JP2001226980A - Embedded fixed column base structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safe and fixed column base structure which can be easily constructed with a high level of safety. SOLUTION: The embedded fixed column base structure is constituted of a foundation beam 1, a steel pipe concrete column 4, and a grout material 6. The foundation beam 1 has a space portion 2 which is formed such that an area of a surface opening 2a is smaller than the maximum area of an internal opening cross sectional area. The steel pipe concrete column 4 is inserted into the space portion 2 through the surface opening 2a. The grout material 6 is injected into a gap between the space portion 2 and the steel pipe concrete column 4.

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 column and a foundation of a steel structure, and connects and fixes a column base (bottom end) called an embedded fixed column base to a foundation made of a reinforced concrete structure. Related to technology.

[0002]

2. Description of the Related Art A general pedestal column without a box is
For example, as shown in JP-A-63-165626,
A steel column or steel tube concrete column is embedded in the foundation beam, and a box made of steel pipe or the like with an inside diameter that is increased by the gap considering the workability of the column diameter in advance is placed on the foundation beam, or in a box shape. By installing a formwork and installing a space for dropping the pillars when casting the foundation beam concrete, dropping the pillars into those boxes and spaces, filling the gap between the pillars and boxes with mortar etc. and solidifying It was fixed.

At this time, as shown in FIG. 6, a stud 15 or the like is attached to an embedded portion of a column 14 to be inserted into a box-opening portion 12 of a foundation beam 11, or a steel tube having a projection as the column 14 is used. ing. The purpose of these studs and protrusions is concrete or mortar (grout part 1).
6), and particularly as a countermeasure against the column 14 coming out when it is pulled upward by the action of an earthquake or the like. In addition, in the figure, 13 has shown the main reinforcement in the foundation beam 11.

[0004]

However, since the resistance to the pull-out force is smaller than that in the case where the compressive force acts, it is necessary to provide a large number of studs and projections. Also, their structure is resistive through the adhesion and shearing of concrete, which is still insufficient from the viewpoint of ultimate safety. For example, if concrete breaks, pillars fall out.

Further, when a stud or the like is mounted, a large amount of clearance must be prepared due to the length of the stud. The costs in terms of installation and construction are also large. On the other hand, if the gap is increased, it becomes more difficult to penetrate and fix the main reinforcement of the foundation beam. In the embedding method, penetration and detour of the main muscles cannot be avoided, but in order to reduce the difficulty as much as possible, it is necessary to minimize the box punching part.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a simpler and more secure structure which can be used in place of a low-yield and low-cost structure such as the above-mentioned studs and ribs.

The embedded fixed column base structure of the present invention passes through a foundation beam having a space having an area of a surface opening smaller than the maximum area of a cross section of an internal opening, and the surface opening inserted into the space. It is made of a pillar and a grout material filled in a gap between the space and the pillar. Further, the cross section of the space is narrowed toward the surface opening. Also,
The shape of the space is a truncated cone or a truncated pyramid.

In addition, a cylindrical body whose upper surface is open and whose side surface is inclined upward and inward is embedded in the foundation beam to form the space. Further, the column is a steel tube column or a steel tube concrete column. Further, a base plate is fixed to the lower surface of the column.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of an embedded fixed column base according to an embodiment of the present invention; 1 is a reinforced concrete foundation beam; Part (or space part), 2a is an upper surface opening of the boxless part, 3 is a main reinforcing bar arranged in the foundation beam 1, 4 is a steel pipe concrete column,
Reference numeral 5 denotes a base plate fixed to the lower surface of the steel pipe concrete column 4, and reference numeral 6 denotes a grout portion made of a grout material which fills a gap between the steel pipe concrete column 4 inserted into the box hollow portion 2 and the box hollow portion 2. In this case, the box blanking portion 2 provided in the foundation beam 1 is formed of a tapered steel pipe having inclined side surfaces, instead of a cylindrical or rectangular tube in the conventional method. This structure uses the compressive resistance, which is the strength of concrete, and is extremely simple, yet has high safety against pull-out force and minimizes the difficulty of penetration and anchorage of reinforcing bars. Limit.

