JPS605718B2 - Anti-corrosion coated cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corrosion-resistant coated cable used as a cable for constructing a suspended structure such as a cable-stayed cable for a cable-stayed bridge.

As this type of anti-corrosion coated cable, cables in which the cable body is covered with a pipe and grout material is injected into the gap between the two have been known for a long time.Cement milk or cement mortar is used as the grout material because it is inexpensive. is commonly used.

Such an anti-corrosion coated cable is expected to have a double anti-corrosion effect in that even if water leaks into the pipe due to pipe breakage, the grout protects the cable body from corrosion. However, conventionally, in the above-mentioned anti-corrosion coated cable, the grout material such as cement milk is strong in compression but weak in tension, and when the cable body is stretched under load, it easily cracks, and if the crack is large, water can leak out from there. This has the disadvantage that the corrosion prevention effect is significantly inhibited.

In other words, conventionally, for example, in cable-stayed cables for cable-stayed bridges, grout is injected into the gap between the pipe and the cable body while the cable body covered with the pipe is being erected. (load) is acting on the cable, but after the bridge is completed, live loads such as vehicle loads are added to this and the cable body stretches, which is related to the fact that grout materials such as cement milk are weak in tension as mentioned above. Cracks appear in the hardened grout,
Water enters from here and the cable body becomes susceptible to corrosion.
This shortens the useful life of the cable. In addition, to prevent the occurrence of cracks, polymer cement, rubber, resin, etc. may be used as grout materials as materials that stretch well under tension, but these materials are If it is relatively expensive and too soft, there will be problems such as the filled grout material flowing down due to gravity and forcing the pipe to expand.

In view of these circumstances, the present invention has been developed to prevent the occurrence of cracks after completion of a suspended structure even when using a grout material that is inexpensive and hardens sufficiently, but has low tensile strength, thereby increasing the anticorrosion effect and significantly extending the service life. It is an object of the present invention to provide a corrosion-resistant coated cable that can be extended in length. Hereinafter, the present invention will be explained with reference to illustrative embodiments.

FIG. 1 shows a schematic structure of a cable-stayed bridge as an example of a suspended structure. In the figure, A is a cable-stayed cable, B is a bridge deck, and C is a bridge tower. Corrosion-proof coated cables are used.

FIG. 2 shows the cross-sectional structure of this anti-corrosion coated cable A, which consists of a cable body 1 and a pipe 2 having an inner dimension larger than the outer diameter of the body 1 and covering the body 1.
and a time-hardening grout material 3 filled between the main body 1 and the pipe 2 and prestressed. The cable body 1 is usually a parallel wire cable made of a large number of wires bundled in parallel, and the pipe 2 is made of metal such as stainless steel, aluminum, iron, or plastic. Further, as the grout material 3, cement milk, cement mortar, etc., which are inexpensive and harden sufficiently, are used. Then, at the time of grout injection, in addition to the dead load due to the cable-stayed bridge's own weight, a load equivalent to the live load is applied to the cable body 1 as shown by the arrow in Fig. 2, and the grout is 2 is poured, and after the grout material 2 hardens, the load corresponding to the live load is removed, thereby imparting compressive force, that is, prestress, to the grout material 2. As a means of applying a load equivalent to the dead load in addition to the dead load in order to apply prestress in this way, for example, when the cable body 1 is covered with the pipe 2 and installed in a predetermined state, As shown by the line, a heavy object D corresponding to the live load may be placed on the bridge deck B,
Alternatively, as shown in Fig. 3, the tension of the loaded vehicle may be applied by tensioning the cable body using anchors E installed below the bridge.

Regarding the application of such prestress, to give an example with concrete numerical values, the stress due to dead load acting on cables in cable-stayed bridges etc. is usually within the range of 20 to 60k9/min, and if this stress is reduced to 40k9/min, If the cable stress fluctuation due to live load is 115k9/secret ~ 5k9/fence, then 55X9/iso stress corresponding to [stress due to dead load + maximum value of stress due to live load] is added to the cable body. In this state, inject the grouting material.

Then, by removing the live load after the grout hardens, the maximum stress due to the live load, that is, the stress of 15k9/ground. A compressive strain corresponding to s is given, and this strain z is calculated as follows, assuming that the elastic modulus of the cable body is Es=20000k9/pine! OS/ES=15/20000=〇. 〇.

〇75. Therefore, the elastic modulus of the grout material is Es: 2
000k9/fence, the compressive stress generated in the grout material is ric'Ecz = 2000 x 0.00075 = 1
．． 5 (k9/fence) or this compressive stress.

c is approximately 150k9/corresponding. This is an acceptable value if the strength of the grout material is controlled to a certain level. By applying prestress to the grout material 3 in this way, even if a live load acts on the cable after the completion of a cable-stayed bridge, etc.,
In the grout material 3, the live load is absorbed by the prestress, no tensile stress is generated, and therefore no cracks occur.

As described above, the anti-corrosion coated cable of the present invention applies prestress to the grout material by a load equivalent to the live load in addition to the dead load of the suspended structure, so the live load is applied to the cable after the suspended structure is completed. Even if the grout acts on the cable, no tensile stress is generated in the grout material, which prevents cracks from occurring.Even if the covered pipe is damaged, the grout material prevents water from entering the cable body. The dual anti-corrosion effect of preventing corrosion of the cable can be well maintained, and the useful life of the cable can be significantly extended.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of a cable-stayed bridge as an example of a suspended structure, Fig. 2 is a partial sectional view of the anti-corrosion coated cable according to the present invention, and Fig. 3 is a schematic side view of a cable-stayed bridge as an example of a suspended structure. It is a schematic side view of the cable-stayed bridge which shows another example. A...Cable, 1...Cable body, 2
...Pipe, 3... Grout material. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 A cable for constructing a suspended structure, which is made by covering the cable body with a pipe having an inner diameter larger than the outer diameter of the cable body, and injecting and filling the gap between the two with a time-hardening grout material. A corrosion-resistant coated cable characterized in that the grout material is prestressed by a load equivalent to the live load in addition to the dead load of the suspended structure.