JPH10110777A - Base isolating device for bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a critical friction resistance value generated on sliding surface from an upper base isolating material and a lower base isolating material by forming the upper base isolating material out of steel material involving a protrusion at the sliding surface, and forming the lower base isolating material out of elastic material with a smooth sliding surface. SOLUTION: An upper base isolating material 12 is fitted on a supporting plate 3d of a bearing plate 3b, and a lower base isolating material 13 is fitted on the top face of a bridge pier 2. The upper vibration isolating material of a vibration isolating device 10 is made of steel material, for example, stainless steel, on whose sliding surface one or a plurality of protrusions 12a are formed. On the other hand, the lower base isolating material 13 is formed with flexible polymeric material for a smooth sliding surface. An excessive relative sliding amount between the upper and lower base isolating materials 12, 13 generated when earthquake force acts is regulated, and stoppers 14, 15 are disposed for prevention of lifting of the base isolating device 10. A spring 16 is fitted between the base isolating device 10 and the stoppers 14, 15 so as to resist horizontal force in a bridge axis direction for promoting damping and base isolating actions of the base isolating device 10 and in an orthogonal direction to the bridge axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a seismic isolation device for a bridge.

[0002]

2. Description of the Related Art The importance of seismic structures for bridges has been reconfirmed in the wake of the Great Hanshin-Awaji Earthquake, and the present invention also relates to the seismic structures for bridges. It is. FIGS. 7 and 8 show a main structure of a general bridge, and show a structure in which a bridge girder is supported by a pier 2 via a plurality of (two sets in the figure) bearings 3 and 4. FIG. The conventional support structure is composed of an upper support plate 3a as shown in FIGS.
And the lower support plate 3b are connected by a support pin 3c, and the upper support plate 4a and the lower support plate 4b are connected by a support pin 4c. In the bearing 4 shown in the figure, a roller 17 is interposed between the lower bearing plate 4b and the pier 2, and allows the bridge girder 1 to be displaced in the bridge axial direction caused by a temperature change or the like. 8A is a view taken in the direction of arrow A in FIG. 7, and FIG.
An arrow is shown.

[0003] As described above, the conventional bridge support structure is the bridge girder 1.
However, the seismic vibration is transmitted directly through the left bearing 3, which may be amplified and cause serious damage to each part of the bridge. Was.

The present invention provides a seismic isolation device for a bridge in which the above-mentioned problems are solved and seismic isolation measures are taken.

[0005]

The present invention has the following matters specifying the invention. (1) In a bridge in which a bridge girder is pointed by a pier via a bearing, a pair of upper seismic isolation material and lower seismic isolation that can relatively slide in the bridge axis direction and in the direction perpendicular to the bridge axis between the bearing and the pier. The upper seismic isolation material is formed of a steel material having a projection on a sliding surface, and the lower seismic isolation material is formed of an elastic material having a smooth sliding surface. It is characterized by the following. (2) A critical friction resistance value generated on the sliding surface is determined by the upper and lower seismic isolation materials. (3) A spring is mounted to resist the horizontal force acting on the seismic isolation material. (4) The above-mentioned seismic isolation material is provided with a stopper for regulating a relative slip amount between the upper and lower seismic isolation materials. (5) The above-mentioned seismic isolation material is provided with a stopper for preventing the seismic isolation material from floating.

