JP7682452B2 - Bridge collapse prevention device - Google Patents

Description

The present invention relates to a bridge fall prevention device for preventing bridge girders from falling.

Bridges are equipped with fall prevention devices that connect the bridge girders and abutments to prevent the bridge girders (superstructure) from falling from the abutments and piers (substructure) during an earthquake.

However, in conventional bridge fall prevention devices, when excessive external forces such as earthquake forces are applied, a large impact force can act on them, raising concerns about damage. As a countermeasure to this, for example, a bridge fall prevention device with three-dimensional brackets is known, which connects both ends of a viscous damper with brackets between the bridge girder and abutment (Patent Document 1).

JP 2019-52532 A

However, conventional bridge fall prevention devices typically use oil dampers, which pose the following problems. Namely, oil dampers have a structure that absorbs energy by moving the oil sealed inside, and therefore have the problems of taking time to operate and being temperature dependent. Also, because it is necessary to provide oil dampers in addition to the original mechanism of the bridge fall prevention device, the structure is complex and the entire device is large, which inevitably results in high manufacturing costs and complicated maintenance, including inspection.

From this perspective, the objective of the present invention is to provide a bridge collapse prevention device that is responsive, has no temperature dependency, has high shock absorption performance, is easy to maintain, has a simple structure, and is inexpensive.

In order to solve the above problem, the bridge fall prevention device of the present invention has a first support member for attachment to one of the superstructure or the substructure, and a second support member for attachment to the other of the substructure or the superstructure, which is provided opposite the first support member, the first support member and the second support member are slidably joined via fastening means that penetrates the first support member and the second support member and can be brought into contact with or separated from each other within the range of a long hole formed in the second support member, and a frictional force generating means is provided that generates a frictional force corresponding to the relative displacement between the first support member and the second support member, the frictional force generating means comprising an intervening member interposed between the first support member and the second support member and having a central hole through which the fastening means passes, and an impact absorbing member is provided on a part of the abutment surface of the first support member or the second support member with the intervening member, and the first support member and the second support member are clamped with a predetermined clamping force via the fastening means, thereby generating the frictional force between the first support member, the second support member, and the intervening member .

The bridge fall prevention device of the present invention for solving the above-mentioned problem may comprise a first support member for attachment to either the superstructure or the substructure, and a second support member for attachment to the other of the substructure or the superstructure, which is arranged opposite the first support member, wherein the first support member and the second support member are slidably joined via a fastening means which penetrates the first support member and the second support member, and are capable of coming into contact with or separating from each other within the range of a long hole formed in the second support member, a friction force generating means is provided which generates a friction force in response to the relative displacement between the first support member and the second support member, and an impact absorbing member is provided on the mounting surface of at least one of the first support member and the second support member with the superstructure or the substructure .

In addition, in the bridge fall prevention device of claim 2 of the present invention, the friction force generating means may be configured to generate the friction force between the first support member and the second support member by clamping the first support member and the second support member with a predetermined clamping force.

In addition, in the bridge fall prevention device of claim 2 of the present invention, the friction force generating means may be configured so that a friction force enhancing means is provided on the sliding surfaces of the first support member and the second support member.

In addition, in the bridge fall prevention device of claim 2 of the present invention, the friction force generating means may include an intervening member interposed between the first support member and the second support member and having a central hole through which the fastening means passes, and the friction force may be generated between the first support member, the second support member, and the intervening member by clamping the first support member and the second support member with a predetermined clamping force via the fastening means .

In addition, in the bridge fall prevention device of the present invention, the multiple intervening members may be configured to be connected together or arranged side by side at a predetermined interval in the longitudinal direction of the first support member and the second support member .

In addition, in the bridge fall prevention device of the present invention, the first support member has a base plate and side plates arranged longitudinally at intervals in the width direction perpendicular to the base plate, and the second support member has a central plate arranged longitudinally between the side plates, an end plate arranged at an end of the central plate, and the impact absorbing member arranged on the end plate, and the central plate may be configured so that the hole of the fastening means that penetrates the side plates and the central plate is formed as the long hole in the longitudinal direction .

