JP7840722B2 - Supports for cantilevered stairs and cantilevered stairs - Google Patents

Description

This disclosure relates to a support for a cantilevered staircase and a cantilevered staircase.

Conventionally, cantilevered staircases are known in which one end of the tread is fixed and supported to a structural member such as a column. Cantilevered staircases are selected based on structural requirements and design requirements of the building. Because only one end of the tread is fixed, sufficient strength must be ensured. One means of improving the strength of a cantilevered staircase is to make the tread sufficiently thick (see, for example, Patent Document 1).

Japanese Patent Publication No. 2017-036639

In recent years, there has been a demand to reduce the thickness of treads in cantilevered staircases in order to improve their aesthetic appeal. The technology disclosed in Patent Document 1 involves fastening a pair of tread supports together at a support fastening section, with the tread supports positioned to clamp the column at a column clamping section. The treads are then placed to cover the tread supports. The structure disclosed in Patent Document 1 required the tread supports and treads to be thicker than a predetermined thickness in order to ensure sufficient strength for the cantilevered staircase. Besides the technology disclosed in Patent Document 1, another possible method to improve the strength of a cantilevered staircase without increasing the tread thickness is to place and fix a support device, roughly triangular in shape when viewed from the front, beneath the tread so that two sides are in contact with the structural member and the tread. However, since this support device protrudes from the bottom of the tread, it is not necessarily desirable from an aesthetic standpoint, and other methods were needed.

This disclosure is made in view of the above, and aims to provide a support for a cantilevered staircase that can ensure sufficient strength of the cantilevered staircase, and can improve the aesthetic design of the cantilevered staircase by making the thickness of the treads thinner than conventional models.

This disclosure relates to a support for a cantilevered staircase, which fixes and supports one end of a stair tread to a structural member, and comprises a lower support positioned below the tread and fixed to the lower surface of the one end of the tread and to the structural member, and an upper support positioned above the tread and fixed to the upper surface of the one end of the tread and to the structural member.

A perspective view showing a cantilevered staircase equipped with a support according to one embodiment of the present disclosure. This is an enlarged perspective view of Figure 1. Figure 1 shows the support and cantilevered staircase viewed from the front-to-back direction of the tread. This is a perspective view showing a support and footboard according to an embodiment or comparative example of the present disclosure. This is a perspective view showing a support and footplate according to an embodiment of the present disclosure. This is a perspective view showing a support and footplate according to an embodiment of the present disclosure. This is a perspective view showing a support and footplate according to an embodiment of the present disclosure. This graph shows the amount of deflection of the footboards according to the embodiments and comparative examples of this disclosure.

<Cantilevered staircase>
As shown in Figure 1, the cantilevered staircase 1 according to this embodiment is constructed such that one end of each of the multiple treads 10 is fixed and supported to a column 2, which serves as a structural member, by a lower support 21 and an upper support 22, respectively. In the following description, the structural member to which the treads 10 are fixed will be described as the column 2. On the other hand, the object to which the treads 10 are fixed is not limited to a column, but should have a predetermined strength or greater, at least capable of supporting the weight of the user of the cantilevered staircase 1. The above object may be, for example, a beam. In the drawings, the width direction of the tread 10 is indicated as the X1 direction and the X2 direction, the front-to-back direction of the tread 10 is indicated as the Y direction, and the vertical direction is indicated as the Z direction, respectively.

(Footboard)
As shown in Figure 2, the tread 10 is a plate-shaped member having a length L1 in the front-to-back direction, a length L2 in the width direction, and a thickness (vertical length) T. At one end of the tread 10, in the X1 direction, the upper surface (tread) 10a of the tread 10 is fixed to the upper support 22, and the lower surface 10b of the tread 10 is fixed to the lower support 21. The other end of the tread 10, in the X2 direction, is not fixed. In this embodiment, the tread 10 is positioned in contact with the column 2, and the tread 10 and the column 2 may be fixed together. On the other hand, the tread 10 and the column 2 do not have to be fixed together. In addition to the above, the tread 10 and structural members such as the column 2 do not have to be in contact, and may only be in close proximity.

