JP6574336B2 - Steel-framed reinforced concrete columns and buildings using the same - Google Patents

Description

  The present invention is a building composed of an outer peripheral column disposed at a position to be an outer wall surface of a building, an outer peripheral beam constructed between the outer peripheral columns, and an inner beam constructed from the outer peripheral column toward the inside of the building. The present invention relates to a steel reinforced concrete structure (SRC structure) column used for the above, and a building using the same.

  In buildings such as office buildings, in order to make the internal space as large as possible, it is possible to construct seismic elements on the outer periphery of the building, reduce the number of pillars on the internal space side as much as possible, and build a frame with a large span is there.

  This type of structure is proposed in Patent Document 1. This reference 1 relates to an outer shell structure. In this outer shell structure, an outer peripheral column, an outer peripheral beam, and an inner beam are mainly used, an outer peripheral column is an SRC wall column, and both the outer peripheral beam and the inner beam are S structures. And In this case, the core steel frame and the outer peripheral beam are H-shaped steel, the inner beam is welded to the flange of the core steel frame, and the outer beam is not directly bonded to the core steel web structurally. The end is fixed to the concrete covering the outer peripheral column and rigidly joined. Then, the core steel webs are fastened with bolts and connected in the vertical direction so as to be integrally fixed to the covering concrete. In this way, the inner beam is made difficult to bend and the span of the inner beam is increased.

JP2013-245442A

However, the construction of this type of SRC building is usually carried out in the procedure of building a frame by joining column steel beams and beam steel frames at the construction site, and then placing concrete on the outer periphery of each steel frame. On the other hand, there are the following problems because the two processes of concrete work are performed separately.
(1) The construction period becomes longer compared to the construction by steel structure (S structure) and reinforced concrete structure (RC structure).
(2) There are two processes (steel frame building method, concrete work), and the construction becomes complicated.
(3) Since concrete is placed in a formwork in which steel frames and reinforcing bars are intricate, it is necessary to sufficiently perform construction management in order to fill the concrete without gaps.
In particular, in the above-described conventional outer shell structure, it is necessary to perform concrete work after the construction of the steel column in order to consolidate the steel column by fastening the upper and lower steel webs with bolts. There is a problem similar to a typical SRC structure.

  The present invention solves such a conventional problem, and aims to simplify the construction and shorten the construction period in this type of steel-framed reinforced concrete columns and buildings using the same. And

In order to achieve the above object, a steel reinforced concrete column according to the present invention includes:
(B) It consists of a plurality of divided pillar members,
(B) each pillar member is arranged steel columns in the axial direction to the core portion, a plurality of reinforcing bars in the axial direction around the steel column is reinforcement, the steel columns and the respective rebar Covered concrete is integrally cast, and is formed as a precast member having a flat cross-sectional substantially rectangular shape, and the ratio of the long side direction to the short side direction of the rectangular shape is about 1.5 to 5.5 times , Each of the reinforcing bars in the coated concrete is a cylinder whose upper or lower end protrudes from the upper or lower surface of the coated concrete by a predetermined length and has a predetermined length at the upper or lower end. Shaped mechanical rebar joint couplers are connected and embedded in the coated concrete, and the opening of each mechanical rebar joint coupler is opened on either the upper or lower surface of the coated concrete,
(C) The plurality of column members are vertically joined to each other without the steel column being directly joined between the column members, and the end portions of the reinforcing bars of one of the column members are the ones of the other column member. Inserted into a mechanical rebar joint coupler and joined, assembled by a precast method,
This is the gist.

Pillar of the steel reinforced concrete are also Ru includes the following configuration in each section.
( 1 ) Each column member is formed so that the steel column can be divided at the center of the floor.
(2) Each column member end plate is attached to the upper and lower ends of the steel columns, the previous SL end plates to each other between the respective pillar members are connected via the reinforcing bars.
In this case, the end plate extends in the horizontal direction on both sides of the steel column at the upper and lower ends of the steel column, and holes for penetrating reinforcing bars are drilled on both sides, so that the above-described one of the upper and lower ends of each steel column Reinforcing bars of a predetermined length are vertically attached to the holes for penetrating the reinforcing bars on both sides of the end plate, and are attached to the inner side surfaces on both sides of the end plate at either the upper or lower end of each steel column. A mechanical rebar joint coupler having a predetermined length through which the rebar of the end plate at either one of the upper and lower ends can be inserted is communicated with a hole for rebar penetration, and between the column members. It is preferable that the rebar is inserted into the mechanical rebar joint coupler to connect the end plates between the column members.
( 3 ) In each column member, a beam main bar or a precast beam protrudes from the steel column toward the outer periphery of the building at approximately the center in the height direction.
( 4 ) Each column member has a steel beam projecting from the steel column toward the interior of the building at approximately the center in the height direction.

