JPH0819715B2 - Reinforced concrete column / beam joint reinforcement structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reinforcing structure for a joint portion between columns and beams of a reinforced concrete rigid frame structure.

(Prior Art) Reinforced concrete column-beam joints have generally been conventionally reinforced with stirrups (a) as shown in FIGS. 8 and 9.

In the figure, (A) is a pillar, (B) is a beam, (b) is a pillar main bar,
(C) is a beam main bar, (d) is an orthogonal beam main bar, and (e) is an auxiliary bar.

In recent years, with the development of high-rise reinforced concrete construction, high-strength, large-diameter main reinforcement has come to be used for column and beam members,
The stress level of each part of the pillar, beam and joint panel became extremely high, and the weak point of the frame structure moved to the joint panel rather than the pillar member and the beam member.

As a result, as a reinforcement method for the joints between columns and beams, in addition to arranging a large amount of stirrup, as shown in FIG. 10, a steel plate (f) is wound around the joints between columns and beams (p). Has been proposed.

(Problems to be Solved by the Invention) As shown in FIG. 5, a column-beam joint panel in a rigid frame structure subjected to an earthquake load mainly resists shearing force.

Note that the column N _C is the axial force applied to the column, _U M _C and _D M _C are the bending moments of the upper and lower columns, respectively, _U Q _C and _U Q _D are the shear forces of the upper and lower columns, respectively, and _L M _B and _R M _B are the bending moments of the left and right beams, respectively, and _L Q _B and _R Q _B are the shearing forces of the left and right beams, which act on the column-beam joints. Shear force is horizontal shear force Vertical shear force Becomes

Where j _{B is the} distance between the stress centers of the beam and j _{C is the} distance between the stress centers of the columns. Therefore, in order to ensure seismic resistance, it is desirable to have a frame-column joint panel with high shear strength and high toughness.

However, the shear strength of the column / beam joint panel is hardly increased by the above-mentioned conventional method of arranging a large amount of stirrup on the column / beam joint panel or winding a steel plate.

This is because the shear cracks that occur at the column-beam joints, as shown in FIG. 6, escape to the column ends. That is, as shown in FIG. 7, a reinforcing material that resists the strut force F acting on the column end portion is required.

In the figure, F ₁ is the restraint force due to the column reaction force, F ₂ is the restraint force due to the stirrups, F ₃ is the restraint force due to the beam reaction force, and F ₄ is to prevent shear cracks penetrating from the column-beam joint to the column. It is the necessary binding force.

The present invention has been proposed in view of the above problems of the prior art, and an object thereof is to increase the shear strength and toughness of a reinforced concrete column-beam joint, and as a result, the seismic performance of the structural frame. There is a point to improve.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the reinforced concrete column-beam joint reinforcement structure according to the present invention is surrounded by the upper and lower beam main bars in the column-beam joint of a reinforced concrete frame frame. In addition to winding a reinforcing steel plate around the upper part of the upper beam main bar and the lower side of the lower beam main bar, the reinforcing steel plate is wound over the column-beam joint and the upper column and the lower column, respectively. Has been done.

(Operation) According to the present invention, as described above, the reinforcing steel plate is wound around the portion surrounded by the upper and lower beam main bars in the reinforced concrete rigid frame structure to reinforce the portion, and the upper and lower beams of the upper and lower beam main bars are further strengthened. On the lower side of the main bar, a reinforcing steel plate was wound over a part of the pillar-beam joint and the upper pillar and the lower pillar, so that shear cracks that occur in the pillar-beam joint penetrate into the pillar. It is possible to prevent the above-mentioned pillar / column by supporting the reaction force of the strut mechanism.
Increases shear strength and toughness of beam joints.

(Examples) The present invention will be described below with reference to illustrated examples.

In FIGS. 1 and 2, (A) is a column of a reinforced concrete rigid frame structure, (B) is a beam, and the upper and lower beam main bars (1) and (1) at the joints of the columns (A) and (B) are A reinforcing steel plate (2) is wound around the enclosed portion, and at the upper side of the upper beam main bar (1) and the lower beam main bar (1), the column-beam joint and the upper column are respectively provided. Reinforcing steel plates (2A) and (2B) are wound so as to extend over the lower pillar.

In the figure, (3) is the main pillar muscle, (4) is the stirrups, (5) is the auxiliary muscle,
(1 ') is the main beam of the orthogonal beam.