Next, the mechanical mechanism of the above structure is shown in FIG.
This will be described with reference to FIG. When a pulling force acts on the pillar 4, the base plate 5 at the lower end of the pillar 4 attempts to lift the grout portion 6. Since the grout portion 6 is narrowed upward from the shape of the box punching portion 2, the pulling force tends to push up the inclined surface of the box punching portion 2. This force is converted by the wedge effect into a force pushing in a direction perpendicular to the inclined surface of the box punching portion 2. Further, the grout portion (grout mortar / concrete) 6 has a high strength against a compressive force and has a structure that is unlikely to come out to the upper part even if a crack or the like enters (even if a considerable breakage occurs). It has become. Therefore, this structure has high safety against pulling out. Needless to say, the necessary reinforcement is provided on the foundation beam 1, and the foundation beam is not destroyed.

The box removing section 2 is generally constructed by attaching a hollow tube or box to a space formed in the foundation beam 1. The shape of the tube or box is such that the area of the upper surface opening 2a is smaller than the maximum area of the internal cross section, and is basically in the shape of a truncated cone or a truncated pyramid. And they can be applied according to the type of pillar. Also, all side surfaces of the box need not be narrowed toward the upper surface opening 2a,
A shape in which only two or three surfaces are inclined as shown in FIG. 3 can be used. The degree of inclination of the side surface varies depending on the required pulling force (design pulling force of the column), the type and strength of the grout material, the material of the box, and the like, but the area of the upper surface opening 2a is approximately equal to the bottom area. If it is smaller by about 2% or more, it is possible to prevent slipping out.

When such a box having a partly inclined side surface is used for the box punching portion 2, the side pillars and corner pillars can be moved to one side as shown in FIG. Therefore, flexible design becomes possible.

[0013]

According to the structure of the present invention, high safety is secured against the compressive force and the pull-out force. In addition, since there are no studs or protrusions, it is possible to draw a relatively small diameter to a limit distance that can be constructed around the upper part of the box blank portion. For this reason,
The reinforcement of the upper reinforcing bar of the foundation beam is good and the width of the foundation beam can be prevented from becoming unnecessarily wide (B <B in the comparative plan view of FIG. 5).
B '). In addition, since the lower reinforcing bar can be installed below the boxed portion, the lower part of the boxed portion is not particularly problematic. In addition, since studs and protrusions are not required, the cost can be reduced accordingly.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a fixed column base structure according to an embodiment of the present invention.

FIG. 2 is a force action diagram when a pull-out force acts on the structure of FIG. 1;

FIGS. 3A and 3B are a plan view and a side view showing various shapes of a box used for a box punching unit. FIGS.

FIG. 4 is a longitudinal sectional view showing an example of a positional relationship between a box-extracted portion and a pillar.

FIG. 5 is a plan view comparing the arrangement of the upper reinforcing bar of the foundation beam between the method of the present invention and the conventional method.

FIG. 6 is a longitudinal sectional view showing an example of a conventional fixed column base structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Foundation beam 2 Box empty part (or space part) 2a Upper surface opening part 3 Main reinforcement 4 Steel pipe concrete column 5 Base plate 6 Grout part (or grout material).

Claims (6)

[Claims] 1. A foundation beam having a space having a surface opening whose area is smaller than a maximum area of a cross section of an internal opening, a column passing through the surface opening inserted into the space, and the space and An embedded fixed column base structure comprising a grout material filled in a gap between the column and the column. 2. The embedded fixed column base structure according to claim 1, wherein a cross section of said space portion becomes narrower from a bottom portion thereof toward said surface opening. 3. The embedded fixed column base structure according to claim 1, wherein the shape of the space portion is a truncated cone or a truncated pyramid. 4. The space portion according to claim 1, wherein the space portion is formed by embedding a cylindrical body having an open upper surface and an inwardly inclined side surface toward the upper side in the foundation beam. Embedded fixed column base structure. 5. The embedded fixed column base structure according to claim 1, wherein the column is a steel tube column or a steel tube concrete column. 6. An embedded fixed column base structure according to claim 1, wherein a base plate is fixed to a lower surface of said column.