JPH0949209A - Vibration isolation method of bridge and construction of vibration isolation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower vibration energy by erecting the basic section of a damper member of ultra-low yield point steel, etc., on an abutment, etc., connecting the upper part thereof to a girder, and bearing vertical load of the girder on a movable bearing provided on the abutment, etc. SOLUTION: A steel vessel type stopper contraction 23 forming an inward thick flange part forming an opening edge of the upper end as a stopper is embedded into concrete forming an abutment A. A bar-shaped damper member 4 formed of ultra-low yield point steel is vertically erected at a position sharing the center line of the stopper construction 2 is a hollow section thereof while keeping a clearance in a specific size, and a fixed plate 5 of the basic section is fixed with an anchor bolt 6. A bearing pin 8 is inserted into a pin hole 7 formed in a long slot transferring no axial force influenced by thermal deformation on the upper end of the damper member 4 at a right angle to the bridge axis and, at the same time, both ends of the bearing pin 8 is fixed to a girder B borne on the abutment A through a movable bearing 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation method and a seismic isolation structure implemented for damping vibrations of bridge girders during an earthquake and suppressing horizontal displacement of girders from becoming excessive.

[0002]

2. Description of the Related Art In a bridge having a structure of supporting a girder C between an abutment A and a pier B as shown in FIG. 9, as a seismic isolation method or structure of the girder, conventionally, thin iron plates and rubber sheets are alternately used. A well-known laminated rubber laminated and bonded together is used as an isolator (movable bearing) to support the girder so that it can be displaced horizontally, and a lead rod is vertically installed as a damper member at the center of the laminated rubber. Mechanism D is commonly implemented.

[0003]

When a bridge receives an earthquake, seismic waves enter the girder from the pier or abutment and are greatly amplified. For example, it is known that seismic energy of 300 gal at the base of a pier is amplified to 1000 gal when it enters the girder. As a result, horizontal vibrations of heavy girders, especially excessive horizontal displacement, may destroy piers and abutments, resulting in damage such as falling bridges.

The conventional base isolation method or structure using a laminated rubber as an isolator (movable support) and a lead rod incorporated as a damper member has some actions and effects, but a large earthquake occurs. It was difficult to prevent damage such as falling bridges because it lacked the function of suppressing excessive horizontal displacement of the girder when it was received. Therefore, the object of the present invention is to improve the support mechanism to reduce the vibration of the bridge girder at the time of an earthquake, and to prevent the excessive horizontal displacement of the girder at the time of a large earthquake to prevent damage such as bridge collapse. It is to be.

The ultimate object of the present invention is to reduce the vibration energy entering the girder by utilizing the hysteresis damping peculiar to ultra-low yield point steel, etc. It is intended to provide a seismic isolation method and a seismic isolation structure for a bridge that suppresses an excessive displacement when the allowable limit is reached) and also improves damping performance.

[0006]

As a means for solving the above-mentioned problems, the invention of claim 1 is a seismic isolation method between a bridge girder and a bridge pier or abutment supporting the bridge girder, and is characterized by yielding. The base of a rod-shaped damper member made of ultra-low yield point steel with low stress and excellent elongation performance is fixed vertically on a bridge pier or abutment, and the upper part of the damper member transmits only horizontal force and vertical load is transmitted. The structure is not connected to the girder, and the vertical load of the girder is supported by a movable bearing installed on the pier or abutment.

A second aspect of the present invention is also a seismic isolation method between a girder of a bridge and a pier or abutment supporting the girder, which is formed of an ultra-low yield point steel having a low yield stress and an excellent elongation performance. The base of the rod-shaped damper member is fixed to a pier or abutment and stands vertically, and the upper part of the damper member is connected to the girder in a structure that transmits only horizontal force and does not transmit vertical load, and the bending deformation of the damper member is When the size of the damper member is constant, a stopper for contacting and supporting an intermediate portion of the damper member in the vertical direction is provided, and the vertical load of the girder is supported by a movable bearing installed on a pier or abutment.

Next, an invention of claim 3 is a seismic isolation structure between a bridge girder and a bridge pier or abutment supporting the bridge girder, and has an ultra-low yield point steel having a low yield stress and an excellent elongation performance. The rod-shaped damper member formed in 1. is vertically erected with its base fixed to a pier or abutment, and the upper part of the damper member is connected to the girder in a structure that transmits only horizontal force and does not transmit vertical load, Each girder is characterized by being supported on a bridge pier or abutment by a movable bearing that supports its vertical load and does not restrain horizontal movement.

