Removal method of displacement prevention member and removal method of floor slab

Abstract

To provide a method for efficiently removing a displacement prevention member without leaving the displacement prevention member on a steel main girder in a method for removing the displacement prevention member and a method for removing a floor slab.SOLUTION: A displacement prevention member 4 is fixed to a steel main girder 3 by a welding part 17. First, a worker puts a cut 18 in a part of the welding part 17. Next, the worker strikes the displacement prevention member 4 from the side of the part of the displacement prevention member 4 in which the cut 18 is placed. This strike breaks the welding part 17, and the displacement prevention member 4 is separated from the steel main girder 3.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method for removing a shear stopper member fixed to a steel main girder by welding, and a method for removing a deck slab of a composite girder that includes such a shear stopper member. [Background technology]

[0002] A composite girder is an integrated structure of a steel girder and a reinforced concrete deck by embedding a shear stopper installed on the top surface of the steel girder into the deck. Patent Document 1 describes a method in which the concrete part of the deck of a composite girder and the shear stopper are cut horizontally together using a wire saw, and then separated and removed from the steel girder.

[0003] Patent Document 2 describes an apparatus equipped with a first cutting means for horizontally cutting the concrete portion and the shear stopper member, and a second cutting means for cutting both the left and right sides of the concrete portion. The first and second cutting means are wire saws or the like. By cutting into both the left and right sides of the steel main girder of the deck with the second cutting means, and simultaneously cutting into the deck directly above the upper flange of the steel main girder, the concrete portion of the deck and the shear stopper member are cut horizontally together, and the deck is separated and removed from the steel main girder.

[0004] Patent Document 3 describes a method for demolishing a concrete deck using a water jet method. When demolishing a deck using a water jet method, after the concrete portion is removed, the shear stopper member remains on the steel main girder. Patent Document 3 does not describe the remaining shear stopper member, but it is known that the base of the remaining shear stopper member is cut by a metal slicer or gas cutting, and the shear stopper member is removed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-145668 A [Patent Document 2] JP 2019-31868 A [Patent Document 3] Japanese Patent Application Publication No. 64-48972 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above method, the base of the shear stopper remains on the steel girder. In deck replacement work, a new deck may be constructed using precast concrete members on the existing steel girder. In such cases, it is desirable to remove the base of the shear stopper remaining on the steel girder.

[0007] In addition, when cutting the shear stopper using a metal slicer, the weight of the cut material acts on the blade of the metal slicer, reducing the cutting efficiency and causing the blade to wear out quickly. For example, when a horseshoe dowel (block dowel) is used as the shear stopper, cutting the base of the horseshoe dowel horizontally using a metal slicer takes about 30 minutes per section for a team of two people, one to operate the machine and one to collect the dust. In addition, when gas cutting the shear stopper, the heat generated during cutting is transferred to the steel main girders, raising concerns that this could cause deformation in the upper flange of the steel main girders.

[0008] In view of the above background, the present invention has an objective of providing a method for removing a shear stopper member and a method for removing a deck slab, which does not leave the shear stopper member on the steel main girder and can efficiently remove the shear stopper member. [Means for solving the problem]

[0009] In one aspect of the present invention, which aims to solve the above-mentioned problems, a method for removing a shear stopper member (4) fixed to a steel main girder (3) by a welded portion (17) includes the steps of making a notch (18) in a part of the welded portion, and separating the shear stopper member from the steel main girder by applying a strike to the shear stopper member from the side of the part where the notch has been made. Also, in one aspect of the present invention, which aims to solve the above-mentioned problems, a method for removing a deck slab (2) including a shear stopper member (4) fixed to a steel main girder (3) by a welded portion (17) and a concrete portion (5) in which the shear stopper member is embedded includes the steps of removing the concrete portion to expose the welded portion, making a notch (18) in a part of the welded portion, and separating the shear stopper member from the steel main girder by applying a strike to the shear stopper member from the side of the part where the notch has been made.

