JP2002339455A - Method and device for evaluating exposed type fixed column base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of an exposed type fixed column base by computing an optimum rotational spring constant even when using a threaded bar formed of ordinary steel, as an anchor bolt. SOLUTION: In this method for evaluating the exposed type fixed column base, the exposed type fixed column base for fixing a base plate to which a steel column of a building is jointed, to a footing concrete foundation by the threaded anchor bolt, is evaluated using the rotational spring constant KBS of the column base in an expression: KBS=M/θ... (1) expressed by the ratio of bending moment M of the column base to the rotation angle θ of the base plate, and the bending moment M of the column base and the rotation angle θof the base plate are expressed by M=C(DBS/2-k2 xn )+T(DBS/2-dt ) and θ=(δT+δC)/(DBS-k2 xn -dt ).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaluation method and an evaluation apparatus for an exposed fixed column base, and more particularly, to an exposed type fixed column base used for fixing a steel column of a building to a concrete foundation. And an evaluation device.

[0002]

2. Description of the Related Art Exposed fixed column bases are advantageous in terms of construction time compared to embedded column bases. Generally, exposed fixed column bases fix a base plate to the lower part of a steel column, and attach the base plate to the base plate. The structure is fixed to the concrete foundation via high-strength anchor bolts.

Since the base plate of the column base receives an axial compressive force and bending moment from the steel column side, for example, in a state where the thread portion of the tension side anchor bolt protrudes from the lower surface of the base plate, the base plate is rotated with the bending rotation of the column base. Therefore, it is important to determine the optimal rotation spring constant of the exposed fixed column base because problems such as the thread portion being subjected to local bending and tensile deformation may occur.

The rotation spring constant K of these exposed fixed column bases
_In calculating the _BS , the following equation (51) is used (refer to the Japan Building Center, 1977 edition of the Building Structure Regulations).

[0005] In _{K BS = [E · n t} · A b (d t + d c) 2] / 2l b ...... (105) This _{equation, E, n t, A b} , l b, d t, d _c is as follows.

[0006] E: Young's modulus of the anchor bolt _{^{(kN / mm 2) n t}} : number of tension side anchor bolt A _b: cross-sectional area of one anchor bolt (mm ²⁾ l _b: length of the anchor bolt (mm ) d _t: distance to the centroid of the tension side anchor bolt sectional group than the pillar sectional view heart (mm) d _c: distance to column flange outer edge of the compression side of the pillar sectional view heart (mm)

[0007]

[SUMMARY OF THE INVENTION However, the formula for calculating the rotational spring constant K _BS in the conventional exposure fixation column base can not be applied when using Nejifushi rebar having adhered to the anchor bolt. In this formula, the design axial force of the column, the compressive strength of the footing concrete, the width of the footing, the depth of the footing, the height of the footing, the eccentricity of the footing and the base plate, the tensile strength of the anchor steel, the anchor diameter, the anchor bolt The factors such as the spacing of the bolts and the tightening force of the screw and the nut of the anchor bolt are not taken into account. Therefore, an optimal rotation spring constant cannot be obtained.

[0008] Japanese Patent Publication No. 2984251, which is a related prior art, discloses that an anchor bolt is arranged at four corners of a base plate of an exposed fixed column base, and an anchor is used by using a metal to fill a bolt clearance of a bolt hole of the base plate. The conditional expression that restricts the bending deformation of the bolt within the thickness of the base plate and does not cause the base plate to stand up, that is, when the rotation angle of the column base is θ ₀ and the local deformation angle of the base plate is θ ₁ , θ ₁ ≧ 0.8θ
An exposed fixed column base that determines the arrangement position of the anchor bolts, the rigidity and the proof stress of the anchor bolts, and the thickness of the base plate based on the equation ₀ is described.

However, the conditional expression in the invention described in Japanese Patent Publication No. 2984251 cannot be used unless the attachment of the anchor bolt is cut, and the cost is increased only by the details for cutting the attachment. In addition, since the sinking deformation of the concrete on the compression side of the base plate of the footing is neglected, the rotational rigidity is smaller than the actual one, and the evaluation on the dangerous side is given. Further, the higher the footing depth, the lower the rotational rigidity, giving a value on the dangerous side. Furthermore, the initial tightening of the anchor bolt is stated, but since the equation does not include a term for the tightening force, the value of the rotational rigidity is virtually undefined.

The present invention has been made in order to solve the above-mentioned problems, and calculates an optimum rotation spring constant even when a screw reinforcing bar made of ordinary steel is used as an anchor bolt, thereby reducing the cost of an exposed fixed column base. An object of the present invention is to provide an evaluation method and an evaluation device for an exposed fixed column base that can be reduced.

[0011]

Means for Solving the Problems In order to achieve the above object, an invention according to claim 1 is an exposure type fixing method for fixing a base plate to which a steel column of a building is joined to a footing concrete foundation with an anchor bolt having a threaded stub. An evaluation method of an exposed fixed column base for evaluating a column base using a rotation spring constant K _BS of a column base expressed by the following equation (106) expressed by a ratio of a bending moment M of the column base to a rotation angle θ of the base plate. Where, K _BS = M / θ (106) The bending moment M of the column base and the rotation angle θ of the base plate are calculated as follows: M = C (D _BS / 2−k ₂ × _n ) + T (D _BS / 2−d _t) is characterized by evaluating the ...... (107) θ = (δ T + δ C) / (D BS -k 2 x n -d t) ...... (108).

Here, k ₂ x _n = x _n / 3 (109) x _n = 4C / (3B _BS · σ _C ) (110) C = N + T (111) T = a _t · E _S · _S ε _y …… (112) δ _C = I ₁ …… (113) I ₁ = C / [E _C · (B _BS −W)] × log [(z ₁ + W) B _BS / [( z ₁ + B _BS ) W]] …… (114) W = C / (B _BS / σ _C ) …… (115)

[0013]

[Table 5]

[0014] _{H = D F -D BS + 2k} 2 x n -W ...... (116) H 1 = B F -B BS -2e y ...... (117) H 2 = B F -B BS + 2e y ...... ( 118) σ _C = E _C · ε _C …… (119) δ _T = [H _m + T _BS + V _F + m · p _m / 3] _S ε _y …… (120) I ₀ = [(a _t + a _C ) E _S · _S ε ₀ / (B _BS −D _BS )] × log [(H _F / 2 + D _BS ) B _BS / [(H _F / 2 + B _BS ) D _BS ]] …… B _BS −D _BS ≠ 0 time _{= (a t + a C)} E S · S ε 0 · H F / [(H F + 2B BS) D BS] when ...... (121) of the _{...... B BS -D BS = 0 m} = 2a t1 · S σ _y / (a _m / _Q σ _sy ) −1 …… (122) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (123) ψ _i = 2 [π · Rψ + (i−1) s] / i …… (124) ψ ₁ = 2π · Rψ …… (125) Rψ = [a _t1 (1 + _S σ _y / F _C ) / π] ^1/2 …… (126) _Q1 σ _sy = 2F _C …… (127) δ _C ^* = (x _n ^* -k ₂ x _n ^* ) δ _T / (D _BS / 2-d _t ) …… (128) N: Designed column compression axial force F _C : Footing concrete the design strength E _C: modulus of elasticity of the footing concrete H _F: footing height V _F: thickness suffers the top concrete footing B _F: footing in the depth direction (M direction) dimension B _BS: depth of the base plate T _BS: The thickness of the base plate D _BS: because of the base plate d _t: distance from the edge of the base plate to the tension side anchor bolt core D _F / 2: distance from the base plate core as measured in D _BS direction about the compression side footing to the edge e _y: B eccentricity distance from the base plate core as measured in the _BS direction to the core of the footing a _t1: tension side anchor bolt 1 Cross-sectional area _S σ _y : Yield strength of cross-sectional area of one tension-side anchor bolt E _S : Elastic modulus _S of tension-side anchor bolt _S ε _y : Yield strain of tension-side anchor bolt a _m : Shaft of anchor bolt thread direction projected Bearing area p _m: pitch H _m of Nejifushi anchor bolts: fixing nut height s: center of the anchor bolt spacing a _t: the total cross-sectional area of the tension-side anchor bolt a _C: The total cross-sectional area _S epsilon ₀ of the reduced side anchor bolts: nut tightening when distortion i: Conditions [s ≦ 2Rψ] (the i = 1 when not satisfied) the total number of a group of tension-side anchor bolt satisfying the second aspect of the present invention Is an exposed fixed column base for fixing a base plate to which a steel column of a building is joined to a footing concrete foundation with an anchor bolt having a threaded bar, expressed by a ratio between a bending moment M of the column base and a rotation angle θ of the base plate. In the evaluation method of the exposed fixed column base evaluated using the rotation spring constant K _BS of the column base of the following formula (129), K _BS = M / θ (129) The bending moment M of the column base and the base plate M = C (D _BS / 2−k ₂ × _n ) + T (D _BS / 2−d _t ) (130) θ = (δ _T + δ _C ) / (D _BS −k ₂ x _n −d _t )... (131)

