JP3458179B2 - Column base fixing structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposed type column base fixing structure for supporting a column base by using an anchor bolt, and more particularly to a column base part provided with a lower nut screwed to the anchor bolt. It concerns a fixed structure.

[0002]

Bending moment M of a column base is one of the main characteristics to know the seismic resistance of this type of column base fixed structure.
And the rotation angle θ have a correlation characteristic. A test device for simulating a conventional device to obtain the correlation between M and θ is shown in FIGS. 2 and 3.

In FIGS. 2 and 3, reference numeral 100 is a test device. The test apparatus 100 is composed of various test model members as described below. 101 is a test apparatus 10
0 column base, 102 base plate, 103 concrete foundation, 104 anchor bolts, 105 anchor plate,
Reference numerals 106 and 107 denote first and second fixing portions for reinforcement, and 108.
A steel material for preventing detachment, and 109 is a load portion. In FIG. 2, bolts such as the anchor bolt 104 are simply indicated by a one-dot chain line. The numbers are actual dimensions of the test apparatus 100.

Reference numeral 111 in FIG. 3 is an upper nut for fastening the base plate 102 to the concrete foundation 103 by fastening.
12 is a lower nut. As the upper nut 111 and the lower nut 112 that model the conventional device, a standard type 1 nut corresponding to the anchor bolt 104 defined by JIS is used.

A drive source utilizing hydraulic pressure or the like is connected to the load section 109 of the test apparatus 100 having such a configuration. Then, the horizontal force F as indicated by the arrow is alternately applied from the left and right directions. The M to θ characteristics at this time are shown in FIG.
It becomes like the curve C of (a). The vertical axis represents the bending moment M (unit: tfm) applied to the column base 101, and the horizontal axis represents the rotation angle θ (unit: rad) of the base plate 102 from the reference plane.

As shown in FIG. 4 (a), in the vicinity of the 0 point, θ changes almost linearly with the increase of M, but after the yield point, the change of θ does not follow M. When the load of horizontal force is changed in the opposite direction, a so-called hysteresis characteristic is shown in which M and θ follow a history curve separated from the same locus. In the anchor bolt 104 provided with the lower nut 112, the change in M and θ after the direction change is delayed and becomes slow. Closed curve C
The internal area of the represents the amount of energy absorption capacity when an earthquake occurs.

On the other hand, regarding the test apparatus in which the lower nut 112 is omitted, M ~ obtained from the experimental results under the same conditions as described above.
The θ characteristic is shown by the curve C in FIG. 4 (b). In the case of the anchor bolt 104 in which the lower nut 112 is omitted, the rotation angle θ is rapidly changed near the bending moment M of 0 after yielding. A rapid change in the rotation angle θ as shown in the second and fourth quadrants of Fig. (B) is commonly called "slip phenomenon", which is an unfavorable phenomenon in a supporting leg that supports a building. Of FIG.
As is clear from the characteristic diagrams of (a) and (b), the lower nut 11
2 serves to prevent the "slip phenomenon".

[0008]

A conventional lower nut 112 is used.
According to the fixing structure of the column base portion using, the "slip phenomenon" is prevented as described above. However, when the compression force Fd is applied to the anchor bolt 104 via the lower nut 112 based on the load of the horizontal force applied alternately, this compression force Fd is applied to the concrete foundation 103 with the fixing plate 105 as a base point. Become. As a result, there has been a problem that there is a possibility that the cone may be destroyed over the angular range of about 90 degrees as indicated by the broken line X in the figure.

The present invention has been made to solve the above-mentioned problems of the column base portion using the conventional lower nut, and prevents the column base portion from slipping and suppressing the compressive force. The purpose of the present invention is to realize a fixing structure for a column base that reduces the cone breakage caused by the leverage of the lever.

[0010]

SUMMARY OF THE INVENTION The present invention provides a concrete
Screw on the top screw of the anchor bolt embedded in the
Insert the base plate between the mating upper and lower nuts.
The structure for fixing the column base that holds and supports the column base
Based on the bending moment that acts on the column base alternately.
The tensile and compressive forces applied to the anchor bolts
In order to suppress the transmission on the compression force side,
For the standard parts group of JIS for the upper and lower nuts,
Characterized by combining the JIS 3 type nut group with the nut
This is a structure for fixing the column base .

Embedded in a concrete foundation
The upper nut and lower nut that engage with the upper screw of the anchor bolt
Support the column base by sandwiching the base plate between
In the fixed structure of the column base to be held, alternately to the column base
To the anchor bolt based on the acting bending moment
Transmission of the applied tensile force and compressive force on the compressive side
In order to suppress, the anchor bolt and upper nut JIS
The low column of JIS is combined with the lower nut of the standard component group of No. 3, and the fixing structure of the column base is constituted.

