JP3771997B2 - PC fixing device and PC fixing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a PC fixing device and a PC fixing method used in a post tension system.
[0002]
[Prior art]
Prestressed concrete is broadly divided into pre-tension and post-tension methods depending on the prestress introduction time. In post-tension method, the tension material can be freely placed in the concrete. It is possible to easily introduce a large prestress into cast-in-place concrete and has a wider application range than the pretension method.
[0003]
Tensile material fixing tools used in such post-tension systems include those that fix a PC steel material, which is a tension material, with a wedge (Frecine method, VSL method, single-strand method, etc.), and thread rolling at the end of the PC steel material. PC nuts that are fixed by nuts, those that are made by fixing the head to the end of the PC steel (BBRV method), and sleeves that are crimped to the outer side of the PC steel by cold working, etc. There are those that are fixed by supporting pressure on the side end face (SEEE method).
[0004]
[Problems to be solved by the invention]
On the other hand, recently, there has been an increasing number of cases in which FRP materials (fiber reinforced plastic materials) using carbon fibers, aramid fibers or the like instead of PC steel materials are used as tension materials. Since such FRP material is lightweight and has good workability and can avoid damage caused by salt, it is gradually being adopted for PC bridges in the bay area.
[0005]
However, since the FRP tendon is generally formed into a flat band for the purpose of improving the tensile strength, the fixing tool for fixing the PC steel having a circular cross section is used as the FRP tendon as it is. It cannot be diverted.
[0006]
In particular, it is necessary to increase the number of FRP tendons in order to introduce a large prestress in response to an increase in the size and length of the structure. Fixtures that can be carried out have not been developed yet, and it has been necessary to carry out tension fixing work one by one in the field. For this reason, such tension and fixing work take time, and there is a problem that tension may vary.
[0007]
The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a PC fixing tool and a PC fixing method capable of performing tension and fixing on a plurality of FRP tendons collectively. To do.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a PC fixing device according to the present invention comprises, as described in claim 1, a bearing plate attached near the surface of a concrete frame, and a tension material insertion hole configured to be freely fitted into the bearing plate. A plurality of radially-shaped cylindrical fixing blocks, an annular lock nut that is screwed into the outer peripheral surface of the fixing block and locks the fixing block to the bearing plate, and a tension material insertion hole. The fixing block is formed with a plurality of wedges inserted so as to sandwich the material, and a female screw to which a predetermined tension rod is detachably screwed is formed in an area surrounded by the tension material insertion hole. And a pair of opposing inner surfaces formed in a taper shape with the cross-section of the tendon insertion hole being a square hole, and the wedge on one side for the tendon A pair of wedge members formed in a taper shape so as to be in contact with the taper inner surface of the through-hole and the other surface being a contact surface with the belt-like tension member, and the pair of wedge members constitute the belt-like shape. It is constructed so as to sandwich a tendon.
[0010]
In the PC fixing device of the present invention, a protrusion that contacts the end of the wedge inserted into the tension material insertion hole is formed on the back surface, and a bolt hole for attachment to the fixing block is formed. It is equipped with a holding plate.
[0011]
According to the PC fixing method of the present invention, as described in claim 3, a tension material is inserted through a plurality of tension material insertion holes formed radially in a cylindrical fixing block, and the fixing block is placed on the surface of the concrete frame. The tension member is fitted in a bearing plate attached in the vicinity and is locked to the bearing plate by an annular lock nut screwed into the outer peripheral surface of the fixing block so that the tension material is sandwiched in each of the tension material insertion holes. While inserting a wedge, a predetermined tension rod is screwed onto a female screw formed in the fixing block region surrounded by the tension material insertion hole, and the tension rod is pulled while taking a reaction force from the bearing plate. By applying force, tension force is introduced into the tension member, and the lock nut is turned to eliminate the gap formed between the tension plate and the tension rod. A PC fixing method for releasing the force to transmit the tension force of the tendon to the support plate and detaching the tension rod, the cross section of the tendon insertion hole being a square hole and a pair of opposing inner surfaces The wedge is formed in a tapered shape so that one surface is in contact with the tapered inner surface of the tension material insertion hole, and the other surface is a contact surface with the belt-shaped tension material. And a pair of wedge members, and the belt-like tension member is sandwiched between the pair of wedge members.
