JP7449143B2 - building frame structure - Google Patents

Description

The present invention relates to a building frame structure that cantilever-supports a structure extending outward from the building.

In the frame of a building, a pair of braces arranged in an X-shape within the frame of a building are generally both made of highly rigid steel frames.
As a special example, out of a pair of braces arranged in an A frame structure composed of braces is known (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2005-325529

However, in the frame of a building that supports a structure on a cantilever, there are floating columns that are subject to an upward lifting force due to the unbalanced load caused by the structure's cantilever support, so they are arranged in an X-shape. If the pair of braces are both highly rigid braces made of steel frames, there is a risk that the column to be floated will float when a large external force is applied to the frame due to an earthquake or the like.
In other words, a lifting force is always acting on the floating column, so if a large external force is applied to the frame due to an earthquake, etc., an even greater lifting force is applied to the floating column, causing it to float upward. there is a possibility.
Incidentally, although the technology described in Patent Document 1 consists of one brace having a high rigidity and the other brace having a low rigidity, the technology described in Patent Document 1 can be used even after large vibrations such as a major earthquake are input. This patent also relates to a technique for suppressing the occurrence of residual deformation and the amount of residual deformation in a frame portion or a brace, and does not relate to a frame portion having a column to be floated.

The present invention has focused on such conventional problems, and its purpose is to prevent the lifting of the lifting column even if a large external force is applied to the frame due to an earthquake etc. The object of the present invention is to provide a building frame structure that can reliably prevent the above.

A first characteristic configuration of the present invention is a building frame structure that cantilever-supports a structure extending outward from the building, wherein an upward lifting force is generated due to an unbalanced load due to the cantilever support of the structure. In a frame section having a floating target column that acts, of a pair of braces arranged in an X shape within the structural surface of the frame section, the first brace connected to the lower end of the floating target column is a low-rigidity brace. The second brace connected to the upper end of the floating object column is a highly rigid brace.

According to this configuration, of the pair of braces arranged in an X shape on the frame having the levitation target column, the first brace connected to the lower end of the levitation target column has low rigidity and is easily deformed. Because it is composed of braces, if a large external force acts on the frame due to an earthquake, for example, and the upper side of the frame tries to deform toward the structure that is the cause of the unbalanced load, the low-rigidity first Since the brace is stretched and deformed, the floating force applied to the floating target column is reduced.
In other words, an uplifting force is always acting on the uplifting target column under normal conditions, and there is a risk that an even greater uplifting force will be added due to earthquakes, etc. However, since the uplifting force that should be added is reduced, even if the uplifting force is Even in the event of an earthquake, the lifting of the target pillar is reliably prevented.
Since the other second brace is composed of a high-rigidity brace, the frame section having the floating target column as a whole has a rational structure with a well-balanced rigidity and resistance that can sufficiently cope with earthquakes. Become.

A second characteristic configuration of the present invention is that a plurality of frame parts having the levitation target column are arranged in a state in which the levitation target column is shared, and in each of the plurality of frame parts, the first brace is a low-rigidity brace. The second brace is made of a highly rigid brace.

According to this configuration, in each of the plurality of frame parts that share the levitation target column, the first brace is configured with a low-rigidity brace, so even though the plurality of frame parts share the levitation target column, the earthquake When this occurs, the levitation force acting on the levitation target column is reliably reduced. Since the second brace of each frame part is constituted by a high-rigidity brace, each frame part that shares the floating target column has a rational structure with a good balance of rigidity and proof stress.

A third feature of the present invention is that the first brace is made of reinforcing bars, and the second brace is made of steel.

According to this configuration, since the first brace connected to the lower end of the levitation target column is made of reinforcing bars, the low rigidity of the reinforcing bars is effectively used to reliably reduce the levitation force applied to the levitation target column. can do. Since the other second brace is made of steel, it is possible to construct a rational frame with a good balance of rigidity and strength by using relatively inexpensive and easily available reinforcing bars and steel frames. be able to.

A fourth feature of the present invention is that the structure is a roof.

According to this configuration, since the structure that extends outward from the building and is supported in a cantilever manner is the roof, it is possible, for example, to support a large roof that covers a plaza or the like in various commercial facilities in a cantilever manner on the building. It is possible to reliably prevent the column to be floated from floating due to the unbalanced load on the roof.

