JP2555833B2 - Seismic isolation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated rubber seismic isolation device which enables a structure to have a long period.

[0002]

A seismic isolation device for a laminated rubber bearing has a structure in which laminated rubber formed by laminating rubber and steel plates is sandwiched between upper and lower flanges fixed to an upper structure and a lower structure. While its vertical load bearing capacity and rigidity are high, its horizontal rigidity is low, and it has the characteristic of extending the vibration cycle of the supporting structure and restoring it while supporting the structure as a spring. Since the laminated rubber has a solid cross-sectional shape because it needs to support the vertical load of the structure, the cycle of the laminated rubber bearing itself based on the horizontal rigidity determined by the size of the cross-sectional area is limited to about 1 to 2 seconds at most. Has become.

The present invention was made by paying attention to the limit of the long period of the conventional laminated rubber bearing, and is intended to newly propose a seismic isolation device for the laminated rubber bearing which enables a longer period. is there.

[0004]

[Means for Solving the Problems] The horizontal rigidity that determines the cycle of laminated rubber bearings decreases as the cross-sectional area decreases, and the stability increases when a vertical load is applied as the diameter increases for the same cross-sectional area. Therefore, in order to secure the stability and to prolong the cycle, it is advantageous to make the cross-sectional shape of the support hollow and to increase the distance from the center to the outer circumference, that is, the outer diameter in the case of a circle, If the outer diameter is increased to improve stability under the condition of a constant cross-sectional area, the laminated rubber becomes thinner and buckles more easily, so this buckling problem can be solved in order to realize a long period. Indispensable.

In the present invention, the basic shape of the laminated rubber bearing is formed to have a hollow cross-sectional shape, and at the same time, the horizontal area of the bearing is reduced to reduce the horizontal rigidity of the bearing to prolong the cycle, while only the horizontal load is applied to the basic shape. In this way, the vertical load is not applied to improve stability and solve the problem of buckling due to thinning.

The main body of the seismic isolation device is composed of a peripheral laminated rubber having a hollow cross-sectional shape and a central laminated rubber arranged in the central portion on the transverse cross section of the peripheral laminated rubber. The central laminated rubber has an upper structure. By exerting the vertical load of the object, the action of compressive force on the peripheral type laminated rubber of the basic type is avoided, and the reduction of the horizontal rigidity and the stability of the laminated rubber bearing can be achieved at the same time. Overcoming the weaknesses associated with reduced cross-sectional area and thinning.

As a result, it is possible to increase the distance from the center to the outer circumference, that is, the ratio of the distance from the outer circumference to the outer circumference, while reducing the cross-sectional area of the peripheral laminated rubber. It is possible to reduce the horizontal rigidity of the seismic device.

Loading the vertical load only on the central laminated rubber is realized by previously introducing a tensile force in the axial direction of the peripheral laminated rubber.

The horizontal rigidity of the seismic isolation device is determined by the total cross-sectional area of the peripheral laminated rubber and the central laminated rubber, but by making the cross-sectional area of the central laminated rubber relatively smaller than that of the peripheral laminated rubber, The horizontal rigidity of the peripheral laminated rubber becomes dominant, and the horizontal rigidity of the peripheral laminated rubber determines the horizontal rigidity of the seismic isolation device.

Since the period of the seismic isolation device is determined by the horizontal rigidity of the peripheral laminated rubber, and the cross-sectional area of the peripheral laminated rubber can be reduced, the sectional area of the peripheral laminated rubber can be reduced and at the same time, By increasing the distance to the outer circumference, the seismic isolation device can be made longer while stably supporting the upper structure.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing an embodiment.

