Steel beam to steel column joint structure and H-shaped steel used for this

Abstract

To provide a joint structure between a steel beam and a steel column that can improve workability on site while securing deformation capacity of the steel beam, and H-beams for this structure.SOLUTION: In a joint structure between a steel beam having an H-shaped cross section consisting of an upper flange, a lower flange and a web, and a steel column, the steel column is provided with an upper diaphragm and a lower diaphragm at the height where the upper and lower flanges of the steel beam are attached, respectively. In the steel beams, an end of the steel beam to be joined to the steel column is not provided with the lower flange, a joining plate is provided on the side of the lower diaphragm so that it protrudes axially from the side of the steel column toward the lower flange of the steel beam, the upper flange of the steel beam is welded to the side of the steel column or to the upper diaphragm, and the lower flange of the steel beam is friction-bonded by high-strength bolt to the joining plate, while no joint is made between the web of the steel beam and the joining plate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a joint structure between a steel beam having an H-shaped cross section consisting of an upper flange, a lower flange, and a web, and a steel column, and to an H-shaped steel used therein. [Background technology]

[0002] The joint structures between steel beams and steel columns in steel frame structures are broadly divided into two types: bracket type and non-bracket type.

[0003] Figures 12(a) to 12(d) show an example of a bracket-type joint structure between a steel beam and a steel column. Figures 12(a) to 12(c) are side views of a steel column 9A, a steel beam 8A, and a joint structure between a steel beam and a steel column, respectively, and Figure 12(d) is a cross-sectional view along line DD in Figure 12(c).

[0004] As shown in Fig. 12(a), in the case of the bracket method, a steel column 9A fabricated with an upper diaphragm 91, a lower diaphragm 92, and a bracket 93 that becomes the end of the steel beam is carried to a construction site. Then, as shown in Fig. 12(c) and Fig. 12(d), at the construction site, the steel beam 8A and the steel column 9A are joined by joining the middle part of the steel beam 8A shown in Fig. 12(b) to the bracket 93 attached to the side of the steel column 9A at a position away from the side of the steel column 9A.

[0005] In this way, in the bracket-type joint structure between a steel beam and a steel column, the upper flange 81, the lower flange 82, and the web 83 of the middle part of the steel beam 8A are friction-joined to the bracket 93 provided on the side of the steel column 9A by the bolt 4 via the splice plates 31, 32, and 35 at the construction site, so that on-site welding is not required and the workability at the site is excellent. However, since it is necessary to provide several brackets 93, which are the ends of the steel beam 8A, on the side of the steel column 9A, the handling of the steel column 9A during transportation is poor. In addition, when the steel column 9A or the steel beam 8A is a member with a large cross section, the weight of the steel members constituting the steel column 9A becomes very large, and transportation is likely to be difficult. Therefore, in order to reduce the weight of the steel members, it becomes necessary to shorten the member length of the steel members constituting the steel column 9A. There is also a problem that the number of welding points increases during the production of the steel column 9A at the steel factory.

[0006] Fig. 13(a) to Fig. 13(d) show an example of a joint structure between a steel beam and a steel column using a non-bracket method. Fig. 13(a) to Fig. 13(c) are a side view of a steel column 9B, a side view of a steel beam 8B, and a side view of the joint structure between a steel beam and a steel column, respectively, and Fig. 13(d) is a cross-sectional view along line DD in Fig. 13(c).

[0007] As shown in FIG. 13(a), in the case of the non-bracket type, a steel column manufactured with an upper diaphragm 91, a lower diaphragm 92, and a gusset plate 94 installed in advance is carried into a construction site. Then, as shown in FIG. 13(c) and FIG. 13(d), at the construction site, the upper flange 81 and the lower flange 82 of the steel beam 8B shown in FIG. 13(b) are welded to the side of the steel column 9B at positions to the sides of the upper diaphragm 91 and the lower diaphragm 92. Alternatively, in the case of a through diaphragm type, the upper flange 81 and the lower flange 82 of the steel beam 8B are welded to the edge of the diaphragm protruding from the side of the steel column 9B. Also, the web 83 of the steel beam 8B shown in FIG. 13(b) is overlapped on the gusset plate 94 installed on the side of the steel column 9B, and joined by the bolt 4. In this manner, the steel beam 8B and the steel column 9B are joined. In addition, as described later, there are cases where, when manufacturing the steel column 9B, no gusset plate 94 is provided on the side of the steel column 9B, and the web 83 at the end of the steel beam 8B is directly welded to the side of the steel column 9B at the construction site.

[0008] In this way, in the joint structure between the steel beam and the steel column using the non-bracket method, the number of accessory parts that are attached to the steel column 9B in advance is small, so the steel column 9A is easy to handle when transporting. In addition, the weight of the steel members that make up the steel column 9B is not likely to increase, making transportation difficult. Therefore, the length of the steel members that make up the steel column 9B can be made longer than in the case of the bracket method.

[0009] For this reason, low- to mid-rise buildings with a small number of components and small cross sections often use bracket-type steel beam-to-column joints, while high-rise buildings with a large number of components and large cross sections often use non-bracket-type steel beam-to-column joints.

[0010] In the case of the non-bracket system which is often used in high-rise buildings, as described above, it is necessary to weld the upper flange 81 and the lower flange 82 of the end of the steel beam 8B to the side of the steel column 9B or to the edges of the upper diaphragm 91 and the lower diaphragm 92 provided on the steel column 9B at the construction site. If the steel column 9B is not provided with a gusset plate 94, it is also necessary to weld the web 83 of the end of the steel beam 8B to the side of the steel column 9B. As described above, since a lot of on-site welding is required, workability at the site is poor.

