Bridge bearing and method of setting bearing height in bridge bearing

Abstract

To reduce bending moment due to a horizontal load in a direction perpendicular to a bridge axis, to make a bearing height compact, and to facilitate the execution of replacement work.SOLUTION: A bearing 1 for a bridge includes an upper shoe 2, a lower shoe 3, an elastic support body 4 installed between the upper shoe 2 and the lower shoe 3, and a pair of side blocks 5, 5 installed on the lower shoe 3 and arranged on both sides in the Y direction of the upper shoe 2 in a plan view to regulate displacement of the upper shoe 2 at least in the Y direction. The upper shoe 2 includes a contact portion 10 with which an upper surface of the elastic support body 4 comes into contact, a pair of lower protruding portions 13,13 each protruding toward a corresponding one of the side blocks 5 relative to the contact portion 10 and each having a lower facing surface 14 facing the corresponding one of the side blocks 5, and a pair of upper protruding portions 12 each disposed below a corresponding one of the lower protruding portions 13,13 and each protruding toward a corresponding one of the side blocks 5 relative to the contact portion 10. And a pair of overhanging projecting portions 22,22 each having an overhanging facing surface 23 facing the side block 5, and each overhanging facing surface 23 is connected to the lower side facing surface 14 so as to be flush therewith.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This disclosure relates to a bridge bearing installed to support a bridge, and a method for setting the bearing height, which is the overall height of the bridge bearing. In this disclosure, the horizontal direction along the axial direction of the bridge is referred to as the "bridge axis direction," and the horizontal direction perpendicular to the bridge axis direction is referred to as the "direction perpendicular to the bridge axis." However, the "direction perpendicular to the bridge axis" includes the direction strictly perpendicular to the bridge axis direction, and allows for some degree of error. [Background technology]

[0002] Bridge bearings are interposed between a superstructure installed on the bridge side and a substructure installed on the ground side to support the bridge. As disclosed in Japanese Patent No. 7403106 (Patent Document 1), for example, a bridge bearing is known that includes an upper shoe fixed to the superstructure, a lower shoe fixed to the substructure, a bearing body (elastic support) installed between the upper shoe and the lower shoe, and a pair of side blocks installed on both sides of the upper shoe on the lower shoe in a direction perpendicular to the bridge axis. The elastic support is formed, for example, of laminated rubber and transmits vertical and horizontal loads acting on the superstructure to the substructure. The side blocks engage with the upper shoes from above, restricting displacement of the superstructure in the direction perpendicular to the bridge axis and transmitting the load in the same direction to the substructure, while also suppressing upward lift acting on the superstructure during an earthquake. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7403106 Summary of the Invention [Problem to be solved by the invention]

[0004] The bearing height of bridge bearings is determined by the loads in the direction of the bridge axis and perpendicular to the bridge axis, but if the bearing height is too high and there are restrictions on the space under the bridge girder, replacement work becomes difficult. In particular, the standards required for bridge bearings have become stricter in recent years, and if bearings are designed according to the current standards, the bearing height may end up being higher than the existing bearing. In this case, it is necessary to cut out part of the substructure to make space for the new bearing, which increases costs and labor.

[0005] One of the factors that increases the support height is the bending stress (the value obtained by dividing the bending moment by the section modulus) based on the bending moment generated by the horizontal load perpendicular to the bridge axis. Figure 9 shows a cross section of a portion of a conventional bridge bearing. The Y direction is perpendicular to the bridge axis, and the Z direction is vertical. Bridge bearing 100 includes upper shoe 101 fixed to an upper structure (not shown), lower shoe 102 fixed to a lower structure (not shown), and elastic support 103 installed between upper shoe 101 and lower shoe 102. A pair of side blocks 104 are installed on both ends of lower shoe 102 in the Y direction. Side blocks 104 protrude into notches 105 formed on both ends of upper shoe 101 in the Y direction. A step 106 is formed on the back side of notch 105. A vertical displacement restriction part 107 protruding above step 106 is formed on the upper end of side block 104. The vertical displacement restricting portion 107 interferes with the step portion 106, thereby restricting the displacement of the upper shoe 101 in the Z direction. Protrusions 108 that protrude toward the side blocks 104 are formed below the notches 105 at both ends of the upper shoe 101 in the Y direction. The side blocks 104 face opposing surfaces 109, which are the protruding surfaces of the protrusions 108, and displacement of the upper shoe 101 in the Y direction is restricted.