In addition, in the bridge fall prevention device of the present invention, the central plates may be arranged in multiple rows in the width direction and positioned between the side plates, and the intervening members may be configured to be positioned between the central plates and the side plates .

Furthermore, in the bridge fall prevention device of the present invention, if the central plate, the side plates, and the renovation members are arranged side by side in the spacing direction, this is preferable because it effectively suppresses the widthwise deformation performance of the intervening members and improves the friction force generation effect.

In addition, in the bridge fall prevention device of the present invention, the friction force generating means has a friction force generating range larger than the displacement range of the first support member and the second support member, which is preferable because it prevents the friction force generating means from being damaged before the bridge fall prevention function is lost. Furthermore, in the bridge fall prevention device of the present invention, the friction force generating means includes a first metal surface provided on the sliding surface of the first support member and made of a metal material different from that of the first support member, and a second metal surface provided on the sliding surface of the second support member and made of a metal material different from that of the second support member, and the first metal surface and the second metal surface may be formed of metal-based sliding materials made of metal materials with different component compositions.

According to the present invention, since a friction force generating means is provided, a friction force is generated in response to the relative displacement of the first and second support members, and when an external force such as an earthquake is applied, the operation of the bridge fall prevention device is slowed down, and when the first and second support members are displaced, the external force can be absorbed and attenuated by the friction force. Therefore, since it is possible to create a device that prevents the bridge from falling while absorbing earthquake energy, it is possible to prevent the bridge fall prevention device from suddenly being subjected to an impact force that could cause damage to the bridge girders or abutments.

The Highway Bridge Specifications stipulate that, in order to prevent the loss of one function from leading to the loss of the other and to ensure that each function is maintained, in principle, bridge fall prevention structures and displacement restriction structures must not be used together. However, the Highway Bridge Specifications contain an exception that stipulates that they may be used together if a structure is adopted that can ensure both functions independently, and as this bridge fall prevention device is designed to ensure the functions of the bridge fall prevention structure and displacement restriction structure independently, no problems will arise.

The bridge fall prevention device of the present invention has quick response, is not temperature dependent, has high shock absorption performance, is easy to maintain, and has a simple structure and is inexpensive.

1 is a side view showing a bridge fall prevention device (first embodiment) of the present invention applied to a bridge. This is a cross-sectional view taken along line II-II in FIG. 1 is a side view showing a bridge fall prevention device (first embodiment) of the present invention. 1 is a plan view showing a bridge fall prevention device (first embodiment) of the present invention. 1 is a side view showing a case where an earthquake force acts on a bridge fall prevention device (first embodiment) of the present invention. FIG. 1 is a side view showing the bridge fall prevention device (first embodiment) of the present invention when displaced within the expected limit range. FIG. 1 is a plan view showing the bridge fall prevention device (first embodiment) of the present invention when displaced within the expected limit range. FIG. 1 is a graph showing the relationship between the amount of displacement of the bridge fall prevention device and the impact force acting on the bridge. FIG. 11 is a side view showing the case where the bridge fall prevention device of the present invention is applied to another bridge. 10 is a cross-sectional view taken along the line XX in FIG. 9 . FIG. 2 is a side view showing a bridge fall prevention device (second embodiment) of the present invention. FIG. 2 is a plan view showing a bridge fall prevention device (third embodiment) of the present invention. A side view showing the bridge fall prevention device of the present invention (fourth embodiment). FIG. 13 is a plan view showing the bridge fall prevention device of the present invention (fifth embodiment). A plan view showing the bridge fall prevention device of the present invention (sixth embodiment). FIG. 16 is a side view of the bridge fall prevention device of FIG. 15 . 16 is a side view showing the disassembled state of the bridge fall prevention device of FIG. 15.

Below, we will explain in detail one embodiment of the bridge fall prevention device S1 of the present invention (hereinafter referred to as "this bridge fall prevention device") with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals and duplicate explanations are omitted.

