JP7198692B2 - Reinforced concrete column beam structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a reinforced concrete column-beam frame structure including reinforced concrete columns and reinforced concrete beams joined to the columns.

Conventionally, in the structural design of reinforced concrete column-beam frames, it is generally designed so that the yield hinge of the beam is formed at the boundary surface between the beam end and the column-beam joint (column-beam joint). there is However, if the difference in bending strength between the column and the beam is small, both the beam main reinforcement and the column main reinforcement will yield within the column-to-beam joint, causing damage to the column-to-beam joint and causing yield failure at the joint, thus achieving the expected seismic performance. may not be possible.

Therefore, as in Patent Documents 1 and 2 below, the strength of the main beam reinforcement on the column-to-beam joint side is made higher than the strength of the beam main reinforcement on the beam center side, so that the yield hinge is generated at the beam end. It is proposed to move from the boundary surface of the column-to-beam joint to the center of the beam (hinge relocation).
Patent Literature 1 discloses a reinforced concrete beam using a reinforcing bar formed to have high strength by quenching the column-to-beam joint side.
Patent Document 2 discloses a reinforced concrete beam in which high-strength reinforcing bars are used as beam main bars on the column-to-beam joint side and normal reinforcing bars are used as beam main bars on the beam center side, and these two beam main bars are joined by mechanical joints. It is shown.

JP 2016-69926 JP-A-01-244040

The present inventors have developed a reinforced concrete column-beam frame structure in which the bending yield hinge occurrence position of the reinforced concrete beam member is moved from the beam side position of the beam-to-column joint to the center of the beam. By using high-strength reinforcing bars for the beam main reinforcement and connecting the high-strength reinforcing bars to the normal-strength reinforcing bars arranged on the center side of the beam with mechanical joints for high-strength reinforcing bars, the bending yield of the beam members is improved. The present invention was achieved by paying attention to the fact that the hinge generation position can be moved toward the center of the beam.

An object of the present invention is to provide a reinforced concrete column-to-beam frame structure in which the bending yield hinge position of the beam can be moved closer to the center of the beam than in the past to reduce damage to the column-to-beam joints during an earthquake. .

A reinforced concrete column-beam frame structure (for example, a column-beam frame structure 1 to be described later) of the first invention includes a reinforced concrete column (for example, a column 10 to be described later) and a reinforced concrete beam joined to the column (for example, a beam 20 to be described later), a first beam main reinforcement (for example, a first beam main reinforcement 60 to be described later) arranged on the center side of the beam, and an end portion of the beam A second beam main reinforcement (for example, a second beam main reinforcement 61 to be described later) arranged on the side is connected by a reinforcing bar joint (for example, a reinforcement joint 62 to be described later), and the second beam main reinforcement is It is characterized by being a large-diameter reinforcing bar or a large-diameter high-strength reinforcing bar as compared with the first beam main reinforcing bar.

According to this invention, the second main beam reinforcement on the side of the beam end and the reinforcing bar joint are made of a large-diameter reinforcement or a large-diameter high-strength reinforcement compared to the first beam main reinforcement on the beam center side. , the bending yield hinge position of the beam moves toward the center of the beam. Therefore, cracks in the vicinity of the bending yield hinge do not reach the column-to-beam joint, preventing yield fracture of the joint and sufficiently ensuring the seismic performance of the column-to-beam joint.

A reinforced concrete column-beam frame structure of a second invention is a column-beam frame structure comprising a reinforced concrete column and a reinforced concrete beam joined to the column, the beam-column frame being arranged on the center side of the beam. A first beam main reinforcing bar and a second beam main reinforcing bar arranged on the end side of the beam are connected at a reinforcing bar joint, and the second beam main reinforcing bar is compared to the first beam main reinforcing bar, It is one of a large-diameter reinforcing bar, a high-strength reinforcing bar, and a large-diameter high-strength reinforcing bar, and the reinforcing bar joint portion is a cylindrical body having a dimension suitable for the diameter of the second beam main bar, and the reinforcing bar joint portion By filling the interior of the reinforcing bar joint with mortar in a state in which the first main beam reinforcing bar and the second main beam reinforcing bar are inserted into, the first main reinforcing bar and the second main reinforcing bar are connected to each other through the reinforcing bar joint. The compressive strength of the mortar that fills the inside of the reinforcing bar joint portion is adapted to the strength of the first beam main reinforcement. The reinforcing bar joint of the present invention is a mortar-filled joint for deformed steel bars.

