JP2004176361A - Repair method of damaged concrete construction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repair method of a damaged concrete construction capable of being implemented with the reduced number of processes and greatly shortening a construction period. <P>SOLUTION: By arranging shell members 2 to the damaged concrete construction 1 at a gap 6, and filling the gap 6 with a filler 3, the method simultaneously performs both the filling of the gap 6 and the filling of a crack in a damaged section. The quality of a material and dimensions of the shell member can be decided by designed shearing proof stress deducting a part of a loading burden in an unrepaired section of an existing concrete construction and a designed toughness factor calculated on the basis thereof. <P>COPYRIGHT: (C)2004,JPO

Description

【００１８】
終局状態の破壊形式は、改修前の供試体についてはいずれもせん断破壊であったのに対し、改修後はいずれも曲げ破壊になった。ここで、破壊形式の判定は、終局時におけるひび割れ状況及び外殻部材２ｄ，２ｅ内に配置した帯鉄筋のひずみにより判定した。
また、改修後の供試体の靭性率は、Ｒ１０供試体では大幅に設計靭性率を上回り、Ｒ２０供試体では正側の靭性率が設計靭性率をやや下回ったものの、負側の靭性率は設計靭性率を上回る結果が得られた。
【００１９】
本発明の損傷したコンクリート構造物の改修方法は、完全にひび割れを補修する方法ではないが、ひび割れ補修の不確実な部分をあらかじめ控除して設計することにより、目標とする性能を簡単な改修方法で確保することができる。すなわち、充填材３によって充分にひび割れが補修されない部分があると予想される場合は、その部分を控除した設計をおこない、性能が目標を下回る場合は、外殻部材２の材質や寸法、又は充填材３の材質や充填材３を充填する隙間６の寸法を変更することにより強度を上げて、改修後の構造物に要求される耐力を満たすような外殻部材２又は充填材３を選択して設計すればよい。
【００２０】
【発明の効果】
本発明の損傷したコンクリート構造物の改修方法は以上説明したようになるから次のような効果を得ることができる。
＜イ＞従来の補修工程を省略できるので、工期を大幅に短縮することができる。また、充填材の材料費が増加したとしても、工期の短縮による経済効果を得ることができる。
＜ロ＞補修が充分におこなわれない部分の耐力は計算に入れないで設計をおこなうため、簡単な方法で改修をおこなっても目標とする性能を確実に確保することができる。
【図面の簡単な説明】
【図１】本発明の損傷したコンクリート構造物の改修方法の実施例の説明図。
【図２】せん断損傷の状態を表した説明図。
【図３】外殻部材の実施例の平面図。
【図４】（ａ）実験に使用した供試体の平面図。（ｂ）実験に使用した供試体の側面図。
【図５】（ａ）Ｒ１０供試体の実験結果を表した水平変位と水平荷重の関係図。（ａ）Ｒ２０供試体の実験結果を表した水平変位と水平荷重の関係図。
【図６】従来の補修工事及び補強工事の手順を示した説明図。
【符号の説明】
１・・・コンクリート構造物
２・・・外殻部材
３・・・充填材
６・・・隙間[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for repairing a concrete structure damaged by an earthquake, a car collision, or the like.
[0002]
[Prior art]
As seen in the Hyogoken-Nanbu Earthquake, reinforced concrete columns and beams can be significantly damaged by seismic loads. In this case, severely damaged items are removed and rebuilt, but depending on the degree of damage, repair work such as repair work or reinforcement work is often performed, and restoration is often performed.
For example, in the renovation work targeting the concrete column a, as a repair work, a known method such as an injection method, a filling method, a replacement method, a spraying method, a patching method, a prepacked method, a concrete laying method, a mortar as a reinforcing work. Known methods such as a spraying method, a precast panel winding method, a steel sheet winding method, an FRP sheet winding method, and an FRP spraying method have been implemented.
All of the above repair work methods are a combination of repair work and reinforcement work. Here, in general, repair work refers to work aimed at restoring or improving functions other than strength (salt damage, neutralization, frost damage, etc.), and reinforcement work is work aimed at restoring or improving strength. Say. However, repair work on civil engineering structures is a work that includes the purpose of restoring the proof stress because it is intended to return to the state before damage was received.
To explain the steel sheet winding method as an example, in the repair work, the injection device f is installed at the end of the crack d, and the repair material e is sealed with the sealing material g so that the repair material e does not leak from the side of the injection device f. Then, the pressurized repair material e is injected into the crack d (see the upper diagram in FIG. 6 or Patent Document 1).
