TW201527627A - Column base structure - Google Patents

Abstract

A column base structure is provided that is capable of enhancing the energy absorption capability of the column base structure, thereby preventing the building structure from being damaged, broken and collapsed, and also preventing the column base structure and the building structure from being increased in size, weight and cost. The column base structure contains a junction fitting 42 joined to a lower end of a column member 4, the junction fitting 42 being fixed in a peripheral portion thereof with an anchor bolt 10 that protrudes upward from foundation concrete 3, the anchor bolt 10 yielding before the column member 4, a first bending moment Ma that initiates yield of the anchor bolt 10 being larger than a second bending moment Mb that initiates yield of the peripheral portion of the junction fitting 42, and being 1.5 times or less the second bending moment Mb.

Description

Column foot construction

The present invention relates to a joint hardware for joining a lower end portion of a structural member to a column member above a foundation concrete, and fixed to a front end portion of a foot bolt protruding upward from the foundation concrete, and a foot bolt The column structure of the column member is surrendered first.

12 to 15 are diagrams for reference to the conventional column structure 2 for reference.

As shown in Fig. 12, the conventional column structure 2 is provided above the foundation concrete 3 via a plaster 8 with a flat column hardware 6 having two sides of a substantially square shape. The column leg hardware 6 is made of metal, and the lower end surface 6a (surface) is joined to the lower end surface of the cylindrical column 4 (column member) by welding, and the steel column 4 has a length in the vertical direction in the drawing.

Further, the upper end portion of the foot bolt 10 which protrudes upward from the base concrete 3 is inserted into the bolt insertion hole 6b of the peripheral portion of the leg hardware 6 and the through hole of the gasket 16. The steel column 4 is erected and fixed to the foundation concrete 3 via the column hardware 6 and the mortar 8 by screwing the male screw portion formed at the upper end portion of the anchor bolt 10 with the female screw portion of the nut member 12. (For example, refer to Patent Document 1).

Further, in the base concrete 3, the male thread portion formed at the lower end portion of the anchor bolt 10 is screwed and fastened to the female thread portion of the nut member 14, and is screwed An anchor plate 18 is placed on the female member 14.

In addition, as other conventional column foot structures, a column foot structure different from the flat plate shape is used instead of the column foot structure of the column foot hardware 6, which is composed of a bottom plate portion and a center of the upper surface of the bottom plate portion. The portion is formed by a support base portion whose peripheral portion protrudes above, and the lower end surface of the steel column is joined to the upper surface of the support base portion by welding (for example, refer to Patent Document 2).

Another conventional leg structure of this Patent Document 2 is a bolt insertion hole that is inserted into the thickness direction of the peripheral portion of the bottom plate portion of the leg hardware by inserting the upper end portion of the foot bolt protruding from the base concrete into the upper portion. And the male thread portion formed on the anchor bolt is screwed with the female thread portion of the nut member, and the steel column is erected and fixed on the foundation concrete via the column hardware and the plaster.

Further, for example, in the direction of the clockwise rotation of the center of rotation O of the joint between the steel column 4 and the column hardware 6 as shown in FIG. 13 due to an earthquake or the like, the steel column 4 in the above-described column structure 2 is used. In the case where a load is generated which generates a large bending moment M which is intended to rotate the steel column 4, the bending moment M causes the left end portion of the column hardware 6 to float upward.

On the other hand, the foot bolt 10 fixed to the left side of the rotation center O of the leg hardware 6 cannot be completely resisted against the load of the bending moment M, and the length itself is oriented toward the figure. The upper side is elongated (plastically deformed) to absorb the energy generated by the load of the bending moment M described above.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-232078

Patent Document 2: Japanese Patent Laid-Open Publication No. 2003-336266

However, as shown in FIG. 14, in the above-described column structure 2, since the foot bolt 10 after the plastic deformation is removed after the load for generating the bending moment M described above, it remains in the upper direction in the same figure. The state thus creates a large gap S between the lower surface of the nut member 12 and the upper surface of the gasket 16.

Therefore, when the load for generating the bending moment M described above is applied again, there is a problem that the energy absorption capability of the conventional column structure 2 is remarkably lowered as compared with the case where the load for generating the bending moment M is applied for the first time.