[0011] Furthermore, when a horizontal force acts on a structure during an earthquake, a bending moment acts on the steel beam 8B, and this bending moment becomes larger the closer to the end of the steel beam 8B. Thus, the end of the steel beam 8B is at high risk of being broken due to the large bending moment acting on it during an earthquake, etc., but the welding of the upper flange 81 and the lower flange 82 of the end of the steel beam 8B is carried out at a construction site, where the working environment is less well-established than in a steel factory. As a result, welding defects are likely to occur in the welded portion of the end of the steel beam 8B, and there is a risk that the deformation capacity of the steel beam 8B will not be sufficiently secured.

[0012] On-site welding of the ends of this steel beam 8B is performed as follows. First, a groove is prepared for welding on the top flange 81 and the bottom flange 82 at the ends of the steel beam 8B. Since upward welding at a construction site is extremely difficult, a square groove is prepared on the top flange 81 and the bottom flange 82 at the ends of the steel beam 8B, as shown in Fig. 13(c), to enable downward welding, and a backing metal 6 is provided below the groove.

[0013] Here, when the upper flange 81 of the end of the steel beam 8B is downward welded to the side of the steel column 9B, there is no obstacle above the upper flange 81 of the end of the steel beam 8B, so the entire width of the upper flange 81 can be welded at once. In contrast, when the lower flange 82 of the end of the steel beam 8B is downward welded to the side of the steel column 9B, the web 83 of the steel beam 8B and the gusset plate 94 provided on the steel column 9B are located above the center of the width of the lower flange 82, and these become obstacles. Therefore, it becomes necessary to weld the lower flange 82 in half in the width direction, and the ends of the welds on both sides overlap at the center of the width of the lower flange 82. Since welding defects are likely to occur at the ends of these welds, welding defects are likely to occur near the center of the width of the lower flange 82 where the ends of the welds on both sides overlap.

[0014] Furthermore, a floor slab (not shown) is often attached on top of the steel beam 8B. Because the floor slab attached on top of the steel beam 8B bears the compressive force, the welded portion of the top flange 81 at the end of the steel beam 8B is less likely to break. In contrast, the tensile force applied to the bottom flange 82 becomes larger, making the welded portion of the bottom flange 82 more likely to break. Therefore, the quality of the welding of the bottom flange 82 has a large effect on the deformation capacity of the steel beam 8B, and therefore advanced technology is required for on-site welding of the bottom flange 82 in particular.

[0015] In addition, in order to ensure the workability of on-site welding in an unprepared working environment, as shown in FIG. 13(c), scallops 831 and 832 are provided on the web 83 at the end of the steel beam 8B so as to expose the welded parts of the upper flange 81 and the lower flange 82, respectively. Among these, the scallop 832 provided on the web 83 near the lower flange 82 becomes the starting point of fracture during an earthquake, which causes a decrease in the deformation capacity of the steel beam 8B. Therefore, in order to reduce the stress generated near the welded part of the lower flange 82 at the end of the steel beam 8B and the scallop 832 to suppress fracture and ensure the deformation capacity of the steel beam 8B, the upper flange 81 and the lower flange 82 at the end of the steel beam 8B are also widened. However, in this case, the amount of welding in the on-site welding increases by the amount of the widening of the width of the upper flange 81 and the lower flange 82 at the end of the steel beam 8B, which further reduces the workability at the site.

[0016] Here, the construction industry is facing a labor shortage problem due to the declining birthrate and aging population, and a shortage of welders at construction sites is becoming an issue. In the construction of high-rise buildings that use the non-bracket method, the ends of the steel beams 8B are welded on-site, so how to secure welders with advanced skills is a major issue.

[0017] In response to such problems, for example, Patent Document 1 proposes a structure in which a bracket consisting of a web and a flange located at its lower edge is welded to the side of a steel column in advance, and then at the construction site, the bottom flange of the steel beam is welded to the flange of the bracket attached to the side of the steel beam, thereby moving the position of the on-site welding away from the side of the steel column and preventing premature fracture of the welded part of the lower flange.

[0018] Furthermore, Patent Document 2 proposes a structure in which a bracket is welded to the side of a steel column in advance, and then at the construction site, the bottom flange of the steel beam is placed on the top surface of the bracket attached to the side of the steel beam and bolted together, thereby joining the bottom flange of the steel beam without performing on-site welding, which is prone to brittle fracture.

[0019] Furthermore, Patent Document 3 proposes a structure in which a diaphragm is installed in a steel column and a through diaphragm type is used, and the upper and lower flanges of a steel beam are bolted to the upper and lower through diaphragms via splice plates. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] Japanese Patent Application Publication No. 9-195384 [Patent Document 2] JP 2000-199271 A [Patent Document 3] JP 2009-249990 A Summary of the Invention [Problem to be solved by the invention]

[0021] However, in the structure described in Patent Document 1, on-site welding of the bottom flange of the steel beam still occurs, so on-site workability has not necessarily improved.

[0022] In addition, in the structure described in Patent Document 2, the bolt joint between the bracket attached to the side of the steel beam and the bottom flange of the steel beam has only one joint surface, so the number of bolts required for friction joint is large, and therefore the protrusion amount of the bracket attached to the steel column needs to be large, which results in an increase in the weight of the steel members that make up the steel column and an increase in the space required for transportation and storage.

[0023] Furthermore, in the structure described in Patent Document 3, it is necessary to perform processing such as suppressing the width of the web at the end of the steel beam so that the end of the steel beam does not interfere with the upper through diaphragm and the lower through diaphragm protruding from the side of the steel column. In addition, in order to frictionally join between the upper through diaphragm and the upper flange of the steel beam, and between the lower through diaphragm and the lower flange of the steel beam, it is necessary to accurately align the height direction positions of the upper and lower through diaphragms and the upper and lower flanges of the steel beam. The dimensions of the steel members change due to the influence of heat input during welding when the members are manufactured, and it is required to manage extremely high dimensional accuracy taking into account thermal deformation due to heat input during welding. If such high dimensional accuracy cannot be ensured, it becomes necessary to correct the steel members at the construction site, which significantly impairs the workability at the site.

