JPH0633600A - Arrangement structure of pc steel in box rahmen - Google Patents

Abstract

PURPOSE:To minimize the cutting volume of a groove by means of water jet so as to improve the cutting efficiency. CONSTITUTION:PC steel 22 is arranged as shown by the dotted line in a box rahmen with reinforcement 12 buried therein. Namely, it is arranged in a covering inside the box at the straight line part, and at the corner angle part, it is eccentrically arranged in the outside section while insuring the coverting outside the box. Hereby, cutting by means of water jet is enough to be applied on concrete of the inside covering part at the straight line part of the box, so as to facilitate execution. Further, eccentric moment generated by eccentric arrangement of the PC steel 22 is reverse in the direction against bending moment by external load on the box rahmen 20, and hence this arrangement is effective for reducing deformation of the box rahmen 20 due to external load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to box ramen
The present invention relates to an arrangement structure of a PC steel material when reinforcing using a C steel material.

[0002]

[Prior art and its problems] As a technique for repairing and reinforcing a box culvert that has deteriorated over time due to rusting of reinforcing bars,
Cutting grooves in concrete with a water jet,
A method is known in which a PC steel material is placed in this groove and backfilled with mortar, and after the mortar hardens, the PC steel material is tensioned to prestress concrete. The method of cutting a groove with a water jet is excellent in that the water does not cut the reinforcing bar and only the concrete is cut, so that the stress transmission function of the reinforcing bar is not impaired.

However, in this method, as shown in FIG. 3, the concrete 14 on the back surface of the reinforcing bar 12 cannot be cut by simply injecting the water jet 10 from one direction, and this portion is cut to make the groove continuous. In order to do so, it is necessary to change the spray angle of the nozzle 16 and to cut it obliquely. That is, a separate process is required for cutting the concrete on the rear surface of the reinforcing bar, the cutting efficiency by the water jet is significantly reduced, and the economical efficiency of the reinforcing method by prestress is also impaired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the cutting volume of the groove by the water jet as much as possible by devising the arrangement structure of the PC steel material, thereby improving the cutting efficiency. .

[0005]

DETAILED DESCRIPTION OF THE INVENTION That is, according to the present invention, a box ramen is
In a structure reinforced with a C steel material, the PC steel material is arranged in a cover inside the box at a straight portion of the box frame, and eccentrically arranged in an outer cross section while ensuring a cover outside the box at a corner portion. It is characterized by having done.

[0006]

[Function] For cutting with a water jet, in the straight part of the box, only the concrete of the inner cover part is required, which facilitates the construction. Further, the eccentric moment generated by the eccentric arrangement of the PC steel material has a positive and negative sign opposite to the bending moment due to the external load applied to the box ramen, and has an effect of reducing the deformation of the box ramen due to the external load.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a preferred arrangement example of the PC steel material in the present invention, in which the PC steel material 22 is arranged as shown by the dotted line in the box ramen 20 in which the reinforcing bars 12 are embedded. As described above, the features of the arrangement structure of this PC steel material are (1) the straight part should be arranged inside the cover inside the box, and (2) the corner part should be outside while maintaining the cover outside the box. The eccentric arrangement in the cross section is two points.

Since the box ramen 20 is generally an underground structure, it has a fog of 6 to 7 cm, and the PC steel material 22 can be arranged in this space in the straight portion. Therefore, cutting with a water jet is required only for the concrete of the covering portion, the workability is good, and the work speed is improved.

On the other hand, in the corner portion, a centripetal force is applied to the PC steel material 22 due to the tension of the PC steel material 22, and the PC steel material 22 tends to slip out inside the cross section. Therefore, when the cover concrete is arranged in the same manner as the straight part, the cover concrete is sheared and broken. Therefore, the PC steel material 22 in the corner portion must secure the required cover thickness so that the cover concrete will not be broken by the centripetal force, and is arranged outside the cross section relative to the straight line portion. Become.

