JP3013354B2 - Pretension type PC member formwork - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretension type PC member formwork.

[0002]

Conventionally, this type of pretension type PC (prestressed concrete) member, for example, a PC girder used for a main girder of a prefabricated PC cover or a main girder of a road protection shed, is shown in FIG. As shown in
It is composed of a flange portion 1, a web portion 2, and a cross beam portion 3,
The pretension is given by the PC steel material 4. By the way, in order to mold the above-mentioned conventional PC girder into concrete by the pretension method, first place the PC steel material 4 in a formwork and apply tension, and then cast concrete in the formwork and set the tension after hardening. Was released to give prestressed concrete, and after the prestressing was given in this way, demolding was performed. For this reason, a compressive force acts on the concrete molded product by releasing the tension and giving a prestress, and the flange portion 1 and the web portion 2 contract in the direction of the PC steel material 4, that is, in the longitudinal direction, and as shown in FIG. In the case of having a plurality of portions 3, the compressive force causes the inner side surface 5 of the cross beam portion 3 on both sides in the longitudinal direction to press against the formwork, making it difficult to remove the mold. There is a problem that the inner surface 5 is locally damaged. For this reason, the draft angle of the cross beam part is made large, or the mold is divided into two parts in the horizontal direction and left or right. There is known a device that releases a prestress by releasing the same.

However, in the case where the above-mentioned mold is divided into right and left, assembling and disassembling operations of the divided mold are complicated, and it is difficult to avoid an increase in manufacturing cost. It is difficult to use a lifting method that lifts a concrete molded product by fixing the formwork with the prestressing method.In practice, PC concrete tensioning devices are arranged on both sides of the formwork and the concrete molded product is lowered. After demolding, prestressing is applied. In this case, it takes time and effort as compared with the pull-up demolding method, and the concrete molded product and the PC steel tensioning device are fixed at a certain height, and these are fixed. On the other hand, the work is difficult because the mold is pulled down and the mold is removed, and when this type of integrated mold is used, in addition to the prestressed PC steel material, Longitudinal shrinkage occurs in the concrete moldings by curing of the concrete, results in pressure contact between the inner surface and the mold of the cross beam portion by the compression force, there is a problem that demolding becomes difficult by this pressure.

In view of the above, the present invention is intended to prevent a local breakage of a cross beam when a concrete preform having a plurality of cross beams on one side is subjected to a vertical prestress.
An object of the present invention is to provide a pretension type PC member mold excellent in mold removal workability and easy to assemble and disassemble the mold.

[0005]

According to a first aspect of the present invention, there is provided a mold for manufacturing a PC member having a plurality of cross beams on one side and pretensioning in a longitudinal direction. The central form part including the portion is formed separately from the form parts on both sides in the vertical direction, and the central form part is formed so as to be movable in one side direction, and after the concrete is hardened,
By moving the central form part in one direction, the form is disassembled into the central form part and the form parts on both sides. The formwork portion is moved, thereby preventing stress concentration between the cross beam portion and the formwork.

According to a second aspect of the present invention, the interval between the joining portions on both sides in the longitudinal direction of the central form is enlarged toward one side, and the central form is enlarged toward one side. Therefore, a gap is created between the central mold part and the mold parts on both sides by slightly moving the central mold part to the other side, and the mold parts on both sides can be moved by this gap. Become.

According to a third aspect of the present invention, a flange portion is provided at a joint portion between the center mold portion and the mold portions on both sides in the longitudinal direction, and at least one of the joint portions is provided with a flange from the one side. A long hole is formed in the direction toward the side, and a rod-shaped member is inserted into this long hole, and while the rod-shaped member is inserted in the long hole, the central form part is moved to one side by the length of the long hole. Accordingly, the center mold portion and the mold portions on both sides can be easily disassembled, and the assembly can be easily performed by moving to the other side by the length of the long hole.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 4 show an embodiment of the present invention, in which the same parts as those in FIG. 6 are denoted by the same reference numerals, and the manufacturing of a PC girder as a PC member shown in FIG. 6 will be described as an example. Of the PC girder (hereinafter, referred to as a mold). The mold 10 includes a longitudinal flange molding portion 11 and a web molding portion.
12 and a horizontal beam forming portion 13 as a horizontal beam portion, and the horizontal beam forming portion 13 is provided at three positions, that is, the center in the vertical direction and the left and right. Further, the flange forming section 11 is provided with a lower surface portion 11A forming the lower surface of the flange portion 1 integrally with the formwork 10, and around the lower surface portion 11A, a side plate portion 14 separate from the formwork 10 is attached and detached. In this example, the side surface portion 14 is formed by providing the angle iron 14A with a fixing member 14B such as a bolt and a nut.

