JP2024070376A - Unit construction of spiral staircase and assembly method for spiral staircase - Google Patents

Abstract

To solve the problem in which, in a conventional helical staircase with a girder structure, mounting accuracy of stair treads is difficult to secure and assembly checking cannot be conducted in a factory in advance, leading to instable quality.SOLUTION: A unit construction of a helical staircase with a girder structure is constituted with multiple stair tread members comprising a horizontal member with a tread at its upper side and one or more vertical members coupling vertically below the horizontal member, and helical multiple lines of plates. The multiple lines of plates are fixed to face side end faces of the vertical members and lower sides of the horizontal members respectively of the stair tread members after helically placing the stair tread members with temporary support materials and then constitute a helix by detaching the temporary support materials.SELECTED DRAWING: Figure 11

Description

The present invention relates to a unit structure of "helical staircases with girder structure" and an assembly method thereof.
The subject of this invention is "spiral staircases with girder structure" and does not include steps made of bricks, marble, etc. Also, even if it is Stairs, it does not include "staircases in which the outer edge of the steps is directly attached to the wall" or "spiral staircases in which the inner edge of the steps is attached to the outer periphery of the support" that are not girder structure.

The background technology of the present invention will be explained below in the following order: "Classification and structure," "Historical background," and "Technical background" of "Direct staircases with girder structure" and "Helical staircases with girder structure."

The classification and configuration of the "straight staircase with girder structure" is shown below with reference to Figure 33.
- "Straight stairs with girder structure" include "force girder stairs 1" and "side girder stairs 2".
- The materials used for the "Strength Beam Stairs 1" and "Side Beam Stairs 2" include steel, wood, and reinforced concrete (RC).
The "force girder staircase 1" is composed of one or more rows of force girders 4 and a step plate 20 fixed horizontally to the upper side thereof.
- The "side girder staircase 2" is composed of two side girders 5 made of plate material and a step plate 20 fixed horizontally at the narrow end of the side girders.
- Depending on the design, the "force girder stairs 1" and "side girder stairs 2" may have force girders 4 and side girders 5 in the form of jagged stringers 6, which are called "stringer stairs 3".

The historical background of the "straight staircase with girder structure" is as follows:
The dawn of the "straight staircase with girder structure" can be found at the Toro ruins from the Yayoi period, about 2000 years ago. Primitive log ladders, which were carved into logs and used as footholds, were used in stilt houses. It is believed that this developed into the "straddle staircase 1."
- After the Industrial Revolution, which took place from the mid-18th century through to the 19th century, when steel frame technology became widespread, steel "strength girder stairs" and "side girder stairs" became widely used both indoors and outdoors as their production became mechanized and their construction became unitized.
・RC models seem to have become popular after the 19th century.

First, the "technical background" of the "straight staircase with girder structure" is described below.
- "Force girder stairs" and "side girder stairs" use "girders" and "plates" respectively that have a certain rigidity and are placed diagonally in the direction of travel to secure the steps.
- The difference is that the "girders" of a "force girder staircase" have a "girder-shaped cross-section" of one or more rows, while the "plates" of a "side girder staircase" have a "plate-shaped cross-section" of two rows.

Next, the "classification and configuration" of "spiral staircases with girder structures" is shown below.
・There are two types of "spiral staircases with girder structures": "spiral staircases with side girder stairs" and "spiral staircases with box sections." There are few examples of "spiral staircases with force girder stairs." The reason for this is that it is difficult to process the girder material that will become the force girder into a spiral.
- A "spiral staircase with side beams" is made up of two spiral boards and a narrow, horizontally fixed step, and is available in steel or wood.
・"Box section spiral staircases" are made of a box section consisting of stringers, steps, and a bottom board, and are made of either "hollow wood" or "solid reinforced concrete." There are no examples of "hollow steel" staircases. The reason is that it is difficult to form a box section into a spiral.
- In the case of "spiral staircases with stringer stairs" and "box-section spiral staircases", depending on the design, the parts that correspond to the stringers may have jagged stringer shapes.

The historical background of the "spiral staircase with girder structure" is given below.
- Iron and wooden spiral staircases with side beams became popular both domestically and internationally with the development of civilian technology after World War II.
- It seems that the spiral staircases with side girders made of iron and wood could not have been made without the development of civilian technologies after World War II, such as spiral processing technology for steel plates or woodworking technology using plywood processing and power tools.
・At the dawn of the Middle Ages, "beam-structured spiral staircases" could only be made of "hollow wood" and "box-section spiral staircases." A rare example from the early days is the famous "St. Joseph's Wooden Spiral Staircase at the Loretto Chapel in Santa Fe," built in the mid-18th century before the Industrial Revolution. However, in modern times, the technology to make "hollow wood" and "box-section spiral staircases" has fallen into disuse.
- "Box-section spiral staircases" made of "solid reinforced concrete" are becoming more and more common in high-end homes made of reinforced concrete in the People's Republic of China these days.
In short, the history of "girder-structured spiral staircases" begins with the "hollow wooden""box-section spiral staircase" before the Industrial Revolution, which then fell out of use, and with the development of civilian technology after World War II, "iron" or "wooden""spiral staircases with side girder stairs" or "solid reinforced concrete""box-section spiral staircases" were developed, and continue to the present day.

Next, the "technical background" of the "spiral staircase with girder structure" is presented below.
・A "wooden""spiral staircase with stringers" can be made by bending the stringers into a spiral shape using power tools on a "full-size cylindrical temporary frame" and gluing thin boards in order into a spiral shape, then processing them into plywood. However, this method is not common because it requires a specialized woodworker, and requires a lot of work, which increases the construction time and costs.
- A "wooden""strength girder spiral staircase" is even more difficult to bend into a spiral the wooden beams that serve as the strength beams than a "strength girder spiral staircase," and no examples have been seen of this.

- A "steel""spiral staircase with side beams" can be manufactured by rolling rectangular steel plates into a spiral in a factory, during which the steel plates that will become the side beams are bent into a spiral. Here, the step plates can be cut with high precision to form single curves of different curvatures in plan view at both edges where they connect to the steel plates that will become the side beams. However, the surface precision of the steel plates that will become the two rows of side beams that draw different spirals of different sizes that are rolled cannot be achieved. For this reason, the joint surfaces of the two do not easily match, and the quality and precision are not stable.
・The force beams of the "spiral staircase with force beams" made of steel are usually made of shaped steel. Conventionally, in terms of machinery and equipment, rolling into a spiral is possible with steel plates and small diameter steel pipes, but with shaped steel, it is generally not possible. Therefore, it is difficult to manufacture a "spiral staircase with force beams" made of steel.

・Whether the "spiral staircase with stringer stairs" is made of "wood" or "iron", two rows of stringers are fixed to the upper and lower floors, and then the steps are attached in order. Therefore, the two cannot be rigidly connected to each other structurally, which creates a structural weakness.
・In addition, a large torsional moment occurs at the fixing points of the two stringers to the floor above and below, which become weak points in the structure. This makes the quality of the structure unstable and reduces the durability overall.

・The Gothic-style St. Joseph's Spiral Staircase at the Loretto Chapel in Santa Fe, from the mid-18th century before the Industrial Revolution, is a rare example of a hollow wooden box-section spiral staircase from the early days of girder-structure spiral staircases. It has a height difference of about 7m and spirals in a coil shape of 720 degrees (2 revolutions).
-It is believed that the "St. Joseph's Spiral Staircase" could have been created by connecting each piece of box cross-section in a spiral on a "full-scale cylindrical template."
- The St. Joseph's Spiral Staircase's box cross-section formed by the steps, two rows of stringers, and base plate increases the second moment of area and spring constant, and the precise joinery using very hard types of wood increases the Young's modulus and spring constant, contributing to reduced deformation and improved durability.
-Today, hollow wooden box-section spiral staircases, such as the elegant Gothic St. Joseph's Spiral Staircase, depend on the skill of the craftsman, so the production techniques have fallen into disuse.

