JP3987641B2 - Heavy duty anti-corrosion PC steel strand structure and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heavy-corrosion-protected PC steel stranded wire sealing structure and a sealing method. In more detail, cable-stayed cable for cable-stayed bridges, cable for precast bridge girders manufactured by short-line or long-line manufacturing processes, and PC cable installed outside of concrete, such as PC cable installed outside concrete, anti-corrosion for anchoring part of PC steel stranded wire The present invention relates to a sealing structure and a sealing method thereof.
[0002]
[Prior art]
In recent years, there are an increasing number of structures in which a number of PC steel strands are bundled to form a PC cable (PC tendon), which is placed outside the concrete and used as a tension cable.
[0003]
For example, there are cables for suspension bridges and cable-stayed bridges, and tight cables for precast bridge girders manufactured by a short line or long line manufacturing process. The heavy-duty-proof PC steel wire provided outside the concrete has the following advantages.
(A) The conventional inner cable embedded in concrete is designed to protect against corrosion by filling the sheath with grout material after the cable is tensioned. . A cable using a heavy-corrosion-proof PC steel wire uses a cable with a perfect anti-corrosion coating, so there is no such uncertainty.
(B) Management and maintenance are easy because the cable is visible.
(C) The cable can be replaced.
(D) A fixing unit, a deviator, and the like can be appropriately arranged.
(E) Suitable for corrosive atmosphere structures such as seaside structures.
[0004]
The Applicant has developed and provided a heavy duty PC steel strand most suitable for cables used outside such concrete. Such heavy anticorrosion PC steel strands are coated with polyethylene, epoxy, or the like. The heavy anti-corrosion PC steel strand is fixed to the fixing portion with a wedge or the like after peeling off the heavy anti-corrosion coating at the end. Therefore, the fixing portion is filled with a filler such as rust preventive oil for corrosion prevention. However, this rust preventive oil or the like leaks in the longitudinal direction of the tendon from the gaps between the wires of the many PC steels constituting the PC tendon, and the corrosion prevention of the fixing portion becomes incomplete.
[0005]
[Problems to be solved by the invention]
In order to maintain a perfect seal at the end fixing end of the tendon end of the heavy anticorrosion PC steel as described above,
(B) Technology to install a protective tube around the tendon and grout in it (b) Technology to seal the filling part using epoxy filler (c) Silicon rubber by tightening a bundle of wires from heavy anti-corrosion steel There has been a technique for sealing by removing the gap between the wires from the PC steel by deforming the coating such as urethane or urethane. These technologies were not perfect because the sealing effect was poor at a rate that was difficult to construct.
[0006]
It is an object of the present invention to provide a seal structure and a method for sealing a filler in a rust preventive material filling portion of an end fixing portion of a cable using a heavy anti-corrosion PC steel strand.
[0007]
[Means for Solving the Problems]
The present invention has been developed to solve the above-mentioned problems, and its technical means is to fill the gap between the PC strands of PC tendon with an elastic sealing material, and to fill the PC with a portion filled with the elastic sealing material. This is a heavy-corrosion-proof PC steel strand sealing structure in which a binding tape is wound around the outer periphery of the tendon and the longitudinal direction of the PC tendon is sealed. PC tendons formed by bundling a number of strands of PC steel have gaps between the strands of each PC steel. In the present invention, this gap is filled with an elastic sealing material to close the gap.
[0008]
Instead of the binding tape, a sealing structure in which an elastic sealing material is filled in a gap between the cylindrical outer tube and the outer periphery of the outer tube and the PC tendon may be used.
[0009]
The PC steel strand can be applied to any of a bare product, a synthetic resin coated product, an exterior coating product, or an unbonded type PC steel strand.
[0010]
The elastic sealant is an E.I. P. D. M.M. Foam, butyl rubber-based material, urethane / silicon-based material, or sponge having a main component can be used.
[0011]
As a method of forming the above-mentioned seal structure, a sheet of an elastic sealing material having an adhesive tape attached on one or both sides is wrapped around and adhered to a portion adjacent to each end fixing portion of a large number of PC steel strands, What is necessary is just to make the heavy-corrosion prevention PC steel wire sealing method characterized by bundling the winding portions of the sealing material of the many PC steel wires together and tightly winding a binding tape around the outer periphery thereof. Here, the portion close to the end fixing portion refers to a portion on the side opposite to the fixing end from the bare wire portion for fixing the stranded wire in the PC steel inside the fixing portion structure of the outer cable. It is a portion covered with a coated steel strand such as a heavy anti-corrosion PC steel strand, and a portion connected to a sheath with a bare wire. The winding length for winding and bonding the elastic sealing material sheet is preferably about 200 to 500 mm when the portion is a straight line, and about 500 to 1000 mm when the portion is a curve.
