JPH10311146A - Reinforcing method for concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the execution of work easier and also reduce cost by adhering in parallel a plurality of linear bodies of polyoxymethylene having a particular tensile modulus of elasticity with an adhesive for reinforcement. SOLUTION: A column to be reinforced is chamfered at the corners with a straight line or a circular arc having a very small radius, and the surfaces are smoothened, coated with primer and then hardened. Thereafter, a sheetshaped body of polyoxymethylene linear bodies is adhered in a direction at right angle with the axis of member, and an ending edge portion is superimposed with a starting edge portion and then fixed. The polyoxymethylene linear body has a tensile modulus of elasticity of 20 to 150 GPa, but 30 to 120 GPa is desirable. When processing to a plane-shaped body, polyoxymethylene linear bodies are pulled and arranged in parallel, and nylon fiber or the like is woven as weft yarn in one united body. Polyoxymethylene linear bodies arranged in parallel may be impregnated with a resin. By doing this, the work can be simplified and the time period of the work can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reinforcing a concrete civil engineering or building structure using a polyoxymethylene linear body.

[0002]

2. Description of the Related Art As a conventional reinforcing method using high-strength fiber, there has been a method in which carbon fiber, aramid fiber, or the like is adhered to a concrete column member or a beam member on the surface of the member and reinforced. However, the reinforcing method using carbon fiber is such that when the fiber is firmly attached to a concrete column using an adhesive, the tensile elastic modulus of the fiber is as high as 200 GPa or more. Although a large restraining force is exerted on the concrete, the decrease in proof stress can be suppressed to some extent, but the breaking elongation of the fiber is as small as about 1.5%, so that sufficient deformation performance of the member could not be exhibited. In addition, since the fiber breakage occurs in a destructive manner, if the fiber is damaged, the fiber breaks at a stretch, and the strength of the member is reduced, and the structure is likely to collapse. For the same reason, when a reinforcing member is circulated around a concrete member, the corner portion has a radius of 30.
It was necessary to chamfer with an arc of not less than mm, and the construction took time and effort. In addition, there is a drawback that carbon fibers are very expensive compared to steel sheets used in a reinforcing method based on steel sheet winding which is mainly used as a conventional reinforcing method.

In the reinforcing method using aramid fiber, the tensile modulus of the fiber is about 70 GPa, which is only about one third of that of carbon fiber. It was lower than when reinforced with. Further, aramid fiber has a problem that the cost is almost the same as that of carbon fiber, and it is very expensive as compared with steel plate.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional reinforcing method and effectively reinforces structural members such as columns, beams, walls, floors, and chimneys of concrete structures. In addition, the present invention provides a low-cost method in which the reinforcement is easily applied.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present invention has been accomplished. That is, the present invention provides: 1. A method for reinforcing a concrete structure characterized by attaching a plurality of polyoxymethylene linear bodies having a tensile modulus of 20 to 150 GPa in parallel to the surface of a concrete civil engineering or building structure; The method for reinforcing a concrete structure according to the above 1, wherein a plurality of polyoxymethylene linear bodies are attached in parallel to the surface of a concrete civil engineering / building structure at a gap equal to or less than the maximum size of the coarse aggregate of the concrete to be reinforced, It is.

In the present invention, the reinforcing material to be attached to the surface of concrete is a linear polyoxymethylene having a tensile modulus of 20 to 150 GPa. Although the tensile modulus is about one tenth of that of carbon fiber, a plurality of polyoxymethylene linear bodies having a thickness of 0.5 mm and a width of 1.4 mm are arranged in parallel.
When the layers are arranged, the reinforcing amount (weight ratio) is about 3.7 times the weight of the carbon fiber sheet (200 g / m ² ) which is generally used, the strength of the filament, the size of the outer diameter, and the breakage. The stress concentration can be reduced by the degree of elongation, the restraining effect during plastic deformation of concrete is not completely proportional to the rigidity of the reinforcing material, and the fact that the filament is also strong in the shear direction force It has been confirmed through concrete compression experiments that the concrete exerts a binding force equal to or higher than that of the carbon fiber sheet. In addition, this material can be manufactured at a low cost of 1/6 or less of carbon fiber and aramid fiber, and the reinforcing amount (weight ratio) of about 3.7 times the standard fiber amount of carbon fiber (that is, sheet weight) Even when 730 g / m ² ) is used, the material cost can be lower than that of carbon fiber.