(Configuration of this bridge fall prevention device)
This bridge fall prevention device S1 is installed between the bridge girder G of the bridge B (first embodiment) and the abutment P, and is used to prevent the bridge girder G from falling by connecting the bridge girder G and the abutment P, and is installed at multiple specified locations.
1 and 2, the bridge fall prevention device S1 is interposed between a concrete wall G1 protruding from the underside near the support part J at the end of the bridge girder G and the opposing upper side surface of the abutment P. Also, the locations where the first support member 10 and the second support member 20 are attached by anchor bolts 41 at their mounting parts 15, 25 are shown as examples here.

First, the configuration of the bridge fall prevention device S1 will be described.
As shown in Figures 3 and 4, the main components of this bridge fall prevention device S1 are a first support member 10, a second support member 20 arranged opposite the first support member 10 in the horizontal direction (X direction), and an intermediate plate 30 (intermediate member) and PC steel rod 31 (fastening means) which are friction force generating means.

The first support member 10 includes a base plate 11 formed in the width direction (Y direction), two side plates 12 arranged in a direction perpendicular to the base plate 11, and an attachment portion 15 provided on the base plate 11. The side plates 12 are formed at intervals from each other in the direction perpendicular to the base plate 11 (X direction). A steel rod insertion hole 12a for inserting a PC steel rod 31 is formed at a position slightly away from the center of the side plates 12 on both sides toward the opposing side opposite the base plate 11 (hereinafter referred to as the "tip side"). In addition, the side plates 12 are formed with small bolt holes 12b for inserting the attachment bolts 32 of the intermediate plate 30 at equal intervals with the steel rod insertion hole 12a in the center, and a bolt hole 12c for inserting a side stop bolt 33 is formed on the base end side.

The second support member 20 includes a central plate 22 in the longitudinal direction, an end plate 21 provided at the end of the central plate 22 on the first support member 10 side, and an attachment portion 25 provided at the end of the central plate 22. A long hole 22a is formed in the longitudinal direction at the center of the central plate 22, and a shock absorber 23 (shock absorbing member) is provided on the contact surface between the end plate 21 and the intermediate plate 30, which is on the inside of the end plate 21 (hereinafter, the T-shaped member formed by the end plate 21, central plate 22, and shock absorbing member 23 may be referred to as a "T-shaped portion 24").
The first support member 10 and the second support member 20 are formed from steel plates of the same steel type.

Moreover, the mounting portions 15, 25 of the first support member 10 and the second support member 20 are formed in the same shape, for example.
The mounting portion 15 of the first support member 10 is formed of a vertical plate 16 and a horizontal plate 17 that is horizontally disposed at a predetermined distance in the height direction of the vertical plate 16. A central hole 17a is formed in the center of each horizontal plate 17. The base plate 11 is fixed between the two horizontal plates 17. A cylinder 18 is inserted into the central hole 17a, and a pin 19 is fitted into the cylinder 18.

The mounting portion 25 of the second support member 20 is formed from a vertical plate 26 and a horizontal plate 27 that is horizontally arranged at a predetermined distance in the height direction of the vertical plate 26. A central hole 27a is formed in the center of each horizontal plate 27. An end of the central plate 22 is fixed between the two horizontal plates 27. A cylinder 28 is inserted into the central hole 27a, and a pin 29 is inserted into the cylinder 28.

The intermediate plate 30 is a steel plate having a substantially square shape. The intermediate plate 30 is covered in a circular area at the center of one side with, for example, polytetrafluoroethylene (PTFE) to form a circular covering portion 30a. A central hole 30b for inserting a PC steel rod 31 is formed at the center of the circular covering portion 30a. The diameter of the circular covering portion 30a is formed to be longer than the length of the long hole 22a of the central plate 22 of the second support member 20, and the frictional force generating range (operating range) of the frictional force generating means is larger than the displacement range of the first support member 10 and the second support member 20.

The intermediate plate 30 is disposed opposite the side plate 12 so that one end of the intermediate plate 30 is substantially aligned with the tip end of each side plate 12. Furthermore, the intermediate plate 30 is disposed so that the circular covering portion 30a faces the central plate 22. The intermediate plate 30 is attached integrally to the side plate 12 by inserting the mounting bolts 32 that communicate with the four small bolt holes 12b of the side plate 12.
The second support member 20 is arranged so that when the side plates 12 or the central plate 22 of both first support members 10 are positioned at the moving ends, the end faces of the end plates 21 come into contact therewith to absorb impact.

