JP2809590B2 - Connection between steel column and pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint between a steel column and a pile having a structure in which a steel column rises directly from a pile head. Used. In addition, for example, the present invention can also be applied to a column pile joint in a building straddling a river or a road.

[0002]

2. Description of the Related Art As a conventional column-pile joint portion of a building utilizing above the track, there is known a structure having the following structure.

[0003] (1) Conventional technology of column-pile joints in a one-pillar one-pile foundation structure used above a railway track [0003] Of a one-pillar one-pile foundation structure used above a railway track, FIG.
As shown in (a), in a low-rise railway over-the-air building with a floor number of 4 or less and a height of about 20 m or less from the ground surface, the column-pile joint is as shown in Figs. 21 (b) and (c). And steel column 22
Is embedded in the reinforced concrete pile 21. In the figure, reference numeral 23 denotes an existing track.

[0004] In this case, the design method of the column pile joint is already established through experiments and the like, and there are many embodiments.

[0005] As shown in Fig. 22 (a), a one-pillar, one-pile foundation structure is used above a railway track, and its height is 4
In a building utilizing a mid-to-high-rise railway above 5 m or less, the column-pile joint is, for example, as shown in FIGS.
Embedded in the concrete-filled steel pipe pile 31 using

In this case, the design method of the column-pile joint has already been established through experiments and the like. Further, as an improved column-pile joint, Japanese Patent Application Laid-Open No. 3-51428 discloses a steel pipe 33 provided with a reinforcing member which is continuous in a circumferential direction in a cross section in a predetermined upper portion of a steel pipe 33 having an inner surface projection. .

(2) Conventional technology related to steel tube-covered column-wound column bases, for example, Hozumi, Hirayama, Kato, Hirano; "Proposal of a column-wound column base covered with steel columns and its performance test. Part 1. Preliminary test and experimental plan ”, Architectural Institute of Japan Annual Meeting Abstracts (Kinki)
In October 1987, a structure is shown in a column-wound column base, in which the outer periphery of the reinforced concrete at the root-wound portion is covered with a square steel pipe, thereby eliminating the shear reinforcement and the formwork.

[0008] This steel pipe-covered column-wound column pedestal is different from the conventional column-wound column-based pedestal shown in FIG.
It has been found that despite the low root height, the steel pipe restrains the concrete and has both satisfactory strength and rigidity.

In addition, it has been concluded that the anchoring of the main bending bar is important in the root-wound column base.

FIGS. 24 (a) and 24 (b) show how the conventional root-winding type column base and steel pipe-covered root-winding type column base break, respectively, and FIG. 24 (c) shows a cross section of the coated steel pipe. It shows the shape. In FIGS. 23 and 24,
Reference numeral 41 denotes a base-winding column base, 41a denotes a coated steel tube, 42 denotes a steel column, 43 denotes concrete, 44 denotes a main reinforcing bar, 45 denotes a band bar, 46 denotes a foundation beam, and 47 denotes an anchor bolt.

(3) Prior art related to embedded column bases When the clearance distance (the distance from the outer surface of the steel column to the outer surface of the concrete of the pile) is small in the embedded type column base, the bearing pressure of the concrete is reduced. In some cases, it cannot be expected completely, and the lack of proof stress, rigidity and deformability is a problem.

FIG. 25 shows an embedded column base of a steel pipe concrete column by a double pipe system (Kamura, Sawada, Matsumura, Nakamura; "Regarding an embedded column base of a steel pipe concrete column by a double pipe system"). Experimental Research (Part 1) Strength Mechanism and Evaluation Method ”, Architectural Institute of Japan Annual Meeting Abstracts (Kanto), October 1988).

In this method, another rectangular steel pipe (outer pipe 5) is provided on the outside of the rectangular steel pipe concrete pillar 52 with an inner rib.
It has a double-pipe structure having 3).

The column stress is transmitted through the adhesion between the rectangular steel pipe 52a with the inner ribs and the grout mortar 54, and the column 52 and the outer pipe 53 are integrated until the end. That is, the pillar having the diameter of the outer tube 53 is embedded in the reinforced concrete foundation beam 51. A foundation beam 51 is attached to this outer tube 53
The main reinforcements and reinforcements are joined by welding, U-shaped reinforcement, or the like to form a bearing mechanism that does not expect the bearing strength of the exposed concrete 51a at the base end.

