JP2017166258A - Primary cable mantle pipe in suspension floor slab bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive primary cable mantle pipe being high in a degree of freedom of a shape.SOLUTION: This primary cable mantle pipe comprises a primary cable insertion space of a rectangle when viewed in the pipe axis direction for solving its problem, and a height dimension up to a ceiling surface from the pipe axis of the primary cable insertion space is continuously increased toward an opening by taking into consideration a change in a sag quantity of a primary cable caused by progress of construction of a bridge body in a range up to a bridge body side opening from a predetermined intermediate position on the pipe axis. Due to being manufacturable by using a flat steel plate, a height dimension up to the ceiling surface from the pipe axis of the primary cable insertion space of the range up to the bridge body side opening from a predetermined position on the pipe axis, can be determined in a high degree of freedom, and cost can be reduced more than the mantle pipe which processes a steel pipe.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a primary cable mantle used in an anchorage fixing part of a primary cable in construction of a bridge by a suspended floor slab construction method.

  There is a suspension floor erection method as a construction method of the bridge. In the suspended floor slab construction method, a plurality of primary cables are stretched parallel to each other with a downward sag between the abutments, and a precast concrete suspended floor slab is erected on these primary cables. . For example, in the case of an upper-floor type suspended floor slab bridge, an upper floor slab is installed on the lower floor slab installed on the primary cable via a spandrel part of diagonal or vertical material, and the upper floor slab is placed on the upper floor slab. The bridge body is completed by constructing the road surface. Depending on the structure of the bridge, a secondary cable may be provided separately from the abutment on the lower floor slab, or a floor slab cable may be separately provided on the upper floor slab.

  In order to bridge the primary cable that receives the load of such a bridge body between the abutments, both ends of the primary cable need to be fixed with high strength to the abutment of the reinforced concrete structure that is cast in the field. The following are known as the fixing structure of the primary cable. As the primary cable, a cable in which a steel tubular fixing body called a condominium is crimped on the outer periphery of the end portion is used. The end including the fixing part of the primary cable is inserted into the sheath embedded in the abutment from the bridge body side, and the nut is screwed onto the end of the primary cable protruding from the end face of the abutment with a washer plate, and tightened. The primary cable end is fastened to the abutment (see Patent Document 1).

JP-A-2005-282131

  In the suspended floor slab erection method, as the construction of the bridge body progresses, the load received by the primary cable increases and the sag amount of the primary cable increases. When the amount of sag increases, the primary cable other than the fixing part in the outer tube such as the sheath is also displaced, so that the surface of the protective coating of the primary cable and the edge of the opening end of the outer tube on the bridge body point contact each other. A local stress is generated in the cable, and the surface of the protective coating of the primary cable may be damaged, or the primary cable body may be damaged.

  In order to deal with such problems, the inner diameter in the range from the opening on the bridge body side to a certain distance in the tube axis direction is set to the opening on the bridge body side, such as Diaboro pipe, trumpet pipe, and bellmouth processed bent steel pipe. A mantle tube having a shape that expands as it approaches may be employed.

  However, in the diameter expansion process of the steel pipe, the wall thickness decreases as the diameter increases. For this reason, when trying to obtain an outer tube with a diameter-expanded portion that matches the displacement of the primary cable in the sheath as the bridge construction progresses by expanding the diameter from the steel pipe, a steel pipe with a larger wall thickness is required. There were problems such as difficulty in processing and increased costs.

  In view of the circumstances as described above, the object of the present invention is to provide a high degree of freedom in the primary cable insertion space that can avoid contact with the primary cable with respect to an increase in the sag amount of the primary cable accompanying the progress of construction of the bridge body. It is to provide a primary cable mantle that can be obtained by

  In order to achieve the above object, a primary cable mantle according to an embodiment of the present invention includes a condominium provided at one end of a primary cable stretched between two abutments in a suspended floor laying method. A primary cable mantle tube that is disposed on the one abutment and into which the one end of the primary cable is inserted, and has a rectangular primary cable insertion space when viewed in the tube axis direction. At least in the range from the predetermined position on the tube axis to the opening on the bridge body side, the height dimension from the tube axis to the ceiling surface of the primary cable insertion space is continuously increased as the opening approaches. It is formed to be large.