Here, k ₂ x _n = x _n / 3 (132) x _n = 4C / (3B _BS · σ _C ) ··· (133) C = N + T ··· (134) T = a _t · E _S · _S ε _y …… (135) δ _C = I ₁ + I ₂ + I ₃ + I ₄ + I ₅ + I ₆ …… (136) I ₁ = C / [E _C · (B _BS −W)] × log [ (z ₁ + W) B _BS / [(z ₁ + B _BS ) W]] …… (137) I ₂ = 2C / [E _C · (B _BS −2W)] × log [(z ₃ + 2W) (z ₂ + B _BS ) / [(z ₃ + B _BS ) (z ₂ + 2W)]] ... (138) I ₃ = 2C / [E _C · (W−2B _BS )] × log [(z ₃ + 2B _BS ) ( z ₂ + W) / [(z ₃ + W) (z ₂ + 2B _BS )]] ... (1 39) I ₄ = C / [E _C · (B _BS −W)] × log [(z ₅ + 2W) ( z ₄ + 2B _BS ) / [(z ₅ + 2B _BS ) (z ₄ + 2W)]]… (1 40) I ₅ = C / (E _C · B _F ) × log [(z ₅ + W) / (z ₄ + W)] …… (141) I ₆ = 2C / (E _C · B _F ) × log [(H _F / 2 + 2W) / (z ₆ + 2W)] …… (142) W = C / (B _BS / σ _C ) …… (143)

[0016]

[Table 6]

H = D _F −D _BS + 2k ₂ x _n −W (144) H ₁ = B _F −B _BS −2e _y (145) H ₂ = B _F −B _BS + 2e _y. 146) σ _C = E _C · ε _C …… (147) δ _T = [− δ ₀ + H _m + T _BS + V _F + m · p _m / 3] _S ε _y …… (148) δ ₀ = I ₀ + [ H _m + T _BS + V _F + m · p _m / 3] _S ε ₀ …… (149) I ₀ = [(a _t + a _C ) E _S · _S ε ₀ / (B _BS −D _BS )] × log [( _{H F / 2 + D BS)} B BS / [(H F / 2 + B BS) D BS] ] ...... B _BS -D when _{BS ≠ 0 = (a t +} a C) E S · S ε 0 · H F / [ (H _F + 2B _BS ) D _BS ] …… When B _BS −D _BS = 0 …… (150) m = 2a _t1 · _S σ _y / (a _m / _Q σ _sy ) −1 …… (151) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (152) ψ _i = 2 [π · Rψ + (i−1) s] / i …… (153) ψ ₁ = 2π · Rψ …… (154 ) Rψ = [a _t1 (1+ _S σ _y / F _C ) / π] ^1/2 …… (155) _Q1 σ _sy = 2F _C …… (156) δ _C ^* = (x _n ^* -k ₂ x _{n ^{*) δ T / (D BS}} / 2-d t) ...... (157) N: design column compressive axial force F _C: design strength footing concrete E _C: modulus of elasticity of the footing concrete H _F: Fuchi Height V _F of the grayed: wearing thickness of the top concrete footing B _F: footing in the depth direction (M direction) dimension B _BS: depth of the base plate T _BS: The thickness of the base plate D _BS: because of the base plate d _t : distance between the edge of the base plate to the tension side anchor bolts core D _F / 2: distance from D _BS direction to the base plate core as measured for the compressed side footing to the edge e _y: footing base plate core as measured in the B _BS direction eccentricity distance to the core a _t1: the cross-sectional area of the tension-side anchor bolt one _S sigma _y: yield strength of the cross-sectional area of the tension-side anchor bolt one E _S: elastic modulus of the tension side anchor bolt _S epsilon _y: tensile yield strain of the side anchor bolt a _m: axial projection of Nejifushi anchor bolts Bearing area p _m: pitch H _m of Nejifushi anchor bolts: fixing nut height s: anchor Bol Center distance a _t of: the total cross-sectional area of the tension-side anchor bolt a _C: compression side anchor the total cross-sectional area of the bolt _S epsilon _0: nut tightening when distortion i: Conditions [s ≦ 2Rψ] group of the tension side anchor bolt satisfying The total number (i = 1 when not satisfied) of the invention of claim 3 is an exposed fixed column base for fixing a base plate to which a steel column of a building is joined to a footing concrete foundation with an anchor bolt having a threaded thread, An evaluation apparatus for an exposed fixed column base evaluated using a rotation spring constant K _BS of the column base expressed by the following formula (158), which is expressed by the ratio of the bending moment M of the column base to the rotation angle θ of the base plate, K _BS = M / θ …… (158) The bending moment M of the column base and the rotation angle θ of the base plate are calculated as follows: M = C (D _BS / 2−k ₂ × _n ) + T (D _BS / 2−d _t ) (159) θ = (δ _T + δ _C ) / (D _BS −k ₂ x _n −d _t ) (160)

Here, k ₂ x _n = x _n / 3 (161) x _n = 4C / (3B _BS · σ _C ) ··· (162) C = N + T ··· (163) T = a _t · E _S · _S ε _y …… (164) δ _C = I ₁ …… (165) I ₁ = C / [E _C · (B _BS −W)] × log [(z ₁ + W) B _BS / [( z ₁ + B _BS ) W]] …… (166) W = C / (B _BS / σ _C ) …… (167)

[0019]

[Table 7]

H = D _F −D _BS + 2k ₂ x _n −W (168) H ₁ = B _F −B _BS −2e _y (169) H ₂ = B _F −B _BS + 2e _y. 170) σ _C = E _C · ε _C …… (171) δ _T = [H _m + T _BS + V _F + m · p _m / 3] _S ε _y …… (172) I ₀ = [(a _t + a _C ) E _S · _S ε ₀ / (B _BS −D _BS )] × log [(H _F / 2 + D _BS ) B _BS / [(H _F / 2 + B _BS ) D _BS ]] …… B _BS −D _BS ≠ 0 time _{= (a t + a C)} E S · S ε 0 · H F / [(H F + 2B BS) D BS] ...... B BS when ... (173) of _{-D BS = 0 m = 2a t1} · S σ _y / (a _m / _Q σ _sy ) −1 …… (174) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (175) ψ _i = 2 [π · Rψ + (i−1) s] / i …… (176) ψ ₁ = 2π · Rψ …… (177) Rψ = [a _t1 (1 + _S σ _y / F _C ) / π] ^1/2 …… (178) _Q1 σ _sy = 2F _C …… (179) δ _C ^* = (x _n ^* -k ₂ x _n ^* ) δ _T / (D _BS / 2-d _t ) …… (180) N: Design column compression axial force F _C : Footing concrete the design strength E _C: modulus of elasticity of the footing concrete H _F: footing height V _F: thickness suffers the top concrete footing B _F: footing in the depth direction (M direction) dimension B _BS: depth of the base plate T _BS: The thickness of the base plate D _BS: because of the base plate d _t: distance from the edge of the base plate to the tension side anchor bolt core D _F / 2: distance from the base plate core as measured in D _BS direction about the compression side footing to the edge e _y: B eccentricity distance from the base plate core as measured in the _BS direction to the core of the footing a _t1: tension side anchor bolt 1 Cross-sectional area _S σ _y : Yield strength of cross-sectional area of one tension-side anchor bolt E _S : Elastic modulus _S of tension-side anchor bolt _S ε _y : Yield strain of tension-side anchor bolt a _m : Shaft of anchor bolt thread direction projected Bearing area p _m: pitch H _m of Nejifushi anchor bolts: fixing nut height s: center of the anchor bolt spacing a _t: the total cross-sectional area of the tension-side anchor bolt a _C: The total cross-sectional area _S epsilon ₀ of the reduced side anchor bolts: nut tightening when distortion i: Conditions [s ≦ 2Rψ] total number of a group of tension-side anchor bolt satisfying (when not met i = 1) The invention of claim 4 Is an exposed fixed column base for fixing a base plate to which a steel column of a building is joined to a footing concrete foundation with an anchor bolt having a threaded bar, expressed by a ratio between a bending moment M of the column base and a rotation angle θ of the base plate. In the evaluation device for the exposed fixed column base evaluated using the rotation spring constant K _BS of the column base of the following formula (181), K _BS = M / θ (181) The bending moment M of the column base and the base plate M = C (D _BS / 2−k _{2 xn} ) + T (D _BS / 2−d _t ) (182) θ = (δ _T + δ _C ) / (D _BS −k ₂ x _n −d _t )... (183)