The steel rod insertion hole 12a of the side plate 12 of the first support member 10, the central hole 30b of each intermediate plate 30, and the long hole 22a of the central plate 22 of the second support member 20 are aligned, and PC steel rods 31 are inserted into each hole. The first support member 10 and the second support member 20 are joined via the intermediate plate 30 by tightening the PC steel rods 31 with a predetermined tension. In addition, side stop bolts 33 are inserted into the bolt holes 12c of the two side plates 12, and a clamping force is applied between the two side plates 12. The reference numeral 14 denotes a backing plate that is interposed between the head of the side stop bolt 33 and the side plate 12 in order to fasten the side stop bolt 33 to the side plate 12.

With the above-mentioned configuration, the side plate 12 of the first support member 10 and the central plate 22 of the second support member 20 are rotatably supported relative to the PC steel rod 31, which is the horizontal rotation axis, and are also slidable and separable horizontally within the range of the long hole 22a formed in the central plate 22 of the second support member 20.
The dynamic friction coefficient of the circular covering portion 30a of the intermediate plate 30 is smaller than that of the central plate 22 of the second support member 20. However, the side plate 12, the intermediate plate 30, and the central plate 22 are sandwiched together by the tension of the PC steel rod 31, and a predetermined clamping force is applied to the intermediate plate 30, so that when the side plate 12 of the first support member 10 and the central plate 22 of the second support member 20 are displaced, a friction force of a predetermined magnitude is generated. Also, the range of the area where the circular covering portion 30a is formed is wider than the range of the area of the long hole 22a.

(Actions and Effects of this Bridge Fall Prevention Device)
Next, the operation of the bridge fall prevention device S1 will be explained.
For example, when an earthquake occurs and an earthquake force (external force) acts on the bridge girder G and the abutment P, the bridge girder G and the abutment P are displaced according to the magnitude and direction of the earthquake force. At this time, the bridge fall prevention device S1 rotates by displacing the side plate 12 of the first support member 10 and the central plate 22 of the second support member 20 in the vertical direction with the center of the PC steel bar 31 as the rotation center (FIG. 5). Furthermore, the bridge fall prevention device S1 displaces in response to the earthquake force by horizontally separating the side plate 12 of the first support member 10 and the central plate 22 of the second support member 20 within the range of the long hole 22a of the central plate 22 of the second support member 20, thereby preventing the bridge girder G from falling from the abutment P (FIGS. 6 and 7).

At this time, in this bridge fall prevention device S1, the intermediate plate 30 is clamped by the axial force of the PC steel rod 31, and the movement of this intermediate plate 30 is restricted by the circular covering portion 30a, which is the sliding surface (contact surface) with the central plate 22 of the second support member 20. Therefore, in this bridge fall prevention device S1, when the central plate 22 of the second support member 20 is displaced, a frictional force is generated via the circular covering portion 30a, and this frictional force can absorb and attenuate the impact force acting on this bridge fall prevention device S1 due to seismic forces.

In this way, according to the bridge fall prevention device S1, a friction force generating means is provided as a damping mechanism that generates friction force by the action of the intervening plate 30 with the circular covering portion 30a and the PC steel rod 31 in response to the relative displacement of the first support member 10 and the second support member 20. Therefore, when an external force such as an earthquake occurs, the bridge fall prevention device S1 operates, and the first support member 10 and the second support member 20 are displaced, the external force can be damped by the friction force, and it is possible to prevent sudden impact forces from acting on the bridge fall prevention device S1. Therefore, it is possible to realize a simple and inexpensive structure, and compared to conventional bridge fall prevention devices that use dampers, it is possible to achieve a structure that is more responsive and has no temperature dependency, and to improve impact absorption performance.

Figure 8 is a graph showing the relationship between the amount of displacement of the bridge fall prevention device S1 and the impact force acting on the bridge (bridge girder or abutment, etc.). According to the same figure, in the case of a bridge fall prevention device that does not have a friction force generating means, an impact force will act suddenly when the expected limit of displacement is reached. On the other hand, in the case of the bridge fall prevention device S1, the impact force acts gradually, and it can be seen that damage to the bridge can be effectively prevented.

