Method for repairing bridge girder

Abstract

To easily repair an end part of a bridge girder in a method for repairing the bridge girder.SOLUTION: A method for repairing the end part of a bridge girder 3 in the bridge axial direction supported by an abutment 2 having a parapet 6 provided on the upper surface thereof includes an excavation step (FIG. 2) of excavating an earthwork part 8 disposed on the back surface side of the abutment 2 and the back surface side of the parapet 6, and a removal step (FIG. 3) of removing an existing expansion / contraction device 14 connecting the parapet 6 and the end part of the bridge girder 3, and at least a part of the parapet 6 after the excavation step. The method for repairing the end part of the bridge girder 3 includes a repairing step of repairing the end part of the bridge girder 3 after the removing step, a constructing step (FIG. 8) of constructing the support part 32 for supporting a new expansion / contraction device 33 and the new expansion / contraction device 33 on the abutment 2 after the repairing step, and a backfilling step (FIG. 10) of backfilling the earthwork part 8 to the back surface side of the abutment 2 and the back surface side of the support portion 32 after the constructing step.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a method for repairing the end of a bridge girder supported by a bridge abutment.

Background Art

[0002] In a bridge girder of a bridge having a concrete floor slab, the floor slab is damaged by rainwater, antifreeze agents sprayed in cold regions, etc. As a construction method for repairing the damaged floor slab, Patent Document 1 discloses a method for repairing the lower surface of the end of a concrete floor slab. The method described in Patent Document 1 includes a step of chipping and removing a repair portion on the lower surface of the end of the concrete floor slab, and a step of injecting repair mortar into the portion chipped and removed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A clearance is provided between the bridge girder and the parapet provided on the bridge abutment to absorb displacement due to temperature change of the bridge girder. Since a part of rainwater and a part of antifreeze agents sprayed in cold regions are likely to penetrate into the clearance, the end of the bridge girder defining the clearance is likely to be damaged. However, the width of the clearance between the bridge girder and the parapet in the bridge axis direction is narrow, and it is difficult to repair the end of the bridge girder by the method described in Patent Document 1.

[0005] In view of the above background, an object of the present invention is to make it easier to repair the end of a bridge girder in a method for repairing a bridge girder.

Means for Solving the Problems

[0006] A method for repairing an end portion in the bridge axis direction of a bridge girder (3) supported by a pier (2) provided with a parapet (6) on its upper surface, the method comprising: an excavation step (Fig. 2) of excavating a soil work portion (8) disposed on the back side of the pier and the back side of the parapet; a removal step (Fig. 3) of removing an existing expansion device (14) connecting the parapet and the end portion of the bridge girder and at least a part of the parapet after the excavation step; a repair step of repairing the end portion of the bridge girder after the removal step; a construction step (Fig. 8) of constructing a support portion (32) for supporting a newly installed expansion device (33) on the pier and the newly installed expansion device after the repair step; and a backfilling step (Fig. 10) of backfilling the soil work portion on the back side of the pier and the back side of the support portion after the construction step.

[0007] According to this aspect, since the excavation of the soil work portion and the removal of the parapet are performed, a place for performing work for repairing the end portion of the bridge girder can be secured. Therefore, it is possible to facilitate the repair of the end portion of the bridge girder.

[0008] In the above aspect, in the removal step, it is preferable that the entire parapet is removed, and in the construction step, the support portion is constructed on the pier.

[0009] According to this aspect, a place for performing work for repairing the entire end portion of the bridge girder can be secured.

[0010] In the above aspect, in the removal step, only the upper part of the parapet is removed, and in the construction step, the support portion is constructed on the pier via the parapet remaining on the pier.

[0011] According to this aspect, a place for performing work for repairing the upper part of the end portion of the bridge girder can be secured.

[0012] In the above aspect, after the removal step, an expansion step (FIG. 4) of constructing an expansion part (16, 53) for expanding the length in the bridge axis direction of the upper surface of the abutment or the upper surface of the parapet remaining on the abutment toward the geotechnical part side is further included, and the support part may be constructed on the abutment and the expansion part.

[0013] According to this aspect, a place for arranging a new member can be secured below the newly installed expansion device.

