JP7186669B2 - Concrete floor slab and method for repairing concrete floor slab - Google Patents

Description

The present invention relates to a concrete floor slab formed by arranging precast concrete slabs on a bridge girder, particularly a concrete floor slab that facilitates replacement of a part of the precast slabs, and a precast that constitutes the concrete floor slab. It relates to a method of replacing part of a plate.

A plurality of precast slabs arranged in the axial direction of the bridge girder and integrally connected to each other are widely used as the concrete floor slab formed on the bridge girder. Then, prestress is introduced in the axial direction of the bridge girder so that the precast slabs are firmly integrated.

Concrete floor slabs formed in this manner may be damaged due to aged deterioration or the like. A damaged concrete floor slab needs to be repaired to restore its function, and the damaged part is replaced with a precast slab. However, in a concrete slab in which prestress is introduced in the axial direction of the bridge girder, a continuous tendon is embedded over multiple precast slabs. Moreover, cutting the prestressing tendon to remove some of the precast plates may release the prestress over a wide area. For this reason, when trying to replace the precast plate, a wide range must be replaced at the same time, requiring a lot of work and cost.

Under these circumstances, Patent Literature 2 discloses a concrete floor slab that assumes that a part of the precast slab will be replaced later.
This concrete floor slab is formed by arranging a plurality of panels made of precast concrete on a girder, and a panel group for tension fixation consisting of three panels is provided for each span of the bridge. The tension fixing panel group is composed of two fixing panels and one connection panel arranged between them, and a plurality of normal panels are arranged between the plurality of tension fixing panel groups. The prestressing tendons are connected by connectors and are tensioned sequentially, but by introducing a continuous prestress to the series of normal panels and the two anchored panels adjacent on either side thereof, to the ends of these. Fixture is installed. Thus, when the connecting panel is removed, the prestressing of the anchoring panel and the normal panel on either side of it is maintained. This permits the removal and replacement of the connecting panel of two tension anchoring panel groups and the removal and replacement of the two connecting panels and the series of normal panels between them and the adjacent anchoring panel. It's becoming

JP-A-07-102529 JP-A-07-268808

However, the conventional technique described above has the following problem that needs to be solved.
When a portion of a panel made of precast concrete is damaged and is to be replaced, at least two fixed panels, two connecting panels and a series of normal panels between the two fixed panels must be replaced. must. For this reason, it is not possible to sufficiently meet the demand for reducing repair costs by minimizing the number of panels to be replaced. In addition, when the concrete floor slab is installed, it is necessary to provide the fixing panel with a block for fixing the cap cable in advance. The cap cable is used to introduce prestress to the tension anchoring panel group after replacing the panels, and an unused anchoring block is provided when the concrete floor slab is installed.

The present invention has been made in view of the above circumstances, and can easily repair even if the number of damaged precast plates that need to be replaced is small or large. It is an object of the present invention to provide a concrete floor slab and to provide a method for repairing this concrete floor slab.

In order to solve the above problems, the invention according to Claim 1 provides a concrete floor in which a plurality of precast plates are arranged on a bridge girder, and prestress is introduced in the axial direction of the bridge girder to join the plurality of precast plates. A plate, wherein the tendon for introducing the prestress is an FRP member in which a plurality of fibers that are continuous in the axial direction are bound with a synthetic resin, and each of the precast plates is attached to another concrete member. A joining reinforcing bar that can be partially embedded and used for joining is embedded over the entire length of the joining reinforcing bar, and the joining reinforcing bar is located near the joint end with the adjacent precast slab in another concrete member. To provide a concrete floor slab having a fixing reinforcing part that strengthens the fixing function to the concrete member when embedded in a concrete member.

