JP6896444B2 - Fixing tool replacement method for PC structures - Google Patents

Description

The present invention relates to a method for refilling a fixing tool for a PC structure, in which a defective portion of the PC steel rod that applies prestress to the PC structure is removed, and then the PC steel rod is hooked and refilled with a newly set fitting. is there.

In recent years, PC steel rods of prestressed PC structures such as bridges have been corroded, and it has become necessary to remove or replace them. In particular, when a fixing tool is provided at or near the top of the bridge girder of the bridge (see Fig. 1), there is a cavity around the PC steel rod near the fixing part due to poor filling or breathing of the grout filled in the sheath. Or grout may be poorly cured. If there is a cavity or a poorly cured part, deterioration factors such as water and chloride ions may invade from there, and the PC steel rod may corrode and break. In addition, since strong prestress is applied to the PC steel rod, if it breaks, it will break through the concrete or asphalt pavement on the upper edge of the PC structure, and the PC steel rod will protrude from the surface of the PC structure, leading to a serious accident. There is a risk.

In addition, if the fixing tool is provided at the top of the girder, not only the grout may be poorly filled, but also the fixing portion may be damaged when the pavement is replaced. Therefore, if the PC steel rod itself is corroded or damaged, it is necessary to remove the corroded or damaged part of the PC steel rod and replace the set attachment part in order to maintain prestress. is there.

In Patent Document 1, in the intermediate fixing tool 1 of the PC steel material 7 for fixing the PC steel material 7 that remains exposed in a tense state in the dismantling / removing section in the intermediate portion of the existing continuous concrete structure, the PC steel material 7 is described. A steel pipe sleeve 2a formed by combining half-split sleeves 2a sandwiching the periphery while maintaining a predetermined annular gap 9, and a plurality of plates having an opening 4a and sequentially fitted to the outer periphery of the steel pipe sleeve 2 to reinforce the steel pipe sleeve 2. An intermediate fixing tool for a PC tensioning material having a C-shaped member 4 and an intermediate fixing method using the same are disclosed (claim 1, claim 1, paragraph [0017] of the specification. ] To [0021], see FIGS. 1, 3 and the like in the drawings).

The intermediate fixing method described in Patent Document 1 is a method of securing a frictional force with a PC steel material by a restraining pressure due to expansion of an expansion material, and is effective when a part of a PC structure is disassembled and removed by intermediate fixing. Is. However, the intermediate fixing method described in Patent Document 1 has not been proved in a long-term experiment that the restraining pressure due to the expansion of the expanding material is maintained, and the possibility that the PC steel material slips can be completely eliminated. There was a problem that there was no.

Further, in Patent Document 2, when a part of the PC structure is disassembled and removed, the tension material is exposed by scraping the periphery of the cutting position of the PC structure, and the intermediate fixing tool is fixed to the tension material. A cutting method for existing PC structures in which the part is backfilled, the exposed tension material is cut in that state, the end of the tension material is fixed with this setting tool, and then a part of the PC structure is disassembled and cut. (Refer to claim 1, claims of patent document 2, paragraphs [0010] to [0015] of the specification, FIG. 1 of the drawing, etc.).

However, in the cutting method of the existing PC structure described in Patent Document 2, the end portion of the tension material is fixed by the conventional setting tool, and the conventional setting tool is installed only on the surface of the structure. There is a problem that it can be applied only to the cutting method of the PC structure, which is reduced by dismantling and removing a part of the PC structure because it cannot be done. In addition, the conventional setting tool has a problem that the chipping range is increased by that amount because the setting tool is set at a place slightly away from the intermediate fixing tool.

Further, in the cutting method of the existing PC structure described in Patent Document 2, since the setting fitting is set at a place slightly away from the intermediate fixing tool, when the PC steel material stopped by the intermediate fixing tool slips, You will be prestressed with this set of clothing. Therefore, there is a risk that the prestress of the design cross section will be insufficient. Further, when the set fitting is a general rust type fixing tool, a set amount is required, which may reduce prestress. In addition, when the PC steel material is installed at an angle with respect to the surface of the structure, there is a problem that the prestress may decrease due to friction depending on the angle and distance.

