JP6738523B2 - Steel stairs and method of mounting steel stairs - Google Patents

Description

The technology disclosed herein relates to steel stairs.

A steel frame staircase is known which is attached between a frame on the upper floor and a frame on the lower floor of a structure such as a building or a civil engineering structure (see, for example, Patent Document 1). Generally, a steel frame staircase is provided with a lower fixing part having a through hole into which an anchor bolt fixed to a lower body is inserted. For example, the lower fixing portion is provided inside and outside the girder portion of the steel staircase. When installing steel stairs, make a recess in the floor on the lower floor and install the lower fixing part in the recess so that the anchor bolt protruding from the bottom of the recess is inserted into the through hole formed in the lower fixing part. Then, the lower fixing part is fixed with a nut, and concrete is poured into the concave part. As a result, the floor surface becomes flat, and the lower fixing portion provided outside the girder portion of the steel-frame staircase is covered with concrete, which facilitates storage.

JP, 2002-294959, A

When a recess is provided on the floor of the lower floor as in the above-mentioned conventional technique, a step is generated on the floor of the lower floor, and therefore it is necessary to perform step reinforcement for adding reinforcement such as step beams. Further, in order to fill the recess and flatten the floor surface, it is necessary to additionally perform floor reinforcement of the recess, concrete pouring, and the like. Therefore, there is a problem that the labor and cost required for mounting the steel stairs increase.

The present specification discloses a technique capable of solving at least a part of the above-mentioned problems.

(1) The steel frame staircase disclosed in the present specification is a steel frame staircase that is attached between a frame on the upper floor of a structure and a frame on the lower floor, and includes a pair of girder parts and a pair of girder parts. A plurality of treads supported between, an upper fixing portion that fixes the pair of girder portions to the upper floor body, and a lower fixing portion that fixes the pair of girder portions to the lower floor body, A lower fixing portion that is located between the pair of girder portions and has a through hole into which the anchor bolt protruding from the floor surface of the lower floor is inserted. According to this steel staircase, since the lower fixing part is fixed to the anchor bolt protruding from the floor of the lower floor, the lower fixing part is fixed to the anchor bolt on the floor of the lower floor. Since the fixing part is arranged between the pair of girders, the lower fixing part fixed to the anchor bolt does not protrude from the floor surface of the lower floor outside the pair of girders, and the lower part of the steel stairs is not damaged. You can make it better. Therefore, it is not necessary to provide a recess in the lower frame to cover the lower fixing portion, and it is possible to suppress the labor and cost required for mounting the steel stairs.

(2) In the steel frame staircase, the lower fixing portion may be arranged below the tread. According to the steel frame stairs, the lower fixing portion can be covered with the treads, and the storage around the lower part of the steel frame stairs can be improved.

(3) In the steel frame staircase, the tread plate located above the lower fixing portion is provided with an opening penetrating in the vertical direction, and the steel frame staircase further has a lid portion that opens and closes the opening. It may be configured. According to this steel frame staircase, the worker who installs and fixes the lower fixing part to the body of the lower floor installs the anchor bolt while visually observing the anchor bolt through the opening from above the tread, and then installing the nut through the opening. Fixing work such as tightening can be performed, and the labor required for attaching the steel frame stairs can be suppressed. Further, according to the present steel staircase, since it has a lid that opens and closes the opening, when using the steel staircase, by closing the opening with the lid, a user who uses the steel staircase can safely carry out the steel staircase. Can be used.

(4) In the above-mentioned steel-frame staircase, further, a plurality of riser plates supported between the pair of girder portions are provided, and the lower fixing portion is the lowermost step plate arranged at the lowermost of the plurality of step plates. It is good also as a structure arrange|positioned rather than the lowermost riser board arrange|positioned between the floor surface of the said lower floor, and the ascending side of the said steel frame stairs. According to the present steel staircase, it is possible to cover the lower fixing portion by using the riser plate, and it is possible to further improve the fit around the lower portion of the steel staircase.

(5) In the steel frame staircase, the lower fixing portion is fixed to a surface of one of the pair of girder portions on the other girder portion side, is arranged substantially parallel to the tread plate, and is penetrated. A first lower fixing part having a first flat surface part in which a hole is formed, and a first girder part side surface of the other girder part of the pair of girder parts, the part being substantially parallel to the tread plate. It may be configured to include a second lower fixing portion that is disposed and has a second flat surface portion in which the through hole is formed. According to the steel frame staircase, one of the pair of girders can be fixed to the frame of the lower floor by using the first lower fixing part, and the pair of girder parts can be fixed by using the second lower fixing part. The other girder part of the above can be fixed to the frame of the lower floor.

