JP2001207388A - Heavy corrosion resistant PC steel strand and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a defect that a coat is bent in the deflected part of a PC(precast concrete) tendon used as an external cable and the coat is damaged in the inlet-outlet part of a hole when the PC tendon is tensed or undergoes load fluctuation and/or temperature change, which leads to the danger that the PC tendon made of heavy anticorrosion twisted PC steel wires suffers an injury. SOLUTION: The outer periphery of each twisted PC steel wire 10 in the deflected part of the PC tendon external cable made of the heavy anticorrosion twisted PC steel wires is provided with an outer coat 5 to result in duplex coating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty PC steel strand. More specifically, the present invention relates to a heavy-corrosion-proof PC steel stranded anticorrosion seal structure of a deflection part of a PC tendon used as an external cable for binding a precast bridge girder or an external cable of a concrete structure, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, many PC steel strands have been bundled to form a PC.
Increasingly, cables (PC tendons) are formed, arranged outside concrete as outer cables of structures, and used as tension cables. For example, there is a cable for a cable-stayed bridge or a cable for binding a precast bridge girder manufactured by a short line or long line manufacturing process. Conventionally, a heavy-duty anticorrosive PC steel strand is used as an outer cable. The heavy-corrosion-resistant PC steel stranded wire is a wire in which the outer periphery of the galvanized PC steel wire is coated with polyethylene or the outer periphery of the epoxy-coated PC steel wire is coated with polyethylene. Such anticorrosive PC steel strands provided outside concrete have the following advantages. (A) A conventional cable buried in concrete is provided with a grout material in a sheath after the cable is tensioned to protect it from corrosion. However, it is hard to say that the grout material is completely and completely filled. In the case of a PC tendon using a heavy-corrosion-proof PC steel strand as an outer cable, a cable having a perfect anticorrosion coating is used, so there is no such uncertainty. (B) Since the installed PC tendons are in a visible state, management and maintenance are easy. (C) PC tendons can be replaced. (D) The fixing unit, the deviator (a component of the deflection unit of the PC tendon) and the like can be appropriately arranged. (E) Suitable for structures in corrosive atmosphere such as seaside structures.

The present applicant has developed and provided a heavy-duty PC steel stranded wire which is most suitable as an external cable used outside such concrete.

[0004]

In the deflection part of the PC rod, which is a heavy-corrosion-proof PC steel strand, a half tube or sheet of polyethylene is fitted on the outer circumference of the PC rod to cure the PC rod. In the deflection part of this PC tendon, PC
The coating is bent as the tendons deflect the direction.
For this reason, when tension is applied to the PC tendon, or when the PC tendon expands or contracts due to a load change or a temperature change, a flaw may occur in the coating at the entrance and exit of the deflecting portion, and the PC tendon may be damaged. is there.

[0005] That is, when the PC tendon is inserted into the hole of the deviator and set on the deflection portion, or when the PC tendon is tensioned by applying tension, the strand may be displaced and the strand may be damaged. In order to prevent this, it is necessary to lengthen or enlarge the length of the polyethylene half pipe inserted into the deflection section, or to monitor by a person to prevent abnormalities during the retracting or tensioning work of the PC tendon. There is.

[0006] In view of such circumstances, the present invention provides a heavy duty anticorrosion P
Heavy corrosion-resistant PC with a structure that prevents damage to PC tendons due to bending of PC tendon deflection parts using C steel strands
An object of the present invention is to provide a steel strand and a method for manufacturing the same.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been developed to solve the above-mentioned problems, and its technical means is to apply a polyethylene coating to the outer periphery of a galvanized PC steel strand or an epoxy-coated PC steel strand. A heavy-corrosion-resistant PC steel stranded wire, characterized in that a double coating is provided on the outer circumference of each PC-strand wire of the deflection part of the PC tendon outer cable formed of the heavy-corrosion-proof PC steel stranded wire. It is a stranded wire.

[0008] In this case, it is preferable to interpose a lubricant in the intermediate layer of the double coating, since slippage occurs here and the coating is not forced. Further, the thickness of the outer coating of the double coating may be 0.5 to 3.0 mm. 0.5mm
If it is thinner, it may be damaged during production, transportation, erection work and the like. When the thickness is more than 3.0 mm, it is difficult to pass through the holes of the fixing unit and the deflecting unit during the installation. The optimal thickness is between 1.0 and 2.0 mm.