A fourth aspect of the present invention is also a seismic isolation structure between a girder of a bridge and a pier or abutment supporting the girder, which is formed of an ultra low yield point steel having a low yield stress and an excellent elongation performance. The rod-shaped damper member is vertically erected with its base fixed to a bridge pier or abutment, and the upper portion of the damper member is connected to the girder in a structure that transmits only horizontal force but not vertical load. A stopper that supports when the flexural deformation of the damper member reaches a certain amount is fixedly installed at the bridge pier or abutment at an intermediate portion in the vertical direction of the girder. Each is characterized by being supported on a pier or abutment by a movable bearing that does not restrain movement.

The damper member described in claim 1 or 2 or 3 or 4 is made of ultra-low yield point steel, ultra-low yield point steel, lead alloy, pure iron or a material similar thereto. In the connecting structure of the upper part of the damper member and the girder described in claim 3 or 4, the girder or the damper member has a vertically long pin hole which is not affected by a girder load or thermal deformation of the damper member. A support pin that is provided and that transmits only a horizontal force is connected to the pin hole in a horizontal direction.

In the connecting structure between the upper part of the damper member and the girder described in claim 3 or 4, the girder is provided with a long hole in the vertical direction which is not affected by the girder load or thermal deformation of the damper member. The upper part of the damper member is passed through the hole and connected so that only horizontal force can be transmitted. The stopper according to claim 2 or 4 is accommodated in a horizontal structure that surrounds the outer periphery of the intermediate portion of the damper member, or is concentrically arranged with a length that reaches the intermediate portion from the base in the axial direction inside the damper member. It is composed of a rod-shaped structural material.

A horizontal stopper surrounding the outer periphery of the intermediate portion of the damper member is embedded and fixed in concrete forming a bridge pier or abutment.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The seismic isolation method or seismic isolation structure of the present invention comprises a base of a rod-shaped damper member formed of ultra-low yield point steel or the like having a low yield stress and an excellent elongation performance, fixed to a pier or abutment. Vertically, the upper part of the damper member is connected to the girder with a structure that transmits only horizontal force and not vertical load, and the vertical load of the girder is supported by a movable bearing installed on the pier or abutment, or yielding. The base of a rod-shaped damper member made of ultra-low yield point steel with low stress and excellent elongation performance is fixed vertically on a bridge pier or abutment, and the upper part of the damper member transmits only horizontal force and vertical load is transmitted. If the flexural deformation of the damper member reaches a certain level, a stopper is provided to support the vertical middle part of the damper member, and the vertical load of the girder is a movable bearing installed on the pier or abutment. so Are each implemented in the form for lifting. Therefore, the girder supported by the movable bearing on the pier or abutment can be displaced in the horizontal direction.

The damper member, which has its base fixed to a bridge pier or abutment and stands upright, is equivalent to a kind of cantilever. Since the upper part (that is, the free end side) of the damper member is connected to the girder so that only horizontal force can be transmitted, when the girder horizontally displaces due to an earthquake or the like, the horizontal force is transmitted to the damper member to cause bending action. Occurs. At this time, the damper member absorbs and attenuates the seismic energy while performing flexural deformation (elasto-plastic deformation) peculiar to the cantilever beam having the free end subjected to the action of bending load. In this case, the ultra-low yield point steel (extremely low yield point steel) has a low yield point stress of about 1000 Kgf / cm ^{2 as} compared with general steel, as shown in FIG.
Since the elongation performance is 50% or more and the energy absorption performance due to the history is high, the damper member exerts an excellent energy damping effect in the flexural deformation due to the horizontal displacement of the girder.

In the case of the embodiment of the invention described in claim 2 or 4, when the horizontal displacement of the girder reaches a certain magnitude, for example, the horizontal displacement is approached to the limit allowable in the design of the bridge. At the stage, the intermediate portion of the damper member abuts and is supported by the stopper. Therefore, from the stage where the stopper starts to work, as shown by the dotted line in FIG. 3, the damper member receives a bending load at its free end and receives a reaction force at the intermediate position of the stopper. As a result, the cantilever is deformed flexibly, and the horizontal displacement of the girder is suppressed to a small level. However, since the free end side of the damper member still undergoes a corresponding flexural deformation, the energy absorbing function is exerted to its limit. In particular, the bending at this stage exerts a large energy absorbing function peculiar to the statically indeterminate cantilever. Therefore, damage such as falling bridges can be prevented.

