Lossless stay cable replacement method

Abstract

The invention relates to a lossless stay cable replacement method, which comprises the following steps of: arranging a lower anchoring beam in a beam bottom transverse bridge direction at a position where a stay cable to be replaced and a main beam are anchored, arranging two cantilever trolleys on a bridge floor, tensioning the lower anchoring beam through a lower pull rod, mounting a hoop on a cable tower, and arranging a temporary stay cable along a direction parallel to the stay cable to be replaced, the two ends of the temporary inhaul cable are temporarily anchored with the hoop and the lower anchoring beam correspondingly; the stay cable to be replaced is completely transferred to the temporary stay cable, the stay cable to be replaced is dismantled, a new stay cable is installed in situ and tensioned in a grading mode, the temporary stay cable is synchronously released in a grading mode, the cable force of the temporary stay cable is completely transferred to the new stay cable, and stay cable replacement is completed. Temporary anchoring devices do not need to be welded to the main beam and the cable bent tower, the surfaces of the main beam and the cable bent tower are not damaged, and the construction efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering and relates to a method for replacing a stay cable of a cable-stayed bridge. Background Art

[0002] Figure 1 It is a side view of the structure of a cable-stayed bridge. The main beam 1 and the cable tower 2 are connected by multiple cable stays 3. The load of the main beam is transmitted to the cable tower through the cable stays. Each cable stay bears a certain load. The cables are symmetrically arranged on both sides of the cable tower to balance the forces on the cables on both sides.

[0003] After a cable-stayed bridge has been in operation for a period of time, cracks and scratches on the anti-corrosion sheath of the cable may appear, the anchor head may be exposed and rusted, some steel wires of the cable may break, and the anchor clips may fail. These defects may cause the tensile strength of the cable to decrease and fail to meet the requirements for safe operation. Damaged cables need to be replaced in a timely manner.

[0004] When replacing the cable-stayed cable, the original design stress state of the main structure of the bridge should be maintained as much as possible. In order to avoid the load borne by the cable-stayed cable being transferred to the remaining cables during replacement, resulting in excessive changes in the stress of adjacent cables or even breakage, temporary cables can be set up during cable replacement to temporarily bear the load of the removed cable-stayed cable, and the load can be transferred to the new cable after the replacement is completed.

[0005] At present, when setting temporary cables, temporary cable anchoring devices are usually welded on the bridge and the cable tower. After the cable replacement is completed, the temporary cables and temporary anchoring devices are removed together. This not only damages the main beam and the surface of the cable tower, but also has low construction efficiency when batch cable replacement is required. Summary of the invention

[0006] The object of the present invention is to provide a non-destructive cable replacement method with high construction efficiency without damaging the main beam and the cable tower in order to solve the above problems.

[0007] The technical solution of the present invention is as follows:

[0008] A non-destructive stay cable replacement method, characterized in that it comprises the following steps:

[0009] (1) A lower anchor beam is arranged transversely to the bridge at the bottom of the main beam of the cable-stayed bridge, at the anchor position of the cable to be replaced and the main beam, and a cantilever trolley is arranged on both sides of the bridge deck, facing the lower anchor beam. The cantilever trolley is provided with a cantilever beam, one end of which extends to the outside of the bridge. The cantilevers of the two trolleys are tightened with the two ends of the lower anchor beam through the lower tie rod; an anti-slip rubber pad is arranged on the contact surface between the lower anchor beam and the bottom of the beam, and lower anchor plates are welded at both ends of the lower anchor beam;

[0010] (2) A clamp is installed on the cable tower at the same height as the anchor position of the cable to be replaced, wherein the clamp includes two upper anchor beams, which are respectively arranged on both sides of the main tower along the bridge direction, and an upper pull rod is arranged between the two ends of the two upper anchor beams in the transverse direction of the bridge to tighten and fix the two upper anchor beams on the cable tower; the contact surface between the upper anchor beam and the cable tower is provided with an anti-slip rubber pad, and upper anchor plates are respectively welded at both ends of each upper anchor beam;

[0011] (3) A temporary cable is arranged in a direction parallel to the inclined cable to be replaced, wherein the upper end of the temporary cable is anchored to the upper anchor plate on the upper anchor beam, and the lower end of the temporary cable is anchored to the lower anchor plate on the lower anchor beam;

[0012] (4) The temporary cables are tensioned in stages and the cables to be replaced are released in stages simultaneously. After each stage of tensioning and releasing is completed, the elevation and displacement of the main beam control points are measured and verified until the measured cable force of the cables to be replaced is fully transferred to the temporary cables. Then, the cables to be replaced are completely relaxed and removed and cleaned;

