JP4586046B2 - spiral staircase - Google Patents

Description

  The present invention relates to a spiral staircase.

  Conventionally, a spiral staircase may be constructed inside or outside a building. The spiral staircase is configured by spirally arranging a plurality of treads around a central column that is erected in the vertical direction, and each treadle is attached to the central column directly or via a bracket.

  By the way, the tread board and the bracket are attached to the central column with a predetermined interval in the height direction and shifted by a predetermined angle in plan view, so that positioning is very difficult, and in order to attach these accurately , It takes time and effort.

  Then, this invention makes it a subject to provide the spiral staircase with sufficient production and construction efficiency.

The present invention that solves such a problem is a spiral staircase that includes a center column that is erected in the vertical direction and a plurality of step plates that are spirally arranged around the center column. The support members that are supported by the support members that project from the support columns and are adjacent to each other in the height direction are connected to each other, and the support members include two radial frame members that project radially from the center support column. An outer peripheral node member connected to the distal end of each radial frame member, and an outer peripheral frame member connecting the distal end of each radial frame member via the outer peripheral node member, and a proximal end of each radial frame member A connecting end portion is formed on the portion, and a connecting groove into which the connecting end portion can be fitted is formed on the outer surface of the central support column.

  According to such a spiral staircase, the frame material and the central column can be connected simply by fitting the connecting end portion of the frame material to the connecting groove formed in the central column, so that the spiral staircase can be easily constructed.

  In addition, when the said center support | pillar is provided with the core pillar and the node member attached to the said core pillar, it is good to form the said connection groove | channel on the outer surface of the said node member.

  According to the spiral staircase according to the present invention, the production / construction efficiency is improved.

An embodiment of a spiral staircase according to the present invention will be described in detail with reference to the accompanying drawings.
Here, FIG. 1A is a plan view of a spiral staircase according to the present invention, FIG. 1B is a front view, FIG. 2 is an enlarged front view, FIG. 3 is an enlarged side view, and FIG. 5 is an exploded perspective view, FIG. 6A is a cross-sectional view of the central node member, FIG. 6B is an enlarged cross-sectional view of FIG. 6A, and FIG. 6C is a center spacer. 6 (d) is a cross-sectional view of the tread plate mounting plate, FIG. 6 (e) is a cross-sectional view of the fixed plate, FIG. 7 is a plan view of the support member, and FIG. 8 (a) is a view of the support member. FIG. 8 (b) is an exploded perspective view, FIG. 8 (b) is an enlarged perspective view for explaining a method of connecting the radial frame member (outer frame member) and the outer peripheral node member, and FIG. 9 (a) is a perspective view of the radial frame member (outer frame member). 9B is a side view of FIG. 10A, FIG. 10 is a plan view of a nodal member, FIG. 11 is an exploded perspective view of the handrail, and FIG. 12 is a side cross section of the handrail. It is.

As shown in FIG. 1, the spiral staircase according to the present invention includes a central column 10 that is erected in the vertical direction, a plurality of step plates 20 that are spirally arranged around the central column 10, and the step plate 20. The supporting member 30 is supported and a handrail 40 is configured. Further, as shown in FIGS. 2 to 4, the supporting members 30, 30 adjacent in the height direction are connected to each other at their tips.
In the present embodiment, as shown in FIG. 1, twelve steps (D1 to D12) are provided between the lower floor F1 and the upper floor F2, and the center strut 10 is extended from the lower floor F1. When the surroundings are viewed in plan and turn counterclockwise, the upper floor F2 is reached.
In the following description, “front side” and “back side” refer to the front side and the back side when facing the upward direction of the stairs, respectively.

(Center support)
As shown in FIGS. 1B and 2, the center column 10 is configured by alternately extrapolating a center node member (hereinafter referred to as a center hub 12) and a center spacer 13 to a core column 11. Further, in the present embodiment, as shown in FIG. 2, a tread plate mounting plate 14 is interposed on the upper surface of the central hub 12, and a fixing plate 15 is interposed on the lower surface.

  As shown in FIG. 4, the core column 11 is formed of a hollow extruded shape member made of an aluminum alloy with an outer peripheral shape formed into a regular polygonal cross section (in the figure, a regular dodecagon).

