JP2586903B2 - Free access floor with vibration control function - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free access floor used for a floor structure of a computer room or the like, and relates to a free access floor having a vibration control function.

"Conventional technology" In recent years, building and civil engineering structures have become higher-rise, diversified, and lighter in weight due to factors such as the development of high-strength materials, advances in machining technology, and the development of structural analysis technology using computers. It has a structure that is highly flexible against external forces. And, in such a lightweight and flexible structure, its natural frequency is low and the internal vibration damping tends to be small, so that various vibrations which cannot be expected due to the influence of an external force such as an earthquake or a wind are generated. Can occur.

Further, with the recent shift to office automation, rooms for installing precision electronic devices such as computer rooms are rapidly increasing in buildings. In the computer room and the like, a floor structure of a free access floor is often used to protect the electronic devices and the like from vibration transmitted from a structure or vibration transmitted directly when walking in the room. It is being adopted.

Here, the free access floor will be briefly described with reference to FIG. 9. In FIG. 9, reference numeral 1 denotes a slab of a structure, and support legs 2, 2,. And between the support legs 2, 2, ..., beams 3, 3, ...
Are installed, and floor plates 4, 4,... Of a predetermined shape made of an aluminum precast plate or the like are arranged on the upper portion thereof without any gap. In this free access floor, the support legs 2 are provided. Due to the flexibility described above, the vibration transmitted from the slab or the like is made longer to reduce the acceleration of the vibration.

"Problems to be Solved by the Invention" However, in the conventional free access floor, since the vibration is lengthened by the flexibility of the support legs, the displacement of the floorboard increases,
There has been a problem that the floor slab continues to shake for a long time due to a decrease in the damping rate of the vibration, which adversely affects the electronic device and the like.

The present invention has been made in view of such circumstances, and it is possible to suppress vibration in a short time when the floor surface vibrates without impairing the seismic isolation function of the conventional free access floor. The purpose is to provide a free access floor having a vibration control function.

"Means for Solving the Problems" The present invention provides a floor panel disposed above a slab of a structure via a supporting leg having a seismic isolation function, and a device such as a computer mounted on the floor panel. On a free access floor designed to protect against vibration, a storage chamber capable of storing liquid is provided on the lower surface of the floor plate, and the same natural vibration period as that of the floor plate in a state in which the device is mounted on the upper portion in the storage room. A liquid that oscillates at a vibration period of and with a required phase difference from the natural vibration.

[Operation] In the present invention, the vibration transmitted from the slab is reduced by increasing the period of vibration by the seismic isolation function of the conventional free access floor to reduce the acceleration, and the device is disposed above the floor plate. When the liquid starts to oscillate due to the natural vibration of the state, the liquid in the storage chamber installed on the lower surface of the floor plate vibrates at the same vibration cycle as the natural vibration cycle and has a predetermined phase difference from the natural vibration (causing sloshing). It exerts a vibration damping effect and immediately attenuates floor vibration.

Hereinafter, the present invention will be described with reference to the drawings.
1 to 4 show an embodiment of the present invention. FIG. 1 shows a vibration damping device of the present invention used in a floor structure of a computer room on which devices such as electronic devices are mounted. FIG. 2 is a perspective view of a part of a free access floor having a function (one floor plate), FIG. 2 is a plan view thereof, and FIGS. 3 and 4 are side views thereof. In these figures, the same elements as those of the prior art shown in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, a free access floor having a vibration control function (hereinafter simply referred to as an “access floor”) is fixed to an upper part of a slab 1 of a structure. It has been placed. A storage tank 10 formed in a rectangular parallelepiped by a plate material such as plastic is installed on the lower surface of the floor plate 4. In this embodiment, the inside of the storage tank 10 is vertically
By dividing into four layers and four planes, a total of eight storage chambers R, R,... Having the same shape are formed. At predetermined positions of the floor plate 4 which also serves as a ceiling plate of the storage tank 10, openings 12, 12 are formed separately and communicate with the upper two storage chambers R, R, respectively. One is storage tank 10
The other is used as an inlet for the liquid W into the storage tank 10, and the other as an outlet for air in the storage tank 10. further,
As shown in FIG. 3 (a), a partition plate 11 for vertically dividing the floor plate 4 and the storage tank 10 is provided in the upper storage chamber R other than the above.
And a communication hole 13a communicating with the storage chamber R is formed in the upper part of the pipe member 13, as shown in FIG. A communication hole 14 communicating with the pipe member 13 is formed in the partition plate 11 to which the member 13 is fixed, thereby forming a communication pipe for the upper and lower storage chambers R. Further, the storage tank 1
A communication hole 1 for communicating the storage chambers R, R,.
Are formed.

