JP2004068332A - Tension fixing method of temporary cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and inexpensively fix the tension of a cable in a temporary erection used for erecting a PC bridge and release and removal. <P>SOLUTION: A pair of cables 14, 16 in a temporary structure are arranged in series in an upper floor slab 12 and respective one-side ends 14a, 16a of both serial directional sides are fixed to headers 12a, 12b of the upper floor slab 12 and then the other end 14b of one side temporary cable 14 is bent up to the upper floor slab 12 and fixedly insert to a movable fixing tool 20 and the other end 16b of the other temporary cable 16 is bent up and fixedly inserted in the fixing tool 20. In this condition, tension is guided into both the temporary cables 14, 16 by pulling out the other end 16b of the temporary cable 16. In this way, it is not necessary to conventionally construct a concrete fixing protrusion to the floor slab, nor labor and an expence for arranging rods, and chipping work. Further, the tension fixing for the cables 14, 16 is performed at one time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fixing a tension in a temporary cable used for erection of a PC bridge (prestressed concrete bridge).
[0002]
[Prior art]
When a PC bridge is erected, a so-called temporary cable may be used, in which a tension is introduced only during the erection and the tension is released when the erection is completed.
[0003]
To fix the tension in the temporary cable, place the temporary cable in the floor slab of the PC bridge in the middle of construction, fix one end of the cable to the edge of the floor slab, and then introduce tension into the temporary cable. The other end is fixed at a predetermined position on the floor slab.
[0004]
At this time, when the cable capacity is large, as shown in FIGS. 7 and 8 (a), a concrete fixing protrusion 102a is constructed on the floor slab 102, and a pair of serially arranged fixing protrusions 102a are arranged. The opposite end 104a of the temporary internal cable 104 is crossed over the fixing projection 102a to perform tension fixing, and after the installation is completed, the fixing projection 102a is peeled off, or as shown in FIG. 8B. A concrete fixing projection member 106 is fixed on the floor slab 102 with a plurality of PC steel materials 108, and the opposite ends 104a of a pair of temporary internal cables 104 arranged in series are crossed to the fixing projection 102a. A method is adopted in which the tension fixing is performed by hanging, and after the erection is completed, the fixing projection member 106 is removed.
[0005]
[Problems to be solved by the invention]
However, the method shown in FIG. 8A requires a lot of labor and cost for the rebar arrangement of the fixing protrusions 102a (arrangement of the reinforcing bars 110 and the like), the installation work, and the hanging work after the completion of the installation. There is a problem that the structure is often undesirably damaged. Also, in the method shown in FIG. 8B, there is a problem that much work and cost are required for fixing and removing the fixing projection member 106.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a tension of a temporary internal cable which can be easily and inexpensively fixed and fixed at a temporary internal cable used when constructing a PC bridge. It is an object to provide a fixing method.
[0007]
[Means for Solving the Problems]
The present invention achieves the above-mentioned object by using a movable fixing device to perform tension fixing on a pair of temporary cables arranged in series at once.
[0008]
That is, the tension fixing method of the temporary internal cable according to the present invention is as follows.
The temporary internal cable is arranged in the floor slab of the PC bridge in the middle of the erection, and one end of the temporary internal cable is fixed to the small opening of the floor slab. In the tension fixing method of the cable in the temporary, fixing the other end of the cable to a predetermined position of the floor slab,
After arranging the first and second temporary internal cables in series in the floor slab and fixing one end of each temporary internal cable on both ends in the series direction to the edge of the floor slab, The other end of the inner cable is bent up onto the floor slab and inserted and fixed in a movable fixing device, and the other end of the second temporary inner cable is bent up onto the floor slab and inserted into the fixing device. In this state, by pulling out the other end of the second temporary internal cable, tension is introduced to both the temporary internal cables.
[0009]
The “floor slab” may be an upper slab or a lower slab.
[0010]
The `` fixing device '' is configured so that each temporary internal cable is inserted in a substantially opposite direction to each other, and is configured to be displaceable on the floor slab when a tension is introduced. The specific configuration such as shape and material is not particularly limited.
[0011]
Operation and Effect of the Invention
As shown in the above configuration, the tension fixing method of the temporary internal cable according to the invention of the present application includes the first and second temporary internal cables arranged in series in the floor slab, each end of both sides in the serial direction of the floor slab. After being fixed to the fore edge, the other end of the first temporary internal cable is bent up onto the floor slab to be inserted and fixed in the movable fixing tool, and the other end of the second temporary internal cable is placed on the floor slab. Bending up and passing through the fixing device, and pulling out the other end of the second temporary cable in this state introduces tension into both the temporary cables. Can be obtained.
