JPH01263303A - Pc cable anchoring device - Google Patents

Abstract

PURPOSE:To enable the generation of a gripping force responding to a fluctuation stress exerted on a PC cable, by a method wherein the cable is anchored through combination of the conical trapezoidal tip of a sleeve and the inverted conical trapezoidal sleeve supporting hole of a pressure support plate. CONSTITUTION:The tip part 4 of a sleeve 3 made of a steel is formed in a conical trapezoidal shape, and division grooves 5 are circumferentially formed at equal intervals. An inverted conical trapezoidal sleeve support hole 7 having the same gradient as that of the conical trapezoidal tip part 4 of the sleeve 3 is formed in a pressure support plate 6 made of a steel. This constitution enables prevention of the occurrence of fretting corrosion of a PC cable due to an excessive shearing force, and also enables poor arrangement during execution of a work.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a PC cable fixing device,
Specifically, the present invention relates to a PC cable fixing device that is resistant to repeated stress and fluctuating stress, which prevents the occurrence of stress microcorrosion (so-called fretting corrosion) in the fixing portion of the PC cable.

[Prior Art] Conventionally, as fixing devices for PC cables, there are a so-called crimp grip as shown in FIG. 3, and a so-called wedge type grip as shown in FIG. 4.

As shown in Fig. 3, the so-called crimp grip has serrations on the inside that bite into the fixed end of the PC cable 1, and knurling on the outside that bites into the sleeve 11. grip the insert 2 and the PC cable 1 through this insert 2.
- a sleeve 11 which is crimped so as to Insert 2 and sleeve 11 to PC cable l
The crimping is carried out by inserting the insert 2 into the I) C cable l, covering it with the sleeve 11, and passing it through a die. This crimp grip contacts and supports the support plate 6 when the PC cable 1 it is gripping is pulled.

On the other hand, a so-called wedge type grip, as shown in FIG. 4, has a sleeve 13 provided with a truncated conical wedge receiving hole 12 and usually three pieces that correspond to the truncated conical wedge receiving hole 12 of the sleeve 13. It is composed of a wedge 14 in the shape of one truncated cone. The three pieces of wedge 14 form a cylindrical cavity 1 that grips the PC cable when assembled.
5. The wedge is inserted into the truncated conical wedge receiving hole 12.
As it is pulled in together with the C cable, it receives lateral pressure and clamps the PC cable.

[1-Problems to be Solved by the Invention] However, the conventional crimp grip as shown in FIG. 3 does not have a mechanism in which the holding force decreases even if the load applied to the C cable increases.

■Since the I) C cable is supported only by the gripping force due to plastic deformation, the holding force at the tip weakens due to the repeated application of fluctuating stress. As a result, the movement of the l)C cable at the tip end becomes difficult, and fretting: ]V'l-shot1 is more likely to occur. There were some drawbacks.

Furthermore, it is possible to manufacture a wedge type grip as shown in Fig. 4 that has predetermined fatigue characteristics by considering the angular relationship between the sleeve and the wedge, the shape of the teeth of the wedge, etc. However, when setting the PO cable to a constant J, there is a possibility that a step may be formed in the wedge, which may have an adverse effect on the fatigue characteristics. therefore,
On-site management at the time of establishment is 600% better. There were some drawbacks.

In recent years, in cable-stayed bridges where I) C cables are often used, the fatigue limit for repeated stress is usually 20 kg.
According to the applicant's fatigue tests, PC steel stranded wire (JIS G3536
The fatigue limit with respect to repeated stress was approximately 10 to 15 kg/mm 2 when a conventional pressure bonding grip was used to fix the 5Wl) R7Bφ15.2 mm). This is I)
This is considerably lower than the fatigue limit of the C steel stranded wire itself, and P
The CC cable wire breakage occurred near the end that abuts the bearing plate of the crimp grip. If the cause of fracture is due to low stress vibration 1,
Due to repeated stress, the holding force at the end of the crimp grip on the bearing plate side weakens, and due to repeated stress in this part, I]C
This is thought to be the cause because it causes fretting corrosion due to minute movement of the twisted wire.

[Means for Solving the Problems] The present invention solves the problems as mentioned above, and the gist thereof is as follows:] The present invention is a method of fitting and crimping the fixing end of a PC cable via an insert. a cylindrical sleeve, l
In the I) C cable fixing device, which is composed of a pressure plate that receives a sleeve that is pulled together with the C cable, the tip of the sleeve on the pressure plate side is shaped like a tapered truncated cone, and one or more grooves are formed from the tip. (On the other hand, there is provided a PC cable fixing device, characterized in that an inverted truncated conical sleeve receiving hole is provided for receiving the tapered truncated conical tip of the sleeve as the bearing pressure), and 2. The first aspect of the present invention is characterized in that a plurality of grooves are provided at equal intervals on the tip end of the bearing plate.
The PC cable fixing device described in Section 3.
The PC cable fixing device according to item 1 or 2, wherein the diameter of the cylindrical portion of the sleeve is larger than the maximum diameter of the tapered truncated conical tip portion.

In the present invention, it is more preferable that the length of the tapered truncated conical tip portion is longer than the length of the inverted truncated conical sleeve receiving hole in which the bearing pressure is temporarily provided.

Further, it is preferable that the slopes of the tapered truncated conical sleeve and the inverted truncated conical sleeve are approximately the same.

Although one or more grooves are provided, it is more preferable that they are polar symmetrical, have at least two grooves, and have a length of at least one-half of the length of the inverted truncated conical sleeve.

The insert is not particularly limited as long as it is commonly used in PC cable fixing devices. For example, a wire type or a 1' fall type may be used.

