JPH0762363B2 - Seismic isolation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to seismic isolation of large amplitude horizontal vibration due to an earthquake,
The present invention relates to a seismic isolation device that can realize vibration isolation of small amplitude vibrations of relatively high frequency such as road vibrations.

<< Prior Art >> A recent seismic isolation device is a device having a combination structure of a normal laminated rubber and a steel damper (see, for example, JP-A-62-63775).
In addition to (for example, Japanese Laid-Open Patent Publication), a high damping laminated rubber having a damper function tends to be adopted. This high-damping laminated rubber imparts appropriate vibration characteristics to the building by setting its physical characteristics such as rigidity (spring constant) and damping constant, and at the same time exhibits appropriate vibration damping performance. While preventing damage, due to the above settings, it exerts relatively large rigidity in the horizontal and vertical directions against small horizontal movements and vertical movements during wind loads and small earthquakes. A favorable vibration damping effect cannot be obtained.

<< Problems to be Solved by the Invention >> As described above, the high-damping laminated rubber exhibits relatively large rigidity not only in the horizontal direction but also in the vertical direction with respect to vibration of a small amplitude. The natural frequency of the building given by the damping laminated rubber becomes high. As a result, the predominant vibration component is 10 to 20HZ, which is a comparatively high frequency especially in the case of minute disturbance vibrations in the vertical direction due to automobiles and railways. Then, when it enters the range of about 10 to 20HZ,
Buildings resonate and amplified vibrations tend to occur. Of course, the same thing can be said for a small disturbance vibration in the horizontal direction.

The present invention has been devised to effectively solve the above-mentioned problems, and its purpose is to provide a seismic isolation device that has both vibration isolation performance for small amplitude vibration and seismic isolation performance for large amplitude vibration. To provide.

<< Means for Solving the Problem >> In order to solve the above-mentioned problems, the present invention is a seismic isolation device in which a laminated rubber and a steel damper are arranged between a building lower portion and a foundation, and when the laminated rubber has a small amplitude. The rigidity of the laminated rubber is set so that the natural frequency in the vertical direction of the building when the amplitude is small is about 4 to 6 HZ, and the rigidity of the laminated rubber is set, and 1 mm horizontally at the connection between the end and the bottom of the building or the foundation
A gap of not less than 2 cm is formed.

<Operation> With the seismic isolation system constructed as described above, the rigidity of the laminated rubber is set so that the natural frequency in the vertical direction of the building is about 4 to 6HZ, so a large earthquake that is prominent near 10HZ will not occur. Of course, the resonance of the building can be prevented even with respect to the vertical disturbance vibrations on the higher frequency side than this. Further, since the damping constant of the laminated rubber is set to about 5% when the amplitude is small, it is possible to sufficiently remove the minute disturbance vibrations in the horizontal and vertical directions. At this time, the damping force of the laminated rubber can assist the damping force of the steel damper when the horizontal vibration is large, that is, the damping constant of the laminated rubber is about the same as in the conventional seismic isolation device using the combination of the laminated rubber and the steel damper. Since it is 5%, it can be added to the required damping constant of the seismic isolation device as a whole, reducing the burden on the steel damper and achieving a cost reduction of the seismic isolation device by reducing the number of dampers installed. You can also

<< Example >> An example of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a plurality of seismic isolation devices 1 according to the present invention are arranged between a lower part 2 of a building and a foundation 3. The seismic isolation device 1 is composed of a laminated rubber 4 supporting a load of a building and a plurality of steel dampers 5 arranged around the laminated rubber 4. Explaining the laminated rubber 4, it is made by alternately laminating a rubber plate and a steel plate, but unlike a general laminated rubber, it is approximately 5 in the horizontal and vertical directions during small-amplitude vibration.
It is composed of a damping type with a damping factor of%, and unlike the normal high damping type laminated rubber, the natural frequency in the vertical direction of the building is 4
The rigidity is designed so that the natural frequency in the horizontal direction is ~ 6Hz and below 1Hz.

On the other hand, the steel damper 5 is not different from the usual one, and in this embodiment, the one having a maximum damping constant of about 5% is used. However, a gap 8 of 1 mm or more and less than 2 cm, preferably about 1 cm, is formed in the horizontal direction at the joint between the lower end 5a of the steel damper 5 and the foundation 3, and the lower part 2 of the building and the foundation 3 are relatively several mm.
As long as the above horizontal displacement does not occur, the damping action of the steel damper 5 does not occur. In addition, a spherical bearing 6 is arranged at a portion where the steel damper 5 abuts.

In FIG. 2 (A), a graph of the relationship of the displacement (deformation) δ with respect to the vertical load Q of the conventional damping laminated rubber is shown by a broken line, and the vertical direction Q of the damping laminated rubber of the present invention with respect to the vertical load Q is shown. A graph of the relationship of the displacement δ is shown by a solid line, and each graph is shown separately in FIGS. 2B and 2C. First, the vibration isolation at a small amplitude due to traffic vibration or the like in the range in which the vertical load Q is small and therefore the displacement δ is small is shown near the coordinate origin. 6H
In the laminated rubber 4 tuned to z, the inclination is small in the load-displacement relationship (see the dashed line b in the figure), whereas the conventional one with the vibration isolation period set to 10 to 12 Hz has a large inclination ( (See the two-dot chain line c in the figure). Since the smaller the inclination is, the greater the vibration absorbing effect of the laminated rubber is, it can be seen that the laminated rubber 4 of the present invention exhibits a greater vibration damping effect than the conventional one.

