Girder-beam connection structure

Abstract

To provide a girder-beam connection structure capable of reducing size of a joint part between a girder and a beam.SOLUTION: A girder-beam connection structure 1 according to the invention connects a pair of beams 5 to a girder 3 so as to face each other on both sides across the girder 3 in a direction orthogonal to the girder 3. The girder-beam connection structure comprises: a beam upper flange connection part 9 consisting of a standing plate 15 connected to a top face of a beam upper flange 5a of each of the pair of beams 5 so as to stand in a beam axis direction, and two connection plates 21 that face both surfaces of the standing plate 15 and are disposed across the standing plate 15 and connected to the standing plate 15 with high-strength bolts; a beam web connection part 11 that rigidly connects beam webs 5b of the beams 5 facing each other to a girder web 3b; and a beam lower flange connection part 13 that rigidly connects beam lower flanges 5c of the beams 5 facing each other to the girder 3, or rigidly connects the facing beam lower flanges 5c with each other through a member.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a connection structure between a main beam and a secondary beam of a framework in a steel frame structure.

Background Art

[0002] Conventionally, a framework for supporting a concrete floor in a steel frame structure is composed of main beams arranged in parallel at predetermined intervals and secondary beams arranged to connect the main beams. When a vertical load is applied to the central part of the secondary beam, the secondary beam deflects, and cracks occur in the concrete near the joint between the main beam and the secondary beam due to the rotational deformation (angle) generated at the joint. Therefore, a technique for reducing the deflection of the secondary beam is required.

[0003] Therefore, a technique has been proposed in Patent Document 1 to make the secondary beams facing each other across the main beam function as a connecting beam to reduce the deflection of the secondary beam. In Patent Document 1, the upper flanges of the secondary beams facing each other across the main beam are fastened via a splice plate and fastening means arranged across both of them. And, the web engagement member provided on the main beam and the web of the secondary beam are fastened via a splice plate and fastening means arranged across both of them. Further, the lower flanges of the secondary beams are joined by a metal touch via the web and compression member of the main beam.

[0004] In Patent Document 1, by fastening (rigidly joining) the joint between the main beam and the secondary beam, the rotational deformation (angle) generated at the joint between the main beam and the secondary beam is reduced, thereby reducing the deflection of the secondary beam. Note that rigid joining means a strong joining that does not generate rotational deformation (angle).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, in Patent Document 1, the upper flanges of the girders are fastened via a splice plate and fastening means arranged across both of them, so that the stress (tensile force) acting on the upper flange of one girder is transmitted to the other girder. At this time, in order to transmit the stress sufficiently, it is necessary to generate sufficient frictional force between the upper flange of the girder and the splice plate. When the fastening force of the bolts is the same, the larger the contact area, the greater the frictional force. Conventionally, when the cross-section of the girder is large and the flange width and flange plate thickness are large, etc., a long splice plate of about 2 m may be used to ensure the necessary frictional force. Therefore, the joint part has become large and has been a problem.

[0007] The present invention has been made to solve the above problems, and an object thereof is to provide a large beam - small beam joint structure capable of compactifying the joint part of a large beam and a small beam.

Means for Solving the Problems

[0008] (1) The large beam - small beam joint structure according to the present invention joins a pair of small beams with an H-shaped cross-section on both sides of a large beam in a direction orthogonal to the large beam with the large beam sandwiched therebetween, a standing plate joined in a state of standing in the small beam axial direction on the upper surface of each small beam upper flange of the pair of small beams, and two joining plates arranged so as to straddle the standing plate facing both surfaces of the standing plate and joined to the standing plate with high-strength bolts, and a small beam upper flange joint part constituted by the two; a small beam web joint part in which the small beam webs of the opposing small beams are rigidly joined to the large beam respectively; a small beam lower flange joint part in which the lower flanges of the opposing small beams are rigidly joined to the large beam respectively, or the lower flanges of the opposing small beams are rigidly joined to each other via a member, and is characterized by including these.

