JP2004036338A

JP2004036338A - Bridge falling preventive device

Info

Publication number: JP2004036338A
Application number: JP2002198252A
Authority: JP
Inventors: Tadashi Tsuchiya; 土屋　正; Yoichi Shudo; 首藤　洋一; Yuji Tokunaga; 徳永　祐二; Yasuo Shindo; 進藤　泰男; Kazushi Kono; 河野　一資; Atsushi Tsunoda; 角田　敦; Koichi Tsukamoto; 塚本　光一
Original assignee: Daiichi Giken Consultant Kk; KOHYEI TRADING CO Ltd; Du Pont Toray Co Ltd; Tokyo Seiko Rope Manufacturing Co Ltd
Current assignee: Daiichi Giken Consultant Kk; KOHYEI TRADING CO Ltd; Du Pont Toray Co Ltd; Tokyo Seiko Rope Manufacturing Co Ltd
Priority date: 2002-07-08
Filing date: 2002-07-08
Publication date: 2004-02-05

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a fear of hindrance of traffic or river stream under a bridge while effectively preventing the bridge from falling. <P>SOLUTION: Bracket (6) are fixed respectively to the underface of a bridge (3) and the side face of a bridge support (5), and a long body (7) is spread between both brackets (6). Intermediate support members (9) are attached to at least one of the bridge (3) and the bridge support (5). The middle of the long body (7) is supported by the support members. The supporting force of the member (9) is made weaker than the fracture strength of the long body (7). When the bridge (3) is about to move by a large stress, the long body (7) easily comes off the support member (9). <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は鉄道や道路などに設けられる橋梁の落下を防止する落橋防止装置に関し、さらに詳しくは、橋梁の落下を効果的に防止しながら、しかも橋梁下方の交通や河川の流れを阻害する惧れのない落橋防止装置に関する。
【０００２】
【従来の技術】
従来、橋梁の落下を防止する落橋防止装置には、例えば図４に示すように、橋梁（５１）と橋脚などの橋梁支承部（５２）との間に、チェーンやスチールワイヤなどの長尺体（５３）を配置し、この長尺体（５３）の一端を橋梁（５１）の橋桁や道路床板（５４）などの下面に固定し、他端を橋梁支承部（５２）の上部側面に固定したものがある。
上記の長尺体（５３）は、設置作業等の理由から一般に弛ませた状態に付設されることが多く、図４に示すように、長尺体（５３）の重量で下方へ湾曲して垂れ下がった状態に付設されることが多い。
【０００３】
【発明が解決しようとする課題】
上記の橋梁（５１）は、河川や道路を跨ぐために設けられることが多い。道路を跨ぐ場合、例えば図４の仮想線に示すように、下方の道路を通行する車両（５５）の上端が上記の長尺体（５３）に引っかかる惧れがあった。このため、橋梁下方を通行する車両の高さを、橋梁下面の高さよりも低く制限する必要があった。また、橋梁が河川を跨ぐ場合には、河川を通行する船舶や、増水時に流れる流木等が上記の長尺体に引っかかって、船舶の通行や河川の流れを阻害する惧れがあった。このことは、上記の長尺体（５３）を橋梁（５１）と橋梁支承部（５２）との間に直線状に付設した場合にも、この長尺体（５３）が橋梁下方の空間の一部を横断するため、依然として同様の問題を生じる惧れがある。
【０００４】
本発明は上記の問題点を解消し、橋梁の落下を効果的に防止しながら、しかも橋梁下方の交通や河川の流れを阻害する惧れのない、落橋防止装置を提供することを技術的課題とする。
【０００５】
【課題を解決するための手段】
本発明は上記課題を解決するため、例えば本発明の実施の形態を示す図１から図３に基づいて説明すると、落橋防止装置を次のように構成したものである。
即ち、橋梁（３）と橋梁支承部（５）との間に長尺体（７）を張設した落橋防止装置であって、上記の橋梁（３）と橋梁支承部（５）との少なくとも一方に中間支持部材（９）を付設し、この中間支持部材（９）に上記の長尺体（７）の中間部を、この長尺体（７）の破断強度よりも弱い支持力で支持したことを特徴とする。
【０００６】
【作用】
長尺体はその中間部が中間支持部材により支持されるので、平常時は橋梁と橋梁支承部とに沿った状態に配置される。一方、地震発生等により大きな応力が加わって橋梁が橋梁支承部からずれ動こうとすると、その応力により長尺体が引っ張られる。このとき、上記の中間支持部材による支持力は長尺体の破断強度よりも弱く、大きな応力を受けると中間支持部材が変形や破損を生じたり橋梁等から脱落したりして長尺体を支持できなくなる。この結果、長尺体は直線状となり、上記の応力がこの長尺体により効果的に受け止められる。
