Hanging material replacing method and hanging material replacing device

Abstract

To provide a hanging material replacing method and a hanging material replacing device capable of replacing an existing hanging material with a new hanging material without causing vertical displacement of a hanging structure.SOLUTION: By applying the tension between a portion excluding the lower end side of each existing hanger cable 4 and a first temporary hanging material 10 by a second jack 40, the tension of the lower end side of each existing hanger cable 4 is transferred to the second jack 40 and the first temporary hanging material 10, and the connection between the lower end side of each existing hanger cable 4 and a hanging structure 5 side is released, the tension is applied between the first temporary hanging material 10 and a second temporary hanging material 20 by a first jack 30 while reducing the tension between a portion excluding the lower end side of each existing hanger cable 4 and the first temporary hanging material 10 by the second jack 40, so that all tension of each existing hanger cable 4 is transferred to the first and second temporary hanging materials 10, 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a hanging member replacement method and a hanging member replacement device for replacing hanging members of a suspension bridge. [Background technology]

[0002] Generally, suspension bridges that are erected over straits, rivers, etc. are configured to suspend a suspended structure consisting of a deck slab, steel girders, etc., using hanger cables as suspension members connected to a main cable.

[0003] Many of these suspension bridges have been in operation for a long time, and each component may be suffering from deterioration such as corrosion. In particular, the hanger cables are made of steel with a smaller diameter than the main cables, and are subject to repeated loads from vibrations caused by vehicles traveling and wind pressure, which can cause deterioration and reduced durability. These deteriorated hanger cables must be replaced with new ones.

[0004] Conventionally, a method for replacing a hanger cable involves attaching a length-adjustable temporary hanger cable near the existing hanger cable to connect the main cable and the suspended structure, transferring the tension of the existing hanger cable to the temporary hanger cable, and then removing the temporary hanger cable and attaching a new hanger cable (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-143377 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional replacement methods, when transferring the tension of the existing hanger cable to the temporary hanger cable, tension must be applied to the temporary hanger cable using a jack or hoisting device until the existing hanger cable is released from tension. Since the existing hanger cable is stretched by the tension, it shortens by the amount of stretch when the tension is removed. This causes problems, such as vertical displacement of the suspended structure suspended by the temporary hanger cable, which can cause deformation of the suspended structure and significant fluctuations in the tension of other hanger cables.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a hanging member replacement method and hanging member replacement device that can replace existing hanging members with new hanging members without causing any vertical displacement of the suspended structure. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a hanging member replacement method for replacing an existing hanging member, the upper end of which is connected to a main cable side and the lower end of which is connected to a suspended structure side, with a new hanging member, using a first temporary hanging member connected to the suspended structure side, a second temporary hanging member connected to the main cable side, a first tensioning device capable of applying tension between the first temporary hanging member and the second temporary hanging member, and a second tensioning device capable of applying tension between the first temporary hanging member and a portion of the hanging member excluding the lower end side, and the second tensioning device applies tension between the first temporary hanging member and the portion of the existing hanging member excluding the lower end side. By applying tension between the first and second temporary hanging members, the tension on the lower end of the existing hanging member is transferred to the second tensioning device and the first temporary hanging member, the connection between the lower end of the existing hanging member, which is now in an untensioned state, and the hanging structure is released, and while the tension between the part of the existing hanging member excluding the lower end side and the first temporary hanging member is reduced by the second tensioning device, tension is applied between the first and second temporary hanging members, thereby transferring all of the tension of the existing hanging member to the first and second temporary hanging members, and the existing hanging member, which is now in an untensioned state overall, is replaced with a new hanging member.

[0009] In addition, in order to achieve the above-mentioned object, the present invention provides a suspension material replacement device for replacing an existing suspension material, the upper end of which is connected to the main cable side and the lower end of which is connected to the suspended structure side, with a new suspension material, the device comprising: a first temporary suspension member connected to the suspended structure side; a second temporary suspension member connected to the main cable side; a first tensioning device capable of applying tension between the first temporary suspension member and the second temporary suspension member; and a second tensioning device capable of applying tension between the first temporary suspension member and a part of the suspension material excluding the lower end side.

