JP2017193899A - Widening structure of existing PC floor slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen a floor slab by introducing prestress to a widened portion with additional concrete, such that to ensure continuation with an existing floor slab, and without hindering a service by an existing bridge.SOLUTION: Concrete of a floor slab 2a is chipped to expose a tensile material 3, at a location away from an anchored end of the tensile material 3 anchored near a widening side end, in an axial direction of the tensile material, but coming close within a range that enables introduced tensile force in the tensile material to be maintained. An intermediate anchorage device 10 is fitted on the tensile material, and re-filling concrete is cast for embedding the intermediate anchorage device and fixing integrally with the concrete floor slab. Then, concrete on the tensile material on the anchoring end on the widened side is chipped, and the existing anchorage device 5 is removed and a connecting tool 20 is fitted, for connecting an extension tensile material 4. Concrete is cast in the widened portion, and prestress is introduced by applying tension to the extension tensile material 4.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for widening a concrete floor slab of an existing bridge, and more particularly to a method for widening a floor slab in which a tension material in the width direction of the floor slab is arranged and prestress is introduced.

  For existing bridges, it may be necessary to increase the width of the roadway or the width of the shoulder in order to improve or improve its function. When the bridge has a concrete slab, the concrete slab is widened. In a concrete floor slab where tension material is arranged in the width direction of the bridge and prestress is introduced, the side edge of the widening side is hung, and reinforcing bars are connected to add new concrete continuously. In addition, it is desirable to introduce prestress into concrete that has been newly laid by placing tendons.

For example, Patent Document 1 or Patent Document 2 describes a method of placing a tension material on concrete that has been added to widen a floor slab and introducing prestress.
In the method described in Patent Document 1, a horizontal hole is formed in a horizontal direction from a side end surface of an existing concrete floor slab, a PC steel rod is inserted into the horizontal hole, and a grout is injected and cured. This PC steel bar is connected with a tension material to be arranged at the portion to be widened, and after newly adding concrete, the tension material is tensioned to introduce prestress into the floor slab of the widened portion. Generally, the fixing end portion of the tension member arranged on the existing concrete floor slab is cut short after fixing, and it is difficult to introduce a pre-stress by connecting a new tension member to the existing tension member. In the technique described in the above-mentioned Patent Document 1, a PC steel rod is newly embedded in the existing concrete floor slab separately from the existing tension material to connect the tension material of the widened portion, so that the existing tension material is left as it is. It is possible to introduce prestress into concrete that has been added.

  In the method described in Patent Document 2, the concrete of the side edge portion to be widened of the existing concrete floor slab is suspended, the fixing device of the existing tension material is once removed, and a new tension material is connected. . After the concrete in the widened portion is cast and hardened, the connected tension material is tensioned and pre-stress is introduced into the widened portion. In this method, it is assumed that the tension material embedded in the existing floor slab is sufficiently adhered to the concrete of the existing floor slab by grout etc., and the loss of tension is small even if the fixing tool is removed. .

JP 2007-63796 A JP 2014-148870 A

However, the above prior art has the following problems that are desired to be solved.
In the method described in Patent Document 1, it is necessary to drill deep horizontal holes in an existing floor slab, which increases costs and may cause damage to the existing floor slab and existing tension members. In addition, since the tension force is transmitted from the tension material in the widened portion to the PC steel bar embedded separately from the existing tension material, it is considered that a complicated stress state occurs near the connection part of the old and new floor slabs. .
Further, in the method described in Patent Document 2, if a sufficient grout is not filled in the sheath in which the existing tension material is arranged, the tension force is loosened when the fixing device for the existing tension material is removed. The prestress of the existing floor slab will be insufficient.

