JPH11303456A - Construction of vibration isolation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the rolling of a building and a floor at the time of the generation of an earthquake by inserting a steel ball supporting an upper structure between the upper structure and a lower structure and rubber boards to the upper and lower sections of the steel ball. SOLUTION: Steel balls 1 supporting an upper structure B are inserted between the upper structure B and a lower structure A and rubber boards 2A, 2B to the upper and lower sections of the steel balls. The tabular rubbers 2A, 2B are brought to the state, in which they are recessed, at the pressure of the steel balls 1 at the normal time. Since the lower structure A is quaked horizontally at the time of an earthquake, the balls 1 are rolled freely in the horizontal direction. Recessed sections in the tabular rubbers are moved at all times by rolling. Consequently, rubber board 2A, 2B themselves absorb seismic energy (displaying a damping effect), and horizontal displacement is reduced. Accordingly, acceleration transmitted to the upper structure is lowered to approximately one third or less of the acceleration of the lower structure, and seismic force is hardly transmitted to the upper structure. Since the cost of the rubber boards and the steel balls is reduced, the economical construction of vibration isolation having high safety can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be used for relatively light buildings (for example, buildings with 3 stories or less, detached houses, etc.) and floors of buildings, and can be used to reduce the rolling of buildings and floors when an earthquake occurs. It is related to seismic isolation structure to prevent or mitigate.

[0002]

2. Description of the Related Art Heretofore, as this type of seismic isolation device, there have been proposed some devices in which a hard ball (bearing) made of steel or the like for supporting an upper structure is inserted between an upper structure and a lower structure. Various types of inventions have been made for a damping device that limits the amount of rolling of a steel ball because the rolling is difficult to stop because the friction resistance is small with only a hard ball. As a specific example, as in JP-A-2-285176, a viscous body (a material having a rust-proof effect such as grease) is used for a ball bearing that supports the weight of an upper structure. These examples have technical problems in the following points.

[0003]

The above prior art is inferior to the present invention in the following points. Because a hard ball (bearing) does not deform itself,
The contact area between the upper structure and the lower structure and the sphere becomes very small, and the compressive stress at the contact portion tends to be excessive. If the compressive stress is high, local dents (dents) are likely to occur on the sphere and on the upper and lower bearings in contact with the sphere, and the rolling motion is not smooth. Therefore, it is necessary to take measures such as increasing the number of balls, increasing the diameter of the balls, and reinforcing the contact points with the steel balls of the upper and lower structures with a thick steel material, which is economically high. Since a hard sphere does not deform itself, if there is slight differential subsidence (partial subsidence) in the lower structure, the sphere and the upper structure may be separated. As a result, the load distribution of the ball and the lower structure is biased. During construction, accuracy errors in the vertical direction of the lower and upper structures occur. For this reason, problems such as an excessive compression force being generated on the hard sphere and a gap being generated between the sphere and the upper structure are likely to occur. Since a hard sphere does not deform itself, it is necessary to take measures to reduce the displacement caused by the earthquake. One is to insert a damping mechanism (damper) to absorb seismic energy and reduce the amount of shaking. The other method is to reduce the displacement of the sway by making the lower bearing that supports the hard sphere have a gentle concave shape and changing the seismic energy to the potential energy of the upper structure when shaking due to an earthquake. This 2
Both approaches are technically effective, but lead to higher costs.

[0004]

In order to solve the above-mentioned problems, according to the present invention, a steel ball for supporting an upper structure between an upper structure and a lower structure, and a seismic isolation device in which rubber plates are inserted above and below the steel ball. Features a structure. In the present invention, between the upper structure and the lower structure, a columnar rubber may be fixed via a mounting plate at a place different from the place where the steel ball and the rubber plate are provided. Further, the present invention is characterized by a seismic isolation structure in which steel balls are inserted between an upper floor and a lower floor, and rubber plates are inserted above and below the steel balls. (Function) According to the seismic isolation structure of the present invention,
Is in a state in which the plate-like rubber is dented into a concave shape due to the pressure of a steel ball. During an earthquake, the substructure sways horizontally, so the ball rolls freely in the horizontal direction. By rolling,
The concave portion of the rubber plate moves constantly. As a result, the rubber plate itself (exhibiting a damping effect) absorbs seismic energy and reduces horizontal displacement. At this time, since the pressure of the steel ball is transmitted to the upper and lower structures via the rubber plate 2, the contact area is large, and the depression of the steel ball due to local stress concentration and the depression of the upper structure are reduced. Does not occur.
The acceleration transmitted to the upper structure is reduced to about 1/3 or less of the acceleration of the lower structure, and almost no seismic force is transmitted to the upper structure. With the ball and rubber plate alone, when horizontal displacement occurs during an earthquake, there is no force (restoring force) to return to the original state, so there is a high possibility that permanent (residual) displacement will occur after the earthquake. There are the following two solutions to this problem. (1) If permanent horizontal (residual) displacement occurs after the earthquake, return it to its original position with a jack or the like. (2) Avoid permanent horizontal (residual) displacement after an earthquake. Specifically, by fixing a cylindrical rubber having elastic spring characteristics between the upper and lower structures, a restoring force is secured, and after an earthquake, it is returned to its original position. (Claim 2 of the present invention)
Is the abstract of this second plan)

[0005]

(Embodiment 1) In FIGS. 1 and 2, a steel ball 1 for supporting an upper structure is inserted between an upper structure B and a lower structure A. Normally (always), the pressure of the steel ball causes the plate-like rubber to be dented in a concave shape.
Arrange the ball 1 so that the weight borne by the ball 1 is equal,
By making the amount of depression of the rubber plate 2 equal, uneven settlement (variation in settlement) is prevented from occurring in the lower part of the upper structure B. During construction, accuracy errors in the vertical direction of the lower and upper structures occur. However, the softness of the rubber plate 2 absorbs this accuracy error, so that the workability is good. During an earthquake, the lower structure A receives acceleration horizontally, so that the ball 1 rolls freely in the horizontal direction. By rolling, the concave portion of the rubber plate 2 is constantly moved. As a result, the rubber plate 2 itself (exhibiting the damping effect) absorbs the seismic energy and reduces the horizontal displacement. As a result, the acceleration transmitted to the upper structure A is reduced to about 1/3 or less of the acceleration of the lower structure, and the seismic force is hardly transmitted to the upper structure A.

