Base isolation device

Abstract

To provide a base isolation device capable of changing damping according to response displacement.SOLUTION: A top face of a lower shoe 2 is provided with a lower sliding surface 241 and 242 which is formed in a V-shape recessed downward gradually upward from the center in the X-direction (first horizontal direction) toward both ends and on which a slider 4 slides. A lower surface of an upper shoe 3 is provided with an upper sliding surface which is formed in an inverted V-shape recessed upward gradually downward from the center in the Y-direction (second horizontal direction) toward both ends and on which the slider slides. The dimensions of the lower sliding surface 241 and 242 in the Y direction are not constant over the entire X-direction and are set to be different depending on the position in the X-direction, and the dimensions of the upper sliding surface in the X-direction are not constant over the entire Y-direction and are set to be different depending on the position in the Y-direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a seismic isolation device. [Background technology]

[0002] In seismic isolation structures, laminated rubber bearings and sliding bearings are commonly used as seismic isolation bearings that support the structure's own weight. Laminated rubber bearings are highly efficient but tend to be expensive, and are difficult to accommodate large displacements. In contrast to laminated rubber bearings, sliding bearings have the problem that the displacement does not return to the origin after the device is activated. In response to this, the inventor and others have already invented an inclined sliding bearing, in which the sliding surface of the sliding bearing is inclined (see, for example, Patent Documents 1 and 2). In an inclined sliding bearing, friction plates are provided on both the upper and lower shoe parts of the bearing to achieve a certain effect. This generates frictional force during earthquake response, enhancing the seismic isolation effect. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-130216 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-230033 [Patent Document 3] Patent Application No. 2021-025300 Summary of the Invention [Problem to be solved by the invention]

[0004] Spherical sliding bearings have the problem that the restoring force is small near the original position because there is almost no gradient on the spherical surface, and a certain amount of residual displacement occurs. Also, due to the curvature of the spherical surface, the friction force increases as the bearing moves away from the original position, i.e., as the seismic isolation displacement increases. However, since there is no upper limit on the friction force, the friction force increases without limit, which leads to a deterioration in seismic isolation performance and makes the bearing unsuitable for cases where large displacements occur, such as long-period or massive earthquakes.

[0005] The friction coefficient μ of conventional inclined sliding bearings has been constant with respect to displacement δ (μ = μd). In contrast, by changing the friction coefficient μ with respect to the displacement of the bearing, it is possible to further improve the seismic isolation effect (displacement-dependent seismic isolation). Regarding displacement-dependent seismic isolation, as shown in Patent Document 3, for example, displacement-dependent dampers have existed in the past, but displacement-dependent bearings have not.

[0006] Therefore, an object of the present invention is to provide a seismic isolation device that can change damping in accordance with response displacement. [Means for solving the problem]

[0007] In order to achieve the above object, the seismic isolation device according to the present invention is provided between a lower structure and an upper structure which are relatively displaceable in a horizontal direction, and includes a lower shoe fixed on the lower structure, an upper shoe fixed below the upper structure, and a slider disposed between the lower shoe and the upper shoe, which is relatively displaceable with the lower shoe in a first horizontal direction and is relatively displaceable with the upper shoe in a second horizontal direction perpendicular to the first horizontal direction, and the upper surface of the lower shoe is formed in a V-shape which is concave downward and gradually extends upward from the center toward both ends in the first horizontal direction, A lower sliding surface on which the slider slides is provided, and an upper sliding surface on which the slider slides is provided, the lower surface of the upper shoe being formed in an inverted V-shape that is concave upward and gradually extends downward from the center toward both ends in the second horizontal direction, and the dimension of the lower sliding surface in the second horizontal direction is not constant throughout the first horizontal direction, but is set to vary depending on the position in the first horizontal direction, and the dimension of the upper sliding surface in the first horizontal direction is not constant throughout the second horizontal direction, but is set to vary depending on the position in the second horizontal direction.

[0008] In the present invention, the second horizontal dimension of the lower slide surface is set to vary depending on the position in the first horizontal direction, and the first horizontal dimension of the upper slide surface is set to vary depending on the position in the second horizontal direction. As a result, the friction between the slider and the lower slide surface of the lower shoe and the friction between the slider and the upper slide surface of the upper shoe vary depending on the position of the slider relative to the lower shoe and the upper shoe. Therefore, by changing the second horizontal dimension of the lower slide surface at a predetermined position in the first horizontal direction and changing the first horizontal dimension of the upper slide surface at a predetermined position in the second horizontal direction, it is possible to change the damping in accordance with the response displacement. Note that the change in the dimension (width) of the lower slide surface does not necessarily have to match the change in the dimension (width) of the upper slide surface. This eliminates the need to install a damper device such as a displacement-dependent friction damper or oil damper separately from the seismic isolation device of the present invention, thereby reducing the effort and costs involved in installation and maintenance.

[0009] In the seismic isolation device according to the present invention, the dimension of the lower sliding surface in the second horizontal direction gradually increases from the center in the first horizontal direction toward both ends to a predetermined position, and is set constant from the predetermined position toward both ends in the first horizontal direction; the dimension of the upper sliding surface in the first horizontal direction gradually increases from the center in the second horizontal direction toward both ends to a predetermined position, and is set constant from the predetermined position toward both ends in the second horizontal direction; and in an initial state, the slider is disposed above the center in the first horizontal direction of the lower sliding surface and is set constant from the predetermined position toward both ends in the second horizontal direction. The coefficient of friction between the slider, which is positioned below the center of the upper slide surface in the second horizontal direction and positioned above both ends of the lower slide surface from the specified position in the first horizontal direction, and the lower slide surface, may be greater than the coefficient of friction between the slider, which is positioned above the center of the lower slide surface in the first horizontal direction, and the lower slide surface; and the coefficient of friction between the slider, which is positioned below both ends of the upper slide surface from the specified position in the second horizontal direction, and the upper slide surface, may be greater than the coefficient of friction between the slider, which is positioned below the center of the upper slide surface in the second horizontal direction, and the upper slide surface.