In order to achieve the above object, the present invention provides a building in which an outer peripheral column is disposed at a position to be an outer wall surface of a building, and an outer peripheral beam is installed between the outer peripheral walls. The main point is that steel reinforced concrete columns are used.
In this case, the outer peripheral beam is preferably a reinforced concrete beam.
In this case, it is preferable that the internal beam erected from the outer peripheral column toward the inside of the building is a steel beam.

The steel reinforced concrete column according to the present invention and a building using the column have the following special effects due to the above configuration.
(1) A steel column is arranged in a core portion with a plurality of column members facing the axial direction, a plurality of reinforcing bars are arranged around the steel column in the axial direction, and the concrete is coated on the steel column and each reinforcing bar. It is cast as a single piece and formed as a precast member with a flat cross-section having a substantially rectangular shape, and the ratio of the long side direction to the short side direction of the rectangular shape is about 1.5 to 5.5 times. In addition, without directly joining the steel columns between the column members, the end of each reinforcing bar of one column member is inserted into the coupler for mechanical rebar joint of the other column member and joined. It enables the precasting of steel reinforced concrete columns.
(2) Employing the precast method enables labor and labor saving in construction.
(3) A steel column is arranged in the axial direction in the core part with a plurality of column members, a plurality of reinforcing bars are arranged in the axial direction around the steel column, and the concrete is coated on the steel column and each reinforcing bar. It is cast as a single piece and formed as a precast member with a flat cross-section having a substantially rectangular shape, and the ratio of the long side direction to the short side direction of the rectangular shape is about 1.5 to 5.5 times. In addition, without directly joining the steel columns between the column members, the end of each reinforcing bar of one column member is inserted into the coupler for mechanical rebar joint of the other column member and joined. The bending moment can be transmitted through the reinforcing bars at the joints between the steel columns of the respective column members, and even when there are no inflection points at the joints, sufficient proof stress and deformation performance are provided.
(4) Since the bending moment can be transmitted at the joint of the steel column of each column member, a bending reinforcing bar for securing the structural performance between the joints of each column member is unnecessary.
As described above, according to the steel-framed reinforced concrete column of the present invention and the building using the same, the construction can be simplified and the construction period can be shortened.

The perspective view which shows the structure of the column of the steel reinforced concrete structure in one embodiment of this invention The figure which shows the structure of the steel column especially the same column ((a) is a side view (b) is an end view) Side view showing the joint structure of steel columns, especially steel columns The figure which shows the internal structure of the pillar ((a) is a perspective view which shows the state before the covering concrete placement of the pillar, (b) is the perspective view which shows the state after the covering concrete placement of the pillar) Perspective view showing the external structure of the pillar The figure which shows the flow of the force in the junction part between the steel column of each column member of the same column Diagram showing the action of the pillar Perspective view showing a building using the same pillar The figure which shows the modification of the same pillar

Next, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 shows a steel reinforced concrete column. In addition, this pillar is illustrated as what comprises the outer periphery pillar (wall pillar) arrange | positioned in the position of the outer peripheral surface of a building.
As shown in FIG. 1, the steel-framed reinforced concrete column P is composed of a plurality of divided column members P1. Each of these column members P1 has a steel column 1 arranged in the axial direction in the core portion, and a plurality of reinforcing bars 2 are arranged around the steel column 1 in the axial direction. 2 is formed as a precast (steel reinforced concrete) member in which the covering concrete 3 is integrally cast, and each reinforcing bar 2 in the covering concrete 3 is either one of the upper and lower ends, in this case, the upper end 21 is the covering concrete 3. One of the upper and lower surfaces in this case, in this case, a cylindrical mechanical rebar joint projecting from the upper surface by a predetermined length and having the predetermined length at either the upper or lower end, in this case, the lower end 22 The coupler 23 is connected and embedded in the coated concrete 3, and the opening 230 of each mechanical rebar joint coupler 23 is opened on either the upper or lower surface of the coated concrete 3, in this case, the lower surface.
Moreover, each pillar member P1 is formed in the flat cross-section substantially rectangular shape, and the ratio of the said rectangular long side direction and short side direction is about 1.5 to 5.5 times. The steel column 1 of each column member P1 is formed so that it can be divided substantially at the center of the floor height, end plates 4 are attached to the upper and lower ends of the steel column 1, respectively, and the steel column 1 is approximately at the center in the height direction of each column member P1. A beam main reinforcing bar 5 projects from 1 toward the outer periphery of the building, and a beam steel frame 6 projects from the steel column 1 toward the interior of the building.

