Beam joint structure

Abstract

To provide a beam joining structure capable of realizing a beam joining part having sufficient yield strength without increasing the plate thickness of a joining member.SOLUTION: In the beam-joining structure 1, upper-flange joining plates 15a, 15b whose widths are gradually increased toward a first beam-upper-flange 3a side are respectively arranged on upper surfaces and lower surfaces of the first beam-upper-flange 3a and a second beam-upper-flange 5a so as to straddle the first beam-upper-flange 3a and the second beam-upper-flange 5a. An upper flange joining portion 7 in which the first beam upper flange side 15a and the second beam upper flange side 15b are respectively joined to the upper flange joining plate side 3a and the side 5a by high-strength bolts, a web joining portion 9 in which the second beam web side 5b is rigidly joined to a vertical plate 13 joined to the first beam 3, and a lower flange joining portion 11 in which the second beam lower flange side 5c is rigidly joined to the first beam lower flange side 3c or the opposing second beam lower flange side 5c are rigidly joined to each other via a member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a beam joint structure for a floor frame in a steel frame construction. [Background technology]

[0002] Conventionally, an example of a floor frame structure that supports a concrete floor of a steel-framed structure is a floor frame structure 31 as shown in Figure 11. The floor frame structure 31 is an example of a floor frame structure that is used when the beam span is large, and is equipped with girders 35 that are spanned between columns 33 and rigidly joined at both ends to the columns 33, and sub-girders 37 that are arranged perpendicular to the girders 35 and connect the juxtaposed girders 35. The girders 35 and sub-girders 37 are made of, for example, H-shaped steel.

[0003] Beam joint A, where the sub-beam 37 is joined to the main girder 35, is generally designed as a pin joint, but in some cases, beam joint A is designed as a rigid joint to suppress deflection (rotational deformation) of the sub-beam 37. Here, a rigid joint means a strong joint that does not cause rotational deformation (corners). Furthermore, sub-beams 37 are arranged on opposite sides of the main girder 35, and each is rigidly connected to the main girder 35, which is called a continuous sub-beam 39. At the rigid joints of the continuous sub-beams 39, stress (bending moment) is transmitted from one sub-beam 37 facing the main girder 35 to the other sub-beam 37, as rotational deformation is restrained.

[0004] Figure 12 shows the bending moment that occurs in the continuous beam 39 when a floor load acts on the floor frame 31 in Figure 11. Figure 12 is a diagram of the continuous beam 39 viewed from the horizontal direction, and for convenience, the continuous beam 39 is shown as a black straight line and the main beam 35 is shown as a triangle. The gray line in the figure indicates the bending moment that occurs in the continuous beam 39.

[0005] As shown in Figure 12, when a floor load 41 acts on the continuous sub-beam 39, a bending moment occurs in the longitudinal center of each sub-beam 37 that makes up the continuous sub-beam 39, with the upper end being compressed and the lower end being tensile. On the other hand, at both longitudinal ends of each of the sub-joists 37 that make up the continuous sub-joist 39, i.e., near the joints with the main girder 35, a bending moment occurs in which the upper end is tensile and the lower end is compressed. The stress that causes this upper-end tensile bending moment is greatest at the joints with the main girder 35, and is usually the maximum stress in the continuous sub-joist 39.

[0006] As described above, the rigid joint (beam joint A) between the main beam 35 and the secondary beam 37 in the floor frame 31 is subjected to large stresses that cause a tensile bending moment at the upper end, so the joint structure must be able to withstand this.

[0007] Therefore, for example, Patent Document 1 discloses an example of a beam joint structure that rigidly joins a main beam 35 and a sub-beam 37 together. In the example shown in FIGS. 6A and 6B of Patent Document 1, the upper flange 11A of the secondary beam 1A and the upper flange 21 of the main beam 2 are joined by high-strength bolts via joining members 43A and 43C. Similarly, the upper flange 11B of the sub-beam 1B and the upper flange 21 of the main girder 2 are joined by high-strength bolts via joining members 43A and 43D. The lower flange 12A of the sub-beam 1A and the lower flange 12B of the sub-beam 1B are joined to each other by high-strength bolts via joining members 41A and 41B inserted into through holes 24 formed in the web 23 of the main girder 2.

[0008] In the above example, connecting members are attached to the top and bottom surfaces of the upper flange of the sub-beam, and the upper flange of the sub-beam is rigidly connected to the upper flange of the main beam by a high-strength bolt connection with two-surface friction (double shear). In addition, connecting members are attached to the top and bottom surfaces of the bottom flanges of the sub-beams, and the bottom flanges of the sub-beams are rigidly connected to each other using high-strength bolt connections with two-surface friction (double shear).