[0010] With this configuration, the coefficient of friction between the slider and the lower slide surface and the coefficient of friction between the slider and the upper slide surface in the initial state (original position) are smaller than the coefficients of friction between the slider and the lower slide surface and the upper slide surface when the slider is displaced beyond a predetermined position relative to the lower slide surface and the upper slide surface, and therefore the response acceleration can be reduced at an early stage when the lower structure and the upper structure are displaced relative to each other.

[0011] Furthermore, in the seismic isolation device of the present invention, the coefficient of friction between the slider and the lower slide surface may be set to increase linearly in proportion to the displacement from the center in the first horizontal direction as the slider moves from the center in the first horizontal direction of the lower slide surface toward the predetermined position, and the coefficient of friction between the slider and the upper slide surface may be set to increase linearly in proportion to the displacement from the center in the second horizontal direction as the slider moves from the center in the second horizontal direction of the upper slide surface toward the predetermined position.

[0012] By adopting such a configuration, the response acceleration can be reduced.

[0013] Furthermore, in the seismic isolation device according to the present invention, the dimension of the lower sliding surface in the second horizontal direction is constant from the center toward both ends in the first horizontal direction to a predetermined position, and is set to gradually decrease from the predetermined position toward both ends in the first horizontal direction, and the dimension of the upper sliding surface in the first horizontal direction is constant from the center toward both ends in the second horizontal direction to a predetermined position, and is set to gradually decrease from the predetermined position toward both ends in the second horizontal direction, and in an initial state, the slider is disposed above the center of the lower sliding surface in the first horizontal direction and below the center of the upper sliding surface in the second horizontal direction, and the coefficient of friction between the slider disposed above both ends of the lower sliding surface from the predetermined position in the first horizontal direction and the lower sliding surface is The coefficient of friction between the slider disposed above the lower slide surface between the center in the first horizontal direction and the predetermined position and the lower slide surface may be smaller than the coefficient of friction between the slider disposed above the lower slide surface between the center in the first horizontal direction and the predetermined position, and the coefficient of friction between the slider disposed below the predetermined position on the upper slide surface between the center in the second horizontal direction and the predetermined position and the upper slide surface may be smaller than the coefficient of friction between the slider disposed below ..., and the coefficient of friction between the slider disposed above the lower slide surface between the center in the second horizontal direction and the predetermined position and the upper slide surface may be smaller than the coefficient of friction between the slider disposed below the upper slide surface between the center in the second horizontal direction and the predetermined position, and the coefficient of friction between the slider disposed above the upper slide surface between the predetermined position on the upper slide surface and the predetermined position, and the coefficient of friction between the slider disposed above the upper slide surface between the center in the second horizontal direction and the predetermined position and the upper slide surface may be smaller than the coefficient of friction between the slider disposed above the upper slide surface between the center in the second horizontal direction and the predetermined position, and the coefficient of friction between the slider disposed above the upper slide surface between the predetermined position on the upper slide surface and the predetermined position, and the coefficient of friction

[0014] By configuring the seismic isolation device in this way, the sliders do not slide against the lower shoe and upper shoe when subjected to relatively small wind loads or earthquake loads, and the seismic isolation function does not work, but the seismic isolation function works when subjected to large earthquakes. [Effects of the Invention]

[0015] According to the present invention, damping can be changed in accordance with the response displacement. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is an exploded perspective view of the seismic isolation device according to the first embodiment. [Figure 2] FIG. 1 is a plan view of a seismic isolation device according to a first embodiment. [Figure 3] FIG. 2 is a side view of the seismic isolation device according to the first embodiment as viewed from the Y direction. [Figure 4] FIG. 2 is a side view of the seismic isolation device according to the first embodiment as viewed from the X direction. [Figure 5] FIG. [Figure 6] FIG. 1 is a perspective view of a seismic isolation device according to a first embodiment. [Figure 7] Graph (a) shows the relationship between surface pressure and coefficient of friction, and graph (b) shows the relationship between the ratio of contact area and coefficient of friction. [Figure 8] 1 is a diagram and graph showing changes in the coefficient of friction; [Figure 9] FIG. 10 is a schematic diagram showing a restoring force. [Figure 10] 10 is a diagram showing the arrangement of sliding members in a seismic isolation device according to a second embodiment, and a graph showing the relationship between displacement and friction coefficient. [Figure 11] FIG. 1 is a schematic diagram of an analytical model. [Figure 12] 10 is a graph showing the friction restoring force characteristics and tilt restoring force characteristics of a tilt sliding bearing. [Figure 13] 10 is a graph showing the friction restoring force characteristics and tilt restoring force characteristics of a displacement-dependent tilt sliding bearing. [Figure 14] This is a table of seismic waves. [Figure 15] 10 is a graph showing the response acceleration when the seismic wave is the 1940 El Centro wave (NS component). [Figure 16] 10 is a graph showing the response acceleration when the seismic wave is the 1952 Taft wave (EW component). [Figure 17] This is a graph showing the response acceleration when the earthquake wave is from Hachinohe in 1968 (NS component). [Figure 18] This is a graph showing the response acceleration when the seismic wave is the notified wave (Kobe phase). [Figure 19]10 is a graph showing the response acceleration when the earthquake wave is a public notice wave (Kanto phase). [Figure 20] This is a graph showing the response acceleration when the seismic wave is the announcement wave (Hachinohe phase). [Figure 21] This is a graph showing the response displacement when the seismic wave is the 1940 El Centro wave (NS component). [Figure 22] 10 is a graph showing the response displacement when the seismic wave is the 1952 Taft wave (EW component). [Figure 23] This is a graph showing the response displacement when the earthquake wave is from Hachinohe in 1968 (NS component). [Figure 24] This is a graph showing the response displacement when the seismic wave is the notified wave (Kobe phase). [Figure 25] This is a graph showing the response displacement when the seismic wave is a public notice wave (Kanto phase). [Figure 26] This is a graph showing the response displacement when the seismic wave is the announcement wave (Hachinohe phase). [Figure 27] This is a graph showing the residual displacement when the seismic wave is the 1940 El Centro wave (NS component). [Figure 28] This is a graph showing the residual displacement when the seismic wave is the 1952 Taft wave (EW component). [Figure 29] This is a graph showing the residual displacement when the seismic wave is from Hachinohe in 1968 (NS component). [Figure 30] This is a graph showing the residual displacement when the seismic wave is the notified wave (Kobe phase). [Figure 31] This is a graph showing the residual displacement when the seismic wave is a public notice wave (Kanto phase). [Figure 32] This is a graph showing the residual displacement when the seismic wave is the announcement wave (Hachinohe phase). DETAILED DESCRIPTION OF THE INVENTION

