JPH08260756A - Base isolation support device of structure - Google Patents

Abstract

PURPOSE: To provide a support device isolating a structure from the horizontal vibration of an earthquake. CONSTITUTION: A fixed magnetic plate 5a is fixed horizontally by a support frame 5 on the ground 9, and a magnetic plate 4 for floating is provided horizontally at the lower side of the fixed magnetic plate 5a through a clearance by a rigid combining member 6 unitary with a structure 1. An electromagnet 3 is provided between a part of the fixed magnetic plate 5a and the opposing part of the magnetic plate 4 for floating, so as to form a vertical magnetic field with no horizontal component. By the absorbing force in the vertical direction of both electric plates 4 and 5a depending on the vertical magnetic field, the structure 1 is floated and supported, and the structure 1 is cut off from the horizontal vibration of the ground 9. Preferably, the electromagnet 3 is fixed to the magnetic plate 4 for floating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation support system for a structure, and more particularly to a seismic isolation support system for reducing the input seismic motion level to a building having seismic motion input and reducing the response of the building.

[0002]

2. Description of the Related Art In order to secure the safety, reliability and durability of a structure such as a building against horizontal vibration of an earthquake, the structure is supported by a laminated rubber having a low horizontal rigidity, and the low horizontal rigidity is utilized. The primary natural period of a structure is lengthened to obtain a seismic isolation effect for low-frequency input ground motion. The longer period of the primary natural vibration not only enhances the degree of freedom in design, but also reduces the vibration of the building and contributes to the improvement of comfort.

[0003]

However, in the conventional seismic isolation structure, since the weight of the structure is supported by the laminated rubber, the supporting load per laminated rubber is limited, and therefore the horizontal rigidity is also limited. It was common to set the primary natural period of a seismic structure to a maximum of 2 to 3 seconds (frequency 0.33 to 0.5 Hz).

On the other hand, on soft ground such as the waterfront, seismic motion including a long period component longer than 3 seconds has been experienced. In order to obtain an effective seismic isolation effect for a structure on such soft ground, it is desired to further lengthen the natural vibration period of the entire structure including the seismic isolation device. With the current laminated rubber application technology, it is difficult to take appropriate measures because the horizontal rigidity of the laminated rubber is limited as described above in order to withstand the supporting load.

Accordingly, it is an object of the present invention to provide a support device for isolating a structure against horizontal vibration of an earthquake.

[0006]

Referring to FIG. 1 showing an embodiment, a seismic isolation support system for a structure according to the present invention comprises a fixed magnetic plate 5a fixed horizontally by a support frame 5 on a ground 9, a structure. 1. A levitation magnetic plate 4 horizontally arranged below the fixed magnetic plate 5a with a gap by a rigid coupling member 6 integrated with 1 and a horizontal portion between a part of the fixed magnetic plate 5a and a facing portion of the levitation magnetic plate 4 It comprises an electromagnet 3 arranged between both magnetic plates 4 and 5a so as to form a vertical magnetic field Bh (see FIG. 3) having no component. The structure 1 is levitated and supported by the vertical attractive force F (see FIG. 3) between the magnetic plates 4 and 5a based on the vertical magnetic field Bh, and the structure 1 is isolated from horizontal vibration of the ground. Preferably, the electromagnet 3 is fixed to the levitation magnetic plate 4. FIG.
In the above example, the magnetic plates 4, 5a, the support frame 5, the rigid coupling member 6, and the electromagnet 3 are assembled together into the electromagnetic support mechanism 2, and a partially cutaway perspective view thereof is shown in FIG.

In order to reduce the horizontal vibration of the structure 1 due to the wind pressure in the horizontal direction and the seismic horizontal vibration input to the structure 1 from the ground 9 for some reason, the horizontal actuator 13 is constructed as shown in FIG. It may be attached between the object 1 and the ground 9.

