JP2002188321A - Vibration control structure for tower body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration control structure for protecting a tower body such as an antenna or a lighting rod installed high on the roof of a building from fatigue and damage caused by vibration due to a large earthquake and strong wind. SOLUTION: A lower end part of the tower body is supported by a structure which is regarded as a pin or a pin roller for a roof structure of the building. A supporting member which is installed on the roof of the building and is regarded as a rigid body and a lower part of the tower body are coupled by vibration control elements by a spring and a damper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called tower or rod-shaped tower which is installed high on the roof of a building, such as an antenna of a television, a radio, a mobile phone, or a lightning rod, which is subjected to vibrations caused by a large earthquake or a strong wind. Belongs to the technical field of vibration damping structures that protect against fatigue and damage caused.

[0002]

2. Description of the Related Art A tower having a height greater than its width is very susceptible to shaking due to an earthquake or wind, and there is a great concern about fatigue and damage. In particular, it is known that when a tower 4 that rises high on the roof of the building 1 as shown in FIG. Towers such as antennas and lightning rods installed on the roof of the building not only lose their original functions due to fatigue and damage due to shaking during an earthquake, but also have a large risk of secondary disasters due to destruction and fall, There is a strong demand for the development of a technique for suppressing (or damping) the vibration of the tire to prevent fatigue and damage.

[0003] Conventionally, as a vibration control technology of a tower body, for example,

(I) A vibration damping device corresponding to the natural frequency of a tower has been proposed. A technique applied to an antenna together with a collision-type mass damper that is easy to handle is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-126126 as the invention of "antenna pole with vibration damping device".

(II) On the other hand, as a damping technique that does not require tuning, a damping structure using a connection damper is known. An invention "damping structure stack" belonging to this technology is disclosed in Japanese Patent Application Laid-Open No. 6-66048. The vibration model is recognized as shown in FIG.

(III) In addition, JP-A-11-34375
Japanese Patent Application Laid-Open No. H05-66048 discloses an invention "vibration damping structure" of a technique similar to the invention described in Japanese Patent Application Laid-Open No. 6-66048. The vibration model is as illustrated in FIG. 6A (refer to FIG. 11 described in the publication).

(IV) The invention “support structure for a tower or a column and a damper used for the same” described in Japanese Patent No. 3050758 has a vibration model as shown in FIGS. 7 (1) and 7 (2). , The tower or the column is divided into upper and lower parts at the middle part, and a damper is installed at the divided part so as to exert a damping effect on the rotational deformation of the upper part supported in the pin state.

[0008]

[Problem to be Solved by the Invention] (1) The vibration damping technique of the above (I) is pointed out as a disadvantage of the mass damper that the suitability of the cycle tuning greatly affects the vibration damping performance. Can be Particularly, in the case of a tower placed high on the roof of a building, it is difficult to set the tower because the natural period is different from the natural period of the tower itself due to the vibration of the building. Furthermore, since the weight of the building is larger than the weight of the antenna, fine fluctuations in the vibration characteristics of the building greatly affect the higher-order modes on the natural period of the tower, but the tuning is changed according to this fluctuation. It is practically impossible to do so. In general, the weight of the mass damper is several times as large as
Since it is necessary to oscillate by several times, it is very difficult to design an appropriate mass damper for a level at which damage to the tower body is a problem.

(Part 2) On the other hand, the technique disclosed in Japanese Patent Application Laid-Open No. Hei 6-66048 of the above-mentioned (II), which is a technique similar to the above-mentioned vibration-suppressing technique (I), is recognized as a vibration-damping structure which does not require tuning. FIG. 5A shows a vibration model of the damping structure stack, and the effect of the damper a is proportional to the amount of deformation of the damper as shown in FIG. 5B.
It can be seen that the lowermost damper a ′ in FIG. 5A can hardly exert a vibration damping effect. In addition, the displacement amount δ of the tower body top point A
Aside from that, it is clear that the overall bending deformation of the tower itself is quite large. In addition, since it is assumed that the upper part of the tower is connected to the damper a, it cannot be implemented when the appearance of the top of the tower is problematic. Further, the configuration in which only the lower layer portion is connected to the damper a has a disadvantage that the vibration damping effect is small and the vibration damping structure becomes impractical.