In addition, in this bridge fall prevention device S1, a shock absorber 23 is provided on the contact surface of the end of the intermediate plate 30, which is inside the end plate 21 of the second support member 20. Therefore, even if the first support member 10 and the second support member 20 separate within the expected limit, the action of the shock absorber 23 makes it possible to effectively prevent impact forces from acting on this bridge fall prevention device S1, thereby preventing damage to it (Figure 8).

In addition, in this bridge fall prevention device S1, the diameter of the circular covering portion 30a is formed to be longer than the length of the long hole 22a of the center plate 22 of the second support member 20. Therefore, in this bridge fall prevention device S1, the friction force generation range (operating range) of the friction force generating means is larger than the displacement range of the first support member 10 and the second support member 20. By configuring it in this way, in this bridge fall prevention device S1, it is possible to continue the action of the friction force generating means for a long time and prevent damage by allowing the friction damping effect to be in effect even after the bridge fall prevention function is lost, without complicating the component configuration or incurring excessive manufacturing costs.

(Other embodiments of the bridge fall prevention device)
The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment, and each of the above components can be appropriately modified without departing from the spirit of the present invention.

For example, the first support member and the second support member may be interposed between the upper structure and the lower structure by attaching one of them to the upper structure or the lower structure and attaching the other to the lower structure or the upper structure.

In this regard, in the above embodiment, the bridge fall prevention device S1 has been described as an example in which the mounting portion 15 of the first support member 10 is attached to the bridge abutment P of the first embodiment, and the mounting portion 25 of the second support member 20 is attached to the bridge girder G.
However, when applying the bridge fall prevention device S1 to the bridge BB of the second embodiment having a space between the deck GG2 and the cross beam GG1 at the end (FIGS. 9 and 10), the mounting portion 25 of the second support member 20 can be attached to the end of the abutment PP, and the mounting portion 15 of the first support member 10 can be attached to the cross beam GG1. That is, in the bridge BB of the second embodiment, it is also possible to adopt a structure in which the mounting portion 25 of the second support member 20 is attached to the concrete wall portion PP1 protruding from the upper portion of the abutment PP, and the mounting portion 15 of the first support member 10 is attached to the lower end on the inside of the cross beam GG1.

The first support member, second support member, frictional force generating means, frictional force enhancing means and shock absorbing member described in the claims may use various components as long as they have the basic configuration and provide the desired effect, and their configuration (shape, dimensions, material, etc.) may be determined as appropriate.

In particular, the first support member and the second support member are supported so as to be rotatable about a horizontal rotation axis due to the action of external forces caused by earthquake forces, etc., and are configured to be appropriately displaceable so that they can approach and move away from each other horizontally. The displacement form and amount of displacement, etc. can be appropriately determined depending on the magnitude of the expected external force.
The first and second support members can be configured to rotate in any direction by using a universal joint. In addition, the first and second support members can be slidably moved while directly contacting each other, or can be slidably moved indirectly through an intervening member as in this embodiment.

Furthermore, the friction force generating means may be any means that generates a friction force in response to relative displacement in any direction between the first support member and the second support member, and various means may be used for the first support member and the second support member, such as using members with a large dynamic friction coefficient for the first support member and the second support member, or coating at least one of them with an appropriate material, and interposing an interposing member between the first support member and the second support member.
In particular, it is also preferable to provide a frictional force enhancing means by forming a rough surface or a plurality of projections and recesses on the sliding surface of the first support member or the second support member.

The bridge fall prevention device according to the second to sixth embodiments will be described below with reference to Figures 11 to 17. Members having the same configuration as those already described in the following embodiments will be given the same reference numerals as those in the bridge fall prevention device according to the first embodiment, and the description will be omitted as appropriate.
As shown in the second embodiment of the bridge fall prevention device S2 (FIG. 11), a configuration in which a plurality of friction force generating means, namely, interposition plates 30 (interposition members) and PC steel rods 31 (fastening means), are consecutively arranged in the longitudinal direction of the side plate 212 of the first support member 210 (arranged side by side with no gap between adjacent interposition plates 30) can also be adopted (reference numeral 222a denotes a long hole formed at a predetermined position in the central plate 222 of the second support member 220). In this way, by adopting the above configuration, it is possible to effectively suppress deformation of the interposition plates 30 in the longitudinal direction and improve the friction force generating effect.

