JP2007139115A - Laminated rubber bearing with plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plug-filled laminated rubber bearing which is filled with e.g., a metal plug, at the center of a laminated rubber, and has a function of suppressing the temperature rise of the plug due to repetitive horizontal deformation. <P>SOLUTION: The plug-filled laminated rubber bearing 1 comprises the laminated rubber 2, flanges 3 integrated with the upper and lower parts thereof and joined to an upper structure and a lower structure, and a the metal plug 3 arranged at the center or its vicinity on the plane of the laminated rubber. The low-melting-point metal plug 4 is formed with a recessed portion therearound on the side of the laminated rubber 2. It is put at its peripheral face in close contact with the laminated rubber 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated rubber bearing with a plug having a function of suppressing a temperature rise of the plug due to repeated horizontal deformation in a laminated rubber bearing with a plug in which, for example, a lead plug is sealed at the center of the laminated rubber. .

  Laminated rubber bearings with lead are manufactured by enclosing a cylindrical lead plug in the center of laminated rubber made by laminating steel and rubber. When the laminated rubber is deformed horizontally, the lead plug undergoes shear deformation and yields. It has the function of converting vibration energy at the time of an earthquake into heat energy and consuming it.

  The lead plug generates heat by converting most of vibration energy into heat energy at the time of yielding, and rises to 30 to 60 ° C. due to repeated deformation due to one earthquake. On the other hand, it has the property of recrystallizing at normal temperature from the softened state while the vibration is stopped, that is, while the deformation is paused, and consumes the vibration energy even if the deformation is repeated after the vibration stops. There is a feature not available in steel, etc. that can demonstrate its capabilities. From this characteristic, it can be said that it is reasonable to use lead as a damper together with laminated rubber against vibration that can stop deformation.

  For the seismic ground motion for design used in the design of conventional seismic isolation buildings, the temperature rise of the lead plug is lower than 100 ° C, so the lead plug softens due to the temperature rise of the lead plug and the energy absorption capacity decreases accordingly. There is no problem.

  However, in the case of a subduction-type catastrophic earthquake, the seismic motion of the seismic isolation building is affected by the seismic motion that occurs in the epicenter region or the so-called long-period seismic motion that is caused by the influence of the deep ground structure even though it is relatively far away. It is predicted to be repeated for a long time with an amplitude larger than that previously considered. Since the amount of energy consumed by the lead plug is expected to exceed the conventionally assumed range when subjected to such a long-period ground motion, there is a concern that the energy absorption capacity may be reduced due to the temperature rise of the lead plug.

  Since the melting point of lead (327.5 ° C) is extremely lower than the melting point of steel (1530 ° C), which is often used as a damper, like lead, etc., vibrations with large amplitudes over a long period of time Temperature rise, which is not affected by steel, can be a problem with lead against seismic motion. For example, when the temperature of lead rises to near 100 ° C., lead is rapidly softened and the yield stress is lowered, so that there is a high possibility that the energy consumption capability, that is, the damping function is lowered. Further, if the temperature rises to near 200 ° C., there is a possibility that the rubber that is in contact with the lead plug is deteriorated and the horizontal deformation ability is lowered accordingly.

Here, the following two experimental results were conducted in order to confirm the change in the function of the lead plug under the situation where the laminated rubber bearing with the lead plug repeatedly undergoes a large horizontal deformation that can be experienced during a huge earthquake. Will be explained.
A) γ = ± 250% constant displacement amplitude 50 cycles for lead-containing laminated rubber bearings with a diameter of 250 mm B) Q = ± 66 kN constant load amplitude for 2 hours with 500 mm diameter lead-containing laminated rubber bearings Shake

  In the two experiments A) and B), the temperature of the lead plug can exceed the melting point of pure lead 327 ° C, assuming that the total energy consumption of the laminated rubber bearing with lead plug turns to the temperature rise of the lead plug. These are dynamic excitation experiments, both of which are sinusoidal excitation with a period of about 3 seconds. The temperature is measured by a thermocouple sensor.

