JP6750555B2

JP6750555B2 - Non-diaphragm type beam-column joint structure

Info

Publication number: JP6750555B2
Application number: JP2017085933A
Authority: JP
Inventors: 中川　佳; 佳中川; 匠石井
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2017-04-25
Filing date: 2017-04-25
Publication date: 2020-09-02
Anticipated expiration: 2037-04-25
Also published as: JP2018184742A

Description

本発明は、外力が加わった場合における柱溶接部の破断を防止することのできるノンダイアフラム型の柱梁接合構造体に関する。 The present invention relates to a non-diaphragm type column-beam joint structure capable of preventing breakage of a column welded portion when an external force is applied.

ダイアフラム（例えば、外ダイアフラム、内ダイアフラム、及び通しダイアフラム等）を用いずに柱と梁とが接合された柱梁接合構造体（仕口構造体）として、ノンダイアフラム型の柱梁接合構造体（ノンダイアフラム仕口）が知られている。ノンダイアフラム仕口では、上下に分かれた柱と柱との間に仕口用鋼管を介在させ、仕口用鋼管の側面に梁を取り付ける。柱と仕口用鋼管、及び仕口用鋼管と梁とは、それぞれ溶接により接合される。 A non-diaphragm type column-beam joint structure (portion structure) in which a column and a beam are joined without using a diaphragm (for example, an outer diaphragm, an inner diaphragm, and a through diaphragm) Non-diaphragm connection) is known. In the non-diaphragm joint, a steel pipe for connection is interposed between a column that is divided into upper and lower columns, and a beam is attached to the side surface of the steel pipe for connection. The column and the steel pipe for connection, and the steel pipe for connection and the beam are respectively joined by welding.

ノンダイアフラム仕口は、ダイアフラムを用いた仕口構造体に比べて、溶接線の低減によりコストを削減できたり、梁の取付自由度を拡大できたりするといった利点がある。一方、ノンダイアフラム仕口では、ダイアフラムを用いていないことから、梁のフランジ部が取り付く箇所において仕口用鋼管の管壁の面外変形に起因する局部変形が起こりやすいという問題がある。この局部変形に関しては、従来多くの研究が行われている。 The non-diaphragm joint has an advantage over the joint structure using the diaphragm in that the welding line can be reduced in cost and the beam can be attached more freely. On the other hand, in the non-diaphragm joint, since no diaphragm is used, there is a problem that local deformation is likely to occur due to out-of-plane deformation of the pipe wall of the steel pipe for joint, at the position where the flange portion of the beam is attached. Many studies have been conducted on this local deformation.

非特許文献１では、降伏線理論から導いた局部変形の耐力式が提案され、実験で求めた耐力と耐力式を用いた計算結果とが良好に整合することが報告されている。本知見をもとに、非特許文献２では、梁が取り付く仕口用鋼管の板厚を柱の板厚よりも増厚することで、所要の耐力、剛性を実現したノンダイアフラム仕口が提案されている。これらの研究成果は、非特許文献３に反映され、現在、ノンダイアフラム仕口は広く利用可能な構造となっている。 Non-Patent Document 1 proposes a proof formula of local deformation derived from the yield line theory, and reports that the proof stress obtained by experiments and the calculation result using the proof formula are well matched. Based on this finding, Non-Patent Document 2 proposes a non-diaphragm joint that achieves the required yield strength and rigidity by increasing the plate thickness of the steel pipe for connection to which the beam is attached to be greater than the plate thickness of the column. Has been done. The results of these studies are reflected in Non-Patent Document 3, and at present, the non-diaphragm joint has a widely usable structure.

上記のように、ノンダイアフラム仕口においては、仕口用鋼管の局部変形を抑えるために、仕口用鋼管の板厚を増厚することが広く行われている。 As described above, in the non-diaphragm joint, it is widely practiced to increase the plate thickness of the joint steel pipe in order to suppress local deformation of the joint steel pipe.

森田耕次、他：箱形断面柱−Ｈ形断面はり接合部のダイアフラム補強に関する研究、日本建築学会構造系論文報告集,p100-110, 1988Koji Morita, et al.: Study on diaphragm reinforcement of beam-column joints with box-shaped cross-section, H-shaped cross-section, Proceedings of Architectural Institute of Japan, p100-110, 1988 村上行夫、他：増厚補強型柱・梁接合部を用いた半剛接架構設計法に関する研究、鋼構造論文集、第１巻４号、１９９４．１２Yukio Murakami, et al.: Study on Semi-rigid Frame Design Method Using Thickened Reinforced Column-Beam Joints, Steel Structures, Vol. 1, No. 4, 1994.12. 日本建築学会、鋼構造接合部設計指針、２０１２．３Architectural Institute of Japan, Steel structure joint design guideline, 2012.3.

