JP3964412B2 - Highly deformable concrete member - Google Patents

Description

  The present invention relates to a high deformation performance concrete member, and more particularly to a high deformation performance concrete member having a large cross section such as a concrete pier.

  Conventionally, a concrete member has an axial reinforcing bar arranged in a longitudinal direction of the member along each surface thereof, and a reinforcing bar structure in which band reinforcing bars are arranged at predetermined intervals in the axial direction so as to surround the axial reinforcing bar from the outside. It has become. In this case, in order to guarantee the deformation performance at the time of a large earthquake, the arrangement of the band reinforcement was dense.

  However, when the amount of the reinforcing bars surrounding the axial reinforcing bars increases, a great deal of labor is required for assembling the reinforcing bars and placing the concrete. In addition, since the interval between the strip reinforcing bars is short, the axial reinforcing bars are likely to be broken by a small number of repeated loads. In addition, after the yielding of the axial rebar due to the effect of alternating repeated loads during an earthquake, the stretched part of the axial rebar begins to squeeze when it receives a compressive force, the surrounding rebar is pulled, and the rebar is yielded. Since the concrete is not restrained, the deformation performance after the covering concrete is peeled off sharply decreases.

Therefore, as a method of arranging the reinforcing material for the concrete member, a strip reinforcing bar or steel pipe is placed inside the axial rebar for the section (root section) that becomes a plastic hinge at the time of an earthquake so as to be substantially inscribed in the region surrounded by the axial rebar. An arrangement method has been proposed (see, for example, Patent Documents 1 and 2). Accordingly, the concrete inside the axial rebar can be constrained without densely arranging the belt reinforcing bars, and the deformation performance can be improved.
JP 2000-179090 A JP 2003-41657 A

  However, in the conventional method, when the cross section of the concrete member becomes large, it is necessary to increase (increase) the reinforcing material inscribed in accordance with the cross section or to arrange a large number of reinforcing materials inscribed. If the reinforcing material is made larger (longer), the force to constrain the internal concrete will decrease, and if a large number of reinforcing materials are arranged, the reinforcing material will be placed even in areas where there is no need to constrain (near the center of the cross section). Therefore, there is a problem that the amount of the reinforcing material is increased and the workability is deteriorated.

  An object of the present invention is to ensure the deformation performance in the event of a large earthquake even when the cross section of the concrete member is large, and to efficiently arrange the reinforcing material to improve the workability.

In order to solve the above problems, a highly deformable concrete member according to the first aspect of the present invention is a concrete member (concrete pier 1 having an arbitrary cross-sectional shape in which axial reinforcing bars 20 are arranged, as shown in FIG. In the plastic hinge section 1a formed by the external force acting on the concrete member, the first restraining reinforcing bar 2 that partially restrains the compression side of the internal concrete 1b inside the axial reinforcing bar 20 Are arranged along the compression edge,
The first restraining rebar 2 is formed in a semicircular arc shape, and is a rebar in which bent portions 2a for fixing to the internal concrete 1b are formed at both ends,
The semicircular arc-shaped first restraining rebar 2 is arranged with the arc side facing the compression edge and symmetrically arranged with respect to the central portion in the thickness direction of the concrete member ,
Between the bent portions 2a, 2a at both ends of the first restrained reinforcing bar 2, a second restrained reinforcing bar 3 is disposed which is formed in a straight line and has bent portions 3a formed at both ends. The bent portion 2a of the first restraining reinforcing bar 2 and the bent portion 3a of the second restricting reinforcing bar overlap with each other .

  As described above, a plurality of first restraining reinforcing bars 2 that partially restrain the compression side of the internal concrete 1b are arranged along the compression edge inside the axial reinforcing bar 20, and thereby each first restraining bar 2 is arranged. The compression side of the internal concrete 1b in the part where the reinforcing bar 2 is located can be restrained, and the entire internal concrete 1b can be restrained efficiently. Therefore, the amount of the reinforcing material can be reduced as compared with the conventional case, and the workability of the arrangement work can be improved.

