JP2003021193A - Base isolation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a layered rubber group base isolation device having smooth load-resistant rigidity, a spindle-shaped hysteresis loop and ideal performance. SOLUTION: This layered rubber base isolation device provided with a lead core or a super plastic material core is obtained by forming the shape of the lead core built in the current layered rubber with a lead core to have the minimum area at a central part in the height direction and the maximum area in both ends in the vertical direction and to be continuously changed at an intermediate part thereof.

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

In order to protect a structure from a strong earthquake motion during a large earthquake, there are seismic isolation structures in which various seismic isolation devices are arranged between the ground and the structure to prevent the vibration of the ground from being directly transmitted. It has been put to practical use. INDUSTRIAL APPLICABILITY The present invention provides a highly practical seismic isolation device that dramatically improves and improves the performance of a seismic isolation device that has already been put into practical use in order to realize a higher-performance seismic isolation structure. It is a thing.

[Prior art]

A seismic isolation device for realizing a seismic isolation structure has both an isolator function capable of performing large horizontal deformation while supporting the weight of the structure and a damper function absorbing the vibration energy of the structure due to an earthquake. It is necessary to have it, and as a seismic isolation system that has been put to practical use so far, natural rubber laminated rubber + separate damper-,
There are laminated rubber-based seismic isolation systems such as laminated rubber with high damping and laminated rubber with lead core. In addition to this, in recent years, PTFE
(Teflon (registered trademark)) material and a stainless steel plate are combined, and a seismic isolation device for sliding bearings, and a seismic isolation device for rolling bearings using ball bearings and the like have been put into practical use.

Among these seismic isolation devices, "Lead core laminated rubber seismic isolation device" was invented and developed in New Zealand to be one that has been highly evaluated worldwide and has a lot of achievements.
There is. This device has lead cores functioning as dampers enclosed in one place in the plane center of the laminated rubber bearing as an isolator or in multiple places in the plane. An isolator that also has the necessary functions of a seismic isolation structure in one device.・ It is a damper-integrated seismic isolation device, and the combination of a lead core and laminated rubber allows the device performance = resilience characteristics to be adjusted quite freely. It has a high reputation both in Japan and overseas. Seismic isolation device.

[Problems to be Solved by the Invention]

As described above, the lead rubber laminated rubber seismic isolation device is a seismic isolation device having many advantages. However, in order to realize a higher performance seismic isolation structure, the following improvements are made. Have challenges to do. It should be noted that the higher-performance seismic isolation structure referred to here means that the seismic isolation effect (= response acceleration reduction effect) is high and that the seismic motion input strength that can ensure safety is as high as possible. It means a seismic isolation structure with high safety performance.

First, the first problem to be solved is the restoring force characteristic (shape of the history loop) of the conventional laminated rubber seismic isolation device with lead cores.
However, it has a very high unloading rigidity. As the performance of seismic isolation structure is improved, the shear elastic modulus Gr of rubber material is low in order to extend the seismic isolation period, and the diameter of the lead core tends to be large in order to obtain high damping performance. As this combination becomes stronger, the unloading rigidity tends to become higher and higher, and the unloading rigidity of the history loop of the same device is almost upright (= infinite rigidity) on the graph.

When the portion where the response displacement is reversed during the response vibration at the time of the earthquake = the starting point of the unloading history, the unloading rigidity of this history loop is very high. As a result of approaching the mode of the collapsed foundation fixed building, a large response acceleration is generated in this part. Due to the high rigidity of unloading, it is a great challenge to improve the performance of the seismic isolation structure that the seismic isolation effect is greatly impaired.

The second problem to be solved is the damping constant h-response displacement δ relationship. This is a common issue when using hysteresis type dampers, friction dampers, and sliding bearings, not limited to lead core laminated rubber, but as long as a damper with a constant yield strength is adopted, the damping constant h will increase as the deformation increases. We have a fate to decline.

This is because the damping constant h depends on the relationship of absorbed energy Δw / strain energy W of the hysteresis loop. The strain energy W increases in proportion to the square of the deformation δ, while the absorbed energy Δw yields. This is because the yield strength is constant and is proportional to the first power of δ. In terms of response performance, it is desirable that the damping constant h does not decrease as much as the displacement increases. Theoretically, this can be achieved by a viscous damping mechanism in which the damper displacement force increases as the response displacement amplitude increases. However, if a hysteresis damping mechanism that can hold the h-δ relationship at a constant value can be realized, it would be an idea that would upset common sense. It will be a term.

