JPS6065854A - Concrete slab and its construction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to concrete slabs and methods of construction thereof.

Generally, when a concrete slab 2 is constructed on top of multiple strips of @1 as shown in Figure 1, when the stress applied to this concrete slab 2 is measured, each stress is shown in Figure 1 (B'). The upward stress is maximum in the prefecture part, and the relationship between the maximum value a of the upward stress and the maximum value of the downward stress is a>b.

For this reason, cracks often occur in the concrete slab 2 at a portion corresponding to the beam 1. In order to prevent this, the thickness of the concrete slab 2 has conventionally been increased, but such a solution has the drawback of significantly increasing costs.

An object of the present invention is to provide a concrete slab having a structure that suppresses increases in cost and prevents cracks, and a method for constructing the same.

The 11th invention of the present application provides that, in a concrete slab formed by being supported by a plurality of beams, in a cast-in-place concrete layer constituting the concrete slab, a portion corresponding to each prefecture is provided at both ends of the concrete slab. The concrete is characterized by having tension members built into it in a tensioned state so that each prefecture is placed in the center and extending over both sides, thereby imparting partial prestress to the cast-in-place concrete layer.

The second invention of the present application provides that when constructing a concrete slab supported by a plurality of beams, before pouring the cast-in-place concrete layer, only the portions corresponding to the respective prefectures are straddled to the left and right. The tension members are placed in parallel, and both ends of the tension members are supported by reaction jigs straddled on both sides of each beam to apply tension to each tension member. The method is characterized in that a cast-in-place concrete layer is poured by embedding the cast-in-place concrete layer, and after the concrete hardens, the reaction jig is removed to partially apply prestress to the cast-in-place concrete layer. .

The third invention of the present application is to erect a precast plate such as a precast concrete plate or a deck plate with both ends supported between the beams when constructing a concrete slab supported by a plurality of beams. Tensions are placed across the precast plates on both sides of the beam only in the portion corresponding to each prefecture, and both ends of each tendon are fixed to the precast plates on each side using a reaction jig. A tension force is applied to each of the tendons in a supported state, and a cast-in-place concrete layer is poured onto the precast board so that these tendons are embedded, and after the cast-in-place concrete layer has hardened, each of the above-mentioned The tendons are separated from the reaction jig and placed in the cast-in-place concrete layer.

The fourth invention of the present application provides that, when constructing a concrete slab supported by a plurality of beams, before pouring the cast-in-place concrete layer, the parts corresponding to the respective prefectures are straddled on both sides. Place the tension materials on each side,
Concreting the cast-in-place concrete layer by embedding each of the tendons, and after the concrete hardens, tensioning each of the tendons to partially apply prestress to the cast-in-place concrete layers 1 to 1. It is characterized by:

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows an embodiment of concrete 1 to slab 2 according to the present invention. The concrete slab 2 of this embodiment is entirely composed of a cast-in-place concrete layer, and tensile materials such as prestressed steel are straddled on the left and right only in the portions of the layer corresponding to each prefecture 1. 3 is built in tension and reinforced.

In this way, if the concrete slab 2 is reinforced with the tension material 3 at the 6-beam 1 part to create a partially prestressed concrete structure, the upward stress acting on the concrete slab 2 at the 6-beam 1 part can be alleviated, and the concrete slab 2
It is possible to prevent cracks from forming in the connecting portion with the beam 1.

FIG. 3 shows an example of the first construction method of the concrete slab 2 according to the present invention. As shown in the figure, the floor formwork 4 and beam formwork 5 are supported by supports 6, slab reinforcement 7 is placed on the floor formwork 4, and beam reinforcement 8 is placed in the beam formwork 5. Further, tension members 3 such as PCCuO are provided in the portions corresponding to the six beams 1, and these tension members 3 are tensioned by supporting both ends with reaction force jigs 9.

The reaction jig 9 may be of the type that applies tension to the tendon material 3 by extending its entire length in the longitudinal direction, for example, in the relationship between a screw and a nut, or it may be of the type that does not change in length and may be Use a type that applies tension using jacks or screws. Further, the tension material 3 is placed in the groove at both ends of the reaction force jig 9, and a stopper member is used to prevent the material from being pulled out in the longitudinal direction, and tension is applied. Furthermore, the gripping portions at both ends of the reaction force jig 9 are covered with foam material or the like to prevent concrete from entering. In this state, concrete is poured on the floor formwork 4 and inside the beam formwork 5 to form the concrete slab 2 and the beam 1. After the concrete 1- hardens, the reaction jig 9 is removed, and the recesses formed at both ends of the tendon 3 are filled with concrete to flatten the concrete 1-slab 2. In addition, each formwork 4
, 5 will also be removed.

