Roof structure

Abstract

To provide a roof structure capable of achieving a safe structure against external force without the need for introduction of initial tension excessively.SOLUTION: A roof structure is configured such that initial tension is introduced to a main cable 51 to apply the tension to a first ring part 53, the main cable 51, the first ring part 53, an upper chord material 52, a second ring part 54, and connection members (a first bundle material 61, a second bundle material 62, a diagonal material 63, sub-cables 65, 66, and a three-dimensional cable 56) are supported by a lower structure 3 with a stable self-balancing structure being constructed, and when external force acting on a chord tensioning truss part 5 is a predetermined value or higher and the tension of the main cable 51 and the first ring part 53 disappears, the upper chord material 52, the second ring part 54, the connection members, and an additional structural member 8 resist external force.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a roof structure.

Background Art

[0002] The roofs of large spaces such as stadiums have a large span. If not having a reasonable structure, they will become extremely heavy roofs, which is not economical. Especially in Japan where seismic forces are large, the heavy roof increases the external force on the lower structure, leading not only to concerns about safety but also to an increase in the construction cost of the entire building. Since many stadiums are required to reduce costs, shorten construction periods, and reduce environmental impacts by not using excessive materials, a reasonable structure is sometimes adopted.

[0003] Also, in soccer stadiums, it is often the case that no roof is provided on the ground part and only the spectator seats are provided with a roof. This is because according to the FIFA international standards for stadiums, the ground is required to be natural grass or a hybrid of artificial grass. Also, although it is not essential to provide a roof above the spectator seats, there is a tendency that it is customarily required. Therefore, there is a demand to ensure sunlight on the ground part while a roof is required above the spectator seats.

[0004] In such a roof structure, as an example of using a "tensile structure" that can make the roof lightweight, there is a wheel-type structure (spoked-wheel) system that is particularly widely realized overseas (see, for example, Patent Document 1). There are many wheel-type structure systems composed of cables and the like overseas. Especially when a membrane material is used in combination, due to its characteristics that combine the finishing material and the structure, there is also an advantage that it can realize a lightweight, bright, and open stadium space without visual heaviness. By not providing a roof within the central ring, sunlight can be ensured on the ground, so it is considered a structure system suitable for stadiums.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002-322830 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, in Japan where not only seismic forces but also wind pressure is large, if we try to directly use overseas wheel-shaped structure systems, in order to resist wind pressure (so that the tension is not lost by wind pressure), it is necessary to make the initial tension in the cable extremely large, which poses a very difficult problem to achieve. Also, regarding the shape, since the above-mentioned system is most stable in a planar perfect circular shape, the larger the tension becomes, it becomes even more difficult to stabilize in cases such as an ellipse conforming to the shape of a stadium or when there are height differences on the roof.

[0007] An object of the present invention is to provide a roof structure that does not require excessive introduction of initial tension and can realize a structure that is safe against external forces. [Means for Solving the Problems]

[0008] In order to achieve the above object, the roof structure according to the present invention includes an annular cable-truss part supported by a lower structure, an additional structural member connecting the cable-truss part and the lower structure, and a membrane part stretched over the cable-truss part. The cable-truss part includes a plurality of lower chords arranged radially, an annular first ring part arranged inside the plurality of lower chords in the radial direction and to which the plurality of lower chords are joined, a plurality of upper chords arranged radially above the plurality of lower chords, an annular second ring part arranged inside the plurality of upper chords in the radial direction and to which the plurality of upper chords are joined, and a connecting member connecting the lower chords and the upper chords. An initial tension is introduced into the lower chords to apply tension to the first ring part, and the lower chords, the first ring part, the upper chords, the second ring part, and the connecting member are supported by the lower structure in a state where a stable self-balancing structure is constructed. When an external force acting on the cable-truss part becomes equal to or greater than a predetermined value and the tension in the lower chords and the first ring part disappears, the upper chords, the second ring part, the connecting member, and the additional structural member are configured to resist the external force.