As shown in FIGS. 5 and 6A, the center hub 12 has a ring shape, and an inner periphery thereof is formed in a regular polygonal shape (a regular dodecagon in the figure) corresponding to the shape of the outer periphery of the core pillar 11. That is, the inner peripheral shape of the center hub 12 is the same as the outer peripheral shape of the core column 11. Moreover, the height dimension of the center hub 12 is made equal to the height dimension of the connection end part 31a (refer FIG. 9) of the radial frame material 31 mentioned later. Furthermore, the connection groove | channel 12a is formed in two places along the up-down direction in the outer surface of the center hub 12 (refer Fig.8 (a)).
The connecting groove 12a is formed in a shape in which a connecting end portion 31a (see FIG. 9) of a radial frame member 31 to be described later can be fitted, and as shown in FIG. Concavities and convexities that engage with the concavities and convexities of the connection end 31a of 31 are formed. As shown in FIG. 6A, when the central hub 12 is viewed in plan, the two connecting grooves 12a face the center of the central hub 12, and the central angle is 30 degrees.
The center hub 12 is made of an extruded shape made of an aluminum alloy, and the connecting groove 12a is formed when the aluminum alloy is extruded.

As shown in FIGS. 5 and 6C, the center spacer 13 has a ring shape, and protrusions 13a are formed on the inner surface thereof at a pitch of 120 degrees.
The protrusion 13 a has an abutting surface that abuts along a corner portion of the outer surface of the core column 11, and prevents the central spacer 13 from rotating.
The center spacer 13 is made of an extruded shape made of an aluminum alloy, and the protrusion 13a is formed when the aluminum alloy is extruded.
In the present embodiment, the cross-sectional shape of the central spacer 13 is a shape in which only the protrusion 13a abuts on the outer surface of the core column 11 in order to reduce the weight. However, the present invention is not limited to this. The ring portion may be dense.

As shown in FIGS. 5 and 6 (d), the tread board mounting plate 14 is a ring-shaped plate material whose inner peripheral shape is the same as the outer peripheral shape of the core pillar 11. A mounting portion 14a is formed on the outer periphery of the tread plate mounting plate 14 so as to protrude outward.
As shown in FIG. 5 and FIG. 6E, the fixed plate 15 is a ring-shaped plate material whose inner peripheral shape is the same as the outer peripheral shape of the core column 11.

  Further, as shown in FIG. 1 (b), a lower center having the same cross-sectional shape as the central spacer 13 is provided below the central hub 12 of the first stage D1 and above the central hub 12 of the twelfth stage D12. A spacer 13 </ b> A and an upper center spacer 13 </ b> B are extrapolated to the core pillar 11.

(Tread board)
The tread board 20 is made of a plate material made of wood or metal, and is formed in a substantially fan shape as shown in FIGS. Further, as shown in FIG. 5, bolt insertion holes 20a, 20a are formed on the distal end side of the tread plate 20, and bolt insertion holes 20b are formed on the proximal end side. In this embodiment, the base end side of the tread plate 20 is supported and fixed to the mounting portion 14a of the tread plate mounting plate 14, and the distal end side is supported and fixed to the node members 33 and 34 via a fixing ring 36 described later.

(Support member)
As shown in FIGS. 5 and 7, the support member 30 is connected to two radial frame members 31, 31 projecting radially from the central column 10 (central hub 12), and the distal ends of the radial frame members 31. It is comprised from the outer periphery node members 33 and 34 and the outer periphery frame material 32 which connects the radial frame materials 31 and 31 via the outer periphery node members 33 and 34. FIG.

  Hereinafter, the outer peripheral node member 33 is referred to as an “outer peripheral hub 33”, and the outer peripheral node member 34 is referred to as an “outer peripheral eyeglass hub 34”. In this embodiment, the outer peripheral hub 33 is connected to the radial frame member 31 located on the back side (right side in FIG. 5) of each step, and the outer peripheral eyeglass hub 34 is connected to the radial frame member 31 located on the near side. However, these may be arranged in the reverse order of the illustrated case.

The radial frame member 31 is obtained by processing a hollow extruded shape member made of an aluminum alloy having a circular cross section, and has flat connection end portions 31a at both ends thereof as shown in FIGS. 9 (a) and 9 (b). ing. Further, an unevenness is formed at the tip of the connection end 31 a in a direction orthogonal to the axis of the radial frame material 31.
The connection end portion 31a is formed by crushing both ends of the hollow extruded shape member by pressing or the like. The connection end 31a is formed in a flat shape that is long in the axial direction (vertical direction) of the outer peripheral hub 33 and the outer spectacle hub 34 (see FIG. 8B). A strong joint structure is formed against an external force in the axial direction (vertical direction).

