JP2007002512A - Method of seismically retrofitting reinforced concrete column - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement fastening of an existing reinforced concrete column by means of straps simply and at low cost. <P>SOLUTION: In implementation of the fastening of the existing reinforced concrete column 1, the steel straps 10 are wound on the column 1 like loops, and a sealing fitting 12 is fitted to a superposed portion of each winding starting end and each winding terminal end. Then while each steel strap 10 is tightened by a handy-type binding tool, the sealing fitting 12 is locally caulked to rigidly bind the superposed portion. In this manner the reinforced concrete column 1 is fastened by a number of the steel straps 10 wound on the same at a predetermined pitch, and therefore the shear resistance of the reinforced concrete column 1 is enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a seismic reinforcement method for reinforcing an existing reinforced concrete column, and more particularly to a seismic reinforcement method for winding a strap around a reinforced concrete column and tightening it.

  As a seismic reinforcement method for reinforcing an existing reinforced concrete column, a steel plate reinforcement method (for example, see Patent Document 1) in which a steel plate is installed around a reinforced concrete column and mortar is injected into the gap between the steel plate and the reinforced concrete column, or 2. Description of the Related Art Conventionally, a fiber reinforcement method (for example, see Patent Documents 2 and 3) in which high-strength fibers such as carbon fibers or high-strength fiber sheets are wound around reinforced concrete columns is known. However, according to the steel plate reinforcement method, since welding work is required for installation of the steel plate, it is necessary to take measures against fire and, moreover, troublesome mortar injection work is necessary, and there are many problems in terms of workability. On the other hand, according to the fiber reinforcement method, the fiber or fiber sheet is simply wrapped around a reinforced concrete column and hardened with an adhesive, so that a large tightening force cannot be obtained, and in addition, construction is performed by using an expensive fiber material. There was a problem that the cost increased.

Thus, for example, in the seismic reinforcement method described in Patent Document 4, a belt-like tension member (strap) made of aramid fiber is wound around a reinforced concrete column in a loop shape, and a retaining ring portion formed in advance on both ends of the belt-like tension member is provided. The belt-like tension member is fastened by the fastening means (bolts, nuts, etc.) engaged. According to this construction method, in addition to increasing the shear strength of the existing reinforced concrete column by tightening with the strap, the material cost is reduced, and various problems in the fiber reinforcement construction method can be solved. If a steel strap is used instead of the belt-like tension member, mortar injection work including welding is not necessary, and various problems in the steel plate reinforcing method can be solved.
JP-A-9-32312 JP-A-11-324343 Japanese Patent Laid-Open No. 11-2030 Japanese Patent Laid-Open No. 2003-314065

  However, according to the seismic reinforcement method described in Patent Document 4, the troublesome work of fastening bolts and nuts is required, including the work of connecting fastening means to the retaining ring portions at both ends of the strap (band-like tension member). The improvement effect of workability is insufficient. In addition to the need to form a retaining ring part at both ends of the strap (end processing), many parts such as bolts and nuts are required as fastening means, and the effect of reducing construction costs is insufficient. It is.

  The present invention has been made in view of the above-mentioned conventional problems, and the problem is that it is possible to easily and inexpensively tighten an existing reinforced concrete column with a strap, thereby improving workability. The object is to provide a seismic reinforcement method that greatly contributes to shortening the construction time and the construction cost.

  According to a first invention for solving the above-mentioned problem, in the seismic reinforcement method for tightening a strap around an existing reinforced concrete column in a loop shape, a steel strap is selected as the strap, and the winding start end portion of the steel strap and The overlapping portion with the winding end portion is solidified through a seal fitting while being tightened using a handy type bundling tool.

  In the first invention, the reinforced concrete column can be easily tightened with the steel strap using the handy type binding tool. In addition, since only the seal fitting is required for fixing the steel strap, fastening means such as bolts and nuts as well as end processing on the strap become unnecessary, which is advantageous in terms of cost.

  According to a second invention for solving the above-mentioned problem, in the seismic reinforcement method of tightening a strap around an existing reinforced concrete column in a loop shape, a plastic band is selected as the strap, and a winding start end portion of the plastic band and The overlapping portion with the winding end portion is welded while being tightened using a handy type binding tool.

  In the second invention, similar to the first invention, it is possible to easily tighten a reinforced concrete column with a plastic band using a handy type bundling tool, but because the plastic band is consolidated by welding, All fastening members including the above-mentioned sealing metal fitting are unnecessary, which is extremely advantageous in terms of construction cost as well as workability.