As shown in FIG. 2, the steel column 1 is formed to have a predetermined length by H-shaped steel according to the floor height of the building, and as shown in FIG. It is divided at the position.
As shown in FIGS. 2 and 3, end plates 4 made of steel are attached to the upper and lower ends of the steel column 1 by welding or the like. This end plate 4 has a substantially rectangular flat plate shape, one side having a length substantially the same as the inner length between the flanges 11 and the other side having a length obtained by removing the thickness of the web 12 from the width of the flange 11. It is formed to be approximately the same as 1/2 or slightly longer, and is extended horizontally on both sides (of the web 12) of the steel column 1 at the upper and lower ends of the steel column 1. In addition, this end plate 4 is only an example, and if it has the same function as the end plate, for example, as shown in FIG. 2C, one side is the same as the length of the flange, and the other side. A rectangular steel plate having the same length as that of the web (including the thickness of the flange) may be used. A plurality of holes 40 for penetrating reinforcing bars are formed in portions of the end plate 4 extending on both sides of the steel column 1, and the end plate 4 at the upper or lower end of the steel column 1, in this case, the upper end portion 4. Reinforcing bars 41 of a predetermined length are vertically attached to the holes 40 for penetrating reinforcing bars on both sides of the steel frame 1, and either the upper or lower end of the steel column 1, in this case, on both sides of the end plate 4 at the lower end. A mechanical rebar coupling coupler 42 having a predetermined length through which the reinforcing bars 41 of the end plate 4 at the upper end can be inserted is attached to the inner surface, in this case, the upper surface, to the hole 40 for penetrating the reinforcing bars. In this case, the reinforcing bar 41 attached to the end plate 4 at the upper end portion of the steel column 1 protrudes above the end plate 4 in the vicinity of the upper half of the entire length, and is arranged around the steel column 1. The height of each reinforcing bar 2 is substantially the same as the upper end portion, and a portion near the lower half of the reinforcing bar 2 is disposed below the end plate 4. The mechanical rebar joint coupler 42 is substantially the same as or slightly longer than the length of the rebar 41 protruding from above the end plate 4 at the upper end of the steel column 1.
Further, as shown in FIG. 4 (a), the beam main bar 5 is attached at a substantially right angle to the H-shaped steel web 12 at the center of the steel column 1 in the height direction. The beam steel frame 6 is attached at a substantially right angle to the flange 11. In this case, the beam main reinforcing bars 5 are inserted and arranged in holes (not shown) provided in the web 12 of the column steel frame 1. Note that the beam main reinforcement 5 is not fixed to the column steel frame 1. In some cases, the main beam 5 may not be penetrated through the column steel frame 1 and may be mechanically fixed and bent and fixed before the column steel frame 1. In this attachment, the beam main bars 5 protruding from both sides of the column member (precast member) P1 (both sides of the web 12 of the column steel frame 1) are not connected. In this case, the beam steel frame 6 is joined to the flange 11 of the column steel frame 1 by welding.
The steel column 1 has such a configuration, and as shown in FIG. 4, both sides of the H-shaped steel web 12 are arranged in the width direction center of the column member P1 in the covering concrete 3 so as to face the width direction of the column member P1. A portion (substantially lower half) of the reinforcing bar 41 attached to the end plate 4 at the upper end of the steel column 1 and a mechanical reinforcing bar attached to the end plate 4 at the lower end of the steel column 1 The upper portion (substantially upper half) of the reinforcing bar 41 fixed to the covering concrete 3 together with the coupling coupler 42 (see FIGS. 2 and 3) and attached to the end plate 4 at the upper end of the steel column 1 is substantially upper half. It protrudes from the upper surface of the covering concrete 3.

