JP7601310B2 - Upper floor floor structure - Google Patents

Description

The present invention relates to the floor structure of the upper floor.

There are buildings in which parts of the first floor living room etc. are lowered (recessed). This structure makes the ceiling height in the first floor living room etc. higher, allowing more light to enter the living room etc. from the windows, creating a more open feeling.

On the other hand, in buildings with two or more floors, there is a demand for a structure in which parts of the floors on the upper floors above are lower (or higher) than the other parts. In this way, by making parts of the floors of rooms on the upper floors lower than the other parts, the sense of openness in the rooms on the upper floors can be further enhanced, and various usage options can be added to the rooms on the upper floors.

Although this technology is not related to a floor structure in which the height level of part of the upper floor is relatively low (or high), a skip floor installed, for example, between the first and second floors has been known for some time and is proposed as a skip floor structure in Patent Document 1. This skip floor structure is constructed by constructing a belly beam at the same height level as the floor beams of the general floor section above or below the outer perimeter floor beams of the skip floor, and at key points between this belly beam and the outer perimeter floor beam, a transmission beam is interposed to transmit horizontal force from the outer perimeter floor beam to the belly beam.

JP 2003-166289 A

When the height level of a part of an upper floor is raised or lowered relatively, in a structural analysis of a building including this upper floor, it is desirable from the viewpoint of structural safety to model the part of the floor that has been raised or lowered as an open-ceiling area in the main frame of the floor. One reason for this is that it is difficult to sufficiently transmit horizontal forces, for example during an earthquake, between a part of the floor that has been raised or lowered relatively and other parts of the floor.

In this way, if one were to attempt to raise or lower part of a floor relatively to create an even greater sense of openness in rooms on the upper floors, in structural analysis this part would be considered an open-air area in the main structure of the floor, and the area that can be raised or lowered relatively would inevitably be limited to the upper floors.

The present invention was made in consideration of the above problems, and aims to provide a floor structure for an upper floor that allows high design freedom when the height level of a portion of the floor on the upper floor is relatively raised or lowered without restricting the setting position of the portion of the floor that is raised or lowered.

In order to achieve the above object, one aspect of the floor structure of the upper floor according to the present invention is as follows:
A floor structure of the second or higher floors in a multi-story building,
The upper floor has at least a first floor having a relatively high height level and a second floor having a relatively low height level;
the first floor and the second floor each include a plurality of first floor beams and a plurality of second floor beams;
A ladder beam is disposed at the boundary between the first floor and the second floor, and the first floor beam and the second floor beam are each connected to the ladder beam.

According to this aspect, a ladder beam is arranged on the upper floor at the boundary between the first floor, which is relatively high, and the second floor, which is relatively low, and the first floor beam and the second floor beam are each connected to the ladder beam, so that the horizontal force during an earthquake can be sufficiently transmitted from the first floor to the second floor via the highly rigid ladder beam. Therefore, for example, the setting position of the second floor, which is relatively low, is not limited and it can be set at any position. This is because, since the first floor beam and the second floor beam are connected to a common ladder beam, it is no longer necessary to consider, for example, the second floor, which is relatively low, as an open-ceiling area in the main frame of the upper floor during structural analysis, and it becomes possible to perform structural analysis of the entire area of the floor as the main frame.

This aspect is a floor structure in which ladder beams, which are typically installed on the vertical structural plane of a building, are applied to the boundary between a first floor and a second floor, which are at different floor heights on the upper floors. This aspect increases design freedom, making it possible, for example, to set the relatively low second floor at various positions on the floor. In addition, the space under the floor of the relatively high first floor can be used for underfloor storage, for example, providing usage options for rooms on the upper floors.

In another aspect of the floor structure of the upper floor according to the present invention, the ladder beam comprises at least an upper chord member, a lower chord member, and a plurality of vertical members connecting the upper chord member and the lower chord member,
The first floor beam and the second floor beam are respectively connected to the upper chord and the lower chord.

According to this embodiment, the first floor beam is connected to the upper chord that constitutes the ladder beam, the second floor beam is connected to the lower chord that constitutes the ladder beam, and the upper chord and the lower chord are connected to multiple vertical members, so that the horizontal force during an earthquake can be transmitted from one floor beam through one of the upper chord or the lower chord, through multiple vertical members, and through the other of the upper chord or the lower chord to the other floor beam. Here, the ladder beam may be a beam of a Vierendeel structure in which the vertical members are vertical members, or a beam of a structure in which the vertical members include both vertical members and diagonal members.

