JP2001200583A - Prestress introduction method for cylinder part of cylindrical concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use the minimum number of expensive anchorages and inexpensively construct a cylindrical structure by technique for introducing a peripheral prestress on the cylindrical structure 10. SOLUTION: One or a plurality of recess grooves 21 are provided on the cylinder wall face of the cylinder concrete structure 10 in parallel with a cylinder axis, a spiral PC tendon insertion duct 11 intersected with the recess grooves is formed in the wall thickness, a PC tendon 12 is inserted in the duct 11 to anchor one end, and gripped in the recess groove to be successively tightened and tighten an entire length so as to be finally anchored on the other end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for introducing circumferential prestress into a cylindrical body of a cylindrical container structure such as a tank or a silo, or a cylindrical concrete structure such as a chimney or a pressure pipe.

[0002]

2. Description of the Related Art Conventionally, a cylindrical container structure such as a tank 40 for storing a fluid as illustrated in FIG. 8, a surge tank of a pumped storage power plant, and a cylindrical concrete structure such as a cement silo ensure hermeticity. In addition, a container structure having a PC structure in which a prestress is introduced into a wall is used to counter hoop tension caused by the internal pressure of the stored material.
In the case where circumferential prestress is introduced into the wall, as shown in an example in FIG. 9, a plurality of (in this example, four places) are provided on the outer surface of the wall 41.
Is formed on the pilaster 45 in the circumferential direction PC.
Generally, the tendon 12 is fixed. FIG. 9 is a perspective view of the tubular body, in which semi-circular circumferential PC tendons are provided independently over the entire length of the prestress introduction area. FIG. 10 shows a cross section taken along line DD in FIG. PC
The tension members 12 are provided in a number of stages, and each stage uses one PC tension member 12 for each semicircle, and crosses at 180 degrees different positions with the pilaster 45 to tension the PC tension members 12 at both ends. And fix it. In the next stage, the fixing position is set to a position different by 90 degrees, and similarly, the two PC tendon members 12 are crossed by the pilaster 45 at 180 degrees, and are fixed at both ends of the PC tendon material 12 and fixed. The above process is repeated alternately at each stage in the axial direction to introduce a circumferential prestress into the cylindrical container wall.
In such a conventional technique, a large amount of the PC tendon 12 is required because the prestress introduction efficiency is reduced due to friction between the PC tendon 12 and the insertion duct.
This causes problems such as the necessity of reinforcement due to the concentration of stress and the necessity of a large number of expensive fixing devices, which causes a rise in construction costs.

On the other hand, the present applicant has disclosed in Japanese Patent Laid-Open No. 9-31918.
In the publication, a tension fixing method of a PC tendon material which can be fixed by using a minimum number of fixing tools is disclosed. The technique is a technique for reinforcing a columnar structure, and a mortar around the columnar structure. A curved panel is attached with a slit for tension, a PC tension member is spirally inserted into the curved panel plate, and one end of the tension member is locked at the lower or upper part of the curved panel, and tension is applied from the locking point. A jack is inserted into the tension slit between the curved panels toward the other end of the tension member to tension the PC tendon exposed at the slit, and the jack is sequentially tensioned while moving the jack toward the other end of the tension member. This is the technology that establishes. This technique is a technique for reinforcing a columnar structure by introducing a tightening force to the outer periphery of the columnar structure serving as a core.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a technique for introducing a circumferential prestress into a cylindrical structure. The purpose is to provide. In this case, the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 9-31918 can minimize the number of fixing devices to be used and can surely fix the tension. Although the above-mentioned technology is to tighten and reinforce the structure serving as the core, the present invention is completely different from this, in which a prestress is introduced in the circumferential direction of the wall of the cylindrical structure. The present invention has created a technically superior prestress introduction technology for a cylindrical structure capable of reducing costs such as improvement of introduction efficiency, elimination of stress concentration, and reduction of expensive fixing tools.

[0005]

According to the present invention, a spiral PC tendon insertion duct is formed within a wall thickness of a cylindrical body of a cylindrical concrete structure, and a number of intermediate tension portions are provided in the middle of the duct. A cylindrical concrete member, wherein a PC tendon is inserted into a duct and one end is locked, the PC tendon is sequentially tensioned at an intermediate tension portion to tension the entire length, and finally fixed at the other end. This is a method for introducing prestress into the cylindrical body of the structure.

