Box girder rust-preventive member and box girder rust-preventive structure

Abstract

To provide a rust-preventive member for a box girder capable of suppressing the immersion of water into the inside while maintaining the strength of the box girder, and to provide a rust-preventive structure for the box girder using the same.SOLUTION: A vent hole 9 is formed in a side surface of a box girder 3. The internal space of the box girder 3 and the outside communicate with each other through the vent hole 9. A box girder rust-preventive member 11 is fixed to the vent hole 9. A main body 19 of the box girder rust-preventive member 11 is joined to the surface of the box girder 3 by welding. A water-shielding member 13 is disposed so as to cover an opening part of the main body 19, and the water-shielding member 13 is fixed to the main body 19 by a fixing member 21.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a box girder rust prevention member that is fixed to a steel box girder of a bridge or the like and used to prevent rust inside the box girder, and to a box girder rust prevention structure using the same. [Background technology]

[0002] Temperature changes can cause condensation inside box girders, which can lead to corrosion. For this reason, rust prevention is necessary for the inside of the box girders. Painting is generally used to prevent rust on the inside of steel box girders. However, this is problematic due to concerns about the effects of volatile organic compounds on the human body and the environment.

[0003] Another solution to this problem is to install a desiccant in the internal space of the box girder to control humidity, but this requires sealing the joints that make up the box girder to ensure airtightness. Silica gel, a desiccant used to prevent rust on the inside of the box girder, is said to keep the humidity constant by repeatedly absorbing and releasing moisture almost indefinitely, but this is a chemical process and its effectiveness decreases over time.

[0004] Furthermore, since 6 to 7 kg of desiccant is usually placed between each diaphragm, a total of 120 kg is used for a bridge length of 50 m (materials from the 63rd Annual Academic Conference of the Japan Society of Civil Engineers (September 2008)). However, the space inside the box girder is narrow, and the installation and removal (replacement) of large amounts of desiccant must be done manually, making work difficult.

[0005] In response to this, a method has been proposed in which air vents are provided in box girders at positions that will not cause structural or mechanical defects (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2002-161513 A Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, the ventilation holes are provided in a location where the strength reduction caused by the provision of the ventilation holes is unlikely to occur, so the degree of freedom in the location is low. Also, wire mesh can be placed to prevent birds and the like from entering through the ventilation holes, but there is a risk of water entering through the ventilation holes in the event of rain accompanied by strong winds such as a typhoon. Patent Document 1 also proposes a structure in which a hood is provided and the lid is closed by a sensor and a motor, but the structure is complex and further maintenance is required to keep it working.

[0008] The present invention has been made in consideration of such problems, and aims to provide a box girder rust prevention component that can prevent water from entering the interior while maintaining the strength of the box girder, and a box girder rust prevention structure using the same. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the first invention is a box girder rust prevention component that is fixed to a box girder, comprising a substantially ring-shaped main body portion with an opening in the center, a water-proofing member arranged to cover the opening of the main body portion, and a fixing structure for fixing the water-proofing member to the main body portion, wherein the water-proofing member is breathable and capable of suppressing the intrusion of water.

[0010] The water-blocking member may be subjected to a water-repellent treatment.

[0011] The water impermeable member is preferably a nonwoven fabric.

[0012] The fixing structure may be a fixing member constituted by a magnet, and the water-blocking member may be sandwiched and fixed between the fixing member and the main body.

[0013] The fixing structure may be a fixing member made of a plate-like material having a hole, and the water-blocking member may be sandwiched between the fixing member and the main body and fixed with a bolt.

[0014] The fixing structure may be a fixing member of a plate-shaped member having a plurality of holes, the holes consisting of a large diameter portion and a narrow portion narrower than the large diameter portion, the main body portion having a bolt-shaped protrusion at a position corresponding to the hole, the diameter of the large diameter portion being larger than the diameter of the head of the bolt-shaped protrusion, the width of the narrow portion being narrower than the diameter of the head of the bolt-shaped protrusion and wider than the diameter of the shaft of the bolt-shaped protrusion, and the head of the bolt-shaped protrusion may be inserted into the large diameter portion and then the fixing member may be moved to move the head of the bolt-shaped protrusion relative to the narrow portion, thereby sandwiching and fixing the water-proof member between the fixing member and the main body portion.