[0012]
Instead of the means for tightly winding the elastic sealing material sheet, the elastic sealing material sheet may be sandwiched between the PC steel wires.
[0013]
Further, instead of means for tightly winding the binding tape around the outer periphery, an elastic sealing material may be wound around the outer periphery of the bundle, and the synthetic resin tube may be tightly fitted around the outer periphery of the wound body of the elastic sealing material. . A polyethylene pipe or the like may be used as the outer pipe. In order to tightly fit, for example, the outer diameter of the elastic sealing material wound around the outer periphery of the PC tendon is made larger than the inner diameter of the polyethylene pipe, and the temperature of the outer pipe is increased to expand the outer diameter of the elastic sealing material. After being externally fitted to the diameter, it is possible to form a seal portion having a circular cross section of a complete seal by cooling and shrinking. The outer peripheral portion of this circular cross section is preferably in close contact with the inner surface of the end cap provided on the tendon exit side of the fixing body of the fixing portion.
[0014]
The operation of forming the above-described seal portion may be performed in a PC steel strand manufacturing plant, or may be performed at a PC tendon erection site. When it is carried out in a production plant for PC steel wire, it is easy to ensure completeness. However, if there is variation in the elongation after the wire tension of PC steel, the sealing positions at both ends may be slightly shifted. There is no fear that the position of the seal will be shifted if the seal is installed on site in the field, but it takes time to work on site.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The elastic sealing material used in the present invention will be described. The elastic sealant is a foam-type elastic material having open cells or closed cells. P. D. M.M. Is a foam, butyl rubber material, urethane / silicon material or sponge. E. P. D. M (ethylene / propylene / diene / methylene linkage) is an ethylene-propylene copolymer that can be sulfur vulcanized, and is excellent in weather resistance, cold resistance, heat resistance, and chemical resistance (acid, alkali). The compressive load is small and the structure is not deformed after filling. Compared to foamed materials such as urethane and polyethylene, it has a lasting resilience. Workability is excellent because it has adhesiveness. Butyl rubber sealants are characterized by excellent adhesion to rough surfaces. Urethane / silicone materials or sponges are also foams and have excellent elasticity and water permeation prevention. These elastic sealing materials are non-adhesive type sheet-like materials, and adhesive type roll-like materials in which a synthetic resin-based or butyl rubber-based adhesive is adhered to one or both sides and a separator is adhered thereon. be able to.
[0016]
Embodiments will be described below with reference to the drawings.
[0017]
FIG. 5 is a perspective view showing an example of a concrete bridge segment 50 using an external cable. A box girder in which a web 53 is provided between upper and lower floor slabs 51 and 52. A deviator 54 for inserting the outer cable is provided inside the box girder, and the outer cable does not pass through the concrete. FIG. 6 is a partial perspective view of a state in which a large number of segments 50 are connected to form a bridge body. In FIG. 6, the upper floor slab and one of the webs are notched to illustrate the arrangement of the outer cables in an easy-to-understand manner. The illustration of the inner cable is omitted. The outer cable 55 passes through the deviator 54 of each segment 50 and applies a bending force to each segment 50 to be tensioned. The outer cable 55 can be easily inspected and replaced.
[0018]
FIG. 4 is a longitudinal sectional view showing an example of an end fixing portion of a PC cable (PC tendon). A heavy anticorrosion coating is peeled off from the fixing end of each PC steel wire 23.
At the fixing end 12 of the concrete wall 11, there are an anchor plate 13 that supports the reaction force of the tension force of the PC cable, an anchor head 14 that passes through the end of the PC steel wire and is wedged, and a cover 15 that covers the fixing portion. Is provided. The cover 15 is provided with filling ports 16 which are filled with a sealing material.
[0019]
A fixing steel pipe 21 penetrating the concrete wall 11 is provided, and an output side cover 32 is provided on the output side end face 31 of the concrete wall 11. The fixing steel pipe 21 is connected to the anchor plate 13 and the outlet cover 32 to form a sealed space. Filler inlets 33 for filling the inside of the outlet cover 32 are also provided above and below. The heavy anticorrosion PC steel strand 25 penetrates through the fixing steel pipe 21, and the fixing end side coating is removed in the middle of the fixing steel pipe 21. In this state, the sealing material of the fixing portion leaks in the longitudinal direction of the tendon from the gaps between the multiple PC steel strands 25 constituting the PC tendon, and the corrosion prevention of the seal portion cannot be ensured.
