JPH0369749A - Compound pc slab - Google Patents

Abstract

PURPOSE:To obtain a PC slab of thin make by installing a girder flat beam with prestressing steels embedded therein over a space between columns, by installing beams for binders with prestressing steels embedded therein over a space between the flat beams and by making both of them integral with concrete cast in site. CONSTITUTION:Steels 7 for bond prestressing are inserted into a girder flat beam 5 and tie hoops 8 and main reinforcements 9 are bonded to the flat beams. Between the flat beams 5, a binder member 3 is formed of beams 10 for binders and concrete 6 cast in site for making a floor slab. The steels 7 for bond prestressing are also embedded in the beams 10 for binders and prestress is give thereto. Then prestressing steels for secondary stress are installed between the beams 10 for the binders and partial stress is given thereto, and unbond cables 13 are anchored with stress to precast boards 12. Thereby highly economical PC slabs can be obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a precast concrete (hereinafter referred to as PC) member in which prestress is applied to the entire floor slab and a cast-in-place concrete member.
The present invention relates to a composite PC slab synthesized by C floor slab.

<Prior art> As shown in Figs. 7 and 8, the conventional I) C slab is formed by integrally forming the main beam part 21, the small beam part 22, and the floor slab part 23 with cast-in-place concrete. MIMk throughout the area
! Generally, an unbonded cable 24 was buried in the concrete, and prestress was applied after the concrete hardened.

This kind of conventional PC slab is also called a flat slab, and the large beam part and, in some cases, this and the small beam part are provided within the wall thickness of the slab, and the beam does not protrude from the bottom surface of the slab at all. Or it has a structure that only slightly protrudes.

On the other hand, conventional composite slabs, which have a composite structure by integrating precast members and cast-in-place concrete, consist of precast concrete 1 or steel beams stretched between columns, and precast boards that also serve as formwork between the beams. It is known that they are integrated by laying them side by side and pouring cast-in-place concrete onto the beams and precast boards.

(Problem to be solved by the invention) In the conventional PC slab described above, in the case of disasters such as earthquakes, unbonded type 9
Assuming that the prestress is released for 0g4 material,
This has the problem of being uneconomical as it requires the use of a large amount of concrete reinforcing material that is not normally required.
In addition, since prestress is applied continuously to the large beam between columns over the entire area including several columns using the boss tensioning method, deformation in the tensile direction (axial deformation) becomes large, causing large amounts of damage to the columns and walls. There was a problem in that statically constant secondary stress was generated.

In addition, the above-mentioned conventional base slab is made by integrating the precast board and the cast-in-place concrete placed on the top surface, so that the whole can be treated as a single floor slab, and the girders and As for the small beams, we use precast concrete or steel beams that are manufactured to have enough strength to withstand the beams themselves, and the beams are large and unsuitable for thin, lightweight floors with large spans. there were.

The present invention aims to provide a composite PC slab that can solve the problems of the conventional slabs as described above.

(Means for Solving the Problems) A feature of the composite PC slab of the present invention that achieves the above-mentioned objects is that it is made of precast concrete and is prestressed by embedding bond type PC steel in the longitudinal direction. A flat beam is spanned between the columns, and between the flat beams, a small beam made of precast concrete, which is also prestressed by burying bond type PCG4 material in the longitudinal direction, is spanned, and a mold is placed between the small beams. Precast boards that also serve as frames are lined up and laid over, and a floor slab made of cast-in-place concrete is formed over the entire upper surface of the flat beams for the large and small beams and the precast boards. The reason is that prestress is applied by the prestressing steel material.

(Function) The composite PC slab of the present invention has a structure in which the major beam portion and the minor beam portion are bottomed by precast flat beams and cast-in-place concrete.

The floor slab section will be an addition to the base made of precast boards and cast-in-place concrete.

In addition, all flat beams are bond type PCs.
Because the steel material is prestressed, the prestress will not be released even in the event of an earthquake or other disaster.
Therefore, there is no need to put in a lot of concrete reinforcement material only for safety in the event of a disaster. In addition, the entire floor slab is prestressed with unbonded PCa material,
It has a long span, is thin, and is lightweight.

(Example) Next, an example of the present invention will be described with reference to FIGS. 1 to 6.

In the figure, 1 is a column made of precast or cast-in-place concrete, 2 is a large beam between the columns, 3 is a small beam between the large beams 2, and 4 is a floor slab.

The girder section 2 is composed of a girder flat beam 5 and a cast-in-place concrete section 6 that is cast integrally with the floor slab section 4. The flat beam 5 is made of precast concrete and has a bonded type p facing in the internal longitudinal direction.
Prestress is applied by c@materials 7, 7, . . . . This PC steel material 7 may be attached directly to the concrete and prestressed using a pretensioning method, or it may be inserted into a sheath and prestressed using a posttensioning method, and the prestressed material may be applied by a cloud. It may be fixed indirectly to the concrete, and the necessary reinforcing reinforcing bars are buried in the flat beam 5 for Daito, and hoop bars 8, 8, etc. are installed on the top surface. A large number of bars are protruded at regular intervals, and the main reinforcing bars 9 are inserted inside the bars and fixed to each other.