【０００７】
上記の中間支持部材は、長尺体の中間部を支持できるものであればよく、紐や針金、金具など、任意の材質や形状・構造の部材を用いることができるが、例えば長尺体の少なくとも大部分を覆うカバーケースで構成した場合には、大気や日光への曝露等による悪影響で長尺体が早期に劣化することが防止される。
【０００８】
上記の長尺体は、チェーンやスチールワイヤなどで構成してもよいが、高強度を有する繊維材料で形成した場合には、この長尺体を軽量にできるので、固定による橋梁等への負担が軽く済み、取付け作業も容易である。この繊維材料としては、比強度２００×１０^３ｍ以上、比弾性率３×１０^６ｍ以上の繊維材料が好ましい。ここで比強度や比弾性率は、ＡＳＴＭ　Ｄ−８８５に順じて測定した強度及び弾性率を繊維の比重で割った値である。比強度は高いほど好ましく、具体的にはアラミド繊維、全芳香族ポリエステル繊維、ＰＢＯ繊維などを挙げることができる。アラミド繊維としては、パラ系全芳香族ポリアミド繊維が好ましいが、メタ系或いは非芳香族化合物が少量共重合されていてもよい。全芳香族ポリエステル繊維も液晶性全芳香族ポリエステル繊維が好ましいが、少量の脂肪族化合物が共重合された液晶性繊維も使用できる。
【０００９】
上記の繊維材料で形成した長尺体の形態としては、ベルト、ロープなどが好ましいが、他の形態であってもよく、厚さ、幅、太さなどは用途とスケール等により決定され、特定の形状、寸法に限定されない。また、これらの長尺体は他の材料で被覆、含浸、接着、表面処理などの加工処理が施されていてもよい。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づき説明する。
図１と図２は本発明の第１実施形態を示し、図１は落橋防止装置を設けた橋梁の要部の説明図、図２は落橋防止装置を示し、図２（ａ）は落橋防止装置の概略構成図、図２（ｂ）は図２（ａ）のＢ−Ｂ線矢視拡大断面図である。
【００１１】
図１に示すように、この落橋防止装置（１）は、河川（２）に架けられた橋梁（３）を構成する道路床板（４）の下面と、この道路床板（４）を支承する河川の側壁（５）の上部とにそれぞれ固定されたブラケット（６）を備え、両ブラケット（６・６）間に亘って長尺体（７）が張設してある。
【００１２】
上記の長尺体（７）は、例えばアラミド繊維等の、比強度が２００×１０^３ｍ以上、比弾性率が３×１０^６ｍ以上の高強度を有する繊維材料でベルト状に織成され、両端を縫い合せることにより環状にしてある。
図１及び図２（ａ）に示すように、上記の環状ベルトは偏平化されて長尺体（７）を構成しており、その両折返し端が上記の各ブラケット（６）に付設された固定ピン（８）にそれぞれ挿通され、これにより長尺体（７）が両ブラケット（６・６）間に張設されている。
【００１３】
上記の道路床板（４）の下面と上記の側壁（５）とには、それぞれ中間支持具（９）が付設してある。上記の長尺体（７）はこの中間支持具（９）に中間部を支持されることで、上記の道路床板（４）や河川の側壁（５）に沿った状態に配置される。
【００１４】
図２（ｂ）に示すように、上記の中間支持具（９）は、例えば合成樹脂や金属などでフック状に形成してある。この中間支持具（９）は、長尺体（７）の破断強度よりも弱い応力で容易に変形や破損し、地震発生時などの大きな力が加わって橋梁が移動すると、長尺体（７）がこの中間支持具（９）から簡単に外れるように構成してある。
【００１５】
なお、この実施形態では上記の中間支持部材をフック状に形成したが、本発明に用いる中間支持部材は上記の長尺体の中間部を支持できるものであればよく、特定の形状に限定されない。また、この実施形態では上記の中間支持部材を橋梁と橋梁支承部にそれぞれ１個ずつ付設したが、本発明の上記の中間支持部材は１個のみ設けても良く、或いは３個以上設けてもよい。これらの付設位置は、上記の実施形態のように橋梁（３）の下面と橋梁支承部（５）の側面の両方に設けてもよく、或いはいずれか一方にのみ設けても良い。
【００１６】
次に、上記の落橋防止装置の作動について説明する。
平常時にあっては、上記の長尺体（７）は中間部が中間支持具（９）に支持されており、道路床板（４）と河川の側壁（５）とに沿った状態に配置される。このため、河川を通行する船舶や増水時の流木等がこの長尺体（７）に引っかかる惧れを大幅に低減でき、或いはその惧れを無くすことができる。
【００１７】
地震発生時などに大きな応力を受けて道路床板（４）が移動しようとすると、長尺体（７）にその応力が伝わって上記の中間支持具（９）から外れる。この結果、長尺体（７）は、図１の仮想線に示すように、前記の両ブラケット（６・６）間に直線状に張設された状態となる。これにより長尺体（７）は上記の大きな応力を確りと受け止めることができ、道路床板（４）等の橋梁（３）の落下を効果的に防止することができる。
【００１８】
図３は本発明の第２実施形態を示し、カバーケースからなる中間支持部材を用いた落橋防止装置である。
この第２実施形態では、第１実施形態と同様、２つのブラケット（６・６）間に環状ベルトからなる長尺体（７）が張設されいるが、第１実施形態とは異なって、両ブラケット（６・６）並びに上記の長尺体（７）を覆う状態に、薄い金属材料または合成樹脂材料からなる逆Ｌ字形のカバーケース（１０）が道路床板（４）と河川の側壁（５）に亘って固定してある。
【００１９】
上記の長尺体（７）は、図３に示すようにその中間部が上記のカバーケース（１０）内面の角部に支持され、これにより道路床板（４）と河川の側壁（５）に沿った状態に配置されている。即ち上記のカバーケース（１０）は中間支持部材（９）を構成している。
このカバーケース（１０）は、長尺体（７）の破断強度よりも弱い応力で、道路床板（４）や上記の側壁（５）から容易に外れるように構成してある。従って、地震発生時などに大きな応力を受けて道路床板（４）が移動しようとすると、上記の第１実施形態と同様に作動し、道路床板（４）の落下が効果的に防止される。