[0006] As the ball 1 rolls, the recessed portion of the rubber plate returns to its original position and repeats the recessing again. The seismic energy is converted into the kinetic energy of the upper building once,
Thereafter, it is absorbed by the deformation of the rubber plate 2. Due to this effect, the rolling of the ball 1 does not continue indefinitely, and even in the case of a large earthquake, the ball 1 falls within a range of ± 30 cm or less from the original position.
FIG. 5 shows the restoring force characteristics of the seismic isolation structure of FIG. Rubber plate 2
With the sphere 1 alone, when a horizontal displacement occurs during an earthquake, there is no force (restoring force) to restore the horizontal displacement, so there is a high possibility that a permanent horizontal (residual) displacement will occur after the earthquake. If a permanent (residual) displacement occurs after the earthquake, it can be easily returned to the original position by returning it with a jack or the like.

(Embodiment 2) In FIG. 3, steel balls 1 for supporting the upper structure A are inserted between the upper structure B and the lower structure A, and the upper and lower bearings of the steel balls 1 are plate-shaped. Rubber 2 is installed, and a columnar rubber 3 is provided between the upper structure and the lower structure.
The seismic isolation structure in which is fixed by the mounting plate 4 and the stud bolt 5 is shown.

[0008] The columnar rubber 3 causes a shear deformation during an earthquake, and functions to return to the original position. FIG. 6 shows the restoring force characteristics of the seismic isolation structure of FIG. The cylindrical rubber 3 shows a linear (elastic) behavior, and the device of the rubber plate 2 and the sphere 1 shows characteristics as shown in FIG. With the rubber plate 2 and the ball 1 alone,
When horizontal displacement occurs, there is no restoring force, so there is a high possibility that permanent horizontal (residual) displacement after the earthquake will occur. By attaching the columnar rubber 3, the upper structure B can be almost returned to its original position even after the earthquake.

(Embodiment 3) FIG. 4 shows a lower floor C of a building.
1 shows a base-isolated floor structure in which a steel ball 1 is disposed on the upper surface and an upper floor D is placed thereon. Plate-shaped rubber 2 is installed on the upper and lower bearings of the steel ball 1. FIG. 2 is an invention for making the entire building seismically isolated, while FIG. 4 is an invention for making a part of the floor in the building seismically isolated. Other details are the same as in the first embodiment.

[0010]

According to the present invention, the following effects can be obtained. During an earthquake, a horizontal acceleration acts on the lower structure, and the ball 1 rolls. Therefore, the acceleration transmitted to the upper structure is reduced to about 1/3 or less of the acceleration of the lower structure, and the seismic force is hardly transmitted to the upper structure (seismic isolation effect). Since the rubber plate 2 and the steel ball 1 are inexpensive, a very simple mechanism can easily realize a much more economical and highly safe seismic isolation structure as compared with the conventional seismic isolation device. As the ball 1 rolls, the recessed portion of the rubber plate 2 moves, and the portion that receives compressive strain constantly changes. The seismic energy is converted into the kinetic energy of the upper building once,
Thereafter, the deformation energy of the rubber sheet 2 is changed to heat energy. Due to this effect, the rolling of the ball 1 does not continue forever and does not exceed the range of ± 20 to 30 cm from the original position. The dent amount of the rubber plate 2 may change due to uneven settlement (partial settlement) of the lower structure.
The upper structure is supported stably without leaving, so it can cope with uneven settlement of the lower structure. During construction, accuracy errors in the vertical direction of the lower and upper structures occur. In a conventional mechanism for supporting a steel ball with a rigid bearing, this accuracy error is a problem, but the softness of the rubber plate 2 absorbs this accuracy error, so that the workability is good.

[Brief description of the drawings]

FIG. 1 is a diagram of a house in which the present invention is implemented.

FIG. 2 is a longitudinal sectional view showing an embodiment of a bearing in the seismic isolation structure according to the present invention.

FIG. 3 is a longitudinal sectional view showing an embodiment of a bearing in the seismic isolation structure according to the present invention.

FIG. 4 shows a longitudinal section of an embodiment in which only the floor is seismically isolated.

FIG. 5 shows the restoring force characteristics of the seismic isolation structure of FIGS.

FIG. 6 shows the restoring force characteristics of the seismic isolation structure of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel ball 2 Rubber plate 3 Cylindrical rubber 4A, 4B Mounting plate 5 Stud bolt A Lower structure B Upper structure

Claims (3)

[Claims] 1. A steel ball 1 for supporting an upper structure between an upper structure B and a lower structure A, and rubber plates 2A, 2B above and below the steel ball 1.
The seismic isolation structure with the inserted. 2. A columnar rubber 3 is fixed between the upper structure B and the lower structure A at a position different from the position where the steel ball 1 and the rubber plates 2A and 2B are arranged via mounting plates 4A and 4B. The seismic isolation structure according to claim 1. 3. A steel ball 1 between an upper floor D and a lower floor C;
Seismic isolation structure with rubber plates 2C and 2D inserted above and below steel ball 1.