As shown in FIG. 4, each of the plurality of reinforcing bars 2 includes the length of the steel reinforcing column 1 by the amount that each reinforcing bar 2 protrudes from the upper surface of the covering concrete 3, including the length of the mechanical reinforcing bar joint coupler 23 at the lower end. It is formed longer than this. These reinforcing bars 2 are arranged in parallel at predetermined intervals on both sides of the steel column 1, and a plurality of frame-shaped shear reinforcing bars 24 are arranged at predetermined intervals in the vertical direction in a horizontal state around the reinforcing bars 2. The
The plurality of reinforcing bars 2 have such a configuration, and are arranged on both sides of the steel column 1 in the covering concrete 3, and are assembled to the covering concrete 3 by being assembled into a substantially flat column shape around the steel column 1 together with the shear reinforcing bars 24. The upper end 21 of each reinforcing bar 2 is projected from the upper surface of the coated concrete 3 by a predetermined length, and the lower end opening 230 of the mechanical reinforcing bar joint coupler 23 at the lower end of each reinforcing bar 2 is opened on the lower surface of the coated concrete 3. The

As shown in FIG. 4B and FIG. 5, the covering concrete 3 is cast integrally with the steel frame 1 and the plurality of reinforcing bars 2, and as a whole is substantially the same height as the steel column 1 and is vertically long and has a thickness dimension. Is formed in a substantially rectangular parallelepiped column shape having a large width dimension, and has a flat, substantially rectangular cross section. The ratio of the long side direction to the short side direction of this cross section is 2.5 to 5.5 times as described above.
The covering concrete 3 has such a configuration, and as described above, the upper end portions 21 of the plurality of reinforcing bars 2 protrude from the upper surface of the covering concrete 3, and the beam main reinforcing bars 5 protrude from the vertical center of both side surfaces of the covering concrete 3. The beam steel frame 6 protrudes from the center of one large surface of the covering concrete 3.

  Thus, the column member P1 is configured, and as shown in FIG. 1, the plurality of column members P1 are vertically moved, and the steel column 1 is not directly joined between the column members P1, and the lower one column is formed. The upper end portion 21 of each reinforcing bar 2 of the member P1 is inserted into the mechanical reinforcing bar joint coupler 23 of the other upper column member P1, and each reinforcing bar 41 protruding from the end plate 4 of the lower one column member P1 is provided. It is inserted into each mechanical rebar joint coupler 42 through the end plate 4 of the other upper pillar member P1 (see FIG. 3), and the grout material 7 (see FIG. 3) such as mortar is filled in each coupler 23, 42. And assembled by the precast method. The beam reinforcement 5 protruding from both side surfaces of each column member P1 is provided with a reinforced concrete (RC) beam, and the beam steel frame 6 protruding from the center of one large surface of each column member P1 Steel frame (S) beams are provided.

In addition, due to the joining structure of the pillar members P1, the bending moment generated by the external force on each pillar member P1 is transmitted by the reinforcing bars 2 and 41 between the joining portions of the pillar members P1.
FIG. 6 shows the flow of force at the joint between the steel pillars 1 of each pillar member P1. As shown in FIG. 6, when a bending moment is generated in each column member P <b> 1, this is transmitted from each rebar 2, 41 to the end plate 4 through the covering concrete 3, and from the end plate 4 to the H-shaped steel flange 11. A bending moment can be transmitted between the joints of the column members P1. As described above, since the bending moment can be transmitted between the joints of the column members P1 as shown in FIG. 7, the inflection point may or may not be at the center of the joint between the steel columns 1 or not. Sufficient proof stress and deformation performance can be obtained for each steel column 1. Further, since the bending moment can be transmitted between the joint portions of the column members P1 as described above, a bending reinforcing bar for securing the structural performance of the joint portion is not necessary.