[0009] In the present invention, when an external force equal to or greater than a predetermined value acts and the tension in the lower chords and the first ring part disappears, the upper chords, the second ring part, the connecting member, and the additional structural member resist the external force. Therefore, the initial tension introduced into the lower chords does not have to be large enough to resist all external forces, and may be set to a magnitude that allows the cable-truss part to construct a stable self-balancing structure. As a result, there is no need to excessively introduce the initial tension into the lower chords. In addition, since the cable-truss part can resist external forces even when the tension in the lower chords and the first ring part disappears, a safe structure can be realized against disturbances such as during wind loads. Further, for example, when the cable - stayed truss part has an annular structure with a planar elliptical shape or an annular structure with a wavy shape having a height difference, it is an unstable structure compared to a perfect circle or a shape without a height difference. Therefore, a strong bending rigidity is required for the cable - stayed truss part. In particular, when the initial tension introduced into the lower chord member increases, it becomes necessary to further increase this bending rigidity. In the present invention, since the initial tension introduced into the lower chord member can be suppressed to a small value, the bending strength required can be suppressed even in the case of an annular structure in which the cable - stayed truss part has a planar elliptical shape or an annular structure with a wavy shape having a height difference. Furthermore, in the case of an annular structure with a planar elliptical shape or an annular structure with a wavy shape having a height difference, it is very difficult to stabilize it with respect to the initial tension. However, in the present invention, it can be easily stabilized by introducing tension into the lower chord member. The “annular” and “wheel - type” in the present invention shall include not only cases where the outer shape is a perfect circle but also cases of an ellipse or a polygon.

[0010] Also, in the roof structure according to the present invention, the additional structural member may be a pull - in cable that is joined to the cable - stayed truss part and joined to the lower structure body below the cable - stayed truss part.

[0011] By adopting such a configuration, when the uplifting wind pressure acts, the stress generated in the cable - stayed truss part by the pull - in cable can be reduced.

[0012] Also, in the roof structure according to the present invention, it has an outer - peripheral steel - frame part provided on the outer periphery of the cable - stayed truss part and supported by the lower structure body, and the cable - stayed truss part may be joined to the outer - peripheral steel - frame part and supported by the lower structure body via the outer - peripheral steel - frame part.

[0013] By adopting such a configuration, a solar panel or the like can be installed on the roof on the outer - peripheral steel - frame part, and functions can be added to the roof.

[0014] In addition, in the roof structure according to the present invention, the film portion may include a film material stretched over the cable - stayed truss portion and a pressing cable joined to the cable - stayed truss portion for pressing the film material.

[0015] With such a configuration, since the film material can be installed for each span and pressed by the pressing cable, the workability is good. Also, by introducing tension into the pressing cable, the film material can be maintained in a stretched state. When the tension of the film material is reduced due to aging deterioration, maintenance can be performed by introducing tension into the pressing cable.

Effects of the Invention

[0016] According to the present invention, it is not necessary to introduce excessive initial tension, and a structure safe against external forces can be realized.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

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Figure 12

Embodiment for Carrying out the Invention

[0018] Hereinafter, the roof structure 1 according to the embodiment of the present invention will be described with reference to FIGS. 1-12. As shown in FIGS. 1 and 2, the roof structure 1 according to the present embodiment is the structure of a roof 2 such as a stadium 11. The stadium 11 has spectator seats 13 provided around the ground 12. The spectator seats 13 are provided at a position higher than the ground 12. Various rooms are provided below the spectator seats 13. In the present embodiment, the planar shape of the stadium 11 is an ellipse. In the following description, the direction of rotation about the center of the ellipse of the stadium 11 will be denoted as the circumferential direction (the direction of arrow A in the figure), and the direction from the center of the ellipse toward the outer edge will be denoted as the radial direction (the direction of arrow B in the figure). The side that becomes the outer edge with respect to the center of the ellipse in the radial direction is the outside, and the side that becomes the center with respect to the outer edge is the inside.

[0019] As shown in FIGS. 1 and 3, the planar shape of the roof 2 is an annular shape (wheel type) along the outer periphery of the stadium 11, and the outer shape is an ellipse. As shown in FIGS. 1 and 2, the roof 2 covers the upper part of the spectator seats 13 and does not cover the upper part of the ground 12. The roof 2 has a wavy shape with height differences in the circumferential direction and the radial direction (see FIG. 1). The roof 2 is joined to the upper end of the lower structure 3 and is supported by the lower structure 3. The spectator seats 13 are provided on the lower structure 3.

[0020] The lower structure 3 is, for example, of a steel frame structure, and the planar shape is an annular shape surrounding the ground 12. Annular structural surfaces 31, 32 are provided on the lower structure 3. The spectator seats 13 are installed on the structural surfaces 31, 32. The lower structure 3 has improved rigidity and suppressed deformation due to the provision of the annular structural surfaces 31, 32. As shown in FIG. 2, in the present embodiment, the lower structure 3 is supported by pile foundations 33 embedded in the ground 14.