[0020]
FIG. 3 is a partial longitudinal sectional view of the concrete wall 11 according to the embodiment of the present invention, and shows the outlet cover 32 side. A fixing unit (not shown) is provided on the left side of FIG. The seal portion 1 is formed inside the outlet cover 32 in the concrete wall 11 of the PC steel strand 25. A first embodiment of the AA sectional view of the seal portion 1 is shown in FIG. 1, and a sectional view of the second embodiment is shown in FIG.
[0021]
A heavy anticorrosion PC steel strand 25 is provided with a heavy anticorrosion coating 24. In FIG. 1, 19 PC steel strands 23 are bundled to form a PC cable (Tendon). An elastic sealing material 2 made of butyl rubber or urethane sponge is filled in the space between the stranded wires 23 of each PC steel, and a sealing material 3 such as putty is applied to the concave portion of the outer peripheral portion of the PC tendon. The tape 4 is tightly wound. The outer shape of the tape is the same as the opening shape of the outlet cover.
[0022]
In FIG. 2, instead of the tape winding of FIG. 1, an elastic sealing material or the like is wound around the outside of the tendon, and an outer tube such as a polyethylene pipe is tightly fitted around the outer periphery thereof. In this case, the opening of the outlet cover 32 shown in FIG. 3 may have a shape that matches the outer diameter of the outer tube.
[0023]
【The invention's effect】
As described above, according to the present invention, an elastic sealing material is filled in the gap between heavy anticorrosion PC steel strands, and a binding tape is wound around the outer periphery of the PC tendon in the portion filled with the elastic sealing material. Since the longitudinal direction of the PC tendon was sealed, it was possible to completely prevent leakage of the sealing material at the fixing portion of the heavy-corrosion-prevented PC steel wire, and complete retention of the anticorrosion structure was achieved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a seal portion of an embodiment.
FIG. 2 is a cross-sectional view of a seal portion according to an embodiment.
FIG. 3 is a longitudinal sectional view of a seal portion according to an embodiment.
FIG. 4 is a longitudinal sectional view of a fixing body.
FIG. 5 is a perspective view of a bridge segment showing an example.
FIG. 6 is a partially cutaway perspective view of the bridge body in the explanatory diagram of the outer cable.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sealing part 2 Elastic sealing material 3 Sealing material 4 Tape 5 Elastic sealing material 6 Outer pipe 11 Concrete wall 12 Fixing end part 13 Anchor plate 14 Anchor head 15 Cover 16 Filling port 21 Fixing steel pipe 23 PC steel strand 24 Coating 25 Heavy corrosion prevention PC steel strand 31 Outlet end face 32 Outlet cover 33 Filler inlet 50 Segment 51 Upper floor slab 52 Lower floor slab 53 Web 54 Deviator 55 Outer cable

Claims (7)

The gap between PC steel wires of PC tendon is filled with an elastic sealing material, and a binding tape is wound around the outer circumference of the PC tendon where the elastic sealing material is filled to seal the longitudinal direction of the PC tendon. Heavy duty anti-corrosion PC steel wire seal structure. The heavy-corrosion-proof PC steel strand sealing structure according to claim 1, wherein an elastic sealing material is filled in a gap between the cylindrical outer tube and the outer periphery of the PC tendon instead of the binding tape. The heavy-corrosion-proof PC steel strand sealing structure according to claim 1, wherein the PC steel strand is a bare product, a synthetic resin-coated product, an exterior coating product, or an unbonded type PC steel strand. . The elastic sealant is an E.I. P. D. M.M. The heavy-corrosion-proof PC steel strand sealing structure according to any one of claims 1 to 3, which is a foam, a butyl rubber-based material, a urethane / silicon-based material, or a sponge having a main component. A large number of PC steel strands are wound and bonded to a portion close to each end fixing portion of the strands of PC steel, and a sheet of elastic sealing material with an adhesive tape attached to one or both sides is wrapped and bonded. A heavy-corrosion-prevention PC steel wire sealing method characterized by bundling together winding portions of the steel and tightly winding a binding tape around the outer periphery thereof. 6. The heavy-corrosion-protected PC steel strand wire sealing method according to claim 5, wherein, instead of means for tightly winding the elastic sealant sheet, the elastic sealant sheet is sandwiched between the PC steel strands. . Instead of means for tightly winding a binding tape around the outer periphery, an elastic sealing material is wound around the outer periphery of the bundle, and a synthetic resin tube is tightly fitted around the outer periphery of the wound body of the elastic sealing material. The heavy-corrosion-protected PC steel strand sealing method according to claim 5 or 6.

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