Displacement control structure for bridge girders

Abstract

To provide a displacement control structure of a bridge girder, which can control the displacement of the bridge girder in a direction orthogonal to a bridge axis, and which can be applied to a bridge in which only a narrow space can be secured around a bearing part.SOLUTION: This displacement control structure of a bridge girder controls the displacement of the bridge girder in an earthquake. This device is provided with a side surface support member 3 for bringing an end part 33 into contact with a side surface in a direction R1 orthogonal to a bridge axis of a bridge girder 1, a pedestal part 4 arranged adjacently in the direction orthogonal to the bridge axis of a bearing part 2 of the bridge girder and fixed to a pier M, and a bolt joining part 5 for joining a lower part of the side surface support member on the pedestal part with a bolt. In the bolt joining part, when a force applied from the bridge girder to the side surface support member exceeds a predetermined value, slippage will occur, and the side surface support member will move.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a displacement control structure for a bridge girder that controls the displacement of the bridge girder during an earthquake. [Background technology]

[0002] Bridge supports are generally designed to prevent damage during earthquakes. However, when taking seismic measures for existing bridges, if the bearings are reinforced or replaced to improve their strength, the inertial force acting on the bridge piers increases, which can lead to damage to the piers.

[0003] On the other hand, if damage to the supports is allowed, the displacement of the bridge girder after the support damage will be large, and if the bridge girder deviates from the support, a step will appear on the track surface of the railway bridge, significantly reducing the safety of running traffic and requiring time and effort to restore after an earthquake.

[0004] On the other hand, a structure is known that provides vibration control by using friction dampers to generate a damping force due to friction when there is relative movement during an earthquake, in response to displacement that occurs in the bridge girder's axis direction (see Patent Document 1).

[0005] Furthermore, as disclosed in Patent Document 2, a seismic isolation structure for a bridge is known that prevents displacement in a direction perpendicular to the bridge axis during a major earthquake by interposing lead dampers fixed to the piers between bridge girders that are supported at intervals in a direction perpendicular to the bridge axis.

[0006] Furthermore, a step prevention device is known that is installed adjacent to a support part to keep the bridge girder supported by the support part supported at the same height when a major earthquake occurs and the bridge girder comes off the support part (see Patent Document 3). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2016-180432 A [Patent Document 2] JP 2002-180418 A [Patent Document 3] JP 2019-124003 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, the step prevention device cannot suppress the displacement of the bridge girder, and furthermore cannot control the behavior of the bridge girder after the bearing is destroyed. In addition, the lead dampers and oil dampers that are placed between the bridge girders as disclosed in Patent Document 2 tend to be large, and may not be able to be placed around the narrow bearing parts.

[0009] Therefore, the present invention aims to provide a bridge girder displacement control structure that can control the displacement of the bridge girder in a direction perpendicular to the bridge axis and can also be applied to bridges where only narrow space can be secured around the support parts. [Means for solving the problem]

[0010] In order to achieve the above-mentioned objective, the bridge girder displacement control structure of the present invention is a bridge girder displacement control structure that controls the displacement of a bridge girder during an earthquake, and comprises a side support member whose end comes into contact with the side surface of the bridge girder in the direction perpendicular to the bridge axis, a base portion that is arranged adjacent to the support portion of the bridge girder in the direction perpendicular to the bridge axis and fixed to a pier or abutment, and a bolt joint portion that bolts the lower part of the side support member onto the base portion, and is characterized in that at the bolt joint portion, when the force acting from the bridge girder to the side support member exceeds a predetermined value, slippage occurs and the side support member moves.

[0011] Here, it is preferable that the surface of the base portion that is exposed after the movement of the side support member is formed at substantially the same height as the support surface of the support portion on which the bridge girder is placed. Also, it is preferable that the surface that is exposed after the movement of the side support member formed on the base portion protrudes toward the support portion.

[0012] Furthermore, the bolt joint may include a friction adjustment plate interposed between the base and the side support member. The friction adjustment plate may be configured to have a long groove through which the bolt is inserted and one end of which is open. The friction adjustment plate may also be configured to have an insertion hole through which the bolt is inserted and has a diameter larger than that of the bolt shaft.