[0010] As a result, when removing the existing hanging material, the second tensioning device applies tension between the part of the existing hanging material excluding the lower end and the first temporary hanging member, thereby transferring the tension on the lower end side of the existing hanging material to the second tensioning device and the first temporary hanging member, and the connection between the lower end side of the existing hanging material, which is now in an untensioned state, and the hanging structure is released.The tension applied between the part of the existing hanging material excluding the lower end and the first temporary hanging member by the second tensioning device is reduced, while the first tensioning device applies tension between the first and second temporary hanging members, thereby transferring all of the tension of each existing hanging material to the first and second temporary hanging members.This makes it possible to transfer tension without changing the total tension between the hanging material and the first temporary hanging member and the tension between the first and second temporary hanging members. [Effects of the Invention]

[0011] According to the present invention, tension can be transferred without changing the total tension between the hanging member and the first temporary hanging member and the tension between the first and second temporary hanging members, so vertical displacement of the suspended structure during tension transfer can be minimized. This significantly reduces deformation of the suspended structure and fluctuations in the tension of other hanging members, which has the advantage of not affecting the durability of the suspended structure or the operation of passing vehicles. [Brief explanation of the drawings]

[0012] [Figure 1] Schematic side view of a suspension bridge showing one embodiment of the present invention. [Figure 2] Overall side view of the hanging material replacement device [Figure 3] Side view of the main part of the hanging material replacement device [Figure 4] Front view of the hanging material replacement device as seen from the arrow AA line [Figure 5] Side view showing the existing hanger cable [Figure 6] Side view showing the hanging material replacement process [Figure 7] Side view showing the hanging material replacement process [Figure 8] Side view showing the hanging material replacement process [Figure 9] Side view showing the hanging material replacement process [Figure 10] Side view showing the hanging material replacement process [Figure 11] Side view showing the hanging material replacement process [Figure 12] Side view showing the hanging material replacement process [Figure 13] Side view showing the hanging material replacement process DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 to 13 show an embodiment of the present invention, which illustrates a method for replacing suspension members of a suspension bridge.

[0014] The suspension bridge 1 shown in the figure is equipped with a main cable 3 stretched across main towers 2, and is configured to suspend a suspended structure 5 consisting of a deck slab, steel girders, etc., by hanger cables 4 as suspension members connected to the main cable 3. In this embodiment, two hanger cables 4 are used at one suspension position.

[0015] As shown in FIG. 5, a socket 4a is provided at each of the upper and lower ends of the hanger cable 4, and a connecting portion 4b is provided at the end of each socket 4a.

[0016] The upper end of the hanger cable 4 is connected to the main cable 3 by a connecting pin 4c that passes through a connecting hole 6a of a hanging fitting 6 attached to the main cable 3 and a connecting portion 4b of the socket 4a. A flange portion 4d is provided at the upper end of the lower socket 4a.

[0017] The lower end of the hanger cable 4 is connected to a connecting member 7 provided on the suspended structure 5 side. The connecting member 7 is made of a plate-shaped member that protrudes upward from the suspended structure 5 side, and has two connecting holes 7a provided at an interval in the bridge axis direction. In this case, the lower end of the hanger cable 4 is connected to the suspended structure 5 side by a connecting pin 4c that passes through the connecting hole 7a of the connecting member 7 and the connecting part 4b of the hanger cable 4.

[0018] As shown in Figures 2 to 4, the hanging material replacement device used in the hanging material replacement method of this embodiment comprises a first temporary hanging member 10 whose lower end is connected to the hanging structure 5 side, a second temporary hanging member 20 whose upper end is connected to the main cable 3 side, a pair of first jacks 30 as first tensioning devices that can apply tension between each of the first temporary hanging members 10 and each of the second temporary hanging members 20, a second jack 40 as a second tensioning device that can apply tension between the first temporary hanging member 10 and the flange portion 4d on the lower end side of each hanger cable 4, and a pair of winding devices 50 that wind up each of the second temporary hanging members 20.

[0019] The first temporary suspension member 10 comprises a pair of first beam sections 11 extending in the bridge axis direction of the suspension bridge 1, a plurality of support sections 12 extending downward from each of the first beam sections 11, and a pair of second beam sections 13 extending perpendicular to the bridge axis across the lower ends of each support section 12.