(Part 3) JP-A-11-3 of the above (III)
As shown in FIGS. 6A and 6B, a vibration damping structure disclosed in Japanese Patent Application Laid-Open No. 6-66048 discloses a vibration model and a state of vibration. It is a technique similar to a stack and has similar problems.

(Part 4) Patent No. 3050 of the above (IV)
No. 758 describes a "support structure for a tower or a column and a damper used for the same", and its vibration model is shown in FIG.
As exemplified in (1) and (2), the tower or the pillar is divided into upper and lower parts at the middle part, and a damper a is installed at the divided part so as to exert a damping effect on the rotational deformation of the upper part. ing. Therefore, the force generated in the damper a and the spring c is very large. In addition, since the damper a and the spring c directly bear the upper load, there is a disadvantage that the damper becomes very large.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vibration damping structure for a tower which has a simple structure, requires a small load, does not require setting or adjustment, and has an excellent vibration damping effect. .

[0013]

As a means for solving the above-mentioned problems of the prior art, a damping structure for a tower according to the present invention is a tower-like or rod-like tower installed on the roof of a building. In the vibration damping structure, the lower end of the tower body is supported by a structure that can be regarded as a pin or a pin roller with respect to the roof structure of the building, a supporting member that can be regarded as a rigid body installed on the roof of the building, and the tower body Are connected to each other by a damping element such as a spring and a damper.

According to a second aspect of the present invention, in the vibration damping structure for a tower body according to the first aspect, the damping element such as a spring and a damper is constituted by using a viscoelastic body or a high damping rubber. Features.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a tower body vibration damping structure according to the present invention.

In the embodiment shown in FIGS. 1 and 2, a steel tower 3 supported by a gantry 2 is built on the roof of a building 1, and an example of a tower-like or rod-like tower body is provided at the tip (upper end) of the steel tower 3. This is a vibration damping structure when the lightning rod 4 is installed.

The lower end of the column 4a supporting the lightning rod 4 at the tip is provided on the upper part of the steel tower 3 which is a rigid supporting member provided on the roof of the building 1, specifically, as shown in FIG.
It is installed as shown in (2).

That is, the lower end of the strut 4a of the lightning rod 4 is inserted slightly (several meters) into the upper end of the steel tower 3 having a steel frame assembly structure, and the lower end is supported by the table 5. . The support portion 6 is supported by a structure that can be regarded as a so-called pin or pin roller.
For example, using a lubricating PTFE (tetrafluoroethylene) or the like, a structure is used in which the force in the horizontal direction is transmitted, but slides freely in the vertical direction. That is, the structure does not support the vertical load of the lightning rod 4 and the support 4a. However, as long as the condition for supporting the support portion 6 with a structure that can be regarded as a pin is satisfied, the support portion 6 may or may not support the vertical load of the tower. A part or all of the vertical load of the tower body may be borne by the support portion 6.

On the other hand, a horizontal mounting member 7 is fixed at a fulcrum position slightly above the column 4a, and the mounting member 7 is fixed by a high damping rubber bearing 8 installed on a base 9 at the upper end of the steel tower 3. Supported.

The vibration model of the vibration damping structure according to the present invention, as shown in FIG.
Is a so-called pin structure, and the supporting member 3 which can be regarded as a rigid body installed on the roof of the building, and the lower part of the column 4a (tower body) are made of a vibration damping element (that is, a high damping rubber bearing) by a spring c and a damper a. 8) (the invention according to claim 1).

Therefore, as shown in FIG. 2 (2) and FIG. 3 (2), the high damping rubber bearing 8 is sheared and deformed by horizontal force such as wind or earthquake to absorb energy. The support 4a and the lightning rod 4 are tilted about the support portion 6 having the pin structure as a fulcrum while maintaining a straight line state. Therefore, although the displacement of the top A of the lightning rod 4 becomes considerably large, the tower itself hardly undergoes bending deformation.

As is apparent from the above vibration state, the damping element 8 formed by the spring c and the damper a is not limited to the high damping rubber bearing 8. Even when a combination of the spring c and the damper a is used as shown in FIG. 3A, the present invention can be implemented in exactly the same manner (the invention according to claim 2).

