Floor slab installation height adjusting mechanism and floor slab replacement method

Abstract

To provide a floor slab installation height adjusting mechanism and a floor slab replacement method, for adjusting height in a large recess-projection surface for exposing an aggregate, by being applied to a replacement method for a precast floor slab of a PC synthetic girder.SOLUTION: A floor slab installation height adjusting mechanism 1 that adjusts an installation height when a precast floor slab PC1 is erected is provided with a plurality of height adjusting bolts 2 that are screwed into female screw jigs (height adjusting fittings 21) embedded in the precast floor slab PC1 and are capable of protruding and retracting from a lower surface of the precast floor slab PC1, and a plurality of pedestals 3 provided at positions in contact with lower ends of the plurality of height adjusting bolts 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a slab installation height adjustment mechanism that adjusts the installation height of a newly installed precast slab during slab replacement work for PC composite girders, and a slab replacement method using the same. [Background technology]

[0002] In previous deck renewal work (deck replacement work), the existing deck was cut and removed using cutting equipment such as a water jet (WJ), cutter, or wire saw, and then replaced with a cast-in-place concrete deck. However, when constructing a concrete deck using cast-in-place concrete, the construction period on site is long due to traffic restrictions, so shortening the on-site construction period was an issue.

[0003] In order to solve these problems, the applicant has developed a deck replacement method in which the existing main girder stirrups are cut and an anchoring steel pipe is crimped onto the tip, thereby maintaining the stirrup's functionality, and the stirrups are extended into the cutouts in the PC deck by crimping a steel pipe, thereby maintaining the necessary load-bearing capacity even when the main girder web sways.

[0004] Patent Document 1 discloses a method of replacing a concrete bridge with a precast deck slab, in which the upper part of the main girder that joins to the RC deck slab of the concrete bridge is chipped away to expose the upper part of a tensile resistance material such as a stirrup, the exposed tensile resistance material is cut partway and effectively fixed with mechanical fixing means to reduce the effective composition of the main girder, and then a precast deck slab is placed on top of the main girder with its effective composition reduced (see claim 1 in the scope of claims of Patent Document 1, paragraphs

[0025] to

[0044] of the specification, Figures 3 to 9 of the drawings, etc.).

[0005] Furthermore, Patent Document 2 discloses a method of replacing a concrete bridge with a precast deck, in which the upper part of the main girder that joins to the RC deck of a concrete bridge is chipped away to expose the upper part of a tensile resistance material such as a stirrup, the exposed tensile resistance material is cut partway and effectively fixed with mechanical fixing means, a shear stopper is connected to the mechanical fixing means, a precast deck with a box-cut hole is placed on top of the main girder, the shear stopper is accommodated in the box-cut hole, and a filler material is filled in and hardened, thereby integrating the precast deck and the main girder (see claim 1 of Patent Document 2, paragraphs

[0032] to

[0069] of the specification, Figures 3 to 9 of the drawings, etc.).

[0006] In the methods for replacing concrete bridges with precast decks described in Patent Documents 1 and 2, the deteriorated deck on the main girders is removed using a water jet, and then a new precast deck is erected between the girders to replace the deck. When erecting a precast deck, the deck height is typically adjusted using "height adjustment bolts" to ensure it is installed at a predetermined position and height. However, the concrete at the top of the main girders removed with a water jet leaves an uneven surface with exposed aggregate and rebar. Therefore, if a precast deck is erected on this uneven surface and the deck height is adjusted using height adjustment bolts, it will be affected by the unevenness of the concrete. In other words, rotating the height adjustment bolts during adjustment causes the abutting concrete to collapse, shifting the deck's position, making it difficult to adjust the deck's horizontal position.

[0007] On the other hand, Patent Document 3 discloses that the height of the steel deck 30 can be adjusted by raising and lowering the steel deck 30 by turning the height adjustment bolt 40 in the forward or reverse direction as appropriate, so that the upper surface of the paved portion 34 of the steel deck 30 and the upper surface of the paved portion 15 of the reinforced concrete deck 14 are approximately flush with each other (see paragraph

[0061] of the specification of Patent Document 3, Figure 14 of the drawings, etc.).