[0009] (2) The large beam - small beam joint structure according to the present invention is one in which a pair of small beams made of H - shaped steel having the same beam shape as the large beam are opposed to each other and joined on both sides of a large beam made of H - shaped steel, sandwiching the large beam in a direction orthogonal to the large beam, It is composed of a standing plate joined in a state of standing in the small beam axial direction on the upper surface of each small beam upper flange of the pair of small beams, and two joining plates arranged so as to straddle the standing plates facing each other on both sides of the standing plate and joined to the standing plate with high - strength bolts, which constitutes a small beam upper flange joint portion, 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 large beam web respectively, It is characterized by including a small beam lower flange joint portion in which the small beam lower flanges of the opposing small beams are rigidly joined to the large beam lower flange respectively, or the opposing small beam lower flanges are rigidly joined to each other via a member.

[0010] (3) Further, the large beam - small beam joint structure according to the present invention is one in which a pair of small beams made of H - shaped steel having a beam shape smaller than the large beam are opposed to each other and joined on both sides of a large beam made of H - shaped steel, sandwiching the large beam in a direction orthogonal to the large beam, It is composed of a standing plate joined in a state of standing in the small beam axial direction on the upper surface of each small beam upper flange of the pair of small beams, and two joining plates arranged so as to straddle the standing plates facing each other on both sides of the standing plate and joined to the standing plate with high - strength bolts, which constitutes a small beam upper flange joint portion, 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 large beam web respectively, It is characterized by including a small beam lower flange joint portion in which the small beam lower flanges of the opposing small beams are rigidly joined to horizontal plates joined to the large beam web respectively.

[0011] (4) Further, the large beam - small beam joint structure according to the present invention is one in which a pair of small beams made of H - shaped steel are opposed to each other and joined on both sides of a large beam made of H - shaped steel, sandwiching the large beam in a direction orthogonal to the large beam, A standing plate joined in a state of standing in the direction of the truss axis on the upper surface of each truss upper flange of the pair of trusses, and two joining plates arranged so as to straddle the standing plate on both sides of the standing plate and joined to the standing plate with high-strength bolts, and a truss upper flange joining portion composed of; A truss web joint portion in which the opposing truss webs of the opposing trusses are rigidly joined to the vertical plates joined to the girder web by friction joining with a group of high-strength bolts, respectively; The lower flanges of the opposing trusses are characterized in that neither of them is joined.

[0012] (5) Further, in any one of the above (1) to (4), the standing plate and the joining plate have a specified lower limit value of the yield point of 355 N / mm 2 or more.

Effect of the Invention

[0013] In the present invention, the upper flanges of the opposing trusses sandwiching the girder can be joined by a more efficient method than before, so that the frictional force required for joining can be ensured without using large members, and the girder-truss joint portion can be made compact.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0015] The large beam - small beam joint structure 1 according to an embodiment of the present invention shows a joint structure between a large beam constituting a floor frame structure of a building steel frame and a pair of small beams facing each other with the large beam interposed therebetween. Examples where the beam composition of the small beam is smaller than that of the large beam are shown in FIGS. 1 to 3, and will be specifically described below. Note that FIGS. 1(b), 2(b), and 3(b) are end views showing only the cross - sectional end faces of the small beams with the large beam omitted.

[0016] As shown in FIGS. 1 to 3, the large beam - small beam joint structure 1 joins a pair of small beams 5 made of H - shaped steel to both sides of a large beam 3 made of H - shaped steel with the large beam 3 interposed therebetween in a direction orthogonal to the large beam 3. The pair of small beams 5 have the same cross - section, and the beam composition, beam width, and the plate thicknesses of the upper flange 5a of the small beam, the web 5b of the small beam, and the lower flange 5c of the small beam are the same respectively. The large beam - small beam joint structure 1 includes an upper flange joint portion 9 where the upper flanges 5a of the pair of small beams 5 are joined, a web joint portion 11 where the web 5b of the small beam is joined to the large beam 3, and a lower flange joint portion 13 where the lower flange 5c of the small beam is joined to the large beam 3. Hereinafter, each joint portion will be described in detail.