[0006] In this bridge bearing 100, the horizontal load Fy in the Y direction acting on the upper shoe 101 acts in the Y direction on the side block 104 from the center point in the Z direction of the contact surface with the side block 104, that is, the center point P in the Z direction of the opposing surface 109. In this case, if the distance in the Z direction from the bottom surface of the lower shoe 102 to the position where the horizontal load Fy acts is h, the thickness of the lower shoe 102 is t, and the distance in the Z direction from the top surface of the lower shoe 102 to the position where the horizontal load Fy acts is h0, the bending moment M generated by the horizontal load Fy is expressed by the following equation. M=Fy·(h0+t / 2) Since the thickness of the members, particularly the thickness of the lower shoe 102, is determined to resist the bending stress caused by this bending moment M, it is difficult to make the bearing height compact.

[0007] Therefore, the purpose of this disclosure is to provide a bridge bearing that reduces the bending moment due to horizontal loads perpendicular to the bridge axis, thereby compacting the bearing height and facilitating replacement work, as well as a method for setting the bearing height for a bridge bearing. [Means for solving the problem]

[0008] In order to achieve the above object, a first configuration of the present disclosure is a bridge bearing that supports a bridge, An upper shoe fixed to the superstructure on the bridge side; A lower shoe fixed to the substructure on the ground side; an elastic support member installed between the upper shoe and the lower shoe and configured to transmit vertical and horizontal loads acting between the upper structure and the lower structure; and a pair of side blocks that are installed on the lower shoe and are arranged on both sides of the upper shoe in a direction perpendicular to the bridge axis, which is perpendicular to the horizontal direction of the bridge in a plan view, and that restrict displacement of the upper shoe at least in the direction perpendicular to the bridge axis. And, the upper shoe has: a contact portion with which the upper surface of the elastic support member comes into contact; a pair of first protruding portions each protruding toward one of the side blocks relative to the contact portion and having a first opposing surface opposing the side block; a pair of second protruding portions are provided, each disposed below each of the first protruding portions, protruding toward the side block beyond the abutment portion, and having a second opposing surface opposing the side block; Each of the second opposing surfaces is flush with and connected to the first opposing surface, or is located closer to the side block than the first opposing surface. Another aspect of the first configuration is characterized in that, in the above configuration, each of the second opposing surfaces is connected flush with the first opposing surface, and the vertical thickness of each of the second protrusions is set so that the vertical center point of the combined thickness of the first protrusion and the second protrusion is at the same height as the abutment portion, or so that the center point is lower than the abutment portion. Another aspect of the first configuration is characterized in that, in the above configuration, the vertical thickness of the lower shoe is set according to the following relationship, where b is the thickness when the second protrusion is not present and b' is the thickness when the second protrusion is provided. b×0.5≦b'≦b×0.97 Another aspect of the first configuration is characterized in that, in the above configuration, the area of ​​the lower shoe where the elastic support is provided is a recess that is recessed downward by the thickness b'. Another aspect of the first configuration is characterized in that, in the above configuration, each of the second opposing surfaces is located closer to the side block than the first opposing surfaces. Another aspect of the first configuration is that, in the above configuration, a step portion having a third opposing surface facing the side block at a position farther away from the side block than the first opposing surface in the bridge axis perpendicular direction is formed on the upper side of each of the first protrusions of the upper shoe, Each of the side blocks has a horizontal displacement regulating portion that faces the first protruding portion and the second protruding portion of the upper shoe in the direction perpendicular to the bridge axis, and a vertical displacement regulating portion that is provided above the horizontal displacement regulating portion, protrudes into the step portion, and overlaps the upper side of the first protruding portion, and the horizontal displacement regulating portion has a horizontal displacement regulating surface that faces the first opposing surface and the second opposing surface without contacting them and regulates displacement of the upper shoe in the direction perpendicular to the bridge axis, and the vertical displacement regulating portion has a block-side opposing surface that faces the third opposing surface, The distance between the first opposing surface and the horizontal displacement restriction surface and between the second opposing surface and the horizontal displacement restriction surface is smaller than the distance between the third opposing surface and the block-side opposing surface. Another aspect of the first configuration is characterized in that, in the above configuration, the second protrusion is provided in the upper shoe in a part of the range in the bridge axis direction, which is the horizontal direction along the axial direction of the bridge. In order to achieve the above object, the second configuration of the present disclosure is: An upper shoe fixed to the superstructure on the bridge side; A lower shoe fixed to the substructure on the ground side; an elastic support member installed between the upper shoe and the lower shoe and configured to transmit vertical and horizontal loads acting between the upper structure and the lower structure; A method for setting the bearing height, which is the overall height in the vertical direction, in a bridge bearing that includes a pair of side blocks that are installed on the lower shoe and are arranged on both sides of the upper shoe in a direction perpendicular to the bridge axis, which is perpendicular to the horizontal direction of the bridge in a plan view, and that restrict displacement of the upper shoe at least in the direction perpendicular to the bridge axis. And, on the upper shoe, a contact portion with which the upper surface of the elastic support member comes into contact; a pair of first protruding portions each protruding toward one of the side blocks relative to the contact portion and having a first opposing surface opposing the side block; a pair of second protruding portions disposed below each of the first protruding portions, protruding toward the side block beyond the abutting portion, and having a second opposing surface opposing the side block, Each of the second opposing surfaces is connected to the first opposing surface so as to be flush with the first opposing surface, or is positioned closer to the side block than the first opposing surface, The thickness of the lower shoe when the second protrusion is not provided is defined as b, and the thickness of the lower shoe when the second protrusion is provided is defined as b', and the thickness of the lower shoe is set so that b and b' satisfy the following relationship. b×0.5≦b'≦b×0.97 [Effects of the Invention]

