JP2024175566A - Beam-column joint structure - Google Patents

Abstract

To provide a column-beam joint structure that is easy to construct and reduces shear force that occurs in a material end-reinforced concrete beam of a composite structure beam.SOLUTION: When one direction of beams is for a central steel beam of a material end-reinforced concrete beam 30 and the other direction is for an orthogonal steel beam 20, in a beam intersection portion 40 on a reinforced concrete column 10, where the installed two direction beams 20 and 30 intersect so that the orthogonal steel beam 20 penetrates the beam intersection portion 40, an end of an embedded steel beam 31 of the central steel beam of the material end-reinforced concrete beam 30 extends to the inside of the beam intersection portion 40, and the end of the embedded steel beam 31 and the orthogonal steel beam 20 are composed to be connected via a joint metal in the beam intersection portion 40.SELECTED DRAWING: Figure 1

Description

The present invention relates to a column-beam joint structure, in which one side of the beams that intersect at right angles at the beam intersection on the reinforced concrete column is a steel beam in the center of the end reinforced concrete beam, and the other side is a steel beam.

A structural form that can provide a larger interior space than conventional reinforced concrete beams is known as a steel beam at the center of a reinforced concrete beam at the end (hereinafter referred to simply as a composite beam in this specification) (Patent Document 1). A composite beam is a structural form in which the center of the beam span is a light steel beam, and the end of the beam, which is the joint with the reinforced concrete column (beam-column joint), is made of reinforced concrete. At the end of the composite beam, the steel beam at the center of the beam span is embedded so that it extends to the vicinity of the column of the reinforced concrete beam at the end, and design specifications such as the cross section of the reinforced concrete beam at the end and the required embedded length of the steel beam are determined so that force is transmitted reliably from the steel to the reinforced concrete.

As a structural form for enabling the column side end of a reinforced concrete beam at the end to function efficiently when it is joined to a reinforced concrete column, a configuration has been proposed in which anchor bars are attached by welding or the like to the upper and lower flanges of the end of a steel beam embedded in the reinforced concrete beam at the end, and the end of a steel beam installed in a relative position across the column-beam joint is connected via these anchor bars (Patent Document 2). By having these anchor bars bear part of the bending moment acting on the steel beam, the gradient of the bending moment borne by the reinforced concrete beam at the end becomes gentler, and the shear force generated in the reinforced concrete beam at the end can be reduced.

JP 2009-35928 A JP 2001-173155 A

As shown in Patent Document 2, when anchor bars are welded to the flanges at the ends of steel beams that are incorporated into composite structural beams, a reinforced concrete column may be used as the beam intersection, with one side serving as a composite structural beam and the other side serving as a steel beam, which is perpendicular to the beam. By increasing the strength of these anchor bars, it becomes possible to more rationally design the end reinforced concrete beam. However, because high-strength rebars have a high carbon equivalent, they have poor weldability, with weld cracks occurring at the welded points. For this reason, there are limitations to increasing the strength of rebars.

In the case of a column-beam joint structure 100 in which a stress-transmitting anchor bar 150 is attached to the flange of the steel beam 131 of the composite structural beam 130 shown in each of the figures 4 and 5 as a conventional example, the beam depth of the orthogonal steel beam 120 is designed to be greater than the beam depth of the steel beam 131 of the composite structural beam 130 at the beam intersection 140. For this reason, if the upper flange surfaces of the orthogonal steel beams 120 and 131 are arranged to be aligned in the reinforced concrete column 110, the anchor bar 150 extending from the lower flange of the steel beam 131 of the composite structural beam 130 interferes with the web 120w of the orthogonal steel beam 120, and the anchor bar 150 cannot be arranged as it is. To avoid this problem, for example, as shown in Figure 5, a through hole is drilled in the web 120w of the steel beam 120, and the anchor bar 150 is installed by passing through it. In this case, multiple through holes must be provided in the web 120w of the steel beam 120, which may result in a loss of strength in the steel beam 120.

