Staircase, and tread

Abstract

To provide a staircase with improved safety.SOLUTION: A staircase comprises a tread including an FRP layer made of fiber reinforced plastic and a buffer layer arranged to cover at least a part of an underside of the FRP layer and having a hardness lower than that of the FRP layer.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to stairs and treads. [Background technology]

[0002] In recent years, there has been an increase in highly designed stairs, such as skeleton stairs, strip stairs, cantilever stairs, and spiral stairs. The treads are made of, for example, fiber reinforced plastic (hereinafter, sometimes referred to as "FRP"), which has a relatively high hardness. Incidentally, a technology related to an FRP structure including an FRP layer, a thermoplastic resin foam layer, and a sheet-shaped resin layer has been disclosed as an FRP structure (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-035671 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, it has been common to apply anti-slip treatment to the tread surface of staircases and to add cushioning to protect corners, and the underside of the treads has often been left in its raw state without any special treatment. However, for example, in the case of highly designed stairs, where the underside of the treads is exposed, there is a possibility that someone may get under the tread. This means that there is a possibility that the tread may collide with the person's head, etc.

[0005] The present disclosure has been made in consideration of the above problems, and aims to provide a staircase with improved safety. [Means for solving the problem]

[0006] The present disclosure relates to a staircase having a tread including an FRP layer made of fiber-reinforced plastic and a cushioning layer arranged to cover at least a portion of the underside of the FRP layer and having a hardness lower than that of the FRP layer. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a staircase according to a first embodiment. [Diagram 2] FIG. 2 is a side view showing the staircase according to the first embodiment. [Diagram 3] FIG. 2 is a bottom view showing the stairs according to the first embodiment. [Figure 4] FIG. 2 is a top view showing the staircase according to the first embodiment. [Diagram 5] FIG. 5 is a conceptual diagram showing a cross section taken along line AA in FIG. [Figure 6] FIG. 11 is a perspective view showing a staircase according to a second embodiment. [Figure 7] FIG. 11 is a perspective view showing a staircase according to a third embodiment. [Figure 8] FIG. 11 is a perspective view showing a staircase according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] First Embodiment The staircase 100 according to the present embodiment includes a step 10, as shown in Figs. 1 to 3. In each drawing, the longitudinal direction (width direction) of the step 10 is indicated as the X direction, the short side direction (front-rear direction) of the step 10 is indicated as the Y direction, and the vertical direction (thickness direction) is indicated as the Z direction. In the following description, the staircase 100 is described as including a support 20 that supports one end of the step 10 by fixing it to the frame 30. Specifically, the staircase is described as a cantilever staircase in which the other end of the step 10 is not fixed to the frame 30 as shown in Figs. 1 to 3. The staircase according to the present disclosure can also be applied to a double-support staircase in which both ends are supported, and does not need to include the support 20. An example of such a staircase is an open-type staircase that does not have a riser between adjacent steps on the top and bottom. A cantilever staircase or an open-type staircase has a slim appearance and does not have a riser. Therefore, the step is difficult to see and is exposed. Therefore, if a person stands under the step, he or she is likely to collide with the step. The staircase treads according to the present disclosure can reduce the impact when a person collides with the treads, thereby improving the safety of the staircase. On the other hand, the staircase according to the present disclosure may be any staircase in which the underside of the treads is exposed, and may also be a staircase with risers.

[0009] As shown in Figs. 2 and 3, the step 10 is a plate-like member having a length L1X in the X direction, a length L1Y in the Y direction, and a length (thickness) L1Z in the Z direction. The step 10 has a uniform thickness, and the thickness L1Z is preferably 35 mm or less. From the viewpoint of ensuring safety as a residential staircase, the length L1X is preferably 750 mm or more. In Figs. 2 and 3, the step 10 is shown as a rectangular step, but the shape of the step 10 is not limited to a rectangular shape. When the shape of the step 10 is not rectangular, the length L1X in the X direction, the length L1Y in the Y direction, and the length (thickness) L1Z in the Z direction in this specification each refer to the maximum length.

[0010] One end of the step plate 10, the end on the body 30 side, and part of the underside are fixed to the lower support 21. The other end of the step plate 10 is not fixed. With the above configuration, the amount of deflection of the step plate 10 can be reduced even when the thickness L1Z of the step plate 10 is set to 35 mm or less, which is thinner than conventional thicknesses.

