JP2007077745A - Framework connection component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a component to connect framework structural members together, which component absorbs the impacts of external forces applied to structural frameworks and improves their deformation abilities for external force energies applied. <P>SOLUTION: The framework connection component 10 is installed between the fixing parts 2 installed on the surfaces of two framework members 1 to be connected together. It is provided with a connection part 3 that bends by external forces applied to the framework. The connection part 3 rises from the fixing part 2, and a viscoelastic material 6 is provided within a clearance 4 between the connection part 3 and the framework members 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a frame joint component, and more particularly, to a frame joint component that joins frame components to each other.

  The structure covering the space resists the weight of the structure and the outer skin attached to the structure and the load applied from the outside. In general, the structure forms a frame made up of frame components and protects the internal space from collapsing. For example, in a human body, a framework component member composed of bones is combined to form a framework called a skeleton, supports the weight, resists loads applied to the human body due to exercise or collision, and the internal space of the human body such as the brain, lungs, and internal organs Protect it from collapsing. Also, for example, in a building, a frame component consisting of columns and beams is combined to form a frame, supporting the weight of the building such as the frame component and finishing material, and resisting external forces such as earthquakes, typhoons, and snowfall. And protect the internal space of the building from collapsing. Here, the building is a general term for a structure that artificially covers a space, such as a building, a civil engineering structure, or a workpiece.

  Such a frame component member is generally a wire having a certain cross-sectional shape, and is composed of a linear or curved member. Therefore, a frame component member requires a frame joint component for joining such members to each other. For example, in the case of a human body, a joint that joins bones corresponds, but a joined part between fractured bones and a joined part between a reinforcing material and a bone are also included in the framework joined parts. Moreover, in a building, all the members which resist external force, such as a pillar, a beam, a brace, a small beam, a stud, etc. are contained in a frame structural member, for example. In addition, not only for joints between columns or beams, but also for joints between columns and beams, or for joints between columns, beams, and braces, as well as inter-column and beam joints. Also included are small beam-to-beam joints. Moreover, what is called a joint metal or a joint metal fitting is also included in the frame joint component. In addition, the structural members of the building are made of various building materials such as wood, steel frames, and concrete, and the frame joint parts are made of various building materials such as wood, metal, and plastic.

  The human body has a mechanism that deforms against external force in a joint that is a framework joint component and absorbs an impact generated by the external force. That is, an elbow joint, a knee joint, etc. are what is called a hinge structure, and one bone (joint head) fits in the other bone (glenoid fossa). There are elastic articular cartilage and a fluid such as lubricating oil on the surfaces of both of the bones that slide together, and the bones are joined together to alleviate the impact.

  In buildings, there is a highly earthquake-resistant construction in which pillars and beams, such as those in ancient Japanese five-storied pagodas, are used in combination with perforations, long presses, doughs, and elbows. In this construction method, frame-jointed parts made of wood of various shapes are combined in a complicated manner, and the construction method has a high deformability against earthquakes and the like. In addition, the frame joining parts rub against each other against an earthquake or the like to cause deformation. On the other hand, in current buildings, it is common to use bolt joining as a method of fixing the joint. Bolt holes take a certain clearance with respect to the diameters of these bolts in order to absorb construction errors. For this reason, a deformation | transformation may arise in a frame joining component because a volt | bolt slips within this clearance with respect to an earthquake etc.

  In general, in a building, deformation such as rubbing and sliding between each frame joint component with respect to external force increases the deformation capability of the building, resulting in a building with high earthquake resistance. That is, the frame-joined component becomes a kind of damper, and becomes a kind of seismic control structure that converts vibration energy such as an earthquake into heat energy or the like and attenuates it. In addition, the high deformability means that the natural period of the entire building is lengthened, resulting in a building with high earthquake resistance. That is, when the natural period is lengthened, the entire building slowly shakes with respect to an earthquake or the like, resulting in a kind of seismic isolation structure that softens the impact such as an earthquake.

  On the other hand, for example, Patent Document 1 discloses a wooden structure fitting, Patent Document 2 discloses a vibration damping damper for a wooden house using a superplastic alloy, and Patent Document 3 discloses a viscoelastic material damper. An attached wooden house seismic reinforcement structure is disclosed.