[0014] In the above aspect, the support part may have a drain groove (38) provided below the expansion device and extending in a direction intersecting the bridge axis direction.

[0015] According to this aspect, water flowing through the newly installed expansion device and below the expansion device falls into the drain groove. Thereafter, the water is drained from the end of the drain groove in the direction intersecting the bridge axis direction. Therefore, it is difficult for water to accumulate in the support part, and deterioration of the support part is suppressed.

[0016] In the above aspect, the bridge girder has a concrete floor slab (4), and the repair step may include a cutting step (FIG. 5) of cutting off an end portion (4A) of the floor slab supported by the abutment, and a repair part construction step (FIG. 7) of constructing a repair part (21) on the portion of the floor slab cut off after the cutting step.

[0017] According to this aspect, the damaged end portion of the floor slab can be repaired.

[0018] In the above aspect, the bridge girder further has a steel girder (51) extending in the bridge axis direction and on which the floor slab is arranged, and the repair step may further include a steel girder repair step of repairing the end portion of the steel girder in the bridge axis direction.

[0019] According to this aspect, in addition to the damaged end portion of the floor slab, the damaged end portion of the steel girder can be repaired.

[0020] In the above aspect, it is preferable that the repair process further includes a reinforcing process (Fig. 6) of arranging reinforcing bars (18) on the portion of the floor slab cut in the cutting process after the cutting process and before the repair part construction process.

[0021] According to this aspect, deterioration of the repair part is suppressed.

[0022] In the above aspect, the reinforcing bars may be made of a non-ferrous material.

[0023] According to this aspect, deterioration of the end of the repaired floor slab is further suppressed.

[0024] In the above aspect, the support part may be made of precast concrete.

[0025] According to this aspect, the time for constructing the support part on the abutment and the extension part can be shortened. Consequently, the time for repairing the end of the bridge girder can be shortened.

Advantages of the Invention

[0026] The present invention can repair the end of a bridge girder in a method for repairing a bridge girder.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0028] Hereinafter, with reference to the drawings, a method for repairing a bridge girder according to the present invention will be described.

[0029] (First Embodiment) As shown in FIG. 1, the bridge 1 has a pair of abutments 2 (only one is shown in the figure) and a bridge girder 3 supported by the pair of abutments 2. The bridge 1 may include one or more piers (not shown) disposed between the abutments 2. The bridge girder 3 has a concrete floor slab 4 and parapets (not shown) provided along both side edges of the floor slab 4. The floor slab 4 is a hollow floor slab having a hollow structure in the present embodiment. The hollow portion of the floor slab 4 is formed only in the intermediate portion of the floor slab 4 in the bridge axis direction, and the end portion 4A (girder end portion) of the floor slab 4 has a solid structure. In other embodiments, the bridge girder 3 may be a truss bridge having a box girder or a T girder in addition to the floor slab 4. The abutment 2 supports one end portion of the bridge girder 3 in the bridge axis direction via a bearing 5. The other end portion of the bridge girder 3 is supported by another abutment 2 or a pier.

[0030] A parapet 6 extending upward from the upper surface of the abutment 2 is provided on the abutment 2. The parapet 6 is a concrete wall whose length in the bridge axis direction is shorter than the length of the abutment 2 in the bridge axis direction. The parapet 6 extends upward from the upper surface of the back side portion of the abutment 2 on the side opposite to the bridge girder 3. The bearing 5 is disposed on the upper surface of the front side portion of the abutment 2 on the bridge girder 3 side with respect to the parapet 6. The parapet 6 cooperates with the abutment 2 to resist the earth pressure of the earthwork portion 8 disposed on the back side. The earthwork portion 8 is composed of an embankment or crushed stone.

[0031] A clearance 11 for absorbing displacement due to temperature change of the bridge girder 3 is formed between the parapet 6 and the bridge girder 3. In the present embodiment, the clearance 11 is defined by the front surface of the parapet 6 and the end surface of the floor slab 4.

[0032] The parapet 6 is provided with a parapet-side notch 12. Specifically, the parapet-side notch 12 is formed in the upper part on the front side of the parapet 6.

