PC steel bar structure

Abstract

To provide a PC steel bar structure that can suppress the leakage of rust inhibitors. [Solution] The PC steel bar structure comprises a PC steel bar having a first screw formed on the outer surface of at least a first portion, a resin sealing member covering the first portion, a sheath covering the portion of the PC steel bar not covered by the sealing member, and a resin sealing ring disposed between the first portion and the sealing member. The sealing member has a small-diameter portion having a second screw formed on its inner surface that screws into the first screw, and a large-diameter portion whose inner diameter is larger than the inner diameter of the small-diameter portion. The end of the sheath is disposed within the large-diameter portion. The sealing ring is disposed between the small-diameter portion and the sheath. The inner diameter of the sealing ring is larger than the diameter of the screw groove of the first screw and smaller than the diameter of the screw thread of the first screw.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to PC steel bar structures. [Background technology]

[0002] When constructing structures with concrete, prestressed concrete (PC) is sometimes used, which improves the strength of concrete by pre-applying compressive force to it, as PC concrete is weak in tensile forces. PC steel bars are used as members to apply compressive force to prestressed concrete. PC steel bars are rod-shaped members made of high-strength steel and are placed inside the concrete.

[0003] To suppress corrosion of PC steel bars, it is preferable that the PC steel bars do not come into direct contact with concrete. Therefore, the PC steel bars are enclosed in a resin sheath, a rust inhibitor is filled between the PC steel bars and the sheath, and concrete is placed outside the sheath. Furthermore, sealing members are placed at the ends of the sheath to prevent leakage of the rust inhibitor. In such PC steel bar structures, it is desirable to more effectively suppress the leakage of the rust inhibitor. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 7030071 [Overview of the project] [Problems that the invention aims to solve]

[0005] An objective of the embodiments of the present invention is to provide a PC steel bar structure capable of suppressing the leakage of rust inhibitors. [Means for solving the problem]

[0006] A PC steel bar structure according to an embodiment of the present invention comprises a PC steel bar having a first screw formed on the outer surface of at least a first portion, a resin sealing member covering the first portion, a sheath covering the portion of the PC steel bar not covered by the sealing member, and a resin sealing ring disposed between the first portion and the sealing member. The sealing member has a small-diameter portion having a second screw formed on its inner surface that screws onto the first screw, and a large-diameter portion whose inner diameter is larger than the inner diameter of the small-diameter portion. The end of the sheath is disposed within the large-diameter portion. The sealing ring is disposed between the small-diameter portion and the sheath. The inner diameter of the sealing ring is larger than the diameter of the screw groove of the first screw and smaller than the diameter of the screw thread of the first screw. [Effects of the Invention]

[0007] According to embodiments of the present invention, a PC steel bar structure capable of suppressing the leakage of rust inhibitor can be realized. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an exploded perspective view showing a PC steel bar structure according to an embodiment. [Figure 2] Figure 2 is an end view showing a PC steel bar structure according to an embodiment. [Figure 3] Figure 3 shows the relationship between the diameters of each part. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is an exploded perspective view showing a PC steel bar structure according to this embodiment. Figure 2 is an end view showing a PC steel bar structure according to this embodiment. Figure 3 shows the relationship between the diameters of each part.

[0010] As shown in FIGS. 1 and 2, in the PC steel bar structure 1 according to the present embodiment, a PC steel bar 10, a sealing member 20, a sheath 30, a sealing ring 40, a lubricating ring 50, and a rust inhibitor 60 are provided.

[0011] The PC steel bar 10 is a rod-shaped member made of steel and extending in the axial direction AX. The PC steel bar 10 is provided with a threaded portion 11 having a first thread 11a formed on the outer surface and a smooth portion 12 having no thread formed on the outer surface.