  The present invention has been made in view of the circumstances as described above, and its purpose is to reduce existing obstruction of existing bridges while reducing the existing floor slab to a widened portion newly added with concrete. The present invention provides a method for widening a floor slab in which pre-stress is introduced so that the floor slab can be widened continuously.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a method of widening a concrete floor board in which a tension material is arranged in the width direction of a bridge and prestress is introduced, Close to the fixing end within the range where the tensioning force of the tensioning material can be maintained at a position away from the fixing end fixed in the vicinity of the side edge on the widening side in the axial direction of the tensioning material. A step of exposing the concrete of the floor slab at a position where the tension material is exposed; a step of attaching an intermediate fixing tool to the exposed tension material; and a portion of the floor slab where the concrete is sandwiched. Placing concrete, embedding the intermediate fixing tool and fixing it integrally with the concrete floor slab, holding the concrete covering the fixing end on the side where the tension material is widened, and removing the existing fixing tool A step of exposing a length at which an end of the tendon can be attached; a step of attaching a connecter to the tendon and connecting an extension tendon; and continuous with the floor slab Then, the concrete of the widened portion of the floor slab is placed, and after the concrete of the widened portion that has been placed is hardened, a prestress is introduced to the concrete of the widened portion by introducing tension to the tension material for extension. And a method for widening the floor slab including the step of:

In this slab widening method, the tensioning material is exposed at a position close to the anchoring end of the existing tensioning material, and the intermediate fixing tool is attached, so the existing fixing tool must be removed while maintaining the tension force in a wide range. Can do. In addition, since the intermediate fixing tool is integrated with the existing floor slab by attaching it to the tension material and then embedding with concrete, intermediate fixing is performed with a small number of steps, and pre-stress is maintained up to the backfilled part. It is possible to continue operation for a wide range of floor slabs.
On the other hand, the extension tendon arranged in the widened portion is connected to the existing tendon, so that prestress can be continuously introduced into the old and new concrete. And in connection, since the fixing tool of the existing tendon is removed and limited to the range necessary for the connection, it is exposed, and the range in which the existing concrete is hung is reduced. Therefore, it is possible to reduce the range in which the existing concrete is held for the intermediate fixing and the connection of the tendon, and to reduce the possibility that the existing floor slab is damaged.

  The invention according to claim 2 is the floor slab widening method according to claim 1, wherein the connector is a cylindrical female cone into which the tendon is inserted into a hollow hole, and a hollow hole in the female cone. A wedge-shaped male cone inserted between the inner peripheral surface of the tension member and the outer peripheral surface of the tendon, and a nut to be twisted onto a male screw formed on the outer peripheral surface of the female cone, A step of grasping a female cone to tension the tension material, introducing a tension force from the intermediate fixing tool to the connection tool, and a step of rotating the nut and fixing the tension material via the connection tool. And.

  This floor slab widening method uses a cylindrical female cone and a wedge-shaped male cone to connect a new tendon regardless of whether the existing tendon is a steel rod or a stranded steel wire. In addition, tension can be introduced and fixed at the connecting portion. Then, by introducing and fixing the tension force, the pre-stress is reintroduced from the attachment position of the intermediate fixing tool to the connection position of the tension material, and the male cone is properly pushed between the tension material and the female cone. Thus, it is possible to confirm the state in which the tendon is securely connected.

  The invention according to claim 3 is the floor slab widening method according to claim 1 or 2, wherein a plurality of the tension members are arranged at predetermined intervals in the axial direction of the bridge, The step of exposing the tension material by using the concrete of the floor slab is performed every other plurality of the tension materials, and the step of attaching the intermediate fixing tool and the step of placing the backfill concrete are performed. Then, after the concrete for backfill is hardened, a step of exposing the adjacent tendon is performed.

  In this floor slab widening method, when a plurality of existing tension members are arranged at a narrow interval, the concrete is suspended until the tension members are exposed while the tension force introduced to the tension members is reliably maintained. Work can be done. That is, when the concrete is hung until the tendon is exposed, it is possible to prevent the surroundings of the hung portion from being damaged and the tension of the tendon from being lost.

