JPH0477112B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides an insulation material that is interposed between a superstructure and a substructure, such as a building and its foundation, to reduce seismic energy transmitted from the substructure to the superstructure. This invention relates to a damping device used in seismic devices, etc.

<Prior art> As one of the earthquake-resistant structures of buildings, as shown in Fig. 3, isolators 5, which are multiple seismic isolation devices, are used.
1 and 51 are sandwiched between an upper structure 52 and a lower structure 53 to support the upper structure 52. This isolator 51 is made by vertically stacking rigid plates such as steel plates and thin elastic plates such as natural rubber alternately, and has large rigidity in the vertical direction, and a small horizontal spring due to shear deformation of the rubber in the horizontal direction. It has rigidity. Therefore, the heavy upper structure is supported with good stability, and its movement in the horizontal direction is regulated by weak springs. Such support increases the horizontal vibration period of the entire system of structures, making it greater than the period of the maximum energy component of the earthquake. Therefore, it is possible to reduce the acceleration of the building's response to input from an earthquake when an earthquake occurs.

However, if the upper structure 52 is supported only by the isolator 51, the isolator 51
Since the spring force in the horizontal direction of 1 is small, the following problem occurs.

The first problem is that once the upper structure 52 begins to vibrate due to the action of seismic motion, the vibration amplitude becomes larger than when the upper structure 52 is directly supported by the lower structure 53 without using the isolator 51. , it will take some time for the shaking to subside. In other words, even if physical safety is guaranteed, residents will remain in a psychologically unstable state for a long time, making it unsuitable for buildings.

The second problem is that when a lateral load such as a typhoon wind load is applied to a building, the upper structure 52
There is a risk that the upper structure 52 may be displaced, and the stability of the upper structure 52 cannot be guaranteed.

In order to solve these problems, recently a damping device consisting of a viscous damper that utilizes the viscous resistance of fluid has been interposed between the upper and lower structures of buildings, and the viscous resistance can be used to absorb vibration energy. Some proposals have been made to absorb the liquid (for example, Japanese Utility Model Publication No. 59-41218).

<Problems to be Solved by the Invention> By the way, in the design of the above-mentioned conventional viscous damper, the maximum possible displacement is greater than or equal to the amplitude (displacement of about 250 mm) of the largest earthquake acting on the building. design.

On the other hand, the viscous shear force F is F=ηV/d・S F = viscous shear force S = resistance plate shear area V=relative velocity d=distance between two surfaces η = viscosity coefficient (see Figure 2), and is proportional to the relative velocity V.

However, when buildings shake due to an earthquake,
Since the natural frequency of each building is constant, the vibration velocity of a large-amplitude earthquake will be greater than that of a small-amplitude earthquake. Therefore,
When designing a viscous damper to cope with large earthquakes, a viscous fluid with a small viscosity coefficient is used, but when such a viscous damper experiences a small-amplitude earthquake, which occurs most often, the relative velocity is small, so A large viscous shear force cannot be obtained, that is, vibration energy cannot be absorbed, and the building will sway for a long time. This creates psychological anxiety for residents.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a damping device that can effectively absorb vibration energy and exhibit a damping function both during small amplitude vibrations and large amplitude vibrations.

<Means for Solving the Problems> In order to achieve the above object, the damping device of the present invention includes a viscous damper that has one end attached to the upper structure and the other end attached to the lower structure and has a damping ability during vibrations of large amplitude. , comprising an upper holding cylinder fixed to the upper structure, a lower holding cylinder fixed to the lower structure, and a lead rod body tightly inserted inside the upper and lower holding cylinders, The gap between the tip and the tip of the lower holding cylinder is smaller than the inner diameter of the upper and lower holding cylinders, so that even if the upper structure vibrates with a small amplitude with respect to the lower structure, the rod will not undergo plastic shear deformation. The viscous damper and the elastoplastic damper are
It is characterized in that it is provided in parallel between the upper structure and the lower structure.