[0013] (5) Install new cables in the original position of the removed inclined cables and tension them in stages, and simultaneously tension temporary cables in stages until all the cable forces of the temporary cables are transferred to the new cables; remove the temporary cables and complete the replacement of the inclined cables.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Arrange the lower anchor beam at the bottom of the beam to anchor the lower end of the temporary cable, and install the hoop anchor on the cable tower to anchor the upper end of the temporary cable. There is no need to weld anchor devices on the main beam and cable tower, and the surface of the main beam and cable tower will not be damaged. It is especially beneficial to the protection of the steel beam or composite beam cable-stayed bridge deck and cable tower;

[0016] 2. The lower anchor beam at the bottom of the beam is fixed and moved by a cantilever trolley. The clamp on the main tower can be quickly adjusted according to the anchor height of the cable to be replaced on the main tower, which can significantly improve the construction efficiency when replacing cables in batches;

[0017] 3. The cantilever trolley is located on the bridge deck inspection road, occupies a small space and does not affect traffic during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a side view structural diagram of a cable-stayed bridge;

[0019] Figure 2 It is a schematic diagram of the construction method of replacing the inclined cable of the present invention;

[0020] Figure 3 Schematic diagram of the installation structure of the lower anchor beam and the cantilever trolley on the bridge;

[0021] Figure 4 It is a schematic diagram of the structure of the hoop installed on the cable tower;

[0022] Figure 5 It is a structural schematic diagram of the cantilever trolley. DETAILED DESCRIPTION

[0023] like Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the specific implementation of the present invention is as follows:

[0024] (1) A lower anchor beam 4 is arranged transversely to the bridge at the bottom of the main beam 1 of the cable-stayed bridge, at the anchor position of the cable 3 to be replaced and the main beam, and the two ends of the lower anchor beam 4 are respectively extended to the outside of the main beam. A cantilever trolley 5 is respectively arranged on both sides of the bridge deck, facing the lower anchor beam. The cantilever trolley is provided with a cantilever beam 54, and one end of the cantilever beam extends to the outside of the bridge. The cantilever beams 54 of the two trolleys are tightened with the two ends of the lower anchor beam 4 through the lower tie rod 6; an anti-slip rubber pad is arranged on the contact surface between the lower anchor beam and the bottom of the beam, and lower anchor plates 7 are respectively welded to the two ends of the lower anchor beam 4;

[0025] (2) A clamp is installed on the cable tower 2 at the same height as the anchor position of the cable 3 to be replaced, and the clamp includes two upper anchor beams 8, which are respectively arranged on both sides of the main tower along the bridge direction, and an upper tie rod 9 is arranged between the two ends of the two upper anchor beams 8 in the transverse direction of the bridge to tighten and fix the two upper anchor beams on the cable tower; the contact surface between the upper anchor beam and the cable tower is provided with an anti-slip rubber pad, and upper anchor plates 10 are respectively welded at both ends of each upper anchor beam 8;

[0026] (3) A temporary cable 11 is arranged in a direction parallel to the inclined cable 3 to be replaced, wherein the upper end of the temporary cable 11 is anchored to the upper anchor plate 10 on the upper anchor beam, and the lower end of the temporary cable 11 is anchored to the lower anchor plate 7 on the lower anchor beam;

[0027] (4) The temporary cables 11 are tensioned in stages, and the cables to be replaced 3 are released in stages simultaneously. After each stage of tensioning and releasing is completed, the elevation and displacement of the main beam control point are measured and verified until the measured cable force of the cables to be replaced is fully transferred to the temporary cables, and then the cables to be replaced are completely relaxed for removal and cleaning;

[0028] (5) Install new cables in the original position of the removed inclined cables and tension them in stages, and simultaneously tension temporary cables in stages until all the cable forces of the temporary cables are transferred to the new cables; remove the temporary cables and complete the replacement of the inclined cables.

[0029] During the above construction process, after two force conversions, the force conditions of the lower anchor beam and the upper anchor beam during the construction process are as follows:

[0030] The tension of the temporary cable on the lower anchor beam can be decomposed into vertical force and horizontal force. The vertical force is directly borne by the main beam. Since the lower anchor beam is tightened at the bottom of the beam, the horizontal force is mainly resisted by the friction between the anchor beam and the bottom surface of the main beam.

[0031] The upper anchor beam is subjected to the tension of the temporary cables, which can also be decomposed into vertical force and horizontal force. Since the upper anchor beam is pressed tightly against the tower wall, the vertical force is resisted by the friction between the lower anchor beam and the cable tower, and the horizontal force is offset by the temporary cables symmetrically arranged on both sides.

