JPH0742744B2 - Damping mechanism for seismic isolation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application> The present invention is a seismic isolation that is interposed between an upper structure and a lower structure such as a building and its foundation, and reduces seismic energy transmitted from the lower structure to the upper structure. The present invention relates to a damping mechanism for a device.

<Prior Art> As one of the earthquake-resistant structures of buildings, as shown in FIG.
Isolators 51, 51 that are multiple seismic isolation devices
There is one that is sandwiched between 2 and the lower structure 53 to support the upper structure 52. This isolator 51 has a large vertical loading capacity of rubber and a small horizontal spring rigidity due to shear deformation of rubber. Therefore, the upper structure, which is a heavy object, is stably supported, and the horizontal movement is restricted by the weak spring. Such support increases the horizontal vibration period of the whole system of the structure and makes it larger than the period of the maximum energy component of the earthquake. Therefore, the response acceleration of the building to the input from the earthquake when the earthquake occurs can be reduced.

However, if the upper structure 52 is supported only by the isolator 51, the following problem arises because the horizontal spring force of the isolator 51 is small.

The first problem is that once the upper structure 52 starts to vibrate due to the action of earthquake motion, its vibration amplitude becomes larger than that when the upper structure 52 is directly supported by the lower structure 53 without using the isolator 51. It takes time for the shaking to subside. That is, even if the physical safety is guaranteed, the resident will be in a psychologically uneasy state for a long time, which is unsuitable as a seismic isolation structure for buildings.

The second problem is that when a lateral load such as a wind load of a typhoon is applied to the building, the upper structure 52 may be displaced in that direction, and the stability of the upper structure 52 is not guaranteed.

In order to solve these problems, recently, a damping mechanism composed of an elastoplastic member having a hysteresis characteristic is interposed between the upper structure and the lower structure of a building, and the vibration energy is absorbed by the hysteresis characteristic. A method of doing so has been proposed (JP-A-60-258344).

<Problems to be Solved by the Invention> By the way, in the design of the conventional damping mechanism including the elasto-plastic member, the maximum possible deformation amount is the maximum amplitude of the earthquakes (deformation amount about Design to be 250 mm or more. Therefore, when an earthquake with the smallest amplitude (amount of deformation of about 30 mm or less) occurs, the damping mechanism deforms only within the range of elastic deformation and exhibits hysteresis characteristics to absorb vibration energy. Can not. Therefore, when an earthquake with small amplitude occurs, the building shakes for a long time. Residents become psychologically uneasy.

Therefore, the present invention provides a damping device for a seismic isolation device that combines a plurality of elastic-plastic members having different elastic regions so that the plastic region can be deformed to absorb the vibration energy even when the vibration has a small amplitude and the vibration has a large amplitude. It is intended to provide a mechanism.

<Means for Solving the Problems> In order to achieve the above object, the damping mechanism for a seismic isolation device according to the first aspect of the present invention has one end attached to the upper structure and the other end attached to the lower structure so as not to swing. A first elasto-plastic member formed of an elasto-plastic member, one end of which is attached to the upper structure and the other end of which is oscillatably attached to the lower structure, and the first elasto-plastic member is deformed within an elastic region. And a second elasto-plastic member that is plastically deformed in the working state.

The damping mechanism for seismic isolation device of the invention according to claim 2 has a columnar shape, and one end of which is attached to the upper structure in a non-swingable manner while the other end is attached to the lower structure in a non-swayable manner. A second elasto-plastic member made of a plastic member is formed in a spiral shape and arranged around the second elasto-plastic member, one end of which is attached to the upper structure in a non-swingable manner while the other end is of the lower structure. A plurality of first elasto-plastic members that are attached so as not to swing, and the second elasto-plastic member is plastic while the first elasto-plastic member is deformed within an elastic region. It is characterized by having elasto-plastic characteristics that deform.