<Operation> When the superstructure vibrates slightly due to a small earthquake, the viscous damper has a small relative velocity,
Since the viscous shearing force is small, almost no energy can be absorbed, but in an elasto-plastic damper, the lead rod is restrained by the upper and lower holding cylinders, and almost no elastic bending deformation is possible. At the gap between
Due to the plastic shear deformation, small vibration energy is absorbed by the hysteresis effect in the plastic shear deformation region of this lead rod. Therefore, even if a small-amplitude earthquake occurs, the vibrations of the superstructure will attenuate in a very short time, and the time it takes for residents to stop feeling the vibrations after an earthquake occurs is extremely shortened.

On the other hand, when the superstructure vibrates greatly due to a large earthquake, the relative velocity in the viscous damper is high and the viscous resistance becomes large, and this viscous resistance absorbs the vibration energy and quickly damps the vibration of the superstructure. Note that at this time, the elastoplastic damper undergoes plastic destruction, but this poses no practical problem since earthquakes that cause such large vibrations are extremely rare.

The reason why the viscous damper and the elasto-plastic damper can be used independently depending on the magnitude of the amplitude is that the viscous damper and the elasto-plastic damper are provided in parallel between the upper structure and the lower structure. This is because

<Examples> The present invention will be described in detail below with reference to illustrated examples.

In Figure 1, 1 is an upper structure U and a lower structure D.
A viscous damper, 21, interposed approximately horizontally between
is an elastoplastic damper interposed between the upper structure U and the lower structure D.

The viscous damper 1 has a piston 3 slidably fitted into a cylinder 2, and the piston 3 is provided with an orifice 5. One end of a piston rod 6 projecting left and right from the piston 3 is connected to a bracket 7 by two pins perpendicular to each other.
This bracket 7 is fixed by a nut 10 to an anchor bolt 9 that passes through a mounting plate 8 embedded in the upper structure U. On the other hand, cylinder 2
The clevis 11 fixed to the left end of the bracket 1
It is pin connected to 2. This bracket 12 is fixed by a nut 16 to an anchor bolt 15 that passes through a mounting plate 13 buried in the lower structure D. The cylinder 2 is filled with a viscous fluid 14. Therefore, due to the movement of the piston 3 in the cylinder 2, the viscous fluid flows through the orifice 5 from the chamber on one side of the piston 3 to the chamber on the other side, and its viscous resistance causes the upper part to move against the lower structure D. It is designed to provide braking force against horizontal vibrations of structure U. Since the magnitude of this viscous resistance is determined by the magnitude of the relative velocity of the piston 3 with respect to the cylinder 2, this braking force will provide a large braking force against a large-amplitude earthquake.

On the other hand, the elastic-plastic damper 21 includes a cylindrical rod body 22 made of lead. The upper end of this rod 22 is inserted into a holding cylinder 23 fixed to the upper structure U so as to provide a space between it and the upper structure U. This space absorbs the volume change that occurs when the rod 22 is deformed. The holding cylinder 23 consists of a cylindrical part 23a and a flange part 23b, and this flange part 23b
is attached by a nut 26 to an anchor bolt 25 that passes through a mounting plate 24 embedded in the upper structure U. The tip of the cylindrical portion 23a widens toward the end, making it easier to insert the rod 22.
The lower part of the rod 22 is inserted into a holding cylinder 27. This holding cylinder 27 has exactly the same structure as the above-mentioned holding cylinder 23, and is fixed by a nut 31 to an anchor bolt 30 that passes through a mounting plate 29 buried in the lower structure D. Above lead rod 2
No. 2 has a large plastic region and a thick diameter, so it can withstand large external forces.

The gap between the opposing ends of the holding cylinder 23 and the holding cylinder 27 is made smaller than the inner diameter dimensions of both the holding cylinders 23 and 27. By doing so, the rod 22 inserted into both the cylinders 23 and 27 is restrained by both the holding cylinders 23 and 27, and is prevented from being bent and elastically deformed, and undergoes plastic shear deformation in the gap. A damping effect is obtained by plastic shear deformation against a small relative displacement between the upper structure U and the lower structure D. If the rod 22 is not inserted into the holding cylinders 23 and 27, or if the gap between the tips of the holding cylinders 23 and 27 is large, the displacement between the upper structure U and the lower structure D is small. Furthermore, since the rod 22 absorbs the displacement only through elastic bending deformation, that is, without plastic shear deformation, there is no damping effect on small amplitude vibrations.