On the other hand, the seismic isolation during large amplitude due to an earthquake in the range where the vertical load Q is large and therefore the displacement δ is large is shown at a position distant from the coordinate origin. (See the solid line a in the figure). That is, it is understood that even the laminated rubber 4 of the present invention exhibits a seismic isolation effect comparable to the conventional one.

As compared with the case of the conventional high damping laminated rubber, the natural vibration frequency of the laminated rubber 4 of the present invention is about 6HZ as shown in FIG. 3, so the peak of the transmission ratio is about 6HZ. As a result, the transmission ratio, especially at 10 to 20 Hz, has dropped significantly compared to the past.

Further, comparing the speed response to traffic vibration, in the conventional high damping laminated rubber, a large speed response is generated by resonating with the predominant component of the disturbance vibration in the vicinity of 10HZ, but in the laminated rubber of the present invention, it is in the vicinity of 10HZ. 6H, which does not cause resonance with the superior component
Since the disturbance vibration component is rapidly decreasing near Z, the velocity response is very small even near the natural frequency 6HZ.

Next, the relationship between the horizontal displacement of the seismic isolation preventive device 1 and the damping constant is shown in FIG. As is clear from the figure, in the case of a so-called medium or large earthquake in which the lower part 2 of the building and the foundation 3 are displaced relatively by several mm or more, the lower end 5a of the steel material damper 5 hits the foundation 3 and the damping is 5%. In addition to exerting the action, the laminated rubber 4 also exerts a damping action of 5%, so the total
A damping effect of 10% is obtained. This is the same value as the damping constant of the conventional high damping laminated rubber. Therefore, compared with the seismic isolation device using the high damping laminated rubber, the damping constant of the laminated rubber 4 is half in the present invention, so that the laminated rubber 4 can be easily developed and manufactured at low cost. Further, as compared with an ordinary seismic isolation device in which laminated rubber and a steel damper are combined, the present invention reduces the horizontal load applied to the steel damper 5, so the steel damper 5
A small number of arrangements are required.

On the other hand, when the relative displacement between the lower part 2 of the building and the foundation 3 is a few mm or less, the steel damper 5 does not work and the laminated rubber 4 alone exhibits a damping effect of about 5%. The natural frequency in the horizontal direction at this time was 2HZ because of the high rigidity in the conventional high damping laminated rubber, but in the laminated rubber 4 of the present invention, the rigidity is reduced by about 10% to about 5%. Since it is possible to lower the horizontal natural frequency and to reduce the natural frequency in the horizontal direction to approximately 1 HZ or less, it is advantageous for improving the vibration damping performance.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the structure of the damping portion of the laminated rubber 4 is a well-known lead plug and the same. Other configurations that exhibit the action may be adopted, and the steel damper 5 is not limited to the rod-shaped damper shown in the embodiment, and a damper formed by a bending plate or a torsion rod may be used.
Further, each numerical value shown in the examples is an example for obtaining a preferable result, and the present invention is not strictly limited to these numerical values, and can be appropriately changed within the range defined in the claims.

<< Effects of the Invention >> As described above, according to the present invention, the laminated rubber is set so that the natural frequency in the vertical direction is 4 to 6 HZ, so that the resonance of the building can be prevented especially against the minute disturbance vibration in the vertical direction. Further, since the damping constant of the laminated rubber is configured to be about 5% at the time of small-amplitude vibration, it is possible to sufficiently remove the minute disturbance vibration in the horizontal and vertical directions. Also, when the horizontal amplitude is large, the damping forces of the laminated rubber and the steel damper are summed, so the horizontal load on the steel damper can be reduced compared to the conventional seismic isolation device that combines the conventional laminated rubber and steel damper. The cost of the seismic isolation device can be reduced by reducing the number of steel dampers.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a side view of a seismic isolation device, and FIG. 2 is a vertical load of a damping laminated rubber of the present invention and a conventional damping laminated rubber. It is the graph which showed the displacement relationship, (A) is the graph which showed these both in superposition, (B) is the graph which showed the load-displacement relationship of the conventional damping laminated rubber, (C) is the damping of this invention. Graph showing load-displacement relation of laminated rubber, Fig. 3 is a comparison diagram of transmission ratio in vertical vibration, Fig. 4 is a comparison diagram of speed response to traffic vibration, and Fig. 5 is a relation diagram of horizontal displacement and damping constant. Is. 1 ... Seismic isolation and vibration control device, 2 ... Lower part of building 3 ... Foundation, 4 ... Laminated rubber 5 ... Steel damper, 6 ... Spherical bearing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Daiichi Yoshihara 4-640, Shimoseito, Kiyose-shi, Tokyo Inside Obayashi Corporation Technical Research Institute, Inc. (56) Reference JP-A-62-63775 (JP, A)

Claims (1)

[Claims] 1. A seismic isolation device in which a laminated rubber and a steel damper are disposed between a lower part of a building and a foundation, wherein the laminated rubber is composed of a damping laminated rubber having a damping constant of about 5% when the amplitude is small, and Set the rigidity of the above laminated rubber so that the natural frequency in the vertical direction of the building when the amplitude is small is about 4 to 6 Hz,
Moreover, a seismic isolation device is characterized in that a gap of 1 mm or more and less than 2 cm is formed in the horizontal direction at the connection between the end of the steel damper and the lower part of the building or the foundation.