Seat flexion restraint muscle intersection material, structural structure

Abstract

To provide a buckling restricting brace member using wood as the buckling restricting brace member without excessively enlarging an outer diameter of the brace, having both of design and functionality, and a frame structure arranged with the buckling restricting brace member.SOLUTION: A buckling restricting brace member 1 related to the present invention comprises: a steel pipe core material 3 bearing axial force and plastically deformable; an inner stiffener 5 inserted into the core material 3 for stiffening buckling when the core material 3 receives compressive axial force; a buckling restricting part 9 structured by an outer stiffener 7 provided to cover an outer periphery part of the core material 3 for stiffening buckling when the core member 3 receives the compressive axial force; and a joint part 11 provided at an end part of the core material 3 and jointed to the column and / or the beam of a building. The inner stiffener 5 is a steel pipe or a steel bar, and the outer stiffener 7 is a hollow member formed of a wooden material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a brace member (hereinafter sometimes referred to as "brace") installed in a steel structure building, and a frame structure in which the brace member is installed. [Background technology]

[0002] Buckling-restrained braces, which prevent buckling when subjected to compressive axial force and provide the same strength and deformation performance as when subjected to tensile axial force, have been developed and put into practical use in various forms and are widely used as earthquake-resistant or vibration-damping braces. Braces, such as the double-tube brace material disclosed in Patent Document 1, which is an example of a buckling-restrained brace, mainly have a tubular buckling-restrained material that bears bending moments and a core material that is placed inside the buckling-restrained material and bears axial forces, with buckling restraint applied from the outside of the core material.

[0003] When considering the design of a buckling-restrained brace, it is desirable to keep the outer diameter of the buckling-restrained portion, which consists of a core material and buckling-restrained material, as small as possible. One possible solution to this problem is to use a hollow steel pipe as the core material and insert the buckling-restrained material inside it, as proposed in Patent Document 2 and elsewhere.

[0004] A buckling-restrained brace must satisfy the global buckling prevention condition, which requires that the design bending moment acting on the buckling-restrained member for the design axial force be less than the yield bending moment of the buckling-restrained member. This yield bending moment and the acting design bending moment are greatly affected by the outer diameter of the buckling-restrained member, and the smaller the outer diameter, the smaller the yield bending moment and the larger the acting bending moment. Therefore, it is irrational to satisfy the global buckling prevention conditions with a method of restraining buckling using steel pipes inside the core material, as in Patent Document 2, compared to a method of restraining buckling from the outside of the core material. In other words, the weight of the steel material increases, for example, by increasing the plate thickness of the buckling restraint material, and it is thought that this will increase the manufacturing costs of the brace.

[0005] In Japan, there is a tendency to prefer the warmth and design of wood grain that wood possesses, and as shown in Patent Document 3, for example, braces have been proposed that use wooden buckling restraint members instead of the conventional steel buckling restraint members. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-223415 [Patent Document 2] Japanese Patent Application Publication No. 2020-193431 [Patent Document 3] Japanese Patent Publication No. 2020-183701 Summary of the Invention [Problem to be solved by the invention]

[0007] However, as mentioned above, the bending stiffness and bending strength of the buckling-restrained material are important in the design of a buckling-restrained brace, but the Young's modulus and tensile strength of wood are approximately 1 / 10 or less of those of steel, which poses problems when using wood as a buckling-restrained material to satisfy the global buckling prevention conditions. In other words, if wood is used as a buckling-restrained material on the outer periphery of a core material so that the wood is exposed, the Young's modulus and tensile strength of wood are low, so in order to satisfy the global buckling prevention conditions, the outer diameter of the buckling-restrained material would become very large, which would impair the design. In addition, the outer diameter of the brace would become larger than the beam width, which is likely to result in disadvantages such as narrowing the interior space. On the other hand, since wood is a carbon-neutral material, demand for reducing the use of steel and utilizing wood is expected to increase.

