the design and construction of the arch rib cable-stayed buckling system scientific and reasonable and safe and feasible.

Description

Technical Field

[0001] This invention relates to the field of construction organization technology for arch rib inclined cable-stayed systems, and in particular to a method for determining and controlling the tensioning scheme for unbalanced cable tensioning of the cable-stayed tower. Background Technology

[0002] The cable-stayed, scaffold-free construction method is widely used in steel pipe arch bridges, steel box arch bridges, steel-concrete composite arch bridges, reinforced concrete arch bridges, and stiffened frame concrete arch bridges. It is an important construction method for segmental assembly of arch bridges, and its advantages are particularly significant in the construction of long-span arch bridges.

[0003] The cable-stayed, scaffold-free construction method requires the application of a cable-stayed system. The cable-stayed tower is a key structure in this system, serving to transfer loads and temporarily fix arch rib segments. During use, in addition to environmental factors (wind load, temperature), the most significant impacts are on the tensioning process of the cables connecting the tower to the arch rib and the back cables connecting the tower to the ground. The cables and back cables are generally tensioned using jacks, but due to limitations in jack stroke and structural safety control, they cannot be tensioned in one go and require staged tensioning to keep the tower in a state of force balance as much as possible. However, the more stages of tensioning, the more construction time and equipment adjustments are required, negatively impacting the construction. Therefore, it is necessary to minimize the number of tensioning stages within the limits of structural safety and to monitor as many parts of the tower as possible during the tensioning process to ensure the tower's safety under the corresponding tensioning scheme.

[0004] Currently, the safety control of tower clamps mainly focuses on the top displacement and the stress at the bottom of the tower. However, for cantilever structures with similar distributed stress, the maximum displacement of the tower clamp may not be at the top. At the same time, due to the effect of bending moment, the maximum stress of the tower clamp may not be at the bottom. Furthermore, since the actual connection of the tower clamp at the bottom is quite complex, there is often stress concentration. Therefore, if the tensioning scheme uses the stress at the bottom of the tower as the only indicator for monitoring, it will produce a large error and affect the safety of the tower clamp under the tensioning scheme.

[0005] Therefore, there is an urgent need for a technical solution to address the technical problem that the tensioning scheme and monitoring indicators of the existing arch rib cable-stayed system are unsuitable during the tensioning process of the unbalanced cable force, which cannot provide the best reference and guidance for the safe and efficient construction of the cable-stayed system and affect the safety of the cable-stayed tower. Summary of the Invention

[0006] The purpose of this invention is to address the technical problem that the tensioning scheme and monitoring indicators of the unbalanced cable tensioning process in the existing arch rib cable-stayed system are unsuitable, failing to provide optimal reference and guidance for the safe and efficient construction of the cable-stayed system and affecting the safety of the cable-stayed tower. This invention provides a method for determining and controlling the unbalanced cable tensioning scheme of the cable-stayed tower.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for determining a tensioning scheme for unbalanced cable tensioning of a cable-stayed tower includes the following steps:

[0009] S1. Obtain the cable force influence matrix of the current construction stage by solving the structural calculation model or software composed of arch rib-tower-cable. The cable force influence matrix includes the structural response influence coefficient and the cumulative structural response of the previous construction stage.

[0010] S2. An unbalanced cable force database is established through the cable force module. The unbalanced cable force database includes several unbalanced cable force combinations, and each combination corresponds to an asymmetric tensioning scheme.

[0011] S3. Based on the cable force influence matrix and the unbalanced cable force database, calculate and obtain the structural response throughout the tensioning process;

[0012] S4. Based on the structural response constraints, select the unbalanced cable force combinations that meet the conditions and determine the feasible region of the unbalanced cable force combinations.

[0013] S5. Determine the optimal tensioning scheme for the current construction stage within the feasible region of unbalanced cable force combinations.