The method of constructing the column base is to set a square steel pipe to be an outer pipe at the same time as the reinforcement of the base part, and to cast the concrete of the base part while leaving the inside of the steel pipe. The work can be done after the foundation beam concrete is cast, so the construction is streamlined.

[0016]

SUMMARY OF THE INVENTION In the case of a one-pillar-one-pile foundation structure that is used above a railway track, a pile that generates a large bending moment is designed with a steel-pipe-cast-in-place concrete pile excellent in large bending strength and deformation performance. I was

In this case, if the axial load per column is large, a cast-in-place concrete pile having a larger cross section is required, but the design is difficult due to restrictions on the production of the steel pipe with inner projections. There is.

Further, as will be described later in detail in the section of operation, if the clearance distance of concrete is small, there is a problem that the concrete at the joint portion is prematurely damaged by punching shear due to the supporting force from the steel column.

An object of the present invention is to solve the above-mentioned problems, and to provide a joint between a steel column and a pile excellent in mechanical performance mainly in a building used above a middle-high-rise railway.

[0020]

SUMMARY OF THE INVENTION The present invention relates to a joint between a steel column and a pile, in which the lower part of the steel column is embedded in concrete at the head of the pile, and the entire outer periphery of the pile or a part of the outer periphery is provided with an outer peripheral reinforcing steel plate. And the steel column and the outer peripheral reinforcing steel plate are connected by a stiffener material.

The piles targeted by the present invention are reinforced concrete piles, steel reinforced concrete piles, and other composite piles composed of steel and concrete (hereinafter, referred to as composite piles including reinforced concrete piles). While constraining the concrete of the pile from the outside, it bears part of the bending moment transmitted from the steel column to the composite pile,
Further, in a portion where a clearance distance where punching shear or the like becomes a problem is short, the stiffener material is used to connect the steel column and the outer peripheral reinforcing steel plate to increase the fracture resistance.

As the outer peripheral reinforcing steel plate, a steel plate with projections (such as a striped steel plate formed by rolling) having projections on the inner surface is used as a slip stopper, or a shear connector such as a stud dowel is implanted. The pile can be integrated with concrete.

In addition, regarding the installation section in the axial direction of the column of the outer peripheral reinforcing steel plate and the pile material, Y ≧ L (L: column steel frame embedded length) from the top end of the pile in order to ensure the seismic safety of the joint. However, depending on the design, it may be shallower or provided over the entire length of the pile.

As the stiffener material, a steel plate is usually used, but other shapes such as a channel steel and an angle steel or an assembled material may be used.

The arrangement of the stiffener material can be considered to be provided in the entire embedding section below the steel column or in only a part of the section. Further, it may be provided beyond the embedding section of the steel column.

Further, the stiffener material is not limited to being provided in the axial direction of the steel column and the pile, but may be provided in the horizontal direction,
It is also conceivable to provide both in the axial direction and in the horizontal direction.

The structure of the column-pile joint is mainly a one-pillar-one-pile foundation structure in which there is no underground beam connecting the pile heads, and a pillar stands directly from the pile. It is not necessary to limit to the structure, and for example, the present invention can be applied to a case where two or more steel columns stand on one composite pile.

[0028]

[Function] When the axial load of the upper building per pillar is large in a building utilizing the middle and high-rise tracks with the one-pillar one-pile foundation structure, the pile is usually a reinforced concrete pile or other composite pile.

According to the trial design, the dimensions and shape of the column pile joint are as follows, for example, as shown in FIGS. 7 (a) to 7 (c).
(Hereinafter, for convenience of explanation, such a column-pile joint of only the steel column 2 and the composite pile 3 is referred to as an unreinforced column-pile joint).

The ratio (W / H) of the cross section width W and the cross section height H of the composite pile 1 is 3.0 to 6.0.