Here, k ₂ x _n = x _n / 3 (184) x _n = 4C / (3B _BS · σ _C ) (185) C = N + T (186) T = a _t · E _S · _S ε _y ··· (187) δ _C = I ₁ + I ₂ + I ₃ + I ₄ + I ₅ + I ₆ ··· (188) I ₁ = C / [E _C · (B _BS −W)] × log [ (z ₁ + W) B _BS / [(z ₁ + B _BS ) W]] …… (189) I ₂ = 2C / [E _C · (B _BS −2W)] × log [(z ₃ + 2W) (z ₂ + B _BS ) / [(z ₃ + B _BS ) (z ₂ + 2W)]] ... (1 90) I ₃ = 2C / [E _C · (W−2B _BS )] × log [(z ₃ + 2B _BS ) ( z ₂ + W) / [(z ₃ + W) (z ₂ + 2B _BS )]] ... (191) I ₄ = C / [E _C · (B _BS −W)] × log [(z ₅ + 2W) ( z ₄ + 2B _BS ) / [(z ₅ + 2B _BS ) (z ₄ + 2W)]]… (1 92) I ₅ = C / (E _C · B _F ) × log [(z ₅ + W) / (z ₄ + W)]… (193) I ₆ = 2C / (E _C · B _F ) × log [(H _F / 2 + 2W) / (z ₆ + 2W)] …… (194) W = C / (B _BS / σ _C ) …… (195)

[0022]

[Table 8]

H = D _F −D _BS + 2k ₂ x _n −W (196) H ₁ = B _F −B _BS −2e _y (197) H ₂ = B _F −B _BS + 2e _y. 198) σ _C = E _C · ε _C … (199) δ _T = [− δ ₀ + H _m + T _BS + V _F + m · p _m / 3] _S ε _y …… (200) δ ₀ = I ₀ + [ _{H m + T BS + V F} + m · p m / 3] S ε 0 ...... (201) I 0 = [(a t + a C) E S · S ε 0 / (B BS -D BS)] × log [( _{H F / 2 + D BS)} B BS / [(H F / 2 + B BS) D BS] ] ...... B _BS -D when _{BS ≠ 0 = (a t +} a C) E S · S ε 0 · H F / [ (H _F + 2B _BS ) D _BS ] …… When B _BS −D _BS = 0 …… (202) m = 2a _t1 · _S σ _y / (a _m / _Q σ _sy ) −1 …… (203) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (204) ψ _i = 2 [π · Rψ + (i−1) s] / i …… (205) ψ ₁ = 2π · Rψ …… (206 ) Rψ = [a _t1 (1+ _S σ _y / F _C ) / π] ^1/2 …… (207) _Q1 σ _sy = 2F _C …… (208) δ _C ^* = (x _n ^* -k ₂ x _{n ^{*) δ T / (D BS}} / 2-d t) ...... (209) N: design column compressive axial force F _C: design strength footing concrete E _C: modulus of elasticity of the footing concrete H _F: Fuchi Height V _F of the grayed: wearing thickness of the top concrete footing B _F: footing in the depth direction (M direction) dimension B _BS: depth of the base plate T _BS: The thickness of the base plate D _BS: because of the base plate d _t : distance between the edge of the base plate to the tension side anchor bolts core D _F / 2: distance from D _BS direction to the base plate core as measured for the compressed side footing to the edge e _y: footing base plate core as measured in the B _BS direction eccentricity distance to the core a _t1: the cross-sectional area of the tension-side anchor bolt one _S sigma _y: yield strength of the cross-sectional area of the tension-side anchor bolt one E _S: elastic modulus of the tension side anchor bolt _S epsilon _y: tensile yield strain of the side anchor bolt a _m: axial projection of Nejifushi anchor bolts Bearing area p _m: pitch H _m of Nejifushi anchor bolts: fixing nut height s: anchor Bol Center distance a _t of: the total cross-sectional area of the tension-side anchor bolt a _C: compression side anchor the total cross-sectional area of the bolt _S epsilon _0: nut tightening when distortion i: Conditions [s ≦ 2Rψ] group of the tension side anchor bolt satisfying According to the inventions of claims 1 to 4, since this formula is a design formula that can be used for a general reinforcing rod with an anchor bolt or the like, the cost is reduced. It is possible to reduce the expansion, suppress the elongation of the anchor bolt, and improve the rotational rigidity. In addition, since the sinking deformation of the compression side concrete of the base plate is strictly evaluated and the initial tightening of the anchor bolt is also appropriately evaluated, a more accurate rotation spring constant value can be obtained. Therefore,
In the exposed fixed column base, the optimum rotation spring constant can be calculated even when the screw reinforcing bar made of ordinary steel is used as the anchor bolt, and the cost can be reduced.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 and 2 show an example of an exposed fixed column base 10 according to an embodiment of the present invention. The footing 12 of the exposed fixed column base 10 serves as a concrete foundation for supporting the column 18, and the footing 12 has a base plate 14 joined to a lower portion of the column 18.
Are fixed via an anchor bolt 16 having a screw thread, and the anchor bolt 16 is fastened by a nut 20.

FIG. 1A shows a state of the footing 12 before tightening the nut 20 to the anchor bolt 16, and FIG. 1B shows a state of the footing 12 after tightening the nut 20 to the anchor bolt 16. ing. FIG.
In (A) and (B), the upper surface of the footing 12 before tightening the nut 20 is called a free surface and is indicated by a two-dot chain line X.

In evaluating such an exposed fixed column base 10, the rotational spring constant K _{BS of the} exposed fixed column base is evaluated.
Is defined from the bending moment M of the column base to be described later and the rotation angle θ of the base plate 14 as in the following expression (210). K _BS = M / θ (210) As shown in FIG. 2, after the nut 20 is tightened, the base plate 14 receives a column axial compressive force N and a column base bending moment M. The column base bending moment M is defined as in the following equation (212). _{M = C (D BS / 2} -k 2 x n) + T (D BS / 2-d t) ...... (212) Note that, D _BS is because of the base plate, k ₂ x _n is the compression-side base plate 14 distance from the edge to a position where the action of the compression force C, d _t is the distance until the tension side anchor bolt core from the edge of the base plate. Further, C is a compression resultant force, and the balance of the vertical force, that is,
This is the sum of the column axial compressive force N and the tensile resultant force T. Therefore,
C can be expressed as in equation (213).

C = N + T (213) In this equation, the tensile resultant force T is defined as the anchor bolt yield tension. Therefore, T can be expressed as in equation (214).

[0029] _{T = a t · E S ·} S ε y ...... (214) a t: yield strength of the cross-sectional area of the anchor bolt E _S: the yield strain of the anchor bolt _{S ε y:} the yield strain of the tension side anchor bolt also , The rotation angle θ of the base plate 14 as shown in FIG.
Is the amount of depression δ _C of the compression side base plate 14 with respect to the core of the footing 12 and the tension side anchor bolt 16
From the top displacement [delta] _T of, are defined as the following (215) below.

Θ = (δ _T + δ _C ) / (D _BS −k ₂ x _n −d _t ) (215) In the following, each of the terms M and θ is examined, and the rotational spring constant K _BS
A model for calculating (K _BS = M / θ) will be described.

First, the amount of depression δ _C of the compression-side base plate will be examined and described.

(1) Assumption of compressive stress distribution on the upper surface of footing As shown in the left side diagram of FIG. 3A, the distribution of compressive stress on the upper surface of footing 12 is assumed to be trapezoidal to triangular, and a resultant compression force C acts. Let σ _C be the stress at the position.

Assuming the above, σ _C becomes as shown in equation (216).

The sigma _C = the ^{_{[4C (3x n 2 -3x n}} · D BS + D BS 2) / [3B BS · D BS (2x n -D BS) 2] ...... (216). Further, k _{2 xn} is the distance from the edge of the compression-side base plate 14 to the position where the compression resultant force C acts, and this k _{2 xn} is _expressed by the following equation (217).

K ₂ x _n = D _BS (3 × _n− 2D _BS ) / [3 (2 × _n− D _BS )] (217) where x _n is the bottom surface of the base plate 14 and the free surface X
Indicates the distance to the edge of the compression-side base plate from contact with, B _BS indicates the depth of the base plate.

(2) Replacement of Compressive Stress Distribution and Downward Diffusion of Compressive Stress In order to evaluate the subsidence amount δ _C of the base plate 14, the assumed stress distribution shape (see the left diagram in FIG. 3A) is made more uniform. The distribution is replaced with the distribution (the right view in FIG. 3A). At this time, the uniform stress value is changed to the stress σ _{C at} the position where the compression resultant C acts.
Take equal to. With this substitution, σ _C and k ₂ x _n
Are as shown in equations (218) and (219), respectively.

Σ _C = 4C / (3B _BS · x _n ) (218) k ₂ x _n = x _n / 3 (219) Based on the knowledge about bearing pressure, “this uniform compressive stress is It spreads uniformly vertically at a gradient of 1: 2. " The compressive strain ε _C on the surface of the footing 12 can be regarded as equation (220).

