JPH09183182A - Reinforced structure of concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the shear fracture from generating by a method wherein on the surface of a concrete structure, a molten resin under a state containing a reinforcing agent is jetted, and tightly joined to form a reinforcing plastic layer. SOLUTION: On the surface of a contrete pole main body (1a), a reinforcing plastic layer 2 is formed. The reinforcing plastic layer 2 is favorably joined and bonded on the concrete structure (1a) with an adhesive layer 21, and at the same time, a reinforcing layer 20 favorably displays the function mainly as a coating member and a reinforcing member, and also, the surface is finished with a finishing layer 22. The reinforcing layer 20 is formed in such a manner that a roving 4 which is being cut into a chop strand reinforcing material 4a, is jetted together with a molten resin 5 by a spray gun 3 of a spray-up device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing structure for a concrete structure.

[0002]

2. Description of the Related Art In recent years, it has been proposed to reinforce existing concrete columns laid on railways, roads and the like in order to reduce damage caused by earthquakes. Known examples of this type of reinforcing structure include a steel plate reinforcing structure and a fiber reinforced plastic (FRP) plate reinforcing structure.
The steel plate reinforcement structure covers the outer periphery of the concrete column with a steel plate in a tubular shape, and the yield load of the existing concrete column,
It is said that bending toughness and shear strength can be improved.

On the other hand, the FRP plate reinforcing structure is shown in FIGS.
The FRP plate shown in is used. The FRP plate 50 is preformed to have a rectangular shape, and ribs 51 project from the inner surface of the FRP plate 50 so as to have a lattice shape. The plurality of FRP plates 50 are brought into close contact with the outer periphery of the concrete column with the ribs 51 inside, and the adjacent FRP plates 50 are joined together. For example, the adjacent FRP plates 50 are heated and melted on the joint surface of the FRP plates 50, and in this state, the molten resin is supplied from the extrusion molding machine and welded and joined. After that, the FRP plate 50
Mortar is injected through the through hole formed in the FRP plate 50.
The FRP plate 50 and the concrete columns are bonded together via the ribs 51 while filling the gap between the FRP plate 50 and the concrete columns.
According to such an FRP plate reinforcing structure, it is said that the shear strength and bending toughness of an existing concrete column can be improved.

However, among the conventional reinforcing structures for concrete structures, the steel plate reinforcing structure is
Since a steel plate, which is a heavy object, is handled, a mechanical work such as a crane is required, and thus it is necessary to secure a required work space. Further, in the FRP plate reinforcing structure, a plurality of lightweight FRP plates 50 are joined. Therefore, the work in a narrow space is relatively easy, but stress concentrates on the joint between the FRP plates 50, and the FRP plates 50 are easily broken. When a bending test was performed on a concrete column having this FRP plate reinforced structure, it was fractured in a shape similar to the shear fracture of the concrete column, and oblique tensile fracture occurred at the joint portion of the plurality of FRP plates 50. The yield strength after the oblique tensile rupture occurred at the joint portion of the FRP plate 50 sharply decreased. Therefore,
The improvement of shear strength and bending toughness of concrete columns cannot be said to be sufficient.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional technical problems, and has the following configuration. The structure of the invention of claim 1 is characterized in that a reinforced plastic layer 2 is formed by spraying a molten resin 5 onto the surface of a concrete structure 1a in a state of containing a reinforcing material 4a for close contact. It is a reinforced structure for objects. The structure according to claim 2, wherein the reinforced plastic layer 2 is an adhesive layer 21 made of only a resin that is tightly joined to the concrete structure 1a, and a reinforced layer made of a resin and a reinforcing material 4a that is tightly joined to the adhesive layer 21. 20 and
The reinforcing structure for a concrete structure according to claim 1, further comprising: a finishing layer (22) made of only a resin, which is adhered and bonded onto the reinforcing layer (20). The structure of claim 3 is characterized in that the woven fabric 7 is arranged on the surface of the stress concentration portion of the concrete structure 1a, and the reinforced plastic layer 2 is formed on the surfaces of the concrete structure 1a and the woven fabric 7.
Or, it is a reinforced structure of the concrete structure of 2. According to the structure of claim 4, the end portion of the reinforced plastic layer 2 is attached to the band 6
The reinforcing structure for a concrete structure according to claim 1, 2 or 3, wherein the structure is tightened by a and 6b.

