JPH0573865B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a seismic reinforcement method for existing concrete columns.

≪Conventional technology≫ Some existing structures have been built according to old design standards and guidelines and therefore have poor seismic performance and require seismic reinforcement, or for reasons such as increasing the number of building floors when extending or renovating a structure. There are cases where reinforcement is required.

Typical conventional seismic reinforcement methods include surrounding existing column members with steel plates, or surrounding existing column members with welded wire mesh or reinforcing bar cages, mainly to improve the toughness of the column members, that is, to prevent cracks, etc. Reinforcement methods have been proposed that are intended to not reduce the loading capacity and energy consumption capacity even after some damage.

≪Problems to be solved by the invention≫ However, this reinforcement method requires welding of steel plates on site, and unless the welding is reliably performed by a highly skilled person, the desired reinforcement cannot be achieved. is not obtained.

Additionally, mortar, etc., will be injected between the existing column members and the steel plates, welded wire mesh, and reinforcing bar cages in order to transmit stress, but it is not possible to fill the injected mortar densely between these. It was difficult.

Furthermore, in the above-mentioned reinforcement methods, slits are generally provided at the ends of reinforcing members such as steel plates in order to increase only the shear strength of existing column members and maintain the same bending strength as before reinforcement. In the case of members located in this area, the rainwater is not well protected in this area, and as a result, water leakage accidents are more likely to occur.

Furthermore, in the reinforcing method using steel plates, rust prevention measures must be taken on the steel plates, resulting in an increase in maintenance and management costs.

The present invention was made in view of the above-mentioned problems, and its purpose is to effectively reinforce earthquake resistance of existing column members by a simple operation of winding high-strength long fiber strands around existing columns. be.

≪Means for solving the problem≫ The present applicant previously proposed a method of winding high-strength long fiber strands in a spiral shape on the surface of reinforced concrete columns as an earthquake reinforcement method (Japanese Patent Application No. 1982-
273357). This method allows the high-strength long fiber strands used as reinforcing materials to function as spiral hoops for reinforced concrete columns, and is expected to have the effect of both increasing the strength and toughness of the columns.

However, as a result of repeated experiments with the above method, we found that when high-strength long fiber strands are firmly bonded to concrete columns, it is possible to suppress the initial cracks in the columns, but once cracks occur, the cracks are Stress concentrates on the strands, causing them to break at a relatively early stage.On the other hand, when the strands are wound around concrete columns without being bonded, there is an effect of suppressing the initial cracking of the columns. Although this cannot be expected, it has been found that it exerts a large binding force after cracks occur.

The present invention has been made based on the knowledge as described above, and according to the seismic reinforcement method for existing columns, a first high-strength long fiber strand is wound around an existing concrete column using an adhesive. At the same time, a second high-strength long fiber strand is wound in an unbonded state overlapping this strand.

Preferably, a synthetic resin film such as a polyethylene film is interposed between the first high-strength long fiber strand and the second high-strength long fiber strand as an edge cutting material.

<<Example>> Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

In the figure, 1 indicates an existing pillar, and this existing pillar 1
A high-strength long fiber strand 2 is wound in a continuous spiral. This strand 2 is impregnated with a resin such as uncured epoxy resin or unsaturated polyester resin, and as this resin hardens, the strand 2 is firmly adhered to the existing column 1. In addition to bonding the strand 2 and the existing pillar 1 in this way, the existing pillar 1 is coated with adhesive in advance, and the high-strength long fiber strand 2 that is not impregnated with resin is applied to the existing pillar from above the adhesive. It is also possible to wind it over 1.

The high-strength long fiber strand 2 is made by bundling approximately 6,000 carbon fiber monofilaments and pre-impregnating them with a resin, or by winding them and impregnating them into a strand. However, the fibers used are not limited to carbon fibers, but may also include glass fibers, vinylon fibers, and aramid fibers. The resin is not particularly limited as long as it is used for fiber-reinforced resins, but epoxy resins and the like are generally used. Note that the number of filaments can be determined as appropriate.

In the present invention, the strand 2 wound as described above is coated with a synthetic resin film 3 such as a polyethylene film as an edge cutting material, and a second high-strength long fiber strand 4 is further placed on top of this film 3. wind up. At this time as well, the second high-strength long fiber strand 4 is impregnated with resin, but the resin does not adhere to the edge cutting material.
The strand 4 will be hemmed off from the first strand 2.

In the above embodiment of the present invention, the synthetic resin film 3 was interposed between the first strand 2 and the second strand 4 as an edge cutting material, but the adhesive on the first strand was completely solidified. By winding the second strand later and using an impregnated resin that has low adhesive strength with the first strand, the edge trimming material described above can be omitted. Further, as the edge cutting material mentioned above, it is conceivable to apply an oil-based paint or the like on the first strand 2 in addition to the synthetic resin film.

In the illustrated embodiment of the present invention, the winding pitches of the first strand 2 and the second strand 4 are shown to be different, but this is done so that the first strand and the second strand can be distinguished in the drawings. This was done for convenience, and it goes without saying that the pitches of both strands may be the same. In addition, in the illustrated example, the first
Although the winding directions of the second strand and the second strand are both upward to the right, one direction may be downward to the right so that both strands intersect.

<<Effects>> As described above, in the seismic reinforcement method for existing columns according to the present invention, a first high-strength long fiber strand is wound around an existing concrete column via an adhesive, and a second Because the high-strength long fiber strands are wound in an unbonded state, the first strand suppresses the occurrence of initial cracks and increases the strength of the existing column, causing cracks to occur in the existing column and stress in the cracked area. Even if the first strand breaks in a concentrated manner, this stress will be dispersed and propagated to the second strand, and the second strand will not break, so this second strand will firmly constrain the existing column 1. This prevents collapse and increases the toughness of the column.

As described above, in the present invention, the first strand increases the strength of the existing column, and the second strand increases the toughness of the existing column, so both strands significantly improve earthquake resistance.

Furthermore, since no steel material is used, there is no need for anti-rust treatment, and no welding work is required. Also, since there are no slits on the top and bottom ends of the pillars, there is no need to worry about rain.

[Brief explanation of the drawing]

The figure shows an example of reinforcing an existing column according to the present invention, and is a partially cutaway side view of the lower part thereof. 1... Existing pillar, 2... First high strength long fiber strand, 3... Edge cutting material, 4... Second high strength long fiber strand.

Claims (1)

[Claims] 1. A first high-strength long fiber strand is wound around an existing concrete column via an adhesive, and a second high-strength long fiber strand is wound in an unadhered state overlapping the strand. A seismic reinforcement method for existing columns that is characterized by 2. The method according to claim 1, wherein a synthetic resin film is interposed as an edge cutting material between the first high-strength long fiber strand and the second high-strength long fiber strand. Seismic reinforcement method for existing columns.