JP2017155544A - Bridge fall prevention member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bridge fall prevention member which allows easy and quick inspection after an earthquake, and is easy to identify and exchange a damaged part in an earthquake.SOLUTION: A bridge fall prevention member connects a bridge upper structure body, such as a bridge girder H, and a bridge lower structure body, such as a bridge abutment B and a bridge pier, so as to prevent the fall of the bridge upper structure body. The bridge fall prevention member includes a connection member, such as a chain or a rope, which connects the bridge lower structure body and the bridge upper structure body. In a part of the connection member, a weaken portion 2 having a lower strength against an impact load in an earthquake than the remainder of the connection member is formed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a falling bridge prevention member for preventing a bridge girder from falling.

  In general bridges, bridge upper structures such as bridge girders and bridge substructures such as abutments and piers are not rigidly joined, but they are joined by roller bearings or pin bearings via bearing members. It has become a structure. For this reason, from the viewpoint of preventing major accidents involving human lives, the bridge upper structure is connected to the bridge lower structure with a fall prevention member such as a fall prevention chain that prevents the bridge upper structure from falling from the bridge lower structure. Has been.

  Conventionally, as this kind of fallen bridge prevention member, a buffer chain in which links are connected by interposing a buffer material such as rubber that absorbs an impact so as not to be broken by an impact load transmitted during an earthquake or the like has been proposed.

  For example, in Patent Document 1, the link 6 is embedded in the elastic body 7 in a state where the plurality of links 6 are arranged so as not to contact each other and are fitted to each other so that the links 6 are linearly aligned. One end of the buffer member 5 formed in a substantially rod shape by filling the gap with the elastic body 7 is fixed near the end of the beam 2 by the connecting member 11 and the fixing member 10, and the other end is fixed to the connecting member 9. A girder fall prevention structure is disclosed that is fixed to the end of the pier 1 or the adjacent girder 2A by the member 8 (claim 1 of the patent document 1 and paragraphs [0017] to [ 0022], see FIGS. 1 and 2 of the drawings).

  However, the girder dropping prevention structure described in Patent Document 1 has a shock-absorbing effect on the elastic body 7 such as rubber, but the elastic body 7 is overwhelmingly lower in strength than the link 6 and is therefore made of rubber. There was almost no difference in strength between the coated part and the non-coated part. Therefore, when there is a large-scale earthquake, it is unclear which part of the plurality of links 6 breaks. For this reason, if there is a large-scale earthquake, if you do not carefully check all parts of the girder fall prevention structure, you will not know whether it is damaged or not, and it will take time and effort to check after the earthquake There was a problem. In addition, when breaking, there is a possibility of breaking other than the buffer member 5, and there is a problem that there is a risk of a fall accident in which a broken metal piece falls on the lower bridge in a three-dimensionally intersecting bridge or the like .

  Further, in Patent Document 2, both ends of the abutment 1 and the bridge girder 2 are connected to each other, and a connecting member 11 having an expansion / contraction part 11 that can be partially expanded and contracted, and a metal in a state where the expansion / contraction part 11a is shortened. The sleeve 13 is provided with a shock absorbing mechanism having both ends fixed to the inner periphery of the metal sleeve 13, and the metal sleeve 13 is formed with a number of slits 15 extending in the circumferential direction at intervals in the axial direction. (See claim 1 of claim 2 of patent document 2, paragraphs [0009] to [0013] of the specification, FIG. 1 of FIG. 2, FIG. 2 etc.).

  However, although the falling bridge prevention device described in Patent Document 2 can absorb a part of impact energy by plastic deformation of the slit 15 of the metal sleeve 13, which part of the link chain 11 breaks. Could not be identified. For this reason, similarly to the girder fall prevention structure described in the above-mentioned Patent Document 1, it is not possible to solve the problem that the inspection after the earthquake takes time and effort and the risk of a fall accident. It was.