[0009] According to the present disclosure, the provision of a second protrusion makes it possible to reduce the acting height of the horizontal load perpendicular to the bridge axis. This reduces the bending moment due to the horizontal load perpendicular to the bridge axis, allowing for a smaller lower shoe thickness, which in turn leads to a more compact bearing height. This makes it possible to install bridge bearings even when there are restrictions on the space under the girder, and makes replacement work easier. Furthermore, the more compact the bearing height, the lighter the weight can be. According to another aspect of the first configuration, in addition to the above-mentioned effects, the vertical thickness of each second protrusion, whose second opposing surface is connected flush with the first opposing surface, is set so that the vertical midpoint of the combined thickness of the first protrusion and the second protrusion is at the same height as the abutment portion, or so that the midpoint is lower than the abutment portion, so that the acting height of the horizontal load can be effectively lowered by setting the thickness of the second protrusion. According to another aspect of the first configuration, in addition to the above effects, the thickness of the lower shoe is set to satisfy the relationship b×0.5≦b'≦b×0.97, where b is the thickness when the second protrusion is not provided and b' is the thickness when the second protrusion is provided. This allows the thickness of the lower shoe to be set small within a range that ensures the necessary rigidity. According to another aspect of the first configuration, in addition to the above effects, the installation area of ​​the elastic support in the lower shoe is recessed downward by a thickness b', so that the support height can be reduced compared to when there is no recess. According to another aspect of the first configuration, in addition to the above-mentioned effects, since each second opposing surface is located closer to the side block than the first opposing surface, the horizontal load acts on the side block from the center point of the vertical thickness of the second opposing surface that protrudes toward the side block. This further reduces the height at which the horizontal load acts, leading to a further reduction in bending moment. According to another aspect of the first configuration, the distance between the first and second opposing surfaces and the horizontal displacement control surface is smaller than the distance between the third opposing surface and the block side opposing surface, so that the horizontal load caused by the displacement of the upper shoe in the direction perpendicular to the bridge axis can be reliably applied to the horizontal displacement control surface of the side block. According to another aspect of the first configuration, the second protrusion is provided in a part of the range in the bridge axis direction on the upper shoe, so that it is sufficient to form the minimum necessary lower protrusion, and even if a lower protrusion is added, the cost increase can be suppressed. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a plan view of a bridge bearing. [Figure 2] FIG. 2 is a front view of the bridge bearing as seen from the bridge axis direction. [Figure 3] This is a side view of the bridge bearing viewed from a direction perpendicular to the bridge axis. [Figure 4] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 2 is a cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 10 is an explanatory diagram of a state in which a horizontal load acts. [Figure 7] FIG. 10 is a cross-sectional view showing a modified example of a bridge bearing. [Figure 8] FIG. 10 is a partial cross-sectional view showing a modified example of a bridge bearing. [Figure 9] FIG. 10 is a partial cross-sectional view of a conventional bridge bearing. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a plan view showing an example of a bridge bearing, Fig. 2 is a front view of the bridge bearing seen from the bridge axis direction, and Fig. 3 is a side view of the bridge bearing seen from a direction perpendicular to the bridge axis. Fig. 4 is a cross-sectional view taken along line AA in Fig. 1, and Fig. 5 is a cross-sectional view taken along line BB in Fig. 1. In each figure, the X direction is the bridge axis direction, the Y direction is the direction perpendicular to the bridge axis, and the Z direction is the vertical direction. The bridge bearing 1 includes an upper shoe 2, a lower shoe 3, an elastic support 4, and a pair of side blocks 5,5. The upper shoe 2 is a rectangular plate-like body in a plan view, and is made of, for example, steel. The upper shoe 2 is fixed with bolts to an upper structure (for example, a main girder) on the bridge side (not shown). An abutment portion 10 for contacting the elastic support body 4 is formed in the center of the lower surface of the upper shoe 2. At both ends of the upper shoe 2 in the Y direction and in the center in the X direction, a pair of cutouts 11, 11 that are U-shaped in plan view and open outward in the Y direction are formed, located outside the abutment portion 10 in the Y direction.

