WO2021149266A1

WO2021149266A1 - Building construction method

Info

Publication number: WO2021149266A1
Application number: PCT/JP2020/005366
Authority: WO
Inventors: 貴穂河野; 全高尾; 健太郎石井; 慎行谷; 研二山口
Original assignee: 株式会社竹中工務店
Priority date: 2020-01-22
Filing date: 2020-02-12
Publication date: 2021-07-29
Also published as: JP2021116528A; JP6682173B1

Abstract

This building construction method comprises: a step for constructing a foundation on an excavation surface obtained by excavating a ground; a step for erecting, above the foundation, a plurality of columnar bodies constituting a part of an underground core part; a step for connecting the capitals of the columnar bodies to construct a wall-shaped aboveground core part above the columnar bodies; a step for constructing an aboveground framework around the aboveground core part while constructing the aboveground core part; and a step for, while constructing the aboveground core part, constructing an underground framework around the columnar bodies, and constructing other parts of the underground core part in order from the lower side to construct a wall-shaped underground core part.

Description

How to build a building

This disclosure relates to the construction method of the building.

Japanese Unexamined Patent Publication No. 2017-172262 describes a method for constructing a building in which an elevator shaft is constructed in advance and then a skeleton is constructed around the elevator shaft.

In the building construction method shown in JP-A-2017-172262, the elevator shaft is first constructed first, and then the skeleton is constructed sequentially from the bottom to the top. Therefore, the construction period may be longer than when the elevator shaft is not constructed in advance. In particular, when constructing a building with a basement floor, it is necessary to excavate the ground prior to the construction of the elevator shaft, so that the construction period becomes even longer.

This disclosure provides a method for constructing a building that can shorten the construction period when constructing a building with a core structure having a basement floor.

The building construction method of the first aspect includes a step of constructing a foundation on an excavated surface excavated from the ground, a step of erection of a plurality of columnar bodies forming a part of an underground core portion above the foundation, and the columnar column. A step of connecting the stigmas of the body to construct a wall-shaped above-ground core portion above the columnar body, a step of constructing the above-ground skeleton around the above-ground core portion while constructing the above-ground core portion, and the above-mentioned It includes a step of constructing an underground skeleton around the columnar body while constructing the above-ground core portion, and sequentially constructing other portions of the underground core portion from the lower side to construct the wall-shaped underground core portion. ..

In the building construction method of the first aspect, first, a plurality of columnar bodies forming a part of the underground core portion are erected above the foundation. Next, the above-ground core portion is constructed using this columnar body as a support structure. Further, while constructing the above-ground core portion, the above-ground skeleton, other parts of the underground core portion, and the underground skeleton are constructed. That is, in a core structure building with a basement floor, the skeleton can be constructed at the same time. Therefore, the construction period can be shortened as compared with the case where the above-ground skeleton is sequentially constructed after the construction of the underground skeleton.

Also, the columnar body that supports the above-ground core is part of the underground core. That is, the columnar body can be used as the main member. Therefore, the man-hours related to the removal can be reduced as compared with the case where the columnar body is formed by the temporary member.

Furthermore, the underground core part is constructed by separating the columnar body and other parts. Therefore, a girder for holding the retaining wall of the excavated surface can be passed between the columnar bodies until the other portion is constructed. As a result, it is possible to reduce work such as replacement and replacement of cutting beams. In addition, the horizontal spacing of the girders can be narrowed as compared with the case where the girders are constructed while avoiding the entire underground core portion. Therefore, it is possible to reduce the reinforcement of the girder and the abdomen.

In the method of constructing the building of the second aspect, in the method of constructing the building of the first aspect, the columnar body is formed of precast concrete, and the underground core portion is formed by placing concrete between the adjacent columnar bodies. It is formed.

According to the building construction method of the second aspect, the columnar body is formed of precast concrete. Therefore, the columnar body can be started up more quickly than when it is formed of cast-in-place concrete. As a result, the effect of shortening the construction period can be enhanced.

In the method of constructing the building of the third aspect, in the method of constructing the building of the first aspect or the second aspect, the columnar body is added while constructing the above-ground core portion.