On the other hand, the number of examples of "box-section spiral staircases" made of "solid reinforced concrete" has been increasing recently, especially in high-end houses made of reinforced concrete (RC) in the People's Republic of China.
・The construction of a "box-section spiral staircase" made of "solid reinforced concrete" involves first assembling the bottom formwork and formwork supports on the spiral, then assembling the reinforced concrete in a lattice pattern, attaching the side formwork and riser formwork, and pouring the cast-in-place concrete. After that, after a curing period, the staircase hardens, and is then demolded and decorated. This requires a significant amount of man-hours and construction time.
- The "box-section spiral staircase" made of "solid reinforced concrete" is highly rigid, but vulnerable to tensile deformation, and cannot be applied to the "St. Joseph's Spiral Staircase" which spirals in a coil shape with 720 degrees (2 turns). Although it does not shake much, it is extremely vulnerable to earthquakes and deformation and distortion of the building itself.

The present invention provides a unit structure and assembly method for "helical staircases with girder structure" that are excellent for interior design, have a highly rational structure, and are easy to manufacture.

JP 2002-206320 A

The above describes the background technology of conventional straight and spiral staircases with girder structure. Based on the above, the problems regarding the unit structure and assembly method of the "spiral staircase with girder structure" that the present invention aims to solve are summarized as follows: 1) to 17).
1) "Spiral staircase with stringer stairs" is cut and processed with a single curve with different curvatures in plan view at both ends of the stringer side of the step board. On the other hand, the precision of rolling the stringers that draw two rows of spirals with different sizes is not achieved. For this reason, the joint surfaces of the two do not easily match, which becomes a structural weakness.
2) A large torsional moment occurs at the fixing points of the two stringers to the floor at the top and bottom, which become weak points in the structure, making the quality of the structure unstable and reducing the durability overall.
3) In the "spiral staircase with side beams," the plate material, which is difficult to fix and has poor manufacturing precision, is fixed first, and then the steps are attached to it. This makes it inefficient and inaccurate, and because of the structure based on this procedure, the two cannot be rigidly connected together, resulting in unstable quality and precision.
4) The "steel""spiral staircase with side beams" is vulnerable to torsional deformation because the side beams do not have flanges, so they must be made extremely thick and firmly connected to the upper and lower floors. This makes the structure less rational and increases the installation costs.
5) In the case of a "steel""spiral staircase with side beams," if the side beam is a single long piece, the processing precision into the spiral is reduced, and transportation and erection are costly. On the other hand, if it is divided, the joints become weak points in the girder structure, causing shaking and reducing durability.
6) Although the “spiral staircase with stringer stairs” is a beautiful structural form with a skeleton, a rational unit structure and assembly method have not yet been found.

7) A "spiral staircase with braced beams" can be made by using power tools to process the braced beams of wood, by gluing thin boards in a spiral pattern in order using glue on a "cylindrical, full-size temporary frame," and then processing the boards into plywood. However, processing plywood makes the process complicated and expensive.
8) The force beams of the "spiral staircase with force beams" made of iron are usually made of steel sections. Conventionally, in terms of rolling into a spiral, the processing that is possible with steel plates and small diameter steel pipes is generally not possible with steel sections due to the machinery and equipment. Therefore, it is difficult to manufacture "spiral staircase with force beams" made of iron.
9) Therefore, although the “spiral staircase with braced girders” is a structural form that excels in functional beauty, a rational unit structure and assembly method have not yet been found.

10) Wooden box-section spiral staircases, such as the elegant Gothic St. Joseph's Staircase from the mid-18th century, rely on the skill of artisans, so the technology for making them has fallen into disuse and they can no longer be made today.

11) The "box-section spiral staircase" made of "solid reinforced concrete" is made of reinforced concrete, which is vulnerable to deformation, so although it does not shake much, it is extremely vulnerable to earthquakes and deformation and distortion of the building itself.
12) A "box-section spiral staircase" made of "solid reinforced concrete" is vulnerable to deformation, so it can only spiral at most 270 degrees, and cannot be used for the "St. Joseph's Spiral Staircase," which spirals at 720 degrees (2 revolutions) in a coil shape.
13) The construction of a "box-section spiral staircase" made of "solid reinforced concrete" involves first assembling the bottom formwork and formwork supports on the spiral, then assembling the reinforcing bars in a lattice pattern, attaching the side formwork and riser formwork, and pouring the cast-in-place concrete. After the curing period, the staircase is removed and decorated. This means that the construction period is extremely long.

14) In the past, side girder stairs were generally limited to a spiral or straight line shape due to the manufacturing and assembly of the side girders, and could not accommodate a combination of both. When placing a spiral staircase on the wall side of a house, a combination of both lines is unavoidable due to space limitations, but to realize this structure, generally there is no other way than to use "dense reinforced concrete" which takes a long time to construct, and is not very convenient.

15) Regardless of the structural style of the "spiral staircase with girder structure," it is difficult to perform assembly inspections in advance at the factory, which leads to trial and error on-site and unstable quality. Even if assembly inspections were performed at the factory, it would be difficult to disassemble and reassemble all the parts, so the staircase would have to be transported in one piece, which would incur transportation costs.

16) Generally, "beam-structured spiral staircases" have two rows of boards that, due to the geometrical properties of a spiral, form a single curve with varying curvature in plan view and draw different spirals as a whole, with each row having its own side perpendicular to the line of intersection with the vertical plane radiating from the center of the spiral and spaced apart at equal intervals, yet the steps are haphazardly fixed into the narrow space between the two rows of boards. Therefore, the geometrical properties of the spiral are not utilized in the shape of the steps or in the fixing of the steps to the boards, resulting in a fragile structure.
17) In the first place, almost all of the prior art for spiral staircases, including Patent Document 1, is related to "spiral staircases in which the inner edge of the step plate is assembled to the outer periphery of the support pillars," and there are almost no "spiral staircases with girder structures." Therefore, at present, the issues regarding the unit structure and assembly method of "spiral staircases with girder structures" have not been fully resolved.

In order to solve the above problems, the first aspect of the present invention is a unit structure for a spiral staircase, which is composed of multiple step members consisting of a horizontal member with a tread on the upper side and one or more vertical members connected vertically to the lower side of the horizontal member, and multiple rows of plate materials, the multiple step members are arranged in a spiral as a whole with each of their horizontal members horizontal and their vertical members vertical, the multiple rows of plate materials are arranged in a spiral as a whole with their sides approximately vertical, and at least two or more rows of the multiple rows of plate materials are fixed facing either side end face of the vertical member and the lower edge of the horizontal member.

In order to solve the above problem, the second aspect of the present invention is a method for assembling a spiral staircase with a modular structure, which comprises the steps of: preparing multiple step members and multiple rows of plate materials, each consisting of a horizontal member with a tread on the upper side and one or more vertical members connected vertically to the lower side of the horizontal member; and arranging the multiple step members in a spiral shape as a whole by fixing the vertical members of the multiple step members vertically and the horizontal members horizontally to multiple temporary support members that are previously erected in an arc shape on a base surface; fixing at least two or more rows of the multiple rows of plate materials facing either side end face of the vertical member and the lower edge of the horizontal member to form a spiral as a whole; and detaching the multiple temporary support members from the multiple step members.