In the concrete compression test, a fiber was attached to the outer periphery of the concrete cylinder at right angles in the direction of the material axis, wrapped around and reinforced, and a compressive force was applied. Both the maximum proof stress and the maximum axial strain were larger when reinforced with a methylene linear body than when reinforced with a carbon fiber sheet. Since the material elongation at break of the polyoxymethylene linear body is much larger than that of carbon fiber, especially in the case of the maximum axial strain, even in experiments, the deformation of concrete is more than three times that of the case where carbon fiber sheet is reinforced. It has been found that the proof strength is maintained and a very large energy absorbing performance is exhibited. In addition, when the polyoxymethylene linear material was broken, the damage gradually increased, leading to breakage, and there was no breaking like a carbon fiber sheet. From these results, it was found that if the reinforcing member is reinforced using a polyoxymethylene linear body having a tensile modulus of 20 to 150 GPa, a sufficient restraining effect can be exerted after bending yield of a concrete member, and a decrease in proof stress can be suppressed. . Further, in this case, since the tensile strength of the polyoxymethylene linear body as the reinforcing material is sufficiently high, it is safe even when an excessive input of seismic force acts.

[0008] The clearance interval of the polyoxymethylene linear body attached to the surface of the concrete structure varies depending on the required reinforcement amount. It is preferable to ensure the following. The polyoxymethylene linear used in the present invention is:
It has a high elongation and is not extremely fragile to shear direction forces like carbon fiber.It has a high resistance, so it has a high reinforcing effect, and since it is a monofilament, it has a large diameter. Less rupture due to concentration. Therefore, mechanically, it is not always necessary to make the composite with a resin, and the construction can be simplified and the construction cost can be reduced.

If a polyoxymethylene linear body having a thickness of about 0.5 mm and a width of about 1.4 mm is used as described above, the rigidity of the linear body is strong when it is attached to a concrete member and reinforced. On the other hand, a high initial rigidity as reinforced by a steel plate can be obtained. In addition, the high elongation performance of the material is also advantageous in terms of construction, and when reinforced by surrounding concrete members, the corners may be chamfered with straight lines or arcs with a minimal radius. Since the smoothing treatment does not require as much precision as when carbon fiber is used, the construction can be simplified and the construction period can be shortened, and the construction cost can be reduced.

[0010] In order to form the state of "parallel plural linear bodies" in the present invention, the linear bodies may be arranged one by one.
It is preferable to use a woven fabric, a knitted fabric, or a net-like planar body. When a plurality of linear bodies are arranged in parallel in this manner, the labor for reinforcing the concrete structure is reduced.

When the sheet is bent, the sheet is attached in the direction of the axis of the column material, and when it is sheared, the sheet is attached in the direction perpendicular to the axis of the member to restrain and reinforce the member. In the case of using a planar body in which methylene linear bodies are arranged, first, the planar bodies are attached in parallel in the axial direction of the pillar, and then the surface of the polyoxymethylene linear body is perpendicular to the axial direction of the material. The body may be pasted and wound. In this case, the polyoxymethylene linear body used in the present invention has a material rupture elongation much larger than that of carbon fiber, and early material rupture due to stress concentration is unlikely to occur. There is no need to insulate with edgings or intentionally use low strength adhesives. When a polyoxymethylene linear body or a tape-like body is used, the pillar can be spirally wound.

The reinforcing method using the polyoxymethylene linear body of the present invention is particularly suitable for reinforcing civil engineering and building structures, particularly bridge piers and piloti columns of buildings. Existing concrete structures and newly constructed concrete structures to which the reinforcing method of the present invention can be applied may be used. It is particularly suitable for existing structures requiring high deformation performance.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in more detail. According to the present invention, a polyoxymethylene linear body or a planar body prepared by arranging and holding a polyoxymethylene linear body in parallel is attached to the surface of a concrete structure using an adhesive such as an epoxy resin. It is to reinforce it.

