JP2004316320A - Method of reinforcing borehole peripheral part for existing concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of reinforcing a borehole peripheral part for an existing concrete structure having excellent workability, obtaining a reinforcing effect of high quality regardless of the construction skill of a constructor and securing a sufficient reinforcing effect even with a change in surrounding environment. <P>SOLUTION: In the method of reinforcing a peripheral part 1b of a borehole 1a formed after laying for a skeleton 1 of the existing concrete structure, a fiber reinforced plastic molded plate 10 having an opening 10a including at least the borehole 1a and having a fiber layer laminated so that at least the intersecting directions of fiber are symmetric with respect to the center cross section in a plate thickness direction, is used, and the opening 10a is adjusted to the borehole 1a to stick the fiber reinforced plastic molded plate 10 to the peripheral part 1b through an adhesive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３８】
【表２】

【００３９】
図４は、同図（ａ）に試験体Ａ，試験体Ｂ，試験体Ｃの測定結果を示しており、同図（ｂ）に試験体Ｄの試験結果を示している。これらの結果から明らかなように、試験体Ａと試験体Ｃとの比較では、穿孔と合致した開口を有する炭素繊維強化プラスチック成形板を貼ることによって、初期ひび割れ発生荷重が４５％向上し、また、補強を施さない試験体Ｃでは、初期ひび割れ発生後９５ｋＮ付近で鉄筋の降伏点に達した（Ｃ２）のに対して、補強を施した試験体Ａでは、１３９ｋＮまで耐力を保持することができる（Ａ２）。また、試験体Ｂと試験体Ｃとの比較では、穿孔に対してこれを内包するような若干大きい開口を有する繊維強化プラスチック成形板を貼ることによっても同様の補強効果が得られることがわかる。
【００４０】
そして、穿孔に対して補強を施した場合（試験体Ａ，試験体Ｂ）には、穿孔を形成しなかった場合（試験体Ｄ）と比較しても、初期ひび割れ発生荷重が８５〜９０％くらいまで回復していることが分かる。この際比較対象の試験体Ｄでは、鉄筋の切断が為されていないので、両者に差が生じるのは当然であるが、初期ひび割れ発生の防止という観点では充分な補強効果が得られていることが確認できる。
【００４１】
【発明の効果】
本発明はこのように構成されるので、施工性が良好で、施工者の施工熟練度に拘わらず高品質の補強効果が得られ、しかも、周辺環境の変化に対しても充分な補強効果を確保することが可能な既設コンクリート構造物に対する穿孔周辺部補強工法を提供することができる。
【図面の簡単な説明】
【図１】本発明の実施形態に係る補強工法の概要を示す説明図である。
【図２】本発明の実施形態に係る繊維強化プラスチック成形板を示す説明図である。
【図３】本発明の実施形態に係る補強工法の作業手順を示すフローである。
【図４】実施例の試験結果を示すグラフである。
【符号の説明】
１ 躯体
１ａ 孔
１ｂ 穿孔周辺部
１０ 繊維強化プラスチック成形板
１０ａ 開口[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reinforcing method for reinforcing an existing concrete structure around a perforation formed after laying.
[0002]
[Prior art]
For existing concrete structures, through-holes may be formed in the skeleton (walls, etc.) of the structure for reasons such as a change in use conditions or an increase in attached facilities. If a hole such as a wall is pierced after being laid, local stress concentration due to shearing force or the like occurs at the periphery of the hole, or a decrease in the proof strength of the frame due to a cross-sectional defect occurs, which causes cracking. If a crack occurs in the frame, even if it is a non-structural wall, the fire protection, waterproofing, and soundproofing functions provided by the frame will be impaired. Needs to be reinforced.
[0003]
Conventionally, as a method for reinforcing the periphery of the perforation, a method of bonding steel plates to both sides of the surface of the skeleton at the periphery of the perforation has been performed. However, according to such a construction method, a heavy steel plate is bonded to the surface of the skeleton, so when vertical walls or the like are to be used as the target skeleton, erection with an anchor or the like is required until the adhesive is cured, which requires a large amount of work. At the same time, during the curing period until the adhesive is cured, there is a problem that the erection is in the way and hinders the operation of the peripheral part. In addition, in the case of reinforcing with a steel plate, the projections become large due to the thickness of the steel plate and anchor bolts, and the situation around the target skeleton is extremely changed, which causes a problem in securing the appearance and surrounding space.