[0009] A third problem that can be solved with the laminated rubber seismic isolation device is "release of concentration of skewness" at the upper and lower ends of the laminated rubber. Although no one has recognized this problem as a technical problem because no one has considered it possible until now, it is a very large problem for improving the safety and reliability of laminated rubber.

That is, it is the edge portions of the upper and lower ends of the laminated rubber that are exposed to the most severe conditions when the laminated rubber is horizontally deformed during an earthquake. Since the largest local strain is concentrated on this corner due to vertical load and horizontal shear deformation, it is possible to dramatically improve the seismic safety performance of the laminated rubber if the strain concentration at the upper and lower ends can be released. .

[Means for Solving the Problems]

The present invention is a laminated rubber integrated with an isolator / damper called "laminated rubber containing lead core" or "laminated rubber containing superplastic material core" in which a superplastic metal material having the same function as lead is enclosed. By adopting a seismic isolation device and introducing a special device to the core shape, the above three problems can be solved at the same time. In the explanation of the basic mechanism, the lead core and the superplastic metal material core have the same function, and therefore the following explanation will be unified by the expression "lead core".

In the conventional laminated rubber bearings containing lead cores, it is an implicit precondition that the distribution of the laminated rubber rigidity in the height direction is always constant, and the rigidity has been aimed to be as uniform as possible. This is because if a portion of the laminated rubber having a low rigidity is present, the deformation is concentrated in that portion, which is expected to cause damage to the laminated rubber and become a weak point. Similarly, it has been assumed that the lead core has a constant cross-sectional shape, but this is also intended to prevent deformation from being concentrated on a part of the lead core.

In the present invention, the lead core, which has a constant cross-sectional area in the height direction up to now, has a small cross-sectional area at the central portion and a large cross-sectional area at the upper and lower end portions, and is continuously changed between them. , Solve the above three problems at the same time. That is, by utilizing the fact that the horizontal force acting on the horizontal section of the seismic isolation device is the same at any height position, the lead core cross-sectional area at the height center position is minimized and continuously changed and expanded toward the end. Thus, first, the deformation of the central portion of the lead core having the smallest cross section is advanced, and the yield of the lead core is gradually advanced and expanded from the central portion to the end portion. As a result, the resilience characteristics of this seismic isolation device increased gradually as the deformation of the seismic isolation device increased, from the seismic isolation device with a small lead core to the seismic isolation device with a large lead core.
The resilience characteristics will shift and change. In addition, even when unloading, the deformation gradually disappears from the part with a small lead core cross-sectional area.Therefore, the horizontal deformation decreases with the unloading of the horizontal load, and the unloading rigidity decreases, resulting in a smooth history. You will get a loop.

The shear deformation of the upper and lower end portions of the laminated rubber is delayed as compared with the deformation of the central portion, and the shear strain is suppressed to be small, so that the third problem described above is also satisfied. Further, as the lead core becomes larger in size as the deformation progresses, the same effect is obtained, so that the decrease in the damping constant h with the increase in the deformation becomes gradual, and the second problem can also be solved. As described above, the introduction of the “continuous change in core cross-sectional area” reduces the unloading rigidity of the restoring force characteristic history loop, improves the h-δ relationship, and relaxes the concentration of shear strain in the upper and lower ends of the laminated rubber. The effect of three birds with one stone occurs.

The basic idea of the solution of the present invention is as follows.
It can also be explained as follows. In all conventional laminated rubber seismic isolation devices, the height of the rubber is always constant, and the shear strain during horizontal deformation is always the same at any height of the device. It has been common sense. However, assuming the most ideal seismic isolation device, when the input seismic motion is not so strong, the horizontal deformation that occurs is small, so it is preferable that the resistance of the lead core and damper that bear the damping performance is low. It is sufficient for itself to have a small area and a low height. As the input seismic motion becomes stronger, the amount of horizontal deformation that occurs becomes larger. Therefore, it is necessary that the laminated rubber be large and the rubber height be high, and that the damping performance and the yield strength be high.