特開２０１０−２４２２９０JP, 2010-242290, A 特開２００７−１４６５６５JP 2007-146565A

一方で、ノンダイアフラム仕口においては、柱と仕口用鋼管との間における柱溶接部における靭性や強度が、柱や仕口用鋼管の母材の靭性や強度と比較して劣る。よって、例えば図５に示すように（詳細については後述する）、ノンダイアフラム仕口において最初に柱が降伏するパターンの場合に、溶接部の降伏及び脆性破壊（破断）が先行し、仕口構造体の崩壊を招きやすいという問題があることが見出された。建築物は、外力を加えられた際に損傷は受けても崩壊しないことが重要であり、ノンダイアフラム仕口においても構造体の崩壊を防止することが求められる。 On the other hand, in the non-diaphragm joint, the toughness and strength at the column welded portion between the column and the joint steel pipe are inferior to the toughness and strength of the base material of the column and the joint steel pipe. Therefore, for example, as shown in FIG. 5 (details will be described later), in the case of a pattern in which a column yields first in a non-diaphragm joint, yielding and brittle fracture (breakage) of the weld portion precede, and the joint structure It has been found that there is a problem that it tends to cause body collapse. It is important that a building does not collapse even if it receives damage when external force is applied, and it is required to prevent the collapse of the structure even in the non-diaphragm joint.

以下、ノンダイアフラム仕口における溶接部に関わる特許文献を概観する。 Hereinafter, the patent documents relating to the welded portion in the non-diaphragm joint will be reviewed.

特許文献１では、梁フランジの取付に関して、裏当て金の形状を工夫することにより、健全な梁フランジ溶接部を得る方法が提案されている。しかし、特許文献１では、柱と仕口用鋼管との溶接部を健全に得る方法については言及されていない。 Patent Document 1 proposes a method for obtaining a sound beam flange welded portion by devising the shape of the backing plate for attaching the beam flange. However, Patent Document 1 does not mention a method for obtaining a welded portion between a column and a steel pipe for connection soundly.

特許文献２では、ノンダイアフラム仕口に梁を偏心させて取り付ける場合の耐力計算式が提案されている。特許文献２の図２によれば、柱と仕口用鋼管との間には溶接部が存在せず、製造コストが高い高周波誘導加熱法を用いて柱と仕口用鋼管とを接続しているものと推察される。 Patent Document 2 proposes a yield strength calculation formula in the case where a beam is eccentrically attached to a non-diaphragm joint. According to FIG. 2 of Patent Document 2, there is no welded portion between the column and the steel pipe for connection, and the column and the steel pipe for connection are connected by using the high frequency induction heating method which is high in manufacturing cost. It is presumed that it is present.

以上のように、従来技術では、柱と仕口用鋼管との間における溶接部として通常の溶接方法を適用することが想定されており、いずれも柱溶接部を起点とした構造体の崩壊を招きやすいという問題点を内包している。 As described above, in the conventional technology, it is assumed that a normal welding method is applied as a welded portion between a column and a steel pipe for connection, and in both cases, collapse of the structure starting from the column welded portion is caused. The problem is that it is easy to invite.

本発明は上記の問題点に鑑みて完成されたものであり、外部から力を加えられた際に、柱溶接部における破断が先行することを回避し、塑性変形能力及び安全性に優れたノンダイアフラム型の柱梁接合構造体を提供することを課題とする。 The present invention has been completed in view of the above problems, when a force is applied from the outside, avoids prior breakage in the column welded portion, and is excellent in plastic deformation capacity and safety. An object is to provide a diaphragm-type column-beam joint structure.

本発明の手段は、以下の通りである。
［１］上下に分かれた柱と、前記柱の端面に接続される仕口用鋼管と、前記仕口用鋼管の側面に接合される梁と、を有するノンダイアフラム型の柱梁接合構造体であって、前記柱と前記仕口用鋼管とは柱溶接部により接合され、前記仕口用鋼管は、前記柱の板厚以上となる板厚を備えた増厚部と、前記増厚部よりも小さい板厚を備えた減厚部と、を有し、前記減厚部と前記柱溶接部とは、以下の式（１）を満たすノンダイアフラム型の柱梁接合構造体。
ｐＺｐ×ｐσｙ≦ｃＺｐ×ｗσｙ・・・（１）
ｐＺｐ：前記減厚部における仕口用鋼管の塑性断面係数（ｍｍ^３）
ｐσｙ：仕口用鋼管を形成する材料の降伏耐力（Ｎ／ｍｍ^２）
ｃＺｐ：前記柱の塑性断面係数（ｍｍ^３）
ｗσｙ：溶接材料の降伏耐力（Ｎ／ｍｍ^２）
［２］前記減厚部は、仕口用鋼管と梁との接続部の上端部及び下端部から、柱軸方向にｂｃ／２以上離れた位置に設けられる［１］に記載のノンダイアフラム型の柱梁接合構造体。但し、ｂｃは、前記仕口用鋼管の縦断面における増厚部同士の距離とする。 The means of the present invention are as follows.
[1] A non-diaphragm type column-beam joint structure having vertically separated columns, a connection steel pipe connected to end faces of the columns, and a beam joined to a side surface of the connection steel pipe There, the column and the steel pipe for connection is joined by a column welded portion, the steel pipe for connection is a thickened portion having a plate thickness equal to or more than the plate thickness of the column, and from the thickened portion. And a reduced thickness portion having a smaller plate thickness, wherein the reduced thickness portion and the column welded portion are non-diaphragm type beam-column joint structures.
pZp×pσy≦cZp×wσy (1)
pZp: Plastic section modulus (mm ³ ) of the steel pipe for connection in the reduced thickness portion
pσy: Yield proof strength (N/mm ² ) of the material forming the steel pipe for connection
cZp: Plastic section modulus of the column (mm ³ )
wσy: Yield strength of welding material (N/mm ² ).
[2] The non-diaphragm type according to [1], wherein the reduced thickness portion is provided at a position bc/2 or more away from the upper end portion and the lower end portion of the connection portion between the steel pipe for connection and the beam in the column axis direction. Beam-column joint structure. However, bc is the distance between the thickened portions in the vertical cross section of the steel pipe for connection.

