JPH09217501A - Method for adhering fiber sheet to concrete member - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To transmit shear force and bending stress applied to a member reinforced by a fiber sheet to a wide range of the fiber sheet,
Further, to provide a method for adhering a fiber sheet to a concrete member, which improves the toughness of the member and prevents brittle fracture. When a fiber sheet (4) is bonded to the lower surface of a beam member (3), a solvent-type adhesive agent (5) such as an epoxy resin having a strong adhesive strength, which is usually used in a predetermined range at both ends of the lower surface of the beam member (3). The adhesive 6 having a weak adhesive force is applied to the central portion between the both ends, and the longitudinal direction of the beam member 3 and the fibers of the fiber sheet 4 are arranged in parallel. Bond the first layer. Further, after the adhesive 7 is applied to the lower surface of the bonded fiber sheet 4 as described above, the second-layer fiber sheet 4 is bonded, and the third-layer fiber sheet 4 is bonded in the same manner as above. To do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adhering a concrete member to a concrete member such as a pillar or a beam in an existing reinforced concrete (RC) structure by using a fiber sheet.

[0002]

2. Description of the Related Art A conventional method for adhering a fiber sheet to a concrete member is such that carbon fiber is applied to the entire outer peripheral surface of a pillar member, the lower surface of a beam member or the like which requires reinforcement of a reinforced concrete structure.
A fiber sheet in which a fiber material such as aramid fiber is arranged in one direction is attached using an adhesive or the like so that the direction of tension acting on the concrete member is parallel to the fiber material. As a result, the concrete member is reinforced against deformation, thereby preventing the concrete member from cracking and improving the seismic performance of the structure.

[0003]

SUMMARY OF THE INVENTION However,
In the conventional method for adhering a fiber sheet to a concrete member, since the entire bonding surface between the concrete member and the fiber sheet is firmly adhered with an adhesive, the member proof strength against shearing and bending at the time of earthquake etc. is improved. However, on the other hand, when a crack or the like occurs in a part of the member, the fibrous sheet easily breaks at an early stage, resulting in brittle fracture of the member.

This is because, as shown in FIG. 7, the strain of the reinforcing bars embedded in the concrete member has a gradual slope over a wide range of the concrete member, whereas the fiber sheet has only a cracking position in the concrete. This is clear from the fact that the tensile force is concentrated and the strain locally increases. Therefore, the present invention has been made by paying attention to the above-mentioned conventional unsolved problems, and can transmit the shearing force and the bending stress applied to the member reinforced by the fiber sheet to a wide range of the fiber sheet, and the member It is an object of the present invention to provide a method for adhering a fiber sheet to a concrete member, which is capable of improving the toughness and preventing brittle fracture.

[0005]

In order to solve the above problems, a method for adhering a fiber sheet to a concrete member according to the present invention is to reinforce the concrete member by attaching a fiber sheet to the surface of the concrete member to which a tensile force is applied. In the method for adhering a fiber sheet of a concrete member, a portion capable of relative displacement between the fiber sheet and the concrete member is provided by partially changing an adhesive force between the concrete member and the fiber sheet. I am trying.

[0006] Thus, at places where the fiber sheet has a large adhesive force, the surface of the concrete member is firmly restrained and supported to bear the tensile force, thereby preventing shearing, bending deformation, etc. of the concrete. Further, in a place where the adhesive force of the fiber sheet is small, the fiber sheet and the concrete member are relatively displaced to allow a certain amount of deformation, so that the strength of the member is not unnecessarily lowered and the bending applied to the member is reduced. Makes the behavior to shear tough.

The above method is embodied by bonding the concrete member and the fiber sheet with a plurality of adhesives having different adhesive strengths. For example, the adhesive force is applied to the central portion where the deformation amount of the reinforcing member is large. In some cases, an adhesive having a weak adhesive strength is used and an adhesive having a strong adhesive force is used at the end portion.
On the other hand, by alternately providing an adhesive portion and a non-adhesive portion on the bonding surface between the concrete member and the fiber sheet, the adhesive portion bears the tensile force applied to the member and the non-adhesive portion allows the elongation of the fiber sheet. However, the member can be toughened by dispersing the stress when the member is cracked.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the method for adhering a fiber sheet to a concrete member according to the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a structure, which is made of reinforced concrete. In order to improve the seismic performance of the structure 1, the fiber sheet 4 is adhered to the lower surface of the beam member 3 here.

