JP7680934B2 - staircase structure - Google Patents

Description

The present invention relates to a staircase structure that includes a support girder installed between an upper floor and a lower floor, and a plurality of tread sections supported on the support girder.

Conventionally, there is known a staircase structure in which a plurality of tread sections are supported on a single support girder installed between an upper floor section and a lower floor section. In such a staircase structure, the support girder is generally provided at the center of the tread sections in the left and right directions so that torsional stress is not generated in the support girder (for example, see Patent Document 1).
In addition, in the staircase structure described in Patent Document 1, a pair of left and right connecting members (8) are provided on each of the multiple step sections to connect the step section to the support girder.

Japanese Utility Model Application Publication No. 04-056838

Due to design requirements and surrounding conditions, it may be unavoidable to adopt an offset support girder installation structure in which the support girder is positioned to one side relative to the center of the left and right parts of multiple step sections.
When adopting such a support girder offset installation structure, torsional stress occurs in the support girder in the staircase structure as described in the above-mentioned Patent Document 1. Therefore, it is necessary to confirm the member strength by adding the shear stress caused by torsion to the shear force for the member design of the support girder, and it is also necessary to consider the torsion angle of the support girder due to the torsional stress, and in the design, it was necessary to change the cross section of the support girder to a larger one to satisfy the increased stress and deformation.

In view of this situation, the main objective of the present invention is to provide a technology that can appropriately handle the torsional stress generated in a support girder when adopting a support girder offset installation structure in which the support girder is installed in a position offset to one side from the left-right center of the multiple tread sections in a staircase structure that includes a support girder installed between an upper floor section and a lower floor section and multiple tread sections supported on the support girder, while suppressing the cross-sectional expansion of the support girder and achieving rationalization.

The first characteristic configuration of the present invention is a support girder installed between an upper floor portion and a lower floor portion,
A plurality of step portions supported on the support girder,
A staircase structure having a support girder offset installation structure in which the support girder is provided at a position offset to one side with respect to the left and right central portions of the plurality of step sections,
A pair of left and right connecting members are provided for connecting both ends of each of the plurality of step portions to the support beam,
The present invention has a connecting member axis offset structure in which the axis of at least one of the pair of left and right connecting members is offset relative to the axis of the support girder, thereby canceling out the torsional stress generated in the support girder due to the support girder offset installation structure.

According to this configuration, the connecting member axis offset structure is adopted, and the axis of at least one of the pair of left and right connecting members connecting both ends of the tread portion to the support girder is offset with respect to the axis of the support girder, so that the axial force is transmitted to a position in the support girder that is offset from the axis of at least one of the pair of left and right connecting members, generating eccentric bending stress. The torsional stress generated in the support girder due to the offset support girder installation structure can be countered by the eccentric bending stress generated in the support girder due to the connecting member axis offset structure.
Therefore, the present invention provides a technology that can appropriately handle the torsional stress generated in the support girder while suppressing the cross-sectional expansion of the support girder and achieving rationalization in a staircase structure having a support girder erected between an upper floor and a lower floor, and a plurality of tread sections supported on the support girder, by adopting a support girder offset installation structure in which the support girder is positioned at a position shifted to one side relative to the left-right center of the plurality of tread sections.

The second characteristic configuration of the present invention is that the pair of left and right connecting members includes a short side connecting member located on the side of the shift direction of the support girder with respect to the left and right center of the tread portion, and a long side connecting member located on the opposite side to the shift direction side,
The connecting member axis offset structure is characterized in that the axis of the long side connecting member passes above the axis of the support girder, and the axis of the short side connecting member passes below the axis of the support girder.

According to this configuration, the rotation direction of the torsional stress generated by the support girder offset installation structure in the support girder is the rotation direction in which the offset side of the support girder with respect to the left and right central part of the tread part faces upward. On the other hand, the rotation direction of the eccentric bending stress generated by the adoption of the connecting member axis offset structure in the support girder is the rotation direction in which the long side connecting member side, i.e., the opposite side to the offset side of the support girder with respect to the left and right central part of the tread part faces upward, since the axis of the long side connecting member passes above the axis of the support girder and the axis of the short side connecting member passes below the axis of the support girder. Therefore, by adopting such a rational configuration, the rotation direction of the eccentric bending stress generated by the adoption of the connecting member axis offset structure in the support girder is set in the opposite direction to the rotation direction of the torsional stress generated by the support girder offset installation structure, and the torsional stress can be suitably countered by the eccentric bending stress.

The third characteristic feature of the present invention is that the connection portions of the pair of left and right connecting members to the outer surface of the support girder are provided at the same height.

According to this configuration, for example, when the support girder is constructed of a steel pipe with an axis passing through it, the above-mentioned connecting member axis offset structure is adopted, and the connection points of the pair of left and right connecting members to the outer surface of the support girder can be set at the same height, improving the design of the exterior.