[0015] The fixing structure may be a fixing member and a plurality of mounting portions for attaching the fixing member to the main body portion, the mounting portions protruding from one end side of the main body portion with the tip side bent toward the center of the main body portion, and the fixing member and the water-proof member may be sandwiched and fixed between the fixing member and the main body portion by inserting the fixing member and the water-proof member between the plurality of mounting portions and the main body portion.

[0016] The main body may have a flange portion having a relatively large diameter, and a protrusion having a relatively small diameter protruding from one side of the flange portion.

[0017] According to the first invention, when an air vent is provided in the box girder, a ring-shaped box girder rust prevention member is fixed to the air vent and functions as a reinforcing member, thereby suppressing a decrease in the strength of the box girder due to the formation of the air vent. In addition, the water-blocking member can prevent water from entering the inside of the box girder. In this case, since the main body of the box girder rust prevention member also functions as an attachment part for the water-blocking member, there is no need to form a structure for directly fixing the water-blocking member to the box girder, and the attachment work is easy.

[0018] Furthermore, if the waterproof member is a nonwoven fabric, it is possible to efficiently prevent water from entering while ensuring breathability. Furthermore, if the waterproof member is subjected to a water-repellent treatment, it is possible to more reliably prevent water from soaking into the nonwoven fabric and entering the inside of the box girder.

[0019] Furthermore, if the fixing member for fixing the waterproof member is a magnet, the fixing and replacement work of the waterproof member is easy.

[0020] Furthermore, if the fixing member for fixing the waterproof member is a plate-like member having holes, the waterproof member can be fixed more reliably.

[0021] In addition, by providing a hole having a large diameter portion and a narrow portion in the fixing member, inserting the head of a bolt-shaped protrusion into the large diameter portion, and moving the fixing member so that the narrow portion is positioned at the head position, the water-proof member can be easily fixed without tightening the bolt.

[0022] In addition, by arranging an attachment part with a bent tip for attaching the fixing member to the main body part and inserting the fixing member and the water-proofing member between the bent parts of the multiple attachment parts and the main body part, the water-proofing member can be easily fixed without the need for bolt tightening.

[0023] In addition, if the main body portion has a flange portion with a relatively large diameter and a protrusion with a relatively small diameter protruding from one side of the flange portion, the protrusion makes it easy to adjust the axis of the air vent and the main body portion, and the flange portion makes it easy to position the insertion direction (axial direction) into the box girder.

[0024] The second invention is a box girder rust prevention structure using the box girder rust prevention member of the first invention, characterized in that an air hole is provided in at least a part of the box girder, the box girder rust prevention member is fixed to the outer periphery of the air hole, and the water-proof member suppresses the intrusion of water through the air hole.

[0025] The main body portion has a flange portion having a relatively large diameter and a protrusion having a relatively small diameter protruding from one side of the flange portion, and it is desirable that the flange portion has a diameter larger than the air vent and that the protrusion be inserted into the air vent from the inside of the box girder and fixed therein.

[0026] It is desirable that the tip of the protrusion protrudes a predetermined length from the outer surface of the box beam.

[0027] According to the second invention, it is possible to suppress a decrease in the strength of the box girder, ensure ventilation inside the box girder, and prevent water from entering from the outside. In this case, since the waterproofing member is fixed to the main body, the work can be carried out simply by attaching the main body to the box girder.

[0028] In addition, if the main body portion has a flange portion with a relatively large diameter and a protrusion with a relatively small diameter protruding from one side of the flange portion, the axis of the air vent and the main body portion can be easily adjusted by inserting the protrusion into the air vent, and the flange portion can be abutted against the inner surface of the box girder to easily position it in the insertion direction (axial direction) into the box girder.

[0029] In addition, by having the protrusion protrude from the outer surface of the box girder, water droplets flowing down the side of the box girder can be prevented from entering the air vent. Effect of the Invention

[0030] According to the present invention, it is possible to provide a box girder rust prevention member that can suppress the intrusion of water into the interior while maintaining the strength of the box girder, and a box girder rust prevention structure using the same. [Brief description of the drawings]

[0031] [Figure 1] A diagram showing a box girder 3 with a box girder rust prevention member 11 attached. [Diagram 2] Cross-sectional view taken along line AA in Figure 1. [Diagram 3] 13A is an enlarged view of part B, and FIG. 13B is a view showing another embodiment. [Figure 4] 6(a) and 6(b) are diagrams showing another embodiment of a method for fixing the water-blocking member 13. FIG. [Diagram 5] 6(a) to 6(c) are diagrams showing another embodiment of the method for fixing the water-blocking member 13. FIG. [Figure 6] 10A and 10B are diagrams showing another embodiment of a method for fixing the water-blocking member 13. [Figure 7]6(a) and 6(b) are diagrams showing another embodiment of a method for fixing the water-blocking member 13. FIG. [Figure 8] 6(a) and (b) are diagrams showing another embodiment of a method for fixing the main body portion 19. FIG.