The problem of the conventional column structure 2 will be described in detail using Figs. 12 to 15 . Here, FIG. 15 is a hysteresis map (hysteresic characteristic map) schematically showing the correspondence relationship between the bending moment M (refer to FIG. 13) in the conventional column structure 2 and the rotation angle θ of the steel column 4, The bending moment M is applied to the steel column 4, and the rotation angle θ is a rotation angle of the steel column 4 from the up-and-down direction through a point chain (refer to FIG. 13) of the rotation center O of the joint portion of the column hardware 6. .

The conventional column structure 2 is set such that the value of the yielding starting bending moment when the foot bolt 10 starts to yield is higher than the value of the yielding starting bending moment when the steel column 4 starts to yield, and the peripheral portion of the column hardware 6 is subjected to When the force of the foot bolt 10 starts to yield, the value of the yield starting bending moment is smaller, and the anchor bolt 10 is yielded earlier than the steel column 4 and the column hardware 6.

Therefore, when the bending moment M acts on the column structure 2 shown in FIG. 12, the steel column 4 and the column hardware 6 are inclined such that the left side in FIG. 13 is upward toward the upper side, so that the center of rotation O in the same figure Close to the left foot bolt 10, The column foot hardware 6 is subjected to a load that generates a bending moment M, and is elongated toward the upper side in the drawing.

Here, the foot bolt 10 on the left side in FIG. 13 is between the state A and the state B in FIG. 15, and the length dimension thereof is elongated by the elastic deformation, but in the same figure, from the state B to the state C. When it exceeds its elastic range, it begins to yield, and its length dimension is elongated by plastic deformation to become large.

If the bending moment M is small, the left side anchor bolt 10 in FIG. 13 is between the state C and the state D in FIG. 15, and the length dimension is reduced to correspond to the portion elongated by elastic deformation, but in the same figure. The portion which is elongated by the plastic deformation from the state B to the state C remains in the original state in which the length is elongated even if the state C comes between the states E.

Further, when the bending moment acting in the opposite direction to the bending moment M (counterclockwise direction in FIG. 13) is applied, in the process from the state E to the state I via the states F, G, and H in FIG. 15, except for the bending moment The direction of action is reversed, and the rest are the same as the process from state A to state E in the same figure.

Therefore, the foot bolt 10 on the right side in FIG. 13 is the same as the foot bolt 10 on the left side in FIG. 13 from the state E through the states F, G, and H in FIG. 15, and is generated in FIG. The deformation in the process from state A to state E is the same.

The area of the quadrilateral formed by the trajectory from the state A to the state E in Fig. 15 and the area of the quadrilateral formed by the trajectory from the state E to the state I show that the conventional column structure 2 can be in these states. The amount of energy absorbed between absorptions. Therefore, from the state A to the state I, the conventional column structure 2 can perform energy absorption without problems.

However, once the state I in FIG. 15 is reached, as shown in FIG. 14, since each of the foot bolts 10 on the left and right sides in the drawing has been elongated to the upper side in the figure by plastic deformation, the leg hardware 6 becomes It is no longer in a state of being fixed to the anchor bolt 10, and a large gap S is generated between the lower surface of the nut member 12 and the upper surface of the gasket 16.

And, when the load generating the bending moment M is again applied to the state I, the steel is in contact with the surface of the upper surface of the nut member 12 from the state I to the state J, that is, until the left side in FIG. The column 4 and the column hardware 6 are inclined such that the left side of the figure is more upward and higher than the right side.

Since the load for generating the bending moment M from the state I to the state J is not transmitted from the lower end of the steel column 4 and the column hardware 6 to the foot bolt 10, the conventional column structure 2 is Between state I and state J, there is a slip phenomenon in which energy absorption is not performed at all.

At this time, in the conventional column structure 2, the lower end of the steel column 4, the column hardware 6 and the foot bolt 10 do not absorb energy, so the load of the bending moment M is generated from the state I to the state J. It is not reduced at all, but is applied violently to the beam member, the column member, and the like which constitute the upper structure above the column structure 2.

Therefore, the load causing the bending moment M described above is not reduced at all, and there is a fear that the beam member and the column member constituting the upper structure are damaged or broken, and the building structure is collapsed due to the rapid application of the load.

In response to such a problem, the upper structure above the column structure 2 is increased or thickened by the diameter or thickness of the beam member and the column member, thereby bearing the load of generating the bending moment M, but Come over, this will bring about the problem of large-scale, heavy-weight and high-priced upper structure.