[0011] The step 10 may be disposed in contact with the body 30, or may be fixed to the body 30. On the other hand, the step 10 and the body 30 do not have to be directly fixed to each other. In the following description, the body 30 to which the step 10 is fixed is described as a pillar. On the other hand, the object to which the step 10 is fixed is not limited to a pillar, and may be any object having a predetermined strength or more that can support at least the weight of a user of the cantilever staircase. The object may be, for example, a beam or girder.

[0012] As shown in Figures 3 to 5, the step board 10 comprises an FRP layer 11 and a buffer layer 12a. The step board 10 preferably further comprises a buffer layer 12b, a buffer layer 12c, and a design layer 13. Below, the step board 10 will be described as comprising the buffer layer 12b, a buffer layer 12c, and the design layer 13. However, the step board according to the present disclosure may comprise only the FRP layer 11 and the buffer layer 12a, and may not comprise the buffer layer 12b, the buffer layer 12c, and the design layer 13.

[0013] (FRP layer) The thickness of the FRP layer 11 is preferably 10 mm or more and 50 mm or less, which allows for a good balance between the strength and design of the step board 10. The thickness of the FRP layer 11 is more preferably 10 mm or more and 30 mm or less.

[0014] The FRP layer 11 is made of fiber reinforced plastic. The fiber reinforced plastic is not particularly limited, but examples thereof include carbon fiber reinforced plastic and glass fiber reinforced plastic. The FRP layer 11 is preferably made of carbon fiber reinforced plastic (hereinafter, "CFRP"). When the FRP layer 11 is made of CFRP, the CFRP is not particularly limited, but it is preferable that the carbon fiber constituting the CFRP has a Young's modulus (tensile elastic modulus) of 500 GPa or more and a tensile strength of 2000 MPa or more. Examples of the carbon fiber include pitch-based carbon fibers. This can reduce the amount of deflection of the footboard 10 even when the thickness T1 of the FRP layer 11 is 30 mm or less.

[0015] The FRP layer 11 is obtained, for example, by overlapping and bonding CFRP prepreg sheets. The CFRP prepreg sheet is a sheet in which carbon fibers are uniformly impregnated with a matrix resin such as a thermosetting resin or a thermoplastic resin. The CFRP prepreg sheet is preferably one in which the carbon fibers are aligned in a predetermined direction. The FRP layer 11 is preferably configured so that the predetermined direction in which the fibers are oriented is along the X direction of the step board 10. The predetermined direction and the X direction of the step board 10 are preferably approximately parallel, but may have a certain angle. Specifically, the angle between the predetermined direction and the X direction of the step board 10 is preferably 0° or more and less than 45°.

[0016] (buffer layer) The buffer layers 12a and 12b are layers having a lower hardness than the FRP layer 11. The buffer layers 12a and 12b are arranged so as to cover at least a part of the bottom surface or side surface, respectively, of the FRP layer 11. The buffer layers 12a and 12b can reduce the impact when a person collides with the tread 10, thereby improving the safety of the staircase 100.

[0017] The method of disposing the buffer layers 12a, 12b so as to cover a part of the lower surface or side surface of the FRP layer 11 is not particularly limited, but it is preferable to integrally mold the buffer layers 12a, 12b with the FRP layer 11. The FRP layer 11 is formed, for example, by overlapping prepreg sheets impregnated with a matrix resin as described above and heat-curing the matrix resin. Therefore, when the matrix resin is heat-cured, the buffer layers 12a, 12b can be bonded to the FRP layer 11 by abutting the buffer layers 12a, 12b with the prepreg sheets. According to the above integral molding method, the buffer layers 12a, 12b can be easily disposed regardless of the shape of the material constituting the buffer layers 12a, 12b. By integrally molding the buffer layers 12a, 12b with the FRP layer 11, it is possible to prevent the buffer material from falling off due to aging.

[0018] The method of arranging the buffer layers 12a, 12b is not limited to the above, and the buffer layers 12a, 12b formed in advance in a sheet shape may be adhered to the FRP layer 11. The buffer layers 12a, 12b may be arranged so as to cover a part of the lower surface or side surface of the FRP layer 11. The buffer layers 12a, 12b may be in contact with the FRP layer 11 over the entire surface, or only in some places.