[0009] By providing two friction surfaces as described above, the number of bolts used in high-strength bolted joints can be reduced, making it possible to reduce the size of the joint components and realize a compact beam joint, improving workability. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2022-137936 Summary of the Invention [Problem to be solved by the invention]

[0011] As described above, in the example of Figures 6A and 6B of Patent Document 1, the upper flange is rigidly joined to the main beam and the lower flange is rigidly joined to the lower flange of the opposing sub-beam by high-strength bolt joints with two-surface friction so that stress is transmitted between the upper flanges of the opposing sub-beams and between the lower flanges of the opposing sub-beams.

[0012] When beam joint A is constructed using high-strength bolt joints as in Patent Document 1, the stress acting on one sub-beam is transmitted to the other sub-beam via the bolts, joint members, and main beam, so the number of bolts and the specifications of the joint members are designed to withstand this transmitted stress. As explained in Figure 12, the stress acting on beam joint A increases the closer it is to the girder core (the widthwise center of the girder 35), and is greatest at the girder core. Therefore, conventionally, the number of bolts was designed based on the magnitude of the stress acting on the girder core, and the planar shape (width, length) of the joint member was designed according to the number of bolts.

[0013] In addition, the number of bolts connecting the connecting member to the main beam and the number of bolts connecting the connecting member to the sub-beam are generally designed to be the same. In this regard, in the example of Figures 6A and 6B of Patent Document 1, the number of bolts 44C joining the connecting members 43A, 43C to the upper flange 21 of the main beam 2 appears to be less than the number of bolts 44A joining the connecting members 43A, 43C to the upper flange 11A of the secondary beam 1A. Similarly, the number of bolts 44C joining the joining members 43A, 43D to the upper flange 21 of the main girder 2 appears to be less than the number of bolts 44B joining the joining members 43A, 43D to the upper flange 11B of the secondary beam 1B. Therefore, it is not clear whether the example of FIGS. 6A and 6B of Patent Document 1 is a joining method capable of transmitting stress equivalent to the beam strength.

[0014] Furthermore, the thickness and planar shape of the connecting member are designed based on the magnitude of the stress acting on the girder core so that the connecting member can withstand the transmitted stress. However, increasing the thickness of the joining member is not preferable because it increases the weight of the joining member and reduces workability. In addition, the strength of the connecting member can be improved by increasing the width of the connecting member, but as mentioned above, the stress acting on the connecting member increases the closer it is to the core of the main beam, so even if the width of the connecting member is increased over its entire length, the planar shape will become unnecessarily large, which is not rational. Therefore, there has been a demand for a beam joint structure that can ensure the strength of the joint members and improve the strength of the beam joint without increasing the plate thickness or unnecessarily enlarging the planar shape.

[0015] The present invention has been made to solve the above-mentioned problems, and aims to provide a beam joint structure that can achieve a beam joint with sufficient strength without increasing the plate thickness of the joint member and without unnecessarily enlarging the planar shape. [Means for solving the problem]

[0016] (1) The beam joint structure according to the present invention is a structure in which a pair of second beams, each having an H-shaped cross section and the same beam configuration as the first beam, are joined to a first beam having an H-shaped cross section in a direction perpendicular to the first beam, with the first beam sandwiched between the first beam and the second beams, an upper flange joint portion in which upper flange joint plates, the width of which gradually increases toward the first beam upper flange side, are placed on the upper and lower surfaces of the first beam upper flange and the second beam upper flange so as to straddle the first beam upper flange and the second beam upper flange, and the first beam upper flange and the second beam upper flange are respectively joined to the upper flange joint plates with high-strength bolts; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; It is characterized by having a lower flange joint portion that rigidly joins the second beam lower flange to the first beam lower flange or rigidly joins opposing second beam lower flanges to each other via a member.

[0017] (2) In addition, in the above (1), the lower flange joint portion rigidly joins the second beam lower flange to the first beam lower flange, The method is characterized in that lower flange joining plates, whose width gradually increases toward the first beam lower flange side, are placed on the upper and lower surfaces of the first beam lower flange and the second beam lower flange so as to span the first beam lower flange and the second beam lower flange, and the first beam lower flange and the second beam lower flange are each joined to the lower flange joining plates with high-strength bolts.

[0018] (3) Furthermore, the beam joining structure according to the present invention is a structure in which a pair of second beams, each having an H-shaped cross section and the same beam configuration as the first beam, are joined to a first beam having an H-shaped cross section in a direction perpendicular to the first beam, with the first beam sandwiched between them, an upper flange joint portion in which the second beam upper flange is rigidly joined to the first beam upper flange or in which opposing second beam upper flanges are rigidly joined to each other via a member; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; The lower flange joining plate, whose width gradually increases toward the first beam lower flange side, is arranged on the upper and lower surfaces of the first beam lower flange and the second beam lower flange so as to span the first beam lower flange and the second beam lower flange, and is characterized by having a lower flange joining portion in which the first beam lower flange and the second beam lower flange are each joined to the lower flange joining plate with high-strength bolts.

