JP3153774B2 - Seismic isolation bearing for bridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a seismic isolation bearing for a building or the like, and more particularly to a seismic isolation bearing mounted on a relatively small surface such as a pier and supporting a superstructure such as a bridge body. In particular, the present invention relates to a seismic isolation bearing for a bridge composed of an upper shoe and a lower shoe, which are in contact with each other and transmit a bridge superstructure load to a pier.

[0002]

2. Description of the Related Art When constructing a bridge, a bearing is placed between the pier upper surface and the bridge superstructure to transmit the load of the superstructure to the pier. The entire bridge is severely damaged by the natural disaster. Therefore, in recent years, many proposals have been made regarding technology for protecting a building from an earthquake by using a bearing as a seismic isolation bearing.

[0003] The most typical one is to use a laminated rubber for all or a part of a bearing structure, but there is a problem of locking, which is not suitable as a seismic isolation bearing for a bridge. On the other hand, Japanese Patent Publication No. 4-65193 discloses a technique in which the position of a bridge superstructure once moved by an earthquake is restored by gravity. However, when using this technology, since the pull-out prevention device for preventing the structure from falling due to the vertical movement of the earthquake is independently provided outside the seismic isolation bearing main body, the support that has only a relatively small area like a pier It is unsuitable for mounting on a surface to support a superstructure.

In a bridge, when a large displacement of a superstructure occurs due to an earthquake, another superstructure adjacent to the bridge,
Since a collision with the abutment occurs, it is necessary to suppress the displacement during the earthquake so as not to be too large and to attenuate the shaking as early as possible. Furthermore, unlike seismic isolation bearings that are placed on the foundations of buildings, seismic isolation bearings placed on piers are directly exposed to wind and rain, and dust easily enters the bearings. is there. However, no specific proposal has been made for these.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a seismic isolation bearing suitable for being installed on a pier of a bridge, and to solve the above-mentioned problems of the conventional seismic isolation bearing. In other words, the seismic isolation bearing is reduced in size (compacted), works effectively on a small area on the pier, and has good workability (handlability), and suppresses excessive displacement of the bridge superstructure. And also the early absorption of seismic energy,
It enables attenuation. Further, the present invention proposes a specific mechanism for protecting the bearing from wind, rain, and dust.

[0006]

In order to solve the above problems, the present invention employs the following means. First of all, the seismic isolation bearing for bridges consists of an upper shoe and a lower shoe, which are in contact with each other via the contact surface, and transmit the upper work load of the bridge to the pier. A convex surface on one side, a concave surface on the other side, and slidable with each other, penetrating a contact area between the upper and lower shoes, disposing a pin for fixing an upper work and an insertion hole thereof, and In the periphery of the lower shoe,
This is a seismic isolation bearing for bridges that has a mechanism to prevent the upper and lower shoes from being pulled out, enabling the seismic isolation bearing to be made smaller (compact, integrated).

In the above-described seismic isolation bearing, the pull-out preventing mechanism comprises a surrounding wire, a bolt directly connected to the wire, and a nut for fixing the bolt to upper and lower shoes.
In addition, one end of the bolt is fixed to one of the upper and lower shoes via a spring. Further, the present invention has a configuration in which a seal member is disposed between the upper and lower shoes to protect the bearing from wind, rain, and dust. Further, the present invention surrounds the upper shoe and the lower shoe, and arranges an energy absorbing member between the bridge superstructure and the pier upper surface, thereby suppressing excessive displacement of the bridge superstructure and early absorbing seismic energy. It is assumed. Specifically, as the material,
Mild steel with low yield point and large elongation is used.

As shown in FIG. 1, the basic structure of the seismic isolation bearing 1 of the present invention comprises an upper shoe 2 and a lower shoe 3, one of which is concave, the other is convex, and these are brought into contact with each other. It has a structure that slides with each other in the event of an earthquake. As shown in FIG. 2, this seismic isolation bearing 1 is installed between the pier F and the superstructure U, and has a function of blocking seismic energy from the superstructure. Specifically, the upper shoe 2 is made to have a concave surface, while the lower shoe 3 is made to have a convex surface having a slightly smaller radius of curvature than the upper shoe 2, and these are brought into surface contact by the load of the bridge superstructure U. Thus, the load of the superstructure U is transmitted to the pier F. The curvature of the contact surface between the upper shoe 2 and the lower shoe 3 is determined in consideration of the ease of sliding of both, the reaction force at the contact surface, and the like.

