JP4014774B2 - Reinforced concrete members - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reinforced concrete member.
[0002]
[Prior art and problems to be solved by the invention]
In a reinforced concrete structure that is not equipped with a special damping device such as a damper, seismic energy is absorbed by damage to reinforced concrete members such as columns and beams during a large earthquake. Therefore, after the earthquake, residual deformation and residual cracks occur, and the repair is expensive.
On the other hand, there is a prestressed concrete structure as a structure for controlling residual deformation and residual cracking. However, prestressed concrete structures are expensive to construct and have problems such as large shaking during an earthquake, and cannot be said to be a general-purpose frame construction method.
[0003]
Damage to reinforced concrete structures during a large earthquake depends on the residual deformation of each reinforced concrete member due to seismic force. In order to reduce this deformation, it is necessary to increase the strength and rigidity of the reinforced concrete members such as columns and beams. For this purpose, the cross-sectional dimensions of the reinforced concrete members must be increased. In this method, not only the construction cost increases, but also the disadvantage of usability due to the narrowing of the living space occurs.
If the residual deformation of a reinforced concrete member after a major earthquake can be reduced with a cross-sectional dimension comparable to that of a conventional reinforced concrete member and without any additional damper or other damping device, the repair cost of the reinforced concrete structure damaged by the earthquake can be reduced. It can be greatly reduced.
[0004]
In view of the above circumstances, the present invention provides a reinforced concrete member having a cross-sectional dimension comparable to that of a conventional reinforced concrete member and capable of reducing residual deformation after the application of an external force such as seismic force without particularly providing a vibration control device. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a reinforced concrete member (reinforced concrete beam) 1 according to claim 1 (see, for example, FIGS. 1 and 2)
In the reinforced concrete member 1 in which the reinforcing bar 3 is arranged in the concrete 2,
In the concrete 2, a high-strength reinforcing bar 4 having a strength higher than that of the reinforcing bar 3 is arranged, and this high-strength reinforcing bar 4 is in an elastic range even if an external force acts on the reinforced concrete member 1 and the reinforcing bar 3 becomes plastic. The residual deformation of the reinforced concrete member 1 is reduced by its restoring force.
[0006]
According to the reinforced concrete member according to claim 1, since the elastic limit strain of the high-strength reinforcing bar is larger than that of the reinforcing bar, when the external force acts on the reinforced concrete member to cause deformation, the reinforcing bar Even when plasticized, the high-strength reinforcing bar remains in the elastic range, and after the action of the external force is finished, the residual deformation of the reinforced concrete member can be reduced by the restoring force of the high-strength reinforcing bar.
Also, without increasing the cross-sectional dimensions of the reinforced concrete members, and without any additional damping device such as a damper, it is possible to perform residual deformation after the application of external forces such as seismic force with relatively simple construction and low cost. Can be small.
[0007]
Furthermore, the reinforced concrete member 1 (for example, refer FIG. 2) of Claim 1 is the following.
The high-strength reinforcing bar 4 is arranged near the center of the cross section of the reinforced concrete member 1.
[0008]
Therefore, according to the reinforced concrete member according to claim 1, when an external force acts on the reinforced concrete member to cause bending deformation, the high-strength reinforcing bar is disposed near the center of the cross section near the neutral axis. The high-strength reinforcing bar can be reliably retained within the elasticity, and the residual deformation of the reinforced concrete member can be reduced by the restoring force of the high-strength reinforcing bar.
A reinforced concrete member 1 according to claim 2 (see, for example, FIG. 1),
In the plastic hinge region 5 formed in the reinforced concrete member 1 when an external force is applied to the reinforced concrete member 1, the adhesion between the concrete 2 and the high strength reinforcing bar 4 is removed.
[0010]
According to the reinforced concrete member of the second aspect, the same effect as that of the first aspect can be obtained, and the adhesion between the concrete and the high-strength reinforcing bar is removed in the plastic hinge region of the reinforced concrete member. The stress applied to the high strength reinforcing bars in the hinge area is dispersed. Therefore, even when the reinforced concrete member is deformed greatly, the high-strength reinforcing bar can be reliably retained within the elasticity, and the residual deformation of the reinforced concrete member can be reduced by the restoring force of the high-strength reinforcing bar.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Below, the embodiment of the reinforced concrete member of the present invention is described based on a drawing.
FIG. 1 is a side view showing a reinforced concrete beam (reinforced concrete member) 1 according to the present embodiment, and FIG. 2 is a cross-sectional view taken along the line AA.
