JP6649807B2 - Falling bridge prevention member - Google Patents

Description

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

  In a general bridge, the bridge upper structure such as a bridge girder and the bridge lower structure such as an abutment and a pier are not rigidly joined, but they are joined by a roller bearing or a pin bearing via a bearing member. It has a structure that has been. 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 bridge prevention member such as a bridge prevention chain that prevents the bridge upper structure from falling off the bridge lower structure. Have been.

  Conventionally, as this type of bridge prevention member, a buffer chain in which links are connected to each other 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 links 6 are embedded in the elastic body 7 in a state where the links 6 are fitted to each other with a gap so that each of the links 6 does not contact each other, and the entire links 6 are linearly aligned. The gap is also filled with the elastic body 7 so that one end of the buffer member 5 formed in a substantially rod shape 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 drop prevention structure fixed to the vicinity of the end of the pier 1 or the adjacent girder 2A by the member 8 is disclosed (Claim 1 of the patent document 1 and paragraphs [0017] to [1] of the specification. 0022], see FIGS. 1 and 2 of the drawings).

  However, in the girder drop prevention structure described in Patent Literature 1, although the elastic body 7 such as rubber has a buffering effect, the elastic body 7 is overwhelmingly lower in strength than the link 6, so that it is made of a rubber material. There was almost no difference in strength between the coated part and the non-coated part. Therefore, in the event of a large-scale earthquake, it was unknown which part of the plurality of links 6 would break. For this reason, if there is a large-scale earthquake, it is difficult to check whether all parts of the girder fall prevention structure are damaged or not. There was a problem. In addition, in the case of breakage, there is a possibility that the bridge may be broken by means other than the cushioning member 5, and there is also a problem that a broken metal piece may fall on a lower bridge in a bridge or the like that crosses three-dimensionally. .

  Further, Patent Literature 2 discloses a connecting member 11 having both ends connected to an abutment 1 and a bridge girder 2 and having an elastic portion 11 which can partially expand and contract, and a metal member in a state where the elastic portion 11a is shortened. A buffer mechanism housed in the sleeve 13 and having both ends fixed to the inner periphery of the metal sleeve 13. The metal sleeve 13 is formed with a number of slits 15 extending in the circumferential direction at intervals in the axial direction. The disclosed bridge drop prevention device is disclosed (see claim 1 of the patent document 2, paragraphs [0009] to [0013] of the specification, FIGS. 1 and 2 in the drawings).

  However, the bridge-fall prevention device described in Patent Literature 2 can absorb a part of the impact energy by plastically deforming the slit 15 of the metal sleeve 13 or the like, but which part of the link chain 11 is broken. Could not be identified. For this reason, as with the girder drop prevention structure described in Patent Literature 1, it cannot solve the problem that it takes time and effort to perform an inspection after an earthquake and the problem that there is a danger of a fall accident. Was.

JP-A-9-242019 JP 2010-53618 A

  The present invention has been devised in view of the above-mentioned problems, and has as its object the purpose of performing inspection after an earthquake easily and in a short time, and also making it easy to identify and replace a damaged portion during an earthquake. It is an object of the present invention to provide a stable bridge prevention member.

A bridge fall prevention member according to a first invention is a bridge fall prevention member for connecting 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. A connecting member such as a chain or a rope for connecting the lower structure and the bridge upper structure is provided, and a weak point portion having a lower strength against an impact load during an earthquake than another portion is formed in a part of the connecting material. The weak point portion is solidified by a rubber elastic body .

  In the bridge prevention member according to the second invention, in the first invention, the connecting member is a chain in which a plurality of links made of steel are connected, and the weak point portion has a wire diameter smaller than that of another portion. The tensile strength of the material of the link is low, or the strength of the link is lower than that of other parts due to an impact load during an earthquake due to heat treatment.

  The bridge fall prevention member according to a third invention is the second invention, wherein the heat treatment is applied to all or a part of the plurality of links of the connecting member, and then a plating layer such as hot-dip galvanizing is formed. Features.

A bridge-fall preventing member according to a fourth invention is the invention according to any one of the first to third inventions , wherein the weak point portion is solidified by the rubber elastic body after a rough surface treatment such as shot blasting is performed. It is characterized by being.

A bridge-fall preventing member according to a fifth aspect of the present invention is the device according to any one of the first to fourth aspects, wherein a mark is formed on a surface of the solidified rubber elastic body so that it can be confirmed that the rubber elastic body has been plastically deformed. It is characterized by.

Girder preventing member according to a sixth invention is the fifth invention, the mark is characterized by a straight line of a line or linear dot.

