JP7841911B2 - Vibration isolation and damping composite system - Google Patents

Description

This invention relates to a vibration isolation and damping composite system.

Conventionally, inclined sliding bearings, where the sliding surface of the sliding bearing is an inclined surface, have been known. They consist of two guide rails (an upper guide section and a lower guide section made of steel) that intersect at right angles, and a slider that slides along the friction surface while connecting them. Friction material is provided on the upper and lower surfaces of the slider to contact the inclined surface. The frictional resistance force generated when the slider slides along the friction surface acts as a damping force, and the weight of the structure acts on the inclined friction surface to obtain a restoring force.

Furthermore, vibration experiments have confirmed that residual displacement can be almost eliminated by setting the relationship between the friction coefficient μ of the friction material and the inclination angle θ to approximately tanθ = (0.1 to 0.4)μ, and this has already been implemented in projects for seismic isolation of automated rack warehouses (see Patent Document 1 below).

However, when inclined sliding bearings are applied to tall, flexible structures where bending deformation is dominant, the acceleration at the upper end of the structure can become large due to the influence of higher-order modes. To address this problem, a technology combining inclined sliding isolation and TMD (Temporal Mass Diode) has been proposed (see Patent Document 1 below).

Patent No. 5850231 Patent No. 6804738

However, in structures with suspension systems, such as elevators, the periods of the superstructure and the suspension system are not the same, resulting in separate movements. Therefore, the effectiveness of reducing acceleration at the top of the superstructure by using both inclined sliding bearings and upper TMDs may be diminished.

Therefore, the present invention has been made in view of the above circumstances, and provides a vibration isolation and damping composite system that can reduce the acceleration of both the superstructure and the suspension structure during an earthquake.

To achieve the above objective, the present invention employs the following means.
In other words, the vibration isolation and damping composite system according to the present invention is a vibration isolation and damping composite system installed in a building comprising a superstructure and a suspended structure suspended from the superstructure, comprising: an upper vibration damping device provided at the top of the superstructure and functioning as a TMD; a sliding bearing supporting the lower part of the superstructure; and a lower vibration damping device provided at the bottom of the suspended structure and functioning as a TMD.

In this type of seismic isolation and damping composite system, an upper damping device functioning as a TMD is installed at the top of the superstructure, and a lower damping device functioning as a TMD is installed at the bottom of the suspended structure. Since the sliding bearings supporting the lower part of the superstructure do not have a natural period, the synchronization period of the TMD mechanism can be set to the primary period of the structure in a non-seismic-isolated state (with the seismic isolation layer fixed), without being affected by the rigidity of the sliding bearings, making it easier to determine the TMD specifications. This reduces the influence of the characteristics of the input seismic waves and prevents resonance with the seismic waves. During an earthquake, both acceleration at locations above the structural center of gravity, such as the superstructure, and acceleration at locations below the center of gravity, such as the suspended structure, can be reduced.

Furthermore, in the vibration isolation and damping composite system according to the present invention, the mass of the upper vibration damping device may be 7% to 9% of the effective mass of the superstructure.

In this type of vibration isolation and damping composite system, the acceleration of the superstructure and suspension structure can be reliably reduced.

Furthermore, in the vibration isolation and damping composite system according to the present invention, the mass of the lower vibration damping device may be 10% to 20% of the effective mass of the suspension structure.

In this type of vibration isolation and damping composite system, the acceleration of the superstructure and suspension structure can be reliably reduced.

According to the seismic isolation and damping composite system of the present invention, the acceleration of both the superstructure and the suspended structure can be reduced during an earthquake.

This is a schematic diagram showing a vibration isolation and damping composite system according to one embodiment of the present invention. This is a schematic diagram illustrating a seismic damping device according to one embodiment of the present invention. This diagram illustrates the method for calculating the first period and effective mass. (a) is an exploded perspective view of the slider of a sliding bearing in one embodiment of the present invention, and (b) is an exploded perspective view of the sliding bearing. (a) is a plan view of a sliding bearing according to one embodiment of the present invention, (b) is a cross-sectional view of (a) along the line b-b, and (b) is a cross-sectional view of (a) along the line c-c. This figure shows the normal state of a sliding bearing according to one embodiment of the present invention. This figure shows the state of a sliding bearing in one embodiment of the present invention during an earthquake. This is a diagram showing the analysis model. This figure shows the waveforms of seismic waves used for analysis, with (a) El Centro, (b) Taft, and (c) Hachinohe. The analysis results show the acceleration at the top of the superstructure, with (a) El Centro, (b) Taft, and (c) Hachinohe. The analysis results show the acceleration at the lowest point of the suspended structure, with (a) El Centro, (b) Taft, and (c) Hachinohe. The analysis results show seismic isolation displacement, with (a) El Centro, (b) Taft, and (c) Hachinohe.

