JP3046929B2 - Bridge seismic isolation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation structure for reducing seismic force applied to a pier of a bridge product.

[0002]

FIG. 12 is a side view of a bridge according to the prior art.
FIG. 13 is an enlarged cross-sectional view taken along line FF of FIG.

[0003] As shown in both figures, the bridge girder of the conventional bridge is:
It is supported by a shoe 5 having a spherical bottom surface provided between the main girder 1 supporting the floor slab 3 and the pier 4. Shoes 5
There are a fixed shoe and a movable shoe, but the movable shoe absorbs the elongation due to the temperature of the bridge girder, and the bridge girder is basically fixed to the pier 4.

In the conventional bridge, since the bridge girder is fixed to the pier 4 as described above, at the time of an earthquake, the inertia force of the bridge girder (mass of the bridge girder × the seismic acceleration) remains unchanged.
And the excessive bending moment acts on the base of the pier 4 to cause breakage.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a seismic isolation structure for a bridge that can prevent damage to a bridge pier, a bridge girder, or the like during an earthquake.

[0005]

A first aspect of the present invention for achieving the above object is as follows.
Seismic isolation of a bridge of the invention is the bridge axis direction between the bridge girder and pier
And a structure in which the bridge girder can slide on the pier in the bridge axis direction and the bridge axis perpendicular direction, and is flexible and plastically deformed. The possible stopper is the energy absorption capacity by its plastic deformation.
The range of movement of the bridge girder is controlled by force to
It is characterized by being arranged so as to prevent large displacement.

According to a second aspect of the present invention , there is provided a seismic isolation structure for a bridge, wherein the bridge girder is supported by a laminated rubber interposed between the bridge girder and the pier, and a friction damper is provided between the bridge girder and the pier. It is arranged diagonally to the direction, the direction perpendicular to the bridge axis and the vertical direction. Also, the seismic isolation structure of the bridge according to the third invention.
In the seismic isolation structure for a bridge according to the first invention,
PA changes the thickness of the two stoppers to reduce the collision force
It is characterized by being gradually strengthened.

[0007]

According to the first aspect of the invention, the bridge pier and the bridge girder can be relatively displaced by sliding in the direction of the bridge axis and in the direction perpendicular to the bridge axis during an earthquake, and the frictional force during sliding and the spring force Only power works. This frictional force becomes the damping force of the vibration system formed by the bridge girder and the pier, and reduces the response of the system during an earthquake. The movement range of the bridge girder at the time of the slip is controlled by the stopper.

According to the second aspect of the invention, the pier and the bridge girder can be displaced relative to each other in the direction of the bridge axis and in the direction perpendicular to the bridge axis during an earthquake. Only the frictional force of the friction damper works. Therefore, the load acting on the tip of the pier is greatly reduced as compared with the conventional art, and the friction damper acts as a damping force of the vibration system composed of the pier and the bridge girder, so that the response of the system during an earthquake is reduced. According to the third aspect, the stopper is plastically deformed.
Two stoppers are used to prevent excessive displacement of the bridge girder by
By changing the plate thickness, the collision force at the time of collision gradually increases
It becomes.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same parts as those in the prior art are denoted by the same reference numerals.

<First Embodiment> FIG. 1 is a side view of a bridge according to a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG. 1, and FIG. FIG. 4 is an enlarged cross-sectional view taken along line B of FIG. 2, FIG. 4 is an enlarged cross-sectional view of a portion C in FIG. 2, and FIG.

As shown in FIGS. 1 to 3, a mounting bracket 12 provided between the main girders 1 at the top end 20 of the pier 4 and a mounting bracket 13 provided at the corners of the main girder 1 and the horizontal girder 2 are provided. The coil springs 11 are disposed between the coil springs 11, and these coil springs 11 are inclined with respect to three directions of a bridge axis direction, a direction perpendicular to the bridge axis, and a vertical direction.