[0012]
In the reinforced concrete beam 1 according to the present embodiment, in a reinforced concrete member 1 in which a reinforcing bar 3 is arranged in a concrete 2, a high-strength reinforcing bar 4 having a higher strength than the reinforcing bar 3 is arranged in the concrete 2. Even if an external force acts on the reinforced concrete member 1 and the reinforcing bar 3 becomes plastic, the strength reinforcing bar 4 remains in the elastic range, and its restoring force reduces the residual deformation of the reinforced concrete member 1. ing.
[0013]
Here, as shown in FIG. 2, the high-strength reinforcing bar 4 is arranged near the center of the cross section of the reinforced concrete beam 1.
[0014]
Further, in the plastic hinge region 5 shown in FIG. 1 formed in the reinforced concrete member 1 when an external force acts on the reinforced concrete member 1, the adhesion between the concrete 2 and the high-strength reinforcing bar 4 is shown in FIG. Thus, the outer periphery of the high-strength reinforcing bar 4 is removed by covering it with the wax 4a.
[0015]
As described above, according to the reinforced concrete beam 1 of the above embodiment, the elastic limit strain of the high-strength reinforcing bar 4 is larger than that of the reinforcing bar 3, so when an external force acts on the reinforced concrete beam 1 to cause deformation, Even if the reinforcing bar 3 is plasticized, the high-strength reinforcing bar 4 remains in the elastic range, and after the action of the external force is finished, the residual deformation of the reinforced concrete beam 1 can be reduced by the restoring force of the high-strength reinforcing bar 4. it can.
In addition, the residual deformation after the application of external force such as seismic force is relatively simple and low cost without increasing the cross-sectional dimension of the reinforced concrete member 1 and without any additional damping device such as a damper. Can be reduced.
[0016]
Further, when an external force acts on the reinforced concrete beam 1 to cause bending deformation, the high-strength reinforcing bar 4 is arranged near the center of the cross section close to the neutral axis, so that the high-strength reinforcing bar 4 is reliably elastic. The residual deformation of the reinforced concrete member 1 can be reduced by the restoring force of the high-strength reinforcing bar 4.
[0017]
Further, since the adhesion between the concrete 2 and the high-strength reinforcing bar 4 is removed in the plastic hinge region 5 of the reinforced concrete beam 1, the stress applied to the high-strength reinforcing bar 4 in the plastic hinge region 5 is dispersed. Therefore, even when the reinforced concrete beam 1 is largely deformed, the high-strength reinforcing bar 4 can be reliably retained within the elasticity, and the residual deformation of the reinforced concrete beam 1 can be reduced by the restoring force of the high-strength reinforcing bar 4. it can.
[0018]
In addition, the reinforced concrete member of this invention is not limited to the said embodiment, You may perform various improvement and design change in the range which does not deviate from the meaning of this invention.
For example, in the above embodiment, the reinforced concrete beam is taken up, but the reinforced concrete member of the present invention may be applied to, for example, a column, a waist wall, a sleeve wall, a vertical wall, and the like.
Further, in the above embodiment, the adhesion between the concrete 2 and the high-strength reinforcing bar 4 is removed by covering the outer periphery of the high-strength reinforcing bar 4 with the wax 4a. For example, the high-strength reinforcing bar in the plastic hinge region 5 is removed. The adhesion between the concrete 2 and the high-strength reinforcing bars 4 may be removed by removing and smoothing the deformed reinforcing bar ribs on the four surfaces and applying grease or the like to the surface.
In addition, it is needless to say that specific detailed structures and the like can be appropriately changed.
[0019]
(Experimental example)
An experimental example related to the reinforced concrete member of the present invention is shown below.
As shown in FIG. 3, on both ends of the reinforced concrete member A according to the present invention and the reinforced concrete member B by a normal reinforcement method for comparison, assuming the seismic force applied to the beam, positive and negative alternation under no axial force The amount of deformation in the axial direction of the reinforced concrete members A and B when a repetitive reverse bending moment was applied was calculated by numerical analysis.
[0020]
The cross-sectional dimensions of the reinforced concrete members A and B are a beam formation of 800 mm, a beam width of 400 mm, and a length of 5000 mm. As shown in FIG. 3A, the reinforced concrete member A has eight reinforcing bars 13 and four high-strength reinforcing bars 14, and the reinforced concrete member B has a reinforcing bar as shown in FIG. 3B. , Twelve reinforcing bars 13 are arranged.
[0021]
Reinforcing bar 13 has a yield stress level σ _y of 345 N / mm ² and a cross-sectional area of 5.067 cm ² (corresponding to Japanese Industrial Standard SD345, D25). High-strength reinforcing bar 14 has a yield stress level σ _y of 685 N. / Mm ² , and the cross-sectional area per one was 2.865 cm ² (corresponding to Japanese Industrial Standard SD685, D19).
In both the reinforced concrete members A and B, the compressive strength of the concrete 12 was 21 N / mm ² .