The object of the present invention is to solve the problems of the conventional technology described above and to provide a beam-column joint structure designed to reduce the shear force generated in the end reinforced concrete beam portion without causing a loss of strength in the steel beam perpendicular to the composite structural beam.

The beam-column joint structure of the present invention is characterized in that in a beam joint structure in which one direction of the beam is a steel beam in the center of the end reinforced concrete beam and the other direction is an orthogonal steel beam, and the beams in the two directions intersect at a beam intersection on a reinforced concrete column, the orthogonal steel beam is erected penetrating the beam intersection, the end of the buried steel beam in the steel beam in the center of the end reinforced concrete beam is extended into the beam intersection, and the end of the buried steel beam and the orthogonal steel beam are joined within the beam intersection via a metal joint.

Another invention is a beam-column joint structure in which one direction of the beam is a steel beam in the center of the end reinforced concrete beam and the other direction is an orthogonal steel beam, and in this beam-column joint structure in which the beams in the two directions intersect at a beam intersection on a reinforced concrete column, the orthogonal steel beam is erected penetrating the beam intersection, and the end of the buried steel beam in the steel beam in the center of the end reinforced concrete beam is joined to the orthogonal steel beam via a metal joint on the surface of the beam intersection.

In the above-mentioned invention, it is preferable that the end of the buried steel frame and the orthogonal steel beam are connected with high-strength bolts via a connecting plate.

It is also preferable that only the web of the buried steel beam extends into the beam intersection.

According to the present invention, a portion of the bending moment at the end of the steel beam of the composite structural beam is transmitted to the steel beam of the composite structural beam on the opposite side of the column-beam joint that continues in the material axis direction via the orthogonal steel beam, thereby reducing the shear force generated in the reinforced concrete beam at the end of the composite structural beam without causing a strength loss in the orthogonal steel beam.

A cross-sectional plan view (a) and a cross-sectional elevation view (b) showing the configuration of one embodiment of the beam-column joint structure of the present invention, in which one side of perpendicular beams is a reinforced concrete beam at the end and a steel beam in the center (composite structure beam), and the other side is a steel beam. 2A is a sectional plan view showing an enlarged configuration of a column-beam joint portion circled in FIG. 1 , and FIG. 2B is a sectional elevation view showing the same. FIG. 4 is an enlarged cross-sectional elevation view showing another embodiment of the column-beam joint structure of the present invention. 1A is a partial plan view and FIG. 1B is a partial elevation view showing an example of a conventional beam-column joint structure in which one side of perpendicular beams is a composite structural beam and the other side is a steel beam. FIG. 1 is a partial cross-sectional elevation view showing a state in which an anchor bar attached to a steel beam of a composite structural beam is installed penetrating an orthogonal steel beam in a conventional example.

Hereinafter, the configuration of the column-beam joint structure of the present invention will be described with reference to the accompanying drawings.
FIG. 1(a) partially shows a plan frame section (Ia-Ia) of an embodiment of a column-beam joint structure 1 of the present invention, in which one direction of the orthogonal beams is a steel beam (composite structural beam) at the center of the end of the reinforced concrete beam, and the other direction is a steel beam. FIG. 1(b) shows an elevation that is a reference for the cross-sectional position of FIG. 1(a). FIGS. 2(a) and 2(b) show enlarged views of the elliptical parts of FIG. 1. The column-beam joint structure 1 is composed of a reinforced concrete column 10, a steel beam 20 erected so as to penetrate the upper part of the reinforced concrete column 10, and a composite structural beam 30 erected in a direction perpendicular to the steel beam 20. At the upper position of the reinforced concrete column 10, a beam intersection 40 where the position where the steel beam 20 penetrates and the longitudinal end of the composite structural beam 30 intersect is constructed with the same plan shape and dimensions as the reinforced concrete column 10. In this specification, the beam intersection 40 is treated as a column-beam joint.

