JPS5853877Y2 - Sheath for rolling steel materials in concrete structures - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sheath for inserting a steel material into a concrete structure, through which a steel material is inserted to apply a force in a tensile direction to the inside of the concrete structure.

Generally, in prestressed concrete, a tensile so-called prestressing steel material 2 is inserted into the inside of a concrete girder 1, as shown in Figure 1A, to keep the concrete in a compressed state and increase bending stress.
The C steel material insertion position is lowered to create an upwardly distributed cargo storage P1 at the center of the girder.

On the other hand, in recent years, a construction method has been developed in which a force in a direction opposite to the compression by the above-mentioned PC steel material, that is, a force in a tensile direction, is applied to a concrete structure to generate an upward distributed load.

This is done by placing the PC steel material 2 into the concrete 1 as shown in the opening of Figure 1.
-Structure vIJ1 is placed below and at the same time, a steel material 4 with a raised central portion is inserted into the upper side, a force in the compressive direction is applied to this steel material 4, and both ends are fixed to the ends of the concrete I/girder 1 ( Hereinafter, this steel material 4 will be referred to as a combined steel material).

As a result, an upward distributed load P2 is applied to the conchnaut girder 1 by the combination steel material 4 as well, and an upward distributed load of P 1 + P 2 is applied as a whole.

On the other hand, the axial force applied to the concrete girder 1 becomes O due to the central tensile force due to the combed steel material 4 and the central compressive force due to the PC steel material 2 canceling each other out, but the bending stress components result in addition to each other.

Therefore, by appropriately selecting the tensile force of the prestressed steel material 2 and the compressive force of the combined steel material 4, the dead load applied to the conchnaut girder 1 was canceled out, thereby reducing the girder height and increasing the span. be.

In such a construction method, a sheath for inserting the combed steel material 4 is buried in the concrete girder 1 in advance, but this sheath is such that the combed steel material 4 can be inserted easily and the sheath is suitable for grouting. In order to satisfy conditions such as ease of use, the diameter needs to be large to a certain extent.

However, when a conventional sheath is used, lateral displacement, ie, buckling, occurs within the sheath when compressive force is applied to the combed steel material, and the desired compressive stress may not be obtained.

In view of the above-mentioned points, the present invention provides a sheath for inserting steel materials in concrete structures, which has low friction when inserting combed steel materials, makes it easy to inject grout, and does not cause buckling of combed steel materials when compressed. The purpose of this project is to create a spiral-wound pipe that is formed by spirally winding a steel strip with continuous uneven stripes in the longitudinal direction. A deformed portion is formed in which the cross section of the spirally wound tube is approximately elliptical, and the deformed portions are formed such that the angles in the major axis direction of the ellipse are sequentially different between adjacent deformed portions. Existing in sheaths for inserting steel materials in concrete structures.

Next, an example of the implementation of the present invention will be explained with reference to the drawings from FIG. 2 onwards.

10 in the figure is a sheath for passing steel material according to the present invention.

This sheath 10 has a plurality of protrusions 11 in the longitudinal direction of the steel strip.
, 11, .

This sheath 10 has deformed portions 13 a at regular intervals.
, 13b are formed alternately.

These deformed parts 13a and 13b are crushed from the outer periphery of the tube to form an elliptical cross section, and the deformed parts 13a and 13b that are adjacent to each other are sequentially shaped so that the long axis direction of the ellipse is different by 90 degrees from each other. It is formed.

When manufacturing this sheath 10, similarly to conventional spirally wound pipe sheaths, a strip-shaped steel material is passed through multistage forming rollers, and joint pieces that engage with each other are formed on both edges thereof, and at the same time, protrusions 11, 11 are formed. Then, this is wound spirally around a rotating core metal, and while the seam pieces are engaged, seams 12 are sequentially formed using a caulking roller to form a continuous winding tube, and the direction of the winding tube is changed at regular intervals. and crush it to form deformed parts 13a and 13b.

The deformed portions 13a and 13b may not only be displaced by 90 degrees in the major axis direction, but may also be sequentially displaced at other angles.

In addition, numeral 14 in the figure is the inserted combreast steel material.

The steel material insertion seam of the present invention or the combreasted steel material inserted into the interior is formed by sequentially forming deformed parts having approximately elliptical cross sections and changing their angles as described above. Since the elliptical short diameter part is sandwiched only from two directions, there is less friction during insertion, and the grout can be injected more smoothly than in the long diameter space, and each deformed part is held in the long diameter direction. Because the angles of the deformed parts are different in adjacent deformed parts, the combined steel material can be clamped not only from one direction but from multiple directions, which has the effect of being less prone to buckling when compressed. It is.

[Brief explanation of the drawing]

Fig. 1A is an explanatory diagram of a conventional PC structure, the opening of Fig. 1 is an explanatory diagram of a structure using both prestressed steel and combined steel, Fig. 2 is a side view showing an example of the implementation of the present invention, and Fig. 3 is an explanatory diagram of a conventional PC structure. I in Figure 2
4 is a sectional view taken along line II-II in FIG. 2. 10... Steel material insertion sheath, 11...
Projection, 12... Seam, 13 a, 13 b.
...Deformed part, 14...Combreasted steel material.

Claims (1)

[Scope of utility model registration request] A spirally wound tube formed by spirally winding a strip steel material with continuous unevenness in the longitudinal direction, and a modification in which the cross section of the spirally wound tube is made approximately elliptical at regular intervals along the lengthwise direction. What is claimed is: 1. A sheath for passing combed steel material, characterized in that the deformed portions are formed such that the angles in the major diameter direction of the ellipse are sequentially different between adjacent deformed portions.