JPH10266128A - Bridge pier structure of highway bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage of a bridge pier body, by arranging a buffer on an anchor frame in the bridge pier base and installing the bridge pier body on the buffer and connecting and fixing the buffer by fixing members piercing the buffer from the pier body and connecting them to the anchor frame. SOLUTION: Steel plates are put on the upper and lower faces of a synthetic rubber plate and these are laminated to form a plurality of layers and constitute a buffer laminated body 14. And the buffer laminated body 14 is arranged in the containing space 15 on the anchor frame 13 and the pier body 16 is erected on the buffer laminated body 14 and the lower steel plate 22a is integrally connected and fixed to the frame 13 and the upper steel plate 22b is integrally connected and fixed to the lower end of the pier body 16. And further, anchor bolts connected to the frame 13 at the lower end are inserted in a plurality of through holes formed on the synthetic rubber plates and the steel plates respectively to fix them with nuts. When vertical earthquake vibration arises, vertical stress wave spreads from the footing 12 to the pier body 16 but it is attenuated by the elasticity of the laminated body 14. And hence, buckling or breakage brought in the bridge pier body 16 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pier structure for a highway bridge or a general road bridge.

[0002]

2. Description of the Related Art Conventionally, damage to road bridge piers due to an earthquake is as follows.
As shown in FIG. 5 (a), there is an example of damage caused by an oceanic earthquake due to horizontal ground motion, and damage 3 has occurred at the base of the pier body 1 where the bending moment is maximum.

Meanwhile, damage to road piers caused by the 1995 Hyogoken-Nanbu Earthquake, as shown in FIGS.
It occurs concentrated in the central part and the upper part of the pier main body 1, and in some cases, it is buckled and destroyed. These are different from the conventional rupture, shear, and bending / shear failures caused by ocean-type earthquakes.
It is thought to be due to vertical ground motion from. In other words, the initial stress wave is generated in the pier base 2 by the vertical earthquake motion,
A part of the stress wave is reflected on the upper surface of the pier base 2, and the other part is transmitted from the pier base 2 to the pier body 1. FIG. 6 shows the relationship between the reflected stress wave and the transmitted stress wave at this time.
(A) and (b) show.

Since the average cross-sectional area ratio between the pier base 2 and the pier body 1 is generally considered to be about 0.1, FIG.
According to (b), the stress wave transmitted from the pier base 2 to the pier main body 1 is estimated to be about 1.8 times the vertical stress wave.

[0005]

By the way, as a countermeasure against a conventional road bridge earthquake, the design horizontal seismic intensity is 0.10 to 0.35 (according to the local ground conditions) in the specification for steel road bridges in 1964. Calculation)), and the standard vertical seismic intensity was 0.1.

In the seismic design guidelines of 1972, the modified seismic intensity method was adopted. The basic horizontal seismic intensity was multiplied by 0.2 to give a width of 0.10 to 0.24 by applying a correction coefficient. It is not to be considered. However, the vertical bearing seismic intensity was set to 0.1 as the standard, and seismic design and measures to prevent bridges were incorporated based on past seismic experience.

Further, in the enactment of 1980, the inspection of deformation performance and the inspection of horizontal strength possessed in the event of an earthquake in 1990 were specified, but the vertical seismic intensity is not considered in principle. However, for the design of the bearing, the standard vertical seismic intensity is 0.1.

As described above, the vertical load is not considered except for individual parts such as the bearing part. still,
The horizontal bearing capacity at the time of the earthquake was for reinforced concrete piers and was not specified for steel piers.

As a result, in the 1995 Hyogoken-Nanbu Earthquake, which is a city-underground earthquake, horizontal and vertical motions with high seismic intensity occurred simultaneously, causing extremely large damage to the piers of road bridges.

The first aspect of the present invention solves the above problems and provides a pier structure of a road bridge capable of effectively mitigating damage to a pier against a shocking vertical earthquake motion. Aim.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, a buffer is arranged on an anchor frame in a pier base to expose a surface thereof, and the surface of the buffer is mounted on the anchor frame. The pier body is installed in the pier body, and is connected and fixed by a fixing member that penetrates the buffer from the pier body and is connected to the arcer frame.

According to the above structure, the vertical stress wave transmitted from the pier base to the pier body is alleviated and transmitted by the buffer, so that damage to the pier body is reduced, and the vertical stress wave is transmitted to the middle or upper part of the pier body. Reduces damage such as buckling and destruction that occurs,
Can be prevented.

According to a second aspect of the present invention, the shock absorber is formed by alternately stacking a steel plate and a synthetic rubber plate.
According to the above configuration, the strength of the synthetic rubber plate can be increased by the steel plate, and the vertical impact due to the earthquake can be effectively reduced by the elastic force of the synthetic rubber plate.

Further, in the invention according to claim 3, the above-mentioned shock absorber is a buckling structure which buckles at a predetermined pressure. According to the above configuration, since the buckling structure can buckle and absorb its kinetic energy by applying a predetermined or more impact force, the vertical stress wave is reduced, and the intermediate portion of the pier body is Damage such as buckling or destruction occurring at the upper part or the upper part can be effectively reduced or prevented.

Further, in the invention according to a fourth aspect, the shock-absorbing member is replaceably disposed in a housing space formed on the anchor frame of the pier base. According to the above configuration, the pier can be repaired in a short time by lifting the pier and exchanging the damaged buffer, and the disconnection of the traffic network can be eliminated in a short time.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reinforced concrete pier of a road bridge according to the present invention will be described with reference to FIGS.

An anchor frame 13 is built in a footing 12 which is a pier base fixed to the foundation pile 11, and a housing space 15 for a buffer 14 is formed above the anchor frame 13. In this storage space 15, a buffer laminate 14 as a buffer is disposed so as to be replaceable.
A pier main body 16 is erected and fixed on the buffer body 14.

