Floor slab replacement method for composite girder bridge

Abstract

To provide a floor slab replacement method capable of replacing a floor slab 5 without reinforcing a main girder 4 in a composite girder bridge 1.SOLUTION: The floor slab replacement method includes a step ST2 of providing a pair of support frames 11 at positions sandwiching the composite girder bridge 1 in the bridge axial direction and bridging a girder 2 between the pair of support frames 11, a step ST3 of cutting the floor slab 5, a step ST4 of moving an intermediate floor slab 31 to the vicinity of the support frames 11 by using the lifting device 25, a step ST5 of removing a girder 3 from the main girder 4, and a step ST6 of placing a plurality of precast floor slabs 45 carried into the vicinity of the support frames 11. A step ST6 disposed at a predetermined position by using a lifting device 25 and a step ST7 for connecting a plurality of precast floor slabs 45 disposed at predetermined positions to each other and connecting them to main girders are included.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a deck replacement method for a composite girder bridge. [Background technology]

[0002] Some viaducts and bridges have a composite girder structure (hereafter referred to as a composite girder bridge) in which a concrete deck is attached integrally to a steel main girder. In composite girder bridges, the deck deteriorates faster than the main girders, so deck replacement work is sometimes carried out to replace the deck.

[0003] When replacing deck slabs, it is known to reinforce the main girders with external cables, bents, reaction frames placed below the main girders, etc., in order to withstand not only the dead load but also the load of work scaffolding and crane trucks in use (see Figures 11 and 1 of Patent Document 1, etc.).

[0004] When removing the deck, a known method is to cut the existing deck perpendicular to the bridge axis (hereinafter referred to as the bridge width direction), and then lift and remove a section of the deck in the bridge axis direction using a crane (Patent Document 2).

[0005] The deck slabs of a composite girder bridge are connected to the main girders by shear stoppers attached to their upper surfaces. Therefore, the deck slab is sometimes cut in the bridge width direction and also in the bridge axis direction to separate the concrete portion between the main girders from the concrete portion above the main girders, and the cut concrete is lifted and removed using a crane or similar device (see, for example, Patent Document 3). In the construction method of Patent Document 3, a deck slab removal device is installed on the deck slab, and the existing deck slab is removed using the deck slab removal device. The deck slab removal device is equipped with first and second portal-shaped lifting devices that lift and lower the existing deck slab, and a transport vehicle that transports the deck slab between the first and second lifting devices. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-8406 [Patent Document 2] Japanese Patent Application Publication No. 2018-123643 [Patent Document 3] Japanese Patent Application Publication No. 2019-173436 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the deck replacement method described in Patent Document 1 requires complicated work to reinforce the main girders. Furthermore, the deck replacement method described in Patent Document 2 requires the main girders to be reinforced so that they can withstand the live load of a crane during operation. To avoid this, it is possible to position a crane outside the span of the composite girder bridge, but this would increase the crane's operating radius, requiring a large crane and increasing construction costs. In some cases, the bridge piers or road structures connected to the composite girder bridge may not be able to withstand the load of a large crane. The deck replacement method described in Patent Document 3 requires a deck removal device to be installed on the composite girder bridge to perform deck removal work, which requires reinforcement of the main girders, making the work complicated.

[0008] In view of the above background, an object of the present invention is to provide a deck replacement method that enables the deck to be replaced without reinforcing the main girders in a composite girder bridge. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, one aspect of the present invention is a deck replacement method for a composite girder bridge (1) having a plurality of main girders (4) extending in the bridge axis direction and a concrete deck (5) constructed integrally on the main girders, the method comprising the steps of: providing a pair of support frames (11) at positions sandwiching the composite girder bridge in the bridge axis direction; bridging a girder (12) between the pair of support frames; providing a lifting device (25) on the girder so as to be movable in the bridge axis direction and the bridge width direction; and replacing an intermediate deck (31) that is a portion of the deck corresponding to a portion between adjacent main girders with the lifting device (25) in the bridge axis direction and the bridge width direction. The method includes a step (ST3) of cutting the deck to separate it from the girder deck (32), which is the part of the deck corresponding to the main girder; a step (ST4) of using the lifting device to move the intermediate deck separated from the girder deck to the vicinity of the support frame; a step (ST5) of removing the girder deck from the main girder; a step (ST6) of using the lifting device to position multiple precast decks (45) brought near the support frame at predetermined positions; and a step (ST7) of connecting the multiple precast decks positioned at the predetermined positions to each other and to the main girder.