The fiber sheet 4 is formed by arranging lightweight carbon fibers having a high elastic modulus and strength in the same direction and solidifying and integrating them with an adhesive. Further, this carbon fiber is specifically a high strength carbon fiber (HS
CF), high elastic carbon fiber (HMCF), etc. can be applied. In addition to the above, the material of the fiber sheet 4 is high-strength glass fiber (GF), aramid fiber (AF), glass fiber (GF), steel fiber (SF), synthetic fiber (PF), or a combination thereof. Etc.

A specific method of adhering the fiber sheet 4 will be described. When adhering the fiber sheet 4 to the lower surface of the beam member 3, as shown in FIG. A solvent-type adhesive 5 such as an epoxy resin having a strong adhesive strength, which is usually used in the range, is applied, and an adhesive 6 having a weak adhesive strength is applied to the central portion between the both ends. After arranging the fibers of the fiber member 4 in parallel with the longitudinal direction of the beam member 3, the first layer is bonded.

The adhesive 6 may be an inorganic water-based adhesive such as mortar. Further, adhesive 5, 6 is applied to the lower surface of the bonded fiber sheet 4 in the same manner as described above.
After applying, the second-layer fiber sheet 4 is adhered, and the third-layer fiber sheet 4 is adhered in the same manner as above.

Here, the second and third fibrous sheets 4 have the same adhesive strength at both ends as the first layer,
Although the adhesive strength is weakened in the central portion, the normal adhesion may be applied to the second and third layers. Further, although the case where the third-layer fiber sheet 4 is laminated has been described in this embodiment, the fiber sheet 4 is not necessarily composed of three layers, and may be composed of one layer or a plurality of other layers.

Further, in the above embodiment, the case where the adhesive is applied to the lower surface of the beam member 3 has been described, but the fiber sheet 4 to be applied may be applied after applying the adhesive. . As a result, when the bending stress applied to the beam member 3 becomes excessive due to the occurrence of an earthquake or the like, and the strain in the central portion becomes large and cracks occur or are likely to occur, the beam in the central portion with a large strain amount is generated. Since the adhesive force between the member 3 and the fiber sheet 4 is weakened, the adhesive surface between the fiber sheet 4 and the beam member 3 is displaced at the portion where the adhesive force is weakened, and the crack occurrence point C is centered. Since a relative displacement is generated over a wide range, it is possible to allow the beam member 3 to deform to some extent.

Further, since the limit elongation amount of the fiber sheet 4 becomes large, the beam member 3 can be made to have a tough behavior without the fiber sheet 4 being easily broken. Next, another embodiment of the present invention will be described. The present invention
A modified example of the method for adhering the fiber sheet 4 in the above-described embodiment is shown, and the description other than this is the same and therefore omitted.

First, as shown in FIG. 3, the lower surface of the beam member 3 which needs to be reinforced is coated with an adhesive agent such as an ordinary epoxy resin at intervals of about 30 cm in this case to form an adhesive portion 9. After alternately providing the non-adhesive portions 10, the first-layer fiber sheet 4 is attached to the lower surface of the beam member 3. Of course, this interval can be appropriately changed in consideration of the span of the beam member 3, the type of adhesive, and the like.

Next, the non-bonded portion 1 in the above-mentioned first layer
The adhesive layer 9 is provided on the lower side of 0 and the non-adhesive section 10 is provided on the lower side of the adhesive section 9 of the first-layer fiber sheet 4, and then the second-layer fiber sheet 4 is attached. . In addition, 1
The adhesive portion 9 and the non-adhesive portion 10 are provided at the same positions as the adhesive agent of the layer, and the fiber sheet 4 of the third layer is attached.

As described above, the adhesive portions 9 and the non-adhesive portions 10 are alternately provided on the lower surface of the beam member 3 at predetermined intervals, whereby the adhesive member 9 is subjected to shearing and bending applied to the beam member 3 of the fiber sheet 4. Pay directly in the pulling direction. Further, when the shearing and bending stress applied to the beam member 3 becomes excessive and the strain at the central portion of the beam member 3 becomes large, and cracks occur or are likely to occur, the non-bonded portion 1
0 causes relative displacement with the beam member 3 over a wide range around the crack occurrence point C, and the beam member 3 can be deformed to some extent.

