JP5686414B2 - True pillar - Google Patents

Description

  The present invention relates to a structural pillar. Specifically, it relates to a structural pillar built in a cast-in-place pile by the reverse casting method.

Conventionally, there is a reverse driving method as a method for constructing a building having an underground frame. This reverse driving method is the construction of piles and surrounding mountain retaining walls, and then excavating while building the floor of each layer from the ground surface downward, while simultaneously building the underground frame and the ground frame at the same time It is a technique that can be built. Here, the floor of each layer also serves as a beam for supporting the mountain wall.
This reverse driving method has advantages such as shortening the construction period, securing a working space in a narrow site, securing the safety of the mountain frame, and reducing the influence on the surrounding environment.

  By the way, in the above-mentioned reverse driving method, a structural pillar is built in a pile, and the floors of the ground and underground layers are temporarily supported by the structural pillar. These structural pillars include precast reinforced concrete structures, precast steel reinforced concrete structures, steel structures, etc., but these structural pillars are heavy and require labor and cost to manufacture, transport, and build. There was a problem.

Accordingly, in order to solve this problem, a structural steel column made of filled steel pipe concrete (hereinafter referred to as CFT structural column) has been proposed (see Patent Documents 1 to 3). This CFT structure pillar is constructed by the following procedure. That is, a pile hole is excavated, a rebar cage is inserted into the pile hole, and concrete is placed. Subsequently, a steel pipe is inserted into the pile, and concrete is placed in the steel pipe.
According to this CFT true pillar, since the steel pipe and the concrete inside the steel pipe are integrated, a large compressive strength, bending strength and shear strength can be ensured with a relatively small cross section as compared with the conventional case.

  In the methods shown in Patent Documents 1 and 2, the tip of the CFT true column is closed with a plate material, and the true column with the closed end is built in a pile. When inserting the structural pillar into the pile concrete, the pile concrete exerts a large buoyancy on the tip surface of the structural pillar. Therefore, if the front end of the structural pillar is hollow, the vertical accuracy of the structural pillar is ensured. It becomes difficult. For this reason, before the construction of the structural pillar, only the tip portion of the structural pillar is filled with concrete.

  Moreover, in patent document 3, the front-end | tip of a CFT construction true pillar is open | released, and the construction pillar with this front-end | tip opened is built in a pile. Specifically, after placing concrete on a pile, a built-up column is built, and after the pile concrete has hardened, the built-up column is filled with concrete.

JP-A-4-281915 JP-A-11-264134 Japanese Patent Laid-Open No. 7-119146

  However, in Patent Documents 1 and 2, since the concrete is prefilled in the tip portion of the stem pillar, the weight of the stem pillar increases. In addition, when inserting the structural column into the pile after placing the pile concrete, the resistance of the concrete hitting the tip of the structural column increases, so it is difficult to insert the structural column into the pile head with high accuracy. Therefore, a jig for accurately positioning the true pillar is required. As a result, the problem that construction efficiency fell has arisen. In particular, when the depth of the underground building is increased, this problem becomes prominent because the structural pillar becomes longer.

  Moreover, in patent document 3, when a built-up column is built after pile concrete is laid, the low-strength concrete of the pile head portion flows into the built-up column. There was a possibility that the strength of the could not be secured.

  An object of the present invention is to provide a built-up column capable of ensuring the strength of the joint portion between the built-up column and the pile head while preventing the construction efficiency from decreasing.

  The structural pillar according to claim 1 is a structural pillar that is built into the cast-in-place pile by a reverse casting method, and extends downward and inserted into the cast-in-place pile; An upper portion extending upward from the lower portion, the lower portion is made of a cross H-shaped steel, the upper portion is made of a steel pipe closed at the lower end, and the flange of the lower cross H-shaped steel is constant in the vertical direction It is characterized by a width of.

According to the present invention, the lower part of the structural pillar is made of cross H-shaped steel, the upper part of the structural pillar is made of steel pipe, and after the construction pillar is built in the pile, the concrete is filled in the steel pipe. CFT structure pillar.
Therefore, the strength of the stem column can be ensured while reducing the weight as compared with the conventional case where the entire stem column is made of H-shaped steel. Moreover, the weight at the time of construction of a construction pillar can be achieved compared with the case where the steel pipe with which concrete was previously filled in as a construction pillar is used.

