JP4622796B2 - Steel pipe column base structure - Google Patents

Description

  The present invention relates to a column base structure employed in a joint between a steel column and a foundation, and more particularly to a column base structure of a steel pipe column formed of a closed cross-section member such as a square steel pipe or a round steel pipe.

  Closed cross-section members such as square steel pipes and round steel pipes are often used as pillars of steel structure buildings because of their excellent cross-sectional efficiency as compression materials. However, the closed cross-section member is often limited in the accommodation of the joint portion with the other member as compared with the open cross-section member such as H-shaped steel and groove-shaped steel.

  Conventionally, as shown in FIG. 3, the joint portion between the steel pipe column and the foundation is nut-fastened to a plurality of anchor bolts 94 planted on the base 93 by welding a base plate 92 welded to the lower end portion of the steel pipe column 91, Alternatively, as shown in FIG. 4, a column base metal 95 that can hold the column base is fastened with a bolt and a nut to the column base of the steel pipe column 91, and the column base metal 95 is planted on the foundation 93. A structure in which a nut is fastened to the anchor bolt 94 has been employed (see, for example, Patent Document 1).

However, in the column base structure as described above, the base plate 92 and the column base metal fitting 95 protrude outside the steel pipe column 91, and the joint area between the steel pipe column 91 and the foundation 93 is much larger than the cross-sectional area of the steel pipe column 91. turn into. Therefore, as a special column base structure in which the joining area can be accommodated within the cross-sectional area of the steel pipe column 91, for example, as shown in FIG. A column base structure in which 96 is welded, an anchor bolt 94 is inserted through a through hole 97 provided in the center of the base plate 96, and nuts are fastened from the inside of the steel pipe column 91 has been proposed (Patent Document 2). In this column base structure, in order to enable a nut fastening operation from the inside of the steel pipe column 91, the window-shaped opening 98 is formed on the side surface of the column base portion of the steel pipe column 91. However, the nut fastening operation is facilitated. For this purpose, it is necessary to ensure a large lateral width of the window-like opening 98, which causes a problem that the steel pipe column 91 has a cross-sectional defect that causes a reduction in yield strength.
JP-A-5-339992 Japanese Patent Laid-Open No. 9-158199

  The present invention has been made to improve the above-mentioned problems in the conventional steel pipe column base structure, and can be joined within the cross-sectional area of the steel pipe column, and the cross section of the steel pipe column does not occur. Provide structure.

In order to achieve the above-mentioned object, the steel pipe column base structure of the present invention is such that a lower end plate having a substantially same size as the cross-sectional area of the steel pipe column is fixed to the lower end portion of the steel pipe column having a closed cross section by welding. at one of the through holes is Ru is formed in a cross-section of the tubular columns, and the upper and lower forming a larger diameter than the inner diameter of the intermediate portion and the through hole forming a slightly smaller diameter cylindrical than the inner diameter of the hole A nut member that is integrally joined and has a female screw hole at its shaft center is inserted into the through hole and the lower end plate is sandwiched between the upper part and the lower part. The nut member is rotatably mounted in the through hole, and the lower surface of the nut member is formed into a polygonal shape that can engage a tool such as a spanner. The installed anchor bolt is inserted into the through hole of the lower end plate. Te by being fastened to the nut member, characterized in that the lower end of the steel column is combined with the structural framework similar basal or thereto.

  According to this steel pipe column base structure, there is no need to make the lower end plate welded to the lower end of the steel pipe column larger than the cross-sectional area of the steel pipe column, so the joint area between the column base and the foundation or similar structural frame is reduced. Can be contained within the cross-sectional area. Furthermore, since the lower part of the nut member fastened to the anchor bolt is exposed to the lower side of the lower end plate, there is no need to form a window-like opening that causes a cross-sectional defect on the side surface of the column base of the steel pipe column. The strength of the column can be maintained well.

  As a specific configuration of the nut member, the intermediate portion in the axial direction has a cylindrical shape slightly smaller than the inner diameter of the through hole, and the upper and lower portions formed above and below the intermediate portion are larger than the inner diameter of the through hole. It can be formed to have a diameter.

  Furthermore, if the lower part of the nut member has a hexagonal shape that can be engaged with a tool such as a spanner or a polygonal planar shape equivalent thereto, the screwing operation to the anchor bolt is facilitated, and workability is improved. Will improve.

  Also, if the washer is inserted into the anchor bolt and the lower part of the nut member is configured to come into contact with the foundation or a similar structural body via the washer, the nut member can be smoothly rotated and strong against the steel pipe column. Even when a compressive force is applied, the stress acting on the foundation or the like can be easily dispersed.

  In the steel pipe column base structure of the present invention, a nut member is attached to the lower end plate welded to the lower end portion of the steel pipe column, and this nut member is fastened to an anchor bolt. It is not necessary to make it larger than the area, and the joint area between the column base and the foundation or a similar structural frame can be accommodated within the cross-sectional area of the steel pipe column. In addition, the lower part of the nut member is exposed to the lower side of the lower end plate, and this lower part can be rotated with a spanner or the like. There is no need to form a shaped opening.

  When a tensile force acts on a steel pipe column, the stress is transmitted in a straight line through the path from the bottom plate → the upper part of the nut member → the female threaded part of the nut member → the anchor bolt → the foundation, etc. A sophisticated fit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a longitudinal section of a steel pipe column base structure according to an embodiment of the present invention. The steel pipe column 1 is formed of a square steel pipe or a round steel pipe, and is welded so that a lower end plate 2 having a wall thickness is inserted into the inner side of the steel pipe column 1 at the lower end thereof so as to close the lower end surface of the steel pipe column 1. It is fixed. In addition, the lower end plate 2 may be welded in a state of coming into contact with the lower end edge of the steel pipe column 1 from below.

