Dog-legged staircase

Abstract

To suppress restrictions that an outdoor dog-legged staircase has on an installation place of an opening part.SOLUTION: A dog-legged staircase (20) is installed contiguously outside a building (1). The dog-legged staircase (20) has a rectangular outline consisting of a first short side (91), a second short side (92), and a pair of long sides (93 and 94) viewed from above. The first short side (91) is provided along an outer wall (16) of the building (1). The second short side (92) is apart from the outer wall (16). The long sides (93 and 94) are perpendicular to the outer wall (16).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a folding staircase.

Background Art

[0002] Patent Document 1 discloses an outdoor folding staircase adjacent to the outer wall of an apartment house. This folding staircase is a steel frame staircase. The side girders of the folding staircase are provided along the outer wall of the apartment house, and the ascending and descending directions of the folding staircase are along the direction of the outer wall of the apartment house.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, legally, an outdoor staircase needs to be installed at a predetermined distance from openings other than the entrance and exit leading to the outdoor staircase. Therefore, the outdoor staircase restricts the installation locations of openings other than the entrance and exit. Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to suppress the restriction imposed by an outdoor folding staircase on the installation location of an opening.

Means for Solving the Problems

[0005] The reference numerals shown in the following parentheses are referred to in FIGS. 1 to 9.

[0006] According to the invention according to claim 1, there is provided a folding staircase (20) installed adjacent to the outside of a building (1), which has a rectangular contour composed of a first short side (91), a second short side (92), and a pair of long sides (93 and 94) when viewed from above, wherein the first short side (91) is along the outer wall (16) of the building (1), the second short side (92) is away from the outer wall (16), and the long sides (93 and 94) are perpendicular to the outer wall (16).

[0007] According to the invention according to claim 1 as described above, since the folding staircase (20) has a rectangular contour, the first short side (91) of the rectangular contour is provided along the outer wall (16) of the building (1), and the long sides (93 and 94) of the rectangular contour are perpendicular to the outer wall (16) of the building (1), the area occupied by the folding staircase (20) with respect to the outer wall (16) of the building (1) can be minimized. Therefore, the constraints imposed by the folding staircase (20) on the installation location of the opening of the outer wall (16) can be suppressed.

[0008] According to the invention according to claim 2, there is provided a folding staircase (20) as described in claim 1, wherein the upward and downward directions of the staircase are along the long sides (93 and 94).

[0009] According to the invention according to claim 2 as described above, the constraints imposed by the folding staircase (20) on the installation location of the opening of the outer wall (16) can be suppressed.

[0010] According to the invention according to claim 3, there is provided a folding staircase (20) as described in claim 1 or 2, which is a steel-frame staircase.

[0011] According to the invention according to claim 4, there is provided a folding staircase (20) according to claim 3, comprising: a ramen structure (40) erected parallel to the outer wall (16) of the building (1) along the second short side (92); a plurality of pairs of support beams (21 and 22) extending from the beams (6) of each floor of the building (1) towards the ramen structure (40) along the long sides (93 and 94); a plurality of horizontal members (24) respectively installed between the ends of the plurality of pairs of support beams (21 and 22); a dance floor (30) respectively provided on the plurality of pairs of support beams (21 and 22) and the plurality of horizontal members (24); a plurality of pairs of lower girders (50) obliquely extending downward from the ends of the plurality of pairs of support beams (21 and 22) or from each of the plurality of horizontal members (24) to the ramen structure (40), parallel to the long sides (93 and 94) and parallel to each other; a plurality of pairs of upper girders (60) obliquely extending upward from the ends of the plurality of pairs of support beams (21 and 22) or from each of the plurality of horizontal members (24) to the ramen structure (40), parallel to the long sides (93 and 94) and parallel to each other; and an intermediate dance floor (70) provided at a portion closer to the ramen structure (40) among the lower girders (50) and the upper girders (60).

[0012] According to the invention according to claim 4 as described above, since the lower girders (50) are obliquely extended downward from the ends of the support beams (21 and 22) or the horizontal members (24) to the ramen structure (40), and the upper girders (60) are obliquely extended upward from the ends of the support beams (21 and 22) or the horizontal members (24) to the ramen structure (40), when seismic forces in the long side direction occur in the folding staircase (20), the seismic forces are borne by the beams (6) of the building (1) through the lower girders (50), the upper girders (60) and the support beams (21 and 22). Therefore, even if there is no beam extending along the long side direction installed between the ramen structure (40) and the beams (6) of the building (1), the folding staircase (20) can withstand the seismic forces in the long side direction. Further, when seismic forces in the short side direction occur in the folding staircase (20), the seismic forces are shared by the building (1) and the ramen structure (40). The folding staircase (20) can withstand the seismic forces in the short side direction.