It is desirable that the shaped steel material (e.g. H-shaped steel) applied to the first floor beam and the shaped steel material applied to the upper chord to which it is connected are of the same specifications (same dimensions), and it is also desirable that the shaped steel material (e.g. H-shaped steel) applied to the second floor beam and the shaped steel material applied to the lower chord to which it is connected are of the same specifications (same dimensions). In addition, since it is desirable for the vertical member that transmits horizontal forces between the upper chord and the lower chord to be a highly rigid member, it is advisable to use steel pipes, square pipes, etc. for this vertical member.

In addition, in another aspect of the floor structure of the upper floor according to the present invention, a reinforcing plate is attached to the side of the ladder beam from the upper chord to the lower chord,
The second floor beam is connected to the lower chord via the reinforcing plate,
A reinforcing rib is attached to the wide surface of the reinforcing plate, extending from the upper chord to the upper surface of the second floor beam.

According to this embodiment, a reinforcing plate is attached from the upper chord to the lower chord, and a reinforcing rib is further attached to the wide surface of the reinforcing plate, extending from the upper chord to the upper surface of the second floor beam. This reinforcing plate and reinforcing rib particularly reinforce the vertical members, forming a high-strength unit (a unit consisting of vertical members, reinforcing plate, and reinforcing rib) that contributes to the transmission of horizontal forces between the upper chord and the lower chord.

Another aspect of the upper floor structure according to the present invention is characterized in that a first horizontal brace is provided between the first floor beams, and a second horizontal brace is provided between the second floor beams.

According to this aspect, a first horizontal brace is provided between multiple first floor beams, and a second horizontal brace is provided between multiple second floor beams, so that the main frame that constitutes the upper floor is stiffened by each horizontal brace, forming a highly rigid floor structure.

In another aspect of the floor structure of the upper floor according to the present invention, a load-bearing wall frame is provided on the wall of the lower floor of the building,
The ladder beam is characterized in that it has greater rigidity than the load-bearing wall structure.

According to this aspect, the ladder beams installed on the floors of the upper floors have greater rigidity than the load-bearing wall structures installed on the walls of the lower floors of the building, so that in the analytical model used for structural analysis, the ladder beams can be modeled as a rigid beam in its entirety, and structural analysis can be performed with simple modeling. If the ladder beams were weak in rigidity, deformation could occur in the ladder beam model during structural analysis, so that the structural model would need to accurately reproduce and model the actual structure consisting of the upper and lower chords and the multiple vertical members connecting them, and creating the analytical model would take time.

Another aspect of the floor structure for the upper floor according to the present invention is characterized in that only both ends or the vicinity of both ends of the ladder beam are supported by the columns of the lower floor.

According to this aspect, by applying a ladder beam with high rigidity, it is possible to place only two columns on the lower floor that support both ends of the ladder beam or two points near both ends, making it unnecessary to place a separate column between the two points of the ladder beam. Therefore, even if the ladder beam has a large span of, for example, 4P to 8P (P indicates the module, and can be set arbitrarily between 800 mm and 1100 mm, for example, 910 mm wide, depending on the module design specifications), a structure in which two columns support two points near both ends can be applied, so that the floor of the upper floor has a structure with different height levels, and the number of columns on the lower floor that support this floor can be as small as possible, which increases the spatial freedom of the lower floor.

As can be understood from the above explanation, the floor structure for the upper floor of the present invention allows for a high degree of freedom in designing the floor structure for the upper floor, when the height level of a portion of the floor of the upper floor is relatively raised or lowered, without limiting the setting position of the portion of the floor that is raised or lowered.

FIG. 2 is a plan view of an example of a floor structure of an upper floor according to an embodiment. FIG. 2 is a cross-sectional view taken along the arrows II-II in FIG. 1, showing a vertical cross-sectional view along the X-axis of an example of a floor structure. 3A and 3B are both views taken along the III-III arrows in FIG. 1, where (a) is a longitudinal cross-sectional view along the Y axis of an example of a floor structure, and (b) is a longitudinal cross-sectional view along the Y axis of a modified example of the floor structure. FIG. 2 is a view taken along the arrow IV in FIG. 1 . 5 is a view taken along the line VV in FIG. 4, and is a vertical cross-sectional view perpendicular to the longitudinal direction of an example of a ladder beam. 6 is a view taken along the arrow VI in FIG. 1 , and is a side view explaining the connection structure of the ladder beam, the upper chord, and the lower chord. FIG. 13 is a side view showing a reinforced ladder beam.

