JP7121543B2 - Fall prevention device for side blocks in bridge bearings - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fall prevention device for a side block in a bridge bearing.

Bearings are installed between the upper and lower structures of a bridge to support the load of the upper structure, allow rotation due to deflection, and follow expansion and contraction due to temperature changes. In addition, side blocks are provided on both sides of the bearing in the bridge axis direction to limit the movement of the bearing in the direction perpendicular to the bridge axis during an earthquake.

In such a bridge bearing, if the side block restricts the movement of the bearing against a horizontal force exceeding a predetermined level due to seismic motion, excessive force will be applied to the lower structure such as the bridge piers, resulting in damage. For this reason, the bolts that secure the side blocks to the lower structure are designed to break when a horizontal force exceeding a predetermined level is applied to the side blocks, preventing excessive force from being applied to the lower structure.

If the bolts that secure the side blocks break, the side blocks can be released and fall from the top of the undercarriage. Falling side blocks can result in damage to vehicles traveling on the road beneath the bridge and injury to pedestrians. In order to prevent the side block from falling, conventionally, a countermeasure has been taken in which a chain is attached to the side block and the end of the chain is fixed to the lower structure (see, for example, paragraph 0006 of Patent Document 1). .

However, the conventional countermeasures described above are not only prone to rusting due to the use of a metal chain, but also, if the metal chain comes into contact with the bearing, the paint on the bearing is easily peeled off and damaged, and the metal chain is heavy. There are difficulties in transportation and installation. In addition, a pair of side blocks are installed on both sides of the bearing in the direction of the bridge axis. Chains are attached to each side block and the ends of the chains are fixed to the substructure, which takes time to install. There is also a problem.

JP 2007-64413 A

The present invention was made based on the above technical background, and achieves the following objects.
SUMMARY OF THE INVENTION An object of the present invention is to provide a fall prevention device for a side block which uses lightweight members, is easy to transport, and is easy to install.

In order to achieve the above object, the present invention employs the following means.
That is, the present invention comprises a bearing installed between an upper structure and a lower structure, and a pair of side blocks installed on both sides of the bearing in the bridge axis direction to limit the movement of the bearing in the direction perpendicular to the bridge axis. At the bridge bearing,
A bearing, a side block, and a flexible resin material, characterized in that the pair of side blocks are connected to each other by a resin flexible strip formed in a loop shape so as to surround the bearing. A fall prevention device for a side block in a bridge support portion , which is composed of a striation .

More specifically, it is possible to employ a configuration in which the flexible strips are supported by hangers attached to each of the side blocks.

In addition, the flexible strip can adopt a structure made of a hollow braided rope.

According to the side block drop prevention device of the present invention, the members used are lightweight and easy to transport, and the mounting work can be easily performed.

It is the front view which showed embodiment of this invention and looked at the bridge axis direction of the bridge support part. It is a top view of the same support part. FIG. 4 is a plan view showing a braid rope used as a flexible resin strip. FIG. 4 is a plan view showing connecting portions at both ends of a flexible strip;

Embodiments of the present invention will be described below with reference to the drawings. The illustrated embodiment is an example in which the present invention is applied to a bridge bearing portion in which a rubber bearing 10 is installed between an upper structure (bridge girder) 14 and a lower structure (pier or abutment) 15 . FIG. 1 is a front view of a bridge bearing viewed in the direction of the bridge axis, and FIG. 2 is a plan view of the bearing.

The rubber bearing 10 comprises an upper shoe 11, a lower shoe 12 and a rubber shoe 13 arranged between the upper and lower shoes 11,12. Both the upper shoe 11 and the lower shoe 12 are made of rectangular steel plates. The rubber shoe 12 is composed of a laminated rubber body obtained by laminating a rubber layer and a steel plate.

The upper shoe 11 is fixed to the lower surface of the upper structure 14 with bolts via a sole plate (not shown). A shear key 16 provided in the center of the upper surface of the upper shoe 11 is fitted into a key hole provided in the sole plate, and the horizontal force of the upper structure 14 is transmitted to the rubber bearing 10 via this shear key 16. be.

A base plate 17 made of a steel plate is fixed to the upper surface of the lower structure 15 via anchor bolts (not shown). The lower shoe 12 is fixed on this base plate 17 with a large number of bolts 18 . A pair of side blocks 19 , 19 are arranged on both sides of the rubber bearing 10 in the bridge axis direction and fixed to the upper surface of the base plate 17 with bolts 20 .

The side blocks 19, 19 are composed of a rectangular parallelepiped base 19a and a projection 19b rising from the center of the base 19a. The projection 19b has a height reaching the end face of the upper shoe 11 along the bridge axis direction and is close to the end face. As a result, even if a horizontal force perpendicular to the bridge axis acts on the upper structure 14, the upper shoes 11 are received by the side blocks 19, so movement of the upper structure 14 in the direction perpendicular to the bridge axis is restricted.

A pair of side blocks 19, 19 are connected to each other by flexible strips 21 made of resin such as polyester. The flexible strip 21 is formed in a loop shape and arranged so as to surround the rubber bearing 10 . As the flexible strip 21, more specifically, as shown in FIG. 3, a hollow braid rope made by weaving a bundle of resin fibers such as polyester is used. This braided rope, for example, manufactured by Maeda Kosen Co., Ltd., can be used, has energy absorption performance, and has been shown in an accelerated durability test that there was no clear decrease in yield strength even after exposure for 35 years. Confirmed.

