JPS6359706A - Method of installing power cable on bridge end - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for laying power cables at the end of a bridge, and more specifically, a method for laying a power cable to the ground from the end of a bridge where expansion and contraction and angle changes occur. It is about the method.

<Background of the invention and problems> Normally, at the end of a small-scale bridge with a short span, expansion and contraction occurs mainly due to temperature changes in the girder, and the amount of expansion and contraction is small, for example, about 50 to 100n. ,
Recently, large-scale bridges with long spans such as suspension bridges and cable-stayed bridges have become more common.
A large expansion and contraction of about 77L occurs, and angle changes in the horizontal and vertical directions (hereinafter referred to as corner bending) occur.

In addition, most of the corner bends are about 1 to 3 degrees.

When lowering power cables to the ground from the bridge ends of such large-scale bridges, even if there is a relative displacement between a moving point on the bridge and a fixed point on the ground, there will be no local strain on the power cables. It is necessary to avoid bending or twisting.

Conventionally, there has been no suitable method of laying power cables at the bridge ends that simultaneously absorbs the expansion and contraction of the bridge as well as corner bends, and with the increase in large-scale W beams, the effectiveness of laying power cables at the bridge ends has become increasingly difficult to find. At present, proposals for new methods are awaited.

<Purpose of the Invention> This invention has been made in view of the above points, and aims to reduce the degree of deformation of the power cable by simultaneously absorbing the expansion and contraction of the bridge and corner bending in the power cable installation area at the remote end. The purpose of this invention is to provide a method for laying power cables at the end of a bridge.

Means for Achieving the Object> In order to achieve the above object, the present invention provides a bridge structure in which an attachment frame is provided with a slack part that can be bent and expanded and contracted by connecting with a hinge so that it can be moved in the longitudinal direction of the bridge. one end of the auxiliary frame located on the bridge end side and the ground fixing point on the bridge end side is kept at a certain distance by a support, the other end of this auxiliary frame is fixed on the bridge, and the above-mentioned One end of the auxiliary frame and the ground are connected by an arch frame in which the frame bodies are sequentially connected with three hinges, the lowest hinge point of this arch frame is fixed to the ground, and the power cable drawn from the end of the bridge to the ground is connected to the ground. The power cable is laid from inside the support frame along the inside of the arch frame, and is made to follow the deformation of the support frame and arch frame caused by expansion and contraction of the bridge and changes in angle.

<Function> When a bridge expands or contracts in the longitudinal direction, the slack part of the support frame is deformed because the support points of the support columns are fixed, and the bending radius of the power cable uniformly changes to follow this slack part. It also absorbs the expansion and contraction of the bridge.

When a corner bend occurs at the end of the bridge, the displacement is applied to the upper end of the arch frame, the arch frame bends and deforms at each hinge, and the power cable changes to follow the deformation of the arch frame. Absorbs corner bends.

<Example> Hereinafter, an example of the present invention will be described based on the accompanying drawings.

As shown in Figures 1 to 3, the attachment frame 2 installed near the end of the bridge 1 connects a plurality of frames 2a to 2e sequentially with hinges 3a to 3d, and can be bent in the horizontal direction. It is supported by a sliding plate 4 so as to be slidable in the longitudinal direction of the bridge 1.

The attachment frame 2 is provided with a slack part 5 in the middle that can be expanded and contracted while being bent, and the frame body 2e at one end located near the end of the bridge 1 is provided with connection ports in two directions at right angles. A support 6 is interposed between the frame body 2e and the ground-side fixed point facing the bridge end, and a constant distance is maintained between the frame body 2e and the ground-side fixed point.

In the attached frame 2, a frame body 2 located on the inner side of the bridge 1
A is fixed on the bridge 1 by the fixing member 7, and when the bridge 1 expands or contracts, this frame 2a moves by the amount of expansion or contraction, and the frame 2a moves between it and the immovable frame 2e fixed to the support column 6. , the attachment frame 2 absorbs the expansion and contraction of the bridge 1 by expanding and contracting the slack portion 5.

Note that the frame body 2e is fixed to the bridge 1 by guide rails 8 to prevent sideways movement.

The arch frame 9 connecting the frame 2e of the supporting frame 2 to the ground connects the frames 9a, 9b and 9C sequentially with hinges 10b and 11c, and connects the uppermost frame 9a to the frame 2e with the hinge 10.
a, and a total of three hinges 10a, 110b, 10c
It has a link structure in which the frame bodies 2e, 9a to 9c are connected so as to be bendable in the width direction of the Ia beam 1.

When the arch frame 9 is viewed from above, it is a straight line as shown in Figure 2, and when viewed from the side, it is circular as shown in Figure 3.
A pair of hinges 10a, 10b, and 10c are attached to each side of each frame, and the lowest hinge 10c is erected on the ground and supported by a jζ support 11, serving as a fixed point.

The power cable A that is lowered to the ground from above the bridge 1 is laid along the inside of the support frame 2 and the inside of the arch frame 9.

The power cable A in the attachment frame 2 is as shown in Figure 2.
The cleats 12a, 12b and 112c are installed to create slack along the shape of the slack portion 5, and the frame 2a,
Fixed to 2G and 2e.