[0010] According to this aspect, the intermediate deck can be moved to the vicinity of the support frame using a lifting device that is movable in the axial and transverse directions of the girder, and the precast deck can be placed in the designated position. This allows the deck to be replaced without reinforcing the main girders.

[0011] In the above aspect, the pair of support frames have lateral rails (16) extending in the bridge width direction, and in step (ST2) of erecting the girder, the girder is mounted on the lateral rails of the pair of support frames so as to be movable in the bridge width direction, and a crane (14) is used to transport the intermediate deck from the composite girder bridge near the support frames, or to transport the precast deck from a delivery vehicle onto the composite girder bridge.

[0012] According to this aspect, the distance that the girder can move in the bridge width direction can be increased according to the length of the cross-rail, so that the intermediate deck slab located at the end of the bridge width direction can be easily lifted by the lifting device.

[0013] In the above aspect, at least one of the pair of support frames has two pillars (67) spaced apart in the bridge width direction, and in the step of erecting the girders, the two girders, which are longer than the distance between the support frames, are supported by the corresponding pair of pillars, and in the step of installing the lifting device, vertical movement units (70) are installed on the two girders so that they can move in and out in the bridge axis direction between the pair of support frames, and the lifting device (25) is installed on the vertical movement unit so that it can move in the bridge width direction, and the intermediate deck near the support frame can be transported from the composite girder bridge, or the precast deck can be transported from a delivery vehicle to the composite girder bridge using the lifting device.

[0014] According to this configuration, because the two girders are longer than the distance between the support frames, the lifting device can move not only above the composite girder bridge but also to the outside of the composite girder bridge in the bridge axis direction. This makes it possible to use the lifting device to transport the intermediate deck from the composite girder bridge and to transport the precast deck from a delivery vehicle onto the composite girder bridge. Therefore, there is no need to prepare a crane for these operations, making the work easier.

[0015] In the above aspect, in the step of cutting the deck slab (Figure 9), while cutting the deck slab, support members (35) are attached to the upper surface of the intermediate deck slab so that they extend onto the adjacent pair of girder deck slabs, and the load of the intermediate deck slab is supported by the pair of girder deck slabs via the support members.

[0016] According to this method, there is no need to suspend the deck slab with a lifting device while it is being cut. Therefore, even if the span of the composite girder bridge is long and it takes time to transport the intermediate deck slab with a lifting device, the deck cutting work can be carried out without having to coordinate with the transportation work. This makes it possible to shorten the construction period.

[0017] In the above aspect, the step of removing the girder deck from the main girder (ST5, Figure 11 (E)) may include a step of cutting the lower part of the girder deck approximately horizontally to separate the girder deck from the main girder, and a step of moving the girder deck separated from the main girder to the vicinity of the support frame using the lifting device.

[0018] According to this method, most of the girder deck slab integrated with the main girder can be separated at once by cutting, which allows the girder deck slab to be removed in a shorter time than if the entire girder deck were to be chipped away. [Effects of the Invention]

[0019] According to the above aspect, it is possible to provide a deck replacement method for a composite girder bridge that allows the deck to be replaced without reinforcing the main girder. [Brief explanation of the drawings]

