Main beam-small beam joint 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 beam - joist connection structure of a framework in a steel - framed structure.

Background Art

[0002] Conventionally, a framework for supporting a concrete floor in a steel - framed structure is composed of large beams arranged in parallel at a predetermined interval and small beams arranged to connect the large beams. When a vertical load is applied to the central part of the small beam, the small beam deflects, and due to the rotational deformation (angle) occurring at the joint between the large beam and the small beam, cracking of the concrete occurs near the joint between the large beam and the small beam. Therefore, a technique for reducing the deflection of the small beam is required.

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

[0004] In Patent Document 1, by fastening (rigidly joining) the joint between the large beam and the small beam, the rotational deformation (angle) occurring at the joint between the large beam and the small beam is reduced, thereby reducing the deflection of the small beam. Note that rigid joining means a strong joining that does not produce 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 mentioned above, in Patent Document 1, the upper flanges of the joists are fastened together via a splice plate and fastening means that spans both of them, thereby transmitting stress (tensile force) acting on the upper flange of one joist to the other joist. In this case, in order to adequately transmit stress, it is necessary to generate sufficient frictional force between the upper flange of the beam and the splice plate. Assuming the same bolt fastening force, the frictional force increases with a larger contact area. Therefore, conventionally, when the beam cross-section was large and the flange width and thickness were large, it was sometimes necessary to use a splice plate about 2 meters long to ensure the required frictional force. This resulted in a large and problematic joint.

[0007] This invention was made to solve the above-mentioned problems, and aims to provide a main beam-secondary beam joint structure that can make the joint between the main beam and secondary beam more compact. [Means for solving the problem]

[0008] (1) The main beam-secondary beam joint structure according to the present invention is a joint in which a main beam is joined to a main beam with a pair of H-shaped secondary beams facing each other on both sides of the main beam in a direction perpendicular to the main beam, The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The webs of opposing beams are rigidly connected to the main beams at the beam web joints, The invention is characterized by having a joint portion where the lower flanges of opposing secondary beams are rigidly connected to the main beam, or where the lower flanges of opposing secondary beams are rigidly connected to each other via a member.

[0009] (2) The main beam-secondary beam joint structure according to the present invention is a main beam made of H-shaped steel, to which a pair of secondary beams made of H-shaped steel with the same beam depth as the main beam are joined opposite each other on both sides of the main beam in a direction perpendicular to the main beam, The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The beam webs of opposing beams are rigidly connected to vertical plates attached to the main beam webs, forming a beam web joint. The invention is characterized by comprising a joint portion of a secondary beam where the lower flanges of opposing secondary beams are rigidly connected to the lower flange of a main beam, or where the lower flanges of opposing secondary beams are rigidly connected to each other via a member.

[0010] (3) Furthermore, the main beam-secondary beam joint structure according to the present invention is a main beam made of H-shaped steel, to which a pair of secondary beams made of H-shaped steel with a smaller beam depth than the main beam are joined to the main beam in a direction perpendicular to the main beam, The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The beam webs of opposing beams are rigidly connected to vertical plates attached to the main beam webs, forming a beam web joint. The invention is characterized by having a joint section where the lower flanges of opposing secondary beams are rigidly connected to a horizontal plate joined to the web of the main beam.

[0011] (4) Furthermore, the main beam-secondary beam joint structure according to the present invention is a main beam made of H-shaped steel, to which a pair of secondary beams made of H-shaped steel are placed opposite each other on both sides of the main beam in a direction perpendicular to the main beam, The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The structure includes a beam web joint where the webs of opposing beams are rigidly connected to a vertical plate joined to the main beam web by frictional connection using groups of high-strength bolts, A key feature is that the lower flanges of the opposing beams are not joined to each other.