According to the present invention, a spiral continuous over the entire length of a prestress introduction area is provided on a cylinder wall of a prestress introduction area against a hoop tension acting on a cylinder of a cylindrical concrete structure such as a tank for storing a fluid. This is a technique for efficiently introducing circumferential prestress by a minimum number of fixing parts using a single PC tendon material. The spiral PC tendon insertion duct has a number of intermediate tension portions in the middle thereof. The middle tension part is pulled by holding the PC tendon material with a jack.
A portion where the PC tendon is exposed so that tension can be introduced into the C tendon, and a supporting portion that supports the reaction force of the jack is provided. For example, a concave portion or a hole provided in a concrete wall. As the intermediate tension portion, a concave groove parallel to the cylinder axis is provided on the inner surface or the outer surface of the cylindrical wall, and a PC tendon insertion duct is opened in the concave groove so that the PC tendon is exposed in the concave groove. If it is set, it can be easily formed.

In addition, a plurality of the cylindrical concrete structures are erected so as to circumscribe each other, and a spiral PC tendon insertion duct is communicated with a duct in an adjacent cylinder wall at a portion circumscribing each cylinder. It is preferable that the PC tendon is inserted through the duct of the cylindrical body in order to simultaneously introduce prestress into a plurality of cylindrical concrete structures. This cylindrical concrete structure is composed of a plurality of circumscribed cylinders, and the PC tendon insertion duct is connected from one cylinder to the other cylinder across the circumscribed portion. For example, when two cylindrical concrete structures are connected, a PC tendon insertion hole is formed in a shape that is generated when the figure eight is plane and the two are overlapped with one stroke. Three or more cylindrical structures may be connected.

Further, in order to preferably carry out the present invention, using a portable pinch roller for inserting a PC strand disclosed in Japanese Unexamined Patent Application Publication No. 9-37953, which has been separately proposed by the present applicant, makes it possible to continuously spiral the tension member of the PC. It is easy to insert into the duct.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view illustrating an example of a cylindrical portion of a container structure according to an embodiment. This figure shows a state in which PC strands 12 that are continuous over the entire length of the cylindrical body are disposed in a spirally formed PC tendon insertion hole (sheath) 11. The PC tendon insertion holes 11 are exposed in concave grooves 21 provided at four circumferential positions in parallel with the cylinder axis. This exposed part is an intermediate tension part. FIG. 2 is a cross-sectional view taken along the line AA of FIG.
It shows that it is exposed inside.

FIG. 3 is a diagram for explaining the introduction of prestress.
In FIG. 3, for ease of explanation, the tension jacks 31 to 3 are used.
The groove 21 into which the groove 4 is inserted is drawn in the same groove. However, in the embodiment, the groove 21 is located in a groove which is shifted by 1/4 turn or 1/2 turn. This position should be determined to be the most effective position for introducing prestress while taking into consideration the friction between the insertion duct and the PC strand.

One end of the PC strand 12 is connected to the terminal fixing body 1
The first jack 31 is attached to the PC strand 12 which is tightly locked at 3 and is exposed in the recess 21 at a position half a circumference apart, and operates the first jack 31 to introduce a tension. Next, the second jack 32 is attached to the PC strand 12 exposed in the concave portion 21 at a position further half-circumferentially from the first jack 31, and the second jack 32 is held in a state where the tension of the first jack 31 is maintained. Activate the jack 32 to introduce tension. Thereafter, while maintaining the tension of the second jack 32, the tension of the first jack 31 is released, and the first jack 31 is moved to the next jack mounting position. The jack after the movement is 33. Jack 33
The second jack 32 is released and moved to the position of the jack 34 in a state where the tension is introduced and held by operating the. In this way, the movement and the remounting are alternately repeated to the other end of the PC strand to introduce a prestress. The arrow 35 indicates the direction of introduction of the prestress, but the same applies to the introduction from the top to the bottom.

Further, the number of turns becomes large, and the supplied P
If the length of the C-strand is insufficient, the other end may be fixed at an intermediate position of the spiral and the PC strands may be connected to each other, or one end of the PC strand may be further started from that position.

FIG. 4 is a front view of the tension jack 31 mounted in the tension slit of the wall. The tension jack 31 is provided on the PC strand 12 exposed in the groove 21.
Since it is mounted so as to cover from the outside of 1, it is easy to attach and detach.

FIG. 5 is a side view showing the concave groove 21 and the tension jack 31 mounted in the concave groove 21 as viewed in the direction of arrows BB in FIG. The PC strand 12 is inserted into a duct formed by the sheath 11 in the wall, and the PC strand 1
2 is exposed in the concave groove 21 and is grasped and tensioned by the wedge of the tension jack 31. The reaction force of the tension jack 31 is supported by the inner surface of the groove 21. After the prestress of the wall is introduced, grout is applied to the sheath 11 and the concave groove 21 is filled with concrete.