Further, in Patent Document 3 proposed by the applicant of the present application, concrete is shaved to expose the tension material 61, and the exposed tension material 61 is provided with an upper frame 71, a lower frame 72, a fixing bolt 73, a ring 74, and the like. A method of repairing a PC structure in which an intermediate fixing tool 7 is attached, new concrete is cast by scraping existing concrete along the tension material 3 to which the intermediate fixing tool 7 is attached, and prestress is introduced after hardening. (Refer to claim 1, claims of patent document 3, paragraphs [0060] to [0071] of the specification, FIG. 1 of the drawing, etc.).

However, the method of repairing the PC structure described in Patent Document 3 is also configured to maintain prestress by the expanding force of the expanding material, similarly to the intermediate fixing method described in Patent Document 1. For this reason, it has not been proved whether the restraining pressure due to the expansion of the expanding material for a long period of time is maintained, and when it is simply applied to the refilling of the fixing tool of the PC structure, the PC steel rod slips and prestress occurs. There was a problem that the possibility of reduction could not be completely eliminated.

Japanese Unexamined Patent Publication No. 2007-277826 Japanese Unexamined Patent Publication No. 9-158126 Japanese Unexamined Patent Publication No. 2015-86534

Therefore, the present invention has been devised in view of the above-mentioned problems, and an object of the present invention is that a corroded portion or a damaged portion of a PC steel rod on which prestress acts in a PC structure can be safely removed. In both cases, it is an object of the present invention to provide a fixing tool refilling method for a PC structure in which there is no possibility that the PC steel rod will slip and the prestress will be reduced for a long period of time by mechanically hooking the PC steel rod.

The fixing tool replacement method for a PC structure according to the first invention is a fixing tool replacement method for a PC structure in which a defective portion of the PC steel rod is removed and the PC steel rod is hooked and replaced with a newly set fitting. In addition, a new part is added to the removal part specifying step of confirming the defective part and the sound part of the PC steel rod and specifying the removed part of the PC steel rod, and the remaining part of the removed part specified in the removing part specifying step. After the intermediate fixing tool mounting step of securing a predetermined range for mounting the setting fitting and mounting the intermediate fixing tool and the intermediate fixing tool mounting process, the predetermined range of the PC steel rod is processed to obtain a new setting fitting. The newly set fitting has a bearing plate and a plurality of nuts sandwiching the bearing plate, and the fixture mounting step includes cutting a predetermined range. Then, the thread groove is cut, and the nut is screwed into the thread groove to attach the pressure bearing plate .

The fixing tool replacement method for a PC structure according to the second invention is a fixing tool replacement method for a PC structure in which a defective portion of the PC steel rod is removed and the PC steel rod is hooked and replaced with a newly set fitting. The new parts are added to the removal part specifying step of confirming the defective part and the sound part of the PC steel rod and specifying the removed part of the PC steel rod, and the remaining part of the removed part specified in the removing part specifying step. After the intermediate fixing tool mounting step of securing a predetermined range for mounting the setting fitting and mounting the intermediate fixing tool and the intermediate fixing tool mounting step, the predetermined range of the PC steel rod is processed to obtain a new setting fitting. The newly set fitting includes a fixing tool mounting process for mechanically mounting, and the newly set fitting includes a half-split cylindrical body having ribs on the inner peripheral surface, a half-split disk integrated with the half-split cylindrical body, and It is composed of a pair of members, and in the fixing tool mounting step, a recess is formed in the predetermined range, the rib is fitted into the recess, and the newly set tool is fitted to the PC steel rod. It is characterized by that.

According to the first invention and the second invention, after the intermediate fixing tool attaching step, a predetermined range of the PC steel rod is processed and the newly set attachment is attached, so that the PC steel rod on which prestress acts in the PC structure Corroded and damaged parts can be safely removed. Further, according to the first invention and the second invention, since the PC steel rod is processed and the newly set fitting is mechanically attached, there is no possibility that the PC steel rod slips and the prestress is reduced for a long period of time. Moreover, according to the first invention and the second invention, since the newly set fitting is set adjacent to the intermediate fixing tool and mechanically fixed by the nut, the set amount is not generated. Therefore, even if the PC steel rod slips in the intermediate fixing portion, the prestress is easily transmitted to the design cross section.
In addition, according to the first invention, the outer peripheral surface of the PC steel rod is cut to cut a thread groove, and a nut is screwed into the thread groove to attach a bearing plate, so that the PC steel rod slips and prestresses. There is no risk of a decrease in stress for a long period of time, and there is no risk of loosening the tension when installing the newly set clothing.