[0012] (5) In addition, in any of the items described in (1) to (4) above, the vertical plate and the joint plate have a specified lower limit of yield strength of 355 N / mm 2 The above is the characteristic feature. [Effects of the Invention]

[0013] In this invention, the upper flanges of opposing secondary beams that are flanked by a main beam can be joined in a more efficient manner than in conventional methods. This allows for securing the necessary frictional force for joining without using large components, and enables a more compact main beam-secondary beam joint. [Brief explanation of the drawing]

[0014] [Figure 1] This is an explanatory diagram of a main beam-secondary beam joint structure according to an embodiment. Figure 1(a) is a front view of the web of the secondary beam, and Figure 1(b) is a view of the AA end face of the secondary beam in Figure 1(a) as seen by arrow AA. [Figure 2] Figure 1 is a diagram in which the connecting plate is omitted and the vertical plate is made visible. Figure 2(a) is a front view of the web of the beam, and Figure 2(b) is a view of the BB end face of the beam in Figure 2(a) as indicated by the arrow. [Figure 3] Figure 1 shows the state after the floor concrete slab has been poured onto the upper surfaces of the main beam and secondary beam. Figure 3(a) is a front view of the web of the secondary beam, and Figure 3(b) is a view of the CC end face of the secondary beam in Figure 3(a) as seen by the arrow. [Figure 4]Explanatory drawing of another aspect of the girder - joist joint structure according to the embodiment (Part 1). [Figure 5] Explanatory drawing of another aspect of the girder - joist joint structure according to the embodiment (Part 2).

Mode for Carrying Out the Invention

[0015] The girder - joist joint structure 1 according to an embodiment of the present invention shows a joint structure between a girder constituting a floor framing structure of a building steel frame and a pair of joists facing each other with the girder interposed therebetween. Examples of the case where the beam formation of the joist is smaller than that of the girder 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 joists with the girder omitted.

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

[0017] <Upper joist flange joint portion> As shown in FIG. 1, the joists 5 facing each other with the girder 3 interposed therebetween (hereinafter simply referred to as "opposing joists 5") are arranged at a height position where their respective upper joist flanges 5a form the same plane as the upper girder flange 3a of the girder 3. As shown in Figures 2(a) and 2(b), two vertical plates 15 are provided on the upper surface of the upper flange 5a of the opposing secondary beams 5, joined in an upright position in the direction of the secondary beam axis. Multiple bolt holes 17 are formed in the longitudinal direction of each vertical plate 15. The bolt holes 17 are elongated in the longitudinal direction of the vertical plate 15 to accommodate manufacturing errors and on-site construction errors of the main beam 3 and secondary beams 5. The shape of the bolt holes 17 is not limited to elongated holes; they may be circular with a larger-than-usual diameter, or they may be the normal high-strength bolt hole diameter if sufficient construction accuracy can be ensured.

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

[0019] The height of the vertical plate 15 is set to be less than or equal to the thickness of the floor slab 19 that is poured on top of the main beam 3 and secondary beam 5 (see Figure 3(b)). The number of vertical plates 15 is not limited to two; it may be one or three or more. In any case, the plate thickness or steel strength, height, and number of vertical plates 15 should 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 secondary beam. The length of the vertical plates 15 should be set according to the required joining force.

[0020] On both sides of each vertical plate 15, two connecting plates 21 are positioned to straddle the opposing vertical plates 15 (the vertical plate 15 of one beam 5 and the vertical plate 15 of the other beam 5 opposite to it), and these are joined by high-strength bolts 23 (high-strength bolt friction joint). The shape (cross-sectional area) of the connecting plate 21 is set in conjunction with the steel strength so that the load-bearing capacity of the connecting plate 21 is equal to or greater than that of the vertical plate 15.

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

[0022] Here, the sliding resistance q of the high-strength bolt friction joint by This is expressed by the following equation (1). In equation (1), m is the number of friction surfaces, μ is the coefficient of friction, and N0 is the tightening force (introduction tension) of the high-strength bolt. q by =m·μ·N0···(1) As shown in equation (1), when the coefficient of friction of the friction surfaces and the tightening force of the high-strength bolts are constant, the greater the number of friction surfaces, the greater the sliding resistance of the high-strength bolt friction joint.

