Steel parts

Abstract

The present invention provides a steel member that can suppress damage to the corrosion sensor when driving a steel member equipped with a corrosion sensor into the ground. [Solution] The steel member (100) is driven into the ground to reinforce the ground. The steel member (100) comprises a corrosion sensor (1) attached to a part of its surface and a protrusion (2) provided on the part of the surface located in the direction of driving relative to the corrosion sensor (1).

Description

Technical Field

[0001] The present disclosure relates to steel members, and more particularly to steel members driven into the ground to reinforce the ground.

Background Art

[0002] In recent years, from the viewpoints of disaster prevention and mitigation, there has been a strong demand for strengthening the ground of embankments, newly constructed residential areas, etc., which are filled with soil. As a technology to meet this demand, a technology of driving and installing steel members, specifically steel sheet piles, into the ground has attracted attention. In promoting this technology, it is important to monitor the corrosion status of the steel members installed in the ground for maintenance management and life prediction.

[0003] For example, Japanese Patent No. 5515680 (Patent Document 1) discloses a technology for monitoring the durability of heavily anti-corrosion coated steel materials. In the technology of this Patent Document 1, a plurality of parts that penetrate in the plate thickness direction and are insulated from the surroundings by an insulating material are provided in a part of the steel material, and coating conductors are respectively attached to the end faces on the side of the steel material surface on the non-heavily anti-corrosion coating layer side at at least two of the plurality of parts, and the attachment parts of the coating conductors on the end faces are covered with an insulating material. Then, the electrical resistance between the coating conductors is continuously measured, or the coating conductors are short-circuited through a non-resistance ammeter to continuously measure the corrosion current, or the AC impedance between the coating conductors is continuously measured. According to the technology of Patent Document 1, it is possible to detect that the heavily anti-corrosion coating layer has peeled off from the steel material surface.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The technology described in Patent Document 1 is a technology for monitoring the peeling of the heavy corrosion-resistant coating layer in heavy corrosion-resistant coated steel materials used in river and marine structures, and does not relate to steel members installed in the ground, nor is it a technology for monitoring the corrosion status of steel members. When monitoring the corrosion status of steel members installed in the ground, one might consider first attaching corrosion sensors to the surface of the steel member, and then driving the steel member with the corrosion sensors into the ground. However, when the steel member with the corrosion sensors is driven into the ground, there is a high possibility that the corrosion sensors will come into contact with the hard soil of the ground and be damaged.

[0006] The purpose of this disclosure is to provide a steel member that can suppress damage to the corrosion sensor when the steel member with the corrosion sensor is driven into the ground. [Means for solving the problem]

[0007] The steel member relating to this disclosure is driven into the ground to reinforce the ground. The steel member comprises a corrosion sensor attached to a part of its surface and a protrusion provided on the part of the surface located in the direction of driving relative to the corrosion sensor. [Effects of the Invention]

[0008] According to the steel member described herein, damage to the corrosion sensor can be suppressed when the steel member with the corrosion sensor is driven into the ground. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view of a steel member according to the first embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view of the steel member shown in Figure 1. [Figure 3] Figure 3 is a perspective view of the steel member according to the second embodiment. [Figure 4] Figure 4 is an enlarged cross-sectional view of the steel member shown in Figure 3. [Figure 5] Figure 5 is an enlarged cross-sectional view of the steel member according to the third embodiment. [Modes for carrying out the invention]

[0010] The steel member according to the embodiment of this disclosure is driven into the ground to reinforce the ground. The steel member comprises a corrosion sensor and a protrusion. The corrosion sensor is attached to a part of the surface of the steel member. The protrusion is provided on the surface of the steel member in a part located in the direction of driving relative to the corrosion sensor (first configuration).

[0011] The steel member according to the first configuration is equipped with a corrosion sensor attached to a part of its surface. This steel member with the corrosion sensor is further equipped with a protrusion on the surface of the steel member that is located in the direction of driving relative to the corrosion sensor. In this case, when the steel member with the corrosion sensor is driven into the ground, the protrusion penetrates the ground before the corrosion sensor. As a result, the protrusion comes into contact with the hard soil of the ground before the corrosion sensor, breaking up and pushing aside the hard soil around the protrusion. Therefore, with the steel member according to the first configuration, when the steel member with the corrosion sensor is driven into the ground, the corrosion sensor does not come into contact with the hard soil, and as a result, damage to the corrosion sensor can be suppressed.