The test specimen of A) can be considered as a test specimen of 1/4 scale of a laminated rubber bearing with a lead plug having a diameter of 1000 mm and a total rubber thickness of 200 mm as shown in Table 1 and FIG. The history curve of the experimental results is shown in FIG. 8- (a), and the change in the yield load characteristic value Qd and the transition of the lead upper and laminated rubber surface temperatures are shown in FIG. 8- (b). The upper portion of the lead means the upper portion of the entire length of the lead plug that is not subjected to shear deformation, and the surface of the laminated rubber means the inside of the covering rubber 22 in FIG. Figures 7 and 8 are quoted from Takao Nishizawa et al., The repeated vibration test experiment of laminated rubber with lead plugs, Summary of Annual Conference of Architectural Institute of Japan, August 2004.

  From Fig.8- (b), the temperature of the upper part of the lead rises every time the vibration cycle is repeated, and at the end of the vibration, the temperature rises from about 30 ° C to about 110 ° C by about 80 ° C. It can be seen that the related Qd has dropped to 0.7 times or less of the original. From this, it can be said that the behavior characteristic change of the lead-containing laminated rubber bearing subjected to the large-amplification many-time repeated deformation occurs due to the temperature rise of the lead portion and the accompanying decrease in the lead yield load.

  Experiment B) is an experiment conducted to clarify the behavior with respect to wind load. Here, excitation is performed for 2 hours and 2400 cycles continuously for the same load amplitude ± 66 kN as the design yield load characteristic value. . The test specimen shape and temperature measurement points are shown in FIG. 9, the temperature measurement results are shown in FIG. 10- (a), and the history curves of the experimental results are shown in FIG. 10- (b). 9 and 10 are quoted from the research on the soundness of LRB in the wind response of high-rise base-isolated buildings by Mr. Osamu Kawachi et al. (Part 2), Abstracts of Annual Conference of Architectural Institute of Japan, September 2003.

  Also in this experimental result, an increase in temperature is observed in each part of the laminated rubber, and there is a tendency for the lead yield load to decrease and the accompanying horizontal displacement amplitude to gradually increase. The temperature rise was most noticeable at the center of the lead plug, and the thermocouple sensor broke during vibration, making it impossible to measure. Since the temperature of the rubber part close to the lead plug has risen to near 90 ° C., it is considered that the consumed energy is converted into the thermal energy of the lead plug and the heat is transferred to the surroundings. The transmission of the thermal energy of the lead plug to the surrounding laminated rubber is considered to be the basis for the convergence of the yield load characteristic value decreasing in the experiment A) as the cycle is repeated.

  As described above, the temperature rise of the lead plug due to the deformation repeated many times leads to a decrease in the yield load and the energy absorption capacity of the lead plug. In order to maintain the function of the laminated rubber bearing, it is indispensable to suppress the temperature rise of the lead plug.

  It is envisioned that the temperature rise of the lead plug is suppressed to some extent by allowing the heat energy generated in the lead plug to be released from the surface of the lead plug. For this reason, it is considered that a certain purpose can be achieved by increasing the surface area of the lead plug. However, as described later, simply increasing the surface area does not always effectively suppress the temperature rise.

  As a method of increasing the surface area of the lead plug, there are a method of forming irregularities on the peripheral surface of the lead plug with ring-shaped steel plates stacked in multiple stages around the lead plug (see Patent Document 1), and a method of forming a metal plug that is not a lead plug. Although there is a method of forming irregularities on the surface (see Patent Document 2), there is no technology that takes measures to directly suppress the temperature rise of the lead plug.

Japanese Patent Laid-Open No. 10-159897 (Claim 1, paragraphs 0012 to 0018, FIGS. 4, 7, 9, and 11) JP-A-2005-273707 (Claim 1, paragraphs 0011, 0014, 0021, 0028, FIGS. 1 to 5)

  In Patent Document 1, irregularities are formed on the peripheral surface (surface) of the lead plug by steel plates stacked in multiple stages around the lead plug, but the peripheral surface occupying most of the surface of the lead plug is not a laminated rubber but a steel plate. (Intermediate steel plate) is in contact over the entire length. Here, because of the unevenness in the height direction of the contact portion between the lead plug and the steel plate, when the laminated rubber is deformed horizontally, lead with low rigidity is easily stirred vigorously at the contact portion. It is considered that the adhesion cannot be maintained and the temperature rise of the lead plug cannot be effectively suppressed.

