JP2014008649A - Formwork structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repeatedly-usable formwork structure capable of manufacturing a high-quality PC member inexpensively.SOLUTION: A formwork structure 1 for manufacturing a PC member into which prestress is introduced by a pre-tension method includes a formwork pedestal 2, a formwork body 3 placed on the formwork pedestal 2, a friction reducing member 4 interposed between the formwork pedestal 2 and the formwork body 3, and a fixing member 5 penetrating the formwork body 3, and can reduce or remove a force applied to the formwork body 3 when a tension force is released.

Description

  The present invention relates to a formwork structure used when a PC member is manufactured by a pretension method.

  Prestressed concrete members (hereinafter referred to as PC members), which have increased strength against tensile force and cracks by applying tension (compressive force) to the concrete in advance or after the concrete is hardened, are frequently used in the construction field. Has been. This pre-stress is introduced into the concrete via the adhesive force between a tension material such as a PC steel wire, a PC steel strand, and a PC steel bar, and the concrete. As a prestress introduction method, a tension force is introduced into the tension material in advance and the tension force is released after the concrete is hardened. There is a post-tension method to introduce.

By the way, when manufacturing a PC member by the pre-tension method, first, a tension side abut provided with a tension jack and a reaction force receiving side abut against the tension force are arranged to face each other at a predetermined interval. In the meantime, a mold for manufacturing the PC member is installed, and both ends of the tension member penetrating the side wall of the mold are fixed to the tension side abutment and the reaction force receiving side abutment. Before placing fresh concrete in the formwork, after introducing tension to the tension material with a jack, placing the concrete, waiting for its hardening and releasing the tension, A predetermined pre-stress is introduced into the.
As a prior art concerning the manufacturing apparatus of such a PC member (PC structure or PC plate), for example, an apparatus disclosed in Patent Document 1 can be cited.

JP 2007-16478 A

When the tension is released by loosening the jack or cutting the tension material, the tension material contracts and the concrete member is pulled to the reaction force receiving side abut side.
Therefore, a force due to the tensile force acts on the mold via the concrete member, but since a large frictional resistance acts on the lower surface of the mold, the force is received and the mold There was a risk that the mold would be deformed during repeated use of the frame.

  When the formwork is deformed, the quality of the product is deteriorated, so that the formwork cannot be reused. On the other hand, when the deformation of the formwork is suppressed by increasing the rigidity of the formwork, the formwork becomes expensive and the production cost of the product becomes expensive.

  The present invention aims to solve the above-mentioned problems, and provides a formwork structure that can be used repeatedly and that can manufacture a PC member with high quality and low cost. Is an issue.

  In order to solve the above problems, the present invention provides a formwork structure for manufacturing a PC member into which prestress is introduced by a pretension method, and is placed on the formwork base and the formwork base. And a friction reducing member interposed between the formwork cradle and the formwork body.

According to such a formwork structure, it is possible to reduce or eliminate the force acting on the formwork body when the tension force is released.
That is, when the tension material contracts when the tension force is released, the concrete member is pulled to one side, and a force acts on the formwork body via the concrete member, but the formwork body is placed on the formwork via the friction reducing member. Since it slides on the cradle, the stress acting on the mold can be reduced or eliminated.
Therefore, the mold body is not deformed, and the PC member can be manufactured with high quality even when the mold is repeatedly used.

  If the fixing member penetrating the mold body is provided and the tip of the fixing member is configured to be fixed to the mold base, the positioning and level adjustment of the mold body can be easily performed. Can do.

  According to the formwork structure of the present invention, it can be used repeatedly, and a PC member can be manufactured with high quality and low cost.

It is a perspective view which shows the formwork structure which concerns on embodiment of this invention. It is a cross-sectional view of the formwork structure shown in FIG. It is a top view which shows typically the use condition of a formwork structure.

  The formwork structure 1 of this embodiment is for manufacturing a PC member into which prestress is introduced by a pretension method. As shown in FIG. 1, the formwork base 2 and the formwork body 3 are used. And a friction reducing member 4.

The formwork cradle 2 is a so-called base that supports the formwork body 3 from below. In the present embodiment, the mold body 3 is supported by the two cradle components 20 and 20.
The cradle constituting material 20 is not limited as long as the upper surface is configured to be a flat surface and can support the mold body 3 with the surface. For example, H-shaped steel, square steel, etc. What is necessary is just to comprise by steel materials, a concrete member, etc. Moreover, it is not necessarily divided into a plurality of members of the form cradle 2 and may be constituted by one plate material.

Bolt holes (not shown) for fixing the front ends of the fixing bolts (fixing members) 5 are formed at both ends of the cradle component 20.
The arrangement and number of bolt holes are not limited. The bolt holes may be formed as necessary and may be omitted.

