JPH0420053B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reinforcing member for controlling the width of cracks in a concrete plate, such as a concrete wall, or the corner of an opening thereof, and a method for reinforcing the same.

Generally, stress is concentrated at the opening corners of a concrete plate due to drying shrinkage of the concrete, and cracks are likely to occur. In order to suppress the occurrence of such cracks and the crack width as small as possible, conventionally, as shown in Fig. 1, vertical, horizontal, and diagonal wire meshes a and b are embedded in the opening corners of concrete plates.
There was one that placed oblique muscle c.

However, even with the above-mentioned reinforcement arrangement, cracks still occur at the corners of openings, and the width of the cracks is quite large, resulting in frequent problems such as water leakage and damaging the appearance of the building in the case of external walls. However, there were also problems with the inner walls, such as reduced durability due to corrosion of reinforcing bars.

The present invention has been made in view of the problems of the prior art described above, and includes a reinforcing member for a concrete plate that can easily and inexpensively suppress the width of cracks in the corner of the opening of the concrete plate to below an allowable value. The purpose is to provide a reinforcement method.

That is, what forms the basis of the present invention is a reinforcing member of a concrete plate in which at least one loop-shaped part is provided in the middle of a steel bar and folded parts are provided at both ends;
A method for reinforcing a concrete wall includes arranging the reinforcing member diagonally at the corner of an opening of a concrete plate.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIGS. 2A to 2C illustrate the basic principle of the present invention. That is, regarding the control of the crack width in concrete mentioned above, although some estimation formulas have been proposed for short-term reinforcing steel stress, although they are extremely insufficient,
In the long term, this remains an unknown issue. For example, even if a 10m/m round steel e is buried in concrete f with a length of 40d (40cm) as shown in A, its ends A,
Since pull-out occurs at C, the middle part B changes as shown in B (it does not pull out under short-term load), and each part A to C
As shown in Figure C, the adhesion deterioration progresses from the load end to the inside. In order to prevent the above-mentioned pull-out (slipping between concrete and reinforcing bars), even if a round steel e is folded back at both ends and provided with hooks, the length is 40 mm.
cm, it was found that it was not effective in suppressing the crack width due to the elongation of the round steel e itself.

As a result of extensive research based on this knowledge, the present invention has been developed as follows: L=E・S/σ...( 1) However, σ: Reinforcement stress Kg/cm ² S: Permissible crack width cm L: Length between reinforcing bar hooks cm E: 2.1×10 ⁶ Kg/cm ² This was done after discovering that the crack width could be controlled to below an allowable value by arranging and reinforcing the steel.

The reinforcing member 1 shown in FIG.
It has been established. The length L between the folded portion 4 and the center of the loop 3 takes a value obtained by substituting the desired σ and S into equation (1). For example, assuming σ = 2000 Kg/cm ² constant, S = 0.02, If it is 0.01cm, L will be 21cm and 10.5cm, respectively. This reinforcing member 1 can be easily manufactured by bending a bar-shaped round steel 2. This round steel 2 may be a general reinforcing bar, such as a steel bar of different diameters. Further, the loop-shaped portion 3 is not limited to a circular shape as shown in the figure, but may be triangular or triangular.
It can be any closed curve such as a rectangle or an ellipse.

The reinforcing member 5 shown in FIG.
The loop-shaped portions 3, 3 are connected at a predetermined interval. The lengths between the loop portions 3 and 3 and between the loop portion 3 and the folded portion 4 are equal to L as in the case of FIG. 3. This loop-shaped part 3 can be used for a blank board such as an earthquake-resistant board by linking three or more arbitrary numbers and making it into a long shape like the reinforcing member 6 shown in FIG. can.

The reinforcing member 7 shown in FIG.
The loop-shaped parts 8, 8 are intersected and provided in a bowknot shape, and both arm parts 2a, 2a of the round steel 2 are
On the opposite side of the arm 2a, the arm 2a is provided perpendicularly to the shape of the opening corner of the concrete plate, and a folded part 3 is further provided at the tip of the arm 2a. and,
The length of the common base line 8a of the two loop-shaped parts 8, 8 and the length between the opposing line 8b of the loop-shaped part 8 continuous to the arm part 2a and the opposite side are the length of the loop-shaped part 8 and the folded part 3, respectively. The above (1) between the centers O and O of
Let the length L satisfy the formula.

The reinforcing member 9 shown in FIG. 7 does not have a loop-shaped part in the middle of the round steel 2, but has a loop-shaped part 10 by turning both ends thereof, and has a folded hook part 1 formed at the tip of the loop-shaped part 10.
1 is hung on a round steel 2 to prevent the loop-shaped part 10 from expanding due to stress, and the length between the centers O and O of the loop-shaped part 10 at both ends is the same as above (1 ) as L that satisfies the equation. In addition, also in the case of the above-mentioned reinforcing members 1, 5, 6, and 7, a loop-shaped part 10 can be provided instead of the hook-shaped folded part 4.

The reinforcing member 9' shown in FIG. 7A also does not have a loop-shaped part in the middle of the round steel 2, but has both ends folded back in opposite directions, and the folded parts 10' are tied together in a so-called figure 8 shape. The length between the centers O and O of the folded portion 10' is set to L. Incidentally, it is preferable that the thickness of the intermediate intersection of the reinforcing member 9' be made as thin as possible by pressing or crushing the round bars 2 together.