The material of the tread 10 is not particularly limited; a tread made of any material, such as wood or metal, can be used.

The tread plate 10 is fixed by the lower support 21 and upper support 22 according to this embodiment, allowing the thickness T of the tread plate 10 to be made thinner than conventional designs. For example, it can be made 40 mm or less.

(Support)
The support for the cantilevered staircase includes a lower support 21 and an upper support 22. The end of the tread 10 in the X1 direction, which is one end, is clamped vertically by the lower support 21 and the upper support 22 and fixed to the column 2. By configuring the support for the cantilevered staircase to include not only a lower support 21 but also an upper support 22, the amount of deflection of the tread 10 can be reduced. Specifically, when a load is applied to the tread 10, a resistance force from the upper support 22 acts as a reaction to the rotational moment generated with the fixing point between the tread 10 and the lower support 21 as a fulcrum. This reduces the amount of deflection of the tread 10.

The lower support member 21 has an L-shape when viewed from the front-to-back direction of the tread 10, as shown in Figure 3. This lower support member 21 can be obtained, for example, by deforming a metal plate into an L-shape when viewed from the side. One side 211 of the lower support member 21 is fixed to the column 2 by fastening (bolts and nuts) F, for example. The other side 212 of the lower support member 21 is fixed by welding or the like, for example, by contacting the lower surface 10b of the tread 10. Multiple lower support members 21 may be arranged in the front-to-back direction of the tread 10.

The method of fixing the lower support 21 to the tread 10 is not limited to the method described above. Examples of fixing methods include welding, adhesive bonding, and fastening with bolts and nuts.

From an aesthetic standpoint, the shape of the lower support 21 is preferably such that it does not protrude below the tread, such as the L-shape described above. The L-shape of the lower support 21 is just one example of a shape that does not protrude below the tread, and the shape of the lower support 21 is not limited to the L-shape described above.

The widthwise length of the other side 212 of the lower support 21 is not particularly limited and can be set to a length appropriate to the required strength. From an aesthetic standpoint, the thickness (vertical length) of the other side 212 of the lower support 21 is preferably thinner than the thickness T of the tread 10.

The upper support 22 has an L-shape when viewed from the front-to-back direction of the tread 10, as shown in Figure 3. The upper support 22 having this shape can be obtained, for example, by deforming a metal plate into an L-shape when viewed from the side. One side 221 of the upper support 22 is fixed to the column 2 by welding or the like, for example. The other side 212 of the upper support 22 is fixed to the lower surface 10b of the tread 10 by welding or the like, for example. The method of fixing the upper support 22 to the tread 10 is not limited to the above-described method. Examples of fixing methods include welding, adhesive bonding, and fasteners such as bolts and nuts.

The shape of the upper support 22, as viewed from the front-to-back direction of the tread 10, is not particularly limited to an L-shape. It can be rectangular or any other shape, as long as it has a surface that can contact the upper surface 10a of the tread 10 and a surface that can contact the column 2. Specific three-dimensional shapes of the upper support 22 include, for example, a roughly rectangular parallelepiped, a roughly cubic shape, or a roughly triangular prism shape. The above three-dimensional shape may have two mutually perpendicular surfaces, with the other surfaces being composed of either flat or curved surfaces.

Multiple upper support members 22 may be arranged spaced apart in the front-rear direction of the tread 10. This can reduce the material and installation costs of the upper support members 22, and may also achieve the same level of reduction in tread deflection as when using a single upper support member 22.

The length of the portion of the upper support 22 that contacts and fixes to the tread 10 (the other side 222) in the front-to-back direction is preferably 1/4 or more of the length L1 of the tread 10 in the front-to-back direction, and more preferably 2/3 or more. When multiple upper support 22s are arranged, the sum of the lengths of the upper support 22s arranged at both ends of the tread 10 in the front-to-back direction is preferably 1/4 or more of the length L1 of the tread 10 in the front-to-back direction, and more preferably 2/3 or more.

