JP7019487B2 - Seismic isolation structure - Google Patents

Description

The present invention relates to a seismic isolation structure.

When resonance occurs due to the action of seismic motion, a large response occurs in the structure. For this reason, in the past, in buildings (structures) such as condominiums and office buildings, vibration damping dampers were installed inside the buildings, and the vibration damping dampers absorbed and attenuated the seismic energy (vibration energy) that acted during an earthquake. I am trying to reduce the response of. In addition, such vibration damping dampers include history dampers that utilize the yield resistance of steel materials and the frictional resistance of slip materials, viscous dampers such as oil dampers that utilize the viscous resistance of viscoelastic materials, and shearing of viscoelastic materials. Viscoelastic dampers that utilize resistance are often used.

In addition, as another means for reducing the earthquake response of the building, it has been proposed and put into practical use to install a vibration damping device called TMD (Tuned Mass Damper) on the top side of the building (rooftop, etc.) ( For example, see Patent Document 1 and Patent Document 2).

Further, a method of reducing the response by installing a seismic isolation device and shifting the primary natural period of a structure such as a building to the long period side is often used (see, for example, Patent Document 3).

Furthermore, it is equipped with a rotational inertia mass device and a hardening type restoring force device (variable rigidity device) whose rigidity changes according to displacement, making it possible to effectively avoid the resonance phenomenon due to the input of periodic vibration energy. Some are (see, for example, Patent Document 4 and Patent Document 5).

On the other hand, in Patent Document 4 and Patent Document 5, complicated non-linearity is assumed in the curable restoring force device and the rotational inertia mass device, but there is a published paper as an example of a simpler study (non-patent document). 1).

Here, as a characteristic of a general seismic waveform, it is often the case that the first major motion has a large acceleration containing many short-period components, and then the acceleration itself is small but contains many long-period components.

For example, FIG. 1 is an observation record of the 2011 off the Pacific coast of Tohoku Earthquake in Otemachi, Chiyoda-ku, Tokyo. Since the main motion (R1) with large acceleration arrives first, and then the wave containing many long-period components arrives, a long-time back sway (R2) can be confirmed when looking at the displacement component.

Japanese Unexamined Patent Publication No. 2000-18323 Japanese Unexamined Patent Publication No. 2011-22511 Japanese Unexamined Patent Publication No. 2010-0709009 Japanese Unexamined Patent Publication No. 2017-3089 Japanese Unexamined Patent Publication No. 2017-3090

Koichi Watanabe, "Analytical Study on Vibration Control Using Curing Restoring Force Characteristics (http://opac.ll.chiba-u.jp/da/curator/101951/TLA_0227.pdf)", Chiba University Degree Thesis, January 2016

In the above-mentioned Patent Document 4, Patent Document 5, Non-Patent Document 1, etc., a) The seismic isolation structure is further lengthened by the additional mass effect of the rotational inertia mass device, and the input energy of the short-period component of the main motion is the building. B) The hardening type restoring force device prevents resonance during backswing, and c) Furthermore, the hardening type restoring force device suppresses the increase in displacement and is expected to have the effect of preventing the building from colliding with the retaining wall. can.

However, since the hardening type restoring force device is not very effective until the displacement increases, an expansion joint that allows a certain degree of relative displacement between the building and the ground is required. In other words, there was the inconvenience that the expansion joint had to be configured to accommodate the relative displacement between the building and the ground until the curable restoring force device became effective.

In view of the above circumstances, the present invention more effectively and reliably a) further lengthens the seismic isolation structure by the additional mass effect of the rotational inertia mass device, and the input energy of the short-period component of the main motion is transmitted to the building. The seismic isolation that made it possible to prevent the building from colliding with the retaining wall by b) preventing resonance during backswing with a hardening type restoring force device and c) suppressing an increase in displacement with a hardening type restoring force device. The purpose is to provide seismic structures.

In order to achieve the above object, the present invention provides the following means.