In this embodiment, the reinforced concrete column 10 (hereinafter referred to as column 10) is a column body made of cast-in-place reinforced concrete with a cross section of 1050 mm x 1050 mm. As shown in Figures 2(a) and (b), the column main reinforcement 12 protruding from the upper end of the column body 11 is arranged in a planar position that does not interfere with the steel beam 20 that penetrates the column. The tie bars 13 are arranged outside the installation height of the steel beam 20 and the area where the end of the steel beam 31 is embedded.

As shown in Figures 2(a) and 2(b), in this embodiment, the steel beam 20 is an H-shaped steel (beam depth, beam width: 900 mm x 300 mm), and is erected perpendicular to the composite structural beam 30 so as to penetrate the beam intersection 40 on the column body 11 of the column 10. As shown in Figures 1 and 2, the composite structural beam 30 is composed of a steel beam 31 (beam depth, beam width: 800 mm x 300 mm) at the center in the beam longitudinal direction and end reinforced concrete beams 33 (beam depth, beam width: 1200 mm x 600 mm) at both ends.

The composite structural beam 30 is a composite structure consisting of an H-shaped steel beam 31 that is erected between the reinforced concrete columns 10 perpendicular to the steel beams 20 and forms the center of the beam in the longitudinal direction, and a rectangular cross-section end reinforced concrete beam 33 that is joined to the upper end of the column body 11 (beam intersection 40) so as to cover the beam end of the steel beam 31.

The steel beam 31 is erected in the beam direction across the reinforced concrete column 10, and its longitudinal end 32 is embedded a predetermined length into the beam intersection 40 at the position of the beam intersection 40 on the column body 11, and is bolted to the web 20w of the orthogonal steel beam 20 via a connecting metal fitting described below, and is integrally connected to the steel beam 20 and column 10, forming the column-beam connection structure 1.

The end reinforced concrete beam 33 is constructed as a rectangular cross-section concrete beam that integrally covers the upper end (beam intersection 40) of the column 11, the longitudinal end 32 of the steel beam 31, and the longitudinal end 32 of the other steel beam 31 erected across the column 11. The upper and lower ends of the concrete beam are reinforced with upper end reinforcements 34 and lower end reinforcements 35 that extend in the longitudinal direction of the beam with a predetermined overlap. Anchoring hardware 36 is attached to the ends of the upper end reinforcements 34 and lower end reinforcements 35. Stirrups 37 are arranged at a predetermined interval to encompass the upper end reinforcements 34 and lower end reinforcements 35 of the end reinforced concrete beam 33. The stirrups 37 are also densely arranged near the anchoring hardware 36. The length of the end reinforced concrete beam 33 is preferably 1.5 to 3 times the beam depth of the steel beam 31 embedded in the concrete beam.

2(a) and (b), in the column-beam joint structure 1, the longitudinal end (hereinafter referred to as the end) of the steel beam 31 of the composite structural beam 30 is joined at right angles to the steel beam 20 at the beam intersection 40 on the column 11. In this embodiment, the end of the steel beam 31 is embedded in the column 11 up to the vicinity of the steel beam 20 that penetrates the beam intersection 40. A gusset plate 25 having the same plate thickness as the web 31w of the steel beam 31 is welded to the web 20w of the steel beam 20 facing the end of the web 31w of the steel beam 31. Furthermore, splice plates 26 are attached from both sides between the gusset plate 25 and the web 20w of the steel beam 31, and the steel beam 31 and the steel beam 20 are bolted to each other by eight high-strength bolts 27 via the splice plate 26.