  Moreover, since the lower part inserted in a pile head is an open cross section, when a built-up column is built, a big buoyancy does not act on this built-up column, and the resistance of concrete also becomes small. Therefore, even if it does not use the jig | tool for positioning, a built-up pillar can be built accurately at the time of pile concrete placement, and it can prevent that construction efficiency falls.

  Also, only the upper part of the structural column is made of steel pipe, the lower end of this steel pipe is closed, and the part inserted into the pile head is made of cross H-shaped steel, so that cast-in-place pile concrete enters the steel pipe. In addition, it is possible to secure the strength of the joint portion between the structural pillar and the pile head.

  In addition, the flange of the cross H-shaped steel was made to have a constant width in the vertical direction, and the gap between the flanges of the cross H-shaped steel in the vicinity of the joint portion was largely opened to the outside. Therefore, in addition to making it easier for the concrete to turn inside the cross H-section steel, when performing the pile head treatment, it is possible to secure a sufficient working space inside the cross H-section steel and improve the work efficiency.

  Here, you may position the junction part of a lower part and an upper part in the slab of an underground frame. The slab means a mat slab, a pile head pile cap (foundation slab) of a cast-in-place pile.

Further, in the frame pillar according to claim 1 , a part of the cross H-shaped steel constituting the lower part is extended to the inside of the steel pipe constituting the upper part, and the lower end surface of the steel pipe constituting the upper part Is characterized by being blocked by a plate material.

  According to this invention, in the joint part, while extending a part of cross H-section steel which comprises a lower part to the inside of the steel pipe which comprises an upper part, the lower end surface of this steel pipe was obstruct | occluded with the board | plate material. Therefore, it is possible to resist lateral pressure and buckling by the plate material while reliably joining the cross H-shaped steel and the steel pipe to improve the strength of the joint.

According to a second aspect of the present invention, a stud is welded to the inner wall surface of the steel pipe and the surface of the cross H-shaped steel.

According to this invention, the stud was welded to the inner wall surface of the steel pipe and the surface of the cross H-shaped steel. Therefore, stress can be reliably transmitted between the concrete filled in the steel pipe and the steel pipe, and between the concrete filled in the steel pipe and the cross H-shaped steel.
Moreover, stress can be reliably transmitted between the cross H-section steel and the concrete of the pile.

  According to the present invention, the lower part of the structural pillar is made of cross H-shaped steel, the upper part of the structural pillar is made of steel pipe, and the concrete pipe is filled in the steel pipe after the construction pillar is built in the pile. CFT structure pillar. Therefore, the strength of the stem column can be ensured while reducing the weight as compared with the conventional case where the entire stem column is made of H-shaped steel. Moreover, the weight at the time of construction of a construction pillar can be achieved compared with the case where the steel pipe with which concrete was previously filled in as a construction pillar is used. Moreover, since the lower part inserted in a pile head is an open cross section, when a built-up column is built, a big buoyancy does not act on this built-up column, and the resistance of concrete also becomes small. Therefore, even if it does not use the jig | tool for positioning, a built-up pillar can be built accurately at the time of pile concrete placement, and it can prevent that construction efficiency falls. Also, only the upper part of the structural column is made of steel pipe, the lower end of this steel pipe is closed, and the part inserted into the pile head is made of cross H-shaped steel, so that cast-in-place pile concrete enters the steel pipe. In addition, it is possible to secure the strength of the joint portion between the structural pillar and the pile head. In addition, the flange of the cross H-shaped steel was made to have a constant width in the vertical direction, and the gap between the flanges of the cross H-shaped steel in the vicinity of the joint portion was largely opened to the outside. Therefore, in addition to making it easier for the concrete to turn inside the cross H-section steel, when performing the pile head treatment, it is possible to secure a sufficient working space inside the cross H-section steel and improve the work efficiency.