Therefore, originally, it is ideal that the size of both the damper (= lead core) and the isolator (= laminated rubber) is changed according to the strength of the input seismic motion. This is a seismic isolation device that exhibits the same effects and actions as a device, even though it is a device, and the size of the device is gradually replaced with a larger one according to the strength of the input seismic motion. In other words, a single seismic isolation device can exhibit innumerable device performance of an appropriate size according to the earthquake motion input.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described below with reference to the drawings showing an embodiment. FIG. 1 (1) is a cross-sectional configuration diagram of a conventional lead-core-containing laminated rubber seismic isolation device. Laminated rubber body by laminating a large number of thin rubber layers 7 and steel plates (inner steel plate 6) (the whole seismic isolation device 3)
Are formed, and lead (lead core 8) having a purity of 99.9% or more is filled and press-fitted into the hole at the center thereof (as an example). That is, a plastic material core (lead core 8) made of a rod-shaped superplastic metal (here, lead) that is fitted through the laminated rubber body 3 is formed in the central portion of the laminated rubber body 3 in the plane. The shape of the lead core 8 is
Here, a conventional type having the same cross-sectional area over the entire height is shown. Usually, a cylindrical shape is adopted. The lead core is sealed in the rubber and the steel plate, and the action of the vertical load keeps the lead and the rubber / steel plate in close contact with each other.

When a horizontal force is applied during an earthquake, the laminated rubber body 3 is sheared and deformed in the horizontal direction, as shown in FIG. 1 (2).
Due to the shear deformation of the laminated rubber body 3, the lead core 8 is also forced to undergo horizontal shear deformation. At this time, the horizontal restoring force characteristic of the laminated rubber body 3 shows a substantially linear elastic rigidity up to a shear strain γ = 250% when the rubber material is natural rubber, as shown in FIG. After that, gradually showed a tendency to harden,
It is a general property that rupture occurs around γ ≈ 400%.

On the other hand, the resistance development = restoring force characteristic of the lead core 8 forced to undergo horizontal shear deformation due to horizontal deformation of the laminated rubber body 3 first shows a high initial rigidity as shown in FIG. The rigidity gradually decreases, and when the yield shear strength of lead is reached, a plastic flow occurs. The characteristic of lead is that when the horizontal force is stopped, the deformation stops at that position and the resistance force disappears. That is, the unloading rigidity is almost vertical (= infinite rigidity), and residual displacement remains at that position.

The restoring force characteristics of the laminated rubber containing lead core are shown in FIG.
The almost elastic restoring force characteristics of the laminated rubber of (1) and FIG. 2 (2)
This is a combination of the plastic properties of lead, and a clean, almost bilinear type hysteresis loop as shown in FIG. 2C is obtained. At this time, since the rubber area and lead core area of the conventional lead core-containing laminated rubber are the same at any height position, horizontal shear strain of the same level and uniform over the entire height of the device is obtained in any horizontal deformation state. Degree has occurred.
This is a principle and a major precondition that all conventional laminated rubber seismic isolation devices take as a natural condition, but here is an important point of the present invention.

The greatest advantage of the laminated rubber containing the lead core is that the restoring force characteristic can be adjusted to some extent. That is, as shown in FIG. 3A, the horizontal rigidity of the laminated rubber body can be adjusted by adjusting the shear elastic modulus of the rubber material of the laminated rubber body, the diameter of the rubber layer, the layer thickness, and the number of layers. As shown in FIG. 3 (2), the yield strength determined by the resistance of the lead core can be adjusted by changing the diameter of the lead core. By combining these two, as shown in Fig. 3 (3), the yield strength and horizontal rigidity (second rigidity) of the seismic isolation device can be set quite freely, and the resistance level of the device, energy absorption performance, The deformation performance can be adjusted.

However, in any of the restoring force characteristics, only the unloading rigidity was very high, and its adjustment was impossible. In the design of laminated rubber with a lead core in recent years, in order to improve the performance of seismic isolation structures, the rubber rigidity of the laminated rubber is reduced to achieve a longer period, and the diameter of the lead core is increased to increase the energy absorption performance. Tends to increase. As a result, the resistance of the lead core becomes large and the restoring force of the laminated rubber becomes weak, so that the unloading rigidity shows a restoring force characteristic that is closer to vertical, and as a result, higher modes are easily induced. However, the response acceleration of the upper structure may be increased. Equipment design aimed at improving the performance of seismic isolation structures has the opposite effect, and is a limiting condition that prevents performance enhancement.

In order to solve the acceleration excitation problem due to the higher-order mode, it is necessary to improve the seismic isolation device to have a restoring force characteristic having a gradual unloading rigidity. However, a hysteresis type damper and a slip / friction type damper are required. Has been recognized as an unsolvable issue. In order to solve this problem, according to the present invention, as shown in FIG. 4, the area of the lead core 8 (the cross-sectional area in the plane direction of the laminated rubber body) is set at the height center portion (the thickness direction center of the laminated rubber body 3). Part), the maximum at both upper and lower ends, and the middle thereof are continuously changed. The area of the lead core 8 is changed so that the horizontal resistance of the lead core 8 is at the height position (position in the thickness direction of the laminated rubber body 3).
By virtue of this, the principle of horizontal shear strain, which was conventionally generated uniformly over the entire height, was broken. That is, since the area of the lead core 8 is the smallest and the resistance is the lowest in the vicinity of the central portion of the height, horizontal deformation precedes and the horizontal resistance gradually increases as the deformation progresses. The yield region of the core 8 is expanded from the center to the upper and lower ends.