Although not shown, an isolator made by vertically stacking rigid plates such as steel plates and thin elastic plates such as natural rubber or neoprene rubber is interposed between the lower structure D and the upper structure U. .

According to the damping device configured as described above, when an earthquake with a small amplitude occurs, almost no viscous resistance occurs because the relative speed of the piston 3 of the viscous damper 1 to the cylinder 2 is small, but the lead rod of the elastoplastic damper 21 22 undergoes plastic shear deformation, and the vibration energy is absorbed by the hysteresis effect caused by the plastic shear deformation. Therefore, when an earthquake with a small amplitude occurs, the vibration of the superstructure U is quickly damped by the hysteresis effect caused by the plastic deformation of the rod 22 of the elastic-plastic damper 21, and the shaking of the superstructure is quickly stopped. Stop. Therefore, the residents will not feel psychologically uneasy. Further, since the lead rod 22 has a large cross-sectional area and a short length, it provides a large braking force against small vibrations.

On the other hand, in the event of an earthquake with a large amplitude, the moving speed of the piston 3 of the viscous damper 1 increases, so the viscous resistance in the viscous damper 1 increases, providing a large damping force against the vibration of the superstructure U. , the vibrations of the upper structure U are quickly damped, and the upper structure U quickly stops. Note that in the case of this large amplitude vibration, the lead rod 22 of the elastoplastic damper 21 is destroyed because its deformability is small. However, since such large-amplitude earthquakes occur very infrequently, there is no practical problem even if the elastoplastic damper 21 is destroyed only when a large earthquake occurs.

In this way, for small amplitude vibrations, the elastic-plastic damper 21 is effectively used to absorb the vibration energy, and for large amplitude vibrations, the viscous damper 1 is effectively used to absorb the vibration energy. This is possible because the elastic-plastic damper 21 and the viscous damper 1 are provided in parallel between the upper structure U and the lower structure D. In addition, the elastic-plastic damper 21 can absorb energy from small amplitude vibrations by restraining the lead rod 22 with the holding tubes 23 and 27 to prevent elastic bending deformation. This is because the rod 22 undergoes plastic shear deformation even with small amplitudes since it is deformed at certain points.

<Effects of the Invention> As is clear from the above, the damping device of the present invention is made of a viscous damper that has a damping ability during large amplitude vibrations, and an elastoplastic material, and has a damping ability due to plastic shear deformation during small amplitude vibrations. Since the elasto-plastic damper with the Therefore, the superstructure can be quickly brought to a standstill in both large and small earthquakes.

Further, in the damping device of the present invention, in an elasto-plastic damper, the lead rod is restrained by the upper and lower holding cylinders to prevent bending and deformation, and the lead rod is restrained by the upper and lower holding cylinders in a gap between the opposing ends of the holding cylinders. Since the rod is made to undergo plastic shear deformation, even when a small amplitude vibration is applied, the rod undergoes plastic shear deformation,
Can absorb vibrational energy.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a damping device according to an embodiment of the present invention, FIG. 2 is a diagram illustrating viscous resistance, and FIG. 3 is a sectional view of a conventional seismic isolation device. 1... Viscous damper, 2... Cylinder, 3...
... Piston, 5 ... Orifice, 21 ... Elastoplastic damper, U ... Upper structure, D ... Lower structure.

Claims (1)

[Scope of Claims] 1. A viscous damper having one end attached to the upper structure and the other end attached to the lower structure and having a damping ability during vibrations of large amplitude; an upper holding cylinder fixed to the upper structure; and a viscous damper attached to the lower structure. It has a fixed lower holding cylinder and a lead rod closely inserted inside the upper and lower holding cylinders, and the gap between the tip of the upper holding cylinder and the tip of the lower holding cylinder is the upper and lower holding cylinder. an elasto-plastic damper smaller than the inner diameter of the holding cylinder so that the rod undergoes plastic shear deformation even if the upper structure vibrates with a small amplitude with respect to the lower structure; What is the above elastic-plastic damper?
A damping device characterized in that the damping device is provided in parallel between the upper structure and the lower structure.