The seismic isolation structure of the present invention includes a seismic isolation pit, an underground structure portion provided in the internal space of the seismic isolation pit, and a building body provided on the underground structure portion, and has a bottom surface of the seismic isolation pit. The underground structure is supported by a seismic isolation device interposed in the seismic isolation layer between the lower surface of the underground structure and the seismic isolation layer between the upper surface of the underground structure and the lower surface of the building body. The building body is supported by an intervening seismic isolation device, and a rotary inertial mass device is provided by connecting one end to the underground structure and the other end to the seismic isolation pit, and the rigidity changes according to the displacement. A hardening type restoring force device is provided by connecting one end to the underground structure portion and the other end to the seismic isolation pit, and a first hydraulic jack is provided between the underground structure portion and the seismic isolation pit. A second hydraulic jack is provided between the underground structure portion and the building body, and the oil chambers of the first hydraulic jack and the second hydraulic jack are connected to each other by a connecting pipe to connect the underground structure portion and the ground. When the relative displacement of the above becomes equal to or more than a predetermined value, the operation of the first hydraulic jack and the second hydraulic jack is started, and the first hydraulic jack and the second hydraulic jack move the underground structure portion and the building body. It is characterized in that it is configured to exert an action force in the opposite direction.

It is a figure which shows the observation record in Otemachi, Chiyoda-ku, Tokyo of the 2011 off the Pacific coast of Tohoku Earthquake. It is a figure which shows an example of the seismic isolation structure which concerns on one Embodiment of this invention. It is a figure which shows the modification example of the seismic isolation structure which concerns on one Embodiment of this invention. It is a figure which shows an example of the displacement of the underground structure of the seismic isolation structure which concerns on one Embodiment of this invention, the displacement of a building body, and the operational displacement of a hydraulic jack.

Hereinafter, the seismic isolation structure according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4.

As shown in FIG. 2, the seismic isolation structure A of the present embodiment includes a concrete seismic isolation pit 1 formed by excavating the ground G and an underground structure portion 2 provided in the internal space of the seismic isolation pit 1. , The building main body 3 provided on the underground structure portion 2 is provided.

The underground structure portion 2 is provided with a recess 2a recessed from the upper surface to the lower surface side, and the building body 3 is provided above the underground structure portion 2 so that the lower end portion side is inserted and arranged in the recess 2a. .. Further, the building body 3 projects laterally from the side surface, overlaps the outer portion of the recess 2a of the underground structure portion 2 vertically, and has an upper surface substantially flush with the ground surface outside the seismic isolation pit 1. It is configured to include a surface portion (overhanging portion) 3a.

The ground surface portion (overhanging portion) 3a is arranged so as to cover the internal space of the seismic isolation pit 1, and the tip portion in the protruding direction is a predetermined gap between the side wall portion (retaining wall) 1a of the seismic isolation pit 1. Is arranged so as to face the side wall portion 1a. The ground surface portion 3a and the side wall portion 1a of the seismic isolation pit 1 are connected by an expansion joint 4 arranged so as to cover the gap, and the inside of the seismic isolation pit 1 is connected by the expansion joint 4 and the ground surface portion 3a. The space is closed.

A plurality of seismic isolation devices 6 such as laminated rubber are interposed in the first seismic isolation layer 5 between the lower surface of the underground structure portion 2 and the bottom surface of the seismic isolation pit 1, and the underground structure portion 2 is the plurality of seismic isolation devices. Supported by 6. The first seismic isolation layer 5 is provided with a rotary inertial mass device 7 having one end connected to the underground structure portion 2 and the other end connected to the seismic isolation pit 1. As the rotary inertial mass device 7, a conventionally known one can be applied.

A gap having a predetermined size is provided between the underground structure portion 2 and the side wall portion 1a of the seismic isolation pit 1. In the gap between the underground structure 2 and the side wall 1a of the seismic isolation pit 1, one end is connected to the underground structure 2 and the other end is connected to the side wall 1a of the seismic isolation pit 1, and the axial direction is horizontal. A curing type restoring force device (variable rigidity device) 8 arranged in the horizontal direction is provided. The curing type restoring force device 8 is a device whose rigidity changes according to displacement, and the above-mentioned variable rigidity device of Patent Document 4, the curing type restoring force device of Non-Patent Document 1, and the like can be applied.