Even at the time of unloading, since the lead core area is the smallest and the rubber area is the largest at the center position of the height of the device, the shearing deformation of lead is easily released by the restoring force of the rubber, and the lead core area is small Since the deformation gradually disappears, the horizontal deformation decreases with the unloading of the horizontal load, and as a result, the spindle-type spindle having smooth unloading rigidity as illustrated in 21 of FIG. A history loop will be obtained. In addition, the shear deformation of the laminated rubber upper and lower ends lags behind the deformation of the central part, and the shear strain is suppressed to a small level. The problem of strain concentration will be greatly improved.

In order to show this effect concretely and quantitatively,
The resilience characteristics of (a) a laminated rubber having a conventional lead core and (b) a laminated rubber having a lead core of the present invention are compared. As an example, as shown in FIGS. 5A and 5B, the laminated rubber diameter is 1,000 mmφ, the rubber layer is 8 mm × 30 layers, and the total rubber layer thickness = 2.
40 mm, the rubber material has a shear elastic modulus Gr = 5.5 kg / cm2. The lead core diameter is (a) conventional type = 200 mmφ uniform, the present invention type has a central minimum diameter = 100 mmφ, upper and lower end maximum diameter = 3
00mmφ.

FIG. 6 shows the restoring force characteristics (design history loop) of both. The solid line loop 20 is the loop of the device of the present invention, and the broken line loop 10 is the loop of the conventional device. In Figure 6,
A history loop up to shear strain γ = 250% and horizontal deformation d = 60 cm of the conventional device is overwritten.

In order to more clearly understand the difference between the two, the hysteresis loop up to shear strain γ = 100% and horizontal deformation d = 24 cm was enlarged and compared to compare the conventional device of FIG. 7 and FIG. The device of the present invention.

By comparing the two, the difference between the two devices and the features of the device of the present invention can be clearly understood. That is, the conventional device
The horizontal rigidity provided by the rubber layer is the second rigidity, and the bilinear loop that combines the rigid-plastic history provided by the lead core has a very high unloading rigidity 11. The history loop of the invented device does not have a constant second rigidity, and the unloading rigidity 21 also draws a gentle curve, and shows a smooth spindle-shaped history loop shape like a viscoelastic loop as a whole. .

The mechanism of this history loop expression can be explained as follows. In the conventional device, the shear strain of the rubber and the shear strain of the lead core proceed uniformly with the same strain at any position in the height direction. On the other hand, in the device of the present invention, the closer the height is to the central part, the smaller the area of the lead core is and the lower the resistance force is. That is, first, the shear strain of the central part with low horizontal resistance progresses, and the resistance shear stress of lead increases as the shear strain progresses, so the strain gradually increases toward the outside (upper and lower ends). I will do it. As a result, the resistance force exerted by the lead core as a whole gradually increases from the low resistance force of the central core to the resistance force of the large cross-section lead cores at the upper and lower ends at a small strain, resulting in a smooth rising curve. Therefore, it does not immediately converge to a constant yield strength unlike conventional devices. This is the reason why the rising skeleton curve draws a smooth curve.

Similarly, in the unloading history as well, the strain is gradually removed from the central portion where the strain is most advanced, the rubber restoring force is the maximum and the lead resistance is the minimum, so that the strain is gradually removed. A load curve will be drawn, and it will not become a simple rigid-plastic type loop. This is a mechanism that develops a spindle-shaped hysteresis loop shape like a viscoelastic material while it is a hysteresis loop based on the plastic history of metal.

FIG. 9 shows the seismic isolation device when the horizontal deformation progresses from zero to the average shear strain γ ave = 250% (the horizontal strain d divided by the total rubber height Tr, the average strain γ ave = d / Tr). The deformation | transformation state (horizontal deformation mode) of each part height position is shown. It has been shown that the rate of deformation near the central portion is large during small deformation, and gradually progresses to a uniform deformed shape as the amount of deformation increases.