It is a side view of a construction pillar concerning one embodiment of the present invention. It is an enlarged side view of the junction part of the true pillar which concerns on the said embodiment. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a side view of a structural pillar 1 according to an embodiment of the present invention.
The structural pillar 1 is built in the cast-in-place pile 2 of the reinforced concrete structure of the underground frame by the reverse casting method. This structural pillar 1 has a lower portion 10 that extends in the vertical direction and is inserted into the cast-in-place pile 2, an upper portion 20 that extends upward from the lower portion 10, and a joint provided between the lower portion 10 and the upper portion 20. Unit 30.

  The structural pillar 1 extends from the cast-in-place pile 2 to the ground surface (1FL) level, and the joint 30 is located in the mat slab 3 of the underground frame. In the present embodiment, the foundation is a mat slab type, and the joint portion 30 is positioned in the mat slab 3. However, the present invention is not limited to this. That is, the foundation may be in the form of a foundation beam, and the joint may be positioned in the pile cap.

  Here, for example, the underground frame in which the structural pillar 1 is provided is 5 stories underground, the length of the lower part 10 is 7.5 m, the length of the joint 30 is 3 m, the length of the upper part 20 is 30 m, The thickness of the mat slab 3 is 5 m.

FIG. 2 is an enlarged side view of the joint 30 of the true pillar 1. 3 is a cross-sectional view taken along line AA in FIG. 2, FIG. 4 is a cross-sectional view taken along line BB in FIG. 2, and FIG. 5 is a cross-sectional view taken along line CC in FIG.
The lower part 10 is made of a cross H-section steel 11. Specifically, the cross H-section steel 11 includes a web 12 having a cross-shaped cross section and four flanges 13 provided with end portions of the web 12.
For example, 4 m below the lower portion 10 is a cross H-section steel having a thickness of 30 mm, and 3.5 m above the lower portion 10 is a cross H-section steel having a thickness of 50 mm.

  The upper portion 20 is formed of a rectangular steel pipe 21 having a rectangular frame shape with a closed lower end. For example, the lower 20 m of the upper portion 20 is 1500 mm × 1500 mm × 50 mm × 50 mm, and the upper 10 m of the upper portion 20 is 10 m. It is 1500 mm x 1500 mm x 70 mm x 70 mm. For example, the upper portion 20 bears 40% of the vertical load with the square steel pipe 21 and 60% with the concrete filled in the square steel pipe 21.

In the joint portion 30, only the cross-shaped cross-shaped web 12 of the cross H-section steel 11 constituting the lower portion 10 is extended to the inside of the square steel pipe 21 constituting the upper portion 20. Specifically, the lower end surface of the upper portion 20 is closed by a plate material 22 extending in a substantially horizontal direction, and the web 12 is provided above and below the plate material 22. The plate material 22 is, for example, a plate having a plate thickness of 25 mm.
Further, the flange 13 of the cross H-section steel 11 constituting the lower part 10 is connected to the lower end edge of the square steel pipe 21 constituting the upper part 20. The flange 13 has a constant width in the vertical direction, and a conventional reinforcing plate 16 (shown by a one-dot chain line in FIG. 2) is not provided at the joint portion with the lower end edge of the square steel pipe 21. Thereby, the clearance gap between the flanges 13 of the cross H-section steel 11 directly under the board | plate material 22 is open | released largely outside.

In the joint portion 30, a stud 31 is welded to the inner wall surface of the square steel pipe 21, and a stud 32 is welded to the surface of the web 12 of the cross H-section steel 11 extended to the inside of the square steel pipe 21.
For example, the studs 31 and 32 of the joint portion 30 have a diameter of 22 and are provided with a total of 672 in a total of 48 and 14 steps per step.

  In the lower part 10, a stud 14 is welded to the surface of the web 12 of the cross H-section steel 11. A stud 15 is welded to the outer surface of the flange 13 of the cross H-section steel 11. For example, the studs 14 and 15 of the lower part 10 have a diameter of 22 and a total of 1360 studs are provided over 34 and 34 stages.

