Steel staircase and stairwell structure with fire-resistant covering means

Abstract

Since the steel frame stairs with the fire resistive covering means can be manufactured in a factory and carried in a job site without damage, fire resistive covering work in the job site can be reduced.SOLUTION: An upper landing 8 and a lower landing 11 are arranged in a stair part 6 including a tread 4, and are sandwiched by a steel stringer 16 to form a steel frame stair 1. Fire-resistant rock wool 27 is filled in a fire-resistant covering frame 24 formed along the lower surface of the steel frame stairs 1, and the fire-resistant covering frame 24 is fixed to the lower surface of the steel frame stairs 1. Further, a fireproof ceiling board 23 is formed along the lower surface of the fireproof covering frame 24, and the upper surface of the fireproof ceiling board 23 is fixed to the lower surface of the fireproof covering frame 24. Then, a flame-retardant gasket 30 is arranged on the outer periphery of the steel staircase 1 (especially on the 17a of the outer surface of the open string 16) above the fire-resistant coating frame 24 to form a steel staircase 32 with a fire-resistant coating means. When the steel staircase 32 with the fireproof coating means is installed in the staircase room 40, the flame-retardant gasket 30 is brought into close contact with the inner surface 43a of the staircase room wall 43 to prevent the formation of a clearance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a steel staircase with fire-resistant covering means and a staircase structure using this steel staircase. [Background technology]

[0002] In buildings, especially high-rise buildings, stairs installed within stairwells surrounded by fire-resistant walls are used as evacuation stairwells in the event of a fire. The Building Standards Act stipulates that the walls, columns, beams, and floors of stairwells must be fire-resistant for one hour, but no specific regulations apply to the stairwell itself (Article 112, Enforcement Order of the Building Standards Act, Fire Compartments). While reinforced concrete stairs are generally constructed on-site by assembling formwork and rebar and pouring concrete, steel-frame stairs, consisting of treads sandwiched between steel stringers, are more commonly manufactured in factories and attached to the building frame (beams, etc.) at the construction site. This is because steel-frame stairs require less on-site work, are highly precise, and are lightweight, making them more effective. However, compared to reinforced concrete stairs, the fire resistance of steel-frame stairs is not as sufficient. For this reason, when steel staircases are used in fire compartments, the underside of the staircase is typically treated as a wall or floor, with ALC (lightweight aerated concrete) panels or fireproof boards (gypsum boards) attached to make the compartments compatible. However, this method requires the steel staircase to be attached to the main structure, and then these components must be attached to the underside of the staircase on-site, which increases on-site work. Furthermore, since the work requires workers to work facing upwards, it is very difficult to work with, and there are safety issues, such as the components falling during installation. Furthermore, when steel staircases installed inside staircase rooms are used as work stairs, the stairs must be closed while the components are being installed, blocking work routes to the upper and lower floors, negatively impacting safety and work efficiency. In addition, there have been attempts to fix ALC panels or fireproof boards to steel staircases in advance at a factory and then transport them from the factory to the construction site in that state, but this was not practical because the steel staircase would twist and break during the fabrication of the steel staircase at the factory, during transport to the site, and during installation and lifting at the site. This has been a particularly significant problem when installing two sets of stairs with opposite directions, known as X-stairs, side by side in a staircase room to double the amount of people moving around (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-93742 [Patent Document 2] Japanese Patent Application Publication No. 4-309650 [Patent Document 3] Japanese Patent Application Publication No. 2023-97570 Summary of the Invention [Problem to be solved by the invention]

[0004] There have been proposals to make the landings and staircases (treads) fireproof by pouring concrete on-site (Patent Document 2), but this has not been possible to achieve a fireproof structure for the entire steel staircase. In particular, it was difficult to fireproof the underside of the steel stringers. Furthermore, in wooden buildings, there have been many proposals to fireproof the underside of wooden stairs installed inside staircases by forming fireproof covering means on-site (for example, Patent Document 3), but there have been no proposals to fireproof stairs in advance at a factory. [Means for solving the problem]

[0005] The present invention solves the above-mentioned problems by arranging the fire-resistant covering means, which is equipped with a fire-resistant ceiling plate that covers the underside of the steel staircase, and by having the outer surface of the fire-resistant covering means protrude outward in a plan view from the outer surface of the stringers to form a steel staircase with fire-resistant covering means, or by using this steel staircase with fire-resistant covering means and applying an elastic flame-retardant gasket to form a staircase structure.

[0006] That is, among the inventions relating to the steel staircase with fire-resistant covering means, the invention described in claim 1 is a steel staircase constructed by sandwiching "step-like treads" or "step-like treads and landing portion" between the inside surfaces of steel stringers, and by forming fire-resistant covering means on the steel staircase, characterized by being configured as follows. (1) The fire-resistant covering means is configured by disposing a fire-resistant covering material between the upper surface of a fire-resistant ceiling board that can cover the underside of the steel staircase and the underside of the steel staircase. (2) The outer surface of the fire-resistant covering means on the side of the stringer protrudes outward in a plan view from the outer surface of the stringer.

[0007] The invention described in claim 2 is a steel staircase with fire-resistant covering means in the invention described in claim 1, configured as follows. (1) The fire-resistant covering means is configured by fixing a fire-resistant ceiling board having a shape that follows the outer surface of the fire-resistant covering material frame in a plan view to the underside of a fire-resistant covering material frame that covers the underside of the steel staircase and follows the underside of both stringers in a plan view, and filling the fire-resistant covering material frame with fire-resistant rock wool. (2) The fire-resistant coating material frame of the fire-resistant coating means was fixed to the underside of the stringer. The invention described in claim 3 is a steel staircase with fire-resistant covering means in the invention described in claim 2, configured as follows. (1) The underside of the stringer of the steel staircase and the top surface of the steel fire-resistant coating material frame, and the top surface of the steel fire-resistant coating material frame and the top surface of the steel fire-resistant ceiling panel were welded together.