[0008]

Referring to the embodiment of the electromagnetic support mechanism 2 shown in FIGS. 1 and 3, the support frame 5 on the ground 9 holds the fixed magnetic plate 5a horizontally. The rigid coupling member 6 integrated with the structure 1 is made of a non-magnetic material, and its lower end penetrates the fixed magnetic plate 5a and extends downwardly, and the levitation magnetic plate 4 is spaced below the fixed magnetic plate 5a. Hold it horizontally. The electromagnet 3 includes annular magnetic core pairs 3a and 3b fixed concentrically to the levitation magnetic plate 4 and its magnetic core pair 3
It consists of a coil 17 wound between a and 3b. Ring core pair 3
The end faces of a and 3b are supported horizontally. However, this electromagnet 3
Is sufficient if it is arranged between both magnetic plates 4 and 5a so as to form a vertical magnetic field Bh with no horizontal component between a part of the fixed magnetic plate 5a and the facing part of the levitation magnetic plate 4, The structure is not limited to the illustrated example. In the case of the structure shown in FIG. 3, the magnetic flux Bh generated by the magnetomotive force of the coil 17 passes through the magnetic core 3a downward, for example, and reaches one magnetic plate, that is, the levitation magnetic plate 4 in this case. Through the magnetic core 3b and the air gap between the magnetic core 3b and the magnetic plate 5a to reach the other magnetic plate, the fixed magnetic plate 5a in this case, and the other magnetic plate 5a and the magnetic plate 5a
It passes through the closed magnetic circuit which returns to the first magnetic core 3a via the gap between 3a.

Both magnetic plates 4 and 5a are horizontal and the magnetic core 3a,
Since the end face of 3b is horizontal, the magnetic core 3b / magnetic plate in this case
This magnetic flux Bh in the gap between the magnetic plates 4 and 5a, which is composed of the gap between 5a and the gap between the magnetic plate 5a and the magnetic core 3a, can be made vertical without a horizontal component. Also, this vertical magnetic flux
Since Bh is formed between a part of the fixed magnetic plate 5a and a facing part of the levitation magnetic plate 4, even if the levitation magnetic plate 4 moves relative to the fixed magnetic plate 5a on the same horizontal plane. Even after the movement process and after the movement, the fixed magnetic plate 5a
The same vertical magnetic flux Bh is maintained between a part of the above and the facing part of the levitation magnetic plate 4. Moreover, since there is no horizontal component in the vertical magnetic flux Bh, the levitation magnetic plate 4 is not only when the levitation magnetic plate 4 is stationary, but also when the levitation magnetic plate 4 is moving relative to the fixed magnetic plate 5a in the same horizontal plane. No horizontal coupling force is generated between the fixed magnetic plate 5a and the fixed magnetic plate 5a.

That is, in FIG. 1, even if the ground 9 moves or vibrates horizontally relative to the structure 1 due to horizontal seismic motion or the like, the motion or vibration is levitated by the electromagnetic support mechanism 2. Nothing is transmitted to 1.

Therefore, the object of the present invention is to provide the "supporting device for isolating the structure against the horizontal vibration of an earthquake".

Although there is an example in which the structure 1 is levitated from the ground 9 by an electromagnetic force, conventionally, an electromagnetic repulsive force is used, and the repulsive force always has a horizontal component and causes horizontal vibration of the ground 9 to occur in the structure. Therefore, the conventional method using the repulsive force cannot isolate the structure 1 from the horizontal vibration of the earthquake as in the present invention.

[0013]

FIG. 4 shows another embodiment of the electromagnetic support mechanism 2. In the electromagnetic support mechanism 2 of this embodiment, the rigid coupling member 6 fixed to the structure 1 has a hollow portion, and the levitation magnetic plate 4 and the electromagnet 3 are horizontally held on the lower surface of the hollow portion.
The upper end of the support frame 5 fixed to the ground 9 penetrates the levitation magnetic plate 4 and extends above it, and holds the fixed magnetic plate 5a above the levitation magnetic plate 4 horizontally with a gap.

