US20100031600A1

US20100031600A1 - Load Bearing Frame

Info

Publication number: US20100031600A1
Application number: US12/086,932
Authority: US
Inventors: Tomokazu Nakagawa; Tadao Hatanaka; Toshikazu Karatsu; Nobuo Hiura; Tetsuo Tamada; Takeshi Morii; Takeo Suga; Fumio Watanabe
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 2006-01-17
Filing date: 2006-12-27
Publication date: 2010-02-11
Also published as: TW200730701A; WO2007083505A1; JP4648203B2; JP2007191854A; CN101346520A; KR20080074226A; TWI324655B

Abstract

The present invention is to provide a load bearing frame for suppressing generation of buckling of diagonal materials and breakage of connection parts and having high deformability.

A load bearing frame 1 has two pillar materials 2 and 3, two frame materials 4 and 5 and four diagonal materials 6 to 9. A connection point 41 between the pillar material 3 and the frame material 4 is apart from a connection point 43 between the diagonal material 6 arranged on the uppermost side and the pillar material 3 by a distance L1. A connection point 48 between the pillar material 3 and the frame material 5 is apart from a connection point 47 between the diagonal material 9 arranged on the lowermost side and the pillar material 3 by a distance L2.

Description

TECHNICAL FIELD

The present invention relates to a load bearing frame used for forming a wall surface of a building.

BACKGROUND ART

A general load bearing frame is formed in a truss structure of a substantially rectangular shape in which both ends of two pillar materials are respectively connected by two frame materials, and the two pillar materials are diagonally connected by a plurality of diagonal materials (refer to Patent Documents 1 and 2 for example). Here, in the conventional load bearing frame, connection points between diagonal materials arranged on the uppermost side and the lowermost side and pillar materials correspond to corner parts of a frame. In the load bearing frame of the above structure, force is smoothly transmitted, while in the case where an excessive horizontal load is imposed, there is a problem that a stress is concentrated on the diagonal materials and connection parts so that buckling of the diagonal materials and breakage of the connection parts are generated in an earlier stage and thus deformability of the entire frame is small. In order to solve the above problem, it can be thought that strength of the diagonal materials (cross section capacity) and rigidity of the connection parts are increased. However in the above case, although a maximum load bearing capacity is increased, the deformability of the entire frame (ductility) is reduced. Therefore, there is sometimes a case where after a maximum load is obtained, the entire frame suddenly collapses. As another method for solving the above problem, it can also be thought that the connection parts between the diagonal materials and the pillar materials are brought apart in the vertical direction (refer to Patent Document 3 for example). In the load bearing frame of the above structure, in the case where the horizontal load is imposed, the diagonal materials are plastically deformed in the axial direction, and the pillar materials are also plastically deformed by bending. Therefore, the deformability of the entire frame is improved.

Patent Document 1: Japanese Patent Laid-Open No. 2002-30745 (FIG. 1)

Patent Document 2: Japanese Patent Laid-Open No. 2004-116036 (FIG. 1)

Patent Document 3: Japanese Patent No. 2942481 (FIG. 1)

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

However, in the load bearing frame of the above structure, in the case where the excessive horizontal load is imposed, the pillar materials are plastically deformed by bending. Therefore, the load bearing capacity for supporting the load in the vertical direction is extremely lowered. Consequently, the above load bearing frame cannot be used as a main structure of the building, and is only arranged in the vicinity of other pillar materials for supporting the load in the vertical direction.
A major object of the present invention is to provide a load bearing frame for suppressing generation of buckling of diagonal materials and breakage of connection parts and having high deformability.

