JP2009068333A - Handling method of prefabricated cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a handling method of a prefabricated cable capable of obtaining a prefabricated cable which enables each tension member to be tensioned. <P>SOLUTION: A prefabricated cable 100, wherein a plurality of tension members are arranged in a sheath in parallel, is prepared. The prefabricated cable 100 is sequentially dropped onto a fixed tray 160 from one end, and wound on the tray in such a manner that substantially one-time twist per winding of the prefabricated cable 100 is introduced into the cable. In the construction of the cable, the cable 100 is pulled out upward from the side of the other end so that the twist of the introduced cable 100 is untreaded. The pulled out cable 100 is released from the twist and each tension member can be returned to a parallel state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for handling a prefabricated cable used for a bridge, a prestressed concrete (PC) structure, or the like. In particular, the present invention relates to a prefabricated cable handling method in which a prefabricated cable having a plurality of tendons and capable of being tensioned for each tendon is obtained.

  Multi-strand prefabricated cables are used as slant cables for long-span bridges, suspension cables for suspension bridges, prestressed cables for prestressed concrete structures, and the like (for example, Non-Patent Document 1).

  In general, a prefabricated cable is a cable in which a necessary number of tension members are cut and bundled in advance to a predetermined length in a factory in order to shorten the construction time on site. As a specific example, a plurality of resin-coated PC steel strands that become tendons are converged, a filler is placed along the converging body, a substantially circular cross section is formed, and a resin-coated sheath is provided on the outer periphery. The provided structure is mentioned. Since such a prefabricated cable is manufactured at a factory and carried into a construction site, the prefabricated cable is wound around a drum or wound into a coil. In this winding state, if the tension members are arranged in parallel in the sheath, a difference between the inner and outer diameters of the winding diameter occurs between the tension members, which leads to the tension material variation. The tendon is twisted and configured as a bundling body.

  An example of the manufacturing procedure of this prefabricated cable will be described with reference to FIGS. First, as shown in FIG. 5, the tendon material 10 (resin-coated PC steel stranded wire) is fed from the supply device 200 and fed to the downstream measuring device 220 by the feeding device 210. The measuring device 220 measures a predetermined standard length from the traveling tendon 10. The tendon material 10 is cut by the cutting device 230 so as to have this fixed length. Each tension material 10 having a fixed length is inserted into the pipe twister 240. The pipe twister 240 has a configuration in which a plurality of hollow pipes are converged.

  Next, as shown in FIG. 6, the tendon material in the pipe twister 240 is pulled out and inserted into the eyeplate twister 250. In this state, the pipe twister 240 and the eye plate twister 250 are rotated to impart twist to the plurality of tendons 10. The tendon 10 delivered in a twisted state is introduced into the voice 270 together with the filler 20 fed out from the filler supply 260 and formed into a circular cross section. Subsequently, the obtained molded body is wound with a tape by a lapping device 280 and wound on a winding drum 290.

  Further, as shown in FIG. 7, the tension material 11 wrapped with the take-up drum 290 as a supply is fed out by a pinch roller 300, introduced into an extruder 310, and coated with a resin to form a sheath. Thereafter, the tendon 12 having a sheath is introduced into the water-cooled tank 320 to harden the coating, and is further wound around the winding drum 340 via the pinch roller 330.

  In addition, field construction cables are also known as cables other than prefabricated cables. This on-site construction type cable inserts tension materials one by one into the sheath tube and performs the tension and fixing work, and then repeats the insertion, tension and fixation of the tension materials in the same manner, and multiple tension wires are inserted into the sheath tube. This constitutes a state in which the materials are arranged in parallel. Then, the clearance between the sheath tube and the tendon is filled with cement milk to prevent corrosion.

Sumitomo Electric Steel Wire Co., Ltd. Product catalog “New PC Materials & engineering” P.9 Published October 2002

  However, the above prior art has the following problems.

<Conventional prefabricated cable>
(1) Tension work cannot be performed for each tension material.
Since each tendon is twisted in the sheath, the degree of freedom in which the individual tendons are independently extended in the longitudinal direction is small. Therefore, even if it tries to perform the tension work for each tension material, the tension force cannot be transmitted to the entire length of the tension material. As a result, the tension work of this prefabricated cable requires a large jack that can tension all the tension members in a lump, and the tension work becomes large.

