Floor slab removing method of composite girder

Abstract

To provide a method for removing a floor slab of a composite girder capable of reducing concrete remaining on the girder.SOLUTION: Since a cutting-in 5 extending in the bridge-axis direction is formed from the upper surface side of a floor slab at each arrangement location of a slippage preventing member 4 of a floor slab 3, and the floor slab 3 on which the cutting-in 5 is formed is pulled upward from main girders 2 and removed, the resistance force between the slippage preventing member 4 and the concrete of the floor slab 3 against the tensile load can be reduced by the cutting-in 5, and the floor slab 3 can be easily separated from the main girders 2. Thus, since it is not necessary to cut the floor slab 3 in the bridge axial direction such that concrete remains on the main girder 2 as in the related art, the floor slab 3 on the main girder 2 can be lifted and removed at once without being divided in the direction perpendicular to the bridge axis. As a result, the efficiency of the removal work can be improved, and there is an advantage that a large-scale concrete crushing work is not required.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a composite girder deck removal method for removing an existing deck from a bridge made of composite girders and replacing it with a new deck. [Background technology]

[0002] Conventionally, bridges for public roads, expressways, and the like have been known to use composite girders in which a deck slab is installed by pouring concrete on steel girders, or by pouring concrete into a portion of a factory-fabricated deck. Composite girders have multiple shear stop members attached to the top surface of the steel girders, and the concrete for the deck is poured with the shear stop members embedded, or by pouring concrete into a portion of a factory-fabricated deck, thereby connecting the girder and the deck with the shear stop members. Furthermore, when the deck slab deteriorates, deck replacement work is carried out, in which the existing deck slab is removed and a new deck slab is reconstructed (see, for example, Figures 11 to 14 of Patent Document 1).

[0003] In conventional deck removal methods, the deck to be removed is first cut perpendicular to the bridge axis and divided along the bridge axis. However, because the shear stop members of the main girders are firmly bonded to the concrete of the deck, the deck cannot be lifted in this state. Therefore, the deck is cut along the bridge axis on both sides of the upper flange of the main girder, and the remaining portion of the main girder is lifted and removed using a crane or other device, leaving the concrete on the upper flange. After this, the remaining concrete on the main girder is crushed with a crusher, such as a large breaker or a hand-held breaker, and the concrete debris generated during the crushing process is removed and collected. The shear stop members are then cut and removed, the remaining concrete debris is removed, and the main girder is surface-finished. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2-292404 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional deck removal methods, the deck is cut in multiple locations along the bridge axis so that the concrete remains on the main girders, and then divided into multiple pieces perpendicular to the bridge axis. This requires the removal of each divided concrete block, which increases the labor required to remove the concrete blocks. Furthermore, because the concrete from the deck cut along the bridge axis remains on the main girders, the work of crushing the remaining concrete generates a large amount of concrete debris, which requires a great deal of effort to collect. In addition, the noise, vibration, and dust generated by the large-scale concrete crushing work continue for a long period of time, making this method unsuitable for work in urban areas.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a method for removing the deck slab of a composite girder that can improve the efficiency of the deck removal work and reduce the amount of concrete remaining on the girder. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the present invention provides a deck removal method for removing a deck from a composite girder in which a concrete deck is installed on a steel girder and the steel girder and deck are connected by a shear stopper member provided on the upper surface of the steel girder, in which at least one notch extending in at least one direction between the bridge axis direction and a direction forming a predetermined angle with the bridge axis direction is formed on the upper surface of the deck at each location of the shear stopper member on the deck, and the deck with the notch formed is removed upward from the steel girder.

[0008] As a result, the resistance force between the shear stop member and the concrete of the deck against tensile loads is reduced by the cuts, making it possible to easily separate the deck from the steel girder. [Effects of the Invention]

[0009] According to the present invention, the deck can be easily separated from the steel girder, eliminating the need to cut the deck in the bridge axis direction so that concrete remains on the girder, as in the conventional method. The deck on the girder can be lifted and removed in one go without dividing it in the direction perpendicular to the bridge axis. This improves the efficiency of the removal work. Furthermore, the amount of concrete remaining on the girder can be significantly reduced, which has the advantage of eliminating the need for large-scale concrete crushing work. This eliminates the need for a long time to remove and collect large amounts of concrete debris, and significantly reduces the noise, vibration, and dust generated by concrete crushing work, thereby minimizing the negative impact on neighboring areas, even when work is carried out in urban areas. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a composite girder showing a first embodiment of the present invention; [Figure 2] A perspective view of a stopper member [Figure 3] Front cross section of composite girder [Figure 4] A partial cross-sectional side view of a composite girder showing the deck removal process [Figure 5] A partial cross-sectional front view of a composite girder showing the deck removal process [Figure 6] A partial cross-sectional front view of a composite girder showing the deck removal process [Figure 7] A partial cross-sectional front view of a composite girder showing the deck removal process [Figure 8] A partial cross-sectional side view of a composite girder showing the deck removal process [Figure 9] Partial plan view of the deck showing the cuts [Figure 10] Partial side cross section of deck showing cuts [Figure 11] Partial front cross-section of the deck showing the cut [Figure 12] FIG. 10 is a partial plan view of a deck showing a cut according to a second embodiment of the present invention. [Figure 13] Partial front cross-section of the deck showing the cut [Figure 14]FIG. 10 is a partial plan view of a deck showing a cut according to a third embodiment of the present invention. [Figure 15] Partial front cross-section of the deck showing the cut [Figure 16] FIG. 10 is a partial plan view of a deck showing a cut according to a fourth embodiment of the present invention. [Figure 17] Partial side cross section of deck showing cuts [Figure 18] Partial front cross-section of the deck showing the cut DETAILED DESCRIPTION OF THE INVENTION

