Small diameter column and beam-to-brace joint structure

Abstract

To provide a joint structure for a small diameter column or beam to a brace, which can prevent interference between the joint plate at the end of the brace and the diaphragm, and thus allows the application of conventional general evaluation formulas for the strength and rigidity of the diaphragm. [Solution] A small diameter column and beam to brace joint structure 100 is provided with upper and lower diaphragms 20A, 20B at the upper end 11 and lower end 12 of a panel core 10, with an upper column 30A and a lower column 30B joined to the diaphragms 20A, 20B, and one of the columns 30 is a small diameter column whose width is smaller than the width of the panel core 10. A beam 40 is joined to the panel core 10 of different diameter columns, and a steel joint plate 60 is joined to the small diameter column 30 and the beam 40 to which the ends of a brace 50 are joined. The joint plate 60 has a first end face 62 welded to the beam 40 and a second end face 64 welded to the small diameter column 30, and a scallop 66 is provided between the first end face 62 and the second end face 64 to prevent interference with the diaphragm 20.

Description

[Technical Field]

[0001] The present invention relates to a joint structure between a small diameter column and a beam and a brace. [Background technology]

[0002] In steel-framed buildings, a column-beam joint structure may be applied in which an upper diaphragm and a lower diaphragm are provided at the upper and lower ends of a panel core that forms a panel zone, with a lower floor column (lower column) made of square steel pipe joined to the underside of the lower diaphragm, and an upper floor column (upper column) made of square steel pipe joined to the upper surface of the upper diaphragm, and at least one of the upper and lower columns is a small diameter column with a width smaller than the width of the panel core, and a steel beam is joined to the panel core to form a different diameter column.

[0003] In this beam-to-column joint structure, when the brace is pulled (attached) to the panel zone, the gusset plate or other connecting plate attached to the end of the brace may interfere with the upper or lower diaphragm. When the connecting plate at the end of the brace interferes with the diaphragm in this way, the mode (mechanism) of the diaphragm's out-of-plane bending deformation differs from the mode when there is no interference. This makes it impossible to apply conventional evaluation formulas for evaluating the diaphragm's strength and rigidity, and may require the creation of new evaluation formulas. Examples of conventional evaluation formulas include those described in Patent Documents 1 and 2.

[0004] On the other hand, the attachment position of the joint plate at the end of the brace in a column-beam joint structure is often aligned with the center of the upper flange of the beam, and in structures where the beam is eccentric, the attachment position of the joint plate may change.

[0005] Therefore, when evaluating the strength and rigidity of a diaphragm, it is necessary to create an out-of-plane bending deformation mode and evaluation formula while allowing a certain degree of freedom for the attachment position of the connecting plate at the end of the brace, which requires extremely complicated technical measures, which is undesirable.

[0006] In view of the above, there is a need for a joint structure between a small diameter column and a beam and a brace, in which a steel beam is joined to a panel core of a different diameter column, and a joining plate at the end of the brace is joined to the small diameter column and the beam, that can prevent interference between the joining plate and the diaphragm, and thus allows the application of conventional evaluation formulas for the strength and rigidity of the diaphragm.

[0007] Here, the above-mentioned Patent Document 1 proposes a method for predicting the rigidity of a diaphragm and a method for designing the plate thickness of a steel pipe column joint where the upper and lower columns have different diameters, and which predicts the rigidity of a diaphragm such as an upper through diaphragm and designs the plate thickness at a steel pipe column joint where the upper and lower columns have different diameters and are made of square steel pipe columns, such as a beam joint in a steel frame structure.

[0008] This diaphragm stiffness prediction method sets up an analytical model in which the diaphragm is divided into a plurality of polygonal elements as an analytical model of a steel pipe column joint, and each polygonal element is a trapezoidal polygonal element formed on the diaphragm by a line connecting the two central corners of the lower column that are the corners of the upper column that are closer to the center, two hypotenuses that are lines connecting each central corner with the corners at both ends of the side of the lower column that is separated from the upper column, and a line connecting the corners at both ends of the side of the lower column that is separated from the upper column, two triangular polygonal elements formed by a line common to the hypotenuse of this trapezoidal polygonal element and two lines connecting the offset center point that is the center of the width of the upper column on the side of the lower column that is parallel to the upper column offset direction to the both ends of the line common to the hypotenuse, and a hexagonal upper column-containing polygonal element that is the remaining part of the diaphragm, for a total of four polygonal elements. Each polygonal element is assumed to be rigid against bending forces and to elastically deform uniformly as a whole against shear forces, and each polygonal element is connected by a rotational spring at each boundary edge so that it can bend elastically.Furthermore, at the edge where the cross section of the upper column and the cross section of the lower column in the upper column-containing polygonal element align, axial strain is assumed to occur in the upper and lower columns.The loads acting on the analytical model are a downward load acting on the two corners of the upper column near the center, and an upward load acting on the two corners of the edge near the edge.The bending deformation in the rotational springs caused by this load in each polygonal element and the shear deformation of the polygonal element are added together, and the rigidity of the diaphragm is determined from the equilibrium conditions. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5864491 [Patent Document 2] Patent No. 5946613 Summary of the Invention [Problem to be solved by the invention]