  According to the present invention, considering the change in the sag amount of the primary cable accompanying the progress of construction of the bridge body, from the pipe axis of the primary cable insertion space in the range from the predetermined position on the pipe axis to the opening on the bridge body side. By determining the height to the ceiling surface, the primary cable insertion space that can avoid contact with the primary cable can be obtained with a high degree of freedom against the increase in the sag amount of the primary cable as the bridge construction progresses. be able to.

  Further, in the primary cable mantle of the present invention, the rectangular primary cable insertion space can be formed with high accuracy by an inexpensive processing method using a flat steel plate, and the cost is lower than that of the mantle tube processed from the steel pipe. Can be lowered.

It is a side view which shows the state at the time of tensioning of the primary cable 1 in the construction of the bridge by a suspended floor slab construction method. FIG. 2 is a cross-sectional view showing a state before the end portion of the primary cable 1 is inserted into the primary cable mantle tube 10 in the fixing structure of the primary cable 1 using the primary cable mantle tube 10 according to the embodiment of the present invention. It is sectional drawing which shows the state immediately after tension | tensile_strength of the primary cable 1 in the fixing structure of the primary cable 1 using the primary cable mantle tube 10 of one Embodiment which concerns on this invention. 1 is a side view of a primary cable mantle tube 10 according to an embodiment of the present invention viewed from a horizontal direction orthogonal to the direction of a tube axis 30 and a side view viewed from both sides of the tube axis 30 direction. It is a side view which shows the tension | tensile_strength state of the primary cable 1 at the time of completion of the bridge body C in the construction of the bridge by a suspended floor slab construction method. It is sectional drawing which shows each state of the primary cable 1 in the primary cable mantle tube 10 at the time of primary cable extension time and the bridge body C completion time.

Hereinafter, a primary cable mantle according to an embodiment of the present invention will be described with reference to the drawings.
First, the application of the primary cable mantle tube of this embodiment will be described.

FIG. 1 is a side view showing a state in which a primary cable 1 is stretched between abutments A and B in the construction of a bridge by a suspended floor slab construction method.
A plurality of primary cables 1 are stretched between the abutments A and B. After the lower chord material, diagonal material / vertical material, and upper chord material are erected on these primary cables 1, interstitial concrete is laid between the lower chord material and between the upper chord materials, and concrete is cast on both sides in the bridge axis direction. A road surface construction or the like is performed to complete the bridge body C as shown in FIG.

  2 and 3 are sectional views showing a fixing structure of the primary cable 1 using the primary cable mantle tube 10 according to the embodiment of the present invention. 2 and 3, the fixing structure of the primary cable 1 in the abutment B of FIG. 1 is shown, but the fixing structure of the primary cable 1 in the abutment A is also the same.

A primary cable mantle tube 10 for inserting the primary cable 1 is embedded in the abutment B having a reinforced concrete structure.
As the primary cable 1, for example, a PC steel wire 1a whose surface is covered with a protective coating 1b made of polyethylene resin for rust prevention, for example, is used. An end portion of the primary cable 1 is provided with a condominium 2 obtained by inserting the end portion of a PC steel strand 1a into a thick cylindrical tube (sleeve) made of steel and crimping it. A thread 2 a is provided on the peripheral surface of the apartment 2.

  The primary cable 1 is inserted from the opening 10a on the bridge body C side of the primary cable mantle tube 10 embedded in the concrete of the abutment B, and is arranged so that the tip portion of the apartment 2 protrudes from the opening 10b on the opposite side. The end of the primary cable 1 is fastened to the abutment B by screwing the nut 20 into the tip of the apartment 2 protruding from the opening 10b of the primary cable mantle 10 and tightening.