[0012]
In the PC fixing device and the PC fixing method of the present invention, since a female screw to which a tension rod is screwed is formed on the fixing block, a tension material is inserted into a plurality of tension material insertion holes arranged radially around the female screw. If the tension rod is screwed onto the above-mentioned female screw and a tensile force is applied to the rod, the tensile force of the rod is applied to a plurality of tensions via the fixing block and the wedge. The tension is transmitted to the material, and a predetermined tension force is introduced almost uniformly into each tension material.
[0013]
The number of tendon insertion holes is not limited as long as it is plural.
[0014]
The tension material insertion hole and the wedge may be appropriately selected according to the cross-sectional shape and type of the tension material to be used. For example, if a PC steel material having a circular cross section is used as the tension material, the tension material insertion hole is provided. It is sufficient to use a wedge member which is divided into several parts and has a conical inner surface and a conical outer surface corresponding to the conical inner surface. The pair is formed in a taper shape, and the wedge is formed in a taper shape so that one surface is in contact with the taper inner surface of the insertion hole for the tension material, and the other surface is a contact surface with the belt-like tension material. A pair of wedge members, and when the belt-like tension members are sandwiched between the pair of wedge members, it is possible to collectively tension a plurality of FRP tension members formed in a belt shape. Become.
[0015]
As FRP tendons, all fiber reinforced plastic tendons are included. Specifically, carbon fibers, aramid fibers, glass fibers, silicon carbide fibers, etc. are used as the reinforcing fibers, and epoxy is used as the plastic. Examples include, but are not limited to, tendons with combinations of resins, vinyl ester resins, phenolic resins, unsaturated polyester resins, and the like.
[0016]
When fixing the wedge inserted into the tension material insertion hole, it may be driven into the hole one by one with a hammer or the like as before, but a pressing plate with protrusions on the back is stacked on the fixing block. If the protrusions are in contact with the ends of the wedges, and the bolts are screwed into the fixing block through the mounting bolt holes formed in the pressing plate in this state, the wedges are tensioned simultaneously and evenly by the pressing plate protrusions. It can be pushed into the material insertion hole.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a PC fixing tool and a PC fixing method according to the present invention will be described below with reference to the accompanying drawings.
[0018]
FIG. 1 is a cross-sectional view showing a PC fixing device according to the present embodiment. As can be seen from the figure, the PC fixing device 1 of the present embodiment includes a support plate 3, a fixing block 4 configured to be freely fitted in the support plate, and a fixing block screwed into the outer peripheral surface of the fixing block. Is generally composed of an annular lock nut 5 for engaging the support plate 3 and a wedge 7 for fixing the FRP tension material 6 as the tension material to the fixing block 4.
[0019]
The bearing plate 3 is embedded in the surface of the concrete housing 2 and transmits the tension force of the FRP tendon 6 to the concrete housing 2 as a prestress, and the sheath 8 disposed in the concrete housing. Connected to the end.
[0020]
The fixing block 4 has a cylindrical shape as a whole as can be seen from the front view of FIG. 2 (a), and has a female screw 9 perforated at its center to which a tension rod described later is detachably screwed. A male screw 11 for screwing the lock nut 5 is formed on the outer peripheral surface.
[0021]
Further, the fixing block 4 is formed with six tension material insertion holes 21 so as to surround the female screw 9, and the tension material insertion holes have a square hole-like cross section as can be seen in FIG. The opposed inner surfaces 22, 22 are tapered.
[0022]
As shown in FIG. 2, the fixing block 4 is provided with a bolt hole 12 for attaching a pressing plate, which will be described later.
[0023]
On the other hand, as shown in FIG. 3, the wedge 7 is composed of a pair of wedge members 31, 31, each wedge member 31 having a tapered surface 32 that comes into contact with the tapered inner surface 22 of the tension material insertion hole 21, and A tension material abutment surface 33 that is a contact surface with the FRP tension material 6 having a belt-like cross section, and the belt-like FRP tension material 6 is sandwiched between the tension material abutment surfaces 33 facing each other. Yes.
[0024]
As shown in FIG. 4, the lock nut 5 has a female screw 41 formed on the inner surface thereof, and is screwed with a male screw 11 formed on the outer peripheral surface of the fixing block 4.