As shown in the principle diagram of the seismic isolation method or seismic isolation structure of the present invention in FIG. 1, the pin hole provided in the damper member (or girder) is deformed due to the girder load, or the damper member and girder. Since the length is such that the axial force due to the effect of thermal deformation (thermal expansion or contraction) of (1) is not transmitted, only horizontal force is always transmitted between the girder and the damper member. The support pin is passed through the pin hole in a direction perpendicular to the bridge axis, and mainly contributes to an energy damping action for vibration in the bridge axis direction. Even with respect to vibration in the direction perpendicular to the bridge axis, similarly, a pin connection capable of transmitting only horizontal force can be performed between the damper member and the girder to expect an energy damping action.

[0017]

EXAMPLE A concrete example of the seismic isolation structure implemented based on the principle diagram of FIG. 1 is shown in FIG. The present embodiment relates to a connecting portion between the abutment A (or the abutment B also) and the girder C. First of all, the girder C is supported by a movable bearing 1 on the receiving surface a of the abutment A so that it can be displaced in the horizontal direction under a vertical load. As a concrete structure of the movable support 1, in addition to the above-mentioned known laminated rubber, a support by a steel ball rolling on a steel plate,
Alternatively, a sliding bearing with an oilless plate superimposed is selectively used.

Next, in the concrete forming the abutment A, a steel container-like stopper structure 2 having an open upper end is embedded in a vertical posture and firmly fixed. An inward thick flange portion forming an opening edge at the upper end of the stopper structure 2 is formed as the stopper 3. Incidentally, the embedded height H (see FIG. 3) of the stopper structure 2 is about 4 m. Inside the hollow portion of the stopper structure 2, the center line is shared, and the yield stress is low and the elongation performance is excellent. For example, LYP-100, LYP-2.
Concrete in which a rod-shaped damper member 4 formed of ultra-low yield point steel (or ultra-low yield point steel) such as 35 is erected in a vertical direction, and a fixing plate 5 at the base (lower end) thereof forms the abutment A in advance. It is firmly fixed by a plurality of anchor bolts 6 embedded in it and is configured as a vertical cantilever. Thus, the anchor member 4 is located at the central portion of the horizontal annular stopper 3 and is installed with a predetermined amount of clearance all around. The size of the clearance is set to a position where the stopper 3 works by suppressing the horizontal displacement of the girder from becoming excessive. Therefore, the relationship between the stopper 3 and the damper member 4 is roughly classified into a case where the clearance S is provided only in the bridge axial direction as shown in FIG. 5A and a case where the clearance S is provided uniformly over the entire circumference as shown in FIG. 5B. It FIG. 5C shows an embodiment in which the damper member 3 has a circular cross section. The damper member 4 has a round bar or square bar shape with a diameter of about 40 cm and a length of about 6 m. In addition to the above-mentioned ultra-low yield point steel, one similar to so-called pure iron, and similarly low yield stress and excellent elongation performance. It is made of a lead alloy that exhibits excellent properties or a material similar thereto. The base fixing plate 5 is made of a general steel material such as SS41.
The fixing plate 5 is fixed by a hole-in anchor, by means of welding to the bottom of the stopper structure 2 or the like, in addition to the anchor bolt 6. The upper end opening of the stopper structure 2 is sealed with a cover 9 made of flexible rubber, plastic or the like to prevent dust and rainwater from entering (FIG. 3).