Further, the power cable A within the arch frame 9 is laid so as to have an arc shape when viewed from the side as shown in FIG. 3, and a snake shape when viewed from the top and front as shown in FIGS. 1 and 8.
It is fixed to each of the frames 2e, 9a to 9C by cleats 13a to 13d, and further supported by rollers 14 at positions between the cleats.

The reason why the rollers 14 are distributed and the support spacing of the power cables A is made similar is to raise the natural vibration frequency of the cable system so that the power cable A does not resonate with the vibration transmitted from the bridge end. This is a consideration for the purpose of doing so.

The power cable installation method of the present invention is carried out by laying the power cable A along the @-built attachment frame 2 and arch frame 9 as described above, and then absorbing the expansion/contraction and corner bends that occur in the bridge 1. explain.

As shown in Figure 4, if the bridge 1 begins to extend by 6M in the direction of arrow B in the figure, the frame 2e supported by the columns 6 of the supporting frame 2 remains stationary, while Since the frame 2a fixed to the bridge 1 moves by 6M together with the bridge 1, the slack portion 5 is deformed as shown by the dotted chain line in the figure by the link mechanism of the hinges 3a to 3d.

At this time, the cleats 12a to 12c that fix the power cable A to each frame move in the same way as the frame moves, so the bending radius of the power cable A changes uniformly to correspond to the elongation of the bridge 1. Become.

In addition, since the frame body 2e of the auxiliary frame 2 is stretched by the pillars 6, the power cable A is
This is handled by the slack on the bridge 1, and the arch frame 9 is not affected at all.

Corner break absorption As shown in Figure 5, if a horizontal corner break occurs in beam 4 by △θ with the center point of the bridge end as the fulcrum, -
In the supporting frame 2, the frame body 2a is fixed to the bridge 1 by the fixing member 7, and the frame body 2e is prevented from moving sideways by the guide rail 8. A displacement will be applied to the upper end of the arch frame 9.

Strictly speaking, the sizes of ΔN+ and ΔN2 are slightly different, but
Since Δθ is small, they can be considered to be approximately equal.

In addition, without the guide rail 8, the frame body of the slack portion 5 of the attachment frame 2 would sway sideways, making it unstable against earthquakes, winds, etc., and bending the power cable at the fixed member. This is not preferable because it causes the arch frame 9 to be displaced more than designed.

Similarly, a vertical displacement is applied to the upper end of the arch frame 9 for a vertical corner bend.

The absorption principle of these vertical and horizontal changes is shown in Figures 6 and 7.
As shown in the figure.

Figure 6 shows absorption for horizontal corner bends,
Since the lengths of the frames 9a, 9b between the hinges 10a, 10b, and 10c do not change with respect to ΔN, the hinge position after the change is determined geometrically, and it suffices if it takes a shape like the broken line.

Figure 7 shows the absorption of vertical corner bends.
The same applies to 8H as in the case of FIG.

Here, the distance between the fixed cleats 13b and 13c is from S to S.
', and the power cable itself also expands and contracts due to temperature changes, but by laying the snake in the horizontal direction of the power cable A, the length change between the cleats can be absorbed by the snake width change.

<Effects> As described above, according to the present invention, an arch frame is provided between the attachment frame attached to the end of the A-beam and the ground, and a power cable is attached along the attachment frame and the arch frame. It will be possible to lower power cables to the ground while simultaneously absorbing expansion, contraction, and corner bends at the ends.

In addition, by absorbing expansion/contraction and corner bends in separate locations, the degree of deformation of the power cable is reduced, and since the arch frame using three hinges is a link mechanism, the vertical and horizontal directions that occur due to corner bends are reduced. It can smoothly follow the displacement of the bridge, and does not exert unnecessary reaction force on the bridge girder.

Furthermore, the three-hinged arch frame becomes a stable structure against its own weight and external forces applied during earthquakes and typhoons, and by taking the horizontal snake of the power cable within the arch frame, thermal expansion of the white of the power cable and the arch frame are prevented. Changes in distance between hinges due to changes in can be absorbed by changes in snake width.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the installation state of the installation method according to the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a side view of the same, FIG. The figure is a plan view explaining the absorption of corner folds, Figure 6 is an explanatory diagram showing the absorption of horizontal corner folds of the arch frame, Figure 7 is an explanatory diagram also showing the absorption of vertical corner folds, and Figure 8 is an explanatory diagram of the arch frame. FIG. 3 is a developed view showing a state in which power cables are installed in the frame.

Claims (2)

[Claims] (1) An attachment frame with a slack part that can be bent and expanded and contracted by connecting with a hinge is installed on the bridge so that it can be moved in the longitudinal direction of the bridge, and one end of the attachment frame is located on the bridge end side. The other end of this attachment frame is fixed on the bridge, and three hinges are used to connect one end of the attachment frame to the ground. The frames are connected by an arch frame that is connected in sequence, the lowest hinge point of this arch frame is fixed to the ground, and a power cable that is drawn out from the bridge end to the ground is laid along the inside of the arch frame from within the attached frame. A method for laying power cables at the end of a bridge, characterized by making the power cable follow the deformation of the support frame and arch frame caused by expansion/contraction and angle changes. (2) The power cable installation method at the end of a bridge according to claim 1, wherein the power cable is installed in a snake shape within the arch frame and is fixed to each frame.