Schematic plan showing the frame structure of the building II-II line arrow view in Figure 1

Embodiments of a building frame structure according to the present invention will be described based on the drawings.
As shown in FIGS. 1 and 2, the building according to the present invention is, for example, a building 3 for a commercial facility equipped with a large number of steel columns 1, a large number of steel beams 2, etc. A roof 5, which is an example, is attached to the building 3, separately from the roof 4 of the building 3, through a connecting member 6 so as to protrude outward from the building 3 and cover a plaza, sidewalk, etc. That is, the present invention relates to a building 3 in which a roof 5 as a structure projecting outward from the building 3 is supported in a cantilever manner, and relates to a frame structure of the building 3.
In such a building 3, referring to FIG. 2, a floating target column 7 is subjected to an upward lifting force F due to an uneven load L caused by cantilever support of a roof 5, which is a structure, on a large number of columns 1. occurs. The levitation target column 7 mainly corresponds to the column 1 located farthest from the center of the unbalanced load L, and another pillar 1 located between the farthest levitation target column 7 and the center of the unbalanced load L is the fulcrum. Thus, a lifting force F is applied to the floating target column 7, and it relates to the structure of the frame section 8 having such a floating target column 7.

As shown in FIG. 2, the frame section 8 includes, for example, a normal column 1 adjacent to the floating target column 7 erected on a reinforced concrete foundation 9, a beam 2 connecting both columns, and a reinforced concrete foundation 9. It is equipped with a foundation beam 10 made of steel, and studs 11 as necessary.
In the structural surface of the frame section 8, a pair of braces 12 and 13 are connected to the lower end of the floating target column 7 via a first lower end gusset plate 14a, and a first upper end is connected to the upper end of the adjacent normal column 1. The first brace 12 is connected via a gusset plate 14b, and the first brace 12 is connected to the lower end of the regular column 1 via a second lower end gusset plate 15a, and the upper end of the floating target column 7 is connected via a second upper end gusset plate 15b. The second brace 13 to be connected is arranged in an X shape.
In the illustrated example, since the braces are long, the first brace 12 is divided into two braces 12a and 12b, and the second brace 13 is also divided into two braces 13a and 13b, each of which is connected via an intermediate connection plate 16. Although they are connected and arranged in a substantially X shape, if the braces are short, one first brace 12 and one second brace 13 will be arranged in an X shape.

In the frame section 8 having such a floating object column 7, among the pair of braces 12 and 13 arranged in an X shape, the first brace 12 connected to the lower end of the floating object column 7 is a low-rigidity brace. For example, the second brace 13, which is made of reinforcing bars and connected to the upper end of the levitation target column 7, is made of a high-rigidity brace, for example, a steel frame made of various shaped steels such as H-shaped steel. In the illustrated example, the first brace 12 is composed of two reinforcing bars, but depending on the rigidity and strength of the frame section 8, it may be composed of one reinforcing bar, or it may be composed of three reinforcing bars. It is also possible to construct it with the above reinforcing bars.
Further, referring to the plan view of FIG. 1, the floating target pillars 7 are mainly located at the lower left corner and the lower right corner which are farthest from the center of the roof 5, and each floating target pillar 7 is shared. , there are two frame parts 8 that are perpendicular to each other in plan view, and in each of these frame parts 8, the first brace 12 is a low-rigidity brace made of reinforcing steel, and the second brace 13 is a high-rigidity brace made of steel. configured. However, depending on the scale and structure of the building 3, there may be only one frame section 8 having the floating target column 7, or there may be three or more, but the present invention is applicable to either case.

[Another embodiment]
In the previous embodiment, an example was shown in which the first brace 12 was made of reinforcing bars and the second brace 13 was made of steel frames, but these first braces 12 and second braces 13 may be made of various steel materials other than reinforcing bars or steel frames. It can also be configured.
Moreover, although the roof 5 was illustrated as an example of a structure , it is applicable to the frame part 8 of the building 3 which cantilever-supports various structures, such as a balcony and a sundeck, for example.

3 Building 5 Roof as a structure 7 Lifting target column 8 Frame section 12 First brace 13 Second brace L Unbalanced load F Lifting force

Claims (4)

A building frame structure that cantilever-supports a structure that extends outward from the building,
Of a pair of braces arranged in an X-shape within the structural surface of the frame in a frame having a floating column on which an upward lifting force acts due to an unbalanced load due to cantilever support of the structure. A building frame structure in which a first brace connected to the lower end of the floating target column is a low-rigidity brace, and a second brace connected to the upper end of the floating target column is a high-rigidity brace. A plurality of frame sections having the levitation object column are arranged in a state in which the levitation object column is shared, and in each of the plurality of frame sections, the first brace is a low-rigidity brace and the second brace is a high-rigidity brace. The building frame structure according to claim 1, which is comprised of braces. 3. The building frame structure according to claim 1, wherein the first brace is made of reinforcing bars, and the second brace is made of steel. The building frame structure according to any one of claims 1 to 3, wherein the structure is a roof.

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