JP7520575B2 - Backstay buckling stiffening fireproof covering structure - Google Patents

Description

The present invention relates to a buckling stiffening fire-resistant covering structure for backstays.

A buckling stiffening structure for a steel brace is known (see, for example, Patent Document 1). Also, a fire-resistant coating structure for a steel brace is known (see, for example, Patent Document 2).

JP 2009-174173 A Japanese Patent Application Publication No. 9-328813

In the meantime, backstays that bear tensile forces are known in suspended structures. The backstays are arranged, for example, in a tilted (inclined) state on the outside of the suspended structure.

Here, it is possible to reduce the tilt angle of the backstay and reduce the installation space required for the backstay.

However, if the backstay tilt angle is reduced, compressive forces may act on the backstay during an earthquake, causing it to buckle.

One possible solution to this problem is to enlarge the outer dimensions of the backstay. However, enlarging the outer dimensions of the backstay may result in a decrease in the design quality of the backstay. In particular, if a backstay with an increased outer dimension is fire-resistant coated, the outer dimensions of the backstay including the fire-resistant coating will become even larger, which may decrease the design quality of the backstay.

Taking the above facts into consideration, the present invention aims to buckle and stiffen the backstay and provide fireproof coating while reducing the increase in external dimensions.

The buckling stiffening fire-resistant covering structure for a backstay in the first aspect comprises a steel backstay that is installed in an inclined state outside a structure and connected to the structure, a buckling stiffening member that has a flange portion facing the backstay and is attached to the backstay, and a fire-resistant covering member that is provided between the backstay and the flange portion and covers the backstay.

According to the buckling-stiffening fireproof covering structure for a backstay according to the first aspect , the backstay is installed in a tilted state on the outside of a structure and connected to the structure. In addition, a buckling stiffening member is attached to the backstay. By stiffening the backstay with this buckling stiffening member, buckling of the backstay is suppressed when a compressive force acts on the backstay during an earthquake.

The buckling stiffening member also has a flange portion that faces the backstay. This flange portion increases the second moment of area of the backstay. Therefore, it is possible to efficiently suppress buckling of the backstay while reducing the increase in the external dimensions of the backstay, including the buckling stiffening member.

In addition, a fire-resistant covering member is provided between the flange portion and the backstay. By covering the backstay with this fire-resistant covering member, the fire resistance performance of the backstay is improved. Furthermore, since a fire-resistant covering member such as rock wool can be filled between the backstay and the flange portion, the workability of the fire-resistant covering member is improved.

Here, the buckling stiffening member does not bear long-term loads and acts as a buckling stiffening member only during earthquakes, so fire-resistant coating can be omitted. Therefore, in the present invention, a fire-resistant coating member is provided between the flange portion and the backstay, and fire-resistant coating on the outer surface of the flange portion is omitted. As a result, in the present invention, the increase in the outer shape of the backstay, including the buckling stiffening member and the fire-resistant coating member, can be reduced compared to when the outer surface of the flange portion is fire-resistant coated.

In this way, the present invention makes it possible to buckle and stiffen the backstay while providing fireproofing while minimizing the increase in external dimensions.

The buckling stiffening fire-resistant covering structure for a backstay of the second aspect is the buckling stiffening fire-resistant covering structure for a backstay of the first aspect , which is provided with a cover member that is arranged across a pair of flange portions arranged on both sides of the backstay and covers the fire-resistant covering member.

According to the buckling stiffening fire-resistant covering structure for the backstay according to the second aspect , the cover member is disposed across a pair of flange portions disposed on both sides of the backstay to cover the fire-resistant covering member, thereby improving the design of the backstay.

In addition, costs can be reduced by using a pair of flanges as cover members.

The buckling stiffening fire-resistant covering structure for a backstay in the third aspect is the buckling stiffening fire-resistant covering structure for a backstay in the first or second aspect , in which the backstay is a flat bar inclined toward the short side in cross section.

