JPH0754347Y2 - Steel column base - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel column base mainly used for a steel building.

[0002]

2. Description of the Related Art As shown in FIG. 6, a steel frame column base 10 of a steel frame building includes a steel frame column 1, a base plate 2 attached to the lower end thereof by welding or the like, and an anchor bolt assembly 3.
And the basic concrete 4. The anchor bolt assembly 3 includes an anchor bolt 5, a flat washer 6 and a nut 7 screwed to an upper end screw portion 5a of the anchor bolt 5, and a pair of nuts screwed to a lower end screw portion 5b of the anchor bolt 5. The fixing plate 9 is fixed to the anchor bolt 5 by being sandwiched between the nuts 8a and 8b.

In such a steel column base 10, as shown in FIG. 7, the steel column 1 is subjected to the weight of the building and the axial force N and horizontal force F due to an earthquake or storm. Due to the horizontal force F, a bending moment M for bending the steel column base 10 and a shearing force Q for moving it horizontally are generated.

For bending moment M and axial force N,
The steel column base 10 is designed so that the stress is transmitted from the steel frame column 1 to the base plate 2, the anchor bolt 5, and the foundation concrete 4 in this order. For shearing force Q,
When the value is small, the stress is designed to be transmitted from the steel frame column 1 to the base plate 2 and the foundation concrete 4 in this order.

In this case, the stress is transmitted from the base plate 2 to the base concrete 4 by the frictional force Qa between the base plate 2 and the base concrete 4 caused by the axial force N acting on the steel column base 10 and the anchor bolt tensile force.
_Done by ₁ .

Further, the value of the shearing force Q is large, and the frictional resistance force Qa ₁ between the base plate 2 and the foundation concrete 4
Is designed to transmit stress in the order of the steel column 1, the base plate 2, the flat washer 6, the anchor bolt 5, and the foundation concrete 4 when the shear force Q cannot be resisted. For this purpose, the anchor bolt 5 and the base plate 2
As shown in FIG. 8, the flat washer 7 having an inner hole with a small clearance with respect to the outer diameter of the anchor bolt 5 and the base plate 2 are fillet welded all around for the purpose of reducing the clearance between the hole 2a and the hole 2a. It had been. 11 welds
Indicated by.

By the way, recently, due to the concept of seismic design, there is a growing need to increase the bearing capacity of the steel column pedestal 10, and in order to realize this, good mechanical properties (yield point and The adoption of anchor bolts (with high tensile strength) is one of the important factors.

[0008]

[Problems to be Solved by the Invention] However, when an anchor bolt having a tensile strength of 50 kg / mm ² or more is conventionally used for a steel column post 10, a flat washer 6 and the like made of the same material as the anchor bolt, which is generally a set part, are used. Was high in carbon content and carbon equivalent (Ceq), and could not be welded to the base plate. Therefore, when the anchor bolt having the high strength (tensile strength of 50 kg / mm ² or more) is used, a large shearing force Q cannot be transmitted from the base plate 2 to the anchor bolt 5. As a result, when this high-strength anchor bolt is used, the bending strength Ma of the steel column base 10 (the strength that resists the bending moment M) is improved, but the shear strength Qa is the friction between the base plate 2 and the foundation concrete 4. Resistance Qa ₁
However, there was a problem that it could be secured only at that time, and it would rather decrease.

The object of the present invention is to provide a steel column base that solves these problems.

[0010]

The steel column base of the present invention comprises a base plate, an anchor bolt, a flat washer and a nut, and the anchor bolt is 50 to 70 kg / m.
made of a material having a tensile strength of m ^2, the flat washer whole to the base plate with consisting welding structural steel
The flat washer has an outer diameter of 1.73 times or more the threaded portion outer diameter of the anchor bolt and a thickness of 0.13 times or more the threaded portion outer diameter of the anchor bolt. The difference between the inner diameter of the flat washer and the outer diameter of the threaded portion of the anchor bolt is within 2 mm, the nut is made of general structural steel or welded structural steel, and the entire circumference of the plain washer
It is characterized by being fillet welded and having a height of about 0.92 to 1.40 times the outer diameter of the threaded portion of the anchor bolt. In the above-mentioned steel-framed column base, it is preferred that the above-mentioned flat washer is fillet-welded to the above-mentioned base plate all around.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an anchor bolt assembly 20 used in a steel column base of the present invention. This is fixed to the anchor bolt 21, the nut 22 screwed to the upper end screw portion 21a thereof, the flat washer 23 interposed between the fastened body (base plate), and the lower end screw portion 21b of the anchor bolt 21. Pair of nuts 24
The fixing plate 25 is fixed by a and 24b.

