JP3080568B2 - Method for reinforcing concrete bridge and fixing device used therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reinforcing a concrete bridge in which a reinforcing member is newly added to a girder of a concrete bridge or a lower surface of a floor slab (hereinafter referred to as a floor slab) to reinforce the bridge.

[0002]

2. Description of the Related Art Concrete bridge decks and the like are subjected to the most severe load and stress among the main members of a road bridge due to the direct and repeated application of the wheel load of an automobile. For this reason, cracks in one direction and vertical and horizontal cracks are generated on the lower surface of the floor slab or the like, and these cracks grow to form a fine mesh, which eventually causes concrete to fall off.

[0003] If such damages are left untreated, the cracks will further develop, leading to corrosion of the reinforcing steel, eventually leading to the destruction of the bridge. Therefore, as a method of avoiding such a situation, an appropriate repair of the lower surface of the concrete bridge floor slab has been performed at the stage when an initial crack occurs.

For example, as a repair method, a resin injection method for injecting an epoxy resin into a crack of a floor slab or the like to integrate it with concrete, a sheet or a sheet for preventing rainwater or the like from entering the floor slab or the like. A waterproofing method for forming a protective layer such as a coating film, and a fiber reinforced resin [FRP (fiber reinforced plate)]
FRP bonding method for bonding slabs), a cross section repair method for filling a bean plate such as a floor slab, cavities, peeling, and the like with a cement mortar or a resin mortar.

[0005] Although these construction methods can be expected to prevent the deterioration of concrete bridge decks and the like and the rust prevention effect of reinforcing steel to some extent, they are limited to repairing existing bridge decks and the like.
The strength of the bridge slab and the like itself has not been increased.

In order to solve such a problem, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 61-146904, a method of applying a surface coating material to the back surface of a washed existing bridge floor slab, and forming a wire mesh thereon. A method of repairing and reinforcing bridge decks and the like in which a surface coating material is applied on the wire netting is disclosed.

[0007] Further, a reinforcing method has been developed in which the above-mentioned method is further developed to improve the fixing property of the wire mesh so that the structure and the wire mesh before reinforcement can be integrally resisted against a load. No. 4238 discloses this.

[0008] The technique described in the publication uses a tapered fixing member whose cross section increases from the base end side to the distal end side in order to fix the mesh reinforcing bar. At the intersection. Thus, while the intersection portion and the tapered portion are in contact with each other, a tensile force in the surface direction is applied to the mesh reinforcing bar, and the existing structure and the mesh reinforcing bar are integrated.

[0009]

In the above method,
It is most important that the taper portion of the fixture accurately contacts the intersection of the mesh reinforcing bars as the fixture is driven in. Therefore, it is necessary to accurately form holes for driving the fixture in the underside of the concrete bridge. is there. Therefore, when forming holes for driving fixtures on the underside of the conventional bridge,
A reinforcing mesh reinforcing bar is temporarily placed at a predetermined position by means of a support or the like, and in this state, holes for driving fasteners are drilled at several locations using a hand drill, and thereafter, the fasteners are driven.

However, since the above-described mesh reinforcing bar is conventionally used as a reinforcing member, when a drill rotating at a high speed makes any contact with the reinforcing bar at the time of forming a hole using a hand drill, the temporary reinforcing bar is used. The placed rebar is flipped and the whole is displaced, making accurate positioning difficult. In particular, since the reinforcing mesh reinforcing bar has a weight of ten kilograms per sheet, it is very difficult to accurately arrange it on the lower surface of the bridge, unlike the one arranged on the upper surface or the side surface of the structure.

Furthermore, the support for supporting the reinforcing bar from below is set up on the scaffold plate. However, the scaffold plate is bent due to the passage of an operator or the like, and the reinforcing bar is displaced due to loosening of the support. In some cases, there is a risk that heavy rebar will fall.

The problem to be solved in the present invention is to provide a method for reinforcing a concrete bridge which can be accurately positioned by a drill and which has high safety, and a fixing tool used therefor. .