[0020] The first beam sections 11 are arranged at intervals in the direction perpendicular to the bridge axis, and the support sections 12 are arranged closer to the center than both ends in the longitudinal direction (bridge axis direction).

[0021] Each support column 12 is provided in pairs on each first beam 11 at intervals in the bridge axis direction, and a connecting portion 12a is provided at the lower end of each support column 12 to connect the second beam 13 in a freely rotatable manner.

[0022] Each second beam section 13 has connecting sections 13a with the support section 12 on both ends in the longitudinal direction (perpendicular to the bridge axis), and each connecting section 13a is rotatably connected to connecting section 12a of the support section 12. In addition, a connecting section 13b that is connected to connecting member 7 of the suspended structure 5 is provided in the longitudinal center of each second beam section 13, and the second beam section 13 is connected to the suspended structure 5 by connecting pin 13c that passes through connecting section 13b and second connecting hole 7b of connecting member 7.

[0023] In addition, at both ends of each first beam section 11 in the bridge axis direction, a pair of third beam sections 14 are provided at intervals in the bridge axis direction, extending perpendicular to the bridge axis across the underside of each first beam section 11, and at the center of each first beam section 11 in the bridge axis direction, a pair of fourth beam sections 15 are provided at intervals in the bridge axis direction, extending perpendicular to the bridge axis across the underside of each first beam section 11.

[0024] Each second temporary suspension member 20 is made up of multiple well-known strands of PC steel wire, one end of which is connected to a connecting portion 21 that is connected to the main cable 3. One end of the second temporary suspension member 20 is connected to the main cable 3 by a connecting pin 21a that passes through a connecting hole 22a of a temporary suspension fitting 22 attached to the main cable 3 and the connecting portion 21. The other end of each second temporary suspension member 20 is wound up on a respective winding device.

[0025] Each first jack 30 is a well-known strand jack and is disposed at both longitudinal ends of each first beam portion 11 of the first temporary suspending member 10. A strand jack is a jack device that continuously feeds or retracts a strand by repeatedly gripping and releasing the strand by using a hydraulic device to move one of a pair of upper and lower clamp mechanisms capable of gripping the strand up and down, and is used for lifting and lowering heavy objects. Each first jack 30 is attached to the longitudinal center of each third beam portion 14 of the first temporary suspending member 10, and each has a second temporary suspending member 20 inserted therein.

[0026] The second jack 40 includes a plurality of hydraulic cylinders 41 and support members 42 that support the lower ends of the hydraulic cylinders 41, and the support members 42 are adapted to engage with the flange portions 4d of the hanger cable 4 from above. Each hydraulic cylinder 41 is adapted to press the corresponding fourth beam portion 15 of the first temporary hanging member 10 upward by its corresponding drive rod 41a.

[0027] Each winding device 50 is a well-known strand winding device installed on the suspended structure 5 and is configured to wind or unwind the second temporary suspension member 20 onto or from a rotatable reel 51 .

[0028] Next, a method for replacing a suspension member according to this embodiment will be described with reference to Figures 6 to 13. In these figures, the tension between the main cable 3 and the suspended structure 5 is indicated by a thick line.

[0029] First, a new connecting member 60 is attached to the connecting member 7 of the suspended structure 5. The connecting member 60 has connecting holes 60a for connecting the first temporary hanging member 10, and the connecting members 60 are joined to both sides of the connecting member 7 in the bridge axis direction. Note that the joining of each connecting member 60 is performed by welding, but it may also be done by bolting.

[0030] Next, a suspension member replacement device is installed on the suspended structure 5. That is, as shown in Figures 6 and 7, each connecting portion 13b of the first temporary suspension member 10 is connected to the connecting hole 60a of each connecting member 60 on the suspended structure 5 side with the connecting pin 13c, and the support member 42 of the second jack 40 is engaged from above with the flange portion 4d of each existing hanger cable 4. Next, temporary suspension fittings 22 are attached to two locations in the bridge axis direction of the main cable 3, and each second temporary suspension member 20 unwound from each winding device 50 is reeled out upward by each first jack 30, and one end of each second temporary suspension member 20 is connected to each temporary suspension fitting 22.

