JP3114603B2 - 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 seismic isolation device used for a structure, particularly an office building, an apartment house, a general house or the like.

[0002]

2. Description of the Related Art Conventionally, various types of seismic isolation devices have been developed to suppress shaking of various structures due to earthquakes.
Some have been put to practical use. As this type of seismic isolation device, a laminated rubber isolator, an air spring, and a metal coil spring are generally used. Such a seismic isolation device is interposed between a foundation and a structure to be isolated, and absorbs a horizontal component and a vertical component of an earthquake input energy as elastic strain energy.

[0003] This type of seismic isolation device is intended only for inputting horizontal vibration (so-called rolling) to a building, and does not deal with vertical vibration (so-called pitching). Recently, in the Great Hanshin Earthquake, which caused great damage in Japan, collapses of buildings and other structures were observed everywhere, but it was reported that such collapses were caused not only by horizontal vibration but also by vertical vibration. Has been made.

By the way, in order to simultaneously isolate the horizontal component and the vertical component of the input energy of an earthquake using a conventional seismic isolation device, a thick-type laminated rubber is used, or both components are simultaneously isolated. It is conceivable to use an air spring or a metal coil spring having characteristics. Such a conventional seismic isolation device exhibits a seismic isolation effect in the frequency range of 3 Hz to 5 Hz or more in the horizontal direction and 7 Hz to 10 Hz or more in the vertical direction.

[0005]

However, the vertical vibration transfer function of the structure which is isolated by the laminated rubber has a first natural period of more than 1 second and a second natural period of 0.3 second, The horizontal vibration transfer function has a first-order natural period of 1.
The input period in the horizontal and vertical directions of the earthquake is 1 second to 0.1 second, while the second natural period is 3 seconds and the secondary natural period is 0.3 seconds. There is a possibility that the vibrations are included in this input period band and resonate, and the seismic input is amplified. To suppress the resonance, it was necessary to provide a vertical damper for suppressing the vertical vibration, and to surely suppress the resonance, an excessively large vertical damper had to be provided. Such a problem similarly exists in an air spring.

Accordingly, an object of the present invention is to provide a seismic isolation device capable of reliably suppressing resonance with seismic waves without providing an excessive vertical damper.

[0007]

In order to achieve the above object, the invention according to claim 1 is directed to a horizontal seismic isolation part having a spring characteristic of low rigidity in the horizontal direction and high rigidity in the vertical direction, and a horizontal direction. A seismic isolation device comprising any one of vertical seismic isolation units having a high rigidity and a low vertical rigidity having a spring characteristic between the foundation side and the seismic isolation target side, A characteristic characterized by imparting a spring characteristic between the object side and the horizontal direction or the vertical direction, in which the rigidity in the direction of low rigidity is low and the rigidity in the other direction is high. It is.

Further, the invention according to claim 2 is characterized in that the spring characteristic is provided by a leaf spring formed by processing a thin steel plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention basically provides a horizontal seismic isolation section having a spring characteristic of low horizontal rigidity and high vertical rigidity, and a high horizontal rigidity and low vertical rigidity. A seismic isolation device including one of vertical seismic isolation units having spring characteristics between a foundation side and a seismic isolation target side,
Between the foundation side and the seismic isolation target side, the rigidity in the direction in which the rigidity is low among the horizontal or vertical rigidities is low,
In addition, a spring characteristic having high rigidity in other directions is provided.

FIG. 10 shows a horizontal seismic isolation section such as a laminated rubber isolator which is disposed below and mainly has a horizontal seismic isolation function, and air which is disposed above and mainly has a vertical seismic isolation function. Fig. 3 schematically shows a seismic isolation structure which is seismically isolated by a two-layer seismic isolation device including a vertical seismic isolation part such as a spring. Note that the horizontal seismic isolation part and the vertical seismic isolation part are of a series spring coupling method via a coupling part having mass. Here, the vertical rigidity of the horizontal seismic isolation part is Kv1, the horizontal rigidity Kh1, and the rotational rigidity Ko1, and the vertical rigidity Kv2, the horizontal rigidity Kh2, and the rotational rigidity Ko2 of the vertical seismic isolation part.

In such a vibration system, when all the rigidities of the horizontal seismic isolation part and the vertical seismic isolation part are reduced, the vibration transfer function representing the seismic isolation effect has a first natural period, a second natural period (others). The characteristic vibration of rocking) has excellent characteristics. Since the primary natural period is originally set to be longer than the input period, the amount stimulated by the earthquake input is small,
The next natural period resonates with the input wave component, and the seismic isolation effect is impaired.

Therefore, in the present invention, the rigidity of the horizontal seismic isolation part and the vertical seismic isolation part is adjusted so that the secondary natural period is reduced while avoiding the input vibration characteristics of the earthquake.

For example, in the vibration system shown in the above figure, if the secondary natural period avoids the input period band of the earthquake by increasing the period in the vertical direction, the vertical rigidity of the vertical seismic isolation part is reduced. To increase the vertical rigidity of the horizontal seismic isolation part sufficiently, and to increase the period in the horizontal direction, reduce the horizontal rigidity of the horizontal seismic isolation part to reduce the horizontal rigidity of the vertical seismic isolation part. By making the stiffness sufficiently high, the secondary natural period in both the horizontal response and the vertical response is moved to a period band where the input wave component of the earthquake is small, resulting in a good seismic isolation response.

