A construction method based on staggered, symmetrical, and graded tensioning of stay cables in a confined space.

Abstract

This invention is a construction method based on staggered, symmetrical, and graded tensioning of cable-stayed bridge towers within a confined space. It involves using a 3D model to check for collisions and conflicts among the jacks during operation; repositioning conflicting jacks at the same height or on the same level by altering their positions to staggered or symmetrical layouts on one side of the same level, or by altering their positions to staggered or diagonally opposite layouts on the same level; analyzing the torsion of the steel anchor beam and the overall stress on the steel anchor beam, steel bracket, and concrete in the relevant segment, and simulating graded tensioning; until a tensioning scheme that meets the tensioning conditions and stress on each component is formed; arranging on-site construction and setting up measuring points; commencing tensioning operations; observing the measuring points during tensioning; and completing the cable tensioning. This method solves the problem of symmetrical tensioning of cable-stayed bridge towers within a confined space, ensuring the safety and reliability of the cable tensioning process and improving the efficiency of cable tensioning.

Description

Technical Field

[0001] This invention relates to the field of cable-stayed bridge construction technology, and more particularly to the tensioning operation of cable stays in bridges, specifically a construction method based on staggered, symmetrical, and graded tensioning of cable stays within a confined space. Background Technology

[0002] A cable-stayed bridge typically consists of towers, cables, and the bridge deck. The cables connect the towers and the bridge deck, and the load on the bridge deck is transferred to the towers by tensioning the cables. One end of each cable is located in the tower, while the other end is anchored to the bridge deck. Tensioning the cable end in the tower achieves the tensioning effect on the entire cable system, thus requiring space within the tower.

[0003] Typically, the internal space of a cable tower is designed from the outset to accommodate the operational space requirements during the later stages of tensioning. However, with the continuous improvement of cable tower designs, smaller towers have gradually emerged. The smaller internal space of these towers can lead to conflicts between the positions of the tensioning jacks during the later stages of cable tensioning, making it impossible to meet the requirements for symmetrical tensioning. For example, tensioning jacks located at the same height (i.e., the same level) around the cable tower may interfere with each other during synchronous operation.

[0004] In the existing technology, there are two possible solutions to the above problems: one is to optimize the jacks by using jacks with lower height to tension the cables; the other is to perform multiple staged tensioning on one side. However, the first method has limited jack sizes that can be optimized, making it only suitable for individual areas with minor spatial conflicts and unable to solve general spatial conflict problems. The second tensioning method, on the other hand, greatly reduces construction efficiency and increases the risks during construction, such as causing uneven stress on the tower, leading to tower twisting or being threatened by unplanned stress, thus jeopardizing the stability of the entire structure. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects and propose a method for performing tensioning operations and ensuring that the cables meet design requirements in a cable tower with limited internal space.

[0006] To achieve the above objectives, the present invention is implemented as follows:

[0007] A construction method based on staggered, symmetrical, and graded tensioning of stay cables in a confined space, including...

[0008] Step 1: Combine the 3D model and analyze the internal space of the tower to simulate the tensioning process of the jacks and check whether there is any collision or conflict between the jacks at the same height or level participating in the same tensioning process.

[0009] Step 2: Based on the results of Step 1, determine the location of the jacks that are colliding.

[0010] Step 3.1: Based on the results of Step 2, change the positions of conflicting jacks at the same height or on the same level:

[0011] Step 3.2: Change the positions of the conflicting jacks to staggered upper and lower levels, and staggered and symmetrical layouts on one side of the same level;

[0012] Step 3.3: Analyze whether the steel anchor beam and the corbel can withstand the horizontal tensile force under the jack position layout in Step 3.2, and the overall stress of the steel anchor beam, steel corbel, and concrete in the segment, to determine whether the tensioning conditions are met.

[0013] Step 4.1 If the tensioning conditions are not met in step 3, add a torsion limiting device to the outside of the steel anchor beam and change the position layout of the jacks to a staggered layout with upper and lower layers and diagonal sides on the same layer, i.e., staggered layout on the same side and diagonal layout on the same layer.