The section of the steel column 2 has a width W _c of 0.2 to 0.3 (W _c / W) with respect to the pile section width W, and a width H _c of 0 to 0 with respect to the pile section H. 5~0.6 (H _c / H).

It is desirable that the length of the steel column 2 embedded in the composite pile 1 be as shallow as possible as long as the seismic safety of the joint can be ensured.

The following problems arise at the unreinforced column pile joints.

[0034] That is, as shown in FIG. 7 (a), concrete in ShiAki distance H _s smaller column pile joint, FIG. 7
It is expected that the joint concrete 3 is prematurely damaged by punching shear due to the bearing pressure p from the steel column 2 shown in FIG.

Under the above conditions (1) to (3), in order to increase the strength of the column-pile joint, a column-pile joint shown in FIG. The joints are reinforced (hereinafter, the column pile joints when the unreinforced column pile joints are reinforced in this way are referred to as reinforcing column pile joints).

A steel plate having a function of preventing slippage of the entire surface or a part of the outer periphery of the composite pile 1 in a section of Y ≧ L (L: embedded length of steel column) from the top end of the composite pile 1 with the concrete 3 4 (hereinafter, this steel sheet is referred to as an outer peripheral reinforcing steel sheet).

In the section L, the outer peripheral reinforcing steel plate 4 and the steel column 2 are connected by a stiffener 5.

The joint strength of the reinforcing column pile joint is increased by a stress transmission mechanism different from that of the unreinforced column pile joint.

(1) As shown in FIGS. 8 (a) and 8 (b), the bearing pressure p from the steel column 2 is transmitted directly from the steel column 2 to the concrete 3 at the joint, and the force is applied to the back side. Is transmitted to the joint concrete 3 via the stiffener material 5 and the outer peripheral reinforcing steel plate 4. Relates Punching shear fracture strength at this time (in the drawing, c _p represents the fictitious crack line) Punching shear crack surface projected area of greater than unreinforced column pile joint.

(2) As shown in FIGS. 9 (a) and 9 (b), the adhesive force p between the outer peripheral reinforcing steel plate 4 and the joint concrete 3 in the joint.
_a occurs, the adhesion p _a will bear a portion of the bending moment transmitted from the steel columns 2 to the composite pile 1.

(3) The joint concrete 3 is restrained by the outer peripheral reinforcing steel plate 4.

[0042]

FIG. 1 shows an embodiment of the present invention, in which a lower part of a steel column 2 is embedded in a wall-shaped composite pile 1 such as a reinforced concrete pile.
The entire outer periphery of the composite pile 1 is covered with an outer peripheral reinforcing steel plate 4 made of a steel plate with projections such as a striped steel plate.

In this embodiment, as the outer peripheral reinforcing steel plate 4, a steel plate with a projection formed by rolling and having a projection on the inner surface for preventing slippage from the concrete 3 is used, but a shear connector such as a stud dowel is implanted. And so on.

Further, as described in the section of the operation, the outer peripheral reinforcing steel plate 4 and the steel column 2 are connected at four places by the stiffener material 5 to improve the punching shear fracture resistance.

In this embodiment, a steel plate is used as the stiffener material 5, but a stiffened steel or the like may be used.

FIG. 2 shows another embodiment of the present invention, in which the outer peripheral reinforcing steel plate 4 is used as a part of the outer periphery of the composite pile 1, that is, a small punching distance where punching shear fracture is particularly problematic.
This shows a case where the sensor is provided only in the weak axis direction.

The outer peripheral reinforcing steel plate 4 and the steel column 2 arranged on both surfaces in the weak axis direction are connected by a stiffener 5.

FIG. 3 shows, as still another embodiment of the present invention, an example of a two-column, one-pile type in which two steel columns 2 are embedded in one composite pile 1. The concept of reinforcing the joint is the same as in the embodiment of FIGS. 1 and 2 described above.

[0049] Figure 4 is a further embodiment of the present invention, the stiffeners material 5 in 1 Column 1 pile type, steel columns 2
2 shows an example in which the outer peripheral reinforcing steel plate 4 is joined in both orthogonal directions.