As the spring c, a coil spring, a leaf spring or the like can be used, and as the damper a, an oil damper, a viscous damper, a lead damper, a viscoelastic damper or the like can be applied. Further, as the pin, the support portion 6 of the pin structure can be a mechanical pin or a plate material having a smaller bending rigidity than the axial rigidity.

FIG. 3 shows a vibration model of the vibration damping structure.
As is clear from (1) and FIG. 3 (2) showing the state of vibration, since the supporting portion 6 at the lower end of the column 4a is a pin supporting structure, the displacement of the tower body top point A during vibration is Even if it is large, the bending deformation of the tower itself is small (maintains a substantially linear state). Since the force generated in the damper a and the spring c is extremely small, and it is not necessary for the damper a and the spring c to bear and support the tower body weight, it can be implemented with a simple and small structure.

FIG. 4 shows the maximum response acceleration (results of the analytical investigation of the damping effect) of each part in the embodiment of FIG. 1 in the case where the lightning rod 4 is rigidly joined and the damping is not damped (the hatched graph). And the case where vibration is suppressed by the structure of the present invention (open bar graph). x indicates the X-axis direction, and y indicates the Y-axis direction.

When the white bar graph of the graph 10 showing the damping effect of the tower body portion is compared with the hatched graph, the maximum response acceleration is reduced to about 60 to 70%. I understand the process well. In addition, in the case of the present invention, since the vibration is quickly converged (settled down), an excellent effect against fatigue due to repetition is exhibited.

[0027]

The vibration damping structure for a tower according to the first and second aspects of the present invention has a simple structure, requires only a small load such as the weight of the tower, and has troublesome setting (adjustment). In addition, because of its excellent vibration damping effect, there is no fear of fatigue and damage, and there is no worry about functional damage and secondary disasters caused by destruction and fall.

[Brief description of the drawings]

FIG. 1 is an elevation view of a main part showing an embodiment of a tower body vibration damping structure according to the present invention.

FIG. 2A is a detailed view of a vibration damping structure, and FIG. 2B is a view showing a state of vibration.

3A is a vibration model diagram of the present invention, and FIG. 3B is an analysis diagram showing a state of vibration.

FIG. 4 is a comparison diagram of response acceleration in the embodiment of the vibration damping structure of FIG. 1;

FIG. 5A is a diagram illustrating a vibration model according to the related art, and FIG. 5B is a diagram illustrating a state of vibration.

FIG. 6A is a diagram illustrating a vibration model according to the related art, and FIG. 6B is a diagram illustrating a state of vibration.

FIG. 7A is a diagram illustrating a vibration model according to the related art, and FIG. 7B is a diagram illustrating a state of vibration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Building 3 Steel tower (support member) 4 Lightning rod (tower body) 6 Support part (pin structure) 8 High damping rubber bearing a Damper c Spring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Sugibayashi 8-21-1, Ginza, Chuo-ku, Tokyo Inside Tokyo Head Office Takenaka Corporation (72) Inventor Satoru Aizawa 1-5-5 Otsuka, Inzai City, Chiba Prefecture 1 Inside Takenaka Corporation Technical Research Institute (72) Inventor Gen Taniguchi 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside 1 Takenaka Corporation Technical Research Center (72) Inventor Kiyoto Masumura Ginzaha, Chuo-ku, Tokyo 21-21 Chome Takenaka Corporation Tokyo Main Store 8-21-1, Ginza, Chuo-ku F-term (reference) 3J048 AA01 AD16 BA04 BD08 DA04 EA29 EA38 5J047 AA10 AB00 AB06 BC01 BC06 DA00

Claims (2)

[Claims] 1. A damping structure for a tower or bar-like tower installed on the roof of a building, wherein the lower end of the tower is supported by a structure that can be regarded as a pin or a pin roller with respect to the roof of the building. That the supporting member, which can be regarded as a rigid body, installed on the roof of the building, and the lower part of the tower are coupled by a damping element such as a spring and a damper, respectively. Construction. 2. The damping structure for a tower according to claim 1, wherein the damping element such as a spring and a damper is made of a viscoelastic body or a high damping rubber.