[0013] Furthermore, the end of the side support member may be formed in a shape that allows the side support member to move in accordance with the displacement of the bridge girder in the bridge axis direction, and the bolt joint may be configured to cause slip in the bridge axis direction or in a direction perpendicular to the bridge axis depending on the direction of force acting from the bridge girder to the side support member. Also, the end of the side support member may be configured to be formed of a friction surface material. Effect of the Invention

[0014] The bridge girder displacement control structure of the present invention configured in this way has a side support member whose end is in contact with the side surface of the bridge girder in the direction perpendicular to the bridge axis, and which is bolted onto a base portion fixed to a bridge pier, etc. This side support member will slip and move if the force acting from the bridge girder exceeds a predetermined value.

[0015] Therefore, depending on the scale of the earthquake, it is possible to control the displacement of the bridge girder in the direction perpendicular to the bridge axis by preventing the displacement of the bridge girder or suppressing the displacement through sliding with frictional resistance. Furthermore, even if only a narrow space can be secured around the support, a displacement control structure can be installed as long as there is space to install the base.

[0016] Furthermore, if the base portion is formed so that the surface exposed after the side support member is moved is approximately the same height as the support surface of the bearing part on which the bridge girder is placed, it is possible to prevent steps from occurring on the track surface, etc. after the bridge girder is moved, in the same way as the step prevention device.

[0017] Furthermore, if the surface exposed after the movement of the side support member formed on the base portion is extended toward the support portion, the weight of the bridge girder will act on the base portion at an early stage, such as at the beginning of the bridge girder's movement, and this can be used as a reaction force to the pull-out force generated on the base portion.

[0018] Furthermore, if the bolt joint where the lower part of the side support member is bolted onto the base is configured with a friction adjustment plate, it becomes easy to adjust the specified value of the acting force at which slippage begins and the magnitude of the friction force during movement of the bridge girder.

[0019] Furthermore, if one end of the long groove through which the bolt of the friction adjustment plate is inserted is open, even if the side support member moves significantly, it is possible to prevent the occurrence of an incident in which the pier that secures the base is damaged.

[0020] Furthermore, if the insertion hole through which the bolt of the friction adjustment plate is inserted is formed larger than the shaft of the bolt, the side support member can be moved in any direction, not just in the direction perpendicular to the bridge axis.

[0021] Furthermore, by configuring the side support members and bolt joints to be able to displace in the bridge axis direction and in a direction perpendicular to the bridge axis, it becomes possible to control not only the displacement in the direction perpendicular to the bridge axis, but also the displacement in the bridge axis direction.

[0022] In addition, by forming the ends of the side support members from friction surface material, a damping force can also be generated by slippage accompanied by friction that occurs between the bridge girder and the friction surface material when the bridge girder is displaced in the bridge axis direction. [Brief description of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram showing an overview of a displacement control structure for a bridge girder according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 13 is an explanatory diagram showing the state in which the bridge girder has been moved onto the base. [Diagram 3] This is an explanatory diagram showing the state in which the bridge girder has fallen from its base. [Figure 4] FIG. 1 is an explanatory diagram illustrating a displacement-controlled structure of a bridge girder restored after a large-scale earthquake. [Diagram 5] FIG. 2 is an explanatory diagram showing the configuration of the displacement control structure of the bridge girder of the first embodiment. [Figure 6] FIG. 2 is a perspective view illustrating the configuration of a side support member and a friction adjustment plate according to the first embodiment. [Figure 7] FIG. 11 is an explanatory diagram showing the configuration of a displacement control structure for a bridge girder in accordance with a second embodiment. [Figure 8] FIG. 11 is an explanatory diagram showing the configuration of a displacement control structure for a bridge girder according to a third embodiment. [Figure 9] FIG. 11 is an explanatory diagram showing the configuration of a displacement control structure for a bridge girder according to a fourth embodiment. [Figure 10] FIG. 13 is an explanatory diagram showing the configuration of a displacement control structure for a bridge girder in accordance with a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an explanatory diagram showing an outline of a displacement control structure for a bridge girder according to the present embodiment.