Furthermore, a plurality of frictional force generating means may be arranged in parallel in the spacing direction between the first support member and the second support member.
For example, as shown in the third embodiment of the bridge fall prevention device S3 (Figure 12), a configuration in which multiple intervening plates 330 are provided in the width direction of the first support member 310 and the second support member 320 will be described.

In this case, a central plate 313 (reference numeral 311 indicates a base plate) is provided between two side plates 312 that correspond to the side plates 12 on both sides of the first support member 10 in the bridge girder fall prevention device S1 of the first embodiment. In addition, two T-shaped portions 324 (reference numerals 321 and 323 indicate end plates and shock absorbers 323, respectively) that have a structure similar to that of the T-shaped portion 24 that constitutes the second support member 20 are extended from the mounting portion 325.

The T-shaped portions 324 are inserted between the side plates 312 and the central plate 313 of the first support member 310 so as to be slidable. A total of four intermediate plates 330 are interposed between the side plates 312 of the first support member 310 and the central plate 322 of the second support member 320, and between the central plate 313 of the first support member 310 and the central plate 322 of the second support member 320, so that the intermediate plates 330 are arranged in parallel in the width direction between the first support member 310 and the second support member 320 (reference numeral 331 denotes a PC steel bar for applying a clamping force to each member, and 322a denotes an elongated hole formed in the central plate 322). With the above configuration, when the circular covering portion 330a of the intermediate plate 330 slides against each central plate 313, 322, a frictional force is generated through the circular covering portion 330a.

The structure of each mounting portion 315, 325 of the first support member 310 and the second support member 320 is the same as the structure of each mounting portion 15, 25 in the bridge fall prevention device S1 of the first embodiment. The intermediate plate may be divided into appropriate dimensions, such as a laminated structure, and a plurality of plates may be arranged, or the entire plate may be covered with a covering material. The circular covering portions 30a, 330a may be covered to have a rectangular or elliptical shape . Furthermore , the circular covering portions 30a, 330a may be formed by combining metals and resins with different performances, such as stainless steel (SUS) and polytetrafluoroethylene resin (PTFE)/polyamide, or by combining steel materials with different properties, and various combinations of constituent materials may be used, such as combining high-strength brass steel and stainless steel, PEEK and stainless steel, or PBN and stainless steel.
In this way, according to the bridge fall prevention device S3 of the third embodiment, it is possible to effectively suppress deformation of the intermediate plate 330 in the width direction and improve the friction force generation effect.

In addition, in order to ensure stable operation of the friction force generating means, it is desirable to keep the dynamic friction coefficient constant. However, it is not necessary to use a material with a larger dynamic friction coefficient for the intervening member than the first support member or the second support member. In the above embodiment, if a material with a smaller dynamic friction coefficient for the intervening member than the first support member and the second support member is used for the intervening member in order to facilitate control, this can be achieved by applying an appropriate clamping force to set the magnitude of the generated friction force.

In addition, the installation location, number of installations, and installation method of this bridge fall prevention device can be determined appropriately depending on the type of bridge to which it is installed.

In addition, the shock absorbing member provided on a part of the contact surface of the first support member or the second support member with the intermediate member, and on the mounting surface of at least one of the first support member and the second support member with the upper structure or the lower structure, can be constructed as a member of the desired material and shape, such as various elastic bodies (low-resilience rubber, polyurethane, etc.).

In this regard, for example, as shown in the fourth embodiment of the bridge fall prevention device S4 (Fig. 13), a shock absorber 42 can be interposed between each mounting portion 15, 25 of the first support member 10 and the second support member 20 and the bridge girder G and abutment P. With the above configuration, the shock absorber 42 can effectively prevent impact forces from acting on the bridge fall prevention device S4, preventing damage to the device (Fig. 8).