Therefore, the critical elongation of the fiber sheet 4 as a whole can be increased so that the stress locally applied to the fiber sheet 4 can be dispersed in a wide range, whereby the fiber sheet 4 is prevented from prematurely breaking and the beam member 3 is toughened. Behavior can be achieved. In this embodiment, the case where the fiber sheet 4 is made into three layers to reinforce the beam member 3 has been described, but the present invention is not limited to this, and the fiber sheet 4 is made of one layer or a plurality of layers other than three layers. You can also

The method for adhering the fiber sheet 4 of each layer is not limited to this, and for example, as shown in FIG.
By providing the adhesive portion 9 and the non-adhesive portion 10 at the same position on the third layer and the third layer and completely adhering the entire second layer, the layer on which the non-adhesive portion 10 is provided and the layer that is completely adhered are alternately formed. It can also be laminated. Further, as shown in FIG. 5, the adhesive portions 9 and the non-adhesive portions 10 may be alternately provided only in the first layer, and the other layers may be completely adhered as usual.

Further, in this embodiment, the case where the adhesive portion 9 and the non-adhesive portion 10 have the same phase in the width direction of the fiber sheet has been described, but as shown in FIG. By alternately providing the portions 9 and the non-adhesive portions 10 and arranging them in a lattice shape as a whole, the beam member 3 can be made to be more tough. In addition, as the adhesive used in the above-described embodiment, polymer cement mortar, polymer mortar, or the like can be used.

Further, in the above-mentioned embodiment, the case where the beam member 3 is reinforced has been described, but it can be applied to the column member 2. Further, in the above-described embodiment, the case where the structure 1 made of reinforced concrete is reinforced has been described, but the present invention is not necessarily limited to this, and is applied to all concrete members such as steel-framed reinforced concrete (SRC) structures. Of course you can.

[0022]

As described above, according to the method for adhering a fiber sheet of a concrete member of the present invention, the adhesive force between the concrete member and the fiber sheet is partially changed, or the adhering portion and the non-adhering portion are alternated. In addition, the bending and shearing force applied to the concrete member can be directly transmitted to the fiber sheet, and the strain applied to the fiber sheet is dispersed over a wide range to make the behavior of the reinforcing member tough and to make it brittle due to stress concentration. It is possible to prevent destruction.

As a result, it is possible to greatly improve the seismic performance without carrying out a large-scale repair work on the existing concrete structure.

[Brief description of drawings]

FIG. 1 is a side view showing a structure applied to a method for adhering a fiber sheet of a concrete member according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a method for adhering a fiber sheet to a concrete member and a structure thereof according to an embodiment of the present invention.

FIG. 3 is a side sectional view showing a method for adhering a fiber sheet to a concrete member and a structure thereof according to another embodiment of the present invention.

FIG. 4 is a side sectional view showing a method for adhering a fiber sheet to a concrete member and a modification of the structure according to another embodiment of the present invention.

FIG. 5 is a side sectional view showing a method for adhering a fiber sheet to a concrete member and a modification of the structure according to another embodiment of the present invention.

FIG. 6 is a plan cross-sectional view showing a modified example of a method for adhering a fiber sheet to a concrete member and a structure thereof according to another embodiment of the present invention.

FIG. 7 is a strain curve of a reinforcing bar and a fiber sheet when a crack occurs in the conventional method for adhering a fiber sheet to a concrete member.

[Explanation of symbols]

 1 ... Structure 2 ... Pillar member 3 ... Beam member 4 ... Fiber sheet 5-8 ... Adhesive 9 ... Adhesive part 10 ... Non-adhesive part

Claims (3)

[Claims] 1. A method of adhering a fiber sheet to a surface of a concrete member to which a tensile force is applied to reinforce the concrete member, the adhesive force between the concrete member and the fiber sheet being partially changed. A method for adhering a fiber sheet to a concrete member, characterized in that a portion capable of relative displacement between the fiber sheet and the concrete member is provided by the above. 2. The fiber sheet for a concrete member according to claim 1, wherein the concrete member and the fiber sheet are bonded by a plurality of adhesives having different adhesive strengths. Bonding method. 3. A method of adhering a fiber sheet to a surface of a concrete member to which a tensile force is applied to reinforce the concrete member, comprising: A method for adhering a fiber sheet to a concrete member, characterized in that a portion capable of relative displacement between the fiber sheet and the concrete member is provided by alternately providing adhering portions.