[0025]
In order to perform tension of the FRP tendon 6 and fixing to the concrete frame 2 using the PC fixing tool 1 of the present embodiment, the sheath 8 is arranged in the concrete placing area in advance of the PC construction and a formwork (not shown). The bearing plate 3 is attached to the inner surface, and concrete is placed in such a state. Then, the concrete is cured for a predetermined period.
[0026]
Next, when a predetermined concrete strength is developed, the FRP tendon 6 is inserted through the sheath 8. Then, as shown in FIG. 5, the end of the tension member is inserted into the tension member insertion hole 21 of the fixing block 4, and the lock nut 5 is screwed into the outer peripheral surface of the block. The block is fitted into the bearing plate 3 as shown by the arrow in FIG.
[0027]
Next, as shown in FIG. 6, the wedge members 31, 31 are inserted so that the FRP tendon 6 is sandwiched between the tendon insertion holes 21 of the fixing block 4.
[0028]
Next, a pressing plate 51 is attached to the front side of the fixing block 4. As can be clearly seen in FIG. 7, the presser plate 51 is configured by an annular disk in which a rod hole 52 through which a tension rod, which will be described later, is passed, is formed in the center, and corresponds to the tension material insertion hole 21 of the fixing block 4. A slit 53 for allowing the FRP tendon 6 passed through the insertion hole to pass therethrough is formed at the location, and protrusions 54 are formed on the back sides of both sides thereof. The wedge members 31, 31 that are sandwiched are brought into contact with the end portions of the wedge members 31, 31 so as to be pushed into the depth of the tension material insertion hole 21.
[0029]
In addition, the holding plate 51 is provided with mounting bolt holes 55 at positions corresponding to the bolt holes 12 provided in the fixing block 4, and bolts are passed through the mounting bolt holes to the bolt holes 12 of the fixing block 4. It can be screwed in.
[0030]
In order to push the wedge members 31, 31 into the back of the strainer insertion hole 21 using the presser plate 51, as shown in FIG. 6, the protrusion 54 formed on the back surface of the presser plate 51 has a tensioner insertion hole. The wedge member 31 inserted in the position 21 is positioned so as to abut against the end of the wedge member 31. At this time, it passes through the slit 53 of the pressing plate 51 so that the FRP tendon 6 does not get in the way. Next, a bolt (not shown) is screwed into the bolt hole 12 of the fixing block 4 through the mounting bolt hole 55 of the holding plate 51. Bolts should be screwed evenly at 6 locations.
[0031]
In this way, the pressing plate 51 is pulled toward the fixing block 4 as a whole, but at the time of the pulling, the protrusion 54 formed on the back surface of the pressing plate 51 is inserted into the tendon insertion hole 21. Since the wedge members 31, 31 are pushed in, the FRP tendon 6 sandwiched between them is firmly fixed to the fixing block 4.
[0032]
If the FRP tendon 6 is fixed to the tendon insertion hole 21 of the fixing block 4 in this way, the tension rod 61 having a male screw formed at the tip is connected to the rod hole of the presser plate 51 as shown in FIG. After passing through 52, it is screwed onto the female screw 9 of the fixing block 4.
[0033]
Next, as shown in FIG. 9, the reaction force member 71 and the center hole jack 72 are installed on the bearing plate 3 so that the tension rod 61 is penetrated.
[0034]
When the tension is ready in this way, the center hole jack 72 is driven. Then, the tension rod 61 is pulled in the direction indicated by the arrow in the figure by applying a reaction force to the bearing plate 3 via the reaction force member 71.
[0035]
In this way, the tensile force acting on the tension rod 61 is transmitted to the FRP tension member 6 via the fixing block 4 and the wedge 7 and the tension force is introduced into the tension member.
[0036]
Next, the lock nut is turned so that the gap generated between the lock nut 5 and the bearing plate 3 is eliminated, and if there is a gap between the protrusion 54 of the pressing plate 51 and the wedge member 31. Then, the bolt passed through the holding plate 51 is tightened, and the wedge member 31 is further pushed into the tension material insertion hole 21.
[0037]
Next, the center hole jack 72 is loosened to release the tension force of the tension rod 61.
[0038]
Then, the tension force of the FRP tension material 6 is transmitted to the bearing plate 3 via the wedge 7 and the fixing block 4, and prestress is introduced into the concrete frame 2.
