JPH047798B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention is a vibration damping device for buildings that suppresses the shaking of buildings due to earthquakes, etc., by installing a dynamic damper near the top of mid-to-high-rise buildings. , relates to a device that allows buildings to have a vibration damping function in a very natural manner.

<<Prior Art>> The Chiba Port Tower is a typical example of a recent vibration control system for a tower-like structure using a dynamic damper. This damping device is
Nikkei McGraw-Hill “Nikkei Architecture” 1986
As disclosed in detail on May 5th,
A dynamic damper designed to have a natural period equal to the first natural periodic vibration of the building is installed near the top of the tower-like structure. When a building vibrates at its first natural period, the damper system is also excited and vibrates at its own natural period. As a result, a part of the vibration energy of the building is absorbed as vibration energy of the damper system.

Originally, from the purpose of reducing vibration, this satisfies the purpose to a certain extent.

[Problems to be Solved by the Invention] However, with the above-mentioned conventional technology, when a building exhibits complex behavior, the response to the initial vibration rise, the beating phenomenon due to input waves near the natural period, and the building due to external force vibration It was not very effective in the forced vibration range.

According to the research conducted by the present inventors, the response of a building to input generated by an earthquake is as follows. After the input wave propagates to the building, vibrations in higher-order modes of 3rd order or higher occur first, then the 2nd mode vibrations, and the 1st mode vibrations occur after ten minutes after the input wave propagates. After a few seconds have passed.

If you design a dynamic damper only to match the first natural period of the building as in the past,
There is almost no damping effect on secondary and tertiary vibrations, and therefore it is impossible to suppress vibrations immediately after an earthquake is transmitted to a building.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to provide a vibration damping system for buildings using a dynamic damper that effectively acts on higher mode vibrations immediately after an earthquake is transmitted. Our goal is to provide the following.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present invention provides at least three resonance characteristics that match each of the first natural period, second natural period, third natural period, etc. of the building. We decided to install a dynamic damper with a vibrating mass point system near the top of the building, and a weight supported by an elastoplastic column at the top of the structure and a damper near the same horizontal plane that is integral with the base of the column. In accordance with the installed seismic motion input sensor and the transient characteristics of the natural periodic vibration that changes step by step from the initial natural periodic vibration of the earthquake motion, magnetic and a control device that selects the magnetic body at a position corresponding to the natural periodic vibration based on the output of the sensor and energizes the coil of the magnetic body, and controls the natural periodic vibration of the elastic-plastic column. The elastic-plastic column is restrained and released by the magnetic body at a position corresponding to the change in the natural periodic vibration, so as to cancel the vibration of the midway part that vibrates according to the transient characteristics. be.

<<Effect>> When earthquake waves are transmitted to a building, third-order mode or higher-order vibrations are first generated,
At this time, 3 in the above dynamic damper
The vibrating mass point system matched to the next natural period resonates, thereby absorbing the vibration energy of the building. When the vibration of the building changes to the second-order mode,
Another vibrating mass point system tuned to the secondary natural period resonates, and the vibration energy of the building is effectively absorbed. Finally, when moving to the first mode of vibration, 1
Yet another vibrating mass system that matches the next natural period resonates and absorbs vibrational energy.

Here, the problems of the prior art and the effects of the present invention will be explained again from a theoretical perspective.

When analyzing natural phenomena, it is a common method in modern science to make certain assumptions and substitutions to make the analysis easier without sacrificing accuracy.

Such substitutions are also often used in seismic engineering. However, even if these substitutions are correct for calculation purposes, there may naturally be cases where they do not result in a perfect simulation.

If we consider a skyscraper, the building is a perfect continuous elastic body. When analyzing how this high-rise building responds to input seismic waves from the ground,
Considering the concentrated mass on the floor of the building, we perform response calculations as a mass point system with the same period and damping coefficient as the building. Since the calculated value based on this replacement finally agrees well with the measured value, it can be said that this is a correct replacement.

However, in reality, seismic waves enter a building, which is a continuous elastic body, and the wave is converted into vibration within the building until the continuous elastic body moves enough to be replaced by a mass point system. These were revealed through experiments conducted by the present inventors.

When waves are transmitted from the bottom of the foundation to the top of the building,
Buildings begin to move from modes forced by the wavelengths generated during wave propagation. If the period is T, the height of the building is H, and the wave propagation velocity of the building is Vs, then T=H/Vs. Then, the movement gradually approaches the natural period of the building, and vibrations begin to occur at the first natural period of the building after about ten seconds. From this point on, the above-mentioned substitution as a mass point system is established (in the case of a mass point system, the first-order period is most easily stimulated,
Regarding the question of whether these phenomena can be simulated correctly by replacing them as a mass point system, although there are elements that can be simulated, it is possible to It turns out that it is not possible to simulate correctly until there is a movement that can be replaced with .

The present invention provides a vibration damping device using a dynamic damper that is adapted to these real phenomena that cannot be simulated and has a high initial vibration damping effect.

The dynamic damper for carrying out the present invention needs to be a dynamic damper that has properties that change from the form of high-order vibration generated from the propagation of an initial wave to a first-order system. Such a dynamic damper has the form of a multi-material system that produces cubic vibrations. Then, the first, second, and third natural periodic vibrations of the main body of the building, as well as the first, second, and third natural periods of the dynamic damper installed at the top of these vibrations, are calculated. The condition is that each vibration is equal.