  FIG. 9 shows an outline of a wood-structured joint fitting disclosed in Patent Document 1. Metal parts 14 and 15 are fixed to the wood parts 11 and 12 of the joint part, and U-shaped leaf springs 18 that engage with the rings 16 and 17 of the respective metal parts are provided. The leaf springs are urged by the compression coil springs 20 in the direction of pulling together the wooden members that contract by natural drying. Even if an external force acts in the direction in which the wooden members are separated, the load is received as a rigid body by the wedge engaging plate 19 and the compression coil spring 20 that engage with the metal fittings 16 and 17.

  For the damping damper disclosed in Patent Document 2, a superplastic alloy such as a low yield point steel having a small yield load and excellent deformability is used. This yields low yield point steel against earthquakes and absorbs energy such as earthquakes by non-linear behavior associated with load history. That is, using a superplastic alloy such as low yield point steel is a method of absorbing vibration energy by plasticizing by deformation with respect to external force by intentionally providing a portion having low joint strength.

  The viscoelastic material used in the viscoelastic damper disclosed in Patent Document 3 refers to a polymer material that has a mechanical behavior that combines a fluid-like viscosity and a spring-like elasticity. It is also used for laminated rubber. When stress is applied to this viscoelastic material, energy such as earthquake is absorbed by non-linear behavior associated with the load history. That is, incorporating a viscoelastic material into the joint is a method of absorbing vibration energy by plasticizing due to deformation with respect to external force by intentionally providing a viscoelastic material having viscosity as described above.

JP 2004-143893 A JP-A-2005-42403 JP 2000-160683 A

  In order to transmit external force, the frame joining component that joins the frame constituting members is required to have a joint strength equal to or higher than the member strength of the frame constituting member. In general frame joint parts, a large deformation in a part with respect to external force means that an excessive stress is generated in a part of the part. It means that there is a shortage. That is, generally, the joint strength and deformation ability of the frame joint component are in a contradictory relationship. Therefore, it is difficult to increase the deformation capacity of the entire building while securing the joint strength with a normal frame joint component. In addition, slipping of the bolt joint portion due to an earthquake or the like may cause a poor tightening due to the bolt, and the occurrence thereof is uncertain.

  Moreover, although the wooden joint fitting disclosed in Patent Document 1 is deformed so as to draw the wooden members together, it functions as a rigid body when an external force such as an earthquake acts. In other words, this disclosed technique has a structure that does not allow deformation of the joint hardware, and it is difficult to absorb the impact caused by the external force applied to the framework of the structure and increase the deformation capacity of the entire building.

  In addition, the use of a superplastic alloy such as low yield point steel for the frame joint component disclosed in Patent Document 2 is limited to a portion that does not expect joint strength when an external force is applied. It is difficult to use as a frame joint component that requires a joint strength equal to or higher than the member strength.

  Furthermore, incorporation of a viscoelastic material into a frame joint component disclosed in Patent Document 3 is similarly limited to a portion where stress is not transmitted when an external force is applied, and is equivalent to the member strength of the frame component member. It is difficult to use as a frame joint component requiring the above-mentioned joint strength.

  The purpose of the present application is to solve the above problems, absorb the impact caused by the external force applied to the frame of the structure, increase the deformation capacity of the structure, and absorb the energy of the external force. Is to provide.

  In order to achieve the above object, a frame joint component according to the present invention is a frame joint component that joins the frame components that bear the weight of the frame and the external force applied to the frame, and is fixed to the surfaces of both frame components. And a fixing portion provided between the fixing portions and a connecting portion that can be bent and deformed by an external force applied to the frame.

  Further, in the frame joint component, the fixed portion and the connection portion are made of an integral plate material, and the connection portion preferably stands up from the fixed portion, and the gap between the connection portion and the frame component member Is preferably provided with a viscoelastic material.

  Further, the frame joining component is made of a plate material different from the fixed portion and the connecting portion, and the connecting portion is preferably erected from the fixed portion, and the connecting portion, the fixed portion, and the frame component member It is preferable that a viscoelastic material is provided in the space between them.

  In addition, it is preferable that the frame-joined component is composed of two frame-joined components that are overlapped, and that both connecting portions face each other to store the viscoelastic material.

  Furthermore, it is preferable that the cross-sectional shape of a connection part is a substantially semicircle in these frame joining components.

