Floor slab replacement method for bridge

Abstract

To secure a material carry-in / out route even under a condition that an access difficult region continues in a bridge axial direction.SOLUTION: A floor slab replacement method includes a step ST2 and a step ST3 for providing at least one opening 19, 21 in the bridge 1; a crane installation step ST1 and a step ST4 for installing at least one crane on the bridge 1; a step ST6 for separating a part of the existing floor slab 13E from the main girder 11; a carrying-out step ST7 in which an existing floor slab piece 16 is lowered from a girder upper space 23 to a girder lower space 23 through the openings 19 and 21 using a crane and carried out by a carrying-out vehicle 24; a carrying-in step ST9 in which a new floor slab piece 20 is lifted from a carrying-in vehicle 25 using a crane and carried into the girder upper space 18 through the openings 19 and 21; and a step ST10 in which the carried-in new floor slab piece 20 is installed at a predetermined position.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for replacing a floor slab of a bridge, and more particularly to a method for replacing a floor slab that utilizes the under-truss space of a bridge to carry in and out existing floor slab pieces and newly installed floor slab pieces.

Background Art

[0002] In bridges or viaducts such as general roads and expressways, floor slab replacement construction is carried out in which an aging existing floor slab is removed from above the main girder and a new floor slab is reconstructed. For shortening the construction period and the like, the new floor slab is reconstructed by a floor slab replacement construction (see, for example, Patent Document 1) in which precast concrete floor slabs (referred to as precast floor slabs) prefabricated in a factory are arranged in the bridge axis direction.

[0003] The removal of the existing floor slab is performed, for example, by temporarily installing a scaffold below the main girder, cutting the floor slab in the bridge axis direction on both sides of each main girder, and lifting the separated floor slab pieces to a predetermined length in the bridge axis direction by a mobile crane (see FIGS. 45 to 50 of Patent Document 2). The concrete portion remaining on the main girder is crushed using a crusher such as a breaker and removed. The newly installed precast floor slab is transported from the factory to the construction site by a trailer, for example, and lifted by a crane truck installed on the already installed precast floor slab or the existing floor slab, and arranged at a predetermined position on the main girder (see FIG. 51 of Patent Document 2).

[0004] Due to the presence of adjacent roads and neighboring structures in use, when there are restrictions on the turning of the crane on the girder or crane work from the ground, or when the load-bearing capacity of the existing bridge does not support large cranes, there is a problem that large crane trucks cannot be used. Therefore, Patent Document 2 proposes a floor slab replacement method that can perform work efficiently without using a crane truck (see FIGS. 1 to 44 of Patent Document 2). In this method, rails are laid on the main girder from which the existing floor slab has been removed, and a new precast floor slab is installed on the main girder using a gantry-type lifting device and a transport carriage that are provided so as to be movable in the bridge axis direction along the rails.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method proposed in Patent Document 2, in order to transport the precast floor slab for new construction to the transport cart, it is necessary to drive a trailer loaded with the precast floor slab for new construction onto the road where the floor slab replacement is to be carried out. If the width of the road is not wide enough, the trailer has to reverse into the road. Also, if the access point to the bridge or viaduct is far from the construction site and the trailer cannot pass on the road, it takes a lot of time to load the precast floor slab for new construction onto the transport cart.

[0007] Here, it is conceivable to install a crane beside the road where the floor slab replacement is to be carried out and use this crane to transfer the precast floor slab from the trailer outside the bridge or viaduct to the transport cart on the bridge or viaduct. However, in this case, under the condition that areas where it is difficult to access laterally, such as utility lines, rivers, slopes, and residential areas, continue in the bridge axis direction within the construction area, it is impossible to secure an access route for the precast floor slab (the access route for the trailer).

[0008] For example, when the difficult-to-access area is a utility line running parallel to the viaduct where the floor slab replacement is to be carried out, the following are some methods for securing the material access route. First, it is conceivable to provide an alternative road for the utility line and install a hoisting facility beside the viaduct. Second, it is conceivable to install a gantry facility or a construction road that allows materials to be transported in and out across the utility line. Third, it is conceivable to provide an entrance and exit that allows entry from the utility line into the construction area.

[0009] However, in the first and second methods, it is necessary to lease land for installing replacement roads, gantry facilities, and construction roads. Also, the gantry facilities and construction roads are large in size. Therefore, ground improvement may be required to support the load of the facilities. In the third method, it is necessary to manage the entrances and exits so that ordinary vehicles do not accidentally enter the construction area, and traffic guidance such as regulating the speed of the utility line is required when construction vehicles enter and exit.

