JP2019206739A - Internal anticorrosion method of structural steelwork having space inside - Google Patents

Abstract

To provide an internal anticorrosion method of a structural steelwork having a space inside, capable of facilitating a construction work for imparting an anticorrosive effect to an existing structural steelwork.SOLUTION: A first opening 24 and a second opening 28 are provided on a side wall of a strut 20, and an anode material 10 formed by arranging water retention fibers 14 on the outer periphery of a metal rod 12 having a lower potential than the strut 20 is arranged inside the strut 20 from the first opening 24, and fixed in the state where conduction between the metal rod 12 and the strut 20 through the second opening 28 is carried out, and the first opening 24 is blocked with a steel sheet 32.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an internal corrosion prevention method for a steel structure having a space inside, and more particularly to an anticorrosion method suitable for suppressing internal corrosion of a steel structure that is generally configured as a closed space inside.

  Significant corrosion damage may occur on the inner surface, which is a closed part of steel structures such as signs, lighting columns, steel pipe piles, and steel railings in urban viaducts. This damage is often caused mainly by seawater, rainwater containing chlorides such as antifreezing agents, and condensed water that remains in the member for a long time.

  In such a structure, the outer surface is generally subjected to anticorrosion measures such as painting or plating, but it is difficult to apply plating or painting to the inside of an existing structure without any defects. For this reason, various devices are required for anticorrosion measures on the inner surface, which is a closed portion of the steel structure. For example, Patent Document 1 discloses a technique for preventing corrosion inside an existing steel pipe. The technique disclosed in Patent Document 1 cuts a steel pipe, fills the inside with fine particles of metal (base metal) having a base potential lower than that of the steel pipe constituent member, and returns the cut steel pipe to its original state. Is.

  According to such a technique, the metal fine particles filled in the steel tube serve as an anode to cathodic-protect the inner surface of the steel tube, and the anode-dissolved fine particles serve as a hydroxide to form a protective coating, thereby preventing corrosion It is said to increase.

JP 2000-129473 A

  According to the technique disclosed in Patent Document 1, it is considered that there is a certain effect on the corrosion prevention inside the steel structure. However, existing signs, lighting pillars, steel rails in urban viaducts, etc. are equipped with ancillary equipment such as signboards, lighting equipment, sound insulation boards, etc. It may be a large-scale construction such as hanging with a crane, which may lead to a rise in construction costs.

  Therefore, an object of the present invention is to provide an internal corrosion prevention method for a steel structure having a space inside, which can simplify a construction for imparting a corrosion prevention effect to an existing steel structure.

  According to the present invention for achieving the above object, an internal anticorrosion method for a steel structure having a space inside is provided with a first opening and a second opening on a side wall of the steel structure, and more than the steel structure. An anode material having water retaining fibers arranged on the outer periphery of a metal rod having a base potential is arranged from the first opening to the inside of the steel structure, and the metal rod and the steel through the second opening. It fixes in the state which aimed at conduction | electrical_connection with a structure, and the said 1st opening part is block | closed with the steel plate, It is characterized by the above-mentioned.

  Further, in the internal corrosion prevention method for a steel structure having a space inside having the above-described features, the outer periphery of the water retention fiber is compressed before the anode material is disposed inside the steel structure. In addition, after the anode material is disposed inside the steel structure, the compressed state is released, and the water retention fiber is preferably brought into contact with the inner wall of the steel structure. With such a feature, the anode material can be easily loaded into the steel structure. Moreover, when the expansion coefficient of the water retention fiber when the compressed state is released is large, the water retention fiber can be brought into contact with the stepped portion in the steel structure.

  Further, in the internal corrosion prevention method for a steel structure having a space inside having the above-described characteristics, the first opening is closed by the steel plate with an overlap portion with respect to the outer periphery of the first opening. It is desirable to do it in a state. By having such a feature, it is possible to prevent a gap from being generated in the blocked site. Further, it is possible to prevent a decrease in yield strength due to the formation of the first opening.

  In the internal corrosion prevention method for a steel structure having a space inside having the above-described features, an inspection window may be disposed on the steel plate. By having such a feature, it is possible to check the state of the steel structure and the state of the anode material without removing the steel plate.

