Patent Application
20230091125
The present invention relates to a post and beam structure for a wooden building where a tall opening portion is provided in an exterior wall facing a multi-height space.
A building based on a wooden post and beam structure or a similar wooden structure can have a multi-height space inside the building, with a tall window provided through upper and lower floors (a double-height window) in an exterior wall that faces the multi-height space. This design necessitates a resisting measure against wind pressure that acts on the window. Conventional techniques have taken following reinforcing structures as wind-pressure resisting measures.
[A] As shown in
[B] More than one continuous post extending through upper and lower floors is disposed upright on the interior side of a window. Each continuous post is a squared timber having dimensions of 105 mm×105 mm to 120 mm×120 mm.
[C] In two-by-four construction, Type 204 timbers (38 mm×89 mm) or Type 206 timbers (38 mm×140 mm) are used as wall frame members. Three or four such timbers are bundled, joined by nails, and disposed upright as a reinforcing post.
Additionally, PTL 1 teaches a structure for providing a large opening portion, such as a carport, in a wooden post-and-beam building frame. Although the opening portion in PTL 1 does not face a multi-height space, posts on both sides of the opening portion are disposed in such a manner that longer sides of their rectangular cross-section are oriented in a frontage direction.
PTL 1: JP 3072595 U
According to the reinforcing structure [A], the wind-resistant beam is mounted in such a manner that a weak axis direction (the shorter-side direction) of its rectangular cross-section is aligned with the direction of wind pressure acting on the window. This structure cannot provide a satisfactory strength against the wind pressure, making it difficult to allow for a large opening area for the window. Further in terms of visual appeal, this structure is undesirable because the wind-resistant beam having a considerable height interrupts the double-height window in the middle and sacrifices its vertical continuity.
According to the reinforcing structure [B], the cross-sectional area of the continuous posts is small relative to their length. Such continuous posts are limited in strength against the wind pressure and are susceptible to buckling. If the number of continuous posts and their cross-sectional area are increased to ensure a predetermined strength, spaciousness and daylighting properties of the window will be impaired.
According to the reinforcing structure [C], the cross-section of the reinforcing post is too small in the wind pressure direction to give a satisfactory strength. Since the two-by-four timber is a sawn timber, a longer timber is more susceptible to warpage or twist. In addition, when the timber member is intended as an exposed finishing member, the timber member itself is less attractive in texture and visual appeal, and less likely to add a sense of luxury.
According to PTL 1, the expected resistance of the described structure is effective against a vertical load and a horizontal load in the frontage direction, but is not effective against wind pressure acting in a direction orthogonal to the frontage plane.
The present invention is made in view of the above-mentioned problems, and intends to provide a post and beam structure that includes an opening portion, such as a tall window, facing a multi-height space, such that the post and beam structure exerts a high resistance against great wind pressure acting on the opening portion, and adds excellent spaciousness and visual appeal to the opening portion.
In order to achieve the above-mentioned object, a post and beam structure at a multi-height opening portion according to the present invention, in which the opening portion has a height of two stories or more and is provided in an exterior wall that faces a multi-height space, has following characteristics. The post and beam structure includes at least one wind-resistant post that is composed of a glued laminated timber and that has a cross-section in which a long axis dimension thereof is at least twice as long as a short axis dimension thereof. The wind-resistant post is disposed upright and extends continuously through upper and lower floors, with a long axis direction of the cross-section being orthogonal to an opening plane, and the wind-resistant post serves to resist wind pressure acting on the opening plane.
The wind-resistant post in this invention is a continuous post that extends continuously through two stories or more. The wind-resistant post having the rectangular cross-section is disposed upright, with the long axis direction of the cross-section being oriented to the direction orthogonal to the opening plane, namely, oriented to a direction of action of the wind pressure. Since the wind-resistant post is used in the strong axis orientation relative to the wind pressure, the wind-resistant post ensures a high strength and enables creation of a large and spacious opening portion.
Being processed from glued laminated timber, the wind-resistant post is uniform in strength and is less likely to develop warpage or twist, as compared to conventional common sawn timber. Further, when exposed on the interior side or the exterior side as a finishing member, the wind-resistant beam can give a beautiful and pleasing texture. Note that the glued laminated timber as used herein has a cross-section in which the long axis dimension is at least twice as long as the short axis dimension, and such a glued laminated timber is used mainly as a beam member in so-called glued laminated timber construction. Accordingly, the glued laminated timber for the wind-resistant post can be processed efficiently and economically on a conventional factory processing line.
Note that the glued laminated timber is classified into structural glued laminated timber or glued laminated timber for fixtures. The post and beam structure according to the present invention uses structural glued laminated timber. The standard for structural glued laminated timber is established as “JAS for structural glued laminated timber”, under Public Notice of the Ministry of Agriculture, Forestry and Fisheries No. 111 of 1996. According to this standard, the term “large dimension glued laminated timber” refers to glued laminated timber whose cross-section has shorter sides of 15 cm or greater and an area of 300 cm2 or greater. The term “medium dimension glued laminated timber” refers to glued laminated timber whose cross-section has shorter sides of 7.5 cm or greater and longer sides of 15 cm or greater, except the large dimension glued laminated timber. The term “small dimension glued laminated timber” refers to glued laminated timber whose cross-section has shorter sides of less than 7.5 cm or longer sides of less than 15 cm. In the present invention, the structural glued laminated timber preferable for the wind-resistant post includes the medium dimension structural glued laminated timber and the larger one.