[0014] This invention discloses a method for determining the tensioning scheme of unbalanced cable tensioning for a tower. By analyzing the cable tension values ​​of the arch rib inclined cable-stayed system at each construction stage, and combining this with a finite element model to obtain the cable force influence matrix or directly importing the cable force influence matrix, the structural response of key components under different tension cable forces and cable force differences is calculated and determined under unconditional constraints. Under given constraints, the allowable cable tensioning process and the optimal tensioning scheme are determined, ensuring that the tensioning scheme meets the structural response constraints and guarantees the safety of the tower during the current construction stage.

[0015] As a preferred embodiment of the present invention, it further includes step S6: summarizing the optimal tensioning schemes for each construction stage to determine the unbalanced cable tensioning scheme for the cable-stayed suspension system. This ensures the safety of the suspension tower at each construction stage.

[0016] As a preferred embodiment of the present invention, in S1, the structural calculation model is established based on a finite element database, a structural dimension database, and a construction organization database, and the cable force influence matrix is ​​obtained by applying a unit cable force load to the structural calculation model. Its advantage is that it can obtain the influence matrix of the structural response physical quantities on the cable force at any position and cross-section of the tower.

[0017] As a preferred embodiment of the present invention, in S1, the structural response influence coefficient includes the structural response when the unit force of the fastening cable, the unit force of the backing cable, and the self-weight of the arch rib segment act alone. The physical quantities of the structural response include the final tension value of the fastening cable, the final tension value of the backing cable, and the axial force, bending moment, stress, and displacement of the key parts of the fastening tower.

[0018] As a preferred embodiment of the present invention, in S2, the unbalanced cable force database lists the tension values ​​of the clasp cable and the back cable respectively according to the final tension value of the cable force in an arithmetic sequence, and combines them one by one to obtain the result.

[0019] As a preferred embodiment of the present invention, in S3, the physical quantity of the structural response is Y = C1 × F1 + C2 × F2 + C0, where C1 and C2 are the structural responses when the unit force of the sling and the unit force of the backing cable act alone after considering the load factor; F1 is the initial tension of the sling; F2 is the initial tension of the backing cable; and C0 is the cumulative structural response of the previous construction stage after considering the load factor.

[0020] As a preferred embodiment of the present invention In the formula, A1, A2, and A3 represent the structural responses when the unit force of the ties, the unit force of the backstay, and the self-weight of the arch rib segment act alone, respectively; B1, B2, and B3 represent the vertical displacement responses of the control points when the unit force of the ties, the unit force of the backstay, and the self-weight of the arch rib segment act alone, respectively; G0 represents the cumulative structural response of the previous construction stage; and U represents the vertical displacement of the control point.

[0021] As a preferred embodiment of the present invention, in S4, the structural response constraint conditions include stress conditions and / or crack boundary conditions and / or bearing capacity boundary conditions.

[0022] As a preferred embodiment of the present invention, in S5, the optimal tensioning scheme is determined comprehensively based on the number of turns in the tensioning path and the distance from the tensioning path to the edge of the feasible region, or by placing the initially proposed tensioning scheme into the feasible region for verification.

[0023] A method for controlling the tensioning of unbalanced cables in a tower is provided. The optimal tensioning scheme for each construction stage is obtained by using the tensioning scheme determination method described above. Based on the optimal tensioning scheme, the maximum response value of the tower structure at each construction stage is determined as a monitoring index, and the tensioning of the unbalanced cables in the tower is controlled with reference to the monitoring index.

[0024] The present invention provides a method for controlling the unbalanced cable tension of the cable-stayed tower. Based on the optimal tensioning scheme, the monitoring indicators of each construction stage are calculated and determined. This provides a reference and guidance for the safe and efficient construction of the cable-stayed tower system of arch bridges, making the design and construction of the cable-stayed tower system of arch ribs scientific, reasonable, safe and feasible.