  With the above-described configuration, in the frame joint component, the connecting portion provided between the fixed portions fixed to the frame component members to be bonded to each other is bent and deformed by an external force applied to the frame. As a result, a mechanism for absorbing an impact caused by an external force in the frame joint component is possible. In particular, in a building, the frame joint component becomes a kind of damper and becomes a kind of damping structure that attenuates vibration energy such as an earthquake, so that a building having high earthquake resistance becomes possible. In addition, by deforming each frame joint part of the structure, the natural period of the whole building becomes longer, the whole building slowly shakes against earthquakes, etc., a kind of seismic isolation structure that softens the impact of earthquakes, etc. Thus, a building with high earthquake resistance becomes possible.

  Further, the frame joint component is a plate material in which the fixing portion and the connecting portion are integrated, and the connecting portion stands up from the fixing portion. As a result, as will be described later, tensile force or compressive stress is generated in the plate surface of the fixed portion due to external force applied to the framework, but in the connecting portion, in addition to the tensile or compressive stress, the distance from the fixed portion rises. A bending moment is generated by multiplying the tensile or compressive stress. That is, the connecting portion is deformed by the bending moment in addition to deformation due to tensile or compressive stress. Due to the deformation of the connecting portion, a mechanism for absorbing an impact caused by an external force becomes possible. In particular, in a building, the frame joint part becomes a kind of damper and becomes a kind of damping structure that attenuates vibration energy such as an earthquake. In addition, by deforming each frame joint part of the structure, the natural period of the whole building becomes longer, the whole building slowly shakes against earthquakes, etc., a kind of seismic isolation structure that softens the impact of earthquakes, etc. Thus, a building with high earthquake resistance becomes possible.

  In addition, even if the frame joining component is a plate material different from the fixing portion and the connecting portion, the connecting portion is connected to the fixing portion, and the connecting portion is erected from the fixing portion. Will occur.

  Furthermore, the gap between the connecting portion and the frame component member, or the gap between the connecting portion, the fixing portion and the frame component member, the gap between the pair of connecting portions, that is, integrally with the deformation of the connecting portion. A viscoelastic material is provided in the moving part. As will be described later, the viscoelastic material is deformed by an external force applied to the structure, and functions as a vibration damper that absorbs energy such as an earthquake by a non-linear behavior associated with the load history. As a result, vibration energy such as an earthquake can be converted into thermal energy and attenuated.

  Moreover, the effect by this viscoelastic material is an effect of the same kind as a deformation | transformation of a connection part, and brings about a synergistic effect. With this configuration, it is possible to use a viscoelastic material that cannot be expected to have a bonding strength for a frame component that requires a bonding strength equal to or higher than the member strength of the frame component.

  As described above, according to the frame joint component according to the present invention, it is possible to absorb the impact caused by the external force applied to the frame of the structure, increase the deformability of the structure, and absorb the energy of the external force.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows the configuration of the frame joint component 10. The frame joint component 10 is composed of a fixed portion 2 fixed by bolts 5 to each surface of two frame constituent members 1 to be bonded, and a connecting portion 3 provided between the two fixed portions 2. The fixed portion 2 and the connecting portion 3 are made of an integral plate material. In addition, since the connecting portion 3 stands up from the fixed portion 2, a gap 4 is generated between the connecting portion 3 and the frame component 1.

  In this embodiment, the frame component 1 is a wooden square. The frame constituent members 1 may be joined to each other by a conventional wooden construction method such as a sitting sickle joint, or simply joined together, or may be joined apart from each other. In addition, the frame component 1 may be, for example, a human bone, and in the case of a building, for example, may be a material such as a normal steel plate, a galvanized steel plate, stainless steel, or aluminum. Moreover, the cross-sectional shape of the frame component member 1 includes, for example, a circle, a polygon, an I type, an H type, or any other frame component member 1 used in a building. Moreover, it does not ask | require whether it is a hollow material or a solid material, it is an open section or a closed section. Furthermore, it does not ask | require whether the frame structural member 1 is a linear material or a curved material.