FIG. 4 shows another example of the first construction method.

In this embodiment, a reaction jig 9 is arranged below the formworks 4 and 5 to tension the tension material 3.

FIG. 5 shows still another example of the first IS construction method. In this embodiment, a precast plate 1o such as a precast concrete plate or a deck plate is erected with both ends supported by a beam 1 made of a steel frame, and slab reinforcement 7 is provided on the precast plate 10, and six beams 1 are supported. A tensioning member 3 is disposed only on the left and right precast plates 10 at only that part, and is supported by a reaction jig 9 and tensioned. Concrete is cast in place on the precast board 10 as a formwork in a bent state, and slab reinforcement 7 and tension material 3 are embedded in this cast in place concrete layer 11.

As a result, a composite concrete slab 2 is formed by the precast plate 1o and the cast-in-place concrete layer 11.

After the cast-in-place concrete layer 11 hardens, the reaction force jig 9 is removed, and the four parts after its removal are as follows.

Fill with concrete and level it.

FIG. 6 shows an example of the second construction method of the concrete slab 2 according to the present invention.

In this embodiment, a precast plate 10 made of a precast concrete plate is supported at both ends by a beam 1 made of a steel frame.
erect. 6 Tension members 3 are provided only in the portions corresponding to the beams 1 so as to straddle the left and right precast boards 1o, and both ends of these tension members 3 are connected to the precast boards 1 on each side.
o is supported by a fixed reaction force jig 13 fixed with bolts 12 to apply tension. At this time, a variable-length reaction force jig 14 such as a turnbuckle is interposed between the ends of adjacent precast plates 10 on the beam 1 to prevent the precast plates 10 on both sides from coming closer together due to the tension of the tension material 3. Let's prevent it.

The location of each reaction jig 13 is wrapped with concrete removal material such as foam material to prevent it from being buried in concrete.

In this state, concrete is cast in place using the precast board 10 as a formwork, and the tension material 3 and the reaction force jig 14 are embedded in this cast in place concrete layer 11. Concrete removal material and reaction jig 1 after concrete hardens
3 was removed and concrete 16 was placed in the hole formed in its place.
Fill it and level it. The reaction jig 14 is made of concrete.
1 - Bury it inside.

FIG. 7 shows another example of the second horizontal construction method for concrete slabs according to the present invention. In this embodiment, an embedded metal fitting 17 is provided in advance at the end of the precast plate 10 made of a precast concrete plate located on the beam 1, and this embedded metal fitting 17 is fixed with a welding part 18, so that each precast plate 10@beam 1 Fixed to. Further, the tensioning material 3, which is disposed across the left and right precast boards 10 only in the portion corresponding to the six beams 1, is tensioned by a tensioning means such as a jack, and the bolts 12 are attached to each precast board 10.
It is fixedly supported by a fixed reaction force jig 13 fixed at . The area around the reaction jig 13 is wrapped with a concrete removing material such as foam material to prevent it from being buried in concrete. In this state, concrete is cast in place using the precast board 10 as a formwork, and the tension material 3 is embedded in the cast in place concrete layer 11. After the concrete has hardened, the concrete removal material 15 is removed, the tension material 3 is cut and planted from the reaction jig 13, and the holes made there are filled with concrete 16 and flattened.

FIG. 8 shows the second ta of the concrete slab according to the present invention.
This shows another example of the method. This embodiment is almost the same as the embodiment shown in FIG. 7, except that a deck plate is used as the precast board 10. Furthermore, due to the use of the deck plate, the reaction force jig 13 is fixed to the precast plate 10 by welding, and the reaction jig 13 is fixed to the precast plate 10 by welding.
is directly fixed to the beam 1 with a welded portion 18.

FIG. 9 shows an example of a third method for constructing a concrete slab according to the present invention. In this example, the sheath 1
A tension member 3 having a tension member 9 is disposed only in a portion corresponding to the beam 1 so as to straddle both sides of the beam 1, and a fixing plate 20 is attached to one end of the tension member 3, and a concrete removal material 15 such as a foam material is attached to the other end. to prevent it from being buried in concrete.

Concrete is cast in this state, and the sheath 19 and tendons 3 are embedded to form a concrete slab 2.