[0012]

[Operation] When an earthquake occurs, alternating horizontal force is applied to the column base due to the vibration. At the same time, the tensile force and the compressive force act on the left and right anchor bolts, and the compressive force of the anchor bolts is about to be transmitted to the foundation concrete through the fixing plate. At this time, since a lower nut is used as the lower nut, the compressive force transmitted to the fixing plate is suppressed, and the occurrence of cone breakage in the basic concrete is prevented.

[0013]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of the configuration of the first embodiment of the present invention.
In the embodiments of the present invention, the portions corresponding to the conventional structure are given different reference numerals, so that the description will be partially duplicated but will be described in some detail.

Reference numeral 2 is waste concrete, 3 is a support frame, and 4 is a plurality of anchor bolts. The discarded concrete 2 is placed on the excavated ground (root cutting bottom) of the construction site of the building, and the support frame 3 is fixed by the Hawks strike anchor 21 embedded in the discarded concrete 2. Three
3 is a frame base of the support frame 3, 34 is a frame post, and 35 is a fixing plate provided with an insertion hole.

The anchor bolts 4 are of the eight-anchor bolt type here and are erected on the support frame 3. 5
6 and 6 are the upper nut and the lower nut, which are made in a combination of upper and lower parts. In the upper and lower combination nuts 5 and 6, especially the upper nut 5 is composed of an upper nut 51 and a lower nut 52.

The upper nut 5 excluding the lower nut 52
As the upper nut 51 and the lower nut 6, one kind of nut corresponding to the anchor bolt 4 defined by JIS is used. In particular, in this embodiment, the lower nut 52 is a low nut having a low nut height and a small pitch, which is listed in the JIS list.

Reference numeral 8 is a rectangular base plate, 9 is a column base, and 1 is a base.
0 is grout material. 2 in each corner of the base plate 8
A total of eight insertion holes are provided, and eight anchor bolts 4 are respectively inserted and integrally connected. In addition, although not all shown in FIG. 1, 1 is the ground, 7
Is a concrete foundation.

The operation of the embodiment of the present invention having the above construction will be described below. At the planned construction site of the building, root cutting will be carried out to a depth according to the scale of the building. Then, crushed gravel is sprinkled on the stones arranged on the root cutting bottom, and the discarded concrete 2 in which the hawk's strike anchor 21 is filled is placed. On the surface of the discarded concrete 2 which has been smoothed after the curing period, a pillar core or the like made of a tattoo is clearly indicated.

On the other hand, the building materials for the foundation such as the support frame 3, the anchor bolts 4, the upper and lower combined nuts 5 and 6 are prepared in advance and carried to the construction site. First, after assembling the support frame 3 on the discarded concrete 2, eight anchor bolts 4 are erected on the fixing plates 35 provided at the four corners of the support frame 3 using the lower nuts 6 of the combination type. It The height of the upright anchor bolt 4 is adjusted.

After adjustment, an attachment plate (not shown) is attached to the upper portion of the eight anchor bolts 4 between the upper nut 51 and the lower nut 52. At this time, if necessary, the verticality and horizontality of the anchor bolt 4 are checked. After that, the reinforcement of the underground beam and foundation rise is given,
The foundation work of the column base is completed by placing and hardening the concrete foundation 7. When the foundation work is completed, the formwork is removed and the root cutting is backfilled.

After the concrete is poured, the upper nut 51 is loosened and the attachment plate is removed. Then, the mortar (commonly known as bun) is brought out to a horizontal level, and the holes of the base plate 8 of the column base 9 carried by the crane are inserted into the anchor bolts 4. The upper nut 51 is attached to the anchor bolt 4 exposed from the hole.
Are screwed together and the base plate 8 is tightened. The base plate 8 is surrounded by a shackle, and the grout 1
0 is injected, and the steel frame erection using the column base 9 is completed.

When an earthquake occurs in the embodiment of the present invention having such a structure, an alternating horizontal force F similar to that in FIG. 2 is applied to the column base 9 by the vibration. At the same time, a tensile force (tensile stress) Fu and a compressive force (compressive stress) Fd act on the left and right anchor bolts 4, and the compressive force Fd of the anchor bolts 4 tries to be transmitted to the basic concrete 7 through the fixing plate 35.

However, the upper nut 5 is attached to the lower nut 52.
Since a low nut having a smaller number of pitches than 1 is used, the compressive force Fd transmitted to the fixing plate 35 is the tensile force Fu.
It will be suppressed to a smaller value. As a result, it is possible to reduce or prevent the cone breakage generated in the basic concrete 7 based on the compressive force Fd.