[0012]
That is, unlike the related art, there is no need to construct a concrete fixing projection on the floor slab or fix the concrete fixing projection member. Therefore, it is necessary to arrange, fix, and suspend the fixing projection. There is no need for an operation or an operation for fixing and removing the fixing projection member. Therefore, the labor and cost for this are not required, thereby shortening the construction period and reducing the cost.
[0013]
In addition, since tension fixing can be performed at once for a pair of temporary cables arranged in series, the number of work steps can be reduced by half as compared with the conventional case where tension is fixed for each temporary cable. In this regard, the construction period can be shortened and the cost can be reduced.
[0014]
As described above, according to the present invention, it is possible to easily and inexpensively carry out tension fixing, release, and removal of the intra-temporary cable used when constructing the PC bridge.
[0015]
In addition, in the present invention, since the movable fixing tool is used, it is possible to eliminate the possibility that the main body structure is undesirably damaged due to the hanging work of the fixing protrusion as in the related art.
[0016]
In the above configuration, if a guide jig for guiding the other end of each temporary cable to the fixing tool is arranged in the vicinity of both sides of the fixing tool in the serial direction on the floor slab, the inside of each temporary An unreasonable external force can be prevented from acting on the cable and the fixing device, so that the tension fixing operation can be performed smoothly. In addition, each of these guide jigs can be diverted when performing tension fixing work at another site.
[0017]
At this time, as each of these guide jigs, a slope-shaped guide portion for supporting the other end of each temporary internal cable from below, and a groove-shaped guide portion for preventing the other end of each temporary internal cable from laterally shifting. By using the one provided with the above, the tension fixing work can be performed more smoothly.
[0018]
Further, in the above configuration, a reinforcing bar for resisting a lifting force acting on each temporary internal cable at the time of the introduction of the tension is arranged at a position near the other end of each temporary internal cable in the floor slab. This can eliminate the possibility that the floor slab will be damaged when the temporary internal cable is tensioned and fixed.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a side view showing a PC bridge to which a method for tensioning and fixing a temporary internal cable according to an embodiment of the present invention is applied. FIG. 2 is a detailed sectional view of a portion II in FIG. 3 is a detailed view of a main part of FIG.
[0021]
The PC bridge 10 shown in FIG. 1 is a PC bridge being erected (during cantilever extension of the main girder), and a pair of temporary cables 14 and 16 arranged in series in the upper floor slab 12 are strained. FIG. 6 is a diagram illustrating a fixed state.
[0022]
The tension fixing work of these temporary internal cables 14 and 16 is performed as follows.
[0023]
That is, first, both the temporary internal cables 14 and 16 are arranged in series in the upper floor slab 12 along the bridge axis direction. The arrangement of these temporary internal cables 14 and 16 is performed by inserting the temporary internal cables 14 and 16 through a sheath 18 embedded in the upper floor slab 12. Each of these temporary internal cables 14 and 16 is composed of a plurality (six) of PC steel strands.
[0024]
Then, one end portions 14a, 16a on both sides in the serial direction (both sides in the bridge axis direction) of the respective temporary internal cables 14, 16 are fixed to the small openings 12a, 12b of the upper floor slab 12 by wedges. On the other hand, the other end portions 14b and 16b of the temporary internal cables 14 and 16 are bent up and are projected obliquely upward from the cable outlets 12c and 12d of the upper floor slab 12.
[0025]
Then, the other end 14b of one temporary internal cable 14 (first temporary internal cable) is inserted and fixed (wedge-fixed) to the fixing device 20 on the upper floor slab 12, and the other temporary internal cable 16 (second internal cable) is fixed. The other end 16 b of the temporary internal cable) is inserted through the fixing device 20.
[0026]
In this state, the other end 16b of the temporary internal cable 16 is pulled out by the jack 24 attached to the fixing device 20 via the R chair 22, thereby introducing tension to both the temporary internal cables 14, 16. After the introduction of the tension is completed, the other end 16b of the temporary internal cable 16 is wedge-fixed to the fixing device 20, the R chair 22 and the jack 24 are removed, and the tension fixing operation is completed.
[0027]
The fixing device 20 is a movable steel fixing device, and is configured as a so-called cross-fixing device. That is, the fixing device 20 is formed in a box shape, and the respective temporary internal cables 14 and 16 are inserted in opposite directions, and the other end portions 14b and 16b of the respective temporary internal cables 14 and 16 are connected at both end surfaces. It has become established.
[0028]
Since the fixing device 20 is movable, it is displaced in the bridge axis direction with the introduction of tension. That is, in FIG. 3, the cable is to be displaced leftward due to the tension of the temporary internal cable 14, and is also displaced leftward when the temporary internal cable 16 is pulled out. Therefore, finally, the introduction of the tension is completed at a position displaced leftward by a predetermined amount from the original position (the position indicated by the two-dot chain line).