[0019] The Shore A hardness of the buffer layers 12a and 12b is preferably not less than 20 and not more than 70. The Asker C hardness of the buffer layers 12a and 12b is preferably not less than 20 and not more than 90. Depending on the hardness range of the buffer layers 12a and 12b, a preferable buffering effect can be obtained.

[0020] The thickness T2a of the buffer layer 12a and the thicknesses T2b, T2c, and T2d of the buffer layer 12b are preferably 5 mm or more and 50 mm or less. The thinner the thickness of the buffer layers 12a and 12b, the slimmer the appearance of the staircase 100 can be realized and the better the design. On the other hand, in order to obtain a preferable cushioning effect, it is preferable to adjust the thickness of the buffer layers 12a and 12b according to the hardness of the buffer layers 12a and 12b and the hardness of the design layer 13. For example, when the thickness of the buffer layers 12a and 12b is 15 mm or less, the Shore A hardness of the buffer layers 12a and 12b is preferably 30 or more.

[0021] Specific examples of materials constituting the buffer layers 12a and 12b include resin, cork, hollow material, and rubber material. The buffer layers 12a and 12b can be composed of at least one of the above materials.

[0022] The resin constituting the buffer layers 12a and 12b is not particularly limited, but examples thereof include expandable resins such as EPS (Expanded Poly-Styrene: bead-method expanded polystyrene), expanded polyethylene, and soft resins such as soft PVC (polyvinyl chloride). As the cork, a material molded by mixing a cork material with a binder such as urethane resin can be used. As the hollow material, a material having a honeycomb structure or a corrugated structure can be used. As the rubber material, natural rubber and synthetic rubber can be used. As the synthetic rubber, examples thereof include silicone rubber, NBR (foamed nitrile rubber), urethane rubber, chloroprene rubber, ethylene rubber, butyl rubber, fluororubber, and the like.

[0023] The buffer layer 12a is a layer arranged to cover at least a part of the lower surface of the FRP layer 11. In this embodiment, the buffer layer 12a is arranged to cover the entire lower surface of the FRP layer 11. The FRP layer 11 and the buffer layer 12a can be easily manufactured by integral molding. On the other hand, the buffer layer 12a may be arranged to cover the area other than the area where the support 20 (lower support 21) described later contacts the step board 10. This can reduce the material cost of the buffer layer 12a, and can improve the design by reducing the total thickness of the step board 10 and the support 20. On the other hand, the buffer layer 12a may be arranged at the area where the support 20 (lower support 21) contacts the step board 10. In this case, for example, the buffer layer 12a at the above area can be crushed to the deformation limit, and then the support 20 (lower support 21) and the step board 10 can be fixed.

[0024] The buffer layer 12b is a layer arranged to cover at least a part of the side surface of the FRP layer 11. In this embodiment, the buffer layer 12b is arranged to cover all of the side surfaces of the FRP layer 11. On the other hand, the buffer layer 12b does not have to cover all of the side surfaces of the FRP layer 11. The thicknesses T2b, T2c, and T2d of the buffer layer 12b can be the same as the thickness T2a of the buffer layer 12a. On the other hand, the thickness of the buffer layer 12b may be thinner than the thickness of the buffer layer 12a. For example, the thicknesses T2b, T2c, and T2d can be thinner than the thickness T2a. This allows a person to easily stand on the footboard 10. Alternatively, the thicknesses T2b, T2c, and T2d of the buffer layer 12b do not have to be the same thickness. Any of the thicknesses T2b, T2c, and T2d may be 0. For example, the thickness (thickness T2b or T2c) of the buffer layer 12b at the end on the lower side is preferably thinner than the thickness of the buffer layer 12b at other locations, and is preferably 30 mm or less. With the above-mentioned configuration, it is possible to prevent a person from accidentally standing only on the buffer layer 12b, from falling off, and to prevent the buffer layer 12b from being damaged.

[0025] In addition to the buffer layers 12a and 12b, the step board 10 may also include a buffer layer 12c as shown in FIG. 5. The buffer layer 12c is disposed at the corners of the FRP layer 11. The above-mentioned corners include the boundary portions between the surfaces of the FRP layer 11. The buffer layer 12c may have a similar structure to the buffer layers 12a and 12b. On the other hand, the buffer layer 12c preferably has a higher hardness than the buffer layers 12a and 12b. Unlike the buffer layers 12a and 12b, the buffer layer 12c comes into contact with the human body at points or lines, and therefore, by having a relatively high hardness, the buffer layer 12c can obtain a favorable buffering effect against high pressure.

