JPH1061254A - Three-dimensional vibration isolation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct three-dimensional vibration isolation effectively by inhibiting the pitching of a structure at the time of horizontal vibrations regarding the three-dimensional vibration isolation device of the structure. SOLUTION: Four air springs 1 are installed on a floor 9, slip pads 5 are fixed onto the upper sections of the springs 1, and an upper structure 6 is placed movably in the horizontal direction through sliding plates 7 on an underside. One ends of each arm 2 are connected at the upper ends of each air spring 1 by pins 8, and the other ends of the arms 2 are coupled at the end sections of a main shaft 3. The main shaft 3 is fixed onto the floor 9 through bearings 4. Since pitching is generated when the upper structure 6 is quaked horizontally in the right direction, the left-side air spring 1 receives downward force and the right-side air spring 1 receives upward force and an angular moment is generated, torsion is generated in the main shaft 3 through the left-right arms 2, and the generation of pitching is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional seismic isolation device for simultaneously reducing horizontal and vertical seismic inputs to buildings, steel structures, machinery, box-shaped rooms, floors, and the like.

[0002]

2. Description of the Related Art The following three-dimensional seismic isolation devices having a seismic isolation effect simultaneously in the horizontal and vertical directions have been disclosed, and their outline will be described.

FIG. 5 shows the structure of Japanese Utility Model Laid-Open No. 64-2943. FIG. 5A is an overall side view of the seismic isolation device with the floor mounted thereon, and FIG. 5B is a detailed side view of the seismic isolation device. The sliding plate 404 is fixed on the air spring 401 and the sliding plate 40 is fixed.
4 has a sliding surface 404a. A floor plate 405 is placed on the slip surface 404a via the slip surface 405a, and is close to the outer periphery of the floor plate 405 in the vicinity of the shock absorber 40.
7 are arranged.

FIG. 6 shows a device disclosed in Japanese Patent Application Laid-Open No. 7-71109. FIG. 6 is a cross-sectional view of the seismic isolation device, which has a structure in which a plurality of steel balls 517 rolling on a plane of a steel plate 518 fixed on a floor slab 503 are interposed in the horizontal direction, and an air spring 570 is used to support the floor plate 501.

FIG. 7 shows an apparatus disclosed in Japanese Utility Model Laid-Open No. 4-6344. FIG. 7 (a) is a side view of the entirety, and FIG. 7 (b) is a detailed view of part A thereof. This seismic isolation device is related to a low-floor type tertiary vibration isolation and seismic isolation floor structure, and is mounted on a foundation 601. Fixed floor column 606a
And pulleys 602a and 602b are attached to respective ends of a floor column 606b fixed to the floor beam 607, respectively.
The floor beam 607, ie, the floor, is supported between a and 602b through a wire rope 603 connected to a coil spring 610 supported at both ends from a foundation. Further, the floor beams 60 are added to the highly viscous oil in the oil sump 608 installed on the foundation 601.
7 by immersing the inner cylinder 604 protruding from the lower surface,
The effective space is widened, and vibration isolation and seismic isolation can be performed up to the low frequency range.

[0006]

However, the above-mentioned prior art has the following problems. That is,
In each case, the natural frequency in the vertical direction must be lower than the predominant frequency of the seismic motion in order to exhibit the seismic isolation effect in the vertical direction, and the spring constant of the vertical support members such as air springs is inevitable. Is a low value.

[0007] Specifically, the vertical natural frequency f of the seismic isolation device is given by f = (1 / 2π) √ from the mass m of the structure on the seismic isolation device and the vertical spring constant k of the seismic isolation device. (K / m),
Given by On the other hand, the deflection amount x due to gravity is x = m
g / k = g / (2πf) ² .

Therefore, from the above equation, if the natural frequency of the seismic isolation device is 1 Hz, for example, the amount of deflection due to gravity is about 25 cm. In such a situation, if the machine or structure to be seismically isolated (hereinafter referred to as the upper structure) has a relatively high center of gravity, the upper structure will move only in the horizontal direction when a horizontal seismic motion is applied. It is easy to imagine that there would be pitching that would result in rotational movement. When pitching occurs, even if the seismic isolation effect as designed is obtained at the position of the center of gravity of the structure, not only the vertical motion and horizontal motion due to pitching occur around the periphery, but also the seismic isolation effect is reduced,
In the worst case, the superstructure may fall.

[0009] In any of the above-mentioned disclosures, there is no description regarding the suppression of pitching. Therefore, in order to prevent pitching, it is necessary to increase the vertical spring constant or to make the interval between the vertical springs sufficiently wide. The former impairs the seismic isolation performance, and the latter means that the upper structure with a high center of gravity requires a larger floor space for installing the seismic isolation device, which is disadvantageous in terms of installation space and cost. .

