JPH1025747A - Fixing structure of steel-framed column base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesion of an anchor bolt by forming the anchor bolt buried into foundation concrete of a screw-knotted reinforcement and screwing a lock-nut having specific height to the upper section of a nut having specific height. SOLUTION: An anchor bolt 17 is formed of a screw-knotted reinforcement. A nut 16 is formed in height size H(=(3-6)P (P represents the pitch size of the knot of the screw-knotted reinforcement). A lock-nut 19 is formed in height size h=1.5P or more and h<H1 . A column-base fitting 11 is joined integrally at the lower end section of a steel-framed column 12 consisting of a square steel pipe, etc., by welding, and a steel-framed column base 13 is formed. The anchor bolt 17 is positioned and fixed to a support member 4 by nuts 6 while being buried into foundation concrete 9. The upper end sections of the anchor bolt 17 are inserted into the boltholes of the column-base fitting 11 while nuts 16 are screwed at the upper end sections of the anchor bolt 17 and the steel- framed column base 13 is fixed, and the lock-nuts 19 are screwed through spring washers 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing structure of a steel column base for fixing a steel column base constituting a building on foundation concrete.

[0002]

2. Description of the Related Art FIG. 5 is a longitudinal sectional view of an essential part showing an example of a conventional fixing structure for a steel column base. In FIG. 5, reference numeral 1 denotes a support, which is erected at an appropriate interval on a discarded concrete 3 provided on a split chestnut 2, and a support member 4 is horizontally fixed to an upper end of the support 1. . Next, reference numeral 5 denotes an anchor bolt, which is formed of a steel bar, and has screws (not shown) at upper and lower ends.

The anchor bolt 5 engages a nut 6 and a fixing plate 7 to be positioned and fixed to the support member 4.
The base concrete 9 is cast with the hollow cylindrical sleeve 8 inserted. After the foundation concrete 9 is cured and set, the steel column base 13 formed by joining the column base metal 11 to the lower end of the steel column 12 via the central mortar 10 is placed,
After positioning, the non-shrink mortar 14 is filled between the column base hardware 11 and the foundation concrete 9.

A washer 1 is provided at the upper end of the anchor bolt 5.
The steel column base 13 is fixed on the foundation concrete 9 by mounting the nut 5 and the nut 16 and tightening the nut 16. It is to be noted that reinforcing steel bars are usually provided in the foundation concrete 9, but are not shown in FIG.

[0005]

FIG. 6 is an explanatory view showing a state of an external force acting on the anchoring structure of a conventional steel column base.
The same parts are indicated by the same reference numerals as in FIG. In FIG. 6, when a bending moment MH acts on the steel column base 13, a tensile force QF acts on one of the anchor bolts 5. That is, since the sleeve 8 is inserted into the anchor bolt 5, the anchor bolt 5 is not restrained from the foundation concrete 9, and the tensile force QF acts to peel off the fixing plate 7.

The tensile force QF acts as a result to cause the foundation concrete 9 to break in a cone shape as shown by a broken line. Therefore, in order to counter this, the embedding depth H of the anchor bolt 5 is increased. In general, when the diameter of the shaft portion of the anchor bolt 5 is d, H ≧ 20d. In this case, as the strength of the foundation concrete 9 is lower, the embedding depth H is further increased, and the length of the anchor bolt 5 is also increased.

For this reason, there is a problem that the extension of the anchor bolt 5 becomes large and the degree of fixation of the steel column base 13 decreases. Even if the sleeve 8 is omitted in order to suppress the elongation of the anchor bolt 5 and the adhesion of the anchor bolt 5 to the foundation concrete 9 is to be increased, the anchor bolt 5 is usually formed of round steel and has a smooth surface. Therefore, the adhesive force is unstable. In addition, since the adhesion between the two is broken down with time from the upper end of the anchor bolt 5 and proceeds downward, it is difficult to set the above-mentioned adhesion at the time of design. For this reason, the anchor bolts 5 must be kept in a state of being unrestricted by the sleeve 8 with respect to the foundation concrete 9, and the above-mentioned problems are included.

