JPH0868158A - Fixing member and fixing part of PC stranded wire - Google Patents

Abstract

(57) [Abstract] [Purpose] When fixing PC steel strands in PC structures, prevent damage to the PC steel strands and improve fixing efficiency and fatigue strength. [Structure] The central axis E of the conical hole 66 of the anchor disk 6 for fixing the end of the PC steel strand 1 is located inside the central axis F of the guide hole 55 of the spacer 5 with respect to the central axis A of the sheath. It is characterized in that the PC stranded wire 1 is always held at the central position of the conical hole 66.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing portion of PC steel stranded wire in a PC (prestressed concrete) structure and a member used for fixing the same.

[0002]

2. Description of the Related Art In a PC structure, a PC steel strand inserted in concrete is tensioned and fixed by a fixing portion provided at its end.
The one shown in B is known.

In FIG. 3A, 1 is a PC stranded wire, 11
Is a PC steel material portion obtained by bundling a large number of PC steel strands and inserting them into the sheath 3 of the concrete 2. Reference numeral 33 denotes a trumpet sheath portion of the sheath 3, the outer end of which is in contact with the inner wall of the steel material insertion hole 44 of the anchor plate 4. Reference numeral 5 is a spacer inserted through the insertion hole 44, and reference numeral 55 is a guide hole for a large number of PC steel strands 1 provided near the outer periphery of the spacer 5. Reference numeral 6 is an anchor disk, and 66 is a large number of conical holes having the same central axis as the guide hole 55 provided in the disk 6. Reference numeral 7 is a wedge which is fitted into the conical hole and is held in contact with the strained PC steel wire 1.

FIG. 3B shows a bush 8 used in place of the spacer 5 shown in FIG. 3A.
The central axis of the guide hole 88 of FIG.
Like 55, it is the same as conical hole 66. In some cases, both the spacer 5 and the bush 8 may be used.

[0005]

2. Description of the Related Art As described above, in the conventional fixing portion structure in which the central axes of the guide holes 55 and 88 and the conical hole 66 are the same, the wedge 7 is inserted when it is temporarily placed before the tension. Although the PC steel strand 1 is located at the center of the conical hole 66,
When tensioned, it is biased toward the central axis side of the sheath 3 as shown in FIG. 4A. This is separated from the PC steel material 11 that was bundled in the center of the sheath 3 into each PC steel wire 1 to guide 55, 88.
It is because it is expanded and inserted into.

Due to this offset, when the wedge 7 is pushed in under tension in order to fix the PC steel stranded wire 1, the wedge piece 77 of the plurality of wedge pieces 77, which is on the offset side, has a conical hole 66. Since the gap with the wall is small, the wedge piece 77 of the portion 9 with a wide gap on the opposite side is in a floating state as soon as it comes into contact with the hole wall and the outer circumference of the stranded wire to reach the gripping state, as shown in FIG. 4A.

The diameter 10 of the smallest diameter portion of the conical hole 66 and the diameters of the guide holes 55 and 88 are both substantially larger than the diameter of the PC steel wire 1 and substantially the same. There is. In the wedge 7, a plurality of wedge pieces 77 are loosely integrated by a rubber ring or the like. Therefore, the PC
If you loosen the jack that is straining the steel stranded wire 1 and try to transfer the tension force to the wedge grip, the wedge pieces in the narrow gap are
Although 77 is slightly pulled in and fixed, the wedge piece 77 of the wide portion 9 is greatly pulled in and fixed, and the wedge 77 is fixed in an uneven state as shown in FIG. 4B.

Further, even if the wedge pieces 77 can be forcibly aligned so as to be aligned, the wedge piece 77 in the narrow portion is gripped with a strong force, and the gripping force of the wedge piece 77 in the wide portion 9 is weak. Therefore, in any case, the side pressure on the PC steel strand 1 becomes imbalanced at the wedge fixing portion, and the fixing is unstable. This leads to deterioration of fixing efficiency and fatigue characteristics and causes damage to the PC steel strand.

[0009]

The present invention has been made by focusing on the above-mentioned problems and clarifying the cause of the unevenness of the wedge pieces 77. That is, as described above, since the central axis of the conical hole of the conventional anchor disk and the central axis of the guide hole of the spacer are provided on the same axis line and the hole diameters are also substantially the same, the bundled PCs drawn into the sheath. Stranded steel wire,
If they are spread apart at the trumpet sheath portion and pulled into the conical holes through the guide holes, respectively, and tensioned, the center of each bundle of PC steel strands, that is, from the axis corresponding to the sheath center axis to the guide hole and the conical hole. Since the wire is pulled while sliding on the wall of the hole on the axis line side, the wire does not come into contact with the PC steel wire on the inner wall on the opposite side of the hole, and a wide gap portion 9 is formed.

