Method of removing floor slab of composite girder bridge and reinforcing member used therefor

Abstract

To provide a method for removing a composite girder bridge floor slab and a reinforcing member used for the same, which greatly shorten a work period after a road is closed by removing concrete of a floor slab hump part in advance by a water jet while using the road and successively reinforcing the floor slab.SOLUTION: A method of removing a floor slab of a composite bridge girder according to the present invention includes the steps of removing concrete in a predetermined section from a side of a floor slab hump portion of a floor slab within a specific height range from an upper surface of a girder flange of a bridge girder while maintaining an upper surface of the floor slab with a water jet, installing a reinforcing member in the section from which the concrete is removed, and removing the reinforcing member to remove the floor slab after stopping traffic on the floor slab. The specific height is 30 ± 5mm from the upper surface of the girder flange, and the concrete of a floor slab haunch part in a section for removing the floor slab is removed by repeating a stage for removing the concrete in a predetermined section and a stage for installing the reinforcing member while changing the section.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for removing the deck of a composite girder bridge and a reinforcing member used for this purpose, and in particular to a method for removing the deck of a composite girder bridge using a water jet to remove the concrete from the haunch of the deck while the road is still in use, and then reinforcing it in stages, thereby significantly shortening the work period after road closure and the reinforcing member used for this purpose. [Background technology]

[0002] Viaducts are used throughout Japan for road construction, including expressways that have been developed using many viaducts. Many of these have deteriorated over the years and are in need of repair or replacement. When replacing a bridge, one method is to build a new bridge adjacent to the existing bridge while maintaining traffic flow on the existing bridge, and then replace it once it is completed, but this method is not realistic for roads with continuous elevated bridges over long distances, such as expressways. Therefore, the method used is to leave the existing bridge girders in place and replace the deck.

[0003] However, deck slabs are large, heavy structures that are not easy to remove, and are usually cut into transportable pieces for removal. In the case of composite girder bridges, where the bridge girders and deck slabs are fixed together during construction, they are firmly attached to the bridge girders, and cutting and removing the fixed parts to the bridge girders is a time-consuming task. In the past, with such composite girder bridges, the deck slab, excluding the section directly above the bridge girder, was cut into blocks and removed, and the remaining section directly above the bridge girder was mechanically chipped to remove the concrete. This posed various challenges, including restrictions on the size of the deck slab that could be cut, the need to cut both sides of the bridge girder at least along the girder, which meant a long cutting distance was required to remove the deck slab, and noise generated by the chipping process.

[0004] In response to this, technology has been proposed to efficiently separate the fixed parts between the deck and the bridge girder, taking into account the reuse of the bridge girder. Patent Document 1 describes a method for removing bridge decks, in which a high-pressure water jet is used to remove only the concrete from the top surface of the deck along the length of the steel main girders to form a cutting zone narrower than the width of the steel girders, exposing the dowels on the top surface of the steel girders and some of the rebar embedded in the concrete deck in the cutting zone to separate the steel girders from the concrete deck, and cutting the concrete deck into block pieces of the required size, which are then peeled off and removed.

[0005] With this removal method, the fixed parts to the bridge girder can be easily separated by removing the concrete with a water jet, eliminating the need to cut both sides of the bridge girder along the girder, which is expected to improve the efficiency of the removal work. However, whether this removal method or the conventional method is used, it is necessary to suspend vehicle traffic when work begins to remove the deck. Viaducts at key transportation hubs and expressways are part of the arteries of logistics, and even if the deck is to be replaced, closing the road for an extended period of time results in significant economic losses, so it is necessary to shorten the construction period during which the road is closed as much as possible.

[0006] Patent Document 2 describes a bridge deck removal method that involves cutting the haunch portion of the contact point between the concrete deck and the bridge girder and the deck anchors horizontally by applying a sawing wire, disc-shaped blade, water jet, etc. to the cutting point, thereby separating the concrete deck from the bridge girder.It also describes that because the cutting of the haunch portion of the contact point between the concrete deck and the bridge girder is done horizontally, it can be done without stopping traffic. However, because the haunch portion is cut horizontally and separated, the effect of preventing slippage is lost, and there are safety concerns if vehicles are allowed to pass through in this state.

[0007] Patent Document 3 takes into account the issues with Patent Documents 1 and 2 above, and describes a method for removing the deck of a composite girder bridge, in which a predetermined section of concrete is removed from the side of the deck haunch using a water jet while maintaining the top surface of the deck, reinforcing members are installed in the section from which the concrete was removed, traffic on the deck is stopped, and then the reinforcing members are removed to remove the deck, as well as the reinforcing members used for this. According to the deck removal method described in Patent Document 3, the concrete in the deck haunch can be removed while leaving the anti-slip bars in place, and the installation of reinforcing members also suppresses horizontal displacement of the deck. This allows for the process to be carried out before the road is closed to vehicles, etc., and significantly shortens the work period after the road is closed.

