JP3203374B2 - Double floor vibration damping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double floor (commonly referred to as a free access floor) used for constructing an installation room for an information processing apparatus, a semiconductor manufacturing apparatus, and the like. The present invention relates to a double floor vibration damping device that reduces vertical vibration.

[0002]

2. Description of the Related Art A conventional double floor of this type will be described with reference to the drawings. FIG. 4 is a schematic diagram of a building. 1 is a building and 2 is a floor slab. In FIG. 4, a vertical vibration N is generated in a floor slab 2 of a building 1 by an earthquake motion M during an earthquake. Particularly, in the floor slab 2 having a long span structure, FIG.
As shown by the broken line in the middle, this vibration tends to increase. Note that, in the building 1 and the floor slab 2, the vertical vibration N is generated at any time due to peripheral road traffic, a machine having a rotating mechanism, and the like, even during normal times.

Computers, semiconductor manufacturing equipment, and the like are usually installed on a double floor from the viewpoint of ensuring the convenience of air-conditioning equipment and wiring and piping. In order to protect against functional impairment, a double floor called a base-isolated floor (or anti-vibration floor) that reduces vibration on the double floor has been considered.

FIG. 5 shows a general double-bed structure. In the figure, 3 is a building floor slab, 4 is a double floor support, and 5 is a floor panel. In general, as shown in FIG. 5, a double floor is constructed by arranging a plurality of double floor supports 4 on a building floor slab 3 at equal intervals and bridging over the adjacent upper ends of the double floor supports 4. This is a structure in which the floor panels 5 are placed and spread as described above, and are called free access floors.

Next, a structure generally called a base-isolated floor is shown in FIG.
Shown in In the figure, reference numeral 6 denotes an elastic body for reducing vibration. As shown in FIG. 6, the seismic isolation floor is transmitted between the building floor slab 3 and the group of double floor struts 4 on the double floor, and is transmitted from the building floor slab 3 to the group of double floor struts 4 during an earthquake or the like. A group of elastic members for reducing vertical vibrations, for example, a damping means such as a spring or a shock absorber is interposed. In this case, a structural body 7 such as a lattice beam is usually laid on the elastic body 6 group in order to structurally stabilize the upper part of the double floor column 4 group.

[0006]

In the base-isolated floor shown in FIG. 6, a material for reducing the transmission of vibration is inserted between the building floor slab 3 and the floor panel 5 so that the vibration generated in the building floor slab 3 is inserted. Is not transmitted to the floor panel 5, but the general structure is such that the double floor height is increased by the insertion of the elastic members 6 and the structure 7 such as a lattice beam is provided. There is a problem that it becomes complicated and expensive.

On the other hand, there is a means called a dynamic vibration absorbing mechanism. The dynamic vibration absorbing mechanism is a means for reducing vibrations generated in a structure by attaching an additional mass 10 to a structure 8 via an elastic body 9 as shown in FIG. This is a means for reducing the vibration of the structure 8 itself by generating a vibration that cancels the vibration of the structure 8 in the additional mass 10 by setting the vibration frequency to be substantially the same as the generated frequency.

When this method is used for the vertical vibration of the building floor slab 3, a dynamic vibration absorbing mechanism is installed on the building floor slab 3 instead of the structure 8 to reduce the vertical vibration of the building floor slab 3. It is conceivable to add a normal free access floor. However, if the dynamic vibration absorbing mechanism and the free access floor are separately provided in this way, the dynamic vibration absorbing mechanism may hinder the convenience of the double floor for air conditioning, wiring, and piping.

In order to avoid this, it is conceivable to suspend the dynamic vibration absorbing mechanism below the building floor slab 3, but there is a problem that the scaffold is generally poor and the maintainability is poor.
Further, in the vertical vibration N generated on the building floor slab 3 by the peripheral road traffic, the machine having the rotating mechanism, etc., the excited frequency is limited, and the dynamic vibration absorbing mechanism also targets only the frequency range. However, if the target is an earthquake, it is necessary to cover a wide frequency range because of the strong randomness of the seismic wave.

That is, during an earthquake, vibrations having a plurality of outstanding frequency components are generated in the building floor slab 3, and in order to reduce the vibrations with an appropriate effect, it is necessary to install a plurality of dynamic vibration absorbing mechanisms. There is. For this reason, when trying to reduce vibrations caused by an earthquake, the problem of separately installing the dynamic vibration absorbing mechanism and the free access floor becomes even greater.

Here, the present invention is characterized in that the vertical vibration during an earthquake or the like generated on a double floor is reduced simply and inexpensively without impairing the convenience of the double floor as much as possible. A vibration device is not provided.