[0008] The invention described in claim 4 is a steel staircase with fire-resistant covering means in the invention described in claim 1, configured as follows. (1) An elastic fire-retardant gasket is fixed to the upper surface of the fire-resistant covering means and to the outer surfaces of both stringers. (2) The outer peripheral surface of the flame-retardant gasket protrudes outward in plan view from the outer surface of the fire-resistant covering means. The invention described in claim 5 is a steel staircase with fire-resistant covering means in the invention described in claim 4, configured as follows. (1) The entire circumference of the fire-resistant covering means protrudes outward from the outer surface of the steel staircase in the horizontal direction when viewed in plan, all around the steel staircase. (2) An elastic flame-retardant gasket is fixed to the upper surface of the fire-resistant covering means around the entire periphery of the steel staircase in a plan view. (3) The outer peripheral surface of the flame-retardant gasket protrudes outward beyond the outer surface of the fire-resistant covering means.

[0009] Furthermore, among the inventions relating to staircase structures, the invention described in claim 6 is a staircase structure in which a steel staircase with fire-resistant covering means is erected between the staircase floor located above on one side of the staircase walking direction and the staircase floor located below on the other side, in a staircase spanning upper and lower floors that is partitioned by staircase walls of a specified fire-resistant construction and has a staircase floor of a specified fire-resistant construction, and the staircase structure is configured as follows. (1) The fire-resistant covering means is configured by disposing a fire-resistant covering material between the upper surface of a fire-resistant ceiling board that can cover the underside of the steel staircase and the underside of the steel staircase. (2) The outer surface of the fire-resistant covering means protrudes outward in a plan view from the outer surface of the stringer, and the outer surface of the fire-resistant covering means abuts against the wall surface of the staircase wall or is positioned in a position near the wall surface of the staircase wall. (3) An elastic flame-retardant gasket is attached to the upper surface of the fire-resistant covering means between the outer surfaces of the stringers and the wall surface of the staircase wall, and the flame-retardant gasket is arranged on the outer surfaces of the stringers over the entire length in the direction of stair walking.

[0010] Furthermore, the invention described in claim 7 is a staircase structure according to the invention described in claim 6, characterized in that it is configured as follows. (1) A central staircase wall is placed approximately in the center of the staircase wall in the direction of stairway walking, and the staircase is divided vertically into two sections, a first section and a second section, with the central staircase wall as the dividing line. A steel staircase with a first fire-resistant covering means is erected in the first section, and a steel staircase with a second fire-resistant covering means is erected in the second section, and the first steel staircase with a fire-resistant covering means and the second steel staircase with a fire-resistant covering means are arranged crosswise on the same floor. (2) In the steel staircase with the first fire-resistant covering means and the steel staircase with the second fire-resistant covering means, the outer surfaces of the fire-resistant covering means protrude outward in a plan view from the outer surfaces of the stringers, and the outer surfaces of the fire-resistant covering means abut against the wall surfaces of the staircase walls and the central staircase wall, or are positioned in the vicinity of the wall surfaces of the staircase walls. (3) In the steel staircase with the first fire-resistant covering means and the steel staircase with the second fire-resistant covering means, in the first section and the second section, elastic flame-retardant gaskets are tightly attached to the upper surface of each fire-resistant covering means, between the outer surface of the stringer and the wall surface of the central staircase wall, and between the outer surface of the stringer and the wall surface of the staircase wall, and the flame-retardant gaskets are arranged on the outer surface of each stringer over the entire length of the staircase in the direction of walking.

[0011] When the steel staircase with fire-resistant coating is applied to a staircase, as mentioned above, a small gap often remains between the staircase wall and the outer surface of the stringers of the steel staircase. From the viewpoint of fire resistance, there is a risk that flames and smoke may move up and down through this gap in the event of a fire, sandwiching the steel staircase. In addition to addressing the above issue, measures to prevent this must also be taken. From this perspective, the invention relating to the steel staircase with fire-resistant coating addresses the issue with the following measures. In the steel staircase with fire-resistant covering means described in claim 1, the outer surface of the fire-resistant covering means (any of the components constituting the fire-resistant covering means, i.e., the fire-resistant ceiling board and / or the fire-resistant covering material) is configured to protrude outward in a plan view (horizontally) from the outer surface of the stringers. This allows the outer surface of the fire-resistant covering means to abut against the wall surface of the staircase chamber, thereby sealing the "gap." In addition, in the invention of the steel staircase with fire-resistant covering means described in claim 2, the outer surfaces of the fire-resistant covering material frame and / or fire-resistant ceiling board and / or fire-resistant covering material, which are the components that make up the fire-resistant covering means, can be abutted against the wall surface of the staircase wall, thereby similarly sealing the ``gap.'' In the invention of the steel staircase with fire-resistant covering means described in claim 4, the outer surface of the flame-retardant gasket protrudes outward in a plan view (horizontal direction) from the outer surface of the fire-resistant covering means, so that the outer surface of the flame-retardant gasket can abut against the wall surface of the staircase wall, at least on the stringer side of the steel staircase with fire-resistant covering means, and the "gap" can be more effectively closed. Even if the steel staircase with fire-resistant covering means does not have a flame-retardant gasket on any surface other than the stringer side, the outer surface of any member of the fire-resistant covering means can abut against the wall surface of the staircase wall, and the "gap" can be closed, just like in claim 1. In addition, in the invention described in claim 5, an elastic flame-retardant gasket is fixed around the entire circumference of the steel staircase when viewed in a plan view (approximately horizontal direction), and the outer surface of the flame-retardant gasket protrudes outward beyond the outer surface of the fire-resistant covering means, so that the outer surface of the flame-retardant gasket can be abutted against the wall surface of the staircase wall around the entire circumference of the steel staircase with fire-resistant covering means, and the ``gap'' can be more effectively sealed.

