JPH03247872A - Vibration isolator for structure - Google Patents

Abstract

PURPOSE:To permit proper and maximum vibration-isolating effects to exhibit all the time by a method in which the first and second spring parts are provided to a supporter, and the spring constant of the second spring part is controlled in such a way that the actual vibration period of a structure coincides with that of an inertial mass part. CONSTITUTION:On a given position of a structure 11, and inertial mass part 13 and a supporter to support the part 13 by permitting its vibration with the same vibrating period as that of the structure 11 are provided. The supporter has the first spring part 17 of a fixed spring constant and the second spring part 15 of a variable spring constant in a manner that both the parts 17 and 15 can vibrate in the same direction. The supporter has also a vibration controller which measures the actual vibration periods of the structure 11 and the part 13 and controls the spring constant of the second spring part 15 to make them coincide.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a vibration suppression device for a structure that suppresses vibrations of a structure that occur when an external force is applied to the structure, and in particular,
The present invention relates to a vibration suppressing device for structures that can exhibit effective vibration suppressing effects over a wide range of vibrations over a long period of time.

"Prior Art" In recent years, attempts have been made to actively suppress the vibrations of structures that occur when external forces such as earthquakes and strong winds act. To achieve this purpose, vibration suppression devices currently proposed can generally be classified into those using an active method and those using a passive method.

The active method detects an external force acting on a structure and actively applies vibration to the structure to cancel out the vibration of the structure due to this external force. Therefore, ■ it requires a huge amount of energy, ■ the equipment is large-scale and requires a vast amount of floor space, ■ it becomes very expensive mechanical equipment, and ■ there are concerns about safety.
There are other problems, and it will take more time to put it into practical use.

On the other hand, in the passive method, when an external force acts on a structure and causes it to vibrate, this vibration is used to passively impart vibrations to the structure that cancel out the vibration. Part of this passive method has already been put into practical use, and its effectiveness in suppressing vibrations in structures has been demonstrated for wind and small to medium earthquakes.

Passive methods: ■ Require almost no external energy; ■ Can be installed even on narrow floor spaces; ■ The cost of the equipment is relatively low; ■ Safety measures are relatively easy. , etc. Compared to the active method,
Currently, it has many advantages. For this reason, the future trend is likely to be toward passive methods, and based on this passive method, optimal control (semi-activation) that can respond to a wide range of external forces will be promoted.

Passive inertial mass method as a typical example of passive method (
T une d M a s s D a m p
e r ) is a system in which the vibration of a pendulum weight attached to a predetermined position (usually at the top) of a structure is caused to resonate with the vibration of the structure, creating a phase difference of 90" between the two, and the inertia of the pendulum is It is based on the principle of suppressing the vibration of structures by the effect.

FIG. 6 is a diagram showing the amplitude characteristics of the structure before and after installing the vibration suppression device based on the passive inertial mass method. Before installing the vibration suppression device, when the structure resonates with an external force (the point where the value of the horizontal axis in FIG. 6 is 1), the amplitude becomes extremely large, as shown by the broken line in the same figure. On the other hand, when a vibration suppression device is installed, the amplitude during resonance is significantly reduced, as shown by the solid line in the figure.

[Problem to be Solved by the Invention] By the way, in the conventional vibration suppressing device based on the passive inertial mass method, in order to maximize the vibration suppressing effect, the natural period of the pendulum must be constantly adjusted to match the structure's natural period. It must be kept consistent with the vibration period. The vibration period of this structure corresponds to the natural period of the structure in the later stages of wind vibration and seismic motion. However, in reality, it is extremely difficult to perfectly match the natural period of a pendulum to the natural period of a structure, especially when the natural period of a structure itself fluctuates due to changes in weight and rigidity over time. Beyond this point, it is even more difficult to match the natural periods of the pendulums.

This invention was made in view of the above circumstances, and by constantly matching the natural period of the vibrating part of the vibration suppressing device to the actual vibration period of the structure, it is possible to withstand a wide range of vibrations over a long period of time. It is an object of the present invention to provide a vibration suppressing device for a structure that can exhibit an effective vibration suppressing effect.