Ε _C = σ _C / E _C (220) (E _C : modulus of elasticity of concrete used for footing) By considering the equation (220), the internal vertical strain distribution is determined as a quadratic function of the vertical coordinate. As shown in A), the distortion is integrated in the vertical direction from the center of the footing 12 to the upper surface of the footing 12 (from 0 to Z ₁ ), so that the sinking amount δ of the base plate 14 at the position where the resultant compression force C acts. _C is obtained. Thus, [delta] _C (221)
It becomes an expression.

Δ _C = I ₁ (221) The right side I ₁ of the equation (221) is derived as in the following equation (222).

[0040]

(Equation 1)

Here, W is the width of the uniform compressive stress replaced as shown in FIGS. 3B and 4, and is expressed by the following equation (223). W = C / (B _BS · σ _C ) (223) Further, as shown in FIG. 5 (A), assuming that the diffusion range does not protrude from the footing side surface, H is expressed by the following equation (224). Defined in _{H = D F -D BS + 2k} 2 x n -W ...... (224) where, D _F is the eccentric distance from the base plate to the core of the footing.

As shown in FIG. 5 (B), assuming that the diffusion range does not protrude from the front surface and the rear surface of the footing, H ₁ and H ₂ are defined by the following equations (225) and (226). It is determined as follows.

H₁= B_F−B_BS−2e_y …… (225) H_Two= B_F−B_BS+ 2e_y (226) The core of the footing 12 and the core of the base plate 14 are shown in FIG.
Eccentricity e shown in (B) _yH₁<H_Two
And

It should be noted that the I ₂ shown in FIGS.
Accuracy is improved more by adding an element of ~I _6. Here, I ₂ corresponds to the case where the width of the footing is narrow and the diffusion range protrudes from the side surface (see FIG. 4B), and I ₂ is derived by the following equation (227).

[0045]

(Equation 2)

I ₃ corresponds to the case where the width of the footing is wide but the diffusion range protrudes from the front or rear surface (FIG. 4).
(See (C)), I ₃ is derived by the following equation (228).

[0047]

(Equation 3)

I ₄ corresponds to the case where the diffusion range protrudes from the side surface of the footing and protrudes from the front surface or the rear surface (see FIGS. 4D and 4E). I ₄ is derived from the following equation (229).

[0049]

(Equation 4)

[0050] I ₅ is diffusion range jumps out even rear surface also the front of the footing and corresponds to the case where not protrude from the side (FIG. 4 (F), (G)) refer). I ₅ is guided by the following (230) below.

[0051]

(Equation 5)

I ₆ corresponds to the case where the diffusion range protrudes all the front, rear and side surfaces of the footing (FIG. 4).
(H), (I)). I ₆ is derived from the following equation (231).

[0053]

(Equation 6)

Next, the top displacement δ of the tension-side anchor bolt
_T will be described. (1) Introduction of Equivalent Bearing Stress _q σ Acting on Fushi Shear stress is applied to the thread bottom 16A of the screw bolt 16A formed on the anchor bolt 16 in the footing 12, and compressive stress is further applied to the thread peak. (Fig. 6
(A)). This stress state is reduced by reducing the thickness without changing the height of the bulge, and the equivalent bearing stress _q σ is applied only to the flank of the bulge.
It is assumed that the displacement can be performed in the stress state in which
(See (B) and (C)). (2) Hypothetical distribution hypothesis of the equivalent bearing stress _q σ of the brush If the height of the footing 12 is sufficiently high and the embedding depth of the anchor bolt 16 is sufficiently deep, the equivalent bearing stress _q σ of the brush is obtained.
Decreases toward the bottom of the footing 12 and eventually becomes zero. As shown in FIG. 7, here, one of the simplest hypotheses that “the _q σ distribution is approximated as a discrete distribution enveloped in an inverted triangle and the distribution depth is constant regardless of the anchor bolt top stress” is I decided to introduce it.

The concept regarding the required adhesion length hc of anchor bolts (diameter d) in concrete having a strength σ _B is described in the Standards Association of New Zeala.
nd Concrete Design Standards, NZS31101, 1995); h _C
∽ (d / √σ _B ), Japan (standard for calculation of reinforced concrete structure); h _C ∽ (d ² / σ _B ), etc., and the idea of the above hypothesis is close to the latter.

FIG. 7A shows the strain distribution of the anchor bolt 16.
And the total strain distribution area including this is the top displacement δ _T of the tension-side anchor bolt.
Becomes Thus, [delta] _T is expressed by the following (232) below.

Δ _T = [H _m + T _BS + V _F + m · p _m / 3] _S ε _y (232) where H _m is the height of the anchor nut of the anchor bolt, and T _BS is the height of the base plate. thickness, V _F suffers a top concrete thickness, m is the p _m is the pitch section of the anchor bolt.

In order to evaluate the depth of the step distribution in FIG. 7 (A), _q σ at the time of tensile yielding at the top of the reinforcing _{bar is} defined as _q σ _sy and its maximum value is defined as
_It is referred to as _Qσsy (see FIG. 7B).

In this equation, [H _m + T _BS + V _F ] _S ε _y corresponds to the area of the upper square in the step distribution shown in FIG. 7A. When tightening the nut, anchor bolt 1
6 elongates, and if the amount of elongation is δ ₀ , [H _m + T _BS + V
_F] To further improve accuracy by the _S epsilon part of _{y [-δ 0 + H m +} T B S + V F] S ε y.

Further, the second half (m · p _m / 3) _S ε _{y of} this equation
Roh portion becomes a discrete distribution of rod-shaped distribution of the equivalent Bearing stress _q sigma _sy acting on the section anchor bolts 16 are encompassed inverted triangle height m '· p _m as shown in FIG. 8 (A). The length of the bar, each stage section is lowered one step, _Q σ _sy / m 'to decrease by the length _J sigma _sy of J-th rod from the _{top, J σ sy = Q σ sy} ( 1−J / m ′) …… (233) This is summed from J to k to _{m, and}
/ (A _t1 · E _S) those times becomes distorted _{m 'epsilon k} of k-th stage of the anchor bolt from above (see FIG. 8 (B)).

[0061] ^{_{m 'ε k = [k 2}} - (2m' + 1) k + (2m'-m) (m + 1)] (a m · Q σ sy / 2m '· a t1 · E S) ...... (234) Becomes The sum of k from 0 to _{m and} multiplied by PM is the area corresponding to the stepwise strain distribution in FIG. 8A, that is, the extension amount of the anchor bolt 16. Its value becomes _{S ε y (m · p m} / 3) · [(3m'-2m-1) / (2m'-m)] ...... (235). Since m 'is usually large enough, ｛(3m'-2
m−1) / (2m′−m)｝ may be regarded as 1, and _S ε _y (m
p _m / 3) is derived. The strain at the top of the anchor bolt _S ε _y
Is the yield strain, the above equation is the result of rearranging using the following relationship.

[0062] 'In _{(· a t1 · E S ......} (236) This equation, _{usually, m S ε y = (2m'} -m) (m + 1) a m · Q σ sy / 2m)' value of sufficiently Because it is large, m
= M ', and the following equation can be derived.

M = 2a _t1 · _S σ _y / (a _m · _Q σ _sy ) −1 (237) The amount of elongation at the time of tightening the nut is the first term I ₀
And the second half. The latter term is δ _T = when strain _S ε ₀ during nut tightening is applied to the top of the anchor bolt.
Elongation of _{[H m + T BS + V} F + m · p m / 3] anchor bolt 16 corresponding to the _S epsilon _y, is the _S epsilon _y of the equation just replaced with _S epsilon _{0. Accordingly, δ 0 = I 0 + [} H m + T BS + V F + m · p m / 3] S ε 0 ...... (238) I 0 = (a t + a C) E S · S ε 0 / (B _BS -D _BS ) × log [(H _F / 2 + D _BS ) B _BS / [(H _F / 2 + B _BS ) D _BS ]] …… When B _BS −D _BS ≠ 0 = (a _{t + a C) E S ·} S ε 0 · H F / [(H F + 2B BS) D BS] when ...... (239 ...... B _BS -D _BS = 0) the first half of the term sinking of the base plate is the amount, this was applied mutatis mutandis the I _1. That is, as shown in FIG. 9, when the footing 12 is sufficiently large, it is determined that the footing 12 can be evaluated on the safe side,
When tightening the nut, the lower surface of the base plate 14
Is a sinking amount when a uniform compressive stress corresponding to the tightening force is applied. Thus, in the formula I _0, the formula I ₁ C, W,
The z ₁ respectively _{{(a t + a C)} E S · S ε 0}, D BS, H F / 2
Was replaced by However, when the shape of the base plate 14 is a square, the shape of the result of the equation slightly changes. (3) Hypothesis for Evaluating Influence of Anchor Bolt Interval _{Q sy} when the anchor bolt 16 interval is sufficiently large is referred to as a basic equivalent bearing strength _{Q 1} σ _sy of a fusi (see FIG. 10A). It is assumed that the property that the apparent adhesion strength decreases when the distance between the anchor bolts 16 is reduced is explained by the following hypothesis.

