JPH1181237A - Beam drop preventing device for bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a beam from dropping from a bridge pier due to an earthquake by arranging buffer bodies made of a plate-like elastic body having a nearly triangular cross sectional shape at the beam hook section of the bridge pier fitted with the beam via a support body. SOLUTION: A beam 2 is supported on a support body 3, and the beam 2 is mounted and fixed to a beam hook section 1. Buffer bodies 6 made of a plate-like elastic body having a nearly triangular cross sectional shape and laminated and buried with a fiber body inside are arranged in a line or multiple lines with their tilt faces faced to the support body 3 in the axial direction of the beam hook section 1 and in the direction perpendicular to it around the support body 3. When an earthquake occurs and the support body 3 is shear-fractured, the beam 2 drops on a buffer body 6. When the beam 2 is further moved by aftershock, the beam 2 is moved upward on the tilt face of the buffer body 6 while breaking the fiber body in the buffer body 6. When movement of the beam 2 further proceeds, the beam 2 drops on the next buffer body, thereby earthquake energy is damped. The beam 2 can be prevented from dropping from a bridge pier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing a girder from falling off a pier due to an earthquake in a bridge.

[0002]

2. Description of the Related Art As a structure for preventing falling of a bridge girder on a highway or a railway due to earthquake vibration, there is a technology for connecting a girder using a reinforcing plate and a metal pin before the Hyogoken-Nanbu Earthquake. Techniques for connecting the girder with chains or cables have been used.

[0003]

However, in the prior art, the girder is installed to prevent the girder from dropping over the girder hook on the upper surface of the pier on which the girder is mounted.
The girder fell, causing the roads underneath to be completely closed, which was a major obstacle to subsequent recovery activities.

[0004] Further, assuming that seismic force and seismic energy are factors that cause the girder to fall due to an earthquake, a cushioning material for reducing the generated seismic force is effective against the seismic force.
As a cushioning material, the technology of a cushioning chain that utilizes the rubber damper function between the chains and a cushioning pin that covers the outer periphery of the pin with rubber has been developed, and its performance has been demonstrated in impact tests using connection parts and coupling parts It has been put to practical use.

On the other hand, since a member capable of absorbing as much energy as possible with respect to seismic energy is effective, a material in which a fibrous body is laminated and embedded in rubber is provided, and the above-mentioned cushioning chain or pin is used. A laminate has been proposed which is used as a cushioning material and breaks its fibrous body to increase the total amount of absorbed energy. However, since the seismic energy is enormous, these cushioning materials and laminates do not have enough energy absorption, and it is conceivable that the girder moves down the girder and falls.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a girder portion in which a girder is attached to a girder portion on the upper surface of a pier via a support body, and which is made of an elastic material having a substantially triangular cross section. The shock absorbers are arranged in at least one row so that the inclined surface faces the support body in a bridge axis direction around the support body and in a direction perpendicular to the direction of the bridge axis, and further, a fibrous body is laminated inside the buffer body. It is characterized by the following.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a plan view, FIGS. 2 to 5 are explanatory views showing an operation state, FIG. 6 is a cross-sectional view of a shock absorber, and in the figure, 1 is a girder portion on a pier upper surface, and 2 is The girder 3 is a bearing body for supporting the girder 2 on the girder hook portion 1 and is generally an elastic body 4 such as rubber or synthetic resin.
Are fixed to the girder 2 and the girder engaging portion 1 via the iron plate 5 with fixing members such as bolts. Therefore, the girder 2 is placed and fixed on the girder hook 1 via the support body 3.

Reference numeral 6 denotes a buffer, which is made of a plate-like elastic body having a substantially triangular cross-section, and is woven of natural fibers, synthetic fibers, and other fibers or metal in an elastic body 7 of rubber or synthetic resin. It has a structure in which a fibrous body 8 made of cloth, nonwoven fabric, net-like body or the like is buried and embeded integrally, and a rigid body 9 such as an iron plate is buried in the lower part as necessary. The cross-sectional shape is substantially a triangle having the inclined surface 10 as described above, and may be a shape in which a flat portion 11 is formed at the upper end as shown in FIGS. 7 and 8. It may be convexly curved, and the surface may not be a smooth surface but a non-slip surface such as a step. Further, the upper surface may be covered with a rigid body such as an iron plate.

The laminating direction of the fibrous body 8 may be any direction such as a state parallel to the bottom surface, a state parallel to the surface, and a state perpendicular to the bottom surface. Further, in a light beam structure such as a pedestrian bridge, an elastic body alone without the fibrous body 8 may be used. The fixing state of the buffer body 6 to the girder portion 1 may be fixed by a fixing tool such as a bolt, and furthermore, as shown in FIG. Any fixing structure such as a structure in which it is fitted and locked in the locking concave portion formed in the above.