Depending on the dimensions of the opening portion, the at least one wind-resistant post includes a plurality of wind-resistant posts that are disposed upright in the opening plane including both sides of the opening portion. When a number of wind-resistant posts are disposed, the wind-resistant posts may be linked with each other at suitable middle-height positions thereof, by at least one post connecting member that extends horizontally. Preferably, the post connecting member having a rectangular cross-section is mounted with longer sides of the cross-section being oriented vertically. Note that the cross-sectional dimensions of the post connecting member are much smaller than those of the wind-resistant posts. The position of the post connecting member can be set independently of, and is not affected by, the positions of other beam members and the like. Eventually, this arrangement is less likely to limit the freedom to design the opening portion.
Preferably, a post base of the wind-resistant post is directly fixed on a foundation via a suitable post base fitting, and a post head of the wind-resistant post is directly fixed on a pole plate, or on a similar beam member at an uppermost part of a post-and-beam building frame via a suitable post-to-beam fitting. These arrangements allow a horizontal wind pressure load to be directly transmitted to the foundation and the uppermost part of the building frame, thus achieving the stability of the building frame structure.
According to the present invention configured as described above, the post and beam structure at the multi-height opening portion includes the wind-resistant post having the rectangular cross-section and extending continuously through two stories or more. The wind-resistant post is disposed upright, with the strong axis direction of the cross-section being oriented in the direction of action of the wind pressure. This configuration gives a greater resistance against the wind pressure than the common traditional structures known as the post and beam structure and the two-by-four structure. Eventually, this configuration can increase the height and the width of the opening portion, and can permit a dynamic and spacious design of a multi-height space and a window surface.
In addition, the glued laminated timber used for the wind-resistant post ensures a greater strength and better dimensional stability than the sawn timber. When exposed as a finishing member, the wind-resistant post can give a beautiful and pleasing texture.
Considering the fact that the wind-resistant post has a greater depth (anticipated dimension) than the other parts of the framework, it is further possible to fit window-related equipment (a blind, a panel radiator, etc.) in this depth dimension.
An embodiment of the present invention is hereinafter described with reference to the drawings.
A building 1 is a two-story building, with a multi-height space provided through two stories inside. A vertically long, double-height opening portion 2 is provided in an exterior wall facing the multi-height space.
There are four wind-resistant posts 3 in total, two of them being disposed on both sides of the opening portion 2, and the other two being disposed, in this embodiment, at middle positions that divide the width of the opening portion 2 substantially equally into three parts. The wind-resistant posts 3 are composed of glued laminated timbers having a rectangular cross-section of, for example, 360 mm (long axis)×120 mm (short axis). The wind-resistant posts 3 are disposed upright, with the long axis direction of their cross-section being orthogonal to the opening plane. The cross-sectional dimensions of the wind-resistant posts 3 are not limited to the above example. For suitable strength, the long axis dimension is generally at least twice, preferably 2.5 to 3.5 times, as long as the short axis dimension.
Each of the wind-resistant posts 3 is composed of a single timber that extends continuously through the two stories. Post bases of the wind-resistant posts 3 are fixed on the foundation 4 made of reinforced concrete via suitable post base fittings 7. Post heads of the wind-resistant posts 3 are joined to the pole plates 5 via suitable post-to-beam fittings 8 such that, in this embodiment, the pole plates 5 are fitted in between the wind-resistant posts 3.
Post connecting members 9 link the wind-resistant posts 3 to each other in a horizontal direction. Cross-sectional dimensions of the post connecting members 9 are smaller than those of the wind-resistant posts 3. In this embodiment, the post connecting members 9 are composed of glued laminated timbers whose cross-section is substantially equal to, or smaller than, that of the girths 6. The post connecting members 9 are joined on side surfaces of the wind-resistant posts 3 via suitable post-to-beam fittings 10. The installation height of the post connecting members 9 is not affected by the height of a floor framing, etc. provided between the upper and lower floors, and can be suitably set at middle-height positions of the wind-resistant posts 3.
In the thus configured opening portion 2, the strong axis direction of each wind-resistant post 3 is orthogonal to the opening plane, so that the opening portion 2 can exert a high resistance against the wind pressure acting on the opening plane. This configuration permits a large and spacious design of the opening portion 2. By properly setting the cross-sectional dimensions, mutual interval, and other conditions for the wind-resistant posts 3, it is possible to increase the height of the opening portion 2 to triple-height or more.
Components such as a window sash (not shown) to be equipped in the opening portion 2 may be mounted on the exterior or interior side of the wind-resistant posts 3 or in the depth dimension of the wind-resistant posts 3. Being made of glued laminated timber, the wind-resistant posts 3 are also advantageous in being used as both interior components and exterior components. Needless to say, the surfaces of the wind-resistant posts 3 exposed on the interior side or the exterior side may be covered with a suitable finishing material.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/021587 | 6/1/2020 | WO |