In particular, according to the second invention, the fixing tool mounting process is completed only by forming a recess in the PC steel rod, fitting the rib into the recess, and fitting the newly set fitting to the PC steel rod. The time required to cut the thread groove is not required, the work time can be shortened, and the work cost of the fixing tool replacement work can be reduced.

It is a perspective view which represented the state of the box girder bridge to which this invention is applied schematically. It is a process explanatory drawing which shows the PC steel rod scraping process of the fixing tool refilling method of the PC structure which concerns on 1st Embodiment of this invention. It is a process explanatory drawing which shows the intermediate fixing tool mounting process of the same fixing tool replacement method. It is a perspective view which shows the intermediate fixing tool used in the fixing tool replacement method of the same above. It is a process explanatory drawing which shows the process of removing the corroded part of the same fixing tool refilling method. It is a process explanatory drawing which shows the main setting fitting attachment process of the same fixing tool replacement method. It is a partially enlarged view which shows the circumference of the fixing tool enlarged in FIG. 6, (a) is a figure which shows the screwed state before mounting of a fixing tool, (b) is a figure which shows after mounting of a fixing tool. It is a figure. It is a process explanatory drawing which shows the filling material placing process of the same fixing tool refilling method. It is a process explanatory drawing which shows the present setting fitting attachment process of the fixing tool replacement method of the PC structure which concerns on 2nd Embodiment of this invention. 9 is a partially enlarged view showing the circumference of the set fitting of FIG. 9, in which FIG. 9A is a view showing a state in which a recess is formed before mounting the fixing tool, and FIG. 9B is a view showing a state in which a recess is formed before mounting the fixing tool. It is a figure which shows. 9 is a perspective view showing a state in which the setting fitting of FIG. 9 is attached to a PC steel rod.

Hereinafter, an embodiment for carrying out the fixing tool replacement method for the PC structure according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, with reference to FIGS. 1 to 8, the box girder bridge will be described as an example of the PC structure by exemplifying the fixing tool replacement method for the PC structure according to the first embodiment of the present invention. First, the box girder bridge 1 to which the fixing tool replacement method for the PC structure according to the present embodiment is applied will be briefly described. FIG. 1 is a perspective view schematically showing a state of a box girder bridge to which the present invention is applied.

In a bridge, a PC steel rod is inserted into a sheath pipe to apply prestress to a PC structure at a place where a tensile force acts, such as near the end of the bridge girder or near the center bottom, to form a PC structure, and the tension of the PC steel rod is applied. The tensile force acting on the reinforced concrete by the force is offset and reduced. In the box girder 2 of the box girder bridge 1, as shown in FIG. 1, the PC steel rod 3 is generally arranged diagonally, and one end thereof is fixed by the preset fitting 4 near the top end of the box girder 2. Has been done.

However, as described in the background technology, when the fixing tool is provided at or near the top of the bridge girder, the PC steel rod 3 near the already set fitting 4 is corroded and broken due to poor filling of grout or the like. There is a risk. FIG. 1 shows a case where the PC steel rod 3 in the vicinity of the set fitting 4 in the broken line ellipse is corroded to become the corroded portion 30, and the rest is the sound portion 31 indicated by the alternate long and short dash line. Therefore, if left as it is, the PC steel rod 3 may break due to prestress, break through the concrete or asphalt pavement on the upper edge of the box girder 2, and the PC steel rod 3 may protrude and lead to a serious accident.

In the fixing tool replacement method for the PC structure according to the embodiment of the present invention, the corroded portion 30 of the PC steel rod 3 of the box girder bridge 1 and the pre-set fitting 4 are removed, and the box girder 2 of the PC steel rod 3 is used. The case where the fixing position is moved to the end of the sound portion 31 and the already set clothing 4 is replaced with the newly set clothing 5 will be described.

(1) Removal part identification step In the fixing tool replacement method of the PC structure according to the present embodiment, first, in the box girder bridge 1, the corroded part 30 and the sound part 31 which are defective parts of the PC steel rod 3 are confirmed. , Perform a removal part specifying step to specify the removing part of the PC steel rod 3.