[0023] In contrast, in this embodiment, a vertical plate 15 is provided on the upper surface of the upper flange 5a of the beam, and a high-strength bolt friction joint with two-sided shear is made by arranging connecting plates 21 on both sides of the vertical plate 15. Therefore, the friction force can be improved more efficiently compared to the conventional example in which the upper flanges 5a of the beams were joined together with a high-strength bolt friction joint with one-sided shear. As a result, it is no longer necessary to use long members as in the conventional example, and the beam upper flange joint 9 can be made more compact.

[0024] <Beam web joint> A pair of vertical plates 25 are provided on both sides of the main beam web 3b of the main beam 3, arranged to form a coplane with the web 5b of the opposing secondary beam 5. The vertical plates 25 are plate-shaped members with the same shape as the area enclosed by the upper flange 3a, web 3b, and lower flange 3c of the main beam, and are positioned to cover this area and joined to the upper flange 3a, web 3b, and lower flange 3c of the main beam.

[0025] On both sides of the beam web 5b and the vertical plate 25, splice plates 27 are positioned so as to straddle both, and the splice plates 27 and the beam web 5b, and the splice plates 27 and the vertical plate 25 are fastened together with high-strength bolts 23. As described above, the beam webs 5b of opposing beams 5 are rigidly connected (tightly fastened) to the main beam web 3b via the vertical plate 25 and the splice plates 27, respectively.

[0026] <Joint at the lower flange of the joist> Plate-shaped horizontal plates 29 are provided on both sides of the vertical plate 25 of the main beam 3. The horizontal plates 29 are positioned to form a plane with the lower flange 5c of the secondary beam 5 and are joined to the vertical plate 25 and the main beam web 3b.

[0027] A scallop 31 (notch) is formed at the boundary between the beam web 5b and the beam lower flange 5c at the beam axial end, and the beam lower flange 5c is welded to the horizontal plate 29 by a weld 33. As described above, the beam lower flanges 5c of opposing beams 5 are rigidly connected to the main beam 3 by welding to the horizontal plate 29 of the main beam 3.

[0028] Figure 3 shows the state in which a floor slab 19 has been cast into the frame using the main beam / secondary beam joint structure 1 of this embodiment. In Figure 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 distribution reinforcement bars extending in the axial direction of the secondary beam. Note that the floor slab reinforcement shown in Figure 3 is just one example, and this embodiment will of course still be valid even if the direction of the main reinforcement bars and the direction of the distribution reinforcement bars are reversed or if some of the reinforcement is omitted. As mentioned above, the height of the vertical plate 15 is set to be less than or equal to the thickness of the floor slab 19 so that the vertical plate 15 does not protrude from the floor slab 19. Furthermore, as shown in Figure 3, it is preferable to set the height of the vertical plate 15 lower than the height of the headed stud 35 so that the vertical plate 15 does not interfere with the upper main reinforcement 37 and the upper distribution reinforcement 41, and the cover thickness from the top of the floor slab 19 can be ensured.

[0029] The steel used for the vertical plate 15 and the connecting plate 21 has a specified lower limit of yield strength of, for example, 355 N / mm². 2 It is desirable to use the above-mentioned high-strength material. By constructing the vertical plate 15 and the connecting plate 21 from a high-strength material, it becomes possible to reduce the height (width) of the vertical plate 15 and the connecting plate 21, or to reduce the thickness of the plate, which can be expected to further compact the joint and improve workability.