Means for Solving the Problems

A load bearing frame according to the present invention has a first pillar material, a second pillar material, a first frame material for connecting one ends of the first pillar material and the second pillar material respectively, and a second frame material for connecting the other ends of the first pillar material and the second pillar material respectively, wherein a first diagonal material for connecting a connection position which is other than both the ends of the first pillar material and a position which is other than both the ends of the second pillar material close to the one end of the second pillar material in comparison with the connection position, and a second diagonal material for connecting a connection position which is other than both the ends of the first pillar material and a position which is other than both the ends of the second pillar material close to the other end of the second pillar material in comparison to the connection position are provided with regard to one or more connection position, and a connection point between the first diagonal material arranged closest to the one end of the second pillar material and the second pillar material is apart from a connection point between the second pillar material and the first frame material, and a connection point between the first diagonal material arranged closest to the other end of the second pillar material and the second pillar material is apart from a connection point between the second pillar material and the second frame material.
Here, the connection point between the first diagonal material and the second pillar material indicates an intersection point between an extended line of a central axis of the first diagonal material and a central axis of the second pillar material. The connection point between the second pillar material and the first frame material indicates an intersection point between a central axis of the second pillar material and a central axis of the first frame material. The connection point between the second pillar material and the second frame material indicates an intersection point between the central axis of the second pillar material and a central axis of the second frame material.
According to the above configuration, even in the case where a horizontal load (a load in the perpendicular direction to the pillar material) is imposed on the load bearing frame, the horizontal load is not directly transmitted to the diagonal materials but indirectly transmitted through the pillar materials between corner parts of a frame and the diagonal materials. Therefore, generation of an excessive stress in the diagonal materials and connection parts is suppressed. In comparison with the conventional frame in which the connection points between the diagonal materials and the pillar materials correspond to the corner parts of the frame, since rigidity of the frame is reduced so as to facilitate deformation, it is possible to prevent sudden collapse after a maximum load is obtained. Therefore, in the present invention, buckling of the diagonal material and breakage of the connection parts in an earlier stage are suppressed, and an energy absorption capacity excellent in deformability over the entire frame is obtained.
Further, in the load bearing frame according to the present invention, a distance between the connection point between the first diagonal material arranged closest to the one end of the second pillar material and the second pillar material and the connection point between the second pillar material and the first frame material, and a distance between the connection point between the first diagonal material arranged closest to the other end of the second pillar material and the second pillar material and the connection point between the second pillar material and the second frame material may be distances corresponding to 5 to 20% of the entire length of the second pillar material.
According to the above configuration, it is possible to suppress the generation of the buckling of the diagonal materials and the breakage of the connection parts in the earlier stage, and also to prevent a large decrease in a load bearing capacity of the entire frame.
Further, the load bearing frame according to the present invention may further comprise a reinforcing material for connecting a position which is other than both ends of the first frame material and a position which is other than both ends of the second frame material, the reinforcing material being jointed to the first diagonal material and the second diagonal material.
According to the above configuration, even in the case where length of the diagonal materials is longer than height of the frame (height of a rectangular frame) (in the case where a ratio between width and the height of the frame is large), it is possible to improve buckling strength of the diagonal materials. Therefore, it is possible to improve the load bearing capacity of the entire frame.
Further, the load bearing frame according to the present invention may further comprise connection members arranged between the first and second pillar materials and the first and second diagonal materials, the connection members being fixed to the first and second pillar materials at fixing positions apart from pillar corner parts of the first and second pillar materials towards the inside.
According to the above configuration, even in the case where force in the direction of leaving apart from the pillar materials is imposed on the diagonal materials, energy is absorbed by plastic deformation of the connection members. Therefore, the load bearing capacity of the entire frame is improved.
Further, in the load bearing frame according to the present invention, a distance between the pillar corner parts of the first and second pillar materials and the fixing positions may be distances corresponding to 20 to 30% of width of side surfaces of the first and second pillar materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A view showing a schematic configuration of a load bearing frame according to a first embodiment of the present invention. FIG. 1A is a front view, FIG. 1B is a bottom view and FIG. 1C is a side view.

FIG. 2 An enlarged view of the vicinity of a connection part between a pillar material and a connection member.

FIG. 3 A sectional view by line III-III of FIG. 2.

FIG. 4 A view showing a deformed state of the connection member.