The high deformation performance concrete member of the invention according to claim 2 is a concrete member (concrete pier 1) having an arbitrary cross-sectional shape in which axial reinforcing bars 20 are arranged as shown in FIG. 2 , for example. In the plastic hinge section 1a formed by the external force acting on the inside, a plurality of first restraining reinforcing bars 2 that partially restrain the compression side of the internal concrete 1b inside the axial reinforcing bar 20 are arranged along the compression edge. Has been
The first restraining rebar 2 is formed in a semicircular arc shape, and is a rebar in which bent portions 2a for fixing to the internal concrete 1b are formed at both ends,
The semicircular arc-shaped first restraining rebar 2 is arranged with the arc side facing the compression edge and symmetrically arranged with respect to the central portion in the thickness direction of the concrete member,
Between the opposing bent portions 2a and 2a of the first constrained reinforcing bars 2 and 2 that are arranged symmetrically, there are arranged shear reinforcing bars 4 with bent portions 4a formed at both ends. The bent portion 2a of the first restraining reinforcing bar 2 and the bent portion 4a of the shear reinforcing reinforcing bar 4 are overlapped.

  In addition, it is preferable to make the plastic hinge area 1a into a range from about 0.5 to 2.0 times the cross-sectional height from the end of the concrete member considered to be formed by the plastic hinge during an earthquake.

According to the first and second aspects of the present invention, in the concrete member having an arbitrary cross-sectional shape in which the axial rebar is arranged, the axial rebar is provided in the plastic hinge section formed by the external force acting on the concrete member. Multiple primary restraining bars that partially restrain the compression side of the inner concrete along the compression edge on the inside, so that the amount of reinforcement is reduced compared to the previous one while ensuring deformation performance during a large earthquake It is possible to improve the workability of the placement work.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
The high deformation performance concrete member in the first and second embodiments described below is applied to the concrete bridge pier 1 having a rectangular cross section as a concrete member. As shown in FIGS. 1 and 2 , the concrete pier 1 is arranged in a state in which axial rebars 20 are arranged in parallel at a position a predetermined distance from the outer peripheral surface of the cross section. When an external force is applied to the concrete pier 1, it is assumed that a large bending moment is applied to the root section of the concrete pier 1 to form a plastic hinge. In the sections other than the plastic hinge section 1a, the axial reinforcing bars 20 and the strip reinforcing bars 21 for restraining the concrete are arranged at predetermined intervals in the axial direction on the outside of the axial reinforcing bars 20 as in the prior art. An intermediate rebar (not shown) is arranged.

[First Embodiment]
In the embodiment shown in FIG. 1, the plastic hinge section 1 a of the concrete bridge pier 1 is placed inside the axial reinforcing bar 20, for example, in a section ranging from the base end to about 0.5 to 2.0 times the cross-sectional height. A plurality of first restraining reinforcing bars 2 (reinforcing materials) that partially restrain the compression side of the internal concrete 1b are arranged along the compression edge.

  The first restraining reinforcing bar 2 is a reinforcing bar formed in a substantially semicircular arc shape, and bent portions 2a (hooks) for fixing to the internal concrete are formed at both ends.

  Since such a first restraining reinforcing bar 2 is arranged inside the axial reinforcing bar 20 on the compression side of the internal concrete 1b, the compression side is partially restricted. And since the 1st restraint reinforcement 2 is arranged in multiple numbers along the compression edge, the whole internal concrete 1b can be restrained efficiently. Therefore, even if the cover concrete is peeled off and the axial steel material swells outward, the first restraining rebar 2 is restrained so as not to escape the compression side of the internal concrete 1b, so that the deformation performance does not deteriorate. .

Also, in order to increase the restraining force against the internal concrete 1b, placing second constraining rebar 3 (reinforcement). The second restraining reinforcing bar 3 (reinforcing material) is a reinforcing bar formed substantially in a straight line, and bent portions 3a for fixing to concrete are formed at both ends. The first constraining reinforcing bar 2 and the second constraining reinforcing bar 3 are arranged so that the bent portions 2a and 3a overlap each other, thereby increasing the constraining force of the internal concrete 1b.

