Joint structure of iron framework and coupling member for connecting rectangular steel beam to rectangular steel column

[0001] 1. Field of the Invention

[0002] The present invention relates to a joint structure of iron framework and a coupling member for connecting rectangular steel beam to rectangular steel column, and specifically, relates to a joint structure of iron framework and a coupling member for connecting a rectangular steel beam to a rectangular steel column capable of enhancing workability and strength.

[0003] 2. Description of the Related Art

[0004] Conventionally, there is a joint structure of iron framework for connecting an H-shaped steel beam to a hollow rectangular steel column (for example, see non-patent document 1).

[0005] In this joint structure, some midpoint of a hollow rectangular steel column is cut. Then, an H-shaped steel beam is connected to the hollow rectangular steel column by welding via a member called diaphragm so as to enhance the rigidity of the joint therebetween.

[0006] However, this joint structure of iron framework requires cutting of some midpoint of a hollow rectangular steel column, and this cutting operation lowers the workability. In addition, the H-shaped steel beam is connected to the hollow rectangular steel column, and this beam has a problem that it is weak against a load applied thereto from its side direction (i.e. horizontal load).

[0007] [Non-patent document 1] “Easy-to-make Iron framework design demonstrated by illustrative examples”, on page 47, edited by Japanese Society of Steel Construction, (second edition)

[0008] To solve the abovementioned problems, an object of the present invention is to provide a joint structure of iron framework, and a coupling member for connecting a rectangular steel beam to a rectangular steel column.

[0009] To achieve the object described above, according to the present invention, there is provided a joint structure of iron framework for connecting a hollow rectangular steel beam to a hollow rectangular steel column via a coupling member, wherein the coupling member comprising: a rectangular cylinder fitted to an outer periphery of the hollow rectangular steel column and firmly attached to the hollow rectangular steel column; a U-shaped receiving member provided to a side surface of the rectangular cylinder for connecting the hollow rectangular steel beam, the U-shaped receiving member having a bottom portion protruded from the side surface of the rectangular cylinder, having a U-shaped opening portion located to face upward, having a U-shaped end surface firmly attached to the side surface of the rectangular cylinder; and a lid firmly attached to the U-shaped receiving member in a state of covering the upper surface of the hollow rectangular steel beam mounted in the U-shaped receiving member.

[0010] According to the invention claimed in claim 2, in the joint structure of iron framework claimed in claim 1, a slit is formed on each side surface of a rectangular cylinder, and the rectangular cylinder is firmly attached to a hollow rectangular steel column via the slit.

[0011] According to the invention claimed in claim 3, in the joint structure of iron framework claimed in claim 1, the bottom portion of the U-shaped receiving member is formed with a bottom bolt hole for allowing a bolt to pass therethrough, a right rising portion which is one of the sides rising from the bottom portion is formed with a right bolt hole for allowing a bolt to pass therethrough, and a left rising portion which is the other side rising from the bottom portion is formed with a left bolt hole, respectively, and wherein the bottom surface of the hollow rectangular steel beam is formed with a bottom surface bolt hole corresponding to the bottom bolt hole, and the left side surface of the hollow rectangular steel beam is formed with a left side surface bolt hole corresponding to the left bolt hole, and a left side surface of the hollow rectangular steel beam is formed with a left side surface bolt hole corresponding to the left bolt hole, wherein the upper surface of the hollow rectangular steel beam is formed with a hand insertion hole of a size allowing a hand to enter therein, and wherein the U-shaped receiving member and the hollow rectangular steel beam are connected to each other by the bottom bolt and the bottom nut via the bottom bolt hole and the bottom surface bolt hole, by the left bolt and the left nut via the left bolt hole and the left side surface bolt hole, and by the right bolt and the right nut via the right bolt hole and the right side surface bolt hole.

[0012] According to the invention claimed in claim 4, in the joint structure of iron framework claimed in claim 1, the bottom portion of the U-shaped receiving member is formed with a bottom bolt hole for allowing a bolt to pass therethrough, a surface of a right rising portion which is one of the sides rising from the bottom portion of the U-shaped receiving member is formed with a right bolt hole for allowing a bolt to pass therethrough, and a surface of a left rising portion which is the other side rising from the bottom portion is formed with a left bolt hole, respectively; wherein the bottom surface of the hollow rectangular steel beam is formed with a bottom surface bolt hole corresponding to the bottom bolt hole, and the left side surface of the hollow rectangular steel beam is formed with a left side surface bolt hole corresponding to the left bolt hole, and a left side surface of the hollow rectangular steel beam is formed with a left side surface bolt hole corresponding to the left bolt hole; wherein the side surface of the hollow rectangular steel beam is formed with a hand insertion hole of a size allowing a hand to enter therein, wherein a surface of the right rising portion or a surface of the left rising portion is formed with a hand insertion hole of rising portion's side surface corresponding to the hand insertion hole of rectangular beam's side surface; and wherein the U-shaped receiving member and the hollow rectangular steel beam are connected to each other by the bottom bolt and the bottom nut via the bottom bolt hole and the bottom surface bolt hole, by the left bolt and the left nut via the left bolt hole and the left side surface bolt hole, and by the right bolt and the right nut via the right bolt hole and the right side surface bolt hole.