[0008] Furthermore, Patent Document 4 discloses that the installation height of the precast concrete slab 10 can be adjusted using a height adjustment bolt 30 equipped with a universal mechanism 33 that can swivel in any direction, and that even if there is warping or unevenness in the precast concrete slab 10 or if there is a slope or unevenness on the upper surface 40a of the slab support member 40 on which the precast concrete slab 10 is installed, the height adjustment of the precast concrete slab 10 can always be performed quickly and accurately in a stable state (see paragraphs

[0035] to

[0038] of the specification of Patent Document 4, and Figures 3 to 5, 9, 12, 13, etc. of the drawings).

[0009] However, the height adjustment bolt 40 described in Patent Document 3 and the height adjustment bolt 30 equipped with the universal mechanism 33 described in Patent Document 4 are not designed to adjust the height on highly uneven surfaces where aggregate chipped off by a water jet is exposed, and are unable to solve the problem described above that on such highly uneven surfaces, the concrete that the height adjustment bolt comes into contact with during adjustment may collapse and become misaligned. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 6845456 [Patent Document 2] Patent No. 6845457 [Patent Document 3] Patent No. 6757834 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-92438 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, the present invention was devised in consideration of the above-mentioned problems, and its purpose is to provide a deck installation height adjustment mechanism and deck replacement method that can be applied to the method of replacing the above-mentioned PC composite girders with precast decks, and that can adjust the height on surfaces with large irregularities where aggregate is exposed. [Means for solving the problem]

[0012] The deck installation height adjustment mechanism of claim 1 is a deck installation height adjustment mechanism that adjusts the installation height when erecting a precast deck, and is characterized by comprising a plurality of height adjustment bolts that are threaded into female threaded jigs embedded in the precast deck and can be freely protruded and retracted from the underside of the precast deck, and a plurality of pedestals positioned in contact with the lower ends of the plurality of height adjustment bolts.

[0013] The deck installation height adjustment mechanism of claim 2 is characterized in that, in the deck installation height adjustment mechanism described in claim 1, the base consists of an iron plate portion made of steel plate or iron plate and a block-shaped block portion for securing a certain space.

[0014] The deck replacement method of claim 3 is a deck replacement method for replacing deteriorated concrete deck portions of a bridge consisting of composite girders with new precast decks, and includes a joint concrete removal process for chipping off and removing the concrete from the composite portions of the composite girder bridge girder using a water jet, and a precast deck erection process for erecting the precast deck on top of the bridge girder from which the concrete was removed in the joint concrete removal process, wherein the precast deck erection process uses the deck installation height adjustment mechanism described in claim 1 or 2 to erect the precast deck so that the height adjustment bolts are positioned on top of the multiple pedestals installed on the bridge girder from which the concrete was removed using a water jet in the joint concrete removal process, and the installation height of the precast deck is adjusted with the height adjustment bolts. [Effects of the Invention]

[0015] According to the inventions of claims 1 to 3, in the replacement or renewal work of a concrete deck slab of a composite girder with a precast deck slab, after the concrete at the composite part between the bridge girder (main girder) and the concrete deck slab is chipped off and removed with a water jet, height adjustment becomes easy on the upper surface of the bridge girder where the aggregate is exposed and has large irregularities. In addition, when rotating the height adjustment bolt during adjustment, the problem of the abutting concrete collapsing or sliding on the uneven surface of the aggregate causing the deck slab to shift in position is solved, and the horizontal position of the deck slab also becomes easy to adjust.

