Girder-beam connection structure

Abstract

To provide a girder-beam connection structure enabling high-strength bolt friction joint between a lower flange of a beam and a girder with sufficient joining strength.SOLUTION: A girder-beam connection structure 1 according to the invention comprises: a beam upper flange connection part 7 at which beam upper flanges 5a are rigidly connected to a girder upper flange 3a, or the beam upper flanges 5a are rigidly connected to each other; a beam web connection part 9 at which a beam web 5b is rigidly connected to a vertical plate 19 connected to a girder web 3b; and a beam lower flange connection part 11 at which beam lower flanges 5c are connected to a pair of lower flange side horizontal plates 23, respectively, that are connected to a girder lower flange 3c and disposed across the beam lower flange 5c in a width direction. The beam lower flange connection part 11 is formed by connecting the beam lower flange 5c and the lower flange side horizontal plate 23 with high-strength bolts 17 to two connection plates 25 disposed on upper faces and lower faces of the beam lower flange 5c and the lower flange side horizontal plate 23 so as to straddle them.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a girder-to-beam joint structure in a steel frame structure. [Background technology]

[0002] Conventionally, the framework supporting the concrete floor of a steel-framed building consists of main girders arranged parallel to each other at a specified interval, and sub-girders arranged to connect the main girders. When a vertical load is applied to the center of the sub-girders, the sub-girders deflect, and the rotational deformation (corner) that occurs at the joint between the main girder and the sub-girder causes cracks in the concrete near the joint. Therefore, technology to reduce the deflection of the sub-girders is needed.

[0003] Therefore, Patent Document 1 discloses a technology in which two sub-beams arranged in a butt-jointed state on both sides of a main girder are connected to each other via a slab placed across the upper flange of the main girder and the upper flange of the sub-beam, thereby forming the two sub-beams into a continuous beam. According to the technique of Patent Document 1, two sub-beams can be configured as a continuous beam without joining the upper flange of the sub-beam to the upper flange of the main beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-068001 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, as mentioned above, the upper flanges of the sub-beams are connected to each other without using the upper flanges of the main beams, while the lower flanges of the sub-beams are joined to the connecting flanges of the joint members fixed to both sides of the webs of the main beams. The connecting flange and the lower flange of the sub-beam are positioned at the same height as each other, and the butt joint is sandwiched between two splice plates, and the splice plate and the lower flange of the sub-beam, and the splice plate and the connecting flange are fastened together with multiple bolts.

[0006] In Patent Document 1, the bottom flanges of the sub-beams and the connecting flanges are joined by double shear high-strength bolt friction joints, whereby the bottom flanges of the opposing sub-beams are joined to each other via the connecting flanges. Since the stress acting on the lower flange of one sub-beam is transmitted to the lower flange of the other sub-beam via the connecting flange, the high-strength bolt friction joint must be constructed with enough strength to resist this transmitted stress.

[0007] In order to increase the joint strength of high-strength bolt friction joints, it is advisable to extend the length of the splice plate to increase the friction area and to add bolts to the connecting flange side and the sub-beam side. However, in the configuration of Patent Document 1, the group of connecting bolts on the main girder side must be placed in a very narrow area approximately half the width of the main girder flange x the width of the secondary girder flange, making it difficult to increase the number of bolts, and there was a risk that the connecting strength would be insufficient when large stresses were applied.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a girder-sub-beam connection structure that can frictionally connect the lower flange of the sub-beam to the main girder using high-strength bolts with sufficient connection strength. [Means for solving the problem]