As described above, the horizontal response and the vertical response are made to correspond to the seismic wave by providing the spring characteristic having the low rigidity in the low rigidity direction and the high rigidity in the other directions among the rigidities in the horizontal direction or the vertical direction. Good seismic isolation response without resonance can be obtained. As a specific example for providing such a spring characteristic, a leaf spring formed by processing a thin steel plate is provided between the base side and the seismic isolation target side, and a link made of a brace material is provided between the both. It is conceivable to provide a mechanism or to provide a means for restraining the horizontal movement of the movable part when the vertical seismic isolation part is an air spring.

As the horizontal seismic isolation part and the vertical seismic isolation part, known ones such as a laminated rubber isolator, an air spring, a metal spring, and a coil spring are used. These generally have high rigidity in one direction (eg, horizontal direction) (soft) and low rigidity in the other direction (eg, vertical direction) (hard).
It has such a spring characteristic. Therefore, the rigidity in the direction of low rigidity out of the rigidity in the horizontal direction or the vertical direction, that is, when these seismic isolation devices are used, a spring characteristic having low rigidity in the vertical direction and high rigidity in the horizontal direction is required. I just need.

The shape of the leaf spring is such that two thin steel plates are bent in the thickness direction and one end surfaces thereof are fixedly fastened to each other so that the other end surfaces face each other with a predetermined gap. Various types such as notched one thin steel plate, bent into a Y-shape when viewed from the thickness direction, and one thin steel plate cut into a coil shape Things can be adopted. These leaf springs all have high rigidity in the horizontal direction and low rigidity in the vertical direction.

[0017]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 is a sectional view of the seismic isolation device according to the present invention, FIG. 2 is a view taken in the direction of the arrow II in FIG. 1, FIG. 3 is an enlarged perspective view of a leaf spring, and FIGS. Fig. 5 (a), a correlation diagram between the period representing the seismic effect and the vibration transfer function.
(B) is a correlation diagram between the cycle representing the seismic isolation effect of the present embodiment and the vibration transfer function.

The seismic isolation device comprises a laminated rubber isolator 1 disposed below and having a horizontal seismic isolation function, and an air spring 3 disposed above and having a vertical seismic isolation function. The two-layer structure is disposed at an appropriate position between the foundation 5 and the structure 7 to be isolated.

The laminated rubber isolator 1 is composed of a plurality of disk-shaped steel plates 13, 13 disposed at an appropriate pitch between a pair of disk-shaped plates (lower plate 9, intermediate plate 11) facing in the vertical direction and a rubber (laminated). (Rubber) 15 and 15 are alternately laminated in a sandwich shape. When the earthquake input is transmitted to the foundation 5, the laminated rubbers 15, 15 are deformed mainly as soft springs in the horizontal direction, and absorb the input energy as elastic strain energy.

The air spring 3 is disposed between the upper plate 17 fixed to the bottom of the structure 7 and the intermediate plate 11. The air spring 3 is composed of an air tank (cylinder) 19 in which air of a predetermined pressure is sealed and a piston (not shown) movable inside the air tank 19 in the vertical axis direction, and mainly absorbs vertical earthquake input. Things.

A pair of metal leaf springs 21 is provided between the intermediate plate 11 and the upper plate 17. Each leaf spring 21 has two thin steel plates 21a,
21b is bent in the plate thickness direction and one end faces thereof are fixedly fastened to each other so that the other end faces each other with a predetermined gap therebetween. Each is tied to the plate 17. The leaf spring 21 having such a structure has high rigidity in the horizontal direction (hard) and low rigidity in the vertical direction (soft). By increasing the horizontal rigidity of the air spring 3,
The natural period (particularly the second natural period) with respect to the horizontal and vertical periods (frequency) does not resonate with the input wave component of the earthquake, and a good seismic isolation response can be obtained.

As shown in FIG. 2, the leaf springs 21 have their length directions orthogonal to each other about the air spring 3 so that the horizontal rigidity is high in all directions when the seismic isolation device is viewed in plan. Are located in

The embodiment of the present invention has the above features. The laminated rubber isolator 1 mainly absorbs the horizontal component of the earthquake, and the air spring 3 mainly absorbs the vertical component of the earthquake. In such a vibration system, if the rigidities (horizontal rigidity, vertical rigidity, rotational rigidity) of the laminated rubber isolator 1 and the air spring 3 are reduced without providing the leaf spring 21, the vibration transfer function representing the seismic isolation effect becomes As shown in FIGS. 4A and 4B, the natural vibration of the first natural period and the second natural period (other rocking) has the predominant characteristic. Since the primary natural period is originally set to be longer than the input period, the amount stimulated by the earthquake input is small,
As described above, the next natural period resonates with the input wave component and the seismic isolation effect is hindered.