[0010] According to this embodiment, after a cut is made in part of the weld, the remainder of the weld is broken by striking, and the shear stopper is separated from the steel main girder, so that the entire shear stopper can be removed from the steel main girder. Also, the shear stopper can be removed by a single worker, and the work time is shorter than when the shear stopper itself is cut horizontally.

[0011] In the above aspect, the anti-slip member (4) includes a horseshoe-shaped dowel including a base (9) fixed to the steel main girder (3) by the weld (17) and a ring reinforcing bar (10) extending from the base, the base has a rectangular shape including a pair of long sides (9a) and a pair of short sides (9b) in a plan view, the weld extends along the pair of long sides and the pair of short sides, the step of making the notch (18) includes making the notch in a portion of the weld extending along one of the pair of long sides and both of the pair of short sides, and the step of separating includes applying a strike to a side of the base from the side of the one of the pair of long sides.

[0012] According to this embodiment, incisions are made along one of a pair of long sides and along both of a pair of short sides of the weld, and an impact is applied to the base from the side of the long side where the incisions are made, so that the unnotched parts of the weld can be crushed relatively easily.

[0013] In the above aspect, it is preferable that the portion of the welded portion (17) along the other of the pair of long sides (9a) is not cut in the cutting step, but is broken by the impact in the separating step.

[0014] According to this embodiment, since the portion along the other of the pair of long sides is broken by impact without making an incision therein, the amount of work required for making the incisions can be reduced.

[0015] In the above aspect, it is preferable to further include a step of cutting and removing the ring reinforcing bar (10) at portions (10a) near both ends thereof, which is performed before the step of making the incisions (18).

[0016] According to this aspect, it is possible to prevent a worker from tripping over the ring reinforcing bar and falling when removing the ring reinforcing bar.

[0017] In the above aspect, the step of making the incisions (18) may be performed using a hand-held rotary tool (19) having a cutter disc (19a) attached to a rotating portion.

[0018] In the case of gas cutting, there is a concern that the steel main girder may be deformed due to heat, but in this embodiment, since a rotating tool is used, there is no risk of deformation due to heat. In addition, since it is a handheld tool, the effort of setting up the tool is eliminated, and the work time can be shortened.

[0019] In the above aspect, it is preferable to further include a step of removing the welded portion (17) remaining on the surface of the steel main girder (3) after the separating step.

[0020] According to this embodiment, since the anti-slip member does not remain on the steel main girder, it is relatively easy to remove the remaining portion of the welded portion.

[0021] In the above aspect, the exposing step may include crushing the concrete portion (5) using an impact generating agent.

[0022] According to this aspect, it is possible to efficiently remove the concrete portion to expose the shear stopper member. Effect of the Invention

[0023] According to the above aspects, it is possible to provide a method for removing a shear stopper member and a method for removing a deck slab, in which the shear stopper member does not remain on the steel main girder and can be efficiently removed. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view showing an upper portion of a bridge including a deck to which a method according to an embodiment is applied; [Diagram 2] A plan view of a deck in the middle of applying the method according to the embodiment [Diagram 3] A partial cross-sectional front view of a deck slab in the middle of being applied with the method according to the embodiment (viewed from the bridge width direction) [Figure 4] A: Cross-sectional view taken along line AA in FIG. 2; B: Cross-sectional view taken along line BB in FIG. 2 [Diagram 5] FIG. 1 is an explanatory diagram (partially sectional front view) of a deck to which a method according to an embodiment is applied; [Figure 6] FIG. 1 is a plan view illustrating a method according to an embodiment (after removal of concrete); [Figure 7] A cross-sectional view taken along line AA in FIG. 6 (step of making a cut) [Figure 8] A cross-sectional view taken along line AA in FIG. 6 (hitting step) [Figure 9] Cross-sectional view along line AA in Figure 6 (after impact) [Figure 10] Cross-sectional view along line AA in Figure 6 (after scraping) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0026] 1 is a perspective view of the upper part of a bridge 1 to which a method according to an embodiment is applied, showing a state in which a deck 2 has been partially removed. The bridge 1 includes a substructure (not shown), a steel girder 3 including an H-shaped steel supported by the substructure and extending in the bridge axis direction, and a deck slab 2 made of reinforced concrete supported by the steel girder 3.