[0013] According to the invention claimed in claim 5, in the joint structure of iron framework claimed in claim 1, a lid is in a rectangular shape when viewed along its plane; wherein one side of the rectangle facing to the hollow rectangular steel column is firmly attached to a rectangular cylinder by welding; wherein another side of the rectangle facing to the right rising portion which is one of the sides rising from the U-shaped receiving member is firmly attached to the right rising portion by welding; wherein still another of the rectangle facing to the left rising portion which is the other side rising from the U-shaped receiving member is firmly attached to the left rising portion by welding; wherein the remaining one side of the rectangle facing to the upper surface of the hollow rectangular steel beam is firmly attached to the hollow rectangular steel beam; and wherein the lid is formed with slits, and the lid is firmly attached to the hollow rectangular steel beam via the slits.

[0014] According to the invention claimed in claim 6, in the joint structure of iron framework claimed in claims 1 to 5, a reinforcing member is provided to traverse the hollow rectangular steel column along its longitudinal direction.

[0015] According to the invention claimed in claim 7, in the joint structure of iron framework claimed in claims 1 to 5, a reinforcing member is provided to traverse the hollow rectangular steel beam along its longitudinal direction.

[0016] According to the invention claimed in claim 8, in the joint structure of iron framework claimed in claims 1 to 5, a reinforcing member is provided to traverse the hollow rectangular steel beam along its longitudinal direction.

[0017] According to the invention claimed in claim 9, in the joint structure of iron framework claimed in claims 1 to 5, a plurality of reinforcing members are provided to traverse the hollow rectangular steel beam in its longitudinal direction, and a grout material is injected in a space between the reinforcing members.

[0018] According to the invention claimed in claim 10, in the joint structure of iron framework claimed in claims 1 to 5, the U-shaped receiving member includes: an L-shaped receiving member without either one of the right rising portion and the left rising portion rising from the bottom portion; and a flat-shaped member connected to the bottom portion of the L-shaped receiving member by welding at a position having no rising portion so as to form a U shape in cross section.

[0019] According to the invention claimed in claim 11, a coupling member includes: a rectangular cylinder fitted to an outer periphery of a hollow rectangular steel column and firmly attached to a hollow rectangular steel column; a U-shaped receiving member provided to a side surface of the rectangular cylinder, the U-shaped receiving member having a bottom portion protruded from the side surface of the rectangular cylinder, having a U-shaped opening portion located to face upward, having a U-shaped end surface firmly attached to the side surface of the rectangular cylinder; and a lid firmly attached to the U-shaped receiving member in a state of covering the upper surface of the hollow rectangular steel beam mounted in the U-shaped receiving member.

[0020] According to the joint structure of iron framework claimed in claim 1, it is not needed to cut some midpoint of the hollow rectangular steel column as in the prior arts. Instead, the rectangular cylinder of the coupling member is fitted to the outer periphery of the hollow rectangular steel column and is firmly attached to the hollow rectangular steel column. As a result, the workability is enhanced. In addition, since the beam is a hollow rectangular steel beam unlike a conventional beam having a H-shaped cross section, the joint structure produces an advantage that the strength against the lateral loading is increased.

[0021] Further, according to the joint structure of iron framework claimed in claim 2, in addition to the advantage of the invention claimed in claim 1 the following advantage is produced. That is, the side surface of the rectangular cylinder is formed with a slit and the rectangular cylinder is firmly attached to the hollow rectangular steel column via the slit. Thus, the rectangular cylinder can be firmly attached to the hollow rectangular steel column easily and strongly

[0022] The strength can be adjusted by changing the length, width, and the like of each slit, or by providing a plurality of slits.