The anchor bolt 21 has a tensile strength of 50 to 70 kg.
/ Mm ² material, concretely SS50, SS5
5, SR30, SRR40, SD30, SD35, SD
40, SD50, S30C, S35C, S40C, S4
It consists of 5C, S50C and S55C. The flat washer 23 is made of a welded structural steel material, particularly SM50 or SMA50. The outer diameter of the flat washer 23 is the same as the outer diameter of the anchor bolt 21.
1.73 times or more, and the thickness is 0 of the outer diameter of the anchor bolt 21.
13 times or more. The inner diameter is set between the screw outer diameter of the anchor bolt 21 and the screw outer diameter +2 mm. The nut 22 is preferably made of the same material as the anchor bolt 21.

FIG. 2 shows an anchor bolt assembly 30 used for a steel column base according to another embodiment of the present invention. Anchor bolt 31
The material of the flat washer 33 is the same as that of FIG. The nuts 34a, 34b and the fixing plate 35 are also the same as those in FIG. The first feature of this embodiment is that the nut 32 has a general structural steel material and a welded structural steel material, specifically SS4.
1, SM41 and SMA41. The second feature is that the height of the nut 32 is about 0.92 to 1.40 times the outer diameter of the threaded portion of the anchor bolt 31. This corresponds to 1.15 to 1.75 times the height specified by JIS (about 0.8 times the outer diameter of the screw of the anchor bolt). The shapes of the other parts are the same as those in FIG.

Using the anchor bolt assembly 20 for a steel column base according to the embodiment shown in FIG.
You can expect a high tensile strength of 50 to 70 kg / mm ² , and at the same time,
Since the flat washer 23 is made of the material of SM50 or SMA50, the flat washer 23 and the base plate 2 can be welded well, so that a high shear proof Qa can be secured to the steel column base. As a result, the shearing force Q generated in the steel column 1 can be smoothly transmitted to the foundation concrete 4 via the base plate 2, the flat washer 23 and the anchor bolt 21.

Further, according to the present invention, the standard of flat washers according to JIS B1256 "hardness class 14H of plain washers when using bolts whose strength class is 4.6 to 6.8 (Vickers hardness HV14
0) is secured. Can also be satisfied.

Further, by using the flat washer 23 of the present invention, it is possible to perform fillet welding on the entire circumference. In this case, if the outer diameter of the plain washer 23 is 1.73 times or more the screw outer diameter of the anchor bolt and the thickness is 0.13 times or more the screw outer diameter of the anchor bolt, as can be seen from the following calculation, the anchor bolt 21 full strength shear strength _B
Q _a can be covered.

(A) Total strong shear strength _{B of the} anchor bolt
_{Q a B Q a = 0.75 ×} (π / 4) · d 2 × f 1/3 1/2 ≒ 0.95
d ² d: Anchor bolt screw outer diameter f ₁ : Anchor bolt yield point ≈ 2.8 t / cm ²

[0018] (b) flat washer entire circumference of the fillet weld shear strength _{W Q a W Q a = πD} × t / 2 1/2 × f 2/3 1/2 ≒ 7.3td D: flat washer outside of Diameter ≧ 1.73 d t: Thickness of plain washer f ₂ : Allowable tensile stress of fillet weld = 3.3 t / cm ²

(C) Conditions under which the shear strength _W Q _a of the fillet weld around the entire flat washer is greater than the total strength shear strength _B Q _{a of the} anchor bolt _B Q _a ≤ _W Q _a ∴ 0.95d ² ≤ 7.3td ∴t ≧ 0.13d

Furthermore, since the inner diameter of the flat washer 23 is between the screw outer diameter of the anchor bolt and the screw outer diameter of the anchor bolt +2 mm, the shear force Q acting on the steel column base 10 makes the steel column base 10 horizontal. Even if it shifts in the direction, the maximum amount is 4 mm. Therefore, as shown in FIG. 3, the interlayer deformation angle γ (= δ / h) obtained by dividing the horizontal displacement amount δ of the pillar 1 of the first floor of the building at that time by the height h of the first floor is Assuming that the floor height h is 3500 mm, which is a general value, it is about 1/875, which is within the range of fully satisfying the current legal standard of 1/200.

In the steel column base of another embodiment of the present invention (FIG. 2), the nut 32 is made of a material having the same proof performance as that of the anchor bolt 31 and can be welded to the flat washer 33 and the fillet of the entire circumference. Are using. Since this nut 32 is a weldable material, it has low mechanical properties (yield point, tensile strength), but a screw equivalent to the standard nut (same material as the anchor bolt 31) specified in JIS. In order to have strength of other parts, the height of the anchor bolt 31 is 1.15 to 1.75 times the height of the nut defined by JIS.

The proof of the numerical values is as follows.

