JP5065745B2 - Elastic fixed bearing - Google Patents

Description

  The present invention relates to an elastic fixed bearing that prevents shear deformation from the inside and separates a horizontal load support function and a vertical load support function.

  Some conventional elastic fixed bearings are provided with means for preventing shear deformation from the inside (see Patent Document 1). The elastic fixed support includes a lower steel plate fixed to the lower structure, an upper steel plate fixed to the upper structure, an elastic load supporting plate having an elastic layer interposed between the lower steel plate and the upper steel plate, A central shear key is screwed to the center of the central shear key, and the central shear key is inserted into a through hole having substantially the same diameter as the central shear key provided on the elastic load support plate. A large-diameter portion is screwed on the upper portion of the central shear key, and this engages with an engagement break portion formed on the upper steel plate. Therefore, the central shear key prevents shear deformation of the elastic layer, and supports horizontal force and lifting force generated by an earthquake or the like.

JP 2007-16389 A

  However, only the central shear key resists horizontal force and lifting force generated by an earthquake or the like, and the supporting load is concentrated on the central shear key, so that the durability of the central shear key is shortened. Moreover, since the support function with respect to a horizontal load and a vertical load concentrates on a center shear key, it is necessary to enlarge a center shear key. Accordingly, since the entire elastic fixed support is also increased, the production cost of the elastic fixed support is increased.

  In addition, the elastic layer constituting the elastic load support plate bulges outward in the horizontal direction when a compressive force is applied, and presses in contact with the center shear key, so that the elastic layer is prevented from being deformed in the vertical direction and the elastic function is lowered. To do. Furthermore, since the elastic layer and the central shear key are in contact with each other, the elastic layer is worn due to vertical displacement of the pier or the like, so that deterioration of the elastic layer is promoted and the durability of the elastic layer is shortened.

  The object of the present invention has been made in view of such a problem. By preventing shear deformation of the elastic layer from the inside and reliably separating the horizontal load support function and the vertical load support function, the extension of the durable life and the production are made. An object of the present invention is to provide an elastic fixed bearing capable of reducing costs and ensuring an elastic function during compression.

The elastic fixed support according to claim 1 is fixed to a lower steel plate having a fixed body fixed to a lower structure of a bridge, an upper steel plate engaging body formed on an upper surface of the fixed body, and an upper structure of the bridge. An upper steel plate that is horizontally locked to the upper steel plate locking body of the lower steel plate, and an elastic layer that is fixed around the upper steel plate locking body between the bottom surface of the upper steel plate and the upper surface of the fixing body. And both upper and lower ends of the elastic layer are formed integrally with the lower surface of the upper steel plate and the upper surface of the fixed body by vulcanization, respectively, and between the side surface of the upper steel plate locking body and the elastic layer. A gap larger than the horizontal maximum bulge amount of the elastic layer is formed, the upper steel plate locks to the upper steel plate locking body in all horizontal directions, and at the same time the upper steel plate locking body supports the horizontal load, and the elastic layer is vertical. It is characterized by supporting a load.

Since the upper steel plate is locked by the upper steel plate locking body provided on the upper surface of the lower steel plate, the shear deformation of the elastic layer fixed to the upper steel plate is prevented. Moreover, since the upper steel plate locking body is not restrained by the upper steel plate and the elastic layer, only the horizontal load is supported, and the elastic layer supports only the vertical load. As a result, the support function for the horizontal load and the vertical load is completely separated, and the upper steel plate locking body supports only the horizontal load, so the load acting on the upper steel plate locking body is reduced, and the durable life is extended. At the same time, the size of the upper steel plate locking body is reduced.

  Since the gap formed between the side surface of the upper steel plate locking body and the wall surface of the elastic layer is equal to or greater than the horizontal maximum bulge amount of the elastic layer, the elastic layer does not contact the upper steel plate locking body during compression. . Therefore, the elastic layer can fully exhibit an elastic function, and there is no possibility of deterioration due to wear with the upper steel plate locking body. Furthermore, the elastic fixed bearing is composed of an upper steel plate, an elastic layer, and a lower steel plate, so the number of parts is small, manufacturing is easy, and since it is integrated, on-site assembly work is omitted and installation time is shortened. .

