Building structure

Abstract

To provide a structure of a building capable of effectively supporting a steel column by an existing column even when the center of the lower end of the steel column of a new building is shifted in the horizontal direction to the axis of the internal steel of the existing column.SOLUTION: A building structure 1 includes an existing column 10 made of reinforced steel-framed concrete and constituting a basement skeleton 2, a steel column 20 in which a center of a lower-end side 20a is horizontally shifted with respect to a central axis line O1 of an internal steel-framed side 10a of the existing column 10, an intermediate steel frame 30 having a shape obliquely expanding from an upper-end side 30a toward the lower-end side 30b and connected to the lower-end side 30a of the steel column 20 at the upper-end side 20a and having a part of the lower-end side 30b disposed on the internal steel-framed side 10a, and a covering concrete portion 40 covering the existing column 10 and the intermediate steel frame 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a building structure that reuses the underground structure and foundation structure of an existing building. [Background technology]

[0002] For example, when constructing a new building such as an office building, hotel, or apartment building, it has been proposed to reuse the underground structure and foundation structure of an existing building and construct the new building on top of it, thereby shortening the construction period and reducing costs associated with constructing the new building (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-142687 Summary of the Invention [Problem to be solved by the invention]

[0004] When constructing a new building on top of the underground structure of an existing building, it is possible to connect the steel columns of the new building to the existing columns of the SRC (reinforced concrete) structure that makes up the underground structure of the existing building.

[0005] However, if the span of the steel columns of the new building differs from the span of the existing columns of the existing building, the center of the lower end of the steel columns of the new building will be horizontally shifted from the axis of the internal steel frame of the existing SRC columns, making it difficult to configure the existing columns to effectively support the steel columns.

[0006] The present invention was made in consideration of such problems, and its purpose is to provide a building structure that can effectively support a steel column with an existing column even if the center of the lower end of the steel column of a newly constructed building is horizontally offset from the axis of the internal steel frame of the existing column. [Means for solving the problem]

[0007] The building structure of the present invention is characterized by comprising existing columns made of reinforced concrete that constitute the underground structure; steel columns whose lower end centers are horizontally offset from the central axis of the internal steel frame of the existing columns; intermediate steel frames whose diameters expand diagonally from their upper ends to their lower ends, whose upper ends are connected to the lower ends of the steel columns and whose lower ends are partially positioned on top of the internal steel frame; and a covering concrete portion that covers the existing columns and the intermediate steel frame.

[0008] In the building structure of the present invention, in the above configuration, it is preferable that a part of the steel column including its lower end is covered by the covering concrete portion. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a building structure in which a steel column can be effectively supported by an existing column even if the center of the lower end of the steel column of a newly constructed building is horizontally offset from the axis of the internal steel frame of the existing column. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a main part of a building structure according to one embodiment of the present invention, as viewed from the front. [Figure 2] FIG. 2 is a cross-sectional side view of a main part of the structure of the building shown in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a building structure according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0012] The building structure 1 according to one embodiment of the present invention shown in Figures 1 and 2 reuses the underground structure 2 and foundation structure (not shown) of an already constructed building, i.e., an existing building, to form part of a building 3 in which the above-ground portion is constructed on top of the underground structure 2.

[0013] The building structure 1 has an existing column 10, a steel column 20, an intermediate steel frame 30, and a covering concrete portion 40.

[0014] The existing column 10 constitutes part of the underground structure 2. The underground structure 2 is constructed underground together with a foundation structure (not shown), and the existing column 10 is installed underground with its lower end supported by the foundation structure. The existing column 10, together with the foundation structure and the underground structure 2, is made of reinforced steel concrete and includes an inner steel frame 10a, a concrete portion 10b covering the inner steel frame 10a, and multiple reinforcing bars 10c arranged inside the concrete portion 10b. The inner steel frame 10a is formed from a straight cross-shaped steel beam and is arranged vertically so that its central axis O1 is aligned vertically. The concrete portion 10b has a rectangular horizontal cross section and completely covers the periphery of the inner steel frame 10a. The upper end 10d of the inner steel frame 10a is flush with the upper end of the concrete portion 10b and is not covered by the concrete portion 10b. The reinforcing bar 10c extends straight in the vertical direction outside the inner steel frame 10a, and part of its upper end protrudes upward from the upper end of the concrete portion 10b. For convenience, only one reinforcing bar 10c is shown in Fig. 1 and only two reinforcing bars 10c are shown in Fig. 2, but multiple reinforcing bars other than the illustrated reinforcing bar 10c are arranged in an appropriate direction or position in the concrete portion 10b.