[0009] (1) The girder-sub-beam joint structure according to the present invention is a structure in which a pair of sub-beams, each made of H-shaped steel and having the same beam diameter as the girder, are joined to a girder made of H-shaped steel on both sides of the girder in a direction perpendicular to the girder, A girder upper flange joint portion in which the upper flange of the opposing secondary girders is rigidly joined to the girder upper flange respectively, or the upper flanges of the opposing secondary girders are rigidly joined to each other via a member, and A secondary girder web joint portion in which the webs of the opposing secondary girders are rigidly joined to the vertical plates joined to the girder web respectively, and A secondary girder lower flange joint portion in which the lower flanges of the opposing secondary girders are joined to a pair of lower flange side horizontal plates joined to the girder lower flange and arranged so as to sandwich the secondary girder lower flange in the width direction, respectively, and the secondary girder lower flange joint portion is characterized in that the secondary girder lower flange and the lower flange side horizontal plates are joined to two joining plates arranged on the upper and lower surfaces so as to straddle the secondary girder lower flange and the lower flange side horizontal plates with high strength bolts respectively.

[0010] (2) Further, the girder-secondary girder joint structure according to the present invention is a structure in which a pair of secondary girders made of H-shaped steels smaller than the girder are opposed to each other and joined to a girder made of an H-shaped steel with the girder sandwiched therebetween in a direction orthogonal to the girder, and A girder upper flange joint portion in which the upper flange of the opposing secondary girders is rigidly joined to the girder upper flange respectively, or the upper flanges of the opposing secondary girders are rigidly joined to each other via a member, and A secondary girder web joint portion in which the webs of the opposing secondary girders are rigidly joined to the vertical plates joined to the girder web respectively, and A secondary girder lower flange joint portion in which the lower flanges of the opposing secondary girders are joined to a pair of lower flange side horizontal plates joined to the girder web and arranged so as to sandwich the secondary girder lower flange in the width direction, respectively, and the secondary girder lower flange joint portion is characterized in that the secondary girder lower flange and the lower flange side horizontal plates are joined to two joining plates arranged on the upper and lower surfaces so as to straddle the secondary girder lower flange and the lower flange side horizontal plates with high strength bolts respectively.

[0011] (3) In addition, in the above-mentioned (1) or (2), the sub-beam upper flange joints are each joined to a pair of upper flange-side horizontal plates that are joined to the upper flange of the main beam and are arranged to sandwich the sub-beam upper flange in the width direction. The sub-beam upper flange joint is characterized in that the sub-beam upper flange and the upper flange side horizontal plate are each joined with high-strength bolts to two joining plates arranged on the upper and lower surfaces of the sub-beam upper flange and the upper flange side horizontal plate so as to straddle them.

[0012] (4) The girder-sub-beam joint structure according to the present invention is a structure in which a pair of sub-beams, each made of an H-shaped steel, are joined to a girder made of an H-shaped steel in a direction perpendicular to the girder, sandwiching the girder between them, and the sub-beams are joined to each other, a sub-beam upper flange joint in which the sub-beam upper flanges of the opposing sub-beams are joined to a pair of upper flange-side horizontal plates that are joined to the main beam upper flange and arranged to sandwich the sub-beam upper flange in the width direction; a sub-beam web joint in which the sub-beam webs of opposing sub-beams are rigidly connected to vertical plates connected to the main beam web; and a sub-beam bottom flange joint portion rigidly joining the sub-beam bottom flanges of the opposing sub-beams to the main girder, or rigidly joining the opposing sub-beam bottom flanges to each other via a member; The sub-beam upper flange joint is characterized in that the sub-beam upper flange and the upper flange side horizontal plate are each joined with high-strength bolts to two joining plates arranged on the upper and lower surfaces of the sub-beam upper flange and the upper flange side horizontal plate so as to straddle them.

[0013] (5) In addition, in the above-mentioned (1) to (4), 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]

[0014] In this invention, the lower flange of the sub-beam is friction-connected to a pair of lower flange-side horizontal plates arranged on either side of the sub-beam in the width direction with high-strength bolts, which makes it easy to increase the friction area of the joint and add more bolts. Therefore, even when the stress acting on the sub-beam is large, the joint strength required for stress transmission can be ensured. [Brief explanation of the drawings]

[0015]

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[0016] A girder-to-beam joint structure 1 according to one embodiment of the present invention shows a joint structure between a girder that constitutes a floor frame of a steel-framed building and a pair of sub-beams that face each other across the girder. An example in which the sub-beam and the girder have the same beam structure is shown in Figures 1 to 3, and will be described in detail below. Note that Figure 3 is an end view that shows only the cross-sectional end surface of the sub-beam, with the girder omitted.