Further, by separating the central mold portion 15 including the horizontal beam forming portion 13 at the center in the vertical direction from the mold 10, the mold 10 is separated from the central mold portion 15 on both sides in the vertical direction. The middle form part 15 is divided into three parts
The distance H between the joining portions on both sides in the vertical direction is increased from one side to the other side, that is, from above to below. Further, plate-shaped flange portions 15A, 16A, 17A are provided at joints between the center mold portion 15 and the mold portions 16, 17, respectively. The flange portions 15A and 16A, the flange portions 15A and The part 17A is superimposed. Also, the lower portions of the flange portions 15A and 16A are obliquely provided on the mold portion 16 side, and the lower portions of the flange portions 15A and 17A are obliquely provided on the form portion 17 side. That is, the flange portion 15A and the flange portion
The spacing between the flange 16A and the flange 15A and the flange 17A is formed so as to expand downward. Furthermore, the flanges 15A, 16
A and 17A are respectively provided with a vertically long hole 18 and a circular positioning hole 19, and a bolt 20 for tightening and fixing the overlapping flange portions 15A, 16A and 17A is inserted into the long hole 18. A nut 21 is screwed onto the bolt 20 which is a rod-shaped member, and a fixing member 22 is formed by the bolt 20 and the nut 21. The taper pin 23 serving as a positioning pin is inserted. Reference numeral 24 in the figure is a table on which the mold portions 16 and 17 on both sides are placed.

[0010] However, by the pretension method, the PC
In order to form a girder, first, as shown in FIG. 2, a PC steel material 4 such as a PC steel wire is placed on a mold frame 10 and tension is applied by a conventional method. Thereafter, concrete is poured into the formwork 10 and the concrete is hardened while tension is applied to the PC steel material 4. Then, the angle iron 14A is removed, and the nut 21 of the fixing member 22 is loosened. At the same time, by pulling out the tapered pin 23 and moving the central form part 15 downward along the long hole 18 direction, the overlapping flange parts 15A, 16A,
A gap S is formed between 17A. After the mold 10 is disassembled in this manner, the tension of the PC steel material 4 is released, and the PC member is released.
Lift and remove 25. In this case, before the PC member 25 is prestressed, the tension of the PC steel material 4 is released by moving the central form part 15 downward, so that the form parts 16 and 17 on both sides move to the center side. Thus, the PC member 25 can be easily removed without absorbing the contraction of the PC member 25 and pressing the PC member 25 against the cross beam forming portion 13. Then, in order to assemble the mold 10, the center mold portion 15 is moved upward, and the positioning holes 19, 19 of the respective flanges 15A, 16A, 17A are moved.
The taper pin 23 is inserted into the nut to perform positioning, and the nut 21 is tightened to assemble. In the above description, the nut 21 is loosened, but the nut 21 is not removed from the bolt 20, and the central form part 15 is moved with the bolt 20 inserted into the elongated holes 18.

As described above, in this embodiment, a plurality of cross beams 3, 3, 3 are provided at a lower portion on one side according to the first aspect.
In a mold for manufacturing a PC member 25 provided with a pretension in the vertical direction, a transverse beam forming portion 13 serving as a lateral beam portion of the mold 10 is provided.
The central formwork part 15 including the formwork parts 16 and 17
Since it is formed separately and the central form part 15 is formed so as to be movable downward in one side direction, after the concrete is hardened, by moving or removing the central form part 15 downward. The formwork 10 is disassembled into a central formwork part 15 and formwork parts 16 and 17 on both sides, and the formwork parts 16 and 17 on both sides move in response to the contraction of the concrete molding due to the pretension of the PC steel 4. In addition, stress concentration between the cross beam 3 and the formwork 10 is prevented, and a PC member as a concrete molded product is formed.
25 can be prevented from being locally damaged, and can be easily removed from the mold. For this reason, the occurrence of local stress due to shrinkage of the concrete molded product is also prevented in the formwork 10, the durability of the formwork 10 is improved, and the formwork strength is relatively small as compared with the related art, Its structure can also be simplified. Further, the draft angle of the cross beam portion 3 is small and can be made almost vertical, so that an economical and rational product structure can be obtained.

Further, as described above, according to the present embodiment, claim 2
In response to the above, since the interval H between the joint portions on both sides in the vertical direction of the central form part 15 is formed to be enlarged downward, the central form part 15 can be moved only slightly downward, A gap is formed between the mold section 15 and the mold sections 16 and 17 on both sides, and the mold sections 16 and 17 on both sides can be moved by the gap, so that the movement amount of the central mold section 15 is small. For formwork
10 can be easily disassembled and assembled.