According to the buckling stiffening fireproof covering structure for the backstay according to the third aspect , the backstay is a flat bar that is inclined toward the short side in cross section. This makes it possible to reduce the outer shape (visible width) of the flat bar as viewed from the inclination direction, thereby improving the design of the backstay.

The buckling stiffening fire-resistant covering structure for a backstay in the fourth aspect is the buckling stiffening fire-resistant covering structure for a backstay in the third aspect , in which the flange portion faces the flat bar in the thickness direction of the flat bar, and in cross-sectional view, both ends of the flange portion extend outward beyond both ends of the flat bar.

According to the fourth aspect of the buckling-stiffening fire-resistant covering structure for a backstay, the flange portion of the buckling-stiffening member faces the flat bar in the thickness direction of the flat bar. In addition, in a cross-sectional view, both ends of the flange portion extend outward beyond both ends of the flat bar. In other words, the width of the flange portion is made wider than the width of the flat bar.

By making the width of the flange section wider than the width of the flat bar in this way, it is possible to reduce the gap between the flange section and the flat bar while suppressing buckling of the flat bar, and to further reduce the external shape (visible width) of the flat bar when viewed from the tilt direction. This further improves the design of the backstay.

As explained above, according to the present invention, it is possible to buckle and stiffen the backstay and provide fireproofing while reducing the increase in external dimensions.

FIG. 1 is an elevational view showing a backstay to which a buckling stiffening fire-resistant covering structure according to this embodiment is applied. This is a cross-sectional view taken along line 2-2 of Figure 1. FIG. 3 is a cross-sectional view corresponding to FIG. 2, showing a modified example of the buckling stiffening fire-resistant covering structure of the backstay shown in FIG. 1.

The buckling stiffening fire-resistant coating structure for the backstay according to this embodiment will be explained below with reference to the drawings.

Figure 1 shows a backstay 20 to which the backstay buckling stiffening fire-resistant coating structure of this embodiment is applied. The backstay 20 is connected to the structure 10.

(Structure)
The structure 10 has a roof 12 and a pair of supports 14 that support the roof 12. The roof 12 is, for example, a steel frame or cable structure. A suspended structure is applied to this roof 12. Specifically, the roof 12 is suspended from the pair of supports 14 in a curved state that forms a downward convexity, and is supported in a suspended state by the pair of supports 14. Therefore, a tensile force acts on the roof 12.

The pair of supports 14 are formed by pillars, walls, etc. The supports 14 are arranged on both sides of the roof 12 in the erection direction, and support the roof 12. A tensile force T acts from the roof 12 on the support parts (suspension fulcrums) of the pair of supports 14 that support the roof 12. A pair of backstays 20 are arranged on the outside of the pair of supports 14 (opposite the roof 12).

(Backstay)
The pair of backstays 20 are connected to the support portions 14P of the pair of supports 14, and bear the tensile force T acting on the support portions 14P from the roof 12. Each backstay 20 is disposed in a state inclined at a predetermined inclination angle θ with respect to the vertical direction.

The tilt angle θ of the backstay 20 is generally set to about 45 degrees so that the backstay 20 functions as a tension member. However, in this embodiment, the tilt angle θ of the backstay 20 is set to less than 45 degrees in order to reduce the installation space (stance) of the backstay 20. More specifically, the tilt angle θ of the backstay 20 is set to about 15 degrees.

The tilt angle θ of the backstay 20 is preferably 40 degrees or less, and more preferably approximately 15 degrees or less, from the viewpoint of reducing the installation space required for the backstay 20.

As shown in FIG. 2, the backstay 20 is formed from a flat bar. The backstay 20 has a short side 20S1 and a long side 20S2 in cross section. The backstay 20 is inclined toward the short side 20S1 side (arrow G side) in cross section. In other words, the backstay 20 is inclined so that the outer shape (visible width) of the backstay 20 becomes narrower when viewed from the inclination direction (arrow G direction).