According to the first invention to the sixth invention, since the weak point portion having a low strength with respect to the impact load at the time of the earthquake is formed, the portion that is destroyed when a large impact load acts on the fall prevention member is the weak point portion. Becomes Therefore, if the weak point portion of the bridge prevention member is inspected only after the large earthquake, it can be determined whether or not the bridge prevention member should be replaced, and the inspection after the earthquake can be easily performed in a short time. In addition, only the weak part needs to be replaced, so that the replacement cost of the bridge prevention member can be reduced and the life cycle cost can be reduced.
Further, according to the first to sixth inventions, since the periphery of the weak point is solidified by the rubber elastic body, there is no possibility that the broken link or the like scatters around, and a fall accident in which the broken metal piece falls. Danger can be eliminated. In addition, the shock load can be absorbed by the rubber elastic body to provide a buffering effect.

  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 have been improved by the heat treatment are reduced. For this reason, according to the third aspect of the present invention, a part that has been separately treated by rust-preventive coating instead of the conventional plating treatment can be subjected to rust-preventive treatment by plating at one time. For this reason, the time required for the rust-proof coating can be reduced, and the manufacturing cost of the bridge prevention member can be reduced.

In particular, according to the fourth aspect, the weak point 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 bridge prevention member is improved, but also the rubber elasticity is improved. The adhesion of the body does not fall. For this reason, corrosion resistance can be improved while maintaining the buffer effect, and durability can be improved. Further, it is possible to save the trouble of performing a rust-proof treatment after covering the exposed portion of the link or the like which is not covered with the rubber elastic body with the rubber elastic body.

In particular, according to the fifth and sixth aspects of the present invention, it becomes clear at a glance whether or not the portion covered with the rubber elastic body has been plastically deformed. Can be done with For this reason, maintenance costs can be reduced.

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

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

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

  FIG. 1 illustrates a case in which an abutment B made of reinforced concrete and a bridge girder H made of H steel are connected. In addition, although the illustration shows the example in which the bridge prevention member 1 is installed at only one place, it is needless to say that a plurality of bridge prevention members 1 may be provided according to the scale of the bridge.

  As shown in FIGS. 1 and 2, etc., the falling bridge prevention member 1 according to the present embodiment is a member having a base as a chain, which is a connecting material according to the present invention in which a plurality of links are connected to each other, and has a weak point 2 And a general part 3 other than the above. The weak point portion 2 has a lower strength against an impact load during an earthquake than the general portion 3. In addition, the term “low in strength against an impact load” includes not only the case where the tensile strength is simply low, but also the case where the toughness is low and the brittle fracture easily occurs in response to the impact load.

<Weak points>
As shown in FIGS. 2 to 5, the weak part 2 includes a weak part chain 4 in which a plurality of links are connected to each other, a rubber covering body 5 that covers a part of the weak part chain 4, and the like. I have.

(Weak chain)
As shown in FIG. 4 and the like, the weak part chain 4 is a link connecting body in which a plurality of links 41 to 45 formed into an oval shape from a bar are connected such that the axes of the links are orthogonal to each other. . As shown in FIG. 5, the weak part chain 4 is solidified by being covered with a rubber elastic body with all four connecting portions of a plurality of links 41 to 45 having a predetermined gap D therebetween. I have. In the present embodiment, the illustrated gap D is an interval equivalent to one diameter of the links 41 to 45.

  In the present embodiment, the links 41 to 45 are formed by processing and linking a round bar having a diameter of 19 mm manufactured by quenching chrome molybdenum steel (SCM420H) and performing a heat treatment for tempering. I have. Of course, it goes without saying that the type and wire diameter of the steel material may be appropriately selected.

  In addition, the weak part chain 4 of the bridge prevention member 1 according to the present embodiment includes five links 41 to 45, but may include more links. In addition, in the fall prevention member 1 according to the present embodiment, as shown in FIG. 2, shackles 6 are attached to the links 41 and 45 at both ends so that the length can be adjusted. Of course, it is clear that the shackle 6 functions as a bridge prevention member even without the shackle.

(Rubber coating)
As shown in FIG. 3 and the like, the rubber covering 5 is a member formed from a rubber elastic body into a cylindrical 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 part chain 4 is exposed. In this state, the remaining links 42, 43 and 44 are completely covered. The rubber elastic body constituting the rubber coating 5 according to the present embodiment employs a hard rubber obtained by mixing natural rubber and synthetic rubber and vulcanizing the rubber elastic body since the rubber elastic body has high resistance and repulsion. The rubber elastic body constituting the rubber coating 5 is preferably a hard rubber having excellent weather resistance and ultraviolet resistance. However, any rubber elastic body having a buffering action against an impact load may be used. The rubber coating 5 may be made of another elastic body such as an elastoplastic body or a viscoelastic body as long as it has a buffering action on the elastic member.