(6) In the steel staircase, the lower fixing portion may be arranged below the lowermost tread plate, which is the lowermost tread plate among the plurality of tread plates. According to this steel staircase, the length of the anchor bolt that needs to be exposed from the floor surface of the lower floor is shortened as compared with the case where the lower fixing part is arranged at the same height as or higher than the first tread. Therefore, the labor and cost required for mounting the steel stairs can be suppressed.

(7) The technology disclosed in this specification can be realized in various forms, for example, a method of manufacturing a steel staircase, a method of attaching a steel staircase, and the like. is there. The method of attaching the steel stairs disclosed in the present specification is a method of attaching the steel stairs between the upper and lower skeletons of the structure, and from the floor of the lower floor. Installation in which the protruding anchor bolt is installed with respect to the skeleton on the lower floor so that the protruding anchor bolt is inserted into a through hole formed in a lower fixing portion located between a pair of girder portions of the steel frame staircase. And a fixing step of fixing the lower fixing portion to the anchor bolt.

Explanatory drawing which shows roughly the structure of the building 1 to which the steel-frame stairs 10 were attached. Explanatory drawing which shows roughly the connection structure of the steel frame stairs 10 and the beam 60. The top view which shows roughly the connection structure of the steel frame stairs 10 and the floor 50. Sectional drawing which shows schematically the connection structure of the steel frame stairs 10 and the floor 50. Front view of steel stairs 10 Rear view of steel staircase 10 Top view of steel stairs 10 Bottom view of steel stairs 10 Right side view of steel stairs Left side view of the steel stairs 10

A. Embodiment:
A-1. Construction of the steel stairs 10:
FIG. 1 is an explanatory diagram schematically showing a part of the structure of a building 1 to which a steel staircase 10 according to the present embodiment is attached. In FIG. 1, illustration of a part of the finish of the building 1 is omitted. The building 1 is a steel-framed two-story building, and the steel stairs 10 is attached between the beam 60 on the second floor of the building 1 and the floor 50 on the first floor of the building 1. The beam 60 is an example of a frame on the upper floor, and the floor 50 is an example of a frame on the lower floor. FIG. 1 shows XYZ axes that are orthogonal to each other for specifying a direction. In the present specification, for convenience, the X-axis positive direction is called the right direction, the X-axis negative direction is called the left direction, the Y-axis positive direction is called the front direction, the Y-axis negative direction is called the rear direction, and Z is The positive direction of the axis is called the upward direction, and the negative direction of the Z axis is called the downward direction. The same applies to FIG. 2 and subsequent figures.

As shown in FIG. 1, the steel staircase 10 includes a pair of girder portions 30 and a step plate portion 20. The pair of girder portions 30 includes a first girder portion 30A arranged on the right side of the step plate portion 20 and a second girder portion 30B arranged on the left side of the step plate portion 20. The first girder portion 30A and the second girder portion 30B are made of steel plates. The first girder portion 30A and the second girder portion 30B include a girder central portion 36 obliquely arranged from the rear lower side to the front upper side, and a girder portion extending forward from the upper end of the girder central portion 36. It has an upper part 32 and a girder lower part 38 extending rearward from the lower end of the girder central part 36. The lower end surface of the lower girder portion 38 is in contact with the floor surface FL of the floor 50.

Each upper girder portion 32 functions as an upper fixing portion that fixes the corresponding girder portion 30 to the beam 60. FIG. 2 is an explanatory view schematically showing a connection structure between the steel frame stairs 10 and the beam 60. As shown in FIG. 2, two through holes 34 into which two bolts 66 can be inserted are formed in the upper portion 32 of the girder portion 30 of the girder portion 30. A mounting plate 62 is fixed to the beam 60 by welding or the like, and two long holes 64 into which two bolts 66 can be inserted are formed in the mounting plate 62. In the steel staircase 10 of the present embodiment, when the girder upper portion 32 is fixed to the beam 60, bolts 66 are inserted into the long holes 64 and the through holes 34 and fixed by tightening nuts or the like. As a result, the girder upper portion 32 and the beam 60 are fixed so as to be movable in the Y-axis direction.

