JPH0369748A - Concrete slab - Google Patents

Abstract

PURPOSE:To obtain highly stabilized structure by making precast flat beams spanning columns integral with floor board made by casting concrete thereon in site, and by giving prestress thereto with prestressing steels for secondary stress inserted between end members. CONSTITUTION:Steels 15 for bond prestressing are inserted into a flat beam 14 for a girder, and tie hoops 16 and main reinforcements 17 are arranged above the flat beam. A prestressing steel 21 for secondary stress is inserted in continuous circular arc shape spanning the flat beams 14 for the girders, and is anchored with stress to pressure-bearing boards 22. Then a plurality of a flat beams 14a for binders are installed between the flat beams 14 for the girders and prestress is given thereto with prestressing steels 15a. Precast boards 23 are then installed side by side between the flat beams 14a for the binders and unbond cables 24 are installed thereon. Thereby a flat slab of thin make having high durability can be obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a floor slab formed of cast-in-place concrete,
Unbonded type PC with unbonded cable etc. inside
Concerning a concrete slab that is prestressed by using @ material to span the entire area of the floor slab.

(Prior Art) Conventionally, as shown in FIGS. 8 and 9, a flat slab is supported by columns 1, and the entire floor slab 2 is formed into an integral bottom with cast-in-place concrete. A beam part 3 that does not protrude or projects from the lower surface of the floor slab 2 is integrally formed, and the strand is slidably inserted into the synthetic resin sheath over the entire area of the floor slab 2 including this beam part 3. A so-called unbonded cable 4 is buried to apply prestress.

In general, when building horizontally with prestressed concrete supplements using unbonded type PC steel materials such as unbonded concrete steel, it is important to consider The major structural parts of the
The strength of steel was not included, and instead a large amount of reinforcing structural materials such as reinforcing bars were used.

(Problems to be Solved by the Invention) Such conventional flat slabs are constructed on the assumption that prestress due to unbonded PC steel materials will be removed in the event of a disaster such as an earthquake, especially in the parts that constitute the girders between the columns. C:! There is a problem that it is uneconomical because a large amount of unnecessary concrete reinforcement structural material must be used, and the post-tensioning method is also used to continuously extend the entire area including several columns to the large beam between the columns. In order to apply prestress, deformation in the tension direction due to tension (
There was a problem in that the axial deformation (axial deformation) became large and a large unstatic secondary stress was generated in the columns and walls.

In view of the above-mentioned conventional problems, the present invention reduces the amount of concrete reinforcing structural material used, prevents large unsteady constant secondary stress from occurring in the columns and walls between the columns, and increases the distance between the columns. The purpose is to provide concrete slabs that can be removed.

(Means for Solving the Problems) A feature of the present invention for solving the above-mentioned conventional problems and distantly achieving the intended purpose is to use a bond type PC in the longitudinal direction.
A precast flat beam prestressed by steel material or a secondary tension PC that is stretched between columns, continuous between the ends of longitudinally adjacent flat beams on the column, and inserted so as to straddle the columns. Fress 1-less is applied to parts of steel materials in the direction of mutual attraction, and a floor slab made of cast-in-place concrete is integrally formed on the flat beam, and an unbonded type P is applied to the entire floor slab.
This is due to the fact that prestressing was applied using C steel material.

(Function) This concrete slab is made up of a precast flat beam that spans between columns and cast-in-place concrete for the floor slab that is cast on top of it, and the precast part and cast-in-place concrete part are combined. The girder section is made up of In addition, this girder part is partially prestressed between the ends of the precast flat beam by using PC steel material for secondary tension, so it is similar to pcW4 where continuous prestress is applied to the whole. It is possible to form a large beam with a long span, and since this secondary tension is partially arranged to straddle the columns, the unsteady secondary stress due to tension is small, resulting in a stable structure.

(Example) Next, an example of the present invention will be described with reference to FIGS. 1 to 7.

In the figure, 10 is a floor slab, 11 is a column, and 12 is a girder part that is integrated with the floor slab.

The pillars 11 are erected from precast or cast-in-place concrete, and a flange-shaped deck support protrusion 13 is integrally protruded from the deck support position.

The girder portion 12 is constructed by integrally synthesizing a precast concrete girder flat beam 14 and cast-in-place concrete 10a constituting the floor slab 10. The flat beam 14 for the girder is made of bond type PE in the longitudinal direction.
A material 15 is inserted through it, and a breech is provided by the grating tension system, and a hoop line 1 is provided on the upper surface.
6.16... is protruded in the width direction, and a T-strip 17 is inserted through the inside of the top. The ends of this flat beam 14 are integrally formed with a recess 18 into which the column 11 fits, and horizontal protrusions 19 and 1 on both sides thereof.
The end faces of the pillars 9 are butted against each other on the floor slab support protrusion 13 of the pillar 11.

In addition, arc-shaped PC@ material insertion holes 20 are formed in the end faces of the horizontal protrusions 19 that abut against each other and open in the upper surface of the flat beam 14 for girder. A continuous arc-shaped secondary tensioning PC is placed in the PC steel material insertion hole 20 and spans both the girder flat beams 14.
The @ material 21 is inserted, and both ends are supported by the bearing pressure plate 22 of the opening on the front surface side of the flat beam of the PC steel material insertion hole 20 and fixed under tension, giving a partial prestress between the ends.