In the present invention, it is essential to use a polyoxymethylene linear body. In the case of a polyoxymethylene linear body, since it is a monofilament, there is a waist,
High magnification stretching is possible, and the tensile modulus of the linear body can be increased relatively easily. The polyoxymethylene linear body used in the present invention needs to have a tensile modulus of 20 to 150 GPa. The polyoxymethylene linear body can be obtained, for example, by the method disclosed in JP-A-60-183122. This is a method in which a polyoxymethylene unstretched body is molded and then stretched 10 times or more while continuously heating and pressing in a heat medium. The larger the tensile modulus is, the higher the reinforcing effect is. However, in consideration of the relationship with the elastic modulus of concrete and the construction efficiency, it is necessary that the tensile modulus is 20 to 150 GPa.

As disclosed in JP-A-3-17303, in the case of linear polyoxymethylene, the stretching ratio and the tensile modulus and tensile strength have a certain correlation. That is, the tensile modulus of polyoxymethylene of 20 GPa corresponds to a tensile strength of about 1.7 GPa, and the tensile modulus of 40 GPa corresponds to a tensile strength of about 2.3 GPa. Therefore, in the case of a polyoxymethylene linear body, a high tensile modulus is also a high tensile strength. Further, there is a certain correlation between the stretching ratio and the elongation at break. That is, the tensile elastic modulus of polyoxymethylene is 20GP.
a corresponds to a breaking elongation of about 9%, a tensile modulus of 40 GPa corresponds to a breaking elongation of about 5%, and a tensile modulus of 100 GPa corresponds to a breaking elongation of about 3%. If the stretching ratio is too high, the tensile modulus increases, and the initial reinforcing effect is improved. However, the elongation at break is reduced, and the deformation performance upon reinforcement is reduced. Those having a tensile modulus of 20 to 150 GPa are used, preferably 30 to 120 GPa, and particularly preferably those having a tensile modulus of 40 to 100 GPa.

As an example of processing a polyoxymethylene linear body into a planar body, a method of processing a sheet-like body will be described. Other tape-like bodies, woven fabrics, knitted fabrics, and net-like bodies are similarly processed. It can be manufactured at As a method of processing a polyoxymethylene linear body into a planar body such as a sheet-like body,
The polyoxymethylene linear body is constituted as an aggregate in which several to several hundreds are assembled. The shape of the sheet is width 10
１０００1000 m and a thickness of about 1１〜10 mm. In this case, as a method of forming a sheet-like body, there is a method in which polyoxymethylene linear bodies are aligned in parallel, and then knitted with a weft of nylon, ester, glass fiber, or the like to integrate them. In addition, there is a method of impregnating a resin into a polyoxymethylene linear body aligned in parallel. As an example of a preferred embodiment, for example, the wire diameter is 0.5
There is a method of forming a sheet by assembling 5 to 400 pieces having a diameter of 5 mm, more preferably 20 to 400 pieces having a wire diameter of 0.5 to 1.5 mm.

The sheet may be one in which a polyoxymethylene linear body is arranged in one direction, or one in which a two-way polyoxymethylene linear body whose direction is changed by 90 degrees may be arranged. The gap between the parallel polyoxymethylene linear bodies is preferably not more than the maximum dimension of the coarse aggregate of concrete, in order to ensure the reinforcing effect, and the linear bodies are in close contact with each other. It is also possible to increase the amount of reinforcement (of one layer).

Next, a case of reinforcing a concrete prism of a building will be described with respect to the construction of reinforcement. After cleaning, the pillars to be reinforced are chamfered at the corners with a straight line or an arc having a very small radius after cleaning, and the unevenness of the bean plate or the like is smoothed by applying putty or polishing. Then a primer is applied and cured on the surface to improve the affinity with the adhesive. Then, a sheet of polyoxymethylene linear body, which is coated with an adhesive and woven with an ester thread etc., is attached using an epoxy resin adhesive in the direction perpendicular to the material axis, and the end of the sheet is started. Set it over the part. Then, an adhesive is applied over the surface to further enhance the adhesive strength and at the same time protect the surface of the polyoxymethylene linear body.