[0008] However, some bridges have a structure in which haunch rebars are embedded in addition to shear stop bars in the haunch section, and a new issue has been discovered in which the haunch rebars interfere and make it impossible to install the reinforcing members described in Patent Document 3. Furthermore, the reinforcing members described in Patent Document 3 are attached to the edges of the girder flanges of the bridge girders to reinforce the area around the shear stop bars, but the width of the girder flanges varies depending on the bridge, and as a result, the distance from the edge of the girder flange to the reinforcing shear stop bars varies depending on the location, and a new issue has been discovered in which one type of reinforcing member may not be able to cover all of the problems. Therefore, there is a need for a reinforcing member that can reinforce the anti-slip bars even when haunch reinforcement is used or the width of the girder flange varies depending on the location, and a deck removal method that uses this member to advance the process before the road is closed to vehicles, etc., and that can significantly shorten the work period after the road is closed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-207388 [Patent Document 2] Special Publication No. 06-043682 [Patent Document 3] Japanese Patent Application Publication No. 2019-105031 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the problems with the above-mentioned conventional methods for removing the deck slabs of composite girder bridges, and the object of the present invention is to provide a method for removing the deck slabs of composite girder bridges, and the reinforcing members used in this method, which significantly shortens the work period after road closure, even for deck slabs that include haunch reinforcement or bridge girders where the width of the girder flange varies depending on the location, by removing the concrete from the deck haunch section in advance with a water jet while the road is in use, and then reinforcing it sequentially with thin reinforcing members. [Means for solving the problem]

[0011] The method for removing deck slabs of a composite girder bridge according to the present invention, which has been made to achieve the above-mentioned object, comprises the steps of: removing a predetermined section of concrete around the shear stop bars of the deck slab haunch by water jetting, while leaving the shear stop bars from the sides of the deck slab haunch for the deck slab within a specific height range from the top surface of the girder flange of the bridge girder, while maintaining the top surface of the deck slab so as not to obstruct vehicle traffic; installing and fixing reinforcing members whose maximum height is within the specific height range around the specific shear stop bars in the section from which the concrete has been removed; and, after stopping traffic on the deck slab, removing the reinforcing members, cutting the shear stop bars, and removing the deck slab. The specific height is the height of the girder flange. The concrete is removed from the deck haunch in the section where the deck is to be removed, and the reinforcing member has at least one recess for enclosing a shear stop bar, an injection hole for injecting mortar into the at least one recess, and at least one removal screw hole spaced horizontally from the injection hole. The reinforcing member is removed by using the mortar injected into the recess as a reaction material and pulling it away from the mortar by the pulling force of a removal bolt threaded into the removal screw hole.

[0012] The step of removing a predetermined section of concrete from the deck haunch portion with a water jet preferably includes the steps of: moving the water jet nozzle back and forth in the bridge axis direction to cut and remove concrete from one side of the deck haunch portion of the composite girder bridge until the first row of shear resistance bars is visible; moving the water jet nozzle in a direction perpendicular to the bridge axis between adjacent shear resistance bars to cut and remove concrete up to the other side of the deck haunch portion of the composite girder bridge; and replacing the nozzle with one that sprays at a direction perpendicular to the extension direction to cut and remove concrete between the shear resistance bars arranged in the direction perpendicular to the bridge axis.

[0013] The step of installing the reinforcing member preferably includes the steps of installing at least one back block having a recess facing the back surface of the shear stop bar so that the recess faces the back surface of the shear stop bar; combining a main block having at least one recess corresponding to the recess of the at least one back block for enclosing the shear stop bar with the at least one back block so that the recess encloses the shear stop bar; and injecting mortar into the space enclosing the shear stop bar to fix the shear stop bar and the reinforcing member.

[0014] It is preferable that the step of removing the reinforcing members, cutting the anti-slip bars and removing the deck slab includes the steps of removing the reinforcing members, cutting the deck slab into blocks, cutting the anti-slip bars other than those necessary to secure the deck slab block, and cutting the remaining anti-slip bars while lifting the deck slab block and transporting the deck slab block.

[0015] The reinforcing member of the present invention, which has been made to achieve the above-mentioned object, is a reinforcing member that reinforces around the above-mentioned shear stop bar, and has a main body block that includes at least one recess for enclosing the shear stop bar, an injection hole for injecting mortar into the at least one recess, and at least one removal screw hole horizontally spaced from the injection hole, and at least one back block that faces the at least one recess in the main body block and forms a space for enclosing the shear stop bar, and is characterized in that the maximum height of the reinforcing member formed by combining the main body block and the back block is less than the specific height range for removing concrete. [Effects of the Invention]

[0016] According to the composite girder bridge deck removal method of the present invention, concrete can be removed from the haunch of a specific height range of a deck while maintaining the deck's upper surface. This involves repeatedly cutting and removing concrete and installing reinforcement members at intervals from the side of the deck's haunch. This eliminates the need to close the road to traffic during this process, and as a result of this preparatory work, the construction period during which road closures are required can be significantly shortened. The reinforcement members used here are thin, with a reduced overall height to allow installation in the narrow space between the top surface of the bridge girder's girder flange and the underside of the deck formed by removing the concrete. This allows installation without being affected by the haunch reinforcement. Furthermore, since they are not fixed to the edge of the girder flange, installation is not affected by the width of the girder flange. By using thin reinforcement members, the height range of concrete removal is limited, thereby reducing the stress caused by bending moments on the shear connectors exposed through the concrete, thereby allowing for a reduced level of reinforcement. Furthermore, according to the method for removing deck slabs of a composite girder bridge of the present invention, there is no need to cut both sides of the bridge girder along the girder, and the size of the deck slab blocks that are cut and excised can be made larger, so the total cutting distance of the deck slab by the road cutter can be shortened, thereby shortening the construction period.