(Backstay buckling stiffening structure)
As shown in Fig. 1, the inclination angle θ of the backstay 20 is set to less than 45 degrees as described above. In this case, during an earthquake, a compressive force C acts on the backstay 20, and there is a possibility that the backstay 20 will buckle in the thickness direction. In particular, since the backstay 20 of this embodiment is formed of a flat bar, there is a high possibility that the backstay 20 will buckle during an earthquake. As a countermeasure to this, in this embodiment, a pair of buckling stiffening members 30 are attached to the backstay 20 as shown in Fig. 2.

(Buckling stiffening member)
The pair of buckling stiffening members 30 are each formed of a T-shaped steel. Each of the buckling stiffening members 30 has a web portion 32 and a flange portion 34 provided at an end of the web portion 32, and is formed to have a T-shaped cross section.

The pair of buckling stiffening members 30 are arranged on both sides of the backstay 20 in the thickness direction. The pair of buckling stiffening members 30 are also arranged symmetrically with respect to the backstay 20. The ends of the web portions 32 of each buckling stiffening member 30 are abutted against the surface (long side 20S2) of the backstay 20 and joined by welding or the like.

The flange portion 34 of each buckling stiffening member 30 faces the surface of the backstay 20 in the thickness direction of the backstay 20 (the direction perpendicular to the arrow G). In addition, each flange portion 34 is joined to the backstay 20 via the web portion 32.

In cross-sectional view, the width W2 of each flange portion 34 is wider than the width W1 of the backstay 20. In cross-sectional view, both ends 34E of each flange portion 34 extend outward beyond both ends 20E of the backstay 20. By attaching this pair of buckling stiffening members 30 to the backstay 20, buckling in the thickness direction of the backstay 20 is suppressed.

(Backstay fireproof covering structure)
A fire-resistant covering structure is applied to the backstay 20, and the backstay 20 is fire-resistant covered by a fire-resistant covering member 40. The fire-resistant covering member 40 is formed of, for example, rock wool. This fire-resistant covering member 40 surrounds the backstay 20 in cross-sectional view, and provides fire-resistant covering to the entire surface of the backstay 20. This improves the fire resistance of the backstay 20.

The fire-resistant covering member 40 is provided between the backstay 20 and the flange portions 34 of the pair of buckling stiffening members 30 in cross section, and covers the entire surfaces on both sides (long sides S2) of the backstay 20. In addition, a pair of cover members 50 are arranged on both sides in the direction perpendicular to the thickness direction of the backstay 20 (arrow G direction) in cross section.

The pair of cover members (fire-resistant covering covers) 50 function, for example, as a finishing material that covers the fire-resistant covering member 40. In cross-sectional view, the pair of cover members 50 are arranged across the ends 34E of a pair of opposing flange portions 34, and together with the flange portions 34, surround the backstay 20 and the fire-resistant covering member 40. In other words, the flange portions 34 of the pair of buckling stiffening members 30 also function as cover members (fire-resistant covering covers) that cover the fire-resistant covering member 40.

In cross section, a fire-resistant covering member 40 is provided between the backstay 20 and the pair of cover members 50, and the end face (short side 20S1) of the backstay 20 is covered over the entire surface with this fire-resistant covering member 40.

Here, the pair of buckling stiffening members 30 do not bear long-term loads in terms of structural design, and act as buckling stiffening members only during earthquakes, so the pair of buckling stiffening members 30 are not required to have fire resistance. For this reason, in this embodiment, the fire-resistant coating of the pair of buckling stiffening members 30 is omitted. In other words, the outer surfaces of the flange portions 34 of the pair of buckling stiffening members 30 (the surfaces opposite the backstay 20) are not fire-resistant coated and are exposed.

(Action)
Next, the operation of this embodiment will be described.

As shown in FIG. 1, according to the backstay buckling stiffening fire-resistant covering structure of this embodiment, a pair of backstays 20 are installed in a tilted state on the outside of a pair of supports 14 that constitute the structure 10, and are each connected to the support parts 14P of the pair of supports 14.