[0006]

According to the invention of claim 1, the reinforced plastic layer 2 improves the bending toughness of the concrete structure 1a,
Prevent shear failure. That is, according to the concrete structure 1a in which the reinforced plastic layer 2 is formed, the reinforced plastic layer 2 exhibits excellent functions as a covering member and a strength member, the destruction of the concrete structure 1a is suppressed, and the concrete structure is The concrete, which is the main component of the object 1a, favorably supports the compressive force. Moreover,
Since the reinforced plastic layer 2 is formed seamlessly,
No discontinuous portions are formed, and it is difficult for stress concentration portions to be formed on the reinforced plastic layer 2 itself. As a result, it is possible to prevent deterioration of the reinforcing layer due to local breakage of the reinforced plastic layer 2 and eventually deterioration of the earthquake resistance of the concrete structure 1a.

When the concrete structure 1a is a concrete column, it is effective to improve bending toughness in order to improve seismic resistance by reinforcing the concrete column, and when the yield load is increased, the boundary with the non-reinforced portion is increased. This is not desirable because it causes early destruction in some parts. On the other hand, according to the concrete column formed with the reinforced plastic layer 2,
Flexural toughness can be improved with almost no increase in yield load, which is the load for cracking of concrete.
That is, the initial rigidity of the concrete column with the reinforced plastic layer 2 is almost equivalent to that of the non-reinforced concrete column, and even if the reinforced plastic layer 2 is used for reinforcement against earthquakes, the reinforced plastic layer 2 will have an excessive cross section during an earthquake. Hard to generate force. It is presumed that this is because the reinforced plastic layer 2 has appropriate and good elongation characteristics as compared with the structure 1a made of a concrete column.

According to claim 2, the reinforced plastic layer 2
However, the adhesive layer 21 makes a good close contact with the concrete structure 1a, and mainly the reinforcing layer 20 exerts a good function as a covering member and a strength member.
The surface is finished by the finishing layer 22.

According to the third aspect of the invention, the reinforcing function of the reinforced plastic layer 2 is enhanced by the fabric 7.
The stress concentration points of the concrete structure 1a on which the woven fabric 7 is arranged are points having a small wall thickness, points receiving a large bending deformation, and the like. Therefore, when the concrete structure 1a is a quadrangular prism, it is a corner portion of the concrete column, a central portion in the longitudinal direction, or the like.

According to claim 4, the reinforced plastic layer 2
It is possible to prevent a gap from being formed between the end of the concrete structure 1a and the concrete structure 1a due to a change with time. As a result, rainwater or the like intrudes through the gap, and the peeling of the reinforced plastic layer 2 gradually progresses, and the peeling of the reinforced plastic layer 2 in a wide range is well prevented.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 show an embodiment of a reinforcing structure for a concrete structure according to the present invention. In the drawing, reference numeral 1 denotes a concrete column as a concrete structure, and an existing concrete column main body 1 laid vertically on a railway track including a highway, a subway, and the like.
a is mainly used. That is, the concrete pillar 1 is composed of an existing concrete pillar body 1a standing on the foundation 10 and supporting the floor slab 11, and a reinforced plastic layer 2 formed on the surface of the concrete pillar body 1a. The existing concrete column main body 1a is usually manufactured by reinforced concrete (RC), and has a structure in which a strip reinforcing bar 1c is wound around the main reinforcing bar 1b as shown in FIG. In the figure, the concrete pillar main body 1a is a square pillar, but may be a cylinder or the like.