[0033] The floor slab 4 is provided with a floor-slab-side notch 13. Specifically, the floor-slab-side notch 13 is formed in the upper part on the end surface side of the floor slab 4 facing the parapet 6. The bottom surface of the floor-slab-side notch 13 is arranged on the same plane as the bottom surface of the parapet-side notch 12.

[0034] An expansion and contraction device 14 for connecting the parapet 6 and the end of the bridge girder 3 is provided at the upper part of the clearance 11 formed between the parapet 6 and the bridge girder 3. The expansion and contraction device 14 absorbs displacement due to temperature change of the bridge girder 3 while ensuring passage of vehicles, people, etc. The expansion and contraction device 14 may have a so-called finger joint type known configuration including a pair of face plates including a large number of convex portions formed in a comb shape and an embedded portion buried in the parapet 6 or the floor slab 4. Alternatively, the expansion and contraction device 14 may have a known configuration of a rubber type having an expansion and contraction rubber for closing the clearance 11. The expansion and contraction device 14 is arranged on the bottom surfaces of the parapet-side notch 12 and the floor-slab-side notch 13 so as to straddle the clearance 11 formed between the parapet 6 and the bridge girder 3, and is fixed to the parapet 6 and the bridge girder 3.

[0035] A method for repairing the end of the bridge girder 3 configured as described above will be described. The end of the bridge girder 3 before repair refers to the end 4A of the floor slab 4 including the end surface of the floor slab 4 facing the parapet 6.

[0036] As shown in FIG. 2, first, the worker excavates the soil working section 8 (excavation step). The soil working section 8 is excavated by a construction machine such as a backhoe. The soil working section 8 is excavated so that a part of the back surface of the parapet 6 and the back surface of the abutment 2 are exposed. More specifically, the soil working section 8 may be excavated to secure a working place for constructing the abutment extension part 16 provided on the abutment 2 in the extension step described later.

[0037] As shown in FIG. 3, next, the worker removes the existing expansion device 14 and the parapet 6 provided between the parapet 6 and the floor slab 4 (removal step). After removing the existing expansion device 14, the parapet 6 is chopped off by, for example, a water jet or blasting. In this embodiment, the entire parapet 6 is chopped off.

[0038] As shown in FIG. 4, next, the worker constructs an abutment extension part 16 that expands the length of the upper surface of the abutment 2 in the bridge axis direction toward the soil working section 8 (expansion step). The abutment extension part 16 is formed in a block shape and is constructed on the back surface of the abutment 2. The abutment extension part 16 may be formed by placing concrete on site, or may be made of precast concrete. The upper surface of the abutment extension part 16 is arranged on the same plane as the upper surface of the abutment 2. The width of the abutment extension part 16 in the direction perpendicular to the bridge axis is substantially equal to the width of the abutment 2 in the direction perpendicular to the bridge axis. Also, the length of the abutment extension part 16 in the bridge axis direction may be set to such an extent that the support part 32 constructed in the construction step described later can be stably supported.

[0039] Next, the worker repairs the end of the bridge girder 3 (repair step). In the repair step, as shown in FIG. 5, first, the worker chops off the end 4A of the floor slab 4 supported by the abutment 2 (chopping step). The end 4A of the floor slab 4 may be chopped off by the same method as the method of chopping off the parapet 6, or may be chopped off by a different method. The worker may chop off the damaged part of the floor slab 4. In this embodiment, the upper part of the floor slab 4 and the end 4A of the floor slab 4 are chopped off. In other embodiments, the lower part of the floor slab 4 may also be chopped off. If rust is confirmed on the reinforcing bars exposed from the chopped-off part of the floor slab 4, the worker may remove the rust of the reinforcing bars.