(2) The manufacturing equipment is large, the manufacturing work is not easy, and the product is expensive.
In order to impart twist to a plurality of tendons, a large-scale manufacturing facility such as a pipe twister is required. The work of inserting the tendon material into the pipe of this pipe twister is a time-consuming work because it is performed against the friction between the pipe and the tendon material. In addition, in the manufacturing process, three processes, that is, a constant length cutting of the tendon, twisting with a pipe twister, and sheath coating, must be performed, and the equipment burden is very large. Further, in order to impart the twisting process, the length of the tension material is required to be longer than that of a straight line that does not impart torsion. As a result, the product cost is increased.

(3) A long prefabricated cable cannot be obtained.
Since the obtained prefabricated cable is restricted by the length of the pipe twister, a long prefabricated cable cannot be obtained. If the length of the pipe twister is increased, a long prefabricated cable can be obtained. However, the production line becomes very long, and the work of inserting the tension material into the pipe becomes more difficult, which is a practical production means. hard. Considering the practicality of this insertion work, the unit length of the prefabricated cable obtained is limited to about 250 to 300 m.

<On-site construction type cable>
(1) Construction work is extremely complicated.
On-site construction type cables can be tensioned with a small jack for each tension member. However, in order to assemble the cables themselves on site, it is necessary to insert tension members one by one into the sheath tube and repeat the tension and fixation, which complicates a very complicated and time-consuming operation and increases the construction cost. In addition, after inserting a plurality of tendons into the sheath tube and tightening and fixing it, it is usually necessary to inject cement milk into the sheath tube. In particular, the injection work in a cold region further increases the burden.

(2) The cable diameter is large, which is not preferable from the viewpoint of wind resistance.
A sheath that allows sufficient clearance between the tendon and the sheath tube in consideration of the ease of insertion and injection, because the tendon is sequentially inserted into the sheath tube one by one at the site and cement milk is injected later. It is necessary to prepare a tube. For this reason, the assembled cable diameter (outer diameter of the sheath tube) must be increased, which is disadvantageous because the wind pressure resistance increases when used for a bridge cable.

  Accordingly, a main object of the present invention is to provide a method for handling a prefabricated cable in which the tension material is twisted in a wound state during conveyance, and the tension material is easily untwisted when pulled out.

  Moreover, the prefabricated cable which can be tensioned for each tension material is provided.

  Furthermore, the manufacturing method of the prefabricated cable which can be easily manufactured with simple equipment is provided.

  The present invention achieves the above object by providing a prefabricated cable in which a plurality of tendons are not twisted in a sheath, and devising a method for forming a shipping form of the prefabricated cable and a handling method at a construction site.

  The method for handling a prefabricated cable according to the present invention is a method for handling a prefabricated cable having a plurality of tendons and a sheath for arranging and accommodating these tendons in parallel. A prefabricated cable wound from one end of the cable is prepared so that one twist is introduced into the prefabricated cable. Thereafter, the other end side of the prefabricated cable is drawn upward so that the twist of the introduced prefabricated cable returns.

  For the preparation of the prefabricated cable, the following prefabricated cable manufacturing method can be preferably used. The manufacturing method includes a step of drawing out tension members from a plurality of supply drums, collecting the tension members and arranging them in parallel, a step of coating a sheath on the outer side of the tension members, and forming a prefabricated cable. And sequentially winding the prefabricated cable onto the fixed tray from the side and winding the prefabricated cable so that substantially one twist is introduced into the cable for each turn of the prefabricated cable on the tray.

  Moreover, the following prefabricated cables are obtained by the manufacturing method. This prefabricated cable is a prefabricated cable that is installed with both ends fixed to a structure in a tension state. This cable has a plurality of tendons and a sheath that collects and stores these tendons. And each tendon is parallel along a longitudinal direction.

  Here, any one of bare PC steel strand, plated PC steel strand, resin-coated PC steel strand, and unbonded PC steel strand can be suitably used as the tension material. Examples of the plated PC stranded wire include a galvanized PC steel stranded wire. Epoxy, polyethylene, polycarbonate, polyester, etc. can be used for resin coating of resin-coated PC steel strands. In addition to the case where the resin coating is formed only on the outer periphery of the strand of PC steel, there are cases where the resin is filled between the strands. In addition, a structure in which a resin coating is formed for each element wire and the resin-coated element wires are twisted together may be employed. Higher anticorrosion properties can be obtained with the wire than PC steel with plating or resin coating. The unbonded PC steel strand has a configuration in which the PC steel strand is accommodated in the sheath portion, and grease or the like is filled between the sheath portion and the PC steel strand.