[0016] In particular, according to the invention of claim 2, the base is made up of two parts: a steel plate part and a block part. This allows the steel plate part to counteract the friction that occurs when the height adjustment bolt rotates during height adjustment, while the block part ensures space in the vertical direction, reducing the protruding length of the height adjustment bolt and shortening the time required to screw in and remove the height adjustment bolt. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a partial vertical cross-sectional view of a bridge showing a deck installation height adjustment mechanism according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged vertical cross-sectional view showing an enlarged portion of a height adjusting bolt of the deck slab installation height adjusting mechanism. [Figure 3] FIG. 3(a) is a schematic cross-sectional view showing the vicinity of the base of the deck slab installation height adjustment mechanism, and FIG. 3(b) is a perspective view showing the base alone. [Figure 4] Figure 4 shows an overview of the method of replacing concrete bridges with precast decks in Patent Documents 1 and 2, and a vertical cross-sectional view of the existing bridge showing the removed sections, where (a) shows the section where the concrete will be removed, and (b) shows the cutting positions of the concrete and rebar. [Figure 5] FIG. 5 is a partially enlarged perspective view showing the state in which the stirrup is extended in the method of replacing the concrete bridge with a precast deck slab, in the state in which the precast deck slab has been replaced. [Figure 6] FIG. 6 is a process explanatory diagram showing the temporary facility installation process of the deck slab replacement method according to the embodiment of the present invention. [Figure 7] FIG. 7 is a process explanatory diagram showing the joint concrete removal process of the deck replacement method. [Figure 8] FIG. 8 is a process explanatory diagram showing the overhang deck removal process of the deck replacement method. [Figure 9] FIG. 9 is a process explanatory diagram showing the running plate installation process of the deck replacement method. [Figure 10] FIG. 10 is a process explanatory diagram showing the deck cutting and removal process of the deck replacement method. [Figure 11] FIG. 11 is a process explanatory diagram showing the girder upper part forming process of the deck replacement method. [Figure 12] FIG. 12 is a process explanatory diagram showing the stirrup extension process of the deck replacement method. [Figure 13] FIG. 13 is a process explanatory diagram showing the precast deck erection process of the deck replacement method. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of a deck slab installation height adjustment mechanism and a deck slab replacement method according to the present invention will be described in detail with reference to the drawings.

[0019] [Deck installation height adjustment mechanism] First, a deck slab installation height adjustment mechanism 1 according to an embodiment of the present invention will be described using Figures 1 to 3. Figure 1 is a partial vertical cross-sectional view of a bridge showing the deck slab installation height adjustment mechanism 1 according to an embodiment of the present invention, and Figure 2 is a partial enlarged vertical cross-sectional view showing an enlarged portion of the height adjustment bolt of the deck slab installation height adjustment mechanism 1. Figure 3(a) is a schematic cross-sectional view showing the vicinity of the base 3 of the deck slab installation height adjustment mechanism 1, and Figure 3(b) is a perspective view showing the base 3 alone. The following describes an example of height adjustment when replacing a deteriorated deck portion of an existing T-shaped bridge B1, which has a PC composite T-girder as the main girder G1, with a precast deck PC1 after removing it using a water jet.

[0020] As shown in Figure 1, the deck installation height adjustment mechanism 1 of an embodiment of the present invention comprises a plurality of height adjustment bolts 2,...,2 that are threaded into female threaded jigs embedded in the precast deck PC1 and can be freely protruded and recessed from the underside of the precast deck PC1, and a plurality of pedestals 3,...,3 that are positioned to contact the lower ends of these height adjustment bolts 2,...,2, and has the function of installing the precast deck PC1 at a predetermined height above the main girder G1, which is a bridge girder, in an adjustable height manner.

[0021] (Height adjustment bolt) As shown in Figure 2, the height adjustment bolt 2 in this embodiment consists of an M30 bolt, and a height adjustment fitting 21, which is an M30 female thread jig that screws into this M30 bolt, is pre-embedded in the concrete part of the precast deck PC1.

[0022] In addition, above this height adjustment fitting 21, a guide sheath 22 without a female thread is installed, because if the height adjustment fitting 21, which is the female threaded portion that screws into the height adjustment bolt 2, becomes longer, it will take longer to screw the height adjustment bolt 2 into the precast deck slab PC1.

[0023] The height adjustment bolt is not limited to the illustrated form, and may be of another structure as long as it is configured to be able to freely adjust the length of the protruding portion by screwing into and rotating a female threaded jig embedded in the precast deck PC1.