As a result, inconsistencies occur. Therefore, in the present invention, as shown in FIGS. 1A and 2, the guide hole hole wall B on the equivalent axis A side is replaced with the same hole hole wall of the small diameter portion 10 of the conical hole. The outer periphery of the PC steel stranded wire 1 which is displaced from C to the outside with respect to the corresponding axis line and pulled in and tensioned is the guide hole hole wall B.
The first feature is that even if the slides, it does not come into contact with the conical hole wall C.

In order to configure this feature, a method in which the central axes of both holes are on the same axis and the hole diameter of the guide hole is small,
There is a method in which the hole diameters are the same and the central axes are displaced. It is preferable that the hole diameter is small within a range that does not hinder the insertion of the PC steel wire from the viewpoint of wedge prevention and economically. Therefore, the method of shifting the central axis will be described in detail. The central axis of the sheath is referred to as the sheath center-corresponding axis because the bundle of PC steel wires on the concrete center side of the trumpet portion may use a ring instead of the sheath.

Another feature of the present invention is that the center axis of the conical hole is inserted to the outside of the guide hole hole wall B in the radial direction from the corresponding axis line so that the center axis is shifted. That is, it is selected to be provided at a position of 1/2 length of the diameter D. With this configuration, the PC steel strand is corrected in the axial direction by the guide hole, is strained in the conical hole without being biased, and is fixed by the wedge.

[0013]

【Example】

Used PC steel material Group A Diameter 15.2mm (5.1mm x 7) PC steel stranded wire
A bundle of 19 pieces. Group B A bundle of 19 pieces of 15.2 mm diameter (5.1 mm x 7 pieces) PC steel stranded wire coated with epoxy resin. Used anchor disk group C Steel disk with a diameter of 240 mm and a thickness of 80 mm,
Conical hole 19 perpendicular to the disk surface with a small diameter 10 of 17 mm
A book is provided. However, the central axis of the conical hole is on the same axis as the central axis of the guide hole below. Group D Same as above However, the central axis of the conical hole is located at the outer side in the radial direction from the equivalent axis by 1/2 length of the diameter D of the PC steel wire from the hole wall B closest to the sheath center axis equivalent axis of the guide hole. To position. Spacer group E used A spacer made of hard polyethylene with a diameter of 170 mm and a thickness of 60 mm, with 19 guide holes perpendicular to the surface of the spacer with a diameter of 17 mm. Bushing group F used 19 bushes with a diameter of 40 mm and a thickness of 20 mm, and a guide hole perpendicular to the bushing surface with a diameter of 17 mm.

Using the above-mentioned members, the constituent positions shown in FIGS. 1A and 1B are used in the embodiment, and the constituent positions shown in FIGS. 3 and 4 are used in the comparative example. Different combinations of the members are as follows. A fixing unit composed of was created.

Example 1 Group A + D + E configuration Group B + D + E configuration Example 2 Group A + D + F configuration Group B + D + F configuration Example 3 Group A + D + E + F configuration Group B + D + E + F configuration Comparative example 1 Group A + C configuration Group B + C configuration Comparative example 2 Composition of group A + C + E Composition of group B + C + E Comparative example 3 Composition of group A + C + F Composition of group B + C + F

An actual load was applied to each of the fixing portions having the above-described configurations to make them tense, and after the tense, they were unloaded, and the fixing efficiency, damage degree, and fatigue characteristics were measured. The results are shown in Table 1, Table 2 and Table 3.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

The numbers in Table 2 indicate the number of PC steel strands that have been damaged. When observing after removing the wedge after tension and removing the wedge, If even one strand was damaged, it was judged that the PC stranded wire (PC steel material 11) was damaged.

The conditions in Table 3 are that the upper limit load is 45% of the standard tensile load (227.43tf) and the stress amplitude is 25 kgf / mm ² (6
It is 5.88tf), and 2 million is the harshest possible number of iterations. The number of tests was 4 cables for each configuration.

[0022]

As is clear from the test results in the above-mentioned Examples and Comparative Examples, the fixing section constituted by using the fixing member according to the present invention has a higher strength than the conventional fixing section in the PC steel strand during tension fixing. Is much less damaged. Moreover, the fixing efficiency is good and the fatigue strength is high.

