JP3381031B2 - Method of designing base plate for steel pipe column and base plate for steel pipe column - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for designing a steel pipe column base plate in an exposed column base construction method and a steel pipe column base plate.

[0002]

2. Description of the Related Art The exposed column pedestal method is a method of fixing a steel column on the foundation concrete by tightening nuts on a base plate welded to the lower end of the steel column and an anchor bolt embedded in the foundation concrete. Is. In recent years, steel pipe column base plates have been required to be smaller and lighter.
Eight-anchor bolt type, in which two anchor bolts are arranged at each of the four corners, has come into use.

FIG. 9 is a side view of a column base fixing structure using such an eight-anchor type steel pipe column base plate, FIG. 10 is a plan view of the column base fixing structure, and FIG. 11 is a square steel pipe in FIG. It is a side view including a partial section of a base plate for pillars. When the fixing structure of the column base is outlined based on FIG. 9 to FIG. 11, 51 is a waste concrete, 5
2 is an anchor frame that is erected on the discarded concrete 51, 53 is a hole-in anchor for fixing the anchor frame 52 to the discarded concrete 51, 54 is provided at the upper end of the anchor frame 52, and an anchor bolt 55 to be described later is provided. It is a fixing plate for fixing.

Reference numeral 55 is an anchor bolt installed on the fixing plate 54, 56 is basic concrete cast on the discarded concrete 51 up to near the upper end of the anchor bolt 55,
7 is a base plate installed on the upper end of the anchor bolt 55, 58 is a nut screwed on the upper end of the anchor bolt 55, 59 is a washer installed between the nut 58 and the base plate 57, and 60 is a base plate on the lower end. 57
Is a welded steel column, and 61 is a grout material placed between the base plate 57 and the foundation concrete 56.

As shown in FIGS. 10 and 11, the base plate 57 has a rectangular outer shape, has a rising portion 57a for welding the steel pipe column 60 in the central portion, and the outside thereof is the outside. It has an inclined surface 57b that is inclined toward one side, and an anchor bolt seat 57c that extends in a diagonal direction and is formed flat, and two bolt holes 57d are formed in the anchor bolt seat 57c across the diagonal line. Has been done.

Further, as shown in FIGS. 12 and 13, the shape of the base plate 57 as described above is mainly the base plate width D and the anchor bolt pitch d1 (except for the rising portion 57a to which the square steel pipe column is welded). The distance between the objects arranged outside), d2 (the distance between those arranged inside), the radius R1 of the anchor bolt seat 57c, the height T1 of the anchor bolt seat, and the height of the sides (the seat is removed from the bottom surface). Height to the highest position) T2.

The base plate width D and the anchor bolt pitches d1 and d2 should be determined so as to withstand the axial force and bending moment acting on the column base. These are the basic concrete strength and the anchor. It may be considered that there is a degree of freedom in design because it depends on the bolt strength. Further, the radius R1 of the anchor bolt seat is determined from the required clearance amount corresponding to the anchor bolt.

On the other hand, a dangerous cross section (check cross section) for designing the height T1 of the anchor bolt seat and the height T2 of the side.
Is an AA cross section and a BB cross section shown in FIG. 14 for the out-of-plane bending due to the tensile force of the anchor bolt,
Also, for out-of-plane bending due to concrete reaction force, B
-B cross section. Here, the AA cross section is a cross section that passes through the corner portion of the rising portion 57a of the base plate 57 and is orthogonal to the diagonal line of the base plate. The BB cross section is a cross section along the rising portion 57a of the inclined surface 57b of the base plate 57.

The following formulas are generally known as the design formulas for T1 and T2. A-A cross section: 2 · Ty · L1 to bending out of the plane due to the tensile force of the anchor bolt ^{<B1 · T1 2/6 ·} f b1 ...... (1) B-B cross section: Area by tensile force of the anchor bolt 2 · Ty · L2 <B2 · T2 2/6 · f b1 ...... the outer bend (2) B-B cross section: 2/3 · Fc against bending out of plane due to concrete reaction force '· L3 ^{2/2 <1 · T2 2} /6 · f b1 ...... (3) where, Ty: tensile force of the anchor bolt f _b1: allowable stress Fc baseplate ': design criteria strength of concrete L1: a-a cross section To the center of the anchor bolt L2: vertical distance from the BB cross section to the center of the anchor bolt L3: distance from the side edge of the base plate to the BB cross section B1: length of the anchor bolt seat 57c in the AA cross section B2: Length of side effective in design in BB cross section