The reinforced plastic layer 2 is mainly composed of a reinforced layer 20 formed by a spray-up method as shown in FIG. 3 for the purpose of reinforcing the concrete column main body 1a.
That is, the reinforced plastic layer 2 is an adhesive layer 21 made of only a resin that is adhered and joined onto the concrete column main body 1a.
And a reinforcing layer 20 made of a resin containing the chopped strand reinforcing material 4a in close contact with the adhesive layer 21, and a finishing layer 2 made of only the resin in close contact with the reinforcing layer 20.
2 and 2 in a laminated state.

The adhesive layer 21 has a function of firmly adhering the reinforcing layer 20 to the concrete column main body 1a, and the spray gun 3 to the roving 4 of the spray-up apparatus shown in FIG.
The molten resin 5 is sprayed to a predetermined thickness without being supplied. The surface of the concrete column main body 1a is subjected to a mechanical or chemical surface treatment in order to strengthen the joint. In this mechanical surface treatment, the surface of the concrete column main body 1a is roughened with a wire brush,
This is performed by forming innumerable concave portions having a size of less than or equal to μm, preferably several tens of μm in advance.

The reinforcing layer 20 mainly has a function of reinforcing the concrete column main body 1a, and is formed by spraying the roving 4 together with the molten resin 5 while cutting the roving 4 into the chopped strand reinforcing material 4a by the spray gun 3 of the spray-up device. To do. The chopped strand reinforcing material 4a is obtained by cutting the roving 4 made of glass fiber into about 20 to 30 mm (preferably about 25 mm) with a chopper, and the content rate is 20 to 30% by volume. The thickness of the reinforcing layer 20 depends on the shape and size of the concrete column body 1a, but the existing concrete column body 1
When the purpose is to improve the earthquake resistance of a, the average is 3 to 8
A thickness of about 5 mm is required, and an average of about 5 mm is desirable.
If the reinforced layer 20 is thicker than about 5 mm on average, the reinforcing function is increased but the cost is increased. Finishing layer 22
Mainly has a function of enhancing the appearance, and is formed by spraying only the molten resin 5 to a predetermined thickness without supplying the roving 4 from the spray gun 3.

As the resin used for the adhesive layer 21, the reinforcing layer 20 and the finishing layer 22 of the reinforced plastic layer 2, so-called drooling phenomenon hardly occurs, the time required for curing is relatively short, and it has room temperature curability. Desirably, an appropriate resin material is blended in consideration of the temperature environment of the work place. Whose phenomenon is a defect in which, when a molten resin is sprayed on a vertical surface, the resin partially collects due to its own weight to form a droplet, and includes a defect in which the resin flows downward due to its own weight. The types of the molten resin 5 forming the adhesive layer 21, the reinforcing layer 20, and the finishing layer 22 are
Each can be different. In addition, fire resistance can be improved if a resin such as a flame retardant is added as the molten resin 5 forming at least the finishing layer 22.

Next, the operation will be described. According to the concrete pillar 1 in which the reinforced plastic layer 2 is formed on the existing concrete pillar body 1a, the reinforced plastic layer 2 improves the bending toughness of the existing concrete pillar body 1a,
Prevent shear failure. The bending test shown in FIG. 4 was performed.
That is, the lower ends of both ends of the concrete column 1 are supported by fulcrums 30 and 31, respectively, and the load W is applied from the two load points 32 and 33 via the loading beam 34 arranged in the central upper part.

When a bending test was performed on the concrete column 1, it was confirmed that the concrete column 1 having the reinforced plastic layer 2 formed thereon exerts a good tensile force on the main rebar 1b by the action of the reinforced plastic layer 2. In addition, the concrete compression generated in the concave reverse bending section is well supported. This is a reinforced plastic layer 2
Among them, mainly the strengthening layer 20 satisfactorily exerts the functions as a covering member and a strength member, cracking and destruction of the concrete column main body 1a is suppressed, and the concrete column main body 1a is suppressed.
It is estimated that the result is that the compressive force is favorably supported by the concrete, which is the main component of

Moreover, since the reinforced plastic layer 2 is formed uniformly by the spray-up method without a seam, discontinuous portions are not formed and stress-concentrated portions are not easily formed in the reinforced plastic layer 2 itself. As a result, local oblique tensile rupture of the reinforced plastic layer 2 is unlikely to occur, and thus the seismic resistance of the concrete column body 1a can be prevented from prematurely degrading.

