JP4866489B1 - Fixing tool - Google Patents

Abstract

PROBLEM TO BE SOLVED To prevent rust of a fixing device without applying a rust preventive paint.
A fixing device (101) that prestresses a concrete frame using a restoring force of a tension material (94) and is covered with post-cast concrete, and is a sleeve ( 92), the bearing plate (2) through which the tendon penetrates, receives the restoring force from the sleeve and transmits it to the concrete frame, and all the exposure of the sleeve and bearing plate attached to the sleeve and before the concrete is beaten A cap (1) covering the surface.
[Selection] Figure 2

Description

  The present invention relates to a technique for prestressing a concrete frame using a tendon.

  There are known a prestressed concrete (hereinafter referred to as PC) and a PC construction method in which a steel material is disposed from one end to the other end of a concrete frame and the steel material is tensioned to give a compressive force to the entire frame.

  Here, with reference to FIG. 8 and FIG. 9, the configuration of the conventional PC steel fixing member will be described. FIG. 8 is a diagram showing a configuration of a conventional fixing tool and PC steel material, and FIG. 9 is a schematic diagram showing a cross section (A, B) of the conventional fixing tool.

  A bearing plate 91 is fixed to one end of the sheath 90 that protects the PC steel 94, which is a tension material. A sleeve 92 is disposed on the surface of the support plate 91 opposite to the contact surface with the sheath 90. The sleeve 92 has a groove 92a into which the wedge 93 is inserted.

  The wedge 93 has a groove portion 93a through which the PC steel material 94 passes. Here, the PC steel material 94 can be fixed by inserting the wedge 93 in which the PC steel material 94 is inserted into the groove portion 93 a into the groove portion 92 a of the sleeve 92. Then, by compressing the PC steel material 94, a compressive force can be applied to the prestressed concrete 95 (concrete frame) via the bearing plate 91.

  The bearing plate 91 has a function for imparting the tension of the PC steel 94 (the restoring force of the PC steel 94) to the concrete 95. Further, the bearing plate 91 has a through hole 91a for allowing the PC steel material 94 to pass therethrough, and a centering spacer 96 is provided at one end of the through hole 91a (an end in contact with the concrete 95). The centering spacer 96 has a through hole 96 a for allowing the PC steel material 94 to pass therethrough, and the inner peripheral surface of the through hole 96 a is in contact with the outer peripheral surface of the PC steel material 94.

  After the tension of the PC steel material, the extra length of the PC steel material is cut, and the cap 80 is attached to the fixing tool. Further, the following documents are disclosed as related techniques.

Japanese Patent No. 3791415 Japanese Patent No. 3912297

  During the period from the completion of the tension of the PC steel material to the placement of ground-covering concrete or post-cast concrete, the state is as shown in at least FIGS. In this state, a part of the sleeve 92 (the part where the cap 80 is not covered) and the pressure bearing plate 91 are exposed to the outside. Therefore, an operation of applying a rust preventive paint to prevent rust of the exposed part is performed. appear. This coating operation becomes complicated as the number of fixing devices is increased.

  The present embodiment is made in order to solve the above-described problems, and aims to provide a technique that contributes to reduction of global environmental load while reducing labor.

A first aspect of the present invention is the gun, a fixing device prestressing the concrete skeleton using a restoring force of tendon, a sleeve is fixed to the end of the tension member, the tension member penetrates, the restoring force A bearing plate that receives from a sleeve and transmits it to the concrete frame , one surface of which forms the same surface as the end surface of the concrete frame and has an exposed region, and is attached to the sleeve. And a cap covering all exposed areas of the platen. The cap has a protrusion that protrudes from the inner wall surface facing the sleeve and contacts the outer peripheral surface of the sleeve.
A second invention of the present application is a fixing device that prestresses a concrete frame using a restoring force of a tendon, and a sleeve fixed to an end of the tendon, a tendon penetrates, and the restoring force is transferred to the sleeve. Bearing plate that receives from and transmits to the concrete frame, one surface of which forms the same surface as the end surface of the concrete frame and has an exposed region, and is attached to the sleeve, the sleeve and the bearing plate And a cap that covers all the exposed areas. The inner wall surface of the cap abuts against the outer peripheral surface of the sleeve while generating frictional resistance.

  The bearing plate can be provided with an inclined surface facing the sleeve. Specifically, a tapered surface whose diameter continuously increases as the distance from the sleeve along the tendon can be formed on the bearing plate. Thereby, the bearing plate can efficiently transmit the force received from the sleeve to the concrete frame.