[0026] The buffer layers 12a, 12b, and 12c may be made of the same material or a combination of different materials. The buffer layers 12a, 12b, and 12c may be formed as a single unit.

[0027] (Design layer) The design layer 13 is a layer arranged so as to cover at least a part of the outer surface side of the buffer layer. The design layer 13 is a layer that improves the design. In this embodiment, the design layer 13 is arranged so as to cover the entire outer surface side of the buffer layers 12a, 12b, and 12c. On the other hand, the design layer 13 does not have to cover the entire outer surface side of the buffer layers 12a, 12b, and 12c. For example, the design layer 13 can be configured so as not to cover the outer surface side of the buffer layer 12b.

[0028] Specific examples of materials constituting the design layer 13 include fiber reinforced plastics such as CFRP, wrapping sheets, veneers, etc. It is preferable to use woven CFRP as the design layer 13. Woven CFRP is less likely to deform due to impact, so that loss of design can be suppressed. The CFRP may be a PAN-based CFRP having PAN-based carbon fibers as carbon fibers. The tensile strength of the carbon fibers constituting the PAN-based CFRP is preferably 2500 to 7000 MPa. Similarly, the Young's modulus (tensile elastic modulus) of the carbon fibers is preferably 200 to 600 GPa.

[0029] The thickness of the design layer 13 is not particularly limited, but it is preferable that it is as thin as possible in order to improve the design of the staircase 100. The method of arranging the design layer 13 is not particularly limited. The design layer 13 may be integrally formed with the FRP layer and the buffer layer, or may be adhered to the buffer layer. The design layer 13 may be in contact with the buffer layer over the entire surface, or may be in contact with the buffer layer only at certain points.

[0030] (Support) 1 to 3, the support 20 includes lower supports 21 and 23a. The lower supports 21 and 23a are disposed in contact with the lower surface of the step board 10, and support the step board 10 from below.

[0031] The lower supports 21 and 23a and the fixing member 24 are fixed and integrated by a method such as welding. The lower supports 21 and 23a and the fixing member 24 may be bonded to the footboard 10 by a known adhesive.

[0032] (lower support) As shown in Figs. 2 and 3, the lower support 21 is a plate-like member having a length L2X in the X direction, a length L2Y in the Y direction, and a length (thickness) L2Za in the Z direction. The lower support 21 extends from one end (the column 30 side) of the footboard 10 to the other end. The material constituting the lower support 21 is not particularly limited, but is preferably a metal material. Examples of metal materials include steel. The shape of the lower support 21 is not limited to a rectangular shape as shown in Figs. 2 and 3. When the shape of the lower support 21 is not rectangular, the length L2X in the X direction, the length L2Y in the Y direction, and the length (thickness) L2Za in the Z direction each refer to the maximum length.

[0033] The lower support 21 may be provided with a rib 22. The rib 22 is a member that is joined to the lower surface of the lower support 21 by welding or the like and is disposed so as to protrude below the footboard 10. The maximum length of the rib 22 in the Z direction is L2Zb. By providing the lower support 21 with the rib 22, the amount of deflection of the footboard 10 can be further reduced.

[0034] As shown in Fig. 3, the rib 22 is preferably disposed in the center of the lower support 21 in the Y direction. The rib 22 is preferably inclined so that the length in the thickness direction Z tapers from the pillar 30 side toward the tip side of the footboard 10. With the above configuration, the rib 22 can be disposed so as to be difficult to see, improving the design.

[0035] 2 and 3, the lower support 23a is disposed in contact with the underside of one end of the footboard 10, which is on the pillar 30 side. The material constituting the lower support 23a is not particularly limited, but examples thereof include the same metal material as the lower support 21.

[0036] The shape of the lower support 23a is not particularly limited as long as it has a surface that contacts the lower surface of the footboard 10 and a surface that contacts the fixing member 24 perpendicular to the surface. Examples of the shape of the lower support 23a include a substantially rectangular parallelepiped shape, a substantially cubic shape, and a substantially triangular prism shape. From the viewpoint of resistance to deformation due to load, the lower support 23a preferably has a rectangular shape when viewed from the Y direction. On the other hand, the lower support 23a may be embedded inside the wall from the viewpoint of design. In this case, from the viewpoint of ease of embedding inside the wall, the shape of the lower support 23a is preferably an L-shape when viewed from the Y direction.