Example 2 In Example 2 of the present invention, although the drawings are not specifically referred to,
A JIS standard type 3 nut is used for the lower nut 52.
The three types of lower nuts 52 have a slightly higher height than the low nut of the first embodiment, and the screwing area with the anchor bolt 4 is wide. Also in the case of the second embodiment of the three kinds of lower nuts 52, the transmission of the compressive force Fd is suppressed and the cone breakage is reduced as in the case of the first embodiment.

Incidentally, each pitch of the JIS standard anchor bolt group and height examples of the corresponding 1st, 3rd type nuts and low nuts corresponding thereto are shown below. Anchor bolt Pitch type 1 nut Type 3 nut Low nut M24 × 3 19 14 12 M27 × 3 22 16 13.5 M30 × 3.5 24 18 15 M36 × 4 29 21 18 M42 × 4.5 34 25 21 M48 × 5 38 29 24 M56 x 5.5 45 45 34 28 M64 x 6 51 38 32 (Unit: mm)

In the above embodiment, the case where the side plate is removed and the column base is fixed has been described, but the column base may be fixed while the side plate is attached. Further, although the description has been made on the column base of the eight-anchor bolt system, the present invention can be applied to the four-anchor bolt system. further,
The embodiment exemplifies a case where a lower nut having a lower height (smaller pitch) and a third-class nut are used for the lower nut .

[0027]

The present invention is embedded in a concrete foundation.
Upper nut that is screwed onto the upper screw of the anchor bolt
The base plate between the lower nut and the lower nut,
In the fixed structure of the column base that is fixed and supported,
Anchor based on alternating bending moments
Compressive force side of tensile force and compressive force applied to bolt
The anchor bolt and upper nut in order to suppress the transmission of
In contrast to the JIS standard parts group of
Of the column base, which is characterized by combining three types of nut groups
A fixed structure was constructed.

Also embedded in the concrete foundation
The upper nut and lower nut that engage with the upper screw of the anchor bolt
Support the column base by sandwiching the base plate between
In the fixed structure of the column base to be held, alternately to the column base
To the anchor bolt based on the acting bending moment
Transmission of the applied tensile force and compressive force on the compressive side
In order to suppress, the anchor bolt and upper nut JIS
The lower base nut is combined with the low nut group of JIS in the above-mentioned standard parts group, and the fixing structure of the column base is constituted.

As a result, the slip phenomenon can be prevented by the lower nut, and at the same time, the destruction of the cone in the concrete foundation due to the compressive force can be prevented.

Therefore, according to the present invention, it is possible to provide the fixing structure for the column base portion which has no failure due to the slip phenomenon and has a large energy absorption capacity in the event of an earthquake.

[Brief description of drawings]

FIG. 1 is a configuration explanatory diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an M-θ characteristic test device that models a conventional device.

FIG. 3 is a partially enlarged sectional view of FIG.

FIG. 4 is an explanatory diagram of M to θ characteristics.

[Explanation of symbols]

1 ground 2 Discarded concrete 3 support frames 4 anchor bolts 5 Upper nut 6 Lower nut 7 Concrete foundation 8 base plate 9 Pillars 35 fixing plate 51 Upper nut 52 Lower nut F Horizontal force

─────────────────────────────────────────────────── ─── Continued Front Page (72) Masami Sakai 2-1-1 Shiraishi-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Nihon Foundry Co., Ltd. (72) Shinji Suzuki 2-1-1 Shiraishi-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Nihon Foundry Co., Ltd. (72) Inventor Toshiaki Miyao 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihonkokan Co., Ltd. (56) Reference JP-A-4-80428 (JP, A) JP-A-7-305356 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) E02D 27/42 E04B 1/24

Claims (2)

(57) [Claims] 1. An ann embedded in a concrete foundation.
An upper nut and a lower nut that are screwed to the upper screw of the car bolt
The base plate is sandwiched between and the column base is fixed and supported.
In the fixed structure of the column base, the front structure is based on the bending moment that acts alternately on the column base.
The tensile and compressive forces applied to the anchor bolt
In order to suppress the transmission on the compression force side, the anchor bolt and the upper nut are combined with the JIS standard part group, and the lower nut is combined with the JIS class 3 nut group. Fixed structure. 2. An ann embedded in a concrete foundation.
An upper nut and a lower nut that are screwed to the upper screw of the car bolt
The base plate is sandwiched between and the column base is fixed and supported.
In the fixed structure of the column base, the front structure is based on the bending moment that acts alternately on the column base.
The tensile and compressive forces applied to the anchor bolt
In order to suppress the transmission on the compression force side, the column base is fixed by combining the lower nut with the JIS low nut group against the JIS standard part group of the anchor bolt and the upper nut. Construction.