[0024] (pedestal) As shown in Figures 3(a) and 3(b), the base 3 consists of an upper iron plate portion 30 made of a rectangular steel or iron plate and a block-shaped lower block portion 31 for securing a certain amount of space. The iron plate portion 30 is adhered to the upper part of the block portion 31 with an adhesive. In this embodiment, the block portion 31 is made of a mortar block, which is lighter per unit volume than steel. However, the block portion 31 can be made of any material as long as it can secure a certain amount of space and has a compressive strength equivalent to that of the surrounding concrete. Furthermore, the lower block portion 31 of the base 3 is fixed with a time-hardening material 32, such as mortar or adhesive, to the uneven upper surface of the main girder G1, where the deck slab portion has been removed using a water jet to expose the aggregate and other materials.

[0025] The reason why the base 3 is made up of two parts, an iron plate portion 30 and a block portion 31, is that the iron plate portion 30, which comes into contact with the lower end of the height adjustment bolt 2, is made of a steel or iron plate that is hard and highly wear-resistant, thereby resisting friction when the height adjustment bolt 2 rotates during height adjustment, and the block portion 31, which is made of a mortar block, reduces weight, ensuring space in the vertical direction, and reduces the protruding length of the height adjustment bolt 2, thereby shortening the work time required to screw in and remove the height adjustment bolt 2.

[0026] As shown in Figure 3(b), the iron plate portion 30 is coated with an anti-rust coating to prevent rust. Of course, the iron plate portion 30 may be made of stainless steel, which does not rust, and the anti-rust coating may be omitted. Furthermore, if height is not required, the base 3 may be made only of an iron plate such as steel or cast iron, omitting the block portion 31.

[0027] [Deck replacement method] Next, a deck replacement method according to an embodiment of the present invention will be described with reference to Figures 4 to 13. An example will be described in which the previously described deck installation height adjustment mechanism 1 is used to replace the deteriorated concrete deck portion of an existing T-shaped bridge B1, which has a PC composite T-girder as the main girder G1, with a precast deck PC1. Note that the symbol C1 indicates the cantilever deck C1, the symbol C2 indicates the intermediate deck C2, and the symbol C3 indicates the intermediate deck C3. Furthermore, the symbol Wb indicates the wall parapet Wb.

[0028] First, using Figures 4 and 5, we will explain the outline and removed portion of the method for replacing a concrete bridge with a precast deck slab (hereinafter referred to as the SP clamp method) described in Patent Documents 1 and 2, which are described in the background art to which this invention applies. Figure 4 is a vertical cross-sectional view of the existing bridge showing the outline and removed portion of the SP clamp method, where (a) shows the portion from which the concrete has been removed, and (b) shows the cutting positions of the concrete and rebar. Also, Figure 5 is a partially enlarged perspective view showing the state of the stirrup when extended in the SP clamp method, after it has been replaced with a precast deck slab.

[0029] The SP clamp method developed by the applicant is a deck replacement method for the existing decks (extending deck C1, intermediate deck C2, intermediate deck C3) of Bridge B1, a PC composite girder bridge, by removing the deteriorated cast-in-place concrete deck sections and replacing them with precast deck PC1 while maintaining the load-bearing capacity of the existing structure.

[0030] Specifically, in the SP clamp method, as shown in Figures 4(a) and 4(b), the overhanging deck C1 is cut and removed using a concrete cutter 5 or similar, the stirrup Sr, which is part of the internal reinforcement of the existing main girder G1, is cut along the cutting line L1 shown by the dashed dotted line, and then the function of the stirrup Sr is maintained by crimping a mechanical anchor Mf to its tip as shown in Figure 5. Furthermore, this SP clamp method extends the stirrup Sr by crimping a steel pipe Sp (steel pipe crimping) into the cutout part Np of the precast deck PC1, making it possible to maintain the necessary load-bearing performance even when the web of the main girder G1 swings.