The side surface facing the elastic layer of the upper steel plate locking body is formed on the inner side of the upper steel plate locking body more than the horizontal maximum bulging amount of the elastic layer from the side surface facing the upper steel plate of the upper steel plate locking body. (Claim 2). In this case, when only the portion facing the elastic layer of the upper steel plate locking body is formed to be depressed toward the inside of the maximum horizontal bulge amount of the elastic layer, the elastic layer bulges in the horizontal direction by the compressive force, The state in which the upper steel plate locking body and the upper steel plate are in contact can be maintained. As a result, the horizontal movement of the upper steel plate, that is, the shear deformation of the elastic layer is completely prevented, so that the effective cross section of the elastic layer in the vertical direction due to the shear deformation is prevented from being reduced, and the function of supporting the vertical load does not deteriorate.

The side surface facing the upper steel plate locking body of the elastic layer is formed outside the upper steel plate locking body by more than the horizontal maximum bulging amount of the elastic layer from the side surface of the upper steel plate facing the upper steel plate locking body. (Claim 3). In this case, even if the elastic layer is compressed, the elastic layer does not bulge inward from the upper steel plate, so that the upper steel plate locking member and the upper steel plate abut while the elastic layer bulges in the horizontal direction by the compressive force. The state can be maintained. As a result, since the horizontal movement of the upper steel plate, that is, the shear deformation of the elastic layer, is completely prevented, the effective cross section of the elastic layer in the vertical direction due to the shear deformation is prevented from being reduced, and the function of supporting the vertical load is not deteriorated.

  As described above, the present invention includes a lower steel plate, an elastic layer, and an upper steel plate, a gap larger than the horizontal maximum bulge amount of the elastic layer is formed between the upper steel plate locking body and the elastic layer, and the horizontal load is related to the upper steel plate. Since the stationary body supports and the elastic layer supports the vertical load, the durability can be extended, the manufacturing cost can be reduced, and the elastic function at the time of compression can be ensured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows an example of a bridge 1 in which the elastic fixed support 4 of the present invention is implemented. The bridge 1 is a continuous beam, and includes an upper structure 2 having a floor board, a steel girder, etc., three lower structures 3 such as piers and abutments, and an elastic fixing interposed between the upper structure 2 and the lower structure 3. It consists of a support 4 and is fixed at a multipoint where one superstructure 2 is supported by three fulcrums.

As shown in FIG. 2, a plurality of elastic fixed supports 4 are arranged, for example, in a direction perpendicular to the bridge axis (three at regular intervals in FIG. 2). As shown in FIGS. 3A and 3B, the elastic fixed support 4 includes an upper steel plate 10, a lower steel plate 11, and an elastic layer 12, and these surfaces are covered with a covering member 13 such as CR. The upper steel plate 10 is fixed to the upper structure 2 via the plate 16, and the lower steel plate 11 is fixed to the lower structure 3 via the saddle mortar 9, and the elastic layer 12 is interposed between the upper steel plate 10 and the lower steel plate 11. Yes.

  The lower structure 3 has one end where a male screw portion 6a of the anchor bolt 6 is formed by filling the anchor bolt insertion hole 3b drilled from the upper surface 3a with a hardening material 5 such as non-shrink mortar and integrating it with the anchor bolt 6. The portion protrudes from the upper surface 3 a of the lower structure 3.

  The lower steel plate 11 has a fixed body 11a fixed to the lower structure 3 and an upper steel plate locking body 11b formed at the center of the upper surface of the fixed body 11a. As shown in FIG. 4, the fixed body 11 a is, for example, a steel plate having a rectangular outer contour, and is disposed such that the direction perpendicular to the bridge axis coincides with the long side direction. As shown in FIG. 4, anchor bolt insertion holes 11c are provided at four corners of the fixed body 11a, and the anchor bolt 6 is inserted into the anchor bolt insertion holes 11c as shown in FIG. 11 a is placed on the upper surface 3 a of the lower structure 3. A nut 7 is screwed onto the male thread portion 6 a of the anchor bolt 6, and the lower structure 3 and the lower steel plate 11 are fixed.

  As shown in FIG. 5, the upper steel plate locking body 11b is a rectangular parallelepiped made of steel, for example, in plan view, and is integrated with the fixed body 11a. The plan view shape of the upper steel plate locking body 11b is not limited to a square, but is desirably a square or a rectangle for ease of manufacture. The choice of square or rectangle depends on the designed length in the direction of the bridge axis and the length in the direction perpendicular to the bridge axis, and the length in the direction of the bridge axis and the length in the direction perpendicular to the bridge axis depend on the magnitude of the expected earthquake and the elastic fixed bearing. 4 is determined by the design horizontal load calculated from the number of installed 4 and the like.