[0012] A part of a main body portion 31 (described later) of the side block 5 is disposed in each cutout portion 11. A step portion 12 is formed on the inner surface at the back side of each cutout portion 11, with the lower side positioned further outward in the Y direction than the upper side. A lower protrusion portion 13 is formed on the lower side of each step portion 12, protruding further outward in the Y direction than the abutment portion 10 and facing the main body portion 31. The protruding surface of the lower protrusion portion 13 forms a lower opposing surface 14, which is a plane defined by the X direction and the Z direction. The lower protrusion portion 13 is an example of a first protrusion of the present disclosure, and the lower opposing surface 14 is an example of a first opposing surface of the present disclosure. An upper protrusion 15 is formed on the upper side of the step portion 12, protruding outward in the Y direction beyond the contact portion 10 and facing the main body portion 31. The protruding surface of the upper protrusion 15 forms an upper opposing surface 16, which is a plane defined by the X direction and the Z direction. The upper opposing surface 16 is an example of a third opposing surface of the present disclosure.

[0013] Lower overhangs 20, 20 are provided on the underside of the upper shoe 2 at both ends in the Y direction. Each lower overhang 20 is strip-shaped extending in the X direction and is located outward in the Y direction from the abutting portion 10. The end face extending in the X direction and both end faces extending in the Y direction of each lower overhang 20 are flush with and connected to the corresponding end faces of the upper shoe 2. Directly below each notch 11, each lower overhang 20 has a lower notch 21 that is slightly smaller in width than the notch 11 in the Y direction and opens outward with a depth that matches the lower protrusion 13. Therefore, directly below the lower protrusion 13, an overhanging protrusion 22 is formed that protrudes outward in the Y direction from the abutting portion 10 and faces the main body 31. The protruding surface of the overhanging protrusion 22 is a plane defined by the X and Z directions, forming an overhanging opposing surface 23 that is flush with the lower opposing surface 14. The thickness of each overhanging protrusion 22 in the Z direction is greater than the thickness of the lower protrusion 13. The overhanging protrusion 22 is an example of a second protrusion of the present disclosure, and the overhang opposing surface 23 is an example of a second opposing surface of the present disclosure. The lower protrusion 20 may be formed integrally with the upper shoe 2 by cutting or the like, or may be formed by attaching a separate member to the lower surface of the upper shoe 2 with bolts or the like.

[0014] The lower shoe 3 is a rectangular plate-like body in plan view that is slightly larger than the upper shoe 2 and is made of, for example, steel. The lower shoe 3 is fixed to a substructure (for example, a bridge pier) (not shown) on the ground side with anchor bolts. The elastic support 4 is a square plate-like body in a plan view, and is a laminated type made by alternately stacking rubber plates and steel plates in the Z direction, for example. The elastic support 4 is installed in the center between the upper shoe 2 and the lower shoe 3, and its lower part is fixed to the upper surface of the lower shoe 3 with a bolt (not shown). The upper surface of the elastic support 4 abuts against the abutment part 10 of the upper shoe 2.

