JP2004131956A - Grout cap of pc wire anchorage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grout cap capable of surely preventing PC wire from being corroded by increasing liquid tightness in a PC wire anchorage used to provide a pre-stress to a PC member. <P>SOLUTION: In this grout cap 20, by using transparent or semi-transparent resin material, a fixing flange part 20e is formed at the peripheral edge of an opening 21 for receiving the PC wire anchorage C therein, and the projected end part 20b thereof is formed in hemispherical shape, and the entire part thereof is generally integrated in a hat shape. A large number of projected parts 20c are formed on the outer peripheral surface thereof parallel with each other at intervals around the axis thereof. Either of these projected parts 20c is selected so that screw hole for connecting a grout filling port to an exhaust port can be postprocessed in the projected part 20c. Then, the grout cap 20 is put on the PC wire anchorage C to hold a PC wire B in a tensioned state to cover the anchorage liquid-tight so as to protect the PC wire. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for prestressing a PC member (prestressed concrete member) by grasping both ends of a PC steel wire inserted into a sheath pipe provided in the PC member. The present invention can be applied to a fixing device for a PC steel wire that fixes a steel wire in a predetermined tension state. More specifically, the present invention relates to a grout cap that covers such a PC steel wire fixing device to protect the PC steel wire.
[0002]
2. Description of the Related Art Generally, relatively long PC members used for construction of roads, railways, bridges, etc. are pre-compressed with a PC steel wire at the time of construction in order to supplement the tensile strength of concrete. We give construction to give.
[0003]
Conventionally, when prestressing is applied to a PC member using a PC steel wire, as shown in FIGS. 6 and 7, for example, a plurality of PC steel wires 3 are provided in a sheath tube 2 provided inside the PC member 1. ..., and the other end of the PC steel wire 3 fixed at one end is pulled and tightened by using a jack or the like. When a predetermined tension is applied, the PC steel wire 3 is fixed to a predetermined tension state by using the fixing tool 4. After that, the inside of the sheath tube 2 is grouted to fix the PC steel wire 3 to the PC member 1, and a compressive prestress is applied to the PC member. An embedding concrete 5 is poured into the mounting recess 1 a formed at the end of the PC member 1, and the fixing tool 4 is covered with the concrete 5 to seal the end of the PC steel wire 3.
[0004]
Conventionally, this type of fixing tool 4 is provided between a female cone 6 having a truncated conical through hole 6a through which the PC steel wire 3 is inserted, and an inner peripheral wall of the through hole 6a which is fitted to the female cone 6. And a male cone 7 for holding the PC steel wire 3 therebetween. The male cone 7 is provided with a holding groove 7a having a semicircular cross section for positioning and holding the PC steel wire 3 along the length direction of the outer peripheral wall thereof, and a plurality of grooves are formed at predetermined intervals around the axis. ing.
[0005]
When fixing the PC steel wire 3 in a predetermined tension state, the other end of the PC steel wire 3 fixed at one end is pulled by a jack or the like and tensioned, so that the male cone 7 is pushed into the female cone 6. The PC steel wire 3 is fixed, and as a result, the PC steel wire 3 is fixed in a tension state, so that the PC member 1 is prestressed.
[0006]
The PC steel wire 3 to be fixed by the above-described conventional fixing device 4 is formed by weaving a plurality of strands 3a, as shown in FIG. 8, for example. Therefore, even though the PC steel wire 3 is sandwiched between the inner peripheral wall of the female cone 6 and the holding groove 7a of the male cone 7, there is a gap between the strands 3a, so that the PC steel wire 3 passes through the slight gap. Water penetrates in the length direction and stays in the middle of the length direction, and the accumulated water corrodes each of the wires 3a, thereby causing a problem that the strength of the PC steel wire 3 is reduced and the PC steel wire 3 is broken. Sometimes. In particular, when the intruding water contains a salt, the corrosion progresses remarkably, and there is a high risk of occurrence of such a problem.
[0007]
Further, even when the fixing device 4 is covered with the embedded concrete 5 to seal the end of the PC steel wire 3 as in the conventional case, the embedded concrete 5 deteriorates with time and cracks occur. However, there is a problem that rainwater or the like easily penetrates through the cracks and still lacks liquid tightness.