  Each tendon preferably has an identification mark for identifying each other. In the above cable, since the tension members are arranged in parallel in the sheath, it is possible to perform tension work independently for each tension member. At that time, if some kind of identification mark is provided so that the tendons can be distinguished from each other, the present tendon to be tensioned is not mistaken. When the identification mark is a bare PC steel wire or a plated PC steel wire, it can be partially coated and used as an identification mark according to the shape or color of the mark. In the case of a resin-coated PC steel wire or an unbonded PC steel wire, an identification mark can be formed by color-coding the resin coating or the sheath portion in addition to the marking or printing of the mark on the resin coating or the sheath portion.

  Such tendons are arranged in parallel within the sheath. For this reason, each tendon can be easily extended in the longitudinal direction independently, and can be tensioned for each tendon with a small jack. According to the above-described method of handling the present invention, the cable is in a state of being wound up from shipping to immediately before being used on site, and during that time, the tension material is in a twisted state. The torsion of the tendon is released and returned to the parallel state in the sheath. Therefore, it is also possible to avoid the tension material from being scattered due to the difference between the inner and outer diameters of the winding diameter between the tension materials during conveyance.

  The sheath material of the prefabricated cable is preferably a material having excellent mechanical strength and weather resistance. For example, polyolefin resin such as polyethylene is suitable. In particular, the weather resistance can be improved by adding carbon black. The added amount is preferably about 2 to 3% by weight.

  Furthermore, it is preferable to arrange a filler on the outer periphery of the tendon as necessary, and to make the cross-sectional shape of the complex of the tendon and the filler circular. Usually, the cross-sectional shape is not circular in the state where the tendons are arranged in parallel. By combining the filler with the tendon, the cross-sectional shape of the composite can be made circular, and the sheath can be smoothly formed on the composite.

  If a plurality of tendons are gathered and arranged in parallel, and a sheath is formed outside the tendons, a prefabricated cable in which no twist is imparted to the tendons within the sheath can be obtained. Subsequently, the prefabricated cable is dropped from the upper side to the lower side and wound around the fixed tray in a spiral shape. Examples of the fixed tray include those having a winding drum in the vertical direction. A turn is formed by winding the winding start end of the dropped cable along the outer periphery of the winding drum, and the sequentially dropped cable is wound around the outer periphery of the adjacent turn, and the cable is wound in a spiral shape. . By this winding, in a state where the cable is wound, it is possible to form a state in which twist is applied to the tension material in the sheath. This twist is caused by dropping the cable and setting the winding start end to the inner peripheral side and winding it so that it gradually spreads to the outer peripheral side, so that substantially one twist per one turn is naturally applied to the tension material. can get.

  Therefore, according to this manufacturing method, a prefabricated cable in which a plurality of tendons are arranged in parallel in the sheath is manufactured, and the manufactured cable is wound up in a shipping form in which twist is applied to the tendons. This can be done on the production line.

  Normally, when the first layer spiral cable reaches a predetermined outer diameter by the above winding, the second layer is laminated on the first layer and wound from the outer peripheral side to the inner peripheral side. Similarly, the third and subsequent windings are performed. Of course, it is also possible to wrap the cable by cutting the cable for each layer and laminating spiral cables in multiple layers.

  If necessary, a compounding step of fillers may be combined between the step of arranging the tension members in parallel and the step of covering the sheath. By this composite process, the cross section of the composite of the tendon material and the filler is formed into a substantially circular shape. Further, a step of lapping the composite with tape may be added before the sheath covering step. By this wrapping, the composite is prevented from being scattered.

  The prefabricated cable prepared by the above manufacturing method is wound in a state where one twist is applied to each turn of the cable at the time of conveyance. Therefore, when the wound cable is pulled upward from the winding end side, the twist is naturally released and each tension material is restored to a straight shape in the sheath. Therefore, it is not necessary to use special equipment or a method for releasing the twist of the tendon applied in the wound state, and thereafter, the construction work can be immediately started.

[A] According to the method of handling a prefabricated cable of the present invention, the following effects can be obtained.
(1) By simply pulling up the prefabricated cable with one twist applied to each turn of the prefabricated cable, the twist that was introduced can be restored. It is possible to return to the correct state.

[B] According to the prefabricated cable, the following effects can be obtained.
(1) Since the tension members are arranged in parallel, the tension members can be tensioned with jacks, and the tension work can be performed with a relatively small jack.