Further, in this embodiment, the central form part 15 and the form parts on both sides in the vertical direction are corresponding to the third aspect.
Flanges 15A, 16A, and 17A are provided at joints with the flanges 16 and 17, and long holes 18 are formed in the flanges 15A, 16A, and 17A in a direction from bottom to top, that is, in a vertical direction. A bolt 20, which is a rod-shaped member, is inserted into the 18, 18, and the central form part 15 is moved downward by the length of the long hole 18 while the bolt 20 is inserted in the long hole 18, so that the central form part 15 and the mold portions 16 and 17 on both sides can be easily disassembled, and the assembly can be easily performed by moving upward by the length of the long hole 18. Also, as an effect on the embodiment, since the rod-shaped member is the bolt 20 of the fixing member 22, the work can be performed without removing the fixing member 22 only by loosening the fixing member 22, so that the central form part 15 falls off and comes off. Therefore, at the time of assembling, the mold 10 can be easily assembled with the fixing member 22 by slightly moving upward as it is.

Further, as an effect of the embodiment, the taper pin 23 as a positioning pin is inserted into the positioning holes 19 of the overlapping flange portions 15A, 16A, 17A.
At the time of assembly, the central form part 15 and the form parts 16 and 17 on both sides are formed.
Can be easily performed. In addition, collar 15
A and the flange 16A are inclined at one side to the formwork portion 16 side,
The flange 15A and the flange 17A are inclined at one side to the frame 17 and the flanges 15A, 16A and the flanges 15A, 17A form a C-shape that expands downward. At the time of pulling out, the flanges 15A, 16A and the flanges 15A, 17A can be moved smoothly without sliding resistance, and the flanges 15A, 15A can be aligned with the flanges 16A, 17A at the time of assembly. Assembly work is also facilitated.

FIG. 5 shows a second embodiment of the present invention, in which the same parts as those in the first embodiment are denoted by the same reference numerals, and the detailed description thereof is omitted. The elongated hole 18 is formed in 15A, and a hole 26 such as a circle for inserting the bolt 20 or a screw hole into which the bolt 20 is screwed is provided in the flange portions 16A and 17A. If the long hole 18 is provided in at least one of the flange portions 15A, 16A, 17A, the central mold portion 15 can be moved without removing the nut 21 from the bolt 20.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, the shape and dimensions of a concrete molded product can be appropriately selected, and the number of cross beams may be four or more. Further, the present invention can be applied to a concrete molded product having only a cross beam portion and no web portion. Further, various rod-shaped members other than bolts can be used as the rod-shaped member. Further, in the first and second aspects, the fixing member may be removed to move or remove the central form part 15.

[0017]

According to a first aspect of the present invention, there is provided a mold for manufacturing a PC member having a plurality of cross beams on one side and pretensioning in a vertical direction, the center including a cross beam portion of the mold. The formwork portion is formed separately from the formwork portions on both sides in the vertical direction, and the central formwork portion is formed so as to be movable in one side direction. It is possible to provide a pretension type PC member mold excellent in mold workability and easy to assemble and disassemble the mold.

According to a second aspect of the present invention, the interval between the joining portions in the longitudinal direction of the central form portion is formed so as to increase toward one side. It is possible to provide a pretension type PC member formwork excellent in workability and easy to assemble and disassemble the formwork.

According to a third aspect of the present invention, a flange portion is provided at a joint between the center mold portion and the mold portions on both sides in the longitudinal direction, and at least one of the joint portions is provided with another flange from the one side. Long holes are formed in the direction toward the side, and rod-shaped members are inserted into these long holes to prevent local breakage of the cross beam, excellent demolding workability, and assembly and disassembly of the mold Can be easily provided.

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of the present invention, in which a central mold portion is moved to one side.

FIG. 2 is a side view of the mold showing the first embodiment of the present invention.

FIG. 3 is a sectional view of a mold showing the first embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a flange showing the first embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a flange showing a second embodiment of the present invention.

FIG. 6 is a partially cutaway perspective view of a PC girder.

[Explanation of symbols]

 3 Cross beam part 10 Formwork 15 Central formwork part 16 17 Formwork parts on both sides 15A 16A 17A Flange part 18 Long hole 20 Bolt (bar-shaped member) 25 PC member H space

(56) References JP-A-5-138639 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B28B ⁷ /00-7/46 B28B 23/00-23 / 22 E01F 7/04

Claims (3)

(57) [Claims] 1. A mold for manufacturing a PC member having a plurality of cross beams on one side and pre-tensioned in a vertical direction, wherein a central frame portion including a cross beam portion of the mold is vertically aligned. A mold for a pretensioning type PC member, wherein the mold is formed separately from the mold parts on both sides, and the central mold part is formed so as to be movable in one direction. 2. The pretensioning type PC member formwork according to claim 1, wherein the space between the two joining portions in the longitudinal direction of the central formwork portion is enlarged toward one side. 3. A flange portion is provided at a joint portion between the central mold portion and the mold portions on both sides in the vertical direction, and at least one of the joint portions is provided in a direction from the one side to the other side. 3. The pretensioning method according to claim 2, wherein a long slot is formed, and a rod-shaped member is inserted into the long slot.
Form of C member.