The damping mechanism for a seismic isolation device according to a third aspect of the present invention has a spiral shape, one end of which is attached to the upper structure so that it cannot swing, and the other end of which is attached to the lower structure that cannot swing. A second elasto-plastic member formed of a plastic member is spirally formed, and the length along the axis is longer than that of the second elasto-plastic member and is arranged around the second elasto-plastic member and one end thereof is arranged. The second elastic-plastic member is provided with a plurality of first elastic-plastic members that are non-swingably attached to the upper structure and have the other end non-swayably attached to the lower structure. It is characterized in that the first elasto-plastic member has an elasto-plastic characteristic of being plastically deformed in a state of being deformed in the elastic region.

<Action> When the upper structure vibrates slightly due to a small earthquake, the first elasto-plastic member cannot absorb energy because it deforms in the elastic region, but the second elasto-plastic member deforms in the plastic region, so it is small. The vibration energy is absorbed by the hysteresis effect of this second elasto-plastic member. Therefore,
Even if a small-amplitude earthquake occurs, the vibration of the superstructure is attenuated in an extremely short time, and the time until the occupants no longer feel the vibration after the occurrence of the earthquake is extremely short.

On the other hand, when the upper structure vibrates significantly due to a large earthquake, the first elasto-plastic member is plastically deformed, the vibration energy is absorbed by the hysteresis effect, and the vibration of the upper structure is quickly damped. At this time, the second elasto-plastic member plastically fractures, but since there are very few earthquakes that cause such a large vibration, there is no practical problem.

<Example> Hereinafter, the present invention will be described in detail with reference to illustrated examples.

In FIG. 1, 1 is a lower structure, 2 is an upper structure, 3 is a plate fixed to the lower structure 1 by an anchor 4, 5 is a cylindrical lower mounting member fixed to the plate 3, and 6 is an anchor 7 to the upper structure 2. And 8 is a cylindrical upper mounting member fixed to the plate 6 coaxially with the lower mounting member 5.

On the side surfaces of the lower mounting member 5 and the upper mounting member 8, a first
The ends of each of the ring-shaped elasto-plastic members 11, 11, ... Formed by spirally bending a steel rod as an elasto-plastic member are fixed by welding or the like. As shown in FIGS. 1 and 2, the ring-shaped elasto-plastic members 11, 11, ... Are arranged in a petal-like manner so that the gradient directions coincide with each other to form the edge shape of the propeller, that is, in all directions. The braking force is evenly applied to.

On the other hand, fittings 12, 12 are fixed to the upper end surface of the lower mounting member 5 and the lower end surface of the upper mounting member 8. The above fixture 1
Reference numeral 2 includes a flange portion 13 and a cylindrical portion 14, and the tip end of the cylindrical portion 14 expands outward from the inner peripheral surface to facilitate insertion of a rod-shaped elasto-plastic member described later. Above flange 13,13
Are fixed to the upper and lower mounting members 5 and 8 with bolts 15.
Both ends of a rod-shaped elasto-plastic member 17 which is a thick and straight rod-shaped elasto-plastic member 17 formed of lead as a second elasto-plastic member are inserted into the cylindrical portions 14 and 14 of the mounting fixtures 12 and 12, respectively. Is attached so that it cannot swing.

The physical properties of a rod made of an elasto-plastic material are
l, elongation (deformation amount) Δl, strain ε, stress σ, elastic constant E, cross section
Let A be the acting force P, And the amount of deformation Δl is Therefore, it is inversely proportional to the cross-sectional area A and is proportional to the length l. And this relationship holds even in the plastic region only by changing the index. Therefore, in order to cope with a large amplitude, that is, in order to increase the performance (deformability) of increasing the deformation amount, the rod body may be elongated.

Further, in order to withstand a large external force, the cross-sectional area A may be increased. That is, the thick and long rod can withstand a large external force and can increase the amount of deformation.

From this, the ring-shaped elasto-plastic member 11 in which a long rod having a length l is formed into a ring shape so as to be housed in a narrow space.
Shows that the deformability is large. On the other hand, the rod-shaped elasto-plastic member 17 is made of lead. Lead has a narrow elastic region and a large plastic region. Moreover, since the rod-shaped elasto-plastic member 17 has a large cross-sectional area and a short length, it has a small deformability and can withstand a large external force.