  As described above, in the method of widening a floor slab according to the present invention, the tension member is connected to the existing tension member while maintaining the tension force in a wide range by simply protruding the portion where the intermediate fixing tool is mounted and the fixing portion. In addition, prestress can be continuously introduced into the widened portion where the concrete is newly placed and the existing floor slab portion.

It is a schematic sectional drawing which shows the state by which the bridge which can apply the floor-widening method of the floor slab which concerns on this invention, and the general bridge were widened. It is the schematic sectional drawing and schematic plan view which show the process of widening the floor slab of the bridge shown in FIG. It is the schematic sectional drawing and schematic plan view which show the process of widening the floor slab of the bridge shown in FIG. It is the schematic sectional drawing and schematic plan view which show the process of widening the floor slab of the bridge shown in FIG. FIG. 5 is a side view, a front view, and a plan view showing an intermediate fixing tool that can be used in the floor slab widening method shown in FIGS. 2 to 4. FIG. 5 is a cross-sectional view showing a tension member connecting device that can be used in the floor slab widening method shown in FIGS. 2 to 4. FIG. 5 is a side view, a front view, and a plan view showing another example of an intermediate fixing tool that can be used in the floor slab widening method shown in FIGS. 2 to 4. It is sectional drawing which shows the other example of the connection tool which can be used with the method of widening the floor slab shown in FIGS. It is a schematic sectional drawing which shows the other aspect of the floor slab widened by applying the floor slab widening method of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a bridge to which the method for widening a slab of the present invention can be applied, and a state in which the bridge is widened.
This bridge has a plurality of main girders 1 made of concrete, and the upper part thereof is continuous with a concrete floor slab 2. The concrete floor slab 2 is formed so as to connect all the main girders 1, and tension members 3 are arranged in the width direction of the bridge in the floor slab. Prestress is introduced by introducing a tension force to the tension member 3 and fixing it at both side ends of the floor slab 2.

  The method of widening a floor slab according to the present invention can be applied to such a bridge widening. For example, as shown in FIG. 1B, the floor slab of the portion protruding to one side is extended to the floor. The plate 2 can be widened. In the widened portion 2b, new concrete is placed so as to be continuous with the existing floor slab 2a, and the new tension material 4 connected to the existing tension material 3 is tensioned to pre-load the widened portion 2b. Stress has been introduced.

Next, an embodiment of a method for widening the bridge slab will be described.
As shown in FIGS. 2 (a) and 2 (b), the floor slab is located near the side end on the side where the floor slab is to be widened, away from the fixing end of the tendon 3 in the axial direction of the tendon 3 as shown in FIGS. The tension material 3 is exposed through the concrete of the plate 2a. The position where the concrete of the floor slab 2a is held is as close as possible within a range in which the tensioning force of the tensioning material 3 can be maintained until the tensioning material 3 is exposed.
The range where the use of the bridge is restricted can be reduced by the position where the concrete on the floor slab is close to the anchoring end, but if the concrete is pulled too close to the anchoring end, the tension will be reduced. The force acting from the material 3 may cause the concrete near the fixing end to be damaged. When the concrete near the fixing end is damaged, the tension of the tension member 3 is loosened, and the prestress of the floor slab 2 may be insufficient. Therefore, until the tension material 3 is exposed, the concrete is suspended as close to the fixing end as possible within the range in which the tension force of the tension material 3 is maintained, and the tension material 3 is exposed.

When the tendon 3 is exposed, as shown in FIGS. 2 (c) and 2 (d), the intermediate fixing tool 10 is attached to this portion. The intermediate fixing tool 10 is fixed to the tension member 3, and the tension force of the tension member 3 can be transmitted to the concrete of the floor slab 2a via the intermediate fixing tool 10, and for example, the one shown in FIG. 5 is used. be able to.
An intermediate fixing tool 10 shown in FIG. 5 is attached to an intermediate portion of the tension member 3 into which tension is introduced, and includes a fixing block 13 including two halved blocks 11 and 12 and two halves. A plurality of bolts 14, which are coupling means for coupling the blocks 11 and 12 together, and a wedge 15 for fixing the fixing block 13 to the tension member 3 are provided. The two halved blocks 11 and 12 are both made of steel, and the outer shape is substantially a rectangular parallelepiped. When these are overlapped, a hollow hole 16 having a substantially circular cross-sectional shape is formed between the half blocks 11 and 12.