The storage chamber R has an amount of liquid that oscillates at the same vibration cycle as the natural vibration cycle of the floor plate 4 in a state where a device such as a computer is mounted on the upper part, and with this natural vibration and a required phase difference. W is formed in such a shape as to be stored therein, and the inside thereof has a necessary amount of liquid W (in this embodiment, each of the storage chambers R, R,... Has been stored). In addition, the storage tank
10 is such that the total mass of the liquid W in each of the storage chambers R, R,... Is 1/50 to 1/200 of the mass of a device (not shown) mounted on the upper part of the access floor. It is desirable that the shape is set so as to fall within the range. Therefore, the number of the storage tanks 10 is appropriately increased or decreased according to the number, weight, or arrangement state of the devices installed on the floor plate 4, and the number of the floor plates 4, 4,.
... and properly placed at the bottom of each storage tank 10,10, ...
-The total mass of the liquids stored therein may satisfy the above condition.

The size of the communication holes 15, 15,...
Of course, the magnitude of the vibration of the liquid W generated in R, R,... Is set so as not to affect each other. Are formed on the inner surfaces of the storage chambers R, R,..., Thereby increasing the frictional force between the liquid W and the inner surfaces of the storage chambers R, R,. Can be adjusted. Further, the storage tank 10 is preferably formed of a material that does not corrode even during long-term use. Similarly, the liquid W is preferably a liquid that does not easily evaporate even during long-term use. However, the materials of the storage tank 10 and the liquid W may be appropriately determined according to the construction conditions and the like, and are not limited to the above-described materials. When the storage tank is made of a steel plate, the durability of the storage tank itself can be increased by mixing a rust inhibitor into the liquid W.

Next, the operation of the access floor according to the present invention configured as described above will be described along with its use example.

The natural vibration period when the floor plate 4 vibrates corresponds to the number, weight, and arrangement state of the devices mounted thereon. The natural oscillation period of the liquid W stored in the storage tank 10 is determined by the shape of the storage tank 10, the depth of the liquid W, the viscosity, and the like. Therefore, the natural oscillation cycle of the liquid W in the storage tank 10 is the same as the natural oscillation cycle of the floor plate 4, and the liquid W oscillates with a predetermined phase difference from the floor plate 4 in the storage tank 10. A fixed amount of liquid W is injected. That is, in accordance with the number, weight, and arrangement of the devices installed on the floor plate 4, the appropriate number of storage tanks 10, 10,... Disposed at the bottom of each floor plate 4, 4,.・ Reservoir R,
A predetermined amount of liquid W is injected into R,... At a uniform level. First, a predetermined amount of liquid W is injected into the storage tank 10 from the injection port 12, and then the storage tank 10 is
Is set up so that the storage room R on the side where is fixed is located on the lower side. By doing so, the liquid W accumulates in the lower four storage chambers R through the pipe member 13 and the communication holes 15 and 15 and gradually becomes a uniform level therein. After the liquid W accumulated in the four storage chambers R has reached a uniform level in each of the storage chambers R, the storage tank 10 is returned to the original state again, and this time, the liquid W passes through the communication holes 15, 15. Liquid W flows into storage chambers R, R,... Adjacent in the direction, and an appropriate amount of liquid W is stored in each of the eight storage chambers R, R,. Will be done. Liquid W into storage tank 10
After the liquid is stored, the inlets 12, 12 are closed by a predetermined method to prevent the liquid inside from being spilled or evaporated and reduced.