[0032] When the present invention is implemented, in order to prevent insufficient friction between the lower anchor beam and the bottom of the beam, auxiliary tie rods 13 can be connected between the two ends of the lower anchor beam 4 and the adjacent side span piers 12. The horizontal pulling force applied by the temporary cable to the lower anchor beam in the mid-span direction is resisted by the friction between the lower anchor beam and the bottom of the beam, and the auxiliary tie rods 13 also provide a counter-pulling force in the side span direction to ensure the force-bearing capacity of the lower anchor beam.

[0033] like Figure 5 As shown in the figure, the cantilever trolley 5 includes a chassis 51, a running wheel 52 is arranged at the bottom of the chassis 51, a control cabinet 53 is arranged on the top surface of the chassis facing the outside of the bridge, a driving system is arranged in the control cabinet, and it is used to control the movement of the trolley, the cantilever beam 54 is fixedly arranged on the top of the control cabinet, and a counterweight 55 is arranged on the top surface of the chassis facing the inside of the bridge, and it is used to balance the force on both ends of the cantilever trolley. The cantilever trolley is arranged on the maintenance vehicle walking path on both sides of the bridge deck, and does not affect the normal traffic on the bridge deck.

[0034] The cantilever trolley can carry the lower anchor beam and move along the longitudinal direction of the bridge. When the inclined cables need to be replaced in batches, after the replacement of one inclined cable is completed, the lower pull rod between the cantilever beam and the lower anchor beam is loosened, and the lower anchor beam is suspended under the beam. The two cantilever trolleys carry the lower anchor beam along the bridge deck to the next inclined cable replacement position, and the lower pull rod is retightened to fix the lower anchor beam; at the same time, according to the anchor position of the next inclined cable to be replaced and the cable tower, the clamp is reinstalled and fixed to the corresponding height on the cable tower.

Claims

1. A non-destructive stay cable replacement method, characterized in that: The following steps are involved: (1) A lower anchor beam is arranged at the bottom of the main beam of the cable-stayed bridge in the transverse direction of the bridge, at the anchor position of the cable to be replaced and the main beam, and a cantilever trolley is arranged on both sides of the bridge deck, facing the lower anchor beam. The cantilever trolley is provided with a cantilever beam, and one end of the cantilever beam extends to the outside of the bridge. The cantilevers of the two trolleys are tightened with the two ends of the lower anchor beam through the lower tie rod; an anti-slip rubber pad is arranged on the contact surface between the lower anchor beam and the bottom of the beam, and lower anchor plates are welded at both ends of the lower anchor beam; (2) A clamp is installed on the cable tower at the same height as the anchor position of the cable to be replaced, wherein the clamp includes two upper anchor beams, which are respectively arranged on both sides of the main tower along the bridge direction, and an upper pull rod is arranged between the two ends of the two upper anchor beams in the transverse direction of the bridge to tighten and fix the two upper anchor beams on the cable tower; the contact surface between the upper anchor beam and the cable tower is provided with an anti-slip rubber pad, and upper anchor plates are respectively welded at both ends of each upper anchor beam; (3) A temporary cable is arranged in a direction parallel to the inclined cable to be replaced, wherein the upper end of the temporary cable is anchored to the upper anchor plate on the upper anchor beam, and the lower end of the temporary cable is anchored to the lower anchor plate on the lower anchor beam; (4) The temporary cables are tensioned in stages and the cables to be replaced are released in stages simultaneously. After each stage of tensioning and releasing is completed, the elevation and displacement of the main beam control points are measured and verified until the measured cable force of the cables to be replaced is fully transferred to the temporary cables. Then, the cables to be replaced are completely relaxed and removed and cleaned; (5) Install new cables in the original position of the removed inclined cables and tension them in stages, and simultaneously tension temporary cables in stages until all the cable forces of the temporary cables are transferred to the new cables; remove the temporary cables and complete the replacement of the inclined cables.

2. The non-destructive stay cable replacement method according to claim 1, characterized in that: The cantilever trolley includes a chassis, a running wheel is arranged at the bottom of the chassis, a control cabinet is arranged on the top surface of the chassis facing the outside of the bridge, the cantilever beam is fixedly arranged on the top of the control cabinet, and a counterweight is arranged on the top surface of the chassis facing the inside of the bridge to balance the force on both ends of the cantilever trolley.

3. The non-destructive stay cable replacement method according to claim 1, characterized in that: Auxiliary tie rods are respectively connected between the two ends of the lower anchor beam and the adjacent side span piers.

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