[0015] The side blocks 5, 5 are arranged on both sides of the upper shoe 2 in the Y direction in plan view and are fixed onto the lower shoe 3. Each side block 5 includes a base portion 30 and a main body portion 31 and is made of, for example, steel. Each base portion 30 is in the shape of a strip extending along the edge of the lower shoe 3 in the X direction and is fixed to the lower shoe 3 with multiple bolts. In plan view, the base portions 30, 30 are located outside the upper shoe 2 in the Y direction. Each main body 31 is provided at the center of the base 30 in the X direction. The main body 31 has a rectangular shape in a plan view and protrudes upward from the base 30. The top surface of the main body 31 is lower than the top surface of the upper shoe 2.

[0016] Each main body portion 31 has a horizontal displacement regulating portion 32 and a vertical displacement regulating portion 33. The horizontal displacement regulating portion 32 is formed larger than the base portion 30 in the Y direction and protrudes into the cutout portion 11. The protruding surface of the horizontal displacement regulating portion 32 is a horizontal displacement regulating surface 34 that is a plane defined by the X direction and the Z direction. As shown in FIG. 6 , the horizontal displacement regulating surface 34 faces the lower opposing surface 14 of the lower protruding portion 13 of the upper shoe 2 and the protruding opposing surface 23 of the protruding protruding portion 22 at a distance S1 in the Y direction. The vertical displacement restricting portion 33 is formed above the horizontal displacement restricting portion 32 and protrudes further toward the upper shoe 2 than the horizontal displacement restricting portion 32. The vertical displacement restricting portion 33 protrudes into the step portion 12 of the notch 11 above the lower protruding portion 13 of the upper shoe 2, overlapping the lower protruding portion 13 without contacting it, and has a vertical displacement restricting surface 35 on its underside, which is a plane defined by the X and Y directions. The surface of the vertical displacement restricting portion 33 protruding into the step portion 12 is a block-side opposing surface 36, which is a plane defined by the X and Z directions. The block-side opposing surface 36 faces the upper opposing surface 16 in the step portion 12 with a distance S2 in the Y direction. The distance S1 between the lower opposing surface 14 and the protruding opposing surface 23 and the horizontal displacement restricting surface 34 is smaller than the distance S2 between the upper opposing surface 16 and the block-side opposing surface 36.

[0017] The bridge bearing 1 configured as described above, when installed between the superstructure and the substructure, transmits the vertical load in the Z direction acting from the superstructure to the substructure. It also transmits the horizontal loads in the X and Y directions acting from the superstructure due to earthquakes, wind, etc. to the substructure. In particular, when a horizontal load in the Y direction acts on the upper structure and the upper shoe 2 displaces relative to the elastic support 4 at the abutment portion 10, the lower opposing surface 14 and the protruding opposing surface 23, which face the horizontal displacement regulating surface 34 at a distance S1 that is smaller than the distance S2, come into contact with the horizontal displacement regulating surface 34 first. At this time, the horizontal load Fy in the Y direction acting on the upper shoe 2 acts on the horizontal displacement restriction surface 34 of the side block 5 from the center point P in the Z direction of the combined thickness of the lower protrusion 13 and the overhanging protrusion 22, as shown in Figure 6. This acting height h0' (the distance in the Z direction from the upper surface of the lower shoe 3 to the center point P) is located below the abutment portion 10, and is therefore smaller than the acting height h0 of the horizontal load Fy shown in Figure 9. For this reason, the bending moment M' determined by M' = Fy · (h0' + t / 2) is reduced compared to the bending moment M in Figure 9. By reducing the bending moment M' in this way, it is possible to make the thickness of the lower shoe 3 smaller than that shown in Fig. 9. In other words, less rigidity is required to resist the reduced bending moment M', and therefore the lower shoe 3 can be made smaller accordingly.

[0018] In this case, the thickness of the lower shoe 3 in the Z direction can be set, for example, according to the following relationship (1), where b is the thickness when there is no protruding portion 22 and b' is the thickness when there is a protruding portion 22. b × 0.5 ≦ b' ≦ b × 0.97 (1) By setting these conditions, it is possible to obtain a lower shoe 3 having a thickness that is balanced between ensuring the necessary rigidity and reducing the thickness.

