JPH0337603B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a structure having a length extending over a plurality of underground floors and which is built into the ground prior to the construction of each basement floor in the reverse construction method. Regarding pillars.

The reverse construction method is a construction method in which multiple underground floors are built sequentially from above to below by repeatedly excavating the ground below the structure while supporting the structure using the structural pillars mentioned above. be. Since this construction method allows the construction of underground and above-ground sections to proceed at the same time, it is often adopted, especially in buildings with many underground floors, as it can shorten the construction period and reduce costs accordingly. ing.

[Conventional technology]

The structural pillars used in this reverse construction method are conventionally known to be made of steel, such as structural rolled steel, or a combination thereof. The construction of these structural pillars is carried out by constructing cast-in-place concrete piles, inserting the structural pillars into the tops of these piles immediately after the concrete is placed, and fixing them as the concrete hardens. be.

[Problem that the invention seeks to solve]

However, in the case of the conventional configuration described above, there were problems as described below, and there was room for improvement.

In other words, even though the building itself is made of reinforced concrete, if the reverse construction method is adopted due to construction requirements such as the construction period, steel columns must be prepared as the structural pillars for temporary construction. Since steel columns are buried in concrete and cannot be reused, they are expensive.

In addition, if the building is made of steel-framed reinforced concrete, the columns of the structure of the building itself can be used as structural pillars for the reverse casting method, but the concrete parts of the columns are horizontally hammered for each basement floor. This resulted in joints, which could lead to deterioration in quality due to deterioration in construction accuracy. This problem also occurs in the case of the above-mentioned reinforced concrete building.

Furthermore, since the structural pillars are made of steel, if they are to be used in conjunction with reinforced concrete piles, the only way to fix them is to embed the steel columns in concrete, and reinforced concrete piles are limited to cast-in-place piles. Ta.

In view of the above-mentioned circumstances, the object of the present invention is to eliminate the risk of deterioration in quality due to horizontal pouring of concrete when used in the reverse pouring method, and to be suitable for use in reinforced concrete buildings. The aim is to provide a core structure that does not increase costs.

[Means for solving problems]

The characteristic structure of the structural column according to the present invention is that the structural column main body is formed from reinforced concrete, and the outer circumferential surface of the connection point with the horizontal members of each basement floor has uneven parts that support the horizontal members and transmit stress. The reason lies in the fact that it was formed.

[Effect]

In other words, in uneven areas, stress is sufficiently transmitted from the horizontal members that make up each basement floor to the structural pillars, so reinforced concrete as the structure of the building itself has a length that spans multiple basement floors. Ready-made columns can be used as a support for the framework and working load when constructing an underground framework by the reverse casting method.

Furthermore, since the main body of the structural column is made of ready-made reinforced concrete, when using reinforced concrete piles, cast-in-place concrete piles can be used in the same way as the cement milk method, and ready-made concrete can be used in the same way as pile welding. The structure pillars can be fixed to the respective piles.

〔Effect of the invention〕

As a result, by using prefabricated reinforced concrete piles that are long enough to span multiple basement floors, it is possible to eliminate the need to cast concrete for columns on-site when constructing each basement floor, shortening the process, and It is now possible to avoid the deterioration in quality caused by the large number of horizontal pour joints.

Furthermore, even if the building is constructed of reinforced concrete, there is no need to use temporary steel columns only for the reverse construction method, which was required in the past, so construction can be carried out extremely cost-effectively.

Furthermore, since it can be used in conjunction with ready-made concrete piles, it is also possible to construct both in a single process with both welded together, further shortening the construction period.

Therefore, as a whole, it has become possible to perform the reverse pouring method at a cost advantage while maintaining good quality and shortening the construction period.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Figure 3 is a cross-sectional view of a two-story underground floor constructed using the reverse construction method. Reference numeral 1 designates a structural column whose main body 1a is made of prestressed reinforced concrete formed by centrifugal force, and has a length equivalent to two layers. 2 is a cast-in-place concrete pile. After constructing the concrete pile 2, the standing pillar 1 is inserted into the upper part of the pile while the concrete has not yet hardened, and as the concrete hardens, the pillar 1 is fixed.

In the figure, 3a, 3b, and 3c are slabs for the first floor, first basement floor, and second basement floor, respectively, and are so-called flat slabs that are connected and fixed to the structural column 1 via column capital enlarged parts 4a, 4b, and 4c. It is becoming. The fixing structure between the slabs 3a to 3c and the structural pillar 1 will be further explained.

As shown in FIGS. 1 and 2, an uneven portion A is formed on the outer peripheral surface of the structural column 1 at a location where the slabs 3 of a certain floor are connected. Specifically, the diameter d _A of the column at this location is made smaller by the diameter d _O of the column at locations other than where the slab 3 is connected, and a checkered cotter 5 is further placed on the outer peripheral surface of this small diameter portion. It has been formed. In the figure, 6 is a steel plate for reinforcing the edge of the concrete supporting the slab 3, 7 is a fixing anchor for fixing this plate 6, and 8 is a tendon or reinforcing bar.