[0021] As shown in FIGS. 2 and 3, the roof structure 1 has an annular outer peripheral steel frame portion 4 provided on the outer peripheral side and joined to the lower structure 3, an annular cable truss portion 5 provided inside the outer peripheral steel frame portion 4, a membrane portion 7 stretched on the upper surface of the cable truss portion 5, and an additional structural member 8 connecting the cable truss portion 5 and the lower structure 3. The planar shapes of the outer peripheral steel frame portion 4, the cable truss portion 5, and the membrane portion 7 are all elliptical.

[0022] The outer peripheral steel frame portion 4 is composed of, for example, steel beams. The outer edge portion of the outer peripheral steel frame portion 4 is joined to the upper end portion 3a of the lower structure 3. In this embodiment, a solar panel (not shown) is installed on the upper part of the outer peripheral steel frame portion 4. The cable truss portion 5 is joined to the outer peripheral steel frame portion 4. The cable truss portion 5 is supported by the lower structure 3 via the outer peripheral steel frame portion 4.

[0023] As shown in FIG. 2, the cable truss portion 5 has a plurality of main cables 51 (lower chords) arranged radially, a plurality of upper chords 52 arranged radially above the main cables 51, an annular first ring portion 53 (tension ring) connected to the plurality of main cables 51, an annular second ring portion 54 joined to the plurality of upper chords 52, bundled members 61, 62 (connecting members), diagonal members 63 (connecting members), sub-cables 65, 66, and a three-dimensional cable 56.

[0024] The plurality of upper chords 52 are, for example, made of steel and have bending rigidity. The plurality of upper chords 52 are each long members. The upper chords 52 in this embodiment are linear members. The plurality of upper chords 52 are arranged radially over the entire circumferential direction of the cable truss portion 5. The plurality of upper chords 52 each extend in the radial direction when viewed from the vertical direction. As described above, the roof 2 has a wavy shape with height differences in the circumferential and radial directions. For this reason, the angles at which the plurality of upper chords 52 are arranged with respect to the horizontal plane are not all the same and are different. For example, as shown in FIG. 4, the upper chord 52 may extend horizontally, or as shown in FIG. 5, the upper chord 52 may extend such that the inner side is located above the outer side in the radial direction. Returning to FIG. 2, each of the plurality of upper chord members 52 has a first end portion 52a on the outer side in the radial direction joined to the outer peripheral steel frame portion 4.

[0025] The second ring portion 54 has bending rigidity. The second ring portion 54 is annular when viewed from the vertical direction. The second end portions 52b of the plurality of upper chord members 52 are fastened to the second ring portion 54 respectively. In the second ring portion 54 of the present embodiment, for example, annular members 541, 541 (compression rings) having the same cross-sectional shape such as steel frames are arranged in a double layer in the radial direction. An in-plane brace 542 is assembled between the two annular members 541, 541. By assembling the in-plane brace 542 between the two annular members 541, 541, the bending rigidity of the second ring portion 54 can be increased. An in-plane truss may be assembled between the two annular members 541, 541 instead of the in-plane brace 542. In the present embodiment, a spring-out portion 67 protruding inward in the radial direction is provided inside the second ring portion 54. For example, a eaves or the like can be provided on the spring-out portion 67.

[0026] The plurality of main cables 51 are cable materials capable of bearing tensile force. The plurality of main cables 51 are arranged radially over the entire circumferential direction of the cable-stayed truss portion 5. The plurality of main cables 51 each extend in the radial direction when viewed from the vertical direction. As shown in FIGS. 4 and 5, the angles at which the plurality of main cables 51 extend are not all the same but different. Also, the angle changes at the connection position with the second bundled member 62 described later. The plurality of main cables 51 are each arranged below the upper chord member 52 in the vertical direction. The first end portion 51a on the outer side in the radial direction of the main cable 51 is joined to the first end portion 52a of the upper chord member 52.

[0027] The first ring portion 53 can bear a tensile force, for example, made of a cable material, a rod, or the like. The first ring portion 53 is annular when viewed from the vertical direction. The second end portions 51b of the plurality of main cables 51 are respectively connected to the first ring portion 53. The main cable 51 may be fastened or joined to the first ring portion 53, or may be hooked and connected to the first ring portion 53.