The upper shoe 2 and the lower shoe 3 are integrally formed of a steel material having sufficient strength as in the case of a normal bearing, but their contact surfaces are not restricted in their directions by seismic energy. , Can be finished to slide. For bridges,
Since it is only necessary to consider seismic isolation and restoration in the event of a large earthquake, even if the frictional resistance is somewhat large, it is sufficient if the rustproofing treatment is applied. In this example, the upper shoe 2 is concave, and the lower shoe 3
Has a convex surface, but the reverse configuration is also possible. Considering the ease of mutual sliding, the convex side is preferably slightly wider than the mutual contact surface due to the bridge load, as shown in the figure, and the convex surface exists corresponding to the entire concave side. You don't have to. In short, it suffices if it is configured such that mutual sliding is possible and the engagement state of the upper and lower shoes is not easily disengaged.

An upper work fixing pin 4 and an insertion hole 5 for the pin are arranged through a contact portion between the upper shoe 2 and the lower shoe 3. The pin 4 attaches the superstructure U to the pier F so that the bridge superstructure U does not move in a normal state, that is, a force applied by wind or a vehicle, or a force applied by a slight earthquake. In the event of a large earthquake, for example, an earthquake with a seismic intensity of more than 5, it is broken by the force received from the bridge superstructure U, and the fixing and connection between the superstructure U and the pier F are released. Work U to Pier F
It is possible to move freely with respect to. Therefore,
The thickness of the pin 4 may be determined in consideration of the seismic acceleration and the mass of the superstructure U supported by the pin 2 so as to achieve the above function. The pin insertion hole 5 is for replacing a pin broken by an earthquake with a new pin.
When there is no earthquake disaster for a long time, check the pins,
It allows for exchange. This insertion hole may penetrate the upper shoe and extend to the pin insertion depth of the lower shoe as shown in FIG. 1, and the diameter may be substantially the same as the diameter of the pin.

In the present invention, a mechanism 6 for preventing the upper and lower shoes from being pulled out is provided around the upper and lower shoes 2 so as to penetrate the upper and lower shoes 2. The pull-out prevention mechanism 6 prevents the upper shoe 2 from jumping up and falling together with the superstructure U due to the earthquake vertical movement, and prevents the lower shoe 3 and the pier F from being damaged. Specifically, the pull-out prevention mechanism 6
As shown in detail in FIG. 1 and FIG. 3 as part A, the upper and lower shoes are connected by a flexible wire 7 and a spring 8 is provided at a support point. The pull-out resistance is adjusted by tightening. Further, the wire is provided through a hole 11 penetrating the upper and lower shoe, and a certain clearance 12 is provided between the hole 11 and the wire 7 to form a so-called floating hole. This not only achieves the purpose of preventing the pull-out, but also facilitates mutual sliding of the upper and lower shoes during an earthquake due to the synergistic action of the spring and the clearance. The pull-out prevention mechanism 6
Are provided in the periphery of the upper and lower shoe, but are accommodated in the seismic isolation bearing, so that the seismic isolation bearing is extremely compact as a whole.

FIG. 4 shows a state where the wire 7 is attached to the lower shoe of FIG. As shown here, a bolt 13 is directly connected to one end of the wire 7, and is fixed to the outer periphery of the lower shoe via a nut 14.

In the seismic isolation bearing of the present invention, the contact area between the upper and lower shoes is protected from corrosion by wind and rain and the like, and dust is prevented from entering from the outside. A seal is applied. By doing so, the slidability between the upper shoe 2 and the lower shoe 3 is maintained for a long time.
Specifically, as shown in FIG. 1, a sealing member 15 such as a laminated rubber is disposed around the upper and lower shoe. In addition,
If the sealing means is made of laminated rubber, the mutual movement of the upper shoe 2 and the lower shoe 3 at the time of an earthquake is buffered by the laminated rubber as the sealing means, and there is also an effect of damping vibration. However, the sealing means is not limited to the laminated rubber as in the above example,
A softer synthetic resin such as polyurethane or an O-ring made of rubber may be used.

In the present invention, it is preferable that an energy absorbing member is disposed between the upper bridge and the upper surface of the pier, surrounding the upper and lower shoes. Thereby, when the upper shoe 2 and the lower shoe 3 make a large relative movement due to the earthquake, the range is suppressed within the inner diameter of the energy absorbing member and its deformation range, and the kinetic energy due to the acceleration due to the earthquake is absorbed by the energy. Absorption is alleviated by deformation of the member. Therefore, after the seismic wave stops, the swing of the superstructure can be led to the stop early.