[0040] Thereafter, as shown in FIG. 6, the worker arranges reinforcing bars 18 on the portion of the floor slab 4 that has been cut off (reinforcing step). The reinforcing bars 18 are made of non-ferrous materials such as aramid fiber rods or carbon fiber rods. Alternatively, the reinforcing bars 18 may be epoxy-coated steel bars obtained by applying epoxy resin to steel bars. The reinforcing bars 18 are fixed to the floor slab 4 that has not been cut off. Specifically, the ends of the reinforcing bars 18 are inserted into holes (not shown) pre-formed in the floor slab 4 that has not been cut off, and a filler such as mortar is injected into these holes. Due to the solidification of the filler, the reinforcing bars 18 are fixed to the floor slab 4 that has not been cut off. In the present embodiment, a plurality of reinforcing bars 18 are arranged, and a part of the plurality of reinforcing bars 18 is arranged to extend in the bridge axis direction, and the remaining plurality of reinforcing bars 18 are arranged to extend in the vertical direction.

[0041] Thereafter, as shown in FIG. 7, the worker constructs a repair portion 21 on the portion of the floor slab 4 that has been cut off (repair portion construction step). In the present embodiment, after the worker assembles a formwork on the portion of the floor slab 4 that has been cut off, fresh concrete is placed into the formwork. As the fresh concrete hardens, the repair portion 21 is formed. At this time, the plurality of reinforcing bars 18 exposed from the cut-off floor slab 4 are buried in the repair portion 21. The deterioration of the repair portion 21 is suppressed by the reinforcing bars 18. The repair portion 21 may be formed from, for example, Sumitomo Mitsui Construction Co., Ltd.'s Sustaincrete (registered trademark) with reduced carbon dioxide emissions from the material. The upper surface of the repair portion 21 is arranged on the same plane as the upper surface of the floor slab 4, and the lower surface of the repair portion 21 is arranged on the same plane as the lower surface of the floor slab 4.

[0042] The repair section 21 is provided with a repair-section-side mounting portion 23 for mounting the newly installed expansion device 14 in the construction process described later, and a receiving portion 24 for receiving the support portion 32 constructed in the construction process described later. The repair-section-side mounting portion 23 and the receiving portion 24 are provided so as to be recessed from the end surface on the soil engineering portion 8 side of the repair section 21 toward the floor slab 4 side. Specifically, the repair-section-side mounting portion 23 has a bottom surface 26 that is lower than the upper surface of the repair section 21, and a stepped upper surface 27 that connects the upper surface of the repair section 21 and the bottom surface 26 of the repair-section-side mounting portion 23. The receiving portion 24 has a bottom surface 29 that is higher than the lower surface of the repair section 21, and a stepped lower surface 30 that connects the lower surface of the repair section 21 and the bottom surface 29 of the receiving portion 24. In the present embodiment, the length in the bridge axis direction of the bottom surface 29 of the repair-section-side mounting portion 23 is shorter than the length in the bridge axis direction of the bottom surface 29 of the receiving portion 24.

[0043] The end portion of the repair section 21 on the soil engineering portion 8 side forms the end portion of the repaired bridge girder 3. The end portion of the repaired bridge girder 3 is located closer to the soil engineering portion 8 side than the end portion of the bridge girder 3 before repair. At this time, the repair-section-side mounting portion 23 provided on the repair section 21 is located closer to the soil engineering portion 8 side than the floor-slab-side notch portion 13 provided on the floor slab 4 before being cut off.

[0044] As shown in FIG. 8, next, the operator constructs a support portion 32 for supporting the newly installed expansion device 14 and a newly installed expansion device 33 on the abutment 2 (construction process). As shown in FIG. 9, the support portion 32 has a support-portion lower portion 32A disposed on the upper surface of the abutment 2 and the upper surface of the abutment extension portion 16, and a support-portion upper portion 32B disposed above the support-portion lower portion 32A. The support portion 32 is made of precast concrete. The support portion 32 may be formed of, for example, concrete containing fine powder of blast furnace slag.

[0045] The lower part 32A of the support portion has a bottom wall 34 extending in the bridge axis direction and a pair of vertical walls 35 extending upward from both ends of the bottom wall 34 in the bridge axis direction. The width of the bottom wall 34 in the direction perpendicular to the bridge axis and the width of each vertical wall 35 in the direction perpendicular to the bridge axis are substantially equal to the width of the abutment 2 in the direction perpendicular to the bridge axis and the width of the abutment extension portion 16 in the direction perpendicular to the bridge axis. A drainage groove 38 defined by the bottom wall 34 and the pair of vertical walls 35 is formed in the lower part 32A of the support portion. The drainage groove 38 extends in the direction perpendicular to the bridge axis. The upper surface of the bottom wall 34 forming the bottom surface of the drainage groove 38 may be curved in an upwardly convex direction in the direction perpendicular to the bridge axis.