[0010] According to the method for designing the thickness of a diaphragm in a joint between steel pipe columns of different diameters at the top and bottom described in Patent Document 1, it is possible to design the thickness of a diaphragm in a joint structure of different diameter columns with two-way eccentricity with high precision, but it does not disclose a means for preventing the above-mentioned problem, i.e., interference between the joint plate and the diaphragm.

[0011] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a joint structure between a small diameter column and a beam and a brace, in which a steel beam is joined to a panel core of a different diameter column, and a joining plate at the end of a brace is joined to the small diameter column and the beam, which can prevent interference between the joining plate and the diaphragm, and therefore allows the application of conventional general evaluation formulas for the strength and rigidity of the diaphragm. [Means for solving the problem]

[0012] In order to achieve the above object, one aspect of the joint structure of a small diameter column and a beam to a brace according to the present invention is as follows: A joint structure for a small diameter column and a beam to a brace, comprising: a steel upper diaphragm and a steel lower diaphragm at the upper end and the lower end of a steel panel core forming a panel zone; a steel lower column joined to the lower surface of the lower diaphragm; a steel upper column joined to the upper surface of the upper diaphragm; and a steel beam joined to the panel core of a different diameter column, the width of at least one of the upper column and the lower column being a small diameter column smaller than the width of the panel core; and a steel joint plate to which an end of a brace is joined is joined to the small diameter column and the beam, The joining plate is a first end surface welded to the beam and a second end surface welded to the small diameter column; A scallop is provided between the first end face and the second end face to prevent interference with the upper diaphragm or the lower diaphragm.

[0013] According to this aspect, in a joint structure between a small diameter column and a beam and a brace, in which a steel beam is joined to a panel core of a different diameter column and a joint plate at the end of a brace is joined to the small diameter column and the beam, the joint plate has a first end face welded to the beam and a second end face welded to the small diameter column, and a scallop is provided between the first end face and the second end face to prevent interference with the upper diaphragm or the lower diaphragm (both of which are, for example, through diaphragms), thereby preventing interference between the joint plate and the diaphragm.This makes it possible to apply conventional evaluation formulas for the strength and rigidity of the diaphragm.

[0014] Here, "a different diameter column, where at least one of the upper and lower columns is a small diameter column with a width smaller than that of the panel core," means a column where the lower column and the panel core have the same width (same dimensions in plan view) but only the upper column is a small diameter column, a column where the upper column and the panel core have the same width but only the lower column is a small diameter column, and a column where both the upper and lower columns are small diameter columns smaller than the panel core. Furthermore, the braces may be provided only above the beams, only below the beams, or both above and below the beams. In any case, scallops are provided on the joining plates to which the ends of the braces are joined.

[0015] The panel core can be formed from square steel pipes or a four-sided box (a joint of four steel plates), and the upper and lower columns and beams can be formed from steel sections such as H-shaped steel or square steel pipes.

[0016] In another aspect of the joint structure of the small diameter column and beam to the brace according to the present invention, The welded joint between the first end face and the beam, and the welded joint between the second end face and the small diameter column are characterized by being double-sided fillet welds or double-sided partial penetration welds.

[0017] According to this aspect, the welding joints between the first end face and second end face of the joining plate and the beam and small diameter column are double-sided fillet welds or double-sided partial penetration welds, thereby enabling the joining plate to be joined to the beam and small diameter column with high strength and good joinability.

[0018] In another aspect of the joint structure of the small diameter column and beam to the brace according to the present invention, The brace has a yield axial force: Ny that satisfies the following formula (X):

number

[0019] According to this aspect, the yield axial force of the brace: Ny is defined by formula (X) and a design axial force limit is set for the brace, thereby reducing the effect of the axial force of the brace on the diaphragm.

[0020] More specifically, the diaphragm may deform due to bending of the base of the upper column and the capital of the lower column during an earthquake, but the vertical component of the brace can mitigate this deformation. However, if the axial force of the brace becomes larger than expected, the deformation mode of the diaphragm will go beyond this and enter an unexpected deformation mode, and as a result, conventional strength and evaluation formulas cannot be applied.