[0012] The sealing member 20 is a cylindrical member made of resin and covering a part of the threaded portion 11 of the PC steel bar 10. That is, the sealing member 20 surrounds a part of the axial direction AX (also referred to as the "longitudinal direction") of the PC steel bar 10. In the sealing member 20, a small-diameter portion 21 and a large-diameter portion 22 are integrally formed. A second thread 20a is formed on the inner surface of the small-diameter portion 21. The second thread 20a is screwed with the first thread 11a formed on the outer surface of the threaded portion 11 of the PC steel bar 10. The inner diameter of the large-diameter portion 22 is larger than the inner diameter of the small-diameter portion 21. No thread is formed on the inner surface of the large-diameter portion 22. A step 23 is formed between the small-diameter portion 21 and the large-diameter portion 22.

[0013] The sheath 30 is a sheet-like member made of resin and covers the portion of the PC steel bar 10 not covered by the sealing member 20. That is, the sheath 30 surrounds a part of the longitudinal direction of the PC steel bar 10. A third thread 30a is formed on the outer surface of the sheath 30. The pitch of the third thread 30a is larger than the pitch of the first thread 11a. The end portion 31 of the sheath 30 is disposed in the large-diameter portion 22 of the sealing member 20 and is disposed between the large-diameter portion 22 and the PC steel bar 10, thereby being fixed to the PC steel bar 10.

[0014] The sealing ring 40 is made of resin, for example, urethane rubber. The sealing ring 40 is disposed between the threaded portion 11 of the PC steel bar 10 and the large-diameter portion 22 of the sealing member 20. That is, the sealing ring 40 surrounds a part of the longitudinal direction of the threaded portion 11 of the PC steel bar 10.

[0015] The lubricating ring 50 is made of a material harder than that of the sealing ring 40, for example, an aramid fiber composite material. The lubricating ring 50 is, for example, "JOINT SHEET GASKET TOMBO NO. 1995". The lubricating ring 50 is disposed between the thread forming portion 11 of the PC steel bar 10 and the large diameter portion 22 of the sealing member 20, and between the step 23 of the sealing member 20 and the sealing ring 40. The lubricating ring 50 surrounds a part of the longitudinal direction of the thread forming portion 11 of the PC steel bar 10.

[0016] The rust preventive agent 60 is, for example, liquid or semi-solid, and is disposed between the PC steel bar 10 and the sheath 30.

[0017] Next, the diameters of each part are compared. As shown in FIG. 3, let the diameter of the thread groove of the first thread 11a formed in the thread forming portion 11 of the PC steel bar 10 be D in , in , , out , , out , out , out ,

[0019] , , in and the diameter of the thread crest be D out Also, let the inner diameter (diameter) of the sealing ring 40 be D1, the inner diameter (diameter) of the lubricating ring 50 be D2. Further, let the outer diameter (diameter) of the sealing ring 40 and the lubricating ring 50 be D4. Also, as shown in FIG. 1, let the inner diameter (diameter) of the large diameter portion 22 of the sealing member 20 be D5.

[0018] In this case, the inner diameter D1 of the sealing ring 40 is larger than the diameter D in of the thread groove of the first thread 11a and smaller than the diameter D out of the thread crest of the first thread 11a. Also, the inner diameter D2 of the lubricating ring 50 is larger than the inner diameter D1 of the sealing ring 40 and equal to the diameter D out of the thread crest of the first thread 11a. Note that "equal" includes not only the case of being completely identical but also the case of being "substantially equal" where the difference is within the tolerance range. That is, D in < D1 < D2 ≒ D out is satisfied.

[0019] In one example, the diameter D in [[ID=3​​6]]of the thread groove of the first thread 11a is 39 mm, and the diameter D [[ID=3​​7]] outThe diameter is 42 mm, the inner diameter D1 of the sealing ring 40 is 41 mm, and the inner diameter D2 of the lubrication ring 50 is 42 mm.

[0020] Next, a description will be given of how to use the PC steel bar structure 1 according to this embodiment. The PC steel bar 10 is covered with a sheath 30. A sealing ring 40 is fitted onto the threaded portion 11 of the PC steel bar 10. At this time, the inner diameter D1 of the sealing ring 40 is equal to the thread diameter D of the first thread 11a. out Because it is smaller than the PC steel bar 10, the sealing ring 40 is stretched and expanded before being fitted into the threaded portion 11. In this state, the sealing ring 40 tightens the PC steel bar 10 due to its elastic force, and thus the sealing ring 40 is fixed to the PC steel bar 10. However, the inner diameter D1 of the sealing ring 40 is equal to the diameter D of the thread groove of the first thread 11a. in Because it is larger, the sealing ring 40 does not reach the bottom of the thread groove of the first screw 11a.