[0025] The bridge girder displacement control structure of this embodiment is provided for a bridge girder 1 extending in the bridge axis direction supported on a support surface 21 of a bridge bearing 2. The bearing 2 is provided on the upper surface of a pier M or abutment of the bridge constructed from reinforced concrete or the like. The following description takes the bearing 2 provided on the upper surface of the pier M as an example.

[0026] On both side edges of the support part 2 in the direction R1 perpendicular to the bridge axis, block-shaped side blocks 22 protruding above the support surface 21 are provided. Normally, the movement of the bridge girder 1 placed on the support surface 21 in the direction R1 perpendicular to the bridge axis is restricted by the side blocks 22.

[0027] In this embodiment, a steel bridge girder 1 will be described as an example, which includes a bottom flange 11 forming the underside, a web 12 perpendicular to the bottom flange 11, and end stiffeners 13 provided at intervals in the bridge axis direction on both sides of the web 12. Note that the configuration of the bridge girder to which the displacement control structure of the bridge girder of this embodiment can be applied is not limited to this steel bridge girder 1.

[0028] Then, for such bridge girder 1, a bridge girder displacement control structure is provided to control the displacement of the bridge girder 1 during an earthquake. The bridge girder displacement control structure of this embodiment includes a side support member 3 whose end portion 33 comes into contact with the side surface of the bridge girder 1 in the direction orthogonal to the bridge axis R1, a base portion 4 disposed adjacent to the bearing portion 2 in the direction orthogonal to the bridge axis R1, and a bolt joint portion 5 which bolts the lower portion of the side support member 3 to an upper surface 41 of the base portion 4.

[0029] The pedestal 4 is made of steel or casting, placed on the upper surface of the pier M, and fixed to the pier M by a fixed anchor 42. If there is little space on the upper surface of the pier M, the bottom of the pedestal 4 can be made small and the upper part can be made wider. In other words, it is preferable to make the upper part of the pedestal 4 protrude toward the support 2, and to make the distance between the support surface 21 of the support 2 and the upper surface 41 of the pedestal 4 as small as possible.

[0030] The side support member 3, which is attached to the base portion 4 via a bolt joint 5, has a main body portion 31 placed on the base portion 4, an arm portion 32 extending from the main body portion 31 toward the side of the bridge girder 1, and an end portion 33 formed at the tip of the arm portion 32.

[0031] On the other hand, the bolted joint 5 joins the base 4 and the side support member 3 by the fastening force of the bolt 51. In this bolted joint 5, when the force acting on the side support member 3 from the bridge girder 1 exceeds a predetermined value, slippage occurs, and the side support member 3 moves in the direction R1 perpendicular to the bridge axis.

[0032] The displacement control structure of the bridge girder in this embodiment has a target function that changes depending on the magnitude (scale) of the earthquake. (I) In the case of medium-sized earthquakes In the event of an earthquake up to medium size, slippage is not caused at the bolt joints 5, and the end parts 33 of the side support members 3 that are in contact with the sides of the bridge girder 1, such as the end stiffeners 13, serve as restraints, thereby preventing the bridge girder 1 from shifting and damage to the side blocks 22 of the bearing parts 2.

[0033] That is, in the case of an earthquake smaller than medium scale, as shown on the left side of Figure 1, the bridge girder 1 does not displace in the direction R1 perpendicular to the bridge axis, and the state in which the movement is restricted by the end 33 of the side support member 3 is maintained. In short, in the case of an earthquake smaller than medium scale, the displacement of the bridge girder 1 in the direction R1 perpendicular to the bridge axis is prevented by providing the bridge girder displacement control structure of this embodiment.

[0034] (II) In the case of medium to large earthquakes In the event of a medium to large earthquake, slippage of the bolted joints 5 is utilized, and the frictional force of the bolted joints 5 limits the horizontal force that can be withstood, while suppressing girder slippage. When movement in the direction perpendicular to the bridge axis R1 due to slippage of the bridge girder 1 exceeds a certain level, the surface exposed above the base 4 functions as a step prevention work, and the frictional resistance between the bridge girder 1 and the step prevention work controls girder slippage.