FIG. 10 shows the state of evolution of the skewness at each height position in the deformed state. The value of the shear strain γ at the center of the figure represents the above-mentioned average strain γ ave.
For example, when the overall average skewness γave = 200%, the skewness at the center of the device has advanced to about 250%, but the skewness at the upper and lower ends is about γ = 130% (upper and lower ends in conventional equipment). It can be seen that the distortion of the part remains 200%). As is apparent from FIG. 10, the skewness distribution of the upper and lower end portions of the laminated rubber, which is the most severe strain area in the ordinary laminated rubber, is greatly relaxed, and the safety of the laminated rubber is improved and the reliability against damage is improved. It can be seen that it has contributed significantly to

FIG. 11 shows the damping constants of the hysteresis loops of the conventional type and the device of the present invention shown in FIGS. 6 and 7 and 8 when the shear strain γ = 50% (horizontal deformation amount d = 12 cm). The horizontal deformation and the rate of change of the damping constant h are shown with the value as a reference value = 1. With conventional equipment, shear strain γ = 250%
However, with the device of the present invention, it is about 60%.
It is shown that the decrease of the damping constant with the increase of horizontal deformation is moderate. This shows that the second problem is also greatly improved.

FIG. 12 shows the same rate of change of the damping constant h as in FIG. 11 when the combination of the diameters of the central part and the end part of the lead core of the device of the present invention is changed. The larger the difference between the lead core central diameter dpc and the end diameter dpe (the smaller the value of Cdp = dpc / dpe) is, the smaller the damping constant h becomes.
That is, the smaller the diameter at the center of height is, the more h
, The effect of the present invention is great. 12
Dpc = 200 mm, dpe = 300 mm, that is, Cdp = 0.67,
When the area ratio = 0.44, the effect of the present invention is sufficiently recognized, but when the difference in diameter is reduced, the difference from the conventional device gradually disappears. From this, the condition that "the cross-sectional area of the central portion of the lead core is 50% or less of the end cross-sectional area" described in claim 4 is determined as a region where the effect of the present invention is sufficiently exhibited.

In the above description, as described in the eleventh paragraph, the expression "lead core" has been used as the damper function incorporated in the laminated rubber, but any material having a large energy absorption performance and a large plastic deformation capacity can be used. So there is no reason to limit it to lead. Considering the recent situation in which the pollution problem of lead, which is a heavy metal, has been pointed out, materials other than lead should be adopted rather. In the present invention, among the materials known so far, as a result of examining materials having superplastic material characteristics at room temperature, it was found that the materials shown in Table 1 can be adopted. The materials shown in Table 2 are also known as superplastic metals, but since they cannot have superplastic properties unless they are at a considerably high temperature, they are regarded as "impossible" as a material for the present invention. The "superplastic material core" used as the core material for the built-in damper in claim 5 of the present invention is shown in Table 1, and the non-adopted materials are shown in Table 2.

[Table 1]

[Table 2]

Next, a specific method of manufacturing the seismic isolation device of the present invention will be described. In the device of the present invention shown in FIG. 4 and FIG. 5 (b), in order to reliably fill the core of lead or superplastic material, the filling degree and the laminated rubber of the portion where the core area is the minimum at the height center position are ensured. In order to ensure that the body holds the core, it is conceivable to use a thick steel plate (reinforcing steel plate) in the central portion. The cross-sectional configuration diagram is shown in FIG. That is, in FIG. 13, the superplastic metal (usually lead) that serves as the core is normally press-fitted in two parts from both the upper end and the lower end of the laminated rubber body. As a result, the core material has a fault in the center =
Although the discontinuous weak points are likely to occur, the thick steel plate at the center and the central inner shim 61 (reinforcing steel plate) serve to protect the weak points at the fault.

As a method of realizing this cross-sectional structure more easily, as shown in FIG. 14, the core diameter of the lead core or superplastic material incorporated in the apparatus is linearly changed,
That is, a laminated rubber bearing having a core of lead or superplastic material having a truncated cone shape is prepared. Although the symmetry in shape is broken, the device performance can be the same as that of the device according to claims 1 to 5. This is claim 6.

A seventh aspect of the present invention is to set two laminated rubber bearings each having a core of lead or superplastic material having a truncated cone-shaped core shape shown in the sixth and FIG. By bolting, a device having symmetry can be easily constructed. The procedure is shown in FIG.

A laminated rubber bearing 2 having a core of lead or superplastic material having a truncated cone shape shown in FIG.
The body is set as a set and the flange side having the larger diameter is bolted. The core shape is opposite to that of FIG. 15, but the expression performance and the restoring force characteristic are the same as those of the apparatus of FIG. However,
In this device, the deformation of both ends of the device first proceeds. Therefore, since the core portion having a large amount of heat generation due to the progress of deformation is divided into two, there is an advantage that a temperature rise due to heat generation is suppressed and a decrease in yield strength due to a temperature rise becomes small. The shape is shown in FIG.