[0010] In view of the above background, an object of the present invention is to ensure a material loading and unloading route even under the condition that the difficult-to-access area is continuous in the bridge axis direction.

Means for Solving the Problems

[0011] In order to solve the above problems, an aspect of the present invention is a floor slab replacement construction method for replacing an existing floor slab (13E) with a new floor slab (13N) in a bridge (1) having a plurality of main girders (11) extending in the bridge axis direction and a floor slab (13) supported by the main girders. The method includes: removing at least a part in the bridge width direction of the existing floor slab between the main girders adjacent to each other and providing at least one opening (19, 21) in the bridge (steps ST2, ST3); installing at least one crane (17, 22) on the bridge (crane installation steps ST1, ST4); separating a part of the existing floor slab from the main girder (step ST6); using the crane to lift an existing floor slab piece (16) separated from the main girder from the girder upper space (18) above the main girder through the opening to the girder lower space (23) below the main girder and carrying it out by a carrying-out means (24) arranged in the girder lower space (carrying-out step ST7); using the crane to lift a new floor slab piece (20) constituting a part of the new floor slab carried in by a carrying-in means (25) that has entered the girder lower space, and carrying it into the girder upper space through the opening (carrying-in step ST9); and installing the new floor slab piece carried into the girder upper space at a predetermined position (step ST10).

[0012] According to this aspect, it is possible to carry out the removal of the existing floor slab pieces and the loading of the new floor slab pieces by using the under-truss space which is generally the land of the bridge owner (contractor). Therefore, there is no need to borrow the land of a third party for the loading and unloading of these floor slab pieces. Since only the contractor's land is required, the hurdle for using it as a construction site is low, and a construction plan can be established that excludes uncertain factors such as lease agreements with third parties.

[0013] In the above aspect, the bridge (1) further has an inclined bracing structure (12) that connects the main girders (11) adjacent to each other. In the steps (ST2, ST3) of providing the openings (19, 21), a part (12a) of the inclined bracing structure (12) located at a position overlapping the opening in plan view is removed, and the floor slab replacement method preferably further includes a step (ST14) of returning the part of the inclined bracing structure to its original position after the removal step or the loading step.

[0014] According to this aspect, by removing a part of the inclined bracing structure, an opening through which a new floor slab piece can be loaded can be provided in the bridge even if the length (dimension in the bridge width direction) of the new floor slab piece is large. After the floor slab replacement, it can be restored by returning the removed part of the inclined bracing structure to its original position.

[0015] In the above aspect, in the steps (ST2, ST3) of providing the openings (19, 21), an unloading opening (19) for suspending the existing floor slab piece (16) and a loading opening (21) for lifting the new floor slab piece (20) may be provided at positions spaced apart in the bridge axis direction.

[0016] According to this aspect, the unloading means for the existing floor slab pieces and the loading means for the new floor slab pieces can be made to standby at separate positions. Therefore, the work is not interrupted for the replacement of the loading and unloading means, and the construction period can be shortened.

[0017] In the above aspect, in the crane installation steps (ST1, ST4), it is preferable to install a loading crane (17) for loading the existing floor slab piece (16) from the loading opening (19) and a loading crane (22) for loading the new floor slab piece (20) from the loading opening (21).

[0018] According to this aspect, it is not necessary to move the crane every time the loading operation at the loading opening and the loading operation at the loading opening located at a position separated in the bridge axis direction are performed. Therefore, the process is not delayed due to the crane movement.

[0019] In the above aspect, the unloading step (ST7) of unloading the existing floor slab piece (16) using the unloading crane (17) and the loading step (ST9) of loading the new floor slab piece (20) using the loading crane (22) are preferably performed in parallel.

[0020] According to this aspect, the construction period can be shortened by the parallel operation of the unloading step and the loading step.

[0021] In the above aspect, the bridge (1) preferably has at least four main girders (11), and the openings (19, 21) are provided at positions where at least two main girders exist on each of both sides in the bridge width direction of the opening.

[0022] According to this aspect, since there are at least two main girders on each of both sides of the opening, a decrease in the strength of the bridge due to the provision of the opening is suppressed. In particular, torsional deformation of the main girder is suppressed.

[0023] In the above aspect, in the steps (ST2, ST3) of providing the openings (19, 21), it is preferable to leave the portions of the existing floor slab (13E) other than the openings corresponding to the openings in the bridge axis direction.