[0046] The upper part 32B of the support portion is formed in a block shape. The upper part 32B of the support portion is provided at the upper end of the vertical wall 35 on the side of the soil engineering portion 8 among the pair of vertical walls 35 of the lower part 32A of the support portion. The upper surface of the upper part 32B of the support portion is arranged on the same plane as the upper surface of the floor slab 4 and the upper surface of the repair portion 21. The width of the upper part 32B of the support portion in the direction perpendicular to the bridge axis is substantially equal to the width of the abutment 2 in the direction perpendicular to the bridge axis and the width of the abutment extension portion 16 in the direction perpendicular to the bridge axis. The length of the upper part 32B of the support portion in the bridge axis direction is longer than the length of the vertical wall 35 in the bridge axis direction where the upper part 32B of the support portion is provided. Specifically, among the ends of the upper part 32B of the support portion in the bridge axis direction, the end on the floor slab 4 side protrudes toward the floor slab 4 side more than the vertical wall 35. Thereby, the end on the floor slab 4 side of the upper part 32B of the support portion closes a part of the upper opening of the drainage groove 38. Also, among the ends of the upper part 32B of the support portion in the bridge axis direction, the end on the soil engineering portion 8 side protrudes toward the soil engineering portion 8 side more than the vertical wall 35.

[0047] A support portion side mounting portion 41 for mounting a newly installed expansion device 33 is provided on the upper part 32B of the support portion. The support portion side mounting portion 41 is provided so as to be recessed from the front surface of the upper part 32B of the support portion facing the end surface of the repair portion 21 toward the soil engineering portion 8 side. Specifically, the support portion side mounting portion 41 has a bottom surface 42 lower than the upper surface of the upper part 32B of the support portion and a stepped upper surface 43 connecting the upper surface of the upper part 32B of the support portion and the bottom surface 42. The bottom surface 42 of the support portion side mounting portion 41 and the bottom surface 26 of the repair portion side mounting portion 23 are arranged on the same plane.

[0048] In the construction process, first, the worker constructs the support part 32 on the abutment 2 and the abutment extension part 16. Specifically, the worker fixes the bottom wall 34 of the lower part 32A of the support part to the abutment 2 and the abutment extension part 16. At this time, among the pair of vertical walls 35 that form the lower part 32A of the support part, the vertical wall 35 on the floor slab 4 side is received by the receiving part 24 provided in the repair part 21. Specifically, the upper end surface of the vertical wall 35 on the floor slab 4 side faces the bottom surface 29 of the receiving part 24. The front surface of the vertical wall 35 on the floor slab 4 side may be arranged at an interval from the stepped lower surface 30 of the receiving part 24. Also, among the pair of vertical walls 35 of the lower part 32A of the support part, the back surface of the vertical wall 35 on the earthwork part 8 side is arranged on the same plane as the back surface of the abutment extension part 16. When the support part 32 is constructed on the abutment 2 and the abutment extension part 16, a clearance 44 defined by the front surface of the upper part 32B of the support part and the end surface of the repair part 21 is formed between the support part 32 and the repair part 21. Since the support part 32 is made of precast concrete, the time for the operation of constructing the support part 32 on the abutment 2 and the abutment extension part 16 can be shortened. Subsequently, the time for the operation of repairing the end part of the bridge girder 3 can be shortened.

[0049] After the support part 32 is constructed on the abutment 2 and the abutment extension part 16, the worker arranges the newly installed expansion device 33. The configuration of the newly installed expansion device 33 may be the same as the configuration of the existing expansion device 14, or may be different from the configuration of the existing expansion device 14. The newly installed expansion device 33 is arranged on the bottom surface 42 of the support part side mounting part 41 and the bottom surface 26 of the repair part side mounting part 23 so as to straddle the clearance 44 formed between the support part 32 and the repair part 21, and is fixed to the upper part 32B of the support part and the repair part 21, that is, the bridge girder 3. At this time, a drain groove 38 is arranged below the newly installed expansion device 33. More specifically, when viewed from the vertical direction, the clearance 44 formed between the support part 32 and the repair part 21 coincides with a part of the opening above the drain groove 38.

