JP7141588B2 - Bridge fall prevention device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bridge fall prevention device for preventing a bridge girder from falling.

A bridge is provided with a bridge fall prevention device to prevent a bridge girder from falling from a substructure due to a large shaking caused by an earthquake or the like. The bridge fall prevention device is provided so as to link the bridge girders together or the bridge girders and the substructure.

For example, Patent Document 1 discloses a tubular member having one end fixed to a bridge structure (for example, a bridge girder) and the other end fixed to another bridge structure (for example, an abutment), and a tubular member inserted into the tubular member. A bridge fall protection device is disclosed that includes a connecting line that is longer than a tubular member. The tubular member is axially stretchable. A wire rope, for example, is used as the connecting rope, and stoppers are formed at both ends of the connecting rope to be engaged with the ends of the tubular members.

When a seismic force acts on the bridge, the bridge fall prevention device follows the movement of the bridge structure by expanding and contracting the tubular member. When a large seismic force acts on the bridge and the bridge structure moves greatly, the stopper of the connecting rope is locked to the end of the tubular member, and the connecting rope separates the bridge structures from each other. distance is controlled. In this way, a bridge equipped with a bridge fall prevention device prevents the bridge girder from falling from the abutment even when a large seismic force acts on the bridge.

JP 2014-231721 A

Although such a bridge collapse prevention device uses a wire rope having a yield strength equal to or greater than the design seismic force, the upper limit of the yield strength of the wire rope is generally not considered. Therefore, when an unexpected force (a force that exceeds the design seismic force) acts on the bridge, the wire rope yield strength is greater than the yield strength of the bridge structure (mounting part), so the bridge fall prevention device will not be installed before the bridge collapse prevention device. There is a risk of damage to the bridge structure. When a bridge structure is damaged, it takes time and money to restore it.

From this point of view, it is an object of the present invention to propose a bridge fall prevention device that does not cause damage to a bridge structure even when an unexpected seismic force acts.

The bridge fall prevention device of the present invention for solving the above problems comprises a first fixing member fixed to a bridge girder which is a bridge structure, and a second fixing member fixed to another bridge structure different from the bridge girder. , a bridge fall prevention device comprising a first wire rod inserted through the first fixing member, a second wire rod inserted through the second fixing member, and a connecting member connecting the first wire rod and the second wire rod is. The first wire rod and the second wire rod can be locked to the first fixing member or the second fixing member at the ends opposite to the connecting member. Further, the yield point or proof stress of the connecting member is equal to or higher than the design seismic force, and the upper limit of the tensile strength of the connecting member is known. Furthermore, the upper limit value of the tensile strength is smaller than the yield strength of the attachment portion between the first fixing member and the bridge girder and the yield strength of the attachment portion between the second fixing member and the other bridge structure.

According to this bridge fall prevention device, since the tensile strength of the connecting member is known, the strength of the mounting portion of the bridge fall prevention device of the bridge structure (bridge girder, abutment, bridge pier, etc.) is set to be greater than the strength of the bridge fall prevention device. be able to. Therefore, when an unexpected seismic force acts on the bridge, it is possible to prevent the bridge structure from being damaged by breaking the connecting member first. By minimizing damage to bridge structures, it is possible to save labor in bridge restoration work, and as a result, bridge services can be resumed early.

If the connecting member is a plate material having through holes formed at both ends thereof and is joined to the first wire rod and the second wire rod by bolts or pins, respectively, the connecting member can be easily replaced. In addition, since the connecting member and each wire rod (first wire rod or second wire rod) are rotatably joined, vibration in the direction crossing the axial direction of each wire rod (first wire rod or second wire rod) is absorbed. becomes possible.

Further, if the width of the connecting member is reduced at the intermediate portion between the through holes, the connecting member will break at a predetermined position due to a predetermined tensile force. Therefore, when an unexpected seismic force acts, the connecting member is reliably broken, and the burden on the bridge structure can be minimized.

