JP2004052310A - Reinforcing construction method of existing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To economically reinforce an existing structure while avoiding the diversification of a process and an increase in labor. <P>SOLUTION: This reinforcing construction method integrally joins a reinforcing material 12 to a bridge pier 10 by arranging the reinforcing material 12 over the whole outside surface of the bridge pier 10. The reinforcing material 12 is composed of a highly tough cement board 14 and a fiber sheet for alternately joining the board 14. The board 14 has characteristics of a flexural strength of 30 MPa or higher, a span of 18 cm and a maximum deflection of 25 mm or larger. When reinforcing the bridge pier 10, the board 14 is arranged on the surface side of the bridge pier 10. Afterwards, a curing material 28 such as mortar is placed in an interval 18, and this material is cured, and the board 14 is integrated to the surface of the bridge pier 10. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for reinforcing an existing structure, and more particularly to a method for reinforcing a high-toughness cement board as a reinforcing material.
[0002]
[Prior art]
Existing concrete structures, for example, piers of road bridges and railway bridges, or floor slabs are sometimes reinforced for the purpose of improving earthquake resistance and bending resistance. In addition, existing concrete structures may be rehabilitated for the above-mentioned purpose at the same time as repairing aging due to salt damage and neutralization.
[0003]
Conventionally, as a method used for such reinforcement, there are a method of increasing the cross-section of an existing structure with concrete or mortar, a method of increasing the cross-section, a method of rolling a steel sheet around the surface of the existing structure, and the like. The reinforcement method had the following technical problems.
[0004]
[Problems to be solved by the invention]
In other words, in the case of the cross-section thickening method, the required performance may be satisfied without the use of reinforcing bars, but if the bending strength or shear strength is intended to be increased, the reinforcing bars must be assembled. In addition, installation and removal of concrete or mortar setting dams, and further curing of concrete or mortar are required, resulting in a problem that the process is diversified and the construction period becomes long.
[0005]
Further, in this method, the weight of the structure increases due to the increase in the cross-section of the structure, so that the foundation may need to be reinforced.
[0006]
On the other hand, in the case of the steel sheet winding method, since the weight of the steel sheet is large, a large amount of labor is required for winding, and since the steel sheet is easily corroded, it is necessary to perform anticorrosion coating, especially in the case of salt damage. Has a high anticorrosion grade, and the construction method is expensive.
[0007]
The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an existing structure that can be economically reinforced while avoiding diversification of processes and an increase in labor. An object of the present invention is to provide a method for reinforcing objects.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for reinforcing an existing structure, wherein a reinforcing material is disposed on a surface of the existing structure, and the reinforcing material is integrally connected to the existing structure. As the material, a high-toughness cement boat having a bending strength of 30 MPa or more, a span of 18 cm, and a maximum deflection of 25 mm or more was used.
[0009]
According to the reinforcing method for an existing structure configured as described above, the high toughness and shear strength of the high-toughness cement board enable bending and shear reinforcement of the existing structure. In addition, since the high toughness cement board is lighter than a steel plate, the labor required for erection is less than that of a steel plate winding method, and it is economical.
[0010]
Furthermore, the high-toughness cement board is used as a buried formwork that also serves as a weir plate when casting mortar, etc., so dismantling of the weir plate is not necessary and the curing period is not required. The number of processes and processes is reduced as compared with, and it becomes economical.
[0011]
The high-toughness cement board may be preliminarily coated on its back side with a water-absorbing regulator for regulating water absorption.
[0012]
According to this configuration, since the water absorption adjusting agent is applied to the back side of the high toughness cement board, when a hardening material such as concrete or mortar is poured, water absorption from the hardening material is suppressed, Inconveniences such as a decrease in adhesion and bending strength due to excessive water absorption can be avoided.
[0013]
In this case, a water-soluble liquid containing ethylene-vinyl acetate copolymer emulsion as a main component can be used as the water absorption adjusting agent. This aqueous solution is diluted at a predetermined dilution ratio and applied to a high-toughness cement board.