[0012] The staircase floor mentioned above refers to a structural member that can support both the upper and lower ends of a normal steel staircase, and also includes steel beams that support the floor. [Effects of the Invention]

[0013] According to this invention of a steel staircase with fire-resistant covering means, the fire-resistant covering means can be fixed to the steel staircase in advance, so the steel staircase with fire-resistant covering means can be manufactured in a factory and delivered to the site. This significantly reduces the work of applying fire-resistant covering after the steel staircase is installed in the staircase room on site. In addition, since a fire-resistant ceiling panel is provided as the fire-resistant covering means, damage to the fire-resistant covering means when the steel staircase with fire-resistant covering means is transported from the factory to the site. Furthermore, if the fire-resistant covering means is formed from a fire-resistant covering material frame, damage to the fire-resistant covering means and the fire-resistant covering work on site can be further reduced. In addition, the fire-resistant covering means is formed by providing a fire-resistant ceiling panel that can cover the underside of the steel staircase, and the outer surface of the fire-resistant covering means is configured to protrude outward from the outer surface of the stringers in a plan view. Therefore, when the steel staircase with fire-resistant covering means is used in a staircase, the outer surface of the fire-resistant covering means can abut against the staircase wall when the steel staircase is stored inside the staircase. This means that flames and smoke from a fire can be blocked or significantly reduced on both sides of the steel staircase with fire-resistant covering means inside the staircase.

[0014] In another invention, a staircase structure includes a steel staircase with fire-resistant covering installed within the staircase, the fire-resistant covering comprising a fire-resistant ceiling panel and fire-resistant covering material that can seal the underside of the steel staircase, the outer surfaces of the fire-resistant covering protruding outward from the outer surfaces of the stringers in a plan view, and elastic flame-retardant gaskets tightly attached between the outer surfaces of both stringers and the staircase walls, minimizing the gap between the staircase walls and the fire-resistant covered steel staircase, significantly reducing the spread of flames and smoke across the fire-resistant covered steel staircase in the event of a fire. Furthermore, elastic flame-retardant gaskets are fixed to the outer surfaces of the stringers and / or the upper surface of the fire-resistant covering, and the outer surfaces of the elastic flame-retardant gaskets protrude outward from the outer edges of the fire-resistant covering, preventing flames and smoke from spreading vertically across the fire-resistant covered steel staircase. [Brief explanation of the drawings]

[0015] [Figure 1](a) is a front view of the steel staircase with fire-resistant coating means of the present invention, (b) is a bottom view of the steel staircase with fire-resistant coating means, and (c) is an AA cross-sectional view of a steel staircase with fire-resistant coating means installed in the staircase wall. [Figure 2] (a) is a cross-sectional view taken along line BB in FIG. 1(b), (b) is a plan view of the fire-resistant covering means used, and (c) is a cross-sectional view taken along line CC. [Figure 3] is an enlarged vertical cross-sectional view showing the relationship between the steel staircase with fire-resistant coating means of this invention and the staircase wall, (a) showing the structure before the steel staircase with fire-resistant coating means is attached to the staircase wall, and (b) showing the structure after the steel staircase with fire-resistant coating means is attached to the staircase wall. [Figure 4] 1 shows a horizontal cross-sectional view of the steel staircase and stairwell with fire-resistant covering means of the present invention applied to an X-shaped staircase. [Figure 5] is a cross-sectional view of the central staircase wall in Fig. 4 taken along the line DD, showing the state of the central staircase wall being transparent. [Figure 6] 4 and 5. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described with reference to the drawings.

[0017] 1. Composition of steel staircase 1

[0018] (1) The steel staircase 1 used in this embodiment of the present invention is similar to a conventional steel staircase. A stair section 6 is composed of plate-shaped steel risers 3 and frame-shaped treads 4 with a predetermined stair width (Fig. 2(a)). A plate-shaped steel upper landing 8 is connected to the upper end of the stair section 6 with a predetermined number of steps, and a plate-shaped steel lower landing 11 is connected to the lower end of the stair section 6 with a predetermined number of steps. The upper landing 8 and lower landing 11 form a landing section 13. The stair section 6 and landing section 13 constructed as described above are fixed to the steel stringers 16, 16 so that they are sandwiched between the inner surfaces 17, 17 of the steel stringers 16, 16 from the left and right. The stringers 16 are fixed to the stair section 6 or landing section 13 by any conventional method, such as welding or bolts and nuts. The steel staircase 1 is constructed by filling the bottomed frame-shaped treads 4, the bottomed frame-shaped upper landing 8, and the lower landing 11 with mortar 21 (cement-based material). Note that the filling of the mortar 21 (cement-based material) can also be done at the construction site after the steel staircase 1 (steel staircase with fire-resistant covering means 32) is installed. Here, the other side of the stringer 16 from the inner surface 17 (the side where the stair section 6 and landing section 13 are located) is referred to as the outer surface (staircase wall side) 17a. Here, the direction connecting both stringers 16, 16 is referred to as the stair width direction.