``Means for Solving the Problems'' Therefore, the present invention provides an inertial mass body that is disposed at a predetermined position of a structure and supports the inertial mass body so as to vibrate freely at the same vibration period as that of the structure. In the vibration suppressing device, the support means is provided with a first spring portion having a fixed spring constant and a second spring portion having a variable spring constant, and the first and second spring portions are configured to have a variable spring constant. The second spring parts are arranged so as to be able to vibrate in the same direction, and further, the actual vibration period of the structure and the actual vibration period of the inertial mass body are measured on the support means, respectively. The above problem is attempted to be solved by configuring a vibration suppressing device for a structure that is provided with a control means for controlling the spring constant of the second spring portion so as to match these values.

Here, it is preferable that the support means supports the inertial mass body so as to vibrate freely along two directions, and the control means controls the second It is preferable to increase the spring constant of the spring portion. Furthermore, it is preferable that the second spring portion is an air spring.

"Operation" The operation of the present invention will be explained with reference to FIG. 4 showing the schematic configuration of the present invention.

As shown in FIG. 4, an inertial mass l having a mass M is disposed on the structure 2 so as to be movable in the horizontal direction, and a first spring portion 3 extending in the horizontal direction A body 1 and a structure 2 are connected. The spring constant of this first spring portion 3 is K. is fixed. Moreover, this inertial mass body 1 is further connected to the structure 2 by a second spring part 4 that vibrates in the same direction as the first spring part 3. The spring constant of this second spring portion 4 is set to a variable value. The vibration period T of such a system (pendulum) is given by the following equation.

On the other hand, a sensor (vibration meter) measures the horizontal displacement X of the inertial mass l and the horizontal displacement y of the structure 2,
Measure the period of both. Assume that the results of these displacements x, y and their periods are as shown in FIG. 5, for example. If the period of the inertial mass body 1 is longer than the period of the structure 2, as shown by the solid line in FIG. The period of the inertial mass body 1 is shortened to match.

On the other hand, if the period of the inertial mass body 1 is shorter than the period of the structure 2, as shown by the broken line in FIG. The period of the inertial mass body 1 is extended to match the period. In this way, by appropriately changing the spring constant K of the second spring portion 4, it is possible to constantly obtain an optimum vibration suppressing effect.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 and 2 are diagrams showing a vibration suppressing device for a structure, which is a first embodiment of the present invention. In the figure, what is indicated by the entire reference numeral 10 is a vibration suppressing device for a structure (hereinafter simply referred to as a "vibration suppressing device") which is a first embodiment of the present invention.
), and this vibration suppression device 10 is installed in buildings (
It is provided on the floor F near the roof of structure) 11.

This vibration suppressing device 10 includes a mass body 13 supported from below by a support portion 12, and a pair of reaction walls 14, 14 that are erected on the floor surface F and sandwich this mass body 13.
and a pair of air springs (second spring portions) 15.15 that are respectively inserted between the reaction walls 14.14 and the mass body 13 and extend in a substantially horizontal direction. There is.

The support part 12 is a mounting plate 1 provided on the floor surface F.
6, and a horizontally deformed portion (first
(spring portion) 17. This horizontally deformed portion 17 is formed into a multilayered structure in which laminated rubber or anti-vibration rubber 18, 18, . . . placed at the four corners of the mounting plate 16 sandwich stabilizers 19, 19, . It is composed of layers. This laminated rubber 18 has a structure in which, for example, steel plates and sheet-like rubber are laminated in multiple layers, and mounting plates are provided above and below the laminated rubber, so that displacement in the horizontal direction is allowed, and displacement in the vertical direction is allowed. Displacement with respect to load is restricted. This allows the mass body 13 to vibrate freely in any direction on the horizontal plane. In addition,
The laminated rubber 18 may be replaced by a vibration-proof rubber made only of solid rubber (not laminated with a steel plate).

The mass body 13 is made of, for example, steel plate, lead, concrete, etc., and the weight of the mass body 13 as a whole is usually in the range of 1/150' to 1/600 of the total weight of the building 11. The material, size, etc. are set. That is, if it is too light, vibrations of the building 11 cannot be effectively suppressed, and on the other hand, if it is too heavy, there is a limit in terms of the building structure.

On the other hand, the air spring 15 is a so-called bellows.
It is an air spring of the type, and is composed of a pair of mounting plates 21 and 21 arranged at both left and right ends of a cylindrical rubber bellows 20,
Rings 22, 22, . . . are fitted around the outer periphery of the bellows 20 to restrain expansion in the radial direction. As a result, the air spring 15 can freely expand and contract between its mounting plates 21 and 21, and can freely vibrate in the horizontal direction connecting the reaction walls 14 and 14. That is, these air springs 15.1
The vibration direction of the horizontal displacement portion 17 coincides with one of the vibration directions of the horizontal displacement portion 17.