[0020] [Figure 1] Plan view of a composite girder bridge to which the deck replacement method according to the first embodiment is applied [Figure 2] Side view of the composite girder bridge shown in Figure 1 [Figure 3] Cross section III-III in Figure 2 [Figure 4] IV-IV cross section in Figure 2 [Figure 5] VV cross section in Figure 2 [Figure 6] Plan view showing the cutting position of the deck [Figure 7] Flowchart of the deck replacement method according to the first embodiment [Figure 8] Cross-section of a composite girder bridge showing the deck replacement construction method in place [Figure 9] Plan view of the composite girder bridge showing the construction status in Figure 8(B). [Figure 10] Cross-section of a composite girder bridge showing the deck replacement construction method in place [Figure 11] Cross-section of a composite girder bridge showing the deck replacement construction method in place [Figure 12] Side view of a composite girder bridge to which the deck replacement method according to the second embodiment is applied [Figure 13] Cross section XIII-XIII in Figure 12 DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0022] First Embodiment A first embodiment of the present invention will be described with reference to Figures 1 to 11. Figure 1 is a plan view of a composite girder bridge 1 to which a deck slab replacement method according to the first embodiment is applied, and Figure 2 is a side view of the composite girder bridge 1 shown in Figure 1. Figures 1 and 2 show a state during construction of the deck slab replacement method.

[0023] First, we will explain the structure of the composite girder bridge 1. The composite girder bridge 1 is a bridge used as an expressway, spanning between an abutment 2 and a pier 3. The composite girder bridge 1 has five steel main girders 4, shown by dashed lines in Figure 1, extending in the bridge axis direction, and a concrete deck 5 constructed integrally on the main girders 4. The deck slab 5 has a curved planar shape that matches the curves of the expressway. Meanwhile, the main girders 4 are arranged in a straight line, parallel to each other. The composite girder bridge 1 has a gradient in the bridge axis direction as well as a gradient in the bridge width direction.

[0024] Abutment 2 has a box culvert structure that defines the public road within it, allowing for a grade separation between the expressway and a public road. Because the public road extends at an angle to the expressway, abutment 2 has front and rear surfaces that extend at an angle to the bridge axis, and is roughly parallelogram-shaped in plan view. A road has been constructed on the ground on the side of abutment 2 opposite composite girder bridge 1. A reinforced concrete hollow slab bridge 6 is connected to the side of composite girder bridge 1 opposite abutment 2. Therefore, when performing deck replacement work to replace the deteriorated deck 5 of composite girder bridge 1, a large crane cannot be placed on the box culvert abutment 2 or the hollow slab bridge 6 to transport materials in and out.

[0025] Therefore, in this embodiment, when carrying out the deck replacement method, a deck replacement facility 10 shown in Figures 1 and 2 is provided. The deck replacement method and the deck replacement facility 10 used therefor will be described below.

[0026] The deck replacement equipment 10 includes a pair of support cradles 11 provided on the abutment 2 and pier 3, which are support cradles supporting both ends of the composite girder bridge 1, and a girder 12 spanning the pair of support cradles 11. The support cradles 11 do not need to be provided directly on the support cradles; they only need to be located substantially on the support cradles. Specifically, the support cradle 11 on the abutment 2 side is placed on a road constructed on the abutment 2, and the support cradle 11 on the pier 3 side is placed on the hollow deck bridge 6 placed on the pier 3. If the dimension of the abutment 2 in the bridge axis direction is short, the support cradle 11 may be provided on the ground behind the abutment 2. Similarly, if the dimension of the pier 3 in the bridge axis direction is short, the support cradle 11 may be provided on the portion of the hollow deck bridge 6 behind the pier 3.

[0027] In the deck replacement equipment 10 of this embodiment, one girder 12 is spanned between the support frames 11. The girder 12 is arranged horizontally in the bridge axis direction and the bridge width direction. In other words, the height and shape of the pair of support frames 11 are set so that the girder 12 is horizontal. A hand-stretched girder 13 is attached to the end of the girder 12 on the pier 3 side. The girder 12 is assembled using a crane truck 14 arranged on the abutment 2 side, and is spanned between the pair of support frames 11 using a known erection frame (not shown) equipped with a feeding device. In this way, the girder 12 is installed so as to straddle the composite girder bridge 1. It is preferable that the crane truck 14 is placed on the road behind the abutment 2, rather than on top of the abutment 2.