[0013] According to the invention according to claim 5, there is provided a folding staircase (20) according to claim 4, characterized in that it comprises a plurality of braces (27) respectively installed between the plurality of pairs of support beams (21 and 22).

[0014] According to the invention according to claim 5 as described above, the braces (27) reinforce the support beams (21 and 22) so that the support beams (21 and 22) can withstand the bending moment caused by the horizontal load. Therefore, the braces (27) contribute to narrowing the width of the support beams (21 and 22).

[0015] According to the invention according to claim 6, there is provided a folding staircase (20) according to claim 4, characterized in that one end of the upper girder (60) and the lower girder (50) is fixed to the ramen structure (40), and the other ends of the upper girder (60) and the lower girder (50) are fixed to the support beams (21 and 22) or the horizontal members (24).

[0016] According to the invention according to claim 6 as described above, by fixing both ends of the upper girder (60) and the lower girder (50) to the ramen structure (40) and the support beams (21 or 22) or the horizontal members (24) respectively, the horizontal force can be transmitted. Therefore, it is not necessary to install braces between these upper girder (60) and lower girder (50).

[0017] According to the invention according to claim 7, there is provided a folding staircase according to claim 4, characterized in that the installation height of the beam (6) of the building (1) is the structural floor height of each floor of the building (1).

Effect of the Invention

[0018] According to the present invention, the restrictions imposed by the folding staircase on the installation location of the outer wall opening can be suppressed.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments will be described with reference to the drawings. The features and technical effects of the embodiments will be understood from the following detailed description and the drawings. However, the scope of the present invention is not limited to the embodiments disclosed below. Since the drawings are provided for illustrative purposes only, the scope of the present invention is not limited to the illustrations in the drawings.

[0021] Figure 1 is an east elevation view of the building, and Figure 2 is a west elevation view of the building. Note that the orientation of the building can be changed according to the location. The building has a building 1 and a return staircase 20.

[0022] 〔1. Building〕 Building 1 is a steel-frame building, more specifically, a building with a steel-frame ramen structure. Building 1 has six floors. The number of floors of Building 1 is not limited to six as long as it is two floors or more. Building 1 is provided with a foundation, a ramen framework, an outer wall, and slabs for each floor. The foundation is fixed to the ground. The ramen framework is framed on the foundation. The outer wall is attached to the outer periphery of the ramen framework. The outer wall separates the inside and the outside of Building 1. The slab on the first floor is laid on the foundation, and the slabs on the second floor and above are laid on the beams of the ramen framework.

[0023] Figure 3 is a south elevation view showing the framing of the ramen framework of Building 1. Figure 4 is a plan view showing the ramen framework of the southwestern part of the second floor of Building 1. The ramen framework of Building 1 has columns 2 to 5, a plurality of large beams 6, a plurality of large beams 7, a plurality of large beams 8, a plurality of large beams 9, a plurality of small beams 10, and a plurality of small beams 11. The ramen framework has columns and beams other than columns 2 to 5, large beams 6 to 9, and small beams 10 and 11, but since those columns and beams are away from the return staircase 20, the illustration of those columns and beams is omitted.

[0024] Columns 2 to 5 are vertically erected on the foundation. Column 2 is arranged at the southwestern corner of Building 1. Column 3 is arranged eastward from Column 2, separated along the southern outer wall 16 forming the southwestern corner of Building 1. Column 4 is arranged northward from Column 2, separated along the western outer wall 17 forming the southwestern corner of Building 1. Column 5 is arranged eastward from Column 4 and northward from Column 3, separated from these Columns 3 and 4. Column 5 is arranged at the diagonal position of Column 2. Columns 2 to 5 are square steel tube columns. The main beam 6 is horizontally installed between Column 2 and Column 3 at the structural floor height of each floor. The main beam 7 is horizontally installed between Column 2 and Column 4 at the structural floor height of each floor. The main beam 8 is horizontally installed between Column 4 and Column 5 at the structural floor height of each floor. The main beam 9 is horizontally installed between Column 3 and Column 5 at the height of the structural floor height of each floor. The main beams 6 to 9 are H-shaped steel beams. The secondary beams 10 and 11 are horizontally installed between the main beam 6 and the main beam 8 at the height of the structural floor height of each floor and are provided parallel to the main beams 7 and 9. The secondary beams 10 and 11 are H-shaped steel beams. The outer wall 16 is attached to Columns 2, 3 and the main beam 6, and the outer wall 17 is attached to Columns 2, 4 and the main beam 7. The outer wall 16 forms the southern side of Building 1, and the outer wall 17 forms the western side of Building 1.

