JP2003313862A - Method for installing cast-in-place steel base column and steel column - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for installing a high strength cast-in-place steel base column and a steel column formable with a simple procedure and capable of performing a high vertical load support by avoiding an inconvenience pro duced by bleeding. <P>SOLUTION: After bleeding water is produced beforehand by leaving the concrete placed at the tip or deeper of a steel column frame 3 built in an excavated hole 2 for a specified time, the steel column frame 3 is fixed. For example, primary concrete 4f and concrete 4r with retarding agent are placed, in order, under a position where the steel column frame 3 is built, and these concretes are left undisturbed for a specified time. Then, before the concrete with the retarding agent is cured, the secondary concrete 4s is placed at the steel column frame 3 portion to fix the frame. Though bleeding occurs also at a fixed portion, the influencing force thereof is small. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast-in-place column and a method of constructing the column.

[0002]

2. Description of the Related Art In a method of building a building upside down, structure columns (steel frames) and structure columns (concrete) are used to support building loads and work loads until the underground structure is completed ( See, for example, Japanese Patent No. 284744).

The design of the root of the true column is carried out mainly by the adhesive force between the steel frame and the concrete, but when designing the true column having a high bearing capacity, the rooting length is lengthened according to the required bearing strength. There is a need. However, since the adhesive force is not exerted over the entire length of the rooting part and is only partially exerted from above the rooting part according to the displacement, even if the rooting length is increased, the expected adhesive force is obtained. It is not possible. In addition, it is not realistic to increase the length of the gantry column in order to secure the rooting length, and it is difficult to construct a high-bearing gantry column by such a method at present. .

On the other hand, if bearing resistance at the tip of the steel frame can be taken into consideration in the design, there is a possibility that it is possible to design a false column having a higher yield strength even with the same insertion length. From such a point of view, a method of fixing a true column in which a convex portion is provided on the outer surface of the flange of the H-shaped steel or a reinforcing rib is provided on the H-shaped steel and fixed in the excavation hole with cement milk is proposed (Japanese Patent Laid-Open No. 2001-2001) 27134
7). In addition, a reinforcing plate that increases the adhesion area of concrete, etc. is installed in the fixing part of the steel material in a direction substantially parallel to the acting direction of the axial force, and a stud dowel etc. is supported in a direction substantially perpendicular to the acting direction of the axial force. A load transfer mechanism has been proposed in which a pressure-reinforcing plate is projected and embedded together with a steel material in a solidified material such as concrete to fix the steel material to the solidified material such as concrete (Patent No. 27).
64648).

[0005] However, in the case of the truss column with a long concrete depth beyond the steel frame tip, the breathing water caused by the hardening of the concrete causes voids and the like in the steel frame tip portion, and therefore the bearing resistance due to the structural change of the truss column. However, in reality, there is a possibility that sufficient bearing resistance will not be exerted even if the improvement of is expected.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and can be formed by a simple procedure and has a high yield strength capable of supporting a high vertical load while avoiding the disadvantage caused by breathing. It proposes a cast-in-place structure pillar and a construction method of the structure pillar.

[0007]

In order to solve the above-mentioned problems, the present invention is such that most breathing water is generated in the early stage of hardening of concrete, and moreover, harmful effects such as voids tend to occur in proportion to the amount of concrete placed. Focusing on the above, it was found that breathing water generated at the tip of the steel frame can be significantly reduced by preliminarily causing breathing in the concrete deeper than the depth of the steel frame by placing an appropriate time after placing the concrete.

That is, in the construction method of the present invention, the primary concrete is poured to a predetermined level below the erected position of the true column built in the excavation hole, and then the predetermined concrete is placed on the concrete. After pouring the concrete containing the retarder to the level, and then allowing it to stand for a certain period of time to generate breathing, pour the secondary concrete on the built-up portion of the structure column above it before the concrete containing the retarder hardens. It was constructed as a construction method for cast-in-place and stand-up columns, which is characterized by installing and fixing the true columns.