[0010]

According to the above design formula, in the conventional 8-anchor bolt type base plate, L1 generally has a certain length, and B1 <B
Since there is a relationship of 2, T1> T2. Therefore,
The base plate must secure a height that satisfies the above formula as the side height T2 and a value that is greater than T2 as the height T1 of the anchor bolt seat 57c, which increases the thickness of the entire base plate. It was heavy.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for designing a base plate for a steel pipe column and a base plate for a steel pipe column whose thickness can be made as small as possible.

[0012]

A method for designing a base plate for a steel pipe column according to the present invention is a method for designing a base plate for a steel pipe column having two anchor bolt holes at each corner of a rectangular base plate with a diagonal line therebetween. In addition, the center of the anchor bolt hole is set on the virtual line of the dangerous cross section in the direction orthogonal to the diagonal line. Further, the center of the circle when the circle is drawn with the washer radius so as to contact the rising line or the weld line of the steel pipe column is the center of the anchor bolt hole.

A method of designing a steel pipe column base plate having two anchor bolt holes at each corner of a rectangular base plate with a diagonal line interposed therebetween, wherein L2 = DR / 2 (DR : The diameter of the washer) to find T2 that satisfies the following equation (2), compare the value of this T2 with the value of T2 that satisfies the following equation (3), and determine the larger one as the value of T2. And a step of obtaining the value of L1 that satisfies the following expression (1) by substituting the value of T2 determined above as the value of T1 in the following expression (1), and a cross section (B- A line drawn parallel to the (B cross section) outward from the BB cross section by L2 = DR / 2, and a cross section (A-A cross section) that passes through the corner of the rising portion of the base plate and is orthogonal to the diagonal line of the base plate. Parallel to the line A and the intersection with the line separated from the AA section by the above L1 And a step of determining the center of the anchor bolt. 2 · Ty · L1 <B1 · T1 2/6 · f b1 ...... (1) 2 · Ty · L2 <B2 · T2 2/6 · f b1 ...... (2) 2/3 · Fc '· L3 2 / ^{2 <1 · T2 2/6} · f b1 ...... (3) where, T1: height of the anchor bolt bearing T2: the sides of the base plate height Ty: tensile force of the anchor bolt f _b1: a base plate of the allowable stress Fc ′: Design standard strength of concrete L1: Vertical distance from cross section AA to center of anchor bolt L2: Vertical distance from cross section BB to center of anchor bolt L3: Distance from side edge of base plate to cross section BB B1 : Length of seat in AA cross section B2: Length of side in BB cross section

Further, the steel pipe column base plate according to the present invention has two anchor bolt holes at each corner of the rectangular base plate with a diagonal line therebetween, and L2 = DR in the following formula (2). / 2 (DR: Washer diameter)
To obtain T2 that satisfies the following equation (2), compare the value of T2 with the value of T2 that satisfies the following equation (3), and determine the larger one as the value of T2. Substituting the above determined T2 as the value of T1 of L1 that satisfies the following equation (1)
Of the cross section (B-
L2 = DR / 2 outward from the BB cross section in parallel with the (B cross section)
Anchor the intersection of a line drawn apart by a distance from the line AA, which is parallel to the cross-section (A-A cross-section) passing through the corner of the base plate upright and orthogonal to the diagonal of the base plate. It is decided as the center of the bolt. 2 · Ty · L1 <B1 · T1 2/6 · f b1 ...... (1) 2 · Ty · L2 <B2 · T2 2/6 · f b1 ...... (2) 2/3 · Fc '· L3 2 / ^{2 <1 · T2 2/6} · f b1 ...... (3) where, T1: height of the anchor bolt bearing T2: the sides of the base plate height Ty: tensile force of the anchor bolt f _b1: a base plate of the allowable stress Fc ′: Design standard strength of concrete L1: Vertical distance from cross section AA to center of anchor bolt L2: Vertical distance from cross section BB to center of anchor bolt L3: Distance from side edge of base plate to cross section BB B1 : Length of seat in AA cross section B2: Length of side in BB cross section

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Before describing specific embodiments, a method of designing a base plate that reduces the thickness of the base plate as much as possible will be described by taking the above-mentioned design formula as an example.