[0017] (First embodiment) A seismic isolation device according to an embodiment of the present invention will be described below with reference to FIGS. A plurality of seismic isolation devices 1 according to this embodiment shown in Figures 1 to 4 are provided in a seismic isolation layer 13 between a lower structure 11 (see Figures 3 and 4) and an upper structure 12 (see Figures 3 and 4). Each of the plurality of seismic isolation devices 1 provided in the seismic isolation layer 13 has the same configuration. The seismic isolation device 1 has a lower shoe 2 fixed to the upper surface of the lower structure 11, an upper shoe 3 fixed to the lower surface of the upper structure 12, and a slider 4 arranged between the lower shoe 2 and the upper shoe 3.

[0018] The lower shoe 2 has a main body 22 having a lower shoe sliding portion 21 on which the slider 4 slides, and a fixed portion 23 connected to the lower part of the main body 22 and fixed to the lower structure 11. The main body 22 is formed in a long block shape and is disposed so as to extend in a first horizontal direction. Hereinafter, the first horizontal direction will be referred to as the X direction, and the second horizontal direction perpendicular to the first horizontal direction will be referred to as the Y direction. The upper surface of the main body 22 is formed along the X direction as a generally V-shaped inclined surface that is convex downward at approximately the center in the X direction. This upper surface of the main body 22 is the lower shoe sliding part 21.

[0019] The bent portion approximately in the center of the lower shoe sliding portion 21 is referred to as bent portion 21a. Of the lower shoe sliding portion 21, one side in the X direction from bent portion 21a is referred to as first lower shoe sliding portion 211, and the other side in the X direction from bent portion 21a is referred to as second lower shoe sliding portion 212. The end portion on one side in the X direction of the lower shoe sliding portion 21, i.e., the end portion on one side in the X direction of the first lower shoe sliding portion 211, is referred to as first end portion 21b, and the end portion on the other side in the X direction of the lower shoe sliding portion 21, i.e., the end portion on the other side in the X direction of the second lower shoe sliding portion 212, is referred to as second end portion 21c. The first lower shoe sliding portion 211 and the second lower shoe sliding portion 212 are each formed on an inclined surface that is a flat surface. The inclination angles of the first lower shoe sliding part 211 and the second lower shoe sliding part 212 relative to the horizontal plane are set to the same value (inclination angle θ). The shapes of the surfaces of the first lower shoe sliding part 211 and the second lower shoe sliding part 212 are each elongated rectangles that are long along the inclination direction.

[0020] The first lower shoe sliding portion 211 and the second lower shoe sliding portion 212 are each provided with a lower shoe sliding plate 24 that reduces friction with the slider 4. The lower shoe sliding plate 24 is flat. The lower shoe sliding plate 24 is, for example, a stainless steel plate. The lower shoe sliding plate 24 may be a plated steel plate or Teflon (registered trademark). The upper surface of the lower shoe sliding plate 24 provided on the first lower shoe sliding portion 211 is referred to as a first lower sliding surface 241, and the upper surface of the lower shoe sliding plate 24 provided on the second lower shoe sliding portion 212 is referred to as a second lower sliding surface 242. The first lower sliding surface 241 is a surface that follows the slope of the first lower shoe sliding portion 211. The second lower sliding surface 242 is a surface that follows the slope of the second lower shoe sliding portion 212. The first lower sliding surface 241 and the second lower sliding surface 242 may be collectively referred to as the lower sliding surfaces 241, 242.

[0021] The first lower slide surface 241 is provided over the entire X-direction of the first lower shoe sliding part 211. A predetermined range of the first lower slide surface 241 on the other side in the X-direction, i.e., on the side of the bent part 21a of the lower shoe sliding part 21, is formed so that the dimension in the Y-direction gradually increases from the other side in the X-direction to one side. The portion of the first lower slide surface 241 on one side in the X-direction is formed so that the dimension in the Y-direction extends over the entire Y-direction of the first lower shoe sliding part 211. The first lower slide surface 241 has a shape symmetrical with respect to the Y-direction. The second lower slide surface 242 has a shape symmetrical with respect to the first lower slide surface 241 in the X-direction. The portions of the first lower slide surface 241 and the second lower slide surface 242 where the dimension in the Y-direction gradually increases from the other side in the X-direction to one side or from one side to the other are referred to as contact area change ranges 24a. The portions of the first lower slide surface 241 and the second lower slide surface 242 where the dimension in the Y direction is constant are referred to as constant contact area portions 24b. Hereinafter, the distance in the X direction of the contact area change range 24a may be referred to as d.

