JP3839025B2 - PC steel bar connection structure and prestressed concrete structure - Google Patents

Description

  The present invention relates to a PC steel rod connection structure and a prestressed concrete structure.

  Currently, a concrete member reinforcement method called the bi-prestressing method is being implemented. That is, a PC steel material is arranged on the tensile side of the concrete member, and tensile stress is introduced into the PC steel material to fix it. A PC steel bar is disposed, and a compressive stress is introduced into the PC steel bar to be fixed, whereby tensile prestress is introduced into the concrete member for reinforcement.

  Regarding such a bipress stressing method, in Japanese Patent No. 1729000 (Patent Document 1), as a steel material for introducing a compression prestress into a concrete member, a steel material given a predetermined mechanical strength by heat treatment or stretching is used. There is described a bi-prestressing method characterized in that a steel bar to which a predetermined mechanical property is imparted by heat treatment is used as a steel bar to be used and to introduce tensile prestress. This Patent Document 1 intends to provide a high-quality bi-prestressing method by using a PC steel or a PC steel bar having a predetermined mechanical strength and mechanical properties.

  In addition to the above, Japanese Patent No. 1737472 (Patent Document 2) discloses a precast concrete block formed by dividing a plurality of precast concrete blocks side by side in series in the lateral direction and then placed on the sheath tube of the adjacent concrete block. A method of manufacturing a PC girder by connecting compressed PC steel rods inserted through a coupler and tensioning and fixing a tensile PC steel inserted through an adjacent concrete block, and then pressing and fixing the compressed PC steel rod. Is described. The coupler for connecting the compressed PC steel rods is accommodated in the large-diameter portion of the sheath tube, that is, in the coupler sheath, or accommodated in the concave portion for connecting the compressed steel rod formed at the end of the concrete block.

  FIG. 4 is a cross-sectional view of a conventional example. A pair of compressed PC steel bars 51 and 52 having a threaded connection end are screwed to a coupler 53 having a thread on the inner periphery. The coupler sheath 54 is accommodated in a coupler sheath 54 having a relatively large inner diameter, and throttle sheaths 55 are connected to both ends of the coupler sheath 54. In the case of forming a prestressed concrete member by on-site concrete, the compressed PC steel bars 51 and 52 connected in this way are arranged on the mold, and when the concrete is placed and solidified to a predetermined strength or more, Compressive stress is introduced and fixed in these compressed PC steel bars 51 and 52, grout material is injected from both ends of the sheath 55, and when the grout material comes out from the exhaust hole 56, the grout injection operation is stopped and prestressed concrete A member is formed.

Japanese Patent No. 1729000 Japanese Patent No. 1737472

  In the conventional examples of Patent Document 2 and FIG. 4, when the compression PC steel rod is pushed in and the compression force is introduced, the coupler portion moves slightly in the material axis direction, so the coupler sheath is not only in the radial direction but also in the material axis direction. Need to be as long as Therefore, the possibility that the coupler sheath interferes with the reinforcing bar increases, and there is a problem that the arrangement of the coupler sheath is restricted. Moreover, although the recessed part for compression steel rod connection formed in the edge part of the concrete block of patent document 2 does not have a problem in intensity | strength, generally a concrete structure wants to reduce a cross-sectional defect | deletion as much as possible. In addition, there is a problem that it is troublesome to install the formwork when manufacturing the concrete block.

  The present invention has been made in view of the above-described problems of the prior art, and the problem is that the possibility of interference between the PC steel rod insertion tube and the reinforcing bar at the joint portion between the compressed PC steel rods is reduced. It is an object of the present invention to provide a PC steel rod connection structure and a prestressed concrete structure capable of reducing cross-sectional defects for joining compressed PC steel rods as much as possible.

In order to solve the above problems, in the present invention, a plurality of PC steel rod connecting structures used for introducing tensile prestress on the compression side of a concrete member, each of which includes a plurality of PC steel rod insertion pipes. A plurality of PC steel rods are inserted into and connected to both ends of the thick short tube, and the PC steel rods are respectively inserted into the PC steel rod insertion tubes so that the end faces abut in the middle of the thick short tube. The space between the steel rod insertion tube and the short walled tube and the plurality of PC steel rods is filled with a rust preventive material, and when compressive stress is introduced into the plurality of PC steel rods, the end surfaces are brought into close contact with each other. A connection structure for PC steel rods to be joined is provided.
As described above, in the present invention, since the tips of the pressed PC steel rods are closely joined at the intermediate position of the short tube, the tip of the PC steel rod is inserted into the thick short tube. What is necessary is just to be formed in the inner diameter which can be moved, and it is not necessary to accommodate a coupler in a PC steel rod insertion tube like the prior art. Therefore, the tip joint portion of the PC steel rod, that is, the thick short tube, can be made smaller in outer diameter and length than the conventional coupler sheath. Further, the possibility of interference between the PC steel rod insertion tube or the short tube and the reinforcing bar can be reduced.