[0024] According to this aspect, the portions of the existing floor slab other than the openings can be used as a working floor.

[0025] In the above aspect, in the steps (ST2, ST3) of providing the openings (19, 21), it is preferable to remove the entire cross-section in the bridge width direction of the existing floor slab (13E) corresponding to the openings in the bridge axis direction.

[0026] According to this aspect, when forming the openings, the portions of the existing floor slab other than the openings can be removed together, so that the removal work of the existing floor slab can be advanced in one direction and carried out efficiently.

[0027] In the above aspect, in the step (ST6) of separating a part of the existing floor slab (13E) from the main girder (11), it is preferable to separate a part in the bridge width direction of the existing floor slab from the other part in the bridge width direction and maintain the traffic of the other part in the bridge width direction of the existing floor slab.

[0028] According to this aspect, the floor slab can be replaced from the existing floor slab to the newly installed floor slab without completely closing the bridge to traffic.

Advantages of the Invention

[0029] According to the above aspects, even under the condition that the difficult access areas are continuous in the bridge axis direction, a material loading and unloading path can be secured.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying out the Invention

[0031] Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings.

[0032] ≪First Embodiment≫ First, referring to FIGS. 1 to 7, the first embodiment of the present invention will be described. FIG. 1 is a plan view of the periphery of a bridge 1 (1A, 1B) to which the floor slab replacement method according to the first embodiment is applied, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. As shown in FIGS. 1 and 2, in this embodiment, a first bridge 1A used as an upbound two-lane motor vehicle road 2 and a second bridge 1B used as a downbound two-lane motor vehicle road 2 are constructed adjacent to each other. On the side of the first bridge 1A opposite to the second bridge 1B, an ordinary road 5 having a one-lane carriageway 3 and a sidewalk 4 for each of the upper and lower sides is provided. The downbound lane of the ordinary road 5 on the first bridge 1A side is close to the first bridge 1A so that a part of it is located below the first bridge 1A.

[0033] The first bridge 1A and the second bridge 1B have substantially the same configuration. Therefore, hereinafter, the first bridge 1A will be described as a representative of both bridges 1. The first bridge 1A is composed of a plurality of bridge piers 6 (substructures) installed at intervals in the bridge axis direction and a bridge section 7 (superstructure) spanned across these bridge piers 6. The bridge piers 6 in this embodiment are concrete bridge piers. In other embodiments, the bridge piers 6 may be steel bridge piers.

[0034] The bridge section 7 is a girder bridge having a plurality of main girders 11 extending in the bridge axis direction and a diagonal bracing structure 12 connecting these main girders 11, and a floor slab 13 constructed on the girder section 10. The girder section 10 is a steel girder in which the main girders 11 are made of I-shaped steel, and the floor slab 13 is a concrete floor slab made of reinforced concrete. The girder section 10 of the present embodiment includes four main girders 11 and three rows of diagonal bracing structures 12 connecting each pair of adjacent main girders 11. Each main girder 11 is supported by a pier 6 via a bearing 14. In each row between the main girders 11, the diagonal bracing structure 12 is composed of a plurality of diagonal bracing members 12a installed at a predetermined interval smaller than the interval between the piers 6 in the bridge axis direction. High fences 15 are provided at both ends of the floor slab 13 in the bridge axis direction so as to extend in the bridge axis direction.

[0035] In the present embodiment, the floor slab replacement work for replacing the existing floor slab 13E with the new floor slab 13N is sequentially performed for the first bridge 1A and the second bridge 1B. The floor slab replacement work for the first bridge 1A and the floor slab replacement work for the second bridge 1B are performed by the same procedure. Therefore, the floor slab replacement method for the first bridge 1A will be described below as a representative of both bridges 1.

[0036] FIG. 3 is a flowchart showing the procedure of the floor slab replacement method for the first bridge 1A. First, the outline of the procedure of the floor slab replacement method will be described with reference to FIG. 3, and then the details of each procedure will be described with reference to FIGS. 4 to 7.

[0037] When replacing the floor slab 13 of the first bridge 1A, the operator assembles a carry-out crane 17 (FIG. 6) for carrying out an existing floor slab piece 16, which is a part of the existing floor slab 13E separated from the main girder 11, on the first bridge 1A (step ST1). Further, the operator provides a carry-out opening 19 for carrying out the existing floor slab piece 16 from the girder space 18 above the main girder 11 to the outside on the first bridge 1A (step ST2). Similarly, the operator provides a carry-in opening 21 for carrying in a new floor slab piece 20 that constitutes a part of the new floor slab 13N from the outside to the girder space 18 on the first bridge 1A (step ST3). Further, the operator assembles a carry-in crane 22 for carrying in the new floor slab piece 20 into the girder space 18 on the first bridge 1A (step ST4).