[0039]
If prestress is introduced into the concrete housing 2, the center hole jack 72, the reaction force member 71, and the tension rod 61 are removed, and the state shown in FIG. After the end of the tension work, the grout is injected into the sheath 8 and a cover is attached to the bearing plate 3 as in the conventional PC construction. When the grout is injected, the female screw 9 of the fixing block 4 is inserted into the grout inlet. And it is sufficient.
[0040]
As described above, according to the PC fixing tool and the PC fixing method according to the present embodiment, the tension rod 61 is screwed onto the female screw 9 formed at the center of the fixing block 4 so as to give a tensile force thereto. Therefore, the plurality of FRP tension members 6 fixed by the tension material insertion holes 21 arranged so as to surround the female screw are collectively tensioned via the tension rod 61 and the fixing block 4.
[0041]
For this reason, when it is necessary to introduce a large prestress in response to an increase in the size or length of the structure, the time required for such work is higher than in the conventional case where the tension fixing work is performed on individual tension members. Can be greatly shortened, and variations in tension can be reduced.
[0042]
Further, according to the present embodiment, the pressing plate is drawn toward the fixing block 4 in a state where the projection 54 provided on the back surface of the pressing plate 51 is in contact with the end portion of the wedge member 31. 31 will be pushed into the tendon insertion hole 21 simultaneously and with equal force.
[0043]
Therefore, it is not necessary to individually drive the wedge members individually with a woodcutter or the like as in the prior art, and the wedge driving operation can be shortened and the wedge pressing operation can be performed uniformly.
[0044]
Moreover, according to this embodiment, since the tendon insertion hole 21 has a square hole-like cross section, the structure is optimal for fixing the FRP tendon 6 having a belt-like cross section, and the tension material is reliably tensioned and fixed. It becomes possible.
[0045]
In the present embodiment, the number of tendon insertion holes 21 is six, but it goes without saying that the number of fixing devices of the present invention is not limited to this number. FIG. 10 shows a fixing block 82 provided with twelve tension material insertion holes 81 through which the tension material is inserted on the assumption that twelve FRP tension materials are used.
[0046]
Further, in this embodiment, the wedge members 31 and 31 inserted into the tension material insertion hole 21 are fixed using the presser plate 51. You may make it come in.
[0047]
Even in such a configuration, the effect of collectively tensioning the tendon can be enjoyed similarly to the above-described embodiment.
[0048]
Further, in the present embodiment, it is assumed that the FRP tendon is used, but the fixing device of the present invention is not limited to the FRP tendon, and a conventionally used PC steel may be used. .
[0049]
FIG. 11 shows a fixing block 91 suitable when a PC steel material having a circular cross section is used as a tension material. As shown in the figure, the fixing block 91 is formed with a tension material insertion hole 92 having a conical inner surface 93. When the fixing block 91 is used, the wedge members 94a, 94b, 94c having a conical outer surface as shown in FIG. 12 are divided into the PC steel members 95 as shown in FIG. What is necessary is just to make it insert in the tension material insertion hole 92 in the state pinched | interposed.
[0050]
Even in such a configuration, as described above, since the collective tension can be performed, it is possible to greatly reduce the time required for the tension work, and by using a pressing plate similar to the pressing plate 51, It becomes possible to push the wedge members 94a, 94b, 94c having an outer surface into the tendon insertion hole 92 simultaneously and with equal force.
[0051]
【The invention's effect】
As described above, according to the PC fixing device of the present invention according to claim 1, it is possible to collectively tension a plurality of tension members, and the time required for the tension work can be greatly shortened.
[0052]
In addition, according to the PC fixing device of the present invention according to claim 1, the structure is optimal for fixing the FRP tendon having a strip-shaped cross section, and the tension and fixing of the tendon can be reliably performed. Play.
[0053]
Further, according to the PC fixing device of the present invention according to claim 2, in addition to the effect of claim 1, it is possible to push the wedge members into the tendon insertion holes simultaneously and with equal force. There is also an effect.
[0054]
Further, according to the PC fixing method of the present invention according to claim 3, it is possible to collectively tension a plurality of tension members, and the time required for the tension work can be greatly shortened.
[0055]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a PC fixing device according to an embodiment.
2A and 2B are diagrams of a fixing block constituting the PC fixing device according to the present embodiment, in which FIG. 2A is a front view, and FIG. 2B is a detailed cross-sectional view taken along line AA in FIG.