[0032] Hereinafter, an embodiment of the present invention will be described. Fig. 1 is a diagram showing a box girder 3 to which a box girder anti-rust member 11 is attached, and Fig. 2 is a diagram showing a box girder anti-rust structure 10, which is a cross-sectional view taken along line AA in Fig. 1. In this embodiment, the box girder anti-rust member 11 is fixed to the box girder 3 in a bridge 1. The bridge 1 is configured such that a box girder 3 of a predetermined length is placed on piers 7 installed at predetermined intervals, and a main girder 5 is placed on the box girder 3. Note that the box girder 3 does not have to be placed in the illustrated configuration in the bridge 1.

[0033] The box girder 3 is, for example, a steel box girder, and steel is exposed at least in the internal space of the box girder 3. An air vent 9 is formed on the side of the box girder 3. The air vent 9 connects the internal space of the box girder 3 to the outside. The air vent 9 needs to be disposed at least in one place on the box girder 3, and may be disposed in a plurality of places as shown in the figure. Also, as shown in FIG. 2, the air vent 9 may be disposed at the same place on both opposing side surfaces of the box girder 3, and the arrangement of the air vents 9 formed on each side surface may be shifted in the longitudinal direction. The air vent 9 may also be formed on the bottom side of the box girder 3. That is, the air vent 9 needs to be provided in at least a part of the box girder 3.

[0034] A box girder anti-rust member 11 is fixed to each air vent 9 of the box girder 3. Fig. 3(a) is an enlarged view of part B in Fig. 2. The box girder anti-rust member 11 is composed of a main body 19, a waterproof member 13, a fixing member 21, etc. The main body 19 is made of steel and is a substantially ring-shaped member with an opening in the center. The main body 19 has a flange portion 17 with a relatively large diameter, and a protrusion 15 with a relatively small diameter that protrudes from one side of the flange portion 17.

[0035] The outer diameter of flange portion 17 is larger than the inner diameter of ventilation hole 9, and the outer diameter of protrusion 15 is slightly smaller than the inner diameter of ventilation hole 9. Therefore, when protrusion 15 is inserted into ventilation hole 9, the side surface of flange portion 17 abuts against the surface of box girder 3. In other words, protrusion 15 makes it possible to position the body portion 19 relative to box girder 3, and flange portion 17 makes it possible to determine the insertion length of body portion 19 into ventilation hole 9.

[0036] The main body 19 is joined by welding to the surface of the box girder 3. In the illustrated example, the outer peripheral surface of the flange portion 17 is welded to the box girder 3. That is, the main body 19 is fixed to the outer periphery of the air vent 9.

[0037] As shown in the figure, the protrusion 15 of the main body 19 is inserted into the vent hole 9 from the inside of the box girder 3 and fixed therein. In this way, installation work and the like can be performed from the inside of the box girder 3. If work can be performed from the outside of the box girder 3, the protrusion 15 of the main body 19 may be inserted into the vent hole 9 from the outside of the box girder 3 and fixed therein.

[0038] Here, when protrusion 15 is inserted from inside box girder 3, it is desirable that the tip of protrusion 15 protrudes a predetermined length from the outer surface of box girder 3. In other words, it is desirable that the length from flange portion 17 to the end of protrusion 15 is longer than the wall thickness of box girder 3. In this way, even if water droplets flow down the outer surface side of box girder 3, protrusion 15 can prevent the water droplets from flowing into vent hole 9.

[0039] The shape of main body 19 does not have to be circular, and can be any shape that matches the shape of ventilation hole 9.