In addition, in the conventional column structure 2, in order to increase the energy of the bending moment M which can be absorbed by the foot bolt 10, in the case of using the foot bolt 10 which increases the outer diameter size, not only the corresponding nut member 12 is used. The size also needs to be increased, and the thickness of the column hardware 6 needs to be increased, which causes a problem of increasing the size, weight, and price of the column structure 2.

Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a column structure which can improve the energy absorbing ability of a column structure, prevent damage, breakage, or collapse of a building structure, and can prevent column structure and construction. The structure is large, heavy, and expensive.

In order to solve the above problems, the column structure of the present invention fixes the peripheral edge portion of the joint hardware joined to the lower end portion of the column member by the foot bolt protruding upward from the foundation concrete, and the above-mentioned foot bolt is more than the above The column member first generates a fall, and the first bending moment at which the foot bolt starts to generate a fall is set to be greater than a second bending moment at which a peripheral portion of the joint hardware starts to fall, and the second bending moment is 1.5 times or less.

According to the column structure of the present invention, the column structure is fixed by the foot bolt of the lower end portion of the column member by the foot bolt protruding upward from the foundation concrete, and the above-mentioned anchor bolt is more than the above The column member first yields, wherein the first bending moment at which the foot bolt starts to yield is set to be larger than a second bending moment at which the peripheral edge portion of the joint hardware starts to yield, and is the second bending moment 1.5 times or less, thereby improving the energy absorption capacity of the column structure, preventing damage, breakage, or collapse of the building structure, and preventing the column structure and the structure of the structure from being enlarged, weighted, and expensive. .

2, 40‧‧ ‧ column foot structure

3‧‧‧Basic concrete

4‧‧‧ steel column

6, 42‧‧‧ column foot hardware

6a, 42a‧‧‧ upper surface

6b, 42b‧‧‧ bolt insertion holes

8‧‧‧ Stucco

10‧‧‧foot bolts

12, 14‧‧‧ nut components

16‧‧‧Washers

18‧‧‧ anchor plate

42c‧‧‧Bend

50‧‧‧2 layer model

52‧‧‧4 layer model

53‧‧‧Fundamental

54‧‧‧column components

56‧‧‧beam components

58‧‧‧ joints

60‧‧‧ column foot

A~L, N‧‧‧ Status

a, b, c‧‧‧ buildings

M‧‧‧ bending moment

Ma, Mb‧‧‧ yielding starting bending moment

O‧‧‧ Rotation Center

Q‧‧‧ area

S, S1‧‧ ‧ gap

Θ‧‧‧ angle

Fig. 1 is a partial side cross-sectional view showing a column structure 40 according to an embodiment of the present invention.

FIG. 2 is a partial side cross-sectional view for explaining a state in which a bending moment M is applied to the leg structure 40 shown in FIG. 1.

3 is a partial side cross-sectional view for explaining a state in which a bending moment M is applied to the column structure 40 shown in FIG. 1 and the foot bolt 10 is yielded.

Fig. 4 is a hysteresis diagram schematically showing the relationship between the bending moment M of the steel column 4 of Fig. 1 and the rotation angle θ.

FIG. 5 is a schematic diagram of a 2-layer model 50.

FIG. 6 is a schematic diagram of a 4-layer model 52.

Fig. 7 is a hysteresis diagram showing the relationship between the bending moment M of the steel column 4 in Fig. 12 and the rotation angle θ.

Fig. 8 is a hysteresis diagram showing the relationship between the bending moment M of the steel column 4 of Fig. 1 and the rotation angle θ.

Fig. 9 is a hysteresis diagram schematically showing the relationship between the bending moment M of the steel column 4 and the rotation angle θ when the steel column 4 of Figs. 1 and 12 is joined to the base concrete 3 by the embedded column foot.

Figure 10 is a two-layer model of a conventional column structure 2 and a column structure 40 of the present invention. A comparison chart of the energy absorption index of the column foot in 50.

Figure 11 is a graph comparing the column absorption energy indices in the conventional column structure 2 and the 4-layer model 52 of the column structure 40 of the present invention.

Figure 12 is a partial side cross-sectional view showing a conventional leg structure 2.

Fig. 13 is a partial side cross-sectional view for explaining a state in which a bending moment M is applied to the column structure 2 shown in Fig. 12.