[0028] The first ring portion 53 is located below the second ring portion 54. Between the first ring portion 53 and the second ring portion 54, a bundled member 61 (hereinafter referred to as the first bundled member 61) and a diagonal member 63 are provided. The first bundled member 61 extends in the vertical direction, the lower end portion is joined to the connection portion between the first ring portion 53 and the main cable 51, and the upper end portion is joined to the connection portion between the second ring portion 54 and the upper chord member 52. As shown in FIGS. 4 and 5, the first bundled member 61 is formed to have a length corresponding to the distance between the first ring portion 53 and the second ring portion 54. The diagonal member 63 extends in an oblique direction gradually inward in the radial direction from the lower side to the upper side, the lower end portion is joined to the connection portion between the first ring portion 53 and the main cable 51, and the upper end portion is joined to the second ring portion 54. The upper end portion of the diagonal member 63 is joined to the second ring portion 54 inside the radial direction from the connection portion between the second ring portion 54 and the upper chord member 52. As shown in FIGS. 4 and 5, the diagonal member 63 is formed to have a length corresponding to the distance between the first ring portion 53 and the second ring portion 54.

[0029] A bundled member 62 (hereinafter referred to as the second bundled member 62) is provided between the intermediate portion in the radial direction of the main cable 51 and the intermediate portion in the radial direction of the upper chord member 52. The second bundled member 62 extends in the vertical direction, the lower end portion is joined to the main cable 51, and the upper end portion is joined to the upper chord member 52. As shown in FIGS. 4 and 5, the second bundled member 62 is formed to have a length corresponding to the distance between the main cable 51 and the upper chord member 52.

[0030] A sub-cable 65 is provided between the connection portion of the main cable 51 and the first ring portion 53 and the connection portion of the upper chord member 52 and the second bundled member 62. A sub-cable 66 is provided between the connection portion of the upper chord member 52 and the second ring portion 54 and the connection portion of the main cable 51 and the second bundled member 62.

[0031] As shown in FIGS. 6 and 7, the three-dimensional cable 56 is installed between the lower end portion 61a of the first bundled member 61, the upper chord member 52 to which the first bundled member 61 is joined, and the upper end portion 62b of the second bundled member 62 joined to the upper chord member 52 adjacent in the circumferential direction, and between the lower end portion 62a of the second bundled member 62 and the upper end portion 61b of the first bundled member 61 joined to the upper chord member 52 adjacent in the circumferential direction to the upper chord member 52 to which the second bundled member 62 is joined. Further, the three-dimensional cable 56 is also installed between the lower end portion 62a of the second bundled member 62 and the first end portion 52a (outer peripheral side end portion) of the upper chord member 52 adjacent in the circumferential direction to the upper chord member 52 to which the second bundled member 62 is joined. The three-dimensional cable 56 is provided to maintain the horizontal rigidity of the cable-stayed truss portion 5. The three-dimensional cable 56 may be appropriately installed between the main cables 51 adjacent in the circumferential direction and the upper chord members 52 adjacent in the circumferential direction above them.

[0032] As shown in FIGS. 6 and 7, the membrane portion 7 has a membrane material 71 stretched over the cable-stayed truss portion 5 and a pressing cable 72 joined to the cable-stayed truss portion 5 to press the membrane material 71. The membrane material 71 is provided on the upper chord member 52, the second ring portion 54, and the three-dimensional cable 56. The pressing cable 72 is fixed to the cable-stayed truss portion 5 and a predetermined tension is introduced. The membrane material 71 is maintained in a stretched state by being pressed by the pressing cable 72. One membrane material 71 may be provided between the upper chord members 52 adjacent in the radial direction.