Japanese Patent Laid-Open No. 9-242019 JP 2010-53618 A

  Therefore, the present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to easily perform inspection after an earthquake in a short time and to easily identify and replace a damaged portion at the time of an earthquake. It is in providing a suitable fall bridge prevention member.

  A falling bridge prevention member according to a first aspect of the present invention is a falling bridge prevention member that connects a bridge upper structure such as a bridge girder and a bridge lower structure such as an abutment or a pier to prevent the bridge upper structure from falling. It is equipped with a connecting material such as a chain or rope that connects the lower structure and the bridge upper structure, and a weak point that is lower in strength against impact load during an earthquake than other parts is formed in a part of this connecting material. It is characterized by being.

  The fallen bridge prevention member according to a second aspect of the present invention is the first aspect of the present invention, wherein the connecting member is a chain in which a plurality of links made of steel are connected, and the weak point is smaller in diameter than the other part. The link material is low in tensile strength, or has a lower strength than other portions with respect to an impact load during an earthquake due to heat treatment.

  According to a third aspect of the present invention, there is provided the bridge-fall preventing member according to the second aspect, wherein after the heat treatment is applied to all or a part of the plurality of links of the connecting member, a plating layer such as hot dip galvanizing is formed. Features.

  The fallen bridge prevention member according to a fourth aspect of the present invention is characterized in that, in any one of the first to third aspects of the invention, the weak point portion is solidified with a rubber elastic body.

  The fallen bridge preventing member according to a fifth aspect of the present invention is characterized in that, in the fourth aspect, the weakened portion is solidified by the rubber elastic body after a rough surface treatment such as shot blasting is performed.

  The fallen bridge preventing member according to a sixth aspect of the invention is characterized in that, in the fourth or fifth aspect of the invention, the solidified rubber elastic body is provided with a mark capable of confirming plastic deformation.

  The fallen bridge preventing member according to a seventh aspect of the present invention is characterized in that, in the sixth aspect, the mark is a straight line or a straight dot.

  According to 1st invention-7th invention, since the weak point part with low intensity | strength is formed with respect to the impact load at the time of an earthquake, when a big impact load acts on a fallen bridge prevention member, the location broken is a weak point part It becomes. For this reason, it is possible to determine whether or not the fallen bridge prevention member should be replaced only by checking the weak point portion of the fallen bridge prevention member after a major earthquake, and the post-earthquake inspection can be easily performed in a short time. Moreover, it is only necessary to replace the weak point part, the replacement cost of the falling bridge prevention member can be reduced, and the life cycle cost can be reduced.

  In particular, according to the third invention, when plating is performed after heat treatment such as quenching and tempering, the toughness and strength of the steel material whose impact resistance and tensile strength are improved by the heat treatment occur. For this reason, according to the 3rd invention, not the conventional plating process but the part which was separately processed by the antirust coating can be subjected to the antirust process by the plating process at a time. For this reason, the time required for the anticorrosion coating can be reduced, and the production cost of the falling bridge prevention member can also be reduced.

  In particular, according to the fourth invention, since the periphery of the weak point portion is solidified by the rubber elastic body, there is no possibility that the broken link or the like is scattered around, and the risk of a fall accident in which the broken metal piece falls is eliminated. be able to. In addition, the shock load can be obtained by absorbing the impact load with the rubber elastic body.

  In particular, according to the fifth aspect, the weakened portion is solidified by the rubber elastic body after the rough surface treatment such as shot blasting is performed, so that not only the corrosion resistance of the falling bridge prevention member is improved, but also the rubber elasticity The adhesion of the body will not drop. For this reason, corrosion resistance can be improved and durability can be improved, maintaining a buffer effect. Further, it is possible to save the trouble of applying a rust prevention treatment to the exposed link or the like not covered with the rubber elastic body after the rubber elastic body is coated.

  In particular, according to the sixth and seventh inventions, since it becomes obvious at a glance whether or not the portion covered with the rubber elastic body has been plastically deformed, the inspection work of the falling bridge prevention member after a large earthquake can be performed more easily and in a short time. Can be done. For this reason, the maintenance cost can be reduced.