The small beam part 3 is formed at the bottom by a small beam 10 spanning between the large flat beams 5.5 and cast-in-place concrete 6 for a floor slab cast on the upper surface of the small beam 10. The beam 10 for small beams is similar to the flat beam 5 for large beams,
A bond type PC steel material 7 is buried in the longitudinal direction and prestressed, and a hoop line 8 is formed on the top surface.
, 8... are protruded in large numbers at regular intervals.

Moreover, an erection protrusion 10a is integrally protruded from the upper side of the tip of the small beam 10, and this protrusion 10a is loaded onto the edge of the large beam flat beam 5. Also,
On both sides of the flat beam 5 for the main beam, beams 10 for small beams 10° 10 are installed in the direction of extension of each other, and the beams 10 for small beams 10 and 10 whose end surfaces face each other are straddled in a direction in which they are pulled into each other. Partial prestressing is applied using PC@C soil material for secondary tensioning.

This secondary tension is applied to the small beam 10 as shown in FIG.
．． Protruding parts 10b and 1ob are integrally provided on both sides of 10, and a straight PC@C soil material may be passed through these parts and tensioned.Also, as shown in Fig. 6, from the top An arc-shaped PC steel material 11 inserted through the end surface may be tension-fixed on the upper surface.

In this way, by applying secondary tension to both ends of the small beam 10.10 and straddling the large flat beam 5, the small beam 3 is continuous over the entire floor slab.
As a result, the upward stress on the girder flat beam 5 is alleviated.

The floor slab section 4 is constituted by a precast board 12 and cast-in-place concrete 6 which are arranged and stretched between small beams 10 and 10. The precast board 12 is made of concrete, has a substantially W-shaped cross section, and has a groove 12a on the top surface extending in the longitudinal direction.

12a is used, and the concave eraser 12a is used.
A bond-type PCa material 13 is buried in a and prestressed. An unbonded cable 13, which is an unbonded type PC steel material, is inserted into the groove 12a of the precast board 12 so as to extend across the plurality of precast boards 12 and continuously over the entire width of the floor slab. As shown in FIG. 4, this unbonded cable 13 is connected to an anchor 1 provided at the center of the precast board 12 so that the tension exerts a lifting force on the center of the precast board 12.
4 is fixed at a lower position, and positioned at a higher position on the small beam 10.

In addition, the cast-in-place concrete 6 has hoop bars 8.
Reinforcing reinforcing bars (not shown) are arranged continuously over the entire upper surface of the precast board 12, and are embedded and cast over the entire floor slab. The large beam part 2, the small beam part 3, and the floor slab part 4 are integrated by this cast-in-place concrete 6, thereby forming a mutually integrated composite beam and composite floor. By fixing each unbonded cable 13 under tension at both ends of the floor slab, the entire floor slab is made of PC411, and a lifting force is applied between the beams of the floor slab section 4.

(Effects of the Invention) As described above, the composite PC slab of the present invention uses precast concrete beams for large beams and small beams, which are prestressed by bond type PC steel, By constructing a composite beam with these and cast-in-place concrete, even though it is a cast-in-place PC slab, it is possible to include PC@ materials in the strength calculation during design, and unlike conventional methods, a large amount of reinforcing material can be used in the event of a disaster. In addition, since precast members are stretched across the floor slab section, the time and effort of assembling formwork is eliminated, making it possible to obtain highly economical PC slabs. It is.

Further, in the present invention, since the entire structure is made of PCI, a thin, light and long-span slab can be obtained.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a plan view showing the arrangement of structural members, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. Figure 4 is a cross-sectional view taken along line C-C, Figure 5 is a plan view of an example of the construction part of the beam for small beams, Figure 6 is a cross-sectional view of another example, Figures 7 and 4 are FIG. 8 is a plan view and a sectional view of a conventional example. 1... Column, 2... Large beam, 3...
... Small beam section, 4 ... Floor slab section, 5 ... Flat beam, 6 ... Cast-in-place concrete, 7.11 ... PC @ material , 8... Hoop line, 10... Beam for small beam, 10a...
・Protrusion, 10b...Protrusion, 12...
...Precast board, 12a... Concave, 13.
...Unbonded cable.

Claims (1)

[Claims] A precast concrete flat beam for the girder section, which is prestressed by burying bond type PC steel material in the longitudinal direction, is spanned between the columns, and bond type PC steel material is also buried in the longitudinal direction between the flat beams. A precast concrete beam for small beams which has been prestressed is stretched between the small beams, and precast boards that also serve as formwork are lined up and spanned between the small beams, and the entire upper surface of the flat beams for the large and small beams and the precast boards are laid out between the small beams. A synthetic PC slab is formed by forming a floor slab made of cast-in-place concrete integrated with these, and applying prestress to the floor slab with unbonded type PC steel material.