JPH0967945A - Shear reinforcement structure for building beams - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a shear reinforcement structure for a beam of a building, which can secure a shear reinforcement equivalent to that of the closed type without making it a closed type. A shear reinforcement structure for a building beam having a lower side surface and two side surfaces, the first FRP sheet (2
6) and a second FRP sheet (28). First
FRP sheet (26) is adhered to each of the two sides of the beam so that the fiber orientation extends in the axial direction of the beam (20). The second FRP sheet (28) is arranged between the lower side surface and the two side surfaces of the beam so that the direction of the fibers extends in the direction orthogonal to the axis of the beam, and the lower side surface and the first fiber-reinforced plastic sheet are provided. To glue.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shear reinforcement structure for a beam of a reinforced concrete structure, and more particularly to a reinforcement structure suitable for shear reinforcement of an existing structure beam.

[0002]

2. Description of the Related Art When a building made of reinforced concrete is newly constructed, in order to increase the shear strength of the beam by increasing the shear strength of the beam, as shown in FIG.
While arranging the shear reinforcing bar 14 so as to surround the
The two end portions 15 of the shear reinforcing bar 14 are bent inward and embedded in concrete to form a so-called closed type.

[0003]

Shear reinforcement of existing building beams cannot be achieved by the method using the shear reinforcement. Therefore, fiber reinforced plastic sheet (hereinafter FRP
Shear reinforcement of the beam can be considered by adhering the sheet) to the beam, but in order to perform the closed shear reinforcement similar to the above, a slit is made in the slab, that is, the floor, and the FRP sheet is attached to the beam. I have to wrap it. However, this method cuts the slab muscle,
Not only does the yield strength of the member decrease, but it is also disadvantageous in terms of cost.

The present invention provides a shear reinforcement structure for a building beam, which can secure the same shear reinforcement as that of the closed type without making the closed type.

[0005]

SUMMARY OF THE INVENTION The present invention is a beam beam shear reinforcement structure for a building having a lower side surface and two side surfaces, the structure including a first FRP sheet and a second FRP sheet. The first FRP sheet is adhered to each of the two side faces of the beam so that the fiber direction extends in the axial direction of the beam. On the other hand, in the second FRP sheet, the lower side surface and the first fiber-reinforced portion are laid between the lower side surface and the two side surfaces of the beam so that the fiber direction extends in the direction orthogonal to the axis of the beam. Adhere to a plastic sheet.

[0006]

[Operation and effect] On the side surface of the beam, while the fibers of the first FRP sheet extend substantially horizontally,
When the shear load is applied to the beam, the fibers of the FRP sheet of No. 2 are substantially perpendicular to each other and are orthogonal to each other, and cracks due to shear load appear on the side surface of the beam, and the direction is oblique. 1st FRP sheet and 2nd FRP
The sheet has great resistance to cracking and does not crack.

The first FRP sheet and the second FRP sheet prevent the occurrence of cracks on the side surface of the beam due to the shear load, and the beam is sheared and reinforced, thereby improving the shear strength of the beam.

The first FRP sheet is arranged so that its fibers extend in the axial direction of the beam and is bonded to the side surface of the beam, and then the second FRP sheet is extended in the direction in which its fibers are orthogonal to the axis of the beam. The lower side of the beam and the first FR
It is bonded to the P sheet. When stacking FRP sheets, the one that has the greatest effect on the load is the FRP sheet that directly adheres to the beam. Therefore, according to the present invention, the shear load applied to the beam at any position in the axial direction of the beam can be received by the entire first FRP sheet via the fiber extending in the axial direction. In this case, the second
The FRP sheet of 1 serves to reinforce the first FRP sheet. On the other hand, the first FRP sheet and the second FRP sheet
If the bonding order with the RP sheet is reversed, the second FRP sheet will have the greatest effect on the load, but in the second FRP sheet, the fiber direction extends in the direction orthogonal to the beam axis. Since the fibers are arranged as described above, there is no continuity of the fibers in the axial direction of the beam, and the shear load cannot be received by the entire second FRP sheet.

Since it is a reinforced structure using an FRP sheet, it is excellent in workability, workability, economy, and workability.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the reinforcing structure according to the present invention, the first
And a second FRP sheet. These FRP sheets include what is called a fiber reinforced plastic plate or prepreg, and include carbon fiber, aramid fiber,
The reinforcing fiber such as glass fiber or vinylon fiber is arranged in one direction and embedded in a thermosetting matrix resin known per se such as epoxy resin, unsaturated polyester resin or polyurethane resin to be formed thinly.