[0028] Figure 3 is a cross-sectional view taken along line III-III in Figure 2, showing the support frame 11 on the pier 3. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 2, showing the support frame 11 on the abutment 2. As shown in Figures 3 and 4, each support frame 11 has a traverse rail 16 extending horizontally in the bridge width direction, and a plurality of support columns 17 that support the traverse rail 16. Each traverse rail 16 is provided with a traverse movement device 18 that can move on the rail in the bridge width direction. The traverse movement device 18 is a self-propelled movement device driven by an electric motor. The girder 12 is supported at both ends by the traverse movement devices 18, and as the traverse movement devices 18 move synchronously in the bridge width direction, the girder 12 moves in the bridge width direction while maintaining an attitude parallel to the bridge axis direction.

[0029] FIG. 5 is a VV cross-sectional view of FIG. 2. As shown in FIG. 5, a vertical movement device 20 capable of moving on the girder 12 in the bridge axis direction is provided on the girder 12. The vertical movement device 20 is a self-propelled movement device driven by an electric motor. A beam 21 extending from the girder 12 to the left and right is integrally provided on the vertical movement device 20. A hoist 22 disposed below the girder 12 is connected to both ends of the beam 21. The hoist 22 includes a cross beam 23, two vertical beams 24 joined to the underside of the cross beam 23, and four lifting devices 25 hanging down from the front and rear ends of each vertical beam 24. The lifting devices 25 in this embodiment are lifting tools such as chain blocks driven by human power. In other embodiments, the lifting devices 25 may be electric lifting devices driven by an electric motor.

[0030] The lifting device 25 lifts the load and the vertical moving device 20 moves, causing the load to move in the bridge axis direction. Also, the lifting device 25 lifts the load and the horizontal moving device 18 moves, causing the load to move in the bridge width direction. In other words, the lifting device 25 installed on the girder 12 can move in the bridge axis direction and the bridge width direction. This lifting device 25 is used to carry out a deck replacement method that includes deck removal work and precast deck placement work.

[0031] The deck replacement equipment 10 is configured as described above. Next, removal of the old deck 5 of the composite girder bridge 1 will be described.

[0032] As described above, the deck slab 5 is constructed integrally with the main girder 4. Therefore, when removing the deck slab 5, the deck slab 5 is divided into multiple pieces by a known method using a device such as a wire saw or a wall saw. When cutting the deck slab 5 using a wire saw, wire-through holes are drilled at appropriate positions using a core boring machine.

[0033] FIG. 6 is a plan view showing the cutting positions of the deck slab 5. As shown in FIG. 6, the deck slab 5 is cut in the bridge axis direction on both sides of each main girder 4 to be separated into an intermediate deck slab 31, a girder deck slab 32, and an overhanging deck slab 33 in the bridge width direction. The intermediate deck slab 31 is the portion of the deck slab 5 corresponding to the space between adjacent main girders 4. The girder deck slab 32 is the portion of the deck slab 5 corresponding to the main girder 4. The overhanging deck slab 33 is the portion of the deck slab 5 overhanging from the main girders 4 at both ends. The deck slab 5 is also cut in the bridge width direction at appropriate positions in the bridge axis direction so as to have an appropriate bridge axis length suitable for removal and transportation. In this embodiment, the overhanging deck slab 33 and the intermediate deck slab 31 are cut to approximately the same bridge axis length, and the overhanging deck slab 32 is cut to a bridge axis length that is approximately half that of the intermediate deck slab 31.

[0034] Next, the procedure for the deck replacement method performed using the deck replacement equipment 10 will be described. FIG. 7 is a flowchart of the deck replacement method according to the first embodiment. As shown in FIG. 7, in order to remove the old deck 5, the cantilever deck 33 is first removed (step ST1). Because the deck 5 is integrated with the main girder 4, the cantilever deck 33 can be removed by placing a crane truck 14 on the composite girder bridge 1. As shown in FIG. 8(A), the cantilever deck 33 can be removed after assembling scaffolding 34 below the main girder 4. The cantilever deck 33 is removed by cutting it along the cutting barge shown in FIG. 6 and transporting it out using the crane truck 14.