Next, the configuration of the primary cable mantle tube 10 will be described.
FIG. 4 is a side view of the primary cable mantle tube 10 viewed from the horizontal direction perpendicular to the direction of the tube axis 30 and a side view viewed from both sides of the tube axis 30 direction.

  The primary cable mantle tube 10 is provided with a rectangular cable insertion space 11 when viewed in the direction of the tube axis 30. The opening 10a on the bridge body C side in the direction of the tube axis 30 of the primary cable mantle tube 10 is hereinafter referred to as "first opening 10a", and the opening 10b on the opposite side to the bridge body C side is hereinafter referred to as "second opening 10b". Call it.

  In the cable insertion space 11 of the primary cable mantle tube 10, the height dimension from the tube axis 30 of the primary cable insertion space 11 to the ceiling surface in the range 12 from a predetermined position in the direction of the tube axis 30 to the first opening 10 a (pipe The height in the direction orthogonal to the axis 30 is continuously increased toward the first opening 10a in consideration of the displacement of the deflection of the primary cable 1 accompanying the progress of the construction of the bridge body C. Is set. That is, the cable insertion space 11 in the primary cable mantle 10 includes a constant height portion 14 in which the height of the rectangular cable insertion space 11 is constant, and the height of the rectangular cable insertion space 11 as it approaches the first opening 10a. It is comprised with the height change part 15 which becomes large continuously.

  The primary cable mantle 10 is manufactured, for example, by joining four flat steel plates 101, 102, 103, 104 having a thickness of 4.5 mm to 6.0 mm by welding or the like. In this case, each of the four flat steel plates 101, 102, 103, 104 becomes a ceiling surface, a bottom surface, and two side wall surfaces that form the cable insertion space 11. Are joined. Here, the flat steel plate 101 forming the ceiling surface of the cable insertion space 11 is obtained by bending a portion corresponding to the height changing portion 15 after cutting the flat steel plate material. Since both the bottom surface of the cable insertion space 11 and the two side wall surfaces may be flat surfaces, the flat steel plates 102, 103, and 104 may be obtained only by cutting from a flat steel plate material.

  In addition, each surface except the ceiling surface that forms the cable insertion space 11 in the primary cable mantle tube 10 and the ceiling surface that forms the cable insertion space 11 of the constant height portion 14 are parallel to the direction of the tube axis 30. It is a surface.

  A bearing plate 16 is provided at the second end portion of the primary cable mantle tube 10. The support plate 16 includes four flat steel plates 101 that form a cable insertion space 11 by welding or the like so as to protrude from the outer peripheral surface of the primary cable mantle tube 10 in a direction perpendicular to the tube axis 30 of the primary cable mantle tube 10. , 102, 103, 104. In the present embodiment, for example, a rectangular bearing plate 16 having a thickness of 65 mm and a vertical and horizontal size of 400 mm is used. The pressure bearing plate 16 is provided with a circular condominium insertion hole as the second opening 10 b in the primary cable mantle tube 10.

  Both end surfaces 16 a and 16 b of the bearing plate 16 in the direction of the tube axis 30 are surfaces orthogonal to the tube axis 30. In the fixed state of the primary cable 1, the end face 16 a on the bridge body C side of the bearing plate 16 abuts on the end face B 1 of the abutment B, so that one end of the primary cable 1 is supported by the abutment B.

  In this embodiment, the bearing plate 16 is integrated with the primary cable mantle tube 10 in advance by welding or the like as described above. However, the tubular body portion of the primary cable mantle tube 16 and the bearing plate 16 are connected to each other. When the separated cable is carried into the site, only the tube portion of the primary cable mantle tube 16 is embedded in the abutment concrete, and the condominium 2 of the primary cable 1 is fastened to the abutment B with the nut 20, the bearing plate 16 May be sandwiched between the opening end face of the tube portion of the primary cable mantle tube 16 and the nut 20.