[0017] As shown in Figures 1 to 3, the girder-to-beam joint structure 1 is constructed by joining a girder 3 made of H-shaped steel to a pair of sub-beams 5 made of H-shaped steel, facing each other on either side of the girder 3 in a direction perpendicular to the girder 3. The girder-to-beam joint structure 1 comprises a sub-beam upper flange joint 7 that joins the sub-beam upper flanges 5a of the pair of sub-beams 5, a sub-beam web joint 9 that joins the sub-beam web 5b to the girder 3, and a sub-beam lower flange joint 11 that joins the sub-beam lower flange 5c to the girder 3. Each joint will be described in detail below.

[0018] <Sub-beam upper flange joint> As shown in Figure 1, the sub-beams 5 (hereinafter simply referred to as "opposing sub-beams 5") that face each other across the main beam 3 are positioned at a height position such that the upper flanges 5a of each sub-beam form the same plane as the upper flanges 3a of the main beam 3. Two standing plates 13 are provided on the upper surfaces of the beam upper flanges 5a of the opposing beams 5, and are joined in an upright state in the beam axial direction (see FIG. 3). These standing plates 13 are preferably welded to the joists 5 in advance at the factory.

[0019] On both sides of each standing plate 13, two joining plates 15 are arranged so as to straddle the opposing standing plates 13 (the standing plate 13 of one sub-beam 5 and the standing plate 13 of the other sub-beam 5 opposite it), and are joined by high-strength bolts 17 (high-strength bolt friction joint).

[0020] As described above, the upper flange 5a of the opposing girders 5 are rigidly joined via the vertical plate 13 and the joining plate 15. As a result, the stress acting on the upper flange 5a of one girder 5 is transmitted to the upper flange 5a of the other girder 5. Note that the rigid joining means a strong joining that does not cause rotational deformation (angle).

[0021] <Girder web joint> On both sides of the girder web 3b of the main girder 3, a pair of vertical plates 19 are provided so as to form the same plane as the opposing girder webs 5b of the girders 5. The vertical plate 19 is a plate-like member having the same shape as the region surrounded by the upper flange 3a of the main girder, the girder web 3b, and the lower flange 3c of the main girder, and is arranged so as to close the region and is joined to the upper flange 3a of the main girder, the girder web 3b, and the lower flange 3c of the main girder.

[0022] On both sides of the girder web 5b and the vertical plate 19, gusset plates 21 are arranged so as to straddle both of them, and the gusset plates 21 and the girder web 5b, and the gusset plates 21 and the vertical plate 19 are respectively fastened by high-strength bolts 17. As described above, the opposing girder webs 5b of the girders 5 are rigidly joined to the girder web 3b via the vertical plate 19 and the gusset plate 21 respectively.

[0023] <Lower flange joint of girder> On both side edges of the lower flange 3c of the main girder 3, as shown in FIG. 2, a pair of lower flange side horizontal plates 23 (shown in dark gray) are joined so as to sandwich the lower flange 5c of the girder in the width direction. It is preferable to weld these lower flange side horizontal plates 23 to the lower flange 3c of the main girder in the factory in advance.

[0024] The lower flange side horizontal plate 23 shall have the same thickness and the same strength material as the lower flange 5c of the girder. Further, the width of the lower flange side horizontal plate 23 may be 1 / 2 or more of the width of the lower flange 5c of the girder, but it is desirable that the width be sufficient to ensure the strength of the welded portion with the lower flange 3c of the main girder. In addition, in order to cope with errors during construction, a clearance of about 10 mm may be set between the outer edges of the lower flange side horizontal plate 23 and the lower flange of the small beam 5c.

