JPH0819154A - Extension and compression absorbing method of power cable laid on bridge - Google Patents

Abstract

PURPOSE:To provide an extension and compression absorbing method of power cable laid on bridge which enables absorption of extension and compression without taking offset of power cable on the bridge. CONSTITUTION:An extension and compression absorbing method of power cable laid on a bridge can absrob expansion and compression of cable due to expansion and compression of bridge beams and that due to temperature change of power cable by fixing the upper fixing plate 5 of the R section to the end part of the bridge beam 1, placing the lower fixing plate 6 of the R section on the ground at the lower side of the plate 5, bending the power cable laid on the bridge at the right angle with the radius R at the upper fixing plate 5 of the R section and then fixing the power cable therein, and moreover bending the power cable at the right angle with the radius R at the lower fixing plate 6 of the R section and fixing the cable therein, and giving looseness 8 to the power cable 4 at the dropping section between the upper and tower fixing plates 5, 6 of the R section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for expanding and contracting a bridge laying power cable which falls at the bridge end.

[0002]

2. Description of the Related Art In addition to the thermal expansion and contraction of the power cable itself due to temperature changes and energization, the power cable laid on the bridge is expanded and contracted at the joints and ends of the bridge girder. Conventionally, as a means for absorbing the expansion and contraction, a slack portion (offset portion) is formed in the power cable on the bridge girder, and it is absorbed by a change in the bending radius of the offset portion.

FIG. 2 is a diagrammatic explanatory view of an example of the conventional expansion / contraction absorbing method described above. The bridge girder 1 expands and contracts on the support 3 such as Teflon provided on the pier 2 due to temperature change, load change, and the like. The power cable 4 laid on the bridge transmits the expansion and contraction of the bridge girder 1 to the left end of the offset part 10 by the rod 9 attached to the ground side so that the expansion and contraction can be absorbed by the offset part 10, as shown in FIG. , The bending radius of the offset portion 10 changes 10 'to absorb. m'indicates the amount of expansion and contraction.
The power cable 4 on the left side of the offset portion 10 does not have to absorb the expansion and contraction of the bridge girder 1, so it is fixed to the wall surface with the cleat 7 at regular intervals and descends to the ground.

[0004]

In the above-described conventional expansion and contraction absorbing method, the size of the offset cannot reduce the bending radius in the example of the ultra high voltage power cable, and the distortion of the metal sheath caused by the bending radius change is caused. Normally, width is 5m and total length is 15m because it must be kept within the allowable value.
A very large space is required, and there is often no space for offset installation.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a method for expanding and contracting a bridge laying power cable which enables expansion and contraction without offset on the bridge. Is to fix the R-section upper fixing plate to the bridge girder end, and install the R-section lower fixing plate on the ground below it, and connect the power cable laid on the bridge at a right angle to the radius R with the R-section upper fixing plate. Bend and fix the bridge girder by bending it at a right angle to the radius R with the lower fixing plate of the R part, and at the same time, extend and contract the bridge girder by slackening the power cable in the falling part between the R part upper and lower fixing plates. It is to absorb the expansion and contraction due to the temperature change of the power cable.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagrammatic explanatory view of a specific example of the expansion and contraction absorbing method of the present invention. In the drawing, the same reference numerals as those in FIG. 2 represent the same parts. As shown in the drawing, an R-section upper fixing plate 5 is fixed to the end of the bridge girder 1, and an R-section lower fixing plate 6 is installed below it on the ground. The power cable 4 laid on the bridge is fixed by the cleat 7 at the end of the bridge girder 1 without any offset on the bridge girder 1. The power cable 4 is bent at a right angle to the radius R by the R-part upper fixing plate 5 and is erected downward. Then, the power cable 4 is fixed to the R-section upper fixing plate 5 by the cleat 7. The power cable 4 lowered downward is an R-section lower fixing plate 6, which is bent at a right angle to a radius R and laid horizontally. Then, the power cable 4 is fixed to the R-section lower fixing plate 6 with the cleat 7. At this time, the R upper fixing plate 5 and the R
A slack 8 is provided on the power cable 4 at the falling portion between the lower part fixing plates 6.

[0007]

In the above-mentioned structure, when the bridge girder 1 extends by the length m, the R-section upper fixing plate 5 moves by the length m to the left side in the figure as shown by the dotted line in the figure. Along with this, the slack 8 of the power cable at the falling portion also changes 8'as shown by the dotted line in the figure to absorb the extension of the bridge girder 1. The slack 8 of the power cable in the falling portion can also absorb expansion and contraction of the power cable itself due to temperature changes.

[0008]

As described above, according to the expansion / contraction absorbing method of the present invention, the power cable offset portion is provided on the bridge from the bridge girder end to the ground without forming the power cable offset portion on the bridge. Since it absorbs expansion and contraction due to slack,
It can be applied to bridges with a small space. Further, since the natural bending deformation of the slack formed at the falling portion of the power cable is utilized, the structure is simple and economical. Therefore, it is extremely effective when used for the expansion and contraction absorption method of ultra high voltage power cables for bridge construction.

[Brief description of drawings]

FIG. 1 is a diagrammatic explanatory view of a specific example of a stretching and absorbing method of the present invention.

FIG. 2 is a diagrammatic explanatory view of an example of a conventional expansion / contraction absorbing method.

FIG. 3 is an explanatory diagram of an absorption state of extension of a bridge girder in the offset portion of FIG.

[Explanation of symbols]

 1 Bridge girder 2 Bridge pier 3 Bearing 4 Power cable 5 R part upper fixing plate 6 R part lower fixing plate 7 Cleat 8 Slack

Claims (1)

[Claims] 1. An R-section upper fixing plate is fixed to an end of a bridge girder, and an R-section lower fixing plate is installed below the R-section upper part, and a power cable laid on the bridge is radiused by the R-section upper fixing plate. Bend it at a right angle to R and lower it, and then fix it, and at the same time, bend it at a right angle to the radius R with the lower fixing plate of the R part and fix it, and give slack to the power cable at the falling part between the R part upper and lower fixing plates A method for expanding and contracting a bridge-installed power cable, characterized by expanding and contracting a bridge girder and expanding and contracting due to temperature changes in the power cable.