    (2) Since each tendon is parallel, the length of each tendon can be saved compared to a cable in which twist is introduced by a pipe twister.

    (3) The diameter can be reduced compared to the field-installed cable, and the cable can be made with low wind resistance.

    (4) By providing an identification mark for identifying each of the tendons, when tensioning is performed for each of the tendons, it is possible to avoid misidentification of the tendons to be tensioned.

[C] According to the manufacturing method of the prefabricated cable, the following effects can be obtained.
(1) Since each tendon is arranged in parallel, it is not necessary to introduce twist to each tendon with a pipe twister, and the length of the product is not restricted by the length of the pipe twister. Manufacturing is possible.

    (2) Prefabricated cables can be manufactured at low cost with simple equipment without the need for large-scale production equipment such as pipe twisters.

    (3) By simply winding the prefabricated cable in a spiral shape, one twist can be introduced for each turn of the prefabricated cable, and the winding state can be made unaffected by the difference between the inner and outer diameters of the wound diameter.

    (4) It is possible to perform a series of lines from feeding a plurality of tendons to covering the sheath and then winding the prefabricated cable into a shipping form, thereby greatly simplifying the manufacturing equipment.

(Prefabricated cable configuration)
A configuration of a prefabricated cable that can be tensioned with a jack for each tension material will be described.

  As shown in FIG. 1, the prefabricated cable 100 includes a plurality of tension members 10 arranged in parallel, a filler 20 combined with an assembly of the tension members 10, and a composite of the tension members 10 and the filler 20. And a sheath 30 formed on the outer periphery of the.

  For each tendon 10, a resin-coated PC steel strand was used. The PC steel strand is a JIS G 3536 SWPR7BN seven strand twisted wire (one center wire + six side wires), and is a 15.2 mm diameter PC steel wire. The resin coating is formed by powder coating an epoxy resin with a film thickness of about 0.6 mm. The coating resin was filled in the gaps between the strands so that sufficient anticorrosion properties were obtained.

  Fillers 20 are combined with these tendons 10 assembled in parallel. The filler 20 is used to form a cross-sectional shape of the composite in a circular shape by being combined with the tendon 10. In this example, a polypropylene wire was used for the filler 20.

  A sheath 30 is covered with the composite of the tendon 10 and the filler 20. In other words, the PC steel strand is double protected by the resin coating and the sheath. The sheath 30 was made of polyethylene to which carbon black was added.

(Prefabricated cable manufacturing method)
Next, the manufacturing method of the said prefabricated cable is demonstrated based on FIG.

  FIG. 2 is a schematic view of the cable production line shown in FIG. In this line, a plurality of supply drums 110, a collective processor 120, a filler supply 130, an extruder 140, a water cooling tank 150, and a fixed tray 160 are arranged in this order from the upstream side.

  Each of the supply drums 110 is wound with a resin-coated PC steel wire that becomes the tendon material 10, and the tendon material 10 is fed out from each drum 110. The number of drums 110 may be set as appropriate according to the number of tension members 10 to be assembled. In general, 19 or 27 tendons 10 are often used.

  The tendon members 10 fed out from the supply drum 110 are introduced into the collective processor 120 and assembled there. Subsequently, the filler 20 is introduced into the filler supply 130, and the filler 20 is combined with the outer periphery of the assembly of the tendon 10. Between the supply drum 110 and the filler supply 130, the gathered tendons 10 are not twisted at all, and the tendons 10 are held in parallel.

  Next, the composite of the tendon 10 and the filler 20 is introduced into the extruder 140. In this extruder 140, polyethylene resin is extruded and coated on the composite. The sheath coated with extrusion is introduced into the water-cooled tank 150 and cured to form the prefabricated cable 100.

  The obtained prefabricated cable 100 is dropped onto the fixed tray 160, wound up in a spiral shape, and formed into a shipping form. FIG. 2 shows the fixed tray 160 as viewed from above. The winding procedure by this dropping will be described in more detail with reference to FIG.

  The prefabricated cable 100 obtained through the water-cooled tank is once pulled up to the ceiling in the factory, and dropped from the supply unit 170 onto the fixed tray 160 installed on the floor surface. Dropping is performed simply by dropping the starting end of the cable 100 toward the fixed tray, and there is no need for the supply unit 170 to turn or the fixed tray 160 to rotate.