[0025] In summary, due to the adoption of the above technical solutions, the beneficial effects of the method for determining the tensioning scheme of unbalanced cable tensioning of the present invention are:

[0026] By measuring the cable tension values ​​of the arch rib inclined cable-stayed system at each construction stage, and combining the cable tension influence matrix obtained from the finite element model or by directly importing the cable tension influence matrix, the structural response of key parts under different tension cable forces and cable force differences under unconditional constraints is calculated and determined. Under given constraints, the allowable cable tensioning process and the optimal tensioning scheme are determined so that the tensioning scheme can meet the structural response constraints and ensure the safety of the cable-stayed tower at the current construction stage.

[0027] The present invention provides a method for controlling the unbalanced cable tension of the cable-stayed tower. Based on the optimal tensioning scheme, the monitoring indicators of each construction stage are calculated and determined. This provides a reference and guidance for the safe and efficient construction of the cable-stayed tower system of arch bridges, making the design and construction of the cable-stayed tower system of arch ribs scientific, reasonable, safe and feasible. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating a method for controlling the unbalanced cable tensioning of a pylon according to the present invention.

[0029] Figure 2 This is a flowchart illustrating a method for controlling the unbalanced cable tensioning of a pylon, as described in Example 1.

[0030] Figure 3 This is a schematic diagram of the inclined cable-stayed structure of the second arch rib segment of a certain arch bridge in Example 1;

[0031] Figure 4 This is the numerical region of unbalanced cable force combinations that satisfy the stress constraint conditions in Example 1;

[0032] Figure 5 It is the critical axial force-bending moment curve of the section that satisfies the crack boundary conditions in Example 1;

[0033] Figure 6 It is the numerical region of unbalanced cable force combinations that satisfy the cross-sectional crack constraint condition in Example 1;

[0034] Figure 7 It is the critical axial force-bending moment curve of the section that meets the bearing capacity requirements in Example 1;

[0035] Figure 8It is the feasible region of unbalanced cable force combinations that meet the engineering conditions in Example 1;

[0036] Figure 9 This refers to the tower top offset under the proposed cable tensioning scheme in Example 2;

[0037] Figure 10 This refers to the jack readings for the cable tensioning scheme proposed in Example 2;

[0038] Attached image labels: 1-Lock, 2-Back rope. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings.

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] Example 1

[0042] like Figures 1-2 As shown, a method for determining the tensioning scheme of unbalanced cable tensioning for a cable tower includes the following steps:

[0043] S1. Obtain the cable force influence matrix of the current construction stage through the structural calculation model composed of arch rib-tower-cable. The cable force influence matrix includes the structural response influence coefficient and the cumulative structural response of the previous construction stage. The structural calculation model is established based on the finite element database, structural dimension database and construction organization database. The cable force influence matrix is ​​obtained by applying a unit cable force load in the structural calculation model.

[0044] Preferably, when the structural modeling is too complex and the number of key physical quantities of the structure is small, general-purpose software can be used to directly solve the cable force influence matrix.

[0045] Specifically, the finite element database is generated by the finite element module based on the proposed basic structural dimensions of the arch rib, tower, and cables. The finite element database includes node coordinates, element coordinates, element length, node number of the element, and boundary constraints. The structural dimension database is generated by the structural dimension module based on the proposed basic cross-sectional dimensions of the arch rib, tower, and cables. The structural dimension database includes a list of cross-sectional properties of the elements and a stiffness matrix. The construction organization database is generated by the construction organization module based on the proposed construction organization plan information. The construction organization plan information includes the arch rib hoisting sequence, the cables to be tensioned at each hoisting stage, and the final cable force value to be tensioned at this stage.

[0046] S2. An unbalanced cable force database is established through the cable force module. The unbalanced cable force database includes several unbalanced cable force combinations, and each combination corresponds to an asymmetric tensioning scheme.

