JPH0742727B2 - Connection structure of columns and beams - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a precast prestressed concrete column or a precast reinforced concrete column for a building (hereinafter referred to as a precast concrete column), a precast prestressed reinforced concrete beam, or a precast prestressed concrete beam (hereinafter referred to as a precast concrete beam). It is related to the joint structure of the joint part (joint).

[0002]

2. Description of the Related Art A prestressed concrete structure has a high yield strength and rigidity, and is extremely rational in terms of suppressing cracking. However, although it has excellent resilience, there is room for improvement in terms of seismic performance because it exhibits hysteresis characteristics that consume less energy than reinforced concrete structures.

FIG. 9 and FIG. 10 show an example of a joint between a precast concrete pillar 1 and a precast concrete beam 2 of a conventional building. 9 is a side view and FIG. 10 is a front view thereof. The pillar 1 and the beam 2 are connected through the joint 15 to the PC steel materials 11 and 12 of the beam and the attached PC steel materials 13 and 1 of the beam end portion.
It was common for them to be attached to one another as crimped structures.

In such a conventional column-beam connection structure,
Since the connection part absorbs less energy against deformation due to an earthquake, the deformation of the frame is larger than that of a normal reinforced concrete structure joint, which causes damage to the joint.

[0005]

SUMMARY OF THE INVENTION The present invention improves the conventional joint structure of precast concrete columns and precast concrete beams, and improves the energy absorption of the joint portion against seismic load by using PC steel and rebar together. It is an object of the present invention to provide a column-beam connection structure that suppresses the amount of deformation during an earthquake and improves the yield strength.

[0006]

The present invention comprises the following technical means. (1) A connection portion having a cross section protruding from the side surface and the bottom surface of the beam is provided at the end of the beam. (2) At the lower end of this connecting portion and the upper part of the beam, connecting reinforcing bars that are connected to the columns are arranged. (3) PC steel materials for connecting the beam and the column are arranged at a position closer to the neutral axis of the beam cross section than these connecting reinforcing bars. This arrangement is, for example, within about ⅔ of the distance from the center of the lower joint reinforcement to the upper surface of the beam, and within about ⅔ of the distance from the center of the upper joint reinforcement to the lower surface of the connecting portion. It is preferable to arrange the PC steel materials for connecting the column and the beam to the respective connection portions so that all the PC steel materials work effectively against the alternating repeated load.

In the present invention, the upper part of the beam includes the beam and the part of the synthetic slab in the synthetic slab in which the beam and the slab are mechanically integrated. The term "joint rebar" refers to a joining bolt or the like in which the joints of the columns and the beams are joined and then grouted to substantially adhere to the concrete, and the insufficient adhesive force is nut-tightened at the ends through a bearing plate. Of course, if the adhesion is sufficient, the bearing plate and nut are not required.

[0008]

In the joint structure of the present invention, the connecting rebars are arranged at the upper and lower portions of the beam of the connecting portion, and the PC steel material for introducing prestress is arranged at a position close to the neutral axis of the cross section. On the other hand, the joint upper and lower rebars bear a large amount of deformation and absorb a large amount of deformation energy. In addition, the PC steel material that exclusively fulfills the crimping function of the joint between the column and the beam is less deformed than the reinforcing bar, and is safe and less damaged during an earthquake.

[0009] In a joint joint in which prestress is introduced by using only PC steel, the area of the loop drawn in the load deformation curve at the time of earthquake is small, and the member having only the reinforcing bar has a large area. That is, the reinforced concrete member has better energy absorption and higher toughness than the prestressed concrete member having only PC steel. FIG. 11 illustrates this, and shows a hysteresis curve when a load is repeatedly applied to a beam-column joint, with the horizontal axis representing the deformation amount δ and the vertical axis representing the load P. When the load acts and the load deformation curve 30 reaches the position of the point 31, when the load is released, the PC member returns as a curve 32, and the reinforced concrete member curves 33.
Return like. In this case, the area surrounded by the curves 30 and 33 is larger than the area surrounded by the curves 30 and 32. That is, the reinforced concrete member absorbs more deformation energy. The present invention is designed to show the intermediate curve 34. In this way rebar and P
When used in combination with C steel, toughness can be increased compared to a member having only PC steel.

[0010]

EXAMPLE FIGS. 1 and 2 show a joint structure of an example of a pillar and a beam according to the present invention. 1 is a view on arrow AA of FIG. 2, and FIG. 2 is FIG.
It is a BB arrow line view of. The pillar 1 and the beam 2 are attached to the left and right and downwardly attached mounting portions 4 provided at the ends of the beam 2 via joints 9. A lower reinforcing bar 5 and PC steel materials 7 and 8 are mounted on the mounting portion 4, and an upper reinforcing bar 6 is formed inside the slab 3. 3 and 4 show beams 2 on both sides of the intermediate pillar 1.
2 is attached, and the reference numerals in the figure are the same as those in FIG.

Next, a test example showing the behavior of the joint structure of the present invention will be described. As shown in FIG. 5, the cantilever 22 was joined to the column 21, and an alternating load 23 was applied to measure the deformation 24. As shown in Fig. 6 (a), the connection of the joint is the lower rebar 5,
The upper reinforcing bars 6 and the PC steel materials 7 and 8 were arranged. The correlation between stress and strain at that time is as shown in FIGS. 6B and 6C.

As a comparative example, the PC steel materials 13 and 14 were arranged as shown in FIG. 7A, and the deformation was measured by applying the alternating load shown in FIG. The correlation between the stress and strain is shown in FIGS.
As shown in. FIG. 8 shows a load deformation curve. In the example shown in FIG. 6, a loop having a good energy absorption is drawn like a curve 25, and in the comparative example shown in FIG. 7, a loop having a low energy absorption is drawn like a curve 26. As described above, according to the present invention, the absorbed energy is large with respect to the deformation of the joint portion of the column and the beam at the time of earthquake, and the joint is safe with little damage.

[0013]

EFFECTS OF THE INVENTION The joint structure of the present invention is highly useful as a seismic-resistant joint structure for construction because it has a large deformation capacity during an earthquake, absorbs energy well, and is tough.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a joint structure of the present invention.

FIG. 2 is a view taken along the line BB of FIG.

FIG. 3 is a side view of the embodiment in the case of an intermediate column.

FIG. 4 is a view taken in the direction of arrows CC in FIG.

FIG. 5 is a side view of the test apparatus.

FIG. 6 is an explanatory diagram of mechanical behavior.

FIG. 7 is an explanatory diagram of mechanical behavior.

FIG. 8 is an explanatory diagram of test results.

FIG. 9 is a side view of a conventional finisher structure.

FIG. 10 is a front view of a conventional finish port structure.

FIG. 11 is an explanatory diagram of a load and a bending curve.

[Explanation of symbols]

1 Pillar 2 Beam 3 Slab 4 Mounting part 5 Lower rebar 6, 7 PC
Steel material 8 Upper rebar 9 Joints 11, 12, 13, 14 PC steel material

Claims (1)

[Claims] 1. A joint portion between a precast concrete column and a precast concrete beam is provided with a joint portion having a cross section protruding from a beam side surface and a bottom surface at an end portion of the beam, and a beam lower portion and a beam upper portion of the joint portion are provided. A column characterized by arranging a connecting rebar for connecting the beam and the column, and arranging a PC steel material at a position closer to the neutral axis of the beam cross section than these connecting rebars and connecting the beam and the column. Beam connection structure.