  In the first and second inventions, when the reinforced concrete column has a quadrangular cross section, it is desirable to chamfer the corners of the reinforced concrete column in advance. In this case, the strap can be tightened efficiently. The strap breakage due to stress concentration can be prevented.

  According to the seismic reinforcement method for a reinforced concrete column according to the present invention, it is possible to easily and inexpensively tighten an existing reinforced concrete column with a strap, so that improvement of workability, shortening of construction time and reduction of construction cost can be achieved. .

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  1 and 2 illustrate one embodiment of the present invention. In the present embodiment, a steel strap 10 is wound around a reinforced concrete column 1 of an existing building in a loop shape, and the reinforced concrete column 1 is tightened by the steel strap 10. A number of steel straps 10 are wound around the exposed portion of the reinforced concrete column 1 located between the upper and lower beams 2 and 2 of the existing building at a predetermined pitch. The overlapping portion 11 (FIG. 2) with the (winding end portion) is solidified via a seal fitting 12 described later. Here, the reinforced concrete column 1 has a quadrangular cross section, and its four corners are chamfered by a slope 3 (which may be round). As an example, the steel strap 10 has a thickness of about 0.5 to 1.2 mm and a width of about 25 to 35 mm. Moreover, the winding pitch of the steel strap 10 with respect to the reinforced concrete pillar 1 is set to about 3-10 cm as an example.

  In this embodiment, winding and solidification of the steel strap 10 with respect to the reinforced concrete pillar 1 is performed using a handy type binding tool. This handy type bundling tool includes a dedicated tool for tightening the strap and a dedicated tool for fastening the overlapping portions at both ends of the steel strap 10 via the seal fitting 12. Such a special tool is commercially available as a set for ship hooplashing, under the names of “LT-60 type tensioner” and “LC-32 type sealer” from Kohan Kogyo. On the other hand, the seal fitting 12 is commercially available under the name of “Lashing seal” from the same steel industry as it is attached to the dedicated tool. As shown in FIG. 3, the seal fitting 12 has a C-shape, and its inner surface 12a is finished in a satin finish. In addition, the length of this seal metal fitting 12 is about 10 cm as an example.

  When winding and consolidating the steel strap 10 around the reinforced concrete column 1, a fixed size steel strap 10 is prepared by cutting in advance to a dimension obtained by adding a predetermined overlap to the peripheral length of the reinforced concrete column 1. First, the steel strap 10 is wound around the reinforced concrete column 1 and overlapped while passing through both ends of the steel strap 10 through the seal fitting 12, and next to the tensioner as the handy type binding tool, adjacent to the seal fitting 12. The overlapping portion 11 of the steel strap 10 is gripped, and the steel strap 10 is tightened by the operation of the tensioner. At this time, since the corners of the reinforced concrete column 1 are chamfered by the slope 3, the steel strap 10 can be tightened efficiently. Further, stress is not concentrated on the steel strap 10 due to the chamfering, and the steel strap 10 is prevented from being broken.

  Next, the sealer is engaged with the seal fitting 12 locked to the overlapping portion 11 of the steel strap 10, and the sealer is operated. Then, as shown in FIG. 2, both sides of the seal fitting 12 are caulked locally by the sealer (caulking portion 13), and the steel strap 10 is maintained at its starting end while being kept tightened by the tensioner. The overlapping portion 11 of the portion and the end portion is fixed through the seal fitting 12. In this case, since the matte inner surface 12a of the seal fitting 12 is pressed against the steel strap 10, a frictional resistance acts in the pulling direction, and coupled with the caulking by the caulking portion 13, the overlapping portions 11 ( The joint part) is firmly consolidated.

  The winding and consolidation of the steel strap 10 on the reinforced concrete column 1 is repeated at a predetermined pitch along the reinforced concrete column 1, whereby the reinforced concrete column 1 is made up of a number of steel straps 10 as shown in FIG. 1. Tightened. Further, the tightening by the large number of steel straps 10 increases the shear strength of the reinforced concrete column 1, and the reinforced concrete column 1 is remarkably excellent in earthquake resistance. Thus, since the metal fitting 12 used for consolidating the steel strap 10 has a flat shape, when the surface of the reinforced concrete column 1 is finished with mortar or the like, it can be made thin. Narrowing of the space is minimized.