According to the building construction method of the third aspect, when the weight of the above-ground core part increases with the construction of the above-ground core part, a columnar body is added. As a result, the construction of the above-ground core portion can be started at the stage where the number of columnar bodies is smaller than the number of columnar bodies finally required. That is, the construction of the above-ground core portion can be started at an early stage. Therefore, the effect of shortening the construction period can be enhanced.

According to this disclosure, the construction period can be shortened when constructing a core structure building with a basement floor.

It is a vertical cross-sectional view which shows the building constructed by the construction method of the building which concerns on embodiment of this disclosure. FIG. 3 is a cross-sectional view taken along the line BB in FIG. 1A. It is a vertical cross-sectional view which shows the state which excavated the ground and formed the mountain retaining wall in the building construction method which concerns on embodiment of this disclosure. FIG. 2 is a cross-sectional view taken along the line BB in FIG. 2A. It is a vertical cross-sectional view which shows the state which the columnar body was erected above the foundation deck in the building construction method which concerns on embodiment of this disclosure. FIG. 3A is a cross-sectional view taken along the line BB in FIG. 3A. FIG. 5 is a vertical cross-sectional view showing a state in which a above-ground core portion is constructed above a columnar body and an underground skeleton is constructed around the columnar body in the building construction method according to the embodiment of the present disclosure. FIG. 4A is a cross-sectional view taken along the line BB in FIG. 4A. FIG. 5 is a vertical cross-sectional view showing a state in which a driving portion is formed between columnar bodies and an underground core portion is sequentially constructed from the lower side in the building construction method according to the embodiment of the present disclosure. It is a vertical cross-sectional view which shows the state which added the columnar body in the building construction method which concerns on embodiment of this disclosure. It is a top view which shows the modification which formed the columnar body in a substantially L shape in the building construction method which concerns on embodiment of this disclosure. It is a top view which shows the modification which formed the columnar body thinner than the thickness of the underground core part in the building construction method which concerns on embodiment of this disclosure. It is a top view which shows the modification which formed the columnar body with H-shaped steel in the building construction method which concerns on embodiment of this disclosure. FIG. 5 is a vertical cross-sectional view showing a modified example of constructing a floor close to the ground prior to a floor close to the foundation deck of the underground skeleton in the building construction method according to the embodiment of the present disclosure. It is a vertical cross-sectional view which shows the modification which constructs the 1st floor slab prior to the underground skeleton in the building construction method which concerns on embodiment of this disclosure. 8A is a cross-sectional view taken along the line BB in FIG. 8A.

Hereinafter, the method of constructing the building according to the embodiment of the present disclosure will be described with reference to the drawings. The components shown by using the same reference numerals in each drawing mean that they are the same components. Unless otherwise specified in the specification, each component is not limited to one, and a plurality of components may exist. In addition, description of overlapping configurations and symbols in the drawings may be omitted. The present disclosure is not limited to the following embodiments, and may be carried out with appropriate changes such as omitting the configuration or replacing it with a different configuration within the scope of the purpose of the present disclosure.

<Building>
As shown in FIGS. 1A and 1B, the building 10 to which the building construction method according to the embodiment of the present disclosure is applied is, for example, a center core type reinforced concrete structure (hereinafter, “RC structure (Reinforced-Concrete structure)”). It is a building of).

The "center core type" is a structural type in which a tubular skeleton (that is, a core part) extending in the vertical direction is formed in the central part of the building. In addition to seismic elements such as seismic walls and brace, staircases, elevators, equipment piping, etc. are arranged in the core part. Further, around the core portion, an outer peripheral portion supported by the core portion is constructed.

In the building 10, an outer peripheral portion 30 is constructed around the core portion 20. The core portion 20 is an RC skeleton, and includes an underground core portion 22 and an above-ground core portion 24. The underground core portion 22 and the above-ground core portion 24 have the same shape in a plan view. Further, the underground core portion 22 and the above-ground core portion 24 are integrally formed.

Although not shown in FIGS. 1A and 1B, a partition wall for partitioning the above-mentioned staircase, elevator, equipment piping, etc. is constructed inside the core portion 20. Further, inside the core portion 20, a slab is constructed for the user of the building 10 to walk or place a load. Further, an opening is appropriately formed in the concrete wall forming the core portion 20 so that the user of the building 10 can move between the inside and the outside of the core portion 20.