[0017] <Upper flange joint portion of the small beam> As shown in FIG. 1, the small beams 5 facing each other with the large beam 3 interposed therebetween (hereinafter simply referred to as "opposing small beams 5") are arranged at a height position where their respective upper flanges 5a form the same plane as the upper flange 3a of the large beam 3. On the upper surfaces of the upper flange 5a of the opposing webs 5, as shown in Figs. 2(a) and 2(b), two vertical plates 15 each are provided in a state of standing in the web axial direction. A plurality of bolt holes 17 are formed in each vertical plate 15 in the longitudinal direction of the vertical plate 15. The bolt holes 17 are elongated holes that are long in the longitudinal direction of the vertical plate 15 so as to follow the manufacturing errors of the girder 3 and the web 5 and the construction errors at the site. The shape of the bolt holes 17 is not limited to elongated holes, and may be circular with a larger hole diameter than usual, or may be the diameter of a normal high-strength bolt when sufficient construction accuracy can be ensured.

[0018] The two vertical plates 15 provided on one web 5 are arranged so as to form the same plane as the two vertical plates 15 provided on the other web 5 respectively. That is, the first vertical plate 15 of the other web 5 is located on the extension line of the first vertical plate 15 of one web 5, and the second vertical plate 15 of the other web 5 is located on the extension line of the second vertical plate 15 of one web 5. These vertical plates 15 may be welded to the web 5 at the factory in advance.

[0019] The height of the vertical plate 15 is set to be equal to or less than the thickness of the floor slab 19 placed on the girder 3 and the web 5 (see Fig. 3(b)). Note that the number of vertical plates 15 is not limited to two, and may be one or three or more. In any case, the plate thickness, steel strength, height, and number of vertical plates 15 may be set so that the total cross-sectional area of the vertical plates 15 is equal to or greater than the cross-sectional area or load-bearing capacity of the upper flange 5a of the web. Also, the length of the vertical plate 15 may be set according to the required joining force.

[0020] On both sides of each vertical plate 15, two joining plates 21 arranged so as to straddle the opposing vertical plates 15 (the vertical plate 15 of one web 5 and the vertical plate 15 of the other web 5 opposing this) are joined by high-strength bolts 23 (high-strength bolt friction joining). The shape (cross-sectional area) of the joint plate 21 is set in combination with the steel strength so that the yield strength of the joint plate 21 is equal to or greater than the yield strength of the vertical plate 15.

[0021] As described above, the upper flange 5a of the opposing small beams 5 is frictionally joined via the vertical plate 15 and the joint plate 21. As a result, the stress acting on the upper flange 5a of one small beam 5 is transmitted to the upper flange 5a of the other small beam 5, and the rotational deformation (angle) of the upper flange of the small beam is suppressed (restrained).

[0022] Here, the shear strength q of the high-strength bolt friction joint by is represented by the following formula (1). In formula (1), m is the number of friction surfaces, μ is the friction coefficient, and N0 is the tightening force (introduced tension) of the high-strength bolt. q by = m·μ·N0 ···(1) As shown in formula (1), when the friction coefficient of the friction surface and the tightening force of the high-strength bolt are constant, the shear strength of the high-strength bolt friction joint increases as the number of friction surfaces increases.

[0023] On the other hand, in this embodiment, by providing the vertical plate 15 on the upper surface of the upper flange 5a of the small beam, a two-sided shear high-strength bolt friction joint is formed with the joint plate 21 arranged on both sides of the vertical plate 15. Therefore, compared with the conventional example in which the upper flanges 5a of the small beams are joined by a single-sided shear high-strength bolt friction joint, the frictional force can be improved efficiently. As a result, it is not necessary to use a long member as in the conventional case, so that the joint portion 9 of the upper flange of the small beam can be made compact.

[0024] <Small beam web joint portion> On both sides of the web 3b of the main beam 3, a pair of vertical plates 25 are provided so as to form the same plane as the web 5b of the opposing small beams 5. The vertical plate 25 is a plate-shaped member having the same shape as the region surrounded by the upper flange 3a, the web 3b, and the lower flange 3c of the main beam, and is arranged so as to close the region and is joined to the upper flange 3a, the web 3b, and the lower flange 3c of the main beam.