  The upper steel plate 10 is, for example, a square steel plate with an outer contour square provided with a square upper steel plate locking body insertion port 10a penetrating in the center. The shape of the upper steel plate locking body insertion port 10a is not limited to a square, but may be any shape as long as the upper steel plate locking body 11b can be inserted. However, when the gap between the upper steel plate locking body 11b and the upper steel plate locking body insertion port 10a becomes large, moisture, dust, etc. enter and each member is likely to deteriorate, so the same shape as the upper steel plate locking body 11b It is preferable that

  The installation location of the upper steel plate locking body insertion port 10a does not have to be the central portion, and may be a position corresponding to the upper steel plate locking body 11b at an appropriate relative position between the upper steel plate 10 and the lower steel plate 11. Further, female screw holes 10b are provided at the four corners of the upper surface of the upper steel plate 10, and male screws 8 inserted through the bolt holes of the upper structure 2 are screwed into the female screw holes 10b via the plates 16 to be connected to the upper structure 2 and the upper structure 2. A steel plate 10 is fixed.

  As shown in FIG. 6, the elastic layer 12 is a laminated rubber having a rectangular shape in plan view in which an upper steel plate engaging body insertion hole 12 a having a square cross section perpendicular to the axis of the elastic layer 12 is provided at the center. The elastic layer 12 is preferably a laminated rubber having excellent performance as an elastic bearing. The laminated rubber which is the elastic layer 12 has the rubber bodies 14 and the steel plates 15 laminated alternately, and the contact surface is bonded. Both ends of the elastic layer 12 in the axial direction are composed of rubber bodies 14, and the upper and lower rubber bodies 14 are formed integrally with the lower surface of the upper steel plate 10 and the upper surface of the fixed body 11a by vulcanization molding, respectively.

  The shape of the upper steel plate locking body insertion hole 12a is not limited to a square, but may be any shape as long as the upper steel plate locking body 11b can be inserted. The installation location of the upper steel plate locking body insertion hole 12a does not have to be the central portion, and may be a position corresponding to the upper steel plate locking body 11b at an appropriate relative position between the upper steel plate 10 and the elastic layer 12. In addition, as will be described later, the elastic layer 12 supports the vertical load acting on the bridge 1 while having an elastic function even during an earthquake, and further absorbs the rotational force in the bridge axis direction and the direction perpendicular to the bridge axis. The rubber body 14 is formed thicker than the steel plate 15. As an example, when the thickness of the upper steel plate is 40 mm and the thickness of the fixed body 11a is 40 mm, it is preferable that the rubber body has a thickness of 7 mm and the steel plate has a thickness of about 3.2 mm.

  The elastic fixed support 4 includes a bottom surface of the fixed body 11a, an upper surface outside the elastic layer 12 of the fixed body 11a, an outer surface of the elastic layer 12 and the upper steel plate 10, an upper surface of the upper steel plate 10, and the upper steel plate 10 and the elastic layer 12. The inner surface, the upper surface of the fixed body 11a between the upper steel plate locking body 11b and the elastic layer 12, the side surface and the upper surface of the upper steel plate locking body 11b are covered with the covering member 13 to prevent the rust. It has been subjected. However, although the covering member 13 is not covered with the female screw hole 10b and the anchor bar insertion hole 11c, a rust prevention treatment is performed. For example, the thickness of the portion covering the outer surface of the elastic layer 12 and the upper steel plate 10 is 10 mm, the thickness of the portion covering the inner surface of the elastic layer 12 and the upper steel plate 10 is 5 mm, and the other portion is about 2 mm. is there. As described above, the elastic layer 12 faces the outside in the use state, and the outer surface portion of the upper steel plate 10 and the elastic layer 12 that easily deteriorates are particularly thickened.

  The elastic fixed support 4 integrated in this way is manufactured at the factory, and is only placed at a predetermined position after delivery and screwed with a male screw or a nut. Therefore, the assembly work at the site is reduced and the work time is reduced. Is shortened. The covering member 13 needs to be soft enough not to impede the compressive deformation by restraining the horizontal bulging of the rubber body when the elastic layer 12 is compressed so as not to lower the elastic function of the elastic layer 12.