Fig. 14 is a partial side cross-sectional view for explaining a state in which a bending moment M is applied to the column structure 2 shown in Fig. 12 and the foot bolt 10 is yielded.

Fig. 15 is a hysteresis diagram schematically showing the relationship between the bending moment M of the steel column 4 of Fig. 12 and the rotation angle θ.

Hereinafter, the form of the column structure for carrying out the present invention will be specifically described based on the drawings.

1 to 11 are views for explaining the column structure 40 according to an embodiment of the present invention. Hereinafter, the same portions as those of the above-described column structure 2 will be denoted by the same reference numerals, and a part of the same configuration as the above-described conventional structure will be omitted.

As shown in Fig. 1, the column structure 40 of the present embodiment is provided with a flat column leg hardware 42 (joining hardware) via the plaster 8 above the foundation concrete 3. The column foot hardware 42 is made of metal and has two sides in a square shape.

The column foot hardware 42 is joined by abutting the lower end surface of the steel column 4 (column member) to the upper surface 42a thereof and by welding. The steel column 4 has a length in the vertical direction in Fig. 1 and is formed in a hollow cylindrical shape.

And, a foot bolt protruding from the base concrete 3 toward the upper side thereof The upper end portion of the 10 is inserted into the bolt insertion hole 42b formed in the leg hardware 42.

The male screw portion formed at the upper end portion of the anchor bolt 10 protruding upward from the column hardware 42 is inserted into the through hole of the washer 16 and screwed to the female screw portion of the nut member 12, thereby being passed through The column foot hardware 42 and the stucco 8 erect the steel column 4 to the foundation concrete 3.

The leg hardware 42 of the present embodiment is set to have a thickness thinner than the thickness of the conventional leg hardware 6, so that the peripheral portion of the leg hardware 42 is subjected to yield by the force of the foot bolt 10. The yield start bending moment Mb (second bending moment) is smaller than the yield starting bending moment when the peripheral portion of the leg hardware 6 of the conventional column structure 2 is subjected to the yield by the force of the foot bolt 10.

Further, the leg structure 40 of the present embodiment is set such that the yield start bending moment Ma (first bending moment) when the foot bolt 10 starts to yield, and the peripheral edge portion of the leg hardware 42 is received by the foot bolt 10 The yield starting bending moment Mb at the time of starting to yield is large, and is a value equal to or less than 1.5 times the yield starting bending moment Mb.

Therefore, if the load causing the bending moment increases, the peripheral portion of the leg hardware 42 starts to yield before the foot bolt 10.

On the contrary, in the case where the yield start bending moment Ma when the foot bolt 10 starts to yield is equal to or less than the value of the yield start bending moment Mb when the peripheral portion of the leg hardware 42 starts to yield, if the load is generated with the bending moment When the foot bolt 10 is enlarged, the foot bolt 10 will yield first, so that the problem of the conventional column structure 2 cannot be solved.

Further, in the case where the yield starting bending moment Ma when the foot bolt 10 starts to yield is larger than the value of 1.5 times the yield starting bending moment Mb when the peripheral portion of the leg hardware 42 starts to yield, the foot bolt 10 yields. Before plastic deformation, The plastic deformation of the column foot hardware 42 is excessively advanced, and the portion of the column foot hardware 42 fixed by the foot bolt 10 and its periphery are bent more than necessary, and it is feared that the foot bolt 10 is pressed in a direction not in the direction in which it is elongated. , causing the foot bolt 10 to break.

Further, the yield starting bending moment when the column member 4 starts to yield is set to be greater than the value of the yield starting bending moment Ma when the foot bolt 10 starts to yield, and the peripheral portion of the leg hardware 42 is received by the anchor bolt 10 The value of the yield starting bending moment Mb when the force starts to yield, and the value of the yield starting bending moment when the yielding of the column foot hardware 42 starts to yield is greater, so that the column member 4 is not more than the foot bolt 10 and the column foot. The hardware 42 first yields and plastically deforms.

Further, the base concrete 3 and the mortar 8 start to compress and yield the bending moment at the time of yielding, and are set to be a bending start moment at the peripheral edge portion of the leg hardware 42 by the force of the foot bolt 10 to start yielding. The value of Mb is greater than that so that the base concrete 3 and the stucco 8 are not plastically deformed by the compression and compression of the column foot 42 first.