  Further, in the internal corrosion prevention method for a steel structure having a space inside having the above-described features, the steel structure is cylindrical, and the first opening is formed before the first opening is formed. It is preferable that a reinforcing rib is provided around the formation portion, the first opening is closed, and then the reinforcing rib is removed. By having such a feature, buckling associated with the formation of the first opening can be prevented even in a steel structure having a weight at the top. Moreover, a big change is not given to the external appearance of the steel structure after construction by removing a reinforcement rib after construction.

  Further, in the internal corrosion prevention method for a steel structure having a space inside having the above-described features, the first opening is configured by cutting a semicircular portion of the steel structure formed in a cylindrical shape. Good. With such a feature, it becomes easy to load the anode material into the steel structure.

  Furthermore, in the internal corrosion prevention method for a steel structure having a space in the interior having the above-described features, the water retention fibers constituting the anode material may be disposed so as to contact the inner bottom portion of the steel structure. desirable. By having such a feature, it is possible to obtain an anticorrosive effect at a portion where moisture easily accumulates.

  According to the internal corrosion prevention method for a steel structure having a space inside as described above, it is possible to simplify the construction for providing an anticorrosion effect to the existing steel structure, thereby suppressing the construction cost. can do.

It is a perspective view which shows the structure of the support | pillar which applies the internal corrosion-proof method of the steel structure which has space inside based on 1st Embodiment, and the anode material loaded into a support | pillar. It is a perspective view which shows a mode that the reinforcement rib was installed in the support | pillar. It is a perspective view which shows a mode that the 1st opening part was formed in the support | pillar. It is a figure which shows only the structure of a support | pillar among the AA cross sections in FIG. It is a figure which shows the BB cross section in FIG. 3, and the cross-sectional structure of the anode material with which a support | pillar is loaded. It is a figure which shows the state which loaded the anode material to the support | pillar, and closed the 1st opening part with the steel plate. It is a figure which shows a mode that the reinforcement rib was removed, after closing the 1st opening part with the steel plate. It is a figure which shows the state which provided the inspection window in the steel plate which block | closes a 1st opening part. It is a figure which shows the example of application to an embedded type | mold support | pillar. It is a perspective view which shows a part of external appearance structure of the wall rail which applies the internal corrosion prevention method of the steel structure which has space inside which concerns on 2nd Embodiment. It is a perspective view which shows the structure of the anode material comprised by arrange | positioning a some metal rod in parallel on the sheet | seat of a water retention fiber. It is a perspective view which shows the decomposition | disassembly state of the anode material shown in FIG. It is sectional drawing which shows the state which charged the balustrade with the anode material, and closed the 1st opening part with the steel plate.

  Hereinafter, an embodiment according to an internal corrosion prevention method for a steel structure having a space inside the present invention will be described in detail with reference to the drawings. The embodiment shown below is a part of an embodiment suitable for carrying out the internal corrosion prevention method for a steel structure having a space inside the present invention, and each element is within a range not departing from the function thereof. Even if the form and the order of construction are changed, it can be regarded as a part of the present invention.

[First Embodiment]
The internal corrosion prevention method (hereinafter simply referred to as internal corrosion prevention method) of a steel structure having a space inside according to the present embodiment is a steel structure as a support 20 as shown in FIG. This is done by loading the anode material 10 as shown in FIG. Hereinafter, the configuration of each element and a specific method will be described.

[Support]
The column 20 as a steel structure may be a column of a structure having a larger diameter in addition to a column used for street lamps, signboards, road signs, and the like. The support column 20 shown in FIG. 1 is a type fixed to a base plate 22 for fixing, and the base plate 22 is fixed to a concrete foundation (ground) via bolts or the like.

[Anode material]
The anode material 10 used in this embodiment is configured based on a metal rod 12 and water retention fibers 14. The metal rod 12 may serve as a sacrificial anode and may be made of a metal having a lower potential than the support column 20 as a steel structure to be subjected to anticorrosion treatment. When the support 20 that is a steel structure is made of iron (Fe), the metal rod 12 may be aluminum (Al), zinc (Zn), aluminum alloy, magnesium alloy, or the like. In consideration of ease of processing and raw material costs, it is desirable to use an aluminum-zinc alloy (Al-Zn) or the like.