[0019] (2) A steel fire-resistant coating material frame 24 is formed to match the shape of the underside of the steel staircase 1, i.e., to be able to close and cover the undersides 18 (lower edges) of both stringers 16. The fire-resistant coating material frame 24 is positioned and sized to cover the undersides (lower edges) 18 of the stringers 16 and the entire underside of the staircase section 6 and landing section 13. Note that if the fire-resistant coating material frame 24 is shaped to be able to close and cover the undersides 18 (lower edges) of both stringers 16, it will also necessarily cover the undersides of the staircase section 6 and landing section 13. The fire-resistant covering material frame 24 is formed by two first members 25a, 25a shaped along the underside (lower edge) 18 of the stringer 16 and second members 25b, 25b (in the width direction of the stairs) connecting the first members 25a, 25a at both ends. For reinforcement, any number of third members 25c (in the width direction of the stairs) connecting the first members 25a, 25a, can be added at any position in the middle of the first members 25a (Fig. 2(b)). Furthermore, the upper surface 23a of a fire-resistant ceiling board 23 with a predetermined fire resistance is placed on the underside of the fire-resistant covering material frame 24, and the upper surface 23a of the fire-resistant ceiling board 23 is fixed to the first members 25a and the second members 25b by welding. Therefore, the horizontal outer periphery of the fire-resistant ceiling board 23 in a plan view has the same shape as the first members 25a. Therefore, the horizontal periphery of the fire-resistant ceiling board 23 in a plan view is formed to be approximately the same as the periphery of the first member 25a and the second member 25b in a fixed state. The fire-resistant ceiling board 23 can be made of a steel plate, for example, about 2 mm thick, but the material and thickness can be any as long as it has the fire resistance required for the installation location. Here, the steel plate was used because of its fire resistance, ease of processing, and ease of welding and fixing to the fire-resistant covering material frame 24. Here, the first member 25a and the second member 25b are lipped channel steel (channel steel with a C-shaped cross section) with the groove facing inward of the fire-resistant coating material frame 24 to be formed, and the third member 25c is angle iron (angle iron with an L-shaped cross section). However, as long as the fire-resistant coating material frame 24 can be formed and the required fire resistance performance at the installation location is met, the material and thickness can be any, and the shape of the member to be used can also be any. It is desirable to make the fire-resistant covering material frame 24 out of steel, rather than aluminum or other materials, because of the ease of fixing to the steel stringers 16, ease of processing, and fire and heat resistance. The reason for using lipped channel steel and angle iron to achieve the above shape is that it is easy to assemble into a frame, and, as will be described later, it is easy to install (pack) the fire-resistant rock wool 27 after assembling the frame.

[0020] (3) There are several variations in the method of manufacturing a steel staircase 32 with fire-resistant covering means. Here, we will explain a manufacturing method (combined type) in which the fire-resistant covering means 29 is first constructed and then fixed to the steel staircase 1 to combine them. The first members 25a, 25a and the second members 25b, 25b form a fire-resistant covering material frame 24, and the fire-resistant ceiling board 23 is fixed to its underside. Then, fire-resistant rock wool (fire-resistant covering material) 27 is laid on the upper surface 23a of the fire-resistant ceiling board 23. As the fire-resistant rock wool 27, "Makibee (registered trademark)" (density 60 to 120 kg / m) manufactured by Nichias Corporation is used. 3 ) was arranged to a thickness of 65 mm, but this is not particularly limited. However, a pre-formed fireproof coating material in a roll shape is preferable because it is easy to lay. The first member 25a and the second member 25b are channel steel, and are arranged with the grooves (openings) facing inward. Therefore, the four peripheral edges of the fireproof rock wool 27 are contained within the first member 25a and the second member 25b, and the fireproof rock wool 27 is arranged neatly without coming apart. The fireproof rock wool 27 is fixed to the fireproof ceiling board 23 below with welding pins or the like from the top side of the fireproof rock wool 27. Here, since the fireproof ceiling board 23 and the fireproof coating material frame 24 are fixed, the fireproof rock wool 27 spread and filled in the fireproof coating material frame 24 is held within the fireproof coating material frame 24. At this time, it is preferable to fix the fireproof rock wool 27 to the fireproof ceiling board 23 so as to maintain the original shape of the fireproof rock wool and to minimize compression at the pressed parts. In this way, the fireproof rock wool 27 is packed into the fireproof covering material frame 24 to which the fireproof ceiling board 23 is fixed, thereby forming the fireproof covering means 29 (Figs. 2(b) and (c), Fig. 1(c)).

[0021] (4) The fire-resistant covering material is not limited to fire-resistant rock wool, and fire-resistant sheets, fire-resistant paints, etc. can also be used (not shown) as long as they can exhibit the required fire resistance. For example, when using fire-resistant sheets or fire-resistant paints, the fire-resistant sheets are attached to the upper surface 23a of the fire-resistant ceiling board 23 (and also the lower surface 23b, if necessary), or the fire-resistant paint is applied. Considering fire and heat resistance, application to the upper surface 23a of the fire-resistant ceiling board 23 is desirable. In this case, it is necessary for the fire-resistant sheet or fire-resistant paint to extend to an area on the upper surface 23a of the fire-resistant ceiling board 23 where it abuts the entire lower surface (lower edge) 18 of the stringer 16. Also, if a fire-resistant sheet or fire-resistant paint is used, the fire-resistant coating material frame 24 can be omitted. In this case, the ends of the fire-resistant ceiling board 23 are bent upward and fixed to the outer surface of the stringer 16 by welding (not shown).