[0014] Step 4.2: Analyze the torsion of the steel anchor beam in Step 4.1 and the overall stress of the steel anchor beam, steel bracket, and concrete in the segment, and further adjust the tensioning scheme;

[0015] Step 5: If steps 4.1 and 4.2 do not meet the tensioning conditions, the position and layout of the jacks shall be changed to staggered, symmetrical, and graded tensioning: Analyze the stress conditions of the steel anchor beam, steel bracket, and concrete in the segment, as well as the operability of the procedure, to determine whether the staggered, symmetrical, and graded tensioning conditions are met; staggered refers to the upper and lower layers of the stay cables being tensioned during construction, symmetrical refers to the tension force of the tower along the bridge direction being basically symmetrical during tensioning, and graded refers to the prestressing tensioning being completed in several stages to reach the design tension, rather than in one stage;

[0016] Step 6: Based on the tensioning construction schemes selected in Steps 3.1 to 5, analyze the overall deformation and stress of the bridge during construction. If the conditions are not met, repeat Steps 3.1 to 5 and make adjustments, including increasing the number of staggered layers and changing the number of jacks in the same layer, until a tensioning scheme that meets the tensioning conditions and the stress of each component is formed.

[0017] Step 7: Based on the construction plan formed in Step 6, arrange on-site construction and set up measuring points;

[0018] Step 8: Begin tensioning operation. During the tensioning process, observe the measuring points. If there is a significant deviation from the theoretical value, suspend construction, return to the previous working condition, find the cause, and resolve it.

[0019] Step 9: Complete cable tensioning.

[0020] in,

[0021] 1. The analysis software used in this project includes Midas and Abaqus. Common similar software includes ANSYS and PKPM.

[0022] 2. The anti-torsion device is not an existing device. During the discussion of the construction method for this project, it was found that diagonal tensioning would cause the steel anchor beam to twist and deform. In order to reduce the torsional deformation, four sets of shear keys were added to the steel bracket as an anti-torsion device.

[0023] 3. The measuring points are arranged about 2m above the base of the lower tower column, and at the locations where the main beam experiences greater stress in theoretical calculations.

[0024] The cable tensioning methods proposed in this invention, including staggered symmetrical tensioning, staggered lateral tensioning, and even staged tensioning, can effectively solve the problem of insufficient space or inability to arrange tensioning jacks due to the confined space inside the cable tower.

[0025] 1. Compared with the traditional single-sided, multi-stage tensioning method, this method balances tensioning effect, construction period, structural safety, and work efficiency. The main component of this method is staggered tensioning, further subdivided into staggered symmetrical and staggered diagonal tensioning. Finally, the decision to perform staged tensioning is made based on overall stability and local stress conditions. This project's construction method discussion involved all the above methods; after comprehensive comparison, staggered, symmetrical, and staged tensioning was adopted. Compared with traditional construction methods, staggered and staged tensioning requires less tensioning space and allows the main beam to gradually detach from the original support system. This effectively controls the bridge alignment and ensures the safety of the pylon structure.

[0026] 2. The cable tensioning work can be completed in a confined space. During the construction process, the modified jack layout allows for stress changes within an acceptable range, thereby ensuring construction stability and balancing the stress and deformation of the tower and bridge.

[0027] 3. It has enriched the construction methods for cable-stayed bridges and provided feasible solutions to the construction challenges of miniaturized cable-stayed bridge towers. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the tensioning construction process proposed in this invention.

[0029] Figure 2 This is a schematic diagram of the staggered symmetrical tensioning operation in this invention.

[0030] Figure 3 This is a schematic diagram of the staggered, diagonal tensioning operation in this invention. Detailed Implementation

[0031] The present invention will be further illustrated below through specific embodiments.

[0032] A construction method based on staggered, symmetrical, and graded tensioning of cable-stayed bridge towers within a confined space is disclosed. The towers have a longitudinal thickness of 5m, and the transverse tower column dimensions vary from 2.8m at the crossbeam to 4.4m at the top. The transverse width at the base of the tower is 4m. The towers above the crossbeam have hollow cross-sections, while those below the crossbeam have solid cross-sections. The upper tower wall thickness is 70cm, and the middle tower wall thickness is 60cm. The internal space of the upper tower column along the bridge direction is 3m wide.

[0033] The hydraulic jacks used for cable traction are YDC240QX, and the hydraulic jacks used for cable tensioning are YCW350. The total length of the steel wire rope on site is approximately 400m; including...

[0034] Step 1: Combine the 3D model and analyze the internal space of the tower to simulate the tensioning process of the jacks and check whether there is any collision or conflict between the jacks at the same height or level participating in the same tensioning process.

[0035] Step 2: Based on the results of Step 1, determine the location of the jacks that are colliding.

[0036] Step 3: Based on the results of Step 2, change the positions of conflicting jacks at the same height or on the same level:

[0037] Step 3.2: Change the positions of the conflicting jacks to staggered upper and lower levels, and staggered and symmetrical layouts on one side of the same level;

[0038] Step 3.3: Analyze whether the steel anchor beam and the corbel can withstand the horizontal tensile force under the jack position layout in Step 3.2, and the overall stress of the steel anchor beam, steel corbel, and concrete in the segment, to determine whether the tensioning conditions are met.