[0008] The present invention has been made to solve these problems, and aims to provide a buckling-restrained bracing member that uses exposed wood as a buckling-restrained material without making the outer diameter of the brace excessively large, achieving both design and functionality, and a frame structure in which such a buckling-restrained bracing member is installed. [Means for solving the problem]

[0009] (1) The buckling restrained bracing member of the present invention comprises a core member made of a steel pipe capable of bearing an axial force and plastically deforming, an internal stiffener inserted into the core member to prevent buckling when the core member is subjected to a compressive axial force, a buckling restraint section made up of an external stiffener installed to cover the outer periphery of the core member to prevent buckling when the core member is subjected to a compressive axial force, and a joint provided at the end of the core member to be joined to a column and / or beam of a building, The inner stiffener is a steel pipe or a steel bar, and the outer stiffener is a hollow member made of wood.

[0010] (2) Furthermore, in the above (1), the external stiffener is characterized in that it is made up of two members divided into two in a cross-sectional direction perpendicular to the material axis, and the two members are joined by bolts or adhesive to form a tubular shape.

[0011] (3) In addition, in the above (1) or (2), the bending rigidity of the inner stiffener is greater than the bending rigidity of the outer stiffener.

[0012] (4) Furthermore, in any of the above (1) to (3), the difference between the minimum value of the gap in a cross section perpendicular to the material axis direction between the core material and the inner stiffener and the minimum value of the gap in a cross section perpendicular to the material axis direction between the core material and the outer stiffener is within 2 mm.

[0013] (5) The frame structure according to the present invention is characterized in that the buckling restraint bracing member described in any one of (1) to (4) above is arranged in a frame section consisting of columns and beams. [Effects of the Invention]

[0014] The buckling restraint brace member of the present invention comprises a core material, an inner stiffener inserted inside the core material, a buckling restraint section composed of an outer stiffener installed to cover the outer periphery of the core material, and a joint section provided at the end of the core material, and because the inner stiffener is a steel pipe or steel bar and the outer stiffener is a hollow member formed from wood material, design and functionality are achieved without making the outer diameter excessively large. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a side view of a buckling restraint brace member according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 1 is an explanatory diagram of another aspect of the buckling restraint brace member according to an embodiment of the present invention (part 1). [Figure 4] FIG. 2 is an explanatory diagram of another aspect of the buckling restraint brace member according to the embodiment of the present invention (part 2). [Figure 5] FIG. 3 is an explanatory diagram of another aspect of the buckling restraint brace member according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] As shown in Figures 1 and 2, the buckling restraint bracing member 1 of this embodiment comprises a core material 3, a buckling restraint section 9 composed of an inner stiffener 5 inserted inside the core material 3, and an outer stiffener 7 covering the outer periphery of the core material 3, and a joint section 11 provided at the end of the core material 3. Each component will be described in detail below.

[0017] <Core material> The core material 3 is formed of a steel pipe, which can bear axial force and undergo plastic deformation. In this embodiment, the core material 3 is a circular steel pipe, and when considering repeated plastic deformation, a seamless circular steel pipe made of low-yield-point steel is most desirable. However, the core material 3 is not limited to a circular steel pipe, and may also be a square steel pipe. However, circular steel pipes are more desirable because welding assembly of square steel pipes requires labor and cost, and cold-formed materials are thought to have difficulty in performing repeated plastic deformation.

[0018] <Inner stiffener> The inner stiffener 5 is a member inserted inside the core material 3 to stiffen the core material 3 against buckling when the core material 3 is subjected to a compressive axial force. The core material 3 may be a steel pipe or a steel bar. In the case of a steel pipe, it may be a round steel pipe (see Fig. 2 and Fig. 5) or a square steel pipe. In the case of a steel bar, it may be a round steel bar as shown in Fig. 3 or a square steel bar as shown in Fig. 4.