[0022] (5) The upper surface 29b of the pre-constructed fire-resistant covering means 29 (i.e., the upper surface of the fire-resistant covering material frame 24, opposite the side on which the fire-resistant ceiling board 23 is placed) is fixed to the lower surface (lower edge) 18 of the stringers 16, 16.

[0023] (6) Furthermore, a resilient, annular (hollow) flame-retardant gasket 30 is disposed on the outer surface 17a of the stringer 16, directly above the fire-resistant covering means 29. The flame-retardant gasket 30 is fixed to the outer surface 17a of the stringer 16, or to the upper surface 29b of the fire-resistant covering means 29, or to both. When the steel staircase 32 with fire-resistant covering means is installed in the staircase 40, the flame-retardant gasket 30 may not be fixed to the outer surface 17a of the stringer 16 as long as it is positioned so as not to move relative to the stringer 16 or the fire-resistant covering means 29 while in contact with the inner surface 43a of the staircase wall 43, the outer surface 17a of the stringer 16, and the fire-resistant covering means 29 (FIGS. 2(b)(c)).The flame-retardant gasket 30 is a construction gasket and can be made of any material and cross-sectional shape as long as it is made of an elastic fire-resistant material.

[0024] (7) In this manner, a steel staircase 32 with fire-resistant covering means is constructed (Figs. 1(a)(b), 2(a)). Here, the outer surface 29a of the fire-resistant covering means 29 (the side surface of the first member 25a) protrudes outward from the outer surface 17a of the stringer 16 in plan view (Figs. 1(a)(b)(c), 3(a)). In addition, the outer peripheral surface (outermost end) 30a of the flame-retardant gasket 30 protrudes outward from the outer surface 29a of the fire-resistant covering means 29 in plan view (Figs. 1(a)(b), 3(a)).

[0025] (8) Although the combined type has been described as a method for manufacturing the steel staircase 32 with the fire-resistant covering means, there is also a manufacturing method (assembly type) in which the fire-resistant covering means 29 is constructed by fixing each component of the fire-resistant covering means 29 (each component of the fire-resistant covering material frame 24, the fire-resistant rock wool 27, the fire-resistant ceiling panel 23, etc.) to the underside of the steel staircase 1 in order. In this method, the assembly procedure is arbitrary, but for example, the first member 25a, second member 25b, and third member 25c of the fire-resistant coating material frame 24 are fixed to the underside of the steel-frame staircase 1, i.e., the underside (lower edge) 18 of the stringer 16, while the members 25a, 25b, and 25c are also fixed to each other to form the fire-resistant coating material frame 24. Then, fire-resistant rock wool 27 is packed into the fire-resistant coating material frame 24 fixed to the underside of the steel-frame staircase 1 (stringer 16), and the rock wool 27 is held within the fire-resistant coating material frame 24. Next, the upper surface 23a of the fire-resistant ceiling board 23 is fixed to the members 25a, 25b, and 25c of the fire-resistant coating material frame 24.

[0026] (9) The differences between the two manufacturing methods result in the following advantages and disadvantages: In the combined type, the steel staircase 1 and the fire-resistant covering means 29 can be assembled separately and stored, simplifying the assembly process. Furthermore, the assembly process for the fire-resistant covering means 29, particularly the fire-resistant covering material frame 24 (first member 25a, second member 25b, third member 25c), is easy, shortening the overall manufacturing time for the steel staircase 32 with fire-resistant covering means. However, because the steel staircase 1 and the fire-resistant covering means 29 each have some manufacturing tolerances, combining the two may magnify the manufacturing tolerances, requiring significant time for correction. Furthermore, in the assembly type, each component 25a, 25b, and 25c of the fire-resistant coating material frame 24, cut to size, is individually attached to the steel staircase 1, so even if there is some manufacturing error, the fire-resistant coating material frame 24 can be constructed by using the steel staircase 1 as a ruler and making fine adjustments each time. This allows for high manufacturing accuracy in the finished steel staircase 32 with fire-resistant coating means. However, in the assembly type, because the steel staircase 32 with fire-resistant coating means is manufactured by attaching and fine-tuning each component, it takes more time to manufacture than the combined type. Both manufacturing methods have their advantages and disadvantages, but it is expected that a lot of work will be required in the process of correcting manufacturing errors, and in the current situation, the assembly type may be more appropriate.

[0027] 2. Staircase structure

[0028] (1) In a building with a stairwell 40, a steel staircase 32 with fire-resistant covering means is erected and fixed between the reference floor (stairwell floor) 46 and the floor below (stairwell floor) 48 (Fig. 1(a)), Fig. 2(a)). Note that the reference floor 46 here represents any general floor, and can be the ground floor, second floor, basement floor, etc. In this case, the outer surface 29a of the fire-resistant covering means 29 protrudes outward beyond the outer surface 17a of the stringer 16, so the outer surface 29a of the fire-resistant covering means 29 abuts or is positioned very close (sometimes leaving a very small gap) to the inner surface 43a of the staircase wall 43. In addition, because the outer peripheral surface (outermost end) 30a of the flame-retardant gasket 30 protrudes outward beyond the outer surface 29a of the fire-resistant covering means 29 and the flame-retardant gasket 30 is made of an elastic material, the flame-retardant gasket 30 is sandwiched between the outer surface 17a of the stringer 17 and the inner wall surface 43a of the staircase wall 43, and is crushed and deformed, thereby sealing the gap between the outer surface 17a of the stringer 17 and the inner wall surface 43a of the staircase wall 43 (Figs. 1(c) and 3(b)). Therefore, even if a gap occurs between the outer surface of the fire-resistant coating means 29 (fire-resistant coating material frame 24) of the steel staircase 32 with fire-resistant coating means and the inner wall surface 43a of the staircase wall 43, the flame-retardant gasket 30 can absorb this gap and adhere to the inner wall surface 43a of the staircase wall 43.