  The bearing plate can be provided with a cylindrical portion that contacts the sleeve at the end face. By providing the cylindrical portion, the thickness of the concrete covering the bearing plate can be ensured in a state before the concrete is post-placed. Here, cylindrical portions having different diameters can be provided at both ends of the bearing plate in the direction in which the tendon extends.

  Recycled material can be used as the cap material. A filler can be filled between the cap and the sleeve. By using the filler, the rust prevention of the sleeve and the like can be improved. Providing a protrusion protruding from the inner wall surface of the cap facing the sleeve makes it easier to fill the filler.

  The protrusion can be extended in the direction in which the tendon material extends. Here, the protrusion amount of the protrusion from the inner wall surface of the cap can be reduced toward the insertion opening of the cap with respect to the sleeve. Accordingly, the cap can be easily attached to the sleeve, and the cap can be easily fixed to the sleeve. The tendon can be composed of one PC steel strand.

  Rust prevention of the fixing device can be achieved without applying antirust paint.

It is a perspective view which shows an example of the fixing tool of embodiment. It is sectional drawing which shows an example of a structure when the fixing tool of embodiment is installed in a concrete frame. It is a figure which shows an example of load distribution when using the fixing tool of embodiment. It is a figure which shows the shape of the conventional bearing plate, and the shape example of the bearing plate of embodiment. It is a figure which shows the example of a variation of the fixing tool of embodiment. It is a figure which shows the example which is filled with the filler in the space | gap part of the fixing tool of embodiment. It is an external appearance schematic diagram which shows an example when the aspect of embodiment is applied to a bridge. It is a figure which shows a structure when the conventional fixing tool is installed in a concrete frame. It is a figure which shows the cross section of the conventional fixing tool.

  FIG. 1 is an external perspective view showing an example of a fixing tool of the present embodiment, and FIG. 2 is a view showing an example of a state in which the fixing tool and PC steel material of the present embodiment are installed in a concrete frame. The fixing tool 101 includes a cap 1 and a pressure plate 2. The configuration of the fixing device 101 is the same as the conventional one except for the matters described below.

  The cap 1 is made of a synthetic resin such as polyethylene, and a recycled material (resin) can also be used. When the recycled material is used, the usage rate of the recycled material can be, for example, about 30%, but the usage rate can be set as appropriate. In the present embodiment, as a material for the centering spacer 96, a synthetic resin can be used, and a recycled material (resin) can also be used.

  The cap 1 has a shape that covers the entire surface of the sleeve 92, the wedge 93, and the PC steel material (for example, PC steel strand) 94 shown in FIG. Yes. The cap 1 is formed in a shape along the ends of the sleeve 92, the wedge 93 and the PC steel material 94. The cap 1 has a flange 1a. The flange 1 a protrudes from the outer peripheral surface of the cap 1 toward the outside of the cap 1.

  The bearing plate 2 is made of a hard material such as steel or iron, and has a truncated cone portion 2B having a truncated cone shape. The bearing plate 2 is embedded so that the side with the smaller diameter of the truncated cone part 2B becomes the surface side of the concrete 95 and the side with the larger diameter of the truncated cone part 2B becomes the inner side of the concrete 95, 2B is installed so as not to be exposed to the outside (see FIG. 2). The inclined surface of the truncated cone part 2B faces the sleeve 92 side (left side in FIG. 2).

  The bearing plate 2 has a cylindrical portion 2A and a cylindrical portion 2C. The cylindrical portion 2A is formed integrally with the smaller diameter side of the truncated cone portion 2B, and the thickness of the cylindrical portion 2A (the length in the left-right direction in FIG. 2) is the thickness of the truncated cone portion 2B (see FIG. 2 in the horizontal direction). The cylindrical part 2C is formed integrally with the larger diameter side of the truncated cone part 2B, and the thickness of the cylindrical part 2C (the length in the left-right direction in FIG. 2) is thinner than the thickness of the truncated cone part 2B. .

In this embodiment, the distal end surface of the cylindrical portion 2A is almost no (flush with) the surface and the step of concrete 95 Ru der.

  Here, the advantage of the configuration having the cylindrical portion 2A will be described. In the bearing plate 2 of the present embodiment, the cylindrical portion 2A is provided on the surface side of the concrete 95 with respect to the truncated cone portion 2B. Here, for example, when the cylindrical portion 2A is omitted and the small-diameter portion of the truncated cone portion 2B and the surface of the concrete 95 are in a flush state, the truncated cone is directed from the surface of the concrete 95 toward the inside of the concrete 95. The slope of the part 2B will extend.