[0021] Therefore, an axial force limit (upper limit) is set for the brace in formula (X), and on the assumption that an axial force below this upper limit acts from the brace, the diaphragm is set to an expected deformation mode, making it possible to apply conventional general strength formulas and evaluation formulas.

[0022] Another aspect of the joint structure of the small diameter column and beam to brace according to the present invention is as follows: The welding length between the first end face and the beam: lx, and the welding length between the second end face and the small diameter column: ly satisfy the following formula (Y):

number

[0023] According to this aspect, by setting the weld length lx between the first end face of the gusset plate and the beam and the weld length ly between the second end face and the small diameter column so as to satisfy formula (Y), a welded joint with sufficient weld strength can be formed within the range of the brace's allowable axial force in design. Here, since the welding is a double-sided fillet weld or a double-sided partial penetration weld, the weld lengths lx and ly are the weld lengths on one side. [Effects of the Invention]

[0024] As can be understood from the above explanation, according to the joint structure of the present invention between small diameter columns and beams and braces, in which a steel beam is joined to the panel core of a different diameter column and the joint plates at the ends of the braces are joined to the small diameter column and beam, interference between the joint plates and the diaphragm can be prevented, and therefore conventional general evaluation formulas can be applied to the strength and rigidity of the diaphragm. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a longitudinal cross-sectional view of an example of a joint structure between a small diameter column and a beam and a brace according to an embodiment. [Figure 2] FIG. 10 is a schematic diagram showing bending occurring at the base of the upper column and axial force occurring at the brace in a configuration in which a joining plate is joined to the upper column and beam. [Figure 3A] FIG. 10 is a longitudinal cross-sectional view of another example of a joint structure between a small diameter column and a beam and a brace according to an embodiment. [Figure 3B] FIG. 10 is a vertical cross-sectional view of yet another example of a joint structure between a small diameter column and a beam and a brace according to an embodiment. [Figure 3C] FIG. 10 is a vertical cross-sectional view of yet another example of a joint structure between a small diameter column and a beam and a brace according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an example of a joint structure between a small-diameter column and a beam and a brace according to an embodiment will be described with reference to the accompanying drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[0027] [Related embodiments of joint structure between small diameter columns and beams and braces] An example of a joint structure between a small-diameter column and a beam and a brace according to an embodiment will be described with reference to Figures 1 to 3. Here, Figure 1 is a longitudinal cross-sectional view of an example of a joint structure between a small-diameter column and a beam and a brace according to an embodiment, and Figure 2 is a schematic diagram showing bending occurring at the column base of the upper column and axial force occurring in the brace in a configuration in which a joint plate is joined to the upper column and the beam. Also, Figures 3A to 3C are all longitudinal cross-sectional views of other examples of a joint structure between a small-diameter column and a beam and a brace according to an embodiment.

[0028] The connecting structure 100 shown in the figure is a connecting structure in which a steel upper diaphragm 20A (through diaphragm) and a lower diaphragm 20B (through diaphragm) are welded to the upper end 11 and lower end 12 of a steel panel core 10 that forms the panel zone, a steel lower column 30B is welded to the lower surface 21 of the lower diaphragm 20B, a steel upper column 30A is welded to the upper surface 22 of the upper diaphragm 20A, a steel beam 40 is connected to the panel core 10, which is a small diameter column in which the width t1 of the upper column 30A is smaller than the width t2 of the panel core 10, and a steel connecting plate 60 to which the end 52 of a brace 50 is connected is connected to the small diameter column 30A and the beam 40.

[0029] In the illustrated example, the panel core 10 and the lower column 30B have the same width t2. The brace 50 in the illustrated example is a so-called tension brace that resists tensile force.

[0030] Here, instead of the upper column, the lower column may be a small diameter column, or both the upper column and the lower column may be small diameter columns. In the illustrated example, the brace 50 is disposed within the frame surrounded by the upper column 30A and the beam 40, but a separate brace may also be disposed within the frame surrounded by the lower column 30B and the beam 40. In the illustrated example, three beams 40 are joined to the panel core 10, but a beam (not shown) extending to the rear side of the page may also be joined (a configuration in which four beams 40 are joined), or two beams 40 that are perpendicular to each other may be joined, or two beams 40 that extend in the left-right direction (at a 180-degree angle) may be joined, or a configuration in which one beam 40 is joined may also be joined.

[0031] The panel core 10 is formed of a square steel pipe or a four-sided box made by welding four steel plates together. The upper column 30A and the lower column 30B are formed of shaped steel material such as square steel pipe or H-shaped steel. The beam 40 is formed of shaped steel material such as H-shaped steel.

