JPH061010B2 - Seismic retrofitting method for existing concrete columns - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to a method for earthquake-proofing reinforcement of an existing concrete column.

<Conventional technology> Some existing structures were constructed according to old design standards and guidelines, so they are inferior in seismic performance and require seismic retrofitting. There are times when it is necessary.

A typical conventional seismic strengthening method is to surround an existing column member with a steel plate, or to surround an existing column member with a welded wire net or a rebar cage, mainly improving the toughness of the column member, that is,
Reinforcement methods have been proposed which are intended not to reduce the loading capacity and energy consumption capacity even if some damage such as cracking occurs.

<< Problems to be Solved by the Invention >> However, in this reinforcing method, welding work of a steel sheet or the like is indispensable on site, and unless the welding is surely performed by a skilled person, desired reinforcement can be obtained. I can't.

In addition, stress is transmitted by injecting mortar or the like between the existing column members and the steel plate, welded wire mesh, and rebar cage, but it is possible to densely fill the injected mortar between them. was difficult.

Further, generally, in the above-mentioned reinforcement method, slits are provided at the end of the reinforcement member such as a steel plate in order to increase only the shear strength of the existing column member and make the bending strength the same as before the reinforcement. The member located at the position has a drawback in that the rain habit of this part is deteriorated, and as a result, a water leakage accident is likely to occur.

Furthermore, in the reinforcing method using a steel plate, there is a problem that the steel plate needs to be subjected to rust preventive measures, which increases maintenance costs.

The present invention has been made in view of the above problems, and an object thereof is to effectively seismically retrofit existing column members by a simple operation such as winding a high-strength long fiber strand around an existing column. is there.

<< Means for Solving Problems >> The applicant of the present application has previously proposed a method of winding a high-strength long fiber strand around a column member in a double spiral shape as a column reinforcing method (Japanese Patent Application No. 59-273357). . According to this method, high-strength long fiber strands as a reinforcing material have a function as a spiral hoop of a reinforced concrete column, and both effects of increasing the strength and toughness of the column can be expected.

However, when concrete cracks occur in a column reinforced by this method and stress concentrates on the strands near the crack and the strand breaks once, the restraining force of this strand sharply decreases and the reinforcing effect remarkably decreases. It was learned.

The present invention is based on the above knowledge,
According to the seismic retrofitting method for existing concrete columns, high-strength long fiber strands are wound around the existing concrete columns in a spiral spiral shape on the upper right and the lower right, and the strands are bonded to each other at the intersections. It will be.

<Example> Hereinafter, a preferred example of the present invention will be described with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes an existing column. In this existing column 1, a high-strength long-fiber strand 2 is spirally formed to the upper end in a center portion of the existing column 1 and is wound up to an upper end portion. A downward spiral is wound up to the lower end, and the lower end is folded up again to form an upper right spiral to integrally connect the start end and the end with an adhesive at the center of the pillar.

As the high-strength long fiber strand 2, about 6000 monofilaments of carbon fiber are bundled and impregnated with resin in advance, or wound and impregnated to form a strand. However, the fibers used are not limited to carbon fibers, and glass fibers, vinylon fibers, and aramid fibers may be used. The resin is not particularly limited as long as it is used for the fiber reinforced resin, but an epoxy resin or the like is generally used. The number of filaments can be appropriately determined.

In the present invention, as described above, the double spiral strand 2 composed of the upper right spiral and the lower right spiral is integrally bonded to each other at the crossing portion 3 with an adhesive.

The bonding at the intersecting portion 3 can be performed very easily by winding the strand 2 in a double spiral and then applying a resin such as an epoxy resin only to the intersecting portion. Separately from this, the uncured resin is impregnated into the strand 2 in advance, and the strand 2 is wound in the form of a spiral spiral as described above, and the intersecting portions are integrally bonded by the mutual resin. You may do it.

<Effect> As described above, according to the method of the present invention, the high-strength long-fiber strands are wound around the existing concrete columns in a double spiral shape with the upper right and the lower right, and the strands are bonded to each other at the intersections. Therefore, even if concrete cracks and stress concentrates on the strand near the crack and the strand breaks, this strand is usually either the upper right or the lower right strand wound in a tabular spiral. Therefore, the remaining strand without breaking can bear the proof stress, and the breaking of one strand only affects the strand in a limited narrow range, and the strands in other ranges are the same as before. Similarly, since it is possible to maintain the restraint force, it is possible to exert an extremely excellent seismic reinforcement effect without significantly reducing the reinforcement effect. You can

Further, since no steel material is used, there is no need for anticorrosion treatment and no welding work. In addition, since there are no slits on the upper and lower ends of the pillars, there is no need to worry about rain.

[Brief description of drawings]

The figure is an explanatory view showing a method for seismic strengthening an existing concrete column according to the present invention. 1 ... Pillar 2 ... Strand 3 ... Crossover

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-151371 (JP, A) Sekikai-Sho 53-159115 (JP, U) JP-B-56-33542 (JP, B2) JP-B-53- 16214 (JP, B2)

Claims (1)

[Claims] 1. A concrete product characterized in that a high-strength long-fiber strand is wound around an existing concrete column in a double-spiral shape with an upper right direction and a lower right direction, and the strands are bonded to each other at their intersections. Seismic retrofitting method for existing columns.