[0030] The present invention is characterized by a method for joining the upper flange joint of a joist, and does not limit the joining method 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 only need to be rigidly joined so as to be able to exhibit rotational rigidity as a joint, and may be joined by, for example, the method described below. Regarding the beam web joint 11, the above example shows a bolted connection between the beam web 5b and the vertical plate 25 via a splice plate 27. However, instead of using the splice plate 27, a portion of the vertical plate 25 may be extended towards the beam web 5b and bolted directly to the beam web 5b. Furthermore, regarding the lower flange joint 13 of the beam, although the above example shows the lower flange 5c of the beam being welded to the horizontal plate 29, this may also be done by bolting it via a splice plate.

[0031] Furthermore, in the above example, a horizontal plate 29 was used because the beam depth of the secondary beam 5 was smaller than that of the main beam 3. However, if the beam depths of the main beam 3 and the secondary beam 5 are the same, there is no need to use the horizontal plate 29, and the lower flange 5c of the secondary beam and the lower flange 3c of the main beam are welded together. Alternatively, the lower flanges of opposing secondary beams may be rigidly joined together. One method for rigidly joining the lower flanges of secondary beams is to place a plate-shaped member that spans both of the lower flanges of opposing secondary beams in contact with their undersides, and then weld the lower flanges of the secondary beams to this member.

[0032] According to this embodiment configured as described above, the upper flanges 5a of opposing beams 5 are joined by a high-strength bolt friction joint with two-sided shear, thus improving the frictional force of the beam upper flange joint 9 compared to conventional designs. Therefore, there is no need to make the joining plate 21 as long as in conventional designs, the number of high-strength bolts can be reduced, and the joint can be made more compact. Furthermore, in conventional examples, the joining plate and the upper flange 5a of the beam are directly bolted together, requiring bolt holes (cross-sectional defects) to be provided in the upper flange 5a of the beam. However, in this embodiment, bolt holes are not provided in the upper flange 5a of the beam, resulting in a higher ultimate load-bearing capacity than in conventional examples.

[0033] Furthermore, in the upper flange joint 9 of the beam, the number of high-strength bolts 23 can be reduced by increasing the coefficient of friction of the high-strength bolt friction joint. Methods for increasing the coefficient of friction of the high-strength bolt friction joint include applying red rust treatment or blast treatment to the friction surfaces of the vertical plate 15 and the joint plate 21, or applying inorganic zinc-rich paint. Other methods include inserting an aluminum plate or aluminum foil between the vertical plate 15 and the joint plate 21, or applying aluminum thermal spraying.

[0034] Furthermore, as shown in Figure 4, another configuration is possible in which the lower flange 5c of the beam is not joined to any of the beams by making the joining force of the beam web joint 11 stronger. In cases where sufficient joining force (restraint effect of rotational deformation (angle)) can be expected at the beam web joint 11 by friction joining using a large splice plate 27 and a large number of high-strength bolts (group of high-strength bolts), as in the main beam-beam joint structure 45 in Figure 4, the joining of the lower flange 5c of the beam may be omitted. Furthermore, as shown in Figure 5, the number of high-strength bolts on the lower flange 5c side of the beam web joint 11 may be further increased to improve the bending moment transmission performance.

[0035] The above is an example in which the beam 5 is rigidly connected to the main beam 3 without connecting the lower flange 5c of the beam to any of the joints, by making the beam web joint 11 more robust. However, the beam web joint 11 may also be configured in the same way as in Figure 1, and the lower flange 5c of the beam may not be connected to any of the joints, allowing rotational deformation (angular deformation) of the beam 5. This can be described as semi-rigid connection of the beam 5 to the main beam 3, but even in this case, the upper flange joint 9 and the beam web joint 11 of the beam resist the rotational deformation of the beam 5 to some extent, so the deflection of the beam 5 can be reduced.

[0036] As described above, the main beam-secondary beam joint structure 45 in Figures 4 and 5 does not involve welding the lower flange 5c of the secondary beam, thus eliminating the need to provide a scallop 31 on the secondary beam web 5b, which can be expected to further reduce labor and costs.

