JPH03216304A - Manufacture of pc pile having super-high flexural toughness - Google Patents

Abstract

PURPOSE:To produce high-performance PC piles at a low cost with a high workability by using connecting members for longitudinal bars and a cross binding bar, which serve also as spacers, when the cross binding bar is spaced via a gap from and positioned on the outside of a group of the longitudinal bars, and automatically performing the accurate positioning of the cross binding bar within a shuttering by tension of the longitudinal bars. CONSTITUTION:Longitudinal bars 10, 10... are extruded in parallel and cylindrically from dies 14a of a reinforcing steel assemble machine, and a cross binding bar is wound around the longitudinal bars in the form of a spirally cylindrical shape. Portions between the longitudinal bars 10, 10... and the cross binding bar 11 are fixed with connecting members 12, 12... are longitudinal and cross binding bars to form a steel cage 13 for PC piles, whose centerline direction is restricted by the longitudinal bars 10, 10... and whose circumferential direction by the cross binding bar 11. This steel cage is inserted into a shuttering 20 for centrifugal forming, and a tensile force for prestress is applied to the longitudinal bars 10, 10... by straining them. Then, the cross binding bar 11 is positioned at the circumferential parts via the connecting members 12 for longitudinal and cross binding bars. Thereafter, tension is released, and concrete 26 is filled into the shuttering 20 to be formed into a cylindrical shape by a centrifugal forming machine and, after being subjected to necessary curing treatment, the resultant concrete pile is released from the shuttering.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides ultra-high bending toughness P for use in civil engineering and building foundations.
Concerning the manufacturing method of C piles. (Prior art) Conventionally, the production of prestressed concrete piles, in which prestressed concrete piles are made by burying prestressed concrete steel in the binding direction and prestressing the entire width in the width direction, uses a cylindrical formwork and uses centrifugal force to・The centrifugal molding method, which molds into an empty cylindrical shape, is common. In this conventional method, first, a knitting muscle group consisting of PC steel wires 1, 1, etc. is arranged in a cylindrical shape to apply longitudinal prestress using a knitting machine, and hoop muscles 2 are attached to this group. It is knitted into a circular shape by winding it spirally or into multiple rings and welding it (Figure 9A). After removing the upper half of the cylindrical formwork 3 which has been cut in half, insert it into the lower half, and insert each P3 CIl wire 1, 1... into the end iron plate (commonly known as "Hakama").
) 4 and fix it to the tension bearing fitting 5 (Fig. 9B).
After filling a predetermined amount of concrete 6 in this state, the upper half of the cylindrical formwork 3 is covered and fixed, and one tension-bearing metal fitting 5
is pulled by a jack to apply a predetermined tension force to the PC steel wire, and the reaction force is supported by both ends of the cylindrical form 3 (Fig. 9C). In addition, before filling the concrete 6, the cylindrical formwork 3
The upper half of the PC wire is covered and fixed, and the tension support fitting 5 is pulled with a jack to apply a predetermined tension to the PC steel wire, and then concrete is filled with a pump. In this state, the cylindrical form 3 is placed on the rotating roller 7 of the centrifugal molding machine, rotated,
The concrete 6 is formed into a cylindrical shape along the inner surface of the form by centrifugal force (Fig. 9D), and then placed in a curing chamber whose temperature is controlled by steam etc. After curing, the tension bearing fittings 5 are removed. By releasing the tension, prestress is introduced into the concrete. In conventional PC piles manufactured in this way, the bending fracture strength can be increased by increasing the prestress introduced.Increasing the seismic resistance during earthquakes requires plastic deformation at the same time as increasing the bending fracture strength. It is important to increase the capacity, and there was a problem that increasing the breath stress would reduce the plastic deformation capacity, which would actually reduce the seismic performance.