【００２０】
またこの第２実施形態では、長尺体（７）やブラケット（６）をカバーケース（１０）で覆っているので、大気や日光などから長尺体（７）等を保護でき、落橋防止装置（１）の耐久性を高めることができる。
【００２１】
上記の各実施形態では一方のブラケットを道路床板に固定したが、橋梁が橋桁を備える場合は、この橋桁に上記の一方のブラケットを固定しても良い。また、上記の他方のブラケットを河川の側壁に固定したが、橋梁が橋脚に支持されている場合は、この橋脚に上記の他方のブラケットが固定される。
なお、上記の実施形態では河川に架けた橋梁に適用する場合について説明したが、本発明の落橋防止装置は道路など河川以外に架けた橋梁に適用できることは言うまでもない。
【００２２】
【発明の効果】
本発明は上記のように構成され作用することから、次の効果を奏する。
【００２３】
（１）　長尺体は、その中間部が中間支持部材により支持されて、平常時は橋梁と橋梁支承部とに沿った状態に配置されることから、橋梁の下方を通行する車両や船舶等がこの長尺体に引っかかる惧れがなく、また、橋梁下方の河川を流れる流木等がこの長尺体に引っかかる惧れもない。従って、本発明の落橋防止装置は橋梁下方の交通や河川の流れを阻害する惧れがない。
【００２４】
（２）　しかも、地震発生時など大きな応力を受けた場合には、長尺体が中間支持部材から外れるなどして直線状となり、上記の応力をこの直線状となった長尺体で受け止めるので、橋梁の落下を効果的に防止することができる。
【００２５】
（３）　上記の中間支持部材を、長尺体の少なくとも大部分を覆うカバーケースで構成した場合には、長尺体を大気や日光などによる悪影響から保護でき、長尺体の耐久性を高めることができる。
【００２６】
（４）　上記の長尺体を、高強度を有する繊維材料で形成した場合には、この長尺体を軽量にできるので、固定による橋梁等への負担を軽くでき、取付け作業も容易であるので、より好ましい。
【図面の簡単な説明】
【図１】本発明の落橋防止装置を設けた橋梁の要部の説明図である。
【図２】本発明の落橋防止装置の第１実施形態を示し、図２（ａ）は落橋防止装置の概略構成図、図２（ｂ）は図２（ａ）のＢ−Ｂ線矢視拡大断面図である。
【図３】本発明の第２実施形態を示す、図２（ａ）相当図である。
【図４】従来技術を示す、落橋防止装置を設けた橋梁の要部の説明図である。
【符号の説明】
１…落橋防止装置
３…橋梁
５…橋梁支承部（河川の側壁）
７…長尺体
９…中間支持部材（中間支持具）
１０…カバーケース[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fall prevention device for preventing a bridge from being dropped on a railway or a road, and more particularly, to a device that effectively prevents a bridge from falling and hinders traffic or river flow under the bridge. The present invention relates to a bridge prevention device without a bridge.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as shown in FIG. 4, for example, a long bridge such as a chain or a steel wire is provided between a bridge (51) and a bridge support (52) such as a pier as shown in FIG. (53) is arranged, one end of the long body (53) is fixed to the lower surface of a bridge girder or a road floor plate (54) of the bridge (51), and the other end is fixed to the upper side surface of the bridge support (52). There is something.
The above-mentioned elongated body (53) is often attached in a loose state for reasons of installation work and the like, and as shown in FIG. 4, it is bent downward by the weight of the elongated body (53). Often attached to a hanging state.
[0003]
[Problems to be solved by the invention]
The bridge (51) is often provided to cross a river or a road. When crossing a road, for example, as shown by a virtual line in FIG. 4, the upper end of the vehicle (55) passing through a lower road may be caught by the elongated body (53). For this reason, it was necessary to restrict the height of vehicles passing under the bridge to be lower than the height of the lower surface of the bridge. Further, when the bridge straddles a river, there