The tensile yield strength of one anchor bolt is shown in FIG.
10A is mainly transmitted by τ on the side of the cylindrical influence range such as 0 (A). When the interval between the anchor bolts 16 is reduced, the i influence ranges overlap as shown in FIG. 10B. The outer circumference length value of the horizontal cross section is increased, but the outer circumference length _i per anchor bolt and the side area are reduced,
Since there is a limit to the value of τ on the side, this is the cylinder height (∽
_q σ _sy ).

The depth becomes larger as the diameter / yield strength _s σ _y of the anchor bolt 16 is larger, and as the space between the anchor bolts 16 and the concrete strength of the footing 12 are smaller, the _Q σ _sy value is reduced. The _Q To evaluate the sigma _sy value as shown in FIG. 10 (A) hatched portion, and introducing the outer peripheral length [psi _l horizontal cross section of the toroidal cylinder containing these factors stipulated, "Figure 10 (B) When the influence ranges of the i reinforcing bars overlap, the _Q σ _sy value becomes (ψ _i / ψ _l ) × _{Q 1} σ _sy ”
Introduced one of the simplest hypotheses.

Therefore, as shown in FIG. 10 (B), it is assumed that the equivalent bearing strength _Q σ _sy of the bush when the anchor bolt interval is narrow and the range of influence overlaps i pieces is evaluated by the following equation. it can. Incidentally radius give circumference [psi ₁ in FIG. 10 is a Arupusai. _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (240) ψ _i = 2 [π · Rψ (i−1) s] / i …… (241) ψ ₁ = 2π · Rψ …… ( 242) Rψ = [a _t1 (1 + _S σ _y / F _C ) / π] ^1/2 (243) Next, an example of the convergence calculation procedure will be described. In addition,
At present, for example, general-purpose spreadsheet software such as Microsoft Excel is widely and widely used, and its standard function can perform convergence calculation at the same level as the four arithmetic operations. An example is shown.

Fushi basic equivalent bearing strength_Q1σ_syThe value of
When evaluated from the results of the experiment, as shown in FIG.
And the equivalent bearing stress of the fusi_qσ_syTriangle distribution depth of
To determine the strain at the top of the tension anchor bolt (≤
Yield strain) and top displacement δ_TAnd the value of tensile force T
Can be determined. Once the value of T is determined, is the force in the vertical direction balanced?
The value of the resultant compression force C acting on the lower surface of the base plate is determined from
You. Next, in FIG. 3B, the position where the resultant compression force C acts.
Provisional value of footing 12 concrete compression strain ε _C ^*give
Then, the corresponding provisional stress σ_C ^*, Provisional neutral axis position x
_n ^*, Provisional C position k_Twox_n ^*Are sequentially obtained. These and Fu
Free surface X of the chin 12 and the rigid base plate 1
From the geometrical relationship with No. 4, the compression resultant C shown in FIG.
One of the provisional displacements of the position_C ^*Occurs.

On the other hand, another provisional displacement δ _C ^** also occurs from the area of the vertical compressive strain distribution of the concrete in the footing 12 shown by the hatched portion in FIG. The two provisional displacement values do not match unless the value of ε _C ^* is true. In order to make this converge, if the (δ _C ^* −δ _C ^** ) term is an input term, 0 is a target value term, and a term that changes ε _C ^* , the convergence solution ε _C and the target value δ _C = Since δ _C ^* = δ _C ^** is obtained, finally, the bending moment M and the rotation angle θ of the base plate 14 shown in FIG. 1 are calculated, and the rotation spring constant is calculated.

Further, the hypothesis used in the above-described study model was verified by experiments. In verifying the hypotheses used in the above study model, all the experimental values except for when the loading bending moment was unloaded until the tops of the anchor bolts of the three test specimens to be subjected to tensile yielding were extracted.

In the experiment, six anchor bolts 1 were attached to both edges of the base plate 14 as shown in FIG.
6, a test piece having four anchor bolts 16 disposed on both edges of the base plate 14 as shown in FIG. 11B, and a test piece having both edges of the base plate 14 as shown in FIG. A test body in which two anchor bolts 16 were arranged was used.

Also, in the study model, the fixing plate at the lower end of the anchor bolt provided on the test body was ignored, and the portion below the footing core was replaced with a shape that is infinitely continuous.
Then, the value of the fushi basic equivalent bearing strength _Q1 σ _sy is calculated as σ _B ×
Set in increments of 0.5, and for each, set the strain _S ε _T at the top of the tension side anchor bolt at 100 × 10 ^-6 intervals from the nut tightening strain _S ε ₀ to the yield strain, and calculate the convergence. went. Here, three levels ( _Q1 σ _sy = 2.0, 2..
5, and 3.0 × σ _B ).

(1) Strain distribution properties of tension anchor bolts As shown in FIGS. 12A, 12B and 12C, the calculated value of the strain of the tension anchor bolt 16 decreases as the embedding depth increases. However, the results of the three levels show a spread of about ± 10% with respect to the top strain. This tendency does not depend on the column axial force, the diameter of the anchor bolt, the number of anchor bolts, the distance between the anchor bolts, and the nut tightening force on the anchor _bolt.The value of the basic equivalent bearing strength _Q1 It can be seen that the axial strain distribution of the bolt is not significantly affected. The experimental values are obtained by measuring the strains of all the anchor bolts 16 on the tension side.
It is the average value of the points, but the range of the variation reaches nearly 30% of the top distortion. The engineering, _Q1 σ value of _sy is 2~3σ
If it is in the range of _B , it can be understood that the above-mentioned hypothesis is a hypothesis for unifyingly explaining the measured strain value shown by the experiment. (2) Regarding the sinking displacement of the base plate As shown in FIGS. 13A, 13B and 13C, the calculated displacement difference between the rising and sinking of the base plate 14 shows a slightly slip type result. Among the three levels, a variation of about ± 10% is given to the median value of the displacement difference. When the column axial force is increased, the contribution of the sinking amount of the base plate 14 is increased, so that the width of the variation is somewhat narrowed. Value of the basic equivalent bearing capacity _Q1 sigma _sy of knots anyway it can be seen that does not have a significant effect on the rotation angle of the base plate.

The experimental value is the difference between the measured values at the end of the base plate (5 points) between the compression side anchor bolts and the corresponding linear interpolation values of the top side displacement of the tension side anchor bolts. Although the measured value has a large degree of harassment, it corresponds well with the calculated value. _Q1 sigma hypothesis value of _sy is the if the range of 2～3Shiguma _B is found to be hypotheses explaining also unified manner the amount measured value sinking of the base plate 14 indicated by the experiment. (3) About the action position of the compression resultant force C As shown in FIGS. 14 (A), (B) and (C), the action position k _{2 xn of} the compression resultant force C acting on the lower surface of the base plate 14.
The calculated value is a typical slip type. By the way, the results of three levels of concrete compressive strain ε _C of the footing 12 at the C position show the same properties as the previous section, while the values of three levels of k ₂ × _n are almost the same. for basic equivalent bearing capacity _Q1 sigma range _sy of, variation of _Q1 sigma _sy can be seen as affecting C operating position, there is no problem in the evaluation of M.

The experimental values were the column axial force, the diameter of the anchor bolt,
The calculated values correspond well to the calculated values irrespective of the number of anchor bolts, the spacing between the anchor bolts, and the nut tightening force on the anchor bolts, and almost coincide with the calculated values particularly at the time of anchor bolt end tension yielding. (4) Regarding the bending moment M The calculated value of the bending moment M acting on the lower surface of the base plate 14 is affected by the fluctuation of the basic equivalent bearing strength _Q1 σ _sy of the fir in the range of these three levels as in the previous section. No (see FIG. 15). In addition, although it is almost proportional to the strain value at the top of the tension-side anchor bolt, if the amount of rebar is small, the properties of the slip type can be seen. The experimental value measurement results also show the properties according to the calculation results. (5) Rotational Spring Rigidity of Base Plate 14 As shown in FIG. 16A, when the column axial force is low, the calculated value of the rotational spring stiffness of the base plate 14 is 3 which is the basic equivalent bearing strength _Q1 σ _sy of the _brush . It is affected by about ± 10% of the level fluctuation range. However, as shown in FIGS. 16 (B) and (C), there is almost no effect when the axial force increases, and the rotational rigidity gradually decreases as M increases. The experimental measured values also show the properties according to the calculated values.

Although the rotation angle θ is the same as the horizontal axis in FIG. 13 and the width of the variation is large, it is considered appropriate to evaluate the design spring constant based on the secant rigidity at the time of the anchor bolt's top tensile yielding. In order to determine the design rotation spring constant value on the safe side (lower value), the value of the basic equivalent bearing strength _Q1 σ _sy of the brush in the above-described model is 2σ _B (+ mark plot in the figure)
And it is sufficient. If the anchor bolt strain distribution corresponding to _Q1 σ _sy is 336 × 10 ^-6 or less at the bottom of the footing 12, it does not affect the design rotational spring constant value (FIG. 12).
(A)). Other applicable ranges are _S ε ₀ ≦ 383 × 10 ⁻⁶ ,
_S σ _y ≦ 363 N / mm ² , d ≦ 22 mm, 2.82d ≦
Rebar spacing, σ _B ≦ 34.5 N / mm ² , (approximate compression axial force / base plate bottom area) ≦ 0.263σ _B.