[0021] Next, the lubrication ring 50 is fitted onto the threaded portion 11 of the PC steel bar 10. The inner diameter D2 of the lubrication ring 50 is the diameter D of the threads of the first thread 11a. out Because it is equivalent to this, the lubrication ring 50 is fitted into the threaded portion 11 of the PC steel bar 10 without substantially deforming, and there is no substantially gap formed between the threads of the first thread 11a of the threaded portion 11 and the lubrication ring 50.

[0022] Next, the PC steel bar 10 is inserted into the sealing member 20 together with the end 31 of the sheath 30, the sealing ring 40, and the lubrication ring 50, and the first thread 11a formed on the outer surface of the threaded portion 11 of the PC steel bar 10 is screwed into the second thread 20a formed on the inner surface of the small diameter portion 21 of the sealing member 20. As a result, the sealing ring 40 is sandwiched and compressed between the end 31 of the sheath 30 and the lubrication ring 50. This causes the sealing ring 40 to expand in the diametrical direction, improving the airtightness between the PC steel bar 10 and the sealing ring 40.

[0023] At this time, the sealing ring 40 rotates together with the PC steel bar 10, but because the frictional force between the sealing ring 40 and the lubrication ring 50, and the frictional force between the lubrication ring 50 and the step 23 of the sealing member 20 are low, the sealing member 20 does not rotate together with the PC steel bar 10. Next, the space between the PC steel bar 10 and the sheath 30 is filled with a rust inhibitor 60. Alternatively, a sheath tube (not shown) may be provided on the outside of the sheath 30 and fixed to the sheath 30 by screwing it with the third screw 30a.

[0024] Next, concrete is poured onto the outside of the PC steel bar structure 1. Then, a tensile force is applied to the PC steel bar structure 1. At this time, the sealing member 20 is fixed to the concrete, and the PC steel bar 10 moves axially AX relative to the sealing member 20, while the first screw 11a of the PC steel bar 10 breaks the second screw 20a of the sealing member 20. Next, the concrete is allowed to harden. After that, the tensile force applied to the PC steel bar structure 1 is released. As a result, a compressive force is applied to the concrete.

[0025] Next, the effects of this embodiment will be described. In this embodiment, the inner diameter D1 of the sealing ring 40 is equal to the thread diameter D of the first screw 11a. out Because it is smaller than the PC steel bar 10, a constant tension is applied to the sealing ring 40 when it is fitted onto the PC steel bar 10. This fixes the sealing ring 40 to the PC steel bar 10.

[0026] On the other hand, the inner diameter D1 of the sealing ring 40 is equal to the diameter D of the screw groove of the first screw 11a. in Because it is larger than the PC steel bar 10, there is no need to significantly deform the sealing ring 40 when fitting it onto the PC steel bar 10. For this reason, the sealing ring 40 can be made of a relatively hard and strong resin, such as urethane rubber. As a result, when the PC steel bar 10 is rotated relative to the sealing member 20, the sealing ring 40 is less likely to break. This effectively suppresses the leakage of the rust inhibitor 60.

[0027] Furthermore, the inner diameter D1 of the sealing ring 40 is equal to the diameter D of the thread groove of the first screw 11a. inBecause it is larger than the first screw 11a, the sealing ring 40 does not easily reach the bottom of the screw groove. Therefore, when the PC steel bar 10 is rotated relative to the sealing member 20, excessive load is prevented from being applied to the sealing ring 40. This also prevents the sealing ring 40 from breaking and effectively suppresses the leakage of the rust inhibitor 60.

