JPH04118406A - Vibration proof cable for cable-stayed bridge - Google Patents

Abstract

PURPOSE:To prevent damage by making the peripheral surface of a covering material such as synthetic resin, etc., to cover a stranded cable binding stranded conductors as a regular polygon in excess of a specific polygon. CONSTITUTION:A stranded cable 10 binding a large number of stranded conductors is coated with a covering material 11 of synthetic resin such as polyethylene, etc. The peripheral surface of the covering material 11 is a regular polygon in excess of a heptagon, every solid angle is an obtuse angle, and one crest line 12a of the crest lines 12 of the peripheral surface is so placed that it is put upward of a perpendicular line. According to the constitution, damages in the case of winding, transportation and construction can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vibration-isolating cable for cable-stayed bridges, and is primarily directed to rain vibration.

(Prior Art) Problems caused by wind on cable-stayed bridge cables include vortex excitation vibration, wake galloping, and rain vibration. Countermeasures against these include cable interconnections, dampers, and aerodynamic countermeasures depending on the target.

Conventional aerodynamic countermeasures primarily aimed at preventing rain vibrations in cable-stayed bridge cables include the following:

In Fig. 10, the outer periphery of a strand 1 made of bundled wires is covered with a synthetic resin covering material 2, and a spiral protrusion 3 is provided on the outer periphery of this covering material 2 (Japanese Patent Publication No. 62-60512). Public bulletin).

In FIG. 11, a large number of parallel protrusions 4 are provided on the outer periphery of a covering material 2 (Japanese Patent Application Laid-Open No. 197703/1983).

In FIG. 12, a large number of stripes 5 are provided on the outer periphery of the covering material 2 (Japanese Unexamined Patent Publication No. 1-146006).

(Problem to be Solved by the Invention) This type of anti-vibration cable is manufactured in advance at a factory and then transported to the site and installed. has the following issues:

That is, the vibration-proof cable shown in FIG. 10 is difficult to manufacture because the cable or extruder must be rotated during manufacture.

Furthermore, there is a risk that the protrusion 3 may be damaged or the base of the protrusion 3 may be torn during reel winding or transportation of the vibration-proof cable after manufacture, or during installation. Furthermore, there is a risk that the base of the protrusion 3 may be torn due to deterioration due to ultraviolet rays due to aging after construction.

The anti-vibration cable shown in FIG. 11 has the same problems as the former in terms of deterioration over time as well as during winding, transportation and erection. Moreover, rainwater flows between the parallel protrusions 4 and causes the rainwater to accumulate in the vicinity of the girder measurement point of the cable, which is undesirable from the viewpoint of corrosion protection of the girder and the cable base.

In the anti-vibration cable shown in FIG. 12, the bottom of the stripe 5 may be torn during reeling or transportation.

Further, there is a problem similar to the first two during construction, and there is a risk that the bottom of the stripe 5 may be torn due to ultraviolet deterioration after construction. In addition, rainwater flows down the bottom of stripe 5, and
The situation will be similar to the case shown in the figure.

In view of such conventional problems, the present invention provides a vibration-proof cable for cable-stayed bridges that is easy to manufacture, can prevent damage during winding, transportation, and erection, and can eliminate the problems of damage caused by aging and rainwater. It is something to be offered.

(Means for Solving the Problems) The present invention provides a cable for cable-stayed bridges in which the outer periphery of a strand 10 made of bundled wires is covered with a sheathing material 11 made of synthetic resin, etc. It is a regular polygon.

The outer periphery of the covering material 11 is a regular heptagon, a regular octagon, a regular 9-gon, or a regular 10-gon.

One of the ridgelines 12 on the outer periphery of the covering material 11 is arranged vertically upward.

