JPS5841231Y2 - concrete pile - Google Patents

Description

[Detailed explanation of the idea] The JIS standards for PC concrete piles are (1) PC
The steel wire is fixed to the fitting.

(2) The bending strength of the joint must be equal to or higher than that of the main body, and (3) Reinforcement must be arranged evenly along the circumference of concentric circles.

There are many types of PC concrete piles that meet these requirements, but the commonly made ones have a structure in which the disc part of the joint fitting is made of thick steel plate and the cylindrical part is made of thin steel plate. It is called the so-called disk type, and is made by welding and connecting the PC concrete to each other with disk metal fittings.

In the disc type joint fitting, the tip part 7 required for connection welding between PC concrete piles has a depth of 4 mm based on design calculations.
, the width is 8 mm (see Figure 1), but in reality it is 9 to 13 m wide.
This is because a circular plate made of steel plate with a thickness of about 1.5 ft. is used.

As shown in Figure 1, this involves the suspension of PC steel wires and the
This was to ensure that there was enough thread to insert and fix the tightening bolts to apply tension to the steel wire.

In order to manufacture disc metal fittings with a thick steel plate structure, a large number of processes are required, including bending of flat steel → welding → lathe finishing → drilling machine processing, and each process takes a long time and requires a lot of manpower and tactics. It was a lot of work.

As mentioned above, if the welded connection between PC concrete piles has a tip part 7 with a depth of 4 mm and a width of g mm, the strength of the connection will be increased regardless of whether it is a disc type joint fitting or a cylindrical type joint fitting. There is no strength or weakness.

In order to make disc metal fittings into thin steel plates, this invention relates to a method (cylindrical type) that connects with the cylindrical part 2, and a PC concrete pile equipped with the joint metal fittings.

(See Figure 6) In other words, if the circular metal fitting can be made into a thin steel plate, the aforementioned manufacturing process can be performed instantaneously in one step using a press machine, which will help reduce costs, and the total weight of the joint metal fitting can also be reduced, reducing material costs. Combined with this, the economic effects can be expected to be extremely large.

It is structurally impossible to directly suspend the PC steel wire 8 on the disc metal fitting 1 made of thin steel plate structure, or to directly pull the PC steel wire. For example, as shown in FIG. This would be possible if the part was expanded into a cylindrical shape and a threaded part was provided for inserting the tightening bolt, but this is still not possible due to the material of the PC steel wire 8.

Therefore, as a suspension means for PQ steel wire, a flat head 9 shape as shown in FIG. 3 is generally used at present.

However, since the flat head method uses low-temperature heating for heading, the cross-sectional area of section a increases and there is no decrease in pile tension as a whole, but there is no increase in the cross-sectional area of section b.

Since it is being heated, it naturally includes a decrease in pile tension per unit area, which was not reasonable from a metal structure standpoint.

(When a breaking load is applied, it always breaks at part b.) Based on the above, the present invention involves threading the tip of the PC steel wire 8, attaching the suspension fittings shown in FIGS. 4 and 5, and This is what was done by realizing the PC steel wire shape shown in the figure.

In order for the suspension fitting to be a so-called suspension fitting rather than a suspension device, (1) the PC steel wire must be able to be fixed and suspended;

(2) Able to install tightening bolts. (3) The internal stress caused by applying tension must be completely absorbed within the suspension fitting itself.

It is necessary that the following three requirements are met independently, and only when these requirements are met will it be possible to use thin steel plates for disc metal fittings.

If even one of the above requirements is missing, the joint fittings will have to be made of thick steel, it will be necessary to add a reinforcing structure, or it will be necessary to apply a predetermined tension to the PC steel wire. That would be impossible.

As shown in FIGS. 4 and 5, the suspension fitting 3 used in the present invention has a flange 6 on the top for attaching the suspension fitting 3 to a joint fitting, and a screw hole 5 for inserting a tightening bolt. A screw hole 4 into which a PC steel wire 8 is screwed is provided at the bottom.

Then, a suspended metal fitting 3 is attached to the tip of the PC steel wire 8 that is organized in a cage shape, and is combined with a joint fitting by a flange 6 to fix the PC steel wire as specified in the JIS standard. It is.

Example 1 PC steel wire 8 knitted into a cage shape as shown in FIG.
On the other hand, attach the suspension fittings 3 one by one, and use the receiver of the disk part of the joint fitting as a stand, and attach the suspension fittings to the unattached PC steel wire 8 from the top surface of the disk fitting. Then, the disc metal fitting 1 is gripped by the flange 6 from the front and back, and the PC steel wire 8 can be fixed to the joint metal fitting.

Embodiment 2 When spot welding the flange 6 of the suspension fitting 3 to a disc metal fitting having a thin steel plate structure, the welding technique is very difficult because the plate thicknesses to be welded are greatly different.

However, since the flange 6 is made of a thin steel plate, the disc metal fitting 1
Spot welding can be easily performed electrically.

(See Figure 6) Only by using a suspension fitting with integrity can the disc part of the joint fitting be made into a thin steel plate, and as a result,
Cylindrical fittings for welding PC concrete piles to each other are 6~
Although a thick steel plate of about 9 mm will be used, the cylindrical fitting 1 can be easily bent using a bender, etc., as in the conventional method, and since the circular plate fitting is made from a thin steel plate, the fitting as a whole can be easily bent. Weight is reduced.

In addition, the workability of the joint fittings has been dramatically improved, and structurally, the cylindrical fitting 2 constitutes a composite concrete pile form containing the PC steel wire, and protects and reinforces the part where the PC steel wire is suspended. Therefore, the bending strength of the joint part is equal to or higher than that of the main body, making it industrially practical.

In addition, when attaching the suspension fittings to the PC steel wire 8, the cutting tolerance of the PC steel wire can be adjusted by adjusting the tightening depth by screwing, which is convenient and prevents product gaps between the PC concrete piles.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional disc-type fitting, and Figures 2 and 3 are schematic diagrams of the tip of a PC steel wire. Figure 4 is a schematic cross-sectional view of the suspension fitting according to the present invention, and Figure 5 is a schematic diagram of its bottom view. FIG. 6 is a schematic cross-sectional view showing the case where the suspension fittings are attached by spot welding, and FIG. 7 is a PC in the case of Example 1.
This is a schematic front view of a concrete pile. 1...Disc metal fitting, 2...Cylindrical metal fitting, 3
...Suspension fittings, 8...PC steel wire.

Claims (1)

[Scope of utility model registration request] The suspension fitting 3 has a hole 4 into which a PC steel wire 8 is screwed in at the bottom, a screw hole 5 into which a tightening bolt is inserted and a flange 6 at the top. A concrete pile characterized in that it is attached to a disc part 1 of a joint fitting made of a thick plate.