[0004]
Therefore, a construction method using a fiber reinforced plastic lighter than a steel plate has been proposed (see Patent Document 1 below). This method involves applying an epoxy-based adhesive to the surface of a concrete structure, for example, around a through hole for equipment piping, after applying a surface treatment to the surface of the hole, and opening the hole in the concrete structure. A plastic sheet having an opening matched to the above is attached. In this method, a fiber-reinforced plastic sheet in which fibers are arranged in one direction is attached to the periphery of the perforation at the construction site so that the fiber directions intersect, and after the attachment of the plastic sheet is completed, a curing agent is applied to the surface. It is applied to cure the fiber reinforced plastic sheet.
[0005]
[Patent Document 1]
JP-A-9-125601
[Problems to be solved by the invention]
In the above-mentioned method using a fiber reinforced plastic sheet, since the sticking work is performed while adjusting the crossing angle of the fiber at the construction site, the work on the site becomes complicated, the workability is poor, and depending on the constructor, There is a problem that quality tends to vary.
[0007]
In order to cope with this problem, it is conceivable to use a fiber-reinforced plastic plate formed in advance. Generally, a fiber-reinforced plastic plate has different mechanical properties depending on the direction of the fiber. Therefore, in order to make the bending characteristics in the out-of-plane direction of the plate equal to two orthogonal bending directions, for example, the fiber direction is set to 0. The outermost layers are arranged so that the fiber directions are orthogonal to each other by, for example, a two-layer structure of ° / 90 °. However, in the case where a fiber reinforced plastic plate having an arrangement in which the fiber directions of the outermost layer are orthogonal to each other is used in view of such bending characteristics, the thermal expansion coefficient of the fibers is generally different between the axial direction and the orthogonal direction. The change tends to warp the plate.
[0008]
In the method of reinforcing the perimeter of the perforation, if a material that is susceptible to thermal deformation (warpage) is used, the plate is warped in response to a change in ambient temperature, causing deterioration of the bonding state, and There is a problem that the reinforcing effect cannot be obtained. In particular, when holes for laying air intake and exhaust ducts for air conditioning facilities are formed in the concrete structure body, it is necessary to be aware that a certain degree of temperature change will occur around it, so the heat Without consideration of the mechanical properties, a sufficient reinforcing effect cannot be obtained. In addition, when the above-mentioned reinforcement is applied to the outer wall surface in a region where the temperature difference between daytime and nighttime is large or a region where the seasonal temperature difference is large, a sufficient reinforcing effect cannot be obtained due to the deformation of the plate over time. .
[0009]
The present invention has been proposed in order to address such a problem, and has good workability, a high-quality reinforcing effect can be obtained irrespective of the construction skill of the installer, and moreover, the surrounding environment can be improved. An object of the present invention is to provide a method of reinforcing a perimeter of an existing concrete structure capable of securing a sufficient reinforcing effect against changes.
[0010]
[Means for Solving the Problems]
In order to achieve such an object, a method for reinforcing a perimeter of an existing concrete structure according to the present invention has the features according to the following claims.
[0011]
The invention according to claim 1 is a construction method for reinforcing a peripheral portion of a perforation formed after laying, for an existing concrete structure, the method including an opening including at least the perforation, and preventing a change in the surrounding environment. A fiber-reinforced plastic molded plate which maintains flatness by adjusting the openings to the perforations, and affixes the fiber-reinforced plastic molded plate to the peripheral portion via an adhesive.
[0012]
The invention according to claim 2 is a method for reinforcing a peripheral portion of a perforation formed after the existing concrete structure is laid, the method including an opening including at least the perforation, and at least a crossing direction of fibers. Using a fiber reinforced plastic molded plate having a fiber layer laminated so as to be symmetrical with respect to the plate thickness direction center cross section, aligning the opening with the perforation, the fiber reinforced plastic molded plate via an adhesive It is characterized in that it is attached to the peripheral part.
[0013]
According to a third aspect of the present invention, in the method of reinforcing a perforated portion of an existing concrete structure according to the first or second aspect, the fiber-reinforced plastic molded plate comprises an even number of fiber layers.
[0014]
According to a fourth aspect of the present invention, in the method for reinforcing a perimeter of an existing concrete structure according to the first or second aspect, the fiber-reinforced plastic molded plate comprises three fiber layers, and an outermost layer is formed in the same direction. It is a fiber layer in which the central layer is arranged in a different direction from the central layer and the fiber amount is twice that of the outermost layer.
[0015]
According to a fifth aspect of the present invention, in the method for reinforcing a peripheral portion of an existing concrete structure according to any one of the first to fourth aspects, the fiber-reinforced plastic molded plate is attached to only one surface of the peripheral portion. Features.
[0016]
According to the invention having the above features, the following effects can be obtained.