As described above, in the column P of this SRC, a plurality of divided column members P1 are vertically moved, and the steel column 1 is not directly joined between the respective column members P1, so that the lower one column member P1 is formed. By inserting the upper end portions of the reinforcing bars 2 and 41 into the mechanical reinforcing bar joint couplers 23 and 42 of the upper column member P1 and joining them, it is possible to precast the steel reinforced concrete column P. . And since this pillar P is constructed by a precast construction method, labor saving and labor saving of construction of a steel reinforced concrete pillar can be achieved. Further, since the bending moment can be transmitted through the reinforcing bars 2 and 41 at the joint portion of the steel column 1 of each column member P1, even when the inflection point is not present at the joint portion, sufficient strength and deformation performance are provided. The bending reinforcement for securing the structural performance between the joint portions of each column member P1 can be eliminated.
Therefore, according to this steel reinforced concrete column P, the construction of the outer peripheral column (wall column) arranged at the position of the outer peripheral surface of the building can be simplified, and the construction period can be shortened.

FIG. 8 illustrates a building B using the pillar P of the SRC.
As shown in FIG. 8, in this building B, an outer peripheral column B1 is disposed at a position to be an outer wall surface, an outer peripheral beam B2 is installed between the outer peripheral columns B1, and the seismic element that bears the seismic force is the building B. Located in the outer periphery, the inside of the building B has a large span to secure a large space, and the inner column B1 extends from the outer column B1 toward the inside of the building B (in other words, sandwiches the inside of the building B) The internal beam B3 is installed between the outer peripheral columns B1 facing each other.

  The SRC column P described above is adopted as the outer peripheral column B1 of the building B, the outer peripheral beam B2 is a reinforced concrete beam (RC beam), and the inner beam B3 is a steel beam (S beam). It is as.

In this building B, as described above, the steel-framed reinforced concrete columns P of the outer peripheral columns B1 can be moved downward without directly joining the steel columns 1 between the column members P1 up and down the plurality of column members P1. The upper ends of the rebars 2 and 41 of the one side column member P1 are precast by inserting and joining the mechanical rebar joint couplers 23 and 42 of the upper side column member P1 and formed by a precast method. In addition, by adopting the precast construction method, labor and labor can be saved. Further, from the structure of the steel reinforced concrete column P, the bending moment can be transmitted through the reinforcing bars 2 and 41 at the joint portion of the steel column 1 of each pillar member P1, and even when the inflection point is not in the joint portion. , Sufficient proof stress and deformation performance can be given. Furthermore, since the bending moment can be transmitted at the joints of the steel columns 1 of the column members P1, bending reinforcement bars for securing the structural performance between the joints of the column members P1 become unnecessary.
Therefore, by using the steel-framed reinforced concrete column P for the outer peripheral column B1 of this type of building B, the construction of the steel-framed reinforced concrete column can be simplified and the construction period can be shortened.

In each of the above-described embodiments, the reinforced concrete (RC) beam is provided on the beam main bar 5 protruding from both side surfaces of each column member P1, but the beam main bar is shown in FIG. In this way, a precast member (precast beam) having a length approximately up to the center of the span may be attached.
Further, in each of the above embodiments, each reinforcing bar 2 in the covering concrete 3 has a cylindrical shape with an upper end protruding from the upper surface of the covering concrete 3 by a predetermined length and a lower end having a predetermined length. The reinforced joint coupler 23 is connected and embedded in the coated concrete 3, and the opening 230 of each mechanical reinforced joint coupler 23 is opened on the lower surface of the coated concrete. Each reinforcing bar has a lower end protruding from the lower surface of the coated concrete by a predetermined length, and a cylindrical-shaped mechanical rebar coupler coupler having a predetermined length is connected to the upper end to be embedded in the coated concrete. The opening of each mechanical rebar joint coupler is opened on the upper surface of the coated concrete, the plurality of column members are vertically and the end of each rebar of one column member is the mechanical rebar joint of the other column member. Or as being joined are inserted into Couplers.
Similarly, in each of the above-described embodiments, a reinforcing bar 41 having a predetermined length is vertically attached to and attached to the reinforcing bar penetration holes 40 on both sides of the end plate 4 at the upper end of each steel column 1. 1 is connected to a hole 40 for reinforcing bar penetration on the upper surface of both ends of the end plate 4 at the lower end of the first end, and has a predetermined length through which each reinforcing bar 41 of the end plate 4 at the upper end can be inserted. 42 is attached, and the reinforcing bar 41 is inserted into the mechanical rebar coupling coupler 42 between the column members P1 and the end plates 4 between the column members P1 are connected. Reinforcing bars penetrated on the bottom of both ends of the end plate at the upper end of each steel column, and a reinforcing bar of a predetermined length is attached to the holes for rebar penetration on both sides of the end plate at the lower end of each steel column. The lower end of the end play A coupler for mechanical rebar joints with a predetermined length that can be inserted through each rebar is attached, and the rebar is inserted into the mechanical rebar joint coupler between each column member to connect each end plate between each column member It is good also as what is done.
Further, in each of the above-described embodiments, the steel-framed reinforced concrete column P is provided with an outer peripheral column at a position to be an outer wall surface, and an outer peripheral beam is installed between the outer peripheral columns, so that the seismic element that bears seismic force is a building It was illustrated as being applied to a building in which the inside of the building has a large span in order to secure a large space, and the inner beam extends from the outer column to the inside of the building B. Needless to say, the reinforced concrete column P can be used in place of a steel-framed reinforced concrete column cast in a general building.