FIG. 3 is a top view schematically showing the connection structure between the steel frame stairs 10 and the floor 50, and FIG. 4 is a sectional view taken along the line IV-IV in FIG. As shown in FIGS. 3 and 4, each girder lower part 38 is provided with a lower fixing part 40 for fixing the corresponding girder 30 to the floor 50. The lower fixing portion 40 is composed of a first lower fixing portion 40A and a second lower fixing portion 40B. The first lower fixing portion 40A is welded to the surface of the first girder portion 30A on the second girder portion 30B side (left side) so as to be substantially parallel to the lowermost step plate 21X described later. Further, the second lower fixing portion 40B is joined by welding to the surface of the second girder portion 30B on the first girder portion 30A side (right side) so as to be substantially parallel to the lowermost step plate 21X. That is, the lower fixing portions 40A and 40B are arranged on the second girder portion 30B side with respect to the first girder portion 30A and on the first girder portion 30A side with respect to the second girder portion 30B, that is, the pair of girder portions 30 in the left-right direction. Is disposed only inside the first girder portion 30A, on the opposite side to the second girder portion 30B with respect to the first girder portion 30A, and on the opposite side to the first girder portion 30A with respect to the second girder portion 30B, that is, a pair of It is not arranged outside the girder portion 30. The first lower fixing portion 40A is an example of a first flat surface portion, and the second lower fixing portion 40B is an example of a second flat surface portion.

Two through holes 42 are formed in the first lower fixing portion 40A, and two through holes 42 are formed in the second lower fixing portion 40B. An anchor bolt 52 is embedded in a floor 50 on which the steel staircase 10 is installed, and a tip of the anchor bolt 52 projects above the floor surface FL. In the steel staircase 10 of the present embodiment, when fixing the first lower fixing portion 40A and the second lower fixing portion 40B to the floor 50, two of the four anchor bolts 52 are two of the first lower fixing portion 40A. The remaining two are inserted into the through holes 42, and the remaining two are inserted into the two through holes 42 of the second lower fixing portion 40B. Then, the washer 45 is inserted into the anchor bolt 52 protruding upward from the through hole 42, and screwed into the screw thread of the anchor bolt 52 from above the first lower fixing portion 40A and the second lower fixing portion 40B through the washer 45. The nut 44 and the nut 46 that is screwed into the thread of the anchor bolt 52 from below the first lower fixing portion 40A and the second lower fixing portion 40B to the first lower fixing portion 40A and the second lower fixing portion 40B. The first lower fixing portion 40A and the second lower fixing portion 40B are fixed to the anchor bolt 52 by tightening against each other.

Next, the step plate portion 20 will be described. The step plate portion 20 is formed of a steel plate, and is joined by welding between the pair of girder portions 30 as shown in FIG. 1. The step plate portion 20 has a plurality of step plates 21 provided substantially horizontally, and a plurality of riser plates 22 provided with the upper side inclined rearward with respect to the vertical. The plurality of treads 21 are diagonally arranged at equal intervals. The plurality of riser plates 22 are arranged between the tread plates 21 adjacent to each other. It should be noted that one of the plurality of riser plates 22 is arranged between the lowermost step plate 21X of the plurality of step plates 21 arranged at the lowermost position and the floor 50. Hereinafter, the riser plate 22 arranged between the lowermost step plate 21X and the floor 50 is referred to as the lowermost riser plate 22X.

In the longitudinal direction of the lowermost step plate 21X, that is, at both ends in the left-right direction, openings 24 are formed to penetrate the lowermost step plate 21X in the vertical direction. Further, the steel frame staircase 10 has a lid portion 28 that opens and closes the opening 24. The opening 24 includes a first opening 24A provided at the right end of the lowermost step plate 21X and a second opening 24B provided at the left end of the lowermost step plate 21X. The lid portion 28 includes a first lid portion 28A that opens and closes the first opening 24A and a second lid portion 28B that opens and closes the second opening 24B. The first lid portion 28A is attached to the right side edge of the first opening 24A by the first hinge 26A. The second lid portion 28B is attached to the left side edge of the second opening 24B by the second hinge 26B. In addition, the upper surfaces of the plurality of treads 21 including the bottom tread 21X are covered with a finishing material after the steel frame stairs 10 are attached to the building 1. Therefore, even if the openings 24A and 24B are formed in the lowermost step plate 21X and the openings 24A and 24B are covered with the lid portions 28A and 28B, the appearance of the steel staircase 10 is not deteriorated.