Then, after the repair work is completed, a steel plate b is installed on the outer periphery of the concrete column a with a gap therebetween, and the gap between the concrete column a and the steel plate b is filled with a non-shrink mortar c or the like to complete the work (FIG. 6). (See the following figure, Patent Document 2 or Patent Document 3).
[0003]
[Patent Document 1]
Japanese Patent No. 2920806 [Patent Document 2]
JP-A-9-256327 [Patent Document 3]
JP-A-9-184303
[Problems to be solved by the invention]
The above-described conventional method for repairing a damaged concrete structure has the following problems.
<B> Renovation work will be completed by combining two works, repair work and reinforcement work. In particular, repair work requires work for each crack, and requires a lot of labor and time.
<B> In a situation where structures are damaged by an earthquake, traffic networks, lifelines, etc. are cut or threatened by the risk of collapse, it is desirable to recover as soon as possible as soon as possible. In order to deal with such cases, there is a need for a method that can perform renovation work in the shortest possible time.
[0005]
[Object of the invention]
The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a method for repairing a damaged concrete structure, which can be performed in a small number of steps and can greatly shorten the construction period.
It is another object of the present invention to provide a method for repairing a damaged concrete structure, which can reliably secure a target performance by a simple method.
The present invention achieves at least one of these objects.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for repairing a damaged concrete structure according to the present invention includes disposing an outer shell member with a gap from the damaged concrete structure, and filling the gap with a filler. This is a method for simultaneously filling the gap and filling the crack in the damaged portion. Here, the material and dimensions of the outer shell member can be determined based on the design shear strength, which is obtained by subtracting the load share of the unrepaired portion of the existing concrete structure, and the design toughness calculated based on the shear strength. Here, in the design, the unrepaired portion can be regarded as, for example, the inside (core portion) of the steel bar of the existing concrete structure.
When the outer shell member is used as a mold, it does not function as a structural member. Therefore, the material and dimensions of the outer shell member may be determined so as to withstand the filling pressure of the filler. In this case, since the outer shell formed by the filler is a structural member, the material of the filler and the dimensions of the gap for filling the filler are calculated by subtracting the load burden of the unrepaired portion of the existing concrete structure. Determined by the design shear strength and the design toughness factor calculated based on it.
Further, in the above-mentioned method for repairing a damaged concrete structure, the range of the unrepaired portion can be determined by the material of the filler. This is because the penetration performance for cracks differs depending on the material of the filler, and the range of the unrepaired portion also changes.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
<A> Application conditions The concrete structure 1 to which the present invention is applied is a structure made of reinforced concrete, steel reinforced concrete, prestressed concrete or unreinforced concrete.
Here, the degree of damage to which the present invention can be applied will be described by taking a reinforced concrete structure as an example.
Damage to reinforced concrete structures can be broadly divided into two stages. Shear damage stage and bending damage stage.
Here, the damage included in the shear damage stage is a shear damage (see FIG. 2) due to the occurrence of shear cracks and yielding of the belt reinforcing steel, and a shear damage after the axial reinforcing steel yielding. Here, FIG. 2A shows a state in which only horizontal cracks 51 have occurred, FIG. 2B shows a state in which the diagonal cracks 52 have not penetrated, and FIG. 2C shows a state in which the diagonal cracks 53 have penetrated. It shows the state that it is. These shear damages are within the scope of the present invention.
On the other hand, a bending damage stage in which bending damage occurs due to buckling or breakage of the axial rebar is outside the scope of the present invention. For example, the refining method of the present invention is not applied to the case where the cover concrete is largely separated, the reinforcing bar is protruding, or the axial reinforcing bar is broken and the frame is inclined.
Refurbishment may be limited to damaged parts and necessary parts only.
[0009]
<B> Outer Shell Member The outer shell member 2 is a member arranged on the outer periphery of the concrete structure 1 before the repair. The outer shell member 2 is installed at a distance from the damaged concrete structure 1.
As the outer shell member 2, a steel plate, a precast panel made of concrete, a continuous fiber sheet molded panel, a half precast panel in which a reinforcing bar or the like is projected to enhance the integration with the filler 3 described later, a wooden formwork, and the like are used. it can. The outer shell member 2 may function as a structural section or may not function as a structural section. For example, since a wooden form is released after being filled with a filler, it does not function as a structural section. The material and dimensions of the outer shell member 2 in this case may be determined so as to withstand the filling pressure of the filler 3.
