Cable system tensioning control method suitable for self-anchored cable suspension cooperation system

Abstract

The application discloses a cable system tensioning control method suitable for a self-anchored cable suspension cooperation system, and is characterized by the following steps: firstly, under the premise of ensuring the safety of the force bearing of the main beam and the cable tower, the cable of the cable-stayed area, the cable of the overlapping area and the cable of the side span area are tensioned, wherein the cable of the cable-stayed area and the cable of the side span area are tensioned once, and the cable of the overlapping area is over-tensioned; after tensioning, the main beam in the side span area, the cable-stayed area and the overlapping area needs to be ensured to be disengaged; then, the side span main cable is arranged between the anchoring end of the main beam and the top end of the cable tower, the middle span main cable is arranged between the top ends of the cable towers on the two sides, the shape of the empty cable is adjusted, the suspension area suspender and the overlapping area suspender are hung, and the side span main cable and the suspension area suspender are alternately tensioned while keeping the position pre-offset of the cable saddle unchanged.

Description

Technical Field

[0001] This invention relates to the field of bridge structure design technology, and in particular to a cable system tension control method applicable to self-anchored cable-stayed suspension systems, which is mainly applicable to the construction of cable-stayed suspension bridges. Background Technology

[0002] The long-span self-anchored cable-stayed suspension bridge is a novel bridge system. This system eliminates the need for massive anchorages, making it highly adaptable to various terrains and geological conditions. The cable-stayed section can be constructed as a concrete beam, while the suspension section can be made as a steel beam. In terms of static performance, because cable-stayed bridges have greater stiffness than suspension bridges, the live load deflection and temperature deflection at mid-span are smaller, effectively improving the vertical stiffness of suspension bridges. Therefore, this bridge system is being gradually promoted in my country's bridge construction industry.

[0003] However, in the aforementioned bridge system, the stiffness of the main beam varies greatly between the cable-stayed and suspended zones. Factors such as the continuity of internal forces and deformations in these areas, as well as the fatigue failure of the end hangers, need to be considered.

[0004] Since the degree of error control between the completed main cable alignment and the designed alignment determines the safety of the bridge during its operational period, minimizing this error is the primary objective of construction control. Self-anchored cable-stayed bridges often have suspenders installed within a small area of ​​the mid-span, while other locations in the mid-span and side spans lack suspenders. This results in a significant difference between the completed main cable alignment and the unsupported cable alignment. Consequently, longer extension rods are required as temporary anchors during suspender tensioning.

[0005] In traditional suspension bridge construction, the suspenders often require multiple rounds of tensioning. Through these repeated tensioning processes, the main girder gradually detaches from the supports until the bridge reaches its final state. This method is labor-intensive, involves a wide variety and number of extension rods, is cumbersome, and has a long construction period.

[0006] Traditional cable-stayed bridge construction often involves two stages of cable tensioning, followed by a final cable adjustment after the second stage of permanent load construction to achieve the bridge's final state.

[0007] In other words, whether it is a traditional suspension bridge or a cable-stayed bridge, multiple tensioning operations (on the hangers or the stay cables) are required during the construction process, which results in a relatively long construction period.

[0008] Therefore, there is an urgent need for a method or device that can solve the above problems. Summary of the Invention

[0009] The present invention aims to solve the above-mentioned technical problems by proposing a cable system tensioning control method applicable to a self-anchored cable-stayed suspension cooperative system. This method can greatly reduce the number of cable tensioning operations, shorten the length of the suspender extension rod, reduce the number of suspender tensioning operations, and effectively solve the problem of insufficient operating space in the main tower.