As an example, the outer peripheral portion 30 includes a beam 32 supported by the core portion 20 and projected from the core portion 20, a slab 34 supported by the beam 32, and an outer wall 36 supported by the slab 34. Has been done.

A small beam (not shown) can be hung on the beam 32. Further, the thickness of the slab 34 can be adjusted to omit the beam 32. Further, columns and walls can be appropriately constructed between the vertically adjacent beams 32 or slabs 34.

The outer wall 36 is formed by a curtain wall as an example. This curtain wall is formed by alternately arranging a plate-shaped panel portion formed of an ALC plate or a steel plate and a vision portion formed of plate glass in the vertical direction (details are shown in the figure). omit). The arrangement of the panel portion and the vision portion on the outer wall 36 is arbitrary, and for example, all of them may be the vision portion of flat glass.

The outer wall 36 is an outer wall arranged on the above-ground part of the building 10. On the other hand, the outer wall of the underground portion of the building 10 is formed by the mountain retaining wall 40. In other words, the mountain retaining wall 40 also serves as the outer wall of the underground portion of the building 10.

In the following description, the beam 32, the slab 34, the outer wall 36, and other structures forming the outer peripheral portion 30 in the above-ground portion are collectively referred to as the above-ground skeleton 30A. Further, the beam 32, the slab 34, and other structures forming the outer peripheral portion 30 in the underground portion are collectively referred to as the underground skeleton 30B.

<How to build a building>
The construction method of the building 10 will be described with reference to FIGS. 2A to 5B.

(Excavation of the ground)
To construct the building 10, first, as shown in FIG. 2A, a mountain retaining wall 40 is formed on the ground G, and the ground G is excavated. In addition, a foundation deck 12 as a pressure plate is constructed on the root cutting bottom (excavation surface GA). The thickness of the foundation deck 12 is appropriately determined according to the groundwater pressure of the ground G and the like. The foundation floor slab 12 may be a mat slab or a floor slab combined with a foundation beam.

When excavating the ground G, a plurality of girders 42 are laid between the mountain retaining walls 40 facing each other. An abdomen (not shown) is appropriately arranged between the mountain retaining wall 40 and the girder 42 so that the reaction force from the girder 42 is not locally concentrated.

As shown in FIG. 2A, a plurality of cutting beams 42 are arranged in the vertical direction. Further, as shown in FIG. 2B, a plurality of cutting beams 42 are provided along the respective directions (X direction and Y direction) in which the sides of the mountain retaining wall 40 formed in a rectangular frame shape in a plan view face each other. Be placed.

The distance between the girders 42 is appropriately determined by the span of the retaining walls 40 facing each other, the excavation depth of the ground G, the water pressure, and the like.

(Standing of columnar body)
Next, as shown in FIGS. 3A and 3B, a plurality of columnar bodies 22A forming a part of the underground core portion 22 are erected above the foundation deck 12. The columnar body 22A is a wall column (in other words, a flat column formed in a rectangular wall shape) forming a part of the underground core portion 22. The columnar body 22A is formed of precast concrete and is fixed to the foundation deck 12 using anchor bolts or the like.

The columnar body 22A may be integrally formed by the length extending from the upper surface of the foundation deck 12 to the ground surface GL at the factory, or may be formed by dividing the columnar body 22A. When it is formed by dividing it, the divided members are joined to each other at the site for construction. Since the columnar body 22A is constructed prior to the underground skeleton 30B (see FIG. 1A), it cannot be fixed to the underground skeleton 30B. Therefore, it is preferable to appropriately use a wire support WS or the like in order to suppress the columnar body 22A from falling and to prevent it from falling.

As shown in FIG. 3B, the columnar bodies 22A are arranged apart from each other. Further, the columnar body 22A is arranged at a position where the underground core portion 22 shown by the broken line in FIG. 3B is formed. Further, the thickness d1 (thickness of the portion along the X direction) and d2 (thickness of the portion along the Y direction) of the columnar body 22A substantially coincide with the thickness of the underground core portion 22.

Further, the columnar body 22A is arranged between the cutting beams 42 adjacent to each other. In other words, the girder 42 is arranged so as to avoid the position of the columnar body 22A constructed after the girder 42 is installed. In other words, the girders 42 are arranged adjacent to each other and between the columnar bodies 22A forming the underground core portion 22.