Next, the positional relationship between the lower fixing portions 40A and 40B and the step plate portion 20 will be described. As shown in FIG. 3, the lower fixing portions 40A and 40B are arranged in the forward direction of the lowermost riser plate 22X, that is, on the rising side of the steel frame stairs 10. Further, as shown in FIGS. 3 and 4, the lower fixing portions 40A and 40B are arranged below the lowermost step plate 21X, specifically, below the openings 24A and 24B provided in the lowermost step plate 21X. Has been done.

A-2. How to attach the steel stairs:
Next, a method of attaching the steel frame stairs 10 between the beams 60 and the floor 50 of the building 1 (hereinafter, simply referred to as “attachment method”) will be described. In the attachment method of this embodiment, the installation step and the fixing step are performed in this order. Hereinafter, each step will be described.

(Installation process)
In the attachment method of this embodiment, the installation step is first performed. In the installation step, the steel frame stairs 10 are installed so that the four anchor bolts 52 protruding from the floor surface FL of the floor 50 are inserted into the through holes 42 formed in the lower fixing portions 40A and 40B. .. In the installation step, the lower fixing parts 40A and 40B are installed with the lid parts 28A and 28B provided on the lowermost step plate 21X of the steel staircase 10 being opened. Thereby, the worker who executes the installation step can install the steel frame stairs 10 while visually observing the anchor bolt 52 and the lower fixing portions 40A and 40B from the upper side of the tread 21 through the openings 24A and 24B.

The diameter of each through hole 42 is larger than the diameter of the corresponding anchor bolt 52. Therefore, even when there is an error in the installation position of the anchor bolt 52, the error can be absorbed by the difference between the diameter of each through hole 42 and the diameter of the corresponding anchor bolt 52 to install the steel staircase 10. it can.

(Fixing process)
Next, a fixing process is performed. In the fixing step, the washer 45 is inserted into the anchor bolt 52 protruding upward from the through hole 42, and the nut 44 that is screwed into the screw thread of the anchor bolt 52 from above the lower fixing portions 40A and 40B and the lower fixing portion 40A. The lower fixing portions 40A and 40B are fixed to the anchor bolt 52 by tightening a nut 46 that is screwed onto the thread of the anchor bolt 52 from below 40B to the lower fixing portions 40A and 40B. As a result, the steel staircase 10 is fixed to the floor 50. In the fixing step, the anchor bolt 52 is tightened with the nuts while the lids 28A and 28B provided on the lowermost step plate 21X of the steel staircase 10 are opened. Thereby, the worker who performs the fixing step can tighten the nut from the upper side of the tread 21 through the openings 24A and 24B.

A-3. Design description:
5 to 10 show a steel frame staircase 10, which is an article related to a design. The article is a steel staircase 10 mounted between the upper and lower skeletons of a structure. As shown in FIG. 1 and the like, the present article includes a pair of girder portions 30 and a step plate portion 20, and lower fixing portions 40A and 40B formed between the pair of girder portions 30 provide a floor surface of a lower floor. It is fixed to the anchor bolt 52 protruding from. As shown in FIG. 3, the lower fixing portions 40A and 40B are arranged between the lowermost tread 21X arranged at the lowermost of the plurality of treads 21 included in the step plate 20 and the floor surface of the lower floor. It is arranged on the ascending side of the steel frame stairs 10 with respect to the lowermost riser plate 22X, and as shown in FIG. 4, is arranged below the lowermost step plate 21X. The lower fixing portions 40A and 40B are flat plates formed of steel plates and are arranged so as to be substantially parallel to the lowermost step plate 21X. Two through holes 42 into which two of the four anchor bolts 52 are inserted are formed in the lower fixing portions 40A and 40B, respectively. In addition, in FIGS. 5 to 10, a portion indicated by a solid line is a design which is to be registered as a partial design.

As described above, in the steel staircase 10 of the present embodiment, the lower fixing portions 40A and 40B are fixed to the anchor bolts 52 protruding from the floor surface FL of the floor 50. Therefore, the lower fixing portions 40A and 40B are fixed to the anchor bolt 52 on the floor surface FL. In the steel staircase 10 of the present embodiment, the lower fixing portions 40A and 40B are arranged only inside the pair of girder portions 30, and the members including the subfixing fixing portions 40A and 40B are present outside the pair of girder portions 30. Therefore, even if the lower fixing portions 40A and 40B are fixed to the anchor bolts 52 on the floor surface FL, it is possible to improve the fit around the lower portion of the steel staircase 10. Therefore, it is not necessary to provide a recess in the floor 50 to cover the lower fixing portions 40A and 40B. For example, in the case where the floor 50 is made of reinforced concrete, in order to provide a recess in the floor 50, it is necessary to carry out step reinforcement to add reinforcement such as step beams to generate a step in the floor 50. Further, in order to fill the recess and flatten the floor 50, it is necessary to additionally perform floor reinforcement of the recess, concrete pouring, and the like. Therefore, the labor and cost required for mounting the steel frame stairs 10 increase. In the steel-frame staircase 10 of this embodiment, since it is not necessary to provide a recess, it is possible to suppress the labor and cost required for mounting the steel-frame staircase 10.