At the site, the lower surface of the beam to be reinforced and the two side surfaces are ground and cleaned. If the beam is cracked or missing, repair it before applying groundwork. After the base treatment, a primer of, for example, an epoxy resin is applied to the lower side surface and the two side surfaces of the beam to penetrate concrete. After that, an epoxy adhesive, which is the same type as the primer, is applied to the two sides, and the first FRP sheet is arranged so that the fibers extend in the axial direction of the beam.
Glue to each of the two sides. After the bonding is completed, a curing agent is applied to the first FRP sheet to cure the first FRP sheet. After the curing of the first FRP sheet is completed or before the curing is completed, the same kind of adhesive as described above is applied to the lower surface of the beam and the first FRP sheet, and the second FRP sheet is The fibers are arranged so as to extend in a direction orthogonal to the axis of the beam, and are bonded to the lower surface of the beam and the already-bonded first FRP sheet. After the bonding is completed,
A curing agent is applied to the second FRP sheet to cure the second FRP sheet.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A reinforcing structure, as shown in FIGS. 1 and 2, has a first FRP sheet 26 on two side faces 22, 23 of a building beam 20 having a lower side face 21 and two side faces 22, 23.
And then the lower surface 21 and the first FRP sheet 2
A second FRP sheet is bonded to 6 to reinforce the beam 20 by shearing.

The first FRP sheet 26 and the second FRP sheet 28 are made by arranging carbon fibers in one direction and embedding them in an epoxy-based matrix resin. First, the beam 20
An epoxy-based primer is applied to the two side surfaces 22 and 23 of the above, and an epoxy-based adhesive is further applied. First FR
The P sheet 26 has its fibers extending in the axial direction of the beam 20, and the first FRP sheet 26 has the columns 30, 30.
It is arranged so as to cover the entire surface up to the floor 32 and is bonded to the two side surfaces 22 and 23 ((b) of FIG. 1).

After adhering the first FRP sheet 26, an epoxy-based primer is applied to the lower side surface 21 of the beam 20, and an epoxy-based adhesive is applied to the lower side surface 21 and the first FRP sheet 26. The second FRP sheet 28 is so arranged that its fibers extend in a direction orthogonal to the axis of the beam 20, and
The second FRP sheet 28 is arranged so as to cover the entire surface between the columns 30 and 30 up to the floor 32, and is adhered to the lower side surface 21 and the already adhered first FRP sheet 26 ((c) of FIG. 1). After adhering the first FRP sheet 26, it is cured, and after adhering the second FRP sheet 28, it is cured to complete the reinforcing structure 34 ((a) of FIG. 1).

The reason why the first FRP sheet 26 is not adhered to the lower side surface 21 of the beam 20 is that the first FRP sheet 26 functions for shear reinforcement of the beam 20, but as described above, Shear reinforcement is based on being achieved by reinforcing the sides 22, 23 of the beam 20. When the FRP sheet is bonded to the lower side surface 21 of the beam 20, the effect of reinforcing the bending of the beam 20 is obtained. Therefore, when shear reinforcement and bending reinforcement are intended, instead of the above embodiment,
The first FRP sheet 26 is attached to the lower side surface 21 and the two side surfaces 2.
It may be adhered to 2, 23. In this case, the second FRP sheet 28 is the first FRP sheet 26.
It will be adhered to the lower surface 21 of the beam 20 via.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of a building beam shear reinforcement structure according to the present invention, in which (a) is a completed state, (b) is a state in which a first FRP sheet is bonded, and ( c) shows a state in which the second FRP sheet is adhered.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a cross-sectional view showing shear reinforcement of a beam of a reinforced concrete building.

[Explanation of symbols]

 20 Beam 21 Lower Side 22, 23 Side 26 First FRP Sheet 28 Second FRP Sheet

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location // B29K 105: 08 (72) Inventor Norimitsu Hayashida 1043 No. 1 Shimoyama, Onigakubo, Tsukuba, Ibaraki Company Kumagai Gumi Technical Research Institute (72) Inventor Tomoaki Tsujimura 1043-1, Shimoyama, Onigakushi, Tsukuba-shi, Ibaraki Kumagai Gumi Technical Research Institute Ltd. (72) Inventor Takeshi Naito 234 Takaseki, Kamichikari, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture Address Toho Rayon Co., Ltd. Research Institute (72) Inventor Masato Ando 234 Takaishi, Uechikari, Nagaizumi-cho, Sunto-gun, Shizuoka Prefecture Toho Rayon Co., Ltd. Research Institute (72) Inventor Yukio Asano No. 1 Nakatawara, Joetsu City, Niigata Prefecture Arisawa Co., Ltd. Inside Nakatahara Factory

Claims (1)

[Claims] 1. A shear reinforcement structure for a beam of a building having a lower side surface and two side surfaces, wherein the first fiber reinforced plastic sheet is adhered to each of the two side surfaces and the direction of the fibers is a beam. A first fiber-reinforced plastic sheet extending in the axial direction of the first fiber-reinforced plastic sheet, and a second fiber-reinforced plastic sheet bonded to the lower side surface and the first fiber-reinforced plastic sheet so as to extend over the lower side surface and the two side surfaces of the beam. A shear reinforcing structure for a beam of a building, comprising a plastic sheet and a second fiber-reinforced plastic sheet in which the direction of the fibers extends in a direction orthogonal to the axis of the beam.