According to this invention, the second beam main reinforcement arranged on the end side of the beam has a higher strength (for example, USD 590), or large diameter high strength, and the reinforcing bar joint is a cylindrical body with dimensions that match the diameter of the second beam main bar, and the first beam main bar is attached to this reinforcing bar joint and the second beam main reinforcement are inserted, the inside of the reinforcing bar joint is filled with mortar having a compressive strength that matches the strength of the first beam main reinforcing bar, whereby the first beam through the reinforcing bar joint The main reinforcement and the second beam main reinforcement are joined. In the present invention, the second beam main reinforcing bar is a reinforcing bar having a larger diameter, a high strength reinforcing bar, and a high strength reinforcing bar having a larger diameter than the first beam main reinforcing bar. It will be the connecting position of the beam main reinforcement. That is, the second beam bar will not yield, but the first beam bar will yield at the end of the rebar joint. Therefore, the strength of the mortar to be filled inside the reinforcing bar joint may be an inexpensive one that matches the strength of the first beam main reinforcement, and it is necessary to use an expensive high-strength filling mortar that matches the high-strength second beam main reinforcement. no. According to the present invention, even if the beam yields in bending when an earthquake occurs, the bending yield hinge occurrence position of the beam can be moved to the center side of the beam at a lower cost, thereby reducing damage to the column-to-beam joint. Yield fracture can be prevented.

A beam-to-column structure according to a third aspect of the invention is a beam-to-column structure comprising a reinforced concrete column and a reinforced concrete beam joined to the column, wherein the first The beam main reinforcement and the second beam main reinforcement arranged on the end side of the beam are connected at a reinforcing bar joint,
The second beam main reinforcing bar is any one of a large-diameter reinforcing bar, a high-strength reinforcing bar, and a large-diameter high-strength reinforcing bar compared to the first beam main reinforcing bar, and the first beam main reinforcing bar and the second beam main reinforcing bar The beam main rebar has a thread carved on its surface, and the rebar joint is a cylindrical body having a dimension matching the diameter of the second beam main rebar and having a female thread formed therein, and the rebar joint In a state where the first beam main reinforcement and the second beam main reinforcement are screwed together, the reinforcement joint is filled with a grout material suitable for the strength of the first beam main reinforcement into the interior of the reinforcement joint. The first beam main reinforcement and the second beam main reinforcement are joined via a part. The reinforcing bar joint of the present invention is a fitting joint.

According to this invention, the second beam main reinforcing bar is any one of a large-diameter reinforcing bar, a high-strength reinforcing bar, and a large-diameter high-strength reinforcing bar compared to the first beam main reinforcing bar, as in the second invention described above. and screws are engraved on the surfaces of the first beam main reinforcement and the second beam main reinforcement. In addition, for the reinforcing bar joints, fitting type joints having dimensions adapted to the diameter of the second beam main reinforcing bars were used. Therefore, as in the above-described second invention, even if the beam yields in bending when an earthquake occurs, the bending yield hinge occurrence position of the beam can be moved to the center side of the beam at a lower cost, and the beam-to-column joint can be achieved. It is possible to reduce joint damage and prevent joint yield fracture.

ADVANTAGE OF THE INVENTION According to the present invention, the bending yield hinge position of the beam is moved to the center side of the beam compared to the conventional one, and the damage to the column-to-beam joint can be reduced and the column-to-beam joint can be prevented from yielding fracture in the event of an earthquake. Beam-post structure can be provided.