[0037] The lower support 23a may be a single member as shown in FIGS. 2 and 3, or a plurality of members may be provided along the Y direction of the footboard 10.

[0038] The lower supports 21 and 23a are required to have a certain level of strength to suppress bending of the tread 10. On the other hand, by configuring the lower supports 21 and 23a to be difficult to see, the design of the staircase 100 can be improved. For example, it is preferable that the area S2 of the lower surface of the lower support 21 is 0.71 times or less the area S1. The area S1 can be calculated from the lengths L1X and L1Y, and the area S2 can be calculated from the lengths L2X and L2Y.

[0039] (Fixing member) The fixing member 24 is disposed so as to abut against the upper and lower surfaces of the end portion of the footboard 10 on the pillar 30 side, which is one end side of the footboard 10 , and against the pillar 30 .

[0040] The fixing member 24 is formed with a hole h that communicates in the X direction when the fixing member 24 is disposed in contact with the pillar 30. In this case, a hole is also formed in the pillar 30 at a position corresponding to the hole h. The fixing member 24 is fixed to the pillar 30 by inserting a fixing tool such as a bolt into the hole h and fastening the fixing member 24 to the pillar 30 with a fastener such as a nut. The method of fixing the fixing member 24 to the pillar 30 is not limited to the above, and may be a method such as welding, or the above methods may be used in combination.

[0041] Second Embodiment Other embodiments of the present disclosure will be described below. Configurations similar to those in the first embodiment will be denoted by the same reference numerals and descriptions thereof may be omitted.

[0042] As shown in Fig. 6, the staircase 110 according to the second embodiment is a staircase in which both ends of the tread 10a are supported. The staircase 110 is an open-type staircase without risers. In the staircase 110, the tread 10a is fixed to a pair of left and right beams 31, 32. The beams 31, 32 are installed from the floor surface to the framework of the upper floor.

[0043] The step 10a is fixed to the beams 31 and 32 by a pair of receiving members 31a and 32a. The receiving members 31a and 32a protrude upward beyond the beams 31 and 32. Therefore, the step 10a is attached so as to float above the beams 31 and 32. The step 10a is formed to be wider than the distance between the beams 31 and 32, and both ends protrude outward from both beams 31 and 32.

[0044] The step 10a includes an FRP layer 11a and a buffer layer 12. The buffer layer 12 is arranged to cover at least a part of the lower surface of the FRP layer 11a. The configuration of the FRP layer 11a and the buffer layer 12 is not limited to the above, and the same configuration as that of the first embodiment can be adopted. However, since both sides of the step 10a are supported by the receiving members 31a and 32a, the FRP layer 11a can have a minimum thickness of 5 mm. With the above configuration, the staircase 110 can have a slim appearance. The buffer layer 12 can be arranged to cover the areas other than the areas where the receiving members 31a and 32a abut against the step 10a. The buffer layer 12 may be arranged at the areas where the receiving members 31a and 32a abut against the step 10a. In this case, for example, the buffer layer at the above areas can be crushed to the deformation limit, and then the receiving members 31a and 32a and the step 10a can be fixed.

[0045] Third Embodiment As shown in Fig. 7, the staircase 120 according to the third embodiment is a staircase in which the center of the tread 10b is supported. The staircase 120 is an open-type staircase without a riser. In the staircase 120, the tread 10b is fixed to a girder 33. The girder 33 is installed from the floor surface to the framework of the upper floor.

[0046] The step 10b is fixed to the beam 33 by a receiving member 33a. The receiving member 33a protrudes upward beyond the beam 33. Therefore, the step 10b is attached so as to float above the beam 33. The step 10b is formed to be wider than the beam 33, and both ends protrude to both outside of the beam 33.

[0047] The step board 10b includes an FRP layer 11b and a buffer layer 12. The buffer layer 12 is disposed so as to cover at least a portion of the lower surface of the FRP layer 11b. The configurations of the FRP layer 11b and the buffer layer 12 are not limited to those described above, and the same configuration as in the first embodiment can be adopted. However, the buffer layer 12 can be disposed so as to cover areas other than the area where the receiving material 33a contacts the step board 10b. The buffer layer 12 may be disposed at the area where the receiving material 33a contacts the step board 10b.