[0008]
Therefore, an object of the present invention is to provide a grout cap that enhances liquid tightness and reliably prevents corrosion of a PC steel wire in a PC steel wire fixing device used when prestressing a PC member. is there.
[0009]
Therefore, in order to achieve the above object, the invention described in claim 1 is provided in a PC member A, for example, as shown in the embodiment described below with reference to the drawings. The both ends of the PC steel wire B inserted into the sheath tube 10 are gripped, and the PC steel wire B is covered with a PC steel wire fixing device C for holding the PC steel wire B in a tensioned state, and the fixing device C is liquid-tight. A grout cap 20 to cover, using a transparent or translucent resin material, a fixing flange 20e is provided on the periphery of the opening 21 for receiving the fixing tool C, and the protruding end 20b side is formed in a hemispherical shape. A plurality of convex portions 20c are arranged on the outer peripheral surface at intervals around the axis, and one of the convex portions 20c is selected and formed on the outer peripheral surface. 20c is provided with a screw hole 20d for connecting the grout inlet and exhaust port. And characterized by being factory can configured.
[0010]
Embodiments of the present invention will be described below with reference to the drawings.
[0011]
FIG. 1 is a partial longitudinal sectional view of a PC member in a state where a tensioned PC steel wire is fixed by a PC steel wire fixing tool. FIG. 2 is a front view of the PC steel wire fixing device. In the figure, reference symbol A denotes a PC member, reference symbol B denotes a PC steel wire, and reference symbol C denotes a PC steel wire fixing tool.
[0012]
The PC member A is a prestressed concrete product such as a beam already formed into a long material having a predetermined shape, and a sheath tube 10 made of a spiral tube is previously installed in a center hole formed in the length direction. I have. Reference numeral 11 denotes a grit streak to which the fixing device C is fixed. At the end of the concrete 12 of the PC member A, a mounting recess 12a is formed, and the fixing tool C is assembled in the mounting recess 12a.
[0013]
In the illustrated example, a plurality of PC steel wires B are inserted through the sheath tube 10 and are formed by weaving a plurality of strands. The sheath tube 10 is formed of a material that seals the PC steel wire B inserted into the hollow duct and the concrete 12 in a liquid-tight manner and has corrosion resistance to moisture, salt, and the like, for example, a non-ferrous metal.
[0014]
The PC steel wire fixing tool C has a guide connection 13 in which an inner end 13a is connected to an end edge of the sheath tube 10 and is fixed by a grit streak 11, and a supporting plate fixed to an outer end 13b of the guide connection 13 having an enlarged diameter. 14 is provided. The support plate 14 has a frame plate shape, and has a circular hole 14a having a large tapered inner peripheral surface at the center. Then, it is provided on the fixing step 12b provided at the bottom of the mounting recess 12a, and is bolted to the guide connection 13. The female cone 15 is fitted into the circular hole 14a of the support plate 14, and the male cone 16 is fitted into the truncated conical through hole 15a of the female cone 15.
[0015]
The female cone 15 has an annular flange portion 15b on the outer periphery of the end on the enlarged diameter side, the annular flange portion 15b engaging with the edge of the circular hole 14a when fitted to the supporting plate 14. The male cone 16 has a grout hole 16a at the center, and the outer peripheral surface is formed by a taper surface having substantially the same inclination angle as the inner peripheral surface of the through hole 15a of the female cone 15. Further, the male cone 16 is provided with semi-circular holding grooves 16b for positioning and holding the PC steel wire B along the length direction of the outer peripheral surface, and the holding grooves 16b are spaced from each other around the axis. , And a plurality of PC steel wires B are formed in accordance with the number of insertions. The PC steel wire B is sandwiched between the holding groove 16b and the inner peripheral wall of the through hole 15a of the female cone 15.
[0016]
Now, in the present invention, the above-described PC steel wire fixing tool C is particularly provided with a grout cap 20 which covers the cover and liquid-tightly.