In addition, when an eye end sleeve is formed at the ends of the connecting member side of the first wire and the second wire, the eye end sleeve is sandwiched between the two connecting members by bolting or pinning. It should be joined. Further, when a fork end sleeve is formed at the ends of the first wire and the second wire on the side of the connecting member, bolting or pinning with the connecting member inserted into the fork end sleeve good. Furthermore, when screw ends are formed at the ends of the first wire rod and the second wire rod on the side of the connecting member, they may be joined to the connecting member having a male thread via a high bolt or the like. .

The connecting member may be a grip end fixed to the end of the connecting member side of the first wire and the second wire or a connecting member locked to a nut, or the first wire and the second wire. It may be joined to a connection member that is screwed into a screw end formed at the end of the wire on the side of the connection member.

If the first fixing member and the second fixing member have an outer pipe fixed to the bridge structure and an inner pipe slidably inserted into the outer pipe, the first fixing member And it becomes possible for the second fixing member to follow the movement of the bridge structure. At this time, the first wire is inserted through the inner tube of the first fixing member, and the second wire is inserted through the inner tube of the second fixing member.

According to the bridge collapse prevention device of the present invention, even if an unexpected seismic force acts, the bridge structure will not be damaged.

(a) A longitudinal sectional view showing a bridge fall prevention device according to an embodiment of the present invention, and (b) is a horizontal sectional view of the same. It is a figure which shows the joint part of a 1st wire or a 2nd wire, (a) is a side view, (b) is a top view. It is a figure which shows a connection member, (a) is a side view, (b) is a top view. It is a figure which shows the attachment condition of a connection member, (a) is a side view, (b) is a top view. It is an enlarged vertical cross-sectional view of the bridge fall prevention device. It is a figure which shows a bridge fall prevention device when the seismic load below design seismic force acts on a bridge. It is a figure which shows the bridge fall prevention apparatus after bearing destruction. It is a figure which shows a bridge fall prevention device after a connection member fracture|ruptures. It is a figure which shows the connection member which concerns on another form. It is a figure which shows the junction part of the 1st wire which concerns on another form, or a 2nd wire, (a) is a side view, (b) is a top view. It is a figure which shows the attachment condition of the connection member which concerns on another form, Comprising: (a) is a side view, (b) is a top view. It is a figure which shows the connection member of the 1st wire which concerns on another form, and a 2nd wire, (a) is a perspective view, (b) is an exploded perspective view. 13(a) to 13(c) are cross-sectional views showing connecting members of the first wire rod or the second wire rod shown in FIG. 12. FIG.

In this embodiment, a bridge fall prevention device 1 for preventing a bridge girder B1 of a bridge B from falling will be described. As shown in FIG. 1(a), the bridge fall prevention device 1 connects two bridge girders B1, B1 that are connected to the top of a bridge pier B2. The bridge fall prevention device 1 may connect the bridge girder B1 and the bridge abutment or the bridge girder B1 and the bridge pier B2, and is not limited to connecting the bridge girder B1 to each other.

The bridge girder B1 spans between the adjacent bridge piers B2 or between the bridge pier B2 and the abutment. The bridge girder B1 is mounted on the bridge pier B2 via the bearing S. In this embodiment, a rubber bearing is employed as the bearing S, but the configuration of the bearing S is not limited, and may be, for example, a slide bearing. A gap is formed between adjacent bridge girders B1, B1. Since the gap is formed between the bridge girders B1, contact with each other is prevented when the bridge girders B1 move due to vibration or the like.

As shown in FIGS. 1(a) and 1(b), the bridge fall prevention device 1 includes a first wire rod 2, a second wire rod 3, a connecting member 4, a first fixing member 5 and a second fixing member 6. there is

The first wire rod 2 is inserted through the first fixing member 5 . That is, the first wire rod 2 is attached to the bridge girder B1 via the first fixing member 5 . The first wire rod 2 is composed of a galvanized wire rope. Note that the wire rope forming the first wire rod 2 does not necessarily have to be galvanized. Moreover, the material constituting the first wire rod 2 is not limited, and for example, a steel bar or the like may be used.