[0047] It should be noted that since the unbalanced tensioning is applied to a single hoisting segment, and the ties and tail cables of the previous hoisting segments have already been tensioned, the actual tensioning variables are the two factors of the ties and tail cables in this hoisting stage. Therefore, the unbalanced cable force combination is a two-dimensional array, and the corresponding unbalanced tensioning cable force value is also a two-dimensional matrix.

[0048] S3. Based on the cable force influence matrix and the unbalanced cable force database, calculate and obtain the structural response throughout the tensioning process.

[0049] Preferably, the structural response during the entire tensioning process is obtained by calculating the structural response under all asymmetric tensioning schemes obtained by S2. The calculated structural response may include the internal forces, stresses, tower deformation, arch rib control point deviation, and final tensioning value of the cables, etc.

[0050] S4. Based on the structural response constraints, select the unbalanced cable force combinations that meet the conditions and determine the feasible region of the unbalanced cable force combinations.

[0051] Preferably, the structural response of each tensioning scheme obtained from the calculation is verified according to the relevant specifications for material stress, internal force, stability, deformation, etc. The verification process can be carried out by combining cable forces item by item in the structural response database and then checking, or by calculating the critical value expression that meets the specifications and then screening the cable forces. If necessary, a polynomial fitting method can be used to fit the critical value expression to facilitate data verification. Only after screening can the feasible region consisting of unbalanced cable force combinations that meet the engineering conditions be obtained.

[0052] S5. Determine the optimal tensioning scheme for the current construction stage within the feasible region of unbalanced cable force combinations.

[0053] Specifically, one way to determine the optimal tensioning scheme is to minimize the turning points of the tensioning path within the feasible region and maintain a controllable distance between the tensioning path and the edge of the feasible region. The turning points of the tensioning path correspond to the alternating tensioning of the tie cable and the back cable. Another way is to initially propose a tensioning scheme based on the construction site conditions, and then place it within the feasible region to verify whether there are unbalanced cable force combinations that exceed the feasible region's range. If so, corresponding adjustments are made.

[0054] This embodiment presents a method for determining the tensioning scheme of unbalanced cable tensioning for a tower. It utilizes the cable tensioning values ​​of the arch rib inclined cable-stayed system at each construction stage, combined with a finite element model to obtain the cable force influence matrix or directly import the cable force influence matrix. The method calculates and determines the structural response of key components under different tensioning cable forces and cable force differences without constraints. Under given constraints, it determines the permissible cable tensioning process and the optimal tensioning scheme, ensuring that the tensioning scheme at each construction stage meets the structural response constraints and guarantees the safety of the tower at each construction stage.

[0055] like Figure 3 As shown, this embodiment takes the hoisting of the second arch rib segment of a cable-stayed bridge as an example to illustrate the specific process of determining the tensioning scheme for unbalanced cable tensioning of a cable-stayed tower. For the sake of simplification, the cables referred to in this embodiment include cable-stayed cables and back cables. The cable-stayed towers mentioned in this embodiment include any one of the following types: steel truss type, concrete type, and a mixture of steel truss and concrete.

[0056] The basic information proposed in this embodiment for establishing the structural calculation model includes: the calculated span of the arch rib is 90m, the calculated rise is 13.5m, the arch axis is a parabolic equation, the arch rib cross section can be simplified to a 1.5m×2m box section with a wall thickness of 0.2m; the tower is a concrete tower; the bridge tower cross section can be simplified to a 2m×2m rectangular section; the arch rib is hoisted in 6 sections, 3 sections are hoisted on one bank, using a cable system, and the corresponding stage of the tie cable and back cable needs to be tensioned when each hoisted section is in place. Specifically, when hoisting the second arch rib section, the final tension force of the corresponding No. 2 tie cable is 521kN, and the final tension force of the No. 2 back cable is 595kN.