  The fixing | fixed part 2 is fixed to the surface of the said frame structural member 1 according to the shape. In this embodiment, in FIG. 1, the example of joining by a lag screw bolt is shown according to a wooden square. In FIG. 1, the frame joining component 10 is attached to the four sides of the square member, but may be only two opposite sides. The material of the fixing portion 2 is a material used for joining ordinary frames such as a normal steel plate, a galvanized steel plate, stainless steel, and aluminum. The joining method is usually used for the framework component 1 such as a bolt joint such as a high-strength bolt, a normal bolt, a Z bolt, or a coach screw bolt, or a joint using a nail plate having a tooth-shaped projection on a flat plate. All joining methods are included. Moreover, the shape of the fixing | fixed part 2 becomes a flat plate, a curved-surface board, etc. according to the cross-sectional shape of the frame structural member 1. FIG.

  In the present embodiment, the connecting portion 3 has a substantially semicircular shape. FIG. 2 shows an example of another embodiment of the shape of the connecting portion 3. The connecting portion 3 may be mountain-shaped as shown in the figure, or may be elliptical. That is, as long as it stands up from one fixed part 2 and also stands up from the other fixed part 2, the shape between them is arbitrary. Accordingly, the shape of the connecting portion 3 is a three-dimensional curved plate or the like according to the cross-sectional shape of the fixed portion 2.

  FIG. 3 illustrates the stress generated in the fixed portion 2 and the connecting portion 3 of the frame joint component 10 when a member force (tensile force T and bending moment M) is applied to the frame component member 1. Stresses of Ft1 = T / 2 + M / d and Ft2 = T / 2−M / d are generated in the fixing portions 2 on both sides of the frame constituent member 1 through the connecting bolts, respectively. Here, d is the distance between the centers of the thicknesses of the fixing portions 2 on both sides. An arbitrary bending moment of Ft1 (or Ft2) × L is generated in an arbitrary element of the connecting portion 3. Here, L is the distance from the center of the plate thickness of the fixed portion 2 to the center of any element of the connecting portion 3. Accordingly, each element of the connecting portion 3 is deformed by this additional bending moment in addition to the axial deformation by the tensile force Ft (or the compressive force Fc).

  In the frame joint component 10, the fixed portion 2 and the connecting portion 3 can be made to have the same thickness by design. Since the connecting portion 3 receives an additional bending moment in addition to the tensile force Ft (or compressive force Fc) generated in the fixed portion 2, a member cross section that can withstand these resultant forces is required. However, the fixing portion 2 must have a member cross-section in consideration of the deficiency of the bolt hole with respect to the tensile force for joining with the frame constituent member 1. In the connection part 3, since it stands up from the fixing | fixed part 2, it is not necessary to consider this defect | deletion for bolt joining. Therefore, the fixed portion 2 and the connecting portion 3 can be made of the same thickness without impairing the economy.

  From this, it is clear that when an external force is applied, a large deformation due to a bending moment occurs in the connecting portion 3, but the joining strength of the connecting portion 3 itself is ensured. Therefore, the frame joint component 10 according to the present invention can increase the deformation capacity of the entire building while ensuring the joint strength.

  FIG. 4 schematically shows the deformation of the connecting portion 3 of the frame joint component 10 when the tensile force T and the compression force C are applied to the frame component 1. In the figure, a broken line represents before deformation, and a solid line represents after deformation. When the tensile force T is applied (FIG. 5A), the connecting portion 3 extends in the direction of the tensile force T / 2 and falls in a direction perpendicular to the tensile force due to the bending moment Mt = T / 2 × L. . On the other hand, when the compressive force C is applied (FIG. 5B), the connecting portion 3 is contracted in the direction of the compressive force C / 2, and at the same time as the tensile force due to the bending moment Mc = T / 2 × L. Swell up. Here, L is the distance from the center of the plate thickness of the fixed portion 2 to the center of any element of the connecting portion 3.

  When the gap 4 between the connecting portion 3 and the frame component 1 is filled with the viscoelastic material 6, the shape of the viscoelastic material 6 also changes following the deformation of the connecting portion 3. The frame joint component 10 is usually designed to have a strength equal to or greater than that of the frame component 1. Therefore, by design, even during an earthquake, it behaves within the elastic range and does not become plastic. On the other hand, the viscoelastic material 6 has a high deformability, and its hysteresis characteristic shows non-linearity from minute deformation, and plasticizes even if the connecting portion 3 is in the range of elastic deformation. Therefore, it functions as a damping damper that absorbs energy such as earthquakes by non-linear behavior associated with the load history.