A reinforcing member 9'' shown in FIG. 7B is made by folding both ends of a round bar 2 in the same direction and tying the folded parts 10'' together to form two bar bars 2 parallel to each other without crossing each other. .

Next, a method for reinforcing concrete plates will be explained.

In FIG. 8, 12 is a concrete plate in which an opening 13 is formed. Reinforcement bars 1 are placed in the concrete plate 12 vertically and horizontally along the edge of the opening 13.
4 are arranged and intersect at the corner 12a. In the illustrated example, the reinforcing members 1, 5, 7, and 9 are arranged in the corner 12a of the opening 13 sequentially clockwise from the upper left corner. These reinforcing members are
When arranging the reinforcing bars 14, the reinforcing bars 14 can be arranged by a simple operation of fixing them with wire or the like so that they are positioned diagonally to the corner 12a as shown in the figure, and pouring concrete. After the concrete hardens and reaches the required compressive strength, the adhesive force between the concrete and the reinforcing member is strong due to the existence of the loop portion 3, folded portion 4, etc. in each case, as shown in Fig. 2. Since there are almost no changes in slip and creep as shown in Figure 3, the width of cracks Q in concrete that are likely to occur at corners can be suppressed to below a desired allowable value.

In particular, when the bowknot-shaped reinforcing member 7 is arranged as in the lower right corner 12a, the arm part 2a of length L is parallel to the edge of the opening 13 along with the two loop parts 8, 8. Because of this location, the width of cracks that occur in this area can also be controlled.

Fig. 8A shows a state in which the reinforcing member 9' shown in Fig. 7A is diagonally arranged at the corner 12a of the opening 13 of the concrete plate 12, thereby effectively controlling the width of the crack Q. be able to.

FIG. 9 shows a long reinforcing member 6 installed in parallel with a blank concrete board 15 such as an earthquake-resistant board.
In this example, the crack width can be controlled in the same way as above.

Since the present invention is as explained above, it has the following advantages.

1. The crack width, which was difficult to control in the past, can be increased to a desired width.

2. Water leakage and appearance problems caused by widening of cracks are eliminated.

3. The reinforcing member can be easily manufactured from bar-shaped round steel by bending, and the reinforcing work is easy, so the cost is extremely low.

4. Construction management is easy and reliable results can be obtained.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional example, Fig. 2 A to C are explanatory diagrams respectively showing the principle of the present invention, and Figs. 3 to 7
The figures are respectively a front view of the reinforcing member of the present invention and No. 7A.
7B are front views showing another embodiment of the reinforcing member shown in FIG. 7, and FIGS. 8, 8A, and 9 are explanatory views of the method of the present invention, respectively. 1, 5, 6, 7, 9... Reinforcement member, 2... Round steel,
3, 8, 10... loop-shaped part, 4... folded part.

Claims (1)

[Scope of Claims] 1 At least one loop-shaped part is provided in the middle of the steel bar, and folded parts are provided at both ends, and the length L of these loop-shaped parts and the folded part, or the length L between each loop-shaped part is The length L is expressed by the formula L=E・S/σ, where E: 2.1×10 ⁶ Kg/cm ² S: Allowable crack width cm σ: Reinforcement stress Kg/cm ² Reinforcing member for concrete plate. 2. Two loop-shaped parts are provided in the middle of the steel bar in a bow-like shape, and both arm parts are provided orthogonally on the opposite side of the loop-shaped part, and a folded part is provided at the tip of the arm part, The length L of the common base line of the above two loop-shaped parts and the length L between the opposing lines of the loop-shaped part continuous on the arm part and the opposite side are calculated by the formula L=E・S/σ However, E: 2.1×10 ⁶ Kg/cm ² S: Allowable crack width cm σ: Reinforcement stress Kg/cm ² A reinforcing member for a concrete plate characterized by being formed to satisfy Kg/cm 2 . 3 At least one loop-shaped part is provided in the middle of the steel bar, and folded parts are provided at both ends, and the length L of these loop-shaped parts and the folded part, or the length L between each loop-shaped part, is calculated by the following formula: L=E・S/σ However, E: 2.1×10 ⁶ Kg/cm ² S: Allowable crack width cm σ: Reinforcement stress Kg/cm ² : The formed reinforcing member should be placed at the opening corner of the concrete plate. A method of reinforcing concrete plates characterized by placing them diagonally in the sections. 4. Two loop-shaped parts are provided in the middle of the steel bar so as to intersect in a bow-like shape, and both arm parts are provided orthogonally on the opposite side of the loop-shaped part, and a folded part is provided at the tip of the arm part, The length L of the common base line of the above two loop-shaped parts and the length L between the opposing lines of the loop-shaped part continuous on the arm part and the opposite side are calculated by the formula L=E・S/σ However, E: 2.1×10 ⁶ Kg/cm ² S: Allowable crack width cm σ: Reinforcement stress Kg/cm ² A concrete plate characterized in that the formed reinforcing member is placed at the opening corner of the concrete plate. reinforcement method. 5 At least one loop-shaped part is provided in the middle of the steel bar, and folded parts are provided at both ends, and the length L of these loop-shaped parts and the folded part, or the length L between each loop-shaped part, is calculated by the following formula: L=E・S/σ However, E: 2.1×10 ⁶ Kg/cm ² S: Allowable crack width cm σ: Reinforcement stress Kg/cm ² To satisfy: Place the formed reinforcing member inside the concrete plate. , a method for reinforcing concrete plates, characterized in that they are arranged along the longitudinal direction.