It is a perspective view which shows the case where the fallen bridge prevention member which concerns on 1st Embodiment of this invention is connected between the bridge abutment B made from concrete, and the bridge girder H which consists of H steel, and is shown in a circle. It is an enlarged view of the fallen bridge prevention part which concerns on embodiment. It is a top view which shows a fallen bridge prevention member same as the above. It is a perspective view which shows the weak point part of the fall bridge prevention member same as the above. It is a perspective view which shows only the weak point part chain of the weak point part same as the above. It is a horizontal sectional view of a fallen bridge prevention member same as the above. It is a perspective view which shows the weak point part of the fallen bridge prevention member which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the weak point part of the falling bridge prevention member which concerns on 3rd Embodiment of this invention. It is a horizontal sectional view which shows the conventional fallen bridge prevention member.

  Hereinafter, a fallen bridge prevention member according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
First, a fallen bridge preventing member according to the first embodiment of the present invention will be described with reference to FIGS. The falling bridge prevention member 1 according to the first embodiment of the present invention is a state in which a bridge lower structure such as an abutment or a bridge pier and a bridge upper structure such as a bridge girder are slackened as shown in FIG. And has a function of preventing the bridge upper structure from falling from the bridge lower structure.

  FIG. 1 illustrates a case where a reinforced concrete abutment B and a bridge girder H made of H steel are connected. Note that the illustrated embodiment illustrates a case where only one falling bridge prevention member 1 is installed, but it is needless to say that a plurality may be provided according to the scale of the bridge.

  As shown in FIGS. 1, 2, and the like, the falling bridge preventing member 1 according to the present embodiment is a member having a chain as a base material, which is a connecting material according to the present invention in which a plurality of links are connected to each other. And the general part 3 other than that. The weak point portion 2 is lower in strength than the general portion 3 with respect to the impact load during an earthquake. Further, the phrase “low strength against impact load” includes not only simply low tensile strength but also includes cases where the toughness is low and brittle fracture is easily caused by impact load.

<Weak point>
As shown in FIGS. 2 to 5, the weak point portion 2 includes a weak point portion chain 4 in which a plurality of links are connected to each other, and a rubber cover 5 that covers a part of the weak point portion chain 4. Yes.

(Weak point chain)
As shown in FIG. 4 and the like, the weak point chain 4 is a link connection body in which a plurality of links 41 to 45 processed into an ellipse shape from a bar are connected so that the axes of the links are orthogonal to each other. . As shown in FIG. 5, the weak point chain 4 is covered with a rubber elastic body and solidified in a state where all four connecting portions of the plurality of links 41 to 45 have gaps D of a predetermined interval. Yes. In addition, the illustrated gap D is an interval corresponding to one diameter of the links 41 to 45 in the present embodiment.

  In this embodiment, the links 41 to 45 are formed by connecting and processing an ellipse from a 19 mm diameter round bar manufactured by quenching and tempering heat treatment in chrome molybdenum steel (SCM420H). Yes. Of course, it goes without saying that the type and wire diameter of the steel material may be appropriately selected.

  In addition, although the weak point part chain 4 of the falling bridge prevention member 1 which concerns on this embodiment is comprised by the five links 41-45, you may be comprised by more links than this. Moreover, in the fallen bridge prevention member 1 which concerns on this embodiment, as shown in FIG. 2, the shackle 6 is attached to the links 41 and 45 of both ends, and length adjustment is possible. Of course, it is obvious that the shackle 6 functions as a falling bridge prevention member even without it.