[0029] (2) Similarly, on the side of the reference floor 46 and the floor below 48, the tip 29d of the fire-resistant covering means 29 in the stair walking direction 38 protrudes outward from the tip 1a (so-called baseboard portion, outer surface) of the steel staircase 1 of the steel staircase with fire-resistant covering means 32, so that the tip 29d of the fire-resistant covering means 29 is disposed in contact with or very close proximity to the reference floor 46 (or the floor below 48) (sometimes leaving a very small gap). In this case, the outer peripheral surface (outermost end) 30a of the flame-retardant gasket 30 protrudes outward from the outer surface 29a of the fire-resistant covering means 29, and because the flame-retardant gasket 30 is made of an elastic material, the flame-retardant gasket 30 is sandwiched between the reference floor 46 (or the floor below 48) and is crushed and deformed, thereby sealing the gap between the tip 1a of the steel staircase 1 and the reference floor 46 (or the floor below 48) (not shown).

[0030] (3) In this way, within the staircase 40, the outer surface of the flame-retardant gasket is arranged around the entire periphery of the steel staircase 32 with fire-resistant coating means, with the outer surface of the flame-retardant gasket in close contact with the wall of the staircase, or with the reference floor 46 or the floor 48 below.

[0031] (4) When walking up the steel staircase with fire-resistant covering means 32, the underside of the steel staircase with fire-resistant covering means 32 located above is visible, but because the fire-resistant ceiling board 23 is arranged on the underside of the steel staircase with fire-resistant covering means 32, i.e., on the underside 29c of the fire-resistant covering means 29, only the underside 23b of the fire-resistant ceiling board 23 is exposed, and the fire-resistant rock wool 27 and the like are not visible, so the appearance is not impaired. Furthermore, because the underside 23b of the fire-resistant ceiling board 23 is flat, this flat surface can be used to display various guide signs (for example, displaying the floor numbers of upper floors) according to the location of the steel staircase with fire-resistant covering means 32, or a display (not shown) can be installed.

[0032] (5) Furthermore, according to experiments, with this configuration, even when the area directly below the steel staircase 32 with fire-resistant covering means (directly below the fire-resistant ceiling panel 23) is burned for one hour (60 minutes) using a gas burner or the like to rapidly raise the temperature and heat it to a final temperature of approximately 940°C, flames and smoke do not reach the top of the steel staircase 32 with fire-resistant covering means, and it has been confirmed that the steel staircase 32 with fire-resistant covering means can be fully used as a one-hour fire-resistant staircase. Therefore, by adjusting the thickness of the fire-resistant ceiling board 23, the configuration and thickness of each component 25a, 25b, 25c of the fire-resistant coating material frame 24 (especially the number of third components 25c), and the thickness and amount of rock wool 27, it is possible to achieve not only 1-hour fire resistance but also 90-minute and 120-minute fire resistance.

[0033] 3. Configuration of stairwell for X-staircase

[0034] (1) Like the normal stairwell 40, the stairwell 40 for the X-type staircase is surrounded by stairwell walls 43 (stairwell walls 43A, 43B). Here, a central stairwell wall 45 is provided within the stairwell 40, between and parallel to the stairwell walls 43A, 43B (parallel to the stair walking direction 38). The stairwell 40 is divided vertically by the central stairwell wall 45 into two series of compartments: a first compartment A and a second compartment B (Figure 4). Furthermore, the wall surface of the central stairwell wall 45 facing the first compartment A is referred to as inner wall 45a, and the wall surface facing the second compartment B is referred to as inner wall 45b.

[0035] (2) On one side 46a of the standard floor (staircase floor) 46, an upward steel staircase 32A with first fire-resistant covering means is erected in the first section A toward the other side 49b of the upper floor (staircase floor) 49, and a downward steel staircase 32B with second fire-resistant covering means is erected in the second section B toward the other side 48b of the lower floor (staircase floor) 48 (Figs. 5 and 6). Similarly, on the other side 46b of the standard floor 46, a downward steel staircase 32A with first fire-resistant covering means is erected in the first section A toward the other side 48a of the lower floor 48, and an upward steel staircase 32B with second fire-resistant covering means is erected in the second section B toward the other side 49a of the upper floor 49 (Figs. 5 and 6). Therefore, in this embodiment, the first steel staircase with fire-resistant covering means 32A and the second steel staircase with fire-resistant covering means 32B are arranged in a cross shape on the same floor.