[0022] End faces 221, 221 on both sides of the main body 22 in the Y direction are each substantially vertical faces facing the Y direction. The fixing portion 23 is formed in a plate shape and is joined to the lower surface of the main body portion 22 with the plate surface oriented in a horizontal plane. The fixing portion 23 is formed in a substantially rectangular shape that is larger in the X and Y directions than the main body portion 22, and protrudes in the X and Y directions beyond the main body portion 22. The fixing portion 23 is fixed to the upper surface of the lower structure 11.

[0023] As shown in Figures 3, 4 and 6, the upper shoe 3 has a main body 32 having an upper shoe sliding portion 31 on which the slider 4 slides, and a fixed portion 33 connected to the top of the main body 32 and fixed to the upper structure 12. The main body 32 is formed in a long block shape and is disposed so as to extend in the Y direction. The lower surface of the main body 32 is formed in a generally inverted V-shaped inclined surface along the Y direction, with the approximate center in the Y direction being convex upward. The lower surface of this main body 32 is the upper shoe sliding part 31.

[0024] The bent portion approximately in the center of the upper shoe sliding portion 31 is referred to as bent portion 31a. Of the upper shoe sliding portion 31, one side in the Y direction from bent portion 31a is referred to as first upper shoe sliding portion 311, and the other side in the Y direction from bent portion 31a is referred to as second upper shoe sliding portion 312. The end portion on one side in the Y direction of the upper shoe sliding portion 31, i.e., the end portion on one side in the Y direction of the first upper shoe sliding portion 311, is referred to as first end portion 31b, and the end portion on the other side in the Y direction of the lower shoe sliding portion 21, i.e., the end portion on the other side in the Y direction of the second lower shoe sliding portion 212, is referred to as second end portion 31c. The first upper shoe sliding portion 311 and the second upper shoe sliding portion 312 are each formed on an inclined surface that is a flat surface. The inclination angles of the first upper shoe sliding portion 311 and the second upper shoe sliding portion 312 relative to the horizontal plane are set to the same value (inclination angle θ). The inclination angle θ of the first upper shoe sliding portion 311 and the second upper shoe sliding portion 312 relative to the horizontal plane is the same as the inclination angle θ of the first lower shoe sliding portion 211 and the second lower shoe sliding portion 212 relative to the horizontal plane. The shapes of the surfaces of the first upper shoe sliding portion 311 and the second upper shoe sliding portion 312 are each elongated rectangles that are long along the inclination direction.

[0025] The first upper shoe sliding portion 311 and the second upper shoe sliding portion 312 are each provided with an upper shoe sliding plate 34 that reduces friction with the slider 4. The upper shoe sliding plate 34 is flat. The upper shoe sliding plate 34 is, for example, a stainless steel plate. The upper shoe sliding plate 34 may be a plated steel plate or Teflon (registered trademark). The lower surface of the upper shoe sliding plate 34 provided on the first upper shoe sliding portion 311 is referred to as a first upper sliding surface 341, and the lower surface of the upper shoe sliding plate 34 provided on the second upper shoe sliding portion 312 is referred to as a second upper sliding surface 342. The first upper sliding surface 341 is a surface that follows the slope of the first upper shoe sliding portion 311. The second upper sliding surface 342 is a surface that follows the slope of the second upper shoe sliding portion 312. The first upper sliding surface 341 and the second upper sliding surface 342 may be collectively referred to as the upper sliding surfaces 341, 342.

[0026] The first upper slide surface 341 is provided over the entire Y direction of the first upper shoe sliding part 311. The other side of the first lower slide surface 241 in the Y direction, i.e., the portion on the side of the bent part 31a of the upper shoe sliding part 31, is formed so that the dimension in the X direction gradually increases from the other side in the Y direction to one side. The portion of the first upper slide surface 341 on one side in the Y direction is formed so that the dimension in the X direction extends over the entire X direction of the first upper shoe sliding part 311. The first lower slide surface 241 has a shape symmetrical with respect to the X direction. The second upper slide surface 342 has a shape symmetrical with respect to the first upper slide surface 341 in the Y direction. The portions of the first upper slide surface 341 and the second upper slide surface 342 where the dimension in the X direction gradually increases from the other side to one side in the Y direction or from one side to the other are referred to as contact area change ranges 34a. The portions of the first upper sliding surface 341 and the second upper sliding surface 342 where the dimension in the X direction is constant are referred to as constant contact area portions 34b. Hereinafter, the distance in the Y direction of the contact area change range 34a may be referred to as d.

[0027] End faces 321, 321 on both sides of the main body 32 in the X direction are formed so as to be substantially vertical faces facing the X direction. The fixing portion 33 is formed in a plate shape and is joined to the upper surface of the main body portion 32 with the plate surface oriented in a horizontal plane. The fixing portion 33 is formed in a substantially rectangular shape that is larger in the X and Y directions than the main body portion 32, and protrudes in the X and Y directions beyond the main body portion 32. The fixing portion 33 is fixed to the lower surface of the upper structure 12.

[0028] The lower shoe 2 and the upper shoe 3 are arranged so as to overlap with a gap in the vertical direction, and a slider 4 is arranged at an intersection 10 (see FIG. 2) where the lower shoe 2 and the upper shoe 3 overlap with each other in the vertical direction.