In order to confirm the effect of the seismic isolation device of the present invention, FIGS. 17 and 18 show an example of a trial design of an 8-story seismic isolated building, and a comparison of seismic isolation effects by seismic response analysis. . FIG. 17 shows the maximum response acceleration of each floor of a seismic isolated building employing the conventional seismic isolation device, and FIG. 18 shows the maximum response acceleration of a seismic isolated building employing the seismic isolation device of the present invention. The adopted input seismic motion is common to both, and is a case where a very strong seismic motion with a maximum input acceleration of 400 to 1000 gal (cm / sec ² ) and a maximum input speed of 100 to 165 kine (cm / s) is applied. The horizontal axis is the strength of acceleration, and the vertical axis is M for the ground surface, 1 for the first floor of the building, 2 for the building
The number of floors is expressed as the floor of the floor. The seismic isolation device is located between the ground surface and the floor on the first floor. In the conventional seismic isolation system shown in FIG. 17, an acceleration of about 200 gal is generated on each floor, and the R floor on the rooftop reaches an acceleration of 300 gal or more. On the other hand, in the building employing the seismic isolation device of the present invention shown in FIG. 18, the response acceleration has almost no variation with respect to any seismic motion input, and the response acceleration is about 100 gal from the first floor to the roof R floor. It can be seen that the base-isolated building, which is controlled by the acceleration and which employs the device of the present invention, exhibits an extremely high seismic isolation effect. This effect is also obtained in the configuration of FIG.
The same applies to the configuration shown in FIG.

Compared with a hysteresis damping type seismic isolation device using a metal such as lead, a viscous damping type seismic isolation device using a viscous fluid as a damping device has a seismic isolation effect regardless of the magnitude of input acceleration. It has a high feature (= high response acceleration suppression effect). A conventional seismic isolation device having a lead core with a uniform thickness embedded in the center shows a ballinian hysteresis loop peculiar to hysteresis damping, but the lead core of the present invention has a cross-sectional area in the plane direction of the laminated rubber body. It is not uniform in the vertical direction, and the portion with a small cross-sectional area in the plane direction facilitates deformation of the laminated rubber body for small input acceleration, and the portion with a gradually larger cross-sectional area has stronger resistance to strong input. The seismic isolation effect is enhanced by exerting the force and by exerting the resistance force of the same pattern as that of the viscous damping type damping device as a whole.

It is preferable that the sectional area of the plastic material core in the plane direction of the laminated rubber body continuously and monotonically increases from the portion showing the minimum value to the portion showing the maximum value. The examples of FIGS. 13 to 16 all satisfy this condition. With such a configuration, the boundary surface between the laminated rubber body and the core is smooth, so that the work of press-fitting lead or a superplastic material becomes easy. Further, when stress due to an earthquake is applied, the amount of deformation of each part of the laminated rubber body does not change significantly, and there is an effect that an unreasonable force is not applied to the laminated rubber body.

[0043]

[Effect of the Invention] The laminated rubber seismic isolation device with lead core was developed in New Zealand in the late 1970s.
It has been highly acclaimed worldwide in advanced countries with seismic design such as Japan and Italy, and is currently the world's most proven seismic isolation device. The present invention solves the important problems remaining in this excellent seismic isolation device and transforms it into a nearly perfect seismic isolation device that has never existed before. The features and main effects of the present invention are summarized as follows. The conventional laminated rubber with lead core has a bilinear hysteresis loop, and its second rigidity and yield strength can be adjusted quite freely. However, there is a drawback that the unloading rigidity is extremely high and cannot be adjusted, and the high unloading rigidity excites a resonance phenomenon of a higher mode to generate a high response acceleration. INDUSTRIAL APPLICABILITY The present invention enables the unloading rigidity to be arbitrarily relaxed, and has a smooth spindle-shaped hysteresis as if it is a viscous material or a viscoelastic material despite the hysteresis damping mechanism. I realized the loop. Since it is not a viscous or viscoelastic material, it does not have the disadvantages of viscous or viscoelastic materials such as temperature dependence and speed dependence. A hysteresis damping mechanism with viscous / viscoelastic spindle-shaped loops is an epoch-making one that has never existed before. The loose unloading rigidity and the smooth spindle-type hysteresis loop provide the excellent response acceleration suppression effect of an ideal seismic isolation building with a viscous damping mechanism, and a high seismic isolation effect.
As is clear from the comparison between FIG. 17 and FIG. 18, the seismic response acceleration of the base-isolated building by the device of the present invention is better suppressed over all floors than the conventional device. Despite the hysteretic damping mechanism, the decrease in damping constant with increasing response deformation is small, and a large response suppression effect against strong seismic input and high damping performance can be expected. It has a spindle-shaped hysteresis loop shape like a viscous or viscoelastic material, but since it is not a viscous / viscoelastic material, it does not have the disadvantages of viscous (elastic) materials such as temperature dependence and speed dependence. . In the laminated rubber seismic isolation device, the largest local strain occurs at the upper and lower ends, but in the device of the present invention, the shear strain during earthquakes at the upper and lower ends thereof is suppressed, and therefore safety against fracture is high. As a result, the safety and reliability of the seismic isolation device as a whole has dramatically increased. As is clear from the comparison between FIG. 7 and FIG. 8, the hysteresis loop shape becomes a spindle loop, and the displacement amount at the position where the resistance force is zero on the hysteresis loop becomes small, so the residual displacement amount remaining after the earthquake becomes small. . As described above, the present invention realizes an almost perfect ideal seismic isolation device that has never been realized.