  A through hole 21 is formed in the center of the lower end plate 2 in advance, and a nut member 3 as shown in FIG. The nut member 3 includes an intermediate portion 31 in the axial direction, and an upper portion 32 and a lower portion 33 located on the upper side and the lower side, respectively. The intermediate portion 31 is a cylindrical body that is slightly smaller in diameter than the inner diameter of the through hole 21, and is formed so that its axial length is slightly longer than the thickness of the lower end plate 2. The upper portion 32 has a planar shape that is a circle or an appropriate polygon having an outer diameter sufficiently larger than the inner diameter of the through hole 21. The lower portion 33 is formed in a hexagonal shape capable of engaging with a tool such as a spanner, or a quadrilateral or other polygonal shape equivalent thereto, and the opposed two-side width is sufficiently larger than the inner diameter of the through hole 21. It is formed to be large.

  Then, the intermediate portion 31 is inserted into the through hole 21, the upper portion 32 is disposed in the steel pipe column 1, and the lower portion 33 is mounted so as to be exposed to the lower side of the lower end plate 2, so that it cannot be removed from the through hole 21. And rotatably held in the through hole 21. The intermediate part 31, the upper part 32, and the lower part 33 are composed of upper and lower two parts including the intermediate part 31 or upper, middle, and lower three parts, and sandwich the lower end plate 2 by screw joining, caulking, welding, or the like. Are joined together.

  In the illustrated embodiment, a female screw hole 34 is formed in the shaft center of the lower portion 33, and a cylindrical hole 35 having a slightly larger diameter than the female screw hole 34 in the lower portion 33 is formed in the shaft centers of the intermediate portion 31 and the upper portion 32. . However, a female screw hole 34 having the same diameter and the same pitch as the lower portion 33 may be formed in the intermediate portion 31 and the upper portion 32.

  In this way, the steel pipe column 1 with the nut member 3 attached to the lower end plate 2 is erected at a predetermined position on the concrete foundation 4, and the nut member 3 is fastened to the anchor bolt 5 planted on the concrete foundation 4. The The nut member 3 can be easily fastened by rotating the lower portion 33 from the side with a spanner or the like. At this time, since slip occurs between the nut member 3 and the lower end plate 2, the steel pipe column 1 does not rotate. A washer 6 is inserted into the anchor bolt 5, and the washer 6 functions to smoothly rotate the nut member 3 and to disperse the vertical stress acting on the concrete foundation 4.

  In the steel pipe column base structure thus configured, when a tensile force is applied to the steel pipe column 1, the stress is applied to the lower end plate 2 → the upper part 32 of the nut member 3 → the female screw hole 34 of the nut member 3 → the anchor bolt 5 → the foundation 4 Therefore, the structure is rational and sophisticated.

  Note that the steel pipe column base structure of the present invention is not limited to a mode in which one nut member 3 is attached to the center of the lower end plate 2 and fastened to one anchor bolt 5, for example, four at the four corners of the lower end plate 2. A configuration in which the nut member 3 is attached and fastened to the four anchor bolts 5 is also included. Furthermore, not only the joining to the concrete foundation 4 as illustrated, but also the joining with other structural housings such as joint joining with the beam material and joint joining with other steel pipe columns, project from the counterpart housing. The present invention can be applied in the same form to the bolt member made, and the present invention includes a joining structure with these other structural housings. Further, the illustrated embodiment can be applied to a structure in which the upper end portion of the steel pipe column 1 is joined to a bolt member that protrudes downward from, for example, a beam member on the upper floor, by turning upside down as it is. The present invention also includes such an upside down configuration.

It is a principal part longitudinal cross-sectional view of the steel pipe column base structure which concerns on embodiment of this invention. It is a perspective view of the nut member which makes the principal part of this invention. It is a front view which shows the example of the conventional steel pipe column base structure described in patent document 1. FIG. Similarly, it is a front view which shows the example of the conventional steel pipe column base structure described in patent document 1. FIG. It is a front view which shows the example of the conventional steel pipe column base structure described in patent document 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel pipe pillar 2 Lower end plate 21 Through-hole 3 Nut member 31 Middle part 32 Upper part 33 Lower part 34 Female screw hole 4 Foundation 5 Anchor bolt 6 Washer

Claims (2)

The lower end of the steel column having a closed cross section, the lower end plate of the cross-sectional area substantially the same dimensions of the steel pipe column is secured by welding, while the through hole is Ru is formed in the cross section of the steel tube column in the lower end plate,
A nut member having a cylindrical portion having a slightly smaller diameter than the inner diameter of the through hole and an upper portion and a lower portion having a larger diameter than the inner diameter of the through hole are integrally coupled, and has a female screw hole at the axis However, in a state where the intermediate portion is inserted into the through hole and the lower end plate is sandwiched between the upper portion and the lower portion , the intermediate portion is mounted so as not to come out of the through hole and to be rotatable in the through hole.
The lower part of the nut member is formed in a polygonal shape in which the planar shape can engage a tool such as a spanner , and anchor bolts embedded in a foundation or a similar structural housing are inserted into the through holes of the lower end plate. A steel pipe column base structure in which the lower end portion of the steel pipe column is coupled to a foundation or a similar structural frame by being fastened to the nut member. The steel pipe column base structure according to claim 1, wherein a lower part of the nut member abuts against a foundation or a similar structural housing through a washer inserted into an anchor bolt .

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