[0023] Further, according to the joint structure of iron framework claimed in claim 3, in addition to the advantage of the invention claimed in claim 1, the following advantage is produced. That is, the upper surface of the hollow rectangular steel beam is formed with a hand insertion hole of a size that allows a hand to enter therein. Thus, the U-shaped receiving member and the hollow rectangular steel beam are easily connected to each other by the bottom bolt and the bottom nut via the bottom bolt hole and the bottom surface bolt hole, by the left bolt and the left nut via the right bolt hole and the right side surface bolt hole, and by the right bolt and the right nut via the right bolt and the right side surface bolt.

[0024] Further, according to the joint structure of iron framework claimed in claim 4, in addition to the advantage of the invention claimed in claim 1 described above, the following advantage is produced. That is, when the height of the side surface of the hollow rectangular steel beam is large, the left side surface of the hollow rectangular steel beam is formed with a hand insertion hole of rectangular beam's left side surface of a size that allows a hand to enter therein. At the same time, the right side surface of the hollow rectangular steel beam is formed with a hand insertion hole of rectangular beam's right side surface of a size that allows a hand to enter therein. The U-shaped receiving member and the hollow rectangular can be easily connected to each other by the left bolt and the left nut via the left bolt hole and left side surface bolt hole, and by the right bolt and the right nut via the right bolt hole and the right side surface bolt hole. As a result, the workability can be enhanced.

[0025] Further, according to the joint structure of iron framework claimed in claim 5, in addition to the advantage of the invention claimed in claim 1 above, the following advantage is produced. That is, since the lid is formed with a slit and the lid is firmly attached to the hollow rectangular steel beam via the slit, the lid can be firmly attached to the hollowing rectangular steel beam easily and strongly.

[0026] The strength can be adjusted by changing the length, width, and the like of each slit, or by providing a plurality of slits.

[0027] Further, according to the joint member for connecting a rectangular steel beam to a rectangular steel column claimed in claim 11, the rectangular cylinder of the joint member is fitted to the outer periphery of the hollow rectangular steel column and is firmly attached to the hollow rectangular steel column without cutting some midpoint of the hollow rectangular steel column as in prior arts. As a result, the workability is enhanced. In addition, since the beam is a hollow rectangular steel beam unlike a conventional beam having a H-shaped cross section, the joint member produces an advantage that the strength against the lateral loading is increased.

[0028] FIG. 1 is a schematic perspective view of an iron framework structure using the joint structure of iron framework according to an embodiment of the present invention.

[0029] FIG. 2 is a schematic perspective view showing a state before the joint structure of iron framework shown in FIG. 1 is assembled, where the coupling member is in a state before being fitted to a hollow rectangular steel column.

[0030] FIG. 3 is a schematic perspective view showing a state where the coupling member shown in FIG. 2 is firmly attached to a hollow rectangular steel column and a hollow rectangular steel beam is before being connected.

[0031] FIG. 4 is a schematic perspective view showing a state where a hollow rectangular steel beam is placed to a bottom portion of the coupling member shown in FIG. 3 and the upper surface of the hollow rectangular steel beam is before being covered with a lid.

[0032] FIG. 5 is a schematic perspective view showing a state where a lid is placed to cover the upper surface of a hollow rectangular steel beam shown in FIG. 4 and the lid and the upper surface are connected with each other by welding.

[0033] FIG. 6 is a schematic cross-sectional view along the line 6-6 of FIG. 5.

[0034] FIG. 7 is a schematic cross-sectional view along the line 7-7 of FIG. 6.

[0035] FIG. 8 is a schematic frontal cross-sectional view of the hollow rectangular steel column which is apart of the joint structure of iron framework shown in FIG. 1.

[0036] FIG. 9 is a schematic cross-sectional view of the rectangular steel column (or the hollow rectangular steel beam) in a state before a reinforcing material (knot material) is inserted into the hollow rectangular steel (or the hollow rectangular steel beam) shown in FIG. 4.

[0037] FIG. 10 is a schematic cross-sectional view along the line 10-10 of FIG. 9 where the reinforcing material (knot material) shown in FIG. 9 is inserted into the rectangular steel column (or the hollow rectangular steel beam) and is firmly attached by welding.

[0038] FIG. 11 is a schematic partially enlarged cross-sectional view showing a part of FIG. 10 in an enlarged state.

[0039] FIG. 12 is a schematic partially enlarged cross-sectional view showing a part of FIG. 10 in an enlarged state FIG. 13 is a diagram showing a state where a lateral coupling member is used in the case where the lateral length of the hollow rectangular steel beam shown in FIG. 1 is longer than its longitudinal length, where FIG. 13A is a plan view, FIG. 13B is a frontal view, and FIG. 13C is a bottom view.