The test results are shown in FIG. The solid line I shows the characteristics of the concrete column 1 on which the reinforced plastic layer 2 is formed, and the chain double-dashed line II shows the characteristics of only the existing concrete column body 1a on which the reinforced plastic layer 2 is not formed. In the concrete pillar 1 on which the reinforced plastic layer 2 is formed,
The main reinforcing bar 1b yielded at the point (a) after the strip reinforcing bar 1c yielded, but the load W increased thereafter. After that, at the point (b), fracture started in the convex pure bending section of the reinforced plastic layer 2, and the fracture portion A shown in FIG. The fracture of the reinforced plastic layer 2 in the pure bending section having the convex shape at the point (c) was completed, and the load W gradually decreased. Then, in the area shown in (d), the load W
The yield strength was such that the central deflection of the concrete column 1 increased with almost no change, and the concrete in the pure bending section broke at the point (e), so the load W was unloaded.

Thus, the existing concrete pillar body 1
Concrete pillar 1 with reinforced plastic layer 2 formed on a
According to this, the load W increases up to the point (c) at which the breakage of the reinforced plastic layer 2 in the pure bending section shown in FIG. 5 ends, and the concrete pillar body 1a in the area shown in (d).
The increase of the central deflection is remarkable while maintaining the proof stress.
This is because, as described above, the reinforced layer 20 of the reinforced plastic layer 2 mainly functions as a covering member and a strength member, and early yielding accompanied by shearing of the strip reinforcing bar 1c and the main reinforcing bar 1b and the concrete column main body 1a. It is presumed that this is because the early yielding accompanied by shear that causes crack fracture is prevented, and as a result, the compressive force is favorably supported by the concrete, which is the main component of the concrete column main body 1a. More specifically, the cracks in the concrete are restrained by the reinforced plastic layer 2, and it becomes difficult for the reinforcing bar 1c and the main reinforcing bar 1b and the concrete to be sheared along the broken line N shown in FIG. It is presumed that this is because the tensile strength of 1b apparently increases. Thus, according to the reinforced plastic layer 2, it is possible to improve the bending toughness of the concrete column 1.

By the way, in the characteristics of the existing concrete column main body 1a only, in which the reinforced plastic layer 2 is not formed, the reinforcing action as the covering member and the strength member by the reinforced plastic layer 2 is not expected, and the concrete column main body 1a is shown in FIG. As shown by the broken line N, a shearing force acts along a line connecting each load point 32, 33 and the corresponding fulcrum 30, 31,
After yielding of the reinforcing bar 1c, the main reinforcing bar 1b was shear fractured together with the concrete, and the yield strength was lost. Thus, in the case of an existing concrete column in which the reinforced plastic layer 2 is not formed, the strip reinforcing bar 1c and the main reinforcing bar 1b are fractured, the tensile strength is lowered at an early stage, and the central deflection of the concrete column main body 1a is not increased. Concrete is destroyed. Point (f) in FIG. 5 shows the time point at which shear failure occurs in the existing concrete column main body 1a on which the reinforced plastic layer 2 is not formed, and the load was removed after the shear failure occurred.

In this way, according to the concrete column 1 having the reinforced plastic layer 2 formed therein, the fracture of the concrete column body 1a and the reinforced plastic layer 2 due to the earthquake can be obtained as a bending fracture state, and the concrete column 1 The ultimate failure of the concrete will be determined by the crack failure of the concrete in the pure bending section. Then, in order to improve the earthquake resistance by reinforcing the existing concrete column main body 1a, it is effective to improve the bending toughness, and for example, in order to suppress shear failure along the broken line N shown in FIG. It is not desirable to cover the outer circumference of No. 1 in a tubular shape with a steel plate to increase the yield load, because it will cause early fracture at the boundary with the non-reinforced portion. On the other hand, according to the concrete column 1 in which the reinforced plastic layer 2 is formed, the bending toughness can be improved without increasing the yield load.