[0015] The internal steel frame 10a of the existing column 10 is not limited to being formed of a straight cross-section steel, but may be formed of steel frames of other shapes, such as H-shaped steel. Furthermore, the concrete portion 10b of the existing column 10 is not limited to being formed of a rectangular horizontal cross section, but may be formed of other horizontal cross-sectional shapes as long as it covers the entire periphery of the internal steel frame 10a.

[0016] The underground structure 2 may have a plurality of existing columns (not shown) other than the existing column 10 shown in Figures 1 and 2, and may also have an existing beam 11 (see Figure 2) connected to the existing column 10 and a plurality of existing beams connected to a plurality of existing columns (not shown) other than the existing column 10. Furthermore, when reusing the underground structure 2, the building structure 1 may have a configuration in which a plurality of newly installed beams 12 are connected to the existing column 10 or a plurality of existing columns other than the existing column 10.

[0017] The steel column 20 constitutes the upper part of the building 3. The steel column 20 is disposed above the existing column 10 so that its lower end 20a is located above the upper end 10d of the internal steel frame 10a of the existing column 10.

[0018] In this embodiment, the steel column 20 has a column main body 21 and a joint 22. The column main body 21 is formed of a square steel pipe and is inclined with respect to the vertical direction in the front view shown in Fig. 1, and is inclined with respect to the vertical direction at an angle smaller than the angle in the front view in the side view shown in Fig. 2. The joint 22 is formed of a square steel pipe having a truncated square tubular shape whose diameter decreases downward, and is connected to the lower end of the column main body 21 via a diaphragm 23 by welding or the like. The steel column 20 may be configured such that the interior of the column main body 21 and the interior of the joint 22 are filled with concrete 24.

[0019] The building structure 1 may have a configuration in which a plurality of new beams 25 are connected to the joint portion 22.

[0020] The steel column 20 is not limited to a configuration having a column body 21 and a joint 22, and may be configured without the joint 22. Furthermore, the steel column 20 is not limited to one formed from a square steel pipe, and may be one formed from steel of other shapes, such as H-shaped steel.

[0021] The steel column 20 is arranged with respect to the existing column 10 such that the center 20b of the lower end 20a is horizontally offset from the central axis O1 of the internal steel frame 10a of the existing column 10. In this embodiment, the steel column 20 is arranged so that the center 20b of the lower end 20a is horizontally offset from the central axis O1 of the existing column 10 in the front view shown in FIG. 1, and so that the center 20b of the lower end 20a coincides with the central axis O1 of the existing column 10 in the side view shown in FIG. 2. Furthermore, in this embodiment, the steel column 20 is arranged so that the lower end 20a does not overlap the existing column 10 in a plan view. In other words, there is a horizontal gap between the lower end 20a and the existing column 10.

[0022] The intermediate steel frame 30 has a shape that expands diagonally from the upper end 30a to the lower end 30b, and is connected to the lower end 20a of the steel column 20 at the upper end 30a, with a portion of the lower end 30b being placed on top of the internal steel frame 10a of the existing column 10.