[0040] FIG. 14 is a schematic exploded perspective view showing the FIG. 13 in an exploded state.

[0041] FIG. 15 is a schematic perspective view of another embodiment of FIG. 3, and showing a state where the coupling member is firmly attached to the hollow rectangular steel column and the hollow rectangular steel beam is before being connected.

[0042] FIG. 16 is a schematic perspective view showing a state where the hollow rectangular steel beam is placed to the bottom portion of the coupling member shown in FIG. 15 and before and after the lid is placed to cover the upper surface of the hollow rectangular steel beam.

[0043] FIG. 17A is a schematic cross-sectional view along the line 17-17 of FIG. 16, and FIG. 17B is a schematic partially enlarged cross-sectional view.

[0044] FIG. 18 is a schematic frontal view according to another embodiment of FIG. 3, and showing a state where the coupling member is firmly attached to the hollow rectangular steel column and before the hollow rectangular steel beam is connected.

[0045] FIG. 19 is a schematic frontal view according to another embodiment of FIG. 18, and showing a state where the coupling member is firmly attached to the hollow rectangular column and before the hollow rectangular steel beam is connected.

[0046] FIG. 20 is a schematic perspective view showing a state where a hollow rectangular steel beam is placed to the bottom portion of the coupling member shown in FIG. 19 and before the lid is placed to cover the upper surface of the hollow rectangular steel beam.

[0047] A joint structure of iron framework and a coupling member for connecting a rectangular steel beam to a rectangular steel column according to an embodiment of the present invention will be described with reference to drawings.

[0048] A reference numeral 1 shown in FIG. 1 denotes an iron framework structure constituted by connecting a hollow rectangular beam 4 to a hollow rectangular steel column 2 via a coupling member 3.

[0049] An outer shape of a cross-section crossing over a longitudinal direction of the hollow rectangular steel column 2 and an outer shape of a cross-section crossing over a longitudinal direction of the hollow rectangular steel beam 4 respectively assume a rectangular shape.

[0050] The coupling member 3 is used for connecting the hollow rectangular steel beam 4 to the hollow rectangular steel column 2. As shown in FIGS. 2 to 8, the coupling member 3 schematically includes: a rectangular cylinder (substantially rectangular sleeve) 31; U-shaped receiving members 32 each formed on a side surface of the rectangular cylinder (substantially rectangular sleeve); and lids 33 for covering an opening 32a of each U-shaped receiving member 32 and fixedly attached to each receiving member 32 so as to cover the upper surface of the hollow rectangular steel beam 4 mounted in the U-shaped receiving member 32.

[0051] The rectangular cylinder (substantially rectangular sleeve) 31 assumes the shape of rectangular cylinder, and is fitted to the outer periphery of the hollow rectangular steel column 2 and is, firmly attached to the hollow rectangular steel column 2 by welding. The site of the rectangular cylinder 31 fixedly attached by welding has a site (denoted by reference numeral A in FIG. 3) extending around the entire circumference of the upper edge portion of the rectangular cylinder (substantially rectangular sleeve) 31 and fixedly attached by welding to the outer periphery of the hollow rectangular steel column 2; and a site (denoted by reference numeral B in FIG. 3) extending around the entire circumference of the lower edge portion of the rectangular cylinder (substantially rectangular sleeve) 31 and fixedly attached by welding to the outer periphery of the hollow rectangular column 2.

[0052] As shown in FIG. 2, each U-shaped receiving member 32 provided on the side surface of the rectangular cylinder (substantially rectangular sleeve) 31 substantially includes: a U-shaped bottom portion 32b; a right rising portion 32c which is one of the sides rising from the bottom portion 32b; and a left rising portion 32d which is the other side rising from the bottom portion 32b.

[0053] Further, the U-shaped bottom portion 32b is formed with a bottom bolt hole H1 for allowing a bolt to pass therethrough; the right rising portion 32c is formed with a right bolt hole H2 for allowing a bolt to pass therethrough; and the left rising portion 32d is formed with a left bolt hole H3 for allowing a bolt to pass therethrough, respectively.

[0054] As shown in FIG. 2, each U-shaped receiving member 32 is structured as follows. That is, the U-shaped bottom portion 32b extends from the side surface of the rectangular cylinder 31 and the U-shaped opening 32a is directed upward. In addition, the U-shaped end surface of the U-shaped receiving member 32 is fixedly attached to the side surface of the rectangular cylinder and is connected to the hollow rectangular steel beam 4. The reference numeral C shown in FIG. 3 denotes a site of the U-shaped receiving member 32 which is firmly attached by welding to the side surface of the rectangular cylinder 31 along the U-shaped outer periphery of the U-shaped end surface of the U-shaped receiving member 32, that is, not only the side surfaces but also the bottom surface. The U-shaped receiving member 32 shown in FIG. 3 is respectively mounted to the four surfaces of the rectangular cylinder 31, and thus, the U-shaped end surface of the U-shaped receiving member 32 is firmly attached by welding to each of the side surfaces of the rectangular cylinder 31.

