JPH0480184B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is designed to support a superstructure such as a building on a foundation, which is a substructure, so as to be able to swing freely, thereby reducing seismic energy transmitted from the ground to the superstructure. This invention relates to a damping mechanism that accelerates vibration damping in a seismic isolation structure that reduces vibration.

Prior Art As one of the earthquake-resistant structures of buildings, a plurality of isolators 1, 1... are installed in the upper structure 2 as shown in Fig. 4.
There is something that is inserted between the upper structure 2 and the lower structure 3 to support the upper structure 2. As shown in FIGS. 5 and 6, this isolator 1 has rigid plates 4, 4 made of steel plates, etc.
. . . thin elastic plates 5, 5 . . . made of natural rubber, neoprene rubber, etc. are alternately stacked vertically and fixed by adhesive. The isolator 1 has thin elastic plates 5, 5, . Therefore, the upper structure 2, which is a heavy object, is supported with good stability and its movement in the horizontal direction is regulated by a weak spring. 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 response acceleration of the building to input from the ground when an earthquake occurs.

However, if the upper structure 2 is supported only by the isolator 1, the following problem occurs because the horizontal spring force of the isolator 1 is small.

The first problem is that once the upper structure 2 begins to vibrate due to the action of seismic motion, the vibration amplitude will be lower than when the upper structure 2 is directly mounted and supported on the lower structure 3 without using the isolator 1. As the tremors grow larger, it takes longer for them 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 inappropriate as a seismic isolation structure for buildings.

The second problem is that if a building is also subjected to a lateral load such as the wind pressure of a typhoon, the superstructure 2 may shift in that direction, and the stability of the superstructure is not guaranteed.

In order to solve the first and second problems above,
The applicant proposed that an annular member made of an elastoplastic material such as a steel rod as shown in FIG. 6 as a damping mechanism, either alone as shown in FIG. 8 or in combination as shown in FIG. 11, was invented and filed earlier.
(Japanese Patent Application Laid-Open No. 59-217877 [Patent Application No. 58-93259], Japanese Patent Application Publication No. 60-258343 [Patent Application No. 114850-1989]) Both ends of this annular member 6 are connected to the upper structure 2 and the lower structure 3, respectively. When the upper structure 2 and the lower structure 3 move relative to each other in the horizontal direction due to earthquake motion, the annular member 6 deforms elastically and plastically as shown in FIG. 9 or 10, for example. The annular member 6 is made of an elastoplastic material and deforms with hysteresis characteristics as shown by the solid line A in FIG. 3 in response to the stress P.
Vibration energy is absorbed in an amount corresponding to the area surrounded by the hysteresis loop for each vibration period.

Due to the above-mentioned vibration energy absorption effect, the eighth
In the base isolation structure shown in Figure 1 or Figure 11, the amplitude when the upper structure 2 vibrates is smaller than that of the base isolation structure with only the isolator 1 shown in Figure 4, and the amplitude and acceleration after the vibration starts are attenuated. becomes extremely rapid.

In addition, the diameter and thickness of the annular member 6 deform elastically and plastically only when a horizontal stress of a magnitude necessary for seismic isolation is applied, and it hardly deforms under a small unidirectional load in the horizontal direction such as wind pressure of a typhoon. Since it is set to a value that does not cause deformation, a fixed effect of the upper structure on the lower structure can be obtained.

The combination type shown in FIG. 11 was invented to solve the disadvantage of the single type shown in FIG. 8, which is composed of only one annular member 6 and has a directional damping effect. be. In other words, as shown in FIG. 12, a plurality of annular members 6, 6... are combined in a petal shape to eliminate directionality and at the same time make it more compact, and are fixed to the upper structure 2 and the lower structure 3 in one place each. This makes installation easy.

Problems to be Solved by the Invention When the upper structure moves relative to the lower structure, the annular member absorbs vibration energy by deforming elastically and plastically with hysteresis characteristics as shown by the solid line A in Figure 3. are doing. In order to enhance this damping effect, it is preferable to combine materials with higher plasticity (viscosity). Moreover, if only plastic materials are used, they are likely to break when subjected to repeated deformation due to earthquakes, etc., and cannot maintain deformation following ability.

In other words, the reason why an elastoplastic material is used for the annular member is to have both the property of withstanding repeated deformation and the hysteresis property.If the annular member is made of a single material, there is a limit to increasing the hysteresis property. It was hot. What is required of the annular member as a damping mechanism is an energy absorption effect based on hysteresis characteristics, and elastoplastic properties are essentially unnecessary as long as they can withstand repeated deformation. In other words, conventional annular members made of elastoplastic materials cannot be said to have ideal characteristics.