[0031] Here, the symbol As in the figure denotes the shear-stop rebars that were installed later on the top surface of the main girder G1, and the cutting line L2 is the concrete removal line along which the concrete is removed using a water jet. Note that the cutting line L1 can also be cut with a wire saw or similar tool, since it cuts the internal reinforcing bars (rebars) along with the concrete.

[0032] The deck replacement method according to this embodiment is an improved version of the SP clamp method, in which the concrete deck portion is cut and removed from the existing PC composite girder, and then a new precast deck PC1 is erected by adjusting its height using the aforementioned deck installation height adjustment mechanism 1.

[0033] (Advance preparation) In the deck replacement method according to this embodiment, preliminary preparations include first installing a temporary concrete vehicle protection fence Pf in the center of the road surface of bridge B1 to separate the road bridge traffic lane from the traffic-restricted zone for the renewal work (see Figure 6). Then, soundproof walls are removed, the asphalt pavement in the work area is cut, and obstructive guardrails and the like are removed.

[0034] (Temporary facility installation process) Next, in the deck replacement method according to this embodiment, a temporary facility installation process is carried out to install necessary temporary facilities around the bridge B1 where the work is to be carried out, as shown in Fig. 6. Fig. 6 is a process explanatory diagram showing the temporary facility installation process of the deck replacement method according to this embodiment.

[0035] Specifically, in this process, as shown in Figure 6, a support structure Sh1 for the cantilever deck C1 is installed under the cantilever deck C1 using temporary materials such as single pipes and bitie scaffolding to support the cantilever deck C1, which also serves as scaffolding, so that it does not fall, and a support structure Sh2 for the intermediate deck C3 is installed under the intermediate deck C3 using temporary materials such as square pipes and pipe supports to support the intermediate deck C3 so that it does not fall.

[0036] (Extended deck removal process) Next, in the deck replacement method according to this embodiment, an overhanging deck removal process is carried out in which the overhanging deck C1 and the wall parapet Wb are cut and removed, as shown in Fig. 7. Fig. 7 is a process explanatory diagram showing the overhanging deck removal process of the deck replacement method according to this embodiment.

[0037] Specifically, in this process, as shown in Figure 7, the overhanging deck C1 is cut approximately vertically using the aforementioned concrete cutter 5 or the like, and then lifted and transported using a crane or the like to remove the overhanging deck C1 and wall parapet Wb.

[0038] (Concrete joint removal process) Next, in the deck replacement method according to this embodiment, a joint concrete removal process is carried out to remove concrete from the composite section SC, which is the joint between the concrete deck and the top of the main girder G1, which is a PC composite girder, as shown in Figure 8. Figure 8 is a process explanatory diagram showing the joint concrete removal process of the deck replacement method according to this embodiment.

[0039] Specifically, in this process, as shown in Figure 8, the concrete in the composite section SC is removed along the cutting line L2 using a water jet. As mentioned above, the stirrup Sr is stretched by crimping the steel pipe Sp and the mechanical anchor Mf is crimped to maintain the function of the stirrup Sr, so the rebar is left in place and only the concrete part is removed (see also Figure 4(b)). In this process, after the concrete part is removed with a water jet, it is preferable to remove the stirrup Sr and any unnecessary rebar by cutting and removing it.

[0040] (Running board installation process) Next, in the deck replacement method according to this embodiment, a running plate installation step is carried out in which the running plate 4 is erected and installed in the recess R1 created by removing the composite section SC in the joint concrete removal step, as shown in Figure 9. Figure 9 is a process explanatory diagram showing the running plate installation step of the deck replacement method according to this embodiment.

[0041] <Running board> Here, the running plate 4 is a plate material based on a rectangular checker plate (checkered steel plate) 40 with anti-slip striped protrusions formed in a repeated pattern on the surface (upper surface) of the steel plate, and as will be described later, has the function of covering and smoothing the uneven surface where aggregate and rebar are exposed after concrete has been chipped away with a water jet, thereby facilitating the travel of the concrete cutter 5. Of course, the checker plate 40 is not limited to a steel plate, and may be a metal plate such as a stainless steel plate or an aluminum steel plate, or an FRP plate.