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

  In addition, the rubber covering body 5 covers the weak part chain 4 in a state where a gap D is left between the four connecting portions of the five links 41 to 45.

  Needless to say, the shape of the rubber coating 5 is not limited to a columnar shape, but may be a prismatic shape, a cross-sectional shape, or the like, as long as a part of the weak part chain 4 is covered and solidified at a predetermined interval. Is not particularly limited.

<General part>
As shown in FIGS. 1 and 2, the general portion 3 includes a general portion chain 7 and the like having a diameter slightly larger than the links 41 to 45 of the weak portion chain 4. Similarly to the links 41 to 45, the link 70 constituting the general part chain 7 is formed by quenching chrome molybdenum steel (SCM420H) and performing a heat treatment of tempering to form and connect a round bar having a diameter of 22 mm into an oval shape. What has been 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 wire diameter than the weak part chain 4. Therefore, the strength of the general part chain 7 is higher than that of the weak part part chain 4 against an impact load during an earthquake.

<Conventional bridge prevention members>
Next, a conventional bridge prevention member will be briefly described with reference to FIG. 8 for comparison. As shown in FIG. 8, the conventional bridge-fall preventing member 10 (see also Patent Document 1) has five cylindrical links R <b> 2 made of a rubber elastic body, among five links 11 to 17 of a chain R <b> 1. Are completely covered, and some of the links 11, 17 at both ends are covered. Note that the parts after the shackle 6 are the same as those of the above-described general part chain 7, and thus the same reference numerals are given and the description is omitted.

  It is considered that the shock absorbing effect of the falling bridge prevention member largely contributes to the buffering action of the rubber elastic body that has entered the gap between the link connecting portions. This has been confirmed by a buffer function confirmation experiment and a test of repeated loading performance, and the bridge prevention member 1 according to the first embodiment shows a buffer function and repeated loading performance equal to or higher than that of the conventional bridge prevention member 10. I have.

  Further, in the conventional bridge drop 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 quenched into chromium molybdenum steel (SCM420H) and subjected to a heat treatment of tempering to strengthen the strength and toughness. This is because quenching occurs and the strengthened strength and toughness return to the original level and decrease.

  For this reason, in the conventional bridge-fall preventing member 10, the portion covered with the rubber elastic body is not plated in consideration of the adhesion to the rubber elastic body. On the other hand, the portion ahead of the shackle 6 not covered with the rubber elastic body was subjected to hot-dip galvanizing or the like. However, as described above, if the plating is performed after the heat treatment, the strength may be reduced. Therefore, in the conventional bridge-fall preventing member 10, the wire diameter of the link of the chain is raised by one rank just in case.

<Operation and effect of bridge prevention member according to first embodiment>
On the other hand, in the fall prevention member 1 according to the first embodiment, both the weak part chain 4 and the general part chain 7 are subjected to a plating process such as hot-dip galvanizing. Thereafter, the weak 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 and solidified. Since the shot blasting is performed in this manner, the bridge-preventing member 1 has the same adhesive strength as that of the bridge-preventing member 10 with respect to the weak portion chain 4 of the rubber coating 5 as compared with the case where the plating is not plated, and has a shock absorbing buffer. The effect is also high. In addition, after covering with the rubber elastic body, it is possible to save the trouble of performing the rust prevention treatment on the exposed portion of the weak part chain 4.

  The rust-prevention treatment has been described by exemplifying hot-dip galvanization. However, the rust-prevention treatment is not limited to hot-dip galvanization, and other rust-prevention treatments such as electroplating, electroless plating, and vapor deposition may be used. In short, any process that can prevent rusting for a desired period or more may be used. Further, shot blasting is also a roughening treatment so that the surface becomes rough, and is not particularly limited to shot blasting as long as it is a treatment that improves the adhesive force with the rubber elastic body.

  Further, as described above, in the bridge prevention member 1 according to the first embodiment, the weak part chain 4 and the general part chain 7 have the same conditions until before shot blasting. The chain 7 is lower in strength against an impact load during an earthquake than the chain 7. For this reason, when a large impact load is applied to the falling bridge prevention member 1, the portion to be broken is the weak part chain 4. For this reason, if the rubber covering 5 of the bridge prevention member 1 is visually inspected after a large earthquake, it can be determined whether or not the bridge prevention member 1 should be replaced, and the inspection after the earthquake can be easily and quickly performed. I can do it. Further, only the weak portion 2 between the shackle 6 and the shackle 6 needs to be replaced, so that the replacement cost of the bridge prevention member 1 can be reduced, and the life cycle cost can be reduced.