(Function) Since the outer periphery of the sheathing material 11 is a regular polygon of more than a regular heptagon, all its corners are obtuse angles, making it easy to manufacture and preventing damage during reeling, transportation, and erection. It can also prevent damage caused by aging. Furthermore, it drains well when it rains. Therefore, rainwater does not flow down the cable to the base thereof, which is favorable for preventing corrosion of the girder and the base of the cable.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows a first embodiment of the present invention. Numeral 10 is a strand formed by bundling a large number of wires, and is covered with a covering material 11 made of synthetic resin such as polyethylene. Covering material 11
The outer circumference is a regular octagon, and one of its ridges 12
2a is arranged vertically upward.

The anti-vibration cable 13 having the above structure was obliquely strung in a three-dimensional direction as shown in Fig. 2, and the vibration damping effect was investigated through a wind tunnel experiment. A certain place was confirmed.

The results of this experiment are shown in FIG. In Figure 3, the solid line a is α=45°, β=O'', and the solid line b is α=45°, β=20°.
C is α=45°, β=40', d is α=45°β=
45". The dotted line shows the results of a wind tunnel experiment in which water traveling through the cable was artificially added to a normal cylindrical cable. However, α=β=45°.

If the outer circumference of the sheathing material 11 is made into a regular octagonal shape in this way, it is easy to manufacture, and at the same time, all corners are obtuse angles, so that it is easy to manufacture the outer circumference of the sheathing material 11. This is very advantageous in all respects, since damage to the protrusion itself, the base of the protrusion, the bottom of the stripe, etc., may occur.

Furthermore, since the outer circumference is a regular octagon and one of the ridgelines 12a is vertically upward, water drains well during rain, and rainwater that has traveled along the cable does not flow to the cable base.

Therefore, there is an advantageous effect in terms of corrosion protection of the girder and cable base.

The vibration-proof cable 13 may have one ridgeline 12a vertically upward, or may have one plane 12b vertically upward. Also in this case, as shown in FIG. 4, a sufficient vibration damping effect was obtained compared to the cylindrical cable.

The outer periphery of the covering material 11 is not limited to a regular octagon, but may be a regular polygon such as a regular heptagon shown in FIG. 5, a regular 9-gon shown in FIG. 6, or a regular 10-gon shown in FIG. That's fine.

Incidentally, when a cable was manufactured in which the outer peripheral shape of the sheathing material 11 was a regular hexagon to a decagon, and its damping effect was measured in a wind tunnel experiment, the results shown in FIG. 9 were obtained. Judging from FIG. 9, it is desirable that the outer periphery of the covering material 11 be a regular polygon of a regular heptagon or more. In addition, in FIG. 9, the measurement results at each angle number indicate the maximum amplitude.

The covering material 11 only needs to have a regular polygonal cross section, and may be spirally twisted over the entire surface as shown in FIG.

(Effects of the Invention) According to the present invention, since the outer periphery of the covering material 11 is made into a regular polygon of heptagon or more, it is easy to manufacture, and it also prevents damage during reel winding, transportation, and erection, or over time. It can prevent damage caused by changes, and also solve problems caused by rainwater during rainy days.

Furthermore, if one of the ridgelines 12 is placed vertically upward, drainage of rainwater is further improved.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a cable showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the same wind tunnel experiment, Figs. 3 and 4 are diagrams showing the relationship between wind speed and amplitude, and Figs. FIG. 8 is a perspective view of a cable showing another embodiment, FIG. 9 is a view showing the maximum amplitude of each model, and FIGS. 10 to 12 are perspective views showing a conventional example. 10- Strand, 11- Covering material, 12- Ridge line.

Claims (3)

[Claims] (1) In a cable-stayed bridge cable in which the outer periphery of a strand (10) made of bundled wires is covered with a covering material (11) such as a synthetic resin, the outer periphery of the covering material (11) is a regular polygon of heptagon or more. Anti-vibration cable for cable-stayed bridges. (2) Claim 1 characterized in that the outer periphery of the covering material (11) is a regular heptagon, a regular octagon, a regular 9-gon, or a regular decagon.
Anti-vibration cable for cable-stayed bridges described in . (3) The anti-vibration cable for a cable-stayed bridge according to claim 1 or 2, characterized in that one of the ridgelines (12) on the outer periphery of the covering material (11) is arranged vertically upward.