[0025] 〔2. Return Staircase〕 As shown in FIGS. 1 and 2, the return staircase 20 is a steel staircase. The return staircase 20 is installed outside Building 1, particularly adjacent to the south of Building 1. The return staircase 20 is used as an evacuation staircase. The return staircase 20 leads to each floor from the first floor to the fifth floor of Building 1. As shown in FIG. 4, the return staircase 20 has a rectangular outline composed of a first short side 91, a second short side 92 and a pair of long sides 93, 94 when viewed from above. The first short side 91 is along the outer wall 16 of Building 1, the second short side 92 is separated from the outer wall 16 of Building 1 to the south outdoors, and the pair of long sides 93, 94 are perpendicular to the outer wall 16. The up and down directions in the return staircase 20 are along the long sides 93, 94 of the rectangular outline.

[0026] Figs. 5 and 6 are perspective views showing the skeletons of the folded staircase 20 from the first floor to the third floor. Fig. 7 is a south elevation view showing the ramen structure 40 of the folded staircase 20. Figs. 8 and 9 are sectional views showing the section along line VIII-VIII shown in Fig. 4 as viewed in the direction of the arrow. Fig. 8 mainly shows the part of the folded staircase 20 from the first floor to the third floor, and Fig. 9 mainly shows the part of the folded staircase 20 from the third floor to the fifth floor.

[0027] As shown in Figs. 4 to 9, the folded staircase 20 includes a plurality of pairs of support beams 21, 22, a plurality of pairs of horizontal members 23, 24, a plurality of braces 27, a plurality of landings 30, a ramen structure 40, a plurality of pairs of lower girders 50, a plurality of sets of treads 55, a plurality of sets of kick plates 56, a plurality of pairs of upper girders 60, a plurality of sets of treads 65, a plurality of sets of kick plates 66, a plurality of intermediate landings 70, and the uppermost auxiliary girder 69 (see Fig. 1).

[0028] [2-1. Landings on Each Floor from the Second Floor to the Fifth Floor] The support beams 21, 22, the horizontal members 23, 24, and the braces 27 are located at a position slightly lower than the floor level of each floor above the second floor. The support beam 21 is fixed to the joints of the column 2 and the large beam 6 at the structural floor height of each floor from the first floor to the fourth floor. The support beam 21 extends horizontally southward along the long side 93 from the joints of the column 2 and the large beam 6 and penetrates the outer wall 16 on the south side. The support beam 21 is arranged at a position where the large beam 7 is extended southward. The support beam 22 is fixed to the large beam 6 at the structural floor height of each floor from the first floor to the fourth floor. The support beam 22 extends horizontally southward along the long side 94 from the large beam 6 and penetrates the outer wall 16 on the south side. The support beam 22 is arranged at a position where the small beam 10 is extended southward.

[0029] The support beams 21, 22 are provided parallel to each other. The support beams 21, 22 are H-shaped steels having a weak axis and a strong axis perpendicular to the direction in which they extend. The strong axis of the support beams 21, 22 is horizontal, and the weak axis of the support beams 21, 22 is vertical. The bending rigidity of the support beams 21, 22 around the strong axis is higher than the bending rigidity of the support axes 21, 22 around the weak axis.