According to the damping mechanism for seismic isolation device configured as described above, the ring-shaped elasto-plastic member 1 can be used for an earthquake with a small amplitude (30 mm or less).
.. cannot deform in the elastic region to absorb energy, but the rod-shaped elasto-plastic member 17 deforms in the plastic region and absorbs energy with a hysteresis characteristic. Therefore, when an earthquake with a small amplitude occurs, the damping is promptly performed, and the shaking of the superstructure 2 is quickly stopped. Therefore, the residents are less likely to feel psychological anxiety. Since the rod-shaped elasto-plastic member 17 has a large cross-sectional area and a short length, it gives a large braking force to a small swing.

On the other hand, for earthquakes with a large amplitude, the ring-shaped elasto-plastic members 11, 11, ... Are made of steel rods and have a long length, so the deformability is large, and the large vibration energy due to the hysteresis characteristic due to the deformation of the plastic region. Can be absorbed. Therefore, when an earthquake with a large amplitude occurs, it is quickly attenuated,
The sway of the superstructure 2 stops immediately. In addition, in the case of this large amplitude vibration, the rod-shaped elasto-plastic member 17 has a small deformability, and therefore is destroyed. However, since the frequency of occurrence of such a large amplitude earthquake is extremely low, there is practically no problem even if the bar surface elasto-plastic member 17 is destroyed in the case of a large earthquake.

FIG. 3 is a diagram showing the relationship between the deformation amount and the horizontal force of the ring-shaped elasto-plastic member 11, the rod-shaped elasto-plastic member 17 and the combination thereof in the above embodiment.

4 and 5 show the vibration characteristics of the base-isolated building with and without the rod-shaped elastoplastic member 11 of this embodiment. The experimental data of FIGS. 4 and 5 shows that the lower structure 1 and the upper structure 2 are the isolator in which a rigid plate such as a steel plate and a thin elastic plate such as natural rubber or neoprene rubber are alternately stacked vertically. This is a comparison between a damping mechanism having only the ring-shaped elasto-plastic member 11 and a damping mechanism having the ring-shaped elasto-plastic member 11 and the rod-shaped elasto-plastic member 17 interposed between both large and small earthquakes. is there.

It can be seen from FIG. 4 that when the rod-shaped elasto-plastic member 17 is provided, the acceleration becomes smaller in both large earthquakes and small earthquakes than in the case without it. Also, the fifth
From the figure, it can be seen that when the bar-shaped elasto-plastic member 17 is provided, the displacement becomes smaller in both large earthquakes and small earthquakes than in the case without it.

In the damping mechanism of the above embodiment, the ends of the ring-shaped elasto-plastic member 11 and the rod-shaped elasto-plastic member 17 are attached to the attachment members 5 and 8, respectively.
Since the attachment members 5 and 8 are attached to the lower structure 1 and the upper structure, the damping mechanism can be easily attached and detached.

FIGS. 6 and 7 show the second embodiment, which is a large-diameter ring-shaped elasto-plastic member 21 having a large ring diameter as the first elasto-plastic member and a small ring diameter as the second elasto-plastic member. A small-diameter ring-shaped elasto-plastic member 22 is used. The ring portions 21a, 21a at both ends of the large-diameter ring-shaped elasto-plastic member 21 are arranged on the same vertical line, and are fixed to the upper and lower mounting members 25, 27 by bolts 31. Also, the small-diameter ring-shaped elasto-plastic member 22 has upper and lower ring portions 22a, 22a arranged on the same straight line, and is fixed to the base portions 26, 28 of the mounting members 25, 27 with bolts 32, 32.

Since the small-diameter ring-shaped elasto-plastic member 22 has a short length, the deformability is small, the elastic region is small, and the small-diameter ring elasto-plastic member 22 is plastically deformed and absorbs vibration energy even with vibration having a small amplitude. On the other hand, the large-diameter ring-shaped elasto-plastic member 21 has a large deformability because of its long length,
It absorbs vibration energy by plastically deforming against vibration of large amplitude.