is a concern that a ship passing through the river, a driftwood flowing at the time of rising of water, etc. may be caught by the long body, thereby obstructing the passage of the ship and the flow of the river. This means that even when the long body (53) is linearly provided between the bridge (51) and the bridge support part (52), the long body (53) can be installed in the space below the bridge. Crossing a part may still cause similar problems.
[0004]
It is a technical object of the present invention to solve the above problems and to provide a device for preventing a bridge from falling while effectively preventing the falling of the bridge and without obstructing the traffic under the bridge and the flow of a river. And
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention will be described with reference to, for example, FIGS. 1 to 3 showing an embodiment of the present invention.
That is, a fall prevention device in which a long body (7) is stretched between a bridge (3) and a bridge support (5), wherein at least the bridge (3) and the bridge support (5) are connected to each other. On one side, an intermediate support member (9) is attached, and the intermediate support member (9) supports the intermediate portion of the elongated body (7) with a supporting force weaker than the breaking strength of the elongated body (7). It is characterized by having done.
[0006]
[Action]
Since the middle part of the long body is supported by the middle support member, the long body is normally arranged along the bridge and the bridge support part. On the other hand, when a large stress is applied due to the occurrence of an earthquake or the like and the bridge tries to move from the bridge support portion and move, the elongated body is pulled by the stress. At this time, the supporting force of the intermediate support member is weaker than the breaking strength of the elongated body, and when a large stress is applied, the intermediate support member deforms or breaks or falls off the bridge or the like to support the elongated body. become unable. As a result, the elongated body becomes linear, and the above-mentioned stress is effectively received by the elongated body.
[0007]
The intermediate support member may be any member that can support the intermediate portion of the elongated body, and may be a member of any material, shape, or structure, such as a string, a wire, or a metal fitting. In the case where the cover is formed of a cover case that covers at least a large part, it is possible to prevent the long body from being deteriorated early due to an adverse effect due to exposure to the atmosphere or sunlight.