Referring to FIG. 7, the structure 1 has a floor area of 600 m.
^{In the case of a two} -story office building with a reinforced concrete structure with an estimated total weight of 3600 tons in ² above, each of them has a magnetic attraction force of 30
The seismic isolation support device of the present invention can be constructed by using twelve electromagnetic support mechanisms 2 capable of raising 0 tons. Considering the magnetic flux density required for the generation of this attractive force, the current, the cooling method, etc., the electromagnet 3 of the electromagnetic support mechanism 2 in FIG. 7 is a superconducting device.

An example of a control circuit for maintaining the structure 1 in a floating state is shown in FIG. In order to maintain the lifting force of the electromagnetic support mechanism 2, it is necessary to maintain the vertical magnetic flux Bh between the levitation magnetic plate 4 and the fixed magnetic plate 5a. The size of the air gap between the fixed magnetic plate 5a and the magnetic resistance of the air gap must be kept constant. In the illustrated example, the gap G between the inner bottom surface of the support frame 5 and the bottom surface of the levitation magnetic plate 4 is monitored by the displacement sensor 7,
By keeping this gap G constant, the size of the gap between the electromagnet 3 fixed to the levitation magnetic plate 4 and the fixed magnetic plate 5a and the vertical magnetic flux Bh in the gap are controlled to a predetermined value.
In the control, the output of the displacement sensor 7 is applied to the control device 8, the power supply 15 is operated by the operation output of the control device 8, and the current of the electromagnet 3 is adjusted so that the interval G is maintained at the set value.

In order to reduce the horizontal vibration of the structure 1 due to the horizontal wind pressure and to reduce the horizontal vibration input from the ground 9 to the structure 1 due to the leakage flux of the vertical magnetic field Bh and other causes, as shown in FIG. The horizontal actuator 13 may be mounted between the structure 1 and the ground 9. The actuator 13 in the illustrated example is of a hydraulic type, and the structure 1
A horizontal control force corresponding to a horizontal input to the actuator 13 is generated by the actuator 13, and the control force can be applied to the structure 1 to further improve the seismic isolation effect.

FIG. 5 shows an embodiment in which the laminated rubber 10 suppresses horizontal vibration. In this case, the laminated rubber 10 does not need to support the weight of the structure 1, and the horizontal elastic characteristics can be arbitrarily selected. As a result, the period of apparent horizontal natural vibration of the structure 1 supported by the seismic isolation support device of the present invention is conventionally 2-3 seconds to 4 seconds or more, preferably 10 seconds.
It is possible to further lengthen the period by setting the time to be more than a second. Further, a hydraulic damper 11 may be added to quickly suppress the residual vibration after the earthquake. Fig. 7 assumes a five-story office building, and uses a seismic isolation support device for the electromagnetic support mechanism 2,
An example of the arrangement of the constituent devices when the laminated rubber 10 and the hydraulic damper are used is shown.

FIG. 6 shows an embodiment in which the horizontal rigidity is added by a repulsive electromagnet 12 instead of the laminated rubber 10. In this case, the strength of the repulsive force of the electromagnet 12 is changed by selecting the magnitude of the excitation current of the electromagnet 12 to arbitrarily set the apparent rigidity of the structure 1, and hence the period of its horizontal natural vibration. You can Further, by actively controlling the repulsive force of the electromagnet 12 according to the magnitude of the horizontal displacement of the structure 1, a better seismic isolation effect can be exhibited.

[0019]

As described in detail above, the seismic isolation support system for a structure of the present invention isolates the structure from horizontal vibration of the ground by levitating the structure by the attractive force of the electromagnet. Has a remarkable effect.

