JP5261418B2 - Method for manufacturing prestressed concrete member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a prestressed concrete member, which makes it unnecessary for an anchoring fitting to be left behind at the end of the concrete member, and which enables prestress to be easily introduced even on a construction site etc. with a limited working space. <P>SOLUTION: This method for manufacturing the prestressed concrete member includes: a tensioning step of inserting a tendon 4 through an insertion hole 3 formed in the concrete member 2 and bearing plates 6 disposed on both the end surfaces of the concrete member 2, and of introducing a tensioning force into the tendon 4; a compression step of introducing the prestress into the concrete member 2 via the bearing plates 6 and 6 by releasing the tensioning force of the tendon 4; a filling step of infilling a filler 5 into the insertion hole 3; and an anchoring step of reintroducing the tensioning force into the tendon 4 after the expression of the strength of the filler 5, and of anchoring the tendon 4 by releasing the reintroduced tensioning force, so as to remove the bearing plate 6. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a prestressed concrete member.

  Prestressed concrete members include those manufactured by the pre-tension method and those manufactured by the post-tension method (see Patent Document 1 and Patent Document 2).

In the pre-tension method, in a production yard or the like in a factory or a construction site, the tension is introduced to the concrete member 101 by placing concrete with the tension applied to the tension material 102 (FIG. 5). reference).
When the pre-tension method is adopted, the pre-stressed concrete member into which the tension force is introduced is transported to the site and then arranged at a predetermined position.

On the other hand, the post-tension method mainly introduces prestress into the concrete member at the site.
In the post-tension method, prestress is introduced through a fixing hardware embedded in the end of the concrete member in advance.

JP 2009-155878 A JP 2000-230273 A

When the pre-tension method is adopted, the transportation cost increases when the precast factory is far from the construction site, which may affect the construction cost of the entire construction.
Further, since it is necessary to arrange a large-scale device having a reaction abutment, a self-balancing steel frame 103 (see FIG. 5), etc., it has been difficult to employ at a construction site.

  When the post-tension method is adopted, prestress can be introduced relatively easily even at the construction site, but fixing hardware (fixed hardware such as bearing plates and nuts) is embedded at the end of the concrete member. Therefore, there is a possibility that restrictions may be imposed on the bonding and cross-sectional dimensions of the concrete member.

  The present invention is a method for producing a prestressed concrete member that does not require the fixing hardware to be left at the end of the concrete member and can easily introduce prestress even in a construction site where the work space is limited. It is an issue to provide.

  In the manufacturing method of the prestressed concrete member of the present invention that solves such a problem, the tension material is applied to the insertion holes formed in the concrete member and the bearing plates (removed later) disposed on both end faces of the concrete member. A tensioning step for inserting a tension force into the tension member while inserting, a compression step for introducing a prestress to the concrete member via the support plate by releasing the tension force of the tension member, and in the insertion hole After the filling material is filled with the filler, and after the strength of the filler material is expressed, the tension material is reintroduced into the tension material to release the tension force of the jack, and the tension material is attached by the adhesive force between the tension material and the filler material. Fixing the concrete member (introducing prestress into the concrete member by the adhesive force) and removing the bearing plate. To have.

  This prestressed concrete member manufacturing method makes it possible to manufacture prestressed concrete members without requiring a large pretensioning device, so that prestressing can be easily introduced even in construction sites where work space is limited. can do.

  Further, since prestress is introduced through the adhesive force of the filler, there is no need to embed a fixing metal in the concrete member. Therefore, the degree of freedom in designing the joint structure and cross-sectional dimensions of the concrete members is increased.

  The fixing step of the manufacturing method of the prestressed concrete member is a first fixing operation in which the tension plate is reintroduced from one end and then the supporting plate disposed on the one end side is removed while releasing the tension force. And a second fixing operation of removing the support plate disposed on the other end side while releasing the tension force after reintroducing the tension force from the other end to the tension material.

Thereby, it becomes possible to divert one jack, and it becomes possible to reduce manufacturing cost.
Further, since hardware such as a bearing plate can be reused for manufacturing other prestressed concrete members, it is possible to reduce material costs.

  According to the method for producing a prestressed concrete member of the present invention, it is not necessary to leave a fixing hardware at the end of the member, and it is possible to produce a prestressed concrete member without requiring a large-scale prestress introduction device. It becomes possible.

(A) is sectional drawing which shows the prestressed concrete member based on this Embodiment, (b) is the same stress distribution map (at the time of completion of a fixing process: member completion). (A) is sectional drawing which shows the manufacturing method of the prestressed concrete member shown in FIG. 1, (b) is the stress distribution map (compression process). (A) is sectional drawing which shows the manufacturing method of the prestressed concrete member following FIG. 2 (a), (b) is the same stress distribution map (fixing process of one end). (A) is sectional drawing which shows the manufacturing method of the prestressed concrete member following Fig.3 (a), (b) is the same stress distribution diagram (fixing process of the other end). It is sectional drawing which shows an example of the manufacturing method of the conventional prestressed concrete member.