As shown in FIGS. 1 and 2, the seismic isolation device 1 of the present invention includes an upper flange 2 and a lower flange 3 fixed to an upper structure S ₁ and a lower structure S ₂ , respectively, an upper flange 2 and a lower flange. It is composed of a peripheral laminated rubber 4 having a hollow cross-sectional shape arranged between the flanges 3 and a central laminated rubber 5 arranged in the central portion on the cross section thereof, and the sectional area of the peripheral laminated rubber 4 is the central portion. When the cross-sectional area of the laminated rubber 5 is exceeded, the horizontal rigidity of the seismic isolation device 1 is determined by the peripheral laminated rubber 4, and the cross-sectional shape is hollow and the cross-sectional area is reduced with respect to the plane area. It is possible to prolong the cycle of oneself. Surrounding rubber layer 4 and central rubber layer 5
The sectional shape of is not limited to the circular shape shown in the figure, and may be an elliptical shape or a rectangular shape depending on the installation conditions and the directionality of the function to be set, and the central laminated rubber 5 is also formed into a hollow sectional shape. Sometimes.

As shown in FIG. 2, since the cross-sectional area of the peripheral laminated rubber 4 is much larger than the cross-sectional area of the central laminated rubber 5, the horizontal rigidity of the central laminated rubber 5 does not reach the horizontal rigidity of the seismic isolation device 1. The horizontal rigidity of the peripheral laminated rubber 4 does not contribute so much and becomes dominant over the horizontal rigidity of the seismic isolation device 1. Specifically, in order to prevent the rigidity of the central laminated rubber 5 from being excellent, the cross sectional area of the central laminated rubber 5 is smaller than that of the peripheral laminated rubber 4.
It is set to around 1/10 or less. The cross-sectional area and the outer diameter of the peripheral laminated rubber 4 are relatively larger than those of the central laminated rubber 5, thereby ensuring the horizontal rigidity and bending rigidity of the seismic isolation device 1.

The peripheral laminated rubber 4 bears only the horizontal load without bearing the vertical load of the upper structure S ₁ by applying a tensile force in the axial direction as described later. The central part laminated rubber 5 bears the vertical load.

The peripheral laminated rubber 4 does not bear a vertical load,
Since the horizontal rigidity of the seismic isolation device 1 is determined by the horizontal rigidity, and stability is obtained as described later, the period of the seismic isolation device 1 is extended by setting the cross-sectional area of the peripheral laminated rubber 4 to be small. By design, it can be freely set within the range of 2.0 to 5.0 seconds.

Further, by using a high damping rubber for the central laminated rubber 5, damping is imparted to the seismic isolation device 1, and it is possible to have the seismic isolation bearing and the damper function independently. The seismic isolation device 1 is a spring bearing whose load-deformation relationship is linear. However, even when a high damping rubber is used, the rigidity of the peripheral laminated rubber 4 is dominant, so the restoring force characteristics are close to linear. To maintain.

The cycle of the seismic isolation device 1 increases as the cross-sectional area of the peripheral laminated rubber 4 that bears a horizontal load is smaller, and the stability against bending deformation and buckling in use is better than that of the peripheral laminated rubber 4. Since the outer periphery of becomes higher as it gets farther from the center,
It is effective to increase the distance from the center to the outer circumference in order to prolong the cycle while ensuring stability. Although the wall thickness decreases as the distance from the center to the outer periphery of the peripheral laminated rubber 4 increases, pretension is introduced into the peripheral laminated rubber 4 and no compressive force acts, so no buckling problem occurs. .

A tensile force is preliminarily applied to the peripheral laminated rubber 4 in the axial direction, and by the introduction of this pre-tension, the peripheral laminated rubber 4 is not compressed even when the upper structure S ₁ is supported, and the central portion does not have a compressive force. The laminated rubber 5 is placed in a state of bearing the vertical load of the upper structure S ₁ . Since the peripheral laminated rubber 4 does not bear a compressive force, its buckling is prevented, and it becomes possible to increase the distance to the outer periphery while reducing the cross-sectional area of the peripheral laminated rubber 4, and A reduction in horizontal rigidity and stability can be obtained at the same time.

3 to 5 show an example of a method of introducing pretension into the peripheral rubber laminate 4.