A pin hole 7 is formed at the upper end of the damper member 4 in the vertical direction. The pin hole 7 is a long hole that does not transmit axial force due to the influence of girder load or thermal deformation of the damper member. Both ends of a support pin 8 which is horizontally passed through the pin hole 7 in the direction perpendicular to the bridge axis are fixed to the girder C, so that the upper part of the damper member 4 and the girder C and the horizontal force (in particular, the horizontal force in the bridge axis direction). It is connected by a structure that transmits only the vertical load and not the vertical load. The width of the pin hole 7 is substantially equal to the outer diameter of the support pin 8, and there is no play in the bridge axis direction. The horizontal force in the direction perpendicular to the bridge axis is transmitted by the girder C directly contacting the damper member 4, but if necessary, another pin passing through the damper member 4 in the bridge axis direction may be provided. A structure in which a hole is provided and a horizontal force in the direction orthogonal to the bridge axis is also transmitted by the support pin through the support pin in the bridge axis direction can be implemented. Although the support pin 8 is expected to have a function of preventing the girder C from jumping, if this function is neglected, the steel frame material constituting the girder is provided with a hole having a length that is not affected by the girder load or thermal deformation of the damper member. Is vertically extended, and the base is fixed to a pier or abutment.The upper part of a vertical rod-shaped damper member is simply passed through the hole, and only horizontal force can be transmitted without using a support pin. You can also do it.

Next, in FIG. 6, the vertical damper member 4 is passed through the vertical hole of the girder C, and the retaining pin 10 or the trapezoidal block 11 is provided at the upper end thereof, and the stopper structure is provided on the abutment B. The example which fixedly provided the thing 2 is shown.
In the case of the present embodiment, when the girder C is horizontally displaced and the flexural deformation of the damper member 4 becomes a certain amount, the stopper 3 abuts on the intermediate portion of the damper member to work, so that the girder C is displaced in the horizontal direction. Prevent it from becoming too large.

FIG. 7 shows a stopper structure 2 in which the base of the damper member 4 is fixed vertically on a bracket 12 provided on the side of the pier B (or abutment A) and fixed on the same bracket 12. Damper member 4 by stopper 3
An example is shown in which an intermediate portion of the above is supported to suppress an excessive horizontal displacement. Next, in FIG. 8, the rod-shaped stopper 12 is
Axial along the center line of the rod-shaped damper member 4,
It shows an embodiment in which it is fitted and embedded in a length reaching from the base portion to the intermediate portion. The relationship between the stopper 12 and the damper member 4 in this embodiment is equal to the relationship between the stopper and the damper member shown in FIGS.

[0022]

[Effects of the Present Invention] The seismic isolation method and structure of a bridge according to the present invention have the following effects. For small and medium-sized earthquakes, seismic energy is reduced and horizontal forces are dispersed by lengthening the horizontal vibration of the girder and high damping action (seismic isolation function). In the event of a large earthquake, the stopper acts to prevent excessive horizontal displacement of the girder, and at the same time improves the seismic energy absorption capacity (function as a damper stopper). The seismic isolation structure is simple, and maintenance is easy unless there is a significant residual displacement due to a large earthquake. Especially suitable for seismic isolation of bridges with high girders such as long bridges. Since the stopper shape and the cross-section of the damper member have a high degree of freedom, a seismic isolation structure (damper structure) can be designed according to needs.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating the principle of a seismic isolation method or a seismic isolation structure of the present invention.

FIG. 2 is a cross-sectional view showing a first embodiment of the seismic isolation structure of the present invention.

FIG. 3 is a cross-sectional view showing the functions of a stopper structure and a stopper.

FIG. 4 is a stress-strain characteristic diagram of ultra low yield point steel.

5A to 5C are horizontal sectional views showing the relationship between the stopper and the damper member.

FIG. 6 is a sectional view showing a second embodiment of the seismic isolation structure of the present invention.

FIG. 7 is a sectional view showing a third embodiment of the seismic isolation structure of the present invention.

FIG. 8 is an elevational view showing an example of a configuration in which a damper member and a stopper are different.

FIG. 9 is a structural explanatory view of a bridge in general.

[Explanation of symbols]

 A Abutment B Bridge pier C Girder 4 Damper member 1 Movable bearing 3 Stopper 7 Pin hole 8 pin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisetsu Otsuka 1 Asahi, Asahi, Tsukuba, Ibaraki Prefectural civil engineering research institute (72) Inventor Shigeki Unjo, 1 Asahi, Tsukuba, Ibaraki Prefectural civil engineering research institute ( 72) Inventor Hideki Mukai, Asahi 1 Tsukuba, Ibaraki Prefecture, Asahi, Civil Engineering Research Institute, Ministry of Construction (72) Inventor Michio Sugimoto 8-21-1, Ginza, Chuo-ku, Tokyo Stockholder, Takenaka Civil Engineering (72) Inventor, Takashi Hirai Takenaka Civil Engineering Co., Ltd., 8-21-21 Ginza, Chuo-ku, Tokyo (72) Inventor Kazuhiko Suzuki Inventor Takenaka Civil Engineering Co., Ltd. 8-2-1-21, Ginza, Chuo-ku, Tokyo (72) Morio Seisei Tokyo 2-6-3 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corporation