As described above, the thick steel base plate 14 for the concrete column base and the concrete footing 1
A simple model for the exposed column base fixed to 2 was examined, and the base plate 14 and the footing 1 were assumed to be rigid.
The value of the relative rotation spring constant between the two was calculated. According to this, the amount by which the compression-side base plate 14 sinks into the footing 12 and the amount of elongation of the tension-side anchor bolt 16 can be calculated by providing the following simple hypotheses.

The compressive force applied to the upper surface of the footing from the base plate diffuses into the lower concrete at a gradient of 1: 2.

The adhesion stress of the tension side anchor bolt can be replaced with the equivalent bearing stress _q σ of the brush.

The _q σ distribution can be approximated as an inverted triangle distribution having a constant depth.

The maximum value of _q σ when the anchor bolt apex yields is _Q σ _sy , and when the interval between the reinforcing bars is sufficiently large, _Q σ _sy
Is the basic equivalent bearing strength _Q1 σ _sy of the fusi and the rebar spacing is _Q σ
_The influence on _sy can be evaluated based on the overlapping shape of the range in which adjacent reinforcing bars affect.

The evaluation model constructed on the basis of the above hypotheses has the following characteristics. (1) Basic equivalent bearing capacity _Q1 sigma _sy section does not significantly affect the axial strain distribution of the tension side anchor bolt. (2) The fluctuation of the _Q1 σ _sy value hardly affects the position where the compressive resultant force acts on the lower surface of the base plate. (3) Even if the _{Q1 σsy} value is changed, the rotational rigidity of the base plate does not change significantly.

Further, based on the measurement results of an experiment in which the column axial force, the diameter of the anchor bolt, the number of anchor bolts, the distance between the anchor bolts, and the nut tightening force with respect to the anchor bolt were used as variables, the base plate until the start of the anchor bolt top tensile yielding was obtained. The following findings were obtained with regard to the neutrality of the rotating hill. (4) The strain measurement results of the tension-side anchor bolt corresponded favorably to the calculation results using the hypothesis. Regarding the basic equivalent bearing strength _Q1 σ _sy of the brush used in the hypothesis, even if the column axial force, anchor bolt diameter, number, spacing, and nut tightening force fluctuate, one _Q1 σ _sy value changes the tension side anchor. The bolt strain measurement results were explained in common. (5) The subsidence amount experimental value of the compression side base plate corresponded favorably to the calculated value using the hypothesis. (6) The experimental value of the compressive resultant force acting position on the lower surface of the base plate corresponded well to the calculated value, and almost coincided with the calculated value especially at the time of tensile yielding at the top of the anchor bolt. (7) The experimental values of the bending moment acting on the lower surface of the base plate corresponded well with the calculated values. (8) The rotational rigidity experimental values of the base plate corresponded favorably to the values calculated by the study model.

[0083] With respect to the spring constant value to be set in rotation spring exposed fixation column base in practical design, in the above model and _{Q1 σ sy} = 2F _C, giving a tensile yield strain in the anchor bolt top, at that time The calculated secant rigidity can be used as the design spring constant value.

The evaluation of the above-mentioned exposed fixed column base can be performed by using, for example, a general-purpose computer 30 as shown in FIG. At this time, the predetermined program and the above-described design formula of the rotation spring constant are installed in the computer 30 from a recording medium such as the CD-ROM 32 in which the predetermined program is stored in advance,
According to the installed program, necessary parameters are input to calculate the rotation spring constant.

As described above, by evaluating the rotation-type spring constant using the above equation and evaluating the exposed fixed column base, it is possible to use a reinforcing bar having a threaded thread such as a general anchor bolt. Costs can be reduced,
In addition, the extension of the anchor bolt can be suppressed, and the rotational rigidity can be improved. In addition, since the sinking deformation of the compression side concrete of the base plate is strictly evaluated, and the initial tightening of the anchor bolts is also properly evaluated,
A more accurate rotation spring constant value can be obtained. Therefore, in the exposed fixed column base, the optimum rotation spring constant can be calculated even when the screw bar made of ordinary steel is used as the anchor bolt, and the cost can be reduced.

[0086]

As described above, according to the present invention, since the design formula can be used for a rebar with adhesion such as a general anchor bolt, the cost can be reduced,
In addition, the extension of the anchor bolt can be suppressed, and the rotational rigidity can be improved. In addition, since the sinking deformation of the concrete on the compression side of the base plate is strictly evaluated, the initial tightening of the anchor bolts is also properly evaluated,
An excellent effect that a more accurate rotation spring constant value can be obtained is exhibited.

[Brief description of the drawings]

FIG. 1A is a view showing a state in which an anchor bolt is fixed to a footing and before a nut is fastened to the anchor bolt in the exposed-type fixed column base according to the embodiment of the present invention; FIG. FIG. 1B is an explanatory view showing a state where the anchor bolt is fixed to the footing, and showing a state after the nut is fastened to the anchor bolt.

FIG. 2 is an explanatory view showing a state in which a column base bending moment M and a column axial compression force N act on a base plate in the exposed fixed column base according to the embodiment.

FIG. 3 is an explanatory view showing a concept of a sinking amount δ _C of a compression-side base plate in the exposed fixed column base according to the embodiment, and FIG. 3 (A) is an explanation of an assumption of a surface stress. FIG. 3B is an explanatory diagram of the distribution type replacement, the downward diffusion, and the vertical distribution of stress / strain.

FIG. 4 is an explanatory diagram of a case where the exposed fixed column base according to the embodiment is replaced with a uniform distribution and a footing is sufficiently large.

FIG. 5 (A) shows the uniform compressive stress width W in which the distribution type is replaced in the exposed fixed column base according to the embodiment.
FIG. 5B is an explanatory view of a range H in which the range of downward diffusion does not protrude from the side surface of the footing.

FIG. 6 is an equivalent bearing stress _q acting on a bolt of an anchor bolt in the exposed fixed column base according to the embodiment;
FIG. 9 is an explanatory diagram of σ.

FIG. 7 is an equivalent bearing stress _q acting on the anchor bolt in the exposed fixed column base according to the embodiment.
FIG. 7 is an explanatory diagram of the vertical distribution hypothesis of σ, and FIG.
(A) is an explanatory view at the time of stress acting on a general anchor bolt, and FIG. 7 (B) is an explanatory view at the time of a top yielding of the anchor bolt.

8 (A) is an explanatory view of the distribution of the equivalent bearing stress _q σ _sy of the anchor bolt's brush in the exposed fixed column base according to the embodiment, and FIG. 8 (B) is FIG. FIG. 4 is an explanatory diagram of a strain distribution _s ε _y of an anchor bolt.

FIG. 9 is a view showing a case where footing is sufficiently large in the exposed fixed column base according to the embodiment and a case where a lower surface of the base plate receives a uniform stress corresponding to a nut tightening force when the nut is tightened. FIG.

FIG. 10 is an explanatory diagram in the case of evaluating the effect of the spacing of anchor bolts on the equivalent bearing strength σ _sy of the anchor bolt in the exposed fixed column base according to the embodiment; 10) is an explanatory diagram when the interval between the anchor bolts is sufficiently large, and FIG. 10B is an explanatory diagram when the interval between the anchor bolts is narrow and the range of influence is overlapped by i.

FIG. 11 is an explanatory view of a test body used in an experiment for verifying a hypothesis in the embodiment, and FIG. 11A shows a test in which six anchor bolts 16 are arranged on both edges of a base plate. FIG. 11B is an explanatory view of a test body in which four anchor bolts 16 are arranged on both edges of the base plate, and FIG. 11C is a diagram illustrating two test pieces on both edges of the base plate. It is explanatory drawing about the test body which arrange | positioned the anchor bolt 16 of FIG.

FIG. 12 is an explanatory diagram showing a distortion property of an anchor bolt embedded in a footing in the exposed fixed column base according to the embodiment.

FIG. 13 is an explanatory diagram showing a floating displacement and a sinking displacement of a base plate in the exposed fixed column base according to the embodiment.

FIG. 14 is an explanatory diagram showing an acting position and distortion of a compressive resultant force acting on a lower surface of a base plate in the exposed fixed column base according to the embodiment.

FIG. 15 is an explanatory diagram showing a bending moment acting on the lower surface of the base plate in the exposed fixed column base according to the embodiment.

FIG. 16 is an explanatory view showing the rotation spring rigidity of the base plate in the exposed fixed column base according to the embodiment.