[0038] These steps ST1 to ST4 may be performed in any order or may be performed in parallel. Hereinafter, the unloading opening 19 and the loading opening 21 may be simply referred to as openings 19 and 21. Also, the assembly of the unloading crane 17 (step ST1) and the assembly of the loading crane 22 (step ST4) may be simply referred to as the crane installation step. The unloading crane 17 and the loading crane 22 may be cranes (lifting devices) having a gantry structure provided so as to straddle the corresponding openings 19 and 21 when viewed in the bridge axis direction. In this specification, the crane means a lifting device capable of lifting and lowering a load, and the load may or may not be movable in the horizontal direction.

[0039] After the assembly of the unloading crane 17 (step ST1) and the installation of the unloading opening 19 (step ST2), the operator performs the removal work of the existing floor slab 13E. Specifically, the operator (driver) deploys an unloading vehicle 24 for loading the existing floor slab pieces 16 in the under-truss space 23 below the unloading opening 19 (step ST5). Further, the operator sequentially removes a part of the existing floor slab 13E (step ST6), and transports the removed existing floor slab pieces 16 from the unloading opening 19 to the under-truss space 23 using the unloading crane 17 and loads them onto the unloading vehicle 24 (step ST7). The removal of the existing floor slab pieces 16 may be performed from the loading opening 21 toward the unloading opening 19.

[0040] After the removal work of the existing floor slab 13E has progressed to a certain extent, the operator performs the installation work of the new floor slab 13N. Specifically, the operator (driver) deploys a loading vehicle 25 loaded with new floor slab pieces 20 in the under-truss space 23 below the loading opening 21 (step ST8). Subsequently, the operator sequentially transports the new floor slab pieces 20 carried in by the loading vehicle 25 from the loading opening 21 to the above-truss space 18 using the loading crane 22 (step ST9), and sequentially installs the transported new floor slab pieces 20 at the predetermined positions where the existing floor slab 13E has been removed (step ST10).

[0041] When the removal work of the existing floor slab 13E and the installation work of the new floor slab 13N are substantially completed, the operator performs the floor slab replacement work around the opening. Specifically, the operator removes a part of the existing floor slab 13E beside the openings 19 and 21 (step ST11), and carries out the removed part of the existing floor slab 13E from the carry-out opening 19 (step ST12). A part of the removed existing floor slab 13E may be carried out from the carry-in opening 21. Then, the operator carries in the new floor slab piece 20 for the opening position from the carry-in opening 21 (step ST13). The new floor slab piece 20 for the opening position may be carried in from the carry-out opening 19. Then, the operator restores the tilting structural member 12a removed at the openings 19 and 21 (step ST14). Also, the operator installs the carried-in new floor slab piece 20 at the opening position (step ST15). The tilting structural member 12a may be restored to its original position after the new floor slab piece 20 is installed at the opening position. Then, the operator removes the carry-out crane 17 and the carry-in crane 22 (step ST16). Thereby, the floor slab replacement work of the first bridge 1A is completed.

[0042] After the completion of the floor slab replacement work of the first bridge 1A, the floor slab replacement work of the second bridge 1B is carried out. The floor slab replacement work of the first bridge 1A may be carried out after the floor slab replacement work of the second bridge 1B is carried out.

[0043] In this way, by providing the openings 19 and 21 in the bridge 1 and using the gantry cranes (17, 22), it is possible to perform the carry-out step (ST7) of the existing floor slab piece 16 and the carry-in step (ST9) of the new floor slab piece 20 by utilizing the under-truss space 23. Since the under-truss space 23 is generally the land of the owner (operator) of the bridge 1, it is not necessary to borrow the land of a third party for the loading and unloading of these existing floor slab pieces 16 and new floor slab pieces 20. And since only the operator's land is required, the hurdle for using it as a construction site is low, and a construction plan can be established that excludes uncertain factors such as lease agreements with third parties.