[0033] As shown in FIG. 2, the additional structural member 8 is a member that connects the cable-stayed truss portion 5 and the lower structure 3. In the present embodiment, a retraction cable 81 and an additional structural cable 82 are provided as the additional structural member 8. The leading-in cable 81 has one end 81a joined to the lower structure 3 and the other end 81b joined to the joint portion of the upper chord member 52 and the second bundled member 62. The leading-in cable 81 extends obliquely upward from one end 81a toward the other end 81b and is provided in a tensioned state. The leading-in cable 81 is provided so as to pull the upper chord member 52 downward and radially outward. The additional structure cable 82 has one end 82a joined to the outer peripheral steel frame portion 4 and the other end 82b joined to the lower end portion 62a of the second bundled member 62. The additional structure cable 82 extends in the radial direction when viewed from the vertical direction and is provided in a tensioned state. The leading-in cable 81 is provided so as to pull the upper chord member 52 radially outward. In the present embodiment, the additional structure cable 82 and the outer peripheral steel frame portion 4 connect the arch truss portion 5 and the lower structure 3. The additional structure member 8 may be in a form other than the above-described leading-in cable 81 and additional structure cable 82 as long as it is configured to connect the arch truss portion 5 and the lower structure 3 directly or via the outer peripheral steel frame portion 4. Further, it may be made of a material other than a cable.

[0034] When an initial tension is introduced into the plurality of main cables 51 in the roof structure 1 according to the present embodiment, the first ring portion 53 is also tensioned, and the main cables 51, the first ring portion 53, the upper chord member 52, the second ring portion 54, the first bundled member 61, the second bundled member 62, and the diagonal member 63 construct a stable self-balanced wheel-shaped arch beam structure. Then, sub-cables 65, 66, a three-dimensional cable 56, etc. are provided as other structural materials effective for additional loads in this stable self-balanced wheel-shaped arch beam structure. Then, the arch truss portion 5 of the stable self-balanced wheel-shaped arch beam structure is connected to the lower structure 3 via the outer peripheral steel frame portion 4, and the arch truss portion 5 and the lower structure 3 are connected by the additional structure member 8.

[0035] The roof structure 1 is set as follows with respect to the acting uplift wind pressure. For a small uplift wind pressure below a predetermined value, until the tension of the main cable 51 and the first ring portion 53 disappears, as shown in FIG. 8, a compressive force is transmitted from the first ring portion 53 to the main cable 51, and mainly due to the initial tension of the main cable 51, it resists the uplift wind pressure. For a large uplift wind pressure exceeding the predetermined value and causing the tension of the first ring portion 53 to disappear, as shown in FIG. 9, mainly the upper chord member 52, the second ring portion 54, the first bundled member 61, the second bundled member 62, the diagonal member 63, the sub-cables 65, 66, the three-dimensional cable 56, and the additional structural member 8 naturally switch to resist the uplift wind pressure. At this time, by pulling the draw-in cable 81, it is possible to resist the uplift load. Therefore, a tension that can resist a small uplift wind pressure below a predetermined value is introduced into the main cable 51, and an excessive initial tension is not required.

[0036] The roof structure 1 according to this embodiment is constructed as follows. First, a plurality of main cables 51, the first ring portion 53, a plurality of upper chord members 52, the second ring portion 54, the first bundled member 61, the second bundled member 62, and the diagonal member 63 between the plurality of main cables 51 and the plurality of upper chord members 52 are assembled into a temporary state without introducing tension into the main cable 51. In the above temporary state, sub-cables 65, 66, the three-dimensional cable 56, etc. are not provided.

[0037] As shown in FIG. 10, the cable-supported truss portion 5 in the above temporary state is installed on the first temporary gantry 91 and the second temporary gantry 92. The first end portion 52a of the upper chord member 52 is placed on the first temporary gantry 91, and the second end portion 52b of the upper chord member 52 is placed on the second temporary gantry 92. Members other than the upper chord member 52 are in a state of being suspended and supported by the upper chord member 52. Tension is simultaneously introduced into a plurality of main cables 51 of the temporary state of the cable - stayed truss portion 5 supported by the first temporary gantry 91 and the second temporary gantry 92 to construct a self - balancing wheel - type cable - stayed beam structure. The introduction of tension into the plurality of main cables 51 can be carried out simultaneously by performing it from the side where the first ring portion 53 is joined (the second end portion 51b side of the main cable 51), and the construction time can be shortened.

[0038] As shown in FIG. 11, when tension is introduced into the plurality of main cables 51, they float upward. As the main cables 51 float upward, the first bundled member 61, the second bundled member 62, and the diagonal member 63 also float upward. The upper chord member 52 is pushed from below by the first bundled member 61, the second bundled member 62, and the diagonal member 63, and while the first end portion 52a remains placed on the first temporary gantry 91, the second end portion 52b side floats upward. As a result, the cable - stayed truss portion 5 is supported by the first temporary gantry 91 and is separated from the second temporary gantry 92. As described above, after the cable - stayed truss portion 5 constructs a self - balancing wheel - type cable - stayed beam structure, the second temporary gantry 92 is removed.