[0030] The horizontal member 23 is horizontally installed between the support beams 21 and 22 at the structural floor height of each floor from the first floor to the fourth floor. The horizontal member 23 is arranged at a position close to the outer wall 16 on the outer side of the outer wall 16. The horizontal member 24 is horizontally installed between the tips of the support beams 21 and 22 at the structural floor height of each floor from the first floor to the fourth floor. The horizontal members 23 and 24 are provided parallel to each other. The horizontal members 23 and 24 are H-shaped steel. The brace 27 is installed between the diagonals of the rectangular frame formed by the support beams 21, 22 and the horizontal members 23, 24 at the structural floor height of each floor from the first floor to the fourth floor. The brace 27 reinforces the support beams 21 and 22 so that the support beams 21 and 22 can withstand the bending moment around the weak axis due to the horizontal load. Therefore, the brace 27 contributes to narrowing the width of the support beams 21 and 22. Where the support beams 21 and 22 are passed through the through holes formed in the outer wall 16, the brace 27 contributes to narrowing the width of those through holes.

[0031] The dance floor 30 is fixed on the support beams 21, 22 and the horizontal members 23, 24 at the floor level of each floor from the second floor to the fifth floor. The dance floors 30 of each floor from the second floor to the fifth floor have a flat upper surface aligned with the floor level of each floor from the second floor to the fifth floor. The dance floor 30 has a raised platform 31 and a floor board 32. The raised platform 31 is framed by a section steel such as channel steel. The raised platform 31 is fixed on the support beams 21, 22 and the horizontal members 23, 24. The floor board 32 is laid on the raised platform 31. The upper surfaces of the floor boards 32 of each floor from the second floor to the fifth floor are aligned with the floor level of each floor. Note that, as shown in FIGS. 1, 2 and 3, the dance floor 39 on the first floor is made of a concrete structure.

[0032] Fences are erected on the east and west edges of the dance floor 30. In the above description, the installation height of the beam 6 to which the support beams 21 and 22 are fixed is the structural floor height of each floor of the building 1. In contrast, the beam 6 may be installed with a deviation upward or downward from the structural floor height.

[0033] 〔2-2. Ramen Structure〕 As shown in FIGS. 4 to 9, the ramen structure 40 is erected on the foundation at a position away from the vertical plane formed by the columns 2 and 3 and the large beam 6 and the outer wall 16 to the south outdoors. The ramen structure 40 is erected along the second short side 92 parallel to the vertical plane formed by the columns 2 and 3 and the large beam 6 and the outer wall 16.

[0034] The ramen structure 40 has columns 41 and 42 and a plurality of beams 43. The columns 41 and 42 are square steel pipe columns, and the beams 43 are H-shaped steels. The column 41 is vertically erected on the foundation on the opposite side of the column 4 with respect to the corner column 2 of the building 1. The column 41 is located south of the column 2 and is arranged at a position where the outer wall 17 is extended southward. The column 42 is vertically erected on the foundation at a position away from the column 41 to the east. The column 42 is arranged at a position where the small beam 10 is extended southward. The vertical plane formed by the column 41 and the column 42 is parallel to the vertical plane formed by the columns 2 and 3 and the large beam 6 and the outer wall 16. The beam 43 is horizontally installed between the column 41 and the column 42 in the middle of the floor height of each floor. The beam 43 supports the middle dance floor 70 from below the middle dance floor 70.

[0035] In the following description, the dance floor 30 on the floor half a floor above the beam 43 and the middle dance floor 70 is referred to as the upper floor dance floor 30, and the dance floor 30 or 39 on the floor half a floor below the beam 43 and the middle dance floor 70 is referred to as the lower floor dance floor 30 or 39. The support beams 21 and 22 and the horizontal members 23 and 24 that support the upper floor dance floor 30 are referred to as the upper floor support beams 21 and 22 and the upper floor horizontal members 23 and 24, and the support beams 21 and 22 and the horizontal members 23 and 24 that support the lower floor dance floor 30 are referred to as the lower floor support beams 21 and 22 and the lower floor horizontal members 23 and 24.

[0036] [2-3. Between the 2nd and 3rd floors] Between the second and third floors, a pair of lower girders 50 are arranged parallel to each other and separated east-west within the eastern half region inside the rectangular contour formed by the short sides 91, 92 and the long sides 93, 94. A pair of upper girders 60 are arranged parallel to each other and separated east-west within the western half region inside the rectangular contour. The pair of lower girders 50 are parallel to the long sides 93, 94 of the rectangular contour, and the eastern lower girder 50 of the pair of lower girders 50 is along the long side 94 of the rectangular contour. The pair of upper girders 60 are parallel to the long sides 93, 94 of the rectangular contour, and the western upper girder 60 of the pair of upper girders 60 is along the long side 93 of the rectangular contour.