[0055] In addition to the welded sites A and B described above, as shown in FIG. 2, the rectangular cylinder 31 is formed with slits at its side surface. The rectangular cylinder 31 is firmly attached by, for example, welding to the hollow rectangular steel column 2 via these slits S. Meantime, the length, width, and the like of each slit S is properly set in consideration of the strength.

[0056] Each slit S of the coupling member 3 shown in FIG. 2 is formed on all of the side surfaces of the rectangular cylinder 31, that is, four surfaces. As shown in FIG. 6, one surface is formed with three slits DDD, and another surface is formed with two slits EE, and still another surface is formed with two slits FF, and still another surface is formed with one slit G. The reference numerals D, E, F, and G shown in FIG. 6 respectively show a site where the rectangular steel column 2 and the rectangular cylinder 31 are firmly attached by welding to each other via the slit S.

[0057] As described above, the coupling member 3 is used for connecting the hollow rectangular steel beam 4 to the hollow rectangular steel column 2 to which the U-shaped receiving members 32 are firmly attached to the side surfaces of the rectangular cylinder 31. As shown in FIGS. 2 and 3, thus-structured coupling member 3 is fitted to the outer periphery of the hollow rectangular steel column 2 and is firmly attached thereto by welding. As described above, in this embodiment, the coupling member 3 is firmly attached to the rectangular cylinder 31 strongly through the welded site A firmly attached to the hollow rectangular steel column 2 over the entire peripheral portion of the rectangular cylinder 31 and the welded site B firmly attached to the hollow rectangular steel column 2 over the entire peripheral portion of the lower edge of the rectangular cylinder 31, in addition to the welded sites D, E, F, G of the slits S.

[0058] After the coupling member 3 is firmly attached to the rectangular cylinder 31, the hollow rectangular steel beam 4 is moved in the direction along the arrow shown in FIG. 3 (or the hollow rectangular steel beam 4 is moved from upward to downward), so that the hollow rectangular steel beam 4 is brought into contact with the bottom portion 32b of the U-shaped receiving member 32 (see FIG. 4).

[0059] The reference numeral 41 in FIGS. 3 and 4 denotes a hand insertion hole formed on the upper surface of the hollow rectangular steel beam 4 for allowing a hand to enter therein. The bottom surface of the hollow rectangular steel beam 4 is formed with a bottom surface bolt hole 42d corresponding to the bottom bolt hole H1 (see FIG. 7); the right surface of the hollow rectangular steel beam 4 is formed with a right surface bolt hole 42f corresponding to the right bolt hole H2 (see FIGS. 6 and 7); and the left surface of the hollow rectangular steel beam 4 is formed with a left surface bolt hole 42g corresponding to the left bolt hole H3 (see FIGS. 6 and 7), respectively.

[0060] Therefore, as shown in FIG. 7, the U-shaped receiving member 32 and the hollow rectangular steel beam 4 are adopted to be connected to each other by the bottom bolt TB and the bottom nut TN via the bottom bolt hole H1 and the bottom surface bolt hole 42d, by the right bolt RB and the right nut RN via the right bolt hole H2 and the right side surface bolt hole 42f, and by the left bolt LB and the left nut LN.

[0061] As described above, since the upper surface of the hollow rectangular steel beam 4 is formed with a hand insertion hole 41 of a size allowing a hand holding a bolt (or a nut) to enter therein, the U-shaped receiving member 32 and the hollow rectangular steel beam 4 can be easily connected to each other by the bottom bolt TB and the bottom nut TN via the bottom bolt hole H1 and the bottom surface bolt hole 42d, by the right bolt RB and the right nut RN via the right bolt hole H2 and the right side surface bolt hole 42f, and by the left bolt LB and the left nut LN via the left bolt hole H3 and the left side surface bolt hole 42g. As a result, the workability can be enhanced.