In this process, a small-diameter hole is drilled from the side surface of the box girder 2 toward the sheath tube by roughly hitting the corroded portion 30 of the PC steel rod 3 due to cracks and rusting conditions, and a camera such as an endoscope is drilled. Observe the inside of the sheath tube with. As a result, the unfilled grout portion and the poorly cured grout portion in the sheath pipe are confirmed, the corroded portion 30 and the sound portion 31 of the PC steel rod 3 in the sheath pipe are confirmed, and the removed portion to be removed is specified. In the present embodiment, the upper end portion of the PC steel rod 3 is corroded to form a corroded portion 30, and the other portion is a healthy portion 31, so that the corroded portion 30 and the already set fitting 4 are left with the healthy portion 31 left. Is specified as the removed part.

The method of specifying the removed portion is not limited to the case where the hole is drilled and visually recognized with an endoscope or the like, and the corroded portion 30 of the PC steel rod 3 may be confirmed by X-rays or other methods. Needless to say. However, when the holes are drilled and visually recognized with an endoscope or the like, the unfilled grout portion and the like can also be confirmed and can be reliably identified.

(2) Grout reinjection step Next, in the fixing tool replacement method for the PC structure according to the present embodiment, a grout reinjection step of reinjecting the grout into the unfilled portion of the sheath tube confirmed in the previous step is performed. ..

In this process, a hole drilled for confirmation in the previous process is used, or a new hole is drilled from the side surface of the box girder 2 toward the sheath pipe at a necessary location, and the hole and the pump, chamber, etc. are drilled. The grout is press-fitted or re-injected under natural flow in connection with.

However, the grout is not re-injected into the upper edge portion above the removed portion specified in the previous step regardless of the presence or absence of the unfilled grout portion. This is because the corroded portion 30 of the PC steel rod 3 is later pulled out from the sheath pipe and removed.

Therefore, in the present embodiment, this step is executed only when the unfilled grout portion is present in the sound portion 31 of the PC steel rod 3.

(3) PC Steel Material Scraping Step Next, as shown in FIG. 2, in the fixing tool replacement method of the PC structure according to the present embodiment, the boundary between the corroded portion 30 and the sound portion 31 of the PC steel rod 3 is defined. A PC steel material scraping process is performed to scrape and expose. FIG. 2 is a process explanatory view showing a PC steel material scraping process of the fixing tool refilling method of the PC structure according to the present embodiment.

In this step, based on the range of the corroded part 30 and the sound part 31 confirmed in the removal part identification step, the rectangle of the side surface of the box girder 2 which is the boundary between the corroded part 30 and the sound part 31 of the PC steel rod 3 is shown in FIG. The broken line portion of the above is scraped to expose a certain range of the sound portion 31. Here, the fixed range is the length obtained by adding the length α of the intermediate fixing tool 6 to 100 mm, which is the mounting allowance of the newly set fitting 5, that is, 100 mm + α from the end of the sound portion 31. Of course, this range may be appropriately determined according to the length of the newly set fitting 5 and the intermediate fixing tool 6.

The direction of the chipping work may be from the outside as shown in the figure, or from the inside as long as it is put in the box girder 2. It is easy to install the scaffolding from the inside.

(4) Intermediate Fixing Tool Mounting Step Next, as shown in FIG. 3, in the fixing tool replacement method of the PC structure according to the present embodiment, the sound portion 31 of the PC steel rod 3 scraped out in the previous step is covered. The intermediate fixing tool attaching step for attaching the intermediate fixing tool 6 is performed. FIG. 3 is a process explanatory view showing an intermediate fixing tool attaching process of the fixing tool replacement method of the PC structure according to the present embodiment.

FIG. 4 is a perspective view showing an intermediate fixing tool used in the fixing tool replacement method of the PC structure according to the present embodiment. As shown in FIG. 4, the intermediate fixing tool 6 is the same as the intermediate fixing tool described in Patent Document 1, and is fitted into a pair of half-split tubular sleeves 60 and 61 and the sleeves 60 and 61. It is composed of a plurality of C-shaped steel plates 62 that prevent the sleeves 60 and 61 from coming off. The sleeves 60 and 61 are provided with an injection port 63 for injecting an expansion material provided near the seam and an exhaust port 64 for exhausting air corresponding to the volume of the expansion material injected from the injection port 63. There is.