  The two half blocks 11 and 12 are provided with a plurality of bolt holes 17 and 18, respectively, which are arranged on both sides of the hollow hole 16 formed between the two half blocks 11 and 12. . Then, the bolt 14 inserted into the bolt hole 17 provided in the first half block 11 is screwed into the bolt hole 18 formed in the second half block 12 and having an internal thread on the inner peripheral surface, By tightening, the first half block 11 and the second half block 12 can be coupled together.

  The hollow hole 16 is formed by forming grooves each having a semicircular cross section on the opposing surfaces of the half blocks 11 and 12 coupled to each other, and tension is introduced into the two half blocks 11 and 12. The tension material 3 can be made to be inserted into the hollow hole 16 by being opposed from both sides of the tension material 3 in a state where the tension material 3 is located in the groove. The inner diameter of the hollow hole 16 is within a predetermined length from the upstream end in the direction in which the tendon 3 is pulled when the intermediate fixer 10 fixes the tendon 3 (direction indicated by arrow A in FIG. 5). The inner diameter is gradually reduced.

  The wedge 15 is divided into a plurality of parts, each of which has a shape in which the cross-section is reduced from one end to the other, and the inside of the hollow hole 16 is within a range in which the inner diameter of the hollow hole 16 of the fixing block 13 is reduced. It is inserted between the peripheral surface and the tension material 3. Thereby, the fixing block 13 can be firmly fixed to the tendon 3.

  When the intermediate fixing tool 10 is fixed to the tendon 3, as shown in FIGS. 3 (a) and 3 (b), uncured concrete is applied to the portion where the concrete is put to expose the tendon 3. The intermediate fixing tool 10 is embedded and integrated with the concrete of the existing floor slab 2a. At this time, the concrete to be newly placed is surely filled between the end face of the intermediate fixing tool 10 on the side where the tension member 3 is tensioned and the concrete of the existing floor slab 2a, and the intermediate fixing tool 10 acts. It is assumed that the supporting pressure is transmitted to the existing concrete. Further, mortar or the like may be separately filled between the end surface of the intermediate fixing tool 10 on the side where the tension member 3 is tensioned and the existing concrete.

  After the concrete placed so as to embed the intermediate fixing tool 10 is hardened, the concrete 2c of the fixing portion of the existing tension material 3 is suspended to expose the fixing tool 5. Then, as shown in FIGS. 3 (c) and 3 (d), it is assumed that the fixing device 5 is removed and the length of the tension member 3 to which the connecting device can be attached is exposed. Accordingly, the tension force introduced to the existing tension material 3 and fixed to the concrete of the floor slab 2a by the fixing tool 5 is released, and is fixed to the concrete of the floor slab 2a via the intermediate fixing tool 10. It becomes. That is, the tension force is released from the end of the tension member 3 from which the fixing tool 5 is removed to the intermediate fixing tool 10.

  As shown in FIGS. 4 (a) and 4 (b), a tendon connecting tool 20 is attached to the exposed end of the tendon 3. FIG. Before connecting the tension member 4 of the widened portion, the connection tool 20 can grip the connection tool 20 to tension the existing tension member 3 and fix it to the concrete of the existing floor slab 2a. ing. By tensioning and fixing the existing tension material 3 in this way, the tension force is again introduced from the end of the tension material 3 to the position where the intermediate fixing tool 10 is provided, and the existing floor slab 2a is widened. It is possible to return to the state where prestress is introduced to the vicinity of the edge.