[0036] (3) In this case, in the first section A, the outer surface 29a of the fire-resistant covering means 29 of each steel staircase 32A with first fire-resistant covering means protrudes outward beyond the outer surface 17a of the stringer 16, so that at the step chamber wall 43A, the outer surface 25a of the fire-resistant covering material frame 24 of the fire-resistant covering means 29 of the steel staircase 32A with first fire-resistant covering means abuts or is close to the inner wall surface 43Aa of the step wall 43A, and the flame-retardant gasket 30 is in tight contact with the inner wall surface 43Aa of the step wall 43A. Similarly, at the central staircase wall 45, the outer surface 25a of the fire-resistant covering material frame 24 of the fire-resistant covering means 29 of the steel staircase 32A with first fire-resistant covering means abuts or is close to the inner wall surface 45a of the step wall 45, and the flame-retardant gasket 30 is in tight contact with the inner wall surface 45a of the step wall 45. Similarly, in the second section B, in each steel staircase with second fire-resistant covering means 32B, the outer surface 29a of the fire-resistant covering means 29 protrudes outward beyond the outer surface 17a of the stringer 16, so that in the step chamber wall 43B, the outer surface 25a of the fire-resistant covering material frame 24 of the fire-resistant covering means 29 of the steel staircase with second fire-resistant covering means 32B abuts or is close to the inner wall surface 43Ba of the step chamber wall 43B, and the flame-retardant gasket 30 is in tight contact with the inner wall surface 43Ba of the step chamber wall 43B. Similarly, in the central staircase wall 45, the outer surface 25a of the fire-resistant covering material frame 24 of the fire-resistant covering means 29 of the steel staircase with second fire-resistant covering means 32B abuts or is close to the inner wall surface 45b of the step wall 45, and the flame-retardant gasket 30 is in tight contact with the inner wall surface 45b of the step wall 45. Also, on the floor side, such as the standard floor 46 (46a, 46b), as with the normal staircase 40, the steel staircases 32A, 32B with fire-resistant coating means are also tightly attached to the standard floor 46 (46a, 46b) by the tip 25d of the fire-resistant coating material frame 24 and further by the flame-retardant gasket 30 (not shown).

[0037] (4) Therefore, even in the case of the X-type staircase, it is considered that the steel staircase 32 with fire-resistant covering means (steel staircase 32A with first fire-resistant covering means, steel staircase 32B with second fire-resistant covering means) can be sufficiently used as a one-hour fire-resistant staircase. Therefore, in the event of a fire, even if either the first compartment A or the second compartment B on one of the floors of the stairwell is filled with smoke, it is possible to safely evacuate using the stairs in the other compartment.

[0038] (5) Furthermore, in the X staircase, the vertical distance between tread 4 (stair section 6) of steel staircase 32A with first fire-resistant covering means (steel staircase 32B with second fire-resistant covering means) and the underside of the steel staircase 32A with first fire-resistant covering means (steel staircase 32B with second fire-resistant covering means) located above (i.e., underside 29c of fire-resistant covering means 29, underside of fire-resistant ceiling board 23) is shorter than in the case of a steel staircase placed in a normal stairwell (Figure 5), so a person walking on tread 4 (stair section 6) will recognize the underside of steel staircase 32A with first fire-resistant covering means (steel staircase 32B with second fire-resistant covering means) as being close to overhead. In this case too, in a normal X-shaped staircase, the underside of the staircase portion 6 of the steel staircase can be seen up close by a pedestrian, but in this embodiment, the underside of the steel staircase 32A with first fire-resistant covering means (steel staircase 32B with second fire-resistant covering means) located above is located under the fire-resistant ceiling board 23, so only the flat surface of the fire-resistant ceiling board 23 can be seen, and the effect of the fire-resistant ceiling board 23 in not impairing the appearance is demonstrated more than in the case of the normal staircase 40.

[0039] 4. Other Embodiments

[0040] (1) In the above embodiment, the fire-resistant covering material frame 24 is configured by the first member 25a, the second member 25b, and the third member 25c, but other configurations (not shown) are also possible as long as they are configured in a frame shape. Furthermore, if the fire-resistant ceiling board 23 and the fire-resistant rock wool 27 can be fixed to the underside of the steel-frame staircase 1 (the underside of the stringer 16), the fire-resistant covering material frame 24 can be omitted and the fire-resistant covering means 29 can be configured (not shown).

[0041] (2) In the above embodiment, if both ends 1a, 1a (so-called baseboard parts, outer surfaces; Figures 1(a) and 2(a)) of the steel staircase 1 used for each steel staircase with fire-resistant covering means 32, 32A, 32B in the stairway walking direction 38 can be fixed in close contact with each floor (reference floor 46, lower floor 48, lower floor 49), the edge 29d of the fire-resistant covering means 29 (i.e., the outer surface of the second member 25b; Figures 1(a) and 1(b))) can be prevented from protruding from the end 1a in the stairway walking direction 38. Furthermore, in this case, the flame-retardant gasket 30 can be omitted on the surfaces of both ends 1a, 1a of the steel staircase 1 in the stairway walking direction 38 (so-called baseboard parts, i.e., the surfaces on the edge 29d side of the fire-resistant covering means 29 and the outer surface side of the second member 25b). In other words, in this case, the tip 29a of the fire-resistant coating means 29 protrudes from the outer surface 17a of the stringer 1 only on the stringer 16 side, or the outer surface 30a of the flame-retardant gasket 30 protrudes from the outer surface of the stringer 1 only on the stringer 16 side.

[0042] (3) In the above embodiment, the flame-retardant gasket is annular (hollow) to ensure greater elasticity, but it can also be a solid rod (not shown).Similarly, the cross-sectional outer shell shape is assumed to be circular, but it can also be other shapes such as a rectangle (not shown). [Explanation of symbols]