[0019] The bridge bearing 1 of the above form includes an upper shoe 2 fixed to the superstructure on the bridge side, a lower shoe 3 fixed to the substructure on the ground side, an elastic support 4 installed between the upper shoe 2 and the lower shoe 3 and transmitting vertical and horizontal loads acting between the upper structure and the substructure, and a pair of side blocks 5, 5 installed on the lower shoe 3 and positioned on both sides of the upper shoe 2 in the Y direction in a plan view, and restricting displacement of the upper shoe 2 at least in the Y direction. The upper shoe 2 is provided with a contact portion 10 against which the upper surface of the elastic support 4 abuts, a pair of lower protrusions 13, 13 that protrude further toward each side block 5 than the contact portion 10 and have lower opposing surfaces 14 facing the side blocks 5, and a pair of protruding protrusions 22, 22 that are arranged below each lower protrusion 13, 13, protrude further toward the side blocks 5 than the contact portion 10, and have protruding opposing surfaces 23 facing the side blocks 5, and each protruding opposing surface 23 is connected flush with the lower opposing surface 14.

[0020] According to this configuration, the provision of the overhanging protrusion 22 makes it possible to reduce the acting height of the horizontal load Fy in the Y direction. As a result, the bending moment M' due to the horizontal load Fy in the Y direction is reduced, which allows the thickness of the lower shoe 3 to be reduced, which in turn leads to a more compact bearing height. Therefore, even in cases where there are restrictions on the space under the girder, the bridge bearing 1 can be installed, and replacement work can be carried out easily. Furthermore, the more compact the bearing height, the lighter the weight can be.

[0021] Each protruding opposing surface 23 is flush with and connected to the lower opposing surface 14, and the Z-direction thickness of each protruding portion 22 is set so that the Z-direction center point P of the combined thickness of the lower protruding portion 13 and the protruding portion 22 is lower than the abutment portion 10. Therefore, by setting the thickness of the overhanging protrusion 22, the acting height of the horizontal load Fy can be effectively reduced. The thickness of the lower shoe 3 in the Z direction is set according to the relationship (1) above, where the thickness when there is no overhanging protrusion 22 is b and the thickness when there is an overhanging protrusion 22 is b'. Therefore, the thickness of the lower shoe 3 can be set small within a range that ensures the necessary rigidity.

[0022] A step portion 12 having an upper opposing surface 16 facing the side block 5 is formed on the upper side of each lower protrusion 13 of the upper shoe 2 at a position farther away from the side block 5 in the Y direction than the lower opposing surface 14. Each side block 5 has a horizontal displacement regulating portion 32 that faces the lower protrusion 13 and the overhanging protrusion 22 of the upper shoe 2 in the Y direction, and a vertical displacement regulating portion 33 that is provided above the horizontal displacement regulating portion 32, protrudes into the step portion 12, and overlaps the upper side of the lower protrusion 13.The horizontal displacement regulating portion 32 is provided with a horizontal displacement regulating surface 34 that faces the lower opposing surface 14 and the overhanging opposing surface 23 without contacting them, and regulates displacement of the upper shoe 2 in the Y direction, and the vertical displacement regulating portion 33 is provided with a block side opposing surface 36 that faces the upper opposing surface 16. A distance S1 between the lower opposing surface 14 and the protruding opposing surface 23 and the horizontal displacement restriction surface 34 is smaller than a distance S2 between the upper opposing surface 16 and the block-side opposing surface 36. Therefore, the horizontal load Fy caused by the displacement of the upper shoe 2 in the Y direction can be reliably applied to the horizontal displacement restriction surface 34 of the side block 5. The overhanging protrusion 22 is provided in a lower cutout 21 that is part of the range in the X direction in the upper shoe 2. Therefore, it is sufficient to form the minimum number of overhanging protrusions 22 necessary, and even if the overhanging protrusions 22 are added, an increase in cost can be suppressed.

[0023] The method of setting the bearing height in the bridge bearing 1 of the above embodiment is to provide the upper shoe 2 with a contact portion 10 against which the upper surface of the elastic support 4 abuts, a pair of lower protruding portions 13, 13 that protrude further toward each side block 5 than the contact portion 10 and have lower opposing surfaces 14 that face the side blocks 5, and a pair of overhanging protruding portions 22, 22 that are respectively disposed below each lower protruding portion 13 and protrude further toward the side blocks 5 than the contact portion 10 and have overhanging opposing surfaces 23 that face the side blocks 5, and connect the overhanging opposing surfaces 23 flush with the lower opposing surfaces 14, while The thickness of the lower shoe 3 when there is no overhanging protrusion 22 is defined as b, and the thickness of the lower shoe 3 when there is an overhanging protrusion 22 is defined as b'. The thickness of the lower shoe 3 is set so that b and b' satisfy the relationship (1) above.

