JPH0126952B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is an unbonded system that eliminates the tensioning column type.
This relates to the construction method of prestressed concrete cylindrical structures using prestressed steel materials, including water storage tanks,
It can be used for LNG tanks, oil tanks, and other silos.

[Conventional technology] Prestressed concrete (PC) structure or prestressed reinforced concrete (PRC) using unbonded PC steel in the hoop (circumferential) direction
Compared to reinforced concrete container structures, cylindrical container structures such as silos have thinner walls and fewer reinforcing bars, making them more economical and more secure against cracks. This has the advantage of improving the watertightness of objects.

In addition, unbonded PC steel has a smaller coefficient of friction against curvature than bonded PC steel, so putting it in the direction of the hoop will cause a cylindrical container structure that will generate a large tensile force in the direction of the hoop due to the pressure of the contents. has a large effect.

[Problem that the invention seeks to solve]

However, conventional PC or PRC container structures often have pillars 2 for tensioning, as shown in FIG. 2, and therefore have the following drawbacks.

(1) Although the cylindrical container structure 1 is structurally a cylindrical shell structure, the tensioning column type 2 is a useless part for the shell structure.

(2) Traditionally, the cylindrical container structure 1 is often constructed using the sliding form method, but if the tensioning column type 2 is used, special formwork and equipment are required, and the construction becomes complicated, so the column type is used. Traditional without
Construction costs are higher than RC cylindrical structures.

(3) Post-casting of concrete at the tensioning end after tensioning is difficult to construct, as it is difficult to hold the formwork.

This invention aims to improve the economical efficiency and workability of such cylindrical structures, especially container structures, by constructing an unbonded prestressed structure that omits the tension column type using a sliding form construction method. .

[Means for solving problems]

The cylindrical structure according to the present invention is a cylindrical structure in which unbonded PC steel is arranged in the hoop direction (circumferential direction) and tension is introduced into the unbonded PC steel. A notch is provided, and the end of the unbonded PC steel material is fixed with tension introduced into the notch. in this case,
The tensioning column that protrudes outward is omitted, and a wall of approximately constant thickness is formed around the entire circumference, and after tensioning, the notch is coated with adhesive and filled with non-shrinkage mortar. Cross-sectional defects can be compensated for by filling, etc.

In addition, if the vertical spacing of the unbonded PC steel material is small and cross-sectional defects pose a problem in terms of strength, the tensioned ends should not be placed at the same location, but alternately placed at two slightly shifted locations.

For construction, the conventional sliding form construction method can be used, in which a yoke that holds opposing sliding formwork (sheathing boards) at a predetermined interval is pulled up along a vertical rod built into the wall. While doing so, concrete was poured and the walls of the cylindrical structure were successively constructed. For the notch, a notch formwork that matches the shape of the notch is attached to an anchor plate placed at a predetermined position within the cross section of the wall of the cylindrical structure. In addition, the end of the unbonded PC steel material placed in a predetermined position is passed through the circumferential insertion hole provided in the notch formwork, and in that state, concrete is successively poured using the sliding form method to achieve the predetermined strength. Introduce tension to the unbonded prestressed steel material in the areas where it has been secured. The anchor plate, notch formwork, etc. are installed as the sliding form progresses, and the notch formwork can be used repeatedly for the construction of the upper part.

The upper and lower notch formworks are connected using stationary formwork, and if sliding formwork is not used for the notch position, fill the notch formwork with concrete leakage material and use the sliding form method. Concrete is poured, and after the concrete has hardened, the cutout formwork and the standing formwork are removed, and the wall portions are successively constructed. In this case, the notch part formwork and the placing formworks above and below the notch part formwork do not move, but the sliding formwork moves with them sandwiched therebetween.

In addition, if the end of the unbonded PC steel material fits within the notch formwork, attach a removable cover to the wall surface side of the notch formwork, place the unbonded PC steel material in a predetermined position, and then After passing the section through the insertion hole of the cutout formwork, a lid is fitted, and concrete is poured using the sliding form construction method, and the wall sections are successively constructed. In this case, the sliding formwork moves on the lid of the notch formwork.

〔Example〕 Next, a description will be given based on the illustrated embodiment.

FIG. 3 shows a cross section of the cylindrical structure 1 according to the present invention, and shows the tensioning column type 2 (usually provided at 2 to 6 locations depending on the diameter of the structure) in the conventional example shown in FIG. ) is omitted.