[0031] Next, by using each first jack 30 to pull down each second temporary hanging member 20 relative to the first temporary hanging member 10, a small tension is applied between the first temporary hanging member 10 and each second temporary hanging member 20, and the first temporary hanging member 10 and the second temporary hanging member 20 are tensioned.

[0032] After this, tension is applied between the first temporary hanging member 10 and the flange portion 4d of each hanger cable 4 by the second jack 40, thereby transferring the tension on the lower end side of each hanger cable 4 (the portion from the flange portion 4d to the connecting portion 4b) to the second jack 40 and the first temporary hanging member 10, as shown in Figure 8.

[0033] This creates a reaction-free state between the connecting portion 4b at the lower end of each hanger cable 4 and the connecting member 7 of the suspended structure 5, so the connecting pin 4c is removed and the connection between the lower end of each hanger cable 4 and the connecting member 7 is released.

[0034] Next, as shown in Figure 9, by gradually lowering the drive rods 41a of each hydraulic cylinder 41 of the second jack 40, the tension on the first temporary hanging member 10 and each existing hanger cable 4 by the second jack 40 is reduced, while the second temporary hanging member 20 is gradually pulled down by the first jack 30, thereby applying tension between the first temporary hanging member 10 and the second temporary hanging member 20, and all of the tension on each existing hanger cable 4 is transferred to the first and second temporary hanging members 10, 20.

[0035] As a result, the tension is transferred without changing the sum of the tension between each hanger cable 4 and the first temporary hanging member 10 and the tension between the first and second temporary hanging members 10, 20. In this case, each hanger cable 4 that had been stretched due to tension becomes untensioned as a whole and shrinks, becoming shorter by length L than when tensioned, as shown in Figure 9. At this time, because the connection between the lower end of each hanger cable 4 and the connecting member 7 is released, the change in length L of each hanger cable 4 does not cause any vertical displacement on the suspended structure 5 side.

[0036] Next, the connecting pins 4c that connect the upper end connecting portions 4b of each existing hanger cable 4, which is now in a tension-free state, to the hanging fittings 6 are removed, and each existing hanger cable 4 is removed from the hanging fittings 6 as shown in Figure 10.

[0037] 11, the upper ends of the new pair of hanger cables 8 are connected to the main cable 3. At this time, the connecting portions 8b of the sockets 8a of each hanger cable 8 are connected to the hanging fittings 6 by connecting pins 8c.

[0038] Next, as shown in Figure 12, by gradually pushing up the first temporary hanging member 10 using the drive rod 41a of each hydraulic cylinder 41 of the second jack 40, tension is applied between the first temporary hanging member 10 and the flange portion 8d of each hanger cable 8 while the second temporary hanging member 20 is gradually pulled up using the first jack 30, thereby reducing the tension between the first temporary hanging member 10 and the second temporary hanging member 20 and transferring all of the tension between the first temporary hanging member 10 and the second temporary hanging member 20 to the part of each hanger cable 8 excluding the lower end side (the part from the flange portion 8d to the connecting portion 8b), the second jack 40, and the first temporary hanging member 10.

[0039] As a result, each hanger cable 8 is stretched by a length L due to tension from the untensioned state, and the connecting portion 8b at the lower end of each hanger cable 8 and the connecting member 7 of the suspended structure 5 are connected by the connecting pin 8c.

[0040] After this, as shown in Figure 13, the drive rod 41a of each hydraulic cylinder 41 of the second jack 40 is lowered to release the tension on the first temporary hanging member 10 by the second jack 40, and the tension on the first temporary hanging member 10 is transferred to the entire length of each hanger cable 8.

[0041] After replacing each existing hanger cable 4 with a new hanger cable 8 in the above manner, the hanging material replacement device is moved to another hanging position, and the next hanging material replacement work is carried out in the same manner as described above. At this time, the length of the hanger cables 4 of the suspension bridge 1 varies depending on the hanging position, but by winding or unwinding each second temporary hanging member 20 with each winding device 50, the length of each second temporary hanging member 20 is adjusted according to the length of the hanger cable 4.