As described above, in the illustrated embodiment, the column-beam joint is reinforced by the reinforcing steel plate (2) wound around the portion surrounded by the upper and lower beam main bars (1) (1) in the same. ,
The toughness of the frame is superior to that of the conventional reinforcement method using the stirrups.

Further, in the above-described embodiment, not only the reinforcing steel plate (2) but also the reinforcing steel plates (2A) and (2B) are provided, so that restraints for preventing cracks penetrating from the column-beam joint to the column. The force acts so that, as in the conventional reinforcing method in which a steel plate is wound around the beam-column joint, the shear fracture of the beam-column joint does not progress, and the shear crack does not come off in the column portion.

Next, an embodiment of the present invention shown in FIG. 1 and FIG.
Figures 3 and 4 show the results of loading tests assuming seismic loads for the conventional examples shown in Figs. 9 and 10 and Fig. 10, respectively.

Fig. 3 shows the column shear force (Q _C ) -interlayer deformation angle (R _r ) relation envelope, and Fig. 4 shows the column-beam joint shear force (Q _PH ) -shear deformation angle (σ _P ) relation envelope. As is clear from the above experimental results, according to the example of the present invention, the shear fracture of the joint does not proceed as compared with the conventional reinforcing method, and the shear strength is large,
Excellent toughness as a frame. Among the conventional reinforcing methods, the method of reinforcing steel plates is superior in toughness to the method of reinforcing steel strips, but the shear reinforcement of column-beam joint panels has not increased. In addition, in the conventional reinforcement method, the shear fracture of the column-beam joint progresses, and the shear fracture is missing in the column portion.

In the present invention, in the embodiment shown in FIGS. 1 and 2, the stirrups (4) in the portion where the reinforcing steel plate (2) is wound may be omitted.

Further, the reinforcement in the column-beam joint may be made only by the stirrups (4). Further, there is a beam (B) only on one side, and the stirrup (4) in the portion where the reinforcing steel plate (2) is wound is omitted, or
Reinforcement in the column-beam joint may be performed only by the stirrup (4), and the stirrup (4) at the wound portion of the reinforcing steel plates (2), (2A) and (2B) may be omitted and the respective steel plates (2). (2A) and (2B) may be arranged in contact with the column main bar (3). In this case, the reinforcement in the column-beam joint may be only the stirrup (4), or also the case where the beam (B) is only on one side.

(Effect of the invention) As described above, the present invention winds a reinforcing steel plate on a portion surrounded by upper and lower beam main bars in a column / beam joint of a reinforced concrete frame frame, and at the upper side of the upper beam main bar, By winding a reinforcing steel plate over the pillar / beam joint and the upper pillar, and below the lower beam main bar over the pillar / beam joint and the lower pillar, respectively, The shear strength and toughness of the beam joint panel are increased, and as a result, the seismic performance of the structural frame including the column-beam joint is increased.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a reinforced concrete column / beam joint reinforcing structure according to the present invention, FIG. 2 is a cross-sectional plan view thereof, and FIGS. 3 and 4 are columns according to the present invention.・ The results of loading tests assuming the earthquake load of the beam joint reinforcement structure and the conventional column / beam joint reinforcement structure are shown in Fig. 3, the column shear force-interlayer deformation angle relationship envelope, and Fig. 4 is the column. -Beam joint shear force-shows the same shear force deformation angle relationship envelope. FIG. 5 is an explanatory diagram showing the force acting on the column / beam joint panel, FIG. 6 is an explanatory diagram showing an example of the state of destruction of the column / beam joint, and FIG. 7 is supporting the strut mechanism at the column / beam joint. And FIG. 8 and FIG. 9 are longitudinal cross-sectional views showing an example of a conventional joint reinforcing structure of reinforced concrete columns and beams, and FIG. 10 is another cross-sectional plan view. It is a longitudinal cross-sectional view showing an example. (A) …… Column, (B) …… Beam, (1) …… Beam main bar, (2) (2A) (2B) …… Reinforcing steel plate, (3) …… Column main bar, (4) …… Band muscle.

Claims (1)

[Claims] 1. A reinforcing steel plate is wound around a portion surrounded by upper and lower beam main bars in a column-beam joint portion of a reinforced concrete frame structure, and at the upper side of the upper beam main bar and below the lower beam main bar, A reinforced concrete column-beam joint reinforcement structure comprising a reinforcing steel plate wound around the column-beam joint and the upper and lower columns.