JPH0782836A - U-shaped beam of precast prestressed concrete - Google Patents

Abstract

PURPOSE:To facilitate wiring execution by providing a diaphragm through which a secondary cable is passed to be joined a pillar and producing a force for bending up the diaphragm when the secondary cable is tensioned. CONSTITUTION:A U-shaped beam 1 is erected on a bracket notched in a pillar 10 and provided with a diaphragm 3 provided with an inserting hole through which a secondary cable 11 is passed through and tensioned to give a bending up-force to a diaphragm 3. After the U-shaped beam 1 is fixedly joined with the pillar 10, a third cable 15 is executed to place cram concrete 12 in the U-shaped beam 1 and erect slab concrete 13. Thus, a reasonable economical design coping with even a long span can be achieved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to precast prestressed concrete U-beams.

[0002]

2. Description of the Related Art Conventionally, a precast prestressed concrete beam has a U-shaped cross section to reduce the weight and facilitate erection work, and eliminates the need for a formwork when placing a cast-in-place concrete in the beam. , There is a technology that omits formwork support work and scaffold construction.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a precast prestressed concrete U-shaped beam which is capable of further improving the construction work by further improving the conventional technique. To do.

[0004]

SUMMARY OF THE INVENTION The present invention is a precast prestressed concrete U characterized by having a U-shaped trough in cross section, having at least one diaphragm, and having a PC cable insertion hole in this diaphragm. It is a cross beam.

[0005]

The precast prestressed concrete U-shaped beam of the present invention is manufactured by a pre-tensioning or post-tensioning method using a primary cable, has a U-shaped trough cross section, and has at least one diaphragm. . The diaphragm may be a wall body provided across the U-shaped groove of the U-shaped beam and may extend over the entire surface of the U-shaped groove, or the top of the wall may be lower than the top of the U-shaped trough. But it's okay. The dimension of the diaphragm in the thickness direction is also not limited. When a beam is provided at a right angle to the U-shaped beam, it is preferable to provide a diaphragm in accordance with the joining position of the beam.

The diaphragm is provided with a PC cable insertion hole through which a PC cable penetrates near the bottom. As a result, when the secondary cable is routed in the U-shaped groove of the precast prestressed concrete U-beam and the U-beam is coupled and fixed to the pillar, etc., the secondary cable is tensioned and bent up to the part where the diaphragm is provided. Power can be applied. This is the most characteristic action of the U-shaped beam of the present invention. The bending force of the secondary cable can efficiently support the weight of the filled concrete in the U-shaped groove and the weight of the beam or slab.

Since the U-shaped beam of the present invention has a groove-shaped opening, secondary cables and tertiary cables can be easily wired, no construction of a sheath or the like is required, and the filled concrete in the U-shaped groove is It is completely buried in concrete by placing and is most suitable for building structure. The U-shaped beam of the present invention is made of precast prestressed concrete, is lightweight, has high strength and is easy to handle before erection, does not require a large crane, etc., and can be used for formwork and support work when pouring medium-filled concrete. Is unnecessary and the bracket may be small.

[0008]

EXAMPLE FIG. 1 shows a perspective view of a precast prestressed concrete U-shaped beam 1 of an example. 2 shows a cross section of the trough portion of the U-shaped beam 1, and FIG. 3 shows a cross section of the diaphragm 3 portion. Note that FIG.
Although the stirrup muscle 5 is omitted in FIG. 2, it is shown in FIGS.

In the embodiment shown in FIG. 1, the beam back is 850 mm and the beam width is 6
50 mm, beam length 9000 mm, wall thickness 150 mm, U-shaped trough cross section, thickness 500 mm at the center in the longitudinal direction
The U-shaped beam 1 is provided with the diaphragm 3. As shown in the cross section of the U-shaped beam 1 in FIG.
C-strand 4 (primary cable) is arranged and pre-stress is introduced by the pre-tension method. The stirrup bar 5 is for integrally connecting the U-shaped beam and the slab concrete.

FIG. 3 shows a portion U provided with the diaphragm 3.
The cross section of beam 1 is shown. In the embodiment, the top surface of the diaphragm 3 coincides with the top surface of the beam, but it may be lower than this. The diaphragm 3 has an insertion hole 6 for the secondary cable.
An insertion hole 7 for the tertiary cable is provided so as to penetrate in the longitudinal direction of the beam. The insertion hole 6 for the secondary cable is provided near the bottom of the diaphragm 3. The insertion hole 7 for the tertiary cable is provided above it. The secondary cable fixes a beam to a column or the like and bears a stress due to a work load or its own weight such as a slab, and the tertiary cable bears a stress due to an earthquake or a load.