[0035] In other words, when a medium- or larger-scale earthquake occurs, the side block 22 of the support 2 is damaged, causing the bridge girder 1 to move significantly in the direction R1 perpendicular to the bridge axis, as shown on the right side of Figure 1. When slippage occurs in the bridge girder 1 due to seismic force, the bearing 2 forms a slip surface 111 between the underside of the lower flange 11 of the bridge girder 1 and the support surface 21, and the energy of the seismic force can be absorbed by the frictional resistance when the weight of the bridge girder 1 is applied. Meanwhile, slippage also occurs in the bolt joint 5 between the base 4 and the side support member 3 with the bolt fastening force still acting, and the energy of the seismic force is absorbed.

[0036] In short, if the bridge girder displacement control structure of this embodiment is installed, when a medium- to large-scale earthquake occurs, the energy due to the seismic force can be effectively absorbed and the displacement of the bridge girder 1 in the direction R1 perpendicular to the bridge axis can be controlled. The amount of energy absorbed by this slippage can be adjusted by adjusting the friction coefficient of the sliding surface of the bolt joint 5 or the bolt fastening force.

[0037] The friction coefficient of the sliding surface of the bolt joint 5 can be adjusted directly on the upper surface 41 of the base 4 or the lower surface of the side support member 3, but it can also be adjusted by using a friction adjustment plate as described below. The friction coefficient of the sliding surface can be adjusted within a range of about 0.1 to 0.6 depending on the state of the finished surface, such as a fluororesin (PTFE) plate, stainless steel plate, rough surface, inorganic zinc-rich paint, red rust state, etc. Furthermore, by making the sliding surface uneven, it is possible to generate even greater frictional resistance.

[0038] On the other hand, the magnitude of the fastening force of the bolts can be adjusted by the bolt axial force and the number of bolts 51 to be installed.

[0039] (III) In the case of a large earthquake or larger In the event of a large-scale earthquake, factors such as frictional resistance between the bridge girder 1 and pier M are taken into consideration to prevent the bridge from collapsing, in which case the bridge girder 1 will fall off the top of pier M.

[0040] 2 shows a state in which the side support member 3 has come off the base 4, and most of the bridge girder 1 has moved onto the friction adjustment plate 52 provided on the base 4. Once the side support member 3 has come off, energy absorption by slippage at the bolt joint 5 cannot be expected, but the energy of the seismic force can be absorbed by the frictional force generated between the friction adjustment plate 52 and the underside of the bridge girder 1. Even if a large-scale earthquake occurs, it is desirable that the bridge girder 1 that has fallen from the base 4 remain on the top surface of the pier M as shown in FIG. 3, preventing the bridge from collapsing.

[0041] Fig. 4 is an explanatory diagram showing an example of a displacement control structure for a bridge girder restored after a large-scale earthquake. Even if a large-scale earthquake occurs and the side block 22 of the support part 2 is damaged, the bridge girder 1 can be returned to the support surface 21 of the support part 2, and then a new beam-shaped side support member 3A can be installed, allowing for rapid restoration.

[0042] Generally, if the side block 22 is damaged, the support part 2 needs to be replaced. However, with the bridge girder displacement control structure of this embodiment, the existing support part 2 and the remaining base part 4 are utilized, and the side support member 3A is installed on the base part 4 and joined to the base part 4 with bolts 51 to form the bolt joint part 5A, making it possible to easily restore the structure.

[0043] In short, even if the side block 22 of the support part 2 is damaged and disappears, the end 33 of the side support member 3A can be brought into contact with the side of the bridge girder 1, thereby making it possible to function as a resistance member against horizontal forces similar to the side block 22.

[0044] Next, the operation of the displacement control structure for a bridge girder according to this embodiment will be described. The bridge girder displacement control structure of this embodiment configured in this manner has an end portion 33 in contact with the side surface of the bridge girder 1 in the direction R1 perpendicular to the bridge axis, and is equipped with a side support member 3 that is bolted to the upper surface 41 of a base portion 4 that is fixed to a pier M or the like. This side support member 3 will slip and move when the force acting from the bridge girder 1 exceeds a predetermined value.

[0045] Therefore, depending on the scale of the earthquake, it is possible to control the displacement of the bridge girder 1 in the direction R1 perpendicular to the bridge axis by preventing the displacement of the bridge girder 1 or suppressing the displacement by slippage with frictional resistance. In other words, it is possible to reduce the horizontal force generated by an earthquake by utilizing slippage.