Preferably, a polyethylene pipe coating is further provided on the outer circumference of the double coating, and one or more selected from the group consisting of a lubricant, an elastic sealing material, and an epoxy resin are provided between the double coating and the outer polyethylene pipe. The protection is more effective when multiple inclusions are involved.

[0010] The method of the present invention is a method for producing a heavy-corrosion-protected PC steel strand, which comprises producing the heavy-corrosion-resistant PC steel strand in a factory and transporting it to an installation place. It is easy to achieve perfection by manufacturing PC steel strands in a manufacturing plant.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, the related art will be described. FIG. 11 is a perspective view showing an example of a concrete bridge segment 50 using an outer cable. The bridge segment 50 is a box girder provided with a web 53 between the upper and lower floor slabs 51 and 52. A deviator 54 through which an outer cable is inserted is provided inside the box girder.
It is arranged to be exposed to the space through the hole of the concrete and does not pass through the inside of the concrete wall. FIG. 12 is a partial perspective view showing a state in which a number of such bridge body segments 50 are connected to form a bridge body. In FIG. 12, the arrangement of the outer cable 55 is shown for easy understanding by notching the upper floor slab 51 and one of the webs 53. The illustration of the inner cable is omitted.
The outer cable 55 is connected to the deviator 5 of each bridge segment 50.
4, it is tensioned and imparts a bending force to each bridge segment 50. The outer cable 55 can be easily maintained and inspected, and can be replaced.

FIG. 7 is a sectional view of a conventional heavy-corrosion-proof PC steel strand 30. Each of the PC steel strands 1 is provided with a zinc plating or an epoxy coating 2, and a strand of the PC steel strand 1 is provided with a polyethylene coating 3 on the outer periphery thereof. Some spaces between the PC steel strands 1 are filled with grease 4. FIG. 8 is a cross-sectional view of a PC tendon 31 formed by bundling nineteen anticorrosion steel strands 30. When this PC tendon 31 is used as an external cable, it is pulled into the hole 32 of the deviator as shown in FIG. When the PC tendon 31 is strained, the deflection portion of the deviator deforms as shown in the cross section in FIG. For this reason, there has been a problem that the cable is damaged due to a load change or a temperature change, and the effect of heavy corrosion protection is reduced. In order to prevent this, conventionally, as shown in FIG. 10, a half tube 33 made of polyethylene is inserted into the hole 32 of the deviator to prevent the PC tendon 31 from being damaged and to maintain the heavy corrosion protection effect. But it was not enough.

FIG. 1 shows a heavy duty anticorrosion PC steel strand 1 according to the present invention.
FIG. 7 is a cross-sectional view illustrating an example of the present invention. In FIG. 1, the point that each of the strands of the PC steel strand 1 is provided with zinc plating or epoxy coating 2 and the outer circumference of the strand composed of the PC steel strand 1 is coated with the polyethylene coating 3 is shown in FIG. It is the same as the conventional heavy duty anticorrosion PC steel strand 30. In the embodiment, an outer coating 5 is provided as a double coating on the outer periphery of each PC stranded wire in a portion corresponding to the deflection portion of the PC tendon outer cable formed of the heavy corrosion-resistant PC stranded wire.
It is preferable that the material of the outer coating 5 is also made of polyethylene. FIG. 2 is a cross-sectional view of another embodiment, in which a lubricant 6 is interposed between a conventional polyethylene coating 3 and an outer coating 5.

FIG. 3 shows an example of the anticorrosion steel stranded wire 10 of the embodiment.
FIG. 2 shows a cross section of the PC tendon 20 that has been put together, in a state where the PC tendon 20 is inserted into a hole 32 of a deviator. FIG.
FIG. 4 shows a cross section of the PC tendon 20 of the deflection unit when the tension is tightened. Heavy corrosion-resistant PC steel strand 10 shown in FIG.
Is double-coated, the outer coating 5 and the lubricant interposed therein effectively protect the heavy-corrosion-resistant steel strand 10, and when the PC tendon 20 of the deflecting portion passes through the deflecting portion. Even if the PC tendon 20 is bent at the entrance / exit of the hole of the deflecting portion, the double coating material of the many PC steel strands 10 constituting the PC tendon 20 prevents damage due to bending, and does not cause flaws.