First, when a building vibrates due to earthquake motion,
Waves propagate from the foundation to the top. This speed is fast (300 to 400 m/sec). There are two types of waves that propagate, longitudinal waves and transverse waves, and transverse waves are the element that causes horizontal displacement of buildings. The displacement of a building due to transverse waves is: ξn = Asin (ωT - κna) A: Amplitude due to wave ω: Natural angular velocity of the building, where f is period κ: Wave a: Distance between fulcrums Frequency: v = ω/2π Propagation speed: V=λ/(1/V) From the relationship λ=2π/κ=wavelength, the natural period and wavelength of the building are determined from the propagation speed and the height of the building, and a phase delay occurs due to propagation. The initial vibration mode is determined.

Therefore, it is ideal for a seismic damping device to be able to follow the movements of these structures.

Theoretically, buildings are said to be most mobile in the first mode, but they also have the property of being easy to move in the second and third higher modes. A damping device designed to be effective only on the first-order mode cannot track higher-order modes. Moreover, according to the response calculation of the mass system replacement, the damping set in the first mode is not effective against the initial wave and the wave with a sudden rise.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

Figure 1 shows the general structure of the building. 1 is a building, and the roof of the building has pillars 2 made of elastic-plastic steel.
-2 is erected, and a weight 3 is fixed to the top. The weight of the weight 3 is determined by the height and shape of the structure 1, but is approximately 15 to 30 tons. This weight 3 is configured to move back and forth and left and right due to the deflection of the support column 2-2.

In the middle of each pillar 2-2, there is an annular electromagnet 4 on top that surrounds the pillar, and an electromagnet 4 on the bottom.
The electromagnets 4 and 4a are fixed to the building 1. Furthermore, a seismic motion sensor 5 is provided at the same horizontal position as the base of the support column 2-2. This sensor 5 transmits data such as instantaneous acceleration, amplitude period, angular displacement, etc. to the control device 6.

FIG. 2 shows the relationship between the electromagnets 4, 4a and the control device 6.

Regarding the dynamic damper's tracking of the transition from the third-order mode to the first-order mode due to earthquake motion, the natural periodic frequency of the damper, that is, the shaking of the weight 3, is determined by the length of the damper's legs (here, the length of the support column 2-
2). Therefore, the electromagnet 4 is installed at a position corresponding to the vibration period of the initial third mode. In that case, the separation distance from the weight 3 to the electromagnet 4 is assumed to be l ₃ . Similarly, the position corresponding to the secondary mode
An electromagnet 4a is arranged at a location _l2 , and a height _l1 corresponding to the first mode is set to the height of the support column 2.

Then, the control device 6 compares the data of the sensor 5 and the vibration data of the preset tertiary mode,
At the time when they almost match, the energization to the electromagnet 4 is controlled, and the natural periodic vibration is changed so as to cancel the vibration of the midway part of the support 2 that vibrates according to the transient characteristics of the natural periodic vibration. The column is restrained and released by the electromagnet 4 located at the position corresponding to the position. When the vibration gradually shifts to the second-order mode, the control device 6 compares and analyzes the vibration data of the second-order mode and the data coming from the sensor 5, and energizes only the electromagnet 4a while leaving the electromagnet 4 open. This energized state is such that the weight 3 moves in the direction of canceling the vibration of the secondary mode.
The support column 2 is restrained and released by an electromagnet 4a.

In the primary mode, the electromagnets 4 and 4a are not energized.

In addition, the electromagnets 4 and 4a are fixed to the support column 2,
The material of the column 2 may be freely selected from a material having high elasticity and plasticity, and a magnetic material may be arranged around the outer circumference of the column corresponding to the electromagnets 4, 4a. Alternatively, it is also possible to provide electromagnets both on the pillar side and around it to accommodate more complex vibration modes.

<<Effects of the Invention>> As explained in detail above, according to the vibration damping device for a building according to the present invention, the damper having a weight supported by an elastoplastic column, a control device, and an earthquake input sensor control the damper. The elastoplastic strut, which is equipped with a magnetic material and supports a weight, vibrates in accordance with the transient characteristics of the natural periodic vibration, and responds to changes in the natural periodic vibration so as to cancel out the vibration of this halfway part. The elasto-plastic columns are restrained and released by the magnetic material at the position where the weight moves, and the direction of movement of the weight, the magnitude of the moving force, and the acceleration during movement are controlled. Therefore, it is possible to effectively absorb vibration energy even in the second mode and the third mode of vibration. Therefore, it has the effect of imparting seismic damping properties to the building very naturally immediately after the earthquake waves are transmitted.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the general structure, and FIG. 2 is an explanatory diagram for explaining the operation. 1... Building, 2... Support, 3... Weight, 4...
...electromagnet, 5...sensor, 6...control device.

Claims (1)

[Claims] 1. A weight supported by an elastoplastic column at the top of a building, a seismic motion input sensor installed near the same horizontal plane that is integral with the base of the column, and a natural period that changes in stages from the initial natural period of the earthquake motion. A magnetic body is selectively installed in advance in the vicinity of an appropriate height in the axial direction of the elastic-plastic column in accordance with the transient characteristics of vibration, and the magnetic body is located at a position corresponding to the natural periodic vibration according to the output of the sensor. and a control device for energizing the coil of the magnetic material, and for canceling the vibration of the middle part of the elastoplastic column that vibrates according to the transient characteristics of the natural periodic vibration. . A vibration control device for a building, characterized in that the elastic-plastic column is restrained and released by the magnetic body at a position corresponding to a change in the natural periodic vibration.