[0042] A runaway prevention material 6 is attached to the upper surface of this running plate 4 to hook and stop the running wheels 51 of the concrete cutter 5 from running away from the cutting end on the protruding deck C1 side of the upper surface of the main girder G1.

[0043] In addition, an inclined plate 41 is attached to the upper surface of the running plate 4, so that the running wheels 51 of the concrete cutter 5 ride on it, causing the concrete cutter 5 to run at an angle and cut the concrete floor slab (intermediate floor slab C2) at an angle.

[0044] A pair of left and right anti-slip members 42 are attached to the underside of this checker plate 40 (running plate 4) to prevent the checker plate 40 from shifting horizontally on the top surface of the main girder G1. These anti-slip members 42 are made of L-shaped angle irons (equal leg angle irons) and are joined to the top surface of the checker plate 40 by welding or the like. Of course, the anti-slip members 42 are not limited to steel material, and may be any angle material made of metal or FRP.

[0045] <Concrete cutter> The concrete cutter 5 is a hand-pushed or semi-self-propelled concrete cutter that has a wet or dry diamond blade 50 driven by an electric motor or engine and has a plurality of running wheels 51 for travel.

[0046] <Escape prevention material> The runaway prevention material 6 is made of an L-shaped angle material such as an equal-leg angle iron, and is joined by welding or the like to the upper surface of the checker plate 40. Of course, the runaway prevention material 6 is not limited to steel material, and may be any angle material made of metal or FRP.

[0047] Specifically, in this process, as shown in Figure 9, a running plate 4 made of a rectangular checker plate 40 with anti-slip striped protrusions formed in a repeated pattern on the surface (top surface) of the steel plate is placed across and covers the recessed portion R1. This is to enable the concrete cutter 5 to cut the intermediate deck C2 (concrete deck) by running over the smooth, anti-slip checker plate 40, which is easy to run over, without having to run over the uneven surfaces where aggregate and rebar are exposed on the bottom and sides of the recessed portion R1 where the concrete has been chipped away with the water jet.

[0048] As mentioned above, the checker plate 40 of the running board 4 has an anti-runaway material 6 and an inclined plate 41 attached to the upper surface thereof, and a pair of left and right anti-slip materials 42 attached to the lower surface thereof.

[0049] (Floor slab cutting and removal process) Next, in the slab replacement method according to this embodiment, a slab cutting and removal process is carried out in which the concrete slabs C2 and C3 are cut and removed by running on the running plate 4 installed in the running plate installation process described above with a concrete cutter 5. Figure 10 is a process explanatory diagram showing the slab cutting and removal process of the slab replacement method according to this embodiment.

[0050] Specifically, in this process, as shown in Figure 10, the running wheels 51 travel on an inclined plate 41 attached to the upper surface of the checker plate 40 of the running board 4, and the diamond blade 50 of the concrete cutter 5 is tilted relative to the vertical plane to form a slope and diagonally cut the intermediate deck C2, shown by the shaded area. This physically prevents the intermediate deck C2 from falling during cutting, and eliminates the need for temporary facilities to prevent it from falling, such as the cantilever deck shoring Sh1 and the intermediate deck shoring Sh2, below the intermediate deck C2, thereby achieving cost reductions.

[0051] Also, as mentioned above, a pair of left and right anti-slip materials 42 are attached to the underside of the checker plate 40, so there is little risk that the checker plate 40 of the running plate 4 will slip out of the recess R1 and fall off when the concrete cutter 5 is running, and cutting work on the intermediate deck C2 can be carried out safely.

[0052] Furthermore, in this process, as shown in Figure 10, runaway prevention material 6 is attached to the upper surface of the checker plate 40 of the running board 4, so there is little risk of the concrete cutter 5 running away or falling off even if there is a small clearance between the part where the overhanging deck C1 has been removed and the edge of the checker plate 40. Therefore, in the deck replacement method according to this embodiment, the concrete cutter 5 can safely cut the intermediate deck C2, significantly improving the work efficiency of this process.