(Construction of ground core part)
Next, as shown in FIGS. 4A and 4B, the stigmas of the columnar body 22A are connected to construct a wall-shaped above-ground core portion 24 above the columnar body 22A. The ground core portion 24 is constructed by the sliding foam method as an example. In the sliding foam method, the concrete skeleton is constructed sequentially from the bottom to the top while joining concrete to the formwork that can slide in the vertical direction. It is assumed that the above-ground core portion 24 is formed at least above the uppermost cutting beam 42.

In the ground core portion 24, reinforcing reinforcing bars (not shown) are arranged inside the portion to be constructed first, that is, the connecting portion 24A connecting the stigmas of the columnar body 22A. The reinforcing bars are arranged to support the load of the above-ground core portion 24. Further, the planar shape of the connecting portion 24A shown in FIG. 4B is substantially the same as the planar shape of the underground core portion 22 constructed later (see FIG. 3B).

As shown in FIG. 5A, a laminated portion 24B is constructed above the connecting portion 24A. The laminated portion 24B is formed by, for example, simultaneously placing concrete having a height of three layers of the building 10.

Further, while constructing the laminated portion 24B, that is, while constructing the above-ground core portion 24, the above-ground skeleton 30A is constructed around the above-ground core portion 24. The above-ground skeleton 30A includes at least one of the beam 32 and the slab 34 as described above. Further, the above-ground skeleton 30A may include other structures (for example, columns and partition walls).

It is preferable to use post-installed anchors for joining the above-ground core portion 24 to the beam 32 or the slab 34.

(Construction of underground skeleton)
As shown in FIG. 4A, the underground skeleton 30B is constructed around the columnar body 22A while constructing the above-ground core portion 24. The underground skeleton 30B includes at least one of the beam 32 and the slab 34 as described above. Further, the underground skeleton 30B may include other structures (for example, columns and partition walls 38).

Here, "while constructing the above-ground core portion 24" includes an embodiment of "while constructing the connecting portion 24A in the above-ground core portion 24". It also includes an embodiment of "after constructing the connecting portion 24A and before constructing the laminated portion 24B". Further, it includes an embodiment of "while constructing the laminated portion 24B after constructing the connecting portion 24A".

(Construction of underground core part)
Further, in parallel with the construction of the underground skeleton 30B, concrete is placed between the columnar bodies 22A adjacent to each other (casting portion 22B). Concrete will be poured sequentially from the bottom. That is, concrete is sequentially cast from the lower side between the columnar bodies 22A constituting the "part" of the underground core portion 22 to form the casting portion 22B which is the "other portion" of the underground core portion 22. .. As a result, the wall-shaped underground core portion 22 is sequentially constructed from the lower side.

(Removal of girder)
Further, the girder 42 is removed in parallel with the construction of the underground skeleton 30B and the formation of the driving portion 22B. By constructing the underground skeleton 30B and forming the driving portion 22B, the earth pressure acting on the mountain retaining wall 40 from the ground G is transferred from the girder 42 to the underground skeleton 30B and the underground core portion 22. .. Therefore, the deformation of the mountain retaining wall 40 due to the removal of the girder 42 can be suppressed.

To give an example of the method of forming the casting portion 22B, in the underground core portion 22, a portion other than the portion where the columnar body 22A is constructed is formed "at the same time". However, as shown in FIG. 5A, the heights formed at the same time are, for example, the heights of one to two layers of the building 10. In this case, the girder 42 is removed prior to the placement of the concrete forming the driving portion 22B.

Further, to give another example of the method of forming the casting portion 22B, in the underground core portion 22, a portion other than the portion in which the columnar body 22A is constructed is formed "sequentially". In this case, the cutting beam 42 is removed in a plurality of times, and the driving portion 22B is formed from the removed portion. For example, the cutting beam 42A shown in FIG. 3B is first removed to form a driving portion 22B in a portion through which the cutting beam 42A passes. Next, the cutting beam 42B is removed to form a driving portion 22B in the portion through which the cutting beam 42B passes.

In this way, the order of "construction of the underground skeleton 30B", "formation of the driving portion 22B" and "removal of the cutting beam 42" takes into consideration the earth pressure acting on the cutting beam 42 from the mountain retaining wall 40. It can be set as appropriate.