[0008]
The elongated body may be made of a chain, a steel wire, or the like. However, if the elongated body is formed of a fiber material having high strength, the elongated body can be reduced in weight, so that the load on a bridge or the like due to fixing is increased. However, the mounting work is easy. As the fiber material, a fiber material having a specific strength of 200 × 10 ³ m or more and a specific elastic modulus of 3 × 10 ⁶ m or more is preferable. Here, the specific strength and specific elastic modulus are values obtained by dividing the strength and elastic modulus measured according to ASTM D-885 by the specific gravity of the fiber. The higher the specific strength, the more preferable. Specific examples include aramid fiber, wholly aromatic polyester fiber, and PBO fiber. As the aramid fiber, a para-based wholly aromatic polyamide fiber is preferable, but a meta- or non-aromatic compound may be copolymerized in a small amount. The wholly aromatic polyester fiber is preferably a liquid crystalline wholly aromatic polyester fiber, but a liquid crystalline fiber obtained by copolymerizing a small amount of an aliphatic compound can also be used.
[0009]
The form of the long body formed of the above fiber material is preferably a belt, a rope, or the like, but may be another form, and the thickness, width, thickness, and the like are determined by the application and scale, and are specified. It is not limited to the shape and the size of. In addition, these elongated bodies may be subjected to processing such as coating, impregnation, adhesion, and surface treatment with another material.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a first embodiment of the present invention. FIG. 1 is an explanatory view of a main part of a bridge provided with a bridge prevention device, FIG. 2 shows a bridge prevention device, and FIG. FIG. 2B is a schematic configuration diagram of the device, and FIG. 2B is an enlarged cross-sectional view taken along line BB of FIG. 2A.
[0011]
As shown in FIG. 1, the fall prevention device (1) includes a lower surface of a road floor plate (4) constituting a bridge (3) bridged over a river (2) and a river supporting the road floor plate (4). And a bracket (6) fixed to the upper part of the side wall (5) of each of the above, and an elongated body (7) is stretched between both brackets (6.6).
[0012]
The long body (7) is woven in a belt shape with a high-strength fiber material such as aramid fiber having a specific strength of 200 × 10 ³ m or more and a specific elastic modulus of 3 × 10 ⁶ m or more. The both ends are sewn to form an annular shape.
As shown in FIGS. 1 and 2 (a), the above-mentioned annular belt is flattened to form a long body (7), and both folded ends are attached to the above-mentioned brackets (6). Each of the fixing pins (8) is inserted, whereby the elongated body (7) is stretched between the two brackets (6.6).
[0013]
An intermediate support (9) is attached to the lower surface of the road floor plate (4) and the side wall (5), respectively. The elongate body (7) is arranged along the road floor plate (4) and the side wall (5) of the river by supporting the intermediate portion by the intermediate support (9).
[0014]
As shown in FIG. 2 (b), the intermediate support (9) is formed in a hook shape using, for example, synthetic resin or metal. The intermediate support (9) is easily deformed or damaged by a stress weaker than the breaking strength of the elongated body (7), and when the bridge moves due to a large force applied at the time of an earthquake or the like, the elongated body (7). ) Is easily detached from the intermediate support (9).
[0015]
In this embodiment, the intermediate support member is formed in a hook shape, but the intermediate support member used in the present invention is not limited to a specific shape as long as it can support the intermediate portion of the elongated body. . Further, in this embodiment, the above-mentioned intermediate support member is attached to each of the bridge and the bridge support portion, but one of the above-mentioned intermediate support members of the present invention may be provided, or three or more intermediate support members may be provided. Good. These attachment positions may be provided on both the lower surface of the bridge (3) and the side surface of the bridge support (5) as in the above-described embodiment, or may be provided only on one of them.
[0016]
Next, the operation of the above-described bridge-fall prevention device will be described.
In normal times, the elongated body (7) has an intermediate portion supported by an intermediate support (9) and is arranged along the road floor plate (4) and the side wall (5) of the river. You. Therefore, it is possible to greatly reduce or eliminate the fear that a ship passing through a river or driftwood at the time of increasing the water catches on the long body (7).
[0017]
When the road floor plate (4) tries to move under a large stress such as when an earthquake occurs, the stress is transmitted to the elongated body (7) and the road floor plate (4) comes off the intermediate support (9). As a result, as shown by the imaginary line in FIG. 1, the elongated body (7) is in a state of being linearly stretched between the brackets (6.6). Thus, the long body (7) can reliably receive the above-mentioned large stress, and can effectively prevent the bridge (3) such as the road floor plate (4) from falling.
[0018]
FIG. 3 shows a second embodiment of the present invention, which is a bridge fall prevention device using an intermediate support member composed of a cover case.