[0046] Furthermore, even if only a narrow space can be secured around the support part 2, a displacement control structure can be provided as long as there is space to install the pedestal part 4. In other words, the pedestal part 4 can be designed to match the size of the space in which it is installed, making it possible to make it compact.

[0047] Furthermore, if the upper part of the pedestal part 4 is formed so that the surface exposed after the side support member 3 moves is at approximately the same height as the support surface 21 of the bearing part 2 on which the bridge girder 1 rests, it is possible to prevent steps from occurring on the track surface laid on the bridge after the bridge girder 1 moves, just like the step prevention device. Here, the surface exposed after the side support member 3 moves can be the upper surface 41 of the pedestal part 4, or the upper surface of the friction adjustment plate 52.

[0048] Furthermore, if the surface exposed after the movement of the side support member 3 formed on the base portion 4 is extended toward the support portion 2, the weight of the bridge girder 1 will act on the base portion 4 at an early stage, such as at the beginning of the movement of the bridge girder 1, and this can be utilized as a reaction force to the pull-out force generated in the base portion 4.

[0049] That is, in the state shown on the right side of Fig. 1, the sliding of the side support member 3 pressed by the bridge girder 1 causes a force to act on the fixed anchor 42 securing the pedestal 4 to be pulled out upward. If this force becomes too large, the fixed anchor 42 will be pulled out, causing damage to the pier M. In contrast, when the bridge girder 1 moves onto the pedestal 4, the force pushing down on the pedestal 4 acts due to the weight of the bridge girder 1 and is offset by the pull-out force, reducing the load on the fixed anchor 42 and preventing damage (see Fig. 5).

[0050] Furthermore, if the bolt joint 5 that bolts the upper surface 41 of the base 4 to the lower part of the side support member 3 is configured with a friction adjustment plate 52, it becomes easy to adjust the specified value of the acting force at which slippage begins and the magnitude of the friction force while the bridge girder 1 is moving. EXAMPLES

[0051] Example 1 showing a specific configuration of the displacement control structure for bridge girders according to the embodiment described above will be described below with reference to Figures 5 and 6. Note that the same terms or symbols are used to describe the same or equivalent parts as those described in the embodiment described above.

[0052] Fig. 5 is an explanatory diagram showing the configuration of the bridge girder displacement control structure of Example 1, and Fig. 6 is a perspective view explaining the configurations of the side support member 3B and the friction adjustment plate 52B of Example 1. As a specific configuration of the base part 4, the head of the fixed anchor 42 is fixed to the bottom surface formed by a rectangular steel plate, and the rectangular plate-shaped friction adjustment plate 52B is joined to the upper surface 41 of the base part 4 by welding or the like.

[0053] The upper surface of the friction adjustment plate 52B, which serves as the sliding surface, is finished as described above according to the desired friction coefficient. In addition, the friction adjustment plate 52B is formed with a long groove 521, one end of which is open and through which the shaft of the bolt 51 is inserted.

[0054] The long groove 521 formed in the friction adjustment plate 52B of the first embodiment extends in the direction perpendicular to the bridge axis R1, and the end opposite the bridge girder 1 is open. The bottom plate of the main body 31 of the side support member 3B is placed on the upper surface of this friction adjustment plate 52B.

[0055] In short, the bolt joint 5B of the first embodiment is joined to the bottom plate (31) of the side support member 3B on the base portion 4 via the friction adjustment plate 52B by the bolt 51. The shaft of the bolt 51 passes through the long groove 521, the lower end of the bolt 51 is fixed to the lower surface of the friction adjustment plate 52B, and the upper end of the bolt 51 is fixed to the upper surface of the bottom plate (31) of the side support member 3.

[0056] For example, one end of the arm portion 32 formed by a pair of steel plates spaced apart in the bridge axis direction is joined to the main body portion 31, and an end portion 33 is formed of a steel plate or the like at the tip that projects from the main body portion 31. The vertical surface of this end portion 33 is brought into contact with the side surface of the end stiffener 13 of the bridge girder 1.