After the concrete has hardened, the concrete removal material 15 is removed, and the other end of the tension material 3 protruding into the recess is tensioned with a jack or the like. After that, concrete 16 is placed in the depression of concrete slab 2.
Fill it and level it.

FIG. 11 shows another example of the third trench construction method for concrete slabs according to the present invention. This example differs from the embodiment shown in FIG. 9 only in that the concrete slab 2 is formed of a precast board 10 and a cast-in-place concrete layer 11, and that the beam 1 is a steel frame.

FIG. 12 shows still another example of the third method of constructing a concrete slab according to the present invention.

This embodiment shows an example in which one end of the tendon 3 is fixed by protruding from the sheath 19 and attaching it to concrete without using the fixing plate 20. Other points are similar to the embodiment shown in FIG.

As explained above, in the concrete slab and its construction method according to the present invention, the parts corresponding to the beams are partially reinforced by applying prestress, so that the upward stress acting on the concrete slab in the six beam parts is reduced. This can prevent cracks from forming in the concrete slab at the 6-beam section.

Furthermore, in the present invention, instead of increasing the thickness of the concrete slab to reinforce it, we have adopted a tR construction in which it is partially reinforced with tendons, so we can implement reinforcement measures to prevent cracks without causing significant loss. can do.

[Brief explanation of drawings]

Fig. 1 (A>(B) is a cross-sectional view of a conventional concrete I-slab and its stress distribution; the second factor is a cross-sectional view of an embodiment of the concrete slab according to the present invention; Fig. 3) , 4th
5 and 5 show the first concrete slab according to the present invention.
6, 7 and 8 are sectional views showing three examples of the second manufacturing method of the concrete slab according to the present invention, and FIG. , FIG. 11 and FIG. 12 are cross-sectional views showing three examples of the third manufacturing method of a concrete slab according to the present invention, and FIG. 10 is an example of the fixing structure of the other end of the tendon in the third method. FIG. 1... Beam, 2... Concrete slab, 3... Tensile material, 4.5... Formwork, 6
...Sabo 1-17...Slab reinforcement,
8... Beam reinforcement, 9... Reaction jig, 10
... Slab bottom plate, 11 ... Cast-in-place concrete layer, 12 ... Bolts, 13 ...
・Reaction force jig, 14...Reaction force jig, 15...
... Concrete removal material, 16 ... Concrete, 17 ... Embedded hardware, 18 ... Welded part, 19 ... Sheath, 20 ...・Fixing plate, 21...Grip chip 17, 22
...Fixing plate. Patent applicant: Spuncrete Manufacturing Co., Ltd.

Claims (2)

[Claims] (1) In a concrete slab formed by being supported by multiple beams, in the cast-in-place concrete layer constituting the concrete slab, place the six beams in the center at both ends of each beam in the portion corresponding to the six beams. A concrete slab characterized by having tension members built in under tension across both sides to impart partial prestress to the cast-in-place concrete layer. (2) When constructing a concrete slab that is supported by multiple beams, before pouring the cast-in-place concrete layer, add tendons to the left and right only in the areas corresponding to the six beams. The ends of the tendons are supported by reaction jigs straddled on both sides of each beam to apply tension to each tendon, and then these tendons are buried in place. Concrete 1 - A method for constructing a slab, characterized in that a poured concrete layer is poured, the reaction jig is removed after the concrete has hardened, and prestress is partially applied to the cast-in-place concrete layer. . ■ When constructing a concrete slab that is supported by multiple beams, a precast plate such as a precast concrete plate or deck plate is erected with both ends supported between the beams, and only the portions corresponding to the six beams are supported. Tensile members are placed across the precast boards on both sides of the beam, and each tension member is supported by a reaction jig with both ends of each tension member fixed to the precast boards on each side. One layer of cast-in-place concrete is placed on the precast board by imparting tension to the material and embedding the tendons, and after the cast-in-place concrete layer has hardened, each of the tendons is placed in the A method for constructing a concrete slab characterized by separating it from a force jig and partially applying prestress to a cast-in-place concrete layer. (4) When constructing a concrete slab supported by multiple beams, tension members are placed across both sides of the area corresponding to each prefecture before pouring the cast-in-place concrete layer. A cast-in-place concrete layer is poured by embedding each of the tendons, and after the concrete has hardened, each of the tendons is tensed to partially apply prestress to the cast-in-place concrete layer. 4 of concrete slabs characterized by
R construction method.