本発明では、柱降伏型の降伏パターンとなった際であっても、柱と仕口用鋼管とを接合する柱溶接部の破断を防止することができる。 According to the present invention, it is possible to prevent breakage of a column welded portion that joins a column and a steel pipe for a connection even when a column yield type yielding pattern is formed.

図１は、本発明に係るノンダイアフラム型の柱梁接合構造体を正面側から見た部分断面図である。FIG. 1 is a partial cross-sectional view of a non-diaphragm type column-beam joint structure according to the present invention viewed from the front side. 図２は、本発明に係るノンダイアフラム型の柱梁接合構造体を右側面側から見た部分断面図である。FIG. 2 is a partial cross-sectional view of a non-diaphragm type column-beam joint structure according to the present invention as viewed from the right side surface side. 図３は、地震発生時に、柱及び梁に発生する力を示す模式図である。FIG. 3 is a schematic diagram showing forces generated on columns and beams when an earthquake occurs. 図４は、地震発生時に、柱及び梁に発生する力を示す模式図であり、図３の破線部において発生する力の方向をより詳細に説明した図である。FIG. 4 is a schematic diagram showing forces generated on columns and beams when an earthquake occurs, and is a diagram illustrating in more detail the direction of forces generated at the broken line portion of FIG. 図５は、ノンダイアフラム仕口における柱降伏型の降伏パターンを示す模式図である。FIG. 5 is a schematic diagram showing a column yield type yield pattern in a non-diaphragm joint. 図６は、ノンダイアフラム仕口における梁降伏型の降伏パターンを示す模式図である。FIG. 6 is a schematic diagram showing a beam yield type yield pattern in a non-diaphragm joint. 図７は、ノンダイアフラム仕口におけるパネル降伏型の降伏パターンを示す模式図である。FIG. 7 is a schematic diagram showing a panel yield type yield pattern in a non-diaphragm joint. 図８は、ノンダイアフラム仕口における局部降伏型の降伏パターンを示す模式図である。FIG. 8 is a schematic diagram showing a local yield type yield pattern in a non-diaphragm joint.

まず、図１及び図２を用いて、本発明に係るノンダイアフラム型の柱梁接合構造体（以下、単に「柱梁接合構造体」と称することもある。）について説明する。 First, a non-diaphragm type post-beam joint structure (hereinafter, also simply referred to as “post-beam joint structure”) according to the present invention will be described with reference to FIGS. 1 and 2.

図１には柱梁接合構造体を正面から見た図を示し、図２には柱梁接合構造体を右側面から見た図を示す。図１及び２ともに、柱４及び仕口用鋼管１の板厚方向の断面を示す、部分断面図である。 FIG. 1 shows a front view of the beam-column joint structure, and FIG. 2 shows a view of the beam-column joint structure from the right side. 1 and 2 are partial cross-sectional views showing cross sections in the plate thickness direction of a column 4 and a steel pipe 1 for connection.

図１に示すようにノンダイアフラム型の柱梁接合構造体では、上下２つに分かれた柱４の間に仕口用鋼管１が介在する。仕口用鋼管１は、その柱軸方向（上下方向）の両端面において上下の柱４と接合されるとともに、その外側面に梁６が取り付けられる。図２の例で、梁６としてはＨ形鋼が用いられている。 As shown in FIG. 1, in a non-diaphragm type column-beam joint structure, a steel pipe 1 for connection is interposed between two columns 4 which are vertically divided. The steel pipe 1 for connection is joined to the upper and lower columns 4 at both end faces in the column axial direction (vertical direction), and the beams 6 are attached to the outer side faces thereof. In the example of FIG. 2, H-section steel is used as the beam 6.

仕口用鋼管１は梁６を通して伝えられる水平力に耐える必要があることから、仕口用鋼管１のうち梁６が取り付けられている範囲の板厚（ｔｐ）は、柱４の板厚（ｔｃ）よりも大きくすることが好ましい。尚、仕口用鋼管１の板厚（ｔｐ）を増厚しなくとも、局部耐力（図８の符号７）≧梁耐力（図６の符号７）、パネル耐力（図７の符号７）≧梁耐力（図６の符号７）となって、所要の耐力が得られる場合もあるので、ｔｐ≧ｔｃとすればよい。 Since the steel pipe for connection 1 needs to withstand the horizontal force transmitted through the beam 6, the plate thickness (tp) in the range where the beam 6 is attached in the steel pipe for connection 1 is the plate thickness of the column 4 ( It is preferably larger than tc). Even if the plate thickness (tp) of the steel pipe for connection 1 is not increased, the local proof stress (7 in FIG. 8)≧beam proof stress (7 in FIG. 6), panel proof stress (7 in FIG. 7)≧ Since the beam proof strength (reference numeral 7 in FIG. 6) may be obtained and the required proof strength may be obtained, tp≧tc may be set.