Further, a gap between the underground structure portion 2 and one side wall portion of the seismic isolation pit 1 and a gap between the underground structure portion 2 and the one side wall portion 1a of the seismic isolation pit 1 and the other side wall portion 1a facing the seismic isolation pit 1. Each is provided with a first hydraulic jack (hydraulic cylinder) 9 having one end connected to the underground structure portion 2 and arranged with the axial direction oriented in the horizontal lateral direction. Further, these first hydraulic jacks 9 are provided with a predetermined space between the other end and the side wall portion 1a of the seismic isolation pit 1, and the underground structure portion 2 periodically rolls during an earthquake. When a displacement of a predetermined amount or more occurs, the other end abuts on the side wall portion 1a of the seismic isolation pit 1, and the hydraulic jack force acts on the underground structure portion 2.

A plurality of seismic isolation devices 6 such as laminated rubber are interposed in the second seismic isolation layer 10 between the bottom surface of the recess 2a of the underground structure portion 2 and the lower surface of the building body 3, and the building body 3 has these plurality of seismic isolation devices. Supported by device 6. Further, a plurality of seismic isolation devices 6 such as laminated rubber are interposed in the third seismic isolation layer 11 between the upper surface of the portion other than the recess 2a of the underground structure portion 2 and the lower surface of the ground surface portion 3a of the building body 3. The building body 3 is also supported by these plurality of seismic isolation devices 6.

A gap is provided between the inner surface of the recess 2a of the underground structure 2 and the side surface of the building body 3. Between one inner surface of the recess 2a of the underground structure 2 and the side surface of the building body 3 and between the other inner surface facing one inner surface of the recess 2a of the underground structure 2 and the side surface of the building body 3. A second hydraulic jack (hydraulic cylinder) 12 is provided with one end connected to the underground structure 2 and the other end connected to the building body 3 and the axial direction is arranged in the horizontal horizontal direction. ..

In the seismic isolation structure A of the present embodiment, the first hydraulic jack 9 between the underground structure portion 2 and the seismic isolation pit 1 and the second hydraulic jack 12 between the underground structure portion 2 and the building body 3 are used. Are connected by a connecting pipe 13 so as to transmit hydraulic pressure to each other. Specifically, the first hydraulic jack 9 between the underground structure 2 and the seismic isolation pit 1 and the second hydraulic jack 12 between the underground structure 2 and the building body 3 are the underground structure 2 and the ground G. The operation is started when the relative displacement becomes more than a certain level, and at this time, the first hydraulic jacks 9 and 12 exert an acting force that reverses the movements of the underground structure portion 2 and the building body 3. The oil chambers of 9 and the second hydraulic jack 12 are connected to each other by a connecting pipe 13.

Here, the seismic isolation device 6 provided in the first seismic isolation layer 5, the second seismic isolation layer 10, and the third seismic isolation layer 11 may be a sliding bearing or the like in addition to the laminated rubber, and is particularly limited. Do not.

Further, as shown in FIG. 3, if the first hydraulic jack 9 is provided between the underground structure portion 2 and the seismic isolation pit 1, the second hydraulic jack 12 is located between the underground structure portion 2 and the building body 3. If it is provided, there is no need to further limit the arrangement. Further, the number of the first hydraulic jack 9 and the second hydraulic jack 12 does not need to be limited.

When an earthquake occurs, the ground G violently shakes in a short cycle in the main motion R1 as shown in FIG. 1. However, in the seismic isolation structure A of the present embodiment having the above configuration, laminated rubber or the like is exempted. Since the period is extended by the seismic isolation device 6 and the rotational inertia mass device 7, the input energy to the underground structure portion 2 is reduced.

When the value of the virtual mass of the rotary inertial mass device 7 is made extremely large, the effect of the rotary inertial mass device 7 as a high-pass filter (which allows short-period components to pass through as it is) becomes remarkable. It is desirable that the ratio of virtual mass is about 1 or less at the maximum.

In addition, some short-period components input to the underground structure 2 due to the influence of the rotary inertia mass device 7 are seismic isolated such as laminated rubber of the second stage (second seismic isolation layer 10, third seismic isolation layer 11). Since it is blocked by the device 6, it is not transmitted to the building body 3 very much.

As a result, according to the seismic isolation structure A of the present embodiment, it is possible to suitably suppress the shaking of the building body 3.