The unit structure of the spiral staircase according to the first aspect of the present invention can achieve the following effects 1) to 6) when applied to a "spiral staircase with a girder structure."

1) A step member made up of a horizontal member and a vertical member has at least two or more rows of board materials arranged in a spiral, bound to one of the side end faces of the vertical member and pressed down and fixed to the lower edge of the horizontal member. Here, the only thing that geometrically allows the insertion of a member to bind the two rows of board materials in a straight line is the narrowness of the vertical plane radiating from the center of the spiral. The vertical member of the step member matches this. For this reason, the step member secures the two rows of board materials precisely and efficiently, like joinery.

2) In the past, whether made of steel or wood, "spiral staircases with side beams" had structural weaknesses because the steps could not be attached to the side beams accurately and could not be fully joined. However, with this invention, the step members do not require curved processing, and two rows of plate members can be joined in a straight line with high precision and efficiency.

3) The multiple step plate members are composed of horizontal members aligned horizontally and radially from the spiral center, and vertical members joined vertically downward to the horizontal members and aligned vertically and radially from the spiral center. The multiple rows of plate members are then fixed lengthwise and widthwise, facing the side end faces of the vertical members and the bottom edges of the horizontal members. This allows the multiple rows of plate members to be straightened into the specified spiral.

4) Horizontal members with treads on the upper side may have the treads as an integral part or as separate parts. In the former case, the horizontal members can be made inexpensively by cutting them into a fan shape with the wide flange surface on the tread side as flat angle steel material. In the latter case, the tread material can be selected depending on the application, such as grating or checkered steel plate, which increases the freedom of design.

5) Conventionally, "steel" "spiral staircases with side girder steps" have two rows of side girders that are weak against torsional deformation and are therefore extremely thick, which increases the costs of processing the spiral and installation. However, with this invention, the vertical members restrain the plate members arranged in the spiral in two rows on their own side end faces, both vertically and horizontally in the bridge axis (longitudinal) direction and the transverse direction, making them resistant to torsional deformation. This increases the rigidity of the spiral staircase and allows it to be made lighter.

6) The unit structure of the present invention can freely increase the stiffness of the beams by changing the shape of the step members and combining them with plate materials. The step members are manufactured by straightening, and the plate materials are manufactured by rolling strip steel. Therefore, spiral staircases of any stiffness can be manufactured inexpensively and freely.

According to the spiral staircase assembly method of the second aspect of the present invention, when applied to a "spiral staircase with a girder structure", the method first goes through a first step of erecting temporary supports on the base surface and fixing the step members to the spiral, a second step of fixing the board members to the spiral and a third step of detaching the multiple temporary supports from the step members, thereby achieving the following effect 7).

7) Conventionally, only the plate material with poor manufacturing precision was fixed first and then the step plate was assembled, which was inefficient and did not achieve the desired precision. However, in the first step, the step plate member is fixed in a spiral together with the temporary support material to the base surface, and then in the second step, the plate material is fixed to the step plate member, reversing the conventional procedure. As a result, plate material with poor manufacturing precision can be efficiently corrected into a spiral on the step plate member, whose spiral precision has already been determined.

FIG. 1 is a diagram showing the positional relationship between a step plate member and a plate material in the first embodiment. FIG. 2 is a diagram showing the structure of the step member of the first embodiment. FIG. 3 is an enlarged view showing the structure of the tread member in common for Examples 1, 2 and 3. FIG. 4 is a diagram showing a state in which the step plate member and the plate material are fixed to each other in the first embodiment. FIG. 5 is a diagram showing the step plate member and the fixing state of the plate material and the tread member in the first embodiment. FIG. 6 is a diagram showing the structure of the sub-floor fixing member according to the first embodiment. FIG. 7 is a diagram showing the structure of the upper floor fixing material of the first embodiment. FIG. 8 is a diagram showing the fixing state of the lower floor fixing material and the plate material in the first embodiment. FIG. 9 is a diagram showing the fixing state of the lower floor fixing material, the plate material and the tread member in the first embodiment. FIG. 10 is a diagram showing the fixing state of the upper floor fixing material and the plate material in the first embodiment. FIG. 11 is a diagram showing the fixing state of the upper floor fixing material, the plate material and the tread member in the first embodiment. FIG. 12 is a diagram showing the helical structure of the inner plate material of the first embodiment. FIG. 13 is a diagram showing the helical structure of the outer plate material of Example 1. FIG. 14 is a diagram showing the machining of the inner plate material into a spiral in the first embodiment. FIG. 15 is a diagram showing the machining of the outer plate material of Example 1 into a spiral. FIG. 16 is a diagram showing step 1 of the first embodiment. FIG. 17 is an enlarged view of part e in FIG. FIG. 18 is an enlarged view of the portion f in FIG. FIG. 19 is a diagram showing step 2 of the first embodiment. FIG. 20 is an enlarged view of part g in FIG. FIG. 21 is an enlarged view of part h in FIG. FIG. 22 is a diagram showing step 3 of the first embodiment. FIG. 23 is an enlarged view of part i in FIG. FIG. 24 is an enlarged view of part j in FIG. FIG. 25 is a diagram showing step 4 of the first embodiment. FIG. 26 is an enlarged view of part k in FIG. FIG. 27 is an enlarged view of portion l in FIG. FIG. 28 is a diagram showing step 5 of the first embodiment. FIG. 29 is a diagram showing the structure of the step member of the second embodiment. FIG. 30 is a diagram showing the step plate member and the fixing state of the plate material and the tread member in the second embodiment. FIG. 31 is a diagram showing the structure of the step member of the third embodiment. FIG. 32 is a diagram showing the step plate member and the fixing state of the plate material and the tread member in the third embodiment. FIG. 33 shows types of conventional straight staircases.

As a first embodiment of the present invention, a "spiral staircase with a beam staircase" will be described as an example of the "unit structure of a spiral staircase", which is the first aspect of the present invention.
Next, in the second aspect of the present invention, "a spiral staircase assembly method," each step of the first embodiment will be explained.
Furthermore, regarding variations of the present invention, examples 2 and 3 of different designs will be explained using a "spiral staircase with stringer stairs" as an example.

In Example 1, the first aspect of the present invention, the "unit structure of a spiral staircase," will be explained using an example of a "spiral staircase with a beam staircase" with reference to Figures 1 to 15.

(1) Positional relationship between the step plate member and the plate material (see Figure 1)
FIG. 1 is a diagram showing the positional relationship between a step member and a plate material in the first embodiment.
As can be seen in the AA', CC', and DD' cross sections, Example 1 is a "forced girder spiral staircase" in which a central vertical member 24 is sandwiched between a plate material (inner) 31 and a plate material (outer) 32.
The first figure shows a plan view of two tread steps, and below that is the A-A' cross section, as well as the B-B', C-C', D-D', and E-E' cross sections, as viewed vertically from the inside to the outside of the spiral. The direction of the spiral is the vertical section, and the radial direction perpendicular to that is the horizontal section.
Here, the step member 21 is composed of horizontal members 22 arranged horizontally and radially from the center of the spiral, and vertical members 24 joined vertically below the horizontal members 22 and arranged vertically and radially from the center of the spiral.
Furthermore, for the set of two rows of plate materials 36, the only thing geometrically that allows the insertion of a member to bundle them in a straight line is the "narrowness of the radial vertical surface 72 that includes the contact point 71 between the horizontal member 22 and the plate materials 31, 32."
The step member 21, consisting of a horizontal member 22 and a vertical member 24, bundles two rows of plate materials 31, 32, which are arranged in a spiral overall with their sides vertical, onto the side end face 25 of the vertical member 24, and presses them down and fixes them to the "contact point 71 between the horizontal member 22 and the plate materials 31, 32" on the lower edge of the horizontal member 22.

