JP4819174B2 - Elastic load support - Google Patents

Description

  The present invention relates to an elastic load support, and more particularly to an elastic load support incorporated as a main body in a support installed between an upper structure and a lower structure in a bridge.

  The functions required for the support using the elastic load support mainly composed of rubber include a vertical load support function for transmitting the load of the upper structure to the lower structure and a rotation function for enabling the rotation of the upper structure. Since rubber has the property of being compressed and deformed by elasticity when subjected to a load, the latter rotation function utilizes the elasticity of rubber. On the other hand, regarding the vertical load support function, the elastic load support body needs to generate a vertical strain that does not generate a tensile stress in the rubber in order to follow the upper structure when it rotates.

  When vertical strain is generated in the elastic load support, the rubber does not change in volume even if it is deformed. Therefore, as shown in FIG. (R represents a vertical load). This bulging of the rubber generates a local shear stress in the rubber and brings about an adverse effect. Therefore, it is desirable that the amount of bulging is as small as possible even when vertical strain occurs. From the above, the elastic load support mainly composed of rubber has to be designed so that the surface pressure received by the vertical load is reduced and the swelling is reduced. As a result, the elastic load support becomes large and the entire support becomes large.

  Patent Documents 1 and 2 disclose elastic load supports that achieve a high surface pressure. In this elastic load support, an annular reaction force wall is provided on the outer periphery of the upper and lower steel plates sandwiching the rubber layer, and an annular recess is provided on the outer periphery of the rubber layer. This elastic load support restrains the shear force generated in the rubber layer by the vertical load by the reaction wall, and makes the annular recess absorb the swelling of the rubber layer, thereby to withstand high surface pressure. ing.

JP 11-236944 A JP 2004-308109 A

The present invention has been made based on the technical background as described above, and achieves the following object.
An object of the present invention is to provide an elastic load support capable of increasing the surface pressure of the elastic load support, thereby reducing the size of the entire support and reducing the cost.

  When a vertical load acts on the elastic load support, the surface pressure distribution of the elastic load support is not constant, and as shown in FIG. 11, the surface pressure becomes maximum as the central portion reaches the outer peripheral portion. The inventor of the present invention paid attention to this surface pressure distribution as a result of intensive studies in order to solve the above problems. Then, if the vertical stiffness distribution of the elastic load support is in accordance with the surface pressure distribution, that is, if the vertical stiffness is increased in the central portion and the vertical stiffness is reduced toward the outer peripheral portion, the high surface pressure is increased. It has been found that it is easy to rotate because of its low vertical rigidity at the outer periphery.

The present invention has been made on the basis of the above knowledge, and employs the following means.
That is, the present invention is an elastic load support in which a rubber layer is formed between an upper steel plate and a lower steel plate,
At least one of the lower surface of the upper steel plate and the upper surface of the lower steel plate has a curved surface so that the thickness of the rubber layer gradually increases from the central portion to the outer peripheral portion ,
The outer peripheral portion of the curved surface is in an elastic load support having a radius of curvature smaller than that of other portions .

  The elastic load support is incorporated into a bridge support installed between the superstructure and the substructure. The bearing is a sliding bearing, and a sliding material is provided on the upper part of the upper steel plate. Alternatively, the support is a fixed support, and a through hole for inserting a shear key for transmitting a horizontal force between the upper and lower structures is provided at the center of the elastic load support.

  According to the present invention, since the thickness of the rubber layer is gradually increased from the central portion to the outer peripheral portion, the elastic load support has a large primary shape factor in the central portion, that is, the vertical rigidity is large, and the vertical rigidity is increased toward the outer periphery. Get smaller. Accordingly, the vertical stiffness distribution corresponds to the surface pressure distribution, and the elastic load support can withstand high surface pressure while generating vertical strain necessary for rotation. At the same time, the swelling of rubber can be suppressed, and the occurrence of local shear strain in the outer peripheral portion can be reduced. Thereby, an elastic load support body can be made small in area and height, the entire bearing can be made compact, and cost reduction can be achieved.