  Similar to the radial frame material 31, the outer peripheral frame material 32 is obtained by processing a hollow extruded profile made of an aluminum alloy having a circular cross section, and has flat connection end portions 32a at both ends thereof (FIG. 9). reference). Since other configurations are the same as those of the radial frame member 31, detailed description thereof is omitted.

As shown in FIG. 8, the outer peripheral hub 33 is formed in a cylindrical shape, and a plurality of connecting grooves 33 a are formed on the outer surface along the axial direction (vertical direction) of the outer peripheral hub 33. A coupling insertion hole 33b is formed in the center of the outer peripheral hub 33 along the axial direction (vertical direction).
As shown in FIG. 10A, the connecting groove 33a is formed in a shape in which the connecting end 31a of the radial frame member 31 and the connecting end 32a of the outer peripheral frame member 32 can be fitted. Concavities and convexities that engage with the concavities and convexities of the connecting end 31a (32a) are formed. In the present embodiment, the three connecting grooves 33a are formed at intervals of 75 degrees.
The outer peripheral hub 33 is made of an extruded shape made of an aluminum alloy, and the connecting groove 33a is formed when the aluminum alloy is extruded.

When the radial frame member 31 is connected to the outer peripheral hub 33, the connecting end portion 31a of the radial frame member 31 is connected to the connecting groove 33a from the upper surface side (or lower surface side) of the outer peripheral hub 33 as shown in FIG. Can be fitted (inserted). Then, as shown in FIG. 10A, the unevenness formed in each of the connection groove 33a and the connection end portion 31a is engaged with each other, so that the radial frame material 31 is not pulled out in the axial direction. The same applies when the outer peripheral frame member 32 is connected to the outer peripheral hub 33.
In addition, as shown in FIG. 8, a groove filling member 39 having the same size and shape as the connection groove 33a is provided in the connection groove 33a to which neither the radial frame material 31 nor the outer peripheral frame material 32 is connected. Fit (insert). Or you may use the outer periphery hub (not shown) which formed the connection groove | channel 33a only in the site | part to which the radial frame material 31 and the outer periphery frame material 32 are connected.
Further, if a connecting groove is formed as in the present embodiment, it can also be used as it is for a spiral staircase in the opposite direction (clockwise) to the present embodiment.

  The outer peripheral eyeglass hub 34 is made of an extruded shape made of an aluminum alloy, and as shown in FIG. 8A, a connecting insertion hole 34b and a handrail insertion hole 34c are formed along the axial direction (vertical direction). . A plurality of connecting grooves 34a are formed along the axial direction (vertical direction) of the outer peripheral eyeglass hub 34 on the outer surface of the outer peripheral eyeglass hub 34 and around the connecting insertion hole 34b. Since the structure of the connection groove 34a is the same as that of the connection groove 33a of the outer peripheral hub 33 described above, detailed description thereof is omitted.

  When the radial frame member 31 is connected to the outer peripheral eyeglass hub 34, the connection end 31a of the radial frame member 31 may be fitted into the connecting groove 34a from the upper surface side (or lower surface side) of the outer peripheral hub 34. Then, as shown in FIG. 10B, the concave and convex portions formed in each of the connecting groove 34a and the connecting end portion 31a engage with each other, so that the radial frame material 31 is not pulled out in the axial direction. The same applies when the outer peripheral frame member 32 is connected to the outer peripheral eyeglass hub 34.

  As shown in FIGS. 2 and 5, a fixing ring 36 having the same thickness as the tread plate mounting plate 14 of the center column 10 is attached to the upper surfaces of the outer peripheral hub 33 and the outer spectacle hub 34. An outer periphery spacer 35 is interposed between the tread plate 20 and the tread plate 20. A lower fixing ring 37 is attached to the lower surface of the outer peripheral hub 33 to prevent the radial frame member 31 and the outer peripheral frame member 32 from being pulled out downward. In addition, although illustration is abbreviate | omitted, the outer periphery spectacle hub 34 may be lengthened and the outer periphery spacer 35 may be abbreviate | omitted.

  Further, as shown in FIGS. 2 to 5, the support members 30, 30 adjacent in the height direction are connected by a bolt B <b> 1 inserted from the upper surface of the upper tread 20 to the outer peripheral hub 33 of the lower support member 30. ing.

