JP2018003526A - Replacement method for main cable of suspension bridge - Google Patents

Abstract

[PROBLEMS] To reduce the troublesome work as much as possible without suspending a temporary cable along the main cable prior to the removal of the main cable when replacing the main cable of the suspension bridge. Provide a cable replacement method. An oblique suspension cable 11 is stretched between a main tower 2 and a stiffening girder 5 of a suspension bridge 1 to hold the stiffening girder 5. In this state, the hanger rope 4 is disassembled and removed, and the main cable 3 is replaced. A new hanger rope 4 is suspended from the newly installed main cable 3, the stiffening girder 5 is supported on the hanger rope 4, and the stiffening girder 5 is held by the main cable 3. Thereafter, the oblique cable 11 is removed. Further, if necessary, an oblique suspension tower 13 is installed outside the main tower 2, and the oblique suspension cable 11 is spanned between the oblique suspension tower 13 and the stiffening girder 5 to provide the stiffening girder 5. Hold. [Selection] Figure 3

Description

  The present invention relates to a method for replacing a main cable of a suspension bridge that replaces a main cable of a suspension bridge that is spanned between a valley in a mountainous area or a cliff in Kawaguchi Bay.

  Suspension bridges are built on the bridges that are bridged to pass between the cliffs across the gorge and Kawaguchi Bay, because the bridge piers cannot be installed and are long spans. Various types of suspension bridges are installed, ranging from large ones intended for trains and cars to small ones intended for traffic. In particular, in the case of a pedestrian bridge intended for traffic of people in mountainous areas, a suspension bridge is frequently used because it does not require a large width traffic path.

  The suspension bridge mainly consists of a main cable passing through the top of the main tower installed on both sides of the valley, and a stiffening girder supported on the lower end of the hanger rope suspended from the main cable. Secure the end of the cable to the anchor block. Support both ends of the stiffening girder on the piers installed on both banks. A floor slab is installed on the stiffening girder to provide a walking path.

  For example, Patent Document 1 discloses an erection device used in a method for pulling out a suspension bridge stiffening girder using a sliding beam using a main cable. Patent Document 2 discloses a suspension bridge main cable erection method and apparatus capable of minimizing the length of a holing rope and the number of drive devices, improving work efficiency, shortening the work period, and reducing the work cost. Has been.

Japanese Patent Publication No. 22-22805 Japanese Patent Laid-Open No. 10-237819

  The main cable of the suspension bridge acts to transmit the loaded load to the anchor block. However, if the main cable becomes old and cannot maintain sufficient strength, it will not transmit force and will receive repeated loads. Therefore, it is necessary to replace the main cable.

  When replacing the main cable, the existing main cable is removed, but it is necessary to support the stiffening girder. In the structure of the suspension bridge, the stiffening girder is supported at the lower end of the hanger rope suspended from the main cable, so it is necessary to hold this hanger rope prior to the removal of the existing main cable. A temporary cable is installed and the hanger rope is held on the temporary cable. Moreover, a temporary iron tower for supporting this temporary cable is installed outside the main tower. While holding the hanger rope on the temporary cable and supporting the stiffening girder, remove the existing main cable. A new main cable is installed in place of the removed main cable, and a new hanger rope is suspended on the main cable to hold the stiffening girder. Then, the temporary cable and the temporary tower are removed. The above-described temporary cable erection and new main cable erection can be performed by the erection method disclosed in Patent Document 2, for example.

  However, since construction work is performed for each of the temporary cable and the new main cable, a complicated operation is required. Moreover, a construction period becomes long and there exists a possibility that the period when the use of a suspension bridge in the meantime is restrict | limited may become long.

  Accordingly, an object of the present invention is to provide a method for replacing a main cable of a suspension bridge that can reduce the construction period by minimizing complicated work.