FIG. 5 shows, as still another embodiment of the present invention, an example in which the number of stiffener members 5 is changed, that is, a pair of stiffener members 5 are arranged on the center line in the weak axis direction. is there.

FIG. 6 shows, as still another embodiment of the present invention, an example of a four-pillar one-pile type in which four steel columns 2 are embedded in one composite pile 1 .

For the purpose of clarifying the structural performance of the column-pile joint of the present invention, two specimens A and B of the reinforcing column-pile joint having different loading directions shown in FIGS. 10 (a) and 10 (b) were used. Using FIG.
The loading test shown in Fig. 1 was repeated in one direction.

In FIG. 11, reference numeral 11 denotes a specimen,
Is an anchor bolt for fixing the specimen, 13 is 10
A 0tf hydraulic cylinder, 14 is a pin, and 15 is a bearing wall for taking a reaction force. The weight of the load jig is about 500kg
This weight is taken into account when loading.

The specimen A in FIG. 10 (a) was loaded in the strong axis direction, and the specimen B in FIG. 10 (b) was loaded in the weak axis direction.

FIGS. 12 (a) to 12 (d) show the details of the specimen 11 (A, B) having a size of about 1/3 of the actual size.
The horizontal section is 1300 × 40 on the fixing footing part 16.
0 (mm), the height of 900mm height of the wall-shaped composite pile 1,
In the section of Y = 800 mm from the top end of the composite pile 1, the entire outer periphery was covered with a striped steel plate having a thickness t = 4.5 mm having striped protrusions on the inner surface as an outer peripheral reinforcing steel plate 4.

The main reinforcements 17 are arranged at predetermined intervals from the footing 16 to the upper part of the composite pile 1.
A stirrup 18 was arranged around 7.

In the composite pile 1 having such a configuration, the lower end of a column steel frame 2 having a horizontal cross section of 300 × 200 (mm) was embedded. The embedding depth L was 600 mm.

Prior to placing the joint concrete 3, the thickness t = 12 mm, the width 100 mm,
A stiffener 5 made of a steel plate having a length of 600 mm is arranged at four positions, and the stiffener 5 is used to form a column steel frame 2 and an outer peripheral reinforcing steel plate 4.
Was linked.

The mechanical properties of the materials used (steel) are shown in Table 1 below.
As shown in FIG.

[0060]

[Table 1]

Concrete 3 has a design strength of 300 kgf / cm.
^2. Specimen A by compression test with coarse aggregate of 10mm or less
Has a concrete strength of 303 kgf / cm ² , and the specimen B has a concrete strength of 296 kgf / cm ² .

The maximum strength of the specimen A when the horizontal force Q is loaded at a height of 1080 mm from the top of the composite pile 1 is 8
9.75 tf, the maximum proof stress of the specimen B was 35.00 tf.

On the other hand, when the horizontal force Q is applied, the calculated values of the punching shear fracture resistance in the case of the unreinforced column pile joints corresponding to the specimens A and B, which are the specimens of the reinforcement column pile joint, are as follows. The value corresponding to sample A was 13.38 tf, and the value corresponding to sample B was 5.21 tf.

The calculated value is calculated by the virtual concrete crack line c _p shown in FIG. 13 (joint of unreinforced column pile corresponding to specimen A) and FIG. 14 (joint of non-reinforced column pile corresponding to specimen B). Was calculated. 13 and FIG. 14, _n f _l is lower Bearing force, _n f _u upper Bearing force, X _n
Indicates a neutral axis, and the puncture shear rupture strength indicates the area A _p × F _c ^1/2 (F
_c : concrete strength).

The findings obtained from the specimens A and B are described below.

(1) FIG. 15 shows the specimen A, and FIG.
Respectively show the relation between the stigma horizontal force Q and the stigma horizontal deformation amount δ.

From these results, in both the specimen A and the specimen B, the deformation that occurs with each repetition of loading due to the stomatal horizontal force-deformation relation gradually increases and does not converge to a constant value. I understand.