The sleeves 60 and 61 are water-stopped with a water-stopping tape whose seams are not shown, and water-stopping rubber is installed at the end of the inner peripheral surface to form a gap with the PC steel rod 3 at regular intervals. The mechanism is such that the material does not leak.

Further, in the C-shaped steel plate 62, as shown in FIG. 4, a plurality of C-shaped steel plates 62 are arranged side by side while rotating little by little to cover the sleeves 60 and 61 so that the openings are not aligned and become a weak point in strength. It is provided as follows. The C-shaped steel plate shown in the figure shows only a part, and is actually provided so as to cover all the outer peripheral surfaces of the sleeves 60 and 61.

Reference numeral 65 is a bearing plate for preventing the prestress acting on the existing PC steel rod 3 from being loosened by being brought into contact with the existing concrete left behind. In this step, the pressure plate 65, which is on the sound portion 31 side of the intermediate fixing tool 6, is attached in close contact with the existing concrete that has been left unscraped (see FIG. 3). This is to prevent the prestress acting on the existing PC steel rod 3 from loosening.

(5) Corroded Part Removal Step Next, as shown in FIG. 5, in the fixing tool replacement method of the PC structure according to the present embodiment, the exposed PC steel rod 3 is cut and the corroded part 30 which is the removed part is cut. In addition, the corroded portion removing step of removing the existing set fitting 4 is performed. FIG. 5 is a process explanatory view showing a step of removing the corroded portion of the fixing tool replacement method of the PC structure according to the present embodiment.

The position where the PC steel rod 3 is cut in this step is the boundary between the corroded portion 30 and the sound portion 31, and is the position when the removed portion is specified in the removed portion specifying step. This cutting position is about 100 mm in the present embodiment from the ends of the sleeves 60 and 61 of the intermediate fixing tool 6 in consideration of the length of the newly set fitting 5 described later.

As described above, in this step, the intermediate fixing tool 6 attached in the previous step receives the tension of the prestress applied to the PC steel rod 3 for cutting, so that the prestress acting on the corroded portion 30 which is a limited range is applied. It will only be released. Therefore, the displacement of the PC steel rod 3 due to the release of prestress is also limited, the impact at the time of cutting can be reduced, and the risk of the PC steel rod 3 protruding can be reduced.

(6) Setting Tool Installation Step Next, as shown in FIGS. 6 and 7, in the fixing tool replacement method for the PC structure according to the present embodiment, the new setting tool 5 which is the setting tool is used. This setting to be attached Performs the attachment attachment process. FIG. 6 is a process explanatory view showing the main setting fitting attachment step of the fixing tool replacement method of the PC structure according to the present embodiment. FIG. 7 is a partially enlarged view showing the circumference of the main setting clothing of FIG. 6 in an enlarged manner, and FIG. 7A is a view showing a threaded state before mounting the new setting clothing 5, FIG. 7B. Is a diagram showing after the new setting fitting 5 is attached.

In this step, first, as shown in FIG. 7A, a predetermined range in which the newly set fitting 5 is attached from the tip (edge on the cutting side) of the PC steel rod 3 which is the remaining portion cut and removed in the previous step. A thread groove 32 is formed by cutting a range (in this embodiment, about 100 mm as described above) with a thread cutting machine or the like. Then, as shown in FIG. 7B, the nut 51 is screwed into the thread groove 32, the bearing plate 50 is attached, and the bearing plate 50 is sandwiched and sandwiched between the two nuts 51. The setting fitting 5 is attached to the PC steel rod 3.

(7) Filler casting process Next, as shown in FIG. 8, in the fixing tool replacement method for the PC structure according to the present embodiment, the concrete indicated by the shaded portion scraped in the PC steel material scraping step. A filler placing process is performed in which new concrete is placed in the part and backfilled. FIG. 8 is a process explanatory view showing a filler placing process of the fixing tool refilling method of the PC structure according to the present embodiment.

Of course, the filler to be cast in this step is not limited to concrete, and non-shrink mortar may be cast, or early-strength cement may be used to promote the development of a predetermined strength. In short, it suffices if the shaded portion scraped off in the PC steel scraping step can be backfilled with a filler exhibiting a strength equal to or higher than that of the existing concrete.

As described above, the fixing tool replacement work by the fixing tool replacement method for the PC structure according to the first embodiment of the present invention is completed.