  In Patent Document 2, since the structural steel material having a high melting point as described above is used instead of lead for the metal plug (paragraphs 0008 and 0021), the temperature rise of the metal plug does not become a problem. Therefore, Patent Document 2 does not have the problem of suppressing the temperature rise of the metal plug, nor the technical background (factor) leading to the problem.

  In Patent Document 2, although the concave portion is formed along the axial direction or along the circumferential direction on the peripheral surface of the metal plug, the metal plug is formed at the center of the laminated rubber and has a constant diameter. Since it is merely inserted into the cylindrical through hole (paragraphs 0020, 0034, FIG. 1, FIG. 5- (a)), there is always a gap between the laminated rubber and the position of the recess.

  Therefore, even if lead is used for the metal plug, and the temperature rise of the metal plug may be a problem, the thermal energy of the metal plug may not be transmitted directly to the surrounding laminated rubber. Since the amount is small, it is considered difficult to suppress the temperature rise of the metal plug. If there is a gap around the metal plug, the laminated rubber cannot obtain the effect of constraining the metal plug from the surroundings. Therefore, in the case of lead, it becomes difficult to use the metal plug as a damper.

  The present invention proposes a laminated rubber bearing with a plug that effectively suppresses the temperature rise of the plug.

  According to the first aspect of the present invention, a laminated rubber and a flange integrated with the upper and lower parts and joined to the upper structure and the lower structure, and a metal plug disposed at or near the central portion on the plane of the laminated rubber In a laminated rubber bearing with a plug, the plug is made of a low melting point metal, has a shape having a recess on the side of the laminated rubber around, and is in close contact with the laminated rubber on a peripheral surface. . The close contact mentioned here includes the case where an inclusion such as a rubber sheet of about 1 mm or less is sandwiched between the surface of the plug and the laminated rubber. The low melting point metal mainly refers to lead and tin.

  Since the plug has a shape having a recess on the side of the surrounding laminated rubber, the surface area of the plug is increased compared to the case where the plug is, for example, a columnar shape or a prismatic shape. It is possible to effectively transfer the heat energy to the laminated rubber. Since the concave portion is in a relative relationship with the convex portion, a portion other than the portion that becomes the convex portion is a relative concave portion with respect to the surface of the plug on the laminated rubber side. The shape of the recess is not questioned at all.

As shown in Table 2, the energy (heat capacity = specific heat × specific gravity) for raising 1 cm ³ of lead and tin by 1 ° C. is 1.43 J and 1.63 J, respectively. On the other hand, the energy for raising the rubber and steel by 1 ° C. is 1.65 J and 3.41 J, respectively. Therefore, the rubber and steel, which are the materials constituting the laminated rubber, are relatively in comparison with lead and tin. It can be said that the material does not easily rise in temperature.

  Moreover, since the diameter of the lead plug in the conventional laminated rubber bearing is about 20% of the diameter of the laminated rubber, the volume of the laminated rubber is about 25 times the volume of the lead plug. In this case, if heat energy is generated in the lead plug or tin plug to raise its temperature by 100 ° C., the heat transfer from the lead plug or tin plug to the laminated rubber is completely performed as shown in FIG. Assuming that the temperature difference between the lead plug and the laminated rubber disappears, it is estimated that the temperature rise of the entire laminated rubber bearing including the lead plug and the like stays below 4 ° C.

  The amount of heat energy transferred from the plug per unit time is determined by thermal conductivity × cross-sectional area (contact area) × temperature gradient (temperature difference). In addition, from the fact of the heat transfer from the lead plug or the like to the laminated rubber, by increasing the surface area of the plug as in the present invention, it is possible to efficiently cause the heat transfer from the plug to the laminated rubber, The temperature rise of the plug can be reliably suppressed.

  When the plug has a concave shape on the laminated rubber side, for example, if the plug has a cross-shaped cross section as described later, even if the plug generates heat, the contact area with the surrounding laminated rubber is large, resulting in a laminated rubber. Since the amount of heat transfer increases and the temperature rise of the plug can be suppressed, it is possible to suppress or prevent a decrease in energy absorption capability by the plug. When the flange is in contact with the top and bottom of the plug, the heat of the plug also moves to the flange due to the temperature difference between the plug and the flange.