A joint portion 21 for attaching the connecting member 4 is formed at one end of the first wire rod 2 (the end on the connecting member 4 side). As shown in FIGS. 2A and 2B, the joint 21 of this embodiment is a so-called eye-end sleeve formed with a through hole 22 through which a bolt can be inserted.

A locking portion 23 is formed at the other end of the first wire rod 2 (the end opposite to the connecting member 4). The locking portion 23 of the present embodiment is a tubular member having an outer shape larger than the inner diameter of an insertion hole of a locking plate 53 of the first fixing member 5 described later, and is fixed to the end of the first wire rod 2. formed by That is, the locking portion 23 has a shape that can be locked to the first fixing member 5 (locking plate 53). The configuration of the locking portion 23 is not limited, and may be, for example, a plate member fixed to the end of the first wire 2 or a nut screwed to the end of the first wire 2. .

The second wire rod 3 is inserted through the second fixing member 6 as shown in FIGS. 1(a) and 1(b). That is, the second wire 3 is attached to the other bridge girder B1 via the second fixing member 6 . The second wire rod 3 does not necessarily have to be attached to the bridge girder B1, and may be attached to the abutment or the pier B2, for example. The second wire rod 3, like the first wire rod 2, is made of a galvanized wire rope. In addition, the material constituting the second wire rod 3 is not limited, and for example, a steel bar or the like may be used.

A joint portion 31 for attaching the connecting member 4 is formed at one end of the second wire rod 3 (the end on the connecting member 4 side). The joint portion 31 of the present embodiment is a so-called eye end sleeve formed with a through hole 32 through which a bolt can be inserted (see FIGS. 2(a) and 2(b)). Note that the shape of the joint portion 31 is not limited.

A locking portion 33 is formed at the other end of the second wire rod 3 (the end opposite to the connecting member 4 ). The locking portion 33 has a shape that can be locked to the second fixing member 6 (locking plate 63). The details of the locking portion 33 of the second wire rod 3 are the same as those of the locking portion 23 of the first wire rod 2, so detailed description thereof will be omitted.

The connecting member 4 connects the first wire rod 2 and the second wire rod 3, as shown in FIGS. 1(a) and 1(b). As shown in FIG. 4(a), the connecting member 4 is an oval plate material made of low yield point steel. That is, the connecting member 4 has a known upper limit of tensile strength. In addition, the material constituting the connecting member 4 is not limited as long as the upper limit value of the tensile strength is known, and does not necessarily have to be low yield point steel. In this embodiment, as shown in FIG. 4(b), two connecting members 4, 4 are arranged. In addition, the number of sheets of the connection member 4 is not limited.

Through holes 41 for inserting bolts are formed at both ends of the connecting member 4 . As shown in FIGS. 3A and 3B, a ring-shaped step is formed around the through hole 41 to increase the plate thickness. It should be noted that the step around the through hole 41 does not necessarily have to be formed, and may be flat. The width of the connecting member 4 is reduced from the through hole 41 toward the center. In addition, notches 42 are formed on both sides of the longitudinal intermediate portion of the connecting member 4 (intermediate portion between the through holes 41). Note that the notch 42 may be formed as required, and may be omitted. Moreover, the shape of the connecting member 4 is not limited, and for example, the width may be constant.

The total yield point or proof stress of the connecting members 4, 4 connecting the first wire rod 2 and the second wire rod 3 is greater than or equal to the design seismic force. When the first wire rod 2 and the second wire rod 3 are connected by one connecting member 4, the yield point or proof stress of the one connecting member 4 is made equal to or greater than the design seismic force. The mounting portion of the bridge fall prevention device 1 (such as the horizontal girder of the bridge girder B1) is the total tensile strength of the connecting members 4, 4 (if there is one connecting member 4, the tensile strength of one connecting member 4). It is necessary to ensure greater durability. In the present embodiment, the transverse girder has a larger cross-sectional dimension than the connecting member 4, by increasing the cross-sectional dimension of the concrete. The tensile strength of the connecting member 4 can be calculated from the tensile strength of the material that constitutes the connecting member 4 and the cross-sectional area of the position (on the line connecting the notches 42) that breaks when an unexpected seismic force acts. can. The structure of the mounting portion may be appropriately determined according to the structure of the bridge structure (bridge girder B1), and may be a steel structure, for example. Moreover, the concrete slab may be formed as needed.