[0027] As shown in Figures 2 and 3, a horseshoe-shaped dowel 4 is fixed by welding or the like to the upper surface of the upper flange 3a of the steel main girder 3 as a slip prevention member. The horseshoe-shaped dowel 4 is embedded in the concrete part 5 of the deck slab 2, so that the deck slab 2 is integrated with the steel main girder 3 to form a composite girder. The deck slab 2 includes vertical bars 6 extending in the bridge axis direction, horizontal bars 7 extending in the bridge width direction, reinforcing bars 8 arranged in pairs surrounding one horseshoe-shaped dowel 4 in a plan view, and the concrete part 5 in which the horseshoe-shaped dowel 4, vertical bars 6, horizontal bars 7, and reinforcing bars 8 are embedded.

[0028] The horseshoe dowel 4 includes a steel base 9 fixed to the upper surface of the upper flange 3a of the steel main girder 3 by welding or the like, and a U-shaped steel ring reinforcing bar 10 with both ends fixed to the base 9 by welding or the like. The base 9 extends in the bridge width direction and has a block or plate shape. Both ends of the base 9 may be curved so as to face the bridge axis direction. The ring reinforcing bar 10 includes a U-shaped steel rod with both ends spaced apart from each other in the bridge width direction, inclined with respect to the up-down direction as viewed from the bridge width direction, and combined with the base 9 to form a ring shape in plan view. A plurality of horseshoe dowels 4 are arranged on each steel main girder 3 so as to be lined up in a row along the bridge axis direction.

[0029] When dismantling the deck 2, first, as shown in Fig. 1, the non-girder portions 12 are removed so that girder portions 11 having a width slightly wider than both ends of the steel main girders 3 in the width direction remain on the steel main girders 3. The non-girder portions 12 include a portion between two adjacent girder portions 11 and a portion on the outer side in the bridge width direction of the girder portions 11 on the steel main girders 3 arranged at the ends in the bridge width direction.

[0030] In order to remove the non-girder portion 12 from the deck 2, while the non-girder portion 12 is supported by temporary members (not shown), a worker cuts the boundary between the non-girder portion 12 and the girder portion 11 vertically along the bridge axis direction using a cutting device (not shown) such as a concrete cutter. In addition, if necessary, the worker cuts the deck slab 2 vertically along the bridge width direction using the cutting device to divide the deck slab 2 into pieces of a weight that can be lifted by a crane (not shown) and a weight and size that can be transported by a transport machine (not shown) such as a truck. The worker lifts the divided non-girder portion 12 with a crane and loads it onto the transport machine for transport.

[0031] Next, as shown in Figures 2 to 4, the worker drills the first charge hole 13 and the second charge hole 14 based on the positions of the horseshoe dowel 4, the vertical reinforcement 6, the horizontal reinforcement 7, and the reinforcing bar 8 that have been previously investigated. After that, the worker charges the first charge hole 13 with the first impact generating agent 15, and charges the second charge hole 14 with the second impact generating agent 16.

[0032] The positions of the horseshoe dowels 4, the vertical bars 6, the horizontal bars 7, and the reinforcing bars 8 can be determined based on the reinforcement diagram of the deck slab 2. If necessary, workers can determine these positions using a rebar detector or the like.