(2) Although not shown, the strain in the circumferential direction of the material was measured by a strain gauge attached to the outer peripheral reinforcing steel plate (a striped steel plate was used in this practical example) of the specimen A and the specimen B when the stigma horizontal force was applied. That is, when the strain distribution due to the hoop tension acting on the outer peripheral reinforcing steel plate was obtained, it was shown that the outer peripheral reinforcing steel plate restrained the concrete in both specimens A and B.

(3) FIG. 17 shows the shear strain (γXY) distribution obtained from the triaxial strain gauge attached to the stiffener material of the specimen B. The left side of FIG. 17 is obtained by the triaxial strain gauge 19 attached to the position a in FIG.

The shear strain of this stiffener 5 (γX
The shear force from Y) is transmitted to the steel column 2 via the adhesive force between the concrete 3 and the outer peripheral reinforcing steel plate 4 (FIG. 18).
reference). A part of the bending moment generated in the joint by the adhesive force is transmitted to the composite pile 1.

(4) FIG. 19 shows the stiffener material 5 of the specimen B.
Force direction (X direction) obtained from the triaxial strain attached to
3 shows the strain distribution.

FIG. 19 shows that the steel columns 1 to the concrete 3
Is applied directly to the concrete 3 from the steel column 2 and the stiffener 5 and the outer peripheral reinforcing steel plate 4.
It can be seen that it is acting on the concrete 3 through the surface (see FIG. 20).

From the above, it can be seen that, by applying the reinforcement in the present invention to the column-pile joint, the joint strength increases with respect to the unreinforced column-pile joint.

[0074]

Effect of the Invention In the steel column pile joint of the present invention, the bearing force from the steel column is directly transmitted to the concrete at the joint, and the concrete is joined to the concrete at the joint via the stiffener material on the back side of the load and the outer peripheral reinforcing steel plate. Since it is transmitted, the punching shear breaking strength in the portion where the clearance distance is short is large.

By providing a slip stopper on the inner surface of the outer peripheral reinforcing steel plate, an adhesive force is generated between the outer peripheral reinforcing steel plate and the joint concrete in the joint, and this adhesive force is a part of the bending moment transmitted from the steel column to the composite pile. To bear.

The joint concrete is restrained by the outer peripheral reinforcing steel plate, thereby increasing the strength of the joint concrete portion.

As described above, it is possible to obtain a joint between a steel column and a pile excellent in mechanical performance for a building utilizing a middle-to-high-rise track.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a plan view, (b) is a front view, and (c) is a side view.

FIG. 2 shows another embodiment of the present invention, in which (a)
Is a plan view, (b) is a front view, and (c) is a side view.

FIGS. 3A and 3B show still another embodiment of the present invention, wherein FIG. 3A is a plan view, FIG. 3B is a front view, and FIG. 3C is a side view.

FIG. 4 shows still another embodiment of the present invention, in which (a) is a plan view, (b) is a front view, and (c) is a side view.

5 shows still another embodiment of the present invention, wherein (a) is a plan view, (b) is a front view, and (c) is a side view. FIG.

6 (a) is a plan view, FIG. 6 (b) is a front view, and FIG. 6 (c) is a side view, showing still another embodiment of the present invention.

FIG. 7 is an explanatory view of punching shear fracture at a joint of an unreinforced column pile as a comparative example, (a) is a plan view,
(b) is a front view, and (c) is a side view.

FIGS. 8A and 8B are explanatory diagrams of an operation related to a supporting force in the present invention, wherein FIG. 8A is a plan view and FIG. 8B is a side view.

FIGS. 9A and 9B are explanatory views of the action relating to the adhesive force in the present invention, wherein FIG. 9A is a plan view and FIG. 9B is a side view.

10 (a) and (b) are schematic diagrams of two specimens of reinforcing column pile joints having different loading directions with respect to the column pile joint of the present invention.

FIG. 11 is a side view showing an outline of the loading device.

FIG. 12 shows the details of the test specimen, where (a) is a side view (right half is a cross-sectional view), (b) is a front view (right half is a cross-sectional view), and (c) is a view of (b). C-C line sectional view, (d) shows D-
It is D sectional drawing.