  As a technical means for achieving the above object, the main cable replacement method for the suspension bridge according to the present invention is such that the stiffening girder is held on the hanger rope suspended by the main cable spanned between the main towers. In the method for replacing the main cable of the suspension bridge, the main cable is replaced by holding a stiffening girder over the main tower and the stiffening girder so as to hold the stiffening girder.

  The main cable can be released from the holding state of the stiffening girder by holding the stiffening girder in the main tower with the slanting cable. The stiffening girder is held by the slanting cable. In this state, the existing main cable is removed and a new main cable is routed between the main towers. A hanger rope is suspended from the newly installed main cable to support the stiffening girder on the hanger rope.

  According to a second aspect of the present invention, there is provided a method for replacing a main cable of a suspension bridge in which a stiffening girder is held on a hanger rope suspended by a main cable spanned between main towers. In the replacement method, the floor slab arranged on the stiffening girder is replaced, a slanting cable is bridged between the main tower and the stiffening girder to hold the stiffening girder, the hanger rope is removed, and the existing main spar is removed. The cable is replaced with a new main cable, a new hanger rope is attached, the stiffening girder is held by the new main cable, and the slanting cable is removed.

  The present invention relates to a case where other structural elements such as a floor slab are replaced together with replacement of the main cable. That is, after removing the existing floor slab from the stiffening girder, a new floor slab is installed, and the stiffening girder is held by spanning a slanting cable. Remove the hanger rope and remove the existing main cable. A new main cable is installed and a new hanger rope is attached, and a stiffening girder is supported by these. Next, the slanting cable is removed.

  According to a third aspect of the present invention, there is provided a method for replacing a main cable of a suspension bridge by installing a diagonal suspension tower outside the main tower, and replacing the main tower with the oblique suspension tower and the stiffening girder. It is characterized in that the slanting cable is stretched over.

  When a slanting cable is attached to an existing main tower and a stiffening girder is held, if there is a risk that sufficient strength cannot be obtained in the main tower, a slanting tower for attaching the slanting cable By installing, it is designed not to put a burden on the main tower.

  The main cable replacement method for the suspension bridge according to the invention of claim 4 is characterized in that an outer cable is disposed under the stiffening girder and the oblique suspension cable is connected to the outer cable. .

  If the stiffening girder cannot be stably held depending on the number of slanting cables and the mounting position on the stiffening girder, an outer cable is placed under the stiffening girder and the slanting cable is linked to this. Thus, the force applied to the slanting cable is dispersed so that the stiffening girder can be stably held.

  According to the method for replacing the main cable of the suspension bridge according to the present invention, the stiffening girder is held by the slanting cable prior to the replacement of the main cable. For this reason, the complicated work which constructs and installs a temporary cable is not performed, and the construction period required for the replacement work can be shortened.

It is a side view of a suspension bridge in the state which replaces a main cable. It is a side view of a suspension bridge which shows the state which replaces the floor slab installed in the stiffening girder. It is a side view of a suspension bridge which shows the state which bridges a slanting cable between a main tower and a stiffening girder. It is a side view of a suspension bridge which shows the state which removes a hanger rope. It is a side view of a suspension bridge which shows the state which replaces a main cable. It is a side view of a suspension bridge which shows the state which attaches a hanger rope. It is a side view of a suspension bridge which shows the state at the time of removing a slanting cable.

  Hereinafter, the method for replacing the main cable of the suspension bridge according to the present invention will be specifically described based on the illustrated embodiment.

  As shown in FIG. 1, the suspension bridge 1 has a main cable 3 installed on main towers 2, 2 provided on both sides, a hanger rope 4 is attached to the main cable 3, and the hanger rope 4 stiffens the hanger. Girder 5 is supported. Further, a floor slab 6 is placed on the stiffening girder 5 and a passage is installed.

  Prior to removing the main cable 3, the floor slab 6 and the rail are removed. At this time, when these loads are removed, the stiffening girder 5 and the like may be lifted by the tension of the main cable 3. In this case, the provisional support 8 is interposed between the stiffening girder 5 and the pier 7 to support the stiffening girder 5 in a lifted state.