図１における右上の吹き出し拡大図では、上側の柱４と仕口用鋼管１とが、裏当て金５及び柱溶接部３を介して接合される態様を示す。裏当て金５は、柱４の内周面と仕口用鋼管１の端面に接続される。柱溶接部３は、裏当て金５と柱４の端面と仕口用鋼管１の端面とによって形成される空間に溶融、固化されてなる溶接材料によって形成される。 The blow-up enlarged view in the upper right of FIG. 1 shows a mode in which the upper column 4 and the steel pipe 1 for connection are joined via the backing metal 5 and the column welded portion 3. The backing plate 5 is connected to the inner peripheral surface of the column 4 and the end surface of the steel pipe 1 for connection. The column welded portion 3 is formed of a welding material that is melted and solidified in a space formed by the backing metal 5, the end surface of the column 4 and the end surface of the steel pipe 1 for connection.

地震発生時において、柱４と梁６とで組み立てられた構造骨組に加えられる力を模式的に示したのが図３及び図４である。図３の破線部において発生する力の向きをより詳細に説明したのが図４である。図４のように、柱４の上部には地震により水平力７が発生し、柱４の下部には当該水平力７とは反対方向に反力８が発生する。また、梁６の左側には地震により下方向への垂直力９が発生し、梁６の右側には当該垂直力９とは反対方向に反力１０が発生する。 3 and 4 schematically show the force applied to the structural frame assembled by the columns 4 and the beams 6 when an earthquake occurs. FIG. 4 illustrates the direction of the force generated in the broken line portion of FIG. 3 in more detail. As shown in FIG. 4, a horizontal force 7 is generated in the upper part of the column 4 due to the earthquake, and a reaction force 8 is generated in the lower part of the column 4 in a direction opposite to the horizontal force 7. Further, a vertical force 9 is generated downward on the left side of the beam 6 due to the earthquake, and a reaction force 10 is generated on the right side of the beam 6 in a direction opposite to the vertical force 9.

このように構造骨組に力が加えられた際に、いずれの部材が最初に降伏するかによって、４つの降伏パターンに分けられる。具体的には、図５に示すように柱４が最初に降伏する柱降伏型、図６に示すように梁６が最初に降伏する梁降伏型、図７に示すように仕口用鋼管１が最初に降伏するパネル降伏型、及び図８に示すように仕口用鋼管１のうち梁６のフランジが取り付いている部分の周囲、すなわち局部が最初に降伏する局部降伏型の４つが挙げられる。 In this way, when a force is applied to the structural frame, it is divided into four yield patterns depending on which member yields first. Specifically, as shown in FIG. 5, a column yielding type in which the column 4 yields first, a beam yielding type in which the beam 6 yields first as shown in FIG. 6, and a joint steel pipe 1 as shown in FIG. There are four types: a panel yielding type in which the first yields, and a local yielding type in which the local yields first, that is, around the portion where the flange of the beam 6 is attached in the steel pipe for connection 1 as shown in FIG. ..

上記の４つの降伏パターンのうち、柱降伏型となるように構造骨組を設計した場合には、強度に劣る柱溶接部３（図５には図示せず）が最初に降伏する可能性が高い。柱溶接部３は、その靱性が低いことから、柱溶接部３が降伏するとまもなく脆性破壊、破断が起きてしまう。柱溶接部３の破断は構造骨組の崩壊に直結してしまう危険性があり、外力が加わった際の崩壊を防ぐことが求められる建築物において大きな問題となる。そこで本発明を適用することにより、柱降伏型の構造骨組であっても柱溶接部３の破断を防止することができ、安全性に優れた柱梁接合構造体が得られる。尚、柱降伏型以外の降伏パターンで設計された構造骨組であっても、本発明を適用することで、柱溶接部３が降伏、破断する可能性を小さくし、より建築物の安全性を向上させることができる。 When the structural frame is designed to be a column yield type among the above four yield patterns, the column welded portion 3 (not shown in FIG. 5) having poor strength is likely to yield first. .. Since the column welded portion 3 has low toughness, brittle fracture and fracture will occur soon after the column welded portion 3 yields. The breakage of the column welded portion 3 has a risk of being directly connected to the collapse of the structural frame, which is a serious problem in a building where it is required to prevent the collapse when an external force is applied. Therefore, by applying the present invention, it is possible to prevent breakage of the column welded portion 3 even in a column yield type structural frame, and to obtain a column-beam joint structure excellent in safety. Even if the structural frame is designed with a yield pattern other than the column yield type, by applying the present invention, the possibility that the column welded portion 3 will yield or break is reduced, and the safety of the building can be further improved. Can be improved.

本発明では、図１に示すように仕口用鋼管１の上端及び下端において、増厚部１ａよりも板厚を減じた減厚部１ｂを設ける。増厚部１ａは、仕口用鋼管１のうち柱４の板厚（ｔｃ）以上の板厚（ｔｐ）を有している部分をいう。減厚部１ｂの板厚は、増厚部１ａの板厚（ｔｐ）よりも薄ければよく、柱４の板厚（ｔｃ）以下であってもよいし、柱４の板厚（ｔｃ）よりも厚くてもよい。 In the present invention, as shown in FIG. 1, at the upper end and the lower end of the steel pipe 1 for connection, a reduced thickness portion 1b having a thickness smaller than that of the increased thickness portion 1a is provided. The thickened portion 1a is a portion of the steel pipe for connection 1 having a plate thickness (tp) equal to or larger than the plate thickness (tc) of the column 4. The thickness of the reduced thickness portion 1b may be smaller than the thickness of the thickened portion 1a (tp), and may be equal to or less than the thickness of the pillar 4 (tc), or the thickness of the pillar 4 (tc). It may be thicker than.