For example, the connector 20 shown in FIG. 6 can be used.
As shown in FIG. 6A, the connecting tool 20 includes a female cone 21 having a male screw formed on a cylindrical outer peripheral surface, and an existing tension member inserted into a hollow hole of the female cone 21. 3 and a male cone 22 that functions as a wedge inserted between the inner peripheral surface of the hollow hole, a nut 23 that is twisted onto a male screw formed on the outer peripheral surface of the female cone 21, and an outer periphery of the female cone 21. A coupler 25 that is twisted together with a male screw formed on the surface and connected to an end of a new tension member 4 disposed in the widened portion is provided.

  The hollow hole provided in the female cone 21 has an inner diameter that decreases from the upstream side to the downstream side in the direction in which the tendon 3 is pulled. On the other hand, the male cone 22 is a wedge-shaped member divided into a plurality of parts, and unevenness is formed on the contact surface with the tension material 3 so that slippage between the tension material 3 is less likely to occur. The male cone 22 is pushed in between the tension material 3 and the inner peripheral surface of the female cone 22 from the upstream side in the direction A in which the tension material 3 is pulled, and is applied to the outer peripheral surface of the female cone 21 as shown in FIG. The tensioning rod 26 can be twisted and tensioned. Tensioning can be performed by bringing the center hole jack 27 into contact with the bearing plate 24 via the jack chair 28 and gripping the tensioning rod 26. As a result, the male cone 22 together with the tendon 3 is strongly drawn into the hollow hole of the female cone 21, and the tendon 3 and the female cone 21 are firmly fixed. Further, it is possible to fix the existing tension member 3 in a state where the tension force is again introduced by rotating the nut 23 in contact with the support plate 24 by further tension.

  The coupler 25 to be twisted onto the female cone 21 has a widening portion 4 as shown in FIG. 6A when the new tensioning material 4 arranged at the widening portion has a male screw at the end. It shall have the internal thread part twisted together. In addition, when a tendon fixed with a wedge such as a steel strand is used, the same female cone and male cone as those used to hold the existing tendon 3 are used, and a male formed similarly on the outer peripheral surface. It can be twisted to the threaded part. It is also possible to employ a coupler in which a coupler is locked to a female cone fixed to a new tendon.

  When the connecting tool 20 is attached to the existing tendon 3 and the tendon 4 arranged in the widened portion is connected, a formwork (not shown) of the widened portion is provided, a reinforcing bar (not shown) is assembled, and FIG. c) As shown in FIG. 4D, the concrete of the widened portion 2b is placed. Then, after the concrete is cured, the tension material 4 in the widened portion is tensioned and fixed by the fixing tool 6.

  By expanding the floor slab in this manner, a tension material continuous from the existing floor slab 2a to the floor slab 2b of the widened portion is arranged, and the pre-stressing is continued from the existing floor slab 2a to the floor slab 2b of the widened portion. Stress is introduced. Thereby, it can suppress that a damage arises in the side edge part of the existing floor slab 2a, or a complicated stress state generate | occur | produces. In addition, in the construction of the widening work, the bridge can be used while maintaining the prestress in a wide range of the existing floor slab 2a. And since concrete is hung near the side edge of the side to be widened and the existing tension material 3 is exposed and fixed by the intermediate fixing tool 10, the range of hung concrete can be suppressed to a small extent, and the service is limited. The range can be kept low.

The method for widening the floor slab according to the present invention is not limited to the above-described embodiment, and can be implemented in a different manner as appropriate within the scope of the present invention.
For example, as the intermediate fixing tool and the connecting tool, those having different modes can be appropriately used depending on the kind of the existing tension material and the tension material used for the widened portion.