  Due to the effect of heat transfer from the plug surface to the laminated rubber due to the increase in the surface area, the temperature of the plug surface tends to be lower than the temperature at the center of the plug than when there is no increase in the surface area. As a result, the heat transfer effect from the surface is promoted.

  If the plug is in contact with the flange at the upper end and the lower end as described in claim 2, as described above, the heat energy generated in the plug as shown in FIG. Since it is also transmitted to the flange, the effect of suppressing the temperature rise of the plug is improved, and the reduction of the energy absorption capability by the plug is further suppressed. Contact includes close contact.

  Since heat is transferred from the plug to the peripheral laminated rubber when the temperature rises in the plug, the invention according to claim 1 functionally applies the heat generated by the plug as described in claim 6. In other words, the invention according to claim 2 is a state in which the heat generated by the plug according to claim 6 is transmitted to the flange. In other words, it can be said. In claim 7, the heat generated in the plug is transmitted to the laminated rubber and the flange.

  The purpose of the present invention is to increase the surface area of the plug itself and to transfer heat from the plug to the surrounding laminated rubber, so that it has a concave portion on the laminated rubber side, and the surface area is larger than the original shape without the concave portion. As long as the shape increases, the shape of the plug is not limited. Specifically, the plug has a planar shape having a concave portion on the laminated rubber side as described in claim 3, or an elevational shape having a concave portion on the laminated rubber side as in claim 4, and the planar shape is a concave portion. For example, it has a concave polygonal shape such as a cross shape or a star shape. Since the plug has a concave portion on the surface, the plug has a concave and convex shape as a whole.

  Although the plug has a shape with a recess on the laminated rubber side, the peripheral surface of the plug is always restrained from the surroundings by the laminated rubber, so that the low rigidity of the plug can be reduced as in the case where the plug is used alone. Since there is no influence on the deformability and the like, there is no problem in the present invention even if there is a small thickness portion on the horizontal cross section. In order to prevent directionality in the mechanical characteristics, it is desirable to have a uniform shape in the circumferential direction, such as point symmetry or line symmetry.

  A plurality of plugs are arranged in a distributed manner in one central portion on the plane of the laminated rubber, or a plurality of plugs in the vicinity of the central portion of the laminated rubber as described in claim 5. In order to increase the surface area, it is advantageous to arrange a plurality of surfaces.

In a conventional laminated rubber bearing in which a cylindrical lead plug is enclosed, the diameter of the lead plug is about 20% of the diameter of the entire laminated rubber. However, in the present invention, the surface area of the plug is increased. Since the plug does not have a circular cross section continuous in the material axis direction (cylindrical shape), the plug may be disposed in a range exceeding 20% of the entire laminated rubber. When the diameter of the lead plug cylindrical is 20% of the diameter of the laminated rubber, the plane area of the lead plug than 0.1 ² /0.5 ^2, 4% of the total area of the laminated rubber.

  On the other hand, the limit horizontal deformation amount of the laminated rubber having a circular cross section is about 80% (0.8 D) of the diameter D. In this limit horizontal deformation, as shown in FIG. The part where the upper end circle and the lower end circle overlap each other bears the vertical load. Placing a plug without a vertical load bearing capacity in this region will cause an extreme decrease in the load bearing capacity of the laminated rubber. Therefore, in order to maintain the vertical load bearing capacity during the limit horizontal deformation of the laminated rubber, It is appropriate to place the plug in a region that is outside the region.

  The portion where the circular shape at the upper end and the circular shape at the lower end of the laminated rubber overlap is a band-like region having a width of 0.2D near the outer periphery of the laminated rubber, and the region other than that is a circle having a diameter of 0.6D. Become. Therefore, if the horizontal cross section of the plug does not protrude outside the circular region having a diameter of 0.6D, it is possible to maintain the vertical load bearing ability even during the limit horizontal deformation of the laminated rubber.