In this concrete floor slab, each of the precast slabs is embedded with reinforcing bars for joining, and some of the precast slabs need to be replaced. The joining reinforcing bar can be exposed by pinching the part. Another newly installed reinforcing bar is superimposed on this joining reinforcing bar, and concrete is poured so as to bury the overlapped portion of this newly installed reinforcing bar and joining reinforcing bar. It is possible to firmly join the remaining concrete slab and the remaining precast slab. The newly installed concrete slab is preferably a new precast slab, but may be a concrete slab formed by placing uncured concrete on the bridge girder.
In addition, in this concrete floor slab, since FRP members are used as tendons that introduce prestress in the axial direction of the bridge girder, the adhesion to the concrete is good, and the precast slab that needs to be replaced has been removed. At the same time, the reduction in the prestress of the precast plate that remains even after cutting the FRP member, which is the tendon, is suppressed to a small and limited range.

The invention according to claim 2 is directed to the concrete floor slab according to claim 1, wherein the reinforcement fixing portion of the joining reinforcing bar is processed to be curved in an arc or parabolic shape, and the curved portion is the precast slab. It shall be continuous with the straight portion embedded in the axial direction of the bridge girder along the upper and lower surfaces.

In this concrete floor slab, it is possible to easily pull out the curved and looped connecting reinforcing bars. Then, the loop-shaped reinforcing bars protruding from the new precast plate placed at the adjacent position or the loop-shaped reinforcing bars embedded in the concrete placed at the adjacent position are superimposed, and the new precast plate or cast-in-place It becomes possible to join firmly with the concrete slab formed by the installation.

The invention according to claim 3 is the concrete floor slab according to claim 1, wherein the anchoring reinforcement part is a joining reinforcing bar embedded in the axial direction of the bridge girder along the upper surface and the lower surface of the precast slab, respectively, It is assumed that the cross section is enlarged near the joint end with the adjacent precast plate.

In this concrete floor slab, the reinforcing bar for joining has an enlarged cross-sectional portion, so that even if the portion that has been scraped out is short, it is firmly fixed to the newly placed concrete. Therefore, the rebar protruding from the new precast slab placed at the adjacent position or the rebar embedded in the concrete poured at the adjacent position is overlapped, and the remaining precast slab is replaced with the new precast slab or cast-in-place. It becomes possible to join firmly with the concrete slab formed by

The invention according to Claim 4 is the concrete floor slab repair method according to any one of Claims 1 to 3, wherein a precast slab that needs to be replaced is removed from the arranged precast slabs. cutting the FRP member at the boundary between the precast slab to be removed and the precast slab to remain; a step of exposing the anchorage reinforcing portion of the reinforcing bar for the bridge, a joining reinforcing bar exposed from the remaining precast plate, and a new joining reinforcing bar arranged so as to overlap the joining reinforcing bar in the axial direction of the bridge girder. To provide a method for repairing a concrete floor slab, comprising the step of placing uncured concrete in a slab and forming a new concrete slab continuous with the remaining precast slab.

In this concrete floor slab repair method, even if the precast slab that needs to be replaced is removed, the reduction in prestress introduced into the precast slab that remains at the adjacent position can be suppressed to a small extent. In addition, by scraping off part of the remaining precast slab, the exposed reinforcing bars for joining are used to firmly connect the concrete slab made of the replaced new precast slab or the new concrete slab formed by placing the concrete on site. It becomes possible to join.

The invention according to claim 5 is the method for repairing a concrete floor slab according to claim 4, wherein the step of forming a new concrete floor slab comprises forming a new precast slab, the end face of which is joined to the remaining precast slab. A step of installing a new precast plate from which a new joining reinforcing bar for joining with the remaining precast plate protrudes from the bridge girder at a position where the replaced precast plate has been removed; Concrete for connection is placed and hardened in the space where the connecting reinforcing bars exposed from the remaining precast plate and the new connecting reinforcing bars protruding from the new precast plate overlap in the axial direction of the bridge girder. and

In this method of repairing concrete slabs, the precast slab that needs to be replaced can be removed and quickly replaced with a new precast slab with protruding rebars for new joining, and the new precast slab can be firmly connected to the new precast slab. becomes possible.