The water retention fiber 14 may be any member having water retention, and may be, for example, cloth, paper, knitted fabric, and non-woven fabric. Further, the water retention fiber 14 can include a fiber having a hydrophilic functional group. Specifically, any material having a hydrophilic functional group such as —SO ₃ H, —COOH, —NH ₃ , —CONH ₂ , —CHO, —SH, —OH in the fiber or on the fiber surface may be used. This is because the fibers having such a composition can retain moisture in the fibers or between the fibers. Examples of the fiber having a hydrophilic functional group include rayon, cotton, vinylon, nylon, wool, and acrylate.

  The anode material 10 used in the embodiment is configured by disposing the water retention fibers 14 having the above-described configuration on the outer periphery of the metal rod 12 having the above-described configuration. The arrangement | positioning means of the water retention fiber 14 is not specifically limited, What is necessary is just to wind the sheet-like water retention fiber 14 around the outer periphery of the metal rod 12, as shown in FIG.1 and FIG.5.

  When the anode material 10 having such a configuration is used, the water retention fiber 14 is impregnated with an electrolytic solution. The electrolyte may be any one that generates a corrosion-proof current between the steel structure to be protected against corrosion and the metal rod, that is, one that causes the movement of ions, but is in a space within the existing steel structure. In this case, rainwater and moisture in the atmosphere are responsible for the electrolyte function.

  In addition, the metal rod 12 of the anode material 10 according to the embodiment is connected to the column 20 as a steel structure by the conductive member 16. The conductive member 16 may be a flexible conductor or the like, but in this embodiment, the conductive member 16 is an element that plays a role as a support for positioning the anode material 10 by being fixed to the support column 20. .

[Application to steel structures]
Next, a description will be given of an internal corrosion prevention method in which the anode material 10 having the above-described features is installed on a support column 20 that is a steel structure. First, the 1st opening part 24 (refer FIG. 2, FIG. 3) for loading the anode material 10 is formed in the lower end part of the support | pillar 20, or a lower end part vicinity. Here, before the first opening 24 is formed, one or more reinforcing ribs 26 are arranged on the outer periphery of the support column 20 as shown in FIG. 2 (three in the example shown in FIG. 2). By arranging the reinforcing ribs 26, it is possible to prevent the column 20 from buckling due to the weight of the upper half when the first opening 24 is formed. The arrangement of the reinforcing ribs 26 is preferably in the radial direction of the column 20 so as to be read from the column cross section shown in FIG. 4 so as to support the weight of the upper half of the column (not shown).

  After the reinforcing ribs 26 are arranged, as shown in FIG. 3, the side surfaces of the support pillars 20 are cut to form the first openings 24. When the column 20 is cylindrical, the first opening 24 may have an opening width that is about half of the column 20, that is, an opening width that is about the diameter of the inner diameter of the column 20, as shown in FIG. 4. This is because the anode material 10 can be easily loaded. Further, before and after the formation of the first opening 24, the second opening 28 for fixing the anode material 10 is formed on the side surface of the support column 20. Here, the first opening 24 is an opening for loading the anode material 10 to the support column 20. On the other hand, the second opening 28 is an opening for inserting and fixing the conductive member 16. Therefore, the second opening 28 is an extremely small opening compared to the first opening 24.

  Next, as shown in FIG. 5, the anode material 10 is loaded and arranged from the first opening 24 into the support 20. At this time, the water retention fibers 14 arranged on the outer periphery of the metal rod 12 are densely arranged so as to come into contact with the inner wall of the column 20 when the anode material 10 is arranged inside the column 20. By using the water retaining fiber 14 as the member disposed between the metal rod 12 and the support column 20, the flexible fiber is well adhered to both members, and the anticorrosion effect can be enhanced. It is. In addition, although the arrangement | positioning range of the water retention fiber 14 is not limited, it becomes possible to show the anticorrosion effect in a wide range by setting it as the range which covers the metal rod 12 to a longitudinal direction. Here, as shown in FIG. 5, the anode material 10 can be brought into contact with the lower end portion of the column 20 where moisture easily accumulates by disposing the water retaining fiber 14 downward. Become.

