JP2000282571A - Fixing structure of exposed column base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the fixing structure of an exposed column base withstanding even excess shear force by simple structure. SOLUTION: In the fixing structure of the exposed column base in which the upper-end screw sections of anchor bolts 5 buried in foundation concrete 6 are inserted into the boltholes of a base plate 7 fixed onto the column base 10, the base plate 7 is pinched by upper nuts 8a and lower nuts 8b screwed onto the upper-end screw sections of the anchor bolts 5 and the column base 10 is fixed, openings among the anchor bolts 5 and the anchor boltholes of the base plate 7 are filled with a grout 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for fixing an exposed column base in an exposed column base construction method.

[0002]

2. Description of the Related Art An exposed column base method is a method of fixing a steel column on a foundation concrete by tightening a nut on a base plate welded to a lower end portion of the steel column and an anchor bolt buried in the foundation concrete. It is. FIG. 5 is a side view of a fixing structure of an exposed column base in a conventional exposed column base construction method, and FIG. 6 is a plan view thereof. A conventional fixing structure for an exposed column base will be described with reference to FIGS. In the figure, 1 is discarded concrete, 2 is discarded concrete 1
An anchor frame 3 erected on the upper side is a hole-in anchor for fixing the anchor frame 2 to the concrete 1 to be discarded, and 4 is provided at an upper end portion of the anchor frame 2 to fix an anchor bolt 5 described later. It is a board.

[0005] 5 is an anchor bolt installed on the fixing plate 4, 6 is a foundation concrete cast on the discarded concrete 1 to near the upper end of the anchor bolt 5, 7 is a base plate installed on the upper end of the anchor bolt 5 , 8 are double nuts screwed to the upper end of the anchor bolt 5,
9 is a washer placed between the double nut 8 and the base plate 7, 10 is a steel column with the base plate 7 welded to the lower end, 11 is the base plate 7 and the foundation concrete 6
It is a grout material cast between.

FIGS. 7 and 8 are explanatory views of a force transmission mechanism in the fixing structure of the exposed column base constructed as described above. In the figures, N denotes an axial force acting on the steel column
M indicates a bending moment, and Q indicates a shear force. Among the stresses acting on the steel column 10, the axial force N and the bending moment M are the tensile force T of the anchor bolt 5 and the grout material 11.
Is transmitted to the foundation concrete 6 as a compression reaction force C.

[0005] The shearing force Q is transmitted to the foundation concrete 6 by the frictional force between the base plate 7 and the grout 11 due to the compression reaction force C. When a large shear force Q that cannot be processed by the above-mentioned frictional force acts, the shear force Q is changed from the base plate 7 to the washer 9.
→ Anchor bolt 5 → foundation concrete 6 will flow.

In order to cope with such a large shear force Q, at present, as shown in FIGS. 9 and 10, a large-size washer 9 capable of bearing the above-mentioned shear force is used. 7, a fillet weld 12 having a necessary throat thickness is provided. The screw length is generally limited to a part of the thickness of the washer so that the screw portion of the anchor bolt 5 does not form a shear plane.

In recent years, in terms of restoring force characteristics between the bending moment M and the rotation angle θ of the base plate, slips are less likely to occur and energy absorption capacity is improved, so that nuts are installed one above and below the base plate one by one. A so-called lower nut type exposed column base fixing structure has been adopted.

[0008]

In the conventional fixing structure for an exposed column base, when an excessive shearing force is applied, the anchoring bolt 5 bears the shearing force. In this case, as described above. And washer 9 thicker than normal size
And the fillet welding of the washer 9 and the base plate 7 must be performed, and there is a problem that the construction is complicated.
This point is the same in the lower nut type.

[0009] Another problem inherent in the use of the above conventional method in the lower nut method is that if the strength of the welded portion is insufficient and the anchor bolt comes into contact with the side surface of the anchor bolt hole. There is a point contact state which is not preferable.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a fixing structure for an exposed column base which has a simple structure and can withstand an excessive shearing force.

[0011]

According to the present invention, there is provided a fixing structure for an exposed column base, wherein an upper end screw portion of an anchor bolt embedded in a foundation concrete is inserted into a bolt hole of a base plate fixed to the column base. In an exposed column base fixing structure for fixing a column base by holding the base plate between an upper nut and a lower nut screwed into an upper end screw portion of the anchor bolt, the base plate is fixed to an anchor bolt hole of the base plate. The gap is filled with a grout material.