[0037] Of the pair of lower girders 50, the eastern lower girder 50 is obliquely spanned from the tip of the lower floor support beam 22 southward to the joint of the beam 43 and the column 42 with respect to the horizontal plane. The north end of the lower girder 50 is fixed to the tip of the lower floor support beam 22, and the south end of the lower girder 50 is fixed to the joint of the beam 43 and the column 42. The western lower girder 50 is obliquely spanned from the lower floor horizontal member 24 southward to the beam 43 with respect to the horizontal plane. The north end of the lower girder 50 is fixed to the lower floor horizontal member 24, and the south end of the lower girder 50 is fixed to the beam 43.

[0038] These lower girders 50 have an inclined portion 51 that extends obliquely upward southward from the lower floor horizontal member 24 to the intermediate landing 70, and a horizontal portion 52 that extends horizontally southward from the south end of the inclined portion 51 to the beam 43. The north end of the inclined portion 51 of the eastern lower girder 50 is fixed to the tip of the lower floor support beam 22. The north end of the inclined portion 51 of the eastern lower girder 50 may be fixed to the lower floor horizontal member 24. The south end of the horizontal portion 52 of the eastern lower girder 50 is fixed to the joint of the beam 43 and the column 42. The north end of the inclined portion 51 of the western lower girder 50 is fixed to the lower floor horizontal member 24. The south end of the horizontal portion 52 of the western lower girder 50 is fixed to the beam 43.

[0039] A plurality of tread plates 55 and a plurality of kick plates 56 are arranged between and fixed to the inclined portions 51 of these lower girders 50. Note that the kick plates 56 may not be provided. A fence is erected on the upper edge of these lower girders 50.

[0040] Of the pair of upper girders 60, the western upper girder 60 is obliquely spanned from the joint of the beam 43 and the column 41 northward to the tip of the upper floor support beam 21 with respect to the horizontal plane. The northern end of the upper girder 60 is fixed to the tip of the upper floor support beam 21, and the southern end of the upper girder 60 is fixed to the joint of the beam 43 and the column 41. The eastern upper girder 60 is obliquely spanned from the beam 43 northward to the upper floor horizontal member 24 with respect to the horizontal plane. The northern end of the upper girder 60 is fixed to the upper floor horizontal member 24, and the southern end of the upper girder 60 is fixed to the beam 43.

[0041] These upper girders 60 have an inclined portion 61 that extends obliquely downward southward from the upper floor horizontal member 24 to the intermediate dance floor 70, and a horizontal portion 62 that extends horizontally southward from the southern end of the inclined portion 61 to the beam 43. The northern end of the inclined portion 61 of the western upper girder 60 is fixed to the tip of the upper floor support beam 21. The southern end of the horizontal portion 62 of the western upper girder 60 is fixed to the joint of the beam 43 and the column 41. The northern end of the inclined portion 61 of the eastern upper girder 60 is fixed to the upper floor horizontal member 24. The southern end of the horizontal portion 62 of the eastern upper girder 60 is fixed to the beam 43.

[0042] A plurality of tread plates 65 and a plurality of kick plates 66 are arranged between the inclined portions 61 of these upper girders 60 and are fixed to the inclined portions 61 of these upper girders 60. Note that the kick plate 66 may not be provided. A fence is erected on the upper edges of these upper girders 60.

[0043] The intermediate dance floor 70 is horizontally arranged between the horizontal portion 52 of the lower girder 50 on the east side and the horizontal portion 62 of the upper girder 60 on the west side, and is fixed to the horizontal portion 52 of the lower girder 50 on the east side and the horizontal portion 62 of the upper girder 60 on the west side. The intermediate dance floor 70 is also laid on the horizontal portion 52 of the lower girder 50 on the west side, the horizontal portion 62 of the upper girder 60 on the east side, and the beam 43, and is supported by these.

[0044] Fences are erected on the west, east, and south edges of the intermediate dance floor 70.

[0045] Similar to the space between the 2nd and 3rd floors, a pair of lower girders 50, a plurality of tread plates 55, a plurality of kick plates 56, a pair of upper girders 60, a plurality of tread plates 65, a plurality of kick plates 66, an intermediate dance floor 70 and fences are installed between the 3rd and 4th floors.