  In a laminated rubber bearing with a plug, the plug has a shape having a recess on the side of the surrounding laminated rubber, and the heat energy of the plug can be effectively transmitted to the laminated rubber by closely contacting the laminated rubber on the peripheral surface. In addition, the temperature rise of the plug can be suppressed, and the vibration energy absorbing effect by the plug can be exhibited even when the large deformation is subjected to repeated deformation many times.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 includes a laminated rubber 2 and a flange 3 that is integrated with the upper and lower structures and joined to the upper structure and the lower structure, and a metal plug 4 that is disposed at or near the center of the laminated rubber 2 on the plane. In the laminated rubber bearing with a plug, the plug 4 is made of a low-melting-point metal, has a shape having a concave portion on the side of the surrounding laminated rubber 2, and is concretely attached to the laminated rubber bearing 1 with the circumferential surface closely attached to the laminated rubber 2 An example is shown. The laminated rubber bearing 1 with a plug is joined to the upper structure and the lower structure directly or indirectly at the upper and lower flanges 3 having the bolt holes 3a.

  FIG. 1 shows a case where the cross-sectional shape of the plug 4 is a cross shape, and the plug 4 is formed in a shape that is continuous in the material axis direction with the same cross-section, but the planar shape or horizontal cross-sectional shape of the plug 4 is the same or similar. In addition to changing the cross-sectional area of the plug 4 in the material axis direction while forming the shape, the cross-sectional shape of the plug 4 may be changed in the material axis direction.

  The internal steel plate 21 constituting the laminated rubber 2 is formed with holes or openings having a shape corresponding to the shape of the plug 4, particularly a planar shape, and the upper and lower ends of the plug 4 are the lower surface and the lower portion of the upper flange 3, respectively. The upper surface of the flange 3 is contacted or closely adhered. When the cross-sectional shape of the plug 4 changes in the material axis direction, holes or openings corresponding to the cross-sectional shape of each level are formed in the internal steel plate 21.

  Since the cross-sectional area (horizontal cross-sectional area) of the plug 4 is determined by the design of the base-isolated building, that is, depending on the magnitude of the damping force to be expected for the plug 4 of the laminated rubber bearing 1 per unit, In determining the specific shape (planar shape or elevational shape) of the plug 4 for suppressing the temperature rise, how much the surface area (peripheral length) can be increased while maintaining a constant cross-sectional area. Is a guide.

  FIGS. 2A to 2J show specific planar shape examples of the plug 4. When (a) is formed into a shape having blades in three circumferential directions on the plane, (b) is formed into a shape (cross shape) having blades in all directions, (c) is (a) (D) is a case where it is formed in an H shape, and (e) is a case where a part of a circle is formed in an arc shape from the outside. When (f) is formed in a star shape, (g) is formed in a shape with a circle on the tip of a cruciform blade (array shape), and (h) is when the circumferential surface of the circle is formed in a waveform. , (I) is a case where the H shape is formed to be orthogonal to each other, and (j) is a case where a part of the circle is cut into an elliptical arc shape from the outside.

  FIG. 3 is a cross-sectional view of the blade by making the planar shape of the corner of the blade curved so as to avoid stress concentration at the corner where the cross-section changes suddenly when the plug 4 has a cross shape. The case where the sudden change point is a curved surface is shown. Making the corners of the blades curved is applied to the shape excluding (h) in FIG.

  A plurality of plugs 4 shown in FIGS. 2 and 3 may be distributed in the vicinity of the central portion of the laminated rubber 2. The plurality of plugs 4 are arranged in parallel in the diameter direction of the laminated rubber 2 having a circular cross section, in parallel with the diagonal direction of the laminated rubber 2 having a polygonal cross section, or evenly arranged in the circumferential direction.

  FIG. 4 is a comparison of the circumference of the planar plug 4 shown in FIGS. 2A to 2C having the same plane area as the lead plug having a circular section (cylindrical shape) with the circumference of the plug having a circular section. The state of is shown. FIG. 4A shows a state in which a lead plug having a circular cross section having a diameter of 0.2D is arranged at the center of a laminated rubber having a circular cross section having a diameter D.