[0010] The technical solution of this invention is: a tension control method for cable systems suitable for self-anchored cable-stayed suspension systems, characterized in that: the tension control method is performed sequentially according to the following steps: Under the premise of ensuring the structural safety of main girder 1 and cable tower 2, the stay cables in the cable-stayed zone are symmetrically tensioned. After tensioning, it is necessary to ensure that main girder 1 within the side span zone 6, cable-stayed zone 7, and overlapping zone 8 is dislodged. A side-span main cable 9 is erected between the anchorage end of the main beam 1 and the top of the tower 2. A middle-span main cable 10 is erected between the tops of the two towers 2. The cable alignment is adjusted, and suspension zone suspenders 11 and overlapping zone suspenders 12 are suspended. While keeping the pre-offset of the cable saddle position constant, the side-span main cable 9 and the suspension zone suspenders 11 are tensioned. Tensioning part of the suspension zone suspenders 11 is used to balance the unbalanced horizontal components of the side-span main cable 9 and the middle-span main cable 10 on both sides of the cable saddle, ensuring the structural safety of the tower 2. The suspension zone suspenders 11 and overlapping zone suspenders 12 are tensioned symmetrically from the mid-span to both sides, and the tensioning process is coordinated with the jacking of the cable saddle. Fine-tune the cable tension of the side span cable 5 and the suspension rod 11 until the stress-free length of the side span cable 5 and the suspension rod 11 is adjusted to the ideal stress-free length.

[0011] In step A, the symmetrical tensioning of the stay cables in the cable-stayed area includes tensioning the stay cables 3 in the cable-stayed area, the stay cables 4 in the overlapping area, and the stay cables 5 in the side span area. The stay cables 3 in the cable-stayed area and the stay cables 5 in the side span area are tensioned once, while the stay cables 4 in the overlapping area are over-tensioned.

[0012] In step B, the tensioning of the main cable 9 in the side span and the suspender 11 in the suspension zone is alternating tensioning.

[0013] Compared with the prior art, the present invention has the following advantages: The cable system tensioning control method disclosed in this invention, applicable to self-anchored cable-stayed suspension systems, significantly reduces the number of cable tensioning operations and shortens the length of the suspender extension rods by rationally and effectively adjusting the construction sequence, thereby effectively solving problems such as insufficient operating space in the main tower. This method adjusts the main beam alignment to a "completed bridge state before secondary dead load" by over-tensioning the cable stays, especially those in the overlapping area. Once the main beam's orientation is adjusted, the suspender installation process becomes more convenient, and the shortened theoretical anchorage distance eliminates the need for excessively long suspender extension rods. Furthermore, the construction process of alternating tensioning of the suspenders in the overlapping area and the main cables in the side spans effectively solves the problem of insufficient space in the main tower and avoids requiring excessively large longitudinal dimensions at the top of the main tower. Moreover, while retaining the pre-deflection of the cable saddle, it ensures moderate tension in the main cables of the side spans before the anchor box opening is poured by alternating tensioning of short suspenders and the main cables in the side spans, preventing shear failure of the concrete around the cable guide. In summary, this tension control method has many advantages and is particularly suitable for application in the field of cable-stayed suspension bridge systems. Currently, the number of cable-stayed suspension bridges that have been built or started construction both domestically and internationally is increasing year by year, indicating a very broad market prospect. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the construction process in step A of this embodiment of the invention.

[0015] Figure 2 This is a schematic diagram of the construction process in step B of this embodiment of the invention.

[0016] Figure 3 This is a schematic diagram of the construction process in step C of this embodiment of the invention.

[0017] Main beam 1, cable tower 2, cable stay in the cable-stayed zone 3, cable stay in the overlapping zone 4, cable stay in the side span zone 5, cable stay in the side span zone 6, cable stay in the cable-stayed zone 7, overlapping zone 8, main cable in the side span 9, main cable in the middle span 10, suspender in the suspension zone 11, suspender in the overlapping zone 12. Detailed Implementation