The invention according to claim 6 is the concrete floor slab repair method according to claim 5, wherein connecting concrete is placed between the new precast slab and the remaining precast slab. Before that, a prestress in the axial direction of the bridge girder was introduced by the tension force of the new tendon penetrating the new precast slab, and concrete was poured into the joint between the remaining precast slab and the new precast slab. After hardening, part or all of the new prestressing tendon shall be released.

In this concrete floor slab repair method, prestress can also be introduced to the joint between the remaining precast slab and the new precast slab. That is, the new precast slab shrinks by introducing a prestress to it before pouring the connecting concrete. Then, when the tension of the new tendon is released after the concrete placed in the joint has hardened, the elongation of the new precast slab is restrained by the remaining precast slab adjacent to it, and prestress is introduced to the joint. be done.

The invention according to claim 7 is the concrete floor slab repair method according to claim 6, wherein the release of the tension of the new prestressing tendon is a notch exposing a part of the new prestressing tendon to the new precast slab. is formed in advance, and the new prestressing tendon is cut within the notch.

In this repair method, the tension can be released by the simple work of cutting the newly installed prestressing tendon, and prestress can be introduced to the joint between the remaining precast floor slab and the new precast floor slab.

As described above, the concrete floor slab of the present invention can be easily repaired whether the number of damaged precast slabs is small or large. In addition, the repair method of the present invention makes it possible to efficiently repair damaged concrete floor slabs at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic perspective view which shows the structure of the bridge which has a concrete deck of this invention. 1 is a schematic side view showing an example of a bridge having a concrete floor slab of the present invention, and a sectional view of the concrete floor slab of the present invention; FIG. FIG. 3 is a schematic diagram showing a process of replacing a part of a precast slab that constitutes the concrete floor slab shown in FIG. 2 ; FIG. 10 is a schematic cross-sectional view showing another example of the state after part of the precast plate is replaced; FIG. 4 is a schematic diagram showing a process of introducing prestress to a joint between a remaining precast plate and a new precast plate after part of the precast plate is replaced. FIG. 10 is a schematic diagram showing another example of a process of introducing prestress to a joint between a remaining precast plate and a new precast plate after part of the precast plate is replaced; FIG. 10 is a schematic diagram showing another example of a process of introducing prestress to a joint between a remaining precast plate and a new precast plate after part of the precast plate is replaced; FIG. 4 is a cross-sectional view showing another example of the concrete floor slab of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic perspective view showing the construction of a bridge having a concrete floor slab of the present invention. Moreover, FIG. 2 is a schematic side view showing an example of a bridge having the concrete floor slab of the present invention, and a sectional view of the concrete floor slab of the present invention.
This bridge is used as a road bridge, and precast slabs 10 are arranged on bridge girders 1 supported by abutments or bridge piers 2 and 3. and Each precast slab 10 is provided with a plurality of ducts 12 in the axial direction of the bridge girder 1, and the tendons inserted through these are tensioned and fixed to the concrete floor slab 11 in the axial direction of the bridge girder 1. Prestress is introduced.

The bridge girder 1 is constructed by connecting a plurality of steel girders 4 in parallel and connecting them with horizontal girders 5. Each steel girder 4 has an upper flange 6, a lower flange 7, and a web connecting them vertically. 8. An anti-slip member 9 for fixing the precast plate is provided on the upper surface of the upper flange.

The precast slab 10 is formed by pouring concrete in a factory, production yard, or the like in advance, and has a predetermined dimension in the axial direction of the bridge girder 1 . In addition, the dimension in the direction perpendicular to the axis of the bridge girder corresponds to the width of the road. These precast slabs 10 are provided with reinforcing bars so as to withstand the wheel load and the like acting when the concrete floor slabs 11 are formed on the bridge girders. Moreover, the prestress may be introduced in a direction perpendicular to the axis of the bridge girder 1, and the prestress may be introduced by either a pretension method or a posttension method.