(2) Structure of the step member (see Figure 2)
2 is a diagram showing the structure of the step plate member 21 of Example 1. The FF' cross section at the beginning shows a plan view of the step plate member 21, and below that shows a GG' cross section as viewed transversely, and an HH' cross section and an II' cross section as viewed longitudinally from the inside to the outside of the spiral.
The step member 21, as viewed in plan and in cross section, comprises a horizontal member 22 and a vertical member 24 which is vertically connected to the lower part of the horizontal member 22.
The step plate member 21 of the first embodiment is fully and securely joined to a set of two rows of plate materials 31, 32 at the side end faces 25 of the respective vertical members by bolt fastening through plate material fastening holes 33.
In this way, the "single row force beam staircase" of Example 1 can be constructed by bundling two rows of plate materials 31, 32 with a step plate member 21 of one vertical member 24, which has an approximately T-shaped cross-section when viewed in cross section, while holding it down with the lower edge 23 of the horizontal member 22 and bundling it against the side end surface 25 of the vertical member (see also Figure 5).
The vertical member 24 is a channel steel whose side end faces 25 are flange surfaces connected to each other by a web, and the horizontal member 22 is an angle steel whose upper end is welded back-to-back to the back of the web of the vertical member 24 and whose one tip faces vertically downward and abuts against the plate materials 31, 32.
In this case, the intersection 74 between the "radial vertical plane 72 including the junction point between the horizontal member and the plate" and the "horizontal plane 73 including the junction point between the horizontal member and the plate" becomes the tip of the angle iron pointing vertically downward (see also Figure 1).
In this way, the step member 21 is manufactured by forming the constituent structural steel sections, the vertical member 24 being a channel steel and the horizontal member 22 being an angle steel, with the vertical member 24 and the horizontal member 22 being processed into a straight line.

(3) Structure of the tread member (see Figure 3)
3 is an enlarged view showing the structure of the tread member 11 in common to Examples 1 to 3. The first figure shows a plan view, and below that, on the left side, a transverse cross section seen from the J-J' cross section, and on the right side, a longitudinal cross section seen from the K-K' cross section.
The tread member 11 has a side end surface 14 which is generally an isosceles trapezoid in shape, with the inside of the spiral being narrower than the outside.
As seen in plan and cross section, the tread member 11 is composed of a grating 16 surrounded by a frame 15 made of angle iron.
Then, the tread fixing holes 12 on the tread member 11 side and the tread fixing holes 13 on the horizontal member 22 side that communicate with the tread fixing holes 12 are bolted to the horizontal member 22 of the step member 21 (also see FIG. 2).

(4) Fixing condition of the step plate member and the plate material (see Figure 4)
4 is a diagram showing the state of fixing the step plate member 21 and the plate materials 31, 32 in Example 1. The L-L' section at the beginning shows a plan view of the step plate member 21, and below that, the M-M' section as viewed horizontally, the N-N' section and the O-O' section as viewed vertically from the inside to the outside of the spiral are shown.
In the NN' and OO' cross sections, arrows show the state in which the step plate member 21 above, separate from the step plate member 21 at a level position relative to the MM' cross section, is inserted vertically downward from above into the narrow gap between the plate materials 31, 32.
The step member 21, consisting of a horizontal member 22 and a vertical member 24, has two rows of plate materials 31, 32 arranged in a spiral as a whole with the sides vertical, which are bound to the side end face 25 of the vertical member and pressed down on the lower side of the horizontal member 22, and both can be firmly fixed with bolts like joinery.

(5) Fixing state of step plate member and plate material to tread member (see Figure 5)
5 is a diagram showing the state of fixing the step plate member 21 and the plate materials 31, 32 and the tread member 11 in Example 1. The P-P' section at the beginning shows a plan view of the state of fixing the step plate member 21, the plate materials 31, 32 and the tread member 11, and below that, a Q-Q' section viewed in the transverse direction, an R-R' section and an S-S' section viewed in the longitudinal direction from the inside to the outside of the spiral are shown.
The RR' and SS' cross sections show, by arrows, a situation in which the tread member 11 is fixed from above to the horizontal member 22 of the step member 21 above, separate from the step member 21 at a level position relative to the QQ' cross section.

(6) Structure of the sub-floor fixing material (see Figure 6)
6 is a diagram showing the structure of the sub-floor fixing material 50 of Example 1. The first figure shows a plan view, and below that, a T-T' cross section viewed horizontally with an arrow, and a U-U' cross section and a V-V' cross section viewed vertically with an arrow from the inside to the outside of the spiral are shown.
The sub-floor fixing material 50 is a member for fixing two rows of plate material to the upper surface of the sub-floor concrete, and as seen in the plan and cross sections, consists of an arc member 51 and a vertical member 52 connected vertically to the upper part thereof.
The lower floor fixing member 50 is firmly joined to the two rows of plate members 31, 32 at the side end faces of the arc member 51 and the vertical member 52 by bolting through the plate member fixing holes 33, 35.
For the two rows of plate materials 31, 32 arranged in a spiral, the only geometric shape that allows the insertion of a member to bind them in a curved shape is an arc shape with a large and small curvature in a plan view of the two rows of plate materials. The arc member 51 matches this shape. For this reason, the sub-floor fixing member 50 fixes the two rows of plate materials to the sub-floor concrete with precision and efficiency, like joinery work.
The arc member 51 is a channel steel bent into a single curve with flange surfaces whose side end faces are connected to each other by a web, and the vertical member 52, which is also a channel steel of the same width and shape, is welded and fixed vertically upward.
The vertical member 52, like the step member 21, is a channel steel with flange surfaces whose side end faces are connected to each other by a web, and the horizontal member 53 is an angle steel that is welded back-to-back to the back of the web at the upper end of the vertical member 52 and has one tip facing vertically downward on the plate material.
In this case, the intersection 74 between the "radial vertical plane 72 including the junction point between the horizontal member and the plate" and the "horizontal plane 73 including the junction point between the horizontal member and the plate" becomes the tip of the angle iron pointing vertically downward (see also Figure 1).
In this way, the constituent structural steel of the lower floor fixing material 50 is made of channel steel for the vertical member 52, angle steel for the horizontal member 53, and channel steel of the same width and shape as the vertical member 52. The vertical member 52 and horizontal member 53 are manufactured by processing into a straight line, and the arc member 51 is manufactured by processing into a single curve.

(7) Structure of upper floor fixing material (see Figure 7)
7 is a diagram showing the structure of the upper floor fixing material 60 of Example 1. The first figure shows a plan view, and below that, an XX' cross section viewed horizontally, and a YY' cross section and a ZZ' cross section viewed vertically from the inside to the outside of the spiral are shown.
The upper floor fixing material 60 is a member that fixes two rows of plate material to the underside of the upper floor concrete, and as seen in the plan and cross sections, consists of an arc member 61 and a vertical member 62 that connects vertically to the bottom thereof.
The upper floor fixing member 60 is fully and strongly joined to the two rows of plate members 31, 32 at the side end faces of the arc member 61 and the vertical member 62 by bolting through the plate member fixing holes 33, 35.
For the two rows of plate materials 31, 32 arranged in a spiral, the only geometric shape that allows the insertion of a member to bind them in a curved shape is a circular arc shape with a large and small curvature in a plan view of the two rows of plate materials. The circular arc member 61 matches this shape. For this reason, the upper floor fixing member 60 fixes the two rows of plate materials to the lower floor concrete with precision and efficiency, like joinery work.
The arc member 61 is a channel steel bent into a single curve with flange surfaces whose side end faces are connected to each other by a web, and the vertical member 62, which is also a channel steel of the same width and shape, is welded and fixed vertically downward.
Unlike the step members 21, the vertical members 62 of the upper floor fixing member 60 do not have horizontal members.
In this way, the upper floor fixing material 60 is manufactured with the constituent steel sections such that the vertical members 62 are channel steel and have no horizontal members, while the arc members 61 are channel steel of the same width and shape as the vertical members 62, with the vertical members 62 being processed into a straight line and the arc members 61 being processed into a single curved line.