The inside of the air spring 15 is communicated with an auxiliary tank 24 via a ventilation pipe 23, as shown in FIGS. 1 and 2, and a pressurized cylinder is connected to this auxiliary tank 24 via an introduction pipe 25. 26 are connected. This auxiliary tank 24 has a function of adjusting the internal volume of the air spring 15 in order to adjust the period of the vibration suppressor 10, which will be described later.
has the function of sending pressurized air into the air spring 15 through this auxiliary tank 24. The delivery of this pressurized air is controlled by a solenoid valve 27 provided midway through the introduction pipe 25. Further, an open pipe 28 whose one end is open to the outside air is connected to the electromagnetic valve 27.

At this time, the spring constant of the air spring 15 is approximately expressed by the following formula (
2) is given by

K valve γ Ao' V, ten V.

Here, Vs is the internal volume of the air spring 15, Vt is the internal volume of the auxiliary tank 24, po is the internal pressure of the air spring 15, 80 is the effective pressure receiving area of the air spring 15, and a is the polytropic index, which represents the change in vibration. Sometimes 1. Takes a value of about 4. As can be seen from the opening equation, the spring constant of the air spring 15 is proportional to the internal pressure p0 and inversely proportional to the internal volume V, +V. Therefore, the spring constant of the air spring 15 is its internal pressure p. This can be easily changed by controlling the pressure cylinder 26 into the air spring 15 and the air spring 1.
This can be easily achieved by discharging pressurized air from 5.

From the above, the mass body 13 is supported so as to be able to vibrate in the horizontal direction by the horizontal displacement portion 17 whose spring constant is fixed and the air spring 15 whose spring constant is variable.

Furthermore, as shown in FIG. 2, the vibration suppression device 10 of this embodiment is provided with sensors (vibration meters) 29 and 30 for detecting horizontal displacement of the mass body 13 and the building 11. In addition, calculation means 31.32 are provided for calculating the periods of the mass body 13 and the building 11 from the displacements detected by these sensors 29.30. and,
The opening/closing operation of the electromagnetic valve 27 is controlled based on the difference calculation means 33 which calculates the difference between the periods calculated by the calculation means 31 and 32.

Next, referring to FIGS. 1 and 2, the first embodiment of the present invention will be described.
The operation of the vibration suppressing device 10 according to the embodiment will be explained.

When an external force such as a strong wind or an earthquake acts on a building where the vibration suppression device IO is installed near the rooftop, pressurized air is introduced into the air spring 15, and the vibration suppression device IO introduces pressurized air into the air spring 15 based on equations (1) and (2) above. Thus, the vibration period of the mass body 13 is made to match the first-order natural period of the building 11. Of course, pressurized air may be introduced into the air spring 15 on a daily basis to make the vibration period of the mass body 13 match the first-order natural period of the building 11.

In this state, when the building 11 starts to vibrate horizontally due to the action of the external force, the mass body 13 starts to vibrate with a phase lag of 90" with this building 11. Therefore, the horizontal movement of the building 11 and the mass body 13 Since the directions are delayed by 90 degrees, the vibration of the building 11 is canceled out by the vibration of the mass body 13, and the vibration of the building 11 is suppressed.

At this time, the sensors 29.30 are connected to the mass body 13 and the building 1.
1 and calculates the calculation means 31 based on these displacements.
．． 32 calculates the period. The difference calculation means 33 calculates the difference between the calculated periods of the mass body 13 and the building 11,
If the period of the mass body 13 is short, the electromagnetic valve 27 is activated to exhaust the pressurized air inside the air spring 15 to the outside air through the open pipe 28, thereby reducing the pressure inside the air spring 15.

On the other hand, if the cycle of the mass body 13 is long, the electromagnetic valve 27 operates and the pressurized air in the pressurized cylinder 26 is transferred to the air spring 15.
By introducing the air into the air spring 15, the inside of the air spring 15 is put into a pressurized state. In this way, by appropriately changing the spring constant of the air spring 15, the actual vibration period of the mass body 13 is changed to match the actual vibration period of the building 11. Then, at the stage when the actual vibration period of the mass body 13 matches the actual vibration period of the building 11, the vibration suppressing effect described above is maximized.

Therefore, according to this embodiment, since the actual vibration period of the mass body 13 is changed to match the actual vibration period of the building 11, the vibration suppression device 10 can always achieve optimal and maximum vibration suppression. effect can be obtained. Moreover, this vibration suppression effect remains constant regardless of changes in the weight or rigidity of the building over time.