These precast plates 10 are arranged on the bridge girder in the axial direction of the bridge girder, connected and fixed to the steel girder 4 by anti-slip members 9 . Adjacent precast plates may be joined by a synthetic resin adhesive or the like, or the precast plates are arranged with a gap of about 10 mm to 40 mm and the space between them is filled with non-shrink mortar. may be combined.

As shown in FIG. 2(b), the precast slab 10 has a plurality of joining reinforcing bars 31 arranged in the axial direction of the bridge girder 1, and these are arranged at predetermined intervals in the width direction of the bridge girder 1. In addition, horizontal reinforcing bars 32 are arranged at predetermined intervals in a direction perpendicular to the bridge girder. The joining reinforcing bars 31 are arranged in the axial direction of the bridge girder 1 along the upper and lower surfaces of the precast slabs 10, and are curved in an arc or parabolic shape near the joining end surfaces of the adjacent precast slabs. The fixing reinforcing portion 31b is processed, and the fixing reinforcing portion 31b is continuous with the straight portions 31a arranged in the vicinity of the upper surface and the lower surface. These joining reinforcing bars 31 are embedded in each precast plate 10 over the entire length and are not used for joining the precast plates 10 . However, it can be used when joining adjacent precast plates together. In other words, when the curved fixing reinforcement portion 31b protrudes from the precast plate, the joining reinforcing bars protruding from the two precast plates to be joined are arranged so that their positions in the axial direction of the bridge girder overlap each other. The two precast plates can be firmly joined by placing connecting concrete between the two precast plates so as to embed the two. At this time, the reinforcing fixing portion 31b processed to be curved functions so as to be firmly fixed even if the length embedded in the connecting concrete placed in the joint portion is small.

The tendon 13 that introduces prestress in the axial direction of the bridge girder to the precast slab 10 uses an FRP rod in which high-strength fibers are bound with a synthetic resin. Aramid fiber, carbon fiber, mineral fiber, etc. can be used as the high-strength fiber, and a bundle of a plurality of fibers bundled together, a bundle of a plurality of fibers twisted together, a bundle of a plurality of fibers can be used in combination in the form of a braid.

A tendon 13 is placed in a duct 12 provided in each precast plate. These ducts 12 are provided so as to communicate in the axial direction of the bridge girder 1 when the precast plates 10 are arranged on the bridge girder 1 . Then, for each predetermined number of precast slabs 10, for example for each span of the bridge girder 1, a tendon 13 can be inserted into the duct 12, tensioned and anchored to introduce prestress into the series of precast slabs. .

The duct 12 has openings in the fixing protrusions 14 provided for each predetermined number of precast plates, and the tendons 13 can be inserted through these openings. Then, it is fixed to the precast plate 10 by being tensioned at the end face that has passed through a predetermined number of precast plates. A plurality of tendons 13 arranged in the axial direction of the bridge girder 1 partially overlap each other. That is, the tendon 13-1 inserted into the duct from the fixing protrusion 14-1 shown in FIG. The inserted tendon 13-2 overlaps with the precast plate 10a. The prestress of the concrete floor slab 11 is introduced so as to be continuous in the axial direction of the bridge girder 1 by repeating the tensioning and fixing of the plurality of tendons 13 arranged in this manner.
After the tension force is applied to the tendon 13, the grout material is injected into the duct 12 and hardened to join the tendon 13 and the precast plate 10 together. Mortar or the like is filled between the anti-slip member 9 fixed to the steel girder 4 and the precast plate, and the precast plate is fixed to the bridge girder 1 .

