JPH09250111A - Stripping prevention structure for covering materials and cover concrete - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a covering material and a covering concrete peeling-preventing structure capable of preventing the covering material such as overcast concrete from peeling off even after the yielding of the main bar and preventing local buckling of the main bar. To provide. SOLUTION: In a reinforcing structure in which reinforcing bars 11 and 12 are arranged on the outer circumference of an existing concrete columnar body 21 and the existing concrete columnar body is covered with a covering material 14 such as concrete or cement mortar on the reinforcing bar, The slit 16 was formed in the covering material near the joint between the body and the foundation footing 23 and the beam member 22. Also,
Slits 16 'were formed in the cover concrete 24 near the joint between the existing concrete columnar body and the foundation footing and / or beam member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a covering material and a structure for preventing concrete from falling off, and more specifically, to peeling off a covering material newly wound around the outer periphery of an existing concrete columnar body or covering the concrete columnar body. The present invention relates to a structure for preventing concrete from falling off.

[0002]

2. Description of the Related Art As a reinforcing structure for an existing concrete columnar body, that is, an existing concrete column such as a bridge pier or a building, there is a so-called RC roll-up reinforcing structure. With this conventional RC roll-up reinforcement structure, a main bar and a band are newly provided on the outer circumference of an existing concrete column, a formwork is installed on this outer circumference, and concrete as a new covering material is placed in the formwork, It is formed by demolding the mold after hardening the concrete.

[0003]

If a seismic force exceeding the allowable proof stress acts on the conventional RC roll-up reinforcing structure, local buckling of the main bars occurs. In this local buckling phenomenon of the main bar, first, the RC winding column vibrates in the horizontal direction and tensile stress acts, and the main bar such as a section where the main bar density decreases, especially the newly installed main bar yields. Then, when a compressive stress is applied to the location, the overlying concrete covering the new main bar is peeled off, the yielded main bar buckles, and the stirrup also comes off.

Further, the above-mentioned local buckling phenomenon similarly occurs in a concrete columnar body not provided with a reinforcing structure, which may cause exfoliation of covered concrete.

The local buckling of the main bars can be delayed by increasing the bar arrangement density of the stirrups, but there is a drawback that if the bar arrangement density is too high, the filling property of concrete decreases. However, even if the reinforcement density of the stirrup is increased, it has no effect on the prevention of exfoliation of the cover concrete.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to prevent the covering material such as overlaid concrete from peeling off even after the yielding of the main bar, so that the main bar is localized. It is an object of the present invention to provide a covering material capable of preventing buckling and a structure for preventing exfoliation of cover concrete.

[0007]

The present invention has been made in view of the above-mentioned object, and the gist thereof is to dispose reinforcing bars on the outer periphery of an existing concrete columnar body, and to add existing reinforcing concrete from above the reinforcing bars. In a reinforced structure in which a columnar body is covered with a covering material such as concrete or cement mortar,
In the structure for preventing the covering material from coming off, a slit is formed in the vicinity of the joint between the concrete columnar body and the foundation footing and / or the beam member.

Here, in the structure for preventing the covering material from falling off according to the present invention, the reinforcing bars to be newly arranged on the outer periphery of the existing concrete columnar body are only stirrups, main stirrups and stirrups, or main stirrup and stirrups and wire mesh Any of the combinations of the mesh bodies such as Further, as the coating material, for example, the above-mentioned concrete or cement mortar can be used. Furthermore, the slit is
In the concrete columnar body, it is formed only at the upper and lower ends, that is, only the covering material around the entire column in the vicinity of the joint with the foundation footing or the beam member, or at a predetermined depth up to the covering concrete of the existing concrete columnar body.

[0009] Another subject matter of the present invention is a structure for preventing exfoliation of cover concrete, characterized in that a slit is formed in the cover concrete near the joint between the concrete columnar body and the foundation footing and / or beam member.

In the structure for preventing the covering material and the cover concrete from falling off according to the present invention, the slits formed in the covering material and the cover concrete may be filled with an elastic member. When a bending stress is generated in the columnar body, the beam member and the foundation footing joined to the upper and lower ends of the columnar body must be flexible enough to be deformed so as not to constrain the covering material and the cover concrete. For example, it may be filled with an amorphous sealing material such as polysulfide-based, acrylic-based or urethane-based material, or may be filled with a preformed material such as synthetic rubber.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a stripping-off prevention structure for a covering material of the present invention, FIG. 2 is a partial cross-sectional view of FIG. 1, and FIG. 3 is a cross-sectional view showing a stripping-off prevention structure for covered concrete.
In FIG. 1, an existing concrete column 21 to which the exfoliation prevention structure of the present invention is applied has a beam 11 integrally formed at its upper end and a foundation footing 23 integrally formed at its lower end. RC winding reinforcement is done over the entire length. This RC roll-up reinforcement is an additional main reinforcement 1 on the outer circumference of the existing concrete column 21 in the axial direction.
1 is fixed by an anchor or the like, the additional reinforcement bar 12 is wound on the additional main reinforcement 11, and the additional main reinforcement 11 and the additional reinforcement 12 are covered with the additional concrete 14.

