JPH03224936A - Concrete member - Google Patents

Abstract

PURPOSE:To control the decline of prestress at the minimum by reinforcing a member with a fiber-reinforced plastic wire or rod extended in the direction of axis, and introducing the prestress through the wire or rod. CONSTITUTION:A plurality of FRP members 12 penetrated lengthwise are arranged to a form 18, each of the FRP members 12 is strained, and they are fixed to abutments 20 to maintain their strained conditions. After that, a stirrup 14 is placed to the inside of the form 18, concrete 16 is placed, and after the concrete is solidified, the FRP members 12 are stopped by bond of them with the concrete 16. According to the constitution, stronger prestress can be introduced by making use of the FRP members, the influence of a strain of the concrete 16 is negated, and the decline of the prestress can be controlled at the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a prestressed concrete member.

(Prior Art) Conventionally, concrete members have been proposed for use as column members, beam members, wall plates, floor plates, roof plates, etc., in which prestress is introduced through reinforcing bars made of high-tensile steel.

(Problems to be Solved by the Invention) According to this concrete member, since the reinforcing bars also serve as the prestressing steel material for introducing prestress, compared to prestressed reinforced concrete in which the prestressing steel material is embedded separately from the reinforcing bars, The amount of reinforcing bars required to achieve the same bending resistance can be reduced. In addition, in the prestressed reinforced concrete, the introduced prestress is dispersed between the reinforcing bars and the concrete, and the amount of prestress dispersion to the concrete decreases over time, whereas the reinforcing bars also serve as PC steel materials. Such a phenomenon does not occur in the concrete member.

However, even in this concrete member where the reinforcing bars also serve as prestressing steel, concrete creep, drying shrinkage, and P
Due to the decrease in tension caused by the relaxation of reinforcing bars that also serve as C steel, a decrease in prestress is unavoidable as in the case of prestressed reinforced concrete.

An object of the present invention is to provide a concrete member that can minimize the decline in prestress.

(Means for Solving the Problems) The concrete member according to the present invention is reinforced with fiber-reinforced plastic wires or bars extending in the axial direction, and prestress is introduced through all the wires or bars. There is.

(Functions and Effects) According to the present invention, fiber-reinforced plastic (FRP) wires or rods have extremely high strength and low rigidity compared to high-strength reinforcing bars made of high-tensile steel, so they are large. It withstands tension and causes large tension strain. Therefore, in the concrete member according to the present invention, a large prestress can be introduced in the axial direction compared to the conventional concrete member, and the wire rod Alternatively, the decrease in the tension force of the bar is small, and therefore the prestress decrease is small.

(Example) Referring to FIG. 1, concrete member 1 according to the present invention
0 is shown as a whole with the reference numeral 10 in cross section. The concrete member 10 is formed as a structural member of a building such as a column member, a wall plate, a floor plate, a roof plate, a structural member, etc. in addition to the illustrated beam member.

The concrete member 10 having a rectangular cross section includes a plurality of fiber reinforced plastic (FRP) wires or rods (hereinafter referred to as rFRP materials) 1 located at the four corners of the rectangle.
2 and normal reinforcing bars 14 are embedded in concrete 16 as main bars extending in the longitudinal direction (axial direction of concrete member 10) and stirrups surrounding these main bars, respectively. All F that functions as the main reinforcement
The RP materials 12 are under tension, and prestress is introduced into the concrete 16 via these FRP materials 12. Therefore, the FRP material 12 is the concrete 16
It also serves as a reinforcing member and a member for introducing prestress into the concrete 16.

The prestress is introduced by pretensioning, as shown in FIG. That is, the formwork 18 for forming the beam member has a plurality of Fs passing through it in the longitudinal direction.
The RP material 12 is placed, and then each FRP material is tensioned, its both ends are fixed to abutments 20 arranged on both sides of the formwork 18 to maintain the tension state, and the stirrups are placed inside the formwork 18. After placing the concrete, after the concrete hardens, each FRP material 1
2 by adhering to the concrete 16. The introduction of the prestress and the shaping of the concrete member 10 can be carried out in a factory or at a suitable site on-site.

The maximum allowable tension of FRP material 12 is 60 to 90Kgf/m
m (tensile strength: 130 to 190 Kgf/mm2), and the magnitude of the tension strain at this time is (0.5 to 2.5)
X 10-2. On the other hand, the maximum allowable tension of conventional high-tensile steel bars that serve both as reinforcing members and prestress introduction members for concrete members is 20 to 30 kgf/
mm2 (yield point: 50-70 Kgf/mm2)
, and the magnitude of the tension strain at this time is (1,0~
1.5) X 10-3. Therefore, according to the present invention, in which the FRP material 12 is used as a prestress introduction member that also serves as a reinforcing member for concrete, a larger prestress can be introduced than in the case of using the high-tensile steel rod, and , distortion of concrete caused by drying shrinkage, creep, etc. (0.5 to 1
．． 0) X 10-3 can be canceled out and the decrease in prestress can be minimized.

As an example of the FRP material 12, an epoxy resin matrix and a PAN-based carbon fiber reinforced fiber with a diameter of 6.
An example of this is FRP material of mm.

The tensile strength and elastic modulus of this FRP material are, respectively,
190 Kgf/mm2 and 14,000 Kgf/
mm2 and 0.6X under a tension of 2.5t
A tensile strain of 10-2 is produced. In addition, the adhesive laxation of this FRP material is compared to that of a high-tensile steel bar of the same diameter.
It is about half.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a beam member to which the present invention is applied, and Fig. 2 is a cross-sectional view showing a formwork for forming the beam member and a fiber-reinforced plastic wire or bar placed inside the formwork. It is. 10: Concrete member, 12: Wire or rod made of fiber reinforced plastic. 16: Concrete.

Claims (1)

[Claims] A concrete member reinforced with fiber-reinforced plastic wires or rods extending in the axial direction of the concrete member and prestressed through all the wires or rods.