[0019] (4) Furthermore, the beam joining structure according to the present invention is a structure in which a pair of second beams, each having an H-shaped cross section and smaller than the first beam, are joined to a first beam having an H-shaped cross section in a direction perpendicular to the first beam, with the first beam sandwiched between them, an upper flange joint portion in which upper flange joint plates, the width of which gradually increases toward the first beam upper flange side, are placed on the upper and lower surfaces of the first beam upper flange and the second beam upper flange so as to straddle the first beam upper flange and the second beam upper flange, and the first beam upper flange and the second beam upper flange are respectively joined to the upper flange joint plates with high-strength bolts; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; It is characterized by having a lower flange joint portion rigidly connecting the second beam lower flange to a horizontal plate connected to the first beam web.

[0020] (5) In addition, in the above (4), the lower flange joint portion is The lower flange joining plates, whose width gradually increases toward the horizontal plate side, are placed on the upper and lower surfaces of the horizontal plate and the second beam lower flange so as to straddle the horizontal plate and the second beam lower flange, and the horizontal plate and the second beam lower flange are each joined to the lower flange joining plates by high-strength bolts.

[0021] (6) Furthermore, the beam joining structure according to the present invention is a structure in which a pair of second beams, each having an H-shaped cross section and smaller than the first beam, are joined to a first beam having an H-shaped cross section in a direction perpendicular to the first beam, with the first beam sandwiched between them, an upper flange joint portion in which the second beam upper flange is rigidly joined to the first beam upper flange or in which opposing second beam upper flanges are rigidly joined to each other via a member; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; The structure is characterized by having a horizontal plate joined to the first beam web, a lower flange joining plate whose width gradually increases toward the horizontal plate side, which is placed on the upper and lower surfaces of the horizontal plate and the second beam lower flange so as to straddle the horizontal plate and the second beam lower flange, and a lower flange joining portion in which the horizontal plate and the second beam lower flange are each joined to the lower flange joining plate with high-strength bolts.

[0022] (7) Furthermore, in any of the above (1) to (6), the bolts used in the high-strength bolt joint are arranged in multiple rows in the material axis direction at least in the first beam and are arranged in a staggered pattern.

[0023] (8) In addition, in the above-mentioned (1) to (7), the lower limit of the yield point of the joining plate is 355 N / mm 2 The present invention is characterized by the above. [Effects of the Invention]

[0024] The joining members, such as the joining plate for the upper flange in the present invention, have a shape in which their width gradually increases toward the first beam side as the stress increases, so that the strength of the joining members can be efficiently improved without increasing the plate thickness, and a beam joint with sufficient strength can be achieved. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is an explanatory diagram of a beam joint structure according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along the arrow BB in FIG. [Figure 4] 1. FIG. 4 is an explanatory view (part 1) of another embodiment of the joining plate for the upper flange of FIG. [Figure 5] 1. FIG. 4 is an explanatory view (part 2) of another embodiment of the upper flange joining plate of FIG. [Figure 6] 1. FIG. 4 is an explanatory view (part 3) of another embodiment of the upper flange joining plate of FIG. [Figure 7] 10A and 10B are diagrams illustrating stresses acting on a beam joint structure according to an embodiment. [Figure 8] 10A and 10B are explanatory diagrams of another aspect of the beam joint structure according to the embodiment. [Figure 9] 9 is a cross-sectional view taken along the arrow CC in FIG. 8. [Figure 10]FIG. 10 is a cross-sectional view taken along the arrow DD in FIG. 9. [Figure 11] This is an explanatory diagram of the floor frame structure in a steel-framed building. [Figure 12] 12 is a horizontal view of the continuous beam substructure of FIG. 11, illustrating the stress and bending moment acting on the continuous beam substructure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0026] A beam joint structure 1 according to one embodiment of the present invention shows a joint structure between a first beam and a second beam arranged perpendicular to the first beam, which constitute a floor frame of a steel-framed building. The beam joint structure 1 of this embodiment is applied to, for example, a beam joint A between a main beam 35 and a sub-beam 37 in Fig. 11, in which the first beam corresponds to the main beam 35 and the second beam corresponds to the sub-beam 37.

[0027] 11, the floor frame 31 may also be provided with a grandchild beam 43 that is perpendicular to the sub-beam 37. The grandchild beams 43 may be arranged facing each other across the sub-beam 37, with their ends rigidly joined to the sub-beam 37. The beam joint structure 1 of this embodiment may also be applied to the beam joint B between such a sub-beam 37 and grandchild beam 43, in which case the first beam corresponds to the sub-beam 37 and the second beam corresponds to the grandchild beam 43. First, an example of a beam joint structure 1 in which the first beam and the second beam have the same beam configuration is shown in FIGS. 1 to 3, and will be specifically described below.