[0033] The first charge hole 13 and the second charge hole 14 are drilled downward from the upper surface of the deck 2. One first charge hole 13 and one second charge hole 14 are drilled for one horseshoe-shaped dowel 4. In a plan view, the first charge hole 13 is provided inside the ring shape formed by the base 9 and the ring reinforcing bar 10, and the second charge hole 14 is provided on the opposite side of the bridge axis direction from the first charge hole 13 with respect to the base 9. Note that, if the arrangement of the first impact generating agent 15 and the second impact generating agent 16 satisfies a predetermined condition, the first charge hole 13 and the second charge hole 14 may be inclined with respect to the vertical direction, and may be drilled from the side of the girder part 11. Also, the drilling of the first charge hole 13 and the second charge hole 14 and the charging of the first impact generating agent 15 and the second impact generating agent 16 may be performed before removing the non-girder part 12 (see FIG. 1). If vertical reinforcement bars 6, horizontal reinforcement bars 7 or reinforcing bars 8 are present in a suitable position for the first and second charging holes 13 and 14, workers may cut these reinforcing bars to provide the first and second charging holes 13 and 14, or may provide the first and second charging holes 13 and 14 by shifting them from these reinforcing bars if the positions of the first and second impact generating agents 15 and 16 satisfy the specified conditions described below.

[0034] The first impact generating agent 15 and the second impact generating agent 16 are charged at the bottom of the first charging hole 13 and the second charging hole 14. The first impact generating agent 15 is arranged inside the ring shape formed by the base 9 and the ring reinforcing bar 10 in a plan view, and is arranged below the ring reinforcing bar 10 when viewed from the bridge width direction.

[0035] In plan view, the distance from the center of the second impact generator 16 to the base 9 is 60 mm or less, and the second impact generator 16 is preferably arranged as close to the base 9 as possible. Therefore, the distance from the second impact generator 16 to the base 9 is shorter than the distance from the first impact generator 15 to the base 9. The value of 60 mm or less was identified based on experimental results. The distance from the lower end of the second impact generator 16 to the upper surface of the upper flange 3a of the steel main girder 3 is 60 mm or less. In the illustrated embodiment, the distance from the lower end of the first impact generator 15 to the upper surface of the upper flange 3a of the steel main girder 3 and the distance from the lower end of the second impact generator 16 to the upper surface of the upper flange 3a of the steel main girder 3 are equal to each other. Therefore, the depths of the first charge hole 13 and the second charge hole 14 can be made common to each other, and construction errors such as the drilling depths of the first charge hole 13 and the second charge hole 14 being reversed can be prevented.

[0036] In order to separate the deck 2 from the steel girder 3, it is important to crush the restraint area A (see FIG. 5) of the concrete part 5, which is sandwiched between the upper flange 3a of the steel girder 3 and the ring reinforcing bar 10. When placing importance on crushing the restraint area A, it is desirable to place the first impact generator 15 approximately in the center of the ring shape formed by the base 9 and the ring reinforcing bar 10 in a plan view. Here, "approximately in the center" means that it also includes the case where it is shifted from the center by an amount necessary to drill the first charge hole 13 while avoiding the vertical reinforcement 6, the horizontal reinforcement 7, or the reinforcing bar 8.

[0037] In addition, when the crushing of the portion between the horseshoe-shaped dowels 4 adjacent to each other in the concrete portion 5 is important, the first impact generating agent 15 and the second impact generating agent 16 are arranged so that the intervals between them are as even as possible. That is, each first impact generating agent 15 is arranged so that the distance L1 between the first impact generating agent 15 and the adjacent second impact generating agent 16 across the base 9 and the distance L2 between the first impact generating agent 15 and the adjacent second impact generating agent 16 without the base 9 are shifted in a direction closer to each other than the center in the bridge axis direction of the ring shape formed by the base 9 and the ring reinforcing bar 10 in a plan view. In the illustrated example, the first impact generating agent 15 is arranged at a position farther from the base 9 than the center in the bridge axis direction of the ring shape formed by the base 9 and the ring reinforcing bar 10 in a plan view, so that the intervals between the first impact generating agent 15 and the second impact generating agent 16 are made to be even. In a plan view, the distance between the bases 9 of two adjacent horseshoe-shaped dowels 4 is L, the distance between the first impact generating agent 15 and the second impact generating agent 16 adjacent to each other with the base 9 in between is L1, and the distance between the first impact generating agent 15 and the second impact generating agent 16 adjacent to each other without the base 9 in between is L2. It is preferable that 0.4L≦L1≦0.6L and 0.4L≦L2≦0.6L, and it is even more preferable that L1 ≒ L2.