  FIG. 5 is a side view showing a stretched state of the primary cable 1 when the bridge body C is completed. Here, the primary cable 1 receives the load of the bridge body C and bends larger than the tension point. That is, the sag amount of the primary cable 1 at the time of completion of the bridge body C is larger than the sag amount of the primary cable 1 immediately after the tension shown by the dotted line in the figure due to an increase in the load of the bridge body C as the construction progresses. It grows as shown by the solid line.

  The height dimension (the height in the direction perpendicular to the tube axis 30) of the cable insertion space 11 from the tube axis 30 to the ceiling surface in the height changing portion 15 of the primary cable mantle tube 10 of this embodiment is as described above. In consideration of the increase in the sag increase of the primary cable 1 accompanying the progress of the construction of the bridge C, the height dimension is set so as to increase continuously as it approaches the first opening 10a.

FIG. 6 is a cross-sectional view showing the respective states of the primary cable 1 in the primary cable mantle tube 10 immediately after the primary cable is stretched and when the bridge body C is completed.
In the figure, the dotted line indicates the state of the primary cable 1 immediately after the extension, and the solid line indicates the state of the primary cable 1 when the bridge body C is completed.

  Thus, in the primary cable mantle tube 10 of the present embodiment, the primary cable 1 is within the cable insertion space 11 of the height changing portion 15 due to the increase of the sag in the cable insertion space 11 of the height changing portion 15. Although displaced downward, the height dimension from the tube axis 30 to the ceiling surface of the cable insertion space 11 in the height changing portion 15 (height in the direction orthogonal to the tube axis 30) is the progress of construction of the bridge body C. In consideration of the increase in the sag increase of the primary cable 1 due to the height, the height dimension is set so as to increase continuously as it approaches the first opening 10a. The primary cable 1 reaches the bottom surface of the cable insertion space 11 of the height changing portion 15 when the bridge body C is completed by setting so as to pass a position close to the ceiling surface of the cable insertion space 11 of the portion 15. No.

  As described above, by using the primary cable mantle tube 10 of this embodiment, contact between the surface of the protective coating 1b of the primary cable 1 and the inner surface of the primary cable mantle tube 10 and the edge of the first opening 10a is avoided. It is possible to prevent damage to the surface of the protective coating 1b of the primary cable 1 as well as damage to the main body of the primary cable 1 (PC steel stranded wire 1a).

  Moreover, since the primary cable jacket 10 of this embodiment can be manufactured using a flat steel plate, the cable insertion space 11 of the height changing portion 15 can be easily formed with a high degree of freedom. For this reason, considering the change in the sag amount of the primary cable 1 with the progress of the construction of the bridge body C, the cable insertion space 11 whose height dimension continuously increases as it approaches the first opening 10a is easily formed. Therefore, the cost can be reduced as compared with a mantle tube processed from a steel pipe.

  The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the technical idea of the present invention.

A, B ... abutment C ... bridge body 1 ... primary cable 10 ... primary cable mantle 10a ... first opening 11 ... primary cable insertion space 30 ... tube shaft 101, 102, 103, 104 ... flat steel plate

Claims (2)

In order to fix a condominium provided at one end of a primary cable stretched between two abutments in the suspended floor slab construction method to one of the abutments, the one of the abutments is disposed on the abutment. A primary cable jacket through which one end is inserted,
A rectangular primary cable insertion space when viewed in the tube axis direction, and at least in a range from a predetermined position on the tube axis to the opening on the bridge body side, from the tube axis to the ceiling surface of the primary cable insertion space A primary cable mantle tube formed so that the height dimension of the cable continuously increases as the height approaches the opening. The primary cable mantle according to claim 1,
A primary cable mantle tube in which the primary cable insertion space is formed using a flat steel plate.

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