  In the present embodiment, the upper steel plate 10 and the elastic layer 12 are formed in the same shape and the same size in plan view, and the side surfaces are flush with each other. The horizontal distance L1 of the side surface is equal to the horizontal distance L2 between the side surface of the upper steel plate locking body 11b and the inner side surface of the upper steel plate 10. The horizontal distances L1 and L2 are slightly larger (about 7 to 8 mm) than the horizontal maximum bulge amount of the elastic layer 12.

  This is because when the covering member 13 covering the inner surface of the elastic layer 12 and the upper steel plate 10 is deformed to the upper steel plate locking body 11b side in conjunction with the compression of the elastic layer 12, the opposing covering member 13 This is because they do not touch. Therefore, the horizontal distance L1 between the side surface of the upper steel plate locking body 11b and the inner side surface of the elastic layer 12 is the horizontal maximum bulge amount, and the covering member 13 of the portion covering the elastic layer 12 and the inner side surface of the upper steel plate 10. It is enough to secure enough to match the thickness of the.

  The height of the upper steel plate locking body is formed to be lower than the combined size of the minimum thickness of the elastic layer 12 and the thickness of the upper steel plate 10 when the elastic layer 12 receives the maximum compressive force. That is, a space is always formed above the upper steel plate locking body 11b.

  As a result, the elastic layer 12 is restrained by being pressed against the upper steel plate locking body 11b via the covering member 13, and the elastic layer 12 is prevented from being deformed in the vertical direction and the elastic function is not lowered. Furthermore, since the upper steel plate locking body 11b is not restrained in the vertical direction, the elastic layer 12 has a function of supporting the vertical load and absorbing the vertical load at all times including during an earthquake.

  Further, since the upper steel plate 10 and the elastic layer 12 surround the upper steel plate engaging body 11b under any circumstances, the upper steel plate 10 is engaged with the upper steel plate 10 in the bridge axis direction and the direction perpendicular to the bridge axis, that is, in all horizontal directions. The body 11b is locked in the horizontal direction. In other words, shear deformation of the elastic layer 12 fixed to the upper steel plate 10 and interlocking with the horizontal displacement of the upper steel plate 10 is prevented.

  Furthermore, since the vertical support portion which is the elastic layer 12 is fixed and restrained to the upper steel plate 10 and the lower steel plate 11, the design vertical seismic force is reduced.

(Embodiment 2)
Next, as shown in FIG. 7, the elastic fixed support 24 which is other embodiment is demonstrated. However, the same names and symbols are used for portions common to the first embodiment, and description thereof is omitted.

  The lower steel plate 31 has a fixed body 31a fixed to the lower structure 3 and an upper steel plate locking body 31b formed at the center of the upper surface of the fixed body 31a. The upper steel plate locking body 31 b includes a base portion 31 c that faces the upper steel plate 10 in the horizontal direction and a diameter-expanded portion 31 d that faces the elastic layer 12 in the horizontal direction. The cross section perpendicular to the axis of the upper steel plate locking body 31b of the base portion 31c and the enlarged diameter portion 31d is a square. As in the first embodiment, the upper steel plate 10, the lower steel plate 31, and the elastic layer 12 are covered with the covering member 33.

  As shown in FIG. 8, the covering member 33 of the portion covering the side surface of the enlarged diameter portion 31d and the covering member 33 of the portion covering the inner surface of the upper steel plate 10 are almost in contact with each other, and the inner space is 1 to It is about 2 mm. The base portion 31c has a horizontal maximum distance L3 between the side surface of the base portion 31c and the inner side surface of the elastic layer 12, and the horizontal distance L4 between the side surface of the enlarged diameter portion 31d and the inner side surface of the upper steel plate 10, It is formed so as to increase the amount.

  Therefore, even when the maximum compressive force is applied to the elastic fixed support 24, the covering member 33 between the elastic layer 12 and the upper steel plate locking body 31b comes into contact, and the elastic layer 12 is inserted into the upper steel plate locking body 31b. Therefore, vertical deformation is not hindered. On the other hand, since the upper steel plate 10 and the enlarged diameter portion 31d are almost in contact with each other via the covering member 33, the upper structure 2 can be completely restrained, and shear deformation of the elastic layer 12 is prevented. As a result, reduction of the effective cross section due to shear deformation of the elastic layer 12 is prevented, so that the vertical support function of the elastic layer 12 can be maintained.