Further, the initial rigidity of the concrete column 1 on which the reinforced plastic layer 2 is formed is almost equivalent to that of the existing unreinforced concrete column body 1a, and even if the reinforced plastic layer 2 is reinforced against earthquakes, an earthquake will occur. At times, an excessive cross-sectional force acts on the reinforced plastic layer 2 at an early stage, so that the reinforced plastic layer 2 does not break. This includes the reinforced plastic layer 2, that is, the adhesive layer 21 and the finishing layer 22 made of resin, as well as the chopped strand reinforcing material 4 made of glass fiber.
The reinforcing layer 20 made of a resin containing a also has a smaller elastic modulus than concrete, and therefore the concrete column main body 1a
This is a result having moderate and good elongation characteristics as compared with.

As shown in FIG. 6, the adhesive layer 21 and the finishing layer 22 are omitted and the reinforced plastic layer 2 is replaced with the reinforced layer 20.
Even if it is formed only by itself, it is possible to obtain almost the same action with respect to the improvement of the earthquake resistance. When a thermosetting resin is used as the molten resin 5 to improve the fire resistance, the reinforced plastic layer 2 is seamlessly formed by the spray-up method, and separate FRP plates such as an FRP plate reinforced structure are separately provided. Since no joining work is required, it does not require a difficult melt bonding work.

FIG. 7 shows an example of a structure in which the upper and lower ends of the reinforced plastic layer 2 are fastened with bands 6a and 6b. The end portion of the reinforced plastic layer 2 tends to form a gap with the concrete column main body 1a due to aging. The bands 6a and 6b suppress the formation of a gap between the reinforced plastic layer 2 and the concrete column main body 1a, rainwater and the like enter through the gap, and the peeling of the reinforced plastic layer 2 gradually progresses. Good prevention of peeling of the reinforced plastic layer 2 in a wide range.

Further, as shown in FIG. 8, a woven fabric 7 made of the same material (glass fiber) as the chopped strand reinforcing material 4a is arranged on the surface of the stress-concentrated portion of the existing concrete column body 1a, It is also possible to form the reinforced plastic layer 2 on the surfaces of the la and the fabric 7. As the stress concentration points of the existing concrete pillar 1 on which the woven fabric 7 is arranged, there are a point where the wall thickness of the concrete pillar main body 1a is thin, a point where a large amount of bending deformation is received, and the like. Therefore, in the case of the concrete pillar main body 1a forming a square pillar,
The corner portion of the concrete column main body 1a, the central portion in the longitudinal direction, and the like. Thereby, the reinforced layer 20 of the reinforced plastic layer 2
The reinforcing function of the fabric 7 is enhanced by the fabric 7. In addition,
The woven fabric 7 may be interposed between the adhesive layer 21 and the reinforcing layer 20.

By the way, in the above-described embodiment, the concrete pillar main body 1a already installed as a concrete structure is used.
I explained about the reinforced plastic layer 2 on the surface of concrete such as walls of general buildings, moss, tunnels and beams.
It is also possible to reinforce the concrete by applying. Further, in order to prevent the collapse of the moss, it is possible to form the reinforced plastic layer 2 directly on the surface of the debris of the moss without laying concrete. Furthermore, in order to improve the weather resistance and fire resistance of the reinforced plastic layer 2,
It is also possible to wind or spray the surface with insulation.

As a method of forming the reinforced plastic layer 2 on the surface of the concrete structure 1a, a hand layup method can be applied. In particular, a reinforcing material alone or a reinforcing material preliminarily impregnated with a resin is arranged in a long length in the longitudinal direction of the surface of an existing concrete column main body 1a, and a molten resin 5 is sprayed from above the reinforcing material 4a for close contact bonding. By doing so, it is also possible to align the extending directions of the reinforcing materials, improve the bending toughness of the existing concrete column main body 1a and other structures, and effectively prevent shear failure.