減厚部１ｂを設ける際には、柱溶接部３との関係において以下の式（１）を満たすようにする。
ｐＺｐ×ｐσｙ≦ｃＺｐ×ｗσｙ・・・（１）
ｐＺｐ：減厚部１ｂにおける仕口用鋼管１の塑性断面係数［ｍｍ^３］
ｐσｙ：仕口用鋼管１を形成する材料の降伏耐力［Ｎ／ｍｍ^２］
ｃＺｐ：柱４の塑性断面係数［ｍｍ^３］
ｗσｙ：柱溶接部（溶接材料）３の降伏耐力［Ｎ／ｍｍ^２］ When providing the reduced thickness portion 1b, the following expression (1) is satisfied in relation to the column welded portion 3.
pZp×pσy≦cZp×wσy (1)
pZp: Plastic section modulus [mm ³ ] of the steel pipe 1 for connection in the reduced thickness portion 1b
pσy: Yield proof strength of the material forming the steel pipe 1 [N/mm ² ]
cZp: Plastic section modulus of column 4 [mm ³ ]
wσy: Yield strength of column welded part (welding material) 3 [N/mm ² ]

上記の式（１）によって、（仕口用鋼管の減厚部断面における全塑性モーメント）≦（柱溶接部断面の全塑性モーメント）という関係が満たされる。つまり、図３及び図４で示すように外力が柱梁接合構造体に加わった際に、柱溶接部３よりも先に減厚部１ｂが降伏することになる。柱溶接部３よりも相対的に靭性等の強度が高い仕口用鋼管１の母材の塑性化が先行することにより、柱溶接部３が破断することを防止することができる。 The above formula (1) satisfies the relationship of (total plastic moment in cross section of reduced thickness portion of steel pipe for connection) ≤ (total plastic moment in cross section of column welded portion). In other words, as shown in FIGS. 3 and 4, when the external force is applied to the beam-column joint structure, the reduced thickness portion 1b yields before the column welded portion 3. It is possible to prevent the column welded portion 3 from breaking due to the plasticization of the base material of the steel pipe for connection 1 having a higher strength such as toughness than the column welded portion 3 prior to the plasticization.

前記式（１）を満たすためには、減厚部１ｂの位置、大きさ、形状、仕口用鋼管１の素材の強度等を調節することができる。例えば、前述した「仕口用鋼管の減厚部断面における全塑性モーメント」を小さくするには、減厚部１ｂの板厚を小さくすること、減厚部１ｂにおいて鋼管の外側を減厚すること等を行うことが有効である。また「仕口用鋼管の減厚部断面における全塑性モーメント」を大きくするには、上記と逆の操作を行えばよい。尚、減厚部１ｂは、仕口用鋼管１の全周に亘って設けられていてもよいし、周方向の一部のみに設けられていてもよい。 In order to satisfy the above formula (1), the position, size and shape of the reduced thickness portion 1b, the strength of the material of the steel pipe 1 for connection, etc. can be adjusted. For example, in order to reduce the above-mentioned "total plastic moment in the cross section of the reduced thickness portion of the steel pipe for connection", the plate thickness of the reduced thickness portion 1b should be reduced, and the outside of the steel pipe should be reduced in the reduced thickness portion 1b. Etc. is effective. Further, in order to increase the "total plastic moment in the cross section of the reduced thickness portion of the steel pipe for connection", the reverse operation to the above may be performed. The reduced-thickness portion 1b may be provided over the entire circumference of the connection steel pipe 1, or may be provided only in a part in the circumferential direction.

また、柱のモーメント分布を考えると、柱の階高中央付近の反曲点位置から梁フランジに近づくにつれてモーメントが大きくなることから、減厚部１ｂの位置を仕口用鋼管１の中で梁６のフランジ部６ａ、６ｃに近づけると、よりいっそう、柱溶接部３よりも減厚部１ｂの塑性化を先行させることができる。 Further, considering the moment distribution of the column, the moment increases as the position approaches the beam flange from the inflection point position near the center of the floor height of the column. When the flange portions 6a and 6c of 6 are brought closer to each other, plasticization of the reduced-thickness portion 1b can be more advanced than that of the column welded portion 3.

仕口用鋼管１の上端面側及び下端面側にそれぞれ設けられた溶接部３の破断を防止するように、仕口用鋼管１の上側及び下側にそれぞれ１箇所ずつ減厚部１ｂを設けることが好ましい。この場合、上側の減厚部１ｂと上側の柱溶接部３との間で上述の式（１）を満たすようにし、且つ下側の減厚部１ｂと下側の柱溶接部３との間で上述の式（１）を満たすようにする。 In order to prevent breakage of the welded portions 3 provided on the upper end surface side and the lower end surface side of the connection steel pipe 1, respectively, one thinned portion 1b is provided on each of the upper side and the lower side of the connection steel pipe 1. It is preferable. In this case, the above formula (1) is satisfied between the upper reduced thickness portion 1b and the upper column welded portion 3, and between the lower reduced thickness portion 1b and the lower column welded portion 3. Then, the above equation (1) is satisfied.

本発明の効果を奏する限りにおいて減厚部１ｂの形状は特に制限されないが、減厚部１ｂの成形が容易であること等を鑑みると、減厚部１ｂを曲面状とすることが好ましい。 The shape of the reduced-thickness portion 1b is not particularly limited as long as the effects of the present invention are exhibited, but it is preferable to make the reduced-thickness portion 1b into a curved shape in view of easy molding of the reduced-thickness portion 1b.