[0057] This embodiment applies a unit load of cable force to the structural calculation model and obtains the structural response influence coefficient through finite element calculation. This coefficient represents the influence of the unit force of the cable tie, the unit force of the back cable, and the self-weight of the arch rib segment on the physical quantities of the structure when they act alone. It also represents the structural response when the unit force of the cable tie, the unit force of the back cable, and the self-weight of the arch rib segment act alone, as well as the cumulative structural response of the previous construction stage, as shown in Table 1.

[0058] Table 1. Influence coefficients of unit cable force, arch rib self-weight, and previous stage load.

[0059] Structural response physical quantities unit 2# cord 2# Back rope Lifting weight Previous stage Axial force at the base of the tower kN -0.053457 -0.305842 -431.901335 -330.054829 Tower base bending moment kNm -0.502167 -2.921226 2276.08297 -275.848695 Tower bottom stress 1 MPa 0.000651736 0.003793021 -3.178744 0.25778 Tower bottom stress 2 MPa -0.000687375 -0.003996915 2.89081 -0.4778165 Tower top offset mm 0.028895 -0.113346 57.45208 -5.037868 Vertical offset of control point mm 0.095351 0.075115 -94.385638 0 Final value of 2-clip kN 0.297032 0.09903 287.624097 0 Backslip 2 final value kN 0.097154 0.54442 241.846818 0

[0060] The overall structural response during the construction of the second segment of the arch rib is as follows:

[0061] Y = A1×F1 + A2×F2 + A3×G + G0 — Equation 1

[0062] In the formula, Y is the physical quantity of the structural response, i.e., the parameter in column 1 of Table 1; A1, A2, and A3 are the structural responses when the unit force of the ties, the unit force of the backing cable, and the self-weight of the arch rib segment act alone, i.e., the data values ​​in columns 3 to 5 of Table 1; G0 is the cumulative structural response of the previous construction stage, i.e., the data value in column 6 of the table above; F1 is the initial tension of the ties, F2 is the initial tension of the backing cable, and G is the segment lifting weight coefficient.

[0063] Due to the action of the cable hoisting system, after the arch rib joint is instantaneously connected, the tension of the cable hoisting system, in conjunction with the ties and back cables, gradually relaxes. Therefore, the actual weight acting on the second segment of the arch rib is not independent, but related to the tension of the ties and back cables. In actual engineering, the coordination point of the cable system, ties, and back cables is to maintain the vertical displacement of the control point at the end of the hoisting segment at 0. Therefore, according to the formula for calculating the vertical displacement of the control point:

[0064] U=B1×F1+B2×F2+B3×G+G0————Equation 2

[0065] In the formula, U represents the vertical displacement of the control point, and B1, B2, and B3 represent the vertical displacement response of the control point when the unit force of the tie cable, the unit force of the back cable, and the self-weight of the arch rib segment act alone, respectively. From Equation 2, the segment lifting weight coefficient for the coordinated cable-stayed system can be obtained as follows:

[0066]

[0067] Combining Equations 3 and 1, the physical quantity Y of the structural response is only related to the cable forces of the ties and backstays at the current stage, and its calculation formula is:

[0068] Y=C1×F1+C2×F2+C0————Equation 4

[0069] In the formula, C1 and C2 are the structural responses when the unit force of the sling and the unit force of the backing cable act alone, after considering the lifting weight coefficient; F1 is the initial tension of the sling; F2 is the initial tension of the backing cable; and C0 is the cumulative structural response of the previous construction stage after considering the lifting weight coefficient.

[0070] Specifically, In the formula, A1, A2, and A3 represent the structural responses when the unit force of the ties, the unit force of the backstay, and the self-weight of the arch rib segment act alone, respectively; B1, B2, and B3 represent the vertical displacement responses of the control points when the unit force of the ties, the unit force of the backstay, and the self-weight of the arch rib segment act alone, respectively; and U represents the vertical displacement of the control point, with a value of 0.