According to a second aspect of the present invention, the true column is a true column in which a plurality of bearing reinforcing plates having a T-shaped cross section are circumferentially projected on the outer surface of the fixing portion. It is configured as a structure-supporting pillar and a method of constructing a structure-supporting pillar according to claim 1.

According to the third aspect of the present invention, after placing concrete up to a predetermined level below the planned construction position of the concrete pillar in the excavation hole, the predetermined position of the concrete pillar to be built on the concrete is determined. After pouring the concrete containing the retarder to the level and then allowing it to stand for a predetermined time to cause breathing, before the concrete containing the retarder hardens, the concrete columns are erected in the concrete containing the retarder. It was constructed as a cast-in-place column and a method of constructing the column in which the column is fixed.

According to a fourth aspect of the present invention, the true column is a true column in which a plurality of bearing reinforcing plates having a T-shaped cross section are circumferentially projected on the outer surface of the fixing portion. It is configured as the structure-supporting pillar and the method for constructing the structure-supporting pillar according to claim 3.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, the structure-supporting columns and the method of constructing the structure-supporting columns can be used regardless of whether the structure-supporting columns are pre-built or rear-built.

In the case of a pre-built concrete pillar, for example, FIG.
The following steps are performed as shown in FIG. (a) Excavation of the ground (b) Construction of steel frame (c) Placing of primary concrete (d) Placing of concrete with retarder (e) Generation of breathing water (f) Placing of secondary concrete

First, an existing device, for example, an earth drill method is used to form a drill hole 2 of a predetermined depth in the ground 1 (FIG. 1 (a)), and then a predetermined lower space is formed in the drill hole 2. Open the structure and build the true pillar 3 (Fig. 1 (b)).

Next, below the erected position of the structural column 3 in the excavation hole 2, the primary concrete 4f up to a predetermined level a.
Is placed by a known method such as through the tremie pipe 5 (Fig. 1 (c)), and then a predetermined level b on the primary concrete 4f.
Placing concrete 4r containing retarder until (Fig. 1 (d)
). The retarder used here can be the one that has been conventionally used as an admixture for delaying the setting of cement or concrete, and the amount thereof is appropriately determined in consideration of various factors such as the amount of cast concrete. select.

The predetermined level "a" at which the primary concrete 4f is poured refers to a level at which a space for placing the retarder-containing concrete 4r is provided between the upper part of the predetermined level "a" and the lower end of the false column 3. Further, since the retarder-containing concrete 4r is mainly intended to maintain the quality of the splicing portion between the primary concrete and the secondary concrete, it only needs to have a splicable amount, and compared with the primary concrete 4f. The amount may be small.

Then, in this state, it is left for a predetermined time to generate breathing water in the primary concrete 4f and the retarder-containing concrete 4r, and a part of the breathing water 6 is agitated on the upper surface (FIG. 1 (e)). . The leaving time here may be appropriately selected depending on the amount of the placed concrete, the composition, the hardening time of the concrete 4r containing the retarder, and other factors, and about 4 to 6 hours can be considered as a guide, but naturally it is not limited to this. I can't. In particular, if the retarder-containing concrete hardens, the quality of the jointing part with the secondary concrete 4s will deteriorate, so it is necessary to pour the secondary concrete before hardening, and it is necessary to set the The requirements need to be carefully considered. Primary concrete 3 Primary concrete deeper than the lower end
Most of the breathing water in 4f occurs at this point.

Finally, before the concrete 4r containing the retarder is hardened, the secondary concrete 4s is added to the built-in portion of the structure column 3.
To mount the structure pillar 3 (Fig. 1 (f)). At this time, breathing water is generated also in the secondary concrete 4s, and the generated breathing water 6 rises to the surface of the secondary concrete 4s, but the occurrence of breathing is almost completed in the primary concrete 4f portion below the structure column 3. Therefore, there is little influence of breathing water in the lower part of the structure column, and there is no problem in generating bearing resistance. In addition, by using the retarder-containing concrete 4r, it is possible to prevent deterioration of the workability due to concrete hardening and deterioration of the quality of the joints due to the time elapse after the primary concrete 4f has been poured, and good workability And quality can be secured.