(A) Strength of thread portion of nut of same material as anchor bolt Ta Ta = Sn = S · H / P S: Thread strength of nut of same material of anchor bolt n: Nut of same material of anchor bolt Number of threads H: Height of the nut made of the same material as the anchor bolt as specified by JIS P: Thread pitch of the nut made of the same material as the anchor bolt

(B) Strength of thread portion of nut 32 of the second embodiment Ta 'Ta' = S'.n '= S'.H' / P S ': Strength of thread of nut 32 of the second embodiment n ′: the number of threads of the nut 32 of the second embodiment H ′: the height of the threads of the nut 32 of the second embodiment P: the thread pitch of the nut 32 of the second embodiment (same as the pitch of (a)) )

(C) Conditions for equal thread strength between the nut 32 of the second embodiment and the nut of the same material as the anchor bolt Ta = Ta'∴S · H / P = S ′ · H '/ P∴ H ′ = (S / S ′) × H

Here, S / S 'is the ratio of the anchor bolt and the yield point of the nut 32 of the second embodiment, which is 1.15 to 1.75 in the combination according to the present invention. ∴ 1.15H ≤ H'≤ 1.75H

If the flat washer 33 and the base plate 2 and the flat washer 33 and the nut 32 are welded around the entire circumference using the anchor bolt assembly 30 for the steel column base, the anchor bolt 31 is attached to the steel column base 10. It is possible to secure the full shear strength Qa and to prevent the nut 32 from loosening.

An anchor bolt assembly for a steel column base according to the present invention is shown in FIGS. 1 and 2, which has a fixing plate 5 at the lowermost end of the anchor bolt. Similar effects can be obtained even when the lowermost end of the anchor bolt is bent in J shape or L shape.

[0029]

[Effects of the Invention] The following effects can be expected when the steel column base according to the present invention is used in a steel building or the like. (A) The bending strength Ma and the shear strength Qa of the steel column base can be increased at the same time. (50 to 70 for anchor bolts
The tensile strength of Kg / mm ² can be secured, and at the same time, the full shear strength _B Q _a of the anchor bolt can be secured. (B) It is possible to prevent loosening of anchor bolts with a tensile strength of 50 to 70 kg / mm ² .

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an anchor bolt assembly for a steel column base according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing an anchor bolt assembly for a steel column base according to another embodiment of the present invention.

FIG. 3 is a view showing interlayer deformation of a building using the steel column base of the present invention.

FIG. 4 is a partial cross-sectional view showing still another example of the anchor bolt assembly for a steel column base of the present invention.

FIG. 5 is a partial sectional view showing still another example of the anchor bolt assembly for a steel column base of the present invention.

FIG. 6 is a view showing a conventional steel column base.

FIG. 7 is a diagram showing an external force acting on the anchor bolt assembly for a steel column base of FIG. 6.

FIG. 8 is a view showing a state where a conventional flat washer of a steel column base is welded to a base plate.

[Explanation of symbols] 1 ... Steel column 2 ... Base plate 3, 20 ・ 30 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Anchor bolt assembly 4 ・ ・ ・ ・ ・ ・ ・ ・ Foundation concrete 5,21,31 ・·························································································· ... Nuts 8a, 8b, 24a, 24b, 34a, 34b ... Nuts 9, 25, 35 ... Fixing plate 10 ...・ ・ ・ ・ ・ Steel column base

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Kitano, Takashi Kitano, 1-9-1, Kitahama, Wakamatsu-ku, Kitakyushu, Fukuoka Inside the Wakamatsu Factory, Hitachi Metals, Ltd. (72) Kuniaki Sato, Moto-Akasaka 2-chome, Minato-ku, Tokyo No. 7 within Kashima Construction Co., Ltd. (56) References Japanese Patent Publication No. 61-1574 (JP, B2) Japanese Patent Publication No. 56-30425 (JP, B2)

Claims (1)

[Scope of utility model registration request] 1. A steel column base using a fastening body composed of a base plate, an anchor bolt, a plain washer, and a nut, wherein the anchor bolt is made of a material having a tensile strength of 50 to 70 kg / mm ² . The flat washer is made of welded structural steel, and the base plate has a fillet around the entire circumference.
Are welded, the outer diameter of the flat washer is 1.73 times or more the outer diameter of the threaded portion of the anchor bolt, and the thickness is 0.13 times or more the outer diameter of the threaded portion of the anchor bolt. The difference between the inner diameter of the anchor bolt and the outer diameter of the thread of the anchor bolt is 2
mm, the nut is made of steel for general structure or steel for welded structure, and the fillet melts around the flat washer.
A steel column base, which is in contact with the anchor bolt and has a height of about 0.92 to 1.40 times the outer diameter of the threaded portion of the anchor bolt.