[0032] An end 52 of the brace 50 is joined by bolting or welding to a part of a joining plate 60. The joining plate 60 is, for example, a gusset plate, and has a first end surface 62 welded to the beam 40 and a second end surface 64 welded to the upper column 30A, which is a small diameter column.

[0033] In FIG. 1, the beam 40 and the first end face 62 are welded together by double-sided fillet welding or double-sided partial penetration welding, and are joined via a weld 70A (illustration shows only one side of the double-sided weld, and there is a similar weld on the opposite side) having a weld length lx (the weld length along the X direction in FIG. 1).

[0034] In addition, the upper column 30A and the second end surface 64 are welded and joined by double-sided fillet welding or double-sided partial penetration welding, and are joined via a weld 70B (the illustration shows only one side of the double-sided weld, and there is a similar weld on the opposite side) having a weld length ly (the weld length along the Y direction in Figure 1).

[0035] A scallop 66 for preventing interference with the upper diaphragm 20A is provided between the first end face 62 and the second end face 64 of the joining plate 60. The scallop 66 in the illustrated example has a quarter-track shape, with a curved surface in part.

[0036] Here, when the joining plate 60 is welded to the beam 40 and the lower column 30B, the scallops 66 of the joining plate 60 act to prevent interference with the lower diaphragm 20B.

[0037] In this way, in the small diameter column and beam to brace joint structure 100 in which a steel beam 40 is joined to the panel core 10 of the different diameter column, and a joining plate 60 at the end 52 of the brace 50 is joined to the small diameter column 30A and the beam 40, the joining plate 60 has a first end face 62 welded to the beam 40 and a second end face 64 welded to the small diameter column 30A, and a scallop 66 is provided between the first end face 62 and the second end face 64 to prevent interference with the diaphragm 20, thereby preventing interference between the joining plate 60 and the diaphragm 20.

[0038] If the joining plate at the end of the brace interferes with the diaphragm, the mode of out-of-plane bending deformation of the diaphragm will differ from the mode when there is no interference, making it impossible to apply conventional evaluation formulas for evaluating the strength and rigidity of the diaphragm, and it may become necessary to create new evaluation formulas.In contrast, in the joining structure 100 shown in the figure, the scallops 66 of the joining plate 60 prevent interference between the joining plate 60 and the diaphragm 20, making it possible to apply conventional evaluation formulas for the strength and rigidity of the diaphragm 20.

[0039] As shown in Figures 1 and 2, if the axis of the brace 50 is set at an angle θ with respect to the horizontal X-axis direction, a horizontal force H acting during an earthquake will generate an axial force N acting as a compressive force in one of the braces 50 on the left and right of the upper column 30A, and an axial force N acting as a tensile force in the other brace 50. Furthermore, the column base bending force cM of the upper column 30A will act on the upper diaphragm 20A.

[0040] Here, the joint structure 100 is designed so that the yield axial force Ny, which is the maximum value of the axial force N acting on the brace 50, satisfies the following formula (Q1).

[0041]

number

[0042] By defining the yield axial force Ny of the brace 50 by equation (Q1) and setting a design axial force limit for the brace 50, the effect of the axial force N of the brace 50 on the diaphragm 20 can be reduced.

[0043] More specifically, the diaphragm 20 may be deformed due to bending of the base and the capital of the column 30 during an earthquake, but the deformation of the diaphragm 20 can be alleviated by the vertical component of the brace 50.

[0044] For example, in Figure 2, the right-hand brace 50 reduces the pushing force caused by the column base bending cM due to an upward force of N sin θ, which is opposite to the pushing direction caused by the column base bending cM, thereby mitigating the deformation of the diaphragm 20.

[0045] However, if the axial force N of the brace 50 becomes larger than expected, the deformation mode of the diaphragm 20 will not be relaxed but will become an unexpected deformation mode, and based on this, the conventional strength formulas and evaluation formulas will no longer be applicable.

[0046] Therefore, an axial force limit (upper limit) is set on the brace 50 in equation (Q1), and assuming that an axial force N below this upper limit acts from the brace 50, the diaphragm 20 is placed in an expected deformation mode, making it possible to apply conventional general strength equations and evaluation equations to the diaphragm 20.

[0047] Using the yield axial force Ny of the brace 50 defined by formula (Q1), the weld length lx of the welded portion 70A and the weld length ly of the welded portion 70B are determined so that they satisfy the following formula (Q2).