[0046] Similar to the space between the 2nd and 3rd floors, a pair of lower girders 50, a plurality of tread plates 55, a plurality of kick plates 56, a pair of upper girders 60, a plurality of tread plates 65, a plurality of kick plates 66, an intermediate dance floor 70 and fences are installed between the 4th and 5th floors. As shown in Fig. 1, in addition to these, an auxiliary girder 69 is installed between the 4th and 5th floors. The auxiliary girder 69 is arranged away from the upper girder 60 on the east side to the east. The auxiliary girder 69 is obliquely spanned from the horizontal part 52 of the lower girder 50 on the east side northward to the tip of the upper floor support beam 22 with respect to the horizontal plane. The north end of the auxiliary girder 69 is fixed to the tip of the upper floor support beam 22, and the south end of the auxiliary girder 69 is fixed to the horizontal part 52 of the lower girder 50 on the east side.

[0047] Similar to the space between the 2nd and 3rd floors, a pair of upper girders 60, a plurality of tread plates 65, a plurality of kick plates 66, an intermediate dance floor 70 and fences are installed between the 1st and 2nd floors.

[0048] ​​Between the first floor and the second floor, a pair of lower girders 50 are arranged parallel to each other with a space therebetween in the eastern half region inside the rectangular contour formed by the short sides 91, 92 and the long sides 93, 94. The eastern lower girder 50 of the pair of lower girders 50 is along the long side 94 of the rectangular contour. The eastern lower girder 50 of the pair of lower girders 50 is obliquely spanned from the lower floor dance floor 39 southward to the joint of the beam 43 and the column 42 with respect to the horizontal plane, the northern end of the lower girder 50 is fixed to the lower floor dance floor 39, and the southern end of the lower girder 50 is fixed to the joint of the beam 43 and the column 42. The western lower girder 50 is obliquely spanned from the lower floor dance floor 39 southward to the beam 43 with respect to the horizontal plane, the northern end of the lower girder 50 is fixed to the lower floor dance floor 39, and the southern end of the lower girder 50 is fixed to the beam 43. These lower girders 50 have an inclined portion 51 extending obliquely upward southward from the lower floor dance floor 39 to the intermediate dance floor 70, and a horizontal portion 52 extending horizontally southward from the southern end of the inclined portion 51 to the beam 43. The northern end of the inclined portion 51 of these lower girders 50 is fixed to the lower floor dance floor 39. The southern end of the horizontal portion 52 of the eastern lower girder 50 is fixed to the joint of the beam 43 and the column 41. The southern end of the horizontal portion 52 of the western lower girder 50 is fixed to the beam 43. A plurality of treads 55 and a plurality of kick plates 56 are arranged between and fixed to the inclined portions 51 of these lower girders 50. Note that the kick plates 56 may not be provided. A fence is erected on the upper edge of these lower girders 50.

[0049] [3. Advantageous Technical Effects] (1) As shown in FIG. 4, when viewed from above, the return staircase 20 has a rectangular contour formed by the short sides 91, 92 and the long sides 93, 94. The first short side 91 of the rectangular contour is provided along the outer wall 16 of the building 1, and the long side 93 of the rectangular contour is perpendicular to the outer wall 16 of the building 1. Therefore, when viewed from the south, the area occupied by the return staircase 20 with respect to the outer wall 16 of the building 1 is minimized, and the restriction imposed by the return staircase 20 on the installation location of the opening of the outer wall 16 is suppressed. This contributes to an improvement in the degree of freedom of the installation location of the opening. Here, the opening refers to, for example, an openable window.

[0050] (2) The lower girder 50 on the east side is obliquely spanned horizontally from the tip of the lower floor support beam 22 southward to the joint of the beam 43 and the column 42, and the lower girder 50 on the west side is obliquely spanned horizontally from the lower floor horizontal member 24 southward to the beam 43. The upper girder 60 on the west side is obliquely spanned horizontally from the joint of the beam 43 and the column 41 northward to the tip of the upper floor support beam 21, and the upper girder 60 on the east side is obliquely spanned horizontally from the beam 43 northward to the upper floor horizontal member 24. Therefore, when seismic forces in the long side direction occur in the folded staircase 20, the seismic forces are borne by the ramen structure of the building 1 through a plurality of lower girders 50, a plurality of upper girders 60, a plurality of support beams 21 and a plurality of support beams 22. Thus, even if there are no beams extending along the long side direction installed between the ramen structure 40 and the main beam 6 of the building 1, the folded staircase 20 can withstand seismic forces.