FIG. 5 A view showing a schematic configuration of a load bearing frame according to a second embodiment of the present invention. FIG. 5A is a front view, FIG. 5B is a bottom view and FIG. 5C is a side view.

FIG. 6 A view showing a fixing condition and a loading condition of the frame in an evaluation test.

FIG. 7 A view showing a result of the evaluation test.

EXPLANATION OF THE REFERENCE NUMERALS

1, 01: Load bearing frame
2, 3: Pillar material
4, 5: Frame material
6, 7, 8, 9: Diagonal material
10: Connection member
102, 103: Reinforcing material

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a description will be given to preferred embodiments of the present invention with reference to drawings. FIG. 1 is a view showing a schematic configuration of a load bearing frame according to a first embodiment of the present invention. FIG. 1A is a front view, FIG. 1B is a bottom view and FIG. 1C is a side view. FIG. 2 is an enlarged view of the vicinity of a connection part between a pillar material and a connection member. Although FIG. 2 shows the vicinity of a connection part between a pillar material 3 and a connection member 10, a configuration of the vicinity of a connection part between a pillar material 2 and the connection member 10 is the same. FIG. 3 is a sectional view by line III-III of FIG. 2.
A load bearing frame 1 (hereinafter, referred to as the frame 1) shown in FIG. 1 is a steel frame for a steel house. The frame 1 has two pillar materials 2 and 3, two frame materials 4 and 5 and four diagonal materials 6 to 9. The pillar materials 2 and 3 and the frame materials 4 and 5 are quadrilateral tube members having rectangular cross sections (refer to FIG. 2). The diagonal materials 6 to 9 are members in an open cross sectional shape.
The two pillar materials 2 and 3 extend in the vertical direction and are arranged in parallel to each other with a predetermined clearance therebetween. The two frame materials 4 and 5 are horizontally arranged and connected to upper ends or lower ends of the pillar materials 2 and 3 respectively. Therefore, an outer shape of the frame 1 is formed in a substantially rectangular shape by the pillar materials 2 and 3 and the frame materials 4 and 5.
The four diagonal materials 6 to 9 connect positions which are other than the upper ends and the lower ends of the pillar materials 2 and 3 through connection members 10. Here, the diagonal materials 6 to 9 and the connection members 10 are jointed to each other by spot welding, and joint positions are shown by circle symbols in FIG. 1. The connection members 10 and the pillar materials 2 and 3 are jointed to each other by screw fastening as described later.
The diagonal materials 6 to 9 are arranged in order from the upper side to the lower side. The diagonal materials 6 and 8 are inclined so that left ends thereof are lower than right ends thereof and arranged in parallel to each other. The diagonal materials 7 and 9 are inclined so that right ends thereof are lower than left ends thereof and arranged in parallel to each other.
Further in detail, the diagonal material 6 connects a connection point 43 of the pillar material 3 apart from a connection point 41 between the pillar material 3 and the frame material 4 (an intersection point between a central axis of the pillar material 3 and a center axis of the frame material 4) to the lower side by a distance L1, and a connection point 44 of the pillar material 2 apart from a connection point 42 between the pillar material 2 and the frame material 4 (an intersection point between a central axis of the pillar material 2 and the center axis of the frame material 4) to the lower side by a distance L1+L3. Here, a state that the diagonal material 6 and the pillar material 3 are connected at the connection point 43 for example indicates a state that an intersection point between the central axis of the pillar material 3 and an extended line of a central axis of the diagonal material 6 is at the connection point 43.
The diagonal material 7 connects the connection point 44 of the pillar material 2 apart from the connection point 42 to the lower side by the distance L1+L3, and a connection point 45 of the pillar material 3 apart from the connection point 41 to the lower side by a distance L1+2×L3. Similarly, the diagonal material 8 connects the connection point 45 of the pillar material 3 apart from the connection point 41 to the lower side by the distance L1+2×L3, and a connection point 46 of the pillar material 2 apart from the connection point 42 to the lower side by a distance L1+3×L3. The diagonal material 9 connects the connection point 46 of the pillar material 2 apart from the connection point 42 to the lower side by the distance L1+3×L3, and a connection point 47 of the pillar material 3 apart from a connection point 48 between the pillar material 3 and the frame material 5 (an intersection point between the central axis of the pillar material 3 and a central axis of the frame material 5) to the upper side by a distance L2 (corresponding to a connection point of the pillar material 3 apart from the connection point 41 to the lower side by a distance L1+4×L3).
