JP5752846B1 - Column base structure - Google Patents

Abstract

When a load that generates a bending moment due to an earthquake or the like is applied, it is possible to prevent the joint between the joint metal and the column member from locally yielding and breaking the joint, and to join the metal joint and the column. A column base structure capable of preventing an increase in manufacturing cost of a leg structure is provided. A column 42 in which a metal joint 42 arranged above the foundation concrete 3 is fixed to the anchor bolt 10 protruding upward from the foundation concrete 3 and a lower end of the column 42 is joined to the upper surface 42a of the metal joint 42. The design base strength F1? Of the joint hardware 42 is smaller than the design reference strength F2 of the column member 4, and the bending strength Mu? Of the column base 41 is the design base strength. The value obtained by dividing F1? By the design reference strength F2 and calculated by multiplying the bending strength Mp of the column member 4 is smaller than the index bending strength Mp? Of the column member 4, and the load applied to the column base structure 40 increases. And the column base part 41 was made to yield before the column member 4.

Description

  In the present invention, a metal fitting arranged above the foundation concrete is joined to a column base fixed to a tip end portion of an anchor bolt protruding upward from the foundation concrete, and a lower end thereof is joined to the upper surface of the metal fitting. The present invention relates to a column base structure including a column member.

  4 to 6 are views referred to for explaining the conventional column base structure 2.

  As shown in FIG. 4, a conventional column base structure 2 includes a column base 5 provided on a foundation concrete 3 and a steel column 4 (the lower end of which is joined to a metal fitting 6 of the column base 5). Column member). The column base 5 had a metal joint 6, a mortar 8, an anchor bolt 10, nut members 12 and 14, a washer 16, and a fixing plate 18.

  As for the column base part 5 of the conventional column base structure 2, the flat joint metal fitting 6 which has both front and back surfaces was provided through the mortar 8 above the foundation concrete 3. FIG. The joining hardware 6 of the column base 5 is made of metal, and the lower end of the steel column 4 having a length in the vertical direction in the figure is joined to the upper surface 6a (surface) by welding.

  Here, in FIG. 4, for convenience of explanation, the welded portion W is not drawn on the front side surface of the steel column 4 in the figure, but the front side surface and the back side surface in FIG. Similar to the two side surfaces adjacent to the surface, the welded portion W is formed. This also applies to other drawings such as FIG. 5 and FIG.

  Then, the upper end portion of the anchor bolt 10 protruding upward from the foundation concrete 3 was inserted through the bolt insertion hole 6 b and the through hole of the washer 16 at the peripheral edge of the metal joint 6. The male screw portion formed at the upper end portion of the anchor bolt 10 is screwed to the female screw portion of the two nut members 12, so that the steel column 4 has the welded portion W, the joint metal 6 of the column base portion 5, and It was erected and fixed on the foundation concrete 3 through the mortar 8 (see, for example, Patent Document 1).

  Further, in the basic concrete 3, the male thread portion formed at the lower end portion of the anchor bolt 10 is loosely inserted into a through hole penetrating in the thickness direction of the fixing plate 18, and on the upper surface side and the lower surface side of the fixing plate 18. The fixing plate 18 is integrally fixed to the lower end portion of the anchor bolt 10 in the foundation concrete 3 by screwing the female screw portion of the nut member 14.

  Further, as another conventional column base structure, instead of the above-described joint metal 6, the bottom plate portion and the support plate formed in a trapezoidal shape with the center portion of the top surface of the bottom plate portion being higher than the peripheral edge portion. There is a column base structure using a metal joint different from a simple flat plate shape, in which the lower end of the steel column is joined by welding to the upper surface of the support base (see, for example, Patent Document 2).

  In another conventional column base structure according to Patent Document 2, an upper end portion of an anchor bolt protruding upward from the foundation concrete is inserted into a bolt insertion hole penetrating a thickness direction of a peripheral edge portion of a bottom plate portion of a joint metal fitting. Then, when the male screw part formed on the anchor bolt is screwed to the female screw part of the nut member, the steel column is placed on the foundation concrete via the welded part, the joint hardware and the mortar of the column base part. It was fixed in a standing position.

  By the way, the building structure provided with the conventional column base structure 2 (see FIG. 4) has a central portion between the pair of welded portions W with the joint hardware 6 on both sides of the steel column 4 as shown in FIG. When a load that generates a large bending moment M for rotating the steel column 4 around the rotation center O in the clockwise direction is applied, the steel column 4 and the column base 5 of the column base structure 2 Among them, the one with weak proof stress yielded first and plastically deformed.