As shown in FIG. 4, a sliding shoe 14 is provided below the main girder 1, and a sliding plate 1 is mounted on the top end 20 of the pier 4.
5 are provided. The sliding shoe 14 is installed on a sliding plate 15 and is covered by a cover 16 and a dustproof cover 19. A stopper 17 having a small thickness and a stopper 18 having a large thickness are cantilevered in the cover 16.

Therefore, according to the bridge according to the first embodiment having the above structure, the coil springs 11 are arranged obliquely to the three directions between the bridge girder and the pier 4 and are provided at the pier top 20. Since the sliding shoe 14 is installed on the sliding plate 15, the pier 4 and the bridge girder can be relatively displaced by the sliding in the bridge axis direction and the direction perpendicular to the bridge axis and prevent the bridge girder from rising during an earthquake. Therefore, only the frictional force during sliding and the spring force act on the tip of the pier. Further, this frictional force becomes a damping force of the vibration system formed by the bridge girder and the pier 4, and reduces the response of the system during an earthquake.

FIG. 5 shows an example of a frequency response curve of this system. In the seismic isolation structure of the bridge according to the first embodiment, the displacement of the pier top 20 or the stress of the pier base is compared with the conventional structure. It can be reduced to 1/4 to 1/6.

In order to prevent excessive displacement of the bridge girder, a stopper 17 and a stopper 18 are provided on the cover 16 of the sliding shoe 14, and the cover 16 functions as a further excessive displacement prevention. The mounting bracket 12 functions as a fall prevention device. Stopper 17 and stopper 1
8 is to change the plate thickness to gradually increase the collision force at the time of collision and to make the cantilever easily deformable, to have an energy absorbing ability by plastic deformation, and to prevent excessive displacement of the bridge girder.

From the above, the damage of the bridge pier 4, the damage of the sliding shoe 14, and the main girder 1 of the sliding shoe mounting portion at the time of the earthquake.
Can be prevented from being damaged.

<Second Embodiment> FIG. 6 is a side view of a bridge according to a second embodiment of the present invention, FIG. 7 is an enlarged cross-sectional view taken along line DD of FIG. 6, and FIG. FIG. 9 is a sectional view showing an example of a friction damper, FIG. 10 is a partially broken side view showing an example of a laminated rubber, and FIG. 11 is a view showing the effect of the bridge according to the second embodiment. FIG.

As shown in FIGS. 6 to 8, the main girder 1 of the bridge girder
The main girder 1 is supported by the laminated rubber 24 interposed between the main girder 4 and the pier 4. Further, friction dampers 21 are provided between a mounting bracket 22 provided between the main girders 1 at the top end of the pier 4 and a mounting bracket 23 provided at the corners of the main girder 1 and the horizontal girder 2. These friction dampers 21 are inclined with respect to three directions of a bridge axis direction, a direction perpendicular to the bridge axis, and a vertical direction.

The friction damper 21 and the laminated rubber 24 used here are commercially available products, and an example of their structure is shown in FIGS. 9 and 10. In a friction damper 21 shown in FIG. 9, a rod 21d is inserted into an outer cylinder 21a, and a friction ring 21b is provided between a distal end side and a proximal end side of the rod 21d.
A holding plate 21c and a disc spring 21e are provided. Further, the laminated rubber 24 shown in FIG.
The iron plates 24b and the rubbers 24c are alternately laminated between them.

Therefore, according to the bridge according to the second embodiment having the above structure, the laminated rubber 24 supporting the bridge girder is made of a steel plate 24b.
Since the rubber and the rubber 24c are alternately laminated, it is possible to withstand a high load and to allow a large shear deformation. Also,
Since the friction dampers 21 are arranged obliquely between the bridge girder and the pier 4 with respect to the bridge axis direction and the direction perpendicular to the bridge axis, and the mounting portion is a spherical bearing, the bridge pier 4 and the bridge girder are connected to each other in an earthquake. Relative displacement in the direction and in the direction perpendicular to the bridge axis, and only the restoring force of the laminated rubber 24 at the time of shear deformation and the friction force of the friction damper 21 act on the tip of the pier. Therefore, the load acting on the tip of the pier is greatly reduced, and the friction damper 21
Acts as a damping force of the vibration system composed of the pier 4 and the bridge girder, and the response of the system during an earthquake is reduced.