[0014]
In the high toughness cement board, in the manufacturing process, when dewatering by pressing, it is possible to form an uneven portion having a height of about 1 mm and an interval of about 1 to 2 mm by sandwiching an uneven forming member such as a wire mesh. it can.
[0015]
According to this configuration, the adhesive force between the high-toughness cement board and the curable material can be enhanced.
[0016]
The high-toughness cement board is formed in a rectangular shape having a predetermined length and a predetermined thickness, and when installing a plurality of the high-toughness cement boards on the outer periphery of the existing structure, a gap between the adjacent high-toughness cement boards is provided. It can be joined with a carbon fiber or aramid fiber sheet.
[0017]
The high-toughness cement board is disposed at a predetermined distance from the surface of the existing structure, and by filling a hardening material such as concrete or mortar in the space, and hardening the hardening material, It can be integrated with the existing structure.
[0018]
The high-toughness cement board is supported at one end by an anchor embedded in the existing structure so as to provide the space, and after arranging a reinforcing steel material such as a reinforcing bar or a PC strand in the space, the hardening is performed. Material can be filled.
This configuration is adopted when the reinforcing effect of the existing structure is insufficient with only the high-toughness cement board, but even in this case, due to the durability of the cement board, the covering amount of the hardening material such as mortar is reduced. be able to.
[0019]
Further, in the present invention, the high toughness cement board is installed adjacent to the surface of the existing structure, from the surface side of the high toughness cement board, injects a curable resin, and by curing the curable resin, It can be integrated with existing structures.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show a first embodiment of a method for reinforcing an existing structure according to the present invention.
[0021]
FIG. 1 shows a completed construction state when the reinforcing method of the present embodiment is applied to a pier 10 as an existing structure. In the reinforcing method according to the present embodiment, a reinforcing member 12 is provided over the entire outer surface of the pier 10 (existing structure), and the reinforcing member 12 is integrally connected to the pier 10.
[0022]
The reinforcing material 12 includes a high-toughness cement board 14 and a fiber sheet 16 that joins the high-toughness cement board 14 to each other. The high-toughness cement board 14 is also used as a weir plate that separates a casting area when a hardening material such as concrete, mortar, or resin mortar is cast on the back side thereof. It is formed in a rectangular flat plate having a side length of 900 mm and a long side length of about 1800 mm.
[0023]
The high toughness cement board 14 of the present embodiment has a performance of a flexural strength of 30 MPa or more, a span of 18 cm, and a maximum deflection of 25 mm or more. Such a high-toughness cement boat 14 has a predetermined thickness, for example, a thickness of about 10 mm, mainly composed of cement, and has two-dimensionally random reinforcing fibers (PVA fibers having excellent alkali resistance) in a cement matrix. It is oriented.
[0024]
Such a high toughness cement board 14 has, for example, a compounding ratio of 3% by weight of reinforcing fiber, 60 to 95% by weight of ordinary cement, 0 to 35% by weight of inorganic minerals, and 2 to 2% of other admixtures. It is configured to contain 3% by weight.
[0025]
For example, if the thickness is 6 mm, the high toughness cement board 14 having such a mixing ratio has a performance of a bending strength of 33 MPa, a tensile strength of 15 MPa, and a bending displacement of 22 mm, and has the same performance as aluminum. I have.
[0026]
Further, in the high-toughness cement board 14 of the present embodiment, during press dewatering in the manufacturing process, the unevenness forming member such as a wire mesh is sandwiched, so that the unevenness having a height of about 1 mm and an interval of about 1 to 2 mm is provided. It is desirable to form a part. By providing such an uneven portion, the adhesive force between the high-toughness cement board 14 and the curable material can be enhanced.
[0027]
On the other hand, the fiber sheet 16 is formed, for example, by arranging long fibers made of carbon fibers or aramid fibers in the longitudinal direction to form a predetermined width, and as shown in FIG. The plurality of high-toughness cement boards 14 are bonded and fixed so as to straddle between the joining ends of the high-toughness cement boards 14 arranged adjacent to each other.