In such a building structure having the conventional column base structure 2, in order to yield and plastically deform the column base 5 before the steel column 4, the proof strength against the bending moment M of the column base 5 is required. there was small Kusuru need than the yield strength of the steel columns 4.

  Here, the yield strength of the steel column 4 (including bending strength Mp and axial strength Np, which will be described later) is determined by the design reference strength F2 of the steel column 4, and the greater the design reference strength F2 of the steel column 4, the more the steel frame The proof stress of the pillar 4 was large.

  On the other hand, the proof stress of the column base 5 (including bending proof Mu and axial proof strength Nu described later) is not determined by the design reference strength F1 of the joint hardware 6, but the strength of the joint hardware 6 and the anchor bolt 10 And the fixing performance of the joint metal 6 with the foundation concrete 3 through the mortar 8, the anchor bolt 10, the nut members 12 and 14, the washer 16 and the fixing plate 18.

  In addition, the conventional column base structure 2 includes a column base structure 2A in which the design reference strength F1 of the metal fitting 6 is greater than or equal to the design reference strength F2 of the steel column 4, and the design reference strength F1 of the metal fitting 6 is the design standard of the steel column 4. When divided into two, the column base structure 2B having a strength smaller than the strength F2, the column base structure 2A has been widely used.

  Because, with respect to the steel column 4 in the conventional column base structure 2B, as shown in FIG. 6, it rotates clockwise around the center O of rotation between the center of the pair of welded portions W with the metal fitting 6 of the steel column 4 When a load that generates a large bending moment M that attempts to rotate the steel column 4 is applied in the direction, the weld W connecting the steel column 4 and the metal joint 6 between the column base 5 locally yields. As a result, the welded portion W is broken, and there is a concern that the metal fitting 6 between the steel column 4 and the column base 5 is separated from each other.

  On the other hand, as shown in FIG. 5, the steel column 4 in the conventional column base structure 2 </ b> A rotates clockwise around the rotation center O at the center between the pair of welded portions W with the metal fitting 6. When a load that generates a large bending moment M that tries to rotate the steel column 4 is applied in the direction, the welded portion W that connects the metal fittings 6 of the steel column 4 yields instead of yielding. Is bent in the clockwise direction at the portion above the welded portion W, so that there was no possibility that the welded portion W was broken and the joint 6 between the steel column 4 and the column base 5 was separated from each other.

  For this reason, in the conventional column base structure 2, the design reference strength F <b> 1 of the metal joint 6 is equal to or higher than the design reference strength F <b> 2 of the steel column 4.

  Moreover, the structural calculation of the building structure provided with the conventional column base structure 2 has been performed by a structural calculation apparatus using a structural calculation program.

  Here, the structural calculation program is the load data such as the scale and shape of the building structure, the material and dimensions of the beams and pillars that make up the column base structure in the building structure and the upper structure above, the fixed load and the load load. Based on the input data, etc., various strength tests, calculation of allowable stress, calculation by the Building Standards Act such as limit strength calculation, etc., and pass / fail judgment are performed continuously, and all the results are obtained. It is displayed and / or printed on the structural calculation device.

  Then, the conventional structural calculation device has values such as the bending strength Mp and the axial strength Np of the steel column 4 and the bending strength Mu and the axial strength Nu of the column base 5 from the data input by the conventional structural calculation program. Of the bending strength Mp of the steel column 4 and the bending strength Mu of the column base 5, the smaller one is set as the ultimate bending strength Ms of the column base structure 2, and this ultimate bending strength Ms is a criterion for pass / fail judgment. Used to calculate the structure of building structures.

JP 2003-232078 A JP 2003-336266 A

  In recent years, the strength of the steel column 4 has been increased, and a high strength material having a large design standard strength F2 has been used as the material of the steel column 4. For this reason, in order to make the design standard strength F1 of the metal joint 6 larger than the design standard strength F2 of the steel column 4, a high strength material having a large value of the design standard strength F1 must be used as the material of the metal joint 6. There is a problem that the manufacturing cost of the joining hardware 6 is increased and the manufacturing cost of the conventional column base structure 2 using the joining hardware 6 is also increased.

  Therefore, in view of the above problems, the present invention is such that when a load that generates a bending moment due to an earthquake or the like is applied, the joint between the metal joint and the column member locally yields and the joint breaks. It is an object of the present invention to provide a column base structure that can prevent the manufacturing cost of the joint hardware and the column base structure from being increased.