(handrail)
The handrail 40 is made of a bar material made of wood or metal, but the shape, size, length, etc. of the cross section can be appropriately set according to the configuration of the spiral staircase. In the present embodiment, as shown in FIG. 11, the hollow member having a substantially semicircular cross section is fixed to the handrail support column 41 via the handrail mounting bracket 42.

  The handrail support column 41 is made of a hollow extruded shape member made of an aluminum alloy having a circular cross section, and has screw holes 41a and 41b formed at the upper and lower ends as shown in FIG.

  As shown in FIG. 11, the handrail mounting bracket 42 is formed by bending a plate made of aluminum alloy, has mounting surfaces 42b and 42b inclined at a step gradient at both ends, and has a bolt insertion hole 42a at the center. ing.

(Spiral staircase construction procedure)
Next, the construction procedure of the spiral staircase according to the present invention will be described with reference to the attached drawings.

First, the core column 11 (see FIG. 4) of the center column 10 is erected on the soil concrete G, and the lower center spacer 13A is extrapolated from above. Next, the first stage D1 to the twelfth stage D12 are constructed in sequence, but the construction procedure of each stage is the same, so as an example, the tenth stage D10 is constructed on the ninth stage D9 shown in FIG. This will be described with reference to FIG. In the following description, members constituting the tenth stage D10 are shown unless otherwise specified.
In addition, when installing a spiral staircase on two or more floors, the core pillar 11 is erected on the floor slab.

  As shown in FIG. 5, the center hub 12 to which the center spacer 13, the fixing plate 15, and the support member 30 are attached is sequentially extrapolated to the core column 11. In addition, although illustration is abbreviate | omitted, the center spacer 13 will be mounted on the tread board attachment plate 14 of the 9th step | paragraph D9 shown in FIG.

  At this time, since the outer periphery of the core pillar 11 and the inner periphery of the central hub 12 each have a regular polygonal cross section, the central hub 12 does not rotate in the circumferential direction. That is, the center hub 12 is positioned only by extrapolating the center hub 12 to the core column 11, and the direction of the connecting groove 12a is accurately determined. In this embodiment, since the outer periphery of the core pillar 11 and the inner periphery of the center hub 12 are regular dodecagons, the direction of the connecting groove 12a of the center hub 12 can be adjusted in steps of 30 degrees.

  Further, the center hub 12 is extrapolated so that the connection groove 12a is shifted from the connection groove 12a of the center hub 12 of the ninth stage D9 by a predetermined angle (30 degrees in this embodiment). Therefore, the radial frame material 31 positioned on the front side of the support member 30 projects in the same direction as the radial frame material 31 positioned on the back side of the support member 30 of the ninth stage D9 in plan view.

  Here, as shown in FIG. 8A, the support member 30 is formed of the radial frame material 31 located on the back side (right side in FIG. 8A) of the two radial frame materials 31 and 31. The connecting end portion 31a on the distal end side is fitted (inserted) into the connecting groove 33a of the outer peripheral hub 33, and the connecting end portion 31a on the front end side of the radial frame member 31 located on the near side is connected to the connecting groove 34a of the outer peripheral eyeglass hub 34. Further, the connecting end portions 32a and 32a of the outer peripheral frame member 32 are fitted into the connection grooves 33a and 34a of the outer peripheral hub 33 and the outer spectacle hub 34, respectively. Therefore, no special tool or welding is required when assembling the support member 30.

  Further, the support member 30 is fixed to the central column 10 by fitting the connection end portion 31 a on the proximal end side of each radial frame member 31 into the connecting groove 12 a of the central hub 12.

  Next, as shown in FIG. 5, the tread plate mounting plate 14 is extrapolated to the core column 11 so that the mounting portion 14 a is positioned above the connecting groove 12 a of the center hub 12. Further, the fixing ring 36 is placed on the upper surface of the outer peripheral hub 33 and the upper surface of the outer peripheral eyeglass hub 34, respectively.

  Next, the tread plate 20 is placed on the upper surface of the mounting portion 14 a of the tread plate mounting plate 14 and the upper surfaces of the fixing rings 36, 36, and the outer peripheral spacer 35 is interposed on the lower surface of the outer spectacle hub 34.

  Then, from the upper side of the tread plate 20, the bolt B1 is inserted into the insertion holes of the fixing ring 36, the outer peripheral eyeglass hub 34, the outer peripheral spacer 35, the step plate 20 of the ninth stage D9, the fixing ring 36, the outer peripheral hub 33 and the lower fixing ring 37, The support member 30 of the ninth stage D9 and the support member 30 of the tenth stage D10 are connected.