[0012] In the above-described steel member, it is preferable that the height dimension of the protrusion from the surface of the steel member is 0.5 times or more the height dimension of the corrosion sensor from the surface of the steel member (second configuration). In the second configuration, when the steel member with the corrosion sensor is driven into the ground, the area of ​​soil that is disturbed by the protrusion is sufficient for the corrosion sensor.

[0013] The steel member preferably includes a flat plate portion. In this case, the surface to which the corrosion sensor is attached and which has a protrusion may be one of the two surfaces of the flat plate portion (third configuration). In the third configuration, steel sheet piles, specifically U-shaped steel sheet piles, hat-shaped steel sheet piles, straight steel sheet piles, Z-shaped steel sheet piles, and H-shaped steel sheet piles, can be used as the steel member.

[0014] The steel member according to the first configuration or the second configuration may include a cylindrical portion. In this case, the surface on which the corrosion sensor is attached and the convex portion is provided may be one of the two surfaces of the cylindrical portion (the fourth configuration). In the fourth configuration, steel pipe piles and steel sheet piles can be used as the steel member.

[0015] In the steel member, preferably, the convex portion is formed of a lump material different from the steel member, and the lump material is joined to the above surface of the steel member (the fifth configuration). In the fifth configuration, the convex portion can be provided on the steel member at a low cost and easily.

[0016] In the steel member according to any one of the first to fourth configurations, the convex portion may be uniform with the steel member (the sixth configuration). In the sixth configuration, the convex portion can be firmly provided on the steel member.

[0017] In the steel member, preferably, the corrosion sensor is an electric resistance type corrosion sensor (the seventh configuration).

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The same or corresponding components in each figure are denoted by the same reference numerals, and redundant descriptions will not be repeated.

[0019] <First Embodiment> [Steel Member with Corrosion Sensor] Referring to FIGS. 1 and 2, the configuration of the steel member 100 according to the first embodiment will be described. FIG. 1 is a perspective view of the steel member 100. Referring to FIG. 1, the steel member 100 is a steel sheet pile. Specifically, the steel member 100 is a hat-shaped steel sheet pile. The steel member 100 is driven into the ground to reinforce the ground. The ground into which the steel member 100 is driven is a fill such as a levee or a reclaimed housing site. The steel member 100 extends in one direction. The extending direction of the steel member 100 corresponds to the driving progress direction.

[0020] The steel member 100, which is a hat-shaped steel sheet pile, has a web 101, two flanges 102, two arms 103, and two joints 104. The web 101, each flange 102, each arm 103, and each joint 104 all extend in one direction, that is, the driving progress direction. The web 101 is a base portion and has a flat shape. Therefore, the web 101 is a flat plate portion. The flange 102 is connected to the side edge of the web 101. The flange 102 also has a flat shape. Therefore, the flange 102 is a flat plate portion. The arm 103 is connected to the side edge of the flange 102. The joint 104 has a hook shape and is provided on the side edge of the arm 103. In addition, in the joint 104 shown in FIG. 1, the illustration of the hook shape is omitted.

[0021] The web 101, which is a flat plate portion, has an outer surface 1011 and an inner surface 1012 (see FIG. 2) as both sides. The outer surface 1011 means the surface that is exposed to the outside when the hat-shaped steel sheet pile (steel member 100) is placed on the ground with the web 101 positioned on the upper side. On the other hand, the inner surface 1012 means the surface that is hidden from the outside in this state.

[0022] The steel member 100 includes a corrosion sensor 1 and a convex portion 2. The corrosion sensor 1 is attached to a part of the surface of the steel member 100. Specifically, the corrosion sensor 1 is attached to a part of one of the two surfaces of the web 101, which is a flat plate portion. More specifically, the corrosion sensor 1 is attached to a part of the outer surface 1011 or the inner surface 1012 of the web 101. In the example shown in FIG. 1, the corrosion sensor 1 is attached to a part of the outer surface 1011 of the web 101. However, the corrosion sensor 1 may be attached to the inner surface 1012 of the web 101. That is, the surface of the steel member 100 to which the corrosion sensor 1 is attached is one of the two surfaces (the outer surface 1011 or the inner surface 1012) of the web 101, which is a flat plate portion.