(Rubber sheath)
As shown in FIG. 3 and the like, the rubber cover 5 is a member formed from a rubber elastic body into a columnar shape having a diameter of about 100 to 300 mm, and a part of the links 41 and 45 at both ends of the weak point chain 4 is exposed. In this state, the remaining links 42, 43 and 44 are completely covered. Since the rubber elastic body constituting the rubber covering 5 according to the present embodiment has a large resistance and repulsion, hard rubber obtained by mixing and vulcanizing natural rubber and synthetic rubber is employed. The rubber elastic body constituting the rubber cover 5 is preferably a hard rubber excellent in weather resistance and ultraviolet resistance, but any rubber elastic body having a buffering action against an impact load may be used. As long as there is a buffering action, the rubber covering 5 may be composed of another elastic body such as an elastic-plastic body or a viscoelastic body.

  Here, the rubber elastic body has a rubber elasticity that the Young's modulus at room temperature is about 1 to 10 MPa and that it expands greatly without breaking with a small stress, and that it returns almost instantaneously when the external force is removed. Pointing to the object shown. Hard rubber refers to rubber elastic bodies that have a hardness of 70 ° or more according to JISK6253 durometer hardness test (type A) by adding a large amount of sulfur to raw rubber such as chloroprene rubber and nitrile rubber. Yes.

  In addition, the rubber covering 5 covers the weak point chain 4 in a state where the gaps D are opened at four connecting portions of the five links 41 to 45.

  Of course, the shape of the rubber covering 5 is not limited to a columnar shape, but may be an outer shape as long as a part of the weak chain 4 is covered and solidified at a predetermined interval, such as a prismatic shape or a cross-shaped cross section. The shape such as is not particularly limited.

<General part>
As shown in FIGS. 1 and 2, the general portion 3 includes a general portion chain 7 including a link having a diameter slightly larger than the links 41 to 45 of the weak point chain 4 described above. The link 70 constituting the general chain 7 is processed and connected into an oval shape from a round bar having a diameter of 22 mm manufactured by quenching and tempering heat treatment in chrome molybdenum steel (SCM420H) in the same manner as the links 41 to 45. What has been adopted is adopted.

  Therefore, the general part chain 7 is subjected to the same heat treatment from the same material as the weak part chain 4 and has a larger link diameter than the weak part chain 4. For this reason, the general part chain 7 is stronger than the weak point part chain 4 with respect to an impact load during an earthquake.

<Conventional falling bridge prevention member>
Next, for comparison, a conventional falling bridge prevention member will be briefly described with reference to FIG. As shown in FIG. 8, the conventional falling bridge prevention member 10 (see also Patent Document 1) includes five of the seven links 11 to 17 of the chain R1 by a cylindrical rubber covering R2 made of a rubber elastic body. The links 12 to 16 are completely covered, and part of the links 11 and 17 at both ends are covered. In addition, since the part ahead of the shackle 6 is equivalent to the above-mentioned general part chain 7, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  It is considered that the impact absorbing effect of the fallen bridge prevention member is largely due to the buffering action of the rubber elastic body that has entered the gap of the link connecting portion. This has been confirmed by a buffer function confirmation experiment and a repeated loading performance test. The falling bridge prevention member 1 according to the first embodiment shows a buffer function and repeated loading performance equal to or higher than those of the conventional falling bridge prevention member 10. Yes.

  Further, in the conventional fallen bridge prevention member 10, after the chain R1 is covered with the rubber covering R2 made of a rubber elastic body, the exposed portion is subjected to rust prevention treatment by rust prevention coating or the like. This is because the links 11 to 17 of the chain R1 are tempered and tempered in chromium molybdenum steel (SCM420H) to strengthen the strength and toughness. This is because the material is rapidly cooled, and the strengthened strength and toughness are restored to the original values.

  For this reason, in the conventional fallen bridge prevention member 10, the part covered with the rubber elastic body was not subjected to the plating treatment in consideration of adhesion to the rubber elastic body. On the other hand, the hot dip galvanization etc. were given to the part ahead of the shackle 6 which is not coat | covered with a rubber elastic body. However, as described above, there is a concern about strength reduction when plating is performed after the heat treatment. Therefore, in the conventional falling bridge prevention member 10, the wire diameter of the link of the chain has been raised by one rank just in case.