[0019] The inner stiffener 5 is not fixed to the core material 3 and is installed so as not to transmit axial force. For example, the total length of the inner stiffener 5 in the axial direction is set shorter than the core material 3 in consideration of the axial contraction of the core material 3, and the core material 3 and the inner stiffener 5 are temporarily joined at only one cross section in the axial direction by plug welding or the like, or the inner stiffener 5 is temporarily joined to only one side of the joint 11 by welding or the like. If the core member 3 is a circular steel pipe as shown in FIG. 2, it is preferable to use a circular steel pipe or round steel for the inner stiffener 5 as well, since this makes it easier to control the gap and facilitates manufacturing.

[0020] <External stiffener> The external stiffener 7 is a member that is installed to cover the outer periphery of the core material 3 in order to prevent buckling when the core material 3 is subjected to a compressive axial force. The external stiffener 7 is a hollow member with a square cross section made of wooden material. Examples of wooden material include solid wood, as well as laminated lumber, LVL, and CLT.

[0021] The outer stiffener 7 is attached after the core member 3, inner stiffener 5, and joint 11 have been assembled and integrated. This is because, since the outer stiffener 7 is made of wood, if the components were to be joined by welding with the outer stiffener 7 in place, fire curing would be necessary for the outer stiffener 7, which would increase the amount of work required for manufacturing.

[0022] The external stiffener 7 is made up of two members divided into two in a cross-sectional direction perpendicular to the material axis, and the two members are joined with bolts or adhesive to form a tubular shape. In the example shown in Figures 2 to 4, two members with a U-shaped cross section are joined together with bolts, adhesive, etc., with their openings facing each other. It is preferable to determine the pitch and diameter of the bolts used for joining, or the strength of the adhesive, by confirming the required specifications through prior experiments, etc.

[0023] In the examples shown in Figures 1 to 4, the cross-sectional shape of the hollow portion is square, but it is also possible to make the hollow portion circular to match the shape of the core material 3, as shown in Figure 5. In this case, although it requires more manufacturing effort, it has the advantage of making the gap smaller and easier to manage.

[0024] <Buckling restraint part> The buckling restraint portion 9 is composed of a core material 3 , an inner stiffener 5 inserted inside the core material 3 , and an outer stiffener 7 covering the outer periphery of the core material 3 . It is desirable that the gap si between the inner stiffener 5 and the core material 3 and the gap so between the outer stiffener 7 and the core material 3 are approximately equal. For example, if the gap si is larger than the gap so, when the core material 3 becomes plastic and its rigidity decreases, causing deflection, the outer stiffener 7 with the smaller gap and the core material 3 first come into contact, and the bending moment is transmitted only to the outer stiffener 7.

[0025] Furthermore, if gap si is significantly larger than gap so, the bending moment acting on outer stiffener 7 before core member 3 comes into contact with inner stiffener 5 will exceed the bending strength of outer stiffener 7, resulting in damage to outer stiffener 7. Therefore, in order to utilize both outer stiffener 7 and inner stiffener 5 as buckling restraint members, it is preferable to manage the gaps between them equally. Taking into account the management tolerances for the diameter and thickness of steel materials, and the manufacturing management tolerances for wooden materials, it is considered appropriate to design the difference between gap si and gap so to be approximately within 2 mm.

[0026] When both the inner peripheral surface of the core material 3 and the outer peripheral surface of the inner stiffener 5 have a circular cross section, as shown in Figure 2, the gap si between them is the same at any point in the circumferential direction. However, when the inner peripheral surface of the outer stiffener 7 has a square cross section and the outer peripheral surface of the core material 3 has a circular cross section, the gap so between them changes in the circumferential direction. Therefore, as shown in Figure 2, the minimum value is used for the gap so. In this way, when the gap changes in the circumferential direction depending on the cross-sectional shape, the minimum value is used for the gap si and the gap so in this invention.

[0027] The bending moment transmitted from the core material 3 is distributed to the outer stiffeners 7 and inner stiffeners 5 in accordance with the bending rigidity of the outer stiffeners 7 and inner stiffeners 5, i.e., the ratio of the product of their Young's modulus and their moment of inertia. Generally, steel materials are of more stable quality and are tougher than wood materials, and are less likely to break immediately after reaching the yield bending moment. Therefore, if the bending rigidity of the inner stiffener 5 is designed to be greater than that of the outer stiffener 7, and the inner stiffener 5 made of steel bears a greater bending moment, the brace will have better redundancy.