[0023] In this embodiment, as shown in FIG. 3, the intermediate steel frame 30 has four side walls 30c, 30d, 30e, and 30f, and has a rectangular cylindrical shape whose diameter increases obliquely from the upper end 30a to the lower end 30b. More specifically, as shown in FIG. 1, the intermediate steel frame 30 has a side wall 30c facing away from the existing column 10 that is parallel to the vertical direction, and a side wall 30d facing the existing column 10 that is inclined relative to the vertical direction, so that when viewed from a horizontal direction (the direction of the paper in FIG. 1) that is perpendicular to the direction in which the center 20b of the lower end 20a of the steel column 20 shifts horizontally relative to the central axis O1 of the internal steel frame 10a of the existing column 10, the horizontal width of the lower end 30b is wider than the horizontal width of the upper end 30a, and the central axis O2 connecting the horizontal center position of the upper end 30a and the horizontal center position of the lower end 30b is inclined, so that the diameter of the intermediate steel frame 30 increases obliquely from the upper end 30a to the lower end 30b. 2, the intermediate steel frame 30 has side walls 30e, 30f on both sides between the side walls 30c and 30d that are inclined so that the distance between them gradually narrows from the upper end 30a to the lower end 30b, so that when viewed from a direction in which the center 20b of the lower end 20a of the steel column 20 is horizontally shifted relative to the central axis O1 of the internal steel frame 10a of the existing column 10, the horizontal width of the lower end 30b is narrower than the horizontal width of the upper end 30a, and the central axis O2 extends vertically along the central axis O1 of the internal steel frame 10a of the existing column 10. The upper end 30a of the intermediate steel frame 30 has the same shape as the lower end 20a of the steel column 20, and is connected to the lower end 20a of the steel column 20 via a diaphragm 31 by welding or the like. On the other hand, a portion of the lower end 30b of the intermediate steel frame 30 on the side of the side wall 30d is placed on top of the internal steel frame 10a of the existing column 10 via the diaphragm 32 joined to the lower end 30b and a portion of the covering concrete portion 40. The remaining portion of the lower end 30b of the intermediate steel frame 30 is placed offset from the internal steel frame 10a of the existing beam 10.

[0024] The intermediate steel frame 30 preferably has a configuration in which a plurality of studs 34 are fixed to its outer surface to be engaged with the covering concrete portion 40. For convenience, reference numerals are given to only some of the studs 34 in Figs. 1 to 3. The intermediate steel frame 30 may also be configured so that concrete 35 is filled inside.

[0025] The covering concrete portion 40 covers the existing column 10 and the intermediate steel frame 30. This forms a new column 50 made of reinforced steel concrete, in which the internal steel frame 10, intermediate steel frame 30, and reinforcing bars 33 of the existing column 10 are embedded in the covering concrete portion 40. The reinforcing bars 33 are connected to the upper ends of the reinforcing bars 10c protruding from the existing column 10. For convenience, only one reinforcing bar 33 is shown in FIG. 1 and only two reinforcing bars 33 are shown in FIG. 2, but multiple reinforcing bars other than the reinforcing bars 33 shown in the drawings are arranged in the covering concrete portion 40.

[0026] In this embodiment, the covering concrete portion 40 covers not only the existing column 10 and the intermediate steel frame 30, but also a portion of the steel column 20 including the lower end 20a (a portion of the lower end side of the column main body portion 21 and the entire joint portion 22).

[0027] In this embodiment, the covering concrete portion 40 is composed of a lower portion 41 that covers the existing column 10 and an upper portion 42 that covers a portion of the existing column 10, including the intermediate steel frame 30 and the lower end 20a of the steel column 20. More specifically, the lower portion 41 of the covering concrete portion 40 covers only the side surface 10e of the existing column 10 facing the lower end 20a of the steel column 20, and the concrete portion 10b of the existing column 10 and the lower portion 41 of the covering concrete portion 40 form the lower outer surface of the new column 50, which has a rectangular horizontal cross section. In addition, a trapezoidal protrusion 43 that protrudes upward is integrally provided on the lower portion 41 of the covering concrete portion 40, and a diaphragm 32 joined to the lower end 30b of the intermediate steel frame 30 is partially placed on the inner steel frame 10a via the protrusion 43, and the remaining portion is placed on the lower portion 41 via the protrusion 43. On the other hand, the upper portion 42 of the covering concrete portion 40 has the same horizontal cross-sectional shape as the lower portion 41, and covers the entire periphery of the intermediate steel frame 30 and a portion of the steel column 20, including the lower end 20a, to form the upper outer surface of the new column 50. The covering concrete portion 40 configured in this way can be constructed by pouring concrete to cover the existing column 10 to form the lower portion 41 and the protruding portion 43, then installing the intermediate steel frame 30, the steel column 10, and the new beam 25, and then pouring concrete on the lower portion 41 to form the upper portion 42.

[0028] The upper portion 42 may be integrally formed with a covering portion 44 that covers one of the new beams 12, and the lower portion 41 may be integrally formed with a covering portion 45 that covers one of the new beams 25.