[0024] In addition, in order to fix the floor slab to the steel beam, the shear connector provided on the upper surface of the steel beam is generally installed avoiding the splice plate. However, in the structure described in Patent Document 3, the splice plate for joining the upper flange of the steel beam to the through diaphragm on the upper side of the steel beam is located at the end of the steel beam close to the side of the steel column, so that the shear connector cannot be provided at the end of the steel beam, and it is considered that the composite effect of the steel beam and the floor slab will be reduced.

[0025] In this way, in the non-bracket type joint structure between steel beams and steel columns that is widely used in high-rise buildings, proposals have been made to ensure the deformation capacity of the steel beam by moving the on-site welding position of the bottom flange of the end of the steel beam away from the side of the steel column, or to bolt the bottom flange of the steel beam to a bracket already attached to the steel column, making on-site welding unnecessary and ensuring on-site workability, etc. However, all of these proposals still have problems, such as an increase in the amount of processing work required when manufacturing the steel members, an increase in the number of members that need to be attached to the steel column in advance, and an increase in the dimensional accuracy required for the steel members.

[0026] In view of the above problems, the present invention aims to provide a joint structure between a steel beam and a steel column that can improve on-site workability while ensuring the deformation capacity of the steel beam, and an H-shaped steel used therein. [Means for solving the problem]

[0027] In order to solve the above problems, the present invention has the following features.

[0028] [1] A connection structure between a steel beam having an H-shaped cross-sectional shape consisting of an upper flange, a lower flange, and a web, and a steel column, wherein the steel column is provided with an upper diaphragm and a lower diaphragm at the height where the upper flange and the lower flange of the steel beam are attached, respectively, the end of the steel beam that is connected to the steel column is not provided with the lower flange, and a connection plate is provided on the side of the lower diaphragm so as to protrude from the side of the steel column in the material axis direction of the steel beam toward the bottom flange of the steel beam, the upper flange of the steel beam is welded to the side of the steel column or the upper diaphragm, the bottom flange of the steel beam is friction-connected to the connection plate with a high-strength bolt, and there is no connection between the web of the steel beam and the connection plate.

[0029] [2] The joint structure between a steel beam and a steel column described in [1], wherein the upper diaphragm and the lower diaphragm are internal diaphragms or through diaphragms.

[0030] [3] A joint structure between a steel beam and a steel column described in [1] or [2], wherein the joint plate and the lower diaphragm are integrally formed from a single steel plate.

[0031] [4] A joint structure between a steel beam and a steel column described in any of [1] to [3], wherein the steel beam is a welded H-shaped cross-section beam.

[0032] [5] A joint structure between a steel beam and a steel column described in any of [1] to [4], wherein the distance between the end of the splice plate of the high-strength bolt friction joint and the side of the steel column is 400 mm or less.

[0033] [6] A joint structure between a steel beam and a steel column described in any of [1] to [5], wherein the strength of the joint plate is higher than the strength of the bottom flange of the steel beam.

[0034] [7] An H-shaped steel used as a steel beam in a joint structure between a steel beam and a steel column described in any one of [1] to [6], wherein the H-shaped steel does not have the lower flange at the end in the axial direction. Effect of the Invention

[0035] According to the joint structure between a steel beam and a steel column of the present invention, the lower flange of the steel beam is friction-joined with a high-strength bolt to a joint plate that protrudes from the side of the steel column, thereby improving on-site workability while ensuring the deformation capacity of the steel beam.

[0036] That is, in the joint structure between a steel beam and a steel column of the present invention, the joint between the upper flange and web portion of the steel beam and the steel column is ensured to be as easy to install as in the conventional case.

[0037] In addition, with regard to the joining of the bottom flange of the steel beam to the steel column, the joining plate provided on the side of the bottom diaphragm can be welded to the steel column or the bottom diaphragm in a steel factory with a good working environment and without interference from gusset plates or beam webs. This ensures the quality of the welded part of the bottom flange of the end of the steel beam, which is subjected to a large bending moment during an earthquake, and reduces the risk of early fracture of the welded part. In addition, since there is no joining between the web of the steel beam and the joining plate, fracture does not occur starting from the scallop provided near the bottom flange of the web of the end of the steel beam. Furthermore, the splice plate used in the high-strength bolt friction joining of the bottom flange of the steel beam and the joining plate exerts a buckling stiffening effect on the joining plate against the compressive force generated in the bottom flange due to the bending moment acting on the steel beam, so that the buckling of the joining plate can be suppressed. In this way, the deformation capacity of the steel beam is sufficiently ensured. In addition, at the construction site, the bottom flange of the steel beam can be bolted to the connecting plate, eliminating the need for on-site welding of the bottom flange, improving on-site workability.

[0038] In addition, in the joint structure between a steel beam and a steel column of the present invention, the friction joint surface of the high-strength bolt friction joint between the bottom flange of the steel beam and the joint plate can be two surfaces, the top and bottom, and the number of bolts required for the high-strength bolt friction joint is half that of a case where the friction joint surface is only one surface. Therefore, the protruding length of the joint plate protruding from the side surface of the steel column can be kept small, and the weight and dimensions of the steel column can be reduced.

[0039] Furthermore, in the joint structure between a steel beam and a steel column of the present invention, the lower flange of the end of the steel beam is joined to the joint plate at the construction site by friction jointing with high-strength bolts, while the upper flange of the end of the steel beam is joined to the steel beam by welding. At this time, the lower flange of the steel beam and the joint plate need to be aligned in the height direction, but a dimensional error of several millimeters in the height direction is allowed between the upper flange of the steel beam and the upper diaphragm. This is because the upper diaphragm is generally made of a material several millimeters thicker than the upper flange of the steel beam. Therefore, the dimensional accuracy required for the steel member may be lower than when both the lower flange and the upper flange of the steel beam are joined by bolts.