[0040] A waterproof member 13 is disposed on the inner surface of the box girder 3 so as to cover the opening of the main body 19, and the waterproof member 13 is fixed to the main body 19 by a fixing member 21. The waterproof member 13 is a member capable of suppressing the intrusion of water. The waterproof member 13 is preferably a breathable member such as nonwoven fabric or silicone rubber. In particular, if the nonwoven fabric or the like is subjected to a water-repellent treatment, water droplets will not soak into the nonwoven fabric or the like, and the water can be repelled to prevent the inflow into the box girder 3. Even if the waterproof member 13 does not have breathability, if the waterproof member 13 can be easily attached and detached from the ventilation hole 9 under a predetermined condition such as a temperature change, the ventilation hole 9 can be opened, and condensation in the box girder can be suppressed. However, if the waterproof member 13 has breathability, such work is not necessary.

[0041] The fixing member 21 is a plate-like member having holes (holes corresponding to the openings of the main body portion 19). With the water-blocking member 13 sandwiched between the fixing member 21 and the main body portion 19, the water-blocking member 13 can be detachably fixed to the main body portion 19 by bolts 23. In this manner, the water-blocking member 13 can be positioned on the inside side of the box girder 3 rather than the outer surface of the box girder 3, thereby suppressing the effects of wind and the like outside the box girder 3.

[0042] As shown in FIG. 3(b), a fixing member 21a having many holes may be used instead of the ring-shaped fixing member 21. The fixing member 21a is, for example, a plate-like member having many small holes, such as punched metal, or a net. By using such a fixing member 21a, the water-blocking member 13 located at the opening of the main body 19 can be supported from the inner surface side. Also, a pair of fixing members 21a may be used to fix the water-blocking member 13 to the main body 19 in a state where it is sandwiched between the fixing members 21a. Also, the opening of the main body 19 itself may be formed with a plurality of holes.

[0043] 4(a), a fixing member 21b made of a magnet may be used. As described above, since the main body 19 is made of steel, the water-blocking member 13 can be sandwiched and fixed by the fixing member 21b. This makes it easier to attach and detach the water-blocking member 13 during installation, replacement, and other operations.

[0044] 4(b), a claw 25 may be used. In each of the above-described embodiments, a fixing member is used as the fixing structure for fixing the water-blocking member 13, but the water-blocking member 13 may be fixed by piercing the water-blocking member 13 into a claw 25 provided on the main body 19. If the tip of the claw 25 has a barb, the water-blocking member 13 is prevented from coming off the main body 19, and the fixing structure for the water-blocking member 13 can be easily formed.

[0045] 5(a), a fixing member 21c having holes 29 may be used. A plurality of holes 29 are formed near the periphery of a substantially ring-shaped (circular) fixing member. One end of the hole 29 is a large diameter portion 29a having a relatively large size, and the other end is a narrow width portion 29b having a relatively small width. In the fixing member 21c, the plurality of holes 29 are arranged at predetermined intervals such that the large diameter portion 29a side (narrow width portion 29b side) faces in the same circumferential direction.

[0046] 5(b), the bolts 23 are disposed in the main body 19 at positions corresponding to the holes 29 of the fixing member 21c. In this case, the diameter of the large diameter portion 29a of the hole 29 is larger than the diameter of the head of the bolt 23. The width of the narrow width portion 29b of the hole 29 is narrower than the diameter of the head of the bolt 23 and wider than the diameter of the shaft. Therefore, the bolts 23 can be inserted into the large diameter portions 29a of the respective holes 29.

[0047] 5(c), by rotating the fixing member 21c to the main body 19, the head of the bolt 23 moves relatively to the narrow portion 29b of the hole 29, and the fixing member 21c is fixed to the main body 19 by the head of the bolt 23. Note that a hole similar to the fixing member 21c may also be formed in the water-shielding member 13, or the water-shielding member 13 may be provided with only a circular hole through which the bolt 23 passes, and only the fixing member 21c may be rotated relatively to the water-shielding member 13 and the main body 19.

[0048] In this way, by hooking the heads of bolts 23 into holes 29, there is no need to tighten bolts 23 individually, and fixing members 21c and the like can be easily attached and detached. Note that what is fixed to main body 19 does not have to be a bolt, and any protrusion having a bolt-like shape will do. That is, it is sufficient that a bolt-like protrusion is provided in a portion of main body 19 corresponding to hole 29, and the diameter of large diameter portion 29a is larger than the diameter of the head of the bolt-like protrusion, and the width of narrow portion 29b is narrower than the diameter of the head of the bolt-like protrusion and wider than the diameter of the shaft of the bolt-like protrusion.