As described above, this effect is obtained by the PC.
Conical hole 66 of anchor disk 6 through which steel strand 1 is inserted
Since the central axis E of the guide hole 55 is inside the central axis F of the guide hole 55 of the spacer 5 with respect to the sheath central axis equivalent axis A, the hole wall B on the side close to the sheath central axis equivalent axis A of the guide hole 55 is slid. The outer circumference of the PC steel wire 1 that is moved and drawn does not hit the similar hole wall C of the conical hole 66, and is always the conical hole 66.
Is kept in the central position of. When the central axes E and F are provided on the same axis, the diameter 10 of the small diameter portion of the conical hole 66 is increased, for example, from the difference between the diameter of the wire 1 and the guide hole diameter of PC steel or about 1/2 thereof. By doing so, the same effect can be obtained. Therefore, this method may be adopted, but in terms of operation and cost, the diameter 10 of the small diameter portion of the conical hole 66 is
It is more preferable not to make the diameter the same as the guide hole and increase the diameter.

In FIG. 2B, in the hole wall of the guide hole 55 of the spacer 5, a portion farther from the sheath center axis equivalent line A, that is, a portion which does not slide on the hole wall even when the PC steel wire 1 is pulled in and tensioned is missing. The part 12 is provided. Similarly, when the missing portion 12 is provided in the guide groove 88 of the bush 8, there is no change in the function as a fixing member, and sometimes it is advantageous in terms of operation and cost. It doesn't matter.

As described above, since it is kept in the center position, when the wedge 7 is pushed in while the PC steel wire 1 is tensioned with a jack or the like, each wedge piece 77 is pushed into the uniform search and the jack is loosened. When the tension force is transferred to gripping the wedge piece 77, there is no deviation in the depth of the wedge piece 77 dragged by the PC steel strand 1, and the search is very slight.
Therefore, the damage to the PC steel wire 1 by the wedge 7 is small, the fixing efficiency is improved, and the fatigue strength is good.

[Brief description of drawings]

FIG. 1A and FIG. 1B are side cross-sectional views of a part of a fixing unit for explaining the structure of the fixing unit in the first and second embodiments, respectively.

FIG. 2A is a conical hole of the anchor disk of FIG. 1A,
FIG. 5 is an explanatory view from the front showing the relative position of the central axis of the guide hole of the spacer, and B is a front view showing the case where a missing portion is provided in the wall of the guide shaft hole of the spacer.

3A and 3B are side cross-sectional views showing the configurations of fixing units of Comparative Example 2 and Comparative Example 3, respectively.

4A and 4B are side sectional views of a part of a fixing unit for explaining a wedge state in Comparative Example 2 shown in FIG. 3, respectively.

[Explanation of symbols]

1 PC steel stranded wire 11 PC steel stranded wire bundle (PC steel material)
2 Concrete 3 Sheath 33 Trumpet sheath 4 Anchor plate 44 Anchor plate insertion hole 5 Spacer 55
Spacer guide hole 6 Anchor disk 66 Conical hole of anchor disk 7 Wedge 77 Wedge piece 8 Bush 88 Bush guide hole 9 Widely spaced part 10 Diameter of the smallest diameter part of the conical hole A Center axis of the sheath (same center) Equivalent axis) B 55 hole hole closest to A hole wall C 10 hole diameter closest to A diameter D 1 center axis E 66 center axis F 55, 88 center axis 12 missing guide hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeo Akasaki 1-1-1 Kunyo Kita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works

Claims (5)

[Claims] 1. An anchor disk having a plurality of conical holes for wedges, which is used for fixing PC strands, and a spacer and / or a bush having a plurality of guide holes, wherein the central axis of the conical holes is a sheath. It is characterized in that the central axis thereof is located radially inward of the central axis of the guide hole corresponding to the conical hole with respect to the axis corresponding to the central axis of the sheath, except for the one coincident with the central axis equivalent axis line. Fixing member for PC steel strands. 2. An anchor disk having a plurality of conical holes for wedges used for fixing PC strands and a spacer and / or a bush having a plurality of guide holes, wherein the conical holes and the central axes of the guide holes are A fixing member for a PC steel strand, which is on the same line and in which the diameter of the small diameter portion of the conical hole is larger than the diameter of the guide hole. 3. The anchor disk, the spacer and / or the bush are orthogonal to the axis corresponding to the central axis of the sheath, the wedge conical hole and the central axis of the guide hole provided in the anchor disk are parallel to the equivalent axis, and the conical cone for the wedge is formed. The distance at which the central axis of the hole is located radially inward of the central axis of the guide hole is such that the central axis of the wedge conical hole is inserted through the guide wall from the hole wall closest to the axis corresponding to the central axis of the sheath of the guide hole. The fixing member according to claim 1, wherein the distance is a distance generated by providing a half of the diameter of the PC steel wire to the outside in the radial direction from the corresponding axis. 4. The fixing member according to claim 1, wherein the guide hole of the spacer and / or the bush has a missing portion on the hole wall on the side far from the axis corresponding to the sheath center axis. 5. The anchoring of the end of the strained PC stranded wire,
A fixing part for a PC steel strand, comprising the member according to claim 1, 2, 3 or 4.