In the second embodiment, as in the first embodiment, a long body (7) made of an annular belt is stretched between two brackets (6.6), but unlike the first embodiment, An inverted L-shaped cover case (10) made of a thin metal material or a synthetic resin material is provided so as to cover the brackets (6.6) and the elongated body (7). It is fixed over 5).
[0019]
As shown in FIG. 3, the elongated body (7) has an intermediate portion supported by a corner of the inner surface of the cover case (10), whereby the road floor plate (4) and the side wall (5) of the river are formed. It is arranged along the state. That is, the cover case (10) forms an intermediate support member (9).
The cover case (10) is configured to be easily detached from the road floor plate (4) and the side wall (5) with a stress lower than the breaking strength of the elongated body (7). Therefore, when a large stress is applied to the road floor plate (4) to move when an earthquake occurs, the operation is performed in the same manner as in the first embodiment, and the road floor plate (4) is effectively prevented from falling.
[0020]
Further, in the second embodiment, since the elongated body (7) and the bracket (6) are covered with the cover case (10), the elongated body (7) and the like can be protected from the atmosphere, sunlight, and the like. The durability of (1) can be improved.
[0021]
In the above embodiments, one bracket is fixed to the road floor plate. However, when the bridge includes a bridge girder, the one bracket may be fixed to this bridge girder. Further, the other bracket is fixed to the side wall of the river, but when the bridge is supported by a pier, the other bracket is fixed to the pier.
In the above embodiment, the case where the present invention is applied to a bridge over a river has been described. However, it goes without saying that the bridge fall prevention device of the present invention can be applied to a bridge over a river such as a road.
[0022]
【The invention's effect】
The present invention is configured and operated as described above, and has the following effects.
[0023]
(1) Since the intermediate portion of the long body is supported by the intermediate support member and is normally arranged along the bridge and the bridge support portion, vehicles, ships, and the like passing below the bridge are used. However, there is no fear that the long body will be caught by the long body, and there is no fear that driftwood or the like flowing through the river below the bridge will be caught by the long body. Therefore, the bridge fall prevention device of the present invention does not have a risk of hindering the traffic under the bridge and the flow of the river.
[0024]
(2) In addition, when a large stress is applied, such as at the time of an earthquake, the long body comes off the intermediate support member and becomes linear, and the above-mentioned stress is received by this linear body. The bridge can be effectively prevented from falling.
[0025]
(3) When the intermediate support member is formed of a cover case that covers at least most of the elongated body, the elongated body can be protected from the adverse effects of the atmosphere, sunlight, and the like, and the durability of the elongated body is increased. be able to.
[0026]
(4) When the long body is formed of a fiber material having high strength, the long body can be reduced in weight, so that a load on a bridge or the like due to fixation can be reduced, and the mounting work is also easy. Therefore, it is more preferable.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a main part of a bridge provided with a bridge fall prevention device of the present invention.
2A and 2B show a first embodiment of a bridge prevention device of the present invention, wherein FIG. 2A is a schematic configuration diagram of the bridge prevention device, and FIG. 2B is a view taken along line BB of FIG. 2A. It is an expanded sectional view.
FIG. 3 is a view showing a second embodiment of the present invention and corresponding to FIG. 2 (a).
FIG. 4 is an explanatory view of a main part of a bridge provided with a fall prevention device, showing a conventional technique.
[Explanation of symbols]
1 ... bridge fall prevention device 3 ... bridge 5 ... bridge bearing part (side wall of river)
7 ... Long body 9 ... Intermediate support member (intermediate support tool)
10 ... Cover case

Claims

A fall prevention device comprising a long body (7) stretched between a bridge (3) and a bridge support (5),
An intermediate support member (9) is attached to at least one of the bridge (3) and the bridge support (5),
A bridge fall prevention device, wherein an intermediate portion of the elongated body (7) is supported by the intermediate support member (9) with a supporting force weaker than the breaking strength of the elongated body (7).

The fall prevention device according to claim 1, wherein the intermediate support member (9) is constituted by a cover case (10) that covers at least most of the elongated body (7).

The fall prevention device according to claim 1 or 2, wherein the elongated body (7) is formed of a fiber material having high strength.

The fall prevention device according to claim 3, wherein the elongated body (7) is made of a fiber material having a specific strength of 200 × 10 ³ m or more and a specific elastic modulus of 3 × 10 ⁶ m or more.

The fall prevention device according to claim 4, wherein the fiber material is an aramid fiber.