  The conductive member 16 is disposed so as to penetrate the second opening 28, and is fixed in a state in which conductivity with the support column 20 is ensured via a nut 30 (see FIG. 6) or the like. For this reason, the second opening 28 is closed together with the fixing of the conductive member 16. As described above, in this embodiment, the conductive member 16 serves as a support for the metal rod 12. For this reason, the anode member 10 including the metal rod 12 is positioned inside the support 20 by fixing the conductive member 16 to the support 20 via the second opening 28.

  After positioning and fixing of the anode material 10, as shown in FIG. 6, the first opening 24 is closed with the steel plate 32. The steel plate 32 is a plate member having an area that is slightly larger than the opening area of the first opening 24. For this reason, the blockage by the steel plate 32 is in a state of having an overlap portion with respect to the outer periphery of the first opening 24. There are various methods of closing with the steel plate 32. For example, a method of joining the steel plate 32 to the support 20 by welding can be employed.

  In this way, with the anode material 10 sealed inside the support column 20, the metal rod 12 is placed between the support column 20 and the metal rod 12 as an anode, An anticorrosion current using the column 20 as a cathode is generated. Thereby, an oxidation reaction occurs in the metal rod 12 and a reduction reaction occurs in the support column 20, and it becomes possible to prevent corrosion of the inner wall surface of the support column 20. In addition, as for the electrolyte solution here, rain water and the moisture in air | atmosphere will have the effect | action as mentioned above.

  After the closing of the first opening 24 by the steel plate 32 is completed, the reinforcing ribs 26 attached to the outer periphery of the support column 20 are removed as shown in FIG. This is because by closing the first opening 24 with the steel plate 32, the strength of the column 20 is restored to its original state, and there is no possibility that buckling or the like due to the weight of the upper half portion will occur in the column.

  Thus, according to the internal anticorrosion method according to the present embodiment, it is not necessary to cut unnecessary members for the construction for providing the anticorrosion effect to the existing steel structure. For this reason, a large-scale device such as a crane that supports the cut upper half portion is not required, and the construction can be simplified. Therefore, the construction cost can be suppressed.

  Further, in the above description, it has been described that the anode material 10 is loaded and arranged in the first opening 24. However, before the anode material 10 is disposed inside the support column 20, the outer periphery of the water retention fiber 14 constituting the anode material 10 may be in a compressed state. By setting it as such a structure, the external shape of the anode material 10 can be reduced in size. Therefore, it becomes easy to arrange the anode material 10 inside the column 20. Further, after the anode material 10 is disposed inside the support column 20, the compressed state of the water retention fiber 14 is released, and the water retention fiber 14 is preferably brought into contact with the inner wall of the support column 20. If the expansion of the water retaining fiber 14 after release of the compressed state is large, even if there is a step between the inner wall of the support column 20 and the steel plate 32 closing the first opening 24, the water retaining fiber 14 is also attached to the steel plate 32. Can be contacted.

  Moreover, you may make it provide the inspection window 34 in the steel plate 32 which plugs up the 1st opening part 24, as shown in FIG. This is because by making the inspection window 34 openable and closable, the state of the anode material 10 and the state inside the column 20 can be inspected without removing the steel plate 32.

  In addition, in the said embodiment, the support | pillar 20 demonstrated that it was being fixed to the foundation via the baseplate 22. In FIG. However, in the case of the type in which the support column 20 is embedded in the foundation, as shown in FIG. 9, the anode material 10 has a length that spans both the underground portion and the ground portion from the first opening 24, and is loaded inside. Good.