[0011] 1 to 11 show a first embodiment of the present invention, which illustrates a composite girder deck slab removal method for removing deteriorated deck slabs from an existing bridge made of composite girders.

[0012] The composite girder 1 shown in the figure is composed of a plurality of main girders 2 arranged parallel to one another and a concrete deck 3 installed on each main girder 2.

[0013] Each main girder 2 is made of a steel girder with an upper flange 2b and a lower flange 2c at the upper and lower ends of the web 2a, and is arranged in multiple rows (for example, three rows) at intervals in the direction perpendicular to the bridge axis. In addition, multiple shear stop members 4 are provided on the upper surface of the upper flange 2b to connect the main girder 2 to the deck slab 3.

[0014] The deck slab 3 is formed from concrete poured using formwork (not shown) onto the upper flanges 2b of each main girder 2, with wall parapets 3a integrally formed on both sides of the width direction. The deck slab 3 is joined to the main girders 2 by each of the shear stoppers 4, which are embedded in the concrete poured into the deck slab 3. In addition, asphalt pavement 3b is provided on the top surface of the deck slab 3.

[0015] The shear stopper 4 is a so-called block dowel (horseshoe-shaped dowel) consisting of a main body 4a made of steel plate bent into a U-shape and an annular reinforcing bar 4b bent into a U-shape. The annular reinforcing bar 4b extends diagonally upward from the main body 4a, with both ends joined to both widthwise sides of the main body 4a. The shear stopper 4 is arranged at intervals in the bridge axis direction on the upper flange 2b of the main girder 2 from one end to the other in the longitudinal direction, and the lower end of each main body 4a is welded to the upper flange 2b with the width direction of the main body 4a oriented perpendicular to the bridge axis.

[0016] Next, a method for removing the existing deck slab 3 in the composite girder 1 when replacing the deck slab will be described.

[0017] First, as shown in Figure 4, a diamond cutter D is moved in the bridge axis direction at each placement location of each shear stopper member 4 on the deck slab 3, thereby forming a vertical incision 5 extending in the bridge axis direction from the top surface of the deck slab 3. In this process, the incision 5 is formed in the widthwise center of the shear stopper member 4, leaving a predetermined height H from the top surface of the upper flange 2b of the main girder 2, and the incision 5 cuts the orbicular reinforcement 4b, which is part of the shear stopper member 4 inside the deck slab 3. In other words, the incision 5 is formed so that the height H from the bottom end of the incision 5 to the top surface of the upper flange 2b is higher than the main body 4a of the shear stopper member 4 but lower than the orbicular reinforcement 4b.

[0018] Next, after forming the notches 5 at the locations where each anti-slip member 4 will be located in the removal section of the deck slab 3, the deck slab 3 is cut perpendicular to the bridge axis at a predetermined position C1 in the bridge axis direction as shown in Figure 4, and the deck slab 3 is cut in the bridge axis direction at the widthwise outer end positions C2 of the main girders 2 on both sides in the width direction as shown in Figure 5, and the end side of the deck slab 3 including the wall parapet 3a is removed by a crane not shown as shown in Figure 6.

[0019] Next, as shown in Figures 7 and 8, the remaining portion of the deck slab 3 is lifted upward by a crane (not shown) and removed from above the main girder 2. At this time, the orbicular reinforcement 4b of the shear stopper 4 has been severed by the notch 5 formed in the deck slab 3, and because the notch 5 reaches below the upper end of the orbicular reinforcement 4b, the strength against so-called cone fracture that occurs around the orbicular reinforcement 4b due to an upward tensile load is reduced. As a result, the concrete around the shear stopper 4 fractures with a lower resistance than if the notch 5 were not present, and the deck slab 3 separates from the main girder 2, leaving the shear stopper 4 on the upper flange 2b.

[0020] After removing the existing deck slab 3 in the removal section as described above, the removal of the existing deck slab 3 is completed by removing the anti-slip members 4 remaining on each main girder 2.