[0042] As described above, according to this embodiment, when removing each existing hanger cable 4, tension is applied between the portion of each existing hanger cable 4 excluding the lower end side and the first temporary suspension member 10 by the second jack 40, so that the tension on the lower end side of each existing hanger cable 4 is transferred to the second jack 40 and the first temporary suspension member 10, and the connection between the lower end side of each existing hanger cable 4, which is now in a tension-free state, and the suspended structure 5 side is released, and each existing hanger cable 4 is removed by the second jack 40. By applying tension between the first temporary suspension member 10 and the second temporary suspension member 20 with the first jack 30 while reducing the tension between the portion of the cable 4 excluding its lower end and the first temporary suspension member 10, all of the tension in each existing hanger cable 4 is transferred to the first and second temporary suspension members 10, 20, so that the tension can be transferred without changing the total of the tension between each hanger cable 4 and the first temporary suspension member 10 and the tension between the first and second temporary suspension members 10, 20. This makes it possible to extremely reduce vertical displacement of the suspended structure 5 during tension transfer, thereby significantly suppressing deformation of the suspended structure 5 and fluctuations in the tension of other hanger cables, with the advantage of not affecting the durability of the suspended structure 5 or the running of passing vehicles.

[0043] Furthermore, when installing new hanger cables 8, each of the existing hanger cables 4, which have been put into a tension-free state as a whole, is replaced with a new hanger cable 8, and then tension is applied between the first temporary hanging member 10 and the part of each new hanger cable 8 excluding the lower end side by the second jack 40, while the tension between the first temporary hanging member 10 and the second temporary hanging member 20 is reduced by the first jack 30. This releases the tension of the first and second temporary hanging members 10, 20 from the part of each new hanger cable 8 excluding the lower end side by the second jack 40. 0 and the first temporary hanging member 10, and after connecting the lower end of each new hanger cable 8 to the suspended structure 5, the tension between the first temporary hanging member 10 and the part of each new hanger cable 8 excluding the lower end thereof is released by the second jack 40, thereby transferring the tension of the first temporary hanging member 10 to the entire new hanger cable 8.As a result, as described above, the tension can be transferred without changing the total tension between each hanger cable 8 and the first temporary hanging member 10 and the tension between the first and second temporary hanging members 10, 20.

[0044] Furthermore, while the first jack 30 applies a small tension between the first temporary hanging member 10 and the second temporary hanging member 20 to tension the first temporary hanging member 10 and the second temporary hanging member 20, the second jack 40 applies tension between the first temporary hanging member 10 and the second temporary hanging member 20 while reducing the tension between the first temporary hanging member 10 and the portion of each existing hanger cable 4 excluding the lower end side.Therefore, when the tension applied by the second jack 40 begins to be reduced, the descent of the first temporary hanging member 10 can be regulated by the tension between the first temporary hanging member 10 and the second temporary hanging member 20, and vertical displacement during tension transfer can be effectively prevented.

[0045] Furthermore, because a strand is used as the second temporary hanging member 20 and a strand jack is used as the first jack 30, the length of the second temporary hanging member 20 (strand) from the main cable 3 side to the first jack 30 can be changed according to the length of the hanger cable 4. This eliminates the need to prepare temporary hanger cables of different lengths for each hanger cable 4 at each hanging position, thereby reducing the production costs and time required for producing many different types of temporary hanger cables.

[0046] In this case, after replacing each existing hanger cable 4 with a new hanger cable 8, the hanging material replacement device is moved to another hanging position and the length of each second temporary hanging member 20 is adjusted according to the length of the hanger cable 4 at the other hanging position, so that the same hanging material replacement device can be used even at hanging positions where the hanger cable lengths are different, thereby making the hanger cable replacement work extremely efficient.

[0047] In the above embodiment, the second jack 40 is configured by a plurality of hydraulic cylinders 41, but a center hole jack may also be used.

[0048] Furthermore, in the above embodiment, two hanger cables 4, 8 are provided at each hanging position, but one hanger cable may be provided at each hanging position.

[0049] Furthermore, in the above embodiment, the existing hanger cable 4 is replaced with a new hanger cable 8 of the same configuration, but the new hanger cable may be replaced with one having a different configuration from the existing hanger cable 4. For example, by using a hanger cable itself equipped with a length adjustment mechanism and a tension introduction mechanism, the tension of the first and second temporary hanging members 10, 20 may be transferred to the new hanger cable without using the second jack 40.