P Steel column reinforced concrete column P1 Column member 1 Steel column 11 Flange 12 Web 2 Reinforcement 21 Upper end 22 Lower end 23 Cylindrical mechanical coupler coupler 230 Opening 24 Shear reinforcement 3 Covered concrete 4 End plate 40 Hole 41 Reinforcement 42 Cylindrical mechanical joint coupler 5 Beam main reinforcement 6 Beam steel 7 Grout material B Building B1 Outer column B2 Outer beam B3 Inner beam

Claims (9)

It consists of multiple divided pillar members,
Each pillar member is arranged steel columns in the axial direction to the core portion, a plurality of reinforcing bars in the axial direction around the steel column is reinforcement, coated concrete to the steel columns and the respective rebar Are integrally formed and formed as a precast member having a flat rectangular cross section and a ratio of the long side direction to the short side direction of the rectangular shape of about 1.5 to 5.5 times . Each of the reinforcing bars has a cylindrical shape in which either one of the upper and lower ends protrudes from the upper or lower surface of the coated concrete by a predetermined length, and the upper or lower end has a predetermined length. Mechanical rebar couplers are connected and embedded in the coated concrete, and the opening of each mechanical rebar coupler coupler is opened on either the upper or lower surface of the coated concrete,
The plurality of column members are vertically joined, and the steel column is not directly joined between the column members, and the end of each reinforcing bar of one of the column members is the mechanical reinforcing bar of the other column member. Inserted into a coupler for coupling and joined, assembled by a precast method,
A steel-framed reinforced concrete column. The steel column reinforced concrete column according to claim 1, wherein each column member is formed so that a steel column can be divided substantially at the center of the floor . Each column member is a steel reinforced concrete column according to claim 1 or 2 , wherein end plates are attached to upper and lower ends of the steel column, and the end plates are connected between the column members via reinforcing bars . End plates extend horizontally on both sides of the steel columns at the upper and lower ends of the steel columns, and holes for penetrating reinforcing bars are drilled on both sides, so that the end plates of the upper and lower ends of each steel column A reinforcing bar having a predetermined length is vertically attached to the holes for penetrating the reinforcing bars on both sides, and the reinforcing bars are penetrated on the inner side surfaces on both sides of the end plate at the other end of each steel column. A mechanical rebar coupling coupler having a predetermined length through which the reinforcing bars of the end plate at either one of the upper and lower ends can be inserted, and the reinforcing bars are connected between the column members. The steel reinforced concrete column according to claim 3, wherein said end plate is connected to said column member by being inserted into said coupler for mechanical rebar joint . Each pillar member Steel reinforced concrete pillars according to any of claims 1 to 4 in which the beam main reinforcement or precast beam toward the outer circumferential direction of the building in the height direction approximately steel columns in the center is projected. The steel reinforced concrete column according to any one of claims 1 to 5, wherein each column member has a steel beam projecting from the steel column toward the inside of the building at substantially the center in the height direction . An outer peripheral column is disposed at a position to be an outer wall surface of the building, and an outer peripheral beam is constructed between the outer peripheral walls,
The steel reinforced concrete column according to any one of claims 1 to 6 is adopted as the outer peripheral column.
A building characterized by that . The building according to claim 7, wherein the outer circumferential beam is a reinforced concrete beam . The building according to claim 7 or 8, wherein the internal beam constructed from the outer peripheral column toward the inside of the building is a steel beam .

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