[0028] Furthermore, by interposing a lubricating ring 50 between the step 23 of the sealing member 20 and the sealing ring 40, the sealing ring 40 is fixed to the sealing member 20 by the frictional force with the sealing member 20, thereby suppressing rotation relative to the PC steel bar 10. If the sealing ring 40 rotates relative to the PC steel bar 10, each part of the sealing ring 40 will sequentially move over the threads of the first screw 11a, making it prone to breakage.

[0029] The outer diameter (diameter) D4 of the sealing ring 40 and the lubrication ring 50 is not particularly limited as long as it can be fitted into the large-diameter portion 22 of the sealing member 20, but it is preferable that the outer diameter (diameter) D4 is less than or equal to the inner diameter (diameter) D5 of the large-diameter portion 22 of the sealing member 20.

[0030] The embodiments described above are examples that embody the present invention, and the present invention is not limited to these embodiments. For example, the present invention also includes the addition, deletion, or modification of some components in the embodiments described above.

[0031] The present invention includes the following embodiments.

[0032] (Note 1) A PC steel bar having a first thread formed on the outer surface of at least the first portion, A resin sealing member covering the first portion, A sheath that covers the portion of the PC steel bar not covered by the sealing member, A resin sealing ring is disposed between the first portion and the sealing member, Equipped with, The sealing member is A small-diameter portion having a second thread formed on its inner surface that engages with the first thread, A large-diameter portion whose inner diameter is larger than the inner diameter of the small-diameter portion, It has, The end of the sheath is positioned within the large-diameter portion. The sealing ring is positioned between the small-diameter portion and the sheath. The PC steel bar structure wherein the inner diameter of the sealing ring is larger than the diameter of the screw groove of the first screw and smaller than the diameter of the screw thread of the first screw.

[0033] (Note 2) The sealing ring is a PC steel bar structure made of urethane rubber as described in Appendix 1.

[0034] (Note 3) The PC steel bar structure according to Appendix 1 or 2, further comprising a lubricating ring disposed between the small-diameter portion and the sealing ring, the lubricating ring having an inner diameter larger than the inner diameter of the sealing ring and being harder than the sealing ring.

[0035] (Note 4) The PC steel bar structure described in Appendix 3, wherein the inner diameter of the lubrication ring is equal to the diameter of the threads of the first screw.

[0036] (Note 5) A PC steel bar structure according to any one of the appendices 1 to 4, further comprising a rust inhibitor disposed between the PC steel bar and the sheath. [Explanation of Symbols]

[0037] 1 PC steel bar structure 10 PC Steel Bar 11 Thread forming section 12 Smooth section 20 Sealing member 21 Small diameter part 22 Large diameter part 23 steps 30 sheaths 31 End 40 sealing rings 50 Lubrication Rings 60 Rust Inhibitor Inner diameter of D1 sealing ring 40 Inner diameter of D2 sliding ring 50 D in Diameter of the screw groove of the first screw D out Diameter of the first thread

Claims

1. A PC steel bar having a first thread formed on the outer surface of at least the first portion, A resin sealing member covering a portion of the first part, A resin sheath covering the portion of the PC steel bar not covered by the sealing member, A resin sealing ring is disposed between the first portion and the sealing member, Equipped with, The sealing member is A small-diameter portion having a second thread formed on its inner surface that engages with the first thread, A large-diameter portion whose inner diameter is larger than the inner diameter of the small-diameter portion, It has, The end of the sheath is positioned within the large-diameter portion. The sealing ring is positioned between the small-diameter portion and the sheath. The inner diameter of the sealing ring is larger than the diameter of the screw groove of the first screw and smaller than the diameter of the thread of the first screw, in this PC steel bar structure.

2. The PC steel bar structure according to claim 1, wherein the sealing ring is made of urethane rubber.

3. The PC steel bar structure according to claim 1, further comprising a lubricating ring disposed between the small-diameter portion and the sealing ring, the lubricating ring having an inner diameter larger than the inner diameter of the sealing ring and being harder than the sealing ring.

4. The PC steel bar structure according to claim 3, wherein the inner diameter of the lubrication ring is equal to the diameter of the threads of the first screw.

5. The PC steel bar structure according to claim 1, further comprising a rust inhibitor disposed between the PC steel bar and the sheath.

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