[0017]
In existing concrete structures, if holes are formed in the skeleton by drilling after laying, local stress concentration due to shearing force etc. at the periphery of the drilling and reduction in proof stress due to cross-sectional defects occur, which causes cracks. As a cause of the occurrence, by attaching a fiber-reinforced plastic molded plate with openings around the perforation via an adhesive, a reinforcing effect to maintain the proof stress close to the proof stress of the target frame before perforation is obtained. Can be
[0018]
According to the present invention, firstly, since a fiber-reinforced plastic molded plate that maintains flatness against changes in the surrounding environment is used, the work at the construction site can be simplified, and the skill of the installer can be reduced. Regardless, a high-quality reinforcing effect can be obtained, and a stable reinforcing effect can be maintained over time. And, since a lightweight fiber-reinforced plastic molded plate is attached to the periphery of the perforation, there is no need to provide a bridge such as an anchor, and the periphery of the reinforcement is open even during the curing period when the adhesive cures. Other tasks can be performed in parallel.
[0019]
Secondly, since a fiber-reinforced plastic molded plate having a fiber layer laminated so that at least the crossing direction of the fibers is symmetrical with respect to the central cross section in the thickness direction is used, the molded plate is flat against thermal expansion. Sex can be maintained. Thereby, the above-described operation can be obtained.
[0020]
Third, by forming the fiber-reinforced plastic molded plate from an even number of fiber layers, a symmetric fiber layer laminated structure can be easily obtained with the lamination surface being a center cross section in the plate thickness direction. Thereby, the above-described operation can be obtained.
[0021]
Fourth, the fiber-reinforced plastic molded plate is composed of three fiber layers, the outermost layer being a fiber layer arranged in the same direction, the center layer being arranged in a different direction from the outermost layer, and doubling the fiber amount. Since the fiber layer is formed as described above, a symmetric fiber layer laminated structure can be obtained by setting the middle section of the center layer to the center section in the plate thickness direction. Thereby, the above-described operation can be obtained.
[0022]
Fifth, since the fiber-reinforced plastic molding plate is stuck on only one surface of the periphery of the perforation, work can be performed easily, and construction is possible even in a situation where work can be performed only on one surface. The scope of application is less limited. In particular, when the outer wall of the building is to be used as the target skeleton, it is sufficient to attach a fiber-reinforced plastic molded plate only to the outside of the building, so that the construction can be completed without affecting the room, and In the case where work cannot be performed, a sufficient measure can be taken by attaching a fiber-reinforced plastic molded plate only to the indoor side. In the case where the purpose is to reinforce the target skeleton to recover to the same strength as before the drilling, it can be sufficiently achieved by attaching a fiber-reinforced plastic molded plate only to one surface of the peripheral portion of the drilling. In combination with the first to third features, highly effective reinforcement can be performed.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of a reinforcing method according to an embodiment of the present invention. In the reinforcing method according to this embodiment, a hole 1a is formed in a skeleton 1 such as a wall of a concrete structure using a diamond core drill or the like, and after the hole 1a is formed, cracks in a peripheral portion 1b of the hole are prevented. Then, a fiber-reinforced plastic molded plate 10 having an opening 10a corresponding to the hole 1b is attached to a perforated peripheral portion 1b on one side of the body 1 surface. The size of the opening 10a may be the same as the size of the hole 1b, or may be larger than that and at least include the hole 1b.
[0024]
The fiber-reinforced plastic molded plate 10 is a molded plate obtained by impregnating a reinforcing fiber (for example, carbon fiber) with a resin in advance and curing the resin, and has an opening 10a formed by machining according to a hole 1a to be drilled after molding. It is. By using such a molded plate, there is an advantage that, in comparison with a case where a conventional fiber-reinforced plastic sheet is used, the attaching work at the construction site is facilitated, and the variation in quality by the constructor is reduced. . Furthermore, since the amount of resin impregnated into the fiber is controlled to be constant, the thickness of the sheet after molding is constant, and since the opening is formed in advance by machining after molding, the dimensions are set at the construction site. No need. Therefore, there is an advantage that the aesthetic appearance of the finish is good and the workability is good.
[0025]
The fiber-reinforced plastic molded plate 10 according to the embodiment of the present invention employs a structure that maintains flatness against changes in the surrounding environment. For example, it has a plurality of laminated fiber layers, and the fiber direction of each fiber layer is arranged in a cross direction as shown in FIG.