The peripheral laminated rubber 4 is first placed on the lower flange 3 as shown in FIG. 3 and adhered thereto. A joining plate 6 for joining with the upper flange 2 is arranged along the end face on the upper end of the peripheral laminated rubber 4, and is bonded to this upper end. As shown in FIG. 4, a central laminated rubber 5 having a size larger than that of the peripheral laminated rubber 4 is installed in the central portion of the peripheral laminated rubber 4. The central laminated rubber 5 is bonded to the upper flange 2 in advance, or is bonded to the lower flange 3 by bolts 7, and is similarly bonded to the lower flange 3.

Here, as shown in FIG. 5, the upper flange 2 is pushed down to the position of the joining plate 6 and the central laminated rubber 5 is pressed.
A compressive force is applied to the upper flange 2 and the joining plate 6 in this state, which are joined to each other by the bolts 7 and released as they are, whereby the peripheral laminated rubber 4 is pulled by the upper flange 2 by the restoring force of the central laminated rubber 5. , The pretension is introduced in the axial direction. 3 to 5 show the simplest method, and the method of introducing pretension is not limited to this.

The central laminated rubber 5 bears the vertical load of the upper structure S ₁ within a range where the tensile force is introduced into the peripheral laminated rubber 4 to cancel the tensile force.

At the same time as the introduction of the tensile force to the peripheral laminated rubber 4, the pre-stress remains in the central laminated rubber 5,
A high compressive force acts on the central laminated rubber 5 when supporting the upper structure S ₁ , but the central laminated rubber 5 behaves in the horizontal direction simultaneously with the peripheral laminated rubber 4 via the upper flange 2 and the lower flange 3. Therefore, since the peripheral laminated rubber 4 that does not buckle is restrained against horizontal deformation, the central laminated rubber 5 is also prevented from buckling, and the seismic isolation device 1 bends or buckles. In contrast, the upper structure S ₁ is supported in a stable state and vibrates in a long cycle.

[0024]

The present invention is as described above, and by applying a tensile force to the peripheral laminated rubber having a hollow cross-section in advance in the axial direction, the peripheral laminated rubber is only subjected to a horizontal load and at the same time buckling By overcoming the problem and enabling its smaller cross-section and thinner wall, the period of the seismic isolation device can be extended. In particular, since the peripheral laminated rubber is kept in a non-buckled state, stability and low rigidity can be achieved at the same time by increasing the distance to the outer periphery, so the cycle can be set freely. .

Further, since the central laminated rubber having a relatively small sectional area bears the vertical load, it serves as a long-period spring bearing even for a structure having a relatively small vertical load. It can be used as a supporting device such as a dynamic vibration absorber installed on an object and absorbing vibration in synchronization with the structure.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a manufacturing example of a seismic isolation device of the present invention.

2 is a cross-sectional view of FIG.

FIG. 3 is a vertical cross-sectional view showing a first step of an example of introducing a tensile force to a peripheral laminated rubber.

FIG. 4 is a vertical cross-sectional view showing the next step of FIG. 3 in which a central laminated rubber is installed.

FIG. 5 is a vertical cross-sectional view showing the next step of FIG. 4 in which the peripheral laminated rubber and the upper flange are joined.

FIG. 6 is an elevational view showing the installation status of the seismic isolation device.

[Explanation of symbols]

S ₁ …… upper structure, S ₂ …… lower structure, 1 …… seismic isolation device, 2 …… upper flange, 3 …… lower flange, 4 ……
Peripheral laminated rubber, 5 ... Central laminated rubber, 6 ... Joining plate, 7 ... Bolt.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Katsuyasu Sasaki 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. Kashima Construction Co., Ltd.

Claims (1)

(57) [Claims] 1. An upper flange and a lower flange fixed to an upper structure and a lower structure, respectively, and a peripheral laminated rubber having a hollow cross-section, which is arranged between the upper flange and the lower flange and mainly bears a horizontal load, The peripheral laminated rubber is arranged in the center of the cross section of the peripheral laminated rubber, and is mainly composed of the central laminated rubber that bears the vertical load of the upper structure. The peripheral laminated rubber is preliminarily given a tensile force in the axial direction. A seismic isolation device characterized by being installed.