JPH0593463A - Reinforcing method for existing concrete structure - Google Patents

Abstract

PURPOSE:To set fixing strength as strength durable to shearing and to provide the original strength of a FRP material for reinforcement of a concrete structure, in a method to perform reinforcement in a way that an FRP reinforcing substance is fixed on the portion surface of an existing concrete structure on which a tensile force is exerted by a bending moment. CONSTITUTION:Nails 4 are driven at intervals of a given distance from a position above a reinforcing fiber sheet 3, adhered to a concrete structure surface, or the reinforcing fibre sheet impregnated with a thermosetting resin composition 5. By curing the resin composition 5, an FRP reinforcing substance 6 fixed to the structure surface by means of the nails 4 and through adhesion is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an existing concrete structure, and more particularly to a method for reinforcing an existing concrete structure such as a floor slab where a tensile force caused by a bending moment acts.

[0002]

A tensile force is applied to the floor slab of the concrete structure, the lower surface of the beam, the upper surface of the cantilever, or the like by a load. For this reason, there are many cases in which these existing structures are bent, cracked, or dented and require repair. However, when trying to reinforce with steel or the like, the self-weight of the structure becomes remarkably large, and it becomes necessary to reinforce the foundation, columns, etc. that support the self-weight, which makes construction very difficult.

In recent years, carbon fiber, aromatic polyamide fiber (aramid fiber), glass fiber or the like is used as a reinforcing material, and thermosetting resin such as epoxy resin or unsaturated polyester resin is used as a base material. ) Has been proposed to reinforce. FRP is lightweight, has high tensile strength and tensile modulus, and has excellent weather resistance.
It has excellent merits used for repair, such as reducing the burden of increased load.

However, the conventional FRP reinforcing means is a structure in which a tensile force acts, and an FRP reinforcing body coated or impregnated with a thermosetting resin composition is fixed by adhesion. When a tensile force acts on the surface of the structure and the bonded fixed layer bends, shear failure easily occurs and peeling occurs, and the original high strength of FRP cannot be expressed in reinforcement. Various means have been proposed to prevent this shear failure, but none have been satisfactory.

The present invention is intended to solve the above problems. The purpose is the existing concrete structure and FRP
Another object of the present invention is to propose a method for reinforcing an existing concrete structure that can prevent shear failure of the fixed layer between the reinforcing body and the original strength of FRP.

[0006]

[Means for Solving the Problems] This method for reinforcing an existing concrete structure is such that a reinforcing fiber sheet is adhered to the surface of the existing concrete structure where the tensile force acts, and then a thermosetting resin composition is applied. Or, a reinforcing method in which a reinforcing fiber sheet impregnated with a thermosetting resin composition is adhered, and the composition is cured to form a fiber-reinforced plastic reinforcing body, which is obtained from above the adhered reinforcing sheet, or It is characterized in that nails are driven into the concrete structure at predetermined intervals from the uncured composition which has been applied or impregnated, and the reinforcing fiber sheet is fixed.

The reinforcing fibers used in the present invention are carbon fibers, aromatic polyamide fibers, glass fibers and the like. Among them, carbon fiber has a high tensile strength and a high tensile elastic modulus, and is more suitable for this purpose. The reinforcing fibers are used by orienting long fibers in one direction to form a unidirectionally arranged sheet, a bidirectionally arranged sheet, a woven sheet or the like. The unidirectionally arranged sheet is suitable because it can be exerted without impairing the tensile strength and elastic modulus of the reinforcing fibers constituting the unidirectionally arranged sheet, and can be effectively utilized by orienting it in the direction in which the tensile force acts.