[0037] In the above explanation, we used H-shaped steel for the main beam 3 and secondary beam 5 as examples, but for example, the main beam 3 could be a steel box beam or an RC beam. Also, the secondary beam 5 only needs to have an H-shaped cross-section and may be made of other materials. As an example, the present invention can also be applied to a main beam 3 having a box-shaped cross-section and a secondary beam 5 having an H-shaped cross-section. In this case as well, the secondary beam upper flange joint 9, which is a feature of the present invention, can be configured in the same manner as shown in Figure 1. Furthermore, the beam web joint 11 and the beam lower flange joint 13 can be constructed by rigidly connecting the beam web 5b and the beam lower flange 5c to the main beam 3, respectively. Alternatively, opposing beam lower flanges 5c may be rigidly connected via a connecting member. [Explanation of symbols]

[0038] 1 Large beam / small beam joint structure 3 girder 3a Upper flange of main beam 3b Main beam web 3c Main beam lower flange 5 Small beam 5a Upper flange of secondary beam 5b Small beam web 5c Lower flange of joist 9. Upper flange joint of a secondary beam 11. Beam web joint 13. Lower flange joint of a secondary beam 15 Vertical Plate 17 bolt holes 19 Floor slab 21 Joining plate 23 High-strength bolts 25 Vertical Plate 27 Plate 29 Horizontal Plate 31 Scallop 33 Welded section 35 headed studs 37 Top main bar 39 Bottom main bar 41 Top distribution bar 43 Lower end distribution bar 45. Main beam / secondary beam connection structure (other forms)

Claims

1. A main beam is joined to a main beam, with a pair of H-shaped cross-section beams facing each other on either side of the main beam, in a direction perpendicular to the main beam. The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The webs of opposing beams are rigidly connected to the main beams at the beam web joints, A main beam-beam joint structure characterized by comprising a main beam-beam lower flange joint, in which the lower flanges of opposing main beams are rigidly connected to the main beam, or the lower flanges of opposing main beams are rigidly connected to each other via a member.

2. A main beam made of H-shaped steel is joined to a main beam, with a pair of secondary beams made of H-shaped steel with the same beam depth as the main beam, positioned opposite each other on either side of the main beam in a direction perpendicular to the main beam, wherein The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The beam webs of opposing beams are rigidly connected to vertical plates attached to the main beam webs, forming a beam web joint. A main beam-beam joint structure characterized by comprising a main beam-beam joint portion in which the lower flanges of opposing main beams are rigidly connected to the lower flange of the main beam, or the lower flanges of opposing main beams are rigidly connected to each other via a member.

3. A main beam made of H-shaped steel is joined to a main beam, with a pair of secondary beams made of H-shaped steel having a smaller beam depth than the main beam, positioned opposite each other on either side of the main beam in a direction perpendicular to the main beam, The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The beam webs of opposing beams are rigidly connected to vertical plates attached to the main beam webs, forming a beam web joint. A main beam-beam joint structure characterized by comprising a main beam lower flange joint, in which the lower flanges of opposing main beams are rigidly connected to horizontal plates joined to the main beam web.

4. A main beam made of H-shaped steel is joined to a main beam, with a pair of secondary beams made of H-shaped steel positioned opposite each other on either side of the main beam in a direction perpendicular to the main beam, The beam upper flange joint is composed of a vertical plate joined to the upper surface of the upper flange of each of the pair of beams in an upright position in the direction of the beam axis, and two connecting plates arranged on both sides of the vertical plate so as to straddle the opposing vertical plate and joined to the vertical plate with high-strength bolts, The structure includes a beam web joint where the webs of opposing beams are rigidly connected to a vertical plate joined to the main beam web by frictional connection using groups of high-strength bolts, A main beam-beam connection structure characterized by the fact that the lower flanges of opposing secondary beams are not joined to either of them.

5. The aforementioned vertical plate and the aforementioned joint plate have a specified lower limit yield strength of 355 N / mm². 2 The main beam / secondary beam joint structure according to any one of claims 1 to 4, characterized in that it is as described above.