[0071] The above calculation formulas can be used to obtain the structural response when the unit force of the sling, the unit force of the back cable, and the self-weight of the arch rib segment act alone, after considering the lifting weight coefficient, as well as the cumulative value of the physical quantities in the previous construction stage, i.e., the cable force influence matrix in the current construction stage, as shown in Table 2:

[0072] Table 2 Influence coefficients of unit cable force, arch rib self-weight, and previous stage load.

[0073]

[0074]

[0075] Furthermore, an unbalanced cable force database is established through the cable force module. This database is obtained by listing the tension values ​​of the ties and back cables according to an arithmetic progression based on the final cable tension values. In this embodiment, for example... Figure 3 As shown, the final tension of cable #2 is 521kN, and the final tension of cable #2 is 595kN. Taking an arithmetic progression of 10kN, the database of unbalanced cable forces during the hoisting of the second segment of the arch rib is shown in Table 3 below:

[0076] Table 3 Database of unbalanced cable forces during the hoisting of the second segment of the arch rib (kN)

[0077]

[0078] Furthermore, combining Tables 2 and 3, and according to Equation 4, the structural response during the entire cable tensioning process at the current construction stage can be calculated, as shown in Tables 4 to 7:

[0079] Table 4. Axial force at the tower base (kN) under the combined effect of unbalanced cable forces during the hoisting of the second segment of the arch rib.

[0080]

[0081] Table 5. Tower base bending moment (kNm) under the combined effect of unbalanced cable forces during the hoisting of the second segment of the arch rib.

[0082]

[0083]

[0084] Table 6. Stress at the base of the tower under the combined effect of unbalanced cable forces during the hoisting of the second segment of the arch rib (MPa)

[0085]

[0086] Table 7. Stress at the base of the tower under the combined effect of unbalanced cable forces during the hoisting of the second segment of the arch rib (MPa)

[0087]

[0088] Furthermore, based on the structural response constraints, unbalanced cable force combinations that meet the conditions are selected, and the feasible domain of unbalanced cable force combinations is determined. In this embodiment, the constraints of the arch rib cable-stayed system include: the tower bottom stress is not greater than 0.3 MPa, the tower bottom section crack is not greater than 0.1 mm, and the tower bottom section internal force is less than the bearing capacity value as the structural response constraints for illustration.

[0089] Based on the structural response constraints, firstly, by screening the tower bottom stresses from Tables 6 and 7, the following can be obtained: Figure 4 The numerical region of unbalanced cable force combinations satisfying stress constraint conditions is shown; then, based on the cross-sectional dimensions and reinforcement details, and the "Design Code for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts", the following is obtained: Figure 5 The axial force-bending moment critical curve of the section satisfying the crack boundary condition is shown. By performing a polynomial fitting of the axial force on this critical curve, the expression for the bending moment under the cracking condition can be obtained as follows:

[0090] M≤M cr =p0 + p1N + p2N 2 +p3N 3 —Form Five;

[0091] The coefficients P0, P1, P2, and P3 in the bending moment expression take the following values:

[0092] <![CDATA[p3]]> <![CDATA[p2]]> <![CDATA[p1]]> <![CDATA[p0]]> numerical values 8.79E-08 -2.98E-04 -0.09673 308.0855

[0093] According to Equation 5, the internal forces at the tower base section are screened from Tables 4 and 5 to obtain the following results: Figure 6 The numerical region of unbalanced cable force combinations that satisfies the cross-sectional crack constraint condition is shown. Based on the cross-sectional dimensions and reinforcement details, and according to the "Design Code for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts," the following calculations are obtained: Figure 7 The axial force-bending moment critical curve of the section that meets the bearing capacity requirement is shown. By performing a polynomial fitting of the critical curve with respect to the axial force, the bending moment expression for the bearing capacity can be obtained as follows:

[0094] M≤M u =p0 + p1N + p2N 2 +p3N 3 ————Form Six

[0095] The coefficients P0, P1, P2, and P3 in the bending moment expression take the following values:

[0096] <![CDATA[p3]]> <![CDATA[p2]]> <![CDATA[p1]]> <![CDATA[p0]]> numerical values 1.18E-11 -1.45E-05 0.765708 662.4909

[0097] According to Equation 6, the internal forces of the tower base section were screened from Tables 4 and 5. The results show that the proposed unbalanced cable force combinations all meet the section bearing capacity requirements.