[0017]
The grout cap 20 according to the present invention is integrally formed using a transparent or translucent resin material, for example, a nylon resin. As shown in FIGS. 3 and 4, the side of the body 20a having the opening 21 into which the fixing device C is inserted is formed in a substantially truncated cone shape, and the side of the protruding end 20b is integrally connected in a hemispherical shape. It is formed into a hat shape as a whole.
[0018]
Further, on the outer peripheral surface of the grout cap 20, near the protruding end portion 20b of the body portion 20a, convex portions 20c having a flat surface are arranged in a line at intervals around an axis passing through the center of the opening 21. ing. Thereby, any one of the convex portions 20c is arbitrarily selected, and as shown by a dotted line in the figure, the screw hole 20d for connecting the grout inlet and the exhaust port can be post-processed. An annular fixing flange 20e is provided on the periphery of the opening 21, and a plurality of bolt holes 22 are provided in the flange 20e at intervals. Further, a large number of reinforcing ribs 20f are provided on the fixing flange 20e and are arranged radially. Note that an O-ring 23 is attached as a sealing material to the periphery of the fixing flange 20e near the opening 21.
[0019]
Now, the case where the prestressed PC member A is applied to fix the tensioned PC steel wire B using the PC steel wire fixing tool C will be described below with reference to FIGS. 1 to 4.
[0020]
In this case, in the present invention, before use, the grout cap 20 is provided with a convex portion 20c suitable as a position where the screw hole 20d is formed for connecting the grout inlet and the exhaust port, if necessary, in advance. select. Then, screw holes 20d are respectively formed in the arbitrarily selected convex portions 20c, and a grout injection pipe 25 made of, for example, a nipple and an exhaust pipe 26 are screwed into the screw holes 20d and connected in advance.
[0021]
At the construction site, the PC steel wire B is inserted through the hollow duct of the sheath tube 10, the female cone 15 is fitted into the circular hole 14a of the support plate 14, and the end of the plurality of PC steel wires B is inserted into the through hole 15a. Then, the male cone 16 is fitted into the through hole 15a of the female cone 15, and the PC steel wire B is fitted into each holding groove 16b to temporarily fix the end.
[0022]
Next, using a jack (not shown), the other end of the PC steel wire B fixed at one end is pulled and tensioned, and under a predetermined tension, the male cone 16 is pushed into the female cone 15 and the PC steel wire is pressed. Fix line B. After fixing to a predetermined tension state by the fixing tool C, the jack is removed.
[0023]
Thereafter, the grout cap 20 is put on the fixing tool C, and the fixing flange 20 e is fixed to the support plate 14 with the bolt 29 with the O-ring 23 interposed therebetween. Thereafter, grout is injected through the grout injection pipe 25 to fill the entire length of the sheath pipe 10.
[0024]
At the time of grout injection, the operator can visually check the grout injection state from outside through the grout cap 20 and confirm that the grout is injected without lack.
[0025]
Further, in the grout cap 20, especially since the protruding end portion 20 b is a hemispherical hat type, even if a high grout injection pressure [for example, 1.96 MPa (20 atm)] is generated in the grout cap 20, the inner wall of the cap may be formed. The pressure is not concentrated on a part of the surface, but is evenly distributed along the spherical surface. Therefore, it is possible to prevent deformation due to a high grout injection pressure.
[0026]
After the grout is injected, an embedded concrete 30 is separately poured into the mounting concave portion 12a of the PC member A, and the fixing tool C is covered and protected by the concrete 30. On the other hand, when the grout hardens in the sheath tube 10, the compressive force of the PC steel wire B is transmitted to the PC member A via the hardened grout and the sheath tube 10, and as a result, the PC member A has sufficient compression force against tensile stress. Prestress will be applied.
[0027]
In the PC member A thus obtained, the end of the PC steel wire B is cut off by the grout cap 20 to be isolated from the embedded concrete 30. Therefore, even if the embedded concrete 30 is cracked and rainwater or the like penetrates from the crack, , Does not reach the end of the PC steel wire B because it is blocked by the grout cap 20. As a result, corrosion and rust of the PC steel wire B are prevented, and problems such as a decrease in strength and breakage of the PC steel wire B can be prevented.