[0028] As shown in Figures 1 to 3, the beam joining structure 1 is formed by joining a first beam 3 having an H-shaped cross section to a pair of second beams 5 having the same beam configuration as the first beam 3 and an H-shaped cross section, which are placed on either side of the first beam 3 in a direction perpendicular to the first beam 3. The beam joint structure 1 comprises an upper flange joint 7 where the second beam upper flange 5a is joined to the first beam upper flange 3a with high-strength bolts, a web joint 9 where the second beam web 5b is joined to a vertical plate 13 joined to the first beam 3 with high-strength bolts, and a lower flange joint 11 where the second beam lower flange 5c is joined to the first beam lower flange 3c with high-strength bolts. Each joint will be described in detail below.

[0029] <Upper flange joint> The upper flange joint 7 is formed by high-strength bolt joints (rigid joints) of the second beam upper flange 5a of the second beam 5 (hereinafter simply referred to as the "opposing second beam 5") that faces the first beam 3 across from it to the first beam upper flange 3a of the first beam 3, and is specifically as follows.

[0030] Upper flange joining plates 15a and 15b are attached to the upper and lower surfaces of the first beam upper flange 3a and the second beam upper flange 5a, which are located at the same height, respectively. The first beam upper flange 3a and the second beam upper flange 5a are joined to these upper flange joining plates 15a and 15b with high-strength bolts 17, respectively. As described above, the first beam upper flange 3a and the second beam upper flange 5a are rigidly joined by two-surface friction high-strength bolt joints. As a result, stress acting on one second beam upper flange 5a is transmitted to the other second beam upper flange 5a via the high-strength bolts 17, upper flange joining plates 15a and 15b, and the first beam upper flange 3a.

[0031] The upper flange joining plate 15b, which is arranged on the underside of the first beam upper flange 3a and the second beam upper flange 5a, is divided into four parts to avoid interference with the first beam web 3b, the second beam web 5b, and the vertical plate 13. In this embodiment, the upper flange joining plate 15a arranged on the upper surface of the first beam upper flange 3a and the second beam upper flange 5a also has a four-part divided shape like the upper flange joining plate 15b, but this is not the case because the upper flange joining plate 15a does not interfere with the first beam web 3b, etc. For example, the upper flange joining plate 15a may be divided into two pieces, in which case it may be divided along the axis of the first beam 3 (divided to the left and right of the first beam web 3b) as shown in Figure 4, or it may be divided along the axis of the second beam 5 (divided above and below the second beam web 5b) as shown in Figure 5. As shown in FIG. 6, the upper flange joining plate 15a may be made of one undivided piece.

[0032] Conventionally, joining plates used to join the flanges of the first beam 3 and the second beam 5 with high-strength bolts have generally been rectangular in shape with a width corresponding to the flange width of the second beam 5, such as joining member 41A in Patent Document 1 (see Figure 6B of Patent Document 1). In contrast, the upper flange joining plates 15a, 15b in this embodiment are arranged along the upper flange surfaces of the first beam 3 and the second beam 5, as shown in Figure 1, and each of the four divided pieces has a shape in which the width gradually increases toward the first beam upper flange 3a side.

[0033] The width of the upper flange joining plates 15a, 15b has been gradually increased toward the first beam 3 so that they extend in the width direction of the second beam upper flange 5a, resulting in a larger contact area between the upper flange joining plates 15a, 15b and the first beam upper flange 3a than before. Therefore, more high-strength bolts 17 can be arranged to join the upper flange joining plates 15a, 15b and the first beam upper flange 3a than before, and the bearing strength of the upper flange joining portion 7 can be improved compared to before.

[0034] Furthermore, by adopting such a shape, the cross-sectional area of ​​the upper flange joining plates 15a, 15b gradually increases toward the first beam 3 side, thereby improving the bearing strength of the upper flange joining plates 15a, 15b themselves.

[0035] As described above, by shaping the upper flange joining plates 15a, 15b so that their width gradually increases toward the first beam upper flange 3a side, the strength of the upper flange joining portion 7 can be improved without increasing the plate thickness of the upper flange joining plates 15a, 15b.

[0036] Furthermore, even if the upper flange joining plate 15a is divided into two pieces or consists of a single piece, the same effect as above can be obtained by making it so that its width gradually increases toward the first beam upper flange 3a side.

[0037] In addition, in the upper flange joining plates 15a and 15b in Figure 1, the portion connecting the widest portion and the narrowest portion is formed so that the width gradually increases in a linear manner, but the present invention is not limited to this, and the portion may be formed so that the width gradually increases in a curved manner.