[0039] Subsequently, as shown in FIG. 12, sub - cables 65, 66, a three - dimensional cable 56, a projecting portion 67, etc. are installed on the cable - stayed truss portion 5. The cable - stayed truss portion 5 is joined and integrated with the outer peripheral steel frame portion 4 constructed simultaneously or before and after the above - mentioned process. After the cable - stayed truss portion 5 is joined to the outer peripheral steel frame portion 4, the first temporary gantry is removed.

[0040] Subsequently, the additional structural member 8 and the membrane portion 7 shown in FIG. 2 are installed. In this way, the roof structure 1 is constructed.

[0041] Next, the operation and effects of the roof structure 1 according to the above - mentioned present embodiment will be described. In the roof structure 1 according to the above-described embodiment, when an external force equal to or greater than a predetermined value at which the tension of the first ring portion 53 disappears acts on the bowstring truss portion 5, the upper chord member 52, the second ring portion 54, the first bundle member 61, the second bundle member 62, the diagonal member 63, the sub-cables 65 and 66, the three-dimensional cable 56, and the additional structural member 8 resist against the external force. Therefore, the initial tension introduced into the main cable 51 does not necessarily have to be of a magnitude capable of resisting all external forces, and it may be of a magnitude such that the bowstring truss portion 5 can construct a stable self-balancing structure. Thereby, it is not necessary to excessively introduce the initial tension into the main cable 51, and a safe structure can be realized against disturbances such as during wind loads. Also, when the bowstring truss portion 5 has an annular structure that is planar and elliptical or an annular structure with a wavy shape having a height difference as in the present embodiment, it is a less stable structure compared to a perfect circle or a shape without a height difference. Therefore, a strong bending rigidity is required for the bowstring truss portion 5. In particular, when the initial tension introduced into the main cable 51 increases, it becomes necessary to further increase this bending rigidity. In the roof structure 1 according to the present embodiment, since the initial tension introduced into the main cable 51 can be suppressed to a small value, the bending strength required even in the case of an annular structure in which the bowstring truss portion 5 is planar and elliptical or an annular structure with a wavy shape having a height difference can be suppressed. Furthermore, in the case of an annular structure in which the bowstring truss portion 5 is planar and elliptical or an annular structure with a wavy shape having a height difference, it is very difficult to stabilize it with respect to the initial tension. However, in the roof structure according to the present embodiment, it can be easily stabilized by introducing tension into the main cable 51. Also, since the roof structure 1 according to the present embodiment is a structure using cables, membranes, etc., weight reduction can be achieved.

[0042] In the roof structure 1 according to the present embodiment, a retraction cable 81 is provided as an additional structural member 8 that is joined to the bowstring truss portion 5 and is also joined to the lower structure body 3 below the bowstring truss portion 5. By adopting such a configuration, when an uplifting wind pressure acts, the stress generated in the bowstring truss portion 5 can be reduced.

[0043] Further, in the roof structure 1 according to the present embodiment, an outer peripheral steel frame portion 4 is provided on the outer periphery of the bowstring truss portion 5 and supported by the lower structure 3, and the bowstring truss portion 5 is joined to the outer peripheral steel frame portion 4. With such a configuration, it is possible to install a solar panel or the like on the roof 2 on the outer peripheral steel frame portion 4, and functions can be added to the roof 2.

[0044] Further, in the roof structure 1 according to the present embodiment, the membrane portion 7 includes a membrane material 71 stretched over the bowstring truss portion 5 and a pressing cable 72 joined to the bowstring truss portion 5 to press the membrane material 71. By doing so, since the membrane material 71 can be installed for each span and pressed by the pressing cable 72, the workability is good. Further, by introducing tension into the pressing cable 72, the membrane material 71 can be maintained in a stretched state. When the tension of the membrane material 71 is reduced due to aging deterioration, maintenance can be performed by introducing tension into the pressing cable 72.

[0045] As described above, the embodiment of the roof structure 1 according to the present invention has been described. However, the present invention is not limited to the above embodiment and can be appropriately changed without departing from the gist thereof. For example, in the present embodiment, the planar shape of the stadium 11 is an ellipse, but it may be a shape other than an ellipse such as a perfect circle or a polygon. In the above embodiment, the bowstring truss portion 5 (roof 2) has an elliptical planar shape and a wavy shape having height differences in the circumferential direction and the radial direction. The roof 2 may have a planar shape such as a perfect circle or a polygon, or may have a shape without height differences. The arrangement of the spectator seats 13 and various rooms in the stadium 11 may be other than the above.