減厚部１ｂにおいては、仕口用鋼管１の内側面を減肉してもよいし、外側面を減肉してもよい。急激に仕口用鋼管１の断面形状を変化させると、ひずみ集中による早期破壊が引き起こされることがあるので、曲率半径が５０ｍｍ以上となるように緩やかな減肉加工を行うことが望ましい。 In the reduced thickness portion 1b, the inner side surface of the connection steel pipe 1 may be thinned or the outer side surface may be thinned. If the cross-sectional shape of the steel pipe 1 for connection is suddenly changed, early fracture due to strain concentration may be caused. Therefore, it is desirable to perform a gradual wall thinning process so that the radius of curvature becomes 50 mm or more.

次に、減厚部１ｂの柱軸方向における位置について説明する。減厚部１ｂは、仕口用鋼管１と梁６との接続部の上端部及び下端部から、それぞれ「ｂｃ／２」以上離れた場所に設けることが好ましい。図１の例では、梁６の上側のフランジ部６ａが仕口用鋼管１に取り付く高さが前記上端部にあたり、下側のフランジ部６ｂが仕口用鋼管１に取り付く高さが前記下端部にあたる。また、減厚部１ｂの基準となる位置としては、減厚部１ｂのうち最も梁６との接続部に近い側の柱軸方向位置を採用することができる。 Next, the position of the reduced thickness portion 1b in the column axis direction will be described. It is preferable that the reduced-thickness portion 1b is provided at a position "bc/2" or more apart from the upper end portion and the lower end portion of the connection portion between the steel pipe for connection 1 and the beam 6, respectively. In the example of FIG. 1, the height at which the upper flange portion 6a of the beam 6 is attached to the connection steel pipe 1 is the upper end portion, and the height at which the lower flange portion 6b is attached to the connection steel pipe 1 is the lower end portion. Hits. Further, as the reference position of the reduced thickness portion 1b, the column axial direction position on the side closest to the connection portion with the beam 6 in the reduced thickness portion 1b can be adopted.

より具体的には、図１の右下の吹き出し拡大図を用いて説明する。上側のフランジ部６ａと仕口用鋼管１とは、裏当て金１５を介して梁溶接部１３によって接合される。この場合、梁溶接部１３の余盛高さを考慮して、梁溶接部１３の最上部からｂｃ／２以上離れた（上側の）位置に減厚部１ｂを設けることが好ましい。図示は省略するが、下側の減厚部１ｂについては溶接部１３の最下部からｂｃ／２以上離れた（下側の）位置に減厚部を設けることが好ましい。 More specifically, a description will be given with reference to the balloon enlarged view at the lower right of FIG. The upper flange portion 6 a and the steel pipe 1 for connection are joined by the beam welded portion 13 via the backing metal 15. In this case, it is preferable that the reduced thickness portion 1b is provided at a position (upper side) bc/2 or more away from the uppermost portion of the beam welded portion 13 in consideration of the extra height of the beam welded portion 13. Although illustration is omitted, it is preferable that the reduced thickness portion 1b on the lower side is provided at a position (downward) away from the lowermost portion of the welded portion 13 by bc/2 or more.

ｂｃは、図１に示すように、仕口用鋼管１の縦断面（水平方向とは垂直な方向で切断した断面）における仕口用鋼管の増厚部同士、より具体的には縦断面における柱軸方向とは垂直方向の増厚部同士の距離であり、単位は「ｍｍ」である。増厚部同士の距離は、縦断面図における仕口用鋼管１の板厚方向中央部同士の距離を用いることもできるし、より安全に設計する際には、仕口用鋼管１の外側面同士の距離を用いることもできる。また、とりうる縦断面に応じて増厚部同士の距離が変動する場合には、最も大きい距離をｂｃとして採用すればよい。 bc is, as shown in FIG. 1, between the thickened portions of the steel pipe for connection in a vertical cross section (cross section cut in a direction perpendicular to the horizontal direction) of the steel pipe for connection 1, more specifically, in the vertical cross section. The column axis direction is the distance between the thickened portions in the vertical direction, and the unit is "mm". As the distance between the thickened portions, the distance between the central portions in the plate thickness direction of the steel pipe for connection 1 in the vertical cross-sectional view can be used, and when designing more safely, the outer surface of the steel pipe for connection 1 can be used. The distance between them can also be used. Further, when the distance between the thickened portions varies depending on the possible vertical cross section, the largest distance may be adopted as bc.

仕口用鋼管１に生じる曲げモーメントは、フランジ部６ａの取り付く高さで最大となり、仕口用鋼管１の上端面側又は下端面側へ向かうほど低下する。よって、減厚部１ｂから仕口用鋼管１と梁６との接続部の上端部又は下端部までの距離が大きい場合は、これらの距離が小さい場合に比べて、柱溶接部３及び減厚部１ｂが塑性化しにくくなり、柱梁接合構造体の変形性能が向上する。 The bending moment generated in the connection steel pipe 1 becomes maximum at the mounting height of the flange portion 6a, and decreases toward the upper end surface side or the lower end surface side of the connection steel pipe 1. Therefore, when the distance from the reduced thickness portion 1b to the upper end portion or the lower end portion of the connection portion between the connection steel pipe 1 and the beam 6 is large, the column welded portion 3 and the reduced thickness portion are compared to the case where these distances are small. The portion 1b is less likely to be plasticized, and the deformation performance of the beam-column joint structure is improved.