(Embodiment 3)
Next, as shown in FIG. 9, the elastic fixed support 44 which is other embodiment is demonstrated. However, the same names and symbols are used for portions common to the first embodiment, and description thereof is omitted.

  As shown in FIG. 9, for example, a steel plate having a square outer contour provided with a square upper steel plate engaging body insertion port 50 a penetrating in the center. The elastic layer 52 is a laminated rubber having a rectangular shape in a plan view in which an upper steel plate engaging body insertion hole 52a having a square cross section perpendicular to the axis of the elastic layer is provided at the center. As in the first embodiment, the upper steel plate 50, the lower steel plate 11, and the elastic layer 52 are covered with the covering member 53.

  As shown in FIG. 10, both the upper steel plate locking body insertion port 50a and the upper steel plate locking body insertion hole 52a are square in cross section perpendicular to the axis of the upper steel plate locking body 11b, but are different in size. . The inner surface of the elastic layer 52 is formed from the inner surface of the upper steel plate 50 to the horizontal maximum bulge amount of the rubber body 54 of the elastic layer 52 and to the outer side of the upper steel plate locking body 11b. That is, the horizontal distance L5 between the side surface of the upper steel plate locking body 11b and the inner side surface of the elastic layer 52 is greater than the horizontal distance L6 between the side surface of the upper steel plate locking body 11b and the inner side surface of the upper steel plate 50. It is formed so as to increase the horizontal maximum bulge amount. Here, the horizontal distance L6 between the side surface of the upper steel plate locking body 11b and the inner side surface of the upper steel plate 50 is the portion of the covering member 53 that covers the side surface of the upper steel plate locking body 11b and the inner side surface of the upper steel plate. The distance between the covering members 53 of the covered portion is about 1 to 2 mm.

  Therefore, even when the maximum compressive force is applied to the elastic fixed support 44, the covering member 53 between the elastic layer 52 and the upper steel plate locking body 11b comes into contact, and the elastic layer 52 is inserted into the upper steel plate locking body 11b. Therefore, vertical deformation is not hindered. On the other hand, since the upper steel plate 50 and the upper steel plate locking body 11b are almost in contact via the covering member 53, the upper structure 2 can be completely restrained, and shear deformation of the elastic layer 52 is prevented. As a result, reduction of the effective cross section due to shear deformation of the elastic layer 52 is prevented, so that the vertical support function of the elastic layer 52 can be maintained.

(Other embodiments)
As described above, the elastic fixed bearings 4, 24, and 44 can be applied not only to a continuous beam but also to a simple beam. Further, the superstructure 2 can be applied to a PC girder in addition to a steel girder. In this case, the upper steel plates 10 and 50 are fixed not by the upper structure 2 and the male screw 8 but by anchor bolts or the like embedded in the PC girder.

  The upper steel plate locking bodies 11b and 31b can be installed in addition to being installed at the center of the upper surface of the fixed bodies 11a and 31a. What is necessary is just to install in the upper surface of the fixed bodies 11a and 31a.

  The upper steel plates 10 and 50 are not limited to the upper steel plate engaging body insertion ports 10a and 50a formed through the upper steel plates 10 and 50, and the upper surfaces of the upper steel plates 10 and 50 may be closed. 44, the upper steel plate locking bodies 11b and 31b may not be restrained in the vertical direction even if the maximum compressive force is applied to.

  Further, the lower steel plate having the upper steel plate locking bodies 11b and 31b is fixed to the lower structure 3, and the upper steel plates 10 and 50 having the upper steel plate locking body insertion ports 10a and 50a are fixed to the upper structure 2. On the contrary, the lower steel plates 11 and 31 may be fixed to the upper structure 2 and the upper steel plates 10 and 50 may be fixed to the lower structure 3. In this case, the means fixed to the upper structure 2 and the lower structure 3 are not interchanged.