  FIG. 5 shows another embodiment of the frame joint component 10. The frame joint component 10 includes a fixed portion 2 fixed by bolts 5 to each surface of two frame component members 1 to be bonded, and a connecting portion 3 provided between the two fixed portions 2. However, the fixing | fixed part 2 and the connection part 3 consist of another board | plate material, and the connection part 3 is connected to the fixing | fixed part 2 by welding, for example. In addition, since the connecting portion 3 stands up from the fixing portion 2, a gap 4 is generated between the fixing portion 2, the connecting portion 3, and the frame constituent member 1.

  FIG. 6 shows another embodiment of the frame joint component 10. A gap 4 formed from the mutual connecting portion 3 is generated by superimposing the two frame joining components 10 on one side of the frame constituting member 1 so that the connecting portion 3 faces each other. The fixing portions 2 of the two frame joint components 10 are overlapped and joined to the frame constituent member 1 via bolts 5.

  FIG. 7 is a schematic view of an embodiment in which a frame joint component 10 is attached to a column and beam joint of a building. In this case, the framework component 1 of the joint shown in FIG. 6 is joined in an I shape, whereas the framework component 1 is joined in a T shape. The frame joint component 10 also has a shape bent according to the T-shaped frame component 1. When an external force is applied, the bending moment becomes the dominant stress in the column and beam joints, but the frame joint component 10 functions as a fire-fired material against this bending moment and is connected as shown in the figure. A tensile force or a compressive force acts on the material 3. This tensile force or compressive force causes bending deformation in the connecting portion 3 as described above. Also in this embodiment, the connecting portion 3 may be mountain-shaped as shown in FIG. 2 or may be elliptical, and both connecting portions 3 stand from one fixed portion 2 respectively. As long as it stands up from the other fixed part 2, the shape between them is arbitrary.

  FIG. 8 is a schematic view of an embodiment in which the frame joint component 10 is attached to the end of the brace 7 at the column and beam joint of the building. When an external force is applied, an axial force is generated in the brace 7, and the axial force is transmitted to the column and beam joints. In FIG. 8, the brace 7 is attached to the brace attachment metal 9 at the end, and this brace attachment 9 is attached to the fixing part 2 of the frame joint component 10 via the pin 8. Moreover, the other fixing | fixed part 2 of the frame joining component 10 is attached to a pillar and a beam through a volt | bolt. As for both the fixing | fixed part 2, the connection part 3 is connected to the L-shape.

  When tensile force or compressive force is generated in the brace, bending deformation occurs in the connecting portion 3 as described above. Even if the connecting portion 3 is not L-shaped, if it is attached to a portion where the axial force from the brace is transmitted within the frame joint component 10, the same effect as in the present embodiment occurs. Also in this embodiment, the connecting portion 3 may be mountain-shaped as shown in FIG. 2 or may be elliptical, and both connecting portions 3 stand up from one fixed portion 2 respectively. As long as it stands up from the other fixed part 2, the shape between them is arbitrary.

It is the schematic which shows the structure of one Example of the column joint and beam joint of the frame joining component which concerns on this invention. It is the schematic which shows the structure of other embodiment of a connection part. It is explanatory drawing which shows the load state which arises in frame joining components. It is a schematic diagram which shows the deformation | transformation of a connection part. It is the schematic which shows the structure of the other Example of a column joint and a beam joint. It is the schematic which shows the structure of the other Example of a column joint and a beam joint. It is the schematic which shows the structure of embodiment which used the frame joining component for the joint of the column and the beam. It is the schematic which shows the structure of embodiment used for the edge part of the brace which attaches a frame joining component to the joint of a column and a beam. It is the schematic of the joining bracket of the wooden structure which is a prior art.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 Frame component member, 2 fixed part, 3 connection part, 4 space | gap, 5 bolt, 6 viscoelastic material, 7 brace, 8 pin, 9 brace attachment hardware, 10 frame connection parts, 11,12 wood part, 14,15 metal fittings 16, 17 Metal ring, 18 leaf spring, 19 wedge engagement plate, 20 compression coil spring.