上記のように減厚部１ｂを前記上端部及び前記下端部からｂｃ／２以上離して設けることによって、降伏線を仮定する位置で板厚が一定となることから力学モデルが明快となって、非特許文献３に示される耐力式をそのまま用いることができる。非特許文献３で仮定する降伏線の位置は、最も降伏線が梁フランジから離れる場合であっても、その距離は梁フランジから「ｂｃ／２」の位置となる。したがって、上述した耐力式によると、減厚部１ｂを前記上端部及び前記下端部からｂｃ／２以上離すことにより、全ての降伏線を仕口用鋼管１の増厚部１ａ内に収めることができる。よって、減厚部１ｂよりも先に増厚部１ａが塑性化することを促し、柱溶接部３の破断をより確実に防止することができる。 As described above, by providing the reduced thickness portion 1b away from the upper end portion and the lower end portion by bc/2 or more, the plate thickness becomes constant at the position where the yield line is assumed, so that the dynamic model becomes clear, The load bearing formula shown in Non-Patent Document 3 can be used as it is. The position of the yield line assumed in Non-Patent Document 3 is “bc/2” from the beam flange even when the yield line is farthest from the beam flange. Therefore, according to the above-described proof formula, by separating the reduced thickness portion 1b from the upper end portion and the lower end portion by bc/2 or more, all the yield lines can be accommodated in the thickened portion 1a of the steel pipe 1 for connection. it can. Therefore, it is possible to promote plasticization of the thickened portion 1a before the reduced thickness portion 1b, and to more reliably prevent the column welded portion 3 from breaking.

以上を言い換えると、仕口用鋼管１の柱軸方向の両端に減厚部１ｂを設け、両端の減厚部１ｂの間に位置する増厚部１ａの柱軸方向長さを、「梁せい＋（梁溶接部１３の余盛り高さ）×２＋ｂｃ」以上とすることが好ましい。これにより、仕口用鋼管１に生じうる全ての降伏線を増厚部１ｂ内に収めることができ、柱溶接部３の破断をより確実に防止することができる。 In other words, the thickened portions 1b are provided at both ends in the column axial direction of the steel pipe 1 for connection, and the length in the column axial direction of the thickened portions 1a located between the thinned portions 1b at both ends is defined as "beam width". +(excessive height of the beam welded portion 13)×2+bc” or more is preferable. As a result, all yield lines that may occur in the steel pipe 1 for connection can be accommodated in the thickened portion 1b, and the breakage of the column welded portion 3 can be prevented more reliably.

尚、軸力比は、仕口用鋼管の減厚部位置の断面で０．４（無次元）程度以下で設計されることが好ましい。軸力比が０．４を超えるレベルでは、減厚部位置の塑性化が早期に生じ、塑性化後の耐力劣化も大きくなるので、軸力比は０．４程度以下に抑えることが望ましい。 The axial force ratio is preferably designed to be approximately 0.4 (dimensionless) or less in the cross section at the position of the reduced thickness portion of the steel pipe for connection. At a level where the axial force ratio exceeds 0.4, plasticization of the reduced-thickness portion position occurs early and the proof stress deterioration after plasticizing also becomes large, so it is desirable to keep the axial force ratio to about 0.4 or less.

本発明は、仕口用鋼管が、高強度鋼、例えば引張強さが７８０ＭＰａ以上の鋼によって形成される場合に特に有効である。柱と仕口用鋼管との溶接部を高強度（特に７８０ＭＰａ以上）に確保することは難しいことから、高強度鋼を仕口用鋼管として用いる場合には柱溶接部における破断の危険性が特に高くなる。本発明を適用すると、高強度鋼を用いた場合であっても、溶接部の破断を確実に防止することができる。 The present invention is particularly effective when the connection steel pipe is made of high-strength steel, for example, steel having a tensile strength of 780 MPa or more. Since it is difficult to secure a high-strength (particularly 780 MPa or more) welded portion between a column and a steel pipe for connection, when using high-strength steel as a steel pipe for connection, there is a particular risk of breakage at the welded portion of the column. Get higher When the present invention is applied, even if high-strength steel is used, it is possible to reliably prevent breakage of the welded portion.

また、構造骨組の強度をより強固にするという観点から、柱４の内側にはコンクリートを充填することもできる。 Further, from the viewpoint of further strengthening the strength of the structural frame, the inside of the pillar 4 can be filled with concrete.