[0013]

In order to solve the above-mentioned problems, a method for reinforcing a concrete bridge according to the present invention includes the steps of temporarily disposing a grid-like reinforcing member formed of a fiber-reinforced resin on the lower surface of a concrete bridge, and then fixing the fixture. The lattice-shaped reinforcing member is fixed to the lower surface of the concrete bridge while applying a tensile force in a plane direction to the lattice-shaped reinforcing member, and then a coating layer covering the reinforcing member is formed.

As the fiber reinforced resin, continuous fibers such as glass fiber, carbon fiber, and aramid fiber can be used. As the resin, vinyl ester (Vinyl Ester) having particularly excellent chemical resistance is used. Can be.

As a commercially available product, Nefcom (registered trademark) sold by Nefcom Co., Ltd. can be suitably used. This Nefcom has a spacing of 5 while impregnating a continuous fiber such as carbon fiber, glass fiber, or aramid fiber with resin.
It is integrally molded in a grid shape of 0, 100, 150 mm etc., and has a specific gravity of 1.3 to 1.7, which is 1/4 to 1/6 of steel.
The tensile strength is 4 to 5 times that of steel bars, similar to PC steel wire.
The tensile modulus is 2/3 to 1/4 of that of the steel material, and the area of elastic deformation is 2 to 5 times that of the PC steel wire. Furthermore, since the lattice crossing portion has a so-called laminate structure in which fibers are alternately stacked, it has excellent binding power, and a sufficient strength is secured even when a tension is applied to the crossing portion by the fixture. Further, unlike the case of the reinforcing bar, the intersection portion is on the same plane, so that the covering can be made thin.

Further, as a fixing tool used in the method for reinforcing a concrete bridge, a rod-shaped insertion portion to be inserted and fixed into a hole formed in the concrete bridge, and a connecting portion connected to the insertion portion and the other end side from the insertion portion side A tapered portion having a continuously increasing cross section toward the surface, a dish-shaped head connected to the tapered portion, and a reinforcing bridge for a concrete bridge having a resin layer formed on the outer peripheral surface of the tapered portion Tools can be used.

Here, the resin layer covering the outer peripheral surface of the tapered portion may damage the grid intersection of the reinforcing member formed by the fiber reinforcing member when the fixing tool is driven in contact with the grid intersection of the reinforcing member. And to reduce the friction with the intersection and improve the driving efficiency, especially
It is preferable to use a resin of the same material as the reinforcing member.

[0018]

[Function] The reinforcing member made of fiber reinforced resin is not only easily fixed to the lower surface of a concrete bridge due to its light weight, but also has a surface hardness much lower than that of steel, so that a hand drill temporarily contacts the member. In this case, the surface is only slightly shaved, so that it does not slip out like a steel rebar.

Further, as described above, the fiber reinforced resin has a region of elastic deformation 2 to 5 times as large as that of the PC steel wire, and therefore imparts a considerably higher tensile force in the plane direction than that of a reinforcing bar without plastic deformation. Which allows us to
Further, the integration of the reinforcing member and the existing structure is ensured.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below based on embodiments shown in the drawings.

FIG. 1 is an overall view of a concrete bridge to which the present invention is applied, and 1 is a reinforced concrete slab.
A ground cover 2 is formed at both ends of the floor slab, and three rows of bridge girders 3 are provided on the lower surface of the floor slab 1. The reinforcing coating layer 9 according to this embodiment is formed on the entire lower surface of the floor slab 1.

Next, a method for forming the coating layer 9 will be described with reference to FIGS. As shown in FIG. 2 (a), first, the degraded material on the surface of the concrete floor slab 1 is removed by water sand blasting or the like, and then 200 kgf is further removed.
The entire surface is washed with high-pressure water washing with jet water of not less than / cm ² .

Next, as shown in FIG. 2B, a reinforcing member 5 formed of a fiber-reinforced resin in a 1.8 × 3 to 4 m lattice-like shape is supported from below by a support 20 and the lower surface of the concrete slab 1 is formed. Is temporarily arranged.