In order to achieve the above object, a frame joint component according to the present invention is a frame joint component that joins the frame components that bear the weight of the frame and the external force applied to the frame, and is fixed to the surfaces of both frame components. A fixing portion that is attached to the fixing portion, and a plate portion that is integral with the fixing portion, and includes a connecting portion that stands up from the fixing portion and can be bent and deformed by an external force applied to the frame, and a gap between the connecting portion and the frame component member the, characterized Rukoto viscoelastic material is provided.

Further, the frame joint component according to the present invention is a frame joint component that joins the frame component members that bear the weight of the frame and the external force applied to the frame, and is fixed to and attached to the surfaces of both frame component members. And a connecting portion that is made of a plate material different from the fixing portion, stands up from the fixing portion, and can be bent and deformed by an external force applied to the frame, and a gap between the connection portion, the fixing portion, and the frame component member Is characterized in that a viscoelastic material is provided.

Further, the frame joint component according to the present invention is a frame joint component that joins the frame component members that bear the weight of the frame and the external force applied to the frame, and is fixed to the surfaces of both frame component members. And a connecting portion that is made of a plate material integral with the fixing portion, stands up from the fixing portion, and can be bent and deformed by an external force applied to the frame, and the two frame connecting parts are overlapped and opposed to each other A viscoelastic material is provided in the space between the two. The fixing portion includes a column fixing portion fixed to the surface of the column and a beam fixing portion fixed to the surface of the beam, and the connecting portion is provided between the column fixing portion and the beam fixing portion. , standing from the fixing portion, and resisted by the axial force to the bending moment occurring at the junction of the beam-to-column, bending deformable der Rukoto are preferred.

Further, the frame joint component according to the present invention is a frame joint component that joins the weight of the frame and the external force applied to the frame at the column beam joint, the column fixing part fixed to the surface of the column, and the beam surface It is provided between the beam fixing part fixed to the brace, the brace connecting part to which the end of the brace is attached, the column fixing part, the beam fixing part and the brace connecting part, and stands up from the column fixing part and the beam fixing part. A connecting portion that resists a tensile force generated in the brace and can be bent and deformed, and two frame joint parts are overlapped with each other, and a viscoelastic material is provided in a gap between the opposing connecting portions. It is characterized by that. Further, the connecting portion includes a pillar fixed portion, and the beam fixing portion, Rukoto preferably provided in an L-shape between the brace fixing part.

Further, the frame joint component according to the present invention is a frame joint component that joins a column, a beam, and a brace that bear the weight of the frame and an external force applied to the frame at a joint portion of the column beam, and is fixed to the surface of the column. It is provided between the column fixing part, the beam fixing part fixed to the surface of the beam, the brace connecting part to which the end of the brace is attached, the column fixing part, the beam fixing part, and the brace connecting part. And a joint that can stand up from the beam and the beam fixing part, resists the tensile force generated in the brace, and can be deformed by bending. Is characterized in that a viscoelastic material is provided. Moreover, it is preferable that this connection part is provided in L shape between a pillar fixing | fixed part, a beam fixing | fixed part, and a brace connection part.

Claims (7)

A frame joint component that joins the frame components that bear the weight of the frame and the external force applied to the frame,
A fixing portion fixed to and attached to the surfaces of both frame components;
A connecting portion that is provided between the fixed portions and can be bent and deformed by an external force applied to the frame;
A framework joint component comprising: The frame joint component according to claim 1,
The fixed part and the connecting part are made of an integral plate material, and the connecting part stands up from the fixing part. The frame joint component according to claim 1 or 2,
A frame joint component, wherein a viscoelastic material is provided in a gap between the connecting portion and the frame component member. The frame joint component according to claim 1,
A frame joint component comprising: a fixed portion and a plate material different from the connecting portion, wherein the connecting portion stands up from the fixing portion. The frame joint component according to claim 1 or 4,
A framework joint component, wherein a viscoelastic material is provided in a gap between the connecting portion, the fixing portion, and the framework constituent member. In the frame joint component according to claim 2 or 4,
A frame-joined component in which two frame-joined components are superposed, and both connecting portions face each other to store a viscoelastic material. The frame joint component according to any one of claims 1 to 6,
The cross-sectional shape of a connection part is a substantially semicircle, The frame joining component characterized by the above-mentioned.

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