FIG. 3 is a view of a wedge constituting the PC fixing device according to the present embodiment, where (a) is a front view seen from the front side of the tendon insertion hole, and (b) is along the line BB. Sectional view, (c) is a plan view seen from the direction of line CC.
4A and 4B are diagrams of a lock nut constituting the PC fixing device according to the present embodiment, in which FIG. 4A is a front view, and FIG. 4B is a cross-sectional view taken along line DD in FIG.
FIG. 5 is a diagram showing a procedure of a PC fixing method according to the present embodiment.
FIG. 6 is a view showing a state in which a pressing plate is attached in the PC fixing method according to the present embodiment.
FIG. 7 is a rear view showing a pressing plate used in the PC fixing method of the embodiment.
FIG. 8 is a diagram showing a state in which a tension rod is screwed onto a female screw of a fixing block in the PC fixing method according to the present embodiment.
FIG. 9 is a diagram showing a state in which a tensile force is applied to the tension rod in the PC fixing method according to the present embodiment.
FIG. 10 is a front view showing a fixing block according to a modification.
FIGS. 11A and 11B are diagrams illustrating a fixing block according to another modification, in which FIG. 11A is a front view, and FIG. 11B is a detailed cross-sectional view along the line EE.
12A and 12B are diagrams showing a wedge used in the fixing block of FIG. 11, wherein FIG. 12A is a front view, FIG. 12B is a perspective view of a wedge member constituting the wedge, and FIG. The whole perspective view of a state.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixing tool 2 Concrete frame 3 Supporting pressure plate 4, 82, 91 Fixing block 5 Lock nut 6 FRP tension material (tensile material)
7 Wedge 9 Female thread 21, 81, 92 Tension material insertion hole 22 Tapered inner surface 31, 94a, 94b, 94c
Wedge material (wedge)
51 Holding plate 54 Protrusion 61 Tension rod 95 PC steel (tensile material)

Claims (3)

  A bearing plate attached in the vicinity of the surface of the concrete frame, a cylindrical fixing block that is configured to be freely fitted into the bearing plate and has a plurality of radial insertion holes, and screwed into the outer peripheral surface of the fixing block An annular lock nut for locking the fixing block to the bearing plate, and a plurality of wedges inserted so as to sandwich the tension material in each of the tension material insertion holes, A PC fixing device in which a female screw to which a predetermined tension rod is detachably screwed is formed in a region surrounded by a tension material insertion hole, and the cross section of the tension material insertion hole is formed in a square hole shape. A pair of opposed inner surfaces is formed in a tapered shape, and the wedge is formed in a tapered shape so that one surface is in contact with the tapered inner surface of the insertion hole for the tension material, and the other surface is formed in a band shape. PC fixing device, characterized in that is composed of a pair of wedge members has a contact surface with the stretched member, and configured so as to sandwich the strip tension member at the pair of wedge members.   2. A pressing plate comprising a protrusion abutting against an end of the wedge inserted into the tendon insertion hole and a bolt hole for attachment to the fixing block. The PC fixing device as described.   A tension material is inserted into a plurality of tension material insertion holes formed radially in a cylindrical fixing block, and the fixing block is fitted into a bearing plate attached in the vicinity of the surface of the concrete frame, and on the outer peripheral surface of the fixing block. The fixing is surrounded by the tensioning material insertion hole while being engaged with the tensioning material insertion hole by engaging with the pressure-bearing plate with a threaded annular lock nut and sandwiching the tensioning material in each of the tensioning material insertion holes. A predetermined tension rod is screwed onto a female screw formed in a block region, and a tension force is introduced into the tension material by applying a tensile force to the tension rod while taking a reaction force from the bearing plate, and the lock nut To remove the gap formed between the pressure plate and release the tension force of the tension rod to transmit the tension force of the tension material to the pressure plate. A PC fixing method for removing the tension rod, wherein a cross-section of the insertion hole for the tension material is a square hole, and a pair of opposed inner surfaces is formed in a taper shape, and the wedge is used for the tension material on one surface A pair of wedge members formed in a taper shape so as to be in contact with the taper inner surface of the insertion hole and having the other surface as a contact surface with the belt-like tension member, and the pair of wedge members constitute the belt-like shape. A PC fixing method characterized by comprising a tension material.

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