In the present embodiment, the distance L1 between the connection point 41 between the pillar material 3 and the frame material 4 and the connection point 43 between the diagonal material 6 arranged on the uppermost side and the pillar material 3 is a distance corresponding to 8.8% of the entire length of the pillar material 3. The distance L2 between the connection point 48 between the pillar material 3 and the frame material 5 and the connection point 47 between the diagonal material 9 arranged on the lowermost side and the pillar material 3 is a distance corresponding to 15.8% of the entire length of the pillar material. Here, in the case where the distances L1 and L2 are distances less than 5% of the entire length of the pillar material 3, a stress on the connection parts between the diagonal materials and the pillar materials is excessive, and thus buckling of the diagonal materials and breakage of the connection parts are generated in an earlier stage. Meanwhile, in the case where the distances L1 and L2 exceed 20% of the entire length of the pillar material 3, force transmitted to the diagonal materials is extremely small, and thus a load bearing capacity of the entire frame is largely lowered. Therefore, the distances L1 and L2 are preferably distances corresponding to 5 to 20% of the entire length of the pillar material 3.
As shown in FIG. 2, the connection member 10 is a member having a U shape cross section, and eight screw holes 10 a (refer to FIG. 3) are formed on one side surface thereof. Eight screw holes 2 a or 3 a (refer to FIG. 3) corresponding to the eight screw holes 10 a of the connection member 10 are formed at an attachment position to the connection member 10 on one side surface of the pillar material 2 or 3. Therefore, as shown in FIG. 3, in the connection member 10, screws 11 are fastened in a state that the screw holes 10 a thereof correspond to the screw holes 2 a of the pillar material 2 or the screw holes 3 a of the pillar material 3.
Provided that width of the one side surface of the pillar material 2 or 3 and one side surface of the connection member 10 is D, the connection member 10 is screwed at a position apart from both ends thereof towards the inside by a distance C. That is, the screw holes 2 a, 3 a and 10 a are formed at positions apart from pillar corner parts by the distance C. Here, the distance C between the pillar corner part and the screw fastening position is preferably a distance corresponding to 20 to 30% of the width D of an inner side surface of the pillar material 2 or 3. As mentioned above, the screw fastening of the connection member 10 at the position apart from the pillar corner part by a predetermined clearance is to absorb energy by plastically deforming the connection member 10 in the case where the force in the direction of leaving apart from the pillar material 2 or 3 (the arrow direction of FIG. 4) is imposed on the diagonal materials as shown in FIG. 4. In FIG. 4, the connection member 10 before plastic deformation is shown by a broken line, and the connection member 10 after the plastic deformation is shown by a heavy line.
Next, a description will be given to a load bearing frame according to a second embodiment of the present invention with reference to FIG. 5. FIG. 5 is a view showing a schematic configuration of the load bearing frame according to the second embodiment of the present invention. FIG. 5A is a front view, FIG. 5B is a bottom view and FIG. 5C is a side view.
A load bearing frame 101 of the second embodiment (hereinafter, referred to as the frame 101) is different from the frame 1 of the first embodiment in terms of the point that two reinforcing materials 102 and 102 are further provided. The other configuration of the frame 101 is the same as the frame 1 and thus given the same reference numerals and a detailed description thereof will be omitted.
The two reinforcing materials 102 and 103 are plate like members. The reinforcing material 102 is arranged on a near side surface of the frame 101, for connecting a central part of the frame material 4 and a central part of the frame material 5, and jointed to central parts of the diagonal materials 6 to 9. Similarly, the reinforcing material 103 is arranged on an opposite side surface of the frame 101, for connecting the central part of the frame material 4 and the central part of the frame material 5, and jointed to the central parts of the diagonal materials 6 to 9.