[0038] When a horseshoe-shaped dowel 4 of standard dimensions (width: 180 mm to 250 mm, height: 180 mm to 220 mm) is used, the first impact generating agent 15 and the second impact generating agent 16 preferably apply an impact to an area within 60 mm from the upper surface of the upper flange 3a of the steel main girder 3 with a maximum pressure of 1.8 GPa to 2.4 GPa and a maximum pressure arrival time of 25 microseconds to 35 microseconds. Examples of the first impact generating agent 15 and the second impact generating agent 16 that satisfy such conditions include nitromethane-based impact generating agents and impact generating agents containing a mixture of aluminum powder and metal oxide powder. It is preferable that the types of agents used for the first impact generating agent 15 and the second impact generating agent 16 are the same as each other.

[0039] Next, the worker simultaneously detonates the first impact generating agents 15 and the second impact generating agents 16 arranged so as to be substantially aligned in the bridge axis direction. This causes the concrete portion 5 of the deck 2, particularly the restraint area A (see FIG. 5), to be crushed. The worker removes the crushed concrete portion 5, the vertical bars 6, the horizontal bars 7, and the reinforcing bars 8.

[0040] By removing the concrete portion 5 and the like as described above, the upper surface of the upper flange 3a of the steel main girder 3 and the horseshoe dowel 4 are exposed. The removal work of the horseshoe dowel 4 is performed as follows.

[0041] As shown in Fig. 6, the base 9 of the horseshoe dowel 4 has a rectangular parallelepiped shape and has a pair of long sides 9a and a pair of short sides 9b in a plan view. The base 9 is placed on the upper surface of the upper flange 3a of the steel main girder 3 and is fixed to the upper surface of the upper flange 3a via a weld 17 formed on its lower side surface by fillet welding. The weld 17 is provided over the entire pair of long sides 9a and the pair of short sides 9b on the lower side surface of the base 9. The weld 17 is exposed by removing the concrete portion 5 described above.

[0042] First, the worker cuts off the vicinity 10a of both ends of the ring reinforcing bars 10 for all exposed horseshoe dowels 4, and separates and removes most of the ring reinforcing bars 10 from the base 9. The ring reinforcing bars 10 are cut, for example, by gas cutting or by a tool that makes an incision 18 in the welded portion 17 described later. This work is not essential for the removal of the horseshoe dowels 4 itself, but is preferably performed to prevent the worker from tripping over the ring reinforcing bars 10 and falling. Note that if other safety measures are taken, for example, if a protective gear such as a triangular cone is placed over the exposed horseshoe dowels 4 until the work described below is started to prevent the worker from tripping over the ring reinforcing bars 10, the cutting work of the ring reinforcing bars 10 may be omitted.

[0043] Next, as shown in FIG. 7, the worker makes a cut 18 in the welded portion 17 in a portion extending along one of the pair of long sides 9a and both of the pair of short sides 9b (see FIG. 6). The cut 18 is preferably made over the entire length of the portion extending along one of the pair of long sides 9a and both of the pair of short sides 9b (see FIG. 6). The other of the pair of long sides 9a does not need the cut 18, but the cut 18 may be made partially or shallowly. The cut 18 is preferably made toward the intersection line between the side surface of the base 9 and the upper surface of the upper flange 3a, and reaches the intersection line. In order to prevent the cut 18 from being made in the upper flange 3a of the steel main girder 3, a small amount of the welded portion 17 may remain between the tip of the cut 18 and the upper surface of the upper flange 3a, and the cut 18 may be made slightly above the intersection line. The work of forming the notches 18 may be performed, for example, by a rotary tool 19 having a cutter disk 19a attached to a rotating portion. The rotary tool 19 is preferably a hand-held tool, such as a sander or grinder.