[0029] As shown in FIGS. 1 and 5 , the slider 4 has a sliding portion 41, a pair of lower guide portions 46, 46, and a pair of upper guide portions 47, 47. A lower sliding surface 42 that comes into contact with the lower shoe sliding portion 21 is formed at the lower portion of the sliding portion 41. The lower sliding surface 42 faces downward. An upper sliding surface 43 that comes into contact with the upper shoe sliding portion 31 is formed at the upper portion of the slider 4. The upper sliding surface 43 faces upward. The pair of lower guide portions 46, 46 protrude downward from both edges of the sliding portion 41 in the Y direction and are disposed on both sides of the main body portion 22 of the lower shoe 2 in the Y direction. The pair of upper guide portions 47, 47 protrude upward from both edges of the sliding portion 41 in the X direction and are disposed on both sides of the main body portion 32 of the upper shoe 3 in the X direction. The sliding portion 41 is block-shaped and has a substantially square shape in plan view (shape as seen from above).

[0030] As shown in FIG. 5 , the lower sliding surface 42 is disposed between a pair of lower guide portions 46, 46. The lower sliding surface 42 is formed along the X direction as a generally V-shaped inclined surface with a generally central portion in the X direction convex downward. The bent portion of the lower sliding surface 42 approximately in the central portion in the X direction is referred to as a bent portion 421. Of the lower sliding surface 42, one side in the X direction of the bent portion 421 is referred to as a first lower sliding surface 422, and the other side in the X direction of the bent portion 421 is referred to as a second lower sliding surface 423. The inclination angles of the first lower sliding surface 422 and the second lower sliding surface 423 with respect to the horizontal plane are set to the same value (inclination angle θ). The inclination angle θ of the first lower sliding surface 422 and the second lower sliding surface 423 with respect to the horizontal plane is the same as the inclination angle θ of the first lower shoe sliding portion 211 and the second lower shoe sliding portion 212 with respect to the horizontal plane. The first lower sliding surface 422 and the second lower sliding surface 423 are each provided with a lower friction material 424. The lower friction material 424 is, for example, a resin material such as Teflon (registered trademark).

[0031] As shown in FIG. 1 , the upper sliding surface 43 is disposed between a pair of upper guide portions 47, 47. The upper sliding surface 43 is formed along the Y direction as a generally inverted V-shaped inclined surface with a generally central portion in the Y direction convex upward. The bent portion of the upper sliding surface 43 at the generally central portion in the Y direction is referred to as a bent portion 431. Of the upper sliding surface 43, one side in the X direction of the bent portion 431 is referred to as a first upper sliding surface 432, and the other side in the Y direction of the bent portion 431 is referred to as a second upper sliding surface 433. The inclination angles of the first upper sliding surface 432 and the second upper sliding surface 433 with respect to the horizontal plane are set to the same value (inclination angle θ). The inclination angle θ of the first upper sliding surface 432 and the second upper sliding surface 433 with respect to the horizontal plane is the same as the inclination angle θ of the first upper shoe sliding portion 311 and the second upper shoe sliding portion 312 with respect to the horizontal plane. An upper friction material 434 is provided on each of the first upper sliding surface 432 and the second upper sliding surface 433. The upper friction material 434 is a resin material such as Teflon (registered trademark).

[0032] 4, when the slider 4 is disposed above the lower shoe 2, the lower friction material 424 of the lower sliding surface 42 comes into contact with the lower sliding surfaces 241, 242 of the lower shoe sliding portion 21 of the lower shoe 2, and the pair of lower guide portions 46, 46 are disposed on both sides in the Y direction of the main body portion 22 of the lower shoe 2. The inner surfaces of the pair of lower guide portions 46, 46 face the end faces 221, 221 on both sides in the Y direction of the main body portion 22. In this embodiment, sliding members 461, 461 are provided on the inner surfaces of the pair of lower guide portions 46, 46, and the sliding members 461, 461 come into contact with the end faces 221, 221 of the main body portion 22. 3, when the slider 4 is disposed below the upper shoe 3, the upper friction material 434 of the upper sliding surface 43 comes into contact with the upper sliding surfaces 341, 342 of the upper shoe sliding portion 31 of the upper shoe 3, and the pair of upper guide portions 47, 47 are disposed on both sides in the X direction of the main body portion 32 of the upper shoe 3. The inner surfaces of the pair of upper guide portions 47, 47 face the end faces 321, 321 on both sides in the X direction of the main body portion 32. In this embodiment, sliding members 471, 471 are provided on the inner surfaces of the pair of upper guide portions 47, 47, and the sliding members 471, 471 come into contact with the end faces 321, 321 of the main body portion 32.

[0033] When an earthquake occurs and the lower structure 11 and the upper structure 12 are displaced relative to each other in the horizontal direction, the seismic isolation device 1 causes the slider 4 to slide on the lower shoe sliding portion 21 and the upper shoe sliding portion 31 in response to the relative displacement between the lower shoe 2 provided on the lower structure 11 and the upper shoe 3 provided on the upper structure 12.

[0034] As described above, when the slider 4 slides on the lower shoe sliding part 21, the lower friction material 424 of the slider 4 comes into contact with the lower sliding surfaces 241, 242 of the lower shoe sliding part 21. When the slider 4 slides in the contact area changing range 24a on the lower sliding surfaces 241, 242, the area of ​​contact of the lower friction material 424 with the lower sliding surfaces 241, 242 of the lower shoe sliding part 21 changes depending on the amount of displacement. When the slider 4 slides on the contact area constant portion 24b on the lower sliding surfaces 241, 242, the area of ​​contact of the lower friction material 424 with the lower sliding surfaces 241, 242 of the lower shoe sliding part 21 is constant regardless of the amount of displacement.