The floor structure of the upper floor according to the embodiment will be described below with reference to the attached drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[Upper floor structure according to the embodiment]
An example of the floor structure of the upper floor according to the embodiment will be described with reference to Figs. 1 to 7. Here, Fig. 1 is a plan view of an example of the floor structure of the upper floor according to the embodiment. Also, Fig. 2 is a view taken along the arrows II-II in Fig. 1, which is a vertical cross-sectional view along the X-axis of an example of the floor structure, and Figs. 3(a) and (b) are both views taken along the arrows III-III in Fig. 1, Fig. 3(a) is a vertical cross-sectional view along the Y-axis of an example of the floor structure, and Fig. 3(b) is a vertical cross-sectional view along the Y-axis of a modified example of the floor structure. Also, Fig. 4 is a view taken along the arrows IV in Fig. 1, and Fig. 5 is a view taken along the arrows V-V in Fig. 4, which is a vertical cross-sectional view perpendicular to the longitudinal direction of an example of a ladder beam. Furthermore, Fig. 6 is a view taken along the arrows VI in Fig. 1, which is a side view explaining the connection structure of the ladder beam, the upper chord, and the lower chord.

The floor structure 40 of the upper floor shown in FIG. 1 is the floor structure of the second floor of the two-story building 50 shown in FIG. 2. In the case of a three-story building, for example, the floor structure 40 of the illustrated example is applied to the floors of the second and/or third floors. The building 50 of the illustrated example is shown as a rectangular building in plan view, with its longitudinal direction along the X-axis direction and its transverse direction along the Y-axis direction. In both the longitudinal and transverse directions, multiple columns 10 (four in the illustrated example) are erected on the periphery of the building, and between the first floor (1F) and the second floor (2F), the first floor beam 20 constituting the first floor 21 (see FIG. 2) which is relatively high in height level and the second floor beam 25 constituting the second floor 26 (see FIG. 2) which is relatively low are arranged along the X-axis and Y-axis, respectively. The first floor beam 20 on the periphery of the building 50 becomes a girth.

As shown in FIG. 2, the floor structure 40 in the illustrated example is divided into three equal parts in the X-axis direction, with the second floor 26 formed in the central area and the first floor 21 formed in the left and right areas. By providing the low-height second floor 26 in the central area, the height s1 to the ceiling of the second floor 26 is high, forming a room on the second floor with a sense of openness. Although not shown, there are various configurations of the first floor and the second floor in a plan view. For example, the second floor may be provided only in the left area or only in the right area in FIG. 1, or the second floor may be provided only in one of the nine sections in FIG. 1 or in a plurality of sections separated from each other. In addition, the illustrated example shows two configurations of the second floor 26, as shown in FIG. 3(a) and (b). First, an example of the floor structure shown in FIG. 3(a) will be described with reference to FIG. 1, FIG. 2, and FIG. 3(a).

The second floor 26 shown in FIG. 3(a) is the upper area (upper section) of the central area shown in FIG. 1 that is further divided into thirds in the Y-axis direction, and is the first floor 21. Therefore, the second floor 26, which is relatively low in FIG. 1, is the A1 area (the lower two sections) indicated by dots in FIG. 1.

A plurality of first horizontal braces 28A are arranged in an intersecting manner on the horizontal structural surface formed by the plurality of first floor beams 20 that constitute the first floor 21. Similarly, a plurality of second horizontal braces 28B are arranged in an intersecting manner on the horizontal structural surface formed by the plurality of second floor beams 25 that constitute the second floor 26. The horizontal braces 28 are formed, for example, from metal braces, and may have turnbuckles in the middle.

As shown in Figure 2, the first floor beam 20 and the second floor beam 25, which are at different heights, are connected to each other via a ladder beam 30. To explain this with reference to Figure 1, a ladder beam 30A is arranged along the Y axis direction at the boundaries between the central region and the left and right regions of the three equal parts divided in the X axis direction, and both ends of the ladder beam 30A (the upper and lower ends in Figure 1) are connected to the columns 10.

In the example shown in FIG. 3(a), separate ladder beams 30B, 30C are arranged at positions corresponding to the girths in the central region and connected to the column 10, and further, a separate ladder beam 30D is arranged at the boundary between the first floor 21 and the second floor 26 in the central region.

In this way, a ladder beam 30 is arranged at the boundary between the first floor 21 and the second floor 26, which are at different heights, and the first floor beam 20 constituting the first floor 21 and the second floor beam 25 constituting the second floor 26 are connected to the ladder beam 30.