[0098] After considering the constraints of stress, cracking, and load-bearing capacity, the following can be obtained: Figure 8 The feasible region for unbalanced cable force combinations that meet the engineering conditions is shown.

[0099] Furthermore, the optimal tensioning scheme for the current construction stage is determined within the feasible region of unbalanced cable force combinations.

[0100] Specifically, based on the arrows in the feasible region, the optimal tensioning scheme for this hoisting stage is as follows: tensioning of the clevis cable to 250kN -- tensioning of the back cable to 510kN -- tensioning of the clevis cable to 480kN -- tensioning of the back cable to the target initial tension of 592kN -- tensioning of the clevis cable 2 to the target initial tension of 521kN. The advantage of this tensioning path is that it requires fewer tensioning operations and allows the structure to maintain a certain safety reserve.

[0101] Other construction stages follow a similar process and will not be described in detail here.

[0102] Example 2

[0103] A method for determining the tensioning scheme of unbalanced cable tensioning of a cable-stayed tower, based on Example 1, further includes S6: summarizing the optimal tensioning schemes for each construction stage to determine the unbalanced cable tensioning scheme for the cable-stayed tower system.

[0104] A method for determining the tensioning scheme of unbalanced cable tensioning of cable-stayed towers is proposed. By summarizing the optimal tensioning schemes at each construction stage, the unbalanced cable tensioning scheme of the cable-stayed tower system can be obtained, which can ensure the safety of the cable-stayed tower at each construction stage.

[0105] Specifically, in this embodiment, the construction stage corresponds to the hoisting stage of each arch rib segment.

[0106] Example 3

[0107] A method for controlling the tensioning of unbalanced cables in a tower is provided. The optimal tensioning scheme for each construction stage is obtained by using the tensioning scheme determination method of Example 1 for unbalanced cable tensioning in a tower. Based on the optimal tensioning scheme, the maximum response value of the tower structure in each construction stage is determined as a monitoring index, and the tensioning of unbalanced cables in the tower is controlled with reference to the monitoring index.

[0108] It should be noted that the cable forces of the ties and back cables corresponding to each hoisting segment are a set of relatively independent unbalanced cable forces, corresponding to an optimal tensioning scheme. Based on the optimal tensioning scheme, the maximum values ​​of structural response physical quantities such as the deviation and stress at important positions of the tower top and tower body can be obtained. After comprehensively considering the structural safety reserve and on-site construction conditions, the monitoring indicators during the actual tensioning of the ties and back cables can be obtained.

[0109] Meanwhile, the cable force value in the unbalanced cable force combination is, in principle, the initial tension cable force value of the cleaving cable and the tail cable. Only after the structural calculation model and post-processing calculation is it the jack control cable force value for this working condition. The cable force difference between the cleaving cable and the tail cable is the value of the unbalanced tensioning by the jack.

[0110] Based on the example of Embodiment 1, this embodiment, by substituting the optimal tensioning scheme of the determined second segment of the arch rib into Equation 4 and combining it with the influence coefficients in Table 1, yields the following result: Figure 9 The diagram shows the tower top offset under the proposed cable tensioning scheme, as well as the final tension values ​​of the tie cables and back cables, as follows: Figure 10 Based on the jack readings of the proposed cable tensioning scheme shown, and considering the overall structural response and on-site construction organization, the construction monitoring scheme for the tensioning cable force of the second segment of the arch rib cable-stayed system can be determined, and then the construction monitoring scheme for other hoisting segments can be determined.