Means for Solving the Problems The present invention provides a seismic isolation structure in which an upper structure is mounted and supported on a lower structure through an isolator formed by alternately stacking rigid plates and elastic plates. A damping mechanism for damping the relative movement in the horizontal direction with respect to the lower structure, which has a structure in which an elastic material holding a plastic material or an elastoplastic material is shaped into an annular shape, and one end of this annular member is attached to the upper structure, This is an elasto-plastic damping mechanism using a composite material, with the other end fixed to the lower structure.

Function In the elastic-plastic damping mechanism, the plastic material portion provides a large hysteresis characteristic, and at the same time, the elastic material or elastic-plastic material portion holds the plastic material portion to prevent breakage due to repeated deformation.

Embodiments Examples of the present invention will be described below with reference to the drawings.

In the first embodiment, as shown in FIG. 1, a composite material 9 is used in which a hollow portion of an elastoplastic material 7 such as a steel pipe having an annular cross section is filled with a plastic material 8 such as lead.

The second embodiment is a composite material 1 in which a plastic material 8 such as lead is filled into a hollow portion of an elastoplastic material 10 such as a square steel pipe having a rectangular cross section as shown in FIG.
1 is used.

These composite materials 9 and 11 are bent into an annular shape, for example, as shown in FIG. 7, singly as shown in FIG. 8, or in combination as shown in FIG.
Used as a damping mechanism.

In these cases, the hysteresis increases due to the plastic material 8 filled in the hollow portions of the elastic-plastic materials 7 and 10. When this was confirmed through experiments, the characteristics of the amount of deformation δ with respect to the stress P were as shown by the dotted line B in FIG. When this is compared with the conventional type A using a single elastic-plastic material, the surrounding area, that is, the amount of energy absorbed per vibration period is significantly larger.

Note that the elastic-plastic material 7, 10 serving as the core material of the composite material 9, 11 may be made of an elastic material such as spring steel. This is because it is sufficient to provide this portion with a deformation following ability for repeated deformation. Further, the cross-sectional shape of this portion may be any shape as long as it holds the plastic material 8. For example, it is also possible to form the composite material by using H-type steel or I-type steel as the core material and filling the recessed portions with a plastic material such as lead.

Furthermore, when the composite materials 9 and 11 are bent into an annular shape,
It is not necessary to make it a perfect circle, and the cross-sectional area, wall thickness, etc. may vary depending on the applied stress.

Effects of the Invention The present invention provides a seismic isolation structure using an isolator, in which an elastoplastic material or an elastic material is used as a core material as a damping mechanism, and a composite material in which plastic materials are superimposed so as to be held by the core material is bent into an annular shape. Since we have provided this product, we can provide a product with large hysteresis characteristics and a large damping effect. This allows the damping mechanism to be made smaller and easier to install. Furthermore, in the present invention, the energy breathing action is mainly shared by the elastic material part, and the deformation tracking function for repeated deformation is mainly shared by the elastoplastic or elastic material part, so the degree of freedom in design is increased and manufacturing is facilitated. .

[Brief explanation of the drawing]

1 and 2 are the first and second embodiments of the present invention, respectively.
FIG. 3 is a diagram showing a cross-sectional shape of a composite material showing an embodiment of the present invention, and FIG. 3 is a diagram showing a hysteresis characteristic of the damping mechanism of the present invention in comparison with a conventional example. Figure 4 is a front view showing an example of a conventional seismic isolation structure, Figures 5 and 6
The figures are a front view and a plan view of the isolator. 7 to 12 are diagrams showing conventional examples that are the premise of the present invention. FIG. 7 is a perspective view of an annular member, and FIG. 8 is an example in which the annular member shown in FIG. 7 is used alone. A front view of the seismic isolation structure, FIGS.
The figure is a front view of a seismic isolation structure showing an example of using the annular members shown in Figure 7 in combination, and Figure 12 is a front view of a base isolation structure using the annular members shown in Figure 7.
It is a perspective view which shows the combined state of the annular member in a figure. 1...Isolator, 2...Superstructure, 3...
Lower structure, 4... Rigid plate, 5... Elastic plate, 6...
Annular member, 7, 10... Elastoplastic material or elastic material, 8... Plastic material, 9, 11... Composite material.

Claims (1)

[Scope of Claims] 1. A seismic isolation structure in which an upper structure is mounted and supported on a lower structure through isolators formed by alternately stacking rigid plates and elastic plates, and the upper structure is horizontal to the lower structure. It is a damping mechanism that dampens relative motion in the direction, and has a structure in which an elastic material holding a plastic material or an elastoplastic material is shaped into an annular shape, one end of this annular member serves as an upper structure, and the other end serves as a lower structure. An elasto-plastic damping mechanism using a composite material that is fixed to the