[0008] In addition to the above problems, the basic concrete 9
Since the size of the rising portion of the base is large, the number of reinforcing bars to be provided in this portion is inevitably increased, and not only the design but also the production of the foundation concrete 9 becomes complicated, and the anchor bolt 5 In addition, the work of positioning and fixing the fixing plate 7 is also complicated, resulting in problems such as an increase in manufacturing cost and an increase in construction period.

Although the anchor bolt 5 is positioned and fixed in the foundation concrete 9, a slight displacement may occur when the foundation concrete 9 is cast. Further, even when the anchor bolt 5 is accurately positioned and fixed, the column base metal 11 may be displaced relative to the anchor bolt 5 due to an assembly error of the steel column 12 and the beam or the like constituting the building.

In order to absorb the displacement or error between the anchor bolt 5 and the column base metal 11 as described above,
Normally, a bolt hole (not shown) for inserting the anchor bolt 5 provided in the column base metal 11 is formed to have a larger diameter than in a general machine structure. Therefore nut 1
A washer 15 is interposed between the metal base 6 and the column base hardware 11 in order to secure contact between the metal base 6 and the base hardware 11. Therefore, there is a problem that the work of fixing and fixing the steel column base 13 to the foundation concrete 9 becomes complicated.

Further, in the exposed steel column base 13 used with the nut 16 exposed, the tightened nut 16 may be loosened, and the fixing and fixing degree of the steel column base 13 may be reduced. Therefore, means for screwing a lock nut above the nut 16 is employed. However, it is customary to use a lock nut having the same specification as the nut 16. When a large number of anchor bolts 5 are used for the steel column base 13, the screwing work of the lock nut is complicated. There is a problem.

In order to prevent the nut 16 from loosening, a spring washer commonly used in a normal mechanical structure is used.
Although it is conceivable to interpose between the pillar base metal 11 and the pillar base metal 11, since the bolt hole for inserting the anchor bolt 5 provided in the column base metal 11 has a large diameter as described above, the spring washer is used. The overlap between the outer circumference of the bolt hole and the outer circumference of the bolt hole is reduced. In an extreme case, the spring washer may sink into the bolt hole, and there is a problem that reliability is low.

[0013] The present invention solves the above-mentioned problems, increases the adhesion of the anchor bolt to the foundation concrete, facilitates the fixing operation, and completely prevents the anchor bolt from loosening. It is an object to provide a fixing structure.

[0014]

In order to solve the above-mentioned problems, in the present invention, a steel column base formed by integrally joining a column base metal to the lower end of a steel column is embedded in a foundation concrete. In the anchoring structure of the steel column base fixed on the foundation concrete via the anchor bolt and the nut screwed to the upper end of the anchor bolt, the anchor bolt is formed by a threaded bar, and the nut has a height dimension. _{H 1 = (3~6) P (} P is the pitch dimension of the section of the screw section rebar) is formed, the height h = 1.5 P or through the spring washer above the nut, form the h <H ₁ The technical means of screwing in the lock nut is adopted.

[0015] In the present invention, the height H ₁ of the nut is less than 3-Way, the number of nodes to be screwed with the screw section reinforcing bars is reduced, the fixing force of the steel column base is insufficient, the nut It is not preferable because the thread of the nut may be crushed during the tightening operation. On the other hand, the nut height H ₁
There exceeds 6P, is only the height dimension H ₁ is large in adversary et undesirably small proportion contributes to the improvement of the clamping force.

Next, since the lock nut is screwed to prevent the nut from loosening, the height of the lock nut may be smaller than that of the nut (h <H ₁ ). If the dimension h is less than 1.5 P, it is not preferable because the restraining force against the nut cannot be sufficiently exerted and the thread may be crushed.

In the present invention, it is preferable that the shape of the projection of the anchor bolt on the vertical plane is U-shaped. By forming in this manner, the steel column base can be fixed by the adhesive force between the upright portion and the foundation concrete and the resistance of the bent portion of the foundation concrete. The mounting depth can be reduced, the degree of fixing of the steel column base and the design of the foundation rising portion are improved, and the installation of the anchoring portion is also simplified.