[0016] A-A cross section: 2 · Ty · L1 to bending out of the plane due to the tensile force of the anchor bolt ^{<B1 · T1 2/6 ·} f b1 ...... (1) B-B cross section: tensile anchor bolt 2 · Ty · L2 <B2 · T2 2/6 · f b1 ...... against bending plane by the force (2) B-B cross section: 2/3 · Fc against bending out of plane due to concrete reaction force ^{'· L3 2/2 <1} · T2 2/6 · f b1 ...... (3) where, Ty: tensile force of the anchor bolt f _b1: allowable stress Fc baseplate': design criteria strength of concrete L1: a -Vertical distance from cross section A to center of anchor bolt L2: vertical distance from cross section BB to center of anchor bolt L3: distance from side edge of base plate to cross section BB B1: length of seat in cross section AA B2: Length of side in BB cross section

In the above equation, in order to make the thickness of the base plate as small as possible, T1 and T2 should be minimized. For that purpose, the position of the anchor bolt should be set so that L1 and L2 are minimized. First, the minimum value of L1 can be set to L1 = 0. To set L1 = 0, the center of the anchor bolt may be set on the AA cross section. Then, in order to satisfy the condition of L1 = 0 and minimize L2, when a circle is drawn with a washer radius with a center on the line AA, when the circle touches the rising part of the base plate, The center of the circle should be the center of the anchor bolt.

With the above arrangement, the left side of (1) in the design formula becomes 0, and the value of T1 can be freely determined, and the value of T1 is determined by formula (2) or (3). It can be the same as the value of T2. It should be noted that the value of T2 must be a large value determined by both equation (2) or equation (3). If the base plate is designed based on T1 and T2 obtained as described above, the base plate having the minimum thickness can be designed.

FIG. 1 is an illustration of a specific method for determining the anchor bolt position based on the above design method.
Shows an example in which the rising portion 57a of the base plate 57 does not have a taper portion. Hereinafter, a method of determining the anchor bolt position for minimizing the thickness of the base plate will be described with reference to FIG. 1. A virtual line 1 of the dangerous cross section A-A is drawn. 2. An imaginary line 3 having a construction margin e is drawn outside the rising portion 57a. 3. The centers 0 ₁ and 0 ₂ are on the virtual line 1 and the virtual line 3
A circle with a radius of DR / 2 (DR: washer diameter)
Two pieces are drawn on each side of the diagonal line of the base plate 57. 4. Radius R1 (R around the center 0 _1, 0 ₂ of the circle
1: Radius of anchor bolt seat) Draw a circle. The centers 0 ₁ and 0 ₂ of the above circles are the positions of the anchor bolts that minimize the base plate thickness.

Embodiment 2. FIG. 2 is an explanatory diagram of the second embodiment of the present invention. The second embodiment is an example in which the rising portion 57a is provided with a taper. In this example, the construction allowance e is taken outside the lower end of the taper. Others are the same as those in the first embodiment.

In the first and second embodiments described above, the construction allowance e is secured, but this is in consideration of the construction workability and is not necessary as an invention.

Embodiment 3. In the above-described first and second embodiments, an example in which L1 is set to 0 has been shown, but it is not always necessary to set L1 to 0 in order to achieve the object of the present invention. The position of the anchor bolt may be set so that the designed plate thickness is less than or equal to the designed plate thickness of the dangerous cross section BB parallel to the side.

Specifically, in the equation (2) shown in the first embodiment, L2 = DR / 2 (DR: diameter of washer) is set to obtain T2 satisfying the equation (2), and the value of this T2 is obtained. Is compared with the value of T2 that satisfies the expression (3), and the larger value is determined as the value of T2. Then, the value of T2 determined above is substituted as the value of T1 in equation (1) to obtain the value of L1 that satisfies equation (1). Then, a line drawn parallel to the line BB from the line BB outwardly separated by L2 = DR / 2 and A-
An intersection with a line separated from the line AA by L1 in parallel with the line A is determined as the center of the anchor bolt.