  The fixed tray 160 is configured such that a winding drum 162 is provided in the vertical direction at the center of a disc-shaped bottom surface 161. Although not shown, the tray 160 also has a cylindrical outer frame in the vertical direction from the outer periphery of the bottom surface 161, and the cable 100 is wound between the winding drum 162 and the outer frame.

  The dropped cable 100 is first held at a predetermined position of the winding drum 162 on the bottom surface 161 on the bottom surface 161, and is wound around the outer periphery of the winding drum 162 in order to form a turn. This holding may be held on the fixed tray 160 with an appropriate instrument. The operator who is on the bottom surface 161 of the fixed tray performs the work of aligning and winding the dropped cable 100.

  The cable 100 is successively fed out from the supply unit 170 on the ceiling, and the next turn is formed on the outer periphery of the adjacent turn to wind the cable 100 in a spiral shape. During the winding, the cable 100 is twisted once while the cable 100 is wound around the winding drum 162. Therefore, the cable 100 in the state of being wound around the fixed tray 160 is in a state in which one twist per turn is applied to the tension material.

  Turns are formed sequentially on the outer peripheral side, and when the cable reaches the vicinity of the outer frame of the fixed tray 160 and the first layer is wound, the dropped cable is laminated on the first layer cable 100. This time, the cable 100 is similarly wound from the outer peripheral side to the inner peripheral side of the fixed tray 160. Thereafter, the winding of the cable 100 in a spiral manner and the lamination are repeated in the same manner, and the winding around the fixed tray 160 is completed. The wound cable 100 is shipped together with the fixed tray 160 and carried into the construction site.

(Handling prefabricated cable)
Next, a handling method when pulling out the cable carried into the construction site while being wound around the fixed tray will be described with reference to FIG.

  When pulling out the cable 100 wound around the fixed tray 160 at the construction site, the cable 100 is pulled out from the terminal side at the time of winding. The drawn cable 100 is pulled upward and drawn to the construction site through an appropriate guide (not shown). As a result of this pulling up, the cable 100 wound in a spiral shape is unwound and fed out, and the twist added to the tendon at that time is returned. As a result, the drawn cable 100 is returned to a state in which tendons are arranged in parallel in the sheath.

  Therefore, at the time of construction of this cable 100, each tension material can be tensioned independently and construction work can be performed.

  The prefabricated cable described above can be used in the fields of a sloping cable for a long-span bridge, a suspension cable for a suspension bridge, a prestressed cable for a prestressed concrete structure, and the like. Further, the method for handling prefabricated cables of the present invention is expected to be used in the construction field of the bridges and structures. Further, the above-described prefabricated cable manufacturing method can be used in the prefabricated cable manufacturing field.

It is sectional drawing of the prefabricated cable shown in embodiment. It is the schematic of the manufacturing line of the prefabricated cable shown to embodiment. It is explanatory drawing which shows the state at the time of winding the prefabricated cable shown to embodiment to a fixed tray. It is explanatory drawing which shows the state at the time of pulling out the prefabricated cable shown to embodiment from a fixed tray. It is explanatory drawing of the front | former stage process in the conventional prefabricated cable. It is explanatory drawing of the middle step in the conventional prefabricated cable. It is explanatory drawing of the last stage process in the conventional prefabricated cable.

Explanation of symbols

100 Prefabricated cable 10 Tensile material 20 Filler 30 Sheath
110 Supply drum 120 Aggregator 130 Filler supply
140 Extruder 150 Water-cooled tank 160 Fixed tray 161 Bottom 162 Winding drum
170 Supply section
11 Wrapped tendon 12 Sheath formed tendon
200 Supply device 210 Feeding device 220 Measuring device 230 Cutting device
240 Pipe twister 250 Eyeplate twister 260 Filler supply
270 Voice 280 Wrapping device 290 Winding drum
300 Pinch roller 310 Extruder 320 Water cooling tank 330 Pinch roller
340 Winding drum

Claims (2)

Preparing a prefabricated cable wound from one end of the cable such that substantially one twist is introduced into the cable per turn of the prefabricated cable;
And pulling the other end of the prefabricated cable upward so that the twist of the introduced prefabricated cable returns.
The prefabricated cable has a plurality of tendons and a sheath for arranging and accommodating the tendons in parallel.   2. The prefabricated cable handling method according to claim 1, wherein the tension material is any one of bare PC steel strand, plated PC steel strand, resin-coated PC steel strand, and unbonded PC steel strand.

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