[0035] As described above, when the slider 4 slides on the upper shoe sliding portion 31, the upper friction material 434 of the slider 4 comes into contact with the upper sliding surfaces 341, 342 of the upper shoe sliding portion 31. When the slider 4 slides in the contact area changing range 34a on the upper sliding surfaces 341, 342, the area of ​​contact between the upper friction material 434 and the upper sliding surfaces 341, 342 of the upper shoe sliding portion 31 changes depending on the amount of displacement. When the slider 4 slides in the contact area constant portion 34b on the upper sliding surfaces 341, 342, the area of ​​contact between the upper friction material 434 and the upper sliding surfaces 341, 342 of the upper shoe sliding portion 31 is constant regardless of the amount of displacement.

[0036] FIG. 7(a) shows the relationship between the contact pressure and the friction coefficient μ when the resin material (lower friction material 424, upper friction material 434) and the stainless steel (lower slide surfaces 241, 242, upper slide surfaces 341, 342) come into contact. μ is the friction coefficient that changes with changes in contact pressure. If the amount of applied load is P and the area of ​​the lower slide surfaces 241, 242 and the upper slide surfaces 341, 342 where the lower friction material 424 and the upper friction material 434 come into contact is A, the contact pressure is expressed as P / A. As shown in FIG. 7(a), the greater the contact pressure, the smaller the friction coefficient μ. Figure 7(b) shows the relationship between the contact area of ​​the lower friction material 424 and the upper friction material 434 and the lower slide surfaces 241, 242 and the upper slide surfaces 341, 342 and the friction coefficient μ. The area change rate on the horizontal axis is calculated assuming that the design surface pressure is 15 MPa, and shows that the friction coefficient μ changes depending on the contact area ratio (= 15 / surface pressure). As shown in Figure 7(b), the smaller the contact area (i.e., the greater the surface pressure), the smaller the friction coefficient μ. As shown in FIG. 8, the friction coefficient distribution increases toward both ends relative to the center due to changes in the contact area between the lower friction material 424 and the upper friction material 434 and the lower sliding surfaces 241, 242 and the upper sliding surfaces 341, 342.

[0037] As shown in the schematic diagram in Figure 9, the tilt restoring force is determined by the tilt angle θ and is a constant value F = W tan θ, independent of displacement. During an earthquake, the horizontal load changes as shown in [1] to [3] below. [1]0 (at the moment of sliding): μ0W+Wtanθ [2]0~δd:μW+Wtanθ. This range is where the horizontal load increases as the displacement increases. The acceleration is (μ+tanθ)×g. [3]>δd:μ d The result is W+Wtanθ. In this range, even if the displacement is large, the horizontal load is μ d It will never be greater than W+Wtanθ. The acceleration is (μ d +tanθ)×g.

[0038] μ0 is the friction coefficient (initial friction coefficient) when the displacement is 0 (δ=0) (μ(0)=μ0). μ d is the friction coefficient (final friction coefficient) when the displacement is d or more (δ≧δd, when the displacement reaches the constant contact area) (μ(δ)=μ d ). In this embodiment, the initial friction coefficient μ0 is set to the final friction coefficient μ d The friction coefficient μ for δd<δ is set to μ0 to μ d changes linearly to

[0039] In order to suppress residual displacement, the following formula (1) must be satisfied: θ is the inclination angle, and the inclination angles of the lower shoe sliding portion 21 and the upper shoe sliding portion 31 are the same. Gradient tanθ / friction coefficient μ>0.1 (1)

[0040] The fail-safe length exceeding the design displacement δd, that is, the length of the constant contact area portions 24b and 34b, is set to 10 to 20 percent of the design displacement. μ0 / μ d The optimum ratio is 20% or more and 80% or less.

[0041] Next, the operation and effect of the seismic isolation device according to this embodiment will be described. In the seismic isolation device according to this embodiment, the friction between the lower friction material 424 of the slider 4 and the lower sliding surfaces 241, 242 of the lower shoe 2, and the friction between the upper friction material 434 of the slider 4 and the upper sliding surfaces 341, 342 of the upper shoe 3, change depending on the position of the slider 4 relative to the lower shoe 2 and the upper shoe 3. This makes it possible to change the damping according to the response displacement. This eliminates the need to install a damper device, such as a displacement-dependent friction damper or oil damper, separately from the seismic isolation device 1, thereby reducing the effort and costs involved in installation and maintenance.

[0042] The Y-direction dimensions of the lower slide surfaces 241, 242 gradually increase from the center in the X direction toward both ends to a predetermined position, and are set constant from the predetermined position toward both ends in the X direction, while the X-direction dimensions of the upper slide surfaces 341, 342 gradually increase from the center in the Y direction toward both ends to a predetermined position, and are set constant from the predetermined position toward both ends in the Y direction. By adopting such a configuration, the initial friction coefficient μ0 becomes the final friction coefficient μ d Since the acceleration is smaller, the response acceleration can be reduced at an early stage when the lower structure 11 and the upper structure 12 are displaced relative to each other. Near the center of the lower shoe 2 in the X direction and the center of the upper shoe 3 in the Y direction, where the slider 4 is in its original position, the coefficient of friction between the slider 4 and the lower shoe 2 and between the slider 4 and the upper shoe 3 is small, which increases the restoring force and suppresses residual displacement.

[0043] The initial friction coefficient μ0 is the final friction coefficient μ d The friction coefficient μ for δd<δ is set to μ0 to μ d changes linearly to By adopting such a configuration, the response acceleration can be reduced efficiently.

[0044] The seismic isolation device 1 according to this embodiment can suppress response acceleration during small to medium earthquakes (within the design displacement). It is also possible to suppress response displacement to a small value. The seismic isolation device 1 according to this embodiment has a constant friction coefficient even when the design displacement is exceeded, so it can maintain seismic isolation performance. The seismic isolation device 1 according to this embodiment can set an appropriate initial friction for wind resistance. The seismic isolation device 1 according to this embodiment has a constant friction coefficient even when the design displacement is exceeded, so acceleration remains constant, providing a fail-safe.