[0044] Next, the details of each procedure will be described. FIG. 4 is a plan view around the bridge 1 during the construction of the floor slab replacement method. As shown in FIG. 4, in this embodiment, a loading opening 21 is formed near the center in the bridge axis direction of the construction section, and two unloading openings 19 are formed near both ends of the construction section. By setting the opening positions in this way, construction can proceed from the loading opening 21 toward one direction in the bridge axis direction and from the loading opening 21 toward the other direction in the bridge axis direction. The work proceeding in one direction in the bridge axis direction and the work proceeding in the other direction in the bridge axis direction may be performed in parallel, or one may be performed after the other. Hereinafter, it may be referred to as the front or the forward based on the direction in which the construction proceeds.

[0045] Also, by providing the unloading opening 19 and the loading opening 21 at positions spaced apart in the bridge axis direction, the unloading vehicle 24 for the existing floor slab piece 16 and the loading vehicle 25 for the new floor slab piece 20 can be made to wait at separate positions. Therefore, the work is not interrupted for the replacement of the unloading vehicle 24 and the loading vehicle 25, and the construction period can be shortened.

[0046] FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4. As shown in FIGS. 4 and 5, the unloading opening 19 and the loading opening 21 are formed by removing a part of the existing floor slab 13E in the bridge width direction. Also, the unloading opening 19 and the loading opening 21 are formed to have a predetermined length in the bridge axis direction, and the counter-inclined structural member 12a exists at a position overlapping the openings 19, 21 in plan view. Therefore, when forming the unloading opening 19 and the loading opening 21, the operator removes the counter-inclined structural member 12a. The counter-inclined structural member 12a can be removed from the main girder 11 by loosening bolts (not shown).

[0047] When providing the openings 19, 21 in this way (steps ST2, ST3), the operator removes the counter-inclined structural member 12a at a position overlapping the openings 19, 21 in plan view. As a result, even if the length (dimension in the bridge width direction) of the new floor slab piece 20 is large, the openings 19, 21 through which the new floor slab piece 20 can be loaded can be provided in the bridge 1.

[0048] The unloading opening 19 and the loading opening 21 are formed between the two central main girders 11 out of the four main girders 11. That is, the unloading opening 19 and the loading opening 21 are provided at positions where there are two main girders 11 on each of the two sides in the bridge width direction. Since there are at least two main girders 11 on each side of the openings 19 and 21, the reduction in the strength of the bridge 1 due to the provision of the openings 19 and 21 is suppressed. In particular, the torsional deformation of the main girder 11 is suppressed.

[0049] FIG. 6 is a sectional view taken along line VI-VI in FIG. 5 showing part VI in FIG. 4, and FIG. 7 is a sectional view taken along line VI-VI in FIG. 5 showing part VII in FIG. 4. Note that, although two unloading cranes 17 are shown in FIG. 6, actually only one unloading crane 17 is provided in this area, and two states of the unloading crane 17 working at different positions are illustrated. Similarly, although two loading cranes 22 are shown in FIG. 7, actually only one loading crane 22 is provided in this area, and two states of the loading crane 22 working at different positions are illustrated.

[0050] As shown in FIGS. 5 to 7, one unloading crane 17 is provided for one unloading opening 19. That is, two unloading cranes 17 are provided for two unloading openings 19. Also, one loading crane 22 is provided for one loading opening 21. Alternatively, two loading cranes 22 may be provided on both sides in the bridge axis direction for one loading opening 21. The unloading crane 17 and the loading crane 22 have a similar configuration. Hereinafter, the loading crane 22 will be described as a representative thereof.

[0051] As shown in FIGS. 5 and 7, the loading crane 22 is provided on the bridge 1. Specifically, a pair of guide rails 26 is provided so as to extend in the bridge axis direction above the two main girders 11 adjacent to the loading opening 21. The loading crane 22 is movably provided on the guide rails 26. The guide rails 26 are provided on the floor slab 13 (newly installed floor slab 13N).

[0052] The crane 22 for loading has a pair of running parts 27 that are long in the bridge axis direction and run on the guide rail 26. At different positions in the bridge axis direction of the running parts 27, there are provided front and rear gantry structure parts 28 that connect the two running parts 27. The front and rear gantry structure parts 28 hold a rail 29 extending in the bridge axis direction at the upper part, and a hoist 30 is movably provided on the rail 29. The rail 29 extends forward and backward from the front and rear gantry structure parts 28, and the hoist 30 can move forward and backward beyond the two gantry structure parts 28. The crane 22 for loading can move the newly installed floor slab piece 20 lifted by the hoist 30 in the bridge axis direction by the movement of the hoist 30 and also by the running of the running parts 27.