The lower fixing portions 40A and 40B are arranged below the lowermost step plate 21X. Therefore, it is possible to cover the lower fixing portions 40A and 40B by using the lowermost step plate 21X, and it is possible to improve the fit around the lower portion of the steel staircase 10. Further, since the lower fixing portions 40A, 40B are arranged below the lowermost step plate 21X, compared to the case where the lower fixing portions 40A, 40B are arranged at the same height as or above the lowermost step plate 21X. The length of the anchor bolt 52 protruding from the surface FL can be shortened, and the labor and cost required for mounting the steel staircase 10 can be suppressed.

The lowermost step plate 21X is provided with openings 24A and 24B that penetrate vertically. Therefore, an operator who installs and fixes the lower fixing portions 40A and 40B on the floor 50 installs the anchor bolt 52 from above the tread 21 through the openings 24A and 24B while visually observing the openings 24A and 24B. Fixing work such as nut tightening can be performed via the. Therefore, the worker can suppress the labor required for attaching the steel frame stairs 10 as compared with the case where the worker dives under the tread 21 to perform the work.

The lower fixing portions 40A and 40B are arranged on the rising side of the steel frame stairs 10 with respect to the lowermost riser plate 22X. Therefore, it is possible to cover the lower fixing portions 40A and 40B by using the lowermost riser plate 22X, and it is possible to further improve the accommodation around the lower portion of the steel staircase 10.

The lower fixing portion 40 includes a first lower fixing portion 40A and a second lower fixing portion 40B. Therefore, the first lower fixing portion 40A can be used to fix the first girder portion 30A to the floor 50, and the second lower fixing portion 40B can be used to fix the second girder portion 30B to the floor 50. In addition, since the lower fixing portions 40A and 40B are formed of flat plates, the anchor bolts 52 are inserted into the through holes 42 formed in the lower fixing portions 40A and 40B and nut tightening is performed to lower the lower portions of the anchor bolts 52. It is easy to fix the fixing portions 40A and 40B.

B. Modification:
The technology disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof, for example, the following modifications are also possible.

In the above embodiment, a steel frame building is exemplified as the structure, but the structure may be a reinforced concrete building or a structure other than the building. Moreover, although the steel frame staircase attached between the first floor and the second floor of the building is illustrated as the steel frame staircase, the steel frame staircase may be attached between the second floor and the third floor of the building. It may be attached to higher floors.

In the above-described embodiment, as a method of fixing the steel frame stairs to the upper frame, an example in which the girder upper portions 32 of the pair of girder portions 30 and the mounting plate 62 attached to the beam 60 are fixed by the bolts 66 has been shown. However, the girder upper portion 32 and the mounting plate 62 may be fixed by welding. Further, although the steel frame staircase in which the girder upper part 32 which is the upper end of the steel frame staircase does not reach the beam 60 is illustrated, the girder upper part 32 extends to the upper part of the beam 60 and is fixed to the mounting plate 62 at the upper part of the beam 60. It may have been done.

In the above-described embodiment, the lower fixing portions 40A and 40B are formed of flat plates, but the present invention is not limited to this, and the lower fixing portions 40A and 40B may be formed of L-shaped plates having a L-shaped cross section orthogonal to the front-rear direction. In this case, in the lower fixing portions 40A and 40B, the through hole 42 may be formed in one flat plate of the L-shaped plate, and the other flat plate may be joined to the inner surface of the corresponding girder portion 30 by welding.

In the above-described embodiment, the lower fixing portions 40A and 40B are arranged below the lowermost step plate 21X, but the present invention is not limited to this, and they may be arranged below the step plates 21 other than the lowermost step plate 21X. In this case, the lower fixing portions 40A and 40B may be arranged at the same height as or above the lowermost tread 21X, and the treads provided with the openings 24A and 24B based on the arrangement of the lower fixing portions 40A and 40B. 21 may also be changed appropriately. Further, for example, the lower fixing portions 40A and 40B are provided below the relatively upper tread plate 21 of the plurality of tread plates 21, and the worker can easily perform the work without the openings 24A and 24B. In this case, it is not always necessary to provide the openings 24A and 24B.