[0062] Further, as shown in FIGS. 4 and 5, each lid 33 covering the upper surface of the hollow rectangular steel beam 4 is formed with slits. The lid 33 is firmly attached to the hollow rectangular steel beam 4 via the slits ST by, for example, welding. The length, width, and the like of each slit ST are properly determined in consideration of strength. In this embodiment, four slits, two slits, four slits, and six slits are formed in the respective lids 33. The site where the lid 33 is in contact with the hollow rectangular steel column 2, the site where the lid 33 is in contact with the upper end surface of the left rising portion 32c, and the site where the lid 33 is in contact with the left rising portion 32d are also firmly attached by welding.

[0063] Specifically, each lid 33 is in the shape of rectangle when viewed along its plane, and one side of the rectangle facing to the rectangular cylinder 31 is firmly attached to the rectangular cylinder 31 by welding (the welded site is denoted by the reference numeral X1 in FIG. 5). Another side of the rectangle facing to the right rising portion 32c which is one of the sides rising from the bottom portion 32b of the U-shaped receiving member 32 is firmly attached to the right rising portion 32c by welding (the welded site is denoted by the reference numeral X2 in FIG. 5). Still another side of the rectangle facing to the left rising portion 32d which is the other side rising from the bottom portion 32b of the U-shaped receiving member 32 is firmly attached to the left rising portion 32d by welding (the welded site is denoted by the reference numeral X3 in FIG. 5). The remaining one side of the rectangle facing to the upper surface of the hollow rectangular steel beam is firmly attached to the upper surface of the hollow rectangular steel beam 4 (the welded site is denoted by the reference numeral Z4 in FIG. 5). Further, each lid 33 is firmly attached to the upper surface of the hollow rectangular steel beam 2 (the welded site is denoted by the reference numeral X5 in FIG. 5).

[0064] Further, as shown in FIGS. 3 and 8 to 12, a reinforcing materials (knot materials) 20 are inserted into the hollow rectangular steel column 2 (the length of the rectangular steel column is 25 m for example) via an inserting hole 2a at specified intervals (for example, 1 m) so as to traverse the longitudinal direction of the hollow rectangular steel column 2 in order to increase resistance. The reinforcing materials are firmly attached to the hollow rectangular steel column 2 via the inserting hole 2 and other inserting holes 2b, 2c, and 2d. Each site firmly attached by welding is denoted by the reference numeral Y.

[0065] As shown in FIGS. 9 to 12, at the time of welding, the welding can be performed without using a backing ring. Into the hollow rectangular steel column 2, an unillustrated concrete material (grout material) may be injected. A space between the adjacent reinforcing materials (knot materials) 20 is filled with an unillstrated concrete material (grout material) via a hole 20a formed at the center of each reinforcing material (knot material) 20.

[0066] Specifically, the injection of the concrete (grout material) and the like into the hollow rectangular steel column 2 is effective in preventing in-plane buckling from occurring in the hollow rectangular steel column 2 due to the binding force that each reinforcing material (knot material) 20 has. In particular, the resistances to bending moment, shearing force, and axial force applied to the hollow rectangular steel column 2 at the time of earthquake and the like are significantly increased. In addition, the hollow rectangular steel column 2 gains significantly increased resistance to buckling force generated by a vertical loading applied to the hollow rectangular steel column 2. In addition, since the concrete (grout material) and the like are present inside the hollow rectangular steel column 2, the concrete (grout material) and the like are not in contact with the air and thus are free from oxidation. Therefore, the concrete (grout material) and the like maintains its original alkaline nature over a long period of time. Further, the synthesized rigidities of the rectangular steel column 2, the coupling member 3, and the concrete (grout material) and the like significantly increase the stress transmission by the rectangular steel beam 4 at the joint portion.

[0067] If the resistance does not become short, the reinforcing material (knot material) 20 and an unillustrated concrete material (grout material) and the like inside the hollow rectangular steel column 2 may be omitted properly.

[0068] Contrarily, if the resistance of the hollow rectangular steel beam 4 becomes short, a reinforcing material (knot material) 20, an unillustrated concrete (grout material), and the like [an unillustrated concrete (grout material) and the like is not necessarily provided to fill the entire space between the adjacent reinforcing materials (knot materials) 20, but may be provided partially between the space therebetween] may be properly provided inside the hollow rectangular steel beam 4 as is the case of the hollow rectangular steel column 2 [the symbol ( ) in FIGS. 9R and 9 to 12 shows a case where the hollow rectangular steel column 2 is substituted by the hollow rectangular steel beam 4].

[0069] Further, if the lateral length of the hollow rectangular steel beam 4 is longer than its longitudinal length, the lateral coupling member 5 is used for connection (see FIGS. 13 and 14).