It is sectional drawing which shows embodiment of the elastic load support body by this invention. It is a top view which reduces and shows the thing of the same embodiment. It is a bridge axis perpendicular direction sectional view showing the slide bearing to which the thing of the embodiment is applied. It is a bridge axis direction sectional view of the sliding bearing. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. It is sectional drawing which shows another embodiment of an elastic load support body. It is a top view which reduces and shows the thing of the same embodiment. It is sectional drawing which shows another embodiment of an elastic load support body. It is a top view which reduces and shows the thing of the same embodiment. It is a bridge axial direction sectional view showing the fixed bearing to which the thing of the embodiment is applied. It is a figure which shows the surface pressure distribution at the time of a vertical load acting on an elastic load support body. It is a figure which shows the swelling phenomenon of rubber | gum when a vertical load acts on an elastic load support body.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the elastic load support 1 includes an upper steel plate 2, a lower steel plate 3, and a rubber layer 4 disposed between the upper and lower steel plates 2 and 3. The elastic load support 1 is formed in a cylindrical shape that is a planar circle or a prismatic shape that is a planar rectangle. In this embodiment, the elastic load support 1 is a circular plane, and the upper and lower steel plates 2 and 3 are both circular.

  The lower steel plate 3 is a normal steel plate having a required thickness that is flat on both the upper and lower surfaces. On the other hand, the upper steel plate 2 has a flat upper surface but a lower curved surface 5 on the lower surface. As a result, the thickness of the rubber layer 4 gradually increases from the center portion to the outer peripheral portion of the load support 1. Therefore, the rubber layer 4 has the smallest thickness at the center. The thickness change of the rubber layer 4 is defined by the curved surface 5 of the upper steel plate 2. The shape of the curved surface 5 can take various shapes, but a shape in which the thickness change of the rubber layer 4 is not large, for example, a shape in which the vertical cross section is a parabolic shape is desirable. However, the outer peripheral portion 5a of the curved surface 5 has a smaller radius of curvature than the other portions.

  The elastic load support 1 is made by vulcanizing and bonding the upper and lower steel plates 2 and 3 and the rubber layer 4 in the same manner as a known laminated rubber. As a material for the rubber layer 4, chloroprene-based synthetic rubber or natural rubber can be used, but it is desirable to use natural rubber from the viewpoint of fatigue resistance. The outer periphery of the elastic load support 1 is covered with a covering rubber layer 6.

  3 to 5 show a use example in which the elastic load support 1 is incorporated as a main body (rubber rod) of a sliding bearing in a bridge. A rectangular sole plate 13 having a boss hole 14 at the center is fixed to the lower surface of the flange 12 of the bridge girder 11 (steel girder), which is an upper structure, by welding. An upper rod 15 made of a rectangular steel plate is fixed to the lower surface of the sole plate 13 by bolts 17. The upper collar 15 has a shear key 16 that fits into the boss hole 14.

  A stainless steel plate 18 as a sliding member is provided on the lower surface of the upper collar 15. The stainless steel plate 18 is fitted into a recess formed on the lower surface of the upper collar 15 so that the surface thereof is flush with the upper collar 15, and is fixed to the upper collar 15 by welding. Notches 20 and 20 having step portions 19 extending in the bridge axis direction are formed on both sides of the upper rod 15 in the bridge axis direction (X direction).

  A lower rod 21 made of a rectangular steel plate is fixed to the upper surface of the pier 22 which is a lower structure via an anchor bolt 23. Side blocks 24, 24 are detachably fixed to both sides of the lower rod 21 in the bridge axis direction via fixing bolts 25. The side block 24 has an overhang portion 26 at the upper end, and the overhang portion 26 is loosely engaged with the step portion 19 of the upper collar 15. By this engagement, the movement of the bridge girder 11 in the direction perpendicular to the bridge axis (Y direction) and the lifting movement of the bridge girder 11 are restricted.

  The elastic load support 1 according to the present invention is placed on the upper surface of the lower collar 21. The lower collar 21 is provided with a plurality of displacement prevention plates 28 for suppressing the displacement of the elastic load support 1 and positioning it so as to be positioned on the outer periphery of the lower end portion of the elastic load support 1.

  An intermediate plate 30 made of a square steel plate is placed on the upper surface of the elastic load support 1. A Teflon (registered trademark, hereinafter the same) plate 32 as a sliding member is provided on the upper surface of the intermediate plate 30, and the Teflon plate 32 is slidably pressed against the stainless steel plate 18. The Teflon plate 32 is formed in a flat circular shape like the elastic load support 1, and is fitted into a recess formed on the upper surface of the intermediate plate 30 and bonded thereto. In this state, the surface of the Teflon plate 32 protrudes from the upper surface of the intermediate plate 30.

  Both sides 31, 31 of the intermediate plate 30 in the bridge axis direction protrude from the upper surface of the elastic load support 1. Cutouts 34, 34 are formed on both side parts 31, 31. The side blocks 24 and 24 are loosely fitted and engaged with the notches 34 and 34.