[0050] Furthermore, in the above embodiment, the new connecting member 60 is attached to the connecting member 7, but the new connecting member 60 may be attached directly to the suspended structure 5.

[0051] Furthermore, in the above embodiment, a winding device 50 for winding up the second temporary hanging member 20 is installed on the suspended structure 5, but if the length of the second temporary hanging member 20 is short, the excess length of the second temporary hanging member 20 may be stretched and placed directly on the suspended structure 5 without using the winding device 50.

[0052] Furthermore, the above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment. [Explanation of symbols]

[0053] 1...suspension bridge, 3...main cable, 4...hanger cable, 5...suspended structure, 7...connecting member, 8...hanger cable, 10...first temporary suspension member, 20...second temporary suspension member, 30...first jack, 40...second jack, 50...winding device.

Claims

1. In a method for replacing an existing hanging member, the upper end of which is connected to the main cable side and the lower end of which is connected to the suspended structure side, with a new hanging member, a first temporary suspension member connected to the suspended structure side, a second temporary suspension member connected to the main cable side, a first tensioning device capable of applying tension between the first temporary suspension member and the second temporary suspension member, and a second tensioning device capable of applying tension between the first temporary suspension member and a portion of the suspension material excluding the lower end side, By applying tension between the portion of the existing hanging material excluding the lower end side and the first temporary hanging member using the second tensioning device, the tension on the lower end side of the existing hanging material is transferred to the second tensioning device and the first temporary hanging member, The connection between the bottom end of the existing hanging member, which is now in a tension-free state, and the hanging structure is released. By applying tension between the first temporary hanging member and the second temporary hanging member using the first tensioning device while reducing the tension between the first temporary hanging member and the portion of the existing hanging member excluding the lower end side using the second tensioning device, all of the tension of the existing hanging member is transferred to the first and second temporary hanging members, Replace the existing hanging material, which is now in a tension-free state, with a new hanging material. A method for replacing a hanging material.

2. After replacing the existing hanging material with a new hanging material, By applying tension between the first temporary hanging member and the portion of the new hanging member excluding the lower end side thereof using the second tensioning device while reducing the tension between the first temporary hanging member and the second temporary hanging member using the first tensioning device, the tension of the first and second temporary hanging members is transferred to the portion of the new hanging member excluding the lower end side thereof, the second tensioning device, and the first temporary hanging member; After connecting the lower end of the new hanging member to the hanging structure, The tension applied by the second tension applying device between the first temporary hanging member and the part of the new hanging member excluding the lower end side is released, thereby transferring the tension of the first temporary hanging member to the entire new hanging member.

2. The hanging material replacement method according to claim 1.

3. A minute tension is applied between the first temporary hanging member and the second temporary hanging member by the first tensioning device to tension the first temporary hanging member and the second temporary hanging member, and while the tension applied by the second tensioning device between the first temporary hanging member and a portion of the existing hanging material excluding the lower end side is reduced, tension is applied between the first temporary hanging member and the second temporary hanging member by the first tensioning device.

2. The hanging material replacement method according to claim 1.

4. The length of the second temporary hanging member is changed according to the length of the hanging material.

2. The hanging material replacement method according to claim 1.

5. A strand and a strand jack are used as the second temporary hanging member and the first tension applying device.

5. The hanging material replacement method according to claim 4.

6. A suspension member replacement device for replacing an existing suspension member, the upper end of which is connected to the main cable side and the lower end of which is connected to the suspended structure side, with a new suspension member, a first temporary suspension member connected to the suspension structure; a second temporary suspension member connected to the main cable side; a first tension applying device capable of applying tension between the first temporary suspending member and the second temporary suspending member; and a second tension applying device capable of applying tension between the portion of the hanging material excluding the lower end side and the first temporary hanging member. A hanging material replacement device characterized by the above.

7. The length of the second temporary hanging member can be changed according to the length of the hanging material.

7. The hanging material replacement device according to claim 6.

8. The second temporary hanging member and the sixth tension applying device are constituted by a strand and a strand jack.

8. The hanging material replacement device according to claim 7.

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