[0023] The corrosion sensor 1 is substantially plate-shaped. The corrosion sensor 1 only needs to be stably attached to the surface of the steel member 100 while being electrically insulated from the steel member 100, and the method of attaching the corrosion sensor 1 to the steel member 100 is not particularly limited. For example, the corrosion sensor 1 is fastened to the steel member 100 by bolts. The corrosion sensor 1 may also be bonded to the steel member 100 by an adhesive (e.g., epoxy resin, urethane resin, modified silicone).

[0024] Figure 2 is an enlarged cross-sectional view of the steel member 100 shown in Figure 1. Figure 2 shows a longitudinal section of the steel member 100 including the portion to which the corrosion sensor 1 is attached. Note that the corrosion sensor 1 and the protrusion 2 are exaggerated in Figures 1 and 2.

[0025] Referring to Figures 1 and 2, in this embodiment, the corrosion sensor 1 is an electrical resistance type corrosion sensor. In this case, the corrosion sensor 1 includes a metal piece 11, an insulator 12, and two insulated conductors 13 (see Figure 1).

[0026] The metal piece 11 has an elongated plate shape and is held by an insulator 12. The material of the insulator 12 is, for example, epoxy resin. The surface of the metal piece 11 is exposed to the outside and is not covered by the insulator 12. The metal piece 11 is made of the same material as the steel member 100. Carbon steel can be used as the metal piece 11. The metal piece 11 serves as a sample to show the corrosion status of the steel member 100.

[0027] The two insulated wires 13 are each connected to the metal piece 11 on its back surface. Specifically, one insulated wire 13 is connected to one end of the metal piece 11, and the other insulated wire 13 is connected to the other end of the metal piece 11. Each insulated wire 13 is drawn out in the opposite direction to the direction in which the steel member 100 is driven in. Each insulated wire 13 is bonded to the steel member 100 with an adhesive (e.g., epoxy resin). The corrosion sensor 1 in this embodiment is an electrical resistance type corrosion sensor, and the electrical resistance is measured using the four-terminal method. The two insulated wires 13 described above are wires for conducting current through the metal piece 11. In Figure 1, the illustration of the insulated wire for measuring voltage is omitted.

[0028] The protrusion 2 is provided on the surface of the steel member 100 in the direction of driving in relation to the corrosion sensor 1. In other words, the protrusion 2 is not provided on the surface of the steel member 100 in the direction opposite to the direction of driving in relation to the corrosion sensor 1. For this reason, similar to the corrosion sensor 1, the protrusion 2 is provided on a part of one of the two surfaces of the web 101. More specifically, the protrusion 2 is attached to a part of the outer surface 1011 or the inner surface 1012. In the examples shown in Figures 1 and 2, the protrusion 2 is attached to a part of the outer surface 1011 of the web 101, similar to the corrosion sensor 1. However, the corrosion sensor 1 may also be attached to the inner surface 1012 of the web 101, in which case the protrusion 2 is attached to the inner surface 1012 of the web 101. That is, the surface of the steel member 100 to which the corrosion sensor 1 is attached and to which the protrusion 2 is provided is one of the two surfaces (outer surface 1011 or inner surface 1012) of the flat web 101.

[0029] The protrusion 2 only needs to be provided in a portion located in the direction of driving relative to the corrosion sensor 1, and the distance d (see Figure 2) between the corrosion sensor 1 and the protrusion 2 in the direction of driving is not particularly limited. This distance d is, for example, 1.0 mm to 100 mm.

[0030] Referring to Figure 2, it is preferable that the height dimension h2 of the protrusion 2 from the surface of the steel member 100, i.e., the outer surface 1011 of the web 101, is 0.5 times or more the height dimension h1 of the corrosion sensor 1 from the surface of the steel member 100, i.e., the outer surface 1011 of the web 101. The height dimension h1 of the corrosion sensor 1 refers to the maximum height dimension of the corrosion sensor 1. Similarly, the height dimension h2 of the protrusion 2 refers to the maximum height dimension of the protrusion 2. The height dimension h1 of the corrosion sensor 1 is, for example, 0.5 mm to 50 mm.

[0031] Referring to Figures 1 and 2, in this embodiment, the protrusion 2 is made of a separate block material from the steel member 100. Specifically, the block material constituting the protrusion 2 is a rod. More specifically, the block material constituting the protrusion 2 is a rectangular prism-shaped rod. The protrusion 2, made of the block material, is joined to the surface of the steel member 100, i.e., the outer surface 1011 of the web 101. The material of the block material (protrusion 2) is not particularly limited. A block of carbon steel can be used as this protrusion 2.