[0057] When a medium-scale or larger earthquake occurs and the end 33 of the side support member 3B is pushed by the bridge girder 1 with a force exceeding a predetermined value, the bolt 51 moves along the long groove 521 together with the side support member 3B. Then, the bolt 51 that reaches the open end of the long groove 521 will gradually come out of the long groove 521.

[0058] In other words, even if the side support member 3B moves significantly in the direction perpendicular to the bridge axis R1, the friction adjustment plate 52B does not prevent the movement of the bolt 51, and therefore excessive force can be prevented from acting on the base portion 4 to which the friction adjustment plate 52B is joined.

[0059] In the bridge girder displacement control structure of Example 1 configured in this manner, one end of the long groove 521, through which the bolt 51 of the friction adjustment plate 52B is inserted, is open, so that even if the amount of movement of the side support member 3B increases, it is possible to prevent the fixed anchor 42 that secures the base portion 4 from being pulled out, thereby preventing the bridge pier M, etc. from being damaged.

[0060] Furthermore, the friction adjustment plate 52B fixed to the upper surface 41 of the base portion 4 can generate a designed friction force between itself and the underside of the bridge girder 1 as well, thereby absorbing the energy due to the earthquake force. Other configurations and effects are substantially the same as those of the above-described embodiment or other examples, and therefore description thereof will be omitted. EXAMPLES

[0061] Hereinafter, an embodiment of a bridge girder displacement control structure other than the above-mentioned Example 1 will be described with reference to Fig. 7. Note that the same or equivalent parts as those described in the above-mentioned embodiment or other examples will be described with the same terms or symbols.

[0062] In the above-described embodiment 1, the friction adjustment plate 52B is provided on the base portion 4 side, but in the present embodiment 2, the friction adjustment plate 52C is provided on the side of the side support member 3C. The rectangular friction adjustment plate 52C is joined to the lower surface of the arm portion 32 of the side support member 3C by welding or the like.

[0063] The friction adjustment plate 52C is formed with a long groove 522 having one open end and through which the shaft of the bolt 51 is inserted. The long groove 522 formed in the friction adjustment plate 52C of the second embodiment extends in the direction R1 perpendicular to the bridge axis, and has an open end on the bridge girder 1 side. Then, the upper plate 411 forming the upper surface of the base part 4C is overlapped on the lower surface of this friction adjustment plate 52C.

[0064] In short, in the bolt joint 5C of the second embodiment, the side support member 3C is joined to the upper plate 411 of the base portion 4C via the friction adjustment plate 52C by the bolt 51. The shaft portion of the bolt 51 passes through the long groove 522, the upper end of the bolt 51 is fixed to the upper surface of the friction adjustment plate 52C, and the lower end of the bolt 51 is fixed to the lower surface of the upper plate 411 of the base portion 4C.

[0065] When a medium-scale or larger earthquake occurs and the end 33 of the side support member 3C is pushed by the bridge girder 1 with a force exceeding a predetermined value, the side support member 3C moves using the long groove 522 as a guide relative to the bolt 51 remaining on the pedestal 4 side. Then, the bolt 51 that has reached the open end of the long groove 522 will come out of the long groove 522 in order, starting with the bolt 51 on the bridge girder 1 side.

[0066] In the bridge girder displacement control structure of Example 2 configured in this manner, one end of the long groove 522, through which the bolt 51 of the friction adjustment plate 52C is inserted, is also open, so that even if the amount of movement of the side support member 3C increases, it is possible to prevent the fixed anchor 42 fixing the base portion 4C from being pulled out, thereby preventing damage to the bridge pier M, etc. Other configurations and effects are substantially the same as those of the above-described embodiment or other examples, and therefore description thereof will be omitted. EXAMPLES

[0067] Hereinafter, an embodiment of a bridge girder displacement control structure other than the above-mentioned Examples 1 and 2 will be described with reference to Fig. 8. Note that the same terms or the same reference numerals will be used to describe the same or equivalent parts as those described in the above-mentioned embodiment or other examples.

[0068] In the bridge girder displacement control structure of Example 3, not only is the end 33D of the side support member 3D brought into contact with the side of the bridge girder 1, but the end 33D is formed into a shape that allows the side support member 3D to move in response to displacement of the bridge girder 1 in the bridge axis direction R2.