Furthermore, as shown in FIG. 14 for the fifth embodiment, the bridge fall prevention device S5 may be configured to form one end 30B1 of the intermediate plate 30B in an arc shape. In addition, the bridge fall prevention device S5 may be configured to attach stainless steel plates 20b, 20b as metal-based sliding materials formed in a planar shape at a position facing the circular covering parts 30a, 30a on the front and back sides of the second support member 20 as mating plates for the circular covering parts 30a, 30a of the metal-based manual materials. In other words, the stainless steel plate 20b and the circular covering part 30a of the intermediate plate 30 may be formed of different metal-based sliding materials so that they face each other and become sliding surfaces. By forming one end 30B1 of the intermediate plate 30B in an arc shape, the shock absorber 23 can be evenly abutted against one end 30B1 of the intermediate plate 30B even if the first support member 10 and the second support member 20 are moved from the initial state, for example, as shown in FIG. 6. It is also more preferable to form the shock absorber 23 and the end plate 21 in an arc shape to match the shape of one end 30B1 of the intermediate plate 30B. Furthermore, by forming the sliding surface, which serves as a friction generating means, from a metal-based sliding material with a different composition, it is possible to eliminate seizure during sliding.

The sixth embodiment will be described with reference to Figs. 15 to 17. In this bridge fall prevention device S6, as a friction force generating means, a covering part 30c, which is a first metal surface formed of a metal material with a different composition from that of the first support member 10 provided on the sliding surface of the first support member 10, and a counter plate material, which is a second metal surface formed of a metal material with a different composition from that of the second support member 20 provided on the sliding surface of the second support member 20, are formed together with the PC steel bar 31. In addition, in this bridge fall prevention device S6, the shape of the intermediate plate 30C is formed so that one end 30C1 is arc-shaped and the other end is rectangular in a plan view. Here, the covering parts 30c, 30c may be configured to be formed rectangular in a plan view. The covering parts 30c, 30c are formed of a metal-based sliding material and are installed on one side and the other side across the long hole 22a. That is, the covering portions 30c, 30c are arranged so that two are on one of the intermediate plates 30 and two are on the other intermediate plate 30C. In addition, it is preferable that the front and back surfaces of the second member 20 facing the covering portions 30c, 30c are set with a metal material that has good adhesion resistance and affinity for the metal-based sliding material, for example, a mating plate material that is a metal-based sliding material such as a stainless steel plate 20c.

As the metal-based sliding material in the covering portion 30c, 30c, a fixed lubricant dispersion type sintered material, a copper-based powder sintered material, etc. can be used. The covering portion 30c, 30c is connected to the intermediate plate 30C, 30C as a sliding surface by welding or sintering. The covering portion 30c, 30c is formed into a rectangle, which makes it easier to handle than when it is formed into a circle, since it can be prepared by cutting a thin plate linearly at a certain interval. The covering portion 30c, 30c is formed of a metal material whose composition is different from the metal material used in the intermediate plate 30C, 30C. The stainless steel plate 20c is also formed of a metal material whose composition is different from the metal material of the end plate 21 of the second support member 20. In other words, since the covering portion 30c, 30c and the intermediate plate 30C, 30C have different roles, it is preferable to select a metal material whose composition is suitable for that role. Similarly, the end plate 21 of the second support member 20 and the mating plate material such as the stainless steel plate 20c have different roles, so it is preferable to select a metal material with a composition suitable for that role. Note that metal materials with different composition refer not only to metal materials with different contained components, but also to metal materials with the same contained components but with different amounts that change the function.

The metal-based sliding material can also be applied to the first and fourth embodiments already described. Although the covering parts 30c, 30c have been described as rectangular, they can be trapezoidal, parallelogram, arc-shaped, oval-shaped, or other shapes that can be used as sliding surfaces, and can be used as a configuration in which two pieces are installed on one of the intermediate plates 30C with the long hole 22a between them. Furthermore, as described in the first embodiment, when a circular covering part 30a is configured to have a long hole corresponding to the long hole 22a in the center and one piece is installed on one of the intermediate plates 30C, its external shape can be made similar to that of the intermediate plate 30.