One end of the connecting member 4 is bolted to the joint 21 of the first wire 2 , and the other end of the connecting member 4 is bolted to the joint 31 of the second wire 3 . In this embodiment, a pair of connecting members 4, 4 are arranged so as to sandwich the joints 21, 31 from above and below, and a nut is attached to a bolt passing through the connecting members 4, 4 and the joints 21, 31. screw together. In addition, the connection member 4 is not limited to the bolt connection, and may be, for example, a pin connection. Moreover, in FIG. 4, the plate surface of the connecting member 4 is arranged vertically, but the direction of the connecting member 4 is not limited, and for example, the plate surface of the connecting member 4 may be arranged horizontally.

The connecting member 4 is covered with a protective cover 43 . Both ends of the protective cover 43 are fixed to the first fixing member 5 (inner tube 52) and the second fixing member 6 (inner tube 62). The protective cover 43 is desirably made of a flexible and stretchable material (for example, a polyethylene bellows tube or the like) so that it can follow the movement of the bridge girder B1. In addition, the protective cover 43 only needs to cover the connecting member 4, and the material forming the connecting member 4, the shape of the connecting member 4, and the like are not limited. Moreover, the protective cover 43 does not contribute as a resistance member against seismic force.

The first fixing member 5 is fixed to one (left side in FIG. 1) bridge girder B1. As shown in FIG. 5, the first fixing member 5 includes an outer pipe 51 embedded in the horizontal girder (winding concrete) of the bridge girder B1, an inner pipe 52 slidably inserted into the outer pipe 51, It has a locking plate 53 provided at the end of the outer tube 51 and a cushioning material 54 interposed between the outer tube 51 and the locking plate 53 . Note that the configuration of the first fixing member 5 is not limited.

The outer tube 51 forms an insertion hole through which the first wire rod 2 is inserted in the horizontal girder of the bridge girder B1.
The inner tube 52 has flexibility, and a portion thereof is inserted into the outer tube 51 and the remaining portion protrudes from the outer tube 51 toward the connecting member 4 . The first wire 2 is inserted through the inner tube 52 .

The locking plate 53 is a steel plate having an insertion hole through which the first wire 2 is inserted. The inner diameter of the insertion hole of the locking plate 53 is larger than the outer diameter of the first wire 2 and smaller than the width (outer diameter) of the locking portion 23 . Therefore, the locking plate 53 formed at the end of the outer tube 51 can lock the locking portion 23 . Note that the material forming the locking plate 53 is not limited as long as it has a predetermined strength, and does not necessarily have to be a steel plate.

The cushioning material 54 is a plate material made of resin (for example, a rubber plate) and has an area larger than that of the locking plate 53 . The cushioning material 54 is in contact with the side surface of the mounting portion (horizontal beam). A holding plate 55 made of a steel plate having the same area as the cushioning material 54 is interposed between the cushioning material 54 and the locking plate 53 . The cushioning material 54 absorbs the shock when the locking portion 23 contacts the locking plate 53 with its elastic force. Note that the impact force when the locking portion 23 contacts the locking plate 53 is dispersed by the restraining plate 55 and acts on the entire surface of the cushioning material 54 .

The end of the first fixing member 5 opposite to the connecting member 4 is covered with a cover material 56 . The cover member 56 includes a cylindrical portion 56 a into which the first wire 2 is inserted, and a plate portion 56 b that covers the outer surface of the locking plate 53 . The cylindrical portion 56 a has an inner diameter larger than the outer diameter of the locking portion 23 . Further, when the bridge girder B1 moves during an earthquake or the like, the tip of the tubular portion 56a and the end face of the locking portion 23 are arranged so that the first wire rod 2 can slide inside the tubular portion 56a. A gap of a predetermined length is secured between them.