[0021] Thus, according to this embodiment, at each location where the anti-slip member 4 is placed on the deck slab 3, a notch 5 extending in the bridge axis direction is formed on the top surface of the deck slab, and the deck slab 3 with the notch 5 formed thereon is pulled upward and removed from the main girder 2.Therefore, the resistance force between the anti-slip member 4 and the concrete of the deck slab 3 against tensile loads can be reduced by the notch 5, and the deck slab 3 can be easily separated from the main girder 2.

[0022] This eliminates the need to cut the deck slab 3 in the bridge axis direction so that concrete remains on the main girders 2, as was done in the past, and allows the deck slab 3 on the main girders 2 to be lifted and removed in one go without being divided in the direction perpendicular to the bridge axis, improving the efficiency of the removal work. In addition, the amount of concrete remaining on the main girders 2 can be significantly reduced, which has the advantage of eliminating the need for concrete crushing work. This means that it does not take a long time to remove and collect large amounts of concrete debris, and the noise, vibration, and dust caused by concrete crushing work are not generated, so the negative impact on neighboring areas can be reduced even when work is carried out in urban areas.

[0023] In addition, since the notch 5 is designed to cut a portion of the shear stopper member 4 inside the deck slab 3, the adhesion force and bearing pressure of the shear stopper member 4 to the concrete can be reduced, and the resistance force between the shear stopper member 4 and the concrete of the deck slab 3 can be further reduced.

[0024] Furthermore, the notch 5 is formed so as to leave a predetermined height H from the top surface of the main girder 2, so that the diamond cutter D does not come into contact with the upper flange 2b of the main girder 2 when forming the notch 5, and damage to the upper flange 2b can be reliably prevented.

[0025] Furthermore, in the first embodiment, only one notch 5 extending in the bridge axis direction is formed at the location of one shear stop member 4. However, as in the second embodiment shown in Figures 12 and 13 and the third embodiment shown in Figures 14 and 15, multiple notches 5 extending in the bridge axis direction may be formed at the location of one shear stop member 4. In this case, in the second embodiment, two notches 5 that cut the orbicular muscles 4b of the shear stop member 4 are formed spaced apart in the direction perpendicular to the bridge axis. Furthermore, in the third embodiment, in addition to the two notches 5 that cut the orbicular muscles 4b of the shear stop member 4, two other notches 5 located to the sides of the orbicular muscles 4b are formed spaced apart in the direction perpendicular to the bridge axis without cutting the orbicular muscles 4b.

[0026] In other words, by reducing the number of cuts 5, the amount of cutting labor required using the diamond cutter D can be reduced, and by increasing the number of cuts 5, the resistance force between the anti-slip member 4 and the concrete of the deck slab 3 can be further reduced.

[0027] Furthermore, while the first to third embodiments described above have shown the formation of a notch 5 extending in the bridge axis direction, two notches 5 extending perpendicular to the bridge axis (a direction forming a 90° angle with the bridge axis direction) may be formed, as in the fourth embodiment shown in Figures 16 to 18. In this fourth embodiment, one notch 5 is formed by cutting the orbicular reinforcement 4b of the shear stopper member 4 and positioned on one side of the front-to-rear direction (bridge axis direction) of the main body 4a, and the other notch 5 is formed by not cutting the orbicular reinforcement 4b and positioned on the other side of the front-to-rear direction of the main body 4a. In this case, as shown in Figure 17, the height H from the bottom end of the notch 5 to the top surface of the upper flange 2b can be reduced, allowing the depth of the notch 5 to be increased and reducing resistance to peeling off the deck slab 3. From the bottom of notch 5 Furthermore, the number and direction of the notches in the present invention are not limited to the above-mentioned embodiments, and notches may be formed that extend in both the bridge axis direction and in a direction perpendicular to the bridge axis, or notches may be formed that extend diagonally horizontally relative to the bridge axis direction.

[0028] Furthermore, in each of the above embodiments, a block dowel is shown as the anti-slip member 4, but the anti-slip member is not limited to a block dowel, and may be an anti-slip member having another shape, such as a stud dowel.

[0029] Furthermore, in the above embodiment, the main girder 2 is shown as a steel girder having an upper flange 2b and a lower flange 2c at the upper and lower ends of the web 2a, respectively, but it may also be a steel girder of other shapes, such as a box girder. [Explanation of symbols]

[0030] 1...composite girder, 2...main girder, 3...deck slab, 4...slip prevention member, 5...notch.

Claims

1. A method for removing a deck slab from a composite girder in which a concrete deck slab is installed on a steel girder and the steel girder and the deck slab are connected by a shear stopper member provided on the top surface of the steel girder, At least one notch extending in at least one direction between the bridge axis direction and a direction forming a predetermined angle with the bridge axis direction is formed from the upper surface side of the deck for each placement location of the shear stopper member of the deck, Remove the deck slab with the notch upward from the steel girder. A composite girder deck removal method characterized by the above.

2. The cut is used to cut a portion of the shear stopper member in the deck.

2. The composite girder deck slab removal method according to claim 1.

3. The cut is formed leaving a predetermined height from the top surface of the steel girder.

3. The composite girder deck slab removal method according to claim 1 or 2.

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