When a part of the concrete floor slab 11 as described above is damaged, it can be repaired by replacing the damaged part of the precast slab 10 .
Replacing the precast plate 10 can be done as follows.
As shown in FIG. 3(a), the damaged precast plate 10-1 is removed leaving the remaining precast plate 10-2. Then, the end portion of the precast plate 10-2 to be left adjacent to the removed precast plate 10-1 is pinched off, and the fixing reinforcement portion 31b of the joining reinforcing bar 31 embedded in the remaining precast plate 10-2 is removed. expose. Along with this, the tendon 13 arranged in the axial direction of the bridge girder 1 is cut and removed. The tendon 13 is connected to the precast plate 10 by the hardened grout material in the duct 12, and the tension of the cut tendon 13 is slightly longer than the cut end because of the good adhesion performance of the FRP rod. Well, the tension is only released in the range of about 200mm to 400m. Therefore, the prestress introduced into the remaining precast plate 10-2 is maintained except for a limited range near the cutting position.

Subsequently, as shown in FIG. 3(b), a new precast plate 10-3 is installed at the position where the precast plate to be replaced was removed. The new precast slab 10-3 has a newly installed joining reinforcing bar 33 projecting in the axial direction of the bridge girder 1 from the end face. The new joining reinforcing bar 33 has the same shape as the joining reinforcing bar 31 protruding from the remaining precast plate 10-2, and has a loop-shaped curved portion from a straight portion near the upper surface and a straight portion near the lower surface. It is continuous with the shape part. The newly installed joining reinforcing bars 33 are arranged so that the joining reinforcing bars 31 protruding from the remaining precast slab 10-2 overlap with each other in the axial direction of the bridge girder.

The looped portions of the joining reinforcing bars 31 protruding from the remaining precast slab 10-2 and the new precast slab 10-3 and the newly installed joining reinforcing bars 33 overlap, and the area surrounded by these overlaps. As shown in 3(c), the connecting portion lateral rebars 34 are arranged in the direction along both end faces. Then, connecting concrete 28 is placed so as to bury these joining reinforcing bars 31 , new joining reinforcing bars 33 , and connecting portion lateral reinforcing bars 34 . The precast slab 10-2 that remains after the placed concrete hardens and the new precast slab 10-3 that has been replaced are firmly joined together, and the damaged portion of the concrete floor slab 11 is repaired.

In the concrete floor slab 11 repaired in this way, prestress is not introduced to the new precast slab 10-3 and the joints between the new precast slab 10-3 and the remaining precast slab 10-2. As a reinforced concrete member, it resists the cross-sectional force in the axial direction of the bridge girder 1 .
A fiber reinforcing sheet 27 is attached to the underside of the concrete floor slab 11 in order to reinforce the portion where no prestress has been introduced after such repair. The fiber-reinforced sheet 27 can be a sheet woven from high-strength fibers such as aramid fibers and carbon fibers, and can be attached using a synthetic resin adhesive such as epoxy resin. The range where this fiber reinforced sheet 27 is attached includes the joints between the new precast plate 10-3 and the remaining precast plate 10-2, and the tendons 13 arranged on the remaining precast plate 10-2. It is desirable to extend the range where the tension is released, that is, the range of length required for fixing the tendon 13 from the cut end of the tendon 13 .

The repair of the concrete floor slab shown in FIG. 3 is to replace one precast slab, but the repair to replace a plurality of continuous precast slabs can be performed as follows.
After removing a plurality of continuous precast plates, the remaining precast plate 10-4 and the new precast plate 10-5 can be joined together in the same manner as the process shown in FIG. Then, as shown in FIG. 4( a ), new joints curved in a loop shape projecting from each of the new precast plates 10 - 5 are also used for the joints between the new precast plates 10 - 5 and 10 - 5 . Reinforcing bars 35 can be used. These new joining reinforcing bars 35, 35 are arranged so that the positions in the axial direction overlap between the adjacent new precast plates 10-5, 10-5. Then, concrete floor slabs are placed so as to be continuous with precast slabs 10-4 where a plurality of new precast slabs 10-5 remain by placing connecting concrete 29 between both precast slabs so as to embed them. can be repaired.