  The above-mentioned construction pillar 1 is constructed in the following procedure. That is, a pile hole is excavated, a rebar cage is inserted into the pile hole, and a structural pillar 1 is further inserted. Next, concrete is placed on the pile, and then the concrete is poured into the square steel pipe 21 of the structural column 1 from above to fill it, thereby forming a CFT structural column.

According to this embodiment, there are the following effects.
(1) The lower part 10 of the structural pillar 1 is composed of a cross H-section steel 11, the upper part 20 of the structural pillar 1 is composed of a square steel pipe 21, and the structural pillar 1 is built in the cast-in-place pile 2. Later, concrete is filled into the square steel pipe 21 to form a CFT true pillar.
Therefore, the strength of the stem column can be ensured while reducing the weight as compared with the conventional case where the entire stem column is made of H-shaped steel. Moreover, the weight at the time of construction of the construction pillar 1 can be achieved compared with the case where the steel pipe with which concrete was previously filled in as a construction pillar is used.

  Moreover, since the lower part 10 inserted in the cast-in-place pile 2 pile head is an open cross section, when the built-up column 1 is built, a large buoyancy does not act on the built-up column 1 and the resistance of the concrete is reduced. . Therefore, even if it does not use the jig | tool for positioning, the built-up pillar 1 can be built accurately at the time of pile concrete placement, and it can prevent that construction efficiency falls.

  Further, only the upper portion 20 of the structural pillar 1 is a square steel pipe 21, the lower end of the square steel pipe 21 is closed, and the portion inserted into the pile head is the cross H-section steel 11. The concrete of the cast-in-place pile 2 does not enter, and the strength of the joint portion between the structural pillar 1 and the pile head of the cast-in-place pile 2 can be secured.

  (2) In the joint portion 30, the cross-shaped cross-section portion of the cross H-section steel 11 constituting the lower portion 10 is extended to the inside of the square steel tube 21 constituting the upper portion 20, and the lower end surface of the square steel tube 21 is a plate material 22 blocked. Therefore, the cross H-section steel 11 and the square steel pipe 21 can be reliably joined to improve the strength of the joint portion 30, and the plate material 22 can resist lateral pressure and buckling.

(3) Studs 31 and 32 were welded to the inner wall surface of the square steel pipe 21 and the surface of the cross H-section steel 11 extended to the inside of the square steel pipe 21 at the joint 30. Therefore, stress can be reliably transmitted between the concrete filled in the square steel pipe 21 and the square steel pipe 21, and between the concrete filled in the square steel pipe 21 and the cross H-section steel 11.
Moreover, since the studs 14 and 15 are welded to the surface of the cross H-section steel 11 of the lower part 10, stress can be reliably transmitted between the cross H-section steel 11 and the concrete of the pile.

  (4) The flange 13 of the cross H-section steel 11 was set to have a constant width in the vertical direction, and the gap between the flanges 13 of the cross H-section steel 11 directly below the plate material 22 was opened to the outside. Therefore, the concrete easily turns around inside the cross H-shaped steel 11, and when performing the pile head processing, a sufficient working space can be secured inside the cross H-shaped steel 11 to improve work efficiency.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Structural pillar 2 ... Cast-in-place pile 3 ... Mat slab 10 ... Lower part 11 ... Cross H-section steel 12 ... Web 13 ... Flange 14, 15 ... Stud 20 ... Upper part 21 ... Square steel pipe 22 ... Plate material 30 ... Joint part 31, 32 ... Stud

Claims (2)

It is a structural pillar built in a cast-in-place pile by the back-strike method,
A lower portion extending in the vertical direction and inserted into the cast-in-place pile, and an upper portion extending upward from the lower portion,
The lower part is made of a cross H-section steel, and the upper part is made of a steel pipe whose lower end is closed,
The lower portion of the cross-H-section steel flanges, Ri constant width der vertically,
A part of the cross H-section steel constituting the lower part is extended to the inside of the steel pipe constituting the upper part,
The construction pillar characterized by the lower end surface of the steel pipe which comprises the said upper part being obstruct | occluded with the board | plate material . The inner wall surface and the surface of the cross H-beam of the steel pipe,構真column according to claim 1, characterized in that the stud is welded.

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