According to the fixing tool replacement method for the PC structure according to the present embodiment, after the intermediate fixing tool 6 is attached, the corroded portion 30 and the like of the PC steel rod 3 are cut and removed, so that the prestressed PC is applied. The corroded portion 30 of the steel rod 3 and the set fitting 4 can be safely removed.

Further, according to the fixing tool replacement method of the PC structure according to the present embodiment, after the intermediate fixing tool attaching step, the sound portion 31 of the PC steel rod 3 is cut to form the screw groove 32. After that, the nut 51 is screwed into the thread groove 32 to sandwich the bearing plate 50, and the newly set fitting 5 is mechanically attached to the PC steel rod 3. Therefore, the tension force of the PC steel rod 3 is maintained based on the highly reliable mechanical mechanism of the steel material, and there is no possibility that the prestress applied to the PC steel rod 3 will be reduced for a long period of time. There is no risk that the tension will loosen when the newly set clothing 5 is attached.

[Second Embodiment]
Next, with reference to FIGS. 9 to 11, the fixing tool replacement method for the PC structure according to the second embodiment of the present invention will be described. A case where the fixing tool replacement method for the PC structure according to the second embodiment is applied to the box girder bridge 1 shown in FIG. 1 will be described.

The difference between the fixing tool replacement method for the PC structure according to the second embodiment and the fixing tool replacement method for the PC structure according to the first embodiment is the form of the newly set fitting and the mounting method thereof. .. Therefore, this point will be mainly described, and the description of the same step will be omitted.

In the fixing tool replacement method for the PC structure according to the second embodiment, as in the fixing tool replacement method for the PC structure according to the first embodiment, (1) removal part identification step to (5) corroded part removal. Perform the process. Since the same procedure is used, the description thereof will be omitted.

(6) Setting Tool Mounting Step Next, as shown in FIG. 9, in the fixing tool replacement method of the PC structure according to the present embodiment, a book for mounting the new setting tool 5'which is the setting tool. Perform the setting tool mounting process. FIG. 9 is a process explanatory view showing the main setting fitting attachment step of the fixing tool replacement method of the PC structure according to the present embodiment.

The new setting fitting 5'attached in this step is the main setting fitting made of steel material, and as shown in FIGS. 10 and 11, the half-split cylinder and the half-split disk are integrated (shown). It is mainly composed of a pair of fixing members 50'and 51'. Further, a ring-shaped rib 52'is formed on the inner peripheral surface of the half-split cylinder of the fixing members 50'and 51' (see FIG. 10B). 10 is a partially enlarged view showing the circumference of the main setting clothing of FIG. 9 in an enlarged manner, and FIG. 10A is a view showing a state in which a recess is formed before mounting the new setting clothing 5', (b). ) Is a diagram showing after the new setting fitting 5'is attached. Further, FIG. 11 is a perspective view showing a state in which the setting fitting of FIG. 9 is attached to the PC steel rod 3.

In this step, first, as shown in FIG. 10A, the tip (edge on the cutting side) of the PC steel rod 3 which is the remaining portion cut and removed in the previous step corresponds to the rib 52'of the newly set fitting 5'. A ring-shaped recess 32'is formed at the position where the ring is formed. The method for forming the ring-shaped recess 32'may be any processing method such as cutting or pressing.

After that, as shown in FIG. 10B, the position of the rib 52'of the newly set fitting 5'and the position of the recess 32'are aligned, and as shown in FIG. 11, C made of a steel material. The shape ring 53'is fitted on the outer peripheral surfaces of the fixing members 50' and 51', and the newly set fitting 5'is fitted on the PC steel rod 3. Of course, the fitting method between the fixing members 50'and 51'is not limited to the C-shaped ring 53', and other fitting methods such as providing a flange and screwing may be used.

Next, in the fixing tool replacement method for the PC structure according to the second embodiment, (7) the filler placing step is performed in the same manner as the fixing tool replacement method for the PC structure according to the first embodiment. As a result, the fixing tool replacement work by the fixing tool replacement method for the PC structure according to the present embodiment is completed.

According to the fixing tool replacement method according to the present embodiment, after the intermediate fixing tool 6 is attached, the corroded portion 30 and the like of the PC steel rod 3 are cut and removed, so that the corroded portion of the PC steel rod 3 on which prestress acts is applied. 30 and the pre-set clothing 4 can be safely removed.