[0038] On the other hand, it is also possible to increase the width of the upper flange joining plates 15a, 15b along their entire length, i.e., to make the upper flange joining plates 15a, 15b rectangular and wider than conventional ones, but the shape of this embodiment has the following advantages.

[0039] 7 is a diagram in which the stress acting on the beam-joint structure 1 of this embodiment is represented by light gray fill. The height of the filled part indicates the magnitude of the stress, and the higher the height, the greater the stress acting on that part. As explained in Figure 12, when a floor load is applied to the floor frame, stress acts on the beam joint, causing a tensile bending moment at the top end. As shown in Figure 7, this stress increases toward the first beam 3, and is greatest at the first beam center (the widthwise center of the first beam, indicated by the dashed line in the figure). Therefore, the stress acting on the upper flange joining plates 15a and 15b also increases toward the first beam 3 side.

[0040] In contrast, the upper flange joining plates 15a, 15b in this embodiment gradually increase in width toward the first beam upper flange 3a side, and therefore their cross-sectional area also gradually increases toward the first beam 3 side, resulting in a shape that is rational against the acting stresses. This shape improves the yield in manufacturing the components and is more economical than when the width is increased along the entire length, and also reduces the weight of the components, making them easier to handle during assembly.Furthermore, the beam joints are also more compact, which is preferable.

[0041] The steel material used for the upper flange joining plates 15a and 15b has a standard lower limit of yield point of 355 N / mm 2 By using a high-strength material to form the upper flange joining plates 15a, 15b, it is possible to further reduce the thickness of the upper flange joining plates 15a, 15b, which is expected to further improve workability and transportation efficiency.

[0042] The specification design for each component of the beam joint structure 1 is based on the magnitude of the stress acting on the beam joint. As mentioned above, the stress acting on the beam joint increases toward the first beam core, so in design, the diameter and number of high-strength bolts 17 are determined based on the maximum value, i.e., the magnitude of the stress expected to act on the first beam core. Here, the stress value used as the design standard (stress value at the first beam core) is called the design stress value. In addition, it is common practice to set the number of high-strength bolts 17 provided on the first beam 3 side to be the same as the number of high-strength bolts 17 provided on the second beam 5 side from the viewpoint of stress transmission (see Figure 1).

[0043] Once the number and arrangement of high-strength bolts 17 are determined, the maximum width of the upper flange connecting plates 15a, 15b is determined so as to enclose the high-strength bolts 17 arranged on the first beam 3 side, and the length of the upper flange connecting plates 15a, 15b is determined so as to enclose the high-strength bolts 17 arranged on the second beam 5 side. The thickness and yield strength of the upper flange joining plates 15a, 15b are determined so that they can withstand the above-mentioned design stress values. The cross-sectional area (width x thickness) of the upper flange joining plates 15a, 15b must be large enough to withstand the design stress values, and in this embodiment, the necessary cross-sectional area is ensured by increasing the plate width. This ensures the necessary strength without making the upper flange joining plates 15a, 15b too thick.

[0044] The high-strength bolts 17 provided on the first beam 3 side are arranged in the material axis direction of the first beam 3, and the high-strength bolts 17 provided on the second beam 5 side are arranged in the material axis direction of the second beam 5, but the row of high-strength bolts 17 can also be arranged in multiple rows depending on the flange width. For example, if the flange width of the first beam 3 is relatively large, the high-strength bolts 17 can be arranged in two rows as shown in Figure 1, so that the maximum width of the upper flange joining plates 15a, 15b does not become excessively large due to the number of high-strength bolts 17, and can be set to the minimum necessary size.

[0045] When arranging the high-strength bolts 17 in multiple rows, the high-strength bolts 17 may be arranged in a grid pattern, or may be arranged in a staggered pattern, like the high-strength bolts 17 on the first beam 3 side in the example of Figure 1. In particular, the staggered arrangement is preferable compared to the grid arrangement because it can be applied to flanges with smaller widths.

[0046] The above describes an example in which the maximum width of the upper flange joining plates 15a, 15b is reduced by arranging multiple rows of high-strength bolts 17 on the first beam 3 side, but if the flange width of the second beam 5a is greater than a certain level, it is also advisable to arrange multiple rows of high-strength bolts 17 on the second beam 5 side. By arranging the high-strength bolts 17 on the second beam 5 side in multiple rows, the length of the upper flange joining plates 15a, 15b can be reduced, making the beam joining portion more compact.

[0047] <Web joint> The web joint 9 is formed by high-strength bolt-joining (rigidly joining) the second beam web 5b of the opposing second beam 5 to a vertical plate 13 joined to the first beam 3, and is specifically as follows.