[Brief description of drawings]

[Fig. 1] Conventional laminated core seismic isolation device with lead core (1) Cross-section diagram (normal) (2) Deformation cross section during earthquake

FIG. 2 is an explanatory view of restoring force characteristics of a conventional lead core-containing laminated rubber (1) Horizontal restoring force characteristics of natural rubber-based laminated rubber body (2) Horizontal restoring force of lead core in lead core-containing laminated rubber Characteristics (3) Horizontal restoring force characteristics of laminated rubber with lead core =
(1) + (2)

FIG. 3 is an explanatory diagram of a method for adjusting the restoring force characteristic of a conventional laminated rubber containing a lead core (1) Adjustment of restoring force characteristic by rubber rigidity (2) Adjustment of restoring force characteristic (yield proof strength) by lead core (3) Lead Changes in horizontal restoring force characteristics of laminated rubber with core

FIG. 4 is an explanatory view of a core shape and a sectional configuration of a laminated rubber seismic isolation device containing a lead core (superplastic material core) of the present invention.

FIG. 5: Device design example of laminated rubber containing lead core for comparing restoring force characteristics (a) Conventional lead core seismic isolation device (b) Present invention type lead core seismic isolation device

FIG. 6 is a comparison of restoring force characteristics of the apparatus of FIG. 5 (γ ≦ 250%).
Illustration

FIG. 7 (a) Comparison of restoring force characteristics of the device (γ ≦ 10
0% enlargement) Restoring force characteristic history loop explanation diagram of conventional lead core seismic isolation device

FIG. 8 (b) Comparison of restoring force characteristics of the device (γ ≦ 10
0% enlarged view) Explanatory diagram of restoring force characteristic history loop of the present invention lead core type seismic isolation device

FIG. 9 is an explanatory view of the horizontal deformation mode shape in the height direction of the seismic isolation device of the present invention.

FIG. 10 is an explanatory view of horizontal shear strain distribution in the height direction of the rubber layer of the seismic isolation device of the present invention.

FIG. 11 is an explanatory diagram for comparing the rate of change of the damping constant h on the h-δ curve.

FIG. 12 is an explanatory diagram for comparing the rate of change of the damping constant h on the h-δ curve (when the rate of change of the lead core diameter is changed).

FIG. 13 is a sectional view of the seismic isolation device of the present invention in which the inner steel plate in the central portion is thickened to ensure filling of the core and holding of the core in the central portion.

FIG. 14 is a sectional view of a seismic isolation device in which the core shape is a truncated cone shape in which one has a large diameter and the other has a small diameter.

FIG. 15 is a cross-sectional view of a method for constructing this seismic isolation device by bolting two laminated rubber bearings having a truncated cone core.

FIG. 16: Same method as above. However, by reversing the core shape,
Sectional view when the central core is large and the end core diameter is small

[Fig. 17] Seismic isolation effect of a seismic isolated building that employs conventional seismic isolation devices (maximum response acceleration during a large earthquake)

FIG. 18: Seismic isolation effect of a seismic isolated building that employs the seismic isolation device of the present invention (maximum response acceleration diagram during a large earthquake)

[Explanation of symbols]