FIG. 1 shows the details of the tensioned part of the unbonded PC steel material 3. A notch 4 is provided on the outer wall surface of the cylindrical structure 1, and the tensioned end of the unbonded PC steel material 3 is inserted into the notch 4. 5 is included. After tensioning, adhesive is applied to the notch 4 and non-shrinkable mortar 8 is filled. 6 in the figure is the tensioned end 5
Anchor plate 7 is an anchor bar for fixing.

Furthermore, in order to reduce cross-sectional loss due to the notch 4, the end of the unbonded PC steel material 3 is provided with a curvature in the direction opposite to the hoop direction. Preferably, the curvature R' is approximately equal to the curvature R of the wall portion to prevent stress concentration.

In addition, tensioning jacks are used to tension the PC steel, but if the jacking hits the wall, it can be countered by attaching a guide attachment to the tip of the jacking.

Figures 10 and 11 show the construction using the sliding form construction method, in which the sliding formwork 10 is placed at predetermined intervals (the interval can be adjusted).
While pulling up the yoke 9, which is held by the cylindrical structure 1, along the rod 16 vertically erected within the wall of the cylindrical structure 1, concrete for the wall is successively poured. To pull up the yoke 9, use the lower chord member 11 of the yoke 9.
This is done by holding the rod 16 with a center hole jack 12 attached to the center hole jack 12. Further, an internal working floor 13 and an external working floor 14 are provided on both sides of the yoke 9. Furthermore, a beam 15 having guide rollers 24 in the hoop direction is provided between the lower chord members 11 of the yoke 9, and the unbonded PC steel material 3 is first fed into the rollers 24, and the rollers 15 are moved as shown by the arrows in FIG. 24 into a predetermined position.

The procedure for disposing the unbonded PC steel material 3 in this device is as follows.

Place the unbonded PC steel material 3 on the internal working floor 13 or external working floor 14 near the tensioned end.

One end of the unbonded PC steel material 3 is pulled and carried to a predetermined position while being placed on the rollers 24 of the yoke 9.

Lowered from roller 24, it also served as width-stopping reinforcing bar.
Place on reinforcing bars for PC steel placement.

Adjust the position of the unbonded PC steel material 3 and insert the end into the hole of the fixing tool.

Figures 4 to 6 and Figures 7 to 9 respectively relate to the treatment of the notch 4 during construction by the sliding form construction method, and show the installation state of the notch formwork 19 and It shows the shape.

(a) Standing formwork method Figure 4 shows a case where the unbonded PC steel material 3 does not fit into the notch formwork 19 during concrete pouring, and the tension part of the unbonded PC steel material 3 is placed in the shape of the notch part 4. The matched notch formwork 19 is installed, and the upper and lower notch formworks 19 are connected by a standing formwork 20. FIGS. 5 and 6 show pipe-shaped and box-shaped notch forms 19, which can be made of iron plate or the like with a thickness of 2 to 3 mm.

The construction procedure in this case is as follows.

Attach anchor plate 6 to properly positioned anchor support 18.

The cutout formwork 19 is attached to the anchor plate 6 by tightening bolts.

Attach the stationary formwork 20 and remove the notch formwork 19.
and tighten the bolts.

The unbonded PC steel material 3 is placed, and its ends are inserted into the insertion hole 23 of the anchor plate 6 and the insertion hole 21 of the cutout form 19.

Sponge foam is packed into the cutout formwork 19 as a concrete leakage material.

Concrete is placed using the sliding form method, but the notch part formwork 19
is connected to the formwork support and will not slide.

After the concrete hardens, remove the formwork.

The used cutout formwork 19 is cleaned and used again in the upper part.

(b) A method in which the notch part also slides Figure 7 shows a case where the unbonded PC steel material 3 is accommodated in the notch part formwork 19 using the fixing part screw method, etc., and the wall surface side of the notch part formwork 19 is A removable lid 22 is provided on the top surface of which a sliding formwork 10 in the sliding form construction method can slide. FIG. 8 and FIG. 9 show a pipe type and a box type, respectively.

The construction procedure in this case is as follows.

Attach anchor plate 6 to properly positioned anchor support 18.

The cutout formwork 19 is attached to the anchor plate 6 by tightening bolts.

The other end of the cutout formwork 19 is attached to the support reinforcing bar 25 (or angle).

The unbonded PC steel material 3 is placed, and its ends are inserted into the insertion hole 23 of the anchor plate 6 and the insertion hole 21 of the cutout form 19.