Next, in the above invention, it is preferable that the bottoms of the anchor bolts intersect in a projected state on a plane. By forming in this way, when a bending moment acts on the steel column base, a tensile force can be applied to only one upright portion of the U-shaped anchor bolt, and the other upright portion can have a tensile force. By applying a compressive force, the anchor bolt can be stabilized.

[0019]

FIG. 1 is a longitudinal sectional view of a main part showing a first embodiment of the present invention, and the same parts are denoted by the same reference numerals as in FIG. In FIG. 1, reference numeral 17 denotes an anchor bolt, which is formed of, for example, an SD490 deformed steel bar (threaded bar) and is embedded in the foundation concrete 9.
The anchor bolt 17 is positioned and fixed to the support member 4 by the nut 6.

Next, the column base metal fitting 11 is formed, for example, in a square shape with a projected contour shape to a plane, and is integrally joined to the lower end of a steel column 12 made of, for example, a square steel pipe by welding to form a steel column base 13. I do. The column base metal 11 is preferably formed of cast steel or forged steel, but may be formed of a thick steel plate.

For example, bolt holes (not shown) are provided at, for example, the corners of the column base hardware 11, and the upper ends of the anchor bolts 17 are inserted into these bolt holes. Then, the nut 16 is screwed to the upper end of the anchor bolt 17 to fix the steel column base 13, and the lock nut 19 is screwed through the spring washer 18 to prevent the nut 16 from loosening.

With the above configuration, when a bending moment MH acts on the steel column base 13 as shown in FIG. 1, for example, a tensile force QF acts on the anchor bolt 17 on the left side. In this case, since the anchor bolt 17 is formed of the threaded bar, the anchor bolt 17 can resist the tensile force QF by the adhesive force with the foundation concrete 9 and fix the steel column base 13. Therefore, the embedding depth can be made smaller than the conventional one shown in FIGS. 5 and 6, and the rising portion of the foundation concrete 9 can be reduced.

In the present invention, the steel column base 1
The rotational rigidity of No. 3 can also be greatly improved. That is, FIG.
In the prior art shown in (1), since the anchor bolt 5 is formed in an unrestricted state over substantially the entire length of the foundation concrete 9 by the sleeve 8, the amount of elongation due to the action of the tensile force QF is large. On the other hand, in the case of the present invention, since the anchor bolts 17 are formed almost completely in the constrained state by the foundation concrete 9, even if the adhesion and peeling occur near the upper end face of the foundation concrete 9, for example, Is small, the amount of elongation due to the action of the tensile force QF remains at a small value.

FIG. 2 is an enlarged longitudinal sectional view of a main part showing the vicinity of the upper end of the anchor bolt 17 in FIG. In FIG. 2, reference numeral 21 denotes a bolt hole, which is provided at, for example, four corners of the column base hardware 11. As shown in FIG.
When the non-shrink mortar 14 is filled and the non-shrinkable mortar 14 is filled, the anchor bolts 17 are formed on the outer periphery of the anchor bolts 17 made of a threaded bar having the outer diameter D and the pitch dimension P of the nodes. Is constrained in the axial direction,
It has a large adhesive force between the foundation concrete 9 and the non-shrink mortar 14.

In this case, the height H ₁ of the nut 16 is
Thereby preventing collapse of the thread, H ₁ = (3~6) to ensure the fastening force P (P is the pitch dimension of the section of the screw section rebar) is preferably formed on. Also lock nut 19
The height h may be formed to h ≧ 1.5 P and h <H _1. With such a configuration, it is possible to secure the fixing power and improve the reliability.

The anchor bolt 17 and the column base metal 11 are connected to the column base metal 11 by grouting the gap between the anchor bolt 17 and the bolt hole 21 with grout through a grout injection hole (not shown). Can be integrated,
The horizontal load QH acting on the column base hardware 11 can be counteracted, and the degree of fixation of the steel column base 13 (see FIG. 1) can be further improved.