(8) Fixing status of the subfloor fixing material and the board material (see Figure 8)
8 is a diagram showing the state of fixing of the lower floor fixing member 50 and the plate members 31 and 32 in Example 1. The top plane shows a plan view of the lower floor fixing member 50, and below that shows an A1-A1' cross section taken along the arrows in the transverse direction, and a B1-B1' cross section and a C1-C1' cross section taken along the arrows in the longitudinal direction from the inside to the outside of the spiral.
The B1-B1' and C1-C1' cross sections show the horizontal member 53 and vertical member 52 at a level relative to the A1-A1' cross section, as well as the horizontal member 53 and vertical member 52 above them, which are integrated together via the arc member 51.
The lower floor fixing material 50, which is composed of a horizontal member 53, a vertical member 52 and an arc member 51, has two rows of boards 31, 32 arranged in a spiral overall with vertical sides, bundled together with the side end face 25 of the vertical member 52 and the side end face of the arc member 51, and pressed down against the lower edge of the horizontal member 53, so that it can be firmly bolted in like joinery work.

(9) Fixing conditions of the subfloor fixing material and the plate material to the tread member (see Figure 9)
9 is a diagram showing the fixing state of the lower floor fixing member 50 and the plate members 31 and 32 to the tread member 11 in Example 1. The top plane shows a plan view of the fixing state of the lower floor fixing member 50, the plate members 31 and 32, and the tread member 11, and below that shows a D1-D1' cross section taken along the arrows in the transverse direction, and an E1-E1' cross section and an F1-F1' cross section taken along the arrows in the longitudinal direction from the inside to the outside of the spiral.
In the E1-E1' and F1-F1' cross sections, arrows indicate a state in which the tread member 11 is fixed from above to the horizontal member 53 above the horizontal member 53 at a level position relative to the D1-D1' cross section.

(10) Fixing status of upper floor fixing material and board material (see Figure 10)
10 is a diagram showing the fixing state of the upper floor fixing material 60 and the plate materials 31, 32 in Example 1. The G1-G1' cross section at the beginning shows a plan view of the upper floor fixing material 60, and below that, the H1-H1' cross section, which is a cross-sectional view, and the I1-I1' cross section and the J1-J1' cross section, which are cross-sectional views of the spiral from the inside to the outside, are shown.
The I1-I1' and J1-J1' cross sections show that, apart from the vertical member 62 which is at a level position relative to the G1-G1' cross section, the horizontal member 22 and vertical member 24 which constitute the step plate member 21 on the lower side are integrated with the plate members 31 and 32.
The upper floor fixing material 60, consisting of a vertical member 62 and an arc member 61, has two rows of boards 31, 32 arranged in a spiral overall with vertical sides, which are bundled together at the side end faces of the vertical member 62 and the side end faces of the arc member 61 and can be firmly fixed with bolts like joinery.

(11) Fixing condition of upper floor fixing material and plate material to tread member (see Figure 11)
11 is a diagram showing the fixing state of the upper floor fixing member 60, the plate material, and the tread member 11 in Example 1. The K1-K1' cross section at the beginning shows a plan view of the fixing state of the upper floor fixing member 60, the plate materials 31 and 32, and the tread member 11 attached to the step plate member 21 on the lower step side, and below that, the L1-L1' cross section viewed in the transverse direction, and the M1-M1' and N1-N1' cross sections viewed in the longitudinal direction from the inside to the outside of the spiral are shown.
In the M1-M1' and N1-N1' cross sections, arrows indicate the state in which the tread member 11 is fixed from above to the lower step member 21 at a level position relative to the L1-L1' cross section and to the horizontal member 22 that constitutes it.

(12) Spiral structure of the inner plate and the outer plate (see Figures 12 and 13)
FIG. 12 is a diagram showing the spiral structure of the inner plate material 31 in the first embodiment, and FIG. 13 is a diagram showing the spiral structure of the outer plate material 32. As shown in FIG.
In both figures, a plan view of a set of two rows of plate materials 36 is shown at the top center, with the lines of the "radial vertical planes 72 including the contact points between the horizontal members and the plate materials" for all rows forming simple curves of different curvatures.
In both figures, a spiral side view of the plate materials (plate materials 31 and 32) is shown at the bottom center, along with a line of "horizontal plane 73 including the contact points between the horizontal member and the plate material" for all stages.
In both figures, in the plan view at the top center, the foot of the perpendicular line drawn from the intersection of the line of "radial vertical plane 72 including the junction between the horizontal member and the plate" and the simple curve of the plate (plate 31 and plate 32) to the line of "horizontal plane 73 including the junction between the horizontal member and the plate" in the side view becomes the spiral line at the upper end of the plate (plate 31 and plate 32), and the position taken downward from the spiral line at the upper end by the width of the plate (plate 31 and plate 32) becomes the spiral line at the lower end of the plate (plate 31 and plate 32).
In both figures, in the side view depicting a spiral, the plate material (plate material 31 and plate material 32) is divided into two parts, upper and lower, and splice materials (splice materials 41 and splice materials 42) wrap around both and are bolted together at plate material fixing holes 34.
In parts a and c, the upper floor fixing member 60 fixed to the upper floor concrete 81 and the fixing state of the plate materials (plate materials 31 and 32) to the top step plate member 21 are shown aligned with the line of "horizontal plane 73 including the contact point between the horizontal member and the plate materials." Also, in parts b and d, the fixing state of the plate materials (plate materials 31 and 32) to the lower floor fixing member 50 fixed to the lower floor concrete 82 are shown aligned with the line of "horizontal plane 73 including the contact point between the horizontal member and the plate materials."
As shown in parts a and c, and parts b and d, the uppermost edge of the spiral of the plate materials (plate materials 31 and plate materials 32) matches and ends with the lower surface 76 of the upper floor concrete, and the lowermost edge of the spiral of the plate materials (plate materials 31 and plate materials 32) matches and ends with the upper surface 77 of the lower floor concrete. In this way, the two rows of plate materials 36 are firmly fixed to the upper floor concrete 81 and the lower floor concrete 82 by the upper floor fixing members 60 and the lower floor fixing members 50 (see also Figures 8 and 10).

(13) Machining the inner plate into a spiral and the outer plate into a spiral (see Figures 14 and 15)
FIG. 14 is a diagram showing the machining of the inner plate material of Example 1 into a spiral, and FIG. 15 is a diagram showing the machining of the outer plate material of Example 1 into a spiral.
In both figures, the plate material on the left is a two-dimensional rectangular steel plate, which is rolled into a three-dimensional spiral shape on the right. The plate material steel plate is cut into a predetermined shape after plate material fixing holes 34 are drilled at predetermined positions in the two-dimensional rectangular steel plate before rolling.