The buffer laminate 14 is formed by laminating a plurality of layers on the upper and lower surfaces of a synthetic rubber plate 21 with a steel plate 22 interposed therebetween.
It is configured such that the strength of the synthetic rubber plate 21 is increased and the elastic force acts effectively. The lower steel plate 22a of the steel plates 22 is integrally connected and fixed to the anchor frame 13, and the upper steel plate 22b is integrally connected and fixed to the lower end of the pier body 16. Furthermore, synthetic rubber plate 21
And an anchor bolt 23 having a lower end connected to the anchor frame 13 in a plurality of through holes formed in the steel plate 22.
Are respectively inserted and fixed by nuts 24. Therefore, as shown by phantom lines in FIG.
The upper steel plate 22b and the lower steel plate 22 are removed by removing the nut 24 and jacking up the pier body 16.
The buffer laminate 21 between a can be replaced.

According to the above-described embodiment, when a vertical ground motion occurs due to a direct earthquake, the footing 1
2 to the pier body 16 via the anchor frame 13 and the buffer laminate 14. Although several times the vertical stress wave is transmitted, the vertical stress wave is relieved by the elasticity of the buffer laminate 14, so that the load on the pier body 16 in the vertical direction can be reduced and the pier body 16 is generated. Buckling and destruction can be prevented beforehand.

FIG. 3 and FIG.
It is what it was. That is, between the lower pressing plate 31 integrally connected and fixed to the anchor frame 13 and the upper pressing plate 32 integrally connected and fixed to the lower end of the pier body 16,
A plurality of cylindrical members 33, which are buckling members whose upper end and lower end are narrowed down to have a small diameter, are erected and fixed at a constant pitch, the buckling strength of these cylindrical members 33 is calculated in advance to a predetermined value, and the buckling structure The buckling value for the vertical load of the body 31 is set to a predetermined value. The lower pressure plate 31 and the upper pressure plate 32 are fixed by nuts 35 through a plurality of anchor bolts 34 whose lower ends are connected to the anchor frame 13, and are configured to be replaceable.

In the above configuration, when a vertical ground motion occurs due to a vertical earthquake, the vertical stress wave is transmitted to the pier body 16 from the footing 12 via the anchor frame 13 and the buckling structure 30 for about 1. Although several times the vertical stress wave is transmitted, when the impact force exceeds a predetermined value that can destroy the pier body 16, the cylindrical body 33 buckles evenly,
By absorbing the kinetic energy, the load on the pier body 16 can be greatly reduced. This allows the pier body 13
Buckling and destruction that occur in the vehicle can be prevented.
At this time, the pier main body 16 is slightly lowered due to buckling, but can be easily absorbed by the connection structure between the pier main body 16 and the bridge girder.

[0022]

As described above, according to the first aspect of the present invention, the vertical stress wave transmitted from the pier base to the pier main body is relaxed and transmitted by the buffer, so that the pier main body is transmitted. Can be reduced, and damage such as buckling or destruction occurring in the middle and upper portions of the pier body can be reduced and prevented.

According to the second aspect of the present invention, the strength of the synthetic rubber plate can be enhanced by the steel plate, and the vertical impact due to the earthquake can be effectively reduced by the elastic force of the synthetic rubber plate. .

According to the third aspect of the present invention, the buckling structure can buckle and absorb its kinetic energy when an impact force of a predetermined level or more is applied. Thus, damage such as buckling or breakage occurring at the middle or upper part of the pier body can be effectively reduced and prevented.

According to the fourth aspect of the present invention, the pier is lifted to replace the damaged cushion,
The pier can be repaired in a short time, and the disruption of the transportation network can be resolved in a short time.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of a pier of a road bridge according to the present invention.

FIG. 2 is a sectional view showing a configuration of the buffer laminate.

FIG. 3 is a cross-sectional view illustrating a buckling structure according to another embodiment of the shock absorber.

FIG. 4 is a perspective view showing the buckling structure.

5 (a) to 5 (c) show destruction modes due to an earthquake on a pier of a road bridge, (a) shows an example of damage caused by an oceanic earthquake, and (b) and (c) show examples of damage directly under a city. .

6A is a graph showing the transmittance and the reflectance of a stress depending on the area ratio of a connection portion, and FIG. 6B is a graph showing an enlarged main part thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Footing (base of pier) 13 Anchor frame 14 Buffer laminated body 15 Housing space 16 Pier main body 21 Synthetic rubber plate 22 Steel plate 23 Anchor bolt 24 Nut 30 Buckling structure 31 Lower press plate 32 Upper press plate 33 Cylindrical body 34 Anchor bolt 35 nut

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Miyashita 5-3-28 Nishikujo, Konohana-ku, Osaka-shi, Osaka Inside Hitachi Zosen Corporation (72) Inventor Ken Shiomi 5-chome, Nishikujo, Konohana-ku, Osaka-shi, Osaka No. 3 28 Inside Hitachi Zosen Corporation

Claims (4)

[Claims] 1. A buffer is arranged on an anchor frame in a pier base to expose a surface, a pier body is set on the buffer, and the pier body penetrates the buffer and is connected to an arcer frame. A pier structure for a road bridge, wherein the pier structure is connected and fixed by a fixing member. 2. The pier structure of a road bridge according to claim 1, wherein the buffer is constituted by a buffer laminate in which a steel plate and a synthetic rubber plate are alternately laminated. 3. The pier structure of a road bridge according to claim 1, wherein the buffer is constituted by a buckling structure which buckles at a predetermined pressure. 4. The road bridge according to claim 1, wherein the buffer is replaceably disposed in a storage space formed on the anchor frame of the pier base. Pier structure.