A vibration isolation and damping composite system according to one embodiment of the present invention will be described with reference to the drawings.
Figure 1 is a schematic diagram showing a vibration isolation and damping composite system according to one embodiment of the present invention.
As shown in Figure 1, the seismic isolation and damping composite system 2 according to this embodiment is installed in building 1. Building 1 comprises a pit 10, a superstructure 17, and a suspension structure 19.

The pit 10 comprises a base plate 11 and a peripheral wall 12 erected from the outer edge of the base plate 11. An outward-projecting overhang 12a is provided at the upper end of the peripheral wall 12. Inside the pit 10, a storage space 10s capable of accommodating a suspension structure is formed.

The superstructure 17 comprises a beam 15 and a building body 16. The beam 15 supports the building body 16. The beam 15 is positioned above the overhang 12a. In plan view, the beam 15 is positioned along the extending direction of the overhang 12a. The outer edge of the lower end of the building body 16 is supported by the beam 15. For example, the building body 16 is formed from multiple layers.

The upper end 19u of the suspension structure 19 is supported by the lower end 17d of the superstructure 17. The suspension structure 19 is suspended from the lower end 17d of the superstructure 17 and housed in the accommodating space 10s of the pit 10. The suspension structure 19 is positioned at a distance from the surrounding wall 12 of the pit 10. The suspension structure 19 is, for example, an elevator.

The vibration isolation and damping composite system 2 comprises an upper vibration damping device 20A, a lower vibration damping device 20B, and a sliding bearing 30.

The upper vibration damping device 20A is installed at the uppermost part 17u of the superstructure 17. A support plate, such as a concrete slab, is provided at the lowest part 19d of the suspension structure 19. The lower vibration damping device 20B is installed at the lowest part 19d of the suspension structure 19.

The upper vibration damping device 20A and the lower vibration damping device 20B are collectively referred to as the vibration damping device 20. The vibration damping device 20 functions as a TMD (Tuned Mass Damper). The installation surface on which the vibration damping device 20 is installed is referred to as the installation surface 20a. For the upper vibration damping device 20A, the installation surface 20a is the uppermost part 17u of the upper structure 17, and for the lower vibration damping device 20B, it is the lowermost part 19d of the suspension structure 19.

Figure 2 is a schematic diagram illustrating the vibration damping device 20.
As shown in Figure 2, the vibration damping device 20 includes a fixed part 21, a movable mass 22, a damping part 23, another damping part 23, and a horizontal spring 24.

The fixing part 21 is fixed to the installation surface 20a. The fixing part 21 is fixed so as not to displace relative to the installation surface 20a. The fixing part 21 has a slider 21a that supports the movable mass 22 so as to be movable in the horizontal direction.

The movable mass 22 is supported by the fixed part 21 and is movable relative to the fixed part 21 in the horizontal direction.

The damping section 23 is positioned between the fixed section 21 and the movable mass 22, and dampens the relative vibration of the movable mass 22 relative to the fixed section 21 while allowing this relative vibration. The damping section 23 is composed of a damping device using an oil damper or viscoelastic rubber, and in this embodiment, the damping constant h is set to approximately 10%.

The horizontal spring 24 is positioned in parallel with the damping unit 23 between the fixed part 21 and the movable mass 22, biasing the movable mass 22 while allowing relative vibration of the movable mass 22 with respect to the fixed part 21.

Figure 3 illustrates the method for calculating the first period and effective mass.
As shown in Figure 3, with the vibration damping device 20 not functioning as a TMD (no TMD), the joint nodes Q1 and Q2 of the superstructure 17 and the suspension structure 19 are fixed ends. The first period Tu of the superstructure 17 and the first period Td of the suspension structure 19, as well as the effective mass Meu of the superstructure 17 and the effective mass Med of the suspension structure 19 are calculated using eigenvalue analysis.

The movable mass of the upper vibration damping device 20A is preferably about 7% to 9% of the effective mass Meu of the upper structure 17, with 7% being even more preferable. The movable mass of the lower vibration damping device 20B is preferably about 10% to 20% of the effective mass Med of the suspension structure 19, with 10% being even more preferable.

In this embodiment, the sliding bearing 30 is an inclined sliding bearing. The sliding bearing 30 is for supporting the superstructure 17 so that it can slide horizontally in all directions relative to its supporting structure, the pit 10. Multiple sliding bearings 30 are installed.