[0050] As shown in FIG. 10, next, the worker fills back the earthwork part 8 on the back side of the abutment 2, the back side of the abutment extension part 16, and the back side of the support part 32 (filling-back process). By filling back the earthwork part 8, the abutment 2, the abutment extension part 16, and the support part 32 resist the earth pressure of the earthwork part 8. Thus, the end part of the bridge girder 3 is repaired.

[0051] In the method for repairing the end of the bridge girder 3 described above, since the excavation of the earthwork part 8 and the removal of the entire parapet 6 are performed, a place for performing the work for repairing the entire end of the bridge girder 3 can be secured. Thereafter, by performing the repair process, the end of the bridge girder 3 is repaired. Therefore, it is possible to facilitate the repair of the end of the bridge girder 3.

[0052] Due to the construction of the abutment extension part 16, the support part 32 that resists the earth pressure of the earthwork part 8, that is, the vertical wall 35 on the earthwork part 8 side of the lower part 32A of the support part, is located closer to the earthwork part 8 side than the parapet 6 provided before the repair. As a result, the dimension in the bridge axis direction of the space from the front of the vertical wall 35 on the earthwork part 8 side to the end face on the earthwork part 8 side of the repair part 21 is larger than the dimension in the bridge axis direction of the clearance 11 between the front of the parapet 6 and the end face on the earthwork part 8 side of the floor slab 4. Therefore, a wider space is formed below the newly installed expansion joint 33 compared to before the repair, and a drain 38 can be provided using this space. Since a part of the upper opening of the drain 38 is aligned with the clearance 44 formed between the support part 32 and the repair part 21, water that passes through the newly installed expansion joint 33 due to rainfall or the like and flows below the expansion joint 33 falls into the drain 38. The water that has fallen toward the drain 38 is drained from the openings at both ends in the direction perpendicular to the bridge axis of the drain 38. Therefore, it is difficult for water to accumulate in the support part 32, and the deterioration of the support part 32 is suppressed.

[0053] Referring to FIG. 11, a modified example of the construction process for constructing the support part 32 on the abutment 2 and the abutment extension part 16 will be described. In addition, the same or similar elements as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

[0054] A plurality of reinforcing bars 45 protruding downward from the bottom wall 34 are provided in the lower part 32A of the support part. The plurality of reinforcing bars 45 have a linear shape extending in the vertical direction, and a part of them is arranged at a position where the upper part is embedded in the vertical wall 35 on the side of the soil engineering part 8. The remaining plurality of reinforcing bars 45 are arranged at positions where the upper part is embedded in the vertical wall 35 on the side of the floor slab 4. The plurality of reinforcing bars 45 are arranged at intervals in the direction perpendicular to the bridge axis at positions aligned with each vertical wall 35. A diameter-expanded part 45A (such as a trunk head) is formed at the lower end of each reinforcing bar 45. The diameter-expanded part 45A has a diameter larger than the diameter of other parts of the reinforcing bar 45.

[0055] In the construction process, first, the operator forms holes 46 for receiving the lower parts of the reinforcing bars 45 on the upper surfaces of the bridge abutment 2 and the bridge abutment extension part 16 respectively. The holes 46 formed on the upper surface of the bridge abutment extension part 16 may be formed in advance during the extension process in which the bridge abutment extension part 16 is constructed. Then, the operator fills the holes 46 with a filling material 47 such as non-shrink mortar, and arranges the support part 32 on the bridge abutment 2 and the bridge abutment extension part 16 so that the lower parts of the reinforcing bars 45 provided in the lower part 32A of the support part are inserted into the corresponding holes 46. In the present embodiment, the filling material 47 is also arranged between the bottom wall 34 and the bridge abutment 2 and the bridge abutment extension part 16. Due to the solidification of the filling material 47, the reinforcing bars 45 inserted through the holes 46 and the bottom wall 34 are fixed to the bridge abutment 2 and the bridge abutment extension part 16 via the filling material 47. Thereby, the support part 32 is fixed on the bridge abutment 2 and the bridge abutment extension part 16. The diameter-expanded part 45A can increase the fixing force of the reinforcing bar 45 fixed to the bridge abutment 2 and the bridge abutment extension part 16 via the filling material 47, so that the length of the lower part of the reinforcing bar 45 protruding downward from the bottom wall 34 can be set shorter.