  When the support members 30 and 30 adjacent to each other in the height direction are connected to each other in this way, for example, in the case of FIGS. 3 and 4, the load acting on the tread plate 20 of the seventh stage D7 is supported by the eighth stage D8. The member 30 and the support member 30 of the sixth stage D6 are also dispersed, that is, the load acting on the tread 20 of the seventh stage D7 is not resisted only by the support member 30 of the seventh stage D7, As a result, the supporting member 30 can be lightened.

  Further, as shown in FIG. 5, the tread plate 20 is fixed to the outer peripheral hub 33 and the outer spectacle hub 34 by a bolt B1, and the base end side is fixed to the tread plate mounting plate 14 by a bolt B1 '.

Next, as shown in FIG. 5, the screw rod B <b> 2 is attached to the screw hole 41 a of the handrail support column 41, and the screw rod B <b> 2 is inserted into the handrail insertion hole 34 c of the outer peripheral eyeglass hub 34. Then, the screw rod B <b> 2 protruding from the lower surface of the outer spectacle hub 34 is screwed into the screw hole 38 a (see FIG. 12) of the cap nut 38, and the handrail column 41 is fixed to the outer spectacle hub 34.
Thus, the outer peripheral eyeglass hub 34 is provided with the handrail insertion hole 34c for attaching the handrail post 41, so that the handrail post 41 can be easily attached.

  Finally, as shown in FIG. 11, the handrail mounting bracket 42 is attached to the upper end of the handrail support column 41, the lower surface of the handrail 40 is brought into contact with the mounting surface 42b of the handrail mounting bracket 42, and fixed with the bolt B4. As shown in FIG. 12, the notch 40 a provided on the lower surface of the handrail 40 prevents the head of the bolt B <b> 4 from coming into contact with the lower surface of the handrail 40.

  As described above, according to the spiral staircase according to the present embodiment, since the support member 30 that supports the tread plate 20 is configured by the radial frame material 31 and the outer peripheral frame material 32, the spiral staircase becomes light and open. That is, even if the spiral staircase according to the present embodiment is constructed indoors, it is light, and therefore it is possible to create a bright indoor space without a feeling of pressure.

  Further, when adjusting the height of the kick-up or the installation height of each step, it is only necessary to change the height dimension of the outer peripheral spacer 35 attached to the lower surface of the central spacer 13 and the outer spectacles hub 34 that is extrapolated to the core pillar 11. Alternatively, a height adjusting spacer (not shown) may be extrapolated to the core column 11. In any case, it is possible to easily cope with the installation conditions (the number of steps, the height of the lift, etc.) of the spiral staircase that is different for each building, and fine adjustment at the construction site is also easy. That is, even if the installation conditions of the spiral staircase are different, the central hub 12, the radial frame member 31, the outer peripheral frame member 32, the outer peripheral hub 33, and the outer spectacle hub 34 should be used in common without changing their dimensions and shapes. It is suitable for mass production and has high production efficiency.

  In addition, by making each member constituting the central support column 10 and each member constituting the support member 30 made of an aluminum alloy, it is lighter in strength and takes advantage of the aluminum alloy that it is difficult to corrode, and has a lighter structure. You can build a spiral staircase.

  In addition, the construction procedure of the spiral staircase is not limited to the construction procedure described above, and may be appropriately changed according to the construction conditions. For example, the support member 30 (radial frames 31, 31) may be connected after the center hub 12 is extrapolated to the core pillar 11, or the tread board mounting plate 14 and the tread board 20 are integrated in advance. Also good.

(Modification 1)
In the above-described embodiment, the outer peripheral shape of the core pillar 11 and the inner peripheral shape of the central hub 12 in the central support column 10 are regular polygons. However, the present invention is not limited to this, for example, the center shown in FIG. A plurality of engaging pieces 71 a are formed on the outer periphery of the core column 71 like the support column 70, and an engaging piece 72 b that is engaged with the engaging piece 71 a of the core column 71 is formed on the inner periphery of the center hub 72. But you can.
According to the center column 70 having such a configuration, when the center hub 72 is extrapolated to the core column 71, the engagement piece 71a of the core column 71 and the engagement piece 72b of the center hub 72 are engaged. The hub 72 does not rotate in the circumferential direction. That is, the center hub 72 is positioned only by extrapolating the center hub 72 to the core column 71, and the direction of the connecting groove 72a is accurately determined.