1 is a longitudinal sectional view of a beam-column structure according to an embodiment of the present invention; FIG. FIG. 2 is a cross-sectional view along AA and a cross-sectional view along BB of the column-beam frame 1 of FIG. 1; It is a figure which shows the structure of the test body based on the Example of this invention. FIG. 4 is a side view of a force applicator used in the force test of the specimen shown in FIG. 3; It is a figure which shows the test result of a load test. FIG. 4 is a side view showing a state of the specimen shown in FIG. 3 after completion of a force application test;

The present invention is a column-beam frame structure including reinforced concrete columns and reinforced concrete beams joined to the columns, and is a hinge relocation structure using mechanical joints for beam main bars. In a reinforced concrete beam, a first beam main reinforcing bar arranged on the beam center side and a second beam main reinforcing bar arranged on the beam end side are connected at a reinforcing bar joint. is one of a large-diameter reinforcing bar, a high-strength reinforcing bar, and a large-diameter high-strength reinforcing bar compared to the first beam main reinforcing bar.
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a beam-column structure 1 according to an embodiment of the present invention. 2(a) is a sectional view taken along line AA of the beam-column frame 1 in FIG. 1, and FIG. 2(b) is a sectional view taken along line BB of the beam-column frame 1 in FIG.
The column-beam frame structure 1 includes reinforced concrete columns 10 and reinforced concrete beams 20 joined to column-beam joints 11 of the columns 10 .
On the beam 20, upper beam reinforcements 30A, 30B and lower beam reinforcements 40A, 40B are arranged in two stages, and the beams are wound around the upper beam reinforcements 30A, 30B and the lower beam reinforcements 40A, 40B at predetermined intervals. and a stirrup 50 .
Specifically, four beam top reinforcements 30A are arranged in the first stage (top stage) of the top reinforcement, and two beam top reinforcements 30A are arranged in the second stage (second stage from the top stage) of the top reinforcement. A beam upper end reinforcement 30B is arranged. Four beam bottom reinforcements 40A are arranged on the first stage (lowest stage) of the bottom reinforcement of the beam 20, and two reinforcements are arranged on the second stage of the bottom reinforcement (second stage from the bottom). Beam bottom reinforcement 40B is arranged.

The beam top reinforcements 30A, 30B and the beam bottom reinforcements 40A, 40B are arranged on the first beam main reinforcement 60 arranged on the central portion side of the beam 20 and on the end portion side of the beam 20 (column-to-beam joint 11 side). The second beam main reinforcement 61 is connected to the second beam main reinforcement 61 by a reinforcing bar joint portion 62 .
The first beam main reinforcing bar 60 is a normal strength reinforcing bar (for example, SD490) of deformed reinforcing bar D19 having an outer diameter of 19 mm, but the second beam main reinforcing bar 61 is a high strength reinforcing bar compared to the first beam main reinforcing bar 60. (for example, USD590), or high-strength and large-diameter reinforcing bars (for example, deformed reinforcing bars D22 with an outer diameter of 22 mm at USD590). The large-diameter reinforcing bars of the second beam main bars 61 are up to one size larger than the standard size of the reinforcing bars (for example, D22) compared to the first beam main bars 60 (for example, D19).
The reinforcing bar joint portion 62 is a tubular mortar-filled joint having a dimension adapted to the diameter of the second beam main reinforcing bar 22 . The first beam main reinforcement 60 and the second beam main reinforcement 61 are inserted into both ends of the reinforcing bar joint 62 and fixed by tightening bolts (not shown). In this state, the inside of the reinforcing bar joint 62 is filled with mortar. Thus, the first beam main reinforcement 60 and the second beam main reinforcement 61 are joined via the reinforcing bar joint portion 62 . The reinforcing bar joint part 62 is a mortar filling type joint for deformed bar steel, for example, Super UX (trade name) and Slim Sleeve (trade name) manufactured by Nippon Splice Sleeve Co., Ltd. (trade name), NEW Voltops (trade name), etc. are used.
The mortar that fills the inside of the reinforcing bar joint 62 may have the most general strength. Specifically, the reinforcing bar joint portion 62 is formed by filling the inside of the reinforcing bar joint portion 62 with mortar having a filling type mortar strength (80 N/mm 2 ) for the normal strength beam main reinforcing bar corresponding to the first beam main reinforcing bar 60 . do. In other words, the strength of the mortar with which the reinforcing bar joints are filled is determined according to the strength of the main beam reinforcement on the center side of the beam, not the strength adapted to the strength of the main beam reinforcement on the beam end side.