[0032] In this embodiment, the block material constituting the protrusion 2, i.e., the rod material, is arranged along the surface of the steel member 100 so as to extend in a direction perpendicular to the direction of driving the steel member 100. However, the rod material may also be arranged along the surface of the steel member 100 so as to extend in a direction inclined with respect to the direction of driving the steel member 100.

[0033] The block material, i.e., the rod material, that constitutes the protrusion 2 may be a cylindrical rod. Furthermore, the shape of the protrusion 2 made up of the block material is not particularly limited and may be a shape other than a rod.

[0034] The protrusion 2, which is made of a solid material, only needs to be firmly joined to the surface of the steel member 100, and the method of joining the protrusion 2 to the steel member 100 is not particularly limited. For example, the protrusion 2 is fastened to the steel member 100 by bolts. The protrusion 2 may also be welded to the steel member 100. The protrusion 2 may also be bonded to the steel member 100 by an adhesive (e.g., epoxy resin).

[0035] The steel member 100 with the corrosion sensor 1 configured in this way is driven into the ground by methods such as impact driving, vibro-hammer driving, and press-in driving. This installs the steel member 100 in the ground. In short, the steel member 100 is driven into the ground. After the steel member 100 is installed in the ground, each insulated wire 13 of the corrosion sensor 1 is connected to a measuring device. The measuring device intermittently or continuously applies a direct current to the metal piece 11 of the corrosion sensor 1 via the insulated wire 13 to measure the electrical resistance of the metal piece 11. The corrosion status of the metal piece 11 can be monitored by the change in electrical resistance over time, and the corrosion status of the steel member 100 can be monitored from the corrosion status of the metal piece 11. This is because the metal piece 11 is integrated with the steel member 100, and the corrosion status of the metal piece 11 corresponds to the corrosion status of the steel member 100. Although not shown in the diagram, it is also possible to measure the electrical resistance of the metal piece 11 with high accuracy by monitoring its temperature using, for example, a thermocouple, thereby taking into account the effects of temperature changes.

[0036] [effect] The steel member 100 of this embodiment is equipped with a corrosion sensor 1. The corrosion sensor 1 is attached to a part of the surface of the steel member 100, specifically to a part of the outer surface 1011 of the web 101. The steel member 100 with the corrosion sensor 1 is further equipped with a protrusion 2. The protrusion 2 is provided on the surface of the steel member 100, specifically on a part of the outer surface 1011 of the web 101 that is located in the direction of driving relative to the corrosion sensor 1. In this case, when the steel member 100 with the corrosion sensor 1 is driven into the ground, the corrosion sensor 1 is located behind the protrusion 2, and the protrusion 2 penetrates the ground before the corrosion sensor 1. Therefore, the protrusion 2 comes into contact with the hard soil of the ground before the corrosion sensor 1, and pushes aside the hard soil around the protrusion 2 while breaking it up. Thus, with the steel member 100, when the steel member 100 with the corrosion sensor 1 is driven into the ground, the corrosion sensor 1 does not come into contact with hard soil, but rather with loose soil. As a result, damage to the corrosion sensor 1 can be suppressed.

[0037] In this embodiment, the height dimension h2 of the protrusion 2 from the surface of the steel member 100, specifically the outer surface 1011 of the web 101, is 0.5 times or more the height dimension h1 of the corrosion sensor 1 from the surface of the steel member 100, specifically the outer surface 1011 of the web 101. In this case, when the steel member 100 with the corrosion sensor 1 is driven into the ground, the area of ​​soil that is disturbed by the protrusion 2 is sufficient for the corrosion sensor 1. More preferably, the height dimension h2 of the protrusion 2 is equal to or greater than the height dimension h1 of the corrosion sensor 1. The upper limit of the height dimension h2 of the protrusion 2 is not particularly limited, but it is preferably 10 times the height dimension h1 of the corrosion sensor 1. If the height dimension h2 of the protrusion 2 is 10 times or more the height dimension h1 of the corrosion sensor 1, the contact state between the metal piece 11 of the corrosion sensor 1 and the soil tends to become unstable, and there is a risk that the corrosion status of the steel member 100 cannot be properly monitored.