[0029]
After the installation of the PC bridge 10 is completed, the tensions of the two temporary cables 14 and 16 thus fixed in tension are released and removed from the upper floor slab 12. At that time, the release of the tension is performed by attaching the R chair 22 and the jack 24 to the fixing device 20 again.
[0030]
In the present embodiment, when performing the above-described tension fixing operation, the other end portions 14b and 16b of the respective temporary internal cables 14 and 16 are guided to the fixing device 20 on both sides in the bridge axis direction of the fixing device 20 on the upper floor slab 12. Guide jig 26 is arranged in advance.
[0031]
Each of these guide jigs 26 is a steel jig, and as shown in FIG. 4 alone, the other end of each of the temporary internal cables 14 and 16 projecting obliquely from inside the upper slab 12 onto the upper slab 12. A configuration having a slope-shaped guide portion 26a for supporting the portions 14b and 16b from below, and a groove-shaped guide portion 26b for preventing the other end portions 14b and 16b of the temporary cables 14 and 16 from laterally shifting. ing.
[0032]
The inclined guide portion 26a is formed in a convex curved shape, and thereby supports the respective temporary internal cables 14, 16 over a predetermined length. Further, the concave groove guide 26b is formed in a U-shape at the upper end of the slope of the slope guide 26a.
[0033]
Further, in the present embodiment, as shown in FIG. 2, when the upper floor slab 12 is driven, portions near the other end portions 14 b and 16 b of the respective temporary internal cables 14 and 16 in the upper floor slab 12 (specifically, In the upper floor slab 12, reinforcing bars 28 for resisting the lift acting on the respective temporary internal cables 14 and 16 at the time of the introduction of the tension are disposed at the cable protrusions 12 c and 12 d of the upper floor slab 12 near the bridge axial direction. It is supposed to keep. A plurality (three) of the reinforcing bars 28 are arranged for each of the cable protrusion ports 12c and 12d.
[0034]
These reinforcing bars 28 straddle the sheath 18 as shown in FIG. 5 (a) which is a detailed view of the Va portion in FIG. 2 and FIG. 5 (b) which is a cross-sectional view taken along line Vb-Vb in FIG. 5 (a). And a pair of linear portions 28b extending horizontally from the lower end of the inverted U-shaped portion 28a toward the cable outlet 12d (12c). ing.
[0035]
As described in detail above, in the present embodiment, one end portions 14a, 16a on both sides in the bridge axis direction of the pair of temporary internal cables 14, 16 arranged in series in the upper floor slab 12 along the bridge axis direction. Are fixed to the edges 12a, 12b of the upper floor slab 12, then the other end 14b of one of the temporary internal cables 14 is bent up onto the upper floor slab 12, and is fixedly inserted into the movable fixing device 20 while the other is fixed. The other end 16b of the temporary internal cable 16 is bent up onto the upper floor slab 12 and inserted into the fixing device 20, and in this state, the other end 16b of the temporary internal cable 16 is pulled out, thereby tensioning the two temporary internal cables 14,16. Since the force is introduced, the following operation and effect can be obtained.
[0036]
That is, unlike the related art, there is no need to construct a concrete fixing projection on the floor slab or fix the concrete fixing projection member. Therefore, it is necessary to arrange, fix, and suspend the fixing projection. There is no need for an operation or an operation for fixing and removing the fixing projection member. Therefore, the labor and cost for this are not required, thereby shortening the construction period and reducing the cost.
[0037]
Further, since the tension and fixing of the pair of temporary cables 14 and 16 arranged in series can be performed all at once, the number of work steps is reduced as compared with the conventional case where the tension and fixing are performed for each temporary cable individually. In this respect, the construction period can be shortened and the cost can be reduced.
[0038]
As described above, according to the present embodiment, tension fixation, release, and removal of the temporary cables 14, 16 used when the PC bridge 10 is erected can be easily and inexpensively performed.
[0039]
In addition, in the present embodiment, since the movable fixing device 20 is used, there is no possibility that the main body structure is undesirably damaged by the hanging operation of the fixing protrusion as in the related art. .
[0040]
Further, in the present embodiment, a guide jig for guiding the other end portions 14b, 16b of the respective temporary internal cables 14, 16 to the fixing device 20 at portions near both sides in the bridge axis direction of the fixing device 20 on the upper floor slab 12. 26 is arranged, it is possible to prevent an unreasonable external force from acting on each of the temporary internal cables 14 and 16 and the fixing device 20, and thus the tension fixing operation can be performed smoothly. . In addition, each of these guide jigs 26 can be diverted when performing tension fixing work at another site.