The first floor beam 20 and the second floor beam 25 are both made of H-shaped steel (an example of shaped steel material) of the same standard, and standards such as H-200x100 and H-250x100 can be applied.

As shown in Figures 4 and 5, the ladder beam 30 has an upper chord 34A and a lower chord 34B, and multiple (seven in the illustrated example) vertical members 35 arranged between the upper chord 34A and the lower chord 34B to connect the upper chord 34A and the lower chord 34B.

Both the upper chord 34A and the lower chord 34B are made of H-shaped steel, more specifically, they are made of H-shaped steel of the same standard as the H-shaped steel that forms the first floor beam 20 and the second floor beam 25, and as shown in FIG. 5, both the upper chord 34A and the lower chord 34B have a web 31 and upper and lower flanges 32, 33.

On the other hand, the vertical members 35 are high-rigidity members made of steel pipes, square pipes, etc., and their upper and lower ends are rigidly joined to the upper chord members 34A and lower chord members 34B by welding or bolts. In this specification, "welding" refers to appropriate welding, such as groove welding (full penetration welding, partial penetration welding) and fillet welding, that is selected according to the strength required for the connection and the type of connection (rigid connection, pin connection).

As shown in Figure 4, ladder beams 30 are arranged horizontally in floor structure 40 to form its structural components. As shown in Figure 4, ladder beams 30 are Vierendeel-structured beams in which vertical members 35 are vertical members. Note that the vertical members may also have diagonal members, and the beam may have a structure in which upper chord 34A and lower chord 34B are connected by both vertical members and diagonal members.

As shown in FIG. 6, an end plate 20a is welded to the end of the first floor beam 20, and an end plate 36 is similarly welded to the end of the upper chord member 34A. Both end plates 20a, 36 have bolt holes (not shown) at positions that correspond when they are abutted against each other as shown in the illustrated example, and bolts 39 are inserted into each bolt hole and tightened to form a bolt connection.

Meanwhile, an end plate 20a is welded to the end of the second floor beam 25, and an end plate 36 is similarly welded to the end of the lower chord 34B. Bolts 39 are inserted into bolt holes (not shown) that are opened at corresponding positions in both end plates 20a, 36, and are tightened to form a bolted connection. Note that the upper chord 34A and first floor beam 20, and the lower chord 34B and second floor beam 25 may each be welded together.

Instead of the connection structure shown in FIG. 6, a reinforcing plate 37 may be attached to the side of the ladder beam 30, spanning from the upper chord 34A to the lower chord 34B, as shown in FIG. 7. In this configuration, the second floor beam 25 is bolted to the lower chord 34B via the reinforcing plate 37. A reinforcing rib 38 is welded to the wide surface of the reinforcing plate 37, spanning from the upper chord 34A to the upper surface of the upper flange 25a of the second floor beam 25. For example, the reinforcing structure shown in the figure is effective when the rigidity of the vertical member 35 is low or when it is desired to further increase the rigidity of the ladder beam 30.

In this way, the first floor beam 20 and the second floor beam 25, which are at different heights, are connected to the highly rigid ladder beam 30. Therefore, as shown in FIG. 2, when a horizontal force H during an earthquake acts on the building 50, the horizontal force is transmitted in the Z1 direction from one first floor beam 20 (the first floor beam 20 on the left in the illustrated example) to the second floor beam 25 via one ladder beam 30A, and the horizontal force is transmitted in the Z2 direction from the second floor beam 25 to the other first floor beam 20 (the first floor beam 20 on the right in the illustrated example) via the other ladder beam 30A.

In other words, in a floor structure having floors of different heights, the horizontal force from one floor beam constituting each floor can be sufficiently transmitted to the other floor beam via the ladder beam 30. Therefore, in structural analysis of the upper floors, for example, the lower height parts are not considered to be open-air areas in the main structure of the floor, and a structural model can be constructed and structural analysis can be performed with all areas as the main structure.

More specifically, it is desirable that the ladder beam 30 has greater rigidity than the load-bearing wall structure (not shown) arranged on the vertical structural surface (wall) of the first floor, for example. Since the ladder beam 30 arranged on the floor of the upper floor has greater rigidity than the load-bearing wall structure arranged on the wall of the lower floor of the building, the ladder beam 30 as a whole can be modeled as a rigid beam in the analytical model used for structural analysis, making it possible to perform structural analysis with simple modeling.