[0045] (Second embodiment) Next, a second embodiment will be described. The same or similar members and parts as those in the first embodiment will be denoted by the same reference numerals, and the description will be omitted. Only the configurations different from the first embodiment will be described. As shown in Figure 10, the seismic isolation device 1 according to the second embodiment differs from the seismic isolation device 1 according to the first embodiment in the shapes of the lower sliding surfaces 241, 242 and the upper sliding surfaces 341, 343. The Y-direction dimensions of the first lower sliding surface 241 and the second lower sliding surface 242 are set constant from the center in the X direction toward both ends to predetermined positions and gradually decrease from the predetermined positions toward both ends in the X direction. The X-direction dimensions of the first upper sliding surface 341 and the second upper sliding surface 342 are set constant from the center in the Y direction toward both ends to predetermined positions and gradually decrease from the predetermined positions toward both ends in the X direction. In other words, the positions of the contact area changeable range 24a and the contact area constant portion 24b of the lower sliding surfaces 241, 242 are swapped, and the positions of the contact area changeable range 34a and the contact area constant portion 34b of the upper sliding surfaces 341, 342 are swapped.

[0046] The seismic isolation device 1B according to the second embodiment can be configured so that the sliders 4 do not slide against the lower shoe 2 and the upper shoe 3 in response to relatively small wind loads or earthquake loads, so that the seismic isolation function does not work, but the seismic isolation function works in response to large earthquakes.In addition, it can be configured so that it does not slide even in strong winds, so that it does not slide even in small earthquakes.

[0047] An analysis to verify the difference in response and residual displacement between the seismic isolation device according to the first embodiment and a conventional seismic isolation device (inclined sliding bearing) will be described. In a conventional seismic isolation device, the coefficient of friction between the slider and the lower sliding surface is constant over the entire X direction, and the coefficient of friction between the slider and the upper sliding surface is constant over the entire Y direction. Hereinafter, the seismic isolation device according to the first embodiment may be referred to as a "displacement-dependent inclined sliding bearing," and the conventional seismic isolation device may be referred to as a "conventional inclined sliding bearing" or "incline only."

[0048] The analytical model is shown in Figure 11. The analytical model is a one-mass system vibration model. The analysis conditions are as follows: The total weight W of the displacement-dependent inclined sliding bearing and the conventional inclined sliding bearing is 10,700 kN. (1) Conventional inclined sliding bearing Friction coefficient μ d =0.1 (The friction restoring force is shown in Figure 12) Tilt angle θ = 1.5° (the tilt restoring force is shown in Figure 12) (2) Displacement-dependent inclined sliding bearing Friction coefficient μ d = 0.1 (The friction restoring force is the same as that of the conventional inclined sliding bearing shown in Figure 13) Inclination angle θ = 1.5° (the inclination restoring force is shown in Figure 13, the same as that of a conventional inclined sliding bearing) The initial coefficient μ0 is the friction coefficient μ d 20%, 40%, 60%, and 80% of the above.

[0049] The six types of seismic waves used in the analysis are the 1940 El Centro wave (NS component), the 1952 Taft wave (EW component), the 1968 Hachinohe wave (NS component), the Koji wave (Kobe phase), the Koji wave (Kanto phase), and the Koji wave (Hachinohe phase), as shown in Figure 14. Figure 14 also shows the level of each seismic wave.

[0050] The analysis results are shown in Figures 15 to 32. From the graphs of response acceleration for each seismic wave shown in Figures 15 to 20, it can be seen that displacement-dependent inclined sliding bearings have a smaller response acceleration than conventional inclined sliding bearings, and are therefore effective. With displacement-dependent inclined sliding bearings, it can be seen that the smaller the initial friction coefficient (μ0), the smaller the response acceleration. In particular, it can be seen that the effect is greater the smaller the input velocity of the seismic motion (towards the left on the horizontal axis of the graph). Quantitatively, μ0 / μ d When the input speed is set to 75 cm / s, the response acceleration is approximately 60% of that when the input speed is set to 12.5 cm / s, and approximately 30% of that when the input speed is set to 20%. From these facts, μ0 / μ d The ratio is preferably 20% or more and 80% or less.

[0051] From the graphs of response displacement for each seismic wave shown in Figures 21 to 26, it can be seen that the displacement-dependent inclined sliding bearing has a larger response displacement than the conventional inclined sliding bearing. It can also be seen that with displacement-dependent inclined sliding bearings, the smaller the initial friction coefficient (μ0), the smaller the response displacement. It can also be seen that the greater the seismic wave level, the smaller the difference between the displacement-dependent inclined sliding bearing and the conventional inclined sliding bearing.

[0052] From the graphs of residual displacement for each earthquake wave shown in Figures 27 to 32, it can be seen that the displacement-dependent inclined sliding bearing is affected by the type and level of earthquake wave, μ0 / μ d Regardless of the difference in ratio, it can be confirmed that the residual is small, approximately 5 mm or less, just like conventional inclined sliding bearings. From the analysis results of the response acceleration, response displacement, and residual displacement above, it is clear that the design targets of small response acceleration, small response displacement, and small residual displacement are satisfied with μ0 / μ d It is shown that the optimal ratio is between 20% and 80%.

[0053] Although the embodiment of the seismic isolation device according to the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate within the scope of the spirit of the present invention. For example, in the above embodiment, a plurality of seismic isolation devices 1 are provided in the seismic isolation layer 13, but only one may be provided. The plurality of seismic isolation devices 1 provided in the seismic isolation layer 13 may have different forms. It is not necessary that the change in the dimension (width) of the lower slide surfaces 241, 242 in the second horizontal direction and the change in the dimension (width) of the upper slide surfaces 341, 342 in the first horizontal direction be the same. In the above embodiment, the slider 4 is provided with the guide portions 46, 47, but these do not have to be provided. The member that guides the sliding direction of the slider 4 relative to the lower shoe 2 and the upper shoe 3 may be other than the above guide portions 46, 47.