[0046] In the above embodiment, the lower chord member is the main cable 51 which is a cable member, but it may be composed of a rod or the like. In the above-described embodiment, the upper chord member 52 and the first ring portion 53 are made of a steel frame or the like, but they may be made of a material having a bending rigidity such as wood. The number and form of connecting members such as the first bundling member 61, the second bundling member 62, the diagonal member 63, the sub-cables 65 and 66, and the three-dimensional cable 56 provided between the main cable 51 and the upper chord member 52 may be set as appropriate.

[0047] In the above-described embodiment, the outer peripheral steel frame portion 4 is provided on the roof structure 1, but the outer peripheral steel frame portion 4 may not be provided, and the cable-stayed truss portion 5 may be directly joined to and supported by the lower structure body 3. Further, a solar panel may not be provided on the upper portion of the outer peripheral steel frame portion 4.

[0048] In the roof structure 1 according to the above-described embodiment, the membrane portion 7 has a structure including a membrane material 71 stretched over the cable-stayed truss portion 5 and a holding cable 72 for holding the membrane material 71, but other structures may also be used. In the roof structure 1 according to the above-described embodiment, the retracting cable 81 and the additional structure cable 82 are provided as additional structure members, but the additional structure members may be other than those described above.

[0049] In the roof structure 1 according to the above-described embodiment, an initial tension is introduced into the main cable 51 on the first temporary gantry 91 and the second temporary gantry 92, but the initial tension may be introduced into the main cable 51 on the ground or the like to construct the cable-stayed truss portion 5 of the self-aligning wheel-shaped cable-stayed beam structure and then lifted and joined to the lower structure body 3 or the outer peripheral steel frame portion 4.

Explanation of Reference Numerals

[0050] 1 Roof structure 2 Roof 3 Lower structure body 4 Outer peripheral steel frame portion 5 Cable-stayed truss portion 7 Membrane portion 8 Additional structure member 51 Main cable (lower chord member) 51a First end portion (one end portion) 51b Second end (the other end) 52 Top chord 52a First end (one end) 52b Second end (the other end) 53 First ring part 54 Second ring part 56 Three-dimensional cable (connection member) 61 First bundled material (connection member) 62 Second bundled material (connection member) 63 Diagonal member (connection member) 65, 66 Sub-cable (connection member) 71 Membrane material 72 Pressing cable 81 Pull-in cable (additional structure member) 82 Additional structure cable (additional structure member)

Claims

1. An annular cable - stayed truss part supported by a lower structure, An additional structural member connecting the cable - stayed truss part and the lower structure, A membrane part stretched over the cable - stayed truss part, and having, The cable - stayed truss part, A plurality of lower chords arranged radially, An annular first ring part arranged inside the plurality of lower chords in the radial direction, to which the plurality of lower chords are joined, A plurality of upper chords arranged radially above the plurality of lower chords, An annular second ring part arranged inside the plurality of upper chords in the radial direction, to which the plurality of upper chords are joined, A connecting member connecting the lower chord and the upper chord, and having, Initial tension is introduced into the lower chord so that tension is applied to the first ring part. The lower chord, the first ring part, the upper chord, the second ring part and the connecting member are supported by the lower structure in a state where a stable self - balancing structure is constructed, When the external force acting on the cable - stayed truss part becomes equal to or greater than a predetermined value and the tension in the lower chord and the first ring part disappears, the upper chord, the second ring part, the connecting member and the additional structural member are configured to resist the external force. A roof structure.

2. The additional structural member is a pull - in cable that is joined to the cable - stayed truss part and joined to the lower structure below the cable - stayed truss part. The roof structure according to claim 1.

3. It has an outer - perimeter steel - frame part provided on the outer perimeter of the cable - stayed truss part and supported by the lower structure, The cable - stayed truss part is joined to the outer - perimeter steel - frame part and supported by the lower structure via the outer - perimeter steel - frame part. The roof structure according to claim 1 or 2.

4. The membrane part, A membrane material stretched over the cable - stayed truss part, A pressing cable joined to the cable - stayed truss part for pressing the membrane material. The roof structure according to any one of claims 1 to 3.

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