  In this case, since the angle formed by the surface of the concrete 95 and the slope of the truncated cone part 2B is an acute angle, the concrete thickness between the bearing plate 2 (the slope of the truncated cone part 2B) and the surface of the concrete 95 becomes thin, There is a possibility that the concrete provided along the slope of the truncated cone part 2B may be peeled off. In order to prevent this peeling, the bearing plate 2 of the present embodiment is provided with a cylindrical portion 2A in the vicinity of the surface of the concrete 95 so that the angle formed between the side wall surface of the cylindrical portion 2A and the surface of the concrete 95 is substantially vertical. Be placed. On the other hand, when the cylindrical portion 2C is provided, the support plate 2 can be easily formed when the support plate 2 is formed using a mold. The cylindrical portion 2C can be omitted.

  The fixing device 101 having the cap 1 and the pressure plate 2 eliminates the exposed portions of the sleeve 92, the wedge 93, and the PC steel material 94, and can prevent rust during construction. Therefore, no coating for rust prevention is required, and labor saving at the site can be achieved.

  Next, the shape of the bearing plate 2 will be further described with reference to an example of the load distribution in FIG. As shown in FIG. 3, the bearing plate 2 transmits the load received from the sleeve 92 to the concrete 95. The direction of the load P1 applied to the contact surface of the bearing plate 2 and the sleeve 92 is the axial direction of the PC steel material 94 (left-right direction in FIG. 3). Also, the load P2 acting on the concrete 95 needs to be in the same direction as the load P1. The shape of the bearing plate 2 can be determined in consideration of the distribution when changing from the load P1 to the load P2.

  In the present embodiment, as described above, the bearing plate 2 has the truncated cone part 2B. The truncated cone part 2B is formed in a shape along the load transmission path when the load P1 changes to the load P2. Here, the truncated cone part 2B has the slope described above. Further, the region where the load P2 acts is larger than the region where the load P1 acts. Therefore, the load transmission path is a path along the outer shape of the truncated cone part 2B, and the load can be efficiently applied to the concrete 95 using the truncated cone part 2B.

  FIG. 4 is a plan view of a conventional bearing plate 91 (see FIGS. 4A and 4B) and the bearing plate 2 of this embodiment (see FIG. 4C), and a center line AA. Cross-sectional views are shown respectively. As shown in the plan views of FIGS. 4A and 4B, the conventional bearing plate 91 has a quadrangular planar shape. However, when a load is applied, the load applied to the corner portions of each quadrangular shape. Becomes minute. Therefore, as shown in the plan view of FIG. 4C, the pressure bearing plate 2 of the present embodiment is a circular shape with the corners removed, and a frustoconical shape for the reason described with reference to FIG. .

  The example of FIG. 4C has a shape in which the corners of the square shown in FIG. 4A are removed. With this, for example, the weight can be reduced from about 6.4 kg to about 3.0 kg. As shown in FIG. 4C, in the present embodiment, the planar shape of the bearing plate 2 is a substantially perfect circle (since the skirt of a part of the cylindrical portion 2C is a straight line, it is not strictly a perfect circle). However, it may be an ellipse based on a rectangle as shown in FIG. Moreover, the dimension and weight described in FIG. 4 are merely examples, and do not limit the aspect.

By using such a shape, the amount of material used can be reduced, and CO ₂ emission can be reduced when the bearing plate 2 is manufactured.

  Next, the shape of the cap of this embodiment will be described. FIG. 5A shows the shape of a conventional cap 80, and FIGS. 5B and 5C show examples of the cap of this embodiment.

  In the conventional cap 80, as shown in FIG. 5A, a part of the sleeve 92 and the pressure bearing plate 91 are exposed to the outside air. Therefore, it is necessary to apply a rust preventive paint to the exposed portion. The cap of the present embodiment is shaped to cover the sleeve 92, the wedge 93, and the entire outermost portion of the PC steel material 94 as in the cap 1A shown in FIG. 5B, and the bearing plate 2 is embedded in the concrete 95. Therefore, the steel material is not exposed and no coating for rust prevention is required.