[0040] In addition, in the joint structure between a steel beam and a steel column of the present invention, the web at the end of the steel beam may be bolted to a gusset plate provided on the side of the steel column, but even in this case, a dimensional error of about 2 mm in the height direction is allowed between the web of the steel beam and the gusset plate. This is because the size of the bolt hole provided for high-strength bolt friction joints is generally the bolt diameter + 2 mm. In this way, the joint structure between a steel beam and a steel column of the present invention has excellent workability because there are no strict restrictions on dimensional errors during the manufacture of steel members.

[0041] In addition, in the joint structure between a steel beam and a steel column of the present invention, a shear connector can be provided on the upper flange of the steel beam up to a position near the side of the steel column, so that the composite effect of the steel beam and the floor slab can be fully obtained.

[0042] Furthermore, by using the H-shaped steel of the present invention, a joint structure between a steel beam and a steel column of the present invention can be easily constructed. [Brief description of the drawings]

[0043] [Figure 1] FIG. 1(a) to FIG. 1(f) are diagrams showing a first embodiment of a joint structure between a steel beam and a steel column according to the present invention and an H-shaped steel used therein. [Diagram 2]FIG. 2 is a diagram showing a second embodiment of the joint structure between a steel beam and a steel column according to the present invention and an H-shaped steel used therein. [Diagram 3] FIG. 3 is a diagram showing a third embodiment of the joint structure between a steel beam and a steel column according to the present invention and an H-shaped steel used therein. [Figure 4] FIG. 4 is a diagram showing a fourth embodiment of the joint structure between a steel beam and a steel column according to the present invention and an H-shaped steel used therein. [Diagram 5] 5(a) to 5(e) are diagrams showing a fifth embodiment of the joint structure between a steel beam and a steel column of the present invention and an H-shaped steel used therein. [Figure 6] 6(a) to 6(e) are diagrams showing a sixth embodiment of the joint structure between a steel beam and a steel column of the present invention and an H-shaped steel used therein. [Figure 7] 7(a) to 7(e) are diagrams showing a seventh embodiment of the joint structure between a steel beam and a steel column of the present invention and an H-shaped steel used therein. [Figure 8] FIG. 8 is a diagram showing an analytical model of a numerical analysis carried out to verify the effect of the joint structure between a steel beam and a steel column according to the present invention. [Figure 9] FIG. 9 is a diagram showing the relationship between the bending moment and the rotation angle of a steel beam, which is obtained from a numerical analysis carried out to verify the effect of the joint structure between a steel beam and a steel column of the present invention. [Figure 10] FIG. 10 is a contour diagram showing the distribution of deformation and equivalent plastic strain obtained from a numerical analysis carried out to verify the effect of the joint structure between a steel beam and a steel column of the present invention. [Figure 11] FIG. 11 is a contour diagram showing the distribution of deformation and equivalent plastic strain obtained from a numerical analysis carried out to verify the effect of the joint structure between a steel beam and a steel column of the present invention. [Figure 12] 12(a) to 12(d) are diagrams showing an example of a conventional joint structure between a steel beam and a steel column. [Figure 13] 13(a) to 13(d) are diagrams showing another example of a conventional joint structure between a steel beam and a steel column. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Hereinafter, with reference to the drawings, an embodiment of a joint structure between a steel beam and a steel column according to the present invention and an H-shaped steel used therein will be described in detail. [First embodiment] Fig. 1(a) to Fig. 1(f) show a joint structure between a steel beam and a steel column according to a first embodiment of the present invention, and an H-shaped steel used therein. Fig. 1(a) to Fig. 1(c) are a side view of a steel column 2A, a side view of a steel beam 1A, and a side view of the joint structure between a steel beam and a steel column, respectively. Fig. 1(d) to Fig. 1(f) are a cross-sectional view taken along line DD, line EE, and line FF in Fig. 1(c), respectively.

[0045] The joint structure between a steel beam and a steel column of this embodiment is used for a joint between a steel beam 1A having an H-shaped cross section consisting of an upper flange 11, a lower flange 12, and a web 13, and a steel column 2A. The steel beam 1A is an H-shaped steel manufactured by rolling, and is formed so that the bottom flange 12 at the end in the material axial direction is not provided by previously cutting off the bottom flange 12 at the end in the material axial direction, thereby constituting the H-shaped steel according to this embodiment. Alternatively, instead of this, a welded assembled H-shaped section beam formed by welding together the upper flange 11 and web 13 and the bottom flange 12 whose length in the material axial direction is shorter than those of the upper flange 11 and web 13 may be used as the steel beam 1A.

[0046] 1(a), in order to transmit stress from a steel beam 1A to a steel column 2A, an upper diaphragm 21a and a lower diaphragm 22a are provided at the heights of the steel column 2A where the upper flange 11 and the lower flange 12 of the steel beam 1A are attached, respectively. In this embodiment, the upper diaphragm 21a and the lower diaphragm 22a are of the internal diaphragm type.

[0047] As shown in FIG. 1(a), a connecting plate 23a is welded to the side of the steel column 2A at a position to the side of the lower diaphragm 22a, so as to protrude from the side of the steel column 2A toward the lower flange 12 of the steel beam 1A in the material axis direction of the steel beam 1A. The connecting plate 23a is made of a steel plate having the same plate thickness as the lower flange 12 of the steel beam 1A. Furthermore, a gusset plate 24 is welded to the side of the steel column 2A at a position between the upper diaphragm 21a and the lower diaphragm 22a, so as to protrude from the side of the steel column 2A toward the lower flange 12 of the steel beam 1A in the material axis direction of the steel beam 1A. The upper diaphragm 21a, the lower diaphragm 22a, the connecting plate 23a, and the gusset plate 24 are welded to the steel column 2A in advance when the steel column 2A is manufactured in a steel factory, and the steel column 2A manufactured in this state is carried to the construction site.