In view of these problems, the inventors of the present invention buried spiral horizontal restraining reinforcement between the cylindrical longitudinal reinforcement group and the outer peripheral surface of the pile in order to improve the performance of the pile. By using burlap fibers, we have developed ultra-high bending toughness PC piles with high bending fracture resistance and high plastic deformation capacity. (Problems to be Solved by the Invention) In order to maintain properties such as the yield strength and high machine elongation rate of the longitudinal reinforcement group, the ultra-high bending toughness PC pile as described above requires spot welding, which is used in the manufacture of cage reinforcements. The organization is unfavorable, and
In order to enhance the bending toughness improvement effect of the transverse restraint reinforcement, it is necessary to arrange the transverse restraint reinforcement as close to the pile outer circumferential surface as possible while keeping it away from the longitudinal reinforcement group. ,
It was necessary to position it strongly to withstand centrifugal molding. However, until now, a manufacturing method suitable for manufacturing such ultra-high bending toughness PC piles had not yet been developed. Therefore, the present inventor developed a P
By arranging the C steel wire group outside and parallel to the longitudinal reinforcement group in a cylindrical shape, and keeping the retractor group under tension during concrete molding, the lateral restraining reinforcement is positioned at a predetermined position. A method was developed to
No. 006). However, this method involves tensioning and burying the vertical PCS wires in addition to the vertical reinforcement groups that mainly apply prestress in the vertical direction, resulting in high costs and requiring a lot of labor for reinforcing. There was a problem. In view of these circumstances, the present invention aims to provide a method for manufacturing the above-mentioned ultra-high bending toughness PC piles economically with less labor. (Means for Achieving the Object) The feature of the method for manufacturing an ultra-high bending toughness PC pile according to the present invention to achieve the above-mentioned objects is that it consists of a PC wire that applies prestress in the longitudinal direction of the pile. A spiral type consisting of a group of longitudinal reinforcements in which a large number of reinforcements are arranged in a circle parallel to each other, and PCS wires buried in the circumferential direction near the outer peripheral surface of the pile placed outside the group of longitudinal reinforcements. A cylindrical PC steel wire cage composed of horizontal restraining bars and a longitudinal and transverse bar connecting tool that also serves as a spacing, fixing each of the vertical bars and horizontal restraining bars at regular intervals is placed in a cylindrical form frame for centrifugal forming. The method is to fix the ends of each of the longitudinal bars to the ends of the cylindrical form and apply tension to position the longitudinal bars and the horizontal restraining bars at predetermined positions, and to perform centrifugal molding in this state. (Function) In this method for manufacturing ultra-high bending toughness PC piles, when the longitudinal reinforcement group is tensed using a jack, the transverse restraint reinforcement supported on the outside via the longitudinal reinforcement connection device separates from the longitudinal reinforcement reinforcement. It will be positioned at that location. In this way, the contraction reinforcements and lateral restraint reinforcements are positioned, and by centrifugal forming with the concrete filled in the formwork, the concrete moves to a uniform thickness on the inner surface of the formwork, and each reinforcement is buried. It is formed into a cylindrical shape.

(Example) Next, an example of implementing the present invention will be explained with reference to FIGS. 1 to 8. Figures 1 and 2 show an example of a PC pile manufactured by the method of the present invention. This PC pile has a cylindrical shape, and has a vertical reinforcement group 10A in which vertical reinforcements 10, 10, . is buried, and on the outside of the PC pile, lateral restraining bars 11 are buried in a spiral arrangement near the outer peripheral surface of the PC pile, oriented in the circumferential direction. These horizontal restraining muscles 11 and vertical muscles 10
-, 10, . . ., there are interposed vertical and horizontal reinforcement connectors 12, 12, . Next, the manufacturing method will be explained. First, the strands 10,
10..., tank restraint bars 11 and longitudinal and transverse bar connectors 12
．． A PCG wire basket 13 consisting of 12... is formed. This PCM wire cage 13 can be formed by using a conventionally used reinforcing bar pyrolysis machine by modifying it. That is, as shown in FIG.
0.10... are made parallel to each other and extruded sequentially in the longitudinal direction into a cylindrical arrangement, and the lateral restraint bars 11 are formed into a spiral strip shape with the required diameter on the outside and sent out sequentially. In this way, the ficus 1 is sent out while maintaining a certain relationship.
0, 10... and the horizontal restraining bars 11 are fixed with vertical and horizontal connectors 12.12..., and in the center line direction by vertical bars 10, 10... Further, the circumferential direction is a PC steel wire cage 13 restricted by lateral restraining bars 11. Note that each of the vertical bars 10, 10, . . . is cut in advance to a required length, and male threads 10a are formed at both ends.