[Second Embodiment]
Moreover, as shown in FIG. 2 , in order to bear the shear stress which arises in the internal concrete 1b, you may arrange | position the shear reinforcement bar 4 (reinforcement material). The shear reinforcing bar 4 is a reinforcing bar formed substantially in a straight line, and bent portions 4a for fixing to concrete are formed at both ends. Place the bent part 2a of the first constraining reinforcing bar 2 and the bent part 4a of the shear reinforcing steel bar 4 facing each other in the short direction of the concrete pier 1 so as to overlap the inner concrete with shear stress. The binding force of 1b is improved. Moreover, by arrange | positioning so that the space | interval of the 1st restraint reinforcement 2 which opposes may be fixed, the deformation | transformation to the outer side of a 1st restraint reinforcement is restrained and the restraint effect with respect to the internal concrete 1b is improved. In this case, the amount of reinforcing bars of the shear reinforcement may be a necessary amount determined from the cross-sectional area of the concrete, and the amount of reinforcing bars can be reduced as compared with the conventional case.

According to the first and second embodiments, the compression side is partially constrained and the entire inner concrete 1b is constrained, so that the amount of reinforcing material can be reduced compared to the conventional case, and the arrangement work is performed. Can be improved.

It is a figure which shows the highly deformable performance concrete member which is 1st Embodiment, (a) is a perspective view, (b) is a cross-sectional view. It is a figure which shows the highly deformable performance concrete member which is 2nd Embodiment, (a) is a perspective view, (b) is a cross-sectional view.

Explanation of symbols

1 Concrete pier (concrete member)
DESCRIPTION OF SYMBOLS 1a Plastic hinge area 1b Inner concrete 2 1st restraint reinforcing bar 2a Bending part 3 2nd restraining reinforcing bar 3a Bending part 4 Shear reinforcement reinforcement 4a Bending part 20 Axial reinforcement 21 Band reinforcement

Claims (2)

A concrete member having an arbitrary cross-sectional shape in which axial reinforcing bars are arranged,
In the plastic hinge section formed by an external force acting on the concrete member, a plurality of first restraining reinforcing bars that partially restrain the compression side of the inner concrete are arranged along the compression edge inside the axial reinforcing bars. And
The first restraining reinforcing bar is formed in a semicircular arc shape, and is a reinforcing bar in which bent portions for fixing to the inner concrete are formed at both ends,
The semicircular arc-shaped first restraining reinforcing bars are arranged with the arc side facing the compression edge, and are arranged symmetrically with respect to the central portion in the thickness direction of the concrete member ,
Between the bent portions at both ends of the first restrained reinforcing bar, a second restrained reinforcing bar that is formed in a straight line and has bent portions at both ends is disposed. A high-deformation performance concrete member characterized in that the bent portion of the second and the bent portion of the second restraining reinforcing bar overlap . A concrete member having an arbitrary cross-sectional shape in which axial reinforcing bars are arranged,
In the plastic hinge section formed by an external force acting on the concrete member, a plurality of first restraining reinforcing bars that partially restrain the compression side of the inner concrete are arranged along the compression edge inside the axial reinforcing bars. And
The first restraining reinforcing bar is formed in a semicircular arc shape, and is a reinforcing bar in which bent portions for fixing to the inner concrete are formed at both ends,
The semicircular arc-shaped first restraining reinforcing bars are arranged with the arc side facing the compression edge, and are arranged symmetrically with respect to the central portion in the thickness direction of the concrete member,
Between the opposing bent parts of the first constrained reinforcing bars arranged symmetrically, shear reinforcing reinforcing bars with bent parts formed at both ends are arranged, and these first constrained reinforcing bars are bent. high Ductility concrete member you characterized in that part and the bent portion of the shear reinforcement rebar overlap.

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