Figure 4 is (a) an exploded perspective view of the slider 35 of the sliding bearing 30, and (b) an exploded perspective view of the sliding bearing 30.
As shown in Figure 4, the sliding bearing 30 includes an upper guide member 33, a lower guide member 34, and a slider 35. The upper guide member 33 is fixed to the lower part 15d (see Figure 1) of the beam 15 of the superstructure 17. The lower guide member 34 is fixed to the upper part 12u of the overhang 12a of the pit 10. The slider 35 is interposed between the upper guide member 33 and the lower guide member 34. The slider 35 is held so as to be slidable only in one horizontal direction relative to the upper guide member 33 (shown as the X-X direction in Figure 4). The slider 35 is held so as to be slidable only in another horizontal direction perpendicular to the horizontal direction relative to the lower guide member 34 (shown as the Y-Y direction in Figure 4).

Figure 5 is (a) a plan view of the sliding support 30, (b) a cross-sectional view of (a) along the line b-b, and (b) a cross-sectional view of (a) along the line c-c.
The upper guide member 33 and the lower guide member 34 are both identical in shape and size, forming a horizontally elongated block with a rectangular cross-section. The upper guide member 33 and the lower guide member 34 are oriented perpendicular to each other in their longitudinal directions. The upper guide member 33 and the lower guide member 34 are positioned opposite each other with a gap between them in the vertical direction. As shown in Figures 5(b) and (c), in this configuration, the upper guide member 33 is fixed to the upper structure 17, and the lower guide member 34 is fixed to the pit 10.

As shown in Figure 4(b), grooves are formed along the longitudinal direction of the upper guide member 33 and the lower guide member 34 on their opposing surfaces (i.e., the lower surface of the upper guide member 33 and the upper surface of the lower guide member 34). The depth of the grooves gradually decreases from the center toward both sides. The bottom surface of the grooves is a gently sloping V-shape.

The groove of the upper guide member 33 faces downwards, and the direction of the groove's extension is aligned with the X-X direction. The upper guide member 33 is fixed to the upper structure 17. As a result, the bottom surface of the groove formed in the upper guide member 33 becomes a downward-sloping upper inclined surface 36 that gently slopes in an inverted V shape along the X-X direction.

The groove of the lower guide member 34 faces upward, and the direction of the groove's extension is aligned with the Y-Y direction. The lower guide member 34 is fixed to the pit 10. As a result, the bottom surface of the groove formed in the lower guide member 34 becomes an upward-facing lower inclined surface 37 that slopes gently in a V-shape along the Y-Y direction.

Figure 6 shows the sliding bearing 30 in its normal state.
As shown in Figure 6, if W is the axial force (self-weight) supported by the sliding bearing 30, the restoring force (horizontal force) F due to the inclination is expressed by equation (1), where θ is the angle of inclination with respect to the horizontal plane. The contact surface of the slider 35 is the entire upper surface. Hereinafter, μ is the coefficient of friction of the inclined surface, and μW represents the frictional force.

Figure 7 shows the state of the sliding bearing 30 during an earthquake.
As shown in Figure 7, the sliding bearing 30 moves in response to the horizontal displacement that occurs in the seismic isolation layer during an earthquake. The contact surface of the slider 35 is half of the upper surface. Note that the actual slope is 1/100 to 1/20, but the inclination angle θ is shown as large for clarity.

The relationship between the inclination angle θ and the coefficient of friction μ of the inclined surface is expressed by equation (2).

The coefficient of friction μ (tanθ) is assumed to be between 0.1 and 0.4. Furthermore, while the coefficient of friction needs to be adjusted according to the seismic isolation design displacement, the use of low-friction materials ensures that μ ≤ 0.06.

Next, I will explain the analysis results.

<Analysis conditions>
- Analysis target: Model diagram shown in Figure 8 - Structure: Superstructure (superstructure 17) 13 stages, suspension structure (suspension structure 19) 1 stage - Inclined sliding bearing (sliding bearing 30): μ = 0.012, inclination angle θ = 1.5°
- An oil damper with 10% damping will be used. - The primary period of the superstructure is Tu = 0.415 sec, and the effective mass is Meu = 54831 kg.
- Suspension structure: Primary period Td = 0.164 sec, effective mass Med = 5170 kg

<Parameters>
(1) Seismic Waves The seismic waves used in the analysis are shown in Table 1. The waveforms of the seismic waves used for analysis are shown in Figure 9.

(2) Ratio of TMD to effective mass - In the case of upper TMD (upper vibration damping device 20A) The ratio of the mass mu of the TMD used to the effective mass Meu of the superstructure (mu/Meu): mu/Meu = 3%, 5%, 7%, 9%.
- In the case of a lower TMD (lower vibration damping device 20B), the ratio of the mass md of the TMD used to the effective mass Med of the suspension structure (md/Med) shall be md/Med = 10%, 20%, 30%, or 40%.