[0012]

The above object can be attained by adopting the following novel characteristic constitution means of the present invention. That is, the first feature of the present invention is:
In a double floor structure having a structure in which a plurality of double floor supports are erected on a building floor slab, and floor panels are placed and spread over the adjacent upper ends of the double floor support group, A vertical dynamic vibration absorption mechanism that can adjust the natural frequency to be absorbed by the additional mass attached to the elastic body with the upper end fixed to the lower end of the elastic body with the upper end fixed to the plurality of double-floor struts is distributed to the plurality of double-floor struts. A double floor vibration damper configured so that the dominant frequency of the building floor slab during an earthquake or the like and the combined natural frequency of the vertical dynamic vibration absorbing mechanism are synchronized. Device.

A second feature of the present invention is a double floor vibration damping device in which the vertical dynamic vibration absorbing mechanism according to the first feature incorporates a damping mechanism between an additional mass and a double floor support. .

[0014] A third feature of the present invention is the first or second aspect.
The elastic body of the vertical dynamic vibration absorbing mechanism,
This is a double floor vibration damping device using an elastic body having a damping function.

[0015]

According to the present invention, as described above, the vertical vibration generated on the double floor is reduced for each building slab.
In this case, in the vertical vibration generated on the floor slab by peripheral road traffic or a machine having a rotating mechanism, the frequency excited by the floor slab is limited. For this reason, the dynamic vibration absorbing mechanism only needs to target the excited frequency.

The dashed line in FIG. 3A is a graph showing the Fourier spectrum of the floor vibration waveform in such a case. As is well known, the absorption natural frequency of the dynamic vibration absorbing mechanism is tuned to its spectrum peak. Fig. 3
The vibration can be reduced as shown by the solid line in FIG. However, due to strong random waves (= seismic waves) during an earthquake, double floors and floor slabs generate vibrations with multiple outstanding frequencies, and the Fourier spectrum of the floor vibration waveform is shown in FIG.
As shown by the dashed line in (b), the peak has a complicated appearance with a plurality of or unclear peaks.

For this reason, the dynamic vibration absorbing mechanism needs to cover a wide frequency range, while the dynamic vibration absorbing mechanism can reduce only a specific frequency component as described above. A dynamic vibration absorbing mechanism capable of adjusting the natural frequency of absorption was dispersed and installed on a plurality of double-floor struts.

That is, by appropriately dispersing and setting the natural frequency of each of the dispersed dynamic vibration absorbing mechanisms to a plurality of peak portions of an assumed floor vibration spectrum at the time of an earthquake, Since the predominant frequency of the floor slab during the earthquake and the natural frequency synthesized by the dynamic vibration absorption mechanism are synchronized, the vertical vibration generated on the double floor during the earthquake as shown by the solid line in FIG. It is possible to reduce well.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG.
Is a perspective view of a double floor to which the double floor vibration damping device of the present embodiment is attached, and FIG. 2 is a front view of one double floor support to which a dynamic absorption vibration structure is attached. In the figure, A is the double floor vibration damping device of the present embodiment,
11 is a dynamic vibration absorbing mechanism, 11a is an elastic body, 11b is an additional mass, 12 is a tension coil spring, 13 is a weight that can adjust the number of superposed sheets 13a, 14 and 15 are cylindrical vertical spring holders, and 16 is a support. Prop head, 17 is a welding bolt, 1
Reference numeral 8 denotes a cap nut, reference numeral 19 denotes a support base plate whose height can be adjusted, reference numeral 20 denotes a weight suspension bolt, and reference numeral 21 denotes a lattice floor beam. The same members as those in the conventional example are denoted by the same reference numerals.

The specification of the double floor vibration damping device A of the present embodiment shows such a specific embodiment, and a more detailed embodiment will be described below. The double floor vibration damping device A is a dynamic vibration absorbing mechanism including an elastic body 11a and an additional mass 11b for a double floor including a building floor slab 3, a double floor support 4, a floor panel 5, and a lattice floor beam 21. 11 to the desired plurality of double floor supports 4
It is configured by attaching to each of.

The dynamic vibration absorbing mechanism 11 has an elastic body 11a of a tension coil spring 12 which is fixedly wound around an upper end thereof on an upper spring holder 14 which is inserted through and fixed to the upper part of the double floor support 4, and is wound and mounted on the double floor support 4. And the lower end of the extension coil spring 12 is wrapped around and fixed to the lower spring holder 15, and the lower part of the double floor support 4 is slidably inserted through the lower end of the lower spring holder 15 so that an appropriate number of plates 13
It is composed of two members having an additional mass 11b suspended by a weight suspension bolt 20 penetrating a weight 13 in which a is superposed.

Here, in order to make the natural frequency of the dynamic vibration absorbing mechanism 11 adjustable, the effective vibration length of the tension coil spring 12 is wound around the upper and lower spring holders 14 and 15 so that the rigidity of the tension coil spring 12 can be changed. It can be changed by changing the mounting position. Further, the weight 13 is configured to be divided into a plurality of plates 13a so that the additional mass 11b can be adjusted. Further, the lower spring holder 15 and the double floor support 4
In between, a damping characteristic of the dynamic vibration absorbing mechanism 11 can be adjusted by incorporating a friction damping mechanism, thereby increasing the vibration damping ability.