FIG. 11 shows an example of a frequency response curve of this system. In the seismic isolation structure for a bridge according to the second embodiment, the displacement of the pier top or the stress at the pier root is reduced by 1 / compared to the conventional structure. It can be reduced to 3 to 1/4. Also,
The mounting bracket 22 increases the distance from the end of the girder to the top edge of the pier, which also functions as bridge prevention.

<Third Embodiment> A bridge according to a third embodiment is as follows.
In FIG. 1, both outer main girders 1 have the configuration of the coil spring 11, the sliding shoe 14, and the sliding plate 15 as in the first embodiment, and the inner two main girders 1 have the same structure as in the second embodiment. First, the laminated rubber 24 and the friction damper 21 are configured.

Accordingly, in the bridge according to the third embodiment having the above-described structure, the operation of the first embodiment is the same at the outer main girder 1 on both sides, and the operation of the second embodiment is performed at the inner two main girder 1. This is the same as the operation of the example. The effect of the third embodiment is approximately intermediate between the effect of the first embodiment and the effect of the second embodiment.

[0024]

According to the present invention, the seismic force acting on the pier during an earthquake can be reduced and damage to the pier and main girder can be prevented. be able to. Therefore, damages such as restoration work and distribution until restoration can be prevented.

In addition, it is not necessary to reinforce the bridge pier excessively and to increase the strength, and it is possible to reduce the cost of the viaduct.

[Brief description of the drawings]

FIG. 1 is a side view of a bridge according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along line AA of FIG.

FIG. 3 is an enlarged cross-sectional view taken along the line BB of FIG. 1;

FIG. 4 is an enlarged cross-sectional view of a portion C in FIG. 2;

FIG. 5 is an explanatory diagram showing an effect of the bridge according to the first embodiment of the present invention.

FIG. 6 is a side view of a bridge according to a second embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view taken along line DD in FIG. 6;

FIG. 8 is an enlarged cross-sectional view taken along line EE in FIG. 6;

FIG. 9 is a cross-sectional view illustrating an example of a friction damper.

FIG. 10 is a partially broken side view showing an example of a laminated rubber.

FIG. 11 is an explanatory diagram showing an effect of the bridge according to the second embodiment of the present invention.

FIG. 12 is a side view of a bridge according to the related art.

FIG. 13 is an enlarged cross-sectional view taken along line FF of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main girder 2 Cross girder 3 Floor slab 4 Bridge pier 11 Coil spring 12 Mounting bracket 13 Mounting bracket 14 Slip shoe 15 Slip board 16 Cover 17 Stopper 18 Stopper 19 Dustproof cover 20 Bridge pier top end 21 Friction damper 22 Mounting bracket 23 Mounting bracket 24 Lamination Rubber

Claims (3)

(57) [Claims] 1. A bridge axis direction between a bridge girder and a pier, at a right angle to the bridge axis.
A spring is disposed obliquely to the direction and the vertical direction, and the bridge girder has a structure capable of sliding on the pier in the bridge axis direction and the direction perpendicular to the bridge axis, and a flexible and plastically deformable stopper , A seismic isolation structure for a bridge, wherein the bridge girder is disposed so as to prevent an excessive displacement of the bridge girder by controlling a range of movement of the bridge girder by an energy absorbing ability by the plastic deformation . 2. The bridge girder is supported by a laminated rubber interposed between the bridge girder and the pier, and a friction damper is provided between the bridge girder and the pier in a bridge axis direction, a direction perpendicular to the bridge axis, and a vertical direction. A seismic isolation structure for bridges, which is installed diagonally. 3. The seismic isolation structure of a bridge according to claim 1,
And The stopper changes the thickness of the two stoppers during a collision.
Characterized by gradually increasing the collision force of
Seismic isolation structure of bridge.