JPS63165626A - Structure of reinforcement column base - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention aims to increase the yield strength of the steel column base of buildings, etc. in order to enable the total plastic moment of the column to be transmitted to the foundation beam. The present invention relates to an improved structure of a box-cut type embedded column base.

[Conventional technology]

Conventionally, the structure of a box-cut embedded column base is as shown in FIG. 6, in which a box-shaped hollow part 1 is provided in the foundation beam using a formwork such as a box-cut part 11 made of paper or the like, and a shear connector is attached here. A steel column 3 was erected with studs 2 installed, and then filled with post-cast concrete. A common method for reinforcing such column bases is to arrange hoop-shaped reinforcing bars 4 around or inside a box-shaped, ie, box-cut portion 11.

The load-bearing mechanism of this column base is the structure of the steel column 3 as shown in Figure 7.
A part of the moment M due to the force Q acting on the steel column 3 is shared by the stud 2 installed in the steel column 3.
In this way, the stability of the column base can be made greater than that of the exposed column base by providing appropriate reinforcement. Furthermore, since the steel column 3 is erected after the foundation beam is completed, the construction period can be shorter than that of an embedded column base using a general construction method.

[Problem that the invention seeks to solve]

The conventional box-cut type embedded column base configured as above is
This improves the degree of fixation and shortens the construction period, but since the box-cut holes must be made larger, the mounting plate for the construction method becomes larger, the foundation beam width must be wider, and the anchor bolts for the construction method are It was difficult to set because it was at the bottom.

Furthermore, since there is a joint in the concrete of the foundation beam, the strength, fixity, horizontal rigidity, etc. are lower than with conventional one-piece concrete, and there is also concern about the filling ability of post-cast concrete, so the joint is not used. It had to be reinforced, and the reinforced area was large. Furthermore, as shown in Figure 7, the conventional load-bearing mechanism responds to the moment M acting on the steel column.
This resistance is achieved by transmitting the shear force of the shear connector by installing a stud in the steel column, but this stud does not contribute to increasing rigidity, and the actual load-bearing mechanism is the bearing capacity of the steel column and concrete. I'm resisting. Therefore, especially in the case of corner columns, we expect the concrete on the outside of the column to improve the rigidity, so we increase the end clearance length of this part.
For example, there was a problem in that it had to be more than twice the length of the pillar D, and that this part also needed to be reinforced.

This invention was made in order to solve the problems of the conventional construction method as described above, and it is possible to reduce the width of the foundation beam, and to increase the strength of the column base without particularly reinforcing the concrete joints. The aim is to improve fixation, horizontal rigidity, etc., and to significantly improve workability.

[Means for solving problems]

In the steel column base structure according to the present invention, a square steel pipe or the like is used as the column cutting form, and the foundation beam is designed to directly transmit the total plastic moment of the steel column to the foundation beam via the square frame steel pipe or the like. The main reinforcement or anchor reinforcement and the above-mentioned formwork steel pipe are connected by welding or the like.

[For production]

In the steel column base structure configured as described above, the column base is surrounded by square steel pipes welded to the main reinforcement of the foundation beam, so concrete is placed inside the box-cutting form made of the square steel pipes. When filled, the moment of the steel column can be transferred to the foundation beam only through the compressive force of the concrete.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. 1st
The figures show a first embodiment of the present invention, and are a plan view and a side sectional view showing a column base structure using an H-shaped beam as a steel column. Fig. 2 is an explanatory diagram showing the load-bearing mechanism of the present invention, Fig. 3 is a plan view of the second embodiment using square steel pipes as the steel column, and Fig. 4 is a plan view of the second embodiment in which the steel column is embedded deep. Fig. 5 is a plan view showing a fourth embodiment in which a high-strength grout mortar is used instead of the filling concrete to reduce the box-opening space and therefore the end gap length. .

In FIG. 1 showing the first embodiment, 1 is post-cast concrete to be filled into the boxed space, 3 is a steel column made of H-shaped steel, 5 is an anchor mounting plate (erecting plate), and 3 is a steel column 3. Temporarily fastened when building. Numeral 6 is an anchor for construction, and fixes the anchor mounting plate 5 to the foundation beam. Reference numeral 7 indicates a square steel pipe used as a formwork for punching out boxes, 8 indicates main reinforcing bars arranged within the foundation beam, and 9 indicates anchor reinforcing bars arranged within the foundation beam.

Next, a construction method based on the above configuration will be explained.

Main reinforcement 8 and anchor reinforcement 9 are installed in the formwork to form the foundation beam.
In addition to arranging tie reinforcements, a box-cut formwork 7 made of a square steel pipe is placed at the position where the column base will be embedded, and the main reinforcement 8 is connected to this by welding, or the outer circumference of the square steel pipe 7 is surrounded. The reinforcement was placed in a U-shape as shown in the figure, and concrete was poured to complete the foundation beam.