[0048]

number

[0049] By setting the weld length: lx between the first end face 62 of the gusset plate 60 and the beam 40 and the weld length: ly between the second end face 64 and the small diameter column 30A so as to satisfy formula (Y), welds 70A, 70B can be formed that have sufficient weld strength within the range of the axial force N of the brace 50 allowed by design.

[0050] Next, another example of the joint structure according to the embodiment will be described with reference to FIGS. 3A to 3C.

[0051] The joint structure 100A shown in FIG. 3A has a configuration in which one joint plate 60A is inserted into the interior of the upper column 30A, and first end faces 62 on the left and right are welded to the left and right beams 40.

[0052] The brace 50A is, for example, a buckling-restrained brace that resists tension and compression. A through diaphragm 25 is provided midway along the upper column 30A, and the connecting plate 60A is connected to the through diaphragm 25 and also to the left and right beams 40. The connecting plate 60A has a horizontal rib 82, one end of which is connected to the through diaphragm 25, and a vertical rib 84, one end of which is connected to the beams 40.

[0053] For example, in the beam 40 made of H-shaped steel, at the position corresponding to the vertical rib 84, the vertical rib 44 is joined to the web, the upper flange, and the lower flange.

[0054] The joining plate 60A has a horizontally elongated scallop 66A that does not interfere with the entire upper diaphragm 20A.

[0055] On the other hand, the joint structure 100B shown in Figure 3B has a buckling restraint brace 50A, but rather than a joint plate that is inserted into the upper column 30A as in joint structure 100A, a joint plate 60 is joined to the end of each brace 50A as in joint structure 100, and each joint plate 60 is welded to the beam 40 and the upper column 30A via welds 70A, 70B.

[0056] In the joint structure 100B, a through diaphragm 25 is also provided at a midpoint of the upper column 30A, and the joint plate 60 has a horizontal rib 82 whose one end is joined to the through diaphragm 25 and a vertical rib 84 whose one end is joined to the beam 40, and at the position of the beam 40 made of H-shaped steel corresponding to the vertical rib 84, the vertical rib 44 is joined to the web, upper flange, and lower flange.

[0057] Furthermore, the joint structure 100C shown in FIG. 3C has a tension brace 50 similar to the joint structure 100, but differs from the joint plate 60 having the quarter-track scallop 66 in that the scallop 66C of the joint plate 60B has a triangular shape with tapered edges.

[0058] In this way, the shape of the scallops that do not interfere with the diaphragm 20 can be set in various ways.

[0059] The present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0060] 10: Panel core 11:Top edge 12: Bottom edge 20: Diaphragm (through diaphragm) 20A: Upper diaphragm (through diaphragm) 20B: Lower diaphragm (through diaphragm) 21: Bottom surface 22:Top surface 30: Pillar 30A: Upper pillar (pillar, small diameter pillar) 30B: Lower pillar (column) 40: Beam 44: Vertical rib 50: Brace (tension brace) 50A: Brace (buckling restraint brace) 52: Edge 60, 60A, 60B: Joint plate (gusset plate) 62: 1st end surface 64:Second end surface 66, 66A, 66B, 60C: Scallop 70A, 70B: Welded parts 82: Horizontal rib 84: Vertical rib 100, 100A, 100B, 100C: Joint structure of small diameter columns and beams and braces (joint structure) H: Horizontal force N: Axial force cM: Column base bending

Claims

1. A joint structure for a small diameter column and a beam to a brace, comprising: a steel upper diaphragm and a steel lower diaphragm at the upper end and the lower end of a steel panel core forming a panel zone; a steel lower column joined to the lower surface of the lower diaphragm; a steel upper column joined to the upper surface of the upper diaphragm; and a steel beam joined to the panel core of a different diameter column, the width of at least one of the upper column and the lower column being a small diameter column smaller than the width of the panel core; and a steel joint plate to which an end of a brace is joined is joined to the small diameter column and the beam, The joining plate is a first end surface welded to the beam and a second end surface welded to the small diameter column; A joint structure for a small diameter column and beam to a brace, characterized in that a scallop is provided between the first end face and the second end face to prevent interference with the upper diaphragm or the lower diaphragm.

2. 2. The joint structure for a small diameter column and a beam with a brace according to claim 1, wherein the welded joint between the first end face and the beam, and the welded joint between the second end face and the small diameter column are double-sided fillet welds or double-sided partial penetration welds.

3. The joint structure of a small diameter column and a beam with a brace according to claim 2, characterized in that the yield axial force Ny of the brace satisfies the following formula (X): [Equation 1]

4. The joining structure of a small diameter column and a beam with a brace according to claim 3, wherein the weld length between the first end face and the beam: lx and the weld length between the second end face and the small diameter column: ly satisfy the following formula (Y): [Equation 2]

Images