Claims (10)

[Claims] 1. A seismic isolation method between a bridge girder and a pier or abutment supporting the bridge girder, comprising a rod-shaped damper member made of ultra-low yield point steel or the like having low yield stress and excellent elongation performance. The base is fixed to the pier or abutment and stands vertically, and the upper part of the damper member is connected to the girder with a structure that transmits only horizontal force but not vertical load. The vertical load of the girder is movable on the pier or abutment. A seismic isolation method for bridges, characterized in that they are supported by bearings. 2. A seismic isolation method between a bridge girder and a bridge pier or abutment supporting the bridge girder, comprising a rod-shaped damper member formed of ultra-low yield point steel or the like having low yield stress and excellent elongation performance. The base is fixed to a bridge pier or abutment and is erected vertically, and the upper part of the damper member is connected to the girder in a structure that transmits only horizontal force and not vertical load. When the flexural deformation of the damper member becomes constant, A method for seismic isolation of a bridge, characterized in that a stopper for supporting an intermediate portion in the vertical direction of the damper member is provided, and that the vertical load of the girder is supported by a movable bearing installed on a pier or abutment. 3. A seismic isolation structure between a bridge girder and a bridge pier or abutment supporting the bridge girder, wherein a bar-shaped damper member formed of ultra-low yield point steel or the like having low yield stress and excellent elongation performance is provided. The base is fixed vertically to a bridge pier or abutment and is erected vertically, and the upper part of the damper member is connected to the girder in a structure that transmits only horizontal force and not vertical load, and the girder supports the vertical load. Being supported on a pier or abutment by a movable bearing that does not restrain horizontal movement,
A seismic isolation structure for the bridge, featuring 4. A seismic isolation structure between a bridge girder and a bridge pier or abutment supporting the bridge girder, wherein a bar-shaped damper member made of ultra-low yield point steel or the like having low yield stress and excellent elongation performance is provided. The base is fixed vertically to a bridge pier or abutment and is erected vertically, and the upper part of the damper member is connected to the girder in a structure that transmits only horizontal force and not vertical load. In addition, a stopper that supports when the flexural deformation of the damper member becomes a certain amount is fixedly installed on the pier or abutment, and the girder supports the vertical load and does not restrain the horizontal movement of the movable support. Supported on the pier or abutment with
A seismic isolation structure for the bridge, featuring 5. The damper member according to claim 1 or 2 is formed of ultra-low yield point steel, ultra-low yield point steel, lead alloy, pure iron, or a material similar thereto. The characteristic method of seismic isolation of bridges. 6. The damper member according to claim 3 or 4 is formed of ultra-low yield point steel, ultra-low yield point steel, lead alloy, pure iron, or a material similar thereto. The characteristic is the seismic isolation structure of the bridge. 7. The connection structure between the upper portion of the damper member and the girder according to claim 3 or 4, wherein the girder or the damper member has a pin hole having a length that is not affected by the girder load or thermal deformation of the damper member. A seismic isolation structure for a bridge, characterized in that it is vertically long and is connected to a support pin that transmits only a horizontal force through the pin hole in the horizontal direction. 8. The connection structure of the upper part of the damper member and the girder described in claim 3 or 4, wherein the girder has a hole having a length long in the vertical direction which is not affected by a girder load or thermal deformation of the damper member. A seismic isolation structure for a bridge, characterized in that an upper part of a damper member is provided through the hole and connected so that only a horizontal force can be transmitted. 9. The stopper according to claim 2 or 4,
It is composed of a horizontal structural member that surrounds the outer periphery of the intermediate portion of the damper member, or a rod-shaped structural member that is housed in a concentric arrangement with a length that reaches the intermediate portion from the base in the axial direction inside the damper member. The characteristic is the seismic isolation structure of the bridge. 10. The bridge according to claim 9, wherein the horizontal stopper surrounding the outer periphery of the intermediate portion of the damper member is embedded and fixed in concrete forming a bridge pier or abutment. Seismic isolation structure.