  In FIG. 5B, one end surface of the sleeve 92 is in contact with the distal end surface of the cylindrical portion 2 </ b> A in the bearing plate 2. In the contact portion between the sleeve 92 and the cylindrical portion 2 </ b> A, the diameter of the cylindrical portion 2 </ b> A is larger than the diameter of the sleeve 92. The flange 1a of the cap 1A is in contact with a region (a part of the cylindrical portion 2A) located outside the sleeve 92 in the cylindrical portion 2A, and covers this region. In the present embodiment, the flange 1a is provided on the cap 1A, but the flange 1a may be omitted. When the flange 1a is omitted, the cap 1A only needs to cover the area of the cylindrical portion 2A that protrudes from the sleeve 92.

  In the shape of FIG. 5B, the area of the abutting portion 11a between the outer wall surface of the sleeve 92 and the inner wall surface of the cap 1A is increased. It may be difficult to put on. Therefore, the shape of the cap may be as shown in FIG. In the cap 1 </ b> B shown in FIG. 5C, ribs 5 (projections) are partially provided at a plurality of locations on the inner wall surface to make it easy to cover the sleeve 92. When the rib 5 is provided, deformation of the sleeve 92 (for example, temperature change, swelling during use, product manufacturing error, etc.) can be absorbed by deformation of the rib 5, and the cap 1B can be easily fixed to the sleeve 92. The cap 1B can be prevented from falling off.

  The rib 5 protrudes inward from the inner wall surface of the cap 1B, and the protruding amount of the rib 5 becomes shorter toward the opening of the cap 1B. That is, the protrusion amount T1 is shorter than the protrusion amount T2. The rib 5 does not extend to the opening of the cap 1B. Since the diameter of the opening of the cap 1B is larger than the diameter of the sleeve 92 and the rib 5 is not formed in the opening of the cap 1B, the cap 1B can be easily attached to the sleeve 92.

  When the cap 1 </ b> B is inserted along the sleeve 92, the tips of the ribs 5 come into contact with the outer wall surface of the sleeve 92. When the cap 1B is pushed in a state in which the tip of the rib 5 is in contact with the outer wall surface of the sleeve 92, the cap 1B can be fixed to the sleeve 92 by bringing the tip of the rib 5 into close contact with the outer wall surface of the sleeve 92. As described above, the protruding amount of the rib 5 increases as the distance from the opening of the cap 1B increases. Therefore, as the cap 1B is pushed into the sleeve 92, the rib 5 easily comes into close contact with the outer wall surface of the sleeve 92. Since the rib 5 is formed of resin, the rib 5 can be deformed according to the outer shape of the sleeve 92.

  In the present embodiment, the rib 5 is provided at the position shown in FIG. 5C on the inner wall surface of the cap 1B. However, the position where the rib 5 is provided and the number of the ribs 5 can be appropriately set. In this embodiment, as shown in FIG. 5C, the ribs 5 extend in the direction in which the PC steel material 94 extends, but the present invention is not limited to this. That is, what is necessary is just to protrude toward the inner side from the inner wall face of the cap 1B.

  FIG. 6 shows another embodiment, and shows an example in which a resin is filled in the cap of this embodiment. FIG. 6A shows an example in which the filler 6 is filled into the cap 1A shown in FIG. 5B. As the filler 6, for example, an acrylic or epoxy resin can be used. Thus, the effect of rust prevention improves by using the filler 6. FIG. Further, when a resin is applied to PC steel such as afterbond PC steel, the fluidity of the applied resin is high in the initial stage. By using the filler 6, it is possible to prevent the resin applied to the PC steel material from dripping.

  FIG. 6B shows an example in which the filler 6 is filled into the cap 1B shown in FIG. When the cap 1A is used, as shown in FIG. 6A, since the inner wall surface of the cap 1A and the outer wall surface of the sleeve 92 are in close contact with each other, it is difficult to form a gap. Therefore, it is difficult for the filler 6 to reach around the sleeve 92. When the cap 1B is used, the rib 5 is provided as shown in FIG. 6B, and a gap is formed between the inner wall surface (the surface excluding the rib 5) of the cap 1B and the sleeve 92, so that the filler 6 can be used. When filled, the filler 6 enters the gap, and the rust prevention effect is enhanced.

  As a method of filling the filler 6 inside the caps 1A and 1B, for example, before the caps 1A and 1B are attached to the sleeve 92, the filler 6 is stored in the caps 1A and 1B. When the caps 1A and 1B are pushed into the sleeve 92, the filler 6 can be positioned on the outer periphery of the sleeve 92.