[0044] Next, as shown in Fig. 8, the worker applies a strike with a hammer 20 to the side of the base 9 including the long side 9a on the side where the notch 18 has been made in the welded portion 17. The strike with the hammer 20 is preferably applied in a direction perpendicular to the side where the strike is applied, that is, from the side including the long side 9a on the side where the notch 18 has been made in the welded portion 17 toward the side including the long side 9a on the side where the notch 18 has not been made. This strike breaks the portion of the welded portion 17 from the tip of the notch 18 to the upper surface of the upper flange 3a or the side of the base 9, and the welded portion 17 on the side of the long side 9a where the notch 18 has not been made, and the horseshoe dowel 4 separates from the upper flange 3a.

[0045] Next, as shown in Figures 8 and 9, the worker performs scraping work. That is, the worker removes the remainder of the welded portion 17 remaining on the upper surface of the upper flange 3a using a sander or the like.

[0046] After removing the horseshoe dowels 4 (see FIG. 6) as described above, workers construct a new deck slab (not shown) on the steel main girder 3.

[0047] The effects of this embodiment will be described with reference to FIGS.

[0048] After a worker makes a notch 18 in part of the welded portion 17, the remaining part of the welded portion 17 is broken by striking it, so the entire base 9 can be removed from the steel main girder 3, reducing the amount of scraping work. Also, the horseshoe dowel 4 can be removed by a single worker, so the work time is shorter than when the base 9 is cut horizontally.

[0049] Since the rotary tool 19 is handheld, the labor required for setting up the tool is eliminated, and the work time can be shortened. In addition, since the cuts 18 are made by the rotary tool 19 with the cutter disk 19a attached to the rotating part, there is no deformation due to heat of the upper flange 3a of the steel main girder 3, which is a concern when gas cutting is used. In addition, since the cuts 18 are not substantially made in the base 9 itself, the decrease in work efficiency due to friction with the material to be cut and the wear of the blade due to abrasion are suppressed.

[0050] Since notches 18 are made in the portions along one of the pair of long sides 9a and both of the pair of short sides 9b at the welded portion 17, by striking the base 9 from the side of the long side 9a where notches 18 are made, the portion of the welded portion 17 along the other of the pair of long sides 9a where notches 18 are made can be relatively easily crushed.

[0051] Since the ring reinforcing bars 10 are cut before the removal work of the base 9, the worker is prevented from tripping over the ring reinforcing bars 10 and falling, thereby improving the safety of the worker.

[0052] As shown in FIG. 3, the concrete part 5 is broken using the first and second impact generators 15, 16. The compressive stress wave generated by the detonation of the first and second impact generators 15, 16 is reflected by the upper surface of the upper flange 3a of the steel main girder 3 and converted into a tensile stress wave. The tensile stress wave propagates inside the concrete 5 and inside the horseshoe-shaped dowel 4. The tensile stress wave propagating inside the horseshoe-shaped dowel 4 propagates faster than the tensile stress wave propagating inside the concrete part 5 with almost no attenuation, and the propagation point becomes a new wave source and propagates inside the concrete part 5. The tensile stress waves propagated by different paths collide with each other in the concrete part 5, overlap, and interfere with each other, forming a complex propagation path of the tensile stress wave, and the concrete part 5 is broken into small pieces. This method of breaking the concrete part 5 can break the concrete part 5 in a short time compared to the water jet method. EXAMPLES

[0053] Based on the above embodiment, a notch 18 was made in the welded portion 17 along one of the pair of long sides 9a and both of the pair of short sides 9b, and no notch 18 was made in the other of the pair of long sides 9a, and the side surface of the base 9 was struck with a hammer 20 from the side of the long side 9a where the notch 18 was made, thereby separating the base 9 from the upper flange 3a of the steel main girder 3. In addition, as a comparative example, a metal slicer was used to horizontally cut the root of the base 9, thereby separating most of the base 9 from the upper flange 3a of the steel main girder 3.