As described above, according to this embodiment, L1
> 0 and a larger bending moment can be applied to the column base than when L1 = 0.

When the construction allowance e is taken, L2 = DR / 2 + e may be set in the above procedure.

[0026]

EXAMPLE FIGS. 3 to 8 are explanatory views of a specific example designed based on the first embodiment, and FIGS. 3 to 5 show a type provided with an anchor bolt seat, and FIG. ~ Fig. 8 shows a flat plate type without an anchor bolt seat.
The same parts as those in FIGS. 0 to 14 are designated by the same reference numerals.

FIG. 3 shows an example in which, when a circle having a radius R1 is drawn, the outer circumference of the circle is inside the outer peripheral line of the base plate 57. In other words, the width of the base plate 57 is the seat of the anchor bolt. It will be more outside. Moreover, what is shown in FIG. 4 is an example in which the outer periphery of the circle is in contact with the outer peripheral line of the base plate 57 when a circle of radius R1 is drawn, in other words, the width of the base plate 57 is in contact with the seat of the anchor bolt. is there. Furthermore, what is shown in FIG. 5 is an example in which the outer circumference of the circle is outside the outer peripheral line of the base plate 57 when a circle of radius R1 is drawn, in other words, the seat of the anchor bolt projects outside the base plate 57. To do.

Further, in the structure shown in FIG. 6, the width of the base plate 57 is outside the necessary clearance of the anchor bolt. Further, as shown in FIG. 7, the width of the base plate 57 is in contact with the necessary edge of the anchor bolt. Further, in the structure shown in FIG. 8, the width of the base plate 57 is inside the required clearance of the anchor bolt.

The flat plate type as shown in FIGS. 6 to 8 is disadvantageous in using more material than the type having the anchor bolt seat shown in FIGS. 3 to 5, but Since the shape is simple, there is an advantage that it is easy to manufacture. Further, according to the present invention, since the entire thickness can be reduced, the material of the flat plate type can be reduced as compared with the conventional design, and the weight and cost can be reduced.

In the above example, the base plate having a rising portion has been described as an example, but the present invention is not limited to this, and a plate-shaped base plate without a rising portion is also described above. The anchor bolt pitch can be determined based on the above concept. In this case, the position of the weld line of the steel pipe column corresponds to the outer peripheral line of the rising portion.

Further, in the above-mentioned example, the base plate for the rectangular steel pipe column having a rectangular rising portion has been described as an example, but the present invention is not limited to this, and a circular steel pipe having a round rising portion. It can also be applied to pillars.

[0032]

Since the present invention is constructed as described above, it has the following effects.

Since the center of the anchor bolt hole is set on the virtual line of the dangerous cross section in the direction orthogonal to the diagonal line, the dangerous cross section in the direction orthogonal to the diagonal line can be avoided in design, and the entire base plate can be avoided. The plate thickness can be reduced.

Further, by designing a circle of the washer radius so as to be in contact with the rising line or the weld line of the steel pipe column, the center of the circle is set as the center of the anchor bolt hole, thereby designing a dangerous cross section parallel to the side of the base plate. The thickness of the upper plate can be reduced, and the thickness of the entire base plate can be reduced.

[0035]

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of another embodiment of the present invention.

FIG. 3 is an explanatory diagram of an embodiment of the present invention.

FIG. 4 is an explanatory diagram of another embodiment of the present invention.

FIG. 5 is an explanatory diagram of another embodiment of the present invention.

FIG. 6 is an explanatory diagram of another embodiment of the present invention.

FIG. 7 is an explanatory diagram of another embodiment of the present invention.

FIG. 8 is an explanatory diagram of another embodiment of the present invention.

FIG. 9 is a side view of a column base fixing structure using a conventional 8-anchor type rectangular steel pipe column base plate.

FIG. 10 is a plan view of a column base fixing structure using a conventional 8-anchor type rectangular steel pipe column base plate.

11 is a side view including a partial cross section of the square steel pipe column base plate in FIG. 9. FIG.

FIG. 12 is an explanatory diagram of dimensions of each part of a conventional base plate for rectangular steel pipe columns.

FIG. 13 is an explanatory diagram of the dimensions of each part of the conventional base plate for square steel pipe columns.