Note that this PC@ material 21 is of a bond type, and after tensioning, Cement 1~ system cloud is injected into the PCC steel material through hole 20 and solidified, and the PCj11 material 21 and the flat beam 14 for the girder are bonded. It is integrated.

In this way, a plurality of small beam flat beams 14a, 14a, . . . are spanned in parallel with each other at intervals between the large beam flat beams 14, which are stretched parallel to each other. This flat beam 14a for small beams 14a is also prestressed in the longitudinal direction by a bond type 90g4 material 15a, and a hoop reinforcement 16a is protruded from the upper surface, and a main reinforcement 17a is inserted inside the hoop reinforcement 16a. A small beam portion 12a is formed by integrating with the cast-in-place concrete 10a.

In this way, precast boards 23, 23, which also serve as formwork and have a W-shaped cross section, are arranged in parallel and span between the flat beams 14a for small beams, which are stretched in parallel. The unbonded cable 24 is passed over the flat beam 14a for a small beam in the groove on the upper surface, and is disposed continuously over the entire area of the floor slab 10, and the flat beam for a small beam described above is placed on the precast board 23. 14a
Reinforcing reinforcing bars (not shown) are arranged integrally with the hoop reinforcements 16a and main reinforcements 17a that protrude upward, and cast-in-place concrete 10a is integrally placed on the flat beam 14a for the small beam, and the precast parts and The composite floor slab 10 is being molded.

In the above-mentioned embodiment, the both ends of the arc-shaped PCM material 21 are tension-fixed to the upper surfaces of the flat beams 14, 14, but as shown in FIG. A straight prestressing PC steel material 21a for secondary tensioning may be inserted into the overhanging portions formed on both end surfaces of the flat beam for the girder, and prestress may be applied partially. 14, 14 may be formed with a thick inner part on the lower surface, and a prestress may be applied to this by applying PCJl material for secondary tension.Furthermore, as shown in Fig. After forming the floor slab 10, this floor slab lO and the flat beam 14 for both girders are
．． PC @ material 21 for arc-shaped secondary tension across 14
It is also possible to fix both ends of the flat beam 14 on the pillar 11 with the ends separated from each other on the pillar 11. Pillar 1
It is also possible to integrally place a floor slab 10 made of poured concrete on site 1.

In addition, in the above-mentioned embodiment, the W-shaped precast board 23 is used, but instead of using this, a formwork is constructed by supporting it on shoring, and cast-in-place concrete is poured on top of it. The floor slab 10 may be formed integrally with the flat beam for the girder.

In the flat slab constructed as described above, if prestress is not applied between the ends of the flat beam 14 for the main beam by the secondary tensioning PC steel material 21, a large upward stress will be generated on the pillar 11 in the large beam part. However, P for secondary tension
F by C steel material 21.

By applying the rest stress, the upward stress on the column 11 is relaxed, stress concentration no longer occurs, and a thin and long-span girder can be obtained.

(Effects of the Invention) As described above, in the concrete slab of the present invention, a flat beam and cast-in-place floor plate concrete are combined to form a girder section, and the flat beam is pre-assembled with bond type PCu material. Because stress is applied, the strength of the prestressed steel can be included in the strength calculation during design, which eliminates the need to use large amounts of concrete reinforcement only for disaster situations, improving economic efficiency. It is.

The present invention also allows the flat beam to be turned into a flat beam itself.

Recast prestressed concrete structure and none,
In addition, by applying prestress in a direction that partially draws the two adjacent ends together, and applying a --like prestress to the whole, axial deformation due to tension after erection on the column is prevented. This results in a highly stable S-type structure with low unsteady constant secondary stress.Furthermore, the upward stress at the top of the column is reduced due to the secondary tension, resulting in a thin and high-yield flat slab. There is.

[Brief explanation of drawings]

FIG. 1 is a plan view of the arrangement of structural members in the first embodiment of the present invention, and FIG. 2 is A-AiI! in FIG. 3 is a sectional view taken along the line C-C, FIG. 4 is a sectional view taken along the line C-C, and 5th
The figure is a plan view of the cross section of the flat beam for girders, Figure 6 is a cross-sectional view of the flat beam for girder of the second embodiment in the secondary tension state, and Figure 7 is the flat beam for girder of the third embodiment. 8 is a plan view of a conventional flat slab, and FIG. 9 is a longitudinal sectional view thereof. 10...Floor slab, 11...Column, 12...
...Large beam part, 12a...Small beam part, 13...
... Support protrusion, 14 ... Flat beam for large beam, 14a ... Flat beam for small beam, 14
b... Thick wall part, 15, 21, 21 a, 2 IC-=-PC steel material,
16.16a...Hoop bar, 17.17a...Main bar, 18...Concavity, 19...Horizontal protrusion, 20... Insertion hole, 22... Bearing plate, 23... Precast plate, 24... Unbonded cable.

Claims (1)

[Claims] A precast flat beam prestressed by bond type PC steel in the longitudinal direction is spanned between the columns, and the end portions of the flat beams adjacent in the longitudinal direction are continuous on the column so as to straddle the columns. A prestress is partially applied in the direction of drawing each other using secondary tensile prestressed steel inserted through the flat beam, and a floor slab made of cast-in-place concrete is integrally formed on the flat beam, and an unbonded type is applied to the entire slab. A concrete slab that is prestressed using prestressed steel.