In this way, ring-shaped elasto-plastic members 21, 22 with different ring diameters
By combining the above, it is possible to absorb the vibration energy by deforming the plastic region during both small vibration and large vibration.

In the above embodiment, the first and second elasto-plastic members are connected to the attachment member, but the first and second elasto-plastic members may be separately separated and attached to the upper and lower structures. .

<Effects of the Invention> As is clear from the above, the damping mechanism for a seismic isolation device of the present invention includes a first elasto-plastic member and a second elasto-plastic member.
Since the second elasto-plastic member is plastically deformed in a state where the elasto-plastic member is elastically deformed, the second elasto-plastic member can be plastically deformed to absorb vibration energy with respect to a vibration of a small amplitude, The first elasto-plastic member can be plastically deformed to absorb vibration energy with respect to large-amplitude vibration, and therefore, the superstructure can be quickly stopped even for large earthquakes and small earthquakes.

[Brief description of drawings]

FIG. 1 is a front view of a damping mechanism for a seismic isolation device according to a first embodiment of the present invention, FIG. 2 is a view taken along the line II-II of FIG. 1, and FIG. A force characteristic diagram, FIG. 4 is a diagram showing an acceleration response of the base-isolated building at the time of an earthquake, FIG. 5 is a diagram showing a displacement response of the base-isolated building at the time of an earthquake, and FIG. 6 is a diagram of a second embodiment of the present invention. Front view of damping mechanism for seismic isolation device, Fig. 7 is VII of Fig. 6
-VII line arrow view, FIG. 8 is a figure which shows the seismic isolation structure of a building. 11,12 ... First elasto-plastic member, 17,22 ... Second elasto-plastic member, 5,8,
25, 27 ... Mounting member.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isamu Abe 727-2 Neya, Neyagawa-shi, Osaka (72) Inventor Masaru Otsuka 4-16-4 Azuma Sakuramura, Shinji-gun, Ibaraki Prefecture (72) Inventor Hiroshi Sugimoto Shinji, Ibaraki Prefecture Sakuramura, Azuma 4-16-4 (72) Inventor, Kunio Hayakawa 1-18-5 Sengen, Tsukuba-shi, Ibaraki (56) References JP-A-61-14338 (JP, A)

Claims (3)

[Claims] 1. A first elasto-plastic member comprising an elasto-plastic member, one end of which is attached to the upper structure and the other end of which is oscillatably attached to the lower structure, and one end is oscillated to the upper structure and the other end is oscillated to the lower structure. A damping mechanism for a seismic isolation device, comprising a second elasto-plastic member, which is irremovably attached and is made of an elasto-plastic member, and plastically deforms in a state where the first elasto-plastic member is deformed in an elastic region. 2. A second elasto-plastic member having a columnar shape, one end of which is attached to the upper structure in a non-swingable manner and the other end of which is attached to a lower structure in a non-swayable manner, the second elasto-plastic member comprising: From the elasto-plastic member which is formed around the second elasto-plastic member and has one end attached to the upper structure in a non-swingable manner and the other end attached to the lower structure in a non-swingable manner. A plurality of first elasto-plastic members, wherein the second elasto-plastic member has elasto-plastic characteristics of plastically deforming while the first elasto-plastic member is deformed in an elastic region. Damping mechanism for seismic isolation devices. 3. A second elasto-plastic member comprising an elasto-plastic member, the second elasto-plastic member having a spiral shape, one end of which is attached to the upper structure in a non-swingable manner and the other end of which is attached to a lower structure in a non-swingable manner, and a spiral. And has a length along the axial center longer than that of the second elasto-plastic member, is arranged around the second elasto-plastic member, and one end of which is attached to the upper structure in a non-swingable manner. A plurality of first elasto-plastic members whose ends are non-swingably attached to the lower structure are provided, and the second elasto-plastic member is configured such that the first elasto-plastic member is deformed in an elastic region. A damping mechanism for seismic isolation devices, which has an elasto-plastic characteristic that plastically deforms in a standing state.