FIG. 6 shows another embodiment in which two cylindrical concrete structures 10a and 10b are circumscribed to form an integral structure, and a PC strand inserted from one cylindrical concrete structure 10a. 12 are continuously inserted through the other cylindrical concrete structure 10b. FIG. 6 is a perspective view, and FIG. 7 is a view taken in the direction of arrows CC in FIG. The PC tendon 12 is continuously inserted through the two cylindrical concrete structures 10a and 10b so as to write the Arabic numeral 8 in one stroke.

FIG. 11 is a plan view showing an example of the tension jack 31 optimal for introducing prestress according to the present invention. The jack 31 has a short length that can be installed in the groove, and the wedge 37 is moved in conjunction with the two cylinders 35 and the ram 36 so that the PC strand 12 can be held in the middle of the PC strand 12.
Tension. 12 and 13 are respectively a view as seen from arrows EE and FF in FIG.

In the above embodiment, an example was described in which four concave grooves 21 were provided on the outer wall surface of a cylindrical concrete structure. However, the present invention is not limited to this. effective. Also, the number and arrangement of the grooves 21 can be appropriately designed in consideration of, for example, the friction between the PC strand and the duct of the cylindrical concrete structure and the effectiveness of introducing prestress.

[0018]

According to the method of the present invention, a continuous helical PC tendon is inserted into the wall of a cylindrical concrete structure over the entire length of the prestress introduction area, and the PC tendon is jacked along the way. And tensioning sequentially, eliminating the need to provide a fixing section such as a pilaster, so that the entire length of the PC tensioning material wound spirally can be tensioned.
Only one fixing body is required. Therefore, it is possible to reduce the number of the PC tendon and the fixing device which have conventionally contributed to the soaring construction cost, and it is not necessary to reinforce the fixing portion, and it is possible to easily apply the predetermined tension. And the effect is enormous.

Further, when the cylindrical concrete structure is composed of a plurality of cylinders circumscribing, the PC tendon insertion duct may be continuously arranged from one cylinder to the other cylinder and tensioned. Further, the effect of reducing the number of fixing members is great.

[Brief description of the drawings]

FIG. 1 is a perspective view of a cylindrical structure according to an embodiment.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory view showing the steps of the method of the present invention.

FIG. 4 is a front view of a jack in an intermediate tension portion.

FIG. 5 is a view taken in the direction of arrows BB in FIG. 4;

FIG. 6 is a perspective view of another embodiment.

FIG. 7 is a sectional view taken along the line CC of FIG. 6;

FIG. 8 is a partially sectional side view showing an example of a cylindrical container structure.

FIG. 9 is a perspective view illustrating a conventional technique.

FIG. 10 is a sectional view taken along the line DD in FIG. 9;

FIG. 11 is a plan view of a jack used in the present invention.

FIG. 12 is a view as seen in the direction of arrows EE in FIG. 11;

FIG. 13 is a view as seen from the direction of arrows FF in FIG. 11;

[Explanation of symbols]

 10a, 10b Cylindrical concrete structure 11 Sheath (tensioner insertion hole) 12 PC strand (PC tensioner) 13 Terminal fixing body 21 Groove 31, 32, 33, 34 Tensioning jack 35 Arrow 35 Cylinder 36 Ram 37 Wedge

Claims (3)

[Claims] 1. A spiral PC tendon insertion duct is formed within the wall thickness of a cylindrical body of a cylindrical concrete structure, and a number of intermediate tension portions are provided in the middle of the duct.
A tubular member of a cylindrical concrete structure, wherein a tension member is inserted and one end is locked, the PC tension member is sequentially tensioned at the intermediate tension portion to tension the entire length, and the other end is finally fixed. Prestress introduction method of the department. 2. The cylindrical concrete according to claim 1, wherein the intermediate tension portion is formed of one or more grooves provided on a cylindrical wall surface of the cylindrical concrete structure in parallel with a cylindrical axis. A method for introducing prestress into the cylinder of a structure. 3. A plurality of cylindrical concrete structures are erected so as to circumscribe each other, and a spiral PC tendon insertion duct is communicated with a duct in an adjacent cylinder wall at a portion circumscribing each cylinder. 3. The method for introducing prestress into a cylindrical portion of a cylindrical concrete structure according to claim 1, wherein the PC tendon is inserted through the duct of the cylindrical body in order.