[0026]
In the embodiment shown in FIG. 3A, a four-layer (even number layer) structure of fiber layers S ₀₁ , S ₀₂ , S ₀₃ , and S ₀₄ is adopted, and the fiber arrangement direction of each fiber layer is set to 0 °. / 90 ° / 90 ° / 0 °. As a result, the outermost layers S ₀₁ and S ₀₄ are fiber layers arranged in the same direction, and the crossing direction of the fiber arrangement is symmetric with respect to the center lamination boundary surface O ₀ as the central section in the plate thickness direction. It has a structure.
[0027]
When the fiber-reinforced plastic molded plate 10 having such a structure is used, the front and back surfaces exhibit the same thermal expansion characteristics, so that warpage does not occur even when the temperature changes. Therefore, it is possible to obtain a fiber-reinforced plastic molded plate that maintains flatness against changes in the surrounding environment.
[0028]
Further, in the fiber-reinforced plastic molded plate 10 having such a structure, the bending rigidity in the bending around the axis perpendicular to the paper surface (bending in the direction of the arrow in the drawing) is smaller than the bending rigidity in the direction perpendicular thereto (１ ／ to 1/1). 7 times). According to this, by bending the fiber reinforced plastic molded plate 10 in the direction of the arrow shown in the figure, the plate can be easily curved. By utilizing this, a part of the fiber-reinforced plastic molded plate 10 is pasted in a curved state, and the whole is pasted while gradually flattening the plate. Can be attached.
[0029]
In the embodiment shown in FIG. 2B, a three-layer structure of fiber layers S ₁₁ , S ₁₂ , and S ₁₃ is employed, and the fiber arrangement direction of each fiber layer is set to 0 ° / 90 ° / 0 °. and has set fiber amount α of the center of the fiber layer _{S 12} to 2 times the outermost _{S 11, S 13 (2α)} with which. As a result, the outermost layers S ₁₁ and S ₁₃ are fiber layers arranged in the same direction, and the center cross section O ₁ of the center fiber layer S _{12 is taken as} the center cross section in the thickness direction, and the fiber arrangement intersects with this surface. The structure is symmetrical in direction and fiber amount.
[0030]
In the embodiment shown in FIG. 3C, an eight-layer (even layer) structure of the fiber layers S ₂₁ , S ₂₂ , S ₂₃ , S ₂₄ , S ₂₅ , S ₂₆ , S ₂₇ , and S ₂₈ is employed. The fiber arrangement direction of each fiber layer is set to 0 ° / 0 ° / 90 ° / 90 ° / 90 ° / 90 ° / 0 ° / 0 °. Thus, the outermost layer S _21, S ₂₈ is a fibrous layer which is arranged in the same direction, the center of the laminated boundary surface O ₂ as the thickness direction center section, is symmetrical cross direction of the fiber array with respect to this plane It has a structure.
[0031]
Also in these embodiments, as in the above-described embodiment, the front and back surfaces exhibit the same thermal expansion characteristics, so that there is no warping against a temperature change, and the fiber reinforced plastic molding is performed in the direction of the arrow shown in the figure. Since the plate can be easily curved by bending the plate, it is possible to perform high-quality bonding while expelling bubbles in the adhesive.
[0032]
FIG. 3 is a flowchart showing a work procedure of the reinforcing method according to the embodiment of the present invention. The work procedure will be described in conjunction with the description of FIG. In the drilling (core removal) work, after a reinforcing bar in a concrete structure is detected, a portion without a reinforcing bar is selected, and a through hole is formed in the target frame using a diamond core drill or the like (P ₀ ). Then, the state where there is no smooth fragile portion and dirt by the concrete surface of the perforated peripheral portion 1b (base) Thunder Keren like to surface treatment (P _1). Thereafter, the sticking position of the fiber reinforced plastic molded plate 10 is blacked out, an adhesive (epoxy resin adhesive or the like) is applied to the bonding surface of the fiber reinforced plastic molded plate 10 with a uniform thickness, and further, the blacking position of the base is obtained. Then, an adhesive (epoxy resin adhesive or the like) is applied to a uniform thickness (P ₂ ). Next, in a state where the fiber-reinforced plastic molded plate 10 is curved, a part of the end is adhered to the base, and the whole is pasted on the base while returning flat for removal (P ₃ ). At this time, by sticking the air bubbles out of the adhesive, it is possible to prevent a space from being formed in the adhesive layer. Thereafter, curing is performed until the adhesive is hardened (P ₄ ), and the work is completed by cleaning the periphery of the construction (P ₅ ).
[0033]
【Example】
Hereinafter, more specific examples of the present invention will be described.