[0054] In the method based on the above embodiment, the removal work could be performed by one worker, and 20 horseshoe dowels 4 could be removed in one day's work time (8 hours including breaks). On the other hand, in the method of the comparative example, the work required a pair of two people, one to operate the machine and one to collect the dust, and it took about 30 minutes to remove one horseshoe dowel 4. The amount of work in the method of the comparative example converted into one man-hour (the amount of work completed by one worker in one day) is the removal of just under eight horseshoe dowels 4. Thus, compared to the comparative example, the method based on the above embodiment significantly improved the efficiency of the horseshoe dowel 4 removal work.

[0055] Although the description of the specific embodiment is finished above, the present invention is not limited to the above embodiment and modified examples, and can be widely modified. For example, the present invention may be applied to a horseshoe-shaped dowel 4 whose base 9 is not rectangular but U-shaped in plan view, and may be applied to a shear stopper member such as a perforated steel plate dowel or a stud dowel instead of the horseshoe-shaped dowel 4. The present invention may be applied when it becomes necessary to change the installation position of the shear stopper member after the shear stopper member is installed in the construction work of a newly constructed composite girder. The concrete portion 5 may be removed by a water jet method, or may be removed by cutting the concrete portion 5 together with the shear stopper member as in Patent Documents 1 and 2, and then chipping the concrete around the remaining part of the shear stopper member. [Explanation of symbols]

[0056] 1: Bridge 2: Floor slab 3: Steel girder 3a: Top flange 4: Horseshoe dowel (anti-slip member) 5: Concrete section 9: Base 9a: Long side 9b: Short side 10: Ring reinforcing bars 10a: Near the ends 17: Welded section 18: Cut 19: Rotary tools 19a: Cutter disc

Claims

1. A method for removing a shear stopper member fixed to a steel main girder by a weld, comprising the steps of: making a notch in a portion of the weld; A step of separating the anti-slip member from the steel main girder by striking the anti-slip member from the side of the part where the notch is made. A removal method comprising:

2. The anti-slip member includes a horseshoe dowel including a base portion fixed to the steel main girder by the welded portion and a ring reinforcing bar extending from the base portion, The base portion has a rectangular parallelepiped shape including a pair of long sides and a pair of short sides in a plan view, The welds extend along the pair of long sides and the pair of short sides, the step of making the incision includes making the incision in a portion of the weld extending along one of the pair of long sides and both of the pair of short sides; The removal method according to claim 1 , wherein the separating step includes striking a side surface of the base from the one of the pair of long sides.

3. The removal method according to claim 2 , wherein a portion of the welded portion along the other of the pair of long sides is not cut in the cutting step, and is broken by the impact in the separating step.

4. 3. The method of claim 2, further comprising the step of cutting and removing the ring reinforcing bar near both ends thereof, performed prior to the step of making the cuts.

5. The removal method according to claim 1 , wherein the step of making the cut is performed using a hand-held rotary tool having a cutter disk attached to a rotating part.

6. The removal method according to claim 1 , further comprising a step of removing the weld remaining on the surface of the steel main girder, performed after the separating step.

7. A method for removing a deck including a shear stopper member fixed to a steel girder by a welded portion and a concrete portion in which the shear stopper member is embedded, comprising: removing the concrete portion to expose the weld; making a notch in a portion of the weld; A step of separating the anti-slip member from the steel main girder by striking the anti-slip member from the side of the part where the notch is made. A removal method comprising:

8. The removal method according to claim 7 , wherein the exposing step includes fracturing the concrete section using an impact generating agent.

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