Next, the nut 16 and the lock nut 1 will be described.
No. 9 is obtained, for example, by forming a hexagonal bar made of S45C and engraving a female thread corresponding to the threaded joint shown in FIG. 2 in the center. The nut is S45
It can be formed not only by C but also by a casting means of, for example, ductile cast iron or other materials, and also by a forging means.

FIGS. 3 and 4 are a vertical sectional view and a partial cross-sectional plan view of a main part of a second embodiment of the present invention, in which the same parts are designated by the same reference numerals as in FIG. Show.
In FIGS. 3 and 4, the anchor bolt 17 is formed in a U-shape by projecting a vertical plane from the same material as described above, and is embedded in the foundation concrete 9.

With the above configuration, when the bending moment MH acts on the steel column base 13 as shown in FIG. 3, for example, a tensile force QF acts on the left side of the U-shaped anchor bolt 17. In this case, since the anchor bolt 17 is formed in a U-shape by the threaded bar, the anchor bolt 17 resists the tensile force QF by the adhesive force at the upright portion and the resistance of the foundation concrete 9 at the bent portion at the bottom, and The leg 13 can be fixed and the nut 16 can be completely prevented from loosening. Therefore, the embedding depth of the anchor bolt 17 can be further reduced.

In this case, as shown in FIG. 4, it is preferable that the anchor bolts 17 are arranged so that their bottoms intersect when projected onto a plane. In the embodiment of the invention described above, an example in which the steel column is formed by a square steel pipe is described. Of course, the present invention can be applied to a case where three or more pairs of U-shaped anchor bolts are used.

[0031]

Since the present invention has the above-described configuration and operation, the following effects can be obtained.

(1) Since the anchor bolts are formed by the threaded bar, the adhesion to the foundation concrete is increased, the rotational rigidity is improved, and a higher-performance anchoring structure for the steel column base is obtained.

(2) Since the lock nut is screwed through the spring washer above the nut screwed to the anchor bolt, the nut can be completely prevented from loosening, and the securing of the fixing force and the reliability are ensured. Can be improved.

(3) The embedding depth can be greatly reduced as compared with the conventional method using round steel anchor bolts. (4) The degree of fixation of the steel column base and the design of the rising portion of the foundation can be improved, and the construction of the anchoring portion can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view of a main part showing the vicinity of an upper end of an anchor bolt 17 in FIG.

FIG. 3 is a vertical sectional view showing a main part of a second embodiment of the present invention.

FIG. 4 is a partial cross-sectional essential part plan view showing a second embodiment of the present invention.

FIG. 5 is a vertical sectional view of a main part showing an example of a conventional fixing structure for a steel column base.

FIG. 6 is an explanatory view showing a state of an external force acting on a fixing structure of a conventional steel column base.

[Explanation of symbols]

 11 Column base hardware 12 Steel column 16 Nut 17 Anchor bolt

Continued on the front page (72) Inventor Hidenori Tanaka 2-4-2 Toyo, Koto-ku, Tokyo Inside Hitachi Koki Co., Ltd. (72) Kazuyuki Noguchi 2-4-2 Toyo, Toyo, Koto-ku, Tokyo Hitachi Koki Inside the corporation

Claims (3)

[Claims] An anchor bolt embedded in a foundation concrete and a nut screwed to an upper end of the anchor bolt are provided with a steel column base formed by integrally joining a column base hardware to a lower end of the steel column. In the anchoring structure of the steel column base anchored on the foundation concrete through, the anchor bolts are formed by threaded bar,
Height H ₁ = (3~6) P nuts (P is the pitch dimension of the section of the screw section rebar) is formed, the height h = 1.5 P or through the spring washer above the nut, h <fixing structure of steel column base, characterized in that screwed a lock nut formed in H _1. 2. The anchoring structure for a steel column base according to claim 1, wherein a projection shape of the anchor bolt onto a vertical plane is formed in a U-shape. 3. The anchoring structure for a steel column base according to claim 2, wherein the bottoms of the anchor bolts intersect in a projected state on a plane.