[0025] Both side edges of the lower flange of the small beam 5c are frictionally joined to the adjacent lower flange side horizontal plate 23 by high-strength bolts. Specifically, two joining plates 25 (shown in light gray) are arranged on the upper and lower surfaces respectively so as to straddle the lower flange of the small beam 5c and the lower flange side horizontal plate 23, and the lower flange of the small beam 5c and the lower flange side horizontal plate 23 are joined to the joining plate 25 by high-strength bolts 17 respectively.

[0026] Thus, the stress (compressive force) acting on one lower flange of the small beam 5c is transmitted to the opposite lower flange of the small beam 5c through the high-strength bolt 17, the joining plate 25, the lower flange side horizontal plate 23, and the lower flange of the large beam 3c. Based on the cross-sectional area and yield strength of the lower flange of the small beam 5c, the diameter and arrangement (number) of the high-strength bolt 17 and the specifications (yield strength, plate thickness, length, etc.) of the joining plate 25 are designed so as to withstand this stress transmission.

[0027] In the above-described conventional example, since the lower flange of the small beam 5c and the lower flange side horizontal plate 23 were butted against each other in the longitudinal direction of the small beam 5 and frictionally joined by high-strength bolts, there was a limit to the number of high-strength bolts 17 that could be arranged, and there was a possibility that a sufficient joining force to withstand stress transmission could not be realized. In this regard, in the present embodiment, since the lower flange side horizontal plate 23 is arranged so as to sandwich the lower flange of the small beam 5c in the width direction, it is easy to add high-strength bolts 17.

[0028] For example, the lower flange side horizontal plate 23 and the joining plate 25 may be extended in the axial direction of the small beam to add high-strength bolts 17 to improve the joining force. Also, when the width of the lower flange of the small beam 5c is large, the lower flange side horizontal plate 23 and the joining plate 25 may be enlarged in the width direction of the small beam, and two or more rows of high-strength bolts 17 may be arranged on the small beam side and the lower flange side horizontal plate 23 side respectively.

[0029] Note that since the stress acting on one of the lower flange plates 5c of the crossbeam is transmitted to the other lower flange plate 5c of the crossbeam via the lower flange plate 3c of the main beam, if the yield strength of the lower flange plate 3c of the main beam is lower than that of the lower flange plate 5c of the crossbeam, it is conceivable that the lower flange plate 3c of the main beam cannot withstand the transmitted stress. In this regard, in the present embodiment, by increasing the width of the horizontal plate 23 on the lower flange side, the stress transmitted to the lower flange plate 3c of the main beam can be dispersed, and the risk of damage to the lower flange plate 3c can be reduced. When the width of the horizontal plate 23 on the lower flange side increases, the welded portion with the lower flange plate 3c of the main beam becomes larger, so the stress is transmitted to a wider range of the lower flange plate 3c of the main beam. Therefore, the stress acting on the lower flange plate 3c of the main beam is dispersed, and the lower flange plate 3c of the main beam is less likely to be damaged. As described above, even when the yield strength of the lower flange plate 3c of the main beam is lower than that of the lower flange plate 5c of the crossbeam, by increasing the width of the horizontal plate 23 on the lower flange side, the risk of damage to the lower flange plate 3c of the main beam can be reduced.

[0030] Note that the steel material used for the joint plate 25 preferably has a minimum specified yield point of 355 N / mm 2 or more high-strength material. By configuring the joint plate 25 with a high-strength material, it becomes possible to reduce the plate thickness of the joint plate 25, and it is expected to make the joint part more compact and improve workability.

[0031] As described above, in the present embodiment, the horizontal plate 23 on the lower flange side is arranged so as to sandwich the lower flange plate 5c of the crossbeam in the width direction, and the lower flange plate 5c of the crossbeam is frictionally joined to the horizontal plate 23 on the lower flange side with high-strength bolts. Therefore, it is possible to increase the frictional area and add bolts, and resist a larger stress than before.