The protrusion of the upper seismic isolation member is pushed into the smooth sliding surface of the lower seismic isolation member due to the weight of the bridge girder added to the bearing. In this state, horizontal force in the direction of the bridge axis or in the direction perpendicular to the bridge axis is generated. When actuated, the protrusions of the upper seismic isolation material slide relative to each other while pushing out the depression of the smooth sliding surface of the lower seismic isolation material, and the horizontal force is supported by the frictional resistance generated at that time, and the energy is attenuated. In this case, the frictional resistance generated on the sliding surface of the upper and lower seismic isolation materials increases and decreases in proportion to the horizontal force, but is determined by the size and shape of the projections of the upper seismic isolation material, the material of the lower seismic isolation material, etc. The horizontal force exceeding the limit frictional resistance of the sliding surface is not transmitted via the bearing. Therefore, the critical friction resistance is determined according to the seismic performance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an embodiment of the present invention will be described with reference to FIGS. The same parts as those in FIGS. 7 and 8 are denoted by the same reference numerals. FIG. 1 is a diagram corresponding to FIG. 7 and shows the installation status of the seismic isolation device. In FIG. 1, in a bridge in which a bridge girder 1 is supported by a pier 2 via a left bearing 3 and a right bearing 4, a seismic isolation device 10 is interposed and grounded between the left and right bearings 3, 4 and the pier 2. It is. In this case, as shown in FIG. 8, each bearing 3, 4 is installed, for example, one set in the bridge width direction, and the seismic isolation device is installed in each bearing 3, 4.

FIGS. 2 and 3 show a case where the seismic isolation device 10 is installed on the left bearing 3 side. The left bearing 3 includes an upper bearing plate 3a attached to the bridge girder 1 and a lower bearing plate 3b on the pier 2 side. Are connected by support pins 3c, and a seismic isolation device 10 is interposed / installed between the receiving plate 3d of the lower support plate 3b and the upper surface of the pier 2. The seismic isolation device 10 includes a pair of upper and lower seismic isolation members 1 that are in contact with each other so as to be relatively slidable in a bridge axis direction and a direction perpendicular to the bridge axis.
The upper seismic isolation member 12 is attached to the receiving plate 3d of the lower support plate 3b, and the lower seismic isolation plate 13 is attached to the upper surface of the pier 2. The upper seismic isolation member 12 of the seismic isolation device 10 is made of a steel material, for example, stainless steel, and one or a plurality of projections 12a, for example, conical or spherical projections are formed on a sliding surface thereof, and the other lower part is formed. The seismic isolation member 13 is formed of a flexible polymer material, for example, a polyfluoroethylene resin, and the sliding surface is formed smoothly. Further, the seismic isolation device 10 is provided with a stopper 14 for controlling an excessive relative slip between the upper and lower seismic isolation members 12 and 13 when seismic force is applied, and for preventing the seismic isolation device 10 from floating. And 15 are installed, and the seismic isolation device 1
A spring 16 is mounted between the zero and the stoppers 14 and 15 to resist horizontal force in the bridge axis direction and in the direction perpendicular to the bridge axis so as to promote damping and seismic isolation of the seismic isolation device 10.

FIGS. 4 and 5 similarly show a case where the seismic isolation device 10 is installed on the right support 4 side. In this case, the upper support plate 4a attached to the bridge girder 1 and the lower support plate 4b on the pier 2 side are connected. The roller 17 is connected between the support plate 4d of the lower bearing plate 4b and the pier 2, and the seismic isolation device 10 is installed between the roller 17 and the pier 2. You. That is, the difference between FIGS. 2 and 3 and FIGS. 4 and 5 is that the roller 17 is interposed between the receiving plate 4 d and the upper seismic isolation member 12 of the seismic isolation device 10.