(Addition of columnar body)
As described above, in the method of constructing the building 10 according to the present embodiment, the underground skeleton 30B is constructed while constructing the above-ground core portion 24 (see FIGS. 4A and 5A). Then, in parallel with the construction of the underground skeleton 30B, the wall-shaped underground core portion 22 is sequentially constructed from the lower side (see FIG. 5A).

Here, as shown in FIG. 5B, as the construction of the above-ground core portion 24 progresses, the weights of the above-ground core portion 24 and the above-ground skeleton 30A increase, and the load acting on the columnar body 22A increases. However, as shown in FIG. 5A, there is a gap between the driving portion 22B and the connecting portion 24A during the period in which the underground core portion 22 is sequentially constructed from the lower side. When this gap is present, it is difficult for the driving portion 22B to support the load of the ground core portion 24. Therefore, the bearing capacity of the underground core portion 22 as a "pillar" that supports the weight of the above-ground core portion 24 and the above-ground skeleton 30A is unlikely to increase.

Therefore, in order to support this weight, a columnar body can be added while constructing the above-ground core portion 24. Specifically, as shown in FIG. 5B, the columnar bodies 22C are added between the columnar bodies 22A adjacent to each other from the upper surface of the foundation deck 12 to the lower surface of the connecting portion 24A in the ground core portion 24.

The columnar body 24C can be formed so as to fill the space between the columnar bodies 22A adjacent to each other as shown in this figure. In this case, a wall column in which the columnar body 24C and the columnar body 22A are integrated is formed. Alternatively, the columnar body 24C can be formed with a gap from the columnar body 22A adjacent to each other.

<Action>
In the building construction method according to the present embodiment, as shown in FIG. 3A, first, a plurality of columnar bodies 22A forming a part of the underground core portion 22 are erected above the foundation deck 12. Next, as shown in FIGS. 4A and 5A, the above-ground core portion 24 is constructed with the columnar body 22A as a support structure. Further, while constructing the above-ground core portion 24, the above-ground skeleton 30A, the other portion of the underground core portion 22 (casting portion 22B), and the underground skeleton 30B are constructed. That is, in the core structure building 10 having the basement floor, the above-ground skeleton 30A and the underground skeleton 30B can be constructed at the same time. Therefore, the construction period of the building 10 can be shortened as compared with the case where the above-ground skeleton 30A is sequentially constructed after the construction of the underground skeleton 30B.

Further, the columnar body 22A supporting the above-ground core portion 24 is a part of the underground core portion 22. That is, the columnar body 22A can be used as the main member. Therefore, the man-hours related to the removal can be reduced as compared with the case where the columnar body 22A is formed by the temporary member.

Further, the underground core portion 22 is constructed by separating the columnar body 22A and another portion (casting portion 22B). Therefore, the cutting beam 42 for holding the retaining wall 40 can be passed between the columnar bodies 22A until the driving portion 22B is constructed. As a result, it is possible to reduce the work such as replacement and replacement of the cutting beam 42. Further, the horizontal spacing of the cutting beams 42 can be narrowed as compared with the case where the cutting beams 42 are constructed while avoiding the entire underground core portion 22. Therefore, it is possible to reduce the reinforcement of the girder 42 and the abdomen.

Further, according to the building construction method according to the present embodiment, the columnar body 22A is formed of precast concrete. Therefore, the columnar body 22A can be started up more quickly than when it is formed of cast-in-place concrete. As a result, the construction period can be shortened.

Further, according to the building construction method according to the present embodiment, as shown in FIG. 5B, when the weight of the above-ground core portion 24 increases with the construction of the above-ground core portion 24, the columnar body 22C is added. As a result, the construction of the above-ground core portion 24 can be started at the stage where the number of columns is smaller than the number of columns finally required to support the weight of the above-ground core portion 24. That is, the construction of the above-ground core portion 24 can be started at an early stage. Therefore, the construction period can be shortened.

<Other Embodiments>
In the present embodiment, as shown in FIG. 3B, the columnar body 22A is a flat column formed in a rectangular wall shape. However, the embodiments of the present disclosure are not limited to this.

For example, the columnar body may have a substantially L-shape (in other words, a shape having a bent portion) to form a corner portion of the underground core portion 22, as in the columnar body 22D shown in FIG. 6A. Since the columnar body 22D formed in this way is easier to stand on its own than the columnar body 22A, the wire support can be simplified.