[0032] In the above explanation, an example was shown in which the beam diameter of the main girder 3 and the sub-girder 5 are the same, but when the beam diameter of the sub-girder 5 is smaller than that of the main girder 3, the configuration will be as shown in Figures 4 to 6. The sub-girder upper flange joint 7 and the sub-girder web joint 9 of the main girder-sub-girder joint structure 27 shown in Figures 4 to 6 are the same as those in the examples of Figures 1 to 3, so they will be given the same reference numerals and their explanation will be omitted, and only the sub-girder lower flange joint 11 will be explained below.

[0033] In this example, the lower flange-side horizontal plate 23 is formed in an L-shape, as shown in Fig. 5. This L-shaped lower flange-side horizontal plate 23 is positioned at the same height as the sub-beam lower flange 5c, and is joined in pairs to both sides of the girder web 3b. The pair of lower flange-side horizontal plates 23 are positioned facing each other with the L-shape reversed, and the sub-beam lower flange 5c is positioned between them. The portions of the pair of lower flange side horizontal plates 23 that protrude from the main girder 3 sandwich the sub-beam lower flange 5c in the width direction, and these portions and both side edges of the sub-beam lower flange 5c are friction-joined with high-strength bolts. Specifically, the sub-beam lower flange 5c and the lower flange side horizontal plate 23 are each joined with high-strength bolts 17 to two joining plates 25 that are arranged on the upper and lower surfaces of the above-mentioned portions of the lower flange side horizontal plate 23 and the sub-beam lower flange 5c so as to straddle them.

[0034] The shape of the lower flange side horizontal plate 23 can be rectangular in top view as in the example of Figure 2, but by making it L-shaped as in this example, the lower flange side horizontal plate 23 can also be joined to the vertical plate 19. This reinforces the lower flange side horizontal plate 23 and distributes the stress acting on the girder 3. In this example, reinforcing stiffeners 29 arranged parallel to the vertical plate 19 are provided on both sides of the girder web 3b (see Figures 5 and 6). The lower flange side horizontal plate 23 is further reinforced by sandwiching and fixing it between the reinforcing stiffeners 29 and the vertical plate 19.

[0035] Also in this example, the stress (compressive force) acting on one of the lower flange 5c of the crossbeam is transmitted to the other lower flange 5c of the crossbeam on the opposite side through the high-strength bolt 17, the joint plate 25, the lower flange side horizontal plate 23, and the main beam web 3b.

[0036] In addition, the configuration of the lower flange joint 11 of the crossbeam described above can also be applied to the upper flange joint 7 of the crossbeam. Such a mode is shown in FIGS. 7 to 9. Since the web joint 9 and the lower flange joint 11 of the main beam - crossbeam joint structure 31 shown in FIGS. 7 to 9 are the same as those in the examples of FIGS. 1 to 3, the same reference numerals are given and the description is omitted, and only the upper flange joint 7 will be described below.

[0037] In this example, as shown in FIG. 8, on both side edges of the upper flange 3a of the main beam 3, a pair of upper flange side horizontal plates 33 (shown in dark gray) are joined so as to sandwich the upper flange 5a of the crossbeam in the width direction. These upper flange side horizontal plates 33 may be welded to the upper flange 3a of the main beam in the factory in advance, similar to the lower flange side horizontal plate 23.

[0038] The width, thickness, and yield strength of the upper flange side horizontal plate 33 may be set according to the width, thickness, and yield strength of the upper flange 5a of the crossbeam, similar to the lower flange side horizontal plate 23. The same also applies to the clearance provided between the outer edges of the upper flange side horizontal plate 33 and the upper flange 5a of the crossbeam.

[0039] Both side edges of the upper flange 5a of the crossbeam are friction - joined to the adjacent upper flange side horizontal plates 33 by high - strength bolts. Specifically, two joint plates 25 (shown in light gray) are arranged on the upper and lower surfaces respectively so as to straddle the upper flange 5a of the crossbeam and the upper flange side horizontal plate 33, and the joint plate 25, the upper flange 5a of the crossbeam, and the upper flange side horizontal plate 33 are joined by high - strength bolts 17 respectively.