[0028]
When reinforcing the pier 10, first, a number of high toughness cement boards 14 are used and disposed on the surface side of the pier 10. In this case, as shown in FIG. 3, the high toughness cement board 14 is supported by the anchor 20 at a predetermined distance 18 (for example, about 30 mm) from the surface of the pier 10.
[0029]
The high-toughness cement board 14 is arranged so as to cover the entire surface of the pier 10, and the bonding between the boards 14 is performed from the front side of the board 14 by bonding the fiber sheet 16.
[0030]
At this time, a shoring 22 is arranged on the surface side of the high-toughness cement board 14 to prevent misalignment thereof. One end of the anchor 20 is embedded in the bridge pier 10, and the cement board 14 is locked to the other end.
If the surface of the pier 10 is damaged by, for example, salt damage, a process of removing the damaged portion and shaping the surface are performed before the high-toughness cement board 14 is installed.
[0031]
Further, when reinforcing steel materials 24 such as reinforcing bars and PC strands are installed in the space 18, these reinforcing steel materials 24 are assembled before the high-toughness cement board 14 is arranged. Such a reinforcing steel material 24 is employed when the reinforcing effect of the existing structure is insufficient with only the high-toughness cement board 14. However, even in this case, due to the durability of the cement board 14, a hardening material such as mortar is used. 28 can be reduced.
[0032]
Further, in the case of the present embodiment, before being attached to the outer periphery of the pier 10, a water absorption adjusting agent 26 for restricting water absorption is applied to the high toughness cement board 14 before it is assembled on the outer periphery of the pier 10.
[0033]
When the hardening material 28 such as concrete or mortar is cast on the back side of the high-toughness cement board 14, the water-absorbing adjuster 26 suppresses water absorption from the hardening material 28, resulting in excessive water absorption. It is applied to avoid inconveniences such as a decrease in adhesive strength and bending strength.
[0034]
In this case, the water absorption adjusting agent 26 can be a water-soluble liquid containing an ethylene-vinyl acetate copolymer emulsion as a main component. The aqueous solution is diluted at a predetermined dilution ratio and applied to a high-toughness cement board. For such an aqueous solution, for example, Hilex (trade name, manufactured by Nippon Kasei Co., Ltd.) can be used.
[0035]
When the high-toughness cement board 14 is disposed on the outer periphery of the pier 10, a hardening material 28 such as concrete or mortar is poured into the space 18, and the hardening material 28 is hardened, so that the high-toughness cement board 14 is hardened. 14 is integrated with the outer surface of the pier 10, and the reinforcement work is completed.
[0036]
In this case, the high toughness cement board 14 functions as a weir plate when the hardening material 28 is cast. At this time, since the cement board 14 has high toughness, it can be formed with a predetermined curvature when manufacturing the cement board.
[0037]
Now, according to the reinforcing method for the existing structure configured as described above, the high toughness and shear strength of the high-toughness cement board 14 enable the bending and shear reinforcement of the pier 10 (the existing structure).
[0038]
Further, since the high toughness cement board 14 is lighter in weight than a steel plate, the labor for erection is reduced compared to the steel plate winding method, and it is economical. Furthermore, the high-toughness cement board 14 becomes a buried formwork that also serves as a weir plate when casting mortar or the like, so that dismantling of the weir plate becomes unnecessary, and a curing period is not required. Compared with the construction method, the number of construction steps and processes are reduced, and it becomes more economical.
[0039]
In the case of the present embodiment, when the high-toughness cement board 14 is used as an embedding formwork, is structurally integrated with a hardening material 28 such as concrete, and when the cement board 14 is used as a tensile material, it is difficult to use the cement board 14 at a joint. Transmission of the tensile force is performed via the fiber sheet 16.
[0040]
In this case, if a carbon fiber sheet is adopted as the fiber sheet 16, its tensile strength is a high-strength material of 5000 N / mm ^{2. When} such a sheet is bonded to the joint, the tensile force can be sufficiently transmitted. it can. Since the compressive force can be transmitted directly by contact between the boards 14, even if the fiber sheet 16 does not have rigidity, the fiber sheet 16 functions sufficiently as a joint.