[0056] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 12. Note that the same or similar elements as those in the first embodiment are denoted by the same reference numerals, and the overlapping descriptions are omitted.

[0057] The bridge girder 3 has a steel girder 51 extending in the bridge axis direction and a floor slab 4 disposed on the steel girder 51. The floor slab 4 is made of concrete as in the first embodiment. In this embodiment, the steel girder 51 is formed of H-shaped steel, but it may be formed of other shaped steel materials such as I-shaped steel.

[0058] In the repair process of repairing the end of the bridge girder 3, work for repairing the floor slab 4 and work for repairing the steel girder 51 are performed. Specifically, the repair process includes a chopping process of chopping off the end 4A of the floor slab 4, a construction process of constructing the repair part 21 in the part of the floor slab 4 that has been chopped off, and a steel girder repair process of repairing the end of the steel girder 51 in the bridge axis direction.

[0059] The chopping process may be performed in the same manner as in the first embodiment. At this time, the operator may chop off the end 4A of the floor slab 4 until the upper end of the steel girder 51 is exposed, or may chop off the end 4A of the floor slab 4 so that the upper end of the steel girder 51 is not exposed. The repair part construction process of constructing the repair part 21 in the part of the floor slab 4 that has been chopped off may also be performed in the same manner as in the first embodiment. At this time, instead of the plurality of reinforcing bars 18 extending vertically, for example, stud bolts joined to the steel girder 51 may be newly provided.

[0060] In the steel girder repair process, for example, the operator may shave the surface of the end of the steel girder 51 to remove rust on the end of the steel girder 51. After the surface of the end of the steel girder 51 is shaved, the operator may apply paint to the surface of the end of the steel girder 51 to suppress deterioration of the end of the steel girder 51. Alternatively, the operator may perform cathodic protection by inserting a sacrificial anode for cathodic protection and applying a DC voltage between the sacrificial anode for cathodic protection and the steel girder 51. As described above, the damaged end 4A of the floor slab 4 and the damaged end of the steel girder 51 can be repaired.

[0061] (Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. 13. Note that the same reference numerals are given to the same or similar elements as those in the second embodiment, and redundant descriptions are omitted.

[0062] In the removal process of removing the existing telescopic device 14 and parapet 6, only the upper part of the parapet 6 is cut off. The vertical height of the upper part of the parapet 6 to be cut off is appropriately set according to the range of the end of the bridge girder 3 to be repaired. Next, the operator constructs a parapet extension part 53 that extends the length of the upper surface of the parapet 6 remaining on the abutment 2 in the bridge axis direction toward the geotechnical part 8. The parapet extension part 53 is formed in a block shape similar to the abutment extension part 16 of the second embodiment. The upper surface of the parapet extension part 53 is arranged on the same plane as the upper surface of the parapet 6 remaining on the abutment 2. The parapet extension part 53 may be provided on the back surface of the parapet 6 remaining on the abutment 2, or may be provided on the back surface of the parapet 6 remaining on the abutment 2 and the back surface of the abutment 2. Next, the operator constructs the support part 32 on the parapet extension part 53 and the parapet 6 remaining on the abutment 2. In other words, the support part 32 is constructed on the abutment 2 via the parapet 6 remaining on the abutment 2.

[0063] In the repair process, at least the upper part of the end of the bridge girder 3 is repaired. The operator may only perform the work for repairing the floor slab 4 arranged on the steel girder 51. Alternatively, the operator may perform the work for repairing the floor slab 4 arranged on the steel girder 51 and the work for repairing the upper part of the steel girder 51. Further, the operator may repair the lower part in addition to the upper part of the steel girder 51.