<Analysis results>
Figure 10 shows the acceleration at the upper end of the superstructure, Figure 11 shows the acceleration at the upper end of the suspension structure, and Figure 12 shows the seismic isolation displacement. In all figures, (a) El Centro, (b) Taft, and (c) Hachinohe.
We conducted an analysis of the case where TMDs are installed at the upper and lower ends of a seismically isolated EVA (elevator).
(Regarding acceleration)
- The effect of the upper TMD on the acceleration at the upper end of the EVA is greater than that of the lower TMD.
Looking at the mass ratio (mu/Meu) of the upper TMD, the greatest reduction in acceleration was observed across all cases when it was around 7% to 9% of the effective mass Meu. While the effect was greater at 9% or higher than at 7%, the change was not as significant.
- The effect of the lower TMD on the acceleration at the lower end of the EVA is greater than that of the upper TMD.
Looking at the mass ratio (md/Med) of the TMD, the greatest reduction in acceleration is observed across all cases when the effective mass (Med) is around 10% to 20%. Beyond 20%, performance can actually worsen in some cases. Considering cost, the optimal mass for the lower TMD is around 10% of the effective mass.
It was found that attaching TMDs to the upper end of the superstructure and the lower end of the suspension structure, tailored to their respective periodic characteristics, has a synergistic effect in reducing acceleration.
(Seismic isolation displacement)
The effect of installing both an upper TMD and a lower TMD is small, but noticeable.

In the seismic isolation and damping composite system 2 configured in this way, an upper damping device 20A, which functions as a TMD, is provided at the top of the superstructure 17, and a lower damping device 20B, which functions as a TMD, is provided at the bottom of the suspension structure 19. Since the sliding bearing 30 supporting the lower part of the superstructure 17 does not have a natural period, the synchronization period of the TMD mechanism can be set to the primary period of the structure in the non-seismic isolation state (with the seismic isolation layer fixed), without being affected by the rigidity of the sliding bearing 30, making it easier to determine the TMD specifications (movable mass, spring, and damping specifications). This reduces the influence of the characteristics of the input seismic wave and prevents resonance with the seismic wave. During an earthquake, both the acceleration at locations above the center of gravity of the structure, such as the superstructure 17, and the acceleration at locations below the center of gravity, such as the suspension structure 19, can be reduced.

Furthermore, since the mass of the upper vibration damping device 20A is 7% to 9% of the effective mass of the upper structure 17, the acceleration of the upper structure 17 and the suspension structure 19 can be reliably reduced.

Furthermore, since the mass of the lower vibration damping device 20B is 10% to 20% of the effective mass of the suspension structure 19, the acceleration of the upper structure 17 and the suspension structure 19 can be reliably reduced.

Furthermore, by attaching TMDs to the uppermost part 17u of the superstructure 17 and the lowermost part 19d of the suspension structure 19, in accordance with their respective periodic characteristics, a synergistic effect is achieved in reducing acceleration.

Furthermore, by using the sliding bearing 30 in combination with the upper and lower TMDs (upper vibration damping device 20A and lower vibration damping device 20B), the same effect as rigid body movement can be achieved even in structures with low rigidity, such as elevators.

Furthermore, the assembly procedure, shapes, and combinations of the constituent members shown in the above-described embodiment are merely examples and can be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention.

For example, in the embodiments described above, an elevator was used as an example of the suspension structure 19, but the present invention is not limited to this. A general suspension structure can also be applied as the suspension structure 19.

Furthermore, although the above-described embodiment uses an inclined sliding bearing as an example of the sliding bearing 30, the present invention is not limited to this. An inclined elastic sliding bearing or a spherical sliding bearing, as disclosed in Japanese Patent Application Publication No. 2019-138376, can also be used as the sliding bearing 30.

1. Building 2. Vibration isolation and damping composite system 17. Superstructure 17u. Topmost part 19. Suspension structure 19d. Bottommost part 20. Vibration damping device 20A. Upper vibration damping device 20B. Lower vibration damping device.

Claims (3)

A vibration isolation and damping composite system installed in a building comprising a superstructure and a suspended structure suspended from the superstructure,
An upper vibration damping device, which is provided at the very top of the superstructure and functions as a TMD,
A sliding support that supports the lower part of the aforementioned superstructure,
A vibration isolation and damping composite system comprising a lower vibration damping device provided at the lowest part of the suspension structure and functioning as a TMD. The vibration isolation and damping composite system according to claim 1, wherein the mass of the upper vibration damping device is 7% to 9% of the effective mass of the upper structure. The vibration isolation and damping composite system according to claim 1 or 2, wherein the mass of the lower vibration damping device is 10% to 20% of the effective mass of the suspension structure.