1 Upper building side body 2 Lower foundation 3 Whole seismic isolation device (laminated rubber body) 4 Flange plate 5 Outer steel plate (outer shim) 6 Inner steel plate (inner shim) 7 Rubber layer 8 Lead core (plastic material core) 10 Conventional Type hysteresis loop of laminated rubber with lead core (conventional seismic isolation device) 11 Unloaded stiffness curve of conventional seismic isolation device 14 Damping constant change rate of conventional seismic isolation device (ratio of damping constant to γ = 50% ) 20 Restoring force history loop of the seismic isolation device of the present invention 21 Unloading rigidity curve of the seismic isolation device of the present invention 22 Deformation mode during earthquake of the seismic isolation device of the present invention (horizontal displacement distribution) 23 Seismic strain mode (horizontal shear strain distribution in the height direction) 24 Damping coefficient change rate of the seismic isolation apparatus of the present invention (ratio of damping coefficient to γ = 50%) 41 Central flange 61 for connection Central inner steel plate (center inner shim) )

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukihiro Nishimura             38-1-515 Kamiofutomi, Sayama City, Saitama Prefecture F term (reference) 3J048 AA02 AC06 AD05 BA08 BD08                       DA01 EA38

Claims (10)

[Claims] 1. A laminated rubber body formed by alternately laminating and fixing a rubber layer and a steel plate, and a rod-shaped superplastic metal fitted through the laminated rubber body at the center of the plane of the laminated rubber body. And a plastic material core, the cross-sectional area in the plane direction of the laminated rubber body of the plastic material core is the smallest in the thickness direction central portion of the laminated rubber body, continuous as it approaches both ends in the thickness direction. A seismic isolation device characterized in that it is formed to be large. 2. The seismic isolation device according to claim 1, wherein the laminated rubber body of the plastic material core has a circular cross-sectional shape in a plane direction. 3. The seismic isolation device according to claim 1, wherein the cross-sectional shape of the laminated rubber body of the plastic material core in the plane direction is rectangular. 4. The seismic isolation device according to claim 1, wherein the minimum value of the cross-sectional area of the plastic material core in the plane direction of the laminated rubber body is 1/2 or less of the maximum value of the cross-sectional area. Seismic isolation device. 5. The seismic isolation device according to claim 1, wherein the plastic material core includes a Bi—In alloy, a Bi—Sn alloy, a Cd—Zn alloy, and P.
b-Sn alloy, Sn-Bi alloy, Sn-Pb alloy, Zn
-A seismic isolation device, which is made of any one kind of superplastic metal material of Al alloy. 6. A laminated rubber body, in which rubber layers and steel plates are alternately laminated and fixed, and a rod-shaped superplastic metal fitted through the laminated rubber body at the center of the plane of the laminated rubber body. And a plastic material core, the cross-sectional area in the plane direction of the laminated rubber body of the plastic material core,
The seismic isolation device is characterized in that one end portion in the thickness direction is the largest and is formed continuously smaller toward the other end portion. 7. A laminated rubber body formed by alternately laminating and fixing a rubber layer and a steel plate, and a rod-shaped superplastic metal fitted through the laminated rubber body at the center of the plane of the laminated rubber body. And a plastic material core, the cross-sectional area in the plane direction of the laminated rubber body of the plastic material core,
A seismic isolation device in which one end in the thickness direction is the largest, and the seismic isolation device is formed continuously smaller toward the other end. A seismic isolation device characterized in that its ends are opposed to each other and integrated. 8. A laminated rubber body formed by alternately laminating and fixing a rubber layer and a steel plate, and a rod-shaped superplastic metal fitted through the laminated rubber body at the center of the plane of the laminated rubber body. And a plastic material core, the cross-sectional area in the plane direction of the laminated rubber body of the plastic material core is the smallest in the thickness direction central portion of the laminated rubber body, continuous as it approaches both ends in the thickness direction. A seismic isolation device which is formed to be large in size, and which is provided with a reinforcing steel plate having a plate thickness thicker than the steel plate in the central portion in the thickness direction. 9. A laminated rubber body, in which rubber layers and steel plates are alternately laminated and fixed, and a rod-shaped superplastic metal fitted through the laminated rubber body at the center of the plane of the laminated rubber body. A seismic isolation device, comprising: a plastic material core, wherein a cross-sectional area of the plastic material core in a plane direction of the laminated rubber body is not uniform when viewed in a thickness direction of the laminated rubber body. 10. A laminated rubber body, in which rubber layers and steel plates are alternately laminated and fixed, and a rod-shaped superplastic metal fitted through the laminated rubber body at a plane central portion of the laminated rubber body. And a plastic material core, the cross-sectional area in the plane direction of the laminated rubber body of the plastic material core is not uniform when viewed in the thickness direction of the laminated rubber body, the cross-sectional area in the plane direction of the laminated rubber body is , A seismic isolation device characterized by monotonically decreasing or monotonically increasing from the portion showing the minimum value to the portion showing the maximum value.