<The effect of the fallen bridge prevention member which concerns on 1st Embodiment>
On the other hand, in the falling bridge prevention member 1 according to the first embodiment, both the weak point chain 4 and the general part chain 7 are subjected to plating treatment such as hot dip galvanization. Thereafter, the weak point chain 4 covered with the rubber elastic body is shot blasted and then covered with the rubber covering body 5 made of the rubber elastic body to be solidified. Since the shot blasting is performed in this way, the falling bridge prevention member 1 is inferior to the case where the adhesion force to the weak point chain 4 of the rubber covering 5 is not plated as compared with the falling bridge prevention member 10 and the shock absorbing buffer. The effect is also high. In addition, after coating with the rubber elastic body, it is possible to save the trouble of applying the rust prevention treatment to the exposed portion of the weak point chain 4.

  In addition, although hot dip galvanization was illustrated and demonstrated as a rust prevention process, the rust prevention process is not restricted to hot dip galvanization, For example, you may be other rust prevention processes, such as electroplating, electroless plating, and vapor deposition. In short, any treatment that can prevent rusting over a desired period of time may be used. The shot blasting is also a rough surface treatment in which the surface becomes rough, and is not particularly limited to shot blasting as long as it is a treatment that improves the adhesion to the rubber elastic body.

  Further, as described above, in the falling bridge prevention member 1 according to the first embodiment, the weak point chain 4 and the general part chain 7 are in the same condition until the shot blasting, so the weak point chain 4 is the general part. The strength is lower than the chain 7 with respect to the impact load during an earthquake. For this reason, when a large impact load is applied to the falling bridge prevention member 1, the portion that is broken becomes the weak point chain 4. For this reason, it is possible to determine whether or not the fallen bridge prevention member 1 should be replaced only by visually inspecting the rubber covering 5 of the fallen bridge prevention member 1 after a major earthquake, and the inspection after the earthquake can be easily performed in a short time. Yes. Moreover, only the weak point part 2 between the shackle 6 and the shackle 6 should be replaced | exchanged, the replacement cost of the falling bridge prevention member 1 can be reduced, and a life cycle cost can be reduced.

  In addition, although the weak point part 2 of the fallen bridge prevention member 1 which concerns on this embodiment was set so that tensile strength might become low by making the wire diameter of the link of a chain smaller than the general part 3, the weak point part chain 4 of steel materials The material itself may have a low tensile strength. Further, it is possible to make brittle fracture with respect to an impact load during an earthquake by lowering the toughness of the general part 3 by heat treatment such as heating and quenching only the weak point part 2. In short, it is only necessary that the weak part 2 is lower in strength against the impact load at the time of earthquake than the other parts.

  In addition, according to the falling bridge prevention member 1 according to the first embodiment, a portion that has been conventionally treated by rust prevention coating can be subjected to rust prevention treatment by plating treatment at a time. For this reason, the time required for the anticorrosion coating can be reduced, and the manufacturing cost of the falling bridge prevention member 1 can also be reduced.

  In addition, according to the fallen bridge prevention member 1 according to the first embodiment, since the periphery of the weak point chain 4 is solidified by a rubber elastic body, there is no possibility that a broken metal piece or the like is scattered around and the broken metal The risk of falling accidents where pieces fall can be eliminated. In addition, the shock load can be obtained by absorbing the impact load with the rubber elastic body.

[Second Embodiment]
Next, a fallen bridge preventing member according to a second embodiment of the present invention will be described with reference to FIG. The point of difference between the fallen bridge preventing member 1 ′ according to the second embodiment and the fallen bridge preventing member 1 according to the first embodiment described above is that the rubber covered body 5 ' Since only the mark M1 that can confirm that 'is plastically deformed is attached, this point will be described in detail, and the other description will be omitted.