[0025] On both sides of the web 5b of the secondary beam and the vertical plate 25, a gusset plate 27 is arranged so as to straddle both of them, and the gusset plate 27 is fastened to the web 5b of the secondary beam and the gusset plate 27 is fastened to the vertical plate 25 by high-strength bolts 23. As described above, the webs 5b of the opposing secondary beams 5 are rigidly joined (fastened) to the main beam web 3b via the vertical plates 25 and the gusset plates 27, respectively.

[0026] <Lower flange joint of secondary beam> On both sides of the vertical plate 25 of the main beam 3, plate-shaped horizontal plates 29 are provided. The horizontal plates 29 are arranged so as to form the same plane as the lower flange 5c of the secondary beam 5, and are joined to the vertical plate 25 and the main beam web 3b.

[0027] At the boundary between the lower flange 5c of the secondary beam web 5b and the end in the axial direction of the secondary beam, a scallop 31 (notch) is formed, and the lower flange 5c is welded and joined to the horizontal plate 29 by a welded part 33. As described above, the lower flanges 5c of the opposing secondary beams 5 are welded and joined to the horizontal plates 29 of the main beam 3, and thus are rigidly joined to the main beam 3, respectively.

[0028] Fig. 3 shows the state where the floor slab 19 is placed on the frame using the main beam-secondary beam joint structure 1 of the present embodiment. In Fig. 3(a), 35 is a headed stud, 37 and 39 are the upper and lower main reinforcement bars extending in the axial direction of the main beam, and 41 and 43 are the upper and lower force-bearing reinforcement bars extending in the axial direction of the secondary beam. Note that the floor slab reinforcement shown in Fig. 3 is an example, and the present embodiment is of course valid even when the directions of the main reinforcement bars and the force-bearing reinforcement bars in the figure are interchanged or a part of the reinforcement is omitted. As described above, the height of the vertical plate 15 is set to be equal to or less than the thickness of the floor slab 19 so that the vertical plate 15 does not protrude from the floor slab 19. If the height of the vertical plate 15 is set lower than the height of the headed stud 35 as shown in Fig. 3, it is more preferable because the vertical plate 15 does not interfere with the upper main reinforcement bar 37 and the upper force-bearing reinforcement bar 41, and the cover thickness from the top end of the floor slab 19 can be ensured.

[0029] In addition, the steel materials used for the vertical plate 15 and the joint plate 21 are preferably high-strength materials with a specified lower limit value of the yield point of 355 N / mm 2 or higher. By constructing the vertical plate 15 and the joint plate 21 with high-strength materials, it becomes possible to reduce the height (width) of the vertical plate 15 and the joint plate 21, or to reduce the plate thickness, and further compactification of the joint part and improvement of workability can be expected.

[0030] The present invention is characterized by the joining method of the joist upper flange joint, and does not limit the joining methods of the joist web joint 11 and the joist lower flange joint 13. The joist web joint 11 and the joist lower flange joint 13 may be rigidly joined so as to exhibit rotational rigidity as a joint part, and may be joined by, for example, the following methods. Regarding the joist web joint 11, in the above, an example of bolt-joining the joist web 5b and the vertical plate 25 via the gusset plate 27 was shown. However, without using the gusset plate 27, a part of the vertical plate 25 may be projected toward the joist web 5b side and directly bolt-joined to the joist web 5b. Also, regarding the joist lower flange joint 13, in the above, an example of welding and joining the joist lower flange 5c to the horizontal plate 29 was shown, but this may be bolt-joining via a gusset plate.

[0031] In addition, in the above, since the beam depth of the joist 5 is smaller than that of the girder 3, the horizontal plate 29 was used. However, when the beam depths of the girder 3 and the joist 5 are the same, it is not necessary to use the horizontal plate 29, and a configuration in which the joist lower flange 5c and the girder lower flange 3c are welded and joined is adopted. Alternatively, a configuration in which the opposing joist lower flanges are rigidly joined may be adopted. As a method of rigidly joining the opposing joist lower flanges, for example, there is a method of abutting a plate-like member arranged so as to straddle both on the lower surfaces of the opposing joist lower flanges and welding and joining the joist lower flanges to the member.

