JPS6336105Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to measures to prevent cracks caused by thermal stress in a concrete wall on the top floor that supports a roof slab.

In general, the roof slab is also a kind of large heat absorption plate that absorbs solar heat, so the temperature difference between the roof slab and the floor slab during the daytime is quite large. Therefore, while the bottom end of the concrete wall on the top floor is fixed, the top end is pulled in the span direction due to the thermal expansion of the roof slab, creating stress, and this thermal stress causes stress. Cracks may occur. As shown in FIG. 1, these cracks occur diagonally, and the range in which they occur is at most a wall portion located about 1/4 of the span l from both ends in the span direction.

By the way, cracks caused by thermal stress can also be prevented by placing multiple diagonal reinforcements perpendicular to the direction of the crack, but in this case, diagonal reinforcement is applied to each wall reinforcement that is double reinforced. Tying the threads one by one is a very tedious task and requires skill.

Therefore, the present invention has been developed to prevent cracks caused by thermal stress without causing such inconvenience. Moreover, it is characterized by the fact that expanded metal is buried in the middle of each double-reinforced wall reinforcement.

According to this configuration, since the expanded metal with the required dimensions is used in advance, there are fewer tying points compared to tying diagonal reinforcing bars one by one, and there is no disorder in the reinforcement arrangement. Therefore, it is easy to work with and does not require skill. Furthermore, since expanded metal is only installed in the middle of wall reinforcements that are double reinforced, that is, in the center of the wall thickness, the procedure is such that after placing reinforcement on one side, reinforcement is placed on the other side. It is only necessary to add the step of arranging the expanded metal to the double reinforcement process carried out by the company, and it can be manufactured easily without drastically changing the conventional work procedure. For example, when placing expanded metal on the outside of wall reinforcements, if a predetermined concrete covering thickness is secured for the wall reinforcements on the expanded metal side, the concrete covering thickness for the expanded metal will be insufficient.
On the other hand, if a predetermined covering thickness is secured for the expanded metal, the wall reinforcement on the expanded metal side will shift inward by the thickness of the expanded metal, and the distance between it and the wall reinforcement on the other side will become narrower, reducing cross-sectional performance. Moreover, because the expanded metal and the wall reinforcement have to be in close contact due to the relationship with cross-sectional performance and covering thickness, problems arise such as poor circulation of the poured concrete.

According to the present invention, such problems can also be solved.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 2 conceptually shows the planar shape of the top floor of a medium-to-high-rise building, and FIG. 3 conceptually shows the concrete wall 1 in the span direction of the top floor. Fourth
The figure shows the cross-sectional shape of the concrete wall 1, and 2
a... is wall reinforcement on one side arranged in a vertical and horizontal lattice pattern, 2
b... are wall reinforcements on the other side that are similarly arranged, and the expanded metal 3 is buried in the middle part of these wall reinforcements 2a..., 2b.... The upper ends of the expanded metals 3... are tied to the braces 4 of the beams. 5 is the beam main reinforcement, and 6 is the beam steel frame.

The expanded metal 3... is attached to the concrete wall 1 as shown by the diagonal grid-like broken lines in FIG.
It is buried only in the wall part located about 1/4 of the span from both ends of the span.

With the above configuration, cracking of the concrete wall 1 due to thermal stress can be prevented.

The above crack prevention structure is effective whether the concrete wall 1 is made of cast-in-place concrete or a precast concrete product.

[Brief explanation of the drawing]

Figure 1 is an illustration of cracks caused by thermal stress, Figure 2
4 to 4 show an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view, FIG. 3 is a schematic front view, and FIG. 4 is a longitudinal sectional view of the main part. 1... Concrete wall, 2a, 2b... Wall reinforcement,
3... Expanded metal.

Claims (1)

[Scope of utility model registration request] The part of the concrete wall on the top floor that spans about 1/4 of the span from both ends in the span direction.
A structure for preventing cracks in a concrete wall on the top floor, characterized in that expanded metal is buried in the middle part of each double-reinforced wall reinforcement.