[0070] Specifically, the horizontal coupling member 5 is in the shape of rectangular cylinder. The upper surface of the lateral coupling member 5 is formed with hand insertion holes 51, 52 of the sizes allowing a hand to enter therein. The front surface of the lateral coupling member 5 is formed with a front bolt hole 54. The back surface of the coupling member 5 is formed with a back surface bolt hole 55. The bottom surface of the lateral coupling member 5 is formed with a bottom surface bolt hole 56.

[0071] One upper surface of the hollow rectangular steel beam 4 is formed with a beam's hand insertion hole 44 corresponding to the hand insertion hole 52. The front surface of the hollow rectangular steel beam 4 is formed with a beam's front bolt hole 45. The back surface of the hollow rectangular steel beam 4 is formed with a beam's bolt hole 46. The bottom surface of the hollow rectangular steel beam 4 is formed with a beam's bottom surface bolt hole 47.

[0072] The other upper surface of the hollow rectangular steel beam 4 is formed with a beam's hand insertion hole 42 corresponding to a hand insertion hole 51. The front surface of the hollow rectangular steel beam 4 is formed with a beam's front bolt hole 43. The back surface of the hollow rectangular steel beam 4 is formed with a beam's bolt hole (not shown). The bottom surface of the hollow rectangular steel beam 4 is formed with a beam's bottom surface bolt hole (not shown).

[0073] One side of the hollow rectangular steel beam 4 and the other side of the hollow rectangular steel beam 4 are put into the lateral coupling member 5 in such a manner that the beam's hand insertion hole 44 corresponds to the hand insertion hole 52; the beam's front bolt hole 45 corresponds to the front bolt hole 54; the beam's bolt hole 46 corresponds to the back surface bolt hole 55; the beam's bottom surface bolt hole 47 corresponds to the bottom surface bolt hole 56; the beam's hand insertion hole 42 corresponds to the hand insertion hole 51; the beam's front bolt hole 43 corresponds to the front bolt hole 54; the beam's bolt hole (not shown) formed on the back surface at the other side of the hollow rectangular steel beam 4 corresponds to the back surface bolt hole 55; and the beam's bottom surface bolt hole (not shown) formed on the bottom surface of the other hollow rectangular steel beam 4 corresponds to the bottom surface bolt hole 56. Then, bolts (not shown) are engaged with nuts N1, N2, N3 corresponding to the bolts, and one side of the hollow rectangular steel beam 4 and the other side of the hollow rectangular steel beam 4 are connected to each other via the lateral coupling member 5. After that, the connection between one side of the hollow rectangular steel beam 4 and the other side of the hollow rectangular steel beam 4 is made to be strong via the lateral coupling member 5 by welding via a slit 53 and plates F1, F2.

[0074] The plate F1 is of a size that can be accommodated in the hand insertion hole 52. The space between the plate F1 and the hand insertion hole 52 is filled by welding so that the plate F1 and the hand insertion hole 52 are connected with each other. The reference numeral Y1 denotes a site connected by welding. The plate F2 is of a size that can be accommodated in the hand insertion hole 51. The space between the plate F2 and the hand insertion hole 52 is filled by welding so that the plate F2 and the hand insertion hole 51 are connected with each other. The reference numeral Y2 denotes a site connected by welding. The reference numeral Y3 denotes a site connected by welding where the lateral member 5 is connected to the hollow rectangular steel beam 4 via the slit 53.

[0075] In FIGS. 13 and 14, when the lateral length of the hollow rectangular steel beam 4 is longer than its longitudinal length, the connection is made using the lateral coupling member 5 in the shape of rectangular cylinder. However, the present invention is not limited thereto. Although not illustrated, as is the case of the U-shaped receiving member 32 and the lid 33 firmly attached to the U-shaped receiving member 32 described above, the surface having the hole insertion holes 51, 52 and the slit 53 of the lateral coupling member 5 is separated, that is, the surface having the hole insertion holes 51, 52, and the slit 53 is independent from the U-shaped receiving member. Then, the U-shaped receiving member and the surface having the hand insertion holes 51, 52, and the slit 53 may be connected with each other by welding.

[0076] When the height dimension H of the hollow rectangular steel beam 4 is large as shown in FIG. 15, the hand insertion hole 41 formed on the upper surface of the hollow rectangular steel beam 4 shown in FIG. 4 cannot handle with such a beam having large height (in FIGS. 15 to 17, the same portions as described above are denoted by the same reference numerals and the descriptions thereof are partially omitted).