[0048] As shown in Fig. 1(b), the end 10 of the steel beam 1A that is joined to the steel column 2A is not provided with a bottom flange 12. As shown in Fig. 1(c), when the steel beam 1A is joined to the steel column 2A, a joining plate 23a welded in advance to the side surface of the steel column 2A fits into the part of the steel beam 1A where the bottom flange 12 is not provided. In other words, the bottom flange 12 of the steel beam 1A is formed shorter than the top flange 11 by the protruding length of the joining plate 23a from the side surface of the steel column 2A in the material axis direction of the steel beam 1A.

[0049] Then, as shown in Figs. 1(c) to 1(f), the steel beam 1A and the steel column 2A are joined together at the construction site.

[0050] Specifically, the web 13 of the steel beam 1A is overlapped on the gusset plate 24 pre-welded to the side of the steel column 2A while aligning the two so that the joining plate 23a pre-welded to the side of the steel column 2A fits into the portion of the steel beam 1A where the lower flange 12 is not provided.

[0051] Splice plates 31, 32 are placed above and below the bottom flange 12 and the joining plate 23a of the steel beam 1A, and the bottom flange 12 of the steel beam 1A is friction-joined to the joining plate 23a provided on the steel column 2A by the bolts 4 via these splice plates 31, 32. Also, the web 13 of the steel beam 1A is friction-joined to the gusset plate 24 provided on the steel beam by the bolts 4. Furthermore, the top flange 11 of the steel beam 1A is welded to the side of the steel column 2A on site. There is no joint between the lower side of the web 13 at the end 10 of the steel beam 1A and the joining plate 23a.

[0052] Here, a dimensional error of about 2 mm in the height direction is permitted for the bolt joint between the web 13 of the steel beam 1A and the gusset plate 24. This is because the size of the bolt hole provided for the bolt joint is generally set to the bolt diameter + 2 mm.

[0053] As described above, when the splice plates 31, 32 are placed on the upper and lower surfaces of the lower flange 12 and the joining plate 23a to perform high-strength bolt friction joining, the number of bolts required for the high-strength bolt friction joining is half that required when the friction joining surface is only one surface, since two friction joining surfaces are formed. Therefore, the protruding length of the joining plate 23a from the side surface of the steel column 2A can be kept small, and the weight and dimensions of the steel column 2A are reduced, making it easier to transport and store.

[0054] In addition, scallops 131 and 132 are provided on the web 13 at the end of the steel beam 1A to pass the backing metal 5 of the welded portion between the side surface of the steel column 2A and the joining plate 23a and the backing metal 6 of the welded portion between the side surface of the steel column 2A and the upper flange 11 of the steel beam 1A. The shape of the scallops 131 and 132 can be a composite arc shape combining, for example, an arc with a radius of 35 mm and an arc with a radius of 10 mm. Among these, the welding between the side surface of the steel column 2A and the joining plate 23a is performed not at a construction site but at a steel factory where the steel column 2A is manufactured, so that the scallop 132 provided near the joining plate 23a does not have to interfere with the backing metal 5 of the welded portion of the joining plate 23a and may be smaller in size than the scallop 132 provided near the upper flange 11.

[0055] In the joint structure between a steel beam and a steel column of this embodiment, the distance X between the ends of the splice plates 31, 32 of the high-strength bolt friction joint and the side surface of the steel column 2A is set to 400 mm or less. The bottom flange 12 in the center of the steel beam 1A has a web 13 connected to the center in the width direction of the bottom flange 12, while the joint plate 23a located below the end 10 of the steel beam 1A is not joined to the web 13 of the steel beam 1A. Therefore, buckling may occur in the part of the joint plate 23a that is not restrained by the splice plates 31, 32.

[0056] Therefore, as in this embodiment, it is preferable to limit the distance X from the ends of the splice plates 31, 32 that restrain the joining plate 23a to the side surface of the steel column 2A to 400 mm or less, thereby reducing the length of the portion of the joining plate 23a that is not restrained by the splice plates 31, 32. In this way, when a compressive force is applied to the joining plate 23a below the end 10 of the steel beam 1A due to a bending moment acting on the steel beam 1A during an earthquake, the buckling length is shortened, enhancing the effect of suppressing buckling of the joining plate 23a, and improving the strength and deformation capacity of the steel beam 1A. However, in cases where the plate thicknesses of the upper flange 11, the lower flange 12, and the web 13 of the steel beam 1A are small and the steel beam 1A buckles before the joining plate 23a, or where the stress acting on the steel beam 1A is small to begin with, it is not necessarily necessary to ensure the buckling stiffening effect of the joining plate 23a by the splice plates 31, 32, and the distance X may exceed 400 mm.

[0057] In the joint structure between the steel beam and the steel column of this embodiment, the strength of the joint plate 23a is set higher than the strength of the bottom flange 12 of the steel beam 1A. This is preferable because it reduces the stress generated in the joint plate 23a on the lower side of the end 10 of the steel beam 1A, suppressing breakage at the welded portion between the side surface of the steel column 2A and the joint plate 23a, and improving the deformation capacity of the steel beam 1A. [Second embodiment] FIG. 2 shows a joint structure between a steel beam and a steel column according to a second embodiment of the present invention, and an H-shaped steel used therein.

[0058] As shown in Fig. 2, in the joint structure between a steel beam and a steel column of this embodiment, the upper diaphragm 21b and the lower diaphragm 22b provided on the steel column 2B are of a through diaphragm type. A joint plate 23b arranged horizontally is welded to the edge of the lower diaphragm 22b so as to protrude from the side surface of the steel column 2B toward the lower flange 12 of the steel beam 1B in the material axis direction of the steel beam 1B. The upper diaphragm 21b, the lower diaphragm 22b, the joint plate 23b, and the gusset plate 24 are welded to the steel column 2B in advance when the steel column 2B is manufactured at a steel factory. The upper flange 11 of the steel beam 1B is welded on-site to the upper diaphragm 21b provided on the steel column 2B.