[0035] Next, the girder 12 shown in Figures 1 and 2 is assembled (step ST2). Specifically, a pair of support frames 11 are provided on the support platforms (abutments 2, piers 3) that support both ends of the composite girder bridge 1, and the girder 12 is spanned between the pair of support frames 11. After that, a lifting device 25 is provided on the girder 12 so that it can move in the bridge axis direction and the bridge width direction. In this embodiment, since the girder 12 is provided on the lateral rails 16 of the pair of support frames 11 so that it can move in the bridge width direction, it is sufficient that the lifting device 25 is provided on the girder 12 so that it can move in the bridge axis direction.

[0036] Next, the deck 5 is cut as shown in FIG. 6 (step ST3). Specifically, first, both sides of the intermediate deck 31 are cut in the bridge axis direction along the main girders 4 to remove the intermediate deck 31. Once the cutting in the bridge axis direction has progressed to a certain extent, support members 35 for supporting the intermediate deck 31 are attached to the intermediate deck 31, as shown in FIG. 8(B). As also shown in FIG. 9, at least two support members 35 are attached at positions spaced apart in the bridge axis direction. Each support member 35 is attached to the upper surface of the intermediate deck 31 so as to extend over a pair of girder decks 32 adjacent to the intermediate deck 31. As a result, the load of the intermediate deck 31 is supported by the pair of girder decks 32 via the support members 35. Each support member 35 may be provided with a locking portion that is sling-fastened (locked) by the lifting device 25 of the hoist 22.

[0037] Next, the intermediate deck 31, which has been separated from the girder deck 32 by cutting, is removed (step ST4). Specifically, the intermediate deck 31 is lifted using the lifting device 25, and the lifting device 25 is moved in the bridge axial direction to transport the intermediate deck 31 to the vicinity of the support frame 11 on the abutment 2 side. After transportation, the intermediate deck 31 is lowered from the lifting device 25 onto the composite girder bridge 1, and is loaded onto a transport vehicle using a small crane truck 14 (see Figures 1 and 2) placed on or near the abutment 2, and then transported.

[0038] As shown in Figure 10(C), when removing the intermediate deck 31, the lateral movement device 18 (see Figures 1 and 2) is driven to position the intermediate deck 31 directly below the girder 12, and the vertical movement device 20 is driven to position the intermediate deck 31 directly below the hoisting balance 22. In this state, the four lifting devices 25 are engaged with the intermediate deck 31, and the intermediate deck 31 is lifted up. Because support members 35 have been attached in advance to the intermediate deck 31 to be removed, the four lifting devices 25 simply need to be engaged with the locking portions of the support members 35.

[0039] As shown in Figure 10(D), if the intermediate deck 31 is not located directly below the girder 12 even when the girder 12 is moved to the end of the bridge width direction, the intermediate deck 31 is lifted using a special lifting balance 42, which is different from the above-mentioned lifting balance 22. The special lifting balance 42 includes cross beams 23 provided at the front and rear, lifting devices 25 provided on each cross beam 23 so as to be movable in the bridge width direction, and a brace 43 connected to one end of the cross beam 23. The brace 43 is connected to the girder deck 32 or the main girder 4 and supports the cross beam 23 from below. This prevents the lateral movement device 18 and the beam 21 from falling off the girder 12, even if the lifting device 25 is provided at a position offset from the center of the special lifting balance 42 in the width direction.

[0040] After the intermediate deck 31 is lifted using the lifting device 25 of the lifting balance 22 in Figure 10(C) or the special lifting balance 42 in Figure 10(D), the vertical movement device 20 is driven to move the intermediate deck 31 to the vicinity of the support frame 11 on the abutment 2 side. The intermediate deck 31 is removed from the composite girder bridge 1 near the support frame 11 using the crane truck 14 as described above.