FIG. 5 shows a heavy duty anti-corrosion PC provided with the double coating.
A cross-sectional view of an example in which a polyethylene pipe covering 7 is further provided on the outer periphery of a PC tendon 20 made of a steel strand 10, and FIG. 6 shows a longitudinal cross-sectional view thereof. This double-coated heavy-corrosion-resistant PC steel strand 10 and its surrounding polyethylene pipe coating 2
When an intervening material 8 selected from the group consisting of a lubricant, an elastic sealing material, and an epoxy resin is interposed between the outer cable 1 and the outer cable 1, damage to the deflection portion of the outer cable can be completely prevented. The protection of the outer cable used in is completely achieved.

[0016]

As described above, according to the present invention,
The heavy duty anticorrosion PC steel wire of the deflection part has a double coating structure, so when tension is applied, even when there is a load change or temperature change, only the internal PC steel wire moves, and the flaw is only the outer coating. Absorption was able to completely prevent the occurrence of flaws in the deflection portion of the heavy-corrosion-resistant PC steel strand, and complete maintenance of the heavy-corrosion-proof structure was achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a heavy-duty PC steel stranded wire according to an embodiment.

FIG. 2 is a cross-sectional view of another embodiment of a heavy-corrosion-resistant PC steel strand.

FIG. 3 is a normal cross-sectional view of a PC tendon made of a heavy-corrosion-proof PC steel strand of an embodiment.

FIG. 4 is a cross-sectional view of the PC tendon of the embodiment when tensioned.

FIG. 5 is a cross-sectional view of the PC tendon of the embodiment.

FIG. 6 is a longitudinal sectional view of a PC tendon of the embodiment.

FIG. 7 is a cross-sectional view of a conventional heavy-corrosion-resistant PC steel strand.

FIG. 8 is a normal cross-sectional view of a conventional PC tendon.

FIG. 9 is a cross-sectional view of a conventional PC tendon when tensioned.

FIG. 10 is a cross-sectional view of a conventional PC tendon.

FIG. 11 is a perspective view of a bridge body segment.

FIG. 12 is a partially cutaway perspective view of a bridge body, illustrating an external cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PC steel strand 2 Zinc plating or epoxy coating 3 Polyethylene coating 4 Grease 5 Outer coating 6 Lubricant 7 Polyethylene coating pipe 8 Inclusion 10 Heavy corrosion prevention PC steel strand of an example 20 PC tendon of an example 30 Conventional heavy corrosion protection PC steel strand 31 Conventional PC tendon 32 hole 33 half pipe 50 bridge segment 51 upper floor slab 52 lower floor slab 53 web 54 deviator 55 outer cable

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D059 BB39 GG02 GG23 2E164 AA02 AA11 AA31 BA06 DA01 3B153 AA45 BB15 CC13 CC26 CC52 CC74 DD21 FF02 FF03 GG07

Claims (6)

[Claims] 1. A cable outside a PC tendon formed by a heavy corrosion-resistant PC steel stranded wire in a heavy corrosion-resistant PC steel stranded wire having a polyethylene coating on the outer periphery of a galvanized PC steel stranded wire or an epoxy-coated PC steel stranded wire. A heavy-duty anticorrosive PC steel stranded wire, characterized in that a double coating is provided on the outer periphery of each of the PC steel stranded wires. 2. The heavy duty anticorrosion PC steel strand according to claim 1, wherein a lubricant is interposed in the intermediate layer of the double coating. 3. The thickness of the outer coating of the double coating is 0.5.
The heavy-corrosion-protected PC steel strand according to claim 1 or 2, wherein the diameter is from 3.0 to 3.0 mm. 4. The heavy duty anticorrosion PC steel wire according to claim 1, wherein a polyethylene pipe coating is further provided on the outer periphery of the double coating. 5. The method according to claim 1, wherein one or more inclusions selected from the group consisting of a lubricant, an elastic sealing material, and an epoxy resin are interposed between the double coating and the polyethylene pipe coating on the outer periphery thereof. The heavy corrosion-resistant PC steel stranded wire according to claim 4. 6. The heavy duty anticorrosion P according to any one of claims 1 to 5.
A method for producing a heavy-duty anticorrosion PC steel strand, wherein a steel strand is manufactured, transported and attached at a factory.