[0041]
FIG. 4 shows a second embodiment of the method of reinforcing an existing structure according to the present invention. The same or corresponding parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Only the characteristic points will be described.
[0042]
In the reinforcing method shown in the figure, a high-toughness cement board 14 and a fiber sheet 16 are used as the reinforcing material 12 of the pier 10 as in the first embodiment. The high-toughness cement board 14 is installed adjacent to the surface of the pier 10 without providing the space 18 as in the first embodiment.
[0043]
An anchor 20 similar to the above embodiment is used for installing the high-toughness cement board 14. When the setting of the high-toughness cement board 14 is completed, the curable resin 30 is injected from the front side of the high-toughness cement board 14, and the hardening resin 30 is hardened on the back side of the cement board 14, thereby setting the cement. The board 14 is integrated with the pier 10.
[0044]
The curable resin 30 is injected into the back side of the high-toughness cement board 14 from an injection hole 32 previously drilled at an appropriate position.
[0045]
The same operation and effect as in the above embodiment can be obtained by the reinforcing method configured as described above. In addition, in the said Example, the case where this invention was applied to reinforcement of the pier 10 as an existing structure was illustrated, However, implementation of this invention is not limited to this, For example, a pier floor slab etc. It can also be applied to reinforcement.
[0046]
【The invention's effect】
As described above in detail in the embodiments, according to the method of reinforcing an existing structure according to the present invention, economic reinforcement can be performed while avoiding diversification of steps and increase in labor.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an external view of a state in which a reinforcement method for an existing structure according to the present invention has been completed.
FIG. 2 is an enlarged view of a portion A in FIG.
FIG. 3 is an explanatory sectional view at the time of construction showing a first embodiment of a reinforcing method according to the present invention.
FIG. 4 is an explanatory sectional view at the time of construction showing a second embodiment of the reinforcing method according to the present invention.
[Explanation of symbols]
10 Pier (existing structure)
12 Reinforcement 14 High toughness cement board 16 Fiber sheet 18 Interval 20 Anchor

Claims (7)

In a reinforcing method of an existing structure, a reinforcing material is disposed on a surface of the existing structure, and the reinforcing material is integrally connected to the existing structure.
A method for reinforcing an existing structure, wherein a high-toughness cement boat having a bending strength of 30 MPa or more, a span of 18 cm and a maximum deflection of 25 mm or more is used as the reinforcing material. The method for reinforcing an existing structure according to claim 1, wherein the high-toughness cement board is preliminarily coated on its back side with a water-absorbing regulator for regulating water absorption. In the high toughness cement board, during the press dewatering in the manufacturing process, by sandwiching an uneven forming member such as a wire mesh, to form an uneven portion having a height of about 1 mm and an interval of about 1 to 2 mm. The method for reinforcing an existing structure according to claim 1 or 2, wherein The high-toughness cement board is formed in a rectangular shape having a predetermined length and a predetermined thickness, and when installing a plurality of the high-toughness cement boards on the outer periphery of the existing structure, a space between the adjacent high-toughness cement boards is provided. The method for reinforcing an existing structure according to any one of claims 1 to 3, wherein the bonding is performed using a carbon fiber or an aramid fiber sheet. The high-toughness cement board is arranged at a predetermined distance from the surface of the existing structure, and by filling a hardening material such as concrete or mortar in the space, and hardening the hardening material, The method for reinforcing an existing structure according to any one of claims 1 to 4, wherein the method is integrated with the existing structure. The high-toughness cement board is supported at one end by an anchor embedded in the existing structure so as to provide the space, and after arranging a reinforcing steel material such as a reinforcing bar or a PC strand in the space, the hardening is performed. The method for reinforcing an existing structure according to any one of claims 1 to 5, wherein a material is filled. The high-toughness cement board is installed adjacent to the surface of the existing structure, and injects a curable resin from the surface side of the high-toughness cement board, and is integrated with the existing structure by curing the curable resin. The method for reinforcing an existing structure according to any one of claims 1 to 4, wherein:

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