[0054] The Sustainable Development Goals (SDGs) are 17 international goals adopted at the United Nations Summit in September 2015. The seismic isolation device according to this embodiment can contribute to achieving one of the 17 SDGs, for example, goal 9, "Create indispensable infrastructure for industry, innovation and sustainable development." [Explanation of symbols]

[0055] 1,1B Seismic isolation device 2 Lower shoes 3 Upper shoe 4 Slider 11 Undercarriage 12 Superstructure 13 Seismic isolation layer 21 Lower shoe sliding part 24 Lower shoe slide plate 24a Contact area change range 24b Constant contact area 31 Upper shoe sliding part 34 Upper shoe slide 34a Contact area change range 34b Constant contact area part 41 Sliding part 42 Lower sliding surface 43 Upper sliding surface 211 First lower shoe sliding part 212 Second lower shoe sliding part 241 First Lower Slide Surface 242 Second Lower Slide Surface 311 First upper shoe sliding part 312 Second upper shoe sliding part 341 First upper slide surface 342 Second upper sliding surface 422 First lower sliding surface 423 Second Lower Slide Surface 424 Lower friction material 434 Upper friction material

Claims

1. provided between the lower structure and the upper structure which are relatively displaceable in the horizontal direction, a lower shoe fixed on the lower structure; an upper shoe fixed below the upper structure; a slider disposed between the lower shoe and the upper shoe, the slider being displaceable relative to the lower shoe in a first horizontal direction and displaceable relative to the upper shoe in a second horizontal direction perpendicular to the first horizontal direction; a lower sliding surface on which the slider slides is provided, the lower sliding surface being formed in a V-shape that is concave downward and gradually extends upward from the center toward both ends in the first horizontal direction; an upper sliding surface on which the slider slides is formed on a lower surface of the upper shoe, the upper sliding surface being formed in an inverted V-shape that is gradually concave upward from the center toward both ends in the second horizontal direction; The second horizontal dimension of the lower sliding surface is not constant over the entire first horizontal direction, but is set to vary depending on the position in the first horizontal direction; A seismic isolation device in which the first horizontal dimension of the upper sliding surface is not constant throughout the entire second horizontal direction, but is set to vary depending on the position in the second horizontal direction.

2. The second horizontal dimension of the lower sliding surface gradually increases from the center toward both ends in the first horizontal direction to a predetermined position, and is set constant from the predetermined position toward both ends in the first horizontal direction, The dimension of the upper sliding surface in the first horizontal direction gradually increases from the center toward both ends in the second horizontal direction to a predetermined position, and is set constant from the predetermined position toward both ends in the second horizontal direction, In an initial state, the slider is disposed above the center of the lower slide surface in the first horizontal direction and below the center of the upper slide surface in the second horizontal direction; a coefficient of friction between the slider disposed above both ends of the lower slide surface from the predetermined position in the first horizontal direction and the lower slide surface is greater than a coefficient of friction between the slider disposed above the center of the lower slide surface in the first horizontal direction and the lower slide surface; The seismic isolation device described in claim 1, wherein the coefficient of friction between the slider arranged below both ends of the upper slide surface in the second horizontal direction from the specified position of the upper slide surface and the upper slide surface is greater than the coefficient of friction between the slider arranged below the center of the upper slide surface in the second horizontal direction and the upper slide surface.

3. a coefficient of friction between the slider and the lower slide surface increases linearly in proportion to displacement from the center in the first horizontal direction as the slider moves from the center in the first horizontal direction of the lower slide surface toward the predetermined position, The seismic isolation device of claim 2, wherein the coefficient of friction between the slider and the upper sliding surface is set to increase linearly in proportion to the displacement from the center of the second horizontal direction as the slider moves from the center of the second horizontal direction of the upper sliding surface toward the specified position.

4. The second horizontal dimension of the lower sliding surface is constant from the center toward both ends in the first horizontal direction to a predetermined position, and is set so as to gradually decrease from the predetermined position toward both ends in the first horizontal direction, The dimension of the upper slide surface in the first horizontal direction is constant from the center toward both ends in the second horizontal direction to a predetermined position, and is set so as to gradually decrease from the predetermined position toward both ends in the second horizontal direction, In an initial state, the slider is disposed above the center of the lower slide surface in the first horizontal direction and below the center of the upper slide surface in the second horizontal direction; a coefficient of friction between the slider disposed above both ends of the lower slide surface from the predetermined position on the lower slide surface and the lower slide surface is smaller than a coefficient of friction between the slider disposed above the lower slide surface between the center of the lower slide surface in the first horizontal direction and the predetermined position on the lower slide surface and the lower slide surface, and the coefficient of friction between the slider and the lower slide surface is linearly reduced in proportion to the displacement from the center in the first horizontal direction as the slider moves from the predetermined position on the lower slide surface toward both ends of the lower slide surface in the first horizontal direction, The seismic isolation device described in claim 1, wherein the coefficient of friction between the slider arranged below the predetermined position of the upper slide surface in the second horizontal direction and the upper slide surface is smaller than the coefficient of friction between the slider arranged below the upper slide surface between the center of the upper slide surface in the second horizontal direction and the predetermined position and the upper slide surface, and the coefficient of friction between the slider and the upper slide surface decreases linearly in proportion to the displacement from the center in the second horizontal direction as the slider moves from the predetermined position of the upper slide surface toward both ends in the second horizontal direction.

Images