  Further, on the inner peripheral surface of the thick short tube, a screw thread is formed at a predetermined position on both ends, a smooth surface between the screw threads on both ends is formed with no irregularities, and the inner diameter of the PC steel rod insertion tube is The inner diameter of the thick short tube can be made substantially the same. With such a structure, both ends of the thick short tube can be screwed to the PC steel rod insertion tube, and the junction between the thick short tube and the PC steel rod insertion tube, the thick short tube, The device itself can be made smaller in inner diameter and outer diameter.

  In the present invention, a plurality of PC steel rod insertion tubes arranged on the compression side of the concrete member are inserted and connected to both ends of the thick short tube, and the plurality of PC steel rods are intermediate in the thick short tube. Inserted into the PC steel rod insertion tube so that the front end surfaces are in contact with each other, and a gap between the PC steel rod insertion tube and the walled short tube and the plurality of PC steel rods is filled with a rust preventive material. Then, compressive stress is introduced into the plurality of PC steel bars, the tip surfaces are brought into close contact with each other, and the plurality of PC steel bars are fixed to the concrete member, whereby tensile prestress is introduced to the concrete member compression side. A prestressed concrete structure is provided.

  In the present invention, since the tip ends of the PC steel rods are crimped and joined in the middle of the thick and short tube, there is no need to provide a compression steel rod connecting recess in the concrete member. Because the outer diameter and length can be made much smaller than the coupler sheath, it is possible to reduce the possibility of interference between the PC steel rod insertion tube or the walled short tube and the reinforcing bar at the joint between the PC steel rods. be able to.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 is a simplified cross-sectional view of a bi-prestressing concrete member.
In the bi-prestressing concrete member 1, for example, as shown in FIG. 1, the PC material insertion tube 2 is embedded on the tension side of the concrete member 1, and the tensile PC steel material 3 is inserted into the PC material insertion tube 2 and is tension-fixed. Thus, compression pre-stress is introduced, and the PC steel rod insertion pipes 6 and 7 through which the PC steel rods 4 and 5 are inserted are connected by the thick joint 8, and the PC steel rods 4 and 5 are pressed and fixed. Thus, tensile prestress is introduced, and the connection structure of the present invention is applied to the PC steel bar joint on the compression side.
Although FIG. 1 shows an example in which two PC steel rods 4 and 5 and two PC steel rod insertion pipes 6 and 7 are connected, an example applied to a bridge girder will be described. PC steel bars are generally about 8m at the longest for transportation reasons. When constructing a span of about 40m, four 8m PC steel bars and one short PC steel bar Need to be connected and used. Therefore, the PC steel bars are connected at four locations, and the connection structure of the present invention can be applied at each of these connection locations.

FIGS. 2A and 2B are enlarged cross-sectional views before and after joining the PC steel bars.
PC steel rods 4 and 5 are inserted into the PC steel rod insertion tubes 6 and 7 whose rust preventive material has been applied to the inner peripheral surface in advance, respectively. A screw thread is formed. These PC steel rod insertion pipes 6 and 7 are inserted into both ends of the thick short tube 8 and screwed together, and the PC steel rods 4 and 5 are in contact with each other at the end in the middle of the thick short tube 8. When compressive stress is introduced into the steel rods 4 and 5 and fixed to the concrete member, the tip surfaces of the PC steel rods 4 and 5 are pressed together and joined together.