[0069] In detail, a recess 331 capable of clamping the end stiffener 13 of the bridge girder 1 is provided at the end 33D of the side support member 3D, and the side edge of the end stiffener 13 is housed in the recess 331. This makes it possible to perform displacement control not only when the bridge girder 1 moves in the direction orthogonal to the bridge axis R1, but also when it moves in the bridge axis direction R2.

[0070] The bolt joint 5D provided between the side support member 3D and the base 4 in the third embodiment is formed so that slip occurs in both the bridge axis orthogonal direction R1 and the bridge axis direction R2. In detail, the bolt joint 5D includes a friction adjustment plate 54 arranged on the side support member 3D side, a friction adjustment plate 55 provided on the base 4 side, and an intermediate portion 53 provided between the upper and lower friction adjustment plates 54, 55.

[0071] The upper friction adjustment plate 54 has a long groove 541 that extends in the bridge axis direction R2 and has one open end, through which the shaft of the bolt 51 is inserted. The bottom plate of the main body 31 of the side support member 3D is placed on the upper surface of the friction adjustment plate 54 and joined by the bolt 51.

[0072] On the other hand, the lower friction adjustment plate 55 has a long groove 551 that extends in the direction perpendicular to the bridge axis R1 and has one open end, through which the shaft of the bolt 51 is inserted. The bottom plate of the middle part 53 is placed on the upper surface of the friction adjustment plate 55 and joined by the bolt 51.

[0073] When a medium-scale or larger earthquake occurs and the bridge girder 1 moves in the direction perpendicular to the bridge axis R1, slippage occurs along the long groove 551 of the friction adjustment plate 55. When the bridge girder 1 moves in the bridge axis direction R2, slippage occurs along the long groove 541 of the friction adjustment plate 54.

[0074] The displacement control structure of the bridge girder of Example 3 configured in this manner is configured so that the side support member 3D and the bolt joint 5D can be displaced in the bridge axis direction R2 and the direction orthogonal to the bridge axis R1, and therefore can control not only the displacement in the direction orthogonal to the bridge axis R1, but also the displacement in the bridge axis direction R2. Other configurations and effects are substantially the same as those of the above-described embodiment or other examples, and therefore description thereof will be omitted. EXAMPLES

[0075] Hereinafter, an embodiment of a bridge girder displacement control structure other than the above-mentioned Examples 1-3 will be described with reference to Fig. 9. Note that the same or equivalent parts as those described in the above-mentioned embodiment or other examples will be described with the same terms or symbols.

[0076] In the displacement control structure for a bridge girder in Example 4, it becomes possible to control displacement in all directions by using a bolt joint 5E different from the bolt joint 5D in the above-mentioned Example 3. In detail, an insertion hole 561 having a diameter larger than the shaft of the bolt 51 to be inserted is drilled in the friction adjustment plate 56 of the bolt joint 5E.

[0077] This friction adjustment plate 56 is interposed between the upper plate 411 of the base portion 4C and the main body portion 31 of the side support member 3D, and the upper end of the bolt 51, whose shaft portion is passed through the insertion hole 561, is fixed to the upper surface of the main body portion 31, and the lower end of the bolt 51 is fixed to the lower surface of the upper plate 411.

[0078] When a medium-sized or larger earthquake occurs and the end 33D of the side support member 3D is pushed by the end stiffener 13 of the bridge girder 1 housed in the recess 331 with a force exceeding a predetermined value, slippage accompanied by friction occurs, causing the side support member 3D to move within the range in which the shank of the bolt 51 in the insertion hole 561 can move freely.

[0079] In the bridge girder displacement control structure of Example 4 configured in this manner, the insertion hole 561, through which the bolt 51 of the friction adjustment plate 56 is inserted, is formed larger than the shaft portion of the bolt 51, so that the side support member 3D can be moved in all directions, not just in the direction R1 perpendicular to the bridge axis. Other configurations and effects are substantially the same as those of the above-described embodiment or other examples, and therefore description thereof will be omitted. EXAMPLES

[0080] Hereinafter, an embodiment of a bridge girder displacement control structure other than the above-mentioned Examples 1-4 will be described with reference to Fig. 10. Note that the same terms or the same reference numerals will be used to describe the same or equivalent parts as those described in the above-mentioned embodiment or other examples.