[0041] Returning to FIG. 7, next, the girder deck 32 is removed (step ST5). Specifically, a special wall saw or wire saw is attached to the side of the girder deck 32, and the lower part of the girder deck 32 is cut horizontally. After cutting the girder deck 32, as shown in FIG. 11(E), the girder deck 32 is lifted using the lifting device 25 of the hoisting balance 22 or special hoisting balance 42. Then, the vertical movement device 20 is driven to move the lifting device 25 in the bridge axial direction, and the girder deck 32 is transported to the vicinity of the support frame 11 on the abutment 2 side. After transportation, the girder deck 32 is lowered from the lifting device 25 onto the composite girder bridge 1, and is loaded onto a transport vehicle using a small crane truck 14 (see FIGS. 1 and 2) placed on the abutment 2, and then transported. The portion of the girder deck 32 remaining on the main girder 4 is removed by manually chipping it off using a tool such as a breaker or an electric pick.

[0042] Returning to FIG. 7 again, next, the precast deck 45 is erected (step ST6). Specifically, the precast deck 45 is carried in from the delivery vehicle onto the composite girder bridge 1 using a small crane truck 14 (see FIGS. 1 and 2). Next, as shown in FIG. 11(F), the lifting device 25 is engaged with a dedicated lifting jig 46 for lifting the precast deck 45, and the precast deck 45 is lifted. In this state, the vertical transfer device 20 is driven to move the lifting device 25 in the bridge axial direction, and the precast deck 45 is placed in a predetermined position on the main girder 4.

[0043] In this embodiment, as explained with reference to Figure 1, the front face of the box culvert structure abutment 2 extends at an angle to the bridge axis. In other words, the edge of the composite girder bridge 1 is inclined to the bridge axis. For this reason, a new deck 5 is constructed using cast-in-place concrete at the end of the composite girder bridge 1 in the bridge axis direction, and precast deck slabs 45 are used in other parts to shorten the construction period.

[0044] Thereafter, as shown in FIG. 7, the multiple precast slabs 45 are joined together (step ST7). Specifically, the multiple precast slabs 45 arranged in predetermined positions are joined together with filler materials and joined to the main girder 4. Alternatively, the multiple precast slabs 45 may be integrated by inserting tendons through the multiple precast slabs 45 and fixing the tendons in a tensioned state. Adhesives may be used instead of filler materials. Alternatively, the multiple precast slabs 45 may be joined together by pressure bonding using the tension of the tendons, without using filler materials or adhesives.

[0045] Thereafter, the girder 12 is dismantled (step ST8), and the deck slab 5 of the cast-in-place portion is constructed (step ST9), thereby completing the deck slab replacement work.

[0046] Next, the effects of this deck replacement method will be explained.

[0047] The deck replacement method shown in Figure 7 includes step ST2 of providing a pair of support cradles 11 at positions sandwiching the composite girder bridge 1 in the bridge axis direction, spanning a girder 12 between the pair of support cradles 11, and providing a lifting device 25 on the girder 12 so that the lifting device 25 can move in the bridge axis direction and the bridge width direction. The deck replacement method also includes step ST3 of cutting the deck 5 to separate the intermediate deck 31 from the girder deck 32, step ST4 of moving the intermediate deck 31 to the vicinity of the support cradles 11 using the lifting device 25, and step ST5 of removing the girder deck 32 from the main girder 4. The deck replacement method also includes step ST6 of using the lifting device 25 to place multiple precast decks 45 delivered to the vicinity of the support cradles 11 in predetermined positions, and step ST7 of connecting the multiple precast decks 45 to each other and to the main girder 4.

[0048] This makes it possible to use the lifting device 25, which is attached to the girder 12 so as to be movable in the bridge axis direction and the bridge width direction, to move the intermediate deck 31 close to the support frame 11 and place the precast deck 45 in a predetermined position. Therefore, the deck 5 can be replaced without reinforcing the main girder 4.

[0049] As shown in Figures 3 and 4, in this embodiment, a pair of support frames 11 have lateral rails 16 extending in the bridge width direction. In step ST2 of installing the girder 12, the girder 12 is mounted on the lateral rails 16 of the pair of support frames 11 so as to be movable in the bridge width direction. Therefore, the distance that the girder 12 can move in the bridge width direction can be increased depending on the length of the lateral rails 16. Therefore, the intermediate deck slab 31 located at the end in the bridge width direction can be easily lifted by the lifting device 25.

