JPS5853878Y2 - 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 to maintain the concrete in a compressed state and increase the bending stress, as shown in Figure 1A.
The insertion position of the C steel material is lowered to generate an upward distributed load 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.

As shown in Figure 1, a PC steel material 2 is placed below the concrete structure 1, and at the same time a steel material 4 with a raised central portion is inserted above, and a force in the compressive direction is applied to this steel material 4. Both ends are fixed to the ends of the concrete girder 1 (hereinafter, this steel material 4 will be referred to as a combrested steel material).

As a result, an upward distributed load P2 is applied to the concrete girder 1 by the combed steel material 4, and an upward distributed load of P1+P2 is applied to the concrete girder 1 as a whole.

On the other hand, the axial force applied to the concrete girder 1 becomes 0 as the center tensile force due to the combed steel material 4 and the center compressive force due to the PC steel material 2 cancel 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 a compressive force is applied to the combined 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 passing steel material through the edge of a concrete structure, which has low friction when inserting comb steel material, facilitates the injection of grout, and does not cause buckling of comb steel material during compression. Its purpose is to create a spiral-wound tube formed by winding a steel band material into a spiral shape, and to make the cross-section of the spiral-wound tube into a substantially elliptical shape at regular intervals along the longitudinal direction. The sheath for passing steel material in a concrete structure is characterized in that the deformed parts are formed such that the angles of the major axis of the ellipse are successively different between adjacent deformed parts.

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 is made into a tube by spirally winding a band-shaped steel material, and forming a helical joint 11 by interlocking and tightening the edges.

This sheath 10 has deformed portions 12 a at regular intervals.
, 12b are formed alternately.

These deformed parts 12 a and 12 b are crushed from the outer periphery of the tube to form an elliptical cross section, and the deformed parts 12 a and 12 b that are adjacent to each other have their long axis directions of the ellipses 90' apart from each other. They are formed sequentially.

When manufacturing this sheath 10, similar to conventional spirally wound pipe sheaths, a strip of steel is passed through a multi-stage molded roller, joint pieces that engage with each other are molded on both edges, and this is attached to a rotating core metal. The seam 11 is sequentially formed by winding it spirally and engaging the seam pieces with a caulking roller to form a continuous winding tube, and the winding tube is crushed in different directions at regular intervals to form a deformed portion 12a, 12b is formed.

The deformed portions 12 a and 12 b are located at a distance of 9 from each other in the major axis direction.
In addition to the 0° displacement, the direction may be sequentially changed to other angles.

In addition, numeral 13 in the figure indicates the inserted combreast steel material.

The sheath for passing steel materials of the present invention is constructed as described above, and the deformed portions each having a substantially elliptical cross section are sequentially formed by changing the angles of the deformed portions. 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 drawings]

Fig. 1A is an explanatory diagram of a conventional PC structure, the opening of Fig. 1 is an explanatory diagram of a structure using a combination of 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...
Seam, 12a, 12b... Deformed part, 13.
...Combreasted steel.

Claims (1)

[Scope of utility model registration request] A spirally wound tube formed by tightly winding a band-shaped steel material into a spiral shape is formed with deformed portions in which the cross section of the spirally wound tube has a substantially elliptical shape at regular intervals along the longitudinal direction, and the deformed portions are adjacent to each other. A sheath for steel materials in a concrete structure, characterized in that the angles of the major axis of the ellipse are sequentially different between the deformed parts.