As shown in FIG. 1, the second fixing member 6 is fixed to the other (right side in the drawing) bridge girder B1. In addition, the second fixing member 6 does not necessarily have to be fixed to the bridge girder B1, and may be fixed to the bridge pier B2 or the abutment, for example. As shown in FIG. 5, the second fixing member 6 includes an outer pipe 61 embedded in the horizontal girder (winding concrete) of the bridge girder B1, an inner pipe 62 slidably inserted into the outer pipe 61, A locking plate 63 provided at the end of the outer tube 61 and a cushioning material 64 interposed between the outer tube 61 and the locking plate 63 are provided.

The outer tube 61 forms an insertion hole through which the second wire rod 3 is inserted in the horizontal girder of the bridge girder B1.
The inner tube 62 has flexibility, and a portion thereof is inserted into the outer tube 61 and the remaining portion protrudes from the outer tube 61 toward the connecting member 4 . The second wire rod 3 is inserted through the inner tube 62 .

The locking plate 63 is a steel plate having an insertion hole through which the second wire 3 is inserted. The inner diameter of the insertion hole of the locking plate 63 is larger than the outer diameter of the second wire 3 and smaller than the width (outer diameter) of the locking portion 33 . Therefore, the locking plate 63 formed at the end of the outer tube 61 can lock the locking portion 33 . Note that the material forming the locking plate 63 is not limited as long as it has a predetermined strength, and does not necessarily have to be a steel plate.

The cushioning material 64 is a plate material made of resin (for example, a rubber plate) and has an area larger than that of the locking plate 63 . The cushioning material 64 is in contact with the side surface of the mounting portion (horizontal beam). A holding plate 65 made of a steel plate having the same area as the buffer material 64 is interposed between the buffer material 64 and the locking plate 63 . The cushioning material 64 absorbs impact when the locking portion 33 contacts the locking plate 63 . Note that the impact force when the locking portion 33 contacts the locking plate 63 is dispersed by the restraining plate 65 and acts on the entire surface of the cushioning material 64 .

The end of the second fixing member 6 opposite to the connecting member 4 is covered with a cover material 66 . The cover material 66 includes a cylindrical portion 66a into which the second wire rod 3 is inserted and a plate-like portion 66b that covers the locking plate 63. As shown in FIG. The cylindrical portion 66 a has an inner diameter larger than the outer diameter of the locking portion 33 . Further, when the bridge girder B1 moves during an earthquake or the like, the tip of the tubular portion 66a and the end face of the locking portion 33 are arranged so that the second wire rod 3 can slide inside the tubular portion 66a. A gap of a predetermined length is secured between them.

When a seismic force less than the design seismic force acts on the bridge B, as shown in FIG. 6, the bearing S absorbs the shaking. Even when the bridge girders B1 are separated from each other, the first wire 2 and the second wire 3 slide against the first fixing member 5 and the second fixing member 6, respectively, and stress acts on the connecting member 4. never do.

As shown in FIG. 7, when a seismic force greater than or equal to the design seismic force (level 2 or higher) acts on the bridge B and the bearing S is damaged, the bridge girders B1 are connected to each other by the bridge fall prevention device 1. Therefore, the bridge girder B1 is prevented from falling from the bridge pier B2. At this time, the amount of movement of the bridge girder B1 is kept within the range of 75% of the initial value SE of the girder span length by the bridge fall prevention device 1 . It should be noted that setting the amount of movement of the bridge girder B1 to 75% of SE is in accordance with the Specifications for Highway Bridges (2017 version), and in the case of other regulations, that regulation may be followed.