[0038] The steel member 100 in this embodiment is a hat-shaped steel sheet pile and includes a flat plate portion, specifically a web 101. The surface to which the corrosion sensor 1 is attached and which has a protrusion 2 is one of the two surfaces (outer surface 1011 or inner surface 1012) of the web 101, which is the flat plate portion. However, in the steel member 100 of the hat-shaped steel sheet pile, the corrosion sensor 1 and the protrusion 2 may be provided on one of the two surfaces (outer surface or inner surface) of the flange 102. Furthermore, the steel member 100 in this embodiment only needs to include a flat plate portion, and in this case, other steel sheet piles, specifically U-shaped steel sheet piles, straight steel sheet piles, Z-shaped steel sheet piles, and H-shaped steel sheet piles, can be used as the steel member 100.

[0039] In the steel member 100 of this embodiment, the protrusion 2 is made of a separate block material from the steel member 100, and the block material is joined to the surface of the steel member 100. The block material can be procured relatively inexpensively. Therefore, the protrusion 2 can be provided on the steel member 100 inexpensively and easily. In particular, if the block material constituting the protrusion 2 is a rod, specifically a square rod or a round rod, and its material is carbon steel, the procurement of the block material can be made even easier.

[0040] <Second Embodiment> The configuration of the steel member 100A according to the second embodiment will be described with reference to Figures 3 and 4. Figure 3 is a perspective view of the steel member 100A. Figure 4 is an enlarged cross-sectional view of the steel member 100A shown in Figure 3. The steel member 100A differs from the steel member 100 of the first embodiment in the configuration of the protrusion 2A.

[0041] In this embodiment, as in the first embodiment, the protrusion 2A is made of a block material. The block material constituting the protrusion 2A is a square bar. This block material is positioned along the surface of the steel member 100A, specifically the outer surface 1011 of the web 101, so as to extend in a direction perpendicular to the driving direction of the steel member 100A. In this embodiment, the front surface 21A of the protrusion 2A is inclined so as it moves away from the outer surface 1011 of the web 101 in the direction opposite to the driving direction. That is, the front surface 21A of the protrusion 2A is a tapered surface. The front surface 21A is the surface of the protrusion 2A that precedes the steel member 100A when it is driven into the ground.

[0042] According to the steel member 100A, when the steel member 100A with the corrosion sensor 1 is driven into the ground, the front surface 21A of the protrusion 2 comes into contact with the hard soil of the ground. The soil that comes into contact with the front surface 21A is broken down and moves away from the web 101 along the front surface 21A. In this case, the amount of soil that comes into contact with the corrosion sensor 1 is reduced.

[0043] <Third Embodiment> Referring to Figure 5, the configuration of the steel member 100B according to the third embodiment will be described. Figure 5 is an enlarged cross-sectional view of the steel member 100B. Figure 5 shows a longitudinal section of the steel member 100B including the portion to which the corrosion sensor 1 is attached. The steel member 100B differs from the steel members 100 and 100A of the first and second embodiments in the configuration of the protrusion 2B.

[0044] In this embodiment, the steel member 100B is a steel pipe pile. The steel member 100B, being a steel pipe pile, has a cylindrical shape. Therefore, the steel member 100B includes a cylindrical portion 105. A steel sheet pile may also be used as the steel member 100B.

[0045] The cylindrical portion 105 has an outer circumferential surface 1051 and an inner circumferential surface 1052 as its two surfaces. The outer circumferential surface 1051 refers to the surface located radially outward of the cylindrical portion 105 of the steel pipe pile or steel pipe sheet pile (steel member 100B). On the other hand, the inner circumferential surface 1052 refers to the surface located radially inward of the cylindrical portion 105.

[0046] The corrosion sensor 1 is attached to a part of the surface of the steel member 100B. Specifically, the corrosion sensor 1 is attached to a part of one of the two surfaces of the cylindrical portion 105. More specifically, the corrosion sensor 1 is attached to a part of the outer circumferential surface 1051 or the inner circumferential surface 1052 of the cylindrical portion 105. In the example shown in Figure 5, the corrosion sensor 1 is attached to a part of the outer circumferential surface 1051 of the cylindrical portion 105. However, the corrosion sensor 1 may also be attached to the inner circumferential surface 1052 of the cylindrical portion 105. That is, the surface of the steel member 100B to which the corrosion sensor 1 is attached is one of the two surfaces of the cylindrical portion 105 (outer circumferential surface 1051 or inner circumferential surface 1052).