[0053] Next, with reference to FIG. 6, the removal work of the existing floor slab 13E (steps ST5 to ST7) will be described. Before starting the removal work, the operator secures an access path (construction road) so that the unloading vehicle 24 can enter the under-truss space 23 below the unloading opening 19. The access path may extend from the general road 5 on the side. When removing a part of the existing floor slab 13E, the operator may cut the existing floor slab 13E in the bridge width direction and separate it from the main girder 11 using a known construction method. The operator attaches a lifting jig for locking the lifting tool of the hoist 30 to the existing floor slab piece 16 separated from the main girder 11.

[0054] As shown by arrow A1 in Fig. 6, the operator operates the hoist 30 of the unloading crane 17 to lift the existing floor slab piece 16 separated from the main girder 11. Next, the operator operates the hoist 30 and the traveling unit 27 of the unloading crane 17, and as shown by arrow A2, moves the existing floor slab piece 16 from the rear end to the front end of the loading crane 22, and positions the existing floor slab piece 16 above the unloading opening 19. Then, the operator operates the hoist 30, and as shown by arrow A3, lowers the existing floor slab piece 16, moves it through the unloading opening 19 into the under-girder space 23, and loads it onto the unloading vehicle 24 parked in the under-girder space 23. Then, the operator operates the hoist 30 and the traveling unit 27, and as shown by arrow A4, moves the hoist 30 from the front end to the rear end of the unloading crane 17, and then positions it above the existing floor slab piece 16 to be removed. The operator repeats the above procedures to sequentially remove a part of the existing floor slab 13E forward, that is, from the loading opening 21 toward the unloading opening 19.

[0055] Next, with reference to Fig. 7, the installation work of the new floor slab 13N (steps ST8 to ST10) will be described. Before starting the installation work, the operator secures an access path so that the loading vehicle 25 can enter the under-girder space 23 below the loading opening 21. The access path may extend from the general road 5 located horizontally. The new floor slab piece 20 constitutes a part of the new floor slab 13N, and in this embodiment, it is composed of a precast concrete member having the front width of the new floor slab 13N. It is preferable that a sling jig attachment portion for locking the sling of the hoist 30 is buried in the new floor slab piece 20 in advance.

[0056] As shown by arrow A5 in Fig. 7, the operator operates the hoist 30 of the loading crane 22, lifts the newly installed floor slab piece 20 carried into the under-truss space 23 by the loading vehicle 25, and carries it into the above-truss space 18 through the loading opening 21. Next, the operator operates the hoist 30 and the traveling unit 27 of the loading crane 22, and as shown by arrow A6, moves the newly installed floor slab piece 20 from the rear end to the front end of the loading crane 22, and positions it above the place where the newly installed floor slab piece 20 should be installed (in front of the already installed newly installed floor slab piece 20). Then, the operator operates the hoist 30 and as shown by arrow A7, lowers the newly installed floor slab piece 20 to the place where it should be installed. Then, the operator operates the hoist 30 and the traveling unit 27, and as shown by arrow A8, moves the hoist 30 from the front end to the rear end of the loading crane 22, and positions it above the loading opening 21. The operator repeats the above procedures to sequentially install a part of the newly installed floor slab 13N forward, that is, from the loading opening 21 toward the unloading opening 19.

[0057] After that, the operator performs the floor slab replacement work (steps ST11 to ST13, ST15) around the above openings.

[0058] Also, the operator returns the counter-tilting structural member 12a removed at the openings 19 and 21 (step ST14). The counter-tilting structural member 12a can be fastened to the main truss 11 with bolts loosened during removal. In this way, after the operator removes the counter-tilting structural member 12a at the position of the unloading opening 19 after unloading the existing floor slab piece 16 (step ST7), the operator returns it to its original position, and after loading the newly installed floor slab piece 20 (step ST9), the operator returns the counter-tilting structural member 12a removed at the position of the loading opening 21 to its original position. Thereby, the truss part 10 is restored.

[0059] Thus, in this embodiment, in the crane installation steps (ST1, ST4), an unloading crane 17 for unloading the existing floor slab piece 16 from the unloading opening 19 and a loading crane 22 for loading the new floor slab piece 20 from the loading opening 21 are installed. Thereby, each time the unloading operation at the unloading opening 19 and the loading operation at the loading opening 21, which are at positions spaced apart in the bridge axis direction, are performed, it is not necessary to move the unloading crane 17 or the loading crane 22. Therefore, the process is not delayed due to crane movement.