(B) The structure can be isolated from the seismic motion in the horizontal direction to form a seismic isolated structure. (B) Since the structure is levitated by the vertical suction force with no horizontal component, the horizontal vibration characteristics (natural period, damping) of the structure can be arbitrarily set by various means such as hydraulic pressure, electromagnetic force, or elastic force of rubber. Can be set to. (C) It is expected that the magnetic levitation will achieve the seismic isolation effect for the long-period component of an earthquake on soft ground such as the waterfront, which was difficult in the past.

[Brief description of drawings]

FIG. 1 shows an embodiment of a seismic isolation support system for structures according to the present invention.

FIG. 2 is an explanatory diagram of an example of a control circuit of an electromagnetic support mechanism.

FIG. 3 is a partially cutaway perspective view of an example of the structure of an electromagnetic support mechanism.

FIG. 4 is an explanatory diagram of another example of the structure of the electromagnetic support mechanism.

FIG. 5 is an explanatory diagram of a seismic isolation support device including laminated rubber.

FIG. 6 is an explanatory view of a seismic isolation support device including a horizontal repulsion-type electromagnet.

FIG. 7 is an explanatory diagram of an example of a seismic isolation support device for a building.

[Explanation of symbols]

 1 Structure 2 Electromagnetic support mechanism 3 Electromagnets 3a, 3b Magnetic core 4 Levitation magnetic plate 5 Support frame 5a Fixed magnetic plate 6 Rigid coupling member 7 Displacement sensor 8 Controller 9 Ground 10 Laminated rubber 11 Hydraulic damper 12 Repulsive electromagnet 13 Horizontal Directional actuator 15 Power supply 17 coil.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsura Ogasawara 2-1-1 Hibita, Chofu City, Tokyo Kashima Construction Co., Ltd.

Claims (10)

[Claims] 1. A fixed magnetic plate horizontally fixed by a support frame on the ground, a levitation magnetic plate horizontally arranged below the fixed magnetic plate by a rigid connecting member integrated with a structure with a gap, and A structure is provided by an electromagnet arranged between both magnetic plates so as to form a vertical magnetic field without a horizontal component between a part of the fixed magnetic plate and a facing part of the levitation magnetic plate, and a structure due to a vertical attractive force based on the vertical magnetic field. A seismic isolation support device for a structure that floats and supports the structure to isolate the structure from horizontal vibration of the ground. 2. The seismic isolation support system according to claim 1, wherein the electromagnet is fixed to the levitation magnetic plate, a gap is provided between the electromagnet and the fixed magnetic plate, and the structure is formed by the vertical magnetic flux in the gap. A seismic isolation support device for a structure in which an object is levitated. 3. The seismic isolation support device according to claim 1,
A seismic isolation support device for a structure, in which a horizontal actuator is attached between the structure and the ground, and a damping force corresponding to horizontal vibration of the structure with respect to the ground is applied from the horizontal actuator to the structure. 4. The seismic isolation support device according to claim 3, wherein the horizontal actuator is a laminated rubber in which the horizontal actuator is coupled to the structure and the ground. 5. The seismic isolation support system according to claim 3, wherein the horizontal actuator is a hydraulic actuator or a hydraulic damper in which the horizontal actuator is coupled to the structure and the ground. 6. The seismic isolation support device according to claim 3, wherein the horizontal actuator is a repulsive electromagnet in which the horizontal actuator is connected to the structure and the ground. 7. The seismic isolation support system according to claim 1, 2 or 3, wherein the structure is a building. 8. The seismic isolation support system according to claim 7, wherein the apparent horizontal period of the building is made longer than 4 seconds by the horizontal actuator. 9. The seismic isolation support system of claim 7, wherein the electromagnet is a superconducting magnet. 10. The seismic isolation support system according to claim 2, wherein a distance sensor for detecting a distance between the electromagnet and the fixed magnetic plate, and a controller for adjusting a current of the electromagnet according to an output of the distance sensor. A seismic isolation support device for structures.