The energy absorbing member 16 may be a cylindrical member surrounding the upper and lower shoe, and its size is such that its inner diameter is the sum of the outer diameter of the upper and lower shoe and the allowable amount of relative movement of the upper and lower shoe. Good. The installation need only surround the upper and lower shoes (2, 3), and does not need to be fixed to the superstructure U or the pier F. However, if disposed between the superstructure U and the pier F in a pressed state, the contact surfaces of the upper and lower shoe can be protected in combination with the above-described sealing member or by replacing the function of the sealing member.

[0016] The energy absorbing member may be a member capable of absorbing kinetic energy of a bridge structure due to an earthquake.
Any material may be used, but it is particularly preferable to use extremely mild steel. Extremely mild steel has a low yield point and a large elongation before breaking, and when shocking external energy is applied, it absorbs the energy by deformation.

[0017]

EXAMPLE A dynamic response analysis model shown in FIG. 5 was prepared by using the bearing according to the present invention as an inelastic spring system, whereby the seismic wave of the Hyogoken Nanbu Earthquake (Kobe Ocean Meteorological Observatory record: NS component) was used. A simulation experiment was performed. As a result, when the seismic isolation device was not provided, the displacement of the upper end of the bridge having a height of 2.5 m was 34.1 cm. However, when the present invention and the seismic isolation device were provided, the displacement was greatly reduced to 10.6 cm. It became clear.

[0018]

Since the present invention has the above-mentioned structure, it is possible to provide an integrated and compact seismic isolation bearing for a bridge, and to use the bridge to easily perform disaster prevention of the bridge. . Further, as described above, the present invention has a mechanism for preventing corrosion from outside air and a dustproof mechanism, so that maintenance is easy and it can withstand long-term use.

[Brief description of the drawings]

FIG. 1 is a sectional view of a seismic isolation bearing according to the present invention.

FIG. 2 is a sectional view showing an installed state of the seismic isolation bearing of the present invention.

FIG. 3 is a schematic enlarged view showing a state in which the pullout prevention mechanism is attached to an upper shoe.

FIG. 4 is a schematic enlarged view showing a state in which the pullout prevention mechanism is attached to a lower shoe.

FIG. 5 is a conceptual diagram of a dynamic response analysis model used for confirming the effect of the present invention.

[Explanation of symbols]

 1: seismic isolation bearing 2: upper shoe 3: lower shoe 4: superstructure fixing pin 5: superstructure fixing pin insertion hole 6: pull-out prevention mechanism 7: wire 8: spring 9: nut 10: bolt 11: upper and lower shoe penetration Hole 12: Clearance 13: Bolt 14: Nut F: Bridge pier U: Bridge superstructure

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Hiramoto 2-3-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo Kawasaki Steel Corporation (58) Field surveyed (Int. Cl. ⁷ , DB name) E01D 19 / 04 E01D 19/04 101

Claims (6)

(57) [Claims] 1. A seismic isolation bearing for a bridge, comprising an upper shoe and a lower shoe, which are in contact with each other via a contact surface and transmit a bridge superstructure load to a pier. With a concave surface and configured to be slidable with each other, a pin for fixing a superstructure and an insertion hole for the pin are provided through the contact area between the upper and lower shoes, and around the upper and lower shoes, A seismic isolation bearing for bridges that has a pull-out prevention mechanism between the upper and lower shoes. 2. The pull-out prevention mechanism comprises a surrounding wire, a bolt directly connected to the wire, and a nut for fixing the bolt to upper and lower shoes, and one end of the bolt is fixed to the shoe via a spring. The seismic isolation bearing for a bridge according to claim 1, wherein the support is provided. 3. The seismic isolation bearing for a bridge according to claim 1, wherein a seal member is disposed between the upper shoe and the lower shoe. 4. The seismic isolation bearing according to claim 3, wherein the seal member is made of a member having an energy absorbing ability. 5. The bridge according to claim 1, further comprising an energy absorbing member which surrounds the upper and lower shoes and is disposed between the bridge superstructure and the pier upper surface. For seismic isolation bearings. 6. The seismic isolation bearing for a bridge according to claim 5, wherein the shock absorbing member is made of extremely mild steel.