The leg structure 40 of the present embodiment applies a large bending moment M to the steel column 4 in a direction that rotates clockwise around the center of rotation O of the joint portion with the leg hardware 42 as shown in FIG. In the case of the load, from the state B to the state C in Fig. 4, the peripheral portion near the bolt insertion hole 42b on the left side in Fig. 2 of the leg hardware 42 is received by the nut member 12 attached to the anchor bolt 10. The force is yielded and plastically deformed, so that the left end portion of the leg hardware 42 on the left side of FIG. 2 is bent more than the portion of the plastic deformation. The glyph comes to a position below the lower side of the plastically deformed portion.

This column foot hardware 42 The character-shaped bent portion is folded back into a substantially linear shape in the horizontal direction when a load of a bending moment in a counterclockwise direction opposite to the bending moment M is applied from the state F to the state G in Fig. 4 . .

Further, the leg hardware 42 to which the load of the bending moment M in the above-described clockwise direction of rotation is applied is applied, and the right portion in Fig. 2 is yielded by the force of the upper surface of the mortar 8 pressed against the base concrete 3 Deformation, such that the portion of the plastic deformation is bent against the right end of the leg hardware 42 on the right side of the figure, and is bent in the opposite direction Glyph.

Further, the foot bolt 10 on the left side in Fig. 2, when in the state B to the state C in Fig. 4, yields beyond its elastic range, and its length dimension is increased by plastic deformation to become large.

In the process from the state E in FIG. 4 to the state I via F, G, and H, except for the direction in which the bending moment acts in the opposite direction, the rest is the same as the process from the state A to the state E in the same figure.

Therefore, the foot bolt 10 on the right side in FIG. 2 is in the process from the state E in FIG. 4 to the state I via F, G, and H, and the foot bolt 10 on the left side in FIG. 2 is generated from FIG. State A undergoes the same deformation in the process of reaching state E via B, C, and D.

Further, in the process from the state E in FIG. 4 to the state I via F, G, and H, the left side portion of the leg hardware 42 in FIG. 2 is pressed against the upper surface of the plaster 8 on the foundation concrete 3. The force is yielded and plastically deformed, so that the portion of the plastic deformation is bent against the left end portion of the leg hardware 42 on the left side in the figure, and is bent in the opposite direction. Glyph.

3 shows the column structure 40 of the state I and the state J in FIG. 4, except that the left and right end portions of the column foot hardware 42 are each formed with a curved portion 42c bent toward the upper side in the drawing, so the nut member 12 Lower surface and curved portion 42c of column foot hardware 42 The gap S1 between the upper surfaces of the washers 16 is significantly smaller than the gap S of the conventional leg structure 2.

Therefore, in the case where the state I is again applied with the load generating the bending moment M, since the lower surface of the nut member 12 on the left side in Fig. 3 is substantially in direct contact with the upper surface of the gasket 16 on the curved portion 42c of the leg hardware 42 Therefore, it is not easy to produce a slip phenomenon as in the conventional column structure 2.

Thus, the load generating the bending moment M can be substantially directly transmitted from the lower end portion of the steel column 4 and the column hardware 42 to the foot bolt 10, and therefore, the column structure 40 is from the state J to the state K in FIG. Advancing along a trajectory that approximates substantially elastic deformation allows energy absorption of the lower end of the steel column 4, the column hardware 42 and the foot bolt 10.

Therefore, the load which generates the above-mentioned bending moment M is not applied to the beam member and the column member which constitute the upper structure above the column structure 40, and the upper structure above the column structure 40 can bear only the load. Part of it.

In other words, the column structure 40 of the present embodiment can perform energy absorption corresponding to the area Q portion of the triangle (hatched portion) formed by the trajectory of the state J via K and L from the state J in Fig. 4, thereby The foot bolt 10 can be loaded from the lower end portion of the steel column 4 and the column hardware 42 to generate the above-mentioned bending moment M.

Hereinafter, tests performed on the conventional column structure 2 and the column structure 40 of the present embodiment will be described with reference to Figs. 5 to 11 . In the above test, a seismic wave (EL CENTRO (NS) seismic wave) was applied to the two-layer model 50 shown in FIG. 5 and the four-layer model 52 shown in FIG. 6 under the condition that the load has a predetermined weight.

As shown in FIG. 5, the two-layer model 50 is provided with three column members 54 spaced apart from each other in the left-right direction in the drawing, and these column members 54 are erected via the leg portions 60. On the base surface 53.