Further, when replacing a plurality of precast plates, as shown in FIG. 4(b), the new precast plates 10-6 are tightened by a new tension member 15 penetrating the new precast plates 10-6, and the new precast plates 10-6 are tightened. It can also be joined. Both end surfaces of the new precast plates 10-6 and 10-6 to be joined at this time are substantially vertical surfaces, and the adhesive layer or It can be joined through a non-shrinkage mortar layer. Also, the new precast plate 10-6 and the remaining precast plate 10-7 can be joined in the same manner as in the process shown in FIG.
In the new precast plate 10-6, it is desirable to embed a joining reinforcing bar 36 having a loop-shaped anchoring reinforcing portion near the end face where the new precast plates are joined together over the entire length. As a result, when repair is required again after repair, it is possible to select an arbitrary precast plate and replace it.

In the concrete floor slab repaired as shown in FIG. 4(b), prestress is introduced into the new precast slab 10-6, but the new precast slab replaced with the remaining precast slab 10-7. No prestress was introduced at the junction with 10-6. Also, as shown in Fig. 3 or Fig. 4(a), even in the repaired concrete floor slabs, prestress was not introduced to the new precast slabs and the joints between the new precast slabs and the remaining precast slabs.
In order to introduce prestress to the new precast plate and the junction between the new precast plate and the remaining precast plate, the following means can be adopted.

As shown in FIG. 5(a), the precast plate requiring repair is removed and a new precast plate 10-8 is placed to replace it. Then, a plurality of new precast plates 10-8 are joined by a plurality of newly installed tendons 16, both ends of which are fixed to the new precast plates 10-8, and prestress in the axial direction of the bridge girder is introduced. After that, as shown in FIG. 5(b), connecting concrete 17 is placed at the joint between the remaining precast plate 10-9 and the new precast plate 10-8 to join them together. After the connecting concrete 17 has hardened, the new tendons 16 are partially or wholly released from tension. The tension is released by, for example, cutting the new tendon 16 within a notch 18 provided to expose the intermediate portion of the new tendon 16 as shown in FIG. 5(b). be able to.

The new precast slab 10-8, to which prestress has been introduced by the tension of the newly installed prestressing member 16, is restrained in elongation by the remaining precast slab 10-9 even if the tension is released. This introduces prestress between the new precast plate 10-8 and the remaining precast plate 10-9.

The introduction of prestress and release of tension in the new precast plate can also be done as follows.
As shown in FIG. 6(a), fixing protrusions 19 are provided at both ends of the arranged new precast plates 10-10, and a plurality of ducts penetrating the new precast plates 10-10 are It is assumed that the fixing protrusions 19 are open at both ends. A new prestressing member 20 inserted through these ducts is tensioned to introduce prestress to the new precast plate 10-10. Then, after placing and joining the connecting concrete 21 between the new precast plate 10-10 and the remaining precast plate 10-11, the fixing of the tendon is released by the fixing protrusion 19. can be done.

As a method of introducing prestress to the new precast plate and the joint between the new precast plate and the remaining precast plate, the following means can be employed.
In this method, tendon fixing protrusions 22 are provided at both end portions of a plurality of new precast plates 10-12 arranged as shown in FIG. 7(a). The other end of the duct 23, one end of which is open at these fixing protrusions 22, is opened at the end face of the other end side of the arranged new precast plates 10-12. On the other hand, on the end faces of the remaining precast plates 10-13 where the joining reinforcing bars 36 are exposed, there are anchor holes for the tendons in the horizontal direction corresponding to the positions where the ducts 23 open on the end faces of the new precast plates 10-12. 24 is drilled.

After removing the precast plate to be replaced and arranging the new precast plate 10-12, a new tendon 25 is inserted into the duct 23 provided in the new precast plate 10-12 as shown in FIG. . The new tendon 25a is inserted through the opening of the fixing protrusion 22a provided at one end of the arranged new precast plate 10-12, and is left through the new precast plate 10-12. The tip is inserted into the anchor hole 24a formed in the end face of the plate 10-13. Then, the anchor hole 24a is filled with a synthetic resin-based adhesive such as an epoxy resin, and the new tendon 25a is fixed. In addition, the new tendon 25b is also inserted through the opening of the fixing protrusion 22b provided near the other end of the new precast plate 10-12, and similarly penetrates the new precast plate 10-12 to the opposite side. The remaining precast plate 10-13 is inserted into the anchor hole 24b and fixed.
If an FRP rod is used as the new tendon 25, the fixing performance to the anchor holes 24a and 24b is improved, and the cutting length of the anchor holes 24a and 24b can be reduced.