  In addition, in the said embodiment, although the overlap part 11 of the both ends of the steel strap 10 was solidified with the one sealing metal fitting 12, you may solidify with two or more sealing metal fittings 12 in this invention. It is. FIG. 4 shows an embodiment in which the overlapping portions 11 at both ends of the steel strap 10 are secured by two seal fittings 12. Here, the two seal fittings 12 are arranged adjacent to each other. Yes. In this case, it is natural that the length of the overlapping portion 11 of the steel strap 10 is set longer than that in the above embodiment. In this way, by joining the overlapping portions 11 at both ends of the steel strap 10 with two or more seal fittings 12, the joint strength of the joint portion is increased, and the reliability with respect to seismic reinforcement is further improved.

  Moreover, in the said embodiment, although the steel strap 10 was wound around the reinforced concrete pillar 1 with predetermined | prescribed pitch (about 3-10 cm), this invention winds the steel strap 10 closely, without opening a clearance gap. In this case, the tightening effect of the reinforced concrete column 1 by the steel strap 10 is further improved. In the above embodiment, the steel strap 10 is wound once and both ends thereof are consolidated. However, in the present invention, a plurality of the steel straps 10 may be wound. As a result, the reliability of seismic reinforcement is further improved.

  Furthermore, in the above-described embodiment, a tensioner dedicated for tightening and a sealer dedicated for consolidation are used as a handy-type binding tool, and the steel strap 10 is tightened and consolidated in cooperation with both. In the case of using a handy type bundling tool capable of continuously performing consolidation and cutting with one unit, the steel strap 10 can be tightened and consolidated more efficiently. Moreover, in this case, since the excess part of the steel strap 10 can be cut automatically, it can be wound around the reinforced concrete column while pulling out the steel roll from the strap roll formed by winding the steel strap.

  Here, in the present invention, a plastic band can be selected as a strap used for tightening a reinforced concrete column instead of the steel strap 10. In this case, a plastic band having a tensile strength as excellent as possible is selected. As a plastic band excellent in tensile strength, for example, there is a polyester band frequently used as a heavy packing band. The plastic band is wound and consolidated on the reinforced concrete column using a handy type bundling tool as in the above embodiment. In this case, it is desirable to select one having a function capable of continuously performing tightening, welding and cutting of the plastic band. As such a handy type bundling tool, there is a plastic band tool marketed under the name of “MV type combination tool” by Kohan Kogyo.

  When a plastic band is wound and consolidated on a reinforced concrete column, the plastic roll is drawn out from a band roll formed by winding the plastic band, and is wound around the concrete column, and the winding start end and winding end The overlapping portion is gripped by the combination tool, and tightening, welding, and cutting are continuously performed. Thus, when the strap is consolidated by welding, no fastening member including the seal fitting 12 is required, and the workability is greatly improved as compared with the embodiment using the steel strap 10. The construction cost is greatly reduced. Of course, when the plastic band is wound around the reinforced concrete column, as in the case of the steel strap 10, it may be tightly wound without a gap or may be wound plurally.

It is a perspective view which shows one embodiment of this invention performed using a steel strap. FIGS. 2A and 2B show a solidified state of the steel strap in the embodiment shown in FIG. 1, and FIG. 2A is a perspective view showing a state on the front surface side, and FIG. It is a perspective view which shows the external appearance shape of the seal metal fitting used in embodiment shown in FIG. It is a perspective view which shows the solidified state of the steel strap using two sealing metal fittings.

Explanation of symbols

1 Reinforced concrete pillar 3 Slope (chamfering)
10 Steel Strap 11 Steel Strap Overlap 12 Seal Fitting 13 Caulking

Claims (3)

  In the seismic reinforcement method in which a strap is wound around an existing reinforced concrete column in a loop shape and tightened, a steel strap is selected as the strap, and the overlapping portion of the winding start end and winding end of the steel strap is connected to a handy type A seismic reinforcement method for reinforced concrete columns, which is solidified via seal fittings while tightening with a tool.   In the seismic strengthening method in which a strap is wound around an existing reinforced concrete column in a loop shape and tightened, a plastic band is selected as the strap, and the overlapping portion of the winding start end portion and the winding end portion of the plastic band is connected to a handy type Seismic reinforcement method for reinforced concrete columns, which is welded while tightening with a tool. 3. The method for seismic reinforcement of a reinforced concrete column according to claim 1 or 2, wherein, when the reinforced concrete column has a quadrangular cross section, the corner angle of the reinforced concrete column is chamfered in advance.

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