  FIG. 3 is a cross-sectional view of the thick short tube 8. The walled short tube 8 is one in which the end surfaces of the PC steel rods 4 and 5 are brought into contact with each other to introduce a compressive stress, so that the PC steel can be restrained from lateral deformation. It is made of a metal material such as steel or stainless steel slightly thicker than the rod insertion tubes 6 and 7. The thick short tube 8 is formed with a smooth surface having no threads on the inner peripheral portion 8a at both ends, and a thread is formed on the inner peripheral portion 8b inside the screw thread portion 8a. The screw thread portions 8b The inner peripheral surface of the section 8c sandwiched between the surfaces is formed as a smooth surface without unevenness. Further, the inner diameter of the section 8c of the thick short tube 8 and the inner diameter of the PC steel rod insertion tubes 6 and 7 are set so that the clearance between the PC steel rods 4 and 5 inserted therein is about 1 to 2 mm. Is done. When the PC steel rod insertion tubes 6 and 7 are screwed here, the threaded portion 8b is flush with the inner peripheral surface of the PC steel rod insertion tubes 6 and 7 and the inner peripheral surface of the section 8c. The dimensions are set so that there is no step.

  Therefore, in the connection structure of the PC steel rods of the present invention, it is not necessary to screw these conventional compression steel bars 4 and 5 with conventional threaded couplers to join both ends. A coupler sheath for housing the coupler is no longer necessary. Therefore, the tip joints of the PC steel bars 4 and 5, that is, the walled short tube 8, which has a smaller outer diameter and length than the conventional coupler sheath, can be used and can interfere with the reinforcing bar. The property is also suppressed to a very small one.

Next, the prestressed concrete structure to which the connecting structure of the PC steel bar of the present invention is applied will be described.
For example, when building a prestressed concrete structure such as a bridge girder in the spot-on-site concrete, a unit in which a PC steel bar is inserted into a PC steel bar insertion tube whose rust preventive material has been applied to the inner peripheral surface in advance is used. They are brought into the construction site, and these units are connected on the formwork by connecting them with a thick short tube at the construction site. After placing other materials, that is, PC steel material insertion tube, tensile PC steel material, rebar, etc. on the formwork as necessary, the concrete is placed on the formwork and the concrete is solidified to a predetermined strength or more. Compressive stress is introduced into the steel bar. If the PC steel bar is fixed to the concrete member, the tip surfaces of the PC steel bars are pressure-bonded and joined together, and tensile pre-stress is introduced to the compression side of the concrete member to construct a pre-stressed concrete structure. It should be noted that a tensile stress is introduced and fixed to the PC steel material disposed on the tensile side of the concrete member at an appropriate timing, and a compressive prestress is introduced to the tensile side of the concrete member.

It is a simple sectional view of a concrete member to which the present invention is applied. (A) (b) is an expanded sectional view before and behind joining of a PC steel rod. It is sectional drawing of a thickness short tube. It is sectional drawing which shows a prior art example.

Explanation of symbols

1 Concrete member 4 PC steel bar 5 PC steel bar 6 PC steel bar insertion pipe 7 PC steel bar insertion pipe 8 Thickness short pipe

Claims (3)

  A connection structure of a plurality of PC steel rods used to introduce tensile prestress on the compression side of a concrete member, and a plurality of PC steel rod insertion tubes are respectively inserted and connected to both ends of a thick short tube. The plurality of PC steel bars are respectively inserted into the PC steel bar insertion pipes so that the tip surfaces thereof are in contact with each other in the middle of the thin walled short pipe, and the PC steel bar insertion pipe, the thick short pipe, and the Connection of PC steel rods, in which gaps between the plurality of PC steel rods are filled with a rust preventive material, and when the compressive stress is introduced into the plurality of PC steel rods, the end surfaces are closely bonded to each other. Construction.   On the inner peripheral surface of the thick short pipe, screw threads are formed at predetermined positions on both ends, and between the screw threads on both ends are formed on a smooth surface without irregularities, and the inner diameter of the PC steel rod insertion pipe is: 2. The connection structure of PC steel rods according to claim 1, wherein the connection structure is substantially the same as the inner diameter of the thick short pipe.   A plurality of PC steel rod insertion tubes arranged on the compression side of the concrete member are inserted and connected to both ends of the thick short tube, and the plurality of PC steel rods have their end surfaces in the middle of the thick short tube. Each of the PC steel rod insertion pipes is inserted into the PC steel rod insertion pipes so as to come into contact with each other, and gaps between the PC steel bar insertion pipes and the walled short pipes and the plurality of PC steel bars are filled with a rust preventive material. Prestressed in which tensile prestress is introduced on the concrete member compression side by introducing compressive stress to the PC steel rods, bringing the end surfaces into close contact, and fixing the plurality of PC steel rods to the concrete member Concrete structure.

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