FIG. 4 is a perspective view showing the reinforcing member 5. The reinforcing member 5 is made of continuous fiber such as glass fiber, carbon fiber, or aramid fiber, and vinyl ester (Vinyl Ester) which is particularly excellent in chemical resistance is used as a resin. Used. The reinforcing member 5 has a specific gravity of 1.3 to 1.7, a tensile strength of 4 to 5 times that of a reinforcing bar, and a tensile elasticity of 2/3 to that of steel.
The area of the elastic deformation is 1/4, which is 2 to 5 times that of the PC steel strand. Further, as shown in the partially enlarged view, since the fibers are alternately laminated at the lattice intersection, a sufficient strength can be obtained by the binding effect of the fibers in addition to the adhesive strength of the resin.
Furthermore, unlike the case of the reinforcing bar, the intersection portion is on the same plane, so that the covering can be made thin.

Returning to FIG. 2C, a hole 1a for inserting a fixture, which will be described later, is drilled in the lower surface of the concrete floor slab 1 along the lattice intersection of the reinforcing member 5 using a drill. Thus, by drilling the fixture insertion hole 1a in a state where the reinforcing member 5 is actually temporarily arranged, drilling at a more accurate position can be performed as compared with the case where the fixture insertion hole is drilled in advance. It becomes possible.

Next, as shown in FIG. 2 (d), a fixing member 6 is inserted into the fixing member insertion hole 1a, and the reinforcing member 5 is fixed to the lower surface of the concrete floor slab 1 by driving with a vibration hammer.

FIG. 5 shows the fixing device 6, which has a slot 7 a formed at the tip thereof and is inserted into the floor slab 1.
An anchor provided with a tapered portion 7c which is continuously provided to the insertion portion 7b and whose cross section is continuously enlarged from the insertion portion 7b side to the other end side, and a dish-shaped head 7d provided continuously to the tapered portion 7c. Main body 7 and driving pin 8 for fixing inserted into a through hole (not shown) formed in the axial direction of anchor main body 7
Consists of Reference numeral 7e denotes a resin layer made of vinyl ester formed on the outer peripheral surface of the tapered portion 7c. With this, when the fixing tool 6 is driven in contact with the grid intersection of the reinforcing member 5, the reinforcing layer formed by the fiber reinforcing member Member 5
Can be prevented from being damaged, and the friction with the intersection can be reduced to improve the driving efficiency.

The size of the fixture 6 depends on the size of the lattice of the reinforcing member 5, but it is appropriate that the insertion portion 7b is 6 to 8 cm and the tapered portion 7c is 2 to 3 cm.

By driving the fixture 6 into the fixture insertion hole 1a formed in the concrete floor slab 1, the taper portion 7 is formed.
Due to the wedge action c, a tension is applied to the entire reinforcing member 5 in the direction indicated by the arrow in FIG. 6, that is, in the surface direction. Also, due to the presence of the tapered portion 7c, it is possible to securely fix even if the insertion hole 1a of the fixing tool 6 formed beforehand is slightly shifted from a regular position or the intersection of the reinforcing member 5 is slightly shifted. become able to. In the present embodiment, a tension is applied from the center of the span of the floor slab 1, that is, from the portion having the largest deflection to the outside.

Further, from this state, as shown in FIG.
A coating layer 9a (see FIG. 3) for strengthening the lower surface of the concrete bridge and improving the rust prevention effect and the adhesive strength of the existing reinforcing bars.
(A)) an intermediate coating layer 9b (FIG. 3 (b)) formed on the surface of the coating layer 9a so as to cover the reinforcing member 5 and having a rust prevention effect, a salt damage suppressing effect, and the like of the reinforcing member 5; Coating layer 9b
Coating layer 9 formed on the surface of the surface and having a neutralization preventing effect, a salt damage suppressing effect, an alkali aggregate reaction suppressing effect, and a low water permeability effect.
A coating layer 9 made of c (FIG. 3B) is formed. Here, the coating layer 9a is applied by spraying, and the intermediate coating layer 9b and the upper coating layer 9c are applied by ironing.

FIG. 7 is an explanatory view showing the behavior of the reinforcing member 5 and the fixing tool 6 due to the bending of the floor slab 1 after the repair is completed. As shown in FIG. ,
Granted tensioning force F in the arrow direction, the thereby reinforcing member 5, so that the F _x, the prestress F _y respectively introduced. Therefore, as shown by the one-dot chain line, even when the fixing tool 6 moves due to the bending of the floor slab 1, the reinforcing member 5 also moves as shown by the one-dot chain line following this, and the reinforcing member 5 and the fixing tool 6 A gap as in the related art does not occur between them.