[0048] A pair of vertical plates 13 are provided on both sides of the first beam web 3b of the first beam 3, and are arranged to form the same plane as the second beam web 5b of the second beam 5. The vertical plates 13 are plate-like members having the same shape as the area surrounded by the first beam upper flange 3a, the first beam web 3b, and the first beam lower flange 3c, and are arranged to close the area and are joined to the first beam upper flange 3a, the first beam web 3b, and the first beam lower flange 3c.

[0049] Web joining plates 19 are attached to both sides of the second beam web 5b and the vertical plate 13, and are arranged to straddle the second beam web 5b and the vertical plate 13, and the second beam web 5b and the vertical plate 13 are each joined to these plates by high-strength bolts 17. As described above, the second beam webs 5b of the opposing second beams 5 are rigidly joined to the vertical plates 13 by two-face friction high-strength bolt joints.

[0050] <Bottom flange joint> The lower flange joint 11 is formed by joining the second beam lower flange 5c of the opposing second beam 5 to the first beam lower flange 3c of the first beam 3 with high-strength bolts (rigid joint), as follows.

[0051] Lower flange joining plates 21a and 21b are attached to the upper and lower surfaces of the first beam bottom flange 3c and the second beam bottom flange 5c, which are located at the same height, respectively, and are arranged to straddle the first beam bottom flange 3c and the second beam bottom flange 5c. These lower flange joining plates 21a and 21b are joined to the first beam bottom flange 3c and the second beam bottom flange 5c, respectively, with high-strength bolts 17. In this way, the first beam bottom flange 3c and the second beam bottom flange 5c are rigidly joined by a two-face friction high-strength bolt joint, so that stress acting on one second beam bottom flange 5c is transmitted to the other second beam bottom flange 5c via the high-strength bolt 17, bottom flange joining plates 21a and 21b, and the first beam bottom flange 3c.

[0052] The lower flange joining plate 21a, which is arranged on the upper surface side of the first beam lower flange 3c and the second beam lower flange 5c, has a shape divided into four pieces, similar to the above-mentioned upper flange joining plate 15b, and each of the divided pieces has a shape that gradually increases in width toward the first beam lower flange 3c side. Further, the lower flange joining plate 21b arranged on the lower surface side of the first beam lower flange 3c and the second beam lower flange 5c also has the same shape as the lower flange joining plate 21a. The lower flange joining plates 21a, 21b are similar to the above-described upper flange joining plates 15b, 15a, and therefore a detailed description thereof will be omitted.

[0053] The lower flange joining plates 21a, 21b are also shaped so that their width gradually increases toward the first beam bottom flange 3c, which increases the contact area between the lower flange joining plates 21a, 21b and the first beam bottom flange 3c compared to conventional straight plates. This allows for more high-strength bolts 17 to be placed between the lower flange joining plates 21a, 21b and the first beam bottom flange 3c than conventional plates, improving the strength of the lower flange joint 11. Furthermore, the cross-sectional area of ​​the lower flange joining plates 21a, 21b is larger than that of the conventional lower flange joining plates, and therefore the bearing strength of the lower flange joining plates 21a, 21b themselves is improved.

[0054] As described above, by shaping the lower flange joining plates 21a, 21b so that their width gradually increases toward the first beam lower flange 3c side, the strength of the lower flange joining portion 11 can be improved without increasing the plate thickness of the lower flange joining plates 21a, 21b.

[0055] In addition, the lower limit of the yield point for the lower flange joining plates 21a and 21b is 355 N / mm 2 It is desirable to use the above high strength materials for the construction, which allows the plate thickness of the lower flange joining plates 21a, 21b to be thin, and is expected to improve workability during assembly.

[0056] As described above, in this embodiment, the bearing strength of the upper flange joint portion 7 can be improved by using the upper flange joint plates 15a, 15b whose width gradually increases toward the first beam upper flange 3a. Furthermore, by using the lower flange joint plates 21a, 21b whose widths gradually increase toward the first beam lower flange 3c, the bearing strength of the lower flange joint portion 11 can be improved. Therefore, by applying the beam joint structure 1 of this embodiment, the strength of beam joint A and beam joint B (see Figure 11) can be improved compared to conventional cases without increasing the plate thickness of the joint plate and without unnecessarily enlarging the planar shape.

[0057] In addition, the upper flange joining plates 15a, 15b and the lower flange joining plates 21a, 21b have a shape that is rational for the stress acting on the beam joining portion, which results in good yield in component manufacturing, transportation efficiency, and workability during assembly.

[0058] In the above example, the first beam upper flange 3a and the second beam upper flange 5a are the same thickness, and the first beam lower flange 3c and the second beam lower flange 5c are the same thickness. However, if the flange thickness of the second beam 5 is smaller than the flange thickness of the first beam 3, it is advisable to use a filler plate. Specifically, as shown in FIG. 6A of Patent Document 1, a filler plate is attached to the underside of the second beam upper flange 5a, and the first beam upper flange 3a and the second beam upper flange 5a are joined with high-strength bolts via the filler plate.