In order to solve the above problems, the column base structure according to the present invention is:
A metal joint disposed above the foundation concrete includes a column base fixed to an anchor bolt protruding upward from the foundation concrete, and a column member whose lower end is joined to the upper surface of the metal joint by welding. A column base structure provided,
The design standard strength of the joint hardware is smaller than the design standard strength of the column member,
The bending strength of the column base is calculated by multiplying the bending strength of the column member by a value obtained by dividing the design standard strength of the joint hardware by the design standard strength of the column member, based on the index bending strength of the column member. small,
As the load applied to the column base structure increases, the column base portion yields before the column member.

The column base structure according to the present invention is
The bonding hardware is formed in a plate shape having both front and back surfaces and an equal thickness.

The column base structure according to the present invention is
The joint hardware has both front and back surfaces, a bottom plate portion formed in a plate shape having an equal thickness, and a support base portion having a height upward from the periphery of the upper surface of the bottom plate portion. And the lower end part of the said column member is joined to the upper surface of this support stand part, It is characterized by the above-mentioned.

According to such a column base structure of the present invention,
A metal joint disposed above the foundation concrete includes a column base fixed to an anchor bolt protruding upward from the foundation concrete, and a column member having a lower end joined to the upper surface of the metal joint. A column base structure,
The design standard strength of the joint hardware is smaller than the design standard strength of the column member,
The bending strength of the column base is calculated by multiplying the bending strength of the column member by a value obtained by dividing the design standard strength of the joint hardware by the design standard strength of the column member, based on the index bending strength of the column member. small,
As the load applied to the column base structure increases, the column base portion yields before the column member,
When a load that generates a bending moment due to an earthquake or the like is applied, it is possible to prevent the joint between the joint metal and the column member from locally yielding and breaking the joint, and to join the metal joint and the column. An increase in the manufacturing cost of the leg structure can be prevented.

It is a partial cross section side view showing column base structure 40 concerning a 1st embodiment of the present invention. It is a conceptual side view for demonstrating the state to which the load which generates the bending moment M was added in the column base structure 40 shown in FIG. It is a partial cross section side view showing column base structure 70 concerning a 2nd embodiment of the present invention. It is a partial cross section side view which shows the conventional column base structure 2, 2A, 2B. It is a conceptual side view for demonstrating the state to which the load which generates the bending moment M was added in 2 A of conventional column base structures shown in FIG. It is a conceptual side view for demonstrating the state to which the load which generates the bending moment M was added in the conventional column base structure 2B shown in FIG.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the column base structure which concerns on this invention is demonstrated concretely based on drawing.

  FIG.1 and FIG.2 is a figure referred in order to demonstrate the column base structure 40 which concerns on the 1st Embodiment of this invention. Hereinafter, the same parts as those of the conventional column base structure 2 will be described with the same reference numerals, and the description of the same structure as the conventional one will be omitted except for a part.

  As shown in FIG. 1, the column base structure 40 according to the present embodiment has a column base 41 provided on the foundation concrete 3 and a lower end of the column base 41 joined to a metal fitting 42 of the column base 41. A steel column 4 (column member) is provided. The column base 41 includes a metal joint 42, a mortar 8, an anchor bolt 10, nut members 12 and 14, a washer 16, and a fixing plate 18.

  In the column base part 41 of the column base structure 40 according to the present embodiment, a flat joint metal 42 is provided above the foundation concrete 3 via the mortar 8. The metal joint 42 is made of metal and has square front and back surfaces.

  The metal fitting 42 of the column base 41 has its upper surface 42 a abutted against the lower end of the steel column 4 and is joined to each other by welding at the weld W. The steel column 4 has a length in the vertical direction in FIG. 1 and is formed in a hollow rectangular tube shape.

  Then, the upper end portion of the anchor bolt 10 protruding upward from the foundation concrete 3 is inserted into a bolt insertion hole 42 b formed in the peripheral edge portion of the joint hardware 42.

  The male thread portion formed at the upper end portion of the anchor bolt 10 that protrudes upward from the metal joint 42 passes through the through hole of the washer 16 and is screwed to the female thread portion of the nut member 12. Is fixedly erected on the foundation concrete 3 through the welded portion W, the metal joint 42 of the column base 41 and the mortar 8.

  In the column base structure 40 according to the present embodiment, the design reference strength F1 ′ of the metal joint 42 is smaller than the design reference strength F2 of the steel column 4.

  In the column base structure 40 according to the present embodiment, the bending strength Mu ′ of the column base portion 41 is smaller than the index bending strength Mp ′ of the steel column 4.

  Here, the bending strength Mu ′ of the column base 41 is the same as the bending strength Mu of the column base 5 in the conventional column base structure 2, the strength of the joining hardware 42, the strength of the anchor bolt 10, and the joining hardware 42. Of the mortar 8, anchor bolt 10, nut members 12 and 14, washer 16 and fixing plate 18, and is determined by the fixing performance with the foundation concrete 3.