When functioning as a structural section, as described later, the material and dimensions of the outer shell member 2 are determined by the design shear strength, which is obtained by subtracting the load share of the unrepaired portion of the existing concrete structure 1, and the design toughness calculated based on the shear strength. To determine.
The cross-sectional shape of the outer shell member 2 can be arbitrarily selected. For example, when the concrete structure 1 to be renovated is a column 1a or a beam having a rectangular cross-section, the outer shell member 2a having a U-shaped cross-sectional shape (FIG. )), An L-shaped outer shell member 2b (see FIG. 3B), and a square-shaped outer shell member (not shown). When only the beam portion of the beam 1b with slab is to be repaired, an outer shell member 2c having a U-shaped cross section that covers the beam portion from the outside (see FIG. 3C) can be employed. Further, in the case of repairing the columnar concrete structure 1, an outer shell member 2 having a semicircular, arc or annular cross section can be used.
[0010]
The separated outer shell members 2a and 2b can be joined by known joining means. For example, in order to join the outer shell members 2a and 2b made of a steel plate, a known welding method, a bolt method, a meshing method, and the like can be adopted.
In order to join the reinforced concrete outer shell members 2a and 2b, reinforcing bars projecting from the outer shell members 2a and 2b are joined by a known joint 41, and concrete is inserted into the gap 6 between the end faces of the outer shell members 2a and 2b. The joining portion 4 can be formed by casting a joining material such as (see FIGS. 3 and 1).
[0011]
<C> Filler Filler 3 is a material that fills gaps 6 and cracks between outer shell member 2 and concrete structure 1.
As the filler 3, a known material such as a resin-based material and a cement-based material, which has fluidity at the time of filling and solidifies after filling, can be used. Examples of the resin-based material include a foamed epoxy resin, an acrylic resin, an epoxy resin, a polyester resin, a urethane resin, and a silicone resin. The cement-based material includes a polymer cement-based slurry, an ultrafine cement-based slurry, a polymer cement mortar, a non-shrink mortar, and the like.
It is preferable to use a material having high permeability and fluidity, since the filler 3 is used not only to fill the gaps 6 but also to penetrate cracks. For example, foamed epoxy resin can penetrate into cracks due to expansion force, and acrylic resin is easily filled into cracks due to its high fluidity. Since the permeability differs depending on the material of the filler 3, the repair range also changes.
If the outer shell member 2 does not function as a structural cross section, the outer shell formed by the filler 3 is a structural member. Therefore, the material of the filler 3 and the dimensions of the gap 6 for filling the filler 3 will be described later. The design shear strength is calculated by subtracting the load share of the unrepaired part of the concrete structure, and the design toughness calculated based on the shear strength.
The filler 3 fills the gap 6 between the outer shell member 2 and the concrete structure 1 from the upper or lower gap 6 or the inlet. At this time, pressure injection can be performed by closing the space above the gap 6 if necessary.
[0012]
Hereinafter, an experiment on the performance of a structure repaired by the method for repairing a damaged concrete structure according to the present invention will be described with reference to the drawings.
[0013]
<A> Experimental conditions A constant axial force N of 19.6 kN was applied to a square pillar reinforced concrete specimen having a cross section of 500 mm × 500 mm and a height of 1550 mm, and positive and negative alternating loading P was performed. Here, the shear span is 1250 mm, and the shear span ratio is 2.5. In addition, experiments were performed on two specimens, a specimen having a maximum size of concrete aggregate of 10 mm (R10 specimen) and a specimen having a maximum dimension of 20 mm (R20 specimen).
[0014]
Then, the repair method of the present invention was applied to the R10 test piece and the R20 test piece that were subjected to shear failure.
The outer shell members 2 used in the experiment are outer shell members 2d and 2e made of lightweight mortar and having a square cross section with a thickness of 50 mm. An outer shell member 2d in which 13 mm (D13) reinforcing bars are arranged at 50 mm intervals at a distance of 20 mm from the base, and two outer shell members 2d having D13 reinforcing bars arranged at 100 mm intervals. Were arranged in two stages. Here, the outer shell member 2d is arranged at a distance of 20 mm from the base because the repair method of the present invention aims at shear reinforcement and toughness reinforcement and does not target bending reinforcement, so that bending strength is not improved. Like that.
As the filler 3, foamed epoxy resin was used for the damaged R10 specimen, and acrylic resin was used for the damaged R20 specimen.