The stress σ-strain ε relationship of the reinforcing bar 13 and the high-strength reinforcing bar 14 assumes a perfect elastoplasticity as shown in FIG. 5, and the stress σ-strain ε relationship of the concrete 12 is a trilinear type as shown in FIG. Hysteresis was assumed.
[0022]
Further, in the reinforced concrete member A, in the plastic hinge region at both ends in the material axis direction, as shown in FIG. 4, the adhesion between the concrete 12 and the high-strength rebar 14 is removed over a length of 800 mm from the material end. It is assumed that the strain of the high-strength reinforcing bar 14 is uniform in this adhesion removal portion.
The adhesion between the high-strength reinforcing bar 14 or the reinforcing bar 13 and the concrete 12 other than the above is assumed to be complete, and the assumption of plane maintenance is satisfied.
[0023]
The reverse bending rotation angles given to both ends of the reinforced concrete members A and B are ± 1/200 rad for the maximum value in the first cycle and ± 1/150 rad and ± 1/100 rad for the maximum values in the second to fourth cycles, respectively. , ± 1/67 rad in order, and then the rotation angle of the maximum value ± 1/50 rad was given for two cycles in the fifth and sixth cycles.
[0024]
The results of this numerical analysis experiment are shown in FIG.
From this result, the residual deformation amount in the final material axial direction of the reinforced concrete member A is 8.0 mm, which is 62% of the residual deformation amount in the final material axial direction of the reinforced concrete member B of 12.9 mm, and the reinforced concrete member to which the present invention is applied. It was confirmed that the residual deformation of A is smaller than the residual deformation of the reinforced concrete member B by the normal ordinary bar arrangement method.
[0025]
【The invention's effect】
According to the reinforced concrete member according to claim 1, since the elastic limit strain of the high-strength reinforcing bar is larger than that of the reinforcing bar, when the external force acts on the reinforced concrete member and deforms, the reinforcing bar is plastic. Even if the strength is increased, the high-strength reinforcing bar remains in the elastic range, and after the action of the external force is finished, the residual deformation of the reinforced concrete member can be reduced by the restoring force of the high-strength reinforcing bar.
Also, without increasing the cross-sectional dimensions of the reinforced concrete members, and without any additional damping device such as a damper, it is possible to perform residual deformation after the application of external forces such as seismic force with relatively simple construction and low cost. Can be small.
[0026]
Furthermore, according to the reinforced concrete member according to claim 1, when an external force acts on the reinforced concrete member to cause bending deformation, the high-strength reinforcing bar is arranged near the center of the cross section near the neutral axis. The high-strength reinforcing bar can be reliably retained within the elasticity, and the residual deformation of the reinforced concrete member can be reduced by the restoring force of the high-strength reinforcing bar.
[0027]
According to the reinforced concrete member of the second aspect, the same effect as in the first aspect can be obtained, and the adhesion between the concrete and the high-strength reinforcing bar is removed in the plastic hinge region of the reinforced concrete member. The stress applied to the high-strength reinforcing bars in the region is distributed. Therefore, even when the reinforced concrete member is deformed greatly, the high-strength reinforcing bar can be reliably retained within the elasticity, and the residual deformation of the reinforced concrete member can be reduced by the restoring force of the high-strength reinforcing bar.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of a reinforced concrete member of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA in FIG.
FIGS. 3A and 3B show test subjects in an experimental example, in which FIG. 3A is a cross-sectional view of a reinforced concrete member A, and FIG. 3B is a cross-sectional view of a reinforced concrete member B;
4 is a side view of the reinforced concrete member A. FIG.
FIG. 5 is a diagram showing a stress-strain relationship of concrete in an experimental example.
FIG. 6 is a view showing a stress-strain relationship between a reinforcing bar and a high-strength reinforcing bar.
FIG. 7 is a diagram showing the results of an experimental example.
[Explanation of symbols]
1 Reinforced concrete members (reinforced concrete beams)
2,12 Concrete 3,13 Reinforcing bars 4,14 High-strength reinforcing bars 5 Plastic hinge area

Claims (2)

In reinforced concrete members with reinforcing bars in concrete,
In the concrete, high-strength reinforcing bars with higher strength than the reinforcing bars are arranged,
This high-strength reinforcing bar remains in the elastic range even if an external force acts on the reinforced concrete member and the reinforcing bar becomes plastic, and its restoring force reduces the residual deformation of the reinforced concrete member. A reinforced concrete member arranged near the center .   The reinforced concrete member according to claim 1, wherein adhesion between the concrete and the high-strength reinforcing bar is removed in a plastic hinge region formed in the reinforced concrete member when an external force is applied to the reinforced concrete member.

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