[0049] 6, fixing member 21d may be used in which holes 29 are aligned in one direction (up and down in the figure) instead of aligned in the circumferential direction. For example, by arranging large diameter portion 29a facing downward as shown in the figure, after bolt 23 of main body 19 is inserted into large diameter portion 29a, fixing member 21d shifts downward due to its own weight. At this time, the head of the bolt moves relatively to narrow width portion 29b of hole 29, and fixing member 21d can be easily fixed to main body 19.

[0050] In this way, as long as the head of the bolt-shaped projection can be inserted into the large diameter portion and then the fixing member can be moved relative to the main body portion 19 to move the head of the bolt-shaped projection to the narrow width portion 29b, the direction of movement is not particularly limited.

[0051] 7(a) and 7(b), mounting parts 31 for mounting a fixing member may be provided as a fixing structure for the water-blocking member 13. The mounting parts 31 are arranged at a predetermined interval in a plurality of locations so as to protrude (almost perpendicular to the end face) from one end side of the main body 19, for example, and each tip is bent toward the center of the main body 19 to have a substantially L-shaped configuration.

[0052] The fixing members 21e and the water-blocking members 13 are fixed to the main body 19 by overlapping and inserting the plate-like fixing members 21e and the water-blocking members 13, which do not have a structure such as a screw hole, between the multiple mounting portions 31 (their tip bent portions) and the main body 19. When the fixing members 21e and the water-blocking members 13 are inserted into the bent portions of the mounting portions 31, the water-blocking members 13 and the fixing members 21e can be deflected. Alternatively, the mounting portions 31 may be detachable from the main body 19, or movable in the circumferential direction.

[0053] As described above, the waterproof member 13 may be sandwiched between two fixing members 21e. In the present invention, even in such a case, the waterproof member 13 is sandwiched and fixed between one fixing member 21e and the main body 19 (via the other fixing member 21e).

[0054] In addition, in each of the above-described embodiments, an example has been described in which the main body portion 19 is fixed to the box girder 3 by welding, but as shown in Fig. 8(a), the main body portion 19 (flange portion 17) may be fixed to the box girder 3 by bolts 27. In this way, installation work can be performed even in places where welding is not possible.

[0055] 8(b), even when the main body 19 is fixed by welding, the protrusion 15 may be welded to the box girder 3 instead of the flange 17. In this case, the protrusion 15 may be tapered so that the outer diameter gradually decreases toward the tip, and welding may be performed between the inner surface of the vent hole 9 and the outer surface of the protrusion 15.

[0056] The box girder rust prevention structure 10 can be installed on the box girder 3 of an existing bridge or the like, and can also be applied to newly constructed box girders. When installing on an existing box girder 3, first, a vent hole is formed in a part of the existing box girder 3, and the main body 19 of the box girder rust prevention member 11 is fixed to the box girder 3. After that, the water-blocking members 13 are fixed to the respective main bodies 19.

[0057] On the other hand, when applying to a newly constructed box girder 3, ventilation holes 9 are formed in advance in some of the parts constituting the box girder 3, and the main body 19 is fixed to the ventilation holes 9. After that, the parts are transported to the site, and the box girder 3 is assembled and installed there, and finally, the waterproofing members 13 are attached to each of the main body parts 19. Note that the installation of the waterproofing members 13 may be performed before the assembly of the box girder.

[0058] As described above, according to this embodiment, by forming the ventilation holes 9 in the box girder 3, it is possible to suppress the occurrence of condensation inside the box girder and to suppress rusting due to condensation. In addition, since the main body 19 is fixed to the outer periphery of the ventilation holes 9, the ventilation holes 9 are reinforced and a decrease in strength due to the formation of the ventilation holes 9 can be suppressed. Therefore, there are few restrictions on the position where the ventilation holes 9 are formed, and any number of ventilation holes 9 can be formed at any position. Therefore, for example, it is possible to suppress an increase in carbon dioxide concentration due to long-term sealing, and it can also be used to provide light when working inside the box girder 3.

[0059] Furthermore, since the waterproofing member 13 can be fixed to the main body 19, it is possible to prevent water and small animals from entering the inside of the box girder 3 from the outside. In this case, since there is a fixing member (fixing structure) for fixing the waterproofing member 13 to the main body 19, the fixing work is easy and there is no need to form a structure for fixing the waterproofing member 13 on the box girder 3.

[0060] The waterproof member 13 may be any member that is breathable and prevents water from entering, and may be, for example, a louver-like member. Although the waterproof member 13 is fixed to the main body 19 inside the box girder 3, it may be installed in a double layer inside and outside the main body 19 (inside and outside the box girder 3). In this case, the inside and outside waterproof members 13 may be different.