A moment distribution diagram of the beam 20 during an earthquake is shown in FIG.
Muhr is the ultimate bending strength calculated for the first main beam reinforcement 60, and _Muf is the ultimate bending strength calculated for the second main beam reinforcement _{61. As shown} in FIG. Let p be the end face of the reinforcing bar joint 62 of the beam 20, ie, the position of the side face of the column 10, and let q be the position of the end face of the reinforcing bar joint 62 on the center side of the beam.
As shown in FIG. 1, at position q of beam 20, the bending moment during an earthquake reaches the ultimate bending strength _Muhr calculated at the first beam main reinforcement 60, but at position p of beam 20, bending moment during an earthquake reaches The moment M _uhrf does not reach the ultimate bending strength M _uf calculated at the second beam main reinforcement 61 . Therefore, the beam 20 yields at position q, and this position q is the position where the bending yield hinge occurs.

[Example]
A beam specimen as shown in Table 1 below was produced and subjected to a load test.

That is, as shown in Fig. 3(a), the specimen was a T-shaped beam with a floor slab joined to the top of the beam. The specimen had a beam width of 300 mm, a beam height of 450 mm, a slab width of 300 mm, a slab thickness of 110 mm, an internal length of the test section of 2700 mm, and a shear span ratio (a/D) of 3.0. Also, as shown in FIG. 3(b), the dimension of the end face of the mechanical joint on the side of the center of the beam from the side of the column was set to 300 mm, which is 2/3 of the height of the beam.
In addition, the beam main reinforcement on the beam center side is D19 (SD490) for both the first and second stages, and the beam main reinforcement on the beam end side is D22 (USD590) for the first stage and D19 (USD590) for the second stage. USD590). Also, the bending margin (M _uf /M _uhrf ) was set to 1.20, reflecting the results of the material test.
In addition, as the reinforcing bar joint, Super UX (trade name) or Slim Sleeve (trade name) manufactured by Nippon Splice Sleeve Co., Ltd. is used, and the compressive strength of the mortar filled inside the reinforcing bar joint is 80 N / mm ² . did. In this test, while ensuring sufficient bending margin, the second beam main reinforcement does not yield, and only the first beam main reinforcement yields, so the rebar joint (mechanical joint) is constructed. The interior of the tubular steel body was not filled with the filling mortar for the high-strength beam main reinforcement corresponding to the second beam main reinforcement.
In addition, the shear reinforcing bars were appropriately arranged so that bending yield, not shear failure, occurred when force was applied to the specimen.
In addition, as shown in Fig. 3(a), when constructing the test body, concrete was placed in the lower part of the beam including the bottom reinforcement, and then concrete was placed in the upper part of the beam including the top reinforcement and the floor slab at once. It was constructed.

A force application test was conducted using a force application device as shown in FIG. FIG. 5 shows the test results of the force application test, and shows the relationship between the shear force applied to the specimen by the force application device and the deformation (member angle) of the specimen. FIG. 6 is a side view showing the state of the specimen after the force application test is completed.
From FIG. 6, even if the reinforcement joint portion is not filled with mortar for the high-strength beam main reinforcement corresponding to the second beam main reinforcement, when the specimen yields in bending, the position of the yield hinge moves and the reinforcement joint It can be seen that the position of the end surface of the portion 62 on the side of the center portion of the beam is obtained.

According to this embodiment, there are the following effects.
(1) Compared to the second beam main reinforcement 61 and the reinforcement joint 62 on the end side of the beam 20 with the first beam main reinforcement 60 on the center side of the beam 20, the large-diameter reinforcing bars or large-diameter high-strength reinforcing bars As a result, the bending yield hinge position of the beam 20 moves to the beam central portion side than in the conventional case. Therefore, cracks in the vicinity of the bending yield hinge do not reach the beam-to-column joint 11, thereby preventing yield fracture of the beam-to-column joint and ensuring sufficient seismic performance of the beam-to-column joint 11.