For a member such as a pillar or a chimney of a concrete structure having no wall and which can be covered around the cross section, a strong adhesive such as an epoxy resin is applied to the polyoxymethylene linear body or the member surface is coated. It can also be applied and wound directly into a spiral. In this case, the end of the polyoxymethylene linear body has a quick-drying adhesive or a jig for temporarily fixing the polyoxymethylene linear body to the concrete surface. It's better to keep it fixed until you show it.

After the polyoxymethylene linear body is adhered to the concrete surface, it is preferable to improve the durability and fire resistance by applying mortar or coating a nonflammable material as a finish. The example which uses the planar body by this invention for shear reinforcement of a concrete column is shown. FIG. 1 shows a sheet-like body 2 in which polyoxymethylene linear bodies 3 are arranged side by side and arranged at almost zero intervals, on a surface of a concrete column 1 in which corners are straight-chamfered, in a direction perpendicular to the material axis. Here is an example of shear reinforcement. FIG. 2 shows that the polyoxymethylene linear bodies 3 are arranged in parallel with warp as warps,
It is a top view of the sheet-like body woven using the ester yarn 4 for the weft.

[0021]

EXAMPLES 1-4 AND COMPARATIVE EXAMPLES 1-3 For a cylinder having a diameter of 10 cm and a height of 20 cm made of concrete having a maximum size of coarse aggregate of 10 mm, a thickness of 0 in the circumferential direction is applied to the entire side surface of the cylinder. A polyoxymethylene linear body having a width of 0.5 mm and a width of 1.4 mm is attached with an epoxy resin adhesive to restrain the member,
The effect of reinforcing the compressive strength of concrete was evaluated by applying axial compressive force. The compressive property of concrete is one indicator of the effect of shear reinforcement. As the evaluation contents, the maximum proof stress, the maximum deformation amount, and the energy absorption amount were measured. For comparison, the same evaluation was performed for carbon fibers and aramid fibers. Table 1 shows the results. From Table 1, it can be seen that the one using the polyoxymethylene linear body has a high reinforcing effect. In Examples 1 to 3, both the maximum proof stress and the amount of axial deformation were higher than Comparative Examples 2 and 3 using carbon fibers and aramid fibers, and the effects of energy absorption were remarkably high.

The basis weight in Tables 1 and 2 is 1 m ²
It indicates the weight of the reinforcing material per unit, and the smaller the basis weight, the smaller the reinforcing amount. In Table 1, Examples 1 to
In Comparative Example 4 and Comparative Example 1, the weight per unit area was larger than that in Comparative Example 2 and Comparative Example 3. However, even in this case, as described above, the polyoxymethylene fiber was one sixth of carbon fiber or aramid fiber.
Since the following material costs are sufficient, a reinforcing material can be manufactured at a lower cost than carbon fiber (Comparative Example 2) and aramid fiber (Comparative Example 3).

[0023]

Examples 5 to 6 and Comparative Example 4 The same evaluation as in Examples 1 to 4 was carried out by changing the distance between the polyoxymethylene linear bodies. As a comparison, the same evaluation was performed for an unreinforced material. From Table 2, it can be seen that the reinforcing effect is higher when the linear body according to the present invention is provided with a clearance interval equal to or less than the maximum dimension of the coarse aggregate of concrete.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

According to the present invention, the polyoxymethylene linear body of the present invention is attached to a concrete structure, thereby improving the strength and toughness of the structure and increasing the amount of energy absorption. Can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example of a concrete column reinforced according to the present invention.

FIG. 2 is a plan view of an example of a sheet used in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete pillar 2 Sheet-like body 3 Polyoxymethylene linear body 4 Ester thread

Claims (2)

[Claims] 1. A method for reinforcing a concrete structure, comprising: attaching a plurality of polyoxymethylene linear bodies having a tensile modulus of elasticity of 20 to 150 GPa in parallel to the surface of a concrete civil engineering or building structure. 2. The method according to claim 1, wherein a plurality of the polyoxymethylene linear bodies are affixed in parallel to the surface of a concrete civil engineering / building structure at an interval equal to or less than the maximum dimension of the coarse aggregate of the concrete to be reinforced. Method for reinforcing concrete structures.