  In the present embodiment, the cradle constituent material 20 is arranged so that the longitudinal direction of the cradle constituent material 20 is in a direction orthogonal to the tension material 6. The orientation of the cradle component 20 is not limited and may be arranged in parallel with the tendon 6.

The mold body 3 is made of steel and includes a bottom frame 30 disposed on the bottom and a side frame 31 erected on the top surface of the bottom frame 30.
The mold body 3 can be fixed to the mold cradle 2 by a fixing member 5 penetrating the mold body 3.

  The bottom frame 30 is configured by a flat plate having a rectangular shape in plan view. The bottom frame 30 has a strength that does not bend due to the weight of the concrete, the side frame 31 and the like placed inside the mold body 3.

  Insertion holes (not shown) for inserting the fixing bolts 5 are formed at the four corners of the bottom plate 30. In addition, arrangement | positioning and the number of insertion holes are not limited. Moreover, what is necessary is just to form an insertion hole as needed, and may abbreviate | omit depending on the structure of a fixing member.

  In the present embodiment, the mold body 3 is disposed on the mold cradle 2 so that the end of the bottom plate 30 and the cradle component 20 coincide with each other. Any one of the side surfaces may protrude from the other.

  The side frame 31 is disposed in a rectangular shape in plan view so as to surround the four sides. The side frame 31 has a strength that is not deformed by the pressure of the concrete placed in the mold body 3.

In the present embodiment, a frame-shaped upper plate 32 that projects outward is disposed at the upper end of the side plate 31.
In the four corners of the upper plate 32, insertion holes (not shown) for inserting the fixing bolts 5 are formed corresponding to the positions of the insertion holes of the bottom frame 30. In addition, arrangement | positioning and the number of insertion holes are not limited. Moreover, what is necessary is just to form an insertion hole as needed, and may abbreviate | omit depending on the structure of a fixing member.

  A plurality of through holes 33, 33,... For inserting the tension members 6, 6,. In this embodiment, a total of 15 through-holes 33, 33,..., In three upper and lower rows and five rows are formed, but the number of through-holes 33 is not limited. Moreover, in this embodiment, although the through-hole 33 is not formed with respect to the surface orthogonal to the surface in which the through-holes 33, 33, ... were formed, even if the through-hole 33 is formed as needed, Good.

  The friction reducing member 4 is a sheet-like member interposed between the mold receiving base 2 and the mold main body 3, and the surface thereof is subjected to fluororesin processing. Since the friction reducing member 4 is interposed, the frictional resistance force between the mold receiving base 2 and the mold main body 3 is greatly reduced.

The friction reducing member 4 covers the entire upper surface of the mold receiving base 2.
In addition, the material which comprises the friction reduction member 4 is not limited, For example, a roller-shaped thing, a bearing, etc. may be sufficient.

Next, the manufacturing method of the concrete member using the formwork structure 1 is demonstrated.
First, as shown in FIG. 3, the tension members 6, 6,... Are inserted through the through holes 33, 33,.
At this time, the mold body 3 is fixed to the mold holder 2 via the fixing bolts 5, 5,.

Next, in a state where the tension members 6, 6,... Are tensioned, concrete is placed on the mold body 3 and cured.
The tension force is introduced into the tension member 6 via a jack or the like (not shown).

  When a predetermined strength develops after curing the concrete, the fixing bolts 5, 5,... Are removed to release the tension of the tension members 6, 6,.

When the tension of the tension members 6, 6, etc. by the jack is released, the tension members 6, 6, etc. contract and the concrete member is pulled to one side (the opposite side of the jack). When the concrete member is pulled, a force is also applied to the mold body 3, but the mold body 3 slides on the upper surface of the mold cradle 2 via the friction reducing member 4.
Therefore, since the stress acting on the mold body 3 can be reduced or eliminated, the mold body 3 is not deformed, and even when the repetitive mold structure 1 is used, the PC member can be used with high quality. Can be manufactured.

The mold body 3 can be easily returned to its original position by sliding on the friction reducing material 4.
The fixing bolt 5 can easily perform positioning and adjustment of the height position.

  The embodiment according to the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Formwork structure 2 Formwork base 3 Formwork body 4 Friction reduction member 5 Fixing member 6 Tension material

Claims (2)

A mold structure for producing a PC member into which prestress is introduced by a pretension method,
It comprises a formwork cradle, a formwork body placed on the formwork cradle, and a friction reducing member interposed between the formwork cradle and the formwork body, A formwork structure. A fixing member penetrating the mold body,
The formwork structure according to claim 1, wherein a tip of the fixing member is fixed to the formwork cradle.

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