In the present invention, in the existing concrete column 21 thus reinforced by RC winding, as shown in FIG. 2, the slits 16 are formed around the entire upper and lower ends. Here, the depth D of the slit 16 should be the thickness of the additional concrete 14, and the slit height H should be 0.25 times the column width or more and 1/2 or less of the interval between the additional stirrups 12 and 12. In addition, the slit 16 is filled with a filler 13 that is preformed by an elastic material such as synthetic rubber. further,
The additional main reinforcement 11 exposed in the slit 16 is subjected to rust prevention treatment such as epoxy coating.

In the structure for preventing the covering material from falling off according to the present invention described above, since the slits 16 are formed at the upper and lower ends of the existing concrete columns 21 around the entire circumference of the additional concrete 14, the additional concrete 14 is used for the beam 11 and foundation footing. Two
Even if horizontal vibration acts on the existing concrete column 21 without being restrained by 3, the transmission of compressive stress or tensile stress from the beam 11 or the foundation footing 23 to the additional concrete 14 can be prevented, so that the additional concrete 14 can be removed. Can be suppressed. Therefore, even if the additional main reinforcing bar 11 yields, the additional main reinforcing bar 11 is restrained without the additional concrete 14 coming off, so that the local buckling of the additional main reinforcing bar 11 can be prevented.

Next, a description will be given of a structure for preventing the concrete 24 from being covered with seismic concrete 24 without seismic reinforcement, with reference to FIG. The exfoliation prevention structure for cover concrete of the present invention, in the concrete column 21,
Slits 16 'are formed around the entire upper and lower ends. Here, the depth D of the slit 16 'is less than or equal to twice the thickness of the covering concrete 24 of the main bar 11', and the covering concrete 2
The slit height H may be 0.25 times or more the column width and 1/2 or less of the interval between the stirrups 12 'and 12'. Further, as in FIGS. 1 and 2, the main bar 11 'is rust-proofed by epoxy coating or the like, and the slit 1
6'is filled with the filler 13.

The anti-stripping structure for covering concrete of the present invention has the same action and effect as the anti-stripping structure for covering material of an existing concrete column which has been reinforced by RC winding.
That is, since the slits 16 ′ are formed on the entire circumference of the overcast concrete 24 at the upper and lower ends of the concrete column 21, the overcast concrete 24 is not restrained by the beam 11 or the foundation footing 23, and its peeling is suppressed. Therefore, even if the main bar 11 'yields, the overcast concrete 24 does not peel off and restrains the main bar 11', preventing local buckling of the main bar 11 '.

[0016]

In the structure for preventing the covering material from falling off according to the present invention, since the slits are formed on the entire circumference of the existing concrete column in which the covering material is wound up, the covering material is formed by the joining members such as beams and foundation footings. It is not restrained, and it is possible to prevent the covering material from peeling off even after yielding of the main bar, and therefore,
Since the main bar is restrained by the covering material, it is possible to prevent local buckling.In addition, in the cover-prevention structure for covering concrete of the present invention, since the slits are formed in the covering concrete around the upper and lower ends of the concrete column, the covering The concrete is not restrained by the joining members such as beams and foundation footings, and the covering concrete can be prevented from peeling off even after the yielding of the main reinforcement. Therefore, since the main reinforcement is restrained by the covering concrete, local buckling must be prevented. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a peeling-off preventing structure for a covering material in an existing concrete columnar body provided with a reinforcing structure.

FIG. 2 is a partial cross-sectional view of FIG.

FIG. 3 is a cross-sectional view showing a structure for preventing exfoliation of covered concrete in a concrete columnar body.

[Explanation of symbols]

 11 Extension Main Bar (Reinforcing Bar) 12 Expansion Belt (Reinforcing Bar) 14 Expansion Concrete (Coating Material) 16, 16 'Slit 21 Existing Concrete Column 22 Beam (Beam Member) 23 Foundation Footing 24 Overcast Concrete

Claims (2)

[Claims] 1. A reinforcing structure in which reinforcing bars are arranged on the outer circumference of an existing concrete columnar body, and the existing concrete columnar body is covered with a covering material such as concrete or cement mortar on the reinforcing bar, wherein the concrete columnar body and the foundation are provided. A peeling-off prevention structure for a covering material, characterized in that a slit is formed in the vicinity of a joint with a footing and / or a beam member. 2. A peeling-preventing structure for overcast concrete, characterized in that a slit is formed in the overcast concrete in the vicinity of the joint between the concrete columnar body and the foundation footing and / or beam member.