Next, after the foundation beam is completed, the steel column 3 is temporarily fixed to the anchor mounting plate (construction plate) 5 using the erection anchor 6, and after the erection, the foundation beam concrete is placed in the space of the formwork steel pipe 7. High-strength post-cast concrete will also be poured. In this embodiment, the steel column 3 is embedded shallowly, and its reinforcement is performed by anchors 6 via anchor mounting plates 5. However, the presence or absence of this anchor 6 or its cross-sectional area
Determined by structural calculations required for column moment retention joints.

In this way, a load-bearing mechanism as shown in Figure 2 will be created, and the moment M acting on the steel column 3 will be transmitted to the foundation beam only by compressive stress, so it is expected that the bearing capacity of the concrete in the open end will be high. Therefore, sufficient strength can be obtained even if the end clearance length is small, for example, the end clearance length is 0.5D (previously 2D or more) for the column depth D, and the steel frame near the site boundary line Even when constructing Pillar 3, the ease of implementation is greatly improved.

In FIG. 3 showing the second embodiment, a square steel pipe is used as the steel column 3, and it is constructed in the same manner as the first embodiment shown in FIG. 1, but in this case, the steel column 3 is Hollow pipes or steel pipes can be used as concrete pillars, and in the case of hollow pipes, the ends may be closed with steel plates or left open.
The same effects as in the embodiment can be obtained. In addition, in the case of hollow pipes, it is more effective to make a hole next to the column 3 into which concrete can be poured, and then fill the steel column 3 with highly fluidized concrete when pouring the post-cast concrete 1. Become.

Further, FIG. 4 showing the third embodiment shows an example in which the embedding depth is deep, and in this case, the upper and lower end reinforcements of the main reinforcement 8 of the foundation beam are connected to the formwork steel pipe 7 by welding. , or arrange reinforcement in a U-shape.

Furthermore, as a fourth embodiment, if high-strength grout mortar 10 is used instead of post-cast concrete, the square steel pipe 7 for the box-cutting form can be made smaller, as shown in FIG. In this case, if the aggregate of the high-strength grout moldal (or highly fluidized concrete) 10 is made with a small diameter, the clearance between the steel column 3 and the formwork steel pipe 1 can be set to about 10 mm. The end clearance can be made smaller, and the haunch, which is a section-increasing part conventionally provided at the corner of a foundation beam, is no longer necessary.

In any of the embodiments described above, the load-bearing mechanism according to the present invention does not expect the bearing capacity of the concrete in the open end portion as shown in FIG. Reinforcement is not required, and the concrete joints do not need to be reinforced by other means (furthermore, it is possible to reduce or eliminate tie bars for steel column enclosures. Also, the anchor bolts 6 for erection can be used for formwork Since it is set in the steel pipe 7, its dimensional accuracy is high, and since it protrudes above the top surface of the foundation beam, the steel frame column 3 can be easily erected.

〔Effect of the invention〕

As described above, according to this invention, the column base is surrounded by a square steel pipe as a box-cut formwork that is welded to the main reinforcement of the foundation beam, so it is expected that the bearing capacity of the concrete in the open end will be high. This is not necessary, and the strength, fixation, and rigidity can be greatly improved compared to exposed column bases by reducing the length of the end gap and without reinforcing this part. In addition, since the box-cut holes are smaller, the width of the foundation beam can be narrowed, corbels are no longer required, and the reinforcing structure can be simplified, resulting in the effect of shortening the construction period and reducing costs.

[Brief explanation of the drawing]

FIG. 1 fa) is a plan view showing a first embodiment of the present invention;
(bl is a side sectional view thereof, FIG. 2 is an explanatory diagram showing the load-bearing mechanism of the present invention, FIG. 3 is a plan view showing the second embodiment,
The figure is a side sectional view showing the third embodiment, FIG. 5 is a plan view showing the fourth embodiment, and FIG. 6(a) is a plan view showing the conventional example.
(bl is a side sectional view thereof, and Fig. 7 is an explanatory diagram showing a conventional load-bearing mechanism. In the figure, 3 is a steel column, 5 is an anchor mounting plate, 6 is an anchor for erection, 7 is a formwork steel pipe, 8 is the main reinforcement of the foundation beam, and 9 is the anchor reinforcement. Applicant: Nippon Steel Tube Co., Ltd.

Claims (1)

[Claims] In box-cut type embedded column bases, a square frame steel pipe or the like is used as the box-cut frame, and the main reinforcing bars or anchors of the foundation beam are connected so as to directly transmit the total plastic moment of the steel column to the foundation beam via the square frame steel pipe or the like. A steel column base structure characterized in that the reinforcement and the formwork steel pipe are connected by welding or the like.