[0028]
By the way, in the illustrated embodiment described above, the O-ring 23 is attached to the grout cap 20 as a sealing material at the opening edge of the fixing flange 20e. However, in the present invention, as shown in FIG. 5, it is also possible to provide a structure in which the annular convex portion 20 g is integrally provided in the circumferential direction of the fixing flange portion 20 e by resin molding to improve the sealing property. As a result, the number of parts can be reduced and the cost can be reduced because no separate sealing material is used.
[0029]
In the illustrated embodiment described above, an example is shown in which the grout cap 20 of the present invention is applied to a construction method in which a plurality of PC steel wires B that are inserted through the sheath tube 10 and are tightened are held by the fixing tool C. However, the present invention does not exclude the same application to a construction method in which a PC steel wire B inserted and tensioned and held by a fixing tool C is similarly applied. is there.
[0030]
According to the present invention configured as described above, the following effects can be obtained.
[0031]
According to the present invention, the grout cap is formed of a resin material, and the resin grout cap is covered with the PC steel wire fixing tool to cover the PC steel wire in a liquid-tight manner. -Prevents the penetration of salt and the like, prevents corrosion and rust of the PC steel wire caused by such moisture and salt, etc., and as a result, reliably prevents problems such as reduced strength and breakage of the PC steel wire. be able to.
[0032]
Furthermore, since the grout cap according to the present invention is formed to be transparent or translucent so that the grout injection state can be visually recognized from the outside, when grout is injected, the operator can visually check the grout injection state from outside through the grip cap. Then, it can be confirmed that grout is injected without lack.
[0033]
In addition, the grout cap according to the present invention has a configuration in which the protruding end side is formed in a hemispherical shape and is integrally formed into a hat shape as a whole. Therefore, even if a high grout injection pressure is generated inside, the cap inner wall is formed. Since pressure is not concentrated on a part and is evenly distributed along the spherical surface, it can be prevented from being deformed by high grout injection pressure. As a result, prestress is properly applied to PC members. Can be provided.
[0034]
Moreover, according to the grout cap of the present invention, on the outer peripheral surface, a number of convex portions are arranged at intervals around the axis, and one of the convex portions is selected to connect the grout inlet and the exhaust port. In order to pre-stress the PC member, select a suitable convex part as a position for opening the grout inlet and exhaust port, and drill the screw hole as necessary in the prestressing work of the PC member. The grout injection pipe and the exhaust pipe can be screwed into these screw holes and connected in advance.
[Brief description of the drawings]
FIG. 1 is a partial sectional view showing an assembled state of a PC steel wire fixing device having a grout cap according to an embodiment of the present invention to a PC member.
FIG. 2 is a front view of a PC steel wire fixing device.
FIG. 3 is a longitudinal sectional view of a grout cap.
FIG. 4 is a side view of a grout cap.
FIG. 5 is a partial sectional view showing another sealing structure of the grout cap according to the present invention.
FIG. 6 is a partial sectional view showing an assembled state of a conventional PC steel wire fixing device to a PC member.
FIG. 7 is a front view of a conventional PC steel wire fixing device.
FIG. 8 is a partially enlarged front view of a conventional PC steel wire fixing device.
[Explanation of symbols]
A PC member B PC steel wire C PC steel wire anchor 10 Sheath tube 20 Grout cap 20b Head 20c Convex portion 20d Screw hole 20e Fixing flange 21 Opening

Claims (1)

The both ends of the PC steel wire inserted into the sheath pipe provided inside the PC member are gripped, and the PC steel wire is covered with a PC steel wire fixing device that holds the PC steel wire in a tensioned state, and the fixing device is liquid-tight. A grout cap to cover,
Using a transparent or translucent resin material, a fixing flange portion is provided on the periphery of the opening for inserting the fixing device, and the protruding end side is formed in a hemispherical shape and integrally molded into a hat shape as a whole,
On the outer peripheral surface, a number of convex portions are arranged at intervals around the axis, and one of the convex portions is selected, and a screw hole for connecting the grout inlet and the exhaust port is formed in the convex portion. A grout cap for a PC steel wire fixing tool, wherein the grout cap is configured to be machined.

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