From an aesthetic standpoint, the upper support member 22 is preferably embedded within the wall. In Figure 3, the dashed line 3 indicates the surface of the wall, and the area beyond the dashed line 3 towards the column 2 is inside the wall and therefore not visible from the outside. It is also preferable that one side 211 of the lower support member 21 and the fastener F are embedded within the wall. By giving the lower support member 21 and the upper support member 22 an L-shape when viewed from the front-to-back direction of the tread plate 10, there is the advantage of easily embedding a portion of the lower support member 21 and the upper support member 22 within the wall.

The widthwise length of the other side 222 of the upper support 22 is preferably shorter than the widthwise length of the other side 212 of the lower support 21. The other side 222 only needs to have a widthwise length that can suppress the rotational moment acting approximately vertically upward around the fixing point (fastener F) between the lower support 21 and the column 2 when a load is applied vertically downward to the upper surface 10a of the tread 10. Therefore, the widthwise length of the other side 222 can be shorter than the widthwise length of the other side 212. Furthermore, with the above configuration, the upper support 22 can be easily adjusted to a size that allows it to be embedded inside the wall.

The shape of the upper support 22, when viewed from the front-to-back direction of the tread 10, is preferably L-shaped, and more preferably rectangular. When a load is applied to the tread 10, a rotational moment acting approximately vertically upward on the upper support 22 causes deformation of the upper support 22, potentially causing the tread 10 to deflect. By making the shape of the upper support 22, when viewed from the front-to-back direction of the tread 10, rectangular, the upper support 22 becomes less prone to deformation, thus suppressing the above phenomenon.

The cantilevered staircase and its support structure according to the embodiments of this disclosure have been described above. However, this disclosure is not limited to the embodiments described above, and modifications can be made as appropriate.

The present invention will be described in more detail below based on the examples. However, the present invention is not limited to these examples.

[Deflection Analysis]
Static structural analysis (nonlinear static structural analysis) was performed using a tread 10 having the configuration described above, along with a lower support 21 and an upper support 22, and a tread 10 having the configuration shown in Figures 4 to 7, along with a lower support 21 and upper supports 22a, 22b, 22c, and 22d, with the vertical deformation amount at the end in the X2 direction, which is the other end of the tread 10, defined as the deflection amount. The general-purpose structural analysis software "Optistruct" (manufactured by Altair, (ver. 2021)) was used for the analysis.

<Example 1>
The vertical deformation (deflection) of the end in the X2 direction, which is the other end of the tread 10 fixed by the upper support 22a and lower support 21 shown in Figure 4, was analyzed. The length of the tread 10 in the width direction of the upper support 22a was 6 mm, the vertical length was 27.5 mm, and the front-to-back length was 200 mm. The length of the tread 10 in the width direction was 900 mm, the vertical length (thickness) was 20 mm, and the front-to-back length was 300 mm. The length of the lower support 21 in the width direction was 750 mm, and the front-to-back length was 200 mm. The load applied to the tread 10 was 1200 N. The stress on the tread and wall, and the amount of overhang of the upper support 22a in the width direction of the tread were minimized for the analysis. The analysis result for the deflection of the tread 10 in Example 1 was 4.4 mm.

<Example 2>
The deflection of the tread 10 in Example 2 was analyzed under the same conditions as in Example 1, except that an upper support 22b having the configuration shown in Figure 5 was used. As shown in Figure 5, the upper support 22b consists of two upper supports, upper support 22b1 and upper support 22b2. Upper support 22b1 and upper support 22b2 are arranged on the upper surface of one end of the tread 10, spaced apart along the front-rear direction. Upper support 22b1 and upper support 22b2 have an L-shape when viewed from the front-rear direction of the tread 10. The length of upper support 22b1 and upper support 22b2 in the front-rear direction of the tread 10 was set to 40 mm for both. The analysis result for the deflection of the tread 10 in Example 2 was 4.7 mm.

<Example 3>
The deflection of the tread plate 10 in Example 3 was analyzed under the same conditions as in Example 1, except that an upper support 22 having the configuration shown in Figures 1 to 3 was used. The length of the tread plate 10 in the front-rear direction of the upper support 22 was set to 200 mm. The analysis result for the deflection of the tread plate 10 in Example 3 was 4.1 mm.