[0040] As a result, the stress (tensile force) acting on one of the upper flange 5a of the cross member is transmitted to the other upper flange 5a of the cross member facing it through the high-strength bolt 17, the joint plate 25, the horizontal plate 33 on the upper flange side, and the upper flange 3a of the main beam. Based on the cross-sectional area and yield strength of the upper flange 5a of the cross member, it is advisable to design the diameter and arrangement (number) of the high-strength bolt 17, and the specifications (yield strength, plate thickness, length, etc.) of the joint plate 25 so as to withstand this stress transmission.

[0041] Figures 7 to 9 show examples where the beam structures of the main beam 3 and the cross member 5 are the same. However, when the beam structure of the cross member 5 is smaller than that of the main beam 3, the modes shown in Figures 10 and 11 are obtained. The upper flange joint portion 7 of the main beam - cross member joint structure 35 shown in Figures 10 and 11 has the same configuration as that in Figure 8, and the lower flange joint portion 11 of the cross member has the same configuration as that in Figure 5.

[0042] Also, as shown in the main beam - cross member joint structure 37 of Figure 12, the upper flange joint portion 7 can be configured as in Figure 8, and the lower flange joint portion 11 can be configured differently. Note that the lower flange joint portion 11 of Figure 12 is an example in which the axial end portion of the lower flange 5c of the cross member is butted against the side surface of the lower flange 3c of the main beam and completely fusion-welded.

[0043] Also, in the upper flange joint portion 7 of Figures 7, 10, and 12, since it is easy to add high-strength bolts 17 according to the stress borne by the upper flange 5a of the cross member, it is possible to sufficiently ensure the joining force required for stress transmission.

[0044] As described above, the present invention is characterized by the configuration of the lower flange joint portion 11 of the cross member described in Figures 2 and 5 and the upper flange joint portion 7 of the cross member described in Figure 8, and those provided with this configuration in either or both of the lower flange joint portion 11 and the upper flange joint portion 7 of the cross member are included in the present invention. Regarding the joint portion to which the above configuration is not applied, it suffices to be rigidly joined so as to exhibit the rotational rigidity as a joint portion, and it may be joined by a method different from those exemplified in Figures 1 to 12.

[0045] For example, in the case of the sub-beam upper flange joint 7, Figure 1 shows an example in which the sub-beam upper flanges 5a are joined together via the vertical plate 13 and the joint plate 15, but the sub-beam upper flange 5a may also be welded to the main girder upper flange 3a. In addition, in the case of the sub-beam web joint 9, Figure 1 shows an example in which the beam web 5b and the vertical plate 19 are bolted together via a splice plate 21, but it is also possible to extend the vertical plate 19 toward the sub-beam web 5b without using the splice plate 21 and bolt it directly to the sub-beam web 5b. In addition, in the case of the sub-beam lower flange joint 11, Figure 12 shows an example in which the sub-beam lower flange 5c is welded to the main beam lower flange 3c, but it is also possible to span a plate-shaped member across the main beam 3 in the axial direction of the sub-beam material and join the sub-beam lower flange 5c to the member by fillet welding. [Explanation of symbols]

[0046] 1 Large beam / small beam joint structure 3 girder 3a Upper flange of main beam 3b Beam web 3c Lower flange of girder 5 Small beam 5a Upper flange of sub-beam 5b Beam web 5c Beam bottom flange 7. Beam upper flange joint 9 Beam web joint 11 Beam bottom flange joint 13 Standing Plate 15 Joint plate 17 High-strength bolts 19 Vertical Plate 21 Plate 23 Lower flange side horizontal plate 25 Joint Plate 27 Beam-beam joint structure (other embodiment 1) 29 Reinforcement stiffener 31 Beam-beam joint structure (other embodiment 2) 33 Upper flange side horizontal plate 35 Beam-beam joint structure (other embodiment 3) 37 Girder - Small beam joint structure (Another aspect 4)