[0059] Furthermore, although Figures 1 to 3 show an example in which the beam thickness of the first beam 3 and the second beam 5 are the same, if the beam thickness of the second beam 5 is smaller than that of the first beam 3, the configuration will be as shown in Figures 8 to 10. Since the upper flange joint 7 and web joint 9 of the beam joint structure 23 shown in Figures 8 to 10 are similar to the examples shown in Figures 1 to 3, the same symbols are used and their explanations are omitted, and only the lower flange joint 25 will be explained below.

[0060] <Bottom flange joint> The lower flange joint 25 is formed by high-strength bolting (rigidly joining) the second beam lower flange 5c of the opposing second beam 5 to a horizontal plate 27 joined to the first beam web 3b, as follows:

[0061] A pair of horizontal plates 27 are provided on both sides of the first beam web 3b of the first beam 3, and are arranged to form the same plane as the second beam lower flange 5c of the second beam 5. In addition, a pair of reinforcing stiffeners 29 parallel to the vertical plates 13 are provided on both sides of the first beam web 3b, sandwiching the horizontal plate 27 and reinforcing the horizontal plate 27 (see Figures 9 and 10).

[0062] The horizontal plate 27 is a plate material formed to the same thickness as the second beam lower flange 5c, and the length in the material axis direction of the first beam 3 is set to be greater than the maximum width of the lower flange joining plates 21a, 21b described later. The horizontal plate 27 has a slit formed therein to avoid interference with the vertical plate 13, and the vertical plate 13 is inserted into this slit. The horizontal plate 27 may be divided at the vertical plate 13. Alternatively, the horizontal plate 27 may not have a slit, and the vertical plate 13 may be divided into upper and lower parts through the horizontal plate 27.

[0063] Lower flange joining plates 21a and 21b are attached to the upper and lower surfaces of horizontal plate 27 and second beam lower flange 5c, which are arranged at the same height, respectively, and are arranged so as to straddle horizontal plate 27 and second beam lower flange 5c. These lower flange joining plates 21a and 21b are joined to horizontal plate 27 and second beam lower flange 5c, respectively, with high-strength bolts 17. The lower flange joining plates 21a, 21b are the same as those explained in FIG. 1 etc., and therefore explanation of the shape etc. will be omitted.

[0064] In this way, the horizontal plate 27 and the second beam bottom flange 5c are rigidly joined by a two-face friction high-strength bolt joint, so that stress acting on one second beam bottom flange 5c is transmitted to the other second beam bottom flange 5c via the high-strength bolts 17, bottom flange joining plates 21a and 21b, horizontal plate 27, and first beam web 3b.

[0065] As described above, when the beam configurations of the first beam 3 and the second beam 5 are different, the second beam lower flange 5c can be joined to the first beam 3 with high-strength bolts by providing horizontal plates 27 on both sides of the first beam web 3b, whose length in the material axis direction of the first beam 3 is greater than the maximum width of the lower flange joining plates 21a, 21b.

[0066] The present invention is characterized by the use of a joining plate whose shape gradually increases in width toward the first beam side to join the flanges of the first beam and the second beam with high-strength bolts. The beam joining structure 1 and beam joining structure 23 described above have the above characteristics in both the upper flange joint 7 and the lower flange joint 11 (25), but the present invention is not limited to this. In other words, the present invention also includes a configuration in which the upper flange joint 7 is constructed by high-strength bolt connection using upper flange joint plates 15a, 15b, and the lower flange joint 11 (25) is constructed by another method. The present invention also includes a configuration in which the upper flange joint 7 is constructed by another method and the lower flange joint 11 (25) is constructed by high-strength bolt connection using lower flange joint plates 21a, 21b.

[0067] When the upper flange joint 7 or the lower flange joint 11 (25) is configured by another method, it is sufficient that the joint is rigidly joined so as to be able to exert rotational rigidity as a joint, and known techniques can be applied. For example, the flanges of the first beam 3 and the second beam 5 may be rigidly joined by welding them together, or the flanges of the opposing second beams 5 may be rigidly joined directly to each other without using the first beam 3. As a method for rigidly joining the flanges of the opposing second beams 5 directly to each other, for example, there is a method in which a long plate-like member is placed across the first beam 3 to the opposing second beam 5, and the flanges of the second beams 5 are joined to the member by fillet welding or bolts. [Explanation of symbols]