As shown in FIG. 2, a pair of buckling stiffening members 30 are attached to both sides of each backstay 20 in the thickness direction. By stiffening the backstay 20 with this pair of buckling stiffening members 30, buckling of the backstay 20 in the thickness direction is suppressed when a compressive force C (see FIG. 1) acts on the backstay 20 during an earthquake.

The pair of buckling stiffening members 30 each have a flange portion 34 that faces the surface (long side 20S2) of the backstay 20. These flange portions 34 can increase the second moment of area about the axis O of the backstay 20. Therefore, the amount of increase in the outer shape of the backstay 20 in the thickness direction, including the pair of buckling stiffening members 30, can be reduced, while efficiently suppressing buckling of the backstay 20.

A fire-resistant covering member 40 is provided between the flange portions 34 of the pair of buckling stiffening members 30 and the backstay 20 (gap). By providing a fire-resistant covering to the backstay 20 with this fire-resistant covering member 40, the fire resistance of the backstay 20 is improved. Furthermore, the fire-resistant covering member 40 can be filled between the backstay 20 and the flange portions 34, improving the workability of the fire-resistant covering member 40.

The buckling stiffening member 30 does not bear long-term loads due to its structural design, and acts as a buckling stiffening member only during earthquakes, so fire-resistant coating can be omitted. Therefore, in this embodiment, a fire-resistant coating member 40 is provided between the flange portion 34 and the backstay 20, and fire-resistant coating on the outer surface of the flange portion 34 is omitted. As a result, in this embodiment, the increase in the outer shape in the thickness direction of the backstay 20, including the buckling stiffening member 30 and the fire-resistant coating member 40, can be reduced compared to when the outer surface of the flange portion 34 is fire-resistant coated.

In this way, in this embodiment, the backstay 20 can be buckled and stiffened while providing fire-resistant coating while reducing the increase in external dimensions.

The backstay 20 is also formed of a flat bar that is inclined toward the short side 20S1 (arrow G side) in cross section. This makes it possible to reduce the outer shape (visible width) of the backstay 20 when viewed from the inclination direction (arrow G direction). This further improves the design of the backstay 20.

Furthermore, the fire-resistant covering member 40 is covered by a pair of cover members 50. This improves the design of the backstay 20. Also, each cover member 50 is arranged across the ends 34E of a pair of opposing flange portions 34, and surrounds the fire-resistant covering member 40 together with the flange portions 34. In other words, in this embodiment, the flange portions 34 of the pair of buckling stiffening members also function as cover members (fire-resistant covering covers). Therefore, in this embodiment, costs can be reduced compared to when cover members are provided separately from the flange portions 34.

Furthermore, in cross-sectional view, both ends 34E of the flange portions 34 of the pair of buckling stiffening members 30 extend outward beyond both ends 20E of the backstay 20. In other words, the width W2 of the flange portions 34 is wider than the width W1 of the backstay 20.

By making the width W2 of the flange portion 34 wider than the width W1 of the backstay 20 in this way, the distance between the flange portion 34 and the backstay 20 can be narrowed while suppressing buckling of the backstay 20, further reducing the outer shape (visible width) of the backstay 20 as viewed from the tilt direction (arrow G direction). This further improves the design of the backstay 20.

In addition, by making the width W2 of the flange portion 34 wider than the width W1 of the backstay 20, the pair of cover members 50 can be made smaller. This allows for cost reduction of the pair of cover members 50.

Generally, the suspension structure of the roof 12 is often used to create a large space. In a structure 10 having such a large space, it is difficult to form a fire compartment, and the structure 10 and the pair of backstays 20 tend to be fire-resistant structures (fire-resistant buildings) that require fire resistance. In addition, since the backstays 20 are generally installed outdoors, they need to be fire-resistant coated with rock wool or the like rather than with fire-resistant paint.

However, if the backstay 20 is fire-resistant coated with rock wool or the like and then covered with a finishing cover member (fire-resistant cover) over the rock wool, the outer shape of the backstay 20 becomes excessively large, which may reduce the aesthetic appeal (design) of the backstay 20. This embodiment is particularly effective for such fire-resistant structures.