[0048] Fourth Embodiment As shown in Fig. 8, the staircase 130 according to the fourth embodiment is a staircase in which both end faces of the tread 10c are supported. The staircase 130 is an open-type staircase without risers. In the staircase 130, the tread 10c is fixed to a pair of side beams 34, 35 on the left and right. The side beams 34, 35 are installed from the floor surface to the framework of the upper floor.

[0049] Both end faces of the step plate 10c are fixed to a pair of side beams 34, 35. Therefore, the width of the step plate 10c and the distance between the pair of side beams 34, 35 are approximately the same.

[0050] The tread 10c comprises an FRP layer 11c and a buffer layer 12. The buffer layer 12 is arranged so as to cover at least a part of the underside of the FRP layer 11c. The configuration of the FRP layer 11c and the buffer layer 12 is not limited to the above, and the same configuration as in the first embodiment can be adopted. However, since both end faces of the tread 10c are supported by the side beams 34 and 35, the minimum thickness of the FRP layer 11c can be 5 mm. With the above configuration, a slim appearance of the staircase 130 can be achieved.

[0051] The configurations of the step boards 10a, 10b, and 10c according to the second, third, and fourth embodiments are not limited to those described above. The step boards 10a, 10b, and 10c may have the buffer layer 12 disposed on the side or corner of the step board, as in the first embodiment. The step boards 10a, 10b, and 10c may have a design layer, as in the first embodiment. When the step boards 10a, 10b, and 10c have a design layer, the design layer may cover only the lower surface side of the buffer layer 12. Or, the design layer may cover the entire surface of the buffer layer 12.

[0052] The staircase according to the embodiment of the present disclosure has been described above. However, the present disclosure is not limited to the above embodiment and can be modified as appropriate. [Explanation of symbols]

[0053] 100, 110, 120, 130 stages, 10, 10a, 10b, 10c pedals, 11, 11a, 11b, 11c FRP layers, 12, 12a, 12b, 12c buffer layers, 13 design layers, 21, 23a lower supports

Claims

1. An FRP layer made of fiber reinforced plastic; A staircase comprising a step having a cushioning layer arranged to cover at least a portion of the lower surface of the FRP layer and having a hardness lower than that of the FRP layer.

2. The staircase of claim 1 , wherein the FRP layer is made of carbon fiber reinforced plastic.

3. The steps according to claim 2, wherein the Young's modulus of the carbon fibers constituting the carbon fiber reinforced plastic is 500 GPa or more.

4. The steps according to claim 2 or 3, wherein the tensile strength of the carbon fibers constituting the carbon fiber reinforced plastic is 2000 MPa or more.

5. The staircase according to claim 2, wherein the thickness of the FRP layer is between 10 mm and 50 mm.

6. One end of the footboard is fixed to and supported by a frame, The staircase according to claim 5 , wherein the other end of the tread is not fixed to the main body.

7. 3. The staircase according to claim 1 or 2, wherein the buffer layer is integrally formed with the FRP layer.

8. The staircase according to claim 1 or 2, wherein the buffer layer is disposed so as to cover at least a portion of a side surface of the FRP layer.

9. The staircase according to claim 1 or 2, wherein the Shore A hardness of the buffer layer is 20 or more and 70 or less.

10. The staircase according to claim 1 or 2, wherein the buffer layer has an Asker C hardness of 20 or more and 90 or less.

11. The staircase according to claim 1 or 2, wherein the thickness of the buffer layer is between 5 mm and 50 mm.

12. The staircase according to claim 1 or 2, wherein the buffer layer is made of at least one of a resin, a cork, a hollow material, and a rubber material.

13. The staircase according to claim 1 or 2, wherein the step further comprises a decorative layer arranged to cover at least a portion of an outer surface side of the cushioning layer.

14. Further comprising a lower support tool that supports the footboard from below, The staircase according to claim 1 or 2, wherein the buffer layer is arranged to cover at least an area other than the area where the lower support contacts the tread.

15. 3. The staircase according to claim 1 or 2, which is an open staircase without risers.

16. A tread for use in the staircase according to claim 1 or 2.

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