[0060] In this embodiment, the unloading of the existing floor slab piece 16 using the unloading crane 17 (step ST7) and the loading of the new floor slab piece 20 using the loading crane 22 (step ST9) are performed in parallel. Thereby, the construction period is shortened.

[0061] As described with reference to FIG. 4, when providing the openings 19, 21 (steps ST2, ST3), the operator leaves the portions of the existing floor slab 13E other than the openings 19, 21 corresponding to the openings 19, 21 in the bridge axis direction. Therefore, the portions of the existing floor slab 13E other than the openings 19, 21 can be used as a working floor.

[0062] ≪Second Embodiment≫ Next, with reference to FIG. 8, a second embodiment of the present invention will be described. The same or similar members as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

[0063] FIG. 8 is a cross-sectional view of the bridge 1 during the construction of the floor slab replacement method according to the second embodiment. As shown in FIG. 8, when providing the openings 19, 21 (steps ST2, ST3), the operator removes the entire cross-section in the bridge width direction of the existing floor slab 13E corresponding to the openings 19, 21 in the bridge axis direction. That is, when providing the openings 19, 21 (steps ST2, ST3), the entire cross-section in the bridge width direction of the existing floor slab 13E corresponding to the openings 19, 21 in the bridge axis direction is removed.

[0064] As a result, when forming the openings 19 and 21 (steps ST2 and ST3), the portions of the existing floor slab 13E other than the openings 19 and 21 can be removed together. That is, it is not necessary to perform the operations of steps ST11 to ST13 in FIG. 3 performed in the first embodiment. Therefore, the removal work of the existing floor slab 13E can be advanced in one direction and performed efficiently. Note that, similar to the first embodiment, the unloading crane 17 may be installed on the existing floor slab 13E, and the loading crane 22 may be installed on the newly installed floor slab 13N that has already been installed.

[0065] <<Third Embodiment>> Next, referring to FIG. 9, a third embodiment of the present invention will be described. The same or similar members as those in the first or second embodiment are denoted by the same reference numerals, and redundant descriptions are omitted. In this embodiment, when replacing the floor slab 13 in the first bridge 1A or the second bridge 1B, it is different from the above embodiments in that it is performed one lane at a time and the lanes that are not replaced are not blocked. Hereinafter, the second bridge 1B will be specifically described as an example.

[0066] FIG. 9 shows a state where the replacement work for the right side portion of the floor slab 13 has been completed and the replacement work for the left side portion of the floor slab 13 is being performed. At this time, the operator provides an unloading opening 19 and a loading opening 21 between the two left main girders 11 out of the four main girders 11 and performs the work. The right lane replaced with the newly installed floor slab 13N is in use, and only the left lane is blocked, and the replacement work for the left side portion of the existing floor slab 13E is performed.

[0067] Thus, in this embodiment, when separating a part of the existing floor slab 13E from the main girder 11 (step ST6), the operator separates a part of the existing floor slab 13E in the bridge width direction from the other part in the bridge width direction. And the traffic of the other part in the bridge width direction of the existing floor slab 13E is maintained. Thereby, the floor slab 13 can be replaced from the existing floor slab 13E to the newly installed floor slab 13N without completely blocking the entire bridge 1.

[0068] With the above description of the specific embodiments completed, the present invention is not limited to the above embodiments and variations, and can be widely implemented with various modifications. For example, the shape, number, etc. of the main girders 11 in the bridge 1 are not limited thereto. For example, when the girder part 10 is composed of three main girders 11, the positions of the materials lifted at the openings 19 and 21 will deviate from the center of gravity of the floor slab 13. However, the present invention can be applied by devising facilities to achieve balance. On the other hand, when the girder part 10 is composed of five main girders 11, the distance between the main girders becomes narrower, and the width of the materials that can be carried in and out becomes narrower. However, the present invention can be applied by taking measures such as providing facilities that can lift obliquely.

[0069] Also, the configuration, number, etc. of the cranes are not limited thereto. For example, two outloading cranes 17 may be provided corresponding to the two outloading openings 19, and one inloading crane 22 may be provided corresponding to the one inloading opening 21. In this case, until the construction of two construction sections with different construction directions is completed, the inloading and installation work of the newly installed floor slab piece 20 may be carried out by one inloading crane 22, or the second inloading crane 22 may be assembled when the construction has progressed to a certain extent.