[0061] Furthermore, by providing the flange portion 17 and the protrusion 15 on the main body portion 19, it is easy to position the main body portion 19 when fixing it. Furthermore, since the protrusion 15 protrudes outward from the box girder 3 and a canopy is formed on the outer periphery of the ventilation hole 9, it is possible to more reliably prevent water from entering the ventilation hole 9.

[0062] Although the embodiment of the present invention has been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the above-described embodiment. It is clear that a person skilled in the art can think of various modifications or alterations within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0063] For example, it goes without saying that the embodiments described in the respective drawings can be combined with each other. [Explanation of symbols]

[0064] 1. Bridge 3...Box girder 5……Main digit 7………Pier 9...Ventilation hole 10………Box girder rust-proof structure 11....Anti-corrosion components for box girders 13...Water-impermeable material 15………Protrusion 17...Flange section 19...Main body 21, 21a, 21b...Fixing members 23………Bolt 25...Claws 27………Bolts 29……hole 29a………Large diameter section 29b……Narrow part 31………Mounting part

Claims

1. A box girder rust prevention member fixed to a box girder, A substantially ring-shaped main body having an opening at the center; A waterproof member arranged to cover the opening of the main body; A fixing structure for fixing the waterproof member to the main body portion; Equipped with The water-proofing member is a box girder rust-preventive member characterized in that it has breathability and is capable of suppressing the infiltration of water.

2. 2. The rust-preventive member for box girder according to claim 1, wherein the water-proofing member is subjected to a water-repellent treatment.

3. 2. The rust-preventive member for a box girder according to claim 1, wherein the waterproofing member is a nonwoven fabric.

4. The box girder rust prevention member according to claim 1, characterized in that the fixing structure is a fixing member composed of a magnet, and the water-proofing member can be fixed by being sandwiched between the fixing member and the main body portion.

5. The box girder rust prevention member as described in claim 1, characterized in that the fixing structure is a fixing member made of a plate-shaped material having a hole, and the water-proofing member can be sandwiched between the fixing member and the main body and fixed with a bolt.

6. The fixing structure is a fixing member made of a plate-like member having a plurality of holes, the holes being composed of a large diameter portion and a narrow portion narrower than the large diameter portion, the main body being provided with a bolt-shaped protrusion at a position corresponding to the hole, the diameter of the large diameter portion being larger than the diameter of a head of the bolt-shaped protrusion, the width of the narrow portion being narrower than the diameter of the head of the bolt-shaped protrusion and wider than the diameter of a shaft of the bolt-shaped protrusion, The box girder rust prevention member described in claim 1, characterized in that the head of the bolt-shaped projection is inserted into the large diameter portion and then the fixing member is moved to move the head of the bolt-shaped projection relative to the narrow width portion, thereby sandwiching and fixing the water-proof member between the fixing member and the main body portion.

7. The box girder rust prevention member described in claim 1, characterized in that the fixing structure is a fixing member and a plurality of mounting portions for attaching the fixing member to the main body portion, the mounting portions protruding from one end side of the main body portion with their tip sides bent toward the center of the main body portion, and the fixing member and the water-proofing member can be sandwiched and fixed between the fixing member and the main body portion by inserting the fixing member and the water-proofing member between the plurality of mounting portions and the main body portion.

8. 2. The rust-preventive component for box beams according to claim 1, wherein the main body portion has a flange portion having a relatively large diameter and a protrusion portion having a relatively small diameter protruding from one side of the flange portion.

9. A box girder rust-proofing structure using the box girder rust-proofing member according to any one of claims 1 to 8, A ventilation hole is provided in at least a part of the box girder, A box girder rust prevention structure, characterized in that the box girder rust prevention member is fixed to the outer periphery of the air vent, and the water-blocking member prevents water from entering through the air vent.

10. The main body portion has a flange portion having a relatively large diameter and a protrusion portion having a relatively small diameter protruding from one side of the flange portion, The rust-proofing structure for a box girder according to claim 9, characterized in that the flange portion has a diameter larger than that of the air vent, and the protrusion is inserted into the air vent from the inside of the box girder and fixed thereto.

11. The rust-proof structure for a box beam according to claim 10, characterized in that the tip of the protrusion protrudes a predetermined length from the outer surface of the box beam.

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