Further, four beam members 56 are disposed substantially horizontally with respect to the base surface 53 and two of them are arranged in series and divided into two stages. The beam members 56 are rigidly joined to the column member 54 by the joint portions 58 that are abutting on the side portions of the column members 54 at both end portions in the longitudinal direction.

As shown in FIG. 6, the four-layer model 52 is similar to the two-layer model 50, and three column members 54 are arranged at intervals in the left-right direction in the drawing, and these column members 54 are erected on the base surface via the leg portions 60. 53 on.

Further, eight beam members 56 are disposed substantially horizontally with respect to the base surface 53 and two of them are arranged in series in the vertical direction and divided into two stages. The beam members 56 are rigidly joined to the column member 54 by the joint portions 58 that are abutting on the side portions of the column members 54 at both end portions in the longitudinal direction.

Fig. 7 is a hysteresis diagram showing the relationship between the bending moment M of the steel column 4 shown in Fig. 13 and the rotation angle θ, which are based on the use of the conventional column structure 2 for the column foot 60 of the 2-layer model 50. The results of the test were obtained. As shown in Fig. 7, in the conventional column structure 2, the slip phenomenon shown in the state I to the state J in Fig. 15 is generated.

On the other hand, FIG. 8 is a hysteresis diagram showing the relationship between the bending moment M of the steel column 4 shown in FIG. 2 and the rotation angle θ. These relationships are based on the column structure 40 of the present embodiment for the 2-layer model 50. The column foot 60 was obtained as a result of the test. As shown in Fig. 8, in the column structure 40 of the present embodiment, unlike the conventional column structure 2, the slip phenomenon shown in the state I to the state J in Fig. 15 is not generated.

Here, although FIG. 8 shows that the yielding start bending moment Ma at which the foot bolt 10 starts to yield is set to the yield start curve of the peripheral portion of the leg hardware 42 The 1.5 times of the bending moment Mb is the same as that of FIG. 8 when the yield starting bending moment Ma is larger than the yield starting bending moment Mb and is set within the range of the insufficient yield starting bending moment Mb.

Further, the leg structure 40 used in the above test is changed so that the yield starting bending moment Mb of the peripheral portion of the leg hardware 42 is within the above range, and is smaller than the peripheral portion of the leg hardware 6 of the conventional leg structure 2. The value of the yielding start bending moment is smaller, and the conditions are the same as those of the conventional column structure 2.

Further, the four-layer model 52 also shows the same tendency as the two-layer model 50 shown in FIGS. 7 and 8.

10 and 11 are views for comparing the column absorption energy index (W1/W0) of the conventional column structure 2 and the column structure 40 of the present embodiment. Fig. 10 shows a comparison of the column absorption energy indexes in the case of the 2-layer model 50, and Fig. 11 shows a comparison of the column absorption energy indexes in the case of the 4-layer model 52.

The column energy absorption index herein refers to the exposed column foot absorption energy W1 which can be absorbed by the conventional column foot structure 2 or the column foot structure 40 of the present embodiment, so that the column member 54 embedded in the column foot can If the absorbed absorption of the buried column foot is divided by W0 and is not dimensioned, the larger the value of the energy absorption index of the column foot, the more energy can be absorbed by the column foot absorbed by the column foot structure.

9 is a view showing a bending moment M and a rotation angle θ of the column member 54 in the case where the column member portion 54 of the column member 54 is not buried below the base surface 53 without using the column member 54 of the embedded column leg. The hysteresis graph of the relationship.

The column member 54 of the embedded column foot can perform energy absorption corresponding to the area of the quadrilateral formed by the trajectory from the state B in the same figure to the state B via C, D, E, and F, and the energy is buried. The column foot absorption energy W0. On the other hand, the exposed column absorption energy W1 is calculated based on the hysteresis diagram of the conventional column structure 2 shown in FIGS. 7 and 8 or the column structure 40 of the present embodiment.

In the case of the two-layer model 50 shown in FIG. 10, each of the three buildings a, b, and c of the conventional column structure 2 has a column energy absorption index value of 0.25 or less. Each of the three buildings a, b, and c of the column structure 40 of the embodiment has a column energy absorption index of 0.5 or more.

Here, each of the three buildings a, b, and c sets the strength of the column member and the beam member to be different from other buildings.