[0039] Step 4: If the tensioning conditions are not met in Step 3, add a torsion limiting device outside the steel anchor beam and change the position layout of the jacks to a staggered layout with upper and lower layers and diagonal sides on the same layer, i.e., staggered layout on the same side and diagonal layout on the same layer.

[0040] Step 4.2: Analyze the torsion of the steel anchor beam in Step 4 and the overall stress of the steel anchor beam, steel bracket, and concrete in the segment, and further adjust the tensioning scheme;

[0041] Step 5: If steps 4 and 4.2 do not meet the tensioning conditions, the jack positions and layouts will be changed to staggered, symmetrical, and graded tensioning: Analyze the stress conditions of the steel anchor beam, steel bracket, and concrete in the segment, as well as the operability of the procedure, to determine whether the staggered, symmetrical, and graded tensioning conditions are met; staggered refers to the stay cables being tensioned vertically during construction; symmetrical refers to the tensioning force along the bridge direction of the tower being basically symmetrical during tensioning; graded refers to the prestressing tensioning being completed in several stages to reach the design tension, rather than all at once.

[0042] Step 6: Based on the tensioning construction schemes selected in Steps 3 to 5, analyze the overall deformation and stress of the bridge during construction. If the conditions are not met, repeat Steps 3 to 5 and make adjustments, including increasing the number of staggered layers and changing the number of jacks in the same layer, until a tensioning scheme that meets the tensioning conditions and the stress of each component is formed.

[0043] Step 7: Based on the construction plan formed in Step 6, arrange on-site construction and set up measuring points;

[0044] Step 8: Begin tensioning operation. During the tensioning process, observe the measuring points. If there is a significant deviation from the theoretical value, suspend construction, return to the previous working condition, find the cause, and resolve it.

[0045] Step 9: Complete cable tensioning.

Claims

1. A construction method based on staggered, symmetrical, and graded tensioning of stay cables within a confined space, characterized by: include Step 1: Combine the 3D model and analyze the internal space of the tower to simulate the tensioning process of the jacks and check whether there is any collision or conflict between the jacks at the same height or level participating in the same tensioning process. Step 2: Based on the results of Step 1, determine the location of the jacks that are colliding. Step 3.1: Based on the results of Step 2, change the positions of conflicting jacks at the same height or on the same level: Step 3.2: Change the positions of the conflicting jacks to staggered upper and lower levels, and staggered and symmetrical layouts on one side of the same level; Step 3.3: Analyze whether the steel anchor beam and the corbel can withstand the horizontal tensile force under the jack position layout in Step 3.2, and the overall stress of the steel anchor beam, steel corbel, and concrete in the segment, to determine whether the tensioning conditions are met. Step 4.1 If the tensioning conditions are not met in step 3, add a torsion limiting device to the outside of the steel anchor beam and change the position layout of the jacks to a staggered layout with upper and lower layers and diagonal sides on the same layer, i.e., staggered layout on the same side and diagonal layout on the same layer. Step 4.2: Analyze the torsion of the steel anchor beam in Step 4.1 and the overall stress of the steel anchor beam, steel bracket, and concrete in the segment, and further adjust the tensioning scheme; Step 5: If steps 4.1 and 4.2 do not meet the tensioning conditions, the position and layout of the jacks shall be changed to staggered, symmetrical, and graded tensioning: Analyze the stress conditions of the steel anchor beam, steel bracket, and concrete in the segment, as well as the operability of the procedure, to determine whether the staggered, symmetrical, and graded tensioning conditions are met; staggered refers to the upper and lower layers of the stay cables being tensioned during construction, symmetrical refers to the tension force of the tower along the bridge direction being basically symmetrical during tensioning, and graded refers to the prestressing tensioning being completed in several stages to reach the design tension, rather than in one stage; Step 6: Based on the tensioning construction schemes selected in Steps 3.1 to 5, analyze the overall deformation and stress of the bridge during construction. If the conditions are not met, repeat Steps 3.1 to 5 and make adjustments, including increasing the number of staggered layers and changing the number of jacks in the same layer, until a tensioning scheme that meets the tensioning conditions and the stress of each component is formed. Step 7: Based on the construction plan formed in Step 6, arrange on-site construction and set up measuring points; Step 8: Begin tensioning operation. During the tensioning process, observe the measuring points. If there is a significant deviation from the theoretical value, suspend construction, return to the previous working condition, find the cause, and resolve it. Step 9: Complete cable tensioning.

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