The tension coil spring 12 may be any elastic body having a spring characteristic in the vertical direction, but it is essential that the natural frequency can be adjusted. Further, a damping property may be added by using a viscoelastic body having a damping function as the elastic body, and the vibration damping ability may be enhanced.

Such a dynamic vibration absorbing mechanism 11 is installed dispersedly on a plurality of double-floor struts 4, and is distributed in the predominant frequency region of the building floor slab 3 assumed during an earthquake.
Double floor vibration control device A by appropriately adjusting each natural frequency so that the synthesized natural frequencies of
Is configured. By doing so, the result is that the dynamic vibration absorbing mechanism 11 is configured with respect to the vertical vibration generated in the building floor slab 3 at the time of the earthquake, so that the effect of reducing the vertical vibration of the building floor slab 3 is generated. Vibrations of the constructed double floor are also reduced at the same time.

[0025]

As described above, according to the present invention, since the double-floor support itself constitutes a dynamic vibration absorbing mechanism, the vertical vibration generated on the double-floor during an earthquake or the like can be reduced by the convenience of the double-floor. The advantage is that the vibration of the building floor slab can be reduced simply and inexpensively without damaging the vibration. For this reason, it is useful for protecting computers and semiconductor manufacturing equipment on double floors from functional failure due to vibrations such as earthquakes, especially for floor slabs with a long span structure where the vertical vibration tends to be large. Exerts excellent utility and usefulness, such as being extremely effective.

[Brief description of the drawings]

FIG. 1 is a perspective view of a double floor provided with a double floor vibration damping device according to an embodiment of the present invention.

FIG. 2 is a front view of one double-floor support having the dynamic vibration absorbing mechanism attached thereto.

FIG. 3 is a graph showing a state of a Fourier spectrum of a floor vibration waveform, wherein a broken line in (a) shows a state of a wave caused by peripheral road traffic and a machine having a rotating mechanism, a solid line shows a state of a reduced wave, and (b) The broken line in () is a graph showing the state of a wave at the time of an earthquake, and the solid line is a graph showing the state of a reduced wave.

FIG. 4 is a schematic sectional view of a building.

FIG. 5 is a longitudinal sectional view of a double floor according to the prior art.

FIG. 6 is a longitudinal sectional view of the seismic isolation floor according to the first embodiment.

FIG. 7 is a schematic diagram illustrating the principle of a dynamic vibration absorbing mechanism.

[Explanation of symbols]

 A: Double floor vibration damping device 1: Building 2: Floor slab 3: Building floor slab 4: Double floor support 5: Floor panel 6, 9, 11a Elastic body 7: Structure 8, Structure 10, 11b ... Additional mass 11: Dynamic vibration absorbing mechanism 12: Tension coil spring 13: Weight 13a: Plate 14, 15: Vertical spring holder 16: Supporting column head 17: Implanted bolt 18: Bag fixing nut 19: Support base base 20 ... Weight suspension bolt 21 ... Lattice floor beam

Continuing on the front page (72) Inventor Hitoshi Okita 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Takaharu Seki 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Stock Inside the company (72) Inventor Yukio Sawabe 5-8 Akihabara, Taito-ku, Tokyo Inside NTT Building Research Institute (72) Inventor Takehiko Okushima 1-1-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Naka Technology Research Institute (72) Inventor Takao Okumura 1-1-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo Inside Naka Technology Research Institute Co., Ltd. (72) Tatsuo Shoji 1-1-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo Naka Technology Co., Ltd. Inside the research laboratory (72) Inventor Seiji Shimura 1-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo Inside the Naka Technical Research Institute Co., Ltd. (56) References JP 4-19344 (JP, B2) (58) Fields investigated (Int .Cl. ⁷ , DB name) E04F 15/024 605 E04F 15/18 601

Claims (3)

(57) [Claims] 1. A double-floor structure in which a plurality of double-floor struts are erected on a building floor slab, and floor panels are placed and laid so as to bridge between adjacent upper ends of the double-floor strut groups. A vertical dynamic vibration absorbing mechanism capable of adjusting a natural frequency to be absorbed by a mounting condition of an additional mass which is integrally mounted on a lower end portion of an elastic body having an upper end portion fixed to the double floor support so as to be vertically vibrated; Dispersed in columns and slidable up and down freely and suspended, the dominant frequency of the building floor slab during an earthquake and the like and the vertical dynamic vibration absorption mechanism attached to the plurality of double floor columns were synthesized. A double floor vibration damping device configured to tune the absorption natural frequency. 2. The double floor vibration damping device according to claim 1, wherein said vertical dynamic vibration absorbing mechanism incorporates a damping mechanism between an additional mass and a double floor support. 3. The elastic body of the vertical dynamic vibration absorbing mechanism uses an elastic body having a damping function.
Or the double floor vibration damping device according to 2.