  In the sliding bearing as described above, when a horizontal load acts on the upper structure 11 due to an earthquake or the like, the upper structure 11 moves in the bridge axis direction. At that time, a horizontal load is also applied to the intermediate plate 30 through the frictional force between the stainless steel plate 18 and the Teflon plate 32. However, the intermediate plate 30 is engaged and restrained by the side block 24, so that it moves. Can not do it. Therefore, the horizontal movement of the bridge girder 11 is realized only by sliding between the stainless steel plate 18 and the Teflon plate 32 against the frictional force, and no horizontal load is transmitted to the elastic load support 1, and shear deformation is performed. Will not cause.

  The elastic load support 1 does not have a function of transmitting a horizontal load, but has a function of transmitting the vertical load of the upper structure 11 to the lower structure 22 and a function of following the rotation of the upper structure 11. As described above, the elastic load support 1 has the thinnest rubber layer 4 at the center, and gradually increases toward the outer periphery. This means that the elastic load support 1 has a large primary shape factor at the center, that is, the vertical rigidity is large, and the vertical rigidity decreases as it goes to the outer periphery. This means that it has a vertical stiffness distribution corresponding to the surface pressure distribution described with reference to FIG.

  Therefore, the elastic load support 1 has a lower rubber layer and can withstand high surface pressure than a known laminated rubber having a required thickness necessary for the rotation function of the rubber layer. At the same time, the swelling of the rubber can be suppressed, and the occurrence of local shear strain in the outer peripheral portion can be prevented. In particular, the curved surface 5 of the upper steel plate 2 has a small radius of curvature of the outer peripheral portion 5a. Therefore, even if rubber bulges due to bearing stress, the bulge is absorbed in the outer peripheral portion, and FIG. As shown in b), the bulging amount δ can be made as small as possible as compared with the conventional one shown in FIG. On the other hand, regarding the rotation function, the rubber layer 4 is thick at the outer peripheral portion, so that the vertical rigidity is small and the deflection is easy, and the rotation is smooth.

Incidentally, the case of the equal thickness of the rubber layer of the elastic load support, but unable or 8~12N / mm ² approximately of the surface pressure, according to the above embodiments, as high as 20~25N / mm ² surface Pressure can be taken. Therefore, the elastic load support 1 can be made small in area and height, and the entire support can be made compact, and the cost can be reduced. In particular, when applied to the sliding bearing as described above, since the height of the elastic load support 1 is reduced, the side block 24 can also be designed to be small.

  6 and 7 show another embodiment of the elastic load support 1 according to the present invention. This elastic load support 1 is also incorporated as a main body (rubber rod) in the sliding bearing shown in FIGS. The lower surface of the upper steel plate 2 is a convex curved surface 5 similar to that of the embodiment, although the curvature radius is extremely larger than that of the embodiment shown in FIGS. The upper surface 9 of the lower steel plate 3 is a flat surface. Therefore, the thickness of the rubber layer 4 is gradually increased from the central portion to the outer peripheral portion of the load support 1. In this embodiment, the outer peripheral portion 5a of the lower surface 5 of the upper steel plate 1 is a curved surface 5a having a small radius of curvature that continues to the upper surface. Moreover, the outer peripheral part 9a of the upper surface 9 of the lower steel plate 3 is also a curved surface 9a having a small curvature radius that continues to the lower surface. Therefore, similarly to the embodiment, the elastic load support 1 can absorb rubber bulge at the outer peripheral portion, and can rotate smoothly.

  8 and 9 show still another embodiment of the elastic load support 1 according to the present invention. In this embodiment, the elastic load support 1 is provided with a through hole 7 in the center. Therefore, the upper and lower steel plates 2 and 3 and the rubber layer 4 are annular. The inner periphery of the elastic load support 1 is covered with a covering rubber layer 8. Further, the inner peripheral portion 5b of the upper steel plate 2 having the curved surface 5 has a small radius of curvature in order to prevent the rubber from bulging. Other configurations are the same as those of the embodiment shown in FIGS. As shown in FIG. 10, the elastic load support 1 is incorporated as a main body (rubber rod) of a fixed support for a bridge.

  The fixed support includes a rectangular sole plate 13 fixed to the lower surface of the upper structure 11 by welding, and a rectangular (or circular) lower collar 21 fixed to the lower structure 22. The lower rod 21 is fixed to the lower structure 22 via a plurality of anchor bolts 23 embedded in the lower structure 22. The anchor bolt 23 is of a type in which the upper end of the anchor bolt 23 is fastened to the lower collar 21 by screws 6 from below, and does not protrude from the upper surface of the lower collar 21. For this reason, the elastic load support 1 can be installed at any position on the lower rod 21.