Next, in the second aspect of the present invention, the "spiral staircase assembly method", each step of the first embodiment will be explained with reference to Figs. 16 to 28.
16, 19, 22, 25, and 28, the upper figures show a "plan view" together with a "center line" of a simple curve drawn with respect to the center of the spiral, and the lower figures show a "developed view" developed to the side at the "center line." Here, plate material 30 is a collective term for each plate material of different shapes, and shows both plate material (inner) 31 and plate material (outer) 32.
In addition, each of Figures 17, 20, 23, and 26 is an enlarged view of a portion of the "planar situation", and each of Figures 18, 21, 24, and 27 is an enlarged view of a portion of the "side situation".
Here, each step is as follows:
Step 1: Fixing the upper floor fixing member 60 and the lower floor fixing member 50. Step 2: Intermittent placement of the temporary support member 90 and the step plate member 21. Step 3: Attaching the plate members 31 and 32. Step 4: Attaching the step plate member 21 and the tread member 11, and removing the temporary support member 90. Step 5: Completion.

The first embodiment is a "forced beam spiral staircase." The "forced beam spiral staircase" is made up of step plate member 21, plate members 31 and 32, splice members 41 and 42, tread member 11, lower floor fixing member 50, and upper floor fixing member 60, and uses temporary support members 90, distance adjustment members 93, jack bases 91, and clamps 92 as temporary materials.

(14) Step 1: Fixing the lower floor fixing member 50 and the upper floor fixing member 60 (see Figures 16 to 18)
The lower floor fixing material and the upper floor fixing material, which form the starting and ending points of the spiral, are anchored at predetermined positions on the upper surface 77 of the lower floor concrete and the lower surface 76 of the upper floor concrete, respectively.
The lower floor fixing material 50, which is made up of a horizontal member 53, a vertical member 52 and an arc member 51, has two rows of boards 31, 32 arranged in a spiral overall with vertical sides, which are bundled together with the side end face 25 of the vertical member 52 and the side end face of the arc member 51 and pressed down on the lower edge 23 of the horizontal member 53, and can be bolted in place firmly like joinery (see also Figure 8).
The upper floor fixing material 60, consisting of a vertical member 62 and an arc member 61, has two rows of boards 31, 32 arranged in a spiral overall with vertical sides, which are bound to the side end faces of the vertical member 62 and the arc member 61, and can be bolted together firmly like joinery (an enlarged view is not shown, but see also Figure 10).

(15) Step 2: Intermittent placement of temporary support members and step members (see Figures 19 to 21)
The step members 21 are intermittently fixed to a pair of temporary support members 90 in the same radial direction with clamps 92, while adjacent step members 21 are successively connected in series with distance adjustment members 93 from the lower floor fixing member 50 to the upper floor fixing member 60, and the whole is fixed in a predetermined spiral.
The step member 21 is composed of horizontal members 22 arranged horizontally and radially from the center of the spiral, and vertical members 24 joined vertically downward to the horizontal members 22 and arranged vertically and radially from the center of the spiral (see also Figure 1).
The step plate members 21 are fixed radially by clamps 92 at the top of a set of two temporary support members 90 which are erected on a jack base 91 which is positioned and fixed in advance in large and small arcs on the upper surface 77 of the sub-floor concrete, and adjacent step plate members are spirally connected by spacing adjustment members 93.
The height of the step member 21 is adjusted by the jack base 91, and the step member 21 is adjusted to a spiral shape by the spacing adjustment member 93, thereby stabilizing the entire structure.
The temporary support material 90 is erected on a jack base 91 and fixed to the step member 21 with a clamp 92, so it is easy to attach and remove, and the distance adjustment material 93 is bolted to a distance adjustment material fixing bracket 97, a small angle-shaped piece that is bolted to the center of the upper surface of the horizontal member 22 of the step member 21, so it is easy to attach and remove.
The distance adjustment material 93 is composed of, from the center to both ends, a turnbuckle 94, a steel bar 95 with a perforated plate, and a perforated plate 96. The distance of the distance adjustment material 93 is adjusted by the turnbuckle 94, and the perforated plate fixing bracket communicating hole 98 of the perforated plate 96 is fixed to the distance adjustment material fixing bracket 97 by the perforated plate fixing bracket communicating bolt nut 99.
The small angle-shaped piece of distance adjusting material fixing bracket 97 is fixed in advance to the center of the horizontal member 22 through the fixing bracket horizontal member communication hole 100 with a fixing bracket horizontal member communication bolt nut 101.

(16) Step 3: Attaching the boards (see Figures 22 to 24)
The two-part plate member (plate member 31 and plate member 32) consisting of an upper half and a lower half, which form two rows of spirals overall, are attached to the step plate member 21 in order from the lower half to the upper half.
The lower half of the plate material has splices (splices 41 and 42) welded to it in advance so that the upper half can be wrapped around it and attached. The two are then wrapped around each other and bolted together at the plate material fixing holes 34.
For the set of two rows of plate materials 36, the only thing that geometrically allows the insertion of a member to bundle them in a straight line is the "narrowness of the radial vertical surface 72 that includes the contact points between the horizontal member 22 and the plate materials 31, 32" (see also Figure 1).
The step member 21, consisting of a horizontal member 22 and a vertical member 24, has two rows of plate materials 31, 32 arranged in a spiral overall with their sides vertical, which are bundled together at the side end face 25 of the vertical member and pressed down and fixed at the "contact point 71 between the horizontal member and the plate materials" on the lower edge of the horizontal member 22 (see also Figure 4).
The step plate member 21 is fully and securely joined to the two rows of plate members 31, 32 at the side end faces 25 of the respective vertical members 24 by bolt fastening through plate member fastening holes (vertical member side) 33 (see also FIG. 2).
The lower floor fixing member 50 is fully and strongly joined to the two rows of plate members 31, 32 at the side end faces of the arc member 51 and the vertical member 52 by bolting through the plate member fixing holes 33, 35 (see also Figure 6).
The upper floor fixing member 60 is fully and strongly joined to the two rows of plate members 31, 32 at the side end faces of the arc member 61 and the vertical member 62 by bolting through the plate member fixing holes 33, 35 (an enlarged view is not shown, see also Figure 7).

(17) Step 4: Installation of step plate members and tread members, removal of temporary support members (see Figures 25, 26 and 27)
After removing and dismantling the spacing adjuster 93 and the angle-shaped spacing adjuster fixing brackets 97 for fixing the spacing adjuster 93 from the intermittent step plate members 21 and the two rows of plate members 31, 32 which are set in a spiral, the remaining step plate members 21 are fixed with bolts.
The tread member 11 has a separate structure that is later bolted to the horizontal member 22, making it easy to assemble by bolting the step plate member 21 to the plate materials 31, 32 (see Figures 5 and 9 together).
Then, the tread fixing holes 12 on the tread member 11 side and the tread fixing holes 13 on the horizontal member 22 side are fixed to the horizontal member 22 of the step plate member 21 with bolts (see both Figures 2 and 3).
Once the remaining installation of the step plate member 21 and tread member 11 is completed, the temporary support member 90 and jack base 91 are removed and dismantled.

(18) Step 5: Completion (see Figure 28)
Through the above steps, the "single row of force beam stairs" of Example 1 is completed.
A "single-row force beam staircase" can be constructed by bundling one set of two rows of board materials, i.e., two rows of board materials, with a step board member having an approximately T-shaped cross-section of a single vertical member, while holding them down at the bottom edge of the horizontal member, and bundling them against the side end face of the vertical member.
The “forced beam spiral staircase” comprises a step plate member 21 , plate members 31 , 32 , splice members 41 , 42 , a tread member 11 , a lower floor fixing member 50 , and an upper floor fixing member 60 .
The lower floor fixing member 50 and the upper floor fixing member 60, which form the starting and ending points of the spiral, are anchored to predetermined positions on the upper surface 77 of the lower floor concrete and the lower surface 76 of the upper floor concrete, respectively, and all remaining components are assembled using bolts.