For example, in a large-scale structure where there is sufficient design time and cost, the fire-resistant coating of the backstay 20 can be omitted by conducting a fire-resistance verification method and obtaining Ministerial certification. On the other hand, in a small-scale building where there is insufficient design time and cost, it is difficult to conduct a fire-resistance verification method and obtain Ministerial certification, and the fire-resistant coating of the backstay 20 cannot be omitted. This embodiment is also effective for such small-scale structures.

(Modification)
Next, a modification of the above embodiment will be described.

In the above embodiment, in cross-sectional view, both ends 34E of the flange portions 34 of the pair of buckling stiffening members 30 extend outward beyond both ends 20E of the backstay 20. However, the shape and size of the pair of buckling stiffening members 30 can be changed as appropriate.

For example, in the modified example shown in FIG. 3, in cross-sectional view, the width W2 of each flange portion 34 of the pair of buckling stiffening members 30 is narrower than the width W1 of the backstay 20. In addition, in cross-sectional view, both ends 34E of each flange portion 34 do not extend outward from both ends 20E of the backstay 20, but are positioned inward from both ends 20E of the backstay 20. In the modified example shown in FIG. 3, the pair of cover members 50 are larger by the amount that the width W2 of each flange portion 34 of the pair of buckling stiffening members 30 is narrower.

In this way, the shape and size of the pair of buckling stiffening members 30 can be changed as appropriate. Similarly, the shape and size of the pair of cover members 50 can also be changed as appropriate.

In the above embodiment, a pair of buckling stiffening members 30 are provided on the backstay 20. However, it is possible to omit one of the pair of buckling stiffening members 30. Also, the cover member 50 can be attached to the backstay 20 as necessary and can be omitted as appropriate.

In the above embodiment, the backstay 20 is inclined toward the short side 20S1 in the cross section. However, the inclination direction of the backstay 20 can be changed as appropriate, and for example, it may be inclined toward the long side 20S2 in the cross section.

In the above embodiment, the backstay 20 is formed from a flat bar. However, the backstay is not limited to a flat bar and may be formed from, for example, structural steel or steel pipes.

In the above embodiment, the fire-resistant covering member 40 is rock wool. However, the fire-resistant covering member 40 is not limited to rock wool, and it is also possible to use, for example, a fire-resistant board or a wrapped fire-resistant covering material.

The above embodiment is applied to the backstay 20 that supports the suspended roof 12. However, the above embodiment is not limited to the backstay 20 that supports the suspended roof 12, but can be applied to various backstays that bear tensile forces and are subjected to compressive forces during earthquakes.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and one embodiment and various modified examples may be used in appropriate combination, and the present invention may of course be embodied in various forms without departing from the spirit of the present invention.

10 Structure 20 Backstay 20E Both ends (both ends of flat bar)
20S1 Short side (short side of the cross section of the flat bar)
30 Buckling stiffening member 34 Flange portion 34E Both ends (both ends of the flange portion)
40 Fire-resistant covering member 50 Cover member

Claims (4)

A steel backstay is installed in a tilted state on the outside of the structure and connected to the structure;
A buckling stiffening member having a web portion and a flange portion that faces the backstay and is joined to the backstay via the web portion ;
A fire-resistant covering member provided between the backstay and the flange portion and covering the backstay;
A backstay buckling stiffening fire-resistant covering structure. A cover member is provided across a pair of the flange portions arranged on both sides of the backstay and covers the fire-resistant covering member.
The backstay buckling stiffening fire-resistant covering structure according to claim 1. The backstay is a flat bar inclined toward the short side in cross section.
The buckling stiffening fire-resistant covering structure for a backstay according to claim 1 or 2. The flange portion faces the flat bar in a thickness direction of the flat bar,
In a cross-sectional view, both ends of the flange portion extend outward beyond both ends of the flat bar.
The buckling stiffening fire-resistant covering structure of a backstay according to claim 3.