[0047] The protrusion 2B is provided on the surface of the steel member 100B in the direction of driving in relation to the corrosion sensor 1. Therefore, similar to the corrosion sensor 1, the protrusion 2B is provided on a part of one of the two surfaces of the cylindrical portion 105. More specifically, the protrusion 2B is attached to a part of the outer circumferential surface 1051 or the inner circumferential surface 1052. In the example shown in Figure 5, the protrusion 2B is attached to a part of the outer circumferential surface 1051 of the cylindrical portion 105, similar to the corrosion sensor 1. However, the corrosion sensor 1 may also be attached to the inner circumferential surface 1052 of the cylindrical portion 105, in which case the protrusion 2B is attached to the inner circumferential surface 1052 of the cylindrical portion 105. That is, the surface of the steel member 100B to which the corrosion sensor 1 is attached and to which the protrusion 2B is provided is one of the two surfaces of the cylindrical portion 105 (outer circumferential surface 1051 or inner circumferential surface 1052).

[0048] In this embodiment, the protrusion 2B is uniform with the steel member 100B. Specifically, in the example shown in Figure 5, when the protrusion 2B protrudes from the outer circumferential surface 1051 of the cylindrical portion 105, the protrusion 2B is the ring-shaped enlarged portion of the cylindrical portion 105 of the steel member 100B. In this case, during the manufacturing process of the steel member 100B, the protrusion 2 can be formed by pressing a tool against the inner circumferential surface 1052 of the cylindrical portion 105. When the protrusion 2B protrudes from the inner circumferential surface 1052 of the cylindrical portion 105, the protrusion 2B is the ring-shaped reduced diameter portion of the cylindrical portion 105 of the steel member 100B. In this case, during the manufacturing process of the steel member 100B, the protrusion 2 can be formed by pressing a tool against the outer circumferential surface 1051 of the cylindrical portion 105.

[0049] With the steel member 100B, the protrusion 2B can be firmly attached to the steel member 100B, that is, the cylindrical portion 105. In this case, there is no possibility of the protrusion 2B falling off.

[0050] However, in the steel member 100B, the protrusions 2, 2A as in the first and second embodiments may be applied. That is, in the steel member 100B, the protrusion 2B may be made of a different material from the cylindrical portion 105.

[0051] Furthermore, in the steel members 100 and 100A, a protrusion 2B as in the third embodiment may be applied. That is, in the steel members 100 and 100A, the protrusions 2 and 2A may be uniform with the flat plate portion.

[0052] While embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from its spirit. For example, the type of corrosion sensor 1 is not particularly limited. That is, the corrosion sensor 1 is not limited to an electrical resistance type corrosion sensor. An AC impedance type corrosion sensor can be used as the corrosion sensor 1, and an ACM (Atmospheric Corrosion Monitor) type corrosion sensor may also be used. In practice, it is preferable that the corrosion sensor 1 is an electrical resistance type corrosion sensor. [Explanation of Symbols]

[0053] 100, 100A, 100B: Steel members 1: Corrosion sensor 2,2A,2B: Convex part

Claims

1. A steel member driven into the ground to reinforce the ground, A corrosion sensor attached to a part of the surface, A steel member comprising a protrusion provided on the surface in a portion located in the direction of driving with respect to the corrosion sensor.

2. A steel member according to claim 1, A steel member wherein the height dimension of the protrusion from the surface is 0.5 times or more the height dimension of the corrosion sensor from the surface.

3. A steel member according to claim 1, Including the flat portion, A steel member on which the corrosion sensor is attached and on which the protrusion is provided, wherein the surface is one of the two surfaces of the flat plate portion.

4. A steel member according to claim 1, Including the cylindrical part, A steel member on which the corrosion sensor is attached and on which the protrusion is provided, the surface being one of the two surfaces of the cylindrical portion.

5. A steel member according to claim 1, The steel member wherein the protrusion is made of a separate block material from the steel member, and the block material is joined to the surface.

6. A steel member according to claim 1, The aforementioned protrusion is uniform with the steel member, wherein the steel member is a steel member.

7. A steel member according to any one of claims 1 to 6, The corrosion sensor is an electrical resistance type corrosion sensor, and is a steel member.

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