[0050] Furthermore, because the girder 12 is mounted on the cross rail 16 so that it can move in the bridge width direction, the lifting device 25 cannot transport the intermediate deck 31 outward in the bridge axis direction of the composite girder bridge 1. Furthermore, the lifting device 25 cannot lift the precast deck 45 that has been transported outward in the bridge axis direction of the composite girder bridge 1. However, because the intermediate deck 31 near the support frame 11 can be transported out of the composite girder bridge 1 or the precast deck 45 can be transported from a delivery vehicle onto the composite girder bridge 1 using a crane, there is no problem with the work.

[0051] In this embodiment, in step ST3 of cutting the deck slab 5, as shown in Figures 8(B) and 9, support members 35 are attached to the upper surface of the intermediate deck slab 31 so as to extend onto the pair of adjacent girder deck slabs 32 while the deck slab 5 is being cut. As a result, the load of the intermediate deck slab 31 is supported by the pair of girder deck slabs 32 via the support members 35. Therefore, while the deck slab 5 is being cut, there is no need to suspend the deck slab 5 with the lifting device 25. Therefore, even if the span of the composite girder bridge 1 is long and it takes time to transport the intermediate deck slab 31 with the lifting device 25, the cutting work of the deck slab 5 can be carried out without having to coincide with the transportation work. This makes it possible to shorten the construction period.

[0052] In this embodiment, in step ST5 of removing the girder deck 32 from the main girder 4, as shown in FIG. 11(E), the lower part of the girder deck 32 is cut approximately horizontally to separate the girder deck 32 from the main girder 4. Then, the girder deck 32 separated from the main girder 4 is moved to the vicinity of the support frame 11 using a lifting device 25. Therefore, most of the girder deck 32 integrated with the main girder 4 can be separated at once by cutting. Therefore, the girder deck 32 can be removed in a shorter time than when the entire girder deck 32 is chipped off.

[0053] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Figures 12 and 13. Below, differences from the first embodiment will be described, and overlapping descriptions will be omitted.

[0054] FIG. 12 is a side view of a composite girder bridge 1 to which a deck replacement method according to a second embodiment is applied, and FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 12. As shown in FIGS. 12 and 13, in the deck replacement equipment 10 of this embodiment, a pair of support frames 11 each have two columns 67 spaced apart in the bridge width direction, and a girder 12 is provided on each column 67. That is, two girders 12 are bridged between corresponding pairs of columns 67 so as to straddle the composite girder bridge 1 in the bridge axis direction. Both girders 12 have an axial length longer than the distance between the corresponding pairs of columns 67, and protrude from at least one of the support frames 11 in the bridge axis direction. In this embodiment, both girders 12 protrude from both support frames 11 to both sides in the bridge axis direction. Note that each support frame 11 may have three or more columns 67, and at least one girder 12 may be supported by two or more columns 67.

[0055] A vertical movement unit 70 is provided between the two girders 12. Specifically, the vertical movement unit 70 comprises two vertical movement devices 20 provided on both girders 12 so as to be movable in the bridge axis direction, and a horizontal rail 71 provided between both vertical movement devices 20. Both vertical movement devices 20 are electrically driven electric movement devices, and the vertical movement unit 70 moves in the bridge axis direction when both electric movement devices are driven synchronously in the bridge axis direction. A lifting device 25 is provided on the horizontal rail 71 so as to be movable in the bridge width direction.

[0056] With the lifting device 25 hoisting a load, the vertical movement unit 70 moves, causing the load to move in the bridge axis direction. Because the girder 12 protrudes from the support frame 11 in the bridge axis direction, the vertical movement unit 70 can move inside and outside the composite girder bridge 1 in the bridge axis direction. In other words, the vertical movement unit 70 can move a load between the composite girder bridge 1 and the hollow deck bridge 6 or abutment 2. Furthermore, with the lifting device 25 hoisting a load, the lifting device 25 moves on the cross rail 71, causing the load to move in the bridge width direction. In other words, the lifting device 25 provided on the girder 12 can move in the bridge axis direction and the bridge width direction. This lifting device 25 is used to carry out a deck replacement method, including deck removal work and precast deck placement work.

