JPH0447292Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is suitable for fixing the ends of PC tendons made of fiber-reinforced plastics using glass fibers, carbon fibers, and other fibers, that is, FRP. This is an end fixture for FRP PC tendons.

(Prior Art) A conventional end fixing device for PC tendons has a tapered through hole 15 in the center into which a male cone can be inserted, as shown in FIGS. 4 to 6.
A female cone 17 whose narrow end portion of the through hole 15 is supported by a bearing pressure plate 16, and a through hole 1 of the female cone 17.
5 and a multi-split male cone 20 that grips a PC tension material 19 inserted into a cylindrical cavity 18 formed in the center is generally used.

Such an end fixing device for PC tendons is designed to hold the PC tendons 1 introduced through the bearing plate 16 into the through hole 15 of the female cone 17 and the cavity 18 of the male cone 20.
9 is strongly gripped by the male cone 20 by a wedge action.
This is to prevent the PC tension material 19 from coming off. In addition, this PC tension material 19 has excellent tensile strength.
Prestressed steel materials such as prestressed steel wire and steel bars are mainly used.

The male cone 20 of such a conventional PC tendon end fixture is formed so that its tip remains in the through hole 15 of the female cone 17 when the PC tendon 19 is strongly gripped as described above. In addition, the inner circumferential wall 21 forming the cavity 18 of the male cone 20 has an annular groove 22 continuously provided from the vicinity of the tip to the vicinity of the rear end, and the surface is formed in a sharp uneven shape. The cavity 18 was formed to have a cylindrical shape with approximately the same diameter from the tip to the rear end.

(Problem that the invention aims to solve) However, recently, PC tension material made of fiber reinforced plastic, that is, FRP, has been developed.
Now you can use it.

Compared to conventional steel PC tendons, this FRP PC tendon has almost the same tensile strength, has excellent corrosion resistance, and has a high specific elongation. It has advantages such as low stress loss, but on the other hand, it also has the disadvantage that when the surface is scratched, it easily breaks due to the scratches, resulting in an extremely low tensile strength.

When a conventional PC tendon end fixture is used for such FRP PC tendons, the inner peripheral wall of the multi-split male cone of the PC tendon end fixture is formed into a sharp uneven shape. Therefore, when gripping the FRP PC tension material strongly, the gripping surface of the tension material may be damaged,
The opening edges on both ends of the inner peripheral wall of the multi-split male cone and the opening edge on the support plate side of the female cone's through hole are formed at almost right angles, so the FRP PC tension material will not be pressed or rubbed against them. When this happens, stress concentrates on the edges and damages the contact area of the tension material.
There was a problem that the tensile strength of FRP PC tendons was extremely reduced.

In view of such conventional problems, the present invention aims to provide an end fixing device for FRP PC tendons that does not cause an extreme decrease in tensile strength and is suitable for fixing the ends of FRP PC tendons. It is something.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an end fixing device for FRP PC tendons, in which the fixing device is made by dividing a rectangular parallelepiped into approximately two halves in the longitudinal direction. The grip has two grip parts, each of which has a groove with a semicircular cross section formed in the longitudinal direction on the dividing surface of both grip parts. Each of the grips is expanded into a flap shape, and a plurality of through-holes for bolt insertion are drilled perpendicularly to the grooves at opposing positions on both sides of the grooves in the two half-shaped grips. A bolt is inserted into each of the through holes.

(Function) When the concave groove configured as described above grips the FRP PC tendon inserted into the concave groove, the entire concave groove surface grips the FRP PC tendon.
When the tension material is pressed against both end edges of the groove, the entire inclined surface of both ends presses against the FRP PC tension material, so stress is dispersed.

(Example) Next, an example of the implementation of the present invention will be described with reference to the drawings of FIGS. 1 to 3.

1 in the figure is an end fixture for FRP PC tendons according to the present invention.

The FRP PC tension material 1 is a rectangular parallelepiped approximately 2 in the vertical direction.
Two half-shaped grip parts 2, 2 obtained by dividing into equal parts
have.

Both grip parts 2, 2 are arranged with their dividing surfaces 3 facing each other. In the center of this dividing plane 3
A concave groove 5 having a semicircular cross section and forming a cylindrical gap 4 for passing the FRP PC tendon is formed to be fully extended in the longitudinal direction.

As shown in FIG. 2, both concave grooves 5 are each formed to have a smooth surface and are widened at both ends 5a and 5b, so that when both grip portions 2 are brought together, they form a wrap-around shape.

A plurality of through holes for inserting bolts arranged perpendicularly to the groove 5 are bored at opposing positions on both sides of the groove 5. Further, as shown in FIG. 1B, a step portion 2a for positioning is provided.

A bolt 6 is inserted into each of the through holes with the tip thereof protruding from the through hole.

A nut 7 is screwed onto the tip of the bolt 6. 8 is a washer.

In addition, the grip parts 2, 2, the bolt 6, and the nut 7
It is desirable that the fasteners are made of a material with excellent corrosion resistance, such as ceramics.

When using the FRP PC tendon end fixture 1 configured as described above, one longitudinal end of the end fixture 1 is attached to a bearing plate 9 as shown in FIG.
through the bearing plate 9 and into the cylindrical gap 4 formed by the concave groove 5 of both grip parts 3, 3.
After introducing the FRP PC tension material 10, both the grip parts 3, 3 are tightened using the tightening means of the bolt 6 and nut 7, and the surface of the concave groove 5 of the grip part is tightened.
By gripping the PC tendon material 10, the PC tendon material 10 is fixed.

(Effects of the invention) The present invention has an end fixing device for FPR PC tendons configured as described above, and the groove surface of the grip portion that grips the FRP PC tendon is formed to be smooth. To grasp the FRP PC tendon as a whole, and to widen both ends of the groove so that both ends of the cylindrical gap are curved, forming gentle slopes at both ends of the groove. Made of FRP
When the PC tension material is pressed against both edges of the concave groove, the stress is distributed over the entire slope.
Since the surface of the FRP PC tendon is not easily scratched, the end fixing device for the FRP PC tendon according to the present invention is made of FRP without causing an extreme decrease in the tensile strength of the FRP PC tendon. It became suitable for PC tension material. Furthermore, the upper and lower grip portions are positioned by the stepped portion, making assembly easy. moreover,
Since both ends of the cylindrical gap are formed in a rounded shape, workability is improved.

[Brief explanation of the drawing]

Figures 1 and 2 show one embodiment of the present invention, in which Figure 1A is a side view, Figure 1B is a front view, and Figure 1B is a front view.
The figures are a sectional view taken along the - line in Fig.
The figure is a sectional view of a conventional end fixture for PC tendons, Figure 5 is a perspective view showing a three-split male cone of a conventional end fixture for PC tendons, and Figure 6 is the same as Figure 5. Show 3
FIG. 2 is a plan view showing one divided body of a split male cone. 1... End fixture for FRP PC tension material, 2...
Grip portion, 3... Divided surface, 4... Cylindrical gap,
5... groove, 6... bolt, 7... nut.

Claims (1)

[Scope of utility model registration request] The end fixing device for FRP PC tendons has two half-shaped grip portions obtained by dividing a rectangular parallelepiped into approximately two equal parts in the vertical direction, and the dividing surface of both grip portions has a cross section. A semicircular groove is formed in the longitudinal direction, and the groove has a smooth surface and widens at both ends, so that the two half-shaped grip parts A plurality of through-holes for bolt insertion are bored perpendicularly to the groove at opposing positions on both sides of the groove, and a bolt is inserted into each of the through-holes. End fixture for wood.