[0015]
<B> Experimental results As a result of confirming the filling status of the foamed epoxy resin filled in the R10 specimen and the acrylic resin filled in the R20 specimen by coring, the foamed epoxy resin was cracked to a minimum of 0.45 mm. It was filled to a minimum of 0.25 mm of cracks. However, the crack inside the main rebar of the damaged specimen had a portion where the filler 3 was not filled (unrepaired portion). Therefore, when calculating the design toughness factor of the structure after rehabilitation, the concrete portion of the design shear strength is calculated by deducting the concrete portion of the core portion from the core inside the belt rebar as the unrepaired part. I did it.
[0016]
FIG. 5 (a) is a comparison diagram showing the relationship between the horizontal displacement P and the horizontal load P before and after the renovation of the R10 specimen by an envelope. FIG. 5B shows a similar comparison diagram for the R20 specimen.
From the results shown in FIG. 5, it can be seen that the repairing method of the present invention improves the proof stress after the repair compared to before the repair (before the damage). Also, regarding the deformation performance, it can be confirmed that the deformation performance after reaching the yield load was greatly improved. Here, the experimental results are shown in Table 1.
[0017]
[Table 1]

[0018]
The ultimate failure mode was shear failure for all specimens before rehabilitation, but bending failure after rehabilitation. Here, the determination of the type of fracture was made based on the state of cracks at the end of the operation and the strain of the strip reinforcing bars arranged in the outer shell members 2d and 2e.
In addition, the toughness of the specimen after renovation greatly exceeded the design toughness for the R10 specimen, and the toughness on the positive side slightly fell below the design toughness for the R20 specimen, but the toughness on the negative side was The result exceeded the toughness rate.
[0019]
The method for repairing a damaged concrete structure according to the present invention is not a method for completely repairing a crack, but a method for repairing a target performance in a simple manner by designing by previously subtracting an uncertain portion for crack repair. Can be secured. That is, when it is expected that there is a portion where cracks are not sufficiently repaired by the filler 3, design is performed by subtracting the portion, and when the performance is lower than the target, the material and dimensions of the outer shell member 2 or the filling The outer shell member 2 or the filler 3 is selected by increasing the strength by changing the material of the material 3 and the dimensions of the gap 6 filling the filler 3 and satisfying the proof stress required for the reconstructed structure. Design.
[0020]
【The invention's effect】
Since the method for repairing a damaged concrete structure according to the present invention is as described above, the following effects can be obtained.
<A> Since the conventional repair process can be omitted, the construction period can be greatly reduced. Further, even if the material cost of the filler increases, it is possible to obtain an economic effect by shortening the construction period.
<B> Since the design is performed without taking into account the proof stress of the part that is not sufficiently repaired, the target performance can be reliably ensured even if the repair is performed by a simple method.
[Brief description of the drawings]
FIG. 1 is an explanatory view of an embodiment of a method for repairing a damaged concrete structure according to the present invention.
FIG. 2 is an explanatory diagram showing a state of shear damage.
FIG. 3 is a plan view of the embodiment of the outer shell member.
FIG. 4 (a) is a plan view of a test piece used in an experiment. (B) Side view of the test specimen used in the experiment.
FIG. 5 (a) is a graph showing the relationship between horizontal displacement and horizontal load, showing experimental results of an R10 specimen. (A) The relationship diagram between the horizontal displacement and the horizontal load showing the test result of the R20 specimen.
FIG. 6 is an explanatory view showing a procedure of a conventional repair work and a reinforcing work.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Concrete structure 2 ... Outer shell member 3 ... Filler 6 ... Gap

Claims (4)

An outer shell member is placed with a gap from the damaged concrete structure,
By filling the gap with a filler, the filling of the gap and the filling of cracks in the damaged portion are simultaneously performed.
How to repair damaged concrete structures. The method for repairing a damaged concrete structure according to claim 1,
The material and dimensions of the outer shell member are determined by a design shear strength and a design toughness factor calculated based on the design shear strength after deducting a load share of an unrepaired part of an existing concrete structure,
How to repair damaged concrete structures. In the method for repairing a damaged concrete structure according to claim 1 or 2, the material of the filler and the size of the gap for filling the filler are less the load share of the unrepaired portion of the existing concrete structure. It is determined by the design shear strength and the design toughness factor calculated based on it,
How to repair damaged concrete structures. The method for repairing a damaged concrete structure according to claim 2 or 3, wherein a range of the unrepaired portion is determined by a material of the filler.
How to repair damaged concrete structures.

Images