When an earthquake force greater than the tensile strength of the connecting member 4 acts on the bridge B, the connecting member 4 breaks along the line connecting the notches 42, 42 as shown in FIG. Breakage of the connecting member 4 prevents the mounting portion of the bridge fall prevention device 1 (the horizontal beam of the bridge girder B1) from being damaged. In addition, since the amount of movement of the bridge girder B1 is kept within the range of 75% of the girder span length SE due to the operation of the bridge fall prevention device 1, even if the connecting member 4 breaks, the bridge girder B1 falls. A digit overhang length (0.25 SE) is secured to the extent that it does not occur. Here, the design seismic force may be, for example, 1.5 times (1.5R _d ) the dead load reaction force of the substructure supporting the bridge girder B1. In addition, the above-mentioned displacement (75% of SE), girder span length (0.25SE), design seismic force (1.5 times the dead load reaction force (1.5Rd)) are ), and if it is based on other regulations, that regulation should be followed.

As described above, according to the bridge fall prevention device 1, since the tensile strength of the connecting member 4 is known, the strength of the mounting portion of the bridge fall prevention device 1 of the bridge structure (bridge girder B1, abutment, pier B2, etc.) is It can be made equal to or greater than the yield strength of the device 1 . Therefore, when an unexpected seismic force acts on the bridge B, the connecting member 4 breaks first, thereby preventing the bridge structure from being damaged.
Further, even if the connecting member 4 is broken, the connecting member 4 can be easily replaced.

Moreover, since the notch 42 is formed in the intermediate portion (the width is reduced), the connecting member 4 can be broken at the intermediate portion (predetermined position). Therefore, by calculating the tensile strength of the connecting member 4 , the strength of the mounting portion can be reliably made greater than the tensile strength of the connecting member 4 .

In addition, since the connecting member 4 is bolted or pinned to the first wire rod 2 and the second wire rod 3 respectively, replacement is easy. In addition, if the connecting member 4 is joined with bolts or pins, the connecting member 4 can rotate around the bolt or pin, so that the first wire rod 2 or the second wire rod 3 is prevented from swinging in the direction crossing the axial direction. can be absorbed.

Since the first wire 2, the second wire 3 and the connecting member 4 are covered with the inner pipes 52, 62, the cover members 56, 66 and the protective cover 43, they are protected against deterioration due to ultraviolet rays and rainwater. there is In addition, since the inner pipes 52 and 62 and the connecting member 4 are flexible, even if the first wire rod 2 or the second wire rod 3 is shaken in the direction crossing the axial direction, the coating protection is maintained.

Since cushioning materials 54, 64 are interposed between the locking plates 53, 63 and the horizontal beams of the bridge girder B1, the locking portions 23, 33 collide with the locking plates 53, 63 due to shaking caused by an earthquake or the like. Minimize impact force.

The embodiments according to the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and each of the above-described constituent elements can be modified as appropriate without departing from the gist of the present invention.
For example, in the above embodiment, the connecting member 4 is bolted or pinned to the first wire rod 2 and the second wire rod 3, but the mounting method of the connecting member 4 is not limited. For example, as shown in FIG. 9, male threads (screw ends) are formed at the ends of the connecting member 4, the first wire 2 and the second wire 3, and the male threads are screwed into the high nut 44. The connecting member 4 and the first wire 2 or the second wire 3 may be connected.

In the above embodiment, the joint 21 of the first wire 2 and the joint 31 of the second wire 3 are eye end sleeves, but the shapes of the joints 21 and 31 are not limited. For example, as shown in FIGS. 10(a) and 10(b), it may be a U-shaped so-called fork end sleeve. When the joints 21 and 31 are fork end sleeves, as shown in FIGS. With the ends inserted, the first wire rod 2 and the second wire rod 3 are attached by screwing the high nut 44 onto the bolt through which the joints 21 and 31 and the connecting member 4 are inserted.

Alternatively, the connecting member 4 may be attached to the first wire 2 and the second wire 3 via connecting members 24 and 34, as shown in FIG. 12(a). The connection members 24 and 34 are joint portions 21 and 31 formed at the ends of the first wire rod 2 and the second wire rod 3, respectively. As such connection members 24 and 34, as shown in FIG. 12(b), square prism-shaped hollow members may be used. In addition, the shape of the connection members 24 and 34 is not limited. Bolt holes 25 and 35 are formed in the connecting members 24 and 34 according to the positions of the through holes 41 of the connecting member 4, so that bolts inserted through the through holes 41 of the connecting member 4 can be screwed. It is Further, grooves 26, 36 corresponding to the shape of the connecting member 4 are formed in the connecting members 24, 34 as necessary. In this case, by inserting the connecting member 4 into the grooves 26, 36, the connecting member 4 and the connecting members 24, 34 are engaged.