[0051] (3) The horizontal seismic forces are distributed to the ramen structure 40 and the ramen structure of the building 1 according to the direction of the sides of the folded staircase. That is, the seismic forces in the long side direction are borne by the ramen structure of the building 1, and the seismic forces in the short side direction are shared by the ramen structure of the building 1 and the ramen structure 40. Therefore, the folded staircase 20 can withstand seismic forces in both the short side direction and the long side direction.

[0052] (4) The southern end of the lower girder 50 on the east side is fixed to the joint of the ramen structure 40, and the southern end of the lower girder 50 on the west side is fixed to the beam 43 of the ramen structure 40. The southern end of the upper girder 60 on the west side is fixed to the joint of the ramen structure 40, and the southern end of the upper girder 60 on the east side is fixed to the beam 43 of the ramen structure 40. Therefore, even if braces are not installed between a pair of lower girders 50 and between a pair of upper girders 60 respectively, the horizontal seismic forces generated in the folded staircase 20 can be transmitted.

[0053] (5) The brace 27 is installed between the support beams 21 and 22. The brace 27 reinforces the support beams 21 and 22 so that they can withstand the bending moment about the weak axis due to the horizontal load. Therefore, the brace 27 contributes to narrowing the width of the support beams 21 and 22. Where the support beams 21 and 22 are passed through the through holes formed in the outer wall 16, the brace 27 contributes to narrowing the width of these through holes.

[0054] (6) The building 1 and the return staircase 20 are made of steel frames, which have high seismic resistance and a long lifespan. Therefore, the building 1 and the return staircase 20 contribute to the achievement of goals such as so-called "building construction for continuous living" and "SDGs (Sustainable Development Goals)".

Description of Reference Numerals

[0055] 1 Building 6 Girder 16 Outer Wall 20 Return Staircase 21,22 Support Beam 23,24 Horizontal Member 30 Dance Floor 40 Ramen Structure 50 Lower Girder 60 Upper Girder 70 Intermediate Dance Floor 91 First Short Side 92 Second Short Side 93,94 Long Side

Claims

1. A folding staircase installed adjacent to the outside of a building, which has a rectangular outline composed of a first short side, a second short side, and a pair of long sides when viewed from above, wherein the first short side is along the outer wall of the building, the second short side is away from the outer wall, and the long sides are perpendicular to the outer wall. A folding staircase characterized by the above.

2. The folding staircase according to Claim 1, wherein the ascending and descending directions of the staircase are along the long sides. A folding staircase characterized by the above.

3. The folding staircase according to Claim 1 or 2, which is a steel-frame staircase. A folding staircase characterized by the above.

4. The folding staircase according to Claim 3, a ramen structure erected parallel to the outer wall of the building along the second short side, a plurality of pairs of support beams extending from the beam of the building towards the ramen structure along the long side, a plurality of horizontal members respectively installed between the tips of the plurality of pairs of support beams, a dance floor respectively provided on the plurality of pairs of support beams and the plurality of horizontal members, a plurality of pairs of lower girders obliquely spanned downward from the tips of the plurality of pairs of support beams or from each of the plurality of horizontal members to the ramen structure, parallel to the long side and parallel to each other, a plurality of pairs of upper girders obliquely spanned upward from the tips of the plurality of pairs of support beams or from each of the plurality of horizontal members to the ramen structure, parallel to the long side and parallel to each other, an intermediate dance floor provided at a portion closer to the ramen structure among the lower girders and the upper girders, A folding staircase characterized by comprising the above.

5. The folding staircase according to Claim 4, which comprises a plurality of braces respectively installed between the plurality of pairs of support beams. A folding staircase characterized by the above.

6. The folding staircase according to Claim 4, wherein one end of the upper girders and the lower girders is fixed to the ramen structure, and one end of the upper girders and the lower girders is respectively fixed to the support beams or the horizontal members. A folding staircase characterized by the above.

7. The folding staircase according to Claim 4, wherein the installation height of the beam of the building is the structural floor height of each floor of the building. A folding staircase characterized by the above.

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