  Here, the plug 4 has the same cross-sectional area as the lead plug shown in FIG. 4- (a) and has a size inscribed in a circle having a diameter of 0.4D, for example, as shown in FIGS. 4- (b) to (d). Is determined, the circumferential length of each plug 4 shown in (b) to (d) is 2.02, 2.55, and 3.62 times, respectively. A circle having a diameter of 0.4D is a circle having a radius smaller by 0.1D than a circle excluding a belt-like region having a width of 0.2D near the outer periphery of the laminated rubber in FIG. As the circumference ratio increases, the contact area with the laminated rubber 2 increases, so that the heat energy generated by the plug 4 is efficiently transmitted to the laminated rubber 2.

  The contact area of the plug 4 shown in FIGS. 4- (b) to (d) with the steel flanges 3 above and below the laminated rubber bearing 1 is the same as in the case of the circle shown in FIG. )), The temperature gradient in the plug 4 (temperature difference between the central portion and the surface portion of the plug 4) described in the paragraph 0026 is considered to increase, so that the amount of heat transfer is expected to increase. Will be. As a result, in the case of FIGS. 4B to 4D, the temperature rise of the plug 4 is suppressed compared to the case of FIG. 4A, and the vibration energy is absorbed by the plug 4 when it is repeatedly deformed many times with a large amplitude. The effect will be exhibited effectively.

It is the partial cross section perspective view which showed the manufacture example of the laminated rubber bearing with a plug of this invention. (A)-(j) is the top view which showed the example of the concrete planar shape of a plug. It is the top view which showed the case where the corner part of the plug of the shape shown to FIG. 2- (b) was formed in curve shape. (A) is the top view which showed the arrangement | positioning state in the laminated rubber of the conventional lead plug, (b)-(d) is the top view which showed the arrangement | positioning state of the plug of this invention. It is the longitudinal cross-sectional view which showed the mode of the heat transfer from a plug to laminated rubber. (A) is the top view which showed the relationship between the diameter of a laminated rubber, and a deformation | transformation amount when the laminated rubber of a circular cross section reached a limit horizontal deformation, (b) is a longitudinal cross-sectional view of (a). It is the longitudinal cross-sectional view which showed the test body of the laminated rubber bearing containing lead when conducting the vibration experiment which produces a fixed displacement. (A) is the graph which showed the hysteresis curve of lead by the vibration experiment which produces a fixed displacement, (b) is the graph which showed temperature rise of lead, and deterioration of yield stress. It is the longitudinal cross-sectional view which showed the test body of the laminated rubber bearing containing lead when conducting the vibration experiment which applies a fixed load. (A) is the graph which showed the temperature rise of lead by the vibration experiment which applies a fixed load, (b) is the graph which showed the hysteresis curve of lead.

Explanation of symbols

1 ... Laminated rubber support 2 ... Laminated rubber 21 ... Internal steel plate 22 ... Coated rubber 3 ... Flange 3a ... Bolt hole 4 ... Plug

Claims (7)

  In a laminated rubber bearing with a plug, which is composed of a laminated rubber and a flange that is integrated with the upper and lower structures and joined to the upper structure and the lower structure, and a central portion on the plane of the laminated rubber, or a metal plug disposed in the vicinity thereof, A plug-containing laminated rubber bearing, wherein the plug is made of a low-melting-point metal, has a shape having a recess on the laminated rubber side around the plug, and is in close contact with the laminated rubber on a peripheral surface.   The plug-containing laminated rubber bearing according to claim 1, wherein the plug is in contact with the flange at an upper end and a lower end.   3. The laminated rubber bearing with a plug according to claim 1, wherein the plug has a planar shape having a recess on the laminated rubber side. The plug-containing laminated rubber bearing according to any one of claims 1 to 3, wherein the plug has an upright shape having a recess on the laminated rubber side.   The plug-containing laminated rubber bearing according to any one of claims 1 to 4, wherein a plurality of plugs are distributed in the vicinity of the center portion of the laminated rubber.   In a laminated rubber bearing with a plug, which is composed of a laminated rubber and a flange that is integrated with the upper and lower structures and joined to the upper structure and the lower structure, and a central portion on the plane of the laminated rubber, or a metal plug disposed in the vicinity thereof, A plug-containing laminated rubber bearing, wherein the plug is made of a low melting point metal, and heat generated by the plug is transmitted to the laminated rubber. The laminated rubber bearing with a plug according to claim 6, wherein heat generated by the plug is transmitted to the flange.