Accordingly, it is an object of the present invention to provide a three-dimensional seismic isolation device capable of suppressing the occurrence of pitching without accompanying an excessive increase in floor space for installation and deterioration of seismic isolation performance in the vertical direction.

[0011]

SUMMARY OF THE INVENTION Therefore, the present invention provides a structure in which a sliding pad is fixed to a floor surface, has a sliding pad on an upper part, and a sliding surface of a bottom surface of a grooved structure to be seismically isolated contacts the surface of the sliding pad. A plurality of air springs on which the body is mounted; one end of each arm is rotatably connected to an upper part of each air spring adjacent to each other, and the other ends of the arms adjacent to each other are connected by a main shaft; Provided is a three-dimensional seismic isolation device, comprising: a torsion bar type stabilizer having the main shaft rotatably mounted on a floor surface.

In the above-described three-dimensional seismic isolation device of the present invention, when, for example, a rightward horizontal seismic motion is applied to the structure, the structure slides on the left and right air springs supporting the structure between the sliding pad and the sliding surface. As a result, the structure moves in the horizontal direction and at the same time receives the rotational moment given by the height of the center of gravity and the horizontal seismic load. Normally, a compressive load due to the weight of the upper structure is applied to each air spring, but the right air spring increases the compressive load due to the rotational moment,
The left air spring reduces the compression load.

As a result, the right-side air spring is reduced in height, and the left-side air spring is liable to be deformed in the opposite phase in which the air spring is deformed in a direction in which the height is increased as compared with the normal case.
Such a deformation causes the rotation of the right arm of the main shaft and the rotation of the left arm, so that the main shaft is twisted,
Since the rotation of the arm is restricted by the torsional rigidity of the main shaft, the movement of the left and right air springs in opposite phases is restricted, and the structure moves in the horizontal direction against the rotational moment, and the occurrence of pitching is suppressed.

On the other hand, when vertical seismic motion acts, each air spring is deformed in the same direction. As a result, each air spring is compressed, and the height of the left and right air springs attached to the ends of the arms at both ends of the main shaft decreases, so that the main shaft 3
Can be easily rotated.

[0015]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a side view of a three-dimensional seismic isolation device according to an embodiment of the present invention, and FIG. 2 is a perspective view thereof. In FIG. 1, the upper structure 6 to be seismically isolated
Is mounted on a slide pad 5 fixed to the upper part of the air spring 1 via the slide plate 7 and a frictional force between the slide pad 5 and the slide plate 7 is fixed through the slide plate 7. When an excessive horizontal load is applied to the upper structure 6, a slip occurs between the slide pad 5 and the slide plate 7, and the upper structure 6 moves in the horizontal direction.

The air springs 1 are provided at four places on a floor 9 as will be described later. An arm 2 is attached to the upper end of each air spring 1 via a rotatable pin 8 at the upper end. The other end of the arm 2 is fixed to the main shaft 3. The main shaft 3 is fixed to a floor 9 via a rotatable bearing 4.

FIG. 2 omits the upper structure 6 and the sliding plate 7 and shows the seismic isolation part in a bird's-eye view. Air springs 1A, 1B, 1C and 1D are installed at four locations around the upper structure. ing.

The air springs 1A and 1B are connected by a main shaft 3A via a pin 8 and an arm 2. Similarly, the main shaft 3B is connected between the air springs 1B and 1C, and the main shaft 3C is connected between the air springs 1C and 1D. The main shaft 3D connects between the air springs 1D and 1A. Each main shaft 3A, 3B, 3C, 3D is rotatably supported on a floor 9 via a bearing 4.

As described with reference to FIGS. 1 and 2, in the present embodiment, the upper structure 6 to be seismically isolated is provided with a sliding pad 5 attached to the upper end of the air spring 1 in the horizontal direction.
It is seismically isolated and supported by a sliding plate 7 attached to the bottom surface of the upper structure 6, and is vertically seismically supported via four air springs 1 so that the air springs 1 vibrate vertically in the same phase. In this case, a stabilizer that does not generate a resistive force but generates a resistive force when vibrating in different phases is configured.

As a first stabilizer, a so-called torsion bar type stabilizer provided with arms at both ends of a main shaft 3 made of a rod or a pipe having a high torsional rigidity is installed on a floor 9 supported by a rotatable bearing 4. I do. As shown in FIG. 2, four air springs 1A, 1B, 1C, 1
One end of each of the two arms 2 is rotatably attached to the upper end of D with a pin 8, and the other end of the arm is fixed to the main shaft. Two upper ends of one air spring 1 whose axial directions are orthogonal to each other Spindle 3 of
Are connected, four air springs 1A, 1B,
A stabilizer is arranged between 1C and 1D and four main shafts 3A, 3B, 3C and 3D.