FIG. 14 is an explanatory view of positions of anchor bolt holes of a conventional base plate for square steel pipe columns.

[Explanation of symbols]

1 Virtual line of dangerous section A-A 3 Virtual line of construction margin e 57 Base plate 57a Rise

─────────────────────────────────────────────────── ─── Continuation of front page (56) Bibliography Sho 61-161307 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) E04B 1/24 E02D 27/00

Claims (4)

(57) [Claims] 1. A method for designing a base plate for a steel pipe column having two anchor bolt holes at each corner of a rectangular base plate with a diagonal line sandwiched therebetween, wherein the above-mentioned method is provided on a virtual line of a dangerous cross section in a direction orthogonal to the diagonal line. A method for designing a base plate for a steel pipe column, characterized in that the center of the anchor bolt hole is set. 2. The steel pipe column according to claim 1, wherein the center of the circle when the circle is drawn with the washer radius so as to contact the rising portion or the weld line of the steel pipe column is the center of the anchor bolt hole. How to design a base plate. 3. A method for designing a base plate for a steel pipe column having two anchor bolt holes at each corner of a rectangular base plate with a diagonal line sandwiched therebetween, wherein L2 = DR / 2 (DR : Washer diameter) and find T2 that satisfies the following formula (2).
And the value of T2 satisfying the following formula (3) is compared, and the larger one is determined as the value of T2, and the value of T2 determined above is substituted as the value of T1 in the following formula (1). Then, the step of obtaining the value of L1 that satisfies the following formula (1) and the step of separating L2 = DR / 2 outward from the BB section in parallel with the section (BB section) along the rising portion of the base plate are performed. A parallel to the drawn line and the cross section (A-A cross section) that passes through the corner portion of the rising edge of the base plate and is orthogonal to the diagonal line of the base plate.
-A step of deciding an intersection with a line separated from the section A by L1 as the center of the anchor bolt, the method for designing a steel pipe column base plate. 2 · Ty · L1 <B1 · T1 2/6 · f b1 ...... (1) 2 · Ty · L2 <B2 · T2 2/6 · f b1 ...... (2) 2/3 · Fc '· L3 2 / ^{2 <1 · T2 2/6} · f b1 ...... (3) where, T1: height of the anchor bolt bearing T2: the sides of the base plate height Ty: tensile force of the anchor bolt f _b1: a base plate of the allowable stress Fc ′: Design standard strength of concrete L1: Vertical distance from A-A section to center of anchor bolt L2: Vertical distance from BB section to center of anchor bolt L3: Distance from side edge of base plate to BB section B1 : Length of seat in AA cross section B2: Length of side in BB cross section 4. A steel pipe column base plate having two anchor bolt holes at each corner of a rectangular base plate with a diagonal line sandwiched therebetween, wherein L2 = DR / 2 (DR: washer (Diameter) to find T2 that satisfies the following equation (2),
And the value of T2 satisfying the following formula (3) are compared, the larger one is determined as the value of T2, and the determined T2 of the above is substituted as the value of T1 of the following formula (1), The value of L1 that satisfies the following formula (1) is determined, and L2 = D outward from the BB section parallel to the section (BB section) along the rising portion of the base plate.
A line drawn apart by R / 2 and a section (AA cross section) which passes through the corner of the base plate at the rising portion and is orthogonal to the diagonal line of the base plate.
A base plate for a steel pipe column, characterized in that it is determined by setting the intersection with a line separated by the center of the anchor bolt. 2 · Ty · L1 <B1 · T1 2/6 · f b1 ...... (1) 2 · Ty · L2 <B2 · T2 2/6 · f b1 ...... (2) 2/3 · Fc '· L3 2 / ^{2 <1 · T2 2/6} · f b1 ...... (3) where, T1: height of the anchor bolt bearing T2: the sides of the base plate height Ty: tensile force of the anchor bolt f _b1: a base plate of the allowable stress Fc ′: Design standard strength of concrete L1: Vertical distance from A-A section to center of anchor bolt L2: Vertical distance from BB section to center of anchor bolt L3: Distance from side edge of base plate to BB section B1 : Length of seat in AA cross section B2: Length of side in BB cross section