  A rectangular intermediate plate 35 is fixed to the lower surface of the sole plate 13. The intermediate plate 35 is fixed to the sole plate 13 by set bolts 36 attached to the upper structure 11. The elastic load support 1 is installed between the intermediate plate 35 and the lower collar 21. The elastic load support 1 is placed between the intermediate plate 35 and the lower collar 21.

  The intermediate plate 35 is formed with a through hole 38 aligned with the through hole 7 of the elastic load support 1 at the center thereof, and a cylindrical shear key 39 is disposed in the through holes 7 and 38. The shear key 39 is made of a cast steel product integrally formed with the lower iron 21. A corner R39a is provided on the base (base) of the shear key 39 over the entire circumference. The outer diameter of the shear key 39 is smaller than the hole diameter of the through holes 7 and 38, and therefore a gap is formed between the shear key 39 and the peripheral walls of the through holes 7 and 38. A male screw 40 is provided above the shear key 39, and a ring nut 41 constituting a flange is fixed to the male screw 40.

  The sole plate 13 is formed with a fitting hole 42 concentric with the through holes 7 and 38. The flange 41 is fitted into the fitting hole 42. The fitting hole 42 has a larger diameter than the through holes 7 and 38, and therefore, the lower surface of the flange 41 can be engaged with the intermediate plate 35. The outer periphery of the flange 41 is a convex curved surface, and gaps are formed between the lower surface of the flange 41 and the intermediate plate 35 and between the upper surface of the flange 41 and the upper structure 11.

  In the fixed support, the vertical load of the upper structure 11 is elastically supported by the elastic load support 1. The horizontal load of the upper structure 11 is directly transmitted from the sole plate 13 to the flange 41 of the shear key 39 and further transmitted to the lower structure 22 via the shear key 39 and the lower rod 21 integrated therewith. Thereby, the horizontal displacement of the upper structure 11 is restrained, and the support using the elastic load support 1 functions as a fixed support. A horizontal load does not act on the elastic load support 1.

  As described above, there are gaps between the shear key 39 and the peripheral walls of the through holes 7 and 38, between the lower surface of the flange 41 and the intermediate plate 35, and between the upper surface of the flange 41 and the upper structure 11. In addition, since the outer periphery of the flange 41 is a convex curved surface, the elastic load support 1 can follow the vertical rotation of the upper structure 11. Further, when the upper lifting force acts on the upper structure 11, the intermediate plate 35 engages with the lower surface of the flange 41, so that the upper lifting force can be suppressed.

  Even in this form of use, the elastic load support 1 does not have a function of transmitting a horizontal load, but has a function of transmitting the vertical load of the upper structure 11 to the lower structure 22 and a function of following the rotation of the upper structure 11. have. And also in this usage mode, since the elastic load support body 1 can endure high surface pressure, the above-mentioned effects can be obtained. That is, the elastic load support 1 can be made small, the entire support can be made compact, and the cost can be reduced.

  The above-described embodiment or usage pattern is merely an example, and the present invention can take various aspects. For example, in the above two embodiments, the lower surface of the upper steel plate is curved, but the upper surface of the lower steel plate may be curved. Alternatively, both the lower surface of the upper steel plate and the upper surface of the lower steel plate may be curved.

DESCRIPTION OF SYMBOLS 1 Elastic load support body 2 Upper steel plate 3 Lower steel plate 4 Rubber layer

Claims (4)

An elastic load support in which a rubber layer is formed between an upper steel plate and a lower steel plate,
At least one of the lower surface of the upper steel plate and the upper surface of the lower steel plate has a curved surface so that the thickness of the rubber layer gradually increases from the central portion to the outer peripheral portion ,
An elastic load support, wherein the outer peripheral portion of the curved surface has a smaller radius of curvature than other portions .   2. The elastic load support according to claim 1, wherein the elastic load support is incorporated in a bridge support installed between an upper structure and a lower structure.   The elastic load support according to claim 2, wherein the bearing is a sliding bearing, and a sliding material is provided on an upper portion of the upper steel plate.   The said bearing is a fixed bearing, and the through-hole for inserting the shear key which transmits a horizontal force between upper-lower structures is provided in the center part of the said elastic load support body. Elastic load support.

Images