Further, as shown in FIG. 4, for example, the width transverse reinforcement connector 12 is formed by forming a vertical reinforcement fitting part 16 on the -f4A side end face of the support part 15 made of a metal pipe, and having a horizontal restraining reinforcement fitting part 16 on the other end side end face. The joint portions 17 may be formed at predetermined angles, or a metal plate may be press-molded as shown in FIG. 5 to form support portions 15a,
The 111 muscle fitting portion 16a and the lateral restraint muscle fitting portion 17a may be integrally molded. In addition, as shown in FIG.
By arranging the open portions of the respective fitting portions 16b and 17b at both ends of the PC steel wire cage 5b in the same direction, the vertical and horizontal connectors 12 can be assembled by a unidirectional movement from the outer circumferential side of the PC steel wire cage 13 toward the center. The thus assembled PC steel wire basket 13 is inserted into the centrifugal molding form 20, and the end iron plates 21 are assembled inside the form 20 at both ends as shown in FIGS. 7 and 8. ．． After that, both ends of each vertical bar 10, 10, . Fit. Then, one tension-bearing metal fitting 22 is supported at the end of the formwork 20, and the other tension-bearing metal fitting 22 is movably inserted into the formwork 20, and a tension rod 24 is connected to the center thereof. Then, the fixing plate 25 is screwed into the male screw 24a formed outside the rod 24, and the fixing plate 25 is supported by the end of the formwork 20.

After completing the reinforcement arrangement in this way, a jack (not shown) is set at the end of the formwork 20, and one of the tension bearing fittings 22 is pulled through the rod 24 to tension the knitting reinforcement 10. . As a result, a tensile force for prestressing is applied to the spelling muscle 10, and the transverse restraining muscle 11 is
is positioned at a predetermined circumferential position. After tensioning in this manner, the fixing plate 25 is rotated and moved until its surrounding surface comes into contact with the end surface of the formwork 20, and then the tension by the jack is released and the end of the formwork 20 is Remove the jack using force.

Next, the necessary amount of concrete 26 is poured into the formwork 20 by a conventional method.
Filled with water, molded into a cylindrical shape using a centrifugal molding machine, and removed from the mold after the necessary curing treatment. (Effects of the Invention) As described above, in the method for manufacturing an ultra-high bending toughness PC pile of the present invention, when positioning the transverse restraint reinforcements with a gap on the outside of the longitudinal reinforcement group, a tightening transverse reinforcement connector that also serves as a spacer is used. By using it, the accurate positioning of the horizontal restraining bars within the formwork is automatically achieved by the tension of the vertical bars.
This makes it possible to manufacture high-performance PC piles at low cost and with good workability.

[Brief explanation of drawings]

Fig. 1 is a knitting cross-sectional view of an example of a PC pile manufactured according to the present invention, Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1, and Fig. 3 is an assembly of a PC steel wire cage used in the present invention. Example side view, Figure 4~
Fig. 5 is a perspective view showing different examples of vertical and horizontal bar connectors, Fig. 6 is a side view showing another example of the same, and Fig. 7 is a cross-sectional view showing a state in which a PC reinforcing bar cage is assembled into a formwork. , Figure 8 is B in Figure 7.
-B sectional view and FIGS. 9(A) to 9(D) are manufacturing process diagrams showing typical examples of conventional manufacturing methods. 10...PC steel material, 10a...male thread, 11...lateral restraint, 12...transverse bar connector, 13...PC Steel wire basket, 14...
・Reinforcing bar knitting machine, 14a...Dice, 1 5.1 5a, 1 5b・---- Support section, 16
．． 16a, 16b...... Rebar threaded part, 17.17
a. 17b... Lateral restraint muscle threaded part, 20...
...Formwork, 22...Tension bearing fittings, 23...
... Fixing nut, 24 ... Rod, 25 ... Fixing plate, 26 ... Concrete.

Claims (3)

[Claims] (1) A group of vertical reinforcements made of a large number of vertical reinforcements made of PC steel wire that apply prestress in the longitudinal direction of the pile and arranged in a circular pattern parallel to each other, and the outer periphery of the pile arranged outside of the group of vertical reinforcements. It has a spiral horizontal restraining reinforcement made of PC steel wire buried near the surface in the circumferential direction, and a vertical and horizontal reinforcement connecting device that also serves as a spacer and fixing each of the vertical reinforcement and horizontal restraining reinforcement at a fixed interval. The constructed cylindrical PC steel wire basket is housed in a cylindrical form for centrifugal forming, and both ends of each vertical bar are fixed to the ends of the cylindrical frame and tensioned to form a group of longitudinal bars and lateral restraint. A method for manufacturing an ultra-high bending toughness PC pile, characterized by positioning the reinforcement at a predetermined position and performing centrifugal forming in this state. (2) Manufacturing the ultra-high bending toughness PC pile according to claim 1, wherein the PC steel wire cage is assembled in advance, inserted into a cylindrical form for centrifugal forming, and each longitudinal reinforcement is fixed and tensioned. Method. (3) The method for manufacturing an ultra-high bending toughness PC pile according to claim 1, wherein the PC steel wire cage is assembled in a cylindrical form for centrifugal forming, and each vertical reinforcement is fixed and tensioned.