In the case of the four-layer model 52 shown in FIG. 11, each of the three buildings a, b, and c of the conventional column structure 2 has a column energy absorption index value of 0.15 or less. Each of the three buildings a, b, and c of the column structure 40 of the embodiment has a column energy absorption index of 0.3 or more.

As shown in FIGS. 10 and 11, the leg structure 40 of the present embodiment can increase the energy absorbed by the leg as compared with the conventional leg structure 2.

As shown in FIG. 3, in the leg structure 40 of the present embodiment, since the bent portions 42c are formed at the left and right end portions of the leg hardware 42, the lower surface of the nut member 12 attached to the anchor bolt 10 can be reduced. A gap S1 between the upper surfaces of the washers 16 on the bent portion 42c of the leg hardware 42.

Further, as shown in FIG. 4, the leg structure 40 of the present embodiment can increase the energy absorbed by the column structure 40 even after the foot bolt 10 yields.

That is, in the column structure 40 of the present embodiment, since the slip phenomenon of the column structure 2 as in the prior art is not generated, one of the loads of the bending moment M is generated. A portion is applied to the lower end portion of the steel column 4, the column hardware 42 and the foot bolt 10, so that the load causing the bending moment M described above is not all applied to the beam member and the column member which constitute the upper structure above the column structure 40. Alternatively, the upper structure above the column foot structure 40 can be used to bear only a portion of this load.

Therefore, it is possible to prevent damage or breakage of the beam member and the column member which constitute the upper structure above the column structure 40, collapse of the building structure, and prevent the size and weight of the column member and the beam member which constitute the upper structure. And high prices.

Further, in the column structure 40 of the present embodiment, the foot bolt 10 having a large outer diameter can be omitted, so that the foot bolt 10 and the column hardware 42 constituting the column structure 40 can be prevented from being enlarged and weighted. High price.

Therefore, as described above, according to the column structure 40 of the present embodiment, the energy absorbing ability of the column structure 40 can be improved, damage, breakage, or collapse of the building structure can be prevented, and the column structure 40 and the building structure can be prevented. The size of the object is increased, the weight is increased, and the price is increased.

Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made to the column structure as long as the object of the present invention can be achieved.

For example, in the leg structure 40 of the above-described embodiment, the case where the leg hardware 42 has a square shape having a square shape on both sides is described. However, the front and back sides may have a square shape having different lengths in the vertical and horizontal directions. Four squares outside.

Further, the column foot hardware may be formed of a base portion and a support portion in which the center portion of the upper surface of the bottom plate portion protrudes upward from the peripheral edge portion, or other shapes, as in the leg hardware of Patent Document 2 described above.

Further, in the column structure 40 of the above-described embodiment, the steel column 4 whose lower end surface is joined to the column hardware 42 is formed in a rectangular tube shape, but is not limited to this shape. It may also be formed in a cylindrical shape. In addition, the steel column can also be formed as solid.

Further, in the leg structure 40 of the above-described embodiment, the male screw portion formed at the upper end portion of the anchor bolt 10 is protruded and fixed to the upper side of the one nut member 12 than the leg hardware 42 protrudes upward. The threaded portion may be attached to two or more nut members 12 (double nuts, etc.).

Further, in the leg structure 40 of the above-described embodiment, in the base concrete 3, the male screw portion formed at the lower end portion of the anchor bolt 10 is screwed and fastened to the female screw portion of the one nut member 14, but it is also possible Two or more nut members 14 are attached, and the anchor plate 18 may be provided between the two nut members 14.

3‧‧‧Basic concrete

4‧‧‧ steel column

8‧‧‧ Stucco

10‧‧‧foot bolts

12‧‧‧ nut components

14‧‧‧ nut components

16‧‧‧Washers

18‧‧‧ anchor plate

40‧‧‧ column foot structure

42‧‧‧ column foot hardware

42a‧‧‧Upper surface

42b‧‧‧Bolt insertion hole

42c‧‧‧Bend

S1‧‧‧ gap

Claims (1)

A column foot structure for fixing a peripheral portion of a joint hardware joined to a lower end portion of a column member by a foot bolt protruding upward from the base concrete, and the foot bolt is firstly lowered than the column member; The first bending moment at which the foot bolt starts to fall is set to be larger than a second bending moment at which the peripheral portion of the joint hardware starts to fall, and is 1.5 times or less of the second bending moment.