  The weak point portion 2 of the bridge prevention member 1 according to the present embodiment is set so that the tensile strength becomes lower by making the wire diameter of the link of the chain smaller than that of the general portion 3. The material itself may have a low tensile strength. Further, the toughness may be made lower than that of the general part 3 by heat treatment such as heating and quenching only the weak point part 2 so that the brittle fracture is easily caused by the impact load at the time of the earthquake. In short, it is only necessary that the weak point portion 2 has a lower strength against an impact load during an earthquake than other portions.

  In addition, according to the bridge prevention member 1 according to the first embodiment, the rust-preventive treatment can be performed at once by plating even the part that has been conventionally treated by the rust-preventive coating. For this reason, the time required for the rust prevention coating can be reduced, and the manufacturing cost of the bridge prevention member 1 can be reduced.

  In addition, according to the bridge prevention member 1 according to the first embodiment, since the periphery of the weakened part chain 4 is solidified by the rubber elastic body, there is no possibility that broken metal pieces and the like are scattered around. The danger of a falling accident in which a piece falls can be eliminated. In addition, the impact load can be absorbed by the rubber elastic body to provide a buffering effect.

[Second embodiment]
Next, a bridge prevention member according to a second embodiment of the present invention will be described with reference to FIG. The bridge prevention member 1 'according to the second embodiment is different from the bridge prevention member 1 according to the above-described first embodiment in that the outer peripheral surface of the rubber covering 5' of the weak point portion 2 'has a rubber covering 5'. 'Is only the point where the mark M1 that can be confirmed to have been plastically deformed is attached, so that point will be described in detail, and other description will be omitted.

  The mark M1 is a linear line made of weather-resistant paint or the like along the length direction of the cylindrical outer peripheral surface of the rubber coating 5 '. When a large impact load is applied to the bridge prevention member 1 'due to a large earthquake, the above-mentioned weak portion chain 4 is broken. When the weak part chain 4 is broken, the rubber elastic body of the rubber coating 5 'is plastically deformed, and the mark M1 is not linear. Therefore, it is possible to easily visually check whether or not the replacement of the bridge prevention member 1 'is necessary.

  Therefore, according to the bridge prevention member 1 'according to the second embodiment, it is clear at a glance whether or not the weak part chain 4 is broken and the rubber elastic portion is plastically deformed. Inspection work can be performed more easily in a short time, and maintenance costs can be reduced.

[Third embodiment]
Next, a mark M2 of a bridge prevention member 1 ″ according to the third embodiment, which is a modification of the mark M1 of the weak portion 2 ′ of the bridge prevention member 1 ′ according to the second embodiment, will be described with reference to FIG. As shown in Fig. 7, in the weak point portion 2 "of the bridge-fall preventing member 1" which is a modified example of the weak point portion 2 ', the mark M1 which was a straight line has become a dot line (dot line). The mark is M2.

  According to the mark M2 of the dot line, it is not only possible to confirm whether or not the arrangement of the dots is not linear but to confirm the same as the mark M1 described above. Even when 5 "partially extends in the axial direction and is plastically deformed, it can be visually confirmed by the difference in dot spacing.

  As described above, the bridge prevention member according to the embodiment of the present invention has been described in detail. However, the above-described or illustrated embodiments are merely ones embodied in practicing the present invention, These should not be construed as limiting the technical scope of the present invention. In particular, as an example, the link has been described as being formed from a round bar into an elliptical shape, but the link is not limited to the elliptical shape, but is particularly limited as long as the link forms a chain such as a circular shape or a diamond shape. is not. Further, the present invention can be applied to square steel and hexagonal steel.

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

Claims (6)

A bridge prevention member for connecting 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,
A connecting member such as a chain or a rope for connecting the bridge lower structure and the bridge upper structure, and a part of the connecting material, which is a weak point portion having a lower strength against an impact load during an earthquake than other portions; Is formed ,
A fall prevention member, wherein the periphery of the weak point is solidified by a rubber elastic body. The connecting material is a chain in which a plurality of links made of steel are connected, and the weak point is that the wire diameter of the link is smaller than other parts, the tensile strength of the material of the link is low, or by heat treatment. The fall prevention member according to claim 1, wherein the strength against the impact load at the time of the earthquake is lower than other portions. The bridge prevention member according to claim 2, wherein a plating layer such as hot-dip galvanizing is formed after heat treatment is performed on all or a part of the plurality of links of the connecting member. The fall prevention member according to any one of claims 1 to 3, wherein the weak point portion is solidified by the rubber elastic body after a rough surface treatment such as shot blasting is performed. The bridge prevention member according to any one of claims 1 to 4, wherein a mark is formed on a surface of the solidified rubber elastic body so as to confirm that the rubber elastic body has been plastically deformed. The bridge prevention member according to claim 5 , wherein the mark is a straight line or a linear dot.

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