[0018] Specific embodiments of the present invention will now be described in conjunction with the accompanying drawings. Figures 1 to 3 As shown: A tension control method for a cable system suitable for a self-anchored cable-stayed suspension system is performed in the following steps: First, under the premise of ensuring the structural safety of the main girder 1 and the tower 2, the stay cables in the cable-stayed zone are symmetrically tensioned. This tensioning includes tensioning the stay cables 3 in the cable-stayed zone, the stay cables 4 in the overlapping zone, and the stay cables 5 in the side span zone. The stay cables 3 in the cable-stayed zone and the stay cables 5 in the side span zone are tensioned only once, while the stay cables 4 in the overlapping zone are over-tensioned. After tensioning, it is necessary to ensure that the main girder 1 within the side span zone 6, the cable-stayed zone 7, and the overlapping zone 8 can be dislodged from the scaffolding. Then, the side span main cable 9 is erected between the anchorage end of the main beam 1 and the top of the tower 2, and the middle span main cable 10 is erected between the tops of the two towers 2. The cable alignment is adjusted, and the suspension zone suspenders 11 and the overlapping zone suspenders 12 are suspended. While keeping the pre-offset of the cable saddle position constant, the side span main cable 9 and the suspension zone suspenders 11 are tensioned. The tensioning at this point is alternating. Tensioning the suspension zone suspenders 11 balances the unbalanced horizontal force generated by the side span main cables 9 and the middle span main cables 10 on both sides of the cable saddle, ensuring the stress safety of the tower 2. The suspension zone suspenders 11 and the overlapping zone suspenders 12 are tensioned symmetrically from the mid-span to both sides, and the tensioning is coordinated with the jacking of the cable saddle. Finally, the cable tension of the side span cable 5 and the suspension rod 11 is fine-tuned until the stress-free length of the side span cable 5 and the suspension rod 11 is adjusted to the ideal stress-free length.

[0019] In the cable-stayed suspension system, suspenders are only installed in the mid-span, while no suspenders are installed in the side spans. Therefore, when the cable saddle pre-deflection is set according to the empty cable alignment, if the side span main cable 9 is anchored according to this alignment and only pushed to the design position by the cable saddle, the side span main cable 9 cannot achieve the design alignment. Therefore, the side span main cable 9 needs to be tensioned. Conversely, if the cable saddle is pushed without tensioning the side span main cable 9, the cable pre-deflection in the empty cable alignment will be 3 to 5 times the normal pre-deflection, and the operating space of the main tower will be obviously insufficient.

[0020] By employing the tension control method described in this invention, alternating tensioning of the suspension zone suspenders 11 and the side span main cables 9, the problem of insufficient space in the main tower can be effectively solved, while also eliminating the need for excessively large longitudinal dimensions at the top of the main tower.

Claims

1. A tension control method for a cable system suitable for a self-anchored cable-stayed suspension system, characterized in that: The tension control method is performed sequentially according to the following steps: Under the premise of ensuring the safety of the main beam (1) and the cable tower (2) under stress, the stay cables in the cable-stayed area are symmetrically tensioned. After tensioning, it is necessary to ensure that the main beam (1) in the side span area (6), cable-stayed area (7) and overlapping area (8) is dislodged. A side-span main cable (9) is erected between the anchorage end of the main beam (1) and the top of the tower (2). A middle-span main cable (10) is erected between the tops of the two towers (2). The shape of the empty cable is adjusted, and the suspension zone suspenders (11) and the overlapping zone suspenders (12) are suspended. While keeping the pre-deflection of the cable saddle position unchanged, the side-span main cable (9) and the suspension zone suspenders (11) are tensioned. Part of the suspension zone suspenders (11) are tensioned to balance the unbalanced horizontal component forces generated by the side-span main cables (9) and the middle-span main cables (10) on both sides of the cable saddle, so as to ensure the stress safety of the tower (2). The suspension zone suspenders (11) and the overlapping zone suspenders (12) are tensioned symmetrically from the middle of the span to both sides, and the cable saddle is pushed during the tensioning process. Fine-tune the cable tension of the side span cable (5) and the suspension rod (11) until the stress-free length of the side span cable (5) and the suspension rod (11) is adjusted to the ideal stress-free length.

2. The cable system tension control method applicable to a self-anchored cable-stayed suspension system according to claim 1, characterized in that: Symmetrical tensioning of the cable-stayed cables in the cable-stayed area includes tensioning of the cable-stayed cables (3) in the cable-stayed area, the cable-stayed cables (4) in the overlapping area, and the cable-stayed cables (5) in the side span area. The cable-stayed cables (3) in the cable-stayed area and the cable-stayed cables (5) in the side span area are tensioned once, while the cable-stayed cables (4) in the overlapping area are over-tensioned.

3. The cable system tension control method applicable to self-anchored cable-stayed suspension systems according to claim 1, characterized in that: The tensioning of the main cable (9) on the side span and the suspension rod (11) in the suspension zone is alternating tensioning.

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