[0064] By removing only the upper part of the parapet 6, a place for performing the work for repairing at least the upper part of the end of the bridge girder 3 can be secured. Since only the upper part of the parapet 6 is removed according to the range of the end of the bridge girder 3 to be repaired, the working time required for the removal process is shortened compared to the case where the entire parapet 6 is removed.

[0065] In other embodiments, the operator may remove the entire parapet 6 in the same manner as in the second embodiment. In this case, in the extension process, before constructing the parapet extension part 53, the operator newly constructs the lower part of the parapet 6 for constructing the parapet extension part 53 on the abutment 2.

[0066] Although the description of the specific embodiments has been completed above, the present invention is not limited to the above embodiments and modifications, and can be widely modified and implemented. For example, in the above embodiment, the repair process is performed after the expansion process, but the expansion process may be performed after the repair process. In the second embodiment, the floor slab 4 is arranged on the steel truss 51, but the floor slab 4 may be arranged on the main girder made of concrete. In this case, the repair of the end of the main girder may be performed in the same manner as the method of repairing the end 4A of the floor slab 4. Further, the specific configuration, arrangement, quantity, material, or process order of each member and part can be appropriately changed as long as it does not deviate from the gist of the present invention. Also, not all of the constituent elements shown in the above embodiments are necessarily essential, and can be appropriately selected.

Explanation of Signs

[0067] 2: Abutment 3: Bridge girder 4: Floor slab 4A: End of the floor slab 6: Parapet 8: Embankment part 14: Existing expansion device 16: Abutment extension part (extension part) 18: Reinforcing bar 21: Repair part 32: Support part 33: Newly installed expansion device 38: Drainage ditch 51: Steel truss 53: Parapet extension part (extension part)

Claims

1. A method for repairing an end portion in the bridge axis direction of a bridge girder supported by a bridge pier provided with a parapet on its upper surface, comprising: an excavation step of excavating a geotechnical part disposed on the back side of the bridge pier and the back side of the parapet; a removal step of removing at least a part of an existing expansion device connecting the parapet and the end portion of the bridge girder and at least a part of the parapet after the excavation step; a repair step of repairing the end portion of the bridge girder after the removal step; a construction step of constructing a support portion for supporting a newly installed expansion device on the bridge pier and the newly installed expansion device after the repair step; a backfilling step of backfilling the geotechnical part on the back side of the bridge pier and the back side of the support portion after the construction step. A method for repairing a bridge girder having these steps.

2. In the removal step, the entire parapet is removed, In the construction step, the support portion is constructed on the bridge pier. The method for repairing a bridge girder according to Claim 1.

3. In the removal step, only the upper part of the parapet is removed, In the construction step, the support portion is constructed on the bridge pier via the parapet remaining on the bridge pier. The method for repairing a bridge girder according to Claim 1.

4. After the removal step, the method further includes an expansion step of constructing an expansion portion that expands the length in the bridge axis direction of the upper surface of the bridge pier or the upper surface of the parapet remaining on the bridge pier toward the geotechnical part side, The support portion is constructed on the bridge pier and the expansion portion. The method for repairing a bridge girder according to Claim 1.

5. The support portion is provided below the expansion device and has a drainage groove extending in a direction intersecting the bridge axis direction. The method for repairing a bridge girder according to Claim 4.

6. The bridge girder has a concrete deck slab, The repair step includes: a chopping step of chopping off the end portion of the deck slab supported by the bridge pier; a repair portion construction step of constructing a repair portion on the portion of the deck slab chopped off after the chopping step. The method for repairing a bridge girder according to Claim 5.

7. The bridge girder further has a steel girder extending in the bridge axis direction and on which the deck slab is disposed, The repair step includes: a steel girder repair step of repairing the end portion in the bridge axis direction of the steel girder. The method for repairing a bridge girder according to Claim 6.

8. The repair step further includes a reinforcement step of arranging reinforcing bars on the portion of the deck slab chopped off after the chopping step and before the repair portion construction step. The method for repairing a bridge girder according to Claim 6 or Claim 7.

9. The reinforcing bars are made of non-ferrous materials, and the method for repairing a bridge girder according to claim 8.

10. The supporting part is made of precast concrete, and the method for repairing a bridge girder according to claim 5.

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