A side view of the staircase structure of this embodiment. A front cross-sectional view of the staircase structure of this embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a staircase structure according to the present invention will be described with reference to the drawings.
As shown in Figures 1 and 2, the staircase structure 1 of this embodiment includes a support girder 10 installed between an upper floor section F1 and a lower floor section F2, and a plurality of tread sections 20 supported on the support girder 10. In the following description, the horizontal direction along the ascending and descending direction of the stairs may be expressed as the front-rear direction (the left-right direction of the paper in Figure 1, the direction perpendicular to the paper in Figure 2), and the horizontal direction perpendicular thereto may be expressed as the left-right direction (the direction perpendicular to the paper in Figure 1, the left-right direction of the paper in Figure 2).

The support girder 10 is made of a round steel pipe with a circular cross section, and one support girder 10 is erected between the upper floor section F1 and the lower floor section F2, with multiple tread sections 20 supported on that single support girder 10.
The step section 20 is constructed by placing a step plate 21 made of flat steel in a horizontal position on a support plate 22 made of a steel strip extending in the left-right direction in a vertical position, and welding them together. Column joints 22a are provided at both ends of the support plate 22, which extend upward and to which the lower ends of handrail posts 40 are bolted. The handrail 41, which is installed between the upper floor section F1 and the lower floor section F2, is joined to the upper end of the handrail post 40 joined to the support joints 22a.
Furthermore, the step plate 21 of each step portion 20 and the support girder 10 are joined via a fixing plate 25 that extends in the front-rear direction in a vertical position. That is, the upper end of this fixing plate 25 is welded to the lower surface of the step plate 21, and the lower end is welded to the upper surface of the support girder 10.

In the staircase structure 1 of this embodiment, as shown in Figure 2, a support girder offset installation structure is adopted in which the support girder 10 is provided at a position offset to one side from the left-right central portion 20a of the multiple tread portions 20. In other words, the axis 10a of the support girder 10 passes through a position offset in a predetermined offset direction A (to the right in Figure 2) to the side from the left-right central portion 20a of the multiple tread portions 20, and a fixed plate 25 is interposed between the axis 10a and the tread plate 21 of the tread portion 20 on a vertical plane passing through the axis 10a.

In the staircase structure 1 employing such a support girder offset installation structure, a rotational moment is transmitted in addition to a vertical load from the tread portion 20 to the support girder 10 via the fixed plate 25. This generates a torsional stress in the support girder 10 in a rotational direction (counterclockwise in FIG. 2 ) in which the offset direction A of the support girder 10 relative to the left-right central portion 20a of the tread portion 20 faces upward.
In the staircase structure 1 of this embodiment, a connecting member axis offset structure is adopted to cancel out the torsional stress generated in the support girder 10, and the details of this structure are described below.

A pair of left and right connecting members 30 are provided on each of the plurality of tread portions 20, connecting both ends 20b of the tread portion 20 to the support girder 10. The connecting members 30 are made of steel bars, and their upper ends are welded to the support plates 22 at both ends 20b of the tread portion 20, and their lower ends are welded to the outer surface of the support girder 10.
The above-mentioned connecting member axis offset structure is configured to offset the axes of both of the pair of left and right connecting members 30 relative to the axis 10a of the support girder 10, thereby canceling out the torsional stress generated in the support girder 10 due to the support girder offset installation structure.

Specifically, the pair of left and right connecting members 30 consists of a short side connecting member 31 located on the side of the shift direction A of the support girder 10 relative to the left and right central portion 20a of the tread portion 20, and a long side connecting member 32 located on the opposite side of the shift direction A. As shown in Figure 2, the connecting member axis offset structure is configured such that the axis 32a of the long side connecting member 32 passes through a position above the axis 10a of the support girder 10 (position indicated by a circle in Figure 2), and the axis 31a of the short side connecting member 31 passes through a position below the axis 10a of the support girder 10 (position indicated by a triangle in Figure 2).

This type of connecting member axis offset structure is adopted, and the axes 31a, 32a of the pair of left and right connecting members 30 that connect both ends 20b of the tread portion 20 to the support girder 10 are offset relative to the axis 10a of the support girder 10, so that the compressive axial force is transmitted from each of the pair of left and right connecting members 30 to a position offset from the axis 10a in the support girder 10, generating eccentric bending stress. Furthermore, the rotation direction of the eccentric bending stress generated in the support girder 10 in this way is a rotation direction (clockwise rotation direction in Figure 2) in which the side opposite to the offset direction A of the support girder 10 relative to the left and right central portions 20a of the tread portion 20 faces upward, since the axis 32a of the long side connecting member 32 passes above the axis 10a of the support girder 10 and the axis 31a of the short side connecting member 31 passes below the axis 10a of the support girder 10.