Further, according to the fixing tool replacement method according to the present embodiment, after the intermediate fixing tool mounting step, a ring-shaped recess 32'is formed in the sound portion 31 of the PC steel rod 3, and the rib 52'is formed in the recess 32'. Is fitted, and the newly set fitting 5'is mechanically attached to the PC steel rod 3. Therefore, the tension force of the PC steel rod 3 is maintained based on the highly reliable mechanical mechanism of the steel material, and there is no possibility that the prestress applied to the PC steel rod 3 will be reduced for a long period of time. , There is no risk of loosening the tension when attaching the newly set clothing 5'.

In addition, according to the fixing tool replacement method according to the present embodiment, the recess 32'is formed in the PC steel rod 3, and the rib 52'of the newly set fitting 5'is fitted into the recess 32'. The fixing tool mounting process is completed simply by fitting the setting tool 5'on the PC steel rod 3. Therefore, as compared with the fixing tool replacement method for the PC structure according to the first embodiment, the time for cutting the screw groove is not required, the working time is shortened, and the work cost of the fixing tool replacement work is reduced. can do.

The fixing tool replacement method for the PC structure according to the first embodiment and the second embodiment of the present invention has been described in detail above, but any of the above-mentioned or illustrated embodiments are specific in carrying out the present invention. It merely shows one embodiment, and the technical scope of the present invention should not be construed in a limited manner by these.

In particular, as the intermediate fixing method, the method of maintaining the prestress of the PC steel material by the expansion pressure of the expanding material has been described as an example in the same manner as the intermediate fixing method described in Patent Document 1, but the intermediate fixing method described in Patent Document 3 has been described. It may be the same as the method, or other intermediate fixing method may be used. In short, any method can be used as long as the prestress of the PC steel material can be temporarily maintained.

1: Box girder bridge 2: Box girder 20, 20': Anchor hole 3: PC steel rod 30: Corroded part (defective part)
31: Sound part 32: Thread groove 32': Recessed portion 4: Already set fittings 5, 5': Newly set fittings 50: Support plate 51: Nuts 50', 51': Fixing member 52': Ribs 53': C type Ring 6: Intermediate fixing tool 60, 61: Sleeve 62: C-shaped steel plate 63: Injection port 64: Exhaust port 65: Support plate

Claims (2)

It is a fixing tool replacement method for PC structures, in which the defective part of the PC steel rod is removed, and then the PC steel rod is hooked and replaced with the newly set fitting.
A removal part identification step of confirming a defective part and a sound part of the PC steel rod and specifying the removed part of the PC steel rod,
An intermediate fixing tool mounting step of securing a predetermined range for mounting a new setting fitting and attaching an intermediate fixing tool to the remaining portion of the removed portion specified in the removing portion specifying step.
After the intermediate fixing tool mounting step, the fixing tool mounting step of processing the predetermined range of the PC steel rod and mechanically mounting the newly set fitting is provided .
The newly set fitting has a bearing plate and a plurality of nuts that sandwich the bearing plate.
In the fixing tool attaching step, the fixing tool replacement of the PC structure is characterized in that the predetermined range is cut to cut a thread groove, and the nut is screwed into the thread groove to attach the pressure bearing plate. Construction method. It is a fixing tool replacement method for PC structures, in which the defective part of the PC steel rod is removed, and then the PC steel rod is hooked and replaced with the newly set fitting.
A removal part identification step of confirming a defective part and a sound part of the PC steel rod and specifying the removed part of the PC steel rod,
An intermediate fixing tool mounting step of securing a predetermined range for mounting a new setting fitting and attaching an intermediate fixing tool to the remaining portion of the removed portion specified in the removing portion specifying step.
After the intermediate fixing tool mounting step, the fixing tool mounting step of processing the predetermined range of the PC steel rod and mechanically mounting the newly set fitting is provided .
The newly set clothing is composed of a pair of members consisting of a half-split cylinder having ribs on the inner peripheral surface and a half-split disk integrated with the half-split cylinder.
In the fixing tool attaching step, a PC structure is characterized in that a recess is formed in the predetermined range, the rib is fitted into the recess, and the newly set fitting is fitted to the PC steel rod. Fixing tool replacement method.

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