  Next, as shown in FIG. 2, a new floor slab 9 is installed on the stiffening girder 5. In this case, for example, in the structure in which the concrete slab is installed on the floor slab 6 of the existing suspension bridge 1, it is possible to reduce the weight of the bridge body by changing this to a steel slab. Further, when installing the floor slab 9, it can be installed by pushing the heavy machine 10.

  With the floor slab 9 installed, as shown in FIG. 3, the slanting cable 11 is spanned between the main tower 2 and the stiffening girder 5 to hold the stiffening girder 5 on the main tower 2. In this case, the slanting cable 11 is preferably fixed to the lower chord member of the stiffening girder 5. Further, if necessary, an outer cable 12 is stretched under the stiffening girder 5 and a slanting cable 11 is connected to this to disperse the force applied to the slanting cable 11. Furthermore, a slanting tower 13 can be installed outside the main tower 2, and the slanting cable 11 can be supported by the slanting tower 13 instead of the main tower 2.

  As shown in FIG. 4, the hanger rope 4 is disassembled in a state where the slanting cable 11 is stretched. At this time, the vehicle is disassembled under load using the aerial work platform 15 and the temporary pulling rope 16. Reinforce as needed so that the strength of the truss sufficiently resists the dead load of the bridge body.

  After the hanger rope 4 is disassembled, the main cable 3 is replaced. As shown in FIG. 5, this attachment work involves disassembling the existing main cable 3 using the winch 14 and installing the new main cable 3.

  As shown in FIG. 6, a new hanger rope 4 is suspended from the newly constructed main cable 3, and the stiffening girder 5 is supported at the lower end thereof. At this time, the specifications of the hanger rope 4 are adapted according to the load of the newly installed floor slab 9.

  Thereafter, the slanting cable 11 is removed, and the slanting tower 13 installed as necessary is removed.

  According to the replacement method of the main cable of the suspension bridge according to the present invention, the installation work of the temporary cable is performed in order to install the oblique main cable and install the new main cable instead of the temporary cable installed along the existing main cable. The main cable replacement work can be performed with less troublesome work, so the construction period can be shortened and the cost required for the replacement work can be reduced to promote the replacement of the main cable of the suspension bridge. Contribute to.

1 Suspension bridge 2 Main tower 3 Main cable 4 Hanger rope 5 Stiffening girder 6 Floor slab 7 Bridge pier 8 Temporary support 9 Floor slab
10 heavy machinery
11 Angled cable
12 Outer cable
13 Oblique steel tower
14 Winch

Claims (4)

In the method of replacing the main cable of the suspension bridge in which the stiffening girder is held on the hanger rope suspended by the main cable spanned between the main towers,
A method for replacing a main cable of a suspension bridge, wherein a slant suspension cable is bridged between the main tower and the stiffening girder to hold the stiffening girder and the main cable is replaced. In the method of replacing the main cable of the suspension bridge in which the stiffening girder is held on the hanger rope suspended by the main cable spanned between the main towers,
Replace the floor slab placed on the stiffening girder,
Hold the stiffening girder over the main tower and the stiffening girder by hanging a slanting cable,
Remove the hanger rope,
Replace the existing main cable with the new main cable,
Attach a new hanger rope, hold the stiffening girder with the new main cable,
A method for replacing a main cable of a suspension bridge, wherein the oblique suspension cable is removed.   The oblique suspension steel tower is installed outside the main tower, and the oblique suspension cable is spanned between the oblique suspension steel tower and the stiffening girder instead of the main tower. The replacement method of the main cable of the suspension bridge according to Item 2.   The main cable of the suspension bridge according to any one of claims 1 to 3, wherein an outer cable is disposed below the stiffening girder, and the oblique cable is connected to the outer cable. Replacement method.

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