Next, a description will be given to an evaluation test for the frames 1 and 101 and a result thereof with reference to FIGS. 6 and 7. FIG. 6 is a view showing a fixing condition and a loading condition of the frame in the evaluation test. FIG. 7 is a view showing the result of the evaluation test and a relationship between a shear deformation angle and a horizontal load (an envelope of shear deformation angle-horizontal load curve). Here, the evaluation test is performed by repeatedly imposing the horizontal load on upper ends of the frames 1 and 101 in a state that lower ends of the frames 1 and 101 are fixed. As a comparative example, the same test is performed for the conventional frame in addition to the frames 1 and 101.
In the conventional frame, the connection parts are broken and thus the test is ended. Meanwhile, in the frame 1, the connection parts are not broken, and as seen from the test result in FIG. 6, deformability and a maximum load are largely increased in comparison to the conventional frame. In the frame 1, the diagonal materials are finally plastically buckled and the test is ended. However, in the frame 101 to which the reinforcing materials are added, not only the breakage of the connection parts but also the buckling of the diagonal materials are not generated, and hence an energy absorption capacity which is higher than the frame 1 is obtained.
As mentioned above, in the frames 1 and 101 according to the present embodiments, even in the case where the horizontal load is imposed, the horizontal load is not directly transmitted to the diagonal materials 6 to 9. The horizontal load is indirectly transmitted through the pillar materials between the corner parts of the frame and the diagonal materials (a part corresponding to between the connection point 41 and the connection point 43 of the pillar material 3, and a part corresponding to between the connection part 47 and the connection part 48 of the pillar material 3). Therefore, generation of the excessive stress in the diagonal materials 6 to 9 and the connection parts is suppressed. In comparison with the conventional frame in which the connection parts between the diagonal materials and the pillar materials correspond to the corner parts of the frame, since rigidity of the frame is reduced so as to facilitate deformation, it is possible to prevent sudden collapse after the maximum load is obtained. Therefore, in the present invention, the buckling of the diagonal materials 6 to 9 and the breakage of the connection parts in the earlier stage are suppressed, and the energy absorption capacity excellent in the deformability over the entire frame is obtained.
The frames 1 and 101 of the present invention can achieve a well-balanced energy absorption capacity for the entire frame not with a structure for absorbing the energy by plastically deforming the pillar materials by bending but by delaying the generation of the buckling of the diagonal materials and the breakage of the connection parts. Since the load bearing capacity against the load in the vertical direction is not extremely lowered, it is possible to use the frames 1 and 101 as a main structure of a building.
The distances L1 and L2 are the distances corresponding to 5 to 20% of the entire length of the pillar material 3. Therefore, it is possible to suppress the generation of the buckling of the diagonal materials and the breakage of the connection parts in the earlier stage, and also to prevent a large decrease in the load bearing capacity of the entire frame.
The frame 101 is reinforced by the reinforcing materials 102 and 103. Therefore, even in the case where the distances of the diagonal materials 6 to 9 are longer than height of the frame (height of a rectangular frame) (in the case where a ratio between width and the height of the frame is large), it is possible to improve buckling strength of the diagonal materials. Therefore, it is possible to improve the load bearing capacity of the entire frame.
The connection members 10 are screwed to the pillar materials 2 and 3 at the screw fastening positions apart from the corner parts of the pillar materials 2 and 3 towards the inside by a predetermined clearance. Therefore, even in the case where the force in the direction of leaving apart from the pillar materials 2 and 3 is imposed on the diagonal materials 6 to 9, the energy is absorbed by the plastic deformation of the connection members 10. Therefore, the load bearing capacity of the entire frame is improved.
The description is given to the preferred embodiments of the present invention above. However, the present invention is not limited to the above embodiments, and various design modifications are available within the scope of the claims. For example, although the frames 1 and 101 have the four diagonal materials 6 to 9 in the above embodiments, the number of the diagonal material may be changed. The distances L1 and L2 can also be changed.