This embodiment demonstrates the case where a prestressed concrete beam is manufactured with the manufacturing method of the prestressed concrete member which concerns on this invention.
In addition, the member manufactured by the manufacturing method of the prestressed concrete member of this invention is not limited to a beam.

  As shown in FIG. 1A, a prestressed concrete beam (hereinafter simply referred to as “PCa beam”) 1 of the present embodiment includes a beam body 2, a sheath tube 3, a tension member 4, a filler 5, and It is configured with.

The beam body 2 is a member made of reinforced concrete, and a tension member 4 is disposed along the longitudinal direction on the lower side of the cross section.
As shown in FIG. 1B, prestress is introduced into the beam main body 2 via the tension material 4, but the cross-sectional shape and various dimensions are not limited and can be set as appropriate.

The sheath tube 3 is a tube material embedded along the longitudinal direction of the beam body 2 on the lower side of the cross section of the beam body 2.
Both ends of the sheath tube 3 are opened facing both end surfaces of the beam body 2. The sheath tube 3 forms an insertion hole in the beam body 2. A tension material 4 is inserted into the sheath tube 3, and a gap around the tension material 4 is filled with a filler 5.

The outer surface of the sheath tube 3 is in close contact with the beam body 2 and is integrated with the tension material 4 via the filler 5.
In this embodiment, a spiral sheath tube is used as the sheath tube 3, but the present invention is not limited to this. Further, the tube material forming the insertion hole is not limited to the sheath tube. Moreover, if it is possible to form the insertion hole, it is not always necessary to dispose the pipe material.

The tendon 4 is a member for introducing prestress into the beam main body 2, and is inserted through the sheath tube 3 below the cross section of the beam main body 2.
In this embodiment, a high-strength reinforcing bar is used as the tendon 4, but the material constituting the tendon is not limited. For example, a PC steel bar or a PC steel wire may be used.

As shown in FIG. 1A, the tendon material 4 is fixed to the beam main body 2 via a filler 5 filled in the sheath tube 3.
As shown in FIG. 1B, the prestress P introduced into the PCa beam 1 gradually increases at the fixing portions Pa and Pa formed at both ends of the PCa beam 1, and is substantially constant at portions other than the fixing portions at both ends. It becomes.

The filler 5 is filled in the gap between the sheath tube 3 and the tension material 4. When the filler 5 is solidified, the tendon 4 is fixed in the sheath tube 3.
In this embodiment, grout (mortar) is used as the filler 5, but the material constituting the filler 5 only needs to have a strength to solidify and join the sheath tube 3 and the tension material 4. As a result, a prestressed concrete member is formed in which the tension of the tension material is introduced into the concrete of the main body via the grout and the sheath tube by the adhesion force.

  The PCa beam manufacturing method includes a beam body manufacturing process, a tensioning process, a compression process, a filling process, and a fixing process.

The beam body manufacturing process is a process of constructing the beam body 2 in which the sheath tube 3 is embedded.
The beam body 2 is constructed by placing concrete in a mold (not shown) in which the sheath tube 3 is disposed.

Next, the tendon 4 is inserted into the sheath tube 3. Both ends of the tendon 4 are projected from the sheath tube 3.
The tendon material 4 may be inserted into the sheath tube 3 before placing the concrete. That is, the sheath tube 3 into which the tension material 4 is inserted in advance may be disposed in the mold, or after the tension material 4 is inserted into the sheath tube 3 installed in the mold, the concrete is placed. Also good.

  The tensioning process is a process of introducing a tension force to the tension material 4.

  Prior to the introduction of the tension force to the tension member 4, first, the support plates 6 are disposed on both end faces of the beam body 2. Both ends of the tension material 4 are inserted through the support plate 6 and protrude outward. The bearing plate 6 is fixed to the end surface of the beam body 2 by using a nut 6 a screwed to the tension member 4.

As shown in FIG. 2A, the tension force is introduced into the tension material 4 by a pre-stress introduction jack (hereinafter simply referred to as “jack 7”) installed at one end of the tension material 4.
A jack chair 8 is interposed between the jack 7 and one of the pressure bearing plates 6, and the jack 7 and the tension material are connected via a coupler 9.
The jack reaction force is applied to the beam body 2 via the jack chair 8 and the bearing plate 6.

  When a predetermined tension force is introduced into the tension member 4 by the jack 7, the nut 6 a is tightened and brought into close contact with the bearing plate 6. Thereafter, the load by the jack 7 is gradually reduced and the coupler 9 is removed (compression process).

  By gradually loading the jack load, a compressive force is introduced into the beam body 2 via the bearing plate 6. Therefore, as shown in FIG.2 (b), a fixed prestress is introduced into the beam main body 2 over the full length (compression process).