In addition, on this implementation side, if the horizontal displacement of the mass body 13 becomes excessive, the internal pressure of the air spring 15 on the compression side can be sufficiently increased to function as a safety device (fail-safe device). can. Furthermore, if the air spring 15 is made of a material that can withstand shear deformation, the reaction wall 14
．． It is also possible to provide a degree of freedom for vibration in the horizontal direction orthogonal to the direction connecting the lines 14 to 14.

Next, FIG. 3 is a diagram showing a vibration suppressing device for a structure, which is a second embodiment of the present invention. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

The difference between the vibration suppressing device of the first embodiment and this embodiment lies in the mounting positions of the air springs 15, . . . .

That is, the stabilizer 19 of the horizontal deformation section 17.
19,... have reaction plates 40 on each of their upper and lower surfaces.
, 401... are provided protrudingly, and each stabilizer 1
9. In the space between 19 and 19, reaction plates 4 protrude from the stabilizers 19 and 19 located above and below, respectively.
0140 are arranged facing each other at a predetermined distance. An air spring 15 is disposed between the reaction plates 4o140 disposed at opposing positions.

Therefore, this embodiment also provides the same effects as the first embodiment. In particular, in this embodiment, there is almost no increase in floor space due to the installation of the air springs 15, . . . , and space saving can be achieved. Another advantage is that period adjustment in two directions along the horizontal plane can be performed independently.

Note that the details of the structure vibration suppressing device of the present invention are not limited to the above-mentioned embodiments, and various modifications are possible.

- As an example, in the embodiment described above, the air spring 15 was used as the spring portion with a variable spring constant, but the present invention is not limited to this, and it is of course possible to use other well-known spring means with a variable spring constant. be.

"Effects of the Invention" As explained in detail above, according to the present invention, an inertial mass body is arranged at a predetermined position of a structure, and the inertial mass body has a vibration period that is the same as that of the structure. A vibration suppressing device comprising a support means that supports the vibration freely, the support means is provided with a first spring portion having a fixed spring constant and a second spring portion having a variable spring constant. , the first and second spring portions are arranged so as to be able to vibrate in the same direction, and the support means is provided with an actual vibration period of the structure and an actual vibration period of the inertial mass body. Since the vibration suppressing device for a structure is configured with a control means for controlling the spring constant of the second spring portion so as to measure each of It is possible to obtain maximum vibration suppression effect. Moreover, this vibration suppression effect remains constant regardless of changes in the weight or rigidity of the building over time.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing a vibration suppression device for a structure, which is a first embodiment of the present invention, with Figure 1 being a front view showing its overall configuration, and Figure 2 including a control means. A schematic configuration diagram, FIG. 3 is a front view showing a vibration suppressing device for a structure according to the second embodiment, FIG. 4 is a diagram for explaining the invention in detail, and FIG. 5 is an inertial mass body and structure. FIG. 6 is a diagram showing the relationship of displacement with an object, and is a diagram showing the amplitude characteristics of the structure before and after installing the vibration suppression device. 10... Vibration suppression device, 11... Building (structure) 12... Support part, 13...
... Mass body, 15 ... Air spring (second spring part) 17 ... Horizontal deformation part (first spring part) 29.30 ... Sensor 31.32...
... Calculation means, 33... Difference calculation means (control means)

Claims (4)

[Claims] (1) A vibration suppressing device that is disposed at a predetermined position of a structure and includes an inertial mass and a support means that supports the inertial mass so that it can vibrate at the same vibration frequency as that of the structure. The supporting means includes a first spring portion having a fixed spring constant and a second spring portion having a variable spring constant, and the first and second spring portions are arranged in the same direction. The supporting means measures the actual vibration period of the structure and the actual vibration period of the inertial mass body, and measures the actual vibration period of the inertial mass body so as to match them. 1. A vibration suppressing device for a structure, comprising: a control means for controlling a spring constant of a second spring portion. (2) The vibration suppressing device for a structure according to claim 1, wherein the supporting means supports the inertial mass body so as to be able to vibrate freely along two directions. (3) The vibration suppressing device for a structure according to claim 1, wherein the control means increases the spring constant of the second spring portion when the amplitude of the inertial mass body exceeds a permissible range. . (4) The vibration suppressing device for a structure according to claim 1, 2 or 3, wherein the second spring portion is an air spring.