S1 to S6 Bridge fall prevention device B, BB Bridge G, GG Bridge girder P, PP Abutment 10, 210, 310 First support member 11, 311 Base plate 12, 212, 312 Side plate 313 Center plate 15 Mounting portion 20, 220, 320 Second support member 20b, 20c Stainless steel plate (second metal surface: friction generating means)
21, 321 End plate 22, 222, 322 Center plate 322 Side plate 22a, 222a, 322a Long hole 23, 42 Shock absorber (shock absorbing member)
25 Mounting portion 30, 330 Intermediate plate (Intermediate member: Friction force generating means)
30a, 330a: Circular covering portion 30c: Covering portion (first metal surface: friction generating means)
31, 331 PC steel bar (fastening means: friction force generating means)

Claims (10)

a first support member for attachment to one of the upper structure or the lower structure;
a second support member provided opposite the first support member for attachment to the other of the lower structure or the upper structure;
the first support member and the second support member are slidably joined to each other via fastening means passing through the first support member and the second support member, and are movable toward and away from each other within a range of an elongated hole formed in the second support member;
a friction force generating means for generating a friction force corresponding to a relative displacement between the first support member and the second support member is provided;
the frictional force generating means includes an intermediate member interposed between the first support member and the second support member and having a central hole through which the fastening means passes;
An impact absorbing member is provided on a part of a contact surface between the first support member or the second support member and the intermediate member,
A bridge fall prevention device characterized in that the friction force is generated between the first support member, the second support member, and the intervening member by clamping the first support member and the second support member with a predetermined clamping force via the fastening means. a first support member for attachment to one of the upper structure or the lower structure;
a second support member provided opposite the first support member for attachment to the other of the lower structure or the upper structure;
the first support member and the second support member are slidably joined to each other via fastening means passing through the first support member and the second support member, and are movable toward and away from each other within a range of an elongated hole formed in the second support member;
a friction force generating means for generating a friction force corresponding to a relative displacement between the first support member and the second support member is provided;
A bridge fall prevention device characterized in that an impact absorbing member is provided on the mounting surface of at least one of the first support member and the second support member with the superstructure or the substructure. The friction force generating means is
A bridge fall prevention device as described in claim 2, characterized in that a friction force enhancing means is provided on the sliding surfaces of the first support member and the second support member. The friction force generating means is
A bridge fall prevention device as described in claim 2, characterized in that the friction force is generated between the first support member and the second support member by clamping the first support member and the second support member with a predetermined clamping force. the frictional force generating means includes an intermediate member interposed between the first support member and the second support member and having a central hole through which the fastening means passes;
A bridge fall prevention device as described in claim 2, characterized in that the friction force is generated between the first support member, the second support member, and the interposed member by clamping the first support member and the second support member with a predetermined clamping force via the fastening means. The plurality of intermediate members are
A bridge fall prevention device as described in claim 1 or claim 5, characterized in that the first support member and the second support member are arranged consecutively or side by side at a predetermined interval in the longitudinal direction. The first support member has a base plate and a side plate provided in a longitudinal direction at an interval in a width direction perpendicular to the base plate,
the second support member includes a center plate provided in a longitudinal direction between the side plates, an end plate provided at an end of the center plate, and the shock absorbing member provided on the end plate,
A bridge fall prevention device as described in claim 1 or claim 2, wherein the hole of the fastening means that penetrates the side plates and the central plate is formed as a long hole in the longitudinal direction. The central plate is provided in a plurality of positions between the side plates in the width direction,
A bridge fall prevention device as described in claim 7, which cites claim 1 , wherein the intermediate member is arranged between the center plate and the side plate. A bridge fall prevention device according to any one of claims 1 to 8, characterized in that the friction force generation range of the friction force generating means is larger than the displacement range of the first support member and the second support member. the frictional force generating means comprises a first metal surface provided on a sliding surface of the first support member and made of a metal material different from that of the first support member, and a second metal surface provided on a sliding surface of the second support member and made of a metal material different from that of the second support member,
A bridge fall prevention device according to any one of claims 1 to 9, wherein the first metal surface and the second metal surface are formed from metal-based sliding materials having different component compositions.

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