  The mark M1 is a straight line made of a weather-resistant paint or the like along the length direction of the cylindrical outer peripheral surface of the rubber covering 5 '. When a large impact load is applied to the falling bridge prevention member 1 ′ due to a large earthquake, the above-described weak point chain 4 is broken. When the weak spot portion chain 4 is broken, the rubber elastic body of the rubber covering 5 'is plastically deformed, and the mark M1 is not straight. For this reason, it is possible to easily confirm whether or not the fallen bridge prevention member 1 ′ needs to be replaced visually.

  Therefore, according to the falling bridge prevention member 1 ′ according to the second embodiment, it is obvious whether the weak chain 4 is broken and the rubber elastic body portion is plastically deformed. Inspection work can be performed more easily and in a short time, and maintenance costs can be reduced.

[Third Embodiment]
Next, with reference to FIG. 7, a description will be given of the mark M2 of the falling bridge prevention member 1 ″ according to the third embodiment, which is a modification of the mark M1 of the weak point portion 2 ′ of the falling bridge prevention member 1 ′ according to the second embodiment. As shown in Fig. 7, the weak point 2 "of the fallen bridge prevention member 1", which is a modified example of the weak point 2 ', has a dot-like line (dot line) in which the mark M1 that is a straight line is formed. Mark M2.

  According to the dot line mark M2, it is possible not only to confirm whether or not the arrangement of dots is no longer linear, but it is possible to confirm the same as the above-described mark M1, and the weak chain 4 is broken and the rubber covering is broken. Even when 5 ″ partially extends in the axial direction and undergoes plastic deformation, it can be visually confirmed due to the difference in dot spacing.

  As described above, the fallen bridge preventing member according to the embodiment of the present invention has been described in detail, but the above-described or illustrated embodiment is merely an embodiment that is embodied in carrying out the present invention, Therefore, the technical scope of the present invention should not be construed in a limited manner. In particular, as an example, a link processed from a round bar into an oval shape has been described. However, the link is not limited to an oval shape, and is particularly limited as long as it forms a chain such as a circle or a rhombus. is not. Moreover, it is applicable even if it is square steel and hexagonal steel.

1, 1 ', 1 ": Falling bridge prevention member 2, 2', 2": Weak part 3: General part 4: Weak part chain (connecting material)
41-45: Link 5, 5 ', 5 ": Rubber covering (rubber elastic body)
6: Shackle 7: General chain (connecting material)
70: Links M1, M2: Mark D: Gap B: Abutment (underbridge structure)
H: Bridge girder (bridge superstructure)
10: Conventional falling bridge prevention members 11-17: Conventional link R1: Conventional chain (connecting material)
R2: Conventional rubber covering

Claims (7)

A fall prevention member that connects a bridge upper structure such as a bridge girder and a bridge lower structure such as an abutment or a pier to prevent the bridge upper structure from falling.
It is provided with a connecting material such as a chain and a rope for connecting the bridge lower structure and the bridge upper structure, and a weak point portion having a lower strength against an impact load at the time of an earthquake than another part of the connecting material. A fallen bridge prevention member characterized in that is formed. The connecting material is a chain in which a plurality of links made of steel are connected, and the weak point portion has a smaller wire diameter than the other portions, a low tensile strength of the link material, or a heat treatment. The falling bridge prevention member according to claim 1, wherein the strength is lower than that of other portions with respect to an impact load during an earthquake. The falling bridge prevention member according to claim 2, wherein a plating layer such as hot dip galvanization is formed after heat treatment is applied to all or a part of the plurality of links of the connecting material. The fallen bridge prevention member according to any one of claims 1 to 3, wherein a periphery of the weak point portion is solidified with a rubber elastic body. The fallen bridge prevention member according to claim 4, wherein the weakened portion is solidified by the rubber elastic body after a rough surface treatment such as shot blasting is performed. The falling bridge prevention member according to claim 4 or 5, wherein a mark capable of confirming plastic deformation is attached to a surface of the solidified rubber elastic body. The fall mark prevention member according to claim 6, wherein the mark is a straight line or a straight dot.

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