  Finally, an example will be described in which the aspect of the present embodiment is applied to a bridge lateral fastening cable that is a prestressed concrete structure. FIG. 7 is a schematic external view of a bridge 100 to which the embodiment of the present embodiment is applied. The state shown in FIG. 7 shows a state before the fixing tool 101 is covered with post-cast concrete. In the bridge girder width direction (X-axis direction), a plurality of PC steel materials are installed from one end of the bridge girder to the other end. The fixing tool 101 of this embodiment is attached to both ends of each PC steel material, and compressive force is given to the bridge inner side and the bridge girder width direction by the tension of the PC steel material (the restoring force of the PC steel material).

  As described above, in this embodiment, it can be applied to a single strand (one tension material), and a compressive force can be applied to the concrete frame. In the state shown in FIG. 7, the fixing tool 101 is covered with post-cast concrete. In the structure shown in FIG. 7, the PC steel material is arranged along the bridge girder width direction, and the fixing tool 101 is arranged at both ends of the PC steel material. However, the present invention is not limited to this. That is, the fixing device of the present invention can be used as long as it is a structure that applies prestress to concrete. For example, when a PC steel material is disposed along the longitudinal direction of the bridge (Y direction in FIG. 7), fixing tools can be disposed at both ends of the PC steel material. In addition, the fixing tool of the present invention can be used when prestress is introduced into a building beam.

  In the present embodiment, the support plate 2 embedded in the concrete 95 is used, but the present invention is not limited to this. Specifically, the support plate 91 described with reference to FIGS. 4A and 4B can be used. In this case, the bearing plate 91 is disposed on the outer surface of the concrete 95, but the bearing plate 91 may be covered with the cap 1.

  The “conical frustum” conceptually includes a truncated cone constituted by a perfect circle on both the upper surface and the lower surface, and an elliptic frustum in which either one or both of the upper surface and the lower surface is an ellipse.

  As described above, by applying the aspect of this embodiment, it is possible to save labor and to obtain the effect of rust prevention without applying the rust preventive paint. In addition, the use of recycled materials for caps and centering spacers, and the removal of parts that do not affect load distribution, such as making the bearing plate from a cube in the shape of a truncated cone, contributes to reducing the burden on the global environment. can do.

1, 1A, 1B: Cap 2: Bearing plate 2A, 2C: Cylindrical portion 2B of bearing plate 5: Frustum portion of bearing plate 5: Rib 6: Filler 90: Sheath 92: Sleeve 93: Wedge 94: PC steel 95: Concrete 96: Centering spacer 100: Bridge

Claims (7)

Using a restoring force of the tension member to a fixing device for prestressing the concrete skeleton,
A sleeve fixed to an end of the tendon;
The tension material penetrates and receives the restoring force from the sleeve and transmits it to the concrete frame , and one surface forms the same surface as the end surface of the concrete frame, and an exposed region A bearing plate with
A cap attached to the sleeve and covering all exposed areas of the sleeve and the bearing plate ;
The fixing device according to claim 1, wherein the cap has a protruding portion that protrudes from an inner wall surface facing the sleeve and contacts the outer peripheral surface of the sleeve . The fixing device according to claim 1 ,
The protrusion extends in the direction in which the tendon extends ,
The fixing tool according to claim 1, wherein a protruding amount of the protruding portion from the inner wall surface decreases toward an insertion port of the cap into which the sleeve is inserted . A fixing tool that prestresses a concrete frame using the restoring force of a tendon,
A sleeve fixed to an end of the tendon;
The tension material penetrates and receives the restoring force from the sleeve and transmits it to the concrete frame, and one surface forms the same surface as the end surface of the concrete frame, and an exposed region A bearing plate with
A cap attached to the sleeve and covering all exposed areas of the sleeve and the bearing plate;
The fixing device according to claim 1 , wherein an inner wall surface of the cap abuts against an outer peripheral surface of the sleeve while generating a frictional resistance . The fixing device according to any one of claims 1 to 3 ,
The bearing capacity plate, Ru is disposed inside the front Symbol concrete skeleton, fixing device characterized by having an inclined surface facing the side of the sleeve. The fixing device according to claim 4 ,
The fixing member according to claim 1, wherein the support plate has cylindrical portions having different diameters at both ends in a direction in which the tendon extends. The fixing device according to any one of claims 1 to 5 ,
The cap is made of a recycled material as a material. The fixing device according to any one of claims 1 to 6 ,
A fixing device having a filler filled between the cap and the sleeve.

Images