The lid 22 of the cutout formwork 19 is fitted.

Concrete will be placed using the sliding form method.

After the concrete hardens, the lid of the notch formwork 19 is opened and removed.

The used cutout formwork 19 is cleaned and used again in the upper part.

[Effects of the Invention] By eliminating the tension column type of the prestressed concrete cylindrical structure, it is possible to construct it using the sliding form construction method in the same way as a normal concrete cylindrical structure.

If the end of the unbonded PC steel material is to fit inside the notch formwork, attach a removable cover to the wall surface side of the notch formwork to move the sliding formwork into the notch formwork. It can be installed by moving the lid, and the normal sliding form construction method can be applied as is. Therefore, the construction work of the prestressed concrete cylindrical structure is significantly reduced, and the workability is improved.

Even if the end of the unbonded PC steel material does not fit within the notch formwork, it is only necessary to use the notch formwork and stationary formwork in the vertical direction of the tensile end position of the notch. Since there are no obstacles, the sliding form construction method allows for efficient construction.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a tensioned part in an embodiment of the present invention, Figure 2 is a cross-sectional view of a cylindrical structure using conventional unbonded PC steel, and Figure 3 is a cross-sectional view of an embodiment of this invention. Figures 4 to 9 show the notch formwork, Figures 4 and 7 are cross-sectional views in use, Figures 5 and 6,
8 and 9 are perspective views, FIG. 10 is a vertical sectional view showing the state of construction by the sliding form construction method, and FIG. 11 is an enlarged view of section A in FIG. 10. 1... Cylindrical structure, 2... Tension column type, 3...
...Unbonded PC steel material, 4... Notch, 5...
tension end, 6... anchor plate, 7... anchor bar, 8... mortar, 9... yoke, 10...
...Sliding formwork, 11...Lower chord material, 12...
... Jack, 13 ... Internal work floor, 14 ... External work floor, 15 ... Beam, 16 ... Rod, 17 ...
Reinforcing bar, 18... Fixture support, 19... Notch part formwork, 20... Stationary formwork, 21... Insertion hole, 22
... Lid, 23 ... Insertion hole, 24 ... Roll, 25 ...
...Reinforcing bars for support.

Claims (1)

[Claims] 1. Unbonds arranged in the circumferential direction of a cylindrical structure
A cylindrical structure in which a notch is provided on the outer wall surface of the tensioned end of the prestressed steel material instead of a tensioning column that protrudes outward, and the end of the unbonded prestressed steel material is fixed within the notch. In this method of constructing a prestressed concrete cylindrical structure, first, an anchor plate is placed at a predetermined position in the cross section of the wall of the cylindrical structure to be constructed, and a cut having a through hole in the circumferential direction of the wall is inserted. After installing the notch part formwork and connecting the upper and lower notch part formworks with a placing formwork, placing the unbonded PC steel material in a predetermined position and passing the end through the insertion hole of the notch part formwork, Fill the notch formwork with concrete leakage material and use the sliding form construction method.
Concrete is poured while pulling up the yoke that holds the opposing sliding formwork at a predetermined interval along a vertical rod built into the wall, and after the concrete has hardened, the notch formwork is placed. and a method for constructing a prestressed concrete cylindrical structure, which comprises removing the standing formwork, sequentially constructing wall parts, and introducing tension force into the unbonded prestressed steel material. 2 Unbonds arranged in the circumferential direction of a cylindrical structure
A cylindrical structure in which a notch is provided on the outer wall surface of the tensioned end of the prestressed steel material instead of a tensioning column that protrudes outward, and the end of the unbonded prestressed steel material is fixed within the notch. A method for constructing a prestressed concrete cylindrical structure, in which an anchor plate is placed at a predetermined position in a cross section of a wall of a cylindrical structure to be constructed, and an anchor plate is provided with an insertion hole in the circumferential direction of the wall. , Attach a notch formwork with a removable lid to the surface side of the wall, place the unbonded PC steel material in a predetermined position, and pass the end through the insertion hole of the notch formwork. The lid is fitted, and concrete is poured using the sliding form construction method while pulling up the yoke that holds the opposing sliding formwork at a predetermined distance along the vertical rod built into the wall. A method for constructing a prestressed concrete cylindrical structure, characterized in that after curing, the notch part formwork is removed and the wall parts are successively constructed, and tension force is introduced into the unbonded PC steel material.