Claims

1. A load bearing frame having a first pillar material, a second pillar material, a first frame material for connecting one ends of said first pillar material and said second pillar material respectively, and a second frame material for connecting the other ends of said first pillar material and said second pillar material respectively, wherein

a first diagonal material for connecting a connection position which is other than both the ends of said first pillar material and a position which is other than both the ends of said second pillar material close to the one end of said second pillar material in comparison with the connection position, and a second diagonal material for connecting a connection position which is other than both the ends of said first pillar material and a position which is other than both the ends of said second pillar material close to the other end of said second pillar material in comparison to the connection position are provided with regard to one or more connection position, and

a connection point between said first diagonal material arranged closest to the one end of said second pillar material and said second pillar material is apart from a connection point between said second pillar material and said first frame material, and a connection point between said first diagonal material arranged closest to the other end of said second pillar material and said second pillar material is apart from a connection point between said second pillar material and said second frame material.

2. The load bearing frame according to claim 1, wherein a distance between the connection point between said first diagonal material arranged closest to the one end of said second pillar material and said second pillar material and the connection point between said second pillar material and said first frame material, and a distance between the connection point between said first diagonal material arranged closest to the other end of said second pillar material and said second pillar material and the connection point between said second pillar material and said second frame material are distances corresponding to 5 to 20% of the entire length of said second pillar material.

3. The load bearing frame according to claim 1, further comprising a reinforcing material for connecting a position which is other than both ends of said first frame material and a position which is other than both ends of said second frame material, the reinforcing material being jointed to said first diagonal material and said second diagonal material.

4. The load bearing frame according to claim 1, further comprising connection members arranged between said first and second pillar materials and said first and second diagonal materials, the connection members being fixed to said first and second pillar materials at fixing positions apart from pillar corner parts of said first and second pillar materials towards the inside.

5. The load bearing frame according to claim 4, wherein a distance between the pillar corner parts of said first and second pillar materials and the fixing positions are distances corresponding to 20 to 30% of width of side surfaces of said first and second pillar materials.

6. The load bearing frame according to claim 2, further comprising a reinforcing material for connecting a position which is other than both ends of said first frame material and a position which is other than both ends of said second frame material, the reinforcing material being jointed to said first diagonal material and said second diagonal material.

7. The load bearing frame according to claim 2, further comprising connection members arranged between said first and second pillar materials and said first and second diagonal materials, the connection members being fixed to said first and second pillar materials at fixing positions apart from pillar corner parts of said first and second pillar materials towards the inside.

8. The load bearing frame according to claim 3, further comprising connection members arranged between said first and second pillar materials and said first and second diagonal materials, the connection members being fixed to said first and second pillar materials at fixing positions apart from pillar corner parts of said first and second pillar materials towards the inside.

9. The load bearing frame according to claim 6, further comprising connection members arranged between said first and second pillar materials and said first and second diagonal materials, the connection members being fixed to said first and second pillar materials at fixing positions apart from pillar corner parts of said first and second pillar materials towards the inside.

10. The load bearing frame according to claim 7, wherein a distance between the pillar corner parts of said first and second pillar materials and the fixing positions are distances corresponding to 20 to 30% of width of side surfaces of said first and second pillar materials.

11. The load bearing frame according to claim 8, wherein a distance between the pillar corner parts of said first and second pillar materials and the fixing positions are distances corresponding to 20 to 30% of width of side surfaces of said first and second pillar materials.

12. The load bearing frame according to claim 9, wherein a distance between the pillar corner parts of said first and second pillar materials and the fixing positions are distances corresponding to 20 to 30% of width of side surfaces of said first and second pillar materials.