As described above, in the support girder 10, the rotational direction of the eccentric bending stress caused by adopting the above-mentioned connecting member axis offset structure (clockwise rotational direction in FIG. 2) is set in the opposite direction to the rotational direction of the torsional stress caused by adopting the above-mentioned support girder offset installation structure (counterclockwise rotational direction in FIG. 2). Therefore, the torsional stress caused in the support girder 10 by the above-mentioned support girder offset installation structure can be suitably counteracted by the eccentric bending stress caused in the support girder 10 by the above-mentioned connecting member axis offset structure. And, because the torsional stress of the support girder 10 is suitably counteracted, the cross-sectional expansion of the support girder 10 can be suppressed, thereby achieving rationalization.

Furthermore, by adjusting the offset width of each of the axes 31a, 32a of each of the connecting members 30 in the above-mentioned connecting member axis offset structure according to the degree of offset of the axis 10a of the support girder 10 relative to the left and right central portion 20a of the tread portion 20 in the above-mentioned support girder offset installation structure (for example, the ratio of the extension length to the left and right of the tread portion 20 based on the axis 10a position of the support girder 10), the above-mentioned torsional stress generated in the support girder 10 can be completely canceled by the above-mentioned eccentric bending stress. Also, if the offset width of each of the axes 31a, 32a of the connecting members 30 cannot be sufficiently secured due to factors such as the size of the support girder 10, the degree of offset of the axis 10a of the support girder 10 can be alleviated so that the above-mentioned torsional stress is completely canceled by the above-mentioned eccentric bending stress.

Furthermore, as shown in FIG. 2, the connection portions 31b, 32b of the pair of left and right connecting members 30 to the outer surface of the support girder 10 are provided at the same heights H1, H2. That is, the height H1 of the connection portion 31b of the short side connecting member 31 to the outer surface of the support girder 10 and the height H2 of the connection portion 32b of the long side connecting member 32 to the outer surface of the support girder 10 are set to be the same. This improves the design of the appearance of the support girder 10 made of round steel pipes while adopting the connecting member axis offset structure described above.

[Another embodiment]
Other embodiments of the present invention will be described below. Note that the configurations of the embodiments described below are not limited to being applied alone, but may also be applied in combination with the configurations of other embodiments.

(1) In the above embodiment, the connecting member axis offset structure employs a configuration in which both axes of the pair of left and right connecting members 30 are offset relative to the axis 10a of the support girder 10, but a configuration in which only one axis of the pair of left and right connecting members 30 is offset may also be employed. For example, when only the axis 32a of the long side connecting member 32 is offset, the axis 32a of the long side connecting member 32 can pass above the axis 10a of the support girder 10, and the axis 31a of the other short side connecting member 31 can pass through the axis 10a of the support girder 10. Conversely, when only the axis 31a of the short side connecting member 31 is biased, the axis 31a of the short side connecting member 31 can pass through a position below the axis 10a of the support girder 10, and the axis 32a of the other long side connecting member 32 can pass through the axis 10a of the support girder 10. In either configuration, the rotation direction of the eccentric bending stress generated by the adoption of the connecting member axis bias structure can be set in the opposite direction to the rotation direction of the torsional stress generated by the support girder offset installation structure in the support girder 10, so that the torsional stress can be suitably counteracted by the eccentric bending stress.

(2) In the above embodiment, the connection parts 31b, 32b of the pair of left and right connecting members 30 to the outer surface of the support girder 10 are provided at the same height H1, H2, but the height at which these connection parts 31b, 32b are provided can be changed as appropriate, and they do not have to be provided at the same height.

(3) In the above embodiment, the support girder 10 is made of a round steel pipe with a circular cross section, but the material that makes up the support girder 10 can be changed as appropriate. For example, steel material with a cross-sectional shape such as an ellipse, rectangle (quadrangle), polygon, or H-shape can be used as the support girder 10.

1 Staircase structure 10 Support girder 10a Axis 20 Tread section 20a Left and right central section 20b Both ends 30 Connecting member 31 Short side connecting member 31a Axis 31b Connection portion 32 Long side connecting member 32a Axis 32b Connection portion A Displacement direction F1 Upper floor section F2 Lower floor section H1 Height H2 Height

Claims (3)

A support girder installed between the upper floor and the lower floor;
A plurality of step portions supported on the support girder,
A staircase structure having a support girder offset installation structure in which the support girder is provided at a position offset to one side with respect to the left and right central portions of the plurality of step sections,
A pair of left and right connecting members are provided for connecting both ends of each of the plurality of step portions to the support beam,
A staircase structure having a connecting member axis offset structure in which the axis of at least one of the pair of left and right connecting members is offset relative to the axis of the support girder, thereby canceling out the torsional stress generated in the support girder due to the support girder offset installation structure. The pair of left and right connecting members includes a short-side connecting member located on the side of the support girder in the shift direction relative to the left and right center of the tread portion, and a long-side connecting member located on the opposite side to the shift direction,
The staircase structure described in claim 1, wherein the connecting member axis offset structure is a structure in which the axis of the long side connecting member passes above the axis of the support beam and the axis of the short side connecting member passes below the axis of the support beam. 3. The staircase structure according to claim 1, wherein the connection portions of the pair of left and right connecting members to the outer surface of the support beam are provided at the same height.

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