A method for replacing steel strand cables in a cable-stayed bridge

Abstract

This invention discloses a method for replacing steel strand cables in a cable-stayed bridge, comprising the following steps: first, construction preparation; then, removal of the old cable-stayed bridge using either a single-strand traction lowering and removal method or a whole-strand traction lowering and removal method; and finally, installation of the new cable-stayed bridge. The single-strand traction lowering and removal method includes: first, lowering the old cable-stayed bridge as a whole to a certain anchorage length; then, extending the old steel strand at the tensioning end; using a single-hole jack to loosen each old steel strand in stages and cycles; and finally, removing the old steel strand using a circulating winch traction system. The whole-strand traction lowering and removal method includes: first, connecting the tower end anchorage to the tension rod via a connecting sleeve; lowering the tension rod using a through-hole jack and tensioning fixture, lowering the old cable-stayed bridge as a whole until it is completely loosened, completing the cable tension unloading; and finally, removing the old steel strand using a circulating winch traction system. This invention solves the problem of uneven tension unloading in the loosening of the steel strands in cable-stayed bridges and is simple and convenient to operate.

Description

Technical Field

[0001] This invention relates to the field of cable-stayed bridge maintenance. More specifically, this invention relates to a method for replacing steel strand cables in cable-stayed bridges. Background Technology

[0002] With the vigorous development of infrastructure construction, the number of long-span cable-stayed bridges is increasing. In recent years, with rapid economic development, increased traffic volume, and heavier vehicle axle loads, a considerable number of steel arch bridges have developed varying degrees of defects. To achieve sustainable development in bridge construction, my country has actively introduced and developed advanced technologies, materials, and equipment for the reinforcement and renovation of old bridges, and rationally selected reinforcement and renovation schemes to ensure that old and dangerous bridges can continue to function for as long as possible, maximizing the effectiveness of limited funds. my country's bridge construction has truly entered a sustainable development path that emphasizes both construction and maintenance.

[0003] As one of the most important load-bearing components of cable-stayed bridges, stay cables are often prone to damage due to harsh working environments, unreasonable stress conditions, and poor operation and management. This can lead to problems such as PE sleeve rupture and corrosion, severe rusting of steel strands, and even sudden cable breakage, resulting in reduced cable load-bearing capacity and seriously threatening the safe use of cable-stayed bridges. To repair damaged stay cables and restore the bridge's load-bearing capacity, cable replacement measures have been implemented for such cable-stayed bridges both domestically and internationally. However, current methods for replacing steel strand stay cables in large-span cable-stayed bridges present challenges due to uneven unloading of the steel strands, leading to high construction safety risks. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0005] To achieve these objectives and other advantages of the present invention, a method for replacing the steel strand cables of a cable-stayed bridge is provided, comprising the following steps: first, construction preparation is carried out; then, the old cable-stayed bridge cable is removed by a single-strand traction and lowering method or an overall traction and lowering method; and finally, a new cable-stayed bridge cable is installed.

[0006] Preferably, the method for pulling and lowering a single steel strand for dismantling specifically includes the following steps:

[0007] SA1. First, use a through-hole jack to lower the old cable-stayed cable of a certain length of anchorage as a whole.

[0008] SA2. At the release end of each old steel strand in the old cable, extend each old steel strand.

[0009] SA3. Using a single-hole jack, loosen each old steel strand in stages, starting from the bottommost old steel strand to the topmost old steel strand. After each old steel strand is loosened, use a circulating winch traction system to remove it. Do not remove the topmost old steel strand after it has been loosened.

[0010] SA4. After temporarily fixing the beam end anchorage, remove the old outer sleeve and the uppermost old steel strand at the same time.

[0011] SA5. Remove the old anchorages at the beam ends and tower ends.

[0012] Preferably, step SA2 specifically includes: cutting off the surrounding wires of the old steel strand at the unwinding end of the old steel strand, retaining the center wire; welding the center wire of the splicing steel strand to the center wire of the old steel strand; and then welding the splicing steel strand to the surrounding wires of the old steel strand together using welding material.

[0013] Preferably, the uppermost old steel strand is the old steel strand in the old cable that is in contact with the inner top of the old outer sleeve under the action of gravity, and the lowermost old steel strand is the old steel strand in the old cable that is furthest away from the uppermost old steel strand under the action of gravity.

[0014] Preferably, the circulating winch traction system includes:

[0015] The circulating winch is positioned on the bridge deck near the bottom of the tower column;

[0016] The tower end guide device is installed on the tower column near the tower end anchor point of the old cable stay;

[0017] The beam end guide device is located on the bridge deck near the beam end anchorage point of the old cable stays.

[0018] The wire rope of the circulating winch passes through the beam end guide device, goes around the tower end guide device, and returns to the circulating winch, forming a circulation loop.