[0070] Also, in the above embodiment, the outloading crane 17 directly loads the existing floor slab piece 16 onto the outloading vehicle 24 through the outloading opening 19. Also, the inloading crane 22 directly lifts the newly installed floor slab piece 20 from the inloading vehicle 25, and carries it into the space above the girder 18 through the inloading opening 21. In other embodiments, another crane may be provided in the space below the girder 23 under at least one of the outloading opening 19 and the inloading opening 21, and at least one of the loading onto the outloading vehicle 24 and the unloading from the inloading vehicle 25 may be performed by this crane. The crane may be integrally provided on the vehicle.

[0071] In addition, the specific configurations, positions, quantities, materials, and the order of construction directions of each member and part can be appropriately changed as long as they do not deviate from the gist of the present invention. Also, the above-described embodiments may be implemented by combining some or all of the configurations with each other. On the other hand, not all of the components shown in the above embodiments are necessarily essential, and they can be appropriately selected.

Explanation of Reference Numerals

[0072] 1 : Bridge 1A : First Bridge 1B : Second Bridge 6 : Bridge Pier 7 : Bridge Section 10 : Girder Section 11 : Main Girder 12 : Counter-Inclined Structure 12a : Counter-Inclined Structure Member 13 : Floor Slab 13E : Existing Floor Slab 13N : New Floor Slab 16 : Existing Floor Slab Piece 17 : Removal Crane 18 : Space Above Girder 19 : Removal Opening 20 : New Floor Slab Piece 21 : Loading Opening 22 : Loading Crane 23 : Space Below Girder 24 : Removal Vehicle (Removal Means) 25 : Loading Vehicle (Loading Means)

Claims

1. A floor slab replacement method for replacing an existing floor slab with a new floor slab in a bridge having a plurality of main girders extending in the bridge axis direction and a floor slab supported by the main girders, comprising: removing at least a part of the existing floor slab in the bridge width direction between the adjacent main girders to provide at least one opening in the bridge; a crane installation step of installing at least one crane on the bridge; separating a part of the existing floor slab from the main girder; a carrying-out step of using the crane to lift a piece of the existing floor slab separated from the main girder from the girder upper space above the main girder through the opening to the girder lower space below the main girder, and carrying it out by a carrying-out means provided in the girder lower space; a carrying-in step of using the crane to lift a piece of the new floor slab constituting a part of the new floor slab carried in by a carrying-in means entering the girder lower space, and carrying it into the girder upper space through the opening; and a step of installing the piece of the new floor slab carried into the girder upper space at a predetermined position. A floor slab replacement method for a bridge.

2. The bridge further has an inclined strut connecting the adjacent main girders, in the step of providing the opening, removing a part of the inclined strut located at a position overlapping the opening in plan view, and the floor slab replacement method further includes a step of returning the part of the inclined strut to its original position after the carrying-out step or the carrying-in step. The floor slab replacement method for a bridge according to Claim 1.

3. In the step of providing the opening, a carrying-out opening for lifting the piece of the existing floor slab and a carrying-in opening for lifting the piece of the new floor slab are provided at positions spaced apart in the bridge axis direction. The floor slab replacement method for a bridge according to Claim 1 or 2.

4. In the crane installation step, a carrying-out crane for carrying out the piece of the existing floor slab from the carrying-out opening and a carrying-in crane for carrying in the piece of the new floor slab from the carrying-in opening are installed. The floor slab replacement method for a bridge according to Claim 3.

5. The carrying-out step of carrying out the piece of the existing floor slab using the carrying-out crane and the carrying-in step of carrying in the piece of the new floor slab using the carrying-in crane are performed in parallel. The floor slab replacement method for a bridge according to Claim 4.

6. The bridge floor replacement method for a bridge according to claim 1 or 2, wherein the bridge has at least four main girders, and the opening is provided at a position where at least two main girders exist on each of both sides in the bridge width direction of the opening.

7. In the step of providing the opening, a portion of the existing floor slab other than the opening corresponding to the opening in the bridge axis direction is left as a working floor, and the bridge floor replacement method for a bridge according to claim 1 or 2.

8. In the step of providing the opening, the entire cross-section in the bridge width direction of the existing floor slab corresponding to the opening in the bridge axis direction is removed, and the bridge floor replacement method for a bridge according to claim 1 or 2.

9. In the step of separating a part of the existing floor slab from the main girder, a part of the existing floor slab in the bridge width direction is separated from the other part in the bridge width direction, and the traffic of the other part in the bridge width direction of the existing floor slab is maintained, and the bridge floor replacement method for a bridge according to claim 1 or 2.

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