JPH05295786A - Arranging structure of pc-steel in box rahmen - Google Patents

Abstract

PURPOSE:To effectively reinforce the corner angle part of a box rahmen by means of PC-steel. CONSTITUTION:Against usual figure center arrangement shown by a dotted line in PC-steel arrangement of a box rahmen, the PC-steel is arranged in the position to give uniform axial force in the straight line part, and eccentrically arranged inside the dotted line part at the corner angle part. By arranging the PC-steel in this way, nearly equal prestress to that of the straight line part is given to the corner angle part, and hence an arch-like corner angle part having nearly equal thickness to that of the straight line part can be obtained.

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]

2. Description of the Related Art For example, when repairing a box culvert that has deteriorated over time due to rusting of reinforcing bars, etc., as shown in FIG.
As shown in the cross-sectional view of FIG. 1, since the main tensile reinforcement is inside the side wall, it is possible to repair it by chipping it out and reattaching a new reinforcement. However, since the main tensile reinforcing bars are on the outside at the corners of the box culvert, almost all of the concrete cross section is chipped to repair and repair this, which is not possible.

Also, by pre-casting a steel plate or a steel plate on the inner surface of the culvert, or by staking concrete,
A method of covering the deterioration of the tensile main reinforcing bar by increasing the cross-section can be considered, but this method has a drawback that the usable space in the tunnel is narrowed.

Therefore, it is conceivable to introduce prestress for the purpose of reinforcing the outside of the corner portion. The introduction of pre-stress can be achieved by cutting the groove with a water jet, inserting a PC steel material into the groove, back-filling it, and then fixing the tension. At this time, since the bending moment distribution of the box culvert is as shown in FIG. 7, it is usually advantageous to arrange the PC steel materials in an eccentric arrangement as shown in FIG. However, in such an arrangement, since the PC steel material passes through the outside at the corner portion, almost all of the concrete cross section is eventually cut off, which is not possible.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an arrangement structure of PC steel materials which is effective to reinforce the corners based on the concept of a new reinforcing design of a box frame structure.

[0006]

That is, the present invention relates to a structure in which a box ramen having a haunch is reinforced with a PC steel material,
It is characterized in that the PC steel material is arranged at a position where a uniform axial force is applied in the straight portion of the box ramen, and is eccentrically arranged inside the straight portion in the corner portion.

[0007]

[Operation] By arranging the PC steel materials as described above,
The corner portion of the box ramen is prestressed to be approximately equal to that of the straight portion, and an arched corner portion having a thickness substantially equal to that of the straight portion can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. Figure 1 is a PC steel material layout of box ramen,
The dotted line indicates the normal centroid arrangement. As mentioned above,
This PC steel material arrangement is characterized in that (1) it is arranged at a position that gives a uniform axial force in the straight line portion, and
(2) The two points are that the corner portion is eccentrically arranged inside the straight portion.

Since (1) has a statically indeterminate structure in which the box ramen is closed, the PC steel material does not necessarily have to be placed in the center of gravity, and is separated from the center of gravity by an eccentric distance that gives a constant eccentric moment. Means that you may. For example, if the box ramen has the same thickness, they may be arranged at positions equidistant from the centroid (parallel to the centroid axis).

(2) requires the PC steel material to be placed inside the cross section of the PC steel material axial line of the straight line portion determined in (1). In this case, the eccentric distance is measured approximately at right angles to the PC steel material. About 1/6 to 1/4 of the member width is preferable.
This roughly corresponds to arranging the distance from the inside of the cross section of the PC steel material along the haunch also in the corner portion at a distance similar to that of the straight portion.

Next, it will be explained that, due to the above PC steel material arrangement, substantially the same prestress as that of the straight line portion is introduced into the corner portion within substantially the same thickness as that of the straight line portion. FIG. 2 shows an example of the arrangement of PC steel material in the corners, where the dotted line is the normal centroid arrangement, and the broken line and the alternate long and short dash line are the arrangements eccentrically inward by h / 6 and h / 3, respectively. Showing.