Next, a process of constructing a plurality of underground floors using the structural pillar 1 using the reverse construction method will be explained.

First, a continuous wall 9 that serves as a heap is formed on the ground G around the planned construction site. (See Figure 4 A). Next, multiple concrete piles 2 were installed at the planned construction site.
construction. This concrete pile 2 is a cast-in-place concrete pile constructed by injecting concrete C through a tremie pipe 11 or the like into a vertical hole H that has been excavated with an earth auger (not shown) and filled with bentonite liquid 10 ( (See Figure 4b).

Then, the structural pillar 1 in an upright state suspended by a crane 12 is inserted into the upper end of this concrete pile 2,
Wait for the concrete on pile 2 to harden. This structure pillar 1
As mentioned earlier, the main body 1a is made of precast concrete formed by centrifugal force, and uneven portions A are formed on the outer circumferential surface at locations corresponding to the positions of each floor (see Figure 4 C). .

Thereafter, excavation of the ground G is started, and the formwork 14 for the first floor slab is installed in a state where it is supported via the pipe support 13 on the root cut B for one layer (see FIG. 4D). After reinforcing is placed in the formwork 14, concrete is placed, and after the concrete has developed its strength, the pipe support 13 and the formwork 14 are removed, and the area below them is excavated. By repeating this process, construction of a plurality of underground floors progresses, starting from the first basement floor and then to the second basement floor, starting from the upper floors to the lower floors. At this time, the construction of the ground structure S is also being carried out in parallel (see Figure 4, E).

Stress is effectively transmitted from the slope 3 of each floor to the structural pillar 1 via the uneven part A, and the structural pillar 1, which is also a permanent structural column, supports the working load during construction along with the frame. It is becoming possible to do so. Finally, the construction of the basement floor is completed by pouring concrete for the bottom plate 15 (see Fig. 4).

In addition, in the previous embodiment, the column capital enlarged portion 4 is provided on the structural column 1.
A so-called flat slab structure in which the floor slabs 3 are directly connected via the floor slabs has been described. Alternatively, the structural column 1 according to the present invention can also be used in a commonly used structure in which a floor slab is connected to a beam, and this beam is connected to a column. The slab 3 and the beam are referred to as horizontal members 3.

Further, the specific structure of the concave-convex portion A that contributes to the connection between the structural pillar 1 and the horizontal member 3 can be changed as needed, and a modified example thereof will be described next.

As shown in FIGS. 5 and 6, a plurality of brackets 16a and 16b are welded to the connection point of the main column body 1a made of prestressed concrete with the flat slab 3 as a horizontal member, with the brackets 16a and 16b protruding from the inner and outer surfaces. A steel pipe 17 made of aluminum is fitted onto the outside. In other words, each bracket 16a protruding from the inner surface allows
The steel pipe 17 and the structural pillar main body 1a are integrated,
An uneven part A is formed by each bracket 16b protruding from the outer surface, and when the concrete of the flat slab 3 is poured, the uneven part A effectively transmits stress from the flat slab 3 to the structural column 1. It is configured so that 8 in the figure is a tendon material.

In the previous embodiment, the construction pillar 1 was inserted into the cast-in-place concrete pile 2 and fixed therein. Instead, a joint steel pipe is fitted onto the lower end of the structural column 1, and this steel pipe and a joint steel pipe fitted onto the upper end of the prestressed concrete pile are integrated by welding. It may be built into the ground G in the step of . In this case, it becomes possible to further shorten the process.

Furthermore, the cross-sectional shape of the structural pillar 1 in the previous embodiment was circular because it was formed by centrifugal force, but it may alternatively have a cross-sectional shape such as a square or a polygon. Moreover, its length can also be changed as appropriate depending on workability and the like.

[Brief explanation of the drawing]

The drawings show an embodiment of the structural pillar according to the present invention, FIG. 1 is an enlarged side view of the main part of the structural pillar, FIG. 2 is a cross-sectional view taken along the line - in FIG. 1, and FIG. 3 is a cross-sectional view of the underground floor. Figures 4A to 4F are cross-sectional views showing the construction process of the basement floor, Figure 5 is a side view corresponding to Figure 1 showing another embodiment, and Figure 6 is a cross-sectional view taken along the - line in Figure 5. It is. 1a...Main pillar body, 3...Horizontal member, A...
Uneven parts.

Claims (1)

[Scope of Claims] 1. A structural pillar that has a length extending over a plurality of underground floors and is built into the ground prior to the construction of each basement floor in the reverse construction method, and which has a structural pillar main body 1a. The structural column is made of reinforced concrete and has uneven parts A formed on the outer circumferential surface of the connection points with the horizontal members 3 of each basement floor to support the horizontal members 3 and transmit stress. 2. The structural pillar according to claim 1, wherein the reinforced concrete is formed by centrifugal force forming.