FIG. 17 is a schematic explanatory view showing an example of an apparatus for evaluating the exposed fixed column base according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Exposure fixed column base 12 Footing 14 Base plate 16 Anchor bolt 16A Screw thread 18 Column 20 Nut

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuo Okamoto 4-1-1-13, Honcho, Chuo-ku, Osaka-shi, Osaka Inside the Osaka Main Store of Takenaka Corporation (72) Inventor Katsumichi Tabuchi Honcho, Chuo-ku, Osaka-shi, Osaka 4-1-1-13 Takenaka Corporation Osaka Main Store (72) Inventor Hideo Nojima 4-1-1-13 Honcho Chuo-ku Osaka-shi Osaka Prefecture F-term In Osaka Main Store Takenaka Corporation 2D046 AA17 2E125 AA04 AA45 AB13 AC14 AG20 AG41 BA02 BB08 BC08 BD01 BE08 BF04 BF08 CA04 2E163 DA00 FA02 FB01 FB21

Claims (4)

[Claims] 1. An exposed fixed column base for fixing a base plate, to which a steel column of a building is joined, to a footing concrete foundation with an anchor bolt having a threaded body, by using a bending moment M of the column base and a rotation angle θ of the base plate. In the method for evaluating an exposed fixed column base evaluated by using the rotation spring constant K _BS of the column base expressed by the following formula (1) expressed by the ratio: K _BS = M / θ (1) Bending moment of the column base _Let M and the rotation angle θ of the base plate be M = C (D _BS / 2−k _{2 xn} ) + T (D _BS / 2−d _t ) (2) θ = (δ _T + δ _C ) / (D _BS −k _{2 xn} −d _t ) (3) An evaluation method for an exposed fixed column base characterized by being evaluated as (3). Here, k ₂ x _n = x _n / 3 (4) x _n = 4C / (3B _BS · σ _C ) (5) C = N + T (6) T = a _t · E _S · _S ε _y …… (7) δ _C = I ₁ …… (8) I ₁ = C / [E _C · (B _BS −W)] × log [(z ₁ + W) B _BS / [(z ₁ + B _BS ) W]] …… (9) W = C / (B _BS / σ _C ) …… (10) H = D _F −D _BS + 2k ₂ x _n −W …… (11) H ₁ = B _F −B _BS −2e _y …… (12) H ₂ = B _F −B _BS + 2e _y …… (13) σ _C = E _C · ε _C …… (14) δ _T = [H _m + T _BS + V _F + m · p _m / 3] _S ε _y …… (15) I ₀ = [(a _t + a _C ) E _S · _S ε ₀ / (B _BS −D _BS )] × log [(H _F / 2 + D _BS ) B _BS / [(H _F / 2 + B _BS ) D _BS ]] …… When B _BS −D _BS ≠ 0 = ( a _t + a _C ) E _S・_S ε ₀・ H _F / [(H _F + 2B _BS ) D _BS ] …… When B _BS −D _BS = 0 …… (16) m = 2a _t1 · _S σ _y / (a _m / _Q σ _sy ) −1 …… (17) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (18) ψ _i = 2 [π · Rψ + (i−1) s] / i …… (19) ψ ₁ = 2π · Rψ …… (20) Rψ = [a _t1 (1 + _S σ _y / F _C ) / π] ^1/2 …… (21) _Q1 σ _sy = 2F _C …… (22) δ _C ^* = (x _n ^* -k ₂ x _n ^* ) δ _T / (D _BS / 2-d _t ) …… (23) N: Design column compression axial force F _C : Footing concrete design standard strength E _C: modulus of elasticity of the footing concrete H _F: footing height V _F: fog thickness of the upper surface concrete footing B _F: footing back of Can Direction (M-axis direction) dimension B _BS: depth of the base plate T _BS: The thickness of the base plate D _BS: because of the base plate d _t: distance from the edge of the base plate to the tension side anchor bolts core D _F / 2: distance from the base plate core as measured in D _BS direction about the compression side footing to the edge e _y: B eccentricity distance from the base plate core as measured in the _BS direction to the core of the footing a _t1: tension side anchor bolt one of the cross-sectional area _S σ _y : Yield strength of the cross-sectional area of one tension anchor bolt E _S : Elastic modulus _S of the tension anchor bolt _S ε _y : Yield strain of the tension anchor bolt a _m : Projected bearing area of the screw bolt of the anchor bolt in the axial direction p _m : Pitch of screw thread of anchor bolt H _m : Height of anchor nut s: Center distance of anchor bolt a _t : Total cross-sectional area of tension side anchor bolt a _C : Compression side anchor bolt Total sectional area _S ε ₀ : Nut tightening distortion i: Total number of tension anchor bolts in a group that satisfies condition [s ≦ 2Rψ] (If not satisfied, i = 1) 2. An exposed fixed column base for fixing a base plate, to which a steel column of a building is joined, to a footing concrete foundation by means of anchor bolts having threaded bolts, by using a bending moment M of the column base and a rotation angle θ of the base plate. The rotation spring constant K _BS of the column base of the following formula (24) expressed by the ratio
In the method of evaluating an exposed fixed column base using the following equation, K _BS = M / θ (24) The bending moment M of the column base and the rotation angle θ of the base plate are calculated as follows: M = C (D _BS / 2− k ₂ x _n ) + T (D _BS / 2−d _t ) (25) θ = (δ _T + δ _C ) / (D _BS −k ₂ x _n −d _t ) ... (26) An evaluation method of an exposed fixed column base characterized by the following. Where k ₂ x _n = x _n / 3 (27) x _n = 4C / (3B _BS · σ _C ) ··· (28) C = N + T ··· (29) T = a _t · E _S · _S ε _y ... (30) δ _C = I ₁ + I ₂ + I ₃ + I ₄ + I ₅ + I ₆ ... (31) I ₁ = C / [E _C · (B _BS -W)] × log [(z ₁ + W) B _BS / [(z ₁ + B _BS ) W]] …… (32) I ₂ = 2C / [E _C · (B _BS −2W)] × log [(z ₃ + 2W) (z ₂ + B _BS ) / [(z ₃ + B _BS ) (z ₂ + 2W)]]… (3 3) I ₃ = 2C / [E _C · (W−2B _BS )] × log [(z ₃ + 2B _BS ) (z ₂ + W ) / [(z ₃ + W) (z ₂ + 2B _BS )]] ... (3 4) I ₄ = C / [E _C · (B _BS −W)] × log [(z ₅ + 2W) (z ₄ + 2B _BS ) / [(z ₅ + 2B _BS ) (z ₄ + 2W)]] ... (3 5) I ₅ = C / (E _C · B _F ) × log [(z ₅ + W) / (z ₄ + W)] …… (36) I ₆ = 2C / (E _C · B _F ) × log [(H _F / 2 + 2W) / (z ₆ + 2W)] …… (37) W = C / (B _BS / σ _C )… … (38) [Table 2] H = D _F −D _BS + 2k ₂ x _n −W …… (39) H ₁ = B _F −B _BS −2e _y …… (40) H ₂ = B _F −B _BS + 2e _y …… (41) σ _C = E _C · ε _C …… (42) δ _T = [− δ ₀ + H _m + T _BS + V _F + m · p _m / 3] _S ε _y …… (43) δ ₀ = I ₀ + [H _m + T _{BS + V F + m · p} m / 3] S ε 0 ...... (44) I 0 = [(a t + a C) E S · S ε 0 / (B BS -D BS)] × log [(H _F / 2 + D _BS ) B _BS / [(H _F / 2 + B _BS ) D _BS ]] …… When B _BS −D _BS ≠ 0 = (a _t + a _C ) E _S · _S ε ₀ · H _F / [(H _F + 2B _BS ) D _BS ] …… B _BS −D _BS = 0 …… (45) m = 2a _t1 · _S σ _y / (a _m / _Q σ _sy ) −1 …… (46) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (47) ψ _i = 2 [π · Rψ + (i−1) s] / i …… (48) ψ ₁ = 2π · Rψ …… (49) Rψ = [a _t1 (1+ _S σ _y / F _C ) / π] ^1/2 …… (50) _Q1 σ _sy = 2F _C …… (51) δ _C ^* = (x _n ^* -k ₂ x _n ^* ) δ _T / (D _BS / 2-d _t ) …… (52) N: Compressive axial force of design column F _C : Design standard strength of footing concrete E _C : Elastic coefficient of footing concrete H _F : Height of footing V _F : Foot Overburden thickness of top concrete grayed B _F: footing in the depth direction (M direction) dimension B _BS: depth of the base plate T _BS: The thickness of the base plate D _BS: because of the base plate d _t: side pulling from the edge of the base plate the distance until the anchor bolt core D _F / 2: distance from the base plate core as measured in D _BS direction about the compression side footing to the edge e _y: eccentric distance from the base plate core as measured in the B _BS direction to the core of the footing a _t1 : Cross section area of one tension side anchor bolt _S σ _y : Yield strength of one cross section of tension side anchor bolt E _S : Elastic coefficient _{S of} tension side anchor bolt _S ε _y : Yield strain of tension side anchor bolt a _m: axial projection of Nejifushi anchor bolts Bearing area p _m: pitch H _m of Nejifushi anchor bolts: fixing nut height s: center of the anchor bolt spacing a _t: tensile side Total cross-sectional area of anchor bolt a _C : Total cross-sectional area of compression-side anchor bolt _S ε ₀ : Nut tightening strain i: Total number of a group of tension-side anchor bolts satisfying condition [s ≦ 2Rψ] i = 1) 3. An exposed fixed column base for fixing a base plate, to which a steel column of a building is joined, to a footing concrete foundation with an anchor bolt having a threaded body, by using a bending moment M of the column base and a rotation angle θ of the base plate. The rotation spring constant K _BS of the column base of the following formula (53) expressed by the ratio