[0012]

FIG. 1 is a side view of a fixing structure for an exposed column base according to the present invention, FIG. 2 is a plan view thereof, and FIGS. 3 and 4 are enlarged views of essential parts. In the figure, the same or corresponding parts as in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. Only different parts will be described. In the drawing, reference numerals 8a and 8b denote upper nuts and lower nuts, respectively, which are provided with the base plate 7 interposed therebetween. Reference numerals 15 denote washers provided between the upper nut 8a and the base plate 7. Unlike the conventional example, the washer 15 has a normal size and is not welded to the base plate 7. Reference numeral 17 denotes a grout material injected between the anchor bolt 5 and the anchor bolt hole of the base plate 7 (see FIG. 3).

Next, the construction procedure of the above structure will be outlined. Anchor frame 2 is erected on abandoned concrete 1
Fix with hole-in anchor 3. Anchor frame 2
The four anchor bolts 5 are erected on the fixing plate 4 attached to the base plate to adjust the height. After the adjustment, an attachment plate (not shown) is attached above the lower nut 8b, and the verticality and the horizontality of the anchor bolt 5 are checked and adjusted.

After that, the foundation concrete 6 is poured, and after the foundation concrete 6 is hardened, the attachment plate is removed.
Serve horizontal level with mortar (commonly known as bun). After that, the steel column 10 to which the base plate 7 is welded is carried in, and the bolt holes of the base plate 7 are inserted into anchor bolts to be erected. Then, after rebuilding the steel column 10, before the upper nut 8a is tightened, the gap between the anchor bolt 5 and the anchor bolt hole of the base plate 7 is filled with the grout material 17, and after confirming the filling, the upper nut 8a is tightened. Finally, the grout material 11 is filled between the base plate 7 and the foundation concrete 6.

In the fixing structure of the exposed column base according to the present embodiment configured as described above, when a large shearing force that cannot be handled by the frictional force between the base plate 7 and the grout material 11 acts, The shear force flows from the base plate 7 → the grout material 17 → the anchor bolt 5 → the foundation concrete. At this time, the grout material 17
Are the lower nut 8b, the upper nut 8a and the base plate 7
Is filled in a narrow space constrained on all sides, so that when a shearing force is applied, a three-dimensional stress state is achieved, and a large strength is exhibited. Therefore, the grout material 17 and the anchor bolt 5 can exchange force over the entire screw portion of the anchor bolt 5. Therefore, even when an excessive shear force is applied, the anchor bolt 5 can bear the shear force without using the washer 15 of the normal size and without fillet welding between the washer 15 and the base plate 7. .

[0016]

As described above, in the present invention, the grout material is filled in the gap between the anchor bolt and the anchor bolt hole of the base plate. It becomes a dimensional stress state and exerts a large strength, so that the grout material and the anchor bolt can exchange force with the entire screw portion of the anchor bolt. For this reason, it is possible to use an ordinary size washer, and without using a fillet weld between the washer and the base plate, to allow the anchor bolt to bear the shearing force. Can be realized.

[Brief description of the drawings]

FIG. 1 is a side view of a fixing structure for an exposed column base according to an embodiment of the present invention.

FIG. 2 is a plan view of a fixing structure of the exposed column base according to the embodiment of the present invention.

FIG. 3 is an enlarged view of a main part of the fixing structure of the exposed column base according to the embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of the fixing structure of the exposed column base according to the embodiment of the present invention.

FIG. 5 is a side view of a conventional fixing structure for an exposed column base.

FIG. 6 is a plan view of a conventional fixing structure for an exposed column base.

FIG. 7 is an explanatory view of a force transmission mechanism in a conventional fixing structure for an exposed column base.

FIG. 8 is an explanatory view of a force transmission mechanism in a conventional fixing structure for an exposed column base.

FIG. 9 is a partially enlarged view of a conventional fixing structure for an exposed column base.

FIG. 10 is a partially enlarged view of a conventional fixing structure for an exposed column base.

[Explanation of symbols]

 5 Anchor bolt 7 Base plate 8a Upper nut 8b Lower nut 15 Washer 17 Grout material

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuhisa Imamoto 1-2-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. 2D046 AA16 AA17 2E125 AA01 AA04 AB16 AC14 AC16 AG03 AG12 AG43 AG60 BE10 CA04 CA82

Claims (1)

[Claims] 1. An upper nut for inserting an upper end screw portion of an anchor bolt embedded in a foundation concrete into a bolt hole of a base plate fixed to a column base, and screwing the base plate to an upper end screw portion of the anchor bolt. An exposed column base fixing structure for fixing a column base by being clamped by a lower nut, wherein a grout material is filled in a gap between the anchor bolt and an anchor bolt hole of the base plate. Fixed structure.