As shown in FIG. 1, the shock absorbers 6 are arranged in a row in the bridge axis direction of the girder portion 1 around the support body 3 and in a direction perpendicular to the bridge axis so that the inclined surface faces the support body 3. Alternatively, a buffer in which a fibrous body is laminated and embedded in an elastic body in the same manner as the structure of the buffer 6 is provided between the support 3 and the buffer 6 and between the buffer 6 and the buffer 6 as necessary. Board 1
3 has a buffering effect. Also, the buffer plate 13
It goes without saying that the buffer members 6 may be arranged continuously without any intervening.

As described above, the support 3 of the girder 1
When the shock absorber 6 is disposed around the slab, if the earthquake occurs and the bearing member 3 is sheared and broken, the girders 2 fall on the shock absorbing plate 13 or the shock absorbing body 6 as shown in FIG. When the spar 2 moves further, the spar 2 moves while breaking the inner fibrous body 8 with the inclined surface of the buffer body 6 facing upward. If the movement still proceeds, the spar 2 is moved as shown in FIG. It will fall on the next buffer plate 13 or the buffer body 6.

The energy absorption in this case is the elastic strain energy of the buffer 6, the breaking energy of the fibrous body 8, and the potential energy falling from the buffer 6, and particularly the ratio of the potential energy is high as shown in FIG. There is a feature of the present invention in producing this energy decay, and the falling potential energy is a huge energy decay represented by Eh = W · h.

[0013] The attenuation of these energies makes it possible to prevent the girders in which the bearing body 3 has been sheared and broken from falling from the pier. Therefore, arranging the buffer 6 continuously has a large energy damping effect, and reduces the possibility that the spar falls from the spar portion on the upper surface of the pier. However, there is a structural limitation in making the girder portion large, and the installation amount of the buffer 6 depends on the size of the girder portion and the inclination angle and height of the inclined surface of the buffer 6. Is determined by

Although not related to the structure of the present invention, if a locking portion made of a rigid body made of concrete or the like is formed around the girder portion, the dropping safety of the girder is further improved. Second Embodiment In this embodiment, as shown in FIG.
The length of the buffer plate 13 is determined by the size of the buffer 6 according to the inclination angle and height of the inclined surface of the buffer 6.

Third Embodiment In this embodiment, a buffer 6 is formed so as to surround the support 3 at the girder portion. The buffer 6 is rectangular as shown in FIG. 11 or circular as shown in FIG. And any other shape. According to such a configuration, it is possible to cope with any direction and the mounting work becomes easy.

[0016]

According to the present invention described in detail above, a girder where a girder is attached to a girder on the upper surface of a pier via a bearing is made of a plate-like elastic body having a substantially triangular cross section. By arranging the shock absorbers in one or more rows in the direction of the bridge axis around the support and in the direction perpendicular to it, so that the inclined surface faces the support, an earthquake occurs and the support is sheared and destroyed. When the girder moves, the girder ends move with the inclined surface of the buffer facing upward while attenuating the seismic energy by the elastic strain energy of the buffer, and if still moving, drop from the buffer This has the effect of preventing the girder from falling off the pier by further attenuating the seismic energy.

Further, in the structure in which the fibrous body is laminated inside the buffer, the seismic energy can be further attenuated by the destructive energy of the fibrous body, so that a further damping effect can be expected.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment.

FIG. 2 is an explanatory diagram showing an operation state.

FIG. 3 is an explanatory diagram showing an operation state.

FIG. 4 is an explanatory diagram showing an operation state.

FIG. 5 is an explanatory diagram showing an operation state.

FIG. 6 is a cross-sectional view of a shock absorber.

FIG. 7 is a cross-sectional view showing another example of a shock absorber.

FIG. 8 is a cross-sectional view showing another example of a buffer.

FIG. 9 is a graph showing energy decay.

FIG. 10 is a cross-sectional view of a shock absorber according to a second embodiment.

FIG. 11 is a plan view of a shock absorber according to a third embodiment.

FIG. 12 is a plan view of a shock absorber according to a third embodiment.

[Explanation of symbols]

 1 girder part 2 girder 3 support 6 buffer 6 elastic body 8 fibrous body 9 rigid body 10 inclined surface 11 flat part 12 locking part 13 buffer plate

Claims (5)

[Claims] The present invention relates to a girder where a girder is attached to a girder on the upper surface of a pier via a support, and a cushion made of an elastic material having a substantially triangular cross section is provided around the support. A girder fall prevention device for a bridge, wherein at least one row is arranged so that an inclined surface faces a bearing body in a bridge axis direction and a direction orthogonal thereto. 2. The girder drop prevention device for a bridge according to claim 1, wherein a fibrous body is laminated inside the buffer. 3. The girder fall prevention device for a bridge according to claim 1, wherein a buffer plate is disposed at a front portion of the buffer body on the support body side. 4. The girder fall prevention device for a bridge according to claim 1, wherein a buffer is disposed so as to surround a support of the girder hanging portion. 5. The girder fall prevention device for a bridge according to claim 1, wherein an upper surface of the buffer is covered with a plate made of a rigid body.