Thus, the access floor of the present invention reduces the acceleration by extending the vibration transmitted from the slab 1 or the like by the seismic isolation function of the support leg 2 and reduces the acceleration. When it starts to shake due to natural vibration,
The liquid W in the storage chamber R of the storage tank 10 installed on the lower surface of the floor plate 4 is controlled by vibrating (sloshing) at the same vibration period as the natural vibration period and with a predetermined phase difference from the natural vibration. A vibration effect can be exerted, the vibration of the floor plate 4 can be immediately attenuated, and the upper device can be protected from the vibration.

In the storage tank 10, the level of the liquid W in the storage chamber R is determined at a glance in order to periodically check whether a predetermined amount of the liquid W stored in the storage chamber R is stored. It is good to have a scale so that you can check it. For example, what is shown in FIG. 4 is to examine a point p at which the water surface generated in the storage chamber R by raising one end and inclining at a predetermined angle intersects with the indication line 1 previously written in the storage chamber R. Thus, the amount of liquid is checked. By doing so, the error in the liquid level is enlarged, and a slight decrease in the liquid can be checked.

Here, the damping action of the storage tank installed on the access floor will be described.

Access floor with equipment mounted on top (hereinafter referred to as
Storage tank 10 having a “vibration Mass”) and a storage chamber R
Can be approximated and simplified to a vibration model as shown in FIG. The vibration model, through the spring 20A and dashpot 21A attenuation factor h ₀ of the spring constant K _0, the mass M vibration system object 22A is supported for ₀ A (vibration model of the vibration Mass), the spring constant via a spring 20B and dashpot 21B attenuation factor h ₁ of K _1, the object 22B of mass M ₁
System B (vibration model of storage tank) supported by
Are connected in series.

Here, the storage tank includes a plurality of storage chambers R, R, ..., and the liquids W, W, ... stored in the storage chambers R, R, ...
.., But the vibration cycle of the liquid W stored in each storage chamber R matches the natural vibration cycle of the vibration Mass, so that these liquids W, W,. Vibrates together. Therefore, as described above, there is no problem even if the storage tank is approximated by one vibration system B.

In such a vibration model, when the vibration system A starts to vibrate due to an external force such as an earthquake or a wind applied to the object 22A, the vibration system B starts to vibrate with a predetermined phase delay. By making the vibration periods coincide, the vibration of the vibration system A can be suppressed.

Thus, as the oscillation period T ₁ of the liquid W stored in the respective storage chamber R coincides with the natural vibration period T ₀ of the vibration Mass, by setting the dimensions of the reservoir R, the storage amount of the capacitor and the liquid W Good. The behavior of the liquid W stored in the storage chamber can be analyzed as follows.

The relationship between the j-th natural oscillation period Tj of sloshing and the l-th natural circular frequency ωj is expressed by the following equation.

Tj = 2π / ωj (1) Then, in the above equation (1), if H is the storage depth of the liquid and g is the gravitational acceleration, ωj is an amount given by the following equation.

Further, kj in the above equation (2) is the width of the storage chamber 2a.
Then, it is given by the following equation.

kj = (2j−1) π / 2a (3) Accordingly, the natural oscillation period Tj of sloshing can be obtained from the above equations (1) to (3). May use the natural oscillation period in the first-order sloshing.

Also, the position of the storage tank 10 is not particularly limited, and the liquids W, W,... Stored in the storage tanks 10, 10,.
..As many as the total mass of the vibration Mass is within the range of 1/50 to 1/200 of the mass of the vibration Mass, it is sufficient to arrange them on the lower surface of the access floor. Become.

The results of a simulation experiment performed by the inventor of the present application are shown below to demonstrate the vibration damping effect of the present invention. As an experimental system, as shown in Fig. 6, vibration Mass
Simulated structure S of a five-layer model (mass M ₀ = 400 kg ×
A storage tank 10 of the present invention (total mass M _{1 of} liquid W = 52 kg, primary natural period T ₁ ) is placed on a rooftop having five layers and a primary natural period T ₀ = 0.41 second.
= 0.41 seconds). FIG. 7 shows the displacement of the fourth layer of the simulated structure S without the storage tank 10 when a random wave (BL-CENTRO-NS wave) was applied to such an experimental system. Retained storage tank 10
FIG. 8 shows the displacement of the fourth layer of the simulated structure S in the case where there is. As can be seen from the illustrated results, it can be seen that the vibration of the simulated structure S is suppressed by the damping action of the storage tank.