As the structure post 3 used in the present invention, any conventional one can be used, for example,
H-shaped steel, cross-H-shaped steel, and various other forms can be used, but as a more preferable form, it is possible to prevent the inconvenience due to breathing water from accumulating at the steel frame tip part without using the base plate, and Use a true column that can be expected to bear pressure. As such a true column, it is possible to use a structure in which a plurality of bearing support plates 8 having a T-shaped cross section are circumferentially projected on the outer surface of the fixing portion.

As a specific example thereof, as shown in FIG. 2 and FIG. 3, one in which four pressure bearing reinforcing plates 8 having a T-shaped cross section are provided on the outer surface of the flange 7 at the lower end of the cross H-shaped steel so as to project. To be The bearing reinforcement plate 8 can be made of the same material as steel, for example, and can be fixed to steel by an appropriate fixing method such as welding or bonding. The first plate 8a for connecting the steel to one side edge thereof,
The second plate portion 8b in which the other side edge of the first plate portion 8a is connected to the central portion of one surface
It consists of and. In this case, for the purpose of reducing the amount, the first plate portion 8a is a quadrangle whose upper surface is an inclined surface which is inclined outward, and the second plate portion 8b is a trapezoid whose both side surfaces are inclined surfaces which are outwardly inclined. However, the present invention is not limited to this, and may be rectangular, for example.

Further, as the above-described true-structured column, it is possible to use one in which a plurality of plate-shaped pressure-bearing reinforcing plates 8 are provided so as to project along the longitudinal direction on the outer surface of the fixing portion. In this case, the bearing pressure reinforcing plate 8 is not limited to the T-shaped cross section, but may be a simple plate-shaped member. FIG. 4 and FIG. 5 show an example in which a pressure-bearing reinforcing plate 8 in the form of four plates in two steps is provided on the outer surface of the flange 7 at the lower end of the cross H-section steel. In the illustrated example, similarly, in order to reduce the amount of material, each bearing reinforcing plate 8 is formed in the shape of a triangular plate whose upper surface is an inclined surface that descends downward.

6 and 7 show an example in which a plurality of pressure bearing reinforcing plates 8 having a T-shaped cross section are provided on the outer surface of the fixing portion so as to project. In addition, in each of the above-mentioned examples, the cloth H is used as the steel material.
Instead of the shaped steel, it is also possible to use an H-shaped steel having an outer surface to which a similar bearing reinforcing plate is fixed. Naturally, these true pillars are also adopted in the case of a later-constructed building which will be described later.

In the case of the post-construction of the true pillar, for example, as shown in FIG.
The following steps are performed as shown in FIG. (a) Ground excavation (b) Concrete placement (c) Concrete containing retarder (d) Breathing water generation (e) Construction of true columns

First, as in the case of FIG. 1, the excavation hole 2 having a predetermined depth is bored (FIG. 8 (a)), and then a predetermined level is provided in the excavation hole 2 below the planned position of the construction column 3. Concrete 4 up to c is cast, and then concrete 4r containing retarder up to a predetermined level d is cast on the concrete 4 (see FIG. 8).
(c)) Predetermined level c for placing concrete 4
Indicates a level with a space on which the true pillar 3 can be built, as described above.

Then, in this state, it is left for a predetermined time to generate breathing water in the concrete 4 and the retarder-containing concrete 4r (FIG. 8 (d)), and part of the breathing water 6 is raised to the upper surface. The time left here is also shown in Figure 1.
It may be selected in the same manner as in the above case, and the guideline is about 4 to 6 hours, and is not limited to this. Most of the breathing water in concrete 4 is generated at this time, and the breathing water in retarder-containing concrete 4r is also generated at a considerable percentage at this time.

Next, before the concrete 4r containing the retarder is hardened, the concrete columns 3 are built in the concrete 4r containing the retarder to fix the true columns.