[0008]

The tensile force acting on the concrete structure is in the direction orthogonal to the axis with respect to the nails, but the nails have high strength in the orthogonal direction. Therefore, the fixing layer that uses both adhesion and nailing can exhibit a large yield strength against the shearing force acting on the interface. Since the nails are driven before the resin composition is cured, after the curing, the reinforcing fiber sheet and the resin composition are integrated,
The force that forms the FRP reinforcing body and acts on the nail is transmitted to the FRP reinforcing body, and the performance of the FRP can be expressed in the reinforcement of the structure.
In addition, since nails are driven at a predetermined interval, the amount of shear deformation that acts on the adhesive layer between nails is small, it is hard to break, and even if the adhesive layer partially undergoes shear failure, the nail interval There is no destruction over the above.

[0009]

EXAMPLE FIG. 1 shows a concrete floor slab 1, in which a load F is applied from the upper surface, and a tensile force T due to a bending moment acts on the lower surface. This embodiment is a repair method for preventing the floor slab 1 from being bent or broken by the tensile force T.

First, an epoxy resin-based primer and then an epoxy resin-based adhesive 2 are applied to the lower surface of the floor slab 1, and a reinforcing fiber sheet 3 in which long carbon fibers are arranged in one direction is applied to the tensile force T direction. Orient it in the direction of ten and bond it so that it does not loosen. From above, nails 4 are driven in at a grid-like position with a predetermined interval to fix the reinforcing fiber sheet 3 to the floor slab 1.

As shown in FIG. 2, the epoxy resin composition 5 is applied from above the reinforcing fiber sheet 3, impregnated and cured at room temperature to form the FRP reinforcing body 6, and the reinforcing work is completed.

In the embodiment shown in FIGS. 3 and 4, wind pressure F is applied,
This is an example in which the side surface of the upright shield wall 7 on which the tensile force T acts due to the bending moment is reinforced.

A primer 2 is applied to the side surface of the shielding wall 6, and a reinforcing fiber sheet 3 in which carbon fibers impregnated with an epoxy resin composition 5 are arranged in one direction is tensioned and adhered.
The holding plates 8 which are long in the lateral direction are arranged on the reinforced sheet 3 at predetermined vertical intervals, and the nails 4 are arranged at predetermined intervals from above.
And the reinforcing fiber sheet 3 is fixed. The resin composition is cured to form the FRP reinforcing body 6.

In the above embodiment, the reinforcement is aimed at the flat portion where the tensile force acts in one direction. However, when the tensile force acts in two directions, the unidirectionally arranged sheets are stacked in two orthogonal directions. Or can be reinforced with a bidirectional array sheet. Further, the reinforcement for a curved surface portion such as a cylindrical shape or a spherical shape can be similarly performed.

[0015]

The present invention is as described above, and enhances the bond strength between the surface of the concrete structure and the FRP reinforcement, prevents the shear failure of the bond layer, and enhances the original strength of the FRP material to reinforce the concrete structure. It has become possible to demonstrate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a reinforcing fiber sheet is attached and fixed to a lower surface of a floor slab.

FIG. 2 is a cross-sectional view showing a state in which a resin composition is applied to a reinforcing fiber sheet.

FIG. 3 is a cross-sectional view of a state in which a reinforcing fiber sheet impregnated with a resin composition is attached and fixed to the side surface of the shielding wall.

FIG. 4 is a plan view of FIG.

[Explanation of symbols]

1 ... Floor slab, 2 ... Epoxy resin adhesive, 3 ... Reinforcing fiber sheet, 4 ... Nail, 5 ... Epoxy resin composition, 6 ... FR
P reinforcement, 7 ... Shielding wall, 8 ... Holding plate.

Claims (1)

[Claims] 1. Reinforcement in which a thermosetting resin composition is applied or impregnated with a thermosetting resin composition after adhering a reinforcing fiber sheet to the surface of the existing concrete structure where the tensile force acts. A reinforcing method for adhering a fiber sheet and curing the composition to form a fiber-reinforced plastic reinforcement, comprising the step of applying an uncured composition on the adhered reinforcing fiber sheet or by applying or impregnating the composition. A method for reinforcing an existing concrete structure, characterized in that nails are driven into the concrete structure from above at a predetermined interval and a reinforcing fiber sheet is fixed.