[0043] 1 Steel Staircase 1a Tip of steel staircase (baseboard part, outer surface) 3. Riser board (riser part) 4 Step board (step board part) 6 Stairs section 8 Upper landing (landing part) 11 Lower landing (landing part) 13 Landing area 16 Stringers 17 Inside of stringer 17a Outer surface of stringer 18 Underside of stringer (lower edge) 21 Mortar (cement-based materials) 23 Fireproof ceiling board 23a Upper surface of fireproof ceiling board 23b Underside of fireproof ceiling board 24 Fireproof coating material frame 25a First member (fire-resistant covering material frame) 25b Second member (fire-resistant covering material frame) 25c Third member (fire-resistant covering material frame) 25d Tip of fire-resistant coating material frame 27 Fireproof rock wool (fireproof coating material) 29 Fireproof coating means 29a Outer surface of fire-resistant covering means 29b Upper surface of fire-resistant covering means 29c Underside of fire-resistant covering means 29d Tip of fire-resistant covering means 30 Flame-retardant gasket 30a Outer surface of flame-retardant gasket 32 Steel stairs with fire-resistant covering 32A Steel staircase with first fire-resistant covering means 32B Steel staircase with first fire-resistant covering means 38 Stair walking direction 40 Staircase 43, 43A, 43B Staircase wall 43a, 43Aa, 43Ba Inner surface of staircase wall 45 Central staircase wall 45a, 45b Central staircase wall 46 Standard floor (staircase floor) 46a One side of the standard floor 46b Other side of the reference floor 48 Lower floor (staircase floor) 48a One side of the lower floor 48b Other side of lower floor 49 Upper floor (stairwell floor) 49a One side of the upper floor 49b Other side of upper floor A First Section B Second Section

Claims

1. A steel staircase with fire-resistant covering means is formed on a steel staircase constructed by sandwiching "step-like treads" or "step-like treads and landing portions" between the inside surfaces of steel stringers, and is characterized by being configured as follows. (1) The fire-resistant covering means is configured by disposing a fire-resistant covering material between the upper surface of a fire-resistant ceiling board that can cover the underside of the steel staircase and the underside of the steel staircase. (2) The outer surface of the fire-resistant covering means on the side of the stringer protrudes outward in a plan view from the outer surface of the stringer.

2. 2. A steel staircase with fire-resistant covering means according to claim 1, which is configured as follows: (1) The fire-resistant covering means is configured by fixing a fire-resistant ceiling board having a shape that follows the outer surface of the fire-resistant covering material frame in a plan view to the underside of a fire-resistant covering material frame that covers the underside of the steel staircase and follows the underside of both stringers in a plan view, and filling the fire-resistant covering material frame with fire-resistant rock wool. (2) The fire-resistant coating material frame of the fire-resistant coating means was fixed to the underside of the stringer.

3. 3. A steel staircase with fire-resistant covering means according to claim 2, which is configured as follows: (1) The underside of the stringer of the steel staircase and the top surface of the steel fire-resistant coating material frame, and the top surface of the steel fire-resistant coating material frame and the top surface of the steel fire-resistant ceiling panel were welded together.

4. 2. A steel staircase with fire-resistant covering means according to claim 1, which is configured as follows: (1) An elastic fire-retardant gasket is fixed to the upper surface of the fire-resistant covering means and to the outer surfaces of both stringers. (2) The outer peripheral surface of the flame-retardant gasket protrudes outward in plan view from the outer surface of the fire-resistant covering means.

5. 5. A steel staircase with fire-resistant covering means according to claim 4, which is configured as follows: (1) The entire circumference of the fire-resistant covering means protrudes outward from the outer surface of the steel staircase in the horizontal direction when viewed in plan, all around the steel staircase. (2) An elastic flame-retardant gasket is fixed to the upper surface of the fire-resistant covering means around the entire periphery of the steel staircase in a plan view. (3) The outer peripheral surface of the flame-retardant gasket protrudes outward beyond the outer surface of the fire-resistant covering means.

6. A staircase structure spanning upper and lower floors, partitioned by staircase walls of a specified fire-resistant construction and equipped with a staircase floor of a specified fire-resistant construction, in which a steel staircase with fire-resistant covering means is erected between the staircase floor located above on one side of the staircase walking direction and the staircase floor located below on the other side, and which is configured as follows. (1) The fire-resistant covering means is configured by disposing a fire-resistant covering material between the upper surface of a fire-resistant ceiling board that can cover the underside of the steel staircase and the underside of the steel staircase. (2) The outer surface of the fire-resistant covering means protrudes outward in a plan view from the outer surface of the stringer, and the outer surface of the fire-resistant covering means abuts against the wall surface of the staircase wall or is positioned in a position near the wall surface of the staircase wall. (3) An elastic flame-retardant gasket is attached to the upper surface of the fire-resistant covering means between the outer surfaces of the stringers and the wall surface of the staircase wall, and the flame-retardant gasket is arranged on the outer surfaces of the stringers over the entire length in the direction of stair walking.

7. 7. The staircase structure according to claim 6, characterized in that it is configured as follows: (1) A central staircase wall is placed approximately in the center of the staircase wall in the direction of stairway walking, and the building is divided vertically into two sections, a first section and a second section, with the central staircase wall as the dividing line. A steel staircase with a first fire-resistant covering means is erected in the first section, and a steel staircase with a second fire-resistant covering means is erected in the second section, and the first steel staircase with a fire-resistant covering means and the second steel staircase with a fire-resistant covering means are arranged crosswise on the same floor. (2) In the steel staircase with the first fire-resistant covering means and the steel staircase with the second fire-resistant covering means, the outer surfaces of the fire-resistant covering means protrude outward in a plan view from the outer surfaces of the stringers, and the outer surfaces of the fire-resistant covering means abut against the wall surfaces of the staircase walls and the central staircase wall, or are positioned in the vicinity of the wall surfaces of the staircase walls. (3) In the steel staircase with the first fire-resistant covering means and the steel staircase with the second fire-resistant covering means, in the first section and the second section, elastic flame-retardant gaskets are tightly attached to the upper surface of each fire-resistant covering means, between the outer surface of the stringer and the wall surface of the central staircase wall, and between the outer surface of the stringer and the wall surface of the staircase wall, and the flame-retardant gaskets are arranged on the outer surface of each stringer over the entire length of the staircase in the direction of walking.

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