[0059] In other respects, the joint structure between the steel beam and the steel column in this embodiment is configured similarly to the first embodiment. [Third embodiment] FIG. 3 shows a joint structure between a steel beam and a steel column according to a third embodiment of the present invention, and an H-shaped steel used therein.

[0060] As shown in Fig. 3, in the joint structure between a steel beam and a steel column of this embodiment, a part of the lower diaphragm provided on the steel column 2C protrudes largely from the side surface of the steel column 2C in the material axis direction of the steel beam 1A, and this protruding part serves as a joint plate 23c. In other words, the joint plate 23c and the lower diaphragm are integrally formed from a single steel plate.

[0061] In this embodiment, when the joining plate 23c and the lower diaphragm are formed integrally from a single steel plate, there is no weld between the joining plate 23c and the lower diaphragm, and there is no risk of breakage at this weld, thereby further improving the deformation capacity of the steel beam 1A.

[0062] In other respects, the joint structure between the steel beam and the steel column in this embodiment is configured similarly to the second embodiment. [Fourth embodiment] FIG. 4 shows a joint structure between a steel beam and a steel column according to a fourth embodiment of the present invention, and an H-shaped steel used therein.

[0063] As shown in Fig. 4, in the joint structure between a steel beam and a steel column of this embodiment, the protruding length of the joint plate 23d provided on the side of the lower diaphragm 22b of the steel column 2D from the side of the steel column 2D in the material axis direction of the steel beam 1C is set to be larger than the protruding length of the joint plate 23a of the first embodiment from the side of the steel column 2A in the material axis direction of the steel beam 1A. The length of the part of the steel beam 1C where the lower flange 12 is not provided is shorter by the protruding length of the joint plate 23d from the side of the steel column 2D in the material axis direction of the steel beam 1C. As a result, the distance X between the end of the splice plates 31, 32 of the high-strength bolt friction joint and the side of the steel column 2D is set to be larger than that of the first embodiment.

[0064] In the joint structure between the steel beam and the steel column of this embodiment, as shown in Fig. 4, the length of the portion of the joint plate 23d that is not restrained by the splice plates 31 and 32 is longer than that of the first embodiment. Even in such a structure, by performing welding of the joint plate 23d to the lower diaphragm 22b in a steel factory with a good working environment, the quality of the weld between the joint plate 23d on the lower side of the end of the steel beam 1C, which is subjected to a large bending moment during an earthquake, and the lower diaphragm 22b is ensured, and the risk of early fracture of the weld is reduced. In addition, since there is no joint between the web 13 of the steel beam 1C and the joint plate 23d, no fracture will occur starting from the scallop 132 provided on the lower side of the web 13 at the end of the steel beam 1C.

[0065] However, in this embodiment, since the distance X between the ends of the splice plates 31, 32 of the high-strength bolt friction joint and the side surface of the steel column 2D is large, the buckling length when a compressive force is applied to the joint plate 23d below the end 10 of the steel beam 1C due to the bending moment acting on the steel beam 1C during an earthquake is relatively long, and there is a risk that the joint plate 23d will buckle as shown in Fig. 4. Therefore, even when the distance X between the ends of the splice plates 31, 32 of the high-strength bolt friction joint and the side surface of the steel column 2D is set large as in this embodiment, it is preferable that the distance X be set to 400 mm or less. However, in cases where the plate thicknesses of the upper flange 11, the lower flange 12 and the web 13 of the steel beam 1C are small and the steel beam 1C buckles before the joining plate 23d, or where the stress acting on the steel beam 1C is small to begin with, it is not necessarily necessary to ensure the buckling stiffening effect of the joining plate 23d by the splice plates 31, 32, and the distance X may exceed 400 mm.

[0066] In other respects, the joint structure between the steel beam and the steel column in this embodiment is configured similarly to the second embodiment. [Fifth embodiment] Fig. 5(a) to Fig. 5(e) show a joint structure between a steel beam and a steel column according to a fifth embodiment of the present invention, and an H-shaped steel used therein. Fig. 5(a) and Fig. 5(b) are a side view and a horizontal cross-sectional view (a view looking up from below at the joint between the steel beam and the steel column) of the joint structure between the steel beam and the steel column of this embodiment, and Fig. 5(c) to Fig. 5(e) are cross-sectional views along the lines CC, DD, and EE in Fig. 5(a), respectively.

[0067] 5(b), in the joint structure between a steel beam and a steel column of this embodiment, the width of the joint plate 23e welded to the side surface of the steel column 2E is increased at a portion close to the side surface of the steel column 2E. This is preferable because it reduces stress generated in the joint plate 23e on the lower side of the end portion of the steel beam 1A, suppresses breakage at the welded portion between the side surface of the steel column 2E and the joint plate 23e, and improves the deformation capacity of the steel beam 1A.

[0068] In the joint structure between a steel beam and a steel column of this embodiment, the width of the splice plates 33, 34 is also expanded in the same manner as the joint plate 23e. This makes it possible to increase the number of bolts required for high-strength bolt friction joints in the width direction of the joint plate 23e and the splice plates 33, 34. This is preferable because it makes it possible to keep small the protruding length of the joint plate 23e in the axial direction of the steel beam 1A from the side surface of the steel column 2E while maintaining the area of ​​the friction joint surface of the high-strength bolt friction joint.

[0069] In other respects, the joint structure between the steel beam and the steel column in this embodiment is configured similarly to the first embodiment. [Sixth embodiment] Figures 6(a) to 6(e) show a joint structure between a steel beam and a steel column according to a sixth embodiment of the present invention, and an H-shaped steel used therein. Figures 6(a) and 6(b) are a side view and a horizontal cross-sectional view (a view looking up from below at the joint between the steel beam and the steel column) of the joint structure between the steel beam and the steel column of this embodiment, and Figures 6(c) to 6(e) are cross-sectional views along lines CC, DD, and EE in Figure 6(a), respectively.