[0019] Preferably, in step SA5, after temporarily fixing the beam end anchorage, the old outer sleeve and the uppermost old steel strand are removed using the outer sleeve lowering and lifting system; the outer sleeve lowering and lifting system includes a bridge deck winch installed on the bridge deck and a tower top gantry installed on the top of the tower column.

[0020] Preferably, the overall traction and lowering dismantling method specifically includes the following steps:

[0021] SB1. Connect the tower end anchor to the tension rod via the connecting sleeve;

[0022] SB2. Lower the tension rod using a through-hole jack and tensioning fixture until the old cable is relaxed, thus completing the unloading of cable force;

[0023] SB3. The old stay cables and old outer sleeves are dismantled as a whole.

[0024] SB4. Remove the old anchorages at the beam ends and tower ends.

[0025] Preferably, the connecting sleeve includes a sleeve body, on which tapered holes are provided for each anchor hole corresponding to the tower end anchor, and a tapered clamp is provided in each tapered hole, the outer wall taper of the tapered clamp being consistent with the inner wall taper of the tapered hole; the top of the sleeve body is provided with a threaded hole for connection with the tension rod.

[0026] Preferably, the installation of the new stay cable specifically includes: first, installing new anchorages at the tower end and beam end; passing the first steel strand through the beam end anchorage and through the new outer sleeve; hoisting the new outer sleeve and the end of the first steel strand to the tower end for anchoring; installing the clamps at both ends of the first steel strand and tensioning it to the design value; and then installing the remaining new steel strands of the new stay cable in sequence.

[0027] The present invention has at least the following beneficial effects:

[0028] 1. This invention provides a method for replacing steel strand cables in cable-stayed bridges, and provides a method for removing steel strands by pulling down and lowering them individually or by pulling down and lowering them as a whole. By pulling down and lowering the steel strands from the tower end and by pulling down and lowering them by hard traction from the tower end, respectively, this invention solves the problem of uneven unloading of steel strands in large-span cable-stayed bridges and high safety risks, and realizes uniform unloading of old cable stays in a graded and cyclical manner.

[0029] 2. This invention provides a method for replacing steel strand cables in cable-stayed bridges. Considering that during the installation and construction of steel strand cable stays, after tensioning and anchoring grouting, the remaining length of the steel strand at the anchoring end is generally difficult to meet the length required for tensioning during the later cable replacement, the tower end is lowered by extending the steel strand or tensioning rod, without being limited by the remaining length of the steel strand at the original cable anchoring end.

[0030] 3. This invention provides a method for replacing the steel strand cables of a cable-stayed bridge. The new steel strands can be pulled and guided to the tower end for installation using a circulating winch system, or the old steel strands can be lowered to the beam end for removal. The operation is simple and convenient, with low manual labor intensity, high efficiency, fast construction progress, safety and reliability, and facilitates standardized construction.

[0031] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the circulating winch traction system described in this invention;

[0033] Figure 2 This is a schematic diagram of the tower end anchorage described in this invention;

[0034] Figure 3 This is a schematic diagram of the connecting sleeve described in this invention; Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0036] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] like Figures 1-3 As shown, this invention provides a method for replacing steel strand stay cables in a cable-stayed bridge, comprising the following steps: first, construction preparation; then, removing the old stay cables using a single-strand traction and lowering method or a whole-strand traction and lowering method; and finally, installing new stay cables. The construction preparation includes the production, testing, and acceptance of the steel strand stay cables, equipment selection and layout, and installation of temporary construction facilities.

[0038] The method for dismantling a single steel strand by pulling and lowering specifically includes the following steps:

[0039] SA1. First, use a through-hole jack to lower the old cable-stayed cable of a certain length of anchorage as a whole.

[0040] SA2. At the release end of each old steel strand in the old cable, extend each old steel strand.

[0041] SA3. Using a single-hole jack, loosen each old steel strand in stages, starting from the bottommost old steel strand to the topmost old steel strand. After each old steel strand is loosened, use a circulating winch traction system to remove it. Do not remove the topmost old steel strand after it has been loosened.

[0042] SA4. After temporarily fixing the beam end anchorage, remove the old outer sleeve and the uppermost old steel strand at the same time.

[0043] SA5. Remove the old anchorages at the beam ends and tower ends.