(2) As the reinforcing bar joints 62, a general and inexpensive filling mortar of about 80 N/mm ² suitable for the strength of the first beam main reinforcing bars 60 is used, so construction costs can be reduced. Generally, in a reinforcing bar joint structure in which deformed reinforcing bars having different reinforcing bar diameters or strengths are inserted on both sides of a reinforcing bar joint, the joint strength is determined by the smaller reinforcing bar diameter or the lower reinforcing bar strength. In the present invention, the second beam main reinforcing bar 61 is any one of a large-diameter reinforcing bar, a high-strength reinforcing bar, and a large-diameter high-strength reinforcing bar compared to the first beam main reinforcing bar 60. Therefore, as the reinforcing bar joint 62, A cylindrical body having a dimension suitable for the diameter of the second beam main reinforcement 61 is provided, and a mortar having a compressive strength (for example, 80 N/mm ² ) suitable for the strength of the first beam main reinforcement 60 is provided inside the reinforcing bar joint 62. can satisfy the structural performance required for the beam 20 that moves the yield hinge position.

It should be noted that the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.
In the above-described embodiment, a mortar-filled joint is used as the reinforcing bar joint 62, but the joint is not limited to this, and a fitting joint may be used. In this case, the first beam main reinforcing bar and the second beam main reinforcing bar have threads engraved on their surfaces, and the reinforcing bar joint portion has a strength matching the strength of the second beam main reinforcing bar and has a female thread inside. The reinforcing bar joint is formed by filling the inside of the reinforcing bar joint with a grout material in a state where the first beam main reinforcement and the second beam main reinforcing bar are screwed to both ends of the reinforcing bar joint. The 1st beam main reinforcement and the 2nd beam main reinforcement are joined via. In this fitting-type joint, the second beam main reinforcing bar arranged on the beam end side has a larger diameter reinforcing bar, a higher strength reinforcing bar, and a larger diameter reinforcing bar than the first beam main reinforcing bar arranged on the beam center side. Either high-strength rebar. For the reinforcing bar joint, for example, Ace Joint (trade name) or Free Joint (trade name) manufactured by Tokyo Tekko Co., Ltd., which are dedicated joints for screw tetsucon, are used.

REFERENCE SIGNS LIST 1 Column-beam frame 10 Column 11 Column-beam joint 20 Beam 30A, 30B Beam top reinforcement 40A, 40B Beam bottom reinforcement 50 Stirrup 60 First beam main reinforcement 61 Second beam main reinforcement 62 rebar joint

Claims (2)

A column-beam frame structure comprising reinforced concrete columns and reinforced concrete beams joined to the columns,
A first beam main reinforcing bar arranged on the central portion side of the beam and a second beam main reinforcing bar arranged on the end portion side of the beam are connected at a reinforcing bar joint,
The second beam main bar is a large-diameter reinforcing bar or a large-diameter high-strength reinforcing bar that is one size larger than the first beam main bar according to the standard for deformed reinforcing bars,
The reinforcing bar joint portion is a cylindrical body having a dimension suitable for the diameter of the second beam main bar. By filling the interior of the reinforcing bar joint with mortar in a state where the beam main reinforcing bar is inserted, the first beam main bar and the second beam main bar are joined through the reinforcing bar joint,
The compressive strength of the mortar filled inside the reinforcing bar joint is not the strength that matches the strength of the second beam main reinforcement, but the strength that matches the strength of the first beam main reinforcement ,
In the beam, the second beam main reinforcement does not yield, and only the first beam main reinforcement yields. The first beam main reinforcement and the second beam main reinforcement have screws engraved on their surfaces,
A female thread is formed inside the reinforcing bar joint, and by screwing the first beam main reinforcing bar and the second beam main reinforcing bar to the reinforcing bar joint, the first main reinforcing bar is tightened through the reinforcing bar joint. 2. The reinforced concrete column-beam frame structure according to claim 1, wherein the beam main reinforcement and the second beam main reinforcement are joined.

Images