<Example 4>
The deflection of the tread 10 in Example 4 was analyzed under the same conditions as in Example 1, except that an upper support 22c having the configuration shown in Figure 6 was used. As shown in Figure 6, the upper support 22c consists of two upper supports, upper support 22c1 and upper support 22c2. Upper support 22c1 and upper support 22c2 are arranged on the upper surface of one end of the tread 10, spaced apart along the front-rear direction. Upper support 22c1 and upper support 22c2 are rectangular when viewed from the front-rear direction of the tread 10 and have a substantially rectangular parallelepiped shape. The length of upper support 22c1 and upper support 22c2 in the front-rear direction of the tread 10 was set to 40 mm for both. The analysis result for the deflection of the tread 10 in Example 4 was 3.3 mm.

<Example 5>
The deflection of the tread 10 in Example 5 was analyzed under the same conditions as in Example 1, except that an upper support 22d having the configuration shown in Figure 7 was used. As shown in Figure 7, the upper support 22d consists of a single member. The upper support 22d is rectangular when viewed from the front-rear direction of the tread 10 and has a substantially rectangular parallelepiped shape. The length of the upper support 22d in the front-rear direction of the tread 10 was set to 200 mm. The analysis result for the deflection of the tread 10 in Example 5 was 3.0 mm.

<Comparative Example 1>
The deflection of the tread plate 10 of Comparative Example 1 was analyzed under the same conditions as in Example 1, except that the upper support 22a was not used. The analysis result for the deflection of the tread plate 10 of Comparative Example 1 was 44.0 mm.

<Comparative Example 2>
The deflection of the tread plate 10 in Comparative Example 2 was analyzed under the same conditions as in Example 1, except that the upper support 22a was not fixed to the tread plate 10. The analysis result for the deflection of the tread plate 10 in Comparative Example 2 was 28.8 mm.

Figure 8 shows the results of the deflection amount of the tread 10 according to the above embodiments and comparative examples. From the results in Figure 8, it is clear that the deflection amount of the tread 10 can be suppressed by fixing one end of the tread 10 together with the lower support 21 using the upper support according to each embodiment. Specifically, it is clear that the shape of the upper support may be L-shaped or rectangular when viewed from the front-to-back direction of the tread 10. Furthermore, it is clear that the upper support having the above shape may be a single component, or multiple upper supports may be arranged spaced apart along the front-to-back direction.

Claims (7)

A support for a cantilevered staircase that fixes and supports one end of a stair tread to a structural member,
A lower support is provided, which is positioned below the footboard and fixed to the lower surface of one end of the footboard and to the structural member.
The tread plate is positioned on the upper part of the tread plate and includes an upper support that is fixed to the upper surface of one end of the tread plate and to the structural member ,
The lower support and the upper support are cantilevered stair support members, each fixed to a surface of the structural member facing the end face of one end of the tread for each tread . A support for a cantilevered staircase that fixes and supports one end of a stair tread to a structural member,
A lower support is provided, which is positioned below the footboard and fixed to the lower surface of one end of the footboard and to the structural member.
The tread plate is positioned on the upper part of the tread plate and includes an upper support that is fixed to the upper surface of one end of the tread plate and to the structural member,
The thickness of the lower support is thinner than the thickness of the tread plate.
A support for a cantilevered staircase, wherein one end of the lower support is embedded inside the wall, and the other end is exposed from the wall. The support for a cantilevered staircase according to claim 1 or 2 , wherein the cross-sectional shape of the upper support when viewed from the front-to-back direction of the tread is either L-shaped or rectangular. The support for a cantilevered staircase according to any one of claims 1 to 3 , wherein the cross-sectional shape of the lower support when viewed from the front-to-back direction of the tread is either L-shaped or rectangular. The support for a cantilevered staircase according to any one of claims 1 to 4 , wherein the upper support members are arranged in a plurality along the front-to-back direction of the tread. The upper support is embedded inside the wall, and is a support for a cantilevered staircase according to any one of claims 1 to 5 . A cantilevered staircase comprising a support for a cantilevered staircase as described in any one of claims 1 to 6 ,
A cantilevered staircase in which the thickness of the aforementioned treads is 40 mm or less.