As a result, the PC steel material 22 is eccentrically arranged, and an eccentric moment acts on the box ramen 20 with tension. FIG. 2 illustrates this eccentric moment, and the box ramen 20 is symmetrical in the vertical and horizontal directions, and therefore the upper left portion 1/4 is modeled. In the figure, the alternate long and short dash line 24 indicates the centroid axis of the PC steel material, and the eccentric moment M is represented by the product of the tension force P and the eccentric amount e.

The eccentric moment M has the opposite sign to the bending moment due to the external load applied to the box rigid frame 20, and has the effect of canceling the external load. At this time, the eccentric moment amount increases as the eccentric amount e of the PC steel material 22 increases, so the PC steel material 22 is arranged outside the box as much as possible within a range where sufficient concrete fogging can be ensured on the outside of the cross section. It turns out that is advantageous.

FIG. 4 is an upper left 1/4 analytical model showing the distribution of prestress introduced by the PC steel material arrangement of FIG. In the figure, the line segment in each block represents the magnitude of the prestress applied.

FIG. 5 shows the deformation of the box ramen in the prestress distribution of FIG. 4, while FIG. 6 shows the deformation of the box ramen due to an external load.

FIG. 7 shows a situation in which the deformation due to the external load (FIG. 6) is suppressed by the bending moment acting in the opposite direction due to the introduction of prestress (FIG. 5). In this way, the box ramen can be effectively reinforced by the arrangement structure of the present PC steel material.

There is no particular limitation on the tension fixing means of the PC steel material 22, for example, a fixing block made of steel or reinforced concrete may be used, or the coupler fixing may be performed inside the box.

[0016]

According to the arrangement structure of the PC steel materials in the box ramen according to the present invention, the cutting capacity of concrete can be reduced and the construction cost can be reduced by adopting the new steel material arrangement.

Further, by arranging the PC steel material in an eccentric arrangement, a bending moment can be introduced into the box, and the bending moment is in the opposite direction to the bending moment generated by the external load, so that the sectional force due to the external load is reduced. be able to. As a result, the required amount of prestress is reduced, and the amount of PC steel can be reduced.

[Brief description of drawings]

FIG. 1 is a preferred layout of a PC steel material according to the present invention.

FIG. 2 is an explanatory diagram of an eccentric moment generated by an eccentric arrangement of PC steel.

FIG. 3 is a cross-sectional view showing a cutting situation of concrete by a water jet.

FIG. 4 is an analytical model showing the distribution of prestress introduced by the PC steel arrangement of FIG.

FIG. 5 is a diagram showing a deformed state of the box ramen in the prestress distribution shown in FIG.

FIG. 6 is a diagram showing a state of deformation of a box ramen due to an external load.

FIG. 7 is a diagram showing a situation in which the deformation due to an external load is suppressed by the introduction of prestress.

[Explanation of symbols]

 12 Reinforcing bar 20 Box ramen 22 PC steel

Front page continuation (72) Inventor Toshiyuki Tachibada 2-1, Tsukudo-cho, Shinjuku-ku, Tokyo Kumagaya Gumi Tokyo Head Office (72) Inventor Tsutomu Honda 2-1-1 Tsukudo-cho, Shinjuku-ku, Tokyo Kumagaya Gumi Tokyo In-house (72) Inventor Yusuke Matsushita 2-1, Tsukudo-cho, Shinjuku-ku, Tokyo Kumagaya Gumi Tokyo Head Office (72) Inventor Tetsuya Kumasaka 2-1-1 Tsukudo-cho, Shinjuku-ku, Tokyo Kumagai Gumi Tokyo Head Office

Claims (1)

[Claims] 1. In a structure in which a box ramen is reinforced with a PC steel material, the PC steel material is arranged in a cover inside the box at a straight portion of the box ramen and a cover outside the box is secured at a corner portion. Meanwhile, the arrangement structure of the PC steel material is characterized in that it is arranged eccentrically in the outer cross section.