Furthermore, results of the simulation, the ratio of the total effective mass M ₁ and the mass M ₀ of the structure S of the liquid, by setting the _{M 1 / M 0 = 1 /} 50~1 / 200 ...... (4), effective It was found that a great vibration suppression effect was exhibited. In other words, the mass of the total effective mass M ₁ is structure
If it is 1/200 or less of M ₀ , a sufficient vibration damping effect cannot be obtained, and if it is 1/50 or more, the influence of the mass of the liquid on the structural design of the structure becomes large, which is not so preferable.

Note that other embodiments or technical matters other than the above-described embodiments will be described below.

(I) In the above embodiment, the storage tank 10 is
However, the present invention is not limited to this, and the storage tank may be unitized separately from the floor plate, and may be configured to be detachable by providing an engagement means on the floor plate.

(Ii) In the above-described embodiment, the storage tank is formed in a rectangular parallelepiped. However, the storage tank is not limited to this, and it is a matter of course that the design can be changed to an arbitrary shape. In this case, the above-described theory may be appropriately changed, and the dimensions of the storage chamber R, the storage depth of the liquid, the total stored liquid amount, and the like may be set based on an equation corresponding to the shape. Further, by appropriately disposing a partition plate or the like in the storage chamber to have a wave-eliminating effect, or by changing the liquid to a viscous liquid, it is possible to adjust the vibration damping rate due to the viscous resistance.

[Effects of the Invention] As described in detail above, the present invention provides a floor board disposed above a slab of a structure via a supporting leg having a seismic isolation function, and a computer or the like placed on the floor board In a free access floor designed to protect the device from vibration, a storage chamber capable of storing liquid is provided on the lower surface of the floor plate,
In the storage chamber, a liquid that vibrates with the same vibration cycle as the natural vibration cycle of the floor plate in a state where the apparatus is mounted on the upper part and vibrates with the natural vibration and a required phase difference is stored. Therefore, the vibration is prolonged by the seismic isolation function of the support legs to reduce the acceleration, and when the floorboard starts to sway due to the natural vibration with the equipment etc. installed above it, it is installed on the lower surface of the floorboard When the liquid in the storage chamber vibrates (causes sloshing) with the same vibration cycle as the natural vibration cycle and with a predetermined phase difference from the natural vibration, a vibration damping effect is exhibited, and the vibration of the floorboard is immediately attenuated. Thus, when the floor surface vibrates without damaging the seismic isolation function of the conventional free access floor, there is an excellent effect that the vibration can be suppressed within a short time.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a perspective view of a part of a free access floor having a vibration damping function of the present invention, and FIG. 2 is a plan view of FIG. FIG. 3 (a) is a side view of FIG. 1, FIG. 3 (b) is an enlarged sectional view of a pipe member provided in the storage chamber, and FIG. 4 is a method for checking the liquid amount in the storage chamber. FIG. 5 is an explanatory diagram for explaining
The figure is a schematic diagram showing a vibration model of a vibration Mass and a vibration damping device (storage tank), FIG. 6 is a schematic diagram showing an outline of an experimental system of a simulation experiment, and FIG. 7 is a simulated structure without a storage tank FIG. 8 is a view showing a vibration state of a simulation structure provided with a storage tank, and FIG.
The figure is a perspective view of a conventional free access floor. 1 ... slab, 2 ... support leg, 4 ... floor plate, 10 ... storage tank, R ... storage chamber, W ... liquid.

Claims (1)

(57) [Claims] 1. A free access system in which a floor plate is disposed above a slab of a structure via a supporting leg having a seismic isolation function, and a device such as a computer mounted on the floor plate is protected from vibration. On the floor, a storage chamber capable of storing liquid is provided on the lower surface of the floor plate, and in the storage chamber, the natural vibration period is the same as the natural vibration period of the floor plate in a state where the device is mounted on the upper part, and the natural vibration And a liquid that vibrates with a required phase difference.