[0053] In this process, as shown in Figure 10, similar to the intermediate deck C2, the running wheels 51 run over the checker plates 40 of the running board 4, and the concrete cutter 5 cuts and removes the intermediate deck C3, which is the concrete deck indicated by the shaded area. However, because the aforementioned intermediate deck support Sh2 is installed below the intermediate deck C3 to prevent the end of the intermediate deck on the traffic lane side from dropping, unlike the intermediate deck C2, there is no need to cut diagonally with the diamond blade 50 inclined to the vertical plane. Furthermore, if the intermediate deck C3 is not cut and removed before the intermediate deck C2, there is no problem of a small clearance between the removed part and the edge of the checker plates 40, and therefore there is no need to install the runaway prevention material 6.

[0054] (Upper girder forming process) Next, in the deck replacement method according to this embodiment, as shown in Figure 11, the upper part of the main girder G1, which was left aligned with the deck top surface to make it easier for the concrete cutter 5 to travel in the previous deck cutting and removal process, is chipped off with a chipping machine or the like to form a flat surface on which the precast deck PC1 can be placed, in a girder upper part forming process. Figure 11 is a process explanatory diagram showing the upper part of the girder forming process of the deck replacement method according to this embodiment.

[0055] (Stirrup stretching process) Next, in the deck slab replacement method according to this embodiment, a stirrup extension process is carried out in which the stirrup Sr of the main girder G1 is extended and the mechanical anchor Mf is joined, as shown in Figures 12 and 13. Figure 12 is a process explanatory diagram showing the stirrup extension process of the deck slab replacement method according to this embodiment.

[0056] Specifically, as shown in Figure 12, a crimping machine is used to crimp steel pipes Sp onto the stirrups Sr exposed from the top of the main girder G1, and the steel bars are extended, and mechanical anchors Mf are joined to the ends of the extended steel bars. As mentioned above, this is to maintain the load-bearing capacity of the existing structure of bridge B1, which is a composite girder bridge, while also making it possible to maintain the necessary load-bearing performance in the event of the swinging of the web of main girder G1.

[0057] In this step, as shown in FIG. 12, it is preferable to also install anti-slip reinforcing bars As on the top surface of the main girder G1 by post-construction using chemical anchors (registered trademark) or the like.

[0058] (Pedestal installation process) In the deck slab replacement method according to this embodiment, a base installation step of installing the base 3 on the top surface of the main girder G1 is carried out simultaneously with the stirrup extension step (see FIG. 3).

[0059] Specifically, as shown in Figure 3, a time-hardening material 32 such as mortar or adhesive is applied to the block portion 31 at the bottom of the base 3, and pressed against the uneven upper surface where the aggregate of the main girder G1 is exposed, thereby fixing the upper surface of the steel plate portion 30 at the top of the base 3 so that it is approximately horizontal.

[0060] (Precast deck erection process) Next, in the deck replacement method according to this embodiment, a precast deck installation step is carried out in which a precast deck is installed on the bridge girder from which the concrete has been removed in the joint concrete removal step, as shown in Fig. 13. Fig. 13 is a process explanatory diagram showing the precast deck installation step of the deck replacement method according to this embodiment.

[0061] Specifically, in this process, as shown in Figure 13, the precast deck slab PC1 is erected in a horizontal position where the height adjustment bolt 2 of the deck slab installation height adjustment mechanism 1 abuts the upper surface of the steel plate portion 30 of the base 3 installed in the base installation process, and then the installation height of the precast deck slab PC1 is adjusted using the height adjustment bolt 2 so that the upper surface of the precast deck slab PC1 is approximately horizontal or has a predetermined water gradient.

[0062] After that, non-shrinkage mortar is filled between the precast deck PC1 and the main girder G1, and concrete is poured into the cutout portion Np of the precast deck PC1 and the joints (not shown) between the precast deck PC1, thereby completing the deck replacement work of the deck replacement method of this embodiment, in which the deteriorated cast-in-place concrete deck portion is removed and replaced with the precast deck PC1 for renewal.

[0063] According to the deck installation height adjustment mechanism 1 and deck replacement method using the same according to the embodiment of the present invention described above, the precast deck PC1 is erected in a planar position where the height adjustment bolts 2 of the deck installation height adjustment mechanism 1 abut against the upper surface of the steel plate portion 30 of the base 3 installed in the base installation process, and then the installation height of the precast deck PC1 is adjusted using the height adjustment bolts 2 so that the upper surface of the precast deck PC1 is approximately horizontal or has a predetermined water gradient. This makes it easy to adjust the height on the upper surface of the main girder G1, which has large irregularities where the aggregate is exposed, and also eliminates the problem of the abutting concrete collapsing when the height adjustment bolts 2 are rotated during adjustment, causing the position of the precast deck PC1 to shift, thereby allowing the planar position of the deck to be adjusted with high precision.

[0064] Furthermore, according to the deck installation height adjustment mechanism 1 and deck replacement method, the base 3 is composed of two parts: a steel plate portion 30 and a block portion 31. The steel plate portion 30, which is made of a steel or iron plate, resists friction when the height adjustment bolt 2 rotates when adjusting the height of the precast deck PC1, and the block portion 31, which is made of a mortar block, reduces weight to ensure space in the vertical direction, and reduces the protruding length of the height adjustment bolt 2, thereby shortening the work time required to screw in and remove the height adjustment bolt 2.

[0065] The above has described in detail the deck slab installation height adjustment mechanism 1 according to an embodiment of the present invention and the deck slab replacement method using the same. However, the above-described and illustrated embodiments are merely specific embodiments for carrying out the present invention. Therefore, the technical scope of the present invention should not be interpreted as being limited by these. [Explanation of symbols]

[0066] 1: Deck installation height adjustment mechanism 2: Height adjustment bolt 21: Height adjustment bracket 22: Guide sheath 3: Base 30: Iron plate section 31: Block section 32: Time-hardening material 4: Running board 40: Checker plate 41: Inclined plate 42: Anti-slip material 5: Concrete cutter (floor slab cutting device) 50: Diamond Blade 51: Running wheels 6:Escape prevention material B1: Bridge G1: Main girder (bridge girder) Sr: Stirrup Sp: Steel pipe Mf: Mechanical fixing body SC: Synthesis part R1: Recess C1: Cantilevered deck (concrete deck) C2: Intermediate floor slab (concrete floor slab) C3: Intermediate floor slab (concrete floor slab) Wb: Wall parapet Pf: Temporary protective fence (temporary facility) Sh1: Support for cantilever deck (temporary facility) Sh2: Intermediate deck support (temporary facility) PC1: Precast deck Np: Notch

Claims

1. A floor slab installation height adjustment mechanism that adjusts the installation height when erecting a precast floor slab, The precast floor slab is provided with a plurality of height adjustment bolts that are threadedly engaged with female thread jigs embedded in the precast floor slab and can be freely protruded and retracted from the underside of the precast floor slab, and a plurality of pedestals provided at positions that come into contact with the lower ends of the plurality of height adjustment bolts. A deck installation height adjustment mechanism characterized by:

2. The base is made up of an iron plate portion made of a steel plate or iron plate and a block-shaped portion for securing a certain space. The deck installation height adjustment mechanism according to claim 1 .

3. A deck replacement method that replaces the deteriorated concrete deck portion of a bridge made of composite girders with a new precast deck, A joint concrete removal process in which concrete from the composite parts of the bridge girder, which is a composite girder, is chipped off and removed with a water jet; a precast deck erection step of erecting the precast deck on the bridge girder from which the concrete has been removed in the joint concrete removal step, In the precast deck erection step, the deck installation height adjustment mechanism according to claim 1 or 2 is used to erect the precast deck so that the height adjustment bolts are positioned on the plurality of pedestals installed on the bridge girders from which the concrete has been removed by the water jet in the joint concrete removal step, and the installation height of the precast deck is adjusted with the height adjustment bolts. A deck replacement method characterized by the following.

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