As the second stabilizer, a sliding pad 5 having a low coefficient of friction is provided at the upper end of each of the air springs 1A to 1D.
And a sliding plate 7 having a horizontal sliding surface fixed to each corresponding bottom surface of the upper structure 6 is brought into contact with the sliding pad 5 to support the air spring 1 and the upper structure 6.

Next, the operation of the above-described embodiment will be described with reference to FIGS. When a horizontal earthquake motion is applied as shown in FIG. 3A, the upper structure 6 slides between the sliding pad 5 and the sliding plate 7 and moves in the horizontal direction, and at the same time, the height of the center of gravity and the horizontal earthquake. Receives rotational moment given by load. Normally, a compressive load due to the weight of the upper structure 6 is applied to each air spring 1,
In the right air spring 1R, the compression load increases due to the rotational moment, and in the left air spring 1L, the compression load decreases.

As a result, the right-side air spring 1R decreases in height, and the left-side air spring 1L attempts to generate a reverse-phase deformation in which the height of the air spring is increased in a direction of increasing the height. Such a deformation causes the arm 2R to rotate in the direction of arrow A on the right side of the main shaft and the rotation in the direction of arrow B on the left arm 2L as shown in FIG. 3 (b), so that the main shaft 3 is twisted. Since the rotation of the arms 2L, 2R is restricted by the torsional rigidity of the main shaft, the air spring 1L,
The 1R reverse phase motion is restrained, and the upper structure 6 moves in the horizontal direction against the rotational moment, thereby suppressing the occurrence of pitching.

On the other hand, as shown in FIG. 4 (a), when a vertical seismic motion acts, each air spring 1R, 1L is deformed in the same direction. FIG. 4 shows a case where a downward earthquake load is applied. However, the air springs 1R and 1L are compressed, and the arms 2R and 2L at both ends of the main shaft 3 as shown in FIG.
As the heights of the air springs 1R and 1L attached to the ends of the main shaft 3 decrease, the main shaft 3 rotates in the bearing 4 in the direction of the arrow.

According to the operation described above, when horizontal seismic force in the x direction is applied to the upper structure 6 in FIG. 2, pitching occurs in the xz plane. In this case, the main shafts 3 A and 3
When C suppresses pitting and horizontal seismic force in the y direction is applied, the main shaft 3B and the main shaft 3D exhibit an effect of suppressing pitting in the yz plane.

When a vertical seismic load is applied, all the air springs 1A to 1D vibrate in the same phase, and are supported by the main shafts 3A to 3D bearings 4 to rotate freely. Does not interfere with function.

[0027]

As specifically described above, the present invention has a plurality of sliding pads having a sliding pad on an upper portion, and a structure on which the sliding surface of the bottom of the structure comes into contact with the surface of the sliding pad. One end of each arm is rotatably connected to the upper part of the air spring and the air spring adjacent to each other, and the other end of the arm adjacent to each other is connected by the main shaft, and the main shaft is rotatably connected to the floor. Since the structure is provided with the torsion bar type stabilizer attached, the three-dimensional seismic isolation function can be effectively achieved by suppressing the pitching generated in the structure during horizontal vibration.

[Brief description of the drawings]

FIG. 1 is a side view of a three-dimensional seismic isolation device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a three-dimensional seismic isolation device according to one embodiment of the present invention.

3A and 3B are diagrams illustrating an operation of the three-dimensional seismic isolation device according to the embodiment of the present invention during horizontal vibration, wherein FIG. 3A is a side view and FIG. 3B is a perspective view.

FIGS. 4A and 4B are diagrams illustrating the operation of the three-dimensional seismic isolation device according to the embodiment of the present invention during vertical vibration, wherein FIG. 4A is a side view and FIG.

5A and 5B show an example of a conventional three-dimensional seismic isolation device, wherein FIG. 5A is an overall side view, and FIG. 5B is a detailed side view of an air spring portion.

FIG. 6 is a cross-sectional view of an air spring section showing another example of the conventional three-dimensional seismic isolation device.

FIG. 7 shows another example of a conventional three-dimensional seismic isolation device,
(A) is an overall side view, and (b) is a detailed view of a portion A thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air spring 2 Arm 3 Main shaft 4 Bearing 5 Sliding pad 6 Upper structure 7 Sliding plate 8 Pin 9 Floor

Claims (1)

[Claims] 1. A plurality of air springs fixed to a floor surface, having a sliding pad on an upper part, and mounting a structure by abutting a sliding surface of a bottom surface of a seismic isolation target grooved structure on a surface of the sliding pad. One end of each arm is rotatably connected to the upper part of each air spring adjacent to each other, and the other end of each adjacent arm is connected by a main shaft, and the main shaft is rotatably connected to the floor. A three-dimensional seismic isolation device comprising a torsion bar type stabilizer attached thereto.