FIG. 3 is a distribution model of the prestress that changes depending on the arrangement of the PC steel materials in FIG. 2. Now, the uniform prestress shown as a ● distribution is introduced in the straight line portion. On the other hand, in consideration of the haunch, the corner portion has a cross-sectional area close to double that of the straight portion, so that the prestress introduced is smaller than that of the straight portion. The pre-stress distribution is not uniform because the cross-sectional area originally changes continuously at the corners, but here, as a simple model, the cross-sectional area is twice that of the straight line, and the pre-stress distribution shown in Figure 3 is used. It is assumed that the stress has a uniform distribution of 1/2 of the linear portion. Although this assumption is different from reality, it is an approximation for ease of explanation.

Therefore, when the PC steel material is decentered by h / 6 at the corners, the prestress distribution becomes larger on the inner surface as the distribution ▲ in FIG. 3 and becomes a uniform distribution in the straight line portion (distribution ● in FIG. 3). Get closer. If the amount of eccentricity is about h / 6 to h / 4, it can be considered that the straight line portion and the corner portion have almost the same width and the substantially uniform prestress is distributed.

In the PC steel material arrangement of the present invention described above, no prestress is applied to the outside of the corner portion, so the concrete in this portion is not reinforced. Therefore, the cracks formed on the outside of the corner portion remain or progress without being repaired, and the concrete on the outside of the corner portion becomes a state that should be ignored. On the other hand, inside the corner, there is a healthy part that is sufficiently reinforced by prestressing, and the thickness is about the same as the straight part. Therefore, while the normal structural model of a normal box lamen has a rectangular shape as shown in FIG. 4A, the reinforced structural model according to the present invention has the structure shown in FIG.
As shown in (b), the corners have no arched corners, ignoring the prestressed portions outside the corners.

FIG. 5 shows an example of a sectional force distribution calculated by applying the same load to the structural models shown in FIGS. 4 (a) and 4 (b). In the figure, (a) and (b) represent the distribution of the bending moment, and the structural model (b) of the present invention.
In comparison with the normal structural model (a), the bending moments in the upper and lower corners are reduced by about 40% each. Further, FIGS. 5C and 5D show the distribution of the axial force, and the structural model (d) of the present invention has a higher axial force than the normal structural model (c) and a lower axial force. 10%
It is increasing.

This is a result of the arch structure of the corners bearing the load as an axial force and reducing the bending moment. That is, it has been shown that by reinforcing the PC steel material arrangement of the present invention, the box ramen can be mechanically converted into a more advantageous structure, and such PC steel material arrangement is performed to introduce prestress. However, it can be seen that it is extremely effective as a reinforcement measure.

[0017]

According to the arrangement structure of PC steel materials in the box ramen according to the present invention, by adopting a new steel material arrangement, it is difficult to reinforce by a method other than widening the cross section to the air side in the existing tunnel. It is possible to effectively reinforce the corners.

[Brief description of drawings]

FIG. 1 is a PC steel material layout of a box ramen.

FIG. 2 shows an example of arrangement of PC steel material in a corner portion.

FIG. 3 is a distribution model of prestress that changes depending on the arrangement of PC steel.

FIG. 4 shows a structural model of box lamene,
The figure (a) is a normal healthy structural model, and the figure (b) is a reinforced structural model according to the present invention.

FIG. 5 is a sectional force distribution diagram when the structural models of FIGS. 4A and 4B are used.

FIG. 6 is a cross-sectional view showing a bar arrangement in a conventional box culvert.

FIG. 7 is a bending moment distribution diagram of a box culvert.

FIG. 8 is an advantageous layout of PC steel in a box culvert.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Tachibada No. 2 Tsukuto-cho, Shinjuku-ku, Tokyo Kumagai Gumi Tokyo Head Office (72) Inventor Tsutomu Honda No. 2 Tsukuto-cho, Shinjuku-ku, Tokyo Kumagai Gumi Tokyo Head Office (72) Inventor Tetsuya Kumasaka 2-1, Tsukudocho, Shinjuku-ku, Tokyo Kumagai Gumi Tokyo Head Office

Claims (1)

[Claims] 1. A box ramen with a haunch is a PC
In a structure for reinforcing using a steel material, the box steel frame is characterized in that the PC steel material is arranged at a position where a uniform axial force is applied in the straight portion of the box ramen, and the corner portion is eccentrically arranged inward of the straight portion. Arrangement structure of PC steel in.