In this case, as in the case of the pre-construction method, almost no breathing water has been generated in the concrete 4 below the steel frame tip, so there is almost no inconvenience such as voids at the steel frame tip. . In addition, since the steel frame is inserted after a while, it is expected that the workability will decrease with hardening of the concrete and the adhesive force between the steel frame and the concrete will decrease. Can be secured.

[0029]

As has been described above, the cast-in-place true column and the method of constructing the true column of the present invention are configured as described above, so that the influence of breathing on the true column is eliminated as much as possible. It is possible to form a high-quality rearrangement column, and it is possible to realize a high-bearing rearrangement column that is difficult to achieve by the conventional method. Also,
In the case of designing a true-standing post with the same strength, the rooting length of the true-post can be shortened as compared with the conventional method, and the cost can be reduced.

A cross section T is formed on the outer surface of the fixing portion.
In the case of using a true column with a plurality of letter-shaped bearing support plates protruding in the circumferential direction, the breathing water generated by breathing easily avoids the lower end surface and rises to the bottom of the true column. It is possible to prevent problems such as voids even better.
As a result, it is possible to form a high-strength structure-supporting column and to realize a structure-supporting column having a large bearing resistance and a higher yield strength.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an example of a construction method of the present invention.

FIG. 2 is a side view of an essential part showing an example of a false column used in the present invention.

FIG. 3 is a cross-sectional view of the true column of FIG.

FIG. 4 is a side view of an essential part showing another example of the false column used in the present invention.

5 is a transverse cross-sectional view of the structure injection of FIG. 4. FIG.

FIG. 6 is a side view of a main part showing still another example of a structural injection used in the present invention.

7 is a cross-sectional view of the true column of FIG.

FIG. 8 is an explanatory diagram illustrating another example of the construction method of the present invention.

[Explanation of symbols]

1 ... Ground, 2 ... Drilled hole, 3 ... Structural column, 4 ... Concrete, 4f ... Primary concrete, 4s ... Secondary concrete, 4r
… Concrete with retarder, 5… Tremy tube, 6… Breathing water, 7… Flange, 8… Bearing reinforcement plate, 8a… 1st
Plate part, 8b ... Second plate part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaji Aoki             Chiba Prefecture Inzai City 1-5 Otsuka 1 Stock Association             Takenaka Corporation Technical Research Institute (72) Inventor Riki Takeda             Chiba Prefecture Inzai City 1-5 Otsuka 1 Stock Association             Takenaka Corporation Technical Research Institute F-term (reference) 2D041 AA01 BA04 CB05 DA03 EA04                       EB02                 2D050 AA13 CA04 CB03 EE10 EE18

Claims (4)

[Claims] 1. A primary concrete is poured to a predetermined level below the construction position of a true column built in an excavation hole, and then a concrete containing a retarder is sequentially cast to the predetermined level on the concrete. Then, after leaving for a predetermined time to cause breathing, before the concrete containing the retarder hardens, the secondary concrete is placed in the built-up portion of the structure column above it to fix the structure column. A cast-in-place column and a construction method for the column. 2. The true post of claim 1, wherein the true post is a true post in which a plurality of bearing reinforcing plates having a T-shaped cross section are provided on the outer surface of the fixing portion so as to project in the circumferential direction. Construction method of structure pillar. 3. After pouring concrete to a predetermined level below the planned construction position of the structural column in the excavation hole, concrete with a retarder is poured to a predetermined level at the planned construction position of the structural column on the concrete. Then, after allowing to stand for a predetermined time to cause breathing, before the concrete containing the retardant is hardened, the structure column is installed in the concrete containing the retardant to fix the structure column. Cast-in-place structure pillar and construction method of structure pillar. 4. The false-post column according to claim 3, wherein the false-post column is a false-post column in which a plurality of bearing reinforcing plates having a T-shaped cross section are provided in a protruding manner in the circumferential direction on the outer surface of the fixing portion. Construction method of structure pillar.