K _BS = M / θ (53) The bending moment M of the column pedestal and the rotation angle θ of the base plate are calculated as follows: M = C (D _BS / 2− k ₂ x _n ) + T (D _BS / 2−d _t ) ... (54) Evaluate as θ = (δ _T + δ _C ) / (D _BS −k ₂ x _n −d _t )… (55) An evaluation device for an exposed fixed column base. _{Here, k 2 x n = x n} / 3 ...... (56) x n = 4C / (3B BS · σ C) ...... (57) C = N + T ...... (58) T = a t · E S · _S ε _y …… (59) δ _C = I ₁ …… (60) I ₁ = C / [E _C · (B _BS −W)] × log [(z ₁ + W) B _BS / [(z ₁ + B _BS ) W]] …… (61) W = C / (B _BS / σ _C ) …… (62) H = D _F −D _BS + 2k ₂ x _n −W …… (63) H ₁ = B _F −B _BS −2e _y …… (64) H ₂ = _BF −B _BS + 2e _y …… (65) σ _{C = E C · ε C ......} (66) δ T = [H m + T BS + V F + m · p m / 3] S ε y ...... (67) I 0 = [(a t + a C) E S · _S ε ₀ / (B _BS −D _BS )] × log [(H _F / 2 + D _BS ) B _BS / [(H _F / 2 + B _BS ) D _BS ]] …… When B _BS −D _BS ≠ 0 = ( a _t + a _C ) E _S・_S ε ₀・ H _F / [(H _F + 2B _BS ) D _BS ] …… When B _BS −D _BS = 0 …… (68) m = 2a _t1 · _S σ _y / (a _m / _Q σ _sy ) −1 …… (69) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (70) ψ _i = 2 [π · Rψ + (i−1) s] / _{i ...... (71) ψ 1 =} 2π · Rψ ...... (72) Rψ = [a t1 (1+ S σ y / F C) / π] 1/2 ...... (73) Q1 σ sy = 2F C ...... (74) δ _C ^* = (x _n ^* -k ₂ x _n ^* ) δ _T / (D _BS / 2-d _t ) …… (75) N: Design column compression axial force F _C : Footing concrete design standard strength E _C: modulus of elasticity of the footing concrete H _F: footing height V _F: fog thickness of the upper surface concrete footing B _F: footing back of Can Direction (M-axis direction) dimension B _BS: depth of the base plate T _BS: The thickness of the base plate D _BS: because of the base plate d _t: distance from the edge of the base plate to the tension side anchor bolts core D _F / 2: distance from the base plate core as measured in D _BS direction about the compression side footing to the edge e _y: B eccentricity distance from the base plate core as measured in the _BS direction to the core of the footing a _t1: tension side anchor bolt one of the cross-sectional area _S sigma _y: yield strength of the cross-sectional area of the tension-side anchor bolt one E _S: elastic modulus of the tension side anchor bolt _S epsilon _y: yield strain of the tension side anchor bolt a _m: axially projected Bearing area of Nejifushi of the anchor bolt p _m : Pitch of screw thread of anchor bolt H _m : Height of anchor nut s: Center distance of anchor bolt a _t : Total cross-sectional area of tension side anchor bolt a _C : Compression side anchor bolt Total cross-sectional area _S ε ₀ : Nut tightening strain i: Total number of tension anchor bolts in a group that satisfies condition [s ≦ 2Rψ] (If not satisfied, i = 1) 4. An exposed fixed column base for fixing a base plate, to which a steel column of a building is joined, to a footing concrete foundation with an anchor bolt having a threaded body, by using a bending moment M of the column base and a rotation angle θ of the base plate. The rotation spring constant K _BS of the column base of the following formula (79) expressed by the ratio
K _BS = M / θ (76) The bending moment M of the column pedestal and the rotation angle θ of the base plate are calculated as follows: M = C (D _BS / 2− k ₂ x _n ) + T (D _BS / 2−d _t ) …… (77) Evaluate as θ = (δ _T + δ _C ) / (D _BS −k ₂ x _n −d _t ) …… (78) An evaluation device for an exposed fixed column base. Here, k ₂ x _n = x _n / 3 (79) x _n = 4C / (3B _BS · σ _C ) ··· (80) C = N + T ··· (81) T = a _t · E _S · _S ε _y …… (82) δ _C = I ₁ + I ₂ + I ₃ + I ₄ + I ₅ + I ₆ …… (83) I ₁ = C / [E _C · (B _BS −W)] × log [(z ₁ + W) B _BS / [(z ₁ + B _BS ) W]] …… (84) I ₂ = 2C / [E _C · (B _BS −2W)] × log [(z ₃ + 2W) (z ₂ + B _BS ) / [(z ₃ + B _BS ) (z ₂ + 2W)]] …… (85) I ₃ = 2C / [E _C · (W−2B _BS )] × log [(z ₃ + 2B _BS ) (z ₂ + W ) / [(z ₃ + W) (z ₂ + 2B _BS )]] ... (8 6) I ₄ = C / [E _C · (B _BS −W)] × log [(z ₅ + 2W) (z ₄ + 2B _BS ) / [(z ₅ + 2B _BS ) (z ₄ + 2W)]]… (8 7) I ₅ = C / (E _C · B _F ) × log [(z ₅ + W) / (z ₄ + W)] …… (88) I ₆ = 2C / (E _C · B _F ) × log [(H _F / 2 + 2W) / (z ₆ + 2W)] …… (89) W = C / (B _BS / σ _C )… … (90) [Table 4] H = D _F −D _BS + 2k ₂ x _n −W …… (91) H ₁ = B _F −B _BS −2e _y …… (92) H ₂ = B _F −B _BS + 2e _y …… (93) σ _{C = E C · ε C ......} (94) δ T = [- δ 0 + H m + T BS + V F + m · p m / 3] S ε y ...... (95) δ 0 = I 0 + [H m + T _{BS + V F + m · p} m / 3] S ε 0 ...... (96) I 0 = [(a t + a C) E S · S ε 0 / (B BS -D BS)] × log [(H _F / 2 + D _BS ) B _BS / [(H _F / 2 + B _BS ) D _BS ]] …… When B _BS −D _BS ≠ 0 = (a _t + a _C ) E _S · _S ε ₀ · H _F / [(H _F + 2B _BS ) D _BS ] …… B _BS −D _BS = 0 …… (97) m = 2a _t1 · _S σ _y / (a _m / _Q σ _sy ) −1 …… (98) _Q σ _sy = (ψ _i / ψ ₁ ) _Q1 σ _sy …… (99) ψ _i = 2 [π · Rψ + (i−1) s] / i …… (100) ψ ₁ = 2π · Rψ …… (101) Rψ = [a _t1 (1+ _S σ _y / F _C ) / π] ^1/2 …… (102) _Q1 σ _sy = 2F _C …… (103) δ _C ^* = (x _n ^* -k ₂ x _n ^* ) δ _T / ( _DBS / 2- _dt ) …… (104) N: Compressive axial force of design column F _C : Design standard strength of footing concrete E _C : Elastic coefficient of footing concrete H _F : Height of footing V _F : Who Top cover concrete thickness of chin B _F : Depth direction of footing (M axis direction) B _BS : Depth dimension of base plate T _BS : Thickness of base plate D _BS : Base plate d _t : Pull side from edge of base plate the distance until the anchor bolt core D _F / 2: distance from the base plate core as measured in D _BS direction about the compression side footing to the edge e _y: eccentric distance from the base plate core as measured in the B _BS direction to the core of the footing a _t1 : Cross section area of one tension side anchor bolt _S σ _y : Yield strength of one cross section of tension side anchor bolt E _S : Elastic coefficient _{S of} tension side anchor bolt _S ε _y : Yield strain of tension side anchor bolt a _m: axial projection of Nejifushi anchor bolts Bearing area p _m: pitch H _m of Nejifushi anchor bolts: fixing nut height s: center of the anchor bolt spacing a _t: argument The total cross-sectional area of the side anchor bolt a _C: the total cross-sectional area _S epsilon ₀ of the compression side anchor bolts: nut tightening when distortion i: condition when [s ≦ 2Rψ] total number (not met a group of tension-side anchor bolt satisfying Is i = 1)