[0029]

As will be understood from the above description,
According to the reinforcing structure for a concrete structure according to the present invention,
It is possible to form a reinforced plastic layer uniformly without being restricted by the shape of the concrete structure,
A concrete structure can be simply, stably and effectively reinforced. As a result, mechanically, the damage resistance of the concrete structure can be improved to improve the earthquake resistance and shock resistance, and the surface coating action prevents the deterioration of the concrete structure and improves the durability. Can be made. In addition, the reinforced plastic layer is easy to repair,
It is possible to easily repair the damaged part that has occurred in part.
According to the second aspect, the reinforced plastic layer having the finishing layer can improve the appearance and feel of the concrete structure.

[Brief description of the drawings]

FIG. 1 is a view showing a concrete pillar reinforcing structure according to an embodiment of the present invention with a part thereof omitted.

FIG. 2 is a sectional view showing the same concrete pillar.

FIG. 3 is a sectional view showing an important part of the concrete pillar.

FIG. 4 is an explanatory view showing a bending test of a concrete column.

FIG. 5 is a diagram showing a center deflection-load characteristic of a concrete column which is also the result of a bending test of the concrete column.

FIG. 6 is a sectional view showing a main part of a concrete column in which a reinforced plastic layer is also formed only by a reinforced layer.

FIG. 7 is a view omitting a part of a structural example of a reinforcing structure of a concrete column in which both upper and lower ends of a reinforced plastic layer are similarly tightened with bands.

FIG. 8 is a view showing a structure example in which a woven fabric is arranged on the surface of a stress concentration portion of the concrete column main body while omitting a part thereof.

FIG. 9 is a front view showing a conventional FRP plate with a part thereof omitted.

FIG. 10 is a side view showing the FRP plate with a part thereof omitted.

[Explanation of symbols]

1: concrete column, 1a: concrete column body (concrete structure), 2: reinforced plastic layer, 4a: chopped strand reinforcing material (reinforcing material), 5: molten resin,
6a, 6b: band, 7: fabric, 20: reinforcing layer, 21:
Adhesive layer, 22: finishing layer.

Front Page Continuation (72) Inventor Shinji Kusunoki 1-1 Nikko-cho, Fuchu-shi, Tokyo Inside Nihon Steel Works (72) Inventor Toshio Hayashi 2-3-5 Misaki-cho, Chiyoda-ku, Tokyo Steel Construction Co., Ltd. In-house (72) Inventor Takuo Moriya 2-5-3 Misaki-cho, Chiyoda-ku, Tokyo Iron Construction Co., Ltd. (72) In-house Masaharu Saito 2-3-5 Misaki-machi, Chiyoda-ku, Tokyo Iron-Construction Construction Co., Ltd. In-house (72) Inventor Shigeru Matsuoka 2-5-3 Misaki-cho, Chiyoda-ku, Tokyo Inside Tetsuken Construction Co., Ltd.

Claims (4)

[Claims] 1. A surface of a concrete structure (1a),
A reinforcing structure for a concrete structure, characterized in that a reinforced plastic layer (2) is formed by spraying a molten resin (5) in a state of containing a reinforcing material (4a) and closely bonding the molten resin (5). 2. A reinforced plastic layer (2), an adhesive layer (21) consisting only of a resin that is intimately bonded onto a concrete structure (1a), and a resin and a reinforcement that are intimately bonded onto an adhesive layer (21). A reinforcing layer (20) made of the material (4a),
The reinforcing structure for a concrete structure according to claim 1, further comprising a finishing layer (22) made of only a resin, which is closely bonded to the reinforcing layer (20). 3. A woven fabric (7) is arranged on the surface of a stress concentration portion of the concrete structure (1a), and a reinforced plastic layer (2) is formed on the surfaces of the concrete structure (1a) and the woven fabric (7). The reinforcing structure for a concrete structure according to claim 1 or 2, wherein 4. The reinforcing structure for a concrete structure according to claim 1, wherein the ends of the reinforced plastic layer (2) are tightened by bands (6a, 6b).