[0032] According to the present embodiment configured as described above, since the upper flange 5a of the opposing small beams 5 are joined by high-strength bolt friction joint with double-sided shear, the frictional force of the upper flange joint portion 9 of the small beam is improved compared to the conventional case. Therefore, it is not necessary to make the joining plate 21 long as in the conventional case, the number of high-strength bolts can be reduced, and the joint portion can be made compact. Also, in the conventional example, since the joining plate and the upper flange 5a of the small beam are directly bolted together, it was necessary to provide bolt holes (cross-sectional defects) in the upper flange 5a of the small beam. However, in the present embodiment, since no bolt holes are provided in the upper flange 5a of the small beam, the ultimate strength is higher than that of the conventional example.

[0033] Also, in the upper flange joint portion 9 of the small beam, by increasing the friction coefficient of the high-strength bolt friction joint portion, the number of high-strength bolts 23 can be reduced. As a method for increasing the friction coefficient of the high-strength bolt friction joint portion, there are methods such as performing rust treatment or blasting treatment on the friction surfaces of the vertical plate 15 and the joining plate 21, or applying an inorganic zinc-rich paint. In addition, there are also methods such as inserting an aluminum plate or aluminum foil between the vertical plate 15 and the joining plate 21, or performing aluminum spraying.

[0034] Also, as another aspect, as shown in FIG. 4, by making the joining force of the small beam web joint portion 11 stronger, it is also possible to adopt a configuration in which the lower flange 5c of the small beam is not joined to either. When sufficient joining force (constraint effect of rotational deformation (angle)) can be expected for the small beam web joint portion 11 by friction joining using a large gusset plate 27 and a large number of high-strength bolts (high-strength bolt group) as in the large beam - small beam joining structure 45 of FIG. 4, the joining of the lower flange 5c of the small beam may be omitted. Furthermore, as shown in FIG. 5, in the small beam web joint portion 11, the number of high-strength bolts on the side of the lower flange 5c of the small beam may be further increased to improve the transmission performance of the bending moment.

[0035] The above is an example in which the joist 5 is tightly connected (rigidly joined) to the girder 3 without joining the lower flange 5c of the joist to either, by constructing the web joint 11 of the joist more strongly. However, it is also possible to configure the web joint 11 of the joist in the same manner as in FIG. 1, and without joining the lower flange 5c of the joist to either, and to design it to allow rotational deformation (angle) of the joist 5. This can be said to be a semi-rigid joint of the joist 5 to the girder 3. Also in this case, since the upper flange joint 9 of the joist and the web joint 11 of the joist resist rotational deformation of the joist 5 to some extent, deflection of the joist 5 can be reduced.

[0036] As described above, since the girder-joist joint structure 45 in FIGS. 4 and 5 is configured not to weld the lower flange 5c of the joist, there is no need to provide a scallop 31 on the web 5b of the joist, and further labor saving and cost reduction can be expected.

[0037] In the above description, the girder 3 and the joist 5 using H-shaped steel are taken as examples. However, for example, the girder 3 may be a steel box girder or an RC girder. Also, the joist 5 may have an H-shaped cross section or may be made of other materials as long as it has an H-shaped cross section. As an example, the present invention can also be applied to a girder 3 having a box-shaped cross section and a joist 5 having an H-shaped cross section. Also in this case, the upper flange joint 9 of the joist, which is a feature of the present invention, can be configured in the same manner as in FIG. 1 etc. Also, the web joint 11 and the lower flange joint 13 of the joist can be formed by rigidly joining the web 5b and the lower flange 5c of the joist to the girder 3 respectively. Note that the lower flanges 5c of the joists facing each other via a member may be rigidly joined.