It is a side view showing a mode that the elastic fixed support was formed in the bridge. It is AA sectional drawing of FIG. (A) is a longitudinal sectional view in the direction of the bridge axis of the elastic fixed support in FIG. 1, (b) is a front view and a longitudinal sectional view in the direction perpendicular to the bridge axis of the elastic fixed support in FIG. The right side of the drawing is a longitudinal sectional view. It is a principal part enlarged view of Fig.3 (a). It is a top view of an elastic fixed support. It is a bottom view of an elastic fixed support. (A) is a longitudinal sectional view in the bridge axis direction of the elastic fixed support according to the second embodiment, and (b) is a front view and a vertical sectional view in the direction perpendicular to the bridge axis of the elastic fixed support according to the second embodiment. Is a front view, and the right side of the drawing is a longitudinal sectional view. It is a principal part enlarged view of Fig.7 (a). (A) is a longitudinal sectional view in the bridge axis direction of the elastic fixed support of Embodiment 3, and (b) is a front view and a longitudinal sectional view of the elastic fixed support of Embodiment 3 in the direction perpendicular to the bridge axis, and is on the left side of the drawing. Is a front view, and the right side of the drawing is a longitudinal sectional view. It is a principal part enlarged view of Fig.9 (a).

Explanation of symbols

1 ... Bridge 2 ... Upper structure 2a ... Upper structure bottom surface 3 ... Lower structure 3a ... Lower structure upper surface 3b ... Anchor bolt insertion hole 4 ... Elastic fixed support 5 ... Hardened Material 6 ... Anchor bolt 6a ... Male screw part 7 ... Nuts 8 ... Male screw 9 ... ... Saddle mortar 10 ... Upper steel plate 10a ... Upper steel plate locking member insertion port 10b ... Female screw hole 11 ... Lower steel plate 11a ... fixed body 11b ... upper steel plate locking body 11c ... anchor bolt insertion hole 12 ... elastic layer 12a ... upper steel plate locking body insertion hole 13 ... cover member 14 ... rubber body 15 ... steel plate 16 ... Plate 24 ... Elastic fixed support 31 ... Lower steel plate 31a ... Fixed body 31b ... Upper steel plate locking body 31c ... Base 31d ... Diameter enlarged portion 31c ... Anchor bolt insertion hole 33 ... Cover member 44 ... Elastic fixed support 50 ... ... Upper steel plate 50a ... Upper steel plate engaging member insertion slot 5 ...... Elastic layer 52a ... Upper steel plate locking body insertion hole 53 ... Cover member 54 ... Rubber body 55 ... Steel plate L1 ... Horizontal distance L2 between the side surface of the upper steel plate locking body and the inner side surface of the elastic layer ... Horizontal distance L3 between the side surface of the steel plate locking body and the inner side surface of the upper steel plate: Horizontal distance L4 between the side surface of the base and the inner side surface of the elastic layer: Horizontal distance L5 between the side surface of the enlarged diameter portion and the inner side surface of the upper steel plate. Horizontal distance L6 between the side surface of the upper steel plate locking body and the inner side surface of the elastic layer .... The horizontal distance between the side surface of the upper steel plate locking body and the inner side surface of the upper steel plate.

Claims (3)

A lower steel plate provided with a fixed body fixed to the lower structure of the bridge, and an upper steel plate locking body formed on the upper surface of the fixed body;
An upper steel plate fixed to the upper structure of the bridge, and horizontally locked to the upper steel plate locking body of the lower steel plate;
Between the bottom surface of the upper steel plate and the upper surface of the fixed body, and having an elastic layer fixed around the upper steel plate locking body,
Both upper and lower ends of the elastic layer are formed integrally with the lower surface of the upper steel plate and the upper surface of the fixed body by vulcanization,
Between the side surface of the upper steel plate locking body and the elastic layer, a gap greater than the horizontal maximum bulge amount of the elastic layer is formed,
An elastic fixed bearing, wherein the upper steel plate is locked to the upper steel plate locking body in all horizontal directions and simultaneously supports a horizontal load, and the elastic layer supports a vertical load.   The side surface of the upper steel plate locking body facing the elastic layer is more than the horizontal maximum bulge amount of the elastic layer from the side surface of the upper steel plate locking body facing the upper steel plate. The elastic fixed bearing according to claim 1, wherein the elastic fixed bearing is formed inward. The side surface of the elastic layer facing the upper steel plate locking body is equal to or greater than the horizontal maximum bulging amount of the elastic layer from the side surface of the upper steel plate facing the upper steel plate locking body. The elastic fixed bearing according to claim 1, wherein the elastic fixed bearing is formed outward.

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