FIG. 4 is an explanatory view of the construction work for constructing the precast prestressed concrete U-shaped beam 1 of the embodiment between the columns 10, 10. The U-shaped beam 1 of the embodiment is erected on the notch provided in the pillar 10 as a bracket, the secondary cable 11 is inserted, and the U-shaped beam 1 is connected to the pillar 10. Figure 4
Then, a large number of continuous U-shaped beams 1, 1, ...
A secondary cable 11 passing through 0, 10, ... Is collectively connected. Secondary cable 11 is diaphragm 3
The diaphragm 3 is strained by passing through the insertion hole provided in
Bending force is applied to. FIG. 5 illustrates this, and shows a state in which the U-shaped beam 1 is coupled to one column 10. Since the secondary cable 11 is strained through the lower end of the top surface of the diaphragm 3, a bending up force indicated by an arrow 14 is generated.

After the U-shaped beam 1 is bonded and fixed to the pillar 10, a tertiary cable 15 is installed and, as shown in FIG. 4, a filled concrete 12 of the U-shaped beam 1 is poured. At this time, U-shaped beam 1
Since it also serves as a formwork, there is no need for a formwork and its support work. Further, since the secondary cable and the like are buried in concrete, grouting is not required and the requirements for the cable for building structure are satisfied. Further, since the filled concrete can be a concrete having low strength, it is also advantageous in terms of cost.

After that, a slab concrete 13 is cast in place by installing a formwork and supporting works for the floor portion, or a precast slab is installed to form a floor slab. When a beam is provided at a right angle to the U-shaped beam, it is preferable to provide a diaphragm in accordance with the joining position of the beam. FIG. 6 is a plan view of a beam and a column for explaining this. Large U between the pillars 10, 10, ...
The girders 1, 1, ... Are erected, and the small beam 21 is erected between the large U-shaped beams 1, 1. In this case, a diaphragm 3 is provided at the portion of the large U-shaped beam 1 to which the beam 21 is joined so that it can be bent up by a secondary cable so that the load of the beam 21 can be sufficiently supported. To do. The beam 3 itself is also provided with the diaphragm 3 so that it can be bent up,
By supporting the weight of the beam 21 itself, the work load, the load of the slab 22 and the like, the cross section of the beam 21 can be made smaller, and in combination with the U-shaped cross section, the present invention is realized. The advantages of the U-beam can be fully exhibited.

In the above embodiments, the U-shaped beams have the same vertical width, but it is more preferable that the U-shaped beams have a U-shape that is close to the V-shape with the upper side open. The number of diaphragms is
The beam span length, the number of beam beams orthogonal to the U-shaped beam 1 and the like are taken into consideration to appropriately determine.

[0015]

EFFECTS OF THE INVENTION The precast prestressed concrete U-shaped beam of the present invention can be manufactured in a large amount with high strength and high quality by the pretensioning method, and is lightweight and easy to transport. A large crane is not required even during installation, and the support bracket can be supported by a small one. After installation, the corresponding load can be divided between the secondary and tertiary cables and the cable can be installed at the required position. By installing a number of diaphragms, it is possible to apply the necessary bending-up force, and a rational and economical design that can handle long spans can be achieved.

Further, since the secondary and tertiary cables are arranged in the groove-shaped opening, the construction is easy. Also U
Low strength concrete is sufficient for the concrete of the beam, and the cast-in-place concrete can be greatly reduced by using the precast plate for the floor, which does not require formwork or support. It can be expected to save labor and shorten the construction period.

[Brief description of drawings]

FIG. 1 is a perspective view of a precast prestressed concrete U-shaped beam of an embodiment.

FIG. 2 is a cross-sectional view of the U-shaped trough of the precast prestressed concrete U-shaped beam of the embodiment.

FIG. 3 is a cross-sectional view of the diaphragm portion of the precast prestressed concrete U-shaped beam of the embodiment.

FIG. 4 is an explanatory view of erection of the beam of the embodiment.

FIG. 5 is an explanatory diagram of bending up of the beam of the embodiment.

FIG. 6 is a plan view of the structure of the beam and the pillar according to the embodiment.

[Explanation of symbols]

1 U-shaped Beam 2 U-shaped Groove 3 Diaphragm 4 PC Strand (Primary Cable) 5 Stirrup Bar 6 Insertion Hole for Secondary Cable 7 Insertion Hole for Tertiary Cable 10 Pillar 11 Secondary Cable 12 Filled Concrete 13 Slab Concrete 14 Arrow (bending force) 15 Tertiary cable 21 Beam 22 Slab

Claims (1)

[Claims] 1. A precast prestressed concrete U-shaped beam having a U-shaped trough in cross section, having at least one diaphragm, and having a PC cable insertion hole in the diaphragm.