Here, in a situation where the building body 3 does not shake at all, that is, in a situation where it is stationary in the absolute coordinate system, the maximum value of the displacement component of the shaking of the ground G is the displacement to be considered in the expansion joint 4. It has been confirmed that the displacement to be considered is, for example, about 10 cm at the maximum in the present embodiment, which is considerably smaller than the relative displacement assumed in the normal seismic isolation structure.

Next, as shown in FIG. 1, after the main motion R1, the acceleration becomes small, but the displacement component becomes conspicuous. That is, the long-period component that becomes the input energy to the seismic isolation structure A is predominant. Assuming that the building body 3 is stationary on the absolute coordinate system, the maximum displacement of the ground G is the displacement to be considered in the expansion joint 4, and the displacement of the backswing R2 after the main motion R1 is not so large.

Therefore, what is worrisome as the expansion joint 4 is the increase in displacement due to the resonance of the seismic isolation structure A.

In the existing technique, resonance is suppressed by arranging the curing type restoring force device 8. Further, in the vicinity of the target upper limit value determined so as not to hit the side wall portion 1a of the seismic isolation pit 1, the rigidity of the curing type restoring force device 8 rapidly increases and the displacement is suppressed.

On the other hand, in the seismic isolation structure A of the present embodiment, when the hydraulic jack operating displacement determined in consideration of the performance of the expansion joint 4 is reached, the underground structure portion 2 and the building body 3 are moved in different directions. The hydraulic jacks 9 and 12 are activated. As a result, as the displacement of the underground structure portion 2 increases, the displacement of the building body 3 can be reduced.

By changing the diameters of the two hydraulic jacks 9 and 12, it is possible to adjust the influence of the displacement of the underground structure portion 2 on the displacement of the building body 3.

Therefore, according to the seismic isolation structure A of the present embodiment, a) the seismic isolation structure A is further lengthened by the additional mass effect of the rotational inertia mass device 7 to shorten the main motion R1. The input energy of the periodic component is not transmitted to the building, b) the hardening type restoring force device 8 prevents resonance at the time of back shaking, and c) the hardening type restoring force device 8 further suppresses the increase in displacement and the retaining wall (isolation). It becomes possible to prevent the building 3 from colliding with the side wall portion 1a) of the seismic isolation pit 1.

Although the embodiment of the seismic isolation structure A according to the present invention has been described above, the present invention is not limited to the above-mentioned embodiment and can be appropriately modified without departing from the spirit of the present invention.

1 Seismic isolation pit 1a Side wall (retaining wall)
2 Underground structure 2a Recess 3 Building body 3a Ground surface (overhanging part)
4 Expansion joint 5 1st seismic isolation layer 6 Seismic isolation device 7 Rotating inertial mass device 8 Hardened restoring force device 9 1st hydraulic jack 10 2nd seismic isolation layer 11 3rd seismic isolation layer 12 2nd hydraulic jack 13 Connecting pipe A Seismic isolation structure

Claims (1)

It is provided with a seismic isolation pit, an underground structure provided in the internal space of the seismic isolation pit, and a building body provided on the underground structure.
The underground structure is supported by a seismic isolation device interposed in the seismic isolation layer between the bottom surface of the seismic isolation pit and the lower surface of the underground structure.
The building body is supported by a seismic isolation device interposed in a seismic isolation layer between the upper surface of the underground structure portion and the lower surface of the building body.
A rotary inertial mass device is provided by connecting one end to the underground structure and the other end to the seismic isolation pit, and a hardening type restoring force device whose rigidity changes according to displacement is provided by connecting one end to the underground structure. The other end is connected to the seismic isolation pit and provided.
Further, a first hydraulic jack is provided between the underground structure portion and the seismic isolation pit, and a second hydraulic jack is provided between the underground structure portion and the building body.
The oil chambers of the first hydraulic jack and the second hydraulic jack are connected to each other by a connecting pipe, and the relative displacement between the underground structure and the ground becomes equal to or more than a predetermined value, and the first hydraulic jack and the second hydraulic pressure are used. The operation of the jack is started, and the first hydraulic jack and the second hydraulic jack are configured to exert an action force that reverses the movements of the underground structure portion and the building body. Seismic structure.

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