After that, between the remaining precast plate 10-13 and the new precast plate 10-12, as shown in FIG. The remaining precast slab 10-13 and the new precast slab 10-12 are joined by casting concrete 26 for connection. After the cast connecting concrete 26 hardens, tension is applied to the new tendons 25a and 25b to fix them to the fixing protrusions 22a and 22b. As a result, prestress can be introduced to the joint between the remaining precast plate 10-13 and the new precast plate 10-12 and to the new precast plate 10-12.
This method can also be used in combination with the prestress introducing method shown in FIGS.

FIG. 8 is a cross-sectional view showing part of a concrete floor slab 41 that is another embodiment of the present invention.
In this concrete floor slab 41, the structure of the joining reinforcing bars 42 embedded in the precast slab 40 is different.
The joining reinforcing bars 42 are arranged along the upper surface and the lower surface of the precast plate 40, respectively, and have cross-sectional enlarged portions 42a in the vicinity of the joining end surfaces of the adjacent precast plates. The cross-sectional enlarged portion 42a functions as a fixing reinforcing portion. The cross-sectionally enlarged portion 42a can be formed, for example, by mechanically deforming the main body portion of the joining reinforcing bar 42 in a high temperature state or a normal temperature state. It can also be formed by joining steel plates or the like by welding. Welding can also be carried out by rotating a steel plate or reinforcing bar around the axis of the reinforcing bar at high speed, heating it to a high temperature, and pressing it.

In such a concrete floor slab, part of the precast slabs can be easily replaced in the same manner as the concrete floor slab shown in FIG. Since the joining reinforcing bar 42 has the enlarged cross-section portion 42a, the pull-out resistance from the connecting concrete placed at the joining portion between the remaining precast slab and the new precast slab increases. As a result, even if the length of the joint embedded in the concrete is short, the joining reinforcing bar is firmly fixed, and the remaining precast slab and the new precast slab are firmly joined.

The concrete floor slab and the concrete floor slab repair method described above are embodiments of the present invention, and the present invention is not limited to these embodiments. can be designed and implemented in other forms.
For example, in the repair method of the above embodiment, a new precast slab is used as the concrete slab that is formed after removing the precast slab to be replaced. It may be something to do. It can be effectively applied especially when there are few precast plates to be replaced. In this case, after the new joining reinforcing bars are placed so as to overlap the joining reinforcing bars that have been pulled out from the remaining precast slab, the concrete that forms the concrete slab can be cast so as to be in close contact with the remaining precast slab. .
Further, the bridge girders supporting the concrete floor slab of the present invention are not limited to those using steel girders having an I-shaped cross section as shown in FIG. , can be applied to floor slabs in which precast concrete slabs are used.
In addition, the arrangement of reinforcing bars, the arrangement of tendons, the arrangement intervals, etc. of the precast plate can be appropriately designed.