The filling step is a step of filling the filler 5 in the gap between the sheath tube 3 and the tension material 4 (see FIG. 3A).
Although the filling method of the filler 5 is not limited, for example, it is performed by press-fitting the filler 5 from an injection hole (not shown) formed in the bearing plate 6 in advance. At this time, an exhaust hole (not shown) is formed in the pressure bearing plate 6, and the air in the sheath tube 3 is discharged with the press-fitting of the filler 5 so that the air does not stay in the sheath tube 3. To.

The fixing process is a process in which after the strength of the filler 5 is expressed, the tension force is reintroduced into the tension material 4 and the supporting plates 6 and 6 are removed.
The fixing process is divided into two operations.

  In the first operation, first, as shown in FIG. 3A, the tension force is reintroduced into the tension member 4 by the jack 7 connected to one end of the tension member 4. Although the reintroduction tension is not limited, it is approximately the same as the initial tension (tension during the tension process). At this time, a tension force P ′ (broken line portion in FIG. 3B) continuous to the jack 7 is introduced into the tension member 4.

  When the tension force is reintroduced to the tension member 4, the nut 6 a that fixes the bearing plate 6 disposed on one end side is moved to the jack 7 side.

Next, the jack load is gradually reduced until it becomes zero.
When the jack load becomes zero, fixing (replacement) of the tendon material 4 is completed, and the tension force of the tendon material 4 is transmitted to the beam body 2 by the adhesive force with the filler 5. As a result, as shown in FIG. 3B, the fixing portion Pa is formed only at one end of the beam main body 2.

  The jack 7, jack chair 8, and coupler 9 are removed from one end side of the tension material 4 and installed on the other end side of the tension material 4.

Continue the second work.
In the second operation, first, as shown in FIG. 4A, the tension force is reintroduced into the tension member 4 by the jack 7 installed at the other end of the tension member 4. Although the reintroduction tension is not limited, it is approximately the same as the initial tension (tension during the tension process). At this time, a tension force P ′ (broken line portion in FIG. 4B) continuous to the jack 7 is introduced into the tension material 4.

  Next, the nut 6a that fixes the bearing plate 6 disposed on the other end side is moved to the jack 7 side.

Subsequently, the jack load is gradually reduced until it becomes zero.
When the jack load becomes zero, fixing (replacement) of the tendon material 4 is completed, and the tension force of the tendon material 4 is transmitted to the beam body 2 by the adhesive force with the filler 5. Therefore, as shown in FIG. 4B, the beam body 2 is formed with fixing portions Pa and Pa at both ends.

  After the completion of the second operation, the bearing plate 6, nut 6a, jack 7, jack chair 8 and coupler 9 are removed.

As mentioned above, according to the manufacturing method of the prestressed concrete member of this embodiment, since a fixing tool is not left on the end surface of the PCa beam 1, when installing the PCa beam 1, there is no member which obstructs attachment and bar arrangement. Therefore, the erection work can be easily performed.
In addition, when the fixing tool is disposed at the end, it is necessary to perform a rust prevention process or the like of the fixing tool, but according to the present embodiment, such a process can be omitted.

  Since a large-scale pretensioning device is not required, a high-quality prestressed concrete member can be manufactured even in a construction site where the work space is limited.

  In addition, the pressure bearing plate 6, the nut 6a, the jack 7, the jack chair 8, the coupler 9 and the like can be used for manufacturing other PCa beams, which is economical.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and it goes without saying that the above-described constituent elements can be appropriately changed without departing from the spirit of the present invention.

  For example, although the said embodiment demonstrated the case where a beam was manufactured with the manufacturing method of a prestressed concrete member, the concrete member which can be manufactured with the manufacturing method of a prestressed concrete member is not limited to a beam. For example, you may employ | adopt for manufacture of a floor slab, a pillar, etc.

  Further, in the fixing step, tension force may be reintroduced from both ends with respect to the tension material 4. As a result, it is not necessary to divide the work in the fixing process twice.

1 PCa beam 2 Beam body (concrete member)
3 Sheath tube (insertion hole)
4 Tensile material 5 Filler 6 Bearing plate

Claims (2)

A tensioning step of inserting a tensioning material into the insertion hole formed in the concrete member and a pressure bearing plate disposed on both end faces of the concrete member and introducing a tensioning force to the tensioning material;
A compression step of introducing prestress into the concrete member via the support plate by releasing the tension of the tendon;
A filling step of filling the insertion hole with a filler;
After the strength of the filler is expressed, a fixing step of reintroducing tension to the tension material, releasing the reintroduced tension force to fix the tension material, and removing the bearing plate. A method for producing a prestressed concrete member, comprising: In the fixing step, after reintroducing tension force from one end to the tension material, a first fixing operation of removing the pressure plate arranged on one end side while releasing the tension force;
And a second fixing operation of removing the support plate disposed on the other end side while releasing the tension force after reintroducing the tension force from the other end to the tension material. The manufacturing method of the prestressed concrete member of Claim 1.

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