[0068] 1 Beam joint structure 3 1st beam 3a First beam upper flange 3b First beam web 3c First beam bottom flange 5 2nd beam 5a Second beam upper flange 5b Second beam web 5c Second beam bottom flange 7 Upper flange joint 9 Web Joint 11 Lower flange joint 13 Vertical Plate 15a, 15b Upper flange joining plate 17 High-strength bolts 19 Web joining plate 21a, 21b Lower flange joining plate 23 Beam joint structure (other aspects) 25 Lower flange joint (other aspects) 27 Horizontal Plate 29 Reinforcement stiffener 31 Floor frame 33 Pillars 35 Large beam 37 Small beam 39 Continuous beam 41 Floor load 43 Sun Liang

Claims

1. A beam joining structure in which a pair of second beams having an H-shaped cross section and the same beam configuration as the first beam are joined to a first beam having an H-shaped cross section in a direction perpendicular to the first beam, sandwiching the first beam therebetween, an upper flange joint portion in which upper flange joint plates, the width of which gradually increases toward the first beam upper flange side, are placed on the upper and lower surfaces of the first beam upper flange and the second beam upper flange so as to straddle the first beam upper flange and the second beam upper flange, and the first beam upper flange and the second beam upper flange are respectively joined to the upper flange joint plates with high-strength bolts; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; A beam joining structure characterized by comprising a lower flange joining portion that rigidly joins a second beam lower flange to a first beam lower flange or rigidly joins opposing second beam lower flanges together via a member.

2. The lower flange joint portion rigidly joins the second beam lower flange to the first beam lower flange, The beam connection structure described in claim 1, characterized in that lower flange connecting plates, whose width gradually increases toward the first beam lower flange side, are placed on the upper and lower surfaces of the first beam lower flange and the second beam lower flange so as to span the first beam lower flange and the second beam lower flange, and the first beam lower flange and the second beam lower flange are each connected to the lower flange connecting plates with high-strength bolts.

3. A beam joining structure in which a pair of second beams having an H-shaped cross section and the same beam configuration as the first beam are joined to a first beam having an H-shaped cross section in a direction perpendicular to the first beam, sandwiching the first beam therebetween, an upper flange joint portion rigidly joining the second beam upper flange to the first beam upper flange or rigidly joining opposing second beam upper flanges to each other via a member; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; A beam joining structure characterized by comprising: a lower flange joining plate whose width gradually increases toward the first beam lower flange side, which is arranged on the upper and lower surfaces of the first beam lower flange and the second beam lower flange so as to span the first beam lower flange and the second beam lower flange, and a lower flange joining portion in which the first beam lower flange and the second beam lower flange are each joined to the lower flange joining plate with high-strength bolts.

4. A beam joining structure in which a pair of second beams, each having an H-shaped cross section and smaller than the first beam, are joined to a first beam having an H-shaped cross section on both sides of the first beam in a direction perpendicular to the first beam, an upper flange joint portion in which upper flange joint plates, the width of which gradually increases toward the first beam upper flange side, are placed on the upper and lower surfaces of the first beam upper flange and the second beam upper flange so as to straddle the first beam upper flange and the second beam upper flange, and the first beam upper flange and the second beam upper flange are respectively joined to the upper flange joint plates with high-strength bolts; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; A beam connection structure characterized by comprising a lower flange connection portion rigidly connecting the second beam lower flange to a horizontal plate connected to the first beam web.

5. The lower flange joint portion is The beam connection structure described in claim 4, characterized in that lower flange connecting plates, whose width gradually increases toward the horizontal plate side, are placed on the upper and lower surfaces of the horizontal plate and the second beam lower flange so as to span the horizontal plate and the second beam lower flange, and the horizontal plate and the second beam lower flange are each connected to the lower flange connecting plates with high-strength bolts.

6. A beam joining structure in which a pair of second beams, each having an H-shaped cross section and smaller than the first beam, are joined to a first beam having an H-shaped cross section on both sides of the first beam in a direction perpendicular to the first beam, an upper flange joint portion rigidly joining the second beam upper flange to the first beam upper flange or rigidly joining opposing second beam upper flanges to each other via a member; a web joint rigidly connecting the second beam web to a vertical plate connected to the first beam; A beam connection structure characterized by having a horizontal plate joined to a first beam web, a lower flange connection plate whose width gradually increases toward the horizontal plate, arranged on the upper and lower surfaces of the horizontal plate and the second beam lower flange so as to span the horizontal plate and the second beam lower flange, and a lower flange connection portion in which the horizontal plate and the second beam lower flange are each connected to the lower flange connection plate with high-strength bolts.

7. A beam joint structure described in any one of claims 1 to 6, characterized in that the bolts used in the high-strength bolt joint are arranged in multiple rows in the material axis direction at least in the first beam and are arranged in a staggered pattern. 【Request Item 8】 The lower limit of the yield point of the joining plate is 355N / mm 2 7. The beam joint structure according to claim 1, wherein the beam joint structure is a beam joint structure having a thickness of 1000 .mu.m.

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