[0029] According to the building structure 1 of this embodiment having the above-mentioned configuration, an intermediate steel frame 30 having a shape that expands obliquely from the upper end 30a to the lower end 30b is placed between the existing column 10 of reinforced steel concrete construction that constitutes the underground skeleton 2 and the steel column 20 whose center 20b of the lower end 20a is horizontally shifted with respect to the central axis O1 of the internal steel frame 10a of the existing column 10, and the intermediate steel frame 30 is connected to the lower end 20a of the steel column 20 at the upper end 30a and has a part of the lower end 30b placed on the internal steel frame 10a of the existing column 10. In both cases, the existing column 10 and the intermediate steel frame 30 are covered with the covering concrete portion 40, so that even if there is a large horizontal deviation of the center 20b of the lower end 20a of the steel column 20 relative to the central axis O1 of the internal steel frame 10a of the existing column 10, the load of the steel column 20 is transmitted to the internal steel frame 10a of the existing column 10 and the lower portion 41 of the covering concrete portion 40 via the intermediate steel frame 30, which has a shape that expands diagonally, so that the steel column 20 of the building 3 can be effectively supported by the underground structure 2.

[0030] In addition, in this embodiment, a portion of the steel column 20, including the lower end 20a, is covered with the covering concrete portion 40, which further increases the strength of the underground structure 2 and allows the steel column 20 of the building 3 to be more effectively supported by the underground structure 2.

[0031] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0032] For example, in the above embodiment, a portion of the side wall 30d of the lower end 30 of the intermediate steel frame 30 is placed on the internal steel frame 10a of the existing column 10 via the diaphragm 32 and the protrusion 43, but this is not limited to this. As long as a portion of the side wall 30d of the lower end 30b of the intermediate steel frame 30 is placed on the internal steel frame 10a, various configurations may be used, such as a configuration in which a portion of the side wall 30d of the lower end 30b of the intermediate steel frame 30 is placed directly on the internal steel frame 10a.

[0033] Furthermore, the intermediate steel frame 30 may have various shapes as long as it has a shape that expands diagonally from the upper end 30a to the lower end 30b, so that it is connected to the lower end 20a of the steel column 20 at the upper end 30a and a portion of the lower end 30b is placed on top of the internal steel frame 10a of the existing column 10.

[0034] Furthermore, in this embodiment, the underground structure 2 is configured such that, in the portion having the existing column 10 and the new column 50, a new beam 50 having a rectangular horizontal cross section of the same width as the existing column 10 is arranged adjacent to one side of the existing column 10, which has a square horizontal cross section.However, this is not limited to this, and the configuration can be modified in various ways, for example, in the portion having the existing column 10 and the new column 50, a new beam 50 having an L-shaped horizontal cross section is arranged adjacent to two adjacent sides of the existing column 10, which has a square horizontal cross section. [Explanation of symbols]

[0035] 1. Building structure 2 Underground structure 3. Building 10 Existing pillar 10a Internal steel frame 10b Concrete section 10c Reinforced concrete 10d top end 10e Side 11 Existing beam 12 New beam 20 Steel column 20a bottom end 20b center 21 Pillar body 22 Joint 23 Diaphragm 24 Concrete 25 New beam 30 Intermediate steel frame 30a top end 30b bottom end 30c side wall 30d side wall 30e side wall 30f side wall 31 Diaphragm 32 diaphragm 33 Reinforced concrete 34 studs 35 Concrete 40 Covering concrete section 41 Lower part 42 Upper part 43 Protrusion 44 Covering part 45 Covering part 50 New Pillars O1 center axis O2 center axis

Claims

1. The existing reinforced concrete columns that make up the underground structure, a steel column whose lower end center is horizontally shifted from the central axis of the internal steel frame of the existing column; an intermediate steel frame having a shape that expands obliquely from its upper end to its lower end, the intermediate steel frame being connected at its upper end to the lower end of the steel column and having a portion of its lower end disposed on the inner steel frame; A building structure characterized by having a covering concrete section that covers the existing columns and the intermediate steel frame.

2. The building structure according to claim 1 , wherein a portion of the steel column including its lower end is covered by the covering concrete portion.

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