[0070] As shown in Figures 6(a) to 6(c), in the joint structure between a steel beam and a steel column of this embodiment, a warp prevention member 26 for preventing warping of the joint plate 23e is welded in advance to the steel column 2F when the steel column 2F is manufactured at a steel factory, perpendicular to the joint plate 23e and the side surface of the steel column 2F so as to connect the upper surface of the widened portion of the joint plate 23e in the fifth embodiment to the side surface of the steel column 2F.

[0071] When welding the joining plate 23e to the side of the steel column 2F in a steel frame factory, if a general V-shaped groove is provided in the joining plate 23e and welding is performed, one side of the joining plate 23e may shrink significantly due to the difference in heat input between the upper surface side and the lower surface side of the joining plate 23e, and the joining plate 23e may warp to one side. Therefore, providing a warp prevention member 26 as in this embodiment is preferable because it makes it easier to ensure the dimensional accuracy of the joining plate 23e.

[0072] In other respects, the joint structure between the steel beam and the steel column in this embodiment is configured similarly to the fifth embodiment. [Seventh embodiment] Figures 7(a) to 7(e) show a joint structure between a steel beam and a steel column according to a seventh embodiment of the present invention, and an H-shaped steel used therein. Figures 7(a) and 7(b) are a side view and a horizontal cross-sectional view (a view looking up from below at the joint between a steel beam 1A and a steel column 2G) of the joint structure between a steel beam and a steel column of this embodiment, and Figures 7(c) to 7(e) are cross-sectional views taken along lines CC, DD, and EE in Figure 7(a), respectively.

[0073] As shown in Figures 7(a) to 7(c), in the joint structure between a steel beam and a steel column in this embodiment, the gusset plate 25 provided on the side of the steel column 2G extends downward, and when the steel column 2G is manufactured at the steel factory, the lower edge of the gusset plate 25 is welded to the upper surface of the joint plate 23a.

[0074] In this manner, similarly to the warp prevention member 26 of the sixth embodiment, when the joining plate 23a is welded to the side of the steel column 2G at a steel frame factory, a typical R-shaped groove is made in the joining plate 23a and welded. Due to the difference in heat input between the upper and lower sides of the joining plate 23a, one side of the joining plate 23a shrinks significantly, which prevents the joining plate 23a from warping to one side, making it easier to ensure the dimensional accuracy of the joining plate 23a, which is preferable.

[0075] In other respects, the joint structure between the steel beam and the steel column in this embodiment is configured similarly to the second embodiment.

[0076] In each of the above embodiments, the upper diaphragm and the lower diaphragm are described as being of the internal diaphragm type or the through diaphragm type, but the joint structure between a steel beam and a steel column of the present invention is also applicable to cases where the upper diaphragm and the lower diaphragm are of the external diaphragm type.

[0077] In addition, in each of the above embodiments, a case has been described in which the web of a steel beam is bolted to a gusset plate that has been pre-welded to the side of a steel column. However, the joint structure between a steel beam and a steel column of the present invention is also applicable to a case in which a gusset plate is not provided on the steel column and the web at the end of the steel beam is welded on-site to the side of the steel beam. EXAMPLES

[0078] In the joint structure between a steel beam and a steel column of the present invention, when the plate thickness of the upper flange, the lower flange and the web of the steel beam is small and the steel beam buckles before the joint plate, or when the stress acting on the steel beam is small in the first place, it is not necessarily necessary to ensure the buckling stiffening effect of the joint plate by the splice plate. However, when the plate thickness of the upper flange, the lower flange and the web of the steel beam is relatively large and the stress acting on the steel beam is relatively large, the bending moment acting on the steel beam during an earthquake applies a compressive force to the joint plate on the lower side of the end of the steel beam, which may cause local buckling in the part of the joint plate that is not restrained by the splice plate, thereby reducing the deformation capacity of the steel beam. Therefore, as described above, in the joint structure between a steel beam and a steel column of the present invention, it is preferable that the distance X between the end of the splice plate of the high-strength bolt friction joint and the side of the steel column is set to 400 mm or less.

[0079] In order to confirm the effect of setting the distance between the end of the splice plate and the side of the steel column to 400 mm or less, a numerical analysis was carried out using the finite element method, which is described below.

[0080] Figure 8 shows the shape of the analytical model targeted in this numerical analysis. In this numerical analysis, a T-shaped analytical model simulating the joint structure between a steel beam and a steel column in the second embodiment shown in Figure 2 was analyzed. Specifically, the cross-sectional size of the steel beam 1B was set to 900 mm in beam depth, 350 mm in beam width, 19 mm in web thickness, 36 mm in flange thickness, and 4500 mm in length L. The cross-sectional size of the steel column 2B was set to external dimensions of 800 mm x 800 mm, wall thickness of 40 mm, and height H of 4000 mm.

[0081] In addition, upper diaphragm 21b and lower diaphragm 22b of a through diaphragm type were provided on steel column 2B at the height where upper flange 11 and lower flange 12 of steel beam 1B were attached, with a center-to-center distance of plate thickness of 864 mm.

[0082] Furthermore, the joining plate 23b has a width of 350 mm, a thickness of 36 mm, and a thickness of 25 mm for the gusset plate 24. The size of the splice plate 31 provided on the outside of the bottom flange 12 of the steel beam 1B is a width of 350 mm, a thickness of 36 mm, and a length of 530 mm, and the size of the splice plate 32 provided on the inside of the top flange 11 and the bottom flange 12 of the steel beam 1B, i.e., on both sides of the web 13, is a width of 140 mm, a thickness of 36 mm, and a length of 530 mm.

[0083] The steel beam 1B, the steel column 2B, the gusset plate 24 and the splice plates 31 and 32 have a strength of 490N / mm 2 The material properties were set to simulate those of a 550N / mm 2 The material properties were set to simulate those of grade steel plate.