However, by providing a leaf spring 21 having high rigidity in the horizontal direction and low rigidity in the vertical direction between the intermediate plate 11 and the upper plate 17, the vibration transfer function in the vertical direction and the horizontal direction is reduced. As shown in 5 (a) and 5 (b), the secondary natural period can be reduced by avoiding the input vibration characteristics of the earthquake, and the horizontal response and the vertical response should be good seismic isolation responses that do not resonate with seismic waves. Can be.

The leaf spring 21 has such a characteristic that the smaller the distance between the end faces is compared to the length in the horizontal direction, the higher the horizontal rigidity and the lower the vertical rigidity. When buried in the structure 7, the leaf spring 2
1 is inevitably reduced, so that the leaf spring 21
Can be shortened in the horizontal direction, and downsizing of a leaf spring having the same spring characteristics can be achieved.

FIG. 6 shows another embodiment. In this embodiment, instead of the leaf spring in the embodiment shown in FIGS. 1 and 2, a pantograph-type link mechanism composed of brace members 23 is added between the foundation 5 and the structure 7. This link mechanism has a high rigidity in the horizontal direction and a high rigidity in the vertical direction by setting the distance a between the air springs 3 and 3 in FIG. 5 sufficiently larger than the distance b between the foundation 5 and the structure 7. Has low spring characteristics, and has the same operation and effect as the above-described leaf spring 21.

FIG. 7 shows still another embodiment. In this embodiment, the laminated rubber isolator 1 is provided between the foundation 5 and the structure 7, and the seismic isolation in the same direction is achieved mainly by increasing the period in the horizontal direction.
Further, a metal leaf spring 25 having a shape as shown in FIG. Leaf spring 25
Is formed by bending a single thin steel plate 25a in the plate thickness direction and fixing joining plates 25b, 25b at both ends, and binding the respective plates 25a, 25b to the foundation 5 and the structure 7. By doing so, it has spring characteristics with low horizontal rigidity and high vertical rigidity. The combination of the laminated rubber isolator 1 and the leaf spring 25 can provide the same effects as those of the above-described embodiment, and can make the horizontal response and the vertical response a good seismic isolation response that does not resonate with the seismic wave.

FIG. 9 shows still another embodiment. In this embodiment, the leaf spring 25 in the embodiment of FIG.
In place of the above, a link mechanism including steel bars 27, 27 having spring characteristics having low horizontal rigidity and high vertical rigidity is provided, and the link mechanism is deformed as shown by a broken line in FIG. It has the same effect as the leaf spring.

[0029]

As described above, according to the present invention, between the foundation side and the seismic isolation target side, the rigidity in the direction of lower rigidity in the horizontal or vertical direction is low, and By providing spring characteristics with high rigidity in other directions, the horizontal response and vertical response can be made a good seismic isolation response that does not resonate with the seismic wave without providing an excessive vertical damper. It can be suppressed reliably.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a seismic isolation device according to the present invention.

FIG. 2 is a view taken in the direction of the arrow II in FIG.

FIG. 3 is an enlarged perspective view of a leaf spring.

FIG. 4A is a correlation diagram between a vertical cycle and a vibration transfer function representing a conventional seismic isolation effect. (B) is a correlation diagram between a horizontal cycle representing a conventional seismic isolation effect and a vibration transfer function.

FIG. 5A is a correlation diagram between a vertical period and a vibration transfer function representing the seismic isolation effect of the present embodiment. (B) is a correlation diagram between the horizontal period representing the seismic isolation effect of the present embodiment and the vibration transfer function.

FIG. 6 is a schematic side view showing another embodiment.

FIG. 7 is a schematic side view showing still another embodiment.

FIG. 8 is an enlarged perspective view of a leaf spring in the embodiment of FIG. 7;

FIG. 9 is a schematic side view showing still another embodiment.

FIG. 10 is a diagram schematically illustrating a seismic isolation structure which is seismically isolated by a two-layer seismic isolation device including a horizontal seismic isolation part and a vertical seismic isolation part.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Laminated rubber isolator 3 Air spring 5 Foundation 7 Structure 9 Lower plate 11 Intermediate plate 13 Steel plate 15 Rubber (laminated rubber) 17 Upper plate 19 Air tank 21 Leaf spring (thin steel plates 21a, 21b) 23 Brace material 25 Leaf spring (thin) Steel plate 25a, joining plate 25b,
25b) 27 steel bars

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-194233 (JP, A) JP-A-59-217877 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E04H 9/02 331 F16F 15/04

Claims (2)

(57) [Claims] 1. A horizontal seismic isolation unit having a spring characteristic having a low horizontal rigidity and a high vertical rigidity, and a vertical seismic isolation unit having a high rigidity in the horizontal direction and a low vertical rigidity. A seismic isolation device including any one between the foundation side and the seismic isolation target side, wherein between the foundation side and the seismic isolation target side, the rigidity of the horizontal or vertical rigidity is Low rigidity in low direction,
A seismic isolation device characterized by providing spring characteristics having high rigidity in other directions. 2. The spring characteristic is given by a leaf spring formed by processing a thin steel plate.
Seismic isolation device described in.