Eyebolts 22, which are annular hangers, are provided on the outer surfaces of the projections 19b of the side blocks 19, 19, respectively. A flexible strip 21 is supported by passing through these eyebolts 22 . A hook eye bolt, an open eye bolt, a Marukan bolt, an eye nut, a swivel, or the like can also be used as the ring-shaped hanging tool, in addition to the eye bolt.

If the rubber bearing 10 is already installed, the flexible strips 21 are attached to the side blocks in the following manner. First, tap holes are machined in the projections 19b of the side blocks 19, 19, and the eyebolts 22 are screwed into the tap holes. Next, a single flexible strip 21 having a required length is passed through the eyebolts 22 of the side blocks 19, 19, and both ends of the flexible strip 21 are fixed to form a loop, thereby forming a rubber bearing 10. surround the

When the loop-shaped flexible strip 21 is reduced in size and placed in tension, it affects the shear deformation of the rubber bearing 10 in the bridge axis direction. , and is laid on the base plate 17 as shown in the drawing.

Both ends of the flexible strip 21 can be fixed as shown in FIG. The hollow braided cord rope 21, which is a flexible strip, has a property that its diameter increases when it is contracted in the axial direction. Using this property, one end 21a of the braided rope 21 (suitable length range) is shortened to increase the diameter. Then, the other end portion 21b is inserted into the one end portion 21a having a larger diameter, the mesh of the one end portion 21a is opened, and the other end portion 21b is pulled out. The other end pulled out through the mesh is provided with a knot 23 with a larger diameter for preventing it from coming off, for example, by knotting it. This braided rope can be easily cut to the required length with scissors on site and used.

When tensile force acts on both ends of the braided rope 21 fixed in this way, the diameter of one end 21a becomes smaller and the frictional force generated between the other end 21b becomes larger. , the other end 21b does not slip out, and the fixed state of both ends 21a and 21b is maintained.

In the bearing portion as described above, a horizontal force greater than or equal to a predetermined level acts on the superstructure 14 due to an earthquake motion. 19 is released.

Here, if only one side block 19 is released from the fixation, this one side block 19 is connected to the other fixed side block 19 through the flexible strip 21. Therefore, it does not fall from the lower structure 15. Further, even if the fixing of both side blocks 19, 19 is released, the side blocks 19, 19 are connected to each other, and the rubber bearing 10 is interposed between the side blocks 19, 19. Neither of the side blocks 19, 19 falls off the lower structure 15 with the support 10 as a support. That is, the cooperation of the pair of side blocks 19, 19 prevents them from falling.

According to this invention, since the resin flexible strip 21 is used to connect the side blocks 19, 19, unlike steel wire ropes or metal chains, it is lightweight and easy to transport. In addition, since it does not rust, it has excellent durability and does not adversely affect the coating of the bearing. When attaching the flexible strip 21, the sling 22 is attached to the side blocks 19, 19, and the flexible strip 21 is passed through the sling 22 and both ends are connected to form a loop. can also be done easily.

If a steel wire rope is used instead of a resin flexible strip such as the above-mentioned braided rope, the required length is measured on site for each size of the bearing, and cut to this length at the factory. After that, terminal processing must be done. There are wire clip processing, eye splice processing, sleeve compression processing, etc. for this terminal processing method, but wire clip processing changes the fastening force depending on the tightening force of the bolt, making it difficult to manage. On-site construction is generally difficult. Also, when connecting this as a single small rope, it will be connected with a U-shaped bolt or the like. Since a margin is required, it cannot be applied to small bearings.

In the above-described embodiment, an example in which the present invention is applied to a bearing provided with a rubber bearing has been shown, but the present invention can also be applied to other types of bearing provided with side blocks, such as a bearing provided with a roller bearing. Applicable. Also, if the weight of the side block is large, a double looped flexible strip can be used.

Further, the present invention can be applied not only to the existing support of the support portion but also to the newly installed one. In the case of newly installed bearings, lateral holes for passing the flexible strips may be integrally formed in the side blocks in advance.

10: Rubber bearing 11: Upper shoe 12: Lower shoe 13: Rubber shoe 14: Upper structure 15: Lower structure 17: Base plate 19: Side block 21: Resin flexible strip (braid rope)
22: Suspension tool 23: Tub (stop knot)

Claims (3)

A bridge bearing section comprising a bearing installed between a superstructure and a substructure, and a pair of side blocks installed on both sides of the bearing in the bridge axis direction to limit the movement of the bearing in the direction perpendicular to the bridge axis,
A bearing, a side block, and a flexible resin material, characterized in that the pair of side blocks are connected to each other by a resin flexible strip formed in a loop shape so as to surround the bearing. A fall prevention device for a side block at a bridge support, which is composed of a strut. 2. A fall prevention device for side blocks in a bridge support according to claim 1, wherein said flexible strips are supported by slings attached to each of said side blocks. 3. A fall prevention device for a side block in a bridge bearing according to claim 1, wherein said flexible strip comprises a hollow braided rope.

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