[0111] This embodiment presents a method for controlling the unbalanced cable tension of the cable-stayed arch bridge. Based on the optimal tensioning scheme of the arch rib cable-stayed system, the monitoring indicators for each construction stage are calculated and determined. This provides a reference and guidance for the safe and efficient construction of the cable-stayed arch bridge system, making the design and construction of the arch rib cable-stayed system scientific, reasonable, safe and feasible.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining the tensioning scheme for unbalanced cable tensioning of a cable-stayed tower, characterized in that, Includes the following steps: S1. Obtain the cable force influence matrix for the current construction stage by solving the structural calculation model or software composed of arch rib-tower-cable. The cable force influence matrix includes the structural response influence coefficient and the cumulative structural response of the previous construction stage. The structural calculation model is established based on the finite element database, structural dimension database and construction organization database. The cable force influence matrix is ​​obtained by applying a unit cable force load in the structural calculation model. The structural response influence coefficient includes the structural response when the unit force of the cable, the unit force of the back cable, and the self-weight of the arch rib segment acts alone. The physical quantities of the structural response include the final tension value of the cable, the final tension value of the back cable, and the axial force, bending moment, stress and displacement of the key parts of the tower. S2. An unbalanced cable force database is established through the cable force module. The unbalanced cable force database includes several unbalanced cable force combinations. Each combination corresponds to an asymmetric tensioning scheme. The unbalanced cable force database lists the tensioning values ​​of the clasp cable and the back cable respectively according to the final tensioning value of the cable force in an arithmetic sequence, and combines them one by one to obtain the results. S3. Based on the cable force influence matrix and the unbalanced cable force database, calculate and obtain the structural response throughout the tensioning process. Physical quantities of structural response In the formula, C1 and C2 represent the structural responses when the unit force of the sling and the unit force of the backing cable act alone, considering the lifting weight factor; F1 is the initial tension of the sling; F2 is the initial tension of the backing cable; and C0 is the cumulative structural response of the previous construction stage considering the lifting weight factor. In the formula, A1, A2, and A3 are the structural responses when the unit force of the ties, the unit force of the backstay, and the self-weight of the arch rib segment act alone, respectively; B1, B2, and B3 are the vertical displacement responses of the control points when the unit force of the ties, the unit force of the backstay, and the self-weight of the arch rib segment act alone, respectively; G0 is the cumulative structural response of the previous construction stage; and U is the vertical displacement of the control point. S4. Based on the structural response constraints, select the unbalanced cable force combinations that meet the conditions and determine the feasible region of the unbalanced cable force combinations. S5. Determine the optimal tensioning scheme for the current construction stage within the feasible region of unbalanced cable force combinations.

2. The method for determining the tensioning scheme for unbalanced cable tensioning of a pylon as described in claim 1, characterized in that, It also includes S6, summarizing the optimal tensioning scheme for each construction stage, and determining the unbalanced cable tensioning scheme for the cable-stayed system.

3. The method for determining the tensioning scheme for unbalanced cable tensioning of a pylon as described in claim 1, characterized in that, In S4, structural response constraints include stress conditions and / or crack boundary conditions and / or bearing capacity boundary conditions.

4. The method for determining the tensioning scheme for unbalanced cable tensioning of a pylon as described in claim 1, characterized in that, In S5, the optimal tensioning scheme is determined by comprehensively considering the number of turns in the tensioning path and the distance from the tensioning path to the edge of the feasible region, or by verifying the initial tensioning scheme by placing it in the feasible region.

5. A method for controlling the tensioning of unbalanced cables in a cable tower, characterized in that, The optimal tensioning scheme for each construction stage is obtained using the tensioning scheme determination method for unbalanced cable tensioning of the tower as described in claim 1. Based on the optimal tensioning scheme, the maximum response value of the tower structure at each construction stage is determined as a monitoring index, and the unbalanced cable tensioning of the tower is controlled with reference to the monitoring index.

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