Stair structure

Abstract

To provide a stair structure including a support girder constructed between an upper story and a lower story, and a plurality of treads supported on the support girder, in which when adopting a support girder shifted installation structure, the torsional stress generated in the support girder is properly handled while accomplishing rationalization by suppressing the cross-sectional expansion of the support girder.SOLUTION: Provided is a stair structure 1 having a support girder shifted installation structure in which a support girder 10 is provided at a position shifted to one side with respect to a left-right center portion 20a of a plurality of treads 20. Each of the plurality of treads 20 has a pair of left and right connecting members 30 that connect both ends 20b of the treads 20 and the support grinder 10. The structure has a connecting member axial center deviation structure in which at least one of shaft cores 31a, 32a of the pair of left and right connecting members 30 is offset with respect to a shaft core 10a of the support girder 10 to cancel the torsional stress generated in the support girder 10 due to the support girder shifted installation structure.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a staircase structure having a support girder installed between an upper floor section and a lower floor section, and a plurality of tread sections supported on the support girder. [Background technology]

[0002] 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 left and right of the plurality of tread sections so that torsional stress is not generated in the support girder (for example, see Patent Document 1). Moreover, in the staircase structure described in Patent Document 1, a pair of left and right connecting members (8) is provided for each of the plurality of step portions, which connects the step portion to the support girder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 04-056838 Summary of the Invention [Problem to be solved by the invention]

[0004] 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 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.

[0005] 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 the support girder while suppressing the cross-sectional expansion of the support girder and achieving rationalization, when adopting a support girder offset installation structure in which the support girder is installed at a position shifted to one side from the left-right center of the multiple tread sections in a staircase structure comprising a support girder erected between an upper floor and a lower floor, and a multiple tread sections supported on the support girder. [Means for solving the problem]

[0006] 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.

[0007] 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.

[0008] 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 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 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.

[0009] 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-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 side opposite to the offset side of the support girder with respect to the left-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 to 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 counteracted by the eccentric bending stress.

[0010] A 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.

[0011] 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 can be adopted, while arranging the connection points of each of a pair of left and right connecting members to the outer surface of the support girder at the same height, thereby improving the design of the appearance. [Brief description of the drawings]

[0012] [Figure 1] A side view of the staircase structure of this embodiment. [Diagram 2] A front cross-sectional view of the staircase structure of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 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 on 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 on the paper in Figure 2).

[0014] 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 then welding them together. In addition, support plate 22 has support column joints 22a connected to both ends thereof, 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 column joints 22a. Furthermore, the step plate 21 of each step portion 20 and the support girder 10 are joined via a fixed plate 25 that extends vertically in the front-to-rear direction. That is, the upper end of this fixed plate 25 is welded to the underside of the step plate 21, and the lower end is welded to the upper surface of the support girder 10.

[0015] As shown in Fig. 2, the staircase structure 1 of this embodiment employs an offset support girder installation structure in which the support girder 10 is provided at a position offset to one side with respect to the left-right central parts 20a of the multiple tread sections 20. That is, the axis 10a of the support girder 10 passes through a position offset in a predetermined offset direction A (rightward in Fig. 2) to the side with respect to the left-right central parts 20a of the multiple tread sections 20, and the fixed plate 25 interposed between the support girder 10 and the tread plate 21 of the tread section 20 exists on a vertical plane passing through the axis 10a.

[0016] 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, the details of which will be described below.

[0017] A pair of left and right connecting members 30 are provided on each of the multiple step sections 20 to connect both ends 20b of the step section 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 step section 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 both axes 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.

[0018] Specifically, the pair of left and right connecting members 30 are composed 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 part 20a of the tread section 20, and a long-side connecting member 32 located on the opposite side to the shift direction A. As shown in Fig. 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 O in Fig. 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 △ in Fig. 2).

[0019] Since such a connecting member axis offset structure is adopted and the axes 31a, 32a of the pair of left and right connecting members 30 connecting both ends 20b of the tread portion 20 to the support girder 10 are offset with respect to the axis 10a of the support girder 10, 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 thus generated in the support girder 10 is a rotation direction (clockwise rotation direction in FIG. 2) in which the side of the long side connecting member 32, i.e., the side opposite to the offset direction A of the support girder 10 with respect to the left and right central portion 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.

[0020] As described above, in the support girder 10, the rotational direction of the eccentric bending stress generated by adopting the above-mentioned connecting member axis offset structure (clockwise rotational direction in FIG. 2) is set to be opposite to the rotational direction of the torsional stress generated by adopting the above-mentioned support girder offset installation structure (counterclockwise rotational direction in FIG. 2). Therefore, the torsional stress generated in the support girder 10 by the above-mentioned support girder offset installation structure can be suitably canceled by the eccentric bending stress generated in the support girder 10 by the above-mentioned connecting member axis offset structure. Furthermore, since the torsional stress of the support girder 10 is suitably canceled, the cross-sectional expansion of the support girder 10 can be suppressed, thereby achieving rationalization.

[0021] Furthermore, by adjusting the offset width of each of the axes 31a, 32a of each of the connecting members 30 in the connecting member axis offset structure described above 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 offset support girder installation structure described above (for example, the ratio of the extension length to the left and right of the tread portion 20 based on the position of the axis 10a of the support girder 10), the torsional stress generated in the support girder 10 can be completely canceled by the 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 may be alleviated so that the torsional stress is completely canceled by the eccentric bending stress.

[0022] 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 employing the above-mentioned connecting member axis offset structure.

[0023] [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.

[0024] (1) In the above embodiment, in the above connecting member axis offset structure, a configuration is adopted in which both axes of the pair of left and right connecting members 30 are offset with respect 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 be adopted. 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 may pass through a position above the axis 10a of the support girder 10, and the axis 31a of the other short side connecting member 31 may pass through the axis 10a of the support girder 10. Conversely, when only the axis 31a of the short side connecting member 31 is offset, the axis 31a of the short side connecting member 31 may 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 may pass through the axis 10a of the support girder 10. In either configuration, in the support girder 10, the rotational direction of the eccentric bending stress generated by the adoption of the connecting member axial core offset structure can be set to be opposite to the rotational direction of the torsional stress generated by the support girder offset installation structure, so that the torsional stress can be suitably counteracted by the eccentric bending stress.

[0025] (2) In the above embodiment, the connection portions 31b, 32b of the pair of left and right connecting members 30 relative to the outer surface of the support girder 10 are provided at the same heights H1, H2, but the heights at which these connection portions 31b, 32b are provided can be changed as appropriate, and they do not have to be provided at the same heights.

[0026] (3) In the above embodiment, the support girder 10 is made of a round steel pipe with a circular cross section, but the material constituting the support girder 10 can be changed as appropriate. For example, a steel material having a cross-sectional shape such as an ellipse, a rectangle (quadrangle), a polygon, or an H-shape can be used as the support girder 10. [Explanation of symbols]

[0027] 1 Stair structure 10 Support beam 10a shaft core 20 Tread section 20a Left and right center 20b Both ends 30 Connecting members 31 Short side connecting member 31a Axis core 31b Connection site 32 Long side connecting member 32a Axis core 32b Connection site A Misalignment direction F1 Upper Floor F2 lower floor H1 Height H2 Height

Claims

1. 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.

2. 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. 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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