[0081] In the displacement control structure for a bridge girder in Example 5, the end 33E of the side support member 3E serves as a friction surface material. That is, the end 33E that comes into contact with the side of the bridge girder 1 is formed in a rectangular plate shape with an adjusted friction coefficient, and when the bridge girder 1 moves in the bridge axis direction R2, energy is absorbed by the friction force.

[0082] In the bridge girder displacement control structure of Example 5 configured in this manner, the end 33E of the side support member 3E is formed from a friction surface material that does not restrict displacement in the bridge axis direction R2 of the bridge girder 1. Therefore, when displacement in the bridge axis direction R2 occurs in the bridge girder 1, a damping force can be generated against the movement of the bridge girder 1 due to slippage accompanied by friction that occurs between the side surface of the bridge girder 1 and the friction surface material of the end 33E. Other configurations and effects are substantially the same as those of the above-described embodiment or other examples, and therefore description thereof will be omitted.

[0083] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment or example, and design changes that do not deviate from the gist of the present invention are included in the present invention. [Explanation of symbols]

[0084] 1: Bridge girder 13: End stiffener (side) 2: Bearing part 21: Support surface 3,3A-3E: Side support member 33,33D,33E: End 4, 4C: Base 41:Top surface 5,5A-5E: Bolted joints 51: Bolt 52,52B,52C:Friction adjustment plate 521, 522: Nagamizo 54,55:Friction adjustment plate 541,551: Nagamizo 56:Friction adjustment plate 561: Insertion hole M: Pier R1: Perpendicular to the bridge axis R2: Bridge axis direction

Claims

1. A bridge girder displacement control structure that controls the displacement of a bridge girder during an earthquake, A side support member whose end portion contacts the side surface of the bridge girder in the direction perpendicular to the bridge axis; A base portion arranged adjacent to the support portion of the bridge girder in a direction perpendicular to the bridge axis and fixed to a bridge pier or abutment; a bolt joint portion for bolting a lower portion of the side support member onto the base portion, In the bolt joint, when a force acting from the bridge girder to the side support member exceeds a predetermined value, slippage occurs and the side support member moves, A displacement control structure for a bridge girder, characterized in that the surface of the base portion exposed after the movement of the side support member is formed to be approximately the same height as the support surface of the bearing portion on which the bridge girder is placed.

2. A bridge girder displacement control structure that controls the displacement of a bridge girder during an earthquake, A side support member whose end portion contacts the side surface of the bridge girder in the direction perpendicular to the bridge axis; A base portion arranged adjacent to the support portion of the bridge girder in a direction perpendicular to the bridge axis and fixed to a bridge pier or abutment; a bolt joint portion for bolting a lower portion of the side support member onto the base portion, In the bolt joint, when a force acting from the bridge girder to the side support member exceeds a predetermined value, slippage occurs and the side support member moves, A displacement control structure for a bridge girder, characterized in that the bolt joint portion is provided with a friction adjustment plate interposed between the base portion and the side support member.

3. The displacement control structure for a bridge girder as described in claim 1 or 2, characterized in that a surface formed on the base portion and exposed after the movement of the side support member protrudes toward the support portion.

4. 3. The bridge girder displacement control structure according to claim 2, wherein the friction adjustment plate has a long groove, one end of which is open and through which a bolt is inserted.

5. 3. The bridge girder displacement control structure according to claim 2, wherein the friction adjustment plate has an insertion hole having a diameter larger than that of the shaft portion of the bolt through which the bolt is inserted.

6. The end of the side support member is formed in a shape that allows the side support member to move in accordance with the displacement of the bridge girder in the bridge axis direction, A displacement control structure for a bridge girder as described in any one of claims 1 to 5, characterized in that at the bolt joint, slip occurs in the bridge axis direction or in a direction perpendicular to the bridge axis depending on the direction of force acting from the bridge girder to the side support member.

7. The displacement control structure for a bridge girder according to any one of claims 1 to 5, characterized in that the end portion of the side support member is formed of a friction surface material.

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