[0024] Even in this configuration, the height at which the horizontal load Fy in the Y direction acts can be reduced by providing the overhanging protrusion 22. Therefore, the bending moment M' due to the horizontal load Fy in the Y direction can be reduced, and the thickness of the lower shoe 3 can be reduced to make the bearing height more compact. Therefore, even in cases where there are restrictions on the space under the girder, the bridge bearing 1 can be installed, and replacement work can be carried out easily. Furthermore, the reduction in bearing height also makes it possible to achieve weight reduction.

[0025] Modifications of the present disclosure will be described below. In the bridge bearing 1A shown in FIG. 7, the area on the top surface of the lower shoe 3 where the elastic support 4 is installed is formed as a recess 40 that is recessed downward by a thickness b' set in accordance with the relationship (1) above. In addition, in this bridge support 1A, the Z-direction thickness of the protruding portion 22 is made equal to that of the lower protruding portion 13, and the midpoint P of the thickness between the lower protruding portion 13 and the protruding portion 22 is made to coincide with the height of the abutment portion 10. In this modified example, by forming the installation area of ​​the elastic support 4 as a recess 40 that is recessed downward by a thickness b', the lower surface position of the lower shoe 3 can be made higher compared to when there is no recess 40, thereby making it possible to reduce the thickness. Also, because the recess 40 is provided only in the installation area of ​​the elastic support 4, the lower shoe 3 can be made thicker around the elastic support 4 to ensure the necessary rigidity. Furthermore, the acting height h0' of the horizontal load Fy can be made lower than the acting height h0 in FIG. 9, which leads to a reduction in the bending moment M'.

[0026] In the bridge bearing 1B shown in FIG. 8, the overhang-facing surface 23 of the overhanging projection 22 is positioned closer to the side block 5 than the lower-side facing surface 14 of the lower projection 13. As in this modified example, if each protruding opposing surface 23 is positioned closer to the side block 5 than the lower opposing surface 14, the horizontal load Fy in the Y direction acts on the side block 5 from the center point P of the thickness in the Z direction of the protruding opposing surface 23 that protrudes toward the side block 5. Therefore, the acting height h0' of the horizontal load Fy can be made even lower than in the cases of Figures 6 and 7, leading to a further reduction in the bending moment M'.

[0027] In the above-described embodiment and modified example, a gap is provided between the lower opposing surface of the lower protrusion and the overhang opposing surface of the overhang protrusion and the horizontal displacement regulating surface of the side block, or between the lower opposing surface and the horizontal displacement regulating surface, but this gap does not have to be provided. That is, the lower opposing surface and the overhang opposing surface may be in contact with the horizontal displacement regulating surface, or the lower opposing surface and the horizontal displacement regulating surface may be in contact with each other. In the above-described embodiments and modified examples, the center point of the combined thickness of the lower protrusion and the overhanging protrusion is set to be at the same height as the abutment portion or lower than the abutment portion, but if the thickness of the lower shoe can be reduced by reducing the bending moment, the center point may be higher than the abutment portion. In the above-described embodiment and modified example, the overhanging protrusion is provided in a part of the range of the upper shoe in the X direction, but the overhanging protrusion may be provided over the entire range of the upper shoe in the X direction. The recesses provided in the lower shoe shown in FIG. 7 are not limited to being provided only in the installation area of ​​the elastic support body, but may be provided over the entire lower shoe beyond the installation area. The step portion of the upper shoe and the vertical displacement restricting portion of the side block may be omitted, that is, the side block may be provided with only the horizontal displacement restricting portion of the upper shoe. The elastic support may be a disc type in which a disc steel plate is insert-molded into urethane rubber, for example. [Explanation of symbols]

[0028] 1, 1A, 1B... bridge bearing, 2... upper shoe, 3... lower shoe, 4... elastic support, 5... side block, 10... abutment portion, 11... notch portion, 12... step portion, 13... lower protruding portion, 14... lower opposing surface, 15... upper protruding portion, 16... upper opposing surface, 20... lower protruding portion, 21... lower notch portion, 22... protruding portion, 23... protruding opposing surface, 30... base portion, 31... main body portion, 32... horizontal displacement restriction portion, 33... vertical displacement restriction portion, 34... horizontal displacement restriction surface, 35... vertical displacement restriction surface, 36... block side opposing surface.