[0084] Then, as shown in Table 1, a numerical analysis was performed on analytical models (Test Nos. 1 to 5) in which the distance X between the ends of the splice plates 31, 32 and the side surface of the steel column 2B was used as a parameter, and this distance X was changed to five different values, 100 mm, 200 mm, 400 mm, 600 mm, and 800 mm. For comparison, a similar numerical analysis was also performed on a conventional non-bracket type joint structure between a steel beam and a steel column (Test No. 6) in which the bottom flange 12 of a steel beam 1B not provided with a joint plate 23b is directly welded to the side surface of the steel column 2B.

[0085] [Table 1]

[0086] Then, assuming that a bending moment acts on the steel beam 1B during an earthquake, generating compressive force in the lower connecting plate 23b or the lower flange 12 at the end of the steel beam 1B, a numerical analysis was performed on the T-shaped analytical model shown in Figure 8, where the lower end of the steel column 2B is pin-supported and the upper end is pin-roller supported, while a downward shear force is input to the free end of the steel beam 1B that is not connected to the steel column 2B, and this shear force is gradually increased.

[0087] Figure 9 shows the relationship between the bending moment acting on the end of steel beam 1B and the beam rotation angle of steel beam 1B (displacement of the free end of steel beam 1B / length of steel beam 1B) obtained from this numerical analysis.

[0088] As shown in Figure 9, in Tests Nos. 1 to 3, in which the distance between the ends of the splice plates 31, 32 and the side of the steel column 2B was 400 mm or less, the relationship between the bending moment and the beam rotation angle showed a stable history equivalent to that of Test No. 6, which simulated a conventional non-bracket type joint structure between a steel beam and a steel column. In contrast, in Tests Nos. 4 and 5, in which the distance between the ends of the splice plates 31, 32 and the side of the steel column 2B was 600 mm or 800 mm, local buckling occurred in the joint plate 23b during the analysis, resulting in a decrease in the bending strength of the steel beam 1B.

[0089] Figures 10 and 11 show the contour diagrams of the numerical analysis results of the distribution of deformation and equivalent plastic strain occurring near the joint between steel beam 1B and steel column 2B when the beam rotation angle of steel beam 1B became approximately 0.04 rad in tests No. 3 and 5, respectively.

[0090] As shown in Fig. 10, in test No. 3 where the distance between the ends of the splice plates 31, 32 and the side of the steel column 2B was 400 mm, buckling of the connection plate 23a was suppressed. In contrast, as shown in Fig. 11, in test No. 5 where the distance between the ends of the splice plates 31, 32 and the side of the steel column 2B was 800 mm, buckling occurred in the connection plate 23a. This confirmed that by restricting the distance between the ends of the splice plates 31, 32 of the high-strength bolt friction joint and the side of the steel column 2B to 400 mm or less, early buckling of the connection plate 23a was suppressed, and the deformation capacity of the steel beam 1B was increased.

[0091] 10 and 11, in the web 13 of the steel beam 1B, large plastic strain was generated around the scallop 131 provided near the top flange 11, whereas the plastic strain generated around the scallop 132 provided near the bottom flange 12 was relatively small. This confirmed that the joint structure between the steel beam and the steel column of the present invention can effectively suppress fracture originating from the scallop 132 provided near the bottom flange 12 of the steel beam 1B. It is considered that such an effect is obtained because the joint structure between the steel beam and the steel column of the present invention does not join the web 13 at the end of the steel beam 1B to the joining plate 23a.

[0092] 10 and 11, the strain generated in the lower joint plate 23b of the end of the steel beam 1B and the strain generated in the upper flange 11 of the end 10 of the steel beam 1B are compared, and the strain generated in the joint plate 23b is smaller. 2 It has been confirmed that the use of high-strength steel of this class reduces the strain generated in the joining plate 23b at the end of the steel beam 1B, thereby improving the deformation capacity of the steel beam 1B. [Explanation of symbols]

[0093] 1A~1C Steel beams (H-shaped steel) 10 End of steel beam 11 Upper flange 12 Bottom flange 13. Web 131, 132 Scallop 2A~2G Steel columns 21a, 21b Upper diaphragm 22a, 22b Lower diaphragm 23a~23e Joining plates 24, 25 Gusset plate 26 Anti-warping material 31~34 Splice plate 4 Volts 5 Backing plate X: The distance between the end of the splice plate of a high-strength bolt friction joint and the side of the steel column

Claims

1. A joint structure between a steel beam having an H-shaped cross section consisting of an upper flange, a lower flange, and a web, and a steel column, The steel column is provided with an upper diaphragm and a lower diaphragm at heights where the upper flange and the lower flange of the steel beam are attached, respectively; The end of the steel beam that is joined to the steel column is not provided with the lower flange, and only the upper flange and the web are provided, A joining plate is provided on the side of the lower diaphragm so as to protrude from the side surface of the steel column in the material axis direction of the steel beam toward the lower flange of the steel beam and enter the portion of the end of the steel beam where the lower flange is not provided, The upper flange of the steel beam is welded to the side surface or the upper diaphragm of the steel column; The lower flange of the steel beam is friction-connected to the connecting plate by a high-strength bolt, A joint structure between a steel beam and a steel column, in which there is no joint between the web of the steel beam and the joint plate.

2. The joint structure between a steel beam and a steel column according to claim 1 , wherein the upper diaphragm and the lower diaphragm are internal diaphragms or through diaphragms.

3. 3. The joint structure between a steel beam and a steel column according to claim 1, wherein the joint plate and the lower diaphragm are integrally formed from a single steel plate.

4. The joint structure between a steel beam and a steel column according to any one of claims 1 to 3, wherein the steel beam is a welded H-shaped cross-section beam.

5. The joint structure between a steel beam and a steel column according to any one of claims 1 to 4, wherein the distance between the end of the splice plate of the high-strength bolt friction joint and the side of the steel column is 400 mm or less.

6. The joint structure between a steel beam and a steel column according to any one of claims 1 to 5, wherein the strength of the joint plate is higher than the strength of the bottom flange of the steel beam.

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