[0028] <Joint part> The joints 11 are members provided at both ends of the core material 3 and joined to the columns and / or beams of a building. As shown in FIG. 1, the joint 11 is formed of a cross-shaped steel material.

[0029] According to the buckling restraint bracing member 1 of this embodiment configured as described above, wood can be used in its exposed form as a buckling restraint material without excessively increasing the outer diameter of the brace, thereby achieving both design and functionality.

[0030] By disposing the buckling restraint bracing member 1 according to the present embodiment described above in a frame section consisting of columns and beams, a frame structure equipped with the buckling restraint bracing member 1 can be constructed. By including the buckling restrained bracing member 1 of this embodiment in such a frame structure, both design and functionality can be achieved as a frame structure. [Example]

[0031] In order to verify the effectiveness of the present invention, a trial design of a buckling restrained brace was attempted, which will be described below. For simplicity, the joints 11 between the columns and beams were omitted, and the specifications that satisfy the overall buckling prevention conditions were calculated for only the buckling restraint portions 9. The length of the buckling restraint section 9 is set to 3500 mm, and the assumed buckling length is also set to 3500 mm. The brace core material is φ127.0 mm x 9.0 mm, and the design axial force is 900 kN. The external stiffener 7 is made of wood and has a hollow cross-sectional shape of square, and the Young's modulus of wood is 10000 N / mm 2 , tensile strength 42N / mm 2 The Young's modulus of steel is 205,000 N / mm 2 , yield stress 325N / mm 2 The conditions for preventing global buckling are theoretically expressed by the following formula (1) or (2). Equation (1) is for the conventional example with only an outer stiffening tube, and equation (2) is for the example of the present invention.

[0032]

number

[0033] Table 1 shows the results of a trial design that satisfies the above formula. d / N EAs is clear from the above equation, when approaches 1.0, the deflection and bending moment caused by slight differences in the gap and initial imperfections change significantly, causing instability. d / N E A constraint of ≦0.8 is set.

[0034] [Table 1]

[0035] As shown in Table 1, it can be seen that the outer diameter of the external stiffener 7 is smaller in the case of the present invention. In other words, by applying the present invention, it is possible to realize a brace that is slimmer and looks better than a brace in which only the outer periphery of the core material 3 is stiffened with wood, while still leaving the wood material exposed. [Explanation of symbols]

[0036] 1 Buckling-restrained bracing members 3 Core material 5 Internal stiffener 7 External stiffener 9 Buckling restraint part 11 Joint

Claims

1. The structure comprises a core member made of a steel pipe that can bear an axial force and undergo plastic deformation, an internal stiffener inserted into the core member to prevent buckling when the core member is subjected to a compressive axial force, a buckling restraint section made up of an external stiffener installed to cover the outer periphery of the core member to prevent buckling when the core member is subjected to a compressive axial force, and a joint provided at the end of the core member to be joined to a column and / or beam of a building, A buckling restraint brace member characterized in that the inner stiffener is a steel pipe or steel bar, the outer stiffener is a hollow member formed from wood material, and the difference between the minimum value of the gap in a cross section perpendicular to the material axis direction between the core material and the inner stiffener and the minimum value of the gap in a cross section perpendicular to the material axis direction between the core material and the outer stiffener is within 2 mm.

2. The buckling restraint brace member according to claim 1, characterized in that the external stiffener is made up of two members divided into two in a cross-sectional direction perpendicular to the member axis, and the two members are joined with bolts or adhesive to form a tubular shape.

3. 3. The buckling restraint brace member according to claim 1, wherein the inner stiffener has a bending stiffness greater than the bending stiffness of the outer stiffener.

4. A frame structure, characterized in that the buckling restraint bracing member according to claim 1 or 2 is disposed in a frame section consisting of columns and beams.

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