  On the other hand, the index bending strength Mp ′ of the steel column 4 is obtained by multiplying the bending strength Mp of the steel column 4 by a value obtained by dividing the design standard strength F1 ′ of the metal joint 42 by the design standard strength F2 of the steel column 4. It is calculated.

  The column base structure 40 according to the present embodiment is configured so that the bending strength Mu ′ of the column base 41 is smaller than the index bending strength Mp ′ of the steel column 4 with respect to the steel column 4. 2, when a load that generates a large bending moment M is applied in the clockwise direction around the rotation center O of the central portion between the pair of welded portions W with the joint hardware 42, The welded part 42 yields and plastically deforms without the welded part W connecting the joined metallized 42 yielding locally and the welded part W breaking.

  Moreover, the structural calculation of the building structure provided with the column base structure 40 according to the present embodiment is performed by a structural calculation apparatus using a structural calculation program.

  That is, the structural calculation device used for the building structure including the column base structure 40 according to the present embodiment is configured to obtain the bending strength Mp and the axial strength Np of the steel column 4 from the data input by the structural calculation program. Is multiplied by a value obtained by dividing the design reference strength F1 ′ of the metal joint 42 by the design reference strength F2 of the steel column 4, and the index bending strength Mp ′, the index shaft strength Np ′ of the steel column 4, and the column base portion 41 are calculated. Values such as the bending strength Mu ′ and the axial strength Nu ′ are calculated.

  Then, the structural calculation device uses the structural calculation program to determine the ultimate bending strength Ms of the column base structure 40 as the smaller one of the index bending strength Mp ′ of the steel column 4 and the bending strength Mu ′ of the column base 41. As described above, the structural calculation of the building structure is performed using the ultimate bending proof stress Ms as a criterion for the pass / fail judgment.

  With such a structural calculation apparatus using the structural calculation program, the structural calculation is performed with the bending strength Mu ′ of the column base 41 smaller than the index bending strength Mp ′ of the steel column 4 as the ultimate bending strength Ms. The dimensions of each member of the building structure including the structure 40 are determined.

  Therefore, the column base structure 40 according to the present embodiment has the bending moment M due to the earthquake shown in FIG. 2 even if the design reference strength F1 ′ of the metal fitting 42 is smaller than the design reference strength F2 of the steel column 4. It is possible to prevent the welded portion W that connects the steel column 4 and the metal joint 42 from yielding locally and breaking the welded portion W when a load that generates the above is applied.

  In addition, since the design reference strength F1 ′ of the metal joint 42 can be made smaller than the design reference strength F2 of the steel column 4, it is assumed that a high-strength material having a large design reference strength F2 is used as the material of the steel column 4. However, it is not necessary to use a high-strength material having a large design reference strength F1 ′ as the material of the joint hardware 42.

  For this reason, the column base structure 40 according to the present embodiment can prevent an increase in the manufacturing cost of the joint hardware 42 and also prevent an increase in the manufacturing cost of the column base structure 40 using the joint hardware 42. can do.

  As described above, according to the column base structure 40 according to the first embodiment of the present invention, when a load that generates the bending moment M due to an earthquake or the like is applied, the joint hardware 42 and the steel column 4 It is possible to prevent the joint portion (welded portion W) from yielding locally and breaking the joint portion, and to prevent the manufacturing cost of the joint hardware 42 and the column base structure 40 from being increased. .

  FIG. 3 is a view referred to for explaining the column base structure 70 according to the second embodiment of the present invention.

  The column base structure 70 according to the present embodiment includes a bottom plate portion 72a and a support base portion 72d as shown in FIG. 3 instead of the joint hardware 42 in the column base structure 40 according to the first embodiment. The column base structure 40 according to the first embodiment is different from the column base structure 40 according to the first embodiment in that the metal fitting 72 is provided.

  That is, the metal joint 72 of the column base portion 71 in the present embodiment is made of metal, and as shown in FIG. 3, the bottom plate portion 72a formed in a plate shape having both substantially square front and back surfaces, and its bottom plate The center part of the upper surface 72b of the part 72a is comprised by the support stand part 72d which has height toward the upper direction in the figure from the peripheral part.

  The metal fitting 72 has the lower end of the steel column 4 abutted against the upper surface 72e of the support base 72d, and is joined to each other by welding at the weld W.

  Then, the upper end portion of the anchor bolt 10 protruding upward from the foundation concrete 3 is inserted into a bolt insertion hole 72 c formed in the peripheral edge portion of the bottom plate portion 72 a of the joint hardware 72.