FIG. 13 shows a hypothetical concrete crack line at a joint of an unreinforced column pile corresponding to the specimen A for numerical calculation of the punching shear fracture strength, (a) is a plan view, and (b) is a plan view.
Is a front view, and (c) is a side view.

FIG. 14 shows a hypothetical concrete crack line at a joint of an unreinforced column pile corresponding to the specimen B for numerical calculation of the punching shear fracture strength, (a) is a plan view, and (b) is a plan view.
Is a front view, and (c) is a side view.

FIG. 15 is a graph showing a relation between a stigma horizontal force Q and a stigma horizontal deformation amount δ of a specimen A.

FIG. 16 is a graph showing a relation between a stigma horizontal force Q and a stigma horizontal deformation amount δ of a specimen B;

FIG. 17 is a view showing a shear strain (γXY) distribution obtained from a triaxial strain gauge attached to a stiffener material of a specimen B.

18A and 18B are diagrams showing a relationship between a stiffener material and an adhesive force, wherein FIG. 18A is a plan view and FIG. 18B is a side view.

FIG. 19 is a diagram showing a strain distribution in a force direction (X direction) obtained from triaxial strain attached to a stiffener material of a specimen B.

FIG. 20 is a side view showing a relationship between a stiffener member and a bearing force.

FIG. 21 shows a one-pillar-one-pile foundation structure for a building utilizing a low-rise track as a conventional example, in which (a) is an overall view of the building, and (b) is a horizontal sectional view of a column-pile joint. (C) is a vertical sectional view of the column pile joint.

FIG. 22 shows a one-pillar / one-pile foundation structure for a building utilizing a middle-to-high-rise track as a conventional example. (C) is a vertical sectional view of the column pile joint.

FIG. 23 is a vertical cross-sectional view of a root-wound column base as a conventional example.

24 (a) and 24 (b) are perspective views showing the state of fracture in a conventional root-winding type column base and a steel pipe-covered root-winding type column base, respectively, and FIG. 24 (c) is an explanatory view showing a cross-sectional shape of the coated steel pipe. FIG.

FIG. 25 is a vertical sectional view showing an embedded column base of a steel pipe concrete column by a double pipe system as a conventional example.

[Explanation of symbols]

1 ... composite pile, 2 ... steel column, 3 ... joint concrete, 4
... peripheral reinforcing steel sheet, 5 ... stiffener material, 11 ... specimen, 1
2 ... anchor bolt, 13 ... hydraulic cylinder, 14 ... pin, 15 ... bearing wall, 16 ... fixing footing part, 17 ...
Main bar, 18 ... band bar, 19 ... strain gauge

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teruki Ishibashi 2-8-8 Hikaricho, Kokubunji-shi, Tokyo 38 Inside the Railway Technical Research Institute (72) Tsuneo Hasuda 2-8-8 Hikaricho, Kokubunji-shi, Tokyo 38 Inside the Railway Technical Research Institute (72) Inventor Shishido is the only 4-5-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries, Ltd. (72) Inventor Keiichi Takada 4-5-33 Kitahama, Chuo-ku, Osaka City No. Sumitomo Metal Industries Co., Ltd. (72) Inventor Akiho Harada 2-6-3 Otemachi, Chiyoda-ku, Tokyo Nippon Steel Corporation (72) Inventor Akira Yoshida 1-1-2, Marunouchi, Chiyoda-ku, Tokyo No. Nippon Kokan Co., Ltd. (56) References JP-A-3-51428 (JP, A) JP-A-3-93923 (JP, A) JP-B-3-64008 (JP, B2) (58) ) Field surveyed (Int. Cl. ⁶ , DB name) E02D 27/00 E02D 27/12

Claims (2)

(57) [Claims] At a joint between a steel column and a pile, in which a lower portion of the steel column is embedded in concrete at the head of the pile, the entire outer periphery of the pile or a part of the outer periphery is covered with an outer peripheral reinforcing steel plate,
A joint between a steel column and a pile, wherein the steel column and the outer peripheral reinforcing steel plate are connected with a stiffener material. 2. The joint between a steel column and a pile according to claim 1, wherein the inner surface of the outer peripheral reinforcing steel plate is provided with a stopper for preventing slippage from concrete.