[0044] In this technical solution, since the remaining length of the steel strands at the anchorage end after tensioning and anchoring grouting during the installation of the stay cables is generally insufficient to meet the tensioning requirements during subsequent cable replacement, the tower end is lowered by extending the old steel strands, which is not limited by the remaining length of the steel strands at the anchorage end of the original cable. Uniform unloading of the old stay cable 1 is achieved by loosening the old steel strands in stages. After removing the old outer casing and the uppermost old steel strands, the old anchorages at the beam end are removed using a truck crane, and the old anchorages at the tower end are removed using a winch. In step SA3, the loosening and removal sequence of the old steel strands in the old stay cables is from the lowest layer to the highest layer, loosening and removing them layer by layer from bottom to top; the removal sequence on both sides of the center of the old stay cable in the same layer of old steel strands is not limited. The specific steps for the graded loosening of the old steel strand are as follows: After the steel strand to be removed is spliced, it is sequentially threaded through the support foot, tool anchor, and the single-hole jack; the single-hole jack is activated, and the anchor nut is loosened. The old steel strand is then lowered using the steel strand traction. The length of the old steel strand lowered determines the lowering traction force. Once the old steel strand has been lowered to a certain length, the specifications of the circulating winch meet the required lowering traction force. For example, initially loosening by 1cm and holding the load for 1-3 minutes, then loosening by 1cm and holding the load for 1-3 minutes, followed by loosening by 2cm, observing the change in cable force during unloading; the cable force being less than the specifications of the circulating traction winch is used as the basis for ending the cable release at the tower end.

[0045] In another embodiment, step SA2 specifically includes: cutting off the surrounding wires of the old steel strand at the unwinding end of the old steel strand, retaining the center wire; welding the center wire of the splicing steel strand to the center wire of the old steel strand; and then welding the splicing steel strand to the surrounding wires of the old steel strand together using welding material.

[0046] In another embodiment, the uppermost old steel strand is the old steel strand in the old stay cable that is in contact with the inner top of the old outer sleeve under the action of gravity, and the lowermost old steel strand is the old steel strand in the old stay cable that is furthest from the uppermost old steel strand under the action of gravity. Under natural conditions, the uppermost steel strand has the largest contact area with the sleeve under the action of gravity. Therefore, when removing the old steel strands, the outer sleeve is supported by the uppermost old steel strand, and the uppermost old steel strand is retained until the last removal along with the old sleeve.

[0047] In another embodiment, the circulating winch traction system includes:

[0048] The circulating winch 5 is located on the bridge deck near the bottom of the tower column 4;

[0049] The tower end guide device 3 is installed on the tower column 4 near the tower end anchor point of the old cable 1;

[0050] The beam end guide device 2 is located on the bridge deck near the beam end anchorage point of the old cable 1;

[0051] The wire rope of the circulating winch 5 passes through the beam end guide device 2, around the tower end guide device 3, and then returns to the circulating winch 5, forming a circulation loop.

[0052] In this technical solution, such as Figure 1 As shown, during the dismantling or installation of the steel strand, the wire rope of the circulating winch 5 first passes through the outer sleeve, around the beam end guide device 2, and then returns to the circulating winch 5 via the tower end guide device 3. The wire rope is connected to the steel strand through a cable guide plate, and the steel strand is pulled and guided to the tower end for installation or lowered from the tower end to the beam end for dismantling by the circulating winch 5. Preferably, the tower end guide device 3 is located above the tower end anchorage point of the old stay cable 1, and the beam end guide device 2 is located on the side of the beam end anchorage point of the old stay cable 1 near the tower column 4. Both the tower end guide device 3 and the beam end guide device 2 can adopt a fixed pulley structure. In this embodiment, Figure 1 When the wire rope moves clockwise, it is the installation circuit for traction of the steel strand; when the wire rope moves counterclockwise, it is the dismantling circuit for lowering the steel strand.

[0053] In another embodiment, in step SA5, after temporarily fixing the beam end anchorage, the old outer sleeve and the uppermost old steel strand are removed using the outer sleeve lowering and lifting system. The outer sleeve lowering and lifting system includes a bridge deck winch installed on the bridge deck and a tower top gantry installed at the top of the tower column. The bridge deck winch also includes a pulley block. First, the bridge deck winch is used to lift the tower top gantry members to the top of the tower for assembly. Then, the steel wire rope of the bridge deck winch is used to connect the old outer sleeve and the uppermost steel strand, and lower them to the bridge deck to remove them.

[0054] In another embodiment, such as Figure 2 As shown, the overall traction and lowering dismantling method specifically includes the following steps:

[0055] SB1, connect the tower end anchor to the tension rod 9 via the connecting sleeve 6;

[0056] SB2. Lower the tension rod 9 using the through-hole jack 8 and tensioning fixture until the old cable 1 is relaxed, thus completing the unloading of cable force.

[0057] SB3. Lower and dismantle the old cable-stayed cable 1 and the old outer sleeve as a whole;

[0058] SB4. Remove the old anchorages at the beam ends and tower ends.

[0059] In this technical solution, the tower end anchor and tension rod 9 are connected by the connecting sleeve 6, and the tension rod 9 is lowered by the through-hole jack 8 and tensioning fixture to achieve the overall lowering of the old cable 1 with hard traction at the tower end. After a certain length is lowered according to the calculation results, the old cable 1 is relaxed, and the cable force is unloaded. When the length of the tension rod 9 does not meet the requirements, the tension rod 9 can be extended.