[Second Embodiment]
Next, an internal corrosion prevention method for a steel structure in the case where the anode material having the above-described features is applied to a large structure such as a steel bridge of a viaduct will be described.
The steel structure of the present embodiment is a box having a rectangular cross section, such as a viaduct 40 of a viaduct as shown in FIG. When a steel structure is such a form, the 1st opening part 42 is formed in a part of side wall of the balustrade 40. As shown in FIG. Since there are incidental objects such as a sound insulation plate 44 as shown in FIG. 13 at the top of the rail 40, construction such as removal of the sound insulation plate 44 becomes unnecessary by providing an opening in the side wall. Here, unlike the 1st opening part formed in the support | pillar 20 described as 1st Embodiment, the 1st opening part 42 provided in the side wall of the rail 40 is not over the range which reduces the intensity | strength of a side wall extremely. There is no need to provide the reinforcing rib 26.

  The anode material 10A to be loaded in the inside of the rail 40 having a rectangular cross section may be one in which the water retaining fiber 14 is wound around the metal rod 12 like the anode material 10 according to the first embodiment. As shown in FIGS. 11 and 12, a plurality of metal rods 12 arranged in parallel may be sandwiched between water retention fibers 14. Here, the water-retaining fibers that sandwich the metal rod 12 may be a pair of sheet-like members, but are configured by laminating a plurality of sheet-like members as shown in an exploded perspective view in FIG. It may be.

  Even with the anode material having such a configuration, as shown in FIG. 13, the anode material 10 </ b> A is loaded through the first opening 24 and is closed by the steel plate 46, so that the support 20 according to the first embodiment Similarly, it is possible to simplify the construction for imparting the anticorrosion effect to the existing steel structure. Therefore, the construction cost can be suppressed.

  In addition, when arrange | positioning the anode material 10 and 10A provided with the water retention fiber 14 with respect to a steel structure like the said embodiment, before arrange | positioning the anode material 10 and 10A, a base material is put inside a steel structure. Adjustments should be made. The substrate adjustment may be any work that removes rust and dirt adhering to the inside of the steel structure. According to the base adjustment in the steel structure, the anticorrosion effect can be enhanced.

10, 10A ......... Anode material, 12 ......... Metal rod, 14 ......... Water retentive fiber, 16 ......... Conductive member, 20 ......... Post, 22 ......... Base plate, 24 ......... First Opening, 26 ......... Reinforcing rib, 28 ......... Second opening, 30 ......... Nut, 32 ......... Steel, 34 ......... Inspection window, 40 ...... Rank, 42 ......... First Opening, 44 ..... Sound insulation board, 46 .... Steel plate.

Claims (7)

Providing a first opening and a second opening on the side wall of the steel structure;
An anode material in which water retaining fibers are arranged on the outer periphery of a metal rod having a lower potential than the steel structure is arranged from the first opening to the inside of the steel structure, and through the second opening. Fix in a state where conduction between the metal rod and the steel structure is achieved,
An internal corrosion protection method for a steel structure having a space inside, wherein the first opening is closed with a steel plate. Before placing the anode material inside the steel structure, leave the outer periphery of the water retention fiber in a compressed state,
2. The space according to claim 1, wherein after the anode material is disposed inside the steel structure, the compressed state is released, and the water retention fiber is brought into contact with an inner wall of the steel structure. A method for internal corrosion protection of steel structures having   The steel having a space inside according to claim 1 or 2, wherein the first opening is closed by the steel plate in a state where an overlap portion is provided with respect to an outer periphery of the first opening. Internal anticorrosion method for structures.   The internal corrosion prevention method for a steel structure having a space inside according to any one of claims 1 to 3, wherein an inspection window is arranged on the steel plate. The steel structure is cylindrical, and before forming the first opening, a reinforcing rib is applied around the first opening forming part,
The internal corrosion prevention method for a steel structure having a space inside according to any one of claims 1 to 4, wherein the reinforcing rib is removed after the first opening is closed.   6. The internal corrosion protection of a steel structure having a space inside according to claim 5, wherein the first opening is configured by cutting a semicircular portion of the steel structure formed in a cylindrical shape. Method.   The steel structure having a space inside according to any one of claims 1 to 6, wherein the water retention fibers constituting the anode material are arranged so as to contact an inner bottom portion of the steel structure. Internal anticorrosion method of things.

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