尚、本発明は、ノンダイアフラム型の接合方法を用いていることから、ダイアフラムを用いる接合方法に比べて以下の（１）〜（４）のような技術的効果を奏する。
（１）施工時の溶接線の長さが少なくて済み、コストを削減することができる。
（２）梁を取り付ける態様の自由度が比較的高く、山形梁のように１つの仕口用鋼管に取り付く複数の梁の角度を変えることや、段違い梁のように複数の梁が取り付く高さを変えることも可能である。
（３）柱の外側面からの仕口用鋼管の張り出しが極めて小さいので、設備配管等の他の部材を柱に近接させる場合に、接合部構造体が邪魔になりにくい。
（４）柱の内側がダイアフラムにより仕切られていないので、柱内へのコンクリート充填が容易であり、ＣＦＴ構造とすることに適している。 Since the present invention uses the non-diaphragm type joining method, it has the following technical effects (1) to (4) as compared with the joining method using the diaphragm.
(1) The length of the welding line at the time of construction is small, and the cost can be reduced.
(2) There is a relatively high degree of freedom in the manner in which the beams are attached, and the angle at which multiple beams are attached to a single steel pipe for connection, such as a mountain beam, is changed, or the height at which multiple beams are attached, such as a stepped beam. It is also possible to change.
(3) Since the protrusion of the steel pipe for connection from the outer surface of the column is extremely small, the joint structure is less likely to get in the way when other members such as equipment piping are brought close to the column.
(4) Since the inside of the pillar is not partitioned by the diaphragm, it is easy to fill the inside of the pillar with concrete, which is suitable for forming a CFT structure.

本発明例と比較例とについて、柱梁接合構造体の破壊モデルを組み立て、計算を行った。以下の表１及び表２に結果を示す。 With respect to the example of the present invention and the comparative example, a fracture model of a beam-column joint structure was assembled and calculation was performed. The results are shown in Tables 1 and 2 below.

表１では、引張強さ４００ＭＰａ級の柱、４００ＭＰａ級の梁、及び４９０ＭＰａ級の仕口用鋼管の組み合わせで、十字骨組の破壊部位を検討した。ここで、十字骨組の梁スパンは４ｍ、柱階高は３ｍとした。これらの組み合わせはいずれも柱降伏型の組み合わせである。表１に示されているように、仕口用鋼管に本願請求項１の条件を満たすように減厚部を設けている場合には、減厚部から破壊されるが（本発明例）、そうでない場合には柱−仕口用鋼管溶接部からの早期破壊となる（比較例）。表１の例は標準的な梁スパン、階高を設定している。梁スパン、階高が大きく変化しない限り、崩壊形は変化しないと考えられる。具体的に本構造を設計する際には、梁スパン、階高、鋼種、などを設定して耐力を計算することで、崩壊形を知ることができる。 In Table 1, the fracture site of the cross frame was examined by combining a column having a tensile strength of 400 MPa, a beam having a tensile strength of 400 MPa, and a steel pipe for a connection having a pressure of 490 MPa. Here, the beam span of the cross frame was 4 m, and the height of the column floor was 3 m. All of these combinations are column yield type combinations. As shown in Table 1, when the steel pipe for connection is provided with the reduced thickness portion so as to satisfy the condition of claim 1 of the present application, it is destroyed from the reduced thickness portion (invention example), If not, early fracture occurs from the column-connection steel pipe weld (comparative example). The example in Table 1 sets the standard beam span and floor height. As long as the beam span and floor height do not change significantly, the collapse shape is considered to remain unchanged. When designing this structure, the collapse type can be known by setting the beam span, floor height, steel grade, etc. and calculating the proof stress.

表２では、引張強さ７８０ＭＰａ級の柱、５９０ＭＰａ級の梁、７８０ＭＰａ級の仕口用鋼管の組み合わせで、十字骨組の破壊部位を検討したものである。７８０ＭＰａでは、溶接部の強度を確保することが難しいが、本発明に適合する減厚部を設けることで、確実に減厚部での破壊を優先させることができる。 In Table 2, a fractured part of the cross frame is examined by a combination of a column having a tensile strength of 780 MPa class, a beam of 590 MPa class, and a steel pipe for a connection of 780 MPa class. At 780 MPa, it is difficult to secure the strength of the welded portion, but by providing the reduced thickness portion conforming to the present invention, it is possible to reliably give priority to the fracture at the reduced thickness portion.

１仕口用鋼管
１ａ増厚部
１ｂ減厚部
３柱溶接部
４柱
５裏当て金
６梁
６ａフランジ部
６ｂウェブ部
１３梁溶接部
１５裏当て金 1 Steel pipe for connection 1a Thickened part 1b Thickened part 3 Column welded part 4 Column 5 Backing metal 6 Beam 6a Flange part 6b Web part 13 Beam welded part 15 Backing metal

Claims

A non-diaphragm type column-beam joint structure having a column divided into upper and lower parts, a connection steel pipe connected to the end face of the column, and a beam joined to a side surface of the connection steel pipe,
The column and the steel pipe for connection are joined by a column weld,
The steel pipe for connection has a thickened portion having a plate thickness equal to or greater than the plate thickness of the column, and a reduced thickness portion having a plate thickness smaller than the thickened portion,
The reduced thickness portion is provided at the upper end portion and the lower end portion of the steel pipe for connection so as to be separated from the column welded portion,
The reduced thickness portion and the column welded portion are non-diaphragm type column-beam joint structures that satisfy the following formula (1).
pZp×pσy≦cZp×wσy (1)
pZp: Plastic section modulus (mm ³ ) of the steel pipe for connection in the reduced thickness portion
pσy: Yield proof strength (N/mm ² ) of the material forming the steel pipe for connection
cZp: Plastic section modulus of the column (mm ³ )
wσy: Yield strength of welding material (N/mm ² ).

The non-diaphragm type column beam according to claim 1, wherein the reduced thickness portion is provided at a position bc/2 or more away from an upper end portion and a lower end portion of a connection portion between the connection steel pipe and the beam in the column axial direction. Junction structure.
However, bc is the distance between the thickened portions in the vertical cross section of the steel pipe for connection.