[0060] In another embodiment, the connecting sleeve 6 includes a sleeve body 61, on which a tapered hole is provided for each anchor hole corresponding to the tower end anchor, and a tapered clamp 62 is provided in each tapered hole, the outer wall tapering of the tapered clamp 62 being consistent with the inner wall tapering of the tapered hole; the top of the sleeve body 61 is provided with a threaded hole for connection with the tension rod 9.

[0061] like Figure 2 and Figure 3 As shown, the tower end anchor specifically includes a steel anchor box 71, an anchor ring 72, and an anchor head 73. One end of the sleeve 61 has a tapered hole corresponding to each anchor hole on the anchor head 73, and the tapered clamp 63 clamps and limits the position of each old steel strand. Then, the other end of the sleeve 61 is connected to the tension rod 6 via a threaded hole. Further, the tensioning fixture is a tensioning support leg, the connecting sleeve 6 is disposed inside the tensioning support leg, and the tension rod 6 passes through the tensioning support leg and connects to the through-hole jack 8.

[0062] In another embodiment, the installation of the new stay cable specifically includes: first, installing new anchorages at the tower end and beam end; passing the first steel strand through the beam end anchorage and through a new outer sleeve; hoisting the new outer sleeve and the end of the first steel strand to the tower end for anchoring; installing the clamps at both ends of the first steel strand and tensioning it to the design value; and then installing the remaining new steel strands of the new stay cable in sequence. During the above process, the new outer sleeve and the end of the first steel strand are hoisted to the tower end for anchoring using the outer sleeve lowering and lifting system; after the first steel strand is installed and tensioned to the design value using a single-hole jack, the remaining new steel strands are sequentially traction and installed using the circulating winch traction system, and after tensioning, the next new steel strand is installed.

[0063] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for replacing steel strand cables in a cable-stayed bridge, characterized in that, Includes the following steps: First, construction preparations are carried out, then the dismantling is carried out by pulling down a single steel strand, and finally the new cable stays are installed. The method for dismantling a single steel strand by pulling and lowering specifically includes the following steps: SA1. First, use a through-hole jack to lower the old cable-stayed cable of a certain length of anchorage as a whole. SA2. At the release end of each old steel strand in the old cable, extend each old steel strand. SA3. Using a single-hole jack, loosen each old steel strand in stages, starting from the bottommost old steel strand to the topmost old steel strand. After each old steel strand is loosened, use a circulating winch traction system to remove it. Do not remove the topmost old steel strand after it has been loosened. SA4. After temporarily fixing the beam end anchorage, remove the old outer sleeve and the uppermost old steel strand at the same time. SA5. Remove the old anchorages at the beam ends and tower ends; Step SA2 specifically includes: at the unwinding end of the old steel strand, cutting off the surrounding steel wires of the old steel strand and retaining the center steel wire; welding the center steel wire of the splicing steel strand to the center steel wire of the old steel strand; and then welding the splicing steel strand to the surrounding steel wires of the old steel strand together with welding material. The uppermost old steel strand is the old steel strand in the old cable that is in contact with the inner top of the old outer sleeve under the action of gravity, and the lowermost old steel strand is the old steel strand in the old cable that is furthest away from the uppermost old steel strand under the action of gravity.

2. The method for replacing the steel strand cables of a cable-stayed bridge as described in claim 1, characterized in that, The circulating winch traction system includes: The circulating winch is positioned on the bridge deck near the bottom of the tower column; The tower end guide device is installed on the tower column near the tower end anchor point of the old cable stay; The beam end guide device is located on the bridge deck near the beam end anchorage point of the old cable stays. The wire rope of the circulating winch passes through the beam end guide device, goes around the tower end guide device, and returns to the circulating winch, forming a circulation loop.

3. The method for replacing the steel strand cables of a cable-stayed bridge as described in claim 1, characterized in that, In step SA5, after temporarily fixing the beam end anchorage, the old outer sleeve and the uppermost old steel strand are removed using the outer sleeve lowering and lifting system; the outer sleeve lowering and lifting system includes a bridge deck winch installed on the bridge deck and a tower top gantry installed on the top of the tower column.

4. The method for replacing the steel strand cables of a cable-stayed bridge as described in claim 1, characterized in that, The installation of the new stay cables specifically includes: first, installing new anchorages at the tower end and beam end; passing the first steel strand through the beam end anchorage and through the new outer sleeve; hoisting the new outer sleeve and the end of the first steel strand to the tower end for anchoring; installing the clamps at both ends of the first steel strand and tensioning it to the design value; and then installing the remaining new steel strands of the new stay cables in sequence.

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