The operation of the seismic isolation device will be described below. The bridge girder weight is always applied to the seismic isolation device 10 via the bearings 3 and 4, so that the protrusion 12 a of the upper seismic isolation member 12 is pushed into the smooth sliding surface of the lower seismic isolation member 13. It is in. In this state, the axial elongation of the bridge girder 1 caused by a temperature change or the like is absorbed by the action of the rollers 17 provided on the right support 4. On the other hand, the horizontal force generated in the bridge axis direction and the direction perpendicular to the bridge axis caused by the earthquake is transmitted in the two directions in the left bearing 3, but in the right bearing 4 due to the action of the roller 17 in the bridge axis direction. Is absorbed and only the horizontal force in the direction perpendicular to the bridge axis is transmitted. FIG. 6 shows the state of the sliding surface of the seismic isolation device 10 when a horizontal force is applied, and the projection 12a of the upper seismic isolation material 12 pushed into the smooth sliding surface of the lower seismic isolation material 13 smoothly slides. Surface dent 13
Both slide relatively to each other while spreading a, and the horizontal force is supported by the frictional resistance generated at this time, and the seismic energy is attenuated. At this time, the volume (a) of the depression 13a of the lower seismic isolation member 13 expanded by the projection 12a increases and decreases in proportion to the applied horizontal force, and therefore, the frictional resistance (that is, apparent friction coefficient) generated on the sliding surface. Increases and decreases in proportion to the horizontal force, and can exhibit a damping action corresponding to an arbitrary horizontal force. The limit frictional resistance (apparent maximum coefficient of friction) that can be generated on the sliding surface is determined by the size and shape of the protrusion 12a of the upper seismic isolation member, the material and properties of the lower seismic isolation member 13, and more. Since the horizontal force cannot be transmitted through the bearings 3 and 4, this seismic isolation prevents the catastrophic damage to the bridge.

[0011]

As described above, according to the bridge seismic isolation device of the present invention, the lower seismic isolator made of a flexible elastic material has a smoother protrusion on the upper seismic isolator sliding surface made of a steel material. Since the bridge girder weight is supported while being pushed into the sliding surface, when a horizontal force acts, the protrusions slide relatively to each other while pushing out the depressions on the smooth sliding surface, and any frictional resistance generated at that time causes Horizontal force can be effectively absorbed and attenuated. In addition, since the limit frictional resistance that can be generated on the sliding surface is determined by the size and shape of the projection of the upper seismic isolation material, the material of the lower seismic isolation material, etc., by setting these appropriately, the excessive horizontal force can be reduced. It is not transmitted via bearings, which has the effect of preventing fatal damage to the bridge.

[Brief description of the drawings]

FIG. 1 is a schematic view according to an example of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a left bearing portion along a bridge axis direction.

FIG. 3 is a configuration diagram of a left bearing portion along a direction perpendicular to a bridge axis.

FIG. 4 is a configuration diagram of a right bearing portion along a bridge axis direction.

FIG. 5 is a configuration diagram of a right bearing portion along a direction perpendicular to a bridge axis.

FIG. 6 is an explanatory view showing deformation of the seismic isolation material due to sliding.

FIG. 7 is a schematic diagram of a conventional example.

FIG. 8 is a view as viewed from AA and BB in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bridge girder 2 Bridge pier 3, 4 Bearing 3a, 4a Upper bearing plate 3b, 4b Lower bearing plate 3c, 4c Support pin 3d, 4d Receiving plate 10 Seismic isolation device 12 Upper seismic isolation material 12a Projection 13 Lower seismic isolation material 13a Indentation 14, 15 Stopper 16 Spring 17 Roller

Claims (5)

[Claims] 1. A bridge in which a bridge girder is designated by a pier via a bearing, wherein a pair of upper seismic isolation members and a lower member which can relatively slide in a bridge axis direction and a direction perpendicular to the bridge axis between the bearing and the pier. The upper seismic isolation material is made of a steel material with a projection on the sliding surface, and the lower seismic isolation material is made of an elastic material with a smooth sliding surface. A seismic isolation device for a bridge, characterized in that: 2. The seismic isolation device for a bridge according to claim 1, wherein a critical friction resistance value generated on a sliding surface is determined by the upper seismic isolation material and the lower seismic isolation material. 3. The seismic isolation device for a bridge according to claim 1, wherein a spring is mounted to resist horizontal force acting on the seismic isolation material. 4. The seismic isolation device for a bridge according to claim 1, wherein the seismic isolation member is provided with a stopper for regulating a relative slip amount between the upper and lower seismic isolation members. 5. The seismic isolation device for a bridge according to claim 1, wherein the seismic isolation material is provided with a stopper for preventing the seismic isolation material from rising.