Explanation of reference numerals

[0038] 1 Girder-joist joint structure 3 Girder 3a Upper flange of girder 3b Web of girder 3c Lower flange of girder 5 Joist 5a Upper flange of joist 5b Web of joist 5c Lower flange of joist 9 Upper flange joint of the crossbeam 11 Web joint of the crossbeam 13 Lower flange joint of the crossbeam 15 Vertical plate 17 Bolt hole 19 Floor slab 21 Joint plate 23 High-strength bolt 25 Vertical plate 27 Gusset plate 29 Horizontal plate 31 Scallop 33 Weld joint 35 Stud with head 37 Upper main reinforcement 39 Lower main reinforcement 41 Upper distribution reinforcement 43 Lower distribution reinforcement 45 Girder-crossbeam joint structure (other aspect)

Claims

1. A pair of small beams with an H-shaped cross-section are opposed to each other and joined on both sides of a large beam across the large beam in a direction orthogonal to the large beam, a vertical plate joined in a state of standing in the small beam axial direction on the upper surface of each small beam upper flange of the pair of small beams, and two joining plates arranged so as to straddle the vertical plates facing both sides of the vertical plate and joined to the vertical plate with high-strength bolts, which constitute a small beam upper flange joining portion, a small beam web joining portion in which the small beam webs of the opposed small beams are rigidly joined to the large beam respectively, a large beam - small beam joining structure characterized by comprising a small beam lower flange joining portion in which the small beam lower flanges of the opposed small beams are rigidly joined to the large beam respectively, or the small beam lower flanges of the opposed small beams are rigidly joined to each other via a member.

2. A large beam - small beam joining structure in which a pair of small beams made of H-shaped steel having the same beam configuration as the large beam are opposed to each other and joined on both sides of a large beam made of H-shaped steel across the large beam in a direction orthogonal to the large beam, a vertical plate joined in a state of standing in the small beam axial direction on the upper surface of each small beam upper flange of the pair of small beams, and two joining plates arranged so as to straddle the vertical plates facing both sides of the vertical plate and joined to the vertical plate with high-strength bolts, which constitute a small beam upper flange joining portion, a small beam web joining portion in which the small beam webs of the opposed small beams are rigidly joined to vertical plates joined to the large beam web respectively, a large beam - small beam joining structure characterized by comprising a small beam lower flange joining portion in which the small beam lower flanges of the opposed small beams are rigidly joined to the large beam lower flange respectively, or the small beam lower flanges of the opposed small beams are rigidly joined to each other via a member.

3. A large beam - small beam joining structure in which a pair of small beams made of H-shaped steel having a beam configuration smaller than the large beam are opposed to each other and joined on both sides of a large beam made of H-shaped steel across the large beam in a direction orthogonal to the large beam, a vertical plate joined in a state of standing in the small beam axial direction on the upper surface of each small beam upper flange of the pair of small beams, and two joining plates arranged so as to straddle the vertical plates facing both sides of the vertical plate and joined to the vertical plate with high-strength bolts, which constitute a small beam upper flange joining portion, a small beam web joining portion in which the small beam webs of the opposed small beams are rigidly joined to vertical plates joined to the large beam web respectively, a large beam - small beam joining structure characterized by comprising a small beam lower flange joining portion in which the small beam lower flanges of the opposed small beams are rigidly joined to horizontal plates joined to the large beam web respectively.

4. A girder-small beam joint structure in which a pair of small beams made of H-shaped steel are opposed and joined on both sides of a girder made of H-shaped steel with the girder interposed therebetween in a direction orthogonal to the girder, a vertical plate joined in a state of standing in the small beam axial direction on the upper surface of each of the small beam upper flanges of the pair of small beams, and two joining plates arranged so as to straddle the vertical plates facing both surfaces of the vertical plate and joined to the vertical plate with high-strength bolts, and a small beam upper flange joint portion constituted by the two joining plates, a small beam web joint portion in which the small beam webs of the opposing small beams are rigidly joined to the vertical plates joined to the girder web by friction joining with a group of high-strength bolts, respectively, wherein the lower flanges of the opposing small beams are not joined to each other. A girder-small beam joint structure characterized by this.

5. The vertical plate and the joint plate have a specified lower limit value of the yield point of 355 N / mm 2 or more, and the girder and joist joint structure according to any one of claims 1 to 4, characterized in that.

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