[0041]
At this time, in the present embodiment, as the respective guide jigs 26, the other end portions 14b, 16b of the respective temporary internal cables 14, 16 projecting obliquely from within the upper floor slab 12 onto the upper floor slab 12 are supported from below. Since the one having the slope-shaped guide portion 26a and the groove-shaped guide portion 26b for preventing the other end portions 14b, 16b of the respective temporary internal cables 14, 16 from laterally shifting is used, the tension fixing work is further improved. It can be done smoothly.
[0042]
Further, in the present embodiment, the upper floor slab 12 is provided with a portion in the vicinity of both sides of the cable protruding ports 12c and 12d in the bridge axis direction in order to resist lift acting on the respective temporary internal cables 14 and 16 at the time of introducing the tension. Since the reinforcing bars 28 are arranged, it is possible to eliminate the possibility that the upper slab 12 is damaged when the temporary internal cables 14 and 16 are fixed in tension. In the present embodiment, it has been described that three cables are provided for each of the temporary cables 14 and 16, but four or more cables may be provided, or two or less cables may be provided. Is also good.
[0043]
By the way, in the present embodiment, the case where the temporary internal cables 14 and 16 arranged in the upper floor slab 12 are tensioned and fixed during the erection of the PC bridge 10 by cantilevering the main girder, In other cases, the tension fixing method of the temporary cable according to the present embodiment can be applied.
[0044]
For example, as shown in FIG. 6, during the construction of the PC bridge 40 by the extrusion method, the pair of temporary cables 14 and 16 arranged in the lower floor slab 42 can be tensioned and fixed.
[0045]
In this case, as shown in FIG. 3A, when pushing out in the direction of the arrow in the drawing with the hand-extended girder 44 attached to the distal end, the temporary internal cables 14 and 16 are maintained in a tension-fixed state. As shown in FIG. 13B, after the extrusion is completed, the tension of the pair of temporary internal cables 14 and 16 may be released, and these may be removed from the lower floor slab 42.
[Brief description of the drawings]
FIG. 1 is a side view showing a PC bridge to which a tension fixing method for a temporary internal cable according to an embodiment of the present invention is applied. FIG. 2 is a detailed sectional view of a portion II in FIG. 1 FIG. FIG. 4 is a diagram showing the guide jig used in the above embodiment as a single item. FIG. 5 is a detailed view of the Va portion in FIG. 2 (a) and a cross-sectional view of the same taken along line Vb-Vb (b).
6 is a view similar to FIG. 1 showing a modification of the above embodiment; FIG. 7 is a view similar to FIG. 1 showing a conventional example; FIG. 8 is a view showing the above conventional example; FIG. (A) and FIG. (B) similar to (a) showing another conventional example.
[Explanation of symbols]
10 PC bridge 12 Upper floor slab (floor slab)
12a, 12b Small mouth 12c, 12d Cable outlet 14 Temporary internal cable (first temporary internal cable)
14a, 16a One end 14b, 16b Other end 16 Temporary internal cable (second temporary internal cable)
18 Sheath 20 Fixing tool 22 R chair 24 Jack 26 Guide jig 26a Slope guide 26b Groove guide 28 Reinforcing bar 28a Inverted U-shaped section 28b Straight section 40 PC bridge 42 Lower deck (floor deck)
44 Tenobu girder

Claims (4)

The temporary internal cable is arranged in the floor slab of the PC bridge in the middle of the erection, and one end of the temporary internal cable is fixed to the small opening of the floor slab. In the tension fixing method of the cable in the temporary, fixing the other end of the cable to a predetermined position of the floor slab,
After arranging the first and second temporary internal cables in series in the floor slab and fixing one end of each temporary internal cable on both ends in the series direction to the edge of the floor slab, The other end of the inner cable is bent up onto the floor slab and inserted and fixed in a movable fixing device, and the other end of the second temporary inner cable is bent up onto the floor slab and inserted into the fixing device. And tensioning the two temporary cables by pulling out the other end of the second temporary cable in this state. A guide jig for guiding the other end of each of the temporary internal cables to the fixing tool is disposed at a position near the both sides of the fixing tool in the serial direction on the floor slab. Item 2. The tension fixing method of the temporary internal cable according to Item 1. As each of the guide jigs, a slope-shaped guide portion that supports the other end of each of the temporary cables from below, and a groove-shaped guide portion that prevents the other end of each of the temporary cables from laterally shifting. The tension fixing method for a temporary internal cable according to claim 2, wherein a cable provided is used. A reinforcing bar for resisting a lift acting on each of the temporary cables at the time of the introduction of the tension is disposed at a position near the other end portion of each of the temporary cables in the floor slab. The tension fixing method for a temporary internal cable according to claim 1.

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