Claims

1. A girder - small beam joint structure in which a pair of small beams made of H - shaped steel having the same beam shape as the girder are opposed to each other with the girder made of H - shaped steel in between, in a direction orthogonal to the girder, and joined together, a small - beam upper - flange joint portion in which the small - beam upper flanges of the opposing small beams are rigidly joined to the girder upper flange respectively, or the opposing small - beam upper flanges are rigidly joined to each other via a member, a small - beam web joint portion in which the small - beam webs of the opposing small beams are rigidly joined to vertical plates joined to the girder web respectively, and a small - beam lower - flange joint portion in which the small - beam lower flanges of the opposing small beams are joined to a pair of lower - flange - side horizontal plates joined to the girder lower flange and arranged with the small - beam lower flanges sandwiched in the width direction, wherein the small - beam lower - flange joint portion is formed by joining the small - beam lower flange and the lower - flange - side horizontal plates to two joining plates arranged on the upper and lower surfaces respectively so as to straddle the small - beam lower flange and the lower - flange - side horizontal plates, with high - strength bolts respectively. The girder - small beam joint structure is characterized by this.

2. A girder - small beam joint structure in which a pair of small beams made of H - shaped steel having a beam shape smaller than the girder are opposed to each other with the girder made of H - shaped steel in between, in a direction orthogonal to the girder, and joined together, a small - beam upper - flange joint portion in which the small - beam upper flanges of the opposing small beams are rigidly joined to the girder upper flange respectively, or the opposing small - beam upper flanges are rigidly joined to each other via a member, a small - beam web joint portion in which the small - beam webs of the opposing small beams are rigidly joined to vertical plates joined to the girder web respectively, and a small - beam lower - flange joint portion in which the small - beam lower flanges of the opposing small beams are joined to a pair of lower - flange - side horizontal plates joined to the girder web and arranged with the small - beam lower flanges sandwiched in the width direction, wherein the small - beam lower - flange joint portion is formed by joining the small - beam lower flange and the lower - flange - side horizontal plates to two joining plates arranged on the upper and lower surfaces respectively so as to straddle the small - beam lower flange and the lower - flange - side horizontal plates, with high - strength bolts respectively. The girder - small beam joint structure is characterized by this.

3. The small - beam upper - flange joint portion is one in which the small - beam upper flanges of the opposing small beams are joined to a pair of upper - flange - side horizontal plates joined to the girder upper flange and arranged with the small - beam upper flanges sandwiched in the width direction The upper flange joint of the joist is characterized in that the upper flange of the joist and the upper flange side horizontal plate are respectively joined to two joint plates arranged on the upper and lower surfaces so as to straddle the upper flange of the joist and the upper flange side horizontal plate by high-strength bolts. The girder-joist joint structure according to claim 1 or 2.

4. A girder-joist joint structure in which a pair of joists using H-shaped steel are opposed to each other with a girder using H-shaped steel interposed therebetween in a direction orthogonal to the girder, An upper flange joint of the joist in which the upper flange of the opposing joists is joined to the upper flange of the girder and is respectively joined to a pair of upper flange side horizontal plates arranged with the upper flange of the joist sandwiched in the width direction, A web joint of the joist in which the webs of the opposing joists are rigidly joined to vertical plates joined to the web of the girder, respectively, It has a lower flange joint of the joist in which the lower flanges of the opposing joists are rigidly joined to the girder respectively, or the lower flanges of the opposing joists are rigidly joined to each other via a member. The upper flange joint of the joist is characterized in that the upper flange of the joist and the upper flange side horizontal plate are respectively joined to two joint plates arranged on the upper and lower surfaces so as to straddle the upper flange of the joist and the upper flange side horizontal plate by high-strength bolts. The girder-joist joint structure.

5. The joining plate has a specified lower limit value of the yield point of 355 N / mm 2 The girder and joist joining structure according to claim 1, 2 or 4, characterized in that it is 355 N / mm or more.

6. The joint plate has a specified lower limit value of yield point of 355 N / mm 2 The girder and joist joint structure according to claim 3, characterized in that it is 355 N / mm or more.

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