FIG. 7 is a side view, a front view, and a plan view showing another example of an intermediate fixing tool that can be used in the floor slab widening method of the present invention.
As in the intermediate fixing tool 10 shown in FIG. 5, the intermediate fixing tool 30 is formed by combining a fixing block 31 composed of two halved blocks 32 and 33 and two halved blocks 32 and 33 together. A plurality of bolts 34 which are coupling means are provided. And the hollow hole 35 which penetrates the tension material 3 is formed in the junction part of the two half blocks 32 and 33. As shown in FIG. The means for fixing the fixing block 31 to the tension member 3 inserted into the hollow hole 35 is a filler 36 filled in the hollow hole 35 in this example. As the filler 36, mortar or the like can be used. Since the inner diameter of the hollow hole 35 is reduced in the direction A in which the tendon 3 is pulled, a compressive force is applied from the inner peripheral surface of the hollow hole 35 toward the center of the tendon 3 when the tendon 3 is pulled. It acts and firmly holds the tendon 3.
The inner diameter of the hollow hole 35 may be uniform in the axial direction of the tendon 3, but in this case, it is desirable to use an expansible filler. The tendon is strongly held by the compression force generated by restraining the expansion that occurs at the time of curing after filling.

FIG. 8 is a cross-sectional view showing another example of a connection tool that can be used in the floor slab widening method of the present invention.
This connecting tool 40 is made of a bundle of steel wires having an outer diameter of about 5 mm to 8 mm used as the tension member 7 disposed on the existing floor slab, and made of steel as the tension member 8 disposed on the floor slab of the widened portion. It can be employed when lines are used.
The connecting tool 40 is attached to each of a steel block 41 to which each steel wire 7a of the tension member 7 arranged on an existing floor slab is coupled, and a steel wire insertion hole provided in the steel block 41. A wedge 42 for fixing the steel wire 7a to the steel block 41, a rod 43 connected to the steel block 41, and a cylindrical member connected to the rod 43, wherein the tension member 8 of the widened portion is coupled. The main part is composed of a steel sleeve 44 and a wedge 45 for fixing the tension member 8 of the widened portion inserted into the hollow hole of the steel sleeve 44.

The steel block 41 has a number of steel wire insertion holes corresponding to the number of the steel wires 7a, and each of the steel wires 7a is inserted between the inner peripheral surface of the steel wire insertion hole and the steel wire 7a. The steel wire 7 a is joined to the steel block 41 by inserting the wedge 42.
The rod 43 is coupled by screwing a male screw portion provided on one end side into a female screw portion provided on the steel block 41. The male screw portion on the other end side of the rod 43 is screwed into the female screw portion formed in the hollow hole of the steel sleeve 44 and connected to the steel sleeve 44.
The hollow hole of the steel sleeve 44 has an inner diameter that decreases toward the end face on the side where the floor slab is widened. A wedge 45 is inserted between the inner peripheral surface of this portion and the tension member 8 inserted into the hollow hole, and the steel sleeve 44 and the tension member 8 of the widened portion are joined.
In addition, the code | symbol 47 in FIG. 8 is a pressing plate which suppresses that the wedge 42 slips out from a steel wire penetration hole via the spring 46. FIG.

  As shown in FIG. 8, when a steel strand is used as the tension member 8 disposed in the widened portion, so-called untwisting occurs in which twisting of the strand of the steel is eased by introduction of the tension force, and the connecting device 40 May rotate around the axis of the tendon 8. When the force to rotate from the steel strand is transmitted, the portion where the rod 43 and the steel sleeve 44 are twisted together, or the portion where the rod 43 and the steel block 41 are twisted are loosened, or existing tension members A plurality of steel wires 7a included in 7 may be twisted. A rotation restraining member for preventing this is provided. The rotation restraining member includes a first rectangular tube member 48 fixed to the steel sleeve 44 and a second rectangular tube member 49 fixed to the concrete of the floor slab. The first rectangular tube member 48 is a second one. Is inserted inside the square member 49. Thereby, while permitting the connection tool 40 and the concrete of the floor slab to move relatively in the axial direction of the tension material 8, and restraining the connection tool 40 from rotating around the axis line of the tension material 8. It has become.