The method of fixing the connection member 24 (34) to the first wire 2 (second wire 3) is not limited. For example, as shown in FIG. 13( a ), a connection member is attached to the end of the first wire 2 (second wire 3 ) inserted through the wire insertion hole 27 ( 37 ) formed in the connection member 24 ( 34 ). 24 (34) may be locked by fixing a grip end 71 having a width larger than the inner diameter of the wire rod insertion hole 27 (37). At this time, it is desirable to interpose a stop plate 72 between the grip end 71 and the inner wall surfaces of the connecting members 24 and 34 .

Moreover, as shown in FIG.13(b), the connection member 24 (34) may be fixed by screwing to the edge part of the 1st wire 2 (2nd wire 3). At this time, the inner surface of the wire insertion hole 27 (37) of the connection member 24 (34) is internally threaded, and the end of the first wire 2 (second wire 3) is externally threaded. .
Furthermore, as shown in FIG. 13(c), a nut is attached to the end of the first wire rod 2 (second wire rod 3) inserted through the wire rod insertion hole 27 (37) of the wire rod insertion hole of the connection member 24 (34). The first wire rod 2 (second wire rod 3) and the connection member 24 (34) may be fixed by screwing together.

1 bridge fall prevention device 2 first wire rod 21 joint portion 22 through hole 23 locking portion 3 second wire rod 31 joint portion 32 through hole 33 locking portion 4 connecting member 41 through hole 5 first fixing member 51 outer pipe 52 inner pipe 6 Second fixing member 61 outer tube 62 inner tube

Claims (8)

a first fixing member fixed to a bridge girder which is a bridge structure;
a second fixing member fixed to another bridge structure different from the bridge girder;
a first wire inserted through the first fixing member;
a second wire rod inserted through the second fixing member;
A bridge fall prevention device comprising a connecting member that connects the first wire and the second wire,
The first wire and the second wire can be locked to the first fixing member or the second fixing member at the ends opposite to the connecting member,
The yield point or proof stress of the connecting member is equal to or greater than the design seismic force and the upper limit of the tensile strength of the connecting member is known,
The upper limit value of the tensile strength is smaller than the yield strength of the attachment portion between the first fixing member and the bridge girder and the yield strength of the attachment portion between the second fixing member and the other bridge structure. , Bridge fall prevention device. 2. The falling bridge according to claim 1, wherein the connecting member is a plate member having through holes formed at both ends, and is bolted or pinned to the first wire rod and the second wire rod. prevention device. 3. The bridge fall prevention device according to claim 2, wherein the width of said connecting member is reduced at an intermediate portion between said through holes. 2. The bridge fall prevention device according to claim 1, wherein an eye end sleeve, a fork end sleeve, or a screw end is formed at the ends of the first wire rod and the second wire rod on the connecting member side. 4. The bridge collapsing prevention device according to claim 2, wherein the connecting member is joined to connecting members formed on the first wire and the second wire. A grip end or a nut is fixed to the ends of the first wire and the second wire on the connecting member side,
6. The bridge fall prevention device according to claim 5, wherein the connecting member is engaged with the grip end or the nut. screw ends are formed at ends of the first wire rod and the second wire rod on the connecting member side,
6. The bridge fall prevention device according to claim 5, wherein the connecting member is screwed onto the screw end. wherein the first fixing member and the second fixing member have an outer pipe fixed to the bridge structure and an inner pipe slidably inserted into the outer pipe;
The first wire is inserted through the inner tube of the first fixing member,
The bridge fall prevention device according to any one of claims 1 to 7, wherein the second wire is inserted through the inner pipe of the second fixing member.

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