(Modification 2)
In the above embodiment, the radial frame member 31 and the outer peripheral frame member 32 are circular in cross section, but the present invention is not limited to this, and the radial frame member 51 (outer peripheral frame member 52) shown in FIG. Thus, it may be a rectangle.

Here, the radial frame material 51 (outer frame material 52) is obtained by processing a hollow extruded shape made of an aluminum alloy having a square cross section, and is flattened at both ends as shown in FIGS. 14 (a) and 14 (b). The connection end 51a has a shape. Further, an unevenness is formed at the tip of the connection end 51 a in a direction perpendicular to the axis of the radial frame material 51.
The connection end portion 51a is formed by crushing both ends of a hollow extruded shape having a square cross section shown in FIG. 14C by pressing or the like, but after crushing two opposing sides out of the four sides, (See FIG. 14 (d)), and the remaining two sides are crushed (see FIG. 14 (e)) to form the connection end 51a. Therefore, the height of the connection end 51a is the height of the hollow extruded shape. It does not spread beyond the dimensions.

  And if the supporting member 50 is comprised using the radial frame material 51 and the outer periphery frame material 52, as shown in FIG. 15, it will be possible to mount the tread board 20 directly over the full length of the radial frame material 51. In addition, although not shown, the tread plate 20 can be placed directly on the upper surface of the outer peripheral frame member 52, so that bending / deformation of the tread plate 20 can be suppressed.

  Further, since the treads can be placed directly on the upper surfaces of the radial frame member 51 and the outer peripheral frame member 52, the tread plate mounting plate 14 and the fixing ring 36 shown in FIG. 5 are not required, and the number of parts can be reduced.

(A) is a top view of the spiral staircase based on this invention, (b) is a front view similarly. It is an enlarged front view of the spiral staircase which concerns on this invention. It is an expansion side view of the spiral staircase which concerns on this invention. It is an expansion perspective view of the spiral staircase which concerns on this invention. It is a disassembled perspective view of the spiral staircase which concerns on this invention. (A) is a cross-sectional view of the central node member, (b) is an enlarged cross-sectional view of (a), (c) is a cross-sectional view of the center spacer, (d) is a cross-sectional view of the tread plate mounting plate, (e ) Is a cross-sectional view of the fixed plate. It is a top view of a supporting member. (A) is an exploded perspective view of a support member, (b) is an enlarged perspective view for explaining a method of connecting a radial frame member (outer peripheral frame member) and an outer peripheral node member. (A) is a perspective view of a radial frame material (peripheral frame material), (b) is a side view of (a). It is a top view of an outer periphery node member. It is a disassembled perspective view of a handrail. It is a side sectional view similarly. It is a top view which shows the other example of the member which comprises a center support | pillar. (A) is a perspective view showing another example of a radial frame material (outer frame material), (b) is a side view of (a), and (c), (d) and (e) are radial frame materials (outer frame material). It is sectional drawing which shows the processing method of this connection edge part. It is an enlarged front view at the time of comprising a supporting member with the radial frame shown in FIG.

Explanation of symbols

10 Center column 11 Core column 12 Center hub (Center node member)
12a Connecting groove 13 Center spacer 20 Tread 30 Support member 31 Radial frame member 31a Connection end 32 Outer frame member 33 Outer hub (outer peripheral node member)
33a Connecting groove 34 Outer peripheral eyeglass hub (outer peripheral node member)
34a Connection groove 34b Connection insertion hole 34c Handrail insertion hole 35 Peripheral spacer 40 Handrail 41 Handrail support

Claims (2)

In a spiral staircase comprising a central column erecting in the vertical direction and a plurality of treads arranged in a spiral around the central column, the tread is supported by a support member protruding from the central column , The supporting members adjacent in the vertical direction are connected to each other, and the supporting member is connected to two radial frame members projecting radially from the central support column and to the distal ends of the radial frame members. An outer peripheral node member and an outer peripheral frame member that connects the distal ends of the respective radial frame members via the outer peripheral node member, and a connection end is formed at a base end portion of each of the radial frame members. The spiral staircase is characterized in that a connecting groove into which the connecting end can be fitted is formed on the outer surface of the central support column. The said center support | pillar is comprised including the core pillar and the nodal member attached to the said core pillar, The said connection groove | channel is formed in the outer surface of the said nodal member. The described spiral staircase.

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