[0017] According to the method for removing the deck slab of a composite girder bridge of the present invention, the reinforcing members are fixed to the shear stop bars with mortar, and therefore, by removing the concrete around the shear stop bars, the amount of bending stress acting on the shear stop bars is reduced, and safety for vehicle passage can be ensured even after the concrete around the shear stop bars is removed. Furthermore, the reinforcing member of the present invention is composed of multiple blocks, is easy to assemble and disassemble, and can be reused, thereby preventing unnecessary increases in costs associated with removing the deck of a composite girder bridge. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram illustrating a schematic structure of a composite girder bridge before applying a method for removing a deck slab of a composite girder bridge according to an embodiment of the present invention. [Figure 2] 1 is a diagram illustrating a method for removing concrete from a deck haunch portion using a water jet according to an embodiment of the present invention. FIG. [Figure 3] 1 illustrates a reinforcing member according to an embodiment of the present invention. [Figure 4] 10A to 10C are diagrams illustrating a method for installing a reinforcing member according to an embodiment of the present invention. [Figure 5] 10A to 10C are diagrams illustrating a method for removing a reinforcing member according to an embodiment of the present invention. [Figure 6] 1 is a flowchart illustrating a method for removing a deck slab of a composite girder bridge according to an embodiment of the present invention. [Figure 7] 1 is a flowchart illustrating a method for removing concrete from a deck haunch using a water jet according to an embodiment of the present invention. [Figure 8] 4 is a flowchart illustrating a method for installing a reinforcing member according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, a specific example of an embodiment for carrying out the method for removing a deck slab of a composite girder bridge according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic structure of a composite girder bridge before application of a method for removing a deck slab of a composite girder bridge according to an embodiment of the present invention.

[0020] Referring to Figure 1, composite girder bridge 1 comprises steel bridge girder 2, deck slab 3, deck haunch portion 4, which is a part of deck slab 3 but has a side that slopes up from steel bridge girder 2 to deck slab 3, and multiple shear connectors 5 welded and arranged in a matrix on steel bridge girder 2. When shear connectors 5 are arranged closely together, they are generally installed at intervals of approximately 100 mm in both the bridge axis direction and the direction perpendicular to the bridge axis. In the composite girder bridge 1, the steel bridge girder 2 and the deck slab 3 are integrated with poured concrete so that the deck slab 3 installed on the steel bridge girder 2 also plays a part of the role of the bridge girder. At this time, the shear retaining bars 5 arranged on the steel bridge girder 2 work to increase the joint strength between the steel bridge girder 2 and the deck slab 3.

[0021] On the other hand, when a bridge is used for a long period of time, the deck 3 deteriorates. However, in the case of a composite girder bridge 1, the steel bridge girder 2 and deck 3 are firmly joined by shear stop bars 5, which makes it difficult to replace the deck 3. For this reason, replacing the deck 3 takes a long time and is generally carried out after vehicular traffic has been closed, which is an important issue as it has a large social impact due to road closures.

[0022] The method for removing the deck slab of a composite girder bridge according to an embodiment of the present invention takes into account these issues with the composite girder bridge 1, and involves removing concrete in a specific height range around the shear stop bars 5 while temporarily reinforcing with easily removable reinforcing members, thereby removing the concrete around the shear stop bars 5 in sections where the deck slab 3 needs to be replaced, without stopping vehicle traffic, and proceeding with the process until the deck slab 3 is in a state where it can be easily removed. By proceeding with the preparatory work in this way, it becomes easier to remove the deck slab 3 after vehicle traffic is stopped, and as a result of shortening the construction period, the period of vehicle road closure can also be shortened, reducing the social impact.

[0023] A method for removing concrete around the shear retainer 5 will be described below with reference to FIG. FIG. 2 is a diagram illustrating a method for removing concrete from the deck haunch portion 4 by using a water jet according to an embodiment of the present invention. Referring to Figure 2, the method of removing concrete is shown in three stages (a) to (c). For ease of viewing, the location where the concrete is to be removed is shown in a plan view, with the deck slab 3 extending above it omitted. When using a water jet to cut an inclined surface such as the side of the deck haunch 4, the jetted water is reflected at an angle, dispersing the water pressure that contributes to cutting, making cutting inefficient. For this reason, the side of the deck haunch 4 to be cut is mechanically ground in advance to make it a vertical surface.

[0024] A water jet device 10 is installed along the steel bridge girder 2 to remove the concrete from the deck haunch 4. When removing the deck 3 of the composite girder bridge 1, scaffolding is installed for the work, and in this embodiment, a hanging scaffolding is installed and the water jet device 10 is installed on the hanging scaffolding. Waterproofing measures are taken on the hanging scaffolding to prevent the water used by the water jet device 10 from falling below the hanging scaffolding, and a dedicated drain outlet is also installed on the hanging scaffolding to collect water containing concrete powder from the cutting process.

[0025] The water jet device 10 includes a traveling platform 11 for moving the water jet nozzle in the bridge axis direction, a bridge axis moving platform 12 mounted on the traveling platform 11 so as to be movable along the traveling platform 11, a perpendicular direction platform 13 mounted on the bridge axis moving platform 12 and extending in a direction perpendicular to the bridge axis, a perpendicular direction moving platform 14 mounted on the perpendicular direction platform 13 so as to be movable along the perpendicular direction platform 13, and water jet nozzles (15, 16) mounted on the perpendicular direction moving platform 14 so as to extend in a direction perpendicular to the bridge axis.

[0026] The water jet nozzles (15, 16) can be moved in the bridge axis direction and perpendicular to the bridge axis direction by the bridge axis moving platform 12 and the perpendicular direction moving platform 14. The water jet nozzles (15, 16) can be freely moved on a plane corresponding to the movable areas of the bridge axis moving platform 12 and the perpendicular direction moving platform 14 by a control device (not shown). In addition, as will be explained below, the water jet nozzles (15, 16) can be switched between nozzles (15, 16) of different shapes to be used in relation to the position where the concrete is to be cut.

[0027] Referring to Figure 2(a), the water jet nozzle is moved back and forth in the bridge axis direction to cut concrete on one side of the deck haunch portion 4 of the composite girder bridge 1 until the first row of shear retaining bars 5 becomes visible. In this case, the water jet nozzles (15, 16) use a forward jet nozzle 15 that sprays water in the extension direction of the nozzle. In this embodiment, the forward jet nozzle 15 is configured to spray high-pressure water of approximately 200 MPa in a direction toward the central axis of the extension direction of the forward jet nozzle 15 or while rotating at a specific angle relative to the central axis in the extension direction.

[0028] The process of cutting and removing the concrete from the deck slab haunch 4 is carried out as a preparatory step for removing the deck slab 3, but removing the concrete from the deck slab haunch 4 over a long section at a time in order to carry out this process without stopping traffic on the deck slab 3 could result in strength problems. Therefore, in this embodiment, predetermined sections are set, the concrete from the deck slab haunch 4 is removed for each predetermined section, and the removed section is temporarily reinforced with reinforcing members. The predetermined sections are set based on structural analysis to determine the limit of the section range where removing the concrete from the deck slab haunch 4 will not impede traffic on the deck slab 3, and the section is set so as not to exceed this limit.

[0029] As described below, the reinforcing member is attached by being sandwiched between the top surface of the steel bridge girder 2 and the deck slab 3. Therefore, the position where the concrete is removed from the deck haunch 4 is adjusted to include the area directly above the steel bridge girder 2. Because the deck haunch 4 expands laterally and the amount of concrete to be removed increases as the distance from the top surface of the steel bridge girder 2 increases, it is preferable to remove concrete closer to the top surface of the steel bridge girder 2 for work efficiency reasons. The narrower the height range from which concrete is removed, the more effectively the bending moment applied to the shear connectors 5 in the removed area can be reduced. Therefore, it is preferable to remove as narrow a range of concrete as possible. However, due to limitations in the cutting range of the water jet, in this embodiment, the range is set to 30 ± 5 mm from the top surface of the steel bridge girder 2. By narrowing the height range from which concrete is removed, the reinforcing member does not need to have high reinforcing performance. Furthermore, the reinforcing member does not need to have a structure that sandwiches the girder flange.

[0030] After cutting and removing the concrete within a specific height range from the top surface of the steel bridge girder 2 until the first row of shear resistance bars 5 in a specified section becomes visible, i.e., within a range of 30±5 mm in this embodiment, as shown in Figure 2(b), the water jet nozzle 15 is moved perpendicular to the bridge axis between adjacent shear resistance bars 5 to cut and remove the concrete up to the other side of the deck haunch portion 4 of the composite girder bridge 1. The water jet nozzle used at this time is the forward jet nozzle 15, as in FIG. 2(a).

[0031] As the concrete cutting perpendicular to the bridge axis progresses and reaches the other side of the deck haunch 4, the water jet will be released into the air with the same force, so before cutting begins in the direction perpendicular to the bridge axis, a drainage means combining a dam wall to prevent the water jet from being released into the air even if it penetrates the concrete and a drainage gutter to collect and drain the blocked water is installed on the other side of the deck haunch 4 of the composite girder bridge 1. The drainage means combining a dam wall and drainage gutter also serves to reduce the noise that cuts through the air when the water jet is released into the air.

[0032] After cutting and removing the concrete between the adjacent shear retaining bars 5 in the bridge axis direction, concrete remains between the shear retaining bars 5 aligned perpendicular to the bridge axis, forming a wall-like shape perpendicular to the bridge axis. This part is difficult to cut because the front jet nozzle 15 cannot apply a water jet with sufficient pressure.

[0033] Therefore, in the next step, as shown in Figure 2(c), the forward jet nozzle 15 is replaced with a side jet nozzle 16 that sprays a water jet perpendicular to the extension direction, and the concrete between the shear retaining bars 5 arranged perpendicular to the bridge axis is cut and removed. In this case too, the side injection nozzle 16 is moved perpendicular to the bridge axis to cut and remove the concrete between the shear bars 5.

[0034] 2(a) to 2(c) as described above, it is possible to remove concrete within a specific height range from the top surface of the steel bridge girder 2 around the shear retaining bars 5 in a specified section. By cutting and removing the concrete with a water jet, it is possible to remove the concrete with less noise and without scattering dust compared to the conventional mechanical chipping method. After removing the concrete around the shear retaining bars 5 in the specified sections, temporary reinforcement is quickly carried out using reinforcing members.

[0035] Figure 3 shows a reinforcing member according to an embodiment of the present invention. Figure 3(a) is a plan view of the reinforcing member 20, and Figure 3(b) is a cross-sectional view taken along line A-A' shown in Figure 3(a). Figure 3(c) shows a modified example of the reinforcing member 20 shown in Figure 3(a). Referring to FIGS. 3(a) and 3(b), the reinforcing member 20 includes a main block 21 and a rear block 31 as main components.

[0036] The main body block 21 has at least one recess 22 for enclosing the shear stop bar 5, an injection hole 25 for injecting mortar into the at least one recess 22, and at least one removal screw hole 27 horizontally spaced from the injection hole 25. The main body block 21 also has a fixing screw insertion hole 28 for connecting to the back block 31, so that it can be used in combination with the back block 31. The reinforcing member 20 shown in FIG. 3(a) is an embodiment of the reinforcing member 20 having two recesses 22, as an example.

[0037] The reinforcing member 20 is intended to temporarily reinforce the anti-slip bars 5 during the preparatory work for removing the deck slab 3, which is carried out without stopping vehicle traffic, and is the first to be removed during the removal work of the deck slab 3 after vehicle traffic is stopped, so it is required to be easily removable. Therefore, the main body block 21 has a tapered portion 26 on the top surface to make it easy to remove, and also has a removal screw hole 27 for screwing in a removal bolt that removes the main body block 21 by pulling it back using mortar that has been poured into the recess 22 and hardened as a reaction material.

[0038] The rear block 31 faces at least one recess 22 of the main body block 21 and has a recess 33 for forming a space surrounding the anti-slip bars 5. Like the main body block 21, the upper surface of the rear block 31 has a tapered portion 34 for easy removal. Both the tapered portion 26 of the main body block 21 and the tapered portion 34 of the rear block 31 are inclined downward toward the recesses (22, 33), and each has a shape that is lowest on the boundary surface where the main body block 21 and the rear block 31 meet. The rear block 31 further includes fixing screw holes 35 at positions corresponding to the fixing screw insertion holes 28 of the main body block 21 so that the rear block 31 can be combined and fixed to the main body block 21 .

[0039] As mentioned above, the reinforcing member 20 does not require an attachment structure to the bridge girder, so it is installed in a narrow space where concrete within a specific height range has been removed using a water jet. Therefore, the installation height of the reinforcing member 20 must be within a specific height range. In this embodiment, the specific height is 30±5 mm, so the total height of the reinforcing member 20 is at most 25 mm.

[0040] The reinforcing member 20 shown in FIG. 3(a) has two recesses 22 whose pitch is dimensioned to match the pitch of the shear stop bars 5 so as to reinforce the area around two adjacent shear stop bars 5. However, the pitch of the shear stop bars 5 in existing composite girder bridges 1 is not necessarily constant and may vary depending on the location. Therefore, in the reinforcing member 20 having two recesses 22 as shown in FIG. 3(a), the pitch may not necessarily match the pitch of the shear stop bars 5. Therefore, in the embodiment of the present invention, a reinforcing member 20-1 with only one recess 22 as shown in FIG. 3(c) is also used in the part where the pitch does not match the pitch of the shear stop bars 5.

[0041] Like the reinforcing member 20, the reinforcing member 20-1 also includes a main block 21 and a rear block 31, and has an overall height of 25 mm at most. In the reinforcing member 20-1 shown in Figure 3(c), in order to make the entire member smaller and lighter, the fixing screw insertion holes 28 and the removal screw holes 27 are provided coaxially in the same location, and the removal screw holes 27 are provided by cutting female threads into the fixing screw insertion holes 28, but the fixing screw insertion holes 28 and the removal screw holes 27 may also be provided separately and spaced apart in the horizontal direction.

[0042] 4A and 4B are diagrams for explaining a method for installing a reinforcing member according to an embodiment of the present invention, in which FIG. 4A shows an intermediate stage of attaching the main body block 21, and FIG. 4B shows the final stage of installing the reinforcing member 20. Referring to Figure 4(a), the state is shown in which back blocks 31 are installed on the back surfaces of two of the shear retaining bars 5 exposed after the concrete has been removed, which are close to the side ends of the steel bridge girder 2, and the main block 21 is installed so as to combine with the installed back blocks 31.

[0043] When installing the back block 31, the recess 33 of the back block 31 is positioned so that it faces the shear stop bars 5, and the main block 21 is attached so that the recess 22 surrounds the shear stop bars 5 and faces the recess 33 of the back block 31. For this reason, it is preferable to form the pitch of the recesses 33 of the back block 31 and the pitch of the recesses 22 of the main block 21 to match the pitch of the shear stop bars 5. However, in the case of a composite girder bridge 1 in which the installation pitch of the shear stop bars 5 varies depending on the location, in places where the pitch of the shear stop bars 5 and the pitch of the recesses 22 of the main block 21 do not match, a reinforcing member 20-1 with one recess 22 as shown in Figure 3(c) is used.

[0044] In either case, the main body block 21 is pushed toward the back block 31 so as to surround the anti-slip bars 5 with the recesses 22, and fixing screws for connecting to the back block 31 are inserted through the fixing screw insertion holes 28 to secure the blocks together. Next, as shown in FIG. 4(b), mortar 30 is injected into the space formed by the recesses 22 and 33 through the injection hole 25 using a mortar injection pipe 29 and allowed to harden. The mortar 30 hardens to a strength of 40 N / mm 2 By using a plastic, non-shrinking material that develops its strength, the required strength can be obtained in a short period of time.

[0045] The injection of mortar 30 is not limited to the spaces formed by the recesses 22 and 33, but is also carried out so as to fill the gaps between the concrete and the upper parts of the reinforcing members (20, 20-1), including the tapered portion 26 of the main block 21 and the tapered portion 34 of the rear block 31. Although not shown, in this embodiment, a thin aluminum plate is installed around the outer periphery of the reinforcing members (20, 20-1) as a gable frame to prevent mortar 30 overflowing from the spaces formed by the recesses 22 and 33 from dripping around the reinforcing members (20, 20-1) during the injection of mortar 30. This keeps the injected mortar 30 between the reinforcing members (20, 20-1) and the ground concrete surface on the upper part of the reinforcing members (20, 20-1), creating a tightly packed state of the mortar 30.

[0046] After the mortar 30 has hardened, the anti-slip bars 5 and the reinforcing members (20, 20-1) are integrated by the mortar 30, and the gaps above the reinforcing members (20, 20-1) are also filled with mortar 30, so that the deck slab 3 has sufficient strength to be used for vehicle traffic until it is removed.

[0047] When a certain section of concrete is removed around the shear connector 5, the deck slab 3 and steel bridge girder 2 in the section where the concrete was removed will each attempt to deform independently in response to external loads such as vehicle traffic. As a result, not only vertical loads but also bending loads due to relative displacement between the steel bridge girder 2 and deck slab 3 will be applied to the shear connector 5, raising concerns that the shear connector 5 may yield and become structurally unstable. For this reason, the shear connector 5 and reinforcing members (20, 20-1) are integrated with mortar 30 to suppress the occurrence of bending stress acting on the shear connector 5 and ensure safety. As described above, temporary reinforcement of the specified section from which the concrete has been removed is completed by installing reinforcing members (20, 20-1) on a row of anti-slip bars 5 near the side end of the steel bridge girder 2.

[0048] Figure 5 is a diagram illustrating a method for removing a reinforcing member according to an embodiment of the present invention, where Figure 5(a) shows the positional relationship between the reinforcing member and the holes and screws of the reinforcing member removal tool, and Figure 5(b) shows a method for removing the reinforcing member using the reinforcing member removal tool. Referring to Figure 5(a), the upper side shows the reinforcing member 20 installed between the steel bridge girder 2 and the deck haunch portion 4, and the lower side shows a reinforcing member removal tool 40 for removing the reinforcing member 20. The reinforcing member 20 is installed in a narrow space where the concrete of the deck haunch 4 has been cut away within a specific height h range from the top surface of the girder flange 50 at the top of the constituent girder bridge 2. However, due to variations in the processing accuracy of the water jet, when the reinforcing member 20 is installed at height H, a gap exists between it and the underside of the deck haunch 4, but when the mortar 30 is injected, it is injected so that it overflows into the top of the recess 22 as well, so the space between the underside of the deck haunch 4 and the top surface of the reinforcing member 20 is filled and hardened by the mortar 30.

[0049] When reinforcing member 20 is viewed from the side of main body block 21, fixing screw insertion holes 28, injection holes 25, and removal screw holes 27 are arranged at intervals in the horizontal direction. Reinforcing member removal tool 40 is a plate-shaped tool that has reaction bolt screw holes 41 at a position opposite injection hole 25 and removal bolt insertion holes 42 at a position opposite removal screw holes 27.

[0050] Next, a method for removing the reinforcing member will be described with reference to Figure 5(b). To remove the reinforcing member 20, the fixing screws inserted into the fixing screw insertion holes 28 are removed to release the connection between the main body block 21 and the rear block 31. In this state, a reinforcing member removal tool 40, with a reaction bolt 43 screwed into the reaction bolt screw hole 41, is placed facing the main body block 21. Mortar 30 is injected through the injection hole 25 of the main body block 21 and hardened. However, if the mortar 30 hardens inside the injection hole 25, it will need to be removed before the main body block 21 can be reused again. Therefore, in this embodiment, a cylindrical anti-clogging member is inserted into the injection hole 25 after the mortar 30 has been injected, and the mortar 30 is allowed to harden while preventing any residue from remaining in the injection hole 25.

[0051] When removing the main body block 21, the anti-clogging member is removed, leaving the injection hole 25 hollow, and the hardened mortar 30 inside the recess 22 remains at the end of the injection hole 25. A long reaction bolt 43 is used so that its tip can reach the mortar 30 deep inside the injection hole 25. With the tip of the reaction bolt 43 abutting against the mortar 30 at the end of the injection hole 25, a removal bolt 44 is inserted through the removal bolt insertion hole 42 and threaded into the removal screw hole 27 of the main body block 21. The removal bolt gradually penetrates into the main body block 21, but when the head of the removal bolt 44 abuts against the plate-shaped portion of the reinforcement member removal tool 40, the penetration stops and, instead, the mortar 30 acts as a reaction member to pull the main body block 21 back. As a result, the main body block 21 is pulled away from the mortar 30, making it easy to remove.

[0052] The reinforcing member 20 is easy to install and remove because it has a combined structure of a main block 21 and a rear block 31, and can be reused after removal, so once the required number is produced, increases in construction costs can be prevented in future construction works. The method for removing the reinforcing member 20 has been explained above, but the same applies to the reinforcing member 20-1, which has only one recess 22. When using the reinforcing member 20-1, a dedicated reinforcing member removal tool 40 is also used that is compatible with the injection hole 25 and removal screw hole 27 of the reinforcing member 20-1.

[0053] FIG. 6 is a flowchart illustrating a method for removing a deck slab of a composite girder bridge according to an embodiment of the present invention. 6, the work of removing the deck 3 of the composite girder bridge 1 involves removing the concrete from the deck haunch 4 with a water jet device 10 in step S610 as a preparation step while the road remains in service, and then temporarily reinforcing the area from which the concrete was removed by installing reinforcing members (20, 20-1) in step S620. The removal of the concrete from the deck haunch 4 and the installation of the reinforcing members (20, 20-1) will be described in detail below with reference to Figures 7 and 8.

[0054] FIG. 7 is a flowchart illustrating a method for removing concrete from the deck haunch portion 4 by using a water jet according to an embodiment of the present invention. The flowchart in Figure 7 assumes that before concrete removal begins, a water jet device 10 equipped with a bridge axial moving platform 12 and a transverse moving platform 14, and capable of freely moving the nozzle along the bridge axial direction and perpendicular to the bridge axis, has been installed on the side of the deck haunch 4 of the composite girder bridge 1. Also, as mentioned above, in order to ensure that the water jet effectively contributes to cutting, it is assumed that the sloped portion of the side of the deck haunch 4 has been mechanically chipped in advance to produce a vertical surface so that the water jet will hit it perpendicularly.

[0055] In step S710, the water jet nozzle is moved back and forth in the bridge axis direction to cut and remove concrete from one side of the deck haunch 4 of the composite girder bridge 1 until the first row of shear resistance bars 5 is visible. The nozzle is a forward injection nozzle 15 that sprays the water jet in the nozzle extension direction. However, the water jet used in step S710 is not for general use in cutting the workpiece, but rather a forward injection nozzle 15 that sprays the water jet to remove concrete over a specific width in the vertical direction in order to secure space for passing the nozzle between the shear resistance bars 5 and for installing reinforcing members (20, 20-1).

[0056] Concrete removal from the deck haunch 4 is carried out from the side of the deck 3 while maintaining the top surface of the deck 3, so as not to interfere with vehicle traffic on the deck 3. To avoid strength problems, a specified section is identified where concrete removal can be performed at one time, and the work is carried out within that specified section.

[0057] Once the concrete within a specific height range has been cut and removed from the top surface of the girder flange 50 of the steel bridge girder 2 until the first row of shear retarding bars 5 in the specified section is visible, the nozzle is used as is without being replaced, and in step S720 the water jet nozzle is moved perpendicular to the bridge axis between adjacent shear retarding bars 5, cutting and removing concrete within the same specific height range up to the other side of the deck haunch portion 4 of the composite girder bridge 1. At this time, the nozzle may not move in the bridge axis direction but may move only perpendicular to the bridge axis, or it may move back and forth between adjacent shear retarding bars 5 in the direction perpendicular to the bridge axis.

[0058] The removal of concrete between adjacent shear stop bars 5 is repeated for each row, and once the concrete between adjacent shear stop bars 5 in the bridge axis direction within a specified section has been cut and removed, in step S730 the forward jet nozzle 15 is replaced with a side jet nozzle 16 that sprays water jets perpendicular to the extension direction, and the concrete within a specific height range between the shear stop bars 5 arranged perpendicular to the bridge axis is cut and removed. At this time, the side jet nozzle 16 is moved perpendicular to the bridge axis to cut and remove the concrete between the shear stop bars 5. The concrete between the shear stop bars 5 arranged perpendicular to the bridge axis is removed row by row, and concrete removal ends when the removal of concrete around the shear stop bars 5 within a specified section has been completed (step S740).

[0059] FIG. 8 is a flowchart illustrating a method for installing a reinforcing member according to an embodiment of the present invention. 8, in step S810, back blocks 31 of the reinforcing members (20, 20-1) are installed on the back of the shear stop bars 5. The reinforcing members (20, 20-1) are installed on one row of shear stop bars 5 near the side end of the steel bridge girder 2. In this embodiment, one reinforcing member 20 is installed for every two adjacent shear stop bars 5, or in areas where the pitch of the recesses 22 of the reinforcing member 20 does not match the pitch of the shear stop bars 5, a reinforcing member 20-1 with one recess 22 is installed.

[0060] In step S820, the main body block 21 of the reinforcing member (20, 20-1) is aligned with the back block 31, and the recesses 22 of the main body block 21 are positioned so as to surround the anti-slip bars 5 and face the recesses 33 of the back block 31, and then the two are fixed together with fixing screws. This creates spaces that individually surround the anti-slip bars 5.

[0061] Next, in step S830, mortar 30 is injected into the space surrounding the shear stop bars 5 through the injection holes 25 of the main block 21 and allowed to harden, fixing the shear stop bars 5 and the reinforcing members (20, 20-1). At this time, the injected mortar 30 is injected so that it overflows onto the top of the reinforcing members (20, 20-1) and fills the gap between the reinforcing members (20, 20-1) and the concrete located on top of the reinforcing members (20, 20-1). As a result, the reinforcing members (20, 20-1) and the mortar 30 filled on top of the reinforcing members (20, 20-1) play a role in bearing the load from the deck 3 above. When the installation of the reinforcing members (20, 20-1) is completed for all of the shear stoppers 5 in one row near the side end of the steel bridge girder 2 within a predetermined section, the installation of the reinforcing members (20, 20-1) is completed (Step S740).

[0062] Referring again to Figure 6, after the concrete removal from the deck haunch 4 and the installation of the reinforcing members 20, 20-1 described above, in step S630, it is confirmed that the concrete removal from the deck haunch 4 and the installation of the reinforcing members 20, 20-1 in the deck removal section are complete. Steps S610 and S620 are performed in predetermined section units set based on structural analysis. Since the deck removal section is usually longer than the predetermined section, the concrete removal from the deck haunch 4 and the installation of the reinforcing members 20, 20-1 are repeated in predetermined section units until the installation of the reinforcing members 20, 20-1 is completed for the entire deck removal section. The period from stage S610 to stage S630 is a preparation period for removing the deck slab, and this can be done while the upper surface of the deck slab 3 is maintained, allowing it to be used as a road.

[0063] When step S630 is completed, traffic such as vehicles is stopped, and then the reinforcing members (20, 20-1) are removed in step S640. To remove the reinforcing members (20, 20-1), the fixing screws joining the main body block 21 and the back block 31 of the reinforcing members (20, 20-1) are removed, and a reinforcing member removal tool 40 equipped with a reaction bolt is used, and the hardened mortar 30 in the recess 22 is used as a reaction material to tighten the removal bolt inserted into the removal bolt insertion hole 42 of the reinforcing member removal tool 40, thereby pulling the main body block 21 back as if peeling it off from the mortar 30 and removing it.

[0064] Next, in step S650, the deck slab 3 is cut into blocks of a size that is easy to transport, and unnecessary shear stop bars 5 are cut off (step S660). Steps S650 and S660 may be interchanged in the order of the flow, or may be carried out independently and simultaneously in parallel. Unlike conventional methods in which the portion directly above the bridge girder is treated later, in the embodiment according to the present invention, the concrete in the portion directly above the steel bridge girder 2 is removed first, so there is no need to cut the deck slab 3 around the area directly above the steel bridge girder 2, and there are no restrictions on the cutting position of the deck slab 3. Therefore, by cutting the deck slab 3 into blocks of the maximum size that can be carried out, the total cutting distance of the deck slab 3 to be removed can be shortened. The unnecessary shear stop bars 5 in step S660 are shear stop bars 5 other than the minimum necessary shear stop bars 5 to support the deck slab 3 so that it does not slip. The shear stop bars 5 can be cut in a short time even in narrow areas, and furthermore, plasma cutting is used, which does not cause thermal deterioration of the adjacent girder flanges 50.

[0065] Next, in step S670, while the deck block is being lifted by a crane, the remaining shear stop bars 5 are cut and completely separated from the steel bridge girder 2. At this time, too, plasma cutting is used to cut the remaining shear stop bars 5 in a short time. Finally, the separated deck block is removed (step S680), completing deck removal.

[0066] According to the method for removing the deck slab of a composite girder bridge of the present invention, the concrete around the shear stop bars 5 of the composite girder bridge 1, which requires a lot of work to remove, is temporarily reinforced with reinforcing members (20, 20-1) while being removed, thereby creating a condition that makes removal easier without stopping traffic, etc., and ensuring safety in advance. Therefore, the work of removing the deck slab 3 after stopping traffic can be performed in a significantly shorter time than with conventional methods.

[0067] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the technical scope of the present invention. [Explanation of symbols]

[0068] 1 Composite girder bridge 2 Steel bridge girder 3 Floor slab 4 Deck haunch 5. Retaining bars 10 Water jet equipment 11 Traveling stand 12 Bridge axis moving platform 13 Right-angle mounting 14 Right-angle moving platform 15 Forward injection nozzle 16 Side injection nozzle 20, 20-1 Reinforcement member 21 Main body block 22, 33 Recess 35 fixing screw holes 25 Injection hole 26, 34 Tapered section 27 Removal screw hole 28 Fixing screw insertion hole 29 Mortar injection pipe 30 Mortar 31 Back Block 40 Reinforcement member removal tool 41 Reaction bolt screw hole 42 Removal bolt insertion hole 43 Reaction bolt 44 Removal bolt 50-digit flange

Claims

1. While maintaining the upper surface of the deck slab so as not to obstruct vehicle traffic, a predetermined section of concrete is removed around the shear stop bars of the deck slab haunch using a water jet, leaving the shear stop bars on the sides of the deck slab haunch for the deck slab within a specific height range from the upper surface of the girder flange of the bridge girder; Installing and fixing a reinforcing member whose maximum height is within the specified height range around the specific shear stop bar in the section where the concrete has been removed; and after stopping traffic on the deck, removing the reinforcing members, cutting the shear retainers, and removing the deck. The specific height is 30±5 mm from the top surface of the girder flange, The step of removing the concrete in a predetermined section and the step of installing and fixing the reinforcing member are repeated while changing the section, and the concrete of the deck haunch portion in the section where the deck is to be removed is removed; The reinforcing member has at least one recess for enclosing a shear stop bar, an injection hole for injecting mortar into the at least one recess, and at least one removal screw hole horizontally spaced from the injection hole; A method for removing the deck slab of a composite girder bridge, characterized in that the reinforcing member is removed by using the mortar injected into the recess as a reaction material and pulling it away from the mortar by the pulling force of a removal bolt threaded into the removal screw hole.

2. The step of removing a predetermined section of concrete from the deck haunch portion using a water jet includes: a step of moving a water jet nozzle back and forth in the bridge axis direction to cut and remove concrete from one side of the deck haunch of the composite girder bridge until the first row of shear retaining bars is visible; a step of cutting and removing concrete up to the other side of the deck haunch of the composite girder bridge while moving the nozzle of the water jet between adjacent shear retainers in a direction perpendicular to the bridge axis; 2. The method for removing the deck slab of a composite girder bridge as described in claim 1, further comprising the step of replacing the nozzle with a nozzle that sprays in a direction perpendicular to the extension direction and cutting and removing the concrete between the shear-retaining bars arranged in a direction perpendicular to the bridge axis.

3. The step of installing the reinforcing member includes: installing at least one back block having a recess facing the back surface of the shear bar such that the recess faces the back surface of the shear bar; combining a body block having at least one recess corresponding to the recess of the at least one back block for enclosing the shear stop with the at least one back block such that the recess encloses the shear stop; The step of injecting mortar into the space surrounding the shear stopper to fix the shear stopper and the reinforcing member. The method for removing a deck slab of a composite girder bridge according to claim 1, further comprising:

4. The step of removing the reinforcing member, cutting the shear stopper, and removing the deck slab includes: removing the reinforcing member; cutting the deck into blocks; cutting off shear reinforcement bars other than those required for fixing the deck block; and cutting the remaining shear resistance bars while the deck block is lifted, and transporting the deck block out. How to remove it.

5. A reinforcing member for reinforcing the periphery of the anti-slip bar according to claim 1, a body block including at least one recess for enclosing a shear stop bar, an injection hole for injecting mortar into the at least one recess, and at least one removal screw hole horizontally spaced from the injection hole; and at least one back block facing the at least one recess of the main block to form a space surrounding the anti-slip bar, A thin reinforcing member for a deck removal method, characterized in that the maximum height of the reinforcing member, which is the combination of the main block and the back block, is below the specific height range for removing concrete.

Images