As described above, in the column-beam joint structure 1 of the present invention, a part of the end bending moment of the steel beam 31 of the composite structural beam 30 is transmitted to the steel beam 31 of the composite structural beam 30 on the opposite side of the column-beam joint continuing in the material axis direction, thereby reliably reducing the shear force generated in the end reinforced concrete beam 33. In addition, by increasing or decreasing the number of high-strength bolts 27 used for the joint, the bending moment transmitted to the steel beam 31 of the composite structural beam 30 on the opposite side of the column-beam joint continuing in the beam axis direction can be controlled. Furthermore, when joining the steel beam 31 to the steel beam 20 with a large beam depth, which was a problem in the conventional technology, it is not necessary to penetrate the anchor bar (for example, reference number 150 in FIG. 5) into the web 20w of the steel beam 20, so that the strength loss of the beam can be prevented. In addition, since the anchor bar is not welded to the flange of the steel beam 31, there is no deterioration in the quality of the beam member at the welded point.

Figures 3(a) and (b) show another embodiment of the column-beam joint structure, in which a steel beam 20 penetrating the beam intersection 40 described above is joined to the end of a steel beam 31 of a composite structural beam. In the embodiment of each figure in Figure 2, the end of the steel beam 31 is embedded up to the vicinity of the steel beam 20 located in the beam intersection 40 on the column 11, whereas in this embodiment, the entire steel beam 31 is not embedded in the beam intersection 40, which improves the ease of pouring concrete into the beam intersection 40.

Figure 3(a) shows an example of a structure in which the ends of the upper and lower flanges at the end of the steel beam 31 embedded in the composite structural beam 30 are aligned with the end of the composite structural beam 30, and the web 31w of the steel beam 31 is extended to the vicinity of the steel beam 20 in the beam intersection 40, as shown in the figure. In this example of a structure, since there are no upper or lower flanges of the steel beam 31 in the beam intersection 40, the workability of the bolt joint using the high-strength bolt 27 is improved, and the filling of concrete at the beam intersection 40 can be improved.

Figure 3 (b) shows an example of a structure in which the end of the steel beam 31 embedded in the composite structural beam 30 is aligned with the end of the composite structural beam 30, and the gusset plate 25 attached to the steel beam 20 penetrating the beam intersection 40 is designed to be large and extend close to the outer surface of the beam intersection 40, and the gusset plate 25 and the web 31w of the steel beam 31 are bolted to the column-beam joint surface position with a high-strength bolt 27. In this example of a structure, the joining work between the steel beam 31 of the composite structural beam and the steel beam 20 at the beam intersection 40 can be performed at the surface position of the beam intersection 40, making it easier to join the steel beams 20, 31.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. In other words, embodiments obtained by combining technical means that are appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

Reference Signs List 1: Beam-column joint structure 10: Reinforced concrete column 11: Column body 20, 31: Steel beam 22: End reinforced concrete beam 25: Gusset plate 26: Splice plate 27: High-strength bolt 30: Composite structural beam 33: Reinforced concrete beam 40: Beam intersection

Claims (4)

In a column-beam joint structure in which one direction of the beam is a steel beam in the center of the end of a reinforced concrete beam and the other direction is an orthogonal steel beam, and the beams in the two directions intersect at the beam intersection on the reinforced concrete column,
The orthogonal steel beam is erected through the beam intersection portion,
The end of the embedded steel beam in the central part of the reinforced concrete beam is extended into the beam intersection,
The end of the buried steel beam and the orthogonal steel beam are joined via a joint metal in the beam intersection portion.
A column-beam joint structure characterized by: In a column-beam joint structure in which one direction of the beam is a steel beam in the center of the end of a reinforced concrete beam and the other direction is an orthogonal steel beam, and the beams in the two directions intersect at the beam intersection on the reinforced concrete column,
The orthogonal steel beam is erected through the beam intersection portion,
The end of the embedded steel beam of the central steel beam of the end reinforced concrete beam and the orthogonal steel beam are joined via a joint metal on the surface of the beam intersection.
A column-beam joint structure characterized by: The column-beam joint structure according to claim 1 or 2, in which the end of the buried steel frame and the orthogonal steel beam are joined with high-strength bolts via a joining plate. The column-beam joint structure according to claim 1, in which only the web of the buried steel beam extends into the beam intersection.

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