JP2012188872A - Concrete filled circular steel pipe column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concrete filled steel pipe column to be used for a civil engineering building structure.SOLUTION: The concrete filled circular steel pipe column comprises a circular steel pipe column incorporating reinforcements, and a concrete filled therein. A steel pipe to be a panel zone of the steel pipe column when mounted with a beam to construct a column-beam joint part has a ring-shaped holed steel plate inside, joined to the inner periphery of the steel pipe corresponding to the positions of upper and lower beam flanges of the beam, and the steel pipe column has main reinforcements bridged over from a column general part steel pipe joined to the steel pipe to be the panel zone to the steel pipe to be the panel zone and inserted through holes in the annular part of the ring-shaped holed steel plate.

Description

  The present invention relates to a concrete-filled circular steel pipe column used for a civil engineering building structure.

  Concrete filled steel pipe structure filled with concrete inside the steel pipe (CFT structure: also called Abbreviation of Concrete Filled Steel Tube) is characterized by concrete (characteristic of strong compressive force but weak tensile force) and steel pipe (tensile force) It is a structure that is resistant to earthquakes and has fire resistance by eliminating the respective drawbacks by combining it with a characteristic that buckles due to compressive force.

  In concrete filled steel pipe structure 1. The internal structure of the joint between the column and the beam is complicated and expensive. When filling concrete inside the column, it is a drawback that a gap is easily generated between the inner surface of the steel pipe, but due to its excellent performance, various studies have been conducted from various viewpoints such as workability.

  Patent Document 1 relates to a concrete-filled steel pipe with a built-in rebar and a method for joining the same, and a ring plate 53 is fixed to the inside of the vicinity of the opening of the steel pipe 51, and a part of a plurality of through holes provided in the ring plate 53 is placed in the steel pipe 51. The joining method of the concrete filling steel pipe with a built-in reinforcing steel bar which attaches the reinforcing steel bar 55a with the nut 57 and inserts the reinforcing steel 55a of the adjacent steel pipe in another through-hole, and connects steel pipes easily is described. (FIG. 7).

  Patent Document 2 relates to a method for constructing a concrete-filled steel pipe column in which a reinforcing bar 106 is fixed inside a steel pipe 100 via a spacer 102, and an H-shaped steel is provided inside a steel pipe 100 at a column beam joint (also referred to as a panel zone). The upper diaphragm 200 and the lower diaphragm 300 are attached in accordance with the positions of the upper and lower flanges of the beam 108, and the column main reinforcement upper end 109 of the column main reinforcement 107 of the reinforcing bar 106 is inserted into a through hole provided in the lower diaphragm 300 and fixed with a net. In addition, it is described that the column main bar lower end 110 extends from the steel pipe 100 and is inserted into a through hole provided in the upper diaphragm 102a of the lower steel pipe 100a (FIG. 8).

  Patent Document 3 relates to a reinforced steel-reinforced concrete tube column and a concrete-filled double steel tube column in consideration of fire resistance. A circular steel tube 113 and an H-shaped steel beam 108 are joined via a diaphragm 114, and the inside of the circular steel tube 113. Describes a reinforcing steel-reinforced concrete-filled steel pipe column 111 in which the main reinforcement 104 and the hoop reinforcement 112 are arranged so as to satisfy the strength and a predetermined fire resistance time (FIG. 9).

JP 2008-69570 A JP 2003-74120 A JP 2001-279865 A

  By the way, in the case of filled steel pipe columns (including steel pipe columns), a thin steel pipe, that is, a steel pipe with a large diameter-thickness ratio (tube diameter / plate thickness), generally a steel pipe with a diameter-thickness ratio of 66 or more is used. In the column beam joint, the shear strength of the panel zone and the local strength of the joint between the beam and the steel pipe may be insufficient. When the bars are arranged in the column like the steel pipe column described in Patent Document 3, both the column bending strength and the panel shear strength increase, and the panel zone may have insufficient strength against the column strength.

  Even if the reinforcement of the steel pipe column is fixed to the steel pipe column via the diaphragm (Patent Document 2), or the mechanism (Patent Document 1) of fixing the column reinforcement with the plate in the column does not increase the yield strength of the panel zone, A similar phenomenon occurs depending on the diameter-thickness ratio.

  Therefore, the present invention provides a shear strength of the panel zone at the beam-to-column joint when a steel tube having a large diameter-thickness ratio is used in a concrete-filled circular steel tube column (sometimes referred to as a concrete-filled steel tube column), and the connection between the beam and the steel tube. An object of the present invention is to provide a concrete-filled steel pipe column capable of satisfying local proof stress so that each does not become an excessive value.

The object of the present invention can be achieved by the following means.
1. A concrete-filled circular steel pipe column in which concrete is filled in a circular steel pipe column with a built-in rebar, and when a beam is attached to form a column beam joint, the steel pipe that becomes the panel zone with the steel pipe column is internally Corresponding to the positions of the upper and lower beam flanges of the beam, each has a ring-shaped perforated steel plate joined to the inner periphery of the steel pipe, and the steel pipe column is a column general part steel pipe joined to the steel pipe serving as the panel zone A concrete-filled circular steel pipe column having a main reinforcing rod that extends over a steel pipe serving as the panel zone and passes through a hole provided in an annular portion of the ring-shaped perforated steel sheet.
2. The steel pipe column is thicker than the steel pipe of the general part of the column joined to both ends of the steel pipe serving as the panel zone, and the main bar is provided in the annular portion of the ring-shaped perforated steel sheet. 2. The concrete-filled circular steel pipe column according to 1, wherein the hole is fixed after being inserted straight from a steel pipe of a general part of the column joined to the steel pipe to be the panel zone.
3. The steel pipe column has the same thickness as that of the steel pipe serving as the panel zone and the thickness of the steel pipe in the general portion of the column joined to the steel pipe serving as the panel zone, and the main reinforcement is provided in the annular portion of the ring-shaped perforated steel sheet. A hole is linearly inserted from the steel pipe of the column general part joined to the steel pipe to be the panel zone, and then fixed, and between the ring-shaped perforated steel sheets, a pair is provided so as to be parallel to the mounting direction of the beam flange. 2. The concrete-filled circular steel pipe column according to 1, wherein corner reinforcing bars are spanned.

According to the present invention, a concrete-filled circular steel pipe column having the following features is obtained, which is extremely useful in industry.
1. Excellent rigidity and strength at the joint between beam flange and column steel pipe.
2. The column reinforcement is easy to arrange and can transmit the axial force to the steel pipe without fail.
3. It is possible to increase the shear strength of the panel zone.
4). Since the ring-shaped perforated steel sheet does not block the inside of the steel pipe, it has excellent concrete filling properties.

The longitudinal cross-sectional view of the concrete filling circular steel pipe pillar which concerns on one Example of this invention. The AA 'longitudinal cross-sectional view of the concrete filling circular steel pipe pillar shown in FIG. The longitudinal cross-sectional view of the concrete filling circular steel pipe pillar which concerns on one Example of this invention. The AA 'longitudinal cross-sectional view of the concrete filling circular steel pipe pillar shown in FIG. The figure explaining the beam-column joint part (cross frame) used for the Example. FIG. 6 is a plan view of the beam-column joint shown in FIG. 5. Sectional drawing which shows an example of the conventional concrete filling steel pipe column structure. Sectional drawing which shows an example of the conventional concrete filling steel pipe column structure. Sectional drawing which shows an example of the conventional concrete filling steel pipe column structure.

  In the concrete-filled circular steel pipe column, the present invention joins a ring-shaped perforated steel sheet along the inner circumference of the position that becomes the beam flange height inside the steel pipe that becomes the panel zone when the column beam joint portion is configured, The column main reinforcement is inserted and fixed, and depending on the thickness of the steel pipe serving as the panel zone, a reinforcing reinforcement is further used. Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a longitudinal section of a concrete-filled circular steel pipe column according to one embodiment of the present invention, and FIG. 2 shows an AA ′ cross-sectional view of the concrete-filled circular steel pipe column shown in FIG. These figures show a state in which the beams are joined at the beam-column joint. In FIG. 2, the beam of FIG. 1 is shown by the width of the beam flange for easy explanation.

  The illustrated concrete-filled circular steel pipe column has a circular steel pipe column, a reinforcing bar arranged in the column, a ring-shaped perforated steel plate 5 attached in the steel pipe column, and a panel to which the beam 4 is attached. In the zone, a panel steel pipe (thickening) 2 having a thickness greater than that of the steel pipe (column general steel pipe 1) in the other part is arranged. The panel steel pipe (thickening) 2 is a steel pipe whose overall length is longer than the beam back of the beam 4, and preferably the outer periphery of the steel pipe is flat so that it can be connected to the beam flange 4a and the beam web 4b without any gap. The ring-shaped perforated steel plate 5 is joined to the panel portion steel pipe (thickening) 2 by welding or the like.

Inside the panel steel pipe (thickening) 2, ring-shaped perforated steel plates 5 are respectively fixed at positions corresponding to the upper and lower beam flanges 4 a of the beam 4. The ring-shaped perforated steel sheet 5 has a ring shape in the shape of a donut having an opening at the center, and the annular portion sandwiched between the opening and the outer periphery has a plurality of dimensions that allow the column main reinforcement 3 to be inserted among the reinforcing bars in the column. Holes 6 are provided at equal intervals. With the opening,
Since the filling property of the concrete is ensured and also acts as an air vent, the concrete filling around the steel plate 5 is reliably performed.

  The column main reinforcement 3 is stretched linearly in the column general part steel pipe and the panel part steel pipe (thickening) 2, one end of which is welded with the hole 6 inserted in the panel part steel pipe (thickening) 2. It is fixed to the ring-shaped perforated steel plate. In addition to the main column reinforcement, shear reinforcement bars are arranged in the steel pipe column, but they are omitted in the figure.

  According to the present invention, by joining the ring-shaped perforated steel plate 5 to the inside of the panel zone of the beam-column joint (inside the panel portion steel pipe (thickening) 2), the steel plate functions as an inner diaphragm, Improve the rigidity and proof stress of the joint.

  Further, by passing the column main reinforcement 3 through the hole 6, the steel plate also acts as a perforated steel plate gibber, and in the shear direction between the steel plate and the filling concrete 8 in the column with respect to the tensile force of the beam flange 4a. Stress transmission is performed. Therefore, it is possible to secure the joint strength and rigidity on the side of the tension flange, which tends to be insufficient in the concrete-filled steel pipe structure, with less steel material weight than the conventional method.

  Further, by passing the column main reinforcement 3 through the hole 6, it is possible to make the fixing length of the column main reinforcement 3 shorter than that of the conventional structure, and the column main reinforcement 3 fits better. It becomes possible to transmit to the steel pipe (thickening) 2.

  Furthermore, because the steel pipe in the panel zone is thickened to make the panel steel pipe (thickening) 2, the shear strength of the steel pipe or concrete can be increased, and the strength of the panel zone can be made higher than that of the column / beam. Become.

FIG. 3 shows a longitudinal section of a concrete-filled circular steel pipe column according to another embodiment of the present invention, and FIG. 4 shows an AA ′ cross-sectional view of the concrete-filled circular steel pipe column shown in FIG. These drawings show a state in which the beams are joined at the column-beam joint, and FIG. 3 omits the filling concrete for easy explanation.
In FIG. 4, the beam of FIG. 3 is shown by the width of the beam flange for easy explanation.

  In the illustrated concrete-filled circular steel pipe column, the thickness of the steel pipe (panel part steel pipe 2a) in the panel zone to which the beam 4 is attached is set to the same thickness as the steel pipe (column general part steel pipe 1) in other parts. Compared with the case where the thickness is increased, the shear strength of the steel pipe or concrete is reduced. Therefore, between the ring-shaped perforated steel plates 5 attached corresponding to the positions of the upper and lower beam flanges 4a, The diagonal reinforcing bars 7 are spanned and fixed so as to be parallel. The shear strength of steel pipes or concrete is increased, and the proof strength of the panel zone can be made more than the proof strength of columns and beams. The other structure is the same as the concrete-filled circular steel pipe column whose structure has been described with reference to FIG. The diagonal reinforcing bars 7 are preferably fixed in the vicinity of the column main bars 3.

  In the cross frame shown in FIG. 5 (assuming that the tip of the column / beam in the figure is the moment inflection point when the seismic load is applied in the actual structure, the member is designed with the moment of the tip being zero), and the beam is H In the case of −600 × 250 × 12 × 25 SN490 steel, the total plastic bending strength is 1,463 (kN · m), and the shearing force acting on the beam is 395.4 (kN).

The ultimate shear strength of the panel zone and the ultimate tensile strength of the joint between the beam flange and the panel are designed to have a safety factor of 1.4 times against this strength.
(Hereinafter, the steel pipe structure design and construction guideline and the explanation given by the Architectural Institute of Japan will be used for the strength calculation. However, the joint diaphragm strength of the perforated diaphragm (ring-shaped perforated steel sheet) is based on the evaluation formula of the outer diaphragm. To do)
If the panel zone is φ600-16mm steel pipe, the yield stress of the steel pipe is 325N / mm ² , and the filling concrete strength is 60N / mm ² , the ultimate bending moment of the panel zone is 3,622 (kN · m). 579.5 (kN), which satisfies the conditions.

  On the other hand, the perforated built-in diaphragm (ring-shaped perforated steel plate) is 115mm wide and 28mm thick (recommended to be at least one size thicker than the beam flange). By using D19 (SD345), the ultimate tensile strength of the joint between the beam flange and the panel is 2,901 (kN) (including the diaphragm's contribution 2536kN, and the three fixing holes on the front of the flange are evaluated in the same way as the gibber. If the moment of the web is added, the bending strength of the joint is 2,135 (kN · m), and converted to the shearing force of the beam is 577.0 (kN), which also satisfies the conditions (However, a hole with a diameter of 30 mm is regarded as a cross-sectional defect when calculating the diaphragm strength, and the effective width of the diaphragm is calculated as 85 mm).

  Incidentally, if the reinforcing bars are not inserted and fixed in the built-in diaphragm, the width of the diaphragm needs to be 135 mm.

When the diagonal reinforcement (diagonal reinforcement) shown in FIG. 3 and FIG. 4 is applied in the panel zone and designed to have the same yield strength as the panel zone, the yield stress of the φ600-12 mm steel pipe and the steel pipe is 325 N / mm ^2. The diagonal reinforcement D25 and SD345 × 3 (one direction) are required. The weight reduction of the steel pipe from the steel pipe in the panel zone is 33.6 (kg), the weight increase of the diagonal reinforcement is 18.7 (kg), and the steel weight decreases when the reinforcement by the diagonal reinforcement is in the horizontal 1 direction. (The panel zone steel pipe thickened part is not taken into consideration, and the fixed part of the reinforcing bar is not considered).

1 Column general steel pipe 2 Panel steel pipe (thickening)
3 Column main reinforcement 4 Beam 4a Beam flange 4b Beam web 5 Ring-shaped perforated steel plate 6 Hole 7 Diagonal reinforcement 8 Filled concrete 51, 100, 100a Steel pipe 53 Ring plate 55, 55a Reinforcement 57 Nut 102 Spacer 102a, 200 Upper diaphragm 104 Reinforcing bar 106 Reinforcing bar 107 Column main bar 108 H-shaped steel beam 109 Column main bar upper end 110 Column main bar lower end 111 Reinforcement-reinforced concrete-filled steel pipe column 112 Hoop bar 113 Round steel pipe 114 Diaphragm 300 Lower diaphragm

Claims (3)

  A concrete-filled circular steel pipe column in which concrete is filled in a circular steel pipe column with a built-in rebar, and when a beam is attached to form a column beam joint, the steel pipe that becomes the panel zone with the steel pipe column is internally Corresponding to the positions of the upper and lower beam flanges of the beam, each has a ring-shaped perforated steel plate joined to the inner periphery of the steel pipe, and the steel pipe column is a column general part steel pipe joined to the steel pipe serving as the panel zone A concrete-filled circular steel pipe column having a main reinforcing rod that extends over a steel pipe serving as the panel zone and passes through a hole provided in an annular portion of the ring-shaped perforated steel sheet.   The steel pipe column is thicker than the steel pipe of the general part of the column joined to both ends of the steel pipe serving as the panel zone, and the main bar is provided in the annular portion of the ring-shaped perforated steel sheet. 2. The concrete-filled circular steel pipe column according to claim 1, wherein the hole is fixed after being inserted straight from a steel pipe of a general part of the column joined to the steel pipe serving as the panel zone.   The steel pipe column has the same thickness as that of the steel pipe serving as the panel zone and the thickness of the steel pipe in the general portion of the column joined to the steel pipe serving as the panel zone, and the main reinforcement is provided in the annular portion of the ring-shaped perforated steel sheet. A hole is linearly inserted from the steel pipe of the column general part joined to the steel pipe to be the panel zone, and then fixed, and between the ring-shaped perforated steel sheets, a pair is provided so as to be parallel to the mounting direction of the beam flange. 2. The concrete-filled circular steel pipe column according to claim 1, wherein corner reinforcing bars are stretched over.

Images