[0077] Specifically, as shown in FIGS. 15 to 17, the left side surface of the hollow rectangular steel beam 4 is formed with a hand insertion hole of rectangular beam's left side surface 4a of a size that allows a hand to enter therein, and the right side surface of the hollow rectangular beam 4 is formed with a hand insertion hole 4b of rectangular beam's right side surface of a size that allows a hand to enter therein (see FIG. 17), respectively.

[0078] A surface of the left rising portion 32d is formed with a hand insertion hole 32d′ of rising portion's left side surface that corresponds to the hand insertion hole 4a of rectangular beam's left side surface. A surface of the right rising portion 32c is formed with a hand insertion hole 32c′ of rising portion's right side surface that corresponds to the hand insertion hole 4b of rectangular beam's right side surface. As is the case of the embodiment shown in FIG. 7, as is shown in FIG. 17A, the U-shaped receiving member 32 and the hollow rectangular steel beam 4 are connected to each other by the bottom bolt TB and the bottom nut TN via the bottom bolt hole H1 and the bottom surface bolt hole 42d, by the right bolt RB and the right-side nut RN via the right bolt hole H1 and the bottom surface bolt hole 42d, and by the left bolt LB and the left nut LN via the left hole H3 and the left side surface bolt hole 42g.

[0079] Further, the upper surface of the hollow rectangular steel beam 4 is covered with the lid 33 shown in FIG. 16. The lid 33 is firmly attached by welding to the hollow rectangular steel beam 4 via the slits ST.

[0080] The hand insertion hole 4a of rectangular beam's left side surface is closed via a plate F2′ located inside the hand insertion hole of rising portion's left side surface 32d′. At the same time, the left rising portion 32d is connected to the hollow rectangular steel beam 4 by welding via the plate F2′ (see FIG. 17B). Similarly, the hand insertion hole 4b of rectangular beam's right side surface is closed via a plate F1′ located inside the hand insertion right rising portion right side surface hole 32c′. At the same time, the right rising portion 32c is connected to the hollow rectangular steel beam 4 by welding via the plate F1′.

[0081] In some cases, it is enough to provide either one of the hand insertion hole 4a of rectangular beam's left side surface and the hand insertion hole 4b of rectangular beam's right side surface. In such cases, the number of the hand insertion hole (4a or 4b) of rectangular beam's side surface is one. The site on the surface of the right rising portion 32c or on the surface of the left rising portion 32d that corresponds to the hand insertion hole of rectangular beam's side surface (4a or 4b) will be a hand insertion hole of rising portion's side surface (32c′ or 32d′).

[0082] Therefore, according to the joint structure of iron framework 1 described above, the rectangular cylinder 31 of the joint member 3 is fitted to the outer periphery of the hollow rectangular steel column and is firmly attached to the hollow rectangular steel column 2 without cutting some midpoint of the hollow rectangular steel column as in prior arts. As a result, the workability is enhanced. In addition, since the beam is a hollow rectangular steel beam 4 unlike a conventional beam having a H-shaped cross section, the strength against the lateral loading is increased.

[0083] The shape of the U-shaped receiving member 32 is not limited to that shown in FIG. 3. Alternatively, for example, as shown in FIG. 18, the U-shaped receiving member 32 may include: a U-shaped bottom portion 32b; a right rising portion 32c which is one of the sides rising from the bottom portion 32b at an angle of 90 degree with respect to the bottom portion 32b; and a left rising portion 32d which is the other side rising from the bottom portion 32b at an angel exceeding 90 degree [90 degree+θ] with respect to the bottom portion 32b. In FIG. 18, the reference numeral C′ denotes the welded site where the rectangular cylinder 31 and the U-shaped receiving member 32 are connected to each other by welding. The hollow rectangular steel beam 4 is lifted down to be in contact with the U-shaped receiving member 32.

[0084] The U-shaped receiving member 32 is not limited to that shown in FIG. 18. Alternatively, for example, as shown in FIGS. 19 and 20, the U-shaped receiving member 32 may include: an L-shaped receiving member 32′ which has only one of the right rising portion 32c and the left rising portion 32d which rise from the bottom portion 32b (in this embodiment, there is no left rising portion 32d); and a flat plane-shaped member 32′d welded to the bottom portion 32b of the L-shaped receiving member 32′ (the welded site is denoted by the reference numeral G in FIG. 20) at a site where there is no rising portion (in this embodiment, a left rising portion 32d). In FIG. 19, the hollow rectangular steel beam 4 is lifted down to be in contact with the U-shaped receiving member 32. The reference numeral H₁⁵ denotes a bottom bolt hole, H₂⁵ a right bolt hole, and H₃⁵ a left bolt hole.