As described above, in the present embodiment, by using a reinforcing member made of fiber reinforced resin, which is much lighter than a reinforcing bar, as the reinforcing member 5, not only can it be easily fixed to the lower surface of the concrete bridge, but also it can be used. The surface hardness is much lower than that of steel, so that even if the drill makes contact, the surface is only slightly shaved, so that it will not be displaced by being flipped like a steel rebar.

Further, as described above, the fiber-reinforced resin has a region of elastic deformation that is 2 to 5 times as large as that of the PC steel wire, and thus imparts a considerably higher tensile force in the plane direction than that of a reinforcing bar without plastic deformation. Which allows us to
Further, the integration of the reinforcing member and the existing structure can be made sure.

As a result of conducting the test according to the procedure shown in the present embodiment, the tensile stress of the existing slab reinforcement was 80% after the reinforcement with respect to the load of 20 tons.
% Stress was reduced, and the reinforcing effect of the reinforcing member was confirmed. As described above, according to the reinforcing method of the present embodiment, the floor slab is prevented from cracking and the effect of preventing the progress of the deterioration of the floor slab due to shearing and fatigue fracture is obtained by maintaining the effective cross section of the concrete by not only bending. Can be

The method of this embodiment can be applied not only to repairing a damaged concrete structure but also to a case where a bridge designed at T20 is strengthened at T25. Further, the present invention can be similarly applied not only to the floor slab but also to the reinforcement of the lower surface of the girder. In particular, the present invention is most effective for floor slabs and girders whose bending is constantly repeated by passing traffic even during construction.

[0036]

According to the present invention, the following effects can be obtained.

(A) By using a reinforcing member made of fiber reinforced resin which is much lighter than a reinforcing bar as a reinforcing member, not only is safety excellent and easy to fix to the lower surface of a concrete bridge, but also when handling a hand drill. Is also prevented from being fluctuated, and accurate positioning can be performed.

(B) Since the area of elastic deformation of the fiber reinforced resin is two to five times as large as that of the PC steel strand, the integration of the reinforcing member and the existing structure can be further ensured.

(C) By forming the resin layer on the tapered portion of the fixture, it is possible to reduce damage to the intersection of the reinforcing members when the fixture is driven, and to reduce the contact friction, thereby improving workability. Is improved.

[Brief description of the drawings]

FIG. 1 is an overall view of a bridge to which the present invention is applied.

FIG. 2 is an explanatory view showing a construction procedure of the present invention.

FIG. 3 is an explanatory view showing a construction procedure of the present invention.

FIG. 4 is a perspective view of a reinforcing member.

FIG. 5 is a front view of a fixture.

FIG. 6 is a view taken along the line AA of FIG. 1;

FIG. 7 is a view showing behaviors of a reinforcing member and a fixture due to bending of a floor slab.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Floor slab 2 Ground covering 3 Bridge girder 5 Reinforcement member 6 Fixture 7 Anchor main body 7a Split groove 7b Insertion part 7c Taper part 7d Head 7e Resin layer 8 Driving pin 9 Coating layer 9a Coating layer 9b Middle coating layer 9c Top coating layer

Claims (2)

(57) [Claims] 1. A grid-like reinforcing member formed of a fiber-reinforced resin is temporarily disposed on a lower surface of a concrete bridge, and then the grid-like reinforcing member is attached to the grid-like reinforcing member by applying a tension in a surface direction by a fixing tool. A method for reinforcing a concrete bridge, wherein the method is fixed to a lower surface of the concrete bridge, and thereafter, a coating layer covering the reinforcing member is formed. 2. A fixing tool for use in the method for reinforcing a concrete bridge according to claim 1, wherein the rod-shaped insertion portion is inserted into and fixed to a hole formed in the concrete bridge; A tapered portion whose cross section is continuously enlarged from the portion side to the other end side, and a dish-shaped head connected to the tapered portion, and further a resin layer is formed on an outer peripheral surface of the tapered portion. A fixing fixture for reinforcing a concrete bridge, characterized in that: