JPS6138043A - Anchor structure of end part of pc steel twisted wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a method for introducing prestress by post-tension into a concrete product by pulling the other end of a PC steel strand whose end is buried in concrete. The present invention relates to a structure for fixing the end of a PC steel strand to be buried in the concrete.

(Prior art) For example, while applying lubricating oil such as grease to the surrounding area,
When introducing prestress into a concrete product using a so-called unbonded PC steel stranded wire whose application surface is covered with a synthetic resin tube, conventionally, the tube on the end side of the wire is peeled from the PC steel, and the peeling Either remove the lubricating oil from the acid part and fix the PC steel stranded wire itself to the concrete, or remove the lubricating oil and fix the fixing plate to the PC steel stranded wire, and fix the fixing plate. The structure of the fixing part is as follows.

(Problem to be Solved by the Invention) However, with the former fixing means, since there is only a small fixing surface between the PC steel strand and the concrete product, the stress of large displacement due to post tension is applied between the fixing surfaces. Therefore, it is difficult to introduce a strong prestress, and there is a risk that the prestress will be released over time.

On the other hand, according to the latter fixing means, although it is easy to provide a large bearing surface that resists post-tension, it has the disadvantage that the concrete is divided at the acidic part, and is expensive, and also It had the disadvantage that it was difficult to fix.

The present invention aims to solve the above-mentioned drawbacks by a simple improvement of the fixing section structure.

(Means for Solving the Problems) In order to achieve the above object, the structure of the end fixing part of the PC steel stranded wire according to the present invention untwists the strand on the end side of the PC steel stranded wire and expands it into a conical shape. The present invention is characterized in that the strands are opened, and conical spiral reinforcements are arranged around the outside of the strands, and the spiral reinforcements and the expanded strands are buried in concrete.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 shows an end fixing part A of a PC steel stranded wire 1.

To explain an example of the manufacturing procedure of this end fixing part A, as shown in FIG. A so-called unbonded PC steel stranded wire B coated with is prepared, the resin tube t on the end side of this is peeled off, and the lubricating oil on the peeled part is wiped off to form a PC steel stranded wire 1.
expose.

Next, as shown in FIG. 3, a spiral strip 2 formed in a conical shape is inserted from the exposed PC steel from the top side of the spiral strip 2! 1, and its top front portion 2a is wrapped around and fixed to the end of the resin tube b.

Next, as shown in FIG. 4, untwist the strand a of the wire 1 from the exposed PC steel; It will be expanded to.

The unbonded PC steel strand B, whose end has been processed in this way, is placed, for example, in the slab molding part C, as shown in FIG. 5, and the expanded strand a...
Concrete) D is poured into the slab molded portion C, burying the spiral reinforcements 2 arranged around the outer circumference of the expanded strands a.

When the concrete (A) D hardens, the end fixing portion A shown in FIG.
is formed, and by pulling the other end of the line B away from the unbonded PCi with the fixing part A as the reaction force point, prestress due to post tension can be introduced into the slab version E. It can be done.

According to the structure of the end fixing part A having the above configuration, since the strand a of the wire 1 is separated from the PC steel, the fixing surface with the concrete D increases, and the strand a... resists post tension. The pull-out strength of is increased.

Furthermore, as shown in FIG. 6, a conical structure F is formed in the vicinity of the anchoring part, and is made up of a conical strand a... and concrete D surrounded by the conical strand a. Since a cone-shaped structure G is formed around the cone-shaped spiral reinforcement 2 and the concrete D restrained by it, a large pulling force due to post tension is applied to the cone-shaped structure F. Even if the cone-shaped structure F acts like a wedge, it will be firmly held by the cone-shaped structure G due to the development of wedge action, and in addition to the increase in the fixing surface due to the expansion of the strands a. The resistance becomes strong.

Furthermore, as explained based on Fig. 3, spiral muscle 2
The wire 1 is stranded with PC steel, and its top front portion 2a is fixed to the end of the resin tube b.As shown in Fig. 7, the spiral wire 2 is placed over the resin tube b side. At the same time, connect the end of the resin tube b to the wire C as necessary.
The winding is fixed, and in this state, the strand a is untwisted and expanded into a conical shape, and then the spiral thread 2 is
Alternatively, instead of covering the spiral thread 2 in advance, it may be placed on the other end of the unbonded PCI line B and placed at a predetermined location. Also good.

Other embodiments are shown from FIG. 8 onwards. The one shown in Fig. 8 is a strand a.
The strands F'a... are tied together with a wire d to maintain the conically expanded state of the strands F'a.

The one shown in FIG. 9 is characterized in that the expanded strands a. are bound to the spiral threads 2 with wires d.

The structure shown in Fig. 10 is characterized in that the expanding strands a... and the spiral reinforcements 2 are buried in advance in a conical concrete mass H, and this is configured to be embedded and fixed in cast-in-place concrete such as a floor. There is. In this case, since the conical concrete mass H is formed in advance, it is possible to bring the prestress introduction earlier, and high-strength concrete can be used only for the anchoring part.

In addition, in the embodiment, the present invention was explained with reference to the unbonded PC steel stranded wire B, but a metal or resin sheath tube is arranged, and the PC steel stranded wire 1 coated with lubricating oil is inserted into this. In this case, the anchoring portion A is formed at the end of the PC steel strand 1 prior to insertion.

Furthermore, it is preferable to arrange the spiral muscle 2 in a completely free state around the outside of the expanded strand a, or it is also possible to fix the spiral muscle 2 to other reinforcements.

(Effects of the Invention) As explained above, according to the structure of the end fixing part of the PC steel stranded wire according to the present invention, since the strands at the end of the PC steel stranded wire are loosened, the fixing surface for concrete products is increased. However, the pull-out strength of the strand against post tension is increased.

In addition, the above-mentioned separated strands are expanded into a conical shape, conical spiral stripes are placed around the outside of the strands, and these are buried in concrete to form a conical strip that is restrained by the spiral strips on the face. It forms a concrete mass, and this concrete mass becomes a large anchoring surface material, and even if an excessive pulling force is applied to the concrete mass, the concrete mass and the cone-shaped concrete product around it This concrete mass is firmly held by the cone-shaped concrete product due to the wedge action between the cone-shaped concrete products.Furthermore, there is no concrete separation like with conventional fixing plates, and it is easy to fix in thin plate parts. In other words, there are no restrictions on the fixing target, and overall, although it is a simple improvement, it has been possible to achieve a fixing effect that is greater than that achieved by the fixing plate.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of the end fixing section, FIGS. 2 to 4 are explanatory diagrams showing an example of the procedure for manufacturing the end fixing section, and FIG. 5 is slab molding. Figure 6 is a functional explanatory diagram of the fixing part,
FIGS. 7 to 10 are explanatory diagrams of another embodiment. 1...PC steel stranded wire, 2...Spiral wire, 3...
- Expansion ring, a... strand. Figure 1

Claims (1)

[Claims] This is a structure for fixing the end of a PC steel stranded wire for introducing prestress by post-tensioning, wherein the end strand of the PC steel stranded wire is untwisted and expanded into a conical shape, and the outside of the strand is untwisted and expanded into a conical shape. A PC characterized in that a conical spiral reinforcement is arranged around the PC, and the spiral reinforcement and the expansion strand are embedded in concrete.
Steel stranded wire end anchorage structure.