Although the openings 24A and 24B are arranged below the lower fixing portions 40A and 40B in the above-described embodiment, they are not necessarily arranged below the lower fixing portions 40A and 40B. That is, the openings 24A and 24B are not necessarily fixed to the lower side as long as they are provided in a range in which the operator can extend the arm from above the tread 21 through the openings 24A and 24B and perform the fixing work such as nut tightening. It need not be located above the parts 40A, 40B.

In the above embodiment, the step plate portion 20 includes the plurality of riser plates 22, but the present invention is not limited to this, and the step plate portion 20 may not include the riser plates 22.

In the above-described embodiment, the lower fixing portion 40 is configured by the two lower fixing portions 40A and 40B fixed to the pair of girder portions 30, respectively, but the present invention is not limited to this. For example, the lower fixing portion 40 may be configured by a series of steel plates supported between the pair of girder portions 30.

1: Building 10: Steel stairs 20: Step 21: Tread 21X: Bottom tread 22: Raised plate 22X: Bottom tread 24: Opening 28: Lid 30: Girder 32: Girder upper 38: Girder Lower part 40: Lower fixing part 42: Through hole 50: Floor 52: Anchor bolt 60: Beam 62: Mounting plate FL: Floor surface

Claims (5)

A steel frame staircase that is attached between the structure on the upper floor of the structure and the structure on the lower floor,
A pair of girder parts,
A plurality of treads joined and supported by welding between the pair of girder portions,
An upper fixing portion that fixes the pair of girder portions to the upper body,
A lower fixing part that fixes the pair of girders to the lower floor frame, is located between the pair of girders, and has a through hole into which an anchor bolt protruding from the floor of the lower floor is inserted. The formed lower fixing part,
A plurality of riser plates joined and supported by welding between the pair of girder portions ,
The lower fixing portion is below the lowermost tread arranged at the lowermost of the plurality of treads, and from the lowermost riser arranged between the lowermost tread and the floor of the lower floor. Is also placed on the rising side of the steel stairs,
The lower fixing portion has a flat portion arranged substantially parallel to the tread,
A part of the plane part is a steel staircase, which is arranged on the ascending side of the steel frame stairs with respect to the lowermost tread . The steel staircase according to claim 1 ,
The tread plate located above the lower fixing portion is provided with an opening penetrating in the vertical direction,
The steel staircase further comprises:
A steel frame staircase having a lid portion that opens and closes the opening. The steel staircase according to claim 1 or 2 ,
The lower fixing portion,
A first lower portion having a first flat surface portion fixed to a surface of one of the pair of girder portions on the other girder portion side, arranged substantially parallel to the tread plate, and having the through hole formed therein. Fixed part,
A second flat portion fixed to the surface of the other girder portion of the pair of girder portions on the side of the one girder portion, disposed substantially parallel to the tread plate, and having the through hole formed therein; Steel stairs including 2 lower fixing parts. The steel staircase according to any one of claims 1 to 3 ,
A steel frame staircase in which the lower end surfaces of the pair of girder portions are in contact with the surface of the lower body. Between the skeleton of the upper floor of the structure and the skeleton of the lower floor, a pair of girder parts, a plurality of treads joined and supported by welding between the pair of girder parts, and the pair of girder parts. An upper fixing part for fixing the upper floor frame and a lower fixing part for fixing the pair of girder parts to the lower floor frame, which is located between the pair of girder parts and has a through hole formed therein. A method of mounting a steel frame staircase, the method comprising:
Anchor bolts protruding from the floor surface of the lower floor are inserted into the through holes formed in the lower fixing portion so that the steel frame stairs are installed with respect to the body of the lower floor,
Have a, a fixing step of fixing the lower fixing part on the anchor bolt,
The steel frame staircase includes a plurality of riser plates joined and supported by welding between the pair of girder portions,
The lower fixing portion is below the lowermost tread arranged at the lowermost of the plurality of treads, and is the lowermost kicking plate arranged between the lowermost tread and the floor of the lower floor. Is also placed on the rising side of the steel stairs,
The lower fixing portion has a flat portion arranged substantially parallel to the tread,
A method for mounting a steel frame staircase , wherein a part of the plane portion is arranged on a rising side of the steel frame staircase with respect to the lowermost step plate .

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