[0057] Specifically, in step ST2 (see FIG. 7) of assembling the girders 12, when the girders 12 are laid out, two girders 12 that are longer than the distance between the support frames 11 are supported by corresponding pairs of support columns 67. Also, in step ST2 of assembling the girders 12, when the lifting devices 25 are installed, vertical movement units 70 are provided on the two girders 12 so that they can move inside and outside the pair of support frames 11 in the bridge axis direction, and the lifting devices 25 are provided on the vertical movement units 70 so that they can move in the bridge width direction.

[0058] In step ST4 of removing the intermediate deck 31, the intermediate deck 31 is carried out from above the composite girder bridge 1 near the support frame 11 by the lifting device 25. In step ST5 of removing the girder deck 32, the girder deck 32 is carried out from above the composite girder bridge 1 near the support frame 11 by the lifting device 25. Furthermore, in step ST6 of erecting the precast deck 45, the precast deck 45 is carried in from a delivery vehicle onto the composite girder bridge 1 by the lifting device 25.

[0059] In this embodiment, since the two girders 12 are longer than the distance between the support frames 11, the lifting device 25 can move not only above the composite girder bridge 1 but also outward in the bridge axis direction of the composite girder bridge 1. This makes it possible to use the lifting device 25 to carry out the intermediate deck 31 from above the composite girder bridge 1 and to carry the precast deck 45 from a delivery vehicle onto the composite girder bridge 1. Therefore, there is no need to prepare a crane for these operations, making the work easier.

[0060] Although the description of specific embodiments has been completed, the present invention is not limited to the above-described embodiments and modifications, and can be implemented in a wide variety of ways. For example, while the composite girder bridge 1 is used as a highway in the above-described embodiment, it may also be used as a general road, railway, sidewalk, etc. in other embodiments. While the girder deck 32 is separated from the main girder 4 by cutting in the above-described embodiment, it may also be separated from the main girder 4 by crushing it using a crushing agent. Furthermore, the steps shown in FIG. 7 may be performed in parallel or in reverse order. Furthermore, the specific configuration, arrangement, quantity, angle, material, procedure, etc. of each component and part may be modified as appropriate without departing from the spirit of the present invention. Meanwhile, not all of the components shown in the above-described embodiment are necessarily required and may be selected as appropriate. [Explanation of symbols]

[0061] 1: Composite girder bridge 4: Main digit 5: Floor slab 11: Support stand 12: Girder 14: Crane truck (crane) 16:Traverse rail 25: Lifting device 31: Intermediate floor slab 32: Girder floor slab 35: Support member 45: Precast deck 67: Strut 70: Vertical moving unit

Claims

[Claim 1] A deck replacement method for a composite girder bridge having a plurality of main girders extending in the bridge axis direction and a concrete deck constructed integrally on the main girders, Providing a pair of support frames at positions sandwiching the composite girder bridge in the bridge axis direction; A step of bridging only one girder between a pair of the support frames; A step of providing a lifting device on the girder so as to be movable in the bridge axis direction and the bridge width direction; A step of cutting the deck slab to separate an intermediate deck slab, which is a portion of the deck slab corresponding to the adjacent main girders, from a girder deck slab, which is a portion of the deck slab corresponding to the main girders; a step of moving the intermediate deck separated from the girder deck to a position near the support frame using the lifting device; removing the girder deck from the main girder; A step of placing the plurality of precast floor slabs carried near the support frame at predetermined positions using the lifting device; and connecting the plurality of precast deck slabs arranged in the predetermined positions to each other and to the main girder, A pair of the support frames has a lateral rail extending in the bridge width direction, In the step of spanning the girder, the girder is provided on the lateral rails of the pair of support frames so as to be movable in the bridge width direction, In the step of providing the lifting device, a suspension balance having a cross beam is provided on the girder, and the lifting device is provided on the cross beam so as to be movable in the bridge width direction; A deck replacement method in which the intermediate deck near the support frame is removed from the composite girder bridge, or the precast deck is transported from a delivery vehicle onto the composite girder bridge using a crane.

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