In the second embodiment, which is the first aspect of the present invention, the "unit structure of a spiral staircase", the differences between the first embodiment (1) to (13) and the first and second aspects (2) and (5) will be explained with reference to Figs. 29 and 30 using a "spiral staircase with side beams".
The second aspect of the present invention, the "method of assembling a spiral staircase", is omitted here because it is generally the same as in Example 1. Here, the plate material 30 is a general term for each plate material having a different shape.

(2) Structure of the step member (see FIG. 29)
29 is a diagram showing the structure of the step plate member 21 of Example 2. The top plane shows a plan view of the step plate member 21, and below that shows a T1-T1' cross section viewed in the transverse direction, and a U1-U1' cross section, a V1-V1' cross section, a W1-W1' cross section, and an X1-X1' cross section viewed in the longitudinal direction from the inside to the outside of the spiral.
The step member 21, as viewed in plan and in cross section, comprises a horizontal member 22 and two vertical members 24 connected vertically below the horizontal member 22.
The step plate member 21 of Example 2 is fully joined to two sets of plate members 30 (four rows in total) by bolting through plate member fixing holes 33 at the side end faces 25 of each vertical member.
In this way, the "side girder staircase" of Example 2 can be constructed by bundling the central two rows of board materials of the four rows of board materials 30 (two sets of two rows each) with the step board member 21 of two vertical members 24, which has an approximately π-shaped cross section in cross section, while holding them down with the lower edge 23 of the horizontal member 22 and bundling them with the side end face 25 of the vertical member (see also Figure 30).
As in Example 1, the vertical member 24 is a channel steel whose side end faces 25 are flange surfaces connected to each other by a web, and the horizontal member 22 is an angle steel whose upper end is welded back-to-back to the back of the web of the vertical member 24 and whose one tip faces vertically downward and contacts the plate material 30.
In this case, the intersection 74 between the "radial vertical plane 72 including the junction point between the horizontal member and the plate" and the "horizontal plane 73 including the junction point between the horizontal member and the plate" becomes the tip of the angle iron pointing vertically downward (see also Figure 30).
In this way, the step member 21 is manufactured by forming the constituent structural steel sections, the vertical member 24 being a channel steel and the horizontal member 22 being an angle steel, with the vertical member 24 and the horizontal member 22 being processed into a straight line.

(5) Fixing status of step plate member and plate material to tread member (see Figure 30)
30 is a diagram showing the state of fixing the step plate member 21 and the plate material 30 to the tread member 11 in Example 2. The top plane shows a plan view of the state of fixing the step plate member 21, the plate material 30 and the tread member 11, and below that shows a Y1-Y1' cross section viewed in the transverse direction, and a Z1-Z1' cross section, an A2-A2' cross section, a B2-B2' cross section and a C2-C2' cross section viewed in the longitudinal direction from the inside to the outside of the spiral.
The Z1-Z1', A2-A2', B2-B2', and C2-C2' cross sections show with arrows the situation in which the tread member is fixed from above to the horizontal member 22 of the step member 21 on the upper side, separate from the step member 21 at a level position relative to the Y1-Y1' cross section.
In the second embodiment, the two outer rows of plate materials 30, but not the two central rows of plate materials 30, are covered by the tread members 11 and are therefore not held down by the lower edges 23 of the horizontal members 22. However, the two central rows of plate materials 30 are narrow and have this function, so they have the same effect as the first embodiment.

In the third embodiment, the first aspect of the present invention, the "unit structure of a spiral staircase", will be explained with reference to Figures 31 and 32, taking a "spiral staircase with side beams" as an example, with particular differences (2) and (5) from (1) to (13) already explained in the first embodiment. The "spiral staircase with side beams" in the third embodiment has a different design from the "spiral staircase with side beams" in the second embodiment, in terms of the structure of the step members and the composition of the boards.
The second aspect of the present invention, the "method of assembling a spiral staircase", is omitted here because it is generally the same as in Example 1. Here, the plate material 30 is a general term for each plate material having a different shape.

(2) Structure of the step plate member (see FIG. 31)
31 is a diagram showing the structure of the step plate member 21 of Example 3. The top plane shows a plan view of the step plate member 21, and below that shows a D2-D2' cross section as viewed transversely, and an E2-E2' cross section, an F2-F2' cross section, a G2-G2' cross section, and an H2-H2' cross section as viewed longitudinally from the inside to the outside of the spiral.
The step member 21, as viewed in plan and in cross section, comprises a horizontal member 22 and a vertical member 24 which is vertically connected to the lower part of the horizontal member 22.
In Example 3, the plate material is made of two plates stacked on top of each other in each set of two rows, with the outer plate material being wide and covering the tread member, and the inner plate material in contact with the outer plate material being narrower and held down by the edge of the lower side 23 of the horizontal member 22 and fixed to the side end face of the vertical member.
In the step plate member 21 of Example 3-2, each row of two plates is joined to a two-ply plate member 30 by bolting through plate member fixing holes 33 at the side end faces 25 at the outermost edges in the transverse direction of each vertical member.
In this way, the "side girder staircase" of Example 3 can be constructed by stacking two boards in each row of a set of two rows, with the outer board being wide and covering the tread member, and the inner board contacting the outer board being narrow, and bundling the two vertical members 24 with the step board members 21, which have an approximately π-shaped cross-section when viewed in cross section, while holding them down with the edge of the lower side 23 of the horizontal member 22, and binding them to the side end face 25 of the vertical member (see also Figure 32).
As in Example 1, the vertical member 24 is a channel steel whose side end faces 25 are flange surfaces connected to each other by a web, and the horizontal member 22 is an angle steel whose upper end is welded back-to-back to the back of the web of the vertical member 24 and whose one tip faces vertically downward and contacts the plate material 30.
In this case, the intersection 74 between the "radial vertical plane 72 including the junction point between the horizontal member and the plate" and the "horizontal plane 73 including the junction point between the horizontal member and the plate" becomes the tip of the angle iron pointing vertically downward (see also Figure 32).
In this way, the step member 21 is manufactured by forming the constituent structural steel sections, the vertical member 24 being a channel steel and the horizontal member 22 being an angle steel, with the vertical member 24 and the horizontal member 22 being processed into a straight line.

(5) Fixing state of step plate member and plate material to tread surface member (see Figure 32)
32 is a diagram showing the state of fixing the step plate member 21 and the plate material 30 to the tread member 11 in Example 3. The top plane shows a plan view of the state of fixing the step plate member 21, the plate material 30 and the tread member 11, and below that shows an I2-I2' cross section viewed in the transverse direction, and a J2-J2' cross section, a K2-K2' cross section, an L2-L2' cross section and an M2-M2' cross section viewed in the longitudinal direction from the inside to the outside of the spiral.
The J2-J2', K2-K2', L2-L2', and M2-M2' cross sections show with arrows the situation in which the tread member 11 is fixed from above to the horizontal member 22 of the upper step member 21, separate from the step member 21 at a level position relative to the I2-I2' cross section.
In the third embodiment, the two overlapping outer plate members 30 are wide and cover the tread members, so they are not held down by the lower edge 23 of the horizontal member 22. However, the inner plate member 30 that contacts the outer plate member 30 is narrow and has this function, so that the same effect as in the first embodiment is obtained.

Above, Examples 1, 2, and 3 have been described as embodiments for implementing the present invention. As a result, the first aspect of the present invention can achieve the following additional effects 8) to 11), and the second aspect of the present invention can achieve the following additional effects 12) to 14).