  The male screw portion formed at the upper end portion of the anchor bolt 10 that protrudes upward from the peripheral edge portion of the bottom plate portion 72a of the metal fitting 72 passes through the through hole of the washer 16 and is screwed to the female screw portion of the nut member 12. Accordingly, the steel column 4 is erected and fixed on the foundation concrete 3 via the welded portion W, the joint metal 72 of the column base 71 and the mortar 8.

  In the column base structure 70 according to the present embodiment, the design reference strength of the joint hardware 72 is smaller than the design reference strength F2 of the steel column 4 as in the case of the column base structure 40 according to the first embodiment. Yes.

  In the column base structure 70 according to the present embodiment, the bending strength Mu ′ of the column base portion 71 is smaller than the index bending strength Mp ′ of the steel column 4.

  According to such a column base structure 70 according to the present embodiment, when a load that generates a bending moment M due to an earthquake or the like is applied, similarly to the column base structure 40 according to the first embodiment. In addition, it is possible to prevent the joint portion (welded portion W) between the joint hardware 72 and the steel column 4 from locally yielding and breaking the joint portion, and the joint hardware 72 has a high design reference strength value. Since it is not necessary to use a strength material, it is possible to prevent an increase in the manufacturing cost of the joint hardware 72 and the column base structure 70 having the same.

  In addition, this invention is not limited only to the said embodiment, If it is in the range which can achieve the objective of this invention, various changes are possible about a column base structure.

  For example, in the column base structure 40 according to the first embodiment, the case in which the metal joint 42 has a flat plate shape having both front and back surfaces in a substantially square shape has been described. A square other than the shape may be used.

  Further, the bonding hardware 42 may be a flat plate having both a polygonal shape other than a square and a circular front and back surfaces. This also applies to the bottom plate portion 72a of the metal joint 72 in the second embodiment.

  Further, in the column base structure 40 according to the first embodiment, the steel column 4 whose lower end portion is joined to the joining hardware 42 is formed in a rectangular tube shape, but is not limited to this shape. For example, it may be formed in a cylindrical shape. Moreover, the steel column may be formed in a solid shape.

  In addition, the building structure including the column base structure 40 according to the first embodiment is subjected to structural calculation by a structural calculation apparatus using a structural calculation program, whereby the dimensions and the like of each member are determined. However, the design reference strength F1 ′ of the metal joint 42 is smaller than the design reference strength F2 of the steel column 4, and the bending strength Mu ′ of the column base 41 is smaller than the index bending strength Mp ′ of the steel column 4. If so, a structural calculation program or a structural calculation apparatus need not be used.

2,2A, 2B Column base structure 3 Foundation concrete 4 Steel column 5 Column base 6 Joint metal 6a Upper surface 6b Bolt insertion hole 8 Mortar 10 Anchor bolt 12, 14 Nut member 16 Washer 18 Fixing plate 40 Column base 41 Column base 42 Joint metal 42a Top surface 42b Bolt insertion hole 70 Column base structure 71 Column base 72 Joint metal 72a Bottom plate part 72b Top surface 72c Bolt insertion hole 72d Support base 72e Upper surface F1 Design standard strength of joint metal 6 F1 'Design of joint metal 42 Reference strength F2 Design reference strength of the steel column 4 M Bending moment Mp Bending strength of the steel column 4 Mp 'Index bending strength of the steel column 4 Mu Bending strength of the column base 5 Mu' Bending strength of the column base 41 Np Steel column 4 Np 'Index strength of steel column 4 Nu Strength of shaft base 5 Nu' Strength of column base 41 Ms End of design Local bending strength W Welded part

Claims (3)

A metal joint disposed above the foundation concrete includes a column base fixed to an anchor bolt protruding upward from the foundation concrete, and a column member whose lower end is joined to the upper surface of the metal joint by welding. A column base structure provided,
The design standard strength of the joint hardware is smaller than the design standard strength of the column member,
The bending strength of the column base is calculated by multiplying the bending strength of the column member by a value obtained by dividing the design standard strength of the joint hardware by the design standard strength of the column member, based on the index bending strength of the column member. small,
When the load applied to the column base structure increases, the column base portion yields before the column member. The column base structure according to claim 1, wherein the joint hardware is formed in a plate shape having both front and back surfaces and an equal thickness. The joint hardware has both front and back surfaces, a bottom plate portion formed in a plate shape having an equal thickness, and a support base portion having a height upward from the periphery of the upper surface of the bottom plate portion. And the lower end part of the said column member was joined to the upper surface of this support stand part. The column base structure of Claim 1 characterized by the above-mentioned.

Images