[0034]
[Fiber-reinforced plastic molded plate] A carbon fiber-reinforced plastic plate (CFRP plate) was molded by an autoclave molding method, and the arrangement of the fiber layers was set to 0 ° / 90 ° / 90 ° / 0 ° (see FIG. 2A). . The specifications of the formed plate were a fiber weight of 150 g / m ² , a resin content of 35 wt%, and a plate thickness of 0.6 mm. The outer diameter is 400 mm × 400 mm, and the opening diameter is set to 125φ in the first example so as to match the perforation diameter of 125φ, and in the second example, it is set to 200φ including the perforation diameter of 125φ.
[0035]
[Adhesive] As the adhesive, one that does not matter odor, has little resin dripping (grease-like), and has a short curing time is suitable. As an adhesive satisfying these, an epoxy resin adhesive (product name: Tohodite CP471) composed of a base material: a bisphenol A type epoxy resin and a curing agent: a modified alicyclic polyamine can be employed.
[0036]
[Performance test] Using a test piece of a concrete structure (concrete mixing strength 18 N / mm ² , length: 600 mm × width: 600 mm × thickness: 150 mm, three single bar arrangements) A hole of 125φ was formed in a state where the rebar was cut, and a tensile load test using a load cell was performed on each of the test pieces in Table 1 while supporting three rebars. The test results are shown in Table 2 and FIG.
[0037]
[Table 1]

[0038]
[Table 2]

[0039]
FIG. 4A shows the measurement results of the test pieces A, B and C, and FIG. 4B shows the test results of the test piece D. As is clear from these results, in the comparison between the specimen A and the specimen C, the initial crack initiation load was improved by 45% by attaching the carbon fiber reinforced plastic molded plate having the opening corresponding to the perforation. On the other hand, in the specimen C without reinforcement, the yield point of the reinforcing steel reached around 95 kN after the initial crack generation (C2), whereas in the specimen A with reinforcement, the proof stress could be maintained up to 139 kN. (A2). In addition, a comparison between the specimen B and the specimen C shows that the same reinforcing effect can be obtained by attaching a fiber-reinforced plastic molded plate having a slightly large opening to include the perforation.
[0040]
When the perforation is reinforced (specimen A, specimen B), the initial crack generation load is 85 to 90% even when compared with the case where no perforation is formed (specimen D). You can see that it has recovered to about. At this time, since the reinforcing bar was not cut in the test sample D to be compared, it is natural that there is a difference between the two, but a sufficient reinforcing effect is obtained from the viewpoint of preventing the occurrence of initial cracks. Can be confirmed.
[0041]
【The invention's effect】
Since the present invention is configured in this manner, the workability is good, a high-quality reinforcing effect can be obtained regardless of the construction skill of the constructor, and a sufficient reinforcing effect can be obtained with respect to changes in the surrounding environment. It is possible to provide a perforated peripheral part reinforcement method for an existing concrete structure that can be secured.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of a reinforcing method according to an embodiment of the present invention.
FIG. 2 is an explanatory view showing a fiber-reinforced plastic molded plate according to an embodiment of the present invention.
FIG. 3 is a flowchart showing a work procedure of a reinforcing method according to the embodiment of the present invention.
FIG. 4 is a graph showing test results of Examples.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Frame 1a Hole 1b Peripheral part 10 Fiber-reinforced plastic molded plate 10a Opening

Claims (5)

A method of reinforcing the periphery of a perforation formed after laying on an existing concrete structure,
Using a fiber-reinforced plastic molded plate having an opening at least including the perforation and maintaining flatness against changes in the surrounding environment, aligning the opening with the perforation, and bonding the fiber-reinforced plastic molded plate with an adhesive A perforated peripheral part reinforcement method for an existing concrete structure, wherein the peripheral part is attached to the peripheral part. A method of reinforcing the periphery of a perforation formed after laying on an existing concrete structure,
Using a fiber-reinforced plastic molded plate having a fiber layer laminated so that at least the cross direction of the fibers is symmetrical with respect to the central cross section in the plate thickness direction, having an opening that at least includes the perforation, A method of reinforcing a perimeter of an existing concrete structure, wherein the fiber-reinforced plastic molded plate is attached to the periphery through an adhesive. 3. The method according to claim 1, wherein the fiber-reinforced plastic molded plate comprises an even number of fiber layers. The fiber-reinforced plastic molded plate is composed of three fiber layers, the outermost layer being a fiber layer arranged in the same direction, the central layer being arranged in a different direction from the central layer, and the amount of fibers being twice that of the outermost layer. The method for reinforcing a perforated portion of an existing concrete structure according to claim 1 or 2, wherein the fiber layer is a reinforced fiber layer. The method for reinforcing a perimeter of an existing concrete structure according to any one of claims 1 to 4, wherein the fiber-reinforced plastic molded plate is attached to only one surface of the perimeter.

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