On the other hand, in the above-described embodiment, the concrete floor slab is widened so as to extend, but the invention is not limited to such a widening of the floor slab. When it becomes larger, the floor slab can be widened in the manner shown in FIG.
In the example shown in FIG. 9A, a rib 52 having a thickened or partially thickened rib 52 is provided on the lower side of the widened slab 51 for reinforcement. Further, as shown in FIG. 9B, the floor slab 53 widened by the diagonal support member 54 can be supported from the lower portion of the girder 55 adjacent to the overhanging portion. Further, in the example shown in FIG. 9C, the floor slab 50 is widened by adding a girder 57 together with the floor slab 56.

1: main girder, 2: floor slab, 2a: existing floor slab, 2b: widened portion of floor slab, 3: existing tension material, 4: tension material in widened portion, 5: existing anchorage, 6: widening Partial fixing device, 7: Existing tension material, 8: Widening area tension material,
10: Intermediate fixing tool, 11: First half block, 12: Second half block, 13: Fixing block, 14: Bolt, 15: Wedge, 16: Hollow hole, 17: Bolt hole, 18: Bolt Hole,
20: connector, 21: female cone, 22: male cone, 23: nut, 24: bearing plate, 25: coupler, 26: tension rod, 27: center hole jack, 28: jack chair,
30: Intermediate fixing tool, 31: Fixing block, 32: First half block, 33: Second half block, 34: Bolt, 35: Hollow hole, 36: Filler
40: connector, 41: steel block, 42: wedge, 43: rod, 44: steel sleeve, 45: wedge, 46: spring, 47: retainer plate, 48: first square tube member, 49: second Square tube members,
50: Existing floor slab, 51: Widened floor slab, 52: Rib, 53: Widened floor slab, 54: Diagonal support material, 55: Girder, 56: Widened floor slab, 57: Expanded girder

Claims (3)

A method of widening a concrete floor board in which tendons are arranged in the width direction of the bridge and prestress is introduced,
The tension material is positioned away from the fixing end fixed in the vicinity of the side end on the widening side in the axial direction of the tension material, and within a range in which the tension force of the tension material can be maintained. Suspending the concrete of the floor slab at a position close to the fixing end to expose the tendon;
Attaching an intermediate fixing tool to the exposed tendon;
Placing the concrete for backfilling into the portion of the floor slab sandwiched with concrete, embedding the intermediate fixing tool and fixing the concrete floor slab integrally;
Suspending the concrete covering the fixing end on the side where the tendon material is widened, removing the existing fixing tool, and exposing the length at which the connecting tool at the end of the tendon material can be attached;
Attaching a connecting tool to the tendon and connecting an extension tendon;
Continuous with the floor slab, placing concrete in the widened portion of the floor slab, and
And a step of introducing a prestress into the concrete of the widened portion by introducing a tension force to the extending tension material after the cast concrete of the widened portion is hardened. The connector is a cylindrical female cone into which the tension material is inserted into a hollow hole, and a wedge-shaped insertion between the inner peripheral surface of the hollow hole of the female cone and the outer peripheral surface of the tension material. A male cone and a nut to be twisted together with a male screw formed on the outer peripheral surface of the female cone;
Gripping the female cone to tension the tendon, and introducing tension from the intermediate anchor to the connector;
The method for widening a floor slab according to claim 1, further comprising the step of rotating the nut and fixing the tendon through the connector. A plurality of the tendon members are arranged at predetermined intervals in the axial direction of the bridge,
The step of exposing the tension material by pulling the concrete of the floor slab is performed every other one of the plurality of tension materials,
The step of attaching the intermediate fixing tool and the step of placing the concrete for backfilling are performed, and after the concrete for backfilling is hardened, the step of exposing the adjacent tendon is performed. A method for widening a floor slab according to claim 1 or claim 2.

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