1: Bridge girder, 2: Pier, 3: Pier, 4: Steel girder, 5: Cross girder, 6: Upper flange, 7: Lower flange, 8: Web, 9: Anti-slip member,
10: Precast plate, 10-1: Precast plate to be removed for replacement, 10-2: Precast plate to remain, 10-3: New precast plate, 10-4: Precast plate to remain, 10-5: New Precast version, 10-6: New precast version, 10-7: Remaining precast version, 10-8: New precast version, 10-9: Remaining precast version, 10-10: New precast version, 10-11: Remaining precast version, 10-12: New precast version, 10-13: Remaining precast version,
11: Concrete floor slab, 12: Duct, 13: Tendon, 14: Fixing projection, 15: New tendon, 16: New tendon, 17: Concrete for connection, 18: Notch for exposing tendon, 19: Fixing projection, 20: New tendon, 21: Concrete for connection, 22: Fixing projection, 23: Duct, 24: Anchor hole, 25: New tendon, 26: Concrete for connection, 27: Fiber Reinforcing sheet, 28: Concrete for connection, 29: Concrete for connection,
31: joining reinforcing bars, 31a: straight portion of joining reinforcing bars, 31b: anchoring and strengthening part of joining reinforcing bars, 32: lateral reinforcing bars, 33: newly installed joining reinforcing bars, 34: lateral reinforcing bars at connecting portion, 35: newly installed Joining reinforcing bar, 36: New joining reinforcing bar, 37: New joining reinforcing bar,
40: Precast plate, 41: Concrete floor slab, 42: Reinforcement for joining, 42a: Enlarged section of rebar for joining

Claims (7)

A concrete floor slab in which a plurality of precast slabs are arranged on a bridge girder and prestress is introduced in the axial direction of the bridge girder to join the plurality of precast slabs,
The tendon for introducing the prestress is an FRP member in which a plurality of fibers continuous in the axial direction are bound with a synthetic resin,
In each of the precast plates, a joining reinforcing bar that can be partially embedded in another concrete member and used for joining is embedded over the entire length of the joining reinforcing bar,
The reinforcing bar for joining has, near the joint end with the adjacent precast slab, a fixing reinforcing part that strengthens the fixing function to the concrete member when embedded in another concrete member. Concrete floor slabs. The fixing reinforcing portion of the joining reinforcing bar is processed to be curved in an arc or parabolic shape, and the curved portion is a straight portion embedded in the axial direction of the bridge girder along the upper and lower surfaces of the precast plate. The concrete floor slab according to claim 1, characterized in that it is continuous. The reinforcing anchoring portion is formed by enlarging the cross section of the joining reinforcing bars embedded in the axial direction of the bridge girder along the upper and lower surfaces of the precast plates near the joint ends with the adjacent precast plates. The concrete floor slab according to claim 1, characterized by: A concrete floor slab repair method according to any one of claims 1 to 3,
A step of removing the precast plates that need to be replaced among the arranged precast plates and cutting the FRP member at the boundary between the precast plates to be removed and the remaining precast plates;
A step of pinching off the joint end portion of the remaining precast plate facing the removed precast plate to expose the fixing and strengthening portion of the joining reinforcing bar;
Unhardened concrete is placed so as to bury the joining reinforcing bars exposed from the remaining precast plate and the new joining reinforcing bars arranged so as to overlap with the joining reinforcing bars in the axial direction of the bridge girder, and the remaining and forming a new concrete slab continuous with the precast slab. The process of forming a new concrete floor slab is
A new precast slab, which has a new joining reinforcing bar for joining with the remaining precast slab protruding from the end face to be joined with the remaining precast slab, a new precast slab to be replaced on the bridge girder. A step of installing at the removed position;
Between the remaining precast slab and the new precast slab, connecting reinforcing bars exposed from the remaining precast slab and new joining reinforcing bars protruding from the new precast slab overlap in the axial direction of the bridge girder. 5. The method for repairing a concrete floor slab according to claim 4, further comprising the step of placing and hardening the concrete. In the new precast plate, before placing connecting concrete between the remaining precast plate and the new precast plate, the tension of the new tendon penetrating the new precast plate is used to move the bridge girder in the axial direction. We have introduced a prestress of
6. The method according to claim 5, wherein concrete is placed at the joint between the remaining precast slab and the new precast slab, and after the concrete has hardened, the tension of part or all of the new tendon is released. method for repairing concrete floor slabs. The release of the tension of the new tendon is performed by forming a notch in the new precast plate in which a part of the new tendon is exposed, and cutting the new tendon in the notch. The method for repairing a concrete floor slab according to claim 6, characterized in that:

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