8) The step plate members can be equipped with an appropriate number of vertical members according to the number of plate rows. Therefore, for each structural type of "spiral staircase with braced staircase", "spiral staircase with side beam staircase", and "spiral staircase with box section", a rational unit structure can be provided by the following measures.
A "single-row force beam staircase" can be constructed by bundling one set of two rows of board materials, i.e., two rows of board materials, with a step board member having an approximately T-shaped cross-section of a single vertical member, while holding them down at the bottom edge of a horizontal member, and binding them to the side end face of the vertical member (see Example 1).

A "two-row force beam staircase" can be constructed by bundling two sets of two-row boards (i.e., four rows) of boards with two vertical members, each of which has a roughly π-shaped cross section, against the side end faces of the respective vertical members while holding them down at the bottom edges of the horizontal members (not shown).

A "side girder staircase" can be constructed by bundling two sets of two-row boards (i.e., four rows) of boards with the bottom edge of the horizontal member of the step board member with an approximately π-shaped cross section of the two vertical members, while holding them down. In this case, the boards can be fixed precisely even if only the outermost two rows of boards are made wide enough to cover the side end faces of the treads (see Example 2).

A "stringer staircase," which is one form of "side girder staircase," can be constructed by making the outermost boards wider so that they cover the side end faces of the treads, and cutting them into a jagged stringer shape to match the treads and risers (not shown).

A "box section spiral staircase" can be made by adding a base plate to the above-mentioned "stringer staircase." The base plate can be a steel plate that contributes to rigidity, or a resin plate that excels in design expression. Using this method, a wooden and Gothic style "box section spiral staircase" like the "St. Joseph's Spiral Staircase" can be freely created with decoration (not shown). In addition, "box section spiral staircases" made of "solid reinforced concrete," which have long construction times and are vulnerable to deformation, can be replaced by the present invention, which has excellent construction time reduction and deformation followability.

9) If the vertical members are made of shaped steel, which has flange surfaces whose side end faces are connected to each other by webs and is highly versatile and easy to process, the step members can be manufactured inexpensively and with high precision. The shaped steel can be a channel steel, H-shaped steel, I-shaped steel, etc.

10) Conventionally, "steel" "spiral staircases with side girder stairs" have a single side girder, which is costly to transport and erect, and conversely, if it is divided, the joints become weak points in the girder structure due to stress concentration, causing shaking and reducing durability. However, even if the plate material is divided, it is fixed with bolts to the side end faces of multiple vertical members via splice plates. This allows stress to be transmitted smoothly and does not become a structural weak point.

11) Traditionally, "steel" "spiral staircases with side beams" are limited to either a spiral or straight line shape, and do not support a combination of both. However, even if the plate material is divided into a spiral and straight line shape, it is fixed with bolts to the side end faces of multiple vertical members via splice plates. This allows stress to be transmitted smoothly, and the structure can be assembled as a continuous beam structure with a combination of spiral and straight lines.

12) Multiple pairs of temporary support members are erected on the base surface on arcs of differing curvature, each pair sharing a vertical plane radially from the spiral center, with a jack base at the bottom end, and the horizontal members of the step members sharing the vertical plane are clamped at two points. The horizontal members are then fixed to adjacent horizontal members, which are fixed in the same way, with spacing adjustment members, and the heights are adjusted with the jack bases and the planar positions are adjusted with the spacing adjustment members so that the horizontal members are horizontal and the vertical members are vertical, and so that they match the vertical planes in the radial directions, and so that they line up in a spiral in a stereoscopic view. In this way, the step members draw the specified spiral with precision and efficiency.

13) Conventionally, it was difficult to create a combination of spiral and straight lines unless it was a "box-section spiral staircase" made of "solid reinforced concrete," which would take a significant amount of construction time. However, by continuously arranging the temporary support materials in an arc shape for the spiral section and in a straight line for the straight section, it is possible to easily create a combination of spiral and straight lines.

14) Conventional "spiral staircases with side beams" and "spiral staircases with tension beams" "cannot be assembled and inspected in advance at the factory, and quality is not stable. However, if the step plate members are clamped to the temporary supports in the first step, and the step plate members and plate members are bolted together in the second step, assembly is reproducible. Therefore, assembly inspection can be carried out in advance at the factory, and quality and precision are stable. In addition, there is no need to transport the spiral plate members as a single unit, which reduces transportation costs.

1 Force beam staircase, 2 Side beam staircase, 3 Stringer staircase, 4 Force beam, 5 Side beam, 6 Stringer, 10 Tread, 11 Tread member, 12 Tread fixing hole (tread member side), 13 Tread fixing hole (horizontal member side), 14 Side end face of tread, 15 Frame, 16 Grating, 20 Step plate, 21 Step plate member, 22 Horizontal member, 23 Bottom edge of horizontal member, 24 Vertical member, 25 Side end face of vertical member, 26 Bottom edge of vertical member, 30 Plate material, 31 Plate material (inner side), 32 Plate material (outer side), 33 Plate material fixing hole (vertical member side), 34 Plate material fixing hole (plate material side), 35 Plate material fixing hole (arc member side), 36 Set of two rows of plate material, 39 Plate material fixing bolts and nuts, 40 Splice material, 41 Splice material (inner side), 42 Splice material (outside), 50 Lower floor fixing material, 51 Circular arc member (Lower floor fixing material), 52 Vertical member (Lower floor fixing material), 53 Horizontal member (Lower floor fixing material), 60 Upper floor fixing material, 61 Circular arc member (Upper floor fixing material), 62 Vertical member (Upper floor fixing material), 70 Intersection line between "radial vertical plane" including junction point between horizontal member and plate material and "horizontal plane", 71 Junction point between horizontal member and plate material, 72 Radial vertical plane including junction point between horizontal member and plate material, 73 Horizontal plane including junction point between horizontal member and plate material, 74 Intersection line between "radial vertical plane including junction point between horizontal member and plate material" and "horizontal plane including junction point between horizontal member and plate material", 75 Spiral center, 76 Underside of upper floor concrete, 77 Upper surface of lower floor concrete, base surface, 81 Upper floor concrete, 82 Lower floor concrete, 83 Floor covering material, 90 Temporary support material, 91 Jack base, 92 clamp, 93 distance adjustment material, 94 turnbuckle, 95 perforated plate attached steel bar, 96 perforated plate, 97 distance adjustment material fixing bracket, 98 perforated plate fixing bracket connecting hole, 99 perforated plate fixing bracket connecting bolt nut, 100 fixing bracket horizontal member connecting hole, 101 fixing bracket horizontal member connecting bolt nut

Claims (2)

A unit structure of a spiral staircase,
A plurality of step members each including a horizontal member having a tread surface on an upper side and one or more vertical members vertically connected to a lower side of the horizontal member;
A plurality of rows of planks;
It is composed of
The plurality of step members are arranged in a spiral as a whole, with the horizontal members of each step member being horizontal and the vertical members of each step member being vertical,
The plurality of rows of plate members are arranged in a spiral shape as a whole with their side surfaces generally vertical,
A unit structure of a spiral staircase, characterized in that at least two of the multiple rows of boards are fixed facing either side end face of the vertical member and the lower edge of the horizontal member. A method for assembling a modular spiral staircase, comprising the steps of:
A plurality of step plate members and a plurality of rows of plate members each including a horizontal member having a tread surface on an upper side and one or more vertical members vertically connected to a lower side of the horizontal member are prepared;
A first step is to fix the vertical members of the plurality of step members vertically and the horizontal members horizontally to a plurality of temporary support members that are erected in an arc shape on a base surface in advance, thereby forming a spiral as a whole;
a second step of fixing at least two or more rows of the plurality of rows of plate materials to face either side end surface of the vertical member and the lower side of the horizontal member to form a spiral as a whole;
and a third step of detaching the plurality of temporary support members from the plurality of step members.

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