1) When a PC cable is fixed and dried using the fixing device of the present invention, 1) the C cable always bears a load. l:) When a load is applied to the C cable, the sleeve is pulled together with the PC cable and drawn into the inverted truncated conical sleeve receiving hole of the bearing plate. Since a groove is provided at the tapered truncated conical tip of the retracted sleeve, this serves as a deformation area, and a lateral pressure acts due to the imitation effect to strongly grip the PC cable.

As a result, compared to the crimp grip type, the I) C cable can be held better at the tip, and the movement of the I) C cable at the tip is reduced. Therefore, fretting corrosion is less likely to occur.

On the other hand, since the sleeve of the device of the present invention has a tapered truncated conical tip and a cylindrical portion integrally formed, a holding force is applied between the sleeve tip and the crimped portion, so that the sleeve has a tapered conical shape compared to the wedge type. The stress acting on the PC cable at the platform part is smaller than the wedge type.
A fatigue property of 1- can be expected. Since they are integrated at the crimp portion, they are not placed at different levels like wedge types.

Here, when the crimped portion is short, it has the effect of improving the arrangement of the different levels, but it is not preferable because II) the effect of sharing the holding force of the C cable becomes smaller.

Furthermore, when a breaking load is applied, the load is also held and shared by the cylindrical portion of the sleeve, making it possible to prevent an excessive increase in shearing force.

This makes it possible to prevent a decrease in breaking load.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the present invention, and FIG. 2 is a diagram showing a state in which the sleeve of the device according to the embodiment of the present invention is crimped onto the I) C cable. ) is a side view showing the same state, and FIG. 2(b) is a front view showing the same state.

Example 1 The tip 4 of a steel sleeve 3 was formed into a truncated cone shape as shown in FIGS. 1 and 2, and three grooves 5 were formed at equal intervals in the circumferential direction. On the other hand, the truncated conical tip portion 4 of the sleeve 3 is attached to the steel bearing plate 6. An inverted truncated conical sleeve receiving hole 7 with the same slope as +-1 is provided. The length of the truncated conical tip 4 of the sleeve 3 is longer than that of the sleeve receiving hole 7.

For Inner → Note 2, we used a cylindrical steel insert with striped serrations on the inside, knurling on the outside, and multiple grooves on both ends to allow for diameter reduction.

The PC1llil stranded wire 1 had a diameter of 5WPR713° and a diameter of 15.2 mm as specified in JIS G3536.

The fixed end of the PC steel stranded wire was covered with the insert 2, and the sleeve 3 was placed over the J-, and the wire was passed through a die and crimped.

This +1) C steel stranded wire] was tension-fixed to a bearing pressure temporary 6, and a fatigue test and a static tensile test were conducted.

The fatigue test results are shown in Figure 5. The test conditions were: The limited stress was 45% of the PCC steel stranded wire tensile strength, 11,970 kg, and the repeated stress range was changed to a frequency of 240 times/min (formerly 1
7. ). Furthermore, the results of the static tensile test are shown in FIG.

As is clear from the fatigue test results, the fixing device of the present invention was able to greatly improve the fatigue limit for fixing PC cables.Furthermore, the fatigue limit in the example of the present invention was 2(). kg/mm", and was sufficiently durable for practical use as a GJ0 cable fixing device for cable-stayed bridges.

[Effects of the Invention] As described in 1x below, according to the present invention, the combination of the truncated conical tip and the inverted truncated conical sleeve receiving hole provides a gripping force that corresponds to the fluctuating stress applied to the PC cable due to the wedge effect. It is an object of the present invention to provide a fixing device that can prevent the occurrence of fretting corrosion of PC cables due to excessive shearing force, can also prevent improper placement of PC cables, and can extend the life of PC cables. It is possible, and its practical effects are extremely impressive.

Furthermore, it provides a PC cable fixing device that is useful in fields that require high fatigue limits, such as cable-stayed bridges, and is an extremely effective invention that meets new needs.

Furthermore, since the PC cable can be crimped to the construction part in advance, the work at the site can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention. Fig. 2 is a diagram showing a state in which the sleeve of an embodiment of the present invention is crimped onto a PC cable, Fig. 2(a) is a side view showing the same state, and Fig. 2(b) shows the same state. It is a front view. FIG. 3 is a sectional view showing a conventional pressure grip type fixing device, and FIG. 4 is a perspective view showing a conventional wedge type fixing device. FIG. 5 is a diagram showing test results of a fatigue test of a conventional pressure grip and a fixing device according to an embodiment of the present invention, and FIG. 6 is a diagram showing test results of a static tensile test of a fixing device according to an embodiment of the present invention. 1...PC cable 2...Insert 3...Sleeve 4-...Tapered truncated conical tip 5...Split groove 6...Bearing plate 7...Inverted truncated conical sleeve receiving hole 11 ...Sleeve 12...Truncated conical wedge receiving hole J3...Sleeve 14...-Wedge 15...Cylindrical cavity

Claims (1)

[Scope of Claims] 1. In a PC cable fixing device consisting of a cylindrical sleeve that is fitted and crimped onto the fixing end of a PC cable via an insert, and a pressure plate that receives the sleeve that is pulled together with the PC cable, the pressure plate of the sleeve The side tip part has a tapered truncated conical shape, and one or more grooves are provided from the tip, while,
A PC characterized in that the bearing plate is provided with an inverted truncated conical sleeve receiving hole for receiving the tapered truncated conical tip of the sleeve.
Cable fixing device 2 PC cable fixing device 3 according to claim 1, characterized in that a plurality of grooves are provided at equal intervals on the tip end of the sleeve on the bearing plate side.The diameter of the cylindrical portion of the sleeve is tapered. The PC cable fixing device according to claim 1 or 2, wherein the PC cable fixing device is larger than the maximum diameter of the truncated conical tip.