Claims

1. A bridge bearing that supports a bridge, An upper shoe fixed to the superstructure on the bridge side; A lower shoe fixed to the substructure on the ground side; an elastic support member installed between the upper shoe and the lower shoe and configured to transmit vertical and horizontal loads acting between the upper structure and the lower structure; a pair of side blocks that are installed on the lower shoe and are arranged on both sides of the upper shoe in a direction perpendicular to the bridge axis that is perpendicular to the horizontal direction of the bridge in a plan view, and that restrict displacement of the upper shoe at least in the direction perpendicular to the bridge axis; The upper shoe has: a contact portion with which the upper surface of the elastic support member comes into contact; a pair of first protruding portions each protruding toward one of the side blocks relative to the contact portion and having a first opposing surface opposing the side block; a pair of second protruding portions are provided, each disposed below each of the first protruding portions, protruding toward the side block beyond the abutment portion, and having a second opposing surface opposing the side block; Each of the second opposing surfaces is flush with and connected to the first opposing surfaces, or is located closer to the side block than the first opposing surfaces.

2. 2. The bridge bearing according to claim 1, wherein each of the second opposing surfaces is flush with and connected to the first opposing surface, and the vertical thickness of each of the second protruding portions is set so that the vertical center point of the combined thickness of the first protruding portion and the second protruding portion is at the same height as the abutting portion, or so that the center point is lower than the abutting portion.

3. The bridge bearing according to claim 1, wherein the vertical thickness of the lower shoe is set according to the following relationship, where b is the thickness when the second protrusion is not present and b' is the thickness when the second protrusion is provided. b×0.5≦b′≦b×0.97

4. 4. The bridge bearing according to claim 3, wherein the area of ​​the lower shoe where the elastic support is installed is a recess that is recessed downward by the thickness b'.

5. The bridge bearing according to claim 1 , wherein each of the second opposing surfaces is located closer to the side block than the first opposing surfaces.

6. A step portion having a third opposing surface facing the side block is formed on the upper side of each of the first protrusions of the upper shoe at a position farther from the side block than the first opposing surface in the direction perpendicular to the bridge axis, Each of the side blocks has a horizontal displacement regulating portion that faces the first protruding portion and the second protruding portion of the upper shoe in the direction perpendicular to the bridge axis, and a vertical displacement regulating portion that is provided above the horizontal displacement regulating portion, protrudes into the step portion, and overlaps the upper side of the first protruding portion, and the horizontal displacement regulating portion has a horizontal displacement regulating surface that faces the first opposing surface and the second opposing surface without contacting them and regulates displacement of the upper shoe in the direction perpendicular to the bridge axis, and the vertical displacement regulating portion has a block-side opposing surface that faces the third opposing surface, 2. The bridge bearing according to claim 1, wherein the distance between the first opposing surface and the horizontal displacement restriction surface and the second opposing surface is smaller than the distance between the third opposing surface and the block-side opposing surface.

7. The bridge bearing according to claim 1 , wherein the second protrusion is provided in the upper shoe in a part of a range in the bridge axis direction, which is a horizontal direction along the axis of the bridge.

8. An upper shoe fixed to the superstructure on the bridge side; A lower shoe fixed to the substructure on the ground side; an elastic support member installed between the upper shoe and the lower shoe and configured to transmit vertical and horizontal loads acting between the upper structure and the lower structure; a pair of side blocks that are installed on the lower shoe and arranged on both sides of the upper shoe in a direction perpendicular to the bridge axis that is orthogonal to the horizontal direction of the bridge in a plan view, and that restrict displacement of the upper shoe at least in the direction perpendicular to the bridge axis, and a method for setting a bearing height that is an overall height in the vertical direction in a bridge bearing that includes: On the upper shoe, a contact portion with which the upper surface of the elastic support member comes into contact; a pair of first protruding portions each protruding toward one of the side blocks relative to the contact portion and having a first opposing surface opposing the side block; a pair of second protruding portions disposed below each of the first protruding portions, protruding toward the side block beyond the abutting portion, and having a second opposing surface opposing the side block, Each of the second opposing surfaces is connected to the first opposing surface so as to be flush with the first opposing surface, or is positioned closer to the side block than the first opposing surface; A method for setting the bearing height in a bridge bearing, in which the thickness of the lower shoe when the second protrusion is not present is b, and the thickness of the lower shoe when the second protrusion is provided is b', and the thickness of the lower shoe is set so that b and b' satisfy the following relationship. b×0.5≦b′≦b×0.97

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