Further, in the present embodiment, the thickness d1 (thickness of the columnar body 22A along the X direction) and d2 (thickness of the columnar body 22A along the Y direction) of the columnar body 22A substantially coincide with the thickness of the underground core portion 22. There is. However, the embodiments of the present disclosure are not limited to this.

For example, the columnar body may be thinner than the thickness in the underground core portion 22 as in the columnar body 22E shown in FIG. 6B. As a result, the weight per columnar body is reduced, so that transportation and workability are improved.

Further, the columnar body may be formed of a steel frame material such as an H-shaped steel or a square steel pipe as in the columnar body 22F shown in FIG. 6C. By using the steel frame material, it is possible to easily join the connecting portion 24A in the foundation deck 12 and the ground core portion 24 by using anchor bolts, studs, and the like.

Furthermore, the columnar body may be formed using cast-in-place concrete. By using cast-in-place concrete, it is possible to reduce the transportation work from the factory and the lifting work with a crane.

Further, the building 10 to which the building construction method according to the present embodiment is applied is a center core type building, but the embodiment of the present disclosure is not limited to this. For example, the building 10 may be a building having cores at both ends and an eccentric core. The method described in the present disclosure can also be applied to the method for forming the core in this case.

Further, the outer wall of the underground portion of the building 10 is formed by the mountain retaining wall 40, but the embodiment of the present disclosure is not limited to this. For example, the outer wall of the underground portion of the building 10 may be constructed separately, and this outer wall may be arranged apart from the mountain retaining wall 40. In this case, it is preferable to reinforce the mountain retaining wall by using an earth anchor or the like.

Further, in the present embodiment, as shown in FIGS. 4A and 5B, the underground skeleton 30B is constructed in order from the floor closest to the foundation deck 12 (that is, from the lower floor to the upper floor). However, the embodiments of the present disclosure are not limited to this. For example, as shown in FIG. 7, a floor close to the ground (for example, the first basement floor) is constructed, and then a floor close to the foundation deck 12 (for example, the second basement floor shown by the alternate long and short dash line in FIG. 7) is constructed. May be good.

Further, as shown in FIG. 8 (A), the slab 34 on the first floor is constructed, and then the underground skeleton 30B (for example, the first basement floor and the second basement floor shown by the two-dot chain line in FIG. 8 (A)) is constructed. You may. The slab 34 on the first floor constructed prior to the underground skeleton 30B can be used as a work floor.

In the embodiment shown in FIG. 8A, a columnar body 50 as a gantry pile supporting the slab 34 is constructed before the slab 34 on the first floor is constructed. The columnar body 50 can be formed of a steel material such as H-shaped steel or a precast concrete column. Further, the columnar body 50 can be used as a main pillar. At this time, the columnar body 50 as the gantry pile may be used as it is as the main pillar, or may be covered with cast-in-place concrete.

Such a columnar body 50 is a case where a floor close to the ground (for example, the first basement floor) is constructed prior to the floor close to the foundation deck 12 (for example, the second basement floor) as in the embodiment shown in FIG. It can also be applied in.

Furthermore, although the building 10 is made of RC, the embodiment of the present disclosure is not limited to this. For example, the building 10 may be a steel-framed reinforced concrete structure or a steel-framed structure. As described above, the present disclosure can be implemented in various aspects.

The disclosure of Japanese Patent Application No. 2020-008308 filed on January 22, 2020 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

Claims

The process of building a foundation on the excavated surface of the excavated ground and
A step of erection of a plurality of columnar bodies forming a part of the underground core portion above the foundation, and
A step of connecting the stigmas of the columnar bodies to construct a wall-shaped above-ground core portion above the columnar bodies, and
While constructing the above-ground core portion, the process of constructing the above-ground skeleton around the above-ground core portion and
While constructing the above-ground core portion, an underground skeleton is constructed around the columnar body, and other portions of the underground core portion are sequentially constructed from the lower side to construct the wall-shaped underground core portion.
How to build a building with.
The columnar body is made of precast concrete and
The underground core portion is formed by placing concrete between the adjacent columnar bodies.
The method for constructing a building according to claim 1.
The columnar body is added while constructing the above-ground core portion.
The method for constructing a building according to claim 1 or 2.