In addition, because the first floor beam 20 and the second floor beam 25, which are of different heights, are connected via the ladder beam 30, in a floor structure in which the height level of a portion of the floor of the upper floor rises and falls relatively, the setting position of this rising and falling area is not limited (in the illustrated example, the setting position of the second floor 26 is not limited), resulting in a floor structure with high design freedom.

Furthermore, by using a highly rigid ladder beam 30, structural stability is ensured simply by supporting both ends of the ladder beam 30 with two columns 10, as shown in Figure 1, so there is no need to install additional columns midway along the ladder beam 30, and therefore the design freedom of the lower floor (the first floor in the illustrated example) is increased.

As shown in FIG. 4, the first floor beam 20 (shown as a girth in FIG. 4) that constitutes the first floor 21 and the upper chord 34A of the ladder beam 30 are arranged at the same height level, and therefore the girth of the outer periphery of the building 50 shown in FIG. 1 is formed by the continuity of the first floor beam 20 and the upper chord 34A of the ladder beam 30.

As shown in FIG. 5, the total height t1 of the ladder beam 30 can be set to approximately 500 mm to 800 mm (for example, 600 mm). When H-200 or H-250 is applied to the upper chord 34A and the lower chord 34B, square pipes or the like with a height of approximately 100 mm to 300 mm are applied to the vertical members 35.

In the example shown in FIG. 3(a), the central area (see FIG. 1) has a first floor 21 and a second floor 26, a ladder beam 30D is arranged at the boundary between the first floor 21 and the second floor 26, and the first floor beam 20 constituting the first floor 21 and the second floor beam 25 constituting the second floor 26 are connected to the ladder beam 30. Various options are provided for the second floor, such as using the space below the relatively high first floor 21 as storage space 22.

On the other hand, the example shown in Figure 3(b) is a configuration in which the upper area (upper section) obtained by dividing the central area (see Figure 1) into three equal parts is a completely open atrium 27. In this configuration, the horizontal brace 28 shown by the dotted line in Figure 1 is not necessary.

In this way, even if a void 27 exists in part of the floor, the void 27 is surrounded by highly rigid ladder beams 30, making it possible to perform structural analysis of the entire second floor as the main structure, and increasing the degree of freedom in setting the void's location.

Although not shown, a load-bearing wall structure for the lower floor (first floor in the illustrated example) may be installed below the ladder beam 30, and a load-bearing wall structure for the upper floor (second floor in the illustrated example) may be installed above the ladder beam 30.

Note that the configurations described in the above embodiments may be combined with other components, and the present invention is not limited to the configurations shown here. In this regard, changes can be made without departing from the spirit of the present invention, and can be determined appropriately according to the application form.

10: Pillar 20: First floor beam 21: First floor 22: Storage space 25: Second floor beam 26: Second floor 28: Horizontal brace 28A: First horizontal brace 28B: Second horizontal brace 30, 30A, 30B, 30C: Ladder beam 31: Web 32, 33: Flange 34A: Upper chord 34B: Lower chord 35: Vertical member 36: End plate 37: Reinforcement plate 38: Reinforcement rib 39: Bolt 40, 40A: Floor structure (upper floor floor structure)
50: Two-story building (building)

Claims (4)

A floor structure of the second or higher floors in a multi-story building,
The upper floor has at least a first floor having a relatively high height level and a second floor having a relatively low height level;
the first floor and the second floor each include a plurality of first floor beams and a plurality of second floor beams;
A ladder beam is disposed at the boundary between the first floor and the second floor, and the first floor beam and the second floor beam are each connected to the ladder beam;
The ladder beam includes at least an upper chord member, a lower chord member, and a plurality of vertical members connecting the upper chord member and the lower chord member,
the first floor beam and the second floor beam are connected to the upper chord and the lower chord, respectively;
A reinforcing plate is attached to the side of the ladder beam from the upper chord to the lower chord,
The second floor beam is connected to the lower chord via the reinforcing plate,
A floor structure for an upper floor, characterized in that a reinforcing rib is attached to the wide surface of the reinforcing plate, extending from the upper chord member to the upper surface of the second floor beam. 2. The floor structure of the upper floor according to claim 1 , wherein a first horizontal brace is provided between the plurality of first floor beams, and a second horizontal brace is provided between the plurality of second floor beams. The walls of